Foamed glass fiber reinforced thermoplastic composition

Abstract

The present invention relates to a foamed glass fiber reinforced thermoplastic composition comprising, based on the total weight thereof, (a) 30-90% by weight of a thermoplastic polymer matrix, (b) 10-70% by weight of glass fibers and (c) 0.5-20% by weight of an impregnant wherein the foamed glass fiber reinforced thermoplastic composition has a density reduction of at least 30%, wherein the density reduction rate is calculated as (d unfoamed-d foamed) / d unfoamed, where d foamed is the density of the foamed glass fiber reinforced thermoplastic composition, and d unfoamed is the density of the same glass fiber reinforced thermoplastic composition that is not foamed. The invention also relates to a method for producing the foamed glass fiber reinforced thermoplastic composition, and to an article produced from the foamed glass fiber reinforced thermoplastic composition. Due to the low dielectric constant of the foamed glass fiber reinforced thermoplastic composition, the produced articles may be used in a variety of fields and applications, such as in antenna housings or hoods.

Description

[0001] The present invention relates to a foamed glass fiber reinforced thermoplastic composition, a method for producing a foamed glass fiber reinforced thermoplastic composition, and an article produced from the foamed glass fiber reinforced thermoplastic composition. Due to the low dielectric constant of the foamed glass fiber reinforced thermoplastic composition of the present invention, the produced articles can be used in various fields and applications, such as in antenna housings or covers.

[0002] In traditional telecommunication (3G and 4G) applications, antennas and their housings mainly made of plastic materials such as engineering thermoplastics (ETP) meet the market demand for electromagnetic waves to pass through the materials with lower losses, thus enabling high-speed signal connections in each household and public place.

[0003] The frequency range of 4G electromagnetic waves is 3 GHz, and the peak data rate is 1 Gb / s. The dielectric constant Dk of these ETP materials is usually greater than 2.6, and the loss factor Df is greater than 0.005.

[0004] The frequency range of the global new generation 5G telecommunication network is expected to be higher than 20 GHz, and the peak data rate is higher than 20 Gb / s. This means that the dielectric properties of plastic materials such as dielectric constant (Dk) and dielectric loss (Df) need to be reduced to avoid signal losses in high-speed connections.

[0005] The Dk and Df values of currently used plastic materials (PC, PC blends) at high frequencies are not suitable to meet the dielectric property requirements of 5G. Information in the electronics and electrical (E&E) market indicates that compared with the 4G environment, the 5G applications have more stringent requirements for Dk and Df of these materials. In a typical 5G environment, Dk should be less than 3, and Df should be less than 0.005, for example, at a nominal frequency of 1.0 GHz.

[0006] The dielectric (Dk, Df) values of most commonly used ETP-based plastic components are indeed significantly higher than the requirements, and thus are not suitable to meet the dielectric requirements of 5G.

[0007] It seems that increasing the thickness means an increase in the weight of plastic components, which is not preferred in most applications. For example, in terms of physically strenuous work, it causes unsafe or unhealthy ergonomic conditions for personnel.

[0008] It is known in the prior art that materials with inherently low Dk / Df values such as polypropylene (PP) and polyethylene (PE) help to reduce the Dk and Df values of components made therefrom.

[0009] The present invention has found that the dielectric constant of the foamed glass fiber-reinforced thermoplastic composition is lower than that of the unfoamed same glass fiber-reinforced thermoplastic composition. The plastic parts made of such foamed thermoplastic composition contain (air) voids inside, which helps to reduce the Dk / Df value and significantly reduces the weight. Due to the lower density, the lower weight means that the radome or housing parts are lighter and more ergonomic for the construction workers to handle these parts.

[0010] In the context of the present invention, the terms "mass" and "weight" are used interchangeably. The term "mass %" has the same meaning as the term "weight %" or simply "wt %".

[0011] In the context of the present invention, unless otherwise clearly stated, the amount / content of a specific component expressed as a percentage ("%") is by weight.

[0012] In the context of the present invention, the term "degree Celsius" or "°C" is sometimes abbreviated to "C". For example, as known to those skilled in the art, "190C" means "190°C".

[0013] In the context of the present invention, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are also intended to include the plural forms.

[0014] In the context of the present invention, the term "comprising" or "including" also includes the meanings of "comprised of", "substantially including", "consisting of" or "substantially consisting of".

[0015] In the context of the present invention, any numerical values that describe the same aspect / feature of the present invention throughout the present disclosure can be combined together to form a new range. For example, when the amount of a certain component is described in the context as at least 1 wt%, preferably at least 2 wt%, and at most 5%, preferably at most 4 wt%, and specifically 3 wt% in one instance, the amount ranges of 1-2 wt%, 2-3 wt%, 3-4 wt%, 4-5 wt%, 1-5 wt%, 2-4 wt% etc. are inherently disclosed as if they were clearly described in the present invention. For example, when the amount of a certain component is described in the context as in the range of 1-5 wt%, preferably 2-4 wt%, and specifically 3 wt% in one instance, the amount ranges of 1-2 wt%, 2-3 wt%, 3-4 wt%, 4-5 wt% etc. are inherently disclosed as if they were clearly described in the present invention.

[0016] In the present invention, the glass fiber-reinforced thermoplastic composition is a thermoplastic composition reinforced with glass fibers.

[0017] In the present invention, the thermoplastic composition comprises, based on its total weight:

[0018] (a) 30 - 90% by weight of a thermoplastic polymer matrix, and

[0019] (b) 10 - 70% by weight of glass fibers.

[0020] In some cases, the thermoplastic composition further comprises:

[0021] (c) 0.5 - 20% by weight of an impregnating agent, which is non - volatile, has a melting point at least 20 °C lower than the melting point of the thermoplastic polymer matrix, has a viscosity of 2.5 - 100 cS at the application temperature measured according to ASTM D3236 - 15, and is compatible with the thermoplastic polymer matrix.

