JP6683600B2 - Pigment dispersion resin composition - Google Patents

Description

The present invention relates to a pigment-dispersed resin composition. More specifically, it relates to a pigment-dispersed resin composition that is suitable for the field of industrial coatings in the production of industrial products such as automobile coatings and is used as a primary color for aqueous coatings.

The pigment-dispersed resin composition is used as a primary color for coatings for coloring and toning various coatings, and is generally called primary color (pigment) paste or the like. Particularly, in the industrial coating field, for example, in a coating system for forming a laminated coating film by electrodeposition, intermediate coating, topcoat base, clear, etc. in automobile coating process, the topcoat base coating material is colored with the pigment-dispersed resin composition. Is being done. Since it affects the performance and quality of automobile top coating base paints and the like, it is required to develop an excellent pigment-dispersed resin composition suitable for such a coating system and the like.
By the way, in recent years, as measures against volatile organic compounds (VOC) are required from factories and the like, demand for water-based paints as one of environment-friendly paints is increasing in the industrial paints field. Therefore, as a pigment-dispersed resin composition, one that can be applied as a primary color for an aqueous paint is widely used.

Regarding a conventional pigment-dispersed resin composition, a bisacetoacetarylide pigment (a), a styrene-acrylic acid copolymer (b), a basic compound (c), a wetting agent (d) and a kneading aid (e). Which is a solid pigment composition at room temperature containing styrene, the styrene-acrylic acid copolymer (b) has an acid value of 145 to 175, the kneading aid (e) contains a surfactant, and Those having an HLB of ~ 12 are disclosed (for example, refer to Patent Document 1 and the like).
Further, a composition containing an acetylene series diol ethylene oxide / propylene oxide adduct that acts as a surfactant, such as a pigment or a pigment dispersant, is disclosed (see, for example, Patent Document 2).
Further, a water-based coating composition containing a glycidyl ether-capped acetylene diol ethoxylate such as a pigment and a pigment dispersant has been disclosed (see, for example, Patent Document 3).

International Publication No. 2011/034043 JP, 2004-339226, A JP, 2003-238472, A

However, in the above-mentioned prior art, in addition to the dispersion characteristics of the pigment itself, there is no disclosure about suppressing the increase in viscosity with time and improving storage stability.
That is, in the pigment dispersion in the paint field and the like, usually, a dispersant is used, in the pigment dispersion step using it, wetting of the dispersant to the pigment, mechanical disintegration and reaggregation of the pigment by a disperser, It can be divided into stages such as stabilization of the pigment in the resin composition. Among these, the wettability related to the dispersion characteristics of the pigment and the stabilization related to the storage stability are important factors that determine the superiority or inferiority of the pigment dispersibility. Characteristic is recognized as an issue and the factor is not taken into consideration.

By the way, when the coating composition is applied to industrial applications, bake curing is generally performed in the coating / curing process. For example, in automobile coating, the coating / curing process of bodies mass-produced in the production line. In order to reduce energy costs, that is, to reduce so-called CO ₂ , high non-volatile differentiation is required, and coating materials that can be industrially cured at a relatively low temperature are required. When a conventional pigment-dispersed resin composition is used for curing at such a low temperature, the degree of freedom in blending design in top coatings, etc. is reduced, and the coating performance such as appearance using hue or saturation as an index decreases. Will be done. Since this is due to the influence of the dispersant, it is required to reduce the dispersant in the pigment-dispersed resin composition, that is, the resin content to achieve a high pigment content (high PWC). It was
Under such circumstances, if the PWC is increased in the pigment-dispersed resin composition, it becomes difficult to disperse the pigment and the dispersibility decreases, so that the dispersed particle size becomes large, or the dispersion time becomes long and the productivity decreases. In addition, there is a problem that storage stability is lowered.

The present invention has been made in view of the above circumstances, and exhibits good pigment dispersibility, and in particular, it has excellent dispersion characteristics in which the dispersed particle size and dispersion time are used as indicators even when the pigment content (high PWC) is increased. In addition, by providing a pigment-dispersed resin composition that can secure good storage stability and can also have good coating performance such as appearance, in the field of industrial coating such as automobile coating, top coating base coating, etc. The purpose is to contribute to the improvement of coating film performance such as the degree of freedom of formulation design and appearance.

In the present invention, in a resin that functions as a dispersant, that is, in a pigment-dispersed resin composition in which a pigment is dispersed by a dispersing resin, it is first necessary to use a dispersing resin made of a polymer having a hydrophilic chain for an aqueous coating. Focusing on its usefulness in primary colors, and then examining the wettability related to the dispersion characteristics of the pigment and the stabilization related to storage stability, it was found that the use of an additive having a relatively low surface tension to improve the wettability. Effectiveness and stabilization are influenced by the molecular weight of the hydrophilic chain of the dispersing resin, and a dispersing resin having a relatively large molecular weight hydrophilic chain, especially for dispersing where the hydrophilic chain constitutes the side chain of the polymer We have found that the resin is effective. Then, one kind of additive or not only one kind of dispersing resin is used to disperse the pigment, but an additive (wetting agent) that contributes to improving the wettability and a dispersing resin (stabilizer) that contributes to improving the stability. It has been found that by performing the pigment dispersion in combination with, it is possible to achieve a high PWC while maintaining good dispersion characteristics. The wetting agent quickly adsorbs on the pigment surface (including pores), interacts with the active surface appearing on the pigment surface by crushing the pigment, and has the effect of temporarily preventing reaggregation. It is considered to have the effect of covering the dispersed pigment particles and ensuring stability. Regarding the molecular weight of the hydrophilic chain of the dispersing resin that constitutes the stabilizer, when the size of the molecular weight of the hydrophilic chain is specified by specifying its lower limit, the dispersion time is shortened in the pigment dispersion step, and the particle size achieved by dispersion is reduced. It has been found that the storage stability can be secured while reducing the size. As a result, it is possible to exert a remarkable effect that the dispersion characteristics can be made excellent even if the PWC is increased, and it is thought that the above problems can be solved satisfactorily, and the present invention has been achieved. .

