JPH01230613A - Aqueous resin composition - Google Patents

Abstract

PURPOSE:To obtain an aq. resin compsn. having high water resistance and excellent luster and anti-blocking characteristics by neutralizing a polymer obtd. by soln. polymn. of three kinds of specified monomers with a basic compd. CONSTITUTION:An aq. resin compsn. having water-soluble or water-dispersible characteristics is obtd. by neutralizing a polymer obtd. by the soln. polymn. of 1-50wt.% hydrophobic macromonomer (a) having a radical-polymerizable vinyl group on its one terminal and a number-average MW of 1,000-20,000, 1-30wt.% alpha,beta-unstd. carboxylic acid and 20-98wt.% radical-polymerizable monomers other than said (b) with a basic compd. Examples of the terminal functional group of the macromonomer include (meth)acryloyl and styryl groups. The basic compd. is used in an amt. enough to make the polymer water-soluble or water-dispersible and suitable examples thereof include ammonia and amines as they are volatile basic compd. These basic compd. are pref. used in the form of aq. soln.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention relates to an aqueous resin composition that can be used for various purposes, and the coating film formed from it has high water resistance. The aqueous resin composition of the present invention has excellent gloss and anti-blocking properties, and is useful as a general paint or a gloss coating for paper.

[Conventional technology]

Organic solvent solution type coating agents made of acrylic resin etc. have problems such as fire, explosion risk, poisoning, and air pollution due to organic solvents, so coating agents that use water as a medium (hereinafter referred to as water-based coating agents) are recommended. ) is desired.

However, water-based coating agents generally have problems in that the coating films formed therefrom have poor water resistance and blocking resistance, and also have insufficient gloss.

The above-mentioned problems with water-based coating agents are caused by the emulsifier used to make the polymer used as the coating agent water-soluble or water-dispersible, or the hydrophilic monomer unit introduced into the polymer. In order to solve this problem, a proposal was made to use self-emulsifying water-dispersible acrylic fruit resins and resins that can be dispersed in water without the use of emulsifiers (Tokuko Showa). 62
-61047) and many other proposals have been made, but none of them have reached the point where sufficient titration can be achieved in terms of performance.

The structural units of the polymer used as an aqueous coating agent include units for imparting hydrophilicity and adhesion to substrates, such as (meth)acrylate monomer units, and units for improving gloss, professional resistance, and kinging properties. units such as methyl methacrylate monomer units or styrene monomer units, and units for imparting water resistance and smoothness, such as (meth)acrylic acid alkyl ester units in which the alkyl group has 4 or more carbon atoms. Although it is known that polymer units, etc. are necessary, the polymer for the water-based coating agent in the above-mentioned isobaric solution can be obtained by copolymerizing the above-mentioned various hexamers by a normal radical polymerization method. Therefore,
The copolymer has a random arrangement of monomer units. Since it is a random copolymer, a considerable amount of the hydrophilic units contained in the copolymer are present on the surface side of the coating film, that is, on the side where good water resistance should be provided, and as a result, the random copolymer The current situation is that it is impossible to improve water resistance beyond a certain level with a water-based coating agent consisting of.

(B) Structure of the invention [Means for solving the problem] As a result of intensive study on the above-mentioned problems, the present inventors have found that
A novel aqueous resin composition that is composed of a water-soluble or water-dispersible graft polymer that has a hydrophobic macromonomer with high water resistance as a branch component, and does not require the use of additives such as dispersants or emulsifiers. They discovered this and completed the present invention.

That is, the present invention has (a) a radically polymerizable vinyl group at one end and a number average molecular weight of 1.000 to 2Q, 00
1 to 50% by weight of hydrophobic macromonomers with a
) α,β-unsaturated carboxylic acid 1 to 50% by weight and (C
) An aqueous polymer obtained by solution polymerizing 20 to 98% by weight of a radically polymerizable monomer other than (b) above and imparting water solubility or water dispersibility by neutralizing it with a basic compound. It is a resin composition.

The present invention will be explained in more detail below.

The macromonomer used as one of the polymerization components in the present invention has a radically polymerizable vinyl group at one end,
It is a macromonomer having a number average molecular weight of 1,000 to 20,000, and such a macromonomer can be prepared by a method such as that described in JP-A-57-172901, that is, a reactive method such as a carboxyl group, an epoxy group, or a hydroxyl group. In the presence of a radical chain transfer agent having a functional group and a thiol or the like in one molecule, the monomers described below are radically polymerized to obtain a polymer having a reactive functional group at one end,
After that, it can be produced by a method of reacting with a compound having both a functional group that can react with this functional group and a radically polymerizable double bond, such as glycidyl acrylate, glycidyl methacrylate, etc., or a commercially available macromonomer. For example, Macromonomer AA-6 (polymethyl methacrylate macromonomer having a methacryloyl group at the end) manufactured by Toagosei Kagaku Kogyo 1 can also be used. ' The terminal functional group of the macromonomer includes a (meth)acryloyl group, a styryl group, and other radically polymerizable groups such as a vinyl group. Preferred functional groups are a (meth)acryloyl group and a styryl group.

