JP2009029916A - Self-adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-adhesive sheet free from the occurrence of a blurred print even in the case of printing on the self-adhesive sheet subjected to a cut work to expose the surface of the releasing layer by a dry electrophotographic method and free from the occurrence of the simultaneous peeling of a label in the case of processing the sheet in a high-speed zone. <P>SOLUTION: The self-adhesive sheet comprises successively laminating a substrate, a self-adhesive layer, a releasing layer and a releasing paper, wherein the releasing layer is formed from a mixture of a silicone dissolved in a solvent and a silicone, and the silicone dissolved in a solvent has a methyl group and a vinyl group on the side chain and the ratio of the vinyl group to the methyl group is 6-10%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive sheet, and particularly to a pressure-sensitive adhesive sheet that can be used in a non-impact printer typified by an electrophotographic method, can be suitably used as a label sheet or a delivery slip, and is further partially raised. .

  In recent years, with the spread of electrophotographic printers and high-speed printing, cases related to slip-related products such as delivery slips are increasing in electrophotographic printers. At the same time, personalized mailing labels have become widespread.

  With widespread use, various forms of labels such as delivery slips and address labels are being sold in pursuit of ease of use. Among them, when printing on the adhesive sheet by dry electrophotographic method, etc., there is a problem that the adhesive heats around 180 ° C. due to the influence of the heat roll in the printing part, and the adhesive protrudes from the adhesive sheet due to the softening of the adhesive. Therefore, in order to avoid this, there is a method in which the upper part of the pressure-sensitive adhesive sheet is lifted up from the pressure-sensitive adhesive layer. In addition, address labels etc. mainly consist of a plurality of imprinted labels on a sheet such as A4. Arbitrarily devised so that each label can be easily removed by raising the periphery of the sheet so that it can be easily removed. Has been made.

  In this case, it is known that a silicone resin such as solvent-type silicone or solvent-free silicone is used as the release agent provided on the pressure-sensitive adhesive layer so that the release paper is easily peeled off from the pressure-sensitive adhesive layer (Patent Document 1). See). However, when the adhesive sheet that has been punched out in a state where the surface of the release agent layer made of solvent-based silicone is printed by a dry electrophotographic method, the silicone film formed on the release base paper comes into contact with the photosensitive drum, A part of the silicone film may be finely shaved and adhere to the photosensitive drum, resulting in printing stains.

  Solvent-based silicones are designed with a high molecular weight of 500,000 to 1,200,000 in order to obtain a stable cured film. Therefore, the viscosity is as high as 4,000 to 5,000 cps at a solid content of 30%. Due to poor workability, it is diluted with a solvent such as toluene. In general, the side chain of the base polymer has a methyl group or a vinyl group. In order to increase the strength of the cured film, it is necessary to increase the crosslink density of the silicone. Therefore, a countermeasure can be taken by using a low molecular weight, but conversely, coating cannot be performed due to a decrease in viscosity and an increase in the solid content.

On the other hand, solventless silicone should be applied to the release base paper without using a solvent, the silicone coating amount must be uniformly coated with 0.5g ^/ m ² ~1.2g / m 2 For this reason, it is necessary to set the viscosity to at least about 1,000 or less, and it is necessary to design with a low molecular weight of about 6,000 as compared with solvent type silicone. Therefore, it is necessary to introduce a larger number of functional groups such as vinyl groups and SiH groups than solvent type silicone, and the peeling force in the low speed region tends to be heavy and the peeling force in the high speed region tends to be light. For this reason, it is easy for labels to rise together in the dregs raising process during printing in a high-speed region. In order not to cause the co-raising, the tensile strength, tear strength, and rigidity of the support may be specified, but the selectivity of the base material that can be used becomes narrow.
JP-A-11-293596

  In view of the above situation, the present invention has a coating strength that does not cause printing stains even when a pressure sensitive adhesive sheet that has been punched into a state where the release agent layer is exposed is printed by a dry electrophotographic method. It is an object of the present invention to provide a pressure-sensitive adhesive sheet having a peeling force that does not cause the labels to rise together when the sheet is processed in a high-speed region.

  The present invention is a pressure-sensitive adhesive sheet obtained by sequentially laminating a support, a pressure-sensitive adhesive layer, a release agent layer, and a release base paper, and the release agent layer is formed from a mixture of solvent-based silicone and solvent-free silicone. The solvent-based silicone is a pressure-sensitive adhesive sheet having a methyl group and a vinyl group in a side chain, and a ratio of the vinyl group to the methyl group is 6 to 10 mol%. . The mixing ratio of the solvent-based silicone and the solvent-free silicone in the release agent layer is preferably 90:10 to 70:30 in terms of solid weight ratio.

