JPH06136058A - Thermoplastic resin having low water-absorption and optical part made therefrom - Google Patents

Abstract

PURPOSE:To provide a thermoplastic resin composed of three specific kinds of constituent units, having a specific weight-average molecular weight, exhibiting low hygroscopicity and small dimensional change and having excellent transparency, heat-resistance and mechanical strength. CONSTITUTION:The thermoplastic resin is composed of (A) 20-80mol% of the constituent unit of formula I (R<1> is 1-18C alkyl or 3-12C cycloalkyl), (B) 80-20mol% of the constituent unit of formula II (R<2> to R<4> are H or 1-8C alkyl) and (C) 1-40mol% of the constituent unit of formula III (R<5> is methyl; R<6> is 4-18C alkyl or 3-12C cycloalkyl) and has a weight-average molecular weight of 1X10<3> to 5X10<6> in terms of polystyrene. The above resin can be produced by the copolymerization of preferably N-cyclohexylmaleimide as the compound giving the component A, preferably isobutene as the component B and preferably a 12-18C methacrylic acid ester as the component C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a low water absorption rate consisting of an N-substituted maleimide type copolymer, a small dimensional change due to water absorption accompanying it, and excellent transparency, heat resistance and mechanical strength. The present invention relates to a resin and an optical component made of the resin.

[0002]

2. Description of the Related Art Conventionally, glass has been generally used as an optical material, but in recent years, a transparent polymer material has come to be used in view of productivity, weight reduction, cost and the like. As such a material, polymethylmethacrylate (hereinafter abbreviated as PMMA) is mainly used.

However, although PMMA is excellent in optical characteristics, it has a glass transition temperature (Tg) of about 100 ° C., so that it has insufficient heat resistance, and has a saturated water absorption rate of 2.1% and high water absorption. Due to the large dimensional change that accompanies it, use is restricted.

Various studies have been made on maleimide copolymers because they have high heat resistance. For example, a method of copolymerizing N-aromatic substituted maleimide with the above-mentioned methyl methacrylate is disclosed in JP-B-43-9753, JP-A-61-
JP-A-141715, JP-A-61-171708 and JP-A-62-109811 disclose a method of copolymerizing an N-aromatic substituted maleimide with a styrene resin.
JP-A-47-6891 and JP-A-61-76512
It is known from Japanese Patent Laid-Open Publication No. 61-276807. However, the resins obtained by these methods have better heat resistance as the N-aromatic substituted maleimide content increases, but have problems such as brittleness, poor processability, and coloration, and are problematic for use as an optical material. There is.

Further, the copolymer consisting of N-alkylmaleimide and olefin is a material excellent in transparency, heat resistance and mechanical properties, but further lower water absorption is desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin which has a low water absorption property, a small dimensional change due to water absorption, and an excellent transparency, heat resistance and mechanical strength. It is to provide an optical component.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of this problem, the present inventors have found that a specific N-substituted maleimide copolymer has low water absorption, transparency, heat resistance and mechanical properties. They have found that the resin has excellent strength, and completed the present invention.

That is, the present invention is based on 20
To 80 mol% is composed of at least one kind of constitutional unit represented by the following general formula (I), and
20 mol% consists of at least one kind of constitutional unit represented by the following general formula (II), and is 1 to 4 of the whole polymer.
0 mol% is composed of at least one kind of constitutional unit represented by the following general formula (III), and has a polystyrene-equivalent weight average molecular weight of 1 × 10 ³ or more and 5 × 10 ⁶ or less Regarding optical components.

