DE1694471B2 - Thermoplastic masses - Google Patents

Description

The invention relates to the from the above patent i> claim apparent object.

In contrast to polyacrylonitrile, polymethacrylonitrile is an amorphous polymer and is therefore required no very high temperatures for deformation in the molten state, for example with the 4 « Injection molding or extrusion. In contrast to polyacrylonitrile, which is subject to degradation before it melts, it is not necessary in the case of polymethacrylonitrile to incorporate other monomers in order to achieve crystallinity to eliminate. As a molding compound, however, it suffers from the fact that it is brittle.

In contrast, the masses described in the preceding claim are not brittle, but nevertheless of excellent transparency. This is surprising because the grafted polymeric composite is so nente and the methacrylonitrile homopolymer or copolymer have considerable differences from one another. Nevertheless, components A and B of the composition according to the invention are surprising compatible, so that they can be processed into molded articles that are not only exceptional Impact resistance, but also have high transparency.

Component A is preferably a homopolymer. bO

The grafted-on polymeric component of the graft copolymer B can be ethylenically unsaturated Monomers contain those which undergo copolymerization using free radical catalysts enter with acrylonitrile. Such monomers usually (but not always) contain olefinic ones Methyl groups. Examples are alkenes, such as. B. ethylene, propylene, butene-1, isobutene, Pentene-1, hexene-1, 2-methylbutene-1, 2-methylpentene-1, 4-methylpentene-l, 2,4,4-trimethylpentene-l, Octene, octadecene, cyclohexene and methylenecyclohexene, conjugated aromatic olefins, such as. B. butadiene and norbornadiene, esters of acrylic and methacrylic acid, such as. B. methyl, ethyl, n-butyl and 2-ethylhexyl acrylate and methyl and n-butyl methacrylate, Vinyl esters such as B. vinyl acetate, vinyl ethers, such as. B. methyl and ethyl vinyl ethers, esters of fumaric acid, vinyl chloride and vinylidene chloride.

The softening point of the composition according to the invention can be raised by up to to 10 mol% maleimide or a maleimide derivative, in particular an N-aryl maleimide together with the Methacrylonitrile subjected to copolymerization in the preparation of component A. A Process for the preparation of N-aryl maleimides from primary aromatic amines in good yield is in GB-PS 1041027 and in NL-PS 6607 185 described. Many different primary aromatic amines are available and give N-aryl maleimides, which can be used as comonomers for the compositions according to the invention. The aryl substituent is an aromatic hydrocarbon radical or a heterocyclic radical in which one or several of the hydrogen atoms can be replaced by other atoms or groups. Substituents that However, active hydrogen atoms are generally to be avoided as they are produced by free radicals can interfere with catalyzed polymerization. Examples of aryl groups in which N-aryl maleimides may be present, are z. B. Phenyl, 4-Bipheny-IyI, 1-naphthyl, all mono- and dimethylphenyl isomers, 2,6-diethylphenyl, 2-, 3- and 4-chlorophenyl, 4-bromophenyl and other mono- and dihalophenyl isomers, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, 4-n-butylphenyl, 2-methyl-4-n-butylphenyl, 4-benzylphenyl, 2-, 3- and 4-methoxyphenyl, 2-methoxy-5-chlorophenyl, 2-methoxy-5-bromophenyl, 2,5-dimethoxy-4-chlorophenyl, 2-, 3- and 4-ethoxyphenyl, 2,5-diethoxyphenyl, 4-phenoxyphenyl, 4-methoxycarbonylphenyl, 4-cyanophenyl, 2-, 3- and 4-nitrophenyl, and methylchlorophenyl (2,3-, 2,4-, 2,5 and 4,3 isomers). The N- (o-substituted phenyl) maleimides are generally less colored than the other isomers or the unsubstituted compounds; they are therefore preferred when relatively colorless products are desired. It has also been found that norbornene and its derivatives Increase the softening point, but the interpolymerization of these compounds with methacrylonitrile takes place very slowly.

If one or more of the copolymerizable monomers which is a conjugated aromatic olefin in component A or in the grafted polymeric constituent of component B, then it is very desirable to ensure that the copolymer formed is a homogeneous copolymer. The conjugated aromatic olefin is selected from those of the formula CH ₂ : CR · Ar and also from acenaphthylene, indene and coumarone. In this formula, R is hydrogen or methyl and Ar is an optionally ring-substituted radical of aromatic character with not more than three rings, each of the optionally present substituents having not more than four carbon atoms. Examples of such olefins are styrene, a-methylstyrene, o-methylstyrene, m-methylstyrene, p-Me-

ethylstyrene, 2,5-dimethylstyrene, l-vinylnaphthalene, p-acetamidostyrene, ar-dibromostyrene, 2-vinylthiophene, N-vinyl carbazole and 2-methyl-5-vinyl pyridine.

