JPS61204251A - Styrene resin composition having excellent optical property - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent moldability and heat-resistance and suitable for optical information recording medium, by compounding a specific aromatic vinyl monomer-maleic monomer copolymer with an aromatic vinyl monomer-(meth)acrylonitrile copolymer. CONSTITUTION:The objective composition is produced by compounding (A) a copolymer composed of (i) 90-40mol% aromatic vinyl monomer (e.g. styrene), (ii) 10-60% one or more maleic monomers selected from maleic anhydride, maleimide, N-alkylmaleimide and N-arylmaleimide (e.g. N-phenylmaleimide), and (iii) 0-20% vinyl monomer residue copolymerizable therewith [e.g. (meth) acrylic acid] and (B) a copolymer composed of (iv) 80-50% aromatic vinyl monomer residue, (v) 20-50% (meth)acrylonitrile residue and (vi) 0-30% vinyl monomer residue copolymerizable therewith. The weight ratio of A/B is preferably (40-100)/(60-0), and the average molecular weight (in terms of polystyrene) of the composition is (7-14)X10<4>.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a styrenic resin composition with excellent optical properties, and particularly a styrene resin composition suitable for manufacturing optical information recording media. Regarding the composition.

``Prior Art'' Conventionally, materials such as glass, polymethacrylonite, and polycarbonate have been used to manufacture optical information recording media such as optical video discs, digital audio discs (compact discs), and optical discs for computers. It was used.

These materials were chosen because of their high transparency (,?IIB
This is because it has excellent optical properties, such as showing no distortion.

[Problems to be Solved by the Invention] However, even these materials were still not satisfactory. That is, glass has problems such as being heavy, easily broken, and not easy to mold.

Furthermore, although polymethacrylonite has excellent optical properties such as transparency and birefringence, and moldability, it has low heat resistance and high hygroscopicity, which causes problems such as deformation of the disk and deterioration of the recording layer. Ta.

In order to improve the optical properties, moldability, etc. of polycarbonate, it is necessary to lower the molecular weight, which results in a decrease in mechanical properties.

On the other hand, styrene-based resins have good moldability, etc., but have large birefringence, and even those with good phase retardation have a phase angle of about 70° (VF 1986-83009
Publication No.).

Styrene-maleic anhydride copolymers or imidized products thereof are also known (Japanese Patent Application Laid-Open No. 57-55701),
MFR is 0.8g 710 minutes (220℃.

JIS K 7210 In the present invention, the average molecular weight in terms of polystyrene is about 1.7X105),
It could not be used because of poor moldability and residual strain.

The present inventor has conducted extensive research with the aim of developing a styrenic resin composition that has excellent optical properties and good heat resistance, and has thus arrived at the present invention.

"Means for Solving the Problems" The above object of the present invention is to contain the following component (A) in an amount of 10 to 100%.
Contains 90 to 0 weight% of component (B) below, and has an average molecular weight of 7 x 104 to 1.4 in terms of polystyrene.
This is achieved using a styrenic resin composition with excellent optical properties, which is X10S.

(A) 90 to 40 mol% vinyl aromatic monomer residue,
10 to 60 mol% of at least one maleic monomer residue selected from the group consisting of maleic anhydride, maleimide, N-alkylmaleimide, and N-arylmaleimide
, and vinyl monomer residues copolymerizable with these O~20
A copolymer consisting of mol%.

(B) 80 to 50 mol% of a vinyl aromatic monomer, 20 to 50 mol% of at least one monomer residue selected from the group consisting of acrylonitrile and methacrylonitrile,
and a copolymer comprising 0 to 30 mol% of vinyl monomer residues copolymerizable with these.

Of the two components constituting the composition of the present invention, component (A) is an essential component, and among the three monomer residues constituting the copolymer of component (A), vinyl aromatic monomer mer residues and maleic monomer residues are essential monomer residues.

Therefore, the vinyl aromatic monomers that provide the most major monomer residues include styrene, a-methylstyrene, p-
Furkylstyrenes such as methylstyrene, 0-methylstyrene and -1-methylstyrene, halogenated styrenes such as chlorostyrene and bromostyrene, vinylnaphthalene and the like are used.

