JPS6031349B2 - water-based adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new vinyl acetate copolymer emulsion type water-based adhesive, and the adhesive of the present invention has excellent initial adhesion and low-temperature adhesion, and is suitable for high-speed mechanical adhesion. It has quick drying properties.

Conventionally, polyvinyl acetate emulsion type adhesives have been widely used as adhesives for paper and fiber substrates, and they have the advantages of being inexpensive, easy to use, and having excellent adhesive strength under normal conditions. ing.

On the other hand, it has the disadvantages of poor water resistance, relatively slow adhesion speed, poor workability, and limited usage. In addition, various plastic film surfaces including polyvinyl chloride film, corrugated paper surfaces with water repellent treatment, vinylon, natron, acrylic, polypropylene,
Fiber materials mainly made of synthetic fibers such as polyester have poor adhesion, making them unsuitable for practical use. On the other hand, the solvent used in organic solvent solution adhesives is expensive, and there is a strong demand for replacing them with water-based adhesives from the standpoint of environmental health and safety. Expansion of the scope of application is desirable.

Therefore, this is the first time for polyvinyl acetate emulsion type adhesives, which are the most widely used water-based adhesives. It would be extremely beneficial to improve early adhesion, especially low temperature adhesion, and provide spin drying properties. However, the adhesion suitability of an adhesive is determined by a combination of various factors, and the effect is expressed comprehensively, and it is difficult to improve the adhesion by focusing on only some of the factors.
Here, the present inventors have improved polyvinyl acetate emulsion from various aspects, and as a result, have completed the water-based adhesive of the present invention.

That is, according to the present invention, ``When performing seed polymerization using an aqueous dispersion of a pinyl polymer as a seed, an ethylene-vinyl acetate copolymer having an ethylene content of 10 to 55% by weight is used as the vinyl polymer as a seed. Monomer to be polymerized 100
Using 5 to 4 parts by weight in terms of solid content per part by weight, using polyvinyl alcohol with a number average molecular weight of 400 to 2,000 and an average degree of quesoization of 90 to 98% as a protective colloid, and per 100 parts by weight of vinyl acetate and vinyl acetate. Seed polymerization is carried out by continuously or intermittently adding 0 to 40 parts by weight of another pinyl polymerizable monomer to the polymerization phase, and the melt viscosity (at 17000) of the resulting polymer is 1. .0×
An aqueous adhesive having excellent quick-drying properties and low-temperature adhesion properties comprising an aqueous dispersion of a vinyl acetate polymer having a particle size of 1 to 8.0×1 pipoise is provided.

Ethylene content used here as seeds 10-5
A 5% by weight aqueous dispersion of ethylene-warped vinyl acetate copolymer usually has a solid content of 30 to 55% by weight, and is available as a commercial product or can be easily produced by a commonly used emulsion polymerization method. I can do it.

For example, Special Publication No. 38-8988, Special Publication No. 47-3732
Although the copolymer used in the present invention can be produced by the production method described in the specification of Japanese Patent No. 808298, the K-value of the coefficient of polymerization degree is particularly 70. The above is preferable. In such an aqueous ethylene-vinyl acetate copolymer dispersion, if the ethylene content is less than 10% by weight, the resulting adhesive will have poor low-temperature adhesion and poor adhesion to hydrophobic substrates. It's inappropriate.

On the other hand, if the ethylene content exceeds 55% by weight, it is difficult to stably produce an aqueous dispersion using the usual emulsion polymerization method, and the long reaction time under high pressure is required, which increases costs. Not desirable.

In addition, the particle diameter of the dispersed copolymer in the aqueous dispersion is 0.2
A particle size in the range of ~3 microns is preferred; a particle size less than 0.2 microns is unsuitable because the resulting adhesive will have poor spin-drying properties. On the other hand, when an aqueous dispersion with a particle size exceeding 3 microns is used, it contains a large amount of aggregates or the mechanical stability decreases in the emulsion polymerization (seed polymerization) process.
It has the disadvantage that it is difficult to obtain an adhesive with satisfactory stability. On the other hand, the polyvinyl alcohol used as the protective colloid has a number average molecular weight of 400 to 2000 and an average degree of saponification of 90 to 98%.

