JPH02272050A - Transparent thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain a transparent thermoplastic resin composition consisting of a methyl methacrylate-based copolymer, vinylic copolymer and rubber-based graft copolymer and excellent in heat and impact resistance. CONSTITUTION:A resin composition, consisting of (A) a copolymer, containing 40-90wt.% methyl methacrylate, 5-20wt.% maleic anhydride, 5-40wt.% styrene and 1-15wt.% 1-4C alkyl acrylate and having a styrene content of 100-300wt.% based on the maleic anhydride, (B) a vinyl cyanide/aromatic vinyl copolymer or methyl methacrylate/1-4C alkyl acrylate copolymer and (C) a copolymer prepared by grafting (C2) vinyl cyanide and an aromatic vinyl compound in the total amount of 20-70 pts.wt. onto (C1) 30-80 pts.wt. rubber-like polymer within the range so as to provide (18:82)-(25:75) weight ratio of the vinyl cyanide to the aromatic vinyl compound and having <=0.005 difference in the refractive index between the mixture of the components (A) with (B) and the component (C).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermoplastic resin that is transparent, has excellent impact resistance, and has good heat resistance, and is used as a molding material in the automobile field, electrical field, etc. The present invention relates to a composition.

(Prior Art) Conventionally, polystyrene resin, acrylonitrile-styrene resin (AS resin), polymethyl methacrylate resin (PMMA resin), polycarbonate resin (PC resin), etc. have been used as transparent resins.

In addition, so-called A
A resin that is transparent and has good moldability has been proposed using BS resin.

For example, in Japanese Patent Publication No. 39-8667, polymethyl methacrylate and a graft copolymer are blended, and in order to maintain transparency, an Al3S resin of 0.
Rubber latex of 1 am or less and rubber latex of O, lym or more are used at the same time.

However, the heat resistance is not necessarily sufficient, and because a graft copolymer with low heat resistance is blended, the resin composition also has low heat resistance.

Therefore, the following proposals have been made to improve heat resistance while maintaining impact resistance and transparency.

For example, Japanese Patent Publication No. 44-15903 describes that impact resistance can be improved by blending an acrylonitrile-α-methylstyrene-styrene copolymer with a graft copolymer using α-methylstyrene. has been done. However, this method has poor processability and
In addition, it is not fully usable because it easily yellows.

In addition, Japanese Patent Publication No. 63-54305 discloses, in order to improve heat resistance, a methyl methacrylate copolymer, a graft copolymer of acrylonitocryl-styrene on rubber,
and a highly heat resistant methacrylonitrile-styrene copolymer, but sufficient heat resistance cannot be obtained by using methacrylate trile alone.

Furthermore, Japanese Patent Publication No. 63-1964 describes improving the heat resistance of polymethyl methacrylate-I resin (PMMA resin), which is a transparent resin, but this resin alone has poor impact resistance. The melt index, which is a measure of moldability, is very small, resulting in poor workability.

(Problems to be Solved by the Invention) A transparent resin composition containing a graft copolymer based on a rubbery polymer has good heat resistance while maintaining excellent impact resistance and transparency. No resin composition has been obtained.

The present invention provides a thermoplastic resin composition that has excellent impact resistance and good heat resistance while maintaining a high degree of transparency by improving the heat resistance of methyl methacrylate resin. .

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors found that methyl methacrylate (hereinafter abbreviated as MMA)
By blending a polymer made by copolymerizing maleic anhydride (hereinafter abbreviated as MAH) and styrene (hereinafter abbreviated as ST) in a special range with a rubber-based graft copolymer, it becomes transparent and durable. It has been discovered that a resin with good heat resistance can be obtained while maintaining fli impact resistance, and the present invention has been completed.

That is, the present invention is; (1) A copolymer consisting of 40 to 90% by weight of methyl methacrylate, 5 to 20% by weight of maleic anhydride, 5 to 40% by weight of styrene, and 1 to 15% by weight of alkyl acrylate having 1 to 4 carbon atoms. A copolymer (
A), ■ Copolymer of vinyl cyanide and aromatic vinyl or copolymer of methyl methacrylate and alkyl acrylate having 1 to 4 carbon atoms (B), ■ Rubbery polymer 30 to 8
A graft copolymerized by graft copolymerizing vinyl cyanide and aromatic vinyl to 0 parts by weight so that the total amount is 20 to 70 parts by weight and the weight ratio of vinyl cyanide to aromatic vinyl is in the range of 18F82 to 25775. A composition comprising a copolymer (C), and further comprising [4](A) +(
The total of B) + (C) is 100 parts by weight, and the difference between the refractive index of the mixture of components (A) + (B) and the refractive index of component (C) is 0.005 or less. The present invention relates to a thermoplastic resin composition that is transparent and has excellent heat resistance.