[0022] In some cases, the thermoplastic composition further comprises:

[0023] (d) 5 - 20% by weight of at least one polyolefin - based elastomer.

[0024] In one aspect of the present invention, there is provided a foamed glass fiber - reinforced thermoplastic composition, which comprises, based on its total weight:

[0025] (a) 30 - 90% by weight of a thermoplastic polymer matrix, and

[0026] (b) 10 - 70% by weight of glass fibers,

[0027] wherein the density of the foamed glass fiber - reinforced thermoplastic composition is reduced by at least 30% based on the density of the same unfoamed glass fiber - reinforced thermoplastic composition. In other words, the density reduction rate of the foamed glass fiber - reinforced thermoplastic composition is at least 30%, where the density reduction rate is calculated according to (d 未发泡 - d 发泡 ) / d 未发泡 , where d 发泡 is the density of the foamed glass fiber - reinforced thermoplastic composition, and d 未发泡 is the density of the same unfoamed glass fiber - reinforced thermoplastic composition.

[0028] According to the present invention, by foaming the unfoamed glass fiber - reinforced thermoplastic composition, the density of the glass fiber - reinforced thermoplastic composition is reduced by at least 30% in percentage. In some cases, the density of the foamed glass fiber - reinforced thermoplastic composition is reduced by at least 35%, preferably at least 40%, more preferably at least 45%, based on the density of the same unfoamed glass fiber - reinforced thermoplastic composition.

[0029] In some cases, the density of the foamed glass fiber-reinforced thermoplastic composition is reduced by up to 70%, preferably up to 65%, more preferably up to 60%, based on the density of the same unfoamed glass fiber-reinforced thermoplastic composition.

[0030] In some cases, the density of the foamed glass fiber-reinforced thermoplastic composition is at most 800 kg / m 3 , preferably at most 700 kg / m 3 , more preferably at most 600 kg / m 3 , and even more preferably at most 500 kg / m 3 .

[0031] In some cases, the Dk value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.0 GHz according to GB12636 is at most 2.50, preferably at most 1.90, more preferably at most 1.80, even more preferably at most 1.70, and still more preferably at most 1.60.

[0032] In some cases, the Dk value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.9 GHz according to GB12636 is at most 2.50, preferably at most 2.10, more preferably at most 2.00, even more preferably at most 1.80, and still more preferably at most 1.70.

[0033] In some cases, the Df value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.0 GHz according to GB12636 is at most 0.0015, preferably at most 0.0014, more preferably at most 0.0013, even more preferably at most 0.0012, and still more preferably at most 0.0011.

[0034] In some cases, the Df value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.9 GHz according to GB12636 is at most 0.0030, preferably at most 0.0028, more preferably at most 0.0026, even more preferably at most 0.0024, and still more preferably at most 0.0023.

[0035] In some cases, the foamed glass fiber-reinforced thermoplastic composition is produced by foaming an unfoamed glass fiber-reinforced thermoplastic composition.

[0036] In some cases, the foamed glass fiber-reinforced thermoplastic composition is produced by foaming an unfoamed glass fiber-reinforced thermoplastic composition via an injection molding foaming (FIM) process or an extrusion foaming process.

[0037] In another aspect of the present invention, there is provided a foamable composition comprising the thermoplastic composition of the present invention and a foaming agent.

[0038] In another aspect of the present invention, there is provided a method for producing a foamed glass fiber-reinforced thermoplastic composition, which comprises the following sequential steps:

[0039] i. Providing a thermoplastic composition and a blowing agent, wherein the thermoplastic composition comprises, based on its total weight:

[0040] (a) 30 - 90 wt% of a thermoplastic polymer matrix, and

[0041] (b) 10 - 70 wt% of glass fibers; and

[0042] ii. Foaming the thermoplastic composition such that the density of the foamed glass fiber-reinforced thermoplastic composition is reduced by at least 30% based on the density of the same unfoamed glass fiber-reinforced thermoplastic composition, in other words, the density reduction rate of the foamed glass fiber-reinforced thermoplastic composition is at least 30%, wherein the density reduction rate is calculated according to (d 未发泡 -d 发泡 ) / d 未发泡 where d 发泡 is the density of the foamed glass fiber-reinforced thermoplastic composition, and d 未发泡 is the density of the same unfoamed glass fiber-reinforced thermoplastic composition.

[0043] In another aspect of the present invention, there is provided an article produced from the foamed glass fiber-reinforced thermoplastic composition of the present invention.

[0044] In another aspect of the present invention, there is provided an article comprising a core layer and two adjacent surface layers, wherein the core layer is produced from the foamed glass fiber-reinforced thermoplastic composition of the present invention, and at least one surface layer is produced from an unfoamed thermoplastic composition.

[0045] In some cases, the article of the present invention is an antenna housing or a radome.

[0046] Thermoplastic polymer

[0047] The glass fiber-reinforced thermoplastic composition of the present invention comprises a thermoplastic polymer matrix. The thermoplastic polymer matrix comprises at least one thermoplastic polymer.

[0048] Suitable examples of the thermoplastic polymer include polyamides such as polyamide 6, polyamide 66 or polyamide 46; polyolefins such as polypropylenes and polyethylenes, including polyolefin homopolymers, copolymers or any blends thereof; polyesters such as polyethylene terephthalate, polybutylene terephthalate; polycarbonate; polyphenylene ether (PPE); polyphenylene sulfide (PPS); polyurethane; and any type of polymer blends and compoundings and any combinations thereof.

[0049] More particularly, polypropylene, polybutylene terephthalate and polyamide 6 can be used.

[0050] In some cases, the thermoplastic polymer is free of phthalates.

