JPS6119678A - Aqueous dispersion of ethylene/vinyl acetate copolymer resin - Google Patents

Abstract

PURPOSE:To provide the titled dispersion which lowers the lowest film-forming temp. and gives a coating film having excellent adhesion, cohesive force and flexibility, by dispersing an ethylene/vinyl acetate copolymer resin in an aq. medium by using a combination of a surfactant and protective colloid. CONSTITUTION:An ethylene/vinyl acetate copolymer resin (A) having a vinyl acetate content of 10-40wt% and an MI of 0.1-400, 2-30wt% soap (B) of wood rosin dimer composed of 90% resin acid obtd. from a root of an aged pine tree and 10% non-oxidizing material as a surfactant and a resin (C) as protective colloid obtd. by neutralizing 5-80wt% ethylene/(meth)acrylic acid copolymer composed of 98-10wt% ethylene and 2-90wt% (meth)acrylic acid, are dissolved in a solvent mixture of a water-immiscible solvent and a polar solvent and vigorously stirred in an aq. medium at a temp. which is lower by 10-20 deg.C than the azeotropic temp. of said solvent/water azeotrope for 5-30min. Said solvent mixture is then evaporated under vacuum to obtain the titled dispersion having a solid content of 40wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention can provide coating films with excellent properties such as adhesive strength, cohesive force, and flexibility, and has a relatively low minimum film forming temperature, and has a vinyl acetate content of 10 to 10%. 40 fk-ethylene
The object of the present invention is to provide a stable aqueous dispersion of a vinyl acetate copolymer resin, particularly a stable aqueous dispersion of an ultrahigh molecular weight ethylene-vinyl acetate copolymer resin having a melt index of 2 or less.

(Industrial Application Field) The ethylene-vinyl acetate copolymer resin aqueous dispersion of the present invention can be widely used in various applications, and can be particularly advantageously used in the field of heat-sensitive adhesives. It can also be used as a coating agent or processing agent for fibers, paper, etc., and can also be used as a modifier for various latexes and synthetic resin emulsions.

(Prior Art) Ethylene-vinyl acetate copolymer resins, especially ethylene-vinyl acetate copolymer resins having a relatively low vinyl acetate content of 1.0 to 40% as obtained by bulk polymerization. Vinyl acetate copolymer resin is widely used as an excellent hot-melt adhesive (heat-sensitive adhesive or hot-melt adhesive) in fields such as bookbinding, packaging, woodworking, plywood, lamination, and shoemaking. However, since it has excellent heat-sealability and barrier properties, it is widely used as a hot-melt adhesive, a coating agent, a processing agent, etc. in the fields of paper and textiles.

However, when using such ethylene-vinyl acetate copolymer resins with low vinyl acetate content as adhesives, coating agents, fiber processing agents, etc., if they are dissolved in a solvent and made into a solvent type, they can cause fire hazards. There is a risk of pollution and deterioration of the working environment, and if a melt coating type is used, the coating process is troublesome, so it is preferable to use it as an aqueous dispersion.

Conventionally, aqueous dispersions of ethylene-vinyl acetate copolymer resins manufactured by emulsion polymerization have been used for a long time and have been supplied to the market, but ethylene-vinyl acetate obtained by emulsion polymerization Copolymer resins have a significantly high vinyl acetate content (for example, vinyl acetate content t70-95 qb), have poor heat sealing properties, and have insufficient adhesion performance to plasti and kufilms such as polyzolopyrene films and ethylene terephthalate films. There wasn't.

It is also already known that the ethylene vinyl acetate copolymer resin with a low vinyl acetate content can be dispersed in an aqueous medium using a surfactant, such as by a solvent method or an autoclave method. It has already been proposed to use dimeric soaps such as sodium, potassium and ammonium salts as surfactants (Japanese Patent Publication No. 35145/1983). However, when such a surfactant is used to disperse an ethylene-vinyl acetate copolymer resin with a low vinyl acetate content in an aqueous medium, especially when a high molecular weight ethylene-vinyl acetate copolymer is dispersed, It has poor stability, and if a large amount of surfactant is used to improve stability, it has the disadvantage that the adhesive strength, cohesive force, water resistance, etc. of the dried coating film deteriorates.9.
Furthermore, in order to improve the drawbacks of dispersions using such surfactants, an acrylic resin having neutralized Cal and Φ sil groups is used as a protective colloid to disperse an ethylene-vinyl acetate copolymer resin in an aqueous medium. It has already been proposed to disperse the
5438). However, if you try to disperse ethylene-vinyl acetate copolymer resin using a 75-island protective core air agent, especially when trying to disperse a high molecular weight one, you will need to use a surfactant to disperse it. A significantly larger amount of protective colloid is required than the amount of surfactant used in the case where the amount of protective colloid is increased.

