JP7211537B2 - Adhesive tape - Google Patents

Description

The present invention relates to adhesive tapes.

Adhesive tapes are used, for example, for fixing parts and members constituting mobile electronic terminals, cameras, personal computers, home appliances, automobiles, and the like.

Examples of raw materials used for such adhesive tapes for fixing members include silicone-based adhesives and acrylic-based adhesives. However, in the case of a silicone-based pressure-sensitive adhesive, the cost is high, so it is not economically viable. On the other hand, acrylic pressure-sensitive adhesives are low-cost, but they often use petroleum as a raw material, so there are problems of depletion of petroleum resources and carbon dioxide emissions due to disposal.

In recent years, as interest in environmental problems such as global warming has increased, there has been a strong social demand to use plant-derived raw materials as substitutes for conventional petroleum-derived raw materials.

However, it is difficult to satisfy the conventionally required performance using plant-derived raw materials, and tapes with a particularly high degree of biomass have a drawback of poor adhesiveness.

Therefore, it is a polyester adhesive tape with a high biomass content using plant-derived raw materials, and the biomass content, gel fraction, molar ratio between the carboxylic acid component and the diol component, and the adhesive strength to the polycarbonate plate are specified. has been proposed (see, for example, Patent Document 1).

Japanese Patent No. 6343463

In recent years, there has been a demand to recycle and reuse used products from the viewpoint of protecting the global environment. When recycling and reusing, it is necessary to peel off the adhesive tape used to fix the parts.In addition to the adhesive strength, the adhesive tape has excellent performance (removability) that can be peeled off cleanly during reuse and recycling. is requested to provide.

However, although the pressure-sensitive adhesive tape described in Patent Document 1 exhibits a relatively high adhesive strength, it cannot be said to have sufficient removability.

Accordingly, an object of the present invention is to provide an adhesive tape that has a high degree of biomass content, sufficient adhesive strength, and excellent removability.

As a result of extensive research to solve the above problems, the present inventors have found that adhesive tapes exhibiting a high gel fraction and a high degree of biomass (for example, 80% by weight or more) exhibit high adhesive strength and excellent reusability. The present inventors have found that it exhibits releasability and have completed the present invention.

That is, the present invention includes the following aspects.
[1] It has a pressure-sensitive adhesive layer containing a polyester-based resin, the pressure-sensitive adhesive layer has a biomass degree of 80% by weight or more, and the pressure-sensitive adhesive layer has a gel fraction of 40% by weight or more. An adhesive tape characterized by having an adhesive force of 4 to 14 N/20 mm.
[2] The pressure-sensitive adhesive tape according to [1] above, wherein the pressure-sensitive adhesive layer has a gel fraction of 40% by weight to 85% by weight.
[3] The pressure-sensitive adhesive tape according to [1] or [2], wherein the polyester resin has a weight average molecular weight (Mw) of 50,000 to 150,000.
[4] Any one of the above [1] to [3], wherein the adhesive layer has interfacial peelability even after being left for 500 hours in a high temperature and high humidity environment of 60 ° C. and 90%. The adhesive tape described in .
[5] The pressure-sensitive adhesive tape according to any one of [1] to [4], which has a release liner on at least one side of the pressure-sensitive adhesive layer.

INDUSTRIAL APPLICABILITY The present invention can provide a pressure-sensitive adhesive tape having a high degree of biomass, sufficient adhesive strength, and excellent removability.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of a structure of the adhesive tape of this invention. FIG. 3 is a schematic diagram showing another example of the configuration of the pressure-sensitive adhesive tape of the present invention;

The adhesive tape of the present invention will be described in detail below, but the description of the constituent elements described below is an example as one embodiment of the present invention, and is not limited to these contents.
(Adhesive tape)

The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer containing a polyester-based resin. The biomass degree of the pressure-sensitive adhesive layer is 80% by weight or more. The gel fraction of the adhesive layer is 40% by weight or more. The adhesive layer has an adhesive strength to a stainless steel plate of 4 to 14 N/20 mm.
<Adhesive layer>

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is composed of a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition can contain a cross-linking agent and a tackifier in addition to the polyester resin. Moreover, the adhesive composition may further have other components.
<<polyester resin>>

The adhesive composition according to the present invention contains a polyester-based resin. As the polyester-based resin, it is preferable to use at least a polyester obtained by polycondensation of a carboxylic acid component and a diol component. A method for synthesizing the polyester is not particularly limited, and a known polymerization method can be used.

Polyester is preferably produced from plant-derived raw materials. The reason for this is that the plant-derived raw material is said to be carbon-neutral, and an environment-friendly pressure-sensitive adhesive can be obtained that is friendly to the global environment.

The polyester contains a carboxylic acid component, and the carboxylic acid component preferably contains at least a dicarboxylic acid containing two carboxyl groups.

