Molding compositions and foamed articles made therefrom

Abstract

To provide a foamed article formed by foam injection molding or foam extrusion of a composition.SOLUTION: The article is formed from a molding composition consisting essentially of: 100 phr of at least two different hydrogenated styrenic block copolymers (HSBC), a first HSBC and a second HSBC, having different molecular weights with a molecular weight ratio of at least 1.2:1 respectively and a weight ratio of ranging from 5:95 to 95:5 respectively; 10 to 55 phr of a polypropylene having a melt flow of at least 2 g / 10 min; and optionally up to 55 phr of a plasticizer, selected from hydrocarbon based oils, fatty acids, triglyceride oils, and mixtures thereof. The composition has a melt flow rate of 2 to 50 g / 10 min, a Shore A hardness of 60 to 90, a melt strength (F) of at least 0.010 N, and a melt strength (V) of at least 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to molding compositions, methods for preparing same and articles made therefrom. [Background technology]

[0002] Automotive interior parts generally have aesthetic characteristics of cushioning and soft touch. Polymer foam-containing molding compositions play an important role in the production of such automotive parts because of the steadily increasing demand for lightweight automotive designs. The "cushioning" characteristic can be imparted by compositions containing flexible polymer foams or elastomer pads of various thicknesses, along with "soft skin" materials, which are relatively hard materials. Such automotive parts can be manufactured with a core-back injection molding process, which produces multiple layers in the same process.

[0003] A need exists for improved molding compositions for producing articles, such as automotive interior parts, via a core-back injection molding process, that have a high degree of reduced density combined with properties such as ease of processing and desirable hardness. Summary of the Invention

[0004] Summary of the Invention In one aspect, the disclosure relates to a foamed article made from a composition consisting essentially of: 100 phr of at least two different hydrogenated styrenic block copolymers (HSBCs), a first HSBC and a second HSBC, each having different molecular weights with a molecular weight ratio of at least 1.2:1 and a weight ratio in the range of 5:95 to 95:5, respectively; 10 to 55 phr of polypropylene having a melt flow of at least 2 g / 10 min according to ASTM D1238-82 (230° C. / 5 kg); and, optionally, up to 55 phr of a plasticizer selected from hydrocarbon-based oils, fatty acids, triglyceride oils, and mixtures thereof. The composition has a melt flow rate of 2-50 g / 10 min (230° C., 2.16 kg, measured by ASTM D1238-04), a Shore A hardness of 60-90 (15 sec, 23° C.) measured according to ISO 868, a melt strength (F) of at least 0.010 N, and a melt strength (V) of at least 10. The foamed article is formed by foam injection molding or foam extrusion and has a density reduced by at least 10% relative to an article formed from the unfoamed composition. The foamed article has a non-foamed skin layer completely covering a foamed inner core. [Brief description of the drawings]

[0005] [Figure 1] 1 is an optical microscope image of a cross section of a foamed sample obtained from the formula of Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The following terms are used herein and have the following meanings: "phr" means parts per hundred parts styrene block copolymer (SBC).

[0007] "Molecular weight" refers to the styrene-equivalent molecular weight of a polymer block or block copolymer in g / mol. Molecular weight can be measured, for example, by gel permeation chromatography (GPC) using polystyrene calibration standards performed according to ASTM 5296-19. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The molecular weight of polymers measured using GPC and calibrated in this way is the styrene-equivalent molecular weight. The styrene-equivalent molecular weight may be converted to properly match the molecular weight if the styrene content of the polymer and the vinyl content of the diene portion are known. The detector may be a combination of an ultraviolet detector and a refractive index detector. Molecular weights expressed herein are measured at the peak of the GPC trace converted to true molecular weight and are referred to as "peak molecular weight", commonly denoted as Mp. If not converted to true molecular weight as above, the molecular weight refers to the styrene-equivalent peak molecular weight.

[0008] The "polystyrene content" or PSC of a block copolymer refers to the percent weight of polymerized styrene in the block copolymer, calculated by dividing the sum of the molecular weights of all polystyrene blocks by the total molecular weight of the block copolymer. PSC can be determined using any suitable methodology, such as proton nuclear magnetic resonance (NMR).

