Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2355/00—Characterised by the use of homopolymers or copolymers, obtained by polymerisation reactions only involving carbon-to-carbon unsaturated bonds, not provided for in groups C08J2323/00 - C08J2353/00
  • C08J2355/02—Acrylonitrile-Butadiene-Styrene [ABS] polymers

Definitions

• ABSTRACT OF THE DISCLOSURE The surfaces of an acrylonitrile-butadiene-styrene (ABS) article are refinished by penetrating a quantity of solvent through an oxide coating thereon to dissolve a portion of the underlying plastic and thereby remove the oxide coating. An additional quantity of solvent, now containing dissolved plastic, is absorbed into the newly uncovered surfaces which are then dried to evaporate the solvent and to redeposit the dissolved plastic. The article is then heat treated to relieve stress forces developed in the surfaces during drying.
• ABS acrylonitrile-butadiene-styrene
• This invention relates to a method of refinishing the surfaces of articles made from plastic and, more particularly, to a method of refinishing, to original specifications, the surfaces of an article made from acrylonitrile-butadiene-styrene copolymer. It is an object of this invention to provide an improved method of such character.
• ABS type plastic acrylonitrile-butadicue-styrene
• the surfaces of such exposed telephone articles are stained and minutely cracked by contact therewith of foreign contaminants such as human perspiration, tobacco smoke and cosmetics. Such surfaces are also marred and scratched by engagement therewith of either blunt or sharp objects.
• deteriorated surfaces of an article made from an acrylonitrile-butadiene-styrene copolymer are refinished to original specifications by initially contacting the plastic surfaces to be refinished with an essentially two-stage permeating agent.
• a quantity of the agent, in the first stage penetrates into such surfaces to a depth effective to cause a removal therefrom of a layer of deteriorated surface plastic such that new surfaces are uncovered.
• Another quantity of the agent, in the second stage is absorbed into the uncovered surfaces to a depth effective to cause a partial dissolving of a thin layer of the uncovered surfaces so that a quantity of the agent coating the surfaces contains dissolved plastic.
• the article is dried for a period of time suflicient to allow both an evaporation of the agent coating the surfaces and a redeposition of the dissolved plastic on the surfaces to cause a refinishing thereof.
• suflicient to allow both an evaporation of the agent coating the surfaces and a redeposition of the dissolved plastic on the surfaces to cause a refinishing thereof.
• a substantial development of stress forces is produced in the refinished, high gloss surfaces.
• the article is heated to a temperature below the melting point of the plastic for a period of time sufiicient to relieve the stresses developed in the refinished surfaces such that the surfaces have physical characteristics comparable to the physical characteristics obtained on the surfaces in the initial molding of such plastic.
• this heating period additionally serves to remove virtually all of the remaining agent absorbed in the surfaces which would otherwise eventually escape from the plastic and cause a redevelopment of surface stresses.
• Housings, handles and caps of telephones made from acrylonitrile-butadiene-styrene copolymer are extensively utilized in telephone installations on subscribers premises.
• the surfaces of such articles are slowly oxidized by atmospheric contact therewith. This oxidation is believed to take place at nonreacted carbon double bond sites on the surfaces of the plastic material to cause a resulting cross linking of the extending chain lengths of such a polymerized plastic material. Because of the chemical and physical changes which occur with the oxidation of the plastic material, the surface layer 'of plastic on the exposed telephone articles takes on significantly different chemical and physical characteristics than those which it initially possessed.
• the surface layer of acrylonitrile-butadiene-styrene copolymer is readily attacked by human perspiration, tobacco smoke, cosmetics and the like, to cause a staining and minute cracking of the plastic in the vicinity of the oxidation.
• the oxidized surfaces of the plastic are also susceptible to being marred and scratched by either blunt or sharp objects which come in contact therewith.
• any articles which are to be subjected to the process are preferably washed with detergent, rinsed in water, drained and, if desired, thereafter allowed to dry so that surface dirt is removed therefrom in a standard manner.
• the method is initiated by subjecting the deteriorated surfaces of the articles made from acrylonitrile-butadienestyrene copolymer to a spraying operation wherein a spray of two-stage permeating agent is directed against the surface or surfaces to be refinished.
• a spray of two-stage permeating agent is directed against the surface or surfaces to be refinished.
• the two-stage permeating agent is effective to penetrate through the outer oxidized deteriorated surface layer of the copolymer article. This causes a thin layer of unoxidized plastic immediately under the deteriorated layer to dissolve completely, resulting in the subsequent spray removing the deteriorated layer and exposing a new outer surface.
