JPH11322848A - Optical member having low birefringence and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject optical member having excellent impact resistance and useful as a plate for a liquid crystal display panel capable of forming a sheet of large area by polymerizing and curing a specific alicyclic hydrocarbon skeleton bis(meth)acrylate, a prescribed mercapto compound and a specified organic peroxide. SOLUTION: This optical member comprises a photopolymerized and cured substance of a composition comprising (A) 92-99.9 pts.wt. of an alicyclic hydrocarbon skeleton bis(meth)acrylate of formula I (R<1> and R<2> are each H or CH3 : (p) is 1 or 2; (q) is 0 or 1), (B) 0.1-0.8 pts.wt. of at least one selected from mercapto compounds of formula II (R<3> is CH2 or the like; R<4> is a 2-15C hydrocarbon residue or the like; (a) is 2-6) and formula III [X is HS-(CH2 -)b (CO)-(OCH2 CH2 )d -(CH2 )c ((b) and (c) are each 1-8; (c) is 0-2)] and (C) 0.01-1.0 pt.wt. based on 100 pts.wt. of the whole monomer components of an organic peroxide of formula IV (R<5> and R<6> are each a hydrocarbon; (e) is 0 or 1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member, and more particularly to a high impact resistant low birefringent optical member suitable for a liquid crystal display panel.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display panel using a glass plate as a substrate has been demanded because such a panel is limited in terms of reduction in glass density and improvement in mechanical strength. It is difficult to cope with light weight and thinness. Further, problems have been pointed out from the viewpoints of moldability and workability regarding the improvement of productivity, and attention has been paid to panels using plastic as a substrate. However, the plastic substrate has the following problems. Lack of transparency and optical isotropy suitable for liquid crystal display. Poor heat resistance.

In particular, with respect to optical isotropy, the current state is that the birefringence Δn · d of a glass plate is 1 nm or less, while that of a plastic plate exceeds 10 nm. This problem of birefringence is difficult to solve by a molding method in which some stretching operation or material flow operation is performed on resin, and when a relatively thick substrate (for example, 0.4 mm or more) is used, Extrusion molding or belt molding of a thermoplastic resin is difficult to mold. On the other hand, when a thermosetting resin is used, there is a production problem that a molding time is several hours.

As a means for solving this problem, there are two or more radically reactive unsaturated bonds in the molecule ((meth))
A method for obtaining a low-birefringence optical member by polymerizing and curing a resin composition comprising an acrylate compound and a mercapto compound having two or more thiol groups in a molecule with an active energy ray in the presence of a photo-radical polymerization initiator is proposed. (Japanese Patent Application No. 9-152510). This system has superior impact resistance as compared with a glass substrate, and is preferably used as a substrate of a liquid crystal display panel. there were. In particular, cracking and chipping due to insufficient mechanical strength of the substrate in the demolding step after the molding of a large area sheet of A3 size or more was a major factor in lowering the yield.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a low birefringence optical member such as a liquid crystal display panel plate having excellent impact resistance and capable of forming a large area sheet. It is in.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above problems, and as a result, have found that an alicyclic hydrocarbon skeleton having two or more radically reactive unsaturated bonds in the molecule. By polymerizing and curing a (meth) acrylate compound, a mercapto compound having two or more thiol groups in a molecule, and an organic peroxide having a specific structure, an intended high impact resistant and low birefringent optical member can be obtained. This has led to the present invention. That is, the present invention provides the following low birefringence optical member and a method for manufacturing the same. A low birefringent optical member comprising a photopolymerized cured product of a composition containing the following components A, B and C. Component (A): 92 to 99.9 parts by weight of an alicyclic hydrocarbon skeleton bis (meth) acrylate represented by the following general formula [I].

