AU7685091A

AU7685091A - Surface modified, u.v. stabilized, polyvinyl chloride article

Info

Publication number: AU7685091A
Application number: AU76850/91A
Authority: AU
Inventors: Michael Burchill; Joseph Silberman
Original assignee: Atochem North America Inc
Current assignee: Arkema Inc
Priority date: 1990-04-16
Filing date: 1991-04-15
Publication date: 1991-11-11
Also published as: IL97877A0; KR920702639A; EP0478747A1; CA2060664A1; WO1991016143A1; JPH05500987A; BR9105721A

Description

DESCRIPTION SURFACE MODIFIED, U.V. STABILIZED, POLYVINYL CHLORIDE ARTICLE CROSS-REFERENCE TO RELATED PATENT APPLICATIONS This application is in a continuation-in-part of copending U.S. Patent Applications Serial No. 945,595 and 945,757, both filed December 23, 1986, by the same inventor, and assigned to the same assignee, as herein. The entire disclosures of these applications are incorporated by reference herein. BACKGROUND OF THE INVENTION

1. Field of the Invention

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.

2. Description of the Prior Art

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.

Unfortunately, the amount of titanium dioxide necessary for effective U.V. stabilization, about 12 phr, precludes deep coloration of such articles. In fact, only colored articles of pastel shades can be obtained; deep shades of brown, blue and maroon, for example, are not readily attainable. Accordingly, it would be advantageous to provide U.V. stabilized polyvinyl chloride articles characterized by the substantial absence of any titanium dioxide therein.

SUBSTITUTESHEET Of course, the absence of titanium dioxide is accompanied by the loss of its U.V. stabilization function. Therefore, for such articles, it is necessary to provide an alternative means of U.V. stabilization for such articles. Since 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. Furthermore, since photodegradation is known to be a 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 is does not act to prevent surface photodegradation. - -. - -

For these reasons, surface treatments of polyvinyl chloride articles containing titanium dioxide have been proposed to provide effective and economical U.V. stabilization for polyvinyl chloride resins. These prior art surface treatments are based on the ability of various organic solvents to swell the resin so that a solution of the U.V. stabilizer can be directed into the surface regions of the article, where protection is desired. However, none of these surface treatments have been very successful commercially.

For example, 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.

SUBSTITUTE SHEET Other attempts at effective surface modification of polyvinyl chloride are described by Katz, et al., in the "Proceedings of the A.C.S. Div. of Org. Coatings and

Plastics" 16., (1) p. 202-205 (1976); Katz, et al., Soc. Plast. Eng., Tech. Papers (1976) ~ 2~2~, 511-512; U.S. Patents

3,043,709; 3,297,462; 3,519,462; 3,783,011; 3,892,889;

4,146,658; 4,323,597; 4,349,067; and Belgium Patent No.

612,206. However, none of these disclosed processes have provided useful surface modified, U.V. stabilized, opaque polyvinyl chloride resin articles, for use, for example, in residential siding, which application requires particularly effective protection from the weathering effects of sunlight, an appearance and degree of surface perfection which is acceptable to the public.

Accordingly, 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/m² of the surface area of the sheet, and, most preferably, 0.5 to 10.7 g/m², 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.

These and other objects, features and advantages of the present invention will be readily apparent form the following detailed description thereof, which is read in connection with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

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.

SUMMARY OF THE INVENTION

What is described herein is a surface modified U.V. stabilized, color pigmented polyvinyl chloride resin article characterized by the substantial absence of titanium dioxide. The modified surface is substantially free of residual stabilizer and solvent used therewith, and its appearance and degree of surface perfection is substantially unaffected by the modification and thereby appears the same as that of an unmodified side of the sheet.

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/m² of the surface area of the sheet, and preferably about 0.5 to 10.7 g/m². 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

SUBSTITUTESHEET immersed body contacted through the liquid with a solution of a ultraviolet light stabilizer in a suitable organic solvent, residual stabilizer and solvent are displaced from the modified surface in situ, that is, without contacting the outside atmosphere, i.e. a non-evaporative environment. DETAILED DESCRIPTION OF THE INVENTION 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. For illustrative purposes only, the following description will be made by reference to a sheet article, which is intended to include such forms as a film, strip, ribbon, bar, rod, etc., but it will be understood that other shaped articles which are apparent to those skilled in the art also may be made herein.

The amount of color pigment suitable for incorporation with the polyvinyl chloride resin is an amount which will render the article translucent or opaque.

As will be demonstrated hereinafter, the surface modified article of the invention can provide effective U.V. stabilization in the substantial absence of titanium dioxide. In fact, unexpectedly, at a given level of modification with 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.

