JP6766456B2 - Radical curable compositions, plastic sheets, plastic sheet rolls and moldings - Google Patents

Description

The present invention relates to a radical curable composition for forming a plastic sheet. More specifically, the present invention makes it easy to form a sheet roll formed by winding a plastic sheet, and further, optical properties and a surface of a molded product to be a final cured product. The present invention relates to a radical curable composition for forming a plastic sheet that provides a molded product having excellent hardness and impact resistance.

Conventionally, as a substrate for a display, a substrate made of glass has been often used. For example, a chemically strengthened glass substrate having a thickness of about 0.5 to 2 mm is widely used as a protective plate. Further, as a touch panel substrate, a glass substrate having a thickness of about 0.2 to 1.1 mm is widely used. Further, in liquid crystal displays and organic electroluminescence (organic EL) displays, glass substrates having a thickness of about 0.2 to 0.7 mm are widely used.

On the other hand, in recent years, plastic substrates have begun to be used from the viewpoint of weight reduction and safety, and also for the purpose of manufacturing flexible displays. In practice, polymethylmethacrylate (PMMA), polycarbonate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a substrate obtained by applying a hard coat to these resin sheets is used. Such plastic substrates have not only optical performance such as light transmittance and birefringence, but also thermal characteristics such as heat resistance and coefficient of linear expansion, mechanical characteristics such as surface hardness and flexural modulus, water absorption and specific gravity, and resistance. High processing suitability such as chemical and solvent resistance is required.

In order to satisfy these various properties, a large number of resins have been proposed regardless of thermoplasticity or thermosetting property. In particular, a substrate in which a sheet made of these resins is hard-coated to improve the surface hardness has been proposed, but the surface hardness exceeding that of glass has not been obtained at present.

Further, in recent years, there are some molded articles obtained by photocuring a specific photopolymerizable composition. For example, it is disclosed that a photopolymerizable composition composed of a polyfunctional urethane (meth) acrylate having an alicyclic structure and a polyfunctional (meth) acrylate having an alicyclic structure gives a resin molded body having high pencil hardness. (See, for example, Patent Document 1.) Also, from a monofunctional (meth) acrylate having an alicyclic structure, a polyfunctional urethane (meth) acrylate having an alicyclic structure, and a polyfunctional (meth) acrylate having an alicyclic structure. It is disclosed that the photopolymerizable composition obtained by the above gives a resin molded product having excellent optical properties and thermomechanical properties (see, for example, Patent Document 2).

However, although the disclosed techniques of Patent Documents 1 and 2 have obtained plastic sheets having high surface hardness, these are plastics obtained by casting a photocurable composition between two glass plates by a batch method. It manufactures sheets and obtains flat plastic sheets. Therefore, the obtained plastic sheet cannot be further three-dimensionally molded. Such "three-dimensional molding" is three-dimensional because molding is performed in a direction other than a flat surface, for example, a substantially vertical direction, whereas a conventional plastic sheet can only obtain a flat molded product. It means a molding method for obtaining a molded product.

Further, in recent years, there has been an increasing demand for three-dimensional molding of plastic sheets from the viewpoint of weight reduction and designability.
Also, in the production of plastic sheets, a method of continuously manufacturing instead of a batch method is being studied. For example, it is conceivable to apply a photocurable composition on a support film and irradiate it with active energy rays, but when the photocurable composition as described above is used, the photocurable composition is used. Since the viscosity of the resin is low, the coatability is poor, and a good plastic sheet, particularly a thick-film plastic sheet, cannot be obtained. Furthermore, even if the above photocurable composition is simply applied and irradiated with active energy rays, the cured plastic sheet is not flexible enough to be stored in a roll state, and , It is not something that can be three-dimensionally molded.

For example, Patent Document 3 describes a plastic that does not crack or crack when the plastic sheet is continuously manufactured, when it is wound on a roll, when it is conveyed between rolls, or when the support sheet is peeled off. For the purpose of providing a sheet, a method is described in which the flexural modulus of a predetermined region at both ends is lower than the flexural modulus of a predetermined region at a central portion in the width direction of the plastic sheet.

JP-A-2006-193596 JP-A-2007-204736 JP-A-2009-127019

However, in the technique of Patent Document 3, curing of only the end portion of the plastic sheet is taken into consideration, and it is difficult to obtain a sheet that is optically and mechanically uniform. Further, the reaction rate of at least a part of the plastic sheet exceeds 80%, and it is difficult to perform the subsequent three-dimensional molding process using such a plastic sheet.

Therefore, in the present invention, under such a background, a plastic sheet roll formed by winding a plastic sheet is easily formed, and further, optical characteristics, surface hardness, and impact resistance of a three-dimensional molded product to be a final cured product are formed. It is an object of the present invention to provide a radical curable composition for forming a plastic sheet for obtaining an excellent molded product. Further, it is an object of the present invention to provide a plastic sheet, a plastic sheet roll, and a three-dimensional molded product by using such a radical curable composition.

However, as a result of diligent studies by the present inventors to solve the above problems, it contains a polyfunctional urethane (meth) acrylate having an alicyclic structure, a polyfunctional (meth) acrylate having an alicyclic structure, and a polymerization initiator. To increase the viscosity of the radical curable composition by further adding a (meth) acrylic resin having an alicyclic structure having a medium molecular weight, which is not too high in molecular weight, to the radical curable composition. Therefore, it becomes easy to continuously form a plastic sheet roll formed by winding a plastic sheet obtained by curing, and a thicker film can be formed. In addition, a three-dimensional molded product to be a final cured product can be obtained. The present invention has been completed by finding that it has excellent effects on optical properties, surface hardness, and impact resistance.

That is, the gist of the present invention is the following <1> to < 7 >.
<1> The following components (A), (B), (C) , (D) and (E) are contained, and the content ratio of each component (A) to (E) is the following [i] to [iv]. A radical curable composition characterized by being satisfied .
(A) Polyfunctional urethane (meth) acrylate having an alicyclic structure (B) Polyfunctional (meth) acrylate having an alicyclic structure (however, the component (A) is excluded)
(C) (Meta) acrylic resin having an alicyclic structure having a weight average molecular weight of 50,000 to 700,000 (D) Polymerization initiator
(E) Mercapto group-containing compound
[I] The blending ratio of the component (A) and the component (B) is (A) :( B) = 10: 90 to 50:50 (weight ratio).
[Ii] The content of the component (C) is 1 to 30 parts by weight with respect to a total of 100 parts by weight of the component (A) and the component (B).
[Iii] The content of the component (D) is 0.1 to 5 parts by weight based on 100 parts by weight of the total of the component (A) and the component (B).
[Iv] The content of the component (E) is 10 parts by weight or less with respect to a total of 100 parts by weight of the component (A) and the component (B).
<2> has a pre Kiaburawa structure (meth) acrylic resin (C), wherein <1> Symbol mounting, which is a homopolymer of things having an alicyclic structure-containing (meth) acrylate (c1) Radical curable composition .
<3 > The radical curable composition according to <1> or <2>, wherein the viscosity at 23 ° C. is 100 to 20,000 mPa · s.

