JP6855743B2 - Adhesives and adhesive sheets - Google Patents

Description

The present invention relates to pressure-sensitive adhesives and pressure-sensitive adhesive sheets.

Conventionally, as a surface protection sheet for various members, an adhesive sheet in which an adhesive layer is formed on a base material sheet has been widely used. Examples of the pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive. Acrylic adhesives have excellent adhesive strength, but because of their strong adhesive strength, they do not have good re-peelability after being attached to an adherend. In particular, after a lapse of time in a high-temperature and high-humidity environment, the re-peelability is further reduced due to the increase in adhesive strength, and the adhesive tends to remain on the surface of the adherend after re-peeling. .. Silicone adhesives tend to contaminate the adherend, and silicone resins with relatively low molecular weight may volatilize and adsorb to the surface of devices such as electronic devices, causing problems. On the other hand, the urethane-based adhesive has good adhesion to the adherend, has relatively excellent removability, and is difficult to volatilize.

Patent Document 1 discloses a urethane-based pressure-sensitive adhesive in which a polyfunctional isocyanate compound is blended with a polyurethane polyol obtained by reacting a polyester polyol, a polyether polyol, and an organic polyisocyanate in the presence of two types of catalysts. (Claim 1). It is described that this urethane-based pressure-sensitive adhesive has good removability after being left on the adherend under the condition of 40 ° C.-65% RH (paragraph 0051 and Table 2). Examples 1-6 etc.).
In the present specification, "RH" indicates relative humidity unless otherwise specified.

Patent Document 2 discloses a urethane-based pressure-sensitive adhesive containing a polyurethane polyol, a polyfunctional isocyanate compound, and a fatty acid ester having 10 to 30 carbon atoms (claim 1). It is described that this urethane-based pressure-sensitive adhesive has good removability after being left on the adherend under the condition of 40 ° C.-80% RH for 24 hours (paragraphs 0049 and Table 1). Examples 1 to 4 etc.).

Patent Document 3 discloses a urethane-based pressure-sensitive adhesive containing a polyurethane polyol, a polyfunctional isocyanate compound, and at least one compound selected from a polyalkylene glycol-based compound, an epoxy-based compound, and a phosphoric acid ester-based compound. (Claim 1). It is described that this urethane-based pressure-sensitive adhesive has good removability after being left on the adherend under the condition of 60 ° C.-90% RH for 96 hours (paragraph 0061 and Table 1). Examples 1 to 18 etc.).

In addition, there is Patent Document 4 as a related document of the present invention. The contents of this document will be described later.

Japanese Unexamined Patent Publication No. 2000-73040 Japanese Unexamined Patent Publication No. 2011-190420 Japanese Unexamined Patent Publication No. 2015-7226 Japanese Unexamined Patent Publication No. 2011-74333

Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (OELDs), and touch panel displays that combine such flat panel displays and touch panels are used for televisions, personal computers (PCs), mobile phones, and mobile information. Widely used in electronic devices such as terminals.
Urethane-based adhesive sheets are suitably used as surface protective sheets for flat panel displays and touch panel displays, as well as substrates and optical members manufactured or used in these manufacturing processes.
The range of use of the above electronic devices is expanding, and there is a possibility that they will be placed in a hot and humid environment that is harsher than before.

In the pressure-sensitive adhesive sheet, it is important that the pressure-sensitive adhesive layer has good adhesion to the base material sheet (also referred to as base material adhesion).
Further, conventionally, polyethylene terephthalate (PET) sheet is mainly preferably used as a base sheet from the viewpoint of the adhesion of the pressure-sensitive adhesive layer to the base material and the ease of coating the pressure-sensitive adhesive, but in recent years, polypropylene is cheaper. The use of (PP) sheets is also being considered. In general, the adhesion of the urethane-based adhesive layer to the base material of the urethane-based adhesive layer to the PP sheet, which is a relatively low-polarity base material, tends to be inferior to that of the base material adhesion of the urethane-based adhesive layer to the PET sheet. Further, regardless of the type of the base material sheet, there is a possibility that higher base material adhesion will be required in the future due to the expansion of the range of use of the electronic device.

In a display such as OELD, it is possible to make it flexible by using a plastic film as a substrate. In such an application, it is preferable that the adhesive layer does not peel off from the base sheet even when the structure in which the adhesive sheet is attached to the flexible adherend is repeatedly curved, and has good curvature.

The present invention has been made in view of the above circumstances, and is a pressure-sensitive adhesive capable of forming a pressure-sensitive adhesive layer having good removability even when placed in a harsher high-temperature and high-humidity environment than before. It is an object of the present invention to provide an adhesive sheet using this.
Another object of the present invention is to provide a pressure-sensitive adhesive having good adhesion to a base material and a pressure-sensitive adhesive sheet using the same.
Another object of the present invention is to provide a pressure-sensitive adhesive having good curvature and a pressure-sensitive adhesive sheet using the same.

The first pressure-sensitive adhesive of the present invention is
One or more polyurethane polyols (AX) which are copolymer reaction products of one or more first polyols (x) having a number average molecular weight (Mn) of more than 300 and one or more organic polyisocyanates (y). )When,
With one or more polyfunctional isocyanate compounds (B),
It contains one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less.

The first pressure-sensitive adhesive of the present invention is a composition containing a plurality of kinds of materials including the above-mentioned components (AX), (B) and (C). , (C) may not all be clearly present as independent ingredients. That is, when the first pressure-sensitive adhesive of the present invention contains a reaction product obtained by partially reacting a plurality of types of compounding components including the components (AX), (B), and (C). There is also.

The second pressure-sensitive adhesive of the present invention is
One or more first polyols (x) having a number average molecular weight (Mn) of more than 300, one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less, and one or more One or more polyurethane polyols (AY), which are copolymer reaction products with the organic polyisocyanate (y),
Contains one or more polyfunctional isocyanate compounds (B).

The second pressure-sensitive adhesive of the present invention is a composition containing a plurality of types of materials containing the above components (AY) and (B), and the plurality of types containing the components (AY) and (B) in the pressure-sensitive adhesive. In some cases, all of the ingredients in the above are not clearly present as independent ingredients. That is, the pressure-sensitive adhesive of the present invention may contain a reaction product obtained by partially reacting a plurality of types of compounding components including the components (AY) and (B).

The pressure-sensitive adhesive sheet of the present invention includes a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the first or second pressure-sensitive adhesive of the present invention described above.

In the present specification, "Mw" is a polystyrene-equivalent weight average molecular weight determined by gel permeation chromatography (GPC) measurement. "Mn" is a polystyrene-equivalent number average molecular weight determined by GPC measurement. These can be measured by the method described in the [Examples] section.

According to the present invention, there is provided an adhesive capable of forming an adhesive layer having good removability even when placed in a high temperature and high humidity environment harsher than the conventional one, and an adhesive sheet using the same. can do.
According to the present invention, it is also possible to provide a pressure-sensitive adhesive having good adhesion to a base material and a pressure-sensitive adhesive sheet using the same.
According to the present invention, it is also possible to provide a pressure-sensitive adhesive having good curvature and a pressure-sensitive adhesive sheet using the same.

It is a schematic cross-sectional view of the pressure-sensitive adhesive sheet of 1st Embodiment which concerns on this invention. It is a schematic cross-sectional view of the pressure-sensitive adhesive sheet of the 2nd Embodiment which concerns on this invention.

[First and second adhesives]
The first and second pressure-sensitive adhesives of the present invention are urethane-based pressure-sensitive adhesives containing one or more types of polyurethane polyols (A) and one or more types of polyfunctional isocyanate compounds (B).

