JP6536147B2 - Urethane prepolymer, and two-component urethane adhesive using the same - Google Patents

Description

  The present invention relates to a urethane prepolymer and a two-component curable urethane adhesive using the same.

  Adhesives are used, for example, in tapes, labels, seals, cosmetic sheets, non-slip sheets, double-sided adhesive tapes, etc. In recent years, various kinds of liquid crystal displays such as personal computers, televisions, mobile phones, touch panels, etc. It is used in the field.

  As the pressure-sensitive adhesive, for example, acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, oxyalkylene-based pressure-sensitive adhesives, etc. are known. Acrylic-based pressure-sensitive adhesives tend to be used in a wide range of applications, from mold-type pressure-sensitive adhesives to slightly adhesive-type pressure-sensitive adhesives having minute adhesion.

  However, when the acrylic monomer remains in the pressure sensitive adhesive, the odor and the skin irritation become a problem. In addition, the acrylic pressure-sensitive adhesive tends to increase in adhesion or increase in transferability with time after being attached to an adherend. For this reason, there is a problem that adhesive residue is easily generated on the adherend and removability tends to be insufficient. In addition, in the case of an acrylic pressure-sensitive adhesive, since a comonomer having a high glass transition temperature is used to express cohesion, there is a problem that the impact resistance at low temperatures is insufficient and the low temperature characteristics are inferior.

  In contrast, urethane-based pressure-sensitive adhesives have the advantage of being smaller in molecular weight than acrylic pressure-sensitive adhesives and able to easily follow changes in the shape of adherends, but because it is difficult to achieve high molecular weight, curing agents Cohesive force is secured by containing. In the case of a pressure-sensitive adhesive in which the amount of the curing agent added is large, it is said that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has a high elastic modulus and is unlikely to have a high adhesion.

  For example, Patent Document 1 discloses a polyether polyol having an average functional group number of 2.2 to 3.4 per molecule, a polyisocyanate compound, and a catalyst as a pressure-sensitive adhesive having a low peeling rate dependency and good transparency. Polyurethane containing OH-terminated urethane prepolymer A containing the following and polyfunctional isocyanate compound B in the range of 0.5 to 1.6 as the equivalent ratio of the OH group of component A and the NCO group of component B as NCO / OH An adhesive composition is disclosed.

  However, the polyurethane pressure-sensitive adhesive composition described in Patent Document 1 has a low molecular weight of polyether polyol and uses a large amount of trifunctional polyether polyol, so the viscosity of the urethane prepolymer increases and the handling property is deteriorated, and curing is achieved. Even when curing was carried out too much, it was insufficient in applications requiring impact resistance. Further, in the application where the step portion is large, there is a problem that the flexibility is not sufficient and the bubble can not be generated without following the step, and there is a problem that thixotropy is exhibited and the handling property at the time of coating is poor. Furthermore, since the adhesive strength is low, the adhesion to the substrate is poor. In addition, since the molecular weight of the polyol used is relatively low and the amount of isocyanate used is relatively large, the solubility in solvents is poor, and there is a concern that appearance defects may occur due to undissolved components.

JP, 2006-182795, A

  The present invention has been made in view of the above background art, and its object is to use a urethane prepolymer having low viscosity, good handling, and appropriate curability, and a two-component curable urethane using the same. It is to provide an adhesive.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors can solve the said subject by mix | blending polyether diol of specific unsaturation degree, molecular weight, and polyisocyanate by a specific compounding ratio. The present invention has been completed.

  That is, the present invention relates to a urethane prepolymer and a two-component curable urethane adhesive using the same as described below.

[1] A urethane prepolymer obtained by using polyether diol A and polyisocyanate C, which is
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is 3,000 to 30,000, and the NCO group of the polyisocyanate C and the total amount of OH groups of the polyether diol A A urethane prepolymer having a ratio of 0.85 to 1.15 (molar ratio).

[2] The degree of unsaturation (meq / g) and the number average molecular weight of polyether diol A are represented by the following formula:
Degree of unsaturation ≦ number average molecular weight × 0.00001
The urethane prepolymer according to the above [1], characterized in that

  [3] The urethane prepolymer according to the above [1] or [2], wherein the polyisocyanate C is at least one selected from the group consisting of aliphatic isocyanates, alicyclic isocyanates and modified products thereof. .

  [4] The urethane prepolymer according to any one of the above [1] to [3], wherein the number average molecular weight (Mn) in terms of standard polystyrene is in the range of 30,000 to 300,000.

  [5] Any one of the above-mentioned [1] to [4], wherein the polyether diol A is obtained by ring-opening polymerization of an alkylene oxide using an imino group-containing phosphazenium salt catalyst Urethane prepolymer described in.

  [6] A urethane prepolymer solution having a concentration of 10 to 90% by weight of the urethane prepolymer obtained using the urethane prepolymer according to any one of the above [1] to [5] and a solvent.

  [7] A cured product obtained by using the urethane prepolymer according to any one of the above [1] to [5] and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group Two-part curing polyurethane characterized by

  [8] The two-part curable polyurethane according to the above [8], which contains the crosslinking agent D in the range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer.

  [9] A urethane adhesive containing the urethane prepolymer according to any one of the above [1] to [5].

  [10] A two-component curable urethane adhesive obtained using the two-component curable polyurethane according to the above [7] or [8].

  [11] An optical pressure-sensitive adhesive sheet obtained using the urethane adhesive according to the above [9] or [10].

  Hereinafter, the present invention will be described in detail.

  The urethane prepolymer of the present invention has a low viscosity, can be handled well, and has appropriate curability.

  In addition, since the two-component curable polyurethane of the present invention has high flexibility and low temperature characteristics and exhibits impact resistance and adhesiveness, it can be suitably used as a two-component curable urethane adhesive.

  Hereinafter, the present invention will be described in detail.

A urethane prepolymer obtained by using the polyether diol A of the present invention and a polyisocyanate C,
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is 3,000 to 30,000, and the NCO group of the polyisocyanate C and the total amount of OH groups of the polyether diol A It is characterized in that the ratio of is in the range of 0.85 to 1.15 (molar ratio).

<Polyether diol A>
The polyether diol A used for the urethane prepolymer of the present invention is preferably a compound having an oxyalkylene group and having two hydroxyl groups per molecule in an arbitrary position such as a polymer end or a branched end. .

  Examples of such polyether diol A include, but are not particularly limited to, bifunctional polyalkylene oxides such as polyoxypropylene glycol, polyoxyethylene glycol and poly (oxypropylene-oxyethylene) diol. Specifically, Sanyo Chemical Industries, Ltd. Sannix PP-1000, PP-2000, PP-3000, PP-4000, Mitsui Chemical Co., Ltd. Actol P-22, P-21, P-23, P-28 , ED-28, Asahi Glass Co., Ltd. Exenol 720, 1020, 2020, 3020, 4020, 510, 4002, 4010, 4019, 5001, 5005, Preminor 4002, 5005, Preminor S4004, 4011, 4012, 4015, 4008F, 4318F, 4318F , Oil Commercial products such as Uniol D-1000, D-1200, D-2000, D-4000, PB-700, PEG # 1500, PEG # 2000, Pronon # 102, # 104, # 202B, # 204, etc. Can.

