JP2003327629A - Methacrylic resin and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a methacrylic resin improved in transparency, heat resistance, chemical resistance and impact resistance in a high productivity without accompanying with a run away polymerization, and also to provide a transparent component, a transparent component for cars and a displaying transparent component each improved in transparency, heat resistance and impact resistance and which are, molded from the methacrylic resin. <P>SOLUTION: The methacrylic resin is prepared by polymerizing a composition containing methyl methacrylate and a specified compound in the presence of a radical initiator together using an organic peroxide compound having a different 10 hrs' half life temperatures. The transparent component, the transparent component for cars and the displaying component are produced by molding the methacrylic resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a methacrylic resin and a transparent member formed from the methacrylic resin. Specifically, the present invention relates to a methacrylic resin obtained by copolymerizing methyl methacrylate (MMA) and a specific compound,
The present invention relates to a transparent member made of the methacrylic resin, a transparent member for a display and a transparent member for an automobile.

[0002]

BACKGROUND OF THE INVENTION Methacrylic resin (PMMA) is
It is widely used as a glazing material for vehicles and buildings, signboards, instrument covers, front panels for flat panel displays (FPDs), light guide panels for LCDs, etc. due to its excellent transparency, lightness, and weather resistance. . However, methacrylic resin has a problem that its heat resistance is lower than that of a polycarbonate resin and the like, and its chemical resistance is inferior, so that its range of use is naturally limited. It has been demanded.

As a method of improving the heat resistance of methacrylic resin, a method of adding cyclohexyl methacrylate to methyl methacrylate and copolymerizing it, a method of adding maleic anhydride and styrene to methyl methacrylate and the like, and the like have been proposed. (JP-A-58-871)
No. 04). However, since these methacrylic resins have a linear structure, no improvement in chemical resistance is observed.

Further, many methods have been proposed for producing a methacrylic resin having a crosslinked structure by copolymerizing methyl methacrylate and acrylates or methacrylate compounds of various polyhydric alcohols. In these production methods, although the heat resistance and chemical resistance of the methacrylic resin are improved, it is difficult to control the polymerization because it tends to suddenly runaway during the polymerization reaction, and it is not widely used at present. .

Further, as a method for improving the impact resistance of the methacrylic resin, a method of stretching the methacrylic resin by a biaxial stretching method or a press stretching method, or a method of adding a rubber component during or after the polymerization is proposed. Has been done. However, the stretching method inevitably causes optical anisotropy in the methacrylic resin, and is not suitable for optical applications, and the applications are limited. On the other hand, in the method of adding the rubber component, the composition and structure of the rubber component, the compounding method,
And the polymer design is done by devising the polymerization method,
There is still a problem in the difference in refractive index and compatibility between the methacrylic resin that is the matrix and the rubber component, and compatibility is insufficient, and improvement in impact resistance is also insufficient.

By the way, a head / tail lamp lens,
Inorganic glass has been widely used for automotive transparent parts such as lamp covers, roof windows, rear quarter windows, front / rear panels, and visors because of the physical properties of the members and the technical advantages of manufacturing the parts. However, from the viewpoints of energy saving and environmental protection, the weight of automobiles is reduced, and the design around the lamps and the window materials is designed freely in response to the diversification of the body design (appearance design and aerodynamics). With regard to lenses, there are strong demands from automobile manufacturers to improve light distribution performance such as illumination range and brightness, to avoid the risk of collision destruction shapes, and due to JASO standard revisions, front windows and side windows ( Transparent resins have been rapidly used for members of transparent parts other than some.

As the resin, methacrylic resin (PMM
A), polycarbonate resin (PC), methacrylic and styrene copolymer resin (MS), polystyrene (PS),
Copolymer resin (SAN) of styrene and acrylonitrile,
Examples thereof include vinyl chloride resin and the like, but PMMA and PC are particularly used. This is PMMA
Is excellent in transparency, weather resistance, balance of mechanical properties, and moldability, and PC is excellent in transparency, heat resistance, water absorption rate, and impact resistance.

