GB2031910A

GB2031910A - Thermoplastic composites

Info

Publication number: GB2031910A
Application number: GB7931289A
Authority: GB
Original assignee: NL Industries Inc
Current assignee: NL Industries Inc
Priority date: 1978-09-11
Filing date: 1979-09-10
Publication date: 1980-04-30
Also published as: NL7906769A; SE7907492L; GB2031910B; AU5042679A; IT1122930B; BE878559A; IT7925413A0; CA1126427A; DE2936510A1; JPS5538874A; FR2435500A1

Abstract

Filled thermoplastic resin composites are provided containing a novel coupling agent selected from mono-, di- and tri-long chain fatty acid esters of C1 to C36 mono and polyhydric alcohols. The coupling agents are particularly effective agents for calcium carbonate filled thermoplastic resins for which previously used couplings agents, such as organosilanes, proved ineffective.

Description

SPECIFICATION Thermoplastic composites This invention is concerned with coupling agents for filled plastics particularly calcium carbonate filled plastics.

In view of the recent shortages of petroleum feed stocks necessary to manufacture such polymers as polyethylene, PVC, polypropylene and other polyolefins and the expectancy that these shortages will continue, there has arisen a need to incorporate larger volumes of inexpensive filler products into these polymers. These fillers function as extenders and reinforcing aids to improve the mechanical properties of the polymer in which they are incorporated such as tensile impact strength, ductility and Gardner impact strength. It is expected that the volume of theremoplastic polymers requiring fillers will continue to grow at increasing rates each year.

Coupling agents or adhesion promoters are often used in filled plastic composites to aid in the incorporation of filler into the polymer and to form an adhesive bond between filler and polymer. These coupling agents become more essential as higher loadings of filler are incorporated into the plastics. By virtue of such coupling agents, useful theremoplastic composites containing about 70% filler can be processed using conventional extrusion and injection molding equipment.

Heretofore, organo-silanes have been the most widely used coupling agents for filled plastic composites.

These organo-silane coupling agents have demonstrated a high degree of success in bonding numerous polymer resins filled with silica, metal silicates or metal oxides. They have not been as effective, however, in other systems, such as with calcium carbonate fillers which are used extensively in many resins.

Organo-titanates function to some degree as bonding agents for calcium carbonate filler polymers and are therefore useful as coupling agents.

The present invention, on the other hand, provides non-titanate, non-silane coupling agents which bond theremoplastic polymers to a variety of inorganic mineral fillers. Thermoplastic resin filler composites containing these agents exhibit improvements in physical properties, processability and thermal stability.

The agents of this invention perform as well or better than the organo-titanates as coupling agents for calcium carbonate filled polymers but are distinctly superior to the titanates in terms of cost.

The coupling agents of this invention comprise mono-,di-, and tri-, long chain fatty acid esters of C1 to C36 mono and polyhydric alcohols and preferably C1 to C4 mono and polyhydric alcohols. Preferably, coupling agents from this class will be selected from the group consisting of the mono-di-,and tri-esters of hydroxy fatty acids or acetyl derivatives thereof.

The present coupling agents can be prepared by esterifying the fatty acids with C1 to C36 alcohols and polyols such as methanol, propanol, butanol, ethylene glycol, propylene glycol, pentaerythritol, glycerol, decanol, dodecanol, tetrade-canol, pentadecanol, hexadecanol, octadecanol, eicosanol, docosanol and tetratriacontanol as well known in the art to form mono-,di- and tri-esters of fatty acids.

Typical long chain hydroxy fatty acid esters or acetyl derivatives thereof of this invention are methyl ricinoleate methyl acetyl ricinoleate, ethyl acetyl ricinoleate, ethyl ricinoleate, butyl ricinoleate, buytyl acetyl ricinoleate, glycery tri (ricinoleate), glyceryl tri (acetyl ricinoleate) methyl hydroxy stearate, methyl acetyl stearate, ethyl hydroxy stearate, ethyl acetyl stearate, butyl hydroxy stearate, butyl acetyl stearate, glyceryl tri hydroxy (stearate), and glyceryl tri (acetyl stearate).