[0007]

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[R ¹ and R ² may be the same or different and each is hydrogen or CH ₃ , p is an integer of 1 or 2, q is 0 or 1] Component (B): The following formulas [II] and [II] III] 0.1 to 8 parts by weight of at least one mercapto compound selected from the group consisting of:

[0009]

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[R ³ is —CH ₂ — or —CH ₂ CH ₂
And R ⁴ is a C _2-15 hydrocarbon residue or an alkyl ether residue, and a is an integer of 2 to 6]

[0011]

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[X is HS- (CH _2- ) _b (CO)-
(OCH ₂ CH ₂ ) _d- (CH ₂ ) _c- (b, d is 1 to
An integer of 8 and c is from 0 to 2)] Component (C): 0.01 to 100 parts by weight of an organic peroxide represented by the following general formula [IV] and 100 parts by weight of all monomer components.
1.0 parts by weight.

[0013]

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[R ⁵ and R ⁶ may be the same or different and each is a hydrocarbon group which may contain oxygen and / or an aromatic ring, and e is 0 or 1]

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photopolymerization of a polymerizable composition containing a specific alicyclic hydrocarbon skeleton bis (meth) acrylate monomer, a specific mercapto compound and a specific organic peroxide. The present invention relates to a low birefringence optical member made of a cured product and a method for producing the same. Here, “comprising” means that a small amount of auxiliary components may be contained as long as the gist of the present invention is not impaired. That is, another monomer copolymerizable with the component specified in the present invention is specifically added, for example, 3 parts per 100 parts by weight of the specified three components.
It means that it may be used in an amount of up to about 0 parts by weight. In addition, each component may be used in combination between and / or within the components. Note that “(meth) acryl” and “(meth) acrylate” are generic terms for acryl or methacryl and acrylate or methacrylate. <Component (A): bis (meth) acrylate> Component (A)
Is an alicyclic hydrocarbon skeleton bis (meth) acrylate represented by the formula [I].

[0016]

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The symbols in the formula have the following meanings. R ¹ and R ² : a hydrogen atom or a methyl group. R ¹ , R ²
May be the same or different. p: an integer of 1 or 2. q: 0 or 1.

The alicyclic hydrocarbon skeleton represented by the formula [I]
Examples of the (meth) acrylate compound include bis
(Oxymethyl) tricyclo [5.2.1.0^2,6]
Can = diacrylate, bis (oxymethyl) trisic
B [5.2.1.0^2,6Decane dimethacrylate,
Bis (oxymethyl) tricyclo [2.2.1.
0^{2, 6}] Decane = acrylate methacrylate and this
Their mixture, bis (oxymethyl) pentacyclo
[6.5.1.1^3,6. 0^2,7. 0^9,13] Pentadecane
= Diacrylate, bis (oxymethyl) pentacyclo
[6.5.1.1^3,6. 0 ^2,7, 0^9,13] Pentadecane
= Dimethacrylate, bis (oxymethyl) pentacyclic
B [6.5.1.1^3,6. 0^2,7, 0^9,13] Pentadeca
= Acrylate methacrylate and mixtures thereof
And the like. These tricyclodecane compounds and
And pentacyclodecane compounds are within a group and / or
Two or more of them may be used in combination. These compounds
For example, the hand disclosed in Japanese Patent Application Laid-Open No. 62-225508 is disclosed.
It can be synthesized by a method.

<Component (B): Mercapto Compound> The component (B) contains 2 units in the molecule represented by the formulas [II] and [III].
It is at least one or more mercapto compounds selected from mercapto compounds having two or more thiol groups.

[0020]

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The symbols in the formula have the following meanings. R ³ : a methylene group or an ethylene group. R ⁴ : a hydrocarbon residue having 2 to 15 carbon atoms which may contain ether oxygen and thioether sulfur. Preferably 2 to 2 carbon atoms
6 hydrocarbon residues. a: an integer of 2 to 6. X: HS- (CH _2- ) _b (CO)-(OCH ₂ C
_{H 2) d - (CH 2} ) c - (b, d is an integer of 1 to 8, c
Is 0-2)

The mercapto compound represented by the formula [II] is
For example, divalent to hexavalent thioglycolic acid ester or
Hexavalent thiopropionates can be mentioned,
These are preferred compounds. Specific examples of the compound of the formula [II] include, for example, pentaerythritol tetrakis (β-thiopropionate), pentaerythritol tetrakis (thioglycolate), trimethylolpropane tris (β-thiopropionate), trimethylolpropane Tris (thioglycolate), diethylene glycol bis (β-thiopropionate), diethylene glycol bis (thioglycolate), triethylene glycol bis (β-thiopropionate), triethylene glycol (thioglycolate), dipenta Erythritol hexakis (β-thiopropionate) and dipentaerythritol hexakis (thioglycolate).

