JP2020085492A - Mechanical stability evaluation method of resin emulsion - Google Patents

Abstract

To provide a new method capable of evaluating the mechanical stability of resin emulsion.SOLUTION: A mechanical stability evaluating method of resin emulsion is provided which includes: a first measurement process of measuring an average particle diameter Dby a laser diffraction/scattering method of the resin emulsion; a second measurement process of measuring an average particle diameter Dby a dynamic light scattering method of the resin emulsion; a calculation process of calculating, from the measured average particle diameter Dand the average particle diameter D, the D/Das the ratio of them; and an evaluation process of evaluating the quality of the mechanical stability of the resin emulsion on the basis of the value of the D/D.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resin emulsion mechanical stability evaluation method and a resin emulsion.

Resin emulsions in which resin particles are dispersed in an aqueous medium are widely used, for example, in the fields of adhesives, pressure-sensitive adhesives, paints, inks, paper processing, and fiber processing. In fields such as these, resin emulsions include, for example, compounding with other materials, mixing, stirring, liquid feeding by various pumps (eg gear pump and plunger pump), and various coating machines (eg roll coating). In each process such as coating with a machine or a spray coater, etc., it receives a mechanical action such as mechanical shearing force.

When kinetic energy is applied to the resin particles in the emulsion due to the mechanical action of the resin emulsion, the resin particles come into contact with each other and adhere to each other to easily form an aggregate. When such agglomerates are generated in the various steps as described above, the resin emulsion becomes difficult to exhibit its original function, which may be a factor that deteriorates the quality of the product manufactured using the resin emulsion. ..

Therefore, a resin emulsion having low dispersion stability (hereinafter, referred to as “mechanical stability”), which is so to speak a resistance to mechanical action, is likely to be restricted in various steps as described above, and therefore, is produced. Sex tends to be low. From such circumstances, mechanical stability is mentioned as one of the performances required for the resin emulsion.

Various techniques for improving the mechanical stability of resin emulsions have been proposed so far. For example, in Patent Document 1, a polymer emulsion obtained by polymerizing a monomer mixture such as (meth)acrylic acid ester dispersion-stabilized with a water-soluble polymer protective colloid in the presence of alcohol is mechanically stable. Suggestions have been made to improve the sex. In addition, for example, in Patent Document 2, in a water-based emulsion in which a predetermined vinyl alcohol-based polymer is used as a dispersant and a polymer composed of a (meth)acrylic acid ester-based monomer unit is used as a dispersoid, mechanical stability and the like are improved. Suggestions have been made to increase it. Further, for example, Patent Document 3 proposes an aqueous emulsion excellent in mechanical stability, which contains a vinyl alcohol-based polymer having a predetermined structure and a polymer mainly composed of an ethylenically unsaturated monomer unit. There is.

JP, 11-335490, A JP, 2005-133077, A JP2012-57073A

As described in Examples of Patent Documents 1 to 3 described above, a Marlon mechanical stability tester is used to evaluate the mechanical stability of the resin emulsion. By using this tester, the rotor is rotated under a constant load to apply shear stress to the resin emulsion to generate aggregates (coagulated components) of the resin emulsion. It can be evaluated that the stability is good.

The inventors of the present invention also used a Marlon type mechanical stability tester to evaluate and confirm the mechanical stability of the resin emulsion produced, while providing a configuration for improving the mechanical stability of the resin emulsion. I was studying hard. In the examination, the present inventors have found that, for the resin emulsion having good mechanical stability, there is a peculiar constitution regarding the average particle diameter, and the method for evaluating mechanical stability The present invention has been accomplished through the idea of using it for. In addition, in the above study, a structure was found in which the mechanical stability of the resin emulsion was better, leading to the present invention.

That is, the present invention aims to provide a novel method capable of evaluating the mechanical stability of a resin emulsion. In addition, the present invention is intended to provide a resin emulsion having better mechanical stability.

The present invention provides a first measurement step of measuring an average particle diameter D _A of a resin emulsion by a laser diffraction/scattering method, and a second measurement step of measuring an average particle diameter D _B of the resin emulsion by a dynamic light scattering method. Based on the step, a calculation step of calculating the ratio D _A /D _B from the measured average particle size D _A and the measured average particle size D _B , and the value of D _A /D _B , An evaluation step of evaluating the mechanical stability of the resin emulsion is provided, and a mechanical stability evaluation method of the resin emulsion is provided.

Further, the present invention provides a resin particle (I) comprising a particle in which a monomer component is polymerized and an adsorption protective layer in which a polycarboxylic acid type polymer compound is adsorbed on the surface of the particle, and (meth)acrylic acid. A resin particle corresponding to at least one of the resin particles (II) obtained by polymerizing the monomer component contained, and having an average particle diameter D _A by a laser diffraction/scattering method and an average particle diameter D _B by a dynamic light scattering method. Zeta potential measured under the same conditions for the same resin emulsion except that the ratio D _A /D _B is less than 1 and the zeta potential does not include the polycarboxylic acid type polymer compound and the (meth)acrylic acid. There is provided a resin emulsion having an absolute value of the difference of 10 mV or more.

According to the present invention, it is possible to provide a novel method capable of evaluating the mechanical stability of a resin emulsion. Further, according to the present invention, a resin emulsion having better mechanical stability can be provided.

It is a flowchart which shows an example of the mechanical stability evaluation method of the resin emulsion of one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

<Method for evaluating mechanical stability of resin emulsion>
The present inventors have conducted a study for obtaining a resin emulsion having good mechanical stability while evaluating and confirming the mechanical stability using a Marlon type mechanical stability tester. As a result, mechanical stability tends to be good in the case of a structure having an adsorption protective layer or a water-soluble protective colloid on the surface of particles in a resin emulsion or a structure having structural units derived from (meth)acrylic acid in the particles. We found that there is a tendency. As a result of further studies by the present inventors based on this finding, a group of resin emulsions having good mechanical stability, and a group of resin emulsions equivalent to those having no above-mentioned constitution, with respect to the average particle diameter. It turns out that there is a difference in composition. Specifically, a configuration relating to the average particle diameter, the D _{A /} D _B is the ratio of the average particle diameter D _B by the average particle of the resin emulsion by a laser diffraction scattering method diameter D _A and dynamic light scattering method It was found to correlate with the mechanical stability of the resin emulsion. From this, the present inventors consider that the mechanical stability of the resin emulsion can be evaluated by the value of D _A /D _B , and as a result of examination based on that idea, the present invention is completed. Came to.

That is, the method for evaluating the mechanical stability of a resin emulsion of one embodiment of the present invention (hereinafter, may be simply referred to as “the present evaluation method”) is the stability of a resin emulsion against mechanical action (machine Stability). Then, as shown in FIG. 1, the present evaluation method includes a step (first measurement step) S11 of measuring an average particle diameter D _A of a resin emulsion by a laser diffraction/scattering method, and a dynamic light scattering method of the resin emulsion. The step (second measurement step) S12 of measuring the average particle diameter D _{B according} to step S12 is included. Further, the present evaluation method includes a step (calculation step) S13 of calculating the ratio D _A /D _B from the measured average particle diameter D _A and the average particle diameter D _B (calculation step), and D _A /D _B. A step (evaluation step) S14 of evaluating the quality of mechanical stability of the resin emulsion based on the value is included.

According to this evaluation method, the quality of mechanical stability of the resin emulsion can be evaluated based on the value of D _A /D _B , which is the ratio of the average particle diameters of the two types of the resin emulsion. Therefore, according to the present evaluation method, it becomes possible to evaluate the mechanical stability of the resin emulsion without conducting the test using the Marlon type mechanical stability tester. Since the average particle size used in the present evaluation method is widely used as information indicating the general properties of resin emulsions, the present evaluation method can omit a test only for evaluating mechanical stability. It can be said that it is useful in industry because it is connected. Further, the combined use of the present evaluation method and the test using the above tester can provide more reliable information on the mechanical stability of the resin emulsion. Therefore, the present evaluation method can be more useful when the resin emulsion product is used, manufactured, and sold.

In the present specification and claims (hereinafter referred to as "the present specification"), the average particle diameter D _A of the resin emulsion (resin particles contained therein) by the laser diffraction/scattering method is the laser It means a particle size (D ₅₀ ) at which cumulative 50% in a volume-based particle size distribution is measured by a diffraction/scattering method. In the laser diffraction/scattering method, the particle diameter is measured by measuring the angle dependence of the intensity of light scattered when a laser beam passes through a particle sample dispersed in a liquid medium in a resin emulsion. In the case of a large particle, light is scattered at a small angle with respect to the laser beam, and in the case of a small particle, light is scattered up to a large angle with almost the same intensity. After that, the data for each angle is analyzed, and the particle diameter producing the diffraction/scattering pattern is calculated by using Franhofer diffraction theory, Mie scattering theory, or the like. As described above, in the laser diffraction/scattering method, the particle size distribution is measured by measuring the angular change in the intensity of the light scattered when the laser light passes through the dispersed particle sample. From this, when the resin emulsion to be measured has an adsorption protective layer or a water-soluble protective colloid on the surface of the particles, the laser beam passes through the adsorption protective layer or the protective colloid, so that the particle size of only the particles is measured. It seems that there is a tendency to

In this specification and the like, the average particle diameter D _B of the resin emulsion (resin particles contained therein) by the dynamic light scattering method is the average particle diameter of the cumulant method analysis, which is measured by the dynamic light scattering method. Means When a particle that is in Brownian motion in a solution or suspension is irradiated with laser light, the scattered light from the particle fluctuates according to the diffusion coefficient. Since large particles move slowly, the fluctuation of the scattered light intensity is gentle, while small particles move fast, and the fluctuation of the scattered light intensity changes rapidly. In the dynamic light scattering method, the fluctuation of scattered light that reflects this diffusion coefficient is detected, the particle diameter is measured using the Stokes-Einstein equation, etc., and the average particle diameter is calculated by the cumulant method. As described above, in the dynamic light scattering method, fluctuations corresponding to the velocity of Brownian motion of particles are observed, and therefore, when the resin emulsion to be measured has an adsorption protective layer or a water-soluble protective colloid on the surface of the particles, those It is considered that there is a tendency that the particle size including is measured.

