JPH08170061A - Water-based adhesive composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition having excellent holding power especially in a high-temperature atmosphere by adding a specific urethane- modified rosin derivative as a tackifier to an emulsion composed mainly of a poly(meth)acrylic acid ester. CONSTITUTION: This adhesive composition is produced by incorporating (A) 100 pts.wt. (in terms of solid component) of an emulsion composed mainly of a poly(meth)acrylic acid ester [preferably a polymer composed mainly of an ester of (meth)acrylic acid and a 1-18C alkyl alcohol] with (B) 1-50 pts.wt. of a urethane-modified rosin derivative produced by reacting (i) a hydroxyl- containing rosin derivative with (ii) an NCO-containing compound (e.g. tolylene diisocyanate). The component (i) is composed of preferably an ester of a rosin and a polyhydric alcohol such as ethylene glycol containing a part of the hydroxyl groups in free state and having a hydroxyl value of 10-180.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based adhesive composition, which is particularly excellent in holding power at high temperatures.
The present invention relates to a pressure sensitive adhesive composition.

[0002]

2. Description of the Related Art Conventionally, a pressure-sensitive adhesive composition has been applied to paper, plastic film or the like and used in the form of a sheet, tape, label or the like.

Various types of pressure-sensitive adhesives are known, but recently, water-based pressure-sensitive adhesives are widely used from the viewpoints of environment-friendly and hygiene and safety during work. It has become.

Recently, plastic materials such as polyethylene and polypropylene have been widely used as materials for adherends, and as a water-based pressure-sensitive adhesive composition for such plastic materials, an acrylic copolymer is used. It is known that an emulsion, emulsion such as SBR latex is used as a base polymer, and natural resin such as rosin-based resin and terhen-based resin and synthetic resin such as petroleum resin are added as a tackifier to the resulting polymer to improve physical properties. ing. In particular, rosin-based resins are widely used because they have excellent compatibility with the base polymer and have a large effect of modifying the initial adhesive force with respect to polyolefin.

[0005]

However, the addition of the rosin-based resin emulsion improves the adhesive force to the olefin, but tends to weaken the internal cohesive force of the adhesive itself, especially under high temperature atmosphere. The retention performance of was poor and often slipped or fell off.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water-based adhesive composition capable of maintaining excellent holding power even in a high temperature atmosphere.

[0007]

Therefore, the present invention provides a solid content 1 of an emulsion containing a (meth) acrylic acid ester as a main component.
With respect to 00 parts by weight, a rosin derivative having a hydroxyl group,
It is characterized in that 1 to 50 parts by weight of a urethane-modified rosin derivative obtained by reacting a compound having an isocyanate group is added.

In the present invention, the (meth) acrylic acid ester as the base resin is preferably a polymer containing an ester of (meth) acrylic acid and an alkyl alcohol having 1 to 18 carbon atoms as a main component. . Two or more kinds of these (meth) acrylic acid esters may be used in combination.

In this (meth) acrylic acid ester, the polymer may be obtained by copolymerizing the (meth) acrylic acid alkyl ester with at least one vinyl monomer copolymerizable therewith. Good.

Examples of vinyl monomers copolymerizable with (meth) acrylic acid alkyl ester include carboxyl group-containing monomers such as (meth) acrylic acid, maleic anhydride, and itaconic acid, and 2-hydroxyethyl (meth) acrylate. A hydroxyl group-containing monomer such as 2-hydroxypropyl (meth) acrylate can be used, and a nitrogen-containing monomer such as (meth) acrylic acid amide, dimethylaminoethyl (meth) acrylate, vinylpyrrolidone, styrene, It is also possible to use a vinyl group-containing monomer such as α-methylstyrene, vinyl acetate, acrylonitrile, or glycidyl (meth) acrylate.

20% by weight or less, preferably 10% by weight or less, of one or more of these vinyl monomers,
It can be used by being copolymerized with the above-mentioned (meth) acrylic acid alkyl ester.

In order to produce an emulsion of an aqueous acrylic copolymer, the monomers of the copolymer component are copolymerized in the presence of a surfactant and a polymerization initiator, using water as a dispersion medium and a reaction site.

Surfactants at the time of copolymerization include fatty acid salts, alkyl sulfates, alkylbenzene sulfonates,
Anionic surfactants such as alkylsulfosuccinates, or nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, sorbitan fatty acid ester derivatives can be used, and Two or more of these may be used in combination.

