Method for producing intrinsically foamed polyamide and shaped article therefrom

Abstract

To provide: a method for producing an intrinsically foamed polyamide which has acceptable density reduction, is processable due to acceptable melt strength, has high void fraction without significant bubble collapsing, and is appropriate and advantageous for application in automotive parts, insulation material, structural reinforcing components, furniture components, window thermal breaker strips, tubes, pipes, cable jackets, and electronic and electrical parts; and the polyamide and a shaped article.SOLUTION: A method for producing an intrinsically foamed polyamide comprises the steps of: melt-compounding a compounding mixture comprising a polyamide with a viscosity number from 90 ml / g to 350 ml / g, a copolymer having a weight average molecular weight from 5000 g / mol to 15000 g / mol, and a reinforcing agent; and extruding or molding the compounding mixture to obtain the intrinsically foamed polyamide.SELECTED DRAWING: None

Description

[Technical field]

[0001] detail The presently claimed invention relates to a method for producing an essentially expanded polyamide, and to shaped articles comprising an essentially expanded polyamide. [Background technology]

[0002] The reduced density of the polymer is advantageous in a variety of applications, such as, but not limited to, transportation and insulation applications.

[0003] Foaming is one such technique, where the density of the resulting polymer foam can be controlled. Typically, foaming involves the use of blowing agents, such as physical and chemical blowing agents. Physical blowing agents are inert volatile compounds, such as, but not limited to, hydrofluorocarbons, hydrochlorofluorocarbons, and hydrofluoroolefins. These are added to the polymer to foam in the melt and expand as a result of the high temperature, thereby resulting in a polymer foam with the desired density.

[0004] Chemical blowing agents are compounds that undergo a chemical reaction in the melt and, in the process, release a propellant, which expands and foams the polymer melt to a desired density. Blowing agents are widely used to produce foams, but are less effective when high levels of porosity are desired.

[0005] Polymers such as polyamides are widely used in a variety of applications including transportation and insulation. As one of the most important engineering plastics, polyamides are known for their high temperature performance, stiffness, chemical resistance, fatigue performance, and other mechanical properties.

[0006] However, melt foaming of polyamides is very difficult and can be performed in a very narrow process window, mainly due to their inherent low melt strength. This becomes even more difficult when a foamed material with high expansion ratio and high porosity is desired. High melt strength is important for processing highly expanded foams.

[0007] Polyamide foams are described in U.S. Publication No. 2014 / 0323631 (A1), U.S. Patent No. 7,671,127 (B2), and U.S. Patent No. 6,211,266 (B1), which describe the use of copolymers, particularly styrene maleic anhydride copolymers, as suitable chain extenders in combination with polyamides and their copolymers.

[0008] Existing polyamide foams describe the use of styrene maleic anhydride, but there are several limitations. One such limitation is adequately reducing foam density without affecting mechanical properties. Moreover, existing compositions do not provide processable melt strength to the composition, resulting in very low porosity of the resulting foam, which makes them unsuitable for applications in automotive parts, insulation materials, structural reinforcement components, furniture components, window heat breaker strips, tubes, pipes, cable jackets, electronic and electrical components.

[0009] It is therefore an object of the present claimed invention to provide a process for producing essentially foamed polyamides that have acceptable density reduction, are processable due to acceptable melt strength, have high porosity without significant bubble collapse, making them suitable and advantageous for applications in automotive parts, insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubing, pipes, cable jacketing, electronic and electrical components.

[0010] Summary of the Invention Surprisingly, the above objectives have been met by providing a method for producing an essentially foamed polyamide comprising the steps of: (A) melt blending a blended mixture comprising a polyamide having a viscosity number determined according to ISO 307 of 90 ml / g to 350 ml / g, a copolymer having a weight average molecular weight of 5000 g / mole to 15000 g / mole, and a reinforcing agent; and (B) extruding or molding said blended mixture to obtain an essentially foamed polyamide.

[0011] Thus, in one aspect, the presently claimed invention provides a method for producing an essentially foamed polyamide, comprising the steps of: (A) (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) melt blending a blended mixture containing a reinforcing agent; (B) Porosity between 1% and 60% as determined from scanning electron microscopy, and 1500 kg / m as determined according to ISO 1183 / A. 3 and extruding or molding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density of less than 100%.

[0012] In another aspect, the claimed invention relates to the essentially foamed polyamide obtained above.

[0013] In yet another aspect, the presently claimed invention relates to a molded article comprising the inherently expanded polyamide described above. [Brief description of the drawings]

[0014] [Figure 1] 1 shows a scanning electron microscope image of an intrinsically foamed polyamide. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Before describing the present compositions and formulations of the present invention, it is to be understood that the invention is not limited to the particular compositions and formulations described, as such compositions and formulations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the invention as claimed will be limited only by the appended claims.

[0016] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," or "containing," "contains," and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps. As used herein, the terms "comprising," "comprises," and "comprised of" will be understood to include the terms "consisting of," "consists," and "(consists of).

