MXPA99008094A - Method of reuse of waste of polyamide carpet and polyester mixed by the addition of a compatibilize - Google Patents

Abstract

Waste of mixed polyamide and polyester carpet can be recycled for use in the manufacture of new carpets and stacked fabrics by the addition of a copolymer derived from alkene monomer and a monomer containing unsaturated epoxy as a compatibilized agent.

Description

METHOD OF RETIREMENT OF CARBON WASTE OF POLYAMIDE AND POLYESTER MIXED BY THE ADDITION OF A COMPATIBILIZER BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to the recycling of mixed plastic waste to a mixture suitable for melt spinning of front carpet yarn. More particularly, the present invention relates to the mixing by melting of polyamide waste materials and carpet polyester into formulations suitable for the melt spinning of carpet threads with thread-like properties of this type made from virgin polyamides.

THE PREVIOUS TECHNIQUE During the last two decades, carpets for domestic and industrial use have increasingly been made from synthetic polymeric materials, and a major problem has arisen with the disposal of said floor coverings when they reach the end. of its useful life.

Disposal of such waste can be achieved in two ways: by burying them in a landfill site or by burning them in an incinerator facility. However, garbage sites are becoming increasingly scarce and expensive to use (in fact, many states now refuse to continue using valuable real estate in this way). Recent research has also suggested that garbage sites conveniently located near urban areas are implicated in health problems within local populations. The incineration of waste is also subject to much environmental disapproval, as well as by the public and in some scientific circles. Local pollution regulations are becoming increasingly stringent, and public attitudes are hardening against the use of this approach - the problem called "NIMBY" (not in my backyard). It should be noted, from a technical point of view, that the energy recovered from the incineration of waste plastics is low, particularly in terms of the volume of said scrap. In the vast majority of cases this approach will cost more money instead of winning one.

As humanity over the past few years becomes increasingly aware that petrochemicals (where the vast majority of polymers are based) represent a resource in finite diminution, the pressure on the plastics industry has increased. recycle the plastics used instead of trying to get rid of them. In Europe, and in some states of the United States, this practice is being enforced in the industry through legislation, although the difficulty in obtaining high-value final products, in particular, mixed polymer wastes is not fully appreciated. by the legislators.

Thus, the most favored option to deal with plastic waste is the recycling of these to other materials and / or products. As noted, however, the above is not a simple option. Regardless of the public perception of "plastic" as a single term to describe materials that are virtually identical, it is well known in the art that this is not the case, and that different types of plastics do not easily combine together to form a single material coherent. The reprocessing of streams of mixed plastic waste, without choice of types, or the addition of other materials, invariably results in materials of low final value. In many cases the cost of the equipment involved, and the energy consumed, can not be recovered in the sale of the product. To produce materials of value to the industry from recycled materials, one must apply great knowledge there must be particular waste streams of known and consistent content available.

Modern carpets usually consist of three main types of components: the frontal strand, which can be of any type of fiber, or mixtures thereof; the primary reinforcement (to which the strand is attached, or in which it is woven), which is usually a woven or nonwoven fabric of a polyester or polyolefin; and the secondary reinforcement (most of the construction weight), which may be an olefinic sheet or foam, an elastomeric material derived from a latex, etc., and which usually contains a high level of inorganic filler.

Several attempts have been made to recycle carpet scrap without prior separation of the components. JP 60 206 868 by Ikeda Bussan describes the spraying of discarded carpets, their mixing with ethylene-vinyl acetate in a proportion of approximately 50:50, and their classification to form a backing sheet for carpet use. The classification is carried out at low temperatures, so that the fiber component does not melt but on the contrary only disperses in the product. U.S. Patent No. 5,728,741 to Collins and Aikman presents a similar approach, although in this case the scrap is injection molded at high temperatures, prior to sorting, so that all the components are melted and mixed in. the molten state. Other patents relate to the recycling of scrap carpet without separating, but use maleated polyolefins and / or ethylene-vinyl acetate as compatibilizers. See, for example, JP 05 287 139 of Teijin; JP 05 293 828 of Toyota / Mitsubishi and US Pat. No. 5,719,198 of Lear Corporation. U.S. Patent No. 5,626,939 to Georgia Tech takes a low-energy approach by mixing scrap of well-shredded carpet with thermosetting resin precursors, and forming and trans-bonding the resultant blends into "synthetic wood".

