GB1580617A - Internally plasticized vinyl chloride copolymer - Google Patents

Abstract

An internally plasticised copolymer comprises from 50 to 85% by weight of vinyl chloride, from 3 to 47% by weight of at least one C6- to C10-alkyl acrylate and from 3 to 47% by weight of at least one bis(hydrocarbyl) vinyl phosphonate of the formula I. The substituents in the formula I are as defined in Claim 1. This copolymer can be prepared by known suspension, emulsion, solution or bulk polymerisation methods and can be used, without addition of significant amounts of external plasticisers, for purposes for which externally plasticised vinyl chloride polymers are usually suitable. The use of this copolymer overcomes the migration problems associated with externally plasticised polyvinyl chloride systems. <IMAGE>

Description

(54) INTERNALLY PLASTICIZED VINYL CHLORIDE COPOLYMER (71) We, STAUFFER CHEMICAL COMPANY, a corporation organised under the laws of the State of Delaware, United States of America, of Westport, Connecticut 06880, United States of America; do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an internally plasticized vinyl chloride copolymer; more particularly, it relates to an internally plasticized copolymer of vinyl chloride, an alkyl acrylate and a bis (hydrocarbyl)vinylphosphonate.

External plasticizers in vinyl chloride homo- and co-polymers are commonly employed today to form products having the required degree of flexibility for a given purpose. Such external plasticization, however, is not entirely satisfactory since the plasticizer tends to migrate to the surface and eventually is lost either by volatilization or extraction. This loss gives rise to such problems as surface stickiness, automotive windshield fogging and embrittlement of vinyl films containing the polymer which are used in such applications as shower curtains, baby pants and vinyl seat covers. Hence, various proposals for "internal plastization" of vinyl chloride polymers have been made wherein the plasticizing action is supplied by one or more comonomers for vinyl chloride which are polymerized with the vinyl chloride to form the polymer.

The use of copolymers of a vinyl monomer and a polymerizable polyester, for example, an acrylate or a vinyl ester of a polyester of an aliphatic hydroxycarboxylic acid, was proposed in U.S. Patent No. 3,640,927. An internally plasticized, two component vinyl chloride copolymer containing from 75 to 95% chloride and from 25 to 5% of an ester of an unsaturated mono- or poly-carboxylic acid, e.g. a C6-C12 alkyl maleate, fumarate or acrylate, was proposed in U.S. Patent No. 3,544,661. A four component polymer composition containing vinyl chloride, a dialkyl maleate or fumarate, an alkyl ester of acrylic or methacrylic acid and a monohydrogen, monoalkyl maleate or fumarate was proposed in U.S. Patent No. 3,196,133 for use as a solvent-based coating having both good adhesiveness and flexibility. In U.K. Patent No. 1,517,428 an internally plastized copolymer of vinyl chloride, a Cl-ClO alkyl acrylate and a C8C22 dialkyl maleate or fumarate is disclosed.

Two component copolymers of vinyl chloride and acrylates, such as 2-ethylhexyl acrylate, as seemingly suggested by certain portions of U.S. Patent No. 3,544,661 produce heterogeneous resin compositions which do not show the desirable performance properties of flexible vinyl films according to the present invention.

A variety of two component vinyl chloride/vinylphosphonate copolymers are kno?vn which cannot be classified as internally plastized copolymers (U.S. Patent Nos. 3,691,127; 3,792,113 and 3,819,770) since copolymerizing just vinyl chloride and a bis(hydrocarbyl)vinylphosphonate, e.g. bis(beta chloroethyl) vinylphosphonate, leads to production of a resin which gives a hard relatively unflexible film requiring external plasticization. It does not appear to have been hitherto appreciated that a vinyl chloride/acrylate/vinylphosphonate copolymer, as described herein, would have flexibility characteristics as well as performance properties equivalent in many respects to externally plasticized polyvinyl chloride without having to add a substantial amount of external plastizer. Unexpectedly, the bis(hydrocarbyl)vinylphosphonate monomer aids in rendering the terpolymer less heterogeneous in appearance and resulting properties than if only vinyl chloride and an alkyl acrylate were used as comonomers as suggested by certain prior art references. The copolymer also has reduced smoke generation characteristics.

The copolymer according to the present invention is an internally plasticized vinyl chloride copolymer of from 50 to 85%, by weight, of vinyl chloride, from 3 to 47%, by weight, of C6-C10 alkyl acrylate, e.g. 2-ethylhexyl acrylate and from 3 to 47%, by weight, of bis (hydrocarbyl)vinylphosphonate (as hereinafter defined), e.g. bis (betachloroethyl)vinylphosphonate. The copolymer is prepared using conventional suspension, emulsion, bulk and solution polymerization techniques and may be used in those applications where externally plasticized polyvinyl chloride is used, e.g., as a vinyl film or sheeting material, in vinyl wire and cable insulation, as vinyl flooring, and as bag and tubing for blood transfusion equipment.

It has been unexpectedly found that a flexible vinyl film prepared from an internally plasticized vinyl chloride polymer without any external plasticization exhibits a Clash-Berg value of about 0 C. or below, preferably about -15 C. or below, and a tensile strength at break of at least 60 kg./cm.2 or higher, preferably about 85 kg./cm.2 or greater. Such an internally plasticized polymer may be prepared using conventional emulsion, suspension, bulk and solution polymerization procedures by using a basic three component monomer charge which contains certain amounts of vinyl chloride, a C6-C10 alkyl acrylate and a bis(hydrocarbyl)vinylphosphonate, e.g. bis(beta-chloroethyl)vinylphosphonate. The present invention is, more particularly an internally plasticized copolymer which contains from 50 to 85 %, by weight, of vinyl chloride, from 3 to 47 %, by weight, of C6-C lo alkyl acrylate and from 3 to 47%, by weight, of bis(hydrocarbyl)vinylphosphonate copolymerized therein. As used herein, the term "bis(hydrocarbyl)vinylphosphonate" means a compound corresponding to the following general formula:

wherein X represents hydrogen, halogen, cyano, aryl, such as phenyl, Cl-Cl8 alkyl or

and R and R', independently represent optionally substituted hydrocarbyl groups containing up to 18 carbon atoms, or Rand R', taken together with the -O-P-O- linkage, may complete a single radical.

