Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/34—Applying different liquids or other fluent materials simultaneously
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
  • B05D1/045—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field on non-conductive substrates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/32—Processes for applying liquids or other fluent materials using means for protecting parts of a surface not to be coated, e.g. using stencils, resists
  • B05D1/322—Removable films used as masks
  • B05D1/325—Masking layer made of peelable film

Definitions

• this invention relates to a process for forming a coagulated coating by impinging a stream of a latex and a stream of a coagulant for said latex, at least one of said impinging streams containing a debonding agent, said impingment occurring just prior to or on the surface to be coated, thereby forming an instant coating which coating due to said debonding agent can be readily removed when dseired.
• a permanant protective coating is not permissable.
• coatings on mechanical replacement parts and the like must be capable of being easily stripped from the part before the article can be put to its intended use.
• One object of the instant invention is the application of a coating in a single operation at ambient temperatures without the need for curing. Another object is the application of a coating of substantially uniform thickness to uneven surfaces such as concave and convex surfaces.
• a still further object of the invention is the provision of a coating composition which has low adherence to the substrate coated whereby the film may be readily stripped tom the surface even after extended periods.
• Still another object of the invention is to provide a strippable coating composition which is waterproof, tough and resilient and which has excellent flexibility at very high and low temperatures.
• Another object is to provide a strippable coating composition which affords a film that has good tensile strength.
• Yet another object is to provide a strippable coating composition which may be applied by spraying and without the need for toxic or flammable organic solvents.
• a further object is to provide a strippable coating composition having good resistance to water vapor transmission. Another object is to provide a strippable coating composition having good resistance to outdoor climatic conditions. Yet another object of the invention is to provide a strippable coating composition affording excellent resistance to corrosion of metal substrates.
• a coating formed by impinging two streams the first stream being a latex of a high polymer having positively or negatively charged particles and the second stream being a coagulant, i.e. an emulsion, dispersion or solution of a substance with oppositely charged particles from said latex, either or both of said impinging streams containing therein a minor amount of a debonding agent, said debonding agent thus allowing the coagulated coating to be readily removed from the coated substrate at any time after coagulation.
• a coagulant i.e. an emulsion, dispersion or solution of a substance with oppositely charged particles from said latex
• Latices existing on the market today are a stable dispersion of a polymeric substance in an essentially aqueous medium.
• a latex during its preparation is stabilized by special emulsifiers which can be either cationic, anionic or nonionic.
• Operable latexes herein are those having been stabilized with either cationic or anionic emulsifiers thereby rendering positively or negatively charged polymerized particles.
• One method of impinging two streams of oppositely charged particles is by spraying.
• the impingement from the spray jets can take place on the substrate or preferably immediately prior to the impinged streams hitting the substrate.
• Spraying can be accomplished by conventional means such as a double nozzle spray air gun or double nozzle spray paint guns employing electric motors and pumps.
• latices Most known commercially available latices today contain particles which carry negative charges. Such latices are descirbed as anionic. Examples of latices containing particles which carry negative charges operable herein include, but are not limited to, polyvinyl chloride, polyvinylidene chloride, polychloroprene, polyvinylacetate, polybutadiene, polyisoprene (natural rubber or synthetic natural rubber), butadiene/styrene copolymers, butadi- 3 polymers, butyl rubber (polyisobutylene or isobutylene/ styrene), polyvinylpyridine, polyethylene and oxidized polyethylene. Cationic latices are also known. The particles in such latices carry positive charges. Examples of cationic latices include, but are not limited to, polychloroprene, polyethylene and oxidized polyethylene.