[0009]

[Chemical 4]

(Here, R ¹ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms)

[0011]

[Chemical 5]

(Here, R ² , R ³ and R ⁴ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms)

[0013]

[Chemical 6]

(Wherein R ⁵ is hydrogen or a methyl group, R ⁶
Represents an alkyl group having 4 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) The above-mentioned resin is, for example, radical copolymerization of N-alkyl-substituted maleimides, olefins and (meth) acrylic acid esters. It can be obtained by the reaction. Examples of the compound giving the constituent represented by the general formula (I) include N
-Methylmaleimide, N-ethylmaleimide, Nn-
Propylmaleimide, N-i-propylmaleimide, N
-N-butylmaleimide, Ni-butylmaleimide,
Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-laurylmaleimide, N-stearyl Maleimide, N-cyclopropylmaleimide, N-
Examples thereof include N-alkyl-substituted maleimides such as cyclobutyl maleimide and N-cyclohexyl maleimide. From the viewpoint of heat resistance, maleimides having 1 to 6 carbon atoms, that is, N-
It is preferable to use methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, especially N-cyclohexylmaleimide. These can be used alone or in combination of two or more.

Examples of the compound giving the constituent represented by the general formula (II) are ethylene, isobutene, 2-methyl-1-butene, 2-methyl-1-pentene, 2-methyl-1-hexene and 1-methyl. -1-Heptene, 1-isooctene, 2-methyl-1-octene, 2-ethyl-1
-Pentene, 2-methyl-2-butene, 2-methyl-2
-Olefins such as pentene and 2-methyl-2-hexene are mentioned, and isobutene is preferably used from the viewpoint of heat resistance and mechanical properties. These can be used alone or in combination of two or more.

The compound which provides the constituent component represented by the general formula (III) is (meth) acrylic acid ester having 4 to 18 carbon atoms, such as n-butyl acrylate and n-butyl acrylate.
-Hexyl acrylate, cyclohexyl acrylate, lauryl acrylate, stearyl acrylate,
Examples thereof include n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate and stearyl methacrylate. Of these, it is preferable to use methacrylic acid esters having 6 to 18 carbon atoms, particularly 12 to 18 carbon atoms, from the viewpoint of low water absorption. When the carbon number is less than 4, the effect of lowering the water absorption is small, and when the carbon number exceeds 18, the heat resistance is lowered, which is not preferable. These can be used alone or in combination of two or more.

The content of the constituent component represented by the general formula (I) is 20 to 80 mol% of the whole polymer, and the content is 20 to 6
0 mol%, particularly 25 to 50 mol% is preferable. If the amount of this component (I) exceeds 80 mol%, the resulting polymer becomes brittle, which is not preferable, and if it is less than 20 mol%, the heat resistance of the produced polymer decreases, which is not preferable.

The content of the constituent component represented by the general formula (II) is 80 to 20 mol% of the whole polymer,
40 mol% is preferable. 80 mol% of this component (II)
If it exceeds 10 mol%, the heat resistance of the polymer is lowered, which is not preferable.

Further, the content of the constituent component represented by the general formula (III) is from 1 to 40 mol%, preferably from 1 to 25 mol%, particularly preferably from 1 to 10 mol%, based on the whole polymer.
When the content of this component (III) exceeds 40 mol%, the heat resistance of the polymer formed is lowered, which is not preferable.
When it is less than mol%, it does not contribute to the reduction of the water absorption of the polymer produced.

If necessary, other monomers may be copolymerized within the range not impairing the object of the present invention.
Other monomers include styrene, styrene derivatives such as α-methylstyrene, methylstyrene, chlorostyrene and bromostyrene, 1,3-butadiene, isoprene and halogen-substituted derivatives thereof, methyl methacrylate, ethyl methacrylate, methacrylic acid. Methacrylic acid esters such as phenyl, acrylic acid esters such as methyl acrylate, ethyl acrylate, phenyl acrylate, vinyl esters such as vinyl acetate, vinyl benzoate, etc. Methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, etc. Vinyl ethers, vinyl chloride, vinylidene chloride, maleic anhydride, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (2,6-diethylphenyl) maleimide, N-phenyl Maleimide, N-(2-chlorophenyl) one or more compounds selected from maleimide and acrylonitrile.

For the polymerization of these monomers, any of known polymerization methods such as bulk polymerization method, solution polymerization method, suspension polymerization method and emulsion polymerization method can be employed.