Referring now to the drawings, 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/m² of the surface sheet, and

SUBSTITUTE SHEET preferably about 0.5 to 10.7 g/m² 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.

Accordingly, polyvinyl chloride is the preferred resin for the article of the invention. However, other resins susceptible to impregnation with U.V. stabilizers also are suitable.

Referring now to FIG. 2, there is shown schematically an apparatus useful for making the U.V. stabilized resin article of the invention. In general, 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.

SUBSTITUTESHEET 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.

After contacting the surface of the sheet, excess . stabilizer solution falls or rises from the thus-treated surface. The particular direction will depend on the respective densities of the liquid and organic solvent employed. It is preferred to use liquids such as water or aqueous solutions thereof, and organic solvents having a density greater than water or such solutions. Accordingly, the preferred arrangement of liquid and solution is a two- layer 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 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. In operation of such a two-layer process in a continuous manner, the stabilizer

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.

Further ahead of roller 5, in what us referred to herein as the "application zone" A, 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.

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.

In the displacement zone, a jet element 9 directs a spray of displacing liquid, preferably water 2, at a pressure sufficient to displace residual stabilizer solution from the

SUBSTITUTE SHEET treated surface of the strip. 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. For such organic solvents, 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.

The invention will be described now with the reference to the following examples, in which the U.V. stabilizer article of the present invention is prepared using the apparatus and system of FIG. 1.

Protection of the article against deterioration by U.V. light under these process parameter is indicated in the graph as changes in yellowness index (YI), or 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.

SUBSTITUTE SHEET EXAMPLE 1

PREPARATION OF U.V. STABILIZED ARTICLE OF INVENTION A solution of 10% by weight of Cyasorb 5411 U.V. stabilizer (a trademark of American Cyanamid Co.) in methylene chloride was applied onto the upper surface if a horizontally supported, moving polyvinyl chloride resin strip containing 1-2 phr of color pigment. The strip was immersed in water at 16°C. (The PVC strips were milled and pressed samples made from a blend of vinyl chloride homopolymer (Geon 103EP F-76 from B.F. Goodrich Company; Int. Vise. = 0.92 by ASTM D 1243) containing 5.0 phr of an impact modifier, 1.0 phr of a processing aid, 2.0 phr of calcium stearate- lubricant, and 1.5 phr of tin mercaptide stabilizer).

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.

EXAMPLE 2 STRUCTURE OF U.V. STABILIZED ARTICLE IF INVENTION 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/m² of the surface area of the sheet, and, usually, about 0.5 to 10.7 g/m², and at least 70% of this amount of stabilizer 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. Furthermore, residual stabilizer and solvent (less than 1% of each) 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.

EXAMPLE 3 Following the procedure of Example 1, test samples were prepared and weathered with the following results all the data is shown as 10 week QUV unless otherwise noted.

TABLE 1

YI)

•(6 weeks QUV)

(6 weeks QUV)

SAMPLES WEATHERED OUTDOORS fNEW JERSEY) SAMPLE COLOR σ/mi E f21 months

13 blue 1.0 19.9

14 blue 1.5 51.5

*Changes in color level, after weathering, are expressed as E, an energy value conventionally used in color technology to describe color intensities.

Samples 1, 2, 13 and 14 were extruded strips of PVC.

Comparison of color pigmented samples with and without surface modified stabilizer material shows that weathering is very significantly improved with stabilizer present.

** Ferro F-8233

*** Ciba-Giegy, Irgalite green 44 LNP

**** Ferro V-9186 Iron Free Chestnut Brow

+ EM-Chemicals, Rutile Fine Silver WR Pearlescent

Pigment 9111 ++ Mobay, Corp., Quindo Red R-6713

SUBSTITUTE SHEET As described, the preferred liquid media in the method used herein is water or an aqueous solution or emulsion thereof. Other liquids, however, can be used as long as they are "incompatible" with the organic solvent. The term "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.

Similarly, 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.

Accordingly, 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. 9: 2-hydroxy-4-methoxybenzophenone (Trademark of American Cyanamid)

Cyasorb U.V. 531: 2-hydroxy-4-n-otctoxybenzophenone (Trademark of American Cyanamid)

Cyasorb U.V. 5411: 2(2'-hydroxy- 5'-t-octylphenyl)- benzotriazole (Trademark of American Cyanamid)

Tinuvin P: 2(2'hydroxy-5'-methylphenyl)benzotriazole (Trademark of Ciba-Geigy)