< 4 > A plastic sheet obtained by curing the radical curable composition according to any one of <1> to < 3 >, wherein the reaction rate of the (meth) acryloyl group is 50% or more and less than 75%. A plastic sheet that features that.
< 5 > The plastic sheet according to < 4 >, wherein the thickness is 50 to 10,000 μm.
< 6 > A plastic sheet roll according to the above < 4 > or < 5 >, wherein the plastic sheet is wound.
< 7 > A molded product obtained by molding the plastic sheet according to < 4 > or < 5 > or a plastic sheet unwound from the plastic sheet roll according to < 6 >, which is a reaction of a (meth) acryloyl group. A molded product having a rate of 75% or more.

The radical curable composition of the present invention can form a plastic sheet having a desired thickness by containing the components (A) to ( E ) in a specific ratio , and is a wound plastic sheet. A roll can be easily formed, and a molded product having excellent optical properties, surface hardness, and impact resistance can be obtained as a final cured product. Further, by adjusting the content of the component (C), the viscosity of the radical curable composition can be increased, and the impact resistance of the molded product to be the final cured product can be adjusted.

It is a figure explaining the falling ball test performed in this invention.

The present invention will be described in detail below.
In the present invention, "(meth) acrylate" is a general term for acrylate and methacrylate, and "(meth) acrylic" is a general term for acrylic and methacrylic. Further, the term "polyfunctional" as used herein means having two or more (meth) acryloyl groups in the molecule.

<Explanation of radical curable composition>
The radical curable composition of the present invention contains the following components (A), (B), (C) , (D) and (E) .
(A) Polyfunctional urethane (meth) acrylate having an alicyclic structure (B) Polyfunctional (meth) acrylate having an alicyclic structure (however, the component (A) is excluded)
(C) A (meth) acrylic resin (D) polymerization initiator having an alicyclic structure having a weight average molecular weight of 50,000 to 700,000.
(E) Mercapto group-containing compound

(Polyfunctional urethane (meth) acrylate having an alicyclic structure: component (A))
The component (A) is a urethane (meth) acrylate containing two or more (meth) acryloyl groups in the molecule. Since it is polyfunctional, the curing rate is improved and a plastic sheet can be obtained with high productivity. Further, a crosslinked resin can be formed by a radical polymerization reaction by heat or light to obtain a plastic sheet having high surface hardness. Further, since the component (A) has a urethane group in the molecule, a flexible plastic sheet having excellent mechanical strength such as flexural modulus and impact resistance can be obtained by hydrogen bonding. The improvement in surface hardness is particularly exhibited by a tetrafunctional or higher functional urethane (meth) acrylate. Further, the polyfunctional urethane (meth) acrylate (A) has an alicyclic structure in the molecule, and this alicyclic structure reduces the water absorption rate of the plastic sheet.

The number average molecular weight of the component (A) is preferably 200 to 5,000. It is more preferably 400 to 3,000, still more preferably 500 to 1,000. If the number average molecular weight is too small, the curing shrinkage tends to increase and birefringence tends to occur. On the contrary, if it is too large, the crosslinkability tends to decrease and the heat resistance tends to decrease.

As the polyfunctional urethane (meth) acrylate having an alicyclic structure as the component (A), a polyisocyanate compound having an alicyclic structure and a hydroxyl group-containing (meth) acrylate are used, if necessary, using a catalyst such as dibutyltin dilaurate. It can be obtained by reacting with.

Specific examples of the polyisocyanate compound having an alicyclic structure include isophorone diisocyanate, norbornene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, and hydrogenated xyl. Examples thereof include range isocyanates, hydrogenated diphenylmethane diisocyanates, and trimeric compounds of isophorone diisocyanates. Of these, isophorone diisocyanate is preferable because it has good light resistance.

Specific examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3- (meth). Examples thereof include acryloyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol tri (meth) acrylate. Of these, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol tri (meth) acrylate are preferable in terms of surface hardness. Particularly preferred is pentaerythritol tri (meth) acrylate.

Two or more kinds of polyfunctional urethane (meth) acrylate (A) having an alicyclic structure obtained by reacting a polyisocyanate compound having an alicyclic structure with a hydroxyl group-containing (meth) acrylate can be used in a radical curable composition. It may be mixed and used. Among these reactants, acrylate is preferable from the viewpoint of curing rate, tetrafunctional or higher is more preferable from the viewpoint of heat resistance, and the alicyclic structure represented by the following formulas (1) to (4) is more preferable from the viewpoint of surface hardness. A tetrafunctional or higher functional urethane (meth) acrylate having a above is particularly preferable.

In formula (3), R ₁ is independently a hydrogen or methyl group.

(Polyfunctional (meth) acrylate having an alicyclic structure: component (B))
Since the component (B) is also a polyfunctional (meth) acrylate, it gives a highly heat-resistant plastic sheet. The effect of improving heat resistance is greater than that of the urethane (meth) acrylate of the component (A), but this monomer alone becomes brittle because it becomes a glass-like crosslinked resin. Therefore, it is preferable that the urethane (meth) acrylate of the component (A) and the polyfunctional (meth) acrylate of the component (B) are blended in a specific ratio and copolymerized. As a result, a plastic sheet having good surface hardness, heat resistance, and flexibility can be obtained. If the number of functional groups of the component (B) is excessively large, the balance between heat resistance and flexibility tends to be lost. Therefore, the component (B) is preferably bifunctional and more preferably methacrylate. .. In addition, the component (B) also has an alicyclic structure, and this alicyclic structure also reduces the saturated water absorption rate of the plastic sheet.

Examples of the polyfunctional (meth) acrylate having the alicyclic structure of the component (B) (excluding the component (A)) include bis (hydroxy) tricyclo [5.2.1.0 ^2,6 ] decan. = Di (meth) acrylate, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] Decane = di (meth) acrylate, bis (hydroxy) tricyclo [5.2.1.0 ^2,6 ] Decane = acrylate methacrylate, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] Decane = acrylate methacrylate, bis (hydroxy) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . ^09,13 ] Pentadecane = di (meth) acrylate, bis (hydroxymethyl) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . ^09,13 ] Pentadecane = di (meth) acrylate, bis (hydroxy) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . ^09,13 ] Pentadecane = acrylate methacrylate, bis (hydroxymethyl) pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . ^09,13 ] Pentadecane = acrylate methacrylate, 2,2-bis [4- (β-methacryloyloxyethoxy) cyclohexyl] propane, 1,3-bis (methacryloyloxymethyl) cyclohexane, 1,3-bis (methacryloyloxyethyl) Bifunctional (meth) acrylates such as oxymethyl) cyclohexane, 1,4-bis (methacryloyloxymethyl) cyclohexane, 1,4-bis (methacryloyloxyethyloxymethyl) cyclohexane, 1,3,5-tris (methacryloyloxymethyl) ) Trifunctional (meth) acrylates such as cyclohexane and 1,3,5-tris (methacryloyloxyethyloxymethyl) cyclohexane are mentioned. Among these, bifunctional (meth) acrylates are preferable from the viewpoint of flexibility and have heat resistance. From this point of view, bifunctional methacrylate is more preferable. Further, from the viewpoint of optical performance, at least one or more bifunctional (meth) acrylates selected from the group consisting of the following general formulas (5), (6) and (7) are preferable, and bifunctional methacrylate is particularly preferable.