[0009] The "melt flow rate" or "MFR" of the components in the molding composition can be measured according to ISO 1133-1 at a temperature of 230° C. and a load of 2.16 kg. The melt flow rate can also be measured according to ASTM D1238-04 at a temperature of 230° C. and a load of 2.16 kg.

[0010] "Shore A hardness" is a measure of the indentation resistance of an elastomer or soft plastic material based on the depth of penetration of a conical indenter, and can be measured according to ISO-868.

[0011] "Melt strength" refers to the resistance of a polymer melt to stretching or the extensional viscosity of a polymer composition, which can be determined by a Goettfert Rheotens device in which a molten extrudate or fiber strand is pulled between two powered rollers as it exits the downward extrusion orifice. As the speed of the rollers is increased, tension is created in the strand and measured by the Rheotens device. The force required to stretch the extrudate and subsequently break it is defined as melt strength, with maximum take-off speed or melt strength (V) defined as a relative measure of the "stretch" of the melt and maximum force or melt strength (F) defined as a relative value of melt strength measured in Newtons (N). Melt strength is measured at 230°C unless otherwise indicated.

[0012] "A / B" refers to a polymer block having a controlled distribution of monoalkenyl arene units in a diene polymer block, for example, B / S refers to a polymer block having a controlled distribution of styrene in a butadiene block.

[0013] The present disclosure relates to a "foamed" article having a foam inner layer and a denser soft skin. The article is formed from a molding composition comprising at least two styrenic block copolymer components, a high melt flow polypropylene, and optional plasticizers and additives.

[0014] Styrene block copolymer (SBC) componentThe molding composition includes two or more hydrogenated styrene block copolymers (HSBCs) of different molecular weights. Various HSBCs suitable for use include, independently, but are not limited to, selectively hydrogenated styrene-diene block copolymers, selectively hydrogenated styrene-diene-styrene triblock copolymers, selectively hydrogenated styrene-diene diblock copolymers, selectively hydrogenated resins of styrene-diene-styrene triblock copolymers, selectively hydrogenated styrene-diene random copolymers, selectively hydrogenated styrene-diene random copolymers, selectively hydrogenated controlled distribution styrene-diene / styrene block copolymers, selectively hydrogenated controlled distribution styrene-diene / styrene-styrene block copolymers, and combinations thereof. The diene may be any conjugated diene, such as, for example, butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, chloroprene, and piperylene, or any combination thereof.

[0015] In an embodiment, the HSBC composition is a styrene diblock copolymer (SBC) comprising an A block and a B block, designated AB, prior to hydrogenation, a linear triblock copolymer of the formula ABA, in which each A block is of different or the same peak molecular weight or has the same or different monoalkenyl arene content, and / or a linear triblock copolymer of the formula (AB) n In such an embodiment, A is a monoalkenyl arene block, B is a conjugated diene block, n is an integer from 2 to 6, and X is a residue of a coupling agent. n When X is a multi-arm coupled block copolymer, n is in the range of 2-4.

[0016] In an embodiment, the SBC is a controlled distribution styrenic block copolymer, which may be a styrenic diblock copolymer of the formula AB, a linear triblock copolymer of the formula ABA, and / or a copolymer of the formula (AB) nX, where the types and values ​​of A, B, X and n are as previously described herein.

[0017] In one embodiment, the HSBC composition comprises a hydrogenated styrenic block copolymer (HSBC), which is one or more SBCs including, prior to hydrogenation, a styrenic diblock copolymer of formula AB, a linear triblock copolymer of formula ABA, and / or a styrenic diblock copolymer of formula (AB) n A is a multi-arm coupling block copolymer of A, B, X, and n, where the types and values ​​of A, B, X, and n are as described herein above. In one embodiment, the HSBC is a hydrogenated resin of a styrene-isoprene-styrene triblock copolymer, a hydrogenated resin of a styrene-butadiene-styrene triblock copolymer, or a resin in which a certain portion of the polymerized conjugated diene (e.g., butadiene) is selectively hydrogenated. In one embodiment, the HSBC comprises a B block in which the addition of hydrogen molecules occurs across more than 92 mol %; or more than 95 mol %; or more than 98 mol % of the carbon-carbon double bonds in the B block. In another embodiment, the HSBC is a partially saturated hydrogenated styrene block copolymer comprising a B block in which the addition of hydrogen molecules occurs across 20 mol % to more than 92 mol %; or more than 25 mol % to more than 85 mol %; or more than 30 mol % to more than 80 mol % of the carbon-carbon double bonds in the B block.

