NL8701208A - Polymer compsn. to improve miscibility of synthetic resins - contains ethylene!- propylene!-diene! rubbers, ethylene! vinyl! acetate copolymers, and other polymers - Google Patents

Abstract

A polymer compsn. comprises (a) 30-70 pts.wt. of one or more ethylene-propylene-diene rubbers (pref. having green strength), (b) 30-70 pts.wt. of one or more ethylene-vinyl acetate copolymers with a vinyl acetate content of 18-40 wt.% and (c) 1-25 pts.wt. of one or more other polymers. prodn. of above polymer compsn. comprises supplying to the intake zone of an extruder (a) (b), (c) above and (d) opt. one or more other polymeric and non-polymeric additives and reacting them, with mixing, at elevated temp. (pref. at least 150 deg.C), discharging the prod. from the extruder, cooling and granulating it. A moulding compsn. comprises (pref. 65-99.9 wt.% of) at least one thermoplastic synthetic resin (or a mixt. contg. same) and/or at least one elastomer and (pref. 0.1-30 wt.% more pref. 0.5-10 wt.% partic. 1.0-5 wt.%, of) above polymer compsn., (and opt. 0-5 wt.% additives). A colour master batch for colouring synthetic resins comprises above polymer compsn.. An articles of mfr. made from above moulding compsn. is also claimed.

Description

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VO 9177

Thermoplastic molding compound.

The invention relates to a thermoplastic molding compound based on at least one thermoplastic plastic.

It is known in the plastics industries that polymers are generally not compatible with one another. Intolerance is the rule, while tolerance only occurs exceptionally. However, because there is a continuing need for plastics for all kinds of new applications, while the number of truly new plastics is very limited, there is an increasing search for mixtures of plastics in order to combine certain desired properties of the different plastics. Due to the intolerance of the plastics with each other, it is often the case that in a plastic mixture one does not get the sum of only the good properties, but usually just the sum of the bad properties of both components, while the good properties are lost. .

Much work has been done to find polymers that are compatible with one another in certain proportions in compositions. One can think of modifying one of the components or both components. Another approach to obtaining compatibility is to add an additional component that is compatible with both polymers and functions as a kind of polymeric emulsifier.

In certain cases, when mixing polymers, it is preferable that no compatibility between the components occurs, but rather that they exist in different phases, since one of the phases is intended to be continuous, while the other 87012G8 4 * k -2- phase in the form of discontinuous particles remains. This situation mainly occurs in the manufacture of rubber-reinforced plastics, in which one has a continuous thermoplastic matrix phase, in which finely divided rubber is present. If the adhesion between the matrix phase and the rubber particles is sufficiently great, a particularly strong increase in the mechanical properties such as impact strength and the like occurs when the rubber is incorporated in the matrix phase. Known examples of such polymer compositions are ABS, impact resistant polystyrene, rubber modified nylons and the like. However, a prerequisite for obtaining good impact strength is that there is chemical or physical adhesion of the dispersed rubber phase to the continuous matrix phase. In the known rubber-modified styrene polymers, this is achieved by grafting monomers corresponding to the monomers that form the polymer of the continuous matrix phase onto the rubber particles. As a result, a kind of anchoring of the disperse rubber phase occurs. Another approach to obtaining this adhesion is to use an auxiliary agent which acts as a polymeric emulsifier, e.g. as described in U.S. Patents 4,341,884 and 4,341,885.

25 A comprehensive overview of the principles of impact-resistant plastics modification is given in Bucknall's handbook, Toughened Plastics (1977), Applied Science Publ. Ltd.

In mixtures of plastics it can be advantageous if the various components are mixed together on a molecular scale, i.e. that discrete particles can no longer be distinguished. On the one hand this may mean that there is complete mixing, but it may also be that an "interpenetrating network" 35 is present, i.e. that the various components each form a continuous network.

8701 20 8 ί »-3-

From the viewpoint of product composition and application flexibility, it is of course preferred to use additives to the polymer system, as they may have the advantage of being useful over a wider range of ratios and polymers. Until now, however, the problem has always arisen that it was not possible to improve the compatibility of all kinds of polymers, regardless of their composition, on the basis of one product.

The invention is characterized by a thermoplastic molding compound, comprising at least one thermoplastic plastic and a polymer composition based on a) one or more ethylene-propylene diene rubbers, and b) one or more ethylene-vinyl acetate copolymers with a vinyl acetate content of 18-40 wt. .%, obtained by reaction at elevated temperatures of components a) and b) in a weight ratio of 2.5: 1 and 1: 2.5.

