JP4505583B2 - Substrate-less double-sided adhesive tape used for die-cutting - Google Patents

Description

  The present invention relates to a base material-less double-sided pressure-sensitive adhesive tape having a peelable pressure-sensitive adhesive layer on a release sheet and a base material-less double-sided pressure-sensitive adhesive sheet. The tape is referred to as having a narrower width than the sheet, and the following description will be made assuming that there is no functional difference between the two.

Conventionally, when two flat members facing each other in any field are bonded together, it is excellent in handleability, workability, bonding adhesiveness, etc., so double-sided adhesive with adhesive applied on both sides of the substrate Tape is widely used. In particular, in recent years, in display units of personal computer display units such as LCDs, display units of portable information terminals such as mobile phones, other liquid crystal panels, panel types such as organic EL panels, PDP panels, or flat panel type display devices, In addition, various counter optical members, including a touch panel, are provided on the display units provided in telephones, copiers, facsimiles, printers, advertisement / information display plates, etc., and these are transparent to bond and bond them to the frame. Double-sided adhesive tape is used.

  In addition, extremely small electronic components are incorporated in small electronic devices such as mobile phones and digital cameras. Double-sided adhesive tape is used for fixing these electronic components, thin-layer nameplates, and fired sheets.

  The pressure-sensitive adhesive layer is desired to be a thin film so that the pressure-sensitive adhesive does not bleed after bonding. Small electronic devices that are becoming lighter, smaller, and thinner are required to have a thinner adhesive layer. From such a demand, a base material-less double-sided pressure-sensitive adhesive tape consisting only of a base material-less pressure-sensitive adhesive layer has been proposed.

  For example, Japanese Patent Application Laid-Open No. 7-41736 discloses a substrate-less double-sided pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing an acrylic copolymer as a main component.

However, the base material-less double-sided adhesive tape has the following problems.
(1) Since the double-sided pressure-sensitive adhesive tape without a substrate is likely to cause blocking, the tack cannot be increased.
(2) If there is no base material, the adhesive may not be sufficiently retained, and the adhesive is dragged out to the cutting blade when the base material-less double-sided adhesive tape is bonded to the adherend and die-cut. There is a problem. In addition, the adhesive layer may protrude during storage. When the pressure-sensitive adhesive protrudes in this way, blocking occurs when the pressure-sensitive adhesive tape is rewound, and it becomes unusable. This burr becomes a problem particularly when precision is required such as adhesion of electronic parts. That is, there is a problem that the bonded electronic component is lifted due to the presence of burrs, and the product is defective.

In order to solve these problems, Patent Document 2 provides a substrate-less double-sided pressure-sensitive adhesive tape having a three-layer pressure-sensitive adhesive layer. Of these three layers, the middle intermediate layer is a stretchable resin layer.
(In Patent Document 2, this resin layer is referred to as a substrate.) A first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer are provided on the front and back surfaces of the resin layer. Since this intermediate layer has good cutting properties, the problems such as the adhesive (2) being dragged out by the cutting blade were solved. However, as the pressure-sensitive adhesive layer progresses, the thickness of the first and second pressure-sensitive adhesive layers that affect the tack performance becomes extremely thin compared to the single-layer baseless double-sided pressure-sensitive adhesive tape, resulting in a decrease in tack performance. There was a problem to do. In order to maintain the tack performance, the lower limit of the total thickness of this three-layer type was only 30 μm. Actually, this three-layer base material-less double-sided adhesive tape is manufactured and sold by the applicant of Patent Document 2, and the minimum product with the total thickness of the adhesive layer is product number 200A-30. The total thickness of the pressure-sensitive adhesive layer of this product is 30 μm. Further, compared with the single layer type, the manufacturing process is complicated, the manufacturing time is long, the manufacturing loss is large, and the cost is significantly increased.

JP 7-41736 A JP-A-11-209710

  The present invention provides a substrate-less double-sided pressure-sensitive adhesive tape that does not cause a decrease in tack performance, does not drag the pressure-sensitive adhesive when die-cut, and does not increase the manufacturing cost even if the pressure-sensitive adhesive layer is made thinner. Is an issue.

