JP2014169420A - Double-sided adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester-based double-sided adhesive tape that uses only a small amount of organic solvent, is environmentally friendly, is excellent in economy and usability, and also is excellent in adhesive property, retention property and repulsion resistance, because it uses a polyester-based adhesive, without the use of an expensive silicone-based adhesive, a petroleum-based acrylic adhesive, or the like, and the molecular weight of the polyester used in a polyester-based adhesive is, in general, low as compared with the acrylic polymer used in an acrylic adhesive, and which allows the preparation of a coating liquid (adhesive solution) of high polymer concentration.SOLUTION: A double-sided adhesive tape formed of a polyester-based adhesive composition containing at least a polyester obtained by condensation polymerizing a dicarboxylic acid component and a diol component, and a tackifier, is characterized in that the gel fraction in the adhesive layer is 15 wt.% or more and less than 40 wt.%.

Description

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

  In recent years, OA equipment and electronic parts (particularly mobile equipment) such as mobile phones, digital cameras, PDAs, and digital video cameras have become more popular, and the number of production has increased. It is planned. For example, in a mobile phone, which is a representative device as a mobile device, each major component that is configured tends to be thinned in order to increase the display screen and improve portability.

  Usually, the display part is mainly composed of an LCD module and a backlight unit, and various sheet-like parts are used (laminated) in order to develop functions such as light emission, reflection, light shielding, and light guide. . In assembling (joining) these parts, a double-sided adhesive tape or the like is used (see Patent Document 1).

  As a raw material used for the double-sided adhesive tape, for example, a silicone-based pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive is used.

  However, in the case of a silicone-based pressure-sensitive adhesive, since it is expensive, it has a problem of poor economic efficiency.

  On the other hand, in the case of an acrylic adhesive, although it is low-cost, since petroleum is often used as its raw material, there is a possibility of a problem of depletion of petroleum resources. Moreover, since carbon dioxide is emitted by the disposal treatment after use, consideration for the global environment is not made and countermeasures for global warming are required.

  In addition, when preparing the acrylic pressure-sensitive adhesive, it is necessary to use many organic solvents, and then to heat and dry to remove the organic solvent, so that the workability is inferior and the environment is adversely affected. There is a risk. Furthermore, when an adhesive tape is produced using an acrylic adhesive solution containing a large amount of an organic solvent, it becomes difficult to form a thick adhesive layer, and the usage is limited due to the limitation of the thickness of the adhesive layer. Problem arises.

Japanese Patent Laid-Open No. 2002-249741

  Therefore, in view of the above circumstances, the present invention is a double-sided pressure-sensitive adhesive that uses a small amount of solvent, is friendly to the global environment, is excellent in economic efficiency and workability, and is excellent in adhesion, retention, and resilience resistance. The purpose is to provide a tape.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found the double-sided pressure-sensitive adhesive tape shown below and have completed the present invention.

  That is, the double-sided pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive layer formed from a polyester-based pressure-sensitive adhesive composition containing at least a polyester obtained by polycondensation of a dicarboxylic acid component and a diol component, and a tackifier. The gel fraction of the said adhesive layer is 15 weight% or more and less than 40 weight%, It is characterized by the above-mentioned.

  As for the double-sided adhesive tape of this invention, it is preferable that the adhesive force with respect to a SUS board is 6.5 N / 20mm or more.

  The double-sided pressure-sensitive adhesive tape of the present invention preferably has a holding power at 40 ° C. of 0.8 mm / 60 minutes or less.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the polyester preferably has a weight average molecular weight (Mw) of 5000 to 60000.

  In the double-sided pressure-sensitive adhesive tape of the present invention, the dicarboxylic acid component and the diol component are preferably composed mainly of plant-derived materials.

  In the double-sided pressure-sensitive adhesive tape of the present invention, it is preferable that the tackifier comprises a plant-derived raw material as a main component, and the softening point of the tackifier is 100 to 170 ° C.

  The double-sided pressure-sensitive adhesive tape of the present invention preferably has a release liner on at least one side of the pressure-sensitive adhesive layer.

  The double-sided pressure-sensitive adhesive tape of the present invention preferably has at least two pressure-sensitive adhesive layers and has a support on at least one side of the pressure-sensitive adhesive layer.

  Since the double-sided pressure-sensitive adhesive tape of the present invention uses a polyester-based pressure-sensitive adhesive, an acrylic used without an expensive silicone-based pressure-sensitive adhesive or a petroleum-based acrylic pressure-sensitive adhesive is used. Since the molecular weight of polyester used for polyester-based pressure-sensitive adhesives is usually smaller than that of polymer-based polymers, it is possible to prepare a coating solution (pressure-sensitive adhesive solution) with a high polymer concentration, and the amount of solvent used is low. A double-sided pressure-sensitive adhesive tape that is less in the global environment, excellent in economic efficiency and workability, and excellent in adhesion, retention, and repulsion resistance can be provided and is useful.

The state figure of the double-sided adhesive tape which stuck the release liner on both surfaces of the adhesive layer. The phase diagram of the double-sided adhesive tape which has an adhesive layer on both surfaces of a support body, and affixed the release liner on the surface of the adhesive layer.

