JP5828732B2 - Base material for double-sided adhesive tape - Google Patents

Description

  The present invention relates to a double-sided pressure-sensitive adhesive tape substrate.

  A double-sided pressure-sensitive adhesive tape having a base material and a pressure-sensitive adhesive impregnated on both surfaces of the base material is used for fixing an article to another article. As a base material for this double-sided pressure-sensitive adhesive tape, generally, a sheet or a film formed from a polyester resin is used in addition to paper obtained by making pulp fibers.

  Such a double-sided pressure-sensitive adhesive tape is also used for fixing components of electronic equipment, and when used in electronic equipment, excellent adhesiveness is required. In recent years, with the miniaturization of electronic devices, the double-sided adhesive tape is also required to be thin. In double-sided pressure-sensitive adhesive tapes used for such applications, pressure-sensitive adhesive tape base materials with good pressure-sensitive adhesive properties are required in order to increase the adhesive strength, and the use of polyester base materials that can be made into uniform sheets with small thickness unevenness has increased. Yes. For example, a base material for pressure-sensitive adhesive tapes has been devised that has a particularly high stretchability and that has a good texture and allows the pressure-sensitive adhesive to penetrate evenly by blending unstretched polyester fibers and stretched polyester fibers (Japanese Patent Laid-Open No. 2010-180513, etc.) reference).

  However, although the adhesive tape substrate disclosed in the above publication is excellent in adhesive permeability and stretchability, it seems to be used for fixing small electronic devices such as mobile phones and components such as thin televisions. When the thickness is reduced, the tensile strength of the base material for the adhesive tape is lowered, and the workability and handleability are lowered. In addition, if the adhesive tape substrate after papermaking is heat calendered to improve the decrease in tensile strength, the gaps between the fibers become smaller and the density becomes higher, and the permeability of the adhesive decreases, resulting in higher adhesive strength. I can't. For this reason, the above-described requirements cannot be sufficiently satisfied.

JP 2010-180513 A

  The present invention has been made on the basis of the above-described circumstances, and has a low basis weight and a small paper thickness, and has excellent adhesive permeability and sufficient tensile strength. The purpose is to provide.

The invention made to solve the above problems is
It is obtained by papermaking a raw material mainly composed of polyester core-sheath structure fiber and polyester unstretched single structure fiber,
It is a base material for double-sided pressure-sensitive adhesive tapes having a basis weight of 3 g / m ^{2 to} 8 g / m ² and a paper thickness of 15 μm to 40 μm.

  The base material for the double-sided pressure-sensitive adhesive tape is made by making a paper mainly composed of a polyester-sheath structure fiber having heat-fusibility and an unstretched single-structure fiber made of polyester having heat-fusibility, Since the fibers constituting the base material are easily oriented randomly and the gaps between the fibers are increased, the base material can be a low density and uniform base material with a low basis weight. In addition, since the sheath part of the core-sheath structure fiber and the unstretched single structure fiber are bonded after being fused in the dryer process at the time of papermaking, the fibers are strongly bonded to each other, so that they have sufficient tensile strength even at low basis weight. be able to. Therefore, even if the basis weight and the paper thickness are as small as the above ranges, the base material for the double-sided pressure-sensitive adhesive tape can exhibit excellent permeability of the pressure-sensitive adhesive and have sufficient tensile strength.

  Further, by using the above-described polyester core-sheath structure fiber and unstretched single structure fiber, it is possible to make a paper for a double-sided pressure-sensitive adhesive tape substrate having a low basis weight and a small paper thickness without performing a heat calendering process. it can. Therefore, the base material for double-sided pressure-sensitive adhesive tape can omit thermal calendering after paper making, and can suppress the density to be low and increase the permeability of the pressure-sensitive adhesive. Furthermore, when thermal calendar processing is not performed after papermaking, productivity of the base material for double-sided pressure-sensitive adhesive tape can be improved.