[0017] Furthermore, terms such as "first", "second", "third", or "a", "b", "c", "d" and the like in the description and claims are used to distinguish between similar elements and do not necessarily describe a sequential or chronological order. It is understood that terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein can be performed in other orders than those described or illustrated herein. When terms such as "first", "second", "third", or "(A)", "(B)" and "(C)", or "(a)", "(b)", "(c)", "(d)", "i", "ii", etc., relate to steps of a method or use or assay, unless otherwise indicated in the application described herein above or below, there is no consistency of time or time interval between the steps, i.e., the steps may be performed simultaneously or there may be a time interval of seconds, minutes, hours, days, weeks, months or years between such steps.

[0018] In the following passages, various aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects, unless expressly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0019] References throughout this specification to "an embodiment" or "one embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the claimed invention. Thus, the appearances of the phrase "an embodiment" or "one embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may. Furthermore, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure. Furthermore, some embodiments described herein include some features but not other features included in other embodiments, and combinations of features of different embodiments are meant to form different embodiments within the scope of the invention, as would be understood by one of ordinary skill in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0020] Furthermore, ranges defined throughout the specification are inclusive, i.e., a range of 1 to 10 means that both 1 and 10 are included in the range. For the avoidance of doubt, Applicant reserves the right to any equivalents pursuant to applicable law.

[0021] One aspect of the present claimed invention is a method for producing an essentially foamed polyamide, comprising the steps of: (A) (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) melt blending a blended mixture containing a reinforcing agent; (B) Porosity between 1% and 60% as determined from scanning electron microscopy (SEM) and 1500 kg / m as determined according to ISO 1183 / A 3and extruding or molding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density of less than 100%.

[0022] In one embodiment, the melt blending in step (A) described herein includes mixing and / or blending the blended mixture. Suitable mixing and blending means are well known to those skilled in the art. In addition, each component in the blended mixture can be added in any manner and order known to those skilled in the art.

[0023] Suitable conditions for melt blending are known to those skilled in the art, but in one embodiment, a temperature of 220° C. to 300° C. is maintained in step (A). In another embodiment, the temperature is 230° C. to 280° C., or 240° C. to 260° C.

[0024] In one embodiment, the viscosity number of the polyamides described herein is from 90 ml / g to 340 ml / g, or from 100 ml / g to 340 ml / g, or from 100 ml / g to 330 ml / g, or from 100 ml / g to 320 ml / g, or from 100 ml / g to 310 ml / g, or from 100 ml / g to 300 ml / g. In other embodiments, it is between 110 ml / g and 300 ml / g, or between 110 ml / g and 290 ml / g, or between 110 ml / g and 280 ml / g, or between 110 ml / g and 280 ml / g, or between 110 ml / g and 270 ml / g, or between 120 ml / g and 270 ml / g, or between 120 ml / g and 260 ml / g, or between 120 ml / g and 250 ml / g, or between 120 ml / g and 240 ml / g, or between 120 ml / g and 230 ml / g, or between 120 ml / g and 220 ml / g. In yet another embodiment it is between 130ml / g and 220ml / g, between 130ml / g and 210ml / g, or between 130ml / g and 200ml / g, between 130ml / g and 190ml / g, or between 140ml / g and 190ml / g, or between 140ml / g and 180ml / g, or between 140ml / g and 170ml / g, or between 140ml / g and 160ml / g.

[0025] In another embodiment, suitable polyamides are derived from lactams having, for example, 7 to 13 ring members or obtained by the reaction of dicarboxylic acids with diamines. Examples of polyamides derived from lactams include polycaprolactam, polycaprylolactam, and / or polylaurolactam.

[0026] In other embodiments, suitable polyamides further include those derived from ω-aminoalkylnitriles, such as, but not limited to, aminocapronitrile, which results in nylon-6. Additionally, dinitriles can be reacted with diamines. For example, adiponitrile can be reacted with hexamethylenediamine to give nylon-6,6. The polymerization of nitriles is carried out in the presence of water and is also known as direct polymerization.

[0027] When polyamides obtained from dicarboxylic acids and diamines are used, dicarboxylic alkanes (aliphatic dicarboxylic acids) having 6 to 36 carbon atoms, or 6 to 12 carbon atoms, or 6 to 10 carbon atoms, can be used. Aromatic dicarboxylic acids are also suitable. Examples of dicarboxylic acids include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and also terephthalic acid and / or isophthalic acid.

[0028] Suitable diamines include, for example, alkane diamines having 4 to 36 carbon atoms, or 6 to 12 carbon atoms, especially 6 to 8 carbon atoms, and aromatic diamines such as m-xylylenediamine, di(4-aminophenyl)methane, di(4-aminocyclohexyl)methane, 2,2-di(4-aminophenyl)propane, 2,2-di(4-aminocyclohexyl)propane, and 1,5-diamino-2-methylpentane.

[0029] In other embodiments, polyamides include polyhexamethylene dipamide, polyhexamethylene sebacamide, and polycaprolactam, and especially nylon-6 / 6,6 having a proportion of caprolactam units of 5% to 95% by weight.

[0030] In another embodiment, suitable polyamides include aliphatic, semi-aromatic, or aromatic polyamides. The term "aliphatic polyamide" is understood to mean that the polyamide is formed exclusively from aliphatic monomers. Similarly, the term "semi-aromatic polyamide" is understood to mean that the polyamide is formed exclusively from both aliphatic and aromatic monomers. Similarly, the term "aromatic polyamide" is understood to mean that the polyamide is formed exclusively from aromatic monomers.

