JPH0762304A - Production of pressure-sensitive adhesive tape - Google Patents

Abstract

PURPOSE:To produce a pressure-sensitive adhesive tape having sufficiently high initial tack to an adherend and peelable through heat treatment, by applying a photopolymerizable composition consisting of an acrylate monomer, a tackifier resin, etc., to one side of a specified synthetic resin film or sheet and irradiating it with light. CONSTITUTION:An uncured or semicured photopolymerizable composition consisting of an acrylate monomer, a vinyl monomer copolymerizable therewith, a tackifier resin, a cross-linking agent and a photopolymerization initiator is applied to at least one side of a synthetic resin film or fibrous sheet having a heat shrinkage of 5-80% and then is polymerized by irradiation with light. As the resin film, a uniaxially or biaxially oriented film of, e.g. a polyester, polystyrene, polyvinyl chloride, polypropylene or polyethylene is used. Examples of the tackifier resin include a rosin resin, a terpene resin and a chroman indene resin. It is desirable that the amount of the tackifier resin to be incorporated is 10-70 pts.wt. based on 100 pts.wt. of the monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an adhesive tape which can be re-peeled by heating.

[0002]

2. Description of the Related Art Conventionally, there is a demand for an adhesive tape which can be used as a masking tape when coating automobiles and can be easily removed by heating after coating and which can be peeled off by heating for the purpose of simplifying the work. ing.

As the adhesive tape for the above purpose, an adhesive tape having a base sheet provided with an adhesive layer containing a heat-expandable resin (JP-A-60-252681), a heat-shrinkable substrate with a foaming agent It has been reported that an adhesive layer containing it is provided (JP-A-4-88075).

[0004]

However, the above-mentioned pressure-sensitive adhesive tape has a low adhesive strength at room temperature and cannot be used for fixing purposes under load, and is limited to masking and labels.

Further, in the case of producing such an adhesive tape, a direct application method in which an adhesive solution is directly applied to a base material, and a transfer in which an adhesive layer is once formed on a release sheet and then bonded to the base material Although there is a method, in the case of the direct application method, after applying the pressure-sensitive adhesive solution, it is necessary to heat to dry the solvent, but it is usually used for drying the pressure-sensitive adhesive.
When a temperature of about 00 ° C. is applied, the base material shrinks, which causes a problem that the function as a product cannot be obtained.
On the other hand, in the case of the transfer method, since the pressure-sensitive adhesive layer formed separately is attached to the base material, heat is not applied, but the number of steps is increased as compared with the direct application method, the productivity is poor, and the synthetic resin film or There is a problem that a sufficient adhesive force (anchor property) of the pressure-sensitive adhesive layer cannot be expressed with respect to the fiber sheet. Further, there is a problem that the solvent-type pressure-sensitive adhesive is not suitable in terms of removability since it has a high adhesion promotion after being adhered to an adherend.

The present invention has been made in view of the above problems, and an object of the present invention is to have a sufficient adhesive force at room temperature and to easily re-heat it by performing a relatively low temperature heat treatment at about 100 ° C. It is intended to provide a method for producing a peelable adhesive tape by a direct coating method.

[0007]

In the present invention, the heat shrinkage ratio is 5
A synthetic resin film or fibrous sheet with ˜80% is used. Here, the heat shrinkage rate is the shrinkage rate of the film area defined by the following equation when left at 100 ° C. for 10 minutes. Shrinkage (%) = [(length before heating x width)-(length after heating x width)] x 100 / (length before heating x width)

When the heat shrinkage rate of the synthetic resin film or the fibrous sheet is less than 5%, the removability is lost, and when the shrinkage rate exceeds 80%, it is substantially melted by heat and used as a substrate. No, it is preferably 30 to 80%. Examples of such synthetic resin film include uniaxially or biaxially stretched films of polyester, polystyrene, polyvinyl chloride, polypropylene, polyethylene and the like. Examples of the fibrous sheet include woven or non-woven fabric made of the same synthetic resin as described above.

The thickness of the synthetic resin film or the fibrous sheet may be appropriately selected depending on the application, but is usually preferably 10 to 200 μm from the viewpoint of ease of use. The photopolymerizable composition used in the present invention comprises an acrylate monomer, a vinyl-based monomer copolymerizable with the acrylate monomer, a tackifying resin, a crosslinking agent and a photoinitiator.

