DE2045742B2 - TRANSPARENT, IMPACT TOUGH MOLDING - Google Patents

Description

Weight ratio 60:40 to 90:10 on 90 of the French patent 1 321 146 are bi-

up to 30 percent by weight of a Ka chuks with ₂ o nary mixtures with increased impact strength

a glass temperature below -30 ° C, polymethyl methacrylate or styrene / acrylonitrile-Ce

where the parts by weight add up to 100 polymers with graft copolymers described,

and the difference between the refractive Since these mixtures are not transparent, however,

index of component C and the refractive index _{, it was} not immediately obvious to use graft co-

index of the mixture of component A and _a5 polymers also to increase the impact strength

B is less than 0.005, and of transparent blends to be used. To-

D) optionally conventional additives in quantitative minimum, this solution does not result directly gen up to 50 ° / _0th by combining the pre-published teachings

ex post as the impact strength improvement before.

30 hard polymers once by mixing with

Rubbers and on the other hand by grafting

The subject of the invention and transparent, impact rubbers are regarded as equivalent (see

tough, thermoplastic molding compounds from a hard, e.g. Houben-Weyl, vol. 14/1. 1961, p. 338,

Methyl methacrylate polymer A, a hard Sty or plastic dictionary, 1967, p. 13).

rol / acrylonitrile polymer B and a soft 35 The present invention relates to molding

Graft copolymer C of styrene and acrylonitrile on mass, consisting of a mixture of

a rubber. A) 20 to 80 parts by weight of a methyl methacrylate

Methyl methacrylate polymers and styrene / acrylic polymers from 90 to 100 percent by weight

nitnl copolymers are hard and transparent methyl methacrylate and 10 to 0 percent by weight

Plastics that are relatively brittle, 40 _{dnes A} | _ky i _a crylate with 1 to 8 carbon atoms

so that they j _m Alkvlrest with stronger mechanical stress
break.

The object of the present invention was to B) 1 ° ^{to 50} parts by weight of a «; Styrene acrylonitrile

basic, transparent, thermoplastic molding compounds polymer made from 70 to 90 percent by weight styrene

to develop with high impact strength. For those 45 ^{and 30 to} Ό percent by weight acrylonitrile.

Plastics that have high mechanical strength and q 10 to 50 parts by weight of a graft copoly-

Combine water-tightness in a large amount of 10 to 70 percent by weight styrene

Requirement. A possible solution for this problem _and acrylonitrile in a weight ratio of 60:40

is the production of plastics based on up to 90:10 on 90 to 30 percent by weight of one

Polycarbonates or polyamides. These substances are 50 rubbers with a glass temperature below

but relatively expensive. _of ^ 30 ⁰ C and

There has also been no lack of attempts to transpa- ^ _x,. ........., ~,.

Rent, impact-resistant molding compounds based on acrylic ^D) given all the usual additives in quantities

nitrile / butadieii / methyl methacrylate / styrene. ^{b! s m 5} - "> ·

Up to now, however, the approach has been almost exclusively from 55. The parts by weight should add up to 100

Terpolymers from. It is about and the difference between the refractive index of the

Mixtures of styrene / acrylonitrile / methyl methacrylate soft component C and the refractive index

Polymers with graft polymers of styrene / the mixture of the two hard components A and

Acrylonitrile / methyl methacrylate on polybutadiene chewing B are less than 0.005.

chuke. These production methods are, for example, 60 The hard component A is preferably poly-wise in German Offenlegungsschrift 1520631, methyl methacrylate; however, they are also copoly-1 569 385, 1 569 585 and 1 900135. merisate of methyl methacrylate with up to 10 Ge-Im In contrast to these terpolymerizations, weight percent of an alkyl acrylate having 1 to 8 carbons is the same Production of the components of the atoms of the invention in the alkyl radical, for example methacrylate appropriate mixture, where only a maximum of two 65 and butyl acrylate can be used. Through the installation Monomers are copolymerized, technically one of the alkyl acrylate in the methyl methacrylate polymer fold. In addition, one is in aligning the sat will be the flowability of component A and Refractive indices (especially when there are fluctuations in the mixtures as well. Methylmeth-

Acrylate polymers can be prepared by bulk, solution or bead polymerization using known methods getting produced. Methyl methacrylate polymers, especially those with only a low alkyl acrylate content, have a high heat resistance.

