JPH0784581B2 - Removable pressure-sensitive adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a releasable adhesive composition, and more particularly to a pressure sensitive adhesive composition useful as a photo album mount.

(Prior Art) Conventionally, natural rubber latex has been used as a pressure-sensitive adhesive composition for a photo album mount. The natural rubber pressure-sensitive adhesive has good adhesion and peelability to the photo and the press film (album mount cover film).
It has excellent removability, but if it is used for a long time, the pressure-sensitive adhesive discolors or blocking occurs with the photograph, and the pressure-sensitive adhesive migrates and attaches to the back of the photograph and contaminates it. It had a drawback. According to the knowledge of the present inventor, this drawback is that the anchorage of the natural rubber pressure sensitive adhesive to the mount is low, and the natural rubber is aged as a pressure sensitive adhesive due to air, light, temperature, etc. This is due to the deterioration of physical properties.

Japanese Unexamined Patent Publication (Kokai) No. 50-84326 discloses a pressure-sensitive adhesive composition obtained by mixing a natural rubber latex and a pressure-sensitive adhesive acrylic emulsion. Although the above-mentioned drawbacks are alleviated by such a composition, as long as the natural rubber is contained in the component, it still remains as a drawback.

JP-A-57-61075 discloses an easily peelable pressure-sensitive adhesive composition in which silicone oil is mixed with a pressure-sensitive adhesive acrylic emulsion. However, silicone oil is not embedded in acrylic resin,
Since it is simply added, the silicone oil present on the surface of the adhesive layer may migrate to the adherend and contaminate it.

(Problems to be Solved by the Invention) The present inventor has eliminated the natural rubber pressure-sensitive adhesive which causes the drawback of the conventional pressure-sensitive adhesive for album mount, and made a photograph based on the acrylic resin pressure-sensitive adhesive. Excellent practical performance as a pressure-sensitive adhesive for albums, that is, (1) High anchorability on the surface of the album mount.

(2) Do not contaminate the presser film.

(3) No blocking occurs between the photograph and the photograph even after a long time has passed.

(4) The adhesive properties should not change over time.

The present invention has been achieved by obtaining a pressure-sensitive adhesive composition satisfying the above conditions.

[Structure of Invention]

(Means for Solving Problems) That is, the present invention provides a carboxylic acid-containing monomer of 0.5 to 10
An aqueous dispersion obtained by neutralizing 100 parts by weight (solid content) of an emulsion polymer of an acrylic resin, which is inherently viscous, containing wt% in its constituents, with an epoxy group-containing silane compound 0.05 ~ 5.0 parts by weight and 0.05 aziridine compound having two or more aziridinyl groups in one molecule ~
A releasable pressure-sensitive adhesive composition consisting of 5.0 parts by weight.

The acrylic resin in the present invention contains a carboxylic acid-containing monomer in an amount of 0.5 to 10% by weight in its constituent components and has a carbon number of 4 to 1
The main component is (meth) acrylic acid acrylic ester having an alkyl group of 2. Examples of the carboxylic acid-containing monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid. In addition to the above-mentioned monomers, a copolymerizable monomer such as (meth) acrylic acid alkyl ester having an alkyl group having 3 or less carbon atoms, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene can be used in combination.

The acrylic resin of the present invention can be obtained by polymerizing a monomer mixture containing a carboxylic acid-containing monomer by a usual emulsion polymerization method. The obtained emulsion polymer is neutralized with carboxyl groups in the polymer with volatile amines or ammonia.

As the epoxy group-containing silane compound in the present invention,
Methyltri (glycidyloxy) silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxytriethoxysilane, 2- (3,4-epoxycyclohexyl)-
Examples include ethyltrimethoxysilane.

The silane compound is used in an amount of 0.05 to 5.0 parts by weight, preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the solid content of the acrylic resin. If the above value is less than 0.05 parts by weight, not only the anchoring property to the album mount but also the re-peeling property becomes poor.

The silane compound may be added to and mixed with the aqueous dispersion obtained by neutralizing the volatile amine or ammonia of the emulsion polymer of the acrylic resin.

The aziridine compound in the present invention has an aziridinyl group in one molecule. A compound having two or more (where R is H or a lower alkyl group) and solid at room temperature and insoluble in water is preferably used. Examples of such an aziridine compound include:
1,6-hexamethylenediethyleneurea, 1,5-pentamethylenediethyleneurea, diphenylmethane-bis-4,4-
Examples include diethylene urea and 2,4-diethylene urea toluidine.

The blending amount of the aziridine compound is 0.05 to 5.0 parts by weight, preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the acrylic resin. If the above value is less than 0.05 parts by weight, the cohesive force of the acrylic resin may be insufficient, and the pressure-sensitive adhesive may transfer to the adherend.
If the holding film is contaminated or if the photo is stuck for a long time, blocking may occur between the backing paper and the photo. If it is more than 5.0 parts by weight, the effect cannot be obtained simply by blending it and it is economical. Is not preferable.

