JPS60195173A - Pressure-sensitive adhesive - Google Patents

Abstract

PURPOSE:To provide the titled adhesive having excellent adhesive strength, etc., and composed of an aqueous dispersion of a synthetic resin produced by the emulsion polymerization of a polyvalent vinyl compound with a sulfonic acid group-containing alpha,beta-unsaturated monomer, etc., and further carrying out the emulsion polymerization of a specific alkyl (meth)acrylate-containing monomer, etc. CONSTITUTION:(A) 100pts.wt. of a monomer composed of (i) 50-100% alkyl (meth)acrylate containing 4-12C alkyl group and (ii) 50-0% other copolymerizable alpha,beta-ethylenic unsaturated monomer is subjected to the emulsion polymerization in water in the presence of (B) 0.3-20pts. of a synthetic resin dispersion prepared by the emulsion polymerization of (iii) 1-10wt% water-soluble alpha,beta- ethylenic unsaturated monomer, (iv) 0.1-5% polyvalent vinyl compound and/or polyvalent allyl compound, (v) 0.1-3% alpha,beta-ethylenic unsaturated monomer and (vi) 82-98.8% other copolymerizable alpha,beta-ethylenic unsaturated monomer, in water. The obtained aqueous dispersion of a synthetic resin having a glass transition point of -60--10 deg.C is used as a main component of the objective adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a water-dispersed coating material that has excellent adhesive strength to adherends such as films, sheets, and molded articles made of polyolefins such as polyethylene and polypropylene, and has excellent roll coating workability. It relates to pressure adhesives.

In recent years, in the field of pressure-sensitive adhesives, resource-saving, non-polluting,
Due to the increasing demand for solvent-free adhesives from a safety and health perspective, the conventionally mainstay organic solvent-based pressure-sensitive adhesives are being replaced by water-dispersed adhesives.

However, in the case of water dispersion type, in terms of adhesion performance, adhesion to polyolefin adherends such as polyethylene and polypropylene with low surface energy is not sufficient, and synthetic resin aqueous dispersion has large thixotropic properties, so it is difficult to roll. There is a drawback in terms of coating workability that uneven streaks occur during coating, and there has been a strong demand for improvement.

By the way, it has been known to produce synthetic resin aqueous dispersions by multi-hole (ES polymerization) method for the purpose of improving adhesive properties and roll coating workability. In general, it is difficult to maintain a good balance between adhesive strength and roll coating workability in this method, and even when increasing the particle size for the purpose of improving roll coating workability, it is difficult to maintain a good balance between adhesive strength and roll coating workability. There was a problem that aggregates were formed.Especially when the final synthetic resin has a flexible glass transition point (Tg) of -60 to -10°C, the seed synthetic resin aqueous dispersion is α added from the eye,
There was a major problem in that the β-ethylenically inert saturated monomer was absorbed into a swollen state and was likely to aggregate, making it difficult to industrially mass-produce it in a stable state.

There is a method of using a large amount of emulsifier as a means of stabilizing this, but this method does not increase the particle size and also deteriorates water resistance, so the disadvantage is that it cannot fully achieve the purpose of Shirahatsu. was there.

As a result of intensive research in order to improve the above-mentioned problems, the present inventors have discovered that a polyvalent vinyl compound and/or a polyvalent allyl compound and an α,β-unsaturated phase monomer having a sulfonic acid substituent A synthetic resin aqueous dispersion obtained by emulsion polymerization of a monomer mixture contained in water as a seed, and a monomer (mixture) containing a specific alkyl (meth)acrylate as a main component.
The aqueous synthetic resin dispersion obtained by emulsion polymerization is capable of stable multi-stage emulsion polymerization even when the glass transition point (Tg) is -60 to -10°C and is flexible. It has been found that by using the above-mentioned method, a water-dispersed pressure-sensitive adhesive having excellent adhesive strength to polyolefins and excellent roll coating workability can be easily obtained, and the present invention has been completed based on this finding.

