JP3347190B2 - Functional acrylic adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer component having a function of absorbing ultraviolet light in a molecule, which makes it possible to use it in pressure-sensitive adhesive tapes and sheets used continuously in places exposed to ultraviolet light such as outdoors. The present invention relates to a pressure-sensitive adhesive composition containing:

[0002]

2. Description of the Related Art In recent years, pressure-sensitive adhesive tapes and sheets have been used in various applications because of their convenience, and the applications have been expanding year by year. Particularly in recent years, applications have been increasing not only indoors but also outdoors, which is a harsh environment exposed to sunlight. In general, the spectrum of sunlight has a maximum peak at 500 nanometers and is continuously distributed in a range of 300 to 2,000 nanometers. Of these, so-called ultraviolet rays of 400 nm or less are factors that cause a chemical reaction or the like, and are known to have various effects on chemical substances.

[0003] In applications where an adhesive is used, curing tapes and protective sheets used in construction sites and general outdoor advertising panels and posters are directly exposed to ultraviolet rays from sunlight, so that they are relatively weather resistant. Acrylic adhesives that are considered good are used. However, in the case of a conventional general acrylic pressure-sensitive adhesive, the pressure-sensitive adhesive tape or its processed product is subjected to the decomposition of the main chain of the pressure-sensitive adhesive by the energy of ultraviolet rays or the repolymerization reaction of unreacted monomers left in the pressure-sensitive adhesive. Defects such as causing significant adhesive residue when peeling, making this removal work difficult, danger of falling off from the adherend due to a decrease in adhesive strength, and a decrease in commercial value due to yellowing due to an increase in conjugated systems There was.

In order to avoid such disadvantages caused by ultraviolet rays,
As a method of reducing the unreacted monomer in the adhesive, use of a polymerization method such as a method for improving the reaction efficiency or a low-temperature polymerization,
Various attempts have been made to examine a washing method for removing unreacted monomers, but it is impossible to eliminate unreacted monomers during polymerization, and a large number of steps and costs are required for the washing method. Therefore, none of these methods is a definitive solution at present.

On the other hand, as a method of preventing the main chain from being cut by ultraviolet rays, for example, an ultraviolet absorbent such as a benzophenone type, a benzotriazole type, or a phenyl salicylate type, which cuts ultraviolet rays of 400 nm or less, is mixed in the adhesive. Methods have been proposed and put into practical use, but due to the stability of the absorbent itself and compatibility with the adhesive, the absorbent mixed during use bleeds and loses its adhesive properties, In addition, the ultraviolet absorption effect itself was lost due to decomposition or decomposition, so that a definitive effect on imparting ultraviolet resistance could not be given. Further, a method of blocking ultraviolet rays by mixing a metal powder or carbon black has also been proposed, but this method has no effect on imparting the ultraviolet light resistance of the adhesive itself, and is limited in applications such as loss of transparency. There were disadvantages.

[0006]

SUMMARY OF THE INVENTION In order to prevent the above-mentioned deterioration of the pressure-sensitive adhesive caused by ultraviolet rays having a wavelength of 400 nm or less, the present invention exhibits good pressure-sensitive adhesive properties for ordinary use and has a long time. It is an object of the present invention to provide a pressure-sensitive adhesive having stable resistance to ultraviolet light for a long time without any change in the pressure-sensitive adhesive even during use, no disadvantage such as adhesive residue even after use. .

Further, the present invention provides a novel acrylic pressure-sensitive adhesive having a UV-absorbing function in a pressure-sensitive adhesive polymer, which is free from bleeding and deterioration, has a stable pressure-sensitive adhesive property against UV light and the durability of the pressure-sensitive adhesive itself. To providing an agent composition.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a novel and effective UV-absorbing function in a pressure-sensitive adhesive polymer for the purpose of preventing the above-mentioned disadvantages. It is characterized in that a copolymer obtained by copolymerizing a -6-heptene-1,3-dione-based substance with an acrylic ester and an α-monoolefincarboxylic acid is contained as a pressure-sensitive adhesive polymer component. . By containing the copolymer as a pressure-sensitive adhesive polymer component, novel ultraviolet absorption without bleeding caused by dispersing and mixing a normal ultraviolet absorber in the pressure-sensitive adhesive and without deactivating the ultraviolet absorption function A pressure-sensitive adhesive having a function inside the adhesive is obtained.

In the pressure-sensitive adhesive composition of the present invention, 1 is used for producing the above copolymer having an ultraviolet absorbing function.
-Aryl-6-heptene-1,3-dione is a compound obtained by a type II cleavage reaction of 2-aroylcyclohexanone. Specifically, the aryl group is a phenyl group or a substituent having a halogen, especially chlorine. Alternatively, 1-aryl-6-heptene-1,3-dione having a substituted phenyl group which is a lower alkyl group having 1 to 5 carbon atoms can be used. These compounds exhibit an effective ultraviolet absorbing effect when used in the production of the ternary copolymer as a monomer at a compounding ratio of 1 to 10 parts by weight.
When the amount is less than 1 part by weight, the ultraviolet absorbing effect is not clearly exhibited, and when the amount is more than 10 parts by weight, there is a disadvantage that the cohesiveness of the pressure-sensitive adhesive as a copolymer is inhibited.

