KR20210146336A - Cured product of urethane prepolymer composition and manufacturing method thereof, structure and manufacturing method thereof, and image display device - Google Patents

Abstract

Disclosed is a method for preparing a cured product of a urethane prepolymer composition including urethane prepolymer. The manufacturing method comprises the steps of: moisture curing a urethane prepolymer composition to obtain a first cured product of the urethane prepolymer composition; and heating the first cured product to obtain a second cured product of the urethane prepolymer composition process is provided. The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol.

Description

Cured product of urethane prepolymer composition and manufacturing method thereof, structure and manufacturing method thereof, and image display device

The present invention relates to a cured product of a urethane prepolymer composition, a method for producing the same, a structure and a method for producing the same, and an image display device.

Since the hot melt adhesive is a solvent-free adhesive, the load on the environment and the human body is small, and the adhesive is suitable for improving productivity because it can be adhered for a short time. The hot-melt adhesive can be roughly divided into two types, one containing a thermoplastic resin as a main component and one containing a reactive resin as a main component. As a reactive resin, the urethane prepolymer which has an isocyanate group at the terminal is mainly used.

A reactive hot melt adhesive containing urethane prepolymer as a main component exhibits some degree of adhesive strength in a short time by cooling and solidification of the adhesive itself after application. Thereafter, the terminal isocyanate group of the urethane prepolymer reacts with moisture (moisture in the air or on the surface of the adherend) to make it high in molecular weight, thereby exhibiting good adhesive strength by generating crosslinking. Moreover, in order to improve adhesiveness, impact resistance, etc., the reactive hot-melt adhesive composition containing the urethane prepolymer which has a crystalline polyol as a structural unit is also known (for example, refer patent document 1).

Patent Document 1: International Publication No. 2017/187968

However, according to the studies of the present inventors, when a crystalline polyol is introduced as a structural unit into the urethane prepolymer, the solidification rate of the urethane prepolymer tends to be improved, and workability tends to be good. In the phosphorus prepolymer cured product, it was found that the tensile modulus of the cured product was improved, it was easily cracked by impact, and the impact resistance was not sufficient.

Accordingly, in the present invention, in a urethane prepolymer composition comprising a urethane prepolymer having a structural unit derived from a crystalline polyol, a cured product of the urethane prepolymer composition with sufficiently reduced tensile modulus and a method for producing the same Its main purpose is to provide

As a result of intensive studies by the present inventors, in a urethane prepolymer composition comprising a urethane prepolymer having a structural unit derived from a crystalline polyol, heating is applied to the cured product of the urethane prepolymer composition obtained by moisture curing. When it carried out, it discovered the phenomenon that the tensile elasticity modulus was reduced, and came to complete this invention.

One aspect of the present invention relates to a method for preparing a cured product of a urethane prepolymer composition including the urethane prepolymer. Here, the urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. One aspect of the method for producing a cured product of the urethane prepolymer composition includes a step of moisture curing the urethane prepolymer composition to obtain a first cured product of the urethane prepolymer composition, heating the first cured product, A step of obtaining a second cured product of the retane prepolymer composition is provided.

The tensile modulus of elasticity of the 2nd hardened|cured material is lower than the tensile modulus of the 1st hardened|cured material, for example, 50% or less of the tensile modulus of the 1st hardened|cured material may be sufficient.

The crystalline polyol may contain the crystalline polyester polyol. The content of the structural unit derived from the crystalline polyol may be 5% by mass or more based on the total amount of the structural unit derived from the polyol.

Another aspect of the method for producing a cured product of the urethane prepolymer composition includes a step of heating a first cured product obtained by moisture curing the urethane prepolymer composition to obtain a second cured product of the urethane prepolymer composition do.

According to the manufacturing method of one aspect of this invention, it becomes possible to obtain the hardened|cured material of the urethane prepolymer composition whose tensile elasticity modulus was sufficiently reduced.

Another aspect of the present invention relates to a method for manufacturing a structure comprising a first adherend, a second adherend, and a cured product layer for adhering the first adherend and the second adherend to each other. The method for manufacturing the structure includes the steps of preparing a laminate in which a first adherend, a resin layer containing a urethane prepolymer composition containing urethane prepolymer, and a second adherend are laminated in this order; A step of moisture curing the urethane prepolymer composition in and heating to form a second cured product layer containing the second cured product of the urethane prepolymer composition. The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol.

Another aspect of the present invention relates to a cured product of a urethane prepolymer composition including the urethane prepolymer. The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. The cured product of the urethane prepolymer composition has a tensile modulus of 15 MPa or less.