That is, the present invention provides water-soluble α, β, β-ethylene saturated monomer (A) 1 to 10
Weight %, each valent vinyl compound (I) and/or polyvalent allyl compound (
BLO 61-5%, sulfonic acid 11 ￥4ヅ1〕ilj α, β,
β-ethylene saturated l1i-J, ; integral (c'l O,1
~3xkM %, as well as 111% and other α,β-ethylenically unsaturated saturated monomers) 82-9
Synthetic resin dispersion obtained by emulsion polymerization of 8.871tIL1% in water. Alkyl (meth)acrylate fE with
150-100 't''-ti)% of other α,β-ethylenically unsaturated phases copolymerizable with (F) 50-θ
Emulsify a monomer mixture consisting of 100', i old, one part in total water (combined glass transition point (Tg)
The present invention provides a pressure-sensitive adhesive characterized in that the main ingredient is an aqueous dispersion of a synthetic resin having a temperature of -60 to -10°C.

The water-soluble α,β-enalenically unsaturated extender (Al) used in the present invention is a monomer that is itself water-soluble and whose homopolymer is water-soluble. However, preferred examples include (meth)acrylic acid, dimethylaminomethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and hydroxyethyl (meth)acrylate.
Meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylamide, etc. are available.

Polyvalent vinyl compound and/or polyvalent allyl compound (B)
Examples of polyvalent vinyl compounds include divinyl compounds and trimethacrylate compounds, and examples of polyvalent allyl compounds include diallyl compounds and triallyl compounds. Among them, preferred examples include divinylbenzene, ethylene glycol dimethacrylate V-1-11, ro-butylene dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and di-allyl phthalate. Among them, divinylbenzene and diallyl phthalate are particularly preferred.

α,β-ethylenically unsaturated monoh)YJ=(C) having a sulfonic acid fM′ substituent includes vinyl aromatic sulfonic acids such as vinylbenzenesulfonic acid, vinylsulfonic acid, (meth)acrylic 41i? Examples include sulfoalkyl esters of α-methylenecarboxylic acid such as -2-sulfoethyl and -2-sulfopropyl (meth)acrylate, and ammonium salts or metal salts thereof. Also included are sulfonic acids containing an allyl group or metaallyl group represented by the following general formula (1) or (2), and ammonium salts or metal salts thereof.

(In the formula, S R+ is hydrogen or a methyl group, R3 is an alkyl group, cycloalkyl group, oxynalkyl group, and A has 2 carbon atoms.
-4 alkylene group, n is 0 or a positive integer, Ml means an alkali metal or alkaline earth metal ammonium, an organic amine base or an organic quaternary ammonium base.

) Specific examples of the compounds represented by the general formulas (II and (2)) include Mt.E H7c-COOC,21(,.

NaO,S -CH-Coo (CH7C1■20)
2oCH2C8=CI-I,,lICC00C12H2
a Nap, 5-CH-Coo (CH, CI, CH2O
),. CH20H=CH6, etc. are mentioned.

Joint■lt joint rjJ4ii! , 7'', Takunosen's α,β-ethylenically unsaturated monomer (1)) include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethyl alkyl esters. , preferably alkyl esters having 1 to 8 carbon atoms, vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatic acid (sixth-class carboxylic acid), and vinyl compounds containing alkyl esters such as acrylonitrile and N-vinylpyrrolidone; Aromatically unsaturated JIj-1ii monomers such as styrene, α-styrene, vinyltoluene, etc. are included.

If the total amount of these (A1-(Di monomers) is 10014i4H1%, then
- Ethylene non-drowning phase HA 1-10'? h amount%
, polyvalent vinyl compound and/or polyvalent allyl compound B)
0.1 to 5 weight percent, α, β with sulfonic acid substituents
- Ethylenically unsaturated phase monomer (C) 0.1 to 3% navy blue,
Other copolymerizable α,β-ethylenically unsaturated phases-11
tjij: Body 0)) The ratio is 82 to 98.8% by weight.

