JP2003292714A - Solvent-resistant resin composition and vehicular lamp lens using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solvent-resistant resin composition excellent in molding processability without impairing the original transparency and weather resistance of an acrylic resin, and a vehicle lamp lens using the same. SOLUTION: This is a resin composition obtained by melting and mixing 40 to 80 parts by weight of the following copolymer (A) and 60 to 20 parts by weight of a copolymer (B), and a lamp lens injection-molded therewith. Copolymer (A) MMA (85 to 95 wt%) / MA (5 to 15 wt%)
%), 2 copolymer copolymer (B) having a weight average molecular weight of 80,000 to 160,000 MMA (70 to 80 wt%) / ST (12 to 18 wt%)
%) / MAH (8 to 12 wt%), weight average molecular weight 12
~ 160,000 terpolymer

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to tail lamps and stop lamps used as lamp lenses for vehicles.

[0002]

2. Description of the Related Art Acrylic resins, which are excellent in transparency and weather resistance, are used in lamp lenses for vehicles, but there is a problem that solvent cracks are likely to occur due to organic solvents contained in window washer liquid, wax remover and the like. In order to improve this solvent resistance, improvement of lens materials has been studied, and a method using a high molecular weight methacrylate resin (Japanese Patent Publication No. 5-82001) and a method using an acrylic graft rubber (JP-A-7-28262). ) Etc. have been proposed. However, when the polymer has a high molecular weight, the molding fluidity is lowered, so that the molding processability is poor, and when the graft rubber is used, the transparency is lowered and the original properties of the acrylic resin are impaired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide excellent resistance to solvent cracking, high fluidity and excellent moldability without impairing the transparency and weather resistance which are the original properties of acrylic resin. It is intended to provide a solvent-based resin composition and a vehicle lamp lens using the same.

[0004]

Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have conducted extensive studies and found that a resin composition obtained by melt-kneading a specific copolymer containing methyl methacrylate as a main component was obtained. The present invention has been completed and the present invention has been completed. That is, the present invention includes "1" 40 to 80 parts by weight of the copolymer (A) and the copolymer (B) 60 to 20 shown below.
A resin composition obtained by melting and mixing parts by weight according to JIS
A resin composition having a standard K7210, a melt mass flow rate of 1.6 to 3.0 under condition N and a solvent resistance index (K) of more than 300. However, solvent resistance index (K) = break time (seconds) when ethanol is applied under a load bending stress of 40 megapascals

Copolymer (A) Methyl methacrylate unit 85-95 wt% Methyl acrylate unit 5-15 wt% Weight average molecular weight 80-160,000 Copolymer (B) Methyl methacrylate unit 70-80 wt% Styrene unit 12- 18 wt% maleic anhydride unit 8 to 12 wt% weight average molecular weight 12 to 160,000 "2" The solvent resistant resin composition according to the above "1", wherein the weather resistance index (W) is less than 2.0. However, weather resistance index (W) = Sunshear weather meter Difference between yellowing degree after irradiation for 1000 hours and yellowing degree of unirradiated product “3” The solvent resistant resin composition according to the above “1” to “2” Lamp lens for vehicles obtained by injection molding. Regarding The present invention will be described in detail below.

The copolymer (A) used in the present invention is
The amount of methyl methacrylate used is 85w, which is an acrylic binary copolymer composed of 85 to 95 wt% of methyl methacrylate unit and 5 to 15 wt% of methyl acrylate unit.
If it is less than t%, the heat distortion resistance is poor, and if it exceeds 95 wt%, the molding processability is not substantially improved. The weight average molecular weight of the copolymer is in the range of 80 to 160,000, and when it is less than 80,000, it is excessively weakened and the mechanical strength is poor, and when it exceeds 160,000, the molding fluidity is poor and the object of the present invention is achieved. Becomes substantially difficult, and a more preferable range is 110,000 to 150,000.

The copolymer (B) used in the present invention is
Methyl methacrylate unit 70-80 wt%, styrene unit 12-18 wt%, and maleic anhydride unit 8-12 wt%
% Is less than 70 wt% of methyl methacrylate, which is an acrylic terpolymer and is poor in thermal decomposition resistance and transparency, and the total amount of styrene and maleic anhydride used is 2%.
It is 0 to 30%, and if it is less than 20 wt%, neither solvent resistance nor heat distortion resistance is substantially improved, while if it exceeds 30 wt%, mechanical strength characteristics are poor, which is not preferable. The ratio of styrene and maleic anhydride used is 1.4 to 1.8.
(Parts by weight of styrene to 1 part by weight of maleic anhydride)
Is preferable, and outside the range, the copolymerizability and the transparency of the copolymer are poor, which is not preferable. The weight average molecular weight of the copolymer (apparent weight average molecular weight in terms of polymethylmethacrylate by GPC method) is in the range of 120 to 160,000, and if it is out of the range, fluidity and mechanical strength properties are poor.

