JPH0133516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adhesive with good removability, and more specifically, even when it is repeatedly attached and peeled off from an adherend, This invention relates to a removable adhesive that does not leave adhesive microparticles on its surface.

[Prior Art] Removable adhesive tapes or sheets using adhesive fine particles as constituent elements are already known, but in conventional removable adhesive tapes, etc.・If peeling is performed,
There was a problem in that the fine particles of the adhesive component remained on the adherend. This problem was noticeable when the adherend was diazocopy paper.

Therefore, in order to solve this problem, we have developed a removable adhesive tape that uses a binder in an amount of about 1/2 to 1/5 of the weight of the adhesive ball to fix the microparticles on the base material. etc. are known (for example,
West German Patent No. 2417312, Utility Model Application No. 1983-60661
(See Japanese Utility Model Publication No. 55-42881).

However, even when a binder is used in this way, the adhesion of microparticles is not sufficient;
When rapid peeling was performed, there was still a problem that fine particles remained on the adherend.

Furthermore, in order to more firmly adhere microparticles to a base material, a method of using an adhesive such as an acrylic emulsion type adhesive as a binder has been considered (see US Pat. No. 3,857,731).

However, even with this method, the adhesion of the microparticles is still insufficient, and a new problem has arisen in that not only the microparticles but also the adhesive used as a binder remains on the adherend.

There is also an invention in which adhesive microparticles in the shape of a semicircular sphere are adhered onto an undercoat layer formed on a base material without using a binder (Utility Model Publication No. 57-
(See Publication No. 57394).

However, in this invention, the adhesive microparticles are limited to a substantially hemispherical shape, and are always fixed to the substrate with the curved surface facing outward, that is, with the contact area between the substrate and the microparticles being larger. It has become necessary to

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problem, that is, when the adherend is repeatedly pasted and peeled, adhesive microparticles remain on the surface of the adherend. This was done in an attempt to solve the problem.

[Means for Solving the Problems] The present inventors conducted intensive research to solve the above problems, and found that conventionally, removable adhesive bodies using adhesive microparticles do not have the above-mentioned problems. The microparticles were fixed onto the substrate by the action of a binder or by a method of increasing the contact area between the undercoat layer and the microparticles (for example, see the aforementioned Japanese Utility Model Publication No. 57-57394). By using an undercoat layer that can specifically bind to adhesive microparticles, it can be applied without using a binder.
Or even if the contact area is extremely small,
The inventors have discovered that it is possible to more firmly bond the base material and the adhesive microparticles, and have completed the present invention.

That is, the removable adhesive of the present invention contains 35 to 15% by weight of vinyl chloride-vinyl acetate-vinyl acetate resin and 65 to 85% by weight of an inorganic pigment on at least one surface of the base material.
It is characterized in that a plurality of adhesive microparticles are attached via an undercoat layer consisting of % by weight.

The undercoat layer, which is a component of the adhesive body, is composed of an undercoat made of vinyl chloride-vinyl acetate resin and an inorganic pigment.

The glass transition temperature of vinyl chloride-vinyl acetate resin, which is a component of the undercoat, is usually 50
℃ or higher and a polymerization degree of 100 or higher, preferably 300 or higher. In addition, this resin is made of vinyl chloride 85-98
% by weight and 15-2% by weight of vinyl acetate. In addition, 0 to 10% by weight of polyvinyl alcohol can also be contained.

In addition, examples of inorganic pigments include zinc white, titanium white,
Examples include silica, calcium carbonate, clay, white lead, and magnesium oxide, and one or more of these can be used.

The blending ratio of resin and inorganic pigment in the primer is 15 to 35% by weight/85 to 65% by weight, preferably 20% by weight.
-30% by weight/80-70% by weight. If the amount of resin blended is less than 15% by weight, a part of the pigment will not mix with the resin and a part will be made of only pigment, which will not only make it impossible to obtain a uniform system as an undercoat, but also cause a significant decrease in strength and It may peel off when scratched or bent. Moreover, if the content exceeds 35% by weight, the anchoring properties of the adhesive microparticles will deteriorate and detachment of the microparticles will occur.

