JPH0421715B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to an improved method of manufacturing adhesive sheets that does not require a separate release paper. (Prior art) Conventionally, adhesive sheets have been manufactured with release paper overlaid on the adhesive surface to prevent them from adhering to each other when not in use and to prevent dirt and dust from adhering to the adhesive surface. It is in circulation. However, as mentioned above, the release paper used for this purpose protects the adhesive surface until the adhesive sheet is used, and therefore it is removed and discarded when the adhesive sheet is used. The bulk of the sheet increases,
Moreover, it is very disadvantageous from the standpoint of resource conservation. Therefore, for example, if you partially provide an adhesive layer on both ends of a sheet-like base material, provide a release layer on the part where no adhesive layer is provided, and fold both ends, you can use a separate release paper. The adhesive surface of the adhesive sheet can be protected without using it. However, in order to manufacture the above-mentioned pressure-sensitive adhesive sheet, it is necessary to partially provide a release layer on one side of the sheet-like base material, and then apply an adhesive layer only to the areas where the release layer is not provided. In order to ensure the registration of the layers, it is necessary to add a method such as coloring the release layer, and even if this method is used, it is difficult to provide the adhesive layer very close to the release layer. It is. The inventors of the present invention have repeatedly conducted research in order to eliminate the drawbacks of the above-mentioned conventional technologies. As a result, the adhesive strength between the release layer and the adhesive layer is low in a typical silicone-based release layer with an adhesive layer. Although not sufficient and cannot be used as an adhesive sheet, vinyl groups, mercapto groups,
A release layer is formed using a silicone compound having a methacrylic group or an acrylic group and a composition containing such a compound, and then an adhesive containing a (meth)acrylic acid ester monomer is placed on the release layer. By partially applying the agent composition and irradiating it with ionizing radiation, the adhesive strength between the adhesive layer and the release layer is improved, and as a result, it can be used satisfactorily as an adhesive sheet even though it has a configuration with an adhesive layer on the release layer. It has been found that what is possible can be obtained. The present invention has been made based on the above findings, and the present invention provides at least one type of silicone compound having a vinyl group, a mercapto group, a methacrylic group, or an acrylic group on at least one surface of a sheet-like base material. and, with the coated surface in an uncured or semi-cured state, a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester monomer is partially coated on the coated surface, and then, The gist of this is a method for producing a pressure-sensitive adhesive sheet, which is characterized by irradiation with ionizing radiation. (Structure of the present invention) The present invention will be described in detail below. First, various types of sheet-like substrates can be used in the present invention, including papers such as ledger paper, thin paper, condenser paper, high-quality paper, art paper, coated paper, and paperboard;
Polyethylene film, polypropylene film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, polyethylene terephthalate film, polycarbonate film, nylon film, polystyrene film, ethylene vinyl acetate copolymer film, ethylene vinyl alcohol copolymer film, ionomer , cellulose diacetate, cellulose triacetate, plastic films or sheets such as polysulfone film, polyimide film, aluminum, copper, tin, gold,
Metal foils or sheets made of silver, lead, iron, stainless steel, etc., non-woven fabrics or spunbond fabrics such as rayon fibers, polyester fibers, non-woven fabrics or woven fabrics of glass fibers, woven fabrics of natural or synthetic fibers, mineral fibers such as asbestos or rock wool, etc. A sheet, a wood sheet made by thinly slicing wood, a composite sheet of any of the above-mentioned materials, etc. can be used. Next, the composition used to form the release layer contains the following silicone compound; An organopolysiloxane having at least one organopolysiloxane unit represented by the following general formula (a). However, X represents the above-mentioned crosslinking group, R ¹ represents a substituted or unsubstituted saturated monovalent hydrocarbon group having no crosslinking group, and the subscript a represents 0, 1, or 2. Alternatively, the silicone compound used in the present invention refers to a copolymer consisting of the above general formula (a) and a siloxane unit represented by the following general formula (b). However, R ² is the same as R ¹ , and the subscript b is 0, 1,
2 or 3. Specific examples of the siloxane unit represented by the above general formula (b) include dimethylsiloxane units, methylphenylsiloxane units, methyltrifluoropropylsiloxane units, and methylhydrodienesiloxane units. The above silicone compounds can be used alone or in combination of two or more. Furthermore, the silicone compound having the above-mentioned functional group can be mixed into a conventional solution-type silicone release agent. The silicone compound can be applied by a known roll coating method or gravure roll coating method. The coating amount is preferably 0.1 to 10 g/m ² , but from an economic standpoint, 0.1 to 3.0 g/m ² is preferable.