That is, the present invention is a pigment-dispersed resin composition containing a pigment and a dispersing resin, the dispersing resin is essentially a polymer having a hydrophilic chain, the number average molecular weight per hydrophilic chain is It is 1000 or more, and the pigment-dispersed resin composition is a pigment-dispersed resin composition which further contains a surfactant.

Regarding the pigment, the dispersing resin and the surfactant which are the constituent elements of the pigment-dispersed resin composition of the present invention, the dispersing resin and the surfactant will be described in detail first, and then the composition and the preparation method of the pigment and the pigment-dispersed resin composition. , The application will be described.
The preferred embodiments of the present invention are shown together with the description of the matters specifying the invention of the present invention, but a combination of two or more individual preferred embodiments of the present invention is also a preferred embodiment of the present invention.
In addition, when there are some preferable numerical ranges for the items shown in the numerical ranges, the lower limit value and the upper limit value thereof can be selectively combined to obtain a preferable form.

[Dispersion resin]
The dispersion resin essentially requires a polymer having a hydrophilic chain, and the number average molecular weight per hydrophilic chain (also referred to as hydrophilic chain molecular weight) is 1,000 or more. That is, it is a polymer having a hydrophilic portion and a hydrophobic portion, and has a hydrophilic chain in which hydrophilic structural units (eg, oxyethylene groups) that are hydrophilic portions are linked, and each hydrophilic chain Is a resin used as a so-called pigment dispersant, which is composed of a polymer having a number average molecular weight of at least the above specific value. Regarding the distinction between the hydrophilic part and the hydrophobic part, the part consisting of a monomer unit having a relatively hydrophilic group (preferably an oxyalkylene group) is regarded as the hydrophilic part, and the other part is Is defined as a hydrophobic site.
Examples of the polymer having a hydrophilic chain include those having a hydrophilic chain in the main chain if it is a polymer composed only of the main chain, and the main chain if it is a polymer composed of a main chain and side chains. And / or those having a hydrophilic chain in the side chain. When the main chain has a hydrophilic chain, one or more block sites of the block polymer forming the main chain are hydrophilic chains. When the side chain has a hydrophilic chain, in one side chain, the entire side chain is a hydrophilic chain, or the side chain is composed of a block polymer, one or a plurality of block sites of the block polymer It becomes a hydrophilic chain. The entire side chain is a hydrophilic chain means that all the monomer units constituting the side chain have a hydrophilic group, for example, when the polyalkylene glycol chain described later is a side chain, with the main chain It will be composed of a monomer unit having an oxyalkylene group having a residue at the bonding site, a monomer unit having an oxyalkylene group, and a monomer unit having an oxyalkylene group having a terminal group. The entire side chain becomes a hydrophilic chain.

Among these, the polymer having a hydrophilic chain preferably has a side chain and the side chain is a hydrophilic chain. That is, it has one or more side chains with respect to the main chain, and when it has one side chain, the one side chain is a hydrophilic chain, and when it has a plurality of side chains, it has a plurality of side chains. It is preferable that the side chains in some or all of the chains are hydrophilic chains. More preferably, all of the side chains are hydrophilic chains, and the number average molecular weight per side chain which is the hydrophilic chain is not less than the specified value. A resin made of a polymer having a side chain is also referred to as a comb dispersant, and the polymer is also referred to as a comb polymer (graft polymer).
It is preferable that the dispersion resin is composed mainly of the comb polymer, that is, contains 55% by mass or more of the comb polymer in terms of solid content, and may contain other polymer or the like. However, more preferably, all the polymers contained in the dispersing resin are substantially the above comb-shaped polymer.

If the number average molecular weight per hydrophilic chain of the polymer is less than 1000, it becomes impossible to secure sufficient stability for the dispersed pigment particles. The lower limit of the number average molecular weight per hydrophilic chain is preferably 1200 or more, more preferably 1400 or more, still more preferably 2000 or more.
Thus, in the polymer having the above-mentioned hydrophilic chains, those having a number average molecular weight of 1200 or more per one hydrophilic chain and those having a number average molecular weight of 1400 or more per one hydrophilic chain are It is a preferred embodiment of the invention.
The upper limit of the number average molecular weight per hydrophilic chain is preferably 10,000 or less, more preferably 5,000 or less, because the viscosity increase affects the preparation of the dispersing resin and the pigment dispersion.
The number average molecular weight per hydrophilic chain can be calculated from the number average molecular weight of the raw material forming the polymer.

In the comb polymer, the average number of side chains per molecule of the polymer is preferably 1 to 12. If the average number of side chains exceeds 12, the molecular weight of the comb polymer becomes too large, which affects the preparation of the resin for dispersion and the pigment dispersion. The more preferable range of the average number of side chains is 1 to 5, and the more preferable range is 2 to 4. It is preferable that all of these side chains are hydrophilic chains and that the molecular weight of the side chains satisfies the above-mentioned definition of the number average molecular weight per hydrophilic chain.
The position of the side chain in the main chain of the comb polymer is not particularly limited.

The hydrophilic chain is preferably a polyalkylene glycol chain (polyoxyalkylene chain). Therefore, the comb polymer is preferably a comb polymer having a polyalkylene glycol chain as a side chain. More preferably, substantially all the hydrophilic chains are polyalkylene glycol chains, and in the case of the comb polymer, substantially all the side chains are polyalkylene glycol chains.
In a preferred form of the polymer having a hydrophilic chain according to the invention, the site of the polyalkylene glycol chain is a relatively hydrophilic site, and the other site is a hydrophobic site containing no polyalkylene glycol chain. In a preferred form of the comb polymer, the main chain is relatively hydrophobic and the side chains are hydrophilic, that is, hydrophilic chains. In such a case, when it is used as a primary color for an aqueous paint, the hydrophobic site acts to cover the pigment particles, and the hydrophilic site has an affinity for the aqueous medium to effectively exhibit the steric hindrance effect of the hydrophilic chain, resulting in dispersion. The stability becomes more excellent. In the case of a comb polymer in which the side chain is a hydrophilic chain, this steric hindrance effect is more effectively exhibited.

