CA1236250A

CA1236250A - Chlorinated polyethylene elastomers

Info

Publication number: CA1236250A
Application number: CA000459819A
Authority: CA
Inventors: Royce E. Ennis
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1983-07-29
Filing date: 1984-07-26
Publication date: 1988-05-03
Also published as: EP0133294A1; JPH0421683B2; EP0133294B1; JPS6049003A; DE3475715D1; US4591621A

Abstract

TITLE
CHLORINATED POLYETHYLENE ELASTOMERS
ABSTRACT OF THE DISCLOSURE
An uncured chlorinated polyethylene elastomer having a molecular weight distribution of about 6-13, as determined by the ratio of where ?w represents the weight average molecular weight and ?n represents the number average molecular weight, a chlorine content of about 20-28% by weight, a Mooney viscosity value, determined according to ASTM
D 1646-81, ML(1 + 4) at 100°C, of about 15-36; and, optionally, a sulfur content of about 0.2-2% by weight and a process for their preparation.

Description

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TITLE
CHLORINATED POLYETHYLENE ELASTOMERS
BACK GROW D OF THE INVENTION
This invention relates Jo a novel 5 chlorinated polyolefin elastomers having unique physical characteristics and to a process for waking the same The chlorinated polyolefins, ire., chlorinated polyethylene and chlorosulfonated polyethylene, have rubber-like properties due to the substitution of chlorine atoms into the polyethylene. These elastomers are resistant to deterioration due to ozone, they are resistant to solvents and they have a high resistance to the swelling action of oils. Chlorosulfonated polyethylene has sulfonyl chloride groups in the elastomers and these groups provide sites of reactivity through which cross linking or curing, if desired, can be effected.
Chlorinated polyethylene and chlorosulfonated polyethylene elastomers have been use to coat fabrics to make tarpaulins, to make industrial pump diaphragms, to make conveyor belts, for wire and cable jacketing, and, more recently, they have been use as pond and pit liners, and roofing film. The uncured elastomers are sold as such and usually they are subsequently compounded with acid acceptors, pigments. fillers, and the live, and formed into products by, for example, calendering or extrusion processes. These chlorinated polyethylene elastomers can also be cured by conventional procedures. Prior to the present invention, when chlorinated polyethylene elastomers were formed, especially when the elastomers was AD-5375 35 calendered or extruded, it was very difficult to feed I`

