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
  • 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
• • 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

Definitions

• This invention relates to U.V. stabilized polyvinyl . chloride articles, and, more particularly, to color pigmented polyvinyl chloride articles having a surface modified effectively with a U.V. stabilizer. Even more particularly, it is concerned with such articles which are characterized by the substantial absence of any titanium dioxide therein.
• 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.
• Jochanan in Israeli Patent No. 39037, published Nev. 10, 1975, entitled "U.V. - and Oxidation Proof Products from Organic Plastics and their Manufacture", describes various methods of applying a solution or suspension of a U.V. absorber onto the surface of the plastic sheet containing titanium dioxide.
• the methods disclosed by Jochanan include dipping the resin sheet into a solution of the stabilizer, or spraying, brushing, roller-printing or curtain-coating the solution onto the sheet. With such methods, however, a large amount of residual stabilizer and solvent is left on the surface of the article, and the modified surface is observed to be streaky, hazy, and has runs or pockmarks thereon.
• Plastics 16., (1) p. 202-205 (1976); Katz, et al., Soc. Plast. Eng., Tech. Papers (1976) ⁇ 2 ⁇ 2 ⁇ , 511-512; U.S. Patents
• an object of the present invention is to provide a surface modified, U.V. stabilized polyvinyl chloride resin article characterized by the substantial absence of titanium dioxide therein.
• a further object herein is to provide such articles which may be color pigmented to render the article translucent or opaque.
• Still another object herein is to provide such U.V. stabilized article in which the color pigment includes a pearlescent material.
• Another object of the invention is to provide such a resin sheet article wherein the modified surface is substantially free of residual stabilizer and solvent materials, and the appearance and degree of surface perfection of the modified side is unaffected by the modification and therefore is substantially the same as that of the unmodified side of the sheet.
• Another object herein is to provide such resin articles wherein the amount of stabilizer within the modified surface region of the sheet is at least 0.3 g/m 2 of the surface area of the sheet, and, most preferably, 0.5 to 10.7 g/m 2 , where the surface region is defined as a depth extending up to about 200 microns from the surface, and at least 70% of this
• SUBSTITUTE SHEET stabilizing amount is present within the first 100 microns of the surface region.
• Yet another object herein is to provide a method making such PVC articles in which the treated PVC sheet is protected from the atmosphere during formation of the surface modified article.
• FIG. 1 shows the U.V. stabilized article of the present invention.
• FIG. 2 is a schematic representation of an apparatus suitable for making the U.V. stabilized article of FIG. 1 by a continuous process.
• the color pigment is present to render the article translucent or opaque, and also may be white or pearlescent.
• the surface region of the sheet extends for a depth of up to 200 microns from the surface and is fully modified in situ with a stabilizing amount of ultraviolet light stabilizer, suitably with at least 0.3 g/m 2 of the surface area of the sheet, and preferably about 0.5 to 10.7 g/m 2 . At least 70 % of this stabilizing amount is present within the first 100 microns of the surface region.
• the U.V. stabilized resin article is made by a continuous process in which the polyvinyl chloride article is immersed in a suitable liquid media, the surface of the
• the article of the present invention is made by first blending a suitable amount of color pigment with polyvinyl chloride resin. The resultant mixture is processes into a shaped body, such as a sheet or other useful structure.
• the amount of color pigment suitable for incorporation with the polyvinyl chloride resin is an amount which will render the article translucent or opaque.
• the surface modified article of the invention can provide effective U.V. stabilization in the substantial absence of titanium dioxide.
• U.V. stabilizer in the surface region of the article, the effectiveness of such U.V. stabilization actually is enhanced in the absence of titanium dioxide in the article.
• 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 up to 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 of the surface sheet, and
• SUBSTITUTE SHEET preferably about 0.5 to 10.7 g/m 2 thereof, 70% or more of the stabilizer is found within the first 100 microns of the surface region.
• 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 unaffected by the surface modification process and is substantially the same as that of the unmodified surface SUR' .
• Surface perfection is defined as a surface which is non-tacky and nonstreaking, and which retains its original shape and hardness after being modified with stabilizer.
• the shaped resin body itself is obtained by general mechanical processing techniques known to those skilled in the art. Illustrative 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 outdoor weathering, and, particularly, PVC residential; siding.
• polyvinyl chloride is the preferred resin for the article of the invention.
• other resins susceptible to impregnation with U.V. stabilizers also are suitable.
• the method employed with such apparatus 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, are immiscible with the organic solvent and are 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, flying 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 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
• flying 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 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
