WO2000020506A1

WO2000020506A1 - Housing for electrical devices containing small transformers

Info

Publication number: WO2000020506A1
Application number: PCT/EP1999/007434
Authority: WO
Inventors: Graham Edmund Mc Kee; Heiner GÖRRISSEN; Norbert Güntherberg; Norbert Niessner; Martin Weber
Original assignee: Basf Aktiengesellschaft
Priority date: 1998-10-07
Filing date: 1999-10-05
Publication date: 2000-04-13
Also published as: DE19846252A1

Abstract

The invention relates to the utilization of a shaped thermoplastic material different from ABS for the production of housings and the semi-finished products thereof for electrical devices containing small transformers, containing, in relation to the sum of the portions of components A, B and C and optionally D, a total of 100 % by weight of a: 1-48 % by weight of a single or multiphase particulate emulsion polymer with a glass transition temperature below O° C in at least one phase and a mean particle size of 50-1000 nm, preferably 50-800 nm as component A; b: 1-48 % by weight of at least one amorphous or semi-crystalline polymer as component B; c: 51-98 % by weight of a polycarbonate as component C and d: 0-47 % by weight of usual additives and/or fibrous or particulate filling materials or the mixtures thereof as component D.

Description

Housings of small transformers containing electrical devices

The invention relates to housings of small transformers containing electrical devices. In particular, the invention relates to such housings with good dimensional stability, great stability, good chemical resistance and good yellowing resistance.

To date, various materials have been used to manufacture housings for small transformers, such as for low-voltage power supplies for small electrical devices. Fire protection-equipped polyamide, for example, has only an extremely limited choice of colors due to the black-colored fire protection agent it contains. The housings also tend to shrink and warp. In a humid environment there is a high tendency to absorb water, which leads to dimensional changes. In addition, the housings are susceptible to yellowing.

Polypropylene housings tend to shrink and warp. In addition, the heat resistance is low.

ABS (acrylonitrile / butadiene / styrene) polymers show a tendency towards embrittlement and yellowing due to the cross-linking of the butadiene units. In addition, ABS is not always sufficiently resistant to cleaning agents and disinfectants.

The use of ASA (Acrylate / StyroVAcrynitril) withers with a low

Polycarbonate content leads to housings with not always sufficient scratch resistance and not always satisfactory swelling behavior. The color depth is too not always sufficient. Such housings are described in DE-A-196 30 120.

The object of the present invention is therefore to provide housings for small transformers-containing electrical devices which are stable and resistant to chemicals and do not yellow. They should also be scratch-resistant and have good dimensional stability. The UV and heat aging resistance should be high, so that the surface gloss is retained. Further requirements are good recyclability and poor fire behavior as well as good dimensional stability under thermal stress during manufacture and use.

According to the invention, these objects are achieved by using a thermoplastic molding composition different from ABS, comprising, based on the sum of the amounts of components A, B, C and optionally D, which gives a total of 100% by weight,

a: 1-48% by weight of at least one single-phase or multi-phase particulate emulsion polymer having a glass transition temperature below 0 ° C. in at least one phase and an average particle size of 50-1000 nm as component A,

b: 1-48% by weight of at least one amorphous or partially crystalline

Polymer as component B,

c: 51-98% by weight of polycarbonates as component C, and

d: 0-47% by weight of conventional additives and / or fibrous or particulate

Fillers or their mixtures as component D for the manufacture of housings and their semi-finished products from electrical transformers containing small transformers.

Specified glass transition temperatures of phases refer to a polymer with the composition corresponding to this phase.

The described housings of small transformers containing electrical devices are scratch-resistant, stable and resistant to chemicals. They also have very good yellowing resistance and depth of color.

The components of the thermoplastic molding compositions used for manufacturing the housings of small transformers containing electrical transformers according to the invention are known per se. For example, DE-A-12 60 135, DE-C-19 11 882, DE-A-28 26 925, DE-A-31 49 358, DE-A-32 27 555 and DE-A-40 11 162 Components and molding compositions which can be used according to the invention are described.

According to one embodiment the components A and B and C and optionally D, as defined below, contain the molding compounds used for the production of the housings of small transformers containing electrical transformers according to the invention. They contain, based on the sum of the amounts of components A, B, C and optionally D, which gives a total of 100% by weight,

a: 1-48% by weight, preferably 3-35% by weight, in particular 5-30% by weight, of a particulate emulsion polymer with a glass transition temperature below 0 ° C. and an average particle size of 50-1000 nm, preferably 50 - 800 nm, as component A, b: 1-48% by weight, preferably 5-40% by weight, in particular 5-35% by weight, of at least one amino or partially crystalline polymer as component B,

s c: 51-98% by weight, preferably 55-90% by weight, in particular 60-85% by weight, of polycarbonates as component C, and

d: 0 to 47% by weight, preferably 0 to 37% by weight, in particular 0 to 30% by weight of additives, and / or fibrous or particulate fillers or mixtures thereof as component D.

The invention is explained in more detail below.

The molding compositions used to manufacture the housings of 5 small transformers containing electrical devices according to the invention and the components from which they are constructed are first described.

COMPONENT A

Component A is at least one single-phase or multi-phase particulate emulsion polymer with a glass transition temperature below 0 ° C. in at least one phase and an average particle size of 50-1000 nm.

Component A is preferably a multi-phase polymer 5

al: 1-99% by weight, preferably 15-80% by weight, in particular 40-65% by weight

%, a particulate first phase AI with a glass transition temperature below 0 ° C, a2: 1-99% by weight, preferably 20-85% by weight, in particular 35-60

% By weight of a second phase A2 from the monomers, based on A2,

a21: 40-100% by weight, preferably 65-85% by weight, units of a vinylaromatic monomer, preferably styrene, a substituted styrene or a (meth) acrylic acid ester or mixtures thereof, in particular styrene and / or α-methylstyrene as component A21 and

a22: 0 to 60% by weight, preferably 15-35% by weight, of units of an ethylenically unsaturated monomer, preferably acrylonitrile or methacrylonitrile, in particular acrylonitrile as component A22.

a3: 0 to 50% by weight of a third phase with a glass transition temperature of more than 0 ° C. as component A3, the total amount of components AI, A2 and A3 giving 100% by weight.

The phases can be linked together in the manner of a graft copolymerization. Here, for example, the first phase AI can form the graft base and the second phase A2 a graft pad. Several phases can be provided, corresponding to a graft copolymer with one graft base and several graft pads. However, the graft pad need not necessarily be in the form of a sheath around the graft core. Different geometries are possible, for example part of the first phase AI can be covered with the second phase A2, interpenetrating networks can form etc. The first phase AI particularly preferably has a glass transition temperature below -10 ° C., in particular below - 15 ° C. The third phase preferably has a glass transition temperature greater than 60 ° C. This third phase can be present, for example, at 1-50% by weight, in particular 5-40% by weight, based on component A.

In the following, instead of "first phase" it can also be understood to mean "graft base", corresponding to "graft base" instead of "second phase".