[0051] Polypropylene

[0052] In some cases, the thermoplastic polymer matrix of the present invention comprises at least one polypropylene polymer, which may be (a1) a propylene homopolymer, (a2) a random copolymer of propylene and at least one other olefin, (a3) a propylene impact copolymer, (a4) a modified or functionalized propylene homopolymer or copolymer, or a mixture thereof.

[0053] The polypropylene is preferably crystalline. The term "crystalline" generally means that the polymer has an isotactic structure, i.e., it has a high isotactic regularity, for example higher than 95% and preferably higher than 98%.

[0054] The random copolymer typically contains up to about 20 mol%, preferably up to 10 mol%, of other olefins as comonomers to maintain the crystalline properties. The at least one other olefin may be, for example, an α-olefin, especially a 1-olefin having, for example, 2 or 4 - 20 carbon atoms, preferably 4 - 12 carbon atoms, or a cyclic olefin having a double bond in the ring structure (optionally containing more than one ring). Examples of suitable olefins include ethylene, butene, hexene, styrene, cyclopentene and norbornadiene. Preferably, the α-olefin is a 1-olefin having 2, 4, 6 or 8 carbon atoms, and more preferably, the α-olefin is ethylene.

[0055] Preferably, the polypropylene polymer is a propylene impact copolymer, as this results in a favorable combination of stiffness and toughness. Propylene impact copolymers are also known as propylene block copolymers or polypropylene multiphase copolymers. Such materials generally have at least a two-phase structure, which consists of a crystalline propylene-based matrix and a dispersed elastomeric phase, which is typically an ethylene-olefin copolymer such as ethylene-propylene rubber (EPR). These polypropylenes are generally prepared in one or more reactors by the polymerization of propylene in the presence of a catalyst and subsequent polymerization of an ethylene-olefin copolymer such as ethylene-propylene rubber (EPR), but can also be prepared by blending individual components, as is well known to those skilled in the art. The resulting polymer materials are multiphase, but their specific morphology generally depends on the preparation method as well as the monomer type and ratio. In some cases, the polyolefin should have at least one crystalline melting point (Tm) of 120 to 170 °C, where Tm has a heat capacity (dHm) of at least 10 J / g. Tm and dHm are determined by DSC according to ASTM D3418 at a heating rate of 20 °C / min.

[0056] Typically, the impact copolymer contains about 50-95% by mass of a crystalline propylene homopolymer or random copolymer matrix, and about 5-50% by mass of a dispersed copolymer of ethylene and at least one other olefin.

[0057] The amount of the dispersed phase is preferably 10-35% by mass, more preferably 15-30% by mass or 17-25% by mass, of the total amount of the multiphase polymer, in order to achieve a desired stiffness-impact balance in the composition according to the invention.

[0058] The dispersed phase comprises a copolymer of ethylene and at least one other olefin, preferably a C3-C10 α-olefin. Examples of suitable C3-C10 α-olefins include 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene. Preferably, an ethylene-propylene copolymer, also known as ethylene-propylene rubber (EPR), is used as the dispersed phase.

[0059] The amounts of the propylene-based matrix and the dispersed ethylene-olefin copolymer can be determined by NMR, as is well known in the art.

[0060] Preferably, the propylene-based matrix is a propylene homopolymer.

[0061] Preferably, the melt flow index (MFI) (MFIPP) of the propylene-based matrix is at least 30 dg / min and at most 120 dg / min, measured according to ISO 1133 (2.16 kg / 230 °C). The MFIPP can be, for example, at least 40 dg / min, at least 45 dg / min, at least 50 dg / min, at least 55 dg / min or at least 60 dg / min, and / or, for example, at most 110 dg / min, at most 100 dg / min, at most 90 dg / min or at most 80 dg / min, measured according to ISO 1133 (2.16 kg / 230 °C).

[0062] The propylene-based matrix is preferably semi-crystalline, i.e., it is not 100% amorphous nor 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, such as at least 50%, such as at least 60% crystalline and / or, for example, at most 80% crystalline, such as at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. For the purposes of the present invention, the crystallinity of the propylene-based matrix is measured by differential scanning calorimetry (DSC) according to ISO 11357-1 and ISO 11357-3 of 1997, where a scan rate of 10 °C / min, a sample of 5 mg and a second heating curve using 207.1 J / g as the theoretical standard for 100% crystalline material are used.

[0063] The melt flow index (MFIEPR) of the dispersed ethylene-olefin copolymer can be, for example, at least 0.001 dg / min, at least 0.01 dg / min, at least 0.1 dg / min, at least 0.3 dg / min, at least 0.7 dg / min, at least 1 dg / min and / or, for example, at most 30 dg / min, at most 20 dg / min, at most 15 dg / min, at most 10 dg / min, at most 5 dg / min, at most 3 dg / min, as measured according to ISO 1133 (2.16 kg / 230 °C).

[0064] The amount of ethylene in the ethylene-olefin copolymer is preferably in the range of 20 to 80% by weight, more preferably, the amount of ethylene in the ethylene-olefin copolymer is 30 to 70% by weight, more preferably 40 to 65% by weight, more preferably 50 to 65% by weight, even more preferably 55 to 65% by weight, based on the ethylene-olefin copolymer.

[0065] Preferably, the α-olefin in the ethylene-α-olefin copolymer is propylene.

[0066] The MFI of the polypropylene polymer is in the range of 17 to 75 dg / min, preferably in the range of 20 to 60 dg / min, more preferably in the range of 25 to 55 dg / min, even more preferably in the range of 28 to 40 dg / min, as measured according to ISO 1133 (2.16 kg / 230 °C).

[0067] The xylene-soluble fraction of the polypropylene polymer according to the present invention is in the range of 9.3 to 19.6% by weight, preferably in the range of 11.2 to 18.4% by weight, more preferably in the range of 12.4 to 17.4% by weight, measured according to ISO 16152:2005.