[0018] The monoalkenyl arene block (A block) comprises any of styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, or mixtures thereof. In embodiments, the monoalkenyl arene block comprises essentially pure monoalkenyl arene monomers. In some embodiments, styrene is the major component of the A block, with minor proportions (less than 10 wt%) of structurally related vinyl aromatic monomers, such as o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, or combinations thereof. In some embodiments, the peak molecular weight of each monoalkenyl arene block (e.g., A block) is in the range of 5,000 to 12,000 g / mol, 5,000 to 11,000 g / mol, or 5,000 to 10,500 g / mol.

[0019] In embodiments, the monoalkenyl arene content of each A block is 10% to 60% by weight; or 15% to 50% by weight, based on the total weight of the SBC. In one aspect where the SBC is of formula ABA, the combined monoalkenyl arene content of all A blocks is within the range of 10% to 60% by weight; or 15% to 50% by weight, based on the total weight of the linear triblock copolymer. In some embodiments, the conjugated diene block (B block) comprises any suitable conjugated diene, for example, a conjugated diene having 4 to 10 carbon atoms, a conjugated diene formed from essentially pure monomeric butadiene monomer or isoprene monomer, or a minor proportion of structurally related conjugated dienes, up to 10% by weight, for example, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene.

[0020] In an embodiment, HSBC is a linear selectively hydrogenated form of a block copolymer having the structure SBS or (SB)2X, where B represents a conjugated diene block or a controlled distribution conjugated diene / styrene block having a peak molecular weight of 50,000 to 290,000 g / mol; or 70,000 to 150,000 g / mol; or 80,000 to 130,000 g / mol, or less than 150,000 g / mol.

[0021] In an embodiment, HSBC is a selectively hydrogenated copolymer having the structure S-EB / SS or (S-EB / S)nX, where X is a coupling agent residue and n is from 1 to 6. The selectively hydrogenated copolymer has a controlled distribution of styrene in the midblock, i.e., EB / S, a total polystyrene content of about 58%, a total molecular weight of about 250 kg / mol, and a melt flow rate of <1 g / 10 min at 230° C. / 2.16 kg.

[0022] In an embodiment, the HSBC is a selectively hydrogenated copolymer having the structure S-EB / SS or (S-EB / S)nX, where X is a coupling agent residue and n is 1 to 6. The selectively hydrogenated copolymer has a controlled distribution of styrene in the midblock, a total polystyrene content of about 35%, a total molecular weight of about 125 kg / mol, and a melt flow rate of about 40 at 230° C. / 2.16 kg.

[0023] In an embodiment, the HSBC is a selectively hydrogenated copolymer having the structure S-EB-S or (S-EB)nX, where X is a coupling agent residue and n is 1 to 6. The selectively hydrogenated copolymer has a total polystyrene content of about 13%, a total molecular weight of about 150 kg / mol, and a melt flow rate of about 9 g / 10 min at 230° C. / 2.16 kg, as set forth in U.S. Pat. No. 6,177,521, which is incorporated by reference.

[0024] In an embodiment, the HSBC is a selectively hydrogenated copolymer having the formula S-EB-S or (S-EB)nX, where X is a coupling agent residue and n is from 1 to 6. The selectively hydrogenated copolymer has a total polystyrene content of about 20%, a total molecular weight of about 67 kg / mol, and a melt flow rate at 230° C. / 2.16 kg of >100 g / 10 min or 100 g / 10 min to 500 g / 10 min.

[0025] In embodiments, the total polystyrene content (PSC) of the selectively hydrogenated block copolymer or the selectively hydrogenated controlled distribution block copolymer is from 10% to 65% by weight; or from 10% to 50% by weight; or from 12% to 45% by weight.

[0026] In embodiments where butadiene is the conjugated diene monomer, the vinyl content of the conjugated diene block (e.g., B block) is in the range of 10 to 95 mol%, 15 to 85 mol%, or 35 to 80 mol%. In embodiments where isoprene is the conjugated diene monomer, the vinyl content of the B block is in the range of 5 to 95 mol%, 5 to 85 mol%, or 5 to 80 mol%.

