HK1144584A - Polyphenylene sulfide (per)fluoropolymer materials and process for preparation and use thereof - Google Patents

Description

Polyphenylene Sulfide (PPS) perfluoropolymer material and preparation method and application thereof

Technical Field

The present invention relates to the field of chemistry and to polyphenylene sulfide perfluoropolymer materials and a process for their preparation, which are used, for example, as friction materials for sliding bearings, gears, or as materials to be subjected to frictional loads in aviation and space travel, in the automotive field (for example for ball bearing housings in links) and in the technology of components with high requirements (for example as ball bearing cages) and as sports goods running surfaces to be subjected to frictional loads.

Background

Polyphenylene Sulfide (PPS), a high performance material, is provided in a commercially modified form with various fillers and reinforcing materials. According to the prior art, in filled and reinforced PPS, the filler and reinforcing material are physically embedded in a PPS-polymer matrix.

Perfluoropolymers such as Polytetrafluoroethylene (PTFE) and copolymers of tetrafluoroethylene and hexafluoropropylene (FEP) are known to have exceptional tribological properties.

In the known PTFE modification process, chemical activation of PTFE is achieved using (1) sodium amide in liquid ammonia and (2) a metal organic compound in an aprotic solvent. By means of said modification, improved interfacial interactions can be achieved reactively or only by means of adsorption forces.

Further, as a method, there are known: radiation chemical modification of perfluoropolymers in the absence or presence of agents such as (atmospheric) oxygen; and/or plasma chemical modification of perfluoropolymers, and thermo-mechanical degradation of PTFE are well known methods [ a. heger et al, Technologie der Strahlenchemie an polymer, akadeie-Verlag Berlin 1990; PTFE-Mikropulver TF9205, Dyneon ].

It is also known to modify or functionalize PTFE particles by grafting monomers or coupling with polymers (US 5,576,106, DE 19823609 A1, DE 10351813 A1, DE 10351814 A1). Since the melt temperature during thermoplastic (further) processing of PPS, for example by extrusion, or during molding of PPS is > 300 ℃, known PTFE modifications having functional groups and/or polymers grafted with aliphatic compounds cannot be used for coupling with PPS under melt processing conditions on the basis of the known low thermal stability of aliphatic compounds.

The compatibility of PPS with PTFE (within the framework of the present invention, this compatibility is to be understood as chemical coupling) has not been described to date.

Disclosure of Invention

The object of the present invention is to provide polyphenylene sulfide (per) fluoropolymer materials having improved friction properties, and to provide a simple and cost-effective production method and use thereof.

This object is achieved by the invention specified in the claims. Advantageous embodiments are the subject matter of the dependent claims.

The polyphenylene sulfide perfluoropolymer material according to the present invention consists of a material prepared by melt modification, which consists of a polyphenylene sulfide polymer matrix (PPS polymer matrix) having a modified perfluoropolymer (poly) dispersed therein, wherein the modification of the perfluoropolymer is achieved by functional groups and the modified perfluoropolymer particles are present in a manner bonded to the PPS polymer matrix by chemical coupling, wherein the chemical coupling is carried out by reaction with already existing functional, reactive groups of the perfluoropolymer during melt modification and/or by reaction with functional groups generated during melt modification consisting of stable (durable) perfluorocarbon (peroxy) radicals of the perfluoropolymer and/or by reaction with functional groups of the perfluoropolymer present during melt modification, The reaction of the (reactive) reactive groups effects chemical coupling.

Advantageously, the perfluoropolymer is present in a manner to chemically couple to the PPS polymer matrix through thioether and/or thioester linkages.

It is also advantageous if linear and/or branched polymers are present as PPS matrix.

Also advantageously present as perfluoropolymers are: polytetrafluoroethylene (PTFE) and/or copolymers of tetrafluoroethylene and hexafluoropropylene (FEP) and/or copolymers of Ethylene and Tetrafluoroethylene (ETFE) and/or Polychlorotrifluoroethylene (PCTFE) and/or copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ethers (TFA or PFA).