[0031] The following non-exhaustive list includes the polyamides described above that are suitable for use in the compounded mixture of step (A).

[0032] AB Polymer: [Table 1] AA / BB polymer: [Table 2]

[0033] In one embodiment, the polyamide comprises an aliphatic polyamide. In another embodiment, the suitable polyamides described herein are selected from polyamide 6 (PA6), polyamide 66 (PA66), or blends or copolymers thereof.

[0034] Thus, in another embodiment, the blended mixture in step (A) comprises: (a) a polyamide selected from PA6, PA66, or blends or copolymers thereof; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent.

[0035] In yet another embodiment, the blended mixture in step (A) comprises: (a) a polyamide including PA6; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent.

[0036] A suitable amount of polyamide described herein is 10% to 95% by weight based on the total weight of the compounded mixture. In one embodiment, the amount of polyamide is 15% to 95% by weight, or 15% to 90% by weight. In another embodiment, the amount is 20% to 90% by weight, or 20% to 85% by weight. In yet another embodiment, it is 25% to 85% by weight, or 25% to 80% by weight. In yet another embodiment, it is 25% to 75% by weight, or 25% to 70% by weight, or 35% to 60% by weight.

[0037] In one embodiment, the copolymer in the blended mixture has a weight average molecular weight (Mw) of 6000 g / mol to 15000 g / mol, or 6000 g / mol to 14000 g / mol. In another embodiment, it is 6000 g / mol to 13000 g / mol, or 6000 g / mol to 12000 g / mol, or 6000 g / mol to 11000 g / mol. In yet other embodiments, it is 7000 g / mol to 11000 g / mol, or 8000 g / mol to 11000 g / mol, or 8000 g / mol to 10000 g / mol, or 9000 g / mol to 10000 g / mol. Suitable methods for determining Mw are known to those skilled in the art. For example, gel permeation chromatography (GPC) can be used in this context.

[0038] The copolymers are obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer. Suitable processes for the copolymerization reaction between (b1) and (b2) are known to those skilled in the art. For example, see BV Traildi and BM Culbertson, Plenum Press 1982, 1 st Reference may be made to Chapters 9 and 10 of the Maleic Anhydride by the US Pat. No. 6,399,341, issued in 1997.

[0039] In one embodiment, suitable vinyl monomers are selected from vinyl aromatic monomers, vinyl aliphatic monomers, acrylates, or mixtures thereof. In other embodiments, the vinyl monomers include styrene, alpha-methylstyrene, para-methylstyrene, or mixtures thereof. The vinyl aliphatic monomers include ethylene, propylene, or mixtures thereof. The acrylates include acrylates, methacrylates, or mixtures thereof. In other embodiments, the vinyl monomer is styrene.

[0040] In particular, copolymers containing styrene maleic anhydride (SMA) are advantageous for the present invention because they function as chain extenders as well as blowing agents. SMA is thermally stable and non-volatile, and generates CO2 when subjected to fabrication techniques in step (B) via decarboxylation. It also inherently improves melt viscosity and strength, which are necessary to form a stable cell structure in the foamed polyamide. Thus, minimal or no cell collapse is observed in the cell structure.

[0041] In another embodiment, the copolymer described herein is obtained by reacting a mixture comprising (b1) maleic anhydride and (b2) styrene. Thus, the blended mixture in step (A) comprises: (a) a polyamide selected from PA6, PA66, or blends or copolymers thereof; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic anhydride and (b2) styrene; (c) a reinforcing agent.

[0042] In another embodiment, the blended mixture in step (A) comprises: (a) a polyamide including PA6; (b) a copolymer having a weight average molecular weight of 7000 g / mol to 11000 g / mol, the copolymer being obtained by reacting a mixture comprising (b1) maleic anhydride and (b2) styrene; (c) a reinforcing agent.

[0043] In another embodiment, the copolymer described herein is obtained by reacting a mixture comprising (b1) and (b2) in a molar ratio of 1:1 to 5:1. In one embodiment, the molar ratio is 1.5:1 to 5:1, or 1.5:1 to 4.5:1, or 1.5:1 to 4:1. In another embodiment, the molar ratio is 2:1 to 4:1, or 2.5:1 to 4:1. In yet another embodiment, the molar ratio is 2.5:1 to 3.5:1.

[0044] Thus, in one embodiment, the blended mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent, Here, the molar ratio between (b1) and (b2) is 1:1 to 5:1.

[0045] In another embodiment, the blended mixture in step (A) comprises: (a) a polyamide selected from PA6, PA66, or blends or copolymers thereof; (b) a copolymer having a weight average molecular weight of 7000 g / mol to 11000 g / mol, the copolymer being obtained by reacting a mixture comprising (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent, Here, the molar ratio between (b1) and (b2) is 1:1 to 5:1.

[0046] In another embodiment, the blended mixture in step (A) comprises: (a) a polyamide including PA6; (b) a copolymer having a weight average molecular weight of 7000 g / mol to 11000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic anhydride and (b2) styrene; (c) a reinforcing agent, Here, the molar ratio between (b1) and (b2) is 1:1 to 5:1.