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

<Double-sided adhesive tape>
The double-sided pressure-sensitive adhesive tape of the present invention (hereinafter sometimes simply referred to as double-sided pressure-sensitive adhesive tape or pressure-sensitive adhesive tape) includes at least a polyester obtained by polycondensation of a dicarboxylic acid component and a diol component, and a tackifier. If the gel fraction of the said adhesive layer is 15 weight% or more and less than 40 weight%, it will not be restrict | limited especially, It is a double-sided adhesive tape formed from the polyester-type adhesive composition containing these. However, for example, as an example of the double-sided pressure-sensitive adhesive tape, FIG. 1 includes one in which a release liner is pasted on both surfaces of the pressure-sensitive adhesive layer (no support). Further, FIG. 2 includes one having a pressure-sensitive adhesive layer on both surfaces of a support, and having a release liner attached to the surface of the pressure-sensitive adhesive layer (with a support). The pressure-sensitive adhesive layer may be a single pressure-sensitive adhesive layer (laminate) obtained by laminating two or more pressure-sensitive adhesive layers that are the same or different from each other, or a support. The double-sided pressure-sensitive adhesive tape may have two or more layers and three or more pressure-sensitive adhesive layers.

  By using the adhesive tape of the present invention, fossil resource depletion and carbon dioxide emission problems are suppressed without using expensive silicone adhesives or petroleum acrylic adhesives, and the use of solvents. It is possible to obtain a pressure-sensitive adhesive tape that is small in volume, is friendly to the global environment, is excellent in economic efficiency and workability, and is excellent in adhesiveness, retention, and resilience resistance. Polyester adhesives generally have excellent electrical insulation, mechanical strength, bending fatigue strength, water / chemical resistance, optical transparency, and almost no expansion and contraction. Since it can be made thick, it is suitable for various uses, particularly for insulation and fixing of electronic / electrical equipment.

<Polyester adhesive>
As polyester used for the adhesive tape, at least polyester obtained by polycondensation of a dicarboxylic acid component and a diol component is used. In addition, it does not specifically limit as a synthesis method of polyester, A well-known polymerization method can be used.

  Moreover, it is a preferable aspect that the said polyester is manufactured with the raw material derived from a plant. The reason is that the plant-derived raw material is said to be carbon neutral, which is friendly to the global environment and can provide an environmentally friendly pressure-sensitive adhesive.

  The polyester contains at least a dicarboxylic acid component, and the dicarboxylic acid component preferably has two carboxyl groups in the molecule, and the dicarboxylic acid component is mainly composed of a plant-derived raw material, This is a more preferred embodiment. Note that “plant-derived raw material as the main component” means that the so-called biomass degree is high, and “main component” means that the plant-derived raw material in the entire raw material is the highest proportion of the constituent raw materials. It means that there is.

Further, in the present invention, the biomass degree is a weight ratio of a plant-derived raw material used for producing the pressure-sensitive adhesive layer with respect to the total weight of the pressure-sensitive adhesive layer, and was calculated by the following calculation formula. Is.
Biomass degree of pressure-sensitive adhesive layer (% by weight) = 100 × [weight of plant-derived raw material (g)] / [total weight of pressure-sensitive adhesive layer (g)]

  The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer formed from a polyester-based pressure-sensitive adhesive composition containing at least a polyester obtained by polycondensation of a dicarboxylic acid component and a diol component, and a tackifier. An environmentally friendly pressure-sensitive adhesive can be obtained, which is a preferable embodiment.

  Examples of the dicarboxylic acid include, but are not particularly limited to, for example, plant-derived dicarboxylic acids such as castor oil-derived sebacic acid, oleic acid, dimer acid derived from erucic acid, and the like. Acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenyl succinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, Aliphatic and alicyclic dicarboxylic acids such as maleic acid, maleic anhydride, itaconic acid and citraconic acid, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, Examples thereof include 4'-diphenyl ether dicarboxylic acid. Among these, dimer acid and the like are particularly preferable from the viewpoint of being derived from plants and friendly to the global environment. These can be used alone or in combination of two or more.

  In addition to the dicarboxylic acid, a tricarboxylic acid containing three or more carboxyl groups can also be used. However, when a polyfunctional carboxylic acid such as tricarboxylic acid is used, a network structure (three-dimensional cross-linking structure) is formed, and the adhesive force (adhesive strength) of the adhesive layer (adhesive tape) is suppressed to a low level. When adhesiveness is required, it is preferable to refrain from use.

  The polyester preferably contains a diol component, and the diol component preferably contains at least two hydroxyl groups (hydroxyl groups) in the molecule. The diol component is mainly composed of plant-derived raw materials. It is a more preferable aspect to use as a component.

  Examples of the diol component include, but are not particularly limited to, for example, plant-derived diols such as fatty acid esters derived from castor oil, dimer diols derived from oleic acid, erucic acid, glycerol monostearate, and the like. Others include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl- 1,5-pentanediol, 2-ethyl-2-butylpropanediol As aliphatic glycols such as 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and the like other than the aliphatic glycol And ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polycarbonate glycol and the like. Among these, plant-derived aliphatic diols are particularly preferable from the viewpoint of being friendly to the global environment. These can be used alone or in combination of two or more.

