MXPA01009223A - Olefin polymers and alpha-olefin/vinyl or alfa-olefin/vinylidene interpolymer blend foams - Google Patents

Abstract

A polymer blend foam having smooth skin and/or an open-cell content of at least 20 volume percent, a crosslinked gel content of no greater than 10 percent, a minimum cross-sectional area of at least 1000 mm2, and a density of no greater than 250 kg/m3. The blend includes (A) a substantially random interpolymer having polymerized therein (1) a vinyl or vinylidene aromatic monomer and/or sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer, and (2) one or more of ethylene and a C3-20 aliphatic&agr;-olefin;and (B) an olefin polymer based on one or more of ethylene, C3-20 aliphatic&agr;-olefins, and C3-20 aliphatic&agr;-olefins containing polar groups. The olefin polymer (B) lacks any of the vinyl or vinylidene aromatic monomers found in (A).

Description

OLEFIN POLYMERS AND ALPINE-OLEFINE INTERPOLIMER MIXING FOAMS / VINYLIDENE OR ALPHA-OLEFINE / VINYL BACKGROUND OF THE INVENTION This invention relates generally to polymer foams based on a mixture of an olefin polymer and at least one interpolymer of alpha-olefin (α-olefin) / vinyl monomer and a monomer interpolymer of a -olefin / vinylidene. The vinyl and vinylidene monomers may be aromatic, aliphatic or cycloaliphatic, sterically hindered. This invention relates particularly to open cell polymer foams based on such blends, especially when the foams are soft and flexible and, preferably, of low density. This invention also relates to low density polymer foams (either open cell or closed cell) based on such blends which more preferably have a skin that is uniform, aesthetically attractive and, even more preferably, functionally improved in relation to to foams prepared exclusively from an olefin polymer. These foams are preferably substantially free of degradation as demonstrated by a low gel content. A variety of thermoplastic polymers find their way into polymer foams. Certain thermoplastic polymers foam more easily than others to provide structures with a variety of useful properties and dimensions. For example, polystyrene is an amorphous polymer that foams over a relatively wide range of temperatures, producing foams with a wide range of open cell contents. On the other hand, semi-crystalline polymers typically foam over a narrow range of temperature (related to polystyrene) as their viscosities and melting strengths drip rapidly as temperatures exceed their crystalline melting points. This usually results in foams with a predominantly closed cell configuration. A medium for increasing the melting strength of semi-crystalline polymers, which thereby broadens the temperature range and improves a range of processing characteristics, includes slightly degrading the polymers by peroxides, irradiation or other conventional means. Even so, the resulting foams typically have a configuration that is predominantly closed cell (less than 20 volume percent (% vol) of open cell content). Low density, non-degraded olefin polymer foams typically have rigid skins in processing. As the foams grow, the stiffness of the skin can be increased due to contraction or expansion. Rigid skin lacks aesthetic appeal in several applications (eg, pad packaging). This leads to its removal at the time of final foam manufacture and results in waste material. PCT application number WO / 9810015 discloses blends of polyolefins and intepolymers of α-olefin / vinylidene monomer. Examples 26, 27 and 29-31 relate to the foam materials prepared from such mixtures. Example 26 reports foam materials with a length of 32 millimeters (mm) and a thickness of either 1 5 mm or 17 mm. Example 27 has a length of 34.5 mm and a thickness of 19 mm. Examples 29-31 show the closed cell preparation (less than (<) 20 percent (%) of open cell content), but do not report foam size.

BRIEF DESCRIPTION OF THE INVENTION One aspect of this invention is a polymer foam having a degraded gel content of not more than 10%, (preferably with a minimum cross-sectional area of at least 1000 mm2), and a density < 250 kilograms per cubic meter (kg / m3), wherein at least 70 weight percent (% by weight) of the polymers in the foam comprises a mixture of: (A) from 5 to 60% by weight, based on to the combined weight of components (A) and (B), of at least one substantially random interpolymer having a melt index of 0.05 to 1000 grams per 10 minutes (g / 10 min), either a crystalline melting point ( Tm) or a vitreous transition temperature (Tg) of about 80 ° C or less, whichever is appropriate, and: (1) from 8 to 65% mol percent (mol%) of its monomer units derived from; (a) at least one aromatic vinyl or vinylidene monomer, or (b) at least one aliphatic or cycloaliphatic monomer sterically hindered, or (c) a combination of at least one vinyl or vinylidene aromatic monomer and at least one vinyl monomer or aliphatic or cycloaliphatic vinylidene. (2) from 35 to 92% mol of its monomer units derived from ethylene, an aliphatic α-olefin containing from 3 to 20 carbon atoms (C3-20), or a mixture thereof; and having at least 80 mol% of its monomer units derived from (1) and (2); and (B) from 95 to 40% by weight, based on the combined weight of the components (A) and (B), of at least one polymer that does not have monomer units derived from (1) (a), (1) (b), or (1) (c), and at least 80 mol% of its monomer units derived from the monomers selected from ethylene, C3-20 aliphatic α-olefins, and a C3.20 aliphatic α-olefin containing a polar group. The mixture may contain other polymerizable monomers; and the foam may contain one or more conventional foam promoters, additives or both. The foam may also have an open cell content of at least 20 volume percent (vol%), based on the total foam volume. One needs to not use degradation to increase the melting strength of the polymer, add filler parts, such as natural gas carbon black, that break cell walls, or mechanically break cell walls in order to achieve such open cell content . The glass transition temperatures (Tg) and crystalline melting points (Tm) of component (A) or (B) are measured using a differential scanning calorimeter (DSC). The following procedure is used for DSC measurements: the sample is heated rapidly to 180 ° C; maintained at 1 80 ° C for 4 minutes to ensure complete fusion; cooled to 1 0 ° C / min to approximately 40 ° C below the expected Tg; maintained at this temperature for four minutes for the stabilization of DSC; and heated to 150 ° C at 10 ° C / min. The Tm is obtained from the melting curve and is the maximum melting temperature. The Tg is obtained using the average height method of the DSC melting curve (also called second heat). The present invention also relates to an extrusion foaming process for preparing the polymer foam. The process comprises: (I) converting the mixture into a polymer melt; (II) introducing, at an elevated temperature, at least one blowing agent into the polymer melt to form a foamable gel, the blowing agent being presented in a total amount of from 0.2 to 5.0 grams-moles per kilograms (gM / kg) of the polymers contained in the polymer melt; (I I I) cooling the foamable gel to an optimum temperature; and (IV) removing the foamable gel from Step III through a nozzle to a lower pressure region to form a foam.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES All references herein to the elements or metals belonging to a certain Group refer to the Periodic Table of the Elements published and registered by CRC Press, Inc., 1989.

