KR102155941B1 - Surface protective pressure sensitive adhesive and pressure sensitive adhesive sheet - Google Patents

Abstract

[Problem] The present invention has good wettability to an adherend, and when affixed to a curved surface, floating and peeling are difficult to occur, re-peelability is possible, and a pressure-sensitive adhesive for surface protection and a pressure-sensitive adhesive sheet for producing a pressure-sensitive adhesive sheet having good productivity It is for the purpose of providing. [Solution means] To 100 parts by mass of the urethane urea resin (A), which is a reaction product of an isocyanate group-containing urethane prepolymer (a) and an amine compound (b), contains more than 3 parts by mass and 20 parts by mass or less of an isocyanate curing agent (B). , The urethane urea resin (A) has a molecular weight dispersion of 1.5 to 6, a pressure-sensitive adhesive for surface protection.

Description

Surface protection adhesive and adhesive sheet {SURFACE PROTECTIVE PRESSURE SENSITIVE ADHESIVE AND PRESSURE SENSITIVE ADHESIVE SHEET}

The present invention relates to an adhesive for surface protection and an adhesive sheet.

Conventionally, surface protection sheets have been used to prevent damage to various members. In forming the pressure-sensitive adhesive layer of the surface protective sheet, a pressure-sensitive adhesive containing an acrylic resin or a urethane resin is often used. Among them, a pressure-sensitive adhesive containing a urethane resin (hereinafter, referred to as a urethane pressure-sensitive adhesive) is used for surface protection applications of displays such as liquid crystal displays because it has adequate adhesion and re-peelability with respect to glass.

For example, Patent Document 1 discloses a pressure-sensitive adhesive containing at least one compound selected from a urethane resin, an isocyanate curing agent, and a polyalkylene glycol compound, an epoxy compound, and a phosphoric acid ester compound.

In addition, as a pressure-sensitive adhesive using a urethane urea resin having high adhesive strength, Patent Document 2 discloses a pressure-sensitive adhesive containing a trivalent or higher polyol, a polyisocyanate, and a urethane urea resin obtained by reacting a monoaminopolyol, and an isocyanate curing agent.

In addition, Patent Document 3 discloses a pressure-sensitive adhesive containing a urethane urea resin in which a chain extender and a terminal terminator are reacted with an isocyanate group terminal prepolymer obtained by reacting a polyol and a polyisocyanate compound, and an isocyanate curing agent.

(Patent Document 1) Japanese Patent Application Laid-Open No. 2015-7226 (Patent Document 2) Japanese Patent Laid-Open No. 2007-023117 (Patent Document 3) Japanese Patent Laid-Open No. 2006-12692

However, since the pressure-sensitive adhesive of Patent Document 1 has low adhesive strength, for example, when protecting the surface of a display having a curved portion, there is a problem that the pressure-sensitive adhesive sheet floats or peels from the curved portion.

In addition, since the pressure-sensitive adhesive of Patent Document 2 has a three-dimensional structure with many branches of urethane urea resin, the cohesive force of the pressure-sensitive adhesive layer was excessive when the pressure-sensitive adhesive was processed on the surface protection sheet. Therefore, when the surface protection sheet is affixed to a curved surface, there is a problem in that it floats.

In addition, the pressure-sensitive adhesive of Patent Document 3 takes a curing time with an isocyanate curing agent because the hydroxyl group formed from the reaction of the isocyanate group terminal prepolymer and the chain extender has a secondary hydroxyl group, and until the pressure-sensitive adhesive sheet is used for surface protection purposes. It took time and there was a problem of productivity.

The present invention provides a pressure-sensitive adhesive for surface protection and a pressure-sensitive adhesive sheet for producing a pressure-sensitive adhesive sheet having good wettability to an adherend, hardly causing floating and peeling when affixed to a curved surface, re-peelable, and good productivity. The purpose.

The pressure-sensitive adhesive for surface protection of the present invention exceeds 3 parts by mass of the isocyanate curing agent (B) and 20 parts by mass of 100 parts by mass of the urethane urea resin (A), which is a reaction product of an isocyanate group-containing urethane prepolymer (a) and an amine compound (b). It contains not more than a mass part, and the molecular weight dispersion degree of the said urethane urea resin (A) is 1.5-6.

According to the present invention, a pressure-sensitive adhesive for surface protection and a pressure-sensitive adhesive sheet are provided for producing a pressure-sensitive adhesive sheet having good wettability to an adherend, hardly causing floating and peeling when affixed to a curved surface, re-peelable, and good productivity. can do.

Terms are defined before describing the present invention. In this specification, the adherend refers to an object to which the adhesive tape is affixed. In the present specification, the molecular weight dispersion degree is a value obtained by dividing the weight average molecular weight by the number average molecular weight, and is a standard for molecular weight distribution.

In the present specification, productivity means that when the pressure-sensitive adhesive is coated, the cohesive force of the pressure-sensitive adhesive layer is rapidly expressed (because crosslinking proceeds with a small amount of heat), so that the coating speed can be increased and the productivity of the pressure-sensitive adhesive sheet is improved.

In the present specification, the pressure-sensitive adhesive sheet includes an adhesive layer comprising a substrate and a cured product of the pressure-sensitive adhesive of the present invention.

In the present specification, "tape", "film", and "sheet" have the same meaning.

In the present specification, the main component refers to a component with the largest amount of compounding among a plurality of components.

In this specification, unless otherwise specified, "molecular weight" shall mean a number average molecular weight (Mn). In addition, "Mn" is a number average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC) measurement.

The pressure-sensitive adhesive of the present invention contains an isocyanate curing agent (B) in excess of 3 parts by mass and 20 parts by mass or less with respect to 100 parts by mass of a urethane urea resin (A), which is a reaction product of an isocyanate group-containing urethane prepolymer (a) and an amine compound (b). It contains, and the molecular weight dispersion degree of the said urethane urea resin (A) is 1.5-6, and it is preferable to use it for surface protection use.

The pressure-sensitive adhesive for surface protection of the present invention contains an appropriate amount of an isocyanate curing agent (B) with respect to the urethane urea resin (A) having a relatively narrow molecular weight dispersion degree. Since the surface protection sheet using this pressure-sensitive adhesive for surface protection has an appropriate adhesive force and cohesive force, floating or peeling is difficult to occur because the flat portion is sufficiently adhered to the original curved portion, and peeling if necessary (also referred to as re-peel) I can).

The pressure-sensitive adhesive for surface protection of the present invention can be used for, for example, a display such as a liquid crystal display (LCD) having a flat portion or a curved portion, an organic electroluminescent display (ELD), and a touch panel using a related display. In addition, it can be widely used for surface protection of electronic devices such as mobile phones, smart phones, portable terminals of tablet terminals, and computers equipped with such displays or touch panels.

In addition, the surface protection is not limited to glass, and can be used to protect materials that are easily damaged such as polyolefin, gold, silver, copper, and ITO.

