HK1114360B - Composite body made from polyacetal and thermoplastic vulcanised elastomer - Google Patents

Description

Composite body composed of polyacetal and thermoplastic vulcanized rubber elastomer

Technical Field

The present invention relates to a composite body consisting of a polyacetal and at least one thermoplastic vulcanizate (TPV) elastomer (═ TPV), and to a process for its preparation, in which the TPV elastomer is modified by using a non-olefinic thermoplastic material so that adhesive or cohesive bonding can be obtained between the polyacetal and the TPV. Degradation of the polyacetal can be avoided by the use of specific crosslinker systems.

Background

The engineering material polyacetal, i.e. Polyoxymethylene (POM), has excellent mechanical properties and is furthermore generally resistant to all common solvents and motor fuels. Molded parts composed of polyacetal are very frequently used in snap-fastener (Schnapp) connections, in particular clips, in every field of daily life, because of the good strength and hardness associated with the excellent resilience. The excellent sliding friction property is the reason why POM is used for many movable parts such as transmission parts, deflection rollers, gears, or shift levers. Moldings composed of POM are also very frequently used in automobile construction. Due to the very good mechanical stability and chemical resistance, a wide variety of housings and keyboards made of POM are also produced.

However, POMs have a low mechanical damping factor at room temperature, which in some application cases necessitates the use of soft damping components. Sealing at the connection points is also often required when installing moldings made of POM. The high surface hardness of moldings made of POM and the low coefficient of sliding friction of POM can lead to slippage of articles stacked on top and limit the operational safety of switching and operating components made of POM, for example. On the other hand, it is also more common to use a combination of hard and soft materials in order to combine the specific properties of these materials with each other. The hard material is intended to result in the strength of the component, and the soft material, because of its elastic properties, assumes the function of sealing or vibration damping and sound damping, or in a change in the surface feel. Proper adhesion between hard and soft components is important in these applications.

The gasket and damping assembly have hitherto been provided separately and usually in a further operating step they are mechanically fixed or adhesively bonded, which entails additional work and sometimes considerable additional costs.

A more recent and cost effective process is multi-component injection molding. In this method, for example, the second component is injection molded onto the previously molded first component. The adhesion that can be achieved between the two components is of great importance for this process. Although in multi-component injection molding this adhesion can often be further improved in interlocking (formschlussig) connections by means of an undercut fit. However, good basic adhesion between selected components by chemical affinity is often a prerequisite for their use.

Combinations of polypropylene and polyolefin elastomers or styrene-olefin elastomers, polybutylene terephthalate and polyester elastomers or styrene-olefin elastomers, for example, prepared by multicomponent injection molding, are well known. Polyamides also exhibit adhesion to a very large number of soft components.

Molded parts composed of polyacetal and having functional components directly molded thereon are also known, and are produced using uncrosslinked rubbers (DE-C4439766). However, the adhesive strength of such composites has not been satisfactory.

Further publications relate to composites of this type which consist in particular of polyacetals, rubber copolymers, reinforcing fillers, crosslinking agents and, if appropriate, further conventional additives (DE-A19641904). Here, the rubber component prepared in the absence of any crosslinking agent is first of all joined, after addition of the crosslinking agent, by injection molding with a polyacetal molding which has been added beforehand at 130-170 ℃ to form a polyacetal-rubber complex by vulcanization of the rubber copolymer in a further step at 140-180 ℃. Particularly good adhesion of the polymer components is not achieved until vulcanization by the rubber fraction. However, this additional step was evaluated as disadvantageous due to the elevated vulcanization temperature and time.

DE-C-19845235 discloses composites composed of polyacetals and styrene-olefin elastomers which have been modified by the addition of non-olefinic thermoplastics. Disadvantages are, however, their relatively high values for the compression set in the various application temperature ranges and their unsatisfactory chemical resistance to aromatic and aliphatic hydrocarbons, fats and oils. However, there is a need for hard/soft components for automotive engine compartments, which can be produced, for example, by multi-component injection molding techniques, which, in addition to providing lower values of the compression set in various application temperature ranges, also provide higher temperature stability (lower creep behavior) in combination with improved chemical resistance.

Another alternative possibility in the production of the composite is provided by the use of an adhesive intermediate layer. For example, EP 0921153 a1 discloses that polar and non-polar polymers can be mixed by using a specific block polymer consisting of a functionalized polymer and a polyamide as a compatibilizer. The polymer mixture obtained can be used as an adhesive interlayer for the production of composites consisting of polar and non-polar thermoplastic polymers. According to EP 0837097 a1, the preparation of composites composed of polar and nonpolar thermoplastic polymers is also successfully achieved with the aid of block copolymers comprising chemically modified polyolefins and thermoplastic polyurethanes, copolyesters or polyamides. However, it is desirable to dispense with the use of complex block copolymers in the preparation of composites composed of polyacetal (polyayene) and thermoplastic elastomers.

Disclosure of Invention

It is therefore an object of the present invention to provide a composite body composed of polyacetal and a thermoplastic elastomer, in which the disadvantages and limitations mentioned are absent.

