MXPA97000142A - Compositions of rigidas calandra vinyl polymer - Google Patents

Abstract

The present invention relates to: The present invention provides an external lubricating composition for the calendered vinyl polymer. The external lubricant provides rigid vinyl polymer compositions having improved slimming resistance, clarity, detachment and stability. The external lubricant comprises an effective amount for lubricating the polyethylene vinyl polymer having a Brookfield viscosity at a temperature of 150 ° C, greater than about 85,000 centipoises and an acid number as determined by the standardized KOH value of between about 5 and about 9. The sheets of the calendered vinyl polymer are used for blister packs and credit cards.

Description

"COMPOSITIONS OF CALIBRATED RIGID VINYL POLYMERS" The present invention relates to rigid calendered vinyl polymer compositions.

BACKGROUND OF THE INVENTION ^ __ Rigid vinyl polymer compositions, such as polyvinyl chloride compositions, are used to produce a variety of structural articles, such as plastic tubing, sills, containers and sheets. These rigid compositions are essentially not plasticized. The sheets are typically manufactured by calendering, which involves passing the material between rollers. Because the resulting sheets are typically used for blister packs and credit cards, a very clear end product is highly desirable. In order to stabilize the vinyl polymer against the influence of heat and light decomposition, tin stabilizer vinyl polymers including organotin stabilizers, such as organotin mercaptides and organotin sulfides are used to stabilize.

Lubricants are also added to the vinyl polymers to facilitate extrusion or other melt processing of the structural articles produced. Lubricants are generally classified as external or internal lubricants. An external lubricant provides a lubrication layer between the plastic melt and the metal surfaces of the processing equipment. The external lubricant is used to coat the particles "^. of the polymer resin and inhibits its adhesion to metal surfaces. In contrast, an internal lubricant reduces the viscosity by effective melting of the vinyl polymer at the processing temperatures in order to improve its flow properties during processing, as well as to activate its melting. An internal lubricant is generally needed only for thin extrusions, such as thin-walled films and pipes. The suitability of the lubricants for the vinyl polymer is determined by the type of stabilizer used in the vinyl polymer. For example, the PLASTICS ADDITIVE HANDBOOK, third edition (Hanser Publishers 1990) discloses that oxidized polyethylene waxes are suitable lubricants for tin-stabilized polyvinyl chloride sheets.

Known stable tin stabilized polyvinyl chloride calendered sheet formulations include compositions such as Rigid Resin of 4-Cells 100 phr Organotin Stabilizer 2.0 0 Acrylic Processing Assistant 3.0 to be known by David Hur itz "The Use of Low Molecular Weight Polyethylene in Rigid PVC Lubrication", 5 Society of Plastic Engineers, Annual Technical Conference Trigesimoprimera, 349 (May 1973), and PVC 100 phr 0, * '*' - Processing Assistant 1.5 Glycerol mono-oleate 1.0 Octyl Stabilizer Sn 1.6 5 Impact or Shock Modifier 5 - 10 A-c'R) 316 (oxidized homopolymer polyethylene wax, number 0 of acid of 16) 0.05-0.3 J which is disclosed in A-C < R) POLYETHYLENES FOR PVC by AlliedSignal Inc. (1986). See also Technical Data on Ac (R) Polyethylenes and Copolymers for Plastics by AlliedSignal Inc. (1973) which gives 5 that -c (R) 392A (high density oxidized polyethylene wax having an acid number of 30). ) is useful for tin-stabilized polyvinyl chloride. See also Technical Data on -c (R) Polyethylenes for c- Plastics by Allied (1984) which discloses that -c (R) 0 316A (high density oxidized polyethylene wax having an acid number of 16) or -c (R) 330 (high density oxidized polyethylene wax having an acid number of 30) is useful for tin-stabilized calendered polyvinyl chloride. US Pat. No. 4,203,880 discloses tin stabilized polyvinyl chloride having a lubricant package comprising oxidized polyethylene wax having an acid number greater than 5., and a melt viscosity of 1,000 to 60,000 centipoise 0 to 140 ° C, and a known external lubricant such as paraffin oils, paraffin waxes, liquid and solid hydrocarbons, non-oxidized polyethylene waxes, ester of montane ester, stearate of lead, mineral oil, 12-hydroxystearic acid, ethylene bis-stearamide and glycol esters of fatty acids containing from 10 to 20 or more carbon atoms. It would be desirable for there to be a calendered vinyl polymer composition having improved resistance to thinning, clarity, detachment, stability and improved slimming strength compared to the calendered vinyl polymer compositions currently used.