the uncured compounded elastomers into the equipment, for example, the nip of the counter-rotating calender rolls, so what the rollers or other feeding mechanism would readily pick up the uncured compounded elastomers to form a finished product. More importantly, wren extruding the compounded chlorinated polyethylene known prior to the present invention into sheets or films it was not possible to substantially draw down the sheets or films to reduce their thickness without rupturing them. The present invention provides a chlorinated polyethylene elastomers that can be substantially drawn down without rupturing or breaking to make a wider range of thickness of sheets or films.
Prior to the present invention in order to make an elastomers that processes more readily and shows an improvement in elongation, it was necessary to add to the elastomers rather large amounts of plasticizer and to use higher temperatures when calendering. The audition of plasticizers in amounts sufficient to improve elongation adversely affects the properties of the elastomers In addition, if the temperatures used during the calendering operation are increased, for example, to about 150-165C when processing chlorosulfonated polyethylene, in order to sufficiently lower the viscosity of the chlorinated polyethylene elastomers for ease of processing, the elastomers starts to decompose. Furthermore, such temperatures increase the potential for S02 evolution and scorching, i.e., premature vulcanization.
The present invention provides a novel uncured chlorinated polyethylene elastomers that has valuable characteristics of other chlorinated polyethylene, but, in addition, the uncured elastomers is easily processible and, quite surprisingly, the elastomers even when compounded can be elongated substantially more than known chlorinated polyethylene elastomers without rupturing or breaking.
SPRY OF THE IVY SHEA
The present invention provides a novel uncured chlorinated polyethylene elastomers having:
(a) a molecular weight distribution of 1 about 6-13, as determined by the ratio of My where My My represents the weight average molecular weight and My represents the number average molecular weight;
(b) a chlorine content of about 20-28%, preferably 22-26%, by weight; and (c) a Lyon viscosity value, determined according to ASTM D 1646-81, MY 1 4) at 100C, of about 15 36, preferably 18-25, and (d) optionally, a sulfur content of about 0.2-2% by weight.
The uncured chlorinated polyolefin elastomers are prepared by mixing polyethylene with chlorine or a chlorine-generating material at elevated temperatures, said polyethylene hazing a flow rate of about 1-8 grams per 10 minutes as determined by ASTM D 1238 Condition E, and a molecular weight distribution of about 6-13 as determined by the ratio of My where My represents the My weight average molecular and My represents the number average molecular weight, and adding to the polyethylene an amount of chlorine or chlorine-gener~ting material sufficient to incorporate into the polyethylene about 20-28%, preferably 22-~6~, by weight chlorine.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
_ _ _ . _ An important feature of this invention it the selection of the polyethylene that is used in the process. To obtain the desired results of a readily processible chlorinated polyolefin elastomers that is capable of hot elongation at temperatures just above the melting point of the elast~mer one must use in the process a linear polyethylene, preferably having a density of about 0.94-0.97 g/cc, that has a flow rate of about 1-8, preferably 2-7, grams per 10 minutes as determined by ASTM 1238 Condition E
secondly, the polyethylene must have a molecular weight distribution of about 6-13, preferably 6 - 9, as determined by the ratio of M where My represents the weight average molecular My weight and My represents the number average molecular weight of the polyethylene. Both the molecular weight determinations are made by gel permeation chromatography as described in, for example, Gel Chromatography by Cramer and Buyers, John Wiley Publishing Co. (1979). Although it is preferred to use linear polyethylene homopolymer in the process, optionally the polyethylene can contain an alpha-olefin comonomer in an amount of less than about 10% by weight, such as buttonhole and octene-l.
The polyethylene becomes elastomeric when chlorine atoms are incorporated into the polymer which lessens the degree of crystallinity of the polymer. The polyethylene can be chlorinated at elevated temperatures, usually about Luke, with gaseous chlorine or a chlorine-generating material.

This process can be carried out in solution in on inert solvent, i.e., inert to the reactants, or in a suspension in an inert nonsolvent or without a solvent, all of which processes are known in the art and described, for example, in U.S. Patents 3,759,888 and 3,347,835. These processes are usually conducted in the presence of conventional free-radical initiators, such as organic peroxides or aliphatic ago compounds. Zen the chlorination is conducted in an inert solvent, suitable solvents include chlorinated solvents, aromatic hydrocarbons and, specifically, carbon tetrac~loride, tetrachloroethane, chloroform, chlorobenzene and trifluorochloroethane, or mixtures thereof.
Suspension chlorination of the polyethylene is usually conducted in water. The amount of gaseous chlorine or chlorine-generating material that is used in the process must ye sufficient to incorporate into the polyethylene about 20-28% by weight, preferably 22-26% by weight, chlorine. If less than abut 20~
by weight chlorine is incorporated into the polymer the crystallinity is undesirably high and if more than about 28% by weight chlorine is incorporated into the polymer the crystallinity is unacceptably low.
When polyethylene is chlorinated in the presence of sulfur dioxide and/or sulfuryl chloride, or if the reactions are conducted sequentially, sulfonyl chloride groups are introduced into the polymer. The sulfonyl chloride groups that are introduced into the elastomers do not significantly alter its physical properties, but allows the elastomers to be cross linked or cured, usually with polybasic metal oxides, especially lethargy (Pro), magnesium oxide, or polybasic metal salt of weak 36~

