JP4515745B2 - Adhesive composition and adhesive tape - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition using a styrene-butadiene rubber or the like as a pressure-sensitive adhesive component, and more specifically, excellent storage stability in a solution state, and when used as a pressure-sensitive adhesive tape, the adhesive strength over time. The present invention relates to a pressure-sensitive adhesive composition in which deterioration of the pressure is suppressed, and a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition.

  In general, in a polyvinyl chloride pressure-sensitive adhesive tape or sheet (hereinafter, also simply referred to as an adhesive tape) whose substrate is made of a polyvinyl chloride resin composition, styrene-butadiene rubber (hereinafter referred to as “SBR”) is used as an adhesive component. The SBR is excellent in low water absorption and aging resistance, but has one aspect that the adhesiveness and cohesion are slightly low. Adhesives containing a mixture with natural rubber as an adhesive component are widely used (see Non-Patent Document 1). However, there are various grades of commercially available SBR, and depending on the grade, it has been difficult to sufficiently solve the insufficient cohesive strength of the pressure-sensitive adhesive only by mixing SBR with natural rubber.

Therefore, the present inventors have previously proposed a method of making up for the lack of cohesive force by adding an isocyanate compound to an adhesive component in which SBR and natural rubber are mixed. However, in this case, the isocyanate compound remaining unreacted in the pressure-sensitive adhesive solution gradually increases the viscosity of the pressure-sensitive adhesive solution by accelerating the reaction in the system. There is a problem that the storage stability in the solution state is lacking and the pot life of the pressure-sensitive adhesive solution cannot be prolonged. Furthermore, when used as an adhesive for adhesive tapes, the cohesive force of the adhesive increases with time, so the unwinding force is reduced when the adhesive tape is wrapped around an adherend such as an electric wire. As a result, there is a problem that the workability may be reduced, or the adhesive tape may be peeled off from the end after the adhesive tape is wrapped around the adherend due to the decrease in adhesive strength over time (terminal peeling). there were.
Edited by Japan Adhesive Tape Industry Association Adhesive Handbook Editorial Committee “Adhesive Handbook (2nd edition)” Japan Adhesive Tape Industry Association, October 12, 1995, p. 461-467

  Accordingly, the present invention has been made in view of the above problems, and the object is to use a mixture of various SBR and natural rubber as an adhesive component of an adhesive and add an isocyanate compound to the adhesive component. However, when used as an adhesive for an adhesive tape, the adhesive has a cohesive force when the adhesive tape is wrapped around an adherend such as an electric wire. With the increase in days, the unwinding force is reduced and the workability is reduced, or the end of the adhesive tape is peeled off after the adhesive tape is wound around the adherend due to the decrease in adhesive strength over time. It is in providing the adhesive composition which does not produce this, and the adhesive tape using the said adhesive composition.

  Therefore, the inventors of the present invention have made extensive studies in order to achieve the above object, and by using a combination of an isocyanate compound and a monohydric alcohol in an adhesive component obtained by mixing SBR and natural rubber as an adhesive composition, It was found that a pseudo-crosslinking reaction caused by self-condensation of unreacted isocyanate compounds in the system can be suppressed. As a result, in the solution state of the pressure-sensitive adhesive composition (hereinafter also referred to as “pressure-sensitive adhesive solution” or simply “pressure-sensitive adhesive”), the change in solution viscosity over time is suppressed, Stable storage is possible, and when used as an adhesive for adhesive tape, the adhesive tape is wrapped around an adherend such as an electric wire, preventing the unwinding force of the adhesive tape from being reduced, Finding that the adhesive tape has an effect of suppressing terminal peeling after the adhesive tape is wound around the adherend due to a decrease in adhesive strength over time, and completes the adhesive composition and adhesive tape of the present invention. It came to.

  That is, the present invention provides an adhesive composition comprising SBR and natural rubber as essential components as an adhesive component, and comprising an isocyanate compound and a monohydric alcohol in the adhesive component. is there.

  In the pressure-sensitive adhesive composition of the present invention, the proportion of the isocyanate compound is 0.1 to 40 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive component, and the monohydric alcohol is an isocyanate group content (I ) (Mol) and the hydroxyl group content (II) (mol) of the monohydric alcohol are contained so as to have the relationship of the following formula (1).