As the polymerization initiator, in addition to persulfates such as potassium persulfate and ammonium persulfate, peroxides such as hydrogen peroxide, cumene hydroperoxide and t-butyl hydroperoxide may be used. When the polymerization is carried out at a relatively low temperature, redox polymerization can be carried out using a reducing agent such as sodium thiosulfate, sodium bisulfite and sodium pyrophosphate.

Further, in order to stabilize the emulsion particles, a cellulose derivative such as carboxymethyl cellulose or hydroxyethyl cellulose, or a synthetic water-soluble polymer such as polyvinyl alcohol or its derivative may be added as a protective colloid.

Further, various salts may be added for the purpose of controlling the polymerization rate of the produced polymer, and lauryl mercaptan, in order to control the molecular weight of the produced polymer,
Chain transfer agents such as dodecyl mercaptan can also be used. Further, a small amount of a plasticizer such as dioctyl phthalate or an organic solvent may be added in order to improve the film forming speed of the emulsion particles during use.

In the present invention, a urethane-modified rosin derivative obtained by reacting an isocyanate compound with a rosin derivative having a hydroxyl group is added to the polymer compound as a tackifier.

The rosin derivative having a hydroxyl group in the present invention is preferably an ester of rosin and a polyhydric alcohol, and it is suitable to use one having a hydroxyl value of 10 to 180.

As the rosin derivative having a hydroxyl group, it is suitable to use an ester of rosin and a polyhydric alcohol in which a part of the hydroxyl groups of the polyhydric alcohol is free.

As the rosin, gum rosin, tall oil rosin, wood rosin, hydrogenated rosins thereof, asymmetrical rosin, and polymerized rosin can be used, or purified products thereof can also be used.

As the polyhydric alcohol, dihydric alcohols such as ethylene glycol, diethylene glycol and propylene glycol, trihydric alcohols such as glycerin, tetrahydric alcohols such as pentaerythritol and diglycerin can be used.

As the rosin derivative having a hydroxyl group, rosin alcohol or the like can be used in addition to the above-mentioned rosin ester.

The hydroxyl value of the rosin derivative having a hydroxyl group is preferably about 10 to 180. When the hydroxyl value is less than 10, the amount of the isocyanate compound that can be bonded to the hydroxyl group of the rosin derivative is small and the urethane bond is small.
When blended in an adhesive, the holding power in a high temperature atmosphere cannot be maintained.

If the hydroxyl value of the rosin derivative exceeds 180, the reaction with the isocyanate compound does not proceed efficiently and undissolved substances may precipitate during the reaction, which is not preferable.

Examples of the compound having an isocyanate group include tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and other isocyanates;
A compound having an isocyanate group such as an adduct compound of these isocyanates and a polyalcohol can be used.

A solution of a urethane-modified rosin derivative is obtained by adding an isocyanate compound in a state where the rosin derivative is dissolved in a solvent and heating the mixture. Water and an emulsifier are added to this solution to prepare an aqueous emulsion.

The amount of the isocyanate compound added is preferably such that the isocyanate group is approximately equivalent to the hydroxyl group of the rosin derivative and the reaction is continued until the isocyanate group disappears.

The emulsifier for emulsifying the urethane-modified rosin derivative is not particularly limited, and various cationic, anionic and nonionic emulsifiers can be used, but anionic ones are preferred. Further, it is suitable to use 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the urethane-modified rosin derivative.

The emulsification method is also not particularly limited, and in addition to the inversion emulsification method, a homogenizer, a colloid mill,
It is also possible to mechanically emulsify using an emulsifying machine such as a homomixer. At this time, it is also possible to use a solventless emulsification method of emulsifying above the softening point of the rosin derivative without using a solvent during emulsification, and also emulsifying the resin in a state where the viscosity is lowered by dissolving it in an organic solvent. It is also possible to use a solvent emulsification method in which the solvent is then removed.

The water-based adhesive composition of the present invention can be obtained by adding a urethane-modified rosin derivative to the emulsion of the (meth) acrylic acid ester. (Meta)
It is appropriate that the addition amount of the urethane-modified rosin derivative is 1 to 50 parts by weight with respect to 100 parts by weight of the solid content of the acrylic ester.

If the amount of the urethane-modified rosin derivative added is less than 1 part by weight, the effect of the present invention cannot be obtained, and if it exceeds 50 parts by weight, the amount of the (meth) acrylic acid ester is relatively reduced, and as an adhesive agent. Function is reduced.