Synthetic resin aqueous dispersions containing the water-soluble α,β-ethylenically inorganic phase monomer (A) in an amount of 1 cannot be stably produced. Also, polyvalent vinyl compounds and/or polyvalent allyl compounds (Bl
If the amount used is less than o, 114 1%, synthetic JiAj
It cannot be produced as a fat/water dispersion, and if it exceeds 5%, the adhesive strength to the polyolefin cheek adherent will decrease.

α with further sulfonic acid substitution) &.

The amount of β-ethylenically unsaturated mono]lIt isomer (C) used is o
If the content is less than 151i%, a synthetic resin aqueous dispersion cannot be stably produced, and if it exceeds 1fi'%, the roll performance ViE will decrease.

In the first stage emulsion polymerization carried out in the present invention, organic thiol compounds such as t-dodecyl mercaptan and lauryl mercaptan, organic halogen compounds such as chloroform and carbon tetrachloride, etc. are further added as necessary. Molecular weight can be adjusted using known and commonly used chain transfer agents, and in some cases, anionic emulsifiers such as sodium dodecylbenzenesulfonate, alkaryl holiedel sulfate; polyoxyethylene nonylphenol ether, Nonionic emulsifiers such as oxyethylene-polypropylene block copolymer; cationic emulsifiers such as laurylpyridinium chloride, cetyltrimethylammonium bromide, etc. can also be used; You can also do this.

As radical-generating catalysts commonly used in emulsion polymerization, known catalysts for cell use such as hydrogen peroxide, ammonium persulfate, potassium persulfate, t-butyl hydroperoxide, etc. can be used, and such polymerization initiators and 41 can also be used in the form of a redox initiator in combination with known elementary substances such as ascorbic acid or sulfite. Further, the polymerization temperature is preferably in the range of 30 to 90°C, and the resin solid content is preferably in the range of 10 to 50% by weight.

It is preferable that the conversion rate of unsaturated monomers in the first stage emulsion polymerization is high, but if the conversion rate is 60% by weight or more, unreacted unsaturated 9-phase monomers (A ) to ) are consumed in the second and subsequent reactions, so there is no particular problem.

The synthetic resin aqueous dispersion that becomes the rod obtained by reacting as described in 1 above is pH-adjusted as desired, and the second and subsequent polymerization reactions are subsequently carried out. It's okay to use things. At that time, the use of the synthetic 4+j・i aqueous dispersion 111 as a seed is the alkyl (meth)acrylate (IC) having an alkyl group having 4 to 12 carbon atoms and other α, β- The amount is usually 03 to 20 parts (solid electrolyte) per 100 parts by weight of the I-11 substance (mixture) consisting of the ethylenically unsaturated phase monomer (F). Carbon number 4 to 1 used in the second stage and beyond
Alkyl (meth)acrylate having 2 alkyl groups [
The most typical example is n-butyl (meth).
Examples include hexyl (meth)acrylate and nonyl (meth)acrylate. Furthermore, other α,β-ethylenically unsaturated jN,'iiH forms (Fl and radical generation catalysts include unsaturated monomers 4A used in producing the seed synthetic resin aqueous dispersion) to (Dl Any of the above-mentioned chain transfer agents can also be used, if necessary, for the purpose of adjusting molecular groups.

Regarding the emulsifier, all known and commonly used emulsifiers that can be used to produce the seed synthetic resin aqueous dispersion can be used, but it is also possible to use emulsifiers without using any emulsifier. For the purpose of obtaining a product with excellent strength and roll coating workability, 2.
In the subsequent reactions, it is preferable to polymerize the emulsifier in a small amount or in its absence. The #-mer (mixture) to be reacted in the second and subsequent stages is added by adding dropwise glume to Motoyama (
, Even if 1-1 of Hirasho is added to 1- of multi-throws, it is white. The reaction temperature after the second stage 11 is preferably in the range of 60 to 90°C.
651EtjTi% is preferably increased.