However, PMMA has insufficient heat resistance and impact resistance, and PC has insufficient rigidity, surface hardness, weather resistance and chemical resistance. For this reason, the use parts (parts) of these resins are naturally limited, and it is strongly desired to improve the physical properties of the resins. For example, when PMMA is used as a lamp lens, it is necessary to improve heat resistance in order to prevent the lens shape from being deformed due to thermal deformation, but the mainstream of the technology is a monomer having a strong polarity and a bulky structure, and MMA. Is to copolymerize with. Examples of such a technique include copolymerization of MMA with an N-substituted maleimide such as phenylmaleimide or cyclohexylmaleimide, phenylmethacrylate, or an alicyclic methacrylic acid ester, or a monomer such as aromatic vinyl. Also, PMM
In order to improve the impact resistance of A, a technique in which a rubber component is added to MMA and graft polymerization is known is known.

For PC, it is necessary to increase the surface hardness to improve scratch resistance in order to prevent scratches. The mainstream of this technique is so-called hard coating, which forms a highly crosslinked structure on the PC surface to impart resistance to external force. As such a technique, a method of applying an organic silane composition liquid and curing it with heat, a method of applying a polyfunctional acrylate composition liquid and curing it with ultraviolet rays or electron beams, and a sputtering method of a metal or a metal oxide. And so on. Since the hard coating can improve the weather resistance and heat resistance of the substrate at the same time, this technique is widely practiced in that sense as well.

Among the transparent parts for automobiles, the requirement for the shape thereof is particularly strong around the lamp which is one of the external shapes of the automobile. There are various geometric requirements around the lamps of automobiles, such as a more curved shape to reduce air resistance, a smaller occupied volume, and a design that attracts user's attention. This requirement is the same for the lamp lens, and the physical property particularly desired for the member of the lamp lens is heat resistance. Here, the conventional heat-resistant grade PMMA has improved heat resistance as compared with ordinary PMMA which is a linear polymer, but other physical properties such as reduced impact resistance are sacrificed. Further, the polymerization becomes runaway, and the control of the polymerization control becomes strict, so that it is not an advantageous technique in terms of molding processing.

On the other hand, the PC is used around the lamp after undergoing a hard coating process. However, it is desired to establish a more precise coating technology in order to deal with a complicated shape around the lamp. PMMA and PC are also used as members of some window parts such as roofs, rear quarters, and sides, but their rigidity is insufficient, so the base material inevitably becomes thicker and lighter. It goes in the opposite direction. In addition, it is not possible to meet various demands on the appearance and functions of automobiles by automobile users, such as application to fixed windows in which the base material is fixed with a metal frame. Since the rigidity depends largely on the physical properties of the resin, improving the physical properties is also a major issue.

[0012] By the way, the projector has been conventionally used for presentations at conferences in companies, theaters, cultural halls, event venues, etc., but in recent years the demand for homes and individuals has increased.
Recent projectors are not only used as enlargement and projection devices for images such as overhead projectors or slide projectors, but also used as electronic displays such as rear projection TVs. In particular, the rear projection TV is expected to be increasingly used as a home multimedia home PC, a multi-screen incorporating a game, or an in-vehicle display such as a data display of an automobile meter and a car navigation.

Generally, inorganic glass is used as a member of transparent parts such as a projection lens and a projection screen which are optical systems of a rear projection TV. Although it is not an optical system, it also enhances the visibility of the display and protects the display surface of the display in every sense, such as rear projection TV or P
In the case of a transparent component such as a DP, which is a front plate, the mainstream is also inorganic glass.

Several problems can be pointed out for such a transparent component. One is to reduce the weight of the screen member, which should avoid an increase in weight due to the increase in size of the rear projection screen. Second, there is a demand for safety in terms of safety, such as crack resistance or safety at the time of breakage. And third is the free design of the screen shape from the pursuit of eye-catching display design.

