DE1694471C3 - Thermoplastic masses - Google Patents

Description

The invention relates to the subject matter evident from the above claim.

In contrast to polyacrylonitrile, polymethacrylonitrile is an amorphous polymer and is therefore required not very high temperatures for deformation in the molten state, for example during 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 of the grafted polymeric component 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.

The grafted-on polymeric component of the graft copolymer B can contain, as ethylenically unsaturated monomers, those which undergo copolymerization with acrylonitrile using free-radical catalysts. Such monomers usually (but not always) contain olefinic methyl groups. Examples are Al-L ₁ -IIi; wii- / H. Athvlen. Propylene, butene !. Isobutene.

Pentene-1, hexene-1, 2-methylbutene-1, 2-methylpentene-1, 4-methylpentene-1, 2,4,4-trimethylpentene-1, octene, octadecene, cyclohexene and methylenecodohexene, 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 ether. Esters of fumaric acid, vinyl chloride and vinylidene chloride. The softening point of the composition according to the invention can be raised by subjecting up to 10 mol% of maleimide or a maleimide derivative, in particular an N-aryl maleimide, together with the methacrylonitrile in the preparation of component A to a copolymerization. A process for the preparation of N-aryl maleimides from primary aromatic amines in good yield is described in GB-PS 1041027 and in NL-PS 6607 185. Many different primary aromatic amines are available and give N-aryl maleimides which can be used as comonomers for the compositions of the invention. The aryl substituent is an aromatic hydrocarbon radical or a heterocyclic radical in which one or more of the hydrogen atoms can be replaced by other atoms or groups. Substituents containing active hydrogen atoms should, however, generally be avoided because they can interfere with the free radical catalyzed polymerization. Examples of aryl groups in which N-aryl maleimides can be present are, for. 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,

ι 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 no more than three rings,

wherein each of the substituents optionally present has no more than four carbon atoms. Examples of such olefins are styrene and n-methyl styrene. o-methylstyrene. m-methylstyrene, p-Me-

ethylstyrene, 2,5-dimethylstyrene, 1-vinylnaphthalene, p-acetamidostyrene, ar-dibromostyrene, 2-vinylthiophene, N-vinylcarbazole and 2-methyl-5-vinylpyridine.

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

The problem of achieving a homogeneous copolymer, which both methacrylonitrile as is also found in acrylonitrile, is linked to the higher molar ratio of methacrylonitrile or acrylonitrile to 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 comparing the ratio of the concentrations of the aromatic olefin and the nitrile to Adjusts the beginning of the reaction to such a value that the graft formed at the beginning is the desired one Composition having, whereupon additional amounts of the aromatic olefin (optionally together with some nitrile) at a rate is added, 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 in the NL-PS 6704344 described.

Suitable dienes for the rubber-like graft base are e.g. B. butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and chloroprene. Acrylonitrile and styrene are particular comonomers convenient, although a wide variety of other monomers can be used such as e.g. 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 should be used at low temperatures.

The compositions according to the invention can be produced by a process in which several polymerizations follow one another (sequence 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 process is carried out using suitable procedures for free radical polymerisation, expediently in block or in aqueous form 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 graze. The product of this 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. It is possible, however, that the grafted polymeric component may not be completely chemically bonded to the rubber is bound, but also contains polymer that is obtained by separate polymerization from the monomers is formed, this polymer being mixed with the rubber in a much more intimate manner than it can normally be obtained by mixing the previously prepared polymers.

The amount of rubber in the finished mixture is not the only factor that determines the toughness, it also depends on the amount of rubber on the compound Rubber-grafted component.

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 g'atti-r 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 used as thermoplastic raw materials in a mixture with any fillers or reinforcing materials, lubricants and stabilizers 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 objects that can be produced from the compositions according to the invention, are panels and outer housings for machines (such as motor vehicles, office machines and Household appliances) helmets, pipes for liquids and telephone receivers. The use of the compositions according to the invention, which have a high tensile strength in conjunction with a high rigidity and Possess toughness, allow a more economical use than the currently used products, since 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 prepared as follows: 200 g of methacrylonitrile, 600 cm ^{1 of} water, 1.0 g of potassium persulfate and 3.5 g of sodium dodecyl sulfate were placed in a 1 liter cup 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 coagulated and the precipitated polymer was washed and dried. It had a reduced viscosity of 4.1, a full and a '/, (, - Vicat softening point of 113 and 107 ° C, respectively, and an impact strength (unnotched) of 3.92 J / cm ² .