Experience to date in the search for new hard/soft junctions has shown that direct combination of polyacetal and TPV is not possible (Advanced Elastomer Systems, rev.06/2001, page 1;thermoplastic polymersRubber 8211-55B 100TPV) due to the degradation of polyacetal caused by the crosslinking agents commonly used in TPV, such as phenolic resins or peroxides.

It has now surprisingly been found that adhesive bonds having the desired properties with very good adhesion can be achieved from polyacetals and TPVs modified with non-olefinic thermoplastics. In contrast, with TPV modified with olefinic thermoplastic, no adhesion to polyacetal is exhibited.

The invention accordingly provides a composite body composed of at least one polyacetal and at least one modified TPV elastomer, comprising from 10 to 70% by weight of a non-olefinic thermoplastic material, based on the weight of the modified TPV elastomer, and from 1 to 30% of a compatibilizer, and also a process for preparing such a composite body, wherein a molding composed of polyacetal is first molded and then a coating or at least one molding composed of the modified TPV elastomer is injection-molded onto it, or the modified TPV elastomer is first pre-injection-molded and then a coating or at least one molding composed of polyacetal is applied onto it by injection molding, wherein the polyacetal is bonded to the modified TPV elastomer by adhesive or cohesive means. The composite of the present invention has a peel resistance of at least 0.5N/mm. According to the invention, the modified TPV elastomer should have a preferred value of compression set after 24h at 70 ℃ of < 65% according to DIN ISO 815.

The composite bodies according to the invention are formed here by polyacetal moldings which have been coated partly or completely with the modified TPV elastomer or onto which one or more moldings composed of the modified TPV elastomer, also referred to as functional parts, have been molded directly. This may be, for example, a planar polyacetal molding with a layer consisting of a TPV elastomer on one side. Examples of these are skid pads, grip grooves, operating and switching assemblies, functional parts with seals or damping assemblies, and inner and outer claddings on two-wheeled vehicles, on motor vehicles, on aircraft, on rail vehicles and on ships, which achieve the required shape stability due to polyacetal and the required friction properties, sealing function, feel or appearance due to the elastomer layer.

However, the composite body may also consist of one or more polyacetal moldings of any desired shape onto which one or more moldings of any desired shape consisting of the modified TPV elastomer have been directly molded. The expression "direct molding" is intended for the purposes of the present invention to mean the direct injection molding of a functional component, in particular in a multicomponent injection molding process, onto a molding composed of polyacetal, with which the functional component is intended to form a cohesive, strong joint.

By using TPV elastomers modified with non-olefinic thermoplastics, it is possible, for example, to mold sealing or damping components composed of elastomers directly onto moldings composed of polyacetal without further assembly steps. Considerable cost savings can be achieved in the production of the composite body according to the invention by the omission of the processing steps required up to now for the assembly of the functional components.

The composite body is prepared by well-known methods and processes. The use of a multicomponent injection molding process is advantageous, in which the polyacetal is first molded in an injection mold, i.e.pre-injection molded, and the coating or molding consisting of the modified TPV elastomer is then injection molded onto the polyacetal molding.

If the geometry of the moldings permits, the composite bodies can also be produced in reverse order by a multicomponent process, i.e.first of all by preliminary injection molding of the molding composed of TPV elastomer and then injection molding a coating composed of polyacetal thereon or applying at least one molding composed of polyacetal thereto by injection molding.

Here, the temperature of the materials during the preparation of the polyacetal moldings is in the usual range, i.e.in the range from about 180 ℃ to 240 ℃ and preferably from 190 ℃ to 230 ℃ for the polyacetals described below. The mould itself is tempered to a temperature in the range of 20-140 c. The mold temperature at the upper end of the temperature range is advantageous for the shape accuracy and dimensional stability of a hard member body composed of polyacetal, a partially crystalline material.

Once the cavity in the mold is completely filled and the holding pressure is no longer effective (sealing point), the polyacetal molded part can be finally completely cooled and demolded into the first part of the composite body (premold). In a second, subsequent separate injection molding step, this pre-molded part is then inserted or transferred, for example, into a further mold with a cavity left behind, and the material with the lower hardness, i.e. the modified TPV elastomer, is injected into the mold and is injection molded there onto the polyacetal molded part. This process is called an insertion process or a transfer process. It is particularly advantageous for the adhesion to be subsequently achieved that the pre-injection-molded polyacetal moldings are preheated to a temperature in the range from 80 ℃ to a temperature close to below the melting point. Thus, the TPV elastomer applied by injection molding and its penetration into the interfacial layer facilitate the initial melting of the surface.

However, it is also possible to only partially demold the pre-injection molded polyacetal parts and to move them together with a part of the initial mold (e.g. the casting plate, the pusher side, or only one indicator plate) into another, larger cavity.

