Polymer compositions and molded articles with increased resistance to hydrolysis and improved comparative tracking index

Abstract

A polymer composition for applications requiring increased hydrolytic stability and / or improved comparative tracking index, the polymer composition comprising at least one semi-aromatic polyester resin, at least one epoxy-containing compound, at least one bis-lactam, and at least one phosphorus-containing compound.

Description

[Technical Field]

[0001] The present invention relates to polymer compositions, molded articles, electronic or electrical devices, methods for making molded articles, and the use of the polymer compositions disclosed herein to increase the hydrolytic stability and / or improve the comparative tracking index rating of articles made therefrom according to the independent claims. [Background technology]

[0002] Polycondensation polymers, such as polyesters, tend to degrade through hydrolysis under humid conditions and at elevated temperatures. This type of condition primarily occurs during thermomechanical processing of the polymer, which involves the simultaneous presence of heat and moisture, but can also occur during subsequent use of the resulting product. Hydrolysis of polyesters results in polymers with reduced molecular weight and a decrease in melt viscosity, which simultaneously impairs the polymer's mechanical properties. This effect significantly limits the usefulness of polyesters and further incurs high drying costs before polymer processing. Therefore, there is a growing demand for polyesters as engineering thermoplastics characterized by higher resistance to hydrolysis compared to currently available compositions or those described in the prior art.

[0003] Chain extenders are used to restore the mechanical and rheological properties lost due to hydrolytic degradation during thermomechanical processing. Chain extenders are multifunctional compounds that link the end groups of polymer segments together, resulting in higher molecular weight polymers. The reactivity of the chain extender must be high enough that the reaction occurs within a short time, preferably fast enough to carry out this process during extrusion. Numerous chain extenders with different types of reactivity have been developed for polyesters in the past and are known in the prior art.

[0004] For example, WO 98 / 47940 describes a difunctional caprolactam chain extender for producing high molecular weight polyesters. Similarly, U.S. Pat. No. 3,657,191 discloses a composition containing a linear polyester with terminal epoxy groups and a bis-epoxy compound to increase the molecular weight of the polyester. Because the reactivity of these chain extenders with the carboxyl end groups of the polyester is very high under extrusion conditions, such compounds often suffer from the drawback of causing branched products and / or significant rapid molecular weight growth during extrusion. This is particularly true when these chain extenders are incorporated at the high levels required by current hydrolysis resistance requirements. Naturally, the often unpredictable viscosity increase associated with molecular weight growth also has a detrimental effect on performance manufacturing operations such as injection molding. Furthermore, the stabilizing effect is based on the initial increase in molecular weight due to chain extension, rather than hydrolysis protection that is also present in the final product and throughout its lifetime.

[0005] Polyesters are often reinforced with reinforcing agents such as glass fibers to extend their range of applications. However, this is detrimental to their electrical insulating properties and promotes electrical tracking. Electrical tracking is the formation of conductive paths on the surface of a polymer under certain conditions and at certain voltages. Electrical tracking within a polymer can cause fires and / or damage to components. Therefore, resistance to electrical tracking is often an important safety requirement for materials used in certain electrical or electronic applications. A common way to report the electrical tracking resistance of a polymer is by its comparative tracking index rating (CTI).

[0006] For example, as disclosed in European Patent No. 3,323,854, polybutylene terephthalate (PBT) resin itself has a very high comparative tracking index (CTI) of 600 V. However, when PBT is compounded with various fillers, such as stabilizers, flame retardants, or reinforcing glass fibers, to improve mechanical properties, its tracking resistance decreases significantly depending on the amount of filler added, to, for example, 325 V or less. However, some applications may require a material with a higher comparative tracking index. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to overcome these and other drawbacks of the prior art, and in particular to provide polymer compositions and molded articles comprising such polymer compositions characterized by increased hydrolytic stability and / or improved tracking resistance. In particular, the present invention aims to provide semi-aromatic polyester resins with improved hydrolytic stability and improved tracking resistance. It is a further object of the present invention to provide electronic or electrical devices comprising or consisting essentially of the polymer compositions disclosed herein, and to propose the use of the polymer compositions disclosed herein to increase the hydrolytic stability and / or improve the comparative tracking index rating of articles made therefrom. [Means for solving the problem]

[0008] These and other objects are solved by the polymer composition, the molded article, the electronic or electrical device, the manufacturing method and the use of the polymer composition disclosed herein according to the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0009] The polymer composition according to the present invention comprises at least one semi-aromatic polyester resin, at least one epoxy-containing compound, at least one bis-lactam, and at least one phosphorus-containing compound. DETAILED DESCRIPTION OF THE INVENTION

[0010] As used herein, an epoxy-containing compound is understood to be a compound containing at least one epoxide functional group. In particular, the epoxy-containing compound has a molecular weight of less than 3000 g / mol, preferably less than 1500 g / mol, and is not a polymer.

[0011] Preferred epoxy-containing compounds contain at least three epoxy groups per compound molecule, more preferably at least four epoxy groups per compound molecule, and most preferably at least six epoxy groups per compound molecule. The epoxy-containing compounds may be polymeric or non-polymeric, with non-polymeric being preferred.

