SILANE VULCANIZED THERMOPLASTIC ELASTOMERS

Abstract: The formation of thermoplastic vulcanates may be accomplished with two polymers, wherein one polymer is grafted, or copolymerized with a carboxylic acid anhydride, which acid anhydride grafted polymer then is reacted with an animo silane, which reacts with the acid anhydride and then cross links.

Description: SILANE VULCANIZED THERMOPLASTIC ELASTOMERS Background of the Invention Thermoplastic elastomers (TPE) exhibit the functional properties of conventional thermoset rubbers, yet they can be melted repeatedly and are therefore suitable for processing in conventional thermoplastic fabrication equipment. The majority of TPE consist of two phases, one consisting of a rubber material (elastomer) that is insoluble in the other, and a flowable thermoplastic material. The rubber material is present as a dispersed phase and the thermoplastic is the continuous phase. Although it is in principle not necessary to crosslink the rubber in a TPE, it has proven efficient using crosslinking techniques to obtain better chemical resistance, mechanical properties and a better control of phase separation. Such TPE compositions where a crosslinking reaction and process is used to achieve phase separation into divided domains are called Thermoplastic Vulcanizates (TPV). To keep their thermoplastic character, it is essential that only the rubber phase be crosslinked. For an extensive and detailed description and review of TPV technology, see for instance S. Abdou-Sabet, R.C. Puydak and C.P. Rader in Rubber Chemistry and Technology, vol.69, pp 476-493, 1996. Furthermore, it has been demonstrated that the mechanical performance of TPVs improves with the degree of crosslinking of the rubbery phase and with the inverse of the particle size of rubbery domains. Dynamic crosslinking (which consists of intimately mixing a blend of compatible polymers, then introducing a crosslinking system in the mixture while the mixing process is continued) is used to generate the finely dispersed, highly crosslinked rubbery phase from a homogeneous blend of polymers. For thermodynamic and hydrodynamic reasons it is preferred that the polymer viscosity be increased while crosslinking is taking place, because the particles tend to agglomerate while the phases are separating. Moreover, if a phase-inversion process can take place while crosslinking, this is tavorable to the formation of fibrous rubber domains which may provide specific mechanical properties. However, it has been found preferable to select a crosslinking mechanism that can involve in part the thermoplastic phase, not to the point where the thermoplastic character of the TPV is removed, but only to achieve better adhesion and compatibihy of the polymers. The selection of a crosslinking process and chemicals is governed by processing requirements, e.g., reaction rate at the processing temperature; compatibility with the elastomer; side reactions with the thermoplastic; efficiency (number of crosslinks generated by each molecule of crosslinker); absence of undesired reactions; toxicity and hazards; color; and odor. One example of such TPVs is EPDM/PP descπbed in US Patent No. 3,130,535. EPDM and PP are mixed intimately in an internal mixer, and a peroxide is added to crosslink the EPDM. Excess peroxide and/or excessively high processing temperature and/or excessively reactive polymers will cause degradation of the PP phase and/or scorch. In contrast, insufficient amount of peroxide and/or too low processing temperature and/or a poorly reactive EPDM will cause insufficient crosslinking One deficiency of polyolefin-based TPVs is that they cannot be painted without a preliminary surface treatment. It was disclosed in US Patent No. 4,311,628 that other crosslinking agents can be used, e.g., dimethylol octyl phenol resm and sulfur Supeπor mechanical properties could be achieved, but unfortunately both systems suffer from excessive odor and/or yellowing of the resulting mateπals, as well as the difficult control of sulfur cure reactions It was disclosed in European Patent 0 324 434 to use silane-grafted polymers in the thermoplastic phase After mixing, the mateπal is shaped and left to react with atmospheπc moisture Thus it was possible to obtain a more elastomeπc mateπal after water cure. However the obtained water-cured item no longer contains a thermoplastic elastomer and cannot