acids, such as tribasic lead Malta. The amount of sulfur in the form of sulfonyl chloride groups in the elastomers is from about 002-2% by weight, usually about 1% by weight.
The chlorinated polyethylene or chlorosulfonated polyethylene elastomers are correctors as having: a molecular weight distribution of about 6-13, as determined by the ratio of My where My represents the My weight average molecular weight and My represents the number average molecular weight, a chlorine content of about 20-28% by weight, a Mooney viscosity value, determine according to ASTM D 1646-81, Mull 4) 1 at 100C of 15-36. The percent elongation of the chlorosulfonated polyethylene compounder with non reinforcing fillers, at 60C, or at a temperature which is just above the melting point of the elastomers and determined according to ASTM D 412, as illustrated in detail hereinbelow in examples, shows the extraordinarily high percent elongation obtained with the elastomers made using the conditions of the present process, as compared to chlorosulfonated polyethylene known in the art. Similar results can be obtained with chlorinated polyethylene of the same chlorine level containing the same compounded ingredients, and tested just above its melting point e.g., about 709C. The percent elongation of the elastomers were measured at 60C and determined according to ASTM D 412, at a draw rate of 50 cm. per minute when the chlorosulfonated polyethylene were compounded with the ingredients listed below in the examples.
The high amount of elongation without rupturing or breaking a sheet of the uncured I

elastomers at a temperature just above its melting point is an important characteristic. The uncured chlorinated polyethylene 21astomers which are usually compounded with fillers, acid acceptors, plasticizers, pigments, processing aids and the like can be fed to forming equipment and, for example, film can be conveyed and drawn down without rupturing or breaking the stock, which commonly occurs with elastomers 5 made according to the teachings of the prior art. This permits one to conduct the forming process at higher rates. It also provides for the preparation of a wiser range of films or sheet sizes, and it reduces the amount of manual labor required to prepare these formed products.
The chlorinated polyethylene elastomers described herein are especially useful in the uncured compounded condition as roofing film and pond and pit liners.
The following examples will serve to further illustrate the invention, parts and percentages are by weight unless otherwise indicated.
Example 1 A stirred autoclave was charged with 18.16 kg of carbon tetrachloride and 1.35 kg of linear polyethylene having a density of 0.960 g/cc, a flow rate of 4.2 grams per 10 minutes and a molecular weight distribution ratio of Mom of 11.
The autoclave was closed and heated to Luke and pressurized to 25 prig (0.29MPa) to dissolve the polyethylene. A feed of initiator solution I

2,2'-aæobis-~2-methylpropanenitrileJ in chloroform) was begun and maintained at a rate of 3 ml per minute throughout the remainder of the reaction. The temperature was reduced to 105C and a chlorine feed was begun and a total of 0.38 kg of chlorine was B

pus into the reaction over period of 72 minutes. After 30 minutes from initiation of ache reaction a feed of aulfuryl chloride was begun and 600 ml was added over a period of 20 minute. After the addition of clown was complete, the pressure on the reactor was release and the sample was dega6sed at lOOD-75-C. A stabilizer solution of 1%
Epon*B28 epoxy resin (condensation product of epichlorohydrin and bisphenol A with a neutralization equivalent of 18~) in CC14 was added in an amount of 2.7 go The solution was filtered and the polymer was isolated by drum drying. The chlorosulfonated polyethylene product contained 23.6% Of and 1.07~ S, an the Money viscosity was 21. The Mom ratio was lo unchanged at 11.
Example 2 A stirred autoclave was charged with 18.16 kg of carbon tetrachloride and 1~36 kg of linear polyethylene having a density of 0.94~ g/cc, a slow rote of 3.5 grays per 10 minutes and a molecular weight distribution ratio of Mom of 9.5.
the autoclave was closed and heated Jo Luke and pressurized to 25 prig (0.29MPa) to dissolve the polyethylene. A fee of initiator solution (1%
2,2'-azobis-[2-methylpropanenitrile~ in chloroform) was begun and maintained at a rate of 3 ml per minute throughout the remainder of the reaction. The temperature was reduced to 104-C end a chlorine feed I was begun. A total of 0.38 I of chlorine was Swede into the reaction over a period of 72 minutes. After 25 minutes from the beginning of the reaction a feel of sulfuryl chloride was begun and 600 I way added over a period of I minutes. After the addition of *denotes trade mark ~362~i~