As the polyalkylene glycol chain, one formed by an oxyalkylene group having 2 to 4 carbon atoms is preferable. More preferably, it is composed of an oxyethylene group and / or an oxypropylene group. These may be any addition forms such as random addition, block addition, and alternate addition. When the side chain has an oxyethylene group and / or an oxypropylene group, the average number of moles of the oxyethylene group in the side chain: the average number of moles of the oxypropylene group, from the viewpoint of dispersion stability when used as a primary color for aqueous paints. A preferable range of the ratio is 100 to 50: 0 to 50, a more preferable range is 90 to 55:10 to 45, and a further preferable range is 85 to 60:15 to 40.

When the polyalkylene glycol chain is used as a side chain, the end portion of the polyalkylene glycol chain on the side not bonded to the main chain is preferably a hydrocarbon group having 4 or less carbon atoms. If the number of carbon atoms exceeds 4, the dispersibility in an aqueous medium may decrease when the pigment-dispersed resin composition is used as a primary color for an aqueous paint. The above-mentioned terminal portion is more preferably an alkyl group having 3 or less carbon atoms, further preferably a methyl group, an ethyl group, a propyl group, and most preferably a methyl group.

The hydrophilic chain may also be a polymer or copolymer that essentially includes a monomer unit having an ionic functional group. Examples of the ionic functional group include an acid group such as a carboxyl group, a sulfo group, a phosphoric acid group and an aminocarboxylic acid group, and a group in which these are neutralized. Among them, a carboxyl group is preferable, and a hydrophilic chain can be formed in the main chain and / or the side chain by adjusting the amount of the ionic functional group in the main chain and / or the side chain.
The polymer having a hydrophilic chain may have a form having both a polyalkylene glycol chain as a hydrophilic chain and a polymer or copolymer that essentially includes a monomer unit having an ionic functional group. .

The dispersion resin preferably has an acid value of 50 mgKOH / g or less. That is, it is preferable that the comb-shaped polymer (polymer having the above-mentioned hydrophilic chain) constituting the dispersing resin has an acid value in terms of solid content of not more than the specified value. This makes it possible to improve the pigment dispersibility of the dispersing resin and to make the coating film formed from the coating material using the pigment-dispersing resin composition exhibit good basic performance. The upper limit of the acid value is more preferably 40 mgKOH / g or less. The lower limit of the acid value is not particularly limited, but 2 mgKOH / g or more is preferable.
The acid value is preferably provided by the acid group of the monomer unit in the hydrophobic site of the polymer. In the case of a comb-shaped polymer, it is preferable that the main chain serves as a hydrophobic site and is provided by the acid group contained in the monomer unit in the main chain. Thereby, the steric hindrance effect of the hydrophilic chain (preferably the side chain which is a hydrophilic chain) that stabilizes the hydrophobic site, preferably the main chain, is adsorbed on the surface of the pigment particle and the pigments are not aggregated is sufficiently exhibited. Will be.

Examples of constituents of the hydrophobic portion of the polymer include, for example, styrene-acid-based monomer copolymers, phenol novolac epoxy resins, (meth) acrylamine-based polymers or copolymers, and side chains. Examples thereof include a (meth) acrylic polymer or copolymer having a glycidyl group. In the comb polymer, it is preferable that the main chain is composed of these polymers or copolymers.
Among them, the hydrophobic portion is easy to exert the effect of covering the dispersed pigment particles to ensure stability, and also from the advantage of being easy to industrially manufacture, the copolymer of styrene-acid-based monomer is Preferably, for example, a styrene-maleic anhydride copolymer containing styrene and maleic anhydride as an essential monomer component, and a styrene-maleic anhydride- (meth) acrylic monomer copolymer are suitable. Most preferably, it is a styrene-maleic anhydride copolymer. The styrene-maleic anhydride copolymer and the styrene-maleic anhydride- (meth) acrylic monomer copolymer are also referred to as a styrene-maleic anhydride copolymer. In addition, these polymers and copolymers may contain other monomer units as needed.

In the styrene-maleic anhydride copolymer, it is preferable that the monomer units of styrene and maleic anhydride are the main constituents (substantially all). Further, the molar ratio of styrene and maleic anhydride is not particularly limited, and may be appropriately adjusted so as to satisfy the preferable range of the acid value. For example, the ratio of the number of moles of styrene to the number of moles of maleic anhydride is preferably 90 to 10:10 to 90. With respect to the above molar ratio, a more preferable ratio is 70 to 30:30 to 70, and a further preferable ratio is 60 to 40:40 to 60.

As for the molecular weight of the hydrophobic moiety of the polymer having a hydrophilic chain, the number average molecular weight is preferably 1,000 or more and 20,000 or less. When the number average molecular weight of the hydrophobic site is less than 1000, it becomes difficult to exhibit the action of adsorbing to the pigment particles in which the hydrophobic site is dispersed and ensuring stability, and the number average molecular weight of the hydrophobic site is 20000. If it exceeds, the viscosity increase may affect the preparation of the dispersing resin and the pigment dispersion. The lower limit of the number average molecular weight of the hydrophobic moiety is more preferably 1,500 or more. The upper limit of the number average molecular weight of the hydrophobic moiety is preferably 10,000 or less, more preferably 5000 or less, and particularly preferably 3000 or less. In the comb polymer, the molecular weight of the main chain is preferably within the above range.
The ratio of the hydrophobic site and the hydrophilic site (hydrophilic chain) in the polymer having the hydrophilic chain is set so that the hydrophobic site and the hydrophilic site can effectively exhibit their respective functions. It is preferable that the ratio of the mass: of the hydrophilic part is 80 to 20:20 to 80. More preferably, the ratio is 70 to 30:30 to 70. In the comb polymer, the ratio of the main chain that is a hydrophobic site to the side chain that is a hydrophilic site (hydrophilic chain) may be within the above range.