  When the pressure sensitive adhesive sheet of the present invention is printed by a dry electrophotographic method, the pressure sensitive adhesive sheet that has been punched into a state where the release agent layer is exposed to the surface, even when the silicone film of the release agent layer contacts the photosensitive drum, Part of it is finely scraped and does not adhere to the photosensitive drum, and it can be used without causing printing stains and with no peeling even when printing in the high-speed region. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an adhesive sheet according to an embodiment of the present invention. The pressure-sensitive adhesive sheet 1 includes a support 2, a pressure-sensitive adhesive layer 3 formed on one surface of the support 2, and a release agent bonded to a surface on a different side from the surface of the pressure-sensitive adhesive layer 3 on the support 2 side. And a release base paper 5 coated with the layer 4.

2 and 3 are a typical cross-sectional view and a top view when the end portion is scraped up in the embodiment of FIG. 1, and reference numeral 6 is a scrap lift portion.
(Support)
The support 2 is not particularly limited, but any recording paper can be appropriately selected from those conventionally used as recording paper.

Specific examples include coated paper such as high-quality paper, cast-coated paper, and art-coated paper, fine-coated paper, and the like, and a pseudo-adhesive layer on the back surface of the support for pressure-sensitive adhesive sheets used for delivery slips. A base material formed of paper or a resin film on the pressure-sensitive adhesive surface side of the pseudo-adhesive layer is used.
(Adhesive)
The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 3 is not particularly limited, but an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive such as natural rubber or synthetic rubber, and a pressure-sensitive adhesive such as a silicone-based pressure-sensitive adhesive can be arbitrarily selected and used. can do. Among these, it is preferable to use an acrylic pressure-sensitive adhesive having high adhesive strength and excellent weather resistance, flexibility, and heat resistance.

  The acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive using an acrylic polymer which is mainly composed of alkyl (meth) acrylate and copolymerized with a polar monomer. The (meth) acrylic acid alkyl ester is an acrylic acid alkyl ester or a methacrylic acid alkyl ester, and is not particularly limited, but is methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate. , Isononyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl acrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate and the like. Polar monomers that copolymerize with (meth) acrylic acid alkyl esters are, for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate, hydroxyalkyl methacrylate, which are hydroxyalkyl acrylates. Hydroxyl group-containing monomers such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate, unsaturated aliphatic carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid, N- Nitrogen-containing monomers such as vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate Epoxy group-containing monomers such as bets and the like. The polar monomer acts as a crosslinking point when the acrylic polymer is crosslinked using a crosslinking agent.

In addition, various additives such as a lubricant, a plasticizer, an antiaging agent, and a tackifier may be blended as long as the characteristics are not impaired.
(Adhesive coating method)
As a method for applying the adhesive, for example, a gravure printing method, a spray method, a roll coater method, an air knife coater method, a bar coater method, a comma coater method, a die coater method, and the like are coated and dried on release paper. Then, after the pressure-sensitive adhesive layer is formed, it is produced by laminating it with a support.
(paint remover)
The release agent used for the release agent layer 4 is a mixture of solvent-based silicone and solvent-free silicone, and exhibits excellent releasability for various adhesives.

  The solvent-based silicone is designed with a high molecular weight of 500,000 to 1,200,000 in order to obtain a cured film. Therefore, the viscosity is as high as 4,000 to 5,000 cps at a solid content of 30%, and the coating is applied. Diluted with toluene, MEK, etc. The base polymer generally has a methyl group or a vinyl group in the side chain. In order to increase the strength of the cured film, it is necessary to increase the crosslink density of silicone, and the crosslink density depends on the content of vinyl groups in the side chain.

  In the present invention, a solvent-based silicone having a methyl group and a vinyl group in the side chain and a ratio of the vinyl group to the methyl group of 6 to 10 mol% is used as the solvent-based silicone. When the vinyl group content is in the range of 6 mol% to 10 mol% with respect to the methyl group content, the balance between the crosslink density, that is, the film strength and the peeling force is best. More preferably, it is 7-9 mol%. If it is less than 6 mol%, the film strength is weaker, the peel force in the low speed region is lighter, and the peel force in the high speed region is heavier than 6 mol% or more solvent-based silicone. In addition, about the ratio of a methyl group and a vinyl group, it can confirm by the gas chromatograph-mass spectrum (GC / MS) method. Examples of the solvent-based silicone that can be used in the present invention include the product name KS3651 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  By using such a solvent-based silicone in combination with a solvent-free silicone, it is possible to maintain a film strength sufficient to prevent the silicone from being removed by the drum when it contacts the photosensitive drum. Solventless silicone is a silicone that can be applied without using a diluting solvent such as a solvent, has a molecular weight of at least about 500 to 10,000, and a vinyl group content of 4 mol% to a methyl group content. The range is preferably 10 mol%. Although the kind is not specifically limited, Product name KNS-320A (made by Shin-Etsu Chemical Co., Ltd.), KNS316 (made by Shin-Etsu Chemical Co., Ltd.), etc. can be mentioned. In addition, when solvent-free silicone is used alone, there is a tendency that peeling in a high-speed region tends to be light, and there is a tendency for labels to rise together when dregs are raised during printing processing. Thus, it is possible to prevent the labels from rising together.