be recycled. To overcome this limitation, European Patent 0 409 542 disclosed mixing an EPR (ethylene-propylene rubber) or EPDM with a crystalline ethylene-propylene thermoplastic, an organofunctional silane and a free radical generator. The silane is grafted to the resin by the free radical generator and crosslinking takes place through reaction of the silane with water. A refinement of the above processes is disclosed in European Patent 0 510 559 where the EPR or EPDM first is grafted, then mixed to the thermoplastic PP and to a crosslinking additive compπsing water. The same process is disclosed using very low or ultra low density polyethylene (VLDPE or ULDPE) to reduce raw mateπals costs and lower mixing temperatures. See DE 44 02 943. It is also suggested to add simultaneously the PP component and the PE component together with silane and radical generator as a dry compound, the addition of water and condensation catalyst being made in a subsequent stage. However, the addition of water into an extruder at temperatures well above its boiling point is a difficult process. Moreover, the amount of water needed is so low that its meteπng requires sophisticated instrumentation in contradiction with the aim of the patent. U S. Patent No 4,146,529 to Yamamoto et al. discloses reacting an acid modified polypropylene with an amino or epoxy silane, but the purpose of such reaction is to use the alkoxy groups to bind to fillers and to react the non-grafted carboxylic anhydπde to form low odour, non-volatile products, not to crosslink the alkoxy functionalities amongst themselves The intent of these compositions is to couple mineral fillers and not to form thermoplastic vulcanizates; or, in the absence of filler, to tavor reaction of the amino or epoxy of the silane with free, volatile, non-gratted acid or anhydπde German Patent DE 196 29 429 teaches (amongst other issues) the use of pre-blends of vmyl silanes, am o silane and unsaturated carboxylic anhydπdes which are used for crosslinking of polyolefins respectively Bnef Descπption of the Drawings Figure 1-5 illustrate physical properties of TPVs made in the examples. Summary of the Invention The present invention teaches the manufacture of TPVs using polymers, carboxylic acid anhydπde and an amino silane. Detailed Descπption of the Invention The objectives of the present invention are to prepare new TPVs with a wide range of properties, low cost TPVs, paintable TPVs, to allow for the preparation of TPVs in conventional mixers without the need for expensive additional equipment, to avoid the use of high amounts of crosslinking agents (e.g., metal organics or peroxides) in the preparation of TPVs, and to obtain stable TPV compositions. COMPOSITION The TPVs are a blend of (a) a first polymer (rubber phase), (b) a crystalline or partly crystalline thermoplastic polymer (thermoplastic phase). (c) a carboxylic acid anhydride, incorporated as a comonomer in component (a) or grafted onto component (a); and (d) an aminosilane: which is allowed to crosslink. A. Polymers Suitable polyolefin rubber phase components (a) are any polymer which can be reacted such as to yield an carboxylic anhydride containing polymer like, e.g., ethylene propylene copolymer (EPR); ethylene propylene diene terpolymer (EPDM); butyl rubber (BR); natural rubber (NR); chlorinated polythylenes (CPE); silicone rubber; isoprene rubber (IR); butadiene rubber (BR); styrene-butadiene rubber (SBR); ethylene- vinyl acetate (EVA); ethylene butylacrylate (EBA), ethylene methacrylate (EMA), ethylene ethylacrylate (EEA), ethylene-α-olefin copolymers (e.g., EXACT and ENGAGE, LLDPE (linear low density polyethylene)), high density polyethylene (HDPE) and nitrile rubber (NBR). Polypropylene is not suitable as this phase since it has a tendency to degrade during crosslinking; however, if the polypropylene is a copolymer or graftomer of polypropylene with an acid anhydride, then it may be used. Preferably, the polymer is an ethylene polymer or copolymer with at least 50% ethylene content (by monomer), more preferably at least 70% of the monomers are ethylene. Suitable thermoplastic polymers (b) are polypropylene (PP); polyethylene, especially high density (PE); polystyrene (PS); acrylonitrile butadiene styrene (ABS); styrene acrylonitrile (SAN); polymethylmethacrylate (PMMA); thermoplastic polyesters (PET, PBT); polycarbonate (PC); and polyamide (PA). Such polymers may be made by any processes known in the art, including, but not limited to. by bulk phase, sluπy phase, gas phase, solvent phase, interfacial. polymeπzation (radical, ionic, metal initiated (e.g. metallocene, Ziegler-Natta)), polycondensation, polyaddition or combinations of these methodologies. It is possible to have the polymers for the two phases be the same wherein the acid anhydride is pre-added to one part of the polymer, which pre-reacted polymer will act as the rubber phase within the TPV. Such pre-addition includes the possibilities of having the acid anhydride present as a comonomer in the polymer or pre-reacting the acid anhydride with the polymer. In either of these two cases, the addition of the separate acid anhydride would not be necessary since it is present in the polymer. Given this level of complexity, it is preferred that the two polymers be different from each other. A third alternative is that the polymer of the rubber phase and the thermoplastic phase may the same polymer, but the acid anhydride is added to the polymer as a whole. In such a case when the silane is added part of the polymer would form the rubber phase, while another part would not react (given the relatively small amount of anhydride and silane present). It is important that a proper degree of phase separation is between the rubber and thermoplastic phases created during the process. This process would not necessarily lead to a TPV because one may not necessarily achieve the necessary phase without adding significantly to process complexity, and thus is not prefeπed. In the case of two different polymers, the polymer that is more reactive with the acid anhydride will be grafted by the acid anhydride and will act as the rubber phase in the TPV. The polymer which is to become the rubber phase must be extrudable and should be capable of grafting with the acid anhydride. The melting point of the thermoplastic phase should be less than the decomposition temperature of the aminosilane, as well as the decomposition temperature of the acid anhydπde (unless the acid anhydπde is a comonomer in the polymer). The polymers may have unimodal. bimodal or multimodal molecular weight distπbutions. The melt flow of the polymers may be any of those known in the art for use m forming thermoplastics and rubbers. B. Carboxylic Acid Anhydπdes Any carboxylic acid anhydπdes which can be grafted onto the polymer to be the rubber phase by any possible mechanism may be used. It is preferable, that there be an unsaturation either in the polymer, or more preferably, in the acid anhydπde, to accomplish this grafting. The unsaturation of the carboxylic acid anhydπde may be internal or external to a πng structure, if present, so long as it allows for reaction with the polymer. The acid anhydπde may include hahdes. Mixtures of different carboxylic acid anhydπdes may be used. Exemplary unsaturated carboxylic acid anhydπdes to use are lsobutenylsuccimc, (+/-)-2-octen-l-ylsuccmιc, ltaconic, 2-dodecen-l-ylsuccimc, cιs-l,2,3,6-tetrahydrophthahc, cιs-5-norbornene-endo-2,3-dιcarboxyhc, endo-bιcyclo[2.2.2]oct-5-ene-2,3-dιcarboxyhc, methyl-5-norbornene-2,3-carboxyhc, exo-3,6-epoxy-l,2,3,6-tetrahydrophthahc, maleic, citraconic, 2,3 dimethylmaleic, l-cyclopentene-l,2-dicarboxyhc, 3,4,5,6-tetrahydrophthahc, bromomaleic, and dichloromaleic anhydπdes. These acid anhydπdes may be present as a comonomer in the polymer of the rubber phase or be grafted onto the polymer which will be the rubber phase. The amount of acid anhydπde to use is 0 01 to 1 0 wt% based on the total amount ot polymer present C. Amino silanes The ammo silanes tor use herein have at least one hydrolyzable group, e.g., alkoxy, acetoxy or halo, preferably alkoxy. Preferably, there are at least two such hydrolyzable groups capable of undergoing crosslinking condensation reaction so that the resulting compound is capable of undergoing such crosslinking. A mixture of different amino silanes may be used. The amme must have a sufficient rate of reaction with the acid anhydπde. Generally, tertiary amines do not react appropπately with the acid anhydπde and should be avoided. The amino group may be bπdged to the silicon atom by a branched group to reduce yellowing of the resulting composition. The silane may be represented by the formula YNHBSι(OR) a (X) 3 - a , wherein a=l to 3, preferably 3, Y is hydrogen, an alkyl, alkenyl, hydroxy