WO1996003460A1

WO1996003460A1 - Rigid vinyl polymers having improved processability

Info

Publication number: WO1996003460A1
Application number: PCT/US1995/008997
Authority: WO
Inventors: Robert Arthur Linder
Original assignee: Alliedsignal Inc.
Priority date: 1994-07-22
Filing date: 1995-07-18
Publication date: 1996-02-08

Abstract

The present invention provides an external lubricant composition for vinyl polymer. The external lubricant provides processing latitude and comprises an effective amount for lubricating the vinyl polymer of polyethylene having a Brookfield viscosity at a temperature of 140 °C of about 205 to about 345 centipoises and an acid number as determined by standardized titration of KOH of between about 5 and about 9. The rigid vinyl polymer compositions are useful in structural articles such as plastic pipe, siding, containers, and sheets.

Description

RIGID VINYL POLYMERS HAVING IMPROVED PROCESSABILITY

The present invention relates to external lubricant compositions for rigid vinyl polymers and more particularly, to external lubricant compositions for rigid polyvinyl chloride.

Background of the Invention

Rigid vinyl polymer compositions, such as polyvinyl chloride compositions, are utilized for producing a variety of structural articles such as plastic pipe, siding, containers, and sheets. These rigid compositions are substantially unplasticized.

In order to stabilize vinyl polymer against the decomposing influence of heat and light, tin compounds such as organotin mercaptides and organotin sulfides and basic lead compounds such as tribasic lead sulfate, dibasic lead phosphite, or dibasic lead phosphite sulfite are used. To enhance the effect of the lead compounds, typically metal soaps such as neutral or basic lead stearate and/or calcium stearate are added.

Lubricants are also added to vinyl polymers to facilitate the extrusion or other melt processing of the structural articles produced. Lubricants are generally classified as external or internal lubricants. An external lubricant provides a lubricating layer between the plastic melt and the metallic surfaces of the processing equipment. The external lubricant may coat the individual particles of the polymeric resin and inhibits their adherence to each other or fusion. In contrast, an internal lubricant reduces the effective melt viscosity of the vinyl polymer at the processing temperatures in order to improve its flow properties during processing and exhibits little adverse effect on fusion. An internal lubricant is generally needed only for thin extrusions such as films and thin-walled pipe or in complicated extrusions such as window or door linear profiles.

Known rigid polyvinyl chloride pipe formulations include compositions such as:

which is disclosed in TECHNICAL DATA FOR LOW

MOLECULAR WEIGHT POLYETHYLENES AND DERIVATIVES by AlliedSignal Inc., a chapter of the POLYMER ADDITIVE HANDBOOK (1992);

Rigid 4-Cell Resin 100 phr

Lead Stabilizer 5.0

Calcium Carbonate 1.5

Titanium Dioxide 2.0

Acrylic Processing Aid 3.0

Calcium Stearate 1.0

A-C^® 629A (oxidized O to 1 polyethylene wax, acid number of 16, Brookfield viscosity at

140°C of 200 centipoises) which is disclosed by David Hurwitz, "The Use of Low Molecular Weight Polyethylene in Rigid PVC Lubrication", Society of Plastics Engineers, 31 st Annual Technical Conference, 349 (May 1973); and

which is disclosed in A-C^® POLYETHYLENES FOR PVC by AlliedSignal Inc. (1986). See also Technical Data on A-C^® Polyethylenes and Copolymers for Plastics by AlliedSignal Inc. (1973) which teaches that A-C^® 629A (low density oxidized polyethylene wax with acid number of 16) is useful for lead stabilized polyvinyl chloride. Commonly assigned US Patent 4,218,353 teaches an external lubricant for PVC wherein the lubricant is a blend of α-olefin and oxidized low molecular weight polyethylene having an average molecular weight of less than about 5,000 and an acid number of about 10 to 35.