Another possible method consists in injecting the modified TPV elastomer into the same mould without intermediate opening of the machine and further transport of the pre-moulded part consisting of polyacetal. Here, the mold cavity intended for the elastomer component is first sealed by a slidable insert or core during injection of the polyacetal component and is not opened until the elastomer component is injected (sliding technique). This process variant is also particularly advantageous for achieving good adhesion, since the melt of the TPV elastomer already appears on the still hot pre-molding after a short cooling time.

If appropriate, it is possible to apply further mouldings composed of polyacetal and of the modified TPV elastomer by injection moulding in a multicomponent injection moulding process, either simultaneously or in successive subsequent steps.

When applying the modified TPV elastomer by injection molding, it is advantageous for good adhesion to select a set value as high as possible for the mass temperature and the injection pressure and holding pressure. The material temperature of the TPV elastomer is generally in the range from 170 ℃ to 270 ℃ and is limited upwards by its decomposition. The injection rate and the values of the injection pressure and holding pressure depend on the machine and the moulding and are to be adapted to the particular circumstances.

In all process variants, the mold is tempered in a second step to a temperature in the range from 20 ℃ to 140 ℃ with or without demolding of the premolded piece. Depending on the part configuration, the mold temperature can be judiciously reduced to some extent to thereby optimize demoldability and cycle time. Once the part is cooled, the composite is demolded. It is important for the mold construction here that the pusher is mounted in a suitable location in order to minimize the load of the material joint seam. Sufficient venting of the cavity in the seam region is also provided in the mold construction to keep the bond inhibition between the two components, which is caused by the entrapped air, as low as possible. The nature of the mold wall roughness exerts a similar effect. For the formation of a good bond, a smooth surface at the location of the joint seam is advantageous, since then less air is entrapped in the surface.

The polyacetals used according to the invention are selected from the known Polyoxymethylenes (POM), which are described, for example, in DE-A2947490. It is the preparation of the above-described composites using these polyoxymethylenes that has not been successful to date. Polyoxymethylene generally means unbranched linear polymers which generally contain at least 80 mol%, preferably at least 90 mol%, of formaldehyde units (-CH)₂O-). The term "polyoxymethylene" here encompasses not only homopolymers of formaldehyde or its cyclic oligomers, such as trioxane or tetraoxane, but also the corresponding copolymers.

Homopolymers of formaldehyde or trioxane are polymers whose hydroxyl end groups are chemically stabilized against degradation in a known manner, for example by esterification or etherification.

Copolymers are polymers composed of formaldehyde or its cyclic oligomers, in particular trioxane, and cyclic ethers, cyclic acetals, and/or linear polyacetals.

Comonomers which may be used are, on the one hand, cyclic ethers having 3, 4 or 5, but preferably 3, ring members, and, on the other hand, cyclic acetals other than trioxane having 5 to 11, preferably 5, 6, 7 and 8, ring members, and also linear polyacetals, in each case used in amounts of 0.1 to 20 mol%, preferably 0.5 to 10 mol%.

The melt index (MFR value 190/2.16) of the polyacetal polymers used is generally from 0.5 to 75g/10min (ISO 1133).

Modified types of POM may also be used. Included among these modification types are, for example, blends formed from POM with: TPE-U (thermoplastic polyurethane elastomer), MBS (methyl methacrylate-butadiene-styrene-core-shell elastomer), methyl methacrylate-acrylate-core-shell elastomer, PC (polycarbonate), SAN (styrene-acrylonitrile copolymer), or ASA (acrylate-styrene-acrylonitrile copolymer compound).

Modified TPV elastomer used according to the invention means a compound having a hardness of from 30 to 90 Shore A (determined according to DIN 53505, corresponding to ISO 868) comprising the following components:

a) 2-75 wt.%, preferably 5-75 wt.%, particularly preferably 20-50 wt.% of a fully or partially crosslinked ethylene-propylene-diene rubber (EPDM) in 1-50 wt.%, preferably 3-50 wt.%, particularly preferably 10-30 wt.% of a polyolefin matrix, for example consisting of an optionally functionalized Polyethylene (PE) or an optionally functionalized polypropylene (PP) and/or copolymers of these, preferably polypropylene, with the addition of 0.05-10 wt.%, preferably 0.1-5 wt.% of a stabilizer, preferably a phenolic antioxidant and/or crosslinking coagent, preferably an azo compound, maleimide, selenium, tellurium, sulfur, a sulfur-containing compound, particularly a thio compound, and particularly preferably a peroxide, particularly an alkyl or aryl peroxide, such as dicumyl peroxide, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane or di-t-butyl peroxide. Component a) may also comprise further additives, in particular plasticizers and fillers, if appropriate.

b)1-30 wt% of at least one compatibilizer, such as optionally functionalized styrene-olefin block copolymers, methacrylate-butadiene-styrene (MBS), MABS (methyl methacrylate-acrylonitrile-butadiene-styrene), functionalized EPDM, or ethylene-propylene rubber (EPM) and/or functionalized polyolefin; and

c)10-70 wt% of a non-olefinic thermoplastic material.

