JPH0718231A - Heat peelable adhesive tape and peeling method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an adhesive tape that has the same adhesive strength and can be attached like an ordinary adhesive tape, and that can be easily peeled off without leaving any adhesive after cooling to normal temperature when heated. What to do. [Structure] A mixture of non-adhesive resin powder in an adhesive is used as an adhesive layer and is attached to a supporting base material to form an adhesive tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-peelable pressure-sensitive adhesive tape and a peeling method thereof. A heat-peelable adhesive tape is the same as a conventional adhesive tape when it is attached to the surface of another object, but when peeled after being adhered to another object, it can be easily released by heating. It is a thing with.

[0002]

BACKGROUND OF THE INVENTION Adhesive tapes are made by providing an adhesive layer on the surface of a tape-shaped support substrate. In this respect, the heat-peelable adhesive tape is no different from the conventional adhesive tape.

Adhesive tapes and similar adhesive labels (hereinafter collectively referred to as adhesive tapes) have been widely used for product identification, display and fixing of parts to each other. Some of the products and parts to which the adhesive tape is attached can be reused, and it is necessary to remove the adhesive tape once attached for reuse. In such a case, it is desirable that the adhesive tape be easily peeled off. However, even if peeling is easy, it must not be such that it has a low adhesive force and is naturally peeled during use.

Such a heat-peelable pressure-sensitive adhesive tape has been required, for example, when recycling a cartridge used in a printer or the like. That is, after the user has used the adhesive tape to fix the label or parts of the cartridge to each other, when the user wants to use the recovered cartridge again, it is necessary to remove the used adhesive tape. It In order to direct the adhesive tape to such an application, easy peeling was required.

A heat-peelable pressure-sensitive adhesive tape has already been proposed as one that meets such a need. For example, Japanese Patent Publication 5
JP-A 1-24534 proposes that a heat-peelable pressure-sensitive adhesive tape is obtained by incorporating a foaming agent that decomposes with water to generate gas into the pressure-sensitive adhesive layer. However, in this proposal, when peeling, it is necessary to moisten the adhesive tape with water, and therefore the product has to be dried after the peeling, so that there is a drawback that the operation is complicated,
In addition, if the product is not wet enough with water or is not uniform, there is a drawback that it is difficult to perform uniform peeling, and the adhesive tape peels off when the product is used or stored at high temperature and high humidity. There was a drawback that there were things.

Further, JP-A-56-61468, JP-A-60-252681, and JP-A-63-3348.
Japanese Patent Application Laid-Open No. 7-230578 and Japanese Patent Application Laid-Open No. 2-305878 propose that the pressure-sensitive adhesive layer contains a microencapsulated foaming agent to make the pressure-sensitive adhesive tape heat-peelable. According to this proposal, it is explained that when the pressure-sensitive adhesive tape is heated, the encapsulating foaming agent decomposes to generate gas and the pressure-sensitive adhesive tape is easily peeled off. However, if the amount of the encapsulating foaming agent added is small, it is difficult to peel off without leaving any adhesive residue, and if the amount of the encapsulating foaming agent added is so large that no adhesive residue remains, the initial adhesive strength before heating decreases. However, it has a drawback that it cannot be used in applications such as fixing of parts to each other in which force is applied during use.

[0007]

DISCLOSURE OF THE INVENTION The present invention does not reduce the initial adhesive strength before heating or the adhesive strength even under high humidity, and it is not necessary to use water or the like for peeling.
It is an object of the present invention to provide a heat-peelable pressure-sensitive adhesive tape that does not lose its adhesive strength even under high humidity and can be easily peeled off by simply heating.

[0008]

In order to facilitate the peeling of an adhesive tape, the inventor of the present invention has inherently no adhesiveness and is solid at room temperature, but melts when heated to about 100 ° C. An adhesive tape was made by incorporating fine particles of polyethylene into the adhesive layer. It was found that when this pressure-sensitive adhesive tape was heated to about 120 ° C., polyethylene melted to lose the tackiness of the pressure-sensitive adhesive layer, so that the pressure-sensitive adhesive tape was easily peeled off. The present invention has been completed based on such knowledge.

The present invention provides a heat-peelable pressure-sensitive adhesive tape characterized in that a pressure-sensitive adhesive layer containing a non-tacky resin powder is provided on a supporting substrate. This heat-peelable pressure-sensitive adhesive tape has an advantage that it can be easily peeled from an object by heating it after sticking it to the object.

