WO1991008257A1 - Thermoplastic resin compositions - Google Patents
Thermoplastic resin compositions Download PDFInfo
- Publication number
- WO1991008257A1 WO1991008257A1 PCT/GB1990/001856 GB9001856W WO9108257A1 WO 1991008257 A1 WO1991008257 A1 WO 1991008257A1 GB 9001856 W GB9001856 W GB 9001856W WO 9108257 A1 WO9108257 A1 WO 9108257A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- silane
- grafted
- polyolefin
- thermoplastic resin
- blending
- Prior art date
Links
- 229920005992 thermoplastic resin Polymers 0.000 title claims abstract description 22
- 239000011342 resin composition Substances 0.000 title description 5
- 239000000203 mixture Substances 0.000 claims abstract description 55
- 238000002156 mixing Methods 0.000 claims abstract description 28
- 229920000098 polyolefin Polymers 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- -1 silane compound Chemical class 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 12
- 229920002397 thermoplastic olefin Polymers 0.000 claims abstract description 3
- 229920001971 elastomer Polymers 0.000 claims description 22
- 239000000806 elastomer Substances 0.000 claims description 16
- 229920001112 grafted polyolefin Polymers 0.000 claims description 15
- 239000004743 Polypropylene Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 10
- 229920001155 polypropylene Polymers 0.000 claims description 10
- 229920001169 thermoplastic Polymers 0.000 claims description 10
- 239000004416 thermosoftening plastic Substances 0.000 claims description 7
- 229920006014 semi-crystalline thermoplastic resin Polymers 0.000 claims description 6
- 150000001875 compounds Chemical class 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 2
- 239000005977 Ethylene Substances 0.000 claims description 2
- 229920002302 Nylon 6,6 Polymers 0.000 claims description 2
- 239000004952 Polyamide Substances 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- JZCCFEFSEZPSOG-UHFFFAOYSA-L copper(II) sulfate pentahydrate Chemical compound O.O.O.O.O.[Cu+2].[O-]S([O-])(=O)=O JZCCFEFSEZPSOG-UHFFFAOYSA-L 0.000 claims description 2
- WRUGWIBCXHJTDG-UHFFFAOYSA-L magnesium sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Mg+2].[O-]S([O-])(=O)=O WRUGWIBCXHJTDG-UHFFFAOYSA-L 0.000 claims description 2
- 229920013639 polyalphaolefin Polymers 0.000 claims description 2
- 229920002647 polyamide Polymers 0.000 claims description 2
- 229920000728 polyester Polymers 0.000 claims description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 2
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 2
- 229920000578 graft copolymer Polymers 0.000 claims 4
- 238000004132 cross linking Methods 0.000 abstract description 12
- 229910000077 silane Inorganic materials 0.000 abstract description 11
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 abstract description 9
- 238000005054 agglomeration Methods 0.000 abstract description 4
- 230000002776 aggregation Effects 0.000 abstract description 4
- 238000012545 processing Methods 0.000 abstract description 4
- HQQADJVZYDDRJT-UHFFFAOYSA-N ethene;prop-1-ene Chemical group C=C.CC=C HQQADJVZYDDRJT-UHFFFAOYSA-N 0.000 description 10
- 238000000748 compression moulding Methods 0.000 description 9
- FZHAPNGMFPVSLP-UHFFFAOYSA-N silanamine Chemical compound [SiH3]N FZHAPNGMFPVSLP-UHFFFAOYSA-N 0.000 description 5
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000004626 scanning electron microscopy Methods 0.000 description 3
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 2
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 description 2
- 150000008064 anhydrides Chemical group 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 239000012975 dibutyltin dilaurate Substances 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000001451 organic peroxides Chemical class 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 1
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 description 1
- 229920002943 EPDM rubber Polymers 0.000 description 1
- 229920000181 Ethylene propylene rubber Polymers 0.000 description 1
- 229920002292 Nylon 6 Polymers 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229920002367 Polyisobutene Polymers 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- 238000000071 blow moulding Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- FWDBOZPQNFPOLF-UHFFFAOYSA-N ethenyl(triethoxy)silane Chemical compound CCO[Si](OCC)(OCC)C=C FWDBOZPQNFPOLF-UHFFFAOYSA-N 0.000 description 1
- NKSJNEHGWDZZQF-UHFFFAOYSA-N ethenyl(trimethoxy)silane Chemical compound CO[Si](OC)(OC)C=C NKSJNEHGWDZZQF-UHFFFAOYSA-N 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 239000005038 ethylene vinyl acetate Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011953 free-radical catalyst Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229920001910 maleic anhydride grafted polyolefin Polymers 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000006069 physical mixture Substances 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920002285 poly(styrene-co-acrylonitrile) Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920001707 polybutylene terephthalate Polymers 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001195 polyisoprene Polymers 0.000 description 1
- 239000002952 polymeric resin Substances 0.000 description 1
- 229920006380 polyphenylene oxide Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 150000003606 tin compounds Chemical class 0.000 description 1
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 1
- 239000005052 trichlorosilane Substances 0.000 description 1
- QQQSFSZALRVCSZ-UHFFFAOYSA-N triethoxysilane Chemical compound CCO[SiH](OCC)OCC QQQSFSZALRVCSZ-UHFFFAOYSA-N 0.000 description 1
- YUYCVXFAYWRXLS-UHFFFAOYSA-N trimethoxysilane Chemical group CO[SiH](OC)OC YUYCVXFAYWRXLS-UHFFFAOYSA-N 0.000 description 1
- UKRDPEFKFJNXQM-UHFFFAOYSA-N vinylsilane Chemical compound [SiH3]C=C UKRDPEFKFJNXQM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
Definitions
- thermoplastic resin compositions having a normally immiscible polyolefin dispersed therein and to their production.
