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
  • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
  • B05D1/20—Processes for applying liquids or other fluent materials performed by dipping substances to be applied floating on a fluid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C3/00—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material
  • B05C3/18—Apparatus in which the work is brought into contact with a bulk quantity of liquid or other fluent material only one side of the work coming into contact with the liquid or other fluent material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
  • B05C9/02—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material to surfaces by single means not covered by groups B05C1/00 - B05C7/00, whether or not also using other means
• • 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
  • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
• • 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
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/02—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to macromolecular substances, e.g. rubber
• • 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
  • C08J7/04—Coating
  • C08J7/044—Forming conductive coatings; Forming coatings having anti-static properties
• • 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
  • C08J7/04—Coating
  • C08J7/06—Coating with compositions not containing macromolecular substances
  • C08J7/065—Low-molecular-weight organic substances, e.g. absorption of additives in the surface of the article

Definitions

• This invention relates to U.V. stabilized articles, and, more particularly, to a PVC resinous sheet having its surface modified with a U.V. stabilizer.
• Another surface method comprises laminating the surface of the polymer with a layer of a film-forming material containing the U.V. stabilizer.
• This lamination approach unfortunately, suffers from the problems of incompatibilities between polymer, U.V. stabilizer, and the filmforming material and its carrier components.
• the laminated layer and the surface of the polymer do not adhere well, and delamination upon shock or impact is a serious problem.
• the swelling method is described by Katz, et al. in an artide in the "Proceedings of the A.C.S. Div. of Org. Coatings and Plastics" 36, (1) p. 202-205 (1976), entitled “Ultraviolet Protection of Transparent PVC by Diffusion Coatings”.
• Katz uses a dip method to impregnate a transparent PVC sheet to a given depth with a non-migrating ultraviolet light absorber.
• the dip technique comprises swelling the polymer with a carrier solvent, infusing the stabilizer from a solution thereof with the carrier, and, thereafter heating the treated polymer in air at an elevated temperature to drive the stabilizer below the surface of the polymer and to remove residual solvent. Under these process conditions, however, only a small amount of stabilizer is absorbed into the surface region.
• the dip method produces a product in which both sides of the sheet are modified with ultraviolet absorber.
• Plastics and their Manufacture describes various methods of applying a solution or suspension of an ultraviolet light absorber to the surface of a plastic sheet.
• the methods disclosed by Jochanan include immersion, spraying, brushing, roller-printing and curtain-coating.
• a large amount of residual stabilizer and solvent is left on the surface of the article, whereupon the modified surface is observed to be streaky, hazy, and has runs or pock- marks thereon.
• Humphrey in U.S. 4,146,658, describes a process for producing an ultraviolet light stabilized polycarbonate article by dipping the polycarbonate sheet into an impregnating solution consisting of a selected combination of ultraviolet absorber and solvent.
• an impregnating solution consisting of a selected combination of ultraviolet absorber and solvent.
• Ching in U.S. 4,349,607, describes the incorporation of certain U.V. stabilizers into thermoplastic resins by dipping, spraying and brushing followed by heating at 70°C., which method is unsatisfactory for providing surface modified PVC sheets having a high degree of surface perfection.
• Amborski in U.S. 3,043,709, discloses an organic polymeric article having an ultraviolet light absorber compound incorporated adjacent to the surface of the article.
• the article is treated by several methods, including dipping-coating a polyethylene terephthalate film in a stabilizer solution, or applying a dispersion or melt of the absorber, or applying the absorber as a powder, and, thereafter, the coated film is heated in air to 115°C. and above to drive the absorber below the surface of the film and to remove the solvent.
• These processes are disadvantageous because they require heat-treatment to fully modify the surface of the film.
• these methods form an article in which considerable residual absorber is present on both sides of the film, which affects its surface perfection and appearance. Fanning, in U.S.
• 3,297,462 discloses a process for rendering polymeric films resistant to the deteriorating effects of sunlight by immersing them in a solution of a benzophenone stabilizer in a solvent mixture of diethylene glycol and glycerine, and then washing successively in diethylene glycol and water.
• the polymers suitable for such treatment must have a zero strength temperature of at least 200°C., which excludes many useful polymers, including polyvinyl chloride.
• Solvay and Cie in Belgium Patent No. 612,206, discloses a process for surface treating rigid polyvinyl chloride objects.
• the method comprises immersing the object in a swelling solvent containing a light stabilizer and then evaporizing the . solvent in air.
• This procedure is ineffective because some stabilizer remains on the treated surface of the object, which gives a poor physical appearance, and, environmental hazards are created during removal of the solvent in air.