In formula (5), R ₂ is an alkylene group which may independently contain an ether bond having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, R ₃ is an independent hydrogen or methyl group, and a is an independent hydrogen or methyl group. 1 or 2, b is 0 or 1.

In the formula (6), R ₄ is an alkylene group which may independently contain an ether bond having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, and R ₅ is an independent hydrogen or methyl group.

In formula (7), R ₆ is an independently hydrogen or methyl group, and R ₇ is an alkylene group which may independently contain an ether bond having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, R ₈ Are independently hydrogen or methyl groups.

The mixing ratio of the components (A) and component (B), (A) :( B) = 10: 90~50: 50 ( weight ratio) Ru der. If the amount of the component (A) is too small, the surface hardness tends to decrease, and conversely, if the amount of the component (B) is too small, the solubility tends to decrease. The preferred range of the blending ratio is 15:85 to 45:55 (weight ratio), and more preferably 20:80 to 40:60 (weight ratio).

(A (meth) acrylic resin having an alicyclic structure having a weight average molecular weight of 50,000 to 700,000: component (C))
The (meth) acrylic resin having the alicyclic structure of the component (C) is effective for increasing the viscosity of the radical curable composition, for example, poly (isobornyl (meth) acrylate), poly (adamantyl (meth)). ) Acrylate), poly (norbornen (meth) acrylate), poly (dicyclopentanyl (meth) acrylate) and other mono (meth) acrylate (c1) homopolymers having an alicyclic structure, and poly (dicyclopentanyl). Condensation composition of methanol and (meth) acrylate), etc., among which homopolymers of mono (meth) acrylate (c1) having an alicyclic structure in terms of compatibility are preferable, and poly (dicyclopentanyl) is particularly preferable. (Meta) acrylate), poly (adamantyl (meth) acrylate) and the like are preferable.

It is important that the weight average molecular weight of the (meth) acrylic resin (C) having an alicyclic structure is 50,000 to 700,000, particularly preferably 100,000 to 700,000, and further preferably 300,000 to 650,000. Is. If the weight average molecular weight is too small, the viscosity is increased for continuous coating, so that a large amount of the (meth) acrylic resin (C) is required, for example, 30% by weight or more, and therefore impact resistance is improved. It tends to decrease, and if it is too large, the solubility tends to be poor and the productivity tends to decrease.
The above weight average molecular weight means a standard polystyrene-equivalent weight average molecular weight (Mw) measured by GPC (gel permeation chromatography).

The (meth) acrylic resin (C) can be produced by a polymerization method by irradiation with active energy rays in addition to the solution polymerization method, but the polymerization method by ultraviolet irradiation is particularly preferable from the viewpoint of controlling the molecular weight.

The content of the (meth) acrylic resin (C) having an alicyclic structure is 1 to 1 to 100 parts by weight in total of the component (A) and the component (B) in terms of thick film forming property due to high viscosity. a 30 parts by weight, in particular 2 to 18 parts by weight, more preferably 2 to 15 parts by weight, especially 3 to 12 parts by weight. If the content is too small, the viscosity tends to be insufficient and it tends to be difficult to thicken the film, and if it is too large, the viscosity tends to be too high and the productivity tends to decrease.

(Polymerization initiator: component (D))
The radical curable composition of the present invention contains a polymerization initiator (D). Examples of such a polymerization initiator include a photopolymerization initiator (Dl) and a thermal polymerization initiator (Dh). In particular, in the present invention, it is preferable to contain a photopolymerization initiator (Dl) because it is preferable to cure by light from the viewpoint that the curing reaction proceeds efficiently and the productivity is good.

Examples of the photopolymerization initiator (Dl) include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, and 2,4,6-trimethyl. Examples thereof include benzoyldiphenylphosphine oxide. Among these, radical cleavage type photopolymerization initiators such as 1-hydroxycyclohexylphenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are preferable. These photopolymerization initiators (Dl) may be used alone or in combination of two or more.

A known compound can be used as the thermal polymerization initiator (Dh). For example, hydroperoxides such as hydroperoxide, t-butylhydroperoxide, diisopropylbenzenehydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, di-t-butyl peroxide, dicumyl peroxide, etc. Dialkyl peroxides such as, t-butyl peroxybenzoate, peroxy esters such as t-butyl peroxy (2-ethylhexanoate), diacyl peroxides such as benzoyl peroxide, peroxy carbonates such as diisopropyl peroxy carbonate. , Peroxyketal, ketone peroxide and other peroxides. These thermal polymerization initiators (Dh) may be used alone or in combination of two or more.
These photopolymerization initiators (Dl) and thermal polymerization initiators (Dh) can also be used in combination.

The content of the polymerization initiator (D) is 0.1 to 5 parts by weight based on 100 parts by weight of the total of the component (A) and the component (B), and further 0.2 to 4 parts by weight, particularly 0.2 to 4 parts by weight. It is preferably 0.3 to 3 parts by weight. If the content is too high, the retardation of the plastic sheet tends to increase and the light transmittance at 400 nm tends to decrease. On the other hand, if the amount is too small, the polymerization rate may decrease and the polymerization may not proceed sufficiently.

(Mercapto group-containing compound: component (E))
Furthermore, in the present invention, those containing a mercapto group-containing compound (E) in terms of increasing the crosslink density. Examples of the mercapto group-containing compound (E) include pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, pentaerythol-tetrakis (3-sulfanylbutanoate), 1,3,5. -Tris (2- (3-sulfanylbutanoyloxy) ethyl) and the like can be mentioned.

Further, for the purpose of improving the storage stability of the radical curable composition, it is preferable to use a mercapto group-containing compound (E1) having a secondary mercapto group. Examples of the mercapto group-containing compound (E1) include bifunctional thiols such as 1,4-bis (3-mercaptobutylyloxy) butane and 1,3,5-tris (2- (3-sulfanylbutanoyloxy). ) Ethyl), Tris-[(3-mercaptopropionyloxy) -ethyl-]-isocyanurate, trimethylolpropane tris (3-mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate), tri Examples thereof include trifunctional thiols such as trimethylolpropane tris (3-mercaptobutyrate) and trimethylolethanetris (3-mercaptobutyrate), and tetrafunctional thiols such as pentaerythritol tetrakis (3-sulfanylbutanoate).

The number of mercapto groups contained in one molecule of such a compound is usually 2 to 6 from the viewpoint of curability of the radical curable composition, preferably 2 to 4. Moreover, it is preferable that all the contained mercapto groups are mercapto group-containing compounds which are secondary mercapto groups.
The molecular weight of the mercapto group-containing compound (E) is usually 250 to 800, preferably 300 to 600. If the molecular weight is too small, the viscosity of the radical curable composition tends to be low, and if it is too large, the viscosity of the radical curable composition tends to be high.