The synthetic resin aqueous dispersion thus obtained can be applied as it is as a pressure-sensitive adhesive to paper, cloth, plastic glue, film, etc.; Known and commonly used stabilizers, thickeners,
Appropriate amounts of pigments, fillers, plasticizers, wetting agents, antifoaming agents, etc. may be added, and regardless of how they are used, the present invention has excellent adhesive strength to polyolefins and excellent roll coating workability. The adhesive is applied.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Incidentally, parts and percentages in the examples are based on one person's weight, unless otherwise specified.

Example 1 910 parts of deionized water and 1.5 parts of polyoxyethylene nonylphenol ether were added to a reaction vessel equipped with a stirrer, a condenser, a thermometer, and a dropping funnel [7, while stirring, the internal temperature ff:so° The temperature was raised to C. After introducing nitrogen gas into the container, 2 parts of acrylic acid, 0.5 parts of divinylbenzene-0.5 parts of sodium styrene sulfonate, and 15 parts of ethyl acrylate were added.

62 parts of n-butyl acrylate and 2 parts of ammonium persulfate were charged. Thereafter, the same temperature was maintained for 1 hour to complete the first stage reaction. The solid content was 5.1 parts, and the polymerization conversion rate was 92%.

Next, after injecting 5 parts of 25% ammonia water, 30 parts of acrylic acid, 300 parts of n-butyl acrylate, 470 parts of 2-ethylhexyl acrylate, 200 parts of vinyl acetate, and 0.5 part of t-dodecyl mercaptan were added at the same temperature. and a mixture of 6 parts of μ ammonium persulfate and 100 parts of deionized water were injected separately over a period of about 6 hours, held at the same temperature for an additional hour, and then cooled. 2050 parts of Synthesis I04 aqueous dispersion (solid content 507%) was obtained. Note that the Tg of this synthetic resin was approximately -40°C.

This synthetic resin aqueous dispersion produced a small amount of aggregates, had good adhesive strength and roll coating workability, and was excellent as a pressure-sensitive adhesive.

Comparative Example 1 910 parts of deionized water, polyoxyethylene nonylphenol ether t5S, and 05 parts of sodium styrene sulfonate were added to the same reaction vessel as in Example 1, and the internal temperature was raised to 80°C while stirring. Furthermore, after introducing nitrogen gas into the container, 62 parts of acrylic acid, 05 parts of divinylbenzene,
15 parts of ethyl acrylate, 3 parts of n-butyl acrylate
A mixture of 62 parts, 470 parts of 2-ethylheginyl acrylate, 200 parts of vinyl acetate, 0.5 parts of t-dodecylmercaptan, and 5 parts of ammonium persulfate and 10 parts of deionized water.
A synthetic resin aqueous dispersion for comparison (solids content 50.4%, Tg approx. -40℃)
It's a good deal for the 2035th part. This synthetic resin aqueous dispersion had problems with adhesive strength and roll coating workability, and was inferior as a pressure-sensitive adhesive.

Comparative Example 2 The first stage reaction was completed in the same manner as in Example 1, except that the addition of divinylbenzene and sodium styrene sulfonate was omitted and the amount of n-butyl acrylate added was changed to 33 parts. The polymerization conversion rate was 96%. Next, a second stage reaction was carried out in the same manner as in Example 1, and a synthetic resin aqueous dispersion for comparison (solid content 500%, Tg approximately -40°C) was prepared.
Obtained 2nd prize in 1875. This synthetic ml adhesive produced an extremely large amount of agglomerates, had problems in roll coating workability, and was inferior as a pressure-sensitive adhesive.

