JPS587470A - Adhesive composition - Google Patents

Abstract

PURPOSE:A composition that is made by adding a polyisocyanate to a specific acrylic copolymer, thus being suitably used as a releasable adhesive which has shortened assembly and heat-aging times and adhesive properties of high stability with time. CONSTITUTION:The objective composition is prepared by adding 0.2-3wt%, based on component B, of (A) a polyisocyanate such as tolylene diisocyanate to (B) a copolymer consisting of more than 50wt% alkyl acrylate (alkyl is of 4-8 carbon atoms) such as n-butyl acrylate, 0.3-10% hydroxyl-containing monomer such as 2-hydroxyethyl acrylate, 0.1-2% monomer containing phosphoric or phosphorous ester groups such as mono(2-hydroxyethyl acrylate)acid phosphate and less than 30% vinyl monomer such as vinyl acetate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acrylic polymer-based adhesive composition which also has good stability of adhesive properties over time.

Adhesive compositions in which a polyisocyanate compound is blended as a crosslinking agent with an acrylic copolymer containing a monomer component containing a number of water groups, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, are well known and can be used as general adhesive products. It is expected that it will have adhesive properties that are effective as a re-accumulator adhesive. However, this adhesive physical property is also affected by aging at room temperature for 5 to 7 days after applying the above adhesive composition to a substrate.
Since it will not develop unless it is aged for 24 to 8 hours under heating at ~70°C, the base material after applying the adhesive is slit,
This base material must not be allowed to accumulate in the factory for a long time before being subjected to secondary processing such as cutting and punching, and its physical properties change significantly over time due to slow crosslinking, making it undesirable as a removable adhesive. There were disadvantages such as:

However, as a result of intensive research by the present inventors, when using a copolymer of a specific composition containing a hydroxyl group-containing monomer and a phosphate group- or phosphite group-containing monomer as an acrylic copolymer, When a composition containing a polyisocyanate compound blended with the copolymer is applied to a substrate, the aging time is significantly shortened, resulting in improved productivity and a reduction in the number of deposits, and physical properties due to rapid crosslinking. The present inventors have discovered that the adhesive has excellent effects such as good stability over time, is suitable as a removable adhesive, and has excellent physical properties, leading to the completion of the present invention.

The adhesive composition of the present invention is formed by blending a polyisocyanate compound (B) with a copolymer (mu) having the following composition.

The main component constituting the copolymer (mu) is an alkyl acrylate having an alkyl group of 4 to 8 carbon atoms. This component must be present in an amount of 50% by weight or more, and if it is less than 50% by weight, sufficient adhesiveness cannot be obtained. Examples of the alkyl acrylate include 1-butyl acrylate, [n-octyl acrylate, 2-ethylhexyl acrylate, etc.] It is particularly preferable to use n-butyl acrylate, 2-ethylhexyl acrylate, or both. .

The copolymer (Al must contain a hydroxyl group-containing monomer. This component is a component that participates in the crosslinking reaction with the polyisocyanate compound, and its content is from 0.1 to
It is set within the range of 20% by weight, preferably from O,S to 10% by weight. If it is less than 0.1% by weight, sufficient crosslinking properties (creep properties) cannot be obtained, while if it exceeds 20% by weight, the copolymer becomes hard and cannot provide sufficient adhesiveness. Darkening components include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and acrylic #! 3-chloro-2-hydroxyglobil, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 6-methacrylate
Examples include hydroxypropyl and 3-chloro-2-hydroxypropyl methacrylate.

The copolymer (A) is 0.01 to 5% by weight, preferably 0.01 to 5% by weight.
It must contain 1 to 2 parts by weight of phosphate or phosphite group-containing monomer. This component itself participates in the reaction with the polyisocyanate compound, and is also presumed to be effective in promoting the reaction between the hydroxyl group introduced by the hydroxyl group-containing monomer and the isocyanate group of the polyisocyanate compound. It is also thought to have favorable effects in terms of adhesive properties. If this component is less than 0.01 weight, it lacks the improvement effect, while if it exceeds 5 weight, it causes gelation of the adhesive solution, which becomes a practical problem.

Such components include mono(2-hydroxyethyl acrylate) acid phosphate, mono(2-hydroxyethyl methacrylate) acid phosphate, and mono(2-hydroxyethyl methacrylate) acid phosphate.
2-hydroxypropyl acrylate) acid phosphate, mono(2-hydroxypropyl methacrylate) acid phosphate, mono(3-hydroxypropyl acrylate) acid phosphate, mono(6-hydroxypropyl methacrylate) acid phosphate, mono(!1-chloro2- Hydroxyglobil acrylate) acid phosphate, mono(3-chloro-
Examples include 2-hydroxypropyl methacrylate) acid phosphate, allyl alcohol acid phosphate, mono(2-hydroxyethyl acrylate) acid phosphite, and mono(2-hydroxyethyl methacrylate) acid phosphite.