The present invention will be explained in more detail below.

The transparent thermoplastic resin composition of the present invention has excellent heat resistance.
Basically (A) Methyl methacrylate maleic anhydride -
It is a composition consisting of each of the following components: styrene resin, (B) an acrylonitrile-styrene copolymer or methyl methacrylic 1/-toalkyl acrylate copolymer, and (C) a rubber copolymer.

■ The methyl methacrylate-maleic anhydride-styrene resin of component (A) is obtained by polymerizing MMA with MAII, St, and alkyl acrylate having 1 to 4 carbon atoms in a special blending ratio, and when MMΔ monomer is polymerized. Compared to , the heat distortion temperature increases by more than about 20"C while maintaining the brightness at an altitude of <(4).

In other words, the mixing ratio of the four components of MMA, MAH, S L, and alkyl acrylate having 1 to 4 carbon atoms is
Methyl methacrylate is 40 to 90% by weight, maleic anhydride is 5 to 20% by weight, styrene is 5 to 40% by weight, and alkyl acrylate having 1 to 4 carbon atoms is 1 to 15% by weight, and based on maleic anhydride. The proportion of styrene is 1
It is preferably in the range of 00 to 300% by weight.

If the methyl methacrylate content is less than 40%, the solubility of maleic anhydride in the monomer compound will be poor, polymerization will be difficult, and the properties of the methyl methacrylate resin will deteriorate.
I'll be killed. Furthermore, when the content of methyl methacrylate exceeds 90%, the improvement in heat distortion temperature is small.

When maleic anhydride is less than 5% by weight or styrene is less than 5% by weight, the improvement in heat distortion temperature is small;
If maleic anhydride exceeds 20% by weight, thermal decomposition of the polymer will be accelerated during injection molding, and silver streaks will likely occur on the surface of the molded product, which is undesirable.

If styrene exceeds 40% by weight, heat resistance will be poor.

Alkyl acrylate having 1 to 4 carbon atoms is 1 to 15% by weight
, preferably 1 to 5% by weight. If it is less than 1% by weight, the effect on thermal stability will be weak, and if it exceeds 5% by weight, heat resistance will be poor.

Examples of the alkyl acrylate having 1 to 4 carbon atoms include methyl acrylate, ethyl acrylate, and butyl acrylate.

Furthermore, the ratio of styrene to maleic anhydride is 10
If it is less than 0% by weight, the number of maleic anhydride-methyl methacrylate copolymerization chains increases, which accelerates thermal decomposition of the polymer during injection molding, which is not preferable. Also, the residual upper
This is not desirable.

When the ratio of styrene to 71 anhydride/inic acid is 300%, no change in heat distortion temperature is observed.If monomer remains in the copolymer, the plasticizing effect This is undesirable because it not only lowers the heat resistance but also causes the molded product to foam during molding. In particular, residual maleic anhydride is undesirable because it causes yellowing of the molded product.

Therefore, the residual monomer profile is 1, 5 for the copolymer.
It is not more than 1.0% by weight, preferably not more than 1.0% by weight.

This copolymer is polymerized by known bulk polymerization, solution polymerization, or emulsion polymerization, but bulk polymerization is preferable.

■ Component (B) is vinyl cyanide 15-40m1%
and 85 to 60% by weight of aromatic vinyl, or 85 to 99% by weight of methyl methacrylate and 1 to 15% by weight of alkyl acrylate-h having 1 to 4 carbon atoms.

In the case of a copolymer consisting of vinyl cyanide and aromatic vinyl, the proportion of vinyl cyanide is 15 to 40% by weight,
Preferably it is 18 to 25%.

If vinyl cyanide is less than 18% vinyl cyanide, chemical resistance will be poor, and if it exceeds 25% vinyl cyanide, when mixed with component (A), the range of transparency will be narrow and moldability will not be sufficient. do not have.

Examples of vinyl cyanide constituting the copolymer include:
Examples include acrylonitrile and methacrylate trile. Furthermore, examples of the aromatic vinyl include styrene, α-methylstyrene, and the like.