Any reference to the Group or Groups must be to the Group or Groups as reflected in the Periodic Table of the Elements using the lUPAC system for numbering groups. Unless stated otherwise, all ranges include both endpoints and all numbers between the endpoints. "Hydrocarbyl" means any of the aliphatic, cycloaliphatic, aromatic, substituted aliphatic groups of aryio, substituted aryl cycloaliphatics, aliphatic substituted aromatics, or aliphatic substituted cycloaliphatics. "Hydrocarbyloxy" means a hydrocarbyl group having an oxygen bond between the and carbon atom to which it is attached. "Aliphatic" means a compound that has a branched or straight chain grouping of its carbon atoms. "Copolymer" means a polymer having polymerized therein monomer units derived from two different monomers. "Interpolymer" means a polymer that has polymerized therein monomer units derived from at least two different monomers. This includes copolymers, terpolymers and tetrapolymers. "Monomeric unit" refers to a main part of the polymer that is derived from a single monomer. "Open Cell Foam" refers to foaming with an open cell content of at least (>) 20% vol. according to ASTM D2856-94. "Soft Foam" means a foam having an Inquisitor C, hardness of < 80, preferably < 70, more preferably < 60 at a foam density of 250 kg / m3 or less (<). Components (A) "Substantially random interpolymers" (SRIPs) of the present invention have a monomer distribution capable of being described by a Bernoulli statistical model or by a first or second order Markovian statistical model, as described by J.C. Randall in POLYMER SEQÚENSE DETERMINED, Carbon-1 3 NMR Meted, Academic Press New York, 1 977, p. 71 -78. Preferred SRIPs have a vinyl aromatic monomer distribution such that < 15% of total vinyl aromatic monomer content occurs in vinyl aromatic monomer blocks of more than (>) 3 units. More preferably, the ether polymer lacks a high degree of either isotactivity or syndiotacticity. This means that, in its 1 3 carbons nuclear magnetic resonance spectrum (C13-NMR), an SRIP has corresponding maximum areas for maintaining methine and methylene chain carbons that represent either bivalent radical meso sequences or bivalent radical sequences. racemes that do not exceed 75% of the maximum area of maintaining the methine and methylene carbons in chain. The SRIPs are presented in foams of the present invention as part of the component (A) resulting in the polymerization of i) one or more of ethylene and an aliphatic α-olefin monomer (C3-20), ü) one or more vinyl or vinylidene aromatic monomers and aliphatic or cycloaliphatic vinylidene monomers or sterically hindered, and, optionally, (iii) up to 20% mole of an ethylene-polymerizable unsaturated monomer unlike that of i) and ii). Interpolymers have >; 80% mol, preferably > 90% mol and more preferably 100 mol% of its monomer units derived from (i) and (ii). Suitable a-olefins are aliphatic α-olefins containing from 3 to 20, preferably from 3 to 12, more preferably from 3 to 8 carbon atoms (C3-2o, C3-? 2, C3-β) - As used in the present, the subscripts indicate the number of, for example, carbon atoms (C) contained in a monomer. Particularly suitable α-olefins include ethylene, propylene, butene-1,4-methyl-1-pentene, hexene-1 or octene-1, or ethylene in combination with one or more of propylene, butene-1,4-methyl- 1 -pentene, hexene-1 and octene-1. Other ethylenically optional polymerizable unsaturated comonomers include norbornene and substituted C.sub.80 alkyl or C6-? Or aryl norbornes, with an exemplary interpolymer being ethylene / styrene / norbornene. Vinyl or vinylidene aromatic monomers suitable for use in Component (A) include those represented by the formula: FORMULA wherein R1 is a radical selected from hydrogen and lower (C?) Alkyl radicals, preferably hydrogen or methyl; each R2 is a radical independently selected from hydrogen and C? alkyl radicals? , preferably hydrogen or methyl; Ar is a phenyl group or phenyl group substituted with from 1 to 5 substituents or selected portions of a halogen (or halo-), C 1. 14 alkyls, and C 1-4 haloalkyls; and n is an integer from zero (0) to 4, preferably from 0 to 2, more preferably 0. Vinyl aromatic monomers include styrene, vinyl toluene, α-methylstyrene, t-butyl styrene, chlorostyrene, as well as their isomers . Particularly suitable vinyl aromatic monomers include styrene and its substituted alkyl (C ^^) or halogen (eg, or bromine) derivatives. Preferred monomers include styrene, α-methyl styrene, substituted alkyl or lower styrene ring derivatives, such as ortho-, meta-, and para-methylstyrene, annular halogenated styrenes, para-vinyl toluene or mixtures thereof. A more preferred vinyl aromatic monomer is styrene. An "aliphatic or cycloaliphatic vinylidene or sterically hindered vinylidene compound" is an addition of polymerizable vinyl or vinylidene monomer corresponding to the formula: FORMULA wherein A1 is a cyclic aliphatic group Ce-20, tert-butyl, or a substituted norbornyl group or unsubstituted; R 3 is hydrogen or a C 1-6 alkyl group, preferably hydrogen or methyl; and each R 4 is independently selected from hydrogen or a C 1 - 4 alkyl group, preferably hydrogen or methyl; or alternatively, R3 and A1 together form a ring system. Preferred aliphatic or cycloaliphatic vinylidene or vinylidene compounds include monomers in which one of the carbon atoms bearing the ethylenic unsaturation is tertiary or substituted quaternary. Examples of suitable substituents A1 include cyclohexyl, cyclohexenyl, and cyclooctenyl. More preferred compounds include various substituted cyclohexene vinyl ring derivatives and substituted cyclohexenes and 5-ethylidene-2-borbornene. Especially suitable compounds include 1 -, 3-, and 4-vinylcyclohexene. The preparation of SRIP includes polymerizing a mixture of polymerizable monomers in the presence of one or more metallocene or forced geometry catalysts in combination with various cocatalysts, as described in EP-A-0,416,815 and U.S. Patent No. (USP) 5,703 , 187, of which are incorporated herein by reference in their entirety. Preferred polymerization conditions include atmospheric pressures up to 3000 atmospheres (304 megapascals MPa)) and temperatures from -30 ° C to 200 ° C. Polymerization and removal of the unreacted monomer at temperatures above the monomer autopolymerization temperatures of the respective monomers may convert some monomer into its respective homopolymer by a mechanism such as free polymerization. Examples of suitable catalysts for preparing SRIPs and process conditions are described in the U.S. Application. Serial No. 702,475, filed May 20, 1991 (EP-A-514,828); as well as USPs 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5, 132,380; 5, 189, 192; 5,321, 106; 5,347,024; 5,350,723; 5,374,696; 5,399,635; 5,470,993; 5,703, 187; and 5,721, 185 of which all patents and applications are incorporated herein by reference. The SRIP preparation suitably occurs at temperatures of from -30 ° C to 250 ° C in the presence of a catalyst represented by the formula: FORMULA wherein: each Cp1 is independently, for any case, a p-bond of cyclopentadienyl group substituted with M; E is C or Si; M is a metal group IV, preferably Zr or Hf, more preferably Zr; each R5 is independently, in each case, H, hydrocarbyl, silahydrocarbyl, hydrocarbylsilyl, containing up to 30, preferably from 1 to 20, more preferably from 1 to 10 carbon atoms (C) or silicon (Si); each R6 is independently, in each case, H, halo, hydrocarbyl, hydrocarbyloxy, silahydrocarbyl, hydrocarbylsilyl containing up to 30, preferably from 1 to 20, more preferably from 1 to 10 C atoms or Si of the two groups together can be a , Substituted hydrocarbyl 3-butadiene C ^ o; and m is 1 or 2. Optionally, but preferably, the polymerization occurs in the presence of an activating cocatalyst. Particularly suitable substituted cyclopentenyl groups include those illustrated by the formula: FORMULA wherein each R7 is independently, in each case, H, hydrocarbyl, silahydrocarbyl, or hydrocarbylsilyl and contains up to 30, preferably 1 to 20, more preferably 1 to 10 C or Si atoms or two R7 groups together form a divalent derivative of such a group. Preferably, R7 is independently, in each case, (including when all isomers are suitable), hydrogen (H), methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, phenyl, or silyl or (where appropriate) two R7 groups are joined together to form a fused ring system such as indenyl, fluoroenyl, tetrahydroindenyl, tetrahydrofluorenyl, or octahydrofluorenyl.