The TPV elastomer may additionally comprise

d) If appropriate up to 50% by weight of plasticizer oil (e.g. paraffinic mineral oil, synthetic oil, ester plasticizer, naphthenic oil, semisynthetic oil, silicone oil, etc., preferably paraffinic mineral oil), and/or up to 50% by weight of organic and/or inorganic fillers or reinforcing materials (e.g. chalk, talc, glass beads, glass fibres, silicic acid(s) ((R))) Nanoparticles, such as phyllosilicates and the like, kaolin, wollastonite, bentonite, magnesium hydroxide and/or aluminum hydroxide and the like, preferably chalk); and/or

e) With the additives usually used in amounts, such as antioxidants, light stabilizers, nucleating agents, mold release aids, internal or external lubricants, pigments, carbon black, halogen-free and/or halogen-containing flame retardants, optical brighteners, hydrocarbon resins and/or epoxy resins, antistatics, biocides, fungicides and the like, customary crosslinking agents, such as peroxides, phenolic resins, and sulfur or the like, preferably peroxides, and customary crosslinking enhancers, such as silanes, guanidines, sulfur-containing compounds, such as cadmium-, copper-, lead-, zinc-and tellurium-selenium-containing compounds, in particular dithiocarbamates, -thiurams or xanthates, thioureas, triallyl isocyanurates, triallyl cyanurates, trimethylolpropane trimethacrylates, alpha-methylstyrene or the like.

The wt% data given are based on the total weight of the TPV elastomer (compound).

The polyolefins and copolymers mentioned in sections a) and b) are, if appropriate, functionalized by groups or compounds which may be selected from: carbonyl-and/or carboxyl-containing compounds, such as maleic acid, its derivatives, such as maleimide and/or Maleic Anhydride (MAH), acrylic acid, acrylates and/or their derivatives, in particular GMA (glycidyl methacrylate), compounds containing epoxy groups, such as glycidyl methacrylate or glycidyl ethacrylate, amino or imino groups, amide groups, metal carboxylate groups, carbonate groups, nitrile groups, ether groups, ester groups, carbamate groups, cyanate groups, isocyanate groups, cyanurate groups, isocyanurate groups, and/or hydroxyl groups. Functionalized polyolefins also mean mixtures with other polar materials, such as PP/ABS blends, PP/PA blends or PE/PMMA blends (where ABS ═ acrylonitrile-butadiene-styrene copolymer and PMMA ═ polymethyl methacrylate).

For the EPDM rubbers mentioned in section a), it is in principle possible to use any desired diene. The diene monomers mainly used are cis, cis-1, 5-cyclooctadiene, exo-dicyclopentadiene, endo-dicyclopentadiene, 1, 4-hexadiene and 5-ethylidene-2-norbornene. 5-ethylidene-2-norbornene is preferred.

The component a) used preferably comprises crosslinked, in particular peroxide-crosslinked EPDM/polyolefins, wherein component a) itself preferably contains no more residues of unreacted crosslinking agent or at least virtually no crosslinking agent, wherein this means a residual crosslinking agent content of less than 0.1 wt.%, preferably less than 0.5 wt.%, particularly preferably less than 0.01 wt.%. This can be achieved, for example, by: the crosslinking agent is consumed or degraded during compounding of the TPV elastomer. For this purpose, small amounts of crosslinking agents of from 0.01 to 5% by weight, particularly preferably from 0.1 to 2% by weight, based on the weight of the TPV elastomer, are preferably used.

The non-olefinic thermoplastic materials mentioned under c) are selected from thermoplastic polyester urethane elastomers, thermoplastic polyether urethane elastomers, thermoplastic polyesters (e.g. polyethylene terephthalate and/or polybutylene terephthalate), thermoplastic polyester ester elastomers, thermoplastic polyether amide elastomers, thermoplastic polyamides, thermoplastic polycarbonates, thermoplastic polyacrylates, acrylate rubbers, styrene-acrylonitrile-acrylate rubbers (ASA). Mixtures of the mentioned materials may also be used.

Component a) is also used in the form of a TPV masterbatch, which is generally referred to as a dynamically crosslinked pre-mix comprising, based on the TPV masterbatch (pre-mix):

10 to 75 wt.%, preferably 20 to 40 wt.%, of an ethylene-propylene-diene rubber (EPDM),

5-50 wt.%, preferably 5-20 wt.% of a polyolefin, Preferably Polypropylene (PP),

from 0 to 70% by weight, preferably from 35 to 60% by weight, of a plasticizer oil, in particular a paraffinic mineral oil,

from 0 to 50% by weight of an organic and/or inorganic filler, preferably chalk or barium sulphate,

0.1 to 10 wt.%, preferably 0.2 to 5 wt.% of a stabilizer, preferably a phenolic antioxidant, and/or a crosslinking coagent, preferably a peroxide.

The proportion by weight of the TPV masterbatch (component a) incorporated into the TPV elastomer is preferably from 20 to 89% by weight, particularly preferably from 30 to 70% by weight, based on the total weight of the TPV elastomer.

Examples TPV master batches consisting of peroxide crosslinked EPDM/PP compounds were used.