The maleic monomer providing the other essential monomer residue is selected from the group consisting of maleic anhydride, maleimide 1, N-alkylmaleimides and N-arylmaleimides. Examples of the N-alkylmaleimides include linear ones having about 1 to 10 carbon atoms, such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, and N-cyclohexylmaleimide;
A maleimide substituted with a branched or cyclic alkyl group is used.

As the N-arylmaleimide, N-phenylmaleimide F, N-)lylmaleimide, N-s7tylmaleimide, etc. are used.

Monomers that give copolymerizable vinyl monomer residues, which can optionally be combined with the above two monomer residues, do not seriously impair the excellent optical properties of the composition of the invention. Any vinyl monomer can be selected within reasonable limits, but esters of acrylic acid or methacrylic acid, such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, Preferred are acrylic esters such as pencil acrylate, and methacrylic esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate or benzyl methacrylate.

A preferred composition of component (A) is 90 to 40 mol% of vinyl aromatic monomer residues made of styrene, 10% of maleic monomer residues made of maleic anhydride, N-arylmaleimides, or a mixture thereof. 60 mol %, and 0 to 20 mol % of copolymerizable vinyl monomer residues made of esters of acrylic acid or methacrylic acid.

The ratio of each monomer residue constituting component (A) was determined for the following reasons.

If the maleic monomer residue is less than 10 mol%, the optical properties will deteriorate and the heat resistance will also deteriorate, so it is not preferable. Both are unfavorable because the compatibility decreases.Also,
If the copolymerizable vinyl monomer residue exceeds 20 mol %, hygroscopicity increases, which is not preferable.

Component (B) contains 80 to 50 mol% of vinyl aromatic monomer residues, preferably 75 to 60 mol% of vinyl aromatic monomer residues, and 20 to 20% of at least one monomer residue selected from the group consisting of acrylonitrile and methacrylonitrile. ~50 mol%, preferably 25
It is a copolymer consisting of ~40 mol% and O~30 mol% of vinyl monomer residues copolymerizable with these.

The vinyl aromatic monomer residue and the monomer providing the vinyl monomer residue copolymerizable therewith are selected from the same range as the monomer used in component (A). Similarly, styrene is preferred as the former, and esters of acrylic acid or methacrylic acid are preferred as the latter. If the ratio of each monomer residue constituting component (B) is outside the above range, moldability, optical properties, etc. will deteriorate, which is not preferable.

The composition of the composition of the present invention, that is, the blending ratio of component (A) and component CB) is such that component (A) is 10 to 100% by weight, preferably 40 to 100% by weight, and component (B) is 90% by weight.
It is selected within the range of 0 to 0% by weight, preferably 60 to 0% by weight. In any case, if the content of component (A) is less than 10% by weight, the heat resistance will not improve, which is not preferable.

The composition of the present invention is expressed in polystyrene equivalent average molecular weight L
, 7xl O' to L4xl Qs, and preferably within the range of 1.9x105 to 1.2x1OS. If this value is less than 7x105, the mechanical strength will deteriorate. decreases, while i, 4xio
If it exceeds s, moldability deteriorates, residual strain occurs in the molded product, and as a result, optical properties deteriorate, which is not preferable.

In the present invention, "average molecular weight in terms of polystyrene" refers to the composition measured by GPC method (GPC method) under the measurement conditions listed in Table 1.
el-Permation Chromat
The peak position of the obtained chromatogram is expressed by the weight average molecular weight of the corresponding monodisperse polystyrene when measured by the ollraphy method. Note that under the following measurement conditions, the composition of the present invention gives a single peak.

@Table 1 The composition of the present invention can also be prepared by kneading component (A) and optionally component (B) using an extruder, Banbury mixer, or the like. In this), component (A) and component (B) are
The above-mentioned monomer mixture mixed at a predetermined ratio,
It can be obtained by copolymerization using bulk, bulk-suspension, suspension or emulsion polymerization methods. However, each monomer mixture providing both components (A) and (B) may be added simultaneously or sequentially to 2
The compositions of the invention can also be prepared by stepwise polymerization. However, the molecular weight of the copolymer can be adjusted by changing the amounts, timing of addition, etc. of the initiator and chain transfer agent during polymerization. Furthermore, when component (A) of the composition of the present invention contains a maleimide, N-alkylmaleimide or N-arylmaleimide residue, maleic anhydride is used instead of maleimide, N-alkylmaleimide or N-arylmaleimide. Component (A) obtained by copolymerization with ammonia, methylamine, aniline, or other desired amine may be modified to produce the component.

