GB1600895A - Silicate filled polyolefin resin compositions - Google Patents

Description

(54) SILICATE FILLED POLYOLEFIN RESIN COMPOSITIONS (71) We, FORD MOTOR COMPANY LIMITED, of Eagle Way, Brentwood, Essex, CM13 3BW, a British Company, 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: This invention relates to silicate filled resin compositions made with additives which comprise chlorinated aliphatic compounds. Inclusion of these additives can enhance mechanical properties of the composites.

Coupling additives for certain inorganic filled resin compositions are known. For example, silane compounds are employed in various silicate filled resin composites for improving resin reinforcement by the silicate. Moreover, certain chlorinated aliphatic compounds have been utilized in resin systems to aid in fire retardancy.

It has been now discovered that certain chlorinated aliphatic compounds act to improve silicate and polyolefin resin adhesion especially when select melt times and temperatures are used during processing.

This invention provides compositions which comprise a silicate filler (e.g., mica), a polyolefin resin, and a minor amount by weight based on the combined weight of the filler and resin of an additive which comprises one or more chlorinated hydrocarbon waxes with a molecular weight of from 250 to 10,000 and which contains from 5 to 80% by weight chlorine.

The invention also includes a filler material suitable for improving the strength of polyolefin resin compositions comprising a blend of the silicate filler and additive defined in the preceding paragraph.

The invention still further includes a process for making a mouldable material comprising the steps of melting a composition in accordance with the invention and maintaining the composition at a temperature and for a time sufficient to improve its strength.

Preferably the additive has a molecular weight of less than 5000. This strengthening can also be accomplished by exposing the blends to higher temperatures for shorter times. A level of 1-36 parts by weight silicate filler for each 9 parts by weight polyolefin resin provides composites of particularly useful properties, whereas a weight ratio of the filler to resin of about 2:5 - 5:2 normally provides an optimum balance for silicates as mica flakes and a weight ratio of about 1:10 - 10 being advantageous for silicate as glass fibers.

Preferred silicate is mica, especially mica flakes.

Polyolefin resins suitable for this invention include well known, commercially available materials designed for use in molding (as by injection, compression, etc.) and other melt forming processes (as extrusion, stamping, etc). Of these commercial resins, those made from monomers comprising olefinic hydrocarbons such as ethylene, propylene and butene-t can provide composites with excellent properties as well as economic advantage.

Particularly suitable in this regard are resins comprising polyethylene or polypropylene or copolymers of ethylene and/or propylene as well as blends of any of these. As used herein, polyolefin resin means any of the above identified resins that are typically melt formed and are made from monomers comprising olefinic monomers, particularly monomers that are aliphatic hydrocarbon monomers and preferably predominantly by weight 1-olefins hydrocarbons such as ethylene, propylene, butene-1 and 4-methylpentene-1. Such polyolefin resins preferably comprise a major portion of the resins in the composite (e.g., 60% by weight or more).

Upon melting, the polyolefin resin wets the surfaces of the silicate filler in the blends.

Through some as yet undefined mechanism it is believed that the wetting and bonding is enhanced when the additives of this invention are included in the blends.

Propylene resins are especially benefited by this invention particularly those with intrinsic viscosities of above 1.5 and preferably about 2.0 - 2.6 for processing expedience, although those with higher intrinsic viscosities may also be suitably employed. The propylene resins may comprise propylene homopolymer or propylene copolymer or mixtures thereof, such copolymers normally comprising at least about 75 mole percent propylene and up to 25 mole percent of other monomers such as ethylene and butene-1.

The preferred propylene resins comprise propylene homopolymer or copolymer normally made with stereospecific catalysts. Desirably, these propylene resins are in flake or powder form and pass through a 20 mesh screen, more preferably a 60 mesh screen, and, although currently available propylene resins are substantially retained on a 325 mesh screen, even smaller sizes may be used in this invention. Ethylene resins such as polyethylene homopolymer or ethylene copolymers made with other aliphatic olefin hydrocarbons as propylene, butene-1 and hexene-1 are also particularly desirable.

