阅读说明：本技术 聚酮化合物 (Polyketides ) 是由 B·赫尔巴赫 M·萨特 R·菲茨 T·斯查伯 于 2019-10-02 设计创作，主要内容包括：本发明涉及一种脂肪族聚酮化合物,其包含85.0重量％至99.5重量％的脂肪族聚酮和0.5重量％至15.0重量％的超高分子量聚乙烯。(The present invention relates to an aliphatic polyketone compound comprising 85.0 to 99.5 wt.% of an aliphatic polyketone and 0.5 to 15.0 wt.% of an ultra high molecular weight polyethylene.)

1. An aliphatic polyketone compound comprising 85.0 to 99.5 wt.% aliphatic polyketone and 0.5 to 15.0 wt.% ultra high molecular weight polyethylene.

2. Aliphatic polyketone according to claim 1, characterized in that the proportion of ultra high molecular weight polyethylene is 2.0 to 8.0 wt.%, and in particular 5.0 to 7.5 wt.%.

3. Aliphatic polyketone according to claim 1 or 2, wherein the ultra high molecular weight polyethylene has a molecular weight of more than 100 ten thousand g/mol, preferably 300 to 700 ten thousand g/mol.

4. Aliphatic polyketone according to one or more of the preceding claims, wherein the average particle size of the ultra high molecular weight polyethylene is in the range of 10 to 300 μm.

5. Aliphatic polyketone according to one or more of the preceding claims, characterized in that the aliphatic polyketone has a temperature of 210 to 230 ℃ measured according to DIN EN11357-1 methodMelting point, and/or glass transition point of 5 ℃ to 20 ℃, and/or 1.1 to 1.3g/cm³(particularly 1.24 g/cm)³) Density in the range, and/or moisture absorption of 0.3 to 1.2%, and/or 2 to 80cm³MVR in the range of 10 min.

6. Aliphatic polyketone according to one or more of the preceding claims, characterized in that the aliphatic polyketone is a terpolymer.

7. Aliphatic polyketone according to one or more of the preceding claims, characterized in that the aliphatic polyketone is prepared from ethylene, carbon monoxide and an olefin having 3 to 5 carbon atoms, preferably propylene.

8. Aliphatic polyketone according to one or more of the preceding claims, characterized in that during its preparation the carbon monoxide and the olefin are arranged in a strictly alternating fashion in the polymer chain.

9. Aliphatic polyketone according to one or more of the preceding claims, characterized in that the aliphatic polyketone has an average molecular weight Mn (number average molecular weight) between 60000 and 100000 and/or an Mw (weight average molecular weight) between 132000 and 320000, the polydispersity index preferably being between 2.2 and 3.2.

10. A process for preparing an aliphatic polyketone compound, the process comprising blending 99.5 to 85.0 wt% of an aliphatic polyketone with 0.5 to 15 wt% of an ultra high molecular weight polyethylene.

11. Shaped body, in particular a seal, a peeling element, a coupling element, a support ring (anti-extrusion ring), a wear strip, a guide and a structural component, characterized in that the shaped body comprises an aliphatic polyketone compound according to one or more of the preceding claims.

12. The molded body according to claim 11, wherein the molded body is a rotationally symmetrical molded body.

13. Shaped body according to claim 11 or 12, characterized in that the shaped body is produced by an injection molding process, in particular by an injection molding process using only one injection point.

14. Use of aliphatic polyketones according to one or more of claims 1 to 9 for the preparation of shaped bodies, preferably rotationally symmetrical shaped bodies, in particular seals (e.g. rod and/or piston seals), structural parts (with and/or without sealing function), peeling elements, coupling elements, gears, sliding bearings, bearing rings (in particular anti-extrusion rings), wear strips and/or guides.

15. Use according to claim 14, characterized in that the shaped body is produced by an injection molding process, in particular by an injection molding process using only one injection point.

Technical Field

The present invention relates to polyketides based on aliphatic polyketones, in particular polyketides with improved tribological properties. The invention also relates to a method for producing polyketides, to the use thereof for producing shaped bodies, in particular seals, and to shaped bodies containing polyketides.

Background

Aliphatic polyketones are linear polymers prepared from carbon monoxide and an alpha-olefin in which the monomer units are arranged in strictly alternating fashion in the polymer chain.

