WO1995023183A1

WO1995023183A1 - Liquid crystalline polymer blends and processes for the preparation thereof

Info

Publication number: WO1995023183A1
Application number: PCT/FI1995/000116
Authority: WO
Inventors: Riitta Holsti-Miettinen; Olli Ikkala
Original assignee: Neste Oy
Priority date: 1994-02-28
Filing date: 1995-02-28
Publication date: 1995-08-31

Abstract

The present invention concerns liquid crystalline polymer blends, a process for the preparation thereof as well as products manufactured from the blends. The blends according to the invention contain some 95 to 5 parts by weight of a matrix polymer and about 5 to 50 parts by weight of a liquid crystalline polymer. In addition they also contain, based on the total weight of the previous components, 0.1 to 10 percent by weight of an organometallic compound, preferably a neoalkoxy titanate or neoalkoxy zirconate compound. The organometallic compound improves the stiffness of the blends such that the tensile and flexural moduli of the blends are up to 30 % better than the corresponding properties of blends which do not contain said organometallic compound.

Description

LIQUID CRYSTALLINE POLYMER BLENDS AND PROCESSES FOR THE PREPARATION THEREOF

Field of the invention

The present invention relates to liquid crystalline polymer blends in accordance with the preamble of claim 1.

Such blends typically contain about 95 to about 5 parts by weight of a matrix polymer and 5 to 50 parts by weight of a liquid crystalline polymer.

The invention also relates to a process for the preparation of the polymer blends, to a method for increasing the stiffness of liquid crystalline polymer blends, as well as to products at least partially consisting of a blend according to the invention.

Description of the prior art

Liquid crystalline polymers (LCP's) are polymers which in melt state lie between the boundaries of solid crystals and isotropic liquids. The liquid crystalline structure is called an anisotropic phase because macroscopically in the melt state the LCP's are fluids.

Blends of liquid crystalline polymers and other polymers, in particular thermoplastics, are known in the art. One of the aims of blending LCP's with other polymers is to improve the strength of the other polymer component of the blend, which normally makes up the matrix of the polymer blend. Said aim is achieved if the liquid crystalline polymer forms fibers which orientate in the flow direction of the thermoplastic matrix melt. As a result, there can then be an improvement of the mechanical properties, such as tensile strength and modulus of elasticity, of the thermoplastic in this direction. The addition of the liquid crystalline polymer can also improve the heat durability of the thermoplastics and dimensional stability and enhances their processability.

In practice, however, the above situation does not readily arise, in particular for nonpolar polymer matrices formed by, for instance, polyolefins (PO's) . Therefore, the mechanical properties of LCP/PO blends usually lag far behind the predicted values, and special additives and processing techniques are called for.

Production of high-strength LCP/thermoplastic blends requires, as mentioned, processing of the liquid crystalline polymer in such a way that it forms long fibers within the blend. There should also be good interfacial adhesion between the polymer blend components in order to achieve maximum increase of strength. However, although liquid crystalline polymers are not that difficult to process as neat compounds, it is, in practice, difficult to process liquid crystalline polymers into fibrous structures in blends with thermoplastic polymers because of their anisotropic behaviour. The stiffness of LCP/thermoplastic blends is therefore often rather poor as is the interfacial adhesion between the components, which is evidenced by a decrease in impact strength caused by the addition of a liquid crystalline polymer into a thermoplastic matrix.

Summary of the invention

It is, therefore, an object of the present invention to remove the problems relating to the prior art and to provide liquid crystalline polymer blends of an entirely novel kind.

The present invention is based on the concept of increasing the stiffness of liquid crystalline polymer blends by melt blending the LCP and the thermoplastic components with at least one organometallic titanate or zirconate of the general formula I

R,-C(-R) (-R₂) -CH₂-0-M(-A)_a(-B)_b(-C)_c (I) wherein

M is zirconium or titanium,

R, R, and R₂ are each a monovalent alkyl, alkenyl, alkynyl, aralkyl, aryl or alkaryl group having up to 20 carbon atoms, or a halogen or ether substituted derivative thereof, and, in addition, R₂ may also be an oxy derivative or an ether substituted oxy derivative of said groups; A, B and C are each a monovalent aroxy, thioaroxy, diester phosphate, diester pyrophosphate, oxyalkylamino, sulfonyl or carboxyl; and a, b and c are each integers in the range of 0 to 3, and the sum of a, b and c equals 3.

The tensile and flexural moduli of LCP/thermoplastic polymer blends containing some 0.1 to 10 wt-% of the organometallic compounds (the amount of said compound being calculated on basis of the total weight of the LCP and the thermoplastic components) are at least 5 %, preferably at least 10 % and in particularly at least 30 % better than the corresponding properties of blends which do not contain said organometallic compounds.

The blends may contain several organometallic compounds of the above formula I, and they may also contain reactive compatibilizers.

In particular, the blend according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.

The process according to the invention is characterized by what is stated in the characterizing part of claim 13.

The method for increasing the stiffness of LCP blends is characterized by what is stated in the characterizing part of claim 16. Brief description of the drawings

The present invention is described in greater detail with reference to the accompanying drawings, of which

Figure 1 depicts the tensile modulus of extruded strands of

PP/LCP blends as a function of draw ratio,

Figure 2 depicts the tensile modulus of extruded strands of

HDPE/LCP blends as a function of draw ratio, and

Figures 3a to 3c depict SEM micrographs of fractional surfaces of PP/LCP blends containing 0, 0.5 and 1 wt-% of a neoalkoxy- titanate according to the invention.