[0012] Semi-aromatic polyesters, i.e., polyesters constructed from one aromatic and one aliphatic monomer, are known to those skilled in the art and can generally be described according to the following structural formula (1):

[0013] [ka]

[0014] As known to those skilled in the art, lactams are cyclic amides. The lactam structural motif can be represented according to the following structural formula (2):

[0015] [ka]

[0016] In the illustrated structural formula (1), n ​​indicates the size of the lactam ring, and n is typically an integer of 1 to 5. The resulting lactams are called α-lactam (3-membered ring), β-lactam (4-membered ring), γ-lactam (5-membered ring), δ-lactam (6-membered ring), and ε-lactam (7-membered ring), respectively.

[0017] A bis-lactam is therefore understood to be any compound having the formula (3).

[0018] [ka]

[0019] where n is an integer from 1 to 15, preferably 4 to 10, most preferably 5, and R is any functional group or residue, particularly a carbonyl group, that links the lactam rings. It is also contemplated that at least one of the lactam rings of the bis-lactam may be substituted and / or fused (condensed) to an additional ring. The synthesis of compounds according to formula (3) is described in WO 98 / 47940.

[0020] Specific representative examples of bis-lactams that may be used in accordance with the present invention are the bis-N-acyllactams having formula (4).

[0021] [ka]

[0022] where n is an integer from 1 to 15, preferably 4 to 10, most preferably 5, and A is selected from alkyl groups, such as alkylenediamines, especially hexamethylenediamine, or aromatic groups. The synthesis of compounds according to formula (4) is described in EP 0 286 253.

[0023] As used herein, phosphorus-containing compounds are understood to be in particular metal phosphates, metal phosphonates or metal phosphinates, preferably metal phosphates. In particular, the metal phosphate for use in the present invention is calcium hydrogen phosphate.

[0024] Surprisingly, it has been found that such polymer compositions confer improved hydrolytic stability and excellent comparative tracking indexes to semi-aromatic polyester resins. This is unexpected, especially with regard to hydrolytic stability, because previous publications, such as EP 2 184 311, have reported that the use of carbonyl bis-caprolactam and other carbonyl lactams in polyesters results in an increased hydrolysis rate rather than an improvement in the hydrolytic stability of the respective polyester films. Conversely, the present inventors have found that the use of bis-lactams, particularly N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide) (hereinafter "CBA"), does not prevent the production of polyesters with improved hydrolytic stability, and furthermore, the use of CBA is useful for producing polyesters with improved tracking resistance.

[0025] Without wishing to be bound by theory, addition of a carboxylic acid group to an epoxy group results in the formation of the respective hydroxyalkyl ester, the hydroxyl group of which can then be trapped by reaction with one or both of a bis-lactam and a metal phosphate.

[0026] In a preferred embodiment of the polymer composition according to the present invention, at least one of the epoxy-containing compounds is an epoxidized fatty acid ester.

[0027] The use of epoxidized fatty acid esters is preferred because these compounds are not suspected of being toxic, are characterized by high temperature stability and migration behavior in the polymer matrix, and can be adjusted via the acid used. Furthermore, their use is also favorable from the standpoint of sustainability and environmental protection, since they are based on renewable raw materials.

[0028] The fatty acid ester of the epoxidized fatty acid ester may preferably be selected from linseed oil, soybean oil, sunflower seed oil, safflower oil, hempseed oil, tung oil, oiticica oil, corn oil, sesame oil, cottonseed oil, castor oil, olive oil, peanut oil, rapeseed oil, coconut oil, babassu oil, palm oil, and fish oil. Most preferably, the epoxidized fatty acid ester is epoxidized linseed oil. Epoxidized linseed oil may be represented by the following exemplary structure (5):

[0029] [ka]

[0030] Epoxidized linseed oil (ELO; CAS number 8016-11-3) is available, for example, from Valtris Specialty Chemicals under the trade name Lankroflex™ L.

[0031] Epoxidized linseed oil has been found to be particularly suitable and effective in improving the hydrolytic stability of semi-aromatic polyester resins while enabling excellent comparative tracking resistance indices.

[0032] In a preferred embodiment of the polymer composition according to the present invention, at least one of the bis-lactams in the polymer composition is carbonyl-bis-caprolactam or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), or both. CBA (CAS No. 5888-87-9) is readily available and sold as a polymerization activator by Bruggemann under the trade name Bruggolen®. It is in the form of pellets that melt above 70°C, allowing for dust-free and safe processing.

[0033] In a preferred embodiment, the polymer composition disclosed herein comprises at least one semi-aromatic polyester resin selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and copolyesters thereof; the at least one epoxy-containing compound is at least one epoxidized fatty acid ester; the at least one bis-lactam is one or both of carbonyl-bis-caprolactam and N,N′-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide); and the at least one phosphorus-containing compound is one or both of calcium hydrogen phosphate and hydroxyapatite.

