JPS6159321B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous dispersion containing a peroxy group in the molecule and comprising a copolymer of ethylene, vinyl acetate, and a compound represented by the following formula (). The dispersion has excellent film-forming properties, and heating of the coating promotes crosslinking in which radicals are generated by decomposition of peroxide in the chain, making it insolubilized and significantly improving its physical properties. However, R ₁ is a hydrogen atom or a group selected from the group consisting of an alkyl group having 1 to 4 carbon atoms,
R ₂ and R ₃ are groups selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, and R ₄ is a group having 1 to 12 carbon atoms.
represents a group selected from the group consisting of an alkyl group or a cycloalkyl group having 8 to 12 carbon atoms. The compound represented by the formula () is hereinafter referred to as allyl peroxycarbonate. Conventionally, in order to modify the film obtained from an ethylene/vinyl acetate aqueous dispersion by heat treatment, many attempts have been made to copolymerize the film by adding a monomer having a third functional group during emulsion polymerization. For example, there is a method of copolymerizing N-methylacrylamide to make it three-dimensional (Japanese Patent Publication No. 49-23299, Japanese Patent Publication No. 48-39390), copolymerizing glycidyl methacrylate, and opening the epoxy group. Methods for three-dimensionalization (Japanese Patent Application Laid-open Nos. 114435/1980, 125179/1980, 4169/1980), etc. are known. However, when creating a three-dimensional structure using N-methylol acrylamide, the adhesion strength increases and is effective for hydrophilic materials such as cellulose-based materials, but it is not effective for hydrophobic materials. There is also little improvement in oil resistance and water resistance. Furthermore, it has the disadvantage of generating toxic formalin when heated. Furthermore, when copolymerizing glycidyl methacrylate to make it three-dimensional, it is difficult to make it three-dimensional unless a curing agent such as an amine is used, and the use of amines is practically undesirable from the viewpoint of toxicity. A copolymer of allyl peroxycarbonate is disclosed in JP-A-54-47790, and a copolymer with vinyl acetate is known and its use as a grafting agent is described. The present inventors investigated the modification of ethylene/vinyl acetate aqueous dispersions, and found that a modified ethylene/vinyl acetate aqueous dispersion copolymerized with allyl peroxycarbonate added as a third component has a composition within a certain range. It has been found that if the film has an average particle diameter within a certain range, cross-linking is promoted by heating the film after application, which not only significantly improves solvent resistance and adhesive strength, but also does not generate toxic gas. The invention was completed. That is, it is an aqueous dispersion of a polymer consisting of 4.9 to 40.0% by weight of ethylene, 95.0 to 45.0% by weight of vinyl acetate, and 0.1 to 15.0% by weight of allyl peroxycarbonate, and having an average particle diameter of 0.05 to 1.0μ. The present invention will be explained in more detail below. The amount of allyl peroxycarbonate contained in the ethylene/vinyl acetate/allyl peroxycarbonate copolymer used in the present invention must be 0.1 to 15.0% by weight in consideration of its crosslinking effect. If it is less than 0.1% by weight, the degree of crosslinking will be low even when the film is heated, and improvements in solvent resistance and adhesive strength will be insufficient.
