JPH073171A - Coating composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a coating compsn. improved in stability by polymerizing a radical-polymerizable monomer in the presence of a chain transfer agent having a specific hydrolyzable silyl group. CONSTITUTION:A coating compsn. contg. a stably dispersed acryl-silicone resin having hydrolyzable silyl groups of formula II at molecular ends is obtd. by putting a suitable amt. of water into a reactor, adding dropwise a mixture comprising radical-polymerizable unsatd. monomers, such as methyl methacrylate and n-butyl acrylate, and a chain transfer agent having a hydrolyzable silyl group of formula I (wherein R<1> is an org. group; R<2> is a hydrolyzable group; R<3> is H, alkyl, or aryl; and n is 1-3) (e.g. 3-mercaptopropyltrimethoxysilane) in an amt. of the agent of 50mol% or lower of the total amt. of the monomers to water under stirring, adding dropwise a water soln. of a radical-polymn. initiator, such as ammonium persulfate, when about 10% of the above-mentioned mixture is added, adding the rest of the mixture while keeping the temp. of the reaction system at 80-90 deg.C, continuing stirring for a certain time, and cooling the system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel acrylic silicone-based coating material composition having a hydrolyzable silyl group at the terminal of the main chain of the molecule and having excellent chemical resistance, weather resistance, adhesiveness and stability, and its production. Regarding the method.

[0002]

2. Description of the Related Art In recent years, acrylic silicone resin is a resin having high weather resistance and chemical resistance equivalent to that of fluorocarbon resin, which has already been proven, for exterior building materials, automobiles, metal / wood / plastic processed products, and heavy It has been used for various coating applications such as anticorrosion. Acrylic silicone resin is characterized in that the acrylic resin, which has already been proven in terms of properties such as weather resistance, chemical resistance, and waterproofness, is used as the base material and the chemical characteristics of the silicone compound are incorporated to give it high functionality. The most significant feature is that it has a hydrolyzable silyl group such as trimethoxysilyl group or triethoxysilyl group at the terminal of the side chain of the molecule. This hydrolyzable silyl group (or silanol group in the already hydrolyzed form) forms a siloxane bond with excellent chemical stability after being applied to the substrate and then hydrolyzed by moisture in the air, followed by a condensation reaction. Therefore, the crosslinking reaction between the coating resin molecules becomes possible. That is, the acrylic silicone resin has the unique property of being a one-liquid room temperature curable resin, which is unique to other coating material resins. In addition, another characteristic of the acrylic silicone resin is that it has excellent affinity (adhesion) with the substrate. The fact that the hydrolyzable silyl group has excellent affinity (adhesion) with the substrate, especially with the surface of the inorganic material means that various compounds having the hydrolyzable silyl group can be used as a silane coupling agent in a very wide range of material surfaces. Proven in use for reforming.

[0003]

However, when the stability as a coating material is a problem, the high reactivity of the hydrolyzable silyl group (that is, the intermolecular reaction due to the condensation reaction), which is the point of high functionality of the acrylic silicone resin, is exhibited. The reactivity of the condensation reaction) suffered, and improvement in storage stability, pot life, workability, etc. remained as an issue.

Conventional acrylic silicone resins are produced by radical polymerization using vinyl having a hydrolyzable silyl group or acrylic monomer as a copolymerization component. In this case, since the hydrolyzable silyl group is introduced into the molecule in multiple and randomly at the side chain end, it is impossible to control the introduction site, and as it is, it is possible to suppress the intermolecular condensation reaction in the pretreatment stage. Very difficult. As a result, the following two measures have been taken as measures to ensure stability.

The use of a hydrolyzable silyl group having a low reactivity to reduce the number of condensation reaction points is a method of minimizing the amount of the hydrolyzable silyl group introduced. Is a method in which a bulky substituent is used as a substituent on a silicon atom to prevent the attack of a nucleophile (water) from approaching or a substituent having a low reactivity in elimination reaction is used. In all of these methods, the point is to reduce the reactivity of the hydrolyzable silyl group, so of course the reactivity of the coating film formation (condensation crosslinking reactivity) and the physical properties of the coating film must be sacrificed. There is.