The first pressure-sensitive adhesive of the present invention is one or more kinds of polyurethane polyols (A), one or more kinds of first polyols (x) having a number average molecular weight (Mn) of more than 300, and one or more kinds of organic polys. One or more polyurethane polyols (AX), which are copolymer reaction products with isocyanate (y), were used, and one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less were added. It is an adhesive.

The second pressure-sensitive adhesive of the present invention is one or more kinds of polyurethane polyols (A), one or more kinds of first polyols (x) having a number average molecular weight (Mn) of more than 300, and a number average molecular weight (Mn). Adhesive using one or more polyurethane polyols (AY) which is a copolymerization reaction product of one or more second polyols (C) and one or more organic polyisocyanates (y) having a value of 300 or less. Is.

"First adhesive"
The first pressure-sensitive adhesive of the present invention is
One or more polyurethane polyols (AX) which are copolymer reaction products of one or more first polyols (x) having a number average molecular weight (Mn) of more than 300 and one or more organic polyisocyanates (y). )When,
With one or more polyfunctional isocyanate compounds (B),
It contains one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less.

(Polyurethane polyol (AX))
The polyurethane polyol (AX) is a reaction product obtained by copolymerizing one or more first polyols (x) with one or more organic polyisocyanates (y). The copolymerization reaction can be carried out in the presence of one or more catalysts, if necessary. If necessary, one or more kinds of solvents can be used for the copolymerization reaction.

<First polyol (x)>
The first polyol (x) is a polyol having a number average molecular weight (Mn) of more than 300. The type of the first polyol (x) is not particularly limited, and examples thereof include polyester polyols, polyether polyols, and combinations thereof.

As the polyester polyol, known ones can be used.
Examples of the polyester polyol include a compound (esterified product) obtained by an esterification reaction between one or more polyol components and one or more acid components.

As the polyol component of the raw material, ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 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-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, and hexanetriol. And so on.

The acid components of the raw material include succinic acid, methylsuccinic acid, adipic acid, piceric acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1, 4-Cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid , And these acid anhydrides and the like.

In addition to the above, the polyester polyol is a compound (ring-opening polymer) obtained by ring-opening polymerization of one or more lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone. ) Is also mentioned.

The number average molecular weight (Mn) of the polyester polyol is not particularly limited, and is preferably more than 300 to 8,000, more preferably 400 to 7,000, and particularly preferably 500 to 6,000. When Mn is more than 300, the reactivity becomes suitable, and the polymerization reaction stability of the polyurethane polyol (AX) is further improved. When Mn is 8,000 or less, the cohesive force of the polyurethane polyol (AX) becomes suitable.

As the polyether polyol, known ones can be used.
Examples of the polyether polyol include a compound (addition polymer) obtained by addition-polymerizing one or more kinds of oxylan compounds using an active hydrogen-containing compound having two or more active hydrogens in one molecule as an initiator. ..

Examples of the initiator include hydroxyl group-containing compounds and amines. Specifically, 2 such as ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, neopentyl glycol, butylethylpentanediol, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine. Functional initiators; trifunctional initiators such as glycerin, trimethylolpropane, and triethanolamine; tetrafunctional initiators such as pentaerythritol, ethylenediamine, and aromatic diamines; pentafunctional initiators such as diethylenetriamine and the like.

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

As the polyether polyol, an alkylene oxide adduct (also referred to as “polyoxyalkylene polyol”) of an active hydrogen-containing compound is preferable. Of these, bifunctional polyether polyols such as polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol; trifunctional polyether polyols such as an alkylene oxide adduct of glycerin, and the like are preferable.

The number average molecular weight (Mn) of the polyether polyol is not particularly limited, and is preferably more than 300 to 8,000, more preferably 400 to 7,000, and particularly preferably 500 to 4,000. When Mn is more than 300, the reactivity becomes suitable and the gelation of the polyurethane polyol (AX) is effectively suppressed. When Mn is 8,000 or less, the cohesive force of the polyurethane polyol (AX) becomes suitable.

As one or more kinds of first polyols (x), one or more kinds of bifunctional polyols (x1) and one or more kinds of trifunctional polyols (x2) can be used in combination.
The bifunctional polyol (x1) has two-dimensional crosslinkability and can impart appropriate flexibility to the adhesive layer. The trifunctional polyol (x2) has three-dimensional crosslinkability and can impart appropriate hardness to the adhesive layer. By using these in combination, it tends to be easy to obtain an adhesive layer having suitable cohesive force and adhesive force.

When the total amount of one or more types of bifunctional polyols (x1) and one or more types of trifunctional polyols (x2) is 100 parts by mass.
More preferably, the amount of one or more bifunctional polyols (x1) is 1 to 40 parts by mass, and the amount of one or more trifunctional polyols (x2) is 99 to 60 parts by mass.
More preferably, the amount of one or more bifunctional polyols (x1) is 1 to 30 parts by mass, and the amount of one or more trifunctional polyols (x2) is 99 to 70 parts by mass.
More preferably, the amount of one or more bifunctional polyether polyols (x1) is 5 to 15 parts by mass, and the amount of one or more trifunctional polyether polyols (x2) is 95 to 85 parts by mass.

<Organic polyisocyanate (y)>
Known organic polyisocyanate compounds (y) can be used, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

Examples of the aromatic polyisocyanate include 1,3-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, and 2,6-triisocyanate. Range isocyanate, 4,4'-toluidin diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4', 4 "-Triphenylmethane triisocyanate, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4-diisocyanate, 1, , 4-Tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.

Aliphatic polyisocyanates include 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.

Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate, 1,3-cyclopentanediisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, and methyl-2,4. -Cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatemethyl) cyclohexane, 1,4-bis (isocyanatemethyl) cyclohexane and the like can be mentioned. ..

In addition, examples of the polyisocyanate include a trimethylolpropane adduct form, a biuret form, and a trimer of the above-mentioned polyisocyanate (the trimer contains an isocyanurate ring) and the like.

As the polyisocyanate (y), 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate) and the like are preferable.

<Catalyst>
Known catalysts can be used, and examples thereof include tertiary amine compounds and organometallic compounds.

Examples of the tertiary amine compound include triethylamine, triethylenediamine, 1,8-diazabicyclo (5,4,0) -undecene-7 (DBU) and the like.

Examples of the organometallic compound include tin-based compounds and non-tin-based compounds.
Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimalate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, and tributyltin acetate. , Triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, tin 2-ethylhexanoate and the like.
Non-tin compounds include titanium-based compounds such as dibutyltitanium dichloride, tetrabutyl titanate, and butoxytitanium trichloride; lead-based compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; 2 -Iron-based such as iron ethylhexanoate and iron acetylacetonate; cobalt-based such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc-based such as zinc naphthenate and zinc 2-ethylhexanoate; Examples include zirconium.

One kind or two or more kinds of catalysts can be used.
When a plurality of first polyols (x) having different reactivity are used in combination, the difference in reactivity may cause poor polymerization stability or white turbidity of the reaction solution in a single catalyst system. .. In this case, by using two or more kinds of catalysts, the reaction (for example, reaction rate) can be easily controlled, and the above problem can be solved. In a system in which a plurality of types of first polyols (x) having different reactivity are used in combination, it is preferable to use two or more types of catalysts. The combination of two or more kinds of catalysts is not particularly limited, and examples thereof include tertiary amine / organometallic, tin-based / non-tin-based, and tin-based / tin-based. It is preferably tin-based / tin-based, more preferably dibutyltin dilaurate and tin 2-ethylhexanoate.
The mass ratio of tin 2-ethylhexanoate to dibutyltin dilaurate (tin 2-ethylhexanoate / dibutyltin dilaurate) is not particularly limited, and is preferably more than 0 and less than 1, more preferably 0.2 to 0.6. is there. When the mass ratio is less than 1, the balance of catalytic activity is good, gelation and white turbidity of the reaction solution are effectively suppressed, and the polymerization stability is further improved.