Polyvinyl alcohol with an average saponification degree of 90 to 98% is
It can be produced by blending fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol in appropriate proportions. Further, the use of a nonionic or anionic surfactant may be considered within a range that does not impair the advantages of the adhesive of the present invention. Such polyvinyl alcohol is used in an amount of 1.5 to 15 parts by weight per 10 parts by weight of monomers to be seed polymerized.

The polymerization phase (polymerization medium) of the seed polymerization is the ethylene-vinyl acetate and polyvinyl alcohol in an amount of fresh water such that their total solid content is 5 to 55 parts by weight per 100 parts by weight of fresh water. It is adjusted by blending with.

Then, vinyl acetate alone or a mixture of vinyl acetate and other vinyl-polymerizable monomers in an amount of not more than 4 parts by weight per 10 parts by weight of vinyl acetate is added to the polymerization phase, and the emulsification weight is determined.

Here, examples of other vinyl copolymerizable monomers include carboxylic acid vinyl esters other than vinyl acetate, such as vinyl formate, vinyl propionate, and vinyl versatate, and alcohol residues having 1 to 8 carbon atoms (meth )
Acrylic acid esters are preferred, and other examples include ethacrylic acid esters, dicarboxylic acid esters or monoesters such as itaconic acid, maleic acid, and fumaric acid, and halogenated unsaturated hydrocarbons such as vinyl chloride and vinylidene chloride. can.

As a method for injecting the monomer into the polymerization phase, a method generally used in emulsion polymerization can be adopted.

For example, a method in which a part of the monomer components is charged into a reaction vessel in advance or not at all, and the remaining or all monomers are continuously added dropwise at the reaction temperature to complete the polymerization; A method in which the polymerization is completed by intermittently injecting the components or by dividing them into two or several times, and when injecting the components in two or more times, the temperature of the polymerization phase is lowered to below the reaction temperature, and the monomer content is There is a method in which polymerization is completed by injecting the polymer and then raising the temperature to the reaction temperature again. The reaction temperature is generally 70 to 80 qo, which is often used when vinyl acetate is polymerized by emulsion polymerization.

As the initiator used as the polymerization catalyst, any catalyst generally used in emulsion polymerization can be used.

Various free radical forming catalysts may be used, such as peroxides. Particularly commonly used initiators are ammonium persulfate,
Potassium persulfate, sodium persulfate and similar salts of perchloric acid, hydrogen peroxide. Furthermore, organic peroxides such as penzoyl peroxide, lauroyl peroxide, t
-Butyl hydroperoxide etc. can also be used. The appropriate amount of the initiator used is 0.05 to 2 parts by weight per 10 parts by weight of the monomer.

It is also possible to use reducing agents and activators in combination with these oxidizing agents; suitable examples include compounds with reducing properties such as bisulfites, sulfoxylates or ferrous salts. . The amount of these reducing agents and activators used is preferably 25 to 100 parts by weight per 100 parts by weight of the initiator. The major drawbacks of water-based adhesives under relatively low temperature conditions are that the evaporation temperature of water is slow and the formation of a continuous film between polymer particles is insufficient, resulting in lack of quick softening and poor initial adhesive strength.

The purpose of the present invention is to simultaneously solve the problems of drying properties and film forming properties at relatively low temperatures, and for this purpose, it has been found that the fluidity of polymers has an important relationship. That is, the melt viscosity at 170 oo of the dispersed polymer in the vinyl acetate copolymer aqueous dispersion obtained by seed polymerization is 1.0 x 1 pipoise to 8.0 x 1 pipoise, preferably 1
．． It must be between 2×1 pipoise and 7.8×1 pipoise.

When the melt viscosity value is less than 1.0×1, the adhesive strength is poor when used as an adhesion agent, and sufficient cohesive adhesive strength is not exhibited.

If the value exceeds 8.0×1 pi, the film forming property at 5 to 0° C. will be reduced, and the ability to form a uniform continuous film will be significantly inhibited, resulting in failure to obtain sufficient adhesive strength. The melt viscosity is
It is determined by evaporating water from an aqueous dispersion at 23° C. and 65% RH to form a film, and measuring this film at 170 qC using a Koka type flow tester.

