JPH03119088A - Thickener - Google Patents

Abstract

PURPOSE:To provide the subject thickener consisting of a copolymer composed of an ethylene-based unsaturated acid monomer and amino group-containing vinyl monomer as the main components, capable of adjusting to a wide range of viscosity in a wide range of pH and capable of keeping an aqueous suspension stable in a range of pH >= gel point. CONSTITUTION:An objective thickener consisting of a copolymer composed of (A) an ethylene-based unsaturated acid monomer such as (meth)acrylic acid, crotonic acid, fumaric acid, vinylsulfonic acid or mono(2-acryloyloxyethyl)acid phosphate and (B) an amino group-containing vinyl monomer such as methylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylamide, aminoethyl vinyl ether or 2-vinylpyridine as the main component monomers in a ratio of 0.1 <= the component (A)/the component (B)<1 (preferably 0.2 <=the component (A)/the component (B)<=0.7).

Description

[Detailed description of the invention] (b) Purpose of the invention [Industrial application field] The present invention is latex, emulsion, and water-based.

[Conventional technology]

Conventionally, polymers such as sodium polyacrylate, carboxymethyl cellulose, sodium alginate, xanthan gum, guar gum, alkali thickened latte, and couscous have been used as thickening and gelling agents for aqueous dispersions. However, these thickening and gelling agents thicken and gel the system when added, so it is not possible to freely control the point of action, such as thickening or gelling the system at a certain point during a certain process. However, as the temperature of the system increases, the viscosity decreases, making it less effective.

In addition, thickening and gelling agents that are generally referred to as heat-sensitive gelling agents, such as polyalkylene oxide, polyvinyl methyl ether, and polyalkylene oxide-modified organopolysiloxane, are also known; , substances with cloud points such as anionic surfactants and nonionic surfactants that coexist in the system, and electrolytes such as inorganic salts, which thicken and gel the system due to phase transition phenomena associated with temperature changes. etc., the gelation temperature may change significantly, or in some cases, the viscosity may not thicken or gel at all, and the types of aqueous dispersions that can be applied are limited.

[Problem to be solved by the invention]

The present inventors have developed a thickening and gelling agent that does not have the above-mentioned problems, that is, it does not thicken the aqueous dispersion when added, and when the pH is adjusted at any time, it is particularly low in alkali (p.
We need to find a thickening and gelling agent that can rapidly thicken and gel in the range of H7-11) and can be applied to any type of aqueous dispersion (we have conducted various studies). be.

(B) Structure of the Invention [Means for Solving the Problems] Through intensive studies by the present inventors to overcome the drawbacks of conventional thickening and gelling agents, an ethylenically unsaturated acid monomer It has been discovered that a copolymer whose main constituent monomers are a vinyl monomer containing an amino group reacts extremely sensitively to changes in the pH of the system, and can thicken and gel an aqueous dispersion in a desired pH range. , the present invention was completed. That is, the present invention relates to a thickener characterized by being composed of a copolymer whose main constituent monomers are an ethylenically unsaturated acid monomer and an amine group-containing vinyl monomer.

The present invention will be explained in further detail.

Ethylenically unsaturated acid monomers in the present invention specifically include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, and maleic acid, vinylsulfonic acid, styrenesulfonic acid, Unsaturated sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid, mono(2-acryloyloxyethyl)acyl, dophosphate, mono(2-methacryloyloxyethyl)
These include phosphoric acid group-containing vinyl monomers such as acid phosphate.

The amino group-containing vinyl monomer in the present invention specifically refers to methylaminoethyl (meth)acrylate, ethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, dimethylaminoethyl (
Aminoalkyl esters of ethylenically unsaturated carboxylic acids such as meth)acrylate, diethylaminoethyl(meth)acrylate, dimethylaminopropyl(meth)acrylate, methylaminoethyl(meth)acrylamide, dimethylaminoethyl(meth)acrylamide, dimethylamino Aminoalkylamides of ethylenically unsaturated carboxylic acids such as propyl (meth)acrylamide, aminoalkyl vinyl ethers such as aminoethyl vinyl ether, methylaminoethyl vinyl ether, dimethylaminoethyl vinyl ether, 2-vinylpyridine,
These include vinylpyridines such as 4-vinylpyridine.

The ratio of the combination of the ethylenically unsaturated acid monomer and the amino group-containing vinyl monomer, which are the main constituent monomers of the copolymer of the present invention, is as follows: It is preferable to use them together so that the ratio of the equivalent A to the equivalent B of the amino group in the amine group-containing vinyl monomer is 0.1≦A/B (1, more preferably 0.2≦A /B≦0.7.If A/B≧1, even if the pH of the system is lowered, the viscosity will increase,
The gelation effect is small, and when A/B <0.1, high p
Even in the H range, the system tends to thicken and gel during addition, which is unfavorable in terms of handling.