Silicate fillers are commercially available. Among the commonly used silicate fillers, especially suitable herein, are synthetic glass fibers and natural mica as well as other naturally occurring minerals as talc. These silicate fillers generally comprise silicon, oxygen and one or more metals, e.g., Mg, Al, Na. Fillers having certain shapes as glass flakes, fibers and mica flakes offer advantage in providing increased structural integrity to polyolefin resin composites and such composites can receive particular benefits in accordance with this invention. For example, glass fibers with high length to diameter ratios, e.g. 30:1 or higher as well as flakes with at least such aspect ratios are desirable for highest strength composites. Other silicate fillers include magnesium silicate, calcium silicates, wollastonite, attapulgite, silicate clays as well as others as are disclosed in U.S.

Patent 3,951,680. Silicate fillers are preferred which do not contain forms of asbestos.

It is advantageous that the silicate filler as mica may be free of substantial chemical surface treatment for use in this invention. For one reason, the additives of this invention typically have low cost and can eliminate or reduce the need for more expensive surface treatments as with silane compounds. Moreover, it is desirable that there is minimum interference with the operation of the additive on the silicate surface and the polyolefin resin.

Mica fillers can be generally characterized as being derived from aluminum silicate minerals which can be cleaved into thin sheets. Commercially available fillers which comprise principally muscovite, biotite and/or phlogopite micas (e.g., Suzorite Mica marketed by Marietta Resources International) are preferred with mica fillers comprising principally phlogopite mica being currently more preferred. Mixtures of micas as well as with other silicate fillers can also be employed.

Mica flakes, especially those comprising principally phlogopite mica, having an aspect ratio (mean diameter to thickness) of at least about 30 (more preferably at least about 60 so as to minimize breakage effects during processing) and up to 200 or higher are preferably employed. Mica flakes which are retained on a 100 mesh screen, more preferably on a 60 mesh screen, are normally more desirable, but mica which passes through a 325 mesh can also be employed. Mica flakes which substantially pass through a 20 mesh screen are advantageous for processing expedience. Generally, glass flakes and fibers of such dimensions are especially useful herein. Although various means of preparing highly delaminated mica flakes are employed in the mineral industry, those not employing wet grinding are preferred. Especially preferred are those dry delamination processes in which ore containing in part the various forms of mica is excavated and crushed into lumps for transportation ease. These lumps are further reduced in size by hammer milling in order to free the boxes (or single crystaks of mica) from other mineral impurities.

In such preferred dry processes, the crystals are typically delaminated between counter rotating drums which exert high shearing forces. The degree of delamination, hence the aspect ratio of the resulting mica flakes, is dependent upon the clearances set between the counter rotating drums. The delaminated flakes are then separated from other mineral impurities by vibration and/or air classification techniques with the purified mica still further classified according to particle size via conventional screening processes.

When prepared in this manner the mica surfaces are relatively free from large amounts of adsorbed species (such as moisture from water grinding) which may cause interference to the additives described in this invention.

The additive which strengthens the silicate filler as mica and polyolefin resin adhesion is employed in minor amounts (e.g., 0.05 - 10%, but preferably between about 0.5 - 5%) by weight of the combined weight of silicate filler and polyolefin resin, sufficient to strengthen the composition. Often a sufficient amount of the additive also is less than the amount of silicate filler as measured by weight. For example, resinous chlorinated waxes are normally used at less than about 3% by weight of the total weight of silicate filler and polyolefin resin. ASTM (D-790) Flexural Yield-Strength is a convenient measure of the strengthening of the composite. Other evidence of the strengthening may be seen in, for example, enhanced tensile strength, flexural modulus and heat deflection temperature as well as reduction of mold shrinkage.

The hydrocarbon waxes preferred in this invention have a molecular weight (number average) in a range 500-10,000, (more preferably between 800 and 5,000) and a chlorine content of from about 5 - 80% by weight.

High levels (e.g., about 60 - 80%) by weight chlorine are desirable for chlorinated saturated hydrocarbon waxes such as chlorinated paraffin waxes. Lower levels (e.g., about 5 - 50%) of chlorine by weight are especially suitable, if there is additional polarity (e.g., carboxyl groups) or unsaturation in the chlorinated aliphatic compounds. Lower molecular weight e.g. 250 are preferred when there is a high level of chlorine by weight.

