JPS6333405A - Methacrylate resin - Google Patents

Abstract

PURPOSE:To provide the titled resin composed of a copolymer of specific amounts of a methacrylic acid ester and a fluoroacrylic acid ester, having low hygroscopicity, excellent heat-resistance, thermal decomposition resistance and transparency and low birefringence and suitable as a base for optical information-recording material. CONSTITUTION:The objective resin having a melt flow rate of preferably 5-100g/10 min at 230 deg.C under 10kg load is produced by copolymerizing (A) 10-99(wt)%, preferably 50-95% one or more monomers selected from methyl methacrylate, cyclohexyl methacrylate and phenyl methacrylate and (B) 1-90%, preferably 5-50% one or more monomers selected from alkyl alpha-fluoroacrylate having 1-4C alkyl, cyclohexyl alpha-fluoroacrylate and phenyl alpha-fluoroacrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a methacrylic resin having a well-balanced property of low moisture absorption, heat resistance, thermal decomposition resistance, transparency and birefringence.

[Conventional technology]

Methacrylic resin, whose main component is methyl methacrylate, not only has excellent transparency and weather resistance, but also has well-balanced properties such as mechanical properties, thermal properties, and moldability. Taking advantage of these characteristics, it is used as a sheet material or molding material in a wide range of applications, including signboards, lighting machine parts, electrical equipment parts, automobile parts, and miscellaneous goods.

On the other hand, as the field of application expands, there are also fields in which the performance requirements for the raw resin are high, and improvements in the following are desired.

One of these is the problem of hygroscopicity. Methacrylic resin has a relatively high hygroscopicity compared to polyolefin resins or polystyrene resins, and this can cause dimensional changes due to moisture absorption, warping of molded products, or long repeated cycles of moisture absorption and drying. There are some fields where there are restrictions on the use of some products due to problems such as the occurrence of cracks.

On the other hand, methacrylic resin has problems such as thermal decomposition at high temperatures (particularly above 280° C.) due to its inherent characteristics, and silver-like defects occur during molding.

Until now, in order to impart low hygroscopicity, a method of copolymerizing phenyl methacrylate (Japanese Unexamined Patent Application Publication No. 61-36307) and a method of copolymerizing cyclohexyl methacrylate (Japanese Unexamined Patent Publication No. 59/1989) have been proposed.
-1518), a method of copolymerizing styrene has been proposed, but the former two have lower strength and the latter have increased birefringence, so they have not been put to practical use as methacrylic resins.

Also, a method of copolymerizing methacrylic acid fluoroalkyl ester, a method of copolymerizing a fluorine-containing monomer (IJJ 1987-227908, JP 60-252610)
However, the former has a low heat distortion temperature and cannot be put to practical use.

The latter all contain fluoroalkyl α-fluoroacrylate as an essential component, and the reality is that they have not been put into practical use because they have problems with adhesion of plating and painting and high cost.

On the other hand, there are methods to improve the heat resistance of methacrylic resin, such as copolymerizing α-methylstyrene and copolymerizing maleic anhydride/styrene. This has become a problem for market expansion. In addition, it is known that copolymerization of acrylic esters is used to improve heat decomposition resistance, but copolymerization of acrylic acid alkyl esters lowers heat resistance, resulting in both heat decomposition resistance and heat resistance. At present, the combination has not been put into practical use.

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the above-mentioned problems and to develop a resin that has low hygroscopicity, excellent heat resistance, and thermal decomposition resistance, and low birefringence.

[Means for solving problems]

In order to achieve the above-mentioned object, the present inventors have conducted intensive studies and found that (A) at least one of the monomers methyl methacrylate, cyclohexyl methacrylate, and phenyl methacrylate has a 10 to 99 concentration, and ( Among α-fluoroacrylic alkyl esters having an alkyl group having 1 to 4 carbon atoms, cyclohexyl α-fluoroacrylate, and phenyl α-fluoroacrylate, at least 1a1 to 90i1 (methacrylate consisting of a co-constitutional union of Sagi-Ken) Friend discovered that a resin composition based on the resin composition had the desired effect, leading to the present invention.