The monomer to be radically polymerized in the presence of the chain transfer agent is preferably a monomer whose homopolymer or copolymer is water-insoluble.
-8 acrylic acid alkyl esters of alcohols, methacrylic acid alkyl esters of alcohols having 1 to 1 B carbon atoms, hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, styrene, α-methylstyrene,
Examples include monomers such as acrylonitrile, vinyl acetate, vinyl chloride, acrylamide, and methylolacrylamide, which can be used alone or in combination of two or more. By using these monomers, the resin composition according to the present invention forms a coating film with excellent gloss.

When the resulting aqueous resin composition is used as an aqueous coating agent, it is preferable to use a monomer that forms a polymer with a glass transition temperature of 50°C or higher as determined by the following formula, and among them, styrene and/or Methacrylic acid alkyl esters are preferred.

1.2,...n: Type of monomer constituting the polymer portion of the macromonomer Tg: Glass transition temperature ('K) of the macromonomer T9
n: Glass transition temperature ('K) of a homopolymer of n monomer Wn: Use a monomer that forms a polymer with a weight ratio glass transition temperature of n monomer units in the macromonomer of less than 50 ° C. If so, the gloss and blocking resistance of the coating film formed from the resulting aqueous resin composition tend to be insufficient.

The amount of the macromonomer used needs to be 1 to 50% by weight, preferably 1 to 30% by weight, based on the total amount of all polymerization components. If it is used in an amount exceeding 50% by weight, a large amount of unpolymerized macromonomer remains after polymerization and the physical properties of the coating film deteriorate, while if it is less than 1% by weight, gloss and blocking resistance cannot be sufficiently improved.

Next, examples of α,β-unsaturated carboxylic acids that are other polymerization components in the present invention include (meth)acrylic acid, maleic acid, and itaconic acid. By neutralizing with a compound, α,
Acid anhydrides, such as maleic anhydride, which allow the same carboxylate group-containing units to be introduced into the polymer as when β-unsaturated carboxylic acids are used, can be used as well.

The amount of α,β-unsaturated carboxylic acid used must be 1 to 60% by weight, preferably 1 to 20% by weight, based on the total polymerization components. If it is less than 1% by weight, even if the resulting polymer is neutralized with a basic compound, it will not be possible to impart water solubility or water dispersibility to it, while if it exceeds 30% by weight, the water resistance of the coating film will be affected. becomes worse.

Radically polymerizable monomers other than α, β-unsaturated carboxylic acid, which is another polymerization component in the present invention, include:
Styrenic monomers such as styrene, methylstyrene, α-methylstyrene, chloromethylstyrene; vinyl acetate,
Nocarboxylic acid vinyl esters such as hinyl propionate; alkyl vinyl ethers such as propyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether;
Methyl (meth)acrylate, Ethyl (meth)acrylate, Butyl (meth)acrylate, (meth)acrylic acid 2
- (Meth)acrylic esters such as ethylhexyl, lauryl (meth)acrylate, stearyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, etc. meth)acrylamide monomer; vinyl chloride,
Examples include radically polymerizable monomers containing chlorine atoms or fluorine atoms, such as vinylidene chloride, vinyl fluoride, and vinylidene fluoride. When the obtained aqueous resin composition is used as an aqueous coating agent, preferable radically polymerizable monomers include styrene and alkyl groups having 1 carbon number.
~12 (meth)acrylic acid alkyl esters.

The amount of the radically polymerizable monomer other than α, β-unsaturated carboxylic acid used, together with the type of monomer and the macromonomer, is a major factor that influences the properties of the coating film formed from the aqueous resin composition. The optimum amount used varies depending on the type of monomer and the type and amount used of the macromonomer, but the amount used is 20 to 98 polymers based on the total polymerization components.
It is necessary to be within the range of 1. If it is less than 20% by weight, the amount of macromonomer used or the amount of α,β-unsaturated carboxylic acid used will inevitably be too large, resulting in a polymer with a high content of unpolymerized macromonomer or poor water resistance. This results in a polymer that forms a poor coating film. On the other hand, 98
If the weight exceeds jt%, the macromonomer and α.

The amount of β-unsaturated carboxylic acid becomes too small, and physical properties based on them cannot be imparted to the polymer.