Detailed description of the invention

Definitions

According to the present invention the "stiffness" of the polymer blends is characterized by the tensile modulus which is determined according to ISO/R527. Another measure of polymer stiffness is the flexural modulus, which is determined according to ISO/178.

The term "isotropic polymer" designates any thermoplastic polymer which does not decompose below its melting point and which therefore can be melt processed. The term "matrix polymer" is also used for said thermoplastic polymer, indicating that in at least most of the blends, the isotropic polymer forms the continuous phase, in which the LCP's are embedded forming reinforcing fibers. As will be apparent from the below description, as thermoplastic polymers polar polymers as well as — and preferably — nonpolar polymers can be used. As examples of the latter cathegory, the polyolefins should specifically be mentioned.

The terms "anisotropic polymers" or "liquid crystalline polymers (LCP's) " are interchangeably used for polymers which in liquid state, in particular as a melt (= thermotropic LCP's) , lie between the boundaries of solid crystals and isotropic liquids.

Within the scope of the present invention, the mixtures of two or more (neat) polymers, if desired mixed with suitable additives and adjuvants, are called "blends". This term also includes polymer blends typically containing additives and adjuvants, which have been processed into a homogeneous mixture, which can be used for the manufacture of the polymer product, for instance a film or a sheet.

For the purpose of this description the term "compatibilizer" means a substance which promotes the compatibility of the isotropic and anisotropic components of the compounds .

"Organic titanates" and "organic zirconates" denote the organometallic compounds of general formula I above.

"Reactive compatibilizer containing functional groups" covers polymers which are capable of reacting with at least one of the components of the blend. In practice it is difficult to determine the exact nature of the interaction between the compatibilizer and the other components of the blend, and to ascertain whether a chemical reaction has taken place or not. Therefore, within the scope of the present application, all polymers which contain functional groups capable of reacting with the functional groups of the matrix polymer and/or the liquid crystalline polymer, are considered to be reactive compatibilizers.

Polymer blend composition

As mentioned above, the polymer blends are comprised of isotropic and anisotropic polymers which together form a polymer blend. According to the present invention polymer blends are prepared, in which the amount of the liquid crystalline polymer lies in the range from about 5 to about 50 percent by weight, in particular about 10 to about 40 percent by weight of the total amount of the matrix polymer and the liquid crystalline polymer. The corresponding amount of the matrix polymer is preferably about 95 to about 50 percent by weight, in particular about 90 to about 60 percent by weight. The amount of the organometallic compound is in the range of about 0.01 to 5 percent by weight (of the blend) , in particular about 0.1 to 3 percent by weight (based on the total weight of the isotropic and anisotropic polymers) . The amount of the compatibilizer can vary in the range of about 0.1 to 30 percent, preferably it is about 1 to 15 percent by weight (based on the total weight of the isotropic and anisotropic polymers) . These relative amounts of the components will provide a reinforced plastic, in which the reinforcement is comprised of the liquid crystalline polymer.

In addition to the above components, the blend can, of course, contain additives and adjuvents known per se.

Polymer blend components

The organic titanates and zirconates used in the present invention have previously been employed as coupling agents. They have also been suggested for use as polymer modifiers for improving extrusion and molding producting rates as well as for use as polymer blend modifiers [Monte, S.J. and Sugerman, G.,

The use of organometallic titanates and zirconates as reactants and compatibilizers in polymers, Compalloy '90, March 1990, New Orleans, U.S.A.] . It is proposed in the prior art that some of these compounds react with substrate surface protones at the inorganic interface resulting in the formation of matrix/reactive organic monomolecular layers on the inorganic surface according to a alcoholysis mechanism. In addition to alcoholysis, titanates provide transesterification and trans- alkylation catalysis . Zirconates exhibit similar properties as the titanates, but they have better color and UV stability.

There is, however, no suggestion in the prior art that organic titanates and organic zirconates could be used in blends composed of liquid crystalline polymers and isotropic polymers, as disclosed in the present invention, and, particularly, that the addition of these compounds would enhance the formation of the LCP fibers under drawing, resulting in an improvement of the stiffness of the LCP blends. In this connection it can be noted that the tensile modulus of the present polymer blend is at least 5 %, preferably at least about 10 %, and most preferably at least 30 % better than that of a corresponding blend which does not contain any organometallic compound. In the case of polyolefin-based LCP-blends, such as PP/LCP or HDPE/LCP -blends, the tensile modulus is typically over 3,000 MPa, i.e. at least about 300 to 500 MPa better than the corresponding values of blends which do not containing the present titanates of zirconates. These features will be described in more detail in connection with the examples below.

We have not been able to ascertain the mechanism behind the interaction of the organic titanates or zirconates and the components of LCP blends, but it is possible that, if the LCP used has hydroxyl end groups, alcoholysis type reactions may occur. If there are epoxy group or other functional groups in the blend, they may act as catalyzers of these reactions.

In the general formula I, Ar (in "aroxy", for instance) may be a monovalent aryl or alkaryl group having 6 to 20 carbon atoms, optionally containing up to 3 optionally substituted ether oxygen substituents.