• the agent is effective to penetrate into and be absorbed by the new outer surface or surfaces uncovered by removal of the deteriorated surface layer of plastic. As will be amplified on hereinafter, it is the latter absorbed solvent which ultimately affects the development of a high gloss on such uncovered surface or surfaces.
• one or more of the following solvents may be used as two-stage permeating agents for the spraying operation: ketones, such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters, such as methyl acetate, ethyl acetate and ethylene glycol monethyl ether acetate; dimethyl formamide; and tetrahydrofurane.
• ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone
• esters such as methyl acetate, ethyl acetate and ethylene glycol monethyl ether acetate
• dimethyl formamide dimethyl formamide
• tetrahydrofurane tetrahydrofurane
• the above listed strong solvents for the ABS type plastic may be diluted to form the permeating agents with one or more of the following diluents: alcohols, such as methanol, ethanol and propanol; others, such as ethyl ether and isopropyl ether; parafiinic and aliphatic hydrocarbons, such as pentane, hexane and heptane; and l,l,l-trichloroethane.
• alcohols such as methanol, ethanol and propanol
• others such as ethyl ether and isopropyl ether
• parafiinic and aliphatic hydrocarbons such as pentane, hexane and heptane
• l,l,l-trichloroethane when dichloromethane is utilized as the strong solvent, the preferred diluent therefore is trichlorotrifiuoroethane.
• the two-stage permeating agent found most effective for the refinishing of articles made from an acrylonitrilebutadiene-styrene copolymer consists essentially of to 100% by volume of the strong solvent dichloromethane and 35 to 0% by volume of the diluent trichlorotrifluoroethane.
• the preferred agent consists essentially of a by volume solution of this strong solvent and the diluent therefor.
• the spray operation with the preferred solvent-diluent solution of 70% by volume of dichloromethane and 30% by volume of trichlorotrifiuoroethane may be carried out for a period of 5 to 40 seconds, preferably 10 to 20 seconds, with the temperature of the solvent or solution being maintained at a temperature of 40 to F., preferably 60 to 70 F.
• the preferred solution is maintained at a temperature of approximately 65 F., 3 to 5 seconds of spraying time are required to allow sufficient penetration of the spray through the oxidized surface layer of plastic to cause the initial removal thereof.
• the solution is absorbed into the newly uncovered surface.
• the absorbed solution is effective to dissolve further a layer of fresh plastic, a portion of which plastic is redeposited in a later step of the method to produce smoothness and gloss characteristic on the refinished articles which are similar to those found on the surfaces of newly molded articles.
• only a relatively short portion of the solution spraying period is required initially to remove the outer oxidized layer of plastic, the major portion of the spraying period being employed to direct the solution against the uncovered surface.
• a sprayed article may be subjected to an optio al step wherein the article is maintained in a substantially saturated atmosphere of the vapors of the preferred solution utilized for the spray.
• the article is held in this atmosphere for a period of time from 5 to seconds, preferably 60 seconds.
• This step allows further absorption of the solution into the newly exposed surface and a resultant further dissolving of fresh plastic in such surface.
• this optional step allows the portion of the solution which the surface retains thereon, but does not actually absorb therein, and which solution contains the dissolved plastic, to disperse uniformly the dissolved plastic as a viscous coating over the surface to be refinished. This coating allows the development, in subsequent steps of the process, of a high gloss refinished surface that is extremely uniform in texture and appearance.
• the article Upon completion of the spraying operation or upon completion of the optional step if it is utilized, the article will have a certain amount of solution which contains the dissolved plastic, coating the surface to be refinished.
• the article after either the spraying operation or the optional step, is subjected to an initial drying operation for a period of 30 to 600 seconds, preferably 120 seconds.
• the drying'medium is air heated to a temperature in the range of 95 to 140 F., preferably 100 to 105 F.
• This drying operation removes from the newly refinished, high gloss surface of the article any unabsorbed solution containing dissolved plastic which remains thereon after having been exposed to either the spraying operation or the latter followed by exposure to the substantially saturated atmosphere.
• the plastic contained therein is redeposited on the surface to refinish the same to the gloss characteristics of the plastic obtained in the initial molding thereof.
• This initial drying operation is also effective to partially remove some of the solution which has been entrapped by the plastic.
• the plastic redeposited to form the refinished surface tends to solidify into a structure which is substantially impervious to the rapid passage of solution therethrough. Therefore, a quantity of the entrapped solution cannot be removed by the initial drying operation. This entrapped solution may, however, escape through such a solidified surface over a prolonged period of time.
