JPH0381309A - Transparent heat-resistant styrenic copolymer - Google Patents

Abstract

PURPOSE:To improve the mechanical strengths by introducing specific hydrocarbon units into a styrene/alpha-methylstyrene/methacrylic acid/methyl methacrylate/ six-membered cyclic acid anhydride copolymer excellent in the transparency, processability, heat resistance, etc. CONSTITUTION:A copolymer which comprises 70-90mol% styrene units (A), 5-20mol% alpha-methylstyrene units (B), 1-15mol% methacrylic acid units (C), 1-25mol% methyl methacrylate units (D), 0.5-1.5mol% six-membered cyclic acid anhydride units of formula I (E), and the balance of the structural units of formula II (wherein l, m, and n are each 1-20; and R1, R2, R3, and R4 are each H, methyl, cyclohexyl, etc.) (F), wherein the molar ratio of F/(A+B+C+D+E) is 0.006-0.000006. It has a reduced viscosity (25 deg.C, 0.3g/dl chloroform soln.) of 0.15-2dl/g.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel heat-resistant styrenic copolymer.

More specifically, the present invention discloses a new material based on a colorless and transparent styrene unit, which has excellent heat deformation resistance, thermal stability, processability, and particularly mechanical strength when made into foam sheets and foam molded products. The present invention relates to a copolymer.

(Prior Art) Polycarbonate is conventionally known as a transparent resin with 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 methacrylic acid (SMAA) is an improved version of polystyrene with improved heat resistance.

A copolymer of styrene and maleic anhydride (SMA) has been developed and is commercially available. The mechanical strength of these copolymers is still equivalent to that of polystyrene, and cracks are likely to occur due to distortion remaining in the molded product, so that their industrial application is still limited.

In order to overcome the drawbacks of polystyrene and styrene-based copolymers, for example, styrene with methyl methacrylate introduced into the polymer main chain, terpolymer of methacrylic acid and methyl methacrylate, or styrene, α
- Quaternary copolymers of methylstyrene, methacrylic acid and methyl methacrylate have been developed.

However, when molded products are obtained by injection molding these terpolymer and quaternary copolymers, silver streaks occur on the surface of the molded product, which poses a problem.

This phenomenon occurs because dehydration and methanol removal reactions occur between methacrylic acid units and methyl methacrylate units within the molecule upon heating, and the resulting water and methanol become gases.

In order to overcome these drawbacks, for example, a terpolymer of an aromatic vinyl unit, methacrylic acid, and methyl methacrylate is heat-treated to form a six-membered cyclic acid anhydride unit represented by the formula (■): A heat-resistant copolymer formed in the molecule has been proposed (Japanese Patent Publication No. 49325/1983).

However, in this heat-resistant copolymer, the content of aromatic vinyl compound units needs to be 67% by weight or less, so it is possible to avoid a decrease in melt flowability, and therefore easy processability is avoided. It is unsuitable for the required applications such as foamed sheets, two-wheeled stretched sheets, and sheet molded products.

In addition, a copolymer containing methacrylic acid units and its acid anhydride units, which is mainly composed of monomer units of either alkyl methacrylate or styrene, has been proposed (Japanese Patent Laid-Open No. 85184/1984). However, using only either alkyl acrylate or styrene as a monomer unit cannot satisfactorily improve all physical properties such as heat resistance, mechanical strength, moldability, and water absorption.

Furthermore, a polymer mainly composed of methacrylic acid units and containing 50% by weight or more of six-membered cyclic acid anhydride units derived therefrom has also been proposed (JP-A-58
-71928), although it has been improved in terms of heat deformability, it has low melt flowability and poor moldability. In particular, when making a foam sheet and deep drawing molded product, the low strength causes cracks to occur on the surface of the molded product, making it unusable for practical use.

(What the invention is trying to solve! II) The present invention has excellent heat deformation resistance and thermal stability, has high mechanical strength, and has good processability, and can be used for foam sheets and foam sheets for thermoformed products. The purpose of this invention was to provide a transparent heat-resistant copolymer mainly composed of an aromatic vinyl compound that has excellent properties when used in

(Means for Solving the Problems) The present inventors have conducted intensive studies to develop a styrenic copolymer that has excellent heat resistance and mechanical strength in addition to the favorable physical properties of polystyrene. , (A) styrene unit, (B) α-methylstyrene unit, (C) methacrylic acid unit, (b) methyl methacrylate unit, (E) six-membered cyclic acid anhydride unit, and (F) general formula (I ): (wherein, 2 and mSn are integers of 1 to 20, R1, R
o, R3, R4 are hydrogen, methyl group, cyclohexyl group,
Alternatively, it is a phenyl group, at least one of which is an alkyl group having 2 to 5 carbon atoms. ) It has been discovered that a copolymer having a randomly arranged molecular structure in which the structural units represented by This led to a wealth of inventions.

