CS216652B2 - Thermoplastic forming substance - Google Patents

Abstract

1382472 Polyoxymethylene compositions HOECHST AG 17 Jan 1972 [15 Jan 1971 7 Oct 1971] 2235/72 Heading C3P A moulding composition comprises 99À999- 90% of a linear polyoxymethylene and 0À001-10% by wt. of a branched or cross-linked polyoxymethylene. The components, each optionally containing a stabilizer, may be mixed in powder form then melted, homogenized, extruded and granulated. The linear polymer may be a homopolymer of formaldehyde or trioxan or a copolymer of trioxan with a monofunctional comonomer such as a cyclic ether, cyclic acetal or linear polyacetal: exemplified comonomers are ethylene oxide and 1,3- dioxolane. The branched or cross-linked polymer may be prepared (a) by copolymerizing trioxan with a polyfunctional comonomer and optionally a monofunctional comonomer: copolymers of trioxan with ethylene oxide or dioxolane and dicyclopentadiene oxide, methyl glycidyl formal, 1,4-butanediol diglycidyl ether, 1,2,6-hexanertiol formal, or oligomeric formals of 1,2,6-hexanetriol and 1,6-hexanediol or polyethylene glycol are exemplified; (b) by crosslinking a copolymer of trioxas, a polyfunctional monomer of which only one functionality is copolymerizable and optionally a monofunctional comonomer such as ethylene oxide or dioxolane by means appropriate to the residual function(s) of the polyfunctional monomer; in the examples copolymers in which the latter is p-glycidoxybenzaldehyde are cross-linked by reaction with hydrazine, adipic acid bishydrazide or ethylene diamine or by heating, a copolymer of methyl p-glycidoxycinnamate is cross-linked by U.V. irradiation, and copolymers of p-glycidoxynitrobenzene or epichlorohydrin are cross-linked by reaction with 4,41-diisocyanatodiphenylmethane after conversion of the nitro and chloro groups to amino and hydroxy respectively; (c) by polymerizing trioxan and optionally a monofunctional comonomer in the presence of a branched or cross-linked polyether, or by reacting a linear polyoxymethylene with such a polyether, in the examples trioxan and dioxolane are copolymerized in the presence of polyethers derived from tetrahydrofuran, ethylene glycol and 1,4-butanediol diglycidyl ether or 2,9-dioxa-dispiro [3.2.3.2] duodecane, and a trioxan-dioxolane copolymer is reacted with 1,4-butanediol diglycidyl ether in the presence of BF 3 .Bu 2 O. Either of the polymer components may be treated, e.g. by heating with an alcohol in the presence of an amine, to remove unstable end-groups.

Description

(54) Thermoplastic molding compound

The present invention relates to a polyoxymethylene-based thermoplastic molding composition containing in addition to 99.999 to 90. % of linear polyoxymethylene 0.001 to 10% by weight of a branching or crosslinked polyoxymethylene nucleating agent.

The present invention relates to a thermoplastic molding composition based on polyoxymethylene.

It is known that polyacetals (polyoxymethylenes POM) have a strong tendency to crystallize. Even with a small undercooling of their melt, the spherulites, which are often much larger than the wavelength of light, give a considerable opacity to the material. In addition, as a result of the crystallization process, rich, microscopic cracks and internal stresses arise inside and on the surface of the material. These cracks and internal stresses adversely affect the mechanical properties of the polyoxymethylene shaped bodies, for example injection molded parts. The aforementioned defects are the more pronounced the greater the individual spherulites.

It is further known that by adding 0.0001 to 0.5% by weight of talc to high molecular weight polyoxymethylenes and uniformly dispersing this inorganic additive in the organic material, the crystalline structure of the injection molded articles can be unified, starting from a coarse spherulite structure with mean spherulite diameters. 100 μτη to homogeneous structures with a spherulite diameter of 4 to 8 µm (cf. British Patent Specification 1133 490), since these are injection molded specimens, the sizes given refer to products which crystallize under pressure at temperatures between 80 and 100 degrees Celsius. .

It is further known that the size of polyoxymethylene spherulites can be reduced when polyoxymethylenes are mixed with certain organic nucleating agents which are not soluble or only slightly soluble in the melt of the polyoxymethylenes, for example with imidazole or pyrazine derivatives containing hydroxyl groups before melting (cf. British Patent Specification 1 193 708).

In addition, it is known that the crystalline structure of thermoplastic, crystallizable high polymers, for example oxymethylene polymers, can be modified by cooling the polymer melt using nucleating agents that are chemically stable at temperatures above the crystallization temperature of the polymer melt (cf. U.S. Patent 3,367,926). In addition to a large number of different chemical compounds, polyoxymethylenes are also mentioned as nucleating agents, but there is no indication as to whether polyoxymethylenes are suitable as nucleating agents for other polyoxymethylenes. However, when the known linear homo- or copolymers of formaldehyde or trioxane (the formaldehyde trimer, trioxymethylene) are nucleated by addition of the same or another linear formaldehyde or trioxane homo- or copolymer, the nucleation effect is never achieved.

The present invention relates to thermoplastic molding compositions which consist of a mixture

99.999 to 90% by weight of linear polyoxymethylene and 0.001 to 10% by weight of branched or crosslinked polyoxymethylene.

The linear polyoxymethylenes used in the molding compositions according to the invention are obtained by known methods and are homopolymers of formaldehyde or trioxane or copolymers of trioxane and at least one copolymerizable, monofunctional reacting compound.

The branched or crosslinked polyoxymethylenes used according to the invention can be obtained

(a) copolymerization of trioxane with at least one trioxane copolymerizable, multifunctional reacting compound and optionally with at least one trioxane copolymerizable, monofunctional reacting compound, bj via branching or crosslinking reactions, additionally performed on linear or chain functional polyoxymethylene, or

c) coplymerizing the trioxane with at least one, trioxane copolymerizable, monofunctional reacting compound with a branched or crosslinked polyether, optionally by reacting a linear polyoxymethylene with a branched or crosslinked polyether.