[0068] The intrinsic viscosity of the xylene-soluble fraction of polypropylene is preferably in the range of 1.2 to 4.6 dl / g, preferably in the range of 1.8 to 4.0 dl / g, even more preferably in the range of 2.3 to 3.5 dl / g, as measured in decalin at 135 °C according to ISO 1628-1:2009.

[0069] Preferably, the polypropylene has a crystalline melting point (Tm) of 120 to 170 °C, where Tm has a heat capacity (dHm) of at least 10 J / g. Tm and dHm are determined by DSC according to ASTM D3418 at a heating rate of 20 °C / min. In some cases, the polyolefin will be free of phthalates.

[0070] The thermoplastic polymer matrix may also contain modified polypropylene; this generally improves the properties by influencing the glass fiber - polypropylene interaction. Examples of suitable modified polypropylenes are polypropylenes grafted with, for example, unsaturated organic compounds such as carboxylic acids, acid anhydrides, esters, glycidyl esters or salts thereof. Suitable examples include maleic acid, fumaric acid, (meth)acrylic acid, itaconic acid or cinnamic acid or their acid anhydrides, esters or carboxylates. Maleic anhydride is preferably used. The amount of modified polypropylene can vary widely, but for economic reasons, this amount will generally be rather low, for example less than 5% by mass, preferably less than 4, 3, 2 or even 1% by mass (based on the total composition).

[0071] The polypropylene polymers according to the invention can be produced using any conventional techniques known to the person skilled in the art, such as multistage polymerization methods like bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combination thereof. Any conventional catalyst system can be used, such as Ziegler - Natta or metallocene. Such techniques and catalysts are described, for example, in WO06 / 010414; Polypropylene and other Polyolefins by Ser van der Ven, Studies in Polymer Science 7, Elsevier 1990; WO06 / 010414; US4399054 and US4472524. Preferably, polypropylene is prepared using a Ziegler - Natta catalyst.

[0072] Glass fiber

[0073] Generally, glass fibers are glassy cylindrical substances, where their length is significantly longer than the diameter of their cross - section. It is known that adding glass fibers can improve the mechanical properties (such as strength and stiffness) of the polymer matrix. The level of property improvement depends to a large extent on the properties of the glass fibers, such as the diameter, length and surface properties of the glass fibers.

[0074] The thermoplastic composition contains 10 - 70% by mass, preferably 5 - 25% by mass, and more preferably 5 - 20% by mass of glass fibers.

[0075] In some cases, the glass fibers of the present invention have a length of 1 - 50 mm. Compositions containing glass fibers with a length greater than 1 mm are generally referred to as long glass fiber (LGF) reinforced compositions, such as LGF PP compositions.

[0076] In contrast, short glass fiber compositions or blends typically contain fibers with lengths below 1 mm. Such blends are typically prepared by mixing chopped strands of a predetermined length with a thermoplastic polymer in an extruder, during which the glass fibers are dispersed in the molten thermoplastic. The fiber length is reduced due to fiber breakage during this process. When the composition is formed into a product, the fiber size is further reduced.

[0077] For example, long glass fiber-reinforced polymer compositions in the form of pellets or granules can be prepared from continuous lengths of fibers by a sheathing or wire coating method, by crosshead extrusion, or several pultrusion techniques. Using these techniques, strands of fibers impregnated or coated with a polymer are formed; these can then be cut to a certain length, and the pellets or granules thus obtained can be further processed into (semi)-finished products, for example, by injection molding or extrusion methods.

[0078] In the pultrusion method, a bundle of continuous glass filaments is unwound into individual filaments and drawn through an impregnation die into which molten thermoplastic is injected, with the aim of completely wetting and impregnating each filament with the molten thermoplastic. Strands with a diameter of about 3 mm are pulled out of the die and then cooled. Finally, the strands are cut into sections of the desired length. The glass fibers in the sections are typically parallel to each other, and each fiber is individually surrounded by the thermoplastic.

[0079] The sheathing or wire coating method is accomplished without individually wetting the fibers with thermoplastic, but rather by forming a continuous outer sheath (also referred to as a coating or skin / shell) of thermoplastic material around the surface of a continuous multi-filament strand. The sheathed continuous strand is cut into pellets or granules of the desired length, for example, about 10 mm in length, where the fibers are typically parallel to each other and have the same length as the pellets or granules. Such pellets or granules contain a core extending axially and a thermoplastic polymer sheath tightly surrounding the core, where the core contains a plurality of long glass fiber filaments and an impregnating agent, and the sheath is substantially free of the filaments. The LGF pellets are additionally supplied to an injection molding machine or a compression molding machine, and during this molding step, the glass fibers are dispersed within the thermoplastic polymer and formed into a molded (semi)-finished product. The documents EP 0921919 B1 and EP 0994978 B1 describe typical sheathing or wire coating methods. WO2018109118A1 discloses wire-coated LGF pellets.

[0080] The average length of the glass fibers in the composition of the present invention is preferably at least 2 mm to produce higher strength and stiffness, more preferably at least 3, 4, 5 or even 6 mm. Excessively high lengths may cause problems, for example, in processing or in the surface appearance of the molded article, and thus the length of the glass fibers is preferably at most 40 mm, more preferably at most 30, 20 or 15 mm. It has been found that compositions containing fibers with an average length of 0.1 - 10 mm perform best in terms of the mechanical properties, shrinkage and scratch resistance of the molded articles obtained therefrom.

[0081] The diameter of the glass fibers in the composition according to the present invention is not very critical, but very thick fibers may lead to a reduction in mechanical properties and / or lower surface quality. Generally, the diameter is in the range of 5 to 50 μm, preferably 5 to 30 μm, more preferably 8 to 25 μm.