[0034] Such polymer compositions are characterized by both very high tracking resistance and excellent hydrolytic stability.

[0035] In one embodiment of the polymer composition disclosed herein, the at least one semi-aromatic polyester resin is not recycled polyethylene terephthalate (RPET). In other words, the polymer composition is substantially free of recycled polyethylene terephthalate (RPET).

[0036] It is particularly preferred when the polymer composition comprises epoxidized linseed oil, N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide) and calcium hydrogen phosphate.

[0037] As will be described in detail in the comparative experiments, a polymer composition containing epoxidized linseed oil, N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide) (CBA), and calcium hydrogen phosphate exhibits particularly good hydrolysis resistance and tracking resistance.

[0038] In preferred embodiments of the polymer compositions disclosed herein, the at least one phosphorus-containing compound is selected from the group consisting of metal phosphates, metal phosphonates, and metal phosphinates. In particularly preferred embodiments of the polymer compositions disclosed herein, the phosphorus-containing compound is at least one of calcium hydrogen phosphate and hydroxyapatite.

[0039] The total amount of epoxy-containing compounds in the polymer composition can be 0.1 to 5 weight percent based on the total weight of the polymer composition. Preferably, the total amount of epoxy-containing compounds in the polymer composition is 0.5 to 3 weight percent based on the total weight of the polymer composition. In particular, the total amount of epoxidized fatty acid esters in the polymer composition can be 0.1 to 5 weight percent, preferably 0.5 to 3 weight percent, based on the total weight of the polymer composition.

[0040] Within the above range, a significant chain extension effect occurs without the tendency for gel formation to become uncontrollable. Additionally or alternatively, the total amount of bis-lactams in the polymer composition can be 0.1 to 5 weight percent based on the total weight of the polymer composition. Preferably, the total amount of bis-lactams in the polymer composition is 0.5 to 2 weight percent based on the total weight of the polymer composition. In particular, the total amount of one or both of carbonyl-bis-caprolactam and N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide) in the polymer composition can be 0.1 to 5 weight percent, preferably 0.5 to 2 weight percent, based on the total weight of the polymer composition.

[0041] Below 0.1 weight percent the effect is too small, and the resulting amount above 5 weight percent results in gelation and a rapid increase in viscosity during extrusion. In particular, it has been found that the performance of the polymer compositions according to the invention, i.e., hydrolytic stability and comparative tracking index (CTI) rating, is best when the total amount of bis-lactam in the polymer composition is between 0.5 and 2 weight percent, based on the total weight of the polymer composition, since it has been found that the comparative tracking index (CTI) rating of the resulting polymer composition is particularly poor at higher bis-lactam contents.

[0042] Additionally or alternatively, the total amount of phosphorus-containing compounds in the polymer composition can be 0.1 to 5 weight percent based on the total weight of the polymer composition. Preferably, the total amount of phosphorus-containing compounds in the polymer composition is 0.1 to 2.5 weight percent based on the total weight of the polymer composition. In particular, the total amount of calcium hydrogen phosphate and / or hydroxyapatite in the polymer composition can be 0.1 to 5 weight percent, preferably 0.1 to 2.5 weight percent, based on the total weight of the polymer composition.

[0043] The at least one semi-aromatic polyester resin, i.e., the total semi-aromatic polyester resins included in the polymer composition, may be present in an amount of 40 to 90 weight percent, preferably 50 to 80 weight percent, based on the total weight of the polymer composition.

[0044] The above amount ranges allow for additional fillers and additives to be added as needed in amounts necessary for them to be effective.

[0045] The semi-aromatic polyesters used with the present invention are generally prepared by mixing an aromatic dicarboxylic acid, generally having from 8 to 14 carbon atoms, with neopentyl glycol, cyclohexanedimethanol and a copolymer of the formula HO(CH2) n The copolymer includes a condensation product of hydroxypropyl methyl ether (OH) (wherein n is an integer of 2 to 10) with at least one glycol selected from the group consisting of aliphatic glycols.

[0046] Preferred semi-aromatic polyester resins include polyesters selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexylenedimethylene terephthalate (PCT), polytrimethylene terephthalate (PTT), and copolyesters thereof.

[0047] The term "copolyester" refers to a polyester produced by the polymerization of a first monomer with an additional comonomer, which may be a diacid and / or diol component, thereby producing a diacid and / or diol modification.

[0048] Most preferably, the at least one semi-aromatic polyester resin is selected from the group consisting of polyethylene terephthalate (PET) homopolymer, polybutylene terephthalate (PBT) homopolymer, polyethylene terephthalate / polybutylene terephthalate copolymer, polyethylene terephthalate copolymer, polybutylene terephthalate copolymer, blends of polyethylene terephthalate and polybutylene terephthalate and / or mixtures thereof.

[0049] These preferred polyesters are particularly preferred from the viewpoint of their compatibility with electrical and electronic parts, which generally have a good balance of properties, moldability and economic efficiency, and have heat resistance and heat aging resistance.

