JPH03106948A - Composition for forming porous film, porous film, and formation of porous film - Google Patents

Abstract

PURPOSE:To obtain a composition which can form a porous film merely by coating a substrate with it and drying the substrate) by mixing a film-forming aqueous emulsion comprising particles of a silane group-containing synthetic resin and water with a specified amount of colloidal silica. CONSTITUTION:99.5-85 pts.wt. alpha,beta-ethylenically unsaturated monomer is emulsion- polymerized with 0.5-15 pts.wt. acrylsilane or vinylsilane in the presence of an emulsifier and a polymerization catalyst in water to obtain a film-forming aqueous emulsion (A) comprising silane group-containing resin particles of a particle diameter of 0.03-10mum and water. Component A is mixed with a colloidal silica sol (B) which is a colloidally water-dispersed ultramicroparticulate silica sol or an ultramicroparticulate powdery silica and used in an amount of 0.5-30 times the amount necessary to coat the synthetic resin particles in component A and having a particle diameter at most 1/3 of the particle diameter of the synthetic resin particle.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a composition for forming a porous film that forms a porous film with excellent moisture permeability and absorbency by applying it to a substrate and drying it. The present invention relates to a porous film and a method for forming a porous film.

[Prior Art] Synthetic resins can form a uniform, continuous film when applied to a substrate as a solvent solution, aqueous solution, or aqueous emulsion and are dried, so they can be used as paint binders, adhesives, and paper. It is used in a wide range of applications such as processing binders and fiber treatment agents.

The film thus obtained was a uniform, continuous film with high airtightness.

In recent years, these uses have diversified, and not only films with high airtightness but also films with high moisture permeability and absorbency are now required. For example, paints are required to have a film that allows moisture to pass through rather than blocking it. This is because coating films are required not only to be aesthetically pleasing, but also to have higher performance such as dew condensation prevention and humidity control effects.

In addition, when bonding or coating porous substrates such as paper, fibers, or porous films, it is necessary to use a porous adhesive layer or a porous coating layer in order not to destroy the characteristics of the porous substrate. It was necessary to shape it.

Although many synthetic resin binders have been studied and proposed to form films with high moisture permeability and absorbency, a sufficient synthetic resin binder has not yet been obtained. If fine pores could be formed in a film, a film with extremely high moisture permeability and absorbency could be obtained, so a porous film was considered.

Conventionally, as a method for forming a porous film, for example, Japanese Patent Application Laid-open No. 6
As disclosed in Japanese Patent No. 1-79620, for example, a polyolefin such as borinoethylene is made into a sheet by containing -30% by weight or more of an inorganic filler containing one or more alkaline earth metal oxides such as calcium carbonate. The porous coating is created by stretching the sheet in at least one direction.

Furthermore, as disclosed in Japanese Patent Publication No. 61-17852, a vinyl monomer giving a hydrophobic polymer is emulsion polymerized in the presence of a water-soluble or hydrophilic polymer, and the aqueous emulsion is used to form a film-like material. After shaping, the hydrophobic components are extracted with a solvent to create a porous film.

However, all of these porous films require secondary processing such as stretching or extraction after forming the film, so coating and drying processes such as porous coating layers and porous adhesive layers are difficult to apply. It could not be used for that purpose.

[Problems to be Solved by the Invention] A porous film-forming composition that forms a porous film without impairing the properties of the film simply by applying it to a base material and drying it, and a porous film and a porous film. The purpose is to provide 11 film forming methods. [Means for Solving the Problems] That is, the present inventors conducted research on aqueous compositions that quantitatively generate pores during the process of forming a film, and in particular, developed a composition that is a blend of a synthetic resin emulsion and colloidal silica. Focusing on the fact that films obtained from objects have high water permeability, we completed the present invention after extensive research. The present invention has the following features: 1. It consists of a film-forming aqueous emulsion formed from synthetic resin particles containing silane groups with a particle size of 0.03 to 10 μm and water, and colloidal silica whose particle size is 173 or less of the particle size of the synthetic resin particles. The amount of colloidal silica blended is 0.5 to 30 times the amount of coating resin particles in a composition for forming a porous film. 2. 2. The composition for forming a porous film according to claim 1, wherein the film-forming aqueous emulsion is an emulsion obtained by emulsion polymerization of α,β-ethylenically unsaturated it form and acrylic silane or vinyl silane.