Additives which speed fusion in polyvinyl chloride compositions are desired in the art. ASTM D 2538 defines fusion time as the time from the point of loading the composition into the torque rheometer to the point of maximum torque. See also Robert A. Lindner, "External Lubricants that Speed Fusion", Plastics Compounding

(September/October 1989). The first and third formulations above are undesirable because the unoxidized homopolymer polyethylene wax having a Brookfield viscosity at 140°C of 180 or 200 centipoises delays fusion and thus, increases fusion time. Additionally, the unoxidized homopolymer polyethylene wax serves as more of a fusion control rather than an external lubricant and thus, it is necessary to add an additional external lubricant such as oxidized polyethylene wax having a Brookfield viscosity at 140°C of 200 centipoises or stearic acid to the composition. Although the first and third formulations above have good lubricity, the fusion times are too long. Additionally, stearic acid has a low melting point which means that it evaporates during normal processing conditions.

The second formulation above is undesirable because a processing aid is used which increases the cost of the final composition. Also, the presence of an acrylic processing aid in the final product may cause high viscosity and poor flow.

U.S. Patent 4,203,880 discloses tin stabilized polyvinyl chloride having a lubricant package comprising oxidized polyethylene wax and a known external lubricant such as paraffin oils, paraffin waxes, liquid and solid hydrocarbons, unoxidized polyethylene waxes, montan ester waxes, lead stearate, mineral oil, 12-hydroxystearic acid, and ethylene bis-stearamide and cites two articles which teach the preceding known external lubricants: lllmann, "Waxes as Lubricants in Plastics Processing", SPE Journal. 71 (June 1967) and King et al., "Characterization of Lubricants for Polyvinyl Chloride", Polvmer Engineering and Science 1 2(2). 1 12 (March 1972). The reference teaches that an oxidized polyethylene having a melt viscosity of 200 centipoises and an acid number of 16 undesirably increases fusion time.

Polyvinyl chloride systems which provide processing latitude are extremely attractive to polyvinyl chloride processors. Because the components of a polyvinyl chloride formulation and the weight percentages thereof are selected in order to provide desired final polyvinyl chloride properties, any system which allows a processor to vary the weight percentage of a component such as the external lubricant present without dramatically affecting processing conditions such as fusion time would be advantageous.

Thus, it would be desirable to have a vinyl polymer composition which has improved processing latitude, thermostability, and metal release. It would also be desirable to have a vinyl polymer composition which has improved plate-out resistance.

Summary of the Invention

We have found a composition which responds to the foregoing need in the art. Although U.S. Patent 4,203,880 teaches away from the use of lower molecular weight oxidized polyethylene, surprisingly, we have found that the weight percentage of lower molecular weight oxidized polyethylene having an acid number of between about 5 and about 9 may be varied without dramatically affecting processing conditions such as fusion time. The present compositions also have improved thermostability, metal release, and plate-out resistance.

The present external lubricant composition for stabilized vinyl polymer comprises: an effective amount for lubricating the vinyl polymer of polyethylene having a Brookfield viscosity at a temperature of 140°C of about 205 to about 345 centipoises and an acid number as determined by standardized titration of KOH of between about 5 and about 9.

The present invention also provides a composition comprising: (a) vinyl polymer; (b) an effective amount for stabilizing the vinyl polymer of stabilizer; and (c) an effective amount for lubricating the vinyl polymer of polyethylene having a Brookfield viscosity at a temperature of 140°C of about 205 to about 345 centipoises and an acid number as determined by standardized titration of KOH of between about 5 and about 9.

Other advantages of the present invention will be apparent from the following description and attached claims.