The third phase can preferably be constructed from more than 50% by weight of styrene, in particular from more than 80% by weight of syrene, based on the total number of monomers of the third phase.

According to one embodiment of the invention, component AI consists of the monomers

all: 80 - 99.99 weight .-%, preferably 95 - 99.9 weight .-%, of a Cι _-8 - alkyl ester of acrylic acid, preferably n-butyl acrylate and / or

Ethyl hexyl acrylate as component All,

al2: 0.01-20% by weight, preferably 0.1-5.0% by weight, of at least one polyfunctional crosslinking monomer as component A12.

According to one embodiment of the invention, the average particle size of component A is 50-1000 nm, preferably 50-800 nm.

According to a further embodiment of the invention, the particle size distribution of component A is bimodal, with 1-99, preferably 20-95, in particular 45-90% by weight an average particle size of 50-200 nm and 1-99, preferably 5-80 , in particular 10-55% by weight have an average particle size of 200-1000 nm, based on the total weight of component A. The sizes determined from the integral mass distribution are given as the average particle size or particle size distribution. In all cases, the mean particle sizes according to the invention are the weight-average particle sizes, as determined by means of an analytical ultracentrifuge according to the method of W. Scholtan and H. Lange, Kolloid-Z. and Z.-Polymer 250 (1972), pages 782-796. The ultracentrifuge measurement provides the integral mass distribution of the particle diameter of a sample. From this it can be seen what percentage by weight of the particles have a diameter equal to or smaller than a certain size. The mean particle diameter, which is also referred to as the dso value of the integral mass distribution, is defined as the particle diameter at which 50% by weight of the particles have a smaller diameter than the diameter which corresponds to the dso value. Likewise, 50% by weight of the particles then have a larger diameter than the dso value. To characterize the width of the particle size distribution of the rubber particles, the dio and d ₉₀ values resulting from the integral mass distribution are used in addition to the dso value (average particle diameter). The dio or d ₉₀ value of the integral mass distribution is defined in accordance with the dso value with the difference that they are based on 10 or 90% by weight of the particles. The quotient

represents a measure of the distribution width of the particle size.

The glass transition temperature of the emulsion polymer A and also of the other components used according to the invention is determined by means of DSC (Differential Scanning Calorimetry) according to ASTM 3418 (mid point temperature). Relevant common rubbers can be used as emulsion polymer A, such as epichlorohydrin rubber, ethylene-vinyl acetate rubbers, polyethylene chlorosulfone rubbers, silicone rubbers, polyether rubbers, hydrogenated diene rubbers, according to one embodiment of the invention.

Polyalkename rubbers, acrylate rubbers, ethylene propylene rubbers, ethylene propylene diene rubbers, butyl rubbers and fluororubbers. Acrylate rubber, ethylene-propylene (EP) rubber, ethylene-propylene-diene (EPDM) rubber, in particular acrylate rubber, are preferably used.

Pure butadiene rubbers, such as those used in ABS, cannot be used as exclusive component A. The molding compositions are preferably free of butadiene rubbers.

According to one embodiment, the proportion of diene building blocks in the emulsion polymer A is kept so low that as few unreacted double bonds remain in the polymer as possible. According to one embodiment, there are no basic diene building blocks in the emulsion polymer A.

The acrylate is preferably alkyl acrylate rubbers of one or more Cι _-8 alkyl acrylates, preferably C4-8- alkyl acrylates, preferably wherein at least some butyl, hexyl, octyl or 2-ethylhexyl acrylate, in particular n-butyl and 2-ethylhexyl acrylate is used. These alkyl acrylate rubbers can contain up to 30% by weight of copolymerizable monomers, such as vinyl acetate, (meth) acrylonitrile, styrene, substituted styrene, methyl methacrylate or vinyl ether, in copolymerized form.

According to one embodiment of the invention, the acrylate rubbers furthermore contain 0.01-20% by weight, preferably 0.1-5% by weight, of crosslinking acting, polyfunctional monomers (crosslinking monomers). Examples of these are monomers which contain 2 or more double bonds capable of copolymerization, which are preferably not conjugated in the 1,3-positions.

Suitable crosslinking monomers are, for example, ethylene glycol di (meth) acrylate, butanediol or hexanediol di (meth) acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, diethyl phthalate, triallyl cyanurate, triallyl isocyanate phosphate, tricyclodecenyl acrylate, tricyclodecenyl acrylate, diaryl acrylate see DE-C-12 60 135).

Suitable silicone rubbers may, for example, crosslinked silicone rubbers of units of the general formulas R ₂ SiO, RSiO _3/2, R ₃ SiOι be / 2 and SiO 2/4, where the radical R is a monovalent radical. The amounts of the individual siloxane units are dimensioned so that 100 units of the formula R ₂ SiO 0 to 10 mole units of the formula RSiO _3/2, 0 to 1.5 moles of units R3SiOι / 2 and 0 to 3 moles of units SiÜ2 / 4 are available. R can be either a monovalent saturated hydrocarbon radical having 1 to 18 carbon atoms, the phenyl radical or the alkoxy radical or a group which is easily attackable by free radicals, such as the vinyl or mercaptopropyl radical. It is preferred that at least 80% of all R groups are methyl groups; combinations of methyl and ethyl or phenyl radicals are particularly preferred.

Preferred silicone rubbers contain built-in units of groups which can be attacked by free radicals, in particular vinyl, allyl, halogen, mercapto groups, preferably in amounts of 2-10 mol%, based on all radicals R. They can be prepared, for example, as in EP-A-0260 558. In some cases it may be appropriate to use an emulsion polymer A made from uncrosslinked polymer. All of the monomers mentioned above can be used as monomers for the production of these polymers. Preferred uncrosslinked emulsion polymers A are, for example, homopolymers and copolymers of acrylic esters, in particular n-butyl and ethylhexyl acrylate, and homopolymers and copolymers of ethylene, propylene, butylene, isobutylene and also poly (organosiloxanes), all with the proviso that they can be linear or branched.

Core / shell - emulsion polymer A

The emulsion polymer A can also be a multi-stage polymer (so-called "core / shell structure", "core-shell morphology"). For example, a rubber-elastic core (T _g <0 ° C) can be encased by a "hard" shell (polymers with T _g > 0 ° C) or vice versa.

In a particularly preferred embodiment of the invention, component A is a graft copolymer. The graft copolymers A of the molding compositions according to the invention have an average particle size dso of 50-1000 nm, preferably 50-800 nm.

The graft copolymer A is generally one or more stages, i.e. a polymer composed of a core and one or more shells. The polymer consists of a basic stage (graft core) AI and a plurality of stages grafted onto it A2 (graft pad), the so-called graft stages or graft shells.

One or more graft shells can be applied to the rubber particles by simple grafting or multiple stepwise grafting, each Graft shell can have a different composition. In addition to the grafting monomers, polyfunctional crosslinking or reactive group-containing monomers can also be grafted on (see, for example, EP-A-0 230 282, DE-A-36 01 419, EP-A-0 269 861).

