U.S. patent application number 09/910900 was filed with the patent office on 2002-03-14 for methyl methacrylate resin composition and molded article thereof.
This patent application is currently assigned to SUMITOMO CHEMICAL COMPANY, LIMITED. Invention is credited to Maekawa, Tomohiro, Manabe, Kenji.
Application Number | 20020032285 09/910900 |
Document ID | / |
Family ID | 26596786 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020032285 |
Kind Code |
A1 |
Maekawa, Tomohiro ; et
al. |
March 14, 2002 |
Methyl methacrylate resin composition and molded article
thereof
Abstract
The present invention provides a methyl methacrylate resin
composition exhibiting superior durability without impairing the
transparency inherent to a methyl methacrylate resin, which
comprises a methyl methacrylate resin and a 2-(1-arylalkylidene)
malonic acid ester in an amount of 0.0005 to 0.1 parts by weight
per 100 parts by weight of the methyl methacrylate resin.
Inventors: |
Maekawa, Tomohiro;
(Niihama-shi, JP) ; Manabe, Kenji; (Niihama-shi,
JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN,
MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Assignee: |
SUMITOMO CHEMICAL COMPANY,
LIMITED
|
Family ID: |
26596786 |
Appl. No.: |
09/910900 |
Filed: |
July 24, 2001 |
Current U.S.
Class: |
525/304 ;
524/533 |
Current CPC
Class: |
C08K 5/353 20130101;
C08K 5/005 20130101; C08K 5/11 20130101; C09K 2323/00 20200801;
C08K 5/005 20130101; C08L 33/12 20130101; C08K 5/11 20130101; C08L
33/12 20130101; C08K 5/353 20130101; C08L 33/12 20130101 |
Class at
Publication: |
525/304 ;
524/533 |
International
Class: |
C08J 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2000 |
JP |
2000-226679 |
Mar 12, 2001 |
JP |
2001-068341 |
Claims
What is claimed is:
1. A methyl methacrylate resin composition comprising a methyl
methacrylate resin and a 2-( 1-arylalkylidene) malonic acid ester
in an amount of about 0.0005 to about 0.1 parts by weight per 100
parts by weight of the methyl methacrylate resin.
2. The methyl methacrylate resin composition according to claim 1,
wherein the 2-(1-arylalkylidene) malonic acid ester is a compound
represented by the formula (1); 3wherein X represents a hydrogen
atom, an alkyl group having 1 to about 6 carbon atoms or an alkoxy
group having 1 to about 6 carbon atoms, and R.sup.1 and R.sup.2
independently represent an alkyl group having 1 to about 6 carbon
atoms.
3. The methyl methacrylate resin composition according to claim 1
or 2, wherein the 2-(1-arylalkylidene) malonic acid ester is
2-(paramethoxybenzylidene)dimethylmalonate.
4. The methyl methacrylate resin composition according to claim 1,
wherein the methyl methacrylate resin composition further comprises
a hindered amine.
5. The methyl methacrylate resin composition according to claim 4,
wherein the hindered amine is a mixture of dodecyl ester and
tetradecyl ester of 2,2,4,4-tetramethyl-21-oxo-7-oxa-3,
20-diazadispyro[5.1.11.2]-heneicosane- -20-propanoic acid.
6. The methyl methacrylate resin composition according to claim 4,
wherein the hindered amine is bis(2,2,6,6-tetramethyl-4-piperidyl)
sebacate.
7. The methyl methacrylate resin composition according to claim 4,
wherein an amount of the hindered amine is not less than about
0.0001 parts by weight and not more than about 0.1 parts by weight
per 100 parts by weight of the methyl methacrylate resin.
8. A molded article made from a methyl methacrylate resin
composition comprising a methyl methacrylate resin and a 2-
(1-arylalkylidene) malonic acid ester in an amount of 0.0005 to 0.1
parts by weight per 100 parts by weight of the methyl methacrylate
resin.
9. The molded article according to claim 8, wherein the methyl
methacrylate resin composition further comprises a hindered
amine.
10. The molded article according to claim 8, wherein a light
transmittance of the molded article is not less than 50% with
respect to light having a wavelength of 400 nm through a 30 cm-long
optical path of the molded article.
11. The molded article according to claim 8, wherein the molded
article is a light guide.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a methyl methacrylate resin
composition and a molded article thereof. More specifically, it
relates to a methyl methacrylate resin composition containing an
ultraviolet absorber, and a molded article thereof.