Particularly preferred catalysts include, for example, racemic zirconium dichloride-dimethylsilanediyl) -bis- (2-methyl-4-phenylindenyl), racemic 1,4-diphenyl-1,3-butadiene- (dimethylsilanediyl) -bis- (2 -methyl-4-phenylindenyl), di-C C. 4 -alkyl of racemic zirconium- (dimethylsilanodiM) -bis- (2-methyl-4-phenylindenyl) Di-alkoxide C? _4 of racemic zirconium- (dimethylsilanediyl) -bis- (2-methyl-4-phenylindenyl), or a combination thereof. Forced geometry catalysts based on suitable titanium include dimethyl of [N- (1,1-dimethylethyl) -1, 1-dimethyl-1 - [(1, 2,3,4,5-h) -1,5 , 6,7-tetrahydro-s-indacen-1 -yl] silanaminate (2 -) - N] titanium; dimethyl titanium (1-indenyl) (tert-butylamido) dimethylsilane: dimethyl titanium ((3-tert-butyl) (1, 2,3,4,5-h) -1-indenyl) (tert-butylamido dimethylsilane; and titanium dimethyl ((3-iso-propyl) (1, 2,3,4,5-h) -1-indenyl) (tert-butylamido) dimethylsilane, or any other combination thereof. Other methods of preparing interpolymers suitable for use in the present invention are described in various references. Longo and Grassi (Makromol, Chem., Volume 191, pages 2387 to 2396 [1990]) and D'Anniello et al. (Journal of Applied Polymer Science, Volume 58, pages 1701-1706 (1995)) report the use of a catalytic system based on methylalumoxane trichloride (MAO) and cyclopentandienyl-titanium (CpTiCI3) to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am. Chem. Soc, Div. Polym. Chem.) Volume 35, pages 686,687 [1994]) report using a MgCl 2 / TiCl / NdCl 3 / AI (iBu) 3 catalyst to give random copolymers of styrene and propylene. I went to al. (Journal of Applied Polymer Science, volume 53, pages 1453 to 1460 [1994]) describe the copolymerization of ethylene and styrene using a TiCl4 / NdCI3 / MgCl2 / AI (Et) 3 catalyst. Semetz and Mulhaupt, (Macromol. Chem. Phys., V. 197, pp. 1071 -1083, 1997) describe the influence of polymerization conditions on the copolymerization of styrene with ethylene using the Me2Si (Me Cp) catalysts (N -ter-butyl) -TiCl2- / methylaluminoxane Ziegler-Natta. Arai, Toshiaki and Suzuki (Polymer Preprints, Am. Chem. Soc. Div. Polym describe the ethylene-styrene copolymers produced by metallocene catalysts in Chem bridge.) Volume 38, pages 349, 350 [1997]) and in USP 5,652.31 5. The preparation of the α-olefin / vinyl aromatic monomer interpolymers such as propylene / styrene and butene / styrene are described in USP 5, 244,996 or USP 5,652,315 or as described in DE 197 1 1 339 A1. All of the above methods described for the preparation of the interpolymer component are incorporated herein by reference. Also, although the high isotacticity and therefore not "substantially random", the random copolymers of ethylene and styrene are described in Polymer Preprints Vol. 39, No. 1, March 1998 by Toru Aria et al. they can also be used as mixing components in the manufacture of foams of the present invention. SRIPs can also be prepared by the methods described in JP 07/278230 using the compounds shown by the general formula: FORMULA wherein Cp2 and Cp3 are cyclopentadienyl groups, indenyl groups, fluorenyl groups, or substituents thereof, independently of each; R8 and R9 are H atoms, halogen atoms, d.12 hydrocarbon groups, alkoxy groups, or aryloxyl groups, independently of each; M is a group IV of metal, preferably zirconium (Zr) or aluminum (Hf), more preferably Zr; and R10 is an alkylene group of silanediyl group used to degrade Cp2 and Cp3. SRIPs can also be prepared by the methods described in WO 95/32095; WO 94/00500; and in Plastics Technology, p. 25 (September 1992), all of which are incorporated herein by reference in their entirety. Also suitable are SRIPs comprising at least one α-olefin / vinyl aromatic / vinyl aromatic / α-olefin tetrahedro as described in the U.S. Application. No. 08 / 708,869 filed September 4, 1996 and WO 98/099999. The SRIP preparation can also produce an amount of atactic vinyl aromatic homopolymer. The amount typically produces few deleterious effects in relation to the present invention and can be tolerated. If desired, one can separate such homopolymer from the desired interpolymer by conventional techniques. For purposes of the present invention, the amount is desirably < 30% by weight, and preferably 20% by weight, based on the combined weight of interpolymer and atactic vinyl aromatic homopolymer. The SRIPs can be modified by conventional methods such as grafting, hydrogenation and, operation such as sulfonation or chlorination. The SRIPs have an aromatic monomer content of vinyl or vinylidene and / or a substantially hindered aliphatic or cycloaliphatic monomer (1) which is probably from 8 to 65 (8-65), and more preferably 1-565% mol. The interpolymers also have an aliphatic ethylene and / or α3-olefin content of C3.20 (2) which is preferably from 35 to 92, and more preferably from 35-85 mol%, especially when foams of uniform skin are prepared. The mole percentages are based on combined moles of (1) and (2) and in each case total 100 ° mole. The SRIP (component (A)) has a melt index (12) which is desirably 0.05-1 000, preferably 0.1-100, and more preferably 0.2-50 g / 10 min as measured by American Society for Testing and Materials ( Test ASTM D1238, 190 ° Centigrade (° C) /2.16 kilogram (kg) of weight). It also has a molecular weight distribution (weight average molecular weight / number average molecular weight (Mw / Mn) or MWD) of 1.5- 20, preferably 1.8-8, and more preferably 2-5. Component (B) Olefin polymers suitable for use as a blending component (B) include those which do not have monomeric units of a vinyl aromatic or vinylidene monomer or an aliphatic or cycloaliphatic vinylidene or vinylidene monomer sterically hindered and > 80% mol, preferably > 90 mol%, and more preferably 100 mol%, based on the total moles of the monomer units, of their monomer units derived from > 1 monomer selected from ethylene, unsubstituted aliphatic C3.20 α-olefins, or aliphatic C3 α-olefins containing polar group. The olefinic polymers can be homopolymers, copolymers or interpolymers. Suitable aliphatic aliphatic α-olefin monomers include, for example, ethylene-unsaturated nitriles such as maleic anhydride; ethylenically unsaturated amides such as acrylamide or methacrylamide; ethylene-unsaturated carboxylic acids (both mono- and dysfunctional) such as acrylic acid or methacrylic acid; esters (especially lower, for example, C este-C 6 alkyl esters) of ethylene-unsaturated carboxylic acids such as methyl methacrylate, methyl acrylate, hydroxyethyl acrylate, n-butyl acrylate or methacrylate, or 2-ethyl- hexyl acrylate; ethylenically unsaturated dicarboxylic acid imides such as N-alkyl or N-aryl maieimides such as the N-phenyl maleimide. Preferred polar group-containing monomers include acrylic acid, vinyl acetate, maleic anhydride and acrylonitrile. The olefinic polymers may contain a halogen such as fluorine, chlorine or bromine. Preferred halogen-containing olefinic polymers include chlorinated polyethylenes (CPEs). Preferred olefinic polymers include homopolymers or interpolymers of ethylene or of aliphatic α2-olefins C2.18 (including cycloaliphatic). Examples of such preferred polymers include ethylene or propylene homopolymers, and interpolymers of two or more monomers of C2.18 α-olefins. Other preferred olefinic polymers include interpolymers of ethylene and one or more other C3.8 α-olefins such as 1-butene, 4-methyl-1-pentene, 1 -hexene or 1-ketene. While substantial release of degradation may be preferred, one may employ conventional means to slightly degrade the polymers in either or both components (A) and (B), such that the polymers exhibit increased deviation refinement, but remain thermoplastics. Such means include, for example, irradiation, the use of an adhesion agent such as (but not limited to) an azide or a peroxide. This level of degradation tends to increase the melting strength of the polymer which, in turn, leads to improvements in at least one of the properties of foamability, interfacial resistance and mechanical properties. Examples of polymers modified in this novelty are PROFAX ™ PF814 (a product of Montell) and DAPLOY ™ 130D (a product of Borealis) of PP of high melt strength. "Adhesion agent", as used herein, means a compound or mixture of compounds used for coupling purposes and, optionally, foaming, a polymer or polymer mixture. Typical coupling compounds are polyfunctional and capable of insertion reactions at the C-H bonds. Such polyfunctional compounds have >; two, preferably two, functional groups capable of C-H insertion reactions. Suitable adhesion agents include, but are not limited to, cure systems based on peroxide, silane, sulfur, radiation, or azide. A full description of various degradation technologies is described in the co-pending US Patent Application. Nos. 08/921, 641 and 08/921, 642, both filed on August 27, 1997 and incorporated herein by reference in their entirety. Dual cure systems, which use a combination of heat, moisture cure, and radiation stages, can be used effectively. Dual cure systems are described and claimed in the U.S. Patent Application. Serial No. 536,022, filed September 29, 1995, the teachings of which are incorporated herein by reference. For example, it may be desirable to employ peroxide bonding agents together with the silane adhesion agents, peroxide bonding agents together with the radiation, sulfur-containing bonding agents together with silane adhesion agents, etc. Polyfunctional compounds capable of insertions into CH bonds also include carbene-forming compounds such as the salts of alkyl and aryl hydrazones and diazo compounds, and nitrene-forming compounds such as alkyl and aryl azides (R-N3), acyl azides (RC (O) N3), azido-formmates (ROC (O) -N3) such as tetramethylenebis (azido-formate) (see USP 3,284,421); sulfonyl azides (R-SO2-N3), phosphoryl azides ((RO) 2- (PO) -N3), phosphinic azides (R2-P (O) -N3) and silyl azides (R3-Si-N3) . The poly (sulfonyl azides) are any of the compounds that have > two reactive sulfonyl azide groups (-SO2N3). Preferred poly (sulfonyl azides) have an XRX structure wherein each X is SO2N3 and R represents a hydrocarbyl, hydrocarbyl ether or silicon containing inertly substituted or unsubstituted group, preferably having sufficient carbon, oxygen or silicon, preferably carbon, atoms to separate the azide sulfonyl groups to allow an easy reaction between an SRIP and a suffonyl azide, more preferably > 1, more preferably > 2, more preferably > 3 carbon, oxygen or silicon, preferably carbon, atoms between the functional groups. "Inertly substituted" refers to a substitution with atoms or groups that do not undesirably interfere with the desired reaction (s) or the desired properties of the resulting degraded polymers. Such groups include fluorine, aliphatic or aromatic ether, siloxanes, as well as azide sulfonyl groups when > Two SRIP chains are to join. Suitable structures include R as aryl, alkyl, alkaryl aryl, arylalkyl, or heterocyclic silane and other groups that are inert and separate the azide sulfonyl groups as described. More recently, R includes > an aryl group between the sulfonyl groups, more preferably > two aryl groups (such as when R is 4,4'-diphenyl ether or 4,4'-biphenyl). When R is an aryl group, the aryl group preferably has > a ring, as in the case of naphthylene (bis sulfonyl azides). The poly (sulfonyl) azides include such components as 1, 5-pentene bis (sulfonyl azide), 1,8-octane bis (sulfonyl azide), 1, 10-decane bis (sulfonyl azide), 1, 10-octadecane bis ( sulfonyl azide), 1-octyl-2,4,6-benzene tris (sulfonyl azide), 4,4'-diphenyl ether bis (sulfonyl azide), 1,6-bis (4'-sulfonazidophenyl) hexane, 2,7 -naphthalene bis (axid sulfonyl), and sulfonyl azides of aliphatic hydrocarbons containing an average of 1 -8 chlorine atoms and 2-5 azida sulfonyl groups per molecule, and mixtures thereof, were mixed. Preferred poly (sulfonyl azides) include oxy-bis (4-sulfonylazidobenzene), 2,7-naphthalene bis (sulfonyl azido), 4,4'-bis (sulfonyl azido) biphenyl, 4,4'-diphenyl ether bis ( sulfonyl azide) and bis (4-sulfonyl azidophenyl) methane, and mixtures thereof.