While the silicone compound composition coated on the sheet-like base material is in an uncured or semi-cured state, a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester monomer is applied onto the silicone layer in the form of a stripe. Partially apply to the shape of. While the silicone compound composition is in an uncured or semi-cured state, a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester monomer is partially applied onto the silicone layer in the form of a stripe or the like. The reason why the adhesive is applied while the silicone compound composition is uncured or semi-cured is that by irradiating it with ionizing radiation in the next step, the layer of the silicone compound composition and the adhesive layer bond together. This is because the strength is improved, and the term "uncured" or "semi-cured" refers to a state in which some of the functional groups of the silicone compound described above remain in the layer of the silicone compound composition. In view of the manufacturing process, it is preferable that the material be in a state where it can be felt that it is hardened to the touch. Next, a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester monomer will be explained. (meta)
The acrylic acid ester monomer is used to increase the adhesive strength between the silicone compound composition layer and the pressure-sensitive adhesive layer. (Meth)acrylic acid ester monomers used for this purpose include:
For example, monomers represented by the general formula CH ₂ = CHCOOR ³ (where R ³ is an alkyl group having 2 to 14 carbon atoms), general formula

[Formula] (where R ⁴ is H, or an alkyl group or phenyl group having 1 or more carbon atoms, R ⁵ and R ⁶ are H,
or an alkyl group having 1 or more carbon atoms, n is an integer of 1 or more), 2-hydroxy-
3-phenoxypropyl acrylate, acryloyloxyethyl monosuccinate, acryloyloxyethyl monophthalate, or 2-hydroxy-3-phenoxypropyl acrylate, general formula (However, R ⁷ is H or an alkyl group having 1 or more carbon atoms, n is an integer of 1 or more, and R _U8 is an alkyl group having 1 or more carbon atoms), as well as ethylene glycol diacrylate, polyethylene glycol Examples include diacrylate, hexanediol diacrylate, trimethylolpropane triacrylate, and methacrylate monomers corresponding to these acrylate monomers. The adhesive composition containing the above (meth)acrylic acid ester monomer can be made by mixing the above monomer with a conventional solution type adhesive or hot melt type adhesive, or it can be made by mixing the above monomer with a conventional solution type adhesive or hot melt type adhesive, or a butyl acrylate copolymer or a butyl acrylate copolymer. A solvent-free adhesive prepared by dissolving 2-ethylhexyl acrylate copolymer in the above monomer can be used. (meta)
The acrylic acid ester monomer is contained in the adhesive composition in an amount of 1.0 to 80% by weight as a solid content, preferably 10 to 50% by weight.
Preferably, it contains % by weight. At less than 1.0% by weight,
In the resulting pressure-sensitive adhesive sheet, the adhesive force between the release layer made of the silicone compound composition and the pressure-sensitive adhesive layer is insufficient, and if the amount exceeds 80% by weight, the cohesive force and adhesion of the pressure-sensitive adhesive will deteriorate even when irradiated with ionizing radiation. Run short. The adhesive composition may be prepared by mixing a photosensitizer that generates radicals upon irradiation with ultraviolet rays or a polymerization inhibitor for improving storage stability. Various coating methods can be used to apply the adhesive composition, such as hot melt coating using a fountain coater, various roll coatings, gravure coating, screen coating, and other known methods. A coating method can be selected depending on the viscosity. The amount of adhesive applied is preferably 10 to 50 g/m ² , which is approximately the same amount as that for ordinary labels and tapes. After application, the surface to which the adhesive composition is applied is irradiated with ionizing radiation. As the ionizing radiation, for example, an electron beam can be used, and it is possible to use electron beams from various electron beam accelerators such as Kotscroft-Walton type, Van de Graaff type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type. emitted, 50-1000KeV,
Preferably, an electron beam with an energy in the range of 100 to 300 KeV is used. Continuous crosslinking of the coating layer is possible by continuously running the sheet-like substrate coated with the silicone compound composition and adhesive composition and irradiating it with a continuous curtain-shaped electron beam from a linear filament. becomes. The dose of electron beam is usually 0.5 to 20 Mrad, preferably 3 to 20 Mrad.