The composition of the present invention comprises higher fatty acid esters, amides,
A lubricant such as alkali metal salts, an ultraviolet stabilizer such as benzotriazole, and various other auxiliary agents may be used in combination.

"Effects of the Invention" The composition of the present invention has excellent optical properties such as low birefringence and high transparency. *It also has good heat resistance and is not hygroscopic.

Furthermore, since the moldability is good, residual strain does not occur even when molded by injection molding.

Therefore, by using the composition of the present invention, various types of optical information recording media can be manufactured at low cost and in large quantities, so that it has great industrial utility value.

"Example" The present invention will be explained in more detail with reference to Examples and Comparative Examples.

In each of the following examples and comparative examples, methods for measuring various physical properties,
The test piece or device used for the measurement is as follows.

Test piece: The resin composition was pelletized using a vented 1-inch extruder, and then using a 1-ounce injection molding machine at a resin temperature of 240°C and a mold temperature of 90°C, 1.2 x 5
A test piece of mm×50 m+s was prepared.

Birefringence: Measured using a Nippon Kogaku Co., Ltd. fissure light microscope equipped with a Senarmont type compensator at a position 10 mm from the dead end side of the test piece using a light beam with a wavelength of 5461. The magnitude of the read letter silan (phase delay) is expressed in wavelength units (
expressed in nm).

Average molecular weight in terms of polystyrene: The GPC device used was a model 150C manufactured by Waters. As the GPC column, two Sy1-Rex A-80M manufactured by Showa Denko K.K. were connected in series.

Heat resistance: JIS K-7206 Tensile strength: JIS K-7113 Impact strength: JIS K-7110 Example 1 A container equipped with a stirrer, a thermometer, a monomer continuous addition device, a reflux condenser, and a nitrogen gas inlet 544 g of styrene and 18 g of maleic anhydride (MA) were placed in an i12+ glass autoclave, and the mixture was replaced with nitrogen while stirring.
Raise the internal temperature of the autocup to 110℃.

Next, keep the autoclave internal temperature constant at 110°C,
MAloog at a constant speed for 150 minutes.
Bulk polymerization was carried out while continuously adding it to the polymerization system.

When the continuous addition was completed, the polymerization rate was 49% by weight, and the MA residue content of the produced copolymer was 32% by mole. To this system, 138 g of acrylonitrile was added over 15 minutes while the temperature of the system was lowered to 90°C, and at this temperature an additional 20
It was stirred for a minute.

To this system, 0.4 g of a polyvinyl alcohol suspending agent and 650 g of water were added to bring the system into a suspended state. to this,
0.8 g of azobisisobutyronitrile and 4 g of t-dodecylmercaptan were added, and polymerization was carried out at 75° C. for 120 minutes. Then, the temperature was raised to 95° C. over 30 minutes, and stripping was performed at this temperature for 60 minutes. The obtained bead-shaped polymer was washed with water and dried.

As a result of analyzing this bead, it was found that component (A) was 48% by weight, consisting of 33% by mole of MA residue and 67% by mole of styrene residue.
It was found that it was a mixture of 52% by weight of component (B), consisting of 48% by mole of acrylonitrile residues and 52% by moles of styrene residues. In addition, the average molecular weight in terms of polystyrene is i, o
It was oxios.

A test piece was prepared from this bead and various physical properties were evaluated. The results are shown in Table 2.

Comparative Example 1 In Example 1, except that t-dodecylmercaptan was not added at all in the polymerization step after transfer to the suspension system,
The same procedure as in Example 1 was carried out.

The composition of the obtained beads was the same as in Example 1, but
The average molecular weight in terms of polystyrene was 1.66 x 105. The physical properties are shown in Table 2.

Example 2 Polymerization was carried out in the same manner as in Example 1, followed by stripping, the temperature was raised to 150°C, and aniline 12
3 g was added and imidization reaction was carried out for 120 minutes. The obtained bead-shaped polymer was washed with water and dried.

