JPH0765020B2 - Pressure sensitive adhesive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base resin. More specifically, it relates to a pressure-sensitive adhesive obtained by containing an aromatic hydrocarbon resin having a specific property in an acrylic polymer as a tackifier.

Conventional technology Acrylic pressure-sensitive adhesive using acrylic polymer as base resin is colorless and transparent and has excellent aging resistance.
Widely used for decoration, masking tape, labels, stickers, stickers, and adhesives for interior materials.

Acrylic pressure-sensitive adhesive is generally an acrylic polymer containing a tackifier, the adhesive force according to the purpose, the adhesive force,
An adhesive having properties such as cohesive strength is obtained.

Problems to be Solved by the Invention However, resins such as rosin-based resins and terpene resins are known as tackifiers, but hydrocarbon resins such as petroleum resins are not compatible with the acrylic polymer that is the base polymer. There is a problem that it has not been put to practical use because of poor solubility and poor adhesion.

An object of the present invention is to improve the above-mentioned problems of hydrocarbon resins and to provide a hydrocarbon resin having excellent performance as a tackifier for acrylic pressure-sensitive adhesives.

Means for Solving the Problems According to the present invention, the above problems are related to an acrylic pressure-sensitive adhesive containing an acrylic polymer and a hydrocarbon resin having a hydroxyl value of 40 to 130 and a softening point of 60 to 150 ° C. Will be solved.

The hydrocarbon resin of the present invention is obtained by adding phenols to an aromatic petroleum fraction and / or petroleum fraction having a boiling point in the range of 140 to 240 ° C. and polymerizing with a Friedel-Crafts type catalyst.

Usually, after the polymerization, the catalyst is further decomposed with an alkali, and then unreacted oil and low-polymerization product are separated and removed to be purified and used as the resin of the present invention.

The aromatic petroleum fraction used in the present invention, naphtha, kerosene, a cracked oil obtained in the boiling point in the range of 140 ~ 240 ℃ obtained by pyrolysis such as steam cracking petroleum fractions such as light oil An aromatic petroleum fraction is a heavy oil obtained from coke oven gas and has a boiling point of 140 to 240 ° C.
Is a fraction within the range. Such boiling point 140-240 ℃
The distillate usually contains 35 to 70% by weight of an aromatic olefin having 8 to 10 carbon atoms such as styrene, alkylstyrenes, indene, alkylindenes and coumarone.

Examples of the phenols used in the present invention include phenol, cresol, xylenol, t-butylphenol, nonylphenol and the like. These are 2
You may use it as a mixture of 2 or more types.

The ratio of aromatic petroleum fraction and / or coal fraction (hereinafter referred to as aromatic fraction) and phenols used should be such that the hydroxyl value of the target hydrocarbon resin is within the range of 40 to 130. Blend into. Usually, 5 to 40 parts by weight, preferably 10 to 30 parts by weight of phenols are used per 100 parts by weight of the aromatic fraction.

Next, a Friedel-Crafts type catalyst is added to the mixture of the aromatic fraction and the phenols to cause polymerization.

As the Friedel-Crafts type catalyst, boron trifluoride, aluminum chloride, boron trifluoride phenol complex compound, boron trifluoride dialkyl ether complex compound, etc. are used, and the addition amount is usually 0.05 to 5 wt%, preferably It is 0.1 to 3 wt%. The polymerization time is usually about 10 minutes to 5 hours, and the polymerization temperature is -10 ° C to + 80 ° C.

After the polymerization, the catalyst is decomposed and removed with an alkali such as caustic soda or sodium carbonate, and then the unreacted oil and the low polymer are separated by an operation such as evaporation or distillation to obtain the hydrocarbon resin of the present invention.

Hydrocarbon resin in the present invention has a hydroxyl value of 40 to 130, preferably 50 to 120, a softening point of 60 to 150 ° C, preferably 80 to 13
It is at 0 ° C.

When the hydroxyl value is less than 40, the compatibility with the acrylic polymer is poor and the adhesive property is deteriorated. On the other hand, the hydroxyl value is 130
When it is larger, the compatibility with the acrylic polymer and the adhesive property are good, but the hue of the resin is bad, which is not preferable. It is also not preferable in that the resin yield at the time of production becomes low.

