KR20230054488A - Adhesive compositions and adhesive tapes - Google Patents

Abstract

In order to provide a rubber-based adhesive composition having excellent adhesion to various adherends including metals, resins, and coating materials, high-temperature retention, and re-peelability, and an adhesive tape using the same, natural rubber, a crosslinking agent, a tackifier, and a crosslinking regulator are required. A pressure-sensitive adhesive composition comprising a pressure-sensitive adhesive composition, wherein the minimum temperature of the loss tangent after curing of the pressure-sensitive adhesive composition is 78.7°C or higher and the minimum value is 0.20 or less, and the maximum temperature of the loss tangent is 25.0°C or lower and the maximum value is 1.15 or less. It is set as the adhesive tape in which the adhesive layer 12 was formed in at least one surface of the sheet-shaped base material 11 using using.

Description

Adhesive compositions and adhesive tapes

The present invention relates to an adhesive composition using natural rubber as a main component, which has a high degree of crosslinking, excellent cohesiveness and self-adhesive surface adhesiveness, and excellent adhesive strength to various adherends including metals, resins and coating materials, high temperature retention and re-peeling. It relates to an adhesive composition having properties.

In addition, the present invention is an adhesive tape suitable for temporary fixation that uses the above-mentioned adhesive composition, has a strong fixing force required in the manufacturing/assembly stage or transportation stage of an article, has little contamination of the adherend when re-peeling, and is easy to peel. It is about.

In industrial products such as information equipment, office equipment, household appliances, and interiors, adhesive tape is applied directly to the article for the purpose of masking, reinforcement, protection, identification during manufacturing or assembly, and damage prevention and packing assistance during transportation after manufacturing. It is attached and pulled off after achieving the purpose. Therefore, such an adhesive tape for temporary fixing has excellent fixing power to an adherend (adhesion, high temperature retention) and less contamination of an adherend when peeled (also referred to as re-peeling) (repeelability). Contrary performance is required.

In addition, in order to facilitate peeling of the tape and further enhance re-peelability, it is required to be capable of holding the end of the tape folded back to the unwound surface side (self-adhesive surface adhesiveness) as a handle at the time of tape re-peeling.

As an adhesive suitable for the adhesive tape for temporary fixing used for such a purpose, an acrylic or rubber type adhesive can be mentioned from a viewpoint of performance and price.

Patent Literature 1 describes that the pressure-sensitive adhesive layer was obtained by curing an isoprene-based rubber and a tackifier with a curing agent in the presence of a zirconium compound. Patent Document 2 describes that a primer layer composed of a composition containing a rubber component composed of natural rubber obtained by polymerizing methyl methacrylate, an isocyanate compound, and an aminoethylated acrylic resin is formed between a rubber-based pressure-sensitive adhesive layer and a substrate. . Patent Literature 3 describes PSA sheets in which a layer made of a solid type PSA composition obtained by adding a tackifier to a rubbery polymer and crosslinking with an isocyanate-based crosslinking agent is described.

Japanese Unexamined Patent Publication No. 2014-034582 Japanese Unexamined Patent Publication No. 2014-240484 Japanese Unexamined Patent Publication No. 2001-181596

In Patent Document 1, it is said that the cohesive force of the pressure-sensitive adhesive is increased by using an organozirconium compound as a zirconium compound and curing with an isocyanate-based curing agent as a curing agent, but even if an organozirconium compound is used, the gel fraction is low (17 to 30%) , since the measurement conditions are unclear, it is expected that the high-temperature holding power and paste persistence, which are the targets of the present invention, will be inferior.

In Patent Document 2, as a preferred embodiment, the pressure-sensitive adhesive layer is an elastomer containing 50 to 80 parts by weight of natural rubber and 20 to 45 parts by weight of isoprene rubber having a peroxide in the molecule, 50 to 100 parts by weight of a tackifying resin, and a crosslinking agent It contains 0.1 to 15 parts by weight, and by combining with the specific primer layer described above, it has strong adhesive strength and is said to significantly suppress contamination such as glue residue on the adherend when the tape is peeled off. In addition, by adding liquid isoprene rubber having a peroxide in the molecule, sulfur and peroxides commonly used for crosslinking (vulcanization) of natural rubber are not used, and curing at 120 ° C or higher is not required, and storage environment at normal temperature and humidity It is said that crosslinking in Moreover, although it is described that an epoxy resin, an isocyanate resin, etc. are used as a crosslinking agent, it is preferably an epoxy resin (paragraph 0023). In the examples, although an isocyanate compound is used for the primer layer, the crosslinking agent of the pressure-sensitive adhesive layer is epoxy-based, and the pressure-sensitive adhesive layer is crosslinked using not only pure natural rubber but also liquid isoprene rubber having a peroxide in the molecule. Since the pass/failure of the gel fraction is set as low as 20%, and the pass/failure of the holding power measurement conditions is also low, it is difficult to say that the holding power is sufficient for the purpose of the present invention.