  The fineness of the core-sheath structure fiber is 1.1 dtex or more and 2.2 dtex or less, the fiber length is 3 mm or more and 10 mm or less, the fineness of the unstretched single structure fiber is 0.1 dtex or more and 1.2 dtex or less, and the fiber length is 1 mm. The fineness of the core-sheath structure fiber is preferably greater than the fineness of the unstretched single structure fiber. By increasing the fineness and fiber length of the core-sheath structure fiber and the unstretched single structure fiber within the above range, the gap between the fibers constituting the base material is increased while increasing the entanglement between the fibers and increasing the adhesive strength. Can do. As a result, the base material for a double-sided pressure-sensitive adhesive tape can have further excellent adhesive permeability and tensile strength.

  It is preferable that the content of the core-sheath structure fiber is 50% by mass or more and 90% by mass or less, and the content of the unstretched single structure fiber is 10% by mass or more and 50% by mass or less. By setting the content ratios of the core-sheath structure fiber and the unstretched single structure fiber in the above range, the gap between the fibers can be maintained even with a low basis weight, and the adhesive strength between the fibers can be further increased. As a result, the base material for a double-sided pressure-sensitive adhesive tape can have further excellent adhesive permeability and tensile strength.

The base material for the double-sided pressure-sensitive adhesive tape has a density of 0.1 g / cm ³ or more and 0.25 g / cm ³ or less, an air permeability of 0.8 sec / 300 ml · 100 sheets or less, and a tensile strength of 67 N / It is good that it is m or more. By setting the density and air permeability of the base material for double-sided pressure-sensitive adhesive tape within the above ranges, the base material for double-sided pressure-sensitive adhesive tape can have higher permeability. In addition, by setting the tensile strength within the above range, the double-sided pressure-sensitive adhesive tape substrate has good workability and handleability in which paper breakage hardly occurs even when the paper has a low basis weight and a small paper thickness.

  Here, “basis weight” is a value measured according to JIS-P8124. “Paper thickness” and “density” are values measured in accordance with JIS-P8118. “Fineness” is a value measured according to JIS-L1095. “Fiber length” means a number average fiber length, and is a value measured in accordance with JIS-P8226. “Air permeability” is a value obtained by measuring the time (seconds) required for 300 ml of air to pass through 100 sheets of double-sided adhesive tape substrates in accordance with JIS-P8117. “Tensile strength” means the tensile strength in the longitudinal direction of the substrate for double-sided pressure-sensitive adhesive tape, and is a value measured according to JIS-P8113.

  As described above, the base material for double-sided pressure-sensitive adhesive tape of the present invention is excellent in the permeability of the pressure-sensitive adhesive and has a sufficient tensile strength even when having a low basis weight and a small paper thickness. Therefore, it can be suitably used as a substrate for a thin double-sided pressure-sensitive adhesive tape particularly used for fixing small electronic devices such as mobile phones and thin TV components.

  Hereinafter, embodiments of the present invention will be described in detail.

The base material for a double-sided pressure-sensitive adhesive tape of the present invention is obtained by papermaking a raw material mainly composed of a polyester-sheath structure fiber and a polyester unstretched single structure fiber, and has a basis weight of 3 g / m. ^{2 to} 8 g / m ² or less, and the paper thickness is 15 μm or more and 40 μm or less.

  The base material for the double-sided pressure-sensitive adhesive tape is made of paper mainly composed of a polyester-sheath structure fiber having heat-fusibility and an unstretched single-structure fiber made of polyester having heat-fusibility. Since the fibers constituting the base material are easily oriented randomly and the gaps between the fibers are increased, the base material can be a low density and uniform base material with a low basis weight. In addition, since the sheath part of the core-sheath structure fiber and the unstretched single structure fiber are bonded after being fused in the dryer process at the time of papermaking, the fibers are strongly bonded to each other, so that they have sufficient tensile strength even at a low basis weight. be able to. Therefore, even if the basis weight and the paper thickness are as small as the above ranges, the base material for the double-sided pressure-sensitive adhesive tape can exhibit excellent permeability of the pressure-sensitive adhesive and have sufficient tensile strength. Therefore, it can be suitably used as a substrate for thin double-sided pressure-sensitive adhesive tapes used for fixing small electronic devices such as mobile phones and thin TV components.

  Hereafter, the raw material suitable for comprising the said base material for double-sided adhesive tapes, and the manufacturing method of the said base material for double-sided adhesive tapes are demonstrated.