The proportion of linear polyoxymethylene in the molding compositions according to the invention is preferably 99.99 to 95% by weight, while the proportion of branched or crosslinked polyoxymethylene according to a) and b) is preferably between 0.01 and 5% by weight. Molding compositions consisting of 99.9 to 98% by weight of a linear polymer and 0.1 to 2% by weight of a branched or crosslinked polymer according to a) and b) show particularly good properties.

The molding compositions according to the invention p. The branched or crosslinked polyoxymethylenes according to c) preferably contain 99.9 to 95% by weight of linear polyoxymethylene and 0.1 to 5% by weight of branched or crosslinked polyoxymethylene. The molding compositions according to the invention with branched or crosslinked polyoxymethylene according to the invention exhibit particularly good properties

c) containing from 99.5 to 97% by weight of linear polyoxymethylene and from 0.5 to 3% by weight of branched or crosslinked polyoxymethylene.

For branched or crosslinked polyoxymethylenes with a low melt index, generally less than satisfactory nucleation is sufficient for polyoxymethylenes with a higher melt index.

Formaldehyde or trioxane homopolymers are those formaldehyde or trioxane homopolymers whose terminal hydroxyl groups are chemically stabilized against cleavage, for example by esterification or etherification.

When using linear trioxane copolymers 161652, the trioxane comonomers are cyclic ethers having 3 to 5, preferably 3 ring members and different cyclic acetals with 5 to 11, preferably 5 to 8 ring members and linear polyacetals, in each case 0 in trioxane. %, 1 to 20, preferably 0.5 to 10% by weight. Copolymers of 99 to 95% by weight of trioxane and 1 to 5% by weight of one of the components are most suitable.

Compounds of formula I are used as cyclic ethers and cyclic acetals

-O

I_____J (i) in which

R 1 and R 2 are the same or different and each represents a hydrogen atom, an aliphatic alkyl radical having 1 to 6, preferably 1 to 3 carbon atoms, which may contain 1 to 3 halogen atoms, preferably chlorine, or denotes a phenyl radical,

X is either an integer from 1 to 3 and y is zero or x is zero, y is an integer from 1 to 3 and z equals 2, or x is equal to zero, y is 1 and z is an integer from 3 to 6, preferably 3 or 4 or in which

R 1 represents an alkoxymethyl radical having 2 to 6, preferably 2 to 4 carbon atoms or a phenoxymethyl radical, where x equals 1 and y equals zero and

R2 is as previously defined.

Particularly suitable as cyclic ethers and cyclic acetals are compounds of formula II

I-1 _(II) in which

R represents a hydrogen atom, an aliphatic alkyl radical having 1 to 6, preferably 1 to 3 carbon atoms, which may contain 1 to 3 halogen atoms, preferably chlorine, or - denotes a phenyl radical, x being either an integer from 1 to 3 and y equals zero or x equals zero, y is an integer from 1 to 3 and z equals 2 or x equals zero, y is 1 and z is an integer from 3 to 6, preferably 3 or 4, or wherein

R @ 2 denotes an alkoxymethyl radical having from 2 to 3 carbon atoms;

Or preferably denotes a phenoxymethyl radical, wherein x equals 1 and y equals zero.

Preferably, compounds of formula III are used as cyclic ethers and cyclic acetals.

L ——----—-- 1 au) wherein x is either an integer from 1 to 3 and y equals zero, -or x is equal to zero, y is an integer from 1 to 3 and z is equal to 2, or wherein x is zero, y is 1 and z is an integer of 3 to 6, preferably 3 or 4.

Particularly suitable cyclic ethers are those having 3 ring members, for example ethylene oxide, styrene oxide, propylene oxide and epichlorohydrin and phenylglycidyl ether.

Particularly suitable cyclic acetals are cyclic aliphatic or cycloaliphatic-α, ω-diols having 2 to 8, preferably 2 to 4 carbon atoms, the carbon chain of which may be interrupted by an oxygen atom at 2 carbon atoms, for example glycolformal (1,3- butanediolformal (1,3-dioxopropane) and diglycolformal (1,3,6-trioxocanone, such as 4-chloromethyl-1,3-dioxolane and hexanediolformal (1,3-dioxonanone);

Suitable linear polyacetals are both homopolymers or copolymers of previously defined cyclic acetals as well as linear condensates of aliphatic or cycloaliphatic-α, ω-diols with aliphatic aldehydes or thioaldehydes, preferably with formaldehyde. In particular, homopolymers of linear aliphatic-α, ω-diols having 2 to 8, preferably 2 to 4 carbon atoms, are used, for example polydioxolane, poly- (1,3-propanediolformal) and poly- (1,4-butanediolformal).

The values for reduced specific viscosity (RSV values) of the linear polyoxymethylenes used according to the invention (measured in butyrolactone containing 2% by weight diphenylamine) at 140 ° C at a concentration of 0.5 g / 100 ml are between 0.07 and 2.50 dl.g ^_1, preferably between 0.14 and 1.20 dg ^-1. crystallite melting points of the polyoxymethylenes are in the range from 140 to 180 ° C and their density is between 1.38 and 1.45 g.ml-1 (measured according to DIN 53,479).

The linear, preferably binary or ternary trioxane copolymers used according to the invention are prepared in a known manner by polymerizing the monomers in the presence of cationically active catalysts at temperatures between 0 and 100 ° C, preferably between 50 and 90 ° C (cf., for example, British Patent 903,668). . Lewis acids, for example boron trifluoride and antimony fluoride and complex compounds of Lewis acids, preferably ethers, for example boron trifluoride diethyl etherate and boron trifluoride di-tert-butyl etherate, are used as catalysts. Protonic acids such as perchloric acid and salt type compounds such as triphenylmethylhexafluorophosphate, triethyloxanium tetrafluoroborate - or acetylperchlorate are also suitable. The polymerization can be. in a mass, suspension or solution.

To remove unstable fractions, the copolymers are expediently subjected to thermal or hydrolytic controlled, partial degradation down to the primary alcohol groups (cf., for example, British Patent Specifications 924 903, 951 272 and 986 925).

The formaldehyde or trioxane homopolymers used according to the invention are also produced in a known manner by catalytic monomer polymerization (cf., for example, U.S. Patent 2,768,994 and British Patent 877,820).