As the polymerization initiator, benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, t-butyl peroxide are used. Oxyacetate
, T-butyl peroxybenzoate, organic peroxides such as perbutyl neodecanoate or 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile) ), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 1,1'-azobis (cyclohexane-1)
-Carbonitrile) and other azo-based initiators.

Solvents usable in the solution polymerization method include benzene, toluene, xylene, ethylbenzene,
Cyclohexane, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, dimethylformamide,
Examples include isopropyl alcohol and butyl alcohol.

The polymerization temperature can be appropriately set according to the decomposition temperature of the initiator, but generally it is preferably carried out in the range of 40 to 150 ° C.

The amount of residual maleimide monomer contained in the polymer is 3% by weight or less, preferably 1% by weight or less, particularly preferably 0.1% by weight or less, and when the residual monomer exceeds 3% by weight. The obtained polymer tends to be colored, which is not preferable.

Here, the weight average molecular weight (Mw) of the produced resin can be determined by gel permeation chromatography (GPC). The resin of the present invention has a molecular weight of 1 × 10 ³ or more and 5 × 10 ⁶ or less, particularly 1 × 10 ⁵
It is preferably 1 × 10 ⁶ or less. Molecular weight is 5 × 1
If it exceeds 0 ⁶ , the moldability tends to be poor, and if it is less than 1 × 10 ^{3, the} resin obtained tends to become brittle.

The resin obtained in the present invention includes
If necessary, heat stabilizers such as hindered phenols and organic phosphates, benzotriazole-based UV absorbers, hindered amine-based UV stabilizers, various lubricants and dyes may be added. Further, another resin compatible with this can be mixed.

The resin of the present invention has low water absorption, and
Along with this, the dimensional change due to water absorption is small, and the transparency, heat resistance and mechanical strength are excellent, and it is useful as various optical parts.

Optical parts include compact disk lenses, laser printer lenses, video lenses, spherical lenses such as camera lenses, aspherical lenses, optical lenses such as eyeglass lenses, optical fibers, optical disks and optical card substrates, Examples include automotive lenses such as prisms, headlight lenses, fog light lenses, turn lenses, and brake lamp lenses, signal lenses, and lighting parts.

Examples of the method for molding the resin of the present invention include ordinary molding methods such as injection molding, extrusion molding, compression molding and spin coating.

The obtained molded body is hard-coated,
An antireflection coat or the like can be applied.

[0032]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples.

The molecular weight of the produced polymer was determined by polystyrene conversion using GPC (Tosoh Corp. HLC-802A).

The Tg of the produced polymer was measured using DSC200 manufactured by Seiko Denshi KK

The light transmittance was measured according to ASTM 1746.

The saturated water absorption and the dimensional change due to water absorption are
It was measured according to JIS K 7209 and JIS K 7114.

The obtained polymer was pelletized by Labo Plastomill (Toyo Seiki Co., Ltd.) and a test piece was molded by using a small injection molding machine (Panajection; manufactured by Matsushita Electric Industrial Co., Ltd.). Flexural strength was evaluated according to ASTM D790.

Example 1 632 g of N-cyclohexylmaleimide and 10 lauryl methacrylate were placed in a 10 l autoclave equipped with a stirrer, a nitrogen introducing tube, an isobutene introducing tube, a thermometer and a degassing tube.
After charging 0 g, perbutyl neodecanoate 3 g and dioxane 5 l and purging with nitrogen several times, liquefied isobutene 2.8 l was charged and reacted at 60 ° C. for 5 hours.

The reaction contents were poured into ethanol to precipitate a polymer. The obtained polymer was purified by reprecipitation with chloroform / ethanol and then dried under reduced pressure at 60 ° C. for 24 hours. The yield was 840 g.

From the results of ¹ H-NMR measurement and elemental analysis of the obtained polymer, the maleimide unit in the produced polymer was 46 mol%, the lauryl methacrylate unit was 4 mol%, and the isobutene unit was 50 mol%. The obtained polymer had a molecular weight (Mw) of 345,000. The characteristic evaluation results are shown in Table 1.