Preferably the groups R, j and R₂ are alkyl having 1 to 8 carbon atoms (metyl, propyl, cyclohexyl, 2,4-dimethoxybenzyl, 1-methyl- 4-acenaphthyl-2-ethyl-2-furyl) , aralkyl having 6 to 10 carbon atoms (such as benzene) , the aryl and alkaryl groups having from 6 to 10 carbons atoms including phenyl, naphtyl, tolyl, zylyl, and the halogen substituted bromophenyl, and the allyloxy- substituted alkyl having from 4 to 20 carbon atoms and the allyloxy-substituted aryl having from 9 to 20 carbon atoms. Where R₂ is an oxy derivative, the most preferred compounds are the alkoxy derivatives having from 1 to 3 carbon atoms and the phenoxy group.

A, B and C are preferably aryl or thioaryl ligands, such as phenoxy, 2, 4-dimethyl-l-naphthoxy, 3-octyl-l-phenanthroxy and 3, 5-diethyl-2-thioanthryl and 2-methyl-3-methoxy thiophenylas well as diester phosphates such as dibutyl, methylphenyl, lauryl etc. as well as aryl sulfonyl groups such as phenylsulfonyl and 2-methyl-3-ethyl-4-phenanthryl sulfonyl.

Particularly preferred are carboxyl groups such as methacryl, stearyl, 4-phenyoxy and acetyl.

The organometallic compounds according to the general formula I can, for instance, be selected from the group comprising organometallic titanates and organometallic zirconates having the general formula II

ROMXYZ (II)

wherein

RO is an alkoxy group capable of reacting with surface protons, M is a metal (Ti or Zr) ,

X represents carboxylate or alkoholate linkage

Y is an alkyl or aryl functional group, and

Z stands for reactive amino, thio, or acrylic groups.

The RO groups are preferably monoalkoxy groups, such as alkanolato groups (for instance 2-propanolato) or, in particular, neoalkoxy groups, such as alkenolatoalkyl groups (for instance bis 2-propenolatomethyl) .

As specific examples of preferred titanates and zirconates, the following can be mentioned:

- neopentyl (diallyl) oxy, tri (dioxtyl)phosphato titanate; - neopentyl (diallyl) oxy, tri (N-ethylenediamino) ethyl titanate; and

- neopentyl (diallyl) oxy, tri (dioctyl)phosphato zirconate.

As mentioned above, in case of blends composed of LCP's and isotropic polymers, it is important to improve interfacial adhesion in order to achieve proper enforcement of the matrix polymer. It is known in the art that the compatibility of liquid crystalline polymers and thermoplastics and the impact strength of blends thereof can be improved by adding to the blends a third component, i.e. a substance known as a compatibilizer. In particular, as described in our International Patent Application No. WO 93/24574, by adding polymers containing reactive groups it is possible to provide polymer blends whose draw strength and bending strength is better than the corresponding properties of the polymer matrix at the same time as the impact strength remains at least fairly good as far as practical embodiments are concerned. The impact strengths of the polymer blends are at least 20 % better than the impacts strenghts of corresponding uncompatibilized blends.

Thus, when compatibilizers are used in the compounds according to the invention, they typically consist of reactive compatibilizer whose functional groups comprise, for example, carboxy, anhydride, epoxy, oxazolino, hydroxy, isocyanate, acylacetam and carbodiimide groups. The polymer residues of the compatibilizer can comprise co- and terpolymers, grafted polyolefins, grafted polystyrene and thermoplastic elastomers. The polar groups of polyolefinic copolymers are generally acrylic esters, functional acrylic acid groups, and maleic anhydride groups. The polar groups of the terpolymers can be maleic anhydride groups, hydroxyl groups and epoxy groups, of which the first-mentioned are particularly preferred. The styrene block copolymers can consist of polystyrene segments and flexible elastomer segments. Typical styrene block copolymers are SBS (styrene/butadiene/styrene-copolymer) , SIS (styrene/isoprene/styrene-copolymer) and SEBS (styrene/ethylene butylene/styrene-copolymer) .

The liquid crystalline polymer of the blend may, for instance, comprise an aromatic main chain thermotropic polymer, preferably a thermotropic polyester, poly (ester amide) , poly (ester ether) , poly(ester carbonate) or poly(ester imide) . It can also comprise a copolymer of a polyester, such as a copolymer of poly(ethylene terephthalate) and hydroxy benzoic acid or a copolymer of hydroxynaphthoic acid and hydroxybenzoic acid.

Generally, the liquid crystalline polymer, which is used in the present invention, can be defined as a polymer which is formed when the components of the following general formulas (or at least two of them) are reacted with each other: a dicarboxylic acid of formula III

HOOC-R₃-COOH (III)

a diol of formula IV

HO-R₄-OH (IV)

a hydroxycarboxylic acid of formula V

HO-R₅-COOH (V)

wherein

R₃, R₄, and R₅ each independently represents a bivalent aromatic hydrocarbon group, a group of formula R₆-X-R₇, wherein R₆ and R₇ represent a bivalent hydrocarbon group and X is an oxygen or a sulphur atom, a sulphonyl, carbonyl, alkylene, or ester group or X is a single bond, a xylylene group or a bivalent aliphatic hydrocarbon group.

The liquid crystalline polymer can also comprise a homopolymer of a hydroxycarboxylic acid of formula VI

HO-R₅- COOH (VI ) .