The compound of the formula [III] is, for example, ω-SH
Group-containing isocyanurates can be mentioned, and these are preferred compounds. Specific examples of the compound of the formula [III] include, for example, tris [2- (β-thiopropionyloxy) ethyl] isocyanurate, tris (2-thioglyconyloxyethyl) isocyanurate, tris [2- (β- Thioglyconyloxyethoxy) ethyl]
Isocyanurate, tris (2-thioglyconyloxyethoxyethyl) isocyanurate, tris [3- (β
-Thiopropionyloxy) propyl] isocyanurate, tris (3-thioglyconyloxypropyl) isocyanurate and the like.

The alicyclic hydrocarbon skeleton bis (meth) acrylate of the component (A) can be polymerized by itself, but the cured resin obtained has large birefringence and mechanical strength such as impact resistance. There is a disadvantage that is inferior. By blending the mercapto compound of the component (B) represented by the general formulas [II] to [III], the thiol group in the mercapto compound acts as a chain transfer agent, and the polymerization hardens smoothly and uniformly. In addition, the birefringence of the cured resin can be greatly reduced. Further, it can enter the three-dimensional network structure formed by the alicyclic hydrocarbon skeleton bis (meth) acrylate compound of the above [I], and can impart appropriate toughness. In the present invention, the above-mentioned problem of birefringence is first solved without greatly impairing the heat resistance of the obtained cured product, because it has two or more thiol groups in the molecule, that is, uses a polyfunctional mercapto compound. can do.

The composition ratio of the mercapto compound in the present invention is from 0.1 to 8 parts by weight, preferably from 1 to 8 parts by weight, based on 100 parts by weight of all the monomer components. If the proportion of the mercapto compound is too small, the effect of improving the birefringence of the cured resin will not be obtained, and if it is too large, the heat resistance of the cured resin will be low.

<Component (C): Organic peroxide> Component (C)
Is an organic peroxide represented by the formula [IV].

[0027]

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The symbols in the formula have the following meanings. R^Five, R⁶: May contain oxygen and / or aromatic ring
Hydrocarbon groups. R^Five, R ⁶May be the same or different. e: 0 or 1. Specific examples of the organic peroxide represented by the formula [IV] include:
-T-butyl peroxide, t-butyl cumyl peroxy
Sid, dicumyl peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane, bis
(T-butylperoxyisopropyl) benzene, t-
Butyl peroxyacetate, t-butyl peroxyi
Sobutyrate, t-butyl peroxy neodecanoe
G, t-butyl peroxy-2-ethylhexanoe
G, t-butylperoxy-3,5,5-trimethyl
Xanoate, t-butylperoxylaurate, t-
Butylperoxybenzoate, t-butylperoxy
Maleic acid, t-butyl peroxyisopropylcarbo
Nate, t-butyl peroxyneohexanoate, di
-T-butylperoxyisophthalate, 2,5-dimethyl
Tyl-2,5-di (benzoylperoxy) hexane,
t-hexyl peroxyneohexanoate, t-hex
Silperoxy neodecanoate, cumyl peroxyne
Odecanoate, cumyl peroxy octoate, kumi
Luperoxy neohexanoate, and mixtures thereof
Is mentioned.

Of these compounds, those having a half-life at 50 ° C. of 100 hours or more and a half-life at 100 ° C. of 1 hour to 20 hours are more preferably used. Butyl peroxyacetate, t-butyl peroxyisobutyrate, t
-Butylperoxy-2-ethylhexanoate, t-
Butylperoxybezoate, di-t-butylperoxyisophthalate, t-butylperoxymaleic acid,
t-butyl peroxyisopropyl carbonate and mixtures thereof, and the like.