  The molar ratio of the carboxylic acid component to the diol component is preferably 1: 1.04 to 2.10, more preferably 1: 1.06 to 1.70, and still more preferably 1: 1.07 to 1.30. When the molar ratio is less than 1: 1.04, the molecular weight of the resulting polyester increases, the number of hydroxyl groups that become functional groups decreases, and even if a crosslinking agent (for example, polyfunctional isocyanate) is used, a crosslinking reaction occurs. It is difficult to promote the pressure-sensitive adhesive, and it becomes impossible to obtain a pressure-sensitive adhesive layer having a desired gel fraction, and there is a fear that sufficient holding power (cohesive force) of the pressure-sensitive adhesive (layer) cannot be obtained. On the other hand, when the molar ratio exceeds 1: 2.10, there is a tendency that only a polyester having a molecular weight smaller than the desired molecular weight is obtained, and even if a cross-linking agent is used, gelation cannot be promoted. An adhesive layer having a gel fraction cannot be obtained, which is not preferable.

  Moreover, as polyester used for the adhesive tape (adhesive composition) of this invention, it is preferable that a weight average molecular weight (Mw) is 5000-60000, It is more preferable that it is 8000-50000, 15000-45000. More preferably. When the weight average molecular weight is less than 5000, the adhesive strength (adhesive strength) and holding power (cohesive strength) of the pressure-sensitive adhesive using the polyester may be reduced, and the adhesive tape ( The adhesive layer) itself may not be fixed. Moreover, when the weight average molecular weight exceeds 60,000, the hydroxyl group which becomes a functional group in the polyester decreases, and even if a cross-linking agent (polyfunctional isocyanate) is used, it becomes difficult to promote the cross-linking reaction. Since there exists a possibility that the adhesive layer which has a gel fraction may not be obtained, it is unpreferable. Since the polyester used in the present invention has a lower molecular weight than the acrylic polymer used in the acrylic adhesive, it is possible to prepare a coating solution (adhesive solution) with a high polymer concentration. Yes, it can form a thick adhesive layer and can be used for a wide range of applications.

  In addition, as long as the properties of the polyester used for the pressure-sensitive adhesive tape of the present invention are not impaired, other components other than the carboxylic acid component and the diol component can be polymerized or added after polymerization. It is.

  In the present invention, the polymerization (condensation polymerization) reaction between the carboxylic acid component and the diol component may be performed using a solvent or may be performed without a solvent, and conventionally known methods can be used.

  As a method for removing water generated by the polymerization (condensation polymerization) reaction, a method of azeotropic dehydration using toluene or xylene, an inert gas blown into the reaction system, and the generated water and And a method of discharging monoalcohol out of the reaction system, a method of distilling out under reduced pressure, and the like.

  As the polymerization catalyst used in the polymerization (condensation polymerization) reaction, those used for normal polyester polymerization catalysts can be used, and are not particularly limited. For example, titanium-based, tin-based, antimony, and the like. Various metal compounds such as those based on zinc, zinc and germanium, and strong acid compounds such as p-toluenesulfonic acid and sulfuric acid can be used.

<Crosslinking agent>
The pressure-sensitive adhesive tape (pressure-sensitive adhesive composition) of the present invention can contain a crosslinking agent. A pressure-sensitive adhesive layer can be formed by crosslinking reaction of the pressure-sensitive adhesive composition using a crosslinking agent. The crosslinking agent is not particularly limited, and conventionally known crosslinking agents can be used. For example, polyvalent isocyanurate, polyfunctional isocyanate, polyfunctional melamine compound, polyfunctional epoxy compound, polyfunctional A functional oxazoline compound, a polyfunctional aziridine compound, a metal chelate compound, and the like can be used. In particular, from the viewpoint of versatility, it is preferable to use a polyvalent isocyanurate or a polyfunctional isocyanate compound. These can be used alone or in combination of two or more.

  As said polyvalent isocyanurate, the polyisocyanurate body of hexamethylene diisocyanate etc. are mentioned, for example. By using these, it is possible to achieve the purpose of obtaining transparency and a high gel fraction of the obtained pressure-sensitive adhesive layer, which is effective. Commercially available products of the above polyvalent isocyanurates can also be used. Specifically, trade names “Duranate TPA-100” (manufactured by Asahi Kasei Chemicals), trade names “Coronate HK”, “Coronate HX”, “Coronate 2096” (Nippon Polyurethane Industry Co., Ltd.).

  The polyfunctional isocyanate compound is, for example, preferably a compound having at least 2 or more isocyanate groups in the molecule, more preferably 3 or more, and is not particularly limited. Aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates and the like can be mentioned.

  Examples of the aliphatic polyisocyanates include 1,2-ethylene diisocyanate, 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, tetramethylene diisocyanate such as 1,4-tetramethylene diisocyanate, Hexamethylene diisocyanates such as 2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexamethylene diisocyanate 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate and the like.