The pressure-sensitive adhesive composition of Patent Document 3 is a solvent-free, solid type composition obtained by adding a tackifier and an isocyanate-based crosslinking agent to a rubbery polymer made of natural rubber, heat-kneading at 80 to 120°C, and crosslinking. By researching a heat-kneading method, it is possible to realize moderately weak crosslinking even with a solid type using an isocyanate-based crosslinking agent, increase cohesive force while maintaining adhesive force, and do not cause low molecular weight even with the addition of a small amount of crosslinking agent. It has been found to be evenly distributed. However, in Patent Literature 3, an adhesive force test by peeling at 23 ° C. and a holding force test by a 2 kg load at 40 ° C. are conducted, but the properties at high temperatures are not further evaluated.

Further, in the past, tapes for temporary fixing of articles using acrylic adhesives having excellent fixing and cohesive strength have been studied, but acrylic adhesives have insufficient self-adhesive surface adhesion and have high adhesive strength to metal or glass. , there is a concern about contamination of the adherend at the time of re-peeling.

An object of the present invention is to provide a rubber-based adhesive composition having excellent adhesive strength, high-temperature retention, and low staining properties to various adherends including metals, resins, and coating materials.

In addition, in the present invention, by using a rubber-based pressure-sensitive adhesive, contamination of the adherend after re-peeling is reduced even when exposed to a high temperature or high temperature and high humidity environment in the manufacturing/assembly step or transport step of the article, and also as a handle at the time of tape re-peeling. It is an object of the present invention to provide an adhesive tape for temporary fixing, which is easy to peel because it can be held in a state where the end of the tape is folded back to the unwinding side, and which can sufficiently temporarily fix an article even with a narrow width because it has excellent adhesive strength.

An adhesive composition according to one aspect of the present invention is an adhesive composition containing a natural rubber, a crosslinking agent, a tackifier, and a crosslinking regulator, and the minimum temperature of the loss tangent after curing of the adhesive composition is 78.7°C or higher and the minimum value is 0.20 or less. In addition, the maximum temperature of the loss tangent is 25.0 ° C. or less, and the maximum value is 1.15 or less.

Moreover, the adhesive tape which concerns on another aspect of this invention is an adhesive tape which has the adhesive layer which consists of the said adhesive composition on at least one surface of a sheet-like base material.

According to one aspect of the present invention, a rubber-based adhesive composition having excellent adhesion to various adherends including metals, resins, and coating materials, high-temperature retention, and re-peelability (low contamination) is provided.

In addition, according to another aspect of the present invention, an adhesive tape suitable for temporary fixation that has a strong fixing force required in the manufacturing/assembly step or transportation step of an article, has little contamination of the adherend when re-peeling, and is easy to peel is provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing an example of a configuration of an adhesive tape to which an aspect for carrying out the invention is applied.
Fig. 2 is a diagram showing another configuration example of an adhesive tape to which the mode for carrying out the invention is applied.

An adhesive composition according to an embodiment of the present invention will be described.

The adhesive composition according to the present embodiment is an adhesive composition containing natural rubber, a crosslinking agent, a tackifier, and a crosslinking regulator, and the minimum temperature of the loss tangent after curing of the adhesive composition is 78.7°C or more and the minimum value is 0.20 or less, and the minimum value is 0.20 or less. Characterized in that the maximum temperature of the loss tangent is 25.0 ° C or less and the maximum value is 1.15 or less.

<loss tangent>

The loss tangent (loss modulus (G")/storage modulus (G') = loss tangent (tan δ)) means the degree of contribution of the loss modulus (viscosity) to the storage modulus (elasticity).