The amount of one or more catalysts used is not particularly limited, and is preferably 0.01 to 0.01 with respect to the total amount of one or more first polyols (x) and one or more organic polyisocyanates (y). It is 1.0% by mass.

<Solvent>
If necessary, one or more kinds of solvents can be used for the polymerization of the polyurethane polyol (AX). Known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene and the like are particularly preferable from the viewpoint of the solubility of the polyurethane polyol (AX) and the boiling point of the solvent.

<Polymerization method>
The polymerization method of the polyurethane polyol (AX) is not particularly limited, and known polymerization methods such as a massive polymerization method and a solution polymerization method can be applied.
The polymerization procedure is not particularly limited.
Procedure 1) One or more first polyols (x), one or more organic polyisocyanates (y), one or more catalysts if necessary, and one or more solvents as needed. Procedure for filling in a flask;
Step 2) One or more first polyols (x), one or more catalysts if necessary, and one or more solvents if necessary are placed in a flask, and one or more organic polyisosianates are charged therein. Examples thereof include a procedure in which (y) is added dropwise.
Procedure 2) is preferable because the reaction can be easily controlled.

When a catalyst is used, the reaction temperature is preferably less than 100 ° C, more preferably 85 to 95 ° C. When the reaction temperature is 100 ° C. or higher, it becomes difficult to control the reaction rate, polymerization stability, etc., and it may be difficult to produce a polyurethane polyol (AX) having a desired molecular weight.
The reaction temperature when no catalyst is used is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. The reaction time when no catalyst is used is preferably 3 hours or more.

The weight average molecular weight (Mw) of the polyurethane polyol (A) is preferably 10,000 to 500,000, more preferably 30,000 to 400,000, and particularly preferably 50,000 to 350,000. When the Mw of the polyurethane polyol (A) is in an appropriate range, good coatability can be easily obtained. The molecular weight dispersion (Mw / Mn) is preferably 1 to 15, more preferably 4 to 12.

(Polyfunctional isocyanate compound (B))
As the polyfunctional isocyanate compound (B), a known compound can be used, and the compound exemplified as the organic polyisocyanate (y) which is a raw material of the polyurethane polyol (AX) (specifically, aromatic polyisocyanate, aliphatic polyisocyanate). , Aromatic aliphatic polyisocyanates, alicyclic polyisocyanates, and trimethylolpropane adducts / burettes / trimerics thereof) can be used.

(Second polyol (C))
The second polyol (C) is a polyol having a number average molecular weight (Mn) of 300 or less. Examples of the second polyol (C) include ethylene glycol (EG), propylene glycol (PG), diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-. Pentandiol, 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-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, And hexanetriol and the like.
The second polyol (C) having a plurality of hydroxyl groups and having a relatively small molecular weight can be water-soluble, and is preferably water-soluble.
In the present specification, “having water solubility” specifically means that the solubility in water at 25 ° C. is 0.1 g / 100 gH ₂ O or more, preferably 0.5 g / 100 gH ₂ O or more. , More preferably 1 g / 100 gH ₂ O or more.

Generally, when a structure in which an adhesive sheet is attached to an adherend is exposed to a high-temperature and high-humidity environment, the re-peelability decreases due to an increase in the adhesive strength of the adhesive layer, and the surface of the adherend after re-peeling. Adhesive remains on the surface. Adhesive contamination may occur.
The first pressure-sensitive adhesive of the present invention containing the second polyol (C) can form a pressure-sensitive adhesive layer having good removability even when placed in a higher temperature and higher humidity environment than before. .. In order to show this, in the section of [Example] described later, the temperature and humidity conditions for the removability evaluation are set more severely than those of Patent Documents 1 to 3 mentioned in the section of "Background Technology".

The mechanism of the above-mentioned action and effect is not always clear, but the present inventors speculate as follows.
In general, since the removability of the adhesive layer does not decrease in a high-temperature drying environment, it is presumed that the decrease in the removability of the adhesive layer is due to moisture. By adding a second polyol (C) having a plurality of hydroxyl groups, having a relatively small molecular weight, and having a relatively high hydrophilicity to the pressure-sensitive adhesive, a large number of highly hydrophilic urethane bonds are formed when the pressure-sensitive adhesive layer is formed. It can be formed (formed at high density), and it is presumed that the hydrophilicity of the adhesive layer is improved. As a result, the transfer of moisture between the adhesive layer and the external environment is likely to occur, and even if the moisture invades the adhesive layer from the outside, the moisture is likely to be discharged from the adhesive layer to the external environment, and the moisture in the adhesive layer is likely to occur. It is presumed that the amount of water can be kept relatively low and it is less susceptible to the influence of water.

Further, although the reason is not clear, by adding a second polyol (C) having a plurality of hydroxyl groups, having a relatively small molecular weight, and having a relatively high hydrophilicity to the pressure-sensitive adhesive, the base material of the pressure-sensitive adhesive layer is formed. The effect of improving adhesion can also be obtained. In particular, since the first pressure-sensitive adhesive of the present invention improves the adhesion to the base material, the second polyol (C) having a relatively small molecular weight, the polyfunctional isocyanate compound (B), or a reaction product thereof can be used as the base material. It is presumed that the anchorability to the base material will be improved and the adhesion to the base material will be improved.
The first pressure-sensitive adhesive of the present invention can form a pressure-sensitive adhesive layer having excellent substrate adhesion to both PET sheets and relatively low-polarity substrates such as PP sheets. Therefore, the first pressure-sensitive adhesive of the present invention is preferable because it has a high degree of freedom in selecting the base sheet to be used. For example, the cost of the adhesive sheet can be reduced by using an inexpensive PP sheet or the like.

Further, although the reason is not clear, the addition of the second polyol (C) to the pressure-sensitive adhesive has the effect of improving the flexibility of the pressure-sensitive adhesive layer and improving the curvature. In particular, since the second pressure-sensitive adhesive of the present invention has improved curvability, the second polyol (C) having a relatively small molecular weight in the polyurethane polyol (AY) has a urethane bond portion (also referred to as a hard segment) having a strong cohesive force. ) Is reduced and the adhesive layer is softened.
In a display such as OELD, flexibility can be achieved by using a plastic film as a substrate. When the first pressure-sensitive adhesive of the present invention is used, peeling of the pressure-sensitive adhesive layer from the base material sheet is effectively suppressed even when the structure in which the pressure-sensitive adhesive sheet is attached to a flexible adherend is repeatedly curved. To.

The pressure-sensitive adhesive layer is made of a cured product of the pressure-sensitive adhesive, and it is presumed that the second polyol (C) reacts with the polyfunctional isocyanate compound (B) and is incorporated into the polymer network during the curing process of the pressure-sensitive adhesive. .. By incorporating the second polyol (C) component into the polymer network of the adhesive layer, the above-mentioned action effect of the adhesive layer (effect of improving removability when placed in a high temperature and high humidity environment, effect of improving substrate adhesion) It is presumed that the improving effect and the effect of improving the curvature) will be exhibited.

Since the above-mentioned effects of the adhesive layer (effect of improving re-peelability when placed in a high-temperature and high-humidity environment, effect of improving substrate adhesion, and effect of improving curvature) are effectively exhibited, the second The polyol (C) in the above is preferably a monomer.

Since the above-mentioned effects of the adhesive layer (effect of improving re-peelability when placed in a high-temperature and high-humidity environment, effect of improving substrate adhesion, and effect of improving curvature) are effectively exhibited, the second The number average molecular weight (Mn) of the polyol (C) is 300 or less, preferably 60 to 200, and more preferably 70 to 150.