The solvent resistant resin composition of the present invention is a resin composition obtained by melt-mixing the above-mentioned copolymer (A) and copolymer (B) by a usual method. The amount used in the resin composition is a copolymer (40 to 80 parts by weight of A and 20 to 60 parts by weight of copolymer (B) (total of A + B is 100 parts by weight), use of copolymer (A) The reason why the amount is 40 to 80 parts by weight is to impart molding fluidity and weather resistance. If the amount exceeds 80 parts by weight, the heat distortion resistance is inferior, while the reason for using the copolymer (B) in an amount of 20 to 60 parts by weight is to impart solvent resistance and heat resistance.

When the amount used is less than 20 parts by weight, the effect of improving solvent resistance is small, and when it exceeds 60 parts by weight, fluidity and
Poor mechanical strength characteristics. Regarding the weather resistance of the solvent-resistant resin composition of the present invention, the solvent resistance index W (difference in yellowing degree before and after irradiation for 1000 hours of sunshine weather meter) is less than 2.0, and the original important characteristics of the acrylic resin are maintained. There is. 2.
If it exceeds 0, the weather resistance is inferior, which naturally causes a problem as a vehicle body visual recognition device. In order to substantially maintain this important characteristic without impairing it, the methyl methacrylate unit ratio in the resin composition is preferably 75 wt% or more.

The vehicle lamp lens of the present invention can be obtained by injection-molding the above solvent-resistant resin composition. The injection-molding method is not particularly limited, and known ones can be used, and the injection-molding temperature is from 200 to 200. It is in the range of 260 ° C. The copolymers (A) and (B) of the present invention can be produced by applying known polymerization methods such as suspension polymerization, solution polymerization and bulk polymerization, and are not particularly limited. If desired, known colorants, stabilizers such as UV absorbers and antioxidants, and various additives may be used in the vehicle lamp lens of the present invention.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to Examples and Comparative Examples. All parts used in the examples are parts by weight and all percentages are percentages by weight. In the following examples, physical properties were measured by the following methods. 1. A test piece of 12.7 * 127 * 3 mm was cut out from a solvent-resistant injection-molded plate, annealed at 80 ° C. for 30 minutes, left to cool in a desiccator, applied the cantilever method, and fixed one end of the test piece, A position 5 cm away from the fulcrum is used as a fulcrum, and a load is applied to the other end 5 cm away from the fulcrum. A 5 mm long and 5 mm wide filter paper is placed on the center of the upper surface of the test piece on the fulcrum, and ethanol is dripped onto the filter paper with a microsyringe. Apply, temperature 2
The breaking time (seconds) at a bending stress of 40 megapascals was measured at 5 ° C. and a relative humidity of 50% and used as an index (K) of solvent resistance.

2. Weight average molecular weight of polymer / lens resin Gel permeation chromatography (GPC)
Equipment obtained under the following conditions at HLC-812 manufactured by Tosoh Corporation
0 + SC-8020, Column Tosoh TSK Super HH
-M (2 pieces) Super H2500 (1 piece) series, detector RI, solvent THF, flow rate 0.3 ml / min, sample 10 mg
/ 20ml THF solution 10μl device injection, monodisperse PMM
The weight average molecular weight was determined by a calibration curve using A (manufactured by GL Sciences) as a standard sample.

3. Melt mass flow rate (hereinafter MFR
It is abbreviated to) JIS standard K7210 compliant, test condition N 4. Tensile strength According to ASTM standard D638, specimen thickness 1/8 inch 5. Yellowing degree Conforms to JIS standard K7105, colorimetric condition (b), test piece thickness 3 mm 6. It was determined by the weather resistance Sunshine weather meter method under the following conditions.

