JP5558257B2 - Curable composition - Google Patents

Description

  The present invention relates to a curable composition containing urethane (meth) acrylate and capable of forming a cured product particularly excellent in scratch resistance and molding processability.

  Conventionally, in order to protect the base material of a molded product and maintain aesthetics, the base material is coated with a coating agent, and various materials are used for the coating agent.

  Among them, urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, etc., which have the property of being cured by active energy rays such as ultraviolet rays and electron beams, have been used as coating agents. It is known that (meth) acrylate forms an excellent film that is tough, has high mechanical strength, and is resistant to chemicals. Therefore, urethane (meth) acrylate is used in various fields as a main component of various types of coating agents that are cured with active energy rays.

In recent years, carbonate polyol has attracted attention as a polyol compound that is a material of this urethane (meth) acrylate. This is because urethane (meth) acrylates obtained using carbonate polyol are mechanical properties, hydrolysis resistance, heat resistance, chemical resistance, weather resistance compared to those using polyether polyol or polyester polyol. It is because it is excellent in.

  Examples of such urethane (meth) acrylates using carbonate polyols as raw materials include polycarbonate diols using 1,5-pentanediol and 1,6-hexanediol as raw materials, organic isocyanates, and hydroxy unsaturated compounds. The urethane (meth) acrylate used is disclosed, and the cured product of the urethane (meth) acrylate is characterized by high elongation and high strength (see Patent Document 1). Further, urethane (meth) acrylate comprising a polycarbonate diol having a number average molecular weight of 250 to 850, a diisocyanate compound, and a hydroxyl group-containing (meth) acrylic acid ester is disclosed. ) A cured product that exhibits silver protection performance is provided by mixing with an acrylic ester (see Patent Document 2). In addition, as a material of a curable composition having excellent physical property balance such as oil resistance, sweat resistance, hydrolysis resistance, weather resistance, flexibility, and adhesion, it is derived from an alcohol containing 2-methyl-1,3-propanediol. A urethane (meth) acrylate comprising a polycarbonate diol, a hydroxyl group-containing (meth) acrylate, and an isocyanate compound is disclosed (see Patent Document 3). Also disclosed is a urethane acrylate comprising a polycarbonate polyol having an alicyclic structure, an organic polyisocyanate, and a hydroxyl group-containing (meth) acrylate as a material for a curable composition having excellent chemical resistance and flexibility. (See Patent Document 4).

JP-A-6-166737 JP 2005-171154 A JP 2008-37989 A JP 2009-227915 A

When forming a protective film using a composition containing urethane (meth) acrylate, a method of performing a curing treatment after directly applying a liquid composition to the substrate surface, and first curing the composition into a sheet shape, Thereafter, there is a method of sticking the cured product to the substrate surface. In the former case, the elongation of the cured product is hardly a problem, but in the latter case, the cured product is used as a base material in addition to high scratch resistance to prevent the cured product from being damaged. Therefore, the cured product is required to have a large elongation required for molding such as vacuum molding. However, since the urethane (meth) acrylate described in Patent Documents 1 to 4 is premised on the use of the former method, any document has excellent scratch resistance and has a large elongation necessary for molding. A curable composition containing urethane (meth) acrylate capable of obtaining a cured product is not shown.
Then, this invention makes it a subject to obtain the sclerosing | hardenable composition which can form the hardened | cured material which is excellent in abrasion resistance and excellent in the molding processability in a sheet form.

In order to solve the above problems, the present invention has the following configuration.
The urethane (meth) acrylate of the present invention has a number average molecular weight obtained by reacting (a) a polycarbonate diol having a number average molecular weight of 400 to 600, (b) isophorone diisocyanate, and (c) 2-hydroxyethyl acrylate. 5,000 to 30,000 urethane (meth) acrylate , and the cured product has no yield point and the elongation at break is 100% or more in the tensile stress-strain curve diagram measured at 23 ° C. Features.

  Since the cured product of the curable composition of the present invention does not have a yield point, when the applied stress is within the elastic limit, it is restored to its original shape when released from the stress, and deformation does not occur. This means that when an external force that causes scratches is applied to the surface of the cured product, the external force is absorbed when the cured product dents (extends), and when the external force is removed, it returns to its original shape. This means that it does not remain and no flaws are formed. Moreover, since the elongation at break at 23 ° C. is 100% or more, the ability to avoid formation of scratches is high by stretching when an external force is applied. That is, it can be said that the allowable limit with respect to the external force of cured | curing material is high, and is excellent in abrasion resistance. Moreover, since the cured product of the curable composition of the present invention can have an elongation at break of 100% or more at a high temperature of 150 ° C., it is suitable for molding processing involving heating such as vacuum molding.