• Baumgaertel, H. et al., FRG Patent Applications 28 08 005 and 28 08 036, both filed 2/24/78, laid-open 8/30/79 describes a process for regenerating installed, weathered PVC siding by spraying, brushing, or roller-coating the object with a solution of a U.V. absorber in an organic solvent or mixture of solvents.
• Baumgaertel's method of treatment merely coats stabilizer onto the regenerated surface. This process also changes the base thermoplastic material which has been degraded by sunlight.
• the treated PVC is modified with stabilizer within the surface region and is unaffected by such modification. Thereby, the article herein has long-term stability and retains its original appearance.
• a surface modified, U.V. stabilized PVC siding article preferably should have only one side surface modified with the stabilizer material.
• the exposed surface of the sheet should be substantially free of residual stabilizer and solvent material, and the appearance and degree of surface perfection of the modified side should be the same as that of the unmodified side of the sheet.
• the surface modification should be effected in situ to lesson environmental hazards.
• a surface modified, U.V. stabilized article which includes a resinous sheet whose sides are both exposed to the air.
• the surface region of one side of the sheet is substantially fully modified in situ with a stabilizing amount of an ultraviolet light stabilizer material, while the exposed surfaces are substantially free of residual stabilizer and solvent material, and the appearance and degree of surface perfection of the modified side are substantially the same as that of the unmodified side of the sheet.
• the surface region of the sheet extends for a depth of up to 200 microns from the surface.
• This region is fully modified in situ in this invention with a stabilizing amount of a ultraviolet light stabilizer comprising at least 0.3 g/m 2 of the surface of the sheet, preferably 0.5 g. to 6.0 g./m 2 . At least 70% of this stabilizing amount is present within the first 100 microns of the surface region, and 0.1 to 0.6 g/m 2 is present in the first 20 microns from the surface.
• the U.V. stabilized resin article is made by a continuous process comprising immersing a resin body in a suitable liquid media, and- contacting the surface of the immersed body through the liquid with a solution of a ultraviolet light stabilizer in a suitable organic solvent and displacing residual stabilizer and solvent from the modified surface in situ, both step being carried out without exposing the m ⁇ dified surface to the atmosphere.
• the method of this invention thus involves incorporating at least on ingredient in a polymer fabricated from a polymer by the steps of:
• non-aggressive is used herein to signify that the liquid will not dissolve, swell or otherwise react with the polymer and is to be considered inert towards the polymer.
• the method comprises incorporating at least one ultraviolet light stabilizer in the surface region of an article fabricated from PVC by the steps of:
• the process is practiced in a continuous mode and involves incorporating at least one ultraviolet light stabilizer in the surface region of a sheet fabricated from PVC.
• the surface region extends up to a depth of about 200 microns and the amount of stabilizer incorporated in this region will be at least 0.3, preferably 0.5 to 6.0 g/m 2 of the surface of the PVC sheet, with at least 70% of such amount concentrated in the upper 100 microns of the surface region.
• This most preferred embodiment involves:
• Fig. 1 shows the U.V. stabilized article of the present invention.
• Fig. 2 is a scanning election micrograph of the modified surface of a stabilized PVC article in accordance with the present invention.
• Fig. 3 shows the untreated surface of the sheet of Fig. 2.
• Fig. 4 shows the modified surface of Fig. 2 after weathering for 15 mos. in sunlight.
• Fig. 5 shows the untreated surface of Fig. 3 after weathering for 15 mos. in sunlight.
• Fig. 6 is a schematic representation of an apparatus for making the U.V. stabilized article of Fig. 1 by a continuous process.
• Fig. 1 shows the U.V. stabilized article of the present invention.
• the article includes a resin body, such as a sheet or other shaped structure thereof of polyvinyl chloride or another polymeric resin.
• the article has sides S and S', both of which are exposed to the air. Each exposed side has respective surfaces SUR and SUR'.
• Side S has a surface region SR extending from surface S to a depth of about 200 microns into said sheet.
• Surface region SR is modified with a stabilizing amount of a U.V. stabilizer material, which is an amount of least 0.3 g/m 2 , preferably 0.5 to 6.0 g/m 2 of the surface of the sheet, and most preferably about 1.8 g/m 2 thereof.
• 70% or more of the stabilizer is found within the first 100 microns of the surface region at least 0.1 preferably at least 0.3 to 0.6 g/m 2 is present in the first 20 microns.
• Stabilizer is substantially absent in the interior or bulk of the sheet, and surface SUR also is substantially free of residual stabilizer.
• the uniformity, appearance and degree of surface perfection of the modified surface SUR is substantially the same as that of the unmodified surface SUR'.