And it is also advantageous that the chemically coupled perfluoropolymer, which acts as a nucleating agent/nucleating agent, is present in a finely distributed manner in the PPS polymer matrix.

In the process according to the invention for the preparation of polyphenylene sulfide perfluoropolymer materials, polyphenylene sulfide having thiol groups and/or thiol ester groups is reactively compounded in the melt in one or more stages with one or more modified perfluoropolymer (micro/nano) powders, wherein further thermoplastic polymers or thermosetting (high-performance) polymers and/or fillers and/or reinforcing materials and/or additives can be added.

It is advantageous to use modified perfluoropolymer powders having ethylenically unsaturated groups and/or having carboxylic acid groups and/or carboxylic acid esters and/or carboxylic acid halide groups, preferably also modified perfluoropolymer powders having perfluoroalkylene groups or carboxylic acid halide groups in the form of carboxylic acid fluoride groups.

It is also advantageous to use modified perfluoropolymer powders having stable (durable) perfluorocarbon (peroxy) radicals, which have been prepared by radiation chemical modification of perfluoropolymer (micro/nano) powder particles under oxygen flow conditions, and also to use modified perfluoropolymer powders having stable (durable) perfluorocarbon (peroxy) radicals.

In addition, perfluoropolymers having thermally labile functional groups are advantageously used.

And also advantageously used as modified perfluoropolymer (micro/nano) powder are: polytetrafluoroethylene (PTFE) and/or copolymers of tetrafluoroethylene and hexafluoropropylene (FEP) and/or copolymers of Ethylene and Tetrafluoroethylene (ETFE) and/or Polychlorotrifluoroethylene (PCTFE) and/or tetrafluoroethylene and perfluoroalkyl vinyl ether (TFA or PFA), wherein it is also advantageous to use as modified perfluoropolymer (micro/nano) powder PTFE which is chemically degraded by irradiation and more advantageously to irradiate the chemically degraded PTFE under a stream of oxygen.

It is also advantageous to use as the PTFE that is degraded chemically by irradiation with at least 20 kilograys (kGy), more preferably at least 100kGy, and modified PTFE.

It is also advantageous to use thermally/thermo-mechanically modified perfluoropolymer (micro/nano) powder particles as modified perfluoropolymer (micro/nano) powder.

It is also advantageous to use PPS in the form of linear and/or branched chains with reactive thiol groups and/or thiol ester groups.

It is also advantageous to use a PPS polymer having a small amount of thiol groups and/or thiol ester groups and a PPS polymer rich in thiol groups and/or thiol ester groups, the ratio of the PPS polymer having a small amount of thiol groups and/or thiol ester groups to the PPS polymer rich in thiol groups and/or thiol ester groups being from 99: 1 to 1: 99.

It is also advantageous to use PPS polymers having less than or equal to 1% of thiol groups at the ends of the PPS chains as PPS polymers having a small number of thiol groups and/or thiolate groups.

It is also preferred to use PPS polymers having > 1% of thiol groups in the PPS segments as PPS polymers having a large number of thiol groups and/or thiol ester groups.

It is also advantageous to use modified perfluoropolymer (micro/nano) powder particles in an amount of 1 to 99 mass%, still preferably 5 to 50 mass%, more preferably 10 to 30 mass% of the PPS polymer.

It is also advantageous to add further thermoplastic or thermosetting (high-performance) polymers and/or fillers and/or reinforcing materials before, during or after the reactive compounding.

It is also advantageous to carry out the reactive compounding in a melt mixer and/or in a kneader (Kneter) and/or in a twin-screw or multi-screw extruder and/or in a planetary roll extruder (planetwalzexter).

It is also advantageous to conduct the reactive compounding at a melt processing temperature that is at least equal to or greater than the melt temperature of the PPS material.