In the field of civil engineering and construction, workability,
From the viewpoint of environmental protection, the development of water-based coating materials of acrylic silicone resin is eagerly awaited.
No. 18676, a side chain type acrylic silicone resin is produced by a solution polymerization method using a water-soluble solvent, and then an amino group in the resin is neutralized with an acid to disperse it in water. There is an example of producing a water-dispersible side chain type acrylic silicone by emulsion polymerization using a hydrolyzable silyl group-containing vinyl monomer as a copolymerization component such as 181173 and JP-A-3-227312. However, due to the above-mentioned properties of the hydrolyzable silyl group, the former case causes intermolecular condensation in the neutralization reaction process, and the latter case also has a problem in the stability of the obtained emulsion. At present, there is no established method for producing a water-based acrylic silicone having excellent stability.

Therefore, the present invention aims to solve the above problems of the conventional acrylic silicone resin, and a novel composition for acrylic silicone coating material having excellent stability and high efficiency capable of coping with water-based composition. It is to provide the manufacturing method.

[0008]

The present invention has the following constitution in order to achieve the above object.

[(1) In a composition for a coating material comprising a polymer of monomers having a polymerizable multiple bond, at least one molecular terminal has the general formula:

[Chemical 3] (Wherein R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is at least one substituent selected from hydrogen, an alkyl group and an aryl group, and n is an integer of 1 to 3). A composition for a coating material, which has a degradable silyl group.

(2) The following general formula

[Chemical 4] (Wherein R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is at least one substituent selected from hydrogen, an alkyl group and an aryl group, and n is an integer of 1 to 3). The method for producing a coating material composition according to claim 1, wherein the radically polymerizable monomer is polymerized in the presence of a chain transfer agent having a degradable silyl group. In view of the above-mentioned object, the present inventors, if the present inventors can control the introduction site of the hydrolyzable silyl group at the terminal of the main chain of the molecule, without reducing the reactivity of the hydrolyzable silyl group. It was considered that an acrylic silicone-based coating material composition having excellent stability could be obtained. Therefore, as a result of earnest research, it was possible to selectively introduce the hydrolyzable silyl group into the terminal of the main chain of the molecule by polymerizing the radical-polymerizable monomer in the presence of the chain transfer agent having the hydrolyzable silyl group. It has been found that a novel acrylic silicone-based coating material composition having excellent properties can be obtained, and that the production method of the coating material composition can easily be applied to the production of a corresponding aqueous composition. Hereinafter, the present invention will be described in detail. For simplification of description, a conventional acrylic silicone having a hydrolyzable silyl group, which is produced by radical polymerization using a vinyl having a hydrolyzable silyl group or an acrylic monomer as a copolymerization component, and has a hydrolyzable silyl group only at the molecular side chain end. The resin is described as "side chain type acrylic silicone", and the novel acrylic silicone resin having a hydrolyzable silyl group at the terminal of the main chain of the molecule of the present invention is described as "main chain type acrylic silicone".

