ETHYLENE VINYL SILANE COPOLYMER AND ITS PREPARATION

Abstract: For improving the mixability of two usually nonmixable polymers and for preventing a complete phase separation during handling, one polymer can be grafted on the other. In this invention is etherrified an ethylene vinyl silane polymer containing methoxy groups with another polymer containing hydroxy groups or with a monomer containing hydroxy groups. For example by blending the copolymer of styrene and hydroxy ethyl methacrylate with the terpolymer of ethyl butyl acrylate and vinyl trimethoxy silane, the copolymer is grafted with the silane terpolymer via etherification of the hydroxy groups and the methoxy groups. Alternatively, styrene and hydroxy ethyl methacrylate can be blended with a silane terpolymer by first etherifying the hydroxy groups of the methacrylate monomer and the methoxy groups of the terpolymer and by then copolymerizing styrene with hydroxy ethyl metacrylate. The resulting product is very homogenous and it can be used as compatibilizer and an adhesion plastic and as a polymer component in rubber bitumens.

Description: Ethylene vinyl silane copolymer and its preparation The invention relates to a grafted ethylene vinyl silane copolymer. Most copolymers are not compatible with each other. This is a problem, when a material is desired that has properties existing between the two starting polymers, or when a multilayer construction has to be prepared. The compatibility between two incompatible polymers can be increased at least in two ways. Firstly, a compatibilisizer may be incorporated. It can be a block copolymer (e.g. A-B or A-B-A), in which the blocks are comprised of the same monomers as the two homopolymers. The compatibilisizer can also be a grafted copolymer, in which the main polymer and the grafted polymer are the same as the two homopolymers. Secondly, one of the two copolymers to be joined to each other is prepared in the vicinity of the other polymer by means of a free radical polymerization technique, whereby the polymerizing monomer, from which the polymer is prepared, is grafted on the completed other polymer. This graft copolymer can then be used as such and formed into different articles or be used as a com¬ patibilisizer, as mentioned above. The grafting is generally performed by means of a free radical mechanism. A novel feature of this invention is that the grafting is achieved in a new way. This inventive grafted ethylene vinyl silane copolymer is mainly characterized in that it is an etherification product containing an ethylene vinyl silane copolymer and an organic polymer or a copolymer with hydroxy groups. The first embodiment of the method according to the invention is mainly characterized in that an ethylene vinyl silane copolymer is trans-etherified with a polymer or a copolymer containing hydroxy groups. The other embodiment of the method according to the invention is mainly characterized in that an ethylene vinyl silane copolymer is etherified with an unsaturated monomer containing one or more hydroxy groups, whereafter the hydroxy monomer is polymerized or alternatively copolymerized with other monomers containing one or more double bonds, whereby a large number of polymers can be grafted on the ethylene vinyl silane copolymer, whereby, the only requirement for the other monomers concerned is that they can be copoly- ■ merized with the hydroxy monomer. The preferred embodiments of the invention have the characteristics to be defined in the subclaims. In this invention, the grafting is also achieved by means of trans-etherification. According to the method, the grafting thus occurs by means of trans-etherificat- ion between the silane group in the polyethylene vinyl silane and some hydroxy monomer, in which case the hydroxy monomer can be grafted as such in the form of a monomer, after which it is polymerized and/or copolymerized with some other monomer containing double bonds. The hydroxy monomer can alternatively be polymerized and/or copolymerized before the grafting with some other monomer and the grafting of this polymer on the polyethylene vinyl silane is then performed in a molten state e.g. in an extruder. The graft copolymers according to this application can be used as such and formed into different articles or a compatibilisizer for incompatible polymers. Accordingly, there are two ways for making a graft copolymer according to the invention. However, both ways are based on the fact that the grafting itself occurs by means of trans-etherification between the silane group in the poly¬ ethylene silane and a hydroxy monomer. A large number of different polymers can be grafted by means of both methods. In principle, the only requirement for the fact that it is possible to graft a certain polymer on the polyethylene vinyl silane is that the monomers of the polymer concerned can be copolymerized with the hydroxy monomer, via which the grafting occurs. Useful polymer grades include ethylene polymers, in