These mercapto group-containing compounds (E) are used in a proportion of 10 parts by weight or less with respect to a total of 100 parts by weight of the component (A) and the component (B) , and further 5 parts by weight or less, particularly 4 It is preferably parts by weight or less. If the amount used is too large, the heat resistance and rigidity of the obtained plastic sheet or molded product tend to decrease.

In the present invention, the curable composition may contain a small amount of auxiliary components as long as the physical properties of the plastic sheet or molded product of the present invention are not impaired. For example, a monomer having an ethylenically unsaturated bond other than the component (A) and the component (B), a polymerization inhibitor, an antioxidant, an ultraviolet absorber, an antifoaming agent, a leveling agent, a bluing agent, and a dyeing agent. Pigments, fillers, etc. When the curing by active energy ray irradiation and the curing by heating are used in combination, it is preferable to use a photopolymerization initiator (Dl) and a thermal polymerization initiator (Dh) in combination.

Examples of the monomer having an ethylenically unsaturated bond other than the component (A) and the component (B) include methyl methacrylate, 2-hydroxyethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, and cyclohexyl (meth). Alicyclic structure such as meta) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, norbornene (meth) acrylate, dicyclopentanyl (meth) acrylate, condensed composition of dicyclopentanyl methanol and (meth) acrylate, etc. Monofunctional (meth) acrylate such as mono (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, di (meth) acrylate of polyethylene glycol of tetraethylene glycol or higher. Meta) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2-hydroxy 1,3-di (meth) acryloxy Polyfunctional (meth) acrylates such as propane, 2,2-bis [4- (meth) acryloyloxyphenyl] propane, trimethylpropantri (meth) acrylate, acrylamide, methacrylicamide, acrylonitrile, methacrylonitrile and the like (meth) ) Acrylate derivatives, styrene compounds such as styrene, chlorostyrene, divinylbenzene, α-methylstyrene and the like can be mentioned.

The content of the monomer having an ethylenically unsaturated bond other than the component (A) and the component (B) is 30 parts by weight or less based on 100 parts by weight of the total of the component (A) and the component (B). Is preferably 20 parts by weight or less, particularly preferably 10 parts by weight or less. If the content is too high, the heat resistance of the plastic sheet or molded product tends to decrease.

Examples of the antioxidant include 2,6-di-t-butylphenol, 2,6-di-t-butyl-p-cresol, 2,4,6-tri-t-butylphenol, and 2,6-di-. t-Butyl-4-s-butylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, n-octadecyl-β- (4'-hydroxy-3', 5'-di-t-butylphenyl ) Propionate, 2,6-di-t-butyl-4- (N, N-dimethylaminomethyl) phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 2,4 -Bis (n-octylthio) -6- (4-hydroxy-3', 5'-di-t-butylanilino) -1,3,5-triazine, 4,4-methylene-bis (2,6-di-) t-Butylphenol), 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], bis (3,5-di-t-butyl-4-hydroxybenzyl) ) Gulp, 4,4'-di-thiobis (2,6-di-t-butylphenol), 4,4'-tri-thiobis (2,6-di-t-butylphenol), 2,2-thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N'-hexamethylenebis- (3,5-di-t-butyl-4-hydroxyhydroxyhydrocinnamide, N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, calcium (3,5-di-t-butyl-4-hydroxybenzyl) monoethylphosphophos Nate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-t-butyl-4-hydroxyphenyl) ) Isocyanurate, Tris (3,5-di-t-butyl-4-hydroxybenzyl) Isocyanurate, 1,3,5-Tris-2 [3 (3,5-di-t-butyl-4-hydroxyphenyl) Propionyloxy] ethyl isocyanate, tetrakis [methylene-3- (3', 5'-di-t-butyl-4-hydroxyphenyl) propionate] methane, 3,5-di-t-butyl-4-hydroxybenzylphosphite -Compounds such as diethyl ester can be mentioned, and these compounds may be used alone or in combination of two or more. Among these, tetrakis [me]. Tylene-3- (3', 5'-di-t-butyl-4-hydroxyphenyl) propionate] methane is particularly preferable because it has a greater effect of suppressing hue.

The content ratio of the antioxidant is usually preferably 0.001 to 1 part by weight, particularly preferably 0.01 to 0.5, based on 100 parts by weight of the total of the component (A) and the component (B). It is a part by weight. If the amount of the antioxidant is too small, the light resistance of the plastic sheet tends to decrease, and if it is too large, the light transmittance tends to decrease.

The radical curable composition of the present invention can be produced by the same method as known. For example, it is produced by blending components (A), (B), (C) , (D) and (E), and if necessary, auxiliary components, and stirring and mixing them at a temperature of 20 to 50 ° C. until uniform. be able to.
Thus, the radical curable composition of the present invention is obtained.

The radical curable composition of the present invention preferably has a viscosity at 23 ° C. of 100 to 20,000 mPa · s, more preferably 400 to 10,000 mPa · s, still more preferably 800 to 6,000 mPa · s. is there. If the viscosity is too low, the thick film forming property tends to decrease, and conversely, if the viscosity is too high, the productivity tends to decrease. Examples of the method for adjusting the viscosity include appropriately controlling the types and blending amounts of the components (A), (B) and (C). The composition viscosity at this time is a value measured using a cone-plate type viscometer (TPE-100 manufactured by Toki Sangyo) at a Peltier plate temperature of 23 ° C and a cone rotor used: 3 ° × R14. is there.

<Manufacturing method of plastic sheet [I] and molded product [II]>
Next, a method for producing the plastic sheet [I] of the present invention using such a radical curable composition, and further, a molded product [II] obtained by molding the plastic sheet [I] will be described.

The plastic sheet [I] of the present invention is obtained by curing the radical curable composition by heating or irradiation with active energy rays so that the reaction rate is usually 50% or more and less than 75%.

For such a plastic sheet [I], a mold in which two transparent glasses are opposed to each other is formed through a commonly used batch type photoforming method, that is, a spacer for thickness control, and the cavity is filled with the plastic sheet [I]. It can also be obtained by injecting a radical curable composition, irradiating it with heating or active energy rays to cure it, and demolding it, but it is preferably continuous by roll-to-roll from the viewpoint of productivity and long-running property. It can be obtained by the above-mentioned photoforming method.
Such a continuous photoforming method can be performed as follows.

For example, using an applicator having a clearance that gives the required coating thickness, the radical curable composition layer is formed on the support film so as to have a desired film thickness, and the support film is brought into contact with the upper portion thereof. After preparing the laminate arranged in the above and irradiating the laminate with heating or active energy rays to cure the radical curable composition, if necessary, from both sides of the cured resin layer (plastic sheet). The support film can be peeled off to obtain a plastic sheet [I]. The feeding direction of the support film in such a step can be any of a horizontal direction, a direction perpendicular to the horizontal direction, and a direction angled from the horizontal direction. From the viewpoint of production efficiency, a method in which the film surface is horizontal and the film surface is continuously fed while being fed in the horizontal direction is preferable.