3. Acrylic silane or vinyl silane is a silane compound having a methoxy group and/or acetoxy group,
The composition for forming a porous film according to claim 2.

4. The film-forming aqueous emulsion is obtained by emulsion polymerization of an α, β-ethylenically unsaturated monomer and an α, β-ethylenically unsaturated monomer having a functional group, and the emulsion is reacted with the functional group. The composition for forming a porous film according to claim 1, which is an emulsion in which a silane group is introduced into a synthetic resin which is emulsified by reacting a silane compound having the following.

5. The composition for forming a porous film according to any one of claims 1 to 4, wherein the film-forming aqueous emulsion is an emulsion obtained by emulsion polymerization using a polymerizable emulsifier.

6. The composition for forming a porous film according to any one of claims 1 to 5 is applied to a substrate and dried to form a film, and pores whose surface is formed of colloidal silica are arranged in the film. A porous film made of synthetic resin particles coated with colloidal silica. 7. 7. The porous film according to claim 6, wherein the pores formed on the surface of the film by colloidal silica are communicating pores. 8. Claim 6 or 7, wherein the pores formed in the surface formed by colloidal silica arranged in the film consist of independent pores and communicating pores.
Porous film described in. 9. Forming the surface with colloidal silica, characterized in that the composition for forming a porous film described in Item 1 is applied to the surface of the substrate to be protected and dried at a temperature higher than the shell low film temperature. This is a method for forming a porous film with pores. Theoretical explanation of the process by which a porous film is formed simply by applying the composition for forming a porous film of the present invention to a substrate and drying it is not yet fully elucidated, but the present invention Characteristics of the porous film-forming composition are: 1. It is composed of a film-forming aqueous emulsion composed of synthetic resin particles containing silane groups and water, and colloidal silica. 2. The particle size of colloidal silica is 1/3 or less of the synthetic resin particle size. 3. The blending amount of collodyl silicate is 0.5 to 30 (B preferably 1 to 20@) of the amount to coat the resin. Also, the characteristics of the pores of the porous film of the present invention are as follows. 1. The larger the particle size of the synthetic resin particles used, the larger the pores, and the smaller the particle size, the smaller the pores. 2. The pores are surrounded by colloidal silica particles. Based on the above, the inventors of the present invention believe the following: Since synthetic resin particles have silane groups, their surfaces are coated with colloidal silica, and the process in which the synthetic resin particles coated with colloidal silica dries. However, the colloidal silica on the surface of the combined tcvIj resin particles partially inhibits the fusion, creating pores surrounded by colloidal silica, and forming a porous film. Furthermore, as the moisture remaining inside the film is released to the outside of the film through the pores on the surface of the formed film, pores are generated inside the film and communicating pores are formed.The porous film obtained by the present invention An electron micrograph is attached. As is clear from the electron micrograph, the porous film obtained by the present invention is produced by applying the aqueous composition of the present invention to a substrate and drying it, and is a filler-containing film. The porous film of the present invention is completely different from the porous film that is produced by post-processing the film, that is, by spreading the film or eluting the soluble resin particles present in the film. The pores are controlled by the particle size of the synthetic resin particles, and the particle size of the synthetic resin particles is 0.0.
If the value is 3μ1 to 10μ, larger pores will be obtained, and smaller pores will be obtained. In order to obtain uniform pores, it is preferable that the synthetic resin particles have a substantially uniform particle size, and in the case of two or more types of -E having extremely different particle sizes, the pore sizes will also be non-uniform. Synthetic resin particles must contain silane groups, and the silane groups provide sufficient bonding between the synthetic resin particles and colloidal silica particles, but synthetic resin particles that do not contain silane groups cannot achieve this effect. This is not desirable because it cannot be used. The particle size of colloidal silica must be 173 or less than that of the synthetic resin particles, and even if colloidal silica is used with a particle size greater than 1/3, a porous film cannot be obtained. Further, the amount of colloidal silica blended is 0.5 to 30 times, preferably 1 to 20 times, the amount of the lid covering the synthetic resin particles. The amount of colloidal silica that coats the synthetic resin particles is determined by the particle size of the synthetic resin particles and the particle size of the colloidal silica, and indicates how many times the amount of colloidal silica used is the amount that coats the resin particles. The multiple is calculated using the following formula. N=W(si/o)/W(si) N: Multiple of the amount to coat the resin particles W(sl/p) 'Amount of colloidal silica used per 1111 parts of resin W ・Coating 1 part by weight of resin (sl)' Amount of colloidal silica required to do this W-W/W (si) sip W ・mu W of colloidal silica to coat one resin particle; weight of one resin particle 3 w - t7e ◆π●D ●ρp pp π; Circumference DpS Particle size of synthetic resin particles D ・Particle size of colloidal silica particles 81' ρ ・Specific gravity of colloidal silica SI'ρ,; Specific gravity of synthetic resin Coating synthetic resin particles Even if the multiple of the amount to be used is less than 0.5, 3
Even if it exceeds 0, pores cannot be obtained or pores cannot be uniformly obtained.

