JPH0381308A - Transparent heat-resistant styrenic copolymer - Google Patents

Abstract

PURPOSE:To improve the mechanical strengths by introducing specific hydrocarbon units into the molecular chain of a styrene/an unsatd. dicarboxylic acid/ methyl methacrylate copolymer excellent in the transparency, processability, heat resistance, etc. CONSTITUTION:A copolymer which comprises 70-95mol% styrene units (A), 5-25mol% unsatd. dicarboxylic acid units (B) (e.g. maleic acid units), 0-30mol% methyl methacrylate units (C), and the balance of the structural units of formula I (wherein l, m, and n are each 1-20; and R1, R2, R3, and R4 are each H, methyl, cyclohexyl, etc.) (D), wherein the molar ratio of D/(A+B+C) is 0.006-0.000006. It has a reduced viscosity (25 deg.C, 0.3g/dl chloroform soln.) of 0.15-2dl/g, and is produced by copolymerizing A, B, and C in the presence of a low-temp. decomposable org. peroxide of formula II (e.g. formula III).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel styrenic resin with excellent heat resistance.

More specifically, the present invention has good heat deformation resistance,
The present invention relates to a new colorless and transparent copolymer mainly composed of styrene units, which has excellent mechanical strength when made into two-wheel stretched sheets and foam molded products.

(Conventional Technique WI) Polycarbonate has conventionally been known as a transparent resin that has excellent heat resistance and high mechanical strength. However, this polycarbonate has drawbacks such as being too expensive as a general-purpose resin and having poor moldability.

On the other hand, polystyrene is known as a resin that has good transparency and processability and is available at low cost. However, polystyrene has problems in terms of heat resistance and mechanical strength, which inevitably limits its industrial use.

A copolymer of styrene and maleic anhydride (SMA) was developed to improve the heat resistance of polystyrene.
It is commercially available. This copolymer has a low molecular weight and mechanical strength comparable to that of polystyrene, but is susceptible to cranking due to distortion remaining in the molded product, which inevitably limits its industrial application.

(Means for Solving Till!) As a result of intensive studies to overcome the drawbacks of the copolymer of styrene and maleic anhydride, the present inventors discovered that a specific hydrocarbon in the molecular chain By introducing the unit, it has excellent heat deformation resistance and thermal stability, high mechanical strength, and good workability, making it excellent for use in two-wheel stretched sheet applications and thermoformed products using foam sheets. The inventors discovered a transparent, heat-resistant copolymer mainly composed of aromatic vinyl compound units having such characteristics, and completed the present invention.

That is, the present invention provides styrene units, unsaturated dicarboxylic acid units, methyl methacrylate units and general formula (I) (formula φ, j!, m, n are integers of 1 to 20, R+
, Rt, Rs, and Ra are hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one of them is an alkyl group having 2 to 5 carbon atoms. ) It has been found that a copolymer having a randomly arranged molecular species structure in a predetermined proportion and having a reduced viscosity within a specific range satisfies the purpose of the present invention. .

That is, the present invention includes: (I) 70 to 95 mol% of styrene units, (B) 5 to 25 mol% of unsaturated dicarboxylic acid units, (C) 0 to 30 mol% of methyl methacrylate units, and (D) the following general Formula (I
): (wherein Is ms n is an integer from 1 to 2o, and R1
%R1%Rs, Ra is hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one of them is an alkyl group having 2 to 5 carbon atoms. ) is a styrenic polymer consisting of structural units represented by (D) general formula (I), (A) styrene units, (B) unsaturated dicarboxylic acid units, (C) methyl The molar ratio with the methacrylate unit is (D)/((A) +
(B) + (C) ) -0,006~o,oo.

006, and the temperature of a chloroform solution with a concentration of 0.3 g/d1 is 2.
The present invention relates to a transparent heat-resistant styrenic copolymer having a reduced viscosity of 0.15 to 2.0 a/g at 5°C.

The novel copolymer of the present invention has the above-mentioned (A), (B), (
C) and (D) have a molecular structure in which each unit is randomly arranged, and among these, the (A) unit, that is, the styrene unit, improves the melt fluidity of the copolymer. In addition to improving molding processability, this is particularly important for controlling foamed micelles during foamed sheet molding.

It is important that the content of this styrene unit is in the range of 70 to 95 mol%. If the styrene content is less than 70 mol %, the melt flowability is poor and the moldability of the foamed sheet is poor. Also, 95 mol%
If it exceeds this, the heat resistance will deteriorate, which is not preferable.

Also, (B) TIi, min, i.e. the amount of unsaturated dicarboxylic acid units (it is important that it is in the range of 5 to 25 mol%. If the amount of unsaturated dicarboxylic acid units is less than 5 mol%) However, if the amount exceeds 25 mol %, the heat stability during thermoforming will be insufficient, causing problems.

Component (B) of the present invention, that is, a monomer that produces unsaturated dicarboxylic acid units, includes unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, and itaconic acid, or their anhydrides. However, maleic anhydride is preferred.