[0047] The preferred amount of copolymer in the compounded mixture in step (A) described herein is 0.05% to 10.0% by weight based on the total weight of the compounded mixture. In one embodiment, the amount of polyamide is 0.05% to 9.0% by weight, or 0.1% to 9.0% by weight, or 0.1% to 8.0% by weight, or 0.2% to 8.0% by weight, or 0.2% to 7.0% by weight, or 0.3% to 7.0% by weight, or 0.3% to 6.0% by weight. In another embodiment, the amount is somewhere in between. In yet another embodiment, it is 0.4% to 6.0% by weight, or 0.4% to 5.0% by weight, or 0.5% to 5.0% by weight, or 0.5% to 4.0% by weight, or 0.6% to 4.0% by weight. In yet another embodiment, it is between 0.7% and 4.0% by weight, or between 0.8% and 4.0% by weight, or between 0.9% and 4.0% by weight.

[0048] In another embodiment, suitable reinforcing materials include woven and non-woven fabrics selected from metal fibers, metallized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulose fibers, sisal fibers, and coir fibers.

[0049] In one embodiment, the reinforcing agent is selected from metal fibers, metallized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, kenaf fibers, jute fibers, flax fibers, and hemp fibers. In another embodiment, it is selected from metal fibers, metallized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, and mineral fibers. In yet another embodiment, it is selected from metal fibers, metallized synthetic fibers, and glass fibers. In yet another embodiment, the reinforcing agent is glass fibers.

[0050] Thus, in one embodiment, the blended mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) glass fiber.

[0051] In another embodiment, the reinforcing agents described herein are subjected to a surface treatment, also known as a sizing. The reinforcing agents further improve their mechanical properties when subjected to a surface treatment.

[0052] In one embodiment, the surface treatment agent is a coupling agent comprising one or more of a silane coupling agent, a titanium coupling agent, an aluminate coupling agent, a urethane coupling agent, and an epoxy coupling agent. In another embodiment, the coupling agent comprises a urethane coupling agent or an epoxy coupling agent. Suitable techniques for surface treatment are known to those skilled in the art. Any suitable coating process may be used, such as, but not limited to, dip coating and spray coating.

[0053] In one embodiment, the urethane coupling agent comprises at least one urethane group. Suitable urethane coupling agents for use with polyamides are known to those skilled in the art and are described, for example, in US Publication No. 2018 / 0282496, which is incorporated herein by reference. In one embodiment, the urethane coupling agent comprises the reaction product of an isocyanate, such as, but not limited to, m-xylylene diisocyanate (XDI), 4,4'-methylenebis(cyclohexylisocyanate) (HMDI) or isophorone diisocyanate (IPDI), and a polyester-based polyol, or a polyether-based polyol.

[0054] In another embodiment, the epoxy coupling agent comprises at least one epoxy group. Epoxy coupling agents suitable for use with polyamides are known to those skilled in the art and are described, for example, in US Publication No. 2015 / 0247025, which is incorporated herein by reference. In one embodiment, the epoxy coupling agent is selected from an aliphatic epoxy coupling agent, an aromatic epoxy coupling agent, or a mixture thereof. Non-limiting examples of aliphatic coupling agents include polyether polyepoxy compounds having two or more epoxy groups in the molecule, and / or polyol polyepoxy compounds having two or more epoxy groups in the molecule. As aromatic coupling agents, bisphenol A epoxy compounds or bisphenol F epoxy compounds may be used.

[0055] Suitable amounts of the surface treatment agents described herein are well known to those skilled in the art. Furthermore, the amounts of these surface treatment agents described herein vary depending on the application of the reinforcing agent. However, in one embodiment, the surface treatment agent may be present in an amount of 0.1 parts by weight to 10.0 parts by weight based on 100 parts by weight of the reinforcing agent.

[0056] For purposes of the present invention, the reinforcing agent can be of any shape and size. For example, the reinforcing agent can be, but is not limited to, a strand having transverse and in-plane dimensions, or a spherical particle having a diameter. The present invention is not limited by the shape and size of the reinforcing agent. For example, the reinforcing agent can have an average dimension of 1 μm to 20 μm as determined according to ASTM D578-98.

[0057] Further, the suitable amount of reinforcing material described herein is 5% to 70% by weight based on the total weight of the compounded mixture. In one embodiment, it is 10% to 70% by weight, or 10% to 65% by weight, or 15% to 65% by weight. In another embodiment, it is 15% to 60% by weight, or 20% to 60% by weight, or 20% to 60% by weight. In yet another embodiment, it is 25% to 60% by weight, or 30% to 60% by weight.

[0058] The compounded mixture in step (A) further comprises an impact modifier and / or a nucleating agent. Thus, in one embodiment, the compounded mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent; and (d) impact modifier.

[0059] In another embodiment, the blended mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent; and (d) a nucleating agent.

[0060] In yet another embodiment, the blended mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent; and (d) an impact modifier; and (e) a nucleating agent.

[0061] Impact modifiers, often also referred to as rubber or elastomeric polymers, for use in the present invention are described, for example, in U.S. Publication Nos. 2014 / 0323631 (A1) and 2008 / 0070023 (A1), all of which are incorporated herein by reference. Suitable impact modifiers are selected from (i) ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, and (ii) olefin or acrylic acid or anhydride terpolymers and ionomers.