Another aspect of the present invention relates to a structure. The structure includes a first adherend, a second adherend, and a cured product layer for adhering the first adherend and the second adherend to each other. The hardened|cured material layer contains the hardened|cured material of said urethane prepolymer composition.

Another aspect of the present invention provides an image display device having the above structure.

According to the present invention, in the urethane prepolymer composition comprising a urethane prepolymer having a structural unit derived from a crystalline polyol, there is provided a cured product of the urethane prepolymer composition with sufficiently reduced tensile modulus and a method for producing the same do. Moreover, according to this invention, the structure using the hardened|cured material of such a urethane prepolymer composition, and its manufacturing method are provided. Further, according to the present invention, an image display apparatus using such a structure is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a piece logarithm graph which shows the change of the tensile elasticity modulus with respect to the heating time of the 1st hardened|cured material of Example 1. FIG.
2 is a logarithmic graph showing the change in tensile modulus of the second cured product of Example 1 with respect to the elapsed time at room temperature.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described. However, this invention is not limited to the following embodiment.

In the present specification, "polyol" means a compound having two or more hydroxyl groups in a molecule.

In this specification, "polyisocyanate" means a compound having two or more isocyanate groups in a molecule.

[Method for producing cured product of urethane prepolymer composition]

In the method for producing a cured product of a urethane prepolymer composition of one embodiment, a step of moisture curing the urethane prepolymer composition to obtain a first cured product of the urethane prepolymer composition (hereinafter referred to as a “first step”) ) and a step of heating the first cured product to obtain a second cured product of the urethane prepolymer composition (hereinafter, sometimes referred to as a “second step”).

<First step>

The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. The urethane prepolymer includes a polymer chain comprising a structural unit derived from a polyol comprising a structural unit derived from a crystalline polyol, and a structural unit derived from a polyisocyanate, and is a terminal group of the polymer chain. You may have an isocyanate group. The urethane prepolymer is, for example, a reaction product of a polyol containing a crystalline polyol and a polyisocyanate, and may have an isocyanate group as a terminal group of the reaction product. In general, a urethane prepolymer composition containing a urethane prepolymer has a property of mainly increasing the molecular weight of the urethane prepolymer and curing it by moisture by reacting with moisture in the air or moisture on the surface of an adherend.

The polyol which provides the structural unit derived from a polyol contains a crystalline polyol. In this case, the urethane prepolymer consists of a structural unit derived from a crystalline polyol, a structural unit derived from a polyol other than the crystalline polyol (that is, an amorphous polyol), and a polyisocyanate. It may include a polymer chain including a structural unit derived from it. In addition, here, the determination of crystallinity can be determined by the state at 25 degreeC. The crystalline polyol means a polyol that is crystalline at 25°C, and the non-crystalline polyol (amorphous polyol) means a polyol that is amorphous at 25°C. In addition, the determination of crystallinity can also be judged by the presence or absence of melting|fusing point Tm (an endothermic peak accompanying melting in DSC).

The crystalline polyol can be used without particular limitation as long as it has two or more hydroxyl groups and is a crystalline compound at 25°C. Examples of the crystalline polyol include crystalline polyester polyol, crystalline polycarbonate polyol, and crystalline polycaprolactone polyol. These crystalline polyols may be used individually by 1 type, and may be used in combination of 2 or more type.

Among these, the crystalline polyol may contain the crystalline polyester polyol. When the polymer chain includes the structural unit derived from the crystalline polyester polyol, the solidification time and the viscosity of the urethane prepolymer composition can be adjusted. The crystalline polyester polyol is a polyester polyol produced by a polycondensation reaction of a polyhydric alcohol and a polycarboxylic acid, and a polyester polyol that is crystalline at 25°C can be selected and used. The polyester polyol has, for example, a polyhydric alcohol having 2 to 15 carbon atoms and 2 or 3 hydroxyl groups, 2 to 14 carbon atoms (including carbon atoms in a carboxyl group), and 2 to 6 carbon atoms. Polycondensate with polycarboxylic acid which has a carboxyl group may be sufficient.

The polyester polyol may be a straight-chain polyester diol produced from a diol and dicarboxylic acid, or a branched polyester triol produced from a triol and a dicarboxylic acid. Moreover, a branched polyester triol can also be obtained by reaction of a diol and tricarboxylic acid.

Examples of the polyhydric alcohol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, each isomer of butanediol, each isomer of pentanediol, and hexanediol. Each isomer of the ol, 2,2-dimethyl-1,3-propanediol, 2-methylpropanediol, 2,4,4-trimethyl-1,6-hexanediol, 2,2 aliphatic or alicyclic diols such as ,4-trimethyl-1,6-hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; and aromatic diols such as 4,4'-dihydroxydiphenylpropane, bisphenol A, bisphenol F, pyrocatechol, resocinol, and hydroquinone. A polyhydric alcohol may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, aliphatic diols are preferred, and aliphatic diols having 2 to 6 carbon atoms are more preferred.

Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid and 1,2,4-benzene tricarboxylic acid; Maleic acid, fumaric acid, aconitic acid, 1,2,3-propanetricarboxylic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, cyclohexane-1,2 and aliphatic or alicyclic polycarboxylic acids such as -dicarboxylic acid and 1,4-cyclohexanediene-1,2-dicarboxylic acid. Polycarboxylic acid may be used individually by 1 type, and may be used in combination of 2 or more type.

Instead of the polycarboxylic acid described above, a polycarboxylic acid derivative such as a carboxylic acid anhydride or a compound in which a part of a carboxyl group is esterified may be used. Examples of the polycarboxylic acid derivative include dodecyl maleic acid and octadecenyl maleic acid.

The number average molecular weight (Mn) of the crystalline polyester polyol is preferably in the range of 500 to 10000, more preferably in the range of 800 to 9000, still more preferably in the range of 1000 to 8000, from the viewpoint of improving water resistance and adhesive strength. is the range of In addition, in this specification, the number average molecular weight (Mn) is the value measured by gel permeation chromatography (GPC) and converted into standard polystyrene. The measurement of GPC can be performed under the following conditions.

Column: "Gelpack GLA130-S", "Gelpack GLA150-S" and "Gelpack GLA160-S" (manufactured by Hitachi Kasei Co., Ltd., packed column for HPLC)

Eluent: tetrahydrofuran

Flow rate: 1.0 mL/min

Column temperature: 40°C

Detector: RI

The content of the structural unit derived from the crystalline polyol may be 5% by mass or more, 8% by mass or more, or 10% by mass or more based on the total amount of the structural unit derived from the polyol. When the content of the structural unit derived from the crystalline polyol is 5% by mass or more based on the total amount of the structural unit derived from the polyol, a second cured product described later having a desired tensile modulus tends to be easily obtained. The content of the structural unit derived from the crystalline polyol is 80% by mass or less, 60% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less based on the total amount of structural units derived from the polyol. , 35 mass % or less, or 30 mass % or less may be sufficient. If it is 80 mass % or less based on the total amount of structural units derived from a polyol, it exists in the tendency excellent in workability|operativity.

The crystalline polyol may contain polyols other than the crystalline polyester polyol.

The polyol may contain an amorphous polyol. Examples of the amorphous polyol include amorphous polyester polyol and polyether polyol. The amorphous polyester polyol is a polyester polyol produced by a polycondensation reaction of a polyhydric alcohol and a polycarboxylic acid. At 25° C., a non-crystalline polyester polyol can be selected and used.

Examples of the amorphous polyester polyol include an amorphous polyester polyol having a number average molecular weight (Mn) of 3000 or less, and an amorphous polyester polyol having a number average molecular weight (Mn) of 5000 or more. Mn of the amorphous polyester polyol having Mn of 3000 or less is preferably in the range of 500 to 3000, more preferably in the range of 1000 to 3000, from the viewpoint of improving the adhesive strength of the urethane prepolymer composition. Mn of the amorphous polyester polyol having Mn of 5000 or more is preferably in the range of 5000 to 9000, more preferably in the range of 7000 to 8000, from the viewpoint of improving the impact resistance.

Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, and ethylene oxide-modified polypropylene glycol.

Mn of the polyether polyol is preferably in the range of 500 to 5000, more preferably in the range of 700 to 4500, still more preferably from the viewpoint of initial adhesive strength, adhesive strength after curing, and appropriate open time after application. It ranges from 1000 to 4000. A polyether polyol may be used individually by 1 type, and may be used in combination of 2 or more type.

The amorphous polyol may contain polyols other than the amorphous polyester polyol and polyether polyol.

Polyisocyanate can be used without a restriction|limiting in particular, as long as it is a compound which has two or more isocyanate groups. As polyisocyanate, for example, diphenylmethane diisocyanate, dimethyl diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, p - Aromatic isocyanate, such as phenylene diisocyanate; alicyclic isocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate; Aliphatic isocyanate, such as hexamethylene diisocyanate, etc. are mentioned. From the viewpoint of reactivity and adhesiveness, polyisocyanate, Preferably aromatic diisocyanate is contained, More preferably, diphenylmethane diisocyanate is contained. Polyisocyanate may be used individually by 1 type, and may be used in combination of 2 or more type.

A urethane prepolymer can be synthesize|combined by making a polyol and polyisocyanate react.