  The polyether diol A is not limited to one type, and plural types of polyether diols may be mixed and used.

  The polyether diol A preferably has an oxypropylene group, and may have an oxyethylene group.

  The number average molecular weight (Mn) of the polyether diol A is in the range of 3000 to 30000. More preferably, it is in the range of 3500 to 20000, and most preferably in the range of 4000 to 15000. If the number average molecular weight of the polyether diol A is less than 3000, curing proceeds too early, the pot life is short and molding is difficult, and the resulting cured product also has no flexibility. Instead, it is difficult to use because it can not follow the step and generate air bubbles. In addition, when the number average molecular weight of the polyether diol A exceeds 30,000, the cohesion is insufficient and the curability is not sufficient and the use is difficult, and the urethane prepolymer is industrially synthesized due to the decrease in reactivity and the increase in viscosity. It is also difficult to do.

In the present invention, the “number average molecular weight” of the polyether diol A is based on the hydroxyl value (OHV, unit is mg KOH / g) of the polyether diol A, and the following formula:
Number-average molecular weight = (56100 / OHV) × value calculated using the number of hydroxyl groups per molecule.

  Here, “OHV” is a value measured in accordance with JIS K1557 6.4. In addition, “the number of hydroxyl groups per molecule” refers to the number of active hydrogen atoms per molecule of initiator used as a raw material when producing polyether diol A, for example, ethylene glycol and propylene glycol are 2 Yes, glycerin and trimethylolpropane are 3. When the number of active hydrogen atoms of the initiator can not be specified in commercial products, the nominal functional group number is used.

  The molecular weight distribution of the polyether diol A is not particularly limited, but preferably less than 1.16, more preferably less than 1.13, and particularly preferably less than 1.10. By setting the molecular weight distribution to less than 1.16, it is possible to expect viscosity reduction of the obtained prepolymer and improvement in reactivity of prepolymerization.

  In the present invention, the molecular weight distribution (Mw / Mn) of the polyether diol A is a polystyrene obtained by measurement by gel permeation chromatography (GPC) using a calibration curve prepared using a standard polystyrene sample of known molecular weight. It is a distribution of converted molecular weight, which is a value obtained by dividing GPC mass average molecular weight (Mw) by GPC number average molecular weight (Mn). The molecular weight distribution by the GPC method can be determined, for example, in terms of polystyrene by measuring at 40 ° C. using tetrahydrofuran as a solvent.

  The degree of unsaturation of polyether diol A is 0.07 meq / g or less. It is preferably in the range of 0.01 to 0.07 meq / g, more preferably in the range of 0.014 to 0.06 meq / g. When the degree of unsaturation of the polyether diol A exceeds 0.07 meq / g, the resulting urethane prepolymer does not exhibit good curability and is a cured product in which a large amount of migration components are generated, making it difficult to use.

  When two or more polyether diols are used in combination to form polyether diol A, the degree of unsaturation of each polyether diol is preferably 0.07 meq / g or less, but the degree of unsaturation is 0.07 meq / When a polyether diol of g or more is used, it may be mixed with other polyether diols so that the average total unsaturation degree of the mixture is 0.07 meq / g or less.

The degree of unsaturation of the polyether diol A is an indicator of the amount of monool present in the polyether diol A, and increasing may decrease the average number of functional groups f _A , but in the present invention, including them, It is referred to as "polyether diol A".

  In the present invention, “degree of unsaturation (meq / g)” of polyether diol A is the total amount of unsaturated groups contained per 1 g of polyether diol A, as defined in JIS K 1557 6.7. Measured according to the following method.

The degree of unsaturation (meq / g) and the number average molecular weight of the polyether diol A used for the urethane prepolymer of the present invention are given by the following formulas:
Degree of unsaturation ≦ number average molecular weight × 0.00001
It is preferable to satisfy Among them, the following formula:
Number average molecular weight × 0.0000025 ≦ degree of unsaturation ≦ number average molecular weight × 0.000009
It is preferable to satisfy the following formula:
Number average molecular weight × 0.000003 ≦ degree of unsaturation ≦ number average molecular weight × 0.000008
It is further preferable that By setting the degree of unsaturation of the polyether diol A to the number average molecular weight × 0.00001 or less, it is preferable since good flexibility can be expected from the obtained cured product of the urethane prepolymer.

  There is no restriction | limiting in particular as a manufacturing method of polyether diol A, It can manufacture by a conventionally well-known manufacturing method. For example, it can be produced by ring-opening polymerization of an alkylene oxide in the presence of a ring-opening polymerization catalyst using a bifunctional initiator.

  The ring-opening polymerization catalyst is not particularly limited. For example, general-purpose alkali metal compound catalysts such as potassium hydroxide (KOH) and sodium hydroxide; cesium metal compound catalysts such as cesium hydroxide; composites such as zinc hexacyanocobaltate complex Examples include metal cyanide complex catalysts; phosphazene catalysts, imino group-containing phosphazenium catalysts, barium hydroxide catalysts and the like. These catalysts may be used alone or in combination of two or more.

  Among these catalysts, in order to produce polyether diol A having a low degree of unsaturation, a cesium metal compound catalyst, a composite metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing phosphazenium salt catalyst, barium hydroxide It is preferable to use a catalyst or the like. In addition, since the molecular weight distribution of the obtained polyether diol A becomes narrow by producing the polyether diol A using an imino group-containing phosphazenium salt catalyst, the polyether diol A, and a prepolymer using the same It is preferable because a decrease in viscosity and a reduction in the amount of transition components in the cured product can be expected.

  The imino group-containing phosphazenium salt catalyst is not particularly limited as long as it is a compound having an imino group and a P-N bond, and examples thereof include compounds represented by the following general formula (for example, JP-A-2011-132179) No. 2).

[In the above general formula, R ₁ and R ₂ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ₁ and R ₂ may be bonded to each other to form a ring structure, or R _{1 's} or R _{2' s} may be bonded to each other to form a ring structure. X ^- represents a hydroxy anion, an alkoxy anion having 1 to 4 carbon atoms, a carboxy anion, an alkyl carboxy anion having 2 to 5 carbon atoms, or a hydrogen carbonate anion. ]
The bifunctional initiator is not particularly limited, and examples thereof include difunctional polyols such as water, propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, butylene glycol, 1,6-hexanediol, and polyoxyalkylene diol. Choose from compounds with two active hydrogens such as bisphenols such as bisphenol A, bisphenol F, bisphenol AD, catechols, resorcines, dihydroxybenzenes such as hydroquinone, amines such as methylamine, ethylamine, propylamine, butylamine etc. One or two or more of them are used.

  The alkylene oxide is not particularly limited. For example, one or more selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide is used.

  Among them, preferred is a polyether diol obtained by using one or two or more kinds of the above bifunctional initiators and one or two or more kinds of ring-opening polymerization of a 3-membered ring alkylene oxide having 2 to 3 carbon atoms.