  As a result of earnest research on the pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive tape, the present inventor is able to adhere even if the pressure-sensitive adhesive layer is made thin by blending an appropriate amount of scaly particles in the pressure-sensitive adhesive layer. It was found that the initial adhesive strength (tack performance) to the body did not decrease and there was no drag of the adhesive when die-cutting, and the present invention was completed.

That is, the present invention provides the following substrate-less double-sided pressure-sensitive adhesive tape.
(1) In a base-less double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on a release sheet, the pressure-sensitive adhesive layer has a thickness of 1 to 15 μm, and an average particle length and average width of 40 to 400 μm. A baseless double-sided pressure-sensitive adhesive tape comprising 0.5 to 5% by weight of scaly glass particles having a length ratio of 1: 1 to 3 .
(2) The substrate-less double-sided pressure-sensitive adhesive tape according to item (1), wherein the scale-like particles have a Mohs hardness of 4.5 or more.

  The base-less double-sided pressure-sensitive adhesive tape of the present invention does not cause a decrease in the tack performance on the adherend even if the pressure-sensitive adhesive layer is made thinner, and does not drag the pressure-sensitive adhesive when die-cutting.

  An organic polymer film support and a paper support are preferably used as the support for the release sheet in the substrate-less double-sided pressure-sensitive adhesive tape of the present invention. As the organic polymer film support, various film supports such as a polyester film, a polycarbonate film, a polymethyl methacrylate film, a polypropylene film, and a polyimide film can be used, but a polyester film is preferable from the viewpoint of cost and performance. Moreover, the thickness of a film support body has the preferable range of 20-100 micrometers from die cut property and a cost surface. In addition, as the paper support, high-density paper such as glassine paper, laminated paper in which a resin film such as polyethylene is laminated on clay-coated paper, kraft paper, or high-quality paper can be used. From the viewpoint of performance, glassine paper is preferred. The thickness of the paper support is preferably in the range of 20 to 100 μm.

  In addition, these support bodies turn into a release sheet in which both surfaces have peelability by apply | coating release agents, such as a silicone compound, a fluororesin, and a fluorosilicone resin, on the surface of both surfaces of a support body. The peeling force on both sides of the support needs to be differentiated into a surface having a light peeling force and a surface having a heavy peeling force. As a differentiation method, there is a method based on a difference in the thickness of the release agent or a difference in the type of the release agent.

  The pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer in the substrate-less double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited, and a general pressure-sensitive adhesive composition can be used. An agent is an essential component, and if necessary, a compound containing a tackifier resin can be suitably used.

  As the acrylic copolymer, one or more of (meth) acrylic acid alkyl ester having 4 to 18 carbon atoms in the alkyl group and another monomer having an ethylenically unsaturated bond that can be copolymerized are used. A copolymer with 1 type (s) or 2 or more types is mentioned.

  Examples of the (meth) acrylic acid alkyl ester include n-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, and isooctyl. (Meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned.

  Examples of the monomer having a copolymerizable ethylenically unsaturated bond include acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, cyclohexyl (meth) acrylate, Styrene, α-methylstyrene, vinyl acetate, N-vinyl-2-pyrrolidone, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, acrylic acid, methacrylic acid, itacon An acid, fumaric acid, etc. are mentioned. In the production of the acrylic copolymer, a monomer having a functional group capable of reacting with a crosslinking agent described later (for example, a monomer having a carboxyl group) is used as an essential component as a monomer having a copolymerizable ethylenically unsaturated bond. To do.

  As tackifying resins, rosin, rosin phenol resins, and rosin resins such as ester compounds and metal salts thereof, terpene polymers, terpene phenol resins, terpene resins such as aromatic modified terpene resins, styrene resins, Coumarone-indene resin, alkylphenol resin, xylene resin, C5 petroleum resin, C9 petroleum resin, alicyclic hydrogenated resin, etc. are mentioned. When used by blending with a polymer, natural resin-based rosin resins and terpene resins exhibiting good adhesion and initial tackiness to adherends such as paper and various films are preferably used.