Examples of suitable additives include resinous chlorinated paraffin waxes such as those marketed under the trade marks "Chlorowax" [Diamond Shamrock], "Kloro-chek" [Keil Chemical, a division of Ferro Chemical] and "Chlorez" [Dover Chemical, a division of ICC]. Resinous chlorinated waxes with molecular weights of about 800 - 1200 are preferred, as, for example, Chlorowax 70.

In one preferred method of making composites of this invention, particulate (powder, flake) polyolefin resin, silicate flakes (e.g. mica) or fibers and a powdered additive comprising chlorinated aliphatic compounds are admixed by tumbling (preferably non-intensive) followed by extrusion compounding of the blend with vacuum venting. The extrusion compounder is fitted at the end with a heated pipe which lengthens the time the passing melt is exposed to a high temperature. For propylene resin, silicate filler comprising, for example, phlogopite mica, and resinous chlorinated paraffin waxes, a total time elapsed after melting (i.e., melt residence time) of about 5 - 10 minutes at about 190C 210"C is preferred before melt is cooled. Subsequent heating, as by annealing and drying may also be used to contribute to this residence time. The melt can be shaped thereafter by molding but other fabrication techniques can be employed.

In another preferred method of making, the silicate (e.g., mica) itself is first blended with the additive to preferably provide a coating on the silicate particles (e.g. flakes as mica flakes or fibers). Chlorinated paraffin wax is, for example, desirably melted (at up to about 15% by weight, more preferably up to about 2% by weight of the silicate) onto the silicate preferably at high temperature (e.g. 1500C) but desirably below that temperature which would cause severe decomposition and deterioration of the strengthening effect attributed to the additive. This melt coating is normally conducted during gentle mixing of the silicate particles and the additive to achieve uniformity of the coating and minimize breakage of shaped particles. Preferably, the silicate filler as mica is dried prior to melt coating with the additive. Advantageously, the melt coating can be accomplished in less than one hour, normally less than 15 minutes depending on such factors as equipment mixing, conditions and temperature. The coating of the silicate has the advantage of providing potentially greater uniformity for the blends as compared to mixing the ingredients separately. The coated silicate is further compounded preferably by admixture with the polyolefin resin to form a dry powder blend for further processing.

Temperatures between about 170 - 300"C are typically suitable during such above described preferred compoundings with the polyolefin resin. Higher temperatures with this range, e.g., 220"C or higher, usually require shorter times for optimum development of properties while lower temperature require longer periods. Advantageously, the additives of this invention provide stable subsequently produced mechanical properties at usual melt temperatures for long periods, e.g., 30 minutes or longer. Normally it is desirable to allow a period between about one (1) and 30 minutes at melt temperature, more desirably between about 5 - 15 minutes. Subsequent operations as shaping at melt conditions can contribute to this melt residence time.

After compounding, the melt, preferably having resided for an extended period at melt temperature, can be passed to a cooling zone and thereafter cut (e.g., diced) into particles suitable for shaping processes. Alternatively, the melt may be passed directly into a shaping operation. Shaping, if done by injection molding, is preferably performed at about 3,000 9,000 psi at temperatures of about 190 - 210 C into molds held at about 30 - 70"C.

Other shaping operations such as extrusion, compression or blow molding or stamping and the like may be employed. Further, shaping operations can be used to maintain a time and temperature sufficient to strengthen the composite. Moreover, rods, sheets, tubes and films also can be fabricated and receive the benefits of this invention It is to be understood that blends of this invention may include combinations of fillers such as mica with glass fibers or talc as well as minor amounts of additives (e.g., stabilizers, pigments, lubricants and the like) which are conventionally included during processing of composites. For example, alkaline earth oxides (e.g., MgO, CaO) may be included at up to about 5% by weight of the composite weight and are advantageous to absorb gases resulting from entrapped moisture or decomposition of the additive generated during high temperature compounding or melt forming processes.