The hydrocarbyl groups may be substituted one or more times with non-interfering substitments, i.e. with groups which do not interfere with the polymerization of the bis(hydrocarbyl)vinylphosphonate. Such substituents include, for example, chloro, bromo, fluoro, nitro, hydroxy, sulphone, ethoxy, methoxy, nitrile, ether, ester and keto.

In the above general formula, R and R' represent optionally substituted hydrocarbyl group which may be aliphatic or aromatic, for example, alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl and nonyl; alkenyl groups, such as pentenyl and hexenyl and isomers thereof; cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl; cycloalkenyl groups, such as cyclohexenyl; and aryl groups, such as phenyl, benzyl, phenethyl, tolyl and naphthyl.

Representative of the above-defined bis (hydrocarbyl)vinylphosphonates include: bis beta-chloroethyl)vinylphosphonate; bis 2-ethylhexyl)vinylphosphonate; bis beta-chloropropyl)vinylphosphonate; bis beta-chloroethyl 1-methylvinylphosphonate; bis beta-chloroethyl 1-cyanovinylphosphonate; bis (beta-chloroethyl) 1-chlorovinylphosphonate; bis (beta-chloroethyl) l-phenylvinylphosphonate; dimethyl vinylphosphonate diethyl vinylphosphonate; bis (omega-chlorobutyl)vinylphosphonate; di-n-butyl vinylphosphonate; di-isobutyl vinylphosphonate; bis(2-chloroisopropyl) 1-methylvinylphosphonate diphenyl vinylphosphonate; and bis(2,3-dibromopropyl)vinylphosphonate.

Among the above bis(hydrocarbyl)vinylphosphonate monomers, it is preferred to employ bis(beta-chloroethyl)vinylphosphonate in preparing the polymers according to the present invention since this monomer is a commercially available material, lower in cost than the other bis(hydrocarbyl)vinylphosphonates. Bis(2-ethylhexyl)vinylphosphonate is also a preferred monomer since it gives a product having very desirable physical properties, such as good low temperature flexibility.

Representative C6-C10 alkyl acrylates which may be used in the practice of the present invention include: n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate and mixtures thereof. The C8-Cl0 alkyl acrylates are preferred for use, especially the branched alkyl compounds, for example, 2-ethylhexyl acrylate, since such branched alkyl groups give better physical properties to the resulting resin.

Mixtures of the alkyl acrylates and of the vinylphosphonates may be used, if desired.

One preferred copolymer from the standpoint of cost and performance is a terpolymer containing from 55 to 80%, by weight, of vinyl chloride, from 10 to 35%, byweight, of C6-Cl0 alkyl acrylate and from 5 to 25neo, by weight, of bis (C i-Cs alkyl) or (Cl-C8 haloalkyl) vinylphosphonate copolymerized therein. One terpolymer which may be used to form films having a Shore "A" hardness of from 60 to 72 contains from 56 to 58%, by weight, of vinyl chloride, from 29 to 310/0, by weight, of C6-C10, preferably C8-Cl0, alkyl acrylate, e.g.

2-ethylhexyl acrylate, and from 11 to 13%, by weight, of vinylphosphonate, e.g. bis(betachloroethyl)vinylphosphonate or bis(2-ethylhexyl)vinylphosphonate. For a harder film having a Shore "A" hardness of from 80 to 90, a higher vinyl chloride content is needed. This is easily accomplished by raising the vinyl chloride content and correspondingly reducing the acrylate and vinylphosphonate contents. For example, a terpolymer having a Shore "A" hardness of from 85 to 95 may contain from 73 to 75 %, by weight, of vinyl chloride, from 17 to 19%, by weight, of C6-Cl0 alkyl acrylate, e.g. 2-ethylhexyl acrylate, and from 7 to 9%, by weight, of bis(hydrocarbyl)vinylphosphonate, e.g. bis(beta chloroethyl)vinylphosphonate.

The present copolymer may be preferred using conventional bulk, emulsion, suspension and solution polymerization procedures. Suspension polymerization is preferred since it avoids the problems of isolation of the product from a latex that may be encountered using emulsion polymerization techniques, the heat of reaction is more readily removed as compared to bulk polymerization procedures and no solvent recovery is needed as in solution polymerization.

Generally, the suspension polymerization reaction mixtures comprise from 20 to 45 %, by weight, based on the amount of water, of the above-enumerated monomers in an aqueous reaction medium. Also included will be from 0.05 to 5%, by weight, based on the weight of monomers, of a suspending agent, such as methyl cellulose, hydroxypropyl methyl cellulose or gelatin; from 0.005 to 1%, by weight, based on the amount of monomer, of at least one monomer-soluble initiator, such as azobisisobutyronitrile, lauroyl peroxide, benzoyl peroxide or isopropyl peroxydicarbonate. The polymerization reaction may be conducted by heating the suspension containing the above components to a temperature of from 35 to 75"C. for from 2 to 12 hours with agitation being applied throughout the course of reaction.