The poly (sulfonyl azide) and the polymer or mixture to be coupled are mixed at a first temperature i.e. > the melting point of the lower melting component of the mixture and, after mixing, they are heated to react at a second temperature which is > the first temperature and it is, and usually it is > 100 ° C and more frequently 150 ° C. The preferred temperature range depends on the nature of the azide that is used. To be coupled, the sulfonyl azide is mixed with the polymer and heated to at least the decomposition temperature of the sulfonyl azide. "Decomposition Temperature" means the temperature at which an azide is converted to its sulfonyl nitrene, removing nitrogen and heat in the process, as determined by differential scanning calorimetry (DSC). Other adhesion agents include phenols, aldehyde-amine reaction products, substituted ureas, substituted guanidines; substituted xanthates; substituted dithiocarbamates; sulfur-containing compounds, such as thiazoles, imidazoles, sulfenamides, thiuramidisulfides, paraquinoneximexime, dibenzoparaquinone dioxime, azfure; and combinations thereof. See, Encvclpedia at Chemical Techonology. Vol. 17, 2a. Edition, Interscience Publishers, 1968; and Organic Peroxides, Daniel Seem, Vol. 1, Wiley-lnterscience, 1970). Suitable peroxides include aromatic peroxides; aliphatic diacyl peroxides; dibasic acid peroxides; acetone peroxides; alkyl peroxyesters; alkyl hydroperoxides (for example, diacetyl peroxide); dibenzoylperoxide; bis-2,4-dichlorobenzoyl peroxide; di-tert-butyl peroxide; dicumulperoxide; tert-butylperbenzoate; tert-butylcumyl peroxide; 2,5-bis (t-butylperoxy) -2,5-d-methylhexane; 2,5-bis (t-butylperoxy) -2,5-dimethylhexino-3; 4,4,4 ', 4'-tetra- (t-butylperoxy) -2,2-dicyclohexylpropane; 1,4-bis- (t-butylperoxyisopropyl) -benzene; 1,1-bis- (t-butylperoxy) -3-3,5-trimethylcyclohexane; lauroyl peroxide; succinic acid peroxide; cyclohexanone peroxide; t-butyl peracetate; and butyl hydroperoxide. Suitable phenols are described in USP 4,31 1, 628, the disclosure of which is incorporated herein by reference. An example of an agent of a halogen phenolic cure product of condensation of a substituted phenol of halogen or a substituted phenol of C 1-10 alkyl with an aldehyde in an alkaline medium, or by condensation of the bifunctional phenoldialcohols. Suitable reaction products of amine aldehyde include ammonium formaldehyde; formaldehyde-ethylchloride-ammonium; acetaldehyde-ammonium; formaldehyde-aniline; butyraldehyde-aniline; and aniline-heptaldehyde. Suitable substituted ureas include trimethylthiourea; diethylthiourea; dibutylthiourea; tripentiltiourourea; 1,3-bis (2-benzothiazolylmercaptmethyl) urea; and N, N-diphenylthiourea. Suitable substituted guanidines include diphenylguanidine; di-o-tolylguanidine; diphenylguanidine phthalate; and the di-o-tolylguanidine salt of borate dicatecol. Suitable substituted xanthates include zinc ethylxanthate; sodium isopropylxantate; butylxanthatic disulfide; potassium isopropylxanthate; and zinc butylxanthate. Suitable dithiocarbamates include copper dimethyl, zinc dimethyl, tellurium dimethyl, dicyclohexyl cadmium, lead dimethyl, lead dimethyl, selenium dibutyl, zinc pentamethylene, zinc didecyl, and isopropyloctyl dithiocarbamate zinc. Suitable thiazoles include 2-mercaptobenzothiazole, mercaptothiazolyl mercaptide zinc, 2-benzothiazolyl-N, N-diethylthiocarbamyl sulfide, and 2,2'-dithiobis (benzothiazole). Suitable imidazoles include 2-mercaptoimidazoline and 2-mercapto-4,4,6-trimethyldihydropyrimidine. Suitable sulfenamides include N-butyl-2-benzothiazole-, N-cyclohexylbenzothiazole-, N, N-diisopropylbenzothiazole-, N- (2,6-dimethylmorpholino) -2-benzothiazole, and N, N-diethylbenzothiazole-sulfenamide. Suitable thiuramidisulfides include N, N'-diethyl-, tetrabutyl-, N, N'-diisopropyldioctyl-, tetramethyl-, N.N'-dicylohexyl-, and N.N'tetralauryl-thiuramidisulfide. Alternatively, the silane adhesion agents can be used. In this regard, any silane that will efficiently graft the polymers of this invention can be used. Suitable silanes include unsaturated silanes comprising an ethylene-unsaturated hydrocarbyl group, such as a vinyl, allyl, isopropenyl, butenyl, cyclohexenyl or α- (meth) acryloxy allyl group, and a hydrolyzable group, such as, for example, a hydrocarbyloxy, hydrocarbonyloxy, or hydrocarbylamino group. Examples of hydrolysable groups include methoxy, ethoxy, formyloxy, acetoxy, proprionyloxy, and alkyl to arylamino. Preferred silanes include unsaturated alkoxy silanes that can be grafted onto a polymer. These silanes and their method of preparation are described more fully in USP 5,266,627, the teachings of which are incorporated herein by reference. Vinyl trimethoxy silane (VTMOS), triethoxy vinyl silane, trimethoxy silane of γ- (meth) acryloxy and the mixture of these silanes are the preferred silane adhesion agents for use in this invention. The olefinic polymers can also contain up to 20 mol% of monomer units based on other non-aromatic, interpolymerizable monomers, such as a C.20 diene, preferably butadiene or 5-ethylidene-2-norbornene. The olefinic polymers can also be characterized by their degree of short or long chain branching (LCB or SCB) and the distribution thereof. Olefinic polymers such as traditional low density polyethylene LCB (LDPE) can be produced by a high pressure polymerization process using a free radical initiator. When used in the present composition, the LDPE normally has a density (p) <0.94 g / cc (ASTM D792) and a melt index (12) of 0.01 -100, preferably 0.1-50 g / 10 min (ASTM Test D, 1238, condition 1). Olefin polymers lacking LCB, such as polymers of linear low density polyethylene (heterogeneous LLDPE) or linear high density polyethylene (HDPE) polymers, typically result in a Ziegler polymerization process. USP 4,076,698 describes such a process. These olefinic polymers can also be referred to as "heterogeneous polymers". When used in the present invention, HDPE usually consists mainly of large linear polyethylene chains. HDPE has a p > 0.94 g / cc (ASTM-D1 505), and l2 (ASTM-1238, condition) of 0.01 - 100, and preferably 0.1 - 50 g / 10 min. The heterogeneous LLDPE generally has a p of 0.85-0.94 g / cc (ASTM D792), and a l2 (ASTM-1 238, condition 1) of 0.01-1.00, preferably 0.1 to 50 g / 10 min. Preferably, LLDPE has polymerized in the same ethylene and at least one C3-? Β, more preferably at least one C3.8, α-olefin. Preferred α-olefins include 1-butene, 4-methyl-1-pentene, 1 -hexene and 1-ketene. Other suitable olefinic polymers include those commonly referred to as homogeneous or uniformly branched polymers, an example of which is homogeneous LLDPE. The homogeneous polymers do not contain LCB and only have branches derived from the monomers (if they have more than two carbon atoms).

Homogeneous polymers include those made as described in USP 3,645,992, and those made using the so-called single-site catalysts in a chemical batch reactor having relatively high olefin concentrations (as described in USP 5,026,798 and USP 5,055,438). Uniformly branched, homogeneous polymers typically have a random comonomer distribution within a given interpolymer molecule and equal to the ethyl / comonomer ratios between the interpolymer molecules.

The suitable homogeneous LLDPE has a p of 0.85 - 0.94 g / cc (ASTM D 792), and a l2 (ASTM-1238, condition 1) of 0.01-100; and preferably 0.1-50 g / 10 min. The homogeneous LLDPE desirably results from the same monomers as heterogeneous LLDPE. A particularly suitable group of olefinic polymers is sometimes referred to as substantially linear ethylene / α-olefin polymers or substantially linear ethylene polymers (collectively referred to as "SLEP"). A SLEP has a processing similar to LDPE, but the strength and roughness of LLDPE. Like traditional homogeneous polymers, a SLEP has a unique maximum melting value, as opposed to Ziegler's heterogeneous polymerized ethylene / α-olefin interpolymers (EAO) having two or more maximum melting values (as determined using exploratory calorimetry). differential or DSC). USP 5,272,236 and USP 5,278,272, the teachings of which are incorporated herein by reference, describe the SLEPs and their preparation. The appropriate SLEPS have a p (ASTM D-792) of 0.85 g / cc - 0.97 g / cc, preferably 9.85 g / cc - 0.955 g / cc), and especially 0.85 g / cc - 0.92 g / cc. The SLEPS also have an I2 (ASTM D-1238, Condition 190 ° C / 2.16 kilogram (kg)) of 0.01 - 1000 g / 10 min., Preferably 0.01 - 100 g / 10 min, and especially 0.01 - 10 g / 10 min. Other suitable olefinic polymers include ultra low molecular weight ethylene polymers and EAO interpolymers described in the allowed U.S. Patent Application (serial number 09 / 359,486 filed July 22, 1,999) and its Patent Cooperation Treaty ( PCT) against part (WO 97/26287 published July 24, 1997), the teachings of which are incorporated herein by reference. These EAO interpolymers have a l2 > 1, 000 g / 10 min, or an Mn < 1 1, 000. A SLEP may be a homopolymer of a C2-C20 α-olefin, such as ethylene, propylene, or 4-methyl-1-pentene. It can also be an interpolymer of ethylene with at least one C3-C20 α-olefin, an acetylenically unsaturated C2-C20 monomer or a C4-C1 diolefin 8. A SLEP interpolymer can also be polymerized therein one or more other non-monomers saturated. Preferred olefin polymers suitable for use as component (B) include at least one of LDPE, HDPE, heterogeneous and homogeneous LLDPE, SLEP, polypropylene (PP), including isotactic polypropylene, hardened rubber and syndiotactic polypropylenes, or ethylene interpolymers -propylene (EP), chlorinated polymers such as CPE, ethylene-vinyl acetate (EVA) copolymers, and ethylene acrylic acid (EAA) copolymers. For EVA, EAA and CPE, the l2 (ASTM D-1238, Condition 190 ° C / 2.16 kg) is generally 0.01 - 1000 g / 1 0 min, preferably 0.01 - 100 g / 10 min, and especially 0.01 - 10 g / 10 minutes. Satisfactory PP has a melt flow rate or MFR (ASTM D-1238, Condition 230 ° C / 2.16 kg) of 0.01 - 1000 g / 10 min, preferably 0.01 - 100 g / 10 min, and especially 0.01 - 10 g / 10 minutes. Mixture Compositions In mixtures of components (A) and (B), Component (A) is presented in an amount > 5% by weight of the mixture, preferably > 15% by weight, and more preferably > 20% by weight, but preferably < 60% by weight, still more preferably < 55% by weight and more preferably < 50% by weight. All percentages are based on the combined weight of components (A) and (B). According to the above, the preferred amounts of component (B) simply equal the difference between 100% by weight and the amount of component (A). Using more than 60% by weight of component (A) in the polymer mixture will result in foam collapse, with the resulting product having a density greater than 250 kg / m3. Using less than 5% by weight of component (A) in the polymer blend will not result in a significant increase in open cell content or significant improvement in skin quality (ie, softness). The mixtures may be prepared by any means known in the art such as, for example, dry blending into a granulated form in desired proportions followed by dry blending in an apparatus such as a screw extruder press or a Banbury mixer. The dry-blended pellets can be melt processed directly into a final solid state article, for example, by injection molding. The mixtures can also be made by direct polymerization without isolating the components of the mixture. The direct polymerization can be used, for example, one or more catalysts in a single reactor or two or more reactors in series or in parallel and vary at least one of the operating conditions, monomer mixtures and choice of catalyst.

