JPH04279685A - Composition for forming antifouling film on silicone rubber elastomer - Google Patents

Abstract

PURPOSE:To provide an organic polymer material capable of forming an antifouling film having excellent antifouling property and softness on a silicone elastomer, and keeping the adhesivity over a long period. CONSTITUTION:The objective composition is produced by compounding a polymer of a (meth)acrylate containing a specific bifunctional hydrolyzable group, a mixed solvent comprising a volatile organic silicon compound and an organic solvent and a curing catalyst at specific ratios.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD OF THE INVENTION The present invention relates to a film-forming composition that forms a uniform flexible film after being applied onto a silicone elastomer and dries, and has excellent stain resistance on the silicone elastomer and its surrounding areas. .

0002

[Technical background of the invention and its problems] Silicone compositions that become rubbery and elastic include (1) a heat-curable silicone rubber composition using an organic peroxide as a vulcanization accelerator, and (2) a platinum-based catalyst. Si-H and Si-CH=C
Addition reaction-curable silicone rubber compositions that utilize an addition reaction with H2 groups, and (3) condensation reaction-curable silicone rubber compositions that cure using the action of moisture in the air at room temperature are known. . These silicone elastomers have excellent properties such as heat resistance, cold resistance, and weather resistance, as well as electrical insulation and nontoxicity, so they are used in a wide range of fields, including the construction industry, electrical machinery industry, and food and medical industry. . Although such silicone elastomers have excellent properties as mentioned above, they have the disadvantage that they are easily charged with static electricity and easily attract dust because the main component, polydiorganosiloxane, is a dielectric material. . For example, when used in architectural sealants and coating materials, which are major fields of use for condensation reaction-curing silicone compositions,
The polydiorganosiloxane that has precipitated not only itself but also the surrounding area attracts dust, resulting in an inconvenience in that the aesthetic appearance is impaired. In order to solve these problems, Japanese Patent Laid-Open No. 56-157464 and Japanese Patent Laid-open No. 5
No. 7-102343 proposes a method of forming a film containing silicone resin as a main component on a silicone elastic body. However, in this method, the antifouling effect was insufficient because the film was composed of silicone resin. In addition, as a method for forming a uniform film using an organic polymer compound other than silicone resin, Japanese Patent Application Laid-Open No. 58-19313
No. 1 and Japanese Unexamined Patent Publication No. 59-227955, however, it is somewhat difficult to form a uniform film on the silicone elastomer with this method, and the adhesion to the silicone elastomer is improved by not using a curing catalyst. is insufficient;
In particular, the method disclosed in JP-A-59-227955 uses a copolymer of a trifunctional unsaturated group-containing silicon compound and a (meth)acrylate compound, so the formed film has poor flexibility and cracks. There were various drawbacks, such as polyorganosiloxane precipitating from the cracked film to the surrounding area and attracting dust.

0003

OBJECTS OF THE INVENTION In order to improve the above-mentioned drawbacks of silicone elastomers, the present inventors have developed an organic material that forms an antifouling film with excellent non-staining properties and flexibility on silicone elastomers. As a result of extensive research into polymer compounds, we have developed bifunctional hydrolyzable group-containing (meth)acrylate polymers, mixed solvents of volatile organosilicon compounds and organic solvents,
We have discovered that by applying a composition consisting of a curing catalyst to a silicone elastomer, it is possible to form an antifouling film that has the desired performance and whose adhesion does not deteriorate over a long period of time. The invention was completed.

0004

[Structure of the Invention] That is, the present invention consists of (A) (1) 99
．． 9-85 mol% general formula

[0005]

[Chemical formula 3]

(wherein R1 is an alkyl group having 4 or more carbon atoms, R2 is a hydrogen atom or a methyl group) (
meth)acrylate compound and (2) 0.1 to 15 mol% general formula

[0007]

[C4]

(In the formula, R3 is a hydrogen atom or an alkyl group, R4 is a monovalent hydrocarbon group, Q is a monovalent hydrocarbon group having 1 to 6 carbon atoms, X is an alkoxy group having 1 to 4 carbon atoms, A hydrolyzable group selected from the group consisting of an alkoxyalkoxy group having 2 to 6 carbon atoms and an oxime group having 2 to 4 carbon atoms. molecular weight of 1,000 to 300,000
Hydrolyzable group-containing (meth)acrylic polymer 100
Part by weight (B) (a) General formula R54Si, R63S
iO(R72SiO)mSiR63,R8Si(OSi
R93)3 or (R102SiO)n (wherein R5~
R10 is the same or different hydrogen atom or alkyl group, m is 0 or a positive number, n is a number of 3 or more), and the boiling point at normal pressure is 70
(b) a volatile organosilicon compound in the range of ~250°C;
It consists of an organic solvent, and the ratio of (a) and (b) is 1:9.
~Mixed solvent mixed at a ratio of 9:1 10~500
The present invention relates to a composition for forming an antifouling film on a silicone rubber elastomer, which contains as an essential component 0 parts by weight (C) and 0.1 to 30 parts by weight of a curing catalyst.