Furthermore, as the amount of allyl peroxycarbonate increases, the degree of crosslinking increases, but when it increases to 15% by weight or more, the toughness of the film decreases, resulting in a sharp decline in performance as an adhesive. Furthermore, if the dispersion is left to stand, the viscosity tends to increase due to crosslinking reaction, which is a practical problem. In addition, the ethylene content contained in the polymer is 4.9
~40% by weight is required. Ethylene content
If it is less than 4.9% by weight, the film forming property at room temperature is poor, the crosslinking effect by heat treatment is low, and the water resistance and alkali resistance are also reduced, resulting in insufficient performance as an adhesive. In addition, when the amount exceeds 40% by weight, the molecular weight of the copolymer tends to decrease and the particle size of the dispersion increases, so when the coating film is heated, the effect of improving physical properties due to crosslinking becomes insufficient, and peroxy The significance of adding carbonate is lost. Examples of allyl peroxycarbonates that can be used as a component of the copolymer include t-butyl peroxyallyl carbonate, t-hexyl peroxyallyl carbonate, 1,1,3,3-tetramethylbutyl peroxyallyl carbonate,
These include t-butylperoxymethacrylic carbonate, 1,1,3,3-tetramethylbutylperoxymethacrylic carbonate, and the like. The average particle size of the aqueous dispersion applied to this application is 0.05
It must be within the range of ~1.0μ. It is particularly important to control the particle size to 1.0 μm or less in order to increase the crosslinking efficiency during crosslinking by heating after film formation, and also from the standpoint of storage stability of the dispersion. Furthermore, when the particle size is less than 0.05 μm, the securing layer on the particle surface becomes thin, particularly the stability decreases, and it becomes difficult to use it as an adhesive in practical terms. The method for preparing an aqueous dispersion having the above composition is to disperse vinyl acetate and allyl peroxycarbonate in water under pressure of ethylene in the presence of a surfactant or protective colloid, and use a water-soluble radical polymerization initiator as a catalyst. It can be obtained by copolymerizing. The ethylene content of the copolymer is determined by ethylene pressure, polymerization temperature, stirring conditions, residual monomer concentration, etc. For example, capacity 5,
In a polymerization tank with a 500 rpm stirrer, 1880 g of vinyl acetate,
When 20 g of allyl peroxycarbonate, 2000 g of water, and other stabilizer catalysts are added first, and polymerization is carried out for 4 hours under a pressure of 10 kg/cm ² of ethylene, the ethylene content of the copolymer will be 5% by weight. In addition, in the above case, if vinyl acetate and allyl peroxycarbonate are sequentially added and polymerized for 5 hours under ethylene pressure of 100 kg/cm ² so that there is almost no residual monomer, the ethylene content of the copolymer is It becomes 40% by weight. As the surfactant, nonionic surfactants or anionic surfactants can be used, but the average particle size is 0.05.
In order to obtain a stable dispersion at ~1.0μ, a nonionic activator is suitable and can also be used in combination with a protective colloid. Nonionic surfactants include partial esters of fatty acids and polyols, such as glycerin monostearate, sorbitol monolaurate, partial ethers of long-chain monoalcohols and polyols, ethers of fatty acids and polyethylene polyols, polyethylene oxide condensates, such as, Polyoxyethylene nonyl phenyl ether, polyethylene oxide and polypropylene oxide condensates can be used. As the protective colloid, hydroxyethyl cellulose, carboxymethyl cellulose, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide, etc. can be used. To obtain 100 parts by weight of a dispersion having the average particle size of the present application, the surfactant is used in an amount of 0.5 to 8.0 parts by weight, preferably 1.0 to 6.0 parts by weight. The protective colloid is used in an amount of 1.0 to 10 parts by weight, but when used in combination with a surfactant, 05 to 4.0 parts by weight is appropriate. As the water-soluble radical polymerization initiator, inorganic peroxides such as hydrogen peroxide, barium peroxide, etc., alkali metal persulfates such as potassium persulfate, sodium persulfate, and other alkali metal percarbonates are used. . Under the above conditions, the copolymerization is completed and an aqueous dispersion having a solid content concentration of 50% by weight and an average particle size of 0.05 to 1.0 μm is obtained. It is also possible to obtain a dispersion liquid in which the terpolymer is further copolymerized with a fourth unsaturated compound by the above method, and the effect of the present invention can be achieved if the content thereof is 20% by weight or less. Examples of unsaturated compounds include vinyl esters such as vinyl propionate, vinyl butyrate, and vinyl versatate, acrylic acids such as methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and hydroxyethyl methacrylate. esters, acrylamides