The hydroxy fatty acids of acetyl derivatives thereof may have saturated or unsaturated fatty acid chains and contain 8 to 22 carbon atoms, and preferably 18 carbon atoms. Exemplary compounds are hydroxy stearic acid and ricinoleic acid (i.e. hydroxy oleic acid) and acetyl derivatives thereof.

The preferred coupling agents of this invention may be represented by the formula: Formula I:

wherein R1 is a hydroxyl group or acetyl group; R2 is -CH=CH-, or -CH2-CH2-; R3 is a mono, di- or tri- ester group containing from 1 to 36 carbon atoms.

A preferred compound is an ester of acetyl ricinoleic acid, i.e. 12-acetyl-9-octadecenoic acid, represented by the formula wherein R3 represents the ester group: Formula ll:

Another preferred compound is an ester of acetyl stearic acid, i.e. 1 2-acetyl-9-octadecanoic acid, represented by the formula wherein R3 represents the ester group: Formula Ill:

The preferred hydroxy fatty acid esters and acetyl derivatives thereof of this invention are lower alkyl mono ricinoleates and hydroxy stearates wherein the alkyl group contains from 1 to 36 carbon atoms.While all of the compounds of this invention act as excellent bonding agents between the resin and inorganic filler, the methyl acetyl ricinoleate imparts superior reinforcing properties, such as tensile impact strength and ductility to the filled resin composites in which it is incorporated.

The amount of hydroxy fatty acid ester or acetyl derivative thereof incorporated in the filled thermoplastic composite can vary over wide ranges. It is typically employed in amounts of about 0.5 to about 7.5% by weight of the filler component, and preferably about 0.5 to about 5% by weight of the filler component.

It has been found that by virtue of the coupling agents used in this invention, up to 80% by weight, preferably 5% to 75% and most preferably 10% to 70% of inorganic filler can be incorporated into the resin to form a composite based on the weight of total composite.

As previously mentioned, the coupling agents used in this invention can be used with a variety of inorganic mineral fillers including silicas, metal silicates, metal oxides, hydrated aluminum oxides and antimony trioxide, the latter of which are used as flame-retardant additives for polyolefins and combinations thereof.The theremoplastic resins in which the coupling agents of this invention may be used to bond fillers thereto include the the polymeric amides, such as nylon and products of polymerization of organic monomers containing one or more unsaturated double bonds such as ethylene, propylene, styrene, acrylobutadiene styrene, methacrylic acid, vinyl acetate, vinyl chloride and mixtures thereof.

The coupling agents used in this invention are particularly useful in calcium carbonate filled thermoplastic resin composites such as calcium carbonate filled high density polyethylene resins, homopolymer polypropylene resins and polyvinyl chloride resins. The calcium carbonate fillers can be either coated or uncoated and can vary in particle size distribution from 0.06 to 6.0 microns. Moreover, resin filler composites containing the coupling agents can be procesed at temperatures of about 335 F. (177"C) without change in color which indicates a heat stabilizing effect on the composite.

The long chain fatty acid esters and acetyl derivatives thereof used in this invention can be incorporated with the resin and filler by a variety of conventional methods. For example, the resin may first be fluxed on a 2 roll calender at temperatures sufficient to fuse the resin. Next, the coupler may be blended by mixing with the resin followed by blending the filler in the resin-coupler mix. In another method, the filler and coupling agent may be blended in a high speed mixer to coat the coupling agent on the filler. The coated filler is then milled with the resin on a 2 roll calender. In still another method, the coupling agent is first dissolved in toluene followed by slurrying the solution with filler to again coat the filler. The slurry is then dried and fluxed with the resin on a 2 roll calender.The so-formed composite may be compounded and processed by conventional techniques to fabricate a large variety of self-supporting or laminar piastic forms.