Furthermore, if necessary, a water resistance agent, a stabilizer, a barrier property improver, an antiblocking agent, a dye, etc. may be added to the undercoat within a range that does not impair the performance.

The undercoat layer is made by adding an undercoat into an organic solvent,
It can be formed by kneading and dissolving the mixture and then applying it to at least one surface of the base material.

Examples of the organic solvent used here include esters such as ethyl acetate and butyl acetate. In addition, these esters include alcohols such as methyl alcohol and butyl alcohol, ketones such as acetone and methyl ethyl ketone, aliphatic and aromatic hydrocarbons such as n-hexane, cyclohexane, heptane, mineral spirits, toluene, and xylene. It is possible to use a mixture of one or more kinds of organic solvents such as the following.

For kneading and dissolving, after adding the primer to the organic solvent,
This can be carried out using a ball mill, a sand mill, a three-roll mill, or the like.

In this case, if a ball mill or sand mill is used, the total solids concentration in the primer solution should be adjusted to about 30% by weight, and if a three-roll mill is used, it should be higher than that in order to improve the kneading effect. preferable. Further, the standard viscosity of the obtained undercoat is preferably 1 to 1000 cp (20°C, total solids concentration 30% by weight).

Next, the primer solution obtained in this manner is applied to at least one surface of the substrate to form a primer layer.

Examples of the base material used here include paper,
In addition to fibrous base materials such as cloth and nonwoven fabrics, smooth films and sheets such as polyethylene, polypropylene, polyester, polyvinyl chloride, cellulose acetate, polycarbonate, cellophane, and polyvinylidene fluoride sheets or films, or composite groups of these Materials can be mentioned.

The undercoat can be applied to the base material using, for example, a gravure coater, a mare bar, a roll coater, an air knife coater, or the like.

The thickness of the undercoat layer in this case is preferably 0.5 microns or more, preferably 1 to 5 microns.

After forming the undercoat layer in this way, 5
Perform drying at ~120°C for 20-300 seconds. Adhesive microparticles are then applied onto this primer layer and allowed to adhere.

Adhesive microparticles can be prepared, for example, from (meth)acrylic esters or (meth)acrylic esters and vinyl monomers containing reactive functional groups, by known suspension polymerization methods, such as those described in U.S. Pat. No. 3,691,140. can be manufactured.

The (meth)acrylic ester preferably has a glass transition temperature of usually 10° C. or lower, preferably 0° C. or lower in order to obtain fine particles that are sticky at room temperature. Such (meth)acrylic esters include (meth)acrylic esters that usually have a linear or branched alkyl group having 2 to 12 carbon atoms, such as butyl (meth)acrylate and isobutyl (meth)acrylate. , sec-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2
- Ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, methyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, etc. These can be used in combination of one or more types. In order to increase the cohesive force of the microparticles, in other words, when using the microparticles as an adhesive, it is necessary to prevent the adhesive from remaining on the adherend by causing a stringing phenomenon when peeled from the adherend. In order to achieve this, vinyl acetate, styrene, acrylonitrile, methacrylonitrile, etc. can be further added in an amount of 50% by weight or less based on the alkyl ester monomer.

The reactive functional group-containing vinyl monomer to be copolymerized with the (meth)acrylic acid ester includes those containing a carboxyl group, hydroxyl group, amino group, glycidyl group, methylol group, formyl group, mercapto group, etc. in the molecule; Examples include acid anhydrides. Examples of such vinyl monomers include (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, N-methylol (meth)acrylamide, and N-butoxymethyl ( Examples include meth)acrylamide, (meth)acrylamide, and maleic anhydride.

Although the shape of the microparticles is not particularly limited, it is preferably spherical because it provides the best removability. In addition, the average particle system is 1 to
The thickness is preferably 150μ, preferably 5 to 100μ.

As a method for applying such adhesive microparticles onto the undercoat layer, the microparticles can be coated with n-hexane, n-heptane, toluene, xylene, ethyl acetate, butyl acetate, 1,1,1-trichloroethane, etc. After dispersion in an organic solvent, a conventional coating method using a knife coater, a reverse roll coater, a gravure coater, a screen printer, or a spraying method can be used.

The amount of coating in this case is calculated on dry weight basis.
The amount is preferably 0.1 to 100 g/m ² , preferably 1 to 30 g/m ² .