Advantageously, the reactive compounding is conducted at a melt processing temperature that is at least equal to or greater than the melt temperature of the perfluoropolymer material.

It is also advantageous to carry out a further reactive transformation during and/or after the reactive combination.

It is also advantageous to add the modified perfluoropolymer (micro/nano) powder to the melt at one or more addition points during compounding.

It is also advantageous to use a modified perfluoropolymer (micro/nano) powder as a mixture of unmodified and modified perfluoropolymer.

The polyphenylene sulfide perfluoropolymer material provided by the invention has the following applications: as a compacting substance (kompaktubstanz) and/or as an additional component/component part of a sliding bearing and/or in an oleophobic and/or hydrophobic or component material/compacting material formulated therefrom and/or in a shaped part and/or as a surface-modifying component in a (slip) film and/or as a coating and/or in a (slip) foil and/or as a blending component (Blendkomponent) and/or as an additive.

Advantageously, polyphenylene sulfide perfluoropolymer is used for further processing into thermoplastic melts and/or into reactive materials and/or into dispersions.

It is possible by the above invention that a chemically coupled polyphenylene sulfide perfluoropolymer material having a stable processing morphology and a finely distributed perfluoropolymer component in the PPS matrix component can be provided by a reactive transition in the melt, which can be processed into a member having a sliding friction coefficient comparable to PTFE and having a low wear coefficient. The member has a longer life.

The compound consisting of PPS and perfluoropolymer according to the present invention is obtained by reactive transformation in, for example, a melt mixer. The modified perfluoropolymer component is then not only present in a homogeneous distribution within the PPS matrix, but is also rendered compatible with, i.e., chemically coupled to, the PPS matrix component by chemical coupling. This gives the material according to the invention advantageous properties.

The proof of chemical coupling (nachwei) is carried out by separating the unbound PPS matrix components from the undissolved perfluoropolymer components, whereby, according to the invention, no pure perfluoropolymer is obtained anymore, but instead a perfluoropolymer product is obtained having PPS polymer chains chemically coupled at the surface and modified after the separation process.

By processing PPS matrix materials using modified perfluoropolymer (micro/nano) powders, it is possible to directly prepare homogeneously dispersed compounds in which, unlike what has been known so far: the perfluoropolymer component is only present in-line as a second component that is not dissolved and compatible. According to the invention, the perfluoropolymer component interacts directly with the PPS matrix polymer via covalently bonded PPS polymer chains, whereby a homogeneous distribution and a stable processing morphology are achieved. By mechanical forces, for example under sliding friction conditions, the perfluoropolymer particles can no longer be easily ground out of the matrix material by chemical bonding through the PPS polymer chains (heraustreiben), in contrast to physical mixtures and inserts.

In addition to the concentration of reactive groups on the PPS and on the perfluoropolymer (micron/nanometer) powder, the melt processing conditions also have a significant impact on the coupling reaction, since the reactive groups can only react in direct contact with each other. Therefore, it is desirable to achieve as good a thorough mixing of the reaction components as possible.

On PPSThe reactive groups of (a) are thiol groups and/or thiol ester groups of the linear or branched PPS polymer, which are preferably present as end groups. The reactive groups in the perfluoropolymer are ethylenically unsaturated double bonds that enable addition with thiol and/or thiolate groups in the PPS. In addition, during the reactive transition in the melt, the melt processing conditions are adjusted in such a way that the reactive olefinic double bonds are formed in the perfluoropolymer component by elimination/elimination reactions. For this purpose, hydrogen halides and preferably hydrogen fluoride are decomposed (abspalatene), and/or the existing carboxylic acid groups are decomposed to CO₂In the case of (a) the reaction is carried out with simultaneous or subsequent elimination of hydrogen fluoride, and the reactive coupling centers are thus formed in situ.

Another coupling reaction is the reaction of thiol and/or thiolate groups on the PPS with carbonyl fluoride groups on the perfluoropolymer, generated, for example, during radiation modification with electron beam and/or gamma rays (gammaastrahlen) in the presence of oxygen.