The following examples are intended to illustrate this invention and are not intended as limiting thereof as those skilled in the art will appreciate that many modifications of these examples can be made within the scope of this invention. All parts are parts by weight, all temperatures are in degrees centigrade and all tests are ASTM standards as noted, unless specifically indicated otherwise.

Examples 1 to 12 In these examples, composites are formed into standard ASTM specimens from formulations having varying levels and types of polyolefin resin, silicate fillers, and chlorinated hydrocarbon waxes.

The composites are prepared by dry blending (non-intensive mixing) the resin (powder form), silicate filler and additives comprising the chlorinated aliphatic compounds.

Thereafter, the powdery mixture is added to a reciprocating screw injection molding machine (Arburg 200U (Registered trade mark) 42 ton, 2 or. , held at 2000C for times indicated by Table 2 and injected into the mold having a temperature of 30"C. Shot size setting is at 6.3.

The formulation of the composites prepared appear in Table 1.

Properties that are obtained from a first set of composites appear in Table 2. The composites for ASTM testing in this first set are made after first purging the molding machine with 10 shots of the individual formulations spaced one minute apart followed by shots taken at intervals spaced by the time as indicated in Table 2.

TABLE 1 Formulations Formulations in Part by Weight Example Number 1 2 3 4 5 6 7 8 9 10 11 12 Propylene Resin Homopolymer (Hercules Pro Fax 6523-PM) 100.0 70.0 70.0 60.0 50.0 70.0 70.0 --- --- --- 70.0 70.0 Copolymer (Hercules Pro Fax 8523-PM) --- --- --- --- --- --- --- 70.0 --- --- --- -- Polyethylene Resin (USI Microthene MA-778) --- --- --- --- --- --- --- --- 60.0 60.0 --- -- Silicate Filler (particle size) Suzorite5 "GPA" mica 1 (passes through 20 mesh but retained on 60 mesh) --- 30.0 30.0 40.0 50.0 --- 30.0 30.0 40.0 40.0 --- 30.0 Suzorite "-325-5" (passes through 325 mesh) --- --- --- --- --- 30.0 --- --- --- --- --- -- Glass Fiber 2 --- --- --- --- --- --- --- --- --- --- 30.0 -- Additive Chlorowax 70-LP 3 1.0 --- 1.0 1.0 1.0 1.0 --- 1.0 --- 1.0 1.0 -- Polyolefin 310-6 4 --- --- --- --- --- --- 1.0 --- --- --- -- Hexachlorobutadiene --- --- --- --- --- --- --- --- --- --- --- 1.0 1 - Principally phlogopite mica (Marietta International) 2 - Owen Corning Fiber Glass - K-885 " chopped strand 3 - About 70% by weight chlorine (Diamond Shamrock) 4 - About 19% chlorine by weight; viscosity in xylene (50% by weight) 4000 cp at 25 C; Specific gravity 1.54; and softening point (Vicat) of 105 C; marketed by Eastman Chemical 5 - Registered trade mark.

TABLE 2 Example Processing Number Temperature Flexural Yield Strength - psi - ASTM-D790 1* 2* 3* 4* 5* 10* 15* 20* 30* 60* 1 200 C 7,589 7,469 7,264 7,159 6,772 6,356 -- 6,461 6,019 5,838 2 200 C 7,627 7,492 7,495 7,576 7,555 7,303 7,226 7,215 7,225 -3 200 C 7,829 7,884 8,070 8,013 8,257 8,507 9,389 9,486 9,580 9,744 3 285 C 8,971 8,659 7,814 6,560 -- -- -- -- -- -4 200 C 7,488 7,438 7,629 8,246 8,966 9,600 -- 10,166 9,735 9,519 5 200 C 7,952 8,523 9,596 10,275 10,832 11,131 -- 11,079 10,331 10,507 6 200 C 8,584 8,769 9,300 9,749 9,781 10,048 10,062 9,978 10,028 10,044 7 200 C 9,429 8,941 9,153 8,725 8,937 8,625 8,660 -- 8,419 8,373 8 200 C 5,116 5,099 5,030 5,513 6,012 6,309 6,595 6,659 6,495 6,413 9 200 C 3,788 3,634 3,802 3,879 3,802 3,821 3,736 3,747 3,886 -10 200 C 6,071 6,171 6,250 6,261 6,331 6,193 6,082 6,029 6,177 -11 200 C 10,537 10,506 11,459 12,151 13,609 14,984 -- 13,957 16,082 18,622 12 200 C 6,279 6,316 6,378 6,747 7,128 -- 6,775 -- -- - *Time between successive shots (minutes) In Table 3, the effect of the additive is seen by comparison of properties of composites made with and without the additive of this invention The formulation used in making composites A and B in Table 3, below, corresponds to formulation 4 of Table 1, except that the formulation of B does not include the additive of this invention. Chlorowax(R)70-LP is used as the additive in A. The ASTM specimens having properties as set forth in Table 3 are made as those above except that the molding cycle is set for 10 minutes and the first ten specimens are discarded to approximate a steady state condition. Sufficient specimens are thereafter collected to perform the ASTM tests in Table 3.