The present invention will be explained in detail below. The (meth)acrylate compound of component (A) (1) used in the present invention is:

0010

[C5]

(In the formula, R1 and R2 are the same as above), and specific examples of such (meth)acrylate monomers include:

0012

[C6]

Esters of acrylic acid and linear or branched alcohols, such as

[0014]

[C7]

Examples include esters of methacrylic acid and straight-chain or branched alcohols such as the following.

Among these (meth)acrylate compounds, R2 is preferably a methyl group from the viewpoint of solubility in organic solvents. Furthermore, in view of the solubility of (B) (a) in volatile organosilicon compounds, R1 needs to be an alkyl group having 4 or more carbon atoms, particularly 4 to 18 carbon atoms.
is preferably an alkyl group. The number of carbon atoms in R1 is 3
If the following or R1 is a hydrogen atom, the flexibility of the film will be poor.

The component (A) (2) used in the present invention has the general formula

[0018]

[Chemical formula 8]

(In the formula, R3, R4, and X are the same as above), and R3 is a hydrogen atom,
Examples include methyl group, ethyl group, propyl group, and butyl group. Further, as R4, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an aryl group such as a phenyl group, a β-phenylethyl group,
Examples include aralkyl groups such as β-phenylpropyl group. Due to the ease of synthesis of these compounds, R3
is preferably a methyl group, and R4 is preferably a methyl group or an ethyl group. Examples of Q include a methylene group, an ethylene group, a propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and a propylene group is preferred from the viewpoint of ease of synthesis and stability. As X, methoxy group,
Examples include ethoxy group, propoxy group, butoxy group, and methoxy group or ethoxy group is preferred from the viewpoint of ease of synthesis. In addition, when the number of hydrolyzable groups X bonded to a silicon atom is 3, not only the wettability of the composition to the silicone elastomer decreases, but also the flexibility of the cured film decreases; It is not preferable to use only one because adhesiveness to the silicone elastic body cannot be obtained.

The hydrolyzable group-containing (meth)acrylate polymer (A) is prepared by treating (1) and (2) in the presence of an organic solvent and a free radical initiator from about room temperature to the reflux temperature of the solvent. temperature, preferably 50-15
It is obtained by reacting at a temperature of 0°C. The type and amount of the solvent used may be the same as the organic solvent in (B) (b) described later.

Azo compounds and organic peroxides can be used as free radical initiators, specifically azobisisobutyronitrile, t-butyl hydroperoxide, cumene hydroperoxide, di-t-butyl peroxide. , dicumyl peroxide, benzoyl peroxide, t-butyl perbenzoate, acetone peroxide and the like. The amount of free radical initiator is not particularly limited, but is from 0.01 to (1) and (2).
Approximately 1% by weight is appropriate.

[0022] When carrying out this polymerization, chain transfer such as n-propanethiol, 1-hexanethiol, 1-decanethiol, benzenethiol, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc. Controlling the molecular weight using an agent is the most suitable method when used in the composition of the present invention.

The ratio of (A)(1) and (A)(2) is (A)
) (1) 99.9 to 85 mol%, (A) (2)
It is necessary that it be 0.1 to 15 mol%. (A)
If the amount of (2) used is less than this range, the adhesion to the silicone elastomer will decrease, which is undesirable, and if it exceeds this range, the formed film will become brittle, which is undesirable.

Further, the molecular weight of the copolymer obtained by (A)(1) and (A)(2) is 1,000 to 300,00.
It must be within the range of 0. Molecular weight is 1,00
If it is smaller than 0, the properties of the desired film will be poor;
If it is larger than 00,000, the solubility of (B) in the mixed solvent will be lost, which is not preferable.

As the organic solvent used in the above reaction, part or all of the organic solvents (B) (b) are used, and these (B) (b) are (B) (a).
A solvent that is inert to the chemical reaction of volatile organosilicon compounds is preferably used, and solvents such as aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated aromatic hydrocarbons such as chlorobenzene, methanol, ethanol, propanol, butanol, etc. Examples include alcohol, esters such as ethyl acetate and propyl acetate, ketones such as acetone, and ethers such as ethyl ether and tetrahydrofuran. The copolymer of (A)(1) and (A)(2) can be obtained by solution polymerization in such an organic solvent. These organic solvents are preferably used to improve the storage stability and workability of the composition of the present invention. In this case, the amount used is 50 to 2,000% by weight, especially 100 to 1,000% by weight based on the total amount of (A)(1) and (A)(2).
Weight percent is preferred. This is because if it is too small, workability will be poor, and if it is too large, good adhesive strength will not be obtained.