[0003] 2. Description of the Related Art
[0004] As a conventional method to improve the durability of a
methyl methacrylate resin composition, a method including addition
of an ultraviolet absorber to the composition is known. For
instance, JETI, vol.46, No. 5, p.116-121 (1998) discloses use of a
salicylate, cyano acrylate or benzotriazole compound as an
ultraviolet absorber to be added to methyl methacrylate resins.
[0005] In the case where a methyl methacrylate resin blended with
ultraviolet absorbers conventionally used is molded into an optical
article, however, light transmitted through the optical article may
be somewhat colored presumably due to the power absorbing viewable
light of the ultraviolet absorbers used, hence, the transparency of
the molded optical article may be insufficient. This problem
becomes noticeable particularly when a transmitted optical path
length of the molded optical article is long.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a methyl
methacrylate resin composition exhibiting superior durability
without impairing the transparency inherent to a methyl
methacrylate resin.
[0007] The present inventors made intensive have studied a methyl
methacrylate resin composition exhibiting superior durability
without impairing the transparency inherent to a methyl
methacrylate resin, as a result, found that a methylmethacrylate
resin composition containing a 2-(1-arylalkylidene) malonic acid
ester exhibits superior durability without impairing the
transparency inherent to a methyl methacrylate resin, and have
completed the present invention.
[0008] That is, the present invention provides a methyl
methacrylate resin composition comprising a methyl methacrylate
resin and a 2-(1-arylalkylidene) malonic acid ester in an amount of
about 0.0005 to about 0.1 parts by weight per 100 parts by weight
of the methyl methacrylate resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] The present invention will hereinafter be described in
detail.
[0010] In the present invention, the methyl methacrylate resin is a
polymer comprising not less than about 50% by weight of methyl
methacrylate as a monomer forming the resin. An example of such a
polymer is a polymer comprising not less than about 50% by weight
of poly methyl methacrylate, which is essentially a monopolymer of
methyl methacrylate, or a copolymer comprising methyl methacrylate
and not more than about 50% by weight of an unsaturated monomer,
which is copolymerizable therewith.
[0011] Examples of unsaturated monomers which are copolymerizable
with methyl methacrylate include methacrylic acid esters such as
ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate,
phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl
methacrylate, and 2-hydroxyethyl methacrylate; acrylic acid esters
such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl
acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate,
and 2-hydroxyethyl acrylate; unsaturated acids such as methacrylic
acid and acrylic acid; styrene, .alpha.-methylstyrene,
acrylonitrile, methacrylonitrile, maleic acid anhydride,
phenylmaleimide, and cyclohexylmaleimide. Two or more of these
unsaturated monomers may be used in combination if necessary. The
aforementioned copolymer may contain a glutaric acid anhydride unit
or a glutarimide unit.
[0012] In terms of moldability, alkyl acrylates such as methyl
acrylate are preferred as the unsaturated monomer, which is
copolymerizable with methyl methacrylate. When such an alkyl
acrylate is contained as the unsaturated monomer, the composition
of the monomers used in the copolymer preferably comprises about 80
to about 99.5% by weight of methyl methacrylate and about 0.5 to
about 20% by weight of the alkyl acrylate.
[0013] In terms of its lower water absorption property, styrene is
preferred as the unsaturated monomer, which is copolymerizable with
methyl methacrylate. When styrene is contained as the unsaturated
monomer, the composition of the monomers used in the copolymer
preferably comprises about 60 to about 90% by weight of methyl
methacrylate and about 10 to about 40% by weight of styrene.
[0014] According to the present invention, a 2-(1-arylalkylidene)
malonic acid ester is contained in the methyl methacrylate resin to
provide a methyl methacrylate resin composition having superior
transparency and durability. In terms of durability, an amount of
the 2-(1-arylalkylidene) malonic acid ester is not less than about
0.0005 parts by weight, preferably not less than about 0.003 parts
by weight, more preferably not less than about 0.005 parts by
weight, per 100 parts by weight of the methyl methacrylate resin.
In terms of transparency, the content of the 2-(1-arylalkylidene)
malonic acid ester is not more than about 1 part by weight,
preferably not more than about 0.05 parts by weight, more
preferably not more than about 0.03 parts by weight, per 100 parts
by weight of the methyl methacrylate resin.