  Examples of the alicyclic polyisocyanates include isophorone diisocyanate, cyclohexyl diisocyanate such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate, 1,2-cyclopentyl diisocyanate, 1, Examples include cyclopentyl diisocyanate such as 3-cyclopentyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and the like.

  Examples of the aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and 2,2′-diphenylmethane diisocyanate. 4,4′-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4′-diisocyanate, 2,2′-diphenylpropane-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate 4,4′-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl- , 4'-diisocyanate, xylylene-1,4-diisocyanate, and the like xylylene-1,3-diisocyanate.

  In addition to the aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, dimers and trimers of araliphatic polyisocyanates may be used as the polyfunctional isocyanate compound. Specifically, diphenylmethane diisocyanate dimer or trimer, reaction product of trimethylolpropane and tolylene diisocyanate, reaction product of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, Polymers such as polyether polyisocyanate and polyester polyisocyanate are listed.

  Commercially available products can also be used as the polyfunctional isocyanate compound. Specifically, as a trimer adduct of trimethylolpropane and tolylene diisocyanate, the trade name “Coronate L” (manufactured by Nippon Polyurethane Industry Co., Ltd.) As a trimer adduct of trimethylolpropane and hexamethylene diisocyanate, trade name “Coronate HL” (manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like can be mentioned.

  Examples of the polyfunctional melamine compound include methylated methylol melamine and butylated hexamethylol melamine, and examples of the polyfunctional epoxy compound include diglycidyl aniline and glycerin diglycidyl ether.

  The type and amount of the crosslinking agent are not particularly limited, but the gel fraction of the formed pressure-sensitive adhesive layer is 15% by weight or more and less than 40% by weight, preferably 20 to 39% by weight, and more preferably. Is 25 to 39% by weight. If it is less than 15% by weight, sufficient holding power (cohesiveness) cannot be obtained, and if it exceeds 40% by weight, the crosslink density becomes high, and high adhesive force (adhesive strength) cannot be obtained. Since it is not suitable for a use, it is not preferable.

  In addition, as a compounding quantity of the said crosslinking agent, 0.5-30 weight part is preferable with respect to 100 weight part of said polyester, for example, More preferably, it is 1-20 weight part. When the blending amount is less than 0.5 parts by weight, when the pressure-sensitive adhesive layer is formed, the holding power (cohesive force) cannot be improved, and the heat resistance may be lowered. If it exceeds 1, the cross-linking reaction proceeds excessively and accompanied by a decrease in adhesive strength, which is not suitable for use as a double-sided pressure-sensitive adhesive tape.

  Moreover, in order to adjust efficiently the gel fraction of the adhesive layer used for the adhesive tape of this invention, a crosslinking catalyst can be used suitably. Examples of the catalyst include tetra-n-butyl titanate, tetraisopropyl titanate, butyl tin oxide, dioctyl tin diurarate, and the like. These can be used alone or in combination of two or more.

  The blending amount of the catalyst is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.5 part by weight with respect to 100 parts by weight of the polyester. If the blending amount is less than 0.01 parts by weight, the effect of catalyst addition may not be obtained, and if it exceeds 1 part by weight, the shelf life may be significantly shortened, and the coating stability may be reduced. It is not preferable.

  Moreover, in order to extend shelf life, it is also possible to mix | blend acetylacetone, methanol, ortho methyl acetate, etc. suitably as a retarder.

<Tackifier>
Moreover, the adhesive tape of this invention has an adhesive layer formed from the polyester-type adhesive composition containing a tackifier with the said polyester, and by containing the said tackifier, desired A pressure-sensitive adhesive layer having characteristics can be obtained, and in particular, improvement in adhesion (tackiness) and rebound resistance can be expected.

  The tackifier is not particularly limited, and conventionally known tackifiers can be used. However, it is more preferable to use a plant-derived raw material as a main component. For example, terpene tackifier, phenol tackifier, rosin tackifier, aliphatic petroleum resin, aromatic petroleum resin, copolymer petroleum resin, alicyclic petroleum resin, xylene resin, epoxy Examples include tackifiers, polyamide-based tackifiers, ketone-based tackifiers, and elastomer-based tackifiers. Rosin and terpene-based tackifiers that are produced from plant-derived materials to improve the degree of biomass. Is preferably used. These can be used alone or in combination of two or more.

  Examples of the terpene-based tackifier include terpene resins, terpene phenol resins, and aromatic modified terpene resins. Specifically, α-pinene polymers, β-pinene polymers, dipentene polymers, and the like A terpene resin modified with phenol, aromatic, hydrogenation, or hydrocarbon can be used.

  Specific examples of the phenol-based tackifier include condensates of various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, and formaldehyde. Furthermore, resole obtained by addition reaction of the phenols and formaldehyde under an alkali catalyst, novolak, unmodified or modified rosin obtained by condensation reaction of the phenols and formaldehyde under an acid catalyst, and these A rosin-modified phenol resin obtained by adding phenol to an rosin such as a derivative in the presence of an acid catalyst and subjecting it to thermal polymerization can be used.