The preparation of the polymer having a hydrophilic chain can be carried out by a commonly used graft modification in the case of a comb-shaped polymer which is a preferable form. For example, as a preferable form, a comb-shaped polymer having a side chain as a polyalkylene glycol chain is used. When the polymer is prepared, the polymer or copolymer constituting the main chain may be reacted with a compound having a polyalkylene glycol chain for grafting. As the compound having a polyalkylene glycol chain, polyalkylene glycol monoalkyl ether (polyalkylene oxide monoalkyl ether) can be used as a compound having an alkyl group at one end of the compound obtained by addition-polymerizing alkylene oxide. Further, as a compound having an alkyl group at one end and an amino group at the other end of a compound obtained by addition-polymerizing an alkylene oxide, a polyalkylene glycol monoalkyl ether monoamine (polyalkylene oxide monoalkyl ether Monoamine) can be used. For example, in the case of a polyalkylene glycol chain having an oxyethylene group and an oxypropylene group, a side chain can be formed using ethylene oxide / propylene oxide copolymer monomethyl ether or ethylene oxide / propylene oxide copolymer monomethyl ether monoamine.
In the case of a block polymer, it can be carried out by a commonly used block polymerization, for example, it may be prepared by reacting a monomer component with the end of a chain compound having a polyalkylene glycol moiety.

In the present invention, a comb polymer having a styrene-maleic anhydride copolymer as the main chain and a polyalkylene glycol chain as the side chain is one of the preferred embodiments, and in the case of preparing such a polymer. Is to be grafted by reacting a styrene-maleic anhydride copolymer with a compound having a polyalkylene glycol chain. The compound having a polyalkylene glycol chain is preferably a monoalkyl ether of polyalkylene glycol or a monoalkyl ether monoamine of polyalkylene glycol, more preferably an ethylene oxide / propylene oxide copolymer monomethyl ether or ethylene oxide / propylene oxide copolymer. An example is a combined monomethyl ether monoamine.
When the maleic anhydride monomer unit has an excessive carboxyl group, it can be reacted by capping the carboxyl group with butyl cellosolve or the like.
A preferred embodiment of the comb-shaped polymer prepared by using a styrene-maleic anhydride copolymer and an ethylene oxide / propylene oxide copolymer monomethyl ether or an ethylene oxide / propylene oxide copolymer monomethyl ether monoamine is as follows. A form having the monomer units (1), (2) and (3), a form having the following monomer units (1) and (3), and a form having the following monomer units (2) and (3) Can be mentioned. In this embodiment, these monomer units may be in the form of random, block or alternating addition.
In such a comb-shaped polymer, the hydrophobicity can be enhanced by the monomer unit of styrene, and thus the affinity with the highly hydrophobic pigment can be enhanced.

In the chemical formulas representing the monomer units (1), (2) and (3), R ¹ is preferably the same or different and represents an alkylene group having 2 to 4 carbon atoms. R ¹ is more preferably an ethylene group or a propylene group. _{^{- (R 1 O) n1 -}} , - oxyalkylene groups represented by, if composed of oxyethylene group and oxypropylene _{group, - - (R 1 O)} n2 (CH 2 CH 2 O) n3 - When _- a and random, block or alternating addition to form _{- (CH 2 CHCH 3 O)} n4.
R ² is preferably the same or different and represents a hydrocarbon group having 4 or less carbon atoms. R ² is more preferably an alkyl group having 3 or less carbon atoms, further preferably a methyl group, an ethyl group or a propyl group, and most preferably a methyl group.
X ¹ is the same or different and represents NH or O. X ² are the same or different and represent N or O. When X is O, the monomer unit does not have a group represented by — (R ¹ O) n ₂ —R ² .
In one molecule of comb polymer, m1, m2, m3, n1, n2, n3, and n4 represent integers of 0 or more, and are appropriately set in consideration of the molecular weight ranges of the main chain and side chains that are hydrophilic chains. It is preferable.

Regarding the calculation of the number average molecular weight per side chain which is the above-mentioned hydrophilic chain, the molecular weight of one side chain is one side chain except for the groups belonging to the monomer units (repeating units) constituting the main chain. It is the total molecular weight of the constituent monomer units and the groups at the side chain ends. Examples of the group at the end of the side chain include a group at one end site not bound to the main chain and a residue at one end site after bound to the main chain.
Therefore, in the above-mentioned monomer units (1) and (2), the total molecular weight of the oxyalkylene group, which is a monomer unit constituting the polyalkylene glycol chain, and the groups at both terminal sites (the groups at one terminal site). -R ² and the total molecular weight of -NH-, -N- or -O-) which is the residue at the other one end site is the molecular weight constituting one side chain, and the side chain is based on this. The number average molecular weight per (hydrophilic chain) will be calculated or measured.

In the preparation of the comb polymer, when a monoalkyl ether monoamine of polyalkylene glycol is added to the maleic anhydride monomer unit as a compound having a polyalkylene glycol chain and grafted, a secondary amide bond is formed at the bonding site. And / or imide bonds will result. In this case, the generation ratio of the secondary amide bond and the imide bond is not particularly limited, and when the dispersion property of the pigment is affected by this ratio and the surface property of the pigment, it may be adjusted appropriately according to the surface property of the pigment. Good.
In the monomer units (1) and (2), when X ¹ is NH, it is a secondary amide bond, and when X ² is N, it is an imide bond.

The comb polymer preferably contains an acid-based monomer unit in the main chain as described above, but in this case, it may be neutralized and used depending on the pigment surface. In that case, a general basic compound can be used as the neutralizing agent, and examples thereof include amine compounds, ammonia, hydroxides and carbonates of alkali metals or alkaline earth metals, and one or more of them. Two or more kinds can be used.