In addition, the use of surface protection is not limited to a display, and can be used for protection of all surfaces such as window glass, LED, vehicle, and wiring. In addition, surface protection can be used for protection during the manufacturing process of the member and for surface protection after manufacturing. In addition, it goes without saying that the pressure-sensitive adhesive for surface protection of the present invention can be used other than for surface protection.

(Urethane Urea Resin (A))

The urethane urea resin (A) is a reaction product obtained by reacting a urethane prepolymer containing at least one isocyanate group and at least one amine compound by a urea reaction (a urea bond is formed). The urea reaction can be carried out in the presence of a catalyst, if necessary. A solvent can be used for the copolymerization reaction, if necessary. Moreover, as for the urethane urea resin (A), it is independent or can use 2 or more types.

<Isocyanate Group-Containing Urethane Prepolymer (a)>

The urethane prepolymer (a) containing an isocyanate group is preferably a compound synthesized by urethane reaction (formation of a urethane bond) of polyisocyanate (x) and polyol (y). Further, as for the polyisocyanate (x), a bifunctional isocyanate (x1) having two isocyanate groups in one molecule is preferable. Further, the polyol (y) is preferably a bifunctional polyol (y1) having two hydroxyl groups in one molecule. The isocyanate group of the polyisocyanate (x) is used in a molar ratio that becomes excessive than the hydroxyl group of the polyol (y).

In the urethane reaction, it is preferable to use a catalyst for accelerating the reaction.

<Polyisocyanate (x)>

As the polyisocyanate compound (x), known compounds such as aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, and alicyclic polyisocyanate can be used, for example.

The aromatic polyisocyanate is, for example, 1, 3-phenylene diisocyanate, 4, 4'-diphenyl diisocyanate, 1, 4-phenylene diisocyanate, 4, 4'-diphenylmethane diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4, 4'-toluidine diisocyanate, 2, 4, 6-triisocyanate toluene, 1, 3, 5-triisocyanate benzene, dianicidine diisocyanate , 4, 4'-diphenyl ether diisocyanate, and 4, 4', 4"-triphenylmethane triisocyanate, and the like.

Aliphatic polyisocyanates are, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3- Butylene diisocyanate, dodecamethylene diisocyanate, and 2, 4, 4-trimethylhexamethylene diisocyanate, and the like.

The aromatic aliphatic polyisocyanate is, for example, ω,ω'-diisocyanate-1, 3-dimethylbenzene, ω,ω'-diisocyanate-1, 4-dimethylbenzene, ω,ω'-diisocyanate-1, 4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate, etc. are mentioned.

Alicyclic polyisocyanates are, for example, 3-isocyanate methyl-3, 5, 5-trimethylcyclohexyl isocyanate, 1, 3-cyclopentane diisocyanate, 1, 3-cyclohexane diisocyanate, and 1, 4-cyclohexane Diisocyanate, methyl-2, 4-cyclohexane diisocyanate, methyl-2, 6-cyclohexane diisocyanate, 4, 4'-methylenebis (cyclohexyl isocyanate), and 1, 4-bis (isocyanate methyl) cyclohexane And the like.

The polyisocyanate is a diisocyanate, but a triisocyanate modified from the diisocyanate can also be used. Examples of the triisocyanate include trimethylolpropane adduct, biuret, and trimer of the diisocyanate (this trimer contains an isocyanurate ring).

As for the polyisocyanate (x), 4, 4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and 3-isocyanate methyl-3, 5, 5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) etc. are preferable. .

Polyisocyanate (x) can be used alone or in combination of two or more.

<Polyol (y)>

Polyol (y) is a compound having two or more hydroxyl groups. The polyol (y) is preferably a known compound such as polyether polyol, polyester polyol, and polycarbonate polyol.

The polyol (y) used in the present invention preferably contains, as a main component, a polyol having two hydroxyl groups in order to realize appropriate cohesive strength and adhesive strength of the adhesive layer. In addition, when a polyol having three or more hydroxyl groups is used in combination, it is preferable to use it with less mass than a polyol having two hydroxyl groups.

The polyether polyol is, for example, a reaction product in which an active hydrogen-containing compound having two or more active hydrogens in one molecule is used as an initiator and at least one oxirane compound is addition-polymerized.

As the active hydrogen-containing compound, a hydroxyl group-containing compound and an amine are preferable.

Examples of the hydroxyl group-containing compound include bifunctional active hydrogen-containing compounds such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, and butyl ethyl pentanediol; glycerin, trimethylolpropane, etc. Trifunctional active hydrogen-containing compounds of; and tetrafunctional active hydrogen-containing compounds such as pentaerythritol.

The amine is, for example, compounds containing bifunctional active hydrogen such as N-aminoethylethanol amine, isophorone diamine, and xylylene diamine; trifunctional active hydrogen-containing compounds such as triethanol amine; ethylene diamine, and aromatic diamine. Tetrafunctional active hydrogen-containing compounds; 5-functional active hydrogen-containing compounds, such as diethylene triamine, etc. are mentioned.

Examples of the oxirane compound include alkylene oxides (AO) such as ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO); tetrahydrofuran (THF), and the like. .

It is preferable that the polyether polyol has an alkylene oxy group derived from an active hydrogen-containing compound in its molecule (this polyol is also referred to as "polyoxyalkylene polyol"). The polyoxyalkylene polyol is preferably a difunctional polyether polyol such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and particularly preferably polypropylene glycol which has low crystallinity and provides flexibility. Since the bifunctional polyether polyol has a two-dimensional crosslinking property, it is possible to obtain an appropriate adhesive force and cohesive force for the adhesive layer.

The number average molecular weight (Mn) of the polyether polyol is not particularly limited, and since transparency and flexibility are effectively expressed, 200 to 6,000 are preferable, 400 to 4,000 are more preferable, and 600 to 4,000 are still more preferable. By setting Mn to 200 or more, it is easy to control the reaction during synthesis of the urethane prepolymer containing an isocyanate group. Further, by setting Mn to 6, 000 or less, it is easy to adjust the cohesive force to the urethane urea resin in an appropriate range.

The polyester polyol is preferably a compound (esterified product) obtained by esterifying one or more polyol components and one or more acid components, or a compound synthesized by ring-opening polymerization of lactone (ring-opening polymerization product).

Examples of the lactone include polycaprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

The polyol component is, for example, ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, 3-methyl-1, 5-pentane Diol, 2-butyl-2-ethyl-1, 3-propanediol, 2, 4-diethyl-1, 5-pentanediol, 1, 2-hexanediol, 1, 6-hexanediol, 2-ethyl-1 , 3-hexanediol, 1, 8-octanediol, 1, 9-nonane diol, 2-methyl-1, 8-octanediol, 1, 8-decane diol, octadecane diol, glycerin, trimetyrolpropane, penta Erythritol, hexanetriol, and the like.

The acid component is, for example, succinic acid, methyl succinic acid, adipic acid, pyromellitic acid, azeric acid, sebacic acid, 1, 12-dodecane diacid, 1, 14-tetradecane diacid, dimer acid, 2-methyl- 1, 4-cyclohexanedicarboxylic acid, 2-ethyl-1, 4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1, 4-naphthalene dicarboxylic acid, and 4, 4'-ratio Phenyldicarboxylic acid, and such acid anhydrides.