[0050] The polymer composition may further comprise at least one reinforcing agent. The reinforcing agent may be present in the polymer composition in an amount of preferably 5 to 80 weight percent, based on the total weight of the polymer composition. The reinforcing agent may be present in the polymer composition in an amount of more preferably 10 to 50 weight percent, and most preferably 25 to 40 weight percent, based on the total weight of the polymer composition. A high content of reinforcing agent in the polymer composition, especially 50 weight percent or more, is particularly suitable when the polymer composition is used in a composite material that is not injection molded.

[0051] Preferably, the reinforcing agent is selected from the group consisting of mineral fillers and natural fillers. In particular, the mineral filler may be at least one of whiskers, kaolin, calcined kaolin, wollastonite, talc, chalk, glass fiber, glass beads, amorphous silica, asbestos, calcium silicate, calcium metasilicate, magnesium carbonate, powdered quartz, mica, barium sulfate, and feldspar. Most preferably, the mineral filler may be glass fiber. The natural filler may preferably be kenaf.

[0052] Fiber-reinforced polyesters have higher strength at all temperatures compared to unreinforced polyester matrices. The thermomechanical properties of the polymer compositions disclosed herein, particularly tensile strength and modulus, were observed to increase as the fiber volume content increased up to 50 weight percent based on the total weight of the polymer composition. However, these properties decreased at fiber contents higher than 50 weight percent based on the total weight of the polymer composition. Meanwhile, tensile elongation and impact energy values ​​decreased with increasing fiber content. Overall, the addition of reinforcing agents in an amount of 10 to 50 weight percent based on the total weight of the polymer composition constitutes an appropriate range for effectively improving the thermomechanical properties of the polymer compositions disclosed herein. This range can even be extended to 5 to 80 weight percent based on the total weight of the polymer composition for composites not intended for injection molding, such as profile or film extrusion, pultrusion, prepreg, vacuum molding, or compression molding.

[0053] The glass fibers used with the polymer compositions disclosed herein may be conventional glass fibers known in the art. There are no particular limitations on the cut length, diameter, or shape of the glass fibers. For example, the glass fibers may be cylindrical fibers, cocoon-shaped fibers, or fibers with elliptical cross sections. There are also no particular limitations on the glass cutting method used to cut the glass strands or glass rovings into chopped strands of a predetermined length.

[0054] There is no particular limitation on the type of glass used, but from the viewpoint of quality, it is particularly preferable to use either E glass or corrosion-resistant glass containing zirconium element in the glass composition.

[0055] In addition, in order to improve the interfacial properties between the glass fiber and the resin matrix, it is preferable to use glass fiber that has been surface-treated with an organic treatment agent (surface treatment agent) such as a silane compound including an aminosilane compound or an epoxy compound. There are no particular restrictions on this surface treatment agent, and conventional surface treatment agents can be used.

[0056] In one embodiment of the polymer composition disclosed herein, the polymer composition does not contain glass fibers, i.e., the polymer composition is substantially free of glass fibers. In one embodiment of the polymer composition disclosed herein, the at least one semi-aromatic polyester resin is not recycled polyethylene terephthalate (RPET), and the polymer composition is free of glass fibers. In other words, the polymer composition is substantially free of recycled polyethylene terephthalate (RPET) and is substantially free of glass fibers.

[0057] In general, the polymer compositions disclosed herein, which comprise a combination of at least one epoxy-containing compound and at least one bis-lactam, are already characterized by relatively high impact strength, which can be further increased by the use of toughening agents known per se.

[0058] In some embodiments, the polymer composition further comprises 0.5 to 15 weight percent of at least one toughening agent, based on the total weight of the polymer composition.

[0059] As used herein, "toughening agent" is understood to be an agent that, when added to a semi-aromatic polyester resin, increases the impact strength of an injection-molded element consisting essentially of said semi-aromatic polyester resin, in particular when the impact strength is measured using the "Charpy Notch Impact Strength Test" according to ISO 179.

[0060] The toughening agents, also known as impact modifiers, may be reactive or non-reactive toughening agents. In some embodiments, the polymer composition may include both reactive and non-reactive toughening agents. Preferably, the polymer composition according to the present invention includes a reactive toughening agent.

[0061] Reactive toughening agents are preferred for toughening polyesters because they form a stable dispersed phase by grafting into the polyester matrix. In contrast, non-reactive toughening agents can be dispersed in polyester resins by intensive compounding, but can coalesce downstream of the compounder.

[0062] Preferably, the reinforcing agent is selected from the group consisting of glass fiber, methacrylate-butadiene-styrene copolymer, acrylate elastomer, acrylonitrile-styrene-acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, high rubber graft acrylonitrile-butadiene-styrene copolymer, acrylate-olefin copolymer, silicone rubber, silicone-acrylic rubber, ethylene-propylene non-conjugated diene elastomer, acrylonitrile-styrene-ethylene-propylene non-conjugated diene elastomer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, ethylene-n-butyl-acrylate-co-glycidyl methacrylate (EBA-GMA) terpolymer rubber, and combinations thereof. Even more preferably, the toughening agent is selected from the group consisting of methacrylate-butadiene-styrene copolymer, acrylate-olefin copolymer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, ethylene-n-butyl-acrylate-co-glycidyl methacrylate (EBA-GMA) terpolymer rubber, and combinations thereof.