It is 20 Mrad. Further, the above electron beam irradiation is preferably performed in an atmosphere of an inert gas such as nitrogen. Alternatively, ultraviolet rays may be used instead of electron beams, and ultra-high pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, carbon arcs, xenon arcs, metal halide lamps, etc. can be used as the ultraviolet ray source. When ultraviolet rays are used as ionizing radiation, a benzophenone-based or benzoin ether-based ultraviolet sensitizer is added to the adhesive composition to be cured. (Effects) According to the above method of the present invention, even if the adhesive layer is laminated on the release layer, the adhesive force between both layers is improved by irradiation with ionizing radiation, and therefore the adhesive layer By folding the adhesive sheet so that the release side (the part without the adhesive layer) of the adhesive sheet touches the top of the adhesive sheet, the adhesive sheet can be protected without using a separate release paper. In addition, the resulting adhesive sheet has an adhesive strength between the adhesive layer and the release layer in the part that is bonded by folding, which is almost the same as the adhesive strength between the normal adhesive layer and a separate release layer. Therefore, when using the adhesive sheet, the folded portion can be easily peeled off to expose the adhesive layer, and the adhesive sheet can be used in the same way as a normal adhesive sheet. Example 1 One side of a biaxially stretched polypropylene film with a thickness of 30μ was subjected to corona discharge treatment, and then a silicone release agent having a methacrylic group (methacrylic group-containing silicone; manufactured by Shin-Etsu Chemical Co., Ltd.) was applied at a coating amount of 0.8 g/m ²
Apply the electron beam evenly so that the
Irradiated. Next, an electron beam curable adhesive consisting of 60 parts by weight of polybutyl acrylate (average molecular weight in terms of styrene of 100,000), 20 parts by weight of lauryl acrylate, and 20 parts by weight of 2hydroxy-3-phenoxypropyl acrylate was hot melted. It was coated in stripes with a coater (Park Coater; manufactured by Yuri Roll Machinery Co., Ltd.) at a coating amount of 30 g/m ² , and irradiated with an electron beam of 8 Mrad at an accelerating voltage of 175 kV to obtain a pressure-sensitive adhesive sheet. A book cover was made by bending the obtained adhesive sheet so that the adhesive processed surface and the silicone release layer surface were in contact with each other. This book cover was able to be peeled off at the folded part, coated on the cover of the book, and then adhered using the adhesive surface. Example 2 A methacrylic group-containing silicone compound (manufactured by Shin-Etsu Chemical) was fixed on one side of a polyethylene terephthalate film (manufactured by Toray Industries, Ltd., Q-27, thickness 25μ) in a solution-type release agent (KS772, manufactured by Shin-Etsu Chemical, silicone release agent). The silicone release agent was mixed to contain 10% by weight as a mold component, and the solid content was 1.
Apply it evenly so that it is g/m ² , dry it, and then
It was left at a temperature of 100°C for 2 minutes to heat cure. Next, acrylic solution-based adhesive (Olivine
A pressure-sensitive adhesive composition containing 10% by weight of 1,6-hexanediol diacrylate as solids was mixed into a polyethylene terephthalate film coated with the silicone release agent described above. The silicone release agent layer was roll-coated in stripes using a convex roll so that the coating amount was 20 g/ ^m2 , and after drying the solvent, an electron beam was applied in a nitrogen gas atmosphere.