As is well known in the art, the use of the more active of the above-mentioned initiators will require use of either a lower temperature or shorter reaction time, or both, while use of the less active initiators may require more vigorous reaction conditions. If desired, the molecular weight of the polymers may be regulated by adding an effective amount of a chain-transfer agent during the polymerization. Generally, from 0.01 to 0.1%, by weight based on the monomers will be effective. Representative chain-transfer agents include the chlorinated hydrocarbons, e.g. tetrachloroethane, trichloroethane and carbon tetrachloride, and mercaptans corresponding to the following general formula: RSH, wherein R represents alkyl, e.g.

C1-C12 alkyl, such as butyl or dodecyl.

If emulsion polymerization is to be employed, the above-described suspending agent is replaced by, e.g., from 0.2 to 2%, by weight, of an emulsifying agent, such as sodium lauryl sulphate, potassium stearate, an alkyl benzene sulphonate or an ammonium dialkyl sulphosuccinate, and the monomer-soluble initiator is replaced by, e.g., from 0.1 to 1% of a water-soluble initiator, such as an alkali metal persulphate, perborate or peracetate, ammonium persulphate, perborate or peracetate, urea peroxides, hydrogen peroxide or tertiary butyl hydroperoxide. If desired, a redox initiator system, such as ammonium persulphate and sodium bisulphite or hydrogen peroxide and ascorbic acid, may also be used as the initiator. Polymerization may be carried out at similar temperatures and over similar times as those which may be used in suspension polymerization.

If bulk polymerization is employed, the monomers may be polymerized in the presence of the above-described amounts of the monomer-soluble catalysts under the same temperature and time conditions described above in connection with suspension and emulsion polymerization.

If solution polymerization is employed, the monomers are polymerized in the presence of at least one inert organic solvent, such as butane, pentane, octane, benzene, toluene, cyclohexanone, acetone, isopropanol or tetrahydrofuran. The selected initiator should be soluble in the reaction medium. The copolymer may either remain dissolved in the solvent at the end of the polymerization or may precipitate from the liquid phase during the polymerization. In the former case, the product may be recovered by evaporation of the solvent or by precipitation of the polymer solution by combining it with a non-solvent for the product. The same reaction conditions used in suspension and emulsion polymerization may be used.

The final product may contain, if desired, various optional additives which are compatible with the copolymer product and which do not adversely affect the properties of the product.

Such additives include heat and light stabilizers, ultra-violet stabilizers, pigments, fillers and dyes known to those skilled in the art. A list of possible additives which one skilled in the art may use to select appropriate additives, if desired, is given in Modern Plastics Encyclopedia, Vol. 51, No. 10A, e.g., at pp. 735-754.

EXAMPLE l This Example illustrates the general procedure which was used to form an internally plasticized resin in accordance with the present invention by suspension polymerization.

The following ingredients were used. All amounts are given in parts, by weight: Ingredient Amount vinyl chloride monomer 100 2ethylhexyl acrylate 46.5 bis(b eta-chloroethyl) vinylphosphonate 19.95 hydroxypropylmethylcellulose suspending agent ("Methocel" (Registered Trade Mark) K-35 from The Dow Chemical Co.) 0.23 20 wt. % isopropylperoxy dicarbonate in heptane 0.54 deionized water 423 The following procedure was used to polymerize the vinyl chloride, acrylate and vinylphosphonate monomers: 1. The suspending agent was dissolved in a portion of the deionized water and was charged into the reactor along with the remainder of the deionized water. The mixture was stirred briefly and the peroxydicarbonate/heptane initiator mixture was added; 2. The acrylate and vinylphosphonate monomers were added; 3. The reactor was closed, vacuum was applied (approx. 584.2-635 mm. of Hg. pressure) for 10 minutes to remove air from the reactor and vinyl chloride monomer vapour was added to break the vacuum. This operation was repeated once and the vinyl chloride was charged into the reactor; 4. The agitator was set at 496 revolutions per minute and the reactor was heated to 500C until the pressure in the reactor dropped 4.2 kg./cm2 from the maximum pressure noted near the beginning of the reaction; 5. The reactor was vented and sparged with nitrogen at a rate of 70.7 cubic cm./sec. for a 44 litre reactor for a period of 1 hour to remove residual monomer from the product; 6. The reactor was allowed to cool and the polymer particles were recovered by centrifuging. The particles were dried in a fluid bed drier using air at 30"C.; 7. The dried polymer was milled through a Fitz mill and was sieved through a 30 mesh (U.S.

Standard Sieve) screen.

Three repeats of the above procedure were conducted. The polymers which were obtained contained from 57.4 to 57.7%, by weight, of vinyl chloride, from 29.7 to 31.5%, by wei ht, of 2-ethylhexyl acrylate and from 11.1 to 12.6%, by weight, of bis(beta chloroethyl)vinylphosphonate and a relative viscosity of from 2.74 to 3.07 when measured as a 1 %, by weight, solution of the copolymer in cyclohexanone. The feed composition in each case was a 60/28/12 weight percent composition of each of the respective monomers. The differences were due to minor uncontrollable variations in the above-described reaction conditions.

EXAMPLE 2 The following Example illustrates the physical properties of a series of film formulations made from the copolymer according to the present invention. The following procedures were used to make each test sample: Samples 1 to 3: A compressible film formulation was made for each sample by mixing together the following ingredients in the following amounts: (Amount in Grams) Ingredient 1 2 3 copolymer according to the present invention* 255 255 255 chlorinated polyethylene 45 45 45 epoxidized octyl tallate 15 15 15 barium-cadmium liquid stabilizer 9 9 9 calcium stearate lubricant 3 3 3 stearic acid lubricant 3 3 3 calcium carbonate filler 90 90 90 titanium dioxide pigment 12 12 12 acrylic processing aid ("K-175" sold by Rohm and Haas Co.) 15 ethylene bis-stearamide lubricant ("Lubrol EA" sold by 1. C. I.