If the softening point of the resin is lower than 60 ° C, the cohesive strength of adhesiveness will be poor,
On the other hand, when the temperature is higher than 150 ° C, the adhesive strength and the adhesive strength are poor.

The pressure-sensitive adhesive of the present invention contains an acrylic polymer and the above-mentioned hydrocarbon resin as a tackifying resin. The mixing ratio of the hydrocarbon resin of the present invention is 3 to 70 parts by weight, preferably 5 to 50 parts by weight based on 100 parts by weight of the acrylic polymer.
Parts by weight.

As the acrylic polymer used in the present invention, all acrylic acid ester polymers conventionally used as a base polymer of an acrylic pressure-sensitive adhesive can be used. For example, all homopolymers of acrylic acid ester, copolymers of different types of acrylic acid ester, copolymers of acrylic acid ester and other copolymerizable ethylenically unsaturated monomer, etc. can be used, It can be appropriately selected depending on the purpose of use. A particularly preferred acrylic polymer has 1 to 1 carbon atoms.
8 is a copolymer of 30% by weight or more of at least one acrylate having an alkyl group and 70% by weight or less of at least one other copolymerizable ethylenically unsaturated monomer. The acrylic ester imparts basic adhesive properties to the acrylic polymer itself, and among them, those having an alkyl group having 4 to 8 carbon atoms are preferable. Specifically, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, sec-butyl acrylate,
Examples thereof include t-butyl acrylate, hexyl ethyl acrylate, octyl acrylate, and 2-ethylhexyl acrylate.

The copolymerizable ethylenically unsaturated monomer is used together with the acrylic acid ester, and by imparting a glass transition point or a polar group, the properties of the acrylic polymer itself can be further made suitable for the intended use. . Such copolymerizable ethylenically unsaturated monomers include, for example, (meth) acrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, monomers containing a carboxyl group such as ethyl maleate, (meth) Monomers containing hydroxyl groups such as 2-hydroxyoxyethyl acrylate, monomers containing amide groups such as (meth) acrylamide, N-methyl (meth) acrylamide, amide groups such as N-methylol (meth) acrylamide and methylol groups And a monomer containing an amino group such as aminoethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate.

Others are vinyl acetate, vinyl ether, styrene, α
-Methylstyrene, vinyltoluene, etc. are examples of copolymerizable unsaturated monomers.

Divinylbenzene, diaryl maleate, diaryl fumarate, ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, etc. It is also possible to use a monomer having two or more ethylenically unsaturated bonds.

The method for producing the acrylic polymer may be any of bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization and the like. The number average molecular weight of the acrylic polymer should be 5,000 or more, but it can be obtained from the adhesive properties of the pressure-sensitive adhesive, especially from the viewpoint of cohesive force.
It is preferably 00 or more, and preferably 200,000 or less in terms of workability.

The pressure-sensitive adhesive of the present invention is produced by blending an acrylic polymer with a hydrocarbon resin having specific properties. Other tackifiers, antioxidants, pigments, etc.
You may add a filler, a plasticizer, a crosslinking agent, etc. Examples of the crosslinking agent include polyvalent metal oxides or hydroxides, epoxy resins, polyisocyanates, methylol condensates, polyamines and polyamides.

The pressure-sensitive adhesive of the present invention can be used in either a solution type or an aqueous emulsion type.

Effects of the Invention According to the present invention, a tackifying resin capable of improving the adhesive properties of an acrylic pressure-sensitive adhesive can be obtained by using an aromatic fraction abundantly obtained from petroleum or coal. It is equal to or higher than the system resin, and its industrial value is very large.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

Reference Example 1 Of the cracked oil fraction obtained by steam cracking of naphtha, 8 parts by weight of phenol was added to 100 parts by weight of a fraction containing 43% by weight of an unsaturated component in a boiling point range of 145 to 190 ° C.
After adding 0.6 parts by weight of boron trifluoride phenol complex compound catalyst and polymerizing at 30 ° C for 3 hours, the catalyst was decomposed with an aqueous solution of caustic soda, washed with water, and unreacted oil and low polymer were distilled off by vacuum distillation. Resin (I) was obtained. The resin yield was 47% by weight, the softening point was 113 ° C., and the hydroxyl value was 54. The hydroxyl value was measured according to the acetic anhydride method described in IEC Anal. Ed 17 , 394 (1945).