The bonding action of the hydroxy fatty acid esters or acetyl derivatives thereof permits the plastics manufacturer to incorporate increasingly higher levels of low cost inorganic mineral fillers without sacrificing certain highly desirable properties such as impact strength, melt flow and thermal stability. The fatty acid esters of this invention permit bonding of fillers other than the silicas, metal silicates and metal oxides, particularly calcium carbonate. Calcium carbonate and other-non-silicate, non-oxide minerals have until now, resisted being bonded to organic polymers by means of conventional coupling agents such as the organo-silanes.

The thermoplastic composite may be compounded and processed by conventional techniques such as injection molding, and extrusion. Injection molded calcium carbonate filled composites prepared using couplers of this invention give improved reinforcement and melt flow properties relative to commercial injection molded resin composites filled with a metal silicate such as talc.

The foilowing examples are given to illustrate the invention, but are not deemed to be limiting thereof. All percentages given are based upon weight unless otherwise indicated.

Examples 1 to 6 These examples illustrate the effect of the alkyl acetyl ricinoleate coupling agents used in this invention in improving the reinforcing characteristics of high density polyethylene (HDPE) filled with 30% by weight of an uncoated calcium carbonate product having a mean particle size distribution of 2.5 microns. The coupling agents used were methyl acetyl ricinoleate, butyl acetyl ricinoleate, glyceryl tri-(acetyl) ricinoleate) and glyceryl tri (acetoxystearate).

A 3% coating of each coupling agent, based on the filler weight was accomplished by premixing 1.89. of coupler with 609. of calcium carbonate in a Ronson blender for 1 minute at250"R (121"C). The resulting coated calcium carbonate powders were processed with 1409. of HDPE for 8 minutes using a 2-roll calender set at 275"F. (135"C). The so-formed stocks were removed and compression molded for 5 minutes at 325"F.

(163"C) to form 40 mil. (1 mm) slabs which were then tested for tensile impact strength using a Plastics Impact Tester (model TM 52004, Testing Machines, Inc.). The results obtained comprised an average of six test specimens on each example; 3 cut in a direction parallel to milling and 3 cut at 90 to the direction of milling.

As controls, a HDPE sample containing no filler and coupler, and a sample containing calcium carbonate filler and no coupler were tested. A sample containing calcium carbonate filler and an organo titanate coupler, isopropyl triisostearic titanate was also tested. The results are given in Table 1 below:: TABLE 1 Example Filler Coupling Agent Tensile Impact Ductility STR.(ft-lbs/in2) (milliseconds) 1 None None 144(34.8)* 2.1 2 CaCO3 None 74 (17.9) 0.9 3 CaCO3 Methyl acetyl ricinoleate 139 (33.6) 2.5 4 CaCO3 Butyl acetyl ricinoleate 92 (22.2) 1.3 5A CaCO3 Glyceryl tri (acetyl ricinoleate 118(28.5) 1.9 5B CaCO3 Glyceryl tri (acetoxystearate) 103 (24.9) 1.7 6 CaCO3 Isopropyl triisostearic titanate 118(28.5) 2.1 * Figures in brackets are in Newton metres per sq.c.m (N.M.cm-2) As Table 1 shows, a significant improvement in the reinforcing properties of calcium carbonate occurred when coated with alkyl acetyl ricinoleates of this invention (compare Ex. 2 with Examples 3,4 and 5).The methyl acetyl ricinoleate, glyceryl tri (acetyl ricinoleate) and glyceryl tri (acetoxystearate) coated calcium carbonate performed as good or better than the organo titanate.

Examples 7 to 17 These examples illustrate the various conventional compounding techniques can be used to incorporate the alkyl acetyl ricinoleates of this invention in a thermoplastic polymeric material to yield a composite having excellent reinforcement properties.

In each example a filled composite containing 30% calcium carbonate and 70% HDPE was prepared.

Example 8, containing only 30% calcium carbonate without coupler was used as a control.