Organics, Inc.) 3 3 bis-stearamide lubricant ("Advawax 240" sold by Cincinnati Milacron) --- --- 3 * Sample 1 used a 57.4/31.5/11.1 copolymer of vinyl chloride (VC)/2-ethylhexyl acrylate (EI-IA)/bis(beta-chloroethyl) vinylphosphonate (BB) having a relative viscosity of 2.78. Sample 2 used a 57.6/30.9/11.5 copolymer having a relative viscosity of 3.07. Sample 3 used a 57.7/29.7/12.6 copolymer having a relative viscosity of about 2.8.

The ingredients mentioned in the above formulations were hand-mixed and were then milled on a 2 roll mill having the rolls at 310 F. (154 C.) and 315 F. (157 C.), respectively, for Sample 1 and 157 C. and 320 F. (160 C.) for Samples 2 and 3. After fluxing in the 2 roll mill for about 7 min., the milled stocks were compression moulded at 320 F. (160 C.) to produce films having a thickness of from 0.038 in. (0.09 cm.) to 0.048 in. (0.12 cm.) for measurement of the physical properties according to various standard testing procedures.

Samples 4 to 7: Compressible film formulations were formed from the following ingredients: (Amount in Grams) Ingredient 4 5 6 7 copolymer according to the present invention* 300 300 300 300 epoxidized soybean oil 15 - 15 epoxidized octyl tallate --- 15 --- 15 barium-cadmium stabilizer (liq.) 9 9 9 9 calcium stearate 3 3 3 3 stearic acid 3 3 3 3 bis-stearamide lubricant 3 ethylene bis-stearamide lubricant --- 3 3 3 3 * the copolymer used in Samples 4 and 5 was the same copolymer used in Sample 1, while the copolymer used in Samples 6 and 7 was the same as that used in Sample 2.

The mill conditions for Samples 4 and 5 were the same as for Sample 1, and the conditions for Samples 6 and 7 were the same as for Samples 2 and 3.

Samples 8 to 11: Compressible film formulations were formed from the following ingredients: amount in Grams) Ingredient 8 9 10 11 copolymer according to the present invention* 255 255 255 150 chlorinated polyethylene 45 45 75 150 epoxidized octyl tallate 15 15 15 15 barium-cadmium stabilizer (liq.) 9 9 9 9 calcium stearate 3 3 3 3 stearic acid 3 3 3 3 calcium carbonate 90 90 90 90 titanium dioxide 12 12 12 12 fused silica ("Cab-O-Sil" (Registered Trade Mark)) 3 --- 3 3 3 ethylene bis-stearamide lubricant 3 3 bis-stearamide lubricant - --- 3 3 * the copolymer used in Sample No. 8 was the same as that used in Sample No. 1; the copolymers in Samples Nos. 9 to 11, the same as in Sample No. 2.

Sample No. 8 was milled using the same procedure as that used with Sample No. 1. Samples Nos. 9 to 11 were milled using the procedure for Samples Nos. 2 and 3.

Samples 12 and 13: Compressible film formulations were formed from the following ingredients: (Amount in Grams) Ingredient 12 13 copolymer according to the present invention* 150 150 epoxidized soybean oil 7.5 7.5 calcium carbonate 45 45 titanium dioxide 6 6 calcium stearate 1.5 1.5 stearic acid 1.5 1.5 bis-stearamide lubricant 1.5 1.5 * this consists of 150 grams ofa blend formed by admixing 1970 g of the copolymer used in Sample No. 1, 3988 grams of the copolymer used in Sample No. 2 and 5080 grams of the copolymer used in Sample No. 3.

The samples were milled in accordance to the procedure used to mill Sample No. 1 with the rolls for Sample 12 being at (154/157"C.) and those for Sample 13 at (138/140.5"C.).

Table 1 which follows sets forth the physical properties for these thirteen samples.

TABLE 1 SAMPLE NO.

PROPERTY 1 2 3 4 5 6 7 Clash-Berg Temperature ( C.)1 -27 -30 -28 -23 -28 -28 -37 Shore "A" Hardness2 67 69 64 65 61 68 58 Tensile Strength, Break (kg./cm.2)3 72.1 80.8 63.4 115.6 97.7 106.4 91.5 100% Modulus (kg./cm.2)4 44.5 48.0 37.8 65.4 46.6 55.6 49.3 Elongation at Break (%)5 269 257 279 229 271 231 219 Graves Tear Strength (kg./cm.)6 20.3 23.7 20.1 24.4 19.6 24.8 18.3 Flexural Modulus of Elasticity (kg./cm.2)7 54.1 81.5 49.9 54.8 44.2 84.3 37.9 Hexane Permanence8 --- 4.6 5.5 --- 6.9 6.8 6.6 Perchloroethylene Permanence9 --- 4.5 7.3 --- 8.6 5.0 6.4 % Volatile Weight Loss10 --- 1.0 1.7 1.5 1.8 1.8 1.6 TABLE 1 (continued).

SAMPLE NO.