  For crosslinking of silicone, a catalyst is used, but a platinum-based catalyst is preferable. Chloroplatinic acid such as chloroplatinic acid and chloroplatinic acid, alcohol compounds of chloroplatinic acid, aldehyde compounds or chloroplatinic acid and Complexes with various olefins are used. The catalyst addition amount is preferably 0.1 to 10% by weight, more preferably 0.5 to 5.0% by weight.

  The above-mentioned solvent-based silicone and solvent-free silicone are mixed, and an appropriate amount of each catalyst is added and used, so that the film strength can be increased and the peel strength in a high-speed region can be kept high.

  In the release agent layer in the present invention, the mixing ratio of the solvent-based silicone and the solvent-free silicone is preferably 90:10 to 70:30, more preferably 80:20 to 70:30 in terms of solid weight ratio. preferable. If the ratio of solvent-free silicone is low, the film strength that can exert the effect cannot be obtained, and if the ratio is high, the peeling force in the high-speed region is low, and there is a possibility of causing a co-up during the dregs raising. .

  The film strength was measured with a tensile tester according to JIS P 8113 of a silicone film formed under the curing conditions of 120 ° C. (dry) × 20 minutes with a width of 15 mm, a length of 200 mm, and a thickness of 3 mm. The breaking strength is preferably 800 to 1,700 g / 15 mm, more preferably 1,200 to 1,700 g / 15 mm.

The peeling force in the high speed region is preferably 45 to 95 g / 50 mm, and more preferably 45 to 80 g / 50 mm. At this time, if the peeling force exceeds 95 g / 50 mm, there is a possibility that the residue is broken when the residue is raised.
(Peeling base paper)
The release base paper 5 is not particularly limited, and examples thereof include natural paper such as high-quality paper, coated paper such as cast coated paper and art coated paper, and fine coated paper, glassine paper, kraft paper, and other polyester. A synthetic resin film or the like can be used.

When paper is used as the release base paper, it is preferable that it is coated with a material that can be silicone-sealed, such as clay coating, and more preferably has a density in the range of 0.8 to 1.0 g / cm ³ .
(Release coating method)
As a coating method of the release agent, a coating method using a gravure coater, a bar coater, a 5-roll coater or the like is appropriately used, and the adjusted release agent has a solid content weight of 0.1 to 0.2 g / m ² , Preferably, it is applied so as to be about 0.5 to 1.2 g / m ^2, and a release layer can be provided by thermosetting.

Hereinafter, although this invention is demonstrated concretely using the adhesive sheet of Examples 1-9 and Comparative Examples 1-11, this invention is not limited to these Examples.
(Preparation of silicone)
In Examples 1 to 5, a solvent-based silicone (product name: KS3651: manufactured by Shin-Etsu Chemical Co., Ltd.) having a solid content solution of 30% in which the vinyl group content of the base polymer is 8 mol% with respect to the methyl group content; Solvent-free silicone (product name KNS-320A: manufactured by Shin-Etsu Chemical Co., Ltd.) is mixed at a solid weight ratio shown in Table 1, and toluene as a diluent solvent is added so that the solid content is 10%. A platinum chloride catalyst (product name: CAT-PL50T: manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a catalyst in an amount of 4% by weight and stirred for 20 minutes to prepare a silicone solution.

  In Examples 6 to 7, the solvent-based silicones of the test products A to D in which the vinyl group content with respect to the methyl group content of the base polymer was changed to mol% described in Table 1 and the solventless silicone were mixed into 80:20 solids. A silicone solution was prepared in the same manner as in Examples 1 to 5 below.

  In Comparative Example 1, 1 wt% of the platinum chloride catalyst was added to the solvent-based silicone, and toluene as a diluting solvent was added so that the solid content was 10%, followed by stirring for 20 minutes to prepare a silicone solution. did.

