JP2018048266A - Double-sided adhesive tape or sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided adhesive tape or sheet which is excellent in strength, adhesiveness and insulating properties even when having a small thickness and is also excellent in electrolyte resistance.SOLUTION: The double-sided adhesive tape or sheet of the present invention includes a laminate comprising a support and two adhesive layers formed on both surfaces of the support. The support contains a polypropylene resin. The adhesive layers contain a polyolefin-based adhesive. The total thickness (Ds) of the laminate is 2.5-12 μm. The ratio Dp/Ds of the thickness (Dp) of the support to the total thickness (Ds) of the laminate is 0.3-0.8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape or sheet and a method for producing the same.

  Double-sided pressure-sensitive adhesive tapes or double-sided pressure-sensitive adhesive sheets (referred to herein as “double-sided pressure-sensitive adhesive tapes or sheets”) are used, for example, for assembling various electronic devices such as secondary ion batteries and mobile phones. Widely used as a material for fixing. In secondary batteries such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, lithium ion batteries, etc., for example, for the purpose of exerting functions such as core stopper, electrode outlet insulation, terminal stopper, or insulating spacer, An adhesive tape or sheet is used.

  In recent years, functions of various electronic devices have been diversified, as typified by secondary batteries for electronic devices such as mobile devices in particular, and demands for further miniaturization (thinning) and durability improvement have increased rapidly. Yes. Therefore, it is desired that the double-sided pressure-sensitive adhesive tape or sheet be extremely thin and further functionally improved. From this viewpoint, various double-sided pressure-sensitive adhesive tapes have been proposed. For example, a double-sided pressure-sensitive adhesive tape or sheet having a laminated structure in which pressure-sensitive adhesive layers are formed on both surfaces of a PET resin support (Patent Document 1, etc.) Or a double-sided pressure-sensitive adhesive tape or sheet (see Patent Documents 2, 3, etc.) that can be suitably applied to a secondary battery or the like.

JP 2005-105212 A Japanese Patent No. 3473929 JP 2006-40812 A

  However, when the double-sided pressure-sensitive adhesive tape or sheet is thinned, there is a problem that the performance such as strength, adhesiveness and insulation (dielectric breakdown characteristics) tends to be lowered. In addition, since the conventional double-sided pressure-sensitive adhesive tape or sheet has not been improved at all in terms of electrolyte resistance and dielectric breakdown voltage, it has a problem in terms of durability. In particular, since the secondary battery contains an electrolyte and the like, it is considered that this effect tends to cause deterioration and damage to the double-sided pressure-sensitive adhesive tape or sheet. The present inventor has found that there is room for improvement in the conventional double-sided pressure-sensitive adhesive tape or sheet from such a viewpoint.

  The present invention has been made in view of the above, and an object of the present invention is to provide a double-sided pressure-sensitive adhesive tape or sheet that is excellent in strength, adhesiveness, and insulation properties even in a thin thickness, and that is also excellent in electrolyte resistance. To do.

  As a result of intensive studies to achieve the above object, the present inventor achieved the above object by adjusting the thickness of the polypropylene resin support and the total thickness of the support and the pressure-sensitive adhesive layer to an appropriate range. The present inventors have found that this can be done and have completed the present invention.

  That is, the present invention includes, for example, the inventions described in the following sections.

Item 1. A double-sided pressure-sensitive adhesive tape or sheet comprising a support and a laminate composed of two pressure-sensitive adhesive layers formed on both sides of the support,
The support includes a polypropylene resin,
The pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive,
The total thickness (Ds) of the laminate is 2.5 to 12 μm,
The double-sided pressure-sensitive adhesive tape or sheet, wherein the value of the ratio Dp / Ds between the thickness (Dp) of the support and the total thickness (Ds) of the laminate is 0.3 to 0.8.
Item 2. Item 2. The double-sided pressure-sensitive adhesive tape or sheet according to item 1, wherein the support has a thickness (Dp) of 1.5 to 6 μm.
Item 3. Item 3. The double-sided pressure-sensitive adhesive tape or sheet according to Item 1 or 2, wherein both the breaking strength in the flow direction and the breaking strength in the width direction of the laminate are 50 to 260 MPa.
Item 4. The double-sided pressure-sensitive adhesive tape or sheet according to any one of items 1 to 3, wherein the dielectric breakdown voltage of the laminate is 1 to 8 kV.
Item 5. Item 5. The double-sided pressure-sensitive adhesive tape or sheet according to any one of Items 1 to 4, wherein the support is a biaxially stretched polypropylene film.
Item 6. Item 6. The double-sided pressure-sensitive adhesive tape or sheet according to any one of Items 1 to 5, wherein the polypropylene resin has a melting point of 155 to 180 ° C.
Item 7. The said support body contains 80-100 mass% of isotactic homopolypropylenes whose meso pentad fraction is 90-99.5% with respect to the total mass of this support body, The any one of claim | item 1 -6. Double-sided pressure-sensitive adhesive tape or sheet as described in 1.
Item 8. Item 8. The double-sided pressure-sensitive adhesive tape or sheet according to Item 7, wherein the isotactic homopolypropylene has a melt mass flow rate (MFR) of 1.5 to 6 g / 10 min.
Item 9. The double-sided pressure-sensitive adhesive tape or sheet according to any one of Items 1 to 8, and a separator,
The separator is a laminated tape or sheet formed outside the pressure-sensitive adhesive layer on at least one side of the double-sided pressure-sensitive adhesive tape or sheet.
Item 10. Item 10. The laminated tape or sheet according to Item 9, wherein the separator is formed on the outer sides of the pressure-sensitive adhesive layers on both sides.
Item 11. A method for producing a double-sided pressure-sensitive adhesive tape or sheet comprising a laminate comprising a support and two pressure-sensitive adhesive layers formed on both sides of the support,
Forming the support with a raw material comprising a polypropylene resin, and
A step of forming the pressure-sensitive adhesive layer with a pressure-sensitive adhesive layer-forming composition containing a polyolefin-based pressure-sensitive adhesive,
The total thickness (Ds) of the laminate is 2.5 to 12 μm,
The manufacturing method whose value of ratio Dp / Ds of the thickness (Dp) of the said support body and the total thickness (Ds) of the said laminated body is 0.3-0.8.
Item 12. Forming the pressure-sensitive adhesive layer on the separator;
A step of producing a laminated tape or sheet by laminating the surface on which the pressure-sensitive adhesive layer of the separator is formed on one side or both sides of the support; and
Peeling the separator from the laminated tape or sheet;
Item 12. The manufacturing method according to Item 11, comprising:
Item 13. Item 13. The manufacturing method according to Item 11 or 12, wherein the polypropylene resin has a melting point of 155 to 180 ° C.
Item 14. The raw material containing the polypropylene resin contains 80 to 100% by mass of isotactic homopolypropylene having a mesopentad fraction of 90 to 99.5% with respect to the total mass of the raw material. 2. The production method according to item 1.
Item 15. The manufacturing method of any one of Claims 11-14 whose melt mass flow rate (MFR) of the said isotactic homopolypropylene is 1.5-6 g / 10min.
Item 16. Forming a pressure-sensitive adhesive layer on the separator; and
Bonding the surface on the side where the pressure-sensitive adhesive layer of the separator is formed on one side or both sides of the support,
A method for producing a laminated tape or sheet.

  The double-sided pressure-sensitive adhesive tape or sheet according to the present invention is excellent in strength, adhesiveness and insulation even at a thin thickness, and is also excellent in electrolyte resistance. Moreover, since the double-sided pressure-sensitive adhesive tape or sheet according to the present invention can be extremely thinned, it can be suitably used for, for example, a secondary battery.