TABLE 3 - PHYSICAL PROPERTIES Composite A B With Without Physical Property Units Additive Additive Tensile Strength psi 5,600 4,100 ASTM-D638 Flexural Strength psi 10,250 7,200 ASTM-D790 Flexural Modulus psi 1,127,000 850,000 ASTM-D790 Izod Impact ft-lbs 1.25 1.30 ASTM-D256 Heat Defl. Temp "F ASTM-D648 @66 psi 301 266 @264 psi 272 210 Mold Shrinkage in/in ASTM-D955 length .002 .010 width .010 .007 thickness .020 .023 Example 13 In this example, composites are made from formulations containing 30 parts by weight Hercules Pro-Fax 6523-PM propylene resin and 70 parts by weight muscovite mica flakes (K-100 English Mica Co.) with and without 1 part by weight Chlorowax 70-LP powder. The procedure of Example 1 is followed and ASTM specimens are obtained at the time intervals indicated by Table 2.

The composites made with the additive of this invention show an ASTM-D790 Flexural Yield Strength that is higher than composites made without the additive.

Examples 14 to 19 In these examples, the formulations of Examples 3-8 are modified by the inclusion of 1 additional part by weight of the individual chlorinated aliphatic compounds. Composites are made and tested by a method similar to that described in Example 1 and likewise show the desirable strengths attained by inclusion of the additive of this invention as compared to composites without the additive.

Example 20 The formulation of Example 4, (Table 1) is compounded in an extrusion compounder (2 inch Transfermix, manufactured by Sterling Extruder Corp.) having a heated pipe extension (length 50 inches, inner diameter 2.25 inches) fitted at the end. The compounder is operated so that the passing melt has a residence of about 9 minutes at 2000C during extrusion and passage through the heated pipe. The melt is cooled and then diced into pellets. The pellets are fed into an injection molder and molded into ASTM specimens.

These specimens are tested and show advantageous properties as compared to ones which do not have the additive of this invention and which are made in the same manner.

Example 21 The formulation of Example 4 (Table 1) is modified by the addition of 5 parts by weight of commercial glass fiber (Owens-Corning, Fiberglass 885, 1/4 inch chopped strand, aspect ratio of about 500 to 1). Processing is done as in Example 1 above. Higher Yield Strength values (ASTM D-790) are seen in these composites which are molded into ASTM speciment as compared to composites made in the same manner for like periods but without the additive of this invention. At 20 minutes as in Table 2, the composite of this invention has a Flexural Yield Strength of 11,000 whereas the one without additive has a value of 8,000.

Example 22 Two parts by weight of a resinous chlorinated paraffin (Chlorez 700 of Dover Chemical) is combined by 98 parts by weight Suzorite GPA mica (Marietta Resources) by gently mixing in a V-shaped blender at room temperature for about 3 minutes. Thereafter, this admixture is heated up to about 1500C with gentle mixing continued whereupon a coating of the surface of the mica occurs and the brassy color of the mica begins to turn to a dark red gold. Small portions of the mica mixture are taken to see if the coating is complete by seeing if the surface is still wetted with water.