such as acrylamide and N-methylolacrylamide, vinyl halides such as vinyl chloride and vinylidene chloride, α-olefins such as propylene, isobutylene, and octene, acrylic acid, crotonic acid, vinylsulfonic acid, allylsulfonic acid or its neutral salts, dibasic acids such as itaconic acid, maleic acid, and fumaric acid or their neutral salts, allyl compounds such as triallyl cyanurate, trimethylolpropane diallyl ether, diallyl phthalate, and epoxy groups such as glycidyl methacrylate. Containing unsaturated compounds, divinyl compounds such as ethylene glycol dimethacrylate, triethylene glycol diacrylate, etc. can be used. The aqueous modified vinyl acetate/ethylene copolymer dispersion obtained as described above can be used to form crosslinks in a post-treatment, thereby improving the ability of nonwoven fabrics that have had insufficient performance with conventional ethylene/vinyl acetate copolymer dispersions. It can be used as a binder for frotzky processing, and although it was inferior to acrylic aqueous dispersions in terms of water resistance and oil resistance, those with a certain range of composition and a certain range of average particle diameter are extremely superior. It has come to show the characteristics that Furthermore, water resistance and oil resistance can be further improved by blending with a monomer or polymer containing two or more unsaturated double bonds and heat-treating the mixture. On the other hand, compared to a product obtained by copolymerizing and crosslinking N-methylolacrylamide with ethylene and vinyl acetate, it has the advantage that it does not cause any pollution due to formalin or the like. In addition, depending on the curing conditions in these cases, some parts may remain uncured, and the hydrophilicity of the methylol group may actually impair water resistance. It does not adhere well to substances. Furthermore, ethylene and glycidyl methacrylate
When a vinyl acetate copolymer is crosslinked, the crosslinking efficiency is poor and sufficient performance cannot be achieved. The aqueous dispersion can be used as a nonwoven fabric binder, fiber treatment agent, flocking agent, paper treatment agent, pulp board impregnation agent, paint vehicle, etc. When used in those applications, the aqueous dispersion of the present application can be blended with other aqueous dispersions. Furthermore, by taking advantage of the crosslinking property caused by heat treatment, it can be blended with other unsaturated compounds and used as a modifier by heat treatment. The present invention will be explained below with reference to Examples, but these Examples are not intended to limit the present invention in any way. Note that percentages are expressed on a weight basis. Example 1 1400g of distilled water and nonylphenyl ether (Nonipol 400 Sanyo Kasei KK) were placed in an autoclave.
), 20 g of hydroxyethyl cellulose (AL-15 manufactured by Fuji Chemical), and 320 g of vinyl acetate, and after purging with nitrogen while stirring at 500 RPM, pressurize the ethylene pressure to 50 Kg/cm ² and reduce the internal temperature to 50°C.
The temperature rises to Polymerization starts immediately when hydrogen peroxide and sodium persulfate are added to the reactor, and at the same time 1,270 g of vinyl acetate and a 70% toluene solution of allyl t-butyl peroxycarbonate are added.
12.6 g was continuously added over 3 hours, and when the residual vinyl acetate monomer became 1% or less, the reaction was stopped, the temperature of the system was lowered, and the product was taken out.
The solid content of the produced emulsion was 52.3%, the viscosity was 59 cp at 60 rpm using a Bruckfield viscometer (the same applies hereafter for viscosity measurement), and the ethylene content in the resin was 20.1%. Furthermore, the particle diameter was observed and measured using an electron microscope, and the average diameter was 0.9μ. The emulsion film produced in this manner was heat-treated at 150°C for 30 minutes, and the results of the strength and elongation of the film and its perclene resistance are shown in Table 2, and the adhesion and perclene resistance of the ester fabric are shown in Table 3. . Example 2 The procedure of Example 1 was repeated except that 12.6 g of a 70% toluene solution of allyl t-hexyl peroxycarbonate was added instead of allyl t-butyl peroxycarbonate. Tables 1, 2, and 3 show the composition of the obtained dispersion, the physical properties of the film, and the effects of heat treatment. Example 3 The same procedure as in Example 1 was repeated except that 12.6 g of a 70% toluene solution of 1,1,3,3-tetramethylbutyl peroxycarbonate was added instead of allyl t-butyl peroxycarbonate. Table 1 shows the composition of the obtained dispersion and the results of physical property tests of the film.
and 2. Example 4 The same treatment as in Example 1 was carried out except that the ethylene pressure was changed to 12 Kg/cm ² instead of 50 Kg/cm ² . Tables 1 and 2 show the composition of the obtained dispersion and the results of physical property tests of the film. Comparative Example 1 In Example 1, 12.6 g of allyl t-butyl peroxycarbonate 70% toluene solution was added to 571 g.