To prepare adhesives from aqueous dispersions, various additives commonly used in aqueous saddle adhesives are added.

For example, water-soluble solvents commonly used as film-forming aids,
It is preferred to add water-insoluble solvents and plasticizers, the amount used being 0 to 4 parts by weight, preferably 5 to 30 parts by weight per 10 parts by weight of polymer solids. Other commonly used inorganic fillers such as rutile titanium oxide, calcium carbonate, clay, and crystalline silica powder, and water-dispersible organic pigments may also be added. For adjusting the pH and viscosity of the adhesive, aqueous ammonia diluted or dissolved with water, sodium bicarbonate, sodium and potassium polyphosphate, sodium and potassium hexametaphosphate, etc. can be used.

The thus obtained adhesive of the present invention is applied to a substrate by coating methods generally used for water-based adhesives, such as roll coating, knife coating, spray coating, and dipping coating.

The adhesive of the present invention has excellent storage stability, centrifugal properties, low-temperature (below 5°C) adhesion, especially initial adhesion, and water-resistant adhesion, and is also excellent in high-speed mechanical compatibility due to its low thixotropy. Adhesive for folder glue for pasting cardboard boxes, adhesive for pasting paper, adhesive for bag making, adhesive for paper tubes, adhesive for packing processing of pile fabrics, needle punched carpets, etc., polyvinyl chloride film. and kraft paper, adhesives for polyester film and kraft paper, adhesives for adhesion and coating of polypropylene, vinylon fibers, and other compound woven and knitted materials, and the adhesive of the present invention encompasses these uses. .

Next, the present invention will be specifically explained with reference to Examples, but it goes without saying that the scope of the present invention is not limited thereby.

"Parts" in the examples are based on weight. Example 1 7 parts of ion-exchanged water, Gohsenol AH-17 (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., polyvinyl alcohol with an average saponification degree of 98%) > 4.5 parts, Gohsenol GL-05 (manufactured by Nippon Gohsen Kagaku Kogyo Co., Ltd.) , polyvinyl alcohol with an average degree of saponification of 88%) was placed in two or five low flasks and overflowed to 80°C to completely dissolve the contents, and then cooled to 30°C.

Next, Evadic EP-11-L (manufactured by Dainippon Ink and Chemicals Co., Ltd., ethylene content 22% by weight, K value 140
2 $ of ethylene-vinyl acetate emulsion) was charged, 1 part of vinyl acetate was injected, and the air in the reaction vessel was completely replaced with nitrogen gas. Then 0.2 bicarbonate of soda
An aqueous solution prepared by dissolving 5 parts of potassium persulfate in 2 parts of ion-exchanged water was added, and an aqueous solution of 0.04 parts of potassium persulfate dissolved in 3 parts of ion-exchanged water was added, and the temperature was raised to 8,000 ℃ while worshiping the contents. 8,000 and held for one flow, and when the heat generation subsided, the remaining 9 parts of vinyl acetate and 0.36 parts of potassium persulfate were added.
An aqueous solution prepared by dissolving 1 part in 5 parts of ion-exchanged water was added dropwise over a period of about 3 hours.

After that, the polymerization was completed by aging for about 1 hour at 8,000 ℃.
After cooling to 0.00, 2 parts of dibutyl phthalate and 2 parts of ion-exchanged water were added dropwise and dispersed over 30 minutes.
It was cooled to below 0 and taken out through a 100 mesh oven cloth. Table 1 shows the physical properties of the obtained dispersion A-1.
Example 2 Dispersion A-2 was obtained in the same manner as in Example 1, except that Evadic EP-11-L was changed from 2 to 4 anchor parts.

Its physical properties are shown in Table-1. Example 3 7 parts of ion-exchanged water, 5 parts of Gohsenol AH-17, and 0 parts of Gohsenol GH-17 (manufactured by Nippon Gohsen Kagaku Kogyo Co., Ltd., borivinyl alcohol with an average degree of saponification of 88%)
．． 2 parts 2 parts 5 were placed in a low flask and overflowed to 8,000 ml to completely dissolve the contents, and then cooled to 3,000 ml.