• Surface perfection is defined as a surface which is non-tacky and non-streaking, and which retains its original shape and hardness after being modified with stabilizer.
• FIGs. 2-5 there are shown scanning electron micrographs of the modified surface SUR of the U.V. stabilised resin sheet (Fig. 2), its corresponding unmodified surface SUR' (Fig. 3), the modified surface after weathering (Fig. 4), and the unmodified surface after weathering (Fig. 5).
• These micrographs illustrate that the surface of the treated resin article herein (Fig. 2) has substantially the same degree of surface perfection as that of its untreated surface (Fig 3).
• the treated surface (Fig. 4) remains substantially unaffected by exposure to ultraviolet light for a protracted period of time, while the untreated surface (Fig. 5), under similar conditions of exposure, has deteriorated perceptibly.
• the shaped resin body itself is obtained by general mechanical processing techniques known to those skilled in the art. II- lustrative of such mechanical operations are compression, injection, jet, transfer molding, vacuum forming, extrusion and the like. Such bodies can range from flexible sheets to rigid structural members. However, the invention is aimed particularly at articles which are plagued by U.V. degradation accompanying out- door weathering, and, particularly, PVC residential siding.
• polyvinyl chloride is the preferred resin for the article of the invention.
• resins susceptible to impregnation with U.V. stabilizers also are suitable, including ABS (acrylonitrile/butadiene/styrene) rubber, polypropylenes, polyacrylates, polymethacrylates and polyesters, e.g. polyethylene terephthlate and polybutylene terephthlate.
• the resin article itself may be transparent, translucent, opaque or pigmented.
• Fig. 6 there is shown schematically an apparatus useful for making the U.V. stabilized resin article of the invention.
• the method comprises immersing a resin sheet in a suitable liquid media, contacting the surface of the immersed sheet to be modified through the liquid with a solution of an ultraviolet light stabilizer in a suitable organic solvent, and displacing residual stabilizer and solvent from the treated surface in situ.
• Suitable solvents are those which swell the resin effectively and are immiscible with the organic solvent and non-aggressive towards the resin.
• the preferred in situ method of making the U.V. article of the invention is a continuous process which comprises immersing the resin sheet in an aqueous liquid, e.g. water, flowing a solution of an ultraviolet light stabilizer in a resin-swellable organic solvent through the water into contact with the surface of the sheet to be modified while it is immersed in the water, thereupon causing the surface contacted to swell sufficiently to allow the stabilizer solution to fully penetrate into the surface region of the sheet, and then displacing residual stabilizer and solvent from the modified surface in situ, preferably with said aqueous liquid.
• an aqueous liquid e.g. water
• a solution of an ultraviolet light stabilizer in a resin-swellable organic solvent through the water into contact with the surface of the sheet to be modified while it is immersed in the water, thereupon causing the surface contacted to swell sufficiently to allow the stabilizer solution to fully penetrate into the surface region of the sheet, and then displacing residual stabilizer and solvent from the modified surface in situ,
• liquids such as water or aqueous solutions thereof, and organic solvents having a density greater than water or such solutions.
• the preferred arrangement of liquid and solution is a two-layered system, where water is the upper layer, and the solution of stabilizer in the organic solvent is the lower layer.
• the organic solvent is selected among solvents which do not mix with the liquid media; otherwise, the solvent would not reach the resin sheet but would simply dissolve therein.
• Another consideration in choice of solvent is an empirical one, namely, the desire to impregnate the resin article with the U.V. stabilizer within a minimum contact time. This property depends on a number of factors, particularly the ability of the solvent to effectively swell the resin surface.
• the system shown in Fig. 6 is a two-layered system in which the liquid phase is the upper layer and the stabilizer solution is the lower layer, and the resin sheet is oriented in an immersed state in the upper layer.
• the stabilizer solution is pumped from the lower layer and applied over the sheet from beneath the aqueous upper layer. Excess stabilizer solution then falls off the sheet by gravity to return to the lower layer.
• the organic solvent in the stabilizer solution is blocked from evaporating into the atmosphere by the blanket of liquid above it, which is advantageous for producing modified surfaces having a high degree of surface perfection, and for ecological reasons.
• the apparatus of Fig. 6 includes tank 1 about 3/4 full with water 2 as the upper layer.
• a continuous resin strip 4 of extruded polyvinyl chloride, for example, is fed into the upper layer at a predetermined rate from below roller 5, which is positioned below surface 6 of the water.
• roller 5 in what is referred to herein as the "application zone” A, a series of applicator nozzles 7 areoriented below the surface level 6 of the water with their orifices directed towards the surface of strip 4.