As a related document of the present invention, there is Patent Document 4 listed in the section of "Background Art". This document discloses a urethane-based pressure-sensitive adhesive using a bifunctional aliphatic polyisocyanate compound and a trifunctional or higher functional aliphatic polyisocyanate compound as the polyisocyanate compound (claim 1). Patent Document 4 lists short-chain monools having a molecular weight of 300 or less as a raw material for a bifunctional aliphatic polyisocyanate compound (claim 2). As the trifunctional or higher functional aliphatic polyisocyanate compound, a short-chain diol having a molecular weight of 300 or less is mentioned (claim 3).
Unlike the present invention, in Patent Document 4, a short-chain monool having a molecular weight of 300 or less and a short-chain diol having a molecular weight of 300 or less are "raw materials for producing a polyisocyanate compound as a curing agent" and are components of a pressure-sensitive adhesive. It was not added as. Nor is it a raw material polyol for polyurethane polyols.

(Plasticizer (P))
Since the wettability can be improved, the first pressure-sensitive adhesive of the present invention can further contain one or more plasticizers (P). Examples of the plasticizer (P) include a fatty acid ester-based plasticizer, a polyether ester-based plasticizer, a hydroxycarboxylic acid ester-based plasticizer, and a phosphoric acid ester-based plasticizer.

Examples of the fatty acid ester include an ester of a monobasic acid or polybasic acid having 6 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms, and an unsaturated fatty acid or branched acid having 14 to 18 carbon atoms and an alcohol having 4 or less valences. Examples thereof include esters and esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms and polyalkylene glycols.

Examples of the ester of a monobasic acid or polybasic acid having 6 to 18 carbon atoms and a branched alcohol having 18 or less carbon atoms include isostearyl laurate, isopropyl myristate, isosetyl myristate, octyldodecyl myristate, and isostearyl palmitate. Examples thereof include isocetyl stearate, octyldodecyl oleate, diisostearyl adipate, diisocetyl sebacate, trioleyl trimeritate, and triisocetyl trimeritate.

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

Examples of the polyether ester-based plasticizer include polyethylene glycol dihexylate, polyethylene glycol di-2-ethylhexylate, polyethylene glycol dilaurate, polyethylene glycol dioleate, and dipolyethylene glycol methyl ether adipate.

The plasticizer (P) may be a compound containing a fatty acid ester structure and a polyether structure, such as polyoxyethylene ether of a sorbitan fatty acid ester obtained by condensing ethylene oxide with a sorbitan fatty acid ester. For example, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monooleate and the like can be mentioned.

Examples of the hydroxycarboxylic acid ester-based plasticizer include butyl citrate, triethyl citrate, tripropyl citrate, and triethyl o-acetyl citrate.

Examples of the phosphoric acid ester-based plasticizer include tributyl phosphate, tris (2-ethylhexyl) phosphate, triphenyl phosphate, and tricresyl phosphate.

The number average molecular weight (Mn) of the plasticizer (P) is not particularly limited, and is preferably 200 to 1,000, more preferably 230 to 900, still more preferably 250 to 800, particularly preferably, from the viewpoint of improving the wetting rate and the like. Is 250-500.

(solvent)
The first pressure-sensitive adhesive of the present invention may contain one or more kinds of solvents, if necessary. Known solvents can be used, and examples thereof include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Ethyl acetate, toluene and the like are particularly preferable from the viewpoint of the solubility of the polyurethane polyol (AX) and the boiling point of the solvent.

(Other optional ingredients)
The first pressure-sensitive adhesive of the present invention may contain one or more other optional components, if necessary, as long as the effects of the present invention are not impaired. Other optional components include catalysts, resins other than urethane resins, fillers, metal powders, pigments, foils, softeners, conductive agents, antioxidants, UV absorbers, light stabilizers, surface lubricants. Examples thereof include agents, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, antifoaming agents, lubricants and the like.

Examples of the filler include talc, calcium carbonate, titanium oxide and the like.

Examples of the antioxidant (I) include radical chain inhibitors such as phenolic antioxidants; peroxide decomposition agents such as sulfur-based antioxidants and phosphorus-based antioxidants.

As a phenolic antioxidant,
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stea-β- (3,5-di-t-butyl-). 4-Hydroxyphenyl) Monophenolic antioxidants such as 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'-hydroxybenzyl) -S-triazine- Examples thereof include high molecular weight phenolic antioxidants such as 2,4,6- (1H, 3H, 5H) trione and tocophenol.

Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate.

Examples of the phosphorus-based antioxidant include triphenylphosphine, diphenylisodecylphosphine, phenyldiisodecylphosphine and the like.

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

Examples of benzophenone-based ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 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) Examples include methane.

Examples of the benzotriazole-based ultraviolet absorber include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, and 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",-Tetrahydrophthalimidemethyl)- 5'-Methylphenyl] benzotriazole, 2,2'methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], and [2 ( 2'-Hydroxy-5'-metaacryloxyphenyl) -2H-benzotriazole and the like can be mentioned.

Examples of the salicylic acid-based ultraviolet absorber include phenylsalicylate, p-tert-butylphenylsalicylate, and p-octylphenylsalicylate.

Examples of the cyanoacrylate-based ultraviolet absorber include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate and ethyl-2-cyano-3,3'-diphenyl acrylate.

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

Hindered amine light stabilizers include [bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate], bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and Examples thereof include methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate.

Examples of the ultraviolet stabilizer include nickel bis (octylphenyl) sulfide, [2,2'-thiobis (4-tert-octylphenolate)] -n-butylamine nickel, nickel complex-3,5-di-tert-butyl-. Examples thereof include 4-hydroxybenzyl-phosphate monoethylate, nickel-dibutyldithiocarbamate, benzoate type quencher, nickel-dibutyldithiocarbamate and the like.

Examples of the leveling agent include an acrylic leveling agent, a fluorine-based leveling agent, and a silicone-based leveling agent. As an acrylic leveling agent, Polyflow No. 36, Polyflow No. 56, Polyflow No. 85HF, Polyflow No. 99C (manufactured by Isuremo Kyoeisha Chemical Co., Ltd.) and the like can be mentioned. Examples of the fluorine-based leveling agent include Megafuck F470N and Megafuck F556 (both manufactured by DIC Corporation). Examples of the silicone-based leveling agent include Grandic PC4100 (manufactured by DIC Corporation) and the like.

(Mixing ratio)
The first pressure-sensitive adhesive of the present invention contains one or more polyurethane polyols (AX), one or more polyfunctional isocyanate compounds (B), and one or more second polyols (C) as essential components. Further, if necessary, one or more kinds of plasticizers (P) are contained. These compounding ratios are not particularly limited, but preferable compounding ratios are as follows.

The amount of one or more polyfunctional isocyanates (B) with respect to 100 parts by mass of one or more polyurethane polyols (AX) is preferably 1 to 20 parts by mass, and more preferably 5 to 15 parts by mass. When the amount of one or more types of polyfunctional isocyanate (B) is 1 part by mass or more, the cohesive force of the adhesive layer is good, and when it is 20 parts by mass or less, the adhesive force of the adhesive layer is good.

The amount of one or more second polyols (C) with respect to 100 parts by mass of one or more polyurethane polyols (AX) is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass. ..
When the amount of the second polyol (C) of one or more kinds is 0.1 to 10 parts by mass, the hydrophilicity of the adhesive layer becomes suitable, and the invasion and discharge of water when placed in a high temperature and high humidity environment The balance is improved, and the action effect of the adhesive layer by the addition of the second polyol (C) (the effect of improving the removability when placed in a high temperature and high humidity environment, the effect of improving the adhesion to the base material, and the curvability (Improvement effect) is effectively expressed. Further, when the amount of the second polyol (C) of one or more kinds is 10 parts by mass or less, the amount of the polyurethane polyol (AX) which is the main active ingredient of the originally required adhesive is sufficiently secured, and the adhesive The required performance is ensured.