- thermoplastic resin with an immiscible resin such as an elastomeric polyolefin.
- immiscible resin such as an elastomeric polyolefin.
- the mechanical properties of the blend are often better in a significant respect, e.g. in relation to impact strength, than that of the unblended thermoplastic resin.
- the disperse phase of the polyolefin must be finely divided.. While such fine division is relatively easy to achieve during the actual blending, it is found that during subsequent processing, the particles of the finely divided disperse phase tend to agglomerate. Such agglomeration causes a change in the mechanical properties and processability and often leads to an unacceptably large and not always predictable change.
- thermoplastic resins having polyolefins dispersed therein Since consistency of properties of any thermoplastic resin composition is always important, such sensitivity to processing conditions constitutes an important disadvantage of known blends of thermoplastic resins having polyolefins dispersed therein. It has now been found that the morphology of such blends can be very substantially stabilized if the polyolefin blended with the thermoplastic resin is grafted with a silane compound and the silane compound is then cured by water during the blending operation. The curing brings about cross-linking of the polyolefin and this stabilises the dispersed particles and substantially reduces or eliminates the agglomeration of the particles which, in the absence of the cross-linking, may take place during processing. The mechanical properties of the blend are substantially unaltered, or even improved, by cross-linking of the polyolefin in this way. The impact strength, in particular, is often improved.
- thermoplastic resin composition comprising, as continuous phase, from 65 to 90% by weight of the composition of a semicrystalline thermoplastic resin and, as disperse phase from 35 to 10* by weight of a moisture-cured silane-grafted thermoplastic or elastomeric polyolefin having a particle size in the range of 0.1 to 2.5 ⁇ m.
- the novel thermoplastic compositions are produced by blending together (1) a semicrystalline thermoplastic resin and (2) a moisture- curable silane-grafted thermoplastic or elastomeric polyolefin in the presence of (3) water or a compound which releases water under the blending conditions, the conditions of blending and the proportions of the thermoplastic resin and polyolefin being such that ( ⁇ ) the thermoplastic resin (1) forms the continuous phase of the blend, (B) the silane- grafted polyolefin (2) is dispersed in the blend with a particle size substantially all in the range 0.1 to 2.5 ⁇ m, and (C) the silane-grafted polyolefin (2) is cured during the blending by the water (3).
- figures 1 and 2 show a composition comprising polypropylene as continuous phase and an ethylene/propylene elastomer as disperse phase as viewed by scanning electron microscopy before and after compression moulding respectively.
- Figures 3 and 4 show a similar composition in which however the ethylene/propylene elastomer has been silane-grafted in accordance with the present invention. These figures show the composition as viewed by scanning electron microscopy before and after compression moulding respectively. The compositions are described in detail in Example 1 below.
- thermoplastic resin used as continuous phase in the new compositions nay be any thermoplastic resin which can be shaped by compression or injection moulding and which is resistant to the blending conditions.
- the term "semicrystalline" as used herein in relation to the thermoplastic resin means that the polymer is crystallizable, i.e. substantially non-amorphous, but may contain amorphous zones within the polymer spherulite structures. A wide variety of such resins are available.
- the invention is especially advantageous when applied to blends based on polypropylene or other semicrystalline linear poly- ⁇ -olefin as the continuous phase, but other thermoplastic resins may be used, e.g.
- thermoplastic resins such as polyhexamethylene adipamide or polycaprolactam, or linear polyesters such as polyethylene terephthalate or polybutylene terephthalate or other thermoplastic polymers such as polycarbonate, polystyrene, polyacrylates, polyacrylonitrile, styrene- acrylonitrile copolymer, acrylonitrile-butadiene-styrene terpolymer, polymethyl methacrylates or polyphenylene oxide.