That is, the present invention includes: (A) 70 to 90 mol% of styrene units, (B) 5 to 20 mol% of α-methylstyrene units, (C> 1 to 15 mol% of methacrylic acid units, (D) methyl methacrylate 1 to 25 mol% of units, and (E) 0.6-membered cyclic acid anhydride units.
5 to 1.5 mol%, CF) following - general formula (1) (wherein, 2, m% n is an integer of 1 to 20, R1, R
x, R3% R4 is hydrogen, methyl group, cyclohexyl group, or phenyl group, and at least one
One is an alkyl group having 2 to 5 carbon atoms. ) It is a styrenic polymer consisting of a structural unit represented by (F) a structural unit represented by general formula (1), (A) a styrene unit, (B) an α-methylstyrene unit, and (C) methacryl. The molar ratio of the acid unit, (D) methyl methacrylate unit, and (E) six-membered cyclic acid anhydride unit is (P)/((A) +
(B) +(C) +(D) +(1ri) -0
,006 to 0°000006,
It is a random copolymer, 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), (D), (E), and (F) have a molecular structure in which each unit is randomly arranged, and among these, the (^) unit, that is, the styrene unit, is the copolymer. It improves the melt flowability of the composite and improves molding processability, and is particularly important for foam sheet molding, especially for controlling foam cells.

It is important that the content of this styrene unit is in the range of 70 to 90 mol%. When the styrene content is less than 70 mol%, there is a problem of poor melt fluidity.

Moreover, if it exceeds 90 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 20 mol%.

If the amount of α-methylstyrene units is less than 5 mol%, the improvement in heat resistance will not be sufficient, and if it exceeds 20 mol%, the thermal stability during thermoforming will be insufficient. , giving rise to problems.

It is important that the amount of component (C) of the present invention, ie, methacrylic acid units, is in the range of 1 to 5 mol%. If it is less than 1 mol %, the effect of improving heat resistance will not be sufficient, and if it exceeds 5 mol %, problems will arise, especially in foam sheet molding, due to insufficient sheet strength.

It is important that the component (D) of the present invention, that is, the methyl methacrylate unit, is in the range of 1 to 25 mol%. 1
If it is less than mol%, the mechanical strength and oil resistance of the foamed molded product will be weak and it will not be usable.

Moreover, if it exceeds 25 mol %, the molding processability will be significantly lowered, making it unsuitable.

It is important that the component ((2) of the present invention, that is, the six-membered cyclic acid anhydride unit represented by the following formula (■)) has a range of 0.5 to 1.5 mol %.

The six-membered cyclic acid anhydride unit, component (E), is derived from methacrylic acid by heating the copolymer of the present invention at high temperature (Japanese Patent Publication No. 61-4932).
(See Publication No. 5).

The quantitative determination of the six-membered cyclic acid anhydride unit (E) can be calculated from the measurement results of absorption values at 1800-' and 1760-' using an infrared spectrophotometer needle.

If the amount of six-membered cyclic acid anhydride units is less than 0.5 mol %, the effect of improving heat resistance is insufficient, which is a problem. Also, 1
．． If it exceeds 5 mol%, foam sheet molding, especially
This causes problems due to insufficient sheet strength.

Component (F) of the present invention, i.e., the following general formula (I): (wherein j!, m, n are integers of 1 to 20, R1, RR
, Rs % R4 is hydrogen, methyl group, cyclohexyl group, or phenyl group, and at least one of them
One has 2 to 5 carbon atoms. ) constituent unit (F)
It is a styrenic polymer consisting of a structural unit (F) represented by the following general formula (1), (A) a styrene unit, and (B)
) α-, methylstyrene unit, (D) methyl methacrylate unit, and (E) six-membered cyclic acid anhydride unit, the molar ratio is (F)/((A)+(B)+(C)+( It is important that D)+(!ri-0,006 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, it is undesirable that the glass transition temperature is significantly lowered and the cost increases.

The quantitative determination of the structural unit (F) represented by the general formula (1) 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.
, 51 ml (g) for 30 minutes under reduced pressure.

Using this polymer, JNR-GX manufactured by JASCO ■
13ONMR was measured using 270 under the following conditions.

Complete decoupling mode - 45 degree pulse, observation frequency - 67.8MH2, waiting time = 2.5 seconds, number of scans = ioo, ooo times, sample concentration - 10wt%, solvent - 1,1-tetrachloroethane (d2) v Sample tube = 10m.

Measurement temperature -120°C0 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 adjacent to the quaternary carbon in the long chain appeared at 33 pPm. Appears at 7 ppm. The presence of the structural unit (F) represented by the general formula (1) can be confirmed by the appearance of these peaks.

The quantitative determination of the structural unit (F) represented by the general formula (1) is based on 38 to 50 ppm derived from the methylene and methine groups of the structural units (A), (B), (C), (D), and (H). It is also calculated from the peak area ratio of 29.4 ppm to the total area of the peaks that appear.The calibration curve required for the calculation is the first one below.
It is created using a polymer polymerized under the composition and polymerization conditions shown in the table.