COMPENDIUM OF THE INVENTION A composition has been found that meets the need previously cited in the art. Surprisingly, we have found an external lubricant composition for vinyl polymer, wherein the external lubricant provides resistance to improved electrodeposition, clarity, detachment and stability. In this manner, the present invention provides a composition comprising: (a) vinyl polymer; (b) an amount effective to stabilize the vinyl polymer of the tin stabilizer and (c) an amount effective to lubricate the polyethylene vinyl polymer having a Brookfield viscosity at a temperature of 140 ° C, greater than about 85,000 centipoise and an acid number as determined by the normalized KOH titration of between about 5 and about 9. If measured at a temperature of 150 ° C, the polyethylene has a Brookfield viscosity of about 40,000 to about 60,000 centipoise. The present invention also provides a calendered sheet comprising: (a) vinyl polymer; (b) an amount effective to stabilize the vinyl polymer of the tin stabilizer and (c) an effective amount for lubricating the polyethylene vinyl polymer having a Brookfield viscosity at a temperature of 140 ° C, greater than about 85,000 centipoise, and an acid number as determined by normalized KOH titration of between about 5 and about 9. The present composition and the calendered sheets made of the present composition advantageously have improved resistance to thinning and light transmission compared to the known composition. which has an external lubricant of pentaerythritol adipate stearate. Other advantages of the present invention will become apparent from the following description and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES 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 vinyl pyridine, vinyl carbazole styrene, vinylbenzene, acrylic esters such as methyl acrylate, ethyl acrylate or methyl methacrylate as well as acrylonitrile. The preferred vinyl polymer is a polyvinyl chloride which includes both vinyl chloride homopolymers and both copolymers and terpolymers of vinyl chloride with comonomers such as vinyl acetate, vinyl formate, alkylvinyl ethers, ethylene, propylene, butylene, chloride of vinylidene, alkyl acrylates and methacrylates, alkyl maleates and alkyl fumarates. Preferably, at least 80 percent and most preferably 100 percent of the monomer to be polymerized will be a vinyl chloride monomer. The vinyl polymers useful in the present invention can be obtained commercially. Stabilizers useful in the present invention include cadmium, barium, zinc and calcium salts; and tin stabilizers, such as tin maleate and tin thioglycollates. Stabilizers of tin are preferred. A particularly preferred tin stabilizer is ethyl thioglycolate. The tin stabilizers useful in the present invention can be obtained commercially. Other useful tin stabilizers are disclosed in U.S. Patent Number 4,203,880 which is incorporated herein by reference. '-. An effective amount is used to stabilize the vinyl polymer of the tin stabilizer. Typically, the tin stabilizer is present in an amount of about 0.25 to about 5 parts by weight per 100 parts of the vinyl polymer. The polyethylene of the present invention has a Brookfield viscosity at a temperature of 140 ° C greater than about 85, 000 centipoise and an acid number as determined by normalized KOH titration of between about 5 and about 9. If measured at a temperature of 150 ° C, the polyethylene has a Brookfield viscosity of about 40,000 to about 60,000 centipoise. Suitable polyethylenes can be characterized as high density oxidized homopolymers of ethylene, copolymers containing acrylates and ethylene, terpolymers containing acrylates, esters and ethylene. Preferably, oxidized high density ethylene homopolymers are used. These polyethylenes have been oxidized to an acid number as determined by a more preferred normalized KOH titration, of between about 1 and about 12, and especially preferably between about 5 and about 9. The appropriate oxidized polyethylenes can be obtained from AlliedSignal Inc. of Morristown, New Jersey. A preferred oxidized polyethylene is listed in the following Table: Polyethylene Number of Acid Density Oxidized Viscosity (mgKOH / gram) (gr / cc) Brookfield (cps at 140 ° C) A-C (R> 307A 5 - 9 0.98> 85,000 These oxidized polyethylenes as well as others which are useful in the practice of the present invention can be obtained by oxidizing the polyethylene with air or oxygen by conventional methods. Appropriate methods are described in U.S. Patent Nos. 3,060,163 and 3,322,711 which are incorporated herein by reference. As is known to those skilled in the art, oxidation results in cleavage of the polymer