The urethane prepolymer preferably comprises a polymer chain comprising a structural unit derived from a polyol comprising a structural unit derived from a crystalline polyol and a structural unit derived from a polyisocyanate, the end of the polymer chain It has an isocyanate group as a short term. When synthesizing such a urethane prepolymer, the ratio of the isocyanate group (NCO) equivalent of the polyisocyanate to the hydroxyl group (OH) of the polyol containing the crystalline polyol (isocyanate of the polyisocyanate) Cyanate group (NCO) equivalent/hydroxyl group (OH) equivalent of polyol, NCO/OH) is larger than 1, Preferably it is 1.5-3.0, More preferably, it is 1.8-2.5. When ratio of NCO/OH is 1.5 or more, it suppresses that the viscosity of the urethane prepolymer obtained becomes high too much, and there exists a tendency for workability|operativity to improve easily. When the ratio of NCO/OH is 3.0 or less, foaming hardly occurs at the time of the moisture curing reaction of the urethane prepolymer composition, and there is a tendency to easily suppress a decrease in adhesive strength.

Although the urethane prepolymer composition may consist of a urethane prepolymer, it may contain other components as needed.

The urethane prepolymer composition may further contain a catalyst from a viewpoint of promoting hardening of a urethane prepolymer and expressing higher adhesive strength. Examples of the catalyst include dibutyltin dilaurate, dibutylthionoctate, dimethylcyclohexylamine, dimethylbenzylamine, and trioctylamine. The content of the catalyst may be 0.01 to 1% by mass based on the total amount of the urethane prepolymer composition.

The urethane prepolymer composition may further contain a thermoplastic polymer from the viewpoint of increasing the rubber elasticity of the formed cured product and further improving the impact resistance. Examples of the thermoplastic polymer include polyurethane, ethylene-based copolymer, propylene-based copolymer, vinyl chloride-based copolymer, acrylic copolymer, and styrene-conjugated diene block copolymer. The content of the thermoplastic polymer may be 1 to 20 mass% based on the total amount of the urethane prepolymer composition.

The urethane prepolymer composition may further contain tackifying resin from a viewpoint of providing stronger adhesiveness to the hardened|cured material formed. As tackifying resin, For example, rosin resin, rosin ester resin, hydrogenated rosin ester resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, petroleum resin, hydrogenated petroleum resin, coumarone resin, ketone resin, stein Ren resin, modified styrene resin, xylene resin, an epoxy resin, etc. are mentioned. Content of tackifying resin may be 1-20 mass % on the basis of urethane prepolymer composition whole quantity.

The urethane prepolymer composition may contain an antioxidant, a pigment, a ultraviolet absorber, a surfactant, a flame retardant, a filler, etc. in an appropriate amount as needed.

Then, the urethane prepolymer composition is moisture-cured, and a 1st hardened|cured material is obtained. The conditions for producing the first cured product may be the same as the conditions for moisture curing the normal reactive hot-melt adhesive. The first cured product, for example, melts the urethane prepolymer composition at 80 to 180° C., produces a film having a thickness of 10 to 500 μm by application or the like, and then heats the film at a temperature of 10 to 35° C., preferably A temperature of 15 to 30°C, more preferably a temperature of 20 to 25°C, and a relative humidity of 30% or more, preferably 30 to 70%, can be obtained by moisture curing in 12 to 168 hours.

Although the tensile modulus in particular of 1st hardened|cured material is not restrict|limited, More than 15 MPa and 100 MPa or less may be sufficient. More than 15 MPa, 25 MPa or more, or 35 MPa or more may be sufficient as the tensile elasticity modulus of 1st hardened|cured material, 100 MPa or less, 80 MPa or less, or 60 MPa or less may be sufficient as it. In addition, in this specification, the tensile modulus means the value measured by the method described in an Example.

<Second process>

Next, the 1st hardened|cured material is heated and the 2nd hardened|cured material is obtained. In this specification, the hardened|cured material of a urethane prepolymer composition means 2nd hardened|cured material. Generally, the tensile modulus of elasticity of a 1st hardened|cured material tends to fall by heating at the temperature exceeding the crystal melting point of the crystal component contained in 1st hardened|cured material. That is, from the change (reduction) of the tensile modulus of the first cured product, the production of the second cured product is suggested, and what shows a tensile modulus of elasticity lower than that of the first cured product can be defined as a second cured product. Although the heating temperature of 1st hardened|cured material can be set suitably according to the crystal melting point of a crystal component, 60 degreeC or more may be sufficient and 80 degreeC or more may be sufficient, for example. Although the heating time of 1st hardened|cured material can be set suitably according to the fall of the tensile elasticity modulus, 2 minutes or more may be sufficient, 10 minutes or more, or 1 hour or more may be sufficient, for example.