[0015] Among 2-(1-arylalkylidene) malonic acid esters, those
represented by the following general formula (1) are preferred in
terms of durability; 1
[0016] wherein X represents a hydrogen atom, an alkyl group having
1 to about 6 carbon atoms or an alkoxy group having 1 to about 6
carbon atoms, and R.sup.1 and R.sup.2 independently represent an
alkyl group having 1 to about 6 carbon atoms.
[0017] In the formula (1), X is preferably a hydrogen atom, an
alkyl group having 1 to about 4 carbon atoms or an alkoxy group
having 1 to about 4 carbon atoms. The alkyl group represented by X
or the alkyl group in the alkoxy group represented by X may be
either in a straight-chain form or in a branched-chain form.
Examples of such alkyl groups include a methyl group, ethyl group,
n-propyl group, i-propyl group, n-butyl group, i-butyl group,
s-butyl group, and t-butyl group. More preferably, X is a methoxy
group.
[0018] Preferably, R.sup.1 and R.sup.2 in the formula (1) are each
an alkyl group having 1 to about 4 carbon atoms. The alkyl group
represented by R.sup.1 or R.sup.2 may be either in a straight-chain
form or in a branched-chain form. Examples of such alkyl groups
include a methyl group, ethyl group, n-propyl group, i-propyl
group, n-butyl group, i-butyl group, s-butyl group, and t-butyl
group. More preferably, R.sup.1 and R.sup.2 are each a methyl
group.
[0019] The composition of the present invention may contain a
hindered amine such as a compound having a
2,2,6,6-tetraalkylpiperidine skeleton for further improved
durability. In this case, the content of such a hindered amine is
usually not less than about 0.0001 parts by weight, preferably not
less than about 0.001 parts by weight, more preferably not less
than about 0.003 parts by weight, per 100 parts by weight of the
methyl methacrylate resin. In terms of cost and transparency, an
amount of the hindered amine is usually not more than about 0.1
parts by weight, preferably not more than about 0.05 parts by
weight, more preferably not more than about 0.03 parts by weight.
The content of the hindered amine per 100 parts by weight of the
2-(1-arylalkylidene) malonic acid ester is usually not more than
about 100 parts by weight, preferably in the range of about 10 to
about 80 parts by weight.
[0020] Examples of such hindered amines include a polycondensate of
dimethyl succinate and
1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpi- peridine,
poly((6-(1,1,3,3-tetramethylbutyl)imino-1,3, 5-triazine -2,4-diyl)
((2,2,6,6-tetramethyl-4-piperidyl)imino)) hexamethylene
((2,2,6,6-tetramethyl- 4-piperidyl)imino,
2-(2,3-di-t-butyl-4-hydroxybenz-
yl)-2-n-bis(1,2,2,6,6-pentamethyl-4-piperidyl) butylmalonic acid,
2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-bis(1,2,2,6,6-pentamethyl-4-piperi-
dyl) butylmalonic acid, a condensate of
N,N'-bis(3-aminopropyl)ethylenedia- mine and
2,4-bis(N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl) amino)-
6-chloro-1,3,5-triazine, bis(2,2,6,6-tetramethyl-4-piperidyl)
sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) succinate, and
compounds represented by the following general formula (2); 2
[0021] wherein Y represents a hydrogen atom, an alkyl group having
1 to about 20 carbon atoms, a carboxyalkyl group having 2 to about
20 carbon atoms, an alkoxyalkyl group having 2 to about 25 carbon
atoms, or an alkoxycarbonylalkyl group having 3 to about 25 carbon
atoms. Two or more of these hindered amines may be used in
combination if necessary. Among them, the compounds represented by
the general formula (2) are preferable.
[0022] In the compounds of the above formula (2), each of the alkyl
group, carboxyalkyl group, two alkyl groups in the alkoxyalkyl
group (the alkyl group in the alkoxy group and the alkyl groups
substituted with the alkoxy group), and two alkyl groups in the
alkoxycarbonylalkyl group (the alkyl group in the alkoxy group and
the alkyl groups substituted with the alkoxycarbonyl group) may be
either in a straight-chain form or a branched-chain form. In the
formula (2), Y is preferably a hydrogen atom or an
alkoxycarbonylalkyl group having about 5 to about 24 carbon atoms.
Particularly, a hydrogen atom or an alkoxycarbonylethyl group is
more preferable as Y. Examples of such alkoxycarbonylethyl groups
include dodecyloxycarbonylethyl group, tetradecyloxycarbonylethyl
group, hexadecyloxycarbonylethyl group, and
octadecyloxycarbonylethyl group.