The polymer part of the foam of the invention can, if desired, contain < 30% by weight of a polymer unlike (A) or (B). However, the polymer part of the foam preferably consists of > 70% by weight of the components (A) and (B), based on the total weight of the polymers, more preferably > 90% by weight, and more preferably 100% by weight. In selecting the constituents of the polymer blend, polymer viscosity matching tends to improve mixing and minimize problems such as voids in a foam body or bubbling in a foam surface. This leads, in turn, to improved foam properties. The polymer blend compositions described above can be converted to foam products using any conventional process. The foam products include, for example, removed thermoplastic polymer foam, removed polymer filament foam, expandable thermoplastic foam beads, expanded thermoplastic foam beads, and fused thermoplastic foam beads. The products of the foam can be converted into articles manufactured using any conventional process or method. For example, any one or more expansion, melting and welding can be used in the manufacture of such articles, especially expandable foam beads. The foam products can take any physical configuration, such as extruded sheet, circle, bar, table, and configurations. One can also mold the expandable beads in any known configuration that employs the foam products, including, but not limited to, the following configurations. Conventional LDPE foam processes have a significant limitation in terms of a temperature range over which suitable foams can be made. That range is frequently no more than 1 ° C. The polymer blend foams of the present invention have a wider temperature range of 2-6 ° C. This is allowed for greater control in the selection of foam properties such as open cell content. The polymer foams of the present invention readily occur as a result of conventional foam preparation techniques. Using a conventional extrusion foaming process by way of example, one converts the components of the polymer blend to a polymer melt and incorporates a blowing agent into the polymer melt to form a foamable gel. One thus removes the foamable gel through a nozzle to form a desired product. Depending on the operating conditions and nozzle, the product may vary from a table or foam bar removed through a melt foam filament product, to make pearl foams and eventually cut filaments of foamable beads. Before removing the foamable gel through the nozzle, one typically cools the gel to an optimum temperature. To make a foam, the optimum temperature is typically above each vitreous transition temperature (Tg) of the polymer component, or by those having sufficient crystallinity to have a melting temperature (Tm), near Tm. "Near" means, above, or below and mostly depends on where the stable foam exists. The temperature desirably falls within 30 ° centigrade (° C) above or below the Tm. For the foams of the present invention, an optimum foaming temperature is in a range in which the foam does not collapse. The blowing agent can be incorporated or mixed into the polymer melt by any means known in the art such as with an extruder, mixer, or mixing machine. The blowing agent is mixed with the polymer melt at a high enough pressure to prevent substantial expansion of the melting polymer material and to generally disperse the blowing agent homogeneously therein., optionally, a nucleator can be mixed in the polymer melt or mixed dry with the polymer material before being plasticized or fused. The components (A) and (B) can be mixed dry and fed into an extruder funnel. The component (A) can also be added to an extruder after the component (B) is at least partially in a melting state. When added in this way, the component (A) can be part of a polymer concentrate which can include other additives or ingredients such as a pigment. In order to optimize the physical characteristics of the foam, one typically cools the foamable gel from a temperature that promotes melt mixing at a lower temperature before the gel passes through the nozzle. The gel can be cooled in the extruder or other mixing device or in separate chillers.

When making the removed foam, removed filament foam or foam beads, the cold, the foamable gel passes through a nozzle of desired shape (with an appropriate number of openings) and enters a zone of reduced or lower pressure promotes the foaming. The lower pressure zone is a lower pressure than that in which the foamable gel is maintained prior to extrusion through the nozzle. The lower pressure may be superatmospheric or subatmospheric (vacuum), but is preferably at an atmospheric level. The present foam structures can be formed into a filament form fused by extrusion of the compositions of the present invention through a multi-orifice nozzle. The trades are arranged in such a way that the contact between the adjacent currents of the molten extrudate occurs during the foaming process the contact surfaces adhere to each other with sufficient adhesion to result in the structure in unitary form. The molten extrudate streams coming out of the nozzle socket for the shape of filaments and nozzles, which desirably foam, collapse and adhere to each other to form a unitary structure. Desirably, the individual filaments or configurations removed should remain adhered in a unitary structure to prevent filament delamination under stresses found in the preparation, shaping, and utilizing the foam. USP 3,573, 12 and USP 4,824,720, the teachings of which are incorporated herein by reference, the apparatus described and the methods used in the fabrication of fused foam structure.