Further, in order to produce a more flexible plastic sheet, for example, the opposite surface of the support film (α) in the thickness direction of the laminate having the radical curable composition layer on the support film (α) is oxygenated. The support film (β) is arranged so as to be in contact with the oxygen-exposed surface of the radical curable composition layer in the irradiation step of irradiating the active energy rays from the support film (α) surface side in the state of being exposed to the support film. It is also possible to cure by sequentially performing an irradiation step of irradiating an active energy ray from the (β) surface side.

The layer structure of the laminate includes, for example, a three-layer structure of a support film / a curable composition / a support film, a five-layer structure of a support film / a curable composition / a support film / a curable composition / a support film, and the like. It is possible. It preferably has a three-layer structure of a support film / a curable composition / a support film in that the curing step described later proceeds efficiently.

Further, in the present invention, by winding the obtained plastic sheet [I] around a branch pipe, a plastic sheet roll which is a roll body of the plastic sheet [I] can be obtained.

The support film may be any film that does not inhibit curing by radical polymerization, but a gas barrier resin film is preferable from the viewpoint that it does not inhibit curing by oxygen.

As such a gas barrier resin film, oxygen inhibition occurs when the oxygen permeability is 200 cc / m ² · day · atm or less in an environment of 20 ° C. and dry conditions at a thickness of 20 μm of the gas barrier resin film. It is preferable in that good curing (that is, radical polymerization) can be carried out without any problem, and curing can be performed efficiently, particularly 100 cc / m ² · day · atm or less, and further 40 cc / m ² · day ·. It is preferably atm or less. If such a value is too high, good curing cannot be achieved due to oxygen inhibition, and the degree of polymerization and conversion rate tend to decrease. The lower limit is usually 0.01 cc / m ² , day, atm.

Such measurement of oxygen permeability is obtained by measuring with an oxygen permeability meter according to the measuring method shown in JIS K 7126-2: 2006.

Further, in the present invention, the support film having excellent heat resistance is preferable in consideration of the heat generated during radical curing, and the glass transition temperature of the resin constituting the support film is usually 0 ° C. or higher, particularly. It is preferably 30 ° C. or higher, more preferably 50 ° C. or higher. If the glass transition temperature is too low, it may melt and break when exposed to heat. The upper limit of the glass transition temperature is usually 400 ° C.

The thickness of the support film used in the present invention is usually 200 μm or less, more preferably 10 to 100 μm, and particularly preferably 15 to 50 μm. If the thickness is too thick, the light transmittance tends to be lowered, and the weight of the roll-shaped material tends to be too large, and if it is too thin, breakage may occur during work and safety may be impaired.

Examples of the support film as described above include a polyester resin film such as a polyethylene terephthalate film, a nylon resin film such as nylon 6 and biaxially stretched nylon, an acrylic nitrile resin film such as modified polyacrylonitrile, and a polyvinyl alcohol film. Examples thereof include a vinyl alcohol-based resin film such as a resin film and an ethylene-vinyl alcohol-based resin film, or such a uniaxially stretched or biaxially stretched vinyl alcohol-based resin film, but the vinyl alcohol-based film is particularly low in oxygen permeability. A resin film, more preferably a biaxially stretched vinyl alcohol-based resin film.

Such a vinyl alcohol-based resin film is formed by forming a film from a vinyl alcohol-based resin, and the vinyl alcohol-based resin is preferably one having a vinyl alcohol unit obtained by saponifying the vinyl ester unit. Has an average degree of saponification of 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 97 mol% or more.

Examples of the vinyl alcohol-based resin of the vinyl alcohol-based resin film include a polyvinyl alcohol-based resin (hereinafter, may be abbreviated as PVA-based resin) and an ethylene-vinyl alcohol-based copolymer (hereinafter, abbreviated as EVOH). May be done.) Can be mentioned. Further, examples of the PVA-based resin include PVA obtained by homopolymerizing vinyl acetate and saponifying it, and modified PVA, and examples of such modified PVA include copolymerized modified products and post-modified products. it can. Among the above, a biaxially stretched PVA-based resin film is particularly preferable in terms of heat resistance.

The external haze of the support film is the value obtained by subtracting the internal haze from the total haze of the object measured using the haze meter "NDH-2000" manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7361-1: 1997. (For such internal haze, haze (Hz1) is measured by sandwiching only liquid paraffin between two glass plates in advance, and then haze (Hz2) is measured by sandwiching a film whose surface is wet with liquid paraffin. It is a value calculated by taking the difference between), which is usually 0.4 or less, preferably 0.4 to 0.01, and particularly preferably 0.2 to 0.01. When the external haze value is too large, the haze value of the obtained plastic sheet [I] and the three-dimensional molded product [II] tends to be large.

The radical curable composition is usually cured (that is, radical polymerization) by irradiation with active energy rays or heat.
When curing by irradiation with active energy rays, when irradiating the curable composition with active energy rays, ultraviolet rays having a wavelength of 200 to 400 nm are usually used, and the amount of irradiation light is usually 0.1 to 0.8 J / cm ^2. Photo-cures with. A more preferable range of the irradiation light amount is 0.1 to 0.7 J / cm ² , and more preferably 0.15 to 0.5 J / cm ² . If the amount of irradiation light is too large, the curing tends to be excessive and it tends to be difficult to perform the three-dimensional molding process in the subsequent process, and if it is too small, the polymerization tends to be insufficient. The illuminance of the active energy ray is usually 10 to 2,000 mW / cm ² , particularly preferably 50 to 1,000 mW / cm ² . If the illuminance is too low, the productivity tends to decrease, and conversely, if the illuminance is too high, it tends to be difficult to control the degree of curing.

The active energy radiation source may be any one usually used for photocuring, and examples thereof include a metal halide lamp, a high-pressure mercury lamp, an electrodeless mercury lamp, and an LED-UV. In order to prevent the polymerization from running out of control due to infrared rays generated from the light source, it is also possible to use a filter that blocks infrared rays, a mirror that does not reflect infrared rays, or the like for the lamp.

When curing by heat, the heat treatment temperature is usually 30 to 140 ° C. The heat treatment time is usually 0.1 seconds to 30 minutes. If the heat treatment temperature is too low, the curing rate will be slow, and if the temperature is too high, unintended side reactions or excessive curing may occur. Further, if the heat treatment time is too long, the curing tends to be excessive and the three-dimensional molding process in the subsequent process tends to be difficult, and if it is too short, the curing tends to be insufficient.

After the above curing (that is, radical polymerization), the support film can be peeled off from both sides of the obtained plastic sheet [I] to take out only the plastic sheet [I].
The obtained plastic sheet [I] can be used as it is for a desired molding process, but it can also be wound around a branch pipe and stored as a plastic sheet roll.

It is also possible to wind the support film around a branch pipe to make a plastic sheet roll without peeling off the support film, and to prevent scratches due to blocking or friction, a polyolefin film such as polyethylene or polypropylene, polyethylene terephthalate, etc. It is also possible to wind up the polyester film, the release paper, etc. together as a separator.