It is sectional drawing which shows an example of embodiment of the double-sided adhesive tape or sheet | seat of this invention. It is sectional drawing which shows an example of embodiment of the lamination | stacking tape or sheet | seat of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, the expressions “containing” and “including” include the concepts of “containing”, “including”, “consisting essentially of”, and “consisting only of”.

1. The double-sided pressure-sensitive adhesive tape or sheet The present invention is a double-sided pressure-sensitive adhesive tape or sheet comprising a support and a laminate composed of two pressure-sensitive adhesive layers formed on both sides of the support,
The support includes a polypropylene resin,
The pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive,
The total thickness (Ds) of the laminate is 2.5 to 12 μm,
The ratio Dp / Ds between the thickness (Dp) of the support and the total thickness (Ds) of the laminate is 0.3 to 0.8.

  In the present specification, the double-sided pressure-sensitive adhesive tape or sheet means a double-sided pressure-sensitive adhesive tape or double-sided pressure-sensitive adhesive sheet.

  The double-sided pressure-sensitive adhesive tape or sheet is excellent in strength, adhesiveness, and insulation even in a thin thickness, and is also excellent in electrolyte resistance.

  FIG. 1 is an example of an embodiment of the double-sided tape or sheet of the present invention, and represents a cross-sectional view of the double-sided pressure-sensitive adhesive tape or sheet.

  A double-sided pressure-sensitive adhesive tape or sheet 1 in the form of FIG. 1 is formed by a laminate 10 composed of a support 11 and two pressure-sensitive adhesive layers 12 formed on both sides of the support 11. In FIG. 1, the two adhesive layers 12 are a first adhesive layer 12a and a second adhesive layer 12b, respectively. In FIG. 1, Ds represents the total thickness of the laminate 10, and Dp represents the thickness of the support 11.

  Hereinafter, the structure of the double-sided pressure-sensitive adhesive tape or sheet of the present invention will be described in detail.

(Support)
The support is a constituent member for supporting the pressure-sensitive adhesive layer, and is formed in a long tape shape or a sheet shape.

  The support includes a polypropylene resin.

  The type of the polypropylene resin is not particularly limited. Examples of the polypropylene resin include propylene homopolymers such as isotactic polypropylene and syndiotactic polypropylene; copolymers of propylene and ethylene; long-chain branched polypropylene; ultrahigh molecular weight polypropylene.

  One type of polypropylene resin contained in the support may be used alone, or two or more types may be used.

  The main component of the support is preferably a polypropylene resin. The “main component” means 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and still more preferably 99% in terms of solid content in the support. It means containing more than mass%.

  The support may be composed of only a polypropylene resin, or may contain a material other than the polypropylene resin as long as the effects of the present invention are not impaired. For example, the support may contain additives such as an antioxidant, a chlorine absorbent, an ultraviolet absorbent, a lubricant, a plasticizer, a flame retardant, and a colorant in addition to various resins other than the polypropylene resin. Examples of resins other than polypropylene resins include olefin resins other than polypropylene, polyamide resins, polyimide resins, methacrylate resins, styrene resins, and polycarbonate resins (PC). These may be contained alone in the support, or may be contained in combination of two or more.

  The support preferably contains 80 to 100% by mass of isotactic homopolypropylene having a mesopentad fraction of 90 to 99.5% based on the total mass of the support. In this case, since the strength of the double-sided pressure-sensitive adhesive tape or sheet is improved and the dielectric breakdown voltage is also improved, the insulation and durability are more excellent. In particular, when isotactic homopolypropylene having a mesopentad fraction of 91 to 99.5% (more preferably 92 to 99%, more preferably 93.5 to 98.5%) is contained in an amount of 80 to 100% by mass. In addition, the dielectric breakdown voltage is further improved.

The mesopentad fraction ([mmmm]) is an index of stereoregularity that can be obtained by high temperature nuclear magnetic resonance (NMR) measurement. Specifically, it can measure using the JEOL Co., Ltd. make, high temperature type Fourier-transform nuclear magnetic resonance apparatus (high temperature FT-NMR), and JNM-ECP500, for example. The observation nucleus is ¹³ C (125 MHz), the measurement temperature is 135 ° C., and a solvent for dissolving the polypropylene resin is ortho-dichlorobenzene (ODCB: ODCB and deuterated ODCB mixed solvent (mixing ratio = 4/1). The measurement method by high temperature NMR is, for example, the method described in “Japan Analytical Chemistry / Polymer Analysis Research Roundtable, New Edition Polymer Analysis Handbook, Kinokuniya, 1995, p. 610”. Can be done with reference to.

The measurement mode is single pulse proton broadband decoupling, the pulse width is 9.1 μsec (45 ° pulse), the pulse interval is 5.5 sec, the number of integration is 4500 times, and the shift reference is CH ₃ (mmmm) = 21.7 ppm. be able to.

  The pentad fraction representing the degree of stereoregularity is a combination of the quintet (pentad) of the consensus “meso (m)” arranged in the same direction and the consensus “rasemo (r)” arranged in the opposite direction (mmmm and mrrm). Etc.) based on the integrated value of the intensity of each signal derived from. Each signal derived from mmmm, mrrm and the like can be assigned with reference to, for example, “T. Hayashi et al., Polymer, 29, 138 (1988)”.

  When the support contains isotactic homopolypropylene having the mesopentad fraction of 90 to 99.5%, the melt mass flow rate (MFR) of the isotactic homopolypropylene is 1.5 to 6 g / 10 min. It is preferably 2 to 5 g / 10 min, more preferably 2 to 4 g / 10 min. In this case, since the stretchability of the film or sheet formed of isotactic homopolypropylene is excellent, it becomes easy to adjust the thickness of the double-sided pressure-sensitive adhesive tape or sheet.

  The melt flow rate (MFR) here is a measured value at 230 ° C. and a load of 21.18 N, and can be measured in accordance with JIS K 7210-1999.

  The weight average molecular weight (Mw) of the polypropylene resin is not particularly limited, but is preferably 250,000 to 500,000. If the support contains such a polypropylene resin having a weight average molecular weight (Mw), an appropriate resin fluidity can be obtained during biaxial stretching, the thickness of the support can be easily controlled, and unevenness in thickness occurs. It becomes difficult.

  The molecular weight distribution (Mw / Mn) calculated as a ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polypropylene resin is not particularly limited, but is preferably 4 or more and 12 or less. When the support contains a polypropylene resin having such a molecular weight distribution (Mw / Mn), an appropriate resin fluidity can be obtained during biaxial stretching, the thickness of the support can be easily controlled, and unevenness in thickness occurs. It becomes difficult to do.

  The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polypropylene resin can be measured by a gel permeation chromatography (GPC) method. The GPC apparatus used for the GPC method is not particularly limited, and is a commercially available high-temperature GPC measuring machine capable of analyzing the molecular weight of polyolefin resin, for example, a high-temperature GPC measuring machine with a built-in differential refractometer (RI) manufactured by Tosoh Corporation. HLC-8121GPC-HT or the like can be used. In this case, for example, a GPC column manufactured by Tosoh Co., Ltd., with three TSKgel GMHHR-H (20) HT connected is used, the column temperature is set to 145 ° C., and trichlorobenzene is used as the eluent. Measured at a flow rate of 1.0 ml / min. Usually, a calibration curve is prepared using standard polystyrene, and the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be obtained by polystyrene conversion.

  The melting point of the polypropylene resin is preferably 155 to 180 ° C. In this case, since the melting point of the support itself containing the polypropylene resin is increased, the dielectric breakdown voltage of the double-sided pressure-sensitive adhesive tape or sheet is also particularly improved. The melting point is more preferably 155 to 170 ° C.