Therefore, it is required to use a glass substitute resin as the transparent member. Currently, as a projection lens for rear projection TV, heat-resistant grade P
Although MMA is used in part, heat resistance is still insufficient and improvement is required. Further, insufficient rigidity is also a serious problem, and is insufficient as a member such as a screen.

[0016]

An object of the present invention is to provide a methacrylic resin having improved heat resistance, chemical resistance and impact resistance. Another object of the present invention is to provide a methacrylic resin that can be produced without causing a runaway polymerization reaction during polymerization. A further object of the present invention is to provide a transparent member made of the methacrylic resin of the present invention, an automotive transparent member and a display transparent member.

[0017]

SUMMARY OF THE INVENTION A methacrylic resin of the present invention comprises a composition containing 100 parts by weight of methyl methacrylate and 5 to 50 parts by weight of a compound represented by the following general formula (I): Copolymerized in the presence of a radical initiator in which at least one of the organic peroxide having an epoch temperature of 50 to 75 ° C and (b) an organic peroxide having a half-life of 10 hours of 95 to 120 ° C is used in combination. It is characterized by

[0018]

[Chemical 2]

(In the formula (I), R represents a hydrogen atom or a methyl group) Such a methacrylic resin of the present invention has a copolymerization temperature of
It is also preferably 40 to 170 ° C. The transparent member of the present invention,
The transparent member for automobiles and the transparent member for displays are formed by molding the methacrylic resin of the present invention.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be specifically described below. Methacrylic Resin The methacrylic resin of the present invention is obtained by copolymerizing a composition containing methyl methacrylate and a compound represented by the following general formula (I) in the presence of a radical initiator.

[0021]

[Chemical 3]

(In the formula (I), R represents a hydrogen atom or a methyl group) The compound represented by the general formula (I) (compound (I)) is
Specifically, N- (3-isopropenyl-α, α-dimethylbenzyl) -2-methacryloyloxyethyl carbamate or N- (3-isopropenyl-α, α
-Dimethylbenzyl) -1-methacryloyloxypropan-2-ylcarbamate.

The compound (I) is characterized in that the polymerization with methyl methacrylate proceeds extremely mildly and leads to three-dimensional crosslinking. This is because the activity of the isopropenyl group in the molecule is relatively mild and the reaction rate is slow, and because it is involved in the polymerization while controlling the reaction of the methacryl group, it is considered that the polymerization and curing as a whole proceed in a random and mild manner. .

In the present invention, as the radical initiator,
(A) an organic peroxide having a 10-hour half-life temperature of 50 to 75 ° C.,
(B) At least one of the organic peroxides having a 10-hour half-life temperature of 95 to 120 ° C. is used in combination. (A) As the organic peroxide having a 10-hour half-life temperature of 50 to 75 ° C., 2,4-dichlorobenzoyl peroxide, t-
Butyl peroxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, succinic acid peroxide, acetyl peroxide, t-butylperoxy-2- Examples thereof include ethyl hexanoate, m-toluoyl peroxide, benzoyl peroxide and the like.

(B) Organic peroxides having a 10-hour half-life temperature of 95 to 120 ° C. include t-butylperoxymaleic acid, t-butylperoxylaurate, t-butylperoxy-3, 5,5-trimethylhexanoate, cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-
2,5-di (benzoylperoxy) hexane, 2,2
-Bis (t-butylperoxy) octane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate,
n-Butyl-4,4-bis (t-butylperoxy) valerate, di-t-butyl-diperoxyisophthalate, methyl ethyl ketone peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di Examples include (t-butylperoxy) hexane and t-butylcumyl peroxide.