Another possibility is that the stable/durable perfluoro (peroxy) radical centers in the perfluoropolymer are converted into reactive coupling groups in the melt/under melt processing conditions, wherein it cannot be excluded that said radicals react directly with PPS in the coupling case.

The stable/durable perfluoro (peroxy) radical centers in the perfluoropolymer are generated during the polymerization of the perfluoropolymer or may additionally be generated by radiation chemical modification and/or plasma chemical modification of the perfluoropolymer.

In general, in the polyphenylene sulfide perfluoropolymer material according to the present invention, the perfluoropolymer particles are compatible with the PPS matrix by chemical bonding, i.e., become compatible with each other.

In the preparation of the polyphenylene sulfide perfluoropolymer material according to the invention, i.e. during melt processing of the perfluoropolymer particles with polyphenylene sulfide, sufficient splitting and sufficient mixing of the starting materials is achieved by shearing of a corresponding magnitude, so that the functional groups of the perfluoropolymer particles, which are largely spatially masked by the perfluoropolymer chains, are exposed. The already existing functional groups and/or the resulting functional groups of the perfluoropolymer and/or the stable (durable) perfluorocarbon (per) radicals are brought into direct contact with the functional groups of the polyphenylene sulfide by said measures. The perfluoropolymer (particles) can be chemically bonded/coupled to the polyphenylene sulfide only in direct contact with each other.

The perfluoropolymer (micron/nanometer) powder may be either melted with the PPS components or added directly to the PPS melt. Surprisingly, the material according to the invention is produced directly in a melt reaction, wherein advantageously a material which can be processed further is obtained directly.

The reactive transformation in the melt is carried out at the PPS processing temperature. For the preparation of the material according to the invention, all PPS material in pure form and/or filled PPS material and/or reinforced PPS material can be used. Likewise, other polymers may be added. The materials may be used as a starting mixture and/or added during melt processing and/or in a subsequent step such as formulation formation. The preparation process can be carried out as a one-stage or multi-stage process.

The material produced can be used as a compact substance and/or as an additional component/component part of a plain bearing and/or as an oleophobic and/or in a hydrophobic or component material/compact material formulated therefrom and/or in a shaped part and/or as a surface-modifying component, for example in a sliding film or a sliding foil, and/or as a coating and/or as a blending component and/or as an additive, for example in a sliding lacquer (gleitback).

Detailed Description

The invention will be illustrated in detail below by means of a number of specific examples.

Example 1

In a twin-screw extruder ZSK30(Werner & Pfleiderer), X kg/h of PPS (Fortron series, Ticona (Fortron, Ticona)) and Y kg/h of PTFE (see Table 1) were added to the funnel. The twin-screw extruder was operated with the temperature profile and rotational speed of 200U/min as listed below. The melt strand was granulated after cooling in a water bath.

The material obtained was further processed into semi-finished products and samples by die casting. Samples were made from the materials and the following properties were determined on the samples.

Table 1: parameters for the preparation of PPS + PTFE-cg material

ZSK-30-41L/D

Processing temperature: 290, 330, 300, 280-D: 270 deg.C

Rotating speed: 200rpm

Throughput of materials: 8 kg/h material, PPS, Natural, (Fortron series, Ticona company (Fortron, Ticona)) are given in the following Table

2x aeration/degassing, granulation nozzle, water bath cooling, and granulator

Test of	Material	X kg/hr PPS (Natural, Ticona)	Y kg/hr PTFE
				PPS1	PPS+20TF2025(500)-cg	6.4 kg/hr PPS Fortron 0205P4	1.6 kg/h TF2025 (Electron irradiation at 500 kGy)
PPS2	PPS+30TF2025(500)-cg	5.6 kg/hr PPS Fortron 0205P4	2.4 kg/h TF2025 (Electron irradiation at 500 kGy)