0.01 ≦ (I) / (II) ≦ 100 (1)
Furthermore, this invention relates to the adhesive tape which has an adhesive layer which consists of the said adhesive composition on the at least single side | surface of a base material.

  The pressure-sensitive adhesive composition according to the present invention contains SBR and natural rubber as essential components of the pressure-sensitive adhesive component, and an isocyanate compound and a monohydric alcohol are mixed with the pressure-sensitive adhesive component. Therefore, various grades of SBR are used as the SBR. Even when used, the solution viscosity of the adhesive does not change over time, allowing stable storage over a long period of time, and when used as an adhesive for adhesive tape, aggregation over time In order to suppress an increase in force, good adhesive force in the initial stage of adhesion can be maintained, and the adhesive tape can exhibit excellent adhesive properties to the adherend without lowering the rewinding force of the adhesive tape and causing terminal peeling. .

  Hereinafter, the present invention will be described in detail. The present invention relates to a pressure-sensitive adhesive composition containing SBR and natural rubber as essential components of a pressure-sensitive adhesive component, and containing an isocyanate compound and a monohydric alcohol in the pressure-sensitive adhesive component. Since the pressure-sensitive adhesive composition in the present invention contains an isocyanate compound and a monohydric alcohol together with SBR and natural rubber which are pressure-sensitive adhesive components, unreacted isocyanate compounds remaining in the pressure-sensitive adhesive composition are mutually bonded. Since the pseudo-crosslinking reaction that occurs due to self-condensation is suppressed, the solution viscosity of the adhesive does not change over time, allowing stable storage for a long period of time, and also used as an adhesive for adhesive tapes In this case, excellent adhesion to the adherend is maintained without causing a reduction in the rewinding force of the adhesive tape and a decrease in the adhesive force over time.

  The pressure-sensitive adhesive composition (pressure-sensitive adhesive composition) of the present invention contains styrene-butadiene rubber (styrene-butadiene copolymer: SBR) and natural rubber as essential components for the pressure-sensitive adhesive component.

  As said SBR used by this invention, well-known thru | or usual SBR can be used, About the kind or grade of this SBR, it does not specifically limit, SBR of various grades can be used. Specifically, for example, the product name “SBR1013S” manufactured by SHELL, the product name “SBR1502” manufactured by Zeon Corporation, the product names “SBR1027”, “SBR1500”, “SBR1501”, “SBR1502” manufactured by JSR, “SBR 1503”, “SBR 1505”, “SBR 1507”, “SBR 1508”, and the like. Also, the ratio of styrene and butadiene as monomer components in SBR is not particularly limited. Conventionally, adhesive sticks to the blade at the time of punching or sticking out of the tape due to insufficient cohesive force. SBR that could not be used due to the occurrence of adhesion (deglue) of the resin can also be suitably used in the present invention. Further, the SBR may be the same grade or a mixture of different grades.

  Examples of the natural rubber used in the present invention include standard malaysian rubber (SMR), standard vietnamese rubber (SVR), rib smoked sheet (RSS) Nos. 1-6, and pale crepes Nos. 1-3. As long as it is a typical high molecular weight solid type, it is not limited to these. Further, the content ratio of SBR and natural rubber in the adhesive component is not particularly limited. For example, SBR / natural rubber = 10/90 to 90/10 (weight ratio), preferably 20/80 to 80 A range of / 20 can be selected. When the ratio of SBR / natural rubber contained in the adhesive component is less than 10/90 (weight ratio), it is difficult to obtain sufficient aging resistance. On the other hand, when the ratio is more than 90/10 (weight ratio), sufficient It becomes difficult to obtain tackiness and adhesive strength.

  In the present invention, as long as the adhesive component contains SBR and natural rubber as essential components, other adhesive components may be mixed and used in addition to the essential components. Examples of other adhesive components other than SBR and natural rubber that can be used in the present invention include polyisobutylene, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-ethylene-propylene- It is selected from synthetic rubber such as styrene copolymer, styrene-ethylene-butylene-styrene copolymer, acrylic polymer, urethane polymer, and silicone polymer. Such adhesive components other than SBR and natural rubber can be used alone or in combination of two or more. When other adhesive components are mixed with SBR and natural rubber, the content ratio of SBR is 10 to 90% by weight, preferably 20 with respect to the total amount of adhesive components (composed of SBR and natural rubber and other adhesive components). -80% by weight, more preferably 30-70% by weight. When the SBR content is less than 10% by weight, sufficient aging resistance tends to be difficult to obtain, or when it exceeds 90% by weight, the effect of mixing other adhesive components other than SBR and natural rubber is obtained. It tends to be difficult.