In the case of a copolymer consisting of methyl methacrylate and alkyl acrylate, the proportion of methyl methacrylate and alkyl acrylate having 1 to 4 carbon atoms is 85 to 99%, particularly 95 to 99%. A weighted percentage is preferred.

Alkyl acrylate having 1 to 4 carbon atoms is 1 to 15% by weight
, preferably 1 to 5% by weight. If it is less than 1% by weight, the effect on thermal stability will be weak, and if it exceeds 5% by weight, heat resistance will be poor.

Examples of the alkyl acrylate having 1 to 4 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, and among these, methyl acrylate is particularly preferred.

Polymerization of these copolymers can be carried out by known bulk polymerization, solution polymerization,
Polymerization is carried out by emulsion polymerization, but bulk polymerization is preferred.

Component (C) consists of 30 to 80 parts by weight of a rubbery polymer, preferably 30 to 60 parts by weight, vinyl cyanide and aromatic vinyl, and 20 to 70 parts by weight of vinyl cyanide and aromatic vinyl. This is a graft copolymer obtained by graft copolymerization such that the weight ratio of group vinyl is in the range of 18:82 to 25Nia5.

In particular, the weight ratio of vinyl cyanide and aromatic vinyl is preferably 18 to 25% by weight based on the total amount of vinyl cyanide and aromatic vinyl, and vinyl cyanide is less than 18% by weight. If so, chemical resistance etc. will be inferior,
If it exceeds 25% by weight, when mixed with the above component (A),
The transparent range is narrow and moldability is insufficient.

Examples of vinyl cyanide constituting the copolymer include:
Examples include acrylonitrile and methacrylate trile. In addition, examples of aromatic vinyl include styrene,
Examples include α-methylstyrene.

The rubbery polymer used in component (C) must have elastomer properties in order to improve the 11 impact resistance of the composition of the present invention. One factor that indicates the properties of this elastomer is the glass transition point (Tg).
It is preferable that the rubber-like polymer has a Tg of -30°C or less.

For example, examples of polymers having a Tg of -30'C or less include diene polymers such as polybutadiene, styrene-butadiene rubber, butadiene-isoprene rubber, polyisoprene, alkyl acrylate, and alkyl methacrylate polymers.

Examples of alkyl acrylates include ethyl acrylate, butyl acrylate, and ethylhexyl acrylate.

Further, like the diene type, a rubber polymer containing an alkyl acrylate and a comonomer such as butadiene, styrene, acrylonitrile, alkyl methacrylate, or a mixture thereof may be used.

Graft copolymers based on rubbery polymers are produced by graft polymerizing vinyl cyanide, aromatic vinyl, etc. in the presence of rubber in a water-soluble emulsion.

■The blending ratio of the resin composition is 10 to 70 parts by weight of component (A), preferably 20 to 50 parts by weight, and 20 parts by weight of component (B).
~50 parts by weight, preferably 30 to 50 parts by weight, 10 to 40 parts by weight of component (C), preferably 20 to 30 parts by weight, and the total of each component (A) to (C) is 100 parts by weight. parts by weight, and the difference between the refractive index of the mixture of components (A) + (B) and the refractive index of component (C) is 0.005 or less.

That is, in order for the molded article of the present invention to exhibit transparency, it is necessary that the difference between the refractive index of the mixture of components (A) + (B) and the refractive index of (C) be 0.005 or less. The proportions of each component are blended in consideration of the refractive index.

In order to ensure transparency with such a formulation, the following method is used.

For example, refractive index of component (A) = (n2ゝ) NA Amount of component (A): 8 parts by weight Refractive index of component (B); (0 sweet) NB Amount of acid component B): 8 parts by weight Refractive index of component (C): (n'') NC Determine the proportion of each component that satisfies the following: A+B+C= 1 00 . . (1) As a result, a transparent resin can be obtained.

For example, temporarily set ■ of component (C) to a predetermined amount,
By determining the ratio of components (A) and (B) from (1) and (2), a mixing ratio that ensures transparency can be obtained.

The method of blending each component is not limited to 'l), but can be done using known techniques such as mixing powders and granules with a Henschel mixer tumbler, etc., and melting the dirt with an extruder, kneader, or mixer. It can be blended by various methods, such as mixing, sequentially mixing other components into previously melted components, and directly molding the mixture with an injection molding machine.