[0023] The composition of the present invention may contain various
additives if necessary. Examples of such additives include light
diffusing agents or matting agents such as siloxane cross linking
resin particles, styrene cross linking resin particles, acrylic
cross linking resin particles, glass particles, talc, calcium
carbonate, and barium sulfate; antistatic agents such as sodium
alkyl sulfonate, sodium alkylsulfate, stearic acid monoglyceride,
and polyether esteramide; antioxidants such as hindered phenols;
flame-retardants such as phosphoric acid esters; and lubricants
such as palmitic acid and stearyl alcohol. These additives may be
used in combination of two or more of them.
[0024] As a method for preparing the composition of the present
invention, there can be mentioned a method in which the methyl
methacrylate resin, 2-(1-arylalkylidene) malonic acid ester, and,
if necessary, a hindered amine or other additives are melt-kneaded
with use of a single-or twin-screw extruder, or any one of various
kneaders. Alternatively, it is possible to obtain the composition
in a pellet form, a plate form or a like form by mixing a monomer
forming the methyl methacrylate resin or a syrup containing a
partial polymer of the monomer, the 2-(1-arylalkylidene) malonic
acid ester, and, if necessary, a hindered amine or other additives
together to allow bulk polymerization to proceed either batch-wise
or continuously.
[0025] The composition of the present invention can be formed into
various molded articles by molding processes such as extrusion
molding, injection molding, and press molding. Examples of such
molded articles include a signboard, a carport roof, an lighting
cover, a front sheet for vending machines, a showcase, a toy, a
lens, a prism, and a light guide. Among them, optical articles such
as lens, prism, and light guide are preferable.
[0026] When the composition of the present invention is used for
applications as optical articles in particular, a light
transmittance of a molded article made from the composition with
respect to light having a wavelength of 400 nm through a 30 cm-long
optical path is usually not less than about 50%, preferably not
less than about 70%. An average light transmittance of such a
molded article with respect to light in the visible light range
(the wavelength range of about 380 to about 780 nm) is usually not
less than about 75%, preferably not less than about 80%.
[0027] The composition of the present invention can be suitably
used for light guides, in particular, among optical articles. In
recent years, a cold cathode fluorescent lamp exhibiting high
efficiency and high luminance has been developed as a light source
for a backlight of a liquid crystal display device, and with the
development of such a cold cathode fluorescent lamp large-scale
liquid display devices exhibiting increasing luminance are
developed. Under such situations, light guides made from
conventional methyl methacrylate resin compositions sometimes do
not satisfy the requirement of transparency or durability. A light
guide made from the composition of the present invention is
excellent in both transparency and durability and hence can
advantageously be used in a back lighting system incorporating a
cold cathode fluorescent lamp having high luminance without causing
deterioration of its own and of peripheral articles.
[0028] In molding the composition into a light guide, the
composition may be molded into a sheet shape by extrusion molding
using a T die or a roll unit, or may be molded into a sheet shape
or a wedge shape by injection molding or press molding.
Alternatively, the composition in a sheet shape may be prepared by
cast polymerization.
[0029] A light guide made from the composition of the present
invention is suitably used in the backlighting system of a liquid
crystal display device with its screen having a width across
corners measuring not less than about 14 inches, preferably not
less than about 20 inches.
EXAMPLES
[0030] Hereinafter, the present invention will be more specifically
described by way of examples, which should not be construed as
limitative of the present invention.
[0031] The following compounds (A) to (F) were used as a compound
added into a methyl methacrylate resin.
[0032] (A): 2-(paramethoxybenzylidene) dimethylmalonate [a compound
of the formula (1) where X is a methoxy group, which is substituted
at para-position, and R.sup.1 and R.sup.2 are each a methyl group;
produced by Clariant Co. under the trade name: Sanduvor PR-25]
[0033] (B): 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole [produced
by Sumitomo Chemical Co., Ltd. under the trade name: SUMISORB
200]
[0034] (C): 2,4-dihydroxybenzophenone [produced by Sipuro Kasei
Co., Ltd. under the trade name: SEASORB 100]
[0035] (D):
2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-((2H-benzotri-
azole-2-yl) phenol) [produced by Asahi Denka Co., Ltd. under the
trade name: ADEKASUTABU LA31]
[0036] (E): a mixture of dodecyl ester and tetradecyl ester of
2,2,4,4-tetramethyl-21-oxo-7-oxa-3,20-diazadispyro[5.1.11.