[0063] The above-mentioned toughening agents have proven to be particularly suitable since they are generally readily available and impart particularly high impact strength to the polyester resins as measured according to the "Charpy notch test" (ISO 179).

[0064] The polymer composition may have a comparative tracking index (CTI) rating of at least 450 V. Preferably, the polymer composition has a comparative tracking index (CTI) rating of at least 550 V. In particular, the polymer compositions disclosed herein comprising 5 to 80 weight percent, preferably 10 to 50 weight percent, and most preferably 25 to 40 weight percent glass fibers, based on the total weight of the polymer composition, have a comparative tracking index (CTI) rating of at least 450 V, preferably at least 550 V.

[0065] CTI can be determined using the measurement method specified in IEC (International Electrotechnical Commission) 60112, 3rd Edition. Specifically, CTI is measured using a 0.1% ammonium chloride solution and a platinum electrode. A specified number of drops (100 drops) of this ammonium chloride solution are applied to each test piece, and the voltage at which none of the test pieces (n=S) breaks down is determined and recorded as CTI.

[0066] One or more conventional additives may be added to the polymer compositions disclosed herein. For example, flame retardants and flame retardant synergists may be added to improve flame retardancy. Due to their plasticizing effect, thermal stability, and dual use as nucleating agents in semi-aromatic polyester resins, preferred flame retardants for use with the present invention are phosphorus-containing flame retardants, such as metal phosphates, metal phosphonates, and metal phosphinates. Additionally or alternatively, antioxidants and thermal stabilizers may be added to improve heat resistance. UV stabilizers may be added to reduce degradation and discoloration. Other additives include fillers, inert fillers, viscosity modifiers, nucleating agents, colorants and dyes, lubricants, plasticizers, and mold release agents.

[0067] In certain embodiments, the polymer composition comprises essentially: 40 to 89 percent by weight of at least one semi-aromatic polyester resin, - 5 to 80 weight percent, preferably 10 to 50 weight percent, most preferably 25 to 40 weight percent of at least one reinforcing agent, in particular glass fibers, from 0.1 to 5 percent by weight, preferably from 0.5 to 2 percent by weight, of at least one bis-lactam, in particular carbonyl-bis-caprolactam or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide) or both, 0.1 to 5 weight percent, preferably 0.5 to 3 weight percent, of at least one epoxy-containing compound, in particular at least one epoxidized fatty acid ester, preferably epoxidized linseed oil, and 0.1 to 5 weight percent, preferably 0.1 to 2.5 weight percent, of at least one phosphorus-containing compound, in particular at least one metal phosphate It consists of:

[0068] Optionally, the above embodiments may include an additional 0.5 to 15 weight percent of at least one toughening agent, where again, weight percent refers to the total weight of the polymer composition including the toughening agent.

[0069] Such polymer compositions are characterized by both improved hydrolytic stability and excellent tracking resistance. Furthermore, such polymer compositions are highly stable and resistant to dielectric breakdown, making them suitable for use in the manufacture of electrical or electronic articles exposed to extreme conditions of use.

[0070] The metal phosphate may preferably be at least one of calcium hydrogen phosphate (CaHPO4) and hydroxyapatite (Ca5(PO4)3OH) due to their non-toxicity, generally ready availability, and effectiveness as flame retardants. Furthermore, the inventors have found that the above-mentioned metal phosphates impart higher comparative tracking indexes and improved hydrolytic stability to the polymer compositions disclosed herein.

[0071] This object is further solved by a molded article comprising the polymer composition disclosed herein.

[0072] The term "shaped article" as used herein includes in particular bulk materials intended for melting in an extruder, such bulk materials also known to those skilled in the art under the terms granules or pellets.

[0073] It is often desirable for molded objects or the granules that form them to be colored. For use in electrical applications, for example, to label or classify products, polymer compositions having orange, red, green, blue, dark gray, or black colors are frequently used.

[0074] Thus, the molded article may further comprise one or a combination of organic and inorganic pigments. The pigment may in particular be carbon black.

[0075] Carbon black is preferably added as a pigment to give a dark gray or black color, and the problems that arise after the addition of carbon black, namely, a decrease in the comparative tracking index rating and the occurrence of tracking at lower voltages, are each mitigated by the polymer compositions disclosed herein.

[0076] The molded articles disclosed herein may be used alone as molded granules or may be mixed with other polymers. The granules may be used to produce fibers, films, and coatings, as well as injection-molded or extruded articles, particularly for end-use applications where improved resistance to hydrolysis is desired. However, in certain embodiments of the present invention, the molded articles disclosed herein are not used to produce polyester films.

[0077] The polymer compositions disclosed herein can be molded into shaped articles or parts according to methods known to those skilled in the art, with commonly used molding methods such as injection molding, extrusion molding, press molding, foam molding, blow molding, vacuum molding, injection blow molding, rotational molding, calendar molding, and solution casting being preferred.