In the production of the branched or crosslinked polyoxymethyl dreams according to a) by copolymerization of trioxane with at least one, a trioxane copolymerizable, a multifunctional reacting compound and optionally with at least one s-trioxane monofunctional reacting compound, the multifunctional compounds are generally used in an amount of 0.01 to 5. preferably 0.05 to 2% by weight, and the monofunctional compounds are generally used in an amount of 0.1 to -10%, preferably 1 to -5% by weight.

The monofunctional reacting compounds used are the cyclic ethers, cyclic acetals and linear polyacetals mentioned in the preparation of the - linear trioxane - copolymers used according to the invention.

Monomeric or oligomeric compounds which contain one of the aforementioned monofunctional cyclic ether or cyclic acetal groups and do not contain any or contain one or more linear acetal groups, the total number of said reactive compounds being used as multifunctional reacting compounds. however, the cyclic ether, cyclic acetal and linear acetal groups are at least 2. Preferably, alkyl glycidylformals, polyglycol diglycidyl ethers, alkanediol diglycidyl ethers and bis (alkanetriol) -trifolds are used.

Alkylglycidylformals are understood to mean compounds of formula IV

R-O-CH, -O-CH ° (IV) in which

R represents an aliphatic alkyl radical having 1 to 10, preferably 1 to 5, carbon atoms.

Particularly suitable are the alkylglycidylformals of the above formula wherein R is a linear, low, aliphatic alkyl radical, for example methylglycidylformal, ethylglycidylformal, propylglycidylformal - and butylglycidylformal.

Polyglycol diglycidyl ethers are compounds of formula V

in which n is an integer from 2 to 5. Particularly suitable are polyglycol diglycyl ether ethers of the preceding formula - in which n is - 2 or 3, for example diethylene glycol diglycidyl ether and tri ethylene glycol diglycidyl ether.

The alkanediol diglycidyl ethers are compounds of formula VI

_R CH CH CH _£ O- (CH? O-CH-CH-CH, o \ o ⁷ wherein Under bis- (alkantriol) Ormala-Trifluoro means

............ ................. .............. compounds with one linear and two cycles . represents an integer from 2 to 6, preferably 2, format groups, in particular up to 4, of the compound of formula VII

Butanediol diglycidyl ether is particularly suitable.

- О-CK-O- (СнЛ _г CH-ch, f> i Ί] I ^r oo \ /

CH, o \ /

CH is one in which paq is always an integer from 3 to 9, preferably 3 or 4. Symmetrical bis (alkanetriol) -triformals of the preceding formula are particularly suitable, in which paq denotes the same number, for example bis (1,2,5-pentanetriol) -triformal and preferably bis (1,2,6-hexanetriol) -trifluoral.

Oligomeric forms obtained by reacting 1 mole of 1,2 (5-11) -triol with 0 to 1 mole of α, ω-diol having a molecular weight of 62 can also be used as multifunctional reacting compounds for the production of branched or crosslinked polyoxymethylenes used according to the invention. up to 1000, 0 to 1 mole of monovalent alcohol having 1 to 11 carbon atoms and 1 mole of formaldehyde for each 2 moles of OH groups of the reaction mixture (cf. British Patent Specification 1171107).

The copolymerization of the trioxane with said multifunctional and monofunctional compounds is carried out in the manner already described for the production of linear trioxane copolymers. Cleavage of the unstable chain ends can in principle be carried out according to methods known for stabilizing the end groups of trioxane copolymers. However, it is also possible to use branched or crosslinked polyoxymethylenes in finely ground form as nucleating agent directly without further processing.

A further possibility of making these branched or crosslinked polyoxymethylenes is to react the linear polyoxymethylenes with the above-mentioned multifunctional compounds using cationic catalysts and preferably using inert diluents such as cyclohexane, n-hexane or methylene chloride.

The branched or crosslinked polyoxymethylenes b) used according to the invention are obtained by intermolecular reaction of linear polyoxymethylenes with side or chain functional groups, optionally after chemical conversion of these groups into other functional groups and optionally in the presence of bifunctional crosslinking agents.

The aforementioned polyoxymethylenes having side or chain functional groups are produced by polymerizing with a mixture of 99.9 to 60, preferably 99.7 to 80% by weight trioxane, 0 to 20, preferably 0.1 to 10% by weight, cyclic ether having 3 to 5 ring members or from a trioxane different cyclic acetal having 5 to 11 ring members or a linear polyacetal and 0.1 to 20, preferably 0.2 to 10% by weight of at least one trioxane copolymerizable, multifunctional compound. Particularly good results are obtained when 1-5% by weight of monofunctional and 1-5% by weight of the multifunctional compounds are used.

For the production of linear, polyoxymethylene-containing functional groups, monomeric compounds are used as multifunctional compounds which, on the one hand, contain one functional group reacting under polymerization conditions and, on the other hand, contain at least one functional group which does not react under polymerization conditions. Particularly suitable for this purpose are saturated cyclic ethers or acetals with aromatic or aliphatic substituents which themselves carry at least one such unreacting functional group, or at least simply unsaturated cyclic ethers or acetals. Preference is given to using aldehyde, hydroxy, nitro or ester groups or epoxy compounds containing halogen atoms, for example o-, in- and p-glycidoxybenzaldehyde, 3-methyl-4-glycidoxybenzaldehyde, 3-methoxy-4-glycidoxybenzaldehyde, p-glycidoxynitrobenzene 2,4-dinitro-1-glycidoxybenzene, 1,6-dinitro-2-glycidoxynaphthalene, p-glycidoxybenzoic acid methyl ester, epoxymethacrylic acid methyl ester, p-glycidoxycinnamic acid methyl ester and epichlorohydrin. As unsaturated cyclic acetals, in particular, simple unsaturated cyclic forms having more than 6, preferably 7 and 8 ring members, such as 1,3-dioxacycloheptene (5) or cyclic forms with unstable ring double bonds and 5 to 11, preferably 5, are used. up to 8 ring members, such as

4-vinyldioxolane-1,3 and 5-vinyl-1,3-dioxa-cyclohexane.

As unsaturated cyclic ethers, cyclic ethers having 3 to 5 ring members and one unstable ring double bond are used, for example butanediene monoxide, dicyclopentadiene monoxide and vinylcyclohexene oxide (1-vinyl-3,4-epoxycyclohexane).