The pressure-sensitive adhesive composition of the present invention is used as a one-pack type in which an epoxy group-containing silane compound and an aziridine compound are mixed with an aqueous dispersion obtained by neutralizing an acrylic resin emulsion polymer with a volatile amine or ammonia. You can
The order of compounding is not particularly limited. In the composition, the silane compound and the aziridine compound do not react with the acrylic resin and maintain good storage stability in a solution state. It is considered that this is because the carboxyl group which is a reactive group in the acrylic resin is blocked by the volatile amine or ammonia. When the pressure-sensitive adhesive composition of the present invention is coated on a substrate and dried under normal drying conditions, amines or ammonia that have blocked the carboxyl group are released and scattered,
A crosslinking reaction occurs.

The pressure-sensitive adhesive composition of the present invention may contain additives such as pigments, plasticizers, tackifiers, protective colloid agents, antifoaming agents, antiseptic agents and antifungal agents.

The present invention will be described below with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

Examples Example 1 A monomer mixture consisting of 60 parts of 2-ethylhexyl acrylate, 30 parts of n-butyl acrylate and 4.5 parts of acrylic acid, 2.5 parts of anionic surfactant and 2.5 parts of nonionic surfactant was used. , Ammonium persulfate 0.5 in 100 parts of water
An acrylic resin emulsion was obtained by emulsion polymerization using the part as a catalyst. Solid content of this acrylic resin emulsion
To 100 parts, 0.1 part of methyltri (glycidyloxy) silane was mixed, and after stirring, diphenylmethane-bis-
A 10% aqueous dispersion of 4,4-N, N-diethylene urea was mixed in an amount of 0.5 part as a solid content to obtain a pressure-sensitive adhesive composition.

Comparative Example 1 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that only the silane compound was removed.

Comparative Example 2 A pressure sensitive adhesive composition was obtained in the same manner as in Example except that only the aziridine compound was removed.

Example 2 70 parts of 2-ethylhexyl acrylate, 15 vinyl acetate
Parts, methyl methacrylate 7.5 parts, acrylic acid 2.0 parts monomer mixture, using anionic surfactant 2.5 parts, nonionic surfactant 2.5 parts, 0.5 parts ammonium persulfate as a catalyst in 100 parts water An acrylic resin emulsion was obtained by emulsion polymerization. 0.05 part of 3-glycidoxypropyltrimethoxysilane was mixed with 100 parts of the solid content of this acrylic resin emulsion, and after stirring, 10% of diphenylmethane-bis-4,4-N, N-diethyleneurea was added.
A solid content of the aqueous dispersion was mixed with 0.25 part to obtain a pressure-sensitive adhesive composition.

Example 3 A monomer mixture consisting of 70 parts of 2-ethylhexyl acrylate, 28 parts of methyl methacrylate and 2.0 parts of acrylic acid was used in an amount of 2.0 parts of anionic surfactant and 1.0 part of nonionic surfactant in 100 parts of water. Ammonium persulfate 0.5
An acrylic resin emulsion was obtained by emulsion polymerization using parts of the catalyst. Solid content of this acrylic resin emulsion
0.5 part of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was mixed with 100 parts, and after stirring, 10% aqueous dispersion of toluene-bis-2,4-N, N-diethyleneurea Was mixed in a solid content of 1.0 part to obtain a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition obtained in each of Examples 1 to 3 and Comparative Examples 1 to 2 was applied to the surface of an album mount so as to have a thickness of 5 to 10 μm (when dried), and after drying, a pressing film was applied to the surface of the mount. As a result, stretched polypropylene was attached. Then, the peeling force (g / 135 mm) of the pressing film was tested under various conditions, and shown in Table 1. Next, an album suitability test such as stain resistance to the presser film, anchorage to the mount, blocking property, etc. was performed, 3
A graded evaluation (○ ... good: Δ ... somewhat good: × ... bad) was performed and shown in Table 2.

Further, the same test was conducted on a commercially available album mount using a natural rubber pressure-sensitive adhesive, and shown as Comparative Example 3.

In Table 1, the peeling force of the product of the present invention is lower than that of the commercial product using the natural rubber-based pressure-sensitive adhesive of Comparative Example 3, but there is sufficient peeling power for the album mount, and in practical use. No problem. Rather, the natural rubber pressure-sensitive adhesive is deteriorated by environmental temperature, ultraviolet rays, etc., so that the peeling force after treatment is remarkably increased as compared with the product of the present invention.

〔The invention's effect〕

The releasable pressure-sensitive adhesive composition of the present invention has excellent anchoring properties to a substrate such as an album mount, and has almost no adhesive property, particularly removability even when stored for a long time in an environment such as environmental temperature or ultraviolet ray. A pressure sensitive adhesive that does not degrade can be formed. Therefore, even if the adherend such as a photograph is attached for a long period of time and then peeled off, the phenomenon such as blocking does not occur between the mount and the adherend.

Further, since the one-pack type adhesive composition containing a curing agent also has good storage stability, there is no need to add a curing agent immediately before coating, and thus the industrial utility is great.

Claims (1)

[Claims] 1. A 100 parts by weight (solid content) of an inherently tacky acrylic resin emulsion polymer containing 0.5 to 10% by weight of a carboxylic acid-containing monomer in its constituents is neutralized with volatile amines or ammonia. Removable pressure-sensitive adhesive composition comprising the following aqueous dispersion, 0.05 to 5.0 parts by weight of an epoxy group-containing silane compound, and 0.05 to 5.0 parts by weight of an aziridine compound having two or more aziridinyl groups in one molecule.