• the coagulants used in the instant invention to coagu late the latex are well-known conventional materials.
• a coagulant such as a strong acid e.g. sulphuric, hydrochloric, phosphoric, etc., metallic ions, especially bivalent metallic ions e.g. calcium, magnesium, strontium, barium, zinc, etc., water-miscible organic solvents, e.g. ethyl alcohol, acetone etc., polymer-miscible organic solvents e.g. benzene, carbon tetrachloride, etc. and cationic surface-active substances e.g. neoprene latex 11-950 commercially available from E. I. du Pont.
• the coagulant can be a strong base e.g. sodium hydroxide or potassium hydroxide or other well known conventional coagulant.
• the latex particles during the drying operation form a solid film by slowly squeezing out the aqueous phase which evaporates.
• a debonding agent is necessary to prevent this film from adhering to the surface.
• aforesaid additives may be present in quantities up to 250 parts per 100 parts of polymer in the latex by weight and preferably 0.01-200 parts on the same basis.
• an air pressurized spray gun assembly having dual pressure feed tanks and spray guns with intersecting axes was used.
• the assembly was charged in tank A with a mixture of an anionic Neoprene latex L-572 (50% solids, solubility parameter 9.2) and 5% by wet weight of the various debonding agents shown in Table I and in tank B with a mixture of a cationic Neoprene latex L-950 (50% solids, solubility parameter 9.2) and 5% by wet weight of the various debonding agents shown in Table I.
• Both Neoprene latices are commercially available from E. I. du Pont.
• the latices were sprayed simultaneously at room temperature C.) onto 6" x 6" glass plates to form dried coatings having thicknesses as shown in Table I. After spraying, the coatings were dried for 48 hours and then measured for adhesive peel strength by the procedure of ASTMD- 1000 against a control without any debonding agent. The measurements were made using 1" x 6" samples on an Instron Tensile Tester at a rate of l inch/min. with 180 peel. The results in Table I show up to a 98% decrease in peel strength to remove the coating from the glass substrate.
• solubility parameters are alike, the materials tend to form a solution. The greater the ditference however, between the solubility parameters the 1 more immiscible the materials become. See Skeist Handbook of Adhesives Reinhold Publishing Corp., 1966, pages 10 and 11. Thus in the instant invention it is necessary that the debonding agent has a solubility parameter at least 2 (cal./cc.) higher than the latex polymer to decrease adhesion and allow stripping.
• the amount of the debonding agent added to the compositon can be varied between about 0.1 to 20% by"
• An air pressurized spray gun assembly having dual pressure feed tanks and spray guns with intersecting axes was used. The assembly was charged in tank A with a mixture of cationic Neoprene latex L-950, 50% solids, solubility parameter 9.2 (cal/cc)" commercially available from E. I. Dupont and Co. and 5% by wet weight of glycerin and in tank B with a mixture of an anionic latex of polyvinyl chloride, 56% solids, solubility parameter 9.6 (cal./cc.) Geon 151 commercially available from B. F. Goodrich Chemical Co.
• the mixtures were sprayed simultaneously at room temperature (25 'C.) onto a 6" x 6" piece of mahogany wood to form a dried coat having a thickness of about 2-3 mils.
• the coated Wood was cut in half and the coating was removed from one piece of the wood after one day of coagulation and from the other piece after 3 weeks. In both cases the coating was readily hand stripped from the wood substrate.
• Neoprene latex L-572 E. I. du Pont Co.;
• Butadiene/Acrylonitrile Copolymer 62% solids, solubility parameter 9.5 (-cal./cc.) Nitrex J-8343, Naugatuck Chemical Div. of US. Rubber Co.
• Carboxylated Butadiene/Styrene Copolymer 49% solids, solubility parameter 8.5 (cal./cc.) Tylac 1372, International Latex Corp.;
• Example 11 was repeated except that 150 parts bentonite clay was dispersed in the coagulant solution. The stripping results were substantially the same.
• EXAMPLE 13 An air pressurized spray gun assembly having dual pressure feed tanks and spray guns with intersecting axes was used. The assembly was charged in tank A with a mixture of an anionic Neoprene latex L-572 (50% solids, solubility parameter 9.2) commercially available from E. I. du Pont, and 5% by wet weight of glycerin, and in tank B with a mixture of a 5% aqueous solution of magnesium aluminum sulphate and 5% by wet weight of glycerin. The mixtures were sprayed simultaneously at room temperature (25 C.) onto a 6 x 6" piece of pine wood. Within 5-10 minutes a coagulated coating about 3 mils thick resulted. After drying for 48 hours under ambient conditions the coating was readily hand stripped from the wood substrate. A control using the same reactants and procedure except that the glycerin was omitted resulted in a coagulated coating which could not be hand stripped.