Typically, the aromatic dicarboxylic acids of formula I are selected from the group comprising terephthalic acid, isophthalic acid, 4,4'diphenyl-dicarboxylic acid, diphenyl ether-4,4' -dicarboxylic acid, diphenylethane-3, 3' -dicarboxylic acid, diphenylethane-4,4' -dicarboxylic acid, diphenyl ether- -3,3' -dicarboxylic acid, 4,4' -triphenyl-dicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, diphenoxyethane- 4,4' -dicarboxylic acid, diphenoxybutane-4,4' -dicarboxylic acid, diphenoxyethane-3,3' -dicarboxylic acid, and naphthalene- -1, 6-dicarboxylic acid.

Said aromatic dicarboxylic acids may be alkyl-, alkoxy-, or halogen-substituted. The substituted derivatives can be selected from the group comprising chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, and ethoxyterephthalic acid

The alicyclic dicarboxylic acids of formula III can be selected from the group comprising trans-1,4-cyclohexanedicarboxylic acid, cis-1,4-cyclo-hexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid.

The alicyclic dicarboxylic acids may also be substituted by one or more alkyl-, alkoxy-, or halogen-substituent (s) . The substituted dicarboxylic acid derivatives can be selected from the group comprising trans-1,4- (1-methyl) -cyclohexane- dicarboxylic acid and trans-1,4- (1-chloro) cyclohexane- dicarboxylic acid.

The aromatic diols of formula IV can be selected from the group comprising hydroquinone, resorcinol, 4,4' -dihydroxydiphenyl, 4-4' -dihydroxytriphenyl, 1, 6-naphthalenediol, 2, 6-naphalene- diol, 4,4' -dihydroxydiphenyl ether, 3,3' -dihydroxydiphenyl, 1, 1-bis (4-hydroxyphenyl) -methane, bis (4-hydroxyphenoxy) -ethane, 2,2-bis ( -hydroxyphenyl)propane, and 3 , 3' -dihydroxy-diphenyl ether. These diols may be substituted by one or more alkyl-, alkoxy-, or halogen substituent (s) , which derivatives are exemplified by the following list: chlorohydroquinone, methylhydroquinone, 1-butylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4-chlororesorcinol, and methylresorcinol.

Typical examples of alicyclic diols of formula IV include trans- and cis-1,4-cyclohexanediols, trans-1,4-cyclohexane-dimethanol, trans-1, 3-cyclohexanediol, cis-1,2-cyclohexanediol, and trans-1, 3-cyclohexanedimethanol. Instead of these compounds the corresponding alkyl-, alkoxy-, or halogen-substituted derivatives can be used, as well.

The aliphatic diols of formula IV can be straight-chained or branched and selected from the group comprising ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyl glycol. The aromatic hydroxycarboxylic acids of formula III are selected from the group comprising 4-hydroxybenzoic acid, 3- hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 6-hydroxy-l-naphthoic acid. These compounds can be alkyl-, alkoxy-, or halogen-substituted. The substituted aromatic hydroxycarboxylic acid derivatives are preferably selected from the group comprising 3-methyl-4-hydroxybenzoic acid, 3, 5-dimethyl- -hydroxybenzoic acid, 2, 6-dimethyl- -4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3, 5-dimethoxy-4-hydroxybenzoic acid, 6-hydroxy-5-methyl- 2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid, 3-chloro-4-hydroxybenzoic acid, 2, 3-dichloro-4-hydroxybenzoic acid, 3, 5-dichloro-hydroxybenzoic acid, 2, 5-dichloro- -4-hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid, 6- hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro- -2-naphthoic acid, and 6-hydroxy-5, 7-dichloro-2-naphthoic acid. In addition to the above mentioned polyesters, the LCP's used in the monolayer structures according to the invention can comprise the corresponding polyester amides. It is also possible to use polymers having a main chain containing conjugated double bonds, the monomer units of said main chain being linked to unsubstituted or substituted side chains which, together with the main chain render the polymer liquid-crystal properties. Examples of such polymers are polytiophene, polyaniline, polyacetylene, polypyrrole and polyparaphenylene substituted with alkyl chains containing at least 8 carbon atoms.

The following liquid crystalline polymers are particularly preferred:

copolyesters of terephthalic acid, alkylhydroquinone, p- hydroxybenzoic acid and poly(alkylene terephthalate) , the alkylene substituent preferably comprising ethylene or butylene and the alkyl substituent of the hydroquinone preferably comprising a lower alkyl group such as propyl or (tertiary) butyl,

copolyesters of p-hydroxybenzoic acid and poly(alkylene terephthalate) , the alkylene group preferably being ethylene or butylene,

copolyesters of terephthalic acid, alkylhydroquinone, p- hydroxybenzoic acid and hydroxyalkylphenyl-alkanoic acids, the alkyl-substituent of the hydroquinone preferably comprising a lower alkyl group such as propyl or (tertiary) butyl, the alkanoic acid preferably containing 3 to 8 carbon atoms, propanoic acid being particularly preferred, and

blockcopolyesters of trimellithic imide-terminated poly(THF) or polysilicone, containing the imide group in para- or meta- position i.e. N- (4-carboxy-phenyl) -trimellit imide or N-(3'- acetoxy-phenyl) -trimellit imide, with acetoxybenzoic acid and at least one repeating unit selected from the group comprising diacetoxy diphenyl, hydroquinone diacetate, terephthalic acid, a trimer designated HBA-HQ-HBA (the synthesis of which is described in Europ. Polym. J. 20, 3, 225-235 (1984) , and poly(ethylene terephthalate) (PET) .

