JP2008207933A - Adhesive sheet for hand rail - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet for a hand rail not generating remaining of paste on the hand rail when it is peeled off the hand rail. <P>SOLUTION: In the adhesive sheet for the hand rail, an adhesive and a separator having a mold releasing property are successively laminated on a thermoplastic polyurethane film. An urethane based adhesive containing an urethane resin obtained by reacting a chain extender with an isocyanate group-terminated urethane prepolymer is used as the adhesive, and an amine compound having two active hydrogen-containing groups selected from the group consisting of a primary amino group, a secondary amino group and a primary hydroxyl group and one or more hydroxyl group having lower activity than the active hydrogen-containing group is used as the chain extender. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure sensitive adhesive sheet for handrails, and more specifically, it is used for the purpose of providing information such as advertisements and guidance display of handrails of passenger conveyors such as escalators and moving walkways, design indications, antibacterial purposes, etc. The present invention relates to an adhesive sheet for handrails.

  In general, a handrail such as a passenger conveyor has a belt shape connected endlessly. When traveling, the handrail always expands and contracts according to the curvature of the surface of the coated rubber material. For this reason, when sticking an adhesive sheet on the surface, using the synthetic resin film (polyurethane film) which can fully follow this expansion and contraction is proposed (for example, refer to patent documents 1).

By the way, in the pressure-sensitive adhesive used for the handrail pressure-sensitive adhesive sheet, generally, an acrylic pressure-sensitive adhesive that allows easy design and setting of pressure-sensitive adhesive force and removability is used. The thermoplastic resin film is preferably made of thermoplastic polyurethane because it requires its flexibility and flexibility. Moreover, in the case of a thermoplastic polyurethane film, due to its flexibility and flexibility, when applying an adhesive, the resin film is not applied directly to the film, but applied to a separator (release film) or the like. The indirect coating method for transferring to the surface has been preferably carried out conventionally. However, there is a drawback that adhesive residue is easily left on the handrail when the handrail pressure-sensitive adhesive sheet manufactured by such a conventional method is peeled off from the handrail. In particular, the defect is remarkable after attachment for a long time under low temperature such as in winter. For this reason, replacement of the handrail pressure-sensitive adhesive sheet that is frequently performed is a problem in work.
JP 2003-276975 A

  In view of such circumstances, the present invention is intended to provide a handrail pressure-sensitive adhesive sheet that does not cause adhesive residue on the handrail when peeled from the handrail.

The present inventors have obtained urethane obtained by reacting an isocyanate group-terminated urethane prepolymer with a chain extender and, if necessary, terminating the reaction with a terminal terminator, as a pressure-sensitive adhesive for a handrail pressure-sensitive adhesive sheet of a thermoplastic polyurethane film. Use a urethane-based pressure-sensitive adhesive containing a resin, and more than two active hydrogen-containing groups consisting of a primary amino group, a secondary amino group, and a primary hydroxyl group as the chain extender and the active hydrogen-containing group. The problem of the present invention is solved by using an amine compound having at least one hydroxyl group having low activity.
The pressure-sensitive adhesive sheet for handrails of the present invention is characterized by the following configuration or structure.

(1). In a pressure sensitive adhesive sheet for handrails in which at least a pressure sensitive adhesive and a releasable separator are laminated on a thermoplastic polyurethane film, the pressure sensitive adhesive is a urethane obtained by reacting an isocyanate group-terminated urethane prepolymer with a chain extender. Resin, and as the chain extender, two active hydrogen-containing groups selected from the group consisting of a primary amino group, a secondary amino group, and a primary hydroxyl group and one hydroxyl group having a lower activity than the active hydrogen-containing group A pressure-sensitive adhesive sheet for handrails, wherein an amine compound having at least one is used.

  (2). An amine compound having two primary hydroxyl groups and one or more secondary hydroxyl groups and / or tertiary hydroxyl groups; one primary amino group or one secondary amino group and primary hydroxyl groups; A group comprising: an amine compound having one and one or more secondary and / or tertiary hydroxyl groups; an amine compound having two primary amino groups and / or two secondary amino groups and one or more hydroxyl groups; The handrail pressure-sensitive adhesive sheet according to (1), wherein the pressure-sensitive adhesive sheet is one or more amine compounds selected from:

(3). Wherein the amine compound _{is, (HOC 2 H 4) 2} N (CH 2 CH (OH) CH 3), 1- _{methylamino-propanediol, (HOC 2 H 4) NH} (CH 2 CH (OH) CH 3), ( _{H 2 NCH 2 CH 2) N} (CH 2 CH 2 OH) (CH 2 CH (CH 3) OH), 1- aminopropane _{diol, (H 2 NCH 2 CH 2} ) NH (CH 2 CH (CH 3) OH _{), H 2 N-C 6} H 3 CH 3 -NH (CH 2 CH (OH) CH 3), H 2 NCH 2 -C 6 H 4 -CH 2 NH (CH 2 CH (OH) CH 3), ( _{H 2 NCH 2 CH 2) NH} (CH 2 CH 2 OH), H 2 N-C 6 H 3 CH 3 -NH (CH 2 CH 2 OH) and _{H 2 NCH 2 -C 6 H 4} -CH 2 NH ( CH ₂ CH ₂ OH) Tona Pressure-sensitive adhesive sheet of the handrail according to the above is an amine compound selected from the group (1) or (2).

(4). The adhesive sheet for handrails according to any one of (1) to (3) above, wherein the adhesive strength of the adhesive sheet according to JIS-Z-0237 test is 5 N / 25 mm or more.
(5). The handrail pressure-sensitive adhesive sheet according to any one of the above (1) to (4), wherein the content of the urethane-based pressure-sensitive adhesive in the pressure-sensitive adhesive is 70% by mass or more.
(6). The adhesive sheet for handrails according to any one of (1) to (5), wherein the separator is a polyolefin film.

  According to the pressure-sensitive adhesive sheet for handrails of the present invention, the specific urethane pressure-sensitive adhesive used above has excellent adhesion to a thermoplastic polyurethane film. For this reason, when peeling off the handrail adhesive sheet from the handrail, no adhesive residue is generated on the handrail side. Moreover, since it has an adhesive strength comparable to that of an acrylic pressure-sensitive adhesive, the handrail has a high follow-up ability to the circular movement. In addition, while the acrylic pressure-sensitive adhesive performs adhesion work by its own flow, the urethane pressure-sensitive adhesive of the present invention has a strong interfacial adhesion dependency due to high polarity, and when an adhesive sheet is stretched on the handrail, The attachment work can be performed more easily than when the adhesive is used alone. Since the urethane pressure-sensitive adhesive of the present invention does not adhere to nonpolar substances, when an acrylic pressure-sensitive adhesive is used alone, an expensive silicone separator (release sheet) must be used as the separator. In this case, an inexpensive polyolefin film can be used as a separator, and an excellent effect of having a low temperature sticking property can be obtained.

Embodiments of the present invention will be described below.
The pressure-sensitive adhesive sheet for handrails of the present invention is obtained by sequentially laminating a pressure-sensitive adhesive and a releasable separator on a thermoplastic polyurethane film.
The present invention is characterized in that a part or all of a specific urethane is used as a pressure-sensitive adhesive in a thermoplastic polyurethane film.

  As the thermoplastic polyurethane film used in the pressure-sensitive adhesive sheet for handrails of the present invention, a film known per se can be used. For example, as described in JP-A-2003-276975, it is a thermoplastic polyurethane film produced by a general film production method, and the film thickness can also be appropriately selected and used. The design surface of the thermoplastic polyurethane film can be used by laminating a metal film such as a resin film or an aluminum film containing a pigment, a dye, an antibacterial agent, or the like.

  The pressure-sensitive adhesive of the present invention may be directly applied to a thermoplastic polyurethane film and laminated, or may be applied to a separator (or a release film), and the separator may be bonded to the thermoplastic polyurethane film. In the handrail pressure-sensitive adhesive sheet of the present invention, a sheet produced by the latter method is preferable because of its workability.

The pressure-sensitive adhesive of the present invention uses a urethane-based pressure-sensitive adhesive containing a urethane resin obtained by reacting an isocyanate group-terminated urethane prepolymer with a chain extender and, if necessary, terminating the reaction with a terminal terminator. As an agent, an amine compound having two active hydrogen-containing groups selected from the group consisting of a primary amino group, a secondary amino group, and a primary hydroxyl group, and one or more hydroxyl groups that are less active than the active hydrogen-containing group It is characterized by using.
As described above, such urethane-based pressure-sensitive adhesives may be used alone, or other pressure-sensitive adhesives, for example, acrylic pressure-sensitive adhesives may be added to a part as necessary. The proportion of the urethane pressure-sensitive adhesive in the pressure-sensitive adhesive is at least 70% by mass, preferably 85% by mass or more. Note that the acrylic pressure-sensitive adhesive to be mixed is usually a solvent-based pressure-sensitive adhesive, so a solvent-based type is selected, and a water-based emulsion type is not preferred.