  Moreover, it is preferable that the number average molecular weight of polycarbonate diol is 400-600 in the curable composition of this invention. The cured product of the curable composition has a higher elongation at break and excellent scratch resistance.

  The polycarbonate diol is preferably composed of 3-methyl-1,5-pentanediol and 1,6-hexanediol. The cured product of the curable composition has a higher elongation at break and is superior in scratch resistance.

  Moreover, the content rate of the urethane (meth) acrylate in the curable composition of this invention is the weight except a solvent, and it is preferable that it is 50-100 weight%. When the content of urethane (meth) acrylate is less than 50% by weight, the cured product of the curable composition tends to have a yield point in the tensile stress-strain curve diagram, and as a result, the scratch resistance tends to decrease. It is in.

  According to the curable composition of the present invention, it is possible to obtain a cured product having not only scratch resistance but also excellent molding processability, thereby enabling molding such as vacuum molding. In addition, since the cured product has high adhesion to the substrate and has properties such as contamination resistance, chemical resistance, and weather resistance, the substrate is coated from the external environment by coating the substrate with the cured product. Can be properly protected.

1 is a tensile stress-strain curve diagram in Example 1. FIG. 6 is a tensile stress-strain curve diagram in Comparative Example 2. FIG.

Hereinafter, the present invention will be described in detail.
The curable composition of the present invention is a urethane (meth) acrylate obtained by reacting (a) a polycarbonate diol, (b) an alicyclic diisocyanate, and (c) a hydroxyl group-containing (meth) acrylic ester. Containing.
In this specification, the term “(meth) acrylate” is a general term for “acrylate” and “methacrylate”. Similarly, the term “(meth) acrylic acid” is a general term for “acrylic acid” and “methacrylic acid”, and the term “(meth) acryloyloxy group” is “acryloyloxy group” and “methacryloxy group”. Is a general term.

<(A) Polycarbonate diol>
Component (a) is a polycarbonate diol having two hydroxyl groups in the molecule, and can be obtained by a transesterification reaction between a diol compound and a carbonate. Specific examples of the diol compound include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol. 1,10-decanediol, 2-methyl-1,3-propanediol, 1,5-hexanediol, 2-methyl-1,8-octanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, , 3-butanediol, 2-ethyl-1,3-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3- Cyclohexane diol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and the like. These can be used individually by 1 type or in combination of 2 or more types.

Among these diol compounds, alkanediols having 4 to 8 carbon atoms are preferable in that the urethane (meth) acrylate obtained has a high elongation, that is, excellent balance between tensile strength at break and elongation until breakage. Among these, the cured product of urethane (meth) acrylate obtained has a low modulus, and since it is difficult to have a yield point in the tensile stress-strain curve diagram, 1,5-pentanediol, 1,6-hexanediol, 3-methyl- Polycarbonate diol using 1,5-pentanediol alone, polycarbonate diol using 1,5-pentanediol and 1,6-hexanediol, or 3-methyl-1,5-pentanediol and 1,6 -Polycarbonate diol combined with hexanediol or polycarbonate diol combined with 2-methyl-1,3-propanediol and 1,4-butanediol is preferred. In addition, polycarbonate diol using 3-methyl-1,5-pentanediol and 1,6-hexanediol together has a higher urethane (meth) acrylate cured product and higher elongation at break. Is particularly preferable because

The number average molecular weight of the component (a) polycarbonate diol is in the range of 300-1200. When a polycarbonate diol having a number average molecular weight of less than 300 is used, the resulting cured product of urethane (meth) acrylate has a high modulus, which tends to have a yield point in the tensile stress-strain curve diagram, which is not preferable. On the other hand, when a polycarbonate diol with a number average molecular weight exceeding 1200 is used, the resulting urethane (meth) acrylate cured product exhibits stickiness, and the cohesive strength decreases due to a decrease in the urethane bond concentration (the hydrogen bond concentration associated therewith). To do. As a result, the strength is reduced, and when the tensile stress is applied, the material is easily cut and the elongation is lowered. A particularly preferred range of the number average molecular weight of the polycarbonate diol is 400 to 600. A cured product of urethane (meth) acrylate using a polycarbonate diol having a number average molecular weight within the range is more excellent in scratch resistance.