[Surfactant]
As the above-mentioned surfactant, those having an action of lowering the surface tension (dynamic surface tension) of the pigment with respect to the aqueous medium are suitable. As a result, the wettability of the pigment with respect to the aqueous medium can be improved, and in the pigment dispersion step, the pigment surface can be quickly adsorbed and coated to prevent reaggregation of the crushed pigment. Regarding the measurement of the effect of lowering the surface tension, for example, a certain amount of pigment is added to an aqueous medium solution in which a dispersing resin and a surfactant are added to an aqueous medium such as water, and it floats on the aqueous medium. It can be carried out by measuring the time required for the powdery pigment to disperse in the aqueous medium solution and disappear. A good correlation that the lower the dynamic surface tension of the aqueous medium solution containing the dispersing resin and the surfactant, the shorter the time required for the wetting was observed, and the case where only the dispersing resin was added was observed. In comparison, when the dispersing resin and the surfactant that lowers the dynamic surface tension are added, the above measurement time (time required for wetting) becomes shorter. When used in combination with, the wettability of the pigment with respect to the aqueous medium can be improved. In addition, the lower the dynamic surface tension, the smaller the particle size of the pigment reached in the pigment dispersion step, and thus the effect of shortening the dispersion time and achieving high PWC can be sufficiently exhibited.
The surfactant preferably has a dynamic surface tension of 10 to 50 mN / m when added to an aqueous medium together with a dispersing resin. A more preferable range of dynamic surface tension is 25 to 45 mN / m. The dynamic surface tension can be measured using an automatic dynamic surface tension meter BP-5 (manufactured by Kyowa Interface Science Co., Ltd.).

The surfactant preferably has an HLB value of 2-18. The HLB value is generally used as a value representing the degree of affinity of a surfactant for water and oil, and can be calculated by, for example, the Griffin's formula. In this case, it is defined by 20 × (molecular weight of hydrophilic portion in the surfactant) / (molecular weight of the entire molecule of the surfactant). When it has a polyalkylene glycol chain (polyoxyalkylene group) described below, the site becomes a hydrophilic site and the other site becomes a hydrophobic site.
When the HLB value is less than 2, the hydrophilicity is excessively lowered and the pigment dispersibility when used as a primary color for an aqueous paint is lowered, and when the HLB value is more than 18, the hydrophilicity is too strong. There is a possibility that the adsorption effect on the surface of the pigment may be reduced. The lower limit of the HLB value is preferably 8 or more, more preferably 10 or more, and the upper limit of the HLB value is preferably 16 or less, more preferably 15 or less.
As the above-mentioned surfactant, as used in Examples described later, "Enviro Gem 2010", "Surfinol CT-111", "Surfinol CT-121", "Surfinol CT-" manufactured by Air Products Japan, Inc. 131 "," Surfinol CT-211, "" Surfinol CT-221 "," Surfinol CT-231 "," Surfinol 420 "," Surfinol 440 "," Surfinol 465 ";" ADEKANOL L-61 "manufactured by Adeka. "ADEKANOL L-64";"NeugenXL-40","NeugenXL-60","NeugenXL-80","NeugenXL-400D" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd .; "Newcol N704" manufactured by Nippon Emulsifier Co., Ltd. , "N wcol N710 "," Newcol N714 ", it is possible to use a commercially available product such as" Newcol N740 ".

Further, the surfactant preferably has a number average molecular weight of 150 to 5,000. If the number average molecular weight is out of this range, the effect of adsorbing the surfactant on the pigment surface may not be effectively exhibited. 300-3500 are more preferable and, as for the number average molecular weight of the said surfactant, 400-2500 are still more preferable.
In the present invention, as the surfactant, a single compound may be used or a plurality of compounds may be mixed and used. When a plurality of compounds are used in combination, the HLB value is a weighted average of the HLB values of the compounds contained in the surfactant, and the number average molecular weight is the number average molecular weight of the compounds contained in the surfactant. It is preferably within the range.

Furthermore, as a preferred form of the above-mentioned surfactant, a nonionic surfactant, in particular, a form in which an acetylene glycol ethylene oxide adduct is essential is preferable, along with it, acetylene glycol, polyoxyethylene alkyl ether, and, It may contain at least one selected from the group consisting of a phenol ethylene oxide adduct. As a preferred embodiment of the above-mentioned surfactant, a form containing acetylene glycol and / or acetylene glycol ethylene oxide adduct and polyoxyethylene alkyl ether and phenol ethylene oxide adduct, acetylene glycol and / or acetylene glycol ethylene. It is a form containing an oxide adduct and a polyoxyethylene alkyl ether or a phenol ethylene oxide adduct.

When acetylene glycol is used in the preferred form of the above-mentioned surfactant, it is preferable to use a polyoxyethylene alkyl ether and / or a phenol ethylene oxide adduct together with acetylene glycol. More preferably, a polyoxyethylene alkyl ether is used together with acetylene glycol.
By these, the effect of lowering the surface tension of the pigment with respect to the aqueous medium can be effectively exhibited.
In the above compound, part of the ethylene oxide moiety may be replaced with another alkylene oxide such as propylene oxide.

The compounds constituting the above surfactant are represented by the following preferable chemical formulas.
The acetylene glycol is preferably a compound represented by the following chemical formula (4).

In the formula, R ³ , R ⁴ , R ⁵ , and R ⁶ are the same or different and are linear or branched hydrocarbon groups having 1 to 10 carbon atoms, preferably linear chains having 1 to 8 carbon atoms or Represents a branched alkyl group.

The acetylene glycol ethylene oxide adduct is preferably a compound represented by the following chemical formula (5).

In the formula, R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ are the same or different and are linear or branched hydrocarbon groups having 1 to 10 carbon atoms, preferably linear chains having 1 to 8 carbon atoms or Represents a branched alkyl group. n5 and n6 are the same or different and each represent an integer of 0 to 20, not simultaneously 0, and preferably an integer of 1 to 20.

The polyoxyethylene alkyl ether is preferably a compound represented by the following chemical formula (6) or (7).

In the formula, x and y represent an integer of 9 to 14 where x + y may be 0. n7 represents an integer of 2 to 20.

In the formula, z represents an integer of 9 to 14. n7 is the same as above.

The phenol alkylene oxide adduct is preferably a compound represented by the following chemical formula (8).

In the formula, R ¹¹ represents a linear or branched alkyl group having 7 to 11 carbon atoms. n8 represents an integer of 1 to 30.