In the present invention, the support base material that has been used for the adhesive tape can be used as it is. More specifically, until now, non-woven fabrics such as cellulose, polyester, rayon, acrylic and nylon, and films such as polyester and polyvinyl chloride have been used, but in the present invention, all such known materials are used. Can be used.

Further, in the present invention, the pressure-sensitive adhesive that has been used in the pressure-sensitive adhesive tape can be used to form the pressure-sensitive adhesive layer. In detail, as the main material, natural rubber,
Rubber-based polymers made of various synthetic rubbers, alkyl acrylates, alkyl methacrylates, and alkyl acrylates, copolymers of vinyl methacrylate and other vinyl-based monomers that can be copolymerized with various additives are added. Can be mentioned. Examples of alkyl acrylate and alkyl methacrylate include n-
Butyl acrylate, n-butyl methacrylate, 2-
Examples include ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isononyl acrylate, and isononyl methacrylate. These alkyl acrylates and alkyl methacrylates may be used alone or in combination of two or more. Examples of the vinyl-based monomer copolymerizable with the alkyl acrylate and alkyl methacrylate in the present invention include acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-substituted acrylamide, hydroxyethyl acrylate, N-vinylpyrrolidone, Maleic acid, itaconic acid, N-methylol acrylamide, hydroxyethyl methacrylate, etc. may be mentioned.

The greatest feature of the present invention is that an adhesive layer is formed by incorporating a non-adhesive resin powder into the above-mentioned adhesive to make an adhesive tape. The non-adhesive resin powder refers to a resin powder that does not essentially adhere to another substance and is solid at room temperature but melts when heated. Usually, as the non-adhesive resin powder, one that is not compatible with the adhesive layer is used. What is incompatible is
Viscoelasticity spectrometer or differential thermal analyzer (DS
The glass transition temperature (Tg) of the adhesive layer to which the non-adhesive resin powder is added, which is measured in C) or the like, is almost the same as the Tg of the adhesive layer to which the powder is not added.

As the non-adhesive resin powder, various powders can be used. For example, powders of polymers or oligomers such as fluororesins such as polyethylene, polypropylene, polyester, polyvinyl chloride and Teflon, perfluoro polymers, polycarbonates, long chain alkyl group-containing polymers and silicone polymers can be used. Here, the long chain alkyl group-containing polymer means polystearyl acrylate, polystearyl acrylamide, polyvinyl stearate, polyvinyl stearyl ether, cellulose tristearate, polyvinyl stearyl carbamate, polystearoyl ethyleneimine, and the like, and the silicone-based polymer. Is a copolymer of phenylmethylsiloxane and dimethylsiloxane, a condensate of methylphenylsiloxane having a 2- (2-hydroxyethylthio) ethyl group and an acrylic polymer having a hydroxyl group, α, ω-dihydroxypolydimethylsiloxane / Triacetoxyvinylsilane / T
It is a condensate of DI and the like, and the perfluoro-based polymer means poly (1,1-dihydroperfluorohexyl methacrylate), poly (N-ethyl, N-perfluorooctanesulfoamidoethyl methacrylate), 11-methylperfluoromethacrylate. It is a methylol compound of fluorooctane sulfoamide diaminotriazine. In particular, non-polar polymers or oligomers such as polyethylene, polypropylene, Teflon, silicone type and perfluoro type are suitable. A solid surface-active agent that is incompatible with the pressure-sensitive adhesive is also preferably used. Such as fatty acids,
Examples include higher alcohols and esters thereof.
Specific examples thereof include polyhydric alcohol esters such as sorbitan monopalmitate, sorbitan monostearate and sorbitan distearate, polyethylene glycol monostearate, polyethylene glycol distearate, propylene glycol monostearate, stearic acid monoglyceride, palmitin. Acid monoglyceride, oleic acid monoglyceride, glycerin fatty acid ester such as stearic acid monodiglyceride or propylene glycol fatty acid ester, mistyryl mystylate, stearyl stearate, fatty acid ester such as distearyl phthalate, stearyl alcohol,
Examples include higher alcohols such as cetyl alcohol, fatty acids such as stearic acid, palmitic acid and myristic acid, alkyl sulfates such as sodium lauryl sulfate, and alkyltrimethylammonium chloride such as stearyltrimethylammonium chloride. The material and particle size of the non-adhesive resin powder are appropriately selected depending on the compatibility with the adhesive layer, the heating temperature for peeling and the heating method. Usually, it is preferable to use a non-adhesive resin powder whose melting point is about 0 to 50 ° C. lower than the surface temperature of the adhesive tape in the heat treatment, but this is also not limited to the above range because it also varies depending on the heating method.