(A) Organic peroxide (organic peroxide (a)) having a 10-hour half-life temperature of 50 to 75 ° C., and (b) organic peroxide having a 10-hour half-life temperature of 95 to 120 ° C. (organic peroxide). The proportion of the peroxide (b)) used is preferably organic peroxide (a) ≧ organic peroxide (b). Further, it is more preferable that the organized oxide (b) has a 10-hour half-life temperature of 95 to 110 ° C. When the organic peroxide (a) and the organic peroxide (b) are used together as a radical initiator in the copolymerization, the organic peroxide (a) having a 10-hour half-life temperature of 50 to 75 ° C first acts. It is considered that the polymerization is initiated, the initial polymerization proceeds, and at a certain stage, the organic peroxide (b) having a 10-hour half-life temperature of 95 to 120 ° C acts to further promote the polymerization and the crosslinking.
Therefore, as a radical initiator, organic peroxide (a)
By using the organic peroxide and the organic peroxide (b) together, the copolymerization reaction proceeds more mildly, and the runaway of the polymerization reaction can be easily avoided.

The amount of the radical initiator used is such that the total amount of the radical initiator is 0.01 to 5 with respect to the composition to be copolymerized.
It is desirable that the amount be in the range of% by weight. In producing the methacrylic resin of the present invention, an antioxidant or an antistatic agent may be added to the composition to be copolymerized for the purpose of preventing coloration and antistatic. Moreover, you may add other polymerizable monomers suitably.

The composition thus prepared is degassed and prepared for copolymerization. The copolymerization may be carried out by any method, for example, in cast polymerization, it can be carried out as follows. A mold releasing agent may or may not be used in the casting polymerization. Casting polymerization is a polymerization method in which the previously prepared composition is injected into the space of a mold forming a resin molded body having a desired shape, heat polymerization is performed, and then the mold is removed to obtain a molded body. Here, a gasket is provided for the purpose of enclosing the composition in the mold, following the mold by polymerization-curing shrinkage of the composition, and the like.

In order to obtain a flat-plate resin molded body, it is common to select a mold made of inorganic glass or stainless steel and use a gasket or vinyl chloride or silicone resin sheet or tube as a gasket. The heating temperature for the copolymerization in the present invention depends on the types and the amounts of the composition and the radical agent used, but it is usually preferably 40 to 170 ° C. More specifically, the initial temperature of heating is 40 ° C or higher, preferably
50 ° C or higher, more preferably 60 ° C or higher, and the temperature at the end of heating is 170 ° C or lower, preferably 150 ° C or lower, more preferably 130 ° C or lower. It is desirable to appropriately select the holding time and the temperature rising rate, and set the temperature conditions to raise the temperature stepwise. The polymerization time is usually 4 though it depends on the heating temperature.
It is desirable that the time is about 7 to 7 hours, preferably about 5 to 7 hours.

The methacrylic resin of the present invention has excellent transparency and a glass transition temperature (Tg) of usually 120 ° C. or higher, preferably 125 ° C. or higher, more preferably 130 ° C. or higher, and has excellent heat resistance. The flexural modulus of the methacrylic resin of the present invention is usually 3.2 GPa or more, preferably 3.6 GP.
It is at least a, more preferably at least 4.0 GPa. Further, in the impact resistance test (falling ball test) described later, the height at which the resin plate does not crack is 50 cm or less in the case of the usual methacrylic resin, whereas it is usually 50 cm in the case of the methacrylic resin of the present invention.
The above is preferably 60 cm or more, more preferably 65 cm or more, particularly preferably 70 cm or more, and excellent impact resistance is exhibited. Furthermore, the methacrylic resin of the present invention is resistant to alteration by organic solvents such as acetone, toluene, xylene, and isopropanol, and alkaline solvents such as sodium hydroxide solution, and exhibits excellent chemical resistance.

Also, the methacrylic resin of the present invention is easy to control the temperature of the polymerization and is excellent in molding processability because there is no concern that the polymerization will proceed mildly and the runaway reaction will occur in the reaction side of the polymerization. Furthermore, since the obtained methacrylic resin is optically and mechanically isotropic, the physical properties within the solid are uniform, and the surface state of the resin molded product is extremely good.