The film-form or aqueous emulsion composed of a synthetic resin containing a silane group and water used in the present invention is not particularly limited, but can be obtained by emulsion polymerization of α,β-ethylenically unsaturated monomers. An aqueous emulsion is preferred from the viewpoint of particle size. The silane group can be introduced by emulsion polymerization of α,β-ethylenically unsaturated monomer and acrylic silane or vinyl silane, or by emulsion polymerization of α,β-ethylenically unsaturated monomer and α,β-functional group. - A method in which an emulsion obtained by emulsion polymerization of an ethylenically unsaturated monomer is reacted with a silane compound having reactivity with the functional group is preferred.

Examples of the α,β ethylenically unsaturated monomer used in the present invention include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and lauryl acrylate; methyl methacrylate; Methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate; acrylonitrile, methacrylonitrile; styrene, methylstyrene, chlorostyrene; etc. are suitable. It is. Among these, it is particularly good to combine a monomer with a high glass transition temperature and a monomer with a low glass transition temperature.

In particular, methacrylate monomers are mainly used. Furthermore, styrene-acrylic monomers rich in styrene are also preferably used.

Monomers to be copolymerized with the above monomers include unsaturated carboxylic acid esters other than acrylic esters and methacrylic esters, such as methyl crotonate, ethyl crotonate, dibutyl maleate, and diethyl fumarate. or unsaturated polyvalent carboxylic acid esters; vinyl acetate, vinyl dipropionate, vinyl laurate, vinyl stearate, and those branched at the α-1 position such as vinyl bivalate and Beoba (registered trademark of Shell Chemical Co., Ltd.) One or more of vinyl esters such as vinyl esters of saturated carboxylic acids; vinyl chloride, vinylidene chloride, and ethylene.

In addition, the above α,β ethylenically unsaturated monomer contains 20
An α,β ethylenically unsaturated monomer having a functional group can also be used in combination at a weight percent or less. Examples of α, β ethylenically unsaturated monomers having functional groups include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, maleic acid monoester, fumaric acid monoester, etc. unsaturated carboxylic acids or unsaturated polycarboxylic acid derivatives; unsaturated carboxylic acid amides such as acrylamide and methacrylamide; N-methylol unsaturated carboxylic acid amides such as N-methylol acrylamide and N-methylol methacrylamide; Unsaturated glycidyl compounds such as glycidyl acrylate and glycidyl methacrylate; alkylolated unsaturated compounds such as hydroxyethyl acrylate, hydroxyvinyl methacrylate, and hydroxyvinyl ether; one or more of diallyl phthalate, divinylbenzene, or diallyl compounds; There are two or more types.