  In this invention and this specification, it is prescribed | regulated by the measurement by a differential scanning calorimeter (DSC) method that melting | fusing point of polypropylene resin is 155-180 degreeC. Specifically, in the DSC measurement of polypropylene resin, the temperature is increased from 30 ° C. to 280 ° C. at a rate of 20 ° C./min and held at 280 ° C. for 5 minutes under a nitrogen flow, and then at 20 ° C./min to 30 ° C. The DSC curve obtained when cooled and held at 30 ° C. for 5 minutes and then heated up to 280 ° C. at 20 ° C./min has at least one melting peak, and the melting peak (multiple melting peaks) When the maximum melting peak is in the range of 155 to 180 ° C, the melting point of the polypropylene resin can be defined as 155 to 180 ° C.

  A polypropylene resin can be manufactured using a conventionally well-known method. Examples of the polymerization method include a gas phase polymerization method, a bulk polymerization method, and a slurry polymerization method. The polymerization may be one-stage polymerization using one polymerization reactor, or may be multistage polymerization using two or more polymerization reactors. Moreover, you may superpose | polymerize by adding hydrogen or a comonomer as a molecular weight regulator in a reactor. A conventionally known Ziegler-Natta catalyst can be used as the polymerization catalyst, and the polymerization catalyst may contain a promoter component and a donor. The molecular weight, molecular weight distribution, stereoregularity and the like of the polypropylene resin can be controlled by appropriately adjusting the polymerization catalyst and other polymerization conditions.

  The support can be formed using, for example, a raw material containing a polypropylene resin (hereinafter, the raw material is also referred to as a polypropylene resin composition). Hereinafter, the step of forming a support using the polypropylene resin composition may be referred to as “support formation step”. In this support body formation process, for example, after a polypropylene resin composition is extruded into a sheet shape, the support body can be formed by biaxial stretching.

  In the support forming step, the polypropylene resin contained in the polypropylene resin composition may be in the form of pellets or powder. Alternatively, the polypropylene resin contained in the polypropylene resin composition may be a mixture of pellets and powder.

  The method of extrusion molding is not particularly limited. For example, as a method of extrusion molding, the above polypropylene resin composition is supplied to an extruder, heated and melted, passed through a filtration filter as necessary, heated and melted at a predetermined temperature, and melt extrusion from a T die is performed. Thereafter, there is a method of cooling and solidifying with at least one metal drum. Thereby, an unstretched cast original fabric sheet is obtained. The heating and melting temperature can be, for example, about 170 ° C. to 320 ° C., preferably about 200 ° C. to 270 ° C. The metal drum can be maintained, for example, usually at about 20 ° C to 140 ° C, preferably about 30 ° C to 120 ° C, more preferably about 40 ° C to 100 ° C. The thickness of the unstretched cast raw sheet can be about 0.05 mm to 2 mm, more preferably about 0.07 mm to 1 mm, and further preferably about 0.1 to 0.6 mm. .

  Thus, a support body can be obtained by biaxially stretching the cast raw sheet obtained in the support body forming step, for example. Examples of the stretching method include simultaneous or sequential biaxial stretching methods. From the viewpoint of easily improving the dielectric breakdown voltage, the sequential biaxial stretching method is preferable.

  The sequential biaxial stretching method can be performed as follows, for example. First, the raw sheet is preferably maintained at a temperature of 100 to 180 ° C., more preferably 120 to 170 ° C., and it is passed through a roll having a difference in peripheral speed or by the tenter method, preferably 2 to 2 in the longitudinal direction. The film is stretched 10 times, more preferably 2.5 to 8 times, still more preferably 3 to 6 times. Subsequently, the stretched film is subjected to a tenter method, preferably at a temperature of 100 to 180 ° C., more preferably 120 to 175 ° C., preferably 2 to 12 times, more preferably 2.5 to 11.5 times in the transverse direction. More preferably, the film may be stretched 3 to 11 times, relaxed in the lateral direction by about 5 to 10%, and subjected to thermal relaxation and wound up.

  The support is preferably a biaxially stretched polypropylene film. In this case, since the strength of the support is further increased, the strength of the double-sided pressure-sensitive adhesive tape or sheet itself is improved, and the desired strength is easily maintained even if the thickness is reduced.

  The thickness Dp of the support is preferably 1.5 to 6 μm. Within this range, it is easy to adjust the total thickness Ds and Dp / Ds of the laminate to a predetermined range, and the double-sided pressure-sensitive adhesive tape or sheet is excellent in strength, adhesiveness and insulation, and more resistant to electrolytes. Rise. The thickness Dp of the support is more preferably 1.8 to 5 μm, and particularly preferably 2 to 4 μm.

  The thickness Dp of the support can be adjusted by, for example, the manufacturing conditions in the support forming process. For example, the thickness Dp of the support can be adjusted by adjusting the draw ratio when the cast raw sheet is biaxially stretched. Further, the thickness of the cast original fabric sheet can be adjusted by, for example, the melting temperature, the extrusion speed, the cooling temperature, and the like at the time of extrusion molding.

  The support may have any form of a single layer structure and a laminated structure, and the structure is not restricted. When the support has a laminated structure, the composition of each layer may be the same, or a part or all of the layers may have different compositions.

  One side or both sides of the support may be subjected to, for example, oxidation treatment by a chemical or physical method such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric exposure, ionizing radiation treatment, or the like. In this case, the adhesion between the support and the pressure-sensitive adhesive layer is enhanced.

(Adhesive layer)
An adhesive layer is a layer which exhibits the adhesive performance as a double-sided adhesive tape or sheet.

  The pressure-sensitive adhesive layer is disposed so as to be in contact with the back surface or the main surface of the front surface of the support. Here, in this invention and this specification, the adhesive layer arrange | positioned so that it may contact | connect with the back surface of a support body is also called a 1st adhesive layer, and it is in contact with the front surface of a support body. The pressure-sensitive adhesive layer arranged in the above is also referred to as a second pressure-sensitive adhesive layer. As described above, each pressure-sensitive adhesive layer is represented as a first pressure-sensitive adhesive layer 12a and a second pressure-sensitive adhesive layer 12b in FIG.

  The pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive. More specifically, the pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive as a main component. The “main component” as used herein means 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and still more preferably in terms of solid content in the pressure-sensitive adhesive layer. Means 99% by mass or more.

  The pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive, thereby improving the adhesion between the polyolefin-based pressure-sensitive adhesive and the support, and delamination (that is, the phenomenon of peeling at the interface between the polyolefin-based pressure-sensitive adhesive and the support). It is hard to cause problems such as. The reason (mechanism) is that the polypropylene resin in the support and the polyolefin pressure-sensitive adhesive in the pressure-sensitive adhesive layer are common or similar in terms of chemical structure. This is presumably because the support and the pressure-sensitive adhesive layer are in close contact with each other. However, the reason (mechanism) that the double-sided pressure-sensitive adhesive tape or sheet of the present invention is excellent in the above-described effect will be clearly described here as being within the scope of the present invention even if it is different from the above-described reason (mechanism).

  The type of polyolefin pressure-sensitive adhesive is not particularly limited, and examples thereof include acid-modified polyolefin. In this case, the double-sided pressure-sensitive adhesive tape or sheet can have excellent adhesive force.

  The acid-modified polyolefin can be obtained, for example, by graft polymerization of an unsaturated carboxylic acid and / or an acid anhydride thereof to the polyolefin. Specifically, the acid-modified polyolefin includes, for example, a polyolefin (that is, a polyolefin before being acid-modified), an unsaturated carboxylic acid and / or an acid anhydride thereof in the presence of a radical generator such as a peroxide. It can be prepared by a melt kneading method or the like.

  Examples of the polyolefin before acid modification include ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1 A homopolymer of an α-olefin having 2 to 10 carbon atoms such as decene; a random or block polymer of two or more kinds of the α-olefin; a random, block or graft polymer of the α-olefin and another monomer Or mixtures thereof. Among these, polyolefins include ethylene resins such as high-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer (EVA), and propylene-based resins such as polypropylene because they are excellent in low cost and low-temperature adhesiveness. At least one selected is preferred.