Dicarboxylic acids include sebacic acid, azelaic acid, isophthalic acid and the like. Dicarboxylic acids can be used singly or in combination of two or more. Among them, sebacic acid and azelaic acid are particularly preferable from the viewpoint of being derived from plants and being friendly to the global environment.

Others include adipic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, and tetrahydrophthalic anhydride. acids, aliphatic and alicyclic dicarboxylic acids such as maleic acid, maleic anhydride, itaconic acid and citraconic acid, terephthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4 ,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid and the like.

The polyester preferably contains a diol component, and the diol component preferably contains at least two hydroxyl groups in the molecule.

Diol components 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, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, etc. Aliphatic glycols and those other than the above aliphatic glycols, ethylene oxide adducts and propylene oxide adducts of bisphenol A, ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A, polytetramethylene glycol, polypropylene glycol, polyethylene glycol, polycarbonate glycol and the like. A diol component can be used 1 type or in combination of 2 or more types. For example, diethylene glycol and ethylene glycol can be used in combination.
<<Weight Average Molecular Weight (Mw) of Polyester Resin>>

The weight average molecular weight (Mw) of the polyester resin according to the present invention is preferably 50,000 or more, more preferably 55,000 or more, more preferably 60,000 or more, more preferably 80,000 or more, and still more preferably 100,000 or more. Moreover, the weight average molecular weight (Mw) is preferably 150,000 or less, and more preferably 140,000 or less. Specifically, the range of the weight average molecular weight (Mw) is preferably from 50,000 to 150,000, more preferably from 55,000 to 150,000, and particularly preferably from 100,000 to 150,000. is preferably in the range of If the weight-average molecular weight is 60,000 or more, preferable removability is exhibited by having a desired gel fraction. Further, when the weight average molecular weight is 100,000 or more, the cohesive force is high due to the high molecular weight, and the retention property is high. On the other hand, from the viewpoint of ease of synthesis, the weight average molecular weight is preferably 150,000 or less.

The weight average molecular weight (Mw) can be measured from a calibration curve prepared with standard polystyrene by using a gel permeation chromatography (GPC) method for a solution of the polymer dissolved in tetrahydrofuran (THF). .
<<Conditions for measurement of weight average molecular weight of polyester resin>>

Apparatus name: HLC-8420GPC manufactured by Tosoh Corporation
Concentration: 4 mg/mL (THF solution)
Injection volume: 100 μL Solvent: THF
Flow rate: 1.0 mL/min
Measurement (column) temperature: 40°C
Column: TSKgel G5000/G4000/G3000/G2000-HxL
Detector: RI, UV

In order to ensure the desired adhesiveness of the polyester-based resin, it is preferable to consider the number of equivalents of the dicarboxylic acid and the diol component. For example, the mixing ratio of the dicarboxylic acid component and the diol component is preferably in the range of 1 to 2 equivalents of the diol component per equivalent of the dicarboxylic acid, and more preferably in the range of 1.1 to 1.7 equivalents. .

It should be noted that components other than the carboxylic acid component and the diol component can be polymerized or added after the polymerization as long as the properties of the polyester used for the adhesive tape are not impaired.

For the polymerization (condensation polymerization) reaction between the carboxylic acid component and the diol component, conventionally known methods such as solvent-based and non-solvent-based methods can be used. A solventless system is particularly preferred from the viewpoint of environmental protection.

As a method for removing water generated in the polymerization (condensation polymerization) reaction, there is a method of azeotropic dehydration using toluene or xylene, or a method of blowing an inert gas into the reaction system to remove the generated water, Examples include a method of discharging the monoalcohol out of the reaction system, a method of distilling under reduced pressure, and the like.

As the polymerization catalyst used in the polymerization (condensation polymerization) reaction, those used in ordinary polyester polymerization catalysts can be used, and are not particularly limited. Examples include germanium, titanium, and tin catalysts. , antimony-based, and zinc-based metal compounds can be used. These may be used singly or in combination of two or more. Germanium dioxide is preferably used because of its high catalytic activity.
<<crosslinking agent>>

The pressure-sensitive adhesive composition for the pressure-sensitive adhesive tape of the present invention may contain a cross-linking agent. A pressure-sensitive adhesive layer can be formed by cross-linking the polyester-based resin using a cross-linking agent. The type of cross-linking agent is not particularly limited as long as the effect of the present invention is exhibited, and can be appropriately selected according to the purpose. An isocyanate-based cross-linking agent is more preferred.

The polyfunctional isocyanate compound is, for example, preferably a compound having at least 2 or more isocyanate groups in the molecule, and more preferably 3 or more, and is not particularly limited. group polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like. A crosslinking agent can be used 1 type or in combination of 2 or more types.

Examples of aliphatic polyisocyanates include 1,2-ethylene diisocyanate, tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,2 - hexamethylene diisocyanates such as 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 alicyclic polyisocyanates include isophorone diisocyanate, cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate and 1,4-cyclohexyl diisocyanate, 1,2-cyclopentyl diisocyanate, 1,3 -cyclopentyl diisocyanate such as cyclopentyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and the like.

Examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 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-4,4'-diisocyanate, xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate and the like.

Further, as the polyfunctional isocyanate compound, in addition to aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, dimers and trimers of araliphatic polyisocyanates can be used, Specifically, dimers and trimers of diphenylmethane diisocyanate, reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, polyether Examples thereof include polymers such as polyisocyanate and polyester polyisocyanate. Preferably, an adduct of tolylene diisocyanate and trimethylolpropane can be used.

As the polyfunctional isocyanate compound, a commercially available product can also be used. Specifically, as a trimer adduct of trimethylolpropane and tolylene diisocyanate, the trade name "Barnock D-40" (manufactured by DIC Corporation). and as a trimer adduct of trimethylolpropane and hexamethylene diisocyanate, trade name "Coronate HL" (manufactured by Nippon Polyurethane Industry Co., Ltd.).

For example, when the cross-linking agent is an isocyanate compound, the amount of the cross-linking agent is 1.4 to 5.0 parts by weight with respect to 100 parts by weight of the polyester resin that is the main component of the adhesive. preferable. Among them, the range of 1.4 to 4.0 parts by weight, the range of 1.4 to 3.0 parts by weight, and the range of 1.4 to 2.0 parts by weight are more preferable. When the amount of the cross-linking agent is 1.4 parts by weight or more with respect to 100 parts by weight of the polyester resin, the desired gel fraction (for example, 40% by weight or more) is obtained, and good removability can be obtained. . If the blending amount is 5.0 parts by weight or less, the pressure-sensitive adhesive can exhibit desired adhesive strength.

As the type of cross-linking agent, in addition to the above isocyanate compounds, polyvalent isocyanurates, polyfunctional melamine compounds, polyfunctional epoxy compounds, polyfunctional oxazoline compounds, polyfunctional aziridine compounds, metal chelate compounds, and the like can also be used. can.
<<Tackifier>>

In order to form the pressure-sensitive adhesive layer used in the pressure-sensitive adhesive tape of the present invention, a pressure-sensitive adhesive layer having desired properties is obtained by combining a polyester resin, which is the main component of the pressure-sensitive adhesive, with a cross-linking agent and a tackifier. In particular, improvement in adhesiveness (adhesiveness) can be expected.

The tackifier is not particularly limited, and conventionally known tackifiers can be used. , aromatic petroleum resins, copolymer petroleum resins, alicyclic petroleum resins, xylene resins, epoxy tackifiers, polyamide tackifiers, ketone tackifiers, elastomer tackifiers, etc. In particular, in order to maintain and improve the degree of biomass, it is preferable to use a rosin-based or terpene-based tackifier produced from plant-derived raw materials. These can be used singly or in combination of two or more.

Examples of rosin-based tackifiers include unmodified rosins (fresh rosins) such as gum rosin, wood rosin, tall oil rosin, and modified rosins obtained by modifying these unmodified rosins by polymerization, disproportionation, hydrogenation, etc. polymerized rosin, stabilized rosin, disproportionated rosin, completely hydrogenated rosin, partially hydrogenated rosin, and other chemically modified rosins), and various rosin derivatives. Examples of the above-mentioned rosin derivatives include rosin phenolic resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and subjecting them to thermal polymerization; Ester compound (unmodified rosin ester) of rosin esterified with alcohol, and modified rosin obtained by esterifying modified rosin such as polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, and partially hydrogenated rosin with alcohol rosin ester resins such as ester compounds (polymerized rosin ester, stabilized rosin ester, disproportionated rosin ester, fully hydrogenated rosin ester, partially hydrogenated rosin ester, etc.); unmodified rosin and modified rosin (polymerized rosin, stabilized Unsaturated fatty acid-modified rosin resin obtained by modifying rosin with unsaturated fatty acid; Unsaturated fatty acid-modified rosin obtained by modifying rosin ester resin with unsaturated fatty acid Ester-based resin; unmodified rosin, modified rosin (polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin, etc.), unsaturated fatty acid modified rosin resin, unsaturated fatty acid modified rosin ester type Rosin alcohol-based resins obtained by reducing carboxyl groups in resins; metal salts of rosin-based resins such as unmodified rosin, modified rosin, and various rosin derivatives (especially rosin ester-based resins);

Terpene-based tackifiers include, for example, terpene-based resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer, and modifications of these terpene-based resins (phenol modification, aromatic modification, hydrogenation modification modified terpene-based resins (for example, terpene-phenolic resins, styrene-modified terpene-based resins, aromatic modified terpene-based resins, hydrogenated terpene-based resins, etc.).

The tackifier preferably has a softening point of 100 to 170°C, more preferably 100 to 165°C, even more preferably 100 to 135°C.