In the chemical formula (5) in the acetylene glycol ethylene oxide adduct, the number of carbon atoms forming the main chain of the alkyl group represented by R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ is preferably 1 to 8, and more preferably It is preferably 1 to 6, and more preferably 1 to 4. Also, R ⁷ and R ⁸ are methyl groups, and R ⁹ and R ¹⁰ are the same or different and are selected from the group consisting of methyl group, ethyl group, propyl group, butyl group and isobutyl group. Is preferred. More preferably, R ⁷ and R ⁸ are methyl groups and R ⁹ and R ¹⁰ are isobutyl groups. As for n5 and n6, the value of n5 + n6 is preferably 30 or less.

A more preferable form of the acetylene glycol ethylene oxide adduct is a compound represented by the following chemical formula (9).

In the formula, n5 and n6 are the same as above.

The above-mentioned surfactants can be classified into single type compounds, gemini type compounds and the like in their chemical structures, and among them, it is preferable to include gemini type compounds. The single type compound is a compound having one or more hydrophilic moieties and one hydrophobic moiety in one molecule in the surfactant, and preferably one hydrophilic moiety in one molecule. It is a compound having one hydrophobic site. For example, a more preferable form of the polyoxyethylene alkyl ether having a linear structure in which a linear alkyl group that is a hydrophobic site is bonded to a polyoxyethylene group that is a hydrophilic site is represented by the chemical formula (7). The compounds will be classified as single-type compounds.

On the other hand, the Gemini type is a compound having a structure in which a plurality of molecules capable of forming a surfactant are bound via a binding site, and preferably two molecules capable of constituting a surfactant are acetylene. It is a compound having a structure bonded through a group. More preferably, the hydrophilic portion is a polyoxyalkylene group (preferably a polyoxyethylene group) and is a Gemini type compound having a structure in which it is bonded via an acetylene group, and this is also referred to as an acetylene glycol type compound. For example, the above-mentioned acetylene glycol ethylene oxide addition, which is a form in which two sites in which a branched chain alkyl group that is a hydrophobic site is bonded to a polyoxyethylene group that is a hydrophilic site are bonded via an acetylene group that is a bonding site. The compound represented by the chemical formula (9) in a more preferable form of the product is classified into a gemini type compound (acetylene glycol type compound).

Due to its chemical structure, the Gemini-type compound has a hydrophobic site that easily interacts with and is adsorbed on the pigment surface as compared with a single-type compound, and the hydrophobic site that is an adsorption site on the pigment surface is of a single type. It is considered that it is bulkier than the adsorption site for compounds and the like, and the effective adsorption area of the surfactant molecule on the pigment surface becomes large, and therefore, the amount necessary for wetting the pigment surface can be small. Have the advantage of.
A preferred embodiment of the surfactant in the present invention is a form using the Gemini compound, more preferably a form using the Gemini compound as the acetylene glycol ethylene oxide adduct.
Preferred embodiments of the above-mentioned surfactants are also those in which the above-mentioned preferred compounds are predominantly prepared, more preferably substantially all active ingredients are constituted by the above-mentioned preferred compounds. It was done.

[Pigment]
The above-mentioned pigment is not particularly limited as long as it is used for coloring the coating material in which the pigment-dispersed resin composition of the present invention is used. For example, the specific surface area is preferably 15 m ² / g or more. Such a pigment is difficult to achieve a high PWC with a conventional dispersing resin, and when the present invention is applied to this, the ultimate particle size of the pigment is reduced in the pigment dispersion step, and storage stability is improved. The action and effect of the present invention, which is to improve the above, will be remarkably exhibited. The lower limit of the specific surface area is preferably 20 m ² / g or more, more preferably 50 m ² / g or more, and the upper limit of the specific surface area is more preferably 600 m ² / g or less.
The specific surface area of the pigment is defined as the total surface area per gram of pigment (m ² / g) and is reported by the pigment manufacturer. Further, the adsorption amount of nitrogen gas can be measured and calculated by the BET method. The measurement conditions in the BET method may be those usually used when measuring the specific surface area of the coating pigment.

Examples of the type of pigment include various organic and inorganic color pigments and extender pigments. The organic color pigments include azo lake pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indico pigments, perinone pigments, perylene pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, Examples of inorganic color pigments such as metal complex pigments include carbon black, yellow lead, yellow iron oxide, red iron oxide, titanium dioxide and the like, and examples of extender pigments include calcium carbonate, barium sulfate, clay, talc and the like. In addition, a bright pigment or the like may be used. These may be used alone or in combination of two or more.
Among them, the present invention can be preferably applied to carbon black and phthalocyanine-based pigments (particularly phthalocyanine blue), for which it has been difficult to achieve a high PWC with conventional dispersing resins.

[Pigment-dispersed resin composition]
Regarding the compounding composition of the pigment-dispersed resin composition, the PWC is set to be smaller as the specific surface area of the pigment is larger. However, in the present invention, the PWC is set to be higher than the conventional one regardless of the specific surface area. can do. When a pigment having a specific surface area of 300 m ² / g or more (for example, carbon black) is used, the PWC can be preferably 30 to 80%, more preferably 35 to 65%, and the specific surface area is 50 m. ^When using a pigment of ² / g or more and less than 300 m ² / g (for example, phthalocyanine blue), the PWC can be preferably 40 to 90%, more preferably 50 to 85%.

As the above-mentioned composition, it is preferable that the dispersion resin is 5 to 100 mass% and the surfactant is 0.5 to 75 mass% with respect to 100 mass% of the pigment. These are the values converted into solid content. If the proportion of the dispersing resin is out of the above range, the pigment dispersing action of the dispersing resin may not function sufficiently. If the proportion of the surfactant is less than 0.5% by mass, the effect of improving the wettability of the pigment may not be sufficiently exerted, and if it exceeds 75% by mass, the amount of the surfactant component is too much for dispersion. The action of the resin may be impaired.
The lower limit of the resin proportion for dispersion is more preferably 15% by mass or more, and the upper limit is more preferably 90% by mass or less, further preferably 85% by mass or less. Further, the lower limit of the surfactant ratio is more preferably 1% by mass or more, further preferably 3% by mass or more, and the upper limit is more preferably 35% by mass or less, further preferably 10% by mass or less.