  The acid-modified polyolefin may have, for example, a graft structure in which an unsaturated carboxylic acid and / or an acid anhydride thereof is bonded to a polyolefin skeleton serving as a main chain to form a side chain. In this case, any carbon atom adjacent to the carbonyl group in the unsaturated carboxylic acid and / or its anhydride can be attached to the polyolefin backbone.

  The graft ratio of the acid-modified polyolefin is, for example, about 0.05 to 10% by weight, preferably about 0.1 to 5% by weight with respect to the polyolefin to be grafted. In this case, adhesive strength is ensured, and acid-modified polyolefin is less likely to agglomerate, so that production efficiency is unlikely to deteriorate.

  The acid-modified polyolefin is preferably at least one selected from the group of maleic acid-modified polyolefin and maleic anhydride-modified polyolefin. In this case, the double-sided pressure-sensitive adhesive tape or sheet may have a particularly excellent adhesive force.

  The polyolefin pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer may be one kind alone, or two or more kinds.

  The pressure-sensitive adhesive layer can contain a petroleum resin for the purpose of adjusting the adhesive strength. Petroleum resin is produced by polymerizing a part of naphtha cracking by-product oil used in the petrochemical industry (C5 (meaning 5 carbon atoms) fraction or C9 (meaning 9 carbon atoms) fraction). C5 petroleum resin obtained by cationic polymerization of a C5 chain olefin mixture, dicyclopentadiene petroleum resin obtained by thermal polymerization of a dicyclopentadiene fraction, and C9 petroleum resin obtained by cationic polymerization of a C9 aromatic olefin mixture. , C5C9 copolymer petroleum resins, and resins obtained by hydrogenating them.

  The pressure-sensitive adhesive layer can contain a pressure-sensitive adhesive component other than the polyolefin-based pressure-sensitive adhesive. Examples of adhesive components other than polyolefin adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, styrene-diene block copolymer adhesives, and vinyl alkyls. Examples include ether-based adhesives, polyamide-based adhesives, fluorine-based adhesives, creep property improving adhesives, and radiation curable adhesives.

  The pressure-sensitive adhesive layer can also contain other components, for example, additives such as a crosslinking agent, a tackifier, a plasticizer, a filler, and an antioxidant.

  The two pressure-sensitive adhesive layers formed on both surfaces of the support may have the same component composition or different component compositions.

  An adhesive layer can be formed using the composition for adhesive layer formation containing a polyolefin-type adhesive, for example. Hereinafter, the step of forming the pressure-sensitive adhesive layer with the pressure-sensitive adhesive layer-forming composition containing the polyolefin-based pressure-sensitive adhesive may be referred to as “pressure-sensitive adhesive layer forming step”.

  The pressure-sensitive adhesive layer can be formed by a known method. For example, a method in which an adhesive layer is laminated on a support and melt-extruded and then stretched with the support, a method of melt-extrusion (laminate) on an unstretched support and then stretching with the support, on an unstretched support On a stretched support, a method of melt extrusion (laminate) on a stretched support, a method of coating on a stretched support, on another substrate (for example, a separator described later), etc. A method of adhering an adhesive layer formed by melt extrusion or coating to a support can be applied. Among these, from the viewpoint of easily controlling the thickness of the ultrathin pressure-sensitive adhesive layer as in the present invention, it is preferably formed by coating on a support or another substrate.

  When forming an adhesive layer by coating, an adhesive layer-forming composition can be used. The composition for forming an adhesive layer includes, for example, a polyolefin-based adhesive and a solvent for dissolving and / or dispersing the polyolefin-based adhesive. The type of polyolefin pressure-sensitive adhesive is as described above.

  The solvent contained in the composition for forming an adhesive layer is not particularly limited as long as it can dissolve the polyolefin-based adhesive, but for example, aromatic hydrocarbons such as toluene and xylene, n-heptane, methylcyclohexane, and the like. Organic solvents such as aliphatic hydrocarbons can be mentioned. The boiling point of the solvent is preferably 10 to 150 ° C, more preferably 20 to 120 ° C, from the viewpoint of easy handling of the coating liquid and easy production of the pressure-sensitive adhesive layer. The solvent may be a mixed solvent containing two or more kinds. The pressure-sensitive adhesive layer-forming composition may contain other additives, for example, pressure-sensitive adhesive components and additives other than the above-described polyolefin-based pressure-sensitive adhesives as necessary.

  The solid content concentration in the pressure-sensitive adhesive layer forming composition is preferably 1 to 20% by mass based on the total amount of the coating liquid, from the viewpoint of the stability of the coating liquid and the coating suitability. % Is more preferable, and 5 to 10% by mass is further preferable.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as the total thickness Ds and the Dp / Ds values satisfy a specific range. For example, the thickness of the pressure-sensitive adhesive layer can be set to 0.5 to 4 μm. Within this range, it is easy to adjust the values of the total thickness Ds and the Dp / Ds to predetermined ranges, and the adhesive strength can be high. The thickness of an adhesive layer here shows the thickness per one of the two adhesive layers currently formed in both surfaces of a support body. As for the thickness of an adhesive layer, it is more preferable that it is 0.7-3 micrometers, and it is especially preferable that it is 0.9-2.4 micrometers.

The thickness of the pressure-sensitive adhesive layer can be adjusted, for example, by adjusting the coating amount (g / m ² ) of the pressure-sensitive adhesive layer forming composition.

  The two pressure-sensitive adhesive layers formed on both sides of the support may be the same thickness or different thicknesses.

  The pressure-sensitive adhesive layer is preferably formed on the entire surface of each side of the support from the viewpoint of ensuring high adhesive strength of the double-sided pressure-sensitive adhesive tape or sheet.

  The pressure-sensitive adhesive layer may have any form of a single layer structure and a laminated structure, and the structure is not restricted. When the pressure-sensitive adhesive layer has a laminated structure, the composition of each layer may be the same, or a part or all of the layers may have different compositions.

(Laminate)
The laminate is formed of a support and two pressure-sensitive adhesive layers (a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer) formed on both sides of the support.

  In the present invention, the total thickness Ds of the laminate is 2.5 to 12 μm, and the value of Dp / Ds, which is the ratio of the thickness Dp of the support and the total thickness Ds of the laminate, is 0.3 to 0.8. The total thickness Ds of the laminate is the sum of the thickness of the support and the thickness of the two pressure-sensitive adhesive layers (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer). When the values of the total thickness Ds and Dp / Ds satisfy the above ranges, the double-sided pressure-sensitive adhesive tape or sheet is excellent in strength, adhesiveness, and insulating properties, and is also excellent in electrolyte resistance. That is, the double-sided pressure-sensitive adhesive tape or sheet is excellent in various physical properties despite being thin.

  Further, when the values of the total thickness Ds and Dp / Ds satisfy the above ranges, the double-sided pressure-sensitive adhesive tape or sheet is less likely to cause wrinkles or the like when bonded, and the bonding operation can be easily performed.

  Thus, in the double-sided pressure-sensitive adhesive tape or sheet having a support containing polypropylene resin, the ratio of the thickness Dp of the support to the total thickness Ds of the laminate is adjusted to an appropriate range in addition to the thickness Dp of the support. Therefore, various physical properties such as strength, adhesiveness, and electrolyte resistance are not easily lost, and the durability is excellent.

  When the total thickness Ds of the laminate is less than 2.5 μm, not only the strength of the double-sided pressure-sensitive adhesive tape or sheet is lowered, but also bonding becomes difficult. On the other hand, when the total thickness Ds of the laminate exceeds 12 μm, the double-sided adhesive tape or sheet becomes too thick, and it is difficult to apply to a small and thin secondary battery, and the range of use is limited.