Suitable plasticizer oils, inorganic fillers, stabilizers, and crosslinking aids for the TPV masterbatch are those mentioned above.

The compounds were prepared by means of a co-rotating twin-screw kneader (ZSK) by means of the usual compounding processes.

Modified TPV elastomers having different properties can be prepared by the constitution of the TPV masterbatch, and the variation of the proportions of components a) to e).

The modified TPV compound of the invention has a hardness of from 30 to 90 Shore A, preferably from 40 to 80 Shore A. This hardness can be adjusted by the ratio of plasticizer and thermoplastic components, as desired.

For the thermoplastic fraction in the TPV elastomer, olefinic thermoplastics such as polyethylene, polypropylene and polyolefin elastomers, optionally also talc-reinforced or filled with glass fibers, can generally be used. However, as shown by tests with TPV elastomers of this type modified with olefinic thermoplastics (see comparative test PTS-uni prene-7100-55 x 9000), this TPV elastomer compound does not have adhesion to polyacetals.

Thus, according to the invention, the TPV elastomer is modified by compounding with a non-olefinic thermoplastic.

Not only polyacetals but also modified TPV elastomer compounds may generally contain the above-mentioned conventional additives, such as stabilizers, nucleating agents, mold release agents, lubricants, fillers, and reinforcing materials, pigments, carbon black, light stabilizers, flame retardants, antistatic agents, plasticizers, or optical brighteners. The additives are present in amounts generally used.

The composite body according to the invention can be used, in addition to the fields of application in the automotive engine compartment mentioned in the introduction, as a connecting element in the form of a fitting, coupling, roller, bearing, and as a functional part with integrated sealing and/or damping properties, as well as an anti-slip and easy-to-grip element. These also include housings in the construction of automobiles, such as door locking housings, window lift housings, or sliding roof sealing elements and the like, in addition to fastening elements with integrated seals, such as clips with sealing rings or with sealing discs, trim molding with integrated sealing lips, sealing elements for compensation of expansion joints, fastening elements with good damping properties, such as clips with vibration or noise damping cores, transmission components, such as gears with damping elements, gear transmissions with integrated flexible couplings, anti-slip and easy-to-grip elements, such as control levers or control buttons, or gripping surfaces on electrical equipment or writing pens, and links with elastic surfaces.

Detailed Description

Examples

The exemplified THERMOPRENE designations (modified TPV), UNIPRENE, and THERMOFLEX (comparative) refer to commercial products available from PTS-Plastic technology service GmbH (Adelshofen, Germany). The HOSTAFORM designation (polyacetal) listed is a commercial product from Ticona GmbH (Kelsterbach, Germany).

Polyacetal to be used

C 9021

Polyoxymethylene copolymer consisting of trioxane and about 2 weight percent ethylene oxide.

Melt index MFR 190/2.16(ISO 1133): 9g/10min

Modification: is free of

S9064

Polyoxymethylene copolymer consisting of trioxane and about 2 weight percent ethylene oxide.

Melt index MFR 190/2.16(ISO 1133): 9g/10min

Modification: 20% by weight of a partially aromatic polyester TPE-U

S9244

Polyoxymethylene copolymer consisting of trioxane and about 2w t% ethylene oxide.

Melt index MFR 190/2.16(ISO 1133): 9g/10min

Modification: 25 wt% MBS core-shell modifier

Modified TPV elastomer used

PTS-THERMOPRENE-85A10^*9007: hardness 85 Shore A, density 1.09/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP) (see above for preparation), thermoplastic polyetherester elastomer (TPE-E) at a content of 40%, hardness 40 Shore D, commercially available products such as those marked ARNITEL (DSM) or HYTREL (Du PONT), 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 15% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-75A10^*9007: hardness 75 Shore A, density 1.08g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyetherester elastomer at a content of 40%, hardness 25 Shore D, commercially available products such as those marked ARNITEL (DSM) or HYTREL (Du PONT), 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 15% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-70A10^*9000: hardness 70 Shore A, density 1.05g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyetherester elastomer at 35% level, hardness 25 Shore D, such as the commercial products labeled ARNITEL (DSM) or HYTREL (Du PONT), about 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 3% partially functionalized HSBC (hydrogenated styrene-olefin block copolymer), 5% plasticizer oil, 10% inorganic filler (CaCO)₃) And addingAnd (3) preparing.