  In the pressure-sensitive adhesive composition of the present invention, examples of the crosslinking agent used for crosslinking the acrylic copolymer include hexamethylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 2-chloro-1,4- Diisocyanate compounds such as phenyl diisocyanate, trimethylhexamethylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, biuret-type trimers of these diisocyanate compounds, isocyanurate-type trimers, isocyanate-based crosslinking agents such as triisocyanate, epoxy-based Examples thereof include a cross-linking agent, a melamine-based cross-linking agent, a metal chelate-based cross-linking agent, and an adduct of a polyol such as trimethylol propane, which can be appropriately selected and used.

  In the pressure-sensitive adhesive composition, scaly particles are added to improve the die-cutting property. The thickness of the scaly particles is preferably 1 to 15 μm. When the thickness is less than the above range, the die-cutting property is inferior, and when it exceeds the above range, the adhesive strength is lowered. In addition, the average length and average width of the scaly particles are preferably 40 to 400 μm in consideration of die cutting properties. When the average length and the average width are less than the above range, the die-cutting property is inferior. When the average length and the average width are above the above range, the heat-sensitive adhesive layer is not properly applied and cannot be uniformly applied. Further, considering the die-cutting property, the ratio of the average width to the average length of the scaly particles is preferably 1: 1 to 3. Here, the average length and the average width of the scaly particles means that both the average length and the average width of the scaly particles are in the range of 40 to 400 μm. The length and width of the scaly particles are the longest side of the flat surface of the particle, and the height in the direction perpendicular to the longest side is the width. Furthermore, the hardness of the particles is preferably a Mohs hardness of 4.5 or more in consideration of die cutability. When the Mohs hardness is less than 4.5, the die-cutting property is inferior.

As flaky particles, flaky glass particles, flaky mica, flaky synthetic mica, calcined mica,
Magicite, kanemite, montmorillonite, saponite, laponite, hectorite, barcumulite, kaolinite, halloysite, kanemite, macatite, iraite, agadiaite, kenyanite, sericite, calcined sericite, bentonite, zonotrite, smectite, vamorite, scaly graphite , Boron nitride, silica-X, silica-Y and the like. Examples of silica-X and silica-Y include flaky silica described in JP-A No. 2001-163613. In addition, there are particles obtained by processing metal powder into a scale shape, and examples of the material include gold, silver, aluminum, copper, brass, chromium, tin, lead, indium and the like.

As needed, what surface-treated the scaly particle | grains can be used. Examples of the surface treatment method include those obtained by hydrolyzing Si—O—Si bonds on the particle surface with a weak alkali, or those obtained by surface treatment with a coupling agent such as tetraethoxysilane.
Examples of the weak alkali include ammonia and triethanolamine, but are not limited thereto. A desirable reaction pH range is pH 13 to 9, particularly pH 11 to 9.

Among the scaly particles, scaly glass particles that can be processed freely in size, and have low cost and transparency are particularly preferable. Since the scale-like glass particles have a Mohs hardness of 4.5 or more, they are also excellent in die cutting properties. Generally, scaly glass particles are called glass flakes.

  The amount of the scaly particles is 0.5 to 5 wt% in the total amount of the pressure-sensitive adhesive layer (the total amount of the pressure-sensitive adhesive composition in terms of solid content) from the viewpoint of tackiness, die-cutting properties and particle dispersibility of the pressure-sensitive adhesive layer. % Is preferred.

  In the pressure-sensitive adhesive composition, an inorganic or organic colorant may be added within a range that does not impair adhesive strength, tackiness, die-cutting properties, etc., and the adhesive layer may be colored.

  The thickness of the pressure-sensitive adhesive layer is preferably in the range of 5 to 100 μm, more preferably in the range of 5 to 40 μm, in consideration of the adhesive force to the adherend, the holding power, and the die cutting property. In particular, when the film thickness is reduced, the range is 5 to 25 μm. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition using, for example, a bar coater, roll coater, gravure coater, knife coater, die coater, comma coater, lip coater or the like.

  The pressure-sensitive adhesive layer of the substrate-less double-sided pressure-sensitive adhesive tape of the present invention may be a two-layer type pressure-sensitive adhesive layer. For example, if the materials of the two adherends are different materials of acrylic resin and rubber, if an acrylic adhesive layer is used for the adhesive in a one-layer type adhesive layer, Adhesive strength is satisfactory, but for rubber, the adhesive strength is not satisfactory. In such a case, as the two-layered pressure-sensitive adhesive layer, an acrylic pressure-sensitive adhesive may be used for one pressure-sensitive adhesive layer, and a rubber-based pressure-sensitive adhesive may be used for the other pressure-sensitive adhesive layer. Adhesive strength is satisfied for any of the adherends when the acrylic pressure-sensitive adhesive layer is bonded to the acrylic resin of the adherend and the rubber-type pressure-sensitive adhesive layer is bonded to the rubber. It is preferable that each of the two layers contains scaly particles, but the effect of the present invention can be obtained even if contained in only one layer.