Such polymers were first mentioned in the works of Merlin m. brubaker, working in dupont in Walter Reppe of 1940 and in the 50 th 20 th century, carbon monoxide was interpolymerized to unsaturated species such as aliphatic mono-olefins and ethylene fluorides (e.g., US 2.495.286). The large-scale synthesis of aliphatic polyketones was developed, optimized and patented by the staff of Shell oil company in the last thirty years of the twentieth century under the heading of Eit Drent (for example US 3,689,460; US4,818,810; US4,921,937). The polymerization can be carried out in methanol suspension or by gas phase reaction with an immobilized catalyst (e.g., Drent, E.; Mul, W.P.; Smardijk, A.A. (2001); "polyketone"; encyclopedia of Polymer science and technology, and Bianchini, C. (2002); alternating copolymerization of carbon monoxide and olefins with a single-site metal catalyst; coord. chem. Rev.225: 35-66). Palladium (II) complexes are mainly used as catalysts or precursors thereof (e.g. U.S. Pat. No. 3,689,460; U.S. Pat. No. 3,694,412; U.S. Pat. No. 4,818,810; Sen, A.; Lai, T.W. (1982); novel palladium (II) catalyzed copolymerization of carbon monoxide with olefins; J.Am.chem.Soc.104(12): 3520-. Maurice Brookhart, exemplified by palladium (II) phenanthroline catalysts, describes the mechanism of palladium catalysis in methanol suspension (Rix, F.C.; Brookhart, M.; White, P.S. (1996) "mechanism study of palladium (II) -catalyzed copolymerization of ethylene and carbon monoxide"; J.Am.chem.Soc.118(20): 4746-.

Aliphatic polyketones were first sold commercially in 1996 and can be sold under the trade name from ShellAnd (4) purchasing in large quantities. In 2003, aliphatic polyketones were studied by Xiaoxing, Korea (e.g., US 7,803,897). Since 2015, Xiaoxing has a semi-continuous factory production trade name of 50,000 tons annual capacityAliphatic polyketones of (a).

Xiaoxing currently produces almost exclusively polyketone terpolymers, not the traditional polyketone copolymers made only from carbon monoxide and ethylene (figure 1). These polyketone terpolymers are made from carbon monoxide, ethylene and preferably a small amount of propylene.

In some cases, longer chain alpha olefins (e.g., 1-butene) may also be used as trimerizing monomers.

The reason for using a terpolymer rather than a copolymer is that the brittleness of the terpolymer is significantly reduced. Because the strictly alternating polymer chains of polyketone copolymers of carbon monoxide and ethylene have a very low defect rate (one defect per million monomer units; see Rix, F.C., Brookhart, M., White, P.S (1996) "mechanistic study of palladium (II) -catalyzed copolymerization of ethylene and carbon monoxide"; J.Am.chem.Soc.118(20):4746-4764) and a large number of polar ketone groups, the polyketone copolymers are highly crystalline, very hard but also very brittle, which greatly limits their potential for use as polymeric materials. By adding a small amount of propylene (about 5%) during the synthesis, the crystallinity can be disturbed, lowering the melting point of 255 ℃ (copolymer of carbon monoxide and ethylene) to 220 ℃ (terpolymer), resulting in a very tough rather than brittle polymer.

Aliphatic polyketone terpolymers have a crystallinity of about 30% and are characterized by good mechanical properties, which are substantially unaffected by moisture compared to, for example, polyamides. The tensile modulus of elasticity of the unmodified polyketones is about 1400 to 1500MPa according to ISO 527-1/2. According to ISO 527-1/2, the elongation at yield is approximately 25%, which can withstand more deformation cycles up to the yield point without plastic deformation than other engineering plastics. In addition, it exhibits ductility over a wide temperature range, and elongation at break of over 300% can be achieved. According to ISO 179-1/1EU standard, the Charpy impact strength of unfilled, unmodified polyketone terpolymers is sufficiently high that no fracture occurs at 23 ℃ nor at-30 ℃. According to ISO 179-1/1eA, the Charpy notched impact strength depends on the polymer chain length and is from 10 to 15KJ/m at a temperature of 23 DEG C²At a temperature of-30 ℃ of 3.5 to 4.5KJ/m²。

Further, aliphatic polyketones have excellent chemical resistance, particularly against nonpolar solvents such as aliphatic or aromatic hydrocarbons. Aliphatic polyketones also have very good resistance to water or dilute bases and acids. For example, a test stored in water at 80 ℃ for 25 days showed only a 2.5% weight increase in weight and a 1.3MPa increase in yield stress. The product is stored in 1% hydrochloric acid or 1% sodium hydroxide solution at 80 deg.C for 25 days without any deterioration of mechanical properties. Only strong acids or bases can cause degradation of the aliphatic polyketones over time.

Aliphatic polyketones of Xiaoxing are further refined by various complexing agents and are available under various trade names, e.g.PK (AKRO-PLASTIC GmbH Co.),(A.Schulman GmbH), WITCOM PK (Witcom Engineering Plastics B.V. Co.) or(Sustaplast SE&Kg company) are commercially available. Selected properties of the aliphatic polyketones can be further improved or modified by compounding with certain additives. For example, chopped with glass fibers (e.g., in commercial products)PK-VM GF15、PK-VM GF30、PK-VM GF50、GF15、GF30、Ketoprix^TMEKT33G2P、Ketoprix^TMEKT33G2P, etc.) or chopped carbon fibers (e.g., in commercial products)PK-HM CF12 black,PK TRM CF20 black, etc.) and flame retardant finishes (e.g., in commercial products)PK-VM GF20FR black,HV 4DE, etc.) stiffen the polymer.