PTS-THERMOPRENE-60A10^*9000: hardness 60 Shore A, density 1.04g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyetherester elastomer at 25% level, hardness 25 Shore D, such as the commercial products labeled ARNITEL (DSM) or HYTREL (Du PONT), 5% MBS (methacrylate-butadiene-styrene) core-shell modifier, 10% partially functionalized HSBC (hydrogenated styrene-olefin block copolymer), 20% plasticizer oil, 10% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-55A10^*9000: hardness 55 Shore A, density 1.05g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyetherester elastomer at 25% level, hardness 25 Shore D, such as the commercial products labeled ARNITEL (DSM) or HYTREL (Du PONT), about 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 10% partially functionalized HSBC (hydrogenated styrene-olefin block copolymer), 20% plasticizer oil, 10% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-40A10^*9007: hardness 40 Shore A, density 1.00g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyetherester elastomer at 20% level, hardness 25 Shore D, such as the commercial products marked ARNITEL (DSM) or HYTREL (Du PONT), 15% partially functionalized HSBC (hydrogenated styrene-olefin block copolymer), 30% plasticizer oil, 10% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-75A66^*800: hardness 75 Shore A, density 1.14g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), polyamide 6 at a content of 10%, HSBC partially functionalized at 15% (hydrogenated)Styrene-olefin block copolymer), 25% of inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-65A22^*807: hardness 63 Shore A, density 1.05g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), 40% content of Thermoplastic Polyester Urethane (TPU), hardness 85 Shore A, commercially available products such as those named DESMOPAN (Bayer AG) or ELASTOLLAN (Elastogran AG), 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 10% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-75A20^*9000: hardness 73 Shore A, density 1.08g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), 40% content of Thermoplastic Polyether Urethane (TPU), hardness 85 Shore A, commercially available products such as those named DESMOPAN (Bayer AG) or ELASTOLLAN (Elastogran AG), 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 10% inorganic filler (CaCO)₃) And an additive.

PTS-THERMOPRENE-65A60^*807: hardness 67 Shore A, density 1.03g/cm³

A compound consisting of: TPV masterbatch (EPDM-X +/PP), thermoplastic polyether block amide (PEBA) at a content of 40%, hardness 25 Shore D, for example a commercial product named PEBAX (Atofina), 10% MBS (methacrylate-butadiene-styrene) core-shell modifier, 10% inorganic filler (CaCO)₃) And an additive.

Comparative example

PTS-UNIPRENE-7100-55^*9000: hardness 61 Shore A, density 0.93g/cm³

A compound consisting of: TPV master batch, thermoplastic polyolefin (PP) at a content of 7%, and additives.

PTS-THERMOFLEX-VP/S3005/121^*9007(═ mixture according to DE 19845235C 2): hardness 70 Shore A, density 1.17g/cm³

A compound consisting of: high molecular weight functionalized and non-functionalized SEBS block copolymer, 15% plasticizer oil, 40% content of thermoplastic polyetherester elastomer (TPE-E), 20% inorganic filler (CaCO)₃) And an additive.

The complex was prepared under the conditions mentioned in table 1.

Table 1: injection molding parameters for test piece preparation

Material 1. component (polyacetal) material 2. component:

HOSTAFORM C9021，S9064，S9244 PTS-THERMOPRENE，

UNIPRENE，THERMOFLEX

pre-drying temperature: 80[ ° C ] pre-drying temperature: 80 deg.C

Pre-drying time: 3[ h ] Pre-drying time: 2[ h ]

Parameter

Temperature of the die: 70[ ] mold temperature: 20-40 deg.C

A hot channel distributor: 200 ℃ 250[ ° C ]

A hot channel silo: 200 ℃ 250[ ° C ]

Heating zone 5 (nozzle): 200[ deg. ] C heating zone 5 (nozzle): 200 ℃ 250[ ° C ]

Heating zone 4: 200[ ] heating zone 4: 190[ ° C ]

Heating zone 3: 200[ ] heating zone 3: 190[ ° C ]

Heating zone 2: 200[ ] heating zone 2: 190[ ° C ]

Heating zone 1 (hopper): 190[ ° c ] heating zone 1 (hopper): 190[ ° C ]

Injection pressure: 900-1000[ bar ] injection pressure: 350-1100[ bar ]

Injection rate: 40-60[ cm ]³/s]Injection rate: 50-100 cm³/s]

Injection time (measured value): 1.7-2.1[ s ] injection time (found): 0.3-1.0[ s ]

Switching points are as follows: 4-6[ cm ]³]Switching points are as follows: 2-6[ cm ]³]

Maintaining the pressure 1: 750[ bar ] holding pressure 1: 0-600[ bar ]

Holding pressure time 1: 3-5[ s ] holding pressure time 1: 0-4[ s ]

Residual cooling time: 6-10[ s ] residual cooling time: 15-35[ s ]

Back pressure (staudrock): 70[ bar ] back pressure: 20[ bar ]

Decompression: 4[ cm ] of³]Decompression: 2[ cm ] of³]

Screw rotation speed: 25[ min ]^-1]Screw rotation speed: 15[ min ]¹]

Measurement method for determining the bond strength between a hard component and a soft component

To assess the adhesion, a peel test piece was used. These test pieces were prepared on a multicomponent injection molding machine having a locking force of 1000kN (model Arburg Allrounder, 420V1000-350/150, manufacturer Arburg, D72290 Lo β burg). The soft component is injected centrally through the perforations in the hard component. This results in a symmetrical flow path. Test pieces were prepared according to the core pull back (kernruckzug) process using a two-component (2K) die to create the optimum conditions for joint strength. The geometry of the test piece was a frame of 130X 100X 3mm dimensions consisting of polyacetal (hard component) over which a soft component of modified TPV was overmolded in a planar manner. The soft component was a lip having a thickness of 2mm and a length of 115mm and a width of 35 mm.