alkyl, alkaryl, alkylsilyl, alkylamine, C(=O)OR or C(=O)NR, R is an acyl, alkyl, aryl or alkaryl, X may be R or halo. B is a divalent bπdging group, which preferably is alkylene. which may be branched (e.g., neohexylene) or cyclic. B may contain heteroatom bπdges, e.g., an ether bond. Preferably B is propylene. Preferable R is methyl or ethyl. Methoxy containing silanes may ensure a better crosslinking performance than ethoxy groups. Preferably, Y is an amino alkyl, hydrogen, or alkyl. More preferably, Y is hydrogen or a pπmary ammo alkyl (e.g., ammoethyl). Preferable X are Cl and methyl, more preferably methyl. Examplary silanes are γ-amino propyl tπmethoxy silane (SELQUEST® A-1110 silane from Witco Corp., Greenwich, CT, USA), γ -amino propyl tπethoxy silane (SELQUEST A-l 100); γ -amino propyl methyl diethoxy silane; 4-amιno-3,3-dιmethyl butyl tπethoxy silane, 4-amιno-3,3-dιmethyl butyl methyldiethoxysilane. N-β-(amιnoethyl)- γ-amιnopropyltπmethoxysιlane (SILQUEST A- 1120), H 2 NCH2CH2NHCH2CH2NH(CH2) 3 Sι(OCH 3 (SILQUEST A-1130) and N-β-(amιnoethyl)-γ-amιnopropylmethyldιmethoxysιlane (SILQUEST A-2120). Other suitable amino silanes are as follows: 3-(N-allylamιno)propyltπmethoxysιlane, 4-amιnobutyltπethoxysιlane, 4-amιnobutyltπmethoxysιlane, (amιnoethylamιnomethyl)phenethyltπmethoxysιlane, ammophenyltπmethoxysilane, 3-(l-amιnopropoxy)-3,3,dιmethlyl-l-propenyltπmethoxysιlane, bιs[(3-tπmethoxysιlyl)propyl]ethylenedιamιne, N-methylaminopropyltπmethoxysilane, bιs-(γ-tπethoxysιlylpropyl) am e (SILQUEST A-1170), and N-phenyl-γ-ammopropyltπmethoxysilane (SILQUEST Y-9669). If the ammo silane is a latent aminosilane, i.e., a ureidosilane or a carbamatosilane, then the blending temperature must be sufficient so that the respective blocking group comes off from the amme and allows the amine to react with the acid anhydπde functionality, about 150 to 230°C. Examples of such latent ammosilanes are tert-butyl-N-(3-tπmethoxysιlylpropyl) carbamate, ureidopropyltπethoxysilane, and ureidopropyltπmethoxysilane. Other carbamato silanes which may be used are disclosed in US Patent No. 5,220,047, which is incorporated herein by reference. Preferably, so as to avoid the additional complexity of deblocking, the ammo silane is not such a latent ammo silane. The amino silane should be present at 250 to 25,000 ppm based on weight of both polymers. It should also be present at a molar equivalency ratio to the acid anhydπde of about 0.1 to 10, more preferably 0.9 to 1.1, most preferably, about a 1.1 ratio. The silane may be earned on a earner such as a porous polymer, silica, titanium dioxide or carbon black so that it is easy to add to the polymer duπng the mixing process Exemplary such material are ACCUREL polyolefin (Akzo Nobel), STAMYPOR polyolefin (DSM) and VALTEC polyolefin (Montell), SPHERILENE polyolefin (Montell), AEROSIL silica (Degussa). MICRO-CEL E (Manville) and ENSACO 350G carbon black (MMM Carbon). E. Optional Additives A free radical generator would be required if the carboxylic acid anhydride is being grafted by a free radical mechanism onto the polymer, but it is not required if the acid anhydride is either grafted via another mechanism or being a comonomer of the polymer. Suitable free-radical catalysts may be selected from the group of water soluble or oil soluble peroxides, such as hydrogen peroxide, ammonium persulfate, potassium persulfate, various organic peroxy catalysts, such as dialkyl peroxides, e.g., diisopropyl peroxide, dilauryl peroxide, di-t-butyl peroxide, di (2-t-butylperoxyisopropyl)benzene; 3,3,5-trimethyl l,l-di(tert-butyl peroxy) cylohexane; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2.5-dimethyl-2.5-di(t-butylperoxy)hexyne-3; dicumyl peroxide, alkyl hydrogen peroxides such as t-butyl hydrogen peroxide, t-amyl hydrogen peroxide, cumyl hydrogen peroxide, diacyl peroxides, for instance acetyl peroxide, lauroyl peroxide, benzoyl peroxide, peroxy ester such as ethyl peroxybenzoate, and the azo compounds such as 2-azobis(isobutyronitrile). The free radical generator may be present at 1/100 to 1/1 based on the molar quantity of the acid anhydride. Standard additives such as stabilizers (UV, light or aging), antioxidants, metal deactivators, processing aids, waxes, fillers (silica, TiO 2 , CaCO 3 , Mg(OH) 2 , carbon black, etc.), and colorants may be added to the TPVs. Additionally, blowing agents may be added to the