The hard component B is a copolymer of 70 to 90 percent by weight of styrene and 30 to 10 weight percent acrylonitrile. These copolymers can be produced by all known processes , for example by bulk, solution, suspension or emulsion polymerization. Styrene / Acrylonitrile copolymers have good flowability. This property is used accordingly high content of component B also on the inventive transfer deletion.

The soft component C is a graft copolymer of 10 to 70, preferably 20 to 60 percent by weight of a mixture of styrene and acrylonitrile in a weight ratio of 60:40 to 90:10 to 90 to 30, preferably 80 to 40 percent by weight of a rubber with a glass temperature below - 30 ^° C. The rubbers used must have elastomeric properties so that they bring about an improvement in the impact strength of the mixture according to the invention. A measure of this elastomeric property is uie glass transition temperature according to KH Illers and H.Breuer, Kc.loid-Zeitschrift 176, p. 110, 1961. The following are, for example, natural rubber; Diene polymers, vvie polybutadiene, polyisoprene, copolymers of butadiene with isoprene. Styrene or acrylonitrile; Acrylic ester polymers are preferred which contain at least 30 percent by weight of an alkyl acrylate with a maximum of 8 carbon atoms in polymerized form in the alkyl radical. Preferred acrylic esters are ethyl acrylate, butyl acrylate and ethylhexyl acrylate. Examples of comonomers are butadiene and styrene. Acrylonitrile or vinyl ether, or mixtures thereof, are suitable. The acrylic ester polymers can optionally be partially crosslinked by copolymerizing comonomers containing at least two double bonds. The graft copolymer C is prepared by polymerizing a mixture of styrene and acrylonitrile in the presence of the rubber, preferably in an aqueous emulsion. There is an at least partial chemical linkage of the polymerizing monomers with the already polymerized rubber, the linkage probably taking place at the double bonds contained in the rubber.

The mixture should be 20 to 80, preferably 30 to 60 parts by weight of component A; 10 to 50, preferably 10 to 40 parts by weight of component 3 and 10 to 50, preferably 20 to 40 parts by weight of component C.

In addition to the A + B -} - C mixture, the molding compounds can contain up to 50% of the usual additives contain, for example, other compatible thermoplastics such. B. styrene / maleic anhydride copolymers; also fillers, dyes, stabilizers, lubricants and antistatic agents.

The mixing of the components and optionally of additives is preferably carried out in the melt: The components are vcrirbeitet at temperatures from 200 to 260 ⁰ C on extruders, rollers or kneaders. It is also possible to mix solutions or suspensions of the components and then remove the liquid.

An essential requirement for transparency of the molding compositions according to the invention is that the difference between the refractive index of the soft Component C and the refractive index of the mixture of the two hard components A and B. is less than 0.005. The refractive index of the mixture of hard components is calculated as the arithmetic mean of the refractive indices of the two individual components. requirement of it is

ίο, however, that the two hard components are compatible, d. H. are homogeneously miscible with one another in all proportions. With a given refractive index the soft component C becomes the refractive index of the hard component by suitable choice the ratio A: B adjusted.

In this way, transparent molding compositions are obtained by simply mixing the components of high impact strength, good heat resistance and satisfactory flowability.

The molding compositions according to the invention can be molded by injection molding or inflation, man it can be pressed, calendered or vacuum formed. They can be used anywhere where the toughness of conventional transparent plastics is insufficient; for example at Automobile taillights, see-through household appliances and toys or for advertising displays.

The parts and percentages given in the examples are based on weight.

The viscosity numbers // sp'C in [cm ³ / g] were in a 0.5 percent solution in chloroform (for A) or. measured in dimethylformamide (for B). The Vicat softening point in [ ^c Cj was determined according to DIN 53460, method B, in silicone oil. When determining the energy to break, the work of damage was measured in [cm · kp] in a biaxial puncture test on 1 mm thick round plates with a diameter of 50 mm. The plaques are injection molded at Massetemper.ituren of 240 ⁰ C. The refractive index // «was determined with an Abbe refractometer according to the method for measuring the erection indices in solid bodies (see Ullmanns Encyklopadie der technischen Chemie, Vol. 2/1, p. 486; editor W. Foerst; Urban & Schwarzenberg, Munich-Berlin, 1961). The limit bending stress in kp per cm ² was determined in accordance with DIN 53462.