Due to the difference in the measurement principle between the laser diffraction/scattering method and the dynamic light scattering method as described above, the above D _A /D _B of the resin emulsion is related to the mechanical stability of the resin emulsion, It is considered that it could be used as an index for evaluating the quality.

In the first measurement step S11 in this evaluation method, the average particle diameter D _A of the resin emulsion is measured by the laser diffraction/scattering method. In the second measurement step S12, the average particle diameter D _B of the resin emulsion is measured by the dynamic light scattering method. In FIG. 1, the second measurement step S12 is shown after the first measurement step S11, but the order of the first measurement step S11 and the second measurement step S12 is not limited, and the second measurement step S12 is not limited. S12 may be performed before the first measurement step S11, and the first measurement step S11 and the second measurement step S12 may be performed simultaneously (in parallel).

These average particle diameters D _A and D _B can be measured according to a conventional method, and the pH of the resin emulsion is 25° C. and the pH of the D _A measurement is the same as that of the D _B measurement ( The value measured under the condition of the same value ±0.1) can be taken. The pH under these measurement conditions is preferably in the range of 6.5 to 9.5, more preferably in the range of 7.0 to 9.0, and further preferably in the range of 7.5 to 8.5. Is. Particularly preferably, D _A and D _B can take the values measured under the condition that the pH of the resin emulsion is 8. The average particle diameter D _A of the resin emulsion is measured by using a particle size distribution measuring apparatus using a laser diffraction/scattering method (for example, trade name “laser diffraction type nano particle size distribution measuring apparatus SALD-7100”, manufactured by Shimadzu Corporation). , D ₅₀ . In addition, the average particle diameter D _B of the resin emulsion is determined by using a particle size distribution measuring device utilizing a dynamic light scattering method (for example, trade name “concentrated particle size analyzer FPAR-1000”, manufactured by Otsuka Electronics Co., Ltd.). It can be measured by method analysis.

In this evaluation method, usually, before the first measurement step S11 and the second measurement step S12, a resin emulsion as a target for which the average particle diameters D _A and D _B are measured in those steps is prepared. The process (preparation process) is included. In this preparation step, a resin emulsion of a commercially available product obtained by purchase or the like may be prepared, or a prepared resin emulsion may be prepared.

In the calculation step S13 in the present evaluation method, for the resin emulsion, the average particle diameter D _A measured in the first measurement step S11 and the average particle diameter D _B measured in the second measurement step S12 are calculated as a ratio thereof. Calculate a certain D _A /D _B.

The calculation of D _A /D _B in the calculation step S13 may be executed by the information processing device. The information processing device includes, for example, a CPU, a memory, a storage unit, an input unit, an output unit, and the like, and the CPU in the information processing device may cause the calculation of D _A /D _B. For example, a general-purpose computer may be used as the information processing device, or a computer installed in the above-described particle size distribution measuring device may be used. For example, the information processing device and the particle size distribution measuring device may be connected to each other, and the average particle diameters D _A and D _B obtained by the particle size distribution measuring device may be input to the input unit of the information processing device. Then, a program (or software including it) for calculating D _A /D _B from the values of D _A and D _B input to the input unit is stored in a storage unit or a recording medium in the information processing device, The CPU may read and execute the program. Further, the CPU may output the calculated value of D _A /D _{B to} an output unit (monitor) of the information processing device.

In the evaluation step S14 in the present evaluation method, the quality of mechanical stability of the resin emulsion is evaluated based on the value of D _A /D _B obtained in the calculation step S13. As described above, it has been found that a resin emulsion having an adsorption protective layer or a water-soluble protective colloid on the surface of particles tends to have good mechanical stability. A resin emulsion having an adsorption protective layer, a protective colloid, etc. on the surface of the particles has an average particle diameter D _B measured by the dynamic light scattering method more than an average particle diameter D _A measured by the laser diffraction/scattering method. It turned out to be measured as a large value. Therefore, as an example of this evaluation method, when the value of D _A /D _B is less than 1 in the evaluation step S14, it can be determined that the mechanical stability of the resin emulsion is good.

The evaluation of the mechanical stability of the resin emulsion in the evaluation step S14 may be performed by the above-described information processing device (the CPU thereof). For example, it is determined that the mechanical stability is good when the value of D _A /D _B is less than 1, and the mechanical stability is good when the value of D _A /D _B is 1 or more. A program (or software including the program) that is determined not to be stored may be stored in a storage unit or a recording medium of the information processing apparatus, and the CPU may read and execute the program. Furthermore, the CPU may output the result evaluated based on the value of D _A /D _B (result of the mechanical stability of the resin emulsion) to the output unit (monitor) of the information processing device.

In the evaluation step S14, the quality of mechanical stability of the resin emulsion is not limited to the two-level evaluation of “good” and “not good” based on the value of D _A /D _B. You may evaluate in multiple steps of three or more steps.

Next, the resin emulsion to be evaluated in this evaluation method will be described. This evaluation method can be widely applied to resin emulsions because of the tendency shown in the test example described later. The resin particles in the resin emulsion (in this specification, etc., may be simply referred to as “particles”) are monomers having a polymerizable unsaturated bond (hereinafter referred to as “polymerizable monomer”). There are structural units derived from one or more of the above). The resin particles are preferably a copolymer of two or more polymerizable monomers, but may be a homopolymer of one polymerizable monomer.

In the present specification and the like, homopolymerization and copolymerization may be simply referred to as “polymerization” including both without distinction. Further, in the present specification and the like, the “structural unit” means a unit of a polymerizable monomer forming a resin (polymer). The "structural unit derived from (polymerizable monomer)" is, for example, a structure in which a polymerizable double bond (C=C) in the monomer is cleaved to become a single bond (-CC-). A unit etc. are mentioned.

The resin emulsion can be obtained by polymerizing one or more polymerizable monomers (monomer components) that form resin particles in an aqueous medium such as water that is usually contained in the resin emulsion. it can. Further, for example, a resin emulsion can be obtained by post-emulsifying resin particles produced separately from the aqueous medium by a method such as forced emulsification or self-emulsification. The resin emulsion is preferably obtained by emulsion polymerization of a monomer component that forms resin particles in an aqueous medium. Water is suitable as the aqueous medium, and water alone may be used, or a mixed medium of water and an organic solvent may be used. Examples of the organic solvent include, but are not limited to, methanol, ethanol, isopropanol, ethylcarbitol, and N-methylpyrrolidone, and one or more organic solvents may be used. May be.

A resin emulsion containing (meth)acrylic resin particles can be mentioned as a suitable evaluation target in the present evaluation method. In the present specification and the like, the “(meth)acrylic resin particles” are resin particles obtained by polymerizing a monomer component containing at least a (meth)acrylic acid ester as a polymerizable monomer, and at least a (meth)acrylic resin. It has a structural unit derived from an acid ester. In this specification and the like, the term “(meth)acrylic” means that both the terms “acrylic” and “methacrylic” are included. Similarly, the term “(meth)acrylate” means that both the terms “acrylate” and “methacrylate” are included. The (meth)acrylic resin particles may be polymer (homopolymer) particles obtained by polymerizing one type of polymerizable monomer ((meth)acrylic acid ester), or two types containing (meth)acrylic acid ester. It may be a polymer (copolymer) particle obtained by polymerizing (copolymerizing) the above polymerizable monomer.

Examples of the (meth)acrylic acid ester include (meth)acrylic acid alkyl ester, (meth)acrylic acid hydroxyalkyl ester, (meth)acrylic acid alkoxyalkyl ester, (meth)acrylic acid aralkyl ester, and (meth)acrylic acid. Examples thereof include acid aryl esters, and other (meth)acrylic acid esters other than them. One or more of these (meth)acrylic acid esters can be used. Among these, it is preferable that the monomer component forming the (meth)acrylic resin particles contains at least an alkyl ester of (meth)acrylic acid.

Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth). Acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl ( (Meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-undecyl (meth)acrylate, n- Linear or branched chain such as dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate (Meth)acrylic acid alkyl ester having an alkyl group; and cyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl ( Examples thereof include alicyclic (meth)acrylic acid alkyl esters such as (meth)acrylate. One or more of these (meth)acrylic acid alkyl esters can be used. Among these, a (meth)acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 18 (more preferably 1 to 12) carbon atoms is preferable, and methyl (meth)acrylate, and 2-Ethylhexyl (meth)acrylate is more preferred.

Examples of (meth)acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3 -Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate Can be mentioned. These 1 type(s) or 2 or more types can be used.

Examples of the (meth)acrylic acid alkoxyalkyl ester include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, and 2 -Phenoxyethyl (meth)acrylate etc. can be mentioned. These 1 type(s) or 2 or more types can be used.

Examples of the (meth)acrylic acid aralkyl ester include benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, methylbenzyl (meth)acrylate, and naphthylmethyl (meth)acrylate. These 1 type(s) or 2 or more types can be used.