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The thermoplastic plastic component of said molding compound can be virtually any thermoplastic plastic, whether the plastic is pure, or mixed with one or more other thermoplastic plastics, or rubbers. Suitable plastics are polyolefins such as high and low density polyethylene and polypropylene, polystyrene and styrene polymers such as SAN, ABS and SBS, polyesters such as polyethylene terephthalate, and ΡβΤΡ polyamides such as nylon 6, nylon 66, nylon 46, nylon 612, aramid, polycarbonate, polyetherimide and the like. By adding the polymer composition to these plastics as such, there is generally a marked improvement in many properties of the plastic, such as flow, mechanical properties and extruder yield.

However, the effect can still be much more clear if one starts from mixtures of two or more plastics, either thermoplastic plastics or a thermoplastic plastics with a rubber, the presence of the polymer composition according to the invention permitting plastics with to mix and process into a homogeneous mixture which has hitherto been considered completely intolerant. One can e.g. think of mixtures of polypropylene and high-density polyethylene, polypropylene 10 and polystyrene, polypropylene and PVC, which may or may not have been plasticized.

A major advantage of the invention is that it is possible to modify PP with HDPE, whereby a product with good low temperature properties, such as impact resistance at low temperature, can be obtained. Virtually all copolymer types can be replaced in this way with one type of PP.

Blends of PP (raffia grade) with LDPE and the polymer composition according to the invention have particularly good yarn properties, which make it possible to use this product for a large number of applications for which originally PP was completely unsuitable.

According to a preferred embodiment of the invention, the molding composition consists of 90-99 parts by weight of PVC, 1-10 parts by weight of the polymer composition, and up to 5 parts by weight of conventional additives. It has surprisingly been found that no processing problems occur at all with this molding compound. It is known, for example, that PVC is quite difficult to process, partly because it is very sensitive to combustion. With the molding material according to the invention this phenomenon is not at all. On the contrary, it is possible to load PVC to very high temperatures without any form of combustion occurring. PVC can therefore also be mixed in ABS to high-impact, flame-retardant 8701208 -5-.

ABS-PVC mixtures, which was not or hardly possible until now.

An additional advantage of the molding compound according to the invention on the basis of PVC is that the splitting resistance and impact resistance are greatly improved. It is now possible to nail PVC without this product splitting. This is particularly important for corrugated sheets or roofing sheets.

Surprisingly, it has furthermore been found that the molding composition according to this embodiment of the invention has no static charge at all, which is of great importance in particular for the production of gramophone records.

Another embodiment of the invention relates to a molding compound with barrier properties. Such a molding compound is characterized in that it mainly consists of a mixture of 1) 60-95 parts by weight of a thermoplastic plastic, which has substantially no gas-barrier properties, 2) 5-40 parts by weight of a plastic which imparts gas barrier properties, and 3) 0.5-10 parts by weight of the polymer composition.

Preferably, the thermoplastic plastic 1) is selected from ABS, LLDPE, LDPE, HDPE and PP, while the plastic 2) is selected from nylon 6, PBTP and PETP.

More specifically, the gas barrier property component is present in an amount of 5-40% by weight, based on the total molding mass. Only in the case of the combination of ABS-nylon 6 the amount of ABS is limited to a maximum of about 35% by weight, because it is not or very difficult to obtain a good dispersion at higher contents of ABS.

In particular, it is preferred to combine LDPE and / or LLDPE with nylon 6 to yield a product from which a one-layer barrier film or container can be made. By using such a molding compound according to the invention, the necessity of making laminates 8701208-6 has completely disappeared. In addition, a foil made from such a molding compound is readily weldable.

In this context, the term "gas barrier properties" means an O2 permeability of less than about 50 cm 3 mm m "2 d" 1 bar "1, while products with values greater than 100 are considered to be essentially no gas barrier possess properties.

According to another embodiment of the invention, the molding composition consists of polypropylene or a propylene-ethylene copolymer with an ethylene content of 5-40 mol, polystyrene or SBS and the said polymer composition in a preferred ratio of 60-85: 15-40, respectively. : 1-10, as parts by weight. Surprisingly, it has been found that such molding compositions have excellent impact resistance, especially at low temperature (-20 ° C), combined with good stiffness.

A last preferred embodiment of the invention relates to flame-retardant molding compositions based on polyolefins and chlorine-containing polymers. In combination with the polymer composition, LDPE, LLDPE, HDPE, and polypropylene (which also includes copolymers) can be mixed with PVC, Cl-PVC and / or Cl-PE, to form a tolerant mixture with good flame-retardant properties on the one hand and in principle on the other hand the basic properties of the starting product. Suitable contents of the chlorine-containing polymer are mainly determined by the desired flame-extinguishing properties, but will generally be between 10 and 25% by weight, based on the final product.