Moreover, the dispersion using such a large amount of protective colloid agent will result in a coating film with properties such as excellent adhesion, heat sealability, and flexibility that should be characteristic of ethylene-vinyl acetate copolymer. This results in serious disadvantages in that the minimum amount of film formation required when coating on a substrate or the like and drying becomes high.

By the way, if the minimum film-forming temperature becomes higher, a higher drying temperature of 80 to 100°C is required to form a continuous drying film, and that high drying temperature is required for a certain period of time to form a transparent film. It is necessary to hold it, and the coating film forming operation is troublesome and work efficiency is significantly reduced, and a large amount of energy is required.

In particular, ethylene-vinyl acetate copolymer resins with a melt index (hereinafter referred to as "MI") of 2 or less and an ultrahigh molecular weight of 1, which have been synthesized in recent years, have remarkable properties such as cohesive strength and toughness. Because of its excellent properties, it is ideal for adhesives and coatings that require such performance. However, such ultra-high molecular weight ethylene-vinyl acetate copolymer resin has a high melt viscosity, and in order to use it as a hot melt adhesive, it is necessary to reduce the melt viscosity by adding wax etc. If added, it is inevitable that performance such as chemical resistance, which is a special feature, will deteriorate.

In addition, in order to make such ultra-high molecular weight ethylene-vinyl acetate copolymer resin into a stable aqueous dispersion, it is necessary to use large amounts of the above-mentioned surfactants and protective colloids. Properties such as adhesion, cohesive force, water resistance, heat sealability, and flexibility of the coating film inevitably deteriorate, and furthermore, the minimum film forming temperature increases.

(Problems to be Solved by the Invention) The invention is based on an aqueous dispersion of an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 10 to 40% by weight, particularly an ultra-high molecular weight resin with an MI of 2 or less. It has excellent dispersion stability, and the dry heavy film has excellent properties such as adhesion, cohesion, water resistance, heat sealability, and flexibility, and the minimum film forming temperature is not too high. The purpose is to provide a dispersion.

(Means for Solving Problems) The above object of the present invention is to use a dimeric surfactant as a surfactant.
Ethylene-vinyl acetate copolymer resin with a low vinyl acetate content is prepared in an aqueous medium by using Drozin soap together with neutralized ethylene-(meth)acrylic acid copolymer resin as a protective colloid agent. This could be achieved by dispersing it into

That is, the ethylene-vinyl acetate copolymer resin dispersion of the present invention is produced by dispersing an ethylene/vinyl acetate copolymer resin having a vinyl acetate content of 10 to 40% by weight in a dimeric form and a soap solution. It is made by dispersing it in an aqueous medium in combination with a hydrated ethylene-(meth)acrylic acid copolymer resin.

The ethylene-vinyl acetate copolymer resin in the present invention is
Vinyl acetate content is 10-40% by weight, preferably 1
0 to 35''Rt%, preferably 20 to 30% by weight.If the vinyl acetate content is too low, the adhesiveness and hot tack properties of this copolymer resin will decrease;
The flexibility of the coating film deteriorates. Furthermore, if the vinyl acetate content is too high, physical properties such as water resistance and chemical resistance will deteriorate, and the sealing and kingability will increase.

The molecular weight (M) of this copolymer resin is selected depending on the application of the aqueous dispersion, etc., but ultra-high molecular weight resins with MI of 2 or less have excellent properties such as cohesive force and toughness. Such a copolymer resin may be a copolymer of only ethylene and vinyl acetate, or may be a copolymer of ethylene and vinyl acetate with other polymers. There is no problem even if the part of the copolymer is a water decomposition product. Examples of other monomers to be copolymerized include acrylic acid, me-nucleic acid, and 711ic acid anhydride. The copolymerization ratio is usually S
tf chi or less.