According to the invention, it is particularly preferred to use liquid crystalline polymers having as high chain linearity as possible. These kinds of LCP's are particularly well suited for use as barrier components in blends with thermotropic polymers.

The molecular weight of the liquid crystal polymer used in the present invention depends on the character of the repeating units of the LCP. Usually, the molecular weight is in the range of about 1,000 to 300,000. If fully aromatic polyesters are used as LCP's, their molecular weight is typically in the range of about 2,000 to 200,000, preferably about 10,000 to 50,000.

More general details on liquid crystalline polymers and their properties and applications are given in an article titled "Liquid Crystal Polymers and Their Applications" by Chung et al. in Handbook of Polymer Science and Technology, Vol. 2 (1989) 625 - 675.

The isotropic polymer of the monolayer structure can comprise any suitable polymer material which has the desired properties regarding resistance to penetration of water vapor as well as regarding strength and processability.

As examples of the isotropic polymers, the following may be mentioned: polyolefins such as polyethylene, polypropylene, polybutylene, polyisobutylene, poly(4-methyl-1-pentylene) , including copolymers of ethylene and propylene (EPM, EPDM) and chlorinated (PVC) and chlorosulphonated polyethylenes. The isotropic polymer may also be comprised of the corresponding polyalkanes, which contain styrene (PS), acryl, vinyl and fluoroethylene groups, and different polyesters, such as poly(ethylene terephthalate) , poly(butylene terephthalate) and polycarbonate, polyamides and polyethers (e.g. poly(phenylene ether) : Particularly preferred polymers are the polyolefins and polyesters.

The molecular weights of the preferred isotropic thermoplastic polymers are usually in a range from about 5,000 to 50,000, preferably about 10,000 to 30,000.

Of the polymer blend additives, fillers, pigments and various substances which promote the processing o the blend can be mentioned.

Plastic additives known per se can be added to the polymer blend according to the invention. These additives comprise, for instance, stabilizers, colouring agents, lubricants, antistatic agents, fillers and fire retardants. If desired, these substances can be premixed with, e.g., the isotropic polymer before forming the polymer blend. The amounts of polymer additives are typically about 0.01 to 5 %, preferably about 0.1 to 10 % of the weight of the polymer blend.

Processing of the polymer blends

The thermoplastic/liquid crystalline polymer blends according to the invention can be prepared by methods known per se.

The mixing methods are either batch or continuous processes. As examples of typical batch mixers, the Banbury mixer and the heated roll mill may be mentioned. Continuous mixers are exemplified by, for instance, the Farrel mixer, and single- and double-screw extruders. Preferably single- or twin-screw extruders are used for blending the liquid crystalline polymer with the thermoplastic. The liquid crystalline polymers are blended with the thermoplastics either by first premixing the liquid crystalline polymers with the thermoplastics in a twin- screw extruder and then processing them in an injection moulding machine or, alternatively, by processing them by injection moulding or extrusion without premixing.

The blends according to the invention can be processed according to methods known per se in polymer technology to manufacture the final products. Thus, the blends can be used for preparing molded articles, extruded products and thermoformed products. The molded articles can be manufactured by, for instance, injection moulding or blow moulding. Fibres, films, pipes, profiles, cables, cable sheathings and coatings may be mentioned as examples of extruded products.

Because, as mentioned above, the liquid crystalline polymer blends are "in situ" blends it is particularly preferred to process the blends by extrusion, LCP fibres being formed during extrusion, which improves the strength properties of the products in longitudinal direction. According to a preferred embodiment of the invention, extrusion is used to manufacture liquid crystalline polymer blends consisting of a polyolefin matrix.

By using rotating dies or similar methods it is possible to achieve not only longitudinal reinforcement of products prepared by extrusion but also transversal reinforcement. The biaxial orientation thus obtained is particularly preferred when liquid crystalline polymer blends are used for manufacturing certain products.

Considerable advantages are achieved by the polymer blends according to the invention and by their use for various applications. Thus, in particular, the tensile and flexural moduli of LCP/thermoplastic polymer blends containing some 0.1 to 10 wt-% of the organometallic compound are even over 30 % better than the corresponding properties of blends which do not contain said organometallic compound. By using the organo¬ metallic compound(s) as described in this invention, it will now be possible to prepare blends of LCP's and nonpolar thermo- plastics, such as polyolefins, having good stiffness. Therefore, the blends according to the invention can be used as barrier materials as well as for instrument parts requiring dimensional stability. Due to a small temperature coefficient, the blends are also well suited for use as constructional materials.

With reference to what is stated above, the present invention concerns, in particular, pipes, tubes and films made from the blends typically have good barrier properties, i.e. low permeability. The invention also concerns structional parts manufactured from the above-mentioned liquid crystalline polymer blends and intended for use in the automotive industry.

The blends can also be used for manufacturing injection molded, blow molded and deep drawn products.

In the following, the invention and its benefits will be illustrated with the help of working examples describing the preparation of polyolefin/LCP blends.

Example 1

PP/LCP and HDPE/LCP blends were prepared in a Berstoff ZE 25x33 D twin screw extruder. The melt temperature was at 240 - 245 °C, and "Polyblends" screw configuration was used. Rotation speed was 200 rpm and feeding rate about 9 kg/hr. The LCP component was predried before melt blending for 5 hrs at 50 °C. The prepared blends were predried overnight at 80 °C before injection moulding_ Injection molded specimen were mechanically tested after 2 days of conditioning.