Acrylic ester or methacrylic ester, which is the second component of the monomer used in the production of the copolymer, is a component which serves as a skeleton of the copolymer as an adhesive and usually has 2 to 8 carbon atoms. It consists of an ester of acrylic acid or methacrylic acid of a straight-chain alcohol. Generally, two or three kinds of the ester monomers are mixed to form 35 to 80
It is blended with another monomer component in a ratio of parts by weight and used for producing a copolymer. When the amount of the ester monomer is 35 parts by weight or less, the copolymer becomes hard and does not exhibit appropriate viscoelasticity as an adhesive, or the control of copolymerization may become impossible, or 80 parts by weight or more. In this case, the cohesiveness is extremely insufficient, and the properties as an adhesive cannot be exhibited.

The α-monoolefin carboxylic acid, which is the third component of the monomer used in the production of the copolymer, includes:
Not only monocarboxylic acids such as acrylic acid, methacrylic acid, vinyl acetic acid and allyl acetic acid but also dicarboxylic acids such as itaconic acid can be used. The α-monoolefin carboxylic acid is blended in the range of 3 to 20 parts by weight and used for producing a copolymer. If the amount is less than 3 parts by weight, the reactivity with the curing agent added later is insufficient, and the cohesive strength as an adhesive tape is insufficient. If the amount is more than 20 parts by weight, the copolymer does not have an appropriate viscosity, and The polymerization and control itself become difficult, which hinders the production of adhesives and the production of adhesive tapes.

The copolymer of the present invention is prepared by mixing 100 parts by weight of a reaction raw material obtained by mixing three components of a monomer in the above mixing ratio with 80 to 80 parts by weight.
It is produced by dissolving in 150 parts by weight of an organic solvent such as toluene or ethyl acetate or dispersing in water and adding a polymerization initiator such as benzoyl peroxide or azobisisobutylnitrile to copolymerize.

The copolymer obtained by the above copolymerization reaction is a transparent and viscous liquid having a weight-average molecular weight of 50,000 to 500,000. Used after adjustment. In preparing the pressure-sensitive pressure-sensitive adhesive composition of the present invention, the above-mentioned copolymer is cured with various additives usually used, for example, various metal chelate complexes, polyamines, diamines, polyisocyanates, epoxy resins, and the like. Agents and various tackifying resins can be added.

The pressure-sensitive adhesive composition thus compounded includes films of polyethylene, polyvinyl chloride, polypropylene, polyester, polyamide, polyimide, acetate, etc., and cloths of fibers such as cotton, cloth, glass, acetate, polyester, acrylic, etc. Metal foils such as aluminum, copper, iron, non-woven fabrics such as polyester and polypropylene, Japanese paper,
It can be applied to various substrates such as paper such as crepe and flat with a roll coater, reverse coater, dip coater, etc., dried, wound up to a predetermined length and cut to a predetermined width to obtain an adhesive tape. .

The copolymer of the present invention is itself a pressure-sensitive adhesive component, and further has an ultraviolet absorbing function contained in the polymer. This is advantageous in that it is less susceptible to interference and therefore has a wider range of use.

The pressure-sensitive adhesive tape using the pressure-sensitive adhesive of the present invention comprises:
This adhesive is stable even when exposed to ultraviolet rays from either the substrate surface side or the adhesive surface side.For example, various curing of posters and construction sites used outdoors, protective sheets and living bodies For applications that are exposed to ultraviolet light through substrates such as adhesive sheets, and when used to protect window glass, etc.
It can be effectively used for all applications including direct exposure to ultraviolet rays from the adhesive surface.

These adhesive tapes are used not only for applications in which the tapes are used alone, but also for applications in which various materials are exposed to ultraviolet rays, such as automobiles and other transport equipment, toys, and stationery, in combination with other materials by punching or laminating. Is done. Adhesive tapes used for such purposes do not remain on the adherend even if they are peeled off inadvertently when the purpose of the adhesive tape has been completed and it needs to be peeled off. Moreover, there is no danger such as falling off of the adhesive tape and the processed product due to loss of the adhesive property. On the other hand, it can be used as a transparent and stable masking sheet in an edging application of an electronic component using a technique such as exposure as an artificial ultraviolet application field.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

【Example】

Example 1 75 parts by weight of butyl acrylate, 5 parts by weight of ethyl acrylate, and 20 parts by weight of acrylic acid were mixed with 1.5 parts by weight of 1-phenyl-6-heptene-1,3-dione. Mixed solvent of ethyl ester and toluene 1
Azobisisobutylnitrile at a concentration of 1.5% in 100 parts by weight was used as a radical initiator in a reactor equipped with a condenser.
C., and copolymerized for 3 hours. The obtained copolymer was a colorless and transparent viscous substance having a weight-average molecular weight of about 75,000. This was washed five times with alcohol and ethyl acetate alternately, and the ultraviolet-visible absorption spectrum was measured to be 313 nm. It was a sticky polymer having an ultraviolet absorption function in the molecule having the maximum absorption in the meter.