As for the number average molecular weight (Mn) of the polyester polyol, 200-8,000 are preferable, 500-6,000 are more preferable, 500-4,000 are still more preferable, and 500-3,000 are especially preferable. By setting Mn to 200 or more, it is easy to control the reaction during synthesis of the urethane prepolymer containing an isocyanate group. Further, by setting Mn to 8,000 or less, it is easy to adjust the cohesive force to the urethane urea resin in an appropriate range.

Other polyols other than the above include, for example, polycarbonate polyol, butadiene-based polyol, castor oil polyol, and the like. Other polyols are preferably used in combination with polyether polyol or polyester polyol.

Other polyols have a number average molecular weight (Mn) of about 200 to 8,000.

The polyol (y) is preferably a polyether polyol.

Further, if the polyol (y) contains an acidic functional group such as a carboxyl group or a sulfo group, it may corrode the adherend. Therefore, when applying the pressure-sensitive adhesive for surface protection of the present application to an adherend that is easily corroded, it is preferable to use a polyol having no acidic functional group.

The polyol (y) can be used alone or in combination of two or more.

<Catalyst>

The catalyst is preferably, for example, a tertiary amine compound and an organometallic compound.

Examples of the tertiary amine-based compound include triethyl amine, triethylene diamine, and 1,8-diazabicyclo(5.5.4.0)-undecene-7 (DBU).

As the organometallic compound, a tin-based compound and a non-tin-based compound are preferable.

Tin-based compounds include, for example, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, Dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichlor Rhoacetate, and tin 2-ethylhexanoate, etc. are mentioned.

Non-tin-based compounds include, for example, titanium-based compounds such as dibutyl titanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate. Lead-based compounds of; Iron-based compounds such as iron 2-ethylhexanoate and iron acetylacetonate; Cobalt-based compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; Zinc-based compounds such as zinc naphthenate and zinc 2-ethylhexanoate Zirconium-based compounds, such as zirconium naphthenate, are mentioned.

The catalyst can be used alone or in combination of two or more.

As for the catalyst, it is preferable to use 0.01 to 1.0 mass parts with respect to 100 mass parts in total of polyisocyanate (x) and polyol (y).

When a plurality of polyols (y) are used for the synthesis of the urethane prepolymer (a) containing an isocyanate group, and each has a different reactivity, using one type of catalyst fails to control the reaction and the synthesis proceeds with each polyol alone. The reaction liquid may become cloudy. In this case, when two types of catalysts are used, it is easy to control the reaction (eg, reaction rate, etc.), and the above problem can be solved. That is, in the present invention, when using a plurality of polyols (y), it is preferable to use two or more types of catalysts. The combination of the two types of catalysts is not particularly limited, and includes tertiary amine/organometallic, tin/nontin, and tin/tin. Among these, tin type/tin type are preferable, and dibutyltin dilaurate and tin 2-ethylhexanoate are more preferable.

The mass ratio of 2-ethylhexanoate tin and dibutyltin dilaurate (2-ethylhexanoate tin/dibutyltin dilaurate) is not particularly limited, preferably more than 0 and less than 1, more preferably 0.2 to 0.6. If the mass ratio is used within an appropriate range, reaction control becomes easy.

<Solvent>

In the synthesis of the urethane prepolymer (a) containing an isocyanate group, one or more solvents can be used as necessary. As a solvent, methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, etc. are mentioned, for example. Among these, ethyl acetate, toluene, etc. are preferable from the viewpoints of the solubility of the urethane prepolymer (a) containing an isocyanate group and the boiling point of the solvent.

<polymerization method>

The polymerization method of the isocyanate group-containing urethane prepolymer (a) is not particularly limited, and known polymerization methods such as a bulk polymerization method and a solution polymerization method can be used.

The polymerization sequence is, for example,

Step 1) At least one polyisocyanate (x), at least one polyol (y), if necessary, at least one catalyst, and if necessary, at least one solvent are injected into the flask collectively;

Step 2) At least one polyol (y), if necessary, one or more catalysts, and if necessary, one or more solvents are poured into the flask, and at least one polyisocyanate (x) is added dropwise to the flask. Can be lifted.

Among these, since the low molecular weight component in the material is preferentially reacted, the molecular weight dispersion degree is narrowed, and reaction control is easy, step 2) is preferred.

When a catalyst is used, the reaction temperature is preferably less than 100°C, and more preferably 85 to 95°C. If the reaction temperature is less than 100°C, side reactions other than the urethane reaction can be suppressed, so that the desired resin can be easily obtained.

When a catalyst is not used, the reaction temperature is preferably 100°C or higher, and more preferably 110°C or higher.

The reaction time of urethane often takes about 1 hour or more when a catalyst is used. In addition, when no catalyst is used, it often takes about 3 hours or more.

When synthesizing an isocyanate group-containing urethane prepolymer (a), the isocyanate group (NCO) of the polyisocyanate (x) and the hydroxyl group (OH) of the polyol (y) are preferably 1.1 to 2 in terms of the molar ratio of NCO/OH. , 1.1 to 1.8 are more preferable, and 1.2 to 1.6 are still more preferable. Since the urethane prepolymer having an appropriate molecular chain can be formed by making the NCO/OH ratio in an appropriate range, the wettability and productivity are further improved.

<Amine compound (b)>

The urethane urea resin (A) is a reaction product obtained by reacting a urethane prepolymer (a) containing at least one isocyanate group and at least one amine compound (b) with a urea reaction.

The amine compound (b) is preferably a monoamine, a diamine, or a trifunctional or higher amine, more preferably a diamine or a trifunctional or higher amine, further preferably a diamine having a hydroxyl group or a trifunctional or higher amine, and two or more amino groups. Or compounds having at least one amino group and at least one hydroxyl group are particularly preferred. By using the amine compound (b), the cohesive strength can be improved by urea bonding without depending on the molecular weight of the urethane urea resin (A). In particular, when the urethane urea resin (A) has a primary hydroxyl group, since the reaction rate is fast, the time until completion of curing is short, and productivity is further improved.

The amine compound (b) is, for example, ethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, triethylene tetramine, diethylene triamine, triaminopropane, 2, 2, 4- Trimethylhexamethylene diamine, 2-hydroxyethylethylene diamine, diethanol amine, diisopropanol amine, 1-methylamino-2, 3-propanediol, N-(2-hydroxyethyl)propylene diamine, N-(3- Hydroxypropyl) ethylene diamine, (2-hydroxyethylpropylene) diamine, (di-2-hydroxyethylethylene) diamine, (di-2-hydroxyethylpropylene) diamine, (2-hydroxypropylethylene) diamine , (Di-2-hydroxypropylethylene) aliphatic amine compounds such as diamine and piperazine; alicyclic amine compounds such as isophorone diamine, dicyclohexylmethane-4, and 4'-diamine; phenylene diamine, xylylene Diamine, 2, 4-tolylene diamine, 2, 6-tolylene diamine, diethyltoluene diamine, 3, 3'-dichloro-4, 4'-diaminodiphenylmethane, 4, 4'-bis-(sec -Butyl) aromatic diamine such as diphenylmethane; and dimer-diamine in which the carboxyl group of dimer acid is converted to an amino group; and dendrimers having a primary or secondary amino group at the terminal thereof.