In a preferred embodiment, component A consists of a multi-stage graft copolymer, the graft stages being generally made from resin-forming monomers and having a glass transition temperature T _g above 30 ° C., preferably above 50 ° C. The outer graft shell serves, among other things, to achieve (partial) compatibility of the rubber particles A with the thermoplastic B.

Graft copolymers A are prepared, for example, by grafting at least one of the monomers A2 listed below onto at least one of the graft bases or graft core materials AI listed above. All polymers described above under emulsion polymers A are suitable as graft bases AI of the molding compositions according to the invention.

According to one embodiment of the invention, the graft base AI is composed of 15-99.9% by weight of acrylate rubber, 0.1-5% by weight of crosslinking agent and 0-49.9% by weight of one of the further monomers or rubbers indicated.

Suitable monomers for forming the graft A2 can be selected, for example, from the monomers listed below and their mixtures:

Vinylaromatic monomers, such as styrene and its substituted derivatives, such as ct-methylstyrene, p-methylstyrene, 3,4-dimethylstyrene, p-tert-butylstyrene, and p-methyl-α-methylstyrene or C 1 -C ₈ -alkyl (meth) acrylates such as methyl methacrylate, Ethyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate; preferred are styrene, α-methyl _s Tyrol, methyl methacrylate, particularly styrene and / or α-methyl styrene, and ethylenically unsaturated monomers such as acrylic and methacrylic compounds such as acrylonitrile, methacrylonitrile, acrylic and methacrylic acid, methyl acrylate, ethyl acrylate, n- and isopropyl acrylate , n- and isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n- and isopropyl methacrylate, n- and isobutyl methacrylate, tert-buryl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate,

Maleic anhydride and its derivatives such as maleic esters, maleic diesters and maleimides, e.g. Alkyl and aryl maleimides, such as methyl, cyclohexyl or phenyl maleimide. Methacrylates, acrylonitrile and methacrylonitrile, in particular acrylonitrile, are preferred.

Furthermore, as (co) monomers styrene, vinyl, acrylic or methacrylic compounds (for example styrene, optionally substituted with C 12 alkyl radicals, halogen atoms, halogen methylene radicals; vinyl naphthalene, Nmylcarbazole; vinyl ethers with Ci 12 ether radicals; vinyl imidazole , 3- (4-) vinylpyridine, dimethylaminoethyl (meth) acrylate, p-dimethylaminostyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, butyl acrylate, ethylhexyl acrylate and methyl methacrylate as well as fumaric acid, maleic acid, itaconic acid or their anhydrides, amides, or nitriles 1 to 22 carbon atoms, preferably alcohols containing 1 to 10 carbon atoms) can be used.

According to one embodiment of the invention, component A comprises 50 to 100% by weight, preferably 50 to 90% by weight of the first phase described above (graft base) Al and 0 to 50% by weight, preferably 10 to 50% by weight the above-described second phase (graft) A2, based on the total weight of component A. In particular, styrene copolymers can be considered as the third phase. According to one embodiment of the invention, crosslinked acrylic acid ester polymers with a glass transition temperature below 0 ° C. serve as the graft base. The crosslinked acrylic ester polymers should preferably have a glass transition temperature below -20 ° C., in particular below -30 ° C.

In a preferred embodiment, the graft A2 consists of one or more graft shells, the outermost graft shell of which has a glass transition temperature of more than 30 ° C., wherein a polymer formed from the monomers of the graft A2 would have a glass transition temperature of more than 80 ° C.

With regard to the measurement of the glass transition temperature and the average particle size and the Q values, what has been said for the emulsion polymers A applies to the graft copolymers A.

The graft copolymers A can also be prepared by grafting pre-formed polymers onto suitable graft homopolymers. Examples of this are the reaction products of copolymers containing maleic anhydride or acid groups with base-containing rubbers.

Suitable preparation processes for graft copolymers A are emulsion, solution, bulk or suspension polymerization. The graft copolymers A are preferably prepared by free-radical emulsion polymerization, in particular in the presence of latices of component AI at temperatures from 20 ° C. to 90 ° C. using water-soluble or oil-soluble initiators such as peroxodisulfate or benzoyl peroxide, or with the aid of redox initiators. Redox initiators are also suitable for polymerization below 20 ° C. Suitable emulsion polymerization processes are described in DE-A-28 26 925, 31 49 358 and in DE-C-12 60 135.

The graft casings are preferably built up in the emulsion polymerization process as described in DE-A-32 27 555, 31 49 357, 31 49 358, 34 14 118. The defined particle sizes of 50-1000 nm according to the invention are preferably carried out after the processes that are described in DE-C-12 60 135 and DE-A-28 26 925, or Applied Polymer Science, Volume 9 (1965), page 2929. The use of polymers with different particle sizes is known, for example, from DE -A-28 26 925 and US 5,196,480 known.

According to the process described in DE-C-12 60 135, the graft base AI is first prepared by adding the acrylic acid ester or esters used according to one embodiment of the invention and the multifunctional crosslinking monomers, optionally together with the other comonomers, in aqueous Emulsion in a conventional manner at temperatures between 20 and 100 ° C, preferably between 50 and 80 ° C, polymerized. The usual emulsifiers, such as alkali salts of alkyl or alkylarylsulfonic acids, alkyl sulfates, fatty alcohol sulfonates, salts of higher fatty acids with 10 to 30 carbon atoms or resin soaps can be used. The sodium salts of alkyl sulfonates or fatty acids having 10 to 18 carbon atoms are preferably used. According to one embodiment, the emulsifiers are used in amounts of 0.5-5% by weight, in particular 1-2% by weight, based on the monomers used in the preparation of the graft base AI. In general, the weight ratio of water to monomers is from 2: 1 to 0.7: 1. The usual persulfates, such as potassium persulfate, in particular, serve as polymerization initiators. However, redox systems can also be used. The initiators are generally used in amounts of 0.1-1% by weight, based on the production of the Graft base AI monomers used. Further polymerization auxiliaries which can be used are the customary buffer substances, by means of which pH values of preferably 6-9, such as sodium bicarbonate and sodium pyrophosphate, and 0-3% by weight of a molecular weight regulator, such as mercaptans, terpinols or dimeric α-methylstyrene, during the polymerization be used.

