(54) ACRYLONITRILE-BUTADIENE-STYRENE RESIN/ POLYVINYLIDENE FLUORIDE RESIN COMPOSITE MATERIAL(71) We, PRODUITS CHIMIQUES UGINE KUHLMANN, a French Body Corporate of 25 boulevard de l'Amiral Bruix, 75116 Paris, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:The present invention relates to a composite material formed by an acrylonitrilebutadiene-styrene terpolymer, generally known as ABS, covered by polyvinylidene fluoride, generally known as PVF2.
According to the present invention there is provided a composite material having improved mechanical properties after ageing, the said material comprising, as the main constituent, an acrylonitrile-butadiene-styrene terpolymer, and adhered to at least one of the major surfaces of the main constituent a coating of a polyvinylidene fluoride containing an inorganic or organic filler as protection against ultra-violet radiation. According to the invention, the organic or inorganic filler is combined with the PVF2 for the purpose of forming a barrier against ultra-violet rays. Such a material exhibits a resistance to chemical agents and possesses mechanical properties after ageing, in particular resistance to shock and elongation in tension, which are superior to those of the ABS.
The resistance to ageing of ABS in inclement weather or in a corrosive atmosphere is mediocre. A number of protective coverings have been proposed consisting of other polymers more resistant than the ABS, for example an acrylic resin, polyvinyl chloride or a polycarbonate. These measures, far from providing effective protection for the ABS, have, in some cases, the disadvantage of impairing the mechanical properties of the resultant material. Surprisingly the use of PVF2 combined with an organic or inorganic filler to act as a barrier against ultra-violet radiation in accordance with the present invention gives a composite material of substantially improved properties.
The PVF2 covering containing an inorganic or organic filler is generally of a thickness at most ten times less than the thickness of the ABS constituent but the thickness of the covering must not be greater than 400 microns and preferably more than 100 microns.
This covering may take the form of a thin layer or film prepared by the conventional methods. For example the filler may be mixed with the PVF2 in solution in a solvent and the resultant mixture coated on a transfer paper so as to obtain a film of the required thickness after evaporation of the solvent. Polyvinylidene fluoride resin is suitable for the production of this covering, this term being understood to include pure PVF2 and copolymers containing at least 70% by weight of PVF2.
The inorganic or organic filler which can be used is well known to the man skilled in the art, and can be any product in current use as an anti-ultra-violet barrier in thermoplastics. It may be an inorganic filler such as for example a metallic oxide or salt, or a powder of a compound or of a metal such as zinc oxide, titanium oxide, silica, talc, barium sulphate, calcium carbonate, a silico-aluminate, aluminium, copper or bronze powders. It may also be an organic filler such as for example a simple pigment or a commercial ultra-violet absorbing agent such as one based on a benzophenone,a benzotriazole, a substituted amine or a salicylate. The filler may be used alone or it may be a mixture. In general if desired the PVF2 covering may optionally contain 0.01 to 50%by weight of inorganic filler or 0.1 to 10% by weight organic filler.
The ABS constituent which is suitable for the production of the composite material is conventional. It may be prepared from the product obtained by polymerisation of a mixture of an olefinic nitrile and a vinylic aromatic hydrocarbon, for example the mixture acrylonitrilc-styrene or alphamethylstyrene in the presence of a polybutadiene. The terpolymer is generally prepared from 5 to 40% by weight acrylonitrile, 30 to 80% by weight styrene and 10 to 60% by weight polybutadiene. The ABS may contain all the common additives for this type of resin, for example fillers, pigments, plasticisers and protective agents.
The composite material may be manufactured by the methods which are known for making thermoplastic elements adhere intimately. An interesting manufacturing process described inFrench patent application 77/09.917 consists in depositing a fine layer of polyurethane on the surface of the PVF2/filler layer which is to be adhered to the ABS by using a solution of polyurethane in an aprotic polar solvent. The material is then heated at a temperature of from 1 200C to 3000C for a few minutes in order to remove the solvent. After cooling, the surface of the PVF2/filler layer treated with polyurethane is applied to the ABS constituent and the assembly is adhered by hot-die sealing.
The composite material of the present invention has special characteristics in particular improved shock resistance and elongation in tension after ageing. These properties may sometimes be twice as good as the ABS constituent which is aged under the same conditions.
Thus it can be utilized for the manufacture of products requiring good behaviour with respect to ageing. its application is envisaged for the manufacture, for example, of boat hulls, components of vehicle bodies, internal linings of refrigerators and freezer chests and frontage pancls for buildings.
The present invention is illustrated by the following Examples.
Ageing of the composite material is accelerated in order to check its mechanical properties by mcans of a Xenotest 450 apparatus. The speciments are kept at around 25"C for at least 100 hours in an atmosphere of which the relative humidity of the air is 65% with water sprinkling for 5 minutes every 30 minutes. This test corresponds to the method of executing the test laid down by the designer of the Xenotest 450. As an indication, it is estimated that to be equivalent with exposure to the outside in bad weather the durations under Xenotest 450 should be multiplied by 10.
Rcsults of shock resistance tests by the Dynstat method, in which the covered surface is struck by a pcndulum are given as the average value of 10 test pieces for each exposure period. The dimcnsions of the test pieces are 50 x 10 mm multiplied by the thickness in mm of the composite material.
The tests for elongation in tension are carried out according to the standard ASTM-D 638.58 on test pieces machined from the composite material.