Test of	Material	X kg/hr PPS (Natural, Ticona)	Y kg/hr PTFE
				PPS3	PPS+20TF9205-cg	6.4 kg/hr PPS Fortron 0205P4	1.6 kg/h TF9205

cg.. chemical coupling/compatibility

TF2025 and tf9205

The material characteristic values from the physical examination are described in table 2. Despite the addition of "soft" PTFE, on the order of 20 and 30 mass%, the resulting material had only a slight decrease in the E-modulus value. The tensile strength values also show similar behavior. The values of impact strength and notched impact strength are surprising. By chemical coupling/compatibilization, PTFE does not act as an impurity, but rather as an impact modifier.

Table 2: mechanical characteristics of the PPS Material or of the PPS + PTFE-cg-Material (measured approximately 240 hours after the preparation of the sample)

Test of	Material	Et[GPa]	σM[MPa]	εM[％]	σB[MPa]	εB[％]	acU[kJ/m2]	acA[kJ/m2]
									PPS 0	PPS bagged material (control)	3.73	61.2	1.7	60.5	1.7	21.8	2.3
PPS 1	PPS+20TF2025(500)-cg	3.40	56.1	2.0	55.4	2.0	25.3	3.3
									PPS 2	PPS+20TF2025(500)-cg	3.03	50.6	2.5	50.5	2.5	20.6	3.0
PPS 3	PPS+20TF9205-cg	3.35	53.0	2.0	52.0	2.0	27.5	3.1

The friction characteristics of the PPS + PTFE-cg-material have a sliding friction behavior similar to that of PTFE. Compared with pure PPS, the abrasion value is reduced to 27 to 30% when 20 mass% of PTFE is added, and the abrasion value is reduced to 18 to 21% when 30 mass% of PTFE is added.

Claims (17)

1. Polyphenylene sulfide perfluoropolymer material consisting of a material prepared by melt modification consisting of a polyphenylene sulfide polymer matrix (PPS polymer matrix) with a modified perfluoropolymer (poly) dispersed therein, wherein the modification of the perfluoropolymer is achieved with functional groups and the modified perfluoropolymer particles are present bonded to the PPS polymer matrix by chemical coupling, wherein the chemical coupling is performed by reaction with functional, reactive groups of the already present perfluoropolymer during melt modification and/or by reaction with functional groups generated during melt modification consisting of stable (durable) perfluorocarbon (peroxy) radicals of the perfluoropolymer, and/or by reaction with perfluoropolymer functional (reactive) reactive groups generated during melt modification.

2. The material of claim 1, wherein the perfluoropolymer is present in a manner that is chemically coupled to the PPS polymer matrix through one or more thioether and/or thioester linkages.

3. The material of claim 1, wherein the linear and/or branched polymer is present as a PPS matrix.

4. Material according to claim 1, wherein Polytetrafluoroethylene (PTFE) and/or copolymers of tetrafluoroethylene with hexafluoropropylene (FEP) and/or copolymers of ethylene with tetrafluoroethylene (ETFE) and/or Polychlorotrifluoroethylene (PCTFE) and/or copolymers of tetrafluoroethylene with perfluoroalkyl vinyl ethers (TFA or PFA) are present as perfluoropolymers.

5. The material of claim 1, wherein the chemically coupled perfluoropolymer functions and exists in a finely distributed manner as a nucleating agent/nucleation former in the PPS polymer matrix.

6. Process for the preparation of polyphenylene sulfide perfluoropolymer materials, in which polyphenylene sulfide having thiol groups and/or thiol ester groups is reactively compounded in the melt in one or more stages with one or more modified perfluoropolymer (micro/nano) powders, wherein further thermoplastic polymers or thermosetting (high performance) polymers and/or fillers and/or reinforcing materials and/or additives can be added.