Two alkyl acetyl ricinoleates of this invention, methylacetyl ricinoleate and butyl acetyl ricinoleate were incorporated in the composite by different conventional methods and the resulting milled stocks were compression molded for 5 minutes at 325"F. (163"C) to form 0.040 inch (1 mm) plaques. Specimens were cut from each plaque and used for tensile impact strength and ductility tests. An organo titanate coupler, isopropyl triisostearic titanate, was also incorporated into the composition for each method employed and tested.

In the first series of examples (8-11) the HDPE was fluxed on a 2 roll calendar at 275"F. (1350C) and after fusion took place (2 min.), the coupling agents were added and mixed for 3 minutes. The calcium carbonate filler was slowly added to the HDPE-coupling agent mixture and the resulting composite mixed for a total of 10 minutes. A composite containing no coupler was prepared as a control (Ex. 8).

In Examples 12-14 the calcium carbonate was first combined with the coupling agents in a high speed blender. The so-formed coated fillers were incorporated into the HDPE on a 2 roll calender and milled for 10 minutes.

In Examples 15-17 the coupling agents were first dissolved in toluene and this solution was slurried with calcium carbonate to form a 3% coating over the calcium carbonate. The slurry was dried at 120"C. for 45 minutes and the coated calcium carbonate fluxed with the HDPE for 10 minutes at 275"F. (135"C) on a 2 roll calender.

Table 2 below summarizes the results.

TABLE 2 Method of Coupler Tensileimpact str. Ductility Ex Filler Incorporation (3% of filler wt) (ft-lbs/in2) mS.

7 None None 141 (34.1)* 1.8 8 CaCO3 Components None 62 (15) 0.7 Hand Blended 9 CaCO3 On 2 rolls Isopropyl Triiso- 140 (33.8) 1.8 Calender stearic Titanate 10 CaCO3 Methyl acetyl 133 (32.1) 1.8 Ricinoleate 11 CaCO3 Butyl Acetyl 111 (26.8) 1.7 Ricinoleate 12 CaCO3 Isopropyl Triiso- 112 (27) 1.7 stearic Titanate Calcium 13 CaCO3 Carbonate Methyl Acetyl 121 (29.2) 1.7 Preheated Ricinoleate In Blender 14 CaCO3 Butyl Acetyl 110 (26.6) 1.7 Ricinoleate 15 CaCO3 Isopropyl Triiso- 127 (30.7) 2.0 Couplers stearic Titanate Deposited 16 CaCO3 on Calcium Methyl Acetyl 132(31.9) 2.2 Carbonate Ricinoleate Via Toluene 17 CaCO3 Butyl Acetyl 94 (22.7) 2.4 Ricinoleate *Figures in brackets are in Newton metres per sq. cm.

As Table 2 shows, irrespective of the method of coating the filler and incorporating the coated filler in the resin, excellent reinforcing properties of the HDPE-filler composite result. Moveover, methyl acetyl ricinoleate - coated fillers inparted more improved reinforcing properties to the composite than the organo titanate coated fillers, except for the method used in Examples 8-11 in which the ricinoleate was comparable to the titanate.

Examples 18 to 30 These examples illustrate the effect on the reinforcement properties of a high density polyethylene resin containing calcium carbonate filler coated with various amounts of methyl acetyl ricinoleate.

In these examples, methyl acetyl ricinoleate was blended with calcium carbonate having an average particle size of 2.5 microns in a high speed blender to form calcium carbonate coated with from about 0.5 to 7.5% by weight of ricinoleate. The coated filler was incorporated with HDPE using a 2 roll calender to form a 30% calcium carbonate composite. The composites were fluxed for 10 minutes at 275 F. (135 C) sheeted off and compression molded to form 0.040 inch (1 m in) plaques which were tested for tensile impact strength and ductility. A HDPE sample containing no filler (Ex. 18) and a HDPE sample containing 30% uncoated calcium carbonate (Ex. 19) were also tested as controls.