The polymer composition based on an ethylene-propylene-diene rubber and an ethylene-vinyl acetate copolymer is used in all molding compositions according to the invention, and is responsible for the special properties of the molding compositions.

This polymer composition is based on a) one or more ethylene-propylene diene rubbers, and 8701208

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-7- b) one or more ethylene-vinyl acetate copolymers with a vinyl acetate content of 18-40% by weight, the weight ratio of ethylene-propylene-diene rubber to ethylene-vinyl acetate copolymer being between 2.5: 1 and 1: 2.5.

In another embodiment of the invention, the polymer composition comprises a product based on a) one or more ethylene-propylene diene rubbers, and b) one or more ethylene-vinyl acetate copolymers having a vinyl acetate content of 18-40% by weight, obtained by reaction at elevated temperature of components a) and b) in a weight ratio of 2.5: 1 and 1: 2.5, optionally in the presence of one or more other polymeric and non-polymeric components.

According to a preferred embodiment of the invention, two different ethylene-propylene diene rubbers are used as component a). The differences between these rubbers can be in various aspects, such as ethylene content, propylene content, diene content, nature of the diene, such as dicyclopentadiene, ethylidene norbornene or 1,4-hexadiene, Mooney viscosity of the rubber, distribution of the monomers over the rubber, which aspects are eg can express in the greater or lesser degree of green strength, i.e., the strength in the unvulcanized state. The use of at least one rubber which has a reasonable green strength is preferred, since it achieves better properties of the final product into which the polymer composition 30 is incorporated.

The preparation of such rubbers is known (Ullmann, Encyklopadie der Technischeen Chemie, 4. Auflage,

Band 13, p. 619-621). Mainly vanadium-based catalysts are used. The degree of unsaturation can be adjusted by controlling the content of diene. Usual values for this are 3-20 double 8701208 -8 bonds per 1000 C atoms. The Mooney viscosity is generally between 30 and 125 (1-4 / 100 ° C).

The ethylene content of the rubbers can be between 45 and 80% by weight.

Preferably, as component b), an ethylene-vinyl acetate copolymer with a vinyl acetate content of between 25 and 30% by weight is used. A vinyl acetate content within this range is preferred, since the degree of improvement of properties is strongest at a vinyl acetate content in this range.

An explanation for this is currently not available, but it has been found that at differing levels of vinyl acetate, either the universal usability of the product or the impact strength of the resulting final product suffers.

The ethylene-vinyl acetate copolymers are usually prepared by a high pressure process in which a radical polymerization is carried out using pressures above 1000 bar.

Preferred EVA copolymers have a melt index of 0.5 to 25.

For certain very specific applications, it is preferable to include a rubber as component c) in the polymer composition. The ratio of component a) to component c) is generally between 100: 1-1: 1, i.e. the other rubber is maximally present in the same amount as the EPDM rubber or rubbers. However, it is preferred to use a more minor amount of other rubber, with an optimum value being between 5: 1 and 1.5: 1.

An advantage of the inclusion of such a rubber lies in the improvement of its anti-delamination effect in particularly intolerant polymers. Examples of suitable rubbers are styrene butadiene rubber, styrene butadiene block copolymers (SBS), butadiene acrylic onitrile rubber, butyl rubber, isoprene rubber, polybutadiene 8701208-9 rubber and the like. Such rubbers are well known and commercially available.

The polymer composition preferably contains one or more waxes, which have a positive influence on the flow behavior, the mold release and the like. Suitable waxes are polyolefin waxes, more particularly polypropylene waxes, which are often low molecular weight amorphous polypropylene.

Most preferably, two or more polypropylene waxes are used in combination, the melt flow indices of these waxes being different. By such a choice of waxes to be added, an optimum polymer composition is obtained, with a clearly improved property pattern.

Such polyolefin waxes, in particular polypropylene waxes, are known and commercially available. Melt flow indices used are between about 10 and 300.

The polymer composition of the invention can, as mentioned, contain various types of EPDM rubber, it being particularly preferred that one or more of the types used is a green strength rubber.

The usual commercially available rubbers can be used per se for the ethylene-propylene diene rubbers. Preferably, one or more heat stabilizers and one or more antioxidants are included in the polymer composition. Suitable compounds for this are the thiopropionates, such as DLTDP or DSTDP, and phenolic antioxidants. However, it is also possible to use other compounds which have the desired effect.