SUBSTITUTE SHEET Tinuvin 326: U-(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 following is a partial list of theses and other benzopheonoes and triazoles which are suitable U.V. stabilizers for use herein, although salieylates, formamidines, oxanilides, benzoates, etc. may be used as well. 2,2'-dihydroxybenzphenone 2,2,4,4'-tetrahydroxybenzophenone 2,2'-dihydroxy-4,4'-dimethoxybenzophenone 2,2'-dihydroxy-4,4'-diethoxybenzophenone 2,2'-dihydroxy-4 ,4'-dipropoxybenzophenone 2,2'-dihydroxy-4,4'-dibutoxybenzophenone 2,2'-dihydroxy-4-methoxy-4'-ethoxybenzophenone 2,2'-dihydroxy-4-methoxy-4'-propoxybenzophenone -hydroxy-4,4' ,5'-trimethoxybenzophenone -hydroxy-4-ethoxy-4'-methylbenzophenene -hydroxy-4-ethoxy-4'-ethylbenzophenone -hydroxy-4-ethoxy-4'-propylbenzophenone -hydroxy-4-ethoxy-4'-methoxybenzophenone -hydroxy-4,4'-diethoxybenzophenone -hydroxy-4-ethoxy-4'-propoxybenzophenone -hydroxy-4-ethoxy-4'-butoxybenzophenone -hydroxy-4-ethoxy-4'-chlorobenzophenone -hydroxy-4-ethoxy-4; -bromobenzophenone -(2'-hydroxy-5'-methylphenyl)benzotriazole -(2'-hydroxy-5'-t-butylphenyl)benzotriazole -(2'-hydroxy-3'methyl-5-t'-butylphenyl)benzotriazole -(2'-hydroxy-5'-cyclohexylphenyl)benzotriazole -(2'-hydroxy-3' ,5'-dimethylphenyl)benzotriazole -(2'-hydroxy-5'-t-butylphenyl)-5-cholrobenzotriazole and -(2'-hydroxy-3'-di-t-butylphenyl)benzotriazole ,2'-dihydroxy-4-methoxy-4'-butoxybenzophenone

TE SHEET ,2'dihydroxy-4-ethoxy-4'-propoxybenzophenone ,3'-dihydroxy-4,4'-diemthoxybenzophenone ,3'-dihydroxy-4-methoxy-4'-butoxybenzophenone ,3'-dihydroxy-4,4,5'-trimethoxybenzophenone -hydroxy-4,4,5'-trimethoxybenzophenone -hydroxy-4,4,6'-tributoxybenzophenone -hydroxy-4-ethoxy-2,4'-dibutylbenzophenone

2-hydroxy-4-propoxy-4,6'-dichlorobenzophenone

2-hydroxy-4-propoxy-4' ,6'-dibromobenzophenone

2,4-dihydroxybenzophenone -hydroxy-4-methoxybenzophenone

2-hydroxy-4-ethoxybenzophenone

2-hydroxy- -propoxybenzophenone

2-hydroxy-4-butoxybenzophenone

2-hydroxy-4-methoxy-4'methylbenzophenone

2-hydroxy-4-methoxy-4'-proplybenzophenone

2-hydroxy-4-methoxy-4'butylbenzophenone

2-hydroxy- -methoxy-4'-t-butylbenzophenone

2-hydroxy-4-methoxy-4'-chlorobenzophenone

2-hydroxy-4-methoxy-2'-chlorobenzophenone

2-hydroxy-4-methoxy-4'-bromobenzophenone

2-hydroxy-4,4'-dimethoxybenzophenone

2-hydroxy-4,4'-dimethoxy-3-methylbenzophenone

2-hydroxy-4,4'-2'-ethylbenzophenone

2-hydroxy-acetophenone

The preferred temperature for making the U.V. stabilized article of the present invention is ambient temperature. However, process temperatures lower and higher than ambient temperature may be used, if desirable. For example, the water solubility of certain useful organic solvent, e.g. ethyl acetates decreases with increasing temperature. Thus, it may be advantageous to use process temperatures higher than ambient temperature for such solvents. Similarly, 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

SUBSTITUTESHEET the surface region of the resin by raising the treatment temperature.

Although 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. For example, resins can be impregnated with such additives as anti-static agents, anti-oxidants, anti-block agents, dyes, slip additives, and the like.

Although the invention has been described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes can be made without departing from the spirit and the scope of this invention.

SUBSTITUTE SHEET

Claims

WHAT IS CLAIMED IS:

1. A U.V. stabilized article comprises: a resinous sheet which includes a colored pigment therein and a substantial absence of titanium dioxide whose sides are both exposed to the air, the surface region of one side of said sheet being modified with a stabilizing amount of an ultraviolet light stabilizer, the exposed surfaces being substantially free of stabilizer material, and the uniformity, appearance and degree of surface perfection of said modified side being substantially unaffected by said modification.