Examples of the (meth)acrylic acid aryl ester include phenyl(meth)acrylate, 4-hydroxyphenyl(meth)acrylate, tolyl(meth)acrylate, and naphthyl(meth)acrylate. These 1 type(s) or 2 or more types can be used.

Examples of other (meth)acrylic acid esters include polyalkylene glycol (meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and methoxy polyethylene glycol mono(meth)acrylate; 2 -(Meth)acrylic acid alkyl ester having a halogen atom such as chloroethyl (meth)acrylate, trifluoroethyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate A (meth)acrylic acid ester having an amino group such as 2-(dimethylamino)ethyl(meth)acrylate, 2-(diethylamino)ethyl(meth)acrylate, and 3-(dimethylamino)propyl(meth)acrylate; carboxy (Meth)acrylic acid ester having a carboxy group such as ethyl (meth)acrylate and carboxypentyl (meth)acrylate; glycidyl (meth)acrylate, glycerin mono (meth)acrylate, 2-methylglycidyl (meth)acrylate, and 3 , (Epoxycyclohexylmethyl (meth)acrylate and other epoxy group-containing (meth)acrylic acid esters and derivatives thereof; 2-sulfoethyl (meth)acrylate and 3-sulfopropyl (meth)acrylate and other sulfonic acid groups (Meth)acrylate; (meth)acrylate having a phosphoric acid group such as 2-(phosphonooxy)ethyl (meth)acrylate; (meth)acrylate having an isocyanate group such as 2-isocyanatoethyl (meth)acrylate; tetrahydrofur (Meth)acrylate having a heterocycle such as furyl(meth)acrylate; methoxypolyethylene glycol (meth)acrylate, and alkyl group or aryl group-terminated polyalkylene glycol mono(meth)acrylate such as phenoxypolyethylene glycol (meth)acrylate Can be mentioned. These 1 type(s) or 2 or more types can be used.

The (meth)acrylic resin particles are resin particles obtained by polymerizing the above-mentioned (meth)acrylic acid ester and a monomer component containing another polymerizable monomer copolymerizable with the (meth)acrylic acid ester. May be. In this case, the (meth)acrylic resin particles have a structural unit derived from a (meth)acrylic acid ester and a structural unit derived from another polymerizable monomer copolymerizable with the (meth)acrylic acid ester. be able to.

As the other polymerizable monomer, an unsaturated carboxylic acid-based monomer is preferable, and the (meth)acrylic resin particles preferably include a structural unit derived from the unsaturated carboxylic acid-based monomer. In the present specification and the like, unsaturated carboxylic acid-based monomers include unsaturated carboxylic acids, and their anhydrides and monoesters.

Examples of unsaturated carboxylic acid-based monomers include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid; maleic anhydride, and itaconic anhydride. And unsaturated carboxylic acid anhydrides; monoesters of unsaturated carboxylic acids such as maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, and itaconic acid monobutyl ester. It is more preferable to use one or more of these unsaturated carboxylic acid monomers. Among these, (meth)acrylic acid is more preferable.

The total content of unsaturated carboxylic acid-based monomers in the monomer component forming the resin particles (content ratio of structural units derived from unsaturated carboxylic acid-based monomers in the resin particles) is It is preferably 30% by mass or less based on the total mass of the formed monomer component. The total content of the unsaturated carboxylic acid-based monomer is more preferably 20% by mass or less, further preferably 15% by mass or less. When an unsaturated carboxylic acid monomer is used for the resin particles, the total content of the unsaturated carboxylic acid monomer is preferably 0.1% by mass or more, It is more preferably 5% by mass or more, and further preferably 1% by mass or more.

Examples of the polymerizable monomer other than the unsaturated carboxylic acid-based monomer include an unsaturated monomer having a nitrogen atom and a styrene-based monomer. Among these, the styrene-based monomer is preferable, and the (meth)acrylic resin particles preferably include a structural unit derived from the styrene-based monomer.

Examples of unsaturated monomers having a nitrogen atom include unsaturated monomers having a cyano group such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth). Acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-[ Acrylamide monomers such as 2-dimethylaminoethyl](meth)acrylamide, N-[3-dimethylaminopropyl](meth)acrylamide, diacetone acrylamide, 4-acryloylmorpholine and 4-methacryloylmorpholine; N-vinyl Acetamide, acetamide-based monomers having a vinyl group such as N-vinyl-N-methylacetamide; N-vinyl-2-pyrrolidone, 4-vinylpyridine, 1-vinylimidazole, 2-vinyl-2-oxazoline, and Examples thereof include nitrogen-containing heterocyclic compounds having a vinyl group such as 2-isopropenyl-2-oxazoline. These 1 type(s) or 2 or more types can be used.

Examples of the styrene-based monomer include styrene, α-methylstyrene, o-, m-, p-methylstyrene, o-, m-, p-ethylstyrene, 4-tert-butylstyrene, o-, m. -, p-hydroxystyrene, o-, m-, p-methoxystyrene, o-, m-, p-ethoxystyrene, o-, m-, p-chlorostyrene, o-, m-, p-bromostyrene , O-, m-, p-fluorostyrene, o-, m-, p-chloromethylstyrene and the like. These 1 type(s) or 2 or more types can be used. Of these, styrene is preferred.

As the other polymerizable monomer, in addition to the above-mentioned unsaturated carboxylic acid-based monomer, a nitrogen atom-containing unsaturated monomer, and a styrene-based monomer, for example, a vinyl-based monomer, unsaturated It is also possible to use alcohols, vinyl ether-based monomers, vinyl ester-based monomers, unsaturated monomers having an epoxy group, unsaturated monomers having a sulfonic acid group, and the like.

Examples of vinyl monomers include vinyl chloride and vinyl fluoride. Examples of unsaturated alcohols include vinyl alcohol and allyl alcohol. Examples of vinyl ether-based monomers include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, phenyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprylate, vinyl laurate, vinyl stearate, and vinyl versatate. Examples of the unsaturated monomer having an epoxy group include allyl glycidyl ether and the like. Examples of the unsaturated monomer having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, and 2-(meth)acrylamido-2-methylpropane sulfonic acid. .. These 1 type(s) or 2 or more types can be used.

Further, for the monomer component forming the resin particles, it is possible to use, as the polymerizable monomer, a monomer capable of functioning as a crosslinking agent (crosslinking monomer). A monomer having two or more polymerizable unsaturated bonds can be used as the crosslinkable monomer. Examples of the crosslinkable monomer include 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4 -Butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, tri Ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth) Acrylate and bifunctional (meth)acrylate such as glycerin di(meth)acrylate; polyfunctional such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate (Meth)acrylate; allyl (meth)acrylate; divinylbenzene; and diallyl phthalate. These 1 type(s) or 2 or more types can be used.

Further, as the crosslinkable monomer, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3- A silane coupling agent such as acryloxypropyltrimethoxysilane may also be mentioned, and it is possible to use one type or two or more types thereof.

The monomer component forming the (meth)acrylic resin particles more preferably contains at least one of the above-mentioned (meth)acrylic acid ester and styrene-based monomer as a main component, and (meth)acrylic acid It is more preferable to contain at least one of an alkyl ester and styrene as a main component.

Here, the “main component” refers to a monomer whose proportion (mass %) in the monomer component forming the resin particles is the largest among the monomer components forming the resin particles. For example, when the monomer component forming the resin particles contains a (meth)acrylic acid ester as a main component, one of the (meth)acrylic acid esters occupying in the monomer component forming the resin particles The proportion (mass %) of the monomer is higher than any proportion (mass %) of the other monomers (monomers other than the above-mentioned one monomer) in the monomer component forming the resin particles. It also means that there are many. When both the above-mentioned (meth)acrylic acid ester ((meth)acrylic acid alkyl ester) and the styrene-based monomer (styrene) are main components, it means that the above-mentioned proportions (% by mass) are equivalent. .. The content of the main component in the monomer component forming the resin particles (content ratio of structural units derived from the main component in the particles) is 30 based on the total mass of the monomer components forming the resin particles. To 90% by mass, preferably 40 to 80% by mass, and more preferably 50 to 70% by mass.

As described above, as a suitable evaluation target in the present evaluation method, a resin emulsion containing (meth)acrylic resin particles can be mentioned, but a resin emulsion described from the following viewpoints is also suitable.

As shown in the test examples below, a resin emulsion effectively having an adsorption protective layer in which a polycarboxylic acid type polymer compound is adsorbed on the surface of particles, or particles (polymer) containing structural units derived from (meth)acrylic acid to some extent. It was found that the resin emulsion that it has had a value of D _A /D _B that was easily less than 1 and that it had good mechanical stability. From this, as the evaluation target, a resin emulsion containing at least one of a resin emulsion containing a polycarboxylic acid type polymer compound; and a resin emulsion containing particles containing a structural unit derived from (meth)acrylic acid; preferable. Furthermore, a resin emulsion that corresponds to at least one of them and contains the above-mentioned (meth)acrylic resin particles is more preferable. That is, a resin emulsion containing (meth)acrylic resin particles and a polycarboxylic acid type polymer compound; and particles containing structural units derived from each of (meth)acrylic acid ester and (meth)acrylic acid ((meth ) A resin emulsion containing acrylic resin particles) is more preferable. Also in those resin emulsions, the monomer component forming the resin particles is at least the above-mentioned (meth)acrylic acid ester (particularly (meth)acrylic acid alkyl ester) and styrene-based monomer (particularly styrene). It is more preferable to contain one of them as a main component.