• an anionic Neoprene latex L-572 50% solids, so
• Example No. 2 was repeated except that the substrate for the coating was varied in each instance to a 6" x 6" piece of wood, painted wood, enameled wood, steel, aluminum, tin free steel, copper, concrete, woven and nonwoven fabrics both natural and synthetic, paper, paper board, porcelain, ceramic, brick, cinder block, plaster and certain plastics including but not limited to polycarbonate, poly(methylmethacrylate), nylon, poly(ethyleneterephthalate), poly(phenylene oxide) and fiber glass reinforced polyester. In all cases the coating containing the debonding agent was more readily stripped from the substrate as compared to a control.
• these coatings Whether or not they contain a debonding agent can be stripped by applying an external debonding agent at the interface between the coating and the coated substrate.
• These external debonding agents have the same characteristics as those set out supra for the internal debonding agent added to the composition prior to coating. The following examples show the use of an external debonding agent.
• EXAMPLE 15 An air pressurized spray gun assembly having dual pressure feed tanks and spray guns with intersecting axes was used. The assembly was charged in tank A with an anionic ,Neoprene latex L-572 (50% solids, solubility parameter 9.2) and in tank B with a cationic Neoprene latex IP950 (50% solids, solubility parameter 9.2), both latices being commercially available from E. -I. du Pont and Co. The latices were sprayed simultaneously at room temperature onto a 6" x 6" piece of mahogany. The coating was dried under ambient conditions for 48 hours. The edge of the interface (1" wide strip) between the coating and the mahogany was exposed by inserting a knife blade therebetween. A drop of water was placed in the interface. Using the same adhesive peel strength test set out in Table I the coating had a peel strength of 0 g./in.
• Example 15 was repeated except that a drop of glycerin was used instead of water. The results were the same.
• an air pressurized spray gun assembly having dual pressure feed tanks and spray guns with intersecting axes was used.
• the assembly was charged in tank A with a mixture of an anionic Neoprene latex L-572 (50% solids, solubility parameter 9.2) and varying amounts on a wet weight basis of glycerin and in tank B with a mixture of a cationic Neoprene latex L-950 (50% solids, solubility parameter 9.2) and varying amounts on a wet weight basis of glycerin.
• the amount of glycerin shown in Table II was divided equally between tank A and tank B.
• the latices were sprayed simultaneously at room temperature (25 C.) onto 6" x 6" glass plates to form coatings.
• a process for forming a strippable coating on a sub strate which comprises simultaneously impinging on said substrate two streams under ambient conditions, the first stream being a latex of a high polymer, said polymer particles in said latex being electrically charged and a second stream being a coagulant charged oppositely to that of the particles in said latex, at least one of said streams containing therein between about 0.1 to 20 percent by weight of the polymer in the latex of a debonding agent consisting essentially of a substantially non-volatile additive which is abhesive to at least one of either the substrate or coagulated coating, more soluble in water than in the coagulated latex polymer component and having a solubility parameter at least 2 (calories/cc.) higher than the coagulated latex polymer component.

Landscapes

• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Paper (AREA)
• Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
• Aftertreatments Of Artificial And Natural Stones (AREA)

Priority Applications (9)

Applications Claiming Priority (1)

Related Child Applications (1)

Publications (1)

Family

ID=22953789

Family Applications (1)

Country Status (8)

Cited By (7)

Families Citing this family (3)

• 1972
  • 1972-05-10 US US00251880A patent/US3823024A/en not_active Expired - Lifetime
• 1973
  • 1973-02-22 AU AU52474/73A patent/AU5247473A/en not_active Expired
  • 1973-03-29 JP JP48035168A patent/JPS4923189A/ja active Pending
  • 1973-05-03 BE BE130702A patent/BE799047A/xx unknown
  • 1973-05-07 BR BR3267/73A patent/BR7303267D0/pt unknown
  • 1973-05-08 FR FR7316574A patent/FR2184335A5/fr not_active Expired
  • 1973-05-08 IT IT23851/73A patent/IT987216B/it active
  • 1973-05-09 DE DE2323329A patent/DE2323329A1/de active Pending

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