The amount of one or more plasticizers (P) with respect to 100 parts by mass of one or more polyurethane polyols (AX) is preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass. When the amount of one or more plasticizers (P) is 10 parts by mass or more, the effect of adding the plasticizer (P) (the effect of improving wettability) can be effectively exhibited. When the amount of one or more plasticizers (P) is 70 parts by mass or less, the amount of polyurethane polyol (AX), which is the main active ingredient of the originally required adhesive, is sufficiently secured, and the performance required as an adhesive is sufficient. Is secured.

(Manufacturing method of the first adhesive)
The method for producing the first pressure-sensitive adhesive of the present invention is not particularly limited.
The method for producing the first pressure-sensitive adhesive according to the first aspect of the present invention is
One or more first polyols (x) having a number average molecular weight (Mn) of more than 300 are copolymerized with one or more organic polyisocyanates (y) to obtain one or more polyurethane polyols (AX). And the process of obtaining
One or more kinds of polyfunctional isocyanate compounds (B) and one or more kinds of second polyols (C) having a number average molecular weight (Mn) of 300 or less are mixed with one or more kinds of polyurethane polyols (AX). Has a step to do.

"Second adhesive"
The second pressure-sensitive adhesive of the present invention is
One or more first polyols (x) having a number average molecular weight (Mn) of more than 300, one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less, and one or more One or more polyurethane polyols (AY), which are copolymer reaction products with the organic polyisocyanate (y),
Contains one or more polyfunctional isocyanate compounds (B).

The first polyol (x), the second polyol (C), the organic polyisocyanate (y), and the polyfunctional isocyanate compound (B) are the same as these materials used in the first pressure-sensitive adhesive of the present invention, respectively. Is.

In the first pressure-sensitive adhesive of the present invention, one or more second polyols (C) are added to one or more kinds of polyurethane polyols (AX), whereas in the second pressure-sensitive adhesive of the present invention, one or more kinds of second polyols (C) are added. One or more raw material polyols of polyurethane polyol (AY) include one or more second polyols (C). That is, the polyurethane polyol (AY) is obtained by copolymerizing one or more first polyols (x), one or more second polyols (C), and one or more organic polyisocyanates (y). The resulting reaction product. The copolymerization reaction can be carried out in the presence of one or more catalysts, if necessary. If necessary, one or more kinds of solvents can be used for the copolymerization reaction. The catalyst and solvent that can be used are the same as the polyurethane polyol (AX) used in the first pressure-sensitive adhesive of the present invention.

The second pressure-sensitive adhesive of the present invention can have the same effect as the first pressure-sensitive adhesive of the present invention.
That is, the second pressure-sensitive adhesive of the present invention can form a pressure-sensitive adhesive layer having good removability even when placed in a higher temperature and higher humidity environment than before. In addition, it is possible to form an adhesive layer having improved substrate adhesion and improved curvature.
The adhesive layer is made of a cured product of the adhesive, and like the first adhesive of the present invention, the second polyol (C) component is incorporated into the polymer network of the adhesive layer, so that the adhesive layer is placed in a high temperature and high humidity environment. It is presumed that the effect of improving the removability when scratched, the effect of improving the adhesion to the base material, and the effect of improving the curvature are exhibited. As described above, the second pressure-sensitive adhesive of the present invention is particularly excellent in curvability.

The preferred embodiment (type and number average molecular weight (Mn)) of the second polyol (C) is the same as that of the first pressure-sensitive adhesive of the present invention.
The amount of one or more second polyols (C) relative to 100 parts by mass of the total amount of the raw material polyol of the polyurethane polyol (AY) is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass. is there. When the amount of one or more second polyols (C) is 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the raw material polyols of the polyurethane polyol (AY), the hydrophilicity of the adhesive layer becomes preferable and the temperature is high. The balance between the ingress and discharge of water when placed in a moist environment is improved, and the action and effect of the adhesive layer due to the addition of the second polyol (C) (improvement of removability when placed in a high temperature and high humidity environment). The effect, the effect of improving the adhesion to the base material, and the effect of improving the curvature) are effectively exhibited. Further, if the amount of one or more second polyols (C) is 10 parts by mass or less with respect to 100 parts by mass of the total amount of the raw material polyols of the polyurethane polyol (AY), the first polyol originally required for the characteristics of the pressure-sensitive adhesive. A sufficient amount of (x) is secured, and the performance required as an adhesive is ensured.

<Polymerization method>
The polymerization procedure of the polyurethane polyol (AY) is the same as that of the polyurethane polyol (AX) used in the first pressure-sensitive adhesive of the present invention.
Procedure 1) One or more first polyols (x), one or more second polyols (C), one or more organic polyisocyanates (y), one or more catalysts as needed, and necessary Procedure for charging one or more kinds of solvents in a flask at once according to
Step 2) Put one or more first polyols (x), one or more second polyols (C), one or more catalysts if necessary, and one or more solvents if necessary into a flask. Examples thereof include a procedure of charging and adding one or more kinds of organic polyisocianates (y) in a dropping manner.
Procedure 2) is preferable because the reaction can be easily controlled.
The preferable reaction conditions (reaction temperature and reaction time) for the polymerization of the polyurethane polyol (AY) are the same as those of the polyurethane polyol (AX) used in the first pressure-sensitive adhesive of the present invention.

(Arbitrary ingredient)
Since the wettability can be improved like the first pressure-sensitive adhesive of the present invention, the second pressure-sensitive adhesive of the present invention can further contain one or more plasticizers (P).
Similar to the first pressure-sensitive adhesive of the present invention, the second pressure-sensitive adhesive of the present invention may contain one or more kinds of solvents, if necessary.
Similar to the first pressure-sensitive adhesive of the present invention, the second pressure-sensitive adhesive of the present invention contains, if necessary, one or more other optional components other than the above, as long as the effects of the present invention are not impaired. Can be done.
The plasticizer (P), solvent, and other optional components that can be used are the same as those of the first pressure-sensitive adhesive of the present invention.

(Mixing ratio)
The second pressure-sensitive adhesive of the present invention contains one or more polyurethane polyols (AY) and one or more polyfunctional isocyanate compounds (B) as essential components, and further, if necessary, one or more plasticizers (P). )including. These compounding ratios are not particularly limited, but preferable compounding ratios are as follows.

The amount of one or more polyfunctional isocyanates (B) with respect to 100 parts by mass of one or more polyurethane polyols (AY) is preferably 1 to 20 parts by mass, and more preferably 5 to 15 parts by mass. When the amount of one or more types of polyfunctional isocyanate (B) is 1 part by mass or more, the cohesive force of the adhesive layer is good, and when it is 20 parts by mass or less, the adhesive force of the adhesive layer is good.

The amount of one or more plasticizers (P) with respect to 100 parts by mass of one or more polyurethane polyols (AY) is preferably 10 to 70 parts by mass, more preferably 20 to 50 parts by mass.
When the amount of one or more plasticizers (P) is 10 parts by mass or more, the effect of adding one or more plasticizers (P) (the effect of improving wettability) can be effectively exhibited. When the amount of the plasticizer (P) is 70 parts by mass or less, the amount of the polyurethane polyol (AY), which is the main active ingredient of the adhesive, which is originally required, is sufficiently secured, and the performance required as the adhesive is ensured. ..

(Manufacturing method of the second adhesive)
The method for producing the second pressure-sensitive adhesive of the present invention is not particularly limited.
The method for producing the second pressure-sensitive adhesive according to the present invention is as follows.
One or more first polyols (x) having a number average molecular weight (Mn) of more than 300, one or more second polyols (C) having a number average molecular weight (Mn) of 300 or less, and one or more A step of copolymerizing with an organic polyisocyanate (y) to obtain one or more kinds of polyurethane polyols (AY), and
It has a step of mixing one or more kinds of polyfunctional isocyanate compounds (B) with one or more kinds of polyurethane polyols (AY).