In addition, the copolymer (mu) may contain other vinyl monomers copolymerizable with the above-mentioned components in an amount of up to 49.9 parts by weight or less, usually 30 parts by weight or less. Such vinyl monomers include vinyl esters such as vinyl acetate, probion late vinyl, saturated branched fatty acid vinyl, late acrylic esters having an alkyl group of 1 to 6 or 9 or more, alkyl methacrylates having an alkyl group of 1 to 8, Style/
, monocarboxylic acids such as vinyltoluene, acrylonitrile, methacrylaterile, acrylic acid, methacrylic acid, and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid, and itacone, or their monoalkyl esters and dialkyl esters, vinyl chloride, vinyl ether, etc. can be opened.

The above-mentioned copolymer (A) can be obtained by any polymerization method such as bath polymerization or bulk polymerization, or usually by Ti bath withdrawal polymerization method.

The above copolymer (M) contains a polyisocyanate compound (B
) is added. Examples of the polyisocyanate compound (B) include tolylene diisocyanate or its hydride or its adduct with trimethylolpropane, triphenylmethane triincyanate, methylene bis-diphenyl incyanate or hydride, hexamethylene diisocyanate, Xylene diisocyanate, 4.4
'-Dicyclohexylmethane diisocyanate or a polymer thereof having two or more incyanate groups in the molecule is used.

The blending amount of the polyisocyanate compound (Bl) is a carboxyisocyanate compound (EDA) which is effective in maintaining the balance of the adhesive properties such as the adhesive force, cohesive force, and tackiness of the above copolymer (mu). 0 for 1 combined fAl
．． 1-5% by weight, especially 0.2-3! It is appropriate to set it to fi%.

□The composition of the present invention may also contain other tackifiers, fillers, colorants, etc.

The pressure-sensitive adhesive composition of the present invention is applied to the surface of any base material such as plastic film, sheet, tape, board, paper, kneaded cloth, non-woven fabric, etc. in a layered, mesh-like, dot-like, etc. form.

The adhesive composition of the present invention can be used for sealing envelopes and bags, adhesive sheets, films, tapes, labels, sign boards, stickers, etc.
1. Suitable for use in applications such as foams.

Next, the pressure-sensitive adhesive composition of the present invention will be further explained with reference to examples. Hereinafter, "parts" and "%" are expressed on a weight basis.

Example 1 960 parts of n-butyl acrylate, 20 parts of vinyl acetate, 50 parts of 2-hydroxyethyl methacrylate and mono(2-
Hydroxyethyl methacrylate) acid phosphate was solution polymerized by a conventional method in an ethyl acetate solvent using an azobisisobutyronitrile catalyst to obtain a resin concentration of 40.
．． 7, solution viscosity [5500 cps (25°C)] polymer 5it-obtained*.

To 100 parts of this polymer solution, 7ssN & (Coronet manufactured by Nippon Polyurethane Industries Co., Ltd.) L) 0 of an adduct of tolylene diincyanate and trimethylolpropane was added.
．． A mixture of 5 parts was applied onto a 25F thick polyester film so that the coating thickness after drying was 20 to 25P, and dried at 100°C for 2 minutes to prepare a pressure-sensitive adhesive sheet.

After leaving this adhesive sheet at 20°C for 24 hours,
-Z-1528, the normal adhesive force (180° peeling method) and normal holding force were measured.
5 parts 5 g/251I11 Normal state holding power = 24 hours non-creep result was obtained.

Furthermore, after leaving this adhesive sheet at 50℃ for 7 days, the normal adhesive strength and normal holding power were measured again.
333g725m Steady state crab 24 hour non-creep results were obtained.

Here, normal holding power, 24-hour non-creep is a characteristic value that can sufficiently withstand secondary processing of adhesive products, and the fact that there is little change in properties after treatment at 50°C for 7 days indicates stability of physical properties over time, and removable type Suitable as an adhesive.

Control Example A polymer solution was obtained in the same manner as in Example 1 except that only the use of mono(2-hydroxyethyl methacrylate) acid phosphate was omitted, and Coronate L was blended therein as in Example 1. The result is normal sticky crab 1820g/25
The physical properties after further treatment at 50° C. for 7 days were non-creep for 24 hours (463 g/25 mm) for 24 hours. This normal holding power of 0.2 hours is insufficient for secondary processing of the adhesive product, and the properties deteriorate significantly after being treated at 50° C. for 7 days, indicating concerns about the stability of the adhesive product over time.

Examples 2 to 4 Adhesive compositions were prepared by blending a polyisocyanate compound with an acrylic copolymer having the following composition, and their performance was examined in the same manner as in Example 1.

Example 2 2 parts of Coronate L was blended with 100 parts of an ethyl acetate solution of a copolymer with a resin concentration of 111% and 39.4%. Composition Example 4: 100 parts of ethyl acetate solution of a good g copolymer with a resin content of 4. A composition eyelid containing 1 part of Pan Adduct 7518 liquid (Takene D-102, manufactured by Takeda Pharmaceutical Co., Ltd.).

The results are shown in the table below.

Claims (1)

[Claims:] An adhesive composition comprising a copolymer (M) having the following composition and a polyisocyanate compound (B). 2. The composition according to claim 1, wherein the amount of the polyisocyanate compound (B) is 0.1 to 5% by weight based on the copolymer (M).