[0062] In the ethylene polymers and copolymers grafted with carboxylic acids, their anhydrides, maleimides, or epoxy compounds, the carboxylic acids or their anhydrides are selected from maleic acid, fumaric acid, itaconic acid, acrylic acid, crotonic acid, C1-C4 alkyl half esters of maleic acid, and their anhydrides or derivatives, including maleic anhydride. Olefinic rubbers may also be used as suitable impact modifiers.

[0063] In one embodiment, the impact modifier is an ethylene copolymer grafted with a carboxylic acid or any anhydride thereof, such as an ethylene copolymer grafted with maleic anhydride. In other embodiments, the impact modifier includes maleic anhydride grafted ethylene propylene diene terpolymer (EPDM) (2% to 6% by weight maleic anhydride), maleic anhydride grafted ethylene propylene (0.5% to 6% by weight maleic anhydride), maleic anhydride grafted low density polyethylene (0.2% to 6% by weight maleic anhydride), and maleic anhydride grafted ethylene butyl acrylate (0.2% to 6% by weight maleic anhydride).

[0064] The olefin or acrylic acid or anhydride terpolymer and ionomeric impact modifier are polymerized with linear units derived from monomers including: (a) ethylene, butylene, propylene, and combinations thereof; (b) 2% to 25% by weight of an acid selected from acrylic acid, methacrylic acid, and mixtures thereof; and (c) 0.1% to 15% by weight of a dicarboxylic acid monomer selected from maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, C1-C4 alkyl half esters of maleic acid, and mixtures of these dicarboxylic acid monomers. In one embodiment, the terpolymer is an ethylene / methacrylic acid / maleic anhydride ionomer (0.5% to 12% by weight of maleic anhydride). The ionomers may be formed by neutralizing the carboxylic acid units in the terpolymer with metal ions selected from zinc, magnesium, manganese, and mixtures thereof, either alone or in combination with sodium or lithium ions. The terpolymer may further comprise up to 40% by weight of C1-C8 alkyl acrylate monomer units.

[0065] The impact modifiers described herein may be present in an amount of from 10% to 50% by weight based on the total weight of the compounded mixture.

[0066] Nucleating agents are known to those skilled in the art, but in one embodiment, a suitable nucleating agent is selected from sodium phenylphosphinate, aluminum oxide, silicon dioxide, talc powder, and mixtures thereof, hi another embodiment, the nucleating agent is talc powder.

[0067] In one embodiment, the nucleating agent may be present in an amount of 0.1% to 10.0% by weight based on the total weight of the blended mixture. In another embodiment, the amount is 0.1% to 9.0% by weight, or 0.1% to 8.0% by weight. In yet another embodiment, it is 0.5% to 8.0% by weight, or 0.5% to 7.0% by weight. In yet another embodiment, it is 0.75% to 7.0% by weight, or 0.75% to 6.5% by weight.

[0068] In another embodiment, the compounded mixture in step (A) further comprises an additive. Suitable additives are selected from stabilizers, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungistatic agents, bacteriostatic agents, IR absorbing materials, and antioxidants. These additives are known and can be found, inter alia, in, for example, Plastics Additives Handbook, Hanser, 4 th edition. Moreover, these additives may be used in any suitable amount for the present invention. In one embodiment, the additives are present in an amount of 0.1% to 20% by weight based on the total weight of the blended mixture.

[0069] Thus, in one embodiment, the blended mixture in step (A) comprises: (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) a reinforcing agent; and (d) an impact modifier; and (e) a nucleating agent; and (f) additives.

[0070] The compounded mixture obtained in step (A) is extruded or molded in step (B) to obtain the essentially foamed polyamide described herein.

[0071] In one embodiment, the compounded mixture is extruded to obtain an essentially foamed polyamide. Thus, the method for producing an essentially foamed polyamide comprises: (A) melt blending a blended mixture described herein; (B) Porosity between 1% and 60% as determined from SEM, and 1500 kg / m as determined according to ISO 1183 / A 3and extruding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density less than 100%.

[0072] In this context, extrusion refers to extrusion techniques known to those skilled in the art. Extrusion of the compounded mixture essentially results in foamed polyamide extrudates, which can be further cooled and ground. These extrudates can be of any suitable shape, size, and dimensions. Suitable temperatures for extrusion typically range from 220°C to 320°C. In one embodiment, the temperature is from 230°C to 280°C, or from 240°C to 260°C.

[0073] In other embodiments, suitable extruders include, but are not limited to, single screw extruders or twin screw extruders, etc. The extrudate obtained from these extruders can be in the form of, for example, a continuous strip or granules.

[0074] In another embodiment, the compounded mixture is molded to obtain an essentially foamed polyamide. Thus, the method for producing an essentially foamed polyamide comprises: (A) melt blending a blended mixture described herein; (B) Porosity between 1% and 60% as determined from SEM, and 1500 kg / m as determined according to ISO 1183 / A 3 and molding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density of less than 100000000.

[0075] In one embodiment, the molding in step (B) is selected from blow molding, compression molding, and injection molding. The temperature suitable for molding is typically in the range of 220°C to 320°C. In one embodiment, the temperature is 230°C to 280°C, or 240°C to 260°C.