The polycarboxylic acid type polymer compound is a polycarboxylic acid type polymer compound such as polyacrylic acid and polyacrylic acid salt, and has a structural unit derived from carboxylic acid, or a salt or anhydride thereof. It is a water-soluble polymer compound. Examples of the carboxylic acid include unsaturated carboxylic acids, and examples thereof include (meth)acrylic acid, maleic acid, itaconic acid, and fumaric acid. The polycarboxylic acid type polymer compound may be a homopolymer of one kind of carboxylic acid and salts and anhydrides thereof (hereinafter sometimes referred to as “carboxylic acid etc.”), and two kinds thereof. It may be the above copolymer. In addition, the polycarboxylic acid type polymer compound is a copolymer having a structural unit derived from one or more kinds of carboxylic acid and the like and a structural unit derived from one or more kinds of other monomers. May be Examples of the other monomer include olefins such as ethylene and propylene, vinyl group-containing monomers such as styrene and vinyl acetate, sulfo group-containing monomers such as sulfonic acid and its derivatives, and (meth)acrylamide. The amide group-containing monomer and the like can be mentioned.

The weight average molecular weight (Mw) of the polycarboxylic acid type polymer compound is preferably 1,000 to 5,000,000, more preferably 3,000 or more, and more preferably 5,000 or more. More preferable. On the other hand, from the viewpoint of increasing the viscosity of the resin emulsion due to the decrease in the solubility of the polycarboxylic acid type polymer compound in a liquid medium (water etc.) and suppressing the precipitation of resin particles in the emulsion, The Mw of the molecular compound is preferably 5,000,000 or less, more preferably 1,000,000 or less, and further preferably 200,000 or less. In the present specification, the Mw of the polycarboxylic acid type polymer compound is a value measured by gel permeation chromatography (GPC) using polyethylene glycol (PEG) as a standard substance.

Examples of the polycarboxylic acid type polymer compound include poly(meth)acrylic acid, polymaleic acid, polyitaconic acid, acrylic acid-methacrylic acid copolymer, (meth)acrylic acid-maleic acid copolymer, olefin-maleic acid. Copolymer, olefin-maleic anhydride copolymer, (meth)acrylic acid-sulfonic acid copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer Examples thereof include polymers, acrylamide-(meth)acrylic acid copolymers, and salts thereof, and one or more polycarboxylic acid type polymer compounds can be used. Examples of the salt include metal salts, ammonium salts, organic amine salts and the like. Examples of the metal atom in the metal salt include alkali metals such as sodium and potassium, Group 2 elements such as calcium and magnesium, iron, and aluminum. Examples of the organic amine salt include alkylamine salts such as methylamine salt and ethylamine salt, and alkanolamine salts such as monoethanolamine salt, diethanolamine salt and triethanolamine salt. As the polycarboxylic acid type polymer compound, one or more kinds selected from the group consisting of polycarboxylic acid type polymer surfactants, polyacrylic acid, and polyacrylic acid salts such as sodium polyacrylate are used. Is more preferable.

It is also possible to use a commercially available polycarboxylic acid type polymer compound. Commercially available products include, for example, Kao's trade name "Demol" series and "Poise" series, Nippon Shokubai's trade name "Aquaric" series, Daiichi Kogyo Seiyaku's trade name "Sharoll" series, In addition, the product name “JULIMER” series manufactured by Toagosei Co., Ltd. and the like can be mentioned.

<Resin emulsion>
In the course of studying the method for evaluating the mechanical stability of the resin emulsion of one embodiment of the present invention described in detail above, a resin emulsion having a constitution in which mechanical stability is better was found, so that the resin emulsion Will be described below. The resin emulsion described below is also preferable as an evaluation target in the method for evaluating the mechanical stability of the resin emulsion according to the embodiment of the present invention described above.

The resin emulsion of one embodiment of the present invention contains resin particles corresponding to at least one of the following resin particles (I) and (II). The monomer component in the resin particles (I) and (II) is the same as the monomer component described in the evaluation method described above, and one or two kinds of the polymerizable monomers described above. Including the above. The polycarboxylic acid type polymer compound in the resin particles (I) is the same as the polycarboxylic acid type polymer compound described in the above evaluation method.
-Resin particles (I): Resin particles including particles obtained by polymerizing a monomer component and an adsorption protection layer in which a polycarboxylic acid type polymer compound is adsorbed on the surface of the particles.
Resin particles (II): Resin particles obtained by polymerizing a monomer component containing (meth)acrylic acid.

Further, in the resin emulsion of the present embodiment, the ratio D _A /D _B of the average particle size D _A by the laser diffraction/scattering method and the average particle size D _B by the dynamic light scattering method is less than 1. Further, this resin emulsion has an absolute value of the difference between the zeta potential and the zeta potential measured under the same conditions with respect to an equivalent reference emulsion except that the polycarboxylic acid type polymer compound and (meth)acrylic acid are not contained. At 10 mV or more.

This resin emulsion contains resin particles corresponding to at least one of the above resin particles (I) and (II), has D _A /D _B of less than 1, and has a zeta potential of the standard emulsion. Since the absolute value of the difference from the zeta potential is 10 mV or more, the mechanical stability is better. Hereinafter, since D _A /D _B tends to be less than 1 and the zeta potential is likely to be 10 mV or more in absolute value of the difference from the zeta potential of the reference emulsion, the resin stability is preferably a preferable resin emulsion. The configuration of will be described.

The resin emulsion preferably contains at least resin particles corresponding to the resin particles (I), and more preferably contains resin particles corresponding to both the resin particles (I) and (II). preferable. The resin particles corresponding to both the above resin particles (I) and (II) are particles in which a monomer component containing (meth)acrylic acid is polymerized, and a polycarboxylic acid type polymer compound is adsorbed on the surface of the particles. Resin particles including the adsorption protection layer. The resin particles (I) and (II) are preferably the above-mentioned (meth)acrylic resin particles. Therefore, the monomer component in the resin particles (I) and (II) preferably contains at least the above-mentioned (meth)acrylic acid ester, and more preferably contains the above-mentioned (meth)acrylic acid alkyl ester.

The monomer component in the resin particles (I) and (II) more preferably contains at least one of the above-mentioned (meth)acrylic acid ester and styrene-based monomer as a main component, and a (meth)acrylic acid alkyl ester. It is particularly preferable to contain at least one of styrene and styrene as a main component.

When the monomer component in the resin particles (I) and (II) contains (meth)acrylic acid ester as a main component, the total content of the (meth)acrylic acid ester in the monomer component ((meth ) The total content of structural units derived from acrylate ester) is preferably 50% by mass or more (50 to 100% by mass) based on the total mass of the monomer components, and 50 to 99% by mass. It is more preferable that the amount is 60 to 99% by mass.

When the monomer component in the resin particles (I) and (II) contains a styrene-based monomer as a main component, the total content of the styrene-based monomer in the monomer component (the styrene-based monomer in the resin particle) The total content of structural units derived from the monomer) is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and more preferably 50 to 50% by mass, based on the total mass of the monomer components. It is more preferably 70% by mass. Further, the monomer component in this case preferably contains a (meth)acrylic acid ester in addition to the styrene-based monomer as the main component. In that case, the total content of the (meth)acrylic acid ester in the monomer component (the total content of the structural units derived from the (meth)acrylic acid ester in the particles) may be 9 to 60% by mass. It is more preferably from 10 to 50% by mass, further preferably from 20 to 45% by mass.

The monomer component in the resin particles (I) and (II) preferably further contains the above-mentioned unsaturated carboxylic acid-based monomer. The total content of unsaturated carboxylic acid-based monomers in the monomer component forming the resin particles (content ratio of structural units derived from unsaturated carboxylic acid-based monomers in the resin particles) is It is preferably 30% by mass or less based on the total mass of the formed monomer component. The total content of the unsaturated carboxylic acid-based monomer is more preferably 20% by mass or less, further preferably 15% by mass or less. When an unsaturated carboxylic acid monomer is used for the resin particles, the total content of the unsaturated carboxylic acid monomer is preferably 0.1% by mass or more, It is more preferably 5% by mass or more, and further preferably 1% by mass or more. Note that (meth)acrylic acid is particularly preferable as the unsaturated carboxylic acid-based monomer, and the resin emulsion in that case contains at least resin particles corresponding to the above resin particles (II).

Regarding the resin particles (I), by adsorbing the polycarboxylic acid type polymer compound on the surface of the particles by polymerizing the monomer component forming the particles in the presence of the polycarboxylic acid type polymer compound. A protective layer can be formed. Compared with the method of separately blending the polycarboxylic acid type polymer compound with the emulsion containing the resin particles polymerized in the absence of the polycarboxylic acid type polymer compound, the presence of the polycarboxylic acid type polymer compound In the case of the resin particles polymerized by, the polycarboxylic acid type polymer compound is used for stabilizing the synthesis of the resin particles, like the micelle formation in the emulsifier, and the polycarboxylic acid type polymer compound is present on the particle surface. It is thought to be adsorbed efficiently.

From the viewpoint of easily obtaining a resin emulsion having an adsorption protection layer, the resin particles in the emulsion are 0.1 to 20 parts by mass of polycarboxylic acid based on 100 parts by mass of the total amount of the monomer components forming the particles. It is preferable that the monomer component is polymerized in the presence of the type polymer compound. The amount of the polycarboxylic acid type polymer compound used is more preferably 0.2 part by mass or more. On the other hand, from the viewpoint of suppressing the production cost, the amount of the polycarboxylic acid type polymer compound used is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and 10 parts by mass or less. Is more preferable.