Next, 25 parts of Evadic EP-11-L were charged, the air in the reaction vessel was completely replaced with nitrogen gas, and an aqueous solution of 0.25 parts of sodium bicarbonate dissolved in 2 parts of ion-exchanged water was added to make the contents cloudy. The temperature rose to 8,000 while praying. An aqueous solution prepared by diluting 10 parts of vinyl acetate and 0.5 part of 35% hydrogen peroxide solution in 8 parts of ion-exchanged water was added dropwise over a period of about 3 hours.

After that, it was aged for about 1 hour at 8,000 ℃ to complete the polymerization.
Table 1 shows the physical properties of dispersion A-3 obtained by cooling to 0.00 and adjusting in the same manner as in Example 1. Example 4 7 parts of ion-exchanged water, 5 parts of Gohsenol AH-17, 0.2 parts of Gohsenol GH-17, and 0.3 parts of Gohsenol GL-05 were placed in a low flask and added to 8000. After completely dissolving the overflowing contents, 3.
Cooled to 0o0.

Next, two units of Evadic EP-11-L were charged, one unit of vinyl acetate was injected, and the air in the reaction vessel was completely replaced with nitrogen gas. Next, an aqueous solution of 0.25 parts of heavy carbon soda dissolved in 2 parts of ion-exchanged water was added to give a concentration of 35%.
An aqueous solution prepared by diluting 0.05 parts of hydrogen oxide water with 3 parts of ion-exchanged water was added, and the contents were heated to 80 qo while stirring. Hold at 8,000 for 1 minute and when the heat generation subsides, add the remaining monomer solution of 8 parts of vinyl acetate and 1 part of 2-ethylhexyl acrylate and 0.45 part of 35% hydrogen peroxide solution to ion-exchanged water. An aqueous solution diluted to 5 parts was added dropwise over about 3 hours.

After that, the polymerization was completed by aging at 80 qo for about 1 hour, and then the mixture was cooled to 40° C., and then 1 part of dibutyl phthalate and 2 parts of ion-exchanged water were added dropwise and dispersed over 30 minutes, and the temperature was lowered to below 30°C. Cool and pass through a 100 mesh oven cloth. Table 1 shows the physical properties of the obtained dispersion A-4. Comparative Example 1 9 parts of ion-exchanged water and 0.0 parts of Gohsenol AH-17.
5 parts, 3 parts of Gohsenol GH-17, Gohsenol G
Take 1.5 parts of L-05, put it in a 5-necked 2-k flask, and add 8000 ml of water to completely melt the contents.
000.

Next, one portion of vinyl acetate was injected to completely replace the air in the reaction vessel with nitrogen gas. After that, the same operation as in Synthesis Example 1 was carried out to complete the polymerization. At 4,000 ℃, dibutyl phthalate (3) and ion exchange water (3) were added dropwise and dispersed, and after cooling to below 30q0, it was placed in a 100 mesh furnace. I passed the cloth through it and took it out. Obtained dispersion B
In order to compare Sample-1 with Examples, its physical properties are also listed in Table-1. Comparative Example 2 All operations were performed in the same manner as in Comparative Example 1 except that Gohsenol GH-17 was changed from 3 parts to 1.5 parts and Gohsenol GL-05 was changed from 1.5 parts to 3.0 parts. The physical properties of the obtained dispersion B-2 are shown in Table 1 for comparison with Examples.
Also listed in

[Method for measuring physical properties of aqueous polymer dispersion]

'1} Thixo coefficient The slope of the viscosity per rotational speed on paper using a BM type viscometer [
2- Minimum film-forming temperature of aqueous dispersion: by temperature gradient heating plate L-type minimum film-forming temperature measuring device.

[3' Film hardness: Apply the aqueous dispersion to a glass plate of 7 x 10 arcs with a 3 mil applicator and obtain a hardness of 23±100, 65% R. Day. After drying for 2 hours, the resulting film was dried for 2 hours. A film with a film thickness of 0.6 for tensile strength and elongation measured using a rocker hardness tester was prepared, and a specimen was prepared using a No. 2 dumbbell to measure 23±100, 65% R. Day. And tenshi.