• the process was terminated by allowing the articles, after subjection to the initial drying operation, to dry at an ambient temperature for a period of time sufficient to permit handling of such articles without adversely affecting the newly developed surface thereon. It was felt that the solution entrapped below the newly developed surfaces would escape over a prolonged period of time with no detrimental effect to such a surface. However, it was found that articles having newly developed, high gloss surfaces finished only to this point were unsatisfactory when tested under normal use conditions, as such surfaces deteriorated within a relatively short time.
• the surfaces were easily stress cracked; in another, caused by the too rapid escape of entrapped solution as the surfaces were degenerated by appearance of so-called craters over the refinished surfaces.
• the formation of small craters throughout the refinished surface was a completely unexpected phenomena.
• the surface cratering defect starts out as a small pinhole in the surface of the plastic which gradually grows over a period of days or weeks to give the appearance of a crater.
• Many craters in the same area of the refinished surface gives such a surface an appearance similar to the lunar surface. While no absolute theoretical explanation of this phenomena is known at the present time, it appears that the cratering is effected through a localized loss of diluent from the surface which results from the attacking of such surface by the aforementioned foreign contaminants at specific sites on the surface such as scratches or by foreign material embedded in the surface.
• the most economical drying environment that may be utilized is a simple room drying operation. This room drying operation may be carried out in ambient air for a period from 5 to 48 hours, preferably 16 hours. Moreover, it was found that the development of stress forces from the 16th to the 48th hour is relatively minor and almost complete development of stress forces is achieved by the 24th hour. No beneficial result was found by holding the articles in ambient air in excess of 48 hours.
• a moderate drying environment wherein air is heated to a temperature of to F., a reduction in the drying time is realized in that a substantial development of stress forces in the surface of the article is achieved in a shorter period of time.
• the temperature should not be allowed to rise too high. Otherwise, the refinished surface will develop a whitish, hazy appearance commonly called bloom. It is believed that the hazy appearance is a result of rapid heating.
• This heating operation involves a heating period of 30 to 180 minutes, preferably 60 to 120 minutes, in air maintained at a temperature in the range of 140 to 225 F. Although the full heating period may be carried out at a single temperature in the given range, preferably the first 15 minutes of heating is at 140 F. and the balance thereof is at 170 to 175 F.
• This heating operation has been found very effective both to relieve all the stresses developed in the refinished surface and to remove virtually all remaining solution which would eventually escape spontaneously from the plastic. The removal of such solution insures that further development of stresses in the refinished surfaces after such surfaces have been returned to ambient temperature is substantially eliminated.
• the refinished article surface not only had excellent gloss characteristics, but also physical characteristics comparable to thoses found on the surfaces developed in the initial molding of the copolymer.
• the refinished surfaces although attackable by the same materials which attack an originally molded surface, still have the use period expectancy in telephone installations which compare to newly molded articles, and a use expectancy far exceeding that obtained from articles having highly stressed refinished surfaces.
• the spraying operation of the solution of 50% by volume of dichloromethane and 50% by volume 1,1,l-tricloroethane may be carried out for a period of to 40 seconds, preferably to 20 seconds, with the temperature of the solution being maintained at 60 to 90 F., preferably 70 to 80 F.
• the period of time therefore is 5 to L20 seconds, preferably 90 seconds.
• the initial drying operation utilized with the dichloromethane-1,1,l-trichloroethane solution is from 30 to 600 seconds, preferably 120 seconds at a temperature in the range of 105 to 150 F., preferably 105 to 110 F.
• the suitable drying environment used either after the spraying operation or the optional step, may be the same as employed in the first example of the method of this invention.
• the heating operation is then carried out for a period of time from 10 to 180 minutes, preferably 60 to 120 minutes, in air maintained at a temperature in the range of 140 to 225 F., preferably 150 to 160 F.