  Further, the present invention can be applied even if scale-like particles are contained in at least one of the first pressure-sensitive adhesive layer, the intermediate layer, and the second pressure-sensitive adhesive layer in the three-layer baseless double-sided pressure-sensitive adhesive tape described in Patent Document 2. The effect of can be obtained.

  In the above description, a single release sheet was used as a baseless double-sided pressure-sensitive adhesive tape, but two release sheets, a light release sheet and a heavy release sheet, were prepared, and each side of the pressure-sensitive adhesive layer of the present invention was prepared on each side. It is good also as a base-material-less double-sided adhesive tape on both sides of a peeling sheet.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. In the following, “parts” means parts by weight, and the coating amount, the number of parts, the mixing ratio, etc. are all expressed in terms of solid content.

Example 1
(Manufacture of release sheet)
On one side of a 50 μm thick polyester film, 93 parts of a silicone release agent (“KS-3601” manufactured by Shin-Etsu Chemical Co., Ltd.) and 5 parts of a crosslinking agent (“cat.PL-50T” manufactured by Shin-Etsu Chemical Co., Ltd.) And a mixture of 2 parts of silica powder (“Nippal E220A” manufactured by Nippon Silica Kogyo Co., Ltd.) are coated with a gravure coater so that the dry weight is 0.4 g / m ² and dried with hot air to form a heavy release layer. Then, on the other side of the polyester film, 95 parts of a silicone release agent (“KS-3650” manufactured by Shin-Etsu Chemical Co., Ltd.) and a crosslinking agent (“cat.PL-50T” manufactured by Shin-Etsu Chemical Co., Ltd.) 5 Part of the mixture was coated with a gravure coater so that the dry weight was 0.4 g / m ² and dried with hot air to form a light release layer to obtain a release sheet.

(Manufacture of adhesive composition)
First, 98 parts of an acrylic adhesive (“SK Dyne 801B” manufactured by Soken Chemical Co., Ltd., containing an acrylic copolymer and a tackifier resin) and a crosslinking agent (“Curing Agent L-” manufactured by Soken Chemical Co., Ltd.) 45 ") 2 parts were mixed to obtain a base acrylic pressure-sensitive adhesive composition. The final pressure-sensitive adhesive is obtained by mixing 5 parts of scaly glass particles (Mohs hardness: 6.5, thickness: 5 μm, average length: 150 μm, average width: 100 μm) with 95 parts of this base adhesive composition. An agent composition was obtained.
The thickness, length, and width of the scaly particles were determined by observing the particles with a metal microscope. The average length and average width were determined as average values for 50 particles arbitrarily selected (hereinafter the same).

(Manufacture of double-sided adhesive tape with no substrate)
The pressure-sensitive adhesive composition is applied onto the light release layer of the release sheet with a comma coater so as to have a thickness of 20 μm (when dried), dried at 100 ° C. for 3 minutes, and then bonded to the heavy release layer side. Then, it was wound up into a roll shape and further slitted into a width of 25 mm to obtain a substrate-less double-sided pressure-sensitive adhesive tape.

Example 2
0.5 parts of scaly glass particles (Mohs hardness: 6.5, thickness: 5 μm, average length: 150 μm, average width: 100 μm) are mixed with 99.5 parts of the base pressure-sensitive adhesive composition in Example 1. A substrate-less double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that.

Example 3
Except for mixing 3 parts of scaly glass particles (Mohs hardness: 6.5, thickness: 4 μm, average length: 300 μm, average width: 250 μm) to 97 parts of the base pressure-sensitive adhesive composition in Example 1, A substrate-less double-sided pressure-sensitive adhesive tape was obtained in the same manner as Example 1.