  Moreover, the pressure-sensitive adhesive composition in the present invention needs to contain an isocyanate compound and a monohydric alcohol together with the pressure-sensitive adhesive component.

  As the isocyanate compound, a known or conventional isocyanate crosslinking agent can be preferably used. Isocyanate compounds include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, aromatic polyisocyanate compounds, araliphatic polyisocyanate compounds, and the like. An isocyanate compound can be used individually or in combination of 2 or more types.

  Examples of the aliphatic polyisocyanate compound include 1,6-hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine. Aliphatic diisocyanate compounds such as diisocyanate are included.

  Examples of the alicyclic polyisocyanate compounds include alicyclic diisocyanate compounds such as isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate. included.

  Examples of the aromatic polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, and 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 Good compounds such as diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5'-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate Etc. family diisocyanate-based compound.

  Examples of the araliphatic polyisocyanate compound include araliphatic diisocyanate compounds such as xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate.

  In addition, as the isocyanate-based compound, the aliphatic polyisocyanate-based compound, the alicyclic polyisocyanate-based compound, the aromatic polyisocyanate-based compound, the dimer or trimer by the araliphatic polyisocyanate-based compound, the reaction Products or polymers (eg, diphenylmethane diisocyanate dimers and trimers, reaction products of trimethylolpropane and tolylene diisocyanate, reaction products of trimethylolpropane and hexamethylene diisocyanate, polymethylene polyphenyl isocyanate , Polyether polyisocyanate, polyester polyisocyanate, etc.) can also be used.

  The ratio of the isocyanate compound contained in the pressure-sensitive adhesive composition in the present invention is not particularly limited, but a crosslinking effect by addition of the isocyanate compound can be sufficiently obtained, and cohesion is not insufficient. The total amount of the pressure-sensitive adhesive components is selected from the range of 0.1 to 40 parts by weight, preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight. When the ratio of the isocyanate compound to be contained is less than 0.1 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive component, the crosslinking effect due to the addition of the isocyanate compound is hardly obtained, so the cohesive force tends to be insufficient. It is not preferable, and if it exceeds 40 parts by weight, the adhesive strength tends to decrease, which is not preferable.

  The monohydric alcohol used in the present invention may be any alcohol compound having one hydroxyl group in the molecule, and may be either chain-like or cyclic, or saturated or unsaturated. Specifically, methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, cyclopentanol, n-hexanol , Cyclohexanol, 2-propen-1-ol, 2-buten-1-ol, 2-penten-1-ol, 2-hexen-1-ol, benzyl alcohol, 3-phenyl-1-propanol, 3- Examples thereof include phenyl-2-propanol and 3-phenyl-2-propen-1-ol. In addition, these alcohols may be used independently and may use 2 or more types together.

  In addition, as the pressure-sensitive adhesive composition in the present invention, a monohydric alcohol having one or more reactive functional groups other than a hydroxyl group can be used in combination with the monohydric alcohol. Examples of reactive functional groups other than the hydroxyl group include amino groups, amide groups, alkoxy groups, ester groups, ketone groups, cyano groups, diazo groups, and formyl groups. Examples of monohydric alcohols having one or more reactive functional groups include 2-amino-ethanol, N, N-dimethyl-3-hydroxypropanecarboxamide, 1-hydroxypropanone, methyl 3-hydroxy-propionate, 3- Hydroxypropane nitrile, 3-oxopropionaldehyde, ethylene glycol monomethyl ether, hydroxydiazobenzene and the like can be mentioned.

  In addition, as the monohydric alcohol used in the present invention, even when various grades of SBR are used, the solution viscosity of the pressure-sensitive adhesive does not change over time, and can be stably stored for a long period of time. In particular, a lower monohydric alcohol is preferable. Here, the lower monohydric alcohol is a chain alcohol having 1 to 5 carbon atoms, particularly preferably a chain alcohol having 1 and 2 carbon atoms. Specific examples of the lower monohydric alcohol used in the present invention include methanol, ethanol, and vinyl alcohol.