The results are given in Table 3 below: TABLE 3 Example FILLER Methyl acetyl ricinoleate tensile impact Ductility (wt. % of filler wt.) (ft-lbs/in2) (milliseconds) 18 None 0 123 (27.7) 1.7 19 CaCO3 0 73 (17.6) 0.7 20 CaCO3 0.5 70(16.9) 0.7 21 CaCO3 1.0 83 (20) 0.9 22 CaCO3 2.0 104(25.1) 1.1 23 CaCO3 2.5 117(28.3) 1.5 24 CaCO3 3.0 116(28) 1.7 25 CaCO3 3.5 129 (31.2) 1.7 26 CaCO3 4.0 125(30.2) 1.9 27 CaCO3 4.5 111(26.8) 1.6 28 CaCO3 5.0 108 (26.1) 2.1 29 CaCO3 6.0 107 (25.8) 1.0 30 CaCO3 7.5 88 (21.3) 1.2 * Figures in brackets in N.m.cm-7.

As the table shows, improvement in tensile impact strength and ductility over the uncoated filler occurred at about 1.0% methyl acetyl ricinoleate. Optimum reinforcement occurred in composites formulated with calcium carbonate which had a 3.5-4.0% coating of methyl acetyl ricinoleate. After about 4.0% coating levels, reinforcing properties of the composite were gradually reduced but still better than with uncoated filler.

Examples 31 to 40 These examples illustrate the improvement of reinforcing properties of an HDPE composite containing coated or uncoated calcium carbonate, by treating the calcium carbonate with an alkyl acetyl ricinoleate of this invention, methyl acetyl ricinoleate.

Avariety of commercial coated and uncoated calcium carbonate products having a mean particle size distribution ranging from 0.06 microns to 6.0 microns were treated with methyl acetyl ricinoleate using a high speed blender. The treated products were fluxed with HDPE for 10 minutes at 275"F. (135"C) on a 2 roll calender to form a composite containing 70% HDPE and 30% filler. For comparison, a series of coated and uncoated calcium carbonate fillers were fluxed with HDPE without prior treatment with a coupler. All stocks were compression molded 5 minutes at 325"F. (163"C) into .040 inch (1 mm) plaques and tested for tensile impact properties.

A HDPE sample containing no filler and coupler were tested as a control.

The results are given in Table 4 below: TABLE 4 CaCO3 Example Mean Particle Tensile Impact Strength, (ft-lbs/in2) Size, (microns) - No Coupler 3% Methyl Acetyl Ricinoleate 31 No Filler 123(29.7)* 130 (31.4)* Uncoated CaCO3 32 6.0 62(15) 67(16.2) 33 2.5 64(15.5) 107(25.8) 34 2.5 81(19.6) 114(27.5) 35 0.7 61 (14.7) 96 (23;1) 36 0.06 49(11.8) 64(15.5) Coated CaC03 37 2.5 77(18.6 93(22.5) 38 2.5 100(24.1) 105(25.4) 39 0.5 100(24.1) 140(33.8) 40 0.06 44(10.6) 53(12.8) * Figures in brackets in N.M.Cm-2 As Table 4 shows, in each case, whether the calcium carbonate filler was coated or uncoated, significant improvement in the reinforcing properties of the HDPE composite was achieved using treatments of methyl acetyl ricinoleate.

Examples 41 to 54 These examples show that an alkyl acetyl ricinoleate of this invention methyl acetyl ricinoleate, can be used to improve the reinforcement properties af polypropylene homopolymer (PP)/calcium carbonate composite.

Methyl acetyl ricinoleate was used to provide a 3% coating over a series of uncoated calcium carbonate products or an additional 3% coating over coated calcium carbonate products using a high speed blender.

For comparisons, the uncoated and coated calcium carbonate products alone were also employed for incorporation with PP.

Composites of PP and 30%, 50% and 70% calcium carbonate were prepared by first fluxing the PP for 2 minutes on a roll calender at 335 F. (168 C) The calcium carbonate products were subsequently added and the total composite mixed an additional 8 minutes. The resulting stocks were compression molded for 5 minutes at 350"F. (177 C) to form 0.040 in.(1 mm.) plaques which were then used to determine tensile impact strength, ductility and Gardner impact strength at 75 F.(23.9 C).