The test apparatus is WE-S manufactured by Suga Test Instruments Co., Ltd.
UN-DC, BP temperature 63 ° C., water 12 minutes / drying 60 minutes cycle, continuous irradiation for 1000 hours (arc carbon is 50
Exchanged in time). This sample was compared and observed with a blank sample stored in a dark desiccator, and the absolute value of the yellowing difference was used as a weather resistance index. 7. Heat distortion temperature (hereinafter abbreviated as HDT) Complies with ASTM standard D648

[0015]

Example 1 Production of Copolymer (A) In a 60-liter polymerization vessel, 90 parts of methyl methacrylate,
Methyl acrylate 10 parts, lauroyl peroxide 0.2 parts, n-octyl mercaptan 0.15 parts, deionized water 200 parts, calcium triphosphate 0.5 parts, calcium carbonate 0.3 parts, sodium lauryl sulfate 0.003.
Parts were added and mixed by stirring, and suspension polymerization was carried out at a reaction temperature of 80 ° C. for 140 minutes, followed by aging at 100 ° C. for 60 minutes to substantially complete the polymerization reaction, then cooling to 50 ° C. and addition of a mineral acid for washing and dehydration treatment. Then, a bead-like polymer was obtained. This copolymer had a weight average molecular weight of 130,000, a polymerization conversion rate of 99.6%, and a methyl acrylate (MA) copolymerization rate of 9.8%. All weight average molecular weights in the examples were adjusted by changing the amount of n-octyl mercaptan used.

Production of Copolymer (B) Two pieces of Teflon (registered trademark) processed metal plate cells using a soft vinyl chloride tube as a seal packing, 75 parts of methyl methacrylate, 15 parts of styrene, 10 parts of maleic anhydride, lauroylper. A monomer mixture of 0.05 part of oxide and 0.08 part of n-octyl mercaptan was charged and polymerized in a water tank at a reaction temperature of 50 ° C. for 25 hours, then at a reaction temperature of 70 ° C. for 5 hours, and then in an air bath. The polymerization reaction was substantially completed by aging at a reaction temperature of 120 ° C. for 5 hours, the obtained 20 mm plate was cooled, deframed from the metal plate cell, and crushed with a crusher to obtain a powdery polymer. The weight average molecular weight was 130,000 and the polymerization conversion rate was 99.1%. 60 parts of the copolymer (A) and 40 parts of the copolymer (B) are mixed by a Henschel mixer and supplied to a twin-screw extruder with a vent to granulate at a temperature of 240 to 250 ° C and a vent vacuum pressure of 700 to 750 mmHg. This pellet was injection-molded with M-70 manufactured by Meiki Seisakusho, and the molding temperature was 2
A flat plate molded product of 200 * 200 * 3 mm was obtained at 50 ° C.
The physical properties of this product are solvent resistance index (K) 700, MFR
2.1 g / 10 minutes, weather resistance index (W) 0.5, HDT1
The tensile strength was 03 ° C. and the tensile strength was 730 kg / cm ² .

[0017]

Example 2 A molded article was obtained in the same manner as in Example 1 except that the molecular weight of the copolymer (A) was 150,000 and the MA copolymerization rate was 12.9%. The physical properties of this product are solvent resistance index (K) 100
0, MFR 1.7 g / 10 min, weather resistance index (W) 0.
6, the HDT was 99 ° C. and the tensile strength was 720 kg / cm ² .

[0018]

Example 3 A molded article was obtained in the same manner as in Example 1 except that the molecular weight of the copolymer (A) was 100,000 and the MA copolymerization rate was 7.9%. The physical properties of this product are solvent resistance index (K) 350,
MFR 2.6g / 10 minutes, weather resistance index (W) 0.5, H
The DT was 105 ° C. and the tensile strength was 710 kg / cm ² .

[0019]

Example 4 A molded product was obtained in the same manner as in Example 1 except that the molecular weight of the copolymer (B) was changed to 110,000. The physical properties of this product are as follows: solvent resistance index (K) 400, MFR 2.4 g / 10
Minutes, weather resistance index (W) of 0.5, HDT of 103 ° C., and tensile strength of 700 kg / cm ² .

[0020]

Example 5 A molded article was obtained in the same manner as in Example 1 except that the copolymer (B) had a molecular weight of 150,000. The physical properties of this product are as follows: solvent resistance index (K) 1200, MFR 1.6 g / 10
Minutes, the weather resistance index (W) was 0.6, the HDT was 103 ° C., and the tensile strength was 730 kg / cm ² .

[0021]

Comparative Example 1 90 parts of copolymer (A) and 1 part of copolymer (B)
A molded product was obtained in the same manner as in Example 1 except that 0 parts were mixed. The physical properties of this product are solvent resistance index (K) 30, MFR
3.2 g / 10 minutes, weather resistance index (W) 0.4, HDT9
The tensile strength was 0 ° C. and the tensile strength was 730 kg / cm ² .