When a particularly suitable non-adhesive resin powder is sought for a commercial product, for example, Flowsen UF manufactured by Sumitomo Seika Co., Ltd.
-80, UF-20, flow beads LE-1080,
CL-2080, HE-5023, waxes such as Viscole 550SP and 660SP manufactured by Sanyo Kasei Co., Ltd., Kao Wax 220 manufactured by Kao Corporation, and fatty acid esters such as Exel T-95.

Generally, the finer the particle size of the non-adhesive resin powder, the faster it can be melted when heated,
Therefore, the heating effect is likely to appear. Moreover, if the particle size is large, the adhesive layer is limited to a thick one. Therefore, it is preferable to use a non-adhesive resin powder having a fine particle size. The smallest particle size obtained at present is about several μm. Therefore, it is usually preferable to use particles having a particle size of 5 to 100 μm. In addition, generally, the smaller the molecular weight of the resin powder, the faster the heating effect is likely to appear. Therefore, the molecular weight of the resin powder is preferably small, and the weight average molecular weight is usually 200 to 1,000,000.
The range from 500 to 500 can be used.
It is preferably about 50,000.

In the present invention, the adhesive layer is composed of 1 to 80% by weight of non-adhesive resin powder and 99 to 20% by weight of adhesive. When the amount of the non-adhesive resin powder is less than this, the effect of addition is not remarkable, and when the amount is too large, the adhesive force of the adhesive layer decreases and the adhesive layer does not function sufficiently. . Among them, non-adhesive resin powder is 5
It is preferable to occupy 50% by weight. The resin powder is preferably dispersed uniformly in the pressure-sensitive adhesive, but for that purpose it is preferable to add a small amount of a thixotropic agent such as Aerosil.

In the present invention, the pressure-sensitive adhesive containing the above-mentioned non-tacky resin powder is provided on the supporting base material to form a pressure-sensitive adhesive tape. In this case, in order to provide the pressure-sensitive adhesive on the supporting substrate, the method which has been used for producing the pressure-sensitive adhesive tape can be used as it is. Further, as disclosed in JP-A-4-142378, a non-adhesive resin powder is added to a photosensitive resin composition that forms an adhesive layer when polymerized,
You may manufacture with the manufacturing method of the same publication. Further, the adhesive tape thus obtained can be adhered onto another object without any change from the conventional adhesive tape. To remove the adhesive tape thus adhered, the adhesive tape is heated. For heating, the adherend may be placed in an oven, irradiated with far infrared rays or infrared rays, or heated air may be blown. The heating temperature is set so that the temperature of the adherend surface to which the adhesive tape is attached becomes 70 to 200 ° C. In particular, when the adherend is a resin product to be reused, the heating temperature is selected within a temperature range in which the resin product is not thermally deformed.

The present invention requires heating the adhesive tape for peeling. However, some articles to which the adhesive tape is attached, such as recycled general-purpose resin molded articles, dislike being heated. In such a case, it is preferable to use a supporting substrate having heat shrinkability as the supporting substrate. As the heat-shrinkable supporting base material,
It is preferable to use a uniaxially or biaxially stretched film such as polyester, polyvinyl chloride or polypropylene, or a woven or non-woven fabric made of stretched fibers of the above resin. The heat shrinkage rate of these films, woven fabrics and non-woven fabrics is determined by the draw ratio during the production of the film or fiber, but is usually about 20 to 80%. The kind and heat shrinkage rate of the resin are appropriately selected and used according to the heating temperature and the heating method for peeling.

If the support base material or the heat-shrinkable support base material is too small in thickness, it does not serve as a support base material. On the contrary, if the support base material or the heat shrinkable support base material is too large, the heat conduction at the time of peeling is delayed, Since the thickness of the tape becomes too thick,
Usually, those having a thickness of 3 to 500 μm are used. Among them,
It is preferably 5 to 60 μm. The supporting base material is preferably subjected to physical treatment such as corona discharge treatment or sputtering treatment or chemical treatment with an undercoating agent (primer) in order to improve the adhesion with the adhesive layer.