"Third urethane adhesive"
The first pressure-sensitive adhesive of the present invention and the second pressure-sensitive adhesive of the present invention include a third pressure-sensitive adhesive of the present invention in which these pressure-sensitive adhesives are combined.
The third urethane pressure-sensitive adhesive of the present invention is
One or more polyurethane polyols (AX) which are copolymer reaction products of one or more first polyols (x) having Mn of more than 300 and one or more organic polyisocyanates (y).
With one or more polyfunctional isocyanate compounds (B),
It contains one or more second polyols (C) having Mn of 300 or less.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention includes a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the first or second pressure-sensitive adhesive of the present invention described above.
The adhesive layer can be formed on one side or both sides of the base sheet. If necessary, the exposed surface of the adhesive layer can be covered with a release sheet. The release sheet is peeled off when the adhesive sheet is attached to the adherend.

FIG. 1 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 is an adhesive sheet, reference numeral 11 is a base material sheet, reference numeral 12 is an adhesive layer, and reference numeral 13 is a release sheet. The pressure-sensitive adhesive sheet 10 is a single-sided pressure-sensitive adhesive sheet in which an pressure-sensitive adhesive layer is formed on one side of the base material sheet.
FIG. 2 shows a schematic cross-sectional view of the pressure-sensitive adhesive sheet according to the second embodiment of the present invention. In FIG. 2, reference numeral 20 is an adhesive sheet, reference numeral 21 is a base material sheet, reference numerals 22A and 22B are adhesive layers, and reference numerals 23A and 23B are release sheets.

The base sheet is not particularly limited, and examples thereof include a resin sheet, paper, and a metal foil. The base sheet may be a laminated sheet in which any one or more layers are laminated on at least one surface of these base sheets. If necessary, the surface of the base sheet on the side where the adhesive layer is formed may be subjected to an easy-adhesion treatment such as a corona discharge treatment and an anchor coating agent application.

The constituent resin of the resin sheet is not particularly limited, and is an ester resin such as polyethylene terephthalate (PET); an olefin resin such as polyethylene (PE) and polypropylene (PP); a vinyl resin such as polyvinyl chloride; Amid-based resins; urethane-based resins (including foams); combinations thereof and the like can be mentioned.
As described above, the first and second pressure-sensitive adhesives of the present invention have excellent substrate adhesion to both PET sheets and relatively low-polarity substrates such as PP sheets. .. Therefore, in the pressure-sensitive adhesive sheet of the present invention, the degree of freedom in selecting the base material sheet to be used is high, which is preferable. For example, by using an inexpensive PP sheet or the like, the cost of the adhesive sheet can be reduced.
The thickness of the resin sheet excluding the polyurethane sheet is not particularly limited, and is preferably 15 to 300 μm. The thickness of the polyurethane sheet (including the foam) is not particularly limited, and is preferably 20 to 50,000 μm.

The paper is not particularly limited, and examples thereof include plain paper, coated paper, and art paper.
The constituent metal of the metal foil is not particularly limited, and examples thereof include aluminum, copper, and combinations thereof.

The release sheet is not particularly limited, and a known release sheet in which a known release treatment such as coating a release agent is applied to the surface of a base sheet such as a resin sheet or paper can be used.

The adhesive sheet can be produced by a known method.
First, the surface of the base sheet is coated with the first pressure-sensitive adhesive of the present invention or the second pressure-sensitive adhesive of the present invention, and comprises the first pressure-sensitive adhesive of the present invention or the second pressure-sensitive adhesive of the present invention. Form a coating layer. A known method can be applied as the coating method, and examples thereof include 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.
Next, the coating layer is dried and cured to form an adhesive layer composed of a cured product of the first pressure-sensitive adhesive of the present invention or the second pressure-sensitive adhesive of the present invention. The heating and drying temperature is not particularly limited, and is preferably about 60 to 150 ° C. The thickness of the adhesive layer (thickness after drying) varies depending on the application, but is preferably 0.1 to 200 μm.
Next, if necessary, a release sheet is attached to the exposed surface of the adhesive layer by a known method.
As described above, the single-sided adhesive sheet can be manufactured.
By performing the above operation on both sides, a double-sided adhesive sheet can be manufactured.

Contrary to the above method, the pressure-sensitive adhesive of the present invention is applied to the surface of the release sheet to form a coating layer made of the pressure-sensitive adhesive of the present invention, and then the coating layer is dried and cured to form the present invention. A pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive may be formed, and a base material sheet may be laminated on the exposed surface of the pressure-sensitive adhesive layer.

(Use)
The adhesive sheet of the present invention can be used in the form of tapes, labels, stickers, double-sided tapes and the like. The adhesive sheet of the present invention is suitably used as a surface protective sheet, a cosmetic sheet, a non-slip sheet, and the like.
Flat panel displays such as liquid crystal displays (LCDs) and organic electroluminescence displays (OELDs), as well as touch panel displays that combine such flat panel displays and touch panels, include televisions (TVs), personal computers (PCs), mobile phones, and the like. It is widely used in electronic devices such as mobile information terminals.

The adhesive sheet of the present invention is suitably used as a surface protective sheet for flat panel displays and touch panel displays, as well as substrates and optical members manufactured or used in these manufacturing processes.
The range of use of the above electronic devices is expanding, and there is a possibility that they will be placed in a hot and humid environment that is harsher than before.
The pressure-sensitive adhesive sheet of the present invention is preferable because it has good adhesiveness and can have good removability even when placed in a higher temperature and higher humidity environment than before.

Since the pressure-sensitive adhesive sheet of the present invention has better adhesion to the base material than the conventional one, the degree of freedom in selecting the base material sheet to be used is high, and it can be suitably used for various purposes. By using an inexpensive base sheet, it is possible to reduce the cost of the adhesive sheet.

The pressure-sensitive adhesive sheet of the present invention is more excellent in curvature than the conventional one. Therefore, the adhesive sheet of the present invention can be suitably used as a flexible display such as OELD using a plastic film as a substrate, and as a surface protective sheet for a substrate and an optical member manufactured or used in this manufacturing process. it can.

As described above, according to the present invention, an adhesive capable of forming an adhesive layer having good removability even when placed in a high temperature and high humidity environment harsher than the conventional one, and an adhesive thereof. The used adhesive sheet can be provided.
According to the present invention, it is also possible to provide a pressure-sensitive adhesive having good adhesion to a base material and a pressure-sensitive adhesive sheet using the same.
According to the present invention, it is also possible to provide a pressure-sensitive adhesive having good curvature and a pressure-sensitive adhesive sheet using the same.

Hereinafter, synthesis examples, examples according to the present invention, and comparative examples will be described. In the following description, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[Measurement of Mw and Mn]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by the gel permeation chromatography (GPC) method. The measurement conditions were as follows. Both Mw and Mn are polystyrene-equivalent values.
<Measurement conditions>
Equipment: SHIMADZU Prominence (manufactured by Shimadzu Corporation),
Column: SHODEX LF-804 (manufactured by Showa Denko KK) connected in series,
Detector: Differential refractometer,
Solvent: tetrahydrofuran (THF),
Flow velocity: 0.5 mL / min,
Solvent temperature: 40 ° C,
Sample concentration: 0.1%,
Sample injection volume: 100 μL.