When the aqueous resin composition of the present invention is used as an aqueous coating agent, the total amount of styrene monomer units and methyl methacrylate monomer units in the polymer, including the structural units derived from the macromonomer, is It is particularly preferable that the amount is 60% by weight or more based on the total amount of all structural units of the polymer. If it is less than 60% by weight, the coating film tends to have insufficient gloss and anti-polishing and kinging properties.

Further, in applications where the coating film is required to have bending resistance, for example, when used as a paper coating agent, it is preferable that the glass transition temperature of the polymer is less than 60°C; In order to obtain the polymer, 30 to 5 weight t of styrene monomer units or methyl methacrylate monomer units, which are monomer units suitable for improving gloss, anti-polishing and kinging properties, are present. ,
(Meth)acrylates other than methyl methacrylate, such as butyl (meth)acrylate, 2-ethylhexyN
Monomer units such as (meth)acrylate and lauryl (meth)acrylate have a glass transition temperature of 60
It is preferable to coexist so that the temperature is below ℃.

The polymerization of the macromonomer, the α,β-unsaturated carboxylic acid, and the radically polymerizable monomer other than the α,β-unsaturated carboxylic acid must be carried out by a solution polymerization method,
Polymerization solvents used at this time include dioxane, tetrahydrofuran, tesetone, methanol, ethanol,
Water-soluble or hydrophilic organic solvents such as impyropanol and butyl cellosolve are preferred, and these can be used alone or in combination of two or more. They can also be used together.

Polymerization conditions other than the polymerization solvent, ie, temperature, polymerization initiator, polymerization time, etc., and polymerization operations may be determined as appropriate with reference to conventional methods, for example, the conditions method described in Japanese Patent Publication No. 57-54598.

The polymer obtained by polymerization is in the state of an organic solvent solution, and by adding a basic compound to this, some or all of the carboxyl groups in the polymer are neutralized, making the polymer water-soluble. or impart water dispersibility. The amount of basic compound used at this time is sufficient to make the polymer water-soluble or water-dispersible, and types include sodium hydroxide, potassium hydroxide, soda carbonate, ammonia, trimethylamine, triethylamine, etc. are mentioned,
Among them, ammonia and amines are suitable because they are volatile basic compounds, and it is preferable to use such basic compounds in the form of an aqueous solution.

After adding water to the neutralized polymer solution as necessary, the organic solvent is removed by a method such as distillation, and then water is further added to obtain an aqueous resin composition adjusted to the desired solid content concentration. is common.

In addition, if an alcohol-based organic solvent is used, the organic solvent is not completely removed, and an aqueous resin composition containing a portion of alcohol may be used, and such an aqueous resin composition may also be suitable depending on the application. used.

The aqueous resin composition of the present invention has been described above, focusing mainly on its properties as an aqueous coating agent, which is an example of its main use.However, the aqueous resin composition of the present invention can also be used in various uses other than coating agents. It can also be used.

(c) Effects of the Invention The aqueous resin composition of the present invention is composed of a graft polymer that is water-soluble or water-dispersible, and this graft polymer constitutes a branch component that is derived from a hydrophobic macromonomer and has excellent water resistance. For example, when used as a coating agent, the branch components tend to be oriented toward the surface of the coating film, so it has excellent properties not found in conventional water-based resin compositions, such as gloss and anti-blocking properties. Forms an excellent coating film.

The present invention will be explained in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 In a 2t flask equipped with a stirring device, the following raw materials dioxane 5005'r Butyl cellosolve 1005'r Macromonomer 401rAA-+5 (manufactured by Tsukuba Gosei Chemical Co., Ltd.)
Polymethyl methacrylate with terminal methacryloyl group, number average molecular weight 6,000) Methyl methacrylate 1205'r Butyl acrylate 221r Acrylic acid
20Pr azobisisobutyronitrile (hereinafter referred to as 4frAIBN) was charged and polymerized at 75 to 80°C for 10 hours in a nitrogen gas atmosphere. Polymerization rate by gas chromatography is 99% on average
, gel permini-silane chromatography (GP)
The polymerization rate of the macromonomer by C) is 100% M
W was 18,000. While maintaining this polymerization solution at approximately 60°C, 18.95'r of 25% ammonia water was added to neutralize it, and then a portion of the dioxane was distilled off while adding water to give a solid content concentration of 65% by weight. A milky white solution was obtained. pH was 8.5.

Comparative Example 1 The same raw materials as in Example 1 were used, and polymerization was carried out under the same conditions, except that the amount of methyl methacrylate used was 16.05'r and the macromonomer AA-6 was not used. The average polymerization rate was 99 H, and the MW was 20,000. Thereafter, the same neutralization treatment as in Example 1 was performed to obtain a milky white solution with a solid content concentration of 34.5% by weight. pH8
, 4.