[0076] Although the present invention describes steps (A) and (B) herein, depending on the application, there may be additional process steps required to obtain an essentially foamed polyamide. Additional process steps are known to the skilled person and therefore do not limit the present invention.

[0077] Furthermore, the method described herein provides acceptable melt strength, which allows the compounded mixture to be processed and essentially foamed polyamide is obtained. The essentially foamed polyamide obtained in step (B) is stable and does not show any bubble collapse due to the increase in melt strength. Furthermore, as seen in Figure 1, no bubble formation occurs on the surface of the essentially foamed polyamide. In fact, voids and bubbles are observed in the core of the material, not on the surface.

[0078] Moreover, the high porosity of inherently foamed polyamides with acceptable mechanical properties makes them useful in applications such as, but not limited to, automotive parts, insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubing, pipes, cable jacketing, electronic and electrical components.

[0079] In the present context, high porosity refers to a porosity of as much as 60% for essentially expanded polyamides. In one embodiment, the porosity is between 1% and 60% as determined from SEM. Further advantageous properties of the essentially expanded polyamides described herein include a porosity of 1500 kg / m2 as determined according to ISO 1183 / A. 3 These include, but are not limited to, a foam density of less than 0.1 mm, an average cell size of 5 μm to 250 μm as determined from SEM, and a tensile strength of 30 MPa to 250 MPa as determined according to ISO 527.

[0080] In one embodiment, the porosity is 5% to 60%, or 5% to 50%. The foam density is 500 kg / m 3 ~1500kg / m 3 The average cell size is 10 μm to 150 μm, and the tensile strength is 50 MPa to 180 MPa.

[0081] Moreover, the increased porosity of the inherently expanded polyamide results in a decrease in thermal conductivity as well as dielectric constant, making the inherently expanded polyamide advantageous for applications such as, but not limited to, thermal breakers.

[0082] Another aspect of the present invention relates to the inherently foamed polyamides described above.

[0083] Yet another aspect of the present invention relates to a molded article comprising the essentially expanded polyamide described above, the molded article being selected from automotive parts, insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubes, pipes, cable jacketing, electronic and electrical components.

[0084] The present claimed invention is illustrated in more detail by the following embodiments and combinations of embodiments which can be taken from the corresponding dependency references and links. 1. A process for producing an essentially foamed polyamide, comprising: (A) (a) a polyamide; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) melt blending a blended mixture containing a reinforcing agent; (B) Porosity between 1% and 60% as determined from scanning electron microscopy, and 1500 kg / m as determined according to ISO 1183 / A. 3 and extruding or molding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density of less than 100%.

[0085] 2. The method of embodiment 1, wherein in step (A), the melt blending is carried out at a temperature of 220°C to 320°C.

[0086] 3. The method of embodiment 1 or 2, wherein the polyamide has a viscosity number, determined according to ISO 307, of 90 ml / g to 350 ml / g.

[0087] 4. The method of one or more of the preceding embodiments, wherein the polyamide comprises an aliphatic polyamide.

[0088] 5. The method according to one or more of the preceding embodiments, wherein the polyamide is selected from polyamide 6, polyamide 66, or blends or copolymers thereof.

[0089] 6. The method of one or more of the preceding embodiments, wherein the polyamide comprises polyamide 6.

[0090] 7. The method according to one or more of the preceding embodiments, wherein the amount of polyamide is from 10% to 90% by weight, based on the total weight of the compounded mixture.

[0091] 8. The method of one or more of the preceding embodiments, wherein the copolymer has a weight average molecular weight of from 7000 g / mol to 11000 g / mol.

[0092] 9. The method of one or more of the preceding embodiments, wherein (b2) the vinyl monomer is styrene.

[0093] 10. The method according to one or more of the preceding embodiments, wherein the copolymer is obtained by reacting (b1) with (b2) in a molar ratio of 1:1 to 5:1.

[0094] 11. The method of embodiment 10, wherein the molar ratio is from 2:1 to 4:1.

[0095] 12. The method according to one or more of the preceding embodiments, wherein the amount of copolymer is from 0.1% to 10.0% by weight, based on the total weight of the blended mixture.

[0096] 13. The method according to one or more of the preceding embodiments, wherein the reinforcing agent is selected from metal fibers, metallized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulose fibers, sisal fibers, and coir fibers.

[0097] 14. The method of one or more of the preceding embodiments, wherein the reinforcing agent is glass fiber.

[0098] 15. The method according to one or more of the preceding embodiments, wherein the reinforcing agent is subjected to a surface treatment agent.

[0099] 16. The method of embodiment 15, wherein the surface treatment agent is a coupling agent comprising one or more of a silane coupling agent, a titanium coupling agent, an aluminate coupling agent, a urethane coupling agent, and an epoxy coupling agent.

[0100] 17. The method according to one or more of the preceding embodiments, wherein the amount of the reinforcing agent is 20% by weight to 70% by weight, based on the total weight of the compounded mixture.

[0101] 18. The method of one or more of the preceding embodiments, wherein the compounded mixture further comprises an impact modifier and / or a nucleating agent.