which the comonomer is a vinyl alkoxy silane compound, e.g. a vinyl trimetoxy silane or a vinyl triethoxy silane. In addition to ethylene and vinyl alkoxy silane, the ethylene copolymer can also include other such comonomers, which can be copolymerized with ethylene, e.g. α-olefines, such as propylene, butene or hexene, vinyl acetate, C,- -alkyl acrylates and C^ -alkyl methacrylates. The hydroxy monomer is a monomer with one or more double bonds and with one or more hydroxy groups. Suitable hydroxy monomers include e.g. hydroxy alkyl acrylates and methacrylates, allyl alcohol, acrylic and methacrylic acids. Said hydroxy monomers can be used as such or in mixtures with each other. The quantity of the hydroxy monomer of the entire quantity of monomers can be 0.01 - 100% by weight. The hydroxy monomer can be the only monomer, which is incorpoted into the polyethylene silane, but the hydroxy monomer can preferably be copolymerized with some other monomer. This monomer can be any monomer containing double bonds, which can be polymerized by means of a free radical polymerizat¬ ion technique. Examples of suitable monomers are aromatic vinyl monomers of type styrene and substituted styrenes, such as methyl styrene, isopropylene styrene and α-methyl styrene. Other suitable monomers include acrylonitrile and methacrylonitrile, C 1 -C 7 -alkyl acrylates and methacrylates, acrylic acids and methacrylic acids, vinyl halides, maleic acid anhydride, acrylic amide and methacrylic amide as well as α-olefines. The monomers can be used as such or in mixtures with each other or together with the hydroxy monomer. The quantity of the "other monomer" of the total quantity of the monomer can be 99.9 - 0 % by weight. The trans-etherification reaction between the hydroxy monomer and the alkoxy vinyl silane can in certain cases occur spontaneously at an elevated temperature. Catalysts can be added in small quantities for speeding up the reaction. As catalysts can be used e.g. alkali metal acetates, various acids, e.g. benzoic acid, as well as alkoxides of polyvalent elements M(OR) n , wherein M is preferably Al, Ti or Zr. It is evident for evebody well acquainted with polymer chemistry that grafted products according to the invention can also be achieved in such a way that the silane group and the hydroxy group change places so that the hydroxy group is contained in the ethylene copolymer and the silane group is contained in the other polymer. This method for synthesizing grafted products will not be described in more detail, but it is considered to be included within the scope of this invention, since the grafting occurs also in this case via a trans-etherification reaction between a hydroxy group and a silane group. Preparation method I In accordance with the method I, the hydroxy monomer is first grafted on silane and then polymerized. This can in practise be performed in many different ways. The polymerization can be performed in bulk or in a solution by dissolving the ethylene vinyl silane copolymer in the hydroxy monomer, the "other monomer" and eventually a solvent. By means of this method, the weight ratio between the ethylene vinyl silane copolymer and the grafted polymer can be varied within certain limits by adjusting the viscosity of the mixture with the quantity of the solvent. The polymerization can also be performed by means of a suspension technique. Also in this case the ethylene vinyl silane copolymer is dissolved in the hydroxy monomer and the "other monomer", but no solvent is present. After the grafting of the hydroxy monomer is completed, water and a suspension medium are added and the temperature is increased for polymerizing the monomers. In connection with this method, the maximum quantity of the ethylene vinyl silane copolymer in the final graft copolymer is ca. 30% by weight. A third way for preparing the graft copolymer according to the preparation method I is based on the fact that the ethylene vinyl silane copolymer is main¬ tained in a particle form during the polymerization. This facilitates the further handling of the material as well as washing and drying, and no pelletization of the product is needed. This preparation method is described below in detail. Ethylene vinyl silane copolymer particles, the hydroxy monomer and possibly some other monomer, an initiator and possibly a catalyst are mixed at room temperature or at an elevated temperature, but yet at so low a temperature that no polymerization occurs, whereby the particles are impregnated by the mono- mers, the catalyst and the initiators. During the impregnation, the particles swell to some extent, but they still maintain their particle structure. The impregnation is most preferably performed in the absence of water for preventing the ethylene vinyl silane copolymer from cross-linking with itself. The ratio between the quantity of the ethylene vinyl silane copolymer and the total quantity of the monomer can be 100 - 0.67. The impregnation can also be