After applying and adhering the adhesive microparticles in this manner, the adhesive body of the present invention can be obtained by drying at 60 to 120°C for 30 to 300 seconds.

[Effects of the Invention] As explained above, in the removable adhesive of the present invention, the undercoat layer and the adhesive microparticles formed on the base material are strongly bonded to each other without using a binder. Therefore, it maintains excellent adhesion to the adherend, and at the same time, when pasting and peeling are repeated,
It also has excellent removability, with no adhesive microparticles remaining on the adherend even when rapid peeling is performed.

Therefore, there is no surface staining that occurs when the adherend is a transparent material such as plastic, and there is no so-called "paper stain" that occurs when the adherend is paper such as diazocopy paper. do not have.

Furthermore, since the adhesive body of the present invention does not use a binder, it is possible to shorten manufacturing time and reduce manufacturing costs.

[Examples of the Invention] Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not particularly limited by the Examples. In the examples, "parts" and "%" refer to "parts by weight" and "% by weight," respectively.

Example 1 6 parts of vinyl chloride-vinyl acetate resin (trade name: Denkavinyl #1000GKT, manufactured by Denki Kagaku Kogyo Co., Ltd.) consisting of 91% vinyl chloride, 3% vinyl acetate, and 6% polyvinyl alcohol was dissolved in 70 parts of ethyl acetate. Ta. Next, 24 parts of zinc white was added to this and stirred for 10 minutes in a sand mill. This was applied to one side of a sheet of high-quality paper weighing 70 g/m ² using a gravure coater to a coating thickness of 1 μm. On top of this, sticky microparticles (average particle size) obtained by suspension polymerization
50μ) was coated using a screen printer to give a dry weight of 10g/m ² .

After cutting the obtained adhesive sheet to a width of 25 mm,
Wet diazo copy paper was pressed once with a 5 kg roll, and after 1 hour, it was peeled off at a peeling speed of 180 cm/min.
When the copy paper was peeled off in the horizontal direction, no paper stains or adhesive residue was observed on the copy paper. The peel strength at this time was 250 g/25 mm.

Example 2 9 g of vinyl chloride-vinyl acetate resin (Denka Raku #21 manufactured by Denki Kagaku Kogyo Co., Ltd.) was dissolved in 70 g of a 1:1 mixture of toluene and ethyl acetate. Then,
To this was added 21 g of rutile type titanium white, and the mixture was mixed and ground in a ball mill for 12 hours. This was applied to a 25 μm thick polyester film using a mare bar to give a coating thickness of 1 μm. The same adhesive microparticles as in Example 1 were applied to this using a knife coater to give a dry weight of 8 g/m ² to obtain a sticky body of the present invention.

When an adhesion test similar to that in Example 1 was conducted using this adhesive, there was no paper smudge on the diazo copy paper, and no adhesive remained. At this time, the peel strength is
It was 220g/25mm.

Comparative Example 1 A 10% ethyl acetate solution of vinyl chloride-vinyl acetate resin (Denkaratsuku #1000GKT, manufactured by Denki Kagaku Kogyo Co., Ltd.) was applied to a thickness of 1.5 μm on high-quality paper weighing 70 g/m ² using a mare bar. . The adhesive fine particles used in Example 1 were applied to this using a screen printer to give a dry weight of 10 g/m ² to obtain a sticky body.

When we conducted an adhesion test using this adhesive, we found that
Although there was no paper smudge, sticky microparticles remained on the entire surface of the copy paper that was peeled off.
The peel strength in this case was 150 g/25 mm.

Claims (1)

[Scope of Claims] 1. 35 to 15% by weight of vinyl chloride-vinyl acetate resin and 65 to 85% by weight of an inorganic pigment on at least one side of the base material.
A removable adhesive body characterized in that a plurality of adhesive microparticles are attached via an undercoat layer consisting of % by weight. 2 The adhesive microparticles are a copolymer consisting of 90 to 100% by weight of acrylic acid or methacrylic acid ester and 0 to 10% by weight of a vinyl monomer containing a reactive functional group, and the particle size is in the range of 1 to 150μ. ,
The removable adhesive body according to claim 1, which has a glass transition temperature of -10°C or lower.