As the pressure-sensitive adhesive, those which have been conventionally used as described above can be used. Among them, particularly suitable for the present invention is a copolymer of alkyl acrylate or alkyl methacrylate 50 to 99% by weight and another monomer 50 to 1% by weight copolymerizable therewith, and the weight average molecular weight thereof is 5,000-10,000,
000 is used as the base polymer. To make this polymer, it is usually polymerized in a solvent, but photopolymerization is preferred. Because the polymer polymerized in the solvent is heated by blending non-adhesive resin powder,
This is because it is necessary to dry the solvent, and in that process, problems such as fusion of non-adhesive resin powder particles are likely to occur.
Therefore, in the case where the non-adhesive resin powder has a high melting point or the solvent can be dried at a relatively low temperature, a polymer polymerized in a solvent may be used. On the other hand, the photopolymerizable polymer does not essentially need to be dried by a solvent as disclosed in JP-A-4-142378, so that there is no restriction as described above.

If necessary, the above-mentioned base polymer is added to 100 parts by weight of the base polymer.
You may use what was crosslinked by 0.005-10 weight part of (tri) acrylate type compounds, an isocyanate type compound, an alkyl ether type melamine compound, etc. Further, 1 to 50 parts by weight of a rosin resin, a modified rosin resin, an alicyclic saturated hydrocarbon resin, a terpene resin, a terpene phenol resin, an aromatic modified terpene is added to 100 parts by weight of the base polymer to increase the adhesive strength. Resins, C5 and C9 petroleum resins, coumarone resins and other tackifying resins may be added. In particular, in the case of photopolymerization, a tackifier resin is added in advance to perform polymerization, and therefore an alicyclic saturated hydrocarbon resin, a terpene phenol resin, a coumarone resin and the like, which have less polymerization inhibition, are preferable.

If the adhesive layer containing the non-adhesive resin powder is too thin, it will not function as an adhesive layer, but it is preferable that the tape is not too thick so that the tape does not become too thick and the heating effect appears quickly. Usually, a thickness of 2 to 500 μm is suitable.

The pressure-sensitive adhesive tape according to the present invention includes those in which the pressure-sensitive adhesive layer is provided only on one surface of the supporting base material and those in which the pressure-sensitive adhesive layer is provided on both surfaces of the supporting base material. Adhesive tapes include those having an adhesive layer provided on only one surface of a heat-shrinkable support base material and those having an adhesive layer provided on both surfaces of a heat-shrinkable support base material. In particular, when the pressure-sensitive adhesive layer is provided on both surfaces, the pressure-sensitive adhesive layer of the present invention may be provided on only one surface, and the other surface may be provided with a pressure-sensitive adhesive layer made of a conventional pressure-sensitive adhesive. Such a pressure-sensitive adhesive tape is suitable when a recyclable article and a non-recyclable article are joined by a pressure-sensitive adhesive tape, and the pressure-sensitive adhesive layer of the present invention is attached to the recyclable article side. , Non-recyclable adhesive tape is peeled off.

[0024]

EFFECT OF THE INVENTION Since the adhesive tape according to the present invention contains the non-adhesive resin powder in the adhesive layer provided on the supporting substrate, it can be adhered without lowering the adhesive strength, It can be easily peeled off by heating after adhering. In particular, when a heat-shrinkable base material is used as the supporting base material, the peeling becomes easier.

[0025]

EXAMPLES The present invention will be described below with reference to examples.
In the following, "parts" means "parts by weight".

(Example 1) 87 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 5 parts of acrylic acid, 10 parts of Arakawa Chemical Co. Alcon P-70,
A photopolymerizable composition obtained by adding 0.07 part of hexanediol diacrylate, 10 parts of Sumitomo Seika's Flowsen UF-80, and 2 parts of Ciba-Geigy polymerization initiator Irgacure 651 to a heat shrinkage of 30 μm Of 50 μm on a transparent polyester film (Toyobo Co., Ltd. space clean)
To a thickness of 100 μm, a releasable polyester film was covered thereon, and ultraviolet rays were irradiated to polymerize it to obtain an adhesive tape according to the present invention.

The obtained adhesive tape is 10 cm in length × 2 c
When cut into m-sized pieces and the adhesive strength of this piece to a stainless steel plate was measured, the adhesive strength was 1200 g / 20 m.
It was m. In addition, after attaching this section to a stainless steel plate in an atmosphere of 23 ° C. and 50% RH and leaving it for 30 minutes,
When hot air at 150 ° C. was blown for 30 seconds, peeling occurred at the end of the adhesive tape. After the stainless steel plate was cooled to room temperature, its adhesive strength was measured to be 200 g / 20.
It was mm. After peeling, no adhesive residue was found on the stainless steel plate.