The composition of this bead-shaped polymer is 30 mol% of N-phenylmaleimide residues, 3 mol% of MA residues, and 6 mol% of styrene residues.
Component (A) consisting of 7 mol% was 53% by weight, and component (B) consisting of 46 mol% of acrylonitrile residue and 54 mol% of styrene residue was 47% by weight.

The polystyrene equivalent molecular weight of the composition is 1.06×10
It was 5. Various physical properties are shown in Table 2 below.

Table 2 As is clear from Table 2, the composition of the present invention had birefringence of 38 nm or less (corresponding to an angle of 25°) in retardance a value, and other physical properties were also good.

Example 3 657g of styrene was added to the autoclave used in Example 1.
1.6 g of %t-dodecylmercaptan and 22 g of MA were charged, and the internal temperature of the autoclave was raised to 110° C. while stirring and purging with nitrogen.

Next, keep the autoclave internal temperature constant at 110°C,
Bulk polymerization was carried out while 121 g of MA was continuously added to the polymerization system at a constant rate over 160 minutes. The polymerization rate at the completion of continuous addition was 51% by weight.

The resulting syrupy product was dissolved in methyl ethyl ketone. This solution was dropped into n-hexane to reprecipitate the polymer, and the polymer was separated.

The composition of the separated polymer, namely component (A), is M
The Afi group was 33 mol%, the styrene residue was 67 mol%, and the average molecular weight in terms of polystyrene was 1.00×105.

Various physical properties are shown in Table 3.

Comparative Example 2 The same procedure as in Example 3 was carried out except that the amount of monododecyl mercaptan used was 3.6 g. When the continuous addition was completed, the polymerization rate was 48% by weight, and the MA residue content in the produced copolymer was 34% by mole. The average molecular weight in terms of polystyrene was 6.5×105. Various physical property values are shown in Table 3.

Comparative Example 3 All t-dodecyl mercaptan (not used)
The same procedure as in Example 3 was conducted except that the polymerization time was 150 minutes. Polymerization rate 51% by weight upon completion of continuous addition,
The MA residue content of the produced copolymer was 33 mol%, and the average molecular weight in terms of polystyrene was 1.56×105. Various physical property values are shown in Table 3.

Comparative Example 4 The amount of maleic anhydride initially charged was 2.6 g, the amount of maleic anhydride continuously charged was 39 g, and the polymerization time was 3.
The same procedure as in Example 3 was carried out except that the time was 50 minutes.

When the continuous addition was completed, the polymerization rate was 47% by weight, the maleic anhydride residue content of the resulting copolymer was 9 mol%, and the average molecular weight in terms of polystyrene was 1.22×10S. The physical properties of this product are shown in Table 3.

Table 3 As is clear from Table 3, the compositions of Comparative Examples whose polystyrene equivalent molecular weight is 7X105 or less have low mechanical strength and cannot be used as molding materials for optical discs, etc.; , has large birefringence and cannot be used as a material for optical discs.

Patent applicant Mitsubishi Monsanto Chemical Co., Ltd. Agent
Patent Attorney Hase - (1 idiot)

Claims (2)

[Claims] (1) 10 to 100% by weight of the following component (A) and the following (
A styrenic resin composition with excellent optical properties, containing 90 to 0% by weight of component B) and having an average molecular weight in terms of polystyrene of 7 x 10^4 to 1.4 x 10^5. (A) 90 to 40 mol% of vinyl aromatic monomer residues, at least one maleic monomer residue selected from the group consisting of maleic anhydride, maleimide, N-alkylmaleimides, and N-arylmaleimides; A copolymer consisting of 10 to 60 mol% and 0 to 20 mol% of vinyl monomer residues copolymerizable with these. (B) 80 to 50 mol% of a vinyl aromatic monomer residue, 20 to 50 mol% of at least one monomer residue selected from the group consisting of acrylonitrile and methacrylonitrile, and copolymerizable with these. A copolymer consisting of 0 to 30 mol% of vinyl monomer residues. (2) The composition according to claim 1, wherein the component (A) is 40 to 100% by weight, and the component (B) is 60 to 0% by weight.