JPH02102280A - Microencapsulated self-adhesive - Google Patents

Abstract

PURPOSE:To prepare a self-adhesive not sticking when out of use and exhibiting a mild stickiness when pressed weakly and high stickiness when pressed strongly, by microencapsulating a self-adhesive with a nonsticky shell. CONSTITUTION:A microencapsulated self-adhesive contg. 100 pts.wt. self-adhesive enclosed in 1-30 pts.wt. shell and having a mean particle diameter of 1-300mum is prepared by microencapsulating a monomer for the adhesive with a nonsticky shell followed by the polymerization of the monomer in the microcapsule; dissolving the monomer in another monomer for the shell, emulsifying the resulting solution in water, then polymerizing the monomer for the shell to make microcapsules contg. the monomer for the adhesive, and finally polymerizing the monomer for the adhesive; emulsion-polymerizing the monomer for the adhesive, polymerizing the monomer for the shell in said emulsion to microencapsulated the self-adhesive; or emulsifying both monomers and polymerizing them simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a microencapsulated adhesive and a method for producing the same.

Prior Art and Issues Adhesives are used for a variety of purposes, such as adding initial tackiness to adhesives, Sellotape, bandage plasters, and packing tapes, but no one in which the adhesive component is microencapsulated is known. Not yet.

Therefore, when applying an adhesive to a tape or the like, it is necessary to treat one side of the tape with anti-adhesive treatment with silicone oil, paraffin, etc., or use release paper, etc., to prevent it from sticking when not in use. Furthermore, since they exhibit high tackiness from the beginning, they are inconvenient when it is necessary to position them in advance, and often require adhesives whose initial tackiness can be easily controlled. Furthermore, when it is desired to insert an adhesive into the gap between the surfaces to be adhered, conventional adhesives cannot be used.

In order to solve the above-mentioned problems, the present invention micro-encapsulates the adhesive with a non-adhesive shell forming agent, so that it does not stick when not in use, exhibits gentle adhesion when lightly pressed, and when pressed strongly. The purpose of this invention is to obtain a microencapsulated adhesive that can obtain high adhesiveness by doing so.

SUMMARY OF THE INVENTION The present invention provides a microencapsulated adhesive that encapsulates an adhesive component in a non-adhesive shell.

The adhesive component used in the present invention may be any one conventionally used as an adhesive, such as acrylic adhesive, natural rubber, butyl rubber, styrene butadiene rubber, imprene rubber, rosin, ester gum, polyterpenes, etc. Illustrated. It goes without saying that a combination of typical rubber, butyl rubber, etc. may be used.

The non-adhesive shell of the present invention is an acrylic-based shell made by polymerizing or copolymerizing a component that can microcapsule the adhesive component by polymerization, such as acrylic acid long-chain ester, methacrylic acid long-chain ester, acrylonitrile, vinylidene chloride, etc. Shell-forming components, urethane obtained from polyisocyanate and polyamine, phenol formaldehyde resin obtained from formaldehyde and phenols, melamine formalin resin, guanamine resin, benzoguanamine resin, acetoguanamine resin, Epoquin resin: hisphenol type, phenol novolac type, ortho Cresol novolak type, grindyl ester type; Examples of the resins produced by coacervation include gelatin/gum arabic, gelatin/CMC, etc.

An example of an acrylic yarn pick used for shell formation is
The main ingredients are methyl methacrylate and acrylonitrile,
The copolymerization component is methacrylic acid diacrylic adhesive. Acrylic adhesives, for example, have a main monomer of ester of acrylic acid and a lower or intermediate alcohol, and a relatively less polar monomer such as methacrylate, maleate, acrylonitrile, itaconate, vinyl acetate, or styrene. Examples include those copolymerized with relatively highly polar monomers such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl acrylate, alkylaminoalkyl acrylate, acrylamide, and glycidyl acrylate. The adhesiveness of the adhesive component can be adjusted by appropriately adjusting the type and ratio of its monomers, and by using higher alcohol as the alcohol component that forms the ester of acrylic acid ester, highly polar components are reduced. and the tackiness decreases,
Rather, releasability is developed.

These adhesive components themselves are known and may be appropriately selected from them.

There are two or more types of adhesive components, such as ethyl, n-butyl, isobutyl, n-stearyl, cyclohegycyl, norbornyl, which have a relatively high Tg among acrylic adhesive stells,
Benzyl, 2-hydroxyethyl, 2-hydroxypropyl, glycidyl can be used.

Examples of polyisocyanates include hexamethylene diisocyanate, TDI, MDI, polymethylene polyphenylisocyanate, billet type polyisocyanate, and the like.

Examples of phenols include phenol, catechol, bisphenol A12-chloromethylphenol, and the like.

The non-adhesive shell is used in an amount sufficient to microcapsule the adhesive component, but if it is used too much, the adhesive force will decrease, so it is usually used in an amount of 1 to 30 parts by weight per 100 parts by weight of the adhesive component.
It is preferred to use 3 to 10 parts by weight, especially 3 to 10 parts by weight.