Mica coated in this manner with additive is used in place of the mica and additive of Example 20 and compared with a formulation containing no additive using the conditions of Example 20. Improved properties are seen in composites made in accordance with this invention Examples 23 and 24 One part by weight of Chlorowax 70 (Diamond Shamrock) is used to coat 40 parts by weight of mica (Suzorite GPA, Marietta Resources) in two ways. In Example 23, the mica is preheated to 200"C for several minutes prior to addition of the Chlorowax at that temperature. In Example 24, the Chlorowax 70 is added at room temperature prior to heating at 200"C. The coated mica samples are each allowed to cool, then separately blended with 60 parts by weight of Hercules Profax 6501 PM polypropylene and injected molded at 2000 with an extended molding cycle. The following properties are obtained with ASTM testing: Example 23 Example 24 Flexural 8500 psi (mean of 5) 7778 (mean of 5) Strength 280 psi (std. deviation) 395 (std. deviation) Flexural 1,013,346 psi (mean of 5) 1,087,952 (mean of 5) Modulus 61,612 psi (std. devia- 57,271 (std. devia tion 57,721) tion) Example 25 The procedure of example 22 is followed using glass flakes (aspect ratio greater than 30) rather than mica. Composites formed show desirable properties.

Example 26 The procedure of example 1 is repeated using specially prepared "nascent" glass fibers having no surface treatment with silane coupling agents. Composites are made according to procedure and formulating example 11. Composites made with the additive show improvement in mechanical strength over similar composites made without the additive of this invention.

As previously mentioned, a preferred compounding technique in accordance with this invention utilizes an extruder that provides extended periods at melt temperatures for development of optimum mechanical properties of the composites. Basically, this may be accomplished, if desired, by including a melt holding chamber between the gate and the die (or nozzle) of an extruder or the extruder portion of a more complex (i.e. injection, blow molding, foam, sheet, etc.) system. Inclusion of this melt holding chamber enables desired production rates to be maintained. The actual dimensions, of course, of the chamber will be determined by the relative output rate desired as well as physical space available. In certain specialized instances, however, usual equipment such as large shot size injection molding devices may be used to mold small parts whereby the melt exists for longer than usual times so that optimum properties develop.

Example 27 The procedure of example 22 is repeated using talc (Beaver White 200 - United Sierra) in place of mica. The coated talc, however, does not exhibit the color change as does mica unless the coating process is conducted at temperatures exceeding the onset of thermal decomposition of the chlorinated hydrocarbon coupling agent.

Increased Heat Deflection Temperature (ASTM-D648) is noted in composites containing 40 parts of the above described coated talc and 60 parts polypropylene homopolymer when the composite is prepared with the compounding techniques in accordance with example 20.

Example 28 Fiberized blast furnace slag (Mineral Fibers - Jim Walter Corporation), a silicate fiber filler typically containing over 40% SiO2 is washed with xylene to remove the normally present anti-dusting oils and is subsequently dried. Dry powdery blends are formed of a composition of 40 parts mineral fiber, 60 parts polypropylene resin (Profax 6523-PM Hercules, Inc.) and 2 parts of chlorinated hydrocarbon additive (Chlorex 700 - Dover Chemical).

When these powdery blends are directly injection molded in accordance with example 1 as to increase the melt residence time to 10 minutes, the resultant molded parts exhibit improved flexural strength at yield when tested in accordance with ASTM-D790 (Flexural Properties of Plastics).

Claims (34)

WHAT WE CLAIM IS:

1. A composition comprising a silicate filler, a polyolefin resin, and a minor amount by weight, based on the combined weight of the silicate filler and polyolefin resin, of an additive which comprises one or more chlorinated hydrocarbon waxes with a molecular weight of from 250 to 10,000 and containing from 5 to 80% chlorine by weight.

2. A composition according to Claim 1, wherein the filler comprises glass fiber or flakes.

3. A composition according to Claim 1, wherein the silicate filler comprises. mica.

4. A composition according to any one of Claims 1 to 3, wherein the polyolefin resin comprises polyethylene homopolymer or copolymer or mixtures thereof.