The polymerization is carried out in a known manner by polymerizing monomers in the presence of cationically active catalysts, at temperatures between 0 and 100 ° C, preferably between 50 and 90 ° C (see also, for example, British Patent Specifications 1,146,649, 1,179,260, 1,179,576, 1,031 705 and 1 039 936] The cleavage of the unstable chain ends can be carried out in principle by known methods for stabilizing the end groups of trioxane copolymers.

Conversion of linear polyoxymethylenes with side or chain functional groups into branched or crosslinked polyoxymethylenes is carried out, optionally after chemical conversion of the functional groups, either by direct functional reaction of the functional groups or by reaction with bifunctional crosslinking agents. The conversion is carried out in solution, in suspension or preferably in the melt. Suitable solvents are inert polar solvents, for example benzyl alcohol, chlorobenzene, dimethylformamide and β-butyrolactone. Suitable aliphatic, cycloaliphatic or aromatic hydrocarbons having 6 to 18 carbon atoms, for example hexane, cyclohexane and toluene, are suitable suspending agents.

Crosslinking is carried out at temperatures between and 230 ° C. In solutions, the temperature is preferably between 110 and 170 ° C, in the suspension between 50 and 170 degrees Celsius and in the melt between 150 and 230 ° C.

Photochemically induced reactions are also suitable [cf. British Patent Specifications 936 176 and 1 155 863):

The polyoxymethylenes containing aldehyde groups are preferably coupled together by condensation with blunctionally effective crosslinking agents, in particular hydrazine, terephthalic acid dihydrazide, semicarbazide, dicyandiamide, urea, thiourea, thioacetamide, ammonia, acetone, aliphatic diamines, and aromatic diamine diamines, for example, and aromatic diamines, for example 4,4'-diisocyanatodiphenylmethane (cf., for example, British Patent Specification '1 156 045). Optionally, the presence of basic catalysts, for example piperidine, is expedient.

Polyoxymethylenes with side nitro groups are. first, they are converted by known methods to polyoxymethylenes with lateral amino groups. Combining these amino groups with suitable bifunctional agents such as dialdehydes. (e.g., terephthalialdehyde, glyoxal, glutardialdehyde), diisocyanates (e.g., hexane-1,6-diisocyanate, toluylene diisocyanate, naphthalenediisocyanate- (1,5) and 4,4'-diisocyanatodiphenylmethane), or dicarboxylic acid anhydrides, e.g. dicarboxylic acid anhydrides (e.g., dicarboxylic acid anhydride) ) to obtain branched or crosslinked polyoxymethylenes.

Polyoxymethylenes with side ester groups are converted to the ester groups after the ester groups have been converted. the free carboxyl groups (cf. British Patent 1,191,505) interconnect with bifunctionally effective crosslinking agents, in particular by reacting with diisocyanates, diamines (e.g. phenyldiamine, hexamethylenediamine), diols [e.g. butanediol- (1,4)], hydrazine or dihydrazides. Direct reaction of the unsaponified ester groups with diols, for example butanediol- (1,4), preferably in the presence of basic transesterification catalysts, for example sodium hydroxide is also possible.

Polyoxymethylenes with side hydroxyl groups, which are obtained, for example, by copolymerization of trioxane with epichlorohydrin and exchange of chlorine atoms for hydroxyl groups by reaction of polymers with alkali metal hydroxide solutions at. at the elevated temperature, are coupled together by means of bifunctionally effective crosslinking agents, for example diisocyanates, dicarboxylic anhydrides, dicarboxylic acid esters or diketenes.

Polyoxymethylenes with side halogen atoms, preferably chlorine atoms, are converted into branched or crosslinked polyoxymethylenes by direct reaction of side halogen atoms, with alkali metal salts of organic compounds with at least two weakly acidic groups in the molecule, preferably bisphenols. such as 4,4‘-di12 hydroxydiphenyldimethylmethane or 4,4‘-dihydroxydiphenylmethane.

Linear polyoxymethylenes with double bonds in the side or main chains are converted, preferably by melt, into straight or crosslinked polyoxymethylenes by reaction with sulfur and 2-mercaptobenzthiazole.

In order to achieve crosslinked products, polyoxymethylenes with different reactive groups, for example containing aldehyde groups with those containing amino groups, can further be reacted together.

The branched or crosslinked polyoxymethylenes according to c) used according to the invention consist in the polymerization of trioxane with branched or crosslinked polyethers, optionally in the presence of at least one. known compounds for copolymerization with trioxane. In this case, mixtures of 99.99 to 50, preferably 99.8 to 70% by weight of trioxane and 0 to 20, preferably 0.1 to 10% by weight, of a compound known for copolymerization with trioxane and 0.01 to 30% are used for polymerization. %, preferably 0.1 to 20% by weight of a branched or crosslinked polyether. Best results are obtained with 98.5 to 85% by weight of trioxane, 1 to 5% by weight of at least one compound known to be copolymerized with trioxane and 0.5 to 10% by weight of a branched or crosslinked polyether.

As the branched or crosslinked polyethers, copolymers of at least one, preferably two, monofunctionally reacting cyclic ethers with 3 to 5 ring rings are used. and one bifunctionally reactive cyclic ether, i.e. an aliphatic or cycloaliphatic compound, which contains two ether groups in the ring and has 3 to 5, preferably 3 or 4 ring members.

Compounds of formula VIII serve as monofunctional cyclic ethers

CCRR-CHCH-O wherein

R and R 'are the same or different and in each case denote a hydrogen atom, an aliphatic alkyl radical having 1 to 6, preferably 1 to 3 carbon atoms, which may contain 1 to 3 carbon atoms, which may contain 1 to 3 halogen atoms, preferably chlorine, or the phenyl moiety ax is 0 or 1, or · 2.

Examples which may be mentioned are ethylene oxide, propylene oxide, isobutylene oxide, epichlorohydrin, oxacyclobutane, 3,3-bis (chloromethyl) oxacyclobutane and tetrahydrofuran.

