JPH0912822A - Methacrylic resin composition - Google Patents

Abstract

PURPOSE: To produce a methacrylic resin composition which shows improved thermal discoloration resistance even when molded by e.g. injection at high temperatures and has good colorless and transparent appearance by adding a specified phosphite compound to a specified methacrylic polymer. CONSTITUTION: A phosphite compound (0.01-2.0 pts.wt.) represented by the formula (R1 and R2 , which may be the same or different from each other, are each an 8-18C alkyl, a cycloalkyl or a phenyl group which may contain 1-3 alkyl substituents with their total number of carbon atoms of 1-10) is added to 100 pts.wt. methacrylic polymer comprising 70-100wt.% methyl methacrylate, 0-30wt.% at least one alkyl methacrylate with a 1-8C alkyl and 0-30wt.% at least one alkyl methacrylate with a 2-8C alkyl. This composition has particularly good colorlessness and transparency and is therefore desirable for objects for which highly optical properties are necessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a methacrylic resin composition, and more particularly, it is suitable for optical applications such as lenses and light guides, which has improved heat coloring properties in high temperature injection molding, extrusion molding and the like. And a methacrylic resin composition.

[0002]

BACKGROUND OF THE INVENTION Since methacrylic resin is colorless and transparent, has a beautiful appearance and weather resistance, and is easy to mold, it is widely used for electrical parts such as louvers, tail lamps, lenses, tableware, vehicle parts, decorations, miscellaneous goods, and signs. It is used. However, a general-purpose methacrylic resin has a problem that it is slightly yellowish in injection molding and extrusion molding under the condition of being retained at a higher temperature for a long time. As a method of this improvement, the addition of a trace amount of blue dye has been tried, but it is insufficient, and particularly in optical applications such as special thick lenses and light guides, where better colorless transparency is required The current situation is that we have not fully met the demand.

[0003]

Therefore, the present invention has a better colorless and transparent property which has improved heat coloring property in injection molding at a high temperature and is particularly suitable for optical applications such as lenses and light guides. An object of the present invention is to provide a methacrylic resin composition having

[0004]

Means for Solving the Problems As a result of earnest research on a methacrylic resin composition having better colorless transparency, the present inventor has found that by adding a specific phosphite compound to a methacrylic polymer, The inventors have found that a methacrylic resin composition having improved yellowing properties such as injection molding and the like, having no yellowish color and having better colorless transparency can be obtained, and thus completed the present invention.

That is, the present invention uses methyl methacrylate 70
To 100% by weight, 0 to 30% by weight of at least one alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and at least one methacrylic acid alkyl ester having an alkyl group having 2 to 8 carbon atoms 0 ~ 30% by weight
Based on 100 parts by weight of the methacrylic polymer consisting of

[0006]

Embedded image

(In the formula, R ₁ and R ₂ have 8 to ₁ carbon atoms.
8 represents an alkyl group, a cycloalkyl group, or a phenyl group having a total carbon number of 1 to 10 and optionally having 1 to 3 alkyl substituents, and R ₁ and R ₂ are different groups. . ) 0.01 to 0.
This is achieved by a methacrylic resin composition containing 2 parts by weight.

Hereinafter, the present invention will be described in detail. In the methacrylic polymer used in the present invention, methyl methacrylate is a monomer that is a main component of the polymer, and is 70% by weight or more, preferably from the viewpoint of optical properties such as transparency and mechanical properties. It is necessary to be 80 to 99% by weight.

The other component, alkyl acrylate, is used for the purpose of adjusting fluidity and thermal properties,
The content is 0 to 30% by weight with respect to the total amount of the polymer,
It is more preferably 1 to 20% by weight. The acrylate alkyl ester is an acrylate alkyl ester having an alkyl group having 1 to 8 carbon atoms, and examples thereof include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Used in two or more kinds.