The acrylic silane or vinyl silane used in the present invention is preferably a hydrous type, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyltriacetoxysilane, γ-methacrylooxypropyltrimethoxysilane, vinyltrichlorosilane,
γ-methoxypyltris(methoxy-ethoxy)silane, etc., but from the viewpoint of non-polymerizability, γ-
-methacrylooxypyltrimethoxysilane and vinyltrimethoxysilane are most preferred.

The appropriate proportion of tit B is 99.5 to 85 parts by weight of the α,β ethylenically unsaturated monomer and 0.5 to 15 parts by weight of the acrylic silane or vinyl silane. Preferably α, β ethylenically unsaturated monomer 98,0 to 90
2 parts by weight of acrylic silane or vinyl silane
．． θ˜10ffif1 part.

In the present invention, to produce a film-forming aqueous emulsion using acrylic silane or vinyl silane, the above-mentioned α,β-ethylenically unsaturated monomer and acrylic silane or vinyl silane are combined in the presence of an emulsifier and using a polymerization catalyst. Obtained by emulsion polymerization. The polymerization method may be a batch method or a continuous feeding method for monomer feeding. Alternatively, a method may be used in which a portion is first polymerized and then the remaining portion is continuously fed. The monomers that are continuously fed in may be fed as they are, but it is extremely suitable to feed them as a monomer emulsion using water and an emulsifier. Further, high temperature polymerization or redox polymerization may be used. In particular, when water resistance is required for the porous film, it is preferable to use a polymerizable emulsifier as the emulsifier. Examples of the polymerizable emulsifier include (1) an alkali salt of alkylarylsulfone succinate (2) sodium (glycerin n-alkenyl succinate) Noylglycerin) borate CHO OH2C 2 \ / B / \ CH-CHCH-CH COOCH2-CHO2 OHC-CH20H COONm Na (Left below) H2C-COOR+ (In the formula, R1 is an alkyl group having 8 to 20 carbon atoms) (3 )
Alkaline salt of sulfoprobyl maleic acid monoalkyl ester HC-COOR3 11 (4) Polyoxyethylene alkyl ester of acrylic acid or methacrylic acid (20 alkyl groups, n is an integer of 1 to 20), and the like.

The appropriate amount of the polymerizable emulsifier used is 0.5 to 10 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts of total monomers.
~5ffi parts.

Emulsification ff! A film-forming aqueous emulsion in which silane groups are introduced by reacting the resulting emulsion with a silane compound is produced by emulsion polymerization of α, β-ethylenically unsaturated monomer and acrylic silane or vinyl silane. Alternatively, it can be produced by blending a silane compound into an emulsion obtained by emulsion polymerization using an α,β-ethylenically unsaturated monomer having a functional group instead of vinylsilane and reacting it.

Aminosilane and/or epoxysilane are used as the silane compound.

Examples of aminosilanes include N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-fluorinated dimethoxysilane. Preferred is 3-aminopropyltrimethoxysilane.

Aminosilanes are particularly effective for aqueous copolymer emulsions into which glycidyl or carboxyl groups have been introduced.