[0102] 19. The method of embodiment 18, wherein the amount of impact modifier is 10% by weight to 50% by weight, based on the total weight of the compounded mixture.

[0103] 20. The method of embodiment 19, wherein the amount of nucleating agent is 0.1% by weight to 10.0% by weight, based on the total weight of the blended mixture.

[0104] 21. The method of one or more of the preceding embodiments, wherein the compounded mixture further comprises an additive.

[0105] 22. The method of embodiment 21, wherein the additives are selected from stabilizers, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungistatic agents, bacteriostatic agents, IR absorbing materials, and antioxidants.

[0106] 23. The method of embodiment 22, wherein the amount of the additive is 0.1% by weight to 20% by weight, based on the total weight of the blended mixture.

[0107] 24. The method according to one or more of the preceding embodiments, wherein in step (B), a temperature of 220°C to 320°C is maintained.

[0108] 25. The method according to one or more of the preceding embodiments, wherein the molding in step (B) is selected from blow molding, compression molding, and injection molding.

[0109] 26. The method according to one or more of the preceding embodiments, wherein the porosity is between 5% and 50% as determined from scanning electron microscopy.

[0110] 27. Foam density is 500 kg / m3 determined according to ISO 1183 / A. 3 ~1500kg / m 3 27. The method according to one or more of embodiments 1-26, wherein

[0111] 28. The method according to one or more of the preceding embodiments, wherein the essentially foamed polyamide has a cell size of 10 μm to 150 μm as determined from scanning electron microscopy.

[0112] 29. The method according to one or more of the preceding embodiments, wherein the essentially foamed polyamide exhibits a tensile strength, determined according to ISO 527, of 30 MPa to 250 MPa.

[0113] 30. An essentially foamed polyamide obtained by the process according to one or more of embodiments 1 to 29.

[0114] 31. A shaped article comprising an essentially expanded polyamide according to embodiment 30 or obtained from the process according to one or more of embodiments 1 to 29.

[0115] 32. The molded article of embodiment 31, wherein the molded article is selected from automotive parts, thermal insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubes, pipes, cable jacketing, electronic and electrical components.

[0116] 33. A process for producing an essentially foamed polyamide, comprising: (A) (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture containing (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) melt blending a blended mixture containing a reinforcing agent; (B) Porosity between 1% and 60% as determined from scanning electron microscopy, and 1500 kg / m as determined according to ISO 1183 / A. 3 and extruding or molding the compounded mixture of step (A) to obtain an essentially expanded polyamide having a foam density of less than 100%.

[0117] 34. The method of embodiment 33, wherein in step (A), the melt blending is carried out at a temperature of 220°C to 320°C.

[0118] 35. The method of embodiment 33 or 34, wherein the polyamide comprises nylon-6.

[0119] 36. The method according to one or more of embodiments 33 to 35, wherein (b2) the vinyl monomer is styrene.

[0120] 37. The method according to one or more of embodiments 33 to 36, wherein the copolymer is obtained by reacting (b1) with (b2) in a molar ratio of 1:1 to 5:1.

[0121] 38. The method according to one or more of embodiments 33 to 37, wherein the amount of copolymer is 0.1% by weight to 10.0% by weight, based on the total weight of the blended mixture.

[0122] 39. The method according to one or more of embodiments 33-38, wherein the reinforcing agent is selected from metal fibers, metallized synthetic fibers, glass fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulose fibers, sisal fibers, and coir fibers.

[0123] 40. The method of one or more of embodiments 33-39, wherein the reinforcing agent is glass fiber.

[0124] 41. The method of one or more of embodiments 33-40, wherein the compounded mixture further comprises an impact modifier and / or a nucleating agent.

[0125] 42. The method of one or more of embodiments 33-41, wherein the compounded mixture further comprises an additive.

[0126] 43. The method of embodiment 42, wherein the additives are selected from stabilizers, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungistatic agents, bacteriostatic agents, IR absorbing materials, and antioxidants.

[0127] 44. The method according to one or more of embodiments 33-43, wherein in step (B), a temperature of 220°C to 320°C is maintained.

[0128] 45. The method according to one or more of embodiments 33-44, wherein the molding in step (B) is selected from blow molding, compression molding, and injection molding.

[0129] 46. ​​An essentially foamed polyamide obtained by the process according to one or more of embodiments 33 to 45.

[0130] 47. A shaped article comprising an essentially expanded polyamide as described in embodiment 16 or obtained by the process as described in one or more of embodiments 33 to 46.

[0131] 48. The molded article of embodiment 47, wherein the molded article is selected from automotive parts, thermal insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubes, pipes, cable jacketing, electronic and electrical components. EXAMPLES

[0132] The presently claimed invention is illustrated by the following non-limiting examples. compound [Table 3]

[0133] Standard Way [Table 4]

[0134] The weight average molecular weight of the copolymer was determined using GPC, while the porosity and average cell size were determined using density measurements and SEM techniques. To analyze the samples using SEM, the electron beam flow direction was adjacent to the surface.

[0135] compounded mixture Details regarding the compounded mixtures according to the present invention are summarized in Table 1. All amounts are in weight percent.

