Note: Descriptions are shown in the official language in which they were submitted.
WO91/16143 PCT/~S91/02~9
2 ~
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 Seri~l No. 945,~95 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.
BACK~ROUND OF THE INVENTION
l. Field of the Invention
This invention relates to U.V. stabilized polyvlnyl
chloride articles, and, more particularly, to color pigmen~ed
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 o~ any titanium dioxide therein.
2. DescriPtion of the Prior Art
Titanium dioxide, which is a white pigment, has a dual
~unction in polyvinyl chloride articles. The first function
of titanium dioxide is to stabilize polyvinyl chloride
against the adverse effects of U.Y. radia~ion by absorbing,
reflecting, dispersing or scattering in th~ 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.~. stabilization, about 12 phr, precludes
deep coloration of su~h articles. In fact, only colored
articles of pastel shades can be obtained; deep shades of
brown, blue and maroon, for example, are not readiiy
attainable. Accordingly, it would be advantageous to provide
U.V. stabilized polyvinyl chloride articles characterized by
the substanti.al absence of any titanium dioxide therein.
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Of course, the absence of titanium dioxide is
accompanied by the loss of its U.V. stabil1zation 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
preven~ 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. l0, 1~75, 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 stabili~er, 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 s~reaky, hazy, and has
runs or poc}cmar}cs thereon.
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Other attempts at effective surface modification of
polyvinyl chloride are described by Xatz, et al., in the
IProceedings of the A.C.S. Div. of Org. Coatings and
Plastics" 36, (1) p. 202-205 (197~)); Katz, et al., Soc.
Plast. Eng., Tech. Papers (1976) '-, 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; t~nd Belgium Patent No.
612,206. However, none of these ~isclosed 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 re~ion is defined as a dep~h extending up to
about 200 microns from the surface, and at least 70~ of this
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stabilizing amount is present within the first 100 microns of
the surface region.
Ye~ 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:
RIEF 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 unaffec~ed by
the modification and thereby appears ~he same as that of an
unmodified side of the sheet.
The color pigment is present to render the article
translucent or opaque, and al o 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/m~.
A~ least 70 ~ of this stabilizing amoun~ is present within
the first 100 microns of the surface region.
~ he 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
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immersed body contacted through the liquid with a solution of
a ultraviolet light stabilizer in a suitable organic solvent,
residual stabilizer and solvent a:re displaced from the
modified surface in situ, that is, without contacting the
outside atmosphere, i.e. a non-evaporative environment.
DETAILED DESCRIPTION 3F 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, e~c.,
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. l 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~ s~abilizer material, which is
an amount of lF!ast 0.3 g/m2 of the surface sheet, and
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preferably about 0.5 to lO.7 g/m2 thereof, 70~ or more of
the stabilizer is found within the first lO0 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 s~illed 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
~y U.V. dègradation accompanying outdoor weathering, and,
particularly, PVC residential; siding.
Accordingly, polyvinyl chloride i~ the preferred resin
for the article of the invention. However, other resins
susceptible to impregnation with U.V. stabilizers also are
suitable.
R ferring 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 ~he 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 ~nd 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.
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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 aqu~ous
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 pre~erred 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 arran~ement 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. stabili~er 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
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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 havi.ng a high degree of surface
perfection, and for ecological reasons.
The apparatus of FIG. 2 includes a tank l 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 poly~in~l chloride, for
example, is fed through the upper layer at a predetermined
rate rrom 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 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 stabili~er 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 e~posing 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 so].id stabilizer material thereon.
In the clisplacement zone, a jet element 9 directs a
spray of displacin~ liquid, preferably water 2, at a pressure
sufficient to displace residual stabilizer solution from the
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WO91~16143 PCT/-S91/02~49
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treated surface of the strip. Jet element 9 comprises a
hollow, perforated rod lO terminating the slit ll 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 ~he 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 l, 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. l.
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 ~alues. The
YI values were determined by accelerated U.V. exposure
tes~s, 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 evid~ences increasing yellowness caused by U.V.
exposure.
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E~AMPLE 1
PREPARPTION OF U.V. STABILIZED ARTICLE OF INVENTION
A solution of 10% by weight of Cyasorb 5411 U.V.
stabilizer (a trademark o~ 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 16C. (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. Visc. = 0.92 by
ASTM D 1243) containing 5.0 phr of an impact modifier, 1.O
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 ~one, 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.
~X~MPLE 2
STRUCTURE OF U.V. STABILIZED ARTICLE IF INVENTION
The U.V. stabilized article prepared in Example 1 has a
sur~ace 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.; 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 stabili~er and
solvent (less than 1~ of each) are substantially absent on
the modified surface of the sheet. The surface if the
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WO91/16143 PCT/~S~1/02~49
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resultant product is uniform, non-tacky, has no streaks of
solid material thereon, and subst:antially retains its
original planarity and hardness.
E~AMPLE 3
Following the procedure of Example l, test samples were
prepared and weathered with the following results all the
data is shown as lO week QW unless otherwise noted.
TABLE 1
ALL SAMPLES WEATHERED IN QW
~` SamDle Color g/m- E ( YI)*
l blue** l.5 13.2
2 blue 0 > 60.0
~~3~ green*** ~ l.5 15.0 . . - ~~ -~- ~~~
4 green 0 26.6 (6 weeks Q W )
~ 5 brown**** 3 5.4
: 6 brown 0 21.2
` 7 white (pearlescent)+ 3 l.7
8 white (pearlescent) 0 8.2
9 white ~pearlescent) 3 l.8