• the applicator nozzles continuously direct a stream of stabilizer solution 3 over the upper surface 8 of the moving resin strip 4.
• the thus- applied stabilizer solution remains on the surface of the strip whereupon the surface region is modified effectively with stabilizer.
• the length of time the stabilizer solution remains on the surface of the sheet within the application zone is referred to herein as the "contact time" of the process, defined hereinafter.
• a "displacement zone" B Downstream of the applicator zone is a “displacement zone" B, in which residual stabilizer solution is removed in situ from the thus-treated surface of the strip.
• the term "in situ” means that the displacement step is carried out without exposing the treated surface to the ambient atmosphere; rather, the surface remains under water where the solvent cannot evaporate. Such evaporation would leave streaks of solid stabilizer material thereon which is highly undesirable.
• the duration of passage from the applicator zone to the displacement zone is defined herein as the "contact time" of the process.
• a jet element 9 directs a spray of displacing liquid, preferably water 2, at a pressure sufficient to displace residual stabilizer solution from the treated surface of the strip.
• Jet element 9 comprises a hollow, perforated rod 10 terminating in slit 11 through which strip 4 is conveyed into the displacement zone.
• a second roller 12 is located ahead of the displacement zone and below the level of the water to accept the thus-treated resin strip after it leaves the displacement zone.
• Variable speed nip roller pullers (not shown) are positioned outside the tank to move the strip at a predetermined speed through and out of the tank, where it can be stored on a suitable take-up roll.
• the equipment and procedure described above also is applicable to organic solvents having a density which is less than one, e.g. ethyl acetate, 2-pentanone, 3-pentanone and the like.
• the stabilizer solution would constitute the top layer and water the bottom layer. The stabilizer solution then would rise in the water to contact the resin sheet from the underside, thereafter passing upwardly.
• ingredients which may be incorporated into the articles fabricated from such polymers include ultraviolet light stabilizers (which are preferred), anti-oxidants, anti-static agents, pigments and the like.
• ultraviolet light stabilizers which are preferred
• anti-oxidants anti-static agents
• pigments and the like.
• the nature of such ingredients is not critical so long as they are compatible with the polymer and with the solvent of choice. Of course, the ingredients must be sufficiently soluble on the solvent of choice so as to cause the desired amount thereof to be incorporated in the polymer article.
• the applicator nozzles were directed vertically towards the upper surface of the sheet from a position beneath the water level. Thereupon stabilizer was absorbed into the surface region of the upper surface of the sheet and excess solution fell to the bottom of the tank. The contact time was 24 seconds. Downstream of the applicator zone, a jet of water was applied to the treated surface to displace residual stabilizer and solvent still remaining on the treated surface. The U.V. stabilized article then exited the tank and was wound onto a take-up roll.
• the U.V. stabilized article prepared in Example 1 was microtimed into 20 micron sections extending to a total depth of 200 microns from the surface.
• the amount of U.V. stabilizer present in each of these sections was determined by means of high pressure liquid chromatography (HPLC) analysis. The results are given in Table I below.
• the test results in Table I show that 3.39 g/m 2 of the stabilizer is deposited within the surface region of one side of the sheet, i.e. within a depth of 200 microns from the surface, and 71% of this amount, or 2.42 g/m 2 , is present within the first 100 microns of the surface region.
• Within the interior or bulk of the sheet i.e. from 200 to 1300 microns (the thickness of the sheet) substantially no stabilizer is present.
• residual stabilizer and solvent are not present on the modified surface of the sheet.
• the resultant product had a uniform treated surface which was non-tacky, had no streaks of solid material thereon, and retained to original planarity and hardness.
• Table II shows the amount of the stabilizer incorporated into the surface region of the resin sheet for such various stabilizer concentrations and contact times using methylene chloride as the solvent.
• the depth profiles of a series of PVC articles surface modified in controlled laboratory experiments simulating the process of the invention were obtained to determine the effect of the concentration of the stabilizer at different depths within the surface region, particularly within the first 20 microns, upon the changes in yellowness index.
• These experiments demonstrate that excellent weatherability is obtained when at least 0.1 g/m 2 , preferably 0.1 to 0.6 g/m 2 of stabilizer is present within the first 20 microns from the surface of the sheet; and at least a total of 0.3 g/m 2 , preferably 0.3 to 6 g/m 2 , of stabilizer is present within the surface region of the sheet.
• the preferred liquid media in the method used herein is water or an aqueous solution or emulsion thereof.
• Other liquids can be used as long as they are “incompatible” with the organic solvent.
• incompatible is defined herein to mean a liquid having a solubility of no more than about 15 percent by weight in the organic solvent and at ambient temperature and pressure. Such liquids include alkanols and other water miscible liquids.