Detailed Description of the Preferred Embodiments

Vinyl polymers useful in the present invention include polyvinyl chloride and polymerized forms of vinyl acetate, vinyl chloride-vinyl acetate copolymers, vinylidene halides such as vinylidene chloride vinyl pyridine, vinyl carbazole styrene, vinylbenzene, acrylic esters such as methyl acrylate, ethyl acrylate, or methylmethacrylate as well as acrylonitrile. The preferred vinyl polymer is polyvinyl chloride which includes both homopolymers of vinyl chloride and both copolymers and terpolymers of vinyl chloride with comonomers such as vinyl acetate, vinyl formate, alkyl vinyl ethers, ethylene, propylene, butylene, vinylidene chloride, alkyl acrylates and methacrylates, alkyl maleates, and alkyl fumarates. Preferably, at least 80% and more preferably 100% of the monomer to be polymerized will be a vinyl chloride monomer. Vinyl polymers useful in the present invention are commercially available.

Stabilizers useful in the present invention include antimony thioglycolates and tin stabilizers such as organotin mercaptides, organotin sulfides, tin maleates, and tin thioglycolates such as butyltin thioglycolates and octylin thioglycolates. Tin stabilizers useful in the present invention are commercially available. Other useful tin stabilizers are disclosed in U.S. Patent 4,203,880 which is incorporated herein by reference.

Lead stabilizers useful in the present invention include tribasic lead sulfate, tetrabasic lead sulfate, dibasic lead phosphite, dibasic lead phosphite sulfite, and lead phthalate. The preferred lead stabilizer is tribasic lead sulfate. Lead stabilizers useful in the present invention are commercially available.

In order to enhance the effect of the lead or tin compounds, typically metal soaps such as metallic stearates are also added. Preferred metallic stearates include cadium stearate, manganese stearate, cesium stearate, lead stearate, lithium stearate, strontium stearate, sodium stearate, calcium stearate, barium stearate, and magnesium stearate. The more preferred metallic stearates are lead stearate, calcium stearate, and barium stearate. The most preferred metallic stearate is lead stearate. Metallic stearates useful in the present invention are commercially available.

An effective amount for stabilizing the vinyl polymer of the lead or tin stabilizer and metallic stearate is used. Typically, the lead or tin stabilizer and metallic stearate are present in an amount of about 0.25 to about 5 parts by weight per 100 parts of vinyl polymer. Typically, the ratio of lead or tin stabilizer to metallic stearate is about 1 :10 to about 10:1 .

The polyethylene of the present invention has a Brookfield viscosity at a temperature of 140°C of less than about 1000 and an acid number as determined by standardized titration of KOH of between about 5 and about 9. Suitable polyethylenes may be characterized as oxidized low density homopolymers of ethylene, copolymers containing acrylates and ethylene, terpolymers containing acrylates, esters, and ethylene. Preferably, oxidized low density homopolymers of ethylene are used. As indicated b the results for Examples 9 through 17 below, polyethylenes which have been oxidized to an acid number as determined by a standardized titration of KOH of preferably between about 6 and about 9 have minimal variation in fusion time as the weight percent of the polyethylene varies and also good stability and metal release properties and most preferably, to an acid number of about 7 to about 9. In another embodiment, polyethylenes which have been oxidized to an acid number as determined by a standardized titration of KOH of preferably between about 5 and about 6 have good plate-out resistance.

These polyethylenes have a density as determined by ASTM D-1505 preferably in the range of about 0.90 to about 0.94 and more preferably in the range of about 0.92 to about 0.93. These oxidized polyethylenes exhibit a Brookfield viscosity at a temperature of 140°C of preferably in the range of between about 240 and about 340 centipoises.

These oxidized polyethylenes as well as others which are useful in the practice of the present invention may be obtained by oxidizing polyethylenes with air or oxygen by conventional procedures. Suitable methods are described in U.S. Patents 3,060,163 and 3,322,71 1 which are incorporated herein by reference. As those skilled in the art know, the oxidation results in the scission of the polymer and the formation of acid groups. In addition to the formation of acid groups on the polymer chain, esters, aldehydes, ketones, hydroxides, and peroxides are also foun in various quantities along the polymer chains. If too little lubricant is present in the final vinyl polymer composition, the melt viscosity of the vinyl polymer composition may be too high or the fusion time may be too short. An extremely short fusion time is undesirable for extrudable compositions. To ensure fusion of a compound before it exits an extruder, elevated temperatures must be used which result in prolonged exposure of the polymer melt to elevated temperatures and leads to premature degradation. The polymer may stick to the metallic processing equipment and burn.

