WO1999050339A1

WO1999050339A1 - Method for producing thermoplastic powders

Info

Publication number: WO1999050339A1
Application number: PCT/EP1999/002002
Authority: WO
Inventors: Martin Weber; Jürgen AHLERS; Christoph Minges
Original assignee: Basf Aktiengesellschaft
Priority date: 1998-03-31
Filing date: 1999-03-24
Publication date: 1999-10-07
Also published as: AR019015A1; AU3599099A; DE19814352A1

Abstract

The invention relates to a method for producing thermoplastic powders. In a first step, the melt of a thermoplastic polymer A is mixed with a polymer B, polymer B being incompatible with polymer A. In a second step, a dispersion of polymer A in a solution of polymer B in a solvent is produced from the mixture. The powder is then isolated from the dispersion. The invention also relates to powders of thermoplastic polymers produced according to this method and to the use of these powders for producing dispersions.

Description

Process for the production of thermoplastic powders

description

The present invention relates to a method for producing powders of thermoplastic polymers.

Thermoplastic powders are of interest for many applications, in particular for coatings. It is usually difficult to produce fine powders with a narrow particle size distribution, the particles of which are essentially round and have an essentially smooth, pore-free surface. When grinding ^¬ moplastische ther polymers must be cooled, and the particles obtained thereby also have irregular surfaces. Simply dissolving the thermoplastic polymers and precipitates is often forbidden due to the poor solubility of the polymers in question or the precipitation process must be carried out under the action of high shear forces, which leads to fibril-like particles being obtained.

From DE-A 43 01 543 it was known to produce micropowder by spray drying polyarylene ether solutions by atomizing the solutions into an inert gas. In this process, the solvent is evaporated. As a result, particles with an essentially smooth surface structure and diameters in the range from approximately 1 to approximately 500 μm are obtained. In this process, high temperatures and amounts of gas are necessary, so that there is still room for improvement in terms of economy.

It was known per se to produce two-phase mixtures from mutually incompatible polymers and then to remove one of the blend components. However, according to EP-Al-246 752, fibers are first spun from the blend. The fiber structure is retained even after the soluble polymer has been removed. According to EP-Al-164 235, 417 908 and 548 492, films are produced from the mixtures in a first step. The soluble polymers are extracted from these, whereby porous membranes can be obtained.

The object of the present invention was to provide a method for producing thermoplastic powders, by means of which powders with average particle sizes in the micrometer range are accessible, which are essentially spherical and have an essentially smooth surface structure. Furthermore, the particle size distribution should be as narrow as possible. Furthermore, a method should be found using the powder of the most varied 2 thermoplastic polymers can be produced. The desired process should also be feasible with the simplest possible technical means.

This object is achieved by the process according to the invention in which powders of thermoplastic polymers are prepared by mixing the melt of a thermoplastic polymer A with a second polymer B which is incompatible with A in a first step and from the Mixture a dispersion of the polymer A in a solution of the polymer B in a solvent and then the powder is isolated from the dispersion.

In principle, all polymers which can be melted, i.e. processable thermoplastically. The preferred thermoplastic polymers A include polyarylene ethers, polyimides, polyamides, polyoximethylene, syndiotactic polystyrenes or polyesters. If a powder is to be produced from a mixture of different thermoplastic polymers, a melt of two or more different thermoplastic polymers A can also be used.

Polyarylene ethers are known per se or can be obtained by methods known per se. Suitable polyarylene ethers include polyphenylene ethers, polyarylene ether sulfones, preferably polyphenylene ether sulfones, polyarylene ether ketones, in particular polyphenylene ether ketones.

The polyphenylene ethers in question are particular

Compounds based on substituted, in particular disubstituted polyphenylene ethers, the ether oxygen of one unit being bound to the benzene nucleus of the adjacent unit. Polyphenylene ethers which are substituted in the 2- and / or 6-position relative to the oxygen atom are preferably used. Examples of substituents are halogen atoms, such as chlorine or bromine, and alkyl radicals with 1 to 4 carbon atoms, which preferably have no α-tertiary hydrogen atom, for example methyl, ethyl, propyl or butyl radicals. The alkyl radicals can in turn be substituted by halogen atoms, such as chlorine or bromine, or by a hydroxyl group. Further examples of possible substituents are alkoxy radicals, preferably having up to 4 carbon atoms, such as methoxy, ethoxy, n-propoxy and n-butoxy, or phenyl radicals optionally substituted by halogen atoms and / or alkyl groups. Copolymers of various phenols are also suitable, for example copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol. Self- 3 understandably, mixtures of different polyphenylene ethers can be used.