PROPERTY 8 9 10 11 12 13 Clash-Berg Temperature ( C.)1 -30 -30 -29 -31 --- -- Shore "A" Hardness2 58 69 65 62 76 76 Tensile Strength, Break (kg./cm.2)3 80.2 80.8 62.5 62.0 105.5 106.1 100% Modulus (kg./cm.2)4 36.2 48.0 35.8 26.4 70.0 72.3 Elongation at Break (%)5 311 257 309 523 203 201 Graves Tear Strength (kg./cm.)6 19.8 23.7 23.0 28.3 26.4 24.6 Flexural Modulus of Elasticity (kg./cm.2)7 40.0 81.5 78.7 74.5 147.6 140.6 Hexane Permanence8 --- 4.6 6.0 6.0 --- -- Perchloroethylene Permanence9 --- 4.5 9.3 8.6 --- -- % Volatile Weight Loss10 --- 1.0 1.6 1.3 --- --- Footnotes: 1. This is the temperature at which the apparent modulus of elasticity of a specimen is 9491.4 kg./cm. 2 It is the end of flexibility of the sample as defined by Clash and Berg in their studies of low temperature flexibility. This point may be determined by ASTM D 1043.

2. This is a measure of identation hardness and is measured on the Shore A durometer after 10 seconds (ASTM Test Method No. D-2240). This instrument comprises a spring loaded indentor point with a load of 822 grams projecting through a hole in a presser foot. The device has a scale which indicates the degree of penetration into the plastic beyond the face of the foot. The scale ranges from 0 (for 0.254 cm. penetration) to 100 (for zero penetration).

3. This is the maximum tensile stress sustained by a specimen of the resin during a tension test (ASTM D-882). The result is expressed in kilograms per cm.2, the area being that of the original specimen at the point of rupture rather than the reduced area after break.

4. This is the tensile strength needed to elongate a specimen to 100% of its original length (ASTM D-822).

5. In tensile testing elongation is the increase in length of a specimen at the instant before rupture occurs (ASTM D-882). Percent elongation is expressed as the increase in distance between two gauge marks at rupture divided by the original distance between the marks, the quotient being multiplied by 100.

6. The Graves test (ASTM) was used to determine the tear strengths using specimens from 0.10 to 0.127 cm. in thickness.

7. The ratio of stress (nominal) to corresponding strain below the proportional limit of a material (ASTM-790). It is expressed in force per unit area.

8. Measured at room temperature after 24 hours. The films were kept in hexane at room temperature for 24 hours, followed by oven drying in a forced air oven at 500C. for 3 to 4 hours. The numbers give the percent weight loss of extractibles in the film. Low numbers are desirable.

9. Measured at room temperature after 1 hour. The films were kept in perchloroethylene for 1 hour, followed by drying in a forced air oven at 500C. for 5 hours. The numbers give the percent weight loss of extractibles in the film. Low numbers are desirable.

10. The films were placed in a container containing activated carbon and were heated at 90"C. for 24 hours. The volatile materials were absorbed by the carbon. The numbers represent the percent volatile weight loss from the film. Low numbers are desirable.

Samples 1 to 3 which are the internally plasticized resins according to the present invention are all fairly alike in physical properties. Resin No. 3 is slightly softer than the first two resins.

Samples 4 to 7 show the effects that the addition of two epoxy stabilizers has on Resin Nos.

1 and 2. The epoxidized octyl tallate reduces the low temperatures flexibility by from 5 to 7"C. at a concentration of 5 parts per hundred (based on 100 parts of resin) as compared to the epoxidized soybean oil. However, the use of the tallate additive affects the physical properties, e.g. lowers the hardness of the films, as well as the tensile and tear strengths. The presence of these epoxy stabilizers increases both the light and heat stability of the resin.

Samples 8 to 11 show the effect of addition of chlorinated polyethylene to the resin and should be compared to Sample 5 as a control. In general, addition of as low as 15 %, by weight, of chlorinated polyethylene improves the elongation with only a slight reduction of other desired characteristics.

Samples 12 and 13 illustrate the physical property data for the internally plasticized resin according to the present invention processed at two different temperatures. The properties are essentially the same, which would allow those skilled in the art to use the lower temperature.

Example 3 The following Example illustrates the mill heat stability of various internally plasticized resins in accordance with the present invention.

Compressible film formulations were formed from the following ingredients for each of the enumerated samples: (Amount in Grams) Ingredient 1 2 3 4 5 copolymer according to the present invention* 170 85 85 170 170 chlorinated polyethylene 30 15 15 30 30 epoxidized octyl tallate 10 5 5 10 10 barium cadmium stabilizer (liq.) 6 ~~ --- 6 6 calcium stearate 2 1 1 2 2 stearic acid 2 1 1 2 2 calcium carbonate 60 30 30 60 60 titanium dioxide 8 4 4 8 8 bis-stearamide lubricant 2 1 1 2 2 barium-cadmium-zinc-stabilizer --- 3 3 phosphite chelator ("Mark C" sold by Argus @@emical) --- 1 1 --- 2 * the copolymer used in Samples 1 to 3 is the same as that used in Samples Nos. 12 and 13 from above. The copolymer used in Sample No. 4 was the same as that used in Sample No. 1 from Example 2 above. The copolymer used in Sample No. 5 was a 59 VC/28 EHA/12 BB copolymer having a relative viscosity of about 2.86.

Table 2 below gives the processing temperatures in the 2 roll mill, the type of stabilizer system that was used and comments on the appearance of the film.

TABLE 2 Sample Processing1 Stabilizer System2 Comments No. Temperature 1 121/124 C Ba-Cd: 3phr After 160 minutes of processing, there epoxy 5phr was substantially no film colour development compared to the initial film colour after 10 minutes.

2 138/141 C Ba-Cd-Zn: 3phr After 160 minutes of processing, there epoxy: 5phr was substantially no film colour phosphite chelator: 1phr development compared to the initial film colour after 10 minutes.

3 157/160 C Ba-Cd-Zn: 3phr At about 90 minutes, the film surface epoxy: 5phr became rough and a very slight yellow phosphite chelator: 1phr colour developed.