[0027] In an embodiment, the HSBC is a selectively hydrogenated styrene-diene block copolymer having the formula S-EP-S, (S-EP)nX, S-EEP-S, (S-EEP)nX, S-EB-S, (S-EB)nX, S-EB / SS or (S-EB / S)nX, where S is a polystyrene block, EB is a hydrogenated polybutadiene block, EP is a hydrogenated polyisoprene block, EEP is a hydrogenated polymer block of butadiene and isoprene, n is 12 to 6, and X is a coupling agent residue. The selectively hydrogenated styrene-diene block copolymer is a styrene block copolymer having a polybutadiene block with a vinyl content of 10 to 95 mol % prior to hydrogenation. The selectively hydrogenated styrene-diene block copolymer has a total PSC of 10 wt % to 65 wt %.

[0028] In an embodiment, the selectively hydrogenated styrene-diene block copolymer, prior to hydrogenation, is a styrene block copolymer including a diblock copolymer of formula AB or AB / A, a linear triblock copolymer of formula ABA or AB / AA, or a multi-arm coupling block copolymer of formula (AB)nX or (AB / A)nX, where A is a monoalkenyl arene polymer block, B is a conjugated diene polymer block, B / A represents a polymer block in which the distribution of monoalkenyl arene is controlled in the conjugated diene polymer block, n is 2 to 6, and X is a coupling agent residue. The selectively hydrogenated styrene-diene block copolymer has at least 92 mol% hydrogenated polymerized butadiene units.

[0029] In embodiments, the selectively hydrogenated block copolymer or the selectively hydrogenated controlled distribution block copolymer has a melt flow rate, measured according to ASTM D 1238 at 230° C. and 2.16 kg mass, of 0.01 to 50 g / 10 min; or alternatively 0.1 to 45 g / 10 min; or alternatively 0.5 to 40 g / 10 min.

[0030] The two HSBC components are present in an amount of 100 phr, and the first and second HSBC are present in a weight ratio ranging from 5:95 to 95:5, or 10:90 to 90:10, or 20:80 to 80:20, or 30:70 to 70:30, respectively. In another embodiment, the at least two different HSBC components have a molecular weight ratio of at least 1.2:1, or at least 1.3:1, or at least 1.5:1, or at least 1.7:1, or at least 2.0:1.

[0031] Polypropylene Component In an embodiment, the polypropylene component is selected from the following: (i) homopolymers of propylene, (ii) random copolymers of propylene and ethylene and C4 to C6 copolymers. 10 (iii) an olefin selected from ethylene and C4- 10Random terpolymer of propylene containing two α-olefins selected from the group of α-olefins. C4~ 10 α-olefins are linear and branched C4-olefins such as 1-butene, 1-pentene, 4-methyl-pentene-1,3-methyl-1-butene, 1-hexene, 3-4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene, etc. 10 Contains α-olefins.

[0032] In an embodiment, the propylene component is a homopolymer of propylene. In another embodiment, the propylene polymer is a heterophasic propylene copolymer ("HECO"). The copolymer comprises a polypropylene matrix containing three different polypropylene fractions having different melt flow rates, the HECO having a melt flow rate MFR(230°C) measured according to ISO 1133 of 20.0 g / 10 min or greater.

[0033] In an embodiment, the propylene polymer has a MFR of 2 g / 10 min, or at least 2.1 g / 10 min, or at least 2.2 g / 10 min or greater, as measured by ASTM D1238-82 (230° C. / 5 kg).

[0034] In embodiments, the polypropylene component is present in an amount of from 10 to 55 phr, or less than 50 phr, or at least 20 phr, or from 30 to 45 phr, based on a total amount of 100 phr of the HSBC component.

[0035] Plasticizer component The molding composition optionally includes a dispersing aid or plasticizer selected from aliphatic hydrocarbon oils, fatty acids, triglyceride oils and mixtures thereof. Examples include fatty oils (mixtures of animal or vegetable fatty acid triglycerides), mineral oils and silicone oils.

[0036] In embodiments, the oil is selected from mineral oil, paraffinic oil, paraffin-enriched oil, and mixtures thereof. In some embodiments, the oil is a GTL-based process oil (or Fischer-Tropsch oil). In embodiments, the oil is a synthetic oil. In embodiments, the oil includes diesel, biodiesel, and carboxylic acid esters such as 2-ethylhexyl oleate.