The bifunctionally reacting cyclic ethers are, in particular, the diglycidyl ethers of α, ω-diols having 2 to 8, preferably 2 to 4, carbon atoms, 16652 ku, the carbon chain of which may in each case be interrupted by an oxygen atom or 2 digits of bisphenols or oxacyclobutyl. double substituted aliphatic or cycloaliphatic hydrocarbons having from 1 to 6 carbon atoms. Examples include 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, glycol diglycidyl ether, diglycol diglycidyl ether, triglycol diglycidyl ether, 4,4‘-bis-glycidoxyphenyldimethylmethane, 1,2-bis (3-oxacyclobu-

2,4-dioxadispiro [3.2.3.2] duodecane.

The proportion of monofunctionally reacting cyclic ethers is generally 99.99 to 98, preferably

99.95 to 99% by weight, while the proportion of bifunctionally reacting cyclic ether is between 0.01 to 2, preferably between 0.05 and 1% by weight.

The branched or crosslinked polyethers are generally prepared by known methods by copolymerizing monomers with cationic or anionic initiators. However, polyethers can also be obtained by additional grafting or condensation of linear polyethers.

The copolymerization of trioxane with the described branched or crosslinked polyethers and optionally with at least one, for copolymerization with a trioxane known compound, is carried out as already described for the production of linear trioxane copolymers.

Further, it is possible to achieve the incorporation of branched or crosslinked polyethers into linear polyoxymethylenes by mixing the polyethers and polyoxymethylenes together, preferably in the presence of a polyether solvent such as cyclohexane or methylene chloride and reacting in the presence of cationic catalysts at temperatures between 0 and 100 °. C, preferably 50 and 90 ° C. The separation of the unstable moieties or the chemical stabilization of the terminal hydroxyl groups is carried out as previously described.

The branched or crosslinked polyoxymethylenes used according to the invention have a melt flow index 12 of 0 to 50 g / 10 min, preferably 0 to 10 g / 10 min, according to DIN 53 735 at a temperature of 190 ° C and a load of 2.16 kg. A lower limit of I- ₂ equal to zero means that the polyoxymethylenes used according to the invention are not fusible or soluble above a certain degree of crosslinking, so that characterization by melt index or RSV value is not possible. Particularly suitable are branched or crosslinked polyoxymethylenes having a melt index i2 of 0.1 to 5 g / min.

In order to stabilize against the effects of heat, oxygen and light, the two components of the molding compositions according to the invention can be mixed with stabilizers and then homogenized in the melt. Suitable heat stabilizers are, for example, polyamides, polyhydric carboxylic acid amides, amidines, hydrazines, ureas and poly (n-vinyl lactams). Phenols, in particular bisphenol and aromatic amines, are used as oxidation stabilizers, and light stabilizers-α-hydroxybenzophenone and benzotriazole derivatives are used, the stabilizers being added in an amount of 0.1 to 10, preferably 0.5 to 5% by weight. % based on the total mixture.

To produce the molding compositions according to the invention, the components are always mixed together in powder or granular form and then homogenized by melting. Branched or crosslinked polyoxymethylenes with a melt index below 0.1 g / 10 min are preferably used in the form of a fine powder (grain size <1 µm).

The mixing and homogenization of the components of the molding compositions according to the invention are carried out in any, heatable mixing means, for example rolls, calenders, kneaders or extruders. The mixing temperature is conveniently above the melting point of the crystallites of the components and is 150 to 250 ° C, preferably 170 to 200 degrees Celsius.

The presence of branched or cross-linked polyoxymethylenes in the molding compositions according to the invention appears to cause nucleation in the production of moldings, which results in a reduction in spherulites and an improvement in the mechanical properties of the moldings.

For example, an increase in bead indentation hardness, elongation stress, tensile strength and torsional stiffness is observed over linear polyoxymethylenes that have not been modified. Another consequence of nucleation is an increase in the rate of crystallization, which allows faster processing. This faster workability is particularly noticeable in the shortening of the injection molding cycle and in the smaller tolerances of the injection molded parts.

The use of branched or crosslinked polyoxymethylenes as a nucleating agent for linear polyoxymethylenes is particularly advantageous in that branched or crosslinked polyoxymethylenes can be synthesized while maintaining the desired quality without the need for special purification, as is necessary, for example, with natural minerals which are suitable as nucleation agents.

The possibility of nucleation of linear polyoxymethylenes by the addition of small amounts of branched or crosslinked polyoxymethylenes is quite general. The possibilities for the production of branched or cross-linked polyoxymethylenes enumerated here cannot, of course, be complete. The production examples can only indicate some possible embodiments, but the use of branched or cross-linked polyoxymethylenes according to the invention is not limited to the use of substances prepared by a particular manufacturing process.

The inventive molding compositions can be mechanically comminuted, for example, by chopping or milling, into granules, chips, flakes or powder. They can be thermoplastically processed, for example by injection molding or extrusion. They are suitable for the production of shaped bodies which are used as polycarbonate or finished products, for example bars, rods / plates, films, strips, shells and tubes. They are particularly suitable for the production of machine parts of precise dimensions, for example gears, bearing components and operating elements.

Examples 1 to 6

Linear copolymer of 98% by weight trioxane and 2% by weight ethylene oxide having a density of 1.41 g / ml, an RSV value of 0.73 dl.g ^-1 and a melting point of crystallites of 166 ° C in powder form is mixed with 0.5% by weight bis Of (2-hydroxy-3-tert-butyl-5-methylphenyl) methane and 0.1% by weight of dicyandiamide, based on the amount of linear polyoxymethylene and with different amounts, each based on a 98% pre-stabilized crosslinked terpolymer. by weight of trioxane, 1.8 why, by weight of ethylene and 0.2 wt% of 1,4-butanediol melt index, i ₂ = 0.2 g / 10 min in the form of granules and the mixture is homogenized in a screw extruder at 200 ° C. The residence time in the extruder barrel is about 4 minutes. The polyoxymethylene mixture obtained is granulated after leaving the extruder.

The size of the spherulites is measured for the products obtained. A 10 .mu.m film is prepared by melting the granulate or shaped body between two glass plates at 180 DEG C. and allowing the melt to crystallize at 150 DEG C. under atmospheric pressure. The film is then viewed under a microscope.