If too much lubricant is present in the final vinyl polymer composition, a condition referred to as "plate out" may occur. The excess lubricant rises to the surface of the vinyl polymer composition and remains in contact with the heated wall of the extruder, mill, or calendar roll for a sufficient time to become charred. The char is either carried along with the molten polymer causing discoloration, or the char may form deposits along the inner wall or in the die of an extruder, thereby altering the shape of the extruder article.

An effective amount for lubricating the vinyl polymer of oxidized polyethylene is used. Typically, the oxidized polyethylene is present in an amount of about 0.01 to about 5 parts by weight per 100 parts of vinyl polymer. The oxidized polyethylene is present preferably in an amount of about 0.05 to about 2 parts by weight per 100 parts of vinyl polymer, more preferably in an amount of about 0.05 to about 1 part by weight per 100 parts of vinyl polymer, and most preferably in an amount of about 0.1 to about 0.5 part by weight per 100 parts of vinyl polymer.

In addition to the heat stabilizer, metallic stearate, and external lubricant, the present compositions may contain one or more additives conventionally employed in moldable or extrudable polymer compositions. These additives include fillers such as alkaline earth metal carbonates, pigments such as titanium dioxide, antioxidants such as sterically hindered phenols or bis-phenols, impact modifiers such as methyl methacrylate-butadiene-styrene terpolymers, and adsorbents such as the alkaline earth metal silicates and diatomaceous earth if the composition contains a significant amount of liquid ingredients.

The vinyl compositions to which the present external lubricants are added are rigid which means that they contain essentially no plasticizer. Such vinyl resins are useful in the production of rigid articles, principally rigid pipe, siding, containers, and sheets.

It is known that the effectiveness of lubricants on resin formulations may be evaluated by measurement of rheological properties of the formulation. These properties are typically studied by means of a torque rheometer consisting of a miniature mixer and a torque meter which measure the load on the mixer. The mixing forces developed within a sample of material at a certain temperature cause a deflection of a recording dynamometer. This deflection is recorded on a strip chart. This torque, which is expressed in meter-grams, is directly related to the viscosity of the melt being mixed. When a polymer of the vinyl type degrades, it crosslinks rapidly and shows a sharp rise in its melt viscosity. The time for this to occur is a measure of the thermal stability under dynamic shear conditions. A typical torque rheometer curve provides one skilled in the art with information as to melting, fusion, flow, and crosslinking in the processing of the polymer tested. This procedure is set forth in ASTM D 2538-88 - "Standard Practice for Fusion of Poly(Vinyl ChlorideMPVC) Compounds Using a Torque Rheometer". The most generally used rheometer is the Brabender Plasticorder which essentially consists of an oil-heated roller mixing head driven by a variable speed motor equipped with means to measure the torque developed in the head. The machine is fitted with a mixing head equipped with a melt thermocouple. To determine the fusion time of a polyvinyl chloride powder blend, for example, an accurately weighed quantity of the blend is charged into the mixing head with the aid of a quick-loading chute. A graph of the torque against time is produced and the point when fusion is complete is shown by an initial peak in torque. The dynamic heat stability is measured in minutes from the start of the graph until the decomposition point which is marked by a rise in torque.

The present invention is more fully illustrated by the following non-limiting Examples. Unless otherwise stated, all parts are by weight.