Examples of the acrylate monomer include n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate and isononyl (meth) acrylate.

As the vinyl-based monomer copolymerizable with the acrylate monomer, (meth) acrylic acid, (meth) acrylamide, (meth) acrylonitrile, N--
Substituted acrylamide, 2-hydroxyethyl (meth) acrylate, N-vinylpyrrolidone, maleic acid, itaconic acid, N-methylolacrylamide and the like can be mentioned. It is preferable that 50 to 99% by weight of the acrylate monomer and 50 to 1% by weight of the vinyl monomer are copolymerized.

The tackifying resin is a rosin resin,
Alicyclic saturated hydrocarbon resin, terpene resin, terpene phenol resin, aromatic modified terpene resin, carbon number 5 or 9
Examples thereof include petroleum-based petroleum resins and coumarone-indene resins, and aliphatic saturated hydrocarbon resins, terpene resins, terpene-phenol resins or coumarone-indene resins are particularly preferable in terms of increasing the initial adhesive strength. The addition amount of the tackifying resin is the total amount of the acrylate monomer and the vinyl monomer 1
10 to 70 parts by weight is preferable with respect to 00 parts by weight.

The cross-linking agent is an acrylate monomer,
It is for cross-linking an acrylate monomer and a vinyl-based copolymerizable monomer to impart cohesive force. For example, di (tri) acrylate can be mentioned, and specifically, hexanediol di (meth) acrylate, ( Poly) ethylene glycol di (meth) acrylate, (poly) propylene di (meth) acrylate, neopentyl glycol (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate And polyfunctional monomers such as urethane acrylate.

The amount of the crosslinking agent added is preferably 0.001 to 10 parts by weight based on 100 parts by weight of the acrylate monomer and 100 parts by weight of the vinyl monomer copolymerizable with the acrylate monomer.

Examples of the photopolymerization initiator which can be used in the present invention include acetophenone type, benzoin ether type, ketal type, halogenated ketone type and acylphosphinoxide type. 4 as an example of acetophenone
-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α '
-Dimethyl-acetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone and the like, examples of the benzoin ether type include benzoin ethyl ether and benzoin isopropyl ether, and examples of the ketal type include benzyl dimethyl ether. An example is ketal.

From the viewpoint of the polymerization reaction rate, the amount of the photopolymerization initiator added is preferably 0.001 to 10 parts by weight based on 100 parts by weight of the acrylate monomer and a vinyl-based monomer copolymerizable with the acrylate monomer.

Further, by adding a heat-expandable resin, a foaming agent or the like to the above photopolymerizable composition, a further re-peeling effect can be obtained. Examples of the heat-expandable resin include Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.), Expancel (trade name, manufactured by Expancel Co., Ltd.), Sun Microsphere (trade name, manufactured by Dow Chemical Co., Ltd.), and the like. To be

The amount of the heat-expandable resin added is preferably 3 to 40 parts by weight with respect to 100 parts by weight of the photopolymerizable composition. This is because if it is less than 3 parts by weight, it is difficult to improve the re-peeling effect, and if it exceeds 40 parts by weight, the initial adhesive strength is lowered.

Examples of the foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate,
Inorganic compounds represented by ammonium nitrite, sodium borohydride, azides, etc., azo compounds such as azobisbutyronitrile, azodicarbonamide, barium azodicarboxylate, toluenesulfonylhydrazide, diphenylsulfone-3, Hydrazine compounds such as 3'-disulfohydrazine, 4,4'-oxybis (benzenesulfohydrazide), allylbis (sulfohydrazide), ρ-toluylenesulfonyl semicarbazide,
Semicarbazide compounds such as 4,4′-oxybis (benzenesulfonyl semicarbazide), 5-morpholyl-
Triazole compounds such as 1,2,3,4-thiatriazole and N- such as N, N'-dinitrosoterephthalamide
Examples thereof include organic compounds represented by nitroso compounds.

Further, if necessary, a viscosity modifier may be added. The viscosity of the photopolymerizable composition can be increased by adding the viscosity modifier to the above acrylate monomer and 0.1 to 30% by weight relative to the total amount of the vinyl monomer copolymerizable with the acrylate monomer. The thickness formed during application can be maintained. as a result,
It becomes easy to adjust the thickness of the pressure-sensitive adhesive layer formed after light irradiation. As such, in organic type acrylic rubber,
In the case of inorganic type, preferred is Aerosil.