Reference example 4
Example 1 except that 3 parts of scaly mica (Mohs hardness: 3, thickness: 2 μm, average length: 50 μm, average width: 35 μm) were mixed with 97 parts of the base adhesive composition in Example 1. In the same manner, a baseless double-sided pressure-sensitive adhesive tape was obtained.

Reference Example 5
Except for mixing 5 parts of scaly glass particles (Mohs hardness: 6.5, thickness: 5 μm, average length: 15 μm, average width: 10 μm) to 95 parts of the base pressure-sensitive adhesive composition in Example 1, A substrate-less double-sided pressure-sensitive adhesive tape was obtained in the same manner as Example 1.

Comparative Example 1
A base-less double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that 97 parts of the base pressure-sensitive adhesive composition in Example 1 was mixed with 3 parts of granular fluororesin particles (average particle size: 3.5 μm). It was.

Comparative Example 2
A base-less double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that 97 parts of the base pressure-sensitive adhesive composition in Example 1 was mixed with 3 parts of granular polyethylene particles (average particle size: 20 μm).

Comparative Example 3
A baseless double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that 97 parts of the base pressure-sensitive adhesive composition in Example 1 was mixed with 3 parts of spherical silicone particles (average particle size: 12 μm).

Comparative Example 4
Except that 97 parts of the base pressure-sensitive adhesive composition in Example 1 were mixed with 3 parts of acicular glass particles (Mohs hardness: 6.5, diameter: 10 μm, average length: 70 μm), the same as in Example 1 Thus, a baseless double-sided adhesive tape was obtained.

Comparative Example 5
Example 1 except that the pressure-sensitive adhesive layer was constituted only by the base pressure-sensitive adhesive composition in Example 1.
In the same manner, a baseless double-sided pressure-sensitive adhesive tape was obtained.

(Measurement of physical properties)
Each substrate-less double-sided pressure-sensitive adhesive tape obtained above was cured for 7 days in a constant temperature and humidity chamber at 20 ° C. and 65% RH, and then the initial adhesive strength and die-cut property were measured. The results are shown in Table 1.

Each physical property was measured under the following conditions.
(1) Initial adhesive strength (tack force)
In accordance with JIS Z0237, a test piece was bonded to a SUS304 steel plate and 1 after 20 minutes.
The 80 ° peel strength was measured. The tensile speed was 300 mm / min. The value of the initial adhesive strength (gf / 25 mm) shown in Table 1 is an average value for 10 test pieces. The initial adhesive strength (gf / 25 mm) was determined according to the following criteria.
A: 1,000 gf / 25 mm or more; Extremely good B: 800 gf / 25 mm or more, less than 1,000 gf / 25 mm; Good Δ: 650 gf / 25 mm or more, less than 800 gf / 25 mm; Slightly inferior x: Less than 650 gf / 25 mm;

(2) Die-cutting property Die-cutting property: A sheet was cut so that the release sheet of the baseless double-sided adhesive tape was separated into two parts with a safety razor blade, and the threading state of the adhesive was observed when it was pulled horizontally from both sides.
Evaluation was performed based on the following criteria.
◎: The cut edge was cleanly separated. ○: Adhesive threading was found on a very small part of the cut. △: Adhesive threading was found on a part of the cut. X: Adhesive thread was present on a considerable part of the cut. XX: There was adhesive stringing across the entire cut surface

It is sectional drawing of the typical structural example of the base-material-free double-sided adhesive tape of this invention. It is sectional drawing of the other structural example of the base material less double-sided adhesive tape of this invention.

Explanation of symbols

1 Scaled Particle 2 Adhesive Layer 3 Heavy Release Layer 4 Support A
5 Light release layer 6 Support B

Claims (2)

In the base material-less double-sided pressure-sensitive adhesive tape used for die-cutting having a pressure-sensitive adhesive layer on a release sheet, the pressure-sensitive adhesive layer has a thickness of 1 to 15 μm, an average particle length and average width of 40 to 400 μm, and an average width. A baseless double-sided pressure-sensitive adhesive tape for use in die-cutting, which contains 0.5 to 5% by weight of glass flake particles having an average length ratio of 1: 1 to 3 . The substrate-less double-sided pressure-sensitive adhesive tape used for die-cutting according to claim 1, wherein the scale-like glass particles have a Mohs hardness of 4.5 or more.

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