  In addition, the ratio of the monohydric alcohol contained in the pressure-sensitive adhesive composition in the present invention is not particularly limited, but from the viewpoint of long-term storage stability of the pressure-sensitive adhesive solution, the isocyanate group-containing content of the isocyanate-based compound It is preferable to add appropriately so that the relationship between the amount (I) (mol) and the hydroxyl group content (II) (mol) of the monohydric alcohol satisfies 0.01 ≦ (I) / (II) ≦ 100. Preferably, 0.05 ≦ (I) / (II) ≦ 5, and more preferably 0.1 ≦ (I) / (II) ≦ 1. When the value of (I) / (II) is less than 0.01, the cohesive strength of the pressure-sensitive adhesive tends to be remarkably lowered, and when the value of (I) / (II) exceeds 100, a monohydric alcohol This is not preferable because the storage stability of the pressure-sensitive adhesive solution due to the addition of is not likely to be obtained.

  Further, the pressure-sensitive adhesive composition of the present invention includes various additives as necessary, for example, various stabilizers such as plasticizers, ultraviolet absorbers, antioxidants, tackifier resins, fillers, colorants, antistatic agents. Various known additives such as an agent, a foaming agent, and a surfactant may be blended. The amount of these additives used may be a normal amount applied to the pressure-sensitive adhesive.

  The pressure-sensitive adhesive solution used for the pressure-sensitive adhesive tape of the present invention is prepared by dissolving the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate. At this time, the solid content concentration of the pressure-sensitive adhesive solution is, for example, 20 to 50. % Is good.

  The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition on at least one surface of a substrate.

  In the present invention, various plastic films, paper, metal foil, woven fabric (fabric), non-woven fabric, etc. can be used as the substrate. Plastic films include low density polyethylene, ultra low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene / α-olefin copolymer, ethylene -Various polyolefin resins such as vinyl acetate copolymer, ethylene- (meth) ethyl acrylate copolymer, ethylene- (meth) methyl acrylate copolymer, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polyethylene naphthalate A film formed from a resin such as polyester resin such as phthalate, nylon, polyimide, polystyrene, polyphenylene sulfite, or the like can be used.

  Although it does not specifically limit about the thickness of the base material in this invention, For example, it is about 10-500 micrometers, Preferably it is 50-200 micrometers, More preferably, it is 70-150 micrometers. The base material may have a single layer form or a multi-layer form. Further, the substrate may be subjected to various treatments such as back treatment, antistatic treatment, undercoating treatment, and the like as necessary.

  The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention is, for example, about 5 to 500 μm, preferably about 10 to 200 μm.

  The pressure-sensitive adhesive tape in the present invention can be produced by forming a pressure-sensitive adhesive layer on at least one surface of a substrate using a conventional method such as a coating method. The pressure-sensitive adhesive layer may be protected by a release film (release liner). Moreover, this adhesive tape may have another layer (for example, intermediate | middle layer, undercoat etc.) in the range which does not impair the effect of this invention.

  Furthermore, the pressure-sensitive adhesive tape in the present invention is composed of, for example, a base material, a pressure-sensitive adhesive layer formed on one surface of the base material, and a back treatment layer formed on the other surface of the base material. And the surface of an adhesive layer can be piled up and laminated on the substrate back (for example, the surface of a back processing layer), and an adhesive layer can be protected. Moreover, at this time, it can produce as an adhesive tape (adhesive tape wound up in roll shape) which has the state or form wound up in roll shape by winding up in roll shape, and roll shape If it is not rolled up, it can be prepared as an adhesive sheet. In addition, when the back surface treatment layer is not formed on the base material, after forming an adhesive layer on one surface of the base material using a conventional method such as a coating method, the release surface of the release liner is adhesive. A pressure-sensitive adhesive tape wound up in a roll shape can be produced by laminating the layers so as to be in contact with the layers and winding up in a roll shape.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited only to these examples.