Examples of the light used in the present invention include visible light, ultraviolet rays, and electromagnetic waves such as electron beams. Usually, ultraviolet rays are preferably used in terms of reactivity and handleability. Furthermore, the wavelength is 300 to 400 in the ultraviolet region.
Those around nm are most preferable. The light intensity and the irradiation amount may be appropriately selected depending on the type and thickness of the photopolymerizable composition and other conditions.

The thickness of the pressure-sensitive adhesive layer formed by irradiating with light is not particularly limited, but is usually preferably 10 to 100 μm from the viewpoint of ease of use as a pressure-sensitive adhesive tape.

As a method of applying the above-mentioned photopolymerizable composition to a heat-shrinkable synthetic resin film or fibrous sheet,
A method of direct coating, or once, after coating on a release sheet, a method of transferring to the film or fibrous sheet may be mentioned, but in the present invention where heat is not applied, direct coating is more productive, Further advantages can be utilized.

Further, also in the coating method by transfer, after the photopolymerizable composition is coated on a transparent release sheet, it is once irradiated with light to be polymerized to a certain extent to obtain a semi-cured photopolymerizable composition. If necessary, a method of forming a pressure-sensitive adhesive layer by laminating the photopolymerizable composition surface to the film or fibrous sheet, and further irradiating light from the back side of the release sheet to completely complete the polymerization is also possible. It is possible.

As the conditions for advancing the photopolymerization reaction, oxygen in the atmosphere usually inhibits the polymerization, so that a peelable film that transmits light or an inert gas atmosphere is attached to the coated surface of the photopolymerizable composition. It is preferable to carry out in a combined state.

[0026]

The base material of the pressure-sensitive adhesive tape obtained in the present invention is a synthetic resin film or a fibrous sheet having a heat shrinkage ratio of 5 to 80%, so that the base material layer can be shrunk by heating. Further, a pressure-sensitive adhesive layer is formed by simultaneously irradiating with light a photopolymerizable composition consisting of an acrylate monomer, a vinyl-based monomer copolymerizable with the acrylate monomer, a tackifying resin, a cross-linking agent and a photopolymerization initiator in the simultaneous presence. Therefore, as compared with the solvent-based pressure-sensitive adhesive, the tackifying resin is uniformly dispersed in the pressure-sensitive adhesive layer, has a high initial adhesive strength even at room temperature, and does not promote adhesion. As a result, the base material layer shrinks when heated, and the adhesive tape can be peeled off from the adherend.

[0027]

EXAMPLES Examples of the present invention will be described below. (Examples 1 to 3) 2-ethylhexyl acrylate 82
Parts (parts by weight, the same applies hereinafter), 8 parts of N-vinylpyrrolidone,
Carboxyethyl acrylate 10 parts, coumarone indene resin (Nippon Steel Chemical Co., Ltd., S-crystal A-120
S) 15 parts, hexanediol diacrylate 0.06
Part, 2.5 parts of acrylic rubber and 1.3 parts of 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (Dalocure 2959, manufactured by Merck & Co., Inc.) were used for releasability. And was coated on one side of a transparent polyester film with a thickness of 50 μm, and was irradiated with 15 mW of ultraviolet light for 30 seconds in a nitrogen atmosphere to obtain a semi-cured photopolymerizable composition.

The photopolymerizable composition side of the polyester film on which the obtained semi-cured photopolymerizable composition is formed,
Heat shrinkage at 100 ° C is 67, 74, 3 respectively
A pressure-sensitive adhesive layer was obtained by superposing it on a polyester film (Space Clean, manufactured by Toyobo Co., Ltd.) having a thickness of 5% and having a thickness of 40 μm, and again irradiating it with ultraviolet rays for 120 seconds from the side of the peelable and transparent polyester film to completely polymerize it. To form an adhesive tape. These were designated as Example 1, Example 2 and Example 3, respectively.