In the production of the urethane resin of the present invention, an isocyanate group-terminated prepolymer is produced by reacting a polyol and a polyisocyanate compound (hereinafter referred to as a first polyisocyanate compound) in an excess ratio of isocyanate groups (prepolymer formation). Reaction), a chain extender is reacted with the isocyanate group-terminated prepolymer (chain extension reaction), and a terminal terminator is further reacted as necessary (termination reaction) to obtain a urethane resin.
Here, the pressure-sensitive adhesive of the present invention contains the obtained urethane resin, and since it has pressure-sensitive adhesive performance by itself, it can be used as it is as a pressure-sensitive adhesive, but is crosslinked by the second polyisocyanate compound. By doing so, it can also be used as a pressure-sensitive adhesive to which a so-called crosslinking agent is added. In this case, the pressure-sensitive adhesive is preferably a pressure-sensitive adhesive containing a crosslinked urethane resin obtained by reacting a hydroxyl group remaining in the urethane resin with a second polyisocyanate compound that functions as a crosslinking agent.
Below, the raw material used for an adhesive, a synthetic raw material, etc. are explained in full detail.

(Isocyanate group-terminated urethane prepolymer)
The isocyanate group-terminated urethane prepolymer is an isocyanate group-terminated urethane prepolymer obtained by reacting a polyol and a first polyisocyanate compound in an excess ratio of isocyanate groups.
Examples of the polyol include polyoxyalkylene polyol, polyester polyol, polyoxytetramethylene glycol, and polycarbonate polyol. Among the polyols, polyoxyalkylene polyols are preferable for obtaining flexibility.
The polyoxyalkylene polyol is a ring-opening polymerization catalyst such as an alkali metal compound catalyst (for example, potassium hydroxide, cesium hydroxide, etc.); and in the presence of a polyvalent initiator such as a polyhydric alcohol; ethylene oxide, propylene oxide, etc. It can be produced by ring-opening addition of alkylene oxide.
The valence (number of active hydrogen atoms) of the polyvalent initiator is preferably 2 to 6, more preferably 2 to 3, and most preferably 2. Examples of the divalent initiator include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, and bisphenol A.
Moreover, it is preferable that the hydroxyl value of a polyoxyalkylene polyol is 5.6-600 mgKOH / g. When the hydroxyl value is less than 5.6 mg KOH / g, the molecular weight is large, so that it is difficult to react with the polyisocyanate compound, and the resulting prepolymer tends to be difficult to react with the chain extender. On the other hand, when the hydroxyl value exceeds 600 mgKOH / g, the ratio of the isocyanate compound in the prepolymer obtained is relatively high, and gelation is likely to occur when the isocyanate group-terminated prepolymer is reacted with the chain extension.
The hydroxyl value of the polyoxyalkylene polyol can be appropriately selected from the above range depending on the adhesive strength of the adhesive to be finally obtained. When obtaining an adhesive having an adhesive strength of 5 N / 25 mm or more, the hydroxyl value is preferably 5.6 to 450 mgKOH / g, more preferably 11 to 280 mgKOH / g, and most preferably 18 to 160 mgKOH / g. .

A known aromatic polyisocyanate aliphatic polyisocyanate can be used as the first polyisocyanate compound. Examples of the aromatic polyisocyanate include polyisocyanates having an aromatic ring and having an isocyanate group directly bonded to the aromatic ring. For example, 1,3- or 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate (hereinafter referred to as MDI) 2,4- or 2,6-tolylene diisocyanate (hereinafter referred to as TDI), etc. Is mentioned. Moreover, the polyisocyanate which has an aromatic ring and has an isocyanate group which is not couple | bonded directly with this aromatic ring is mentioned. Examples thereof include p- or m-tetramethylxylylene diisocyanate (C ₆ H ₄ [C (CH ₃ ) ₂ NCO] ₂ ) (hereinafter referred to as TMXDI).
Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter referred to as HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3. -Butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate and the like.
Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (hereinafter referred to as IPDI) 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1 , 4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane, 1, 4-bis (isocyanatomethyl) cyclohexane norbornene diisocyanate and the like.
Further, it may be a trimethylolpropane adduct type modified product of polyisocyanate described above, a burette type modified product reacted with water, or an isocyanate type modified product containing an isocyanate ring. Among the polyisocyanates described above, one or more selected from HDI, PDI, MDLTDI, TMXDI, and modified products thereof are preferable.