Component (B) (a) of the present invention has the general formula R
54Si, R63SiO (R72SiO) mSiR63
, R8Si(OSiR93)3 or (R102SiO
) n (where R5 to R10, m and n are the same as above), and is a volatile organosilicon compound having a boiling point in the range of 70 to 250°C at normal pressure. In the above general formula, m and n are selected so that the compound has a boiling point of 70 to 250°C, and when R6, R7 and R10 are methyl groups, m is a number from 0 to 4 and n is a number from 3 to 6. However, it is not particularly limited as it varies depending on the group bonded to the silicon atom. These compounds are all low molecular weight volatile alkyl polysiloxanes or silanes, including silanes such as dimethyldiethylsilane, trimethylbutylsilane, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane,
Chain siloxanes such as dodecamethylpentasiloxane, 3-trimethylsiloxy-1,1,1,3,7,7,
Branched siloxanes such as 7-heptamethyltrisiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, 1-ethyl-3,3,5,5,7,7-hexamethyl Examples include cyclic siloxanes such as cyclotetrasiloxane. These silanes or siloxanes need to have appropriate volatility, and their boiling point range is from 70 to 250°C. If the boiling point is lower than this, it will scatter early during coating, making it difficult to form a uniform film on the silicone elastomer, while if it is too high, drying properties will be poor, making it difficult to put it to practical use.

As these silanes or siloxanes, methyl-based siloxanes are preferred because of their ease of synthesis, and octamethylcyclotetrasiloxane is particularly preferred from the viewpoints of appropriate volatility and uniform film formation.

The amount of mixed solvent (B) to be used for (A) (meth)acrylate polymer is (A) 10
The ratio of (a) to (b) is 1:9 to 0 parts by weight.
9:1, 10 to 5000 parts by weight, especially 50 to 1
000 parts by weight is preferred. If the amount used is less than this range, the workability will be poor, and if it is too much, it will not be possible to form a sufficient film on the silicone elastomer, which is not preferable. Also, the mixing ratio of (a) and (b) is (a)
If the amount used is less than this range, the compatibility with the silicone elastomer will decrease, making it impossible to form a uniform film, and conversely, if it is more than this, the solubility of the (meth)acrylate copolymer will decrease, making it difficult to use. This is not desirable because it becomes difficult.

Examples of the curing catalyst (C) include dibutyltin dilaurate, dibutyltin diacetate,
Butyltin-2-ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, iron-2-ethylhexoate, lead-2-ethyloctoate, cobalt-2-ethylhexoate, manganese - Metal salts of organic carboxylic acids such as 2-ethylhexoate, zinc-2-ethylhexoate, titanium naphthenate, zinc naphthenate, cobalt naphthenate, zinc stearate; tetrabutyl titanate, tetra-2-ethylhexyl Organic titanate esters such as titanate, triethanolamine titanate, and tetra(isopropenyloxy) titanate; Organotitanium compounds such as organosiloxy titanium and β-carbonyl titanium; γ-aminopropyltriethoxysilane, n-(trimethoxysilylpropyl) ) Aminoalkyl group-substituted alkoxysilanes such as ethylenediamine; Amine compounds and their salts such as hexylamine and dodecylamine phosphate; Quaternary ammonium salts such as benzyltriethylammonium acetate; Alkali such as potassium acetate, sodium acetate, and lithium oxalate Examples include lower fatty acid salts of metals; dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine; guanidine compounds such as tetramethylguanidine; and guanidyl group-containing silanes and siloxane compounds.

The amount of the curing catalyst (C) used is preferably 0.1 to 30 parts by weight per 100 parts by weight of the polymer (A). If the amount used is less than 0.1 parts by weight, not only the adhesion to the silicone elastic body will be reduced, but also the antifouling effect will be reduced, and conversely, if it exceeds 30 parts by weight, not only will the workability be reduced. , which is not preferable because the storage stability after mixing decreases.

The antifouling film-forming composition of the present invention may be applied by any method such as brushing, roll coating, or spraying. Various additives can be used in combination with these compositions to impart desired functions to the film. In other words, colorants such as pigments and dyes, silica, titanium oxide,
Various additives such as fillers such as carbon black, heat and weather resistance imparting agents, flame retardants, etc. can be used in combination depending on the purpose of imparting various functions to the (meth)acrylate copolymer uniformly coated on the silicone elastomer. It is possible.