performed so that the total quantity of the hydroxy monomer but only part or no quantity of the "other monomer" is added before the impregnation phase. The remaining quantity of the "other monomer" is added after the water suspension has been prepared. The monomer can be added at the same time or in drops during several hours. The impregnation phase can be extended by using grafting instead of cross- linking so that the monomers, the catalyst and the initiators can be totally impregnated before water and the suspension medium are added. After the water suspension is completed, the temperature is increased, wereby the grafted hydroxy monomer as well as the free monomer are polymerized, after which grafted polymer chains are formed on the ethylene vinyl silane copolymer. When the polymerization is complete, the polymer particles are washed and dried. Such substances can be used as the suspension medium, which are conven¬ tionally used in connection with suspension polymerization of vinyl monomers. These include e.g. water soluble polymers, such as polyvinyl alcohol, polyvinyl pyrrolidone and methyl cellulose or partially water soluble substances, such as calcium triphostate and magnesium pyrophostate. The initiator has to be oil soluble, since the polymerization is performed by means of water suspension technique, and it has to have a half-time of 10 hours within a temperature range of 50-140°C. Initiators, which can be used for polymerizing the vinyl monomer, include organic peroxides, such as benzoyl peroxide, lauroyl peroxide, t-butyl perbenzoate, dikumyl peroxide as well azo compounds, such as azobisisobutyronitrile and azobisdimethyl valeronitrile. More than one initiator are preferably used simultaneously so that the polymerization is started at a low temperature with a low temperature initiator and completed at a high temperature with a high temperature initiator. The total quantity of the initiator can be 0.01 - 4 weight fractions and most preferably 0.1 - 0.2 weight fractions, based on 100 weights fractions of the monomer. In Fig. 1 is illustrated the preparation method I. As an example is here used an ethylene vinyl trimethoxy silane copolymer, which is grafted with hydroxy ethyl methacrylate during the release of methanol and after the subsequent copoly- merization with styrene. Preparation method II According to the preparation method π, the hydroxy monomer is first polymeriz¬ ed either as a homopolymer or a copolymer with one or more other monomers. This polymer is then admixed with an ethylene vinyl silane copolymer as well as a catalyst e.g. in an extruder, whereby the hydroxy monomer containing the polymer is grafted via a trans-etherification reaction. The advancement of the reaction is illustrated in Fig. 2, in which a copolymer of styren and hydroxy ethyl methacrylate is grafted on ethylene vinyl trimethoxy silane during the release of methanol. According to the method π, the grafting is thus achieved by blending two polymers in an extruder. It is therefore not important, how the hydroxy mono¬ mer containing the polymer has been prepared, but the main point is that it has reactive hydroxy groups. The preparation method for the polymer containing the hydroxy monomer can be free radical polymerization in bulk, in a solution or suspension, depending on the monomers to be used. The two polymers can be blended in any ratio with respect to each other. In the method II, the two polymers can be made to react with each other by means of so-called reactive film coextrusion. In this case, a good adhesion is achieved between the two films without having to use an adhesive medium. Typical applications for these materials include their use as compabilitisizers, adhesive plaster or as a polymer component in rubber bitumen. The basic material can also be blended or impregnated with a foaming agent and foamed into elastic foam plasters. The polymer can be handled with known methods designed for thermoplaster, e.g. extrusion, injection moulding, press forming, film blowing, extrusion coating. Examples Example I, 1 A 2-liter reactor was filled with 100 weight fractions of Visico 1407 (a commer¬ cial ethylene butyl acrylate vinyl trimethoxy silane terpolymer) in a particle form, the particle diameter being 3-4 mm, 36 weight fractions of styrene, 4.9 weight fractions of hydroxy ethyl methacrylate as well as 0.14 weight fractions of ben¬ zoyl peroxide as an initiator. This mixture was agitated slowly, 60 rpm, tead the temperature was increased to 75°C and was maintained there for three hours to allow the monomers and the initiator to diffuse in the Visico particles and to allow the hydroxy ethylene methacrylate to graft on the Visico polymer chains. After completed impregranation, a water suspension was prepared by adding 435 weight fractions (882 g) of water and, as suspension media, 1.0 weight fractions of tricalciumphostate and 0.02 weight fractions of potassium dodecyl benzene sulphonate. The temperature was then increased