JP2005220236A - Pressure-sensitive adhesive, microcapsule used for the same and manufacturing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive which, when a tape, film, sheet, sticker, or the like, having adhesion function is stuck on the surface of an adherend substrate, facilitates the positioning in sticking onto a desired sticking portion of the surface of the adherend substrate, enables readjustment or translocation to the desired sticking portion where deemed necessary, and achieves the adhesion function after completion of the positioning, and to provide a microcapsule suitable for the above pressure-sensitive adhesive and a manufacturing method for the microcapsule. <P>SOLUTION: The pressure-sensitive adhesive is formed by dispersing the microcapsule, which occludes a water-based adhesive and can release the inclusion by being destroyed or crushed by application of an external force, into a removable adhesive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure-sensitive adhesive used for tapes, films, sheets, stickers and the like, and relates to a pressure-sensitive adhesive that changes from a temporarily fixed state to a permanently bonded state. The present invention also relates to a microcapsule suitable for the pressure-sensitive adhesive and a method for producing the same.

  Conventionally, when adhering to the surface of the substrate to be adhered in a tape, film, sheet, sticker or the like having an adhesive function, it is easy to align the surface of the substrate to be adhered to a desired adhesion site, and Moreover, the proposal which enables the correction movement to the said desired sticking site | part as needed was made | formed. Adhesives used for these tapes, films, sheets, stickers, etc. are difficult to stick to the desired part of the surface of the substrate to be adhered, and the initial adhesive strength is large. Therefore, the above proposal has been made to solve these problems.

  For example, Patent Document 1 proposes to microencapsulate an adhesive component in a non-adhesive shell. However, in this proposal, since the shell is not sticky, there is a problem that it is difficult to fix the shell to a desired sticking site and destroy the microcapsule.

  Patent Document 2 proposes a pressure-sensitive adhesive layer characterized in that the adhesive layer has small, fragile or collapsible non-adhesive protrusions that are uniformly distributed on at least one surface thereof. This proposal proposes that a friable or collapsible non-adhesive hollow microballoon, such as a hollow microballoon of a resin such as urea-formaldehyde resin, or a hollow glass microballoon, on at least one surface of the adhesive layer. It is distributed evenly to reduce the initial adhesive force, and when the pressure is applied to the adherend substrate, the hollow microballoons are ruptured or crushed to develop the adhesive force of the adhesive layer. However, in this proposal, the change in the adhesive force before and after the bonding is caused by the adhesive force of the same adhesive, so that the change before and after the bonding becomes unclear. .

Japanese Patent Laid-Open No. 2-102280 Japanese Patent Publication No.44-3120

  Therefore, when the present invention is bonded to the surface of the substrate to be bonded in a tape, film, sheet, sticker or the like having an adhesive function, the bonding position alignment to a desired bonding site on the surface of the substrate to be bonded is performed. It is another object of the present invention to provide a pressure-sensitive adhesive that facilitates the correction and enables correction movement to a desired sticking site as required, and that performs an adhesive function after completion of alignment. It is another object of the present invention to provide a microcapsule suitable for the pressure-sensitive adhesive and a method for producing the same.

  As a result of intensive research to solve the above problems, water-based adhesives are encapsulated in microcapsules, and these adhesive-encapsulated microcapsules are dispersed in a releasable adhesive with low initial adhesiveness, thereby preventing pressure bonding. In the state, since only the releasable adhesive works, it is possible to correct and move it to the desired application site on the surface of the substrate to be bonded. It has been found that when it is crushed and the water-based adhesive is released, it can be a pressure-sensitive adhesive that performs an adhesive function, and the present invention has been completed.

  That is, the present invention provides a microcapsule comprising an aqueous adhesive. The aqueous adhesive is preferably at least one emulsion adhesive selected from the group consisting of vinyl acetate emulsion, vinyl acetate / acrylic emulsion, and acrylic emulsion. The microcapsules are emulsified by dispersing an aqueous phase containing an aqueous adhesive in an oil phase containing a microcapsule wall-forming substance, and dispersing this in an aqueous phase to obtain a W / O / W type emulsion. It can be produced by adding a curing agent to the emulsion and curing.

  The pressure-sensitive adhesive of the present invention is characterized by containing microcapsules encapsulating the aqueous adhesive as an essential component. The microcapsules are preferably those that can be broken or crushed by applying an external force to release the inclusions. When the pressure sensitive adhesive of the present invention disperses a microcapsule containing a water-based adhesive having a high initial adhesive force in a releasable adhesive and temporarily fixes it to a desired application site, and correction movement is required Makes it possible to correct the movement of the attachment site, and also allows permanent adhesion by the action of breaking or crushing the microcapsules.