Examples of polyphenylene ethers are poly (2,6-dilauryl-1,4-phenylene ether), poly (2,6-diphenyl-1,4-phenylene ether), poly (2,4-dimethoxy-1,4-phenylene ether), poly (2,6-diethoxy-1,4-phenylene ether), poly (2-methoxy-6-ethoxy-1,4-phenylene ether), poly (2-ethyl-6-stearyloxy-1,4-phenylene ether), poly- (2,6-dichloro-1,4-phenylene ether), poly (2- methyl-6-phenyl-1,4-phenylene ether), pol (2,6-dibenzyl-1,4-phenylene ether), poly (2-4 ethoxy-1,4-phenylene ether), poly (2-chloro-1,4-phenylene ether), poly (2,5-dibromo-1,4-phenylene ether). Polyphenylene ethers in which the substituents are alkyl radicals having 1 to 4 carbon atoms are preferably used; poly (2,6-dialkyl-1,4-phenylene ether), such as poly (2,6-dimethyl-1,4-phenylene ether), poly (2,6-diethyl-1,4), have proven to be particularly suitable -phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), poly (2-methyl-6-propyl-1,4-phenylene ether), poly (2, 6- dipropy1-1, 4 - phenylene ether and poly (2-ethyl-6-propyl-1,4-phenylene ether). Poly (2,6-dimethyl-1,4-phenylene ether) is particularly preferably used.

With regard to the physical properties of the polyphenylene ethers, preference is given to using those which have an average molecular weight M _w (weight average) of 8000 to 70,000, preferably 12,000 to 60,000 and in particular 25,000 to 50,000. This corresponds to an intrinsic viscosity of approximately 0.18 to 0.7, preferably 0.25 to 0.62 and in particular 0.39 to 0.55 dl / g, measured in chloroform at 25 ° C.

The molecular weight distribution is generally determined by means of gel permeation chromatography (Shodex separation column 0.8 × 50 cm of the types A 803, A 804 and A 805 with tetrahydrofuran (THF) as eluent at room temperature). The solution of the PPE samples in THF is carried out under pressure at 110 ° C., 0.16 ml of a 0.25 wt. -% solution to be injected. The detection is generally carried out with a UV detector. The columns are calibrated using PPE samples, the absolute molecular weight distributions of which have previously been determined by a GPC-laser-light-scattering combination.

Suitable polyphenylene ether sulfones or ketones include those with at least one of the following recurring structural units,

(Ii)

CH ₃ ^~ o- - ° ^ yr (I ₂ )

(13)

° ^ ° ^ o ^ ^o ^ ^sθ2 ^ -; ι)

'(15)

^• - ^ C? ^ F ₃ ° ^ - ^so {—I-

(i ₆ )

[I?)

₀ - _< Q Q-0HQ> -S0 ₂ ^ - (i ₈ )

° - ^{"o""sθ2~" sθ2} ^^ ^"(l9

CH ₃ dio)

CH ₃

CH ₃ CH ₃ -

13 ' ° ^ C7 ^ ζ} - ° ^~ C ^sθ2 ^ ^~ dl4)

-CH _3rd

CH ₃

f \ _^ fY ° -Q- ^« ^ Q ^~ : ι ₅ )

CH ₃ -

^{o →} (^ ^o ^ 0 ^ die)

0 ^{~ ~}

_ ^. o- ^ o ^^ 0 "-Q- _° -0 ~ Ul7>

w 0- // w // \\ die)

cTT Q ^ o ^ -l _^ - dι ₉ ⁾

0

i- L: ι ₂ o)

^■ 0- (121)

0 0

(22)

| - OO

- O- (123)

OO o ^ -i ^ Q _^ Q Q .. d ₂ ) 0 o -70- ^ c ^ 0 / V d ₂₅ ⁾

0 0

- ° ^"" O ^{~ O_ ~ "~ ~} (126)

15 0

^• 0 -

^» O-

- (128)

0 0

20 d ₂₉ ⁾

25 Particularly preferred units of the formula I are units of the formulas Iχ and I which can be present individually or in a mixture.

The polyarylene ether sulfones or ketones can also be co- or

30 block copolymers in which polyarylene ether segments and segments of other thermoplastic polymers, such as polyamides, polysiloxanes, polyimides or polyetherimides are present. The molecular weights (number average) of the block or graft arms in the copolymers are generally in the range from 1000 to

35 30,000 g / mol. The blocks of different structures can be arranged alternately or statistically. The proportion by weight of the polyarylene ether sulfones or ketones in the copolymers or block copolymers is generally at least 10% by weight. The weight fraction of the polyarylene ether sulfones or ketones can be up to

40 97% by weight. Co or block copolymers with a weight fraction of polyarylene ether sulfones or ketones with up to 90% by weight are preferred. Co or block copolymers with 20 to 80% by weight of polyarylene ether sulfones or ketones are particularly preferred.

45 7

Mixtures of different polyarylene ether sulfones or ketones or mixtures of polyarylene ether sulfones and polyarylene ether ketones can of course also be used.