COMPARATIVES AND EXAMPLES

U.S. Patent 4,203,880 teaches that increasing the amount of oxidized polyethylene from 0.1 to 0.8 parts by weight decreases fusion time and the results of Example 4 are reproduced below:

12

For a given melt viscosity, the difference between the maximum fusion time at 0.1 part by weight of oxidized polyethylene and the minimum fusion time at 0.8 part by weight of oxidized polyethylene is at least 2 minutes.

Robert A. Lindner, "External Lubricants that Speed Fusion", Plastics Compounding (1989) teaches that increasing the amount of oxidized polyethylene having an acid valve of 16 and viscosity of 200 centipoises from 0.1 5 to 0.75 parts per hundred decreases fusion time. The difference between the maximum fusion time at 0.15 parts per hundred of oxidized polyethylene and the minimum fusion time at 0.75 parts per hundred of oxidized polyethylene is 1 .6 minutes.

For each Example, the effect of the present external lubricants for polyvinyl chloride pipe compounds was determined utilizing a Brabender Plasticorder at 1 90°C jacket temperature, at 60 RPM, and sample size of 40xSPG. Each composition was prepared by blending in a Henschel mixer for 10 minutes at 3800 RPM and for an additional 10 minutes at 2600 RPM. The fusion time and fusion and equilibrium torque were determined from the plastogram and are recorded below. The stability measurements were done by Brabender Plasticorder. The present lubricants used had an acid number of 5.4 or 8.6 as determined by standardized titration of KOH.

The Comparatives were run in the same manner as the Examples except that the polyethylenes used had acid numbers outside of the range claimed for the present compositions.

For each Comparative and Example, the following materials were used:

MATERIAL CHEMICAL NAME SUPPLIER

Geon 103 EP F76 Polyvinyl Chloride Geon

T-137 Tin Thioglycolate Atochem Stabilizer

Acryloid KM 330 Acrylic Impact Rohm & Haas Modifier

Superflex 1000 Calcium Carbonate Pfizer Chemical Filler

Ca-St Calcium Stearate Synthetic Products External Lubricant

Titanox 2071 Titanium Dioxide NL Industries Pigment

Lubol 262 Fatty Ester Internal NL Industries Lubricant

For Comparatives A through H in Table I below, the polyethylene used had an acid number of 0. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 2.8 minutes.

For Comparatives I through P in Table 2 below, the polyethylene used had an acid number of 0.9. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 2.6 minutes.

For Comparatives Q through X in Table 3 below, the polyethylene used had an acid number of 3.4. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 1 .1 minutes.

For Examples 1 through 8 in Table 4 below, the polyethylene used had an acid number of 5.4. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 1 .1 minutes.

For Examples 9 through 16 in Table 5 below, the polyethylene used had an acid number of 8.6. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 0.4 minutes.

For Comparatives Y through FF in Table 6 below, the polyethylene used had an acid number of 16. The difference between the fusion time at 0.1 part per hundred of oxidized polyethylene and the fusion time at 0.75 part per hundred of oxidized polyethylene is 0.5 minutes.

TABLE 1

COMPARATIVE A B C D E F G H

103 EPF76 100 100 100 100 100 100 100 100

T-137 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

KM 330 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Superflex 100 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Ca-St 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Titanox 2071 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Lubol 262 1.5 1.4 1.25 1.0 0.75 -- 0.25 0

A-C® 6 0 0.1 0.25 0.5 0.75 1.25 1.5 Polyethylene (A.V.0)

Fusion Time 1.8 2.2 2.5 4.3 5.0 — 8.0 8.0 (minutes)

Fusion Torque 2200 2200 2050 1950 1950 — 1850 1700 (meter-gram)

Equilibrium 1900 1950 1950 1900 1950 1850 1800

Torq.

(meter-gram)

Stability: Fusion Time ~ 1.5 2.0 -- 3.5 - ~ (minutes)

Fusion Torque — 3050 2850 — 2350 — -- — (meter-gram)

Equilibrium 2150 2100 2000

Torq.