- thermoplastic resins are used in the proportions such that they constitute the continuous phase of the blend, and more particularly from 65 to 90%, preferably 65 to 75%, by weight of the total composition of semicrystalline thermoplastic resin and cured polyolefin.
- the silane-grafted polyolefin is conveniently made by one of the two following methods.
- the polyolefin starting material is either a thermoplastic resin such as polyethylene or an ethylene copolymer, e.g. an ethylene-vinylacetate copolymer, or an elastomeric polymer such as an ethylene-alpha ole in elastomer (such as ethylene- propylene copolymer or ethylene-propylene-diene terpolymer) or a polyisobutene or polyisoprene elastomer.
- a thermoplastic resin such as polyethylene or an ethylene copolymer, e.g. an ethylene-vinylacetate copolymer, or an elastomeric polymer such as an ethylene-alpha ole in elastomer (such as ethylene- propylene copolymer or ethylene-propylene-diene terpolymer) or a polyisobutene or polyisopre
- the polyolefin is first reacted with maleic anhydride in the presence of a free radical catalyst such as an organic peroxide and the maleic anhydride grafted polyolefin so obtained is then reacted with an amino silane, e.g. a gamma-aminopropyltriethoxysilane, which reacts with the anhydride residues and thus introduces triethoxysilane radicals into the polyolefin.
- a free radical catalyst such as an organic peroxide
- an amino silane e.g. a gamma-aminopropyltriethoxysilane
- the polyolefin is reacted directly with a vinyl-silane, e.g. a vinyl-trialkoxysilane such as vinyl-trimethoxysilane, in the presence of a free radical-generating catalyst which is preferably an organic peroxide such as dibenzoyl peroxide or other peroxide which is relatively stable at ambient temperature but which decomposes at elevated temperature with production of free radicals.
- a vinyl-silane e.g. a vinyl-trialkoxysilane such as vinyl-trimethoxysilane
- a free radical-generating catalyst which is preferably an organic peroxide such as dibenzoyl peroxide or other peroxide which is relatively stable at ambient temperature but which decomposes at elevated temperature with production of free radicals.
- the proportion of crosslinkable silane, preferably triethoxysilane, groups introduced into the polyolefin is preferably 0.2 to 0.5 per cent by weight, calculated as total silicon in the grafted polyolefin.
- the grafting of the silane with the polyolefin is generally carried out by a reaction extrusion or blending process (such as single or twin screw extrusion or Brabend ⁇ r mixing) .
- the latter and the thermoplastic polymer resin are blended together, e . g. in a Brabender mixer or any other suitable mixing device, at an elevated temperature, e. g. 150 to 250 *C, and preferably from 180 to 200*C, until the silane-grafted polyolefin has been finely dispersed in the continuous phase of the thermoplastic polymer.
- water or a water-releasing agent is employed in a proportion such as to bring about crosslinking of the trialkoxysilane groups in the silane grafted polyolefin .
- the dispersed silane-grafted phase becomes finely divided before crosslinking, as the impact an mechanical properties of the resultant blend depend on the particle size of the dispersed phase.
- Crosslinking of the dispersed phase during mixing enables good morphology control.
- a high intensity mixing device such as a twin screw compounder
- a suitable catalyst e.g. a tin compound such as dibutyltin dilaurate
- Crosslinking is preferably t at least 80% gel content in xylene.
- Water may be used as such during preparation of the blend, but it is also impossible to add the water in the for of a solid compound which releases water at the blending temperature.
- examples of such materials include hydrated alumina, and hydrated inorganic salts such as cupric sulphate pentahydrate and magnesium sulphate heptahydrate.
- Such hydrated salts must be chosen so as not to have any adverse effect upon the blend; this normally presents no problem with regard to mechanical properties of the blend, but use of such salts may lead to problems of blend appearance.
- the proportion should be such as to bring about crosslinking of all the crosslinkable silane groups, e.g.
- trichlorosilane or trialkoxysilane residues present in the silane-grafted polyolefin Generally about 10 to 20 per cent by weight of water based on the weight of silicon in the grafted polyolefin is appropriate, but when water is added to the blend while mixing, a large excess may need to be used to compensate for any loss due to evaporation.
- Vinyl tri ethoxysilane A171 of Union Carbide Company (1.5% by weight), dicumyl peroxide (0.15% by weight) and dibutyl tin dilaurate (0.05 weight per cent) were mixed with ethylene/propylene rubber (to 100%) in a Brabender mixer at 120 to 130*C. This causes the trimethoxysilane groups to become grafted to the ethylene/propylene rubber.
- the rubber employed was VISTALON 504 of Exxon Chemical Company, being an amorphous EP rubber containing 53 wt % ethylene and having a Mooney viscosity M (1+8) at 100"C of 38.
- Polypropylene was melted in a Brabender mixer at 200*C and 30% by weight of the silane-grafted ethylene/ propylene elastomer produced in the manner just described was then added.