In general, the polyarylene ether sulfones or ketones have average molecular weights M _n (number average) in the range from 5,000 to 60,000 g / mol and relative viscosities from 0.20 to 0.95 dl / g. Depending on the solubility of the polyarylene ether sulfones or ketones, the relative viscosities are either in 1% by weight N-methylpyrrolidone solution, in mixtures of phenol and dichlorobenzene or in 96% by weight. -% sulfuric acid measured at 20 ° C and 25 ° C respectively.

In principle, all known, linear or branched, polyarylene sulfides can also be used in the process according to the invention. In addition, it is also possible to use mixtures of different polyarylene sulfides as polymers A. However, preference is given to polyarylene sulfides which contain more than 30 mol%, in particular more than 70 mol%, of repeating units

(II)

contain. As other repeating units are example ^¬ to name as:

_s _

s or _ ^ Λ

⁽ R ⁾ n

wherein R is a C 1 -C ₂ alkyl radical, preferably methyl, and n is either 1 or 2. The polyarylene ether sulfides can be both random copolymers and block copolymers. Very particularly preferred polyphenylene sulfides contain 100 mol% of units II.

The preferred polyarylene sulfides have a molecular weight (number average) M _n of 1000 to 100,000 g / mol. The molecular weight is determined by light scattering in α-chloronaphthalene. 8th

The process according to the invention can also be used to produce powders from polyimides, including preferably polyetherimides. Processes for the production of polyimides or polyetherimides are known to the person skilled in the art.

Suitable polyetherimides comprise as essential groups again ^¬ units of the formula III,

0 o C II

N c.

0- 0 N-. _R l. (III)

0

where Z is a divalent aromatic organic radical having 6 to 30 carbon atoms and R ^{1 is} a divalent organic radical consisting of

a) aromatic hydrocarbons with 6 to 20 carbon atoms and / or their halogenated derivatives,

b) alkylene residues, polydiorganosiloxane residues and cycloalkylene residues with up to 20 C atoms or

c) divalent radicals of the formula IV

(T) (IV)

where - (T) - for

-0-, - (CO) -, - (S0 ₂ ), -S- or -C _b H _2b - (b = 1 to 5) and a has a value of 0.1 or 2. 9

Products in which R ^{1 has} the meaning given above and Z for a group of the formula V are particularly preferred

CH ₃

- (V)

CH ₃

stands.

Optionally, as a further recurring units Grup ^¬ pen of the formula VI

O

NN Rl- (VI)

O

be included, wherein R ^{1 has} the meanings given above.

In general, the polyetherimides have molecular weights M _w (weight average) in the range from 2000 to 100,000 g / mol, preferably in the range from 2500 to 80,000 g / mol. The molecular weight is determined by light scattering.

The polyamides, which can also be used as polymer A in the process according to the invention, are known per se or can be obtained by methods known per se. Both amorphous and partially crystalline polyamides can be used. Mixtures of different types also come as polymers A.

Consider polyamides. The polyamides can e.g. by condensation of equimolar amounts of a saturated or an aromatic dicarboxylic acid with 4 to 12 carbon atoms, with a saturated or aromatic diamine which has up to 14 carbon atoms or by condensation of ω-aminocarboxylic acids or polyaddition of corresponding lactams.

Examples of such polyamides are polyhexamethylene adipic acid amide (nylon 66), polyhexamethylene azelaic acid amide (nylon 69), polyhexamethylene sebacic acid amide (nylon 610), polyhexamethylene dodecanoic acid amide (nylon 612), the polyamides obtained by ring opening of lactams such as polycaprolactam, polylauric acid lactam 10 further poly-11-aminoundecanoic acid and a polyamide of di (p-amino-cyclohexyl) methane and dodecanedioic acid.

It is also possible to use polyamides which have been prepared by copolycondensation of two or more of the abovementioned polymers or their components, for example copolymers of adipic acid, isophthalic acid or terephthalic acid and hexamethylene diamine or copolymers of caprolactam, terephthalic acid and hexamethylene diamine. Such partially aromatic copolyamides contain, for example, 20 to 90% by weight of units which are derived from terephthalic acid and hexamethylenediamine. A small proportion of terephthalic acid, preferably not more than 10 wt -.%, Of the total aromatic dicarboxylic acids used can be acid by isophthalic ^¬ or other aromatic dicarboxylic acids, preferably those in which the carboxyl groups are in para position, it sets ^¬.

In addition to units derived from terephthalic acid and hexamethylene diamine ^¬ which contain partly aromatic copolyamides of units derived from ε-caprolactam and / or units derived from adipic acid and hexamethylenediamine.

Polyamides with 50 to 80, in particular 60 to 75,% by weight units derived from terephthalic acid and hexamethylenediamine and 20 to 50, preferably 25 to 40,% by weight units, which differ from ε, have proven to be particularly advantageous for many applications -Caprolactam derived, proven.