[0032]

【Example】

(Preparation of Base Resin) [Reference Example 1] 106.8 parts by weight of water and an aqueous solution of sodium polyoxyethylene alkyl ether sulfonate were placed in a reaction vessel equipped with a thermometer, a nitrogen introducing tube, a stirrer, a dropping funnel and a cooling tube. (Nonvolatile matter 26%) and 15.4 parts by weight,
The temperature was raised to 80 ° C. with stirring while blowing nitrogen gas.

Then, acrylic acid 2-, which had been prepared in advance,
Ethylhexyl 48.5 parts by weight, n-butyl acrylate 4
8.5 parts by weight, a monomer mixture of 3 parts by weight of acrylic acid, and 10 parts by weight of a 5% aqueous solution of ammonium persulfate were dropped into the reaction vessel at the same time over 5 hours.

After the completion of dropping, aging reaction was carried out at 80 ° C. for further 2 hours to obtain an emulsion of acrylic copolymer having pressure-sensitive adhesive property. The solid content concentration of the emulsion is 4
It was 5.5%.

Reference Example 2 The composition of the monomer mixture in Reference Example 1 was changed to 2-ethylhexyl acrylate 6
Acrylic copolymer in the same manner as described in Reference Example 1 except that 9.6 parts by weight, 17.4 parts by weight of n-butyl acrylate, 10 parts by weight of methyl methacrylate, and 3 parts by weight of acrylic acid were used. An emulsion of The solid content concentration of the emulsion was 45.1%.

(Preparation of tackifier) (Example) [Example 1] In a reaction vessel equipped with a thermometer, a nitrogen introducing tube, a stirrer, a cooling tube and a drainage tube, a glycerol ester of asymmetric asymmetric rosin ( Harima Kasei Co., Ltd. product name: Harrier Star D
S-90S: acid value 8: hydroxyl value 25: softening point 95 ° C.) 1
00 parts by weight and 75 parts by weight of toluene as a solvent were charged, and the mixture was stirred while blowing nitrogen gas and the temperature was raised to 100 ° C. to completely dissolve the rosin ester.

Then, the mixture was cooled to 50 ° C., and 3.6 parts by weight of tolylene diisocyanate (manufactured by Mitsui Toatsu Kagaku Kogyo KK, trade name TDI-80) was added at the same temperature, and then to 100 ° C. over 1 hour. The temperature was raised and the reaction was carried out at the same temperature for 4 hours to obtain a toluene solution of urethane-modified rosin ester.

Infrared absorption spectrum analysis was conducted on the obtained solution, and it was confirmed that the isocyanate group had completely disappeared. The solid content concentration of the obtained solution was 59.5.
%, And the hydroxyl value of the urethane-modified rosin ester is 1
It was 0.2.

Next, 100 parts by weight of the above resin solution was charged into a glass container, 7.0 parts by weight of an aqueous solution of sodium dodecylbenzenesulfonate (nonvolatile content: 30%) as an emulsifier, and 50 parts by weight of deionized water were charged, and the mixture was homogenized. Pre-emulsify for 2 minutes with a mixer and 250 with a high pressure homogenizer.
High-pressure emulsification was performed at a pressure of kg / cm ² to obtain a urethane-modified rosin ester emulsion.

Then, 100 parts by weight of the above emulsion was charged into a vacuum distillation apparatus made of glass, and the solvent was removed under reduced pressure at a reduced pressure of 110 mmHg and a temperature of 47 ° C. for 7 hours to adjust the concentration.
An urethane-modified asymmetric rosin glycerin ester emulsion having a solid content concentration of 50.2% was obtained.

Example 2 In Example 1, the raw material rosin derivative was used as the asymmetric asymmetric rosin pentaerythritol ester (manufactured by Harima Chemicals Co., Ltd .: trade name Hariestar DS-110S: acid value 15: hydroxyl value 45). : Softening point 1
Except that the addition amount of tolylene diisocyanate was changed to 6.5 parts by weight and the reaction was carried out for 5 hours in the same manner as in Example 1 to obtain a toluene solution of a urethane-modified rosin ester. The solid concentration of the obtained solution is 60.3.
%, And the hydroxyl value of the urethane-modified rosin ester is 1
It was 4.5.

The solution was further emulsified and desolvated in the same manner as in Example 1 to give a solid content of 50.1.
% Of a urethane-modified asymmetric rosin pentaerythritol ester emulsion was obtained.