The tribological properties of aliphatic polyketones are equally good, which makes them of particular interest in sealing applications. For example, Lvbek's science of applicationWas learned in a general tribometer (Pin plate, plate: 100Cr6, load: 2.5MPa, stroke: 1.8mm, R_a0.42, sliding movement: 46Hz) showed that aliphatic polyketones with an MVR of 60g/10min had a coefficient of friction of 0.33 and a coefficient of friction of 0.8 x 10⁶mm³Specific wear rate in Nm. In order to be able to meet the high demands on tribological properties, which are necessary for certain seals, for example, tribological additives must often also be used. When used, these additives form a separation film between the polymer surface and the mating surface, which film is capable of withstanding considerable forces during prolonged rolling or sliding contact. In commercial products, e.g. inPK-VM TM、PK-HM TM、Among PK TRM TF10, Witcom PK/3L1 and Witcom PK-3L3, almost only PTFE powder or PTFE powder/silicone oil combinations were found.

Another major advantage of aliphatic polyketones (copolymers and terpolymers) is that they can be thermoplastically processed.

In this context, it is desirable to use aliphatic polyketones for seals, because aliphatic polyketones, despite their hardness, have a certain elasticity and have a high resistance to extrusion and good tribological properties. They are particularly suitable for rotationally symmetrical elements, such as rod seals, piston seals and wipers, in particular as possible alternatives to rod and piston seals made of PTFE, PTFE bronze and PTFE glass fibers, since the latter cannot be produced by injection molding, as explained in more detail below. The conversion of the material from PTFE, PTFE bronze or PTFE glass fibers to an injectable aliphatic polyketone represents a great advantage in terms of production method, production time and production costs. The rod seal is mainly used in pneumatic and hydraulic cylinders and functions to seal the telescopic cylinder rod. The purpose is to prevent the escape of pressurized working medium from the cylinder. At the same time, it must be protected from external contamination (scrapers). On the other hand, the task of the piston seal is to seal the piston against the cylinder and ensure that it moves efficiently with minimal friction.

Currently, rod seals and piston seals are typically made of PTFE, PTFE bronze compounds, or PTFE fiberglass compounds, because these materials produce low friction and allow stick-slip free operation. However, due to its relatively high modulus of elasticity, the PTFE seal can no longer be entirely radially compressed between the rod or piston surface and the groove bottom. Instead, its contact pressure must first be generated by expanding the seal and then additionally enhanced by the elastomeric seal (typically an O-ring). O-rings, commonly referred to as tensioner rings, pressure elements or actuators, additionally serve as secondary seals. Because of the great resistance to compression of the PTFE sealing ring, it can also be used under high pressure without a support ring.

Although PTFE and modified PTFE are thermoplastics, they cannot be processed from the melt as other thermoplastics due to their very high molecular weight and high melt viscosity, but only by various pressing and sintering techniques. Therefore, a seal member made of PTFE or a PTFE compound is complexly manufactured according to the following method. Powdered polymer is pressed at room temperature into a preform, also referred to as a "green body". In this case, the loose powder deposit is compacted and compacted with a defined compaction pressure. The maximum pressing pressure depends on the nature of the powder and ranges from 150bar (for e.g. non-free-flowing S-PTFE types) to 800bar (for PTFE compounds). The pressing process is typically performed slowly, uniformly, and uninterruptedly. Once the maximum pressure is reached, it must be held for a certain time (pressure hold time) to allow the particles to flow and reduce internal stress peaks or irregularities. After a slow relaxation, the strut is preferably left unstressed for a certain time to further vent or balance the stress. After compaction, the compact is subjected to a specified sintering cycle. In this case, a defined and adapted heating of the pellets is carried out and finally a time-controlled sintering is carried out in a regulated sintering furnace at a maximum temperature of 370 to 380 ℃. After a crystalline melting point of above about 342 ℃, the PTFE transforms into an amorphous state and the pre-compacted powder particles sinter together to form a uniform structure. In particular for larger compacts, a slow passage through the melting temperature range is recommended, since here the volume of the material increases disproportionately and in some cases greater stresses occur. Despite the melting/gel point being reached or exceeded, the compacts are sintered so-called "free-form", since the gel stability of the PTFE is very high owing to the high molecular weight.

As can be seen from the previous description of seals made of PTFE or PTFE compounds, such as PTFE bronze, the manufacturing effort is very high and is associated with high costs.

The use of aliphatic polyketones for rotationally symmetrical seals, in particular for rod and piston seals, is therefore very advantageous, since these seals have excellent mechanical properties and can be processed by injection moulding processes (unlike the PTFE or PTFE compounds usually used).