[0022]

Comparative Example 2 10 parts of copolymer (A) and 9 parts of copolymer (B)
A molded product was obtained in the same manner as in Example 1 except that 0 parts were mixed. The physical properties of this product are solvent resistance index (K) 1200, M
FR 1.5g / 10 minutes, weather resistance index (W) 3.2, HD
It had T108 ° C. and a tensile strength of 560 kg / cm ² .

[0023]

Comparative Example 3 A molded article was obtained in the same manner as in Example 1 except that the molecular weight of the copolymer (A) was 90,000 and the MA copolymerization rate was 2.8%. The physical properties of this product are solvent resistance index (K) 100 seconds,
MFR 1.9 g / 10 minutes, weather resistance index (W) 0.6, H
The DT was 107 ° C. and the tensile strength was 670 kg / cm ² .

[0024]

Comparative Example 4 A molded product was obtained in the same manner as in Example 1 except that the molecular weight of the copolymer (B) was changed to 80,000. The physical properties of this product are as follows: solvent resistance index (K) 70, MFR 2.8 g / 10 min, weather resistance index (W) 0.5, HDT 103 ° C., tensile strength 60
It was 0 kg / cm ² .

[0025]

Comparative Example 5 The monomer composition of the copolymer (B) was 65% methyl methacrylate, 21% styrene, 14 maleic anhydride.
A molded product was obtained in the same manner as in Example 1 except that the percentage was changed. The physical properties of this product are solvent resistance index (K) 900, MFR2.
7g / 10 minutes, weather resistance index (W) 3.5, HDT105
℃, it had a tensile strength of 550kg / cm ^2.

[0026]

Comparative Example 6 A similar molded article was obtained using Asahi Kasei Delpet 80NB (weight average molecular weight 180,000). The physical properties of this product are as follows: solvent resistance index (K) 450, MFR 0.5g / 1
The weather resistance index (W) was 0.4, the HDT was 95 ° C., and the tensile strength was 720.

[0027]

Comparative Example 7 A similar molded article was obtained using Asahi Kasei Delpet 80N (weight average molecular weight: 100,000). The physical properties of this product are as follows: solvent resistance index (K) 10, MFR 2.0 g / 10
Min, weather resistance index (W) 0.4, HDT 100 ° C., and tensile strength 730 kg / cm ² .

[0028]

[Table 1]

The monomer compositions and weight average molecular weights of the copolymers (A) used in Examples 1 to 5 and Comparative Examples 1 to 5 are collectively shown.

[0030]

[Table 2]

The monomer compositions and weight average molecular weights of the copolymers (B) used in Examples 1 to 5 and Comparative Examples 1 to 5 are collectively shown.

[0032]

[Table 3]

The resin compounding compositions and physical properties of Examples 1 to 5 and Comparative Examples 1 to 7 are collectively described.

[0034]

The product of the present invention is excellent in solvent resistance and fluidity, and does not impair the weather resistance and transparency which are peculiar to acrylic resin. A solvent resistant resin composition having excellent solvent crack resistance, high fluidity and excellent moldability and a lamp lamp for a vehicle can be provided.

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Claims (3)

[Claims] 1. A copolymer (A) 40-8 shown below.
A resin composition obtained by melt-mixing 0 part by weight and 60 to 20 parts by weight of the copolymer (B) according to JIS standard K7210,
A resin composition having a melt mass flow rate of 1.6 to 3.0 under a condition N and a solvent resistance index (K) of more than 300. However, solvent resistance index (K) = breaking time (second) when ethanol is applied at a load bending stress of 40 megapascals Copolymer (A) Methyl methacrylate unit 85-95 wt% Methyl acrylate unit 5-15 wt% Weight Average molecular weight 80 to 160,000 Copolymer (B) Methyl methacrylate unit 70 to 80 wt% Styrene unit 12 to 18 wt% Maleic anhydride unit 8 to 12 wt% Weight average molecular weight 12 to 160,000 2. The resin composition according to claim 1, which has a weather resistance index (W) of less than 2.0. However, the weather resistance index (W) = the difference between the yellowing degree after irradiation for 1000 hours by the Sunshear weather meter and the yellowing degree of the unirradiated product. 3. A vehicle lamp lens obtained by injection molding the solvent resistant resin composition according to claim 1.