When the minimum temperature of the loss tangent after curing of the present adhesive composition is 78.7° C. or higher, the minimum value of the degree of contribution of the loss elastic modulus (viscosity) is small and the temperature at which the cured product made of the present adhesive composition has a predetermined hardness is high, that is, the present adhesive composition It shows that the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition maintains appropriate hardness even at a relatively high temperature. When the minimum temperature of the loss tangent is less than 78.7 ° C, the holding power at high temperatures is inferior.

In addition, the fact that the minimum value of the loss tangent after curing of the present adhesive composition is 0.20 or less indicates that the cured product (adhesive layer) of the present adhesive composition is difficult to soften excessively and is difficult to flow.

Further, the maximum temperature of the loss tangent represents the glass transition temperature, and the fact that the maximum temperature of the loss tangent of the present adhesive composition is 25.0 ° C. or less indicates that the cured product of the present adhesive composition has a low glass transition temperature and maintains moderate flexibility even at low temperatures. .

In addition, the maximum value of the loss tangent represents peel resistance, and the maximum value of the loss tangent of the cured product of the present adhesive composition is 1.15 or less, the peel resistance when used as an adhesive layer is small, and the adhesive tape using the present adhesive composition is easy to peel indicate

Each component is explained.

<natural rubber>

Natural rubber is obtained by coagulating and drying natural rubber latex, which is the sap of a rubber tree, and is a substance containing cis-1,4-polyisoprene as a main component.

In the structure of a natural rubber molecule, one end of a cis-1,4-isoprene unit is composed of a protein terminal, the other end is bound to a phospholipid, and a long-chain fatty acid is further bound to the end of the phosphate lipid. It is said to be rescued.

Moreover, 3-4 mass % of non-rubber components, such as a protein and a lipid, are contained in natural rubber.

For this reason, natural rubber can be easily crosslinked and cured with a crosslinking agent described later. In addition, since the pressure-sensitive adhesive composition according to the present invention is cured by crosslinking, the crosslinked product is also referred to as a cured product.

Classification of natural rubber used includes, for example, Standard Malaysian Rubber (SMR), Standard Indonesian Rubber (SIR), Ribbed Smoked Sheet (RSS) No. 1 to 6, Pail Crepe No. 1 to 3, etc. there is.

Also, in general, unroasted natural rubber has a very high molecular weight, and when the molecular weight of natural rubber is too high, the degree of plasticity is high. There may be cases where it does not exist.

For this reason, it is necessary to mechanically knead in advance with a pressurized kneader, a Banbury mixer, an open roll, etc. to appropriately lower the molecular weight of natural rubber to adjust the degree of plasticity, and then use it for compounding.

In particular, as the plasticity of the natural rubber used in the pressure-sensitive adhesive composition of the present invention, the Mooney viscosity ML ₁₊₄ (100°C) is preferably 10 to 85, more preferably 20 to 35. If the degree of plasticity is too low or too high, it may not be possible to obtain an adhesive composition and adhesive tape that achieve both excellent adhesive strength and high cohesive force required for temporary fixing of articles.

<Crosslinking agent>

As methods of crosslinking natural rubber, a method of vulcanization using a vulcanizing agent and a method of crosslinking by reaction between functional groups are known.

In the vulcanization method, a sulfur-based, thiuram-based, quinoid-based vulcanizing agent acts on the unsaturated bonds contained in the molecular main chain of natural rubber, and takes a reaction mechanism in which polymers are directly crosslinked, so that the cohesive force is large and dense. Strong cross-linking is feasible.

However, since it is a direct strong crosslinking mechanism, the tackiness rapidly decreases with an increase in the degree of vulcanization, and the adhesive strength also decreases remarkably. In addition, sulfur powder is known as a component that may cause metal corrosion, and is not preferable for temporary fixing applications in which it is directly applied to various adherends including metals, resins, and coating materials.

On the other hand, in the crosslinking method by reaction between functional groups, functional groups such as hydroxyl groups and carboxyl groups that may be introduced into molecular side chains during the production process of natural rubber, proteins, lipids, etc. A multifunctional compound having a functional group of a non-rubber component and a functional group that reacts thereto is added, and crosslinking is performed by a reaction between the functional groups.

In this method, it is known that it is possible to use a crosslinking agent containing, for example, an isocyanate-based compound, an epoxy-based compound, an oxazoline-based compound, an aziridine-based compound, a butylated melamine compound, or the like as the crosslinking agent.