<Polyester fiber>
The material of the polyester fiber (core-sheath structure fiber, unstretched single structure fiber) that can be used for the base material for the double-sided adhesive tape is not particularly limited as long as it is polyester. For example, polyethylene terephthalate, poly Polyester fibers composed of glycol / dicarboxylic acid polycondensation systems such as butylene terephthalate, polyethylene succinate and polybutylene succinate, polylactides such as polyglycolic acid and polylactic acid, polylactones and the like can be used. Among these, polyethylene terephthalate having a good balance of various functions such as heat resistance and weather resistance and a price is particularly preferable.

<Core sheath fiber>
As for the core-sheath structure fiber used for the said base material for double-sided adhesive tapes, a core part and a sheath part are comprised with the above-mentioned polyester fiber.

  The fineness of the core-sheath structure fiber is preferably 1.1 dtex or more and 2.2 dtex or less, and more preferably 1.5 dtex or more and 2.0 dtex or less. When the fineness of the core-sheath structure fiber is less than 1.1 dtex, there is a possibility that the gap between the fibers decreases and the permeability of the pressure-sensitive adhesive deteriorates. On the contrary, when the fineness of the core-sheath structure fiber exceeds 2.2 dtex, the entanglement between the fibers decreases and the adhesive strength becomes weak, and the tensile strength of the base material for the double-sided pressure-sensitive adhesive tape may be lowered, or papermaking cannot be performed. There is a fear.

  The length of the core-sheath structure fiber is preferably 3 mm or more and 10 mm or less, and more preferably 4 mm or more and 7 mm or less. When the length of the core-sheath structure fiber is less than 3 mm, there is a possibility that the gap between the fibers decreases and the permeability of the pressure-sensitive adhesive deteriorates. On the contrary, when the length of the core-sheath structure fiber exceeds 10 mm, the entanglement between the fibers decreases and the adhesive strength becomes weak, and the tensile strength of the base material for the double-sided pressure-sensitive adhesive tape may be lowered. There is a possibility that the amount of water increases, or dispersibility in water becomes unfavorable, and it becomes difficult to obtain a uniform web.

  As for melting | fusing point of the sheath part of this core-sheath structure fiber, 110 to 140 degreeC is preferable. If the melting point of the sheath is less than 110 ° C., fibers may stick to the dryer when the base material for the double-sided pressure-sensitive adhesive tape is made, and productivity may be reduced. On the contrary, when the melting point of the sheath exceeds 140 ° C., the sheath does not melt in the dryer process at the time of paper making of the double-sided adhesive tape substrate, and the fibers are not bonded. There is a possibility that it does not have a good tensile strength.

  As for melting | fusing point of the core part of the said core-sheath structure fiber, 150 degreeC or more is preferable. If the melting point of the core is less than 150 ° C., the entire core-sheath structure fiber melts in the dryer process during papermaking of the double-sided adhesive tape substrate, and the tensile strength of the double-sided adhesive tape substrate may decrease, There is a possibility that the base material becomes a film and the gap between the fibers is reduced and the permeability of the pressure-sensitive adhesive is deteriorated.

  The ratio of the mass of the sheath portion to the mass of the core portion of the core-sheath structure fiber is preferably 0.2 or more and 3 or less. If the ratio of the mass of the sheath portion to the mass of the core portion of the core-sheath structure fiber is less than 0.2, the adhesive strength of the core-sheath structure fiber is insufficient, and the tensile strength of the double-sided pressure-sensitive adhesive tape substrate may be reduced. is there. Conversely, if the ratio of the mass of the sheath portion to the mass of the core portion of the core-sheath structure fiber exceeds 3, the melted portion of the core-sheath structure fiber increases, and the tensile strength of the base material for double-sided pressure-sensitive adhesive tape decreases. There is a possibility that the gap between the fibers decreases and the permeability of the pressure-sensitive adhesive deteriorates.

<Unstretched single structure fiber>
The unstretched single structure fiber used for the base material for double-sided pressure-sensitive adhesive tape is the above-described polyester fiber that has not been stretched after spinning, and is a single structure fiber that does not have a core-sheath structure. Since unstretched single structure fibers have irregular molecules, the fibers soften when heated, and thus have an adhesive property. When this unstretched single-structure fiber is used, the fiber softens and adheres in the dryer process during papermaking, but does not melt, so that the tensile strength can be improved while maintaining the gaps between the fibers.