Fig. 1a, b show a front view and a side view of a test piece P. The hard component forming the frame is indicated by H and the lip, which consists of the soft component, is indicated by W.

Fig. 2 shows a rear view, in which the central perforation B in the hard component H is additionally visible.

The principle test for the joint strength between the hard and soft components is based on a standardized test method according to DIN EN 1464 roll peel test. This test method describes the "determination of the peel resistance of high strength adhesive joints (klebengen)" and is based on metal adhesive joints. The specimen geometry used differs from DIN EN 1464. The roll peel test apparatus described in DIN EN 1464, which was installed into a tensile tester, had a slightly improved roll length due to the specimen size to allow placement of the specimen.

To keep the bending influence of the hard component low at high joint strength during the peeling process, the wall thickness of this component is designed to be 3 mm. The wall thickness of the soft component is 2mm, a dimension which is often customary in practice for flat overmolding, with the result that a relatively high contact temperature is ensured during overmolding of the hard component. The stripping process for the soft component was carried out according to DIN EN 1464 at an angle of 90 ° to the joint surface. The parameters for the joint strength obtained from the 90 ° roll peel test are given as the peel resistance in units of [ N/mm ]:

peel resistance [ N/mm ] -peel force [ N ]/sample width [ mm ]

Evaluation software of tensile tester calculates minimum peel force F_minMaximum peel force F_mdxAnd average peel force F_AverageThe numerical value of (c). The average peel force was taken as a measure of the assessment of the bond strength. The average peel resistance was calculated by dividing the value of the average peel force by the width of the specimen of 35 mm.

The values of the compression set at 70 and 100 ℃ of the elastomeric component are determined in accordance with DIN ISO 815. Type B test pieces having a diameter of 13. + -. 0.5mm and a thickness of 6.3. + -. 0.3mm were used.

Definition of Material joining/adhesion factor

Without joining	Non-adhesive, non-composite part release	1
			Bonding	Slightly adherent, soft component remaining unbonded to hard component	2
Adhesion-cohesion	Good adhesion, firm (cohesive) engagement of the soft and hard components, but incomplete	3
			Cohesion	Very good adhesion, firm bond of soft component with hard component over the whole surface, and interruption of peel-off inside soft component	4
Cohesion > Material Strength (K > MF)	The bonding strength is higher than the material strength; inseparable bonding, peeling no longer being possible, the soft component falling off before peeling begins	5

Peel resistance alone cannot generally be considered for adhesion assessment. The "type of fracture" is also important. The peel resistance is therefore also lower than in the case of relatively hard TPV types (having a generally relatively high breaking strength), in particular in the case of relatively soft TPV types or in the case of types having a relatively low breaking strength. TPV materials with low breaking strength and thus low "peel force" were included in the study. These "peel forces" are often not peel forces, but rather fracture forces. Such a situation is indicated by the adhesion factor 5. Table 2 shows the results of peel resistance and adhesion factor for the examples.

In general, good to very good joint strengths were achieved with the materials of the invention for all polyacetals tested.

In many cases, cohesive fracture or joint strengths higher than the material strength of the soft component of the TPV are achieved. In addition to the properties described above, such as relatively low residual compression set and improved chemical resistance to fats and oils, the known composites according to the prior art using SEBS (comparative example PTS-THERMOFLEX) do not have these properties. This inventive material group therefore opens up new fields of application, in particular in the engine compartment of a motor vehicle.

Claims (21)

1. A composite comprising at least one polyacetal and at least one modified thermoplastic vulcanizate (TPV) joined to one another by adhesive or cohesive means, which composite is formed by a polyacetal molding which has been partly or completely coated with the modified TPV elastomer or onto which one or more moldings composed of the modified TPV have been directly molded, wherein the modified TPV elastomer is a compound having a hardness of from 30 to 90 shore a and comprising:

a) 2-75 wt.% of a fully or partially crosslinked ethylene-propylene-diene rubber (EPDM) in a matrix of 1-50 wt.% of a polyolefin, and 0.05-10 wt.% of a stabilizer and/or crosslinking assistant,

b)1 to 30 wt% of at least one compatibilizer, and

c)10-70 wt% of a non-olefinic thermoplastic material,

wherein the wt% data are based on the total weight of the TPV elastomer.

2. The composite of claim 1, wherein the modified TPV elastomer has a compression set value of < 65% after 24 hours at 70 ℃.

3. The composite of claim 1 or 2, wherein the peel resistance is at least 0.5N/mm.

4. The composite of claim 1 or 2, wherein as polyacetal a polyoxymethylene copolymer is used.

5. The composite of claim 1 or 2, wherein the modified TPV elastomer further comprises up to 50 wt% of a plasticizer oil and/or up to 50 wt% of an organic and/or inorganic filler or reinforcing material.