In the present invention, dimeric urape is used as a surfactant.
Igin soap is used. Examples of the opening soap include soaps such as sodium, potassium, ammonium, and organic attenuated soaps, with sodium, potassium, and ammonium soaps being particularly preferred, and a combination of sodium or potassium soap and ammonium soap being more preferred.・Dimeric soap, Dorosif soap, is made up of about 90% resin acid obtained from the roots of old pine trees and about 10% compensating substances.
I<Dear Op Technology” (Interscience Encyclopedia (published by Deere Inc.), Volume 11, No. 779
It is described on pages 810 to 810 of both books. This dimeric compound, drosin, can be found in old sources, for example, Dymare, Cus, manufactured by S-Cures Chemical Co., Ltd.
It is commercially available under trade names such as m@r@x) J. Such commercially available products can be used as desired in wood inventions.

In the case of Mokujyomei, it is possible to use drosin in the form of soap such as sodium soap, potassium soap, and barium soap in advance. During the preparation of the dispersion, for example, by mixing dimeric wood rosin previously dissolved in a solvent with an aqueous medium containing sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate or ammonia, etc. You can change the soap ff1K on the spot. The amount of the dimeric soap used is usually 2 to 30 parts by weight, preferably 5 to 2 parts by weight, based on the ethylene-vinyl acetate copolymer resin.
It weighs 0. If the amount of opening is too large, a stable dispersion can be obtained, but the adhesion, cohesive force, water resistance, etc. of the dried coating will be reduced, and if it is too small, a stable dispersion cannot be obtained.

In the present invention, a neutralized ethylene-(meth)acrylic acid copolymer resin is used as a Hoya colloid agent in combination with the dimeric 1077 soap. Copolymer resin is a copolymer resin of ethylene and acrylic acid and/or methacrylic acid.
The copolymerization ratio of acrylic acid and methacrylic acid is 2 to 90 weights, preferably 5 to 20 weights, based on the resin. In addition, the use of neutralized ethylene-(meth)acrylic acid copolymer resin is usually 5 to 80% by weight, preferably 10% by weight of the resin before neutralization, based on the ethylene-vinyl acetate copolymer resin. ~
It is 50% by weight. If the amount of the adhesive colloidal resin used is too large, the adhesion, heat sealability, flexibility, etc. of the coating film will deteriorate, and the minimum film forming temperature will become high. Moreover, if the amount used is too small, the stability of the dispersion will deteriorate.

Although the neutralized ethylene-(meth)acrylic acid copolymer resin in the present invention can be added in the form of a neutralized resin, it is usually added in the above-mentioned dimeric wood-a-gin soap. As in the case of , neutralized resin is produced by neutralizing the free resin with an alkaline agent during the preparation process of the dispersion of the present invention.

The aqueous ethylene-vinyl acetate copolymer resin dispersion of the present invention can be used in various embodiments. However, the typical preparation method is as follows.

First, an ethylene-vinyl acetate copolymer resin, a dimeric wood rosin, and an ethylene-(meth)acrylic acid copolymer resin are dissolved in a mixed solvent of a water-immiscible solvent and a polar organic solvent.

The water-immiscible solvents include, for example, hydrocarbons such as benzene, toluene, xylene, and cyclohexane; chlorinated hydrocarbons such as trichlorethylene and methylene chloride; various fluorinated hydrocarbons; Examples include chlorinated and fluorinated hydrocarbons, etc., and rhodinated hydrocarbons.6 Also, examples of the volatile organic solvents include methanol, ethanol, n-delononol, 1-fcl/9nol, Alcohols such as n-butanol and i-butanol; Ketones such as mekel ethyl ketone and diclohexanone; and Amide M purified with dimethylformamide and dimethylacetamide.

Separately, NaOH, KOH, NaHCO in the aqueous medium
,.