Eboxysilanes include 3-glycidoxybutyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(
3.4 epoxycyclohexyl)ethyltrimethoxysilane is preferred. Eboxysilane is particularly effective for copolymer aqueous emulsions into which amino or carboxyl groups have been introduced. In the present invention, the synthetic resin particles containing silane groups have a higher reactivity with colloidal silica when the silane groups are present near the surface (outside) of the copolymer particles in a larger amount than when the silane groups are uniformly present in the synthetic resin. is preferable because it becomes larger. Therefore, a silane compound having reactivity with the functional group is reacted with an emulsion obtained by emulsion polymerization of an α,β-ethylenically unsaturated monomer and an α,β-ethylenically unsaturated monomer having a functional group. Particularly preferred is an emulsion in which a silane group is introduced into a synthetic resin that is emulsified. Colloidal silica conveniently used in the present invention includes:
Ultra-fine pre-silica sol or ultra-fine powdered silica that has been dissolved in water in colloidal form, both of which have primary particle diameters of R7L. V
The particle size of A-fat particles must be 173 or less, but is particularly preferably 0.01 μm or less. The aqueous composition for forming a porous film of the present invention can form a porous film with excellent moisture permeability and absorbency by applying and drying it to a base material, and the base material is not particularly limited. Drying after application may be done naturally or by artificial heating. The drying temperature is preferably higher than the minimum film formation temperature of the copolymer. The thickness of the film varies depending on the purpose for which the porous film is used.
There are no particular limitations. When using a porous film as a paint coating, a relatively thick film is required, for example 0.1 to 0.5
For printing ink-receiving layers of synthetic resin films with porous coatings, a relatively thin coating of 1 to 5 μm is sufficient.
In addition, the porous film-form composition of the present invention may contain colorants, thickeners,
Preservatives, anti-corrosion agents, fluorescent agents, fragrances, deodorants, etc. can be added as appropriate. [Example] The present invention will now be explained with reference to Examples and Comparative Examples. Actual kneeling example 1 70 parts by weight of butyl acrylate, 30 parts by weight of methyl methacrylate
Parts by weight of the mixed monomer i were dropwise emulsion polymerized into an aqueous solution of 2 parts by weight of sodium alkyl phenyl ether sulfonate dissolved in 107 parts by weight of water, and the remaining monomer mixture was reduced to 5/1. At this point, 5 parts by weight of γ-metachlorooxypyltrimethoxysilane was also added dropwise and emulsion polymerization was carried out to obtain a film-forming aqueous emulsion made of synthetic resin particles containing silane groups and water. The film-form or aqueous emulsion had a solid content concentration of 50% by weight and a resin particle size of 0.6 μm. Solid content concentration 40% by weight in 76 parts by weight (solid content) of film-type water-based emulsion
24 parts by weight (solid content) of an aqueous colloidal silica solution having a particle size of 0.05 μm were added and stirred uniformly to obtain a composition for forming a porous film. The particle size ratio of the composition for forming a porous film was 1/12, the particle size of the synthetic resin particles was 0.6μ, and the amount of colloidal silica blended was 1 times the amount to coat the synthetic resin particles. .

The first electron micrograph of the porous film obtained in Example 1 is
As shown in the figure. According to the present invention, extremely uniform pores are thus obtained.

Example 2 A mixture of 111i consisting of 70 ffili parts of butyl acrylate, 30 ffilik parts of methyl methacrylate, and 1 part by weight of acrylic acid was added to an aqueous solution prepared by dissolving 3 parts by weight of sodium salt of alkylaryl sulfosuccinate in 109 parts by weight of water. , dropwise emulsion polymerization was carried out, and from the point when the remaining amount of the mixed monomers became one-fifth, 5 parts by weight of γ-methacrylate oxyprobyltrimethoxysilane was also dropped and emulsion polymerized,
A film-forming aqueous emulsion composed of synthetic resin particles containing silane groups and water was obtained.

The film-forming aqueous emulsion had a solids concentration of 50% by weight and a resin particle size of 0.08 μm.