The results are given in Stable 5 below: Methyl acetyl Tensile impact test Gardner impact Example CaCO3 Ricinoleate % Impact str. Ductility Test* % (based on filler wt.) (ft-lbs/in2) millisecs.) ft-lbs) Uncoated CaCO3 (2.8 microns) 41 0 0 129 (31.2)# 1.3 2.4 (3.25)** 42 30 0 83 (20) 1.0 3.0 (4.07) 43 30 3 144 (34.8) 1.3 3.3 (4.47) 44 50 0 68 (16.4) 0.8 1.5 (2.03) 45 50 3 125 (30.2) 1.8 2.5 (3.39) 46 70 0 34 (8.2) 0.1 0.1 (0.14) 47 70 3 73 (17.6) 0.8 1.1 (1.49) Coated CaCO3 (0.5 microns) 48 0 0 129 (31.1) 1.3 2.4 (3.25) 49 30 0 144 (34.8) 2.0 3.5 (4.74) 50 30 3 168 (40.6) 2.6 4.7 (6.37) 51 50 0 115 (27.8) 1.6 2.4 (3.25) 52 50 3 135 (32.6) 2.2 3.6 (4.88) 53 70 0 50 (12.1) 0.6 0.8 (1.08) 54 70 3 85 (20.5) 1.3 1.3 (1.76) *employed a 4 lb falling weight which was gradually raised to varying heights until rupture of the test specimens occurred, #Figures in brackets in N.M.cm.-2 **Figures in brackets in Newton metres (N.m).

As Table 5 shows, at each level of calcium carbonate in the composite, whether or not such carbonate filler was coated or uncoated, improved tensile impact strength, ductility, and Gardner impact strength resulted when the fillers were treated with methyl acetyl ricinoleate according to this invention.

Examples 55 to 58 These examples illustrate that methyl acetyl ricinoleate also acts as a stabilizer additive for thermoplastic resins to prevent discoloration of the filled resin during thermal processing.

In these examples, PP resin composites were prepared with 30% calcium carbonate alone, 30% methyl acetyl ricinoleate-coated calcium carbonate and 30% isopropyl triisostearic titanate-coated calcium carbonate. As a control, a PP resin containing no filler or coupling agent was also tested. All samples were heated to 335"F.(1680C) for 10 minutes and the color observed.

Table 6 below summarizes the results: TABLE 6 CaC03 Example (2.8 microns) Coupler type Composite color 10 mins.&commat; 335'F.

55 none None Clear 56 30 None Off-White 57 30 Methyl Acetyl Off-White Rincinoleate 58 30 Isopropyl Triiso- Tan-Orange stearyl Titanate As Table 6 shows the resin composite containing methyl acetyl ricinoleate coated calcium carbonate did not undergo any color change reiative to the resin composite containing no coupling agent.

Examples 59 to 71 These examples illustrate that calcium carbonate treated with 3% methyl acetyl ricinoleate (MAR) can be compounded at up to 50% loading with homopolymer (PP) resin, and the resulting composite injection molded using conventional molding techniques.

A series of PP resin composite containing 30% and 50% uncoated and coated calcium carbonate were prepared. Similarly another series of PP resin composites were prepared containing the above amounts of coated and uncoated calcium carbonate treated with 3% of MAR. PP resin containing no filler or coupler was selected as a control Far each example, the tensile impact at 75"F. (23.9"C) and Gardner impact (75"F (23.9"C and O"F (17.8"C) were determined melt flow characteristics were determined using procedures outlined in ASTM D-1 238, "Measuring Flow Rate of Thermoplastics by Extrusion Plastometer" with a pressure mass of 2160 grams at 246"C.

Comparisons were also made against commercial injection molded PP resins containing talc as mineral filler and also against a high impact unfilled copolymer PP resin.