The expression "homogeneous copolymer" used in the following means a copolymer meant in which the polymer molecules formed at the beginning of the reaction are essentially the same have average compositions like those formed later.

The problem of achieving a homogeneous copolymer, which both methacrylonitrile as is also found with acrylonitrile, is with the higher molar ratio of methacrylonitrile or acrylonitrile linked to the aromatic olefin in the desired product There are generally none Difficulty when the molar ratio of the nitrile to the conjugated aromatic olefin is one or one is smaller. A homogeneous product can be obtained by looking at the ratio of the concentrations of the aromatic olefin and the nitrile at the beginning of the reaction to such a value, that the graft formed at the beginning has the desired composition, whereupon more Amounts of the aromatic olefin (optionally along with some nitrile) at a rate which is determined by the rate of polymer formation, so that the ratio of the concentration of the aromatic olefin to the nitrile in the reaction mixture remains at the desired initial value.

The present invention relates to thermoplastic compositions comprising a methacrylonitrile polymer in Mixture with a graft copolymer, with acrylonitrile being the predominant in the latter is a monomeric component in the grafted-on polymeric component of the graft copolymer. Particularly suitable acrylonitrile graft copolymers of this type are described in FR-PS 1475403 and NL-PS 6704344.

Suitable dienes for the rubber-like graft base are e.g. B. butadiene, isoprene, 2,3-dimethylbutadiene, Piperylene and chloroprene. Acrylonitrile and styrene are particularly useful comonomers, although a wide variety of other monomers can be used, such as B. those above as examples of ethylenically unsaturated Comonomers were listed. Diene homopolymers (such as polybutadiene) and copolymers with a low proportion of comonomer have low glass transition temperatures and can therefore be preferred especially if the product is to be used at low temperatures.

The compositions of the invention can be prepared by a process in which several polymerizations successive (sequential polymerization). In this process, the monomers for the grafted-on polymeric component of the graft copolymer by free radical catalysis polymerized in the presence of the diene rubber. The procedure is carried out using appropriate working practices carried out for free radical polymerization, expediently in the block or in aqueous Suspension or emulsion. A similar emulsion process or a stereospecific process can be used be used to produce the diene rubber. The graft copolymer can then be used as a latex used or isolated from the polymerization medium, freed from residual monomers and dried will. The product of this sequential polymerization

with acrylonitrile is mixed with the methacrylic polymer (component A), whereby a tough, hard and a transparent product is obtained. Suitable methacrylonitrile polymers are, for example, homogeneous Copolymers with conjugated aromatic olefins.

The resulting products thus partly consist of a material that is usually known as Graft copolymer is referred to. However, it is possible that the grafted polymeric component is not completely chemically bound to the rubber, but also contains polymer that is formed by separate polymerization from the monomers, this polymer with the rubber is mixed in a much more intimate manner than would normally be done by mixing the previously prepared Polymers can be obtained.

The amount of rubber in the finished mixture is not the only factor that determines the toughness, this also depends on the amount of the component grafted onto the rubber.

The thermoplastic composition of the present invention contains 1-50% by weight of the diene rubber.

Compounds that contain less than 25% of the rubber are particularly hard and scratch-resistant materials with high impact resistance. There is obviously a smooth transition of properties, but Compounds containing at least 20% (preferably no more than 40%) of the rubber usually hard materials with very high impact resistance.

The compositions according to the invention can be mixed with any fillers or reinforcing materials, Lubricants and stabilizers are used as thermoplastic raw materials Manufacture items that require good impact resistance. Your toughness in connection having high strength and high softening point is very advantageous. For example, the masses be extruded into sheets or tubes, and the sheets can optionally be embossed with rollers or deformed by pressing, drawing or vacuum forming. The compositions can also be deformed by pressing or injection molding. Examples of articles resulting from the inventive What can be mass produced are panels and outer housings for machines (such as motor vehicles, office machines, and household appliances) crash helmets, pipes for liquids and telephone receiver. The use of the compositions of the invention that have high tensile strength in connection with a high stiffness and toughness, allow a more economical Use than the products currently in use, as thinner workpieces serve the same purpose to serve. The advantageous physical properties of the compositions also allow them to be used to use technical applications in which plastic was previously unsuitable.