<(B) Alicyclic diisocyanate>
The component (b) is an alicyclic diisocyanate, and a cured product of urethane (meth) acrylate synthesized using the alicyclic diisocyanate has excellent weather resistance and high elongation balance. Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, bis (4-isocyanatocyclohexyl) methane, 1,3-bisisocyanatomethylcyclohexane, 1,4-bisisocyanatomethylcyclohexane, norbornane diisocyanate, and the like. it can. These can be used individually by 1 type or in combination of 2 or more types.

<(C) Hydroxyl group-containing (meth) acrylic acid ester>
A component (c) is a component which provides radical reactivity by adding to the terminal of the urethane prepolymer obtained by making a component (a) and a component (b) react. The component (c) is not particularly limited as long as it is a hydroxy group-containing (meth) acrylic acid ester having at least one (meth) acryloyloxy group and at least one hydroxy group in the molecule. .

Specific examples of the component (c) include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4- Hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, adduct of 2-hydroxyethyl (meth) acrylate and caprolactone, 4- Examples include adducts of hydroxybutyl (meth) acrylate and caprolactone, trimethylolpropane diacrylate, pentaerythritol triacrylate, and dipentaerythritol pentaacrylate. These can be used individually by 1 type or in combination of 2 or more types.

<Urethane (meth) acrylate>
The urethane (meth) acrylate of the present invention is synthesized by reacting the above components (a), (b), and (c), and the synthesis method is not particularly limited, and various known synthesis methods. Is available. For example, the alicyclic diisocyanate of component (b) is dropped and reacted in a mixture of a polycarbonate diol of component (a) and a catalyst such as di-n-butyltin dilaurate at 50 to 90 ° C. It can be produced by obtaining a urethane prepolymer and reacting the hydroxyl group-containing (meth) acrylate of component (c) at 50 to 80 ° C. in the presence of a polymerization inhibitor such as hydroquinone monomethyl ether. Alternatively, the component (b) and the component (c) may be reacted first, and then the component (a) may be reacted.

Here, when the use ratio of the components (a), (b), and (c) is (a) / (b) / (c) = n / n + 1/2 (n is an integer of 2 or more) in terms of molar ratio, Since it can suppress that an unreacted surplus component arises and manufacturing cost can be reduced, it is preferable. Urethane (meth) acrylate is preferably reacted up to 98% or more at the end of the synthesis, and the reaction rate of the synthesis reaction can be calculated from various methods, for example, quantitative results of isocyanate amount according to JIS K 1556. .

  The number average molecular weight of the synthesized urethane (meth) acrylate is in the range of 5000 to 30000. A cured product of urethane (meth) acrylate having a number average molecular weight of less than 5000 has a high modulus, has a yield point in a tensile stress-strain curve diagram, has an elongation at break of less than 100%, and has insufficient elongation. Therefore, the scratch resistance is low. Moreover, since the elongation at break at 150 ° C. is small, the moldability is poor. On the other hand, when the number average molecular weight exceeds 30000, the viscosity of urethane (meth) acrylate becomes remarkably high, which hinders the operation of applying urethane (meth) acrylate when forming a cured product. In addition, since the cured product tends to be sticky, subsequent molding processing becomes difficult, and there are practical problems when used as a coating.

<Curable composition>
The curable composition of the present invention containing the urethane (meth) acrylate can be cured by irradiation with energy rays such as ultraviolet rays or electron beams, and the cured product has a tensile stress-strain measured at 23 ° C. The curve diagram has no yield point and the elongation at break is 100% or more.

Here, having no yield point is shown in FIG. 1, which is a tensile stress-strain curve diagram of Example 1 described later, for example, in a tensile stress (MPa) -strain (%) curve diagram measured at 23 ° C. Thus, it shows a curve in which the tensile stress continues to increase as the strain increases, and the cured product undergoes elastic deformation until it breaks, so the shape returns to its original state when the load is unloaded. On the other hand, having a yield point means, for example, a curve having a portion where the tensile stress is reduced despite an increase in strain, as shown in FIG. 2 which is a tensile stress-strain curve diagram of Comparative Example 2 described later. Since the deformation is elastic up to the yield point, the shape will return to its original value when the load is unloaded, but after the yield point it is a plastic deformation, so if a load exceeding the yield point is applied, the load will be removed. Even if it loads, it does not return to the original shape completely.