  Examples of the rosin-based tackifier include rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenol resin, and the like. Specifically, gum rosin, wood rosin, tall oil An unmodified rosin such as rosin (raw rosin), a hydrogenated, disproportionated, polymerized, or other chemically modified modified rosin, or a derivative thereof can be used.

  As the tackifier, among others, the softening point measured by the ring and ball method is preferably 100 to 170 ° C, more preferably 110 to 165 ° C, and still more preferably 120 to 165 ° C. When the softening point is within the above range, it is preferable because both adhesiveness and repulsion resistance can be achieved.

  The blending amount of the tackifier is preferably 25 to 90 parts by weight, more preferably 30 to 88 parts by weight, and particularly preferably 35 to 86 parts by weight with respect to 100 parts by weight of the polyester. If the blending amount exceeds 90 parts by weight, the adhesiveness may be lowered, which is not preferable.

  As long as the properties of the pressure-sensitive adhesive layer (pressure-sensitive adhesive) used in the pressure-sensitive adhesive tape of the present invention are not impaired, silane coupling agents, surface lubricants, leveling agents, antioxidants, polymerization inhibitors, ultraviolet absorbers, light General stabilizers, release modifiers, plasticizers, softeners, inorganic or organic fillers, colorants such as pigments and dyes, anti-aging agents, surfactants, metal powders, particles, foils, etc. Additives can be used.

  Although it can select suitably as thickness (after drying) of the said adhesive layer, For example, about 1-150 micrometers is preferable, More preferably, it is about 3-100 micrometers, More preferably, it is about 5-60 micrometers. . When the thickness of the adhesive layer is less than 1 μm, it is difficult to obtain sufficient adhesive strength (adhesive strength), and the adhesive tape (adhesive layer) itself can be fixed to an adherend such as an electronic device or its parts. However, when the thickness exceeds 150 μm, the accuracy of the thickness is deteriorated at the time of coating, and unevenness is generated, which is not preferable. In addition, as an adhesive layer, any form of a single layer and a laminated body may be sufficient.

  Moreover, the double-sided pressure-sensitive adhesive tape of the present invention preferably has at least two layers of the pressure-sensitive adhesive layer, and has a support on at least one side of the pressure-sensitive adhesive layer. When the double-sided pressure-sensitive adhesive tape has a support on at least one surface of the pressure-sensitive adhesive layer, it is possible to improve mechanical strength, improve workability, and the like, which is a preferred embodiment.

<Support>
The support is not particularly limited, and conventionally known ones can be used, and various supports (substrates) such as plastic films, porous materials such as paper and nonwoven fabric can be used. . In addition, it is a preferable aspect to use a plastic film from viewpoints, such as durability. Examples of the plastic film include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, and ethylene / vinyl acetate copolymer. Polyolefin film such as coalescence, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer, polyester film such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyacrylate film, polystyrene film, nylon 6, Examples thereof include polyamide films such as nylon 6,6 and partially aromatic polyamide, polyvinyl chloride film, polyvinylidene chloride film, and polycarbonate film. Moreover, since the support body which consists of polylactic acid, a cellulose, etc. which are obtained from a plant-derived raw material can make the biomass degree of the whole double-sided adhesive tape high, it is used suitably.

  For the support, if necessary, various materials used for ordinary adhesive tape substrates (supports) such as ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, fillers, pigments and dyes. Additives can be used.

  If necessary, the surface of the support may be subjected to a conventional surface treatment in order to enhance the adhesion with the pressure-sensitive adhesive layer. For example, chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionization An oxidation treatment or the like by a chemical or physical method such as a radiation treatment may be performed, or a coating treatment or the like with a primer may be performed. Further, antifouling treatment with silica powder or the like, and antistatic treatment such as coating type, kneading type, and vapor deposition type can also be performed.

  Moreover, even if it has an intermediate | middle layer, undercoat, etc., if it is a range which does not impair the characteristic of the said support body used for the double-sided adhesive tape of this invention, it is satisfactory.

  The thickness of the support can be appropriately selected according to the material and form thereof, but is preferably 1000 μm or less, more preferably about 1 to 1000 μm, and particularly about 2 to 500 μm. Preferably, it is more preferably about 3 to 300 μm, and particularly preferably about 5 to 250 μm.

  As a method for forming the pressure-sensitive adhesive layer, a conventionally known method can be adopted. For example, a pressure-sensitive adhesive composition (a pressure-sensitive adhesive composition solution obtained by dissolving a pressure-sensitive adhesive composition in a solvent or a hot melt) is used. A method of forming a pressure-sensitive adhesive layer by applying and drying to the support, and a pressure-sensitive adhesive composition by applying and drying the pressure-sensitive adhesive composition to the support to form a pressure-sensitive adhesive composition layer and further crosslinking treatment. A method of forming an adhesive layer, a method of transferring (transferring) an adhesive layer coated / formed on a release liner, a method of extruding and applying an adhesive layer forming material onto a support, a support and It can be carried out based on a known method for producing a pressure-sensitive adhesive tape (pressure-sensitive adhesive sheet) such as a method of extruding a pressure-sensitive adhesive layer in two or multiple layers, a method of laminating a pressure-sensitive adhesive layer on a support, and the like. In addition to a support made of a thermoplastic resin, a method of co-extrusion molding of the pressure-sensitive adhesive layer by two layers or multiple layers by an inflation method or a T-die method can be used. In addition, the double-sided pressure-sensitive adhesive tape in the present invention includes a pressure-sensitive adhesive film, a pressure-sensitive adhesive sheet, and the like, and includes a double-sided pressure-sensitive adhesive tape without a support (adhesive layer alone) and a double-sided pressure-sensitive adhesive tape having a support.