The prepolymer generation reaction is not particularly limited, and examples thereof include performing the above polyol, the first polyisocyanate compound, and, if necessary, a urethanization catalyst and a solvent in a reactor.
As an aspect of the present invention, in order to obtain an isocyanate group-terminated prepolymer, a polyol and a polyisocyanate compound are reacted in an excess ratio of an isocyanate group. The blending ratio (reaction ratio) of the polyol and the first polyisocyanate compound is such that the index ((number of moles of NCO) / (number of moles of OH) × 100) is 110 so that isocyanate groups remain at the ends. It is preferable to make it react so that it may become -300, and it is more preferable to make it react so that it may become 130-250. If the index is less than 110, gelation tends to increase the viscosity, and if it exceeds 300, the unreacted isocyanate compound concentration in the prepolymer becomes too high and the next chain extension reaction tends to be difficult.
The isocyanate group content (NCO%) of the isocyanate group-terminated prepolymer is preferably 0.5 to 12% by mass, although it varies depending on the reactivity of the compound used and the amount of the chain extender described later. The mass% is more preferable. If the NCO% is less than 0.5% by mass, a sufficient amount of chain extender cannot be reacted, and if it exceeds 12% by mass, the chain extension reaction tends to be difficult to control.

Examples of the urethanization catalyst used in the prepolymer formation reaction include triethylamine, triethylenediamine, N, N-dimethylbenzylamine, N-methylmorpholine, 1,8-diazabicyclo [5.4.0] undecene-7 ( And the like, and known compounds such as tertiary amine compounds such as DBU) and organometallic compounds such as dibutyltin dilaurate (hereinafter referred to as DBTDL) and tin 2-ethylhexanoate.
Also. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone (MEK), dimethylformamide, and cyclohexanone.
The reaction temperature is preferably 120 ° C. or lower, more preferably 70 to 100 ° C. If the reaction temperature is 120 ° C. or lower, it is possible to easily synthesize an isocyanate group-terminated prepolymer having a predetermined molecular weight and structure by suppressing the progress of the allophanate reaction, and to easily control the reaction rate.

(Urethane resin)
A specific amine compound is used for the chain extender used in the urethane prepolymer. That is, in the present invention, as the chain extender, two active hydrogen-containing groups selected from the group consisting of a primary amino group, a secondary amino group, and a primary hydroxyl group are more active than the active hydrogen-containing group. An amine compound having at least one low hydroxyl group is used.
By using a specific amine compound, it is possible to obtain a urethane-based pressure-sensitive adhesive with little adhesive residue and excellent adhesive properties for use in a handrail.

  The specific amine compound has two active hydrogen-containing groups having high comparative reactivity and one or more hydroxyl groups having lower activity. Specifically, the amine compound has two primary hydroxyl groups and an amine compound having one or more secondary hydroxyl groups and / or tertiary hydroxyl groups; one primary amino group or one secondary amino group; An amine compound having one primary hydroxyl group and one or more secondary and / or tertiary hydroxyl groups; an amine compound having two primary amino groups and / or two secondary amino groups and one or more hydroxyl groups Is selected from the group consisting of;

More specifically, as an amine compound having two primary hydroxyl groups and one or more secondary hydroxyl groups and / or tertiary hydroxyl groups, N, N-bis (2-hydroxyethyl) -N- ( 2-hydroxypropyl) amine ((HOC ₂ H ₄ ) ₂ N (CH ₂ CH (OH) CH ₃ ); a compound obtained by adding propylene oxide to diethanolamine) and the like.
Examples of amine compounds having one primary amino group or secondary amino group, one primary hydroxyl group, and one or more secondary and / or tertiary hydroxyl groups include 1-methylaminopropanediol (CH _{3 NH (CH 2 CH (OH} ) CH 2 OH)), N- (2- hydroxypropyl) ethanolamine _{((HOC 2 H 4) NH} (CH 2 CH (OH) CH 3): propylene oxide to monoethanolamine And the like, (H ₂ NCH ₂ CH ₂ ) N (CH ₂ CH ₂ OH) (CH ₂ CH (CH ₃ ) OH), 1-aminopropanediol and the like.
As an amine compound having two primary amino groups and / or two secondary amino groups and one or more hydroxyl groups, (H ₂ NCH ₂ CH ₂ ) NH (CH ₂ CH (CH ₃ ) OH): ethylenediamine and propylene compounds obtained by adding _{oxides, H 2 N-C 6 H} 3 CH 3 -NH (CH 2 CH (OH) CH 3): compound obtained by adding propylene oxide to tolylenediamine, N-(2-hydroxy-propyl) Metaxylylenediamine (H ₂ NCH ₂ —C ₆ H ₄ CH ₂ —NH (CH ₂ CH (OH) CH ₃ ): Compound obtained by adding propylene oxide to xylylenediamine), (H ₂ NCH ₂ CH ₂ ) _{NH (CH 2 CH 2 OH)} : a compound obtained by adding ethylene oxide to _{ethylenediamine, H 2 N-C 6 H} 3 CH 3 -NH ( H ₂ CH ₂ OH): a compound obtained by adding ethylene oxide to _{tolylenediamine, H 2 NCH 2 -C 6 H} 4 -CH 2 NH (CH 2 CH 2 OH): a compound obtained by adding ethylene oxide to xylylenediamine, (CH ₃ NHCH ₂ CH ₂ ) NH (CH ₂ CH (CH ₃ ) OH), (CH ₃ NHCH ₂ CH ₂ ) NH (CH ₂ CH ₂ OH), (H ₂ NCH ₂ CH ₂ ) ₂ N (CH ₂ CH (CH ₃ ) OH), (H ₂ NCH ₂ CH ₂ ) ₂ N (CH ₂ CH ₂ OH) and the like. As an amine compound having two primary amino groups and / or secondary amino groups and one or more hydroxyl groups, one primary amino group, one secondary amino group, and one or more hydroxyl groups The amine compound which has is more preferable.