  The curable composition of the present invention preferably contains a silicon-based surface conditioner such as a silicon-based slip agent having a polymerizable unsaturated group and the leveling agent. In the case of using the silicon-based surface conditioner having a polymerizable unsaturated group, it is oriented and crosslinked in the surface layer at the time of curing, and the slip property can be maintained over a long period of time and the scratch resistance can be improved. The preferable compounding amount is 0.1 to 5% by weight.

This silicone-based surface conditioner having a polymerizable unsaturated group can be obtained by condensation reaction of both terminal carbinol-modified siloxane, one terminal diol siloxane, one terminal monool siloxane and (meth) acrylic acid, or polyisocyanate and hydroxyl. It can be obtained by an addition reaction using a group-containing (meth) acrylic acid ester. Specific examples thereof include, for example, X-22-164B (manufactured by Shin-Etsu Chemical Co., Ltd.), X-22-174DX (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-UV 3500 (manufactured by Big Chemie Japan), BYK-UV 3570 (Bic Chemie (Manufactured by Japan). These can be used individually by 1 type or in combination of 2 or more types.

In the curable composition of the present invention, other polymerization curable compounds can be blended within a range that does not impair the characteristics of the present invention. Specific examples thereof include polybasic acids such as phthalic acid, succinic acid, hexahydrophthalic acid, tetrahydrophthalic acid, terephthalic acid, azelaic acid and adipic acid, ethylene glycol, hexanediol, polyethylene glycol, polytetramethylene glycol and the like. Obtained by condensation reaction of polyester poly (meth) acrylate obtained by reaction with polyhydric alcohol and (meth) acrylic acid or its derivative, and bisphenols such as bisphenol A, bisphenol F, bisphenol S, tetrabromobisphenol A and epichlorohydrin. Bisphenol-type epoxy resin and (meth) acrylic acid or its derivatives reacted with epoxy (meth) acrylate, alkane diol, polyether diol, polyester diol, spirogly An organic diisocyanate compound is added to the hydroxyl group of an alcohol composed of one or a mixture of two or more alcohol compounds, and one or more (meth) acryloyloxy groups in the molecule and one Urethane (meth) acrylates other than those mentioned above, reacted with a hydroxy group-containing (meth) acrylic acid ester having a hydroxy group, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, di (meth) acryl Acid methylpentanediol, di (meth) acrylate diethylpentanediol, hydroxy Dipentyl glycol diphosphate (di (meth) acrylate), tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, tri (meth) acrylate tri Cyclodecane dimethanol, bis (2-acryloyloxyethyl) -2-hydroxyethyl isocyanurate, di (meth) acrylic acid cyclohexanedimethanol, di (meth) acrylic acid polyethoxylated cyclohexanedimethanol, di (meth) acrylic Acid polypropoxylated cyclohexanedimethanol, di (meth) acrylic acid polyethoxylated bisphenol A, di (meth) acrylic acid polypropoxylated bisphenol A, di (meth) acrylic acid hydrogenated bisphenol Nord A, di (meth) acrylic acid polyethoxylated hydrogenated bisphenol A, di (meth) acrylic acid polypropoxylated hydrogenated bisphenol A, bisphenoxyfluorene ethanol di (meth) acrylate, neopentyl glycol modified trimethylolpropane Di (meth) acrylate, ε-caprolactone adduct of neopentyl glycol hydroxypivalate (n + m = 2-5), di (meth) acrylate ester, γ-butyrolactone adduct of neopentyl glycol hydroxypivalate (n + m = 2) Di (meth) acrylic acid ester of 5 to 5), caprolactone adduct of neopentyl glycol (n + m = 2 to 5), di (meth) acrylic acid ester of di (meth) acrylate and caprolactone adduct of butylene glycol (n + m = 2 to 5) (Me ) Acrylic acid ester, di (meth) acrylic acid ester of caprolactone adduct of cyclohexanedimethanol (n + m = 2-5), di (meth) acrylic acid of caprolactone adduct of dicyclopentanediol (n + m = 2-5) Ester, Di (meth) acrylic acid ester of caprolactone adduct of bisphenol A (n + m = 2 to 5), Di (meth) acrylic acid ester of caprolactone adduct of hydrogenated bisphenol A (n + m = 2 to 5), Bisphenol F Di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trisethoxylated trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra of adduct of caprolactone (n + m = 2 to 5) (Meth) acrylic acid Steal, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, tris ( 2-acryloyloxyethyl) isocyanurate, dipentaerythritol penta (meth) acrylic ester, dipentaerythritol hexa (meth) acrylic ester, caprolactone modified dipentaerythritol penta (meth) acrylic ester, caprolactone modified dipentaerythritol hexa (Meth) acrylic acid ester, C2-C5 aliphatic hydrocarbon-modified trimethylolpropane triacrylate, C2-C5 aliphatic charcoal Hydrogen-modified dipentaerythritol penta (meth) acrylate, polyfunctional (meth) acrylic acid esters such as aliphatic hydrocarbon-modified dipentaerythritol tetra (meth) acrylate having 2 to 5 carbon atoms. These can be used alone or in combination of two or more.