To produce the graft polymer A, a monomer mixture of styrene and acrylonitrile is then polymerized in a next step in the presence of the latex of the crosslinked acrylic ester polymer thus obtained, the weight ratio of styrene to acrylonitrile in the monomer mixture according to one embodiment of the invention in the range from 100: 0 to 40:60, preferably in the range from 65: 35 to 85: 15. It is advantageous to carry out this graft copolymerization of styrene and acrylonitrile on the crosslinked polyacrylic ester polymer used as the graft base again in an aqueous emulsion under the customary conditions described above. The graft copolymerization can expediently take place in the same system as the emulsion polymerization for the preparation of the graft base AI, it being possible, if necessary, to add further emulsifier and initiator. The monomer mixture of styrene and acrylonitrile to be grafted on according to one embodiment of the invention can be added to the reaction mixture all at once, batchwise in several stages or preferably continuously during the polymerization. The graft copolymerization of the mixture of styrene and acrylonitrile in the presence of the crosslinking acrylic ester polymer is carried out in such a way that a degree of grafting of 1-99% by weight, preferably 20-85% by weight, in particular 35-60% by weight, based on the Total weight of component A, resulting in graft copolymer A. Since the graft yield in the graft copolymerization is not 100%, a somewhat larger amount of the monomer mixture of styrene and acrylonitrile must be used in the Graft copolymerization can be used as it corresponds to the desired degree of grafting. The control of the graft yield during the graft copolymerization and thus of the degree of grafting of the finished graft copolymer A is known to the person skilled in the art and can be carried out, for example, by the metering rate of the monomers or by adding a regulator (Chauvel, Daniel, ACS Polymer Preprints 15 (1974), page 329 ff ). The emulsion graft copolymerization generally gives rise to a few% by weight, based on the graft copolymer, of free, ungrafted styrene / acrylonitrile copolymer. The proportion of the graft copolymer A in the polymerization product obtained in the graft copolymerization is determined by the method given above.

In the production of the graft copolymers A by the emulsion process, in addition to the given process engineering advantages, reproducible particle size changes are also possible, for example by at least partially agglomeration of the particles into larger particles. This means that polymers with different particle sizes can also be present in the graft copolymers A.

In a particular embodiment, bimodal particle size distributions of component A have proven to be particularly advantageous. These can be generated by mixing separately produced particles of different sizes, which can also differ in their composition and shell structure (core / shell, core / shell / shell, etc.), or a bimodal particle size distribution can be generated by partial agglomeration , during or after the grafting.

Component A, in particular, consisting of the graft base and graft shell (s) can be optimally adapted for the particular intended use, in particular with respect to the particle size.

The graft copolymers A generally contain 1-99% by weight, preferably 15-80 and particularly preferably 40-65% by weight of the first phase (graft base) Al and 1-99% by weight, preferably 20-85, particularly preferably 35-60% by weight of the second phase (graft) A2, based in each case on the entire graft copolymer.

COMPONENT B

Component B is an amorphous or partially crystalline polymer.

Component B is preferably a copolymer of

bl: 40-100% by weight, preferably 60-85% by weight, of units of a vinylaromatic monomer, preferably styrene, a substituted styrene or a (meth) acrylic acid ester or mixtures thereof, in particular styrene and / or α Methylstyrene as component B1,

b2: 0 to 60% by weight, preferably 15-40% by weight, units of an ethylenically unsaturated monomer, preferably acrylonitrile or methacrylonitrile, in particular acrylonitrile as component B2,

b3: 0 to 60% by weight of a further ethylenically unsaturated copolymerizable monomer.

According to a preferred embodiment of the invention, the viscosity number of component B is 50-120, preferably 55-100.

The amorphous or partially crystalline polymers of component B for Manufacture of the housing according to the invention of electrical equipment containing small transformers used according to the invention are made of at least one polymer from partially crystalline polyamides, partially aromatic copolyamides, polyolefins, ionomers, polyesters, polyether ketones, polyoxyalkylenes, polyarylene sulfides and preferably polymers from vinyl aromatic monomers and / or ethylenically unsaturated Monomers selected. Polymer mixtures can also be used.

As component B of the electrical devices used for producing the housings of small transformers according to the invention

Molding compositions are also partially crystalline, preferably linear polyamides such as polyamide-6,

Polyamide-6,6, polyamide-4,6, polyamide-6,12 and partially crystalline copolyamides

Suitable based on these components. Furthermore, partially crystalline polyamides can be used, the acid components of which are wholly or partly composed of adipic acid and / or terephthalic acid and / or isophthalic acid and / or suberic acid and / or

Sebacic acid and / or acelaic acid and / or dodecanedicarboxylic acid and / or one

Cyclohexanedicarboxylic acid consists, and the diamine component wholly or partly consists in particular of m- and / or p-xylylenediamine and / or hexamethylene diamine and / or 2,2,4- and / or 2,4,4-trimethymexamethylene diamine and / or isophorone diamine, and whose compositions are known in principle from the prior art (cf. Encyclopedia of Polymers, Vol. 11, p. 315 ff.).

Examples of polymers which are furthermore suitable as component B of the molding compositions used according to the invention for producing the housings of electrical transformers containing electrical transformers are partially crystalline polyolefins, preferably homo- and copolymers of olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene and heptene -1, 3-methylbutene-1, 4-methylbutene-1, 4-methylpentene-1 and octene-1. Suitable polyolefins are polyethylene, Polypropylene, polybutene-1 or poly-4-methylpentene-l. In general, a distinction is made between polyethylene (PE) and high-density PE (HDPE), low-density PE (LDPE) and linear-low-density PE (LLDPE).

In another embodiment of the invention, component B is an ionomer. These are generally polyolefins as described above, especially polyethylene, which contain monomers co-condensed with acid groups, e.g. Acrylic acid, methacrylic acid and possibly other copolymerizable monomers. The acid groups are generally converted into ionic, possibly ionically crosslinked polyolefins with the aid of metal ions such as Na, Ca, Mg and Al, but these can still be processed thermoplastically (see, for example, US 3,264,272; 3,404,134; 3,355,319; 4,321,337). However, it is not absolutely necessary to convert the polyolefins containing acid groups by means of metal ions. Also polyolefins containing free acid groups, which then generally have a rubber-like character and in some cases also contain further copolymerizable monomers, e.g. (Meth) acrylates are suitable as component B according to the invention.

In addition, component B can also be polyester, preferably aromatic-aliphatic polyester. Examples are polyalkylene terephthalates, e.g. based on ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and 1,4-bis-hydroxymethyl-cyclohexane, as well as polyalkylene naphthalates.

Aromatic polyether ketones can also be used as component B, as described, for example, in GB 1 078 234, US Pat. No. 4,010,147, EP-A-0 135 938, EP-A-0 292 211, EP-A-0 275 035, EP-A-0 270 998, EP-A-0 165 406, and in the publication by CK Sham et. al., Polymer 29/6, 1016-1020 (1988). Furthermore, component B of the molding compositions used according to the invention for the production of the housings of small transformers containing electrical devices can be used polyoxyalkylenes, for example polyoxymethylene, and oxymethylene polymers.

Other suitable components B are the polyarylene sulfides, in particular the polyphenylene sulfide.

An amorphous copolymer of styrene and αV- or α-methylstyrene with acrylonitrile is preferably used as component B. The acrylonitrile content in these

Copolymers of component B are 0-60% by weight, preferably 15

- 40 wt .-%, based on the total weight of component B. To the component

B also includes those in the graft copolymerization to produce the component

A free, non-grafted styrene / acrylonitrile copolymers formed. Depending on the conditions chosen for the production of the graft copolymer A in the graft copolymerization, it may be possible that a sufficient proportion of component B has already been formed in the graft copolymerization. In general, however, it will be necessary to mix the products obtained in the graft copolymerization with additional, separately prepared component B.