Cyclic diamines are also suitable as monomers. Particularly preferred cyclic diamines are bis (4-aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, bis (4-aminocyclohexyl) -2, 2-propane or bis (4-amino-3-methylcyclo) - hexyl) -2, 2-propane. 1,3- or 1,4-cyclohexanediamine or isophoronediamine may be mentioned as further cyclic diamines.

Further monomeric building blocks of the polyamides can be aromatic diacarboxylic acids with generally 8 to 16 carbon atoms. Suitable aromatic dicarboxylic acids are, for example, substituted terephthalic and isophthalic acids such as 3-t-butylisophthalic acid, polynuclear dicarboxylic acids, eg. B. 4,4'- and 3, 3'-diphenyldicarboxylic acid, 4,4'- and 3, 3'-diphenylmethanedicarboxylic acid, 4,4'- and 3, 3'-diphenylsulfonedicarboxylic acid, 1,4- or 2 6-naphthalene dicarboxylic acid and phenoxy terephthalic acid.

For example, further polyamide-forming monomers can acids having 4 to 16 carbon atoms and aliphatic diamines having 4 to 16 carbon atoms and from aminocarboxylic acids or from dicarboxylic ^¬ Derive 11 corresponding lactams with 7 to 12 carbon atoms. Suitable monomers of these types here are only suberic acid, azelaic acid or sebacic acid as representatives of the aliphatic dicarboxylic acids, 1, 4-butanediamine, 1, 5-pentanediamine or piperazine, as representatives of the diamines and caprolactam, capryllactam, oanthanthactam, laurolactam and ω- Aminoundecanoic acid as a representative of lactams or aminocarboxylic acids.

Preferred polyamides are polyhexamethylene adipic acid amide, polyhexamethylene sebacic acid amide and polycaprolactam as well as polyamide 6 / 6T and polyamide 66 / 6T as well as polyamides which contain cyclic diamines as comonomers.

The polyamides generally have a relative viscosity of 2.0 to 5, determined on a 1 wt. -% solution in 96% sulfuric acid at 23 ° C, which corresponds to a molecular weight (number average) of about 15,000 to 45,000. Polyamides with a relative viscosity of 2.4 to 3.5, in particular 2.5 to 3.4, are preferably used.

Polyamides may also be mentioned, e.g. can be obtained by condensing 1,4-diaminobutane with adipic acid at elevated temperature (polyamide 4.6).

Polyoximethylenes suitable as polymers A can be homo- or

Copolymers. Such polymers are known per se to the person skilled in the art and are described in the literature.

In general, these polymers have at least 50 mol% of recurring -CH ₂ 0- units in the main polymer chain.

The homopolymers are generally prepared by polymerizing formaldehyde or trioxane, preferably in the presence of suitable catalysts.

In the context of the invention, preference is given to polyoxymethylene copolymers which, in addition to the repeating units -CH ₂ 0-, also contain up to 50, preferably 0.1 to 20, in particular 0.3 to 10 mol% and very particularly preferably 2 to 6 mol% recurring units 12

R ² R ³

OCC (R ⁵ ) n (VII) Rl R4

where R ¹ to R ⁴ independently of one another are a hydrogen atom, a C 1 -C ₄ -alkyl group or a halogen-substituted alkyl group with 1 to 4 C atoms and R ^{5 is} a -CH ₂ -, -CH0-, a Ci-to C ₄ - Alkyl or Ci-to C-haloalkyl substituted methylene group or a corresponding oxymethylene group represent ^¬ len and n has a value in the range of 0 to 3. These groups can advantageously be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula

R2 R ^l - c— 0

| I (VIII)

R3 c (R5) _n

R4

where R ¹ to R ⁵ and n have the meaning given above. Examples include ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 1,3-dioxane, 1,3-dioxolane and 1,3-dioxepane as cyclic ethers and linear oligo- or polyformals such as polydioxolane or polydioxepane as comonomers.

Also suitable are oxymethylene terpolymers which, for example, by reacting trioxane, one of the cyclic ethers described above with a third monomer, preferably bifunctional compounds of the formula

CH ₂ CH CH ₂ Z CH ₂ CH CH ₂

VV and / or ^(IX)

13 where Z is a chemical bond, -0-, -0R0- (R = Cχ to Cβ alkylene or C _{2 to} C ₈ cycloalkylene) are produced.

Preferred monomers of this type are ethylene diglycide, diglycidyl ether and diether from glycidylene and formaldehyde, dioxane or trioxane in a molar ratio of 2: 1 and diether from 2 mol of glycidyl compound and 1 mol of an aliphatic diol with 2 to 8 C atoms, such as for example the diglycidyl ethers of ethylene glycol, 1,4-butanediol, 1,3-butanediol, cyclobutane-1,3-diol, 1,2-propanediol and cyclohexane-1,4-diol, to name just a few examples.