  The lower limit of the total thickness Ds is preferably 3.0 μm, more preferably 3.3 μm, and particularly preferably 3.5 μm. The upper limit of the total thickness Ds is preferably 11.5 μm, more preferably 10 μm, and particularly preferably 8 μm.

  When the value of Dp / Ds is less than 0.3, the breaking strength of the laminate is lowered, and the double-sided pressure-sensitive adhesive tape or sheet is easily broken or damaged. On the other hand, if the value of Dp / Ds exceeds 0.8, the ratio of the support to the total thickness of the laminate becomes too high, causing a decrease in adhesiveness (particularly initial adhesiveness).

  The lower limit of the value of Dp / Ds is preferably 0.34, more preferably 0.36, and particularly preferably 0.38. Further, the upper limit of the value of Dp / Ds is preferably 0.75, more preferably 0.70, and particularly preferably 0.65.

  Both the breaking strength in the flow direction and the breaking strength in the width direction of the laminate are preferably 50 to 260 MPa. In this case, the strength of the double-sided pressure-sensitive adhesive tape or sheet is further increased. In particular, from the viewpoint of increasing the strength, the breaking strength in the flow direction of the laminate is more preferably 65 to 220 MPa, and particularly preferably 70 to 200 MPa. From the same viewpoint, the breaking strength in the width direction of the laminate is more preferably 70 to 220 MPa, and particularly preferably 90 to 200 MPa.

  The flow direction of a laminated body here corresponds to the longitudinal direction of a laminated body, and the width direction of a laminated body is equivalent to the transversal direction of a laminated body. For example, when the support body which comprises a laminated body is obtained by extrusion molding, the extrusion direction corresponds with a flow direction.

  The dielectric breakdown voltage of the laminate is preferably 1 to 8 kV. In this case, even when the double-sided pressure-sensitive adhesive tape or sheet is applied to, for example, a secondary battery, the deterioration of the double-sided pressure-sensitive adhesive tape or sheet is suppressed over a long period of time, and the durability is excellent. In particular, from the viewpoint of enhancing durability, the dielectric breakdown voltage of the laminate is more preferably 1.2 kV or more, and particularly preferably 1.5 kV or more. The upper limit of the dielectric breakdown voltage is usually 8 kV or less, but may be 6 kV or less.

  The double-sided pressure-sensitive adhesive tape or sheet of the present invention is formed of only a laminate comprising a support and two pressure-sensitive adhesive layers (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer) formed on both sides of the support. It may be. Or if it is a grade which does not inhibit the effect of this invention, the double-sided adhesive tape or sheet | seat of this invention contains a laminated body and may have another layer further. Examples of the other layer include a release treatment layer. The release treatment layer is, for example, a layer for allowing the double-sided pressure-sensitive adhesive tape or sheet to be easily peeled even after being attached to an adherend such as metal, plastic, or film. The release treatment layer can be formed, for example, on the outer surface of one or both pressure-sensitive adhesive layers of the laminate. The material for forming the release treatment layer is not particularly limited. For example, the release treatment layer can be formed from a release treatment agent such as a silicone release treatment agent, a fluorine release treatment agent, or a long-chain alkyl release treatment agent.

2. Laminated tape or sheet By using the double-sided pressure-sensitive adhesive tape or sheet of the present invention, a laminated tape or sheet can be formed.

  For example, a laminated tape or sheet can be formed including the double-sided pressure-sensitive adhesive tape or sheet of the present invention and a separator. In this laminated tape or sheet, the separator may be formed outside the pressure-sensitive adhesive layer on at least one side of the double-sided pressure-sensitive adhesive tape or sheet. Or the said separator may be formed in each outer side of the said adhesive layer of the both sides of a double-sided adhesive tape or a sheet | seat. In addition, the outer side of an adhesive layer means the surface on the opposite side to a support body of an adhesive layer.

  A separator here is a member for protecting an adhesive layer and preventing blocking.

  FIG. 2 shows an example of a laminated tape or sheet, and shows a cross-sectional view of the laminated tape or sheet. The laminated tape or sheet 2 in the form of FIG. 2 has a double-sided pressure-sensitive adhesive tape or sheet 1 and a pair of separators 13. Each of the pair of separators 13 is disposed so as to face the outside of each of the pressure-sensitive adhesive layers 12 (that is, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) on both sides. The double-sided pressure-sensitive adhesive tape or sheet 1 has the same configuration as that shown in FIG.

  The separator in the laminated tape or sheet of the present invention has peelability. Examples of the laminated structure of the separator include (i) a single-layer structure including only a base material, and (ii) a structure including two or more layers in which a base material and a release layer are sequentially formed. Here, the separator includes at least a base material.

  In the above aspect (i), the substrate is preferably made of a material having high peelability. In the above aspect (ii), the base material may be made of a material having high peelability, or may be made of a material having low peelability. When the substrate is made of a material having low peelability, a release layer is preferably formed on one side and / or both sides of the substrate.

  As a material constituting the substrate, ethylene (including low density polyethylene, high density polyethylene, linear low density polyethylene, etc.), ethylene-α-olefin copolymer such as polypropylene, ethylene-propylene copolymer ( Block copolymer or random copolymer), and Teflon (registered trademark). The material contained in the substrate may be one kind or two or more kinds. As the separator, for example, a commercially available release film may be employed. The release layer can be formed of the same material as the release treatment agent.

  The thickness of the separator is not particularly limited, and can be in an appropriate range depending on the purpose of use and the like.

  The separator can be provided, for example, so as to cover all the surfaces of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer that are respectively arranged in the outermost layer of the laminate. The separator that covers the first pressure-sensitive adhesive layer is sometimes referred to as a first separator, and the separator that covers the second pressure-sensitive adhesive layer is sometimes referred to as a second separator.

  In the laminated tape or sheet, when the separator is formed only on the outer side of the adhesive layer on one side of the double-sided adhesive tape or sheet, the laminated tape or sheet comprises the first separator, the first adhesive layer, and the support. The second pressure-sensitive adhesive layer has a structure laminated in this order. In this case, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, which are the outermost layers of the laminate, are obtained by having the first separator so as to be wound in a roll shape in the longitudinal direction. Since it is protected by the first separator, blocking between the laminates is prevented.

  When the separator is formed only on the outside of the double-sided pressure-sensitive adhesive tape or the pressure-sensitive adhesive layer on one side of the sheet, in order to prevent the separator from being unexpectedly peeled off when being drawn out from the wound state, etc. The peel force on both sides of the first separator (that is, the peel force between the first pressure-sensitive adhesive layer and the first separator and the peel force between the second pressure-sensitive adhesive layer and the second separator) Preferably they are not the same. It is preferable that the separator is composed of two or more layers in which the base material and the release layer are sequentially formed, so that the peeling forces on both surfaces can be easily made different. In addition, when it is difficult to make the peeling force of both surfaces different from each other when the first separator having a single-layer structure only is used, the adhesion between the first adhesive layer and the second adhesive layer The power may be different.

  In the laminated tape or sheet, when the separator is formed on the outer side of each of the double-sided pressure-sensitive adhesive tape or the double-sided pressure-sensitive adhesive layer of the sheet, the laminated tape or sheet comprises the first separator, the first pressure-sensitive adhesive layer, and the support. The second pressure-sensitive adhesive layer and the second separator have a structure laminated in this order. In this case, since the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer which are the outermost layers of the laminate are respectively protected by the first separator and the second separator, they are wound in a roll shape in the longitudinal direction. When the state is changed, blocking between the laminated bodies is prevented. Moreover, it can use for various shapes, such as strip shape and flat plate shape.