This additional, separately prepared component B can preferably be a styrene / acrylonitrile copolymer, an α-methylstyrene / acrylonitrile copolymer or an α-methylstyrene / styrene-acrylonitrile terpolymer. These copolymers can be used individually or as a mixture for component B, so that the additional, separately prepared component B of the molding compositions used according to the invention is, for example, a mixture of a styrene / acrymitrile copolymer and an α-methylstyrene / acrylonitrile Copolymer can act. In the case where component B of the molding compositions used according to the invention consists of a mixture of a styrene / acrylonitrile copolymer and an α-methylstyrene acrylonitrile copolymer, the acrylonitrile content of the two copolymers should preferably be no more than 10% by weight, preferably no more than 5% by weight .-%, based on the total weight of the copolymer, differ from each other. Component B of the molding compositions used according to the invention can, however, also consist of only a single styrene / acrylonitrile copolymer if, in the graft copolymerizations for the preparation of component A and also in the preparation of the additional, separately prepared component B, the same monomer mixture of styrene and Acrylonitrile is assumed.

The additional, separately manufactured component B can be obtained by the conventional methods. Thus, according to one embodiment of the invention, the copolymerization of the styrene and / or α-methylstyrene with the acrylonitrile can be carried out in bulk, solution, suspension or aqueous emulsion. Component B preferably has a viscosity number of 40 to 120, preferably 50 to 120, in particular 55 to 100. The viscosity number is determined in accordance with DIN 53 726, 0.5 g of material being dissolved in 100 ml of dimethylformamide.

Components A and B can be mixed in any conventional manner using all known methods. If components A and B have been prepared, for example, by emulsion polymerization, it is possible to mix the polymer dispersions obtained with one another, to precipitate the polymers together thereupon and to work up the polymer mixture. However, components A and B are preferably mixed by extruding, kneading or rolling the components together, the components having, if necessary, been isolated beforehand from the solution or aqueous dispersion obtained in the polymerization. The in aqueous dispersion The graft copolymerization products obtained (component A) can also only be partially dewatered and mixed with component B as a moist crumb, the complete drying of the graft copolymers then taking place during the mixing.

5

COMPONENT C

Suitable polycarbonates C are known per se. They preferably have a molecular weight (weight average M _w , determined by means of gel permeation chromatography in tetrahydrofuran against polystyrene standards) in the range from 10,000 to 60,000 g / mol. They can be obtained, for example, in accordance with the processes of DE-B-1 300 266 by interfacial polycondensation or in accordance with the process of DE-A-1 495 730 by reacting diphenyl carbonate with bisphenols. Preferred bisphenol is 2,2-di (4-hydroxyphenyl) propane, generally - as also hereinafter - referred to as bisphenol A.

15

Instead of bisphenol A, other aromatic dihydroxy compounds can also be used, in particular 2,2-di (4-hydroxyphenyl) pentane, 2,6-dihydroxynaphthalene, 4,4'-dihydroxydiphenylsulfane, 4,4 ^, -dihydroxydiphenyl ether, 4,4'- Dihydroxydiphenyl sulfite, 4,4'-dihydroxydiphenylmethane, 1, 1-di- (4-

20 hydroxyphenyl) ethane, 4,4-dihydroxydiphenyl or dihydroxydiphenylcycloalkanes, preferably dihydroxydiphenylcyclohexanes or dihydroxylcyclopentanes, in particular 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and mixtures of the aforementioned dihydroxy compounds.

25 Particularly preferred polycarbonates are those based on bisphenol A or bisphenol A together with up to 80 mol% of the aromatic dihydroxy compounds mentioned above.

Copolycarbonates according to US Pat. No. 3,737,409 can also be used; of Of particular interest are copolycarbonates based on bisphenol A and di (3,5-dimethyl-dihydroxyphenyl) sulfone, which are characterized by high heat resistance. It is also possible to use mixtures of different polycarbonates.

According to the invention, the average molecular weights (weight average M _w , determined by means of gel permeation chromatography in tetrahydrofuran against polystyrene standards) of the polycarbonates C are in the range from 10,000 to 64,000 g / mol. They are preferably in the range from 15,000 to 63,000, in particular in the range from 15,000 to 60,000 g / mol. This means that the polycarbonates C have relative solution viscosities in the range from 1.1 to 1.3, measured in 0.5% strength by weight solution in dichloromethane at 25 ° C., preferably from 1.15 to 1.33. The relative solution viscosities of the polycarbonates used preferably differ by no more than 0.05, in particular no more than 0.04.

The polycarbonates C can be used both as regrind and in granular form. They are present as component C in amounts of 51-98% by weight, preferably 55-90% by weight, in particular 60-85% by weight, based in each case on the total molding composition.

According to one embodiment of the invention, the addition of polycarbonates leads, inter alia, to higher thermal stability and improved crack resistance of the molding compositions used according to the invention for producing the housings of electrical transformers containing small transformers.

COMPONENT D

As component D, the electrical devices used for producing the housings according to the invention of small transformers contain according to the invention preferred thermoplastic molding compositions 0-50% by weight, preferably 0-37% by weight, in particular 0-30% by weight fibrous or particulate fillers and other additives or mixtures thereof, in each case based on the total molding composition. These are preferably commercially available products.

Reinforcing agents such as carbon fibers and glass fibers are usually used in amounts of 5-50% by weight, based on the total molding composition.

The glass fibers used can be made of E, A or C glass and are preferably equipped with a size and an adhesion promoter. Their diameter is generally between 6 and 20 μm. Both continuous fibers (rovings) and chopped glass fibers (staple) can be used.

Furthermore, fillers or reinforcing materials such as glass balls, mineral fibers, whiskers, aluminum oxide fibers, mica, quartz powder and wollastonite can be added.

In addition, metal flakes (e.g. aluminum flakes from Transmet Corp.), metal powder, metal fibers, metal coated fillers, e.g. nickel-coated glass fibers and other additives that shield electromagnetic waves are mixed into the molding compositions used according to the invention for producing the housing according to the invention. Aluminum flakes (K 102 from Transmet) are particularly suitable for EMI (electro-magnetic interference) purposes. Furthermore, the compositions can be mixed with additional carbon fibers, carbon black, in particular conductivity carbon black, or nickel-coated carbon fibers.