In addition, since non-sulfur-based crosslinking agents that are not vulcanizing agents do not contain sulfur that may cause metal corrosion, they are more suitable for temporary fixing applications directly applied to various adherends including metals, resins, and coating materials.

The present inventors thought that if natural rubber can be crosslinked softly and densely, it is possible to provide a rubber-based pressure-sensitive adhesive that has excellent adhesive strength required for temporary fixing of articles and has high cohesive force and is excellent in high-temperature retention and re-peelability. . Then, in order to achieve this object, on the basis of the above-described common knowledge, a crosslinking agent characterized by being non-sulfuric and capable of high crosslinking was studied by trial and error.

As a result, the inventors of the present invention found that, among the above crosslinking agents, by using a crosslinking agent containing an isocyanate-based compound as a main component, natural rubber can be flexibly and densely crosslinked as an adhesive composition having excellent adhesive strength required for temporary fixing of an article. found something

In addition, by using a crosslinking agent containing at least one compound selected from those containing a diphenylmethane diisocyanate structure (polymeric MDI) as a main component among the isocyanate-based compounds, excellent adhesive strength to various adherends, high temperature retention, It has been found that a rubber-based pressure-sensitive adhesive having releasability can be provided.

That is, the crosslinking agent used in the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present invention contains an isocyanate-based compound as a main component, and particularly contains at least one compound selected from those containing a diphenylmethane diisocyanate structure as a main component. It can be used preferably.

The crosslinking agent can be used in an amount of 1 to 15 parts by mass, preferably 2.5 to 10 parts by mass, based on 100 parts by mass of natural rubber. By using within the range of the amount, each characteristic of the loss tangent can be satisfied.

<tackifier>

In the adhesive composition of the present embodiment, a tackifying resin having good compatibility with natural rubber can be used as the tackifier, and in particular, from the group consisting of petroleum resins with a softening point of 125 ° C. or higher, terpene resins, rosin resins and other resins. At least one selected resin can be used. It is especially preferable that it is a petroleum resin (saturated aliphatic hydrocarbon resin) with a softening point of 125 degreeC or more. Such a tackifier can be used by adding 50 to 100 parts by mass, preferably 60 to 90 parts by mass, based on 100 parts by mass of natural rubber.

When a tackifying resin having a softening point lower than 125 ° C. is used as a tackifier, an adhesive composition and adhesive tape having excellent adhesive strength, high temperature retention and releasability required for temporary fixing of articles may not be obtained.

In addition, even when the addition amount of the tackifier is too large or too small, there are cases where an adhesive composition and an adhesive tape having the above physical properties cannot be obtained.

<Crosslinking regulator>

In the pressure-sensitive adhesive composition of the present embodiment, the degree of crosslinking (gelation degree) of the composition is adjusted by using a crosslinking regulator. This is used for the purpose of realizing an appropriately flexible and dense crosslinking reaction within a range in which the excellent adhesive strength, high cohesive force and high temperature holding power of the adhesive composition are compatible. In particular, in the present invention, a compound that inhibits the reaction between an isocyanate compound as a crosslinking agent and a hydroxyl group of natural rubber to some extent or the like is used as a crosslinking regulator.

In the adhesive composition of the present embodiment, at least one compound selected from the group consisting of a hindered phenol-based compound, a phosphorus-based compound, a metal-based compound, a benzotriazole-based compound, a triazine-based compound, and a hindered amine-based compound is used as a crosslinking regulator can be added and used.

As a hindered phenolic compound, specifically, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2'-thiodiethyl Bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionic acid- n-octadecyl, N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], octyl-3,5- Di-tert-butyl-4-hydroxy-hydrocinnamic acid, 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene, 2,4-bis (octylthiomethyl)-6-methylphenol, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid] [ethylenebis(oxyethylene)], 1,6-hexanediolbis[ 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1 ,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4-[[4,6-bis(octylthio)-1,3,5-triazine-2-yl ] amino] -2,6-di-tert-butyl phenol; and the like.