Comparative Example The first stage reaction was completed in the same manner as in Example 1, except that the addition of divinylbenzene was omitted and the amount of n-butyl acrylate added was changed to 62.5 parts. Polymerization conversion rate is 93
%Met. Next, a second stage reaction was carried out in the same manner as in Example 1, and a synthetic resin aqueous dispersion for comparison (solid content: 50
．． 3%, Tg approximately -40°C) 1964 parts were obtained. This synthetic resin aqueous dispersion has a composition of 1 and 2. Comparative Example 4 Example except that the addition of sodium styrene sulfonate was omitted, and the addition of n-butyl acrylate was changed to 2.5 parts. The first stage reaction was completed in the same manner as in 1. The polymerization conversion rate was 92%. Next, a second stage reaction was carried out in the same manner as in Example 1 to obtain 1947 parts of a synthetic resin aqueous dispersion for comparison (solid content 50, 6% bTg about -40°C). This synthetic resin aqueous dispersion is
'7<, Shuttle-1, fs-writer 1 pressure, P side leg 1 failure, counterfeit t1 appalled, old obscene Lshinha 4 = a ma, oh, go.

The same procedure as in Example 1 was carried out, except that the monomer mixture that had surfaced in the second stage reaction was divided into 6 parts and 1 part was added in multiple stages every 30 minutes. Type 50.
7%, Tg-40"C) was obtained. This synthetic resin dispersion produced a small amount of aggregates, and had adhesive strength and roll coating workability of 0.
It had excellent pressure-sensitive adhesive properties.

Example 3 The first step was carried out in the same manner as in Example 1 except that 2-ethylhexyl acrylate was used instead of n-butyl acrylate.
I have finished the first step of the reaction. The solid content was 5.1 parts, and the polymerization conversion rate was 94%. Next, 300 parts of n-butyl acrylate, 470 parts of 2-ethylhexyl acrylate
The second stage reaction was carried out in the same manner as in Example 1 except that 820 parts of 2-ethylhexyl acrylate and 150 parts of vinyl acetate were used instead of 20 parts of vinyl acetate, and the synthetic resin aqueous dispersion ( Solid content 50.7%, Tg approximately -55℃)
2050 copies were obtained. Synthesized in the keratin (I7Ill), which produces a small amount of acid 11♂ products,
and adhesive strength and roll 411 formability of 9%,
It was an excellent pressure-sensitive adhesive.

Example 4 In a reactor similar to Example 1, 910 parts of deionized water, 5%
5 parts of FeC6,.6H20 aqueous solution and 2 parts of sodium pyrosulfite were added, and the internal temperature was raised to 60° C. while stirring. After introducing nitrogen gas into the container, acrylic acid 2
1 part, 2 parts of the compound represented by diallylph, 15 parts of ethyl acrylate, 62 parts of n-butyl acrylate, and 2 parts of ammonium persulfate. Thereafter, the same temperature was maintained for 1 hour to complete the first stage reaction. Polymerization conversion rate is 96
%Met.

Next, after injecting 5 parts of 25% ammonia water, 30 parts of acrylic acid and 300 parts of n-butyl acrylate were added at the same temperature.
470 parts of 2-ethylhexyl acrylate, 200 parts of vinyl acetate, a mixture of 0.5 parts of t-dodecylmercaptan, a mixture of 3 parts of ammonium persulfate and 50 parts of deionized water, and 3 parts of sodium pyrosulfite and deionized water. A mixture with 50 parts of ionized water was injected into each mixture over a period of about 6 hours, kept at the same temperature for 1 hour, and then cooled to obtain the desired synthetic resin aqueous dispersion (solid content: 50 parts). .7%, Tg approximately -40
℃) 2060 parts were obtained. This synthetic resin aqueous dispersion contained few aggregates, had good adhesive strength and roll coating workability, and was excellent as a pressure-sensitive adhesive.

Test Example 1 The amount of aggregates produced in the aqueous synthetic resin dispersions obtained in Examples 1 to 3 and Comparative Examples 1 to 4 was measured, and adhesive performance tests (adhesive force test, holding force test, adhesive force test) and A roll coating workability test was conducted. The results are shown in Table-1. The method for measuring the amount of aggregate produced, the method for preparing samples, the method for testing adhesive performance, and the method for testing coating workability were as follows.・Measurement of the amount of 0-aggregate formation - After separating the aggregates in the synthetic resin aqueous dispersion using a 200-mesh wire mesh, washing with water and drying, the ratio to 1 weight of total solid content was calculated.