An adhesive sheet was obtained by irradiating with 5 Mrad. The adhesive force between the adhesive layer and the adhesive layer of the obtained adhesive sheet (according to JIS Z0237) was 800 g/25 mm, which was good for practical use. Further, the peel strength between the silicone layer and the adhesive layer was 1020 g/25 mm. This label was suitable as a cover label for display labels. Comparative Example 1 A solution-type release agent (KS772, manufactured by Shin-Etsu Chemical Co., Ltd.) was coated and cured in the same manner as in Example 2 without adding methacrylic group-containing silicone, and an acrylic solution-type adhesive (Olivine BPS2411, manufactured by Toyo Ink) was applied and cured. ) was coated on the silicone layer and dried without adding 1,6-hexanediol diacrylate. This label had no adhesiveness between the adhesive layer and the silicone layer, and could not be used as a label. Example 3 Consisting of 95 mol% of dimethylsiloxane units and 5 mol% of mercaptopropylmethylsiloxane units, both ends of the molecular chain are blocked with trimethylsilyl groups.
It consists of 20 parts by weight of a mercapto group-containing organopolysiloxane having a viscosity of about 200 centistokes at 25°C, 98 mol% of dimethylsiloxane units and 2 mol% of vinylmethylsiloxane units, both ends of the molecular chain are blocked with trimethylsilyl groups, A silicone compound composition consisting of 100 parts by weight of a vinyl group-containing organopolysiloxane having a viscosity of about 1000 centistokes at 25°C was applied to a corona discharge treated biaxially stretched polypropylene film (40μ) in an amount of 0.5 g/m. ^2. Evenly coated. Next, it was irradiated with an electron beam of 1 Mrad in a nitrogen gas atmosphere to bring it into a semi-cured state. Next, 60 parts by weight of butyl polyacrylate (average molecular weight in terms of styrene: 100,000), 3 parts by weight of diacetone acrylamide, 10 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, and 27 parts by weight of lauryl acrylate. The coating amount of the adhesive composition on the semi-cured silicone layer is 20 g/
It was coated in stripes so that the area was 2 m ² and irradiated with an electron beam of 10 Mrad in a nitrogen gas atmosphere. The adhesive strength (JISZ0237) of the obtained label was 600g/25mm, and the peel strength between the silicone layer and the adhesive layer was 600g/25mm.
g/25mm. This label was useful as a cover film for the delivery pack. Example 4 97 mol% dimethylsiloxane units and 3 mol% γ-brisidoxypropylmethylsiloxane units
organopolysiloxane, in which both ends of the molecular chain are blocked with trimethylsilyl groups, and γ
- Acrylic group-containing organopolysiloxane obtained by adding glycidoxypropylmethylsiloxane and equimolar amount of acrylic acid is contained in a solution-type silicone release agent (KS772, manufactured by Shin-Etsu Chemical) in a solid content of 10% by weight. The silicone solution mixed in the above manner was applied uniformly to the polyethylene side of the polyethylene-coated paper at a concentration of 0.8 g/m ² and dried by blowing hot air at a temperature of 80°C. Next, 70 parts by weight of polybutyl acrylate (average molecular weight in terms of styrene: 100,000), 10 parts by weight of Aronix M113 (manufactured by Toagosei Chemical Co., Ltd., acrylic acid ester monomer), 5 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate, A pressure-sensitive adhesive composition consisting of 5 parts by weight of 1,6-hexanediol diacrylate, 5 parts by weight of benzophenone, and 5 parts by weight of ethyl-4-dimethylaminobenzoate is applied in a striped manner so that the coating amount of the area is 15 g/m ² It was applied like this. The adhesive composition was then cured by irradiation with ultraviolet rays. The adhesive strength (JISZ0237) of the obtained pressure-sensitive adhesive sheet was 300 g/25 mm. This sheet was useful as a book cover.

Claims (1)

[Claims] 1 A composition containing one or more silicone compounds having a vinyl group, a mercapto group, a methacrylic group, or an acrylic group is applied to at least one surface of a sheet-like base material, and the applied surface is uncured or semi-cured. 1. A method for producing a pressure-sensitive adhesive sheet, comprising partially applying a pressure-sensitive adhesive composition containing a (meth)acrylic acid ester monomer to the coated surface, and then irradiating it with ionizing radiation.