The curable composition of this invention may contain an organic solvent as needed. Examples of the organic solvent include ester solvents such as butyl acetate and ethyl acetate, ketone solvents such as methyl ethyl ketone and acetone, and aromatic organic solvents such as toluene and xylene. These organic solvents can be used alone or in combination of two or more.

If necessary, a photopolymerization initiator can be added to the curable composition of the present invention. The type of the photopolymerization initiator is not particularly limited, and known ones can be used. Typical examples include benzophenone, 4,4-bis (diethylamino) benzophenone, 2,4,6-trimethylbenzophenone, Methyl orthobenzoyl benzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl Phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzyl-2- Methylamino-1- (4-morpholinophenyl) -butanone-1, diethylthioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4- Examples include trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and methylbenzoylformate. These may be used alone or in combination. Moreover, 0.1-10 weight% is preferable with respect to the sum total of a curable composition, and, as for the addition amount in the case of using a photoinitiator, 1-5 weight% is more preferable.

If necessary, the curable composition of the present invention is within a range that does not impair its performance, for example, a thermal polymerization initiator, a thermoplastic polymer, a slip agent, a leveling agent, an antifoaming agent, an antioxidant, Light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic fillers, organic fillers, colorants, flame retardants, antistatic agents, surface-organic-treated inorganic fillers, and other known additives May be used.

  When the curable composition of the present invention contains components other than the urethane (meth) acrylate obtained by reacting the components (a), (b) and (c), the urethane (meth) acrylate is used as a solvent. It is preferable to contain 50 to 100% by weight excluding the weight. When the content of urethane (meth) acrylate is less than 50% by weight, a yield point tends to occur in the tensile stress-strain curve diagram of the cured product, and the scratch resistance tends to decrease.

  The energy beam source for curing the curable composition of the present invention is not particularly limited. Examples include UV lamps, electron beam accelerators, γ-ray irradiation devices, high pressure mercury lamps, metal halide lamps, xenon lamps, and carbon arc lamps. Is mentioned.

  The curable composition of the present invention is excellent in scratch resistance and can form a cured product having properties such as stain resistance, chemical resistance and weather resistance, and is therefore suitable as a film for protecting various articles. Can be used. In addition, the cured product is excellent in molding processability and has high adhesion to the base material, so it is suitable for a sheet-like material used for vacuum forming, and is particularly molded with a resin such as an automobile interior panel. It is useful as a protective coating for members. Moreover, the curable composition of this invention can also form a film by not only shaping | molding after forming a cured | curing material but also hardening | curing after apply | coating a composition on a base material.