It is not entirely clear why the polymer composition according to the invention on the basis of the ethylene-propylene-diene rubber and the copolymer of ethylene and vinyl acetate has the unique combination of properties found. It is suspected that when preparing the polymer composition under the mixing conditions, such as 8701208 4 -10 pressure, temperature and residence time, a reaction occurs between the ethylene-propylene diene rubber on the one hand, and the copolymer on the other, under formation of a kind of adduct. However, this in itself would not fully explain the particularly good properties of the polymer composition.

Preferably, the polymer composition is prepared by feeding the various components to the retraction zone of an extruder, then mixing at a temperature of at least 175 ° C, preferably for part of the residence time in the extruder of at least 200 ° C, but not more than 300 ° C, then cooling and granulating the product obtained.

The products preferably used in the process, and the amounts thereof have already been discussed in detail above, and also apply mutatis mutandis to the process.

The molding composition according to the invention can be prepared in various ways, using known methods. In general, the various components, namely thermoplastic plastic (s), polymer composition and any other additives or components, will be supplied to a mixer, such as a Henschel, a Banbury, a single or twin screw extruder, rollers, etc., and there at elevated temperature. to blend. It has been found that the presence of the polymer composition greatly facilitates mixing so that use of intensive mixers is possible, but not necessary.

In the molding composition according to the invention, the usual additives are used, such as fillers, pigments, dyes, antioxidants, stabilizers, lubricants, mold release agents and the like, although substances of the latter two categories are generally superfluous due to the excellent action of the polymer composition .

The invention is now explained with reference to 8701 208

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sf -11- of some examples, which are not to be construed as limiting the invention.

Example I

50 parts were added to a twin screw extruder.

Ethylene-propylene-diene rubber (25 parts by weight of EPDM with ethylene content of 55% by weight, ethylidene norbornene and dicyclopenta-diene as the diene component; 25 parts by weight of EPDM with ethylene content of 70% by weight, dicyclopentadiene as diene component), 48 parts by weight. ethylene-vinyl acetate copolymer with 28 wt% 10 VA, and a melt flow index of 9, and 2 parts by weight. polypropylene wax (mixture of melt flow index waxes of 20 and 200) supplied along with Irganox 1076.

In the extruder, these components were mixed and reacted at a temperature of 225 ° C; then the mixture was extruded and granulated.

Example II

In the same manner as in Example 1, the components mentioned therein, together with 25 parts by weight, were added.

SBS fed to the extruder, and further processed in the manner described.

Example III

The procedure of Example II was repeated, replacing 25 parts by weight. SBS 25 parts of butadiene-acrylonitrile rubber was used.

Example IV

96 parts by weight of commercially available PVC and 4 parts by weight. of the product of Example I, commercially available under the trade name Bennet from HTP B.V., were mixed at 260 ° C and extruded into corrugated sheet.

The product obtained was impact resistant and could be nailed without problems. Also, no trace of combustion was observed, despite the - especially for PVC - very extreme conditions.

35 Example V

98 parts. carbon black-colored PVC for the manufacture of gramophone records was mixed with 2 parts by weight at 260 ° C. Bennet. Gramophone records were pressed from the resulting mixture. These had excellent sound quality and were completely anti-static. No bulging occurred during production, which is responsible for approximately 2% production loss in the conventional products.

Example VI

Based on 70 parts by weight. commercially available 10 high density polyethylene, and 30 parts by weight. commercially available nylon 6 and 4 parts by weight. of the product of Example 1, a mixture was prepared at a temperature of 260 ° C, which mixture was found to be homogeneously mixed. Injection molded containers with thick walls, for example beer kegs, had good gas barrier properties.

Examples VII and VIII

Based on 70 parts by weight. low density polyethylene, 30 parts by weight. nylon 6 and 4 parts by weight. of the product of Example 1 and 90 parts by weight, respectively. low density polyethylene, 10 parts by weight. nylon 6 and 4 parts by weight. Two synthetic mixtures were made from the product of Example I. The mixtures were mixed at 260 ° C. and both could be processed excellently. The mixture 25 with 70 parts by weight. LDPE was particularly suitable for thick-walled containers, such as beer kegs, while the mixture was 90 parts by weight. LDPE could be processed into foil and thin-walled containers, such as bottles. The products based on both mixtures had excellent gas barrier properties.

Example IX

70 parts by weight. propylene homopolymer, 30 parts by weight.

PBTP and 4 parts by weight. of the product of Example I were mixed at 260 ° C and injection molded into bottles and thick-walled containers. The products were excellent in injection molding and had good gas barrier properties. Example X.