Example 3 The toluene solution of the pentaerythritol ester of the urethane-modified asymmetric rosin obtained in the above Example 2 was used, and the emulsifier was an aqueous solution of sodium polyoxyethylene alkyl ether sulfonate (nonvolatile content 26%). Emulsification and desolvation operations were performed in the same manner as in Example 2 except that the amount was changed to 8.1 parts by weight, and the solid content concentration was adjusted to 5
A 0.2% urethane modified asymmetric rosin pentaerythritol ester emulsion was obtained.

Example 4 The rosin derivative used as the raw material in Example 1 was replaced by a pentaerythritol ester of asymmetric asymmetric rosin (produced by Harima Kasei Co., Ltd .: trade name Hariestar DS-90: acid value 18: hydroxyl value 75). : Softening point 90
℃), the addition amount of tolylene diisocyanate is 1
The procedure of Example 1 was repeated, except that the amount was changed to 0.5 part by weight, and the reaction was carried out for 8 hours to obtain a toluene solution of a urethane-modified rosin ester. Solid content concentration of the obtained solution is 61.2%
And the hydroxyl value of the urethane-modified rosin ester is 2
It was 3.5.

Further, the solution was emulsified and desolvated in the same manner as in Example 1 to obtain a solid content concentration of 50.3.
% Of a urethane-modified asymmetric rosin pentaerythritol ester emulsion was obtained.

Example 5 The rosin derivative used as the raw material in Example 1 was prepared by polymerizing a rosin-modified pentaerythritol ester (manufactured by Harima Kasei Co .: trade name Hariestar N-130: acid value 18: hydroxyl value 40: softened). Point 130
Example 1 except that the isocyanate compound was changed to 4.8 parts by weight of hexamethylene diisocyanate.
The reaction was carried out in the same manner as above for 6 hours to obtain a toluene solution of urethane-modified rosin ester. The solid content concentration of the obtained solution was 59.8%, and the hydroxyl value of the urethane-modified rosin ester was 11.5.

Further, the solution was emulsified and desolvated in the same manner as in Example 1 to obtain a solid content concentration of 50.1.
% Of a urethane-modified polymerized rosin-modified pentaerythritol ester emulsion was obtained.

Example 6 The reaction vessel described in Example 1 was charged with 100 parts by weight of rosin alcohol (Rika Hercules Co., Ltd .: trade name Abitol: hydroxyl value 148) and 75 parts by weight of toluene as a solvent, and nitrogen was added. The mixture was stirred while blowing gas and the temperature was raised to 50 ° C. to completely dissolve the rosin ester.

Then, 21.5 parts by weight of tolylene diisocyanate (TDI-80) was added at the same temperature, and then 1
The temperature was raised to 100 ° C. over time, and the reaction was carried out at the same temperature for 5 hours to obtain a toluene solution of urethane-modified rosin alcohol. The solid content concentration of the obtained solution was 58.2%,
The hydroxyl value of the urethane-modified rosin alcohol was 13.8.

Then, the solution was emulsified and desolvated in the same manner as in Example 1 to obtain a urethane-modified rosin alcohol emulsion having a solid content concentration of 50.0%.

(Comparative Example) [Comparative Example 1] A glycerol ester of asymmetric rosin (Hariester DS-90S) 100 was placed in a reaction vessel equipped with a thermometer, a nitrogen introducing tube, a stirrer, a cooling tube and a water draining tube. Part by weight and 70 parts by weight of toluene as a solvent were charged, and the mixture was stirred while blowing nitrogen gas to raise the temperature to 100 ° C.,
The rosin ester was completely dissolved.

Then, the obtained rosin ester solution was emulsified and desolvated in the same manner as in Example 1,
An emulsion of disproportionated rosin glycerin ester with a solids content of 50.2% was obtained.

Comparative Example 2 The same procedure as in Comparative Example 1 was carried out except that the raw material rosin ester was changed to pentaerythritol ester of disproportionated rosin (Hariester DS-110S) in Comparative Example 1, and the solid content was changed. Concentration 50.3%
An asymmetric emulsion of rosin pentaerythritol ester was obtained.

[Comparative Example 3] The same operation as in Comparative Example 2 was repeated except that the emulsifier in Comparative Example 2 was changed to 7.9 parts by weight of an aqueous solution of sodium polyoxyethylene alkyl ether sulfonate (nonvolatile content: 26%). And solids concentration 50.2%
An asymmetric emulsion of rosin pentaerythritol ester was obtained.