[0037] The plasticizer is present in an amount (based on 100 phr of HSBC total components) of 0 to 55 phr or less than 50 phr or at least 20 phr or 30 to 45 phr.

[0038] Other polymer components In an embodiment, the molding composition optionally comprises other polymeric components selected from thermoplastic polyurethanes, thermoplastic copolyesters and engineering thermoplastics (polyamides, polyesters, polyphenylene ethers), poly(aryl ethers), poly(aryl sulfones), acetal resins, nitrile barrier resins, poly(methyl methacrylate), cyclic olefin copolymers, coumarone-indene resins, polyindene resins, poly(methylindene) resins, polystyrene resins, vinyl toluene-alpha methyl styrene resins, alpha methyl styrene resins and polyphenylene ethers, in particular poly(2,6-dimethyl-1,4-phenylene ether), copolymers thereof; and mixtures thereof.

[0039] Additives In an embodiment, the molding composition further comprises one or more additives selected from nucleating agents, clarifying agents, release agents, antioxidants, stabilizers (such as heat stabilizers, visible light stabilizers, UV stabilizers, etc.), colorants, flame retardants, lubricants (such as calcium stearate), synergists, release agents, flow promoters, antistatic agents, glass fillers, fillers different from glass fillers (such as talc), scratch resistant additives / surface modifiers (such as silicones, low density polyethylene which may be long chain branched low density polyethylene, etc.), or a combination comprising at least one of the foregoing.

[0040] Examples of surface modifiers include ultra-high molecular weight polydialkylsiloxanes such as polydimethylsiloxane, ultra-high molecular weight polydialkylsiloxanes in combination with silica, polyolefin siloxanes, and combinations thereof.

[0041] The additive may be present in an amount of from 1 to 30 phr or less than 25 phr or at least 3 phr or from 5 to 25 phr (based on 100 phr of SBC total components).

[0042] Foaming Agent In an embodiment, a blowing agent (i.e., a propellant) is used in conjunction with a foam injection molding (FIM) process. The blowing agent is not part of the molding composition, but is added as an ingredient in the FIM process in an amount ranging from 1 to 5 weight percent based on the total weight of the molding composition.

[0043] The blowing agent may be either a chemical blowing agent, a physical blowing agent, and / or a microsphere. Examples of physical blowing agents include, but are not limited to, organic blowing agents, such as nitrogen, carbon dioxide, water, aliphatic hydrocarbons such as propane, butane, pentane, and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, etc. Examples of chemical blowing agents include pyrolysis type blowing agents, such as sodium bicarbonate, ammonium bicarbonate, ammonium chloride, ammonium carbonate, etc. Thermally expandable microsphere blowing agents typically include an outer shell of a thermoplastic resin and an expansion agent contained therein.

[0044] Properties of the molding composition The molding composition is characterized by having a melt flow rate in the range of 2 to 50 g / 10 min (230° C., 2.16 kg, measured according to ASTM D1238-04), or at least 5 g / 10 min, or 15 to 40 g / 10 min, or at least 20 g / 10 min, or less than 60 g / 10 min.

[0045] In an embodiment, the composition has a Shore A hardness (15 seconds, 23° C.), measured according to ISO 868, in the range of 60 to 90, or 70 to 90, or at least 65.

[0046] In embodiments, the composition has a melt strength (F) or maximum force of at least 0.010 N, or at least 0.015 N, or at least 0.02 N, or at least 0.03 N. In embodiments, the molding composition has a melt strength (V) or maximum pull-out rate of at least 10, or at least 15, or at least 20, or at least 25, or at least 30, when measured at 230°C.

[0047] Method for forming an article The molding composition can be processed according to methods known in the art by combining the individual components, blending to form a blend, and extruding the blend to form pellets, which are subsequently used to form articles such as injection molded soft skin articles in a molding or extrusion process, for example, a foam injection molding (FIM) process or profile extrusion.