Among these specific amine _{compound, (HOC 2 H 4) 2} N (CH 2 CH (OH) CH 3), methylamino _{propanediol, (HOC 2 H 4) NH} (CH 2 CH (OH) CH 3) _{, (H 2 NCH 2 CH 2} ) N (CH 2 CH 2 OH) (CH 2 CH (CH 3) OH), 1- aminopropane _{diol, (H 2 NCH 2 CH 2} ) NH (CH 2 CH (CH 3 _{) OH), H 2 N-} C 6 H 3 CH 3 -NH (CH 2 CH (OH) CH 3), H 2 NCH 2 -C 6 H 4 -CH 2 NH (CH 2 CH (OH) CH 3) _{, (H 2 NCH 2 CH 2} ) NH (CH 2 CH 2 OH), H 2 N-C 6 H 3 CH 3 -NH (CH 2 CH 2 OH) and _{H 2 NCH 2 -C 6 H 4} -CH 2 NH _(CH 2 CH 2 O Amine compound selected from the group consisting of) the quality of availability is relatively easy and the chain extension reaction can be obtained easily control the adhesive is particularly preferred from the stable easily like.
In the present invention, other chain extenders other than those described above may be used in combination. In particular. Examples thereof include diamine compounds such as isophorone diamine and ethylene diamine, diol compounds such as 1.4-butanediol, 1,6-hexanediol and ethylene glycol, and alkanolamines such as monoethanolamine. The other chain extender is preferably 50 mol% or less, more preferably 20 mol% or less, based on the total chain extender.

In the present invention, the method of chain extension reaction is not particularly limited. For example, 1) A method in which an isocyanate group-terminated prepolymer solution is charged into a reaction vessel, and a chain extender is dropped into the reaction vessel to cause a reaction. 2) A chain extender is charged in a reaction vessel, and an isocyanate group-terminated prepolymer solution is dropped. And 3) a method in which the isocyanate group-terminated prepolymer solution is diluted with a solvent, and then a predetermined amount of a chain extender is charged into the reaction vessel and reacted. Among 1) to 3), the isocyanate group is gradually reduced, and a uniform resin can be easily obtained. Therefore, the method 1) or 3) is preferable.
The addition amount of the chain extender varies depending on the isocyanate group content (NCO%: mass%) of the isocyanate group-terminated prepolymer, but the NCO% of the isocyanate group-terminated prepolymer after chain extension is 0.01 to 1.0%. It is preferable that it is the quantity used as 0.05-O. The amount is more preferably 2%. When the amount of the chain extender added is such that the NCO% of the isocyanate group-terminated prepolymer is 0.01% or more, it is possible to further prevent gelation due to rapid thickening during the chain extension reaction. When the NCO% of the isocyanate group-terminated prepolymer is 1.0% or less, the chain extension reaction proceeds sufficiently to facilitate obtaining the desired molecular weight.
Moreover, since gelation hardly occurs when the chain extender used in the present invention is used, an excess chain extender can be added in advance to the isocyanate group of the isocyanate group-terminated prepolymer. If the addition amount of the chain extender is excessive with respect to the isocyanate group of the isocyanate group-terminated prepolymer, the terminal of the resulting urethane resin can be made into a hydroxyl group.
The reaction temperature in the chain extension reaction is preferably 80 ° C. or lower. When the reaction temperature exceeds 80 ° C., the reaction rate becomes too fast and it becomes difficult to control the reaction, so that it tends to be difficult to obtain a urethane resin having a desired molecular weight and structure. When the chain extension reaction is carried out in the presence of a solvent, the boiling point is preferably not higher than the boiling point of the solvent, and particularly 40 to 60 ° C. in the presence of MEK and ethyl acetate.