Film Formation To 1 part (solid content) of 87 fflf aqueous emulsion was added 13 parts by weight (solid content) of an aqueous colloidal silica liquid with a solid content concentration of 40 ffl volume % and a particle size of 0.003μ, and the mixture was stirred uniformly to form a porous film. A string product was obtained. The particle size ratio of the porous film type material is 1/26, the particle size of the synthetic resin particles is 0.6 μ-, and the amount of colloidal silica blended is 1 times the amount to coat the synthetic resin particles. Ta. The second electron micrograph of the porous film obtained in Example 2 is
It is shown in the figure. According to the invention, the diameter is 0.03μ in this way.
m of extremely uniform pores can be obtained. Example 3 50 parts by weight of styrene, 5 parts by weight of 2-ethylhexyl acrylate
0 parts by weight of the mixed monomers were dropwise emulsion polymerized into an aqueous solution of 1 part by weight of sodium salt of alkylaryl sulposuccinate dissolved in 103 parts by weight of water. 1, 2 parts by weight of vinyltrimethoxysilane was also added dropwise for emulsion polymerization to obtain a film-forming aqueous emulsion composed of silane group-containing synthetic resin particles and water. The film-forming aqueous emulsion had a solid content concentration of 50% by weight and a resin particle size of 1.0 μm. 50 parts by weight (solid content) of the film-forming aqueous emulsion with a solid content concentration of 40% indigo
, colloidal silica aqueous liquid with a particle size of 0.025 μm 50
Parts by weight (solid content) were added and stirred uniformly to obtain a porous film forming assembly. The particle size ratio of the composition for forming a porous film was 1/40, the particle size of the resin particles was 0.6 μm, and the amount of colloidal silica was 10 times the amount to coat the synthetic resin particles. In addition, the third electron micrograph of the porous film obtained in Example 3 was
It is shown in the figure. According to the present invention, the diameter is thus 0.3 μm.
Large, extremely uniform pores are obtained. Example 4 80 parts by weight of ethyl acrylate, 20 parts by weight of methyl methacrylate
A mixed monomer consisting of 1 part by weight and 3 parts by weight of dimethylaminoethyl methacrylate was dropwise emulsion polymerized into an aqueous solution prepared by dissolving 1 part by weight of sodium alkyl phenyl ether sulfonate in 107 parts by weight of water to obtain an aqueous dispersion. Further, 3 g of 2-(3.4 epoxyhexane)ethyltrimethoxysilane was added and mixed to obtain a film-forming aqueous emulsion composed of silane group-containing synthetic resin particles and water.