The size of the microencapsulated adhesive is 1 to 300 μm1
Particularly suitable is 5 to 100 μm. If the size of the microcapsule is smaller than 5 μm, it becomes difficult to destroy, and the
If it is larger than μm, it may break during storage or become difficult to coat.

The microencapsulated adhesive of the present invention can be produced by various methods.

One method is to microencapsulate a monomer for the adhesive component in advance with a non-adhesive shell, and then polymerize the monomer inside the microcapsule. This method is particularly useful when, for example, there is a difference between the polymerization conditions for the shell-forming component and the polymerization conditions for the adhesive component. For example, if there are differences in polymerization temperature, solubility, pH catalyst, etc., by setting the conditions, it is possible to polymerize only the shell-forming component in advance, and then polymerize the upper layer for the adhesive component inside the shell. It is.

Specifically, for example, when an acrylic monomer is formed by radical polymerization and a non-adhesive shell is formed from polyisocyanate and polyamine, the former reaction is carried out at the decomposition temperature of the radical initiator, and the latter reaction temperature is set at the polyurethane formation temperature. Since each reaction can be carried out in the same system, there is a method of clocapsulation.

Although this method is the most versatile, the polymerization conditions for the adhesive component and the non-adhesive shell monomer are similar, and it is useful when the first method described cannot be used. Furthermore, since the polymerization is carried out in two stages, no side reactions occur.

Still another method is a method in which shell formation and polymerization of the adhesive component are performed simultaneously. This method is useful when there is a difference in the hydrophilicity of the upper layer for the adhesive component and the hydrophilicity of the monomer for the shell-forming component. For example, as shown in the first method, when polyisocyanate and polyamine are used as shell-forming components, the polyamine is dissolved in water and the polyisocyanate is dissolved in the adhesive monomer. When the conditions are set, the reaction between the polyamine and the polyisocyanate occurs at the interface between the fine particles on the adhesive and water, and the adhesive undergoes a kind of seed polymerization.

The microencapsulated adhesive of the present invention can be obtained as a non-adhesive fine powder or emulsion. Therefore, by dissolving a radical initiator and polyisocyanate in an acrylic monomer, emulsifying this in water in which a polyamine is dissolved, and adjusting the temperature to, for example, around 30°C,
Polyurethane shells of microcapsules are produced by interfacial polymerization of polyisocyanine-1 and polyamines on the surface of the emulsified fine particles, and then the temperature is raised to radically polymerize the acrylic monomers inside the microcapsules.

Such a method can be carried out by employing interfacial polymerization, in-situ polymerization, etc. depending on the type of monomer for the adhesive component and the type and properties of the non-adhesive shell.

If desired, a non-polymerizable adhesive component such as butyl rubber, pine resin, etc. may be dissolved in the monomer for the adhesive component, or other components may be mixed therein.

Another method for obtaining the microencapsulated adhesive of the present invention is to emulsion polymerize the adhesive component monomer in advance, and then polymerize the non-adhesive shell-forming monomer in the emulsion to remove the adhesive. It may be used on a surface, or it may be attached to a label, tape, sheet, etc. Alternatively, it may be used in combination with other binders.

The present invention will be explained below with reference to Examples.

Example 1 1-70 parts of 2-ethylhexyl acrylate, 20 parts of methyl methacrylate, 10 parts of acrylic acid, and 0.5 parts of azobisisobutyronitrile as a radical initiator were uniformly dissolved, and Sumidimar L75 ( 20 parts of Bayer Urethane GmbH: Polyisocyanate) were dissolved. Separately, 50 g of a 10% aqueous solution of PVA was mixed in 500 g of water as an aqueous phase.

Both were mixed and stirred for 1 minute at 5000 rpm using a homogenizer to obtain an O/W emulsion with an average particle size of 5 μm. This emulsion was transferred to a Separable 40 reactor and thoroughly purged with nitrogen. Thereafter, while stirring was continued, 50 g of a 220% aqueous solution of hexamethylene diamide was added dropwise over 30 minutes. (30-40°C). 50°0Xlh after completion of dripping
r ripening to form a polyurea shell. Next, the reaction temperature was raised to 75°C and stirring was continued for 5 hours to carry out radical polymerization of the acrylic monomer. Filter the resulting emulsion.

When dried, a white powder was obtained. This powder did not show any stickiness. When a small amount of powder was crushed with a glass plate, the shell was destroyed and the inclusions came out. After the glass plates were crimped together, a considerable amount of force was required to separate them.

The broken capsules showed strong stickiness.

Example 2 2-ethylhexyl acrylate 1 as adhesive topper
・70 parts, 30 parts of vinyl acetate, and 2 parts of acrylic acid,
Then, 0.5 parts of azobisisovaleronitrile (V-65; manufactured by Wako Tsumugi Co., Ltd.) as a radical initiator and 20 parts of polyisocyanate (Millione-1/MR200) as a shell-forming monomer were dissolved. water 50
5 parts of carboxymethylcellulose was dissolved in 0 parts.