In the present invention, when the above urethane resin is obtained, in order to control physical properties such as molecular weight, it is preferable to carry out a termination reaction with a terminal terminator as necessary. As the terminator, a compound having a functional group capable of reacting with an isocyanate group and having only one functional group, or a compound having a functional group capable of reacting with an isocyanate group, A compound having a highly reactive functional group and one functional group that is less reactive than the functional group can be used.
As a compound having only one functional group, that is, a primary amino group, a secondary amino group,
A compound having only one primary hydroxyl group or secondary hydroxyl group can be used. Examples thereof include monoamine compounds such as diethylamine and morpholine and monool compounds such as methanol.
As a compound having a functional group capable of reacting with an isocyanate group and having one functional group having a high reactivity and one functional group having a reactivity lower than the functional group, for example, one 1 The compound which has one hydroxyl group with a secondary amino group or a secondary amino group is mentioned. Specifically, a monoamine compound having a hydroxyl group such as 2-amino-2-methyl-1-propanol (hereinafter referred to as “AMP”) monoisopropanolamine, aminopropanol, or the like can be used.
A terminal terminator can be used as needed. The end-stopper reaction can be carried out in a solvent. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone (MEK), dimethylformamide, and cyclohexanone. The addition amount of the terminal stopper is preferably such that the terminal stopper is 1 to 2 moles with respect to 1 mole of the terminal isocyanate group remaining after the chain extension reaction. If the addition amount of the terminal stopper is less than 1 mole relative to 1 mole of the terminal isocyanate group remaining after the chain extension reaction, the resulting urethane resin tends to be unstable because the isocyanate group remains after the termination reaction. . On the other hand, when the addition amount of the terminal terminator exceeds 2 mol with respect to 1 mol of the terminal isocyanate group remaining after the chain extension reaction, the low molecular weight compound tends to increase.
When the terminal of the urethane resin is a hydroxyl group, it is not necessary to use a terminal terminator. The number average molecular weight of the urethane resin thus obtained is preferably 10,000 or more in terms of standard polystyrene equivalent molecular weight by GPC.

In addition, other resins such as an acrylic resin, a polyester resin, an amino resin, and an epoxy resin can be used in combination with the urethane resin as necessary. Moreover, you may add an additive. Examples of the additive include fillers such as talc, calcium carbonate, and titanium oxide, tackifiers, colorants, ultraviolet absorbers, antioxidants, antifoaming agents, and light stabilizers.
The production of the urethane resin described above is a method of reacting an isocyanate group-terminated prepolymer with a specific chain extender. For this reason, control of chain extension reaction is easy, and it has the characteristics that gelation of the urethane resin obtained can be suppressed and viscosity increase can be prevented.
Furthermore, since the urethane resin can be crosslinked using the functional group remaining in the urethane resin, it is considered that a urethane resin-based pressure-sensitive adhesive having excellent removability can be obtained by using this urethane resin as a raw material. Furthermore, since it is possible to use an easily available chain extender, the cost is low.