Better removability is obtained when the tackifier is not contained or contained in a small amount. However, the adhesive strength may be weakened. On the other hand, when the content of the tackifier is large, the adhesive strength is high, but the removability may be deteriorated. Therefore, in the present invention, it is preferable to select the type and blending amount of the tackifier in consideration of both adhesive strength and removability. For example, the blending amount of the tackifier is preferably 0 to 15 parts by weight with respect to 100 parts by weight of the polyester resin that is the main component of the adhesive.
<<hydrolysis inhibitor>>

The pressure-sensitive adhesive layer used in the pressure-sensitive adhesive tape of the present invention may contain a hydrolysis inhibitor, and by containing the hydrolysis inhibitor, the durability is improved particularly under high temperature and high humidity, resulting in good removability. sex can be expected.

The hydrolysis inhibitor is not particularly limited, and conventionally known ones can be used. Examples include compounds having functional groups such as carbodiimide groups, epoxy groups, oxazoline groups, and the like. Among these, carbodiimide group-containing compounds are preferred because they are highly effective in eliminating the catalytic activity of protons derived from carboxyl terminal groups.

Carbodiimide group-containing compounds include, for example, Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Co., Ltd. Among them, Carbodilite (registered trademark) V-03, V-05, V-07 and V-09 are It is preferable in terms of excellent compatibility with organic solvents.
<<Other Ingredients>>

In order to efficiently adjust the gel fraction of the pressure-sensitive adhesive layer used in the pressure-sensitive adhesive tape of the present invention, a cross-linking catalyst may be used as appropriate. Examples of catalysts include tetra-n-butyl titanate, tetraisopropyl titanate, butyltin oxide, dioctyltin diuralate, titanium acetoacetate, zirconium tetraacetylacetonate and the like. These can be used singly or in combination of two or more.

The amount of the cross-linking catalyst is not particularly limited, but is preferably 0.01 to 1 part by weight with respect to 100 parts by weight of the polyester-based resin, which is the main component of the adhesive. When the amount is 0.01 part by weight or more, the effect of adding the catalyst can be obtained.

Moreover, in order to prolong the pot life, a retarder such as acetylacetone, methanol, or methyl orthoacetate may be blended as appropriate.

As long as it does not impair the properties of the adhesive layer (adhesive) used in the adhesive tape of the present invention, silane coupling agents, surface lubricants, leveling agents, antioxidants, polymerization inhibitors, ultraviolet absorbers, light Stabilizers, release modifiers, plasticizers, softeners, inorganic or organic fillers, colorants such as pigments and dyes, anti-aging agents, surfactants, metal powders, particulates, foils, and other general Additives can be used.
<Method for Forming Adhesive Layer>

As a method for producing the pressure-sensitive adhesive tape of the present invention, for example, in the case of a pressure-sensitive adhesive tape having a base material (core), the pressure-sensitive adhesive composition is applied to one or both sides of the base material, followed by drying or the like. method (direct method), or after forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to the surface of a release liner and drying, etc., the pressure-sensitive adhesive layer is transferred to one or both sides of the substrate. A manufacturing method (transfer method) can be mentioned.

Moreover, as a method for producing a substrate-less pressure-sensitive adhesive tape, for example, there is a method of forming a pressure-sensitive adhesive layer by coating a pressure-sensitive adhesive composition on the surface of a release liner and drying the composition.

Examples of the method of applying the pressure-sensitive adhesive composition to the substrate or release liner include methods using an applicator, roll coater, gravure coater, reverse coater, spray coater, air knife coater, die coater, and the like.

A method for drying the adhesive composition includes, for example, a method of drying at 50° C. to 140° C. for 30 seconds to 10 minutes. Further, after drying, aging may be further carried out in the range of 30° C. to 50° C. in order to accelerate the curing reaction.
<<Biomass degree>>

The biomass degree of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is preferably 80% by weight or more, more preferably 90% by weight or more. A high biomass content of 80% by weight or more makes it possible to obtain an environmentally friendly pressure-sensitive adhesive tape that is friendly to the global environment, which is a preferred embodiment.

The degree of biomass is the weight ratio of the plant-derived raw material used when producing the pressure-sensitive adhesive layer to the total weight of the pressure-sensitive adhesive layer, and is calculated using the following formula.
Biomass degree of adhesive layer (% by weight) = 100 × [weight of plant-derived raw material (g)] / [total weight of adhesive layer (g)]
<<Gel Fraction>>

The gel fraction is 40% by weight or more to ensure good removability. Furthermore, the gel fraction of the pressure-sensitive adhesive layer is preferably in the range of 40% by weight to 85% by weight in order to ensure excellent adhesive strength while ensuring removability. Moreover, in the present invention, it is preferable to adjust various conditions such as the molecular weight of the polyester, the type and content of the cross-linking agent, and the type and content of the tackifier so that the gel fraction falls within the desired range.