The materials used were the following:

- HDPE: NCPE 1515 supplied by Neste Oy, PP: VB 65 supplied by Neste Oy, - LCP: Rodrun LC-3000 (a copolyester of p-hydroxybenzoic acid and polyethyleneterephthalate, supplied by Unitika Ltd. ) , Zirconate: neopentyl (diallyl) oxy, tri (dioctyl)phosphato zirconate, supplied under the name CAPS NZ 12/L by

Kenrich Petrochemicals, Inc.

Titanate I: neopentyl (diallyl) oxy, tri (dioctyl)phosphato titanate, supplied under the name CAPS L 12/L by Kenrich

Petrochemicals, Inc.

Titanate II: neopentyl (diallyl) oxy, tri (N-ethylene- diamino) ethyl titanate, supplied under the anme CAPS L

44/E by Kenrich Petrochemicals, Inc.

Compatiblizer I: Lotader 8660 supplied by Norsolor and

Compatibilizer II: a MAH-grafted PP supplied under the name Exxelor 1015 by Exxon Chemicals.

The recipes of the blends are given in table 1.

Table 1. Recipes of pc >lyolefin/LCP blends

Sample # Isotropic LCP/wt-% Organometallic Compatibilizer/ polymer/wt-% compound/ t-% wt-%

1 PP/69 30 Zirconate/1 -

2 PP/69 30 Titanate 1/1 -

3 PP/69 30 Titanate II/l -

4 PP/70 30 - -

5 PP/69 30 - Comp. 1/1

6 PP/69 30 - Comp. II/l

7 PP/68 30 Titanate 1/1 Comp. 1/1

8 PP/68 30 Titanate 1/1 Comp. II/l

9 HDPE/69 30 Zirconate/l -

10 HDPE/69 30 Titanate 1/1 -

11 HDPE/69 30 Titanate II/l -

12 HDPE/70 30 - -

13 HDPE/70 30 - Comp. I/l

Part of the samples were tested for orientation under drawing. Blends were extruded in a single screw Brabender extruder and immediately quenched in a water bath and drawn at different speeds of the take-up machine to form strands of different diameter. The draw ratio for each strand was determined as the ration between the die and strand sections. The dimensions of the round hole capillary die were: length 30 mm and diameter 5 mm. The screw speed was kept at 100 rpm for all blends. The strands were tensile tested. The diameter of the rods was uneven but it was evaluated as an average of at least five measurements.

Results of mechanical and thermal testing are shown in Table 2.

Table 2. Mechanical and thermal properties of LCP/PO blends

Sample Tensile Tensile Tens. Strain Tensile Flexural

# Modulus Stress at at Break (%) Strength Modulus (MPa) Break (MPa) (MPa) (MPa)

1 3260 39.7 2.5 39.8 3230

2 3030 37.7 2.6 37.7 3070

3 2680 34.5 2.4 34.7 2940

4 2900 36.8 2.7 37.0 2860

5 2930 38.0 2.7 38.1 2910

6 3070 37.8 2.4 38.0 2930

7 3010 38.1 2.6 38.5 3020

8 3150 38.6 2.5 39.0 3080

9 2810 38.3 2.8 38.4 2740

10 3060 38.7 2.5 38.8 2990

11 2780 36.9 2.7 36.9 2750

12 2560 36.8 3.1 36.9 2520

13 2450 36.1 3.2 36.2 2460

It is apparent from the results indicated in Table 2 that the addition of neoalkoxy zirconates improves the tensile modulus of both LCP/HDPE and LCP/PP blends. The improvement with neoalkoxy titanates was more pronounced in HDPE/LCP blends that in PP/LCP blends. It is worthwhile noticing that the mechanical strength of blend sample 8, which contained both a titanate and a compatibilizer (Exxelor 1015) , was better than that of Reference Sample No. 4. This combination of modifiers also gave the best impact strength.

Tensile properties of extruded blends as a function of draw ratio are given in Table 3 and depicted in Figures 1 and 2.

Table 3. Results of tensile testing of extruded strands

Sample # Tensile Strength Elastic Module (MPa) (MPa)

1 draw ratio 2 34.9 1607

4 39.2 1964 6 38.1 2430 8 37.5 2441 10 51.3 3547

2 draw ratio 2 35.3 1631

4 33.2 2030 6 38.2 2649 8 48.7 3719 10 44.0 3637

4 draw ratio 2 32.7 1453

4 45.4 2462 6 30.3 1999 8 37.4 2697 10

5 draw ratio 2 36.6 1595

4 34.5 1807 6 34.9 2339 * 8 36.9 2599 10

6 draw ratio 2 42.5 1764

4 30.7 1714 6 32.9 2132 8 40.8 2995 10

9 draw ratio 2 31.0 1263

4 36.8 1954 6 29.9 2090 8 45.3 3032 10

12 draw ratio 2 37.1 1407

4 35.2 1907 6 44.9 2240 8 34.0 2155 10

* poor extrudate quality

As the best references for the modulus behaviour of LCP/polyolefin blends, samples 4 and 12 were used, which contained 70 wt-% of PP and 30 wt-% of LCP, and 70 wt-% HDPE an 30 wt-% LCP, respectively. The dependence of tensile modulus on draw ratio can be explained by the ability of LCP molecules to orientate themselves in the direction of the melt flow during processing. In extrusion, the die and the belt capstan direct strong uniaxial elongational forces towards the molten material, which causes uniaxial orientation of the LCP molecules. As indicated by the data of Table 3, the tensile strength of extruded strands was improved with draw ratio only for those PP/LCP or HDPE/LCP blends, which contained titanate or zirconate modifiers. The deviation of results is due to inaccurancy at the determination of the cross sectional area of the uneven extrudates. Also the numerical value of the actual draw ratio is not accurate.