[0136] [Table 5]

[0137] General synthesis of intrinsically foamed polyamides. The compounded mixtures in Table 1 were extruded into continuous strips using a Davis Standard Single Screw Extruder. The extrusion temperature was 240°C to 280°C, and the screw speed was 20 to 30 rpm. A slit die (30.5mmx4mm) was used, and the material started to foam immediately upon exiting the die. The foamed strip-shaped extrudate was then placed in a cooling bath for cooling and solidification. It was finally pulled dry and collected. Dumbbell-shaped test specimens were made from the extruded strips using a cutting tool to measure the tensile properties.

[0138] From Table 1, the addition of 1.0 wt% to 2.5 wt% SMA increases the density of the 35 wt% glass-filled PA6 composite to 1150 kg / m 3 (18% porosity) to 910kg / m 3 It is clear that the extrusion process reduces the void content to 35% (35% void content). It is also clear that the SMA generates gas during the extrusion process and acts as a blowing agent. At the same time, as a chain extender, the SMA also increases the melt strength so that the foam bubbles can grow in the polymer melt without collapsing.

[0139] Effect of reinforcement and copolymer content The effect of reinforcing agent and copolymer content on the intrinsically foamed polyamide is summarized in Table 2. All amounts are in weight percent.

[0140] [Table 6]

[0141] The compounded mixtures in Table 2 were extruded into continuous strips using a single screw extruder. Dumbbell shaped test specimens were made from the extruded strips using a cutting tool to measure tensile properties. The density of each sample was also measured. The average cell size of all samples was measured and reported using SEM microscopy.

[0142] As is evident from Table 2, increasing the SMA content leads to a decrease in the density of the samples (or an increase in the porosity). The reinforcement content does not show a significant change in the porosity at low concentrations of SMA (i.e., 1.0 wt%).

[0143] Furthermore, increasing the SMA content intrinsically reduces the modulus of the foamed polyamide. Increasing the amount of reinforcing agent results in higher modulus values. Furthermore, at low SMA concentrations (1.0 wt%), the density is reduced by approximately 10-12%, but the modulus is maintained, especially for the 40 wt% and 50 wt% glass filled samples (Table 2).

[0144] SEM images were taken from areas adjacent to the surface of the extrudate samples. As is evident from the images, there is no bubble formation at the surface. All voids and bubbles are observed within the core of the material and not at the surface.

Claims

1. 1. A process for producing an essentially foamed polyamide comprising the steps of: (A) (a) a polyamide having a viscosity number, determined in accordance with ISO 307, of from 90 ml / g to 350 ml / g; (b) a copolymer having a weight average molecular weight of 5000 g / mol to 15000 g / mol, the copolymer being obtained by reacting a mixture comprising (b1) maleic acid and / or maleic anhydride, and (b2) a vinyl monomer; (c) melt blending the blended mixture containing a reinforcing agent; (B) a porosity of 1% to 60% as determined from scanning electron microscopy, and 1500 kg / m as determined in accordance with ISO 1183 / A. ３ and extruding or molding said compounded mixture of step (A) to obtain said essentially expanded polyamide having a foam density less than 100%.

2. 10. The method of claim 1, wherein in step (A), the melt blending is carried out at a temperature of from 220°C to 320°C.

3. The method of claim 1 or 2, wherein the polyamide comprises nylon-6.

4. The method according to one or more of claims 1 to 3, wherein (b2) the vinyl monomer is styrene.

5. 5. The method according to one or more of the preceding claims, wherein said copolymer is obtained by reacting (b1) with (b2) in a molar ratio of from 1:1 to 5:

1.

6. The method according to one or more of the preceding claims, wherein the amount of said copolymer is from 0.1% to 10.0% by weight, based on the total weight of the compounded mixture.

7. 7. The method according to one or more of claims 1 to 6, wherein the reinforcing agents are selected from metal fibres, metallised synthetic fibres, glass fibres, carbon fibres, ceramic fibres, mineral fibres, basalt fibres, inorganic fibres, kenaf fibres, jute fibres, flax fibres, hemp fibres, cellulose fibres, sisal fibres and coir fibres.

8. The method according to one or more of the preceding claims, wherein the reinforcing agent is glass fibre.

9. The method according to one or more of the preceding claims, wherein the compounded mixture further comprises an impact modifier and / or a nucleating agent.

10. The method according to one or more of claims 1 to 9, wherein the compounded mixture further comprises an additive.

11. 11. The method of claim 10, wherein the additive is selected from stabilizers, dyes, pigments, flame retardants, lubricants, UV absorbers, antistatic agents, fungistatic agents, bacteriostatic agents, IR absorbing materials, and antioxidants.

12. 12. The method according to one or more of the preceding claims, wherein in step (B) a temperature of from 220°C to 320°C is maintained.

13. The method according to one or more of the preceding claims, wherein the molding in step (B) is selected from blow molding, compression molding, and injection molding.

14. An essentially expanded polyamide obtained from the process according to one or more of claims 1 to 13.

15. A shaped article comprising the essentially expanded polyamide of claim 16 or obtained from the process of one or more of claims 1 to 14.

16. 16. The molded article of claim 15, wherein the molded article is selected from automotive parts, thermal insulation materials, structural reinforcement components, furniture components, heat breaker strips for windows, tubes, pipes, cable jacketing, electronic and electrical components.

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