As described above, the methacrylic resin of the present invention has markedly improved physical properties such as heat resistance, impact resistance, surface hardness, rigidity and chemical resistance without impairing the original transparency of the methacrylic resin. This methacrylic resin is widely used as a glazing material, various covers, signboards, front plates for displays such as PDPs, or screen substrates for projectors, etc.
The A resin plate can be manufactured with high productivity. That is, the methacrylic resin of the present invention can be suitably used as various transparent members, particularly automotive transparent members and display transparent members. As a transparent member for automobiles, it can be preferably used around lamps that require high heat resistance and window materials that require high impact resistance.

Applications Since the methacrylic resin of the present invention described above is excellent in transparency, heat resistance, chemical resistance and impact resistance, it can be used not only as a substitute for conventional methacrylic resins but also in the existing ones. It can also be used as a substitute for polycarbonate resin, and is widely used as, for example, glazing materials, various covers, signboards, display front plates such as PDPs, screen substrates such as projectors, liquid crystal plastic substrates, organic EL substrates, and touch panel substrates. Available.

In particular, since the methacrylic resin of the present invention has the above-mentioned excellent properties, it can be suitably used as various transparent members, in particular, it can be suitably used as transparent members for automobiles, transparent members for displays and the like. it can. Examples of transparent members for automobiles include molded articles for automobiles such as head / tail lamp lenses, lamp covers, roof windows, rear quarter windows, front / rear panels and visors.

As the transparent member for a display, an optical member such as a projection lens or a projection screen,
Examples include a front plate that protects the display surface of the display. Specifically, molded parts for projectors or rear projectors (diffusion type rear projection screen, lenticular screen, spherical lens type /
Orthogonal lenticular lens array screen, diffusion type with Fresnel lens / lenticular screen with Fresnel lens, projection lens for rear projection TV, front plate for rear projection TV, etc.), PDP
Front plate for use.

[0036]

According to the present invention, a methacrylic resin having excellent transparency, heat resistance, chemical resistance and impact resistance can be provided with good productivity without causing a runaway polymerization reaction. Further, according to the present invention, it is possible to provide a transparent member formed of the methacrylic resin of the present invention and having excellent properties such as transparency, heat resistance and impact resistance, a transparent member for automobiles and a transparent member for displays. it can.

[0037]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. In the following examples and comparative examples, parts by weight represent g. <Evaluation method> The physical properties of the resin were evaluated as follows.

[0038]   ・ Ease of polymerization: Runaway reaction (Wakame phenomenon: The surface of the resin is disturbed due to the appearance of a bark.                 The presence and degree of elephant) were visually confirmed according to the following criteria.                      ○ Does not happen                      △ Partially occurs                      × Occurs on the entire surface   -Heat resistance: Tg was measured with a TMA analyzer manufactured by Rigaku Corporation.

[0039]   ・ Impact resistance: A resin ball with a weight of 114 g is dropped onto a resin plate with a thickness of 2 mm                 It was compared with the height that does not crack.   -Surface hardness: The pencil hardness was measured by the JIS K5401 method.   -Rigidity: Flexural modulus was measured by the JIS K6911 method.   ・ Chemical resistance: JIS K7114 method, acetone, IPA (isopropanol),                 Toluene, 10% NaOH, each according to the following criteria                 It was evaluated visually.

○ No abnormalities were observed △ Crack × Dissolution (Preparation Example 1) 3-isopropenyl-α, α was placed in a four-necked flask equipped with a stirrer, a thermometer, a drying tube and a dropping funnel.
-Dimethylbenzyl isocyanate 242.8g, dibutyltin dilaurate 0.12g was charged, the internal temperature 45 ~
2-hydroxyethyl methacrylate 157.
0 g was added dropwise over 2 hours. Then, the compound (1) was obtained by performing an aging reaction at 50 ° C. for 8 hours.

Preparation Example 2 3-isopropenyl-α, α-dimethylbenzyl isocyanate 23 was placed in a 4-necked flask equipped with a stirrer, a thermometer, a drying tube and a dropping funnel.
3.0 g and 0.12 g of dibutyltin dilaurate were charged, and 167.0 g of 2-methyl-1-methacryloyloxyethanol was added dropwise at an internal temperature of 45 to 50 ° C. over 2 hours. Then, aging reaction was performed at 50 ° C. for 8 hours to obtain a compound (2).