None of the above processes results in a cast meltable product suitable for making fibers or strands.

Other inventors have sought to separate the scrap carpet components before recycling them as separate product streams. These mainly involve the cutting, detachment and granulation of the carpet followed by the separation of the various polymer components via cyclone, hydrocyclone or liquid flotation baths in varying density. See, for example, U.S. Patent No. 5,230,473 to Hagguist and Hume, U.S. Patent No. 5,518,188 to JPS Automotive, U.S. Patent No. 5,535,945 to BASF Corporation, U.S. Pat.

United States patent number 5,598,980 of Zimmer A.G. and the Patent in States United number 5,722,603 of Allied Signal / DSM. Dissolution methods have also been suggested, for example, 5,233,021 by Georgia Tech discloses the use of a supercritical liquid approach in which the variation of temperature and pressure is used to thereby dissolve the various components of the carpet scrap. Another alternative approach used for carpets containing PA6 is the direct recovery of caprolactam from carpet scrap as described in 5,169,870 of BASF Corporation and 5,668,277 of BSM.

The above separation processes are complex in many cases, involve a large number of stages, and obviously require the expenditure of funds in their implementation. It can also be noted that, in many of these approaches, only one product is obtained from the separation process and there is still the problem of discarding the other residues from the production process.

Focusing specifically on mixtures of polyesters and polyamides, a number of attempts have been made to manufacture products from them. U.S. Patent No. 5,565,158 to BASF Corporation discloses that fiber agglomerated scrap with PA / PET bicomponents can be spun into fibers without the need for compatibilizers. The above is a very specific system, and in any case it provides fibers which, while suitable for application in non-woven products, can not be used in the manufacture of front strands of carpets, due to their inappropriate physical properties.

Other mixtures of polyamides and polyesters that do include special compatibilizers have been presented in the past. U.S. Patent No. 4,150,674 of Mansanto refers to a ternary mixture of polyamide, polyester and a lactam terpolymer. The United States Patent Number 5, 055,509 of Allied Signal presents the use of phosphonyl aryl azides in this type of mixture. U.S. Patent No. 5,475,058 to Polyplastics / Diacel discloses a mixture of a polyester, a special polyamide with a carboxyl proportion to the amine end groups of at least 1.5 to 1, and a copolymer consisting of a glycidyl acrylate (meth) with one of styrenes, acrylonitrile or an alkyl acrylate. All these products and processes are directed to moldable resin blends and are not for use as fibers.

There is thus a need for a method for recycling polyester / polyamide blends, particularly for carpet scrap, which does not require complex component separation technology and results in a product that can be spun into fibers and threads with carpet grade. high final value.

SUMMARY OF THE INVENTION It has been found that the addition of an epoxy-modified olefin polymer to a mixture of polyamide and polyester recovered from carpet scrap results in a spinnable mixture from which yarn can be spun for carpet with identical use properties to those shown by the polyamide front strands of the original carpet.

DETAILED DESCRIPTION The present invention surprisingly allows the spinning of high quality carpet front strand fibers from blends of polyamides and polyesters present in carpet scrap.

Most polymer pairs, even those with seemingly similar structures, are not mixable. In a large number of cases the two phases do not interact in any way at all, and a fracture of such a sample sample will readily show that the different polymers are in self-contained regions with little or no interaction or adhesion between the phases. Even the use of compatibilizing additives (for a discussion of polymer-polymer compatibilization and the additives used as compatibilizers, see, LA Utracki, "Polymer Alloys and Mixtures", Hanser, Minich (1989), see also chapter on "Polymer Mixtures" in the Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition, Wiley, New York (1996), volume 19, page 837 et seq.) Tends to result only in reductions in interfacial tension between phases, and a decrease of dispersed domain size of the polymer that is the smallest component in the mixture. The complete thermodynamic miscibility between the polymer pairs is very rare, and it is even more rare to "force" such miscibility through the use of additives.

Most compatibilization processes and materials result in mixtures that, while suitable for injection or thermofixed molding applications, do not have the correct balance or properties, either in the molten state or in the solid, to be spun in fibers that would eventually find application in front strands of carpets.