The foams of the present invention can also be made using an accumulator extrusion process and the apparatus such as that shown in USP 4,323,528 and USP 5,817,705, the teachings of which are incorporated herein by reference. This apparatus, commonly known as an "extruder accumulator system" that allows one to operate a process on a periodic basis, as opposed to continuous. The apparatus includes a maintenance zone or accumulator where the foamable gel remains under conditions that prevent foaming. The maintenance area is equipped with an external nozzle that opens in a lower pressure zone, such as the atmosphere. The nozzle has a hole that can be opened or closed, preferably in the manner of an inlet that is external to the maintenance area. The operation of the inlet does not affect the foamable composition as opposed to allowing it to flow through the nozzle. By opening the inlet and concurrently applying substantially the mechanical pressure in the gel by a mechanism (e.g., a mechanical ram) the gel is forced through the nozzle in a zone of lower pressure. The mechanical pressure is sufficient to force the foamable through the nozzle at a speed fast enough to avoid significant foaming within the nozzle yet still too slow to minimize and preferably eliminate the generation of irregularities in the area or transverse shape of the nozzle. the foam. As such, unlike operating intermittently, the process and its resulting products closely resemble those made in a continuous extrusion process. The present foam structures can also be formed into suitable foam beads to be molded into articles by expanding the pre-expanded beads containing a blowing agent. Pearls can be molded at the time of expansion to form articles in various ways. Processes for the production of expanded beads and molded expanded foam articles are described in Plástic Foams, Part II, Frisch and Saunders, p. 544-585, Marcel Dekker, Inc. (1973) and Plástic Materials, Brydson, 5th Ed., Pp. 426-429, Butterworths (1989). Expanded and expandable beads can be made by a batch or by an extrusion process. The discontinuous process of making expandable pearls is equal to the elaboration of expandable polystyrene (EPS). The granules of impregnated polymer mix, made by either melt or reactor mixture, with a blowing agent in an aqueous suspension or in an anhydrous state in a pressure vessel at a high temperature and pressure. Either the granules are discharged rapidly in a region of reduced pressure to expand the granules in the foam beads or to cool and discharge the granules as non-expanded beads. In a separate step, the unexpanded beads are heated to expand them, for example, with steam or hot air. The extrusion method is deduced with the conventional foam extrusion process described above to the mouth of the nozzle. The nozzle has multiple holes. In order to make non-foaming pearls, the foamable filaments are immediately annealed by removing the orifice from the nozzle in a cold water bath to prevent foaming and thus granulate the tempered filaments. Alternatively, the filaments are converted into foam beads by cutting the filaments into pellets or granules on the face of the nozzle and allowing the granules to expand. The foam beads can thus be molded by any means known in the art, such as loading the foam beads into the mold, compressing the mold to compress the beads, and heating the beads such as with steam to effect melting and welding. of the pearls to form the article. Optionally, the beads can be impregnated with air or other blowing agent at a high temperature and pressure before being loaded into the mold. In addition, the beads can be heated before being charged. The foam beads can thus be shaped into blocks or shaped articles by a suitable molding method known in the art. Some of the methods are taught in USP 3,504,068 and USP 3,953,558, both incorporated herein by reference. C. P. Park, supra. p. 191, pp. 197-198, and pp. 227-229, provides excellent teachings, incorporated herein by reference, of the above molding processes and methods. USP 4,379,859 and USP 4,464,484, the teachings of which are incorporated herein by reference, describe the preparation of foam beads. When the foam beads are made in place of the foam, first convert the blends used to prepare the foams of the present invention into discrete resin particles such as pellets of granulated resin. The particles are suspended in a liquid medium, such as water, where they are substantially insoluble and a blowing agent is thus introduced into the liquid medium. The use of high pressure and temperature in a pressure vessel such as an autoclave facilitates the impregnation of the particles with the blowing agent. The impregnated particles are quickly discharged from the pressure vessel in an atmosphere or a reduced pressure region to expand the particles into foam beads. A variation of the preceding extrusion process easily produces expandable thermoplastic polymer beads. The variation requires (a) cooling the foamable gel to a temperature lower than that at which foaming occurs, (b) removing the chilled gel through a nozzle containing one or more holes to form a corresponding number of expandable thermoplastic filaments. essentially continuous, and (c) granulating the expandable thermoplastic filaments to form the expandable thermoplastic beads. Any conventional blowing agent can be used to make foams of the present invention. Such conventional blowing agents fall into three generic classes: inorganic blowing agents, organic blowing agents and chemical blowing agents. Suitable inorganic blowing agents include nitrogen, sulfur hexafluoride (SF6), argon, water, air and helium. Organic blowing agents include (without limitation) carbon dioxide (CO2), aliphatic hydrocarbons C? -9, aliphatic alcohols C?, and C1-4 aliphatic hydrocarbons completely and partially halogenated. The aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, and the like. The aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. The full and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbons include methyl fluoride, perfluoromethane, ethyl fluoride, 1,1-difluoroethane (HFC-152a), fluoroethane (HFC-161), 1,1,1trif luoroethane (HFC-143a), 1, 1 , 1,2-tetrafluoroethane (HFC-134a), 1, 1,2,2-tetrafluoroethane (HFC-134), 1,1,1,3,3-pentafluoropropane, pentafluoroethane (HFC-125), difluoromethane (HFC-32) , perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Chlorocarbons and partially halogenated chlorofluorocarbons for use in this invention include methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), chlorodifluoromethane (HCFC-22), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123) and 1-chloro-1,2,2 , 2-tetrafluoroethane (HCFC-124). Fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichloro-trifluoroethane (CFC-113), dichlorotetrafluoroethane (CFC-114), chlorheptafluoropropane, and dichlorohexafluoropropane. Chemical blowing agents include azodicarbonamide, asodiisobutyronitrile, benzene sulfonhydrazide, 4,4-oxybenzenesulfonyl-semicarbazide, p-toluene sulfonyl semi-carbazide, barium azodicarboxylate, N, N'-dimethyl-N, N'-dinitroso-terephthalamide, trihydrazino triazine and mixtures of citric acid and sodium bicarbonate such as the various products sold under the name Hydrocerol ™ (a product of Boehringer Ingelheim). Any of the preceding blowing agents can be used alone or in combination with one or more blowing agents. The blowing agent or the blowing agent combination is present in an amount sufficient to convert the polymer melt into a foamable gel. The amount is desirably 0.2-5.0, preferably 0.5-3.0, and more preferably 0.7-2.5 gram-moles of blowing agent per kilogram of polymer present in the polymer melt. One can also add a nucleating agent to the foamable polymer or gel melt in order to control the foam cell size. Preferred nucleating agents include inorganic substances such as calcium carbonate, talc, clay, silica, barium stearate, diatomite, and mixtures of citric acid and sodium bicarbonate. Other nucleating agents conventionally used in the preparation of polymer foams can also be used. When used, the nucleating agent is present in an amount within a range of >0 to 5 parts by weight per hundred parts by weight of polymer (phr) present in the polymer melt. The range is preferably from > 0 to 3 phr. Various conventional additives can be incorporated in the foams of the present invention. The additives include, without limitation, inorganic filler pieces, conductive fillers, pigments, antioxidants, acid cleaner, flame retardants, ultraviolet absorbers, processing aids, extrusion aids, permeability modifiers, anti-static agents, and other thermoplastic polymers. The truth of the additives, such as inorganic and conductive filler pieces can also function as nucleating agents, promote the formation of open cells or both. Permeability modifiers (or stability control agents) can be added to the present foam to improve dimensional stability. Preferred agents include C10.2 fatty acid esters and esters. USP 3,644,230 and USP 4,214,054, the teachings of which are incorporated herein by reference, describe such agents. Monosterers can also reduce the static during and after foam making. Examples of the preferred agents include stearyl stearamide, glycerol monostearate, glycerol monobehenate, and sorbitol monostearate. When presented, such agents are used in an amount within a range of > 0 to 10 phr, based on the polymer in the foamable gel. By perforating the foams of the present invention, a gaseous permeability exchange is improved or accelerated wherein the blowing agent salts the foam and the air enters the foam. The resulting perforated foams have defined therein a multiplicity of channels that are preferably free of direction relative to the longitudinal extent of the foam. The channels extend from a foam surface at least partially through the foam, and sometimes completely through the foam from an external surface to another external surface. The channels desirably occur on substantially an entire external foam surface, preferably with uniform or substantially uniform spacing. Suitable spacing intervals can be up to and including 2.5 centimeters (cm), preferably up to and including 1 .3 cm. USP 5,424,016, USP 5,585,058, WO 92/19439 and WO 97/22455, the teachings of which are incorporated herein by reference, provide excellent information regarding perforation. If desired, the foams of this invention can be post-treated by any known means to increase the open cell content of foam. Such post-treatment methods include, without limitation, mechanically compressing the foam and expanding the foam by exposure to steam or hot air. The foams of the present invention exhibit excellent dimensional stability. Preferred foams retain > 80 percent of its initial volume when measured one month after an initial volume measurement within 30 seconds after expansion of the foam. The volume measurement can be used as any suitable method such as cubic displacement of water. The foams of the present invention are substantially free of degradation as indicated by a degraded gel content of < 10% based on the total weight of the foam or polymer (ASTM D-2765-84, Method A). While the degraded gel content is desirably as low as possible, the foam properties do not suffer from side effects of a very small amount of degradation, such as those occurring naturally without using degradation or radiation agents. The foams of the present invention have a p < 250, desirably < 150, preferably < 100, more preferably < 80 and more preferably 5-100 kg / m3 (according to ASTM D3575-93, index W, Method B). The foams have an average cell size of 0.05-10.0, desirably 0.1-5.0, and preferably 0.2-3.0 mm (mm) (ASTM D3576). The foams have an open cell content ranging from 0.01% vol. up to 99.9% vol. , depending on the selection of the component and the variations in the condition of the process. Foams with an open cell content of <20% vol. They usually fall into a class known as closed cell foams. Those known as open cell foams typically have an open cell content of > 20% vol, preferably > 25% vol., And more preferably > 30% vol. The open cell content is desirably < 100% vol, preferably < 95% vol. , and more preferably < 90% vol. (ASTM D2856-94), based on the total volume of the foam. The foams have a hardness of Inquiry C of < 80, desirably < 70, and preferably < 60. Hardness measurements of the foams using an Inquiridor C durometer for cellular rubber and sweet potato in accordance with ASTM D2240-97, but with a 5 mm diameter spherical penetrator. The foams of the invention desirably have a minimum cross-sectional area of > 1000 mm2, preferably > 1500 mm2, and more preferably > 2000 mm2. The "minimum cross-sectional area" refers to the smallest cross-sectional area of the foam. For example, a length of 50 mm x 20 mm in thickness x 3 meters (m) along the board-shaped foam has a minimum cross-sectional area of 1 000 mm2. If the foam is in the form of a sheet or board, it has a thickness that is > 1 mm, desirably > 3 mm, preferably > 5 mm, and more preferably > 7 mm It has a length that is desirably > 50 mm, preferably > 75 mm, and more preferably > 1000 mm As used herein, "thickness" of a foam board or sheet refers to its smallest transverse dimension (e.g., as measured from a flat surface to an opposite flat surface). When the foam is presented as a circle or bar, it has a diameter that is desirably > 40 mm, preferably > 50 mm, and preferably > 75 mm. The foam has an optimum drop test factor C (ASTM-D1596) of < 6, desirably < 5, and preferably < 4. The foams of the present invention can be used in any application where foams of comparable density and open or closed cell contents are used today. Such applications include, without limitation, pad packaging (e.g., corner blocks, brackets, holders, bags, envelopes, overwrapping, interleaving, encapsulation) of finished electronic products such as computers, televisions, and kitchen resources; packaging or protection of explosive materials or devices; material handling (warehouses, metal containers, box liner, metal container dividers and dividers, current diverter, packing, edges, part spacers and part separators); work station accessories (covers, table and bench top covers, rugs, seat cushions); automobile (titling, impact absorption in shock absorber or doors, carpet bituminous layer, insulation to the salor); flotation (eg, inflatable lifejackets and lifejackets); sports and selvage (for example, gymnastics and body boards); thermal insulation such as in such a way used a construction); laces, eyelets, seals; sound attenuation to be printers and machine writers; cabinet insertion; missile container liner; military projectiles; blocking and reinforcement of various transport issues; the preservation and packaging; car anti-noise pads, seals; medical devices, their skin contact pads; melted tablet; and vibration isolation pad. The preceding list merely illustrates a number of suitable applications. The skilled persons can easily imagine additional applications without departing from the scope or spirit of the present invention. The following examples illustrate, but do not in any way limit the scope of the present invention. The Arabic numerals illustrate the examples of the invention and the letters of the alphabet designate the comparative examples. All parts and percentages are by weight and all temperatures are ° C unless stated otherwise. Test Methods Use l2 (ASTM D-1238, condition 190 ° C / 2.16 kg (formally known as "condition (e)")) as a molecular weight indicator of the component of (A) SRIPs. It uses the proton nuclear magnetic resonance (1 H NMR) to determine the styrene SRIP content and the atactic polystyrene concentration (aPS). Prepare samples of proton NMR in 1, 1, 2, -2-tetrachloroethane-d2 (tce-d2) to produce solutions containing 1.6 - 3.2% by weight of polymer, based on the total weight of the solution. Use polymer l2 as a rigid guide in the determination of the sample concentration, with 3.2% by weight for a l2 >; 2 g / 10 min, 2.4% by weight for one l2 between 1.5 and 2. g / 10 min, and 1.6% by weight for one l2 < 1 5 g / 10 min. A suitable apparatus and associated operating conditions are a Varian vxr 300 with a sample specimen at 80 ° C, referenced to the residual protons of tce-d2 at 5.99 parts per million (ppm), scanning amplitude = 500 Hz, time of acquisition = 3,002 sec., pulse duration = 8 μsec, frequency = 300 MHz and delay = 1 sec. Use a polystyrene sample that has an Mw of 192,000 as a standard. Polymerization Method for Ethylene-Styrene Interpolymers (ESls) # 1 -3. 5-7 Using 1 -H-cyclopenta [1] phenanthrene-2-yl) dimethyl (t-butylamido) -silanetitanium, 1,4-diphenylbutadiene as a catalyst, prepare ESI's # 1 -3, 5-6 in a cycle continuously in operation (36.8 gallon (gal) 139 liters (L) capacity) equipped with an Ingersoll-Dresser pump with two propellers to mix. Run the complete reactor liquid at 475 psig (3,275 kilopascals (kPa)) with a residence time of approximately 25 minutes. Feed raw materials and catalyst / cocatalyst streams to the pump suction side through Kenics ™ static mixers and injectors. The pump discharge material in a 2"diameter line supplying two Chemineer-Kenics ™ 10-68 Type BEM series multi-tube heat exchangers (containing both the twisted strands to increase heat transfer). the output of the last exchanger, the cycle flow returns to the injectors and the static mixers next to the pump suction.Remove an output current from the cycle reactor between the two exchangers.Fuel the solvent in the reactor from two different sources Use a fresh stream of toluene to provide fast flow for the reactor to seal (20 Ib / hr (9.1 kg / hr) Mix the recycled solvent with non-inhibited styrene monomer on the suction side of five diagram pumps 8480- 5-E Pulsafeeder ™ connected in parallel to supply solvent and styrene to the reactor at 650 pounds per square inch of measurement (psig) (4.583 kPa). reactor at 687 psig (4,838 kPa). Introduce hydrogen into the ethylene stream and combine the ethylene / hydrogen mixture with the solvent / styrene stream at room temperature before entering the reactor. Cool the combined current to 2 ° C as the reactor cycle enters. Stop the polymerization by adding the catalyst death (water mixed with solvent) to the reactor product and thereby recover the product in the form of dry polymer pellets (<1000 ppm total volatiles). Polymerization Method for ESI # 4 Prepare ESI # 4 in a continuously stirred tank reactor Autoclave, coated with 6 gal. Oil. (CSTR) that exerts the complete liquid at 475 psig (3,275 Kpa). Supply toluene solvent to the reactor at 30 psig (207 kPa). Supply the uninhibited styrene monomer to the reactor at 30 psig (207 Kpa). Using an ethylene supply pressure of 600 psig (4, 137 kPa), prepare a combined stream as in the preparation of ESI # 1 -3, 5 and 6, but feed the reactor at a temperature of 5 ° C. Recover the polymer product in the form of dry polymer products in a manner equal to that used in the recovery of ESI # 1 -3, and 5-7. The various catalysts, cocatalysts and process conditions used to prepare the various individual ethylene styrene interpolymers (ESI # 1 -7) are summarized in Table 1 and their properties are summarized in Table 2. All samples used tris (pentafluorophenyl) ) borane (FAB) (CAS # 001 109-15-5) (Boulder Scientific) as a cocatalyst and a modified methylaluminoxane (MMAO) (CAS # 146905-79-5) (Akzo Nobel, MMAO-3A) as a cleanser. Unlike ESI-1, prepared with (t-butylamido) dimethyl (tetramethocyclopentadienyl) silane-titanium (II) 1,3-pentadiene as a catalyst, the entire ESI preparation used (1 H-cyclopenta [1] -phenanthrene) -2-yl) dimethyl (t-butylamido) -silanetitanium 1,4-diphenylbutadiene) as the middle catalyst. TABLE 1. CONDITIONS OF PREPARATION FOR ESI # 'S 1 -7 N / D = not available ESI # 8 and ESI # 9 are, respectively, ESI # 2 and ESI # 3 of Table 15 of WO 98/10015.