Reference example 2 Distillation of tar gas oil obtained from coal tar and boiling range
A distillate of 176 to 190 ° C was obtained. This fraction contained 54% indene and methylindene as unsaturated components and 6.8 coumarone.
%, And 7.6% of other unsaturated components. This fraction 1
Commercially available cresylic acid (phenol 30%, o-
Cresol 10%, m-cresol 25%, p-cresol
15% and xylenol 10% mixture) 12 parts by weight each,
Add 25 parts by weight, add boron trifluoride ether complex compound
After polymerizing at 60 ° C. for 2 hours, the same post-treatment as in Reference Example 1 was carried out to obtain resins (II) and (III). The resin (II) has a yield of 62% by weight, a softening point of 132 ° C. and a hydroxyl value of 75.
II) had a yield of 69% by weight, a softening point of 93 ° C. and a hydroxyl value of 116.

Comparative Example 1 Phenol 1.5 was added to 100 parts by weight of the cracked oil fraction used in Reference Example 1.
Then, 0.6 part by weight of a boron trifluoride phenol complex compound was added, and the mixture was polymerized at 60 ° C. for 2 hours and then treated in the same manner as in Reference Example 1 to obtain a resin (IV). The resin (IV) had a yield of 43% by weight, a softening point of 115 ° C. and a hydroxyl value of 15.

Comparative Example 2 A resin (V) was obtained under the same conditions as in Reference Example 2 except that 6 parts by weight of phenol was added to 100 parts by weight of the fraction used in Reference Example 2 as a raw material. The yield of resin (V) was 58% by weight, the softening point was 156 ° C., and the hydroxyl value was 41.

Example Commercially available acrylic polymer solution (nonvolatile content 40% by weight) 100
Isocyanate curing agent (37.5% by weight of solid content) in parts by weight
And 2.5 parts by weight of each of the tackifying resins obtained in Reference Examples 1 and 2 and Comparative Examples 1 and 2 in solid components of acrylic polymer,
An adhesive sample was prepared by blending parts by weight.

Each of these adhesive samples was coated on a polyester film with an applicator so that the film thickness after drying was 25 to 30 μm, and heat treated at 100 ° C. for 5 minutes to crosslink. Table 1 shows the results of measuring the adhesive force, adhesive force, and cohesive force of the obtained tape. In addition, the results when the commercially available resin is blended and the case where the tackifying resin is not blended are also shown.

The adhesive strength, adhesive strength and cohesive strength were measured by the following methods.

[Adhesive strength] An adhesive tape of 25 mm x 250 mm was prepared, and a craft tape was attached to leave the measuring portion of 100 mm and used as the run-up portion. Using a J-DOW ball rolling device, a steel ball was rolled at a running distance of 100 mm at an angle of 30 degrees, and the highest number of the ball stopped on the adhesive surface was described. Measuring temperature 20 ℃ (JIS Z-0237
Compliant).

[Cohesive strength] Create an adhesive tape with a width of 25 mm and put it on one end of the stainless steel plate with 25
Toyo Seiki Co., Ltd., bonding so that the area of × 25mm touches
The "creep tester" manufactured by the company was used to measure the offset distance of the tape after 24 hours under a load of 1000 g. Measurement temperature 60 ℃ (JIS
According to Z-0237).

[Adhesive strength] Create an adhesive tape with a width of 25 mm, attach it to a polyethylene plate with a length of 125 mm, apply it to an Instron type testing machine "Tensilon UTM-III-100" manufactured by Toyo Pole Dwin, and 300 mm
Peeling was performed 180 degrees at a speed of / min, and the load required for peeling was measured. Measurement temperature 20 ° C (JIS Z-0237 compliant).

Claims (1)

[Claims] 1. A phenolic compound is added to an acrylic polymer and an aromatic petroleum fraction and / or aromatic coal fraction having a boiling point of 140 to 240 ° C. and then polymerized by a Friedel-Crafts type catalyst. Hydroxyl value obtained from 40-130, softening point 60
An acrylic pressure-sensitive adhesive containing a hydrocarbon resin at ~ 150 ° C.