[0042]

Example 1 A mixture of 100 parts by weight of MMA and 10 parts by weight of compound (1) synthesized by the same formulation as shown in Preparation Example 1,
0.3 parts by weight of benzoyl peroxide and t-butylperoxy-3,5,5-trimethylhexanoate 0.
2 parts by weight was added and mixed well, and then degassed to prepare for polymerization. Then, this composition was poured into a casting polymerization mold having a vinyl chloride gasket and having a clearance of 1 mm, and the mixture was kept at 60 ° C. for 2 hours at a constant temperature.
Polymerization was carried out by raising the temperature to 30 ° C. over 2 hours and then maintaining the temperature at 130 ° C. for 1 hour at a constant temperature. No abnormality was observed during the polymerization, and then the resin plate was removed from the mold to obtain a transparent resin plate having a good surface condition.

[0043]

Example 2 A mixture of 100 parts by weight of MMA and 25 parts by weight of compound (1) synthesized by the same formulation as shown in Preparation Example 1,
t-Butylperoxy-2-ethylhexanoate 0.
3 parts by weight and 0.2 parts by weight of t-butylperoxy-3,5,5-trimethylhexanoate were added and mixed well,
It was then degassed and prepared for polymerization. Then, this composition was poured into the same mold for casting polymerization as shown in Example 1,
After maintaining the temperature at 0 ℃ for 2 hours, 70 ℃ to 130 ℃
Up to 2 hours and then maintained at 130 ° C. for 1 hour at a constant temperature to carry out polymerization. No abnormality was observed during the polymerization, and then the resin plate was removed from the mold to obtain a transparent resin plate having a good surface condition.

[0044]

Example 3 Polymerization was carried out in the same manner as in Example 2 except that 25 parts by weight of the compound (1) was changed to 45 parts by weight. No abnormality was observed during the polymerization, and then the resin plate was removed from the mold to obtain a transparent resin plate having a good surface condition.

[0045]

Example 4 A mixture of 100 parts by weight of MMA and 25 parts by weight of compound (2) synthesized by the same formulation as in Preparation Example 2,
0.3 parts by weight of benzoyl peroxide and 0.2 parts by weight of t-butyl peroxylaurate were added and mixed well, and then degassed to prepare for polymerization. Then, this composition was poured into the same mold for casting polymerization as shown in Example 1 and kept at 60 ° C. for 2 hours at a constant temperature.
The temperature was raised to 10 ° C. over 2 hours, then 110 ° C. for 1 hour, and then 130 ° C. for 1 hour to carry out polymerization while maintaining a constant temperature. No abnormality was observed during the polymerization, and then the resin plate was removed from the mold to obtain a transparent resin plate having a good surface condition.

[0046]

Example 5 A mixture of 100 parts by weight of MMA and 25 parts by weight of the compound (1) synthesized by the same formulation as in Preparation Example 1 was added.
-Butylperoxy-2-ethylhexanoate 0.3
By weight, t-butylperoxy-3,5,5-trimethylhexanoate (0.2 parts by weight) was added and mixed well, and then degassed to prepare for polymerization. Then, this composition was poured into a spectacle lens polymerization mold having an elastomer gasket and kept at 70 ° C. for 2 hours at a constant temperature.
Temperature rise from 0 ℃ to 130 ℃ over 2 hours, then 130
Polymerization was carried out at a constant temperature of 1 ° C for 1 hour. No abnormalities were observed during the polymerization, after which it was released from the mold and was transparent, with a refractive index nd
= 1.55, Abbe number νd = 43, and Tg = 150 ° C. A lens-shaped molded body was obtained.

The obtained molded product was also very excellent in scratch resistance and impact resistance, and both were evaluated as ◯.
The physical properties of the obtained lens-shaped molded product were measured and evaluated as follows. -Refractive index, Abbe number: 20 using the Pulfrich refractometer
It was measured at ° C. -Scratch resistance: The surface of the resin molded body was rubbed with # 0000 steel wool to examine the scratch resistance of the surface, and judged as follows.