When using a polyurethane resin as an adhesive, it is preferable to add the second polyisocyanate (crosslinking agent) as described above.
Examples of the second polyisocyanate compound that functions as a crosslinking agent include polyfunctional polyisocyanates such as the first polyisocyanate compound and trimethylolpropane adduct-type modified products, burette-type modified products, and isocyanurate-type modified products thereof. Is used. Among the crosslinking agents, a modified product having an average functional group number exceeding 2 is preferable. For example, Duranate P301-75E (manufactured by Asahi Kasei Corporation, trimethylolpropane adduct type HDI, isocyanate group content: 12.9% by mass, solid content: 75% by mass), coronate L (manufactured by Nippon Polyurethane Co., Ltd., trimethylolpropane adduct type TDI) , Isocyanate group content: 13.5 mass%, solid content: 75 mass%) and the like can be used.
Similarly to the first polyisocyanate compound, the second polyisocyanate compound also has an aliphatic polyisocyanate alicyclic polyisocyanate excellent in weather resistance and light resistance and an aromatic ring for optical use. One or more polyisocyanates selected from the group consisting of polyisocyanates having isocyanate groups that are not directly bonded to the ring are preferred.
The second polyisocyanate compound is preferably reacted with NCO% (excluding the solvent in the case of a solution) of 10 to 30% by mass within a range of 20 parts by mass or less with respect to 100 parts by mass of the urethane resin. Since the better removability is exhibited, the reaction amount of the second polyisocyanate compound is more preferably 0.01 to 10 parts by mass. On the other hand, when the second polyisocyanate compound is not used, the cohesive force is lowered and the cohesive failure is easily caused. When the amount exceeds 20 parts by mass, the cohesive strength is too strong and the adhesive force tends to be reduced.
When the crosslinking agent and the hydroxyl group remaining in the urethane resin are reacted, a urethanization catalyst can be used. As the urethanization catalyst, a urethanization catalyst used in the prepolymer formation reaction can be used.

  The separator for the pressure-sensitive adhesive tape for handrails of the present invention is preferably a polyolefin film such as polyethylene or polypropylene, and a paper laminate film thereof. Of course, a silicone separator can also be used without problems.

Examples of the present invention will be specifically described below, but the examples do not limit the present invention.
(Manufacture of urethane adhesive)
1) Raw material and viscosity measurement Polyol: Polyoxypropylene diol having a hydroxyl value of 56.1 mgKOH / g, produced by reacting propylene oxide with propylene glycol as an initiator and using a potassium hydroxide catalyst.
Chain extender C1: N- (2-hydroxypropyl) ethanolamine.
Chain extender C2: N- (2-hydroxypropyl) metaxylylenediamine.
Chain extender C3: N, N-bis (2-hydroxyethyl) -N- (2-hydroxypropyl) amine.
The viscosity of the polyurethane solution at 25 ° C. was measured with a B-type viscometer. The number average molecular weight of the resin component in the polyurethane solution was measured in terms of polystyrene by gel permeation chromatography.

2) Synthesis example (production of urethane resin)
(Synthesis Example 1)
107 g of polyol, 18.6 g of 2,4-TDI: tolylene diisocyanate (trade name Coronate, manufactured by Nippon Polyurethane Industry Co., Ltd.) in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel T-100), DBTDL: dibutyltin dilaurate as a urethanization catalyst was charged in an amount corresponding to 25 ppm with respect to the total amount of polyol and T-100, and the temperature was gradually raised to 80 ° C. This was carried out for a time to obtain an isocyanate group-terminated prepolymer.
After cooling to 60 ° C. and adding 66 g of ethyl acetate and 66 g of MEK, 6 g of chain extender C1 was added and reacted. The reaction was continued at 60 ° C., and when the NCO% became 0.1% by mass or less, 0.4 g of MIPA: monoisopropanolamine as a terminal stopper was added to terminate the reaction. The obtained polyurethane solution A was colorless and transparent and had a solid content of 50% by mass. The viscosity of the polyurethane solution was measured and found to be 4000 mPa · s / 25 ° C. The number average molecular weight of the resin in this polyurethane solution was 90,000.
Next, Coronate L (manufactured by Nippon Polyurethane Co., Ltd., trimethylolpropane adduct type TDI, isocyanate group content: 13.5% by mass, solid content: 75% by mass) is used as a crosslinking agent for 100 g of the obtained polyurethane solution A. 1.6 g was added and stirred and mixed at 40 rpm for 1 minute to obtain a urethane resin pressure-sensitive adhesive AP.
(Synthesis Examples 2 and 3)
With the formulation shown in Table 1 below, polyurethane solutions B and C and urethane resin adhesives BP and CP were obtained in the same manner as in Synthesis Example 1 under other conditions. The following evaluation was performed for each pressure-sensitive adhesive. The results are shown in Table 1.

(Evaluation)
Apply urethane resin adhesives AP to CP to a PET film with a thickness of 75 μm so that the film thickness after drying is 25 μm, and then dry at 100 ° C. for 1 minute in a circulation oven. Obtained. And it cured for 7 days at 23 degreeC and 50-65% of relative humidity, and measured the following physical property.
[Adhesive strength]: In accordance with JIS-Z-0237, the adhesive sheet was attached to a 1.5 mm thick stainless steel plate (SUS304 (JIS)) at room temperature, pressure-bonded with a 2 kg rubber roll, and pulled after 30 minutes. Using a testing machine, the peel strength (180 degree peel, tensile speed 300 mm / min) was measured.
[Ball tack]: Measured under the conditions of 23 ° C. and 65% relative humidity by the ball tack method defined in JIS-Z-0237.
[Removability]: After sticking the adhesive sheet to a stainless steel plate (SUS304 (JIS)), the adhesive sheet was peeled off after being left under conditions of 23 ° C. and 65% relative humidity, and the adhesive residue was visually evaluated. In the visual evaluation, the case where there was no glue transfer to the stainless steel plate was evaluated as ◯, the case where there was a partial transition was evaluated as Δ, and the case where it was completely transferred was evaluated as X.