[0082] The amount of glass fibers affects the mechanical properties of the molded articles obtained therefrom, as well as the processing and mold shrinkage behavior and aesthetics, and this amount can be optimized according to the desired property characteristics.

[0083] The filament density of continuous glass multifilament strands can vary within wide limits. Preferably, the continuous multifilament strands can have 500 to 10,000 glass filaments per strand, and more preferably 2,000 to 5,000 glass filaments per strand, because of the high output. The diameter of the glass filaments in the continuous multifilament strands can vary over a wide range. Preferably, the diameter of the glass filaments is in the range of 5 to 50 μm, more preferably 10 to 30 μm, and most preferably 15 to 25 μm. Glass filament diameters outside these ranges tend to result in a reduction in mechanical properties and / or increased wear of the equipment used.

[0084] Impregnant

[0085] In one aspect of the present invention, the glass fiber-reinforced thermoplastic composition of the present invention preferably further comprises a sizing agent.

[0086] The amount of sizing agent applied to the thermoplastic composition depends on the thermoplastic matrix, the size (diameter) of the filaments forming the continuous strands, and the type of sizing on the fiber surface.

[0087] According to the present invention, the amount of sizing agent applied to the thermoplastic composition should be at least 0.5% by mass, preferably at least 2% by mass, more preferably at least 4% by mass, and most preferably at least 6% by mass; but should be at most 20% by mass, preferably at most 18% by mass, more preferably at most 15% by mass, and most preferably at most 12% by mass. A certain minimum amount of sizing agent is needed to help the uniform dispersion of the glass fibers in the thermoplastic polymer matrix during molding, but this amount should not be too high, as an excessive amount of the agent may lead to a reduction in the mechanical properties of the molded article.

[0088] It is found that the lower the viscosity, the less impregnating agent can be applied. For example, in the case where the thermoplastic polymer matrix is a polypropylene homopolymer having a melt index MFI of 25 to 65 g / 10 min (230 °C / 2.16 kg) and the reinforcing long glass filaments have a diameter of 19 microns, it is preferred to apply the impregnating agent in an amount of 2 to 10% by mass to the multifilament strands.

[0089] The impregnating agent used in the present invention is at least one compound compatible with the thermoplastic polymer matrix to be reinforced, enabling it to enhance the dispersion of glass fibers in the thermoplastic polymer matrix during the molding process.

[0090] At the application temperature, the viscosity of the impregnating agent should be at most 100 cS, preferably at most 75 cS, and more preferably at most 25 cS. At the application temperature, the viscosity of the impregnating agent should be at least 2.5 cS, preferably at least 5 cS, and more preferably at least 7 cS. An impregnating agent having a viscosity higher than 100 cS is difficult to apply to continuous glass multifilament strands. A low viscosity is required to promote good wetting properties of the fibers, but an impregnating agent having a viscosity lower than 2.5 cS is difficult to handle, for example, the amount to be applied is difficult to control; and the impregnating agent may become volatile. Without wishing to be bound by any theory, the inventors believe that the impregnation of continuous glass multifilament strands by the impregnating agent without separating or spreading the individual filaments is mainly driven by capillary forces.

[0091] For the purposes of the present invention, unless otherwise specified, the viscosity of the impregnating agent is measured at 160 °C in accordance with ASTM D3236-15 (Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials, Brookfield viscometer model RVDV2, #27 rotor, 5 r / min).

[0092] The melting point of the impregnating agent is at least about 20 °C below the melting point of the thermoplastic matrix. Without wishing to be bound by any theory, the inventors believe that this difference in melting point and thus in freezing or crystallization point also promotes fiber impregnation after applying the thermoplastic sheath and cooling the sheathed strands, as well as fiber dispersion during subsequent molding. Preferably, the impregnating agent has a melting point at least 25 or 30 °C below the melting point of the thermoplastic matrix. For example, when the thermoplastic polymer matrix is polypropylene having a melting point of about 160 °C, the melting point of the impregnating agent can be at most about 140 °C.

[0093] The application temperature is selected such that the desired viscosity range is obtained and is preferably below the autoignition temperature of the impregnating agent. For example, when the matrix is polypropylene, the application temperature of the impregnating agent can be 15 °C to 200 °C.

[0094] According to the present invention, the impregnating agent should be compatible with the thermoplastic polymer to be reinforced and may even be soluble in the polymer. A person skilled in the art can select a suitable combination based on general knowledge and can also find such combinations in the art. Suitable examples of the impregnating agent include low molar mass compounds such as low molar mass or oligomeric polyurethanes, polyesters such as unsaturated polyesters, polycaprolactone, polyethylene terephthalate, poly(α-olefins) such as highly branched polyethylene and polypropylene, polyamides such as nylon and other hydrocarbon resins. Generally speaking, respectively, a polar thermoplastic polymer matrix requires the use of an impregnating agent containing polar functional groups; a non-polar polymer matrix involves the use of an impregnating agent with non-polar characteristics. For example, in order to reinforce polyamide or polyester, the impregnating agent may include low molecular weight polyurethane or polyester such as polycaprolactone. In order to reinforce polypropylene, the impregnating agent may include highly branched poly(α-olefins) such as polyethylene wax, modified low molecular weight polypropylene, mineral oils such as paraffin wax or silicone and any mixture of these compounds. Preferably, the impregnating agent includes highly branched poly(α-olefins), and more preferably, when the thermoplastic polymer to be reinforced is polypropylene, the impregnating agent is highly branched polyethylene wax; the wax is optionally mixed with, for example, 10 to 80% by mass, preferably 20 to 70% by mass of a hydrocarbon oil or wax such as paraffin oil to achieve the desired viscosity level.