polymers so that when they are extruded the polymer will form a foam. Examples of such blowing agents are volatile hydrocarbons, hydrofluorocarbons, and chlorofluorocarbons. Commonly known foaming agent like azocarbonamide or sodium bicarbonate (aka sodium hydrogen carbonate) decompose at elevated temperature to yield gaseous products. These are all chemic'al foaming processes. Foams can also be produced by injection of liquid or gaseous foaming agent into the polymer melt. Examples are, e.g., butane, CO 2 , nitrogen, water, helium, etc. The amount of such a blowing agent should be at 0.1 to 50 weight percent of the polymers. Process In a first reaction the carboxylic acid anhydπde is grafted (most preferably by a free radical mechanism) onto the rubber phase polymer. Said reaction may be done with both polymers present or with the two polymers separated, though it is preferred to accomplish this with both polymers present. As stated before, alternatively, this step may be effectively accomplished by the inclusion of the carboxylic acid anhydπde as a comonomer in the rubber phase polymer (in which case, no free radical generator is necessary). The polymer should be grafted/copolymeπzed with carboxylic acid anhydπde pπor to the reaction with aminosilane, since the reaction product between acid anhydπde and ammo silane has only a poor grafting efficiency. A pπor reaction between aminosilane and acid anhydπde would result in the formation of a semiamide, which could have infeπor grafting properties. In this case, no crosslinking would occur. In contrast, partial degradation of the polymer and/or the plasticizing effect of the semiamide may lead to a nse in melt flow index (MFI). It is preferable to add free radical generator with the anhydnde duπng the grafting step to induce the gratting of the acid anhydπde onto the rubber phase polymer. If the second, thermoplastic polymer is not present duπng the gratting, then it should be blended in with the grafted rubber phase polymer pπor to the addition of the aminosilane; however, such method suffers deficiency in terms of the mechanical propeπies of the resulting TPV. The second step is the addition of the ammo silane to the rubber phase grafted polymer/thermoplastic polymer blend. No water and/or catalyst need be added. This is a very fast reaction between amino silane and the grafted acid anhydπde. The reaction of a grafted acid anhydπde moiety with γ-ammopropylsilane may be viewed as: The reaction between the silane and the grafted acid anhydπde moiety has to be fast to obtain a cross nkable mateπal and faster than the reaction between the alkoxy groups and the acid anhydπde. A retarded reaction could occur concurrently with the crosslinking of the alkoxy moieties, " which could prevent crosslinking. The reaction between ammo group and anhydπde is very fast when using, e.g., pπmary amino groups. The reaction may be slowed down by employing secondary amino groups. Moreover, this step should be one at an elevated temperature, e.g., from 50 to 200°C depending on the polymer blend. Preferably, the polymer blend is in a melt stage when the ammo silane is added to the polymer. After the amino silane is grafted onto the one polymer, it should be allowed to crosslink, so as to form the gel phase of the crosslinked polymer. No separate moisture cure needs to take place. A condensation catalyst may be used to expedite the crosslinking process, though the semi-amide should be a sufficient catalyst. One to ten minutes at an elevated temperature of 60 to 200°C should ensure such crosslinking occurs. It has to be noted that the total amount of additives is only 0.4 % of the total composition, about five times less than the amount needed for peroxide or vinyl silane cure. This benefits in two ways, a reduction in total cost and a reduction of fugitive peroxides, which can present safety issues. During and after crosslinking, all of the ingredients should be blended in an internal mixer. The mixer may be an extruder (single screw, twin screw, etc.), a BUSS KO-KNEADER mixer or a simple internal type mixer. The conditions for mixing depend on the polymers and degree of crosslinking. Properties The resulting product is a thermoplastic vulcanisate with excellent mechanical properties. The crosslinked materials have a significant gel content and a much lower MFT than the starting polymers, which should improve the creep