JPH0381307A - Transparent heat-resistant styrenic copolymer - Google Patents

Abstract

PURPOSE:To prepare a transparent heat-resistant styrenic copolymer excellent in the processability, heat distortion resistance, mechanical strengths, transparency, etc., and suitable for a foamed sheet, etc., by introducing specific hydrocarbon units into a styrene/alpha-methylstyrene copolymer. CONSTITUTION:A styrenic copolymer which comprises 70-95mol% styrene units, 30-5mol% alpha-methylstyrene units, 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, phenyl, etc.), wherein the molar ratio of the units of formula I/(styrene units + alpha-methylstyrene units) is 0.06-0.000006. It has a reduced viscosity (25 deg.C, 0.3g/dl chloroform soln.) of 0.15-2dl/g, and is produced by copolymerizing styrene with alpha-methylstyrene 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 copolymer mainly composed of colorless and transparent styrene units, which has excellent mechanical strength when made into foam sheets and foam molded products.

(Prior Art) Polystyrene and a copolymer of acrylonitrile and styrene have been known as resins that have good transparency and processability and are available at low cost. However, these resins have problems in terms of heat resistance or mechanical strength, which inevitably limits their range of industrial use.

A known method for improving the heat resistance of polystyrene is to introduce α-methylstyrene into the molecular chain.

The mechanical strength of these copolymers is still not at a satisfactory level, especially when they are made into foam sheets and foam molded products, and their industrial application is inevitably limited.

(Means for Solving the Problems) In order to overcome such drawbacks of styrene and α-methylstyrene copolymers, the present inventors have conducted intensive studies and found that a specific hydrocarbon unit in the molecule By introducing the above, we have discovered a transparent styrene resin that has good processability and excellent properties for use in foamed sheets and thermoformed products using foamed sheets, and have completed the present invention.

That is, the present invention provides a styrene unit, an α-methylstyrene unit, and a general formula <I>: (wherein l, m, n are 1
is an integer of ~20, R1, L, L, R4 are hydrogen,
A methyl group, a cyclohexyl group, or a phenyl group, at least one of which is an alkyl group having 2 to 5 carbon atoms. ) It has been found that a copolymer having a molecular structure in which the structural units represented by the following formulas are randomly arranged in a predetermined ratio and having a reduced viscosity within a specific range satisfies the object of the present invention.

That is, the present invention includes: (A) 70 to 95 mol% of styrene units, (B) 5 to 30 mol% of α-methylstyrene units, and (C) the following general formula (
I): (wherein l, m%n are integers of 1 to 20, R1, R
O, Rs, and Ra are hydrogen, methyl group, cyclohexyl group, or phenyl group, and at least one of them is
One is an alkyl group having 2 to 5 carbon atoms. ) is a styrenic polymer consisting of structural units represented by (C) general formula (1), (A) styrene units, and (B) α-methylstyrene units in a molar ratio of (
F)/((＾)+(B))-0,006~0゜0000
06, and the temperature of a chloroform solution with a concentration of 0.3 g/a is 25
The reduced viscosity at °C is 0.15 to 2. The present invention relates to a transparent heat-resistant styrenic copolymer having a weight ratio of 0a/g.

The novel copolymer of the present invention has the above (^), (II),
(C) has a molecular structure in which each unit is randomly arranged, and among these, the (^) unit, that is, the styrene unit, improves the melt flowability of the copolymer and facilitates molding processing. In addition to improving properties, it is particularly important for controlling foamed micelles when forming acid foam sheets.

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%, problems arise with poor melt flow and properties. Moreover, if it exceeds 95 mol%, heat resistance may deteriorate, which is not preferable.

Further, it is important that the amount of the (B) unit, that is, the α-methylstyrene unit, is in the range of 5 to 30 mol%.

If the amount of α-methylstyrene units is less than 5 mol%, the heat resistance will not be improved sufficiently, and if it exceeds 30 mol%, the thermal stability during thermoforming will be insufficient. , giving rise to problems.

Function (C) of the present invention, that is, the following general formula (I): (wherein Lm%n is an integer of 1 to 20, Rr, 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 a carbon number.

) The constituent unit (C) represented by the II precept unit (C) and (
The molar ratio between A) styrene units and (B) α-methylstyrene units is (C)/((^)+(B)] -0,0
It is important that the range is from 06 to 0.000006.

If it is less than 0.006, the effect of improving mechanical strength is not sufficient, and if it exceeds 0.000006, the glass transition temperature will drop significantly and the cost will increase, which is not preferable.

The structural unit (C) represented by the general formula (1) is carried out as follows.

That is, after dissolving the polymer of the present invention in 10 times the amount of methyl ethyl ketone, the polymer is precipitated while being slowly added to the same amount of methanol. The polymer is dried for 30 minutes at 200° C. under a vacuum of 5 mHH.

Using this polymer, JNR-GX2 manufactured by JASCO ■
Mouth 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: lO■, measurement temperature: -120°C. As a result of these measurements, a peak derived from the carbon of the methylene group of the long chain alkyl appeared at 29.4 ppm, and a peak derived from the carbon of the methylene group of the long chain alkyl appeared at 29.4 ppm, and the carbon adjacent to the quaternary carbon in the long chain The peak derived from 33.
Appears at 7 ppm. The presence of the structural unit (C) represented by the general formula (1) can be confirmed by the appearance of these peaks.