Methyl methacrylate, which constitutes the methacrylic resin of the present invention (component N), improves the weather resistance, mechanical strength, and optical properties inherent to methacrylic resin, and cyclohexyl methacrylate and phenyl methacrylate are essential to methacrylic resin. The amount of methacrylic resin used is 10 to 99M.If it is less than 10% by weight, the original properties of methacrylic resin will be lost. This is because if it is damaged and exceeds 99 smtI4, the heat decomposition resistance will be poor and silver streaks will occur at high temperatures, making it unusable for molding.More preferably 50 to 9 smtI4.

Component (B), which is a constituent component of the present invention, includes α-methyl fluoroacrylate, ethyl a-fluoroacrylate, butyl α-fluoroacrylate, propyl α-fluoroacrylate, and iso-10vinyl fluoroacrylate. ,
α-fluorofluorocyclohexyl acrylate, α-#Lc+phenyl acrylate, etc., which reduce the hygroscopicity of methacrylic resin,
It is intended to improve mechanical strength, thermal decomposition resistance, and heat resistance, and its usage range is 1 to 90 mfl. IN-! If the amount is less than 90, the heat decomposition resistance and mechanical strength will be poor, and if the amount is more than 90, the plating and painting properties will be poor, causing practical problems. More preferably, it is 5 to 5 years old. The fluidity of the resin of the present invention is determined by the melt flow rate specified by ASTM-1238 at 230°C and a load of 10 kg.
1(II) A range of 1 to 100 f/10 minutes is preferred.

When the al value is less than 710 minutes, the molding processability is poor and there is a marked tendency for birefringence to increase, and when it is greater than 1005'710 minutes, the mechanical strength decreases and becomes a practical problem. More preferably it is [15-50f710 minutes. More preferably, it is 1 to 20 f/10 minutes.

However, especially when the methacrylic resin of the present invention is used as an optical information recording medium, (L/D becomes long)
It is preferable that the fluidity is 59,710 minutes or more. If it is less than 5t/10 minutes, the mold transferability tends to be poor and birefringence tends to increase. Regarding the combination of monomers used, it is desirable from the viewpoint of birefringence that the proportion of phenyl group-containing monomer units in the resin is 50 g 1% or less.

The methacrylic resin of the present invention may further contain a small amount of other copolymerizable monomers, if necessary. The amount used is less than 20 g, more preferably less than 101 g. Examples of copolymerizable 4i-mers include acrylic esters such as methyl acrylate and ethyl acrylate; methacrylic esters such as ethyl methacrylate and butyl methacrylate; aromatic vinyl compounds such as styrene and α-methylstyrene 7; Examples include acrylonitrile, maleic anhydride, N-substituted maleimide, and the like. One or more of these can be copolymerized.

Of the methacrylic resin of the present invention! ! ! ! The remaining method may be any known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization.

If necessary, other additives such as an oxidation stabilizer, an ultraviolet absorber, a coloring agent, and a mold release agent may be added to the methacrylic resin composition of the present invention. ] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 5 1000 t of monomer mixture shown in Table 1, 10 t% of azobisin butyronitrile, 20 n-dodecyl mercaptan
? were mixed and poured into a separable flask with an internal volume of 3 tons equipped with a stirrer, and a copolymer of 2-sulfoethyl methacrylic acid sodium salt and methyl methacrylate α22. After dissolving 5 tons of Glauber's salt in 20009 pure water, it was put into a separable flask and heated while stirring, and polymerized at 80°C for 5 hours. The bead-shaped copolymer was washed with water, dehydrated, dried, and then the temperature of the cylinder was raised to 80°C. Vent at 250℃ for 10wH
After shaping under reduced pressure of g and pelletizing, ASTM-1
MP'R (fi dynamic) (230°C, 10
g) was measured, and an injection plate of 2 m/mt×110×1101 was molded at a cylinder temperature of 260°C and a mold temperature of 60°C, and the holes were subjected to evaluation.

Water absorption rate is according to ASTM D570, ASTM D
All heat distortion temperatures were measured in accordance with 684.