[material]
The materials used are as follows.
<First polyol (x)>
(X-1): P-1010 (manufactured by Kuraray Co., Ltd.), bifunctional polyester polyol, Mn1000, number of hydroxyl groups 2,
(X-2): P-2010 (manufactured by Kuraray), bifunctional polyester polyol, Mn2000, number of hydroxyl groups 2,
(X-3): PP-1000 (manufactured by Sanyo Chemical Industries, Ltd.), bifunctional polyether polyol, Mn1000, number of hydroxyl groups 2,
(X-4): PP-2000 (manufactured by Sanyo Chemical Industries, Ltd.), bifunctional polyether polyol, Mn2000, number of hydroxyl groups 2,
(X-5): TG-1000 (manufactured by NOF CORPORATION), trifunctional polyether polyol, Mn1000, number of hydroxyl groups 3,
(X-6): G-3000B (manufactured by ADEKA CORPORATION), trifunctional polyether polyol, Mn3000, number of hydroxyl groups 3,
(X-7): AM302 (manufactured by ADEKA CORPORATION), trifunctional polyether polyol, Mn3000, number of hydroxyl groups 3,
(X-8): Excelol 820 (manufactured by Asahi Glass Co., Ltd.), trifunctional polyether polyol, Mn4900, number of hydroxyl groups 3,
(X-9): F-3010 (manufactured by Kuraray Co., Ltd.), trifunctional polyester polyol, Mn3000, number of hydroxyl groups 3.

<Polyisocyanate (y)>
(Y-1): Death Module H (manufactured by Tosoh Corporation), 1,6-hexamethylene diisocyanate,
(Y-2): Takenate 500 (manufactured by Mitsui Chemicals, Inc.), 1,3-xylylene diisocyanate,
(Y-3): VESTANAT IPDI (manufactured by EVONIK), isophorone diisocyanate.

<Polyfunctional isocyanate compound (B)>
(B-1) Coronate HL (manufactured by Tosoh Corporation), hexamethylene diisocyanate / trimethylolpropane adduct,
(B-2) Sumijour N-3300 (manufactured by Sumika Bayer Urethane), hexamethylene diisocyanate / isocyanurate,
(B-3) Sumijour N-75 (manufactured by Sumika Bayer Urethane Co., Ltd.), Hexamethylene diisocyanate / Isocyanate
(B-4) Death module Z4470BA (manufactured by Sumika Bayer Urethane Co., Ltd.), isophorone diisocyanate / isocyanurate.

<Second polyol (C)>
(C-1): 1,3-butanediol (manufactured by Daicel), 1,3-butanediol, Mn90, number of hydroxyl groups 2,
(C-2): BEPG (manufactured by KH Neochem), 2-butyl-2-ethyl-1.3-propanediol, Mn160, number of hydroxyl groups 2,
(C-3): TMP (manufactured by Mitsubishi Gas Chemical Company, Inc.), trimethylolpropane, Mn134, number of hydroxyl groups 3,
(C-12): 1,4-butanediol (manufactured by Mitsubishi Chemical Corporation), 1,4-butanediol, Mn90, number of hydroxyl groups 2,
(C-13): Propylene glycol (manufactured by Dow Chemical Co., Ltd.), 1,2-propanediol, Mn76, number of hydroxyl groups 2,
(C-14): Neopentyl glycol (manufactured by Ube Industries, Ltd.), 2,2-dimethyl-1.3-propanediol, Mn104, number of hydroxyl groups 2,
(C-15): Hexanediol (manufactured by Ube Industries, Ltd.), 1,6-hexanediol, Mn118, number of hydroxyl groups 2,
(C-16): MPD (manufactured by Kuraray), 3-methyl-1,5-pentanediol, Mn118, number of hydroxyl groups 2,
(C-17): Octanediol (manufactured by KH Neochem), 2-ethyl-1,3-hexanediol, Mn146, number of hydroxyl groups 2,
(C-18): Kyowadiol PD-9 (manufactured by KH Neochem), 2.4-diethyl-1,5-pentanediol, Mn160, number of hydroxyl groups 2,
(C-20): 1,10-decanediol (manufactured by Kokura Synthetic Industry Co., Ltd.), 1,10-decanediol, Mn174, number of hydroxyl groups 2.
Table 4 shows a list of the second polyol (C) and its main properties.

<Plasticizer (P)>
(P-1): NIKKOL IPM-100 (manufactured by Nikko Chemicals Co., Ltd.), isopropyl myristate,
(P-2): Unistar M-182A (manufactured by NOF CORPORATION), methyl oleate,
(P-3): ADEKA Sizer RS735 (manufactured by ADEKA), polyether ester compound,
(P-4): TOP (manufactured by Daihachi Chemical Industry Co., Ltd.), phosphate ester,
(P-5): T-80 (manufactured by Toho Chemical Industry Co., Ltd.), polyoxyethylene sorbitan monooleate.

<Antioxidant (I)>
(I-1): IRGANOX 1135 (manufactured by BASF).

[Synthesis example of polyurethane polyol]
(Synthesis Example 1)
A four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen introduction tube, a thermometer, and a dropping funnel was charged with 100 parts of the first polyol (x) having a Mn of more than 300. To this, 70 parts of toluene was added as a solvent, 0.03 part of dibutyltin dilaurate and 0.01 part of tin 2-ethylhexanoate were added as a catalyst, and then the temperature was gradually raised to 90 ° C. under a nitrogen atmosphere. Polyisocyanate (y-3) was added dropwise thereto, and the reaction was carried out for 2 hours after the completion of the addition. After confirming the disappearance of the residual isocyanate group by infrared absorption spectrum (IR), the reaction solution was cooled to terminate the reaction. As described above, a solution of polyurethane polyol (AX-1) (nonvolatile content: 60%) was obtained. The Mw of the obtained polyurethane polyol (AX-1) was 202,000.

(Synthesis Examples 2 to 17)
In Synthesis Examples 2 to 17, polyurethane polyols (polyurethane polyols were used in the same manner as in Synthesis Example 1 except that the types of polyols and polyisocyanates used and their blending ratios were changed as shown in Tables 1-1 and 1-2. AX-2) to (AX-9) and (AY-10) to (AY-17) were obtained. In each synthesis example, the Mw of the obtained polyurethane polyol is shown in Table 1-1 and Table 1-2.

[Manufacturing of urethane adhesive]
(Example 1)
100 parts of polyurethane polyol (AX-1) obtained in Synthesis Example 1, 5 parts of polyfunctional isocyanate compound (B-1), 1 part of second polyol (C-1), antioxidant (I-1) 1 A urethane-based pressure-sensitive adhesive was obtained by blending 50 parts of ethyl acetate as a solvent and stirring with a disper. The blending amount of each material excluding the solvent indicates a non-volatile content conversion value (the same applies to other examples and comparative examples). Table 2-1 shows the types of materials used and the compounding ratios.

(Examples 2-34, Comparative Examples 1-5)
In each of Examples 2-34 and Comparative Examples 1-5, the same as in Example 1 except that the type and compounding ratio of the materials used were changed as shown in Tables 2-1 to 2-3. A urethane adhesive was obtained.

[Manufacturing and evaluation of adhesive sheets]
In each of Examples 1 to 34 and Comparative Examples 1 to 5, the pressure-sensitive adhesive sheet was produced and evaluated as follows.
(Manufacturing of adhesive sheet)
As a base sheet, a polyethylene terephthalate (PET) sheet (“Lumilar T-60” manufactured by Toray Industries, Inc., thickness 50 μm) was prepared. Using a comma coater (registered trademark), the obtained urethane-based adhesive was applied to one side of the base sheet so that the coating speed was 3 m / min and the thickness after drying was 12 μm. Next, the formed coating layer was dried at 100 ° C. for 2 minutes to form an adhesive layer. A release sheet having a thickness of 38 μm (“Super Stick SP-PET38” manufactured by Lintec Corporation) was attached onto the adhesive layer to obtain an adhesive sheet. The obtained adhesive sheet was cured under the condition of 23 ° C.-50% RH for 1 week, and then subjected to evaluation of adhesive strength, removability (adhesion contamination suppressing property), substrate adhesion, and curvature. ..