  As described above, the pressure-sensitive adhesive of the present invention can be corrected and moved to a desired bonding site on the surface of the substrate to be bonded because only the detachable pressure-sensitive adhesive works in a state where it is not pressure-bonded. Then, an external force such as a shearing force is applied and pressure-bonded, and the microcapsule is broken or crushed to release the water-based adhesive, thereby performing an adhesive function.

  Further, according to the production method of the present invention, when used for a transfer tape or the like, it sticks without being broken by the transfer pressure, and is not broken even when the movement is corrected, but it is broken at the time of crimping, and at the time of production. Therefore, it is possible to provide a stable microcapsule in which the inclusion water is less leaked and the inclusion water does not volatilize over time.

  The present invention will be described in detail below. The pressure-sensitive adhesive of the present invention contains a microcapsule containing an aqueous adhesive as an essential component. The pressure-sensitive adhesive of the present invention can be corrected and moved at the application site. When an external force is applied and pressure-bonded, the microcapsule is broken or crushed, and the water-based adhesive is released to perform an adhesive function.

  In order to obtain the pressure-sensitive adhesive of the present invention, it is preferable to disperse microcapsules containing an aqueous adhesive in a re-peelable pressure-sensitive adhesive. For dispersion, a dispersant or the like may be appropriately used. The compounding amount of the microcapsules in the pressure-sensitive adhesive is preferably 30 to 150 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive. If it is less than 30 parts by weight, the adhesiveness is insufficient, and if it exceeds 150 parts by weight, it becomes difficult to disperse the microcapsules in the pressure-sensitive adhesive. From the viewpoint of sufficient adhesion, 40 to 90 parts by weight is more preferable.

  When the adhesive strength of the pressure-sensitive adhesive is high, correction movement to a desired sticking site cannot be performed when sticking to the surface of the sticking substrate. Accordingly, the adhesive strength of the adhesive is suitably in the range of 10 to 1000 g / 25 mm (SUS), more preferably 10 to 500 g / 25 mm (SUS), according to the test method of JIS Z 0237.

  The re-peelable pressure-sensitive adhesive may be a water-based pressure-sensitive adhesive or a non-water-based pressure-sensitive adhesive as long as it can be re-peeled. As the water-based pressure-sensitive adhesive, emulsion-type pressure-sensitive adhesives such as vinyl acetate, vinyl acetate / acrylic, and acrylic can be used. Non-aqueous adhesives include rubber adhesives such as natural rubber and synthetic rubber, acrylic adhesives such as acrylic ester copolymers and vinyl acetate / acrylic ester copolymers, urethane adhesives, and silicone adhesives. An agent or the like can be used. Among these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used regardless of whether they are water-based or non-water-based removable pressure-sensitive adhesives.

  As long as the water-based adhesive included in the microcapsule has a sufficient adhesive force, the form and type thereof can be used without limitation. For example, an aqueous solution of an adhesive water-soluble polymer or an aqueous emulsion adhesive may be used. The microcapsules may contain additives such as surfactants and viscosity modifiers used during production. Here, examples of the water-soluble polymer include polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). Examples of the water-based emulsion adhesive include vinyl acetate emulsion, vinyl acetate / acrylic emulsion, and acrylic emulsion. Among water-based adhesives, water-based emulsion type adhesives are preferably used because of their good adhesion.

  The above water-based emulsion type adhesive may be used in combination with two types of emulsions in order to adjust the adhesive strength. For example, the initial adhesive force can be increased by using an acrylic emulsion having a low Tg and a vinyl acetate emulsion having a strong adhesive force. Similarly, an adhesive water-soluble polymer such as polyvinyl pyrrolidone or polyvinyl alcohol can also be used as an adhesion aid. As the main agent, Aika Aibon series (Aika Industry Co., Ltd.), Nicazole series (Nippon Carbide Industry Co., Ltd.), Movinyl series (Clariant Polymer Co., Ltd.), etc. One type can be used.

  The adhesive strength of the water-based adhesive varies depending on the type of the substrate to be adhered, but the adhesive strength value according to the test method of JIS Z 0237 is preferably 1000 g / 25 mm (SUS) or more, more preferably 1500 to 2500 g / The range is 25 mm (SUS).