  In Comparative Examples 2 to 8, a solvent-based silicone (product name: KS776L: manufactured by Shin-Etsu Chemical Co., Ltd.) having a solid content solution of 30% in which the vinyl group content of the base polymer is 4 mol% with respect to the methyl group content. used. The solventless silicone to be mixed and the preparation of each were carried out in the same manner as in Examples 1 to 5. However, the mixing ratio was as shown in Table 1, and a silicone solution was prepared in the same manner.

  In Comparative Examples 9 to 10, the solvent-based silicones of the test products E and F in which the vinyl group content with respect to the methyl group content of the base polymer was changed to mol% described in Table 1 and the solventless silicone were 80:20 solids A silicone solution was prepared by the same method.

In Comparative Example 11, 3% by weight of the platinum chloride catalyst was added to the solventless silicone, and the mixture was stirred for 20 minutes.
(Creation of release paper)
The prepared silicone was applied to a release base paper (product name C46: manufactured by Daio Paper Co., Ltd.) with a gravure coater so that the solid content weight was 0.8 g / m ^2, and dried in an environment of 140 ° C. for 1 minute. A release paper was prepared.
(Creation of adhesive sheet)
On the silicone layer of the release paper prepared as described above, an acrylic emulsion adhesive (product name: AT1202: manufactured by Seiden Chemical Co., Ltd.) was applied so as to have a solid weight of 20 g / m ^2, and copy paper ( Light PPC (manufactured by Daio Paper Co., Ltd.) was bonded to prepare an adhesive sheet.
(Evaluation method and evaluation)
1. Evaluation of Silicone Film Strength A silicone film having a width of 15 mm, a length of 200 mm and a thickness of 3 mm is formed from the prepared silicone solution under curing conditions of 120 ° C. (dry) × 20 minutes. The formed silicone film is measured with a tensile tester (Shimadzu Corporation) according to JIS P8113.
2. Evaluation of peel strength in high speed region (100 m / min) The prepared pressure-sensitive adhesive sheet is cut into a width of 50 mm and a length of 300 m and left in an environment of 23 ° C. and 50% for 2 hours or more. Thereafter, the peel strength when the release paper is peeled off at a speed of 100 m / min with a high-speed tensile tester (manufactured by Tester Sangyo) is confirmed.
3. Co-up confirmation test Roll produced adhesive sheet 1000m was punched at 100m / min using Miyakoshi offset rotary press to create A4 cut plate with 6-sided label and 2mm scraping process around the label. And cutting.
○: No label rise.
X: There is co-up of the label.
4). Print dirt evaluation Printer name: Docu Print 401 and Docu Center 401 (both manufactured by Fuji Xerox) were used. The prepared A4 plate adhesive sheet was continuously passed through 100 sheets, and the presence or absence of printing stains was confirmed. Printing stains occur at intervals around the circumference of the photosensitive drum.
○: No printing stains ×: Printing stains

表１より、ビニル基含有率が６〜１０モル％の溶剤系シリコーンと無溶剤系シリコーンとの混合品のシリコーンを使用した場合には、印字汚れの発生がなく、かつ高速領域での剥離力が４５〜９５ｇ／５０ｍｍでラベルの共上がりが発生しない粘着シートが得られることがわかる。

From Table 1, when using a mixed silicone of solvent-based silicone and solvent-free silicone with a vinyl group content of 6 to 10 mol%, there is no occurrence of printing stains and peel strength in the high-speed region. Is 45 to 95 g / 50 mm, it can be seen that a pressure-sensitive adhesive sheet in which the label does not rise together is obtained.

Sectional drawing of the adhesive sheet which is one aspect | mode of this invention (it is not scraped up) Cross-sectional view of a pressure-sensitive adhesive sheet that is one embodiment of the present invention The top view of the pressure-sensitive adhesive sheet that has been scraped up according to one embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Adhesive sheet 2 Support body 3 Adhesive layer 4 Release agent layer 5 Release base paper 6 Waste part

Claims (2)

A pressure-sensitive adhesive sheet obtained by sequentially laminating a support, a pressure-sensitive adhesive layer, a release agent layer, and a release base paper,
The release agent layer is formed from a mixture of solvent-based silicone and solvent-free silicone,
The pressure-sensitive adhesive sheet, wherein the solvent-based silicone has a methyl group and a vinyl group in a side chain, and a ratio of the vinyl group to the methyl group is 6 to 10 mol%.   The pressure-sensitive adhesive sheet according to claim 1, wherein a mixing ratio of the solvent-based silicone and the solvent-free silicone in the release agent layer is 90:10 to 70:30 in terms of solid weight ratio.

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