[Evaluation items and evaluation methods]
The evaluation items and evaluation methods are as follows.
(Adhesive force)
Two test pieces having a width of 25 mm and a length of 100 mm were cut out from the adhesive sheet. The release sheets were peeled off from each of the two test pieces in an atmosphere of 23 ° C. to 50% RH, a soda glass plate was attached to the surface of the exposed adhesive layer, and the two test pieces were pressure-bonded with a 2 kg roll.
One of the two obtained laminates was left to stand for 24 hours in an atmosphere of 23 ° C.-50% RH (temperature / humidity condition 1).
The other laminate was left in an oven at 85 ° C.-85% RH for 24 hours (temperature / humidity condition 2), then removed from the oven and air-cooled in an atmosphere of 23 ° C.-50% RH for 1 hour.
The adhesive strength of each laminated body was measured in accordance with JIS Z 0237 using a tensile tester under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °. The evaluation criteria are as follows.
◯: Less than 20 mN / 25 mm, good.
Δ: 20 to 100 mN / 25 mm, practically possible.
X: Over 100 mN / 25 mm, not practical.

(Removability (suppression of adherent contamination))
Three test pieces having a width of 70 mm and a length of 100 mm were cut out from the adhesive sheet. For each of the three test pieces, the release sheet was peeled off in an atmosphere of 23 ° C.-50% RH, a caustic soda glass plate was attached to the surface of the exposed adhesive layer, and the three test pieces were pressure-bonded with a laminator.
The three obtained laminates were adjusted to 40 ° C.-90% RH (temperature / humidity condition 1), 60 ° C.-90% RH (temperature / humidity condition 2), and 85 ° C.-85% RH (temperature / humidity condition 3), respectively. It was left in the set oven for 72 hours.
Each of the three laminates was taken out of the oven, air-cooled in an atmosphere of 23 ° C.-50% RH for 1 hour, and then the adhesive sheet was peeled off from the glass plate to evaluate the re-peelability. The surface of the glass plate on the side where the adhesive sheet was attached was irradiated with LED lamp light in a dark room, and evaluated by visual observation. The evaluation criteria are as follows.
⊚: Excellent, with no adhesion of adhesive layer components on the glass surface.
◯: Good, with thin adhesive layer components adhering to one or two places on the glass surface.
Δ: Thin adhesive layer components are observed at three points on the glass surface, which is practical.
X: Thin adhesive layer component is observed at 4 or more points on the glass surface / or thick adhesive layer component is observed at 1 or 2 points on the glass surface, which is not practical.

(Adhesion to base material)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet was half-cut 11 times at 1 mm intervals in two linear directions orthogonal to each other to form 100 squares of 1 mm square. After rubbing the entire 100 squares with a finger for 1 minute, the number of squares remaining on the base sheet was visually counted.
The evaluation criteria are as follows.
⊚: The number of remaining squares is 95 to 100, excellent.
◯: The number of remaining squares is 80 to 95, which is good.
Δ: The number of remaining squares is 60 to 80, which is practical.
×: The number of remaining squares is 0 to 60, which is not practical.

(Curvability)
A test piece having a width of 20 mm and a length of 15 mm was cut out from the adhesive sheet. In an atmosphere of 23 ° C.-50% RH, peel off the release sheet from the test piece, attach the surface of the exposed adhesive layer around a polypropylene (PP) round bar with a length of 30 cm and a diameter of 60 mmφ, and use your finger. Strongly crimped. At this time, the width direction of the test piece was set to be parallel to the length direction of the round bar. The sample was allowed to stand in an atmosphere of 23 ° C.-50% RH for 24 hours. Then, the length of the peeling range from the round bar was measured at both ends of the pressure-sensitive adhesive sheet, and the end having the larger peeling range was evaluated according to the following criteria.
⊚: No peeling range / or peeling range is less than 1 mm, excellent.
◯: The peeling range is 1 mm or more and less than 2 mm, which is good.
Δ: Peeling range is 2 mm or more and 5 mm, practically possible.
X: The peeling range is 5 mm or more, which is not practical.

[Evaluation results]
The evaluation results are shown in Tables 3-1 to 3-3.

In Examples 1-18,
One or more polyurethane polyols (AX) which are copolymer reaction products of one or more first polyols (x) having Mn of more than 300 and one or more organic polyisocyanates (y).
With one or more polyfunctional isocyanate compounds (B),
A urethane-based pressure-sensitive adhesive containing one or more second polyols (C) having a Mn of 300 or less was produced.

In Examples 19 to 34
Copolymerization of one or more first polyols (x) having a Mn of more than 300, one or more second polyols (C) having an Mn of 300 or less, and one or more organic polyisocyanates (y). One or more polyurethane polyols (AY), which are reaction products, and
A urethane-based pressure-sensitive adhesive containing one or more polyfunctional isocyanate compounds (B) was produced.

All of the pressure-sensitive adhesive sheets obtained in Examples 1 to 34 had good or relatively good results in all the evaluation items.

In particular, one or more second polyols (C) having Mn of 300 or less are added to one or more kinds of polyurethane polyols (AX), and the amount of one or more kinds of polyurethane polyols (AX) is 100 parts by mass by mass. In Examples 1, 3, 5 to 10, and 12 to 18, the amount of the second polyol (C) of one or more kinds was 0.1 to 10 parts by mass, and the substrate adhesion was excellent. It was.

In particular, one or more first polyols (x) having a Mn of more than 300, one or more second polyols (C) having a number average molecular weight of 300 or less, and one or more organic polyisocyanates (y). The pressure-sensitive adhesive sheets obtained in Examples 19 to 34 using one or more kinds of polyurethane polyols (AY), which are copolymerization reaction products with, had excellent curvability.

On the other hand, the second polyol (C) is not used as the raw material polyol of the polyurethane polyol (A), and the second polyol (C) is obtained with respect to the polyurethane polyol (A) and the polyfunctional isocyanate compound (B). All of the adhesive sheets obtained in Comparative Examples 1 to 5 to which was not added were subjected to temperature / humidity condition 3 (85 ° C.-85% RH) for evaluation of removability (adhesion contamination suppressing property) and adhered to the base material. The results were poor in the evaluation items of sex and curvature.

The present invention is not limited to the above-described embodiments and examples, and the design can be appropriately changed as long as the gist of the present invention is not deviated.

10, 20 Adhesive sheet 11, 21 Base sheet 12, 22A, 22B Adhesive layer 13, 23A, 23B Release sheet

Claims (6)

With one or more polyurethane polyols (AX) which are copolymer reaction products of one or more first polyols (x) having a number average molecular weight of 1000 to 4900 and one or more organic polyisocyanates (y). ,
With one or more polyfunctional isocyanate compounds (B),
The number average molecular weight comprises one or more second polyol and (C) is 76 to 174,
A pressure-sensitive adhesive in which one or more first polyols (x) contain a bifunctional polyol (x1) and / or a trifunctional polyol (x2). The pressure-sensitive adhesive according to claim 1 , further comprising one or more plasticizers (P). The pressure-sensitive adhesive according to claim 1 or 2 , wherein the second polyol (C) is water-soluble. Any of claims 1 to 3, wherein when the amount of one or more kinds of polyurethane polyols (AX) is 100 parts by mass, the amount of one or more kinds of second polyols (C) is 0.1 to 10 parts by mass. a pressure-sensitive adhesive according to any. The pressure-sensitive adhesive according to any one of claims 1 to 4 , wherein one or more first polyols (x) contain a bifunctional polyol (x1) and a trifunctional polyol (x2). A pressure-sensitive adhesive sheet comprising a base material sheet and a pressure-sensitive adhesive layer made of a cured product of the pressure-sensitive adhesive according to any one of claims 1 to 5.

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