First, the polymer to which the hydrolyzable silyl group is introduced in the present invention is not particularly limited, but a polymer produced by radical polymerization of a monomer having a radical-polymerizable multiple bond is preferable. . The radical polymer may be either a homopolymer of monomers exemplified below or a copolymer composed of several monomer components.
Examples of the monomer used include (meth) acrylic acid and acid derivatives thereof, and vinyl monomers. As the (meth) acrylic acid derivative, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate, 2-
Examples thereof include esters such as hydroxyethyl methacrylate and N, N-dimethylaminoethyl methacrylate, amides such as acrylamide, methacrylamide, and N-methoxymethylacrylamide, and acid anhydrides such as maleic anhydride. Examples of vinyl-based monomers include styrene, vinyltoluene, methyl vinyl ether and vinyl acetate. In addition, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, 3- (trimethoxysilyl) propylmethacrylate, 3- (dimethoxymethylsilyl) propyl used in the conventional production of a side chain type acrylic silicone resin. A monomer that shares a polymerizable multiple bond with a hydrolyzable silyl group such as methacrylate can also be used, and it is possible to introduce a hydrolyzable silyl group into both the main chain and side chain terminals, and the required characteristics The content of the hydrolyzable silyl group can be changed according to the above. Further, an emulsifier having a radical-polymerizable multiple bond can be used as a radical copolymerization component. The use of such a reactive emulsifier is not only effective in controlling the "wettability" of the coating film, but also particularly effective in producing a water-based acrylic silicone-based coating material.
That is, by using the reactive emulsifier, the emulsifying active ingredient is introduced into the acrylic silicone molecular chain through a chemical bond, so that the water dispersibility and stability of the water-based acrylic silicone resin are improved. Further, the water resistance of the cured coating film of the water-based acrylic silicone resin is dramatically improved as compared with the case where the non-reactive emulsifier is used. Examples of such reactive emulsifiers include polyoxyethylene compounds having radically polymerizable multiple bonds represented by alkenyl groups such as vinyl group and propenyl group, carboxylate salts, sulfate ester salts, amine salts, ammonium salts, etc. Any radical-polymerizable multiple bond and a structural part having an emulsifying action in the same molecule can be used, and the structural part is not particularly limited.

The point that the novel main chain type acrylic silicone-based coating material composition of the present invention is decisively different from the conventional side chain type acrylic silicone is that the hydrolyzable silyl group represented by the formula (1) is at the main chain terminal. It has been introduced. Formula (1) will be described in more detail.

R ¹ is an organic group such as an alkylene group or an ether bond-containing alkylene group, and is a hydrolyzable silyl group existing in the same molecule, an alkyl group which does not react with a mercapto group, an alkoxyl group, an ester group, or the like. It may have a substituent. Preferred examples include dimethylene group, trimethylene group, tetraethylene group and the like.

R ² which is a hydrolyzable group is a substituent which, when bonded to a silicon atom, can be easily hydrolyzed and converted into a silanol group. Specific examples thereof include an alkoxyl group and a halogen group. It may be a hydroxyl group. n
Is a number from 1 to 3, but the type of R ² may be one of the substituents listed in the specific examples, or a plurality of types may be mixed. The alkoxy group preferably has 1 to 10 carbon atoms,
More preferred are methoxy group and ethoxy group.
The halogen group is preferably a chloro group or a bromo group.

R ³ is selected from hydrogen, an alkyl group and an aryl group, and may be one kind or a mixture of plural kinds. The alkyl group and the aryl group may have a substituent which does not react with the hydrolyzable silyl group and the mercapto group existing in the same molecule. Preferred as the alkyl group is one having 1 to 5 carbon atoms, which may be linear or branched. Most preferably, they are a methyl group and an ethyl group. Preferable examples of the aryl group include a phenyl group, a tolyl group, a xylyl group and the like, and among these, the phenyl group is most preferable.

The form of the novel main chain type acrylic silicone coating composition in the present invention may be either an organic solvent type or an aqueous type represented by a water dispersion type or an emulsion type.

Next, a method for producing the novel main chain type acrylic silicone coating composition of the present invention will be described. The key point of the present invention is to radically polymerize a mercaptan compound having a structure represented by the formula (2) in order to selectively introduce the hydrolyzable silyl group represented by the formula (1) into the terminal of the main chain of the molecule. It is used as a chain transfer agent. Since the hydrolyzable silyl group is introduced by utilizing the chain transfer reaction, the introduction point is limited to the end of the main chain of the molecule.

The equation (2) will be described in more detail with reference to R
¹ is an alkylene group, an organic group such as an ether bond-containing alkylene group, a hydrolyzable silyl group existing in the same molecule, an alkyl group that does not react with a mercapto group, an alkoxyl group, an ester group, etc. You may have. Preferred examples include dimethylene group, trimethylene group, tetraethylene group and the like.