In the above pigment-dispersed resin composition, when used as a primary color for an aqueous paint, it is preferable to use an aqueous medium such as water or a water-soluble solvent. A pigment-dispersed resin composition containing a pigment, a dispersing resin, a surfactant and an aqueous medium is one of the preferred embodiments of the present invention. In this case, the nonvolatile content of the pigment-dispersed resin composition is preferably 20 to 50% by mass when the total mass of the composition is 100% by mass, which is suitable for use as a paint primary color paste. If necessary, additives such as a defoaming agent, a surface conditioner, a preservative, a rust preventive and a plasticizer may be used.

The method for producing the pigment-dispersed resin composition of the present invention includes a step of dispersing the pigment with the dispersing resin and the surfactant. The disperser used in the dispersion step and the dispersion conditions may be appropriately set depending on the specific surface area, type, etc. of the pigment. Examples of the disperser include a sand grind mill (SG mill), a ball mill, a bead mill, a spike mill, a pearl mill, a dyno mill, a roll mill, an extruder, a paint shaker, and a kneader. Above all, it is preferable to use a media type dispersing machine such as a sand grind mill. Examples of media include zircon beads, zirconia beads, soda-lime glass beads, non-alkali beads, alumina beads, and silicon beads. The media particle size may be set within a usual range for pigment dispersion, and for example, the average particle size is preferably 0.03 to 5 mm, more preferably 0.05 to 2 mm. The average particle size of the media can be calculated by measuring the median size (D50 particle size) with a commercially available particle size distribution measuring device.
In the present invention, in the above dispersing step, a mode in which a media type disperser is used for dispersion, particularly a mode in which a sand grind mill is used for dispersion is preferable. As a result, even for a pigment having a large specific surface area, it becomes easy to achieve a high PWC while maintaining good pigment dispersion characteristics.

[Application]
The pigment-dispersed resin composition of the present invention can be used as a primary color paste for various colored paints, and is particularly preferably used as a primary color for aqueous paints. As the water-based paint, for example, those applied to the field of industrial paints used for automobile bodies, automobile parts, industrial machines, construction machines, and other industrial products are suitable.

As a preferred embodiment of the above pigment-dispersed resin composition, it is particularly preferable to use it as a primary color paste of an aqueous paint used as an automobile paint (preferably an automobile body paint). The above-mentioned pigment-dispersed resin composition is more preferably applied as a primary color paste for an intermediate coating composition and a top coating base coating in a coating system for automobiles for forming a laminated coating film, and more preferably a primary color paste for a top coating base coating. Applied as.

Examples of the water-based paint to which the pigment-dispersed resin composition is applied include, for example, an emulsion containing a resin component such as an acrylic resin, a polyester resin, and a fluorine-based resin and a melamine resin, a curing agent component such as a blocked isocyanate, and a dispersion. Used.
In the water-based paint to which the pigment-dispersed resin composition is applied, for example, the pigment-dispersed resin composition is 10 to 100 parts by mass, whereas the resin component of the water-based paint is 10 to 500 parts by mass, and the curing agent component is The amount may be 1 to 50 parts by mass, and the aqueous medium may be 10 to 500 parts by mass. By achieving a high PWC of the pigment-dispersed resin composition according to the present invention, it becomes possible to reduce the amount of the pigment-dispersed resin composition compounded in the aqueous paint.

When the pigment-dispersed resin composition of the present invention is used as a primary color for an aqueous paint, it becomes an environmentally friendly coating because it is an aqueous paint, and when the primary color for an aqueous paint is made to have a high PWC according to the present invention, a coating composition in an aqueous paint It is possible to increase the degree of freedom in design and suppress deterioration of coating film performance such as appearance deterioration due to raw material paste. Further, by improving the storage stability of the pigment-dispersed resin composition, it becomes possible to stably produce industrial products having good performance and quality.

The pigment-dispersed resin composition of the present invention has the above-mentioned constitution, and a pigment is obtained by using a surfactant (wetting agent) contributing to improving wettability and a dispersing resin (stabilizer) contributing to improving stability. Since it disperses, it exhibits good pigment dispersibility, and even when the pigment content is high (high PWC), it has excellent dispersion characteristics with the dispersed particle size and dispersion time as indicators, and also has good storage stability. It is possible to secure good properties and to obtain good coating performance such as appearance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, "part" means "part by mass" and "%" means "% by mass" unless otherwise specified.

<Measurement of ultimate particle size>
The pigment-dispersed resin composition obtained after the dispersion was diluted with a borate aqueous solution, and the median diameter (D50 particle diameter) was measured using a particle size distribution measuring device (Microtrack UPA 150-EX manufactured by Nikkiso Co., Ltd.).

<Measurement of viscosity>
The viscosity was measured using a viscometer (TV-22 type E type viscometer) manufactured by Toki Sangyo Co., Ltd. The measurement conditions were 50 rpm × 3 min, and 1 ° 34 ′ × R24, which was standard equipment, was used as the cone rotor.

<Examples 1 and 2 and Comparative Examples 1 and 2>
As shown in Table 1 below, various dispersing resins in which all of the side chains are hydrophilic chains, surfactants (Enviro Gem 2010, HLB values 13 to 14 manufactured by Air Products Japan, Inc.), deionized water and defoaming. The agent (BYK-011 manufactured by BYK Japan KK) was mixed at a predetermined ratio, and a blue pigment (Cyanine Blue G-314 manufactured by Sanyo Dye Co., specific surface area 64 m ² / g) was added thereto. The blending amount of the pigment was adjusted so that the blending amount of the active ingredient of the dispersing resin was 40% with respect to the blending amount of the pigment. The pigment-dispersed resin composition (primary color paste) according to Examples 1 and 2 and Comparative Examples 1 and 2 was obtained by dispersing using a paint shaker.
The particle size and viscosity of each of the obtained pigment-dispersed resin compositions were measured immediately after the completion of dispersion, and the viscosity was measured again after storage at 40 ° C. for 10 days. The results are shown in Table 1 below.