The following examples illustrate the invention.

example 1

Polymethacrylonitrile was made as follows: 200 g methacrylonitrile, 600 cm 'water, 1.0 g potassium persulfate and 3.5 g of sodium dodecyl sulfate were placed in a 1-liter shaking autoclave. The air was removed and replaced with nitrogen. The poly

merization was carried out for 18 hours at 60 ° C., a polymethacrylonitrile being obtained as latex in 99% yield, calculated on the solids content. A portion of the latex was aggregated and the precipitated polymer was washed and dried. It had a reduced viscosity of 4.1, full and 1/1 Vicat softening points of 113 and 107 ° C., respectively, and an impact strength (unnotched) of 3.92 J / cm ² .

A graft copolymer of the type described in French patent specification 1475 403 was prepared from polybutadiene, acrylonitrile and isobutene as follows: 205 g polybutadiene latex (containing 126 g polybutadiene), 119.6 cm 'acrylonitrile, 1.98 g cumene hydroperoxide, 2.64 g glucose , 0.264 g of FeSO ₄ · 7H ₂ O, 1.3 g of Na ₄ P ₂ O ₇ · K) H ₂ O and 532 cm ^{3 of} water were placed in an IL shaking autoclave. The air was removed and replaced with nitrogen and 71.8 cm ^{3 of} isobutane was added. The mixture was shaken at approximately 20 ° C for 1.5 hours and then at 60 ° C for 17.5 hours. The latex obtained contained 26.7% solids.

The polymethacrylonitrile latex and the graft copolymer latex were mixed together to form a mixture containing 10% polybutadiene was obtained. The mixed latices were coagulated with aqueous calcium chloride and the mixture was blended washed and dried. When pressed at 200 ° C, it gave a clear disk with a full and a '/, "- Vicat softening point of 113 or 107 ° C, a notched impact wedge of 0.745 J / cnr and a yield stress of 8.05 kgf / mnr.

Example 2

Polymethacrylonitrile was prepared according to the procedure of Example 1, with the difference that the Polymerization was carried out for 16 hours and the reaction mixture contained various amounts of octanethiol. The properties of the obtained polymethacrylonitrile were as follows:

Octanethiol

Solids content
in latex

Reduced
viscosity

0.95 era '
1.19 cm ¹
2.38 cm- '

24.8%
24.75%
24.12%

0.86
0.73
0.47

The mixture was cooled to 60 ° C. The latex contained 26.62% solids which indicated the graft copolymer Contained 49.8% polybutadiene.

The polymethacrylonitrile latices and the graft copolymer latices were mixed so that mixtures containing 10% polybutadiene were obtained. The mixtures were made using of 1.5 volumes of 0.75% aqueous calcium chloride at 75 ° C coagulated, and the mixtures were washed three times with water at 60 ° C and dried. They made translucent Compacts with the following properties:

Reduced viscosity of the polymethacrylonitrile

A graft copolymer of the type described in French patent specification 1,475,403 was prepared from polybutadiene, acrylonitrile and isobutene as follows: 586.3 g of polybutadiene latex (containing 360 g of polybutadiene), 8.22 g of glucose, 6.16 g of cumene hydroperoxide and 1675 cm 'of water were placed in a 5 liter stirred autoclave. The air was removed and replaced with nitrogen (the autoclave was spiked three times with nitrogen at a pressure of 7 kg / cnr and vented). 399 cm 'of acrylonitrile was added and the pressurization and venting repeated. 240 cm 'of isobutene were then added and the autoclave was shaken at K) 0 motions / min for 1 hour at 60 ° C. Then 0.205 g of FeSO ₄ 7H ₂ O and 1.03 g of Na ₄ P ₂ O ₇ · K) H ₂ O were added. Shaking was continued and after one hour another 0.205 g FeSO ₄ 7H _: O and 1.03 g Na ₄ P ₂ O ₇ · K) H ₂ O were added. The same amounts were added again after 2 hours. Stressed after 3.67 hours at notched impact yield strength

0.30 J / cm ²
0.30 J / cm ²
0.20 J / cm ²

Example 3

7.55 kgf / mnr 7.5 kgf / mm ² 7.05 kgf / mm-

The polymethacrylonitrile latex of Example 2 with a reduced viscosity of 0.86 was mixed with a graft copolymer of the type described in Dutch patent 6,704,344, which had been prepared from polybutadiene, acrylonitrile and styrene as follows. 130.4 g of polybutadiene latex (containing 80 g of polybutadiene), 49.65 cm 'acrylonitrile, 1.40 cm' styrene, 1.05 g cumene hydroperoxide, 1.4 g glucose and 650 cm 'water were placed in a reaction vessel. The air was removed and replaced with nitrogen. A sufficient mixture of FeSO ₄ 7H ₂ O (0.14 g) and Na ₄ P ₂ O ₇ · K) H ₂ O (0.7 g) in 50 cm 'of water was added to achieve a reasonable rate of polymerization . The polymerization was carried out at approximately 60 ° C and 20.7 cm of styrene was added at a rate proportional to the rate of polymerization. After 3 hours, the polymerization was terminated by adding 0.5% sodium dimethyldithiocarbamate. The latex was 14.87% solids, indicating that the graft copolymer contained 61.4% polybutadiene.