However, practical tests have shown that this is not so easy to achieve. In fact, one of the basic criteria for a rotationally symmetric seal is its seam strength, as described below. Rod and piston seals made from aliphatic polyketone/PTFE compounds have comparable tribological properties and comparable leakage values as rod and piston seals made from PTFE, PTFE bronze or PTFE glass fibres, but the poor joint strength makes them unsuitable for use as rod or piston seals or similar rotationally symmetrical seals.

When using thermoplastic materials, the rotationally symmetrical seal is typically made by a plastic injection molding process. There are several ways to fill such rotationally symmetric cavities, such as a) ring runners or shield runners, B) point or tunnel gates or C) hot runner systems.

A disadvantage of the shield runner or annular runner (a) is that the runner geometry must be separated from the actual annular product by downstream operations, which incurs corresponding costs. Therefore, these runner variants are usually only used for efficient production in special cases.

Spot or tunnel gates (B) (gates) have been established as a more modern, economical manufacturing variant. Here, the plastic is usually allowed to enter the cavity through a single injection point. Products manufactured in this manner typically do not require any rework because the product is already separated from the runner geometry when it is ejected from the injection molding machine (ready to fall). So to speak, the runner will cut itself.

However, such laterally injected products usually have a so-called junction (seam) on the opposite side of the injection point, i.e. the point where the melt fronts meet. The seam may represent a weak point and lead to a predetermined breaking point in the plastic product. The degree of bonding of the product to the seam depends on such factors as injection pressure, melt and mold temperature, as well as on the choice of materials and the influence of additives.

In practical tests it was found that commercial PTFE-filled polyketones, for examplePK-VM TM、PK TRM TF10, Witcom PK/3L1, and Witcom PK-3L3 caused a significant reduction in the joint strength of injection molded seals, so even with only a small application of force, the parts broke at the joint, and were therefore less suitable for spot or tunnel casting processes. Application tests have also shown that polyketides filled with PTFE (e.g.PK-VM TM) break at the joint when installed into the cylinder because the rigid seal must be strongly deformed using assembly pliers.

For rod seals made from commercial Tribo-PK compounds, this deformation leads to fracture at the joint.

Disclosure of Invention

It is therefore an object of the present invention to provide a polyketone which can be processed by an injection molding process and which is characterized by a high seam strength. Furthermore, the polyketides should exhibit good tribological properties and high extrusion resistance required for sealing applications.

This object is achieved by an aliphatic polyketone compound comprising 85.0 to 99.5 wt.% of an aliphatic polyketone and 0.5 to 15.0 wt.% of an ultra high molecular weight polyethylene.

According to the invention, the term "compound" is understood in the conventional sense as a plastic comprising at least two polymers which are not blendable with one another, or as a plastic which, in addition to the polymers, also comprises fillers, reinforcing materials or other additives (for example tribological additives) which form a multiphase system with the polymers. The polyketone compound according to the present invention comprises aliphatic polyketone and ultrahigh molecular weight polyethylene, which are at least two polymers that are included and are not blendable with each other.

Rather, a blend has a combination of two or more polymers physically mixed (blended). The homogeneous blend has a single phase. The heterogeneous blend has at least two phases. Homogeneous blends no longer exhibit the properties of the individual polymers, but rather exhibit their own novel properties, which may differ significantly from those of the original polymers (see Kulshreshtha, A.K. (2002) "handbook of polymer blends and composites (volume 1)", iSmithers Rapra Publishing or specling, L.H. (2005) "introduction to polymer physics science", John Wiley & Sons.).

According to the present invention, it was found that by blending 0.5 to 15 wt% of ultra high molecular weight polyethylene into an aliphatic polyketone, the tribological properties in terms of friction and wear can be improved such that it is comparable to that of commercially available tribologically modified polyketones, but at the same time has significantly better seam strength and high crush resistance.