Moreover, as a phosphorus compound, tris (2, 4- di- tert- butylphenyl) phosphite is mentioned specifically,. As a metal compound, specifically, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxy phenyl) propanoyl] propane hydrazide. As a benzotriazole type compound, specifically, 4-methyl-2-(2H-benzotriazol-2-yl)phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis( 1-methyl-1-phenylethyl)phenol, 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol, 2,2'- methylene bis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] and benzotriazolyldodecyl p-cresol. As a triazine type compound, 2-(4,6-diphenyl- 1,3,5-triazin-2-yl) -5- (hexyloxy) phenol is mentioned specifically,. As a hindered amine compound, specifically, poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-S-triazine-2,4-diyl]-[(2, 2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidyl)imino], dimethyl succinate 1- (2hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine polycondensate, 2-[[3,5-bis(1,1-dimethylethyl)-4 -Hydroxyphenyl] methyl] -2-butylpropanedioic acid bis [1,2,2,6,6-pentamethyl-4-piperidinyl], sebacic acid bis (1,2,2,6,6- pentamethyl-4-piperidyl), sebacic acid 1-methyl 10-(1,2,2,6,6-pentamethyl-4-piperidyl), and the like. Among them, a preferred crosslinking modifier is at least one compound selected from the group consisting of hindered phenolic compounds.

The amount of the cross-linking regulator is not particularly set, but if the amount of the cross-linking regulator is too large, the natural rubber cannot be made soft and densely cross-linked, so that excellent adhesive strength required for temporary fixing of articles, high cohesive force, and high temperature retention are compatible. There are cases where an adhesive composition and an adhesive tape cannot be obtained. Moreover, when there is too little, the effect of adding a crosslinking regulator may not fully be exhibited. It is preferably 1.0 parts by mass or more and 5.0 parts by mass or less, more preferably 2.0 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of natural rubber.

<Other additives>

In the adhesive composition, if necessary, within a range that does not impair the physical properties, inorganic fillers, organic fillers such as resins, softeners, plasticizers, surfactants, coupling agents, colorants, preservatives, heat stabilizers, light stabilizers, etc. 1 type or 2 or more types may be further added.

In this specification, "adhesive composition" means both a mixture of each component before crosslinking and a composition after crosslinking, and the "adhesive layer" in the following adhesive tape is made of this adhesive composition, in that case, "Adhesive composition" means the composition after crosslinking. Moreover, in order to form an adhesive layer, the state melt|dissolved and disperse|distributed in the solvent and the dried material from which the solvent was removed may also be called "adhesive composition."

[adhesive tape]

Moreover, the adhesive tape of this invention is an adhesive tape in which the adhesive layer which consists of the said adhesive composition is formed on at least one surface of a sheet-shaped base material. For example, as shown in FIG. 1, a single-sided adhesive tape in which an adhesive layer 12 made of the pressure-sensitive adhesive composition is formed on one side of a base material 11, or a single-sided adhesive tape formed on both sides of a base material 21 as shown in FIG. 2 It is a double-sided tape using the said adhesive composition for at least one or both of the adhesive layer 22 and the adhesive layer 23.

The pressure-sensitive adhesive layer 12 in FIG. 1 or the pressure-sensitive adhesive layers 22 and/or 23 in FIG. 2 is a coating solution obtained by dissolving or dispersing an adhesive composition in a suitable solvent on a sheet-like base material 11 or 12. It can be formed by coating using a roll coater, a die coater, etc., or by co-extruding an adhesive composition with these base materials without using a solvent. Preferably, a coating solution in which natural rubber, a crosslinking agent, a tackifier, a crosslinking regulator, and other additives are mixed and dissolved in a solvent such as toluene is prepared, and this coating solution is applied to one side of the substrate 11 or the substrate ( 21) is applied to one or both surfaces using a coater or the like so that the thickness of the pressure-sensitive adhesive layer after drying becomes uniform, and then the coated pressure-sensitive adhesive composition is dried and cured at a predetermined temperature.

The thickness of the pressure-sensitive adhesive layer after drying and curing is not particularly limited, and may be any that exhibits excellent adhesive strength, self-adhesive surface adhesion, cohesion, and high temperature retention required for temporary fixing of articles, but is usually 10 to It is about 70 μm, preferably 25 to 50 μm.