The second cured product may have a lower tensile modulus of elasticity than that of the first cured product. The tensile modulus of elasticity of the second cured product may be, for example, 50% or less, 45% or less, 40% or less, or 35% or less of the tensile elastic modulus of the first cured product. When the tensile modulus of elasticity of the second cured product is 50% or less of the tensile modulus of the first cured product, it tends to be excellent in impact resistance and stress relaxation properties.

Although the reason why the tensile elasticity modulus is reduced by heating 1st hardened|cured material and the 2nd hardened|cured material is produced|generated is not necessarily clear, the present inventors think as follows. The urethane prepolymer contained in the urethane prepolymer composition has a structural unit derived from a polyol whose polymer chain includes a structural unit derived from a crystalline polyol. Therefore, when the urethane prepolymer composition is melted and a film is formed by application or the like, crystallization of the crystalline polyol proceeds with a decrease in temperature to form a crystal part. Thereafter, the first cured product obtained by moisture curing tends to have an improved tensile modulus compared to that without the crystal part because the crystal part loses flexibility. On the other hand, when the first cured product is heated, it is expected that the intermolecular interaction of the crystal part is weakened, and accordingly, it is considered that the second cured product exhibits a lower tensile modulus of elasticity than that of the first cured product. In addition, since the molecular weight (number average molecular weight) of the second cured product is significantly increased due to urethaneization compared to when the urethane prepolymer composition is melted, even when left at room temperature (23° C.), It is expected that the progress of crystallization is suppressed again. Therefore, although the tensile modulus is gradually restored by leaving it to stand at room temperature (23°C), it is considered that it takes time in years to restore to a tensile modulus of 50% of the tensile modulus of the first cured product.

According to the present invention, in a urethane prepolymer composition comprising a urethane prepolymer having a structural unit derived from a crystalline polyol, when a cured product of the urethane prepolymer composition obtained by moisture curing is heated, the tensile modulus of elasticity It is in finding out the phenomenon that this is reduced. Therefore, the manufacturing method of the hardened|cured material of a urethane prepolymer composition is another embodiment, heating the 1st hardened|cured material obtained by moisture-curing a urethane prepolymer composition, and obtaining the 2nd hardened|cured material of a urethane prepolymer composition It may be to provide a process.

[Method for manufacturing structure]

A method for manufacturing a structure according to an embodiment is a method for manufacturing a structure comprising a first adherend, a second adherend, and a cured product layer for adhering the first adherend and the second adherend to each other. The method for manufacturing the structure includes a step of preparing a laminate in which a first adherend, a resin layer containing a urethane prepolymer composition containing urethane prepolymer, and a second adherend are laminated in this order (hereinafter referred to as " A step (sometimes referred to as “step A”), and a step of moisture curing the urethane prepolymer composition in the resin layer to form a first cured product layer containing the first cured product of the urethane prepolymer composition ( Hereinafter, it may be referred to as "Step B.") and the second cured material layer containing the second cured material of the urethane prepolymer composition by heating the first cured material layer in the first cured material layer. A step of forming (hereinafter, sometimes referred to as “step C”) is provided. The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. Here, a hardened|cured material layer has the same meaning as a 2nd hardened|cured material layer.

<Process A>

First, a laminate is prepared in which a first adherend, a resin layer containing a urethane prepolymer composition containing a urethane prepolymer, and a second adherend are laminated in this order. In addition, since the resin layer is a thing which can express adhesiveness by cooling and solidification of a urethane prepolymer composition, in a laminated body, a 1st to-be-adhered body and a 2nd to-be-adhered body may be adhered by the resin layer. Examples of the first adherend and the second adherend include metal substrates such as SUS and aluminum, and non-metal substrates such as polycarbonate, polyamide, glass, wood, cloth, and leather. The first adherend and the second adherend may be the same as or different from each other.

The laminate includes, for example, a step of forming a resin layer on at least one of the first adherend and the second adherend using the urethane prepolymer composition described above, and the first adherend with the first adherend through the resin layer. It can be obtained by a manufacturing method including the process of crimping|bonding a 2nd to-be-adhered body. The resin layer can be formed by, for example, coating the urethane prepolymer composition described above by melting. Moreover, after melt|dissolving the urethane prepolymer composition mentioned above, for example, a resin layer can produce a film by application|coating on support films, such as polyethylene terephthalate, and can also form it using the said film. Although the application method of a urethane prepolymer composition is not specifically limited, For example, the method of using a dispenser is mentioned. The melting temperature of the urethane prepolymer composition may be, for example, 80 to 180°C. When forming a resin layer using a film, 10-500 micrometers may be sufficient as the thickness of a film, for example. Although the method in particular of crimping|bonding a 1st to-be-adhered body and a 2nd to-be-adhered body via a resin layer is not restrict|limited, For example, the method of crimping|bonding using a pressure roll etc. is mentioned.