Further, as the amine compound (b), a polyoxyalkylene glycol diamine represented by the following general formula [2] having propoxy amine at both ends of the molecule can be used.

General formula [2]:

H ₂ N-CH ₂ -CH ₂ -CH ₂ -O-(C _m H _2m -O) _n -CH ₂ -CH ₂ -CH ₂ -NH ₂

(In the formula, m represents an arbitrary integer of 2 to 4, and n represents an arbitrary integer of 2 to 50.)

Among these amine compounds (b), a compound having two or more secondary amino groups and one primary hydroxyl group is preferable from the viewpoint of controlling the urea reaction. As the compound, a known compound can be used without limitation.

As an example of the synthesis method of a compound having two or more secondary amino groups and one primary hydroxyl group, a compound having at least one hydroxyl group and a (meth) acryloyl group in a compound having two or more primary amino groups Compounds subjected to the Michael addition reaction are preferred. The hydroxyl group possessed by the compound is preferably a primary hydroxyl group. Thereby, the time until the completion of curing of the urethane urea resin and the isocyanate curing agent is short, and since the coating speed can be made high, productivity is further improved.

Examples of the compound having two or more primary amino groups include the compounds exemplified in the amine compound (b). Among these, isophorone diamine, 2, 2, 4-trimethylhexamethylene diamine, and hexamethylene diamine are preferable because the Michael addition reaction can be easily controlled.

The polymerization method of the urethane urea resin (A) is not particularly limited, and if a known polymerization method can be applied, from the viewpoint of reaction control of the urea reaction, a catalyst is used when synthesizing the urethane prepolymer (a) containing an isocyanate group. When used, it is preferable to deactivate the catalyst. For the inactivation, for example, acetylacetone or the like may be blended.

In the order of polymerization of the urethane urea resin (A), an isocyanate group-containing urethane prepolymer (a) and one or more solvents, if necessary, are injected into the flask, and an amine compound (b) is added dropwise thereto over time under relatively low temperature conditions. The order of doing this is preferable. As a result, since the low molecular weight component is preferentially reacted and the molecular weight dispersion degree can be narrowed, all aptitudes to the curved portion are further improved.

In addition, unreacted isocyanate groups can be lost by reacting the reaction terminator after reacting the amine compound (b) with the urethane prepolymer (a) containing an isocyanate group. Thereby, the aging stability of the main body of the pressure-sensitive adhesive before blending of the isocyanate curing agent (B) is further improved. In addition, the main material means a composition excluding a curing agent from an adhesive.

The reaction terminator is preferably a monoamine. Moreover, it is preferable that a monoamine has a hydroxyl group which becomes a crosslinking point with an isocyanate hardening agent (B).

As for monoamine, 2-amino-2-methyl-1-propanol is mentioned, for example.

The reaction terminator can be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the urethane urea resin (A) is preferably 30,000-250,000, more preferably 30,000-200,000, and still more preferably 50,000-200,000. By making the weight average molecular weight (Mw) within the above range, all aptitudes to the curved portion are further improved.

1.5-6 are preferable, as for the molecular weight dispersion degree of urethane urea resin (A), 2-5 are more preferable, and 2.5-4 are still more preferable. If the molecular weight dispersion degree is less than 1.5, the difficulty of synthesis is high. Moreover, since the low molecular weight component can be suppressed by setting the molecular weight dispersion degree to 6 or less, all suitability to a curved surface part is improved more.

(Isocyanate curing agent (B))

The isocyanate curing agent (B) is a known compound having a plurality of isocyanate groups. As for the isocyanate curing agent (B), the polyisocyanate (x) previously described is preferable, and among them, aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates, and such trimethylolpropane adducts, and More preferable are such burettes and trifunctional isocyanates, which are trimers thereof.

The isocyanate curing agent (B) can be used alone or in combination of two or more.

The blending amount of the isocyanate curing agent (B) is preferably more than 3 parts by mass and 20 parts by mass or less, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the urethane urea resin (A). When an appropriate amount of the isocyanate curing agent (B) is blended, it is easy to obtain an appropriate adhesive strength and cohesive strength.

(Plasticizer (C))

The pressure-sensitive adhesive for surface protection of the present invention may further contain a plasticizer (C). When the plasticizer (C) is included, the wettability of the adhesive layer to the adherend is further improved. The plasticizer (C) is preferably a fatty acid ester or phosphoric acid ester having 8 to 30 carbon atoms from the viewpoint of compatibility with other components.

Fatty acid esters having 8 to 30 carbon atoms are, for example, esters of monobasic or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, esters of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and alcohols having tetrahydric or less And esters of a monobasic acid or polybasic acid having 6 to 18 carbon atoms and polyalkylene glycol, and a fatty acid ester obtained by epoxidating an unsaturated site with a peroxide or the like.

Esters of monobasic or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms include, for example, isostearyl laurate, isopropyl myristic acid, isocetyl myristic acid, octyldodecyl myristic acid. , Isostearyl palmitate, isocetyl stearate, octyldodecyl oleate, diisostearyl adipic acid, diisocetyl sebacic acid, trioleyl trimellitic acid, and triisocetyl trimellitic acid.

Examples of the unsaturated fatty acid or branched acid having 14 to 18 carbon atoms include myristic acid, oleic acid, linoleic acid, linolenic acid, isopalmitic acid, and isostearic acid. Examples of the tetrahydric or lower alcohol include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, and sorbitan.

Examples of esters of monobasic or polybasic acids having 6 to 18 carbon atoms and polyalkylene glycol include polyethylene glycol dihexyl, polyethylene glycol di-2-ethylhexyl, polyethylene glycol dilauryl, polyethylene glycol dioleate, and dipolyethylene adipic acid. And glycol methyl ether.

Fatty acid esters obtained by epoxidizing the unsaturated site with a peroxide, for example, epoxidized soybean oil, epoxidized flaxseed oil, epoxidized cottonseed oil, etc., or a compound obtained by epoxidating an unsaturated fatty acid having 8 to 18 carbon atoms and 1 to carbon atoms And ester compounds with 6 linear or branched alcohols.

The phosphoric acid ester includes, for example, an ester compound of phosphorous acid or phosphoric acid and a linear or branched alcohol having 2 to 18 carbon atoms.

The plasticizer (C) can be used alone or in combination of two or more.

The number average molecular weight (Mn) of the plasticizer (C) is preferably 300 to 1000, more preferably 300 to 900, and even more preferably 350 to 850 from the viewpoint of improving the wetting speed.

The blending amount of the plasticizer (C) is preferably 0.1 to 100 parts by mass, more preferably 1 to 80 parts by mass, and even more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the urethane urea resin (A). When the plasticizer (C) is blended in an appropriate amount, the wettability is further improved.