  The fineness of the unstretched single structure fiber is preferably from 0.1 dtex to 1.2 dtex, more preferably from 0.15 dtex to 0.5 dtex. When the fineness of the unstretched single structure fiber is less than 0.1 dtex, there is a possibility that the gap between the fibers decreases and the permeability of the pressure-sensitive adhesive deteriorates. On the contrary, when the fineness of the unstretched single structure fiber exceeds 1.2 dtex, the entanglement between the fibers decreases and the adhesive strength becomes weak, and the tensile strength of the base material for the double-sided pressure-sensitive adhesive tape may be reduced. You may not be able to. Furthermore, by making the fineness of the unstretched single structure fiber smaller than the fineness of the core-sheath structure fiber, that is, by making the fineness of the core-sheath structure fiber larger than the fineness of the unstretched single-structure fiber, It is preferable because the fiber and the unstretched single structure fiber are easily entangled and the tensile strength can be increased while maintaining the gap between the fibers. In particular, when the fineness of the core-sheath structure fiber is 0.5 dtex or more larger than the fineness of the unstretched single-structure fiber, the entanglement between the core-sheath structure fiber and the unstretched single-structure fiber is improved and the adhesive strength is increased. This is preferable because the voids can be increased.

  The length of the unstretched single structure fiber is preferably 1 mm or more and 10 mm or less, and more preferably 2 mm or more and 5 mm or less. If the length of the unstretched single structure fiber is less than 1 mm, the gap between the fibers decreases, and the permeability of the pressure-sensitive adhesive may be deteriorated or the tensile strength may be decreased. Conversely, if the length of the unstretched single structure fiber exceeds 10 mm, the entanglement between the fibers decreases and the adhesive strength becomes weak, and the tensile strength of the base material for the double-sided pressure-sensitive adhesive tape may decrease, There is a possibility that dispersion of the unstretched single-structure fibers becomes unfavorable and it is difficult to obtain a uniform web.

  As described above, in addition to using polyester core-sheath structure fibers and polyester unstretched single-structure fibers as materials and setting the paper thickness of the base material to 15 μm or more and 40 μm or less, core-sheath structure fibers The fiber fineness is 1.1 to 2.2 dtex, the fiber length is 3 mm to 10 mm, the fineness of the unstretched single structure fiber is 0.1 dtex to 1.2 dtex, the fiber length is 1 mm to 10 mm, and the core sheath By making the fineness of the structural fiber larger than that of the unstretched single structure fiber, the tensile strength is increased while maintaining the voids between the fibers, and the double-sided adhesive has excellent penetrability and sufficient tensile strength. Since the base material for tapes is obtained, it is preferable. In particular, when the fineness of the core-sheath structure fiber is 0.5 dtex or more larger than the fineness of the unstretched single-structure fiber, the entanglement between the core-sheath structure fiber and the unstretched single-structure fiber is improved and the adhesive strength is increased. This is preferable because the voids can be increased.

  The softening point of the unstretched single structure fiber is preferably 110 ° C. or higher and 140 ° C. or lower. If the softening point of the unstretched single structure fiber is less than 110 ° C., the fiber may stick to the dryer during paper making of the base material for the double-sided pressure-sensitive adhesive tape, and the productivity may decrease. There is a possibility that the voids of the adhesive are reduced and the permeability of the pressure-sensitive adhesive is deteriorated. Conversely, when the softening point of the unstretched single structure fiber exceeds 140 ° C., the unstretched single structure fiber is not softened in the dryer process during papermaking of the double-sided pressure-sensitive adhesive tape substrate, and the fiber is not bonded. There exists a possibility that the said base material for double-sided adhesive tapes may not have sufficient tensile strength.

  The crystallinity of the unstretched single structure fiber is preferably 10% or less. When the degree of crystallinity of the unstretched single-structure fiber exceeds 10%, the number of fibers that soften in the dryer process during papermaking of the base material for the double-sided pressure-sensitive adhesive tape is reduced, and the adhesive effect of the fiber is weakened. There is a possibility that the tensile strength is lowered.