When the gel fraction is 40% by weight or more, good removability can be obtained. Also, when the gel fraction is about 85% by weight or less, good adhesive properties are obtained. Among them, the gel fraction of the pressure-sensitive adhesive layer is more preferably in the range of 45% by weight to 60% by weight, since the balance between adhesive properties and removability is improved.
<<Method for measuring gel fraction>>

The gel fraction is measured as follows. On the release sheet, the adhesive is applied so that the thickness after drying is 50 μm, dried at 100 ° C. for 3 minutes, aged at 40 ° C. for 4 days, cut into 50 mm squares, and used as samples. . Next, the weight (G1) of the sample before immersion in toluene is measured in advance, and the toluene-insoluble portion of the sample after immersion in the toluene solution at 23 ° C. for 24 hours is separated by filtration through a 300-mesh wire mesh. Then, after drying at 110° C. for 1 hour, the weight of the residue (G2) is measured, and the gel fraction is obtained according to the following formula.
Gel fraction (% by weight) = (G2/G1) x 100
<<adhesion>>

The adhesive strength can be evaluated based on the adhesive strength to a stainless steel plate. The adhesive force to a stainless steel plate is preferably in the range of 4 to 14N/20mm. When the adhesive strength is 4 N/20 mm or more, a desired adhesive strength can be obtained, which is suitable for fixing members of electronic devices and the like.
<<Method for measuring adhesion force to stainless steel (SUS) plate>>

A surface having an adhesive part of a 20 mm wide adhesive tape (hereinafter referred to as a test piece) lined with a polyethylene terephthalate film having a thickness of 25 μm and a clean and smooth stainless steel plate are overlapped, and the upper surface is rolled with a 2 kg roller. The pressure was applied by reciprocating the tape one time and left for 1 hour under the conditions of 23 ° C. and 50% RH according to JISZ-0237. It was measured by peeling off at a speed of 0.3 m/min in the ° direction.
<<Removability>>

Removability is evaluated by whether or not interfacial peeling occurs when the above test piece left under predetermined environmental conditions is peeled off. Regarding Examples 1 to 9 and Comparative Examples 1 to 3, which will be described later, a test piece prepared in a test of adhesive strength to a stainless steel (SUS) plate was attached to a stainless steel plate, and was placed in an environment of 60 degrees Celsius and 90% humidity for 500 hours. After the test piece is left to stand, when the test piece is peeled off from the stainless steel plate, it can be evaluated by whether or not interfacial peeling occurs in the test piece.

As a further test, with respect to Examples 10 to 15 described later, a test piece prepared in a test of adhesive strength to a stainless steel (SUS) plate was attached to a stainless steel plate and placed in an environment of 85 ° C. (without humidity adjustment) for 500 hours. When the test piece is peeled off from the stainless steel plate after being left to stand, it can be evaluated whether or not interfacial peeling occurs in the test piece.

In addition, when the adhesive layer has interfacial releasability, it means that when the adhesive tape is peeled off from the adherend, it does not separate between or within the layers of the adhesive tape, and adhesive remains on the adherend surface at the interface with the adherend. It means to peel off without peeling.
<Structure of Adhesive Tape>

The pressure-sensitive adhesive tape of the present invention is not particularly limited as long as it has a pressure-sensitive adhesive layer with a biomass content of 80% by weight or more. For example, FIG. 1 shows an example of an adhesive tape in which a release liner is attached to one side of an adhesive layer (no base material). Note that the release liner may be attached to both sides of the pressure-sensitive adhesive layer.

In addition, FIG. 2 includes a substrate having an adhesive layer on one side and a release liner attached to the surface of the adhesive layer (with substrate). As the adhesive layer, two or more adhesive layers made of the same or different raw materials may be laminated to form a single adhesive layer (laminate), or the base material may be The pressure-sensitive adhesive tape may have two or more layers and three or more pressure-sensitive adhesive layers.
<<Base material>>

The pressure-sensitive adhesive tape of the present invention may be provided with a substrate. As the base material, for example, a nonwoven fabric base material or a resin film may be used.

Examples of the nonwoven fabric substrate include nonwoven fabrics obtained using manila hemp, wood pulp, rayon, acetate fiber, polyester fiber, vinylon fiber (polyvinyl alcohol fiber), chemical fibers such as polyamide fiber, and mixtures thereof. be done. Among them, it is more preferable to use a nonwoven fabric produced using 50% or more of plant-derived raw materials.

In addition, a sheet obtained using polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene furanoate, polyolefin, polyacrylate, polyvinyl chloride, polyethylene, polypropylene ethylene vinyl alcohol, polyurethane, polyamide, polyimide, etc. Film: A non-foaming film substrate such as glass can be used. The surface of these substrates may be subjected to antistatic treatment, corona treatment, or the like.