4 157/160 C Ba-Cd: 3phr At about 80 minutes, the film surface epoxy: 5phr became rough with a slight evelopment of yellow colour 5 157/160 C Ba-Cd: 3phr At about 90 minutes, the film surface epoxy: 5phr became rough with slight developm Footnotes: 1. The milling was carried out on a two roll mill operated at the temperature values set forth in Table 2. The temperature before the oblique refers to the front roll, while the one after the oblique the back roll.

2. "Ba-Cd" and "Ba-Cd-Zn" stand for barium-cadmium and barium-cadmium-zinc heat stabilizers, respectively. The "epoxy" stabilizers used were epoxidized soybean oil and epoxidized octyl talate. The phosphite chelator is available commercially as "Mark C" from the Argus Chemical Co. All parts per hundred (phr) are based on the resin as 100 parts, by weight.

Example 4 The following Example gives the results of smoke measurement tests conducted in a commercial smoke density chamber modelled after one developed at the National Bureau of Standards by the Fire Research Group (See D. Gross, J. J. Loftus and A. F. Robertson, ASTM Special Technical Publication 422, pages 166-204, 1969). This chamber contains a radiant heater producing 2.5 W/cm.2 of heat at the surface of a 7.62 cm. x 7.62 cm. sample, a propane-air pilot burner and a vertical beam of light with a photomultiplier tube detector and microphotometer to record the attenuation of light by smoke developing in the chamber.

During smoke testing, the chamber is sealed to enclose the combustion products and smoke.

The tests were conducted under the smouldering mode (Table 3), as well as the flaming mode (Table 4). The values shown in parenthesis are from duplicate runs.

TABLE 3 Dm/Gm6 FR Dm - MAXIMUM4 Dm/Gm of5 OF ADDITIVE WEIGHT OF SPECIFIC OPT. ORIGINAL MASS SAMPLE DESCRIPTION (PHR) SAMPLE (grams) DENSITY SAMPLE LOSS LOI7 PVC + 55 phr dioctyl phthalate1 None 2.1 126 60 140 21.4 PVC + 55 phr dioctyl phthalate Sb2O3 2.5 140 56 128 27.1 (5) (142) Internally Plasticized Resin2 None 2.7 53 19 50 22.2 (2.9) (52) (18) (36) Internally Plasticized Resin2 Sb2O3 3.0 37 12 29 28.4 (5) (3.4) (53) (15) (34) Internally Plasticized Resin3 None 2.4 51 21 43 23.3 (2.7) (52) (19) (41) Internally Plasticized Resin3 Sb2O3 2.5 40 16 32 28.6 (5) (2.8) (45) (16) (32) TABLE 4 Dm/Gm FR Dm=MAXIMUM Dm/Gm OF OF ADDITIVE WEIGHT OF SPECIFIC OPT' ORIGINAL MASS SAMPLE DESCRIPTION (phr) SAMPLE (grams) DENSITY SAMPLE LOSS PVC + 55 phr dioctyl None 1.9 117 61 105 phthalate1 (2.0) (117) (58) (94) PVC + 55 phr dioctyl Sb2O3 2.5 195 78 135 phthalate (5) (2.5) (168) (67) (110) Internally Plasticized None 3.2 125 39 78 Resin2 (2.7) (124) (46) (83) Internally Plasticized Sb2O3 3.4 138 40 73 Resin2 (5) (3.4) (144) (42) (78) Internally Plasticized None 2.5 88 35 68 Resin3 (2.2) (99) (45) (82) Internally Plasticized Sb2O3 2.9 110 37 81 Resin3 (5) (2.6) (114) (43) (77) Footnotes: 1. The polyvinyl chloride (PVC) resin is a high molecular weight PVC resin developed for calendered goods applications and is available commercially as "SCC-686" from Stauffer Chemical Company, Plastics Division. The dioctyl phthalate (an external plasticizer) is available under the tradename "6-10 Phthalate" from Hatco Chemicals.

2. The copolymer according to the present invention. This particular example contained the same copolymer that was used in above Example 2, Sample Nos. 12 and 13.

3. Another copolymer according to the present invention. This particular sample contained a 63.4 VC/ 27.4 EHA/ 9.2 BB copolymer having a relative viscosity of 2.89.

4. The maximum specific optical density gives a measure of the smoke build-up during the test. Lower numbers indicate less obstruction of light due to smoke and are preferred.

Dm=25, light smoke; 25-75 moderate smoke; 100-400, dense smoke; 400, very dense smoke.

5. This gives a corrected value for the maximum smoke generation per unit weight of sample. Low numbers are desirable.

6. This value represents the smoke generation per unit weight of material consumed during the burning process. Low numbers are again desirable.

7. This is an abbreviation for the Limiting Oxygen Index and is defined as the minimum mole percent 2 content required in an oxygen/nitrogen mixture to maintain combustion of a vertical, top-lighted test specimen. High numbers are indicative of a more fire retardant material.

Analysis of the data presented in Tables 7 and 8 shows that under smouldering conditions, a film of the internally plasticized resin according to the present invention containing no fire retardant additives produces approximately 65-68% less smoke compared to a similar externally plasticized film whether or not these data are based on unit mass of the original sample tested or unit mass of the original sample consumed during the testing process.

Similarly, again under smouldering test conditions, a similar film containing a fire retardant additive produces even better smoke reduction (e.g., 78% reduction) compared to an externally plasticized film containing a similar fire retardant additive. Under flaming modes of burning, the internally plasticized films according to the present invention again show less smoke generation as compared to externally plasticized film, i.e., approximately 30%less for films containing no fire retardant additives and approximately 50% for films containing fire retardant additives and approximately 50% for films containing fire retardant additives.