  In the said base material for double-sided adhesive tapes, the content rate of core-sheath structure fiber is 50 mass% or more and 90 mass% or less, and the content rate of unstretched single structure fiber is 10 mass% or more and 50 mass% or less. It is more preferable that the content of the core-sheath structure fiber is 70% by mass or more and 85% by mass or less, and the content of the unstretched single structure fiber is 15% by mass or more and 30% by mass or less. If the content rate of a core-sheath structure fiber is less than 50 mass%, there exists a possibility that the tensile strength of the said base material for double-sided adhesive tapes may fall. On the other hand, when the content of the core-sheath structure fiber exceeds 90% by mass, voids between the fibers are decreased, and the permeability of the pressure-sensitive adhesive may be deteriorated.

  As described above, in addition to using polyester core-sheath structure fibers and polyester unstretched single-structure fibers as materials and setting the paper thickness of the base material to 15 μm or more and 40 μm or less, core-sheath structure fibers The fineness of the fiber is 1.1 to 2.2 dtex, the fiber length is 3 to 10 mm, the unstretched single structure fiber is 0.1 to 1.2 dtex, the fiber length is 1 to 10 mm, and the core By setting the content of the sheath structure fiber to 50% by mass or more and 90% by mass or less and the content of the unstretched single structure fiber to 10% by mass or more and 50% by mass or less, further excellent permeability of the adhesive and sufficient Since the base material for double-sided adhesive tapes with a small paper thickness which has tensile strength is obtained, it is preferable.

  The double-sided pressure-sensitive adhesive tape substrate preferably contains only the core-sheath structure fiber and the unstretched single structure fiber as raw material fibers, but may contain other fibers as raw materials. In addition to polyester, for example, synthetic fibers such as rayon, polyvinyl alcohol, polyamide, polyolefin, and acrylic, and natural pulp fibers such as wood pulp can be used as the fiber. As content of fibers other than the said core-sheath structure fiber and unstretched single structure fiber, 10% or less is preferable, for example.

<Dispersant>
The base material for the double-sided pressure-sensitive adhesive tape is preferably added with a dispersant for the purpose of dispersing the fibers so that the pressure-sensitive adhesive or the like applied to the surface penetrates uniformly. As a dispersing agent mix | blended with the raw material (polyester fiber) which forms the said base material for double-sided adhesive tapes, the dispersing agent which has hydrophilic property and hydrophobicity is preferable. Such a dispersant is not particularly limited, and examples thereof include an anionic dispersant (anionic dispersant), a cationic dispersant (cationic dispersant), and an amphoteric dispersant (zwitter dispersion). Agent), nonionic dispersant (nonionic dispersant), and the like. Among these, a cationic dispersant is particularly preferable because of its excellent dispersibility with respect to polyester fibers.

  The blending amount of the dispersant is preferably 0.2 parts by mass or more and 0.8 parts by mass or less, and more preferably 0.3 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the polyester fiber. When the blending amount of the dispersant is less than 0.2 parts by mass, a sufficient dispersion effect may not be obtained. On the other hand, when the blending amount of the dispersant exceeds 0.8 parts by mass, the polyester fiber slurry tends to foam, and there is a risk of generating holes in the substrate during paper making.

<Antifoaming agent>
The anti-foaming agent is preferably added to the base material for double-sided pressure-sensitive adhesive tape for the purpose of preventing production problems such as paper breakage. As an antifoamer mix | blended with the raw material (polyester fiber) which forms the said base material for double-sided adhesive tapes, surfactant type | system | group and a silicone type antifoamer can be used, for example.

  0.4 mass part or more and 1.0 mass part or less are preferable with respect to 100 mass parts of polyester fibers, and, as for the compounding quantity of the said antifoamer, 0.5 mass part or more and 0.7 mass part or less are more preferable. When the blending amount of the antifoaming agent is less than 0.4 parts by mass, a sufficient defoaming effect cannot be obtained, the adhesive strength is lowered, and the base material may be easily cut. On the contrary, when the compounding quantity of an antifoamer exceeds 1.0 mass part, there exists a possibility that a formation may deteriorate.

  In addition to the said dispersing agent and antifoaming agent, various additives, such as a pigment and a filler, can be mix | blended with the said base material for double-sided adhesive tapes.