R ² which is a hydrolyzable group is a substituent which, when bonded to a silicon atom, can be easily hydrolyzed and converted into a silanol group. Specific examples thereof include an alkoxyl group and a halogen group. It may be a hydroxyl group. n
Is a number from 1 to 3, but the type of R ² may be one of the substituents listed in the specific examples, or a plurality of types may be mixed. The alkoxy group preferably has 1 to 10 carbon atoms,
More preferred are methoxy group and ethoxy group.
The halogen group is preferably a chloro group or a bromo group.

R ³ is selected from hydrogen, an alkyl group and an aryl group, and may be one kind or a mixture of plural kinds. The alkyl group and the aryl group may have a substituent which does not react with the hydrolyzable silyl group and the mercapto group existing in the same molecule. Preferred as the alkyl group is one having 1 to 5 carbon atoms, which may be linear or branched. Most preferably a methyl group,
It is an ethyl group. Preferable examples of the aryl group include a phenyl group, a tolyl group, a xylyl group and the like, and among these, the phenyl group is most preferable.

Examples of hydrolyzable silyl group-containing mercaptan compounds satisfying the above conditions are 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyldimethylmethoxy. Silane, 3-mercaptopropyltrichlorosilane, 3
-Mercaptopropylmethyldichlorosilane, 3-mercaptopropylphenyldichlorosilane, 3-mercaptopropyldiphenylmethoxysilane, 3-mercaptopropylhydroxydimethylsilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethylmethyldiethoxysilane and the like. To be Preferred are 3-mercaptopropyltrimethoxysilane and 3-mercaptopropylmethyldimethoxysilane.

This method can be applied to all polymers or oligomers synthesized by homopolymerization of monomers having a polymerizable multiple bond or copolymerization of a plurality of monomers used in general radical polymerization.

In the present invention, a hydrolyzable silyl group-containing mercaptan compound represented by the formula (2) is added as a chain transfer agent at the time of polymerization of the above-mentioned monomers having a polymerizable multiple bond, and the polymerization is carried out by adding them. But
The amount is preferably 100 mol% or less based on the total amount of the monomers. The content is more preferably 50 mol% or less, and if the reaction is performed in excess of 50 mol%, the stability of the coating material composition tends to be insufficient. When a monomer having a hydrolyzable silyl group and a polymerizable multiple bond such as vinyltrimethoxysilane is used as the monomer, the amount thereof is preferably 50 mol% or less based on the total amount of the monomer. The content is more preferably 10 mol% or less, and if the reaction is carried out at more than 10 mol%, gelation may occur during the reaction or the stability of the coating material composition tends to be insufficient.

As the radical polymerization method, any one of solution polymerization, emulsion polymerization, suspension polymerization and bulk polymerization may be used. What is particularly important is that the production method of the present invention can be applied to emulsion polymerization, as will be shown later in Examples, and thereby a stable water-based acrylic silicone coating material can be produced. In addition, by using the reactive emulsifier as the radical copolymerization component as described above, it is possible to obtain a water-based acrylic silicone-based coating material having excellent water dispersibility, stability, and good water resistance of the coating film.

As the radical polymerization initiator to be used, any radical polymerization initiator can be used as long as it is compatible with the polymerization method used.
For example, benzoyl peroxide, acetyl peroxide, lauroyl peroxide, t-butyl peroxybenzoate peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide, or a redox type initiator obtained by combining them with a reducing agent, 2,2 ′ -Azobisisobutyronitrile,
2,2'-azobis (2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobisisobutyrate,
2,2'-azobis [2- (2-imidazolin-2-yl) propane], 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazoline) All of general ones such as 2-yl) propane] dihydrochloride and 2,2'-azobis (isobutyramide) dihydrate can be applied.

[0026]

The present invention will be described in more detail by the following examples.