In addition, the molding mass obtained is produced by injection molding a 60 x 60 x 2 mm sheet at a mass temperature of 200 ° C and at a mold temperature of 80 ° C, which are used for the ball hardness test according to VDE 0302 (load time 10 seconds). the elongation and tensile strength are always determined on 1 mm thick injection bars (1/4 proportional bar) according to DIN 53 455.

Torsional stiffness is measured on test rods made of 2 mm thick pressed plates according to DIN 53 447 at a temperature of 20 ° C and a load time of 60 seconds.

The size of the spherulites and the mechanical properties of the moldings according to the invention are shown in Table I. For comparison, linear polyoxymethylene which has not been nucleated is given.

Table 1

Example

Tensile strength (MPa) torsion (MPa)

Quantity ter- Size of sphere- Hardness of the measure- Tension at the polymer of the rolls (μιη) measured by the elongation-elongation% / mass. forging (MPa) of the remainder (MPa)

and - 350 156.0 65.0 50.6 760.0 1 0.08 32 160.0 69.0 56.0 818.0 2 0.06 0.04 38 159.0 68.5 56.0 816.0 3 40 159.0 68.0 55.0 800.0 4 0.02 45 158.0 68.0 54.5 803.0 5 0.01 55 158.0 67.0 54.0 795.0 6 0.005 65 157.5 67.0 53.0 795.0

Examples 7 to 11

97% linear copolymer! by weight of trioxane and 3% by weight of dioxolane having a density of 1.41 g.ml ^-1 , an RSV value of 0.72 dl.g ^-1 and a melting point of crystallites of 166 ° C in powder form are mixed with the stabilizers mentioned in Examples 1 to 6 of said % and in each case 0.5% by weight of trioxane powder terpolymers, 2% by weight of ethylene oxide, and a variable amount of 1,4-butanediol diglycidyl ether, and the mixture is homogenized. Table 2 shows the melt flow index of the ₂ terpolymers used and the spherulite size of the shaped articles obtained from the mixture of linear and crosslinked polyoxymethylene.

Table 2

Example trioxane content by weight Terpolymer ethylene oxide content Ю / οι weight content of butanediol diglycidyl ether (% by weight) Melt flow index (g / 10 min) Size of spherulites (<ит) b - - 530 7 97.8 2 0.2 0.06 17 8 97.4 2 0.6 0.01 13 9 97.0 2 1.0 0 15 Dec 10 98.0 2 2,0 0 11 11 95.0 2 3.0 0 9

Examples 12 to 18

Linear 'copolymer of 98% by weight of trioxane and 2% by weight of ethylene having a density of 1.41 g.ml ^1, the RSV value of 0.73 dl.g-1 and the crystallite melting point of 166 ° C, in powder form mixed with 0.5 % by weight of bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane and 0.1% by weight of dicyandiamide, based on the amount of linear polyoxymethylene and with different amounts of 98.0% by weight of trioxane stabilized crosslinked terpolymers; 95% by weight of ethylene oxide and 0.05% by weight of 1,4-butanediol diglycidyl ether having a melt index of 12 = 1.0 g / 10 min as granules and homogenized at 200 ° C in a screw extruder. The residence time in the extruder barrel is about 4 minutes.

The size of the spherulites and the mechanical properties of the molding compositions according to the invention are shown in Table 3. For comparison, linear polyoxymethylene which has not been nucleated is shown.

Table 3

Example Terpolymer amount [%!] Size of spherulites l> m] Ball Compression Hardness [MPa] Stretching stress [MPa] Tensile strength [MPa] Torsional stiffness [MPa] C - 230 157.0 65.2 51.6 760.0 12 0.5 16 158.5 70.6 56.4 818.0 13 1.0 14 159.0 71.6 56.2 816.0 14 2,0 13 160.0 72.0 56.6 814.0 15 Dec 3.0 12 161.0 72.6 56.7 826.0 16 4.0 11 162.5 72.6 55.2 830.0 17 5.0 9 161.5 72.9 57.5 843.0 18 8.0 9 161.0 72.8 56.0 845.0

Examples 19 to 23

A linear copolymer of 96% by weight of trioxane and 4%, by weight dioxolane having a density of 1.40 g.ml ^"1 RSV value of 0.68 ^dl.g-1 and the crystallite melting point of 164 ° C, in powder form mixed with stabilizers designated in Examples 12 to 18, each containing 1% by weight of the powdered terpolymers listed in Table 4 and homogenized as in Examples 12 to 18. As terpolymers, terpolymers of trioxane, 2% by weight of ethylene oxide and various amounts of 1,4-butanediol diglycidyl ether were used. The size of the spherulites is measured for the products obtained.

Table 4

Example trioxane [!%: by weight] Terpolymer of Size of spherulites [; um] ethylene oxide [% by weight] butanediol glycidyl ether [’% by weight] d - 592 19 Dec 97.9 2 0.1 6 20 May 97.5 2 0.5 14 21 97.0 2 1.0 15 Dec 22nd 96.0 2 2,0 21 23 93.0 2 5.0 17

Examples 24 to 28 *

A linear copolymer of 98% by weight of trioxane and 2% by weight of ethylene having a density of 1.41 g.ml ^1, the RSV value of 0.71 dg ¹ and a crystallite melting point of 166 ° C in powder form is mixed and homogenized with the stabilizers designated in Examples 1 to 6 in an amount therein and always with 1 why, by weight of the terpolymers of trioxane, ethylene oxide (EO) or dioxolane (DO) mentioned in Table 5 and one multifunctional reacting compound according to Examples 1 to

6. The multifunctional reacting compounds used are dicyclopentadione dioxide (I), methylene glycidylformal (II), 1,2,6-hexanetriol formal and MG 1000 (IIl), 1,2,6-hexanetriol formal (IV) and 1 formaldehyde, 2,6-hexanetriol and 1,6-hexanediol (V). Table 5 lists the melt flow indexes 12 of the cross-linked terpolymers and the spherulite sizes of the moldings obtained from the inventive molding compositions and the ball-indentation hardness and elongation stresses.