<Base material for double-sided adhesive tape>
The basis weight of the double-sided pressure-sensitive adhesive tape base material is preferably from 3 g / ^{m 2} or more 8 g / ^{m 2} or less, 4g / ^{m 2} or more 6 g / ^{m 2} or less is more preferable. If the basis weight of the base material for double-sided pressure-sensitive adhesive tape is less than 3 g / m ² , the tensile strength may not be sufficiently obtained and the sheet shape may not be maintained. On the contrary, when the basis weight of the double-sided adhesive tape substrate exceeds 8 g / m ² , the paper thickness becomes large, and the double-sided adhesive tape using the double-sided adhesive tape substrate is not suitable for thinning. There is a risk that it will not be suitable for fixing fine parts.

  The paper thickness of the base material for double-sided pressure-sensitive adhesive tape is from 15 μm to 40 μm, and more preferably from 20 μm to 30 μm. When the paper thickness of the base material for double-sided pressure-sensitive adhesive tape is less than 15 μm, the tensile strength is lowered and the paper is easily cut. On the contrary, when the paper thickness of the base material for double-sided pressure-sensitive adhesive tape exceeds 40 μm, paper thickness unevenness may occur, and the permeability of the pressure-sensitive adhesive decreases. Moreover, there exists a possibility that the double-sided adhesive tape using the said base material for double-sided adhesive tapes may become unsuitable for the fixation use of fine components, such as an electronic device. The paper thickness of the base material for double-sided pressure-sensitive adhesive tapes can be adjusted, for example, by changing the fiber type, fineness, fiber length, blending mass ratio, basis weight, and the like.

The density of the double-sided pressure-sensitive adhesive tape base material is preferably 0.10 g / cm ³ or more 0.25 g / cm ³ or less, 0.15 g / cm ³ or more 0.20 g / cm ³ or less is more preferable. If the density of the base material for double-sided pressure-sensitive adhesive tape is less than 0.10 g / cm ³ , the tensile strength may not be sufficiently obtained and the sheet shape may not be maintained. On the contrary, when the density of the base material for double-sided pressure-sensitive adhesive tape exceeds 0.25 g / cm ³ , the permeability of the pressure-sensitive adhesive deteriorates, and the adhesiveness of the double-sided pressure-sensitive adhesive tape using the base material for double-sided pressure-sensitive adhesive tape is sufficient. May not be obtained.

  The air permeability of the substrate for the double-sided pressure-sensitive adhesive tape is preferably 0.01 seconds / 300 ml · 100 sheets or more and 0.8 seconds / 300 ml · 100 sheets or less, 0.01 seconds / 300 ml · 100 sheets or more and 0.7 sheets or more. More preferably, the second / 300 ml · 100 sheets or less. When the air permeability of the double-sided adhesive tape substrate exceeds 0.8 seconds / 300 ml · 100 sheets, the permeability of the adhesive deteriorates, and the adhesiveness of the double-sided adhesive tape using the double-sided adhesive tape substrate May not be sufficiently obtained. On the other hand, in order to make the air permeability of the base material for double-sided pressure-sensitive adhesive tapes less than 0.01 sec / 300 ml · 100 sheets, it is necessary to remarkably reduce the basis weight, density, etc., which is difficult in production.

  The density and air permeability of the base material for the double-sided pressure-sensitive adhesive tape can be adjusted by changing, for example, the fiber type, fineness, fiber length, blending mass ratio, basis weight, and the like.

  The base material for the double-sided pressure-sensitive adhesive tape preferably has a tensile strength in the longitudinal direction of 67 N / m or more and 667 N / m or less, and more preferably 100 N / m or more and 300 N / m or less. If the tensile strength of the base material for double-sided pressure-sensitive adhesive tapes is less than 67 N / m, the base material for double-sided pressure-sensitive adhesive tapes is likely to break, and workability and handleability are reduced. Conversely, if the tensile strength of the double-sided pressure-sensitive adhesive tape substrate exceeds 667 N / m, the stretchability is lost and the followability to the adherend surface may be reduced. The tensile strength in the longitudinal direction of the base material for double-sided pressure-sensitive adhesive tape can be adjusted, for example, by changing the fineness, fiber length, blending mass ratio, basis weight, etc. of the fiber.