Hereinafter, the present invention will be described in detail with reference to examples.
[Example 1]
In a 2 L four-necked flask, 399.6 g of isophorone diisocyanate (IPDI), 334 g of methyl ethyl ketone (MEK), 0.36 g of di-n-butyltin dilaurate (DBTDL) and 0.53 g of hydroquinone monomethyl ether (MEHQ) were charged. It heated so that internal temperature might be set to 60 degreeC with a water bath, stirring. To this, 800 g of polycarbonate diol (manufactured by Daicel Chemical Industries, trade name: Plaxel CDCD205PL, number average molecular weight 500) synthesized from 3-methyl-1,5-pentanediol and 1,6-hexanediol as raw materials and methyl ethyl ketone (MEK) ) 200 g was charged into a dropping funnel and uniformly mixed, and the mixture was added dropwise at a constant rate for 3 hours while keeping the temperature inside the flask at 60 ° C., and stirred at the same temperature for 1 hour for reaction. Subsequently, 46.4 g of 2-hydroxyethyl acrylate (2-HEA) charged in another dropping funnel was dropped at a constant rate for 1 hour while maintaining the flask internal temperature at 60 ° C., and then the temperature of the flask contents was set to 70 ° C. The mixture was stirred for 2 hours until the reaction rate reached 98% or more to synthesize urethane acrylate UA1 (containing 30% methyl ethyl ketone). The number average molecular weight of this urethane acrylate UA1 was 7260. Here, the end point of the reaction was determined by the isocyanate concentration. Specifically, the reaction was terminated when the reaction rate calculated based on the amount of isocyanate quantified according to JIS K1556 reached 98% or more.

A curable composition consisting only of urethane acrylate UA1 was treated as described in the following measurement method and evaluation method to prepare a sample, and its characteristics were measured and evaluated. The synthetic material and number average molecular weight of urethane acrylate UA1 are shown in Table 1 below, and the test results are shown in Table 2 below. Moreover, the tensile stress-strain curve created based on the measurement of the film characteristic using the curable composition of Example 1 is shown in FIG. The cured product according to Example 1 does not have a yield point in the tensile stress-strain curve.

[Examples 2, 6, 8, Reference Examples 3-5 , 7 and Comparative Examples 1-6]
Urethane acrylates UA2-8 and HUA1-6 were synthesized in the same manner as in Example 1 except that the synthetic materials listed in Table 1 below were used. The number average molecular weight is as shown in Table 1. Moreover, the curable composition which consists only of each urethane acrylate UA2-8 and HUA1-6 was processed as described in the following measuring method and evaluation method, the sample was created, and the characteristic was measured and evaluated. The synthetic material and number average molecular weight of each urethane acrylate are shown in Table 1 below, and the test results are shown in Table 2 below. Moreover, the tensile stress-strain curve created based on the measurement of the film characteristic using the curable composition of the comparative example 2 is shown in FIG. The cured product according to Comparative Example 2 has a clear yield point in the tensile stress-strain curve.

Abbreviations in Table 1 are as follows.
CD205PL: Polycarbonate diol obtained from 3-methyl-1,5-pentanediol and 1,6-hexanediol as raw materials (trade name: Plaxel CDCD205PL, manufactured by Daicel Chemical Industries, Ltd.) Number average molecular weight 500
CD210PL: Polycarbonate diol obtained by using 3-methyl-1,5-pentanediol and 1,6-hexanediol as raw materials (manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel CDCD210PL) number average molecular weight 1000
T5650E: polycarbonate diol obtained from 1,5-pentanediol and 1,6-hexanediol as raw materials (trade name: DURANOL T5650E, manufactured by Asahi Kasei Chemicals Corporation) number average molecular weight 500
G3450J: Polycarbonate diol obtained from 2-methyl-1,3-propanediol and 1,4-butanediol as raw materials (trade name: DURANOL G3450J, manufactured by Asahi Kasei Chemicals Corporation) number average molecular weight 800
UH-50: Polycarbonate diol obtained from 1,6-hexanediol as a raw material (Ube Industries, Ltd., ETERNACOLL UH-50) number average molecular weight 500
CD220PL: Polycarbonate diol obtained by using 3-methyl-1,5-pentanediol, 1,6-hexanediol and carbonate as raw materials (trade name: Plaxel CDCD220PL, manufactured by Daicel Chemical Industries, Ltd.) number average molecular weight 2000
PTMG650: polytetramethylene diol, number average molecular weight 650
PTMG250: polytetramethylenediol, number average molecular weight 250
PCL500: polycaprolactone diol, number average molecular weight 500
IPDI: isophorone diisocyanate NBDI: norbornane diisocyanate H ₁₂ MDI: bis (4-isocyanatocyclohexyl) methane XDI: xylylene diisocyanate 2-HEA: 2-hydroxyethyl acrylate DBTDL: dilauric acid di-n-butyltin MEHQ: hydroquinone monomethyl ether MEK: Methyl ethyl ketone

[Measurement method and evaluation method]
<Number average molecular weight>
The number average molecular weight is a value obtained by measuring polycarbonate diol or urethane (meth) acrylate using gel permeation chromatography (HLC-8120GPC manufactured by Tosoh Corporation) and converting the measurement result to polystyrene.