The quantitative determination of the structural unit (C) represented by the general formula (1) is based on the amount of 3 derived from the methylene and methine groups of the structural unit (^) and CB).
29. relative to the total area of the peak appearing at 8 to 50 ppm.
It is also calculated from the peak area ratio of 4 ppm. The calibration curve required for calculation is created using polymers polymerized under the composition and polymerization conditions shown in Table 1 below.

1st front entrance ≠ H'AM: + CB-(Cut)i-), Hiron CHx
)*-C-0-0+ has 7 repeating units.

Monomers: Styrene and α-methylstyrene, blended in proportions corresponding to the examples.

The random copolymer of the present invention has a reduced viscosity of 0.1 at a temperature of 25°C in a chloroform solution with a concentration o and 3 g/d.
It is necessary to be in the range of 5 to 2.0 a/g. 0.
If it is less than 15a/g, the mechanical strength is low; 2.
If it exceeds 0a/g, moldability is insufficient and industrial use is restricted, which is not preferable.

The method for producing the resin of the present invention includes (^), (B)
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, and Rr
, Rt % Rs , R4 is hydrogen, a methyl group, a cyclohexyl group, or a phenyl group, and at least one
One is an alkyl group having 2 to 5 carbon atoms.

) of a low-temperature decomposition type organic peroxide represented by 0.0005 to 0.05 in terms of active oxygen amount per 100 parts by weight of monomer.
It is necessary to add and polymerize in parts by weight.

The low-temperature decomposition type organic peroxide contains at least 3, preferably 5 to 30, repeating units represented by the general formula (U), and has a halving rate of 10 hours in a temperature range of 40 to 100°C. It indicates the period.

The decomposition temperature of these organic peroxides is 10 and a half hours. sealed in a nitrogen-substituted glass tube,
It can be determined by repeating an experiment of immersing it in a constant temperature bath and thermally decomposing it while changing the temperature of the constant temperature bath, and according to the method described in JP-A-60-13805.

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

υ し tfls IJ In the present invention, it is advantageous to use a material with a 10-hour half-life of 40 to 100°C, and a material with a half-life of less than 40°C poses a risk of explosion during storage and handling. 10 more
If the temperature exceeds 0°C, the polymerization takes a long time, resulting in a significant decrease in productivity, and is therefore 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 amount of active oxygen referred to here refers to the active oxygen in peroxide bonds that exist in organic peroxides! It means the amount of (-0-).

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,
Coloring agents and the like can be added.

Such lubricants include stearic acid, behenic acid,
Zinc stearate, ethylene bis stearamide, etc. Also, as a plasticizer, mineral oil, polyethylene glycol, etc. are used. As an antioxidant, for example, 2.6-di-1-butyl-
4-methylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene glycol-bis-5-(3-t-butyl-4-hydroxy-5-methylphenyl) ) propionate, etc., as a flame retardant, for example, tri(2,4-
Examples include di-butylphenyl) phosphite, 4.4''-butylidene-bis(3-methyl-6-L-butylphenyl-di-tridecyl) phosphite, and the like.

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.

■ Reduced viscosity (ηsp/C): Dissolve 0.15 g of sample in 50 Jd 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 foam molded product: The copolymer of the present invention was extruded and foamed using Freon-12 as a foaming agent to form a sheet with a thickness of 1.2-1 and a density of 0.099 g/cc. A polystyrene foam of the shape was obtained. This sheet was subjected to repeated bending tests to evaluate its strength.

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

Example 1 (Assembling of glass cell) A glass cell was prepared by combining two sheets of tempered glass measuring 400 x 300 x 3 m and adjusting the gap using a vinyl chloride gasket so that three cast plates could be obtained.

(Polymerization) Styrene 87.5 parts by weight, α-methylstyrene 12.
5 parts by weight, 1.2 parts by weight of the initiator shown outside the frame in Table 1, α-
A polymerization reaction solution consisting of 0.50 parts by weight of methylstyrene dimer was injected from the injection port of the cell, and heated in a hot bath at 60°C for 50 minutes.
After polymerizing for an hour, the polymerization was carried out in an oven at 110°C for 2 hours. The polymerization reaction rate was 98%.

The results are shown in Table 2.

As a result of compositional analysis of the resulting copolymer using an infrared spectrophotometer and 1-co-CNMR, the composition of the obtained polymer was 89.5 mol% of ST units, 44 mol% of αMST units, and expressed by the following formula. Structural unit: 0.0082 mol%.

The reduced viscosity (ηsp/C) of this polymer was 0.98, and the repeated bending strength of the expanded eidomorphic crystals was 96%.

Comparative Example 1 Monomer &II shown in Table 2 was polymerized in the same manner as in Example 1.

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 can be used for foam sheet molding. As,
It can be used as food packaging containers 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 30 mol% of α-methylstyrene units, and (C) 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 (C) general formula (I), (A) styrene units, and (B) α-methylstyrene units in a molar ratio of (C)/[(A)+(B)]=0.006-0.000
006, and the temperature of a chloroform solution with 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.