<Process B>

Next, the urethane prepolymer composition in the resin layer in the laminate is subjected to moisture curing to form a first cured product layer containing the first cured product of the urethane prepolymer composition. Conditions for forming the first cured material layer may be the same as those for obtaining the above-described first cured material layer, for example. That is, the laminate is heated at a temperature of 10 to 35° C., preferably at a temperature of 15 to 30° C., more preferably at a temperature of 20 to 25° C. and a relative humidity of 30% or more, preferably from 12 to 70% in an environment of 30 to 70%. The first cured product layer containing the first cured product of the urethane prepolymer composition can be formed by moisture curing at 168 hours.

<C process>

Next, the 1st hardened|cured material in the 1st hardened|cured material layer in a laminated body is heated, and the 2nd hardened|cured material layer containing the 2nd hardened|cured material of a urethane prepolymer composition is formed. The conditions for forming the second cured material layer may be the same as those for obtaining the above-described second cured material layer, for example. That is, urethane is obtained by heating a laminate including a first cured material layer containing a first cured material at a heating temperature of 60°C or higher or 80°C or higher for 2 minutes or more, 10 minutes or more, or 1 hour or more. A second cured material layer containing the second cured material of the prepolymer composition may be formed.

As described above, the second cured product may exhibit a lower tensile modulus of elasticity than that of the first cured product. The tensile modulus of elasticity of the second cured product may be, for example, 50% or less, 45% or less, 40% or less, or 35% or less of the tensile elastic modulus of the first cured product.

According to the manufacturing method including these steps, a structure including a first adherend, a second adherend, and a cured product layer for adhering the first adherend and the second adherend to each other can be obtained.

[Cured product of urethane prepolymer composition]

In the cured product of the urethane prepolymer composition of one embodiment, the urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol, and has a tensile modulus of 15 MPa or less.

The cured product of the urethane prepolymer composition means a second cured product. The tensile modulus of elasticity of the cured product (second cured product) of the urethane prepolymer composition is 15 MPa or less, and may be 13 MPa or less, 10 MPa or less, or 8 MPa or less. When the tensile modulus of elasticity of the second cured product is 15 MPa or less, the second cured product tends to be excellent in impact resistance and stress relaxation properties. The tensile modulus of elasticity of the second cured product may be 1 MPa or more, 3 MPa or more, or 5 MPa or more.

The crystalline polyol may contain the crystalline polyester polyol. The content of the structural unit derived from the crystalline polyol may be 5% by mass or more based on the total amount of the structural unit derived from the polyol.

The cured product of the urethane prepolymer composition can adhere various types of adherends therethrough. The cured product of the urethane prepolymer composition has excellent impact resistance since the tensile modulus of elasticity is sufficiently reduced.

[Structure and image display device]

A structure according to an embodiment includes a first adherend, a second adherend, and a cured product layer for adhering the first adherend and the second adherend to each other, and the cured product layer includes the urethane prepolymer described above. A cured product of the composition is contained. As the first adherend and the second adherend, the same ones as those exemplified in the above-described first adherend and second adherend can be exemplified.

The image display apparatus of one embodiment is provided with the structure of this embodiment. As an image display apparatus, For example, a plasma display (PDP), a liquid crystal display (LCD), a cathode ray tube (CRT), a field emission display (FED), an organic electroluminescent display (OELD), a 3D display, an electronic paper (EP), etc. can be heard

Example

Hereinafter, although this invention is concretely demonstrated based on an Example, this invention is not limited to these.

(Example 1)

<Preparation of urethane prepolymer>

The polyol (A) previously dehydrated was added to the reaction vessel in the amount (parts by mass) shown in Table 1, and mixed uniformly. Next, the polyisocyanate (B) is further added to the reaction vessel in the amount (parts by mass) shown in Table 1, mixed uniformly, reacted at 110°C for 1 hour, and again at 110°C for 1 hour under reduced pressure defoaming.泡) By stirring, the urethane prepolymer of Example 1 was prepared. Since the obtained urethane prepolymer has a (NCO) equivalent/(OH) equivalent larger than 1 as shown in Table 1, it is estimated that it has an isocyanate group as a terminal group of a polymerization chain. The obtained urethane prepolymer was used for preparation of the 1st hardened|cured material as the urethane prepolymer composition of Example 1.