MCO and/or ammonia, etc. are dissolved, and the solution is mixed with the above-mentioned mixed solvent solution with vigorous stirring, and on the spot, a dimer is formed, and the neutralized ethylene-( The meth)acrylic acid copolymer resin is produced, and the synergistic action of the two simultaneously causes the ethylene-vinyl acetate copolymer resin to be emulsified and dispersed in an aqueous medium.This emulsification and dispersion process is carried out in a patch method. The emulsifying and dispersing process can be carried out using a suitable emulsifying and dispersing device.The temperature during emulsifying and dispersing is determined from the azeotropic temperature of the solvent-water azeotrope used. It is also desirable to use a temperature that is at least 10 to 20°C lower.The purpose of stirring can usually be achieved in about 5 to 30 minutes.

Note that various other modified embodiments can be used in place of the emulsification and dispersion embodiment described above. For example, ethylene-vinyl acetate copolymer haze, dimeric resin, P rosin and ethylene (
The meth)acrylic acid copolymer resins are dissolved in separate solvents, or only these two types and the remaining one type are dissolved in separate solvents.

The emulsification and dispersion step thus obtained is followed by an evaporation step in which water-immiscible solvents and polar organic solvents are evaporated and removed, and a portion of the water is further evaporated until a desired ethylene-vinyl acetate copolymer resin concentration is obtained. At least remove it. The evaporation step can be carried out in a variety of ways using different types of evaporators. The evaporator is preferably a baffle-free steam-jacketed evaporator that is stirred by a turbine or paddle stirrer. Further, it is desirable to use an appropriate reduced pressure for evaporation. The evaporation is the most +ll1llf of the dispersion.
but at least 40% by weight solids, preferably 4
Allow the water to evaporate between 0 and 60 fI-chi.

Note that the dispersion liquid contains a dimeric surfactant.

Due to the presence of drosin soap, troublesome foaming often occurs during the evaporation process, but by limiting the evaporation to evaporation at the liquid surface and controlling it to prevent boiling within the liquid. ) Can prevent foaming. Further, the combined use of a water-immiscible solvent and a somatic organic solvent is very effective in preventing foaming. Furthermore, measures such as using a suitable commercially available antifoaming agent or installing a mechanical foam breaking device are also effective in preventing foaming.

In the above evaporation step, the dimer, drosine and ethylene-(meth)ac IJ used in emulsification and dispersion step 8 are
A: Ammonia and organic amines in the alkaline agent used to neutralize the acid copolymer resin are removed by volatilization.
After completing the evaporation plant, add an appropriate amount of alkaline agent (for example, NaO
It may be desirable to additionally add H, KOH, NaIC0s, KHCObl, aqueous ammonia, etc.). In addition, when free dicaptic P6 gin is contained in the polyethylene-vinyl acetate copolymer*fat dispersion of the present invention, it is vaporized in the coating film. It is often rumored to improve the water resistance, adhesion, and surface tackiness of paint films. In such a case, if you consciously add an excess amount of dimeric wood rosin to the amount required as a surfactant in advance and also use an appropriate amount of ammonia as an alkaline agent, it will be possible to improve the The ammonia is removed for 7 seconds, and the appropriate amount of free dimeric drosin is incorporated into the dispersion.

(Effects of the Invention) In the ethylene-vinyl acetate copolymer resin dispersion of the present invention, dilucent soap is used as a surfactant, and neutralized ethylene is added to this as a protective colloid. - Since the (meth)acrylic beak copolymer rosin is used in combination, the amount of surfactant and protective colloid agent required to obtain a stable dispersion is lower than when each is used alone. can be significantly reduced. To this end, the aqueous dispersion of the present invention is characterized by
The adhesion and heat sealability of the coating film can be improved compared to known dispersions made using only 7 soap and known dispersions made using only the same protective colloid. Furthermore, compared to known dispersions using only the same protective colloid agent, the minimum film forming temperature can be lowered by 1 degree Celsius, and the blocking properties of the coating film can be improved. In addition, compared to known dispersions using only the same surfactant, the stability can be improved, and this stability improvement effect is particularly evident in the ethylene-vinyl acetate copolymer of ultrapolymer with Ml of 2 or less. This is noticeable when the combined resin is dispersed.

In particular, according to the invention the vinyl acetate content is between 10 and 4.
There is no need for high-temperature heating during coating, which is required when using a hot-melt type resin with a diameter of 0 weight and an MI of 0.1 to 400, and the same resin can be used in a solvent-soluble type. There is no risk of fire, bleach pollution, or deterioration of the working environment as would be the case.