The tensile modulus increased for all blends with the draw ratio. However, Table 3 and Figures 1 and 2 clearly show that the improvement of stiffness with the draw ratio was most significant for blends, where there was 1 wt-% neoalkoxy titanate.

Example 2

The morphology of three blends was examined by SEM. Injection moulded samples were fractured in liquid nitrogen across the flow direction. The SEM micrographs are shown in Figures 3a, 3b and 3c. The sample depicted in Figure 3a contained 70 wt-% PP and 30 wt-% of an LCP (Rodrun 3000) , whereas the sample shown in Figure 3b contained 69.5 wt-% PP, 30 wt-% LCP and 0.5 % titanate I. Figure 3c shows the micrograph of a blend containing 69 wt-% PP, 30 wt-% LCP and 1 wt-% titanate II.

It is obvious that the morphology of the samples shown in Figures 3b and 3c is quite different from the morphology of the sample shown in Figure 3a; the addition of a titanate enhances LCP fiber orientation during extrusion giving rise to distinct fibers which increase the stiffness of the blends. Example 3

HDPE/LCP blends were prepared with Brabender DSK counter rotating twin screw extruder with L/D ratio 7 and screw diamete of 42 mm. The LCP used (Rodrun LC3000 by Unitika) comprised a copolymer of poly(ethylene terephthalate) and hydroxybenzoic acid having the composition (PET)_0.4- (PHB)₀₆. The HDPE was supplie by Neste (NCPE 7003) . The LCP was dried at 80 - 90 °C for 16 h before extrusion. The mixing temperature was 230 °C, the rotation speed 50 rpm and the residence time approximately 90 s. Before injection molding the blends were carefully dried at 80 °C for two days. Injection molding was performed by using Krauss Maffei 60-210B.

Injection molded test bars were tensile tested according to ISO/R527 and their temperature resistance was tested according to HDT/B ISO 75 and Vicat A ISO 306. The cross head speed was 1 mm/min for determination of the tensile modulus and 5 mm/min fo the other values.

Titanates and zirconates were used as organometallic compounds . The abbreviations are the same as in Example 1.

In all cases the LCP weight fraction was kept constant at 30 wt-%-.

Table 4. Tensile testing of extruded strands of HDPE/LCP blends

LCP HDPE Organometallic Tensile Tensile Tensile compound modulus stress, strain at σ break, e wt-% wt-% Type wt-% MPa MPa %

30 70 - 0 2350 33.7 3.0

30 69 Zirconate 1 3790 40.3 1.8

30 69 Titanate I 1 3780 30.9 1.9

30 69 Titanate II 1 3480 36.6 1.7 It is observed that, significant improvements are achieved in the stiffness of the HDPE blend, indicating improved compatibility.

Example 4

PP/LCP blends were prepared with Berstorff co rotating twin screw extruder as in Example 1. The LCP used (Rodrun LC3000 by Unitika) comprises a copolymer of poly(ethylene terephthalate) and hydroxybenzoic acid having the composition (PET)₀₄- (PHB)₀₆. The PP was supplied by Neste Oy (VB 65) . Injection molding and mechanical testing were performed as in Example 3.

Titanate CAPS L 12/L was used as organometallic compound, as in Example 1.

In all cases the LCP weight fraction was kept constant at 30 wt-%.

Table 5. Tensile testing of extruded strands of PP/LCP blends

LCP PP Organometallic Tensile Tensile compound modulus stress, σ wt-% wt-% Type wt-% MPa MPa

30 70 - 0 2840 36.0

30 69.5 Titanate I 0.5 3030 36.2

30 69 Titanate I 1 3180 36.5

Claims

Claims :

1. A polymer blend containing

95 to 5 parts by weight of a matrix polymer, and - 5 to 50 parts by weight of a liquid crystalline polymer, c h a r a c t e r i z e d in that

- the blend further contains 0.1 to 10 per cent by weight of an organometallic compound of the general formula I

R,-C(-R) (-R₂)-CH₂-0-M(-A)_a(-B)_b(-C)_c (I)

wherein

M is zirconium or titanium,

R, R_j and R₂ are each a monovalent alkyl, alkenyl, alkynyl, aralkyl, aryl or alkaryl group having up to 20 carbon atoms, or a halogen or ether substituted derivative thereof, and, in addition, R₂ may also be an oxy derivative or an ether substituted oxy derivative of said groups;

A, B and C are each a monovalent aroxy, thioaroxy, diester phosphate, diester pyrophosphate, oxyalkylamino, sulfonyl or carboxyl; and a, b and c are each integers in the range of 0 to 3 and the sum of a, b and c equals 3, and the tensile and flexural moduli of the blend are at least 5 % better than the corresponding properties of blends which do not contain said organometallic compound.