7. The process according to claim 6, wherein polyphenylene sulfide (PPS) is used which has reactive thiol groups and/or thiol ester groups in linear and/or branched form, and/or using a PPS polymer having a small amount of thiol groups and/or thiol ester groups and a PPS polymer rich in thiol groups and/or thiol ester groups, wherein the ratio of the PPS polymer containing a small amount of thiol groups and/or thiol ester groups to the PPS polymer rich in thiol groups and/or thiol ester groups is from 99: 1 to 1: 99, and/or use of PPS polymers having less than or equal to 1% of thiol groups in the PPS segments as PPS polymers having a small proportion of thiol groups and/or thiolate groups, or PPS polymers having > 1% of thiol groups in the PPS segments are used as PPS polymers having a high proportion of thiol groups and/or thiol ester groups.

8. Process according to claim 6, wherein modified perfluoropolymer (micro/nano) powders having ethylenically unsaturated groups and/or having carboxylic acid groups and/or carboxylic acid esters and/or carboxylic acid halide groups, preferably in the form of carboxylic acid fluorides and/or having perfluoroalkylene groups and/or having stable (durable) perfluorocarbon (per-oxygen) radicals are used, said modified perfluoropolymer (micro/nano) powders preferably having been prepared by the radiation chemical modification of perfluoropolymer (micro/nano) powder particles under oxygen flow conditions; and/or the use of perfluoropolymers with thermally labile functional groups, and/or Polytetrafluoroethylene (PTFE) and/or copolymers of tetrafluoroethylene with hexafluoropropylene (FEP) and/or copolymers of ethylene with tetrafluoroethylene (ETFE) and/or Polychlorotrifluoroethylene (PCTFE) and/or copolymers of tetrafluoroethylene with perfluoroalkyl vinyl ethers (TFA or PFA) and/or thermally modified/thermomechanically modified perfluoropolymer (micron/nanometer) powders, which are reactively compounded in the melt in one or more stages, wherein further thermoplastic or thermosetting (high-performance) polymers and/or fillers and/or reinforcing materials and/or additives can be added.

9. Process according to claim 6, wherein as modified perfluoropolymer (micro/nano) powder is used a chemically degraded PTFE by irradiation, preferably under a stream of oxygen and/or a chemically degraded and modified PTFE preferably irradiated in at least 20kGy, more preferably in at least 100 kGy.

10. The process according to claim 6, wherein 1 to 99 mass%, preferably 5 to 50 mass%, more preferably 10 to 30 mass% of modified perfluoropolymer (micro/nano) powder particles of the PPS polymer are used.

11. The method according to claim 6, wherein further thermoplastic or thermosetting (high performance) polymers and/or fillers and/or reinforcing materials are added before, during or after the reactive compounding.

12. The process according to claim 6, wherein the reactive compounding is carried out in a melt mixer and/or in a kneader and/or in a twin-screw or multi-screw extruder and/or in a planetary roll extruder.

13. The method of claim 6, wherein the reactive compounding is performed at a melt processing temperature at least equal to or greater than a melt temperature of the PPS material and/or the perfluoropolymer material.

14. The method of claim 6, wherein a further reactive transformation is performed during and/or after the reactive combination.

15. The process of claim 6, wherein the modified perfluoropolymer (micro/nano) powder is added to the melt at one or more feed points during compounding.

16. The process according to claim 6, wherein the modified perfluoropolymer (micro/nano) powder is used as a mixture of unmodified perfluoropolymer and modified perfluoropolymer.

17. Use of the polyphenylene sulfide perfluoropolymer material according to one of claims 1 to 5 and prepared according to one of claims 6 to 16: as a compact substance and/or as an additional component/component part of a sliding bearing and/or as an oleophobic and/or hydrophobic or component material/compact material formulated therefrom and/or in a shaped part and/or as a surface-modifying component in a (slip) film or as a coating and/or in a (slip) foil and/or as a tempering component and/or as an additive, preferably for further processing into a thermoplastic melt and/or reactive material and/or dispersion.