The molding compositions used according to the invention for the production of the housings of small transformers containing electrical devices according to the invention can furthermore contain further additives D which are typical and customary for polycarbonates, SAN polymers and graft copolymers or mixtures thereof. Examples of such additives are: dyes, pigments, colorants, antistatic agents, antioxidants, stabilizers for improving the thermostability, for increasing the light stability, for increasing the hydrolysis resistance and the chemical resistance, buffer substances, flame retardants, drip inhibitors, transesterification inhibitors, agents against heat decomposition and especially against heat decomposition Lubricants / lubricants and waxes which are useful for the production of moldings or moldings. These additional additives can be metered in at any stage of the production process, but preferably at an early point in time, in order to take advantage of the stabilizing effects (or other special effects) of the additive at an early stage. Heat stabilizers or oxidation retardants are usually metal halides (chlorides, bromides, iodides) which are derived from metals of group I of the periodic table of the elements (such as Li, Na, K, Cu). Other suitable stabilizers are the usual hindered phenols, but also vitamin E or compounds of an analog structure. Also HALS stabilizers (hindered amine light stabilizers), benzophenones, resorcinols, salicylates,

SD

Benzorriazoles and other compounds are suitable (for example Irganox, Tinuvin ^® , such as Tinuvin ^® 770 (HALS absorber, bis (2,2,6,6-tetramethyl-4-piperidyl) sebazate) or Tinuvin ^® P (UV absorber - ( 2H-benzotriazol-2-yl) -4-methylphenol), topanol). These are usually used in amounts of up to 2% by weight (based on the total mixture).

Suitable lubricants and mold release agents are stearic acids, stearyl alcohol, stearic acid esters or generally higher fatty acids, their derivatives and corresponding fatty acid mixtures with 12-30 carbon atoms. The amounts of these additives are in the range of 0.05-1% by weight. Silicone oils, oligomeric isobutylene or similar substances are also suitable as additives, the usual amounts being 0.05-5% by weight. Pigments, dyes, color brighteners such as ultramarine blue, phthalocyanines, titanium dioxide, cadmium sulfides, derivatives of perylene tetracarboxylic acid can also be used.

Commercial halogen-free or halogen-containing flame retardants can also be used in customary amounts, for example up to 50% by weight. Examples of halogen-free flame retardants are described in EP-A-0 149 813. Otherwise, reference is made to DE-A-34 36 815, poly (tetrabromobisphenol A (glycidyl) ether) having a molecular weight of 40,000 being particularly preferred.

Processing aids and stabilizers such as UV stabilizers, lubricants and antistatic agents are usually used in amounts of 0.01-5% by weight, based on the total molding composition.

The thermoplastic molding compositions used according to the invention for manufacturing the housings of small transformers containing electrical transformers according to the invention can be produced by methods known per se by mixing the components. It can be advantageous to premix individual components. Mixing the components in solution and removing the solvents is also possible.

Suitable organic solvents are, for example, chlorobenzene, mixtures of chlorobenzene and methylene chloride or mixtures of chlorobenzene or aromatic hydrocarbons, e.g. Toluene.

The solvent mixtures can be evaporated, for example, in evaporation extruders. The dry components, for example, can be mixed by all known methods. However, the mixing is preferably carried out by extruding, kneading or rolling the components together, preferably at temperatures of 180-400 ° C., the components having, if necessary, been isolated beforehand from the solution obtained in the polymerization or from the aqueous dispersion.

The components can be metered in together or separately in succession.

According to one embodiment of the invention, the housings of electrical devices containing small transformers according to the invention can be produced from the thermoplastic molding compositions used according to the known methods of thermoplastic processing. In particular, the production can be carried out by thermoforming, extrusion, injection molding, calendering, blow molding, pressing, press sintering, deep drawing or sintering, preferably by injection molding. Especially in calendering and deep drawing, plates and foils are produced or used as an intermediate stage.

The molding compositions used according to the invention are used for the production of housings and their semi-finished products for electrical devices containing small transformers.

Such electrical devices can, for example, be devices in which other electrical assemblies or mechanical assemblies are accommodated in addition to small transformers. Examples are computers and consumer electronics from the audio or video sector. The housings can also be used, for example, for power supplies or battery chargers. The housing can also only be the transformer and other small electronic components such as diodes or pick up rectifier. Such separate transformers are often used for low-voltage power supply. They are used, for example, for lighting (halogen spotlights). Power supplies that are used separately from electrical devices and consist of a plug-in transformer that is plugged directly into a conventional socket and a connecting cable for the electrical device are widespread. The housings according to the invention can be used in particular where they are exposed to heat and light. Due to the heat development in transformers, these are usually exposed to permanent stress.

The housings can have any shape, provided that this allows the inclusion of small transformers. Usually, the housings, in particular on power supplies or chargers for accumulators, have only small gaps between the wall and the small transformer, so that they are in close thermal contact with the small transformer.

The housings consisting of the molding compositions according to the invention have very good chemical resistance and dimensional stability. In addition, they are scratch-resistant, which is particularly advantageous when cleaning.

In addition, the housings of electrical transformers containing small transformers according to the invention are resistant to yellowing and very stable. They have a balanced ratio of toughness and bending stiffness.

Due to the high content of polycarbonates in the molding compounds, the housings of electrical transformers containing small transformers are very heat-resistant and resistant to lasting heat. By adding the polycarbonate as component C, the heat resistance and impact resistance of the housings of electrical transformers containing small transformers are further improved. These housings for small transformers-containing electrical devices also have good dimensional stability and excellent resistance to heat aging and high resistance to yellowing under thermal stress and exposure to UV radiation.

The housings of small transformers containing electrical devices have excellent surface properties, which can be obtained without further surface treatment. The appearance of the finished surfaces of the housings of electrical devices containing gill transformers can be modified by suitable modification of the rubber morphology, for example in order to achieve glossy or matt surface designs. The housings of small transformers containing electrical devices show a very low graying or yellowing effect when exposed to weather and UV radiation, so that the surface properties are retained. Further advantageous properties of the housings of electrical transformers containing small transformers are the high weather stability, good thermal resistance, high yellowing resistance under UV radiation and thermal stress, good stress crack resistance, in particular when exposed to chemicals, and good anti-electrostatic behavior. In addition, they have high color stability, for example due to their excellent resistance to yellowing and embrittlement. The housings of small transformers-containing electrical devices according to the invention made of the thermoplastic molding compositions used according to the invention show no significant loss of toughness or impact strength at low temperatures or after prolonged exposure to heat, which loss is retained even when exposed to UV rays. The tensile strength is also retained. Furthermore, the molding compositions or housings of electrical transformers containing small transformers according to the invention show high resistance to scratching, high resistance to swelling and low permeability to liquids and gases, such as also good fire resistance.

It is possible to recycle the thermoplastic molding compositions already used to produce the housings of electrical transformers containing small transformers according to the present invention. Because of the high color stability, weather resistance and aging resistance, the molding compositions used according to the invention are very suitable for reuse. The proportion of reused (recycled) molding compound can be high. When using, for example, 30% by weight of molding compound already used, which was mixed in the ground form with the molding compounds used according to the invention, the relevant material properties changed, such as flowability, Vicat softening temperature and impact resistance of the molding compounds and the housing of small transformers containing them produced according to the invention Electrical appliances not significant. Similar results were obtained when the weather resistance was examined. The impact strength was constant for a long time even when using recycled thermoplastic molding compositions, see Lindenschmidt, Ruppmich, Hoven-Nievelstein, International Body Engineering Conference, September 21-23, 1993, Detroit, Michigan, USA, Interior and Exterior Systems, pages 61 to 64. The resistance to yellowing was also retained.