  As a method of applying the pressure-sensitive adhesive composition (solution), a conventionally known method can be adopted. For example, roll coating, gravure coating, reverse roll coating, roll brush coating, air knife coating, spray coating, Examples include extrusion coating with a die coater.

  The pressure-sensitive adhesive layer of the present invention preferably has a release liner on at least one side. By having a release liner on one or both sides of the pressure-sensitive adhesive layer, the surface of the pressure-sensitive adhesive layer can be protected and stored until the time when the pressure-sensitive adhesive layer (adhesive tape / double-sided pressure-sensitive adhesive tape) is used. Is also useful.

<Release liner>
The release liner is not particularly limited, and conventionally known release liners can be used as appropriate. For example, in order to impart releasability to at least one surface of a substrate (release liner substrate), for example, coating with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent (release agent), etc. What formed the release coat layer to which the process was given can be used. Note that the release liner substrate may be in any form of a single layer or a plurality of layers.

  As the substrate for the release liner, various thin leaf bodies such as a plastic film, paper, foam, and metal foil can be used, and a plastic film is particularly preferable. Examples of the raw material for the plastic film include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene and ethylene-propylene copolymer, and thermoplastic resins such as polyvinyl chloride. In addition, a plastic film made of polylactic acid, polyester, polyamide or the like obtained from plant-derived raw materials can be suitably used.

  The thickness of the base material for release liner can be appropriately selected according to the purpose.

  The biomass degree of the entire double-sided pressure-sensitive adhesive tape of the present invention (including all components such as the pressure-sensitive adhesive layer, the support, and the release liner) is preferably 25% by weight or more, and more preferably 30% by weight. % Or more. When the degree of biomass is as high as 25% by weight or more as the whole double-sided pressure-sensitive adhesive tape, an environment-friendly double-sided pressure-sensitive adhesive tape can be obtained, which is a preferable embodiment. In addition, "biomass degree" here is derived from the plant used when manufacturing the said double-sided pressure-sensitive adhesive tape with respect to the total weight of the double-sided pressure-sensitive adhesive tape (weight of the entire raw material used such as pressure-sensitive adhesive layer and support). Means the weight percentage of the raw material calculated.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited to these examples. Further, “parts” in the examples means “parts by weight”. The contents of the adhesive layer (double-sided adhesive tape) and the evaluation results are shown in Table 1.

<Preparation of polyester A>
A three-necked separable flask was equipped with a stirrer, a thermometer, and a vacuum pump, to which dimer acid (trade name “Pripol 1009”, molecular weight 567, manufactured by Croda) 93.43 g, dimer diol (trade name “2033”, (Molecular weight 537, manufactured by Croda) 106.57 g, titanium tetraisopropoxide (manufactured by Kishida Chemical) 0.1 g as a catalyst was charged, and the temperature was raised to 200 ° C. while stirring in a reduced pressure atmosphere (2.0 kPa or less). The temperature was maintained. The reaction was continued for about 3 hours to obtain polyester A. The weight average molecular weight (Mw) was 20,000.
In addition, the usage-amount of said dimer acid and dimer diol was the ratio from which the hydroxyl group contained in dimer diol will be 1.20 mol with respect to 1.00 mol of carboxyl groups contained in dimer acid.

<Preparation of polyester B>
Polyester B was obtained in the same manner as Polyester A except that the amount of dimer acid used was changed to 97.33 g and the amount of dimer diol used was changed to 102.67 g. The weight average molecular weight (Mw) was 28,000.
In addition, the usage-amount of said dimer acid and dimer diol was the ratio from which the hydroxyl group contained in dimer diol will be 1.11 mol with respect to 1.00 mol of carboxyl groups contained in dimer acid.

<Example 1>
100 parts of polyester A, 5.80 parts of hexamethylene diisocyanate (trade name “TPA-100”, manufactured by Asahi Kasei Chemicals) as a crosslinking agent, rosin ester (trade name “Pencel D125”, manufactured by Arakawa Chemical Industries, Ltd.) as a tackifier ) 80 parts was blended, and toluene was added to adjust the pressure-sensitive adhesive so that the solid content was 70%. This was coated on the release-treated surface of a polyethylene terephthalate (PET) film (trade name “Diafoil MRF # 38”, manufactured by Mitsubishi Plastics Co., Ltd.) which was peel-treated so that the thickness after drying was 30 μm. It was made to dry for a while and the adhesive layer was obtained. Thereafter, the pressure-sensitive adhesive layer was bonded to the release-treated surface of a release-treated polyethylene terephthalate (PET) film (trade name “Diafoil MRE # 38”, manufactured by Mitsubishi Plastics), and left to stand at 40 ° C. for 3 days. I got a tape.