EXAMPLE 5 This Example illustrates the general procedure which was used to form an internally plasticized resin having a higher vinyl chloride content than the copolymer formed in Example 1 and to blends of this copolymer with another internally plastized polymer.

The following ingredients were used. All amounts are given in parts, by weight: Ingredient Amount vinyl chloride monomer (VCM) 50 lbs. 13l/2 oz.

2-ethylhexyl acrylate (2-EHA) 11 libs. 9 oz. bis(beta-chloroethyl) vinylphosphonate (BB) 4 Ibs. 12 oz. methylcellulose suspending agent ("Methocel" 1242 from The Dow Chemical Co.) 30 grams 20 wt. % isopropylperoxy dicarbonate in heptane 85 grams deionized water 74.85 kg.

The following procedure was used to polymerize the vinyl chloride, acrylate and vinylphosphonate monomers: 1. The suspending agent was dissolved in a portion of the deionized water and was charged into the reactor along with the remainder of the deionized water. The mixture was stirred briefly and the peroxydicarbonate/heptane initiator mixture was added; 2. The acrylate and vinylphosphonate monomers were added; 3. The reactor was closed, vacuum was applied (approx. 584.2-635 mm. of Hg . pressure) for 10 minutes to remove air from the reactor, and vinyl chloride monomer vapour was added to break the vacuum. This operation was repeated once and the vinyl chloride monomer was charged into the reactor; 4. The agitator was set at 351 revolutions per minute and the reactor was heated to 500C. until the pressure in the reactor dropped 4.2 kg./cm. 2 from the maximum pressure noted near the beginning of the reaction: 5. The reactor was vented and sparged with nitrogen at a rate of 70.7 cubic cm./sec. for a 44 litre reactor for a period of 1 hour to remove residual monomer from the product; 6. The reactor was allowed to cool and the polymer particles were recovered by centrifuging. The particles were dried in a fluid bed drier using air at 30"C; 7. The dried polymer was milled through a Fitz mill and was sieved through a 30 mesh screen > (U.S. Standard Sieve).

The resin that was produced from the 76% VC/ 17.3% 2-EHA/ 6.7% BB feed composition had a 73.6% VC/ 18.2% 2-EHA/ 8.2% BB composition and a relative viscosity of 2.72 when measured at 250 C. as a 1%, by weight, solution of the copolymer in cyclohexanone.

This resin and combinations of the resin with the 57.4%VC/31.5%2-EHA/11.1%BB resin from above Example 2 (Samples 12 and 13) were fabricated into film-forming compositions by mixing together the following ingredients in the following amounts: (Amount in Grams) Ingredient 1 2 3 copolymer of Example 2 (Samples 12 and 13) - 70 60 copolymer of Example 5 100 30 40 epoxidized soybean oil 5 5 5 barium-cadmium liquid stabilizer 3 3 3 phosphite chelator ("Mark C", sold by Argus Chemical Corp.) 1 1 1 calcium stearate 1 1 1 stearic acid 1 1 1 bis-stearamide lubricant 1 1 1 calcium carbonate filler 30 30 30 titanium dioxide pigment 4 4 4 The above formulations were calendered into a film on a 2 roll mili 310/315"F.(154/1 57"C.) for all samples, at 30/42 rpm after all ingredients had been mixed and fluxed for about 7 minutes. The samples were compression moulded at 3200F. (160"C.) to produce films having a thickness of from 0.09 to 0.12 cm. The Table which follows sets forth the physical properties of the samples that were tested.

SAMPLE NO.

1* 2** Clash Berg Temperature (OC) -4 -19 -16 Shore "A" Hardness 95 84 86 Tensile Str. at Break (kg./cm.2) 155.6 108.9 106.2 100% Modulus (kg./cm.2) 148.4 94.4 98.1 Elongation of Break (%) 135 153 135 Graves Tear Strength (kg./cm.) 52.2 29.5 32.4 Flexural Modulus of Elasticity (kg./cm.2) 630.6 261.8 197.5 * The copolymer used in this sample is a copolymer formed in accordance with Example 5.

** The copolymer used in this sample is a blend of 70%, by weight, of the copolymer from above Example 2 (Samples 12 and 13) and 30%, by weight, of the copolymer from Example 5.

*** The copolymer used in this sample is a blend of 60% of the copolymer from above Example 2 (Samples 12 and 13) and 40% of the copolymer from Example 5.

The data presented in the preceding Table illustrate that a variation of the physical properties and hardness of the flexible vinyl films may be achieved by incorporating the "hard' and "soft" embodiments of the present copolymer films in varying ratios in the formulations.

For comparison purposes only, the following illustrates that use of alkyl acrylate comonomers having alkyl groups that contain less carbon atoms than specified for the acrylates used herein do not function as internally plasticized resins as that term is used herein.

The terpolymers listed in the Table which follows were formed by suspension polymerizing the ingredients also listed in the Table for 13 hours at about 46"C. All amounts are given in parts, by weight, using as the initiator 10%, by weight, of isopropylperoxydicarbonate in heptane and hydroxypropylmethylcellulose (1%, by weight, solution) as the suspending agent.