Table 7 summarizes the results: TABLE 7 CaCO3 MAR Tensile impact Gardner impact Flow rate Ex % % Strength Ductility (Ft-lbs 246 C-2160(gms (ft.lbs/in) millisecs) 75 (23.9 C) 0 F(-17.8 C) (gms/10 mins) Uncoated CaCO3 (2.8 microns) 59 0 0 191 (46.1)* 1.7 0.3 0.2 1.1 (0.41)058 (0.27(# 60 30 0 146 (35.3) 1.7 3.9 1.4 0.2 (5.29 (1.9) 61 30 3 146 (35.3) 1.9 6.3 2.1 1.0 (8.54) (2.85) 62 50 0 123 (29.7) 1.9 6.5 1.5 0.4 (8.81) (2.03) 63 50 3 149 (40) 2.4 6.7 2.8 0.8 (9.08 (3.8) Coated CaCO3 (0.5 microns) 64 0 0 191 (46.1) 1.7 0.3 0.2 1.1 (0.41) (0.27) 65 30 0 181 (43.7) 2.5 7.2 2.2 0.8 (9.76 (2.98) 66 30 3 182 (44) 2.3 8.9 2.8 1.0 (12.07) (3.8) 67 50 0 150 (36.2) 2.4 7.8 4.1 1.2 (10.58) (5.56) 68 50 3 162 2.7 8.1 5.8 1.4 (10.98) (7.86) Commercial injection molding PP composites 69 Copolymer PP 21652.2) 2.8 7.8 4.0 0.8 (10.58) (5.42) 70 PP/Talc(60/40) 65 (15.7) 0.5 0.3 0.4 0.5 (0.41) (0.27) 71 PP/Talc(80/20) 97 (23.4) 1.2 3.2 0.8 0.3 (4.34) (1.08) * Figures in brackets in N.m.cm.-2 #Figures in brackets in N.m.

As the Table shows, the treatment of CaCO3 with methyl acetyl ricinoleate produces injection molded PP/CaCO3 composites with improved reinforcement and melt flow properties over untreated PP/CaCO3 composites and over commercial injection molded PP composite.

Examples 72 to 74 These examples illustrate the improvements of reinforcing properties of polypropylene resins filled with antimony trioxide wherein the antimony trioxide is treated with methyl acetyl ricinoleate as a coupling agent.

Antimony trioxide functions as both a flame retardant and a filler because of the relatively large amounts often required to flame retard polypropylene compositions. Such antimony oxide often results in a loss in physicai properties of polyolefin composites.

In these examples, antimony oxide having a mean particle size distribution of about 1.5 microns was coated with 3% of methyl acetyl ricinoleate based on the antimony trioxide weight. The MAR treated antimony tiroxide was compounded with PP to provide a 16.7% loading on a 2 roll calender, compression molded and tested for tensile impact strength.

As controls, a PP resin containing no antimony trioxide and coupler and a PP resin/Sb203 composite containing 16.7% Sb203 alone was also tested. The results are given in Table 8 below: TABLE 8 Mar% Tensile Ex. Sb203 (based on Impact str. Ductility % Sb203 wt) (ft-lbs/in2) (millisecs) 72 0 0 133(32.1)* 1.2 73 16.7 0 90(21.7) 0.9 74 16.7 3 121 (29.2) 1.5 *Figures in brackets in N.m.cm -2 As Table 8 shows, MAR treated antimony trioxide/PP composite gave significant improvements on tensile impact strength and ductility over untreated antimony trioxide composite.

Examples 75 to 77 These examples illustrate the improvements in reinforcing properties of polypropylene resin filled with aluminum trihydrate (ATH) wherein the ATH is treated with methyl acetyl ricinoleate as a coupling agent.

Aluminum trihydrate is useful as both a flame/smoke retardant and filler in many thermoplastic applications.

In these examples, ATH having a mean particle size of about 1 micron was coated with 3% of methyl acetyl ricinoleate based on the ATH weight. The MAR treated ATH was compounded with PP to form a 25% loading using a 2-roll calender, compression molded and examined for tensile impact strength.