The following can be seen from the test results shown in Table 1 above.
When the number average molecular weight (side chain molecular weight) per side chain in the dispersing resin having a hydrophilic side chain is 1400 (Example 2, Comparative Example 2), immediately after dispersion (initial stage) and at 40 ° C. for 10 days. The viscosity was low even after storage. When the side chain molecular weight was 1000 (Example 1), the viscosity was low immediately after dispersion (initial), but the viscosity increased after storage at 40 ° C. for 10 days. On the other hand, in Comparative Example 1 in which the side chain molecular weight was 400, the initial viscosity was high, and the viscosity after storage at 40 ° C. for 10 days markedly increased, greatly exceeding 100 mPa · s. From the above results, it was found that by setting the side chain molecular weight to 1400, extremely good storage stability can be obtained. Further, when the side chain molecular weight was 1000, the storage stability was inferior to that in the case where the side chain molecular weight was 1400, but an effect of improving the storage stability was observed as compared with the case where the side chain molecular weight was 400.
Further, in Examples 1 and 2 in which the surfactant was used, the ultimate particle size could be reduced to about 150 nm, and in Comparative Example 2 in which the surfactant was not used, the ultimate particle size exceeded 200 nm. It was From this result, it is understood that the dispersion characteristics can be improved by using the surfactant.

<Examples 3 to 8>
As shown in Table 2 below, the pigment dispersion resins according to Examples 3 to 8 were performed in the same manner as in Example 2 except that the type of surfactant (HLB value) and the blending amount of each component were changed. A composition (primary color paste) was obtained.
For each of the obtained pigment-dispersed resin compositions, the ultimate particle size was measured immediately after the end of dispersion. The results are shown in Table 2 below.

From the test results shown in Table 2 above, the correlation between the HLB value of the surfactant and the ultimate particle size was found. That is, it was found that when the HLB value is 15 or less, the ultimate particle size tends to decrease as the HLB value increases, but when the HLB value exceeds 15, the ultimate particle size increases rapidly.

<Comparative example 3>
As shown in Table 3 below, a pigment-dispersed resin composition (primary color paste) according to Comparative Example 3 was obtained in the same manner as in Example 2 except that the type of dispersing resin was changed. The dispersing resin used in Comparative Example 3 did not contain a hydrophilic chain having a number average molecular weight of 1,000 or more.
For each of the pigment-dispersed resin compositions of Example 2 and Comparative Example 3, the ultimate particle size was measured immediately after the completion of dispersion, and the particle size was measured again after storage at 40 ° C. for 10 days. The results are shown in Table 3 below.

From the test results shown in Table 3 above, it was found that when a dispersing resin having a relatively large acid value was used, the ultimate particle size increased with time and storage stability decreased.

<Example 9 and Comparative Example 4>
As shown in Table 4 below, various dispersion resins, surfactants (manufactured by Air Products Japan, Enviro Gem 2010, HLB value 13 to 14), deionized water, and defoaming agents (manufactured by BYK Japan Japan, BYK). -011) was mixed at a predetermined ratio, and a red pigment (Daipiroxide ™ Red 8270, manufactured by Dainichiseika Kogyo KK, specific surface area 110 m ² / g) was added thereto. Dispersion was performed using a paint shaker to obtain a pigment-dispersed resin composition (primary color paste) according to Example 9 and Comparative Example 4.
For each of the obtained pigment-dispersed resin compositions, the ultimate particle size was measured immediately after the end of dispersion. The results are shown in Table 4 below.

The following can be seen from the test results shown in Table 4 above.
In Example 9 in which the surfactant was used, the ultimate particle size was smaller than in Comparative Example 4 in which the surfactant was not used. From this result, it was found that the dispersion characteristics can be improved by using the surfactant.

From the above Examples and Comparative Examples, while specifying the number average molecular weight per hydrophilic chain of the resin for dispersion used in the pigment dispersion resin composition, by using a surfactant, the dispersed particle size more than before The advantageous effect of the present invention that it is possible to improve the dispersion characteristics as an index, and that the storage stability is excellent, has also been demonstrated, and is achieved by the configuration of the present invention described in the present specification. It can be said that the technical significance of the present invention is fully supported by considering the action mechanism.

Claims (10)

A pigment dispersion resin composition containing a pigment and a resin for dispersion,
The dispersion resin essentially requires a polymer having a hydrophilic chain, and the number average molecular weight per hydrophilic chain is 1,000 or more,
The hydrophilic chain is at least one of a polyalkylene glycol chain, and a polymer or copolymer containing a monomer unit having an ionic functional group,
The pigment-dispersed resin composition further contains a surfactant,
The surfactant, HLB value of Ri 2-18 der, pigment dispersion resin composition characterized Rukoto which have a acetylene glycol ethylene oxide adduct. The pigment-dispersed resin composition according to claim 1, wherein the polymer having a hydrophilic chain has a side chain, and the side chain is a hydrophilic chain. The pigment-dispersed resin composition according to claim 1 or 2, wherein the polymer having a hydrophilic chain has a number average molecular weight of 1200 or more per hydrophilic chain. The pigment-dispersed resin composition according to any one of claims 1 to 3, wherein the polymer having a hydrophilic chain has an acid value of 50 mgKOH / g or less. The surfactant, pigment dispersion resin composition according to any number-average molecular weight of claims 1-4, characterized in that the 150-5000. The surfactant, pigment dispersion resin composition according to any one of claims 1 to 5, wherein the HLB value of 8 to 18. The pigment-dispersed resin composition according to claim 6 , wherein the surfactant has an HLB value of 10-18. The pigment-dispersed resin composition is characterized in that the dispersion resin is 5 to 100% by mass and the surfactant is 0.5 to 75% by mass based on 100% by mass of the pigment in terms of solid content. pigment dispersion resin composition according to any one of claims 1 to 7. The pigment, the pigment dispersion resin composition according to any one of claims 1 to 8, specific surface area, characterized in that it is 15 m 2 / ^g or more. The pigment dispersion resin composition, a pigment dispersion resin composition according to any one of claims 1 to 9, characterized in that is used as aqueous coating colors.