- the polypropylene used was V ⁇ 8020H of Neste Oy, a homopolymer of melt flow rate at 230*C/2.16kg of 0.8, suitable for blow moulding, of density 0.902. After about 5 minutes mixing, water (5 per cent by weight) was added and the mixing was continued until the reaction was substantially complete.
- the blend obtained was examined by scanning electron microscopy and the crosslinked ethylene/propylene elastomer phase was found to be present in the blend in the form of 1 to 2 ⁇ m particles which were 80% insoluble as determined by xylene extraction (representing a high degree of crosslinking) .
- the disperse phase of crosslinked elastomer showed no tendency to agglomerate upon compression moulding, as evidenced by the results of further scanning electron microscope (SEM) analysis of the blend after it had been compression moulded at 180 * C/20 tonnes for 30 minutes in a Fontijne type SRB140 compression moulder.
- a comparison blend was prepared using the same mixing conditions as expressed above, using exactly the same additives in the mixer; however in this case the ethylene/propylene elastomer which was added to the mixer was not grafted with vinyltrimethoxysilan ⁇ .
- the particle size of the dispersed phase EP increased from l-2 ⁇ m to >10 ⁇ m after compression moulding at the same conditions as the silane-grafted EP/PP blend.
- the properties of the blends are shown in. the following Table, in which the values quoted for mechanical properties represent the average of five measurements.
- Blend 1 Blend 2 (invention) polypropylene 70 70 ethylene/ propylene elastomer 30 0 silane-grafted ethylene/ propylene elastomer 0 30 impact strength (J/m) room temperature 569 563
- the polypropylene by itself has, at room temperature, an impact strength of 43.4 J/m and an E-modulus of 0.84 GPa.
- Maleic anhydride-grafted ethylene/propylene elastomer (containing 0.7 per cent by weight of maleic anhydride) was mixed at 120 * C in a first Brabender mixer operating at 50 revolutions per minute (rpm) , with gamma- aminopropyltriethoxysilane in a proportion of twice the stochiometric amount (i.e. in the proportion of two NH 2 groups for each anhydride residue) . This causes the aminosilane to become grafted onto the maleated EP rubber.
- the polypropylene used was V ⁇ 802OH as used in Example 1.
- the maleic anhydride grafted EP rubber was EXXELOR V ⁇ 1803 of Exxon Chemical Company, being an EP rubbe of melt index 3g/10 min (ASTM D 1238) and maleic anhydride content 0.7 wt %.
- the aminopropyltriethoxy silane used was A1100 of Union Carbide Company.
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Abstract
The morphology of two-phase mixtures comprising a thermoplastic resin as continuous phase having finely divided elastomeric or thermoplastic polyolefin dispersed therein is stabilized by grafting the polyolefin with a silane compound and then cross-linking the silane with water during the blending of the silane-grafted polyolefine with the thermoplastic resin. The compositions so obtained resist particle agglomeration during processing and thus retain their mechanical properties better.
Description
"THERMOPLASTIC RESIN COMPOSITIONS" This invention relates to thermoplastic resin compositions having a normally immiscible polyolefin dispersed therein and to their production.
It is common practice to blend a thermoplastic resin with an immiscible resin such as an elastomeric polyolefin. The mechanical properties of the blend are often better in a significant respect, e.g. in relation to impact strength, than that of the unblended thermoplastic resin. For optimum properties, the disperse phase of the polyolefin must be finely divided.. While such fine division is relatively easy to achieve during the actual blending, it is found that during subsequent processing, the particles of the finely divided disperse phase tend to agglomerate. Such agglomeration causes a change in the mechanical properties and processability and often leads to an unacceptably large and not always predictable change. Since consistency of properties of any thermoplastic resin composition is always important, such sensitivity to processing conditions constitutes an important disadvantage of known blends of thermoplastic resins having polyolefins dispersed therein. It has now been found that the morphology of such blends can be very substantially stabilized if the polyolefin blended with the thermoplastic resin is grafted with a silane compound and the silane compound is then cured by water during the blending operation. The curing brings about
cross-linking of the polyolefin and this stabilises the dispersed particles and substantially reduces or eliminates the agglomeration of the particles which, in the absence of the cross-linking, may take place during processing. The mechanical properties of the blend are substantially unaltered, or even improved, by cross-linking of the polyolefin in this way. The impact strength, in particular, is often improved.
The present invention accordingly provides a thermoplastic resin composition comprising, as continuous phase, from 65 to 90% by weight of the composition of a semicrystalline thermoplastic resin and, as disperse phase from 35 to 10* by weight of a moisture-cured silane-grafted thermoplastic or elastomeric polyolefin having a particle size in the range of 0.1 to 2.5μm.