Since the aqueous dispersion of the present invention has such excellent properties, it can be advantageously used as a heat-sealable pressure-sensitive adhesive. For example, a curtain coater, alpha coater, gravure coater, brush, spray gun, etc. can be used to coat the surface of various base materials such as paper, aluminum foil, plasti such as I-lipropylene film and polyethylene terephthalate film, Kufilm, and non-woven fabric. If it is applied to the entire surface or partially to a coating thickness of 1 to 30 μm, preferably 1 to 10 μm, and dried using a P dryer, heater, etc., it will be thermally adhesive and the main substrate ( films, labels, etc.) can be easily obtained.

These heat-adhesive base materials are widely used in
Tocoat agent, print lamination, pristano!
It can be advantageously used in fields such as skin pockets, pouches, pockets, cap seals, flat punches, search containers, press throughpers, and other fields.

This aqueous dispersion can also be used as a coating agent and a processing agent for fibers and paper. Furthermore, this dispersion can be used for various purposes alone or in combination with various latexes, solutions, resin emulsions, etc.

(Examples, etc.) Hereinafter, the present invention will be further described in detail by giving Examples, Comparative Examples, and Test Examples.

Example 1 Vinyl acetate content: 287, ethylene-vinyl acetate copolymerization volume: 1 and MIo, 15! ff1100g, commercially available Daimale, Kusu (8-wo-Less Chemical Co., Ltd. fv-
John Company product name) 6.7 i and ethylene-acrylic acid copolymer resin (acrylic acid content 15% by weight, melting point 9
2° C.) was dissolved in a mixed solvent of 415 g of cyclohexane and 52 p of low propyl alcohol. In a separate vessel, a solution of 0.81 NaOH and 3.9 g of ammonia water (25 weights of ammonia-containing bone [9 g)] dissolved in 210 g of water was gradually added dropwise to the mixed solvent solution while stirring to emulsify. Ta. Initially, a mold-type oily dispersion was produced, which gradually thickened during stirring, and a phase transition occurred midway through, resulting in a 3W-type dispersion. The emulsification was carried out using a homomixer (#Shuukika Kogyo Co., Ltd. product name) for 12 hours.
This was carried out while stirring Or, p, and m, and stirring was continued for 10 minutes even after the phase transition.

The resulting emulsion was then transferred to a glass container equipped with a turbine type stirrer, and the solvent and a portion of the water were removed by evaporation at 55 DEG C. and a reduced pressure of 40-50 Peng Hg. Since the solid content of the dispersion liquid immediately after the solvent was distilled off was about 33%, about 100 g of water was further distilled off until the solid content reached about 5 m2. Approximately 49 clots were formed during evaporation. The recovery rate of the solvent mixture was 91%, and the resulting dispersion was 210%.
The solid content was 44 g.

Example 2 100 g of ethylene-vinyl acetate copolymer resin (vinyl acetate content 28% by weight, MIO, 5), Daimale, Kusu 6
．． 7 II and ethylene-acrylic acid co-polymer resin (acrylic acid content 1115%, melting point 92'C) 10#
was dissolved in a mixed solvent of 415 g of cyclohexane and 52 g of -1-propyl alcohol, and in the same manner as in Example 1 except that an aqueous dispersion 212Ii was obtained.

Coagulation corporation during evaporation 39, recovery rate of solvent mixture 89,
The solid content of the resulting aqueous dispersion was 45% by weight @ Example 3 Ethylene ζ vinyl acetate copolymer resin (vinyl acetate content 2
8% by weight, MIo, 5) 100g, Dymarex 6.
79, and ethylene-acrylic acid copolymer resin (acrylic acid-containing i#20% by weight, MI500) 1 (l),
Aqueous dispersion 205I was obtained in the same manner as in Example 1 in other respects.

The solidified content during evaporation is approximately 311, and the recovery rate of the solvent mixture is 91.
%, the solid content of the aqueous dispersion is 463! Example 4 Ethylene-vinyl acetate-acrylic acid terpolymer resin (
100 g of Debon Company's product name L-Pax 4260, vinyl acetate content 28% by weight, M1150, acid value 6), 6.7 g of Daimaret, and ethylene-acrylic acid copolymer resin (acrylic acid content 15% by weight). H, melting point 92℃) 1
0! i was dissolved in 383 g of benzene and i-7' mouth alcohol 849 (D mixed solvent). In a separate vessel, 0.81 NaOH and aqueous ammonia (ammonia content 25% by weight) were added to 210 liters of water. In the same manner as in Example 1, the solution of 351 was gradually added dropwise to the mixed solvent solution of Oki to emulsify it.