to 90°C and the remaining quantity of styrene, 64 weight fractions, (the total quantity of styrene 100 weight fractions) containing 0.26 weight fractions of benzoyl peroxide and 0.67 weight fractions of tert-butyl perbenzoate were added in drops during 4.5 hours. The polymerization was completed at 125°C for 4 hours. The polymerization product was in the form of separate homogenous particles. Example I, 2 This example was realized according to Example I, 1, except that also 0.01 weight fractions of benzoic acid were added as a catalyst with the first batch of the monomer for the grafting reaction. Example I, 3 This example was realized according to Example I, 1 and Example I, 2, except that the quantity of benzoic acid was 0.21 weight fractions. Example I, 4 This example was realized according to Example I, 1, except that 1.0 weight fractions of titan tert-butoxide was added as a catalyst with the first batch of the monomer and that the quantity of hydroxy ethyl metacrylate was 10 weight fractions. Example I, 5 Table 1 lists the results of extraction tests and DSC runs of products of Examp¬ les I, 1 - 1, 4. The table shows that the share of insoluble matter increases when the catalyst concentration increases at the same time as the share of Visico in the insoluble gel decreases, which indicates that the grafting has occurred. Table 1. Extraction and DSC runs of products of Examples I, 1 - 1, 4. 1, 2 0.01 - 42 51 1, 3 0.21 - 56 44 1, 4 - 1.0 61 38 1) a = benzoic acid, % by weight 2) b = titan tert-butoxide, % by weight 3) gel concentration determined in cooking xylene, extraction time 20 hours Example II, 1 A 2-liter reactor was filled with 100 weight fractions of styrene, 5.4 weight fractions of hydroxy ethyl methacrylate, 246 weight fractions of water (980 g), as well as as initiators,with 0.63 weight fractions of benzoyl peroxide and 0.21 weight fractions of tert-butyl perbenzoate. The polymerization was realized by means of a suspension technique in a conventional polystyrene related manner, and gelatine and bentonite were used as suspension media. The polymerization was performed at 95°C and 135°C during altogether 8 hours. The molar weight of the product was M w 110000 and dispersity 2.8. Example II, 2 5 weight fractions of the styrene hydroxy ethyl methacrylate copolymer prepared in Example II, 1 as well as 95 weight fractions of Visico 1407 were mixed in an extruder at 200°C for 10 minutes and then pressed into sheets with a thickness of 100 μm. The extraction of the product in methyl ethylene ketone indicated that 1-2% by weight were soluble, which shows that the styrene hydroxy ethyl metacrylate copolymer had partially grafted on the Visico polymer chains. Example II, 3 This Example was performed in accordance with Example II, 2 except that 0.3 weight fractions of benzoic acid were added as a catalyst during agitation in the extruder. The trans-etherification reaction between the hydroxy group in the hydroxy ethyl methacrylate styrene copolymer and the silane group in the Visico polymer is in this case more effective than in Example II, 2 and the share of soluble matter in methyl ethylene ketone < 1.0%. Example π, 4 This Example was performed in accordance with Example II, 2 except that 0.3 weight fractions of trinonyl phenyl phosphite were added as a catalyst during agitation in the extruder. When this material was stretched by 500% and then allowed to shrink, the remaining stretch was 400%, which indicates that the material has elastomeric properties.

Claims: Claims 1. A grafted ethylene vinyl silane copolymer, characterized in that it is an etherification product containing an ethylene vinyl silane copolymer and a grafted organic polymer or copolymer with hydroxy groups. 2. A polymer according to Claim 1, characterized in that the vinyl silane in the ethylene vinyl silane copolymer is a vinyl alkoxy silane compound, e.g. a vinyl trimetoxy silane or a vinyl triethoxy silane and that the ethylene vinyl silane copolymer can include as other comonomers e.g. α-olefines, vinyl acetate, C,- -alkyl acrylates and - -alkyl methacrylates. 3. A polymer according to Claim 1, characterized in that the hydroxy monomer of said organic polymer, which has one or more double bonds and one or more hydroxy groups and contains 1-10 carbon atoms, is e.g. a hydroxy alkyl acrylate or methacrylate, an allyl alcohol, or an acrylic or methacrylic acid. 4. A polymer according to any of the Claims 1-3, characterized in that said organic polymer is a copolymer, which can, in addition to monomers containing hydroxy groups, contain one or some of the following monomers: styrene, methyl styrene, acrylonitrile, - -alkyl acrylates and methacrylates, maleic acid anhydride, acrylic acids and methacrylic acids, α-olefines. 5. A polymer according to any of the Claim 1-4, characterized in that said organic copolymer is to contain 0.01-100% by weight of the hydroxy monomer. 