The concentration of the copolymer is adjusted to 35% by weight with toluene, and 1.2% of tolylene diisocyanate is added to the solid copolymer to form an adhesive solution. A 25 μm thick single-sided discharge-treated transparent polyethylene film was coated with a roll coater to a total thickness of 50 μm, dried at 85 ° C. for 3 minutes, and left at room temperature for 1 week to produce a pressure-sensitive adhesive tape. . The peeling adhesive force of this adhesive tape was 1200 g / 25 mm width when measuring 180 ° peeling force at a peeling speed of 300 mm / min against a stainless steel plate, and the tack was obtained by a ball rolling method at an angle of 10 °. 25. Further, the holding force when the static load was set to 500 g with an adhesive area of 10 mm square and the deviation was only 0.2 mm even in a 70 ° C. atmosphere, showing good adhesive properties. The 180 ° peeling force, tack and holding force are J
The test was carried out according to IS-Z-0237 8.3.1 "180 degree peeling method", 12 "tack" and 11 "holding force" test methods.

In order to demonstrate the UV resistance of the pressure-sensitive adhesive, the pressure-sensitive adhesive tape was stuck to a stainless steel plate and a Pyrex glass plate, and the stainless steel plate sample was exposed from the polyethylene substrate surface, and the Pyrex plate sample was exposed to the pressure-sensitive adhesive surface. 7 days each for outdoor exposure and 2000 for sunshine weather meter
The results of examining the appearance, adhesive strength, and adhesive residue after a long time were all good as shown in Table 1.

Example 2 1 part by weight of 1-phenyl-6-heptene-1,3-dione was mixed with 50 parts by weight of 2-ethylhexyl acrylate, 25 parts by weight of butyl acrylate and 15 parts by weight of acrylic acid, and 50 parts by weight of toluene and The copolymer was copolymerized with 50 parts by weight of ethyl acetate and 1% of benzoyl peroxide under the same conditions as in Example 1. The obtained copolymer has a weight average molecular weight of about 90,
000 was a transparent viscous solution. The UV-visible absorption spectrum after washing in the same manner as in Example 1 had a maximum absorption at 315 nm.

A pressure-sensitive adhesive tape was prepared from this pressure-sensitive adhesive composition on the same substrate as in Example 1 by the same method, and the results of measuring the pressure-sensitive adhesive properties and UV resistance are shown in Table 1. From Table 1,
This copolymer composition exhibited good adhesive properties and UV resistance.

COMPARATIVE EXAMPLE In order to compare the effects of the present invention, a composition was prepared by removing 1-phenyl-6-heptene-1,3-dione from the composition of Example 1 and using a solvent and a radical polymerization initiator. Copolymerization was carried out under the same conditions as in Example-1. The obtained copolymer composition was a colorless and transparent viscous substance having a weight-average molecular weight of about 95,000. The ultraviolet-visible absorption spectrum after washing with the solvent showed no effective absorption in the ultraviolet.

An adhesive tape was prepared from the polymer on the same substrate as in Example 1 in the same manner, and the same items of adhesive properties and UV resistance were measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the 1-aryl-6-heptene-1,3-dione-based component, 1-phenyl-6-heptene-1,3-dione, was coated with an adhesive containing no copolymerization component. The tape did not have sufficient UV resistance, demonstrating the effectiveness of the present invention.

[0025]

[Table 1]

[0026]

As described above, the present invention relates to 1-aryl-
The 6-heptene-1,3-dione-based component works on the copolymerization system of the pressure-sensitive adhesive to effectively absorb ultraviolet light, and has stable adhesive properties and paste even when exposed directly to ultraviolet light, such as in outdoor exposure applications. It was possible to obtain a pressure-sensitive adhesive composition having extremely effective ultraviolet light resistance without remaining or discoloration.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09J 133/08 C09J 7/02 C09J 9/00

Claims (1)

(57) [Claims] 1. 1-aryl-6-heptene-1,3-
A ternary monomer consisting of 1 to 10 parts by weight of dione, 35 to 80 parts by weight of an acrylate and / or methacrylate, and 3 to 20 parts by weight of an α-monoolefin carboxylic acid in an organic solvent or an aqueous solvent A pressure-sensitive adhesive composition comprising a copolymer having in its molecule a function of efficiently absorbing ultraviolet light having a wavelength of 400 nm or less, which is obtained by radical copolymerization in the above.