[0078] This object is further solved by an electronic or electrical device containing a component comprising or consisting essentially of the polymer composition disclosed herein.

[0079] The electronic or electrical device may be a charging gun, an inverter, a circuit breaker, a sensor, a relay, a solenoid, a high voltage connector and / or a switch.

[0080] The beneficial effects of such articles and electronic or electrical devices are essentially the same as those already described for the polymer compositions disclosed herein.

[0081] The object is further solved by a method for making a shaped article comprising a polymer composition having at least one epoxidized fatty acid ester disclosed herein.

[0082] Generally, the polymer compositions disclosed herein can be obtained by blending all of the component materials using any blending method. The components are preferably mixed to make the mixture as homogeneous as possible. As a specific example, all of the component materials are mixed uniformly using a mixer such as a blender, kneader, or roll extruder to obtain a polymer resin composition. Alternatively, some of the materials may be mixed in a mixer, and then the remaining materials may be added and further mixed until homogeneous. Alternatively, the materials may be dry-blended in advance, melt-kneaded in a heated extruder until homogeneous, extruded into strands, cut to the desired length, and pelletized. The latter method can be particularly used to prepare a masterbatch that can be mixed with more polymer resin at a later stage.

[0083] However, according to the manufacturing method disclosed herein, the epoxidized fatty acid ester, particularly epoxidized linseed oil, and the bis-lactam, particularly carbonyl-bis-caprolactam and / or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), are added to and melted together with at least one semi-aromatic polyester resin disclosed herein. The at least one phosphorus-containing compound present in the polymer composition disclosed herein may be added to a mixture comprising the epoxidized fatty acid ester, the bis-lactam, and the semi-aromatic polyester resin, or may be added to and melted together with at least one semi-aromatic polyester resin disclosed herein.

[0084] Preferably, the epoxidized fatty acid ester and the bis-lactam are premixed with at least one of the at least one semi-aromatic polyester resins of the polymer composition disclosed herein, added, and melted together.

[0085] In this way, a sudden increase in viscosity during extrusion can be particularly effectively avoided, since both compounds are simultaneously present in the extruder and available in the total amount of semi-aromatic polyester resin of the composition.

[0086] This object is further solved by using the polymer compositions disclosed herein to increase the hydrolytic stability and / or improve the comparative tracking index (CTI) rating of articles made therefrom.

[0087] In particular, this object is solved by the use of a polymer composition comprising at least one epoxidized fatty acid ester disclosed herein, at least one of carbonyl-bis-caprolactam and N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), and at least one of calcium hydrogen phosphate and hydroxyapatite to increase the hydrolytic stability and / or improve the comparative tracking index (CTI) rating of articles made therefrom.

[0088] Contrast The following comparative examples are intended to illustrate the inventive effects of the present invention: Unless otherwise indicated, all amounts are based on the total weight of the respective composition.

[0089] [Table 1]

[0090] The materials used in the above comparison are: PBT resin 1: PBT-R1-D0-035, a pure PBT resin with medium viscosity (MFR (250°C / 2.16 kg) 35 g / 10 min, measured by ASTM D1238) available from Sipchem.

[0091] PBT resin 2: PBT-R1-G6-010, a pure PBT resin with high viscosity (MFR (250°C / 2.16 kg) 10 g / 10 min, measured by ASTM D1238) available from Sipchem.

[0092] Glass fiber: ECS 03 T-187H available from Nippon Electric Glass Co., Ltd. Chopped strands from E-glass are designed for reinforcement of engineering thermoplastics such as PBT and PET.

[0093] Antioxidant: the phenolic antioxidant pentaerythritol tetrakis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionate (CAS number 6683-19-8) available from BASF under the trade name Irganox® 1010.

[0094] Mold release agent: PETS L342, pentaerythritol tetrastearate, available from Faci.

[0095] ELO: Epoxidized linseed oil (CAS number 8016-11-3) available from Valtris Specialty Chemicals under the trademark Lankroflex™ L.

[0096] CaHPO4: Highly compressible directly compressible porous dibasic anhydrous calcium phosphate (calcium hydrogen phosphate) available from Sigma Aldrich.

[0097] CBA C20P: Bruggolen® C20P, N,N′-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide (CAS number 5888-87-9), available from Bruggemann.

[0098] method The formulations listed in the table above were investigated for their thermomechanical properties and tracking resistance.

[0099] To melt the compound, a 40 mm twin-screw extruder with a screw design suitable for glass fiber-reinforced PBT compounds was used. The extruder's heating zone temperature profile was 255°C-255°C-255°C-250°C-250°C-250°C (in the conveying direction), the screw speed was 320-420 RPM, and the output was approximately 120-150 kg / h. The mold temperature used to produce the tensile bars by injection molding was set at 90°C.

[0100] The melt flow index (MFI) of the compounds was determined according to ISO 1133 at 250° C. and 5 kg.