resistance, provide higher tensile strength at break and provide materials that are harder than non-crosslinked polymer-blends. The end product has elastic properties (i.e., elongation at break of greater than 400%), but can be melt processed with methods normally known in the art for thermoplastics. The preferred gel content of the final product (i.e., rubber content) is between 10 to 50 wt%, most preferably 25-35 wt%. The tensile and flexible moduli in the machine and transverse directions are improved, as is the dart impact strength of the material. The TPVs are paintable and have better oil resistance. The TPVs may be used in, e.g., adhesives and sealants, cable insulations, pipes, profiles, moulded parts.foamed parts, sheets etc. The aminosilane rubber phase modified polymer will tend to be more compatible with the thermoplastic polymer, providing for a stronger TPV. Examples All silanes used are set forth above, except for SILQUEST A- 186 (γ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane), SILQUEST A- 187 (γ-glycidoxypropyltrimethoxysilane) and SILQUEST A- 189 (γ-mercaptopropyltrimethoxysilane). Compounding equipment: Brabender Head 50 cm J having Banbury knives. Compounding parameters: Brabender Head at 190 °C / RPM 120. All precents are weight percents unless otherwise specified. Process I: Total amount of ingredients of formulation : 55 g All ingredients were fed into the Brabender Head with the exception of homopolymer polypropylene VALTEC HL003 (+ 5 % Silane). After 5 min (Brabender torque value was noted) the VALTEC HL003 (+5 % Silane) was added into the Brabender Head. Time and value of the maximum Brabender torque was noted as an indicator for crosslinking. After the Brabender torque had dropped back to the initial level and homogenization of the compound is achieved (ca. 10 min), the compound was recovered from the Brabender. A specimen, 1.5 mm thickness, was molded in a press at 210 °C / 20 bars. Process LI: Same procedure as Process I but all ingredients were fed into the Brabender head at the same time. Compounding time 15min. A specimen, 1.5 mm thickness, was molded in a press at 210 °C / 100 bars for 200s. Examples 1-3 are given to show that a wide range of properties can be obtained, depending on the polymer grades. The weight percents given tor mateπal earned on another mateπal are based on the weight of the earner and earned mateπal. Example 1: Composition: 75% ENGAGE 8452 Ultra low density polyethylene (from Dupont Dow Elastomers, Melt Index (190 °C./ 2.16 kg): 3 g / 10 min; Density: 0.875 g/cc), 17% VALTEC HL003 polypropylene homopolymer (SPHERLPOL® porous granules from Montell: Melt Index (230 °C / 2.16 kg): 0.7 g / 10 mm; Density: 0.900 g cc), 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP (2.5-Dιmethyl 2.5-dι (tert-butylperoxy)hexane from Peroxid-Cherme, Munchen)), 2% VALTEC HL003 (+ 5 % soaked maleic anhydπde), 5% VALTEC HL003 (+ 5 % soaked A-1100), Process I. The maleic anhydnde was absorbed into the polymer by melting the anhydπde, (m.p. 53°C), blending it with the polymer and then cooling. Example 2: Composition: 75% NORDEL 2722 ethylene propylene diene monomer rubber (Dupont Dow Elastomers: Density: 0.88 g/cm 3 Mooney Viscosity ML 1+4 at 121 °C: 28), 17% VALTEC HL003, 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP), 2% VALTEC HL003 (+ 5 % soaked maleic anhydπde), 5% VALTEC HL003 (+ 5 % soaked A-1100), Process I. Example 3: Composition: 75% ENGAGE D8842.00 ultra low density polyethylene (from Dupont Dow Elastomers: Melt Index (190 °C / 2.16 kg) (1.0 g / 10 mm): Density: 0.857 g/cc), 17% VALTEC HL003, 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP), 2% VALTEC HL003 (+ 5 % soaked maleic anhydπde), 5% VALTEC HL003 (+ 5 % soaked A-1100), Process I Examples 4-7 illustrate influence of process and ingredients Example 4 (Comp.) Composition- 75% ENGAGE 8452. 