[0048] In an embodiment, the foam injection molding method is a so-called core-back type injection molding method in which the molding composition is injected into a cavity space formed in a mold of an injection molding device, and immediately thereafter or after a predetermined time has elapsed, the movable mold or the movable core provided in the movable mold is pulled back to a predetermined position at a predetermined rate to expand the cavity space, thereby achieving foam molding. Since the temperature of the mold is usually much lower than the temperature of the thermoplastic elastomer composition during injection, a low-foamed high-density skin layer is formed on the surface of the injection foam molding product formed in contact with the surface of the cavity. In an embodiment, the foam product can also be integrally formed in contact with the surface of a prepared base body such as a resin. A laminate can be formed by placing the base body in the cavity space in advance and injecting the composition onto the surface of the base body.

[0049] The compositions can be used in either low-pressure or high-pressure processes. In low-pressure processes, which use a relatively low cavity pressure, the mold cavity is filled with 80-95% polymer gas melt. When the pressure is lowered in the mold, the melt expands and is able to fill the remaining mold volume with a degree of foaming in the range of 5-20%. In high-pressure processes (also known as "precision mold opening" or "breath mold technology"), the mold cavity is completely filled with polymer melt and then immediately opened by a few millimeters. This opening of the cavity creates a pressure drop that allows the melt to foam. The opening step is performed by pulling back the clamping units.

[0050] In embodiments, the foamed article can be formed by foam extrusion. In foam extrusion, the composition is mixed with a suitable blowing agent to form a mixture. An extruder barrel is filled with a melt of the mixture, and the mixture is extruded through a profile die to generate a foamed structure by reducing the pressure and / or temperature. The foamed article is then cut to the desired dimensions.

[0051] Purpose The molding compositions can be used to make many light vehicle applications, particularly door panels, instrument panels and consoles, with integral foam structures having a foam core and dense unfoamed skin layers. In an embodiment, the compositions are used to make shoe sole components, packaging / padding materials, etc. In an embodiment, the compositions are used to make seals, gaskets and synthetic corks.

[0052] Foam products The foamed articles produced by injection molding the composition are characterized by optimized density reduction, improved surface quality, uniform internal porosity, a minimum thickness of non-foamed skin layer, e.g., a high density skin of 0.1-5 mm or less than 2.5 mm or less than 3 mm thick, and a core back or foamed inner core of at least 0.1 mm or at least 1 mm or at least 3 mm or at least 4 mm or 0.1-20 mm thick.

[0053] The foamed articles produced by extruding the composition are characterized by optimized density reduction, improved surface quality, uniform internal porosity, a minimal thickness of non-foamed skin layer, e.g., a high density skin of 0.1 to 3 mm or less than 2 mm thick, and a foamed inner core of 0.1 to 20 mm thick, or at least 0.1 mm thick.

[0054] In an embodiment, the non-foamed skin layer completely covers the foamed inner core of the article.

[0055] In embodiments, the article is characterized by a reduction in density of the molded article in the range of 5-40%, or at least 30%, or at least 15%, or at least 20%, where the reduction in density is obtained by comparing the density after foaming to the density before foaming (i.e., the density of a solid dense polymer). EXAMPLES

[0056] An embodiment is given by way of example.

[0057] The main components used in the examples are as follows: HSBC7 is a medium MW hydrogenated styrene block copolymer with structure (S-EB)nX with a polystyrene content of 13%, a molecular weight of 145 kg / mol, and a midblock (EB) vinyl content of 44% before hydrogenation.

[0058] HSBC8 is a low MW styrene block copolymer with structure (S-EB)nX with a polystyrene content of 20%, a molecular weight of 67 kg / mol, and a midblock (EB) vinyl content of 77% before hydrogenation.

[0059] HSBC5 is a high MW styrene block copolymer with structure S-EB / SS, with a polystyrene content of 58%, a molecular weight of 245 kg / mol, and a midblock (S / EB) vinyl content before hydrogenation of 38%.

[0060] HSBC1 is a medium MW styrene block copolymer with structure (S-EB / S)nX with a polystyrene content of 34%, a molecular weight of 125 kg / mol, and a midblock (S / EB) vinyl content of 77% before hydrogenation.

[0061] HSBC3 is a low MW styrene block copolymer backbone with structure (S-EB)nX with a polystyrene content of 30%, a molecular weight of 57 kg / mol, and a midblock (EB) vinyl content of 38% before hydrogenation.

[0062] PP125 is a long-chain branched polypropylene resin with a melt flow (230° C. / 2.16 kg) of 2.4 g / 10 min, a tensile strength of 40 MPa, and an elongation at yield of 6%.

