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Polyvinyl chloride or polyolefin melt processable compositions containing polytetrafluoroethylene micropowder

a polytetrafluoroethylene and polyvinyl chloride technology, applied in the field of polyvinyl chloride or polyolefin melt processable compositions containing polytetrafluoroethylene micropowder, can solve the problems that ptfe cannot be fabricated by typical melt fabrication processes of extrusion and injection molding, severely limit the types of articles, etc., to achieve improved flame retardancy and/or low smoke generation, good oxygen index, and low peak hea

Inactive Publication Date: 2005-09-01
TEKNOR APEX
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006] Compositions of PTFE micropowder blended with either plasticized PVC or polyolefin are unexpectedly melt processable at relatively low temperatures and unexpectantly deform under shear as by elongation and thus can be mixed by utilizing conventional equipment such as a high shear mixer, a Banbury, a calender, and the like and articles can be made by extrusion, injection molding, compression molding, and the like. Such compositions have unexpected properties such as improved flame retardancy and / or low smoke generation, good oxygen index, low peak heat and total heat release, a low coefficient of friction, improved wear, abrasion, and chemical resistance, good processability in the molten state, and a reduction of dielectric properties. The PTFE micropowder containing compositions are generally free of a compatiblizing agent and can be utilized to make various end products such as food contact articles, medical products, thermoplastic articles having improved wear resistance and a low coefficient of friction, and insulation and / or jackets for wire or cable. The melt processing temperature of the PTFE blends is at a temperature significantly below the melting temperature of the PTFE micropowder.

Problems solved by technology

Conventional granular PTFE has an average or mean particle size of from about 20 to about 900 microns and is not melt processable due to its extremely high melt viscosity of at least 108 Pa.s at 380° C. Consequently, PTFE cannot be fabricated by typical melt fabrication processes of extruding and injection molding.
Other processes must be utilized such as compression molding and sintering which severely limit the types of articles which can be made.
However, such an extrusion process, known as paste extrusion, requires removal of the lubricant after extrusion.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0033]

TABLE 1ACompositions of Plasticized PVC) / PTFEThe PTFE micropowder was Dyneon PA5952 having a mean particlesize of about 6 microns and a peak melting temperature of 329° C.Example AExampleExampleExampleExampleExampleExample(Control)BCDEFGPVC, IV = 1.03100100100100100100100plasticizer30303030303030Lead stabilizer6666666Stearic Acid0.250.250.250.250.250.250.25Barium Stearate0.50.50.50.50.50.50.5Processing aid0.60.60.60.60.60.60.6FR - plasticizer 10000101010FR - plasticizer 25555555PTFE micropowder025507502550(6 Micron)

[0034]

TABLE 1BProperties of Plasticized PVC / PTFEExampleExampleExampleExampleExampleExampleExampleABCDEFGTensile strength, psi52004350345029004700385031002″ / min% elongation250230190170270240220Brittle point, ° C.−21.5−9.5−2−0.5−23−15−8Oxygen index2726.527.5282728.528Dielectric constant @ 12.932.822.742.682.952.862.81mega HzDissipation factor @ 10.0200.0310.0300.0290.0460.0410.042Mega HzPeak Heat Release Rate,41325123521850321193kw / m2Average Heat Release,2361701401252...

example 2

[0036] Example 2 relates to composition of plasticized PVC, PTFE micropowder, organic flame retardants, as well as generally inorganic flame retardants such as antimony trioxide, hydrated aluminum, and zinc borate.

TABLE 2ACompositions of PTFE / Plasticized PVC with the flame retardants andsmoke suppressantsExample BExample A(control)PVC, IV = 1.03100100plasticizer3030calcined kaolin55lead stabilizer66Stearic Acid0.250.25Barium Stearate0.50.5processing aid0.60.6FR - plasticizer 11515FR - plasticizer 255PTFE-PA 5952 (Dyneon)250antimony trioxide55Hydrated alumina4040smoke suppresant55Zinc borate22Total239.35214.35

[0037]

TABLE 2BProperties of PTFE / Plasticized PVC with the flame retardants and smokesuppressantsExample BExample A(Control)Tensile Strength, 2″ / min25003000% elongation220250Dielectric constant @ 1 mega Hz3.153.35Dissipation factor @ 1 Mega Hz0.04440.0285Oxygen Index4139Peak Heat Release Rate, kw / m2109114Total heat released, MJ / m248.6259.69Avg effective Heat of combustion, MJ / K...

example 3

PTFE Micropowder and LLDPE

[0039] In this Example, a set of compositions of LLDPE with different amount of PTFE micropowder was melt blended at 180° C. Table 3A sets forth the ingredients of the compositions whereas Table 3B sets forth the blend properties.

TABLE 3ACompositions of PTFE / LLDPEExample A(Control)Example BExample CExample DLLDPE100100100100PTFE0102550micropowder*

*Dyneon PA5956 having a mean particle size of about 2 microns and a peak melting temperature of 323° C.

[0040]

TABLE 3BProperties of PTFE / LLDPEExample AExampleExampleExample(Control)BCDCone @50 kw / m2flame out272288296335Peak heat2377180014901082release rate,kw / m2Avg heat1004890779645release rate,KW / m2Total heat212202185167released MJ / m2Avg heat of44383226combustion,MJ / KgArapahoe12.282.341.271.26smoke,Decharred %Arapahoe14.93.653.263.33Smoke, notdecharred, %% char19.8437.6561.3262.12tensileProperties% elongation918812709636tensile strength3059305521741729DC1k2.122.122.122.11DF1K0.000180.000220.000210.00021DC1M2.1...

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Abstract

The use of polytetrafluoroethylene micropowders having a particle size of generally less than about 20 microns as an additive for polyvinyl chloride or polyolefin unexpectedly produces compositions which are melt processable. Other unexpected properties include that the micropowder is deformable under shear and acts as a flame retardant.

Description

FIELD OF THE INVENTION [0001] The present invention relates to relatively low temperature melt processed compounded compositions of polytetrafluoroethylene (PTFE) micropowder with either a polyolefin or a polyvinyl chloride (PVC) and copolymers thereof. More specifically, the present invention relates to such compositions which have various desirable properties such as good flame retardantcy and / or smoke suppression, low heat release, an improved oxygen index, a reduced coefficient of friction, an improved wear, abrasion, and chemical resistance, and to articles made therefrom such as medical products, food contact articles, wire or cable insulation and / or jackets, and the like. BACKGROUND OF THE INVENTION [0002] Three major forms of PTFE exist: granular, fine powder and micropowder. Granular is produced by suspension polymerization in the absence of surfactant and generally is a spongy, porous irregular particle having a high molecular weight of about 10 million as obtained by rheo...

Claims

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Application Information

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IPC IPC(8): C08L23/08C08L27/06C08L27/18
CPCC08L27/06C08L27/18C08L2205/02C08L2666/04
Inventor LEE, BIING-LINPATEL, RAMANCOX, MARYELLENANDRIES, JOHN C.
Owner TEKNOR APEX
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