The resin particles (II) can be obtained by polymerizing a monomer component containing (meth)acrylic acid. When the resin emulsion contains resin particles corresponding to the above resin particles (II) but does not correspond to the above resin particles (I), the (meth)acryl in the monomer component forming the resin particles The content of the acid (content ratio of the structural unit derived from (meth)acrylic acid in the resin particles) is 1.5% by mass or more based on the total mass of the monomer components forming the resin particles. Is preferred and 2% by mass or more is more preferred.

D _{A /} D _B and the average particle diameter D _A by a laser diffraction scattering method, the ratio of the average particle diameter D _B by a dynamic light scattering method of the resin emulsion of the present embodiment (resin particles) 1 (1 It is less than 0.000, preferably 0.99 or less, and more preferably 0.98 or less. Further, the lower limit of D _A /D _B is not particularly limited, but from the viewpoint of manufacturing the resin emulsion (resin particles), it is preferably 0.2 or more, more preferably 0.3 or more, and 0 It is more preferably 0.35 or more.

As described above, the zeta potential of the resin emulsion of the present embodiment is 10 mV or more in absolute value of the difference from the zeta potential measured under the same conditions for the reference emulsion. The zeta potential is defined as the potential of the water phase surface (sliding surface) that is moved by the resin particles in the emulsion. In this specification and the like, the zeta potential is a value measured for the emulsion when the pH of the emulsion is adjusted to 8±0.1, the temperature is adjusted to 25° C., and the solid content is adjusted to 55% by mass. Can be used for measurement.

If the absolute value of the difference between the zeta potential of the resin emulsion and the zeta potential of the reference emulsion is 10 mV or more, the absolute value of the zeta potential of the resin emulsion may be lower than the absolute value of the zeta potential of the reference emulsion. May be. In general, the zeta potential of an emulsion is greatly affected by the ionic emulsifier contained in the emulsion, while the absolute value of the zeta potential of the emulsion can decrease when an electrically neutral polymer is added to the emulsion. This is because it is considered that there is a property. In the above case, it is considered that the absolute value of the zeta potential of the emulsion may be decreased.As a result of the particles in the emulsion adsorbing the polymer, the aqueous phase that moves along with the particles becomes thicker and determines the zeta potential. This is because the “slip surface” is considered to be farther from the particle surface. The absolute value of the difference between the zeta potential of the resin emulsion and the zeta potential of the reference emulsion is preferably 12 mV or higher, more preferably 15 mV or higher, and preferably 150 mV or lower.

As described above, the reference emulsion is an equivalent emulsion except that it does not contain any of the polycarboxylic acid type polymer compound and the (meth)acrylic acid, as compared with the resin emulsion of the present embodiment which is a comparison target. .. This reference emulsion is obtained by the same production method as the resin emulsion to be compared, except that neither the polycarboxylic acid type polymer compound nor the (meth)acrylic acid is used. Therefore, the reference emulsion and the resin emulsion to be compared have the same monomer component forming particles. Specifically, when the resin emulsion to be compared contains the resin particles corresponding to the resin particles (I) but not the resin particles (II), the resin emulsion and the reference emulsion Means that the monomer components forming the particles are the same. Moreover, when the resin emulsion to be compared contains at least the resin particles corresponding to the resin particles (II), the resin emulsion and the reference emulsion have the same glass transition temperature of the resin (particles). As described above, the monomer components forming the particles are the same except that the (meth)acrylic acid content is replaced with another monomer.

For example, when the resin particles in the resin emulsion to be compared include a structural unit derived from (meth)acrylic acid and a structural unit derived from another monomer (for example, (meth)acrylic acid ester) (in other words, The reference emulsion of (when (meth)acrylic acid and other monomers are used as the monomer component forming the resin particles) is as follows. That is, the reference emulsion in this case has the same total amount of the monomer components forming the resin particles as compared with the comparison resin emulsion, and (meth)acrylic acid used in the comparison resin emulsion. It was obtained in the same manner except that the component was replaced with another monomer so that the resin (particles) had the same glass transition temperature.

The average particle diameter D _B of the resin emulsion (resin particles) measured by the dynamic light scattering method is preferably 25 to 1000 nm, more preferably 35 to 600 nm, and further preferably 45 to 400 nm. The average particle diameter D _A by a laser diffraction scattering method of the resin emulsion (resin particles) in the condition that the ratio D _{A /} D _B against D _B is less than 1, preferably within the above range.

The glass transition temperature (Tg) of the resin particles in the resin emulsion is not particularly limited, but is preferably -50 to 100°C. In the present specification, the Tg of the resin particles is a value measured by DSC when the resin particles are homopolymers. When the resin particles are a copolymer, the Tg of the resin particles is a theoretical value obtained from the following FOX equation using the Tg of the homopolymer.
_{1 / Tg = W 1 / Tg} 1 + W 2 / Tg 2 + ··· W n / Tg n
In the above formula, Tg represents the glass transition temperature (unit: K) of a polymer (copolymer) of n kinds of monomer components (monomers 1 to n). W ₁ , W ₂ ,... W _n represent the mass fraction of each monomer (1, 2,... N) with respect to the total amount of n kinds of monomer components, and Tg ₁ , Tg ₂ , · · · Tg _n are each monomer (1, 2, · · · n) a glass transition temperature of a homopolymer (unit: K) representing the. For example, taking the monomers used in the test examples described below as an example, the glass transition temperature of the homopolymer of the monomers is as follows, and those values are the resins produced in the test examples described below. It was used to calculate the Tg of the particles.
Styrene (ST): 100°C
2-Ethylhexyl acrylate (2EHA): -70°C
Methyl methacrylate (MMA): 105°C
Acrylic acid (AAc): 105°C

The resin particles in the resin emulsion may be particles having a core part and a shell part. When the resin particles are in such a form, the mechanical stability of the resin emulsion may be better. When the resin particles have a core portion and a shell portion, the core portion and the shell portion may be completely compatible with each other and may have a homogeneous structure indistinguishable from each other. It may be a core-shell composite structure or a microdomain structure that is formed uniformly. Among these structures, the core/shell composite structure is preferable in order to bring out the characteristics of the resin particles sufficiently and to manufacture stable resin particles. In the above core/shell composite structure, it is preferable that the surface of the core portion is covered with the shell portion. In this case, the surface of the core portion is preferably completely covered with the shell portion, but may not be completely covered, for example, in the form of a mesh-like coating or in some places the core portion. The part may be exposed. When the resin particles in the resin emulsion correspond to the above-mentioned resin particles (I) and have a core part and a shell part, if the adsorption protective layer is formed on the surface of the particles (shell part), the polycarboxylic acid type high The molecular compound may be used during polymerization of the core part, may be used during polymerization of the shell part, or may be used for both of them. Further, when the resin particles in the resin emulsion correspond to the above-mentioned resin particles (II) and have a core portion and a shell portion, (meth)acrylic acid is preferably used for at least the shell portion.

(Method for producing resin emulsion)
As the method for producing the resin emulsion of the present embodiment, as described above, in the aqueous medium such as water usually contained in the resin emulsion, one or more polymerizable monomers (single monomer) that form the resin particles are used. A method of obtaining a resin emulsion by emulsion polymerization of a monomer component) is preferable. In this method, when a resin emulsion containing the above-mentioned resin particles (I) is obtained, a method of emulsion-polymerizing a monomer component in the presence of the above-mentioned polycarboxylic acid type polymer compound can be used. Further, in the case of obtaining a resin emulsion containing the above-mentioned resin particles (II), a method of emulsion-polymerizing a monomer component containing (meth)acrylic acid can be used.

Specific examples of the emulsion polymerization method include the following methods. That is, an aqueous medium, a monomer component, a polymerization initiator and the like, and in the case of obtaining the above-mentioned resin particles (I), a method in which a polycarboxylic acid type high molecular compound is further mixed and emulsion-polymerized is mentioned. it can. In addition, emulsion polymerization is carried out using a monomer emulsion (pre-emulsion) further containing a polycarboxylic acid type polymer compound when obtaining the above-mentioned resin particles (I) as well as the aqueous medium and the monomer components. A method can be mentioned. Furthermore, an aqueous medium, or a mixed solution containing an aqueous medium and a polycarboxylic acid type polymer compound in the case of obtaining the resin particles (I), and a pre-emulsion containing an aqueous medium and a monomer component are used. A method of emulsion polymerization can be mentioned.

More specifically, a pre-emulsion prepared by previously mixing an aqueous medium, a monomer component and the like, and further in the case of obtaining the resin particles (I), a polymerization initiator, and a polymerization initiator. It is preferable that each of and is dropped into an aqueous medium prepared separately, and the monomer component is polymerized in the aqueous medium to synthesize the resin particles. Further, in the aqueous medium, or in the case of obtaining the resin particles (I), in a mixed solution containing the aqueous medium and the polycarboxylic acid type polymer compound, a pre-emulsion containing the aqueous medium and a monomer component, It is also preferable to add dropwise a polymerization initiator and polymerize the monomer component in an aqueous medium to synthesize the resin particles.

When producing a resin emulsion (when synthesizing resin particles in a resin emulsion), polymerization conditions such as a polymerization temperature and a polymerization time, types and amounts of a polymerization initiator and an emulsifier used, and the like are conventionally known emulsion polymerizations. It can be appropriately determined within the same range as.