In addition, surface treatment such as corona discharge treatment is given to the surface (surface 11A) facing the pressure-sensitive adhesive layer 12 of the sheet-like base material 11 in FIG. 1, or an undercoat layer is formed as needed. , The adhesiveness with respect to the base material 11 of the adhesive layer 12 can be improved by performing both. In addition, by forming a release layer as necessary on the surface 11B on the opposite side of the surface 11A of the sheet-like substrate 11 in FIG. 1, when the adhesive tape of the present embodiment is wound in a roll shape, the substrate ( While preventing adhesion of the pressure-sensitive adhesive composition to the surface 11B of 11), it is possible to maintain ease of rewinding (withdrawal).

In addition, surface treatment such as corona discharge treatment is applied to both surfaces 21A and 21B of the sheet-like substrate 21 in FIG. 2 or any one surface, an undercoat is formed, or both are performed. By doing it, the adhesiveness of the adhesive layer 22 or the adhesive layer 23 and the base material 21 can be improved.

<Material on the sheet>

The type of the sheet-like base material described above is not particularly limited, and any sheet-like material may be used, such as a commonly used known film or non-woven material such as foam, woven fabric, knitted fabric, or paper.

Among them, a resin film substrate is preferable, and as a resin material, polyethylene (PE), polypropylene (PP), oriented polypropylene (OPP), polyester, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene naphthalate (PEN), polyphenylene sulfide, ethylene-vinyl acetate copolymer (EVA), and blends thereof. In the case of a film made of such a synthetic resin, it has excellent mechanical strength and does not cause contamination of adherends, and is suitable as an adhesive tape for temporary fixing used in manufacturing/assembling steps or transport steps of articles.

In addition, the thickness of the sheet-shaped base material can also be appropriately selected and used within the range that can maintain the strength required for the adhesive tape, but the thickness is preferably 10 to 300 μm, more preferably 10 to 100 μm, and 12 to 75 μm It is more preferable to be In particular, in the case of polyethylene terephthalate (PET) film in its thickness range, it has excellent mechanical strength, exhibits high fixing power, and does not cause contamination of adherends, for temporary fixing used in the manufacturing/assembly stage or transportation stage of products. It is more preferable as an adhesive tape for

＜Submersible agent＞

The undercoating agent used for the undercoating layer is not particularly limited, and any one may be used as long as it exhibits the effect. In particular, if it has a functional group capable of reacting with the functional group of the compound contained in the pressure-sensitive adhesive layer, the reaction proceeds to the undercoat layer during crosslinking when forming the pressure-sensitive adhesive layer, and the adhesive strength with the substrate can be increased. The adhesion amount or basis weight of the undercoating layer after drying is usually 0.2 to 2 g/m 2 , preferably 0.4 to 1.2 g/m 2 .

<release treatment agent>

As shown in FIG. 1 , when the pressure-sensitive adhesive layer 12 is formed on one surface 11A of the base material 11 and wound in a roll shape, the pressure-sensitive adhesive layer comes into contact with the other surface 11B of the base material. It is preferable to form a release layer on the surface 11B in order to improve the pull-out property from the roll. The release treatment agent used for this release layer is not particularly limited, and any one may be used as long as the effect is exhibited. For example, silicone resins, long-chain alkylvinyl monomer polymers, fluorinated alkylvinyl monomer polymers, polyvinyl alcohol carbamates, and the like are known. Among them, the silicone resin is excellent in the property of improving the peeling performance of the surface of the substrate. The adhesion weight or basis weight of the release layer after drying is usually 0.2 to 2 g/m 2 , preferably 0.4 to 1.2 g/m 2 .

<release sheet>

In the case of a double-sided pressure-sensitive adhesive tape as shown in Fig. 2, it is preferable from the viewpoint of handleability that a release sheet is laminated on the outer surface of the pressure-sensitive adhesive layer in a peelable manner. Moreover, when winding in roll shape, it can wind so that a release sheet may be pinched between the adhesive layer 22 and the adhesive layer 23. Since the release sheet does not require very high strength, a sheet-like article subjected to the release treatment as described above can be used on one side or both sides.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In addition, in the following description, "part" means "part by mass".

Materials used in Examples and Comparative Examples are as follows. In addition, the physical property value of each material is the manufacturer's catalog value.

Substrate: PET film (thickness 38 ㎛)

Natural Rubber: Pale Crepe

(using different grades of Mooney viscosity listed in the table)

Crosslinking agent:

A Product name “Millionate MR-200”,

Toso Manufacturing, Polymeric MDI

B Product name "Colonate L-45E",

Toso Manufacturing, Modified Polyisocyanate

C Trade name "E-5C", Soken Chemical Co., Ltd., epoxy-based crosslinking agent

D Product name 「Vulkacit Thiuram/C」, LANXESS Co., Ltd.