[0101] Tensile properties were measured according to ISO 527-2. Hydrolysis resistance was determined by exposing tensile bars in steam for 96 hours using a pressure cooker at 121°C. In the tables below, this test is referred to as the "pressure cooker test" (PCT). The exposed bars were then held at ambient conditions for at least 24 hours, after which tensile properties were determined according to ISO 527-2 as described above. The relative resistance of the formulations to tracking, i.e., comparative tracking index (CTI), was determined according to IEC 60112.

[0102] result When the above formulations are measured according to the methods defined herein, the following values ​​are obtained:

[0103] [Table 2]

[0104] These results demonstrate the improved hydrolytic stability of the formulation "INV" according to the present invention, which contains a combination of epoxidized linseed oil, CBA, and calcium hydrogen phosphate, compared to the reference "REF" and six comparative formulations. Of the six comparative formulations, REF does not contain epoxidized linseed oil, CBA, or calcium hydrogen phosphate; Examples 1-3 contain one of epoxidized linseed oil, CBA, and calcium hydrogen phosphate; and Examples 4-6 contain two of epoxidized linseed oil, CBA, and calcium hydrogen phosphate. As can be seen from the summarized measurements, the addition of only the phosphorus-containing compound calcium phosphate to the reference composition REF in Comparative Example 1 caused a moderate increase in the comparative tracking index (CTI) value, but this addition had no effect on hydrolytic resistance, as the retention of break stress after PCT (96 hours, 121°C) was 89% and 90%, respectively. Similarly, the addition of CBA and ELO in Comparative Examples 2 and 3, respectively, also resulted in an increase in CTI value, but poor retention of break strain after PCT (96 hours, 121°C). The addition of both CBA and calcium phosphate in Comparative Composition 4 increased the CTI value at the expense of hydrolytic stability after PCT (96 hours, 121°C), as evidenced by a decrease in the break strain (retention) value. Similarly, the addition of both ELO and calcium phosphate in Comparative Composition 5 resulted in a significant increase in the CTI value at the expense of hydrolytic stability after PCT (96 hours, 121°C), as evidenced by a significantly decreased break strain (retention) value. In principle, the same is true for the addition of both ELO and CBA in Comparative Composition 6. In contrast, the break stress and break strain values ​​are higher in the inventive composition "INV," especially in the PCT sample. In particular, it can be seen that Comparative Formulation 2, which was characterized by break stress and break strain values ​​similar to those of the INV composition before PCT, exhibited significantly lower break strain values ​​after PCT (96 hours, 121°C). Comparative Formulation 2 also exhibited a significantly lower comparative tracking index compared to the INV composition. In fact, the control composition INV, which, together with comparative composition 5, is characterized by the highest comparative tracking index, showed a significant reduction in the stress at break and strain at break values, especially after PCT (96 hours, 121° C.).Overall, only the compositions according to the invention are characterized by high comparative tracking index (CTI) ratings combined with good hydrolysis resistance, as evidenced by sustained high stress-at-break and strain-at-break values ​​after PCT (96 hours, 121°C).

Claims

1. A polymer composition for applications requiring increased hydrolytic stability and / or improved comparative tracking index, the polymer composition comprising at least one semi-aromatic polyester resin, at least one epoxy-containing compound, at least one bis-lactam, and at least one phosphorus-containing compound.

2. 2. The composition of claim 1, wherein at least one of the epoxy-containing compounds is an epoxidized fatty acid ester, the fatty acid ester preferably being selected from linseed oil, soybean oil, sunflower seed oil, safflower oil, hemp seed oil, tung oil, oiticica oil, corn oil, sesame oil, cottonseed oil, castor oil, olive oil, peanut oil, rapeseed oil, coconut oil, babassu oil, palm oil, fish oil, and most preferably the epoxidized fatty acid ester is epoxidized linseed oil.

3. 3. The composition of claim 1 or 2, wherein at least one of the bis-lactams is carbonyl-bis-caprolactam or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), or both.

4. 10. The composition of any one of the preceding claims, wherein at least one of the phosphorus-containing compounds is selected from the group consisting of metal phosphates, metal phosphonates and metal phosphinates, preferably at least one of calcium hydrogen phosphate and hydroxyapatite.

5. 10. The composition of any one of the preceding claims, wherein the total amount of epoxy-containing compounds, in particular epoxidized fatty acid esters, in the polymer composition is from 0.1 to 5 weight percent, preferably from 0.5 to 3 weight percent, based on the total weight of the polymer composition; and / or the total amount of bis-lactams, in particular carbonyl-bis-caprolactam and one or both of N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), in the polymer composition is from 0.1 to 5 weight percent, preferably from 0.5 to 2 weight percent, based on the total weight of the polymer composition; and / or the total amount of phosphorus-containing compounds, in particular calcium hydrogen phosphate and one or both of hydroxyapatite, in the polymer composition is from 0.1 to 5 weight percent, preferably from 0.1 to 2.5 weight percent, based on the total weight of the polymer composition.