For example, the polymerization conditions such as the polymerization temperature and the polymerization time can be appropriately determined according to the type of the monomer used, the polymerization initiator, and the like, the amount used, and the like. For example, the polymerization temperature is preferably in the range of about 20 to 100°C, more preferably in the range of about 40 to 90°C, and the polymerization time is preferably in the range of about 1 to 15 hours. Further, the above-mentioned pre-emulsion and the method of adding (dripping) the polymerization initiator are not particularly limited, and for example, a batch addition method, a continuous addition method, a multi-step addition method and the like can be adopted. May be appropriately combined.

Examples of the polymerization initiator include persulfates, organic peroxides, peroxides such as hydrogen peroxide, and azo compounds. One or more polymerization initiators may be used. You can Also, one or more reducing agents may be used as a redox polymerization initiator used in combination with a peroxide or as a polymerization accelerator.

Specific examples of the persulfate include potassium persulfate, sodium persulfate, ammonium persulfate and the like. Specific examples of the organic peroxides include diacyl peroxides such as benzoyl peroxide and dilauroyl peroxide, dialkyl peroxides such as t-butylcumyl peroxide and dicumyl peroxide, and t-butylperoxylaurate. And peroxyesters such as t-butylperoxybenzoate, and hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide. Specific examples of the azo compound include 2,2'-azobis(2-amidinopropane) dihydrochloride and 4,4'-azobis(4-cyanopentanoic acid). Specific examples of the reducing agent include ascorbic acid and salts thereof, tartaric acid and salts thereof, sulfurous acid and salts thereof, bisulfite and salts thereof, thiosulfuric acid and salts thereof, and iron (II) salts.

When synthesizing the resin particles, a known chain transfer agent may be used to adjust the molecular weight of the resin particles. As the chain transfer agent, for example, hexyl mercaptan, lauryl mercaptan, octyl mercaptan, and alkyl mercaptans such as n- or t-dodecyl mercaptan can be used.

An emulsifier (surfactant) can be used when synthesizing the resin particles in an aqueous medium. Examples of the emulsifier include anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants, and one or more emulsifiers can be used. As the emulsifier, an anionic surfactant and a nonionic surfactant are preferable, and an anionic surfactant is more preferable.

Examples of the anionic surfactant include fatty acid salts such as sodium stearate; alkyl sulfate ester salts such as sodium lauryl sulfate; polyoxyalkylene alkyl ether sulfate salts such as sodium polyoxyethylene alkyl ether sulfate; dodecylbenzene sulfonic acid. Alkylbenzene sulfonates such as sodium; sodium dialkylsulfosuccinate; sodium alkyl diphenyl ether disulfonate; and reactive anionic surfactants such as polyoxyalkylene alkenyl ether ammonium sulfate and polyoxyethylene styrenated propenyl phenyl ether ammonium sulfate You can Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyalkylene derivatives such as polyoxyalkylene alkyl ether; Examples thereof include reactive nonionic surfactants such as oxyalkylene alkenyl ethers and polyoxyethylene styrenated propenyl phenyl ether.

When producing a resin emulsion, it is preferable to polymerize a monomer component to obtain resin particles, and then neutralize with a neutralizing agent. When the resin particles have a carboxy group, it is preferable to neutralize the carboxy group with a basic neutralizing agent. The neutralization will stabilize the emulsion. The neutralizing agent is not particularly limited, and examples thereof include alkali metal compounds such as sodium hydroxide and potassium hydroxide; alkaline earth metal compounds such as calcium hydroxide and calcium carbonate; ammonia; monomethylamine, dimethylamine, trimethylamine, Examples thereof include organic amines such as monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, and diethylenetriamine. One kind or two or more kinds can be used.

The pH of the resin emulsion is not particularly limited, but is preferably 6.0 to 10.0, more preferably 6.5 to 9.5, and further preferably 7.0 to 9.0. preferable. In the present specification, the pH of the resin emulsion can be a value measured in accordance with JIS K6833-1:2008 and is a value at 25°C.

The non-volatile content (solid content) of the resin emulsion is preferably 30 to 75% by mass, more preferably 35 to 70% by mass, and 40 to 65% by mass, based on the total mass of the resin emulsion. Is more preferable. In the present specification, the non-volatile content (solid content) of the resin emulsion can take a value measured in accordance with the regulations of JIS K6833-1:2008.

The viscosity of the resin emulsion at 25° C. is preferably 50 mPa·s or more, more preferably 100 mPa·s or more, still more preferably 150 mPa·s or more. From the viewpoint of handling, the viscosity of the resin emulsion at 25° C. is preferably 10,000 mPa·s or less, more preferably 6000 mPa·s or less, and further preferably 4000 mPa·s or less. In the present specification, the viscosity of the resin emulsion at 25° C. can be a value measured according to JIS K6833-1:2008.

The resin emulsion may contain one kind or two or more kinds of the above-mentioned resin particles, and may contain various additives as required. Examples of the additive include colorants such as pigments and dyes, metal compounds, solvents, plasticizers, dispersants, surfactants, foaming agents, lubricants, gelling agents, film-forming aids, antifreezing agents, and crosslinking agents. , PH adjuster, viscosity adjuster, antiseptic, antifungal agent, bactericide, rust inhibitor, flame retardant, wetting agent, defoaming agent, antioxidant, antiaging agent, ultraviolet absorber, stabilizer, antistatic agent Agents, antiblocking agents and the like.

As described in detail above, the resin emulsion mechanical stability evaluation method and the resin emulsion of one embodiment of the present invention can have the following configurations.
[1] _A first measuring step of measuring an average particle diameter D _A of the resin emulsion by a laser diffraction/scattering method, and a second measuring step of measuring an average particle diameter D _B of the resin emulsion by a dynamic light scattering method. And a calculation step of calculating the ratio D _A /D _B from the measured average particle size D _A and the measured average particle size D _B , and based on the value of D _A /D _B , An evaluation step of evaluating the mechanical stability of a resin emulsion, and a method for evaluating the mechanical stability of a resin emulsion.
[2] The resin emulsion machine according to the above [1], wherein in the evaluation step, when the value of D _A /D _B is less than 1, it is determined that the mechanical stability of the resin emulsion is good. Stability evaluation method.
[3] The method for evaluating mechanical stability of a resin emulsion according to the above [1] or [2], wherein the resin emulsion is a resin emulsion containing (meth)acrylic resin particles.
[4] The resin emulsion is a resin emulsion corresponding to at least one of a resin emulsion containing a polycarboxylic acid type polymer compound; and a resin emulsion containing particles containing a structural unit derived from (meth)acrylic acid. The method for evaluating the mechanical stability of the resin emulsion according to any one of [1] to [3] above.
[5] Resin particles (I) containing particles in which a monomer component is polymerized and an adsorption protective layer in which a polycarboxylic acid type polymer compound is adsorbed on the surface of the particles, and a single amount containing (meth)acrylic acid containing resin particles corresponding to at least one of resin particles body components are polymerized (II), the ratio between the average particle diameter D _B according to the mean particle diameter D _a and a dynamic light scattering method by laser diffraction scattering method D _a / D _B is less than 1, the difference between the zeta potential zeta potential, wherein the polycarboxylic acid type polymer compound and the (meth) except that it does not contain acrylic acid, which is measured under the same conditions for equivalent standards emulsion A resin emulsion having an absolute value of 10 mV or more.

Hereinafter, further specific examples of the above-described embodiment will be described with reference to test examples, but the present invention is not limited thereto.

<Production of resin emulsion>
(Test Example 1)
A four-necked separable flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel was charged with 31.2 parts by mass of deionized water, and the internal temperature was raised to 80°C while stirring.
On the other hand, separately from the separable flask, 44.5 parts by mass of 2-ethylhexyl acrylate (hereinafter, "2EHA"), 54.3 parts by mass of methyl methacrylate (hereinafter, MMA), and acrylic acid (hereinafter, "AAc") Monomer component consisting of 1.2 parts by mass (total amount: 100.0 parts by mass), t-dodecyl mercaptan: 0.8 parts by mass, sodium polyoxyethylene alkyl ether sulfate as an anionic emulsifier 1.0 part by mass (Kao Corporation) Product name "Latemur WX" (solid content 26% by mass) 3.9 parts by mass), polycarboxylic acid type polymer compound 3.0 parts by mass (with Kaosha's special polycarboxylic acid type polymer surfactant) One brand name "Demol EP" (solid content 25% by mass) 12.0 parts by mass; hereinafter, "polycarboxylic acid type polymer (a)") and deionized water 38.6 parts by mass are emulsified with a homodisper. Then, a pre-emulsion was prepared.
Next, while maintaining the internal temperature in the separable flask at 80° C., the prepared pre-emulsion was uniformly added dropwise from the dropping funnel to the deionized water in the separable flask over 3 hours. At the same time, 3.0 parts by mass of a 10% by mass ammonium persulfate aqueous solution was uniformly added dropwise over 3 hours. After the completion of dropping, the mixture was aged at 80° C. for 3 hours, cooled, and then neutralized by adding 1.0 part by mass of 25% by mass ammonia water. After adjusting the pH, the mixture was filtered using a 120-mesh filter cloth to obtain a resin emulsion. Thus, by polymerizing the monomer component whose main component is a (meth)acrylic acid alkyl ester in the presence of the polycarboxylic acid type polymer (a), the polycarboxylic acid type polymer (( A resin emulsion containing (meth)acrylic resin particles having an adsorption protection layer to which a) was adsorbed was obtained. The Tg (theoretical value) of the resin particles in this resin emulsion is 0°C.