70 parts by weight. nylon 6.30 parts by weight. ABS and 4 parts by weight.

8701208-13 of the product of Example 1 were mixed.

The resulting mixture was homogeneous and was used for injection molding automotive parts at a temperature of 260 ° C. Despite the extreme conditions 5, no degradation of ABS occurred.

Example XI and comparative example I.

Commercially available ABS was injected into a number plate holder mold at the usual processing temperature. The screw configuration and the die construction were found to be such that the die could not be filled completely (Comparative Example I).

The same ABS, to which, however, 1% by weight of the product of Example I was added, could be sprayed without any problems, while excellent products were obtained. The mold was completely filled.

Example XII

Extruding ultra high molecular weight polyethylene to foil, to which 3% by weight of the product of Example 1 was added, it was found that the head pressure in the extruder and the power required were reduced relative to the product without addition, that the production could be increased by 25% without any deterioration in product quality. Example XIII

At a temperature of 260 ° C, 15 parts by weight.

PVC, 85 parts. propylene homopolymer, and 4 parts by weight. of the product of Example 1 mixed and injection molded into test pieces. These rods were incinerated with a flame. The product was extinguished after the flame had been removed.

Examples XIV and XV

A mixture based on 70 parts by weight. polypropylene, 30 parts by weight. polystyrene and 5 parts by weight. The product of Example 1 was injection molded into test strips of 6.05 mm thickness. These rods were tested for impact resistance at -20 ° C, whereby a value of 12.9 mJ / mm2 870 (208 if 4 -14- was obtained. This value is so high that this product can be used without any problem for manufacturing. of road posts, which must have good mechanical properties under very extreme temperature conditions, both low and high temperature.

76 parts by weight. of a copolymer of propylene with ethylene, 19 parts. SBS and 5 parts by weight. of the product of Example 1 were processed into test bars in the same manner as above. The impact strength of this product was 12.8 mJ / mm 2.

Example XVI

The same propylene copolymer with ethylene used according to example XV was mixed with 5% of the product according to example I. The impact strength at -20 ° C was 8.4 mJ / mm 2.

8701208

Claims (12)

Thermoplastic molding compound comprising at least one thermoplastic plastic and a polymer composition based on a) one or more ethylene-propylene diene rubbers, and b) one or more ethylene-vinyl acetate copolymers with a vinyl acetate content of 18-40% by weight, obtained by reaction at elevated temperature of components a) and b) in a weight ratio of 2.5: 1 and 1: 2.5. Molding compound according to claim 1, characterized in that the content of the polymer composition is at least 0.5% by weight. Molding compound according to claim 2, characterized in that the content is between 0.5 and 10, more particularly between 1.0 and 5% by weight. Molding compound according to claims 1-3, characterized in that as thermoplastic plastic component one or more plastics are used selected from the group consisting of PVC, LDPE, LLDPE, HDPE, PP, ethylene propylene copolymers, polystyrene, ABS, SAN, nylon 6, nylon 6-6, nylon 6-12, nylon 4-6, PETP, PBTP, SBS and polycarbonate. Molding compound according to claims 1-4, characterized in that it mainly consists of 90-99 parts by weight. PVC, 1-10 parts by weight. of the polymer composition and up to 5 parts by weight. usual additives. 6. Molding compound according to claims 1-4, characterized in that it mainly consists of a mixture of 1) 60-95 parts by weight. of a thermoplastic plastic which has substantially no gas barrier properties, 2) 5-40 parts by weight. of a plastic which imparts gas barrier properties, and 3) 0.5-10 parts by weight of the polymer composition. Molding compound according to claim 6, characterized in that the thermoplastic plastic 1) is selected from ABS, LLDPE, LDPE, HDPE and PP. 8701 2.08. if -16- Molding compound according to claim 6 or 7, characterized in that the plastic 2) is selected from nylon 6, PBTP and PETP. 9. Molding composition according to claims 6-8, characterized in that it mainly consists of 1) LDPE and / or LLDPE, 2. nylon 6 and 3) the polymer composition. Molding composition according to claims 1 to 4, characterized in that it consists of a propylene homo- or copolymer, polystyrene or SBS and the polymer composition. Molding compound according to Claims 1 to 4, characterized in that the thermoplastic plastic component mainly consists of a polyolefin mixed with a chlorine-containing polymer. Molding material according to claim 11, characterized in that the chlorine-containing polymer is selected from PVC, Cl-PVC and chlorinated polyethylene. 870 | 208