The copolymer in the present invention can be easily produced by polymerizing the ethylenically unsaturated acid monomer and the amine group-containing vinyl monomer, or a mixture thereof with other polymerizable monomers, using known techniques. can be obtained. For example, the known aqueous solution polymerization, that is, the above monomer mixture is carried out at 50 to 150°C in alcohol, water, or a water/alcohol mixed solvent using a common polymerization initiator in an amount of 0.1 to 10% by weight based on the total monomers. So 3~
A copolymer can be obtained as a solution with a predetermined concentration by carrying out a polymerization reaction for 5 hours and removing a portion of the solvent if necessary.

The copolymers of the present invention include those containing polymerizable monomers other than ethylenically unsaturated acid monomers and amino group-containing vinyl monomers as a third component. Specific examples of monomers include alkyl esters of acrylic acid or methacrylic acid, hydroxyalkyl esters, polyalkylene glycol monoacrylates, polyalkylene glycol monomethacrylates, acrylamide, styrene, vinyl acetate, acrylonitrile, etc. One or more of these are used in combination with the above monomers. The proportion of the combined use is preferably 20% by weight or less based on the total monomers. If the combined use exceeds 20% by weight, thickening and gelling effects will be observed, so it is preferable to avoid this.

The gel point of the thickener of the present invention can be adjusted by the type and amount of the ethylenically unsaturated acid monomer constituting the copolymer and the type and amount of the amino group-containing vinyl monomer.

The thickener of the present invention can be mixed into an aqueous dispersion at a pH above the gelling point, and then the system can be thickened and gelled by lowering the pH. In the pH range above the gelling point, even if the thickener of the present invention is mixed, the aqueous dispersion will not thicken or gel, and the aqueous dispersion will remain stable. Possible methods for lowering the pH include adding acidic substances and removing alkaline substances from the system. However, when volatile alkaline substances such as ammonia are used to adjust the pH, the alkaline substances are volatilized by heating. By letting p of the system
Since it can lower H, it can be used under the same conditions as conventional so-called heat-sensitive gelling agents.

Examples of aqueous dispersions to which the thickening and gelling agent of the present invention are applied include natural and synthetic latexes, various synthetic resin emulsions, aqueous slurries of inorganic and organic substances, and mixed compositions thereof. Can be mentioned.

[For production]

The thickening agent of the present invention, which is made of a copolymer mainly composed of an ethylenically unsaturated acid monomer and a vinyl monomer containing a 7-mino group, can maintain aqueous dispersion from low viscosity to low viscosity in a wide pH range. It can be adjusted to a wide range of viscosities, including high viscosity and even gelation, and it is easy to design the pH range where viscosity increases and gelation starts. It has high pH response sensitivity and is free from coexisting substances such as surfactants and electrolytes. It exhibits an excellent effect of being able to keep the aqueous dispersion stable in the pH range above the gelation point and is not easily affected. [Example] The present invention will be specifically explained below with reference to Examples. However, the present invention is not limited to these examples. In addition,
Parts and percentages in Examples and Comparative Examples are based on weight. The properties of the copolymers used in the test are shown in Table-1. The abbreviations used in the table indicate the following substances.

AA Niacrylic Acid, MAA: Methacrylic Acid, AMPS
: 2-acrylamido-2-methylpropanesulfonic acid, PA: mono(2-acryloyloxyethyl) acid phosphate, DMAEMA dimethylaminoethyl methacrylate, DMAPAAm dimethylaminopropane acrylamide, 4-VP: 4-vinylpyridine Table- 1 Examples 1 to 4, Comparative Examples 1 to 2 Acrylic latex for adhesive processing (Primer A/N-580 manufactured by Rohm and Haas, solid content 54.8%,
Viscosity 75 cp pH 7.8) was adjusted to a predetermined DH with aqueous ammonia and hydrochloric acid in the range of pH 8.0 to 1 tO. As a thickener, copolymers 1.2.5 shown in Table 1 are used.
6 was added at 2% of the solid content of the latex,
After mixing thoroughly, adjust to the specified pH with aqueous ammonia and hydrochloric acid.
was readjusted. Measure the viscosity of the dispersion using a B-type viscometer (1
2-60 rpm, 25°C, 60 seconds). The results are shown in Table-2.

In addition, Table 1 shows the case where no thickener is added and the thickener.
Table 2 also shows the results when Copolymer 9 shown in Table 2 was added.

Table 2 shows that the copolymer of the present invention does not thicken the latex in the pH range above the gelling point, but can rapidly thicken and gel in the pH range near the gelling point, and
It can be seen that the gel point can be controlled by changing the composition of the copolymer.