While it has previously been proposed to produce blends of a polyolefin and a silane-grafted ethylene propylene elastomer which is cured, see British Specificatio 2116986 (Exxon Research and Engineering Co) , in the known compositions the elastomeric polymer constituted the continuous phase and there was no teaching that the cross- linking of the silane-grafted elastomer should take place during the operation of blending the elastomer with the polyolefin. According to a feature of the invention, the novel thermoplastic compositions are produced by blending together
(1) a semicrystalline thermoplastic resin and (2) a moisture- curable silane-grafted thermoplastic or elastomeric polyolefin in the presence of (3) water or a compound which releases water under the blending conditions, the conditions of blending and the proportions of the thermoplastic resin and polyolefin being such that (λ) the thermoplastic resin (1) forms the continuous phase of the blend, (B) the silane- grafted polyolefin (2) is dispersed in the blend with a particle size substantially all in the range 0.1 to 2.5 μm, and (C) the silane-grafted polyolefin (2) is cured during the blending by the water (3).
In the accompanying drawings, figures 1 and 2 show a composition comprising polypropylene as continuous phase and an ethylene/propylene elastomer as disperse phase as viewed by scanning electron microscopy before and after compression moulding respectively. Figures 3 and 4 show a similar composition in which however the ethylene/propylene elastomer has been silane-grafted in accordance with the present invention. These figures show the composition as viewed by scanning electron microscopy before and after compression moulding respectively. The compositions are described in detail in Example 1 below.
The thermoplastic resin used as continuous phase in the new compositions nay be any thermoplastic resin which can be shaped by compression or injection moulding and which is resistant to the blending conditions. The term
"semicrystalline" as used herein in relation to the thermoplastic resin means that the polymer is crystallizable, i.e. substantially non-amorphous, but may contain amorphous zones within the polymer spherulite structures. A wide variety of such resins are available. The invention is especially advantageous when applied to blends based on polypropylene or other semicrystalline linear poly-α-olefin as the continuous phase, but other thermoplastic resins may be used, e.g. linear polyamides such as polyhexamethylene adipamide or polycaprolactam, or linear polyesters such as polyethylene terephthalate or polybutylene terephthalate or other thermoplastic polymers such as polycarbonate, polystyrene, polyacrylates, polyacrylonitrile, styrene- acrylonitrile copolymer, acrylonitrile-butadiene-styrene terpolymer, polymethyl methacrylates or polyphenylene oxide. As already indicated, such thermoplastic resins are used in the proportions such that they constitute the continuous phase of the blend, and more particularly from 65 to 90%, preferably 65 to 75%, by weight of the total composition of semicrystalline thermoplastic resin and cured polyolefin.
The silane-grafted polyolefin is conveniently made by one of the two following methods. In either case the polyolefin starting material is either a thermoplastic resin such as polyethylene or an ethylene copolymer, e.g. an ethylene-vinylacetate copolymer, or an elastomeric polymer such as an ethylene-alpha ole in elastomer (such as ethylene-
propylene copolymer or ethylene-propylene-diene terpolymer) or a polyisobutene or polyisoprene elastomer.
In the first method of forming the silane-grafted polyolefin, the polyolefin is first reacted with maleic anhydride in the presence of a free radical catalyst such as an organic peroxide and the maleic anhydride grafted polyolefin so obtained is then reacted with an amino silane, e.g. a gamma-aminopropyltriethoxysilane, which reacts with the anhydride residues and thus introduces triethoxysilane radicals into the polyolefin.
In a second method, the polyolefin is reacted directly with a vinyl-silane, e.g. a vinyl-trialkoxysilane such as vinyl-trimethoxysilane, in the presence of a free radical-generating catalyst which is preferably an organic peroxide such as dibenzoyl peroxide or other peroxide which is relatively stable at ambient temperature but which decomposes at elevated temperature with production of free radicals.
With either method, and indeed with other methods which are available to those skilled in the art, the proportion of crosslinkable silane, preferably triethoxysilane, groups introduced into the polyolefin is preferably 0.2 to 0.5 per cent by weight, calculated as total silicon in the grafted polyolefin. The grafting of the silane with the polyolefin is generally carried out by a reaction extrusion or blending process (such as single or
twin screw extrusion or Brabendβr mixing) .