A foam base material may be used as the base material. As the foam substrate, for example, a polyolefin foam, a polyurethane foam, an acrylic foam, and other rubber foams can be used. The surface of the foam substrate may be subjected to antistatic treatment, corona treatment, or the like. Above all, it is more preferable to use the resin film produced using 20% or more of plant-derived raw materials.

Further, the adhesive tape of the present invention may have an intermediate layer, an undercoat layer, and the like as long as the properties of the substrate used in the adhesive tape of the present invention are not impaired.

The thickness of the base material can be appropriately selected depending on the material and form thereof, and is preferably, for example, 1000 μm or less, more preferably about 1 to 1000 μm, particularly preferably about 2 to 500 μm. is more preferably about 3 to 300 μm, particularly preferably about 5 to 250 μm.
<< release liner >>

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 side (or both sides) of the pressure-sensitive adhesive layer, the surface of the pressure-sensitive adhesive layer (adhesive tape) can be protected and stored until the time of use, and workability etc. is also useful.

The release liner is not particularly limited, and conventionally known ones can be appropriately used. For example, in order to impart releasability to at least one side of the substrate (substrate for release liner), for example, a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent (release agent) is used. It is possible to use one on which a release coating layer having been subjected to coating treatment is formed. The base material for the release liner may be of either a single layer or multiple layers.

As the substrate for the release liner, various thin sheets such as plastic films, papers, foams, and metal foils can be used, and plastic films are particularly preferred. Examples of raw materials for plastic films include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene and ethylene-propylene copolymers, and thermoplastic resins such as polyvinyl chloride. Also, plastic films made of polylactic acid, polyester, polyamide, etc. obtained from plant-derived raw materials, and paper can be suitably used.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. Table 1 summarizes the composition of the pressure-sensitive adhesive layer and the list of evaluation results.
(Preparation of polyester resin)

(Preparation of polyester resin (A-1))
In a reaction vessel equipped with a thermometer, stirrer, rectifying column, nitrogen inlet tube and vacuum device, 0.14 equivalents of isophthalic acid, 0.5 equivalents of sebacic acid (derived from biomass), and 0.5 equivalents of azelaic acid (derived from biomass) were added as dicarboxylic acid components. ) 0.5 equivalents, 1.4 equivalents of ethylene glycol (derived from biomass) and 0.05 equivalents of diethylene glycol (derived from biomass) as polyol components, and 0.0064% by weight of germanium dioxide as a catalyst were charged, and the internal temperature was gradually increased to 250 ° C. was raised, and the esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 270° C. and the pressure was reduced to 1.33 hPa, and a polycondensation reaction was carried out over 3 hours to produce a polyester resin (A-1). The weight average molecular weight of the resulting polyester resin (A-1) was 138,000. Further, the polyester resin (A-1) had a biomass degree of 92%.

(Preparation of polyester resin (A-2))
A reactor equipped with a thermometer, stirrer, rectifying column, nitrogen inlet tube and vacuum device was charged with 0.15 equivalents of isophthalic acid, 0.48 equivalents of sebacic acid (derived from biomass), and 0.48 equivalents of azelaic acid (derived from biomass) as dicarboxylic acid components. ) 0.5 equivalents, 1.48 equivalents of ethylene glycol (derived from biomass) and 0.05 equivalents of diethylene glycol (derived from biomass) as polyol components, and 0.0064% by weight of germanium dioxide as a catalyst were charged, and the internal temperature was gradually increased to 250 ° C. was raised, and the esterification reaction was carried out over 4 hours. Thereafter, the internal temperature was raised to 270° C. and the pressure was reduced to 1.33 hPa, and the polycondensation reaction was carried out over 3 hours to produce a polyester resin (A-2). The weight average molecular weight of the resulting polyester resin (A-2) was 56,000. Further, the polyester resin (A-2) had a biomass degree of 92%.

The biomass degree of the polyester resin is a value calculated from the following formula.
<<Biomass degree of polyester resin>>
Biomass degree of polyester resin (% by weight) = 100 × [weight of plant-derived raw materials (g)] / [total weight of raw materials used to prepare polyester resin (g)]
(Example 1)

To 100 parts by weight of the polyester resin (A-1), an adduct of tolylene diisocyanate and trimethylolpropane as a cross-linking agent (DIC Corporation "Barnock D-40", hereinafter abbreviated as "D-40" ) was blended with 1.8 parts by weight to obtain an adhesive with a gel fraction of 48% by weight.

The pressure-sensitive adhesive is applied to the heavy release treated surface of a release liner (release paper with a thickness of 125 μm with release treatment on both sides), dried at 85 ° C. for 3 minutes, and the light release treated surface of another release liner. A pressure-sensitive adhesive layer having a thickness of 50 μm was produced by laminating the adhesive layer. Then, the double-sided pressure-sensitive adhesive tape was obtained by aging in an environment of 40° C. for 96 hours. After that, an evaluation test for adhesive strength and removability evaluation 1 was performed on the double-sided pressure-sensitive adhesive tape. Table 1 shows the details of the evaluation results. <Adhesion evaluation>

After peeling off the release liner (soft release treatment side) of the double-sided adhesive tape, the tape was lined with a polyethylene terephthalate film having a thickness of 25 μm, and cut into a width of 20 mm to obtain a test piece.