  Specifically, the method for producing the polyether diol A includes one step using a cesium metal compound catalyst, a double metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing phosphazenium salt catalyst, a barium hydroxide catalyst, etc. Method of adding alkylene oxide up to a predetermined molecular weight, Bifunctional initiator, potassium hydroxide catalyst, cesium metal compound catalyst, complex metal cyanide complex catalyst, phosphazene catalyst, imino group-containing phosphazenium salt catalyst, water An alkylene oxide is added to a number average molecular weight of about 200 to 10000 using a barium oxide catalyst or the like, and then a cesium metal compound catalyst, a composite metal cyanide complex catalyst, a phosphazene catalyst, an imino group-containing catalyst in a state where the catalyst is removed or remaining Phosphazenium salt catalyst, barium hydroxide catalyst, etc. 1 Or a method in which addition of an alkylene oxide is exemplified by 2 or more used in two or more stages until a predetermined molecular weight.

<Polyisocyanate C>
As polyisocyanate C used for the urethane prepolymer of this invention, the compound which has an at least 2 isocyanate group can be used, It does not specifically limit. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4- Cyclohexane diisocyanate, norbornane diisocyanate, lysine ester triisocyanate, 1,6,11-undeca Triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate, isocyanate-containing prepolymers by reaction thereof with polyols, and these And mixtures of two or more thereof. Furthermore, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, biuret group, isocyanurate group, amido group, imide group, uretonimine group, uretdione group or oxazolidone group-containing modified product) and polymethylene Also included are condensates (sometimes referred to as polynuclears) such as polyphenylene polyisocyanates (polymeric MDI).

  Among these, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof are preferable because flexibility, impact resistance, and transparency are easily expressed. For example, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, fat Group isocyanate-containing prepolymer, alicyclic isocyanate-containing prepolymer, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, biuret group, isocyanurate group, amido group, imide group, uretonimine group, Uretdione group or oxazolidone group-containing modified products are preferred. These isocyanates may be used alone or in combination of two or more.

  Examples of isocyanate-containing prepolymers include reaction products of isocyanates with monools such as polyoxyalkylene monoalkyl ether, isotridecanol, hexyldecanol, ethyl hexanol, butyl tetraglycol, polyols, monoamines, polyamines, and the like.

  The addition amount of the polyisocyanate C used for the urethane prepolymer of the present invention is a molar ratio of the total amount of NCO groups possessed by the polyisocyanate C to the total amount of OH groups possessed by the polyether diol A ([total NCO groups] / [total amount of OH groups ) Is 0.85 to 1.15 (molar ratio), and preferably the molar ratio of the total amount of NCO groups possessed by polyisocyanate C to the total amount of OH groups possessed by polyether diol A is 0.85 to 1 .05 (molar ratio) Among these, since a prepolymer having an OH group end having high storage stability can be obtained, the ratio of the total amount of NCO groups possessed by polyisocyanate C and the OH group possessed by polyetherdiol A is 0.85 to 0.99 (moles A range of ratios) is particularly preferred. When the molar ratio of the total amount of NCO groups possessed by polyisocyanate C to the total amount of OH groups possessed by polyether diol A is less than 0.85 or in a range exceeding 1.15, curing proceeds too early and pot life Is difficult to mold, and since the resulting cured product also has no flexibility, in applications where the step portion is large, the flexibility is not sufficient and the step can not be followed to generate air bubbles, making it difficult to use.

<Active hydrogen compound B>
In addition to the polyether diol A, other active hydrogen compounds B (hereinafter referred to as "active hydrogen compounds B") can be used in combination without departing from the spirit of the present invention. The active hydrogen compound B is not particularly limited, but is, for example, a compound having at least one active hydrogen group per molecule, such as water, polyvalent carboxylic acid, polyamine, polyol and the like. When the active hydrogen compound B is used, the addition amount thereof is not particularly limited, but if too large, the impact resistance and flexibility of a cured product of the obtained urethane prepolymer may be lowered, so It is preferable to use in the range of 100 parts by weight or less with respect to 100 parts by weight of the ether diol A, and more preferably 30 parts by weight or less. Most preferably, the amount of the active hydrogen compound B is 10 parts by weight or less based on 100 parts by weight of the polyether diol A. In this case, less than 0.1 part by weight of trifunctional or higher polyether polyol in the active hydrogen compound B Is preferred. Moreover, it is preferable that the degree of unsaturation is 0.07 meq / g or less, and the number average molecular weight does not contain the trifunctional or higher polyether polyol having a range of 5,000 to 40,000.

  When using the active hydrogen compound B in addition to the polyether diol A, the addition amount of the polyisocyanate C includes the total amount of NCO groups of the polyisocyanate C and the total amount of OH groups of the polyether diol A and the active hydrogen compound B. The molar ratio is preferably 0.85 to 1.15 (molar ratio).

<Method of synthesizing urethane prepolymer>
The synthesis method of the urethane prepolymer of the present invention is not particularly limited. For example, polyether diol A, and, if necessary, active hydrogen compound B and polyisocyanate C, a urethanization catalyst, a solvent, an antifoaming material, The method of making it urethane-react in the presence of other additives etc. is mentioned. Therefore, the obtained urethane prepolymer may contain a urethanization catalyst, an antifoaming agent, an additive and the like.

  Here, the temperature of the urethanation reaction is not particularly limited, but is preferably 120 ° C. or less, more preferably 50 to 110 ° C. If it is 120 ° C. or less, it is preferable because control of reaction rate and urethane prepolymer having a predetermined number average molecular weight and structure are easily obtained.

  Therefore, the urethanation reaction is preferably carried out at 120 ° C. or less for 1 to 20 hours. The end point of the reaction can be judged by measuring the amount of residual isocyanate by titration, or the disappearance of the isocyanate peak by IR measurement.

  The urethanation reaction is not particularly limited, but a solvent may be used to facilitate reaction control. Examples of the solvent include methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, benzene, dioxane, acetonitrile, tetrahydrofuran, diglyme, dimethyl sulfoxide, N-methyl pyrrolidone, dimethyl formamide and the like. From the viewpoint of the solubility of the urethane prepolymer, the boiling point of the solvent, and the like, ethyl acetate, toluene, methyl ethyl ketone or a mixed solvent thereof is particularly preferable. These solvents may be added at any time such as at the beginning of the reaction, in the middle of the reaction, after the reaction is completed.

  The concentration of the urethane prepolymer (including the unreacted starting material excluding the solvent) in the case of using a solvent at the time of the urethanization reaction is not particularly limited and is selected depending on the application, but preferably in the range of 10 to 90% by weight It is more preferably in the range of 30 to 70% by weight. If the concentration of the urethane prepolymer in the urethane prepolymer solution is in the range of 10 to 90% by weight, the decrease in the reactivity of the urethanization is small, and the effect of improving the handling property can be expected, which is preferable.

  A known urethanization catalyst can be used in the synthesis of the urethane prepolymer of the present invention. For example, tertiary amine compounds, organic metal compounds and the like can be mentioned.

  The tertiary amine compounds include, but are not limited to, triethylamine, triethylenediamine, N, N-dimethylbenzylamine, N-methylmorpholine, diazabicycloundecene (alias: DBU), etc., alone or in combination. Two or more can be used in combination.