6. 10. The composition of any one of the preceding claims, wherein the at least one semi-aromatic polyester resin is present in an amount of 40 to 90 weight percent, preferably 50 to 80 weight percent, based on the total weight of the polymer composition.

7. 10. The composition of any one of the preceding claims, wherein the at least one semi-aromatic polyester resin is selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexylene dimethylene terephthalate (PCT), polytrimethylene terephthalate (PTT), and copolyesters thereof, preferably polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and copolyesters thereof.

8. - at least one reinforcing agent, preferably in an amount of 5 to 80 weight percent, more preferably 10 to 50 weight percent, and most preferably 25 to 40 weight percent, based on the total weight of the polymer composition; and optionally, from 0.5 to 15 weight percent, based on the total weight of the polymer composition, of at least one toughening agent; 10. The composition of any one of the preceding claims, further comprising:

9. the reinforcing agent is selected from the group consisting of mineral fillers, in particular the mineral filler may be at least one of whiskers, kaolin, calcined kaolin, wollastonite, talc, chalk, glass fibres, glass beads, amorphous silica, asbestos, calcium silicate, calcium metasilicate, magnesium carbonate, powdered quartz, mica, barium sulphate and feldspar, most preferably glass fibres, and natural fillers, in particular kenaf; and / or the reinforcing agent is selected from the group consisting of glass fibers, methacrylate-butadiene-styrene copolymers, acrylate elastomers, acrylonitrile-styrene-acrylate copolymers, acrylonitrile-butadiene-styrene copolymers, high rubber graft acrylonitrile-butadiene-styrene copolymers, acrylate-olefin copolymers, silicone rubbers, silicone-acrylic rubbers, ethylene-propylene non-conjugated diene elastomers, acrylonitrile-styrene-ethylene-propylene non-conjugated diene elastomers, ethylene-methyl methacrylate-glycidyl methacrylate 9. The composition of claim 8, wherein the toughening agent is selected from the group consisting of methacrylate-butadiene-styrene copolymer, acrylate-olefin copolymer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, ethylene-n-butyl-acrylate-co-glycidyl methacrylate (EBA-GMA) terpolymer rubber, and combinations thereof, preferably wherein the toughening agent is selected from the group consisting of methacrylate-butadiene-styrene copolymer, acrylate-olefin copolymer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, ethylene-n-butyl-acrylate-co-glycidyl methacrylate (EBA-GMA) terpolymer rubber, and combinations thereof.

10. 10. The composition according to any one of the preceding claims, in particular claim 9, wherein the polymer composition has a Comparative Tracking Index (CTI) rating, measured according to IEC 60112, of at least 450V, preferably at least 550V.

11. each based on the total weight of the polymer composition - 40 to 89 percent by weight of at least one semi-aromatic polyester resin; - 5 to 80 weight percent, preferably 10 to 50 weight percent, most preferably 25 to 40 weight percent of at least one reinforcing agent, in particular glass fiber; from 0.1 to 5 percent by weight, preferably from 0.5 to 2 percent by weight, of at least one bis-lactam, in particular carbonyl-bis-caprolactam or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), or both, - 0.1 to 5 weight percent, preferably 0.5 to 3 weight percent, of at least one epoxy-containing compound, in particular at least one epoxidized fatty acid ester, preferably epoxidized linseed oil, - 0.1 to 5 weight percent, preferably 0.1 to 2.5 weight percent, of at least one phosphorus-containing compound, in particular at least one metal phosphate, optionally, 0.5 to 15 percent by weight of at least one toughening agent; 10. The composition of any one of the preceding claims, consisting essentially of

12. A shaped article, in particular a bulk material for melting in an extruder, comprising a polymer composition according to any one of claims 1 to 11.

13. An electronic or electrical device containing a component comprising or consisting essentially of the polymer composition of any one of claims 1 to 11.

14. The device of claim 13 , wherein the device is a charging gun, an inverter, a circuit breaker, a sensor, a relay, a solenoid, a high voltage connector, and / or a switch.

15. 12. A method for producing a molded article comprising the polymer composition according to any one of claims 1 to 11, wherein the epoxidized fatty acid ester, in particular epoxidized linseed oil, and the bis-lactam, in particular carbonyl-bis-caprolactam and / or N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), are added and melted together with the at least one semi-aromatic polyester resin, and the at least one phosphorus-containing compound is added to a mixture comprising the epoxidized fatty acid ester, the bis-lactam and the semi-aromatic polyester resin, or is added and melted together with the at least one semi-aromatic polyester resin, preferably the epoxidized fatty acid ester and the bis-lactam are premixed with the at least one semi-aromatic polyester resin, added and melted together.

16. 12. Use of a composition according to any one of claims 1 to 11, said composition comprising at least one epoxidized fatty acid ester, at least one of carbonyl-bis-caprolactam and N,N'-hexane-1,6-diylbis(hexahydro-2-oxo-1H-azepine-1-carboxamide), and at least one of calcium hydrogen phosphate and hydroxyapatite, in particular for increasing the hydrolytic stability and / or improving the comparative tracking index (CTI) rating of an article made therefrom.

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