TABLE 2. PROPERTIES OF ESI # 'S 1 -7.

NM = not measured Additional Blend / Foam Components LDPE-1 = LDPE (l2 of 2.4 g / 10 min and p of 0.924 g / cm3). LDPE-2 = LDPE (l2 of 1.8 g / 10 min and p of 0.923 g / cm3). LDPE-3 = LDPE (l2 of 2.0 g / 10 min and p of 0.924 g / cm3). PP-1 = high melting strength PP (Montell PROFAX ™ PF814). PP-2 = PP homopolymer (Montell PROFAX ™ 6823). Antioxidant = IRGANOX ™ 1010 (Ciba). Nucleator = Talc or HIDROCEROL ™ CF40E (Boehringer Ingelheim).

Permeability modifier = glycol monostearate. Example (Ei) 1 and Comparative Examples (Comp Ex A and B) Using a foam apparatus comprising a single screw extruder press, mixer, coolers and foaming nozzle, prepare a foam product of the compositions shown in Table 3 at foaming temperatures shown in Table 3. All samples used HIDROCEROL ™ CF40E (Boehringer Ingelheim) as nucleator, 0.06 phr of IRGANOX * 1010 and unlike sample 1 e, which used none, 0.5 phr of glycerol monostearate , all amounts being based on 100 parts by weight of the total polymer weight. The resultant foams are submitted to the physical property test as shown in Table 3. The dimensions of the boards have a thickness range of 9-25 mm and a length range of 1 15-1 58 mm to provide a cross-sectional area > 1000 mm2. Make p, open cell content, cell size, compressive strength (at 25% compression), compression series measurements according to Nos. Of Test Method ASTM D3575-93 (index W, Method B ), D2856-94, D2856-94, D3573-93 (index B), and DIN 53572, respectively. Measure the dynamic cushioning factors C in accordance with ASTM D1596. Measure the compression recovery by compressing the foam by 90% of its original thickness, releasing the load and measuring the recovery after 24 hours. As shown by the data in Table 3, the foaming temperature window with PE / ESI mixtures is as wide as 4 ° C (for a specific composition), much larger than a typical 1 ° C or smaller foaming advantage for LDPE. It is also surprising that LDPE / ESI blends foaming at temperatures as high as 101 -1 10 ° C, since this temperature range is well above the Tg and crystalline melting temperatures of the ESI resins. Examples 1 a to 1 r show that the mixtures of the present invention readily provide stable foams with open cell contents ranging from 10 to 61 vol.%. This contrasts with the eliminated LDPE foams which typically have an upper open cell limit of 20% vol for stable foams. This follows from a drop of fast viscosity once the temperatures exceeded the LDPE crystalline melting points. The drop of viscosity leads, in turn, to foaming collapse after the nozzle. Examples 1 ba 1 e show that the use of ESI-3 in the blends with LDPE results in the significantly slower permeabilization of isobutane out of the foams, even though the glycerol monostearate is absent and the open cell content is as high as 26% vol (against Comp.Ex. A and B). This shows that the blends of the present invention provide dimensionally stable foams even in the absence of the permeability modifiers. The data in Table 3 show that the foams of the present invention have smaller cells than the reference foams made with LDPE (Ex Comp.A and B). The foams 1 e-1 i, 1 k-1 o and 1 q-1 r have significantly lower hardness than the LDPE foams of Comp. Ex. A and B. The improved softness and cellular structure, combined with more uniform skin (the last obtained with ESI-2 and 3, not ESI-1), are aesthetically more attractive and functionally desirable for soft touch, low abrasion applications such as the handling of automotive parts. Note that ESI-2 and ESI-3 have styrene copolymer contents greater than 15 mol%, while ESI-1 had a styrene copolymer content of 10.8 mol%. In addition, some LDPE / ESI blends (particularly those made with ESI-1 and ESI-3) result in damping (lower C factor) relative to foams made only from LDPE. Calculate the optimum C factor in the static load corresponding to the lowest G values using the formula: C = (G value x Foam Thickness) / (Drop Height) where the G value is determined according to ASTM D1596 at drip a foam charge after the foam has grown for 38 days at room temperature. or str = stress; NM = not measured Ei. 2 and Ei. Comp. C and D Repeat Ex. 1 with a large-scale extrusion line, using the process and formulation changes as shown in Table 4. Measure the percolation using ASTM D3573-93 (BB index). Table 4 The data in Table 4 show that the foams made from the blends of LDPE with ESI-7 (examples 2a and 2b) exhibit the following improvements over comparative foams C and D: more uniform skin, lower density in a fixed amount of the Blowing agent, reduced compression series and less compression percolation. Ei. 3: Polypropylene / ESI Mixtures Use a Haake mixing roller operating at 50 revolutions per minute (rpm) and a temperature of 190-200 ° C for 8 minutes to prepare fusion mixtures of PP and ESI resins. Conduct the fusion strength tests of the mixtures as well as pure PP, ESI and LDPE resins at 1 90 ° C. The tests include the tensile filaments of the fusion polymer at constant acceleration until tensile or rupture resonance occurs. The tests use a capillary galvanometer and a Rheotens device as the intake device. Record the force required to uniaxially extend the filaments as a function of the speed of capture. The maximum force achieved before the tensile or rupture resonance occurs equals the melting strength. Test conditions include a mass flow rate of 1.35 grams per minute, a temperature of 190 ° C, a capillary length of 2.1 mm, a piston diameter of 9.54 mm, a piston speed of 0.423 mm / second (mm / sec), a distance of traction down (exit of nozzle to the wheels of taking) of 100 mm, an acceleration of 2.4 mm / sec2, and cooling with ambient air. Table 5 summarizes the results of the test. The data shows that PP / ESI blends have improved melt extension (as measured by velocity) in relation to pure PP, and equal to that of pure LDPE and ESI (these two polymers are easier to foam than PP) . This should translate into improvements in the ability to make PP polymer foams.