  Although it does not specifically limit as an organometallic compound, A tin compound and a non-tin compound can be mentioned.

  The tin-based compound is not particularly limited. For example, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (alias: DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin Sulfide, tributyl tin oxide, tributyl tin acetate, triethyl tin ethoxide, tributyl tin ethoxide, dioctyl tin oxide, tributyl tin chloride, tributyl tin trichloroacetate, dioctyl tin dilaurate (alias: DOTDL), tin 2-ethylhexanoate, etc. .

  Non-tin compounds are not particularly limited, and examples thereof include titanium such as dibutyl titanium dichloride, tetrabutyl titanate, butoxy titanium trichloride, lead oleate, lead 2-ethylhexanoate, lead benzoate, lead naphthenate, etc. Lead-based, iron-based such as iron 2-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 thereof include zirconium naphthenate and the like.

  Among the above-mentioned urethanization catalysts, dibutyltin dilaurate (alias: DBTDL), dioctyltin dilaurate (alias: DOTDL), tin 2-ethylhexanoate and the like are preferable in terms of reactivity and hygiene.

  The catalysts such as the above-mentioned tertiary amine compounds and organic metal compounds can be used alone or in combination.

  The amount of the urethanization catalyst added during synthesis of the urethane prepolymer of the present invention is not particularly limited, but if it is too small, productivity may decrease, and if too large, the reaction becomes uneven and the physical properties become unstable. In the above tertiary amine compound, 0.01 to 15 parts by weight, as described above, with respect to the total 100 parts by weight of the polyether diol A and the active hydrogen compound B optionally added The range of 0.0001 to 5 parts by weight is preferable for the organic metal compound. After synthesis, these catalysts may be removed or may remain.

  The urethane prepolymer of the present invention can be chain-extended using a chain extender in order to promote high molecular weight formation. Although not particularly limited, for example, glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethyl pentanediol, glycerin, trimethylolpropane, pentaerythritol and the like, ethylenediamine, N-aminoethylethanolamine, piperazine, The chain can be extended using polyhydric amines such as isophorone diamine and xylylene diamine.

  The urethane prepolymer of the present invention is low in viscosity and excellent in handleability because a large amount of polyether diol is used, and when it is crosslinked, a two-component polyurethane cured product having good impact resistance, flexibility and low temperature properties can be obtained. Moreover, since the polyether diol A having a low degree of unsaturation is used, the curability is excellent.

<Properties of Urethane Prepolymer>
It is desirable that the urethane prepolymer of the present invention is in the form of liquid. In the case of gel or solid, coating may be difficult, and when it is dissolved in a solvent, insolubles may occur.

  The urethane prepolymer of the present invention preferably has a reactive group in the molecule. The reactive group is not particularly limited, but preferably contains a reactive group that reacts with an isocyanate group such as an active hydrogen group, and a reactive group that reacts with an active hydrogen group such as an isocyanate group, and particularly contains a hydroxyl group at the molecular terminal It is preferable that it is a hydroxyl-terminated urethane prepolymer. When the ratio of the NCO group of the polyisocyanate C to the total OH group of the polyether diol A is 1.00 or less, the hydroxyl group has a terminal structure. In the range of more than 1.00, many of the isocyanate groups have a terminal structure.

  The terminal structure of the urethane prepolymer of the present invention is not particularly limited, and examples thereof include one or more of a hydroxyl group, an amino group, an isocyanate group, an allyl group and the like.

  The standard polystyrene equivalent number average molecular weight of the urethane prepolymer of the present invention is preferably in the range of 30,000 to 300,000, and more preferably in the range of 35,000 to 80,000. If the number average molecular weight of the urethane prepolymer is in the range of 30,000 to 300,000, the viscosity of the urethane prepolymer does not become too high, and a cured urethane product obtained is preferable because good flexibility can be expected. The number average molecular weight in terms of standard polystyrene is measured by GPC (Gel Permeation Chromatography) under conditions of column temperature 40 ° C., flow rate 1.0 ml / min, solvent THF, and a cubic polystyrene curve calibration curve using standard polystyrene It can be calculated as

  The viscosity of the urethane prepolymer of the present invention is not particularly limited and is selected according to the application, but is preferably in the range of 15 to 1,000,000 Pa · s (25 ° C.), more preferably 100 to 30,000 Pa · s (25 ° C.) And most preferably in the range of 100 to 5000 Pa · s. If the viscosity of the urethane prepolymer is in the range of 15 to 100000 Pa · s (25 ° C.), a resin having a sufficient molecular weight is formed, and dispersibility in a solvent and coating properties can be expected, which is preferable.

  The urethane prepolymer of the present invention can be used as it is as a urethane adhesive, and is suitably used as a component of a two-component curable urethane adhesive described later.

<Urethane prepolymer solution>
The urethane prepolymer solution of the present invention is obtained by using the urethane prepolymer of the present invention and a solvent, and the concentration of the urethane prepolymer is a solution in the range of 10 to 90% by weight, further in the range of 30 to 70% by weight. preferable. If the concentration of the urethane prepolymer in the urethane prepolymer solution is in the range of 10 to 90% by weight, the decrease in reactivity is small and the effect of improving the handling property can be expected, which is preferable.

  The solvent used for the urethane prepolymer solution of the present invention is not particularly limited, and, for example, methyl ethyl ketone, ethyl acetate, toluene, xylene, acetone, benzene, dioxane, acetonitrile, tetrahydrofuran, diglyme, dimethyl sulfoxide, N-methylpyrrolidone, Dimethyl formamide etc. are mentioned. Among these, ethyl acetate, toluene, methyl ethyl ketone or a mixed solvent thereof is particularly preferable in view of the solubility of the urethane prepolymer, the boiling point of the solvent and the like.

  The viscosity of the urethane prepolymer solution of the present invention is not particularly limited and is selected depending on the application, but a range of 0.1 to 100 Pa · s (25 ° C.) is preferable, and more preferably a range of Pa · s (25 ° C.) It is. If the viscosity of the urethane prepolymer solution is in the range of 0.1 to 100 Pa · s (25 ° C.), it is preferable because it exhibits adequate liquid fluidity and good handling can be expected.

  The urethane prepolymer solution of the present invention can be used as a urethane adhesive by drying, and is suitably used as a component of the two-component curable urethane adhesive described later.

Two-component curable polyurethane
The two-component curable polyurethane of the present invention is a cured product obtained using the urethane prepolymer of the present invention and a crosslinking agent D having reactivity with active hydrogen groups or isocyanate groups.

  The two-component curable polyurethane of the present invention can be provided in any shape such as a film, sheet, plate or block.

  As a method for producing the two-component curable polyurethane of the present invention, for example, the urethane prepolymer of the present invention and a crosslinking agent D having reactivity to an active hydrogen group or an isocyanate group are mixed and cured in a predetermined shape. It can be manufactured by degassing and drying as required, and manufactured in a predetermined shape. For example, it can be formed into a sheet or film by coating, and can be formed into a plate or block by molding in a mold.