A Piropf copolymer of the type described in French patent 1475403! Was prepared from polybutadiene, acrylonitrile and isobutene as follows: 205 g of polybutadiene latex (containing 126 g of polybutadiene), 119.6 cm ^{3 of} acrylonitrile, 1.98 g of cumene hydroperoxide, 2.64 g of glucose , 0.264 g FeSO ₄ .7H ₂ O, 1.3 g Na ₄ P ₂ O ₇ - 10H ₂ O and 532 cm ³ of water were introduced into a 1-1 shaken. 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 so that a mixture containing 10% polybutadiene was obtained. The mixed latices were coagulated with aqueous calcium chloride, and the mixture was washed and dried. Pressing at 200 ° C gave a transparent disk with full and 1 /, "- Vicat softening points of 113 and 107 ° C, respectively, an impact strength of 0.745 J / cm ² and a yield stress of 8.05 kgf / mm ² .

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 varied amounts of octanethiol contained. The properties of the obtained poly (methacrylonitrile) were as follows:

Octanethiol

Solids content
in latex

Reduced
viscosity

0.95 cm ³
1.19cm ³
2.38 cm ³

24.8%
24.75%
24.12%

0.86
0.73
0.47

Then 0.205 g FeSO ₄

7H ₂ O 60 ° C the mixture was cooled. The 1.atex contained 26.62% solids, indicating that the graft copolymer contained 49.8% polybutadiene.

The polymethacrylonitrile arces and the graft copolymer latex 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 1475403 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 ^{3 of} water were added placed in a stirred 5-1 autoclave. The air was removed and replaced with nitrogen (the autoclave was added three times with nitrogen under a pressure of 7 kg / cm ² and ventilated). 399 cm ³ of acrylonitrile was added, and the pressurizing and venting was repeated. 240 cm ^{3 of} isobutene were then added and the autoclave was shaken at 100 movements / min for 1 hour at 60 ° C.

and 1.03 g

Na ₄ P ₂ O ₇ K) H ₂ O was added. Shaking was continued and, after one hour, 0.205 g of FeSO ₄ · 7H ₂ O and 1.03 g of Na ₄ P ₂ O ₇ · 10H ₂ O were added again. The same amounts were added again after 2 hours. After 3.67 hours at

Notched impact yield strength stress

0.86
0.73
0.47

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

7.55 kgf / mm ² 7.5 kgf / mm ^: 7.05 kgf / mm ²

Example 3

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 ^{3 of} acrylonitrile, 1.40 cm ^{3 of} styrene, 1.05 g of cumene hydroperoxide, 1.4 g of glucose and 650 cm ^{3 of} 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 · 10H ₂ O (0.7 g) in 50 cm ^{3 of} water was added to achieve a reasonable rate of polymerization. The polymerization was carried out at approximately 60 ° C and 20.7 cm ^{3 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 mixed polymer, 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 mixed graft polymer which had been prepared according to the procedure of Example 2 were prepared mixed on a steam-heated two-roll mill with rolls 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 A1 ₂ (SO ₄ ) ₃ 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 / mm ^{2 for} 5 minutes, with one

transparent disk with a notched impact strength of 0.19 J / cirr and a tensile strength wedge of 6.5 kgf / mm ^{: was} obtained.

In the previous examples, the reduced Yhuosity at a concentration of 0.i% measured in dimethylformamide at 25 ° C, and the tensile strength and impact strength were as in Jcr size described measured.

The impact strength tests with uncapped samples were carried out at 20 ° C. with a sample 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 '). The resulting value (expressed in joules / cm ³ ) 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

owned a · ■ !? "-Notch 2. 5 mm deep (pointed cnra dius of>, 25 mm) in the center of an edge. It was supported by two straps that were 50 mm apart Wiesen, supported and was centrally located on the Karitr the one opposite the notch: pushed with a pendulum that fell from a height of 30 cm, warped it had a greater energy than was required to break the sample. From the rest of the energy of the pcde ice was the energy needed to break dci Specimen required was calculated and divided by the cross-sectional area of the specimen at the notch The value obtained (expressed in joules / cmr) stell represents the energy required to break the material.

The tensile strength was measured at + 20 ° C. using 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 over the center of the sample was reduced to 9 mm ² by machining two slots (radius of curvature 31 mm) opposite one another in the long edges so that the narrowest point of the sample was 3 mm. A tensile stress sufficient to extend it at a rate of 12.7 mm / min was then applied to the sample, and the stress at the yield point was measured.

Claims (1)

Claim: Thermoplastic mass made of: A: a methacrylonitrile homopolymer or copolymer with, if appropriate, up to 10 mol% one or more polymerized monoethylenically unsaturated monomers and B: a graft copolymer consisting of a graft and a rubber-like one Graft base consists and by grafting the graft on the rubber-like The graft has been made, the graft (a) 60-85 mol% acrylonitrile units and corresponding (b) 15-40 mol% of units of one or more Contains ethylenically unsaturated monomers and the rubbery graft ( _c ) 40-100 MoI- ^ e at least one conjugated diene monomer and (d) 0-60 mol% of at least one other ethylenically unsaturated monomer contains the thermoplastic composition being 1-50% by weight of the rubbery one Contains graft base.