(meter-gram)

Stability Time — 21.1 21.1 32.8 -- -- — (minutes)

TABLE 2

| COMPARATIVE I J K L M N 0 P

103 EPF76 100 100 100 100 100 100 100 100

T-137 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

KM 330 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Superflex 100 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Ca-St 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Titanox 2071 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Lubol 262 1.5 1.4 1.25 1.0 0.75 — 0.25 0

Polyethylene 0 0.1 0.25 0.5 0.75 — 1.25 1.5 (A.V.0.9)

Fusion Time 1.8 2.0 2.6 4.2 4.6 ~ 5.4 4.2 (minutes)

Fusion Torque 2300 2250 2150 1850 1800 — 1600 1850 (meter-gram)

Equilibrium 2000 2000 1950 1850 1800 1600 1850

Torq.

(meter-gram)

Stability: Fusion Time - 1.5 1.8 - 2.9 ~ - (minutes)

Fusion Torque — 2950 2750 — 2300 ~ -- — (meter-gram)

Equilibrium 2050 1950 2000

Torq.

(meter-gram)

Stability Time — 17.0 17.9 — 23.9 — — (minutes) ^"

TABLE 3

TABLE 4

EXAMPLE 1 2 3 4 5 6 7 8

103 EPF76 100 100 100 100 100 100 100 100

T-137 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

KM 330 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Superflex 100 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Ca-St 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Titanox 2071 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0

Lubol 262 1.5 1.4 1.25 1.0 0.75 — 0.25 0

Polyethylene 0 0.1 0.25 0.5 0.75 — 1.25 1.5 (A.V.5.4)

Fusion Time 1.9 2.0 2.9 2.9 3.1 — 2.8 2.2 (minutes)

Fusion Torque 2400 2350 2300 2200 2100 — 2200 2200 (meter-grams)

Equilibrium 2000 2050 1950 1850 1800 1800 1800

Torq.

(meter-grams)

Stability: Fusion Time -- 1.3 1.7 ~ 2.3 - - - (minutes)

Fusion Torque ~ 3000 2800 ~ 2600 — — — (meter-grams)

Equilibrium 2050 1950 1950

Torq.

(meter-grams)

Stability Time ~ 17.5 18.3 — 26.5 -- -- — (minutes)

TABLE 5

EXAMPLE 9 10 11 12 13 14 15 16

103 EP F76 100 100 100 100 100 100 100 100

T-137 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

KM 330 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Superflex 100 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Ca-St 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

Titanox 2071 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.

Lubol 262 1.5 1.4 1.25 1.0 0.75 -- 0.25 0

Polyethylene 0 0.1 0.25 0.5 0.75 ~ 1.25 1.5 (A.V.8.6)

Fusion Time 1.3 2.1 2.0 2.0 2.5 ~ 1.9 1.6 (minutes)

Fusion Torque 2300 2350 2300 2250 2250 — 2300 2300 (meter-grams)

Equilibrium 2000 2050 2000 1900 1900 1900 1900

Torq.

(meter-grams)

Stability: Fusion Time -- 1.5 1.5 ~ 1.6 - - - (minutes)

Fusion Torque — 3000 2950 — 2800 — — ~ (meter-grams)

Equilibrium 2150 2000 1950

Torq.

(meter-grams)

Stability Time — 19.3 18.0 — 21.3 -- ~ — (minutes)

Comparing the stability time of Examples 10, 11, and 13 with Comparatives Z, AA, and CC, polyethylene having an acid number of 8.6 has improved stability.

TABLE 6

COMPARATIVE Y Z AA BB CC DD EE FF

103 EP F76 100 100 100 100 100 100 100 100

T-137 1 .5 1 .5 1 .5 1 .5 1 .5 1 .5 1 .5 1 .5

KM 330 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0

Superflex 100 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

Ca-St 1 .5 1.5 1.5 1.5 1 .5 1.5 1.5 1 .5

Titanox 2071 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.