[0095] According to the present invention, the impregnating agent is non-volatile and substantially solvent-free. Non-volatile means that the impregnating agent does not evaporate under the application and the applied processing conditions; that is, it has a boiling point or boiling range higher than the processing temperature. In the context of the present application, "substantially solvent-free" means that the impregnating agent contains less than 10% by mass of solvent, preferably less than 5% by mass of solvent. Most preferably, the impregnating agent does not contain any organic solvents.

[0096] Polyolefin-based elastomer

[0097] In one aspect of the present invention, the glass fiber-reinforced thermoplastic composition of the present invention preferably further comprises a polyolefin-based elastomer.

[0098] The polyolefin-based elastomer is preferably selected from the group consisting of ethylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer and mixtures thereof, and more preferably, the elastomer is selected from ethylene-1-octene copolymer. Most preferably, the elastomer is ethylene-1-octene copolymer.

[0099] Preferably, the density of the polyolefin-based elastomer is in the range of 0.845 to 0.883 g / cm 3 preferably in the range of 0.848 to 0.865 g / cm 3 more preferably in the range of 0.853 to 0.860 g / cm 3within the range as measured according to ASTM D792-13.

[0100] Preferably, the MFI of the polyolefin-based elastomer is in the range of 0.5 to 18.0, preferably in the range of 0.8 to 14.2 dg / min, as measured according to ASTM D1238-13, at 190 °C, 2.16 kg.

[0101] The Shore A hardness of the polyolefin-based elastomer is preferably in the range of 35 to 90, preferably in the range of 42 to 69, more preferably in the range of 47 to 60, as measured according to ASTM D2240-15, 1 s.

[0102] The inventors have surprisingly found that the thermoplastic composition according to the invention has excellent drop weight impact resistance at -40 °C, said thermoplastic composition comprising a polyolefin-based elastomer having an MFI in the range of 0.8 to 14.2 dg / min as measured according to ASTM D1238-13, at 190 °C, 2.16 kg and a density in the range of 0.853 to 0.860 g / cm 3 as measured according to ASTM D792-13.

[0103] Suitable polyolefin-based elastomers for use in the present invention are commercially available, for example, under the trademark EXACT TM from Exxon Chemical Company, Houston, Texas, or under the trademark ENGAGE TM polymers (a series of metallocene-catalyzed elastomers) from Dow Chemical Company, Midland, Michigan, or under the trademark TAFMER TM from MITSUI Chemicals Group, Minato-ku, Tokyo, or under the trademark Fortify TM and Cohere TM from SABIC.

[0104] The polyolefin-based elastomer can be prepared using methods known in the art, for example, by using single-site catalysts, i.e., catalysts whose transition metal component is an organometallic compound and at least one of whose ligands has a cyclopentadienyl anion structure, through which such ligand is bonded and coordinated to the transition metal cation. This type of catalyst is also referred to as a "metallocene" catalyst. Metallocene catalysts are described, for example, in U.S. Patent Nos. 5,017,714 and 5,324,820. The elastomer can also be prepared using conventional types of multiphase multi-site Ziegler-Natta catalysts.

[0105] Preferably, the amount of ethylene incorporated in the polyolefin-based elastomer is at least 45% by weight. More preferably, the amount of ethylene incorporated in the polyolefin-based elastomer is at least 48% by weight, such as at least 50% by weight. The amount of ethylene incorporated in the polyolefin-based elastomer can typically be at most 95% by weight, such as at most 85% by weight, such as at most 75% by weight, such as at most 65% by weight, such as at most 60% by weight, such as at most 58% by weight.

[0106] The amount of the polyolefin-based elastomer is preferably in the range of 5 to 20% by weight, more preferably in the range of 7 to 15% by weight, based on the total amount of the thermoplastic composition.

[0107] Other additives

[0108] The thermoplastic composition of the present invention may additionally optionally contain 0 - 20% by mass of other additives. This includes conventional additives such as nucleating agents, clarifying agents, stabilizers, release agents, plasticizers, antioxidants, UV stabilizers such as HALS compounds, colorants, flame retardant additives, minerals, lubricants such as calcium stearate, mold release agents, flow enhancers, and / or antistatic agents. Those skilled in the art will know how to select the type and amount of additives when needed and apply them in amounts such that they do not have an adverse effect on the target properties of the composition.

[0109] In order to further enhance especially scratch resistance, scratch-resistant additives such as silicone can also be added, as known from other publications.

[0110] In an example of the composition of the present invention, it contains one or more of the following additives:

[0111] 0.05 to 5.0% of a nucleating agent, such as talc, metal stearates, etc.,

[0112] 0.10 to 0.8% of a mold release agent, such as fatty acid esters, for example PETS (pentaerythritol tetrastearate) or GMS (glycerol monostearate), fatty acid amides, for example EBS wax, polyolefins, etc.,

[0113] 0.1 to 1.0% of an antioxidant, such as hindered phenols, phosphorus-containing stabilizers, thioesters, lactones, or combinations thereof,

[0114] 0.1 to 5% of a colorant, such as carbon black and zinc sulfide, and in some cases less than 100 ppm of titanium dioxide, which may break the glass fibers, reduce the fiber length and impair the mechanical properties.

[0115] In some cases, the composition may additionally comprise a glass-resin coupling agent such as alkoxysilane, aminosilane, zirconate, titanate and maleic anhydride (MA) or glycidyl methacrylate (GMA) modified polyolefins such as PEgGMA, PPgMA to improve the GF resin adhesion.