The release liner of the test piece was peeled off, attached to the surface of a clean and smooth stainless steel plate, and pressurized by reciprocating a 2 kg roller on the upper surface, according to JISZ-0237, at 23 ° C. and 50 % RH for 1 hour, then using a tensile tester in an atmosphere of 23 ° C. and 50% RH, the adhesive strength to stainless steel (SUS) plate (peeling direction: 180 °, tensile speed: 0.3 m /min) was measured.
<Removability evaluation 1>

A test piece prepared in a test of adhesive strength to a stainless steel (SUS) plate was attached to a stainless steel plate, left for 500 hours in an environment of 60 degrees Celsius and 90% humidity, and then peeled off from the stainless steel plate. It was evaluated according to whether or not it occurred. When interfacial peeling occurred, it was evaluated as having removability, and was indicated by “◯” in Table 1. On the other hand, when peeling off from the stainless steel plate, cohesive failure occurred and no interfacial peeling occurred.

<Biomass degree of adhesive layer>
Table 1 shows the value of the biomass degree of the pressure-sensitive adhesive layer calculated from the following formula.
Biomass degree of adhesive layer (% by weight) = 100 × [weight of plant-derived raw material (g)] / [total weight of adhesive layer (g)]

The biomass degree (% by weight) of the pressure-sensitive adhesive layer is the same as the biomass degree of the pressure-sensitive adhesive used to form the pressure-sensitive adhesive layer, and the "weight of plant-derived raw material (g)" in the above formula is "(solvent ) is synonymous with the weight (g) of the plant-derived raw material contained in the adhesive, and the “total weight (g) of the adhesive layer” is the “total weight (g) of the adhesive (excluding the solvent)” is synonymous with
(Example 2)

By the same procedure as in Example 1, the blending amounts were adjusted as shown in Table 1 to obtain an adhesive. Next, the same procedure as in Example 1 was performed to obtain a double-sided pressure-sensitive adhesive tape. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Example 3)

By the same procedure as in Example 1, the blending amounts were adjusted as shown in Table 1 to obtain an adhesive. Next, the same procedure as in Example 1 was performed to obtain a double-sided pressure-sensitive adhesive tape. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Example 4)

To 100 parts by weight of the polyester resin (A-1), 10 parts by weight of Arakawa Chemical Industries, Ltd. "Super Ester A-100" (biomass degree: 100% by weight) as a tackifier A, and "D-40" as a cross-linking agent 2.4 parts by weight of ', to obtain a pressure-sensitive adhesive with a gel fraction of 45% by weight.

The pressure-sensitive adhesive is applied to the heavy release-treated surface of a release liner (release paper with a thickness of 125 μm with release treatment on both sides) and dried at 85° C. for 3 minutes to form a pressure-sensitive adhesive layer with a thickness of 50 μm. made. Then, the double-sided pressure-sensitive adhesive tape was obtained by aging in an environment of 40° C. for 96 hours. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Example 5)

By the same procedure as in Example 4, the blending amounts were adjusted as shown in Table 1 to obtain an adhesive. Next, a double-sided adhesive tape was obtained in the same manner as in Example 4. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Example 6)

Harima Kasei Co., Ltd. "Haritac PCJ" (biomass content: 95% by weight) was used as the tackifier B, but the procedure was the same as in Example 4, and the amount was prepared as shown in Table 1. Got the adhesive. Next, a double-sided adhesive tape was obtained in the same manner as in Example 4. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.

(Example 7)
2.5 parts by weight of "D-40" as a cross-linking agent was added to 100 parts by weight of the above polyester resin (A-2) to obtain a pressure-sensitive adhesive with a gel fraction of 40% by weight.

The pressure-sensitive adhesive is applied to the heavy release treated surface of a release liner (release paper with a thickness of 125 μm with release treatment on both sides), dried at 85 ° C. for 3 minutes, and the light release treated surface of another release liner. A pressure-sensitive adhesive layer having a thickness of 50 μm was produced by laminating the adhesive layer. Then, the double-sided pressure-sensitive adhesive tape was obtained by aging in an environment of 40° C. for 96 hours. After that, the double-sided pressure-sensitive adhesive tape was subjected to the above-described adhesive strength evaluation and removability evaluation 1 evaluation test. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.

(Example 8)
By the same procedure as in Example 7, the blending amounts were adjusted as shown in Table 1 to obtain an adhesive. Next, a double-sided adhesive tape was obtained in the same manner as in Example 7. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.