Whichever method of preparing the silane grafted polyolefin is used, the latter and the thermoplastic polymer resin are blended together, e . g. in a Brabender mixer or any other suitable mixing device, at an elevated temperature, e. g. 150 to 250 *C, and preferably from 180 to 200*C, until the silane-grafted polyolefin has been finely dispersed in the continuous phase of the thermoplastic polymer. During the blending and after the silane grafted polyolefin is well dispersed, water or a water-releasing agent is employed in a proportion such as to bring about crosslinking of the trialkoxysilane groups in the silane grafted polyolefin . It is greatly preferred that the dispersed silane-grafted phase becomes finely divided before crosslinking, as the impact an mechanical properties of the resultant blend depend on the particle size of the dispersed phase. Crosslinking of the dispersed phase during mixing enables good morphology control. A high intensity mixing device (such as a twin screw compounder) is preferred for making the blend. To promote this crosslinking a suitable catalyst e.g. a tin compound such as dibutyltin dilaurate , may be incorporated i the blend in a suitable proportion, e.g. 0.05 to 0.1 per cen by weight of the total of semicrystalline thermoplastic resi and silane grafted polyolefin. Crosslinking is preferably t at least 80% gel content in xylene.
Water may be used as such during preparation of the
blend, but it is also impossible to add the water in the for of a solid compound which releases water at the blending temperature. Examples of such materials include hydrated alumina, and hydrated inorganic salts such as cupric sulphate pentahydrate and magnesium sulphate heptahydrate. Such hydrated salts must be chosen so as not to have any adverse effect upon the blend; this normally presents no problem with regard to mechanical properties of the blend, but use of such salts may lead to problems of blend appearance. In whatever form the water is added, the proportion should be such as to bring about crosslinking of all the crosslinkable silane groups, e.g. trichlorosilane or trialkoxysilane residues present in the silane-grafted polyolefin. Generally about 10 to 20 per cent by weight of water based on the weight of silicon in the grafted polyolefin is appropriate, but when water is added to the blend while mixing, a large excess may need to be used to compensate for any loss due to evaporation.
The following Examples illustrate the invention. EXAMPLE 1
Vinyl tri ethoxysilane A171 of Union Carbide Company (1.5% by weight), dicumyl peroxide (0.15% by weight) and dibutyl tin dilaurate (0.05 weight per cent) were mixed with ethylene/propylene rubber (to 100%) in a Brabender mixer at 120 to 130*C. This causes the trimethoxysilane groups to become grafted to the ethylene/propylene rubber. The rubber
employed was VISTALON 504 of Exxon Chemical Company, being an amorphous EP rubber containing 53 wt % ethylene and having a Mooney viscosity M (1+8) at 100"C of 38.
Polypropylene was melted in a Brabender mixer at 200*C and 30% by weight of the silane-grafted ethylene/ propylene elastomer produced in the manner just described was then added. The polypropylene used was Vλ 8020H of Neste Oy, a homopolymer of melt flow rate at 230*C/2.16kg of 0.8, suitable for blow moulding, of density 0.902. After about 5 minutes mixing, water (5 per cent by weight) was added and the mixing was continued until the reaction was substantially complete. The blend obtained was examined by scanning electron microscopy and the crosslinked ethylene/propylene elastomer phase was found to be present in the blend in the form of 1 to 2 μm particles which were 80% insoluble as determined by xylene extraction (representing a high degree of crosslinking) . The disperse phase of crosslinked elastomer showed no tendency to agglomerate upon compression moulding, as evidenced by the results of further scanning electron microscope (SEM) analysis of the blend after it had been compression moulded at 180*C/20 tonnes for 30 minutes in a Fontijne type SRB140 compression moulder. A comparison blend was prepared using the same mixing conditions as expressed above, using exactly the same additives in the mixer; however in this case the ethylene/propylene elastomer which was added to the mixer was not grafted with
vinyltrimethoxysilanβ. For this comparison blend the particle size of the dispersed phase EP increased from l-2μm to >10 μm after compression moulding at the same conditions as the silane-grafted EP/PP blend. The properties of the blends are shown in. the following Table, in which the values quoted for mechanical properties represent the average of five measurements.
Blend 1 Blend 2 (invention) polypropylene 70 70 ethylene/ propylene elastomer 30 0 silane-grafted ethylene/ propylene elastomer 0 30 impact strength (J/m) room temperature 569 563
-20'C 95 96
-40*C 66 73 E-modulus (GPa) 0.61 0.437 elongation at break (%) 604 12.5 stress at break (MPa) 18.2 12.3
For comparison, it may be stated that the polypropylene by itself has, at room temperature, an impact strength of 43.4 J/m and an E-modulus of 0.84 GPa.