and formation of acid groups. In addition, from the formation of acid groups in the polymer chain, the esters, aldehydes, ketones, hydroxides and peroxides are also found in different amounts along the polymer chains. If too small a quantity of lubricant is present in the final vinyl polymer composition, the melt viscosity of the vinyl polymer composition may be too high or the melting time may be too short. An extremely short melting time is undesirable for extrudable compositions because this can result in prolonged exposure of the polymer melt at elevated temperatures resulting in premature degradation. If too large a quantity of lubricant is present in the final vinyl polymer composition, a condition referred to as "SLIMMING" may occur. The excess lubricant rises to the surface of the vinyl polymer composition and remains in contact. with the heated wall of the extrusion apparatus, the mill or the calender cylinder for a period of time sufficient to singe. The singeing is carried out either together with the molten polymer, causing discoloration or scorching can form deposits along the inner wall or in the die of the extrusion apparatus thereby altering the shape of the extruded or calendered article. An effective amount is used to lubricate the vinyl polymer of the oxidized polyethylene. Typically, the oxidized polyethylene is present in an amount of about 0.01 to about 10 parts by weight per 100 parts of vinyl polymer. The oxidized polyethylene is preferably present in an amount of about 0.05 to about 5 parts by weight per 100 parts of the vinyl polymer, more preferably in an amount of about 0.05 to about 1 part by weight per 100 parts of the vinyl polymer, and especially preferably in an amount of about 0.1 to about 1 part by weight per 100 parts of the vinyl polymer. In addition to the thermal stabilizer and the external lubricant, the present compositions may contain one or more additives that are conventionally employed in the polymer compositions. These additives include fillers or fillers, such as alkaline earth metal carbonates, pigments such as titanium dioxide, antioxidants such as sterically hindered phenols or bis-phenols, impact or shock modifiers such as methyl methacrylate-butadiene-styrene terpolymers , and adsorbents such as alkaline earth metal silicates and diatomaceous earth, if the composition contains a significant amount of liquid ingredients. The vinyl compositions to which the external lubricants present are added are rigid which means that they contain essentially no plasticizer. These vinyl resins are useful in the production of rigid articles, mainly pipes. rigid, costaneras, containers and sheets. It is known that the effectiveness of lubricants in resin formulations can be evaluated by measuring the rheological properties of the formulation. These properties are typically studied by means of a torque rheometer of torsion consisting of a miniature mixer and a torque meter that measures the load on the mixer. The mixing forces developed within a sample of material at a certain temperature, cause a deviation of a record dynamometer. This 0 deviation is recorded in a strip chart. This torque, which is expressed in meter-grams, is directly related to the viscosity of the fusion that is being mixed. When a vinyl-type polymer is degraded, it rapidly cross-links and exhibits a sharp elevation in its melt viscosity. The time for this to occur is a measure of the thermal stability under dynamic shear conditions. A curve of the typical torque rheometer provides a person skilled in the art with information regarding melting, melting, flow and crosslinking in the processing of the tested polymer. This procedure is disclosed in Method D 2538-88 of the American Society for the Testing of Materials "Standard Practice for Fusion of Poly (Vinyl Chioride) (PVC) Compounds Using a Torque Rheometer". The most general used rheometer is the "Plasticorder Brabender" 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 conditioned with a mixing head equipped with a thermoelectric melting tank. To determine the melting time of the vinyl chloride powder mixture, for example, an exactly weighed quantity of the mixture is charged to the mixing head with the aid of a fast-charging chute. A graph of the torque versus time is produced and the point where the fusion is completed is shown by an initial maximum in torque. The dynamic thermal stability is measured in minutes from the beginning of the graph to the point of decomposition that is marked by an elevation in the torque. The present invention is illustrated more fully by the following non-limiting Examples. Unless otherwise stated, all parts are by weight.