The film-form or aqueous emulsion had a solid content concentration of 50% by weight and a resin particle size of 1.0 μm. 76f of film-forming aqueous emulsion! Aqueous colloidal silica liquid with a solid content concentration of 40% by weight and a particle size of 0.08μ-24
n parts (solid content) were added and stirred uniformly to obtain a composition for forming a porous film. The particle size ratio of the composite material for forming a porous film is 1/13, and the total
II} The particle size of the I fat particles was 0.6 μm, and the amount of colloidal silica blended was one time the amount that coated the synthetic resin particles. Example 5 80 parts by weight of ethyl acrylate, 20 parts by weight of methyl methacrylate
A mixed monomer consisting of 1 part by weight and 2 parts by weight of glycidyl methacrylate was dropwise emulsion polymerized into an aqueous solution in which 3 parts by weight of sodium salt of alkylaryl sulfosuccinate was dissolved in 108 parts by weight of water to obtain an aqueous dispersion. Then, even more N-
3 parts by weight of (2-aminoethyl)3-aminopropylmethyl-dimethoxysilane was added and mixed to obtain a film-forming aqueous emulsion composed of silane group-containing #M fat particles and water. The film-type aqueous emulsion had a solid content concentration of 50% by weight and a resin particle size of 0.08 μm. 40 parts by weight (solid content) of the film-forming aqueous emulsion had a solid content concentration of 40% by weight and a particle size of 0. 60 parts by weight (solid content) of an aqueous colloidal silica solution of 0.003 μm were added and stirred uniformly to obtain a composition for forming a porous film. The particle size ratio of the porous film type composite material was 1/26, the particle size of the synthetic resin particles was 066 μm, and the amount of colloidal silica blended was 10 times the amount coating the synthetic resin particles. Example 6 50 parts by weight of styrene, 5 parts by weight of 2-ethylhexyl acrylate
A mixed monomer consisting of 0 parts by weight and 2 parts by weight of acrylic acid,
Sodium alkylaryl sulfosuccinate 1 m2
Emulsion polymerization is carried out dropwise into an aqueous solution in which m parts by weight are dissolved in 109 parts by weight of water to obtain an aqueous dispersion, and further 5 parts by weight of 3-glycidoxypropyltrimethoxysilane is added and mixed.
A film-forming aqueous emulsion composed of silane group-containing resin particles and water was obtained. The film-type aqueous emulsion had a solid content concentration of 50% by weight and a resin particle size of 0.6 μm. 71i1 in film form or aqueous emulsion! Part i (solid content) has a solid content concentration of 40% by weight and a particle size of 0. Add 29 parts by weight (solid content) of colloidal silica aqueous liquid with an increase of 0.03 μm and stir uniformly to obtain a porous film-forming composition.The particle size ratio of the porous film-forming composition was 1/1. 200, the particle size of the V14 resin particles was 0.6μ, and the amount of colloidal silica was 20 times the amount to coat the V14 resin particles. Comparative Example 1 A film-forming aqueous emulsion (not containing an aqueous colloidal silica solution) prepared by fjing the synthetic resin particles containing silane groups obtained in Example 1 with water. Comparative Example 2 Colloidal silica aqueous solution used in Example 1. Comparative Example 3 70 parts by weight of the colloidal silica aqueous solution used in Example 1 was added to 30 parts by weight (solid content) of the film-forming aqueous emulsion prepared by coating the silane group-containing synthetic resin particles obtained in Example 2 with water.
A composition prepared by adding parts by weight (solid content) and stirring uniformly. The particle size of colloidal silica is 1/1/1 of the particle size of synthetic resin particles.
1.6, and an electron micrograph of the film obtained in Comparative Example 3, in which the ratio exceeds 1/3, is shown in Figure 4. As is clear from the comparative examples, it is understood that if the constituent elements of the present invention are lacking, only a film without pores will be formed. Comparative Example 4 To 99.8 parts by weight (solid content) of the film-forming aqueous emulsion B obtained in Example 6, 0.2 parts by weight (solid content) of the colloidal silica aqueous solution used in Example 2 was added and stirred uniformly. A string composition. This is a case where the amount of colloidal silica particles that theoretically covers the synthetic resin particles is 1/10. (Test method) Presence or absence of pores: The aqueous composition obtained in the examples and comparative examples was
Nl12 on a 100μ thick polyethylene film
A test film was prepared by coating with a No. 0 bar coater and drying at 50°C for 5 minutes. In addition, this film has a temperature of 24% at room temperature.
It showed exactly the same performance as the one dried for hours. The obtained test film was examined using a scanning electron microscope (JEOL J
Observation was made using SM25S-II). ○: Approximately 0.05 to 0
．． The pores of 2μ diameter are connected. ×: No pores at all; Water resistance of film: The test film obtained above was immersed in room temperature water for 24 hours.
After soaking for a period of time, the presence or absence of blistering, whitening, and peeling was examined. ○: No abnormality. Δ: Whitening. ×: Whitening, blistering, and peeling. Water permeability of leather clothing: The aqueous compositions obtained in the actual knee examples and comparative examples were applied to Ghent paper at a solid content of 20 g/rd, dried at 70°C for 10 minutes, and left at room temperature for 24 hours. A film was formed. Fix the funnel upside down on the membrane, seal the periphery, fill the funnel with water, and measure the amount of water that permeates in 120 seconds.
The water permeability (tr/rd) was determined. 0:8
t/rrf or more
They are summarized in the table. (Left below) (Effects) The #fl material for forming a porous film of the present invention comprises a film-forming aqueous emulsion in which synthetic resin particles containing silane groups and having a particle size of 0.03 μm to 10 μm are coated with water; Consisting of colloidal silica whose particle size is 173 or less of the synthetic resin particle,
The total amount of colloidal silica is tj. 1!1 It is a mixture with strong adhesion to silica, which is 0.5 to 30 times the amount that coats the fat particles, so when it is applied to a substrate and dried, the surface is coated with colloidal silica by the silane groups of the synthetic resin particles. The synthetic resin particles coated with colloidal silica fuse and form a film as they dry, but the colloidal silica on the surface of the synthetic resin particles partially inhibits the fusion and the particles are surrounded by colloidal silica. Pores are formed according to the particle size of the synthetic resin particles, and some or all of them become communicating pores, forming a film with extremely good air permeability. Moreover, since the parts other than the pores are in the form of a film, the properties of the synthetic resin, such as adhesiveness, flexibility, elasticity, and toughness, are not impaired. In addition, since the porous film obtained by the present invention has excellent performance, it can be formed on the back side of synthetic resin film, paper, etc.
It can be used as an ink-receiving layer to improve the receptivity of printing ink. By using it as a paint binder, a paint film with excellent air permeability can be obtained. Also, by applying it directly, you can create a top coat with excellent breathability. Can form an anti-fog layer and an anti-condensation layer. By coating fertilizers and drugs, sustained release properties can be imparted to the water-soluble compounds contained therein.