Example 1 A flask equipped with a stirrer, a condenser, a thermometer, and an N ₂ gas inlet tube was charged with 5 g of sodium dodecylbenzenesulfonate and 135 g of deionized water and stirred for 8 hours.
Warmed to 0 ° C. Once stabilized, 55 g of methyl methacrylate and 45 n-butyl acrylate as a monomer solution
g, 3-mercaptopropyltrimethoxysilane 8.8
A solution in which g (5 mol% of the total amount of monomers) was mixed was added dropwise from a dropping funnel. When 10% of the total amount of the monomer solution was dropped, a solution obtained by dissolving 3 g of ammonium persulfate in 50 g of deionized water was added dropwise from another dropping funnel as an initiator solution. The time required for dropping is 1 hour for the monomer solution and 1.5 hours for the initiator solution.
During this period, the temperature of the reaction solution was maintained at 80 to 90 ° C. After completion of the dropping, the mixture was stirred at 80 to 90 ° C. for 2 hours and cooled, and then the solid content 38
A weight% emulsion was obtained.

An acid resistance aqueous solution test was conducted on the obtained emulsion as follows.

20% solid content of emulsion with deionized water
The mortar test plate was applied 5 times with a brush. After leaving it for 7 days at room temperature, 0.2 ml of 40% sulfuric acid aqueous solution is spotted on the coating film for 3 days at room temperature, or 6
Heated at 0 ° C. for 1 hour. After the test plate was washed with water and dried, the appearance of the coating film was evaluated in 4 grades from ⊚ to ×.

⊚: No change in appearance ○: Corrosion of coating film Δ: Exposure of base material (mortar surface) ×: Corrosion of base material A water resistance test of the coating film was performed as follows.

20% solid content of emulsion with deionized water
Was applied to a rolled steel plate waterproofed with a primer so that the dry film thickness was about 40 μm. After standing at room temperature for 7 days, it was immersed in warm water at 80 ° C. for 1 hour, and the state of the coating film was evaluated in 3 grades from ◯ to ×.

◯: No change in coating film Δ: Whitening of coating film ×: Damaged coating film The storage stability of the emulsion was evaluated as follows.

The emulsion was evaluated under room temperature conditions after being left for 3 months.

The evaluation results are shown in Table 1 together with the composition of the emulsion.

[0035]

[Table 1] Example 2 An emulsion having a solid content of 35% by weight was obtained in the same manner as in Example 1 except that the amount of 3-mercaptopropyltrimethoxysilane used was 17.7 g (10 mol% of the total amount of monomers). .

Table 1 shows the evaluation results obtained in the same manner as in Example 1 together with the composition of the emulsion.

Example 3 55 g of methyl methacrylate, 45 g of n-butyl acrylate, 11.2 g of 3-mercaptopropyltrimethoxysilyl methacrylate (5 mol% of the total amount of monomers) 3
Using 8.8 g of mercaptopropyltrimethoxysilane (5 mol% of the total amount of monomers), the reaction was carried out by the method described in Example 1 to obtain an emulsion having a solid content of 34% by weight.

Example 4 135 g of deionized water was placed in a flask equipped with a stirrer, a condenser, a thermometer, and a N ₂ gas introduction tube, and heated to 80 ° C. with stirring. When stable, 55 g of methyl methacrylate, 45 g of n-butyl acrylate, 8.8 g of 3-mercaptopropyltrimethoxysilane (5 mol% of the total amount of monomers) as a monomer solution, and α-sulfo-ω- [2- (1- Propenyl) -4-
Nonylphenoxy] poly (20) oxyethylene ammonium salt (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., “Aqualon HS-2
0 ″) 3 g of the mixed solution was added dropwise from the dropping funnel.
When 10% of the total amount of the monomer solution was dropped, a solution obtained by dissolving 3 g of ammonium persulfate in 50 g of deionized water was added dropwise from another dropping funnel as an initiator solution. The dropping time was 1 hour for the monomer solution and 1.5 hours for the initiator solution, during which the temperature of the reaction solution was maintained at 80 to 90 ° C. After the dropping, 80 ~ 90 ℃
After stirring for 2 hours and cooling, an emulsion having a solid content of 41% by weight was obtained.