  When the separator is formed on the outer side of each of the double-sided pressure-sensitive adhesive tape or the double-sided pressure-sensitive adhesive layer of the sheet, in order to make it easier to peel the separator sequentially than the double-sided pressure-sensitive adhesive tape or sheet, It is preferable that (the peeling force between the first separator and the first pressure-sensitive adhesive layer and the peeling force between the second separator and the second pressure-sensitive adhesive layer) are not the same. Or you may make it make the adhesive force of a 1st adhesive layer and a 2nd adhesive layer differ.

3. Method for producing double-sided pressure-sensitive adhesive tape or sheet The method for producing the above double-sided pressure-sensitive adhesive tape or sheet is not particularly limited. For example, a double-sided pressure-sensitive adhesive tape or a double-sided pressure-sensitive adhesive tape according to a production method comprising a step of forming the support with a raw material containing a polypropylene resin and a step of forming the pressure-sensitive adhesive layer with a composition for forming a pressure-sensitive adhesive layer containing a polyolefin-based pressure-sensitive adhesive. Sheets can be manufactured. The obtained double-sided pressure-sensitive adhesive tape or sheet has a total thickness (Ds) of the laminate of 2.5 to 12 μm, and a ratio Dp / Ds between the thickness (Dp) of the support and the total thickness (Ds) of the laminate. Of 0.3 to 0.8.

  The process of forming the said support body with the raw material containing a polypropylene resin can be set as the same structure as the above-mentioned "support body formation process."

  Moreover, although the above-mentioned polypropylene resin composition is used in a support body formation process, it is preferable that melting | fusing point of this polypropylene resin is 155-180 degreeC especially. In this case, the melting point of the formed support can be increased, and the dielectric breakdown voltage of the double-sided pressure-sensitive adhesive tape or sheet can be improved. The melting point of the polypropylene resin is 155 to 180 ° C., which is the same definition as described above.

  Moreover, it is preferable that a raw material contains 80-100 mass% of isotactic homopolypropylene whose mesopentad fraction is 90-99.5% with respect to the whole quantity of the said raw material. In this case, the strength of the double-sided pressure-sensitive adhesive tape or sheet to be obtained can be improved, and further, the dielectric breakdown voltage can be improved, so that it is easy to produce a double-sided pressure-sensitive adhesive tape or sheet having excellent durability. In particular, when the isotactic homopolypropylene having a mesopentad fraction of 93.5 to 99.5% is contained in an amount of 80 to 100% by mass, the dielectric breakdown voltage is further improved.

  When the raw material containing polypropylene resin contains isotactic homopolypropylene having a mesopentad fraction of 90 to 99.5%, the melt mass flow rate (MFR) of this isotactic homopolypropylene is 1.5 to 6 g / 10. Minutes are preferred. Since the support formed of such isotactic homopolypropylene has excellent stretchability, it is easy to adjust the thickness of the target double-sided pressure-sensitive adhesive tape or sheet. The melt flow rate (MFR) here is a value measured under the same measurement conditions as described above.

  The step of forming the pressure-sensitive adhesive layer using the pressure-sensitive adhesive layer-forming composition containing the polyolefin-based pressure-sensitive adhesive is the same as the above-mentioned “pressure-sensitive adhesive layer forming step”. For example, when the pressure-sensitive adhesive layer is formed by coating, the pressure-sensitive adhesive layer can be formed using the pressure-sensitive adhesive layer forming composition.

  You may form an adhesive layer by apply | coating the composition for adhesive layer formation to both surfaces of a support body, for example. Thereby, a laminated body can be obtained.

  Or you may form an adhesive layer on the said separator. After the pressure-sensitive adhesive layer is formed on the separator, the surface of the separator on the pressure-sensitive adhesive layer side is bonded to the support. Thereby, a laminated tape or sheet is obtained, and a double-sided pressure-sensitive adhesive tape or sheet is obtained by peeling the separator from the obtained laminated tape or sheet.

  As an example of a method for producing a double-sided pressure-sensitive adhesive tape or sheet, the step of forming the pressure-sensitive adhesive layer on the separator and the surface on the side where the pressure-sensitive adhesive layer of the separator is formed on one side or both sides of the support are bonded. The manufacturing method provided with a process is mentioned. More specifically, two separators having the pressure-sensitive adhesive layer formed as described above are prepared (referred to as a first separator and a second separator, respectively), and the first separator is placed on one surface of the support. The second separator is bonded to the other surface of the support. By laminating the surface of each separator on the pressure-sensitive adhesive layer side to a support, a laminated tape or sheet having separators on both sides is obtained. Note that the second separator is not necessarily prepared, and only the first separator may be bonded to one side of the support.

  Then, a double-sided pressure-sensitive adhesive tape or sheet is obtained through a step of peeling the double-sided or single-sided separator from the laminated tape or sheet. The obtained double-sided pressure-sensitive adhesive tape or sheet includes a laminate comprising a support and two pressure-sensitive adhesive layers formed on both sides of the support.

  According to the said manufacturing method, a double-sided adhesive tape or a sheet | seat can be manufactured by a simple method.

  The separator used here has the same configuration as described above. What is necessary is just to apply | coat the application amount of the composition for adhesive layer formation to a separator so that it may form with the thickness (for example, 0.5-4 micrometers) of the above-mentioned adhesive layer after drying. The method of application is not particularly limited, and for example, various application apparatuses can be used. Examples of the coating apparatus include a roll coater, a Mayer bar coater, a kiss roll coater, a gravure coater, a rod coater, a blade coater, and an air knife coater. After application, drying, curing, and the like can be performed under appropriate conditions.

  In the double-sided pressure-sensitive adhesive tape or sheet of the present invention produced as described above, the support contains a polypropylene resin, the total thickness (Ds) of the laminate, and the ratio of the thickness of the support to the total thickness (Dp / Ds ) Is in a specific range, it is excellent in strength, adhesiveness and insulation even at a thin thickness, and also has excellent electrolyte resistance. In particular, since the support includes a polypropylene resin, the electrolyte resistance is superior to that of a conventional double-sided pressure-sensitive adhesive tape or sheet. For example, even when used as a constituent member of a secondary battery, the electrolyte contained in the secondary battery Degradation and damage due to etc. hardly occur. In addition, the double-sided pressure-sensitive adhesive tape or sheet of the present invention is excellent in strength and insulation even in a thin thickness, and is particularly suitable for use in electronic parts, optical parts, etc. in addition to various batteries represented by small secondary batteries. it can. Specifically, the use of the double-sided pressure-sensitive adhesive tape or sheet of the present invention is, for example, in a battery in which an electrolytic solution such as a lithium ion battery is enclosed, for the purpose of improving the suitability of electrodes in the battery case, and present in the electrode plate The use for the purpose of preventing the short circuit between electrodes caused by the burr | flash etc. which do pass through a separator is mentioned.

  In the laminated tape or sheet of the present invention, blocking of the double-sided pressure-sensitive adhesive tape or sheet having the above excellent effects is protected. Moreover, the laminated tape or sheet of this invention can use the said double-sided adhesive tape or sheet | seat efficiently by peeling a separator.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the aspect of these Examples.

Example 1
Prime polymer isotactic homopolypropylene resin having an MFR of 4.5 and a mesopentat fraction of 94% was fed to an extruder and melted at 240 ° C. Thereafter, the melted polypropylene resin was extruded using a T-die, and then cooled and solidified on a metal drum maintained at a surface temperature of 60 ° C. to produce a cast raw sheet having a thickness of about 120 μm. This cast original fabric sheet was stretched 5 times in the flow direction at 145 ° C., then stretched 10 times in the transverse direction at 160 ° C. by a tenter, and then relaxed to 9.5 times. Thereafter, corona treatment was performed on both sides to obtain a biaxially stretched polypropylene film having a thickness of 2.5 μm as a support.