The invention is illustrated by the following examples.

EXAMPLES

example 1

Production of small-part graft copolymer (A)

(al) 16 parts of butyl acrylate and 0.4 part of tricyclodecenyl acrylate were in 150 parts of water with the addition of part of the sodium salt of a C12 to C ₈ paraffmsulfonic acid, 0.3 part of potassium per-sulfate, 0.3 part of sodium hydrogen carbonate and 0.15 Divide sodium pyrophosphate under

Stirring heated to 60 ° C. A mixture of 82 parts of butyl acrylate and 1.6 parts of tricyclodecenyl acrylate was added within 3 hours 10 minutes after the start of the polymerization reaction. After the monomer addition had ended, the mixture was left to react for an hour. The latex of the crosslinked butyl acrylate polymer obtained had a solids content of 40% by weight. The mean particle size (weight average) was found to be 76 nm. The particle size distribution was narrow (quotient Q = 0.29).

(a2) 150 parts of the polybutyl acrylate latex obtained according to (a1) were mixed with 40 parts of a mixture of styrene and acrylonitrile (weight ratio 75:25) and 60 parts of water and with stirring after the addition of a further 0.03 part of potassium persulfate and 0. 05 parts of lauroyl peroxide heated to 65 ° C for 4 hours. After the end of the graft copolymerization, the polymerization product was precipitated from the dispersion using calcium chloride solution at 95 ° C., washed with water and dried in a warm air stream. The degree of grafting of the graft polymer was 35%. Example 2

Production of large-scale graft copolymer (A)

(al) On the one hand, after adding 50 parts of water and 0.1 part of potassium persulfate, a mixture of 49 parts of butyl acrylate and 1 Part of tricyclodecenyl acrylate and on the other hand a solution of 0.5 part of the sodium salt of a C12 to cis paraffin sulfonic acid in 25 parts

Let water run in at 60 ° C. After the end of the feed, polymerization was continued for 2 hours. The latex of the crosslinked butyl acrylate polymer obtained had a solids content of 40%. The average particle size (weight average of the latex) was found to be 288 nm. The particle size distribution was narrow (Q = 0.1).

(a2) 150 parts of this latex were mixed with 40 parts of a mixture of styrene and acrylonitrile (ratio 75:25) and 110 parts of water and with stirring after the addition of a further 0.03 part of potassium persulfate and 0.05 part of lauroyl peroxide to 65 for 4 hours ° C heated. That at the

The polymerization product obtained from the graft copolymerization was then precipitated from the dispersion using a calcium chloride solution at 95 ° C., separated off, washed with water and dried in a warm air stream. The degree of grafting of the graft polymer was determined to be 27%.

Example 3

Production of large-scale graft copolymer (A) (al) 16 parts of butyl acrylate and 0.4 part of tricyclodecenyl acrylate were in 150 parts of water with the addition of 0.5 part of the sodium salt of a C12 to C ₈ paraffin sulfonic acid, 0.3 part of potassium persulfate, 0.3 part of sodium hydrogen carbonate and 0.15 Parts of sodium pyrophosphate heated to 60 ° C with stirring. 10 minutes after the start of the

A reaction mixture of 82 parts of butyl acrylate and 1.6 parts of tricyclodecenyl acrylate was added over the course of 3 hours. After the monomer addition had ended, the mixture was left to react for an hour. The latex of the crosslinked butyl acrylate polymer obtained had a solids content of 40% by weight. The average particle size

(Weight average) was determined to be 216 nm. The particle size distribution was narrow (Q = 0.29).

(a2) 150 parts of the polybutyl acrylate latex obtained according to (a1) were mixed with 20 parts of styrene and 60 parts of water and with stirring after the addition of a further 0.03 part of potassium persulfate and 0.05 part of lauroyl peroxide 3

Heated to 65 ° C for hours. After completing the first stage of

The graft polymer had a graft copolymerization

Degree of grafting of 17%. This graft copolymer dispersion was, without further additives, with 20 parts of a mixture of styrene and acrylonitrile

(75: 25 ratio) polymerized for a further 3 hours. After completing the

The product was precipitated from the dispersion using calcium chloride solution at 95 ° C., washed with water and in the warm

Airflow dried. The degree of grafting of the graft copolymer was 35%, the average particle size of the latex particles was found to be 238 nm.

Example 4

Production of large-scale graft copolymer (A) (al) On the one hand, a mixture of 49 parts of butyl acrylate and 1 part of tricyclodecenyl acrylate were added to a template from 2.5 parts of the latex produced in Example 3 (component A) after the addition of 50 parts of water and 0.1 part of potassium persulfate over the course of 3 hours and on the other hand, a solution of 0.5 parts of the sodium salt of a C12- to cis-paraffin sulfonic acid in 25 parts of water was run in at 60.degree. After the end of the feed, polymerization was continued for 2 hours. The latex of the crosslinked butyl acrylate polymer obtained had a solids content of 40%. The mean particle size (weight average) of the latex was found to be 410 nm. The particle size distribution was narrow (Q = 0.1).

Heated to 65 ° C for hours. The dispersion obtained in this graft copolymerization was then polymerized with 20 parts of a mixture of styrene and acrylonitrile in a ratio of 75:25 for a further 4 hours. The reaction product was then precipitated from the dispersion using a calcium chloride solution at 95 ° C., separated off, washed with water and dried in a warm air stream. The degree of grafting of the graft copolymer was determined to be 35%, and the average particle size of the latex particles was 490 nm.

Example 5

Production of large-scale graft copolymer (A)

(al) 98 parts of butyl acrylate and 2 parts of tricyclodecenyl acrylate were mixed in 154 Polymerized parts of water with the addition of 2 parts of dioctylsulfosuccinate sodium (70%) as emulsifier and 0.5 parts of potassium persulfate for 3 hours at 65 ° C. An approximately 40% dispersion was obtained. The average particle size of the latex was approximately 100 nm.

5

A mixture of 49 parts of butyl acrylate, 1 part of tricyclodecenyl acrylate and 0.38 part of the emulsifier was added at 65 ° C. to an initial charge of 2.5 parts of this latex, 400 parts of water and 0.5 part of potassium persulfate within 1 hour. In the course of another

A mixture of 49 parts of butyl acrylate, 1

Part of tricyclodecenyl acrylate and 0.76 part of emulsifier. After adding 1 part of potassium persulfate in 40 parts of water, a mixture of 196 parts of butyl acrylate, 4 parts of tricyclodecenyl acrylate and 1.52 parts of the emulsifier was finally added within 2 hours

15 added dropwise. The polymer mixture was then polymerized at 65 ° C. for a further 2 hours. An approximately 40% dispersion with an average particle diameter of approximately 500 nm was obtained.

If only 100 parts were added instead of a total of 300 parts of monomers, 20 was obtained from a latex with an average particle diameter of about 300 nm.