[0063] PP140 is another long chain branched polypropylene resin with a melt flow (230° C. / 2.16 kg) of 2.1 g / 10 min, a tensile strength of 40 MPa, and an elongation at yield of 6%.

[0064] PP2030 is a homopolypropylene resin with a melt flow (230°C / 2.16 kg) of 2.5 g / 10 min.

[0065] PP185 is another homopolypropylene with a melt flow (230°C / 2.16 kg) of 2.2 g / 10 min.

[0066] PP348 is a polypropylene random copolymer resin with a melt flow (230° C. / 2.16 kg) of 11 g / 10 min, a tensile strength of 29 MPa, and an elongation at yield of 13%.

[0067] Examples 1 to 20 The ingredients shown as weight percent in the table were blended and extruded to form pellets which were subsequently used to form foamed articles in a core-back injection molding process.

[0068] The properties of the molding compositions were measured and are shown in Tables 1 and 2. For melt strength measurements, the Rheotens test was carried out using a four-wheel device under the extruder with a rotation length of 100 mm and an extruder throughput of 0.5 kg / h. The equipment is operated by cooling with alcohol. From the measured data, value curves are calculated and the Wagner extensional viscosity model is applied.

[0069] For the foamed articles, an injection foam molding machine equipped with a three-zone extruder was used with a test plate of 90x90x2 mm. The mold temperature was varied from 40°C to a maximum of 220°C (T-mold at 40°C, T-zone 1 at 220°C, T-zone 2 at 190°C and T-zone 3 at 180°C). The injection rate was 90% and the injection time was 0.58 seconds. The back pressure was 23 bar and the back pressure time was 4 seconds. The foaming agent included a physical blowing agent (0.8% CO2) and a chemical blowing agent of 2.0% hydrocerol CF40E. The produced foamed articles show a skin thickness of about 2 mm with a high density skin / foam thickness ratio of 1.0-2.0. The standard density reduction before and after foaming was determined using a hydrostatic balance.

[0070] The results are shown in Table 1-2. Figure 1 is an optical microscope image of the cross section of the foamed sample obtained from the formulation of Example 9.

[0071] [Table 1]

[0072] [Table 2]

Claims

1. 100 phr of at least two different hydrogenated styrenic block copolymers, a first hydrogenated styrenic block copolymer and a second hydrogenated styrenic block copolymer, each having different molecular weights with a molecular weight ratio of at least 1.2:1 and a weight ratio in the range of 5:95 to 95:5, respectively, wherein prior to hydrogenation, at least one of the first and second hydrogenated styrenic block copolymers has a molecular weight of at least 1.2:1 and a weight ratio in the range of 5:95 to 95:5, ｎ a hydrogenated styrene block copolymer which is a multi-arm coupled block copolymer of X, where A is a monoalkenyl arene block, B is a conjugated diene block, n is an integer from 2 to 4, and X is the residue of a coupling agent; 10 to 55 phr polypropylene having a melt flow of at least 2 g / 10 min according to ASTM D1238-82 (230° C. / 5 kg); and up to 55 phr of a plasticizer selected from hydrocarbon-based oils, fatty acids, triglyceride oils, and mixtures thereof; 1. A foamed article made from a composition consisting essentially of: the composition has a melt flow rate (230° C., 2.16 kg, measured by ASTM D1238-04) of 2 to 50 g / 10 min, a Shore A hardness (15 sec, 23° C.) of 60 to 90 as measured according to ISO 868, a melt strength (F) of at least 0.010 N, and a melt strength (V) of at least 10; The foamed article is formed by foam injection molding or foam extrusion; the foamed article has a density that is at least 10% reduced relative to an article formed from an unfoamed composition; A foamed article, said foamed article having a non-foamed skin layer completely covering a foamed inner core.

2. 2. The foamed article of claim 1, wherein the non-foamed skin layer has a thickness of 0.1 to 5 mm.

3. 10. The foamed article of claim 1, wherein the foamed inner core has a thickness of 0.1 to 20 mm.