(Test Examples 2 to 6)
In Test Examples 2 to 6, the particle surface was prepared by the same method as in Test Example 1 except that the amount of the polycarboxylic acid type polymer (a) used in Test Example 1 was changed as compared with Test Example 1. A resin emulsion having an adsorption protection layer of the polycarboxylic acid type polymer (a) was obtained. In Test Example 2, 0.2 parts by mass of the polycarboxylic acid type polymer (a) (0.8 parts by mass of "Demol EP" (solid content 25% by mass)) was used. In Test Example 3, 0.5 part by mass of the polycarboxylic acid type polymer (a) (2.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used. In Test Example 4, 5.0 parts by mass of the polycarboxylic acid type polymer (a) (20.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used. In Test Example 5, 10.0 parts by mass of the polycarboxylic acid type polymer (a) (40.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used. In Test Example 6, 15.0 parts by mass of the polycarboxylic acid type polymer (a) (60.0 parts by mass of the product name "Demole EP" (solid content 25% by mass)) was used.

(Test Examples 7 to 9)
In Test Examples 7 to 9, as compared with Test Example 1, except that the polycarboxylic acid type polymer (a) used in Test Example 1 was changed to another polycarboxylic acid type polymer compound, By the same method, a resin emulsion having an adsorption protection layer of a polycarboxylic acid type polymer compound on the particle surface was obtained. In Test Example 7, as a polycarboxylic acid type polymer compound, 3.0 parts by mass of sodium polyacrylate (trade name “Aqualic DL-40” manufactured by Nippon Shokubai Co., Ltd. (solid content: 40% by mass)) was used. )It was used. Hereinafter, the sodium polyacrylate used in Test Example 7 may be referred to as “polycarboxylic acid type polymer (b)”. In Test Example 8, as the polycarboxylic acid type polymer compound, 3.0 parts by mass of sodium polyacrylate (7.5 parts by mass of Kao's trade name "Poise 520" (solid content 40% by mass)) was used. .. Hereinafter, the sodium polyacrylate used in Test Example 8 may be referred to as “polycarboxylic acid type polymer (c)”. In Test Example 9, as a polycarboxylic acid-type polymer compound, sodium polyacrylate 3.0 parts by mass (trade name “Aqualic DL-453” manufactured by Nippon Shokubai Co., Ltd. (solid content 35% by mass) 8.6 parts by mass) )It was used. Hereinafter, the sodium polyacrylate used in Test Example 9 may be referred to as “polycarboxylic acid type polymer (d)”.

(Test Examples 10 and 11)
In Test Examples 10 and 11, the resin was prepared in the same manner as in Test Example 1 except that the amounts of MMA and AAc used in the monomer component were changed and that the polycarboxylic acid type polymer compound was not used. An emulsion was obtained. In Test Example 10, a monomer component composed of 24.5 parts by mass of 2EHA, 53.0 parts by mass of MMA, and 2.5 parts by mass of AAc (total amount: 100.0 parts by mass) was used. In Test Example 11, 44.5 parts by mass of 2EHA, 50.5 parts by mass of MMA, and 5.0 parts by mass of AAc (a total amount of 100.0 parts by mass) were used.

(Test Example 12)
In Test Example 12, as compared with Test Example 1, a resin emulsion was obtained in the same manner as in Test Example 1 except that the polycarboxylic acid type polymer (a) was not used.

(Test Example 13)
In Test Example 13, a resin emulsion was prepared in the same manner as in Test Example 1 except that the amount of the polycarboxylic acid type polymer (a) used in Test Example 1 was changed as compared with Test Example 1. Obtained. In Test Example 13, 0.05 part by mass of the polycarboxylic acid type polymer (a) (0.2 part by mass of "Demol EP" (solid content 25% by mass)) was used.

(Test Example 14)
First, the same resin emulsion as in Test Example 12 was prepared. That is, a resin emulsion was produced in the same manner as in Test Example 1 except that the polycarboxylic acid type polymer (a) used in Test Example 1 was not used. Next, to the obtained resin emulsion, 3.0 parts by mass of the polycarboxylic acid type polymer (a) (12.0 parts by mass of the product name "Demol EP" (solid content 25% by mass)) was added. Thus, in Test Example 14, after producing a resin emulsion containing resin particles polymerized in the absence of a polycarboxylic acid type polymer compound, the resin emulsion was added to 100 parts by mass of the monomer component. As a result, a resin emulsion containing 3 parts by mass of the polycarboxylic acid type polymer (a) was obtained.

(Test Example 15)
In Test Example 15, as compared with Test Example 1, AAc in the monomer component was not used, the amount of MMA used was increased accordingly, and the polycarboxylic acid type polymer (a) was not used. A resin emulsion was obtained in the same manner as in Test Example 1 except for the above. In Test Example 15, 44.5 parts by mass of 2EHA and 55.5 parts by mass of MMA (a total amount of 100.0 parts by mass) were used. In this way, a resin emulsion equivalent to the resin emulsions obtained in Test Examples 1 to 14 was produced except that the polycarboxylic acid type polymer compound and acrylic acid were not included. The resin emulsion obtained in Test Example 15 was used as a reference emulsion used for evaluation of the zeta potential described later in the resin emulsion obtained in Test Examples 1 to 15.

(Test Example 16)
A four-necked separable flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel was charged with 31.2 parts by mass of deionized water, and the internal temperature was raised to 80°C while stirring.
On the other hand, in addition to the separable flask, a monomer component composed of 55.0 parts by mass of styrene (hereinafter, “ST”), 43.8 parts by mass of 2EHA, and 1.2 parts by mass of AAc (total amount: 100.0 parts by mass). , And 0.8 parts by mass of t-dodecyl mercaptan, 1.0 part by mass of sodium polyoxyethylene alkyl ether sulfate as an anionic emulsifier (trade name “Latemur WX” manufactured by Kao Corporation (solid content 26% by mass)) 3.9 parts by mass Part), 0.2 parts by mass of the polycarboxylic acid type polymer (a) (0.8 parts by mass of "Demol EP" (solid content 25% by mass)), and 38.6 parts by mass of deionized water. A pre-emulsion was prepared by emulsifying with a disper.
Next, while maintaining the internal temperature in the separable flask at 80° C., the prepared pre-emulsion was uniformly added dropwise from the dropping funnel to the deionized water in the separable flask over 3 hours. At the same time, 3.0 parts by mass of a 10% by mass ammonium persulfate aqueous solution was uniformly added dropwise over 3 hours. After the completion of the dropping, the mixture was aged at 80° C. for 3 hours, cooled, and neutralized by adding 1.0 part by mass of 25% by mass aqueous ammonia. After adjusting the pH, the mixture was filtered using a 120-mesh filter cloth to obtain a resin emulsion. In this manner, by adsorbing the polycarboxylic acid type polymer (a) on the particle surface by polymerizing the monomer component whose main component is styrene in the presence of the polycarboxylic acid type polymer (a). A resin emulsion containing (meth)acrylic resin particles having a protective layer was obtained. The Tg (theoretical value) of the resin particles in this resin emulsion is 0°C.

(Test Examples 17 to 20)
In Test Examples 17 to 20, the particle surface was prepared in the same manner as in Test Example 16 except that the amount of the polycarboxylic acid type polymer (a) used in Test Example 16 was changed as compared with Test Example 16. A resin emulsion having an adsorption protection layer of the polycarboxylic acid type polymer (a) was obtained. In Test Example 17, 0.5 parts by mass of the polycarboxylic acid type polymer (a) (2.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used. In Test Example 18, 1.0 part by mass of the polycarboxylic acid type polymer (a) (4.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used. In Test Example 19, 3.0 parts by mass of the polycarboxylic acid type polymer (a) (12.0 parts by mass of trade name "Demol EP" (solid content 25% by mass)) was used. In Test Example 20, 5.0 parts by mass of the polycarboxylic acid type polymer (a) (20.0 parts by mass of trade name "Demole EP" (solid content 25% by mass)) was used.

(Test Example 21)
In Test Example 21, a resin emulsion was obtained by the same method as in Test Example 16 except that the polycarboxylic acid type polymer (a) was not used, as compared with Test Example 16.

(Test Example 22)
In Test Example 22, a resin emulsion was prepared in the same manner as in Test Example 16 except that the amount of the polycarboxylic acid type polymer (a) used in Test Example 16 was changed as compared with Test Example 16. Obtained. In Test Example 22, 0.05 parts by mass of the polycarboxylic acid type polymer (a) (0.2 parts by mass of trade name "Demoll EP" (solid content 25% by mass)) was used.

(Test Example 23)
In Test Example 23, compared with Test Example 16, AAc in the monomer component was not used, the amount of ST used was increased accordingly, and the polycarboxylic acid type polymer (a) was not used. A resin emulsion was obtained in the same manner as in Test Example 16 except for the above. In Test Example 23, a monomer component consisting of ST56.2 parts by mass and 2EHA43.8 parts by mass (total amount: 100.0 parts by mass) was used. In this way, resin emulsions equivalent to the resin emulsions obtained in Test Examples 16 to 22 were produced except that the polycarboxylic acid type polymer compound and acrylic acid were not contained. The resin emulsion obtained in Test Example 23 was used as a reference emulsion used in the evaluation of the zeta potential described later in the resin emulsion obtained in Test Examples 16 to 23.

<Properties of resin emulsion>
Each of the obtained resin emulsions was adjusted to have a pH of 8 and a nonvolatile content (solid content) of 55.0% by mass. The pH, non-volatile content, and viscosity of each resin emulsion, the average particle diameter D _{A of} each resin emulsion (resin particles contained therein) by the laser diffraction/scattering method, and the average particle diameter D _B by the dynamic light scattering method were measured. It measured as follows.