  The material of the wall material of the microcapsule is not compatible with the pressure-sensitive adhesive because the object of the present invention cannot be achieved if the microcapsule dissolves when dispersed in the removable adhesive (non-aqueous pressure-sensitive adhesive). A material that does not melt and that has little influence on the adhesive force even after the microcapsules are broken or crushed is desirable. Examples of the wall material include urethane resin, phenol formaldehyde resin, styrene resin, acrylic resin, vinyl acetate resin, epoxy resin, gelatin, and the like, and a crosslinking agent may be appropriately added.

  The size of the microcapsules is preferably 1 to 300 μm, particularly 5 to 100 μm. If the size of the microcapsule is less than 1 μm, it is difficult to break or crush, and if it exceeds 300 μm, it is difficult to disperse in the adhesive.

  A microcapsule containing an aqueous adhesive can be obtained by using a microcapsule preparation method such as an in-situ polymerization method, an interfacial polymerization method, a submerged curing method, a coacervation method, or a submerged drying method. . Among these preparation methods, the interfacial polymerization method and the submerged curing method are preferable in terms of the state and strength of the resulting microcapsule wall. In other words, there is little leakage of inclusions at the time of manufacture, the inclusion water does not volatilize over time, it is stable, it is stuck without being destroyed by transfer pressure, and it is not destroyed even when moving, but it is destroyed when crimping It is excellent in that it can maintain the strength.

  Here, interfacial polymerization is a method in which a substance to be encapsulated in microcapsules is dissolved or dispersed in a dispersed phase, and two or more kinds of microcapsule wall forming substances are supplied from the continuous phase side and the other from the dispersed phase side. In this method, a microcapsule wall is formed by reacting at the interface between both phases. In the liquid curing method, a polymer solution containing what is to be encapsulated in a microcapsule is dispersed in a continuous phase that is incompatible with this to form droplets, and the polymer is insolubilized with a curing agent or a crosslinking agent. A capsule wall.

  When the microcapsules of the present invention are produced by the interfacial polymerization method, first, an aqueous adhesive is dissolved or dispersed in an aqueous phase, and this is dispersed in an oil phase containing a microcapsule wall-forming substance to form a W / O type emulsion. After being obtained, this emulsion is dispersed in an aqueous phase of 1.5 to 20 times by weight (preferably 2.5 to 10 times by weight) to obtain a W / O / W type emulsion. It is preferable to add a curing agent that reacts with the substance to form a capsule wall and cures by reaction. The ratio of the water phase to the oil phase in the W / O emulsion is preferably water phase / oil phase = 10/90 to 70/30 (weight ratio), and 15/85 to 65/35 (weight ratio). More preferably. The reaction temperature is preferably from 0 ° C to 60 ° C. When the reaction temperature is less than 0 ° C, the reaction rate is slow, and when it exceeds 60 ° C, a dense capsule wall is hardly formed.

  Examples of the microcapsule wall-forming substance contained in the oil phase include isocyanates, such as hexamethylene diisocyanate, metaphenylene diisocyanate, toluylene isocyanate, 2,4-tolylene diisocyanate, toluylene isocyanate and trimethylolpropane. Reaction products, isocyanate monomers such as 3,3-dimethyldiphenyl-4,4-diisocyanate, diphenylmethane-4,4-diisocyanate, triphenylmethane triisocyanate, naphthalene-1,5-diisocyanate, modified or derivatives of isocyanate, etc. What forms a polyurethane wall can be used. As the interfacial polymerization method, a polyamide capsule wall can be formed by using acid chloride, sebacoyl chloride, or terephthalic acid chloride, but polyurethane is more preferable in terms of capsule strength and hardness.

  The solvent used for the oil phase is preferably a non-aqueous solvent that is incompatible with water. If the reaction solvent remains in the capsule, the adhesive force after the capsule breakage does not appear, so the solvent is volatilized and collected after the capsule wall is formed. Therefore, it is preferable that the solvent has a low boiling point, and those having a boiling point of 35 ° C. to 90 ° C. are suitably used. Examples of such a solvent include hexane, isohexane, 3-methylpentane, neohexane, 2,3-dimethylbutane, cyclopentane, cyclohexane, chloroform, diethyl ether, ethyl acetate, and methyl ethyl ketone. These solvents may be used alone, or two or more kinds may be mixed and used in an arbitrary ratio.