The methacrylic acid alkyl ester, which is another component, is used for the purpose of improving hygroscopicity, and the content thereof is 0 to 30% by weight, more preferably 5 to 5% by weight based on the total amount of the polymer. It is 20% by weight. The methacrylic acid alkyl ester is a methacrylic acid alkyl ester having an alkyl group having 2 to 8 carbon atoms, and examples thereof include butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, phenyl methacrylate and the like. Used in seeds and above.

As the method for producing the methacrylic polymer, known polymerization methods such as bulk polymerization, continuous bulk polymerization, continuous solution polymerization and suspension polymerization can be used.

In these polymerizations, known polymerization initiators, chain transfer agents, etc. are used. The phosphite compound used in the present invention has the following general formula (1)

[0013]

Embedded image

(In the formula, R ₁ and R ₂ have 8 to ₁ carbon atoms.
8 represents an alkyl group, a cycloalkyl group, or a phenyl group having a total carbon number of 1 to 10 and optionally having 1 to 3 alkyl substituents, and R ₁ and R ₂ are different groups. . ), For example, isodecyltridecylpentaerythritol diphosphite, nonyltridecylpentaerythritol diphosphite, nonylphenylisodecylpentaerythritol diphosphite, (2,4
-Di-t-butylphenyl) tridecyl pentaerythritol diphosphite, (2,6-di-t-butyl-4)
-Methylphenyl) nonylphenylpentaerythritol diphosphite and the like.

These phosphite compounds may be used alone or in combination of two or more. The content thereof is 0.01 to 0.2 part by weight, preferably 0.02 to 0.06 part by weight, relative to 100 parts by weight of the methacrylic polymer. If the amount added is less than 0.01 parts by weight, the effect of preventing heat coloring at high temperatures is insufficient, and good colorless transparency cannot be obtained. This is not preferable, because the properties are deteriorated, defects such as silver streak are likely to occur at the time of injection molding, and the hue is deteriorated due to burning.

Examples of the method for adding the phosphite compound include a method of adding the phosphite compound by dissolving it in a monomer at the time of polymerization, a method of adding and mixing with an extruder in pelletizing or sheeting, and the like, and is not particularly limited. There is no such thing.

To the methacrylic resin composition of the present invention, ultraviolet absorbers, lubricants, dyes and pigments, etc. usually used for methacrylic resins can be added, if necessary, within the range not impairing the object of the present invention.

[0018]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
In the examples, "%" and "parts" are all "wt%" and "parts by weight", and the abbreviations of the monomers and phosphites used may be those in the following ().

Methyl methacrylate (MMA) Cyclohexyl methacrylate (CHMA) Methyl acrylate (MA) Ethyl acrylate (EA) Nonylphenyl tridecyl pentaerythritol diphosphite (NTDP) Nonyl phenyl isodecyl penta Erythritol diphosphite (NIDP) * 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HOPO) * Triethylphosphite (TEP)

The physical properties of the molded articles in the examples were measured according to the following methods. (1) Spectral light transmittance, b value: ASTM-D1003
(Measurement in 200 mm length direction) (2) MFR: ASTM-D1238 (condition: 230
(° C, 3.8 kg)

Example 1 To 100 parts of methacrylic polymer beads consisting of 98% methyl methacrylate and 2% methyl acrylate and having an MFR of 2 g / 10 min, 0.05 part of nonylphenyl tridecyl pentaerythritol diphosphite was added. After the addition and mixing, pellets were obtained by melt-kneading with an extruder. Using this pellet, injection molding was performed under the conditions of a cylinder temperature of 250 ° C. and a molding cycle of 600 seconds, and 5 mm of 50 mm × 200 mm × 5 mm was used.
A mirror flat plate having an end face having a thickness of mm also having a mirror surface was obtained. The 200 mm long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product are as shown in Table 1, and were good results.

Examples 2 to 3 By changing the copolymerization composition of methacrylic polymer and MFR, and changing the kind and addition amount of phosphite, polymerized by addition to polymer beads in the same manner as in Example 1, and melted by an extruder. The mixture was kneaded to obtain pellets. These pellets were injection-molded under the conditions of a cylinder temperature of 250 ° C. and a molding cycle of 600 seconds to obtain a mirror flat plate having a 50 mm × 200 mm × 5 mm 5 mm thick end face having a mirror surface. The 200 mm long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product are as shown in Table 1, and were good results.