As mentioned above, the improved seam strength of the polyketone compounds of the invention is of great advantage compared to commercially available PTFE tribologically modified aliphatic polyketones, since it enables, for example, the production of seals by modern and inexpensive variants of injection molding processes using only one injection point. The resulting product is characterized by high resistance to extrusion. This is particularly advantageous for dynamic sealing applications because otherwise pinch marks may form during the life of the seal, resulting in seal leakage or premature failure. At the same time, the aliphatic polyketones according to the invention have properties which are similar to the sliding and friction properties of PTFE, PTFE/bronze compounds or commercially available PTFE tribologically modified polyketones. Surprisingly, it was found that 0.5 to 15 wt.%, more preferably 2.0 to 8.0 wt.%, in particular 5.0 to 7.5 wt.% of ultra-high molecular weight polyethylene, each based on the total weight of the polyketone compound, is already sufficient to keep up with the sliding and friction properties of an aliphatic polyketone filled with 20 wt.% PTFE. It is also surprising that the aliphatic polyketones of the present invention do not break apart when subjected to deformation stresses, such as occurs when a rigid piston seal is installed in a piston cavity using assembly pliers, whereas a seal of the same design made from a commercial polyketone modified with 20 wt% PTFE breaks at the joint in 75 to 90% of the installation tests. The improved seam strength can presumably be explained by a lower proportion of tribological additives of 5 to 19.5% by weight, preferably 12 to 18% by weight, in particular 12.5 to 15% by weight. It is assumed that when injection molding is carried out with only one injection point for sealing, the non-polar tribological additive migrates to the interface of the polar polyketone with the mold wall during injection molding. Thus, in the seam region where the two flow fronts meet, there is a particularly high concentration of these additives, which leads to adhesion problems in commercial polyketones modified with 20% by weight PTFE and thus to subsequent seam breakage. The polyketone compounds according to the invention having less than 15 wt% of ultra-high molecular weight polyethylene do not show this problem due to the lower additive proportion.

Thus, in a preferred embodiment of the invention, the aliphatic polyketone according to the invention has a total proportion of tribological additives, i.e. of ultra-high molecular weight polyethylene and any further tribological additives that may be present, for example a total content of silicone oil, PTFE powder, graphite, molybdenum sulphide, boron nitride of less than 20% by weight, preferably less than 5% by weight, in particular less than 2.5% by weight. However, the above additives may be present, for example, in an amount of 0.1 to 19.5 wt%.

According to the invention, ultra-high molecular weight polyethylene, usually abbreviated to UHMWPE for ultra-high molecular weight polyethylene, refers to polyethylene having a molecular weight of more than 100, preferably 300 to 700, in particular 300 to 500, ten thousand g/mol, measured by means of an uge viscometer (dilute solution in decalin at 140 ℃). Due to this high molecular weight, ultra high molecular weight polyethylene is not meltable. This is advantageous compared to meltable plastics, such as LD-PE or HD-PE, because UHMWPE does not melt itself when compounded into an aliphatic polyketone melt, but continues to exist in the form of solid particles in the polymer matrix. The UHMWPE particles are non-polar and therefore incompatible with the polar aliphatic polyketone matrix and therefore aggregate at the interface. The polyketone compound thus has wear resistant particles on its surface, on the one hand reducing the frictional resistance and on the other hand reducing the material wear.

Unlike UHMWPE, LD-PE and HD-PE are meltable polyethylenes with melting ranges of about 110 ℃ and about 135 ℃, respectively, which completely melt when mixed into an aliphatic polyketone melt, distribute in the polymer matrix and form a blend (as described for example in DE 69513864T 2, WO 96/06889). The discrete PE particles are no longer present in the finished material blend and the advantages mentioned in the above section resulting from the solid UHMWPE particles are not achieved.

Furthermore, UHMWPE has significantly better wear resistance and impact strength than LD-PE and HD-PE due to its significantly higher molecular weight and associated higher intermolecular interactions.

Ultra-high molecular weight polyethylene can be obtained from monomeric ethylene by metallocene-catalyzed synthesis, wherein a polymer chain consisting of 100000 to 250000 monomer units is generally formed. Thus, according to the present invention, preference is given to ultrahigh molecular weight polyethylene having a polymer chain composed of from 100000 to 250000 monomer units.

Preferably, the average particle size of the ultra-high molecular weight polyethylene is in the range of from 10 μm to 300 μm, still more preferably from 20 μm to 50 μm, in particular 38 μm. In another preferred embodiment, the particles of ultra high molecular weight polyethylene are less than 75 μm. Thus, polyThe D50 value of ethylene is preferably below 75 μm and/or the D95 value is preferably below 75 μm. The specific gravity of the ultra-high molecular weight polyethylene is preferably 0.93 to 0.94g/cm³. The bulk density is preferably 0.3 to 0.6g/cm³More preferably 0.32 to 0.5g/cm³. The molecular weight is preferably 300 to 700 ten thousand g/mol, more preferably 300 to 500 ten thousand g/mol.

According to the present invention, aliphatic polyketones and ultra-high molecular weight polyethylene are the main components of the aliphatic polyketones according to the present invention. According to the invention, the proportion of aliphatic polyketone in the polyketone compound is from 85.0 to 99.5% by weight, preferably from 90.0 to 99.5% by weight, more preferably from 92.0 to 98.0% by weight, in particular from 92.5 to 95.0% by weight, based in each case on the total weight of the polyketone compound. Furthermore, according to the invention, the proportion of ultrahigh molecular weight polyethylene in the polyketone compound is from 0.5 to 15% by weight, preferably from 0.5 to 10% by weight, more preferably from 2.0 to 8.0% by weight, in particular from 5.0 to 7.5% by weight, based in each case on the total weight of the polyketone compound.

