JPS6023786B2 - Ethylene-vinyl acetate copolymer emulsion and adhesive or paint containing the emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides novel ethylene
A vinyl acetate copolymer emulsion is provided.

Ethylene-vinyl acetate copolymer emulsion (hereinafter referred to as EV
Emulsion A) is a useful emulsion that is used in a wide variety of applications such as adhesives, paints, paper processing agents, and fiber processing agents.

Particularly in the field of adhesives, in conjunction with the expansion of various plastic composite materials, we have moved from the conventional adhesion of wood or paper to each other, to the bonding of various plastics with wood or paper, and the adhesion of aluminum box laminates. Its expansion has been remarkable recently, for example, in Japanese Patent Application Laid-Open No. 53-9194.
In Publication No. 0, the total monomer amount is 10 parts, 30 to 5 parts of ethylene, and 50 to 7 parts of vinyl acetate.
．． 6-1% by weight), and a nonionic emulsifier and/or
Consisting of an EVA emulsion with an ethylene content of 30 to 5% by weight obtained by emulsion polymerization of ethylene and vinyl acetate in the presence of a dispersing agent consisting of 1 to 7 parts of an anionic emulsifier (1.6 to 14 parts by weight based on the vinyl acetate monomer). Adhesive is listed. However, upon examination by the inventors,
Although such conventional EVA emulsion adhesives have almost satisfactory performance in terms of normal adhesive strength and water resistance, it has become clear that there is room for improvement in the following points.

(2) A large amount of pigment or filler is mixed into the EVA emulsion for the purpose of improving physical properties and coating properties, as well as increasing the amount and reducing costs.

When mixing such pigments or fillers, it is essential that so-called emulsion destruction such as gelation, thickening, and aggregation does not occur, but the above-mentioned improvement effect due to the addition of pigments or fillers increases in proportion to the amount added. Therefore, it can be said that emulsions with a larger allowable amount of pigment or filler are more useful. However, in the case of conventionally known EVA emulsions, the mixing limit is at most four times as much pigment or filler as the solid content of the emulsion, and even if a larger amount of pigment or filler is added, the emulsion will not be destroyed. Or, an EVA emulsion with good filler miscibility (hereinafter simply referred to as pigment miscibility) is required. ■ Recently, high-speed adhesives have been widely used to improve productivity due to innovations in adhesive technology and adhesive machines, as seen in the case of bonding cardboard.
A-emulsion does not necessarily have sufficient initial adhesion strength, which is a requirement for such high-speed adhesion.
Improvement is desired.

■ EVA emulsion is polyvinyl alcohol (PV
It is often used in combination with water-soluble polymers such as A) and CMC, or acrylic or styrene-butadiene emulsions, but the miscibility of the two is particularly poor when mixed with the above emulsions. Therefore, if a mixed solution is left or stored for a long period of time, it may cause thickening, gelation, or phase separation, which requires careful management. In addition, there is a need to develop an EVA emulsion that has good miscibility with emulsions. However, the present inventors have conducted extensive research in order to obtain an EVA emulsion that satisfies the above requirements ① to ②.
．． Emulsion polymerization of ethylene and vinyl acetate in the presence of 5 to 2.5% by weight of anionic surfactant, 4 to 7% by weight of nonionic surfactant, and 0.2 to 1% by weight of water-soluble protective colloid. Ethylene content 20-29% by weight obtained by
The inventors have now completed the present invention by discovering novel facts such as that the EVA emulsion can satisfy all of these requirements and that such emulsion exhibits extremely useful performance as adhesives, paints, etc.

The EVA emulsion of the present invention has a solid content of 5 to 6
Even when twice as much pigment is mixed, the emulsion does not break, resulting in extremely high pigment stability.The initial adhesion strength is 3 to 6 times higher than that of conventional products, and acrylic, styrene-butadiene Because it has excellent compatibility with emulsions, CMC, PVA, etc., it has remarkable properties such as no deterioration in quality such as thickening or gelation even if the mixture is left for one month or more. a specified amount of surfactant as described above;
and EVA produced using Mizuochi-protective colloid.
Emulsions have not been known in the past, and the emulsion of the present invention is a novel emulsion that has significant characteristics in the combination of the types of drugs and the amounts used.

In the EVA emulsion of the present invention, the composition of ethylene is 20 to 2% by weight, the amount of anionic surfactant is 0.5 to 2.5% by weight (relative to vinyl acetate monomer, the same applies hereinafter), and nonionic surfactant is used. The amount of agent used is 4 to 7% by weight (
It is necessary to limit the usage amount of vinyl monomer for acetate (the same applies hereinafter) and water-soluble protective colloid to 0.2 to 1% by weight (to vinyl acetate monomer, the same applies hereinafter), and EVA outside the specified range In emulsions, it is impossible to simultaneously improve all the properties of pigment miscibility, initial adhesion, water-soluble polymer, emulsion and compatibility, and it is difficult to obtain stable emulsions, reducing practicality. .