chlorine was complete, the pressure on the reactor was release and sample was degassed at about 100-75~C. A stabilizer solution of Eon R28 (1% in CC14 solvent) was added in an amount of 2.7 kg.
The solution was filtered and the polymer was isolated by drum drying. The chlorosulfonated polyethylene product contained 23.5% Of and 1.13% S, and the Mooney viscosity was 22Ø Mom ratio was unchanged at 9.5 En A stirred autoclave was charged with 18.16 I of carbon tetrachloride and 1.36 kg of linear polyethylene having a density of 0.954 g/cc, a flow rate of 3.1 grams per 10 minutes and a molecular weight distribution ratio of Mom of 9.9.
The autoclave was closed and heated to 110C and pressurized to 25 prig (0.29MPa) to dissolve the polyethylene. A feed of initiator solution (1%
2,2'-azobis-[2-methylpropanenitrile] in chloroform) was begun and maintained at a rate of 3 ml per minute throughout the remainder of the reaction. The temperature was reduced to 105C and a chlorine feed was begun. A total of 0.36 kg of chlorine was passed into the reaction over a period of 78 minutes. After 22 minutes from initiation of the reaction, a feed of sulfuryl chloride was begun an 600 ml was added over a period of 18 minutes. A feed of sulfur dioxide was begun after approximately 3 hours and 0.18 kg S02 was added over a period of 12 minutes. Aster the addition of chlorine and S02 was complete, the pressure on the reactor was released and sample was degassed at 85-67C. A stabilizer solution of Eon 828 if% in CC14 solvent) was added in an amount of 2.7 kg. The solution was filtered and the polymer was isolated by drum drying. The chlorosulfonated ~:3~2~

polyethylene product contained 23~4~ Of and 0.97~ S, and the Mooney viscosity was 22.5. Mooney ratio was unchanged at 9.9.
Hot Elongation Test Data for Eagles 1-3 The polymer of Example 1-3 and control polymer (consisting of chlorosulfonated polyethylene having ML4 Luke) of 37~ Of content of 23.5~ and S
content of 1.0% prepared from polyethylene of melt flow rate 2.8 and Mom of 5) were compounded and tested as follows. A sample of 689 Maglite D (Moo), 595 9 Topper (Shea), 1105 9 Atomize Whiting*
(Cook), 179 2,6-di-t-butyl-4-methylphenol, 25.59 Carb~wax*S (polyethylene oxide glycol) and 10.29 Commodious (strummed) were mixed and added to a water-cooled 00 Banbury*mixer followed by addition of a 17009 sample of the polymer. This represents a ratio of polymer/MgO/Ti~2/CaC03/2,6~di-t-butyl-4-methyl-phenol/Carbow~x S/Kemamide S of 100/4/35/65/1/1.5/0.6. The polymer stock was mixed until the temperature of the stock reached 100-110C
at which point toe stock was removed and sheeted out on a rubber mill. A portion of the stock was rewarmed on the mill and then applies to the nip of a laboratory calender with B inch rolls. Calendared films measuring 0.03 in (7.6 mm) were prepared with the nip ox the rolls set at 0.92B in (23.6 mm). The temperature of the calendering rolls was 250JF
(121-C). Dip C dumbbells were prepared for sac of the polymers a described in ASSET D-412 and were died out in the machine direction of the calendered sweet. These dumbbells were tested for elongation at break at 60C at a draw rate of 50 cumin as described in ASTM D 412. The result art shown in Table I.
*denotes trade mark Table I
Sample EN (~) at 60DC
Control Polymer 565 Polymer of Example 1 >1000 Polymer of Example 2 >1000 - Polymer of Example 3 >1000 From the above data it can be seen that the uncured chlorosulfonated polyethylene of the present invention can be formulated into compounded stocks having excellent hot extensibility.

A stirred autoclave was charged with 34.05 kg of carbon tetrachloride and 2.56 kg of linear polyethylene having a density of 0.950g/cc, a flow rate of 1.1 grams per 10 minutes and a molecular weight distribution ratio of Mom of 13.
The autoclave was closed and heated to 110C and pressurized to about 25 prig (0.29MPa) to dissolve the polyethylene. A fee of initiator solution (1%, 2,2'-azobis-[2-methylpropanenitrile] in chloroform) was begun and maintainer at a rate of 3 ml per minute throughout the remainder of the reaction. The temperature was reduced to 105C and a chlorine feed was begun. A total of 0.89 kg of chlorine was passed into the reaction over a period of 115 minutes.
After 29 ~inutas from initiation of reaction a feed of sulfuryl chloride was begun and 95$ ml was added over a period of 26 minutes. after 3 yours and 15 minutes had elapsed from initiation of the reaction, a feed of sulfur dioxide was begun and Oriole kg of So was added over a period of I minutes. After the addition of chlorine was complete the pressure on the realtor was released and the sample was degassed at Luke. A stabilizer solution of Eon B28 (1%
in CCL4 solvent) was added in an amount of 5.1 kg.