(Antioxidant (D))

The pressure-sensitive adhesive for surface protection of the present invention may further contain an antioxidant (D). When the antioxidant (D) is included, thermal deterioration of the urethane urea resin (A) can be suppressed.

The antioxidant is preferably a radical chain inhibitor such as a phenolic antioxidant and an amine antioxidant, and a sulfur antioxidant or phosphorus antioxidant.

Phenolic antioxidants are, for example, 2, 6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2, 6-di-t-butyl-4-ethylphenol, and stearin-β Monophenolic antioxidants such as -(3,5-di-t-butyl-4-hydroxyphenyl) propionate;

2, 2'-methylenebis (4-methyl-6-t-butylphenol), 2, 2'-methylenebis (4-ethyl-6-t-butylphenol), 4, 4'-thiobis (3- Methyl-6-t-butylphenol), 4, 4'-butylidenebis (3-methyl-6-t-butylphenol), and 3, 9-bis[1,1-dimethyl-2-[β-] (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] 2, 4, 8, 10-tetraoxaspiro [5, 5] bisphenol antioxidants such as undecane;

1, 1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1, 3, 5-trimethyl-2, 4, 6-tris (3, 5-di-t- Butyl-4-hydroxybenzyl) benzene, tetrakis-[methylene-3-(3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3, 3' -Bis-(4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, and 1, 3, 5-tris (3', 5'-di-t-butyl-4'-hydride And polymeric phenolic antioxidants such as oxybenzyl)-S-triazine-2, 4, 6-(1H, 3H, 5H) trione and tocopherol.

Sulfur-based antioxidants are, for example, dilauryl 3, 3'-thiodipropionate, dimyristyl 3, 3'-thiodipropionate, and distearyl 3, 3'-thiodipropionate. And the like.

*

Examples of the phosphorus antioxidant include triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite.

Antioxidant (D) may be used alone or in combination of two or more.

The blending amount of the antioxidant (D) is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the urethane urea resin (A).

(Antistatic agent (E))

The pressure-sensitive adhesive for surface protection of the present invention may further contain an antistatic agent (E). When the antistatic agent (E) is included, it is easy to suppress electrostatic discharge when peeling the pressure-sensitive adhesive sheet, and to prevent damage to, for example, parts assembled on a display or the like.

Examples of the antistatic agent include inorganic salts, polyhydric alcohol compounds, ionic liquids, and surfactants. Among these, an ionic liquid is preferable. In addition, "ionic liquid" is also called a room temperature melting salt, and shows the property of a liquid at 25 degreeC.

Inorganic salts are, for example, sodium chloride, potassium chloride, lithium chloride, lithium perchlorate, ammonium chloride, potassium chlorate, aluminum chloride, copper chloride, ferrous chloride, ferric chloride, ammonium sulfate, potassium nitrate, sodium nitrate, sodium carbonate , And sodium thiocyanate.

Examples of the polyhydric alcohol compound include propanediol, butanediol, hexanediol, polyethylene glycol, trimethylolpropane, pentaerythritol, and the like.

The ionic liquid is a salt of a cation and an anion, and the cation is preferably an imidazolium ion, a pyridinium ion, an ammonium ion, or the like.

Ionic liquids containing imidazolium ions are, for example, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1,3-dimethylimidazolium bis(trifluoro). Romethylsulfonyl) imide, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, etc. are mentioned.

An ionic liquid containing a pyridinium ion is, for example, 1-methylpyridinium bis(trifluoromethylsulfonyl) imide, 1-butylpyridinium bis(trifluoromethylsulfonyl) imide, 1 -Hexylpyridinium bis (trifluoromethylsulfonyl) imide, 1-octylpyridinium bis (trifluoromethylsulfonyl) imide, 1-hexyl-4-methylpyridinium bis (trifluoromethylsulfur) Phonyl) imide, 1-hexyl-4-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium bis(trifluoromethylsulfonyl) imide, 1-octyl-4-methylpyridinium bis (Fluorosulfonyl) imide, 1-methylpyridinium bis(perfluoroethylsulfonyl) imide, and 1-methylpyridinium bis(perfluorobutylsulfonyl) imide, etc. are mentioned.

The ionic liquid containing ammonium ions is, for example, trimethylheptylammonium bis(trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis(trifluoromethane) Sulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis(trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis( Trifluoromethanesulfonyl) imide, and tri-n-butylmethylammonium bistrifluoromethanesulfonimide.

In addition, a known ionic liquid in which the cation is a pyrrolidinium salt, a phosphonium salt, and a sulfonium salt can be suitably used.

Surfactants can be classified into nonionic, anionic, cationic, and amphoteric types.

Nonionic types are, for example, glycerin fatty acid ester, polyoxyalkylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamine fatty acid ester, fatty acid diethanol amide, polyether ester. Amide type, ethylene oxide-epichlorohydrin type, and polyether ester type.

Examples of the anionic type include an alkyl sulfonate, an alkylbenzene sulfonic acid salt, an alkyl phosphate, and a polystyrene sulfonic acid type.

Examples of the cationic type include tetraalkyl ammonium salt, trialkyl benzylammonium salt, and quaternary ammonium base-containing acrylate polymer type.

The amphoteric type is, for example, an amino acid type amphoteric surfactant such as alkyl betaine and alkyl imidazolium betaine, higher alkylamino propionate, higher alkyl dimethyl betaine, and higher alkyl dihydroxyethyl betaine. Betain type amphoteric surfactant, etc. are mentioned.

The antistatic agent (E) can be used alone or in combination of two or more.

The blending amount of the antistatic agent (E) is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass with respect to 100 parts by mass of the urethane urea resin (A).

(solvent)

The pressure-sensitive adhesive for surface protection of the present invention may contain a solvent, if necessary. Examples of the solvent include known compounds such as methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these, ethyl acetate and toluene are preferable from the viewpoints of compatibility with the urethane urea resin (A) and the boiling point of the solvent.

Solvents can be used alone or in combination of two or more.

(Optional ingredient)

The pressure-sensitive adhesive for surface protection of the present invention may contain an optional component as necessary as long as it is within a range that can solve the problem. Optional components are resins other than urethane resins, fillers, metal powders, pigments, thin materials, softeners, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat-resistant stabilizers, polymerization inhibitors, antifoaming agents. , And lubricants.

As a filler, talc, calcium carbonate, titanium oxide, etc. are mentioned, for example.

Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, oxalate anilide-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

Benzophenone-based ultraviolet absorbers are, for example, 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2-hydroxy- 4-Dodecyloxybenzophenone, 2, 2'-dihydroxy-4-dimethoxybenzophenone, 2, 2'-dihydroxy-4, 4'-dimethoxybenzophenone, 2-hydroxy-4- Methoxy-5-sulfobenzophenone, and bis(2-methoxy-4-hydroxy-5-benzoylphenyl) methane, etc. are mentioned.