That is, when the ethylene composition is less than 2% by weight, pigment miscibility,
Both the initial adhesive strength is reduced and the normal adhesive strength in paper/paper, paper/polyolefin adhesion, etc. is also reduced. 2$ on the other hand
If it exceeds % by weight, the internal plasticization becomes large and the tackiness increases, but the film strength decreases markedly, resulting in defects in adhesive strength due to insufficient cohesive force. The amount of anionic surfactant used is 0.
If it is less than 5% by weight, the compatibility with acrylic or styrene emulsions will be poor or coarse particles will be generated in the EVA emulsion, and if it is more than 2.5% by weight, pigment miscibility and water resistance will decrease, and both are not practical. There is a problem. If the amount of nonionic surfactant used is less than 4% by weight, the initial adhesion strength will be insufficient and pigment miscibility will be poor, and if it is more than 7% by weight, water resistance will be poor.
This becomes a problem due to insufficient adhesive strength. If the amount of the water-repellent protective colloid used is less than 0.2% by weight, coarse particles tend to form in the emulsion, resulting in a decrease in stability and poor mechanical stability such as decreased pigment miscibility and coating properties. If the amount exceeds 1% by weight, the pigment miscibility, initial adhesive strength, and miscibility with emulsions decrease.

As described above, in the present invention, it is essential to precisely specify the composition of ethylene, the amount of surfactant used, and the amount of water-soluble protective colloid used as described above, and if any one condition is outside the specified range, Even if this happens, the remarkable effects of the present invention cannot be exhibited at all.

Examples of anionic surfactants used in the present invention include alkali salts of carboxylic acids and sulfonic acids, ammonium salts such as sodium laurate or sodium stearate, sodium dodecylbenzenesulfonate, sodium vinylsulfonate, sodium laurylsulfonate, and acid phosphorus. Alkali salts of acid alkyl esters, ammonium salts such as sodium diethylhexyl phosphate, alkaline salts of acid esters of alkanols and sulfuric acid, ammonium salts such as sodium lauric sulfate, polyoxyethylene ethers and alkali dialkyl sulfosuccinates. Various salts, ammonium salts and the like can be mentioned. or,
Examples of nonionic surfactants include polyoxyethylene alkyl ether type, polyoxyethylene alkyl allyl ether type, polyoxyethylene alkyl ester type, sorbitan monoalkyl ester type, and polyoxyethylene alkyl ester type. Examples include various types such as the min type, polyoxyethylene alkylamide type, polyoxyethylene/polyoxypropylene condensation type, glyceride, and ventaeri slitester type.

Furthermore, water-soluble protective colloids include fully or partially saponified polyvinyl alcohol and its derivatives, gelatin and cellulose derivatives, maleic acid or a half-ester copolymer of maleic acid and styrene, starch, dextrin derivatives, polypynylpyrrolidone, and polyacrylic. Examples include acid amides.

Especially average degree of polymerization 400-2500, average degree of saponification 83-83
97 mol% polyvinyl alcohols are preferably used. The EVA emulsion of the present invention has, as a third component, an unsaturated vinyl monomer having a glycidyl group such as glycidyl acrylate or glycidyl methacrylate, a methylol compound such as N-methylolacrylamide or N-methylolmethacrylamide, and its methyl or ethyl compound. , unsaturated vinyl monomers having an N-methylol group or alkoxyl group such as alkyl ethers of butyl ether, unsaturated vinyl monomers having a carboxyl group or carboxylic acid ester group such as acrylic acid, itaconic acid, maleic acid and their esters, etc. It is also possible to contain a small amount of.

To prepare the emulsion of the present invention, a surfactant, a water-soluble protective colloid, a state buffer, water, a catalyst, and vinyl acetate monomer (a predetermined amount of 10-100%
%) and emulsify it.

Next, after pressurizing nitrogen gas and replacing the inside of the autoclave,
Inject ethylene under pressure. Polymerization is initiated by heating, and the remaining vinyl acetate monomer (0 to 90% of the predetermined amount) and, if necessary, a further catalyst are added in batches, in portions, or all at once to continue polymerization. The injection of ethylene may be carried out all at once, in parts, or continuously. The EVA emulsion thus obtained can be used for various purposes as it is, or after being diluted or concentrated as appropriate, and with the addition of a thickener or the like.

EVA emulsion can of course be used alone, but
Depending on the purpose, homopolymer emulsions and copolymers of water-repellent polymers such as polyvinyl alcohol and its derivatives methyl cellulose, ethyl cellulose, and carboxymethyl cellulose, or acrylic monomers such as acrylic acid or methacrylic acid and their alkyl esters. It can be used by mixing with various emulsions such as coalescent emulsion and styrene-butadiene emulsion.

When used as an adhesive, auxiliary agents such as clay, kaolin, extender pigments such as silica, fillers, crosslinking agents, and waterproofing agents are mixed as appropriate. There are no particular restrictions on the objects of adhesion, including adhesion of various products such as wood products, paper products, cloth products, plastics, etc. or a combination of these products, and lamination adhesion of metal foil such as aluminum foil and paper or plastic film. Alternatively, it can be used for any adhesive application such as flocking, non-woven fabric production, fiber bonding in carpet back coating, etc.