  On the other hand, the first separator wound in the form of a roll is fed out, and with respect to one surface of the first separator, as a pressure-sensitive adhesive layer forming composition, toluene is used so that the solid content concentration becomes 10%. Diluted “Unistor (registered trademark) R-300” manufactured by Mitsui Chemicals, Inc. was applied by a roll coater and then dried at 100 ° C. As a result, a first pressure-sensitive adhesive layer having a thickness of 1 μm was formed on the first separator. The pressure-sensitive adhesive layer forming composition used includes an acid-modified polyolefin resin as a polyolefin-based pressure-sensitive adhesive. Further, the surface of the first pressure-sensitive adhesive layer, which is the surface where the first pressure-sensitive adhesive layer and the first separator are in contact with each other, is also referred to as the “first pressure-sensitive adhesive layer peeling surface”. A surface of the layer that contacts the first pressure-sensitive adhesive layer and a support described later is also referred to as a “support-bonding surface of the first pressure-sensitive adhesive layer”.

  Next, the biaxially stretched polypropylene film as a support was drawn out, and this one surface was bonded onto the first pressure-sensitive adhesive layer formed on the first separator. This obtained the 1st multilayer body by which a 1st separator, a 1st adhesive layer, and a support body (biaxially-stretched polypropylene film) are arrange | positioned in order. In addition, it is the surface of a support body, Comprising: The surface where the said 1st adhesive layer and the said support body contact is also called "support body surface 1", It is a surface of a support body, Comprising: The below-mentioned 2nd adhesive layer and The surface in contact with the support is also referred to as “support surface 2”.

  On the other hand, the second separator wound in a roll shape is fed out, and the same adhesive layer forming composition as above is applied to one surface of the second separator with a roll coater, and then 100 ° C. And dried to form a second pressure-sensitive adhesive layer having a thickness of 1 μm. This obtained the 2nd multilayer body by which a 2nd separator and a 2nd adhesive layer are arrange | positioned in order. The surface of the second pressure-sensitive adhesive layer where the second pressure-sensitive adhesive layer and the second separator are in contact with each other is also referred to as the “second pressure-sensitive adhesive layer peeling surface”. The surface of the layer that contacts the second pressure-sensitive adhesive layer and the support described above or described later is also referred to as a “support-bonding surface of the second pressure-sensitive adhesive layer”.

  Subsequently, a laminated sheet was produced by bonding the first multilayer body and the second multilayer body together. Specifically, the first multilayer body and the second multilayer body are in contact with each other so that the support surface 2 in the first multilayer body and the support adhesive surface of the second pressure-sensitive adhesive layer in the second multilayer body are in contact with each other. The multilayer body was bonded together.

  Then, it wound up in roll shape and produced the lamination sheet. The laminated sheet is formed by laminating a first separator, a first pressure-sensitive adhesive layer, a support, a second pressure-sensitive adhesive layer, and a second separator in this order. Moreover, the laminated body, ie, a double-sided adhesive sheet, is formed with the 1st adhesive layer, the support body, and the 2nd adhesive layer. The total thickness Ds of the laminate was 4.5 μm.

(Examples 2-7, Comparative Examples 1-4)
As shown in Table 1, in Example 1, except that one or more conditions of the thickness of the support, the thickness of the pressure-sensitive adhesive layer, and the type of polypropylene resin constituting the support were changed, Example 1 and A laminated sheet was obtained in the same manner.

(Comparative Example 5)
Laminated sheet in the same manner as in Example 1 except that polyethylene terephthalate (PET) resin was used instead of isotactic homopolypropylene resin and the thickness of the support and the thickness of the adhesive layer were changed as shown in Table 1. Got.

  Table 1 shows the type and physical properties of the resin used to form the support, the thickness Dp of the support, the thickness of the pressure-sensitive adhesive layer, the total thickness Ds of the laminate, and the ratio of the thickness of the support and the total thickness of the laminate. (Dp / Ds), breaking stress of the laminate, dielectric breakdown voltage of the laminate, initial tackiness of the double-sided PSA sheet, and electrolyte resistance are shown. The “thickness of the pressure-sensitive adhesive layer” shown in Table 1 is the thickness value of each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.

  From the comparison of Examples 1-7 and Comparative Examples 1-5, the double-sided pressure-sensitive adhesive sheet in which the total thickness Ds of the laminate is 2.5 to 12 μm and the value of Dp / Ds is 0.3 to 0.8. It can be seen that it is excellent in strength, adhesiveness and insulation, and also excellent in electrolyte resistance. In Comparative Example 1, since the value of the total thickness Ds was too small, wrinkles were generated at the time of bonding, and it was difficult to obtain a double-sided PSA sheet. In Comparative Example 2, the total thickness Ds satisfies a specific range, but the strength is low because the value of Dp / Ds is too small. In Comparative Example 3, the total thickness Ds satisfied a specific range, but since the value of Dp / Ds was too large, a decrease in initial tackiness was observed. In Comparative Example 4, since the value of the total thickness Ds was small and the value of Dp / Ds was too large, a decrease in initial adhesiveness was observed. In Comparative Example 5, since the support was made of PET, the strength and adhesiveness were good, but it was found that the dielectric breakdown voltage was low and there was a problem with the electrolyte resistance. In Comparative Examples 3 and 4, the initial adhesiveness was poor, and the electrolyte resistance was not evaluated.

  From the above, the double-sided pressure-sensitive adhesive tape or sheet of the present invention is excellent in strength, adhesiveness and insulation even if the thickness is thin, and also excellent in electrolyte resistance and can be made extremely thin. It was shown that it can be suitably used particularly for a thin secondary battery or the like.

<Evaluation method>
[Melting mass flow rate of resin (MFR)]
According to JIS K-7210 (1999), the measurement was performed under the conditions of a measurement temperature of 230 ° C. and a load of 21.18 N using a melt indexer manufactured by Toyo Seiki Seisakusho.

[Resin melting peak]
Calculation was performed by the following procedure using an input compensation DSC and Diamond DSC manufactured by Perkin Elmer. 5 mg of measurement resin (resin as a raw material) was weighed, packed in an aluminum sample holder, and set in a DSC apparatus. Under a nitrogen flow, the temperature was raised from 30 ° C. to 280 ° C. at a rate of 20 ° C./minute, held at 280 ° C. for 5 minutes, cooled to 30 ° C. at 20 ° C./minute, and held at 30 ° C. for 5 minutes. Thereafter, the melting point was determined from the DSC curve when the temperature was raised again to 280 ° C. at 20 ° C./min. The melting peak defined in 9.1 (1) of JIS-K7121 (the maximum melting peak when a plurality of melting peaks is shown) was measured to determine the melting point.

[Thickness]
The total thickness of the laminated sheets (first separator, first pressure-sensitive adhesive layer, support, second pressure-sensitive adhesive layer, second separator, which is a five-layer structure) obtained in Examples and Comparative Examples, It measured based on JIS-C2330 using the Yamabun Electric Co., Ltd. desktop type contact-type thickness meter TOF-5R01.

  Moreover, the thickness of a support body, an adhesive layer, and a separator was computed using the total thickness of the said laminated sheet, and the ratio of each layer and total thickness of a laminated sheet. This ratio was calculated | required by measuring the image observed with the microscope for the test piece for cross-sectional observation obtained by cut | disconnecting a lamination sheet with the vertical slicer HS-1 by JASCO Corporation.

  Then, by adding the thicknesses of the support, the first pressure-sensitive adhesive layer, and the second pressure-sensitive adhesive layer measured as described above, a laminate (first pressure-sensitive adhesive layer, support, second pressure-sensitive adhesive) is obtained. The total thickness Ds of the agent layer was calculated.