Mix the water phase and oil phase and use a homogenizer for 5000 rpm.
The mixture was stirred at m for 1 minute to obtain an emulsion of d-~511rn. The mixture was stirred for 2 hours while maintaining the pH at 5.0°C to form a shell of melamine-formaldehyde resin. Next, raise the temperature to 80°C to complete curing.
child.

The reaction solution was filtered and the resulting cake was dried. No stickiness was observed in the capsule form. When crushed with a fingertip, the adhesive inside the capsule was released, exhibiting strong stickiness.

Example 4 1.80 parts of 2-ethylhexyl acrylate, 20 parts of vinyl acetate, 2 parts of acrylic acid, and a radical initiator (0.5 part of azohisisovaleronitrile) were uniformly dissolved. 10 parts of hexamethylene diisocyanate was dissolved therein. 500 g of water, 50 g of a 10% PVA aqueous solution, and 5 parts of ethylene glycol were mixed to form an aqueous phase. Mix both and stir with a homogenizer at 5000 rpm for 1 minute to obtain an average of 5
-]0 μm O/W emulsion was obtained. Reaction temperature to 6
The temperature was raised to 5°C and the reaction was carried out for 5 hours. Interfacial polymerization and radical polymerization proceeded at approximately the same rate, and the mixture was transferred to a Rubble 40 flask with an outer shell and thoroughly purged with nitrogen. While stirring, add 50 g of 20% polyethyleneimine aqueous solution to 3
(30-40°C) for 0 minutes to react with polyethyleneimine in the monomer.

After the addition was completed, the mixture was aged at 50°C for 1 hour to form a shell. Next, the reaction temperature was raised to 65°C to polymerize the adhesive particles. The same test as in Example 1 was conducted to confirm the tackiness.

Example 3 90 parts of butyl acrylate, 7 parts of methyl methacrylate, and 3 parts of acrylic acid as adhesive monomers and AIBNo as radical initiator.

1 part was mixed. A monomer phase is mixed with a dispersion of 5 parts of styrene/maleic acid copolymer dissolved in 500 g of water.
The mixture was stirred at 500 Qrpm for 3 minutes to obtain an emulsion with an average particle size of 10 to 20 μm.

The temperature was raised (75° C.) and the mixture was reacted for 2 hours to polymerize the top layer for the adhesive. Cool this solution to room temperature,
Melamine/formalin initial supply 10g (colamine p
6300, Mitsui Toatsu) were mixed. 40 formation and adhesive polymer were produced. The reaction solution was filtered to obtain a cake. Upon drying, a pale and colored powder was obtained. This powder (particle size 10~20 μm) did not show any stickiness. When crushed, adhesive came out from inside, showing strong stickiness.

Examples 5 to 9 Microencapsulated adhesives were obtained using the monomer components shown in Table 1.

The microencapsulated adhesives obtained in Examples 1 to 9 were subjected to a peel test and an adhesive strength test using the methods shown below.

The results are shown in Table-1.

Effects of the Invention When using the microencapsulated adhesive of the present invention by applying it to the release surface of tapes, label posters, etc., a release agent is applied to the surface thereof or a release paper is inserted between them. There's no need. In addition, the adhesive strength can be controlled by the degree of destruction, so when attaching a poster or the like, it is possible to lightly destroy it and temporarily fasten it, and then once the position is precisely aligned, completely destroy it and firmly adhere it. In addition, since it is obtained as a non-adhesive fine powder, it can be inserted into a narrow gap of an object to be adhered to and then pressed to make the object to be adhered adhered.

Patent applicant: Matsumoto Yushi Pharmaceutical Co., Ltd. Agent: 1 person, former patent attorney, Yamaha Haka

Claims (1)

[Claims] 1. A microencapsulated adhesive in which an adhesive component is encapsulated in a non-adhesive shell. 2. The microencapsulated adhesive according to item 1, which has an average particle size of 1 to 300 μm. 3. A method for producing a microencapsulated adhesive, which comprises microencapsulating a monomer for an adhesive component in advance with a non-adhesive shell, and then polymerizing the monomer inside the microcapsule. 4. Dissolve the monomer for the adhesive component in the monomer for the non-adhesive shell, emulsify this in water, polymerize the monomer for the non-adhesive shell to obtain microcapsules encapsulating the monomer for the adhesive component, and then 4. The manufacturing method according to item 3, wherein the adhesive component monomer is polymerized. 5. A method for producing a microencapsulated adhesive, which comprises emulsion polymerizing an adhesive component monomer in advance, and then polymerizing a non-adhesive shell-forming monomer in the emulsion to microcapsule the adhesive. 6. A method for producing a microencapsulated adhesive, which comprises emulsifying an adhesive-forming monomer and a non-adhesive shell-forming monomer and polymerizing them simultaneously.