[0032]

[Examples] The present invention will be explained below with reference to Examples. In addition, parts in Examples indicate parts by weight.

(1) Synthesis of hydrolyzable group-containing (meth)acrylic polymer (polymer solutions P-1 to P-10) The mixture shown in Table 1 was placed in a reaction vessel equipped with a stirrer, a cooler, and a thermometer. A (meth)acrylic unsaturated monomer, an unsaturated group-containing silicon compound, toluene in an amount twice the total amount of these, and others were added and heated at 70°C for 8 hours in a nitrogen gas atmosphere while stirring uniformly. Polymerization was performed. Next, part of the toluene is distilled off along with the low fraction to adjust the non-volatile content to 50%, resulting in a colorless and transparent liquid polymer solution P-1~
P-10 was obtained (P-7 to 10 are comparative products). In addition,
The number average molecular weights of these polymers, measured using GPC, are also shown in Table 1.

Examples 1 to 10 and Comparative Examples 1 to 7 After curing the silicone sealant and silicone elastic coating agent into a sheet with a thickness of 2 mm, coating composition No. 1 of the present invention shown in Table 2 was prepared. -1~ No. -10
and comparative coating composition no. -11~ No
．． -17 was applied by brushing and cured for two weeks at room temperature. At this time, the applicability of the coating composition and the flexibility of the coating sheet in a 90 degree bending test were observed, and the results are shown in Table 3 as Examples 1 to 10. In addition, after the coating sheet has been cured at room temperature for two weeks, it is soaked in warm water at 50℃ for 7 days.
Adhesion was tested by immersion in a day and a peel test, and antifouling effect was tested by observing the adhesion of dust on the coated surface after being left for 6 months in an outdoor exposure test. These results are also shown in Table 3. In addition, Comparative Example 1 is an example using a high molecular weight copolymer synthesized without using a chain transfer agent, and Comparative Examples 2 to 4 are examples using methacrylic unsaturated monomers and unsaturated group-containing which are outside the scope of the present invention. This is an example in which a copolymer synthesized using one or both of silicon compounds is used. Comparative example 5
is an example in which a curing catalyst was not used in combination with a copolymer using an unsaturated group-containing silicon compound containing three hydrolyzable groups in one molecule. In Comparative Examples 6 and 7, coating compositions were prepared without using a mixed solvent system of an organosilicon compound and an organic solvent.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Effect of the invention] According to the present invention, the surface of the silicone elastic body (
It has become possible to uniformly apply a meth)acrylate copolymer film, and therefore it has become possible to overcome various drawbacks of silicone elastomers. That is, by using the composition of the present invention, it is possible to solve the important industrial problem of easy adhesion of dust to room-temperature-curable silicone elastic sealants and coating materials. It has become possible to improve the drawbacks of silicone elastomers, such as by making it possible to apply them uniformly by using them as primers.

Furthermore, the film-forming composition of the present invention has made it possible to utilize uniformly layered silicone elastomer and (meth)acrylate copolymer compositions in various applications that will be produced in the future.

Claims (1)

[Claims] Claim 1: (A) (1) 99.9 to 85 mol% of the general formula [Formula 1] (wherein, R1 is an alkyl group having 4 or more carbon atoms, and R2 is a hydrogen atom or a methyl group) (meth)acrylate compound represented by (2) 0.1 to 15 mol% of the general formula [Formula 2] (wherein, R3 is a hydrogen atom or an alkyl group, R4 is a monovalent hydrocarbon group, and Q is a carbon A monovalent hydrocarbon group having numbers 1 to 6, X is a hydrolyzable group selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, an alkoxyalkoxy group having 2 to 6 carbon atoms, and an oxime group having 2 to 4 carbon atoms. 100 parts by weight of a hydrolyzable group-containing (meth)acrylic polymer with a molecular weight of 1,000 to 300,000 obtained by copolymerizing with an unsaturated group-containing silicon compound represented by B) (a) General formula R54Si, R63SiO(R
72SiO)mSiR63, R8Si(OSiR93)
3 or (R102SiO)n (wherein R5 to R10
are respectively the same or different hydrogen atoms or alkyl groups, m is 0 or a positive number, n is a number of 3 or more), and has a boiling point of 70 to 250 at normal pressure.
It consists of a volatile organosilicon compound in the range of °C and (b) an organic solvent, and the ratio of (a) and (b) is 1:9 to 9:1.
An antifouling film-forming composition for a silicone rubber elastomer, which contains as essential components 10 to 5000 parts by weight of a mixed solvent (C) and 0.1 to 30 parts by weight of a curing catalyst.