ANTISTATIC PLASTIC MATERIALS CONTAINING EPIHALOHYDRIN POLYMERS

Abstract: Thermoplastic and thermoset materials containing an effective amount of an antistatic agent for improving antistatic properties thereof, the antistatic agent is selected from homopolymers and copolymers of an epihalohydrin.

Description: When formed into such articles as molded objects or films, synthetic polymers are known to generate and accumulate electrostatic charges. When charged, such objects tend to accumulate concentrations of dirt and soil which are unsightly in appearance and interfere with the use of such objects. When nylon or polyester polymers are formed into fibers, the electrostatic charges create processing problems whereas in consumer use, carpeting made from such synthetic fibers has a tendency to generate annoying shocks in cold, dry weather, while in apparel, the charged fabric clings embarassingly to the wearer and shocks the wearer when the garment is being removed. Furthermore, such garments have an increased tendency to attract lint and soil. The problem of electrostatic charge and arcing that it can create, is also of great concern in clean rooms, such as hospital surgery rooms, as well as chemical plants and laboratories, and electronic equipment, in particular. Arcing due to an electrostatic charge can cause an explosion or can damage electronic equipment. To overcome the static electricity problem, topical antistats have been used to eliminate the electrical charges, however, such treatments have proven to be of little benefit in the consumer applications due to lack of permanency. Other methods used to reduce the electrostatic charges included copolymerization of monomers containing ionizable groups, surface grafted polymerization of antistatic monomers, inclusion of metallic fibers or carbon-coated filaments, incorporation of an antistatic additive in the matrix polymer, and the like. The prior art is replete with teachings to reduce antistatic charges in various polymeric structures. Certain prior art patents describe the incorporation of antistatic materials in various polymeric structures which are used to mold or extrude rigid objects such as luggage, protective covers, and automobile parts. There is also a vast body of prior art patent literature directed to the elimination of the static charges in fiber and films. Item #2 is a report which is not published, dated July 23,1970 by R.J. Meyer and C.V. Purks entitled "Evaluation of Hydrin as a Rigid PVC Additive". This report discloses that Max Roha, then an employee of The B.F.Goodrich Company, on a trip to Europe was informed that Wacker Chemie GMBH in West Germany was adding Herclor® C resin to rigid PVC to improve impact strength and to impart antistat characteristics. Herclor C is similar to Hydrin 200, i.e., a copolymer of epichlorohydrin and ethylene oxide in the weight ratio of about 60-70/40-30. This report discusses results of tests conducted on the use of Hydrin 100, a homopolymer of epichlorohydrin, and Hydrin 200, a copolymer of epichlorohydrin. More recently, certain technical literature was mailed with our knowledge to Hydrin polymer customers. This literature, which is denoted as items #5 and #6 herein, was mailed to the customers in about the first or second quarter of 1984. Item #5 is entitled "Hydrin Rubber As A Flexible PVC Antistat" whereas item #6 is entitled "Hydrin Rubber As A Rigid Vinyl Antistat". Both of these items report test data on rigid and flexible PVC containing varying amounts of Hydrin materials along with physical properties, including static electrical tests. This invention is directed to a polymeric antistatic additive in solid form, composed of the copolymerization product of a) at least 10 but less than 40 weight parts epihalohydrin; and b) more than 60 and up to 90 weight parts ethylene oxide, propylene oxide or mixtures thereof, on a total of 100 weight parts basis of said copolymer. An effective amount of the antistatic agent is used in the plastic material to induce charge dissipation by at least 50% in less than 10 seconds on application of 1000 volts of direct current at 23.5°C and 50% RH. More specifically, the electrostatic agent can be used in amount of 1 to 50 weight parts, preferably 2 to 30 weight parts, per 100 weight parts of the plastic material. Examples of thermoplastic materials include polymers of acrylonitrile, butadiene, and styrene, also known as ABS polymers; polyamides or nylons; polyesters; polyvinyl chloride; chlorinated polyvinyl chloride; and polycarbonates. Examples of thermosetting materials include epoxy and phenolic resins. The antistatic agent in solid form, such as powder, is mixed with the plastic material until it is uniformly distributed throughout the plastic material. It should be apparent that the antistatic agent becomes an integral part of the plastic material after it is molded, however, it can also be used as a surface treatment therfor. The polymerization products of the invention are readily prepared by polymerization in mass or solution with catalysts normally formed by reacting an organoaluminum compound with water, and optionally, with a small amount of a chelating agent. These copolymers normally have a number average molecular weight greater than about 30,000, preferably in excess of 60,000, as determined by gel permeation chromatography. US-A- 4,251,648 describes such solid polymers of epihalohydrin also containing an