The present invention is characterized by blending the organic peroxide of the component (C). By blending the organic peroxide of the component (C), the mechanical strength such as the impact resistance of the cured product can be significantly improved. The mechanism by which mechanical strength such as impact resistance is improved is not always clear,
The component (C) is decomposed by the heat of reaction generated in the active energy ray curing process to generate radicals and the component (A)
In addition, the cured network molecular chains generated by the component (C), which promote the curing of the component (B), have a length greater than the length of the cured network molecular chains generated by the active energy rays. As a result, it is presumed that, as a result, the portions having different elastic moduli are appropriately dispersed in the cured product, thereby improving the mechanical strength of the cured product.

In the present invention, the composition ratio of the organic peroxide is 0.01 to 1.
0 parts by weight, preferably 0.1 to 0.5 parts by weight, more preferably 0.2 to 0.3 parts by weight. If the proportion of the organic peroxide is too small, the effect of improving the mechanical strength such as the impact resistance of the cured resin cannot be obtained, and if it is too large, the hue of the cured resin is deteriorated, and the mechanical strength is decreased. But not preferred.

The half life of the organic peroxide of the present invention at 50 ° C. is more preferably 100 hours or more. If it is less than 100 hours, the storage stability at room temperature tends to decrease. The half life of the organic peroxide at 100 ° C. in the present invention is more preferably 1 hour or more and 20 hours or less. If the half-life at 100 ° C. is shorter than this, the rate of acceleration of curing may be too high, and sink and distortion may easily occur in the cured resin molded product.
Conversely, if the length is long, the effect of improving the mechanical strength such as the impact resistance of the cured resin tends to be small.

<Auxiliary Component> The low birefringence material according to the present invention is obtained by polymerizing and curing a composition containing components (A), (B) and (C), and this composition comprises a small amount of an auxiliary component. May be included as described above. Therefore, the resin composition for a low birefringence member of the present invention is obtained by mixing and copolymerizing other radically polymerizable monomers in an amount up to about 30 parts by weight with respect to 100 parts by weight of the composition before curing. It is also possible to manufacture. Other monomers used at this time include, for example, methyl (meth) acrylate, phenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, methacryloyloxymethyltetracyclodecane, methacryloyloxymethyltetracyclododecene, ethylene Glycol di (meth) acrylate, diethylene glycol di (meth) acrylate,
1,6-hexenediol di (meth) acrylate,
2,2-bis [4- (β-methacryloyloxyethoxy) phenyl] propane, 2,2′-bis [4- (β-
(Meth) acrylate compounds such as methacryloyloxyethoxy) cyclohexyl] propane, 1,4-bis (methacryloyloxymethyl) cyclohexane, and trimethylolpropane tri (meth) acrylate; styrene, chlorostyrene, divinylbenzene, and α-methylstyrene; Core and / or side chain substituted and unsubstituted styrene and the like. Among these other monomers, methacryloyloxymethylcyclododecane, 2,2-bis [4- (β-methacryloyloxyethoxy) phenyl] propane, 2,2-bis [4- (β-methacryloyloxyethoxy) cyclohexyl ] Propane, 1,4
-Bis (methacryloyloxymethyl) cyclohexane, and mixtures thereof, are particularly preferred. Other auxiliary components include antioxidants, ultraviolet absorbers, dyes and pigments, plasticizers, fillers, thixotropy-imparting agents, mold release agents, defoamers, and leveling agents.

<Polymerization Curing> The composition comprising the components A, B and C in the present invention is molded and cured. The curing is desirably performed by a radical polymerization method in which a photopolymerization initiator that generates radicals by active energy rays such as ultraviolet rays is added. Examples of the photopolymerization initiator used at that time include benzophenone, benzoin methyl ether, benzoin isopropyl ether, diethoxyacetophenone,
-Hydroxycyclohexyl phenyl ketone, 2,6-
Dimethylbenzoyldiphenylphosphine oxide,
2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like. Preferred photopolymerization initiators are 2,4,6-trimethylbenzoyldiphenylphosphine oxide M and benzophenone.