(Manufacture of adhesive sheet for handrail)
The pressure-sensitive adhesive shown in Table 2 was applied to a white thermoplastic ester polyurethane film having a thickness of 0.1 mm so as to have a thickness of 23 μm, and a polypropylene separator was laminated on the pressure-sensitive adhesive surface to prepare a pressure-sensitive adhesive sheet for handrails. . As the acrylic adhesive, Soken Chemical Co., Ltd. SK1717 was used.
The obtained pressure-sensitive adhesive sheet is affixed to a handrail made of chlorosulfonated polyethylene at room temperature and 5 ° C, left in an environment of room temperature and 5 ° C, and peeled off from the handrail under each processing condition one month later. Then, the presence or absence of each adhesive residue was observed.
The evaluation of the adhesive residue test in Table 2 is based on visual observation. The case where there is no adhesive residue on the surface of the handrail is indicated by ◯, the portion which is partly indicated by Δ, and the case where the adhesive remains completely is indicated by ×. The results are shown in Table 2.

  In addition, the adhesive sheet for handrails of this invention is not limited to above-described embodiment, Of course, various changes can be added within the range which does not deviate from the summary of this invention.

  The pressure-sensitive adhesive sheet for handrails according to the present invention is highly industrially applicable, in which a specific polyurethane resin is used as a pressure-sensitive adhesive and no adhesive residue is generated on the handrail when peeled off from the handrail.

Claims (6)

In the pressure-sensitive adhesive sheet for handrails, in which at least a pressure-sensitive adhesive and a releasable separator are laminated on the thermoplastic polyurethane film,
The pressure-sensitive adhesive includes a urethane resin obtained by reacting an isocyanate group-terminated urethane prepolymer with a chain extender, and the chain extender is selected from the group consisting of a primary amino group, a secondary amino group, and a primary hydroxyl group. An amine compound having two active hydrogen-containing groups and one or more hydroxyl groups having lower activity than the active hydrogen-containing group is used.   An amine compound having two primary hydroxyl groups and one or more secondary hydroxyl groups and / or tertiary hydroxyl groups; one primary amino group or one secondary amino group and primary hydroxyl groups; A group comprising: an amine compound having one and one or more secondary and / or tertiary hydroxyl groups; an amine compound having two primary amino groups and / or two secondary amino groups and one or more hydroxyl groups; The pressure-sensitive adhesive sheet for handrails according to claim 1, wherein the pressure-sensitive adhesive sheet is one or more amine compounds selected from the group consisting of: Wherein the amine compound _{is, (HOC 2 H 4) 2} N (CH 2 CH (OH) CH 3), 1- _{methylamino-propanediol, (HOC 2 H 4) NH} (CH 2 CH (OH) CH 3), ( _{H 2 NCH 2 CH 2) N} (CH 2 CH 2 OH) (CH 2 CH (CH 3) OH), 1- aminopropane _{diol, (H 2 NCH 2 CH 2} ) NH (CH 2 CH (CH 3) OH _{), H 2 N-C 6} H 3 CH 3 -NH (CH 2 CH (OH) CH 3), H 2 NCH 2 -C 6 H 4 -CH 2 NH (CH 2 CH (OH) CH 3), ( _{H 2 NCH 2 CH 2) NH} (CH 2 CH 2 OH), H 2 N-C 6 H 3 CH 3 -NH (CH 2 CH 2 OH) and _{H 2 NCH 2 -C 6 H 4} -CH 2 NH ( CH ₂ CH ₂ OH) Tona Pressure-sensitive adhesive sheet of the handrail according to claim 1 or 2 which is an amine compound selected from the group.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive strength according to JIS-Z-0237 of 5 N / 25 mm or more.   The content of the urethane type adhesive in an adhesive is 70 mass% or more, The adhesive sheet for handrails in any one of Claims 1-4.   The pressure-sensitive adhesive sheet for handrails according to any one of claims 1 to 5, wherein the separator is a polyolefin film.