[Example 1]
(Base material)
Polyvinyl chloride (trade name “TH-1300” manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by weight, plasticizer (trade name “DOP” manufactured by Kao Corporation; dioctyl phthalate): 54 parts by weight, and stabilizer (trade name “NL-”) 175 ”(Mizusawa Chemical Co., Ltd.): 2 parts by weight were mixed to prepare a polyvinyl chloride resin composition. The polyvinyl chloride resin composition was molded at 150 ° C. using a calendar molding machine to produce a polyvinyl chloride film (referred to as “PVC film”) having a thickness of 100 μm as a substrate.

(Adhesive composition)
SBR (trade name “SBR1013S” manufactured by SHELL): 70 parts by weight, natural rubber (trade name “RSS1 grade” manufactured by Nomura Trading Co., Ltd.): 30 parts by weight, petroleum resin (trade name “Escollets 1315” manufactured by TONNEX; softening point 100 ° C.): 60 parts by weight, anti-aging agent (trade name “Irganox 1010” manufactured by Ciba Geigy; phenol-based anti-aging agent): 5 parts by weight, isocyanate compound (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) : 2 parts by weight, and monohydric alcohol (methanol: manufactured by Kishida Chemical Co., Ltd.): 1 part by weight were mixed to prepare an adhesive composition. In addition, in the isocyanate group content (I) (mol) of the isocyanate compound and the hydroxyl group content (II) (mol) of the monohydric alcohol, the value of (I) / (II) is 0.5. there were.

(Adhesive tape)
The pressure-sensitive adhesive composition obtained by the method described above was dissolved in toluene to prepare a pressure-sensitive adhesive solution having a solid concentration of 25%. Then, the adhesive solution is applied to one side of the base material not subjected to the back treatment by a comma direct coater and dried at 130 ° C. for 2 minutes to form an adhesive layer so that the thickness after drying becomes 30 μm. Then, it was wound into a roll with a winder and further cut with a cutting machine to prepare a roll-shaped adhesive tape having a width of 19 mm and a length of 20 m.

[Example 2]
A pressure-sensitive adhesive tape was obtained according to Example 1, except that the amount of monohydric alcohol (methanol) added to the pressure-sensitive adhesive composition was 2 parts by weight. In addition, in the isocyanate group content (I) (mol) of the isocyanate compound and the hydroxyl group content (II) (mol) of the monohydric alcohol, the value of (II) / (I) was 0.2. It was.

[Comparative Example 1]
A pressure-sensitive adhesive tape was obtained according to Example 1 except that the isocyanate compound and the monohydric alcohol were not added to the pressure-sensitive adhesive composition.

[Comparative Example 2]
An adhesive tape was obtained according to Example 1 except that no monohydric alcohol was added to the adhesive composition.

[Comparative Example 3]
A pressure-sensitive adhesive tape was obtained according to Example 1 except that 1 part by weight of dihydric alcohol (ethylene glycol: manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the pressure-sensitive adhesive composition instead of monohydric alcohol.

  Using the adhesive tapes obtained in Examples 1 and 2 and Comparative Examples 1 to 3, the following characteristics were evaluated. In addition, each measuring method is as showing below, and the evaluation result was shown in Table 1.

<Measurement of adhesive strength>
Each adhesive tape is cut to a width of 19 mm, and the adhesive tape is attached to a SUS stainless steel plate by reciprocating a 2 kg rubber roller, and left at room temperature (23 ° C.) and 65% RH for 30 minutes, and then a tensile test. A 180 degree peel adhesive force at a tensile speed of 300 mm / min (23 ° C.) was measured using a machine to evaluate the adhesiveness.

<Measurement of cohesive force>
Each adhesive tape was cut to a width of 25 mm to prepare a test piece, and a 2 kg rubber roller was attached to the stainless steel plate by one reciprocation so that the adhesive surface had a shape of 25 mm × 25 mm. Subsequently, after standing for 30 minutes in an atmosphere of 40 ° C., the stainless steel plate is fixed vertically, a load of 500 g is applied to one end of the test piece, the time until the load drops is measured, and the cohesive force is based on the following period. Evaluated.
Initial: After 24 hours at room temperature (25 ° C) after preparation of adhesive tape After 7 days: After storage for 7 days at room temperature (25 ° C) after preparation of adhesive tape