(Polyol (A))

A1: Crystalline polyester polyol containing adipic acid and 1,6-hexanediol as main components (number of hydroxyl groups: 2, number average molecular weight 5000)

A2: Crystalline polyester polyol containing adipic acid and 1,6-hexanediol as main components (number of hydroxyl groups: 2, number average molecular weight 3000)

A3: Amorphous polyester polyol containing adipic acid and ethylene glycol as main components (number of hydroxyl groups: 2, number average molecular weight of 2000)

A4: Amorphous polyester polyol containing isophthalic acid and ethylene glycol as main components (number of hydroxyl groups: 2, number average molecular weight: 2000)

A5: Amorphous polyester polyol containing isophthalic acid and neopentyl glycol as main components (number of hydroxyl groups: 2, number average molecular weight: 2000)

A6: polypropylene glycol (polyether polyol (amorphous), number of hydroxyl groups: 2, number average molecular weight: 2000)

(Polyisocyanate (B))

B1: diphenylmethane diisocyanate (number of isocyanate groups: 2)

<Production of first cured product>

After melting the urethane prepolymer composition at 100 ° C. to form a film having a thickness of 100 µm, the film is subjected to moisture curing by standing in a constant temperature and humidity chamber at a temperature of 23 ° C. and a humidity of 50% for 24 hours. 1 A cured product was obtained.

<Measurement of tensile modulus of first cured product>

The first cured product was punched out with a No. 1 dumbbell to prepare a test piece, and the tensile modulus (MPa) of the test piece was measured in accordance with JIS K-7127 using Autograph AGS-X (manufactured by Shimadzu Corporation). The tensile modulus of elasticity of the 1st hardened|cured material was 26.4 MPa.

<Production of second cured product>

The test piece of the 1st hardened|cured material obtained above was heated at 60 degreeC using the heat dryer. BRIEF DESCRIPTION OF THE DRAWINGS It is a piece-logarithm graph which shows the change of the tensile elasticity modulus with respect to the heating time of the 1st hardened|cured material of Example 1. FIG. The tensile modulus of elasticity after 2 minutes of heating of the 1st hardened|cured material was 4.9 MPa, and the tensile modulus of elasticity after 60 minutes of heating was 2.0 MPa. These values were 50% or less with respect to the tensile modulus of elasticity of the 1st hardened|cured material before heating. Generation of a 2nd hardened|cured material was suggested from such a physical-property change.

<Observation of tensile modulus of second cured product>

The test piece of the 2nd hardened|cured material (1st hardened|cured material after heating 60 minutes) was left to stand at room temperature (23 degreeC). The tensile modulus of elasticity after the lapse of 48 hours of the second cured product was 6.9 MP, and the tensile modulus of elasticity after progress of 1100 hours was 11.2 MP. Fig. 2 is a logarithmic graph showing the change in tensile modulus of the second cured product of Example 1 with respect to the elapsed time at room temperature. As shown in FIG. 2 , the tensile modulus of elasticity of the second cured product tends to be restored (improved) over time, but the restoration time estimated from the approximate curve is 50% of the tensile modulus of the first cured product. It was found that the time to restore to (13.2 MPa) was approximately 1.5 years, and the time to restore to 100% (26.4 MPa) was approximately 50,000 years.

[Table 1]

(Examples 2-1 to 2-5)

<Preparation of urethane prepolymer composition>

The polyol (A) containing the crystalline polyol previously dehydrated was added to the reaction vessel in the amount (parts by mass) shown in Table 2, and mixed uniformly. Next, the polyisocyanate (B) is further added to the reaction vessel in the amount (parts by mass) shown in Table 1, mixed uniformly, reacted at 110° C. for 1 hour, and again stirred at 110° C. under reduced pressure for 1 hour. , a urethane prepolymer was prepared. In addition, as for the polyol (A) and the polyisocyanate (B), the thing similar to what was described in Example 1 was used. As shown in Table 2, the obtained urethane prepolymer has (NCO) equivalent/(OH) equivalent larger than 1, so that it is estimated that it has an isocyanate group as a terminal group of a polymerization chain. (C) Acrylic copolymer was added with respect to the obtained urethane prepolymer in the compounding quantity (mass part) shown in Table 2, and the urethane prepolymer composition of Examples 2-1 to 2-5 was obtained.