The amount of component (C) of the present invention, i.e., methyl methacrylate units, is preferably in the range of 0 to 30 mol%; if it exceeds 30 mol%, melt fluidity decreases and problems occur during molding. do not have.

(D) 6 minutes of the present invention, that is, the following general formula (I): (
During the ceremony, j! , m and n are integers from 1 to 20, and R+,
R1SRa and R4 are hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one of them is an alkyl group having 2 to 5 carbon atoms. ) is a styrenic polymer consisting of a structural unit (D) represented by the following general formula (I), and a structural unit (B) represented by the following general formula (I),
(A) styrene unit, (B) unsaturated dicarboxylic acid unit,
The molar ratio to (C) methyl methacrylate unit is (D)
/ ((A) +(B) +(C)) -0,006
˜0.000006.

If this molar ratio is less than 0.006, the effect of improving mechanical strength will not be sufficient. Moreover, if it exceeds 0.000006, the glass transition temperature will drop significantly, and the cost will increase, which is also undesirable.

The quantitative determination of the structural unit CD) represented by the general formula CI) is carried out as follows.

That is, the polymer of the present invention is dissolved in 10 times the amount of methyl ethyl ketone and then slowly added to the same amount of methanol to precipitate the polymer. This polymer was heated to 200″C
Dry for 30 minutes under vacuum at 13 mHg.

Using this polymer, JNR-GX2 manufactured by JASCO ■
Eye CNMR was measured using 70 under the following conditions.

Complete decoupling mode - 45 degree pulse, observation frequency 67.8 MH2°, waiting time - 2.5 seconds, number of scans - 100,000 times, sample concentration - 10 wt%, solvent - 1,1-tetrachloroethane (d2), Sample tube - 10 samples, measurement temperature - 120℃.

As a result of these measurements, a peak derived from the carbon of the methylene group of the long-wave alkyl appeared at 29.4 ppm, and a peak derived from the carbon adjacent to the quaternary carbon in the long chain appeared at 33.4 ppm.
Appears at 7 ppm. The presence of the structural unit (0) represented by the general formula (I) can be confirmed by the appearance of these peaks.

The quantitative determination of the structural unit CD) represented by the general formula (I) is based on the total area of the peak appearing at 38 to 50 ppm derived from the methylene and methine groups of the structural units (A), (B), and (C). It is also calculated from the peak area ratio of 4 ppm.

The calibration curve necessary for calculation is shown in Table 1 below.
, is created using polymers that are polymerized under polymerization conditions.

Table 1 It has 7 repeating units.

Monomers: Styrene, maleic anhydride, and methyl methacrylate, which were blended in proportions corresponding to the examples.

The random copolymer of the present invention has a reduced viscosity of 0.15 at a temperature of 25°C in a chloroform solution with a concentration of 0.3 g/d.
~2. It is necessary to be in the range of Oa/g. 0.1
If it does not satisfy 54/g, the mechanical strength is low and 2.0
If it exceeds a/g, moldability is insufficient and industrial use is restricted, which is not preferable.

The method for producing the resin of the present invention includes (A) to (C)
When carrying out bulk polymerization or suspension polymerization of monomers, the general formula (
■〉= (In the formula, j!, m, n are integers from 1 to 20, R1,
R1, Rs, and R4 are hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one of them is an alkyl group having 2 to 5 carbon atoms. ) A low-temperature decomposition type organic peroxide containing at least three repeating units represented by (A) styrene, (B) an unsaturated dicarboxylic acid, and (C) methyl methacrylate monomer.
0.0005 to O, O in terms of active oxygen amount per part by weight
It is necessary to add S in a proportion of parts by weight and polymerize.

The low-temperature decomposition type organic peroxide has at least 3, preferably 5 to 30, repeating units represented by the general formula (■,).
It has a half-life of 10 hours in the temperature range of 40 to 100°C.

The decomposition temperature of these organic peroxides, which exhibits a half-life of 10 hours, is such that they can be dissolved in a solvent relatively inert to radicals, such as toluene or benzene, at 0.0%. An experiment was conducted in which the solution was dissolved at a concentration of 1 mol/l, sealed in a nitrogen-substituted glass tube, immersed in a constant temperature bath, and thermally decomposed by changing the temperature of the constant temperature bath. It can be determined according to the method described in JP-A-13805.

Examples of such organic peroxides include those having the following repeating units.

In the present invention, this 10 hour half-life is 40 to 100
It is advantageous to use 'C', which is 40'
If it is less than C, there is a risk of explosion during storage and handling, and if it is more than 100° C., it will take a long time for polymerization, resulting in a significant decrease in productivity, so it is not practical.

In the present invention, the amount of this organic peroxide per 100 parts by weight of the styrene monomer is 0.000 in terms of activated carbon.
If it is less than 5 parts by weight, the time required for polymerization will be significantly longer and productivity will decrease, which is undesirable. If it exceeds 0.05 parts by weight, the production of high molecular weight polymers, which is one of the effects of the present invention, will be impaired. It becomes insufficient and undesirable.