  A surfactant and a viscosity modifier may be added when forming the W / O emulsion and / or the W / O / W emulsion. The addition amount of the surfactant is 1 to 50% by weight, preferably 5 to 30% by weight, based on the whole emulsion. The surfactant is preferably HLB 7 or less, more preferably HLB 4 or less. Examples of the surfactant include propylene glycol stearate such as propylene glycol monostearate, glyceryl fatty acid ester such as glyceryl monomyristate, glyceryl monostearate, glyceryl monooleate, and glyceryl monoisostearate, and tristearic acid. Examples include sorbitan fatty acid esters such as sorbitan, sorbitan sesquioleate and sorbitan trioleate, and polyoxyethylene sorbite fatty acid esters such as hexastearic acid POE (6) sorbit. These surfactants may be used alone or in combination of two or more at any ratio.

  Although the hardening | curing agent used for polyurethane wall formation is not specifically limited, Amin is mentioned as a representative example. The amine may be used in a ratio of amine group to NCO group of isocyanate in the range of 1: 1 to 1: 7, preferably 1: 2 to 1: 7. Examples of amines include stearylamine, oleylamine, dodecylamine, ethylenediamine, 1,3-propylenediamine, diethylenetriamine, triethylenetetramine, 1,6-hexamethylenediamine, and other aliphatic amines, xylenediamine, and N-aminopropylpimine. Examples thereof include amines having a cyclic structure such as verazine. Of these amines, aliphatic diamines are preferred.

  After completion of the curing reaction, the solvent in the microcapsules is volatilized by heating at a temperature of 80 ° C. or lower, or by heating at a lower temperature under reduced pressure. After the solvent is volatilized, the microcapsule is separated from the solution and dried to obtain a microcapsule containing an aqueous adhesive.

  The pressure-sensitive adhesive of the present invention can be used for applications in which a pressure-sensitive adhesive is used, such as a tape, a film, a sheet, and a sticker.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only the following Examples. In each example, parts and percentages are by weight unless otherwise specified.

(Preparation of microcapsules)
In 30.0 parts of a mixed solvent of ethyl acetate and cyclopentane, 7.0 parts of a reaction product of 75 parts of toluylene isocyanate and trimethylolpropane dispersed in 100 parts of ethyl acetate was dissolved, and Span 80 was added to 3.0 parts. The part was melted. A solution obtained by adding 3.0 parts of a 5% aqueous solution of polyvinyl alcohol to 9.0 parts of an aqueous emulsion pressure-sensitive adhesive Nicazole TS2002 (manufactured by Nippon Carbide Industries Co., Ltd., acrylic resin emulsion; solid content 60%) at 3000 rpm, 5 Dispersion was carried out using a minute disper to prepare dispersion A (W / O type). Separately, an aqueous solution B was prepared by adding 150 parts of water to 150 parts of a 5% aqueous solution of polyvinyl alcohol. Dispersion A was added to this aqueous solution B and dispersed at 3000 rpm for 5 minutes to obtain dispersion C (W / O / W type). A solution obtained by dissolving 4.97 g of 1,6-hexanediamine in 10 g of water was added to Dispersion C, and the mixture was heated at 55 ° C. for 2 hr with gentle stirring, and further heated at 80 ° C. for 1 hr. The product was filtered, and water-based adhesive-encapsulated microcapsules (average particle size 25 μm) were taken out.

(Preparation of microcapsules)
A solution obtained by dispersing 6.0 parts of PVP 20% aqueous solution, aqueous adhesive Nicazole TS1537 (manufactured by Nippon Carbide Industries Co., Ltd., acrylic resin emulsion; solid content 55%), 0.02 parts of Tween 20 with chloroform Disperse in 30.0 parts of a mixed solvent of isohexane, 3.0 parts of dimethicone copolyol and 6.5 parts of a two-component polyisocyanate resin (Takenate D-103H) to obtain dispersion D (W / O type) ). Dispersion D was dispersed in 300.0 g of water in which 2.0 parts of a viscosity modifier was dissolved to prepare a dispersion (W / O / W type). To the dispersion, 2.49 parts of 1,6-hexanediamine was added, and the dispersion was heated to 65 ° C. and stirred for 3 hours, followed by filtration, and the resulting microcapsules (average particle size 50 μm) were taken out.

(Preparation of pressure-sensitive adhesive)
Two parts of the crosslinking agent CK-101 are added to 200 parts of the non-aqueous acrylic pressure-sensitive adhesive Nisset KP-1410 (manufactured by Nippon Carbide Industries Co., Ltd.), and 80 parts of the aqueous adhesive-encapsulating capsule obtained in Example 1 is added and stirred. And dispersed into a pressure sensitive adhesive.