Thiuram-based vulcanizing agent (tetramethylthiuram disulfide)

Tackifier:

A Product name "Pencell D-135", manufactured by Arakawa Chemical Industry,

Polymerized rosin ester, softening point 130 ~ 140 ℃

B Product name "Arcon P-140", manufactured by Arakawa Chemical Industry,

Petroleum resin, softening point 140 ℃ ± 5 ℃

C Product name "Arcon P-100", manufactured by Arakawa Chemical Industry,

Petroleum resin, softening point 100 ℃ ± 5 ℃

Crosslinking regulator: trade name "Irganox 1010", manufactured by BASF Japan;

(Hindered phenolic compound)

(Examples 1 to 8, Reference Example 1, Comparative Examples 1 to 12)

An adhesive composition was prepared at the compounding ratio shown in Table 1 (Table 1-1 and Table 1-2), and dissolved and mixed in toluene to prepare a coating solution. On one side of the base material, a primer (polymethyl methacrylate grafted natural rubber (manufactured by Malaysian Rubber Institute, trade name "MG30") and cyclized rubber (manufactured by Yushibi Japan, trade name "ALPEX CK-450") were mixed in a mass ratio of 3: 1 toluene solution with a solid content of 5% by mass) was applied, and after forming an undercoat layer having a basis weight of 0.8 ± 0.4 g / m 2, the prepared coating solution was applied so that the thickness of the pressure-sensitive adhesive layer after drying was 32 μm, and 110 By drying and crosslinking at °C, a pressure-sensitive adhesive tape having a single-sided pressure-sensitive adhesive layer as shown in Fig. 1 was prepared.

The following evaluation was performed about the obtained adhesive tape.

(loss tangent)

Using each adhesive composition, an adhesive layer (thickness: 2 mm) for measurement was produced, respectively.

Then, the pressure-sensitive adhesive layer was punched out to a diameter of 10 mm, and what was fixed in a form sandwiched between parallel plates was used as a measurement sample.

For this measurement sample, a dynamic viscoelasticity measurement was performed under the following conditions using a dynamic viscoelasticity measuring device, a temperature dependence graph of the loss modulus (G") and the storage modulus (G') was prepared, and the loss modulus (G") /Storage modulus (G') = The minimum temperature, minimum value, maximum temperature, and maximum value were obtained from the loss tangent (tan δ). Further, as an evaluation, "Y" is not satisfied when the minimum side (minimum temperature is 78.7 ° C. or more and the minimum value is 0.20 or less) and maximum side (minimum temperature is 25 ° C. or less and maximum value is 1.15 or less) satisfy the specified range. The case where it was not was set as "N".

Apparatus: manufactured by TA Instruments, trade name "ARESRDA-III"

Frequency: 10.0 ㎐

Temperature: -60 to 200 ℃

Heating temperature: 10 °C/min

Strain: 0.1%

(adhesiveness)

Adhesive force was measured using the test method based on JIS Z 0237:2000.

As the adherend, PS (polystyrene), PP (polypropylene), PC (polycarbonate), rough surface PC (one surface processed into a mat, manufactured by Takiron Sea Co., Ltd., trade name "PCSP K6600"), glass, SUS board (# SUS304 plate polished with 280 water resistant abrasive paper until the surface becomes uniform), Al plate, acrylic coated plate (SPCC-SB acrylic coated plate manufactured by Nippon Steel Co., Ltd. (Paint: "Newarklose Black Glossy" manufactured by Dainippon Paint Co., Ltd.) )) was used.

Since the adhesive strength of the adhesive composition in the present embodiment is preferably, for example, 2.0 N/10 mm or more and 8 N/10 mm or less, the case where the adhesive force in this range is shown with respect to all adherends is "A", 1 Although the number of adherends fell outside the range, those that were able to maintain this range for other adherends were evaluated as "B", and those that fell outside this range for two or more adherends were evaluated as "C".

(high temperature holding power)

At a measurement temperature of 120 ° C., a weight with a load of 500 g was vertically applied to the longitudinal end of a test piece having a length of 25 mm and a width of 10 mm attached to a SUS plate, and the time until the weight fell was evaluated. A fall time of 120 minutes or more was evaluated as "A", 60 minutes or more and less than 120 minutes as "B", and less than 60 minutes as "C".