Two or more photopolymerization initiators may be used in combination. The addition amount of these photopolymerization initiators is 100
0.01 to 1 part by weight, preferably 0.02 part by weight based on part by weight
０．３0.3 parts by weight. If the amount of the photopolymerization initiator is too large, the polymerization proceeds rapidly, causing not only an increase in birefringence but also a deterioration in hue. If the amount is too small, the composition cannot be cured sufficiently. The amount of the active energy rays to be irradiated is arbitrary as long as the photopolymerization initiator generates radicals.However, when the amount is extremely small, the heat resistance and mechanical properties of the cured product are sufficiently exhibited due to incomplete polymerization. On the contrary, if the amount is extremely excessive, deterioration of the cured product due to light, such as yellowing, occurs. Irradiate in the range of 1 to 200 j. It is more preferable to irradiate the active energy ray in a plurality of times. That is, when the first irradiation is performed for about 1/20 to 1/3 of the total irradiation amount, and when the required remaining amount is irradiated for the second and subsequent times, a cured product having smaller birefringence is obtained. Specific examples of the lamp to be used include a metal halide lamp and a high-pressure mercury lamp.

For the purpose of promptly completing the curing, thermal polymerization may be used in combination. That is, the composition and the entire mold are heated in the range of 30 to 300 ° C. simultaneously with the light irradiation. In this case, a radical polymerization initiator may be added in order to complete the polymerization better, but excessive use causes an increase in birefringence and a deterioration in hue. Specific examples of the thermal polymerization initiator include benzoyl peroxide, diisopropyl peroxycarbonate, and the like, and the amount is preferably 1 part by weight or less based on 100 parts by weight of the monomer.

Further, in the present invention, the completion of the polymerization reaction and the internal strain generated during the polymerization can be reduced by heating the cured product after performing the radical polymerization by light irradiation. The heating temperature is appropriately selected according to the composition of the cured product and the glass transition temperature. However, since excessive heating results in deterioration of the hue of the cured product, a temperature around the glass transition temperature or lower is preferable.

A gas barrier film can be formed on the surface of the cured product obtained by the present invention by various methods, and can be used as an optical member with a gas barrier. Known gas barrier films can be used.
For example, a single layer or a stack of silicon oxide such as SiOx, PVA, an acrylic resin, or the like can be used.

Various transparent conductive films can be formed on the surface of the cured product obtained by the present invention by various methods, and can be used as optical members with transparent electrodes.
There is no particular limitation on the transparent conductive film that can be formed on the surface of the cured product. For example, Au, Ag, Cu, Pd, Al, Cr, R
h, etc., In ₂ O ₃ , SnO ₂ , Cd ₂ Sn
O _4, oxides semiconductive film such as CdO and the like. Of these, In ₂ O ₃ , SnO ₂ and Cd ₂ SnO ₄ are preferred in terms of conductivity, transparency and film strength, and so-called ITO in which In ₂ O ₃ is doped with Sn is most preferred. The method for forming the transparent conductive film is not particularly limited, and examples thereof include a spray method, a gas phase reaction method (CVD method),
Examples include a chemical film forming method such as a coating method, and a physical film forming method such as a vacuum evaporation method and a sputtering method.

The optical member obtained by the present invention has low birefringence, good impact resistance, and excellent transparency. Therefore, it can be used for many optical members such as a display panel plate, a liquid crystal panel plate, various lenses, a prism optical fiber, an optical filter, and an optical disk. In addition, the optical member with a transparent electrode obtained by the present invention has excellent adhesion to the surface of the cured product of the transparent conductive film and excellent transparency, so that it can be advantageously used for a display panel plate, a liquid crystal panel plate and the like.