Table 1 It has 7 repeating units.

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

The random copolymer of the present invention has a reduction degree of 0.3 g/d at a temperature of 25°C in a chloroform solution of 0.3 g/d.
It is necessary to be in the range of 15 to 2.0 di/g.

If it is less than 0.15 dl/g, the mechanical strength will be low, and if it exceeds 2.0 dl/g, the moldability will be insufficient and industrial use will be restricted, which is not preferable.

As a method for manufacturing the resin of the present invention, (^) to (D)
When carrying out bulk polymerization or suspension polymerization of the monomer □ form of general formula (III) (wherein l, m, n are integers of 1 to 20, Rr,
Rt, 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. ) 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 it in the proportion of parts by weight and polymerize it, and then heat-treat the resulting copolymer at a high temperature.
A new desired copolymer can be produced.

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

The decomposition temperature of these organic peroxides indicates a half-life of 10 hours. It can be determined by repeatedly performing an experiment of sealing the glass tube in a nitrogen-substituted glass tube, immersing it in a constant temperature bath, and causing thermal decomposition 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.

In the present invention, this 10 hour half-life is 40 to 100
It is advantageous to use a 40'C
If it is less than 100"C, there is a risk of explosion during storage and handling, and if it exceeds 100"C, it takes a long time for polymerization, resulting in a significant drop 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 11 (-〇-) 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,
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-t-butyl-
4-methylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl) 〉Propionate, etc., as a flame retardant, for example, tri(2,4-
Examples include di-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, thermal stability, and processability, and has excellent mechanical strength especially when made into foam sheets and foam molded products. It is colorless and transparent, and can be used in various It can be suitably used as a molding material for products, especially a foamed molding material.

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): Dissolve 0.15 g of sample in 50 d of chloroform. 2
The number of seconds of flow is measured using a Cannon Fenske viscometer 50# at 5°C, 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 m and a density of 0.099 g/cc. A polystyrene foam was obtained. This sheet was subjected to repeated bending tests to evaluate its strength.

Thirty samples were subjected to a bending test along the circumference of a cylinder with a diameter of 50+eφ, and the number of samples that did not crack was expressed as a percentage.

Example 1 (Assembling of glass cell) Two tempered glass plates of 400 x 300 x 3 oa were combined,
The gap was adjusted using a vinyl chloride gasket, and a glass cell was prepared so that three cast plates could be obtained.

(Polymerization) 75.0 parts by weight of styrene (ST), 15.0 parts by weight of α-methylstyrene, 5.0 parts by weight of methacrylic acid (MAA), 5.0 parts by weight of methyl methacrylate (MMA). O! A polymerization reaction solution consisting of 0.80 parts by weight of the initiator shown outside the frame in Table 1 and 0.35 parts by weight of α-methylstyrene dimer was injected from the injection port of the cell, and heated in a hot bath at 60"C for 5 minutes. After polymerization for 2 hours, the polymerization was carried out in an oven at 110'C for 2 hours.The polymerization reaction rate was 98%.

Similar glass cell polymerization was performed 20 times, and the resulting cast plate was crushed and extrusion foam molded.

The results are shown in Table 2.

Neutralization titration of this copolymer, infrared spectroscopy needle and “C”
As a result of compositional analysis by NMR, the obtained polymer was
The precepts include 4.0 mol% of MMA units, 79.5 mol% of ST units, 12.0 mol% of α-methylstyrene units, 3.5 mol% of MAA units, and 1.1 mol% of six-membered cyclic acid anhydride units. , a structural unit represented by the following formula: 0.0075 mol%.

The reduced viscosity (ηsp/C) of this polymer was 0.98, and the cyclic strength of the foam molded product was 100%.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 using the monomer composition shown in Table 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 is suitable for use in foamed sheets. As a molded product, it can be used as food packaging containers heated in a microwave oven.

(1 other person)

Claims (1)

Scope of Claims: (A) 70 to 90 mol% of styrene units, (B) 5 to 20 mol% of α-methylstyrene units, (C) 1 to 15 mol% of methacrylic acid units, (D) Methyl methacrylate 1 to 25 mol% of units, and (E) 0.5 to 1.5 mol% of six-membered cyclic acid anhydride units, and (F) the following general formula (I): ▲Mathematical formulas, chemical formulas, tables, etc. are included▼( I) (where 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. ) It is a styrenic polymer consisting of the structural unit represented by the general formula (I), (F) the structural unit represented by the general formula (I), (A) styrene unit, (B) α-methylstyrene unit, (C) methacryl Acid unit, (D) Methyl methacrylate unit, (E)
The molar ratio with the six-membered cyclic acid anhydride unit is (F)/[(A)+(
B) + (C) + (D) + (E)] = 0.006 to 0.0
00006, 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.