In the course of the development work carried out in connection with the present invention it has been found that epoxy groups containing polyolefins, whether incorporated in addition to the copolymerization or by a grafting process to a (co) existing olefin polymer, have the effect of producing sufficient compatibilization of polyamide and polyester blends to allow these to be spun into negative carpet fibers. Said spinning can be carried out in standard fiber spinning machines and under conditions well within the normal parameters known to those skilled in the art. The fibers thus formed also have appropriate properties to enable them to undergo subsequent processes (eg, stretching, heat setting, texturing, bending, etc.) as is normally done in the manufacture of strand carpet front strands such as yarns. While not wishing to be limited to any particular mechanism, it is speculated that the combination of a polyolefin chain, which is poorly compatible with both phases of the mixture and will tend to congregate at the interfaces between the phases, together with side groups epoxies that are able to interact with both acidic and basic halves in the two phases of the mixture, resulting in a particularly strong but flexible compatibilization interaction.

Apart from the exemplary of this invention, the mixture of polymers to be recycled consists of at least one (co) polyamide and at least one (co) polyester. Examples of polyamides are thermoplastic fibers forming polyamides as exemplified by PA6, PA66, copolymers thereof and mixtures thereof. Examples of the polyesters are thermoplastic polyesters as exemplified by poly (ethylene terephthalate), poly (butylene terephthalate), copolymers thereof, poly (ethylene terephthalate-co-adipate), poly (trimethylene terephthalate) and mixtures thereof. The polyamide and polyester portions of the mixture may consist of one or more types of each of the polymer classes.

Preferably, the polyamide / polyester blend is derived from a combination of polyamide front strand and primary polyester backing material recovered from carpet scrap. The backing material recovered from carpet scrap can also be of the COLBACK type (COLBACK is a registered trademark of Akso which is a two component fiber sheath / core with PA6 as the sheath and PET as the core). The supply of carpet scrap can result from waste generated during any stage of the manufacture of strand or carpet or can be recovered from used carpets. The carpet formed entirely of scrap for use in the process of the invention will only require that the secondary backup be removed to prepare it for reprocessing. The removal of secondary backup can be achieved at a relatively low cost compared to the separation processes presented above, for example, by mechanical means, or by high pressure fluid abrasion. The "fraction" of carpet used in the practice of the present invention can then be cut, agglomerated and / or encapsulated before melted spinning. The recovered polymer mixture is treated in a form similar to polyamide for the spinning process, for example, it will be necessary to dry the raw material at moisture levels similar to those required in the spinning of polyamides, to prevent hydrolytic degradation of the fusion.

The carpet constructions will vary in the proportions of their various components, and this will affect the proportion of polyester with polyamide in the mixture to be mixed. The mixtures will contain between about 10% and about 25% by weight of polyester.

The compatibilizer used in the present invention consists of a copolymer formed from an alkene monomer, a comonomer with an epoxide functionalized side group, and optionally other comonomers. The epoxy group containing monomer is present at a level of about 1% to about 20% by weight, preferably about 5% to about 10%. Particularly preferred compatibilizers are ethylene glycidyl methacrylate copolymers as exemplified by Lotader AX8840 (Elf-Atochem North America Inc., Philadelphia). Said compatibilizers are included in the inventive formulation at a level of about 5% up to about 20% with respect to the total weight of the mixture. As an alternative, the epoxy functionality can be grafted onto a polyolefin.

The mixture of the invention may contain other additives in addition to the compatibilizer. Such additives may include dyes, antioxidants, UV stabilizers, antimicrobials, antistatic agents, flame retardants, fillers, nucleating agents, process aids, catalysts, improvements in the viscosity of the mixture, resistance to stains or dye modifiers or mixtures of the same.

Further teaching of the process of the invention is given in the following examples, which in no way should be considered as establishing any limitations to the appended claims.

EXAMPLES The following methods of thread spinning, texturing and padding were applied to the examples.

Strand Spinning Unrepeated strands were spun using a melt spinning extrusion system of a type and configuration known to those of skill in the art. The mixed molten polymer is filtered through a filter package containing a 50 x 250 mesh screen before being inserted into a 60-hole mold with trilobal-shaped recesses. The 60 filaments produced were separated into skeins of 2 x 30 filaments, finishing spinning was applied, and the two skeins were wound on separate reels to produce 1850 / 30Y thread without tensioning.