The results shown in the Table demonstrate that the blend (2) of the invention has substantially the same mechanical properties as the comparison blend (1) [except for elongation at break]. However blend (2) has the advantage of
being reprocessable and exhibits an extremely stable phase morphology. This is shown in the accompanying drawings, in which Figures 1 and 2 show blend (1) as viewed by SEM before and after compression moulding, respectively; and Figures 3 and 4 show blend (2) as viewed by SEM before and after compression moulding, respectively. EXAMPLE 2
Maleic anhydride-grafted ethylene/propylene elastomer (containing 0.7 per cent by weight of maleic anhydride) was mixed at 120*C in a first Brabender mixer operating at 50 revolutions per minute (rpm) , with gamma- aminopropyltriethoxysilane in a proportion of twice the stochiometric amount (i.e. in the proportion of two NH2 groups for each anhydride residue) . This causes the aminosilane to become grafted onto the maleated EP rubber. 70 parts by weight of polypropylene ^ras melted at 180*C in a second Brabender mixer operated at 50 rpm , and 30 parts by weight of the silane-grafted maleated EP produced in the first Brabender mixer, was added. Mixing was continued whilst raising the temperature by shear heating to 196'C, at which point water (5 parts by weight) was added while the speed of the mixer was reduced from 50 to 30 rpm. Blending was completed when the temperature reached 210*C. A rise in torque of + INm was observed, indicating that curing had occurred.
The polypropylene used was Vλ 802OH as used in
Example 1. The maleic anhydride grafted EP rubber was EXXELOR Vλ 1803 of Exxon Chemical Company, being an EP rubbe of melt index 3g/10 min (ASTM D 1238) and maleic anhydride content 0.7 wt %. The aminopropyltriethoxy silane used was A1100 of Union Carbide Company.
The experiment was repeated without the pre-reaction of amino-silane and maleated EP. In this case a physical mixture of 1.5 parts by weight amino-silane and 30 parts by weight maleated EP was added to 70 parts by weight of the polypropylene while being blended at 180*0 in a Brabender mixer. Water (5 parts by weight) was then added as in the previous experiment. The mixer was operated at 50 rpm and the rise in torque observed was 2 Nm.
In a third experiment the blending of the same ingredients was repeated except that no aminosilane was included.
Comparison of the three blends after compression moulding at 190*0/20 tonnes for 20 minutes showed that the first two blends in accordance with the invention retained their mechanical properties very well during the compression moulding operating while the third (containing no cross- linked silane residues) showed considerable agglomeration of the dispersed elastomer particles which caused substantial deterioration in the mechanical properties.
Claims
1. A thermoplastic composition comprising, as continuous phase, from 65 to 90% by weight of the compositi of a semicrystalline thermoplastic resin and, as disperse phase, from 35 to 10% by weight of the composition of a moisture-cured silane-grafted thermoplastic or elastomeric polyolefin having a particle size in the range of O.lμm to 2.5 μ .
2. A composition according to claim 1 wherein the semicrystalline thermoplastic resin is a linear poly-α- olefin, a linear polyamide, or a linear polyester.
3. A composition according to claim 2 in which th thermoplastic resin is polypropylene, polyhexamethylene adipamide, or polyethylene terephthalate. . A composition according to any one of claims o
1 to 3 wherein the silane-grafted polymer is an elastomeric polyolefin.
5. A composition according to claim 4 wherein the silane-grafted polymer is a silane-grafted ethylene/propyle elastomer.
6. A composition according to claim 4 wherein the silane-grafted polymer is a silane-grafted maleic anhydride modified ethylene/propylene elastomer.
7. A composition according to any one of claims 1 to 6 comprising from 65 to 75% by weight of the thermoplast resin and from 35 to 25% by weight of the silane-grafted polymer.
8. A process for producing a thermoplastic composition which comprises blending together (1) a semicrystalline thermoplastic resin and (2) a moisture curable silane-grafted elastomeric or thermoplastic polyolefin in the presence of (3) water or a compound which releases water under the blending conditions, the conditions of blending and the proportions of the thermoplastic resin and the silane-grafted polyolefin being such that (A) the thermoplastic resin (1) forms the continuous phase of the blend, (B) the silane-grafted polyolefin (2) is dispersed in the blend with a particle size substantially all in the range O.lμm to 2.5μm, and (C) the silane-grafted polyolefin (2) is cured during the blending by the water (3) .