5. A composition according to any one of Claims 1 to 3 wherein the polyolefin resin comprises polypropylene nomopolymer or copolymer of mixtures thereof.

6. A composition according to any one of Claims 1 to 5, wherein the filler comprises biotite, phlogopite or muscovite mica or a mixture thereof.

7. A composition according to Claim 6, wherein the filler comprises phlogopite mica having an aspect ratio of from 30 to 200.

8. A composition according to any one of Claims 1 to 7, wherein the molecular weight of the additive is from 800 to 5,000.

9. A composition according to any one of Claims 1 to 7, wherein the additive comprises a resinous chlorinated paraffin wax having from 60 to 80% chlorine by weight.

10. A composite according to any one of Claims 1 to 9, wherein the additive comprises from 0.2 to 3% by weight of the combined weight of the filler and resin.

11. A composition according to any one of Claims 1 to 10, wherein the weight ratio of the filler to resin is from 5:2 to 2:5.

12. A composition material according to Claim 1 wherein the filler comprises mica and the said additive has a molecular weight of from 500 to 10,000.

13. A composition substantially as described in any one of Examples 3 to 6, 8, 10, 11, and 13 to 28.

14. A composition substantially as described in any one of Examples 3 to 6, 8, 10 and 13 to 21.

15. A process for making a mouldable material comprising the steps of (a) melting a blend comprising silicate filler, polyolefin resin, and a minor amount by weight of the combined weight of the silicate filler and resin of an additive which comprises one or more chlorinated hydrocarbon waxes with a molecular weight in the range of from 250 to 10,000 and containing from 5 to 80% chlorine by weight; and (b) maintaining the blend for a time and at a temperature sufficient to improve the strength of the composition.

16. A process according to Claim 15, wherein the silicate filler comprises mica.

17. A process according to Claim 15 or Claim 16 wherein the polyolefin resin comprises polyethylene.

18. A process according to Claim 15 or Claim 16 wherein the polyolefin resin comprises propylene homopolymer or copolymer or mixtures thereof.

19. A process according to any one of Claims 15 to 18 wherein the silicate filler comprises glass fibers or flakes.

20. A process according to any one of Claims 15 to 29 wherein the filler comprises biotite, phlogopite or muscovita mica or a mixture thereof.

21. A process according to any one of Claims 15 to 20, wherein the molecular weight of the additive is in a range of from 800 to 5,000.

22. A process according to any one of Claims 15 to 21, wherein the additive comprises resinous chlorinated paraffin wax having from 60 to 80% chlorine by weight.

23. A process according to any one of Claims 15 to 22 wherein the additive comprises from 0.2 to 3% by weight of the combined weight of the filler and resin.

24. A process according to any one of Claims 15 to 23 wherein the weight ratio of the filler to resin is from 5:2 - 2:5.

25. A process according to any one of Claims 15 to 24 wherein the filler and additive are combined prior to melting the blend.

26. A process according to any one of Claims 15 to 25 wherein the blend is maintained at a temperature of at least 1700C for at least five minutes.

27. A process according to Claim 15 wherein the filler comprises mica and the said aliphatic compounds have a molecular weight of from 500 to 10,000.

28. A process for making a mouldable material substantially as described in any one of Examples 3 to 6, 8, 10, 11 and 13 to 28.

29. A process for making a mouldable material substantially as described in any one of Examples 3 to 6, 8, 10 and 13 to 21.

30. A mouldable material found by a process according to any one of Claims 15 to 29.

31. A composition according to any one of Claims 1 to 14 in the form of a powder blend of the polyolefin, filler and additive.

32. A filler material suitable for improving the strength of polyolefin resin composites, which comprises particles of a silicate filler blended with an additive comprising one or more chlorinated hydrocarbon waxes with a molecular weight of from 250 to 10,000 and containing from 5 to 80% chlorine by weight.

33. A filler according to Claim 32, wherein the silicate and aliphatic compound are as defined in any one of Claims 2 to 14.

34. A filler material according to Claim 32 wherein the silicate filler particles are coated with the additive.