The active oxygen amount here means the amount of active oxygen (-0-) in peroxide bonds present in the organic peroxide.

Specifically, the resin of the present invention is manufactured according to bulk polymerization or solution polymerization used in ordinary styrene polymerization methods, and the above-mentioned organic peroxide and, if desired, a solvent and other necessary additives are added to the raw material monomers. This can be carried out by inserting the mixture into a reactor and heating it while applying or reducing pressure as necessary.

Further, during this polymerization, a known organic peroxide may be used in combination, or may be added during the polymerization.

In addition, this polymerization method can be carried out stepwise by changing conditions such as polymerization temperature, and/or by changing the addition of monomers and/or organic peroxides, and by either batchwise or continuous method. can also be done.

From the polymerization solution thus obtained, the desired styrenic copolymer can be separated by removing unreacted monomers and solvents according to a conventional method.

In addition, in order to produce the resin of the present invention, continuous bulk polymerization method,
A suspension polymerization method or the like can be used.

In addition, additives commonly used for unreacted monomers and styrenic copolymers, such as oxidizing agents, lubricants, plasticizers, flame retardants,
It is recommended to add coloring agents, etc.

Such lubricants include stearic acid, behenic acid,
Zinc stearate, ethylene bis stearamide, etc. Also, as a plasticizer, neral oil, polyethylene glycol, etc. As an antioxidant, for example, 2.6-di-t-butyl-
4-Methylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxytuunyl)propionate, triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methyl Phenyl) propionate, etc., as a flame retardant, for example, tri(2,4-
Examples include di-t-butylphenyl) phosphite and 4,4°-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl) phosphite.

The novel styrenic copolymer of the present invention has excellent heat deformation resistance and processability, and has excellent mechanical strength, especially when made into foam sheets and foam molded products, and is colorless and transparent, and is a molding material for various products. In particular, it can be suitably used in foam molding materials.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited by the examples.

In addition, each physical property in an Example was calculated|required by the method shown below.

(2) Reduced viscosity (ηsp/C): 40.15 g of tlT is dissolved in 50 ad of chloroform. The number of seconds of flow is measured at 25° C. using a Cannon Fenske viscometer 50#, and calculated using the following formula.

t: Number of seconds for chloroform to flow; ■ Strength of foamed molded product: The copolymer of the present invention was extruded and foamed using Freon-12 as a foaming agent to a thickness of 1. 2am, density 0.099g/cc
A sheet-like polystyrene foam was obtained. This sheet was subjected to repeated bending tests to evaluate its strength.

Thirty samples were tested by bending along the circumference of a cylinder with a diameter of 50 amφ1, and the percentage of samples that did not crack was shown.

Example 1 (Assembling a glass cell) Two tempered glass plates of 400 x 300 x 3 m were combined, the gap was adjusted using a vinyl chloride gasket, and 311
A glass cell was prepared so as to obtain a cast plate of m.

(Polymerization) 90.0 parts by weight of styrene, 10 parts by weight of maleic anhydride,
A polymerization reaction solution consisting of parts by weight of initiators O and SO shown outside the frame of Table 1 was injected from the injection port of the cell, and placed in a hot bath at 60°C for 50 minutes.
After polymerization for 2 hours, the polymerization reaction rate was 98% after 2 hours of polymerization in an oven at 110'C.

The results are shown in Table 2.

Neutralization titration of the produced copolymer, infrared spectrophotometer and "C"
As a result of compositional analysis by NMR, the composition of the obtained polymer was 10 mol% of MAR units, 89.9 mol% of ST units, and 0.0072 mol% of structural units represented by the following formula.

The reduced viscosity (ηsp/C) of this polymer was 0.80, and the repeated bending strength of the foam molded product was 90%.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 using the monomer composition shown in Table 2.

The results are shown in Table 2.

(Effects of the Invention) The styrenic transparent heat-resistant resin of the present invention is novel, has excellent heat deformation resistance, thermal stability, and processability, has high mechanical strength, is colorless and transparent, and is molded into foam sheets. As a product, it can be used as food packaging containers that are heated in a microwave oven.

It can also be used as a material for automobile parts and lenses.

(1 other person)

Claims (1)

[Scope of Claims] (A) 70 to 95 mol% of styrene units, (B) 5 to 25 mol% of unsaturated dicarboxylic acid units, (C) 0 to 30 mol% of methyl methacrylate units, and (D) the following general Formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, l, m, n are integers from 1 to 20, R_1,
R_2, R_3, and R_4 are hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one of them is an alkyl group having 2 to 5 carbon atoms. ) is a styrenic polymer consisting of structural units represented by (D) general formula (I), (A) styrene units, (B) unsaturated dicarboxylic acid units, (C) methyl The molar ratio with the methacrylate unit is (D)/[(A)+
(B) + (C)] = 0.006 to 0.000006, and the temperature of the chloroform solution at a concentration of 0.3 g/dl is 2.
A transparent heat-resistant styrenic copolymer having a reduced viscosity of 0.15 to 2.0 dl/g at 5°C.