Detailed Description

In a preferred embodiment of the invention, the aliphatic polyketone has from 0.1 to 2.0% by weight, in particular from 0.5 to 1.5% by weight, of further tribological additives, for example silicone oils.

In a preferred embodiment of the invention, the melting point of the aliphatic polyketones is 210 to 230 ℃, in particular 220 to 222 ℃, measured according to DIN EN 11357-1. The glass transition point is from 5 ℃ to 20 ℃, preferably from 10 ℃ to 15 ℃, in particular from 11 ℃ to 13 ℃. The density of the aliphatic polyketone as measured according to ISO 1183 method is preferably 1.1 to 1.3g/cm³In particular 1.24g/cm³. The aliphatic polyketones have a moisture absorption of from 0.3 to 1.2%, in particular from 0.8 to 0.9%, at 70 ℃ and 62% relative humidity, measured according to the method of ISO 1110. The MVR, measured according to the method of ISO1133, is preferably between 2 and 80cm at 240 ℃ and a test weight of 2.16kg³In the range of/10 min, in particular from 6 to 60cm³In the range of/10 min.

In a preferred embodiment of the invention, the aliphatic polyketone is a terpolymer, preferably prepared from ethylene, carbon monoxide and an olefin having from 3 to 5 carbon atoms (preferably propylene and/or butene, especially propylene). The carbon monoxide and the olefin are preferably arranged in a strictly alternating fashion in the polymer chain.

In a preferred embodiment of the invention, the aliphatic polyketone has an average molecular weight Mn (number average molecular weight) of between 60000 and 100000 and/or an Mw (weight average molecular weight) of between 132000 and 320000, the polydispersity index preferably being between 2.2 and 3.2.

The polyketides according to the invention may comprise silicone oils and other liquid or solid lubricants. In addition, other common polymeric additives, such as age resistors, fillers, flame retardants and pigments, as well as other polymeric materials, may be included to improve or otherwise alter the properties of the composition. The content of the liquid lubricant, for example, silicone oil is preferably 0.0 to 2.0% by weight, particularly preferably 0.0 to 1.5% by weight, in particular 0.0 to 1.0% by weight.

In a preferred embodiment of the invention, the aliphatic polyketide has a coefficient of friction of from 0.1 to 0.4, more preferably from 0.1 to 0.3, in particular from 0.1 to 0.25, measured on a lewis test rig at a speed v of 0.84m/s, a pressure p of 0.84MPa and under no lubrication. Furthermore, in a preferred embodiment of the invention, the aliphatic polyketone compound has an average wear coefficient of 1 x 10 measured on a lewis test bench at a speed v of 0.84m/s, a pressure p of 0.84MPa and under no lubrication conditions^-7To 1 x 10^-4mm³Nm, more preferably 1 x 10^-7To 1 x 10^-5mm³/Nm。

Furthermore, the aliphatic polyketides according to the invention preferably have a tensile modulus of elasticity of 1600 to 1850MPa, measured according to DIN EN ISO527-2/1A/50, a tensile strength of 55 to 65MPa, measured according to DIN EN ISO527-2/1A/50, and/or an elongation at break of 20 to 40%, measured according to DIN EN ISO 527-2/1A/50.

Furthermore, in the tribological test described in example 2, the aliphatic polyketone compounds according to the invention preferably have a coefficient of friction of μ -0.38 to 0.42 throughout the test, a coefficient of friction of μ -0.38 to 0.40 at "steady state", and a coefficient of friction of μ -0.38 to 0.40 throughout the testLoss coefficient of 10 x 10^-6To 20 x 10^-6And/or a wear coefficient of 2 x 10 at "steady state^-6To 5 x 10^-6。

The present invention also provides a process for preparing an aliphatic polyketone compound comprising blending 99.5 to 85.0 wt% of an aliphatic polyketone with 0.5 to 15 wt% of an ultra-high molecular weight polyethylene, more preferably 98.0 to 92.0 wt% of an aliphatic polyketone with 2.0 to 8.0 wt% of an ultra-high molecular weight polyethylene, more preferably 95.0 to 92.5 wt% of an aliphatic polyketone with 5.0 to 7.5 wt% of an ultra-high molecular weight polyethylene. Here, the weight data are based on the total weight of the aliphatic polyketone compounds.