(substrate contamination)

An adhesive tape was affixed to each adherend used for the measurement of adhesive strength, left in an atmosphere of 65°C and 85%RH for 7 days or more, then left in an atmosphere of 5°C for 2 hours or more to cool, and then the adhesive tape was removed by hand in an atmosphere of 5°C. It was peeled off from the adherend, and the presence or absence of glue residue or staining on the adherend was visually inspected.

"A" is for the case where no glue residue, tape traces or contamination are visible, "B" is for the case where almost no paste residue, tape traces or contamination is visible, and "C" is for the case where paste residue, tape traces or contamination are clearly visible. 」 was judged.

(Self-adhesive surface adhesiveness)

An adhesive tape was affixed to the adherend, and the end was bent 5 mm toward the adhesive face side, and then left in an 85% RH atmosphere at 65°C for one day or more, and then the peel length of the bent end was visually measured.

(comprehensive evaluation)

In all evaluations, rank A is included, rank B is 2 or less as "A", rank A is included, rank B is 3 or 4 as "B", rank A is included, rank B is 5 A dog was evaluated as "C" and a case containing a rank D was evaluated as "D".

[Table 1-1]

[Table 1-2]

[Table 2-1]

[Table 2-2]

<Evaluation results>

As shown in Tables 1-1 and 1-2, compositions satisfying the loss tangent specified in the present invention were obtained in Examples, but not compositions satisfying either or both of the minimum and maximum sides in Comparative Examples. .

Further, as shown in Table 2-1, the adhesive tapes of Examples 1 to 9 were excellent in all of adhesive strength, high temperature holding power, adherend staining property, and self-adhesive surface adhesion.

On the other hand, in Comparative Examples 1, 2, and 7 to 12, as shown in Table 2-2, the adhesive strength was excellent, but the high-temperature holding power was inferior. Comparative Examples 3 and 4 were excellent in high temperature holding power, but were inferior in adhesive strength. Comparative Examples 5 and 6 were inferior in both adhesive strength and high temperature holding power. In addition, all the comparative examples included the case where it became rank D in adherend contamination property, and was low in versatility.

The adhesive tape of the present invention is an adhesive tape for temporary fixing, and has excellent adhesive strength to various adherends (articles) and is highly versatile in that it exhibits low contamination.

11, 21: description
12, 22, 23: adhesive layer

Claims (10)

An adhesive composition containing natural rubber, a crosslinking agent, a tackifier, and a crosslinking regulator, wherein the adhesive composition has a minimum temperature of a loss tangent after curing of 78.7°C or more and a minimum value of 0.20 or less, and a maximum temperature of the loss tangent of 25.0°C. or less and the maximum value is 1.15 or less. According to claim 1,
The adhesive composition in which the natural rubber has a Mooney viscosity ML ₁₊₄ (100°C) of 20 to 85. According to claim 2,
The adhesive composition in which the natural rubber has a Mooney viscosity ML ₁₊₄ (100°C) of 20 to 35. According to any one of claims 1 to 3,
The adhesive composition in which the said crosslinking agent is a non-sulfur type crosslinking agent. According to claim 4,
The adhesive composition in which the said crosslinking agent contains an isocyanate type compound. According to claim 5,
The isocyanate-based compound has a diphenylmethane diisocyanate structure. According to any one of claims 1 to 6,
The tackifier is a pressure-sensitive adhesive composition composed of a petroleum-based resin having a softening point of 125 ° C. or higher. According to any one of claims 1 to 7,
The adhesive composition in which the crosslinking regulator is at least one compound selected from hindered phenol-based compounds, phosphorus-based compounds, metal-based compounds, benzotriazole-based compounds, triazine-based compounds, and hindered amine-based compounds. According to any one of claims 1 to 8,
An adhesive composition containing 1 to 15 parts by mass of the crosslinking agent, 50 to 100 parts by mass of the tackifier, and 1 to 5 parts by mass of the crosslinking regulator, based on 100 parts by mass of the natural rubber. An adhesive tape having an adhesive layer comprising the adhesive composition according to any one of claims 1 to 9 on at least one surface of a sheet-shaped substrate.

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