<Film characteristic value>
Each curable composition was applied to glass so that the dry film thickness was 100 μm, heated at 60 ° C. for 30 minutes to volatilize the solvent, and then in an atmosphere of nitrogen, an electron beam accelerator (Electronics manufactured by Iwasaki Electric Co., Ltd.) Curtain EC250 / 15 / 180L) An evaluation film was prepared by irradiating and curing a 5 Mrad electron beam at 175 Kv. This film was peeled from glass and cut into a strip shape having a width of 25 mm and a length of 90 mm as a sample, and it was 23 ° C. and a tensile speed of 30 mm / min using a universal material testing machine (Autograph AG-IS manufactured by Shimadzu Corporation). A tensile stress-strain curve is created from the results obtained by applying a load at, and the tensile stress-strain curve with no yield point is marked with ◯ and the tensile stress-strain curve with x, and the elongation of the sample when the sample breaks Was the elongation at break.

<Molding processability>
Each curable composition was applied to an acrylic film (film thickness 75 μm) having a 1 μm acrylic urethane primer layer so that the dry film thickness was 10 μm, heated at 60 ° C. for 30 minutes to volatilize the solvent, and then a nitrogen atmosphere A sample was prepared by irradiating a 5 Mrad electron beam at 175 Kv with an electron beam accelerator (Electrocurtain EC250 / 15/180 L, manufactured by Iwasaki Electric Co., Ltd.). A sample cut into a strip shape having a width of 25 mm and a length of 90 mm was used as a specimen, and a load was applied at 150 ° C. and a tensile speed of 1000 mm / min with a universal material testing machine (Tensilon manufactured by Toyo Baldwin). If the elongation at break of the test specimen was 100% or more, it was rated as ◯, and if it was less than that, it was marked as x.

<Appearance and surface condition>
Using the sample prepared in the above-described molding processability test, the appearance and surface condition were evaluated visually and by touch. If there was no abnormality, it was rated as ○, and if there was a tack, it was marked as ×.

<Adhesion>
Each curable composition was applied to an acrylic film (film thickness 75 μm) having a 1 μm acrylic urethane primer layer so that the dry film thickness was 10 μm, heated at 60 ° C. for 30 minutes to volatilize the solvent, and then a nitrogen atmosphere Inside, a sample was prepared by irradiating a 5 Mrad electron beam at 175 Kv with an electron beam accelerator (electrocurtain EC250 / 15/180 L, manufactured by Iwasaki Electric Co., Ltd.), in a 1 mm square grid cellophane tape peeling test in accordance with JIS K5400 evaluated. The case where there was no cell peeling was marked with ◯, and the case where even one cell was peeled off was marked with ×.

<Abrasion resistance>
Each curable composition was applied to a polyester film (film thickness 100 μm) so that the dry film thickness was 10 μm, heated at 60 ° C. for 30 minutes to volatilize the solvent, and then in a nitrogen atmosphere, an electron beam accelerator ( A sample was prepared by irradiating a 5 Mrad electron beam at 175 Kv (electro curtain EC250 / 15/180 L) manufactured by Iwasaki Electric Co., Ltd. The surface of this sample was rubbed 10 times with a 300 μm diameter brass brush (overall weight 100 g) with only its own weight applied. Observed later, the case where no scratch was observed was marked with ◯, and the case where scratch was seen was marked with ×.

<Contamination resistance>
Specimens were prepared by the same method as the scratch resistance test, and oil-based black ink (made by Teranishi Chemical Industry Co., Ltd.), water-based blue ink, and water-based red ink (all manufactured by Pilot Corporation) shown in Table 2 on the surface. After coating and holding at room temperature for 24 hours, the ink was wiped off with absorbent cotton and visually observed. If there was no change on the surface, it was rated as ◯.

<Chemical resistance>
A specimen was prepared by the same method as the scratch resistance test, and ethanol, 10% hydrochloric acid (HCl water), and 10% aqueous sodium hydroxide solution (NaOH water) shown in Table 2 were applied to the surface. After holding for a period of time, the chemical was wiped off with absorbent cotton and visually observed. If there was no change on the surface, it was rated as ◯.