The resin composition thus obtained is molded using an extrusion molding machine, an injection molding machine, etc., to obtain a molded product that is transparent and has crush resistance of 14i.

In addition, the molding temperature at this time is 250 to 310°C, preferably 260 to 290°C, in order to maintain transparency and prevent whitening of the molded product and joint seams from being noticeable.
It can be done with

The resin composition of the present invention consists of the above-mentioned components, but if necessary, antioxidants such as hindered phenols and phosphorus, ultraviolet absorbers, flame retardants, plasticizers, A lubricant, a stabilizer, an antistatic agent, a dye, a pigment, etc. can be added.

The present invention will be specifically explained by examples, but these are not intended to limit the present invention.

(Example) Reference example 1: MMA-MAI! -3 for the production of resin (A
-1) In a reaction tank, mix 800 parts by weight of methyl methacrylate, 50 parts by weight of maleic anhydride, 140 parts by weight of styrene, and 10 parts by weight of methyl acrylate, and to this, 6 parts by weight of lauryl peroxide, and n-octyl mercaptan. A monomer blend solution was prepared by adding 6 parts.

Separately, the size is 2.500X, 3,0001IIl++
A cell was prepared by fixing the outer periphery of two glass plates with a Tγ diameter of 6 mm with a flexible polyvinyl chloride resin gasket, and setting the interval between the glass plates to 1 m.

Into this cell, 501'11all]g was stirred under reduced pressure.
and degassed for 2 minutes. Monomer i of 11'lI
21 people make fi mixture and fill it.

Next, it was placed in a hot water bath at a temperature of 60 to 65°C and reacted for 18 hours, then kept in a hot air oven at a temperature of 105 to 110°C for 3 hours, left to cool to room temperature, and the glass plate was removed. Then I took out the resin.

The obtained sheet-shaped resin is crushed with a Cantermill,
This was made into a pellet using an extruder.

The refractive index (n'') of this polymer was 1.505.

Measurement of refractive index (n"): The refractive index of the polymer was measured by preparing a film and using an Atsube refractometer. (Measurement temperature: 25"C) Reference Example 2: MMA-MAH-3t[ Production of fat (A2
), 700 parts by weight of methyl methacrylate, 100 ffl maleic anhydride, styrene in a reaction tank.
190 parts by weight of methyl acrylate and 10 parts by weight of methyl acrylate were mixed, and 6 parts by weight of lauryl peroxide and 6 parts by weight of n-octyl mercaptan were added to prepare a monomer blend solution.

The following operations are similar to those in Reference Example 1, and MMA-
Resin (A-2) was obtained from MAH-3.

The refractive index (n'') of this polymer was 1.51.5.

Reference Example 3 Production of Niger raft copolymer (C-1), rubber latex 1.00 mixed with butadiene rubber latex having an average particle diameter of 0.15 μm and 0.30 μm in a ratio of 1:1.
0 parts (solid content equivalent: 40% by weight) and 1 part of the emulsifier disproportionated potassium rosin acid were charged into a polymerization tank, and the temperature was raised to 70°C in a nitrogen stream while stirring, to 600 parts of butadiene rubber. A mixed solution of 80 parts of acrylonitrile, 320 parts of styrene, 1.2 parts of cumene hydroperoxide, 1.0 parts of t-dodecyl mercaptan, 1.5 parts of sodium formaldehyde sulfoxylate, and ferrous sulfate (FeSOa' 711zO) ) 0
, and 500 parts of distilled water in which 0.3 parts of ethylenediaminetetraacetic acid/2Na salt were dissolved were added over 6 hours for polymerization.

After the addition was completed, stirring was continued for another 2 hours, and the zero polymerization rate after polymerization was 95%.

The resulting graft copolymer latex was coagulated with a dilute aqueous sulfuric acid solution, washed, dehydrated, and dried to obtain a white powder graft copolymer (C-1).

The refractive index (n'') of this polymer was 1.540.

Reference Example 4 Production of Niger raft copolymer (C-2), rubber latex prepared by mixing butadiene rubber latex with an average particle size of 0.15 μm and 0.30 μm in a ratio of 2:1 100
The same procedure as in the preparation of the graft copolymer (C1) was carried out except that 1 part (solid content 10'n 40 parts) was used, and 1 part of the graft copolymer (C-2) was used.