The mixture produced in this way contained 10% polybutadiene and was isolated as described in Example 2. It gave slightly fogged compacts with a yield stress of 8.00 kgf / mm ² .

Example 4

A sample of a methacrylonitrile copolymer, which contained 97% by weight of methacrylonitrile and 3% by weight of methyl methacrylate and had a reduced viscosity of 0.52, and an acrylonitrile / isobutene / polybutadiene graft copolymer which had been prepared according to the procedure of Example 2 were prepared mixed on a steam-heated two-roller mill with rollers 5.1 cm in diameter and 15.2 cm in length at 170-180 ° C. The mixtures were coagulated using 1.5 volumes of 0.5% aqueous Al ₂ (SO ₄ ) at 75 ° C, and the mixture was washed three times with water at a temperature of 60 ° C and then dried. The mixtures were stabilized with 1% 2,6-di-t-butyl, 4-methylphenol and 0.5% dilauryl thiodipropionate.

The obtained crepe was pressed at 160 ° C and 31.5 kgf / mnr for 5 minutes, with one

transparent disk having an impact strength of 0.19 J / cm ² and a tensile strength of 6.5 kgf / mm ^{2 was} obtained.

In the previous examples, the reduced viscosity was at a concentration of 0.5% measured in dimethylformamide at 25 ° C, and the tensile strength and impact strength were as in the sequence described measured.

The impact tests with unnotched specimens were carried out at 20 ° C. with a specimen 0.9 cm wide and 0.3 cm thick, which rested horizontally (with the narrow surface facing up) on two supports that were 3.8 cm apart exhibited. The sample was then pushed horizontally at the center of the wider surface by a moving pendulum which fell from a height of 30 cm, with a greater energy than was necessary to break the sample. The energy required to break the sample was calculated from the remaining energy of the pendulum and divided by the effective volume (V ₉ X 3.8 X 0.9 X 0.3 cm ³ ). The resulting value (expressed in joules / cm ^J ) represents the energy required to cause fractures in the material.

The impact strength test with notched specimens was carried out at 20 ° C with a specimen of 60 mm length, 6.5 mm wide and 3 mm thick. The sample had a 45 ° notch 2.5 mm deep (tip radius 0.25 mm) in the center of an edge. It was from two beams that were 50 mm apart, supported and was pushed with a pendulum centrally on the edge> opposite the notch, that fell from a height of 30 cm, with a greater energy than that used to break the Sample was required. The remaining energy of the pendulum became the energy needed to break the pendulum

ι »sample was required, calculated and divided by the cross-sectional area of the sample at the notch. The value obtained (expressed in joules / cm ² ) represents the energy required to break the material.

π The tensile strength was measured at + 20 ° C with a probe 76 mm long and 14 mm wide, which had been worked out from a pressed sheet 3 mm thick. The cross-sectional area across the center of the sample was reduced to 9 mm ²

2 «by two slots (radius of curvature 31 mm) facing each other opposite in the long edges were worked out, so that the narrowest point of the Sample was 3 mm. Tensile stress was then applied to the sample sufficient to hold it in place

r> to extend the speed of 12.7 mm / min and the tension at the yield point was measured sen.

Claims (1)

Claim: Thermoplastic mass made of: A: a methacrylonitrile homo- or mixed po- "> lymerisat with optionally up to 10 mol% of one or more polymerized monoethylene unsaturated monomers and B: a graft copolymer consisting of a graft and a rubber-like «· Graft base consists and by grafting the graft on the rubber-like The graft has been made, the graft (a) 60-85 mol% of acrylonitrile units and r> corresponding (b) 15-40 mol% of units of one or more ethylenically unsaturated monomers contains and the rubbery graft - '< > (c) 40-100 mole percent of at least one conjugated Diene monomers and (d) 0-60 mol% of at least one other ethylenically unsaturated monomer contains> "> where the thermoplastic mass is 1-50% by weight of the kaulschuk-like Contains graft base.