25% VALTEC HL003, Process H Example 5 (Comp.): Composition: 75% ENGAGE 8452, 22% VALTEC HL003, 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP), 2% VALTEC HL003 (+ 5 % soaked maleic anhydride), Process I. Example 6 (Comp.): Composition: 75% ENGAGE 8452, 17% VALTEC HL003, 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP), 2% VALTEC HL003 (+ 5 % soaked maleic anhydride), 5% VALTEC HL003 (+ 5 % soaked A- 1100), Process II. Example 7 (Comp.): Composition: 75% ENGAGE 8452, 17% VALTEC HL003, 1% VALTEC HL003 (+ 5 % soaked INTEROX DHBP), 2% VALTEC HL003 (+ 5 % soaked maleic anhydride), 5% VALTEC HL003 (+ 5 % soaked hexadecyl amine). Process I. Examples 8-17 illustrate influence of silane type variation. Examples 15-17 are comparative. All silanes were added as a 5 weight-% masterbatch based on VALTEC HL003. Preparation of compounds was according to process I. PHYSICAL PROPERTIES The physical properties were measured according to the following norms: Elongation & Tensile at break ISO 37 (50mm/min) MR ISO 1872-1, No. 18 T SHORE A ISO 868 GEL CONTENT ISO 6427 Torque torquemeter on Brabender RESULTS VARIATION OF SLLANES Table 1 shows the properties of the materials obtained according to the procedures mentioned in the experimental part. The comparative examples (Comp. Ex.) consist of: Ex. 4) the pure blend of ENGAGE 8452 (PE) and VALTEC HL003 (PP): Ex. 5) blend of ENGAGE. VALTEC. peroxide and maleic anhydπde: Ex. 6) blend of ENGAGE, VALTEC, peroxide, maleic anhydride and A-1100, but everything mixed at once, and Ex. 7) blend of ENGAGE, VALTEC, peroxide, maleic anhydride and hexadecyl amine. Ex. 4 is to give the properties of the pure polymer blend. Ex. 5 to evaluate the influence of the silane alone, Ex. 6 to show the influence of the processing and Comp. Ex. 7 to prove the necessity of having a silane in the mixture. TABLE 1: Properties of the compounds Figure 1 displays the obtained gel contents for the different silanes, Fig. 2 shows the maximum torque observed dunng preparation of compounds. Data displayed in Figure 1 and 2 show that an increase in maximum torque observed dunng compounding is related to a crosslinking reaction. It is evident that all pπmary amines (SILQUEST A-1100, A-1110, A-1120, A-1130 and A-2120 silanes) induce a straight forward crosslinking, when being mixed into the polymer blend after gratting ot the maleic anhvdπde In contrary, mixing of all mateπals at the same time (Comp. Ex. 6) did not lead to any significant crosslinking The slight differences in degree ot crosslinking compared to A-1100 silane can be either due to different molar amounts, different number and/or kind of alkoxy group and number of am o functions per molecule. The mateπal obtained using the secondary amino silane A-1170 shows also a relatively high degree of crosslinking, whereas Y-9669 (secondary amino silane) causes no significant crosslinking. It is noted that since the molecular weight of A-1170 is considerably higher than the other silanes used, and the expeπments were run at equal silane weights, the molar amount of A-1170 is less than the other silanes and at equivalent molar amounts produces increased gel formation. The latter is also true both for the other silanes tested, as well as for the case where hexadecyl amine was employed instead of a silane. The data presented m Figures 3-5 show for all cases where crosslinking was observed a significant change in the matenal properties against the pure blend of the two polymers. The melt flow index drops to about 1/10, in the case of A-1110 silane even to 1/30. The mateπals are also significantly harder, have a higher tensile strength at break and a lower elongation at break. The changes in properties are consistent with the relative high degree of crosslinking these compounds. With respect to the other silanes employed, the properties of the resulting mateπals cannot be imputed to a high degree of crosslinking. However, all silanes causes a decrease of the MFI, indicating that some chain extension has occurred. This is evident in companng with all comparative examples and in particular with Comp Exp 5 (only peroxide and maleic anhydπde), where even a certain degree of degradation had taken place Note that a high MFI is measured also when A-1100 silane was mixed in at the same time as the other ingredients Exchanging the amino silane with hexadecyl amme (Comp. Ex. 7) leads also to a matenal with supeπor mechanical properties and higher hardness. The improvement of properties presumably is related to the attachment of long side chains to the polymer backbone ("comb polymers') since no crosslinking is possible. Thus, a TPV was not made (no gel content). Examples 18-21 - VARIATION OF AMLNOSLLANES The TPVs were prepared according to the procedure descπbed above. For all runs the amount of ammosilanes was kept the same (on a molar base). Silanes A and B are as follows- Silanes A, B and A-1170 gave products, which are slightly