◯: No scratches even when rubbed hard Δ: Slight scratches when rubbed strongly ×: Scratches even when rubbed weakly · Impact resistance: Height 127 cm at center of molded lens
From the above, 16 g of steel balls were dropped and the cracking resistance was examined, and the judgment was made as follows.

◯: No crack △: No cracks, but small cracks ×: cracked

[0050]

Comparative Example 1 0.5 part by weight of benzoyl peroxide was added to 100 parts by weight of MMA and mixed well, and then degassed to prepare for polymerization. Then, this composition was poured into the same mold for casting polymerization as shown in Example 1, kept at a constant temperature at 60 ° C. for 2 hours, then heated from 60 ° C. to 90 ° C. over 1 hour, and then 90 ° C. 1 hour at 120 ° C for 1 hour
Polymerization was carried out while maintaining a constant temperature for each time. No abnormality was observed during the polymerization, and then the resin plate was removed from the mold to obtain a transparent resin plate having a good surface condition.

[0051]

Comparative Example 2 In a mixture of 100 parts by weight of MMA and 25 parts by weight of EGDM (ethylene glycol dimethacrylate),
0.5 parts by weight of benzoyl peroxide was added and mixed well, and then degassed to prepare for polymerization. Then, this composition was poured into the same mold for casting polymerization as shown in Example 1 and kept at a constant temperature for 2 hours at 50 ° C. and then for 1 hour at 70 ° C. Polymerization was carried out by raising the temperature over a period of time and then maintaining the temperature at 90 ° C. for 1 hour and then at 130 ° C. for 1 hour. During the polymerization, the reaction was runaway at around 70 ° C. and a wakame phenomenon occurred. Then, the mold was removed to obtain a transparent resin plate, but the surface condition was not good.

Table 1 shows the composition ratios of the monomers and the evaluation of the physical properties of the resins in Examples 1 to 4 and Comparative Examples 1 and 2.

[0053]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // (C08F 220/14 C08F 212: 34 212: 34) B29K 33:04 B29K 33:04 C08L 33:10 C08L 33:10 (31) Priority claim number Japanese Patent Application 2002-59248 (P2002-59248) (32) Priority date March 5, 2002 (2002.3.5) (33) Priority claim country Japan (JP (72) Inventor Masahiro Shioji Mitsui Chemicals Co., Ltd. 580-32 Nagaura, Sodegaura-shi, Chiba F-term within the company (reference) 4F071 AA33 AA33X AF02 AF14 AF23 AF25 AF30 AF31 AH07 AH19 BA09 BB01 BC07 4F204 AA21 AB04 AH17 AH81 AR06 EA01 EA04 EB01 EF01 EF02 EK26 4J015 BA04 BA06 BA07 BA10 4J100 AL03P AL74Q BA39Q BC43Q CA04 DA22 DA25 DA36 DA48 DA49 DA62 DA63 DA64 FA03 FA17 FA28 JA32 JA33 JA50

Claims (5)

[Claims] 1. A composition containing 100 parts by weight of methyl methacrylate and 5 to 50 parts by weight of a compound represented by the following general formula (I), (a) an organic compound having a 10-hour half-life temperature of 50 to 75 ° C. Methacrylic obtained by copolymerizing a peroxide and (b) an organic peroxide having a 10-hour half-life temperature of 95 to 120 ° C. in the presence of a radical initiator in combination with at least one of them. Resin. [Chemical 1] (In the formula (I), R represents a hydrogen atom or a methyl group) 2. The copolymerization temperature is 40 to 170 ° C.
The methacrylic resin according to. 3. A transparent member obtained by molding the methacrylic resin according to claim 1 or 2. 4. A transparent member for automobiles, which is formed by molding the methacrylic resin according to claim 1 or 2. 5. A transparent member for a display formed by molding the methacrylic resin according to claim 1 or 2.