TABLE INGREDIENTS* (parts, by weight) TERPOLYMER* H2O Susperd. BB BA EA Chain Initiator VCM Agent Transfer** Agent 1. 65% VC/20% BA/15% BB 350 45 15 20 -- 0.05 2.5 65 2. 81% VC/ 5% BA/14% BB 350 45 14 5 -- -- 2.5 81 3. 40% VC/20% EA/40% BB 350 45 40 -- 20 -- 2.5 40 4. 60% VC/20% EA/20% BB 350 45 20 -- 20 -- 2.5 60 5. 60% VC/30% EA/10% BB 350 45 10 -- 30 - 2.5 60 6. 75% VC/10% EA/15% BB 350 45 15 -- 10 -- 2.5 75 * the abbreviations are as follows3/4 BB = bis(beta-chloroethyl)vinylphosphonate; BA = butyl acrylate; VCM = vinyl chloride monomer; EA = ethyl acrylate. The weight amounts of reactants for terpolymer Nos. 1 and 2 were reacted in each of four bottles and the product from each was combined. The weight amounts for the reamining terpolymers were each reacted in a single bottle.

** the chain transfer agent was 0.05 ml. of t-dodecyl mercaptan.

Each of the termpolymers set forth in the preceding Table was then formed into compressible film formulations using the procedures described in above Example 2 using the following ingredients. All amounts are given in parts by weight.

Ingredient Amount terpolymer resin 100 epoxidized soybean oil ("G-62", sold by Rohm and Haas Co.) 5 barium-cadmium powder stabilizer ("V-1541", sold by Tenneco Chemicals, Inc., Intermediates Div.) 1.5 phosphite chelator stabilizer ("V-1542", sold by Tenneco Chemicals, Inc., Intermediates Div.) 1.5 calcium stearate lubricant 0.5 stearic acid lubricant 0.5 Each product was then tested for the various physical properties reported in the Table which follows: TABLE SAMPLE NO.

1 2 3 4 5 6 Clash-Berg Temperature ("C) NA NA O NA NA NA Shore "A" Hardness 98 96 72.5 90 99 96 Tangent Modulus of 1212.4 11,139.9 23.0 1328.2 1722.2 9431.1 Elasticity (kg/cm2) Tensile St., Break 182.3 14.1 108.1 242.0 237.7 60.3 (kg/cm2 ) %Elongation, Break 103 0 215 67 83 0 Secant Modulus at 100% NA NA 92.2 NA NA NA Elongation (kg/cm2) Note: For those films for which "NA" appears for the Clash-Berg value, they were judged to be physically more rigid than Sample No. 3 and hence would have a Clash-Berg value above 0 C. This value was not experimentally determined for these samples. Of all the samples tested, only Sample No. 3 showed some degree of flexibility.

Secant modulus is the ratio of total stress to corresponding strain at a specified point in the stress-strain curve. It is expressed as force per unit area with higher numbers generally indicating more rigid materials.

Tangent modulus is the slope of the line at any point on a static stress-strain curve expressed as force per unit area. Where "NA" appears, it indicates that the value could not be obtained since the sample broke before 100% elongation was reached, or in the case of Sample No. 1, the value was not measured. Higher values also generally indicate a more rigid sample.

The data which are presented in the preceding Table illustrate that use of the lower alkyl acrylates (for example, the C2 or C4 alkyl acrylates) in a terpolymer of vinyl chloride and a bis(hydrocarbyl)vinylphosphonate does not yield an internally plasticized resin, as does use of the higher alkyl acrylates (for example, the C8 alkyl acrylates), as contemplated by the present invention.

Claims (16)

WHAT WE CLAIM IS:

1. An internally plasticized copolymer which comprises: (a) from 50 to 85%, by weight, of vinyl chloride; (b) from 3 to 47%, by weight, of C6-C10 alkyl acrylate; and (e) from 3 to 47%, by weight, of bis(hydrocarbyl)-vinylphosphonate (as hereinbefore defined).

2. A copolymer as claimed in claim 1 comprising, as (a) from 55 to 80%, by weight, vinyl chloride.

3. A copolymer as claimed in claim 1 or claim 2 comprising, as (b) from 10 to 35%, by weight, C6-C10 alkyl acrylate.

4. A copolymer as claimed in any of claims 1 to 3 comprising, as (c) from 5 to 25 %, by weight, bis(hydroearbyl)vinylphosphonate.

5. A copolymer as claimed in any of claims 1 to 4 comprising, as (c), a bis(C1-C8 alkyl or haloalkyl)vinylphosphonate.

6. A copolymer as claimed in any of claims 1 to 5 comprising, as (c), bis(betachloroethyl)- vinylphosphonate or bis(2-ethylhexyl) vinylphosphonate.

7. A copolymer as claimed in any of claims 1 to 6 comprising, as (b), a C8-C10 alkyl acrylate.

8. A copolymer as claimed in claim 7 comprising, as (b), 2-ethylhexyl acrylate.

9. A copolymer as claimed in any of claims 1 to 8 comprising: (a) from 56 to 58% of vinyl chloride; (b) from 29 to 31%, by weight, of C6-C10 alkyl acrylate; and (e) from 11 to 13%, by weight, of bis(beta-chloroethyl)vinylphosphonate.

10. A copolymer as claimed in any of claims 1 to 8 comprising: (a) from 73 to 75%, by weight, of vinyl chloride; b from 17 to 19%, by weight, of C6-C10 alkyl acrylate; and (c) from 7 to 9% by weight, of bis(beta-chloroethyl)vinylphosphonate.

11. A copolymer as claimed in claim 1 substantially as herein described.

12. A copolymer as claimed in claim 1 substantially as herein described with reference to any one of the Examples.

13. A process for the preparation of a copolymer as claimed in claim 1 which comprises copolymerizing the monomers (a), (b) and (c) by bulk, emulsion, suspension or solution polymerization.

14. A process as claimed in claim 13 substantially as herein described.

15. A process as claimed in claim 13 substantially as herein described with reference to either of Examples 1 and 5.

16. A copolymer as claimed in claim 1 when prepared by a process as claimed in any of claims 13 to 15.