[Comparative Example 4] The solid content was the same as in Comparative Example 1 except that the raw material rosin ester was changed to pentaerythritol ester of disproportionated rosin (Hariester DS-90). An emulsion of asymmetrical rosin pentaerythritol ester having a concentration of 50.3% was obtained.

[Comparative Example 5] A solid content concentration of 50 was obtained in the same manner as in Comparative Example 1, except that the raw material rosin ester was changed to polymerized rosin-modified pentaerythritol ester (Hariester N-130). An emulsion of 0.2% polymerized rosin-modified pentaerythritol ester was obtained.

[Comparative Example 6] The same procedure as in Comparative Example 1 was repeated except that the raw material rosin derivative was changed to rosin alcohol (avitol) in Comparative Example 1, and the solid content concentration was 49.8.
% Rosin alcohol emulsion was obtained.

In each of the above comparative examples, the same rosin derivative was used as compared with the corresponding examples described above.
Except for only the operation of reacting the isocyanate compound, the emulsion is dissolved in a solvent and emulsified by the same operation.

(Preparation of Water-based Pressure Sensitive Adhesive Composition) The tackifier obtained in each of the Examples and Comparative Examples was added to 100 parts by weight of the solid content of the emulsion of the acrylic copolymer obtained in Reference Example. Then, the amount shown in Table 1 is added as a solid content, and they are sufficiently stirred and mixed. After that, an aqueous acrylic acid copolymer (manufactured by Nippon Acrylic Chemical Co., Ltd .: trade name Primal ASE-60:
0.6% by weight of solid content) was added, and a small amount of aqueous ammonia was further added, followed by stirring and mixing to adjust the coating viscosity.

(Preparation of Pressure-Sensitive Adhesive Tape Test Piece) Each water-based pressure-sensitive adhesive composition prepared as described above was applied to a thickness of 25
A μ polyester film (trade name: Lumirror, manufactured by Toray Industries, Inc.) was coated with an applicator so that the coating thickness after drying was 25μ, and dried for 3 minutes in a hot air dryer at 105 ° C, and release paper. To produce a pressure-sensitive adhesive tape.

(Physical Property Test) [Adhesiveness] According to JIS Z-0237, the peel strength was measured using a polypropylene plate as an adherend. The test results are shown in g / 25 mm. [Tack] Inclination angle 30 according to JIS Z-0237
Fix the test piece on the slope of ° and put 1/32 on the test piece.
A ~ 32/32 inch steel ball was rolled and the No. of the largest steel ball stopped on the adhesive surface was measured. [Holding power] According to JIS Z-0237, a stainless plate was used as an adherend, and the time until the tape dropped from the adherend was measured under an atmosphere of 80 ° C. The test results are displayed in time.

(Test Results) Table 1 shows the test results.

[0063]

[Table 1]

[0064]

As can be understood from Table 1 and Table 2,
Comparing the corresponding Examples and Comparative Examples, the Examples show that the adhesive strengths are equal or higher, and the tack tends to slightly decrease, but the holding power in a high temperature atmosphere of 80 ° C. is significantly increased. It is improving.

Therefore, according to the present invention, an adhesive composition having excellent holding power especially in a high temperature atmosphere is obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Hamada, Inventor Masao Hamada, No. 4 671 Mizushi, Noguchi-cho, Kakogawa-shi, Hyogo 4 Harima Kasei Co., Ltd. Central Research Laboratory

Claims (5)

[Claims] 1. A solid content of 100 parts by weight of an emulsion containing a poly (meth) acrylic acid ester as a main component,
A water-based adhesive composition, characterized in that 1 to 50 parts by weight of a urethane-modified rosin derivative obtained by reacting a compound having an isocyanate group with a rosin derivative having a hydroxyl group is added. 2. The poly (meth) acrylic acid ester is a polymer having an ester of (meth) acrylic acid and an alkyl alcohol having 1 to 18 carbon atoms as a main component. 1. The water-based adhesive composition according to 1. 3. The polymer comprises at least 80% by weight of at least one of the (meth) acrylic acid alkyl ester,
The water-based adhesive composition according to claim 2, wherein the water-based adhesive composition is a copolymer with at least one vinyl monomer copolymerizable therewith. 4. The rosin derivative is an ester of rosin and a polyhydric alcohol.
Water-based adhesive composition described in 5. The hydroxyl value of the rosin derivative is 10 to 1
The water-based adhesive composition according to claim 1 or 4, wherein the water-based adhesive composition is 80.