As controls, a PP resin without ATH and coupler and a PP resin/ATH composites containing 25% ATH alone was also tested. The results are given in Table 9.

TABLE 9 Mar% Tensile Ex. ATH % (based on Impact str.

ATH wt.) (ft-lbs/in2/ 75 6 0 106(25.6)* 76 25 0 35 (8.5) 77 25 3 80(19.3) * Figures in brackets in N.m.cm-2 Table 9 shows that MAR treated PP/ATH composites develop significant improvements in tensile impact strength over the untreated ATH composites.

Examples 78 to 81 These examples illustrate the improvement in reinforcing properties of polypropylene filled with the amounts of calcium carbonate (uncoated or coated) having a mean particle size distribution of 2.5 microns according to the procedure of Examples 1 to 6. The coupling agents used were docosylhydroxystearate wherein the alcohol is a by-product mixture containing C20 - C28 linear primary alcohols containing about 60% C22; and tetratriacontyl ricinoleate wherein the alcohol is a by-product mixture containing 65% C34 saturated primary alcohol and remainder being non-reactive material being 500 molecular weight normal paraffin.

As Table 10 shows, a significant improvement in reinforcing properties of calcium carbonate occurred when coated with the compositions of this invention.

The invention being thus described, it will be obvious that the same may be varied in many ways, such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following claims.

TABLE 10 Tensile impact str Ductility Ex Filler Coupling agent (ft-lbs/in2) milliseconds 78 NONE NONE 116(28)* 0.8 79 CaC03 NONE 77 (18.6) 0.7 80 CaC03 C22 plus ester 108(26.1) 1.0 of hydroxy stearic acid 81 CaC03 C36 ester of 85 (20.5) 0.7 recinoleic acid *Figures in brackets in N.m.cm-2.

Claims

1. A composition comprising a thermoplastic resin containing an inorganic mineral filler and a coupling agent which is one or more mono-, di- or tri long chain fatty acid esters of C1 to C36 mono or polyhydric alcohols.

2. A composition as claimed in claim 1 wherein the long chain fatty acid comprises hydroxy fatty acids or acetyl derivatives thereof.

3. A composition as claimed in claim 2 wherein the long chain fatty acid is acetyl ricinoleic acid, acetyl stearic acid, ricinoleic acid, or hydroxystearic acid.

4. A composition as claimed in claim 3 wherein the coupling agent is one or more of methyl ricinoleate, methyl acetyl rincinoleate, ethyl ricinoleate, ethyl acetyl ricinoleate, butyl ricinoleate, butyl acetyl ricinoleate, glyceryl ricinoleate and glyceryl tri (acetyl ricinoleate).

5. A composition as claimed in claim 3 wherein the coupling agent is one or more or methyl hydroxy stearate, methyl acetyl stearate, ethyl hydroxy stearate, ethyl acetyl stearate, butyl hydroxy stearate, butyl hydroxy stearate, butyl acetyl stearate, glyceryl tri (stearate) and glyceryl tri (acetyl stearate).

6. A composition as claimed in any one of claims 1 to 5 wherein the coupling agent comprises from about 0.5 to 7.5% by weight of the filler.

7. A composition as claimed in any one of claims 1 to 6 wherein the thermoplastic resin is the product of the polymerization of organic monomers containing one or more unsaturated double bonds.

8. A composition as claimed in claim 7 wherein the thermoplastic resin is one or more polymerized monomers of ethylene, propylene, styrene, acrylobutadiene styrene, methacrylic acid, vinyl acetate, vinyl chloride or a mixture thereof.

9. A composition as claimed in any one of claims 1 to 8 wherein the inorganic mineral filler is one or more silicas, metal silicates, metal oxides, hydrated aluminium oxides, antimony trioxide, calcium carbonate or a combination thereof.

10. A composition as claimed in any one of claims 1 to 9 and substantially as hereinbefore described.