(Example 4) 82 parts of 2-ethylhexyl acrylate, 8 parts of N-vinylpyrrolidone, 10 parts of carboxyethyl acrylate, 15 parts of coumaroindene resin (Escrystal A-120S manufactured by Nippon Steel Chemical Co., Ltd.), hexanediol diacrylate 0 0.06 part, 2.5 parts of acrylic rubber and 1.3 parts of 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (Dalocure 2959, manufactured by Merck). Heat shrinkage at 100 ° C is 74%, 40μ
An m-thick polyester film (manufactured by Toyobo Co., Ltd., Space Clean) was applied to one side with a thickness of 50 μm and irradiated with 15 mW of ultraviolet rays for 120 seconds in a nitrogen atmosphere to form an adhesive layer, thereby obtaining an adhesive tape.

Example 5 Instead of the heat-shrinkable polyester film used in Example 1, the heat-shrinkage rate was 70.
%, A pressure-sensitive adhesive tape was obtained in exactly the same manner as in Example 1 except that a woven fabric sheet of polyvinyl chloride fiber having a thickness of 40 μm (manufactured by Teijin Ltd., Teviron fiber) was used.

(Example 6) Example 1 was repeated except that 10 parts of a heat-expandable resin (Microsphere F-30, manufactured by Matsumoto Yushi Co., Ltd.) was added to the photopolymerizable composition used in Example 1. Similarly, an adhesive tape was obtained.

(Comparative Example 1) Acrylic adhesive solution (SK
Dyne 1700, manufactured by Soken Kagaku Co., Ltd.) was applied to one side of the heat-shrinkable polyester film used in Example 1 to obtain 60.
The adhesive tape was obtained by forming a 50 μm pressure-sensitive adhesive layer by heating and drying at 20 ° C. for 20 minutes.

Comparative Example 2 100 parts of an acrylic adhesive solution (SKDyne 1700 manufactured by Soken Chemical Co., Ltd.) and 10 parts of a heat-expandable resin (Microsphere F-30 manufactured by Matsumoto Yushi Co., Ltd.)
Part of toluene adhesive solution was applied to one side of the heat-shrinkable polyester film used in Example 1, and 60
The adhesive tape was obtained by forming a 50 μm pressure-sensitive adhesive layer by heating and drying at 20 ° C. for 20 minutes.

(Comparative Example 3) An adhesive tape was prepared in the same manner as in Comparative Example 2 except that 30 parts of the heat-expandable resin (Microsphere F-30 manufactured by Matsumoto Yushi Co., Ltd.) was used in Comparative Example 2. Obtained. Each of the pressure-sensitive adhesive tapes obtained in the above Examples and Comparative Examples was cut into 20 × 100 mm square pieces, attached to an ABS resin plate, and pressure-bonded with a 2 kg roller. Then, the adhesive force after being left at room temperature for 30 minutes, and the 180 ° direction peeling force (g / 20 m from the ABS resin plate after being left at room temperature for 30 minutes and further heated in an oven at 100 ° C. for 10 minutes
m) was measured according to JIS-Z0237, and the initial adhesive strength and the adhesive strength after heat treatment were evaluated.

Further, as another evaluation method of the removability,
Each of the adhesive tapes obtained in Examples and Comparative Examples was attached to an ABS resin plate and pressure-bonded with a 2 kg roller, and then the adhesive tape was placed in an oven at 100 ° C. for 10 minutes, and the self-weight drop property was exhibited. Evaluation was made, and those that fell were rated as ◯, and those that did not fall as x. The above evaluation results are shown in Table 1.

[0036]

[Table 1]

[0037]

[Effect] The adhesive tape obtained by the method of the present invention has a sufficiently high initial adhesive strength to an adherend, and the adhesive tape can be sufficiently reduced by heat treatment at 100 ° C.
A removable adhesive tape can be obtained. Further, according to the method of the present invention, the time required to form the pressure-sensitive adhesive layer is much shorter than that in the case of using a normal solvent-type pressure-sensitive adhesive, so that the productivity is also high. Further, when the pressure-sensitive adhesive tape is manufactured, heat is not applied to form the pressure-sensitive adhesive layer, so that the base material can be directly coated. Therefore, it is possible to manufacture a removable adhesive tape having high productivity.

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Claims (1)

[Claims] 1. An uncured or semi-cured acrylate monomer, a vinyl monomer copolymerizable with an acrylate monomer, a tackifying resin, on at least one surface of a synthetic resin film or fibrous sheet having a heat shrinkage rate of 5 to 80%.
A method for producing an adhesive tape, which comprises irradiating with light after applying a photopolymerizable composition comprising a crosslinking agent and a photopolymerization initiator.