The benzotriazole-based ultraviolet absorber, for example, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2-(2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5- Chlorobenzotriazole, 2-(2'-hydroxy-3', 5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3', 5'- Di-tert-amylphenyl) benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2-[2'-hydroxy-3'-(3'', 4' ', 5'', 6''-tetrahydrophthalimide methyl)-5'-methylphenyl]benzotriazole, 2, 2'-methylenebis[4-(1, 1, 3, 3-tetramethylbutyl) -6-(2H-benzotriazole-2-yl) phenol], and [2-(2'-hydroxy-5'-methacryloxyphenyl)-2H-benzotriazole, etc. are mentioned.

Examples of the salicylic acid-based ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

The cyanoacrylate ultraviolet absorber is, for example, 2-ethylhexyl-2-cyano-3, 3'-diphenyl acrylate, and ethyl-2-cyano-3, 3'-diphenyl acrylate, etc. Can be mentioned.

Examples of the light stabilizer include hindered amine light stabilizers and ultraviolet stabilizers.

The hindered amine light stabilizer is, for example, [bis(2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate], bis(1, 2, 2, 6, 6-pentamethyl -4-piperidyl) sebacate, and methyl 1, 2, 2, 6, 6-pentamethyl-4-piperidyl sebacate, etc. are mentioned.

UV stabilizers are, for example, nickel bis (octylphenyl) sulfide, [2, 2'-thiobis (4-tert-octyl phenolate)] -n-butylamine nickel, nickel complex-3, 5-di- tert-butyl-4-hydroxybenzyl-phosphate monoethyrate, nickel-dibutyl dithiocarbamate, benzoate-type quencha, and the like.

Examples of the leveling agent include an acrylic leveling agent, a fluorine leveling agent, and a silicone leveling agent. Examples of commercially available leveling agents include acrylic leveling agents, such as POLYFLOW No.36, POLYFLOW No.56, POLYFLOW No.85 HF, and POLYFLOW No.99 C (all manufactured by KYOEISHA CHEMICAL CO., Ltd.). I can. Examples of the fluorine-based leveling agent include Megapack F470N and Megapack F556 (all manufactured by DIC). Examples of the silicone leveling agent include GRANDIC PC4100 (manufactured by DIC).

[Adhesive sheet]

The adhesive sheet of the present invention includes a substrate and an adhesive layer that is a cured product of an adhesive for surface protection. The adhesive layer can be formed on one side or both sides of the substrate. In addition, the surface of the adhesive layer that is not in contact with the substrate is usually protected with a release sheet until immediately before use, since adhesion of foreign matters is prevented.

As for the base material, flexible sheets and boards can be used without limitation. Examples of the substrate include plastic, paper, and metal foil, and such laminates.

In order to improve the adhesion on the surface of the substrate in contact with the adhesive layer, for example, a dry treatment such as a corona discharge treatment or a wet treatment such as application of an anchor coat agent may be previously subjected to a reverse adhesion treatment.

The plastics of the base material are, for example, ester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); olefin resins such as polyethylene (PE), polypropylene (PP) and cycloolefin polymer (COP). ; Vinyl resins, such as polycarbonate vinyl; Amide resins, such as nylon 66; Urethane resin (including foam); etc. are mentioned.

The thickness of the substrate is usually about 10 to 300 μm, excluding the polyurethane sheet. In addition, when a polyurethane sheet (including a foam) is used as the substrate, the thickness is usually about 20 to 50,000 µm.

As for paper, plain paper, coated paper, art paper, etc. are mentioned, for example.

As for the metal foil, aluminum foil, copper foil, etc. are mentioned, for example.

As the release sheet, a known release sheet in which a known release treatment such as a silicone-based release agent is provided on the surface of plastic or paper can be used.

The manufacturing method of the adhesive sheet includes, for example, a method of forming an adhesive layer by coating an adhesive on the surface of a substrate to form a coating layer, and then drying and curing the coating layer. The heating and drying temperature is usually about 60 to 150°C. The thickness of the adhesive layer is usually about 0.1 to 200 µm.

Examples of the coating method include a known method such as a roll coater method, a comma coater method, a die coater method, a reverse coater method, a silk screen method, and a gravure coater method.

In contrast to the above method, a pressure-sensitive adhesive is applied to the surface of the release sheet to form a coating layer, and then the coating layer is dried and cured to form a pressure-sensitive adhesive layer comprising a cured product of the pressure-sensitive adhesive of the present invention, and finally A method of bonding the substrate to the exposed surface of the adhesive layer may be mentioned. When the release sheet is bonded instead of the substrate in the above method, a cast adhesive sheet of a release sheet/adhesive layer/release sheet is obtained.

[Example]

Hereinafter, embodiments of the present invention will be described with examples. In addition, it goes without saying that the embodiment of the present invention is not limited to the examples. Hereinafter, "part" means "mass part", and "%" means "mass%".

[Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)]

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by a gel permeation chromatography (GPC) method. Measurement conditions are as follows. In addition, both Mw and Mn are polystyrene conversion values.

<Measurement conditions>

Device: Shimadzu Prominence (manufactured by Shimadzu Corporation),

Column: 3 SHODEX LF-804 (manufactured by SHOWA DENKO K.K.) are connected in series,

Detector: differential refractive index detector,

Solvent: tetrahydrofuran (THF),

Flow rate: 0.5 mL/min,

Solvent temperature: 40°C,

Sample density: 0.1%,

Sample injection volume: 100 μL.

[material]

The materials used are as follows.

<Polyisocyanate (x)>

(x1): HDI (hexamethylene diisocyanate, "Desmodur H" manufactured by Covestro Japan Ltd.),

(x2): IPDI (isophorone diisocyanate, "Desmodur I" manufactured by Covestro Japan Ltd.),

(x3): XDI (xylylene diisocyanate, "Takenate 500" manufactured by Mitsui Chemicals Inc.).

<Polyol (y)>

(y1): PPG600 ("SANNIX PP-600", polyoxypropylene glycol, Mn600, number of hydroxyl groups 2, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

(y2): PPG1000 ("SANNIX PP-1000", polyoxypropylene glycol, Mn1000, number of hydroxyl groups 2, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

(y3): PPG2000 ("SANNIX PP-2000", polyoxypropylene glycol, Mn2000, number of hydroxyl groups 2, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

(y4): PPG4000 ("SANNIX PP-4000" polyoxypropylene glycol, Mn4000, number of hydroxyl groups 2, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

(y5): PX1000 ("primepol PX-1000", terminal primary modified polyoxypropylene glycol, Mn1000, number of hydroxyl groups 2, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.)

(y6): P1010 ("kuraray polyol P-1010", polyester polyol, Mn1000, number of hydroxyl groups 2, manufactured by Kuraray Co. Ltd.)

(y7): GI1000 (NISSO-PB　GI-1000", hydrogenated polybutadiene at both ends, Mn1000, number of hydroxyl groups 2, manufactured by NIPPON SODA CO., LTD.)

(y8): C1090 ("kuraray polyol 　C-1090", polycarbonate polyol, Mn1000, number of hydroxyl groups 2, manufactured by Kuraray Co. Ltd.)