[0041]

The following examples serve to illustrate the present invention more specifically. Parts in the examples indicate parts by weight. Various physical properties of the cured product described in the examples were measured by the following test methods. (1) Light transmittance The light curing rate at 500 nm was measured. (2) Birefringence The birefringence was measured at 25 ° C. using a birefringence measuring device (manufactured by Oak). (3) Heat resistance In the Vicat softening test, a sample in which the indenter penetrated 0.3 mm or more at 120 ° C. or less was evaluated as ×, and a sample that did not enter was evaluated as ○. Indenter cross-sectional area 1.0mm ² , load 5k
g, heating rate 50 ° C./Hr. (4) Flexural modulus 3 cm between fulcrum points for a 1 cm wide plate
cm at 25 ° C. using an autograph tester. (5) Impact resistance A 40 mm square plate was used as a sample, and 8 g of steel balls were dropped to a height of 10 using a falling ball tester (manufactured by Tokyo Seimitsu Co., Ltd.).
The sample is dropped from the position of cm to give an impact to the sample. The position where the steel ball is dropped is raised by 10 cm, and the ball is dropped repeatedly until it breaks. Falling ball impact strength = (falling ball height when sample is broken) −10 cm. (6) Demolding property The cured product having cracks when demolding was rated as x. (7) Oxygen Permeability According to ASTN D3985, using OX-TRAN100 of Modern Control, 23
It measured under the conditions of ° C-80% RH. (8) Resistance value Measured using Mitsubishi Chemical Loresta.

Example 1 bis (oxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = 95 parts of dimethacrylate, 5 parts of pentaerythritol tetrakis (β-thiopropionate), t-butyl After uniformly stirring and mixing 0.2 parts of peroxyisobutyrate, 0.05 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Lucillin TPO” manufactured by BASF) as a photoinitiator, and 0.02 parts of benzophenone. The mixture was defoamed to obtain a composition. This composition was poured into a mold composed of two optically polished glass plates and a 1 mm thick silicon spacer,
Output 40W / c above and below the glass surface at a distance of 40cm
UV irradiation was performed for 1 minute between metal halide lamps of m and m, followed by irradiation for 5 minutes between metal halide lamps having an output of 80 W / cm. Demold after UV irradiation, 1
The cured product was obtained by heating at 20 ° C. for 1 hour. Various properties of the cured product were as shown in Table 1.

Example 2 The procedure of Example 1 was repeated except that 5 parts of tris [2- (β-thiopropionyloxy) ethyl] isocyanurate was used instead of 5 parts of pentaerythritol tetrakis (β-thiopropionate). A cured product was obtained in the same manner. Various properties of the cured product were as shown in Table 1.

Example 3 On the cured product having a thickness of 1 mm obtained in Example 1, 200 Å of SiO ₂ was formed by a sputtering apparatus (Tokuda Seisakusho; Model CFS-4ES). Various properties of the obtained sheet were as shown in Table 1. The obtained sheet has an oxygen permeability of 1 cc.
/ M was ² · 24h · atm.

Example 4 An ITO film was formed on the cured product having a thickness of 1 mm obtained in Example 1 by using a sputtering apparatus (Tokuda Seisakusho; Model CFS-4ES) at 1500 angstrom. Various properties of the obtained sheet were as shown in Table 1. The surface resistance of the obtained sheet was 30Ω.
/ □.

Example 5 On the cured product having a thickness of 1 mm obtained in Example 1, a 200 angstrom film of SiO ₂ was formed by a sputtering apparatus (Tokuda Seisakusho; type CFS-4ES), and the same process was performed thereon. 1 ITO using device
A 500 angstrom film was formed. Various properties of the obtained sheet were as shown in Table 1. The obtained sheet had an oxygen permeability of 1 cc / m ² · 24 h · atm,
The surface resistance was 30Ω / □.

COMPARATIVE EXAMPLE 1 Using 100 parts of bis (oxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = dimethacrylate, no mercapto compound and no organic peroxide were used, and A cured product was obtained in the same manner as in Example 1. Various properties of the cured product were as shown in Table 1.