6. The composite of claim 1 or 2, wherein the non-olefinic thermoplastic material is selected from the group consisting of thermoplastic polyester urethane elastomers, thermoplastic polyether urethane elastomers, thermoplastic polyesters, thermoplastic polyester ester elastomers, thermoplastic polyether amide elastomers, thermoplastic polyamides, thermoplastic polycarbonates, thermoplastic polyacrylates, acrylate rubbers, styrene-acrylonitrile-acrylate rubbers (ASA).

7. The composite of claim 1 or 2 wherein the matrix of EPDM rubber is polypropylene.

8. The composite of claim 1 or 2, wherein component a) is free of unreacted crosslinker residues, or the residual content of unreacted crosslinker is less than 0.1 wt.%, based on the total weight of the TPV elastomer.

9. The composite according to claim 1 or 2, wherein the compatibilizers b) used are functionalized styrene-olefin block copolymers, methacrylate-butadiene-styrene (MBS), MABS (methyl methacrylate-acrylonitrile-butadiene-styrene), functionalized EPDM or ethylene-propylene rubber (EPM) and/or functionalized polyolefins.

10. The composite of claim 1 or 2, wherein the composite is in the form of a molded part composed of polyacetal, which has been completely or partially coated with the modified TPV elastomer.

11. The composite body according to claim 1 or 2, wherein the composite body is in the form of a molding composed of polyacetal, onto which at least one further molding composed of the modified TPV elastomer has been molded.

12. The composite of claim 1 or 2, wherein the composite consists of a polyacetal molding and an injection-applied modified TPV elastomer.

13. The complex of claim 1 or 2, wherein the complex is comprised of: a molding consisting of the modified TPV elastomer and at least one injection-applied polyacetal molding.

14. Process for the preparation of a composite of polyacetal and at least one modified TPV elastomer according to any of claims 1 to 11, wherein a molding composed of polyacetal is first molded and then a coating composed of the modified TPV elastomer or at least one molding is injection-molded onto it, wherein the modified TPV elastomer used is a compound having a hardness of from 30 to 90 shore a and comprising: 2-75% by weight of a fully or partially crosslinked ethylene-propylene-diene rubber (EPDM) in a matrix of 1-50% by weight of a polyolefin, and 0.05-10% by weight of a stabilizer and/or crosslinking assistant; 1-30 wt% of at least one compatibilizer; and 10 to 70 wt% of a non-olefinic thermoplastic material, wherein the wt% data are based on the total weight of the TPV elastomer, and the polyacetal is thus adhesively or cohesively engaged with the modified TPV.

15. Process for the preparation of a composite of polyacetal and at least one modified TPV elastomer according to any of claims 1 to 11, wherein a molded part consisting of the modified TPV is first molded, wherein the modified TPV elastomer used is a compound having a hardness of from 30 to 90 shore a and comprising: 2-75% by weight of a fully or partially crosslinked ethylene-propylene-diene rubber (EPDM) in a matrix of 1-50% by weight of a polyolefin, and 0.05-10% by weight of a stabilizer and/or crosslinking assistant; 1-30 wt% of at least one compatibilizer; and 10 to 70 wt% of a non-olefinic thermoplastic material, wherein the wt% data are based on the total weight of the TPV elastomer, and then injection molding a coating or at least one molded part consisting of a polyacetal onto a molded part consisting of the modified TPV elastomer, and the polyacetal being thus adhesively or cohesively joined to the modified TPV.

16. The process of claim 14 or 15, wherein the process is carried out as a multi-component injection molding process.

17. The process as claimed in claim 14, wherein the process is carried out in a mold in a multi-component injection molding process, wherein a molding composed of polyacetal is preheated to a temperature in the range from 80 ℃ to approximately below its melting point before applying the modified TPV elastomer by injection molding, the temperature of the material of the modified TPV during the application of injection molding to the molding composed of polyacetal is 170-270 ℃, and the temperature of the mold is adjusted to a temperature in the range from 20 to 140 ℃.

18. The process as claimed in claim 15, wherein the process is carried out in a mold in a multi-component injection molding process, wherein the molding composed of the modified TPV is preheated to a temperature in the range from 20 to 80 ℃ before the polyacetal is applied by injection molding, the mass temperature of the polyacetal during the application of the injection molding to the molding composed of the modified TPV is 170-270 ℃, and the mold is tempered to a temperature in the range from 20 to 140 ℃.

19. Use of a composite body according to any one of claims 1 to 13 as a functional component with integrated sealing and damping properties.

20. Use of a composite body according to any one of claims 1 to 13 as a functional component in the engine compartment of a motor vehicle.

Use of a TPV elastomer comprising the following components for the preparation of a composite body according to any one of claims 1 to 13:

a) 2-75% by weight of a fully or partially crosslinked ethylene-propylene-diene rubber (EPDM) in a matrix of 1-50% by weight of a polyolefin, to which 0.05-10% by weight of a stabilizer and/or crosslinking assistant are added, and

b)1 to 30 wt% of at least one compatibilizer, and

c)10-70 wt% of a non-olefinic thermoplastic material,

wherein the wt% data are based on the total weight of the TPV elastomer.