[Coating film performance test]

Using the aqueous resin compositions of Example 1 and Comparative Example 1 as coating agents, they were coated onto printing paper using a roll coater so that the amount of coating agent after drying was 45'/m, and immediately heated with an infrared lamp. Drying was performed at 100° C. for 5 minutes. It dried with almost no odor. The physical properties shown in Table 1 of the coating film thus formed on the printed paper were measured by the methods described below.

Next, pressing was performed using a flat press at a pressing temperature of 160° C., a pressing pressure of 4.5 ky/cyf, and a pressing time of 20 seconds. The comparison example from the press was a little sticky. The evaluation results for each physical property are shown in Table 1. It can be seen that the effect of the macromonomer used in Example 1 clearly appears in the physical properties of the coating film.

Table 1. Paint film properties The measured values of the physical properties shown in the table were determined by the following methods.

1) Glossiness: 60° specular glossiness was measured in accordance with JIS K5400.

2) Blocking resistance...combined coated surface and coated surface 2
150 for one test piece? /C! Applying a load of It, 45
It was left for 24 hours at 90% RH. Thereafter, the test piece was peeled off and judged as follows.

◎: Not bonded.

○: Adhesive, but the coating film does not peel off from the printing paper.

X: Adhesive and the coating film peels off from the printing paper in dots.

3) Scratch resistance: A drawing tester manufactured by Jyuyu Seisakusho was used. Without placing any particular weight on the load surface, a continuous circle was drawn on the coating film with a steel needle attached to it, and the discrimination was made as follows.

◎There are almost no traces of two stitches.

○: A trace of the needle remains faintly.

Δ: Part of the coating film falls off.

4) Adhesion: The coating film was strongly rubbed with a cellophane tape with a finger, which was quickly peeled off, and changes in the coating film were determined as follows.

◎: The paint film surface and the cellophane tape peeled off, and there was no change in the paint film.

○: 10% or less of the coating surface adheres to the cellophane tape.

X: A portion exceeding 10 inches of the coating surface adheres to the cellophane tape.

Example 2 In a 2t flask equipped with a stirring device, the following raw materials Toyaene 2DD7r Isoglobanol 4001Fr Macromono-r-AS-6 (Toagosei 60yr Kagaku Kogyo ■Shitsu, polystyrene with a terminal methacryloyl group, number average molecular weight 6) were added. .000) Stevy 60fr Butyl methacrylate 160yr Acrylic acid 2-
Ethylhexyl 607r methacrylic acid
60i “AIBN
Prepare 4fr and heat to 75-8 under nitrogen gas atmosphere.
Polymerization was carried out at 0°C for 10 hours. The average polymerization rate determined by gas chromatography was 98%; the polymerization rate of the macromonomer determined by GPC was 100%, and the MW was 16,000. While keeping this polymerization solution at about 60℃, 25 thiammonia water 47
．． 47r was added for neutralization, and then a part of toluene and Impropatool were removed by distillation while adding water to obtain a milky white solution with a solid content of 36% by weight.
Met.

Comparative Example 2 The same raw materials as in Example 2 were used, and polymerization was carried out under the same conditions, except that the amount of styrene used was 120 yr and the macromonomer As-6 was not used. The average polymerization rate was 98%, and the MW was 18,000. Thereafter, the same neutralization treatment as in Example 2 was performed to obtain a milky white solution with a solid content concentration of 36% by weight and a pH of 8.4.

[Coating film performance test]

The aqueous resin compositions of Example 2 and Comparative Example 2 were coated directly on a glass plate with a coating rod, and then dried to a film thickness of 50.
Coat it so that it becomes μ and put it in a dryer at 100℃ for 5
After drying for minutes, a resin coating was formed on the glass plate from each aqueous solution. The physical properties of the obtained coating film were evaluated by the following method.

It was applied to a transparent glass plate, and its transparency was determined by oral administration.

The pencil hardness was measured after coating on a surface-treated mild steel plate and drying at room temperature for 7 days.

After applying it to a water-resistant glass plate and drying it at room temperature for 3 days,
Water was placed on the painted surface and changes in the paint film were examined 3 hours later.

As for hardness, a resin coating was formed by applying the resin coating to a surface-treated mild steel plate in the same manner as above.

The evaluation results were as shown below.

Transparency Gloss Water resistance Adhesion Hardness (immediately)

Claims (1)

[Scope of Claims] 1. (a) 1 to 50% by weight of a hydrophobic macromonomer having a radically polymerizable vinyl group at one end and having a number average molecular weight of 1,000 to 20,000; (b) 1 to 30% by weight of α,β-unsaturated carboxylic acid and (c) 20 to 9 radically polymerizable monomers other than the above (b)
An aqueous resin composition obtained by neutralizing a polymer obtained by solution polymerizing 8% by weight with a basic compound to impart water solubility or water dispersibility.