Measured using UTM-4 at a tensile speed of 20 m/min.
5} Film Water Resistance [The film specimen on the glass plate obtained in 21 was immersed in water at 23° C. for 24 hours, and then the condition of the film was observed.

'6} Film drying time to touch of aqueous dispersion The aqueous dispersion was applied to a glass plate of 7 skins x 10 cm with a 1.5 mil applicator, and 'a-23q0, 65% R. Day. as well as'
b-400, 45%R. Day. The time (seconds) until the adhesiveness of the coating film disappeared was measured under these conditions.

Table 1 Example 5 The dispersions prepared in Examples 1 and 3 were applied to kraft paper.
It is applied using a 5 mil applicator, and a rubber roller with kraft paper layered thereon is pressed back and forth to adhere.

Table 2 shows the initial adhesion (indicated by paper breakage rate) when the kraft paper adhered for a predetermined period of time is peeled off, in comparison with the dispersions of Comparative Examples 1 and 2. Table 2 (Unit is paper tear rate) Paper tear rate (%) = Kaoru Seiun Kaoru X. .

. Example 6 The aqueous dispersion A-2 of Example 2 was used to bond a rayon fabric used as a wrapping material to processed paper that had been flameproofed by resin impregnation.

Bar coater No. to flame-retardant paper. After applying A-2 using a No. 32 coating rod (coating amount: wet 64/min), layer the rayon fabric and stick it together by reciprocating with a hand roller, and dry with soaked hot air circulation at 10,000 for 1 minute. Heat treatment was performed in the machine.

Cut out 25 sides x 15 ribs of the glued wall covering material, peel off one end by 50 mm, fix the peeled rayon fabric with a clip and hang it, and attach 100 mm to one end of the peeled processed paper. Table 3 shows the peeled length when the weight was hung and the sample was allowed to stand still for 3 minutes, in comparison with B-2 of Comparative Example 2. Table-3 1 23±1℃, 65%R. Day. Measured at 2 23±1
℃ water was applied with a brush to the surface of the rayon woven fabric by approximately 0.5 taps, and after 10 seconds, the temperature was 23±100, 65% R. Day. Measured indoors.

Example 7 The aqueous dispersion A-4 of Example 4 was used to bond a foamed PVC sheet (for cushion floor use) and a nonwoven fabric (polyester yarn = 70/30).

Foamed PVC Sheet Heber Coater No. After applying A-4 using a No. 40 coating rod (coating amount: wet 48 min./final), the nonwoven fabric webs were stacked and pressed together with a hand roller in one reciprocating motion, and soaked with hot air circulation at 8,000 rpm for 10 minutes. After pre-drying in a dryer, 1
Press bonding was carried out under the conditions of 40qo x 4k9' x low ec. For comparison, adhesive processing was performed in the same manner using Comparative Example 1 B-1 as an adhesive. 23±1℃, 65%
R. Day. When peeled off after being left in a room for 2 hours, it was found that the adhesive strength of the processed base material bonded using A-4 was strong enough to cause destruction of the nonwoven fabric, but that of the processed base material bonded using B-1. The adhesive layer is easily peeled off from the surface of the foamed PVC, making it unusable as a base material for cushion floors.

Claims (1)

[Claims] 1 When carrying out seed polymerization using an aqueous vinyl polymer dispersion as a seed, an ethylene-vinyl acetate copolymer having an ethylene content of 10 to 55% by weight is used as the vinyl polymer, and 100% of the monomer to be seed polymerized is used. Use 5 to 40 parts by weight in terms of solid content per part by weight, use polyvinyl alcohol with a number average molecular weight of 400 to 2000 and an average saponification degree of 90 to 98% as a protective colloid, and use vinyl acetate and 0 per 100 parts by weight of vinyl acetate. Seed polymerization is carried out by continuously or intermittently adding ~40 parts by weight of other vinyl polymerizable monomers to the polymerization phase, so that the melt viscosity (at 170°C) of the resulting polymer is 1. .0×10^3~8.0×10
A water-based adhesive with excellent quick-drying and low-temperature adhesion properties consisting of an aqueous dispersion of a vinyl acetate polymer with ^4 poise.