<Weather resistance>
Each curable composition was applied to an acrylic film (film thickness 75 μm) so as to have a dry film thickness of 10 μm, heated at 60 ° C. for 30 minutes to volatilize the solvent, and then an electron beam accelerator ( A sample was prepared by irradiating a 5 Mrad electron beam at 175 Kv (electro curtain EC250 / 15/180 L) manufactured by Iwasaki Electric Co., Ltd., and weather resistance was evaluated using a metal halide lamp type eye super UV tester (SUV-W131 manufactured by Iwasaki Electric Co., Ltd.). As a result, when there was no change in 100 hours, the case where there was a change such as ◯, discoloration, cracking, glossiness, etc. was marked with ×.

The cured products of the curable compositions of Examples 1, 2, 6, and 8 and Reference Examples 3 to 5 , and 7 have no yield point in the tensile stress-strain curve, and the elongation at break is 100% or more. In addition to being excellent in scratch resistance and molding processability, it was also excellent in stain resistance, weather resistance, adhesion and the like.
In the curable composition of Comparative Example 1, the number average molecular weight of the polycarbonate diol as the component (a) is large, so the elongation at break of the cured product is small and the moldability is poor. Moreover, the surface state of hardened | cured material is also bad.
Since the curable composition of Comparative Example 2 has a small number average molecular weight of urethane (meth) acrylate, the cured product has a yield point in the tensile stress-strain curve, and the elongation at break is also small. Therefore, the moldability of the cured product is poor and the scratch resistance is low.
Since the curable composition of Comparative Example 3 uses polytetramethylene diol as the component (a), the cured product has low adhesion, stain resistance, weather resistance, and the like.
Since the curable composition of Comparative Example 4 uses polycaprolactone diol as the component (a), the stain resistance is low.
Since the curable composition of Comparative Example 5 uses not a cycloaliphatic diisocyanate but an xylylene diisocyanate which is an aromatic diisocyanate as the component (b), the adhesiveness, stain resistance, weather resistance, etc. of the cured product Is bad.
Since the curable composition of Comparative Example 6 uses polytetramethylene diol as the component (a), the cured product has low adhesion, stain resistance, weather resistance, and the like. Moreover, since the molecular weight of polytetramethylene diol is small, the cured product has a yield point and poor scratch resistance.

[Examples 9 to 11] and [Comparative Example 7]
The weights shown in Table 3 for the urethane acrylates UA1, HUA1 and HUA2 prepared in Example 1 and Comparative Examples 1 and 2, pentaerythritol tetraacrylate (PETA, crosslinking agent), and BYK-UV3570 (surface conditioner) The curable composition mixed at a ratio was processed as described in the above measurement method and evaluation method to prepare a sample, and its characteristics were measured and evaluated. The test results are shown in Table 3 below.
Abbreviations in Table 3 are as follows.
PETA: Pentaerythritol tetraacrylate BYK-UV3570: PO-modified-2-neopentylglycol diacrylate solution of polydimethylsiloxane having a polyester-modified acrylic group (manufactured by BYK Japan)

The cured products of the curable compositions of Examples 9 to 11 do not have a yield point in the tensile stress-strain curve and have an elongation at break of 100% or more, and thus have excellent scratch resistance and molding processability. Excellent contamination resistance, weather resistance and adhesion.
Since the curable composition of Comparative Example 7 contains only 45% of urethane acrylate UA1 by weight excluding the solvent, the cured product has a yield point and has low scratch resistance.

Claims (4)

A urethane (meth) acrylate having a number average molecular weight of 5000 to 30000 obtained by reacting the following (a), (b) and (c) :
Urethane (meth) acrylate that provides a cured product having a yield point and an elongation at break of 100% or more in a tensile stress-strain curve diagram measured at 23 ° C.
(A) Polycarbonate diol having a number average molecular weight of 400 to 600 (b) Isophorone diisocyanate (c) 2-hydroxyethyl acrylate The urethane (meth) acrylate according to claim 1, wherein the polycarbonate diol is synthesized from 3-methyl-1,5-pentanediol and 1,6-hexanediol .   A curable composition comprising the urethane (meth) acrylate according to claim 1 or 2, and a solvent,
  A curable composition capable of obtaining a cured product having a yield point and an elongation at break of 100% or more in a tensile stress-strain curve diagram measured at 23 ° C. The curable composition according to claim 3 , comprising 50 to 100% by weight of the urethane (meth) acrylate, excluding the solvent.

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