I
I
The Solon was filtered and the polymer was isolated by drum drying. The chlorosulfonated polyethylene product contained 23.2~ Of and 1.04% S, and the Mooney viscosity was 35.5 Mom ratio was unchanged at 13.
E
A stirred autoclave was charged with 36.6 kg of carbon tetrachloride and 2.72 kg of linear polyethylene having a density of 0.955g/cc, a flow rate of 3.B grams per 10 minutes an a molecular weight distribution ratio of Mom of 9.9.
The autoclave was closed and heated to 110~C and pressurized to 25 prig (0.29MPa) to dissolve the polyethylene. A feed of initiator solution I
2,2'-a7Obis-~2-methylpropanenitrile] in chloroform) was begun and maintained at a rate of 3 ml per minute throughout the remainder ox the reaction. The temperature was reduced to 106DC, and a chlorine feed was begun. A total of 0.78 kg of chlorine was passed into the reaction over a period of 3.5 hours. After 34 minutes a feed of sulfuryl chloride was begun and 1200 ml was added over a period of 36 minutes. After approximately 3 hours and 20 minutes had elapsed from initiation of the reaction, a feed of sulfur dioxide was begun A total of 0.104 kg of S02 was added over a period of 18 minutes. After the addition of chlorine was complete, the pressure on the reactor was released and sample was degassed at 86-67C. A
stabilizer solution of Eon 828 to in Cal solvent) was added in an amount of 5.4 kg. The solution was filtered and the polymer was isolated by drum drying. The chlorosulfonated polyethylene product contained 23.5% Of an 0.93~ S, no the Mooney viscosity was 21~5. The Mom ratio was unchanged I

Hot Elongation Text Data for Examples 4-5 The polymers of Examples 4~5 and a Control Polymer (consisting of chlorosulfonated polyethylene having ML4 (100C) of 37, Of content of ~3.5~ and S
content of 1.0~ prepared from polyethylene of melt flow rat 2.8 and Mom ratio of 5) were compounded, mixed, calendered and formed into test specimens as described hereinabove for the hot elongation tests of Examples 1-3, with the exception that 2,6-di-t-butyl-4-me~hylphenol was omitted from the formulation. The results are shown in Table II.
table II
Sample (~) at 60C
Control Polymer 900 Polymer of Example 4 >1030 Polymer of Example 5 >1083 As can be seen from the above data, uncured chlorosulfonated polyethylene of the present invention can be formulated into compounded stocks having excellent hot extensibility.
En A stirrer autoclave wit charged with 32.7 kg of carton tetrachloride and 2.48 kg of linear polyethylene having a density of 0.956 g/cc, a flow rate of I grams per 10 minutes and a molecular weight distribution ratio of Mom of 7.5.
The autoclave was closed and heated to Luke and pressurized to 25 prig (0029MPa) to dissolve the polyethylene. A feed of initiator solution I
2,2'-a~obis-C2-methylpropanenitrile~ in chloroform) was begun and maintained at a rate of 3 ml/min.
throughout the remainder of the reaction. chlorine feed was begun and a total of 1~72 kg of chlorine way passed into the reaction over a period of approximately 4.25 hours. After the addition of chlorine was complete, the pressure on the reactor was released and sample was degassed at about 100-75C. A stabilizer solution of Eon 828 (1% in CC14 solvent) was added in an amount of 5.0kg. The solution was filtered and the polymer was isolated by drum drying. The chlorinated polyethylene product - contained 26.2% Of and the Mooney viscosity was 20.5. The Mom ratio was unchanged at 7~5.
1 0 Jo A stirred autoclave was charged with 18,16 kg of carbon tetrachloride and 1.36 kg of linear polyethylene having a density of 0.956 g/cc, a flow rate of 5,6 grams per 10 minutes and a molecular weight distribution ratio of Mom of 7.5.
The autoclave was closed and heated to lO9DC and pressurized to 25 prig (0.2gMPa) to dissolve the polyethylene. A feed of initiator solution I
2,2'-azobis-[2-methylpropanenitrile] in chloroform) was begun and maintained at a rate of 3 ml per minute throughout the remainder of the reaction. The temperature was reduced to 105C and a chlorine feed was begun. A total of 0.37 kg of chlorine was passed into the reaction o'er a period of 155 minutes.
After 35 minutes from initiation of the reaction a fee of sulfuryl chloride was begun and 600 ml was added over a period of 15 minutes. After approximately 2, 5 hours had elapsed from initiation of reaction, a feed of sulfur dioxide was begun. A
total of 0.076 kg of S02 was added over a period of 8 minutes, After the addition of chlorine and S02 was complete the pressure on the reactor way roused and the sample was degassed at about 100~-68~C. A
stabilizer solution of Eon B28 I in Cal solvent) was added in an amount of 2.7 kg. The I
solution was filtered an the polymer was isolated by drum drying. The chlorosulfonated polyethylene product contained 24.1~ Of and OWE% S and the Mooney viscosity was 18.5.