The refractive index (n”) of this polymer is 1.539 Met.

In the case of a solid, a solid film was prepared and the refractive index of each component was measured using an Atsube refractometer. In the case of a liquid, it was directly measured (measurement temperature: 25°C).

■Acrylonitrile-styrene resin; Acrylonitrile-styrene resin (B-1) (AN/SL ratio 20:8
0) Intrinsic viscosity (η) = 60d/g Refractive index (n!S): 1. 575 acrylonitrile-styrene resin (B-2) (AN/St ratio 23 near 7) Intrinsic viscosity [η) = 0.58 d/g Refractive index (n”): 1.574 ■Polymethyl methacrylate resin; Polymethyl methacrylate Resin (B-3) (Methyl acrylate 2% by weight) Intrinsic viscosity [η] = 45/g Refractive index (n: 1.491) Polymethyl methacrylate resin (B-4) (Methyl acrylate 4%) Limit Viscosity [η)-32d/g Refractive index (n”) F 1. 492 (The intrinsic viscosity of the polymer was measured at 30°C in methyl ethyl ketone solvent) 1 As MMA-MAII-3t resin, (A-1) 37.5 parts by weight as component B, (B -1) 37.5ffi quantity C
As a component, 25.0 parts by weight of (C-1) was pre-mixed with a Henschel mixer, and then an outer diameter of 35 m5
using a screw extruder with a cylinder temperature of 150
Melt blending was performed at ~250'C and Gui temperature of 200-250C to form pellets.

Next, each physical property was evaluated using a test piece obtained by injection molding under the following conditions.

Molding conditions of injection molding machine; cylinder temperature, 230-290'C mold temperature, 55
°C Note that the physical properties shown in the following Examples and Comparative Examples were measured by the following method.

■Transparency: Total light vA transmittance, a degree is JIS K-6714
Measured according to.

■Heating deformation temperature: Measured according to JIS K-6871.

■Izotsu impact strength; ASTM D-256Ckg ・c++/cm, /
Measurement 1 according to the method for thickness 1/4")
Measurements were made by changing the ratio.

■Moldability (flowability): As MFR (melt flow index), l5O
-1130 (g/10m1n; 200°c110kg)
Measured using a method based on

Cutting period iッ1 A pellet was prepared in which each component had the composition ratio shown in Table 1, and the following operations were performed in the same manner as in Example 1, and each physical property was evaluated and shown in the table.

Comparative Examples 1 to 3 A pellet with each component in the composition ratio shown in Table 2 was used, and the following operations were performed in the same manner as in Example 1, and each physical property was evaluated and shown in the table.

Comparative Examples 4 to 5 As component (B), methacrylonitrile-styrene resin (hereinafter referred to as M
(abbreviated as ANS resin) was used to make pellets at the composition ratio shown in Table 2, and the following operations were performed in the same manner as in Example 1.
Each physical property was evaluated and shown in the table.

Note that the intrinsic viscosity [η] and refractive index of the MANS resin are as follows.

Intrinsic viscosity [η)-3 (ld/g Refractive index (n1s): 1,579 (The intrinsic viscosity of the polymer is measured at 30°C in methyl ethyl ketone solvent.) Table 2 (Effects of the invention) According to the present invention, it is possible to obtain a thermoplastic resin that is transparent, has excellent impact resistance, and has improved heat resistance.

Claims (1)

[Scope of Claims] [1] A copolymer of 40 to 90% by weight of methyl methacrylate, 5 to 20% by weight of maleic anhydride, 5 to 40% by weight of styrene, and 1 to 15% by weight of alkyl acrylate having 1 to 4 carbon atoms. and a copolymer (A) in which the ratio of styrene to maleic anhydride is in the range of 100 to 300%, [2] a copolymer of vinyl cyanide and aromatic vinyl or a copolymer of methyl methacrylate and a carbon number of 1 to 4. Alkyl acrylate copolymer (B), [3] vinyl cyanide and aromatic vinyl in 30 to 80 parts by weight of a rubbery polymer, the total amount of which is 20 to 70 parts by weight, and vinyl cyanide and aromatic The weight ratio of group vinyl is 18
: 82 to 25:75, and the total of [4] (A) + (B) + (C) is 100
parts by weight, and the difference between the refractive index of the mixture of components (A) + (B) and the refractive index of component (C) is 0.005 or less, and is transparent and has excellent heat resistance. Resin composition.