9. Process according to claim 8 wherein the blending is effected at a temperature in the range 150*C to 250*0.
10. Process according to claim 8 or 9 in which the water is added as hydrated alumina, cupric sulphate pentahydrate, or magnesium sulphate heptahydrate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8927173.8 | 1989-12-01 | ||
| GB898927173A GB8927173D0 (en) | 1989-12-01 | 1989-12-01 | Thermoplastic resin composition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1991008257A1 true WO1991008257A1 (en) | 1991-06-13 |
Family
ID=10667251
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB1990/001856 WO1991008257A1 (en) | 1989-12-01 | 1990-11-29 | Thermoplastic resin compositions |
Country Status (5)
| Country | Link |
|---|---|
| AR (1) | AR244742A1 (en) |
| AU (1) | AU6958391A (en) |
| GB (1) | GB8927173D0 (en) |
| PL (1) | PL288033A1 (en) |
| WO (1) | WO1991008257A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0510559A3 (en) * | 1991-04-22 | 1992-12-30 | Continental Aktiengesellschaft | Thermoplastic elastomer and method for preparing the same |
| EP0940439A1 (en) * | 1998-03-03 | 1999-09-08 | Hüls Aktiengesellschaft | Crosslinkable moldings. |
| WO1999067330A1 (en) * | 1998-06-22 | 1999-12-29 | Ck Witco Corporation | Silane vulcanized thermoplastic elastomers |
| WO2006113180A1 (en) * | 2005-04-14 | 2006-10-26 | General Electric Company | Silylated thermoplastic vulcanizate compositions |
| WO2006124368A1 (en) * | 2005-05-13 | 2006-11-23 | Momentive Performance Materials Inc. | Crosslinked polyethylene compositions |
| CN114230909A (en) * | 2021-12-09 | 2022-03-25 | 上海日之升科技有限公司 | Wear-resistant creep-resistant polypropylene composite material and preparation method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2030899A5 (en) * | 1968-12-20 | 1970-11-13 | Midland Silicones Ltd | |
| GB2116989A (en) * | 1982-03-23 | 1983-10-05 | Mitsubishi Petrochemical Co | Block copolymers of propylene butene-1 and optionally ethylene |
| EP0130855A1 (en) * | 1983-05-17 | 1985-01-09 | Alphacan | Thermoplastic polyolefinic composition with improved physical properties containing a silane-grafted polymer, and process for obtaining the improvement |
| EP0237713A2 (en) * | 1986-01-20 | 1987-09-23 | Sumitomo Bakelite Company Limited | Flame-retardant olefinic resin compositions |
| EP0361744A2 (en) * | 1988-09-16 | 1990-04-04 | MITSUI TOATSU CHEMICALS, Inc. | Polyolefin resin compositions and applications thereof |
-
1989
- 1989-12-01 GB GB898927173A patent/GB8927173D0/en active Pending
-
1990
- 1990-11-29 AU AU69583/91A patent/AU6958391A/en not_active Abandoned
- 1990-11-29 WO PCT/GB1990/001856 patent/WO1991008257A1/en not_active Application Discontinuation
- 1990-11-30 PL PL28803390A patent/PL288033A1/en unknown
- 1990-11-30 AR AR31851190A patent/AR244742A1/en active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2030899A5 (en) * | 1968-12-20 | 1970-11-13 | Midland Silicones Ltd | |
| GB2116989A (en) * | 1982-03-23 | 1983-10-05 | Mitsubishi Petrochemical Co | Block copolymers of propylene butene-1 and optionally ethylene |
| EP0130855A1 (en) * | 1983-05-17 | 1985-01-09 | Alphacan | Thermoplastic polyolefinic composition with improved physical properties containing a silane-grafted polymer, and process for obtaining the improvement |
| EP0237713A2 (en) * | 1986-01-20 | 1987-09-23 | Sumitomo Bakelite Company Limited | Flame-retardant olefinic resin compositions |
| EP0361744A2 (en) * | 1988-09-16 | 1990-04-04 | MITSUI TOATSU CHEMICALS, Inc. | Polyolefin resin compositions and applications thereof |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0510559A3 (en) * | 1991-04-22 | 1992-12-30 | Continental Aktiengesellschaft | Thermoplastic elastomer and method for preparing the same |
| EP0940439A1 (en) * | 1998-03-03 | 1999-09-08 | Hüls Aktiengesellschaft | Crosslinkable moldings. |
| JPH11293082A (en) * | 1998-03-03 | 1999-10-26 | Degussa Huels Ag | Crosslinkable molding material |
| WO1999067330A1 (en) * | 1998-06-22 | 1999-12-29 | Ck Witco Corporation | Silane vulcanized thermoplastic elastomers |
| AU744802B2 (en) * | 1998-06-22 | 2002-03-07 | General Electric Company | Silane vulcanized thermoplastic elastomers |
| US6448343B1 (en) | 1998-06-22 | 2002-09-10 | Crompton Corporation | Silane vulcanized thermoplastic elastomers |
| CZ302375B6 (en) * | 1998-06-22 | 2011-04-20 | General Electric Company | Thermoplastic vulcanizing composition and process for the preparation thereof |
| WO2006113180A1 (en) * | 2005-04-14 | 2006-10-26 | General Electric Company | Silylated thermoplastic vulcanizate compositions |
| WO2006124368A1 (en) * | 2005-05-13 | 2006-11-23 | Momentive Performance Materials Inc. | Crosslinked polyethylene compositions |
| CN114230909A (en) * | 2021-12-09 | 2022-03-25 | 上海日之升科技有限公司 | Wear-resistant creep-resistant polypropylene composite material and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| AU6958391A (en) | 1991-06-26 |
| PL288033A1 (en) | 1991-07-29 |
| GB8927173D0 (en) | 1990-01-31 |
| AR244742A1 (en) | 1993-11-30 |
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