Claims

16

1. In a process for making an uncured chlorinated polyolefin elastomer which comprises mixing polyethylene with chlorine or a chlorine-generating material at elevated temperatures, the improvement which comprises said polyethylene having a flow rate of about 1-8 grams per 10 minutes as determined by ASTM D 1238 Condition E, and a molecular weight distribution of about 6-13 as determined by the ratio of where ?w represents the weight average molecular weight and ?n represents the number average molecular weight, and adding to the polyethylene an amount of chlorine or chlorine-generating material sufficient to incorporate into the polyethylene about 20-28% by weight chlorine.

2. In a process for making an uncured chlorosulfonated polyolefin elastomer which comprises mixing polyethylene with chlorine or a chlorine-generating material in the presence of sulfur dioxide or sulfuryl chloride at elevated temperatures, the improvement which comprises said polyethylene having a flow rate of about 1-8 grams per 10 minutes as determined by ASTM D 1238 Condition E, and a molecular weight distribution of about 6-13 as determined by the ratio of where ?w represents the weight average molecular weight and ?n represents the number average molecular weight and adding to the polyethylene an amount of chlorine or chlorine-generating material sufficient to incorporate into the polyethylene about 20-28% by weight chlorine.

3. A process of Claims 1 or 2 wherein the polyethylene has a flow rate of 2-7 grams per 10 minutes and adding to the polyethylene an amount of chlorine or a chlorine-generating material sufficient to incorporate into the polyethylene an amount of 22-26% by weight chlorine.

4. A process of Claim 1 wherein the chlorination is carried out in an inert solvent.

5. A process of Claim 2 wherein the chlorosulfonation is carried out in an inert solvent.

6. An uncured chlorinated polyethylene elastomer having:
(a) a molecular weight distribution of about 6-13, as determined by the ratio of where ?w represents the weight average molecular weight and ?n represents the number average molecular weight;
(b) a chlorine content of about 20-28% by weight;
(c) a Mooney viscosity value, determined according to ASTM D 1646-81, ML(1 + 4) at 100°C, of about 15-36, and (d) optionally, a sulfur content of about 0.2-2% by weight.

7. An uncured chlorosulfonated polyethylene elastomer having:
(a) a molecular weight distribution of about 6-13, as determined by the ratio of where ?w represents the weight average molecular weight and ?n represents the number average molecular weight;
(b) a chlorine content of about 20-28% by weight;
(c) a Mooney viscosity value, determined according to ASTM D 1646-81, ML(1 + 4) at 100°C, of about 15-36; and (d) a sulfur content of about 0.2-2 percent by weight.

8. An uncured chlorosulfonated polyethylene elastomer of Claim 7 having a chlorine content of about 22-26% by weight.

9. An uncured chlorosulfonated polyethylene of Claim 8 having a Mooney viscosity value, determined according to ASTM D 1646-81, ML(1 + 4) at 100°C, of about 18-25.