  The pressure-sensitive adhesive was coated on release paper so that the thickness after drying was 50 μm, and processed into a tape shape. This pressure-sensitive adhesive tape was transferred to a high quality paper, and the high quality paper was attached to confirm the effect. As a result, as shown in Table 1 below, the initial adhesive force was sufficiently small and the movement on the adherend was sufficiently possible. It became impossible to correct, and when trying to move it forcibly, the quality paper was destroyed.

(Preparation of pressure-sensitive adhesive)
To 200 parts of non-aqueous acrylic pressure-sensitive adhesive Nissetsu KP-1420 (manufactured by Nippon Carbide Industries Co., Ltd.), 1.5 parts of the crosslinking agent CK-101 was added, and 100 parts of the aqueous adhesive-encapsulated microcapsules obtained in Example 2 were added. The mixture was stirred and dispersed to obtain a pressure sensitive adhesive.

  The effect of the pressure-sensitive adhesive was confirmed in the same manner as in Example 3. As a result, as shown in Table 1 below, the initial adhesive force was sufficiently small and the movement on the adherend was sufficiently possible. It became impossible to correct, and when trying to move it forcibly, the quality paper was destroyed.

(Preparation of pressure-sensitive adhesive)
100 parts of the water-based adhesive-encapsulated microcapsules obtained in Example 1 were added to 200 parts of the water-based acrylic pressure-sensitive adhesive Nicazole TS1449 (manufactured by Nippon Carbide Industries Co., Ltd.), and dispersed to obtain a pressure-sensitive adhesive.

  The effect of the pressure-sensitive adhesive was confirmed in the same manner as in Example 3. As a result, as shown in Table 1 below, the initial adhesive force was sufficiently small and the movement on the adherend was sufficiently possible. It became impossible to correct, and when trying to move it forcibly, the quality paper was destroyed.

(Comparative Example 1)
200 parts of non-aqueous acrylic adhesive NISSETSU PE-115E (manufactured by Nippon Carbide Industries Co., Ltd.), 2 parts of cross-linking agent CK-101 added and stirred, coated on release paper so that the thickness after drying is 50 μm And processed into a tape shape. The pressure-sensitive adhesive tape was transferred to a high quality paper, the high quality paper was bonded, and the effect was tested. As a result, as shown in Table 1 below, the initial adhesive force was large, the movement on the adherend was not possible at all, and the correction movement of the sticking site was impossible.

(Comparative Example 2)
Add 200 parts of the cross-linking agent CK-103 to 200 parts of the non-aqueous acrylic adhesive Nisset KP-1410 (manufactured by Nippon Carbide Industries Co., Ltd.) and stir it on the release paper so that the thickness after drying becomes 100 μm. Coated and processed into a tape. About this pressure-sensitive adhesive tape, the tape was transferred to a high-quality paper, and the high-quality paper was bonded together to test its effect. As a result, as shown in Table 1 below, the initial adhesive force is small, and movement on the adherend is possible, but it is still possible to be peeled after pressure bonding, and the high-quality paper is completely adhered. Was impossible.

The evaluation criteria for the pressure sensitive adhesive shown in Table 1 were as follows. In addition, the value of the adhesive force in a table | surface is the value (unit: g / 25mm (SUS)) of the adhesive force by the test method of JISZ0237.
(1) Adhesive state before crimping ○: Removable and can move without leaving glue on the paper surface ×: Initial adhesive force is large and cannot be removed again (2) Adhesive state after crimping ○: Unreleasable, unreasonably Strong adhesion that destroys the paper when attempting to move ×: state that peels off without adhesion

Claims (5)

A microcapsule comprising an aqueous adhesive. The microcapsule according to claim 1, wherein the aqueous adhesive is at least one emulsion adhesive selected from the group consisting of a vinyl acetate emulsion, a vinyl acetate / acrylic emulsion, and an acrylic emulsion. A pressure-sensitive adhesive comprising the microcapsule according to claim 1 or 2 as an essential component. The pressure-sensitive adhesive according to claim 3, wherein the microcapsules can be broken or crushed by applying an external force to release inclusions. An aqueous phase containing an aqueous adhesive is dispersed in an oil phase containing a microcapsule wall-forming substance and emulsified, and this is dispersed in an aqueous phase to obtain a W / O / W type emulsion. The method for producing microcapsules according to claim 1, comprising adding and curing.