Strand Texturization Four ends of the 1850 / 30Y undrained strand produced were cotextured using mechanical stress texturing at a tension of 3.6 to give strands 2400 / 120Y.

Carpet Padding The BCF thread was cushioned in a carpet construction in 1/16 gauge cycles of 3/16 inch height and reinforced with a latex SBR backing, to give an approximate frontal weight of 20 ounces.

EXAMPLE 1 Natural resin PA6 of RV = 2.7 of water content of 550 ppm and 4.2 of a single black pigment dispersion at 25% was spun and textured under pressure to give a strand 2400 / 120Y. The BCF thread was cushioned on a carpet. The properties of the strand and carpet are illustrated in Table 1.

EXAMPLE 2 Strand of PA6 inked with color solution mixed with industrial material was cut into short lengths and dried before being melted back to its encapsulated form. A 325 mesh filter screen was used to filter the melt before encapsulation. The reencapsulated PA6 was dried at a moisture content of 550 ppm before being spun and textured under pressure to give a 2400 / 120Y BCF strand. The BCF thread was cushioned on carpet. The properties of the strands and carpet are illustrated in Table 1.

EXAMPLE 3 PA6 re-encapsulated as in Example 2 was cast fused with 15% backing of primary carpet with granulated copolyester and texturized by tension to strand 2400 / 120Y. The BCF thread was cushioned on carpet. The properties of the strand and carpet are illustrated in Table 1.

EXAMPLE 4 PA6 re-encapsulated as in Example 2 was cast fused with 15% backing of primary carpet with granulated copolyester and 10% of AX8440 Lotader from Elf Atochem, an epoxy modified polyolefin and textured by tension to give strand 2400 / 120Y. The BCF thread was cushioned on carpet. The properties of the strand and carpet are illustrated in Table 1.

EXAMPLE 5 A multi-color negative PA6 BCF 3450 strand was cushioned on a primary backing consisting of a copolyester without secondary backing or applied bond. The proportion of PA6 strand with the backing was approximately 85:15. The carpet thus formed was destroyed, dried and melted using 325 mesh filtration and then encapsulated. The encapsulated carpet was dried at 550 ppm moisture and then spun with a 4.2% addition of a 25% black single pigment dispersion, followed by stretch texturing to give a 2400 / 120Y strand. The BCF strand was re-cushioned in a 1 / 10th cycle carpet construction 3/16 inch in height and reinforced with a latex SBR backing to give an approximate 20-ounce frontal strand weight. The properties of the strand and carpet are illustrated in Table 1.

EXAMPLE 6 The encapsulated and dry carpet used in Example 5 was spun with an addition of 4.2% of a 25% black and 10% single pigment dispersion of AX8440 Lotader, followed by stress texturing to give a 2400/120 Y strand. The BCF thread was re-cushioned in a 1 / 10th cycle carpet construction 3/16 inch in height and reinforced with a latex SBR backing, to give an approximate 20-ounce frontal strand weight. The properties of the strand and carpet are illustrated in Table 1.

TEST PROCEDURES USED IN THE EXAMPLES Shrinking with hot air For a negative BCF 2400 thread, wind a skein of 8 turns using a negative wheel with a normal perimeter of 1125 m. Measure the length of the turn of the skein. Hang a 15 g weight from one end of the strand skein and place in an oven set at a temperature of 250 ° F (121 ° C). After two minutes, remove the skein from the oven and re-measure the length of the turn of the skein. Calculate the skein shrinkage as follows: Shrinkage (%) = 100 (A-B) / A where: A = original turn length of the skein, and B = final turn length of the skein.