Comparative Example 2 Using 95 parts of bis (oxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane dimethacrylate and 5 parts of pentaerythritol tetrakis (β-thiopropionate), A cured product was obtained in the same manner as in Example 1 without blending an organic peroxide. Various properties of the cured product were as shown in Table 1.

Comparative Example 3 Bis (oxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = 80 parts of dimethacrylate, 20 parts of pentaerythritol tetrakis (β-thiopropionate), t-butyl A cured product was obtained in the same manner as in Example 1 except that 0.1 part of peroxyisobutyrate was used. Various properties of the cured product were as shown in Table 1.

Comparative Example 4 A cured product was obtained in the same manner as in Example 1 except that 0.2 parts of benzoyl peroxide was used instead of 0.2 parts of t-butylperoxyisobutyrate. Various properties of the cured product were as shown in Table 1.

[0051]

[Table 1]

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02F 1/1333 500 G02B 1/10 Z

Claims (7)

[Claims] 1. A low birefringence optical member comprising a photopolymerized cured product of a composition containing the following components A, B and C. Component (A): 92 to 99.9 parts by weight of an alicyclic hydrocarbon skeleton bis (meth) acrylate represented by the following general formula [I]. Embedded image [R ¹ and R ² may be the same or different and each is hydrogen or CH ₃ , p is an integer of 1 or 2, q is 0 or 1] Component (B): From the following formulas [II] and [III] 0.1 to 8 parts by weight of at least one or more selected mercapto compounds. Embedded image [R ³ represents -CH ₂ -or -CH ₂ CH _2- ;
⁴ is a C _2-15 hydrocarbon residue or alkyl ether residue,
a is an integer of 2 to 6] [X is HS- (CH _2- ) _b (CO)-(OCH ₂ CH
_{2) d - (CH 2)} c - (b, d is an integer of 1 to 8, c is 0 to 2)] Component (C): an organic peroxide represented by the following general formula [IV], all the monomer components 0.01 to 100 parts by weight
1.0 parts by weight [R ⁵ and R ⁶ may be the same or different, and each may be a hydrocarbon group which may contain oxygen and / or an aromatic ring,
e is 0 or 1] 2. The organic peroxide according to claim 1, wherein the half life at a temperature of 50 ° C. is 100 hours or more, and the half life at a temperature of 100 ° C. is 1 hour or more and 20 hours or less. The low birefringence optical member according to the above. 3. The low birefringence optical member according to claim 1, wherein the low birefringence optical member is a plate for a liquid crystal display panel. 4. The low birefringence optical member according to claim 1, wherein a gas barrier film is formed on the surface of the photopolymerized cured product. 5. The low birefringence optical member according to claim 1, wherein a transparent electrode is formed on the surface of the photopolymerized cured product. 6. The low birefringence optical member according to claim 1, wherein a gas barrier film and a transparent electrode film are laminated on the surface of the photopolymerized cured product. 7. A method for producing a low birefringence optical member, comprising irradiating an active energy ray to a composition containing the following components A, B and C to carry out photopolymerization and curing. Component (A): 92 to 99.9 parts by weight of an alicyclic hydrocarbon skeleton bis (meth) acrylate represented by the following general formula [I]. Embedded image [R ¹ and R ² may be the same or different and each is hydrogen or CH ₃ , p is an integer of 1 or 2, q is 0 or 1] Component (B): From the following formulas [II] and [III] 0.1 to 8 parts by weight of at least one or more selected mercapto compounds. Embedded image [R ³ represents -CH ₂ -or -CH ₂ CH _2- ;
⁴ is a C _2-15 hydrocarbon residue or alkyl ether residue,
a is an integer of 2 to 6] [X is HS- (CH _2- ) _b (CO)-(OCH ₂ CH
_{2) d - (CH 2)} c - (b, d is an integer of 1 to 8, c is 0 to 2)] Component (C): an organic peroxide represented by the following general formula [IV], all the monomer components 0.01 to 100 parts by weight
1.0 parts by weight [R ⁵ and R ⁶ may be the same or different, and each may be a hydrocarbon group which may contain oxygen and / or an aromatic ring,
e is 0 or 1]