2]-heneicosane-20-propanoic acid [a mixture of a compound of the
formula (2) where Y is a dodecyloxycarbonylethyl group and a
compound of the formula (2) where Y is tetradecyloxycarbonylethyl
group; produced by Clariant Co., Ltd. under the trade name:
Hostavin N24]
[0037] (F): bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate [produced
by Chiba-Geigy Co., Ltd. under the trade name: CHINUBIN 770]
[0038] The configuration of an extruder apparatus used in forming
sheets is as follows.
[0039] Extruder: screw diameter=40 mm, single screw, vented
(manufactured by Tanabe Plastics Machinery Co., Ltd.)
[0040] Die: T die, lip width=250 mm, lip gap=6 mm
[0041] Roll: three polishing rolls, vertical type
[0042] The values of the following optical properties were
calculated from the results of measurements of a light
transmittance at a wavelength ranging from 300 to 800 nm at every 5
nm through a 30 cm-long optical path.
[0043] Average light transmittance in the wavelength range of 380
to 780 nm
[0044] x value calculated from the CIE-XYZ color specification
system
[x=X/(X+Y+Z)]
[0045] y value calculated from the CIE-XYZ color specification
system
[y=Y/(X+Y+Z)]
Examples 1 to 5 and Comparative Examples 1 to 4
[0046] A methyl methacrylate resin (a copolymer of methyl
methacrylate and methyl acrylate, having a weight ratio of 96/4 and
a refractive index of 1.49) in an amount of 100 parts by weight,
and a compound, the type and the amount (part(s) by weight) of
which are shown in Table 1, were mixed together in a polyethylene
bag, and then the resulting mixture was melt-kneaded using the
extruder apparatus at an extrusion resin temperature of 250.degree.
C., to form a sheet having a thickness of 3.5 mm and a width of 22
cm. The sheet thus obtained was cut to a size of a width of 7 cm
and a length of 30 cm and mirror-polished at edge faces, to give a
test piece( 7 cm(W).times.30 cm(L).times.3.5 mm(T)).
[0047] The values of the optical properties of each test piece are
shown in Table 1.
[0048] Further, the test pieces of Example 4 and Comparative
Example 1 were tested as to their durability for respective periods
shown in Table 2 using ATLAS-UVCON (manufactured by Toyo Seiki
Seisaku-sho, Ltd.) at 60.degree. C. under the cyclic irradiation
condition of 4 hours' UV irradiation and 4 hours' pure water mist
spraying.
[0049] The values of the optical properties of each test piece
having undergone the test are shown in Table 2.
1 TABLE 1 Average Light light Compound trans- trans- (type: part(s)
mittance mittance in by weight) at 400 nm 380.about.780 nm x value
y value Example 1 (A): 0.0010 80% 84% 0.313 0.319 Example 2 (A):
0.0030 81% 85% 0.312 0.319 Example 3 (A): 0.0070 81% 85% 0.312
0.319 Example 4 (A): 0.0100 80% 84% 0.313 0.319 Example 5 (A):
0.0150 75% 80% 0.314 0.321 Comparative -- 81% 84% 0.313 0.319
example 1 Comparative (B): 0.0100 39% 78% 0.314 0.321 example 2
Comparative (C): 0.0100 36% 78% 0.315 0.323 example 3 Comparative
(D): 0.0100 3% 76% 0.314 0.323 example 4
[0050]
2 TABLE 2 Average Light light trans- trans- mittance mittance in
Test period at 400 nm 380.about.780 nm x value y value Example 4 42
days 78% 82% 0.312 0.320 Comparative 10 days 26% 76% 0.336 0.367
example 1
Examples 6 to 9 and Comparative Examples 5 and 6
[0051] A methyl methacrylate resin (a copolymer of methyl
methacrylate and methyl acrylate, having a weight ratio of 96/4 and
a refractive index of 1.49) in an amount of 100 parts by weight,
and a compound, the type and the amount (part(s) by weight) of
which are shown in Table 3, were mixed together in a polyethylene
bag, and then the resulting mixture was melt-kneaded using the
extruder apparatus at an extrusion resin temperature of 260.degree.
C., to form a sheet having a thickness of 3.5 mm and a width of 22
cm. The sheet thus obtained was cut to a size of a width of 7 cm
and a length of 30 cm and mirror-polished at edge faces, to give a
test piece.
[0052] The values of the optical properties of each test piece are
shown in Table 3.