Carpet Wear Test The padded carpet was tested by the ATSM D5252-92 test method at 50,000 revolutions at 70 ° F (21 ° C) and 50% RH. An Electrolux® vertical vacuum was used to vacuum the carpet after the test and before qualifying. The carpet was not vacuumed after every 2000 revolutions as detailed in the test method ASTM. The samples of used carpet were graded using the Reference Scale A of the Carpet and Rugs Institute, this scale consists of four photographs numbered from 1 to 4 showing the degrees of wear in gradual increase, deterioration of appearance or opaqueness. A grade of 1 indicates a very deteriorated sample. A grade of 5 indicates that no wear has occurred. If the test sample falls within two photographs, then a half degree is awarded. For example, if the degree of wear falls between photographs 3 and 4, then a grade of 3.5 is awarded. This test is known to those skilled in the art to simulate the trafficking of human feet. A revolution of the test drum is considered equivalent to a traffic of 8-12 feet.

TABLE 1 Properties of the Strand and Retention Data of Carpet Wear Although the examples of the invention have been described in detail, modifications thereto can be made and still fall within the scope of the appended claims.

Claims (16)

1. CLAIMS: 1. A method for producing a strand from waste fibrous materials suitable for the manufacture of carpets and stacked fabrics comprising the steps of: (a) chopping the waste fibrous materials to provide a mixture of short length material comprising 75-90% by weight of polyamide component and 10-25% by weight of polyester component; (b) adding from 5 to 20% by weight of a compatibilizing component to said mixture, said compatibilizing component consists of a copolymer derived from an alkene monomer and an unsaturated epoxy-containing monomer; and (c) subjecting said blend containing said compatibilizer component to a fiber spinning process by melt extrusion to form strands.
2. 2. A method according to Claim 1, wherein said polyamide component consists of PA6, PA66, copolymers of PA6 and PA66 or a mixture thereof.
3. 3. A method according to Claim 1, wherein said polyester component is selected from at least one of the group consisting of poly (ethylene terephthalate), poly (butylene terephthalate), copolymers thereof, poly (ethylene terephthalate-co-adipate) , poly (trimethylene terephthalate).
4. 4. A method according to Claim 1, wherein said compatibilizing component comprises an ethylene glycidyl methacrylate copolymer.
5. 5. A method according to Claim 1, wherein said scrap fibrous materials are derived from carpet scrap.
6. 6. A method according to Claim 1, which includes a step of adding an adjuvant.
7. 7. A method according to Claim 6, wherein said adjuvant is an antioxidant, stabilizer, dye, process aid, catalyst, filler, nucleating agent, antimicrobial, improvements in the viscosity of the mixture, resistance to stains or dye modifiers or mixtures of the same.
8. 8. A molten mixed fiber composition comprising a combination of: a) 75-90% by weight of polyamide component; b) 10-25% by weight of polyester component; and c) 5-20% by weight of a compatibilizing component consisting of a copolymer derived from an alkene monomer and an unsaturated epoxy-containing monomer, in which the polyamide and polyester components of said molten mixture consist of fibrous scrap materials .
9. 9. A fiber according to Claim 8, wherein said polyamide component consists of PA6, PA66, copolymers of PA6 and PA66 or a mixture thereof.
10. 10. A fiber according to Claim 8, wherein said polyester component is selected from at least one of the group consisting of poly (ethylene terephthalate), poly (butylene terephthalate), copolymers thereof, poly (ethylene terephthalate-co-adipate) , poly (trimethylene terephthalate).
11. 11. A fiber according to Claim 8, wherein said compatibilizing component consists of a copolymer of ethylene or glycidyl methacrylate.
12. 12. A fiber according to Claim 8, wherein said fibrous scrap materials are derived from carpet scrap.
13. 13. A fiber according to Claim 8, wherein said combination additionally contains an adjuvant.
14. 14. A fiber according to Claim 8 wherein said adjuvant is selected from the group consisting of an antioxidant, stabilizer, colorant, procedural aids, catalyst, filler, nucleating agent, antimicrobial, improvements in the viscosity of the mixture, resistance to stains or modifiers. of dye or mixtures thereof.
15. 15. A fiber according to Claim 8, wherein said fiber is a negative carpet fiber within the negative range of 500 to 7000.
16. 16. A carpet, stacked fabric or floor covering made using the fiber of Claim 15. EXTRACT OF THE INVENTION Waste of mixed polyamide and polyester carpet can be recycled for use in the manufacture of new carpets and stacked fabrics by the addition of a copolymer derived from alkene monomer and a monomer containing unsaturated epoxy as a compatibilizing agent.