[0116] Production of thermoplastic composition

[0117] The composition according to the present invention can be prepared by known methods, for example, by mixing all components other than glass fibers on an extruder to obtain a composition in the form of pellets or granules. The composition can also be prepared by blending different pellets of different compositions. Preferably, the composition is a mixture of pellets of different compositions and a masterbatch (or concentrate) containing glass fibers, i.e., a composition based on a polymer matrix and 30-75% by mass of long glass fibers. The polymer matrix in the masterbatch is as described above for the polypropylene according to the present invention and can be the same or different from the polypropylene in other pellets. The advantage is that the LGF PP blend can be prepared in an effective manner and the total amount of glass fibers in the final composition and in additional molded articles can be easily adjusted to optimize the properties. Preferably, the masterbatch contains 35-70% by mass, 40-65% by mass or 45-60% by mass of glass fibers.

[0118] The molded article according to the present invention can be a semi-finished or finished product made from the polypropylene composition by a molding method. Examples of suitable molding methods include injection molding, compression molding, extrusion and co-extrusion compression molding. Injection molding is most widely used for producing articles such as automotive parts. The semi-finished product can then undergo additional known processing steps. The article according to the present invention preferably has a so-called textured surface, which additionally reduces the sensitivity and / or visibility to surface damage such as scratches.

[0119] Generally, the length of the glass fibers in the polymer composition decreases during a melt processing step such as injection molding. The average length of the glass fibers in the molded article made from the composition according to the present invention can vary over a wide range depending on both the starting length and the processing conditions. Preferably, the average fiber length in the molded article is at least 0.5, 0.6, 0.7, 0.8 or 0.9 mm, and most preferably about 1 to 5 mm.

[0120] Foamed thermoplastic composition

[0121] In one aspect of the present invention, a foamed glass fiber reinforced thermoplastic composition is produced by foaming an unfoamed glass fiber reinforced thermoplastic composition via an injection foam process (FIM) or an extrusion foam process.

[0122] Among the various injection molding foaming processes known in the art, it is preferred to prepare the foamed glass fiber reinforced thermoplastic composition during the core-back injection molding process. The core-back injection molding process is preferred because such a process can result in a foamed product with a higher degree of density reduction. The core-back injection molding process can also be referred to as the open mold process.

[0123] A typical core-back injection molding process includes the following sequential steps:

[0124] · Provide a thermoplastic composition and a blowing agent to an injection molding machine;

[0125] · Inject the molten mixture of the thermoplastic composition and the blowing agent into a mold;

[0126] · At least partially open the mold to allow the mixture to form a soft-foamed thermoplastic composition, and;

[0127] · Cure the soft-foamed thermoplastic composition to form a foamed thermoplastic composition and discharge the foamed thermoplastic composition from the mold.

[0128] The blowing agent according to the present invention can be a physical blowing agent or a chemical blowing agent. A chemical blowing agent is a chemical substance that decomposes at a specific temperature to release a gas, while a physical blowing agent is a volatile liquid or gas.

[0129] Typical chemical blowing agents include, but are not limited to, azodicarbonamide, sodium bicarbonate, and citric acid derivatives.

[0130] Typical physical blowing agents include, but are not limited to, fluids in a gaseous or supercritical state such as nitrogen, carbon dioxide, hydrocarbons (such as butane, pentane), and mixtures thereof.

[0131] The amount of the blowing agent used in the present invention can be varied according to its nature and the foaming performance of the blowing agent. In some cases, the amount of the blowing agent varies in the range of 1-5% by weight, preferably in the range of 2-3% by weight, based on the total weight of the thermoplastic composition and the blowing agent.

[0132] In some cases, articles are directly produced from the thermoplastic composition by the FIM process, especially the core-back injection molding process.

[0133] In some cases, integral articles are produced from the foamed thermoplastic composition produced by the FIM process.

[0134] In some cases, a laminated article is produced from a foamed thermoplastic composition. The laminated article may comprise two, three, four or five layers etc., at least one of which is produced from a foamed thermoplastic composition. In the case of a three-layer article comprising a core layer and two adjacent skin layers, the core layer is produced from a foamed thermoplastic composition, and at least one skin layer is produced from an unfoamed thermoplastic composition, which may be the same as or different from the thermoplastic composition before foaming.

[0135] Experimental examples

[0136] The foamed and unfoamed specimens were prepared via injection molding using an Arburg Allrounder 520H1500-800 unit, and the dielectric properties were measured and recorded as in Table 1 below.

[0137] A composition of 98 wt% STAMAX 30YM240 (commercially obtained from SABIC, a 30% long glass fiber reinforced grade thermoplastic composition according to the present invention) and 2 wt% Hydrocerol ITP818 chemical blowing agent masterbatch (commercially obtained from Avient) was prepared by dry blending in the form of a pellet mixture.

[0138] Subsequently, the pellet mixture was added to the hopper of an injection molding machine, and the injection molding machine was set to a barrel temperature of 250 °C and a mold temperature of 40 °C.

[0139] The pellet mixture was thermally melted and then the molten mixture was injected into a mold cavity with a (nominal) thickness of 1.5 mm; subsequently, the mold part was opened to an additional distance of 0.75 mm and 1.5 mm, obtaining foamed specimens with densities of 679 kg / m 3 (Example 1) and 518 kg / m 3 (Example 2).

[0140] A second set of samples was prepared using a mold cavity with a (nominal) thickness of 2.0 mm; subsequently, the mold part was opened to a distance of 1.0 mm, obtaining a foamed specimen with a thickness of 3.0 mm and a density of 661 kg / m 3 (Example 3).

[0141] In addition, unfoamed STAMAX 30YM240 specimens with thicknesses of 1.5 mm (Comparative Example 1) and 2.0 mm (Comparative Example 2) were prepared under the same conditions, except that the chemical blowing agent was not mixed with the STAMAX pellets and the mold cavity was not partially opened during the molding process.