• a method of refinishing the surface of a plastic article made from an acrylonitrile-butadiene-styrene copolymer which comprises the steps of:
• a quantity of said agent in the first stage, penetrating into the surface to a depth effective to cause a removal therefrom of an outer oxidized layer of plastic so that a new surface is uncovered and another quantity of said agent, in the second stage, being absorbed into said uncovered surface to a depth effective to cause a dissolving of a portion of said uncovered surface so that a portion of said agent coating said surface contains dissolved plastic;
• a method of refinishing surfaces of a plastic article made from an acrylonitrile-butadiene-styrene copolymer which comprises the steps of:
• a method of refinishing surfaces of a plastic article made from an acrylonitrile-butadiene-styrene copolymer which comprises the steps of:
• 6L A method of refinishing surfaces of a plastic article made from an aerylonitrile-butadiene-styrene copolymer as defined in claim 2 wherein said two-stage permeating agent consists essentially of 6-5 to 100% by volume of dichloromethane and 35 to 0% by volume of tricholortrifluoroethane, wherein:
• said contacting operation is a spraying operation carried out for a period of to 40 seconds, with the temperature of said agent maintained at a temperature of 40- to 90 F., wherein;
• said initial drying operation is for a period of 30 to 600 seconds in air heated to a temperature in the range of 95 to 140 F., wherein;
• said moderate drying operation is for a period of 5 to 48 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of 30 to 180 minutes in air maintained at a temperature in the range of 140 to 225 F.
• said contacting operation is a spraying operation carried out fo ra period of 5 to 40 seconds, with the temperature of said agent maintained at a temperature of 40 to F., wherein;
• said article is maintained in said saturated atmosphere of the vapors of said agent for a period of time from 5 to 120 seconds, wherein;
• said initial drying operation is for a period of 30 to 600 seconds in air heated to a temperature in the range of to 140 F., wherein;
• said moderate drying operation is for a period of 5 to 48 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of 30 to 180 minutes in air maintained at a temperature in the range of 140 to 225 F.
• said contacting operation is a spraying operation carried out for a period of 10 to 20 seconds, with the temperature of said agent maintained at a temperature of 60 to 70 F., wherein;
• said initial drying operation is for a period of 120 seconds in air heated to a temperature in the range of to F., wherein;
• said moderate drying operation is for a period of 16 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of 60 to minutes in air maintained at a temperature of F. for the first 15 minutes and thereafter at a temperature in the range of to F.
• said contacting operation is a spraying operation carried out for a period of 10 to 20 seconds, with the temperature of said agent maintained at a temperature of 60 to 70 F., wherein;
• said article is maintained in said saturated atmosphere of the vapors of said agent for a period of 60 seconds, wherein; said initial drying operation is for a period of 120 seconds in air heated to a temperature in the range of 100 to 105 F., wherein;
• said moderate drying operation is for a period of 16 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of 60 to 120 minutes in air maintained at a temperature of 140 F., for the first 15 minutes and thereafter at a temperature in the range of 170 to 175 F.
• said contacting operation is a spraying operation carried out for a period of to 40 seconds, with the temperature of said agent maintained at a temperature of 60 to 90 F., wherein;
• said initial drying operation is for a period of 30 to 600 seconds in air heated to a temperature in the range of 105 to 150 F., wherein;
• said moderate drying operation is for a period of 5 to 48 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of to 180 minutes in air maintained at a temperature in the range of 140 to 225 F.
• said contacting Operation is a spraying operation carried out for a period of 5 to 40 seconds, with the temperature of said agent maintained at a temperature of 60 to 90 F., wherein; said article is maintained in said saturated atmosphere of the vapors of said agent for a period of time from 5 to 120 seconds, wherein;
• said initial drying operation is for a period of 30 to 600 seconds in air heated to a temperature in the range of 105 to 150 F., wherein;
• said moderate drying operation is for a period of 5 to 48 hours in air maintained at ambient temperatures, and wherein;
• said heating operation is for a period of 10 to 180 minutes in air maintained at a temperature in the range of 140 to 225 F.
• said contacting operation is a spraying operation carried out for a period of 10 to 20 seconds, with the temperature of said agent maintained at a temperature of 70 to 80 F., wherein; said initial drying operation is for a period of 120 seconds in air heated to a temperature in the range of 105 to 110 F., wherein;
• said moderate drying operation is for a period of 16 hours in air maintained at ambient temperatures, and wherein;
• a method of refinishing surfaces of a plastic article made from an acrylonitrile-butadiene-styrene copolymer which comprises the steps of:
• a method of refinishing surfaces of a plastic article made from an acrylonitrile-butadiene-styrene copolymer and having a permeable outer oxidized layer of plastic which comprises the steps of:

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)

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Citations (3)

• 1965
  • 1965-10-23 US US504207A patent/US3443008A/en not_active Expired - Lifetime
• 1966
  • 1966-09-28 GB GB43242/66A patent/GB1165176A/en not_active Expired
  • 1966-10-20 DE DE19661620877 patent/DE1620877A1/de active Pending
  • 1966-10-21 BE BE688676D patent/BE688676A/xx unknown

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