Zero birefringence was indicated by the phase difference measured at the center of the specimen using a polarizing microscope POH type manufactured by Nippon Kogaku, using Berecco/Vensator manufactured by Leitz, sodium D line, and a tungsten lamp.

0 total light transmission force and selection price is Mu STM D1003
According to.

O tensile p strength According to ASTM D65B.

The above results are shown in Table 1. This result shows that the methacrylic resin of the present invention can be used for this purpose.

Comparative Example 1 A product was produced and evaluated in exactly the same manner as in Example 1, except that the monomers were 990 t of methyl methacrylate and 10 f of methyl acrylate.

Comparative Example 2 A product was produced and evaluated in the same manner as in Example 1, except that 900f of cyclohexyl t-memethacrylate and 1002 of methyl acrylate were used.

Example 8 It was produced and evaluated in exactly the same manner as in Example 1, except that the amount of n-dodecylmercaptan as a chain transfer agent was changed to Sat. The results are shown in Table-2.

Comparative Example 3 Produced in exactly the same manner as in Example 1 except that the amount of n-dodecyl mercaptan as a chain transfer agent in Example 1 was changed to 12,
It was worth it. The results are shown in Table-2.

Example 9 100 parts of the monomer mixture shown below was added with n as a chain transfer agent.
- Dissolve α3 parts of octyl mercaptan, 11 parts of azobisisobutyronitrile as a polymerization initiator, suspension polymerization dispersant, co-monomer of methyl methacrylate and sodium salt of 2-sulfoethyl methacrylate, total α0005 parts , mixed with 150 parts of pure water in which 5 parts of sodium sulfate [L] was dissolved, and replaced with N in a pressure-resistant polymerization pot with a stirrer. , 12
The bead polymer was kept at 0°C for 15 minutes, cooled, and dried.
After blending 13 parts, the mixture was extruded and pelletized in the same manner as in Example 1, and molded into a mold using a Meiki Tinamelter injection molding machine. , 2 wa, diameter 5QQtm, track spacing 1.6μm, track width CL5μm, track groove depth α3μm was molded under the conditions of cylinder temperature 270°C, mold temperature 70°C, cycle 60 seconds, and release property was determined. was evaluated.

Monomer mixture composition [Results] Mold releasability: The cracks caused by poor peeling after 20 shots did not disappear and were good.

In addition, using an 8-steel 17-65 type injection molding machine, the cylinder temperature was 280°C, and the cycle was 2mt x 110α x
A 110(7) plate was molded, and silver streak defects were visually determined.

〔result〕

No defects were observed in the 20th shot, which was good.

As described above, the resin composition of the present invention can be suitably used as a base material for an optical information recording medium.

〔Effect of the invention〕

The methacrylic resin of the present invention has excellent mechanical properties, optical properties such as transparency and birefringence that are almost comparable to polymethyl memethacrylate, and has excellent low moisture absorption, heat resistance, and heat decomposition resistance. has.

Since the resin composition of the present invention has the above-mentioned properties, it is useful for the following uses.

In the field of optical elements, especially as substrates for optical information recording such as memory disks, lenses (pickup lenses, eyeglass lenses, camera lenses, 7-lens lenses for projectors), and cores or wrappers for optically transmitting fibers. It also has good morphological stability and can be used in a wider range of atmospheres than methacrylic resin.

It is also used for signboards, lighting covers, nameplates, automobile parts, electrical equipment parts, etc.

Claims (1)

[Scope of Claims] 1. (A) at least one of methyl methacrylate, cyclohexyl methacrylate, and phenyl methacrylate monomer 10 to 99% in weight; and (B) α having an alkyl group having 1 to 4 carbon atoms; - A methacrylic resin comprising a copolymer of 1 to 90% by weight of at least one of alkyl fluoroacrylate, cyclohexyl α-fluoroacrylate, and phenyl α-fluoroacrylate. 2. The methacrylic resin according to claim 1, wherein the copolymer has a melt flow rate of 0.1 to 100 g/10 minutes at 230°C and a load of 10 kg. 3. The methacrylic resin according to claim 1, wherein the copolymer has a melt flow rate of 5 to 100 g/10 minutes at 230°C and a load of 10 kg.