  The application of the two-component curing polyurethane of the present invention is not particularly limited, but it is excellent in transparency, flexibility, and low temperature characteristics, and thus, for example, adhesives such as pressure sensitive adhesives and building elastic adhesives, surface protective films, paints, It can be used for the production of elastomers, coating waterproofing materials, floorings, sealing materials for construction and civil engineering, plasticizers, flexible polyurethane foams, semi-rigid polyurethane foams, rigid polyurethane foams and the like. Among these, a cured product having high flexibility and low temperature characteristics, and excellent impact resistance and adhesiveness can be obtained, and therefore, it can be suitably used as a two-component curable urethane adhesive.

<Crosslinking agent D>
It will not specifically limit, if it is a compound which has reactivity with respect to an active hydrogen group or a compound which has reactivity with respect to an isocyanate group as crosslinking agent D used for 2 liquid curing type polyurethane of this invention. For example, an isocyanate crosslinking agent, an aziridine crosslinking agent, an epoxy crosslinking agent, a melamine resin, a urea resin, a metal chelate crosslinking agent, a polyol crosslinking agent, an amine crosslinking agent, water, etc. may be mentioned. Since these crosslinking agents are generally liquid, they can be used as they are, but they may be used by diluting with an organic solvent, if necessary.

  If the molar ratio ([NCO group total amount] / [OH group total amount]) of the total amount of NCO groups derived from polyisocyanate C and the total amount of OH groups derived from polyether diol A in the urethane prepolymer is within the range of 1.00 or less The crosslinking agent D is preferably a compound having reactivity with an active hydrogen group. As such a crosslinking agent, an isocyanate type crosslinking agent, an aziridine type crosslinking agent, an epoxy crosslinking agent, a melamine resin, a urea resin, a metal chelate type crosslinking agent etc. are mentioned, for example. Among these, an isocyanate crosslinking agent and an epoxy crosslinking agent are preferable because they easily exhibit performance such as heat resistance.

  On the other hand, when the molar ratio of the total amount of NCO groups derived from polyisocyanate C and the total amount of OH groups derived from polyether diol A in the urethane prepolymer exceeds 1.00, the crosslinking agent D It is preferable that it is a compound having reactivity. As such a crosslinking agent, a polyol crosslinking agent, an amine crosslinking agent, water etc. are mentioned, for example.

  When the urethane prepolymer is obtained by using the active hydrogen compound B in addition to the polyether diol A, the total amount of NCO groups derived from the polyisocyanate C and the polyether diol A and the active hydrogen compound B are derived The crosslinker described above may be selected using the molar ratio to the total amount of OH groups to be used.

  As an isocyanate type crosslinking agent, the compound which has an at least 2 isocyanate group can be used, It does not specifically limit. For example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1, 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,4- Cyclohexane diisocyanate, norbornane diisocyanate, lysine ester triisocyanate, 1,6,11-un Cantriisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate, isocyanate-containing urethane prepolymers by reaction of these with polyols, A mixture of two or more of these, and the like can be mentioned. Furthermore, modified products of these isocyanates (urethane group, carbodiimide group, allophanate group, urea group, biuret group, isocyanurate group, amido group, imide group, uretonimine group, uretdione group or oxazolidone group-containing modified product) and polymethylene Also included are condensates (sometimes referred to as polynuclears) such as polyphenylene polyisocyanates (polymeric MDI).

  Among these, aliphatic isocyanates, alicyclic isocyanates, and modified products thereof are preferable because flexibility, impact resistance, and transparency of cured products of the obtained urethane prepolymers are easily developed, for example, 1, 1 6-hexamethylene diisocyanate, isophorone diisocyanate, aliphatic polyisocyanate-containing urethane prepolymer, alicyclic polyisocyanate-containing urethane prepolymer, modified products of these polyisocyanates (urethane group, carbodiimide group, allophanate group, urea group, biuret Groups, isocyanurate groups, amido groups, imide groups, uretone imine groups, uretdione groups or oxazolidone group-containing modified products) are preferred. These isocyanates may be used alone or in combination of two or more. More preferably, polyisocyanate having an allophanate group, alicyclic isocyanate having an allophanate group, and a mixture containing one or more of these allophanate-modified isocyanates, are not particularly limited, and include, for example, Coronate 2770, Coronate 2785, Coronate manufactured by Tosoh Corporation. 2792, a mixture containing one or more of these, and the like can be mentioned.

  The epoxy crosslinking agent is not particularly limited, and examples thereof include an amine type epoxy crosslinking agent having an epoxy group and an amino group, a non-amine type epoxy crosslinking agent, and examples thereof include bisphenol A, epoxy resins of epichlorohydrin type, ethylene glycidyl ether, Polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ', N'- Tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N′-diamineglycidylaminomethyl) cyclohexane, 2,2 ′-[[2,21-bis (oxirane-2-ylylmethoxy)] Chill) Single 1,3 one propanediyl] bis (oxymethylene)] bis oxirane and the like of these two or more mixtures thereof. Although not particularly limited, for example, commercially available products such as Tetrad C and Tetrad X manufactured by Mitsubishi Gas Chemical Co., Ltd., Denacol EX-411 manufactured by Nagase ChemteX Co., Ltd., Denacol EX 212, Denacol EX 214, E-5 C manufactured by Soken Chemical Co., Ltd. and the like can be mentioned.

  The polyol crosslinking agent is not particularly limited as long as it has two or more active hydrogen groups, and is not particularly limited. Ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,5-pentamethylene glycol, 1,6- Hexamethylene glycol, trimethylolpropane, low molecular weight alkylene polyol of short chain length, polyoxypropylene polyol, polyoxyethylene propylene polyol polyethylene glycol, polyester polyol, and a mixture of two or more of these, etc. may be mentioned. Among these, since a cured product having excellent curability and excellent transparency can be obtained, it is preferable that the polyol does not contain an aromatic ring and is a polyol crosslinking agent having a number average molecular weight of less than 8,000.

  The amine-based crosslinking agent is not particularly limited, but ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, triaminopropane, 2,2,4-trimethylhexamethylenediamine , 2-hydroxyethylethylenediamine, N- (2-hydroxyethyl) propylenediamine, (2-hydroxyethylpropylene) diamine, (di-2-hydroxyethylethylene) diamine, (di-2-hydroxyethylpropylene) diamine, 2-hydroxypropylethylene) diamine, (di-2-hydroxypropylethylene) diamine, aliphatic polyamine such as piperazine, isophorone diamine, dicyclohexylmethane-4, 4 Alicyclic polyamines such as diamine, phenylenediamine, xylylenediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, diethyltoluenediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane And aromatic diamines such as 4,4′-bis- (seC-butyl) diphenylmethane; polyoxyalkylene polyamines such as JeffAmine D-2000; and mixtures of two or more of these.

  Although it does not specifically limit as functional group number of the crosslinking agent D, For example, the range of 2-6 is preferable, More preferably, it is the range of 2-3. If the number of functional groups of the crosslinking agent D is in the range of 2 to 6, crosslinking is likely to proceed uniformly, and curing is also unlikely to be insufficient, which is preferable.