<Measurement of solution viscosity>
Using each adhesive solution (solid content concentration: 25%, solvent: toluene), according to JIS K-6833, using a B-type viscometer (manufactured by TOKIMEC) in an atmosphere of 30 ° C., The degree of increase in viscosity over time of the adhesive was evaluated based on the following period.
Initial: 7 days after preparation of the adhesive solution: After storage of the adhesive solution, after storage for 7 days at room temperature (25 ° C)

表１の結果より、ＳＢＲおよび天然ゴムを粘着成分の必須成分として含有し、さらにイソシアネート系化合物および一価アルコールを含有する粘着剤組成物により形成されている本発明の粘着テープは、全実施例において、いずれも被着体に対する優れた接着性を有しており、７日間の保存後であっても初期と比較して粘着テープの凝集力がほとんど変動しないという結果が得られた。また、粘着剤の溶液粘度についても、全実施例において、粘着剤の調製直後と経日後ではほとんど粘度の変化が見られず、経日での粘着剤溶液の粘度上昇を防止できることが明らかとなった。これに対して、比較例１では、イソシアネート系化合物と一価アルコールを添加しなかったために、粘着剤としての十分な凝集力が得られず、荷重が落下するまでの時間が実施例よりも短くなってしまった。次に比較例２では、一価アルコールを加えなかったため、また比較例３では、一価アルコールに代えて二価アルコールを用いたため、粘着テープ作製初期に比べると７日間経過後では、荷重が落下するまでの時間が長くなっており、粘着剤の凝集力が経日で変動してしまったことが分かると共に、粘着剤溶液の著しい粘度上昇が見られたことより、比較例で用いた粘着剤組成物は保存安定性に乏しく本発明における粘着テープの粘着剤として適さないという結果となった。

From the results shown in Table 1, the adhesive tape of the present invention, which contains SBR and natural rubber as essential components of the adhesive component, and is further formed of an adhesive composition containing an isocyanate compound and a monohydric alcohol, all the examples No. 1 had excellent adhesion to the adherend, and the cohesive force of the pressure-sensitive adhesive tape hardly changed even after storage for 7 days compared to the initial stage. In addition, regarding the solution viscosity of the pressure-sensitive adhesive, in all Examples, it is clear that there is almost no change in viscosity immediately after the preparation of the pressure-sensitive adhesive and after the lapse of time, and it is possible to prevent an increase in the viscosity of the pressure-sensitive adhesive solution over time. It was. On the other hand, in Comparative Example 1, since the isocyanate compound and the monohydric alcohol were not added, sufficient cohesive force as an adhesive could not be obtained, and the time until the load dropped was shorter than in the examples. It is had. Next, in Comparative Example 2, monohydric alcohol was not added, and in Comparative Example 3, dihydric alcohol was used instead of monohydric alcohol, so that the load dropped after 7 days compared to the initial stage of production of the adhesive tape. It was found that the time until the adhesive was long and the cohesive strength of the adhesive had fluctuated over time, and the viscosity of the adhesive solution was significantly increased. The composition had poor storage stability and resulted in being unsuitable as an adhesive for the adhesive tape in the present invention.

According to the pressure-sensitive adhesive composition of the present invention, even when various grades of SBR are used, the pot life can be maintained long without the solution viscosity of the pressure-sensitive adhesive changing over time during storage. In addition, when used as a pressure-sensitive adhesive for pressure-sensitive adhesive tapes, it suppresses an increase in cohesive strength over time, so that it maintains a good pressure-sensitive adhesive force at the initial stage of adhesion, causing a decrease in rewinding force and terminal peeling. And can be suitably used as a pressure-sensitive adhesive tape that exhibits excellent adhesive properties to adherends.

Claims (2)

Styrene as an adhesive component - containing butadiene rubber (SBR) and natural rubber as an essential component, and the adhesive component, a pressure-sensitive adhesive composition characterized by containing an isocyanate compound and monohydric alcohol The ratio of the isocyanate compound is 0.1 to 40 parts by weight with respect to 100 parts by weight of the adhesive component, and the monohydric alcohol is an isocyanate group content (I) (mol) of the isocyanate compound and the monohydric alcohol. A pressure-sensitive adhesive composition contained such that the hydroxyl group content (II) (mol) has a relationship represented by the following formula (1) .
0.01 ≦ (I) / (II) ≦ 100 (1) A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to claim 1 on at least one surface of a substrate.