The resulting emulsion was transferred to a glass container equipped with a turbine type stirrer, and a portion of the solvent and water was evaporated.

For its evaporation, the emulsion bottle was heated to 55°C, and the pressure was reduced to 40 to 50 maHg using a vacuum aspirator.
A method was used in which the contents of the container were stirred and evaporated while stirring.

The resulting dispersion was 2201, and its solid content was 49 wt. T? c. During its evaporation, about 79 g of coagulum was formed, and the recovered amount of solvent mixture was 88 wt.

Example 5 Ethylene-vinyl acetate copolymer resin (vinyl acetate content 25% by weight, MI2) 501 Ethylene-vinyl acetate copolymer resin (vinyl acetate content 25% by weight, MI 400
) 50 #, Dymarex 6.7 II.

and ethylene-acrylic acid copolymer resin (acrylic acid content: 15 FK, melting point: 92°C) 101, benzene 3
It was dissolved in a mixed solvent of 83 g and 1-propyl alcohol 84I. Thereafter, in the same manner as in Example 4, an aqueous dispersion 209Jl'i was obtained.

The solidified content during evaporation is 1 g, and the recovery rate of the solvent mixture is 9
The solid content of the 0% aqueous product was 47 parts by weight and 1 part by weight.

Example 6 Ethylene-vinyl acetate copolymer resin (vinyl acetate containing 1
i28 weight ratio, MI 0.5) 150 Jil, Nono Rough In Wax (melting point eo°C) 15.9. Ethylene-
Acrylic acid copolymer resin (115% by weight of acrylic acid, melting point 92°C) 151 Dimarex 10I, and pentaerythritol ester of polymerized rosin 3ON'i,
Cyclohexane 788Ii and n-gropanol 92g
f! in a mixed solvent of ! ! 400ml of water in a separate container
A solution obtained by dissolving 1,511 parts of NaOH and 619 parts of aqueous ammonia (fli 25% by weight containing ammonia) in M was gradually added dropwise to the mixed solvent solution to emulsify it. Thereafter, in the same manner as in Example 1, an aqueous dispersion of 390//l was obtained.

The solidified content during evaporation was 71%, the recovery rate of the solvent mixture was 91%,
The solids content of the aqueous dispersion was 48%.

Example 7 Ethylene-vinyl acetate copolymer resin (vinyl acetate functional content 28 wt%, MI 0.5) 10011. Dimarex 6.7 N, and ethylene-methacrylic acid copolymer (methacrylic acid 1i15 double lid, M115) 1
0F'Th, cyclohexane 4159 and n-propyl alcohol 52II, otherwise the same as in Example 1 (and aqueous dispersion 205#t
"obtained." The solidified content during evaporation was 2 g, and the recovery rate of the bath agent mixture was 90.
Aqueous content obtained #! The solid content of the L product was 43% by weight. 'Comparative Example 1 The same ethylene-vinyl acetate copolymer resin 100Ji' used in Example 1 and Dimarex 15, u't-
, 409 g of cyclohexane and 51.9 g of n-propyl alcohol. 20ml water in a separate container
In 7.9, NaOH 0,81 and ammonia water (ammonia-containing t25 t) 3I were dissolved and emulsified while gradually dropping into the above mixed solvent solution, and the following procedure was carried out in the same manner as in Example 1. and aqueous dispersion 208j'
I got it.

The solidified content during evaporation was 411. The recovery rate of the mixed bath was 91 L, and the solid content of the aqueous dispersion was 46 weights.

Comparative Example 2 The same ethylene-vinyl acetate copolymer resin 100.9. Polymerized rosin (Haki,
Less Chemical Corporation (trade name: Polyveil Resin) 6.7F and ethylene-acrylic acid copolymer resin (acrylic acid content: 15%, melting point: 92°C) 1
0g was dissolved in a mixed bath medium of cyclohexane 415I and n-propyl alcohol 529, and the following Comparative Example 1
It was emulsified in the same manner as above and evaporated in the same manner.