4. 4. The foamed article of any of claims 1 to 3, wherein the composition further comprises one or more other polymeric components selected from the group consisting of thermoplastic polyurethanes, thermoplastic copolyesters, and engineering thermoplastics (polyamides, polyesters, polyphenylene ethers), poly(aryl ethers), poly(aryl sulfones), acetal resins, polyamides, nitrile barrier resins, poly(methyl methacrylate), cyclic olefin copolymers, coumarone-indene resins, polyindene resins, poly(methylindene) resins, polystyrene resins, vinyl toluene-alpha methyl styrene resins, alpha methyl styrene resins, and polyphenylene ethers, poly(2,6-dimethyl-1,4-phenylene ether), copolymers thereof, and mixtures thereof.

5. The foamed article of any one of claims 1 to 3, wherein the molding composition further comprises 1 to 30 phr of an additive per 100 phr of the at least two different hydrogenated styrenic block copolymers.

6. The foamed article of any one of claims 1 to 3, wherein one of the first and second hydrogenated styrene block copolymers is a multi-arm coupled block copolymer of formula (A-B)nX and the other hydrogenated styrene block copolymer is selected from selectively hydrogenated styrene-diene block copolymers, selectively hydrogenated styrene-diene-styrene triblock copolymers, selectively hydrogenated styrene-diene diblock copolymers, selectively hydrogenated resins of styrene-diene-styrene triblock copolymers, selectively hydrogenated styrene-diene random copolymers, selectively hydrogenated controlled distribution styrene-diene / styrene block copolymers, selectively hydrogenated controlled distribution styrene-diene / styrene-styrene block copolymers, and combinations thereof.

7. 7. The foamed article of claim 6, wherein the selectively hydrogenated styrene-diene block copolymer, prior to hydrogenation, is a styrene block copolymer comprising a diblock copolymer of formula A-B or A-B / A, a linear triblock copolymer of formula A-B-A or A-B / A-A, or a multi-arm coupled block copolymer of formula (A-B)X or (A-B / A)X, where A is a monoalkenyl arene polymer block, B is a conjugated diene polymer block, B / A represents a polymer block having a controlled distribution of monoalkenyl arene in the conjugated diene polymer block, n is 2 to 4, and X is a coupling agent residue.

8. 7. The foamed article of claim 6, wherein the selectively hydrogenated styrene-diene block copolymer has the formula S-EP-S, (S-EP)nX, S-EEP-S, (S-EEP)nX, S-EB-S, (S-EB)nX, S-EB / S-S, or (S-EB / S)nX, where S is a polystyrene block, EB is a hydrogenated polybutadiene block, EP is a hydrogenated polyisoprene block, EEP is a hydrogenated polymer block of butadiene and isoprene, n is 2 to 4, and X is a coupling agent residue.

9. 8. The foamed article of claim 7, wherein the selectively hydrogenated styrene-diene block copolymer is a styrene block copolymer having a polybutadiene block with a vinyl content of 10 to 95 mol % prior to hydrogenation.

10. 8. The foamed article of claim 7, wherein the selectively hydrogenated styrene-diene block copolymer has a total polystyrene content of from 10% to 65% by weight.

11. 8. The foamed article of claim 7, wherein at least 92 mol % of the polymerized butadiene units of the selectively hydrogenated styrene-diene block copolymer are hydrogenated.

12. The foamed article of any one of claims 1 to 3, wherein the blowing agent is present in an amount of 1 to 5% by weight, based on the total weight of the molding composition.

13. 4. The foamed article according to any one of claims 1 to 3, wherein the foamed article is for light vehicle applications selected from the group consisting of door panels, instrument panels and consoles; shoe sole components, packaging and padding materials.

14. A method for producing a foamed article according to any one of claims 1 to 3 by an injection molding process, comprising the steps of: a) mixing the composition with a suitable blowing agent to form a mixture; b) filling a mold cavity with a melt of said mixture using an injection molding process; c) foaming the mixture in the mold cavity by reducing the pressure and / or increasing the temperature; and d) removing the foam from the mold cavity. A method comprising:

15. A method for producing a foamed article according to any one of claims 1 to 3 by an extrusion process, comprising the steps of: a) mixing the composition with a suitable blowing agent to form a mixture; b) filling an extruder barrel with a melt of said mixture; c) extruding the mixture through a profile die and reducing the pressure and / or temperature to produce a foamed structure; and d) Cutting the foam to the desired length. A method comprising:

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