  The addition amount of the crosslinking agent D used for the two-component curable polyurethane of the present invention is preferably in the range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer, and further in the range of 2 to 15 equivalents. Preferably, a range of 3 to 10 equivalents is particularly preferred. If the addition amount of the crosslinking agent D is in the range of 2 to 20 equivalents (molar ratio) with respect to the reactive group (including the water content in the system) of the urethane prepolymer, it has good curability and is high It is preferable because flexibility can be expected.

<Urethane adhesive>
The urethane adhesive of the present invention is not particularly limited as long as it uses the urethane prepolymer of the present invention, and specifically, the urethane prepolymer of the present invention, or the present invention, such as the two-component curable polyurethane of the present invention The urethane adhesive obtained using the urethane prepolymer solution of invention is illustrated.

  The urethane pressure-sensitive adhesive of the present invention can be provided, for example, in any form such as a pressure-sensitive adhesive film or a pressure-sensitive adhesive sheet laminated on one or more kinds of substrates, or a liquid.

  As a base material used for the adhesive sheet using the urethane adhesive of this invention, a release film, a core material, etc. are mentioned. Examples of such a release film include PET, PP, TPX, silicones of these, release-treated films such as fluorine, etc., and commercially available products include PUREX A31, A33, A35, A43, etc. manufactured by Teijin DuPont. And release PET. As the core material, non-woven fabric, PET film, PP film and the like can be mentioned.

  As a lamination structure of a pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention, for example, a substrate-less type pressure-sensitive adhesive sheet having a three-layer structure in which both sides are sandwiched by release PET, and a five-layer structure using a core material in the pressure-sensitive adhesive layer And a double-sided pressure-sensitive adhesive sheet.

  The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention is not particularly limited, but is preferably in the range of 10 μm to 1000 μm, more preferably 15 μm to 250 μm, and most preferably It is 20 micrometers-130 micrometers. The range of 20 micrometers-150 micrometers is preferable especially in the case of the adhesive sheet for optics for film sensors, and the range of 50 micrometers-250 micrometers is preferable in the case of the adhesive sheet for optics for glass sensors between a touch panel and a cover panel.

  As a shape of the adhesive sheet using the urethane adhesive of this invention, it may be set as a desired shape. Although not particularly limited, it may be in the form of a roll, or may be cut and provided in the form of a sheet.

  The method for producing a pressure-sensitive adhesive sheet using the urethane pressure-sensitive adhesive of the present invention is not particularly limited. For example, a component containing the urethane prepolymer of the present invention and a component containing the crosslinking agent D are mixed in a predetermined ratio For example, a method of coating with a roll coater, a gravure coater, a microgravure coater, a reverse coater, an air knife coater, a comma coater, a die coater or the like after being made into a two-component curable polyurethane composition can be mentioned. When using these coating methods, it is desirable to degas, heat, and dry the two-component curable polyurethane composition on one side or both sides of the substrate, if necessary. As a method of heating, generally used methods such as hot air drying, heat roll drying, infrared irradiation and the like can be used. The drying temperature is not particularly limited, but is preferably in the range of 50 to 200 ° C, more preferably 70 to 180 ° C, and still more preferably 80 to 150 ° C. When a thermoplastic resin is used as the substrate, the drying temperature is desirably equal to or lower than its melting point. It is preferable that the drying temperature is in the range of 50 to 200 ° C. because deterioration of the substrate and change in color tone are unlikely to occur.

  It does not specifically limit as a use of the urethane adhesive of this invention, an adhesive sheet, For example, a tape, a label, a seal, a cosmetic sheet, a non-slip sheet, a double-sided adhesive tape etc. are mentioned, Specifically, A packaging tape Packaging tape, masking tape, packaging tape such as kraft tape, adhesive tape for office work and household use, medical tape such as adhesive plaster, tape for wallpaper, foam tape, architectural tape such as elastic adhesive for construction, personal computer, TV, Adhesive tape for optical materials used for adhesion of a cell phone, a car, a solar cell, other electric appliances used for other household appliances etc., liquid crystal display, a touch panel, surface protection tape or waterproof tape in the manufacturing process, conductive tape, heat dissipation tape etc. Is illustrated.

  The urethane pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention are particularly suitable for applications requiring impact resistance, for example, adhesion of fragile substrates such as glass and prevention of scattering, adhesion of electronic devices, etc. Specifically, it can be used in optical applications such as touch panel applications and electric and electronic component applications. Although it does not specifically limit as a specific use, The adhesive sheet for optics used for electronic devices, such as a smart phone, a tablet PC, a notebook computer, The protective tape of an electronic component is illustrated. Among these, it can be suitably used for adhesion of various films inside the electronic device.

<Optical adhesive sheet>
The optical pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet obtained using the urethane pressure-sensitive adhesive of the present invention and used for optical applications.

  Specific optical applications are not particularly limited, but, for example, mobile phones, smart phones, car navigation, personal computers, touch panels and displays such as ticket vending machines, and peripheral functions such as ITO films and silver meshes, copper meshes, and polarizing plates Pressure-sensitive adhesive sheet used for adhesion of an adhesive film, etc. The operation method of the touch panel is not particularly limited, and can be suitably used for a resistance film type, a capacitance type, an optical type, an ultrasonic type, an electromagnetic induction type, and the like.

  Hereinafter, the present invention will be more specifically described using examples, but the present invention is not construed as being limited by the following examples as long as the gist of the present invention is not exceeded. The materials used in the following examples and comparative examples and the evaluation methods are as follows.

  As the raw materials described in Table 2 and Table 3, the following were used respectively.

<Raw materials>
1) Polyether diol A, active hydrogen compound B

<Polyether diol A>
Polyols A1, A3 and A7: polyether diol in which propylene oxide is added to polyoxypropylene glycol having a bifunctional molecular weight of 400 using an imino group-containing phosphazenium salt (IPZ) catalyst.
Polyol A2, A4: After adding propylene oxide to polyoxypropylene glycol having a bifunctional molecular weight of 400 using a composite metal cyanide complex (DMC) catalyst manufactured by China, an imino group-containing phosphazenium salt (IPZ) catalyst Propylene oxide-added polyether diol polyol A5, A6: commercially available general-purpose polyoxypropylene glycol.
<Active hydrogen compound B>
Polyol B1: Commercially available general purpose polyoxypropylene triol.
Polyol B2: diethylene adipate polyester polyol (Nipporan 1004 manufactured by Tosoh Corporation).
These polyols A1 to B2 were used after heating and vacuum dehydration before use.

2) Polyisocyanate C
Isocyanate C 1: 1,6-hexamethylene diisocyanate (HDI).

3) Crosslinking agent D
Crosslinking agent D1: A 50% by weight mixture of 50% by weight of an allophanate-modified bifunctional HDI-based crosslinking agent (Colonate 2770 manufactured by Tosoh Corp.) and an approximately trifunctional nurate-modified HDI-based crosslinking agent (Colonate HX manufactured by Tosoh Corp.).

(Analysis of polyol properties)
<Hydroxyl value, number average molecular weight>
The hydroxyl value was measured according to the method of JIS-K1557-1. The number average molecular weight of the polyol was the hydroxyl group equivalent molecular weight calculated by the product of the number of functional groups of the initiator used for the production (commercially available is the nominal number of functional groups) and the molecular weight per hydroxyl group of the polyol.