Most of the copolymer resin solidified during evaporation. The coagulum was removed by filtration, and the remaining dispersion was allowed to stand at room temperature for one day, causing the dispersion to form a portion of the aqueous phase.

Comparative Example 3 The same ethylene-vinyl acetate copolymer resin 75y1 used in Example 1, the same ethylene-acrylic acid copolymer resin 751'fH used in Example 1, cyclohexane 533I, and n-propyl alcohol 66jl
was dissolved in a mixed solvent of

In a separate container, 270 I of water, 10.9 ml of NaOH'31 and aqueous ammonia (ammonia content 25 weight i!-%) l
l! The dissolved mixture was gradually dropped into the mixed solvent solution to emulsify it. The emulsification was carried out using a T-mixer, and a phase transition occurred during the emulsification. Thereafter, evaporation was performed in the same manner as in Example 1 to remove a portion of the solvent and water.

Approximately 1,511 solids were produced during evaporation, the recovery of the solvent mixture was 89 parts, and the solids content of the aqueous dispersion was 45 parts by weight.

Test Example This example is a comparative test of heat seal strength, minimum film forming temperature, and blocking property for the dispersions obtained in Example 1 and Example 5 and the dispersions obtained in Comparative Example 1 and Comparative Example 3. That's what I did.

That is, the dispersion obtained for each of them has a specific elongation/I
It was applied to a base material of J propylene film (trade name: 4ylene P-2161, manufactured by Toyobo Co., Ltd., thickness: 40 μm) under the following conditions and dried.

Application method: Using Baker applicator Drying conditions after application: Heat seal strength,
The results of tests on minimum film forming temperature and blocking properties were as shown in the table below.

(1) Heat-sealing strength The coated surfaces were pressed together for 1 second under heat-sealing conditions of 2 to 7 cm at 120°C (using a heat-seal tester manufactured by Tester Sangyo Co., Ltd.). Regarding the obtained laminated film, JI8Z-1707 (Glasstic Film for Food Packaging - Heat Seal Strength) K Therefore, a T-peel test was conducted. East seal indicates rupture of the base material.

(2) Minimum film-forming temperature The minimum film-forming temperature was measured using a Glublock manufactured by Waliae.

(3) Professional, Kingability According to JIS Z-1515, the coated surfaces were stacked together and left in a constant temperature bath at 40°C for 48 hours, then the T-peel strength of the combined nine films was measured, and the following procedure was performed. Evaluated/None at all...Peel strength is 25■
None if the width is 1tII or less... If the same strength is 1 to 10JI, there will be a slight crease...
・When the same strength is 50JiF or more As is clear from the results shown in the table, those using the dispersions of Examples 1 and 5 have a higher strength than those using the dispersions of Comparative Examples 1 and 3. The heat-sealing strength is extremely high, and in particular, the values of Example 1 are significantly superior to those of conventional heat-sealable films. In addition, the dispersion of Comparative Example 3, which was dispersed using only the ethylene acrylic copolymer resin (colloidal agent), was able to form a uniform and transparent coating on the substrate due to its high minimum film-forming temperature. More thermal energy is required to form a film than in the case of the dispersions of Examples 1 and 5. In the dispersions of Comparative Examples 1 and 3, a large amount of surfactant and protective colloid is used to make the dispersion stable, so the adhesiveness (heat seal strength) is poor. be. On the other hand, in Examples 1 and 5, since a surfactant and a protective colloid were used in combination, a stable dispersion could be obtained even if a small amount of each was used, and therefore the heat seal strength increased. , the minimum film-forming temperature and resistance to processing and kinging were all improved.

Claims (1)

[Scope of Claims] 1) An ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 10 to 40% by weight, and a neutralized ethylene-(meth)acrylic acid copolymer resin with dimeric wood rosin soap. An aqueous ethylene-vinyl acetate copolymer resin dispersion obtained by dispersing the following in an aqueous medium. 2) The aqueous dispersion according to claim 1, wherein the ethylene-vinyl acetate copolymer resin has a melt index of 0.1 to 400. 3) The aqueous dispersion according to claim 1, wherein the ethylene-vinyl acetate copolymer resin has a melt index of 0.1 to 2.