End group-stabilized polyoxymethylene polymers which have C-C bonds at the chain ends are particularly preferred.

Mixtures of different polyoxymethylenes are reversible also ^¬ ver.

The preferred polyoxymethylene copolymers have melting points of at least 150 ° C. and molecular weights (weight average) M _w in the range from 5000 to 200000, preferably from 7000 to 150,000 (determined by means of light scattering in hexafluoroisopropanol).

The syndiotactic vinyl aromatic polymers which can also be used as polymer A are preferably composed of vinyl aromatic compounds of the general formula I

in which the substituents have the following meaning:

R ^{1 is} hydrogen or C ¹ -C ₄ -alkyl,

R ² to R ^{6 are} independently hydrogen, Ci to

C ₂ alkyl, C ₆ to C ₈ aryl, halogen or where two adjacent radicals together represent 4 to 15 C atoms pointing to cyclic groups.

Vinylaromatic compounds of the formula I are preferably used, in which

R ^{1 is} hydrogen and 14

R ² to R ^{6 are} hydrogen, Ci to C ₄ alkyl, chlorine, phenyl,

Biphenyl, naphthalene or anthracene or where two adjacent radicals together represent cyclic groups having 4 to 12 carbon atoms, so that, for example, as a compound of the general formula I

Naphthalene derivatives or anthracene derivatives result.

Examples of such preferred compounds are:

Styrene, p-methylstyrene, p-chlorostyrene, 2, 4-dimethylstyrene, 4-vinylbiphenyl, vinylnaphthalene or vinylanthracene.

Mixtures of different vinyl aromatic compounds can also be used, but preferably only one vinyl aromatic compound is used.

Particularly preferred vinyl aromatic compounds are styrene and p-methylstyrene.

Mixtures of different vinyl aromatic polymers with a syndiotactic structure can also be used, but preferably only one vinyl aromatic polymer is used, in particular syndiotactic polystyrene.

Vinyl aromatic polymers with a syndiotactic structure and processes for their preparation are known per se and are described, for example, in EP-A 535 582. The preparation is preferably carried out by reacting compounds of the general formula I in the presence of a metallocene complex and a cocatalyst. In particular pentamethylcyclopentadienyltitanium trichloride, pentamethylcyclopentadienyltitanium trimethyl and pentamethylcyclopentadienyltitanium trimethylate are used as metallocene complexes.

The vinyl aromatic polymers with a syndiotactic structure generally have a molecular weight M _w (weight average) of 5000 to 10,000,000, in particular 10,000 to 2,000,000. The molecular weight distributions M _w / M _n (M _n number average) are generally in the range from 1.1 to 30, preferably from 1.4 to 10.

Polyesters are further polymers from which powders can be produced by the process according to the invention. In principle, all thermoplastic polyesters or mixtures of different polyesters can be used. Polyesters are known per se or can be produced by methods known per se. 15

Suitable polyesters include polyesters derived from at least one aliphatic, cycloaliphatic, aromatic or arylaliphatic diol or a mixture of these diols and at least one aromatic dicarboxylic acid or its reactive derivatives such as dialkyl esters, e.g. Derive dimethyl esters or anhydrides or mixtures of these compounds.

In general, the aliphatic or cycloaliphatic diols have from 2 to 10, preferably from 2 to 6, carbon atoms. However, glycols which can have up to 50, preferably from 2 to 20, carbon atoms, for example, are also suitable as aliphatic diols. These longer-chain diols are mostly used in a mixture with shorter-chain diols and are generally used there as a subordinate component. Examples of preferred aliphatic diols are 1,2-dihydroxyethane, 1,4-dihydroxy-n-butane, propylene glycol, diethylene glycol or triethylene glycol. The preferred cycloaliphatic diol is 1,4-dihydroxycyclohexane.

The aromatic or arylaliphatic diols generally have from 6 to 20 carbon atoms. Preferred aromatic or arylaliphatic diols are, for example, 4,4'-dihydroxydiphenyl, 2,2-bis (4-hydroxypheny1) propane, 2,4-bis (4-hydroxypheny1) -2-methylbutane, 1,1- Bis- (4-hydroxypheny1) cyclohexane. Further preferred diols are hydroquinone or resorcinol. 2,2-bis - (4-hydroxypheny1) propane and 1,1-bis (4-hydroxypheny1) cyclohexane and 1,1-bis (4-hydroxypheny1) -2,3,5-trimethylcyclohexane are particularly preferred and 1, 1-bis (4-hydroxypheny1) -3, 3, 5-trimethylcyclohexane.

The preferred aromatic dicarboxylic acids include CQ to C ₂ o-dicarboxylic acids. Terephthalic acid, isophthalic acid or 1, 2-naphthalenedicarboxylic acid or their derivatives are particularly preferably used.