Examples 5 to 8, Comparative Examples 6 to 4 Alumina (AL-j60sG manufactured by Showa Light Metal ■) 100
Sodium polyacrylate (Toagosei Chemical Industry ■#!
A-6114 Solid content: 40 cm Viscosity: 250 cp pH
8,5) was added with 5 parts of L and 24.5 parts of distilled water and pulverized for 24 hours in a ball mill to prepare an aqueous dispersion of alumina with a solid content concentration of 80%, a viscosity of 190 cp, and a pH of 9.5. .

The resulting aqueous dispersion was adjusted to pH 9 with aqueous ammonia and hydrochloric acid.
, 0 to 110. As a thickener, α3 times of copolymers 2, 6, and 4.7 shown in Table 1 were added to the solid content of the slurry, and after thorough mixing, the mixture was adjusted to the specified pH again with aqueous ammonia and hydrochloric acid. It was adjusted. Measure the viscosity of the dispersion using a B-type viscometer (12 to 6 Or
pm, 25°C, after 60 seconds). The results are shown in Table-3.

In addition, when no thickener is added and as a thickener, Table-I
Table 3 also shows the results when Copolymer 9 with K was added.

Table 6 shows that the copolymer of the present invention does not thicken the pigment slurry in the pH range above the gelling point, but can rapidly thicken and gel the pigment slurry in the pH range near the gelling point. It can be seen that the gel point can be controlled by changing the composition of the copolymer.

Examples 9 to 10 Vinyl acetate-ethylene latex for carpet, dopa, and king (manufactured by Sumitomo Chemical Co., Ltd. Sumikafre, Kusu 850
Solid content 50%, viscosity 280cpppH5,6) 100 parts,
Heavy calcium carbonate (manufactured by Nitto Funka Kogyo 88#50)
250 parts, sodium pimyate a 15 parts, distilled water 4985
Thoroughly mix the parts to obtain a solid concentration of 75% and a viscosity of 220 cp.
A carpet backing adhesive composition having a pH of 92 was prepared. Aqueous ammonia is added to the resulting composition to
Adjusted to H1α0. Copolymer 2 in Table 1 as a thickener
．． 8 is added at α5% based on the solid content of the composition,
After mixing thoroughly, adjust the pH to 100 with aqueous ammonia and hydrochloric acid.
was readjusted. After heating the sample dispersion in a 60°C water bath for a predetermined time, the sample dispersion was immediately cooled to 25°C to determine the viscosity and p of the dispersion.
H was measured. The results are shown in Table-4.

Example 11. Comparative Example 5 Example 9 except that the aqueous dispersion was adjusted to pH 1to and Copolymer 4 in Table 1 was used as a thickener.
It was carried out in the same manner as in 10. The results are shown in Table-4.

Table 4 also shows the results when no thickener was added.

From Table 4, the thickener of the present invention can thicken and gel an aqueous dispersion by removing volatile alkaline substances such as ammonia by heating and lowering the pH of the aqueous dispersion. It can be seen that it can also be used as a type of heat-sensitive gelling agent.

Comparative example 6 It can be seen that there is a significant difference.

100 parts of silicone-modified polyether heat-sensitive coagulant (manufactured by Toshiba Silicone ■)
TPA4390 cloud point 50℃ active ingredient 33%) 12
After adding 8 parts and thoroughly mixing, the temperature of the dispersion was raised from 25°C to 70°C and the change in viscosity was measured. The results are shown in Table-5.

Comparative Example 7 A silicone-modified polyether heat-sensitive coagulant (Comparative Example 7) was added to 100 parts of the acrylic latex used in Examples 1 to 4.
Comparative Example 6 was carried out in the same manner as in Comparative Example 6, except that 33 parts of α was added. The results are shown in Table-5.

Table 5 shows that the silicone-modified polyether heat-sensitive coagulant has a thickening and gelling effect on acrylonitrile-butadiene latex, but almost no effect on acrylic latex. (11) Effects of the Invention According to the present invention, the coagulation effect is significant depending on the type of aqueous dispersion.

It is an excellent thickener that has a low viscosity when added, can thicken or gel the aqueous dispersion by adjusting the DH, and the thickened or gelled aqueous dispersion is stable. This will greatly contribute to industries that manufacture and use adhesives, pressure-sensitive adhesives, paints, inks, sealants, etc. that use aqueous dispersions such as latex, emulsions, water-based paints, and pigment slurries. be.

Claims (1)

[Claims] 1. A thickener comprising a copolymer whose main constituent monomers are an ethylenically unsaturated acid monomer and an amino group-containing vinyl monomer.