less yellow than the one obtained using A-1100. A-1170 as crosslinker leads to mateπals with very much improved adhesive properties, when compared to the other samples FOAM APPLICATION - Examples 22-25 The use of the TPV products for foam application was evaluated (Examples 22 and 23) and compared with formulations reacted only with peroxide and maleic anhydride only (Example 24) or peroxide (Example 25), respectively. The materials with exception of the blowing agent azodicarbonamide were reacted at 180°C in the Brabender (details for the preparation of TPVs as above). After 10 min the formulation was cooled down to 160°C and the blowing agent was added. In Example 23 the aminosilane was added after addition of the blowing agent. After further mixing for 3 minutes, test plaques were prepared at 170°C/100bar/100s. The plaques were foamed in an oven at 200°C for 3 to 5 minutes. Formulation as given below: Appearance of the foam structure The melt strength is high enough to support the decomposition temperatures of azodicarbonamide (200°C for several minutes). The shape remained within its original dimensions and does not stick on the support. In contrary, the non-crosslinked samples changed dimensions during foaming, thus leading to a worse cell structure and sticking to the support surface. The order of addition (silane before or after azodicarbonamide) seems not to influence significantly the appearance of the resulting foam or the amount of gel. Examples 26-29- Single Polymer TPVs The general procedure is the same as set forth above, however, in Examples 27-29, only one polymer was used, in Example 27 a polyethylene, in Example 28 HDPE LUPOLEN 503 IL by Elenac: . MFI (190°C, 2.16kg) = 6.5; Density: 0.952 and in Example 29, polypropylene. The system grafted maleic anhydride/aminosilane «an be used to crosslink pure ENGAGE resin as well as pure HDPE but did not lead to any gel when used in polypropylene.

Claims: We claim: 1. A composition comprising the reaction product of: a. a first polymer; b. a second polymer; c. carboxylic acid anhydride; and d. amino silane; wherein the acid anhydride is allowed to graft onto, or was copolymerized into one of the polymers prior to the addition of the amino silane and which composition has a gel content of between 10 to 50 wt%. 2. A composition according to claim 1 wherein the acid anhydride was grafted onto the polymer in the presence of a free radical generator. 3. A composition according to claim 1 wherein the acid anhydride is a comonomer in the first polymer. 4. A composition according to claim 1 wherein the aminosilane contains a primary amine. 5. A composition according to claim 1 wherein there are at least two different aminosilanes. 6. A composition according to claim 1 wherein there are at least two different acid anhydrides. 7. A process comprising: a. blending a first polymer, which is grafted with or copolymerized with a carboxylic acid anhydride, with a second polymer; and b. reacting the blend of step (a) with an aminosilane; and c. crosslinking the product of step (b). 8. A process according to claim 7 wherein the first polymer is grafted with an unsaturated carboxylic acid anhydride in the presence of a free radical generator. 9. A process according to claim 8 wherein the two polymers are blended prior to the grafting of the acid anhydride. 10. A process according to claim 7 wherein the first polymer is a copolymer of an unsaturated carboxylic acid anhydride. 11. A process according to claim 8 wherein the two polymers are blended after the first polymer is grafted with the acid anhydride. 12. A process according to claim 7 where the two polymers are reacted and blended in one step in one compounding extruder. 13. A process comprising: (a) adding an acid anhydride to a polymer; (b) heating the product of step (a) to melt the polymer; (c) adding an amino silane to the product of step (a); and (d) crosslinking the product of step (b).

Inventors: ABDERRAZIG ABDELLATIF, FURRER WILLY, KRAXNER PETER, SCHOMBOURG JACQUES F, ABDERRAZIG, ABDELLATIF, FURRER, WILLY, KRAXNER, PETER, SCHOMBOURG, JACQUES, F.
Applicants: ABDERRAZIG ABDELLATIF, FURRER WILLY, KRAXNER PETER, SCHOMBOURG JACQUES F, WITCO CORP, ABDERRAZIG, ABDELLATIF, FURRER, WILLY, KRAXNER, PETER, SCHOMBOURG, JACQUES, F., WITCO CORPORATION
Application year: 1999
Main classification: C08L23
IPC codes: C08F8, C08F291, C08K5, C08L23, C08L101