Comparative Example 1 Methacrylic polymer beads composed of 98% methyl methacrylate and 2% methyl acrylate and having an MFR of 2 g / 10 min were melt-kneaded with an extruder to obtain pellets. Cylinder temperature of 250 ° C. using this pellet, molding cycle 6
Injection molding under the condition of 00 seconds, 50mm × 200mm × 5
A 5 mm thick end face having a mirror face was also obtained.
Spectral light transmittance of 200 mm length of the obtained molded product, b
Table 1 shows the values and the appearance evaluation results of the molded products. The obtained molded product was inferior in colorless transparency to that of the example.

Comparative Example 2 To 100 parts of methacrylic polymer beads consisting of 92% methyl methacrylate and 8% ethyl acrylate and having an MFR of 15 g / 10 min, 0.4 part of nonylphenyl tridecyl pentaerythritol diphosphite was added. After the addition and mixing, pellets were obtained by melt-kneading with an extruder. Using this pellet, injection molding was performed under the conditions of a cylinder temperature of 250 ° C. and a molding cycle of 600 seconds, and 5 mm of 50 mm × 200 mm × 5 mm.
A mirror flat plate having an end face having a thickness of mm also having a mirror surface was obtained. Table 1 shows the 200-mm-long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product. The obtained molded product was inferior in colorless transparency to that of the example.

Comparative Example 3 9,10-dihydro-9-oxa-1 was added to 100 parts of methacrylic polymer beads consisting of 98% methyl methacrylate and 2% methyl acrylate and having an MFR of 2 g / 10 min.
0-phosphaphenanthrene-10-oxide 0.0
After adding and mixing 5 parts, the mixture was melt-kneaded with an extruder to obtain pellets. Using this pellet, injection molding was performed under the conditions of a cylinder temperature of 250 ° C. and a molding cycle of 600 seconds, and 50 mm × 2
A 5 mm thick end face of 00 mm × 5 mm was also obtained as a mirror flat plate. Table 1 shows the 200-mm-long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product. The obtained molded product was inferior in colorless transparency to that of the example.

Comparative Example 4 100 parts of methacrylic polymer beads composed of 85% methyl methacrylate and 15% methyl acrylate and having an MFR of 8.5 g / 10 min were mixed with 0.03% of triethylphosphite.
After adding and mixing 5 parts, the mixture was melt-kneaded with an extruder to obtain pellets. Using this pellet, injection molding was performed under the conditions of a cylinder temperature of 250 ° C. and a molding cycle of 600 seconds, and 50 mm × 2
A 5 mm thick end face of 00 mm × 5 mm was also obtained as a mirror flat plate. Table 1 shows the 200-mm-long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product. The obtained molded product was inferior in colorless transparency to that of the example.

[0027]

[Table 1]

Example 4 When polymerizing methacrylic polymer beads consisting of 95% methyl methacrylate and 5% methyl acrylate and having an MFR of 5 g / 10 min, 100 parts of the monomer was mixed with nonylphenylisodecylpenta. Erythritol diphosphite (0.04 parts) was added, dissolved and polymerized. There was no problem with the polymerization stability, and the polymer bead yield was 99.5%. The beads are melted and kneaded by an extruder to form pellets, and the pellets are used at a cylinder temperature of 250 ° C. and a molding cycle 60.
Injection molding under the condition of 0 seconds, 50mm × 200mm × 5m
A mirror flat plate having a 5 mm thick end surface of m as a mirror surface was also obtained. Spectral light transmittance of 200 mm length of the obtained molded product, b
The values and the evaluation results of the appearance of the molded product are as shown in Table 2, and were good results.