[0053] Further, these test pieces thus obtained were tested as to
their durability for the period shown in Table 4 using ATLAS-UVCON
(manufactured by Toyo Seiki Seisaku-sho, Ltd.) at 60.degree. C.
under the continuous UV irradiation condition instead of the cyclic
UV irradiation performed in Example 4 and Comparative Example
1.
[0054] The values of the optical properties of each test piece
having undergone the test are shown in Table 4.
3 TABLE 3 Average Light light Compound trans- trans- (type: part(s)
mittance mittance in by weight) at 400 nm 380-780 nm x value y
value Example 6 (A): 0.0080 79% 83% 0.313 0.320 Example 7 (A):
0.0150 79% 83% 0.313 0.320 Example 8 (A): 0.0080 78% 82% 0.313
0.320 (E): 0.0060 Example 9 (A): 0.0150 79% 83% 0.313 0.320 (E):
0.0060 Comparative -- 78% 82% 0.313 0.320 example 5 Comparative
(E): 0.0060 78% 83% 0.313 0.320 example 6
[0055]
4 TABLE 4 Average Light light trans- trans- mittance mittance in
Test period at 400 nm 380-780 x value y value Example 6 6 days 5%
59% 0.383 0.413 Example 7 6 days 46% 78% 0.324 0.340 Example 8 6
days 36% 74% 0.332 0.350 Example 9 6 days 61% 81% 0.318 0.330
Comparative 6 days 0% 43% 0.453 0.455 example 5 Comparative 6 days
6% 35% 0.492 0.464 example 6
Examples 10 to 15 and Comparative Examples 7 to 10
[0056] A methyl methacrylate resin (a copolymer of methyl
methacrylate and styrene, having a weight ratio of 77/23 and a
refractive index of 1.53) in an amount of 100 parts by weight, and
a compound, the type and the amount (part(s) by weight) of which
are shown in Table 5, were mixed together in a polyethylene bag,
and then the resulting mixture was melt-kneaded using the extruder
apparatus at an extrusion resin temperature of 260.degree. C., to
form a sheet having a thickness of 3.5 mm and a width of 22 cm. The
sheet thus obtained was cut to a size of a width of 7 cm and a
length of 30 cm and mirror-polished at edge faces, to give a test
piece.
[0057] The values of the optical properties of each test piece are
shown in Table 5.
[0058] Further, these test pieces thus obtained were tested as to
their durability for the period shown in Table 6 using ATLAS-UVCON
(manufactured by Toyo Seiki Seisaku-sho, Ltd.) at 60.degree. C.
under the condition of continuous UV irradiation.
[0059] The values of the optical properties of each test piece
having undergone the test are shown in Table 6.
5 TABLE 5 Average Light light Compound trans- trans- (type: part(s)
mittance mittance in by weight) at 400 nm 380-780 nm x value y
value Example 10 (A): 0.0160 78% 87% 0.313 0.322 Example 11 (A):
0.0300 73% 84% 0.314 0.322 Example 12 (A): 0.0160 78% 87% 0.313
0.322 (E): 0.0060 Example 13 (A): 0.0300 76% 86% 0.313 0.322 (E):
0.0060 Example 14 (A): 0.0160 74% 84% 0.314 0.322 (E): 0.0120
Example 15 (A): 0.0300 76% 84% 0.315 0.323 (E): 0.0120 Comparative
-- 78% 87% 0.314 0.322 example 7 Comparative (E): 0.0120 77% 86%
0.314 0.323 example 8 Comparative (F): 0.0120 75% 85% 0.314 0.322
example 9 Comparative (B): 0.0300 20% 81% 0.317 0.327 example 10
(E): 0.0120
[0060]
6 TABLE 6 Average Light light trans- trans- mittance mittance in
Test period at 400 nm 380-780 nm x value y value Example 10 6 days
9% 63% 0.398 0.426 Example 11 6 days 21% 68% 0.367 0.393 Example 12
6 days 18% 68% 0.371 0.398 Example 13 6 days 45% 77% 0.336 0.353
Example 14 6 days 21% 69% 0.370 0.395 Example 15 6 days 7% 71%
0.355 0.380 Comparative 6 days 0% 58% 0.428 0.455 example 7
Comparative 6 days 0% 54% 0.422 0.449 example 8 Comparative 6 days
0% 49% 0.453 0.467 example 9 Comparative 6 days 7% 69% 0.366 0.386
example 10
[0061] As described above, the present invention provides a methyl
methacrylate resin composition exhibiting superior transparency and
durability and also provides a useful molded article having these
properties, for example, an optical article such as a light
guide.
* * * * *