EXAMPLE ITo a solution of PVF2 in dimethyl formamide there is incorporated 3% by weight of TiO2 relative to the weight of PVF2, the dry extract of the whole being 20% by weight. This composition is coated on a transfer paper so as to obtain, after evaporation of the solvent at 140"C, a film with a thickness of 25 microns and a film with a thickness of 50 microns.
By way of comparison a film of PVF2 without TiO2 is prepared which has a thickness of 25 microns.
On one of the faces of each of the three films there is sprayed a 15% by weight solution of solid polyester polyurethane (DESMOCOLL 500 by BAYER) in dimethyl acetamide. The solvent is evaporated, the films being kept for 5 minutes at 1500C in a ventilated oven.
The faces of the films which have been so treated are applied to a sheet of ABS (UGIKRAL S.E. by PRODUITS CHIMIQUES UGINE KUHLMANN) 3 mm thick and stuck together in a press at a temperature of 1700C.
Again, by way of comparison, there is stuck on a sheet of ABS under the above-described conditions a film. 50 microns thick, based on methyl polymethacrylate (PMMA) with a 3%by weight filling of TiO2.
The resultant composite materials are aged under the previously mentioned conditions.
The results of the shock resistance and elongation in tension tests are given in the following tables. The results obtained on the non-coated sheet of ABS are also given for comparison.
Shock resistance expressed in % ofDuration the initial value at time 0of Composite materialexposure(hours) ABS (PVF2 + TiO2) (PVF2 + TiO2) PVF2 (PMMA + TiO2) 25u 50p 25 50u0 100 100 100 100 100100 32 98 100 54 70500 28 89 95 34 351,000 24 68 86 30 302,000 23 40 70 - 25Elongation at break, expressed in %Durationof Composite materialexposure(hours) ABS (PVF2 + TiO2) (PVF2 + TiO2) PVF2 (PMMA + TiO2) 25u 50,u 25u 50u 0 30 28 29 28 27100 15 28 28 22 25500 10 25 26 14 201,000 7 20 23 9 132,000 4 18 - 7 10EXAMPLE 2Under the same manufacturing conditions as for Example 1 three composite materials are prepared on the basis of ABS 3mm thick and PVF2 in which the TiO2 filling is replaced by: a) 10% by weight of zinc oxide relative to the weight of the PVF2.
b) a mixture of anti-ultra-violet agents comprising, by weight relative to the weight of thePVF21% of a compound based on substituted benzotriazole (TINUVIN P)and 0.6% of a steric hindrance substituted amine (TINUVIN 770),c) a mixture of the following, calculated by weight relative to the weight of the PVF2:1.5% cadmium red (Red 125 FBA)and 1% red iron oxide (Red 720).
The results of the tests for shock resistance and elongation in tension after ageing are given in the table below.
Durationof Sample a Sample b Sample cexposure (h)Thickness of PVF2 coat 2Sp 25u 50,u Shock resistances after 0 100 100 100ageing in % of initial 100 98 97 89value at time 0 500 81 93 791,000 64 66 53ASTM- TENSION 0 25 29 29Elongation at break 100 24 27 25after ageing 500 21 23 19expressed in % 1,000 17 19 15EXAMPLE 3To a solution of PVF2 in dimethyl formamide there is incorporated 2 % by weight of carbon black (Black 900), based on the weight of the PVF2, the dry extract of the whole being 20% by weight. This composition is spread on a transfer paper under the conditions of Example 1 so that after evaporation of the solvent a film 25 microns thick is obtained.
Still under the conditions of Example 1, one of the faces of the film is treated with a 15 by weight solution of solid polyester polyurethane in dimethyl acetamide.
Furthermore, a non-pigmented ABS (UGIKRAL SE by Produits Chimiques UgineKuhlmann) is extruded on a single-screw machine with a diameter of 90 mm and a length of 20 diameters, fitted with a flat die-plate 700 mm wide and regulated so as to give a sheet 5 mm thick, the machine temperatures ranging in stages from 200 to 400"C, the die-plate being regulated at 2 1 OOC. The rotational speed of the screw is regulated at 30 r.p.m. and the output is 120 kg/hour.
The previously obtained film of PVF2 is unrolled at ambient temperature and the treated face is applied to the ABS continuously by means of the polishing train of the extrusion line, the rolls of which are regulated at temperatures ranging in stages from 90 to 1100C.
The results of the tests for shock resistance and elongation in tension after ageing of the resultant composite material are given in the table below.
Duration of Shock resistances Elongations at breakexposure (h) after ageing in % expressed in 96 initial value at time O 0 100 35100 97 32500 92 311,000 72 26The words "Desmocoll" and "Tinuvin" used in this specification are registered TradeMarks.
WHAT WE CLAIM IS:1. A composite material having improved mechanical properties after ageing, the said material comprising. as the main constituent, an acrylonitrile-butadiene-styrene terpolymer, and adhered to at least one of the major surfaces of the main constituent a coating of a polyvinylidene fluoride containing an inorganic or organic filler as protection against ultraviolet radiation.
2. A material according to Claim 1, wherein the maximum thickness of the polyvinylidene fluoride coating is ten times less than the thickness of the ABS terpolymerconstituent and the thickness of the said coating is not more than 400 microns.
3. A material according to Claim 2, wherein the thickness of the polyvinylidene fluoride
**WARNING** end of DESC field may overlap start of CLMS **.