The components of the aliphatic polyketide are preferably mixed using extrusion techniques. Preferably, a co-rotating twin-screw extruder is used, but a counter-rotating twin-screw extruder, a planetary roll extruder and a co-kneader may also be used as the extruder. Single screw extruders are more suitable for conveying and not for compounding and are therefore less suitable for preparing the aliphatic polyketones of the present invention. In one embodiment, the aliphatic polyketone is predried at 70 ℃ to 90 ℃ for 4 hours and then metered into the twin-screw extruder by means of a metering device, preferably a gravimetric metering device. The temperature of the feed zone is preferably in the range of 50 ℃ to 100 ℃ and the temperature of the extruder zone is preferably in the range of 225 ℃ to 254 ℃. The ultra-high molecular weight polyethylene is preferably fed into the polymer melt by means of a further metering device, preferably a gravimetric metering device. After leaving the extruder nozzle, the strip is preferably placed on a conveyor belt and cooled by water and/or air before being comminuted in a downstream granulator. Advantageously, the prepared granules are dried to remove moisture introduced by the cooling process.

According to the invention, the aliphatic polyketone and the ultra-high molecular weight polyethylene are mixed with each other and with any other components present in quantitative proportions such that they form the main constituent of the aliphatic polyketone compound. Preferably, the polyketone is added to the compound in an amount of 99.5 to 90.0 wt.%, more preferably 98.0 to 92.0 wt.%, in particular 95.0 to 92.5 wt.%. Further, the ultra-high molecular weight polyethylene is preferably added to the compound in an amount of 0.5 to 10.0 wt%, more preferably 2.0 to 8.0 wt%, more preferably 5.0 to 7.5 wt%. An amount of ultra-high molecular weight polyethylene of less than 10% by weight is advantageous, since this makes it particularly easy to prevent clogging of the extruder nozzle.

Ultra high molecular weight polyethylene tends to agglomerate, accumulate in the extruder nozzle area and clog. However, it is also possible to use the above-described process for the preparation of compounds having more than 10% by weight of ultra-high molecular weight polyethylene, in particular in small batches, but it is advantageous to take special technical measures for the continuous preparation due to agglomeration of the UHMWPE and the clogging of the extruder nozzles associated therewith.

The aliphatic polyketides of the present invention can be processed by conventional forming methods (e.g., extrusion, compression molding, and injection molding) into a variety of products that are particularly suitable for applications requiring good tribological properties.

The invention also provides shaped bodies, preferably rotationally symmetrical shaped bodies, comprising the polyketides according to the invention, in particular seals (e.g. rod and/or piston seals), structural parts (with and/or without sealing function), scraper elements, coupling elements, support rings (anti-extrusion rings), wear strips and/or guides.

In a preferred embodiment, the shaped bodies exhibit a joint strength of more than 120N in the bending test as described in example 2. Furthermore, as described in example 2, the shaped bodies preferably do not break at the seams in a bending test of the maximum transverse path (43.31 mm).

The aliphatic polyketones according to the invention are particularly suitable for use in shaped bodies produced by injection moulding processes, in particular by injection moulding processes using only one injection point, for example a point or tunnel gate.

The invention also relates to the use of the aliphatic polyketides according to the invention for producing shaped bodies, preferably rotationally symmetrical shaped bodies, in particular seals (for example rod and/or piston seals), structural parts (with and/or without sealing function), scraper elements, coupling elements, gears, plain bearings, support rings, in particular anti-extrusion rings, wear strips and/or guides.

The invention is illustrated in more detail below by means of examples.

Example 1: preparation of polyketides of the invention

The tribologically modified polyketone compounds of the invention were extruded on a ZSE 27iMAXX model 27mm twin-screw extruder from Leistritz Corp (screw diameter: 28.3mm, channel depth: 5.6mm (without gap), D_a/D_i1.66, maximum torque: 256Nm, screw rotation speed: 600-.

The aliphatic polyketone is AKRO-PLASTIC GmbHPK-VM natur(4774)。PK-VM natur (4774) is a non-reinforced polyketone type with high flow. Its melting point, measured according to DIN EN11357-1, is 220 ℃ and its density, measured according to ISO 1183, is 1.24g/cm³A hygroscopicity, measured according to ISO 1110, of between 0.8 and 0.9% at 70 ℃ and 62% relative humidity and an MVR, measured according to ISO1133, of 60cm³/10min。

The ultra-high molecular weight polyethylene used is INHANCE UH-1700 from Nordmann Rassmann. The average particle size of the UHMWPE particles is 38 μm and all particles are smaller than 75 μm. INHANCE UH-1700 is a surface treated particle of UHMWPE type, which gives it better dispersion and better adhesion in the surrounding polymer. The specific gravity of the material is 0.93 to 0.94g/cm³Bulk density of 0.32 to 0.5g/cm³The molecular weight is 300 to 500 ten thousand g/mol.

Aliphatic polyketones were fed to the feed zone of the extruder with a BASIC401 solid feeder. The temperature of the feed zone was set at 50 ℃. The temperature of the 12 heating zones of the extruder was set in the range of 230 ℃ to 245 ℃. The temperature of the nozzle was 230 ℃. The melting temperature of the polymer was determined to be 238 ℃. The total throughput of the material was 19.97 kg/h.The throughput of PK-VM is 18.97kg/h, and the throughput of Inhance UH-1700 is 1.0 kg/h. The finished compound was discharged through a single orifice nozzle onto a conveyor belt, cooled with spray water and fed to a pelletizer. The granules were dried at 80 ℃ for 30 to 45 minutes, since they still contained a large amount of adhering residual moisture upon cooling with water.