Example 2 The same apparatus as in Example 1 was charged with 632 g of N-cyclohexylmaleimide, 300 g of lauryl methacrylate, 3 g of perbutyl neodecaneate and 5 l of dioxane,
After purging with nitrogen several times, 2.8 l of liquefied isobutene was charged and the reaction was carried out at 60 ° C for 5 hours.

The reaction contents were poured into ethanol to precipitate a polymer. The obtained polymer was purified by reprecipitation with chloroform / ethanol and then dried under reduced pressure at 60 ° C. for 24 hours. The yield was 850 g.

From the results of ¹ H-NMR measurement and elemental analysis of the obtained polymer, the maleimide unit in the produced polymer was 44 mol%, the lauryl methacrylate unit was 6 mol%, and the isobutene unit was 50 mol%. The obtained polymer had a molecular weight (Mw) of 327,000. The characteristic evaluation results are shown in Table 1.

Example 3 A device similar to that of Example 1 was charged with 632 g of N-cyclohexylmaleimide, 163 g of hexyl methacrylate, 3 g of perbutyl neodecanoate and 5 l of dioxane,
After purging with nitrogen several times, 2.8 l of liquefied isobutene was charged and the reaction was carried out at 60 ° C for 5 hours.

The reaction contents were poured into ethanol to precipitate a polymer. The obtained polymer was purified by reprecipitation with chloroform / ethanol and then dried under reduced pressure at 60 ° C. for 24 hours. The yield was 830 g.

From the results of ¹ H-NMR measurement and elemental analysis of the obtained polymer, the maleimide unit in the produced polymer was 40 mol%, the hexyl methacrylate unit was 10 mol%, and the isobutene unit was 50 mol%. The obtained polymer had a molecular weight (Mw) of 230,000. The characteristic evaluation results are shown in Table 1.

Comparative Example 1 N-cyclohexylmaleimide (632 g), perbutyl neodecanoate (3 g) and dioxane (5 l) were charged in the same apparatus as in Example 1, purged with nitrogen several times, and liquefied isobutene (2.8 l) was charged at 60 ° C. The reaction was carried out for 5 hours.

The reaction contents were poured into ethanol to precipitate a polymer. The obtained polymer was purified by reprecipitation with chloroform / ethanol and then dried under reduced pressure at 60 ° C. for 24 hours. The yield was 760 g.

From the results of ¹ H-NMR measurement and elemental analysis of the obtained polymer, the maleimide unit and the isobutene unit in the produced polymer were 50 mol% and 50 mol%, respectively.
The obtained polymer had a molecular weight (Mw) of 266000. The characteristic evaluation results are shown in Table 1.

Comparative Example 2 Acrylic resin (Acrypet V manufactured by Mitsubishi Rayon Co., Ltd.)
The same measurement was performed using H). Table 1 shows the characteristic evaluation results.
Shown in.

[0051]

[Table 1]

[0052]

As is clear from the examples, the thermoplastic resin of the present invention is excellent in transparency, heat resistance and mechanical strength, and has significantly improved water absorption and dimensional stability due to water absorption. These are useful as optical materials for various optical parts and lighting parts.

Claims (2)

[Claims] 1. 20 to 80 mol% of the whole polymer is composed of at least one kind of structural unit represented by the following general formula (I), and 80 to 20 mol% of the whole polymer is represented by the following general formula (II). 1 to 40 mol% of the whole polymer consists of at least one kind of constitutional unit represented by the following general formula (III), and has a polystyrene-equivalent weight average molecular weight of 1 × 1.
Resin that is 0 ³ or more and 5 × 10 ⁶ or less. [Chemical 1] (Here, R ¹ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) (Here, R ² , R ³ and R ⁴ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms) (Here, R ⁵ is hydrogen or a methyl group, R ⁶ has 4 to 4 carbon atoms.
18 alkyl group or C3-12 cycloalkyl group is shown) 2. An optical component made of the resin according to claim 1.