Thermotropic polyesters, i.e. Polyesters which have liquid-crystalline properties in a certain temperature range can also be used as polymers A.

Preferred thermotropic polyesters have repeating structural elements 16

o o

- C - Ar ² - fE - Ar ³ -) - C - (XI) - O - Ar ⁴ - -E - Ar ⁵ - - 0 (XII) ns

or mixtures of these structural elements.

Ar, Ar ¹ , Ar ² , Ar ³ , Ar ⁴ and Ar ⁵ each represent arylene groups which can have 6 to 18 carbon atoms, such as phenylene, naphthylene or biphenylene. The arylene groups can be unsubstituted or have substituents. These substituents include C 1 -C 1 -alkyl radicals as defined above and

Cι ~ to C ₄ alkoxy groups, such as methoxy, ethoxy or n-butoxy. In addition, the substituents can also be phenyl radicals or halogen atoms, in particular chlorine. The variable s can have the value 0 or 1 and E means S0 ₂ or a 1,4-benzoquinone residue.

For example, such thermotropic polyesters are derived from one or more of the following monomeric building blocks: p-hydroxybenzoic acid, m-hydroxybenzoic acid, terephthalic acid, isophthalic acid, hydroquinone, phenylhydroquinone, alkyl-substituted hydroquinones, in particular 2-methylhydroquinone, 2-ethylhydroquinone, 2-n-propylhydroquinone, 2-i-propylhydroquinone, 2-t-butylhydroquinone, halogen-substituted hydroquinones, in particular 2-chloro-hydroquinone. Further examples of suitable monomers are 4,4'-dihydroxydiphenyl ether, 1,3-dihydroxybenzene, 4,4'-biphenol, 2, 6,2 ', 6'-tetramethylbiphenol, 2,6-dihydroxynaphthalene, 2,7-di-hydroxynaphthalene , 2,6-naphthalenedicarboxylic acid, 6-hydroxy-2-naphthalenecarboxylic acid, 4,4'-bis (p-hydroxyphenoxy) diphenylsulfone, 2,6-dihydroxyanthraquinone, 4,4'-diphenyletherdicarboxylic acid or 4,4'-dihydroxybenzophenone.

The suitable polyesters can be linear or branched, preferably by incorporating 0.05 to 2.0 mol%, based on the sum of the diols used, of at least trifunctional compounds, for example those having three or more than three OH groups.

Particularly preferred polymers A) are polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or polybutylene naphthalate or mixtures thereof. 17

As a rule, the thermoplastic polyesters are characterized by a viscosity number in the range from 50 to 170, preferably from 60 to 160 ml / g (measured in 0.5% strength by weight solution in a mixture of phenol and 1,2-dichlorobenzene in the weight Ratio 1: 1 at a temperature of 25 ° C).

According to the invention, the melt of polymer A is mixed with a polymer B, the latter being incompatible with A. Examples of suitable polymers B are polyarylene ether sulfones if polyarylene ether ketones are used as polymers A. If polyarylene ether sulfones or mixtures of polyarylene ether sulfones with polyarylene ether ketones are used as polymers A, polyesters or polycarbonates can function as polymers B. Polyoximethylenes are essentially incompatible with polyalkylene glycols, so that polyethylene glycols can be used as component B for the production of polyoxymethylene powders.

Polycarbonates are known per se or are obtained by processes which are known to the person skilled in the art.

Suitable polycarbonates are, for example, those based on diphenols of the general formula XIII

HO,

XIII

m

wherein Q is a single bond, a Ci to Cs alkylene, a

C ₂ - to C ₃ -alkylidene, a C ₃ - to C ₆ -cycloalkylidene group, a C ₆ - to C ₁₂ -arylene group and -0-, -S- or -S0 - means and m is an integer from 0 to 2 is.

The diphenols I can also have substituents on the phenylene radicals, such as C ₁ -C ₆ -alkyl or C ₁ -C ₆ -alkoxy.

Preferred diphenols of the formula I are, for example, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, 2,2-bis (4-hydroxyphenyl) propane, 2,4-bis (4-hydroxypheny1) -2 - methyl butane,

1, 1 -Bis- (4-hydroxypheny1) cyclohexane. 2,2-bis (4-hydroxypheny1) propane and 1,1-bis (4-hydroxyphenyl) cyclohexane, and 1,1-bis (4-hydroxypheny1) -3, 3, are particularly preferred. 5 -trimethylcyclohexane. 18th

Both homopolycarbonates and copolycarbonates are suitable as polymers B; in addition to the bisphenol A homopolymer, the copolycarbonates of bisphenol A are preferred.

The suitable polycarbonates can be branched in a known manner, preferably by incorporating 0.05 to 2.0 mol%, based on the sum of the diphenols used, of at least trifunctional compounds, for example those having three or more than three phenolic compounds OH groups.