The branch pipe has a diameter of usually 3 to 12 inches, preferably 3 to 6 inches, and more preferably 3 to 6 inches.

In the plastic sheet [I] of the present invention obtained above, the reaction rate of the (meth) acryloyl group is usually 50% or more and less than 75% by normal heating or irradiation with active energy rays of the radical curable composition. It is a cured product, preferably 55 to 70%, particularly preferably 60 to 70%. If the reaction rate is too low, the film thickness tends to change during storage, and if it is too high, the subsequent three-dimensional molding process tends to be difficult.

The reaction rate can be measured as follows.
That is, after freeze-crushing a test piece having a length of 50 mm and a width of 50 mm, measurement is performed using a solid-state NMR probe with "AVANCE DPX-400" manufactured by BRUKER BIOSPIN. The observation nucleus is ¹³ C, the rotation speed is 5,000 Hz, and the measurement is performed at room temperature. The carbonyl carbon in the non-polymerized (meth) acryloyl group is detected on the high magnetic field side (166 ppm), and the polymerized carbonyl carbon is detected on the low magnetic field side (176 ppm). The reaction rate (%) is calculated from these peak area ratios.

The thickness of the plastic sheet [I] of the present invention is preferably 50 to 10,000 μm, particularly 100 to 5,000 μm, further 400 to 3,000 μm, and particularly 500 to 1,000 μm. Is preferable. If the thickness is too thin, the subsequent three-dimensional molding process tends to be difficult, and if it is too thick, it tends to be difficult to roll.

The plastic sheet [I] of the present invention usually has a light transmittance of 80% or more, particularly preferably 85% or more, and more preferably 90% or more, from the viewpoint of increasing the brightness of the display. Generally, the upper limit of the light transmittance is 99%.

The plastic sheet [I] of the present invention usually has a pencil hardness of 10B or more on the surface under a load of 50g measured in accordance with JIS K 5600-5-4: 1999, particularly 8B or more, and further 7B or more. Yes, it is preferably 2B or less, particularly 4B or less. If the pencil hardness is too low, it tends to be difficult to maintain the shape of the plastic sheet, and if it is too high, the subsequent three-dimensional molding process tends to be difficult.

The plastic sheet [I] of the present invention has a total haze of usually 3% or less, particularly preferably 2% or less, more preferably 1.5% or less, from the viewpoint of high definition of the display.
Further, the external haze is usually 0.5% or less, particularly preferably 0.3% or less, and more preferably 0.15% or less.

The external haze is based on JIS K 7361-1: 1997, and is the value obtained by subtracting the internal haze from the total haze of the object measured using the haze meter "NDH-2000" manufactured by Nippon Denshoku Industries Co., Ltd. ( For such internal haze, haze (Hz1) was measured by sandwiching only liquid paraffin between two glass plates in advance, and then haze (Hz2) was measured by sandwiching a film coated with liquid paraffin on the surface. It means the value calculated by taking the difference).

In the present invention, after the plastic sheet [I] or the plastic sheet [I] unwound from the plastic sheet roll is molded, the reaction rate is usually 75% or more by normal heating or irradiation with active energy rays. It can be a molded product [II] that is hardened to.

Since the above-mentioned plastic sheet [I] of the present invention is not completely cured, it is a sheet that can be molded, and in order to give a desired design, a molding process corresponding to such a design is performed, and then usually. By heating or irradiating with active energy rays, the curing can be further advanced to obtain a molded product [II].

A known molding method can be used for the molding process. For example, a mold forming method such as press forming, vacuum forming, and pressure forming, a method of cutting out an arbitrary shape using a cutter, a knife, or the like can be mentioned.
In particular, in the present invention, a three-dimensional molded product that is molded in a direction other than a flat surface, for example, a substantially vertical direction, is obtained, whereas a conventional plastic sheet can only obtain a flat molded product. It becomes possible to obtain. Therefore, it is preferable to obtain a molded product formed by imparting an arbitrary design in a direction other than the plane, for example, a direction substantially perpendicular to the plane.

The plastic sheet [I] molded into a desired shape by a molding process is usually further cured by irradiation with active energy rays or heat to obtain a molded product [II] of the present invention.
When curing with an active energy ray, it is preferable to use ultraviolet rays having a normal wavelength of 200 to 400 nm for photocuring at a normal irradiation light amount of 0.5 to 40 J / cm ² . A more preferable range of the irradiation light amount is 5 to 35 J / cm ² , and more preferably 10 to 30 J / cm ² . If the amount of irradiation light is too large, the productivity tends to decrease, and if it is too small, the surface hardness tends to decrease. The illuminance of the active energy ray is usually 10 to 2,000 mW / cm ² , particularly preferably 50 to 1,000 mW / cm ² . If the illuminance is too low, productivity tends to decrease, and conversely, if the illuminance is too high, yellowing tends to occur.

The active energy radiation source may be any one usually used for photocuring, and examples thereof include a metal halide lamp, a high-pressure mercury lamp, an electrodeless mercury lamp, and an LED-UV, as described above. In order to prevent the polymerization from running out of control due to infrared rays generated from the light source, it is also possible to use a filter that blocks infrared rays, a mirror that does not reflect infrared rays, or the like for the lamp.

Further, heat treatment may be performed to further improve the degree of polymerization or to release stress-strain. At this time, it is preferable to heat-treat at 50 to 250 ° C. under the atmosphere or vacuum.

When curing by heating, the heat treatment temperature is usually 30 to 140 ° C. The heat treatment time is usually 0.1 seconds to 10 hours. If the heat treatment temperature is too low, curing tends to be insufficient. If the heat treatment time is too short, curing tends to be insufficient, and if it is too long, productivity may decrease and unintended side reactions may proceed.

The obtained molded product [II] of the present invention is cured by irradiation with active energy rays so that the reaction rate is usually 75% or more, preferably 80% or more, particularly preferably 85% or more. is there. If the reaction rate is too low, the surface hardness of the molded product tends to be insufficient.

The reaction rate can be measured by the same method as described above.

The thickness of the molded product [II] of the present invention is usually 50 to 10,000 μm, particularly 100 to 5,000 μm, further 400 to 3,000 μm, and particularly 500 to 1,000 μm. preferable. If the thickness is too thin, the mechanical properties tend to deteriorate, and if the thickness is too thick, the optical characteristics tend to deteriorate.

The molded product [II] of the present invention preferably has a light transmittance of usually 80% or more, particularly preferably 85% or more, and further preferably 90% or more from the viewpoint of increasing the brightness of the display. Generally, the upper limit of the light transmittance is 99%.

The molded product [II] of the present invention has a surface pencil hardness of usually 2H or more, particularly 3H or more, and further 4H or more under a load of 750 g measured in accordance with JIS K 5600-5-4: 1999. Is preferable. If the pencil hardness is too low, the plastic sheet is easily scratched and the quality of the display tends to deteriorate.

From the viewpoint of high definition of the display, the molded product [II] of the present invention preferably has a total haze of 3% or less, particularly 2% or less, and further preferably 1.5% or less.
Further, the external haze is usually 0.5% or less, particularly preferably 0.3% or less, and more preferably 0.15% or less.
The external haze means a value obtained by the same measuring method as that of the plastic sheet [I].