Examples

The following components were used for the mixtures:
A ₁ polymethyl methacrylate (refractive index β = 1.492, viscosity number = 52);

A ₂ copolymer of methyl methacrylate and methyl acrylate 95.8: 4.2 (11 _D = 1.492, viscosity number = 52);

A ₃ copolymer of methyl methacrylate and methyl acrylate 92.6: 5.1 (n _D = 1.492, viscosity number = 52);

A ₄ copolymer of methyl methacrylate and butyl acrylate 94.9: 5.1 (n _D = 1.492, viscosity number = 52);
B copolymer of styrene and acrylonitrile 75:25 (n _D = 1.574, viscosity number = 104);
C ₁ graft copolymer of 25% styrene and acrylonitrile (70:30) to 75% of an emulsion copolymer of 60 parts of butyl acrylate and 40 parts of butadiene (iid = 1.512);

C ₂ graft copolymer of 40% styrene and acrylonitrile (75:25) to 60% of a partially crosslinked butyl polyacrylate (hd = 1.512);

C ₃ graft copolymer of 25% styrene and acrylonitrile (7f>: 30) to 75% of an emulsion polybutadiene (n _D = 1.532);

C ₄ graft copolymer of 37.5% styrene and acrylonitrile (75:25) to 62.5% of an emulsion polybutadiene («2> = 1.540).

The components were pre-mixed in a fluid mixer, and then intimately kneaded on a kneader at about 220 to 230 ⁰ C under nitrogen. The residence time was about 4 minutes. The granules obtained in this way were melted on a single-shaft extruder screw and chipped to form uniform granules suitable for injection molding processing. Table 1 shows the properties of the mixtures.

Comparative examples

In comparative tests, transparent mixtures were made according to the French regulations Patent 1 526 375 made from:

a) 45.6% A ₄ , 27.4% B and 27 ¹ V ₀ polybutadiene (n _D = 1.52),

b) 40% ₄ A, 24% B and 36% of polybutadiene (n _D = 1.52),

c) 27% ₄ A, 46% B and 27% of a copolymer of 71 parts of butadiene and 29 parts styrene {n _D = 1.541).

The results are shown in Table 2.

A comparison of these fracture energies with those from Table 1 shows that those produced according to the invention Products are much tougher than those made according to French Patent 1,526,375.

Table 1

at
game Together
settlement Fracture-
energy Limit bend
tension Vicat
number 1 54.6 A ₁
15.4 B
30.0 C ₁ 32 667 97 2 50.0 A ₂
14, OB
36.0 C ₁ 61 577 89 3 50.0 A ₃
14, OB
36.0 C ₁ 102 335 86 4th 43.2 A ₄
20.8 B
36.0 C ₁ 62 586 89.5 5 44.0 A ₂
14.0 b
42.0 C ₂ 70 681 95 6th 30.0 A ₄
34, OB
36.0 C ₃ 63 663 93 7th 21.3 A ₄
35.5 B
43.2 C ₄ 76 651 92.5

Table 2

example Fracture energy Limit bend
tension Vicat number a
b
C. <0.6
<0.6
<0.6 397
295
472 80
64
89.5

Claims (8)

ι 2 Refractive index of the rubber component) more flexible. Claim: if you have the individual, ready-polymerized components as if you were at the Transparent, impact-resistant molding compounds, best- polymerization the composition of the mono- starting from a mixture of 5 merengemisches must change. Another advantage ... ",. _o _ _. ,, _. . ,,,,. can be seen in the fact that the three mixture components A) 20 to 80 parts by weight of a Methylmeth- __ p _oIymethy i _me methacrylate, styrene-Acrylnitrilacrylat-PoIymensats prepared from 90 to IM weight _{PoIymerisat un} d -leichtzugängüche graft, percent methyl methacrylate and from 10 to OGe- ™ ^! Industrial scale products wight percent of a Alkyl acrylate with 1 to. , ⁶ ^ 8 carbon atoms in the alkyl group, ^{10 Sm} _N ä _chs tkommender prior art is the B) 10 to 50 parts by weight of a styrene / acrylic French patent 1 526 375. Thereafter, nitrile polymer from 70 to 90 weight percent transparent mixtures of polymethacrylate, cent styrene and 30 to 10 weight percent _styrene / acrylonitrile copolymers and rubbers are acrylonitrile , _{15 produced} by matching the refractive indices. C) 10 to 50 parts by weight of a graft copolymer. However, these three-part mixtures have no bcmerisats from 10 to 70 percent by weight of a satisfactory impact strength. Mixture of styrene and acrylonitrile in a _n I of the German Auslegeschrift 1169660 and m