[0142] The dielectric properties of Dk and Df values were measured for all example specimens at frequencies of 1.0 GHz and 1.9 GHz. For the purposes of this invention, unless otherwise stated, the Dk and Df values at a frequency of 1.0 GHz were measured by the parallel plate capacitance method (impedance analyzer), and the Dk and Df values at a frequency of 1.9 GHz were measured by the split post dielectric resonator (SPDR) method, both measured in accordance with the GB12636 method "Strip line test method for complex permittivity of microwave dielectric substrates". Before testing, specimens were prepared and pre-dried at a temperature of 120 °C for 90 minutes, and then cooled to room temperature in a drying container.

[0143] In addition, the density was measured according to ISO 1183-1:2004.

[0144] Table 1

[0145] Example number Comparative example 1 Example 1 Example 2 Comparative example 2 Example 3 Form Unfoamed Foamed Foamed Unfoamed Foamed Nominal thickness (mm) 1.5 2.25 3 2 3 Estimated foaming ratio * n.a. 33％ 50％ n.a. 33％ <![CDATA[Density (kg / m 3 )]]> 1145 679 518 1130 661 <![CDATA[Weight loss ** > n.a. 41％ 55％ n.a. 42％ Dk (1.0 GHz) (STC-K) 2.67 1.84 1.67 2.52 1.83 Df (1.0 GHz) (STC-K) / 0.0012 0.0013 / 0.0014 Dk (1.9 GHz) (STC-S) 2.67 2.00 1.76 2.71 1.98 Df (1.9 GHz) (STC-S) 0.0027 0.0027 0.0024 0.0026 0.0028

[0146] * Estimated foaming ratio = [1 - (thickness of foamed specimen) / (thickness of unfoamed specimen)] * 100%

[0147] ** Weight loss = [1 - (density of foamed specimen) / (density of unfoamed specimen)] * 100%

[0148] The dielectric properties of the foamed LGF PP appear to have been significantly improved, with lower Dk values and comparable Df values, and a significant increase in weight loss. Therefore, foamed LGF PP is suitable for new application fields such as 5G radomes or housing components, and is also more ergonomic for construction workers.

Claims

1. A foamed glass fiber-reinforced thermoplastic composition, comprising, based on its total weight: (a) 30 - 90% by weight of a thermoplastic polymer matrix, (b) 10 - 70% by weight of glass fibers, and (c) 0.5 - 20% by weight of an impregnating agent, wherein the density reduction rate of the foamed glass fiber-reinforced thermoplastic composition is at least 30%, and wherein the density reduction rate is calculated according to (d 未发泡 -d 发泡 ) / d 未发泡 , where d 发泡 is the density of the foamed glass fiber-reinforced thermoplastic composition, and d 未发泡 is the density of the same unfoamed glass fiber-reinforced thermoplastic composition.

2. The foamed glass fiber-reinforced thermoplastic composition according to claim 1, wherein the density reduction rate is at least 35%, preferably at least 40%, more preferably at least 45%.

3. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the density reduction rate is at most 70%, preferably at most 65%, more preferably at most 60%.

4. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the Dk value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.0 GHz according to GB12636 is at most 1.90, preferably at most 1.80, and / or the Df value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.0 GHz according to GB12636 is at most 0.0015, preferably at most 0.0014.

5. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the Dk value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.9 GHz according to GB12636 is at most 2.10, preferably at most 2.00, and / or the Df value of the foamed glass fiber-reinforced thermoplastic composition tested at a frequency of 1.9 GHz according to GB12636 is at most 0.0030, preferably at most 0.0028.

6. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the foamed glass fiber-reinforced thermoplastic composition is produced by foaming an unfoamed glass fiber-reinforced thermoplastic composition via an injection molding foaming process or an extrusion foaming process.

7. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the glass fiber-reinforced thermoplastic composition is in the form of pellets, which comprise a core extending axially and a thermoplastic polymer sheath tightly surrounding the core, wherein the core comprises a plurality of long glass fiber filaments and the impregnating agent, and the sheath is substantially free of the filaments.

8. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, which further comprises (d) 5 - 20% by weight of at least one polyolefin-based elastomer.

9. The foamed glass fiber-reinforced thermoplastic composition according to any one of the preceding claims, wherein the thermoplastic polymer matrix comprises at least one polypropylene polymer, which is preferably a polypropylene homopolymer.

10. The foamed glass fiber-reinforced thermoplastic composition according to claim 7, wherein the impregnating agent is polyethylene wax.

11. The foamed glass fiber-reinforced thermoplastic composition according to claim 8, wherein the polyolefin-based elastomer is an ethylene-1-octene copolymer.

12. A method for producing a foamed glass fiber reinforced thermoplastic composition, comprising the following sequential steps: i. Providing a thermoplastic composition and a blowing agent, wherein the thermoplastic composition comprises, based on its total weight: (a) 30 - 90 wt% of a thermoplastic polymer matrix, (b) 10 - 70 wt% of glass fibers, and (c) 0.5 - 20 wt% of an impregnating agent; and ii. Foaming the thermoplastic composition such that the density reduction rate of the foamed glass fiber-reinforced thermoplastic composition is at least 30%, where the density reduction rate is calculated as (d 未发泡 - d 发泡 ) / d 未发泡 , where d 发泡 is the density of the foamed glass fiber-reinforced thermoplastic composition, and d 未发泡 is the density of the unfoamed same glass fiber-reinforced thermoplastic composition.

13. An article produced from the foamed glass fiber reinforced thermoplastic composition according to any one of the preceding claims 1 - 11 or from a foamed glass fiber reinforced thermoplastic composition produced by the method according to claim 12.

14. An article comprising a core layer and two adjacent surface layers, wherein the core layer is produced from the foamed glass fiber reinforced thermoplastic composition according to any one of the preceding claims 1 - 11 or from a foamed glass fiber reinforced thermoplastic composition produced by the method according to claim 12, and at least one of the surface layers is produced from an unfoamed thermoplastic composition.

15. The article according to any one of the preceding claims 13 - 14, wherein the article is an antenna housing or a radome.