2. A U.V. stabilizer article according to claim 1 wherein said pigment renders the article translucent or opaque.

3. A U.V. stabilized article according to claim"1 which is pearlescent.

4. A U.V. stabilized article according to claim 1 wherein said stabilizing amount is at least 0.3 g/m² of^' the surface area of said sheet, said surface region extends to a depth of up to 200 microns from said surface, and at least 70% of said stabilizer material is present in the first 100 microns of said surface region.

5. A U.V. stabilized article according to claim 1 wherein said stabilizing amount is 0.5 to 10.7 g/m² of the surface area of said sheet.

6. A U.V. stabilized article according to claim 1 wherein said surface perfection is characterized by said surface being uniform, non-tacky, non-streaking and substantially retains its original shape and hardness.

7. A U.V. stabilized article according to claim 1 wherein said resin sheet is a flexible or semi-rigid polyvinyl chloride article.

8. A U.V. stabilized article according to claim 1 wherein said resin is a rigid polyvinyl chloride resin sheet.

9. A U.V. stabilized article according to claim 1 wherein said surface region is modified at ambient temperature.

10. A U.V. stabilized article according to claim 9 wherein said stabilizing amount is about 0.5 to 10.7 g/m² of the surface sheet.

SUBSTITUTESHEET

11. A U.V. stabilized article according to claim 1 wherein said stabilizer is a benzotriazole, benzophenone, benzoate, salicylate, formamidine, hindered amine, or oxanilide organic compound.

12. A process for producing the surface modified resin article which comprises applying a solution of U.V. stabilizer material in a solvent to a surface of a resin article which includes a colored pigment therein and a substantial absence of titanium dioxide, and displacing residual stabilizer and solvent from the thus-treated surface, both steps being carried out in an environment which is non-evaporative of said solvent.

13. A process according to claim 12 wherein both steps ar.e carried out without contacting the atmosphere.

14. A process according to claim 12 wherein said stabilizer is present within said surface in a stabilizing amount of at least 0.3 g/m² said surface.

15. A process according to claim 12 wherein said stabilizer amount is about 0.5 to 10.7 g/m².

16. A process according to claim 12 wherein said resin is polyvinyl chloride.

17. A process according to claim 12 wherein said process is carried out in a continuous manner on a moving resin sheet.

18. A process according to claim 12 wherein said solvent is a volatile organic solvent.

19. A process according to claim 12 wherein said solvent is methylene chloride.

20. A process according to claim 12 wherein said displacing step is carried out by directing a jet of water against the treated surface.

21. A method of incorporating at least one ingredient into a colored pigmented article having a substantial absence of titanium dioxide therein fabricated from a polymer which comprises immersing the article in a liquid and contacting the immersed article with a solution of the ingredient in a solvent, said liquid being one which is nonaggressive towards the article and immiscible with the solvent.

SUBSTITUTESHEET

22. The method of claim 21 wherein the polymer is polyvinyl chloride, and the article is rendered translucent or opaque by including said colored pigment therein.

23. The method of claim 21 wherein the liquid comprises an aqueous media.

24. The method of claim 23 wherein the aqueous media consists of water, or water and a water-miscible solvent.

25. The method of claim 21 wherein the solvent is methylene chloride.

26. A continuous method of incorporating at least one ultraviolet light stabilizer in the surface region of an opaque article fabricated from polyvinyl chloride and including. colore pigment but an absence of titanium dioxide therein, which comprises the steps of:

(a) transporting the article through an aqueous media;

(b) contacting substantially only one surface of the article with a solution of the stabilizer in an organic solvent while article is being transported through the aqueous media; said media being one which is non-aggressive towards the article and immiscible with the solvent; and

(c) displacing substantially any residual solution remaining on the contacted surface while avoiding escape of solvent into the atmosphere.

27. A continuous process for incorporating at least one ultraviolet light stabilizer in the surface region of a translucent or opaque sheet fabricated from polyvinyl chloride an including a colored pigment therein put substantially no titanium dioxide therein, said surface region extending to a depth of up t about 200 microns, the amount of stabilizer incorporated into the surface region being at least 0.3 g/m² of the surface of the article, with at least 70% of such amount concentrated in the upper 100 microns of the surface region, comprising the steps of:

(a) transporting the sheet substantially horizontally through an upper water layer, there being a methylene chloride solution containing 1 to 60 wt.

SUBSTITUTESHEET vol.% of the stabilizer present as a layer beneath the water later;

(b) flowing the solution from the bottom layer through the upper water layer onto substantially only one surface of the sheet as the sheet is being transported through the water layer such that the solution is in contact with surface for a period of time ranging from about 2 seconds to about 2 minutes; and thereafter

(c) directing a jet of water onto the contacted surface of the sheet while said sheet remains in said water layer, thereby to displace any residual solution on such surface.

SUBSTITUTE SHEET