(Example 2) 87 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 5 parts of acrylic acid, 10 parts of Arakawa Chemical Co. Alcon P-70,
A photopolymerizable composition prepared by adding 0.07 part of hexanediol diacrylate, 10 parts of Sumitomo Seika Chemical Co., Ltd. Flowsen UF-80, and 2 parts of Ciba-Geigy polymerization initiator Irgacure 651 to a non-shrinking layer of 30 μm thickness A 50 μm thick coating was applied on a transparent polyester film, and a peelable polyester film was covered thereon and irradiated with ultraviolet rays for polymerization to obtain an adhesive tape according to the present invention.

With respect to the obtained adhesive tape, the adhesive force before and after heating was measured in the same manner as in Example 1. The adhesive force before heating was 1200 g / 20 mm, and after heating it was 4
It was 00 g / 20 mm. After peeling, no adhesive residue was found on the stainless steel plate. In addition, in Example 2, peeling of the end portion as seen in Example 1 was not observed.

(Example 3) 87 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 5 parts of acrylic acid, 10 parts of Arakawa Chemical Co. Alcon P-70,
A photopolymerizable composition obtained by adding 0.07 part of hexanediol diacrylate, 10 parts of Kao Wax 220 manufactured by Kao Corporation, and 2 parts of Irgacure 651, a polymerization initiator manufactured by Ciba-Geigy Co., was used as a non-shrinkable polyester film having a thickness of 30 μm. A pressure-sensitive adhesive tape according to the present invention was obtained by applying a 50 μm-thick coating on top of it, covering it with a peelable polyester film, and irradiating it with ultraviolet rays for polymerization.

With respect to the obtained adhesive tape, the adhesive force before and after heating was measured in the same manner as in Example 1. The adhesive force before heating was 1100 g / 20 mm, and after heating it was 3
It was 00 g / 20 mm. After peeling, no adhesive residue was found on the stainless steel plate. In addition, in Example 3, peeling of the end portion as seen in Example 1 was not observed.

Comparative Example 1 87 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 5 parts of acrylic acid, 10 parts of Arakawa Chemical Co. Alcon P-70,
A photopolymerizable composition prepared by adding 0.07 part of hexanediol diacrylate, 10 parts of Matsumoto Yushi-Seiyaku Co., Ltd. Microsphere F-30, and 2 parts of Ciba-Geigy polymerization initiator Irgacure 651 to a heat of 30 μm A shrinkable polyester film (Space Clean manufactured by Toyobo Co., Ltd.) was applied to a thickness of 50 μm, and a peelable polyester film was covered on the shrinkable polyester film and irradiated with ultraviolet rays to be polymerized to obtain an adhesive tape according to the present invention.

The pressure-sensitive adhesive strength of the obtained pressure-sensitive adhesive tape was measured before and after heating in the same manner as in Example 1. The pressure-sensitive adhesive strength before heating was 1000 g / 20 mm, and after heating 9
It was 00 g / 20 mm. After peeling, an adhesive residue was found on the stainless steel plate. It should be noted that in Comparative Example 1, peeling of the end portion as seen in Example 1 was not observed.

(Comparative Example 2) 87 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 5 parts of acrylic acid, 10 parts of Arakawa Chemical Co. Alcon P-70,
A photopolymerizable composition obtained by adding 0.07 part of hexanediol diacrylate, 30 parts of Matsumoto Yushi-Seiyaku Co., Ltd. Microsphere F-30, and 2 parts of Ciba-Geigy polymerization initiator Irgacure 651 to a heat of 30 μm A shrinkable polyester film (Space Clean manufactured by Toyobo Co., Ltd.) was applied to a thickness of 50 μm, and a peelable polyester film was covered on the shrinkable polyester film and irradiated with ultraviolet rays to be polymerized to obtain an adhesive tape according to the present invention.

With respect to the obtained adhesive tape, the adhesive force before and after heating was measured in the same manner as in Example 1. The adhesive force before heating was 500 g / 20 mm, and after heating, it was 20 g.
It was 0 g / 20 mm. After peeling, an adhesive residue was found on the stainless steel plate. Incidentally, in Comparative Example 2, a slight amount of peeling of the end portion as seen in Example 1 was observed.

Claims (3)

[Claims] 1. A heat-peelable pressure-sensitive adhesive tape, comprising an adhesive layer containing a non-adhesive resin powder provided on at least one surface of a supporting substrate. 2. A heat-peelable pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer according to claim 1 is made of a polymer obtained by photopolymerization. 3. A method for peeling a heat-peelable pressure-sensitive adhesive tape, comprising heating the heat-peelable pressure-sensitive adhesive tape according to claim 1.