<Example 2>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the crosslinking agent was 3.25 parts and the tackifier was 40 parts with respect to 100 parts of polyester B.

<Example 3>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the tackifier was changed to rosin ester (trade name “Pencel D135”, manufactured by Arakawa Chemical Industries, Ltd.) and the crosslinking agent was changed to 6.25 parts.

<Example 4>
Adhesive tape in the same manner as in Example 1 except that 3.75 parts of the crosslinking agent was added to 100 parts of polyester B, and 40 parts of the rosin ester (trade name “Pencel D135”, manufactured by Arakawa Chemical Industries, Ltd.) was added as the tackifier. Got.

<Example 5>
An adhesive tape was obtained in the same manner as in Example 3 except that the crosslinking agent was changed to 6.50 parts.

<Example 6>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 5 except that the tackifier was rosin ester (trade name “Pencel D160”, manufactured by Arakawa Chemical Industries, Ltd.) and the cross-linking agent was changed to 6.75 parts.

<Example 7>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 2 except that the tackifier was changed to 40 parts of terpene resin (trade name “YS Resin PX1205”, manufactured by Yasuhara Chemical Co., Ltd.) and the crosslinking agent was changed to 2.30 parts.

<Example 8>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 7, except that 40 parts of the hydrogenated terpene resin (trade name “Clearon P135”, manufactured by Yasuhara Chemical Co., Ltd.) was used as the tackifier and the cross-linking agent was changed to 2.75 parts.

<Comparative Example 1>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the crosslinking agent was 3.80 parts and no tackifier was added.

<Comparative example 2>
An adhesive tape was obtained in the same manner as in Example 1 except that the crosslinking agent was 3.75 parts and the tackifier was 30 parts.

<Comparative Example 3>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that 2.80 parts of the crosslinking agent and no tackifier were added to 100 parts of polyester B.

<Comparative example 4>
A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that the crosslinking agent was changed to 3.00 parts and the tackifier was changed to 30 parts with respect to 100 parts of polyester B.

(Weight average molecular weight)
The weight average molecular weight (Mw) was measured from a calibration curve prepared by standard polystyrene using a gel permeation chromatography (GPC) method in which a polymer (polyester) was dissolved in tetrahydrofuran (THF).

(Measurement condition)
Device name: Tosoh Corporation, HLC-8220GPC
Test piece concentration: 0.1% by weight (THF solution)
Test piece injection volume: 20 μl
Eluent: THF
Flow rate: 0.300 ml / min
Measurement (column) temperature: 40 ° C
Column: Specimen column; TSKguardcolumn SuperHZ-L (1) + TSKgel SuperHZM-M (2), Reference column; TSKgel SuperH-RC (1), Tosoh detector: Differential refractometer (RI)

(Gel fraction of adhesive layer)
The pressure-sensitive adhesive composition (pressure-sensitive adhesive solution) was applied onto the release liner so that the thickness of the pressure-sensitive adhesive layers in Examples and Comparative Examples (the pressure-sensitive adhesive composition was dried and thickness after crosslinking) was 30 μm. An adhesive layer was prepared. Subsequently, the obtained pressure-sensitive adhesive layer was cut into a 5 cm × 5 cm square, the release liner was removed, and this was used as a test piece.
This test piece was wrapped in a Teflon (registered trademark) sheet whose weight was being measured, the weight was weighed, and left in toluene at 23 ° C. for 7 days to extract the sol content in the test piece. Then, it dried at 120 degreeC for 2 hours, and measured the weight after drying. The gel fraction was calculated by the following formula.
Gel fraction (% by weight) = 100 × (weight after drying−Teflon sheet weight) / (weight before drying−Teflon sheet weight)

  As a gel fraction of the said adhesive layer, it is 15 to 40 weight%, Preferably it is 20 to 39 weight%, More preferably, it is 25 to 39 weight%. If it is less than 15% by weight, the holding power (cohesiveness) cannot be obtained, and if it exceeds 40% by weight, the crosslinking density becomes high and high adhesive force (adhesive force) cannot be obtained, which is not preferable.

(Adhesion to SUS plate)
One peeled film was peeled from the obtained double-sided adhesive tape, and the exposed adhesive surface was bonded to a 25 μm thick polyethylene terephthalate (PET) film (trade name “Lumirror 25S10”, manufactured by Panac). A test piece was obtained. The test piece is cut into a width of 20 mm, the other peeled film is peeled off, and the exposed adhesive surface is bonded to a SUS304 plate to form a test piece, which has an adhesive strength to SUS plate (N / 20 mm). It was measured.
In addition, the pressure bonding at the time of bonding is performed by reciprocating a 2 kg roller once, and after 30 minutes of bonding, a 180 ° peel adhesive strength with a tensile and compression tester (device name “TG-1kN”, manufactured by Minebea Co., Ltd.). (Adhesive strength) was measured under the following conditions.
Tensile (peeling) speed: 300 mm / min Measurement conditions: Temperature: 23 ± 2 ° C., Humidity: 65 ± 5% RH

  The adhesive strength (adhesive strength) to the SUS plate is preferably 6.5 N / 20 mm or more, more preferably 6.8 N / 20 mm or more, and further preferably 7 N / 20 mm or more. If the adhesive strength is less than 6.5 N / 20 mm, the adhesive strength becomes too low and the tape may be peeled off, which is not preferable.