Table 1 shows the evaluation results obtained in the same manner as in Example 1 together with the composition of the emulsion.

Comparative Example 1 Using a monomer solution of 55 g of methyl methacrylate, 45 g of n-butyl acrylate and 9.3 g of octyl thioglycolate (5 mol% of the total amount of monomers), the reaction was carried out by the method described in Example 1 to give a solid form. A 38% min emulsion was obtained.

Table 1 shows the evaluation results obtained in the same manner as in Example 1 together with the composition of the emulsion.

Comparative Example 2 55 g of methyl methacrylate, 45 g of n-butyl acrylate and 11.2 g of 3-mercaptopropyltrimethoxysilyl methacrylate (5 mol% of the total amount of monomers) were used as a monomer solution to carry out the reaction by the method described in Example 1. Then, an emulsion having a solid content of 38% was obtained.

Table 1 shows the evaluation results obtained in the same manner as in Example 1 together with the composition of the emulsion.

Comparative Example 3 55 g of methyl methacrylate, 45 g of n-butyl acrylate, 22.4 g of 3-mercaptopropyltrimethoxysilyl methacrylate (10 mol% of the total amount of monomers)
Was used as a monomer solution to carry out the reaction by the method described in Example 1, but the reaction solution gelated during the dropping of the monomer, and an emulsion was not obtained.

Table 1 shows the evaluation results obtained in the same manner as in Example 1 together with the composition of the emulsion.

[0046]

Unlike the conventional acrylic silicone resin, the novel acrylic silicone resin of the present invention having a hydrolyzable silyl group at the terminal of the main chain of the molecule has a hydrolyzable silyl group in the general radical polymerization process. It can be easily produced by causing a mercaptan compound to act as a chain transfer agent.

The method for producing a novel acrylic silicone resin of the present invention is particularly useful in the production of a water-based coating material, which was difficult with conventional products, as is apparent from the examples. That is, in the comparison when the same amount of hydrolyzable silyl group is used, in the method of using an acrylic monomer having a hydrolyzable silyl group at the side chain terminal as a copolymerization component of radical polymerization, which is a conventional production method, a comparative example Although there is a problem in the stability of the obtained coating material as shown in No. 3, an emulsion having good stability was obtained in the production of the novel acrylic silicone resin of the present invention (Examples 2 and 3).

In addition, in the acid resistance test, the novel acrylic silicone resin of the present invention gave the best results.

The novel acrylic silicone resin of the present invention having such a hydrolyzable silyl group at the terminal of the main chain is used for a wide variety of coating materials, for example, anticorrosion paint base polymers, water absorption inhibitors for inorganic building materials such as concrete,
It can be used in acid rain resistant paints and fiber modifiers. Further, by utilizing the feature of the production method of the present invention that a silyl group which is a reactive functional group can be introduced at the terminal of the main chain of the molecule, modification of a very wide range of resins produced by a very general radical polymerization, for example, at room temperature It is also useful as a methodology for imparting curability, adhesiveness, weather resistance, chemical resistance and the like.

Claims (4)

[Claims] 1. A composition for a coating material containing a polymer of monomers having a polymerizable multiple bond, wherein at least one of the molecular terminals has the general formula: (Wherein R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is at least one substituent selected from hydrogen, an alkyl group and an aryl group, and n is an integer of 1 to 3). A composition for a coating material, which has a degradable silyl group. 2. The coating material composition according to claim 1, wherein the polymer component is dispersed in an aqueous medium. 3. The following general formula: (Wherein R ¹ is an organic group, R ² is a hydrolyzable group, R ³ is at least one substituent selected from hydrogen, an alkyl group and an aryl group, and n is an integer of 1 to 3). The method for producing a coating material composition according to claim 1, wherein the radically polymerizable monomer is polymerized in the presence of a chain transfer agent having a degradable silyl group. 4. The method for producing a composition for coating material according to claim 3, wherein an emulsion polymerization method is used.