2. The blend according to claim 1, wherein the organometallic compound is selected from the group comprising neoalkoxy triorganofunctional titanates and neoalkoxy triorgano-functional zirconates.

3. The blend according to claim 1 or 2, wherein the blend contains about 0.1 to 2 per cent by weight of the organometallic compound .

4. The blend according to claim 1, which further comprises 0.1 to 30 percent by weight of a substance (compatibilizer) promoting the compatibility of the polymer matrix and the liquid crystalline component, said substance consisting of a polymer containing reactive functional groups.

5. The blend according to claim 4, wherein the compatibilizer is selected from the group comprising co- or terpolymers containing reactive epoxy groups, co- or terpolymer containing maleic anhydride groups, and functionalized elastomers.

6. The polymer blend according to claim 1, wherein the amount of the liquid crystalline polymer is about 10 to about 40 percent by weight of the total amount of the matrix polymer and the liquid crystalline polymer.

7. The polymer blend according to any of the previous claims, wherein the matrix polymer comprises polyolefins, in particular polypropylene or polyethylene or copolymers thereof, or a polyester, in particular poly(ethylene terephthalate or poly(butylene terephthalate) .

8. The polymer blend according to any of claims 1 to 7, wherein the liquid crystalline polymer is a polymer, which is formed when the components of the following general formulas (or at least two of them) are reacted with each other: a dicarboxylic acid of formula H0QC-R₃-C00H, a diol of formula H0-R₄-0H, and a oxycarboxylic acid of formula H0-R₅-C00H, wherein R₃, R₄ and R₅ represent a bivalent aromatic hydrocarbon group, a group of formula R₆-X-R₇, wherein R₆ and R₇ represent a bivalent hydrocarbon group and X is an oxygen or a sulphur atom, a sulphonyl, carbonyl, alkylene, or ester group or X is a single bond, a xylylene group or a bivalent aliphatic hydrocarbon group.

9. The polymer blend according to claim 8, wherein the liquid crystalline polymer comprises an aromatic copolyester.

10. The polymer blend according to any of the previous claims, wherein the LCP component comprises a copolyester of p-hydroxy- benzoic acid (PHB) and poly(ethylene terephthalate) (PET) or an aromatic copolyester of tert-butylhydrokinone (t-BuHQ) , terephthalic acid (T) , hydroxybenzoic acid (HBA) , and poly(ethylene terephthalate) (PET), such as t-BuHQ25/T25/- HBA35/PET15, and the polymer matrix comprises polypropylene or polyethylene.

11. The polymer blend according to claim 1, wherein the bleid contains - about 60 to about 75 parts by weight of polypropylene

(PP) or polyethylene (PE) , - about 25 to about 40 parts by weight of a liquid crystalline polymer (LCP) comprising a copolymer of poly(ethylene terephthalate) and hydroxybenzoic acid, and

0.1 to 2 parts by weight of an organometallic compound selected from the grup comprising neoalkoxy titanate and neoalkoxy zirconate, the tensile modulus being greater than 3000 MPa measured according to ISO/R527.

12. The polymer blend according to any one of the previous claims, wherein the tensile modulus is increased by at least 200 MPa.

13. A process for preparing a polymer blend, c h a r a c t e r i z e d by melt mixing

95 to 5 parts by weight of a thermoplastic polymer, 5 to 50 parts by weight of a liquid crystalline polymer, and

0.1 to 10 per cent by weight of an organometallic compound of the general formula I Rι-C(-R) (-R₂) -CH₂-0-M(-A)_a(-B)_b(-C)_c (I)

wherein

M is zirconium or titanium, R, R_j and R₂ are each a monovalent alkyl, alkenyl, alkynyl, aralkyl, aryl or alkaryl group having up to 20 carbon atoms, or a halogen or ether substituted derivative thereof, and, in addition, R₂ may also be an oxy derivative or an ether substituted oxy derivative of said groups; A, B and C are each a monovalent aroxy, thioaroxy, diester phosphate, diester pyrophosphate, oxyalkylamino, sulfonyl or carboxyl; and a, b and c are each integers in the range of 0 to 3 and the sum of a, b and c equals 3, in order to form a polymer blend, whose tensile and flexural moduli are at least 5 % better than the corresponding properties of blends which does not contain said organometallic compound.

14. The process according to claim 13 , wherein the polymer blend is extruded in order to increase the orientation of the liquid crystalline polymer component.

15. The process according to claim 14, wherein extrusion is carried out by using rotary dies or equivalent means.

16. A method for increasing the stiffness of polymer blends containing 95 to 5 parts by weight of thermoplastic polymer, and 5 to 50 parts by weight of a liquid crystalline polymer, c h a r a c t e r i z e d in that 0.1 to 10 % (calculated on basis of the weight of the polymer blend) of an organo-metallic compound selected from the group comprising neoalkoxy titanates and neoalkoxy zirconates is added to the mixture of the thermoplastic polymer and the liquid crystalline polymer, and the mixture is compounded by melt-blending under conditions of increased draw ratios.

17. Injection molded, blow molded and deep drawn products, c h a r a c t e r i z e d in that they consist at least partially of a blend according to any one of claims 1 to 12.

18. Pipes, tubes and films, c h a r a c t e r i z e d in that they consist at least partially of a blend according to any one of claims 1 to 12.

19. Constructional parts for the automotive industry, c h a r a c t e r i z e d in that they consist at least partially of a blend according to any one of claims 1 to 12.