[Brief explanation of drawings]

Figure 1 is an electron micrograph showing the crystal structure of the porous film obtained in Seikuma Example 1. FIG. 2 is an electron micrograph of the porous film obtained in Example 2, showing no crystalline structure. FIG. 3 is an electronic arI1 photo showing the porous skin crystal #4 obtained in Example 3. FIG. 4 is an electron micrograph showing the crystalline structure of the film obtained in Comparative Example 3. Figure 2 Figure 1 Ime 1 Figure 3

Claims (1)

[Scope of Claims] 1. A film-forming aqueous emulsion composed of water and synthetic resin particles containing a silane group and having a particle size of 0.03 to 10 μm, and a particle size of 1/3 or less of the particle size of the synthetic resin particles. Porous film-forming composition 2 is composed of colloidal silica, and the amount of colloidal silica is 0.5 to 30 times the amount that coats the synthetic resin particles. - The composition for forming a porous film according to claim 1, which is an emulsion obtained by emulsion polymerization of an ethylenically unsaturated monomer and an acrylic silane or a vinyl silane. 3. Acrylic silane or vinyl silane is a silane compound having a methoxy group and/or acetoxy group,
The composition for forming a porous film according to claim 2. 4. A film-forming aqueous emulsion is obtained by emulsion polymerization of an α,β-ethylenically unsaturated monomer and an α,β-ethylenically unsaturated monomer having a functional group, and the emulsion is reacted with the functional group. 2. The composition for forming a porous film according to claim 1, which is an emulsion in which a silane group is introduced into a synthetic resin which is emulsified by reacting a silane compound having a silane compound. 5. The composition for forming a porous film according to any one of claims 1 to 4, wherein the film-forming aqueous emulsion is an emulsion obtained by emulsion polymerization using a polymerizable emulsifier. 6. The composition for forming a porous film according to any one of claims 1 to 5 is applied to a substrate and dried to form a film, and the pores whose surface is made of colloidal silica are formed in the film. A porous film consisting of synthetic resin particles coated with colloidal silica. 7. The porous film according to claim 6, wherein the pores formed in the surface of the film by colloidal silica are communicating pores. 8. Claim 6 or 7, wherein the pores arranged in the film and whose surface is made of colloidal silica are composed of independent pores and communicating pores.
Porous film described in. 9. The composition for forming a porous film according to claim 1,
1. A method for forming a porous film having a surface formed of colloidal silica and having pores, the method comprising coating the surface of a substrate to be protected and drying at a temperature equal to or higher than the lowest film forming temperature.