Preparation of O samples - Each synthetic resin aqueous dispersion was dried to a thickness of 25μ so that the evaporation residue after drying was 30.9'/m2.
It was applied with an applicator onto a polyester film of 100 m and dried for 2 minutes at 11D'C. Then 20℃, 65
A sample coated with a pressure-sensitive adhesive on one side was prepared by leaving the coated surface exposed in a constant humidity room with a pressure-sensitive adhesive for one day and one night.

O Adhesive performance test (1) Adhesive strength test: Cut the sample into 25 mm width, 5 m
Each sample was pressed onto a polyethylene plate, a polypropylene plate, and a stainless steel plate by moving a 2 to 9 rubber roller back and forth once at a speed of rv/sec, and then left for 20 minutes. Next, the adhesive force was measured by peeling at a peeling angle of 180 degrees and a peeling speed of 300 mm/min.

(2) Cut the retained crab sample into 25 mm width pieces and cut them at a speed of 2 to 9 mm at a speed of 5 to 5 mm/sec until the adhesive surface is 25 mm x 25 mm.
The rubber roller was moved back and forth once to press it onto the stainless steel plate, and then it was placed in a constant temperature room at 40°C x 65% lj II.
Hang it vertically for 0 minutes, then apply 1kl parallel to the adhesive surface of Shikarunojiko? A dead load was applied, and the time until the weight slipped off was measured, and this time was taken as the holding force.

(3) Adhesiveness: ■ A ball rolling test according to the Dow method was conducted under the conditions of 20'' (, × 65% IHI), and was indicated by a ball 16 of 'A+: a ball that was stationary on the sample surface.

O-roll coating workability test - 25% ammonia water was added to a synthetic resin aqueous dispersion, the p■-Tf was adjusted to about 8, and a thickener was used as a thickener (Bonco) 3750 (manufactured by Dainippon Ink & Chemicals Co., Ltd.) (appropriate amount) to reduce the viscosity to approximately 40[1[]cp
s (BM type viscometer, rotor A4). For these samples, chrome-plated iron rolls with a diameter of 16
Using a 6-roll test reverse roll coater (manufactured by Nika Rino Kikai Co., Ltd.) with 0+ni, width 450 mm (metering roll and applicator roll are the same size), the leveling performance at each coating speed was measured. Judgment was made based on the appearance of the dried paint film. The rotational speed and coating speed ratio of each roll are constant at a metering roll speed of 1 (near applicator roll speed: coating speed = 1:5.3:3, and this ratio remains constant even if the coating speed changes). Also, the dry film thickness is 011m.
Iil,, [4] at one river interval between the metal ring roll and the affiliator roll so that

Note that the first judgment criterion was as follows.

Claims (1)

[Claims] Water-soluble α, β-ethylenically unsaturated monomer (A) 1 to 10
Weight %, polyvalent vinyl compound and/or polyvalent allyl compound (B)
0.1 to 5% by weight, 0.1 to 3% by weight of an α,β-ethylenically unsaturated monomer (C) having a sulfonic acid substituent, and other copolymerizable α,β-ethylenically unsaturated monomers (C). Emulsify 1% of saturated phase monomer (D) s 2-98.8 in water 7
Synthetic resin dispersion 03-2Ojl obtained by combining 1j
1T amount part (solid content 7Jr f7f) as hit,
Further, an alkyl group having 4 to 12 carbon atoms (
50-100% by weight of the α,l-ethylenically unsaturated monomer (Fl) copolymerizable with meth)acrylate fFl)
The glass transition point (Tg
1. A pressure-sensitive adhesive characterized in that the main ingredient is an aqueous dispersion of a synthetic resin having a temperature of -60 to -10°C.