<Degree of unsaturation>
It measured according to the method of JIS-K1557-6.

<Molecular weight distribution (Mw / Mn)>
10 mg of polyol and 10 ml of THF were added to a sample bottle, and allowed to stand for one night to dissolve, and a sample was obtained by filtering through a PTFE cartridge filter (0.5 μm). An RI detector RI 8020 was used as a detector, TSK gel GMR-H _HR L × 2 in series as a measurement column, and HLC-8020 GPC were used (all are manufactured by Tosoh Corporation). As measurement conditions, the column temperature is 40 ° C., the flow rate is 1.0 ml / min, and the solvent is used as the solvent THF, and a cubic approximation curve using standard polystyrene made by Tosoh Corporation is used as a calibration curve to obtain molecular weight distribution (Mw / Mn). The analysis was done.

(Urethane prepolymer synthesis example 1)
A predetermined amount of polyol A1 and polyisocyanate C1 was added to a four-neck separable flask equipped with a stirrer, a reflux condenser, a nitrogen introducing pipe, and a thermometer, and the temperature was raised to 70 ° C. to perform a reaction. The NCO groups of the reactor contents were followed by dibutylamine back titration and using an infra-red spectrophotometer to confirm reaction completion to obtain the urethane prepolymer of Example 1.

  The urethane prepolymers of Examples and Comparative Examples other than the urethane prepolymer synthesis example 1 are also synthesized by the same method, and appropriately added using a microsyringe within a range not exceeding 0.02% by weight of DBTDL as a catalyst according to the reaction rate etc. Depending on the stirring conditions, etc., methyl ethyl ketone was suitably added as a solvent in a range not exceeding 80% by weight.

(Urethane prepolymer solution production example 1)
Super dehydrated methyl ethyl ketone was added as a solvent to the urethane prepolymer obtained in Synthesis Example 1 and dissolved while stirring with stirring to dissolve, thereby preparing a solution having a urethane prepolymer concentration of 50%. The water content of the urethane prepolymer solution was measured by a Karl Fischer moisture meter.

  The urethane prepolymer solution other than the urethane prepolymer solution production example 1 and the solvent of the urethane prepolymer solution are added by the same method if necessary, and the urethane prepolymer concentration is 30% by weight to 100% by weight in consideration of the coating property Prepared in the range of solvents.

(Two-component cured product production example 1)
7 equivalents of a crosslinking agent D1 (Coronate 2770 manufactured by Tosoh Corp. and Coronate HX, based on the amount of active hydrogen groups including about 10 g of the solution obtained in Preparation Example 1 of urethane prepolymer solution, urethane prepolymer and water in the solution The equivalent mixture) was added to the sample bottle and stirred with a pencil mixer until uniform. The urethane prepolymer composition was allowed to stand at 50 ° C. for 30 minutes while being warmed to remove air bubbles in the system and cooled to room temperature. The release film was coated on a release PET (Purex manufactured by Teijin Ltd.) with an applicator to a dry thickness of 40 μm, and left for 30 minutes in an explosion-proof dryer heated to 80 ° C. to remove the solvent. At this point, the remaining amount of NCO groups was about 20% immediately after mixing. After completion of drying, release PET (Purex manufactured by Teijin DuPont Co., Ltd.) having a difference in release force from the base material side was pasted back and forth three times with a roller so as to prevent air bubbles from entering the surface of the cured product. Then, it is left to stand in a constant temperature room at 23 to 25 ° C. and 50% RH, and after 3 days, disappearance of NCO group is confirmed by IR. A sheet of a three-layered structure of release PET / cured product / release PET having a cured product thickness of 40 μm was prepared and used as a cured product evaluation sample (pressure-sensitive adhesive sheet) of Example 1.

  The conditions are the same using 7 equivalents of the crosslinking agent D1 (equivalent mixture of Coronate 2770 and Coronate HX manufactured by Tosoh Corp.) with respect to the total amount of active hydrogen groups including the urethane prepolymer and the water content of the solution. The hardened | cured material sheet was produced by this, and it was set as the hardened | cured material evaluation sample of Examples 2-10, respectively.

(Example of urethane prepolymer property evaluation)
<GPC number average molecular weight (Mn)>
10 mg of urethane prepolymer and 10 ml of THF were added to a sample bottle and dissolved by being allowed to stand for one night to dissolve, and a sample was obtained by filtering with a PTFE cartridge filter (0.5 μm). An RI detector RI8020 was used as a detector, TSKgelGMR-HHRL × two in series as a measurement column, and HLC-8020GPC were used (all are manufactured by Tosoh Corporation). The measurement was performed under the conditions of a column temperature of 40 ° C., a flow rate of 1.0 ml / min, and a solvent of THF, and analysis of number average molecular weight was performed as a cubic approximate curve calibration curve using standard polystyrene manufactured by Tosoh Corporation.

<Urethane prepolymer appearance>
The appearance of the urethane prepolymer was visually evaluated, and the evaluation was continued with a poor appearance in which gelation or bumps were generated as x, and a good appearance as o.

<Viscosity>
The viscosity of the urethane prepolymer alone was measured under conditions of 25 ° C. using MCR-300 manufactured by Anton-Paar, and if it was 15000 Pa or less, it would be ○ (pass), and a case exceeding 15000 Pa was regarded as x. The angular velocity dependency was evaluated in the range of 0.001 to 100 (1 / second), and the average value of the range in which it became constant was taken as the viscosity.

<Handling property>
Those that are difficult to coat when adjusted to a solution concentration of 70% and those with poor dispersibility of urethane prepolymer in solvent are ×, those that can be coated, but they move to the substrate with time and the handling is bad 、, an undiluted solution or solution which can be coated was evaluated as ○.

<Curable>
A urethane prepolymer and an isocyanate crosslinking agent D1 (equivalent mixture of Coronate 2770 and Coronate HX manufactured by Tosoh Corporation) are stirred and mixed at a molar ratio of 7 equivalents with respect to reactive groups (including water in the system) of the urethane prepolymer. When it was dried and cured, it was touched with a finger to evaluate the curability. Insufficient curing and liquid form ×, insufficient curing and migration component sticking to the finger, which may contaminate the surrounding area △, migration component with less tackiness ○, conversely curing It progressed too early, the pot life was short, and those difficult to form were also rated as xx.

(Example of evaluation of cured product characteristics)
<Impact resistance>
According to the two-component cured product production example, the obtained cured product is peeled off from the release PET, and the pressure-sensitive adhesive layer is made 200 μm by 5 sheets, laminated to a 5 cm square glass substrate of 0.7 mm thickness, and the other surface is also thick It was set as a measurement sample by laminating on a 0.7 mm glass substrate.

  A steel ball having a diameter of 5/8 inch was dropped from the height of 50 cm to the center of the measurement sample, and it was evaluated as ○ if there was no cracking or floating / peeling even if repeated three times.