Thus, in the present invention, a plastic sheet having a desired film thickness can be formed, and a plastic sheet roll to be wound can be easily formed. Further, the optical characteristics and surface hardness of the molded product to be the final cured product can be determined. A molded product having excellent impact resistance can be obtained. Therefore, it is useful for applications such as protective plates for displays and three-dimensional parts around display units in copiers, automobiles, home appliances, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.
In the example, "part" and "%" mean a weight standard.
The measurement method of each physical property is as follows.

(1) Pencil hardness The pencil hardness of the plastic sheet was measured according to JIS K 5600-5-4: 1999. The load was measured at 50 g or 750 g.

(2) Total haze (%)
The measurement was performed using a haze meter "NDH-2000" manufactured by Nippon Denshoku Kogyo Co., Ltd. in accordance with JIS K 7361-1: 1997.

(3) Light transmittance (%)
The total light transmittance (%) was measured using a haze meter "NDH-2000" manufactured by Nippon Denshoku Industries Co., Ltd.

(4) Saturated water absorption rate (%)
Using a test piece having a size of 50 mm × 50 mm, the saturated water absorption rate (%) was calculated from the weight increase after immersion in water at 23 ° C. for 20 days.

(5) Impact resistance (ball drop test)
In accordance with JIS R3206 for tempered glass, the maximum value (Y) of the height that does not break even if a hard ball is dropped was obtained by performing as follows.
That is, after leaving the test piece of 50 mm in length × 50 mm in width in an environment of 23 ° C. and 50% RH for 48 hours, a ball drop tester (manufactured by Toyo Seiki Seisakusho) as shown in FIG. 1 was used to weigh 16 g in total. A hard ball having a diameter of 16 mm was dropped from a predetermined height to give an impact to the central portion of the surface of the test piece placed on a cylindrical table having a diameter of 32 mm. Increase the predetermined height in 5 cm increments, perform the same operation on 6 test pieces at each height, and set the maximum value (cm) of the height that did not break 4 or more pieces to the hard sphere. The maximum value (Y) of the height that does not break even when dropped is set.

In addition, the compounding ingredients were prepared as follows.
[Polyfunctional urethane (meth) acrylate (A) having an alicyclic structure]
(A-1): Isophorone diisocyanate 192 in a flask equipped with a hexafunctional urethane acrylate thermometer having an isophorone structure (formula (1)) obtained by the method shown below, a stirrer, a water-cooled condenser, and a nitrogen gas inlet. .0 g (0.86 mol) and 808.0 g (1.73 mol) of pentaerythritol triacrylate [mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (hydroxyl value 120 mgKOH / g)] were charged as a polymerization inhibitor. 0.01 g of hydroquinone methyl ether and 0.01 g of dibutyltin dilaurate as a reaction catalyst were charged and reacted at 60 ° C. for 8 hours. When the residual isocyanate group became 0.3% or less, the reaction was terminated to form an isophorone structure (formula (formula (formula)). A hexafunctional urethane acrylate having 1)) was obtained.

[Polyfunctional (meth) acrylate (B) having an alicyclic structure]
(B-1): Bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] Decane-dimethacrylate (“DCP” manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[(Meta) acrylic resin (C) having an alicyclic structure]
(C-1): The monomer composition obtained by blending 100 parts of dicyclopentanyl acrylate with 0.05 parts of 1-hydroxycyclohexylphenylketone and 0.05 parts of pentaerythritol tetraxthiopropionate as a photopolymerization initiator is removed. After the foam treatment, the film is sealed in a tare of a biaxially stretched polyvinyl alcohol film so that air bubbles do not enter, and after adjusting the thickness to 0.5 mm, a 2.8 mm glass plate is placed on the upper part of the tare. From above, a metal halide lamp was used to irradiate the film so that the 360 nm wavelength was 20 J / cm ² with an illuminance of 50 mW / cm ² .
Then, only the cured product was taken out from the tare of the biaxially stretched polyvinyl alcohol film and pulverized by a pulverizer. A (meth) acrylic resin powder having a monomer reaction rate of 87% and a weight average molecular weight (Mw) of 630,000 was obtained.

(C-2): A monomer composition obtained by blending 100 parts of dicyclopentanyl acrylate with 0.05 parts of 1-hydroxycyclohexylphenylketone and 1 part of pentaerythritol tetrakisthiopropionate as a photopolymerization initiator is defoamed. After that, the film is sealed in a tare of a biaxially stretched polyvinyl alcohol film so that air bubbles do not enter, and after adjusting the thickness to 0.5 mm, a 2.8 mm glass plate is placed on the upper part of the tare. The film was irradiated with a metal halide lamp so that the 360 nm wavelength was 20 J / cm ² with an illuminance of 50 mW / cm ² .
Then, only the cured product was taken out from the tare of the biaxially stretched polyvinyl alcohol film and pulverized by a pulverizer. A (meth) acrylic resin powder having a monomer reaction rate of 90% and a weight average molecular weight (Mw) of 50,000 was obtained.

(C'-1): After defoaming a monomer composition prepared by blending 100 parts of dicyclopentanyl acrylate with 0.05 parts of 1-hydroxycyclohexylphenylketone as a photopolymerization initiator, the bubbles are prevented from entering. After sealing in a tare of biaxially stretched polyvinyl alcohol film and adjusting the thickness to 0.5 mm, a 2.8 mm glass plate is placed on the top of the tare, and a metal halide lamp is used from above to achieve a 360 nm wavelength of 50 mW. was irradiated so that 20 J / cm ² at an intensity of / cm ^2.
Then, only the cured product was taken out from the tare of the biaxially stretched polyvinyl alcohol film and pulverized by a pulverizer. A (meth) acrylic resin powder having a monomer reaction rate of 83% and a weight average molecular weight (Mw) of 1.3 million was obtained.

[Polymerization initiator (D)]
(D-1): 1-Hydroxycyclohexylphenylketone

[Mercapt group-containing compound (E)]
(E-1): Pentaeritol = Tetrakis (3-Sulfanyl butanoart) (Showa Denko KK "Karensu MT PE-1")

<Examples 1 to 5, Comparative Example 1>
[Preparation of radical curable composition]
As shown in Table 1, each component was mixed, stirred at 60 ° C. until uniform, and then filtered through a 42 μm filter to obtain a radically polymerizable composition. The composition viscosity at this time was determined by using a cone-plate type viscometer (trade name "TPE-100", manufactured by Toki Sangyo Co., Ltd.), Peltier plate temperature: 23 ° C, cone rotor used: 3 ° x. It was measured by R14.