• the organic solvent is selected among solvents which do not mix well 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 apparatus shown in FIG. 2 is a two-layer system in which the liquid phase is the upper layer and the stabilizer solution is the lower layer.
• the resin sheet is oriented in an immersed state in the upper layer.
• SUBSTITUTESHEET 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 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. 2 includes a tank 1 about 3/4 full with water 2 as the upper layer.
• Stabilizer solution 3 of U.V. absorber in an organic solvent, e.g. methylene chloride, is present as the lower layer therein.
• a continuous resin strip 4 of extruded polyvinyl chloride,- for example, is fed through the upper layer at a predetermined rate from below roller 5, which is roller positioned below surface 6 of the water.
• a series of applicator nozzles 7 are oriented below the surface level 6 of the water with their orifices directed towards one surf ce 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.
• 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 also carried out without exposing the treated surface to the ambient atmosphere; rather the treated surface remains under water where the solvent cannot evaporate. Such evaporation of solvent is particularly undesirable because it would leave streaks of solid stabilizer material thereon.
• a jet element 9 directs a spray of displacing liquid, preferably water 2, at a pressure sufficient to displace residual stabilizer solution from the
• Jet element 9 comprises a hollow, perforated rod 10 terminating the slit 11 through which strip 4 is conveyed into the displacement zone.
• the length of time the stabilizer solution remains on the surface if the sheet during passage from the application zone to the displacement zone is referred to herein as the "contact time" of the process.
• 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 fullers (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 in a suitable take-up roll.
• the equipment and procedure described above also is applicable to organic solvents having a density which is less than 1, 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.
• YI yellowness index
• delta YI values The YI values were determined by accelerated U.V. exposure tests, according to ASTM G 53-84. The change from initial to final YI is designated YI.
• a YI value of zero (or minus) indicates minimal or complete absence of yellowing; positive YI values evidences increasing yellowness caused by U.V. exposure.
• 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 rank. 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 was excited from the tank and wound onto a take-up roll.
• the U.V. stabilized article prepared in Example 1 has a surface region extending to a total depth of up to about 200 microns from the surface within the surface region.
• the amount of U.V. stabilizer present is at least 0.3 g/m 2 of the surface area of the sheet, and, usually, about 0.5 to 10.7 g/m 2 , and at least 70% of this amount of stabilizer is present within the first 100 microns of the surface region.
• substantially no stabilizer is present within the interior or bulk of the sheet. i.e. from 200 to 1300 microns (the thickness of the sheet).
• residual stabilizer and solvent are substantially absent on the modified surface of the sheet. The surface if the
• SUBSTITUTESHEET resultant product is uniform, non-tacky, has no streaks of solid material thereon, and substantially retains its original planarity and hardness.
• E an energy value conventionally used in color technology to describe color intensities.
• Samples 1, 2, 13 and 14 were extruded strips of PVC.
• 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 liquid includes alkanols and other water miscible liquids.
• the solvent in the stabilizer solution should be “liquid-immiscible solvent", which also is defined as a solubility in liquid at ambient temperature and pressure of no more than about 15 percent by volume.
• organic solvents suitable for use in herein include 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, 2chloro-2-methylpropane and like chlorinated hydrocarbons.
• Exemplary ketones are 2-pentanone, 3-pentanone, 2- hexanone, 2,4-pentanedione and the like.
• Suitable ethers include die hy1 ether, diprolyl ether, dimethoxy ethane, furan, tetrahydropyran and the like. Mixtures of mutually miscible organic 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-otctoxybenzophenone (Trademark of American Cyanamid)
• Tinuvin P 2(2'hydroxy-5'-methylphenyl)benzotriazole (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 desirable.
• the water solubility of certain useful organic solvent, e.g. ethyl acetates 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 preferred ambodiment of the stabilizer article herein has only one side of the article is 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 invention is applicable also to resin article impregnated with additives other than U.V. stabilizers.
• additives other than U.V. stabilizers.
• resins can be impregnated with such additives as anti-static agents, anti-oxidants, anti-block agents, dyes, slip additives, and the like.

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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)
• Laminated Bodies (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (8)

Cited By (9)

Citations (1)

• 1991
  • 1991-04-15 WO PCT/US1991/002449 patent/WO1991016143A1/en not_active Application Discontinuation
  • 1991-04-15 CA CA002060664A patent/CA2060664A1/en not_active Abandoned
  • 1991-04-15 JP JP3507772A patent/JPH05500987A/ja active Pending
  • 1991-04-15 AU AU76850/91A patent/AU7685091A/en not_active Abandoned
  • 1991-04-15 EP EP91907906A patent/EP0478747A1/en not_active Withdrawn
  • 1991-04-15 KR KR1019910701879A patent/KR920702639A/ko not_active Application Discontinuation
  • 1991-04-15 BR BR919105721A patent/BR9105721A/pt not_active Application Discontinuation
  • 1991-04-16 IL IL97877A patent/IL97877A0/xx unknown

Patent Citations (1)

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