Table 5 - Fusion Property Test Results EL 4 Using an extrusion foaming apparatus equal to that used in Example 1 and a filament foam nozzle, prepare the foam boards in a combined foam filament configuration of the compositions shown in Table 6 at the temperatures of foaming shown in Table 6. The compositions also include talc, calcium stearate and lrganox ™ 101 0, each at a loading of 0.6 phr per 100 parts by weight of the polymer blend, and 5.9 phr of isobutane as a blowing agent. . The nozzle has a plurality of 0.042 inches (1.07 mm) of openings spaced 0.144 inches (0.36 cm) apart. Table 6 also summarizes a number of foam properties (measured after growing for seven days at room temperature (nominally 23 ° C)). The data for cell size and compression strength represent an average of three additional values (length, and thickness). Measure the compression series (at 50% compression) according to the ASTM D3575-93 test.

Table 6 The data in Table 6 show that blends of PP-1 with ESI-5 and ESI-6 produce stable, low density foams with open cell contents ranging from 22 to 88 vol.%. The foaming temperature windows are as wide as 7 ° C. An increase in the content of ESI-5 and ESI-6 from 25% by weight to 50% by weight results in a lower compression strength (also known as compression deviation) and a reduced compression series. Lower values of compression strength also suggest softer foams. Ei. 5 and Ei. Comp. E and F Repeat Ex. 2 to prepare the blends of LDPE-2 and either ESI-8 and ESI-9 as shown in Table 7 using isobutane as a blowing agent at a concentration of 7.5 phr. Table 7 The data in Table 7 show that a high ESI content (greater than 60% by weight based on the combined weights of Components A and B) leads to foam collapse. Similar results follow from other blending compositions, blowing agents and additive combinations, all of which are described herein.

Claims (5)

1. CLAIMS 1. An open-cell polymer foam having a degraded gel content of not more than 10% percent, a minimum cross-sectional area of at least 1000 mm2, and a density of not more than 250 kilograms per cubic meter, whereby the least 70 per cent by weight of polymers in the foam comprises a mixture of: (A) from 5 to 60 weight percent, based on the combined weight of components (A) and (B), of at least one substantially random interpolymer which has a melt index of 0.05 to 1000 grams per 10 minutes, either a crystalline melting point or a glass transition temperature of about 80 ° C or less, whichever is appropriate, and which has: (1) from 8 to 65 percent mol of its monomer units derived from; (a) at least one vinyl or vinylidene aromatic monomer, or (b) at least one aliphatic or non-cycloaliphatic vinyl or vinylidene monomer sterically hindered. (C) a combination of at least one aromatic vinyl or vinylidene monomer and at least one aliphatic or cycloaliphatic vinylidene or vinylidene monomer sterically hindered. (2) from 35 to 92 percent mol of its monomer units derived from ethylene, an aliphatic α-olefin containing from 3 to 20 carbon atoms, or a mixture thereof; and having at least 80 mole percent of its monomer units derived from (1) and (2); and (B) from 95 to 40 weight percent, based on the combined weight of the components (A) and (B), of at least one polymer that does not have monomer units derived from (1) (a), (1) ) (b), or (1) (c), and at least 80 mole percent of its monomer units derived from monomers selected from ethylene, aliphatic α-olefins containing from 3 to 20 carbon atoms, and α-olefins aliphatics having from 3 to 20 carbon atoms and containing polar groups. The foam according to claim 1, characterized in that (A) has polymerized therein from 15 to 65 percent moles (1) and 85 to 35 percent moles (2), both percentages being based on the combined moles of (1) and (2) and giving a total of 100 mol percent. The foam according to claim 1 or claim 2, characterized in that (A) (1) is styrene, and (A) (2) is ethylene. The foam according to claim 1 or claim 2, characterized in that (B) is at least one homopolymer or ethylene copolymer having a density of less than 0.94 grams per cubic centimeter and a melt index of from 0.1 to 100 grams For 10 minutes. The foam according to claim 1 or claim 2, characterized in that (B) is at least one polypropylene homopolymer or polypropylene copolymer having a melt flow rate of from 0.01 to 100 grams per 10 minutes. The foam according to claim 1 or claim 2, characterized in that the component (B) additionally contains from 1-20 percent mol of monomer units derived from at least one ethylenically unsaturated polymerizable monomer unlike an α-olefin aliphatic that contains from 3 to 20 carbon atoms. 7. The foam according to claim 1 or claim 2, characterized in that component (A) additionally contains from 1-20 percent mol of polymer units derived from at least one ethylenically unsaturated polymerizable monomer unlike (A) (1) or (A) (2). 8. The foam according to claim 1, characterized in that the density is at least 5 kilograms per cubic meter. 9. The foam according to claim 4, characterized in that the component (A) has at least 27 mol percent of its monomeric units derived from styrene. The foam according to claim 1, characterized in that it further comprises at least one nucleating agent selected from calcium carbonate, talc, calcium stearate, zinc stearate, clay, silica, barium stearate, calcium stearate, zinc stearate, diatomite, citric acid, sodium bicarbonate, and mixtures thereof. eleven . The foam according to claim 1, characterized in that it also comprises at least one additive selected from inorganic filler pieces, pigments, antioxidants, acid cleaners, ultraviolet absorbers, flame retardants, processing aids, extrusion aids, permeability modifiers, agents anti-static, other thermoplastic polymers, and mixtures thereof. 12. The foam according to claim 1, characterized in that the foam has defined therein a multiplicity of channels, the channels being free of direction relative to the longitudinal extension of the foam and improving or accelerating u? gaseous permeability exchange where the blowing agent leaves the foam and the air enters the foam. The foam according to claim 1 or claim 2, characterized in that (B) is at least one polyethylene homopolymer having a density of less than 0.94 g / cc and a melt index of from 0.01 to 100 grams per 10. minutes, a polypropylene homopolymer, an ethylene-vinyl acetate copolymer, or an ethylene-acrylic acid copolymer. The foam according to claim 1 or claim 2, characterized in that the foam has a shape which is a board with a thickness of at least 20 millimeters and the length of at least 50 millimeters, a sheet with a thickness of at least 1 millimeter and length of at least 1000 millimeters or a bar that has a diameter of at least 40 millimeters. 15. The foam according to claim 1 or claim 2, characterized in that the foam is formed as thermoplastic foam beads or as expanded and fused thermoplastic foam beads and the expanded and fused thermoplastic foam beads or beads have an Inquiry C hardness of less than 80. 16. The foam according to claim 1 or claim 2, characterized in that the foam is a unitary foam structure which is a fused filament foam. 17. The foam according to claim 1 or claim 2, characterized in that the component (B) is a polypropylene that is modified by at least one adhesion agent. 18. The foam according to claim 17, characterized in that the adhesion agent is an azide compound. 19. A process for making the polymer foam of any of claims 1-19 comprising: (I) converting the mixture to a polymer melt; (II) introducing, at an elevated pressure, at least one blowing agent into the polymer melt to form a foamable gel, with the blowing agent occurring in a total amount of from 0.02 to 5.0 grams-moles per kilograms of polymers contained in the melt of polymer; (III) cooling the foamable gel to an optimum temperature; and (IV) removing the foamable gel from Step III through a nozzle in a lower pressure region to form a foam. The process according to claim 19, characterized in that the nozzle is a multi-orifice nozzle with sufficient orifice spacing to ensure that contact between the surfaces of the adjacent extrudate streams occurs during formation in the lower pressure region, the contact being sufficient to ensure that the contact surfaces adhere to each other with sufficient adhesion to result in a unitary foam structure which is a fused filament foam. twenty-one . The process according to claim 19, characterized in that steps (III) and (IV) constitute a discontinuous process that uses an accumulator extruder means to first accumulate the foamable gel in a maintenance zone maintained at a temperature and pressure that does not allow the gel foams and periodically expels the gel accumulated through the nozzle. 22. The process according to claim 19, characterized in that the optimum temperature is a temperature at which the foaming does not occur and the step (IV) is modified in such a way that the foaming does not occur and the resulting extrudate is granulated to form the beads Expandable thermoplastics. 23. A process for making the foam according to any of claims 1 -19 in the form of thermoplastic foam beads, which process comprises the sequential steps (I) - (V); (I) converting the mixture into a polymer melt; (II) cooling and granulating the polymer melt to form discrete resin particles; (lll) creating a suspension by dispersing the resin particles in a liquid medium in which they are substantially insoluble; (IV) introducing, at a high temperature and pressure, at least one blowing agent into the suspension to form the resin particles having a blowing agent incorporated therein, the blowing agent being present in a total amount of from 0.2 to 5.0 grams -moles per kilogram (based on the combined weight of polymers); and (V) rapidly discharging the product formed in Step IV in an atmosphere that promotes the conversion of the product into foam beads.