(Acrylic copolymer (C))

C1: Acrylic copolymer containing butyl acrylate and methyl methacrylate as main components (number average molecular weight 100000)

<Production of first cured product>

Each of the urethane prepolymer compositions of Examples 2-1 to 2-5 was melted at 100° C. to form a film having a thickness of 100 μm, and then the film was stored in a thermo-hygrostat at a temperature of 23° C. and a humidity of 50% for 24 hours. Moisture hardening was carried out by leaving still, and the 1st hardened|cured material was obtained. It carried out similarly to Example 1, the test piece was produced, and the tensile modulus of elasticity of the test piece was measured. A result is shown in Table 2.

<Production of second cured product>

The test piece of the 1st hardened|cured material obtained above was heated at 80 degreeC using the heat dryer, and the tensile modulus of elasticity of the 1st hardened|cured material after heating 10 minutes was measured. A result is shown in Table 2. Generation of a 2nd hardened|cured material was suggested from such a physical-property change.

[Table 2]

As described above, the production of the second cured product was suggested by heating the first cured product formed by moisture curing the urethane prepolymer composition containing the urethane prepolymer having a structural unit derived from the crystalline polyol. Moreover, it was confirmed that the tensile modulus of elasticity of the 2nd hardened|cured material was sufficiently reduced with respect to the tensile modulus of elasticity of the 1st hardened|cured material.

Claims (16)

A method for producing a cured product of a urethane prepolymer composition comprising urethane prepolymer, the method comprising:
Moisture curing the urethane prepolymer composition to obtain a first cured product of the urethane prepolymer composition;
heating the first cured product to obtain a second cured product of the urethane prepolymer composition;
A method for producing a cured product of a urethane prepolymer composition, wherein the urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. The method according to claim 1,
A method for producing a cured product of a urethane prepolymer composition, wherein the second cured product has a lower tensile modulus of elasticity than the first cured product. The method according to claim 1 or 2,
The method for producing a cured product of the urethane prepolymer composition, wherein the second cured product has a tensile modulus of elasticity of 50% or less of a tensile modulus of the first cured product. 4. The method according to any one of claims 1 to 3,
The method for producing a cured product of a urethane prepolymer composition, wherein the crystalline polyol contains a crystalline polyester polyol. 5. The method according to any one of claims 1 to 4,
The method for producing a cured product of a urethane prepolymer composition, wherein the content of the structural unit derived from the crystalline polyol is 5% by mass or more based on the total amount of the structural unit derived from the polyol. A method for manufacturing a structure, comprising: a first adherend; a second adherend; and a cured product layer for adhering the first adherend and the second adherend to each other;
preparing a laminate in which the first adherend, a resin layer containing a urethane prepolymer composition containing urethane prepolymer, and the second adherend are laminated in this order;
a step of moisture curing the urethane prepolymer composition in the resin layer to form a first cured product layer containing a first cured product of the urethane prepolymer composition;
heating the first cured product in the first cured product layer to form a second cured product layer containing a second cured product of the urethane prepolymer composition;
The method for producing a structure, wherein the urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. 7. The method of claim 6,
The second cured product has a tensile modulus of elasticity lower than that of the first cured product, the method of manufacturing a structure. 8. The method according to claim 6 or 7,
The second cured product has a tensile modulus of elasticity of 50% or less of a tensile modulus of the first cured product, the method of manufacturing a structure. A cured product of a urethane prepolymer composition comprising a urethane prepolymer,
The urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol,
A cured product of a urethane prepolymer composition having a tensile modulus of 15 MPa or less. 10. The method of claim 9,
The cured product of the urethane prepolymer composition, wherein the crystalline polyol includes a crystalline polyester polyol. 11. The method according to claim 9 or 10,
The cured product of the urethane prepolymer composition, wherein the content of the structural unit derived from the crystalline polyol is 5% by mass or more based on the total amount of the structural unit derived from the polyol. a first adherend;
a second adherend;
a cured material layer for bonding the first adherend and the second adherend to each other;
The structure in which the said hardened|cured material layer contains the hardened|cured material of the urethane prepolymer composition in any one of Claims 9-11. An image display device comprising the structure according to claim 12 . A method for producing a cured product of a urethane prepolymer composition comprising urethane prepolymer, the method comprising:
heating a first cured product obtained by moisture curing the urethane prepolymer composition to obtain a second cured product of the urethane prepolymer composition;
A method for producing a cured product of a urethane prepolymer composition, wherein the urethane prepolymer has a structural unit derived from a polyol including a structural unit derived from a crystalline polyol. 15. The method of claim 14,
A method for producing a cured product of a urethane prepolymer composition, wherein the second cured product has a lower tensile modulus of elasticity than the first cured product. 16. The method of claim 14 or 15,
The method for producing a cured product of the urethane prepolymer composition, wherein the second cured product has a tensile modulus of elasticity of 50% or less of a tensile modulus of the first cured product.

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