Table 5

Example trioxane [´% 'by weight] EO or DO terpolymer [0 / o by weight] vlfunctional compound [% by weight] E - 24 97.9 2 EO 0.1 I 25 97.9 2- EO 0,1 II 26 95.0 2 DO 3,0 III 27 Mar: 97.9 2 DO 0,1 IV 28 97.0 2 DO 1.0 V

Melt flow index [g / 10 min.] Size of spherulites [μΐη] Indentation hardness - balls [MPa] Elongation stress [MPa] - 387 154.5 62.0 0 9 167.5 66.0 0.08 21 158.5 64.0 0.05 19 Dec 161.5 64.5 0 16 161.5 64.5 0 8 166.0 66.0

Examples 29 to 38

A linear copolymer of 98% by weight of trioxane and 2% by weight of ethylene having a density of 1.41 g.ml ^_1 crystallite melting point of 166 ° C and RSV value of 0.73 dl.g 'and is mixed with the stabilizers indicated in Examples 1 to 6 said amount and with varying amounts of finely divided polyoxymethylene (POM I to VIII) described below and extruded in a single screw -extruderu at 190 ° C in the barrel and 180 ° C in the head of the screw at a speed of 60 ^min-1 and then granulated. The residence time in the extruder barrel is 4 minutes.

Table 6 shows the mixing ratios of linear and crosslinked polyoxymethylenes and the size of the spherulites and the hardness measured by the extrusion of the spheres of the moldings obtained from the molding compositions of the invention.

POM I

To a mixture of 1000 g of trioxane, 20 g of ethylene oxide and 30 g of methyl p-glycidoxycinnamate is added 35 ml of a catalyst solution of 1 volume of boron trifluoride dibutyl etherate in 40 volumes of cyclohexane. The mixture is polymerized in a closed vessel at a layer thickness of 0.8 cm in a constant temperature bath of 70 ° C. It is polymerized for 30 minutes. The polymer obtained is milled and treated with benizyl alcohol containing 1% by weight of triethanolamine for 30 minutes at 150 ° C to remove unstable semi-acetal end groups and residual monomers. After cooling, the polymer is suctioned off, boiled several times in methanol and dried under reduced pressure at 50 to 70 ° C. The polymer yield is 670 g, the RSV value of the polymers is 0.78 dl.g-1 and the value i2 = 1.27 g / 10 min.

The polymer obtained is then milled and irradiated with a xenon test lamp for 10 hours. Then the RSV value can no longer be measured because the polymer is only partially soluble in butyrolactone. Melting index i2 = 0.77 g / 10 min.

POM II

To a mixture of 85 g of trioxane, 5 g of dioxolane and 10 g of p-glycidoxybenzaldehyde is added 1.5 ml of catalyst solution, 1 volume of boron trifluoride dibutyl etherate in 10 volumes of cyclohexane. The mixture is polymerized - in a sealed vessel in a constant temperature bath at 70 ° C. The polymer obtained is kept at 70 DEG C. for a further 60 minutes and then, as described for POM I, treated with benzyl alcohol, washed and dried. 79 g of a white powder having an RSV value of 0.34 dl.g ^{-1 are obtained} .

The polymer was kneaded for 10 minutes in a Brabender plastograph at 195 ° C under nitrogen, with 0.5% by weight bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane and 0.1% by weight dicyandiamide. The product obtained is no longer soluble in butyrolactone, its value 22 = 0.15 g / 10 min.

POM III

10 g of a copolymer of 1000 g of trioxane, 20 g of ethylene oxide and 50 g of p-glycidoxybenzaldehyde are treated in 350 ml of benzyl alcohol for 30 minutes at 120 DEG C. with 0.3 ml of 80% by weight hydrazine hydrate solution. this will change from i2 - 156 g / 10 min to i2 = 1.0 g / 10 min.

POM IV

To 5 g of copolymers of 1000 g of trioxane, 20 g of ethylene oxide and 50 g of p-glycidoxybenzaldehyde 216652 du is added 40 mg of adipic acid bishydrazide and then stabilized with 35 mg of bis (2-hydroxy-3-tert-butyl-5-methylphenyl). enyl] methane.

After 40 minutes of melting at 190 ° C, the melt flow index i2 is immeasurably small, while before the reaction it was 165 g / 10 min.

POM V

To a mixture of 95 g of trioxane and 5 g of p-glycidoxynitrobenzene is added 0.7 ml of a catalyst solution consisting of 1 part by volume of boron trifluoride dibutyl etherate in 40 parts by volume of cyclohexane. The polymerization and processing is carried out as in pm 1, except that the polymerization time is 60 minutes. The washed and dry polymer powder is dissolved at 120-130 ° C in 2 liters of benzyl alcohol to which is added 50 ml of an 80% by weight aqueous solution of hydrozine hydrate and after dissolution. a trace of Raney nickel is added. The reaction mixture is maintained at 120-130 ° C for 30 minutes. After cooling, the polymer is aspirated, boiled in methanol and dried under vacuum at 50-70 ° C. The yield of the amine-containing polymer is 77 g, its melt index is 15.7 g / 10 min.

g of polymer was melted at 190 ° C with 200 mg of 1,4-diazobicyclo [2.2.2] octane as described for POM II. 300 mg of 4,4'-diisocyanatodiphenylmethane are added in small portions over 3 minutes. The viscosity of the melt increases strongly. After a further 3 minutes the reaction is complete. Due to the high degree of cross-linking, RSV measurement is no longer possible. Value i ₂ = 0.5 g / 10 min.

POM VI

A mixture of 9 parts by weight of trioxane and 1 part by weight of epichlorohydrin is polymerized as described for POM II using a 0.05 part by weight mixture of 20 parts by volume of cyclohexane and 1 part by volume of boron trifluoride di-n-butyl etherate. The obtained polymer block is ground and the powder is boiled in methanol for 30 minutes. After aspiration and drying at 50 ° C under nitrogen, a polymer powder with an RSV value of 0.64 dkg ^-1 and a content of 4.1% by weight is obtained.

part by weight of the polymer was stirred for 2 hours at 155 ° C, under nitrogen in an autoclave, with 1 part by weight of potassium hydroxide, 17 parts by weight of water and 33 parts by weight of methanol. The mass remaining after cooling is ground and boiled several times in methanol. After drying at 50 degrees Celsius in a stream of nitrogen, 0.6 parts by weight of a slightly yellowish powder remained, the IC spectrum of which showed significant hydroxyl bands.