<Method for producing substrate for double-sided adhesive tape>
The base material for double-sided pressure-sensitive adhesive tape can be produced by paper making using the above-described polyester core-sheath structure fiber and unstretched single structure fiber as raw materials.

  Specifically, a base material for a double-sided pressure-sensitive adhesive tape is made using a raw material in which the core-sheath structure fiber and the unstretched single structure fiber are preferably blended with the dispersant, the antifoaming agent, and the like. The papermaking method is not particularly limited as long as it is a method used for ordinary papermaking. For example, a papermaking method using a circular net paper machine, a short net paper machine, a long net paper machine, an inclined short net paper machine, or the like. Can be used. Among these, when using a circular paper machine, the fibers are easily oriented in the flow direction, and the tensile strength in the machine direction of the resulting paper increases. Therefore, the tensile strength in the machine direction can be increased even if the basis weight is lowered. In addition, it is preferable because a uniform paper thickness can be obtained. In addition, as temperature of the dryer used by papermaking, 110 degreeC or more and 140 degrees C or less are preferable.

  In the production of the base material for the double-sided pressure-sensitive adhesive tape, it is preferable not to perform calendering. When calendering is performed, the density of the base material for double-sided pressure-sensitive adhesive tape increases, and the permeability may be reduced. On the contrary, by not performing the calendering process, the density of the base material for the double-sided pressure-sensitive adhesive tape can be reduced and the productivity can be improved.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

  In addition, each measured value in a present Example is a value measured with the following method.

[Fineness (unit: dtex)]
Measured according to JIS-L1095 (2010) “Test method for general spun yarn”.

[Fiber length (unit: mm)]
The number average fiber length was measured according to JIS-P8226 (2006) "Pulp-Fiber length measurement method by optical automatic analysis-Part 1: Polarization method".

[Basis weight (unit: g / m ² )]
Measured according to JIS-P8124 (1998) “Paper and paperboard—Measurement method of basis weight”.

[Paper thickness (unit: mm)]
Measured according to JIS-P8118 (1998) “Paper and paperboard—Test methods for thickness and density”.

[Density (unit: g / cm ³ )]
Measured according to JIS-P8118 (1998) “Paper and paperboard—Test methods for thickness and density”.

[Air permeability (unit: seconds / 300ml, 100 sheets)]
In accordance with JIS-P8117 (1998) “Paper and paperboard—Air permeability and air resistance test method (intermediate region) —Gurley test machine method”, 100-layer double-sided adhesive tape substrates were stacked with 300 ml of air The time (seconds) required to pass was measured.

[Tensile strength (unit: N / m)]
The tensile strength in the longitudinal direction was measured in accordance with JIS-P8113 (2006) “Paper and paperboard—Test method for tensile properties—Part 2: Constant speed extension method”.

  In this example, the following qualities were evaluated.

[Adhesive permeability]
An acrylic pressure-sensitive adhesive (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name: Coponel 5411) is applied to the film with a thickness of 100 μm, and a double-sided adhesive tape substrate is placed on the adhesive-coated surface of the film. Furthermore, a film not coated with an adhesive was placed on the surface opposite to the adhesive-coated film of the base material for the double-sided adhesive tape, and a test body was formed. The thickness of the test body after pinching this test body between glass plates and crimping | bonding by 50 kg / m < ² > was measured with the micrometer, and adhesive permeability was evaluated on the following references | standards.
(Evaluation criteria)
Penetration = [Test specimen thickness before pressurization (upper and lower two film thickness + substrate paper thickness + adhesive coating thickness)-test specimen thickness after pressurization] / substrate paper thickness x 100 (%)
○: Permeability is 40% or more.
Δ: Permeability is 20% or more and less than 40%.
X: Permeability is less than 20%.

[Example 1]
80% by mass of a core-sheath structure fiber (core-sheath polyester fiber, manufactured by Unitika Fiber Co., Ltd., core: melting point 255 ° C., sheath: melting point 110 ° C.) having a fineness of 1.7 dtex and a length of 5 mm, and a fineness of 0.00. The raw material which mix | blended 20 mass% of 2 dtex and unstretched single structure fiber (polyester fiber, the Teijin Fibers Ltd. make: softening point 125 degreeC) of length 3mm was prepared.