The same process was carried out except that the post-added vinyl acetate was changed from 1,270 g to 870 g. Tables 1 and 2 show the composition of the obtained dispersion and the results of physical property tests of the film. This applies in Example 1 when the peroxycarbonate exceeds the limit value of 15% of the present invention. Although the perpendicular resistance of the film has improved, the strength and elongation have significantly decreased. Comparative Example 2 In Example 1, the ethylene pressure was 50Kg/ ^cm2.
249g of initially added vinyl acetate 320g to 130Kg/ ^cm2
The same process was carried out except that the post-added vinyl acetate was changed from 1,270 g to 886 g. Tables 1 and 2 show the composition of the obtained dispersion and the results of physical property tests of the film. This applies when the ethylene content of the copolymer exceeds the limit value at 43%, and the particle size also exceeds the limit value, but the percrene resistance and strength and elongation of the film are as shown in Example 1.
This is a significant decline compared to the previous year. Further, the dispersion liquid had large coarse particles and poor storage stability. Comparative Example 3 In Example 1, initially added vinyl acetate 320g
to 384g, and 1,270g of post-added vinyl acetate to 1,
The amount was changed to 524 g, and ethylene was not added, and the process was otherwise carried out in the same manner as in Example 1. Tables 1 and 2 show the composition of the obtained dispersion and the results of physical property tests of the film. This is the case when the copolymer lacks an ethylene component, and although the strength is improved, the per-ethylene resistance and elongation are significantly reduced. Comparative example 4 Using a small capacity high pressure test container, 140g of distilled water
Add 4g of Nonipol 400, 2g of hydroxyethyl cellulose, and 32g of vinyl acetate, raise the internal temperature to 80℃, add 2g of potassium persulfate, and add ethylene pressure to 500Kg/
Polymerization was carried out for 12 hours at ^cm2 . The resulting dispersion had a solid content concentration of 32%, contained many coarse particles, and had poor storage stability. Tables 1 and 2 show the dispersion composition and the results of physical property tests of the film. This is the case when the copolymer lacks a vinyl acetate component, and both perchloren resistance and strength and elongation are significantly reduced. Comparative Example 5 The same procedure as in Example 1 was carried out except that 100 g of sodium dodecylbenzenesulfonate was used instead of hydroxyethyl cellulose and Nonipol 400. The resulting dispersion had a small particle size and contained a small amount of coarse particles. Even after settling the coarse particles, the storage stability was still poor, and the average particle size of the supernatant was 0.03μ. Table 1 shows the composition of the obtained dispersion and the results of physical property tests of the film.
and shown in Table 2. This corresponds to the average particle size being below the limit value, and compared to Example 1, the strength and elongation do not change much, but the per-cleaning resistance is considerably reduced. Example 6 The same treatment as in Example 1 was carried out except that allyl t-butyl peroxycarbonate was not used. Tables 1, 2, and 3 show the dispersion composition, physical properties of the film, and changes due to heat treatment. This is the case when the copolymer lacks allyl peroxycarbonate, and the strength and resistance to peroxidation of the film are considerably lower than in Example 1, and the effect of heat treatment is also low.

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Claims (1)

[Claims] 1. Ethylene 4.9~40.0% by weight, vinyl acetate 95.0~
A copolymer consisting of 45.0% by weight and 0.1 to 15.0% by weight of a compound represented by the following general formula (), and
Aqueous dispersion with an average particle size of 0.05 to 1.0μ. However, R ₁ is a hydrogen atom or a group selected from the group consisting of an alkyl group having 1 to 4 carbon atoms,
R ₂ and R ₃ are groups selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, and R ₄ is a group having 1 to 12 carbon atoms.
represents a group selected from the group consisting of an alkyl group or a cycloalkyl group having 8 to 12 carbon atoms.