(y9): AM302 ("ADEKA POLYETHER　AM-302", glycerin PO/EO polyol, Mn3000, number of hydroxyl groups 3, manufactured by ADEKA)

(y10): T-500 ("POLYHARDENER T-500", polyoxypropylene glyceryl ether, Mn5000, number of hydroxyl groups 3, manufactured by DKS Co. Ltd.),

(y11): D-660 ("HI-LUBE D-660", polypropylene glycol, Mn3000, number of hydroxyl groups 2, manufactured by DKS Co. Ltd.),

(y12): BPEF ("bisphenoxyethanolfluorene", 9, 9-bis[4-(2-hydroxyethoxy)phenyl]fluorene, food 438.5, number of hydroxyl groups 2, manufactured by JFE CHEMICAL CORPORATION),

<Synthesis of amine compound (b)>

*(b1): 25.0 parts of isophorone diamine (IPDA) and 25.0 parts of toluene are poured into a 4-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping lot, and 4-hydroxybutyl acrylate 21.1 parts A mixture of 18.8 parts of and butyl acrylate was dripped at room temperature from a dropping lot. After completion of the dropwise addition, the internal temperature was gradually raised to 80° C., and after reacting for 2 hours while maintaining 80° C., 39.9 parts of toluene was added to obtain a solution of Compound (1) having 2 secondary amino groups and 1 primary hydroxyl group.

(b2): 40.0 parts of isophorone diamine (IPDA) and 40.0 parts of toluene were poured into a 4-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping lot, and 67.7 parts of 4-hydroxybutylacrylate was added dropwise. It was dripped at room temperature from a lot. After the dropwise addition, the inner temperature was gradually raised to 80°C, and after reacting at 80°C for 2 hours while maintaining 80°C, 67.7 parts of toluene was added to a compound (2) solution having 2 secondary amino groups and 2 primary hydroxyl groups. Got it.

(b3): HPEA; N-(3-hydroxypropyl) ethylenediamine (manufactured by TOKYO CHEMICAL INDUSTRY CO., LTD.)

(b4): DEA; diethanolamine (manufactured by TOKYO CHEMICAL INDUSTRY CO., LTD.)

(b5): DIPA; diisopropanolamine (manufactured by TOKYO CHEMICAL INDUSTRY CO., LTD.)

(b6):MAPD; 1-methylamino-2, 3-propanediol (manufactured by Daicel Corporation)

(b7): AMP; 2-amino-2-methyl-1-propanol (manufactured by Dow Chemical Company)

<Isocyanate curing agent (B)>

(B1): HDI adduct ("Sumidur HT", trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Covestro Japan Ltd.)

(B2): HDI nurate ("Sumidur N3300", a nurate product of hexamethylene diisocyanate, manufactured by Covestro Japan Ltd.)

(B3): HDI burette ("Sumidur N3200", a burette body of hexamethylene diisocyanate, manufactured by Covestro Japan Ltd.)

<Plasticizer (C)>

(C1): M182A ("Unistar M182A", methyl oleate, NOF Corporation make)

(C2): W262 ("Monocizer-W262", ether ester plasticizer, manufactured by DIC)

(C3): E-6000 ("Sansosaiza E-6000", epoxidized fatty acid 2-ethylhexyl, manufactured by New Japan Chemical Co.)

(C4): TOP ("TOP", tris(2-ethylhexyl) phosphate, manufactured by DAIHACHI CHEMICAL INDUSTRY CO., LTD.)

<Antioxidant (D)>

(D1): Irg1010 ("IRGANOX 1010", pentaerythritol tetrakis [3-(3, 5-ditert-butyl-4-hydroxyphenyl) propionate], manufactured by BASF)

<Antistatic agent (E)>

(E1): FSI-ammonium salt (tri-n-butyl, methylammonium, bistrifluoromethanesulfonimide)

(E2): FSI-lithium salt (lithium bistrifluoromethanesulfonimide)

[Synthesis example of urethane urea resin (A)]

(Synthesis Example 1)

SANNIX PPG600 (bifunctional polypropylene glycol, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.) 628 parts, isophorone diisocyanate 372 parts, toluene 250 in a 4-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping lot. Part, 0.1 part of dioctyltin dilaurate was injected as a catalyst, and the temperature was gradually raised to 100°C, followed by reaction for 2 hours. After cooling to 25°C and adding 750 parts of ethyl acetate and 3 parts of acetylacetone, 220 parts of compound (1) were added dropwise in 2 hours, and the reaction was continued at 25°C for 1 hour. After confirming the remaining amount of isocyanate groups by titration, 23 parts of 2-amino-2-methyl-propanol was added, and it was confirmed that the absorption of the NCO characteristic (2, 270 cm ^{- 1} ) of the IR chart had disappeared, and the reaction was terminated. The weight average molecular weight Mw of this urethane urea resin (A1) was 143,000, and the molecular weight dispersion degree was 5.8.

Table 1 shows the types of materials used, such mixing ratios, and Mw and molecular weight dispersion of the obtained urethane urea resin (A1). In addition, the blending amount of the material in the table is in terms of non-volatile components, and the unit is [part].

(Synthesis Examples 2 to 16)

Except having changed the material of Example 1 and the compounding ratio as shown in Table 1, it carried out similarly to Synthesis Example 1, and obtained the resin of Synthesis Examples 2-16, respectively.

(Synthesis Example 17)

Into a four-neck flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel, 40 parts of P1010 and 160 parts of AM302 were injected. To this, 200 parts of toluene, 0.03 parts of dibutyltin dilaurate and 0.01 parts of tin 2-ethylhexanoate were added as a catalyst, and the temperature was gradually raised to 90°C. What mixed 13 parts of HDI and 13 parts of toluene was dripped over 1 hour, and reaction was performed for 1 hour after dripping. After occasional sampling was performed and disappearance of the remaining isocyanate groups was confirmed by an infrared absorption (IR) spectrum, the reaction solution was cooled and the reaction was terminated. The weight average molecular weight Mw of this urethane urea resin was 144,000, and the molecular weight dispersion degree was 6.1.

(Synthesis Example 18)

799 parts of SANNIX PPG1000 (bifunctional polypropylene glycol, manufactured by SANYO CHEMICAL INDUSTRIES, LTD.), 146 parts of hexamethylene diisocyanate, 250 parts of toluene in a 4-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping lot. Part, 0.1 part of dioctyltin dilaurate was injected as a catalyst, and the temperature was gradually raised to 100°C, followed by reaction for 2 hours. After cooling to 70°C, 750 parts of toluene and 3 parts of acetylacetone were added, then 27 parts of compound (1) were added dropwise over 30 minutes, and the reaction was further continued at 70°C for 1 hour. After confirming the remaining amount of isocyanate groups by titration, 0.8 parts of 2-amino-2-methyl-propanol was added to confirm that the NCO characteristic absorption (2, 270 cm ^{- 1} ) of the IR chart had disappeared, and the reaction was terminated. The weight average molecular weight Mw of this urethane urea resin (A18) was 230,000, and the molecular weight dispersion degree was 6.9.