  A cationic dispersant (manufactured by Takemoto Yushi Co., Ltd.) as a dispersant is added to the raw material in an amount of 0.4 parts by mass with respect to 100 parts by mass of the polyester fiber, and a surfactant-based antifoaming agent (Hakuto Co., Ltd.) is used as the defoaming agent. 0.6 parts by mass was added to 100 parts by mass of polyester fiber.

The base material for double-sided adhesive tapes was manufactured with the circular net paper machine using the said raw material. In addition, the basic weight of the base material for double-sided adhesive tapes was 4.5 g / m < ² >, and the temperature of the dryer was about 120 degreeC. Moreover, thermal calendar processing is not implemented.

As a result of measuring the paper thickness, density, air permeability, and tensile strength in the longitudinal direction of the obtained double-sided adhesive tape substrate, the paper thickness was 25 μm, the density was 0.18 g / cm ³ , The degree was 0.5 sec / 300 ml · 100 sheets, and the tensile strength was 201 N / m.

[Examples 2 to 12 and Comparative Examples 1 to 6]
The fineness and content of the raw material core-sheath structure fibers and unstretched single structure fibers and the basis weight in Examples 2 to 12 and Comparative Examples 1 to 6 were as shown in Table 1. Moreover, the kind and addition amount of additives (dispersant and antifoaming agent) were the same as in Example 1.

  A base material for a double-sided pressure-sensitive adhesive tape was produced using the above raw materials in the same manner as in Example 1 using a circular net paper machine. Further, in the same manner as in Example 1, the paper thickness, density, air permeability, and tensile strength in the longitudinal direction of the obtained double-sided adhesive tape substrate were measured. Each measurement result is shown in Table 1. In addition, the base material for double-sided adhesive tapes of Comparative Example 3 was subjected to thermal calendering at a heating temperature of 200 ° C. after paper making.

[quality evaluation]
About each base material for double-sided adhesive tapes obtained in Examples 1-12 and Comparative Examples 1-6, the above-mentioned adhesive permeability was evaluated. The evaluation results are shown in Table 1.

  As shown from the results in Table 1, the base materials for double-sided pressure-sensitive adhesive tapes of Examples 1 to 12 exhibit excellent pressure-sensitive adhesive permeability while having a certain tensile strength. On the other hand, the base materials for double-sided pressure-sensitive adhesive tapes of Comparative Examples 1 to 3 do not exhibit sufficient pressure-sensitive adhesive permeability and are not suitable for actual use. Moreover, the base material for double-sided adhesive tapes of Comparative Examples 4 to 6 has a low tensile strength and is not suitable for actual use.

  As described above, the base material for double-sided pressure-sensitive adhesive tape of the present invention is excellent in the permeability of the pressure-sensitive adhesive and has a sufficient tensile strength even when having a low basis weight and a small paper thickness. Therefore, it can be suitably used as a substrate for a thin double-sided pressure-sensitive adhesive tape particularly used for fixing small electronic devices such as mobile phones and thin TV components.

Claims (3)

It is obtained by papermaking a raw material mainly composed of polyester core-sheath structure fiber and polyester unstretched single structure fiber,
Basis weight 3 g / ^{m 2} or more 8 g / ^{m 2} or less, the sheet thickness is Ri der least 40μm or less 15 [mu] m, density of the 0.1 g / cm ³ or more 0.25 g / cm ³ or less, air permeability 0. A base material for double-sided pressure-sensitive adhesive tapes having a tensile strength of 67 N / m or more and 8 seconds / 300 ml · 100 sheets or less .   The fineness of the core-sheath structure fiber is 1.1 dtex or more and 2.2 dtex or less, the fiber length is 3 mm or more and 10 mm or less, the fineness of the unstretched single structure fiber is 0.1 dtex or more and 1.2 dtex or less, and the fiber length is 1 mm. The base material for a double-sided pressure-sensitive adhesive tape according to claim 1, wherein the fineness of the core-sheath fiber is greater than the fineness of the unstretched single structure fiber.   The content rate of the said core-sheath structure fiber is 50 mass% or more and 90 mass% or less, and the content rate of the said unstretched single structure fiber is 10 mass% or more and 50 mass% or less. Base material for double-sided adhesive tape.