unsaturated epoxy comonomer which makes it possible to cure such copolymers with an organic peroxide. The epihalohydrin monomers useful in preparing polymeric epihalohydrin antistatic agents of this invention include epichlorohydrin, epibromohydrin, epiiodohydrin, and epifluorohydrin, although eipchlorohydrin is preferred. The antistatic agents include the epihalohydrin copolymers with one or more comonomers selected from ethylene oxide and propylene oxide. The presence of an epihalohydrin in the antistatic agent appears to improve compatibility between the antistatic agent and the plastic material with which it is blended. Other antistatic agents can also be included in the plastic compositions, along with the antistatic agents already described. Some examples of such other antistatic agents include long chain and ethoxylated amines and amides, and quarternary ammonium salts. Many of plastic materials described above are commercial and are readily available. They can be modified by incorporating therein an effective amount of an antistatic agent in order to impart thereto antistatic character, as well as other conventional additives. Such modified plastic materials can then be used to make a great variety of articles such as carpeting, luggage, protective covers, automobile parts, and the like. In preparing samples for testing in examples that follow, a Brabender mixer with a cam head was used. The maximum temperature used for the various plastic materials was as follows: ABS - 180°C PVC - 160°C CPVC - 180°C SAN® - 180°C Example 1 This example demonstates the incorporation of antistatis agents Homopolymer ECH and Copolymer ECH 65/35 and Copolymer ECH 20/80 into a chlorinated PVC, styreneacrylonitrile, and ABS plastic materials. Copolymer ECH 65/35 is a copolymer of epichlorohydrin and ethylene oxide in respective weight ratio of 65/35, with a Tg of -42°C, chlorine content of 25%, and Mooney viscosity of 90 (1+4 @ 100°C). Copolymer ECH 20/80 is a copolymer of epichlorohydrin and ethylene oxide in the respective weight ratio of 20/80 having Tg of -52°C and chlorine content of 9.0%. The chlorinated PVC (CPVC) used had chlorine content of 67%; the styrene-acrylonitrile (SAN) plastic material used was SAN 880; and the ABS plastic material was a copolymer of acrylonitrile, butadiene, and styrene identified as Blendix 131. The samples of the thermoplastic materials, referred to above, were prepared by blending same with the antistatic polymeric agents and the samples were then tested. The samples #1 to #6 were prepared by initially adding the plastic material to the mixer and mixing it for one minute followed by addition of the antistatic agent, which was followed by additional mixing of two minutes. Processing aids were also admixed, where indicated. The soft plastic mass was then removed and cold-pressed between chrome steel plates to a thickness of about 2 millimeters until it was rigid. Testing was conducted with a Monroe #276A Statotester whereas other tests were run pursuant to the ASTM methods. Compositions of test samples and test results are summarized in Table I, below: Example 2 This example demonstrates the importance of the amount of antistatic agent incorporated into ABS plastic material. Copolymer ECH 20/80 and ABS plastic materials are described in Example 1. The samples of ABS plastic materials were prepared by blending same with the antistatic polymeric agent and the samples were then tested in the manner described in Example 1. Composition of the test samples and test results are given in Table II. Example 3 This example demonstrates the incorporation of antistatic agents copolymer EBH, Copolymer ECH-PO 37/63 and copolymer ECH-PO 23/77 into an ABS plastic material described in Example 1. Copolymer EBH is a copolymer of epibromohydrin and ethylene oxide in the respective weight ratio of 15/85 having bromine content of 8.6 wt.%. Copolymerw ECH-PO 37/63 and 23/77 are copolymers of epichlorohydrin and propylene oxide in the respective weight ratios of 37/63 and 23/77 having respective chlorine contents of 14.3% and 8.9% on weight basis. The samples of ABS plastic materials were prepared by blending same with the antistatic polymeric agents and the samples were then tested in the manner described in Example 1. Composition of the test samples and test results are given in Table III. Example 4 This example demonstrates the use of antistatic agents described herein in two commercial polyamide resins identified as Nylon Capron 5526 and Nylon Capron 5556, and an epoxy resin with an EEW of 190. The polyamide resins are examples of thermoplastic materials whereas the epoxy resin is an example of thermosetting materials. The antistatic agent was Copolymer ECH 20/80, earlier identified as a 20/80 copolymer of epichlorohydrin and ethylene oxide. Composition of test samples and test results are summarized in Table IV below.

Claims: A polymeric antistatic additive in solid form, composed of the copolymerization product of a) at least 10 but less than 40 weight parts epihalohydrin; and b) more than 60 and up to 90 weight parts ethylene oxide, propylene oxide or mixtures thereof; on a total of 100 weight part basis of said copolymer.

Inventors: BARNHOUSE, JAMES PATRICK, YU, SIMON HSIAO-PAO
Applicants: THE B.F. GOODRICH COMPANY
Application year: 1986
Main classification: C08G65
IPC codes: C08L55, C08L101, C08L23, C08L67, C08L51, C08L71, C08L63, C08L1, C08L21, C08L27, C08L77, C08L7