(Example 9)
By the same procedure as in Example 7, the blending amounts were adjusted as shown in Table 1 to obtain an adhesive. Next, a double-sided adhesive tape was obtained in the same manner as in Example 7. After that, the double-sided pressure-sensitive adhesive tape was subjected to an evaluation test for adhesion evaluation and removability evaluation 1. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Comparative example 1)

The composition was the same as in Example 4, but the amount of the cross-linking agent was changed to 1.1 parts by weight to obtain a pressure-sensitive adhesive with a gel fraction of 20% by weight. Next, a double-sided adhesive tape was obtained in the same manner as in Example 4. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Comparative example 2)

The composition was the same as in Example 5, but the amount of the cross-linking agent was changed to 1.1 parts by weight to obtain a pressure-sensitive adhesive with a gel fraction of 18% by weight. Next, a double-sided adhesive tape was obtained in the same manner as in Example 4. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.
(Comparative Example 3)

The composition was the same as in Example 6, but the amount of the cross-linking agent was changed to 1.3 parts by weight to obtain a pressure-sensitive adhesive with a gel fraction of 17% by weight. Next, a double-sided adhesive tape was obtained in the same manner as in Example 4. After that, the double-sided pressure-sensitive adhesive tape was subjected to the evaluation test for the adhesive strength evaluation and removability evaluation 1 described above. Table 1 shows the details of the evaluation results. Table 1 shows the biomass degree of the pressure-sensitive adhesive layer calculated from the above formula.

（実施例１０～１５）

(Examples 10-15)

Regarding the double-sided adhesive tapes obtained in Examples 1 to 9, after leaving for 500 hours in an environment of 85 ° C. (without humidity adjustment), when peeling off from the stainless steel plate, the test piece was reprocessed depending on whether interfacial peeling occurred. The peelability was evaluated (removability evaluation 2 below). As a result, the removability of the pressure-sensitive adhesive tapes obtained in Examples 1 to 3 and Examples 7 to 9 was good (○) (test results for Examples 10 to 15, respectively).
<Removability Evaluation 2>

A test piece prepared for a test of adhesive strength to a stainless steel (SUS) plate is left in an environment of 85 degrees Celsius (without humidity adjustment) for 500 hours, and then peeled off from the stainless steel plate. evaluated whether or not

As shown in Table 1, etc., Examples 1 to 15 have a high biomass degree of 80% by weight or more, a gel fraction of 40% by weight or more, and an adhesive force to a stainless steel plate of 4 to 14 N/20 mm. In the removability test, the adhesive tape has interfacial peeling even after being left for 500 hours in a high temperature and high humidity environment of 60 ° C. and 90% (or in a high temperature environment of 85 ° C.), Good removability was exhibited.

On the other hand, in Comparative Examples, it was confirmed that good removability could not be obtained. In the comparative examples, the gel fraction was less than 40% by weight, and cohesive failure (x) was confirmed in the removability test.

The present invention is applicable to portable electronic (electrical) devices such as mobile phones, smart phones, tablet PCs, portable music players, and PDAs, digital cameras, videos, car navigation systems, personal computers, televisions, game machines, air conditioners, etc. It can be used as an adhesive tape used for fixing members such as copiers.

This application claims priority based on Japanese Patent Application No. 2019-225645 filed on December 13, 2019, and incorporates all the descriptions described in the Japanese application.

REFERENCE SIGNS LIST 1 release liner 2 adhesive layer 3 base material

Claims (5)

A pressure-sensitive adhesive layer containing at least a polyester resin, a cross- linking agent, and 0 to 15 parts by weight of a tackifying resin with respect to 100 parts by weight of the polyester resin,
The polyester resin contains isophthalic acid and at least one of sebacic acid and azelaic acid as carboxylic acid components,
The weight average molecular weight (Mw) of the polyester resin is 50,000 to 150,000,
The cross-linking agent is an isocyanate-based cross-linking agent,
The content of the cross-linking agent is 1.4 to 5.0 parts by weight with respect to 100 parts by weight of the polyester resin,
The pressure-sensitive adhesive layer has a biomass degree of 80% by weight or more,
The adhesive layer has a gel fraction of 40% by weight or more,
Adhesive force to stainless steel plate is 4 to 14N/20mm,
After the pressure-sensitive adhesive layer is left for 500 hours in a high-temperature/high-humidity environment of 60°C and 90%,
An adhesive tape characterized by having interfacial peelability. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a gel fraction of 40% to 85% by weight. The pressure-sensitive adhesive tape according to claim 1 or 2 , wherein the polyester-based resin contains isophthalic acid, sebacic acid, and azelaic acid as carboxylic acid components. The pressure-sensitive adhesive tape according to any one of claims 1 to 3 , characterized by having a release liner on at least one side of said pressure-sensitive adhesive layer. The polyester-based resin according to any one of claims 1 to 4 , wherein the carboxylic acid component is a polymer obtained by reacting 1.1 to 2 equivalents of a diol component per equivalent of the carboxylic acid component. Adhesive tape as described.

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