<Flexibility>
According to the two-component cured product production example, the obtained cured product was peeled off from the release PET and folded back to be a measurement sample. Measured at a temperature of −80 ° C. to 200 ° C., a temperature rising rate of 2 ° C./min, a frequency of 1 Hz, shear mode conditions using Rheogel E-4000 manufactured by UBM, a dynamic viscoelasticity measuring apparatus, at 25 ° C. The storage modulus G 'was evaluated. When G ′ at 25 ° C. is 3.5 × 10 ⁵ Pa or less, flexibility ○, and when G ′ exceeds 3.5 × 10 ⁵ Pa, flexibility is considered as ×.

<Low temperature characteristics>
According to the two-component cured product production example, the obtained cured product was peeled off from the release PET and folded back to be a measurement sample. Measurement is performed under the measurement temperature of -80 ° C to 200 ° C, temperature rising rate of 2 ° C / min, frequency of 1 Hz, shear mode condition using Rheogel E-4000 manufactured by UBM company, and the storage elastic modulus G is measured. The temperature at which the peak value of tan δ, which is the ratio of loss elastic modulus G ′ ′ to ', is evaluated as the glass transition temperature. If the glass transition temperature is −40 ° C. or lower, the low temperature characteristics ○, the glass transition temperature exceeds −40 ° C. In this case, the low temperature characteristics were ×.

<Adhesive property>
According to the two-component cured product production example, the release PET of the obtained pressure-sensitive adhesive sheet was peeled on one side, and a 25 μm-thick PET film Lumirror S-10 manufactured by Toray Industries was backed on the pressure-sensitive adhesive surface. The test piece was cut into a width of 25 mm, and roll pressure-bonded to Eagle XG manufactured by non-alkali glass plate Corning in accordance with JIS Z0237 to prepare a test piece. A 180 ° peel test was performed according to JIS Z 0237 using a tensile testing machine Tentilon RTG-1210 manufactured by Orientec Co., Ltd. to measure 180 ° peel adhesion (N / 25 mm). The measurement was performed under conditions of a peeling angle of 180 ° and a tensile speed of 300 mm / min in an atmosphere of 23 ° C. and 50% RH. The number of tests was 2 or more, and the average value was calculated. 3N / 25 mm or more was ○, and 3N / 25 mm was x.

  The results of Examples 1 to 9 are shown in Table 2, and the results of Comparative Examples 1 to 6 are shown in Table 3.

Examples 1-9.
According to the composition shown in Table 2, a urethane prepolymer and a two-component cured product were synthesized and the properties were evaluated.

  In all cases, the viscosity was low and the handling properties were good, and the curability was good. It was also found that the cured product obtained using the synthesized urethane prepolymer had good impact resistance, and a cured product compatible with the flexibility and low temperature characteristics was obtained. Furthermore, in evaluation as an adhesive, it turned out that adhesiveness is high and the adhesiveness to a base material can be anticipated.

Comparative Example 1
According to the composition shown in Table 3, a urethane prepolymer was synthesized using a polyether diol having a high degree of unsaturation, and the properties were evaluated. Although there was a migration component from the cured product, the viscosity was low and the handling property was acceptable, but no curability was observed and it was difficult to use as a urethane prepolymer.

Comparative Example 2
A urethane prepolymer was synthesized by changing the polyol A5 of Comparative Example 1 to a low molecular weight polyol A6, and the properties were evaluated. Although the viscosity is low, the dispersibility in a solvent is poor and the handling property is poor, the pot life at the time of curing is short, the curing progresses too much, and the moldability and the curing property are poor.

  Moreover, the cured product obtained using the synthesized urethane prepolymer is poor in flexibility and inferior in impact resistance, and in the evaluation as a pressure-sensitive adhesive, the adhesive property is poor, and therefore, in the application having unevenness, the step to the step It could not be expected to follow up.

Comparative Example 3
A urethane prepolymer was synthesized by changing the polyol A6 of Comparative Example 2 to a polyol A7 having a low degree of unsaturation but a low molecular weight, and the properties were evaluated. Although the viscosity is low, the dispersibility in a solvent is poor and the handling property is poor, the pot life at the time of curing is short, the curing progresses too much, and the moldability and the curing property are poor.

  Moreover, the cured product obtained using the synthesized urethane prepolymer is poor in flexibility and inferior in impact resistance, and in the evaluation as a pressure-sensitive adhesive, the adhesive property is poor, and therefore, in the application having unevenness, the step to the step It could not be expected to follow up.

Comparative Example 4
A urethane prepolymer was synthesized by reducing the ratio of polyether diol A3 to isocyanate C1 of Example 3 from NCO / OH = 0.95 to 0.8, and the properties were evaluated. The viscosity and the handling property were good, but the pot life at the time of curing was short, and the curing progressed too much, resulting in poor formability and curability.

Comparative Example 5
The synthesis of the urethane prepolymer was investigated using only the trifunctional polyether polyol without using the polyether diol A. Although the reaction was completed, the viscosity rapidly increased in the late stage of the reaction to form a gel component insoluble in the solvent, making it difficult to use as a urethane prepolymer.

Comparative Example 6
A urethane prepolymer was synthesized using only the polyester polyol without using polyether diol A, and the properties were evaluated. The viscosity was high and the handling property was poor, the pot life at the time of curing was short, the curing progressed too much, and the moldability and curability were poor.
The cured product obtained by using the synthesized urethane prepolymer has good adhesion, but has poor flexibility and poor impact resistance, and has high glass transition temperature and adhesion reliability at low temperature. Could not be expected.

Claims (10)

A urethane prepolymer obtained using polyether diol A and polyisocyanate C, which is
The degree of unsaturation of the polyether diol A is 0.07 meq / g or less, and the number average molecular weight is 3,000 to 30,000, and the NCO group of the polyisocyanate C and the total amount of OH groups of the polyether diol A Ratio in the range of 0.85 to 1.15 (molar ratio)
A urethane prepolymer characterized in that the polyisocyanate C is at least one selected from the group consisting of aliphatic isocyanates, alicyclic isocyanates, and modified products thereof. The degree of unsaturation (meq / g) and the number average molecular weight of the polyether diol A are as follows:
Degree of unsaturation ≦ number average molecular weight × 0.00001
The urethane prepolymer according to claim 1, characterized in that The urethane prepolymer according to claim 1 or 2 , wherein the number average molecular weight (Mn) in terms of standard polystyrene is in the range of 30,000 to 300,000. The urethane prepolymer according to any one of claims 1 to 3 , wherein the polyether diol A is obtained by ring-opening polymerization of an alkylene oxide using an imino group-containing phosphazenium salt catalyst. polymer. A urethane prepolymer solution having a concentration of 10 to 90% by weight of the urethane prepolymer obtained using the urethane prepolymer according to any one of claims 1 to 4 and a solvent. A two-part curable polyurethane obtained by using the urethane prepolymer according to any one of claims 1 to 4 and a crosslinking agent D having reactivity with an active hydrogen group or an isocyanate group. The two-component polyurethane according to claim 6 , wherein the crosslinking agent D is used in a range of 2 to 20 equivalents (molar ratio) with respect to the reactive group of the urethane prepolymer. A urethane adhesive comprising the urethane prepolymer according to any one of claims 1 to 4 . A two-part curable urethane adhesive obtained by using the two-part curable polyurethane according to claim 6 or 7 . The adhesive sheet for optics obtained using the urethane adhesive of Claim 8 or 9 .