(Example 1)

100 parts of the urethane urea resin (A1) obtained in Synthesis Example 1, 3.5 parts of an isocyanate curing agent (B1), 0.5 parts of an antioxidant (D1), and 100 parts of ethyl acetate as a solvent were mixed, and stirred with a disper to obtain a pressure-sensitive adhesive. In addition, the amount of use of each material excluding the solvent represents the value in terms of nonvolatile components.

A 25 µm-thick polyethylene terephthalate (PET) ("Lumilar T-60", manufactured by TORAY INDUSTRIES, INC.) was prepared on the substrate. Using a Comma coater (registered trademark), the obtained pressure-sensitive adhesive was applied on the substrate at a coating speed of 3 m/min so that the thickness after drying became 12 µm to form a coating layer.

Then, the formed coating layer was dried using a drying oven at 100° C. for 2 minutes to form an adhesive layer. A pressure-sensitive adhesive sheet was obtained by bonding a commercial release sheet having a thickness of 38 µm on the pressure-sensitive adhesive layer and further curing for one week under conditions of 23°C -50%RH.

*

(Examples 2 to 36, Comparative Examples 1 to 4)

Except having changed the material and compounding ratio of Example 1 as shown in Table 2, it carried out similarly to Example 1, and obtained the adhesive and the adhesive sheet of Examples 2 to 36 and Comparative Examples 1 to 4, respectively.

[Evaluation items and evaluation methods]

The evaluation items and evaluation methods of the obtained pressure-sensitive adhesive and pressure-sensitive adhesive sheet are as follows.

(Re-peelability)

The obtained adhesive sheet was prepared in a size of 25 mm in width and 100 mm in length, and was used as a measurement sample. Then, in an atmosphere of 23°C -50%RH, the release sheet was peeled from the measurement sample, the exposed adhesive layer was adhered to a caustic soda glass plate, and a 2 kg roll was reciprocated once and pressed. Then, it left to stand for 24 hours under the conditions of 60 degreeC -90%RH. Then, after air-cooling in an atmosphere of 23°C-50%RH for 30 minutes, according to JISZ0237, a tensile tester (manufactured by Tensilon: ORIENTEC Co., Ltd.) was used, and a peeling rate of 300 mm/min, a peeling angle of 180 The adhesive strength was measured under the conditions of °. In addition, those with low adhesive strength are easy to peel again. The evaluation criteria are as follows.

◎: Less than 200mN/25 mm. rainfall.

O: 200mN/25 mm or more and 500 mN/25 mm or more. Good.

△: 500mN/25 mm or more and less than 1000 mN/25mm. Practical.

X: 1000mN/25 mm sec. Impractical.

(Wetability)

The obtained adhesive tape was prepared in a size of 50 mm in width and 100 mm in length, and was used as a measurement sample. Then, after leaving to stand for 30 minutes in a 23 degreeC-50%RH atmosphere, the release sheet was peeled from a measurement sample. While holding both ends of the adhesive tape with both hands, the center of the exposed adhesive layer was brought into contact with the glass plate, and both hands were removed. The wettability of the pressure-sensitive adhesive was evaluated by measuring the time until the entire pressure-sensitive adhesive layer adhered to the glass plate with the self-weight of the measurement sample. Since the shorter the time until contact with the glass plate is made, the better the wettability (affinity) to the glass is, and therefore the glass can be better protected by a manufacturing process using glass. The evaluation criteria are as follows.

◎: Less than 3 seconds until close contact. rainfall.

O: 3 seconds or more and less than 5 seconds until close contact. Good.

△: 5 seconds or more and less than 8 seconds until close contact. Practical.

X: 8 seconds or more until close contact. Impractical.

(Curved aptitude)

The obtained adhesive tape was prepared in a size of 25 mm in width and 40 mm in length, and was used as a measurement sample. Then, in an atmosphere of 23° C. 50% RH, the release liner was peeled off, and an adhesive tape sample was adhered to the exposed adhesive layer along the circumference of a cylinder made of polypropylene (diameter 30 mm). After 3 days, the degree of adhesion of the measurement sample to the cylinder was visually observed. The evaluation criteria are as follows.

◎: There is no floating at the end of the measurement sample. rainfall.

O: The end of the measurement sample is 1 mm or less floating. Good.

△: The end of the measurement sample floats more than 1 mm and less than 3 mm. Practical.

X: The end of the measurement sample floats beyond 3 mm. Impractical.

(productivity)

Except having replaced the coating speed of Example 1 with 30 m/min, the pressure-sensitive adhesive sheet performed in the same manner as in Example 1 was produced, and curability by high-speed coating was evaluated. In the evaluation, the adhesive layer after completion of the drying process was in contact with a finger, and the degree of curing was evaluated as stickiness.

◎: Almost never feels sticky. rainfall.

O: There is a slight stickiness, but it does not collapse even if the coating film is pressed with a finger. Good.

△: There is stickiness, but there is a feeling of moving slightly when the coating film is pressed with a finger. Practical.

X: The stickiness is severe, and the coating film collapses when touched. Impractical.

The urethane urea resin having a narrow molecular weight dispersion could be synthesized by gradually increasing the temperature of the reaction solution after dropping the amine compound from the substrate of the synthesis example over time at a relatively low temperature condition. The pressure-sensitive adhesive for surface protection of the present application using this urethane urea resin has wettability and re-peelability from the results of Tables 2 and 3, has good curved surface aptitude, and has high productivity.

Claims (8)

With respect to 100 parts by mass of the urethane urea resin (A), which is a reaction product of the isocyanate group-containing urethane prepolymer (a) and the amine compound (b), more than 3 parts by mass of the isocyanate curing agent (B) and 20 parts by mass or less,
It contains an antistatic agent (E), which is an ionic liquid that exhibits the properties of a liquid at 25°C, and the amount of the antistatic agent (E) is 0.01 to 10 parts by mass per 100 parts by mass of the urethane urea resin (A),
The urethane urea resin (A) has a primary hydroxyl group, and has a molecular weight dispersion of 1.5 to 3.1, a pressure-sensitive adhesive for surface protection.
The method of claim 1,
The urethane urea resin (A) has a weight average molecular weight of 30,000-250,000, a pressure-sensitive adhesive for surface protection.
The method according to claim 1 or 2,
A pressure-sensitive adhesive for surface protection, further comprising a plasticizer (C).
The method of claim 3,
An adhesive for surface protection comprising 0.1 to 100 parts by mass of the plasticizer (C) with respect to 100 parts by mass of the urethane urea resin (A).
The method according to claim 1 or 2,
An adhesive for surface protection, further comprising an antioxidant (D).
delete The method according to claim 1 or 2,
A pressure-sensitive adhesive for surface protection that is attached to a curved surface in an atmosphere of 23°C·50%RH and left to stand for 3 days and then floats to less than 1mm at the end.
Substrate, and
A pressure-sensitive adhesive sheet provided with an adhesive layer which is a cured product of the pressure-sensitive adhesive for surface protection according to claim 1 or 2.