6. A polymer according to any of the Claims 1-5, characterized in that the weight ratio between the ethylene vinyl silane copolymer and the grafted polymer can be, depending on the preparation method, 0 - ∞. 7. A method for preparing a grafted ethylene vinyl silane copolymer, characte¬ rized in that the ethylene vinyl silane copolymer is trans-etherified with a polymer or a copolymer containing hydroxy groups. 8. A method according to Claim 7, characterized in that the etherification is performed in a molten state e.g. in an extruder or at the end of an extruder e.g. in connection with a reactive film coextrusion. 9. A method according to Claims 7-8, characterized in that the trans-etherificat¬ ion can be speeded up by adding catalysts, e.g. alkali metal acetates, benzoic acid, as well as alkoxides of polyvalent elements M(OR) n , wherein M is prefer¬ ably a metal, e.g. titan. 10. A method according to any of the Claims 7-9, characterized in that the hydroxy monomer of said organic polymer has one or more double bonds and one or more hydroxy groups and contains 1-10 carbon atoms, and is e.g. a hydroxy alkyl acrylate or methacrylate, an allyl alcohol, or an acrylic or metha¬ crylic acid. 11. A method according to any of the Claims 7-10, characterized in that said organic polymer is a copolymer, which can, in addition to monomers containing hydroxy groups, contain one or some of the following monomers: styrene, methyl styrene, acrylonitrile, - -alkyl acrylates and methacrylates, maleic acid anhydride, acrylic acids and methacrylic acids, α-olefines. 12. A method according to any of the Claim 7-11, characterized in that said organic copolymer is to contain 0.01-100% by weight of the hydroxy monomer. 13. A polymer according to any of the Claims 7-12, characterized in that the share of the ethylene vinyl silane copolymer in the final grafted polymer is in the range 0 - oo. 14. A method for preparing a grafted ethylene vinyl silane copolymer, mainly characterized in that the ethylene vinyl silane copolymer is etherified with an unsaturated graftable monomer containing one or more hydroxy groups, wherea¬ fter the hydroxy monomer is polymerized or alternatively copolymerized with other monomers containing one or more double bonds, whereby a large number of polymers can be grafted on the ethylene vinyl silane copolymer, whereby the only requirement for the other monomers concerned is that they can be copoly¬ merized with the hydroxy monomer. 15. A method according to Claim 14,characterized in that the etherification is performed in bulk, a solution or suspension. 16. A method according to Claims 14-15,characterized in that the trans-etherifi¬ cation can be speeded up by adding catalysts, e.g. alkali metal acetates, benzoic acid, as well as alkoxides of polyvalent elements M(OR) π , wherein M is prefer- ably a metal, e.g. titan. 17. A method according to Claims 14-16,characterized in that after the etherific¬ ation with the ethylene vinyl silane copolymer, the hydroxy monomer is polymer¬ ized or copolymerized by means of a free radical polymerization technique. 18. A method according to any of the Claim 7-17, characterized in that the vinyl silane in the ethylene vinyl silane copolymer is a vinyl alkoxy silane compound, e.g. a vinyl trimetoxy silane or a vinyl triethoxy silane and that the ethylene vinyl silane copolymer can include as other comonomers e.g. α-olefines, vinyl acetate, Cr -alkyl acrylates and - -alkyl methacrylates. 19. A method according to Claims 14-18, characterized in that the hydroxy monomer has one or more double bonds and one or more hydroxy groups and contains 1-10 carbon atoms, and is e.g. a hydroxy alkyl acrylate or methacrylate, an allyl alcohol, or an acrylic or methacrylic acid. 20. A method according to any of the Claims 14-19, characterized in that said other monomers, which can be copolymerized with the hydroxy monomer, are styrene, methyl styrene, acrylonitrile, C^ -alkyl acrylates and methacrylates, maleic acid anhydride, acrylic acids and methacrylic acids, α-olefines. 21. A method according to any of the Claim 14-20, characterized in that the mutual quantities between the other monomer and the hydroxy monomer are totally 0.01-100% by weight of the hydroxy monomer. 22. A method according to any of the Claims 14-21, characterized in that the weight ratio between the ethylene vinyl silane copolymer and the grafted polymer can be 0 - oo. 23. A grafted ethylene copolymer, characterized in that it is a trans-etherifica¬ tion product of an ethylene copolymer containing hydroxy groups and another polymer containing silane groups. 24. Utilization of the product according to any of the Claims 1-6 and 23 as a compabilitisizer, adhesion plastic, polymer component in rubber bitumen or for foaming into elastic foam plastic.

Inventors: BERGSTROEM CHRISTER, LEHTINIEMI ISMO, PUROPAASI MARKKU, VESTBERG TORVALD, BERGSTROEM, CHRISTER, LEHTINIEMI, ISMO, PUROPAASI, MARKKU, VESTBERG, TORVALD
Applicants: NESTE OY
Application year: 1991
Main classification: C08F291
IPC codes: C08F290, C08F299