(Holding power)
One peeled film was peeled from the obtained double-sided adhesive tape, and the exposed adhesive surface was bonded to a 25 μm thick polyethylene terephthalate (PET) film (trade name “Lumirror 25S10”, manufactured by Panac). A test piece was obtained. The test piece was cut into a width of 10 mm × length of 100 mm, the other peeled film was peeled off, and the exposed adhesive surface was applied to a bakelite plate having a width of 25 mm × length of 125 mm × thickness of 2 mm in the width direction and The length direction was made to correspond to each other, and a measurement piece was obtained by reciprocating and bonding with a 2 kg roller so as to wrap around a central portion in the width direction of the bakelite plate 10 mm wide × 20 mm long. Using this measurement piece, after leaving it to stand in an atmosphere of 40 ° C. for 30 minutes, the deviation length of the test piece after being left in an atmosphere of 40 ° C. for 1 hour (60 minutes) with a load of 0.5 kg applied ( mm / 60 minutes).

  The holding force at 40 ° C. is preferably 0.8 mm / 60 minutes or less, more preferably 0.5 mm / 60 minutes or less, and still more preferably 0.4 mm / 60 minutes or less. When the holding force exceeds 0.8 mm / 60 minutes, the displacement increases, and it is not preferable because it cannot be fixed for a long time.

(Rebound resistance)
The obtained adhesive tape was cut into a width of 10 mm and a length of 90 mm, and one of the peeled films was peeled off and the exposed adhesive surface was bonded to an aluminum plate having a width of 10 mm, a length of 90 mm, and a thickness of 0.3 mm. A test piece was prepared and allowed to stand at room temperature for 24 hours.
The longitudinal direction (length direction) of the test piece was bent along a round bar having a diameter (φ) of 30 mm, and bent in an arc shape so that the aluminum plate side was inside. Next, the other peeled film of the test piece is peeled to expose the adhesive surface, and one end (adhesive surface side) in the length direction of the test piece is temporarily bonded to the adherend (polycarbonate plate). Furthermore, this was press-bonded using a roll laminator (crimping conditions: 23 ° C., 0.3 m / min). After standing at room temperature for 24 hours, the height (mm) of the end of the test piece lifted from the surface of the adherend was measured, and the average value of the raised height of both ends of the test piece (N = 2). Was evaluated as “floating height” (mm). In calculating the average value, it is preferable to use as many test pieces as possible.

  The smaller the “floating height”, the better the resilience resistance (resilience resistance), and preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. is there. When the “floating height” exceeds 10 mm, peeling occurs, and it cannot be fixed for a long time, which is not preferable.

注）表１中のＧは、凝集破壊を起こし、正確な値が得られなかったことを意味する。

Note) G in Table 1 means that cohesive failure occurred and an accurate value was not obtained.

  From the evaluation results in Table 1, it was confirmed that in Examples 1 to 8, a double-sided pressure-sensitive adhesive tape having desired adhesiveness, retention and repulsion resistance can be obtained.

  On the other hand, in Comparative Examples 1 and 3, since no tackifier was used, interfacial adhesion was not obtained, the floating height was less likely to occur, and the rebound resistance was poor. In Comparative Examples 2 and 4, Since the gel fraction of the pressure-sensitive adhesive layer was very low, it caused cohesive failure, the adhesive strength could not be evaluated, and the retention was also very poor, the sample itself dropped and the floating height In addition, it showed a very large numerical value, poor repulsion resistance, and was inferior to the evaluation of the examples.

DESCRIPTION OF SYMBOLS 1 Release liner 2 Adhesive layer 3 Support body 10 Double-sided adhesive tape (no support body)
10 'double-sided adhesive tape (with support)

Claims (8)

At least a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed from a polyester-based pressure-sensitive adhesive composition containing a polyester obtained by polycondensation of a dicarboxylic acid component and a diol component, and a tackifier,
The double-sided pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer has a gel fraction of 15% by weight or more and less than 40% by weight.   The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the adhesive strength to the SUS plate is 6.5 N / 20 mm or more.   The double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein a holding force at 40 ° C is 0.8 mm / 60 minutes or less.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein the polyester has a weight average molecular weight (Mw) of 5000 to 60000.   The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the dicarboxylic acid component and the diol component contain a plant-derived raw material as a main component. The tackifier is mainly composed of plant-derived raw materials,
The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein a softening point of the tackifier is 100 to 170 ° C.   The double-sided pressure-sensitive adhesive tape according to claim 1, further comprising a release liner on at least one surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer has at least two layers,
The double-sided pressure-sensitive adhesive tape according to claim 1, further comprising a support on at least one surface of the pressure-sensitive adhesive layer.

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