Lubol 262 1 .5 1 .4 1 .25 1 .0 0.75 - 0.25 0

A-C® 629A 0 0.1 0.25 0.5 0.75 1 .25 1 .5 Polyethylene (A.V. = 16)

Fusion Time 1 .8 2.0 1 .7 1 .5 1 .5 — 1 .3 1 .2 (minutes)

Fusion Torque 2350 2350 2450 2500 2450 — 2600 2600 (meter-gram)

Equilibrium 2000 2000 2100 2200 2100 2150 21 50

Torq.

(meter-gram)

Stability: Fusion Time - 1 .3 1 .3 - 1 .1 - - -- (minutes)

Fusion Torque — 3100 3000 — 3100 ~ — — (meter-gram)

Equilibrium 2050 2050 2000

Torq.

(meter-gram)

Stability Time -- 16.7 16.8 — 17.0 — — — I (minutes)

For Comparatives GG through LL and Example 1 7, the compositions were prepared and evaluated as follows. The apparatus consisted of a two-roll mill. The back and front roll temperatures were 370°C. The back roll speed was 23 revolutions per minute while the front roll speed was 1 8.5 revolutions per minute. The mill gap was 40 mils.

Each composition was prepared in an intensive mixer and aged overnight. A 180 gram sample was then weighed, added to the mill, and allowed to band. When banding occurred, the block was started and excess compound not in the nip was taken off and discarded. Every 5 minutes, a sample was taken and mounted. Any excess cut off while taking the sample was returned to the mill and mixed in for 1 minute. When the compound bonded to the mill-roll surface, the test was terminated.

Each composition was then removed from the mill and discarded. The mill rolls were cleaned by adding stearic acid to the hot rolls which released most of the stuck compound. A silica-loaded cleaning compound was used to scour the rolls and it also absorbed the stearic acid in preparation for the next test. The results are indicated below. EBS is ethylene bis-stearamide.

TABLE 7

Claims

WHAT IS CLAIMED IS:

1 . A composition comprising: (a) vinyl polymer; (b) an effective amount for stabilizing said vinyl polymer of stabilizer; and

(c) an effective amount for lubricating said vinyl polymer of polyethylene having a Brookfield viscosity at a temperature of 140°C of about 205 to about 345 centipoises and an acid number as determined by standardized titration of KOH of between about 5 and about 9.

2. The composition of claim 1 wherein said vinyl polymer is polyvinyl chloride.

3. The composition of claim 1 wherein said polyethylene is present in an amount of about 0.01 to about 5 parts by weight per 100 parts of said vinyl polymer.

4. The composition of claim 1 wherein said polyethylene has a

Brookfield viscosity at a temperature of 140°C of between about 240 and about 340 centipoises.

5. The composition of claim 1 wherein said polyethylene has an acid number as determined by standardized titration of KOH of between about 5 and about 6.

6. The composition of claim 1 wherein said polyethylene has an acid number as determined by standardized titration of KOH of between about 7 and about 9.

7. The composition of claim 8 wherein said composition has improved plate-out resistance compared with a composition of vinyl polymer, stabilizer, and polyethylene having an acid number of less than 5 or greater than 9.

8. The composition of claim 9 wherein said composition has less variation in fusion time as the weight percentage of said polyethylene varies compared with a composition of vinyl polymer, stabilizer, and polyethylene having an acid number of less than 5 or greater than 9.

9. The composition of claim 9 wherein said composition has improved thermostability compared with a composition of vinyl polymer, stabilizer, and polyethylene having an acid number of less than 5 or greater than 9.

10. An external lubricant composition for a vinyl polymer wherein said external lubricant provides processing latitude, said external lubricant composition comprising: an effective amount for lubricating said vinyl polymer of polyethylene having a Brookfield viscosity at a temperature of 140°C of about 205 to about 345 centipoises and an acid number as determined by standardized titration of KOH of between about 5 and about 9.