• liquid-immiscible solvent which also is defined as a solubility in liquid at ambient temperature and pressure of no more than about 15 per cent by volume.
• organic solvents suitable for use herein inelude water-immiscible organic solvents, as for example, halogenated hydrocarbons having up to six, preferably three, carbon atoms in the chain; ketones, both aliphatic and cycloaliphatic; aliphatic esters and the like.
• Representative halogenated hydrocarbons include methylene chloride, chloroform, 1,2-dichloroethane, 2-chloro-2-methylpropane and like chlorinated hydrocarbons.
• Exemplary ketones are 2-pentanone, 3-pentanone, 2- hexanone, 2,4-pentanedione and the like.
• Suitable ethers include diethyl ether, dipropyl ether, dimethoxy ethane, furan, tetrahydropyran and the like. Mixtures of mutually miscible or- ganic solvents can also be used.
• the preferred organic solvents are methylene chloride, 1,2-dichloroethane, ethyl acetate, 2- pentanone and 3-pentanone, and mixtures of these solvents.
• Suitable U.V. stabilizers include the following commercially available materials:
• Cyasorb U.V. 531 2-hydroxy-4-n-octoxybenzophenone (Trademark of American Cyanamid)
• Tinuvin P 2 (2'hydroxy-S'-methylphenyl)benzotriazole (Trademark of Ciba-Geigy)
• Tinuvin 326 2-(3't-butyl-2'-hydroxy-5'-methylphenyl)-5- chlorobenzotriazole (Trademark of Ciba-Geigy)
• Sanduvor VSU 2-ethyl-2-ethoxyanilide (Trademark of Sandoz Corp.)
• Tinuvin 144 and 770 hindered amine light stabilizers (Trademark of Ciba Geigy for HALS)
• Irgastab 2002 a nickel phosphate (Trademark of Ciba-Geigy)
• the preferred temperature for making the U.V. stabilized article of the present invention is ambient temperature.
• process temperatures lower and higher than ambient temperature may be used, if desired.
• the water solubility of certain useful organic solvents, e.g. ethyl acetate decreases with increasing temperature.
• process temperatures higher than ambient temperature for such solvents.
• organic solvents which swell a particular resin only modestly at room temperature can be rendered quite effective for infusion of the requisite amount of stabilizer into the surface region of the resin by raising the treatment temperature.
• the preferred embodiment of the stabilizer article herein has only one side of the article modified with stabilizer, it is understood that both sides may be modified, if desired, by directing jets of stabilizer solution towards both surfaces of the resin sheet.
• the article herein may or may not include a white pigment such as a compound selected from an inorganic metallic oxide, sulfate or carbonate, for example, titanium dioxide, antimony trioxide, magnesium oxide, silicon dioxide, zinc oxide, barium sulfate and calcium carbonate.
• Titanium dioxide which is a white pigment, has a dual function in polyvinyl chloride articles.
• the first function of titanium dioxide is to stabilize polyvinyl chloride against the adverse effects of U.V. radiation by absorbing, reflecting, dispersing or scattering in the incident U.V. energy.
• the second function of titanium dioxide is to render the article opaque so that colored articles may be produced, if desired, by including colorants therein in an amount sufficient to overcome the white titanium dioxide present.
• titanium dioxide is such a cheap raw material, it is uneconomical to substitute an effective, but high priced organic U.V. stabilizer, such as a benzophenone or benzotriazole, in place of titanium dioxide.
• organic U.V. stabilizer such as a benzophenone or benzotriazole
• photodegradation is known to be surface phenomenon, bulk incorporation of such organic U.V. stabilizers is inefficient because the stabilizer is present substantially in the interior of the article, where it does not prevent surface photodegradation.
• titanium dioxide can be absent or, if present herein, is included in an amount of 0.5 phr, preferably upto 8 phr, and optimally, about 1 to 6 phr, with or without a colored pigment, in the surface modified article of the invention.
• the solution of the modifier ingredient in a solvent may be applied to a resin article which passes through the solution, with the displacing liquid being present either above the solution, or in side-by-side relationship. In the latter embodiment, the displacing liquid need not be necessary immiscible with the solution and its solvent.

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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)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Laminated Bodies (AREA)

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• 1987
  • 1987-12-23 EP EP19880900942 patent/EP0296224A4/de not_active Withdrawn
  • 1987-12-23 AU AU11575/88A patent/AU632990B2/en not_active Ceased
  • 1987-12-23 WO PCT/US1987/003478 patent/WO1988004581A1/en not_active Application Discontinuation

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