EXAMPLES OF COMPARISON AND EXAMPLES For each Example, the effect of the external lubricants present for the calendered polyvinyl chloride sheet composites was determined using a "Plasticorder Brabender" at a temperature of 190 ° C, at 60 revolutions per minute and a sample size of 40xSPG. Each composition was prepared by mixing in a Henschel mixer for 10 minutes at 3,800 revolutions per minute and for an additional 10 minutes at 2,600 revolutions per minute. The light transmission was measured by spectrophotometry using a "Coloreye Macbeth" 3000. The injection molded samples of the clear rigid polyvinyl chloride with the following dimensions were those that were used (3.81 x 2.54 x .381 centimeters). The transmittance was terminated using a light source D65 that is representative of daylight from the northeast end and a standard observer of 10 °. CIELAB was the calculation method for the amount of light transmission through each sample. Glass was used as the norm. The spiral flow was measured using the following equipment. The injection molding machine was Kawaguchi K25C (28 grams, type of reciprocating screw). The mold was made to measure, with multiple cavities for the thermoplastic products. The cavity was 6.35 millimeters, in a semi-round spiral, four turns, a maximum radius of 3.81 centimeters, five millimeter marks filled from the shore. The injection molding parameters were normal rigid PVC conditions. The procedure was an injection mold of one to two dozen coils, which determine the final lengths and select the median value. The two-row mill tack test determined the time required for the external lubricant system of the composite to disintegrate and thereby cause the compound to adhere to the metal surfaces of the mill. The mill was installed under the conditions indicated below. 180 grams of each compound were used. The test procedure was as follows: (1) The mill rolls were cleaned using stearic acid. (2) The mill was left running for 10 minutes to allow the temperature to equilibrate. (3) The compound was added between the point of attachment of the cylinders until it was banded, that is, adhered to the cylindricals. (4) The time for the banded was noted. (5) Using a brass knife and alternating from left to right, the banded blade was cut and folded 12 times. (6) After 5 minutes, the sheet was removed from the cylinders and wound up through the fastening point. (7) Steps 5 to 8 were repeated until the sheet could no longer be removed from the cylinders. This time was noted and designated as the time of adhesion. The present lubricant used was A-c (R) 307A, oxidized polyethylene which can be obtained commercially from AlliedSignal Inc. of Morristown, New Jersey, United States of America. The properties of this oxidized polyethylene are the following: Polyethylene Number of Acid Density Oxidized Viscosity (mgKOH / gram) (gr / cc) Brookkfield! Cps at 140 ° C) A-C < R) 307A 5 - 9 0.98 > 85,000 The Comparison Examples were carried out in the same manner as the examples, with the exception that the external lubricants used at present were used instead of the external lubricants present. For each example of comparison and example, the resin used was Shintech 650 PVC resin, K56-58 and the used modifier was Kanace B22 which is MBS. The tin stabilizers used were Thermolite 83 which is octyltin thioglycolate and Thermolite 890 which is octyltin thioglycolate. The internal lubricant was , -_, Loxiol G16 which is a glycerol ester or Lubol 515 which is 0 a glycerol ester. The external lubricant used was Loxiol G70S which is pentaerythritol adipate stearate or A-C (R) 316, high density oxidized polyethylene wax having an acid number of 16 and a viscosity Brookfield of 8,500 centipoises that is measured at 140 ° C. 5 EXAMPLE OF COMPARISON A AND EXAMPLE 1 > - > '' - COMPONENT COMP. EXAMPLE 1 0 PVC 100 100 Modifier 5.00 5.00 Thermolite 831 1.25 1.25 5 Thermolite 890 1.25 1.25 Loxiol G16 or Lubol 516 0. 75 0. 875 Loxiol G70S 0.25 Polyethylene A-C < R) 307 0.125 Brabender Fusion Test (165 ° C, 30 RPM, 54gr): Melting Time (min) 1.3 1.2 Maximum Torque Torque (meter-grams) 3,200 2,800 Torque of Balance (meter-grams) 2,075 2,100 Brabender stability (190 ° C, 60 RPM, 54 gr): Stability time (min) 29 38 Maximum Torque Torque (meter-grams) 3,400 3,300 Torque of Balance (meter-gram) 1,150 1,200 Fusion Time (min) 0.3 0.3 Spiral Flow (cm) 54 53 Transmittance of Light 88.98 93.43 Two Cylinder Mill Grinding Test: Time to Adhesion (min) 20 60 172 ° C / 163 ° C / 23 RPM Mill 15 Adhered Non-adhesion Thinning Observation None None EXAMPLES OF COMPARISON B TO I AND EXAMPLES 2 TO 4 For Comparison Examples B to I and Examples 2 to 4, the type and amount of external lubricant was varied. The other components indicated in the following table remained the same: PVC 100 PHR PHR modifier , - Sn Stabilizer 1.25 PHR 10 Internal Lubricant 0.75 PHR For Comparison Examples B and C and 5 Example 2, the test conditions were as follows: Temperature Temperature Speed of Graduation Material Cylinder 0 (° C) (° C) (RPM) Front Cylinder 204 171 18.5 Rear Cylinder 193 163 23 5 The space of the fastening point was .381 mm. In order to obtain an adhesion time, the amount of the external lubricant used was halved as compared to the amount of the external lubricant used in Comparative Example A and Example 1.