125 g of bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane and 25 mg of dicyandiamide are melted in a Brabender plastograph at 190 DEG C. under nitrogen in a Brabender plastograph. After addition of 200 mg of 1,4-diazobicyclo [2.2.2] octane, a total of 500 mg of 4,4‘-diisocyanatodiphenylmethane is added in small portions. The melt viscosity is strong. rising. After an additional 5 minutes, allow to cool. The value of 12 of the product is 0.1 g / 10 min. Viscosity measurements are not possible due to the insolubility of the polymer in butyrolactone.

POM VII g of a polymer obtained similar to the preparation of POM II from 88 parts by weight of trioxane, 2 parts by weight of ethylene oxide and 10 parts by weight of p-glycidoxybenzaldehyde is melted with 125 mg of bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane at 190 ° C under nitrogen, in a Brabender plastograph. A total of 370 mg of ethylenediamine is added in small portions over 15 minutes. . After this time, the melt is completely solid. The i ₂ value of the polymer is no longer measurable.

POM VIII g of a powder copolymer of 98% by weight of trioxane and 2%. by weight of dioxolane having a melt index I ₂ 9.0 g / 10 min. is suspended in 100 ml of cyclohexane (lithium aluminum hydride dried and distilled) and 1.0 ml of 1,4-butanediol diglycidyl ether and 0.15 ml of boron trifluoride di-n-butyl etherate are added with stirring. C and treated with benzyl alcohol as described for POM I, washed and dried The polymer i 2 value is not measurable.

Example

Linear РОМ [% by weight]

Table 6

Branched or Spherulite size Indentation hardness reticulated POM [μΐη] balls [MPa] [% by weight]

F 100 ALIGN! - 550 154.5 29 99 1 POM I 15 Dec 163.5 30 99 1 POM II 7 161.5 31 97 3 POM II 6 164.5 32 99 1 POM III 10 161.0 33 99 1 POM IV 12 161.5 34 99 1 POM v 25 160.0 35 99 1 POM VI 10 161.5 36 99.95 0.05 POM VII 30 160.0 37 99 1 POM VII 25 160.5 38 97 3 POM VIII 16 161.0

Example 39

Linear homopolymer of formaldehyde acetal groups having a density of 1.45 g.ml ^1, the RSV value of 0.70 ^dl.g-1 and the crystallite melting point of 174 ° C is mixed with stabilizers designated in Examples 1-6 in the amounts referred to therein and 2 % of the POM IV used in Example 33 and the mixture was homogenized and granulated as described in Examples 29-38. Table 7 shows the spherulite size and bead indentation hardness compared to the modified homopolymers.

Table 7

Example Linear POM [° / o weight] Branched or reticulated POM [° / o weight] Size of spherulites [μΠΊ] Ball hardness [MPa] G 100 ALIGN! - 482 174.0 39 98 2 POM IV 27 Mar: 179.0

Examples 40 and 41

A linear copolymer of 98% by weight trioxane and 2% by weight ethylene oxide having a density of 1.41 g.ml ^-1 , with a crystallite melting point of 166 ° C and an RSV value of 0.73 dl.g ^-1 is mixed with the stabilizers mentioned in Examples 1 to 6 in the amounts indicated therein and why, by weight of the POM IX and POM X described below, and the mixture is homogenized and granulated as in Examples 29-38. Table 8 shows the spherulites of the moldings obtained from the molding compositions of the invention.

POM IX

To 100 g of a mixture of 26,75 parts by weight of trioxane, 2 parts by weight of dioxolane and

1.25 parts by weight of a polyether of tetrahydrofuran, ethylene oxide and 2,9-dioxa-dispiro [3.2.3.2] dodecane in a 50:50: 0.05 ratio by weight is added 0.3 ml of catalyst solution and 1 part by volume of boron trifluoride dibutyl etherate, and 20 parts by volume of cyclohexane and polymerized for 30 minutes at 70 degrees Celsius.

said polyether is prepared by polymerizing 100 g of a mixture of monomers each using 150 mg of triphenylmethylhexafluorophosphate as a catalyst in aluminum tubes at 20 degrees Celsius. The polymerization time is 24 hours, the treatment is carried out by steam distillation.

The polyoxymethylene obtained is cooled to 0 ° C and immediately ground to a fine powder. The powder at 50 g polymer / 1000 ml was degraded in methanol: water: triethylamine solution as 66: 34: 0.1 (v / v) in an autoclave under nitrogen, at 150 ° C, for 30 minutes. It is then thoroughly washed with acetone and dried at 70 degrees Celsius in a stream of nitrogen. The product obtained has a melt index i ₂ = 2.8 g / 10 min.

POMX

The preparation is carried out as POM IX, but a terpolymer of tetrahydrofuran, ethylene oxide and 1,4-butanediol diglycidyl ether in a weight ratio of 50: 50: 0.5 is used as the polyether. The polymer block obtained has a melt index i ₂ = 4.1 g / 10 min.

Claims (5)

OBJECT OF THE INVENTION Thermoplastic molding composition, characterized in that it consists of a mixture of 99.999 to 90% by weight of linear polyoxymethylene and 0.001 to 10% by weight. branched or cross-linked polyoxymethylene. 2. The thermoplastic molding composition of claim 1, wherein the branched or crosslinked polyoxymethylenes are copolymers of trioxane and trioxane copolymerizable, multifunctional reacting compounds, and optionally trioxane copolymerizable, monofunctional reacting compounds. 3. The thermoplastic molding composition according to claim 1, wherein the branched or crosslinked polyoxymethylenes are additionally branched or crosslinked linear polyoxymethylenes having side or chain functional groups. 4. The thermoplastic molding composition of claim 1, wherein the branched or crosslinked polyoxymethylenes are copolymers of trioxane and copolymerizable, monofunctional reacting compounds and branched or crosslinked polyether. 5. The thermoplastic molding composition of claim 1, wherein the proportion of linear polyoxymethylene is 99.9 to 90. and the proportion of branched or crosslinked polyoxymethylene is 0.1 to 10.0% by weight.