Example 5 Monomer 1 was used in the polymerization of methacrylic polymer beads consisting of 80% methyl methacrylate units and 20% cyclohexyl methacrylate units and having an MFR of 3 g / 10 min.
0.1 part of nonylphenylisodecylpentaerythritol diphosphite was added to and dissolved in 100 parts of the polymerization. Polymerization stability was no problem, and the polymer bead yield was 99.
It was 6%. The beads are melt-kneaded with an extruder to form pellets, and the pellets are used to obtain a cylinder temperature of 250.
Injection molding under conditions of ℃, molding cycle 600 seconds, 50m
A mirror flat plate having a 5 mm thick end surface of m × 200 mm × 5 mm as a mirror surface was also obtained. The 200 mm long spectral light transmittance of the obtained molded product, the b value, and the appearance evaluation result of the molded product are as shown in Table 2, and were good results.

Comparative Example 5 Methacrylic polymer beads composed of 95% methyl methacrylate and 5% methyl acrylate and having an MFR of 5 g / 10 min were melt-kneaded with an extruder to obtain pellets. Cylinder temperature of 250 ° C. using this pellet, molding cycle 6
Injection molding under the condition of 00 seconds, 50mm × 200mm × 5
A 5 mm thick end face having a mirror face was also obtained.
Spectral light transmittance of 200 mm length of the obtained molded product, b
Table 2 shows the values and the appearance evaluation results of the molded products. The obtained molded product was inferior in colorless transparency to that of the example.

[0031]

[Table 2]

Example 6 100 parts of methacrylic polymer beads consisting of 95% methyl methacrylate and 5% methyl acrylate and having an MFR of 1.2 g / 10 minutes were mixed with 0.05 parts of nonylphenyl tridecyl pentaerythritol diphosphite. Parts are added and mixed, and the cylinder temperature is 260 ° C. with a 50φ sheet extruder,
400m width by melt-kneading under the condition of extrusion rate 30kg / Hr
An extruded plate having a thickness of m × 5 mm was obtained. The measurement surface was cut from this extruded plate and mirror-polished to obtain a 50 mm × 200 mm × 5 mm mirror flat plate. The spectral light transmittance of the obtained flat plate having a length of 200 mm, the b value, and the appearance evaluation result of the flat plate are as shown in Table 3, and were good results.

Comparative Example 6 Polymer beads similar to those in Example 6 were melt-kneaded in a sheet extruder of 50φ at a cylinder temperature of 260 ° C. and an extrusion rate of 30 kg / Hr to obtain an extruded plate having a width of 400 mm × 5 mm. It was The measurement surface is cut from this extruded plate, mirror-polished and 5
A 0 mm × 200 mm × 5 mm mirror flat plate was obtained. Table 3 shows the spectral light transmittance of the obtained flat plate having a length of 200 mm, the b value, and the appearance evaluation result of the flat plate.

[0034]

[Table 3]

[0035]

As described above, the metallic resin composition of the present invention has a markedly improved heat coloring property in injection molding at high temperature, extrusion molding, etc., has no yellowish tint, and has a better colorless transparency. It is suitable for products that require higher optical properties such as lenses and light guides.

Claims (2)

[Claims] 1. 70 to 100% by weight of methyl methacrylate, 0 to 30% by weight of at least one alkyl acrylate ester whose alkyl group has 1 to 8 carbon atoms, and 2 to 8 carbon atoms of the alkyl group. Based on 100 parts by weight of a methacrylic polymer composed of 0 to 30% by weight of at least one alkyl methacrylate, the following general formula (1): (In the formula, R ₁ and R ₂ are an alkyl group having 8 to 18 carbon atoms, a cycloalkyl group, or 1 having a total carbon number of 1 to 10
~ Represents a phenyl group which may have 3 alkyl substituents, and R ₁ and R ₂ are different groups. ) 0.01-0.2 weight part of the phosphite compound shown by these are contained, The methacrylic resin composition characterized by the above-mentioned. 2. A methacrylic polymer comprising 80 to 100% by weight of methyl methacrylate and at least one alkyl acrylate ester having 0 to 2 carbon atoms in the alkyl group.
The methacrylic resin composition according to claim 1, which is a methacrylic polymer comprising 20% by weight.