[Breaking stress]
In accordance with JISK-7127 (1999), the sample shape conforms to specimen type 2 (sample width 15 mm, sample length 150 mm), and tensile tester (Universe Tensile Tester Technograph TGI- manufactured by Minebea Co., Ltd.) 1 kN) was used. The stress at break was measured in the width direction and the flow direction under the conditions of 23 ° C., a test speed of 120 mm / min, and a distance between chucks of 60 mm. When measuring the tensile modulus and elongation in the flow direction, using a test piece cut out with a length of 150 mm in the flow direction and a width of 15 mm in the width direction, when measuring the tensile modulus and elongation in the width direction, Measurement was performed using a test piece cut out with a length of 150 mm in the width direction and a width of 15 mm in the flow direction.

  The test piece was cut out in the state of a laminated sheet (having a five-layer structure of a first separator, a first pressure-sensitive adhesive layer, a support, a second pressure-sensitive adhesive layer, and a second separator). In addition, the measurement is performed by sandwiching one end of the test piece with the chuck part at the upper part of the tensile tester and then the other end with the first separator and the second separator peeled off from the laminate. Then, the first separator and the second separator were peeled up to the upper chuck part and bent outward, and the separator was not in contact with the laminate at the measurement part between the upper and lower chucks.

[Dielectric breakdown voltage]
The first separator from the laminated sheets (first separator, first pressure-sensitive adhesive layer, support, second pressure-sensitive adhesive layer, and second separator) obtained in the examples and comparative examples. Was peeled off, and the first pressure-sensitive adhesive layer that appeared on the surface was attached to the aluminum foil as the lower electrode. Further, the second separator is peeled off, an upper electrode is placed on the surface of the second pressure-sensitive adhesive layer that appears on the surface, and in accordance with JIS C2330 (2001) 7.4.111.2 B method (flat plate electrode method). The dielectric breakdown voltage value was measured 12 times at 100 ° C. using a DC power source. For the measurement, a DC withstand voltage / insulation resistance tester TOS9213AS manufactured by Kikusui Electronics Corporation was used. The average value of 8 times excluding the upper 2 times and the lower 2 times among the 12 measurement results was taken as the dielectric breakdown voltage (kV).

[Initial tack]
From the laminated sheets (first separator, first pressure-sensitive adhesive layer, support, second pressure-sensitive adhesive layer, and second separator five-layer configuration) obtained in the examples and comparative examples, a width of 10 mm, A test piece having a length of 125 mm was cut out. The first separator of the test piece was peeled off, and a biaxially stretched polypropylene film having a width of 10 mm, a length of 25 mm, and a thickness of 30 μm was bonded onto the first pressure-sensitive adhesive layer at one end thereof to form a grip portion. A first pressure-sensitive adhesive layer (length 100 mm) other than the grip portion was bonded to the aluminum foil surface by applying a pressure of 0.2 MPa at 130 ° C. for 2 seconds to obtain a test specimen.

After peeling the second separator from this specimen, use a tensile testing machine (Universe Tensile Tester Technograph TGI-1kN, manufactured by Minebea Co., Ltd.), and sandwich the grip part of the specimen with the chuck part, and the aluminum foil surface The peel adhesive strength at the time of peeling the laminate was measured (180 ° peeling, normal temperature (25 ° C.), peeling speed: 300 mm / min) to determine the initial adhesive strength of the film, and evaluated according to the following criteria.
(Double-circle): The adhesive force was measurable and the said adhesive force was 0.5 N or more (usable).
(Even if the aluminum foil was destroyed at the time of peel adhesion measurement, it was judged as ◎)
○: The adhesive strength could be measured, and the adhesive strength was less than 0.5N (can be used).
X: The laminate did not adhere to the aluminum foil, or peeled off easily and the adhesive strength could not be measured.

[Electrolytic resistance]
An electrolyte solution having a concentration of 1 mol / l was prepared by adding lithium hexafluoride lithium salt (LiPF ₆ ) to a mixed solution of ethylene carbonate: diethyl carbonate in a weight ratio of 1: 1. The test body was produced in the same procedure as the above-mentioned initial adhesiveness. After peeling the second separator from the obtained test specimen, the specimen was immersed in 100 ml of the electrolyte solution and sealed, and kept at 40 ° C. for 7 days. Thereafter, the specimen specimen from which the laminate did not peel was lifted from the electrolyte solution. Then, ethylene carbonate: diethyl carbonate was washed with a mixed solution at a weight ratio of 1: 1 and air-dried. When the sample after immersion is peeled off from the aluminum foil surface using a tensile tester (Universal Tensile Tester Technograph TGI-1kN, manufactured by Minebea Co., Ltd.) The peel adhesive strength (180 ° peeling, normal temperature (25 ° C.), peeling speed: 300 mm / min) was measured. The measurement result was compared with an unimmersed sample, the rate of decrease from the initial adhesive strength was calculated, and the electrolyte resistance was evaluated according to the following criteria.
◎ There was no peeling of the laminate from the aluminum foil, the rate of decrease in adhesive strength was less than 30%, and it had excellent electrolyte resistance. (Although the aluminum foil was destroyed when measuring the peel strength, ◎ ).
○ Although the laminate was not peeled from the aluminum foil and the rate of decrease in adhesive strength was 30% or more, it had electrolyte resistance.
X The laminate was peeled off from the aluminum foil and did not have electrolyte resistance.

1: Double-sided adhesive tape or sheet 10: Laminate 11: Support 12: Adhesive layer 12a: First adhesive layer 12b: Second adhesive layer 13: Separator 2: Laminated tape or sheet Ds: Laminate Total thickness Dp: thickness of support

Claims (10)

A double-sided pressure-sensitive adhesive tape or sheet comprising a support and a laminate composed of two pressure-sensitive adhesive layers formed on both sides of the support,
The support includes a polypropylene resin,
The pressure-sensitive adhesive layer contains a polyolefin-based pressure-sensitive adhesive,
The total thickness (Ds) of the laminate is 2.5 to 12 μm,
The double-sided pressure-sensitive adhesive tape or sheet, wherein the value of the ratio Dp / Ds between the thickness (Dp) of the support and the total thickness (Ds) of the laminate is 0.3 to 0.8.   The double-sided pressure-sensitive adhesive tape or sheet according to claim 1, wherein the support has a thickness (Dp) of 1.5 to 6 μm.   The double-sided pressure-sensitive adhesive tape or sheet according to claim 1 or 2, wherein both the breaking strength in the flow direction and the breaking strength in the width direction of the laminate are 50 to 260 MPa.   The double-sided adhesive tape or sheet of any one of Claims 1-3 whose dielectric breakdown voltage of the said laminated body is 1-8 kV.   The double-sided pressure-sensitive adhesive tape or sheet according to any one of claims 1 to 4, wherein the support is a biaxially stretched polypropylene film.   The double-sided pressure-sensitive adhesive tape or sheet according to any one of claims 1 to 5, wherein the polypropylene resin has a melting point of 155 to 180 ° C.   The said support body contains 80-100 mass% of isotactic homopolypropylenes whose mesopentad fraction is 90-99.5% with respect to the total mass of this support body, The any one of Claims 1-6 The double-sided pressure-sensitive adhesive tape or sheet according to Item.   The double-sided pressure-sensitive adhesive tape or sheet according to claim 7, wherein a melt mass flow rate (MFR) of the isotactic homopolypropylene is 1.5 to 6 g / 10 minutes. A double-sided pressure-sensitive adhesive tape or sheet according to any one of claims 1 to 8, and a separator,
The separator is a laminated tape or sheet formed outside the pressure-sensitive adhesive layer on at least one side of the double-sided pressure-sensitive adhesive tape or sheet.   The laminated tape or sheet according to claim 9, wherein the separator is formed on an outer side of each of the pressure-sensitive adhesive layers on both sides.