LUBRICANT EXTERNAL TIME TIME BAND ADHESION COMP. B 0.125 Loxiol 30 seconds 20 minutes G70S at 1 minute COMP. 0.0625 of 30 seconds After a Polyethylene at 1 minute hour, no A-C (R) 316 adhesion EXAMPLE 2 0.0625 of 30 seconds After a Polyethylene at 1 minute hour, no A-C <R) 307 adhesion For Example B Comparison, no visible thinning occurred but the product had a slightly brownish tint when banded and some defects on the surface so that it did not result in a clear product. For Comparison Example C, the thinning occurred in the initial cylinder but appeared to be cleared with a possible blue nebulosity in the cylinders and more defects occurred on the surface compared to Example B of Comparison but no brownish tinge occurred. For example 2, thinning occurred in the initial cylinder but it seemed to clear with a ,, possible blue nebulosity on the surface of the cylinder and 0 more defects occurred on the surface compared to Comparison Example C but the brownish tint did not occur. For Comparison Examples D and E and Example 3, high cylinder temperatures were used to obtain an adhesion time for the Loxiol G70S: Temperature Temperature Speed of Graduation Material Cylinder 0 or Adjustment (° C) (RPM) Front Cylinder 216 185 18.5 Rear Cylinder 204 177 23 5 The space of the fixing point was .381 mm LUBRICANT EXTERNAL TIME TIME BAND ADHESION COMP. D 0.125 Loxiol from 0 to 30 5 minutes G70S seconds COMP. 0.0625 from 0 to 30 after Polyethylene seconds 30 minutes, A-C < R) 316 non-adherence EXAMPLE 3 0.625 from 0 to 30 after Polyethylene seconds 1.5 hours, A-C < R) 307 non-adhesion For Example D Comparison, thinning did not occur but the product had a slightly brownish dye during banding and some defects on the surface so that it did not result in a clear product. For Comparative Example E, the thinning occurred in the initial cylinder and more defects occurred on the surface compared to Comparative Example D but no brownish tinge occurred. For Example 3, the thinning occurred in the initial cylinder and more defects occurred on the surface compared to the Comparative Example E but no brownish tinge occurred. For Comparison Examples 1F and G and Example 4, the amount of external lubricant used was increased to determine if slimming would occur: LUBRICANT EXTERNAL TIME TIME BAND ADHESION BAND COMP. 0.25 Loxiol from 0 to 30 After 40 G70S second minutes non-adhesion COMP. G 0.125 from 0 to 30 After 40 Polyethylene seconds, A-C < R) 316 non-adherence EXAMPLE 4 0.125 from 0 to 30 After 40 seconds polyethylene, A-c'R) 307 non-adhesion For Example F Comparison, no thinning occurred but some defects occurred on the surface so that it did not result in a clear product. For Comparative Example G, thinning occurred in the initial cylinder but was cleared after banding and more defects occurred on the surface compared to Comparative Example F, but in total the color was better. For Example 4, thinning occurred in the initial cylinder that appeared to clear after banding and more defects occurred on the surface compared to Example G Comparison. For Comparison Examples H and I, the amount of Polyethylene A-C (R) 316 was reduced in order to try to obtain an adhesion time.