(PH)
According to JIS K6833-1:2008, the pH of each resin emulsion at 25° C. was measured using a pH meter (trade name “pH meter HM-25R” manufactured by Toa DKK Co., Ltd.).

(Nonvolatile)
Based on JIS K6833-1:2008, the nonvolatile content (solid content) of each resin emulsion was measured under the conditions of a drying temperature of 140° C. and a drying time of 0.5 hour.

(viscosity)
According to JIS K6833-1:2008, the viscosity of each resin emulsion was measured under the conditions of a rotation speed of 10 rpm and a temperature of 25° C. using a BH type rotational viscometer (BHII viscometer manufactured by Toki Sangyo Co., Ltd.). It was measured.

(Zeta potential)
Using a high concentration zeta potential measuring device (manufactured by Kyowa Interface Science Co., Ltd.), the stirring speed was set to 250 rpm and the sample temperature was set to 25° C., and the zeta potential (mV) of each resin emulsion was measured. Regarding the zeta potential of the resin emulsions obtained in Test Examples 1 to 15, the absolute value of the difference from the zeta potential (reference) of the resin emulsion (reference emulsion) obtained in Test Example 15 was calculated. Regarding the zeta potential of the resin emulsions obtained in Test Examples 16 to 23, the absolute value of the difference from the zeta potential (reference) of the resin emulsion (reference emulsion) obtained in Test Example 23 was calculated.

(Average particle diameter D _A by laser diffraction/scattering method)
For each resin emulsion (resin particles), a refractive index was measured using a particle size distribution measuring device using a laser diffraction/scattering method (manufactured by Shimadzu Corp., trade name Was 1.45 to 1.00i, the particle diameter (D ₅₀ ; nm) at a cumulative 50% in the volume-based particle size distribution was measured.

(Average particle diameter D _B by dynamic light scattering method)
For each resin emulsion (resin particles), a cumulant method was used by using a particle size distribution measuring device (manufactured by Otsuka Electronics Co., Ltd., trade name "Dense particle size analyzer FPAR-1000") using a dynamic light scattering method and a concentrated probe. The average particle size (nm) was measured by analysis.

<Evaluation of mechanical stability of resin emulsion>
The ratio D _A /D _B of each resin emulsion was calculated from the measured average particle diameters D _A and D _B. D based on the value of the A _/ D _B, denoted as Tables below "○" determines that the mechanical stability of the resin emulsion values of D A _/ D _B was less than 1 is good, D _A A resin emulsion having a value of /D _B of 1 or more was judged to have poor mechanical stability and was marked with “x” in the table below.

(Confirmation test of mechanical stability of resin emulsion)
For each resin emulsion, a test was conducted to confirm the evaluation result of mechanical stability based on the above D _A /D _B. Specifically, 50 g of pure water was added to 100 g of the resin emulsion, sufficiently stirred and mixed, filtered through a 300 mesh wire net, and 100 g of the filtrate was used to test a Marlon mechanical stability tester (Jim Quarts Company). The mechanical stability test was performed using The test conditions were, in accordance with JIS K6828:1996, a scale having a scale of 10 kg, a disk rotation speed of 1000 rpm, a rotation time of 10 minutes, and a test temperature of 25°C. After the test was completed, the aggregate was immediately filtered through a 300 mesh wire net and dried at 110° C. for 1 hour, and the mass of the residue of the aggregate after drying was measured. Then, the aggregation rate was calculated by the following formula. The smaller the value of the aggregation rate, the better the mechanical stability.
Aggregation rate (%)=(mass of residue of aggregate after drying g/100 g)×100

For each resin emulsion, the type and amount of the monomer and polycarboxylic acid type polymer compound used in the production of the resin particles, and the difference between the pH, solid content, viscosity, zeta potential, and zeta potential standard (absolute value) , D _A , D _B , D _A /D _B , and the evaluation results of mechanical stability are shown in Table 1 (Tables 1-1 to 1-3).

From the results of Test Examples 1 to 23, in Test Examples 1 to 11 and Test Examples 16 to 20, resin emulsions having D _A /D _B of less than 1 were obtained, while Test Examples 12 to 15 and Test Examples 21 to 21. In No. 23, a resin emulsion having D _A /D _B of 1 or more was obtained. Then, the D A _/ D _B is less than 1 resin emulsion (Test Examples 1 to 11 and Test Examples 16 to 20), the measured value of the resulting aggregation rate test using Maron mechanical stability tester It was less than 0.001%. On the other hand, in the resin emulsions having D _A /D _B of 1 or more (Test Examples 12 to 15 and Test examples 21 to 23), the measurement of the agglomeration rate obtained in the test using the Marlon mechanical stability tester was measured. The value was 0.01% or more.

Considering that the measured value of the agglomeration rate differs by one digit or more depending on whether D _A /D _B of the resin emulsion is less than 1 or 1 or more, as apparent from the above test results, It can be seen that the value of D _A /D _B correlates with the mechanical stability of the resin emulsion. Therefore, it is recognized that the mechanical stability of the resin emulsion can be evaluated based on the value of D _A /D _B of the resin emulsion.

In the resin emulsions obtained in Test Examples 15 and 23, since the resin particles contained therein had neither a structural unit derived from (meth)acrylic acid nor an adsorption protective layer, D _A /D _B was 1 or more. It is considered that the result was a very high aggregation rate.

In the resin emulsions obtained in Test Examples 12 and 21, the resin particles contained therein did not have an adsorption protective layer, and although the resin emulsion had a structural unit derived from (meth)acrylic acid, its amount was too small. In addition, it is considered that D _A /D _B was 1 or more, resulting in a high aggregation rate.

In the resin emulsions obtained in Test Examples 13 and 22, the amount of the polycarboxylic acid type polymer compound used in the synthesis of the resin particles contained in the resin emulsion was too small, and therefore the adsorption protection layer was sufficiently formed on the surface of the particles. It is thought that it was not formed effectively. As a result, it is considered that D _A /D _B became 1 or more, and the aggregation rate was higher than that of the resin emulsions obtained in Test Examples 1 to 11 and Test Examples 16 to 20.

In Test Example 14, it is considered that the adsorption protective layer was not sufficiently effectively formed on the resin particles because the polycarboxylic acid type polymer compound was used in the mode of being added to the produced resin emulsion, whereby D _A /D _It is considered that when _B was 1 or more, the aggregation rate was high.

Further, in Test Examples 1 to 11 and Test Examples 16 to 20, like those, in comparison with Test Examples 12 to 14 and Test Examples 21 to 22 using a (meth)acrylic acid and/or polycarboxylic acid type polymer compound. However, a resin emulsion having better mechanical stability was obtained. The cause of this difference was examined from a viewpoint different from the amount of the (meth)acrylic acid or polycarboxylic acid type polymer compound used. As a result, in addition to the value of D _A /D _B , the difference with the reference of the zeta potential It was confirmed that there was. That is, in the resin emulsions of Test Examples 1 to 11 and Test Examples 16 to 20, the difference from the reference of the zeta potential was 10 mV or more in absolute value (specifically, the absolute value of the zeta potential was more than the reference absolute value. In contrast, the resin emulsions of Test Examples 12 to 14 and Test Examples 21 to 22 had an absolute value difference of less than 10 mV from the standard zeta potential. Therefore, the resin particles having an adsorption protection layer of a polycarboxylic acid type polymer compound on the particle surface and the resin particles corresponding to at least one of the resin particles containing a structural unit derived from (meth)acrylic acid are contained, and D _A / D _B is less than 1, and resin emulsion difference between the reference zeta potential is the absolute value 10mV or more, the mechanical stability was confirmed to be better.

Claims (5)

_A first measurement step of measuring an average particle diameter D _A of the resin emulsion by a laser diffraction/scattering method,
A second measurement step of measuring the average particle diameter D _B of the resin emulsion by a dynamic light scattering method,
From the measured average particle diameter D _A and the measured average particle diameter D _B , a calculation step of calculating D _A /D _B , which is the ratio thereof,
_A method for evaluating mechanical stability of a resin emulsion, comprising: an evaluation step of evaluating the quality of mechanical stability of the resin emulsion based on the value of D _A /D _B. The mechanical stability evaluation of the resin emulsion according to claim 1, wherein in the evaluation step, when the value of D _A /D _B is less than 1, it is determined that the mechanical stability of the resin emulsion is good. Method. The method for evaluating the mechanical stability of a resin emulsion according to claim 1, wherein the resin emulsion is a resin emulsion containing (meth)acrylic resin particles. The resin emulsion is a resin emulsion corresponding to at least one of a resin emulsion containing a polycarboxylic acid type polymer compound; and a resin emulsion containing particles containing a structural unit derived from (meth)acrylic acid. 4. The method for evaluating mechanical stability of the resin emulsion according to any one of 3 to 3. Resin particles (I) containing particles obtained by polymerizing a monomer component and an adsorption protective layer having a polycarboxylic acid type polymer compound adsorbed on the surface of the particles, and a monomer component containing (meth)acrylic acid Containing resin particles corresponding to at least one of the polymerized resin particles (II),
The ratio D _A /D _B of the average particle size D _A by the laser diffraction/scattering method and the average particle size D _B by the dynamic light scattering method is less than 1,
The zeta potential is 10 mV or more in absolute value of the difference from the zeta potential measured under the same conditions for the same reference emulsion except that the polycarboxylic acid type polymer compound and the (meth)acrylic acid are not contained. Resin emulsion.

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