(a2) 465 parts of styrene and 200 parts of acrylonitrile were in the presence of 2500 parts of the polymer latex according to (al) with the mean particle size 0.1 and

25 0.3 or 0.5 μm, 2 parts potassium sulfate, 1.33 parts lauryl peroxide and 1005

Parts of water polymerized with stirring at 60 ° C. A 40% dispersion was obtained, from which the solid product was precipitated by adding a 0.5% calcium chloride solution, washed with water and dried. Example 6

Production of copolymer (B)

A monomer mixture of styrene and acrylonitrile was polymerized in solution under normal conditions. The styrene / acrylonitrile copolymer obtained had an acrylonitrile content of 35% by weight, based on the copolymer, and a viscosity number of 80 ml g.

Example 7

Production of copolymer (B)

A monomer mixture of styrene and acrylonitrile was polymerized in solution under normal conditions. The styrene-acrylonitrile copolymer obtained had an acrylonitrile content of 35% by weight, based on the copolymer, and a viscosity number of 60 ml / g.

Example 8

Production of copolymer (B)

A monomer mixture of styrene and acrylonitrile was polymerized in solution under customary conditions. The styrene / acrylonitrile copoly obtained merisat had an acrylonitrile content of 27% by weight, based on the copolymer, and a viscosity number of 80 ml / g.

Comparative Example 1

ABS polymer

A polybutadiene rubber which was grafted with a styrene-acrylonitrile copolymer as component (A), which was present in a styrene-acrylonitrile copolymer matrix as component (B), was used as the comparative polymer. The graft rubber content was 30% by weight, based on the total weight of the finished polymer.

Example 9

Component C

A conventional polycarbonate (PC) was used as component C, which had a viscosity number of 61.5 ml / g, determined in the solvent methylene chloride. According to the information in Table 1 below, the stated amounts of the corresponding polymers (A), (B) and (C) or the comparative compositions are mixed in a screw extruder at a temperature of 250 ° C. to 280 ° C. Moldings were produced from the molding compositions formed in this way.

The composition of the molding compounds is shown in the table below:

Table I

Test results:

a: scratch resistance

The scratch resistance is determined using a CSEM Automatic Scratch Tester model AMI (manufacturer: Center Suisse d'Electronique et de Micro technique S.A.). The scratch tester has a diamond tip with a 120 ° tip angle and 0.2 mm radius. With this diamond tip, scratches of 5 mm in length are introduced into injection-molded test specimens from the material to be tested. The contact pressure of the diamond, unless otherwise stated, is 2.6 N. After an hour of waiting, the scratches that are created are scanned in the transverse direction and displayed as a height-depth profile. The scratch depth can then be read from this.

b: Stress crack resistance

The resistance to stress cracking is determined using the bending strip method in accordance with ISO 4599. The test specimens used are injection molded. They have the dimensions 80 x 15 x 2 mm. Unless otherwise stated, the test specimen was worked with a bending radius of 50 mm. For this purpose, the test specimens were clamped in a template, bent and wetted with the test medium for 24 hours. Then the impact work at break is determined with a pendulum. Bl isopropanol was used as the test medium. A normal household cleaner (Ajax Ultra Classic® from Colgate Palmolive Germany, a surfactant household cleaner) was used in b2.

c: swelling

To measure swelling, injection-molded shoulder bars (tensile bars according to ISO 3167 with a thickness of 4 mm) are placed in the medium to be tested for 96 h stored. Then they are superficially dried, and the change in weight and, if necessary, the change in tensile modulus (determined according to ISO 527) are determined in comparison with the initial value. Table II, cl shows the change in weight in methanol, in c2 in super gasoline and in c3 the change in tensile modulus in super gasoline.

permeability

To test the permeability, foils are pressed from the material to be tested (thickness approx. 120 to 250 μm), the permeability of which to the specified gases or liquids is determined at 23 ° C. The values are given in (cm ³ 100 μm) / (m ² d bar) for gases or in (g 100 μm) / (m ² d) for water (Table IH).

Molding compositions that can be used advantageously should meet the following conditions: scratch depth of less than 6 μm, change in impact energy compared to the initial value of less than 10%, swelling in methanol of less than 1% or swelling and change in the modulus of elasticity of less than 6 % in super gasoline.

The results are shown in Tables II and HI below.

Table π

In addition, the swelling was investigated on the molding compound 1H and the comparative molding compound VE with different exposure times. The results are shown in Table IV below:

Table IV Swelling (weight change) in methanol and premium gasoline

Furthermore, the fogging behavior according to VW-PV 3015, method B (100 ° C., 16 h) was investigated for the molding compound DI and the comparative molding compound NU. No noteworthy quantities could be analyzed.

The molding compositions with a polycarbonate content of more than 50% by weight had an excellent combination of properties. This advantageous range of properties makes them particularly suitable for use in the housings of electrical transformers containing small transformers.

Claims

claims

1. Use of a thermoplastic molding composition other than ABS, comprising, based on the sum of the amounts of components A, B, C and optionally D, which gives a total of 100% by weight,

a: 1-48% by weight of at least one single-phase or multi-phase particulate emulsion polymer with a glass transition temperature below 0 ° C. in at least one phase and an average particle size of 50-1000 nm, as component A,

b: 1-48% by weight of at least one amorphous or partially crystalline

Polymer as component B,

c: 51-98% by weight of polycarbonates as component C, and

d: 0-47% by weight of conventional additives and / or fibrous or particulate fillers or mixtures thereof as component D.

for the manufacture of housings and their semi-finished products from electrical transformers containing small transformers.

2. Use according to claim 1, characterized in that component A is a multi-phase polymer from

al: 1-99 wt .-% of a particulate first phase AI with a

Glass transition temperature below 0 ° C,

a2: 1-99% by weight of a second phase A2 from the monomers, based on A2, a21: 40-100% by weight of units of a vinyl aromatic monomer as component A21 and

a22: 0 to 60% by weight of units of an ethylenically unsaturated monomer as component A22,

3. Use according to claim 2, characterized in that the molding composition contains as a particulate first phase AI an acrylate, EP, EPDM or silicone rubber.

4. Use according to claim 3, characterized in that component AI consists of the monomers

all: 80-99.99% by weight of a C 8 _-8- alkyl ester of acrylic acid as component All,

al2: 0.01-20% by weight of at least one polyfunctional crosslinking monomer as component A12.

5. Use according to one of claims 1 to 4, characterized in that the particle size distribution of component A is bimodal, 1-99% by weight having an average particle size of 50-200 nm and 1-99% by weight having an average particle size have from 200 to 1000 nm, based on the total weight of component A.

6. Use according to one of claims 1 to 5, characterized in that the housings essentially only contain a small transformer.

7. Use according to one of claims 1 to 6, characterized in that the electrical devices are power supplies or chargers for batteries.

8. Housing of small transformers-containing electrical devices made of a thermoplastic molding composition, as defined in one of claims 1 to 5.

9. Housing according to claim 8, characterized in that the electrical devices are power supplies or chargers for accumulators.

10. Use according to one of claims 1 to 5 for the production of semi-finished products, profiles, tubes, foils and plates which are processed to produce the housing.