The pellets were dried again at 80 ℃ for 4 hours before injecting the compound into the sample.

Example 2: mechanical and tribological testing of the polyketides in example 1

Mechanical and tribological test specimens in Arburg GmbH&Kg on a 320C 600-. AIM available from Axxicon Moulds was used^TMAnd the quick replacement mold is used as an injection mold. S1A draw bars for mechanical testing and Lewis samples for tribological testing were prepared.

Mechanical tests have shown that the tensile modulus of elasticity of the compounds measured in accordance with DIN EN ISO527-2/1A/50 is 1725. + -. 10MPa, the tensile strength measured in accordance with DIN EN ISO527-2/1A/50 is 58.7. + -. 0.2MPa and the elongation at break measured in accordance with DIN EN ISO527-2/1A/50 is 28.2. + -. 7.1%.

Tribological tests were carried out on a Lewis test bench of type LRI-1a from Lewis Research Inc. D2 steel/52100 with a chemical composition of 100Cr6 was used as the mating surface. The test was carried out in the unlubricated state. The speed v was 0.84m/s and the contact pressure p was 0.84 MPa. These two parameters are chosen so that the temperature in the continuous operating regime is between 54 ℃ and 58 ℃. Under these test conditions, the coefficient of friction of this compound was 0.275 μ over the entire test period, 0.269 μ during "steady state", and the wear profile over the entire test periodNumber 6.556 x 10^-6The wear coefficient during "steady state" was 1.862 x 10^-6. Measuring the modification of PTFE compared with the Compounds according to the inventionPK-VM TM and unmodifiedPK-VM. Unmodified under similar experimental conditionsThe coefficient of friction of PK-VM was 0.412 throughout the experiment, 0.390 during "steady state", and 15.641 x 10 during the entire experiment^-6The wear coefficient during "steady state" was 3.814 x 10^-6. Modified tribologically under similar experimental conditionsPK-VM TM showed a coefficient of friction μ -0.221 throughout the experiment, a coefficient of friction μ -0.214 during "steady state", and a wear coefficient of 2.087 x 10 throughout the experiment^-6The wear coefficient during "steady state" was 1.670 by 10^-6. The results show that the PTFE modified benchmarkPK-VM TM-although it contains significantly more tribological additives (about 20 wt% PTFE) than the compound according to the invention (5 wt% tribological additives) -performed only slightly better.

To evaluate the seam strength, five rod seals according to the geometry shown in fig. 1 (1: rod diameter 50mm) were produced in an injection molding process with only one injection point from the compound produced in example 1, and then subjected to a bending test. The seals were each arranged in the experimental setup such that the seam and the opposite injection point were horizontally aligned and a pressure fin (punch diameter: 25mm) pressed against the seals at an angle of 90 ° with respect to the seam and the injection point. A single support point is used. A pre-pressure of 5N was applied to the pressure fins and then moved at a speed of 5 mm/min. The maximum crossing distance was 43.3 cm. In this experimental setup, the tribologically modified polyketone compound prepared in example 1 did not show any breaks at the seams. In all five rod seals tested, the pressure fin was moved to the maximum crossover distance without any seal rupture (see table 1).

Table 1: results of bending tests of rod seals prepared from the polyketones of the invention described in example 1.

Rod seals made from a commercially available polyketone friction modified with about 20 wt% PTFE were tested under similar experimental conditions as compared to a polyketone according to the invention. Of the four rod seals tested, three failed after a crossover distance of 32.3 to 35.4mm and a compressive force of 96.7 to 105.4N (see table 2).

Table 2: commercial polyketides modified with about 20% by weightBending test results for PK-VM TM prepared rod seals.

Furthermore, rod seals made of the compound according to the invention were tested on a hydraulic test bench under application-relevant conditions, against the current reference, several times with rod seals made of PTFE/bronze compounds. The test stand is schematically shown in fig. 2. The test bench consists of the following components: extrusion clearance (1), experimental sealing member (2), guide (3), pressure chamber (4). The rod (5) moves horizontally. The test bench was set up as follows:

the leakage and extrusion stability in continuous use were evaluated. It is shown here that the PTFE/bronze compound is damaged by gap squeezing after approximately 40,000 strokes and then the leakage increases from 20 drops to 90 drops after 50,000 strokes until the end of the running time, increasing more than four times. Seals made from polyketones according to the invention, prepared as described in example 1, were crush-stable over the entire running time of 50,000 strokes (until the end of approximately 20 drops of leakage).