[Preparation of Plastic Sheet and Plastic Sheet Roll in Examples 1 and 2 and Comparative Example 1]
A coating film of a radically polymerizable composition was continuously formed on a 38 μm-thick polyethylene terephthalate film continuously conveyed in the horizontal direction using an applicator having a clearance of 880 μm. A 38 μm-thick polyethylene terephthalate film was separately attached onto the coating film, and the 25 μm-thick biaxially stretched polyvinyl alcohol film was overlaid with a metal halide lamp using an ultraviolet measuring device at a wavelength of 360 nm at 50 mW / cm ² . The film was transported while being irradiated with ultraviolet rays so that the exposure amount was 250 mJ / cm ² at the irradiation intensity. Then, the polyethylene terephthalate film / plastic sheet / polyethylene terephthalate film laminate was wound around a branch pipe to obtain a roll-like composition (plastic film roll). Various physical properties of the plastic sheet were measured with the support films on both sides peeled off.

[Preparation of Plastic Sheet and Plastic Sheet Roll in Examples 3 to 5]
A coating film of the radical curable composition was continuously formed on a 38 μm-thick polyethylene terephthalate film (α) continuously conveyed in the horizontal direction using an applicator having a clearance of 880 μm. From the 38 μm-thick polyethylene terephthalate film (α) surface side, use a UV-LED (365 nm) lamp with an ultraviolet measuring device at a wavelength of 360 nm. Ultraviolet rays with an irradiation intensity of 1500 mW / cm ² and an irradiation light amount of 200 mJ / cm ^2. It was transported while irradiating. A 38 μm-thick polyethylene terephthalate film (β) is arranged so as to be in contact with the oxygen-exposed surface of the radical curable composition layer, and a UV-LED lamp is used from the 38 μm-thick polyethylene terephthalate film (β) surface side at a wavelength of 360 nm. It was conveyed by an ultraviolet measuring device while irradiating ultraviolet rays at an irradiation intensity of 200 mW / cm ² and an irradiation light amount of 100 mJ / cm ² . Then, the polyethylene terephthalate film (α) / plastic sheet / polyethylene terephthalate film (β) laminate was wound around a branch pipe to obtain a roll-shaped composition (plastic film roll). Various physical properties of the plastic sheet were measured with the base film on both sides peeled off.

Various physical properties of the obtained plastic sheet were evaluated, and the results are shown in Table 2.
The plastic sheet obtained in the examples is referred to as [I], and the plastic sheet obtained in the comparative example is referred to as [I'].

[Making a molded product]
A certain amount was cut out from the above plastic sheet roll. The plastic sheet was irradiated with ultraviolet rays so as to have an illuminance of about 5,000 mW / cm ² at 360 nm and 20 J / cm ² , and cured to obtain a molded product model. After that, the support film is peeled off, and only the molded product model is brought into contact with the metal skeleton around the dryer under a vacuum of 0.1 Torr (that is, about 13.332 Pa) or less at 200 ° C. using a vacuum dryer. And annealed for 6 hr.
Various physical properties of the obtained molded product model were evaluated, and the results are shown in Table 2.

In addition, although such a molded product model is not molded so as to impart designability in the direction perpendicular to the plane of the plastic sheet, when the designability is imparted, it is applied to the surface of the plastic sheet [I] or [I']. As long as the unevenness and impurities do not adhere, the presence or absence of the design property does not affect the various physical properties of the molded product, so that the molded product is equivalent to the molded product molded with the design property. The molded product obtained in the examples is referred to as [II], and the molded product obtained in the comparative example is referred to as [II'].
The evaluation results of Examples and Comparative Examples are shown in Table 2.

As can be seen from the above results, a radical curable composition containing a polyfunctional urethane (meth) acrylate having an alicyclic structure, a polyfunctional (meth) acrylate having an alicyclic structure, and a polymerization initiator is further added to 5 In Examples 1 to 5, the viscosity of the radical curable composition can be increased by containing a (meth) acrylic resin having an alicyclic structure having a medium molecular weight such as 10,000 to 700,000. Therefore, a plastic sheet obtained by curing can be easily formed, and a uniform film thickness can be ensured. Further, it was possible to obtain a molded product having excellent optical properties, surface hardness and impact resistance of the molded product as the final cured product, and its saturated water absorption rate was as low as 1%.
Also, regarding the impact resistance of the molded product, the height at which there is no crack due to the falling of the hard ball is 5 to 10 cm higher in Examples 1 to 5 than in Comparative Example 1, and in Examples 1 to 5, the height is dropped from a higher position. It turns out that it can withstand. Further, it can be said that a product that can withstand a drop test from a higher position can withstand a larger number of drops when evaluated at the same height. For example, the molded product of the present invention can be carried as a display member, especially a portable member. When used for a touch panel board of a terminal or the like, it is considered that it can withstand a large number of drops.

A plastic sheet made of the radical curable composition of the present invention and a molded product obtained by further curing the plastic sheet can be advantageously used for various optical materials and electronic materials. For example, liquid crystal substrates, organic / inorganic EL substrates, electronic paper substrates, light guide plates, retardation plates, touch panels, and other display members, optical disk substrates, optical disk film coatings, and other storage / recording applications, thin films. It can be used for energy applications such as battery substrates and solar cell substrates, optical communication applications such as optical waveguides, and various optical film sheet coating applications such as functional films / sheets, antireflection films, and optical multilayer films. Above all, it is highly expected as a protective plate for displays and a capacitive touch panel substrate.

Claims (7)

The following components (A), (B), (C) , (D) and (E) are contained, and the content ratio of each component (A) to (E) satisfies the following [i] to [iv]. A radical curable composition comprising.
(A) Polyfunctional urethane (meth) acrylate having an alicyclic structure (B) Polyfunctional (meth) acrylate having an alicyclic structure (however, the component (A) is excluded)
(C) (Meta) acrylic resin having an alicyclic structure having a weight average molecular weight of 50,000 to 700,000 (D) Polymerization initiator
(E) Mercapto group-containing compound
[I] The blending ratio of the component (A) and the component (B) is (A) :( B) = 10: 90 to 50:50 (weight ratio).
[Ii] The content of the component (C) is 1 to 30 parts by weight with respect to a total of 100 parts by weight of the component (A) and the component (B).
[Iii] The content of the component (D) is 0.1 to 5 parts by weight based on 100 parts by weight of the total of the component (A) and the component (B).
[Iv] The content of the component (E) is 10 parts by weight or less with respect to a total of 100 parts by weight of the component (A) and the component (B). The alicyclic structure having a (meth) acrylic resin (C) is radical curable composition according to claim 1 Symbol mounting, characterized in that a homopolymer of mono (meth) acrylate (c1) having an alicyclic structure object. The radical curable composition according to claim 1 or 2 , wherein the viscosity at 23 ° C. is 100 to 20,000 mPa · s. A plastic sheet obtained by curing the radical curable composition according to any one of claims 1 to 3 , wherein the reaction rate of the (meth) acryloyl group is 50% or more and less than 75%. Sheet. The plastic sheet according to claim 4 , wherein the thickness is 50 to 10,000 μm. A plastic sheet roll according to claim 4 or 5, wherein the plastic sheet is wound. A molded product obtained by molding the plastic sheet according to claim 4 or 5 or the plastic sheet unwound from the plastic sheet roll according to claim 6 , wherein the reaction rate of the (meth) acryloyl group is 75% or more. A molded product characterized by that.

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