LUBRICANT EXTERNAL TIME TIME BAND ADHESION COMP. H 0.03125 from 0 to 30 Polyethylene adhered seconds after 5 A-C (R) 316 minutes COMP, 0.0416 from 0 to 30 after 30 Polyethylene seconds, not Ac (R > 316 adhesion Field tests have shown that Ac (R) 316 polyethylene becomes thinner over time while with polyethylene Ac (R) 307, no thinning has been observed.

Claims (10)

t ~ t CLAIMS:

1. A composition comprising: (a) a vinyl polymer; 5 (b) an amount effective to stabilize the vinyl polymer of a tin stabilizer; and (c) an effective amount to lubricate the polyethylene vinyl polymer having a viscosity - Brookfield at a temperature of 140 ° C greater than 0 about 85,000 centipoise, and an acid number as determined by normalized KOH titration of between about 5 and about 9.

The composition according to claim 1, in where the vinyl polymer is polyvinyl chloride.

3. The composition according to claim 1, wherein the tin stabilizer is a tin thioglycolate.

4. The composition according to claim 3, wherein the tin thioglycolate is octyltin thioglycolate.

The composition according to claim 1, wherein the polyethylene is present in an amount of about 0.01 to about 10 5 parts by weight per 100 parts of the vinyl polymer.

6. The composition according to claim 1, wherein the polyethylene is present in an amount of about 0.05 to about 5 parts by weight per 100 parts of the vinyl polymer.

7. A calendered sheet comprising: (a) vinyl polymer; (b) an amount effective to stabilize the vinyl polymer of a tin stabilizer; and, K. (c) an amount effective to lubricate the polyethylene vinyl polymer having a Brookfield viscosity at a temperature of 140 ° C greater than about 85,000 centipoise and an acid number as determined by standardized KOH titration of between about 5 and about 9.

The calendered sheet according to claim 7, wherein the vinyl polymer is polyvinyl chloride.

9. The calendered sheet according to claim 7, wherein the tin stabilizer is 0 tin thioglycolate. The calendered sheet according to claim 7, wherein the polyethylene is present in an amount of about 0.01 to about 10 parts by weight per 100 parts of the vinyl polymer.