When used as a coating material, in addition to various pigments, arbitrary coating aids such as volatile film forming aids, antifreeze agents, plasticizers, dispersants, antifoaming agents, and antifungal agents may be blended.

The paint can be applied to any material, both internally and externally. Next, an example will be given and the E of the present invention will be explained.
VA emulsion will be explained in more detail.

Examples 1 to 3, Control Examples 1 to 8 A water-soluble protective colloid, a nonionic surfactant, and an anionic surfactant were added to a stainless steel autoclave equipped with a magnetic frame breaker in the amounts shown in Table 1 as a pH buffer. (Dibasic sodium phosphate/decahydrate) 1. 10 parts of pure water, 0.15 parts of Rongalit and 2 parts of vinyl acetate monomer
Akatsukibe was prepared to make an emulsion.

After purging with nitrogen, salt elevation and ethylene injection were carried out, and two doses of a 1% solution of a catalyst (ammonium persulfate) were added to initiate polymerization. While maintaining the ethylene pressure at 50 k9/kg, the remaining 8 parts of vinyl acetate monomer and the catalyst were continuously charged and polymerized for 5 hours.

After the charging of the pinyl acetate monomer was completed, the injection of ethylene was stopped, and 1. Insect time, polymerization was built. Table 1 shows each performance of the obtained EVA emulsion.

In Table 1, the contents of surfactants and water-soluble protective colloids are shown on a weight basis with respect to vinyl acetate.

The conditions in parentheses in the control example are outside the scope of the present application. In addition, the following symbols were used. D Shigeru: Sodium dodecylbenzenesulfonate RSN: Sodium lauryl sulfonate PON; Polyoxyethylene nonyl phenyl ether (HLB15-19) E○/PO; Polyoxyethylene polyoxypropylene block polymer (oxyethylene content 40-60 %, oxypropylene average molecular weight 1
200-2000) PVA: Polyvinyl alcohol (average degree of saponification 87-89 mol%, degree of polymerization 1400) Momofune note) Performance evaluation was performed using the following test method.

Pigment miscibility: 10 minutes of EVA emulsion adjusted to a solid content concentration of 47% was separated into a glass spindle, carbonated with a glass birch until it became difficult to pour, and mixed with Wheaton B. When mixing Shiroishi Calcium (manufactured by Shiroishi Calcium ■), measure the weight times the carbonate ratio per 8VA unit solid content. Initial adhesive strength: 12
Apply 8 VA Emulsion to 12 x 12 x 100 ml of kraft paper at a rate of 17 g/day in terms of solid content. Press another piece of kraft paper onto this.

Next, the minimum time required to obtain a paper coverage of 50% is measured. 20℃. Measured at 65%RH) Emulsion shelf sheath:
■Ear VA emulsion and acrylic emulsion lo
o0ocps) at a rate of 1 L weight) for 10 minutes. Immediately after manufacturing. The viscosity after 10 days was measured at 25°C using a BH type viscometer or a BL type viscometer. (enter in the top row of Table 1)
■Measurements were made in the same manner as in ■, except that SBR latex (100 cps) was used instead of the acrylic emulsion.
(Entered in the lower row of Table 1) Normal adhesive strength: EVA emulsion was applied on a soft polyvinyl chloride film at a rate of 24 g/ml (solid content), and high-quality paper was attached. 20℃, 65
After curing at RH for 24 hours, peel off by hand or using an autograph.

Paper coverage of 80% or more ◎. 80-40% 〇. 40-10
△. Scores of 10 or less are marked/indicated with an x.

Water resistance: A sample obtained by the same method as the sample used to measure the initial adhesive strength was cured for 48 hours at 20°C and 65% RH, and then soaked in water at 20°C for 24 hours.

The adhesive surface was then peeled off by hand and evaluated using the same criteria as normal adhesive strength. Examples 4-6 EVA emulsions as shown in Table 2 were prepared according to Example 1.

Claims (1)

[Claims] 1. 0.5 to 2.5% by weight of anionic surfactant, 4 to 7% by weight of nonionic surfactant, and 0.2 to 1% by weight of water-soluble based on vinyl acetate. An ethylene-vinyl acetate copolymer emulsion having an ethylene content of 20 to 29% by weight, obtained by emulsion polymerization of ethylene and vinyl acetate in the presence of a protective colloid. 2 In the presence of 0.5 to 2.5% by weight of an anionic surfactant, 4 to 7% by weight of a nonionic surfactant, and 0.2 to 1% by weight of a water-soluble protective colloid based on vinyl acetate. An adhesive comprising an ethylene-vinyl acetate copolymer emulsion with an ethylene content of 20 to 29% by weight obtained by emulsion polymerization of ethylene and vinyl acetate. 3 In the presence of 0.5 to 2.5% by weight of an anionic surfactant, 4 to 7% by weight of a nonionic surfactant and 0.2 to 1% by weight of a water-soluble protective colloid based on vinyl acetate. A paint containing an ethylene-vinyl acetate copolymer emulsion with an ethylene content of 20 to 29% by weight obtained by emulsion polymerization of ethylene and vinyl acetate.