Polycarbonates which have relative viscosities η _re χ of 1.10 to 1.50, in particular of 1.25 to 1.40, have proven particularly suitable. This corresponds to average molecular weights M _w (weight average) from 10,000 to 200,000, preferably from 20,000 to 80,000.

Polyalkylene glycols which are derived from aliphatic diols can be used. Polyethylene glycol, polypropylene glycol or polybutylene glycol are particularly preferred. However, copolymers can also be used. Polyethylene glycols are particularly preferably used because they are readily water-soluble. The molecular weights M _w (weight average values) are generally in the range from 1000 to 100,000 g / mol. The preparation of the polyalkylene glycols is known per se or can still be carried out using methods known per se.

Mixtures of different polymers can also be used as polymer B. Particularly preferred polymers B which ^¬ serlösliche polymers used, including, for example, polyvinyl pyrrolidone or polyvinyl alcohols.

Compatibility of two polymer components is generally understood to mean the miscibility of the components or the tendency of one polymer to dissolve in the other polymer component (see B. Vollmert, floor plan of macromolecular chemistry, BD IV, p. 222 ff, E. Vollmert-Verlag 1979). Methods that can be used to determine the compatibility of polymers are, for example, turbidity measurements or scattering methods (light scattering) (LA Utracki "Polymer Alloys and Blends", pp. 34-42, Hanser Verlag New York 1989). Polymers which are incompatible with one another form phase boundaries, one polymer being dispersed in the other polymer, the matrix phase. The particle size of the dispersed particles depends on the nature of the two polymers, in particular their viscosity ratios, but also on the shear rate to which the polymers are subjected during the mixing process. The particle size can therefore vary within a wide range, but affects the particle size 19 the powder. Which of the polymers forms the matrix phase depends in the first approximation on the volume ratio (( _A / itäts _B ) and viscosity ratio (Π _A / ^ _B ) of the polymers used and is determined by the equation <PA / <PB = ^ _A / _B certainly.

As a rule, the viscosity ratio of A to B is from 1: 0.01 to 1: 100. The viscosity ratio is preferably in the range from 1: 0.1 to 1:10.

In the preparation of the polymer mixture, a shear field is generally generated by mixing the melt of polymer A with polymer B in a mixing unit such as a kneader, a mill or, preferably, an extruder. However, it is also possible to generate a shear field in another way, for example using other mechanical or hydraulic rotating tools. The shear rate of an extruder is proportional to the speed (n) and the screw diameter (d) and inversely proportional to the depth h: γ = (π n d) / h.

Shear gradients in the range from 1 to 10 ⁴ HZ, preferably in the range from 5 to 5 * 10 ³ HZ, are generally used.

The polymer B can be introduced into the melt of the polymer A as a solid, for example as a powder or granulate, but also as a melt. However, it is also possible to introduce the polymer B and to enter the polymer melt from A.

The particle sizes (average particle diameter) of the polymer A in B are generally from 0.01 to 50, preferably from 0.05 to 25 μm. The particle sizes were determined by means of light scattering or microscopy.

The matrix phase usually makes up at least about 50% by volume of the polymer mixture. However, the volume fraction of polymer B can also be smaller, for example up to 20% by volume.

The mixture of the polymers A and B can be cooled and comminuted, for example granulated. However, it can also be processed further from the melt.

According to the invention, the mixture is used to produce a dispersion which contains polymer B dissolved in a solvent and which contains polymer A dispersed in this solution. 20th

Preferred solvents are those which dissolve polymer B sufficiently well, but which do not or only poorly dissolve polymer A. Solvents are preferred which do not dissolve or swell the polymers A or swell as little as possible. Particular preference is given to using water as the solvent if possible. For the purposes of the present invention, a solvent is also understood to mean liquids which completely or partially degrade the polymer, for example by adding acids, bases or nucleophiles. Suitable solvents are known to the person skilled in the art. Examples include tetrahydrofuran for the combination polyarylene ether ketone as A and polyarylene ether sulfone as B, water for the combination polyoximethylene as A and polyalkylene glycol as B and aqueous base for the combination polyarylene ether sulfone as A and polycarbonate as B.

According to the invention, the powder of the thermoplastic polymer A is isolated from the dispersion. Different methods can be used for this. The dispersion is particularly preferably filtered or centrifuged and the powder is thus obtained.

The powders have a narrow particle size distribution. The smallest particle diameters are preferably approximately 0.1 μm and the largest particle diameters approximately 5 μm. Most particles have particle diameters in the range of 1 to 2 μm. This means that the particles essentially maintain the particle sizes of the polymer mixtures on which they are based and essentially do not agglomerate into larger particles. The particles obtained by the process according to the invention are preferably spherical and have an essentially smooth surface. Their density corresponds approximately to that of the polymers on which they are based.

The process according to the invention is characterized in particular by the fact that a wide range of different thermoplastic polymers can be processed with simple technical means into fine powders with a narrow particle size distribution.

The powders obtainable by the process according to the invention can be used to prepare dispersions, e.g. for coating purposes. For this purpose, the powders are dispersed in a non-solvent, preferably water.

The aqueous dispersions usually contain

5 to 50% by weight, preferably from 10 to 30% by weight, of powder. In addition to the powder, the aqueous dispersions can also be others 21

Dispersed plastics, included. Preferred plastics are fluorine-containing olefin polymers, in particular polytetrafluoroethylene. In addition, it is possible to add dispersion aids such as polyvinyl alcohol or glycerol to the dispersions. The dispersions can also contain flow aids and pigments. The dispersion can, for example, be sprayed or spread onto the surface. Such coatings serve e.g. to reduce the adhesive properties of the surface, such as metal. 10

Examples

example 1

15 50 vol .-% of a polyarylene ether ketone, with predominant

Structural units of formula I ₆ and a viscosity number of 100 ml / g (measured in 0.5 wt -.% Solution of 96 wt -.% Sulfuric acid Ultrapek ^® A 1000, BASF) were mixed with 50% by volume of a polyarylene ether sulfone Structural units according to formula I ₂ and

20 a viscosity number of 56 ml / g (. Measured weight in 1 -% solution of a mixture of phenol and 1, 2 -dichlorobenzene in weight in the weight volume of 1: 1, Ultrason ^® S 2010, BASF) in an extruder (ZKS 30 from Werner & Pfleiderer) with a shear rate of 200 to 4000 Hz. Then the

25 mixture cooled and granulated.

500 g of the blend were mixed with 1000 ml of tetrahydrofuran (THF), a dispersion of the polyarylene ether ketone in the solution of the polyarylene ether sulfone in THF being obtained. The polyarylene ether ketone powder was separated off by means of a centrifuge and then washed with THF. The average particle diameter was 7 μm. 25 μm was measured as the maximum grain size.

Example 2

35

50 vol .-% of a polyoxymethylene, with predominant structural units CH ₂ -0- and a melt volume rate of 7.5 ml / 10, (measured at 190 ° C and a load of 2.16 kg, Ultraform ^® N 2320, BASF) with 50% by volume of a polyethylene glycol

40 a molecular weight (weight average M _w ) of 35,000 g / mol

(Polyethylene glycol 35,000 S, Hoechst) mixed in an extruder (ZKS 30, Werner & Pfleiderer) at a shear rate of 200 to 4000 Hz. The mixture was then cooled and granulated. 5 22

500 g of the blend were mixed with 1000 ml of water, a dispersion of the polyoxymethylene in the solution of the polyethylene glycol in water being obtained. The polyoxymethylene powder was separated off by means of a centrifuge and then washed with water. The average particle diameter was 9.5 μm. The maximum grain size was measured to be 31 μm. Example 3

. 65 Vol .-% of a polyarylene ether sulfone, containing structural units according to formula I and a viscosity number of 56 ml / g (measured in 1 wt -% solution of a mixture of phenol and 1,2-dichlorobenzene in a weight ratio 1: 1 Ultrason ^® S 2010, BASF) with 35% by volume of a polycarbonate based on bisphenol A and a viscosity number of 61.6 ml / g (measured in 0.5% by weight solution of dichloromethane Lexan ^® 161) in an extruder ( ZKS 30, from Werner & Pfleiderer) with a shear rate of 200 to 4000 Hz. The mixture was then cooled and granulated.

500 g of the blend were mixed with 1000 ml of 10% strength by weight sodium hydroxide solution in water, a dispersion of the polyarylene ether sulfone in the solution of the polycarbonate in the base being obtained. The polyarylene ether sulfone powder was separated off by means of a centrifuge and then washed neutral with water. The average particle diameter was 6.5 μm. The maximum grain size was measured to be 24 μm.

Claims

23 patent claims

1. A process for the preparation of powders of thermoplastic polymers, characterized in that in a first step the melt of a thermoplastic polymer A is mixed with a polymer B which is incompatible with A, in a second step a dispersion of the polymer A from the mixture in a solution of polymer B in a solvent and then isolating the powder from the dispersion.

2. The method according to claim 1, characterized in that the polymer A used is a polyarylene ether, polyarylene sulfide, polyimide, polyamide, polyoximethylene, syndiotactic polystyrene, polyester or a mixture of two or more of the said polymers.

3. The method according to claim 1 or 2, characterized in that a water-soluble polymer is used as polymer B.

4. The method according to claim 1 or 2, characterized in that a polyarylene ether sulfone is used as polymer A and a polycarbonate as polymer B.

5. Powder thermoplastic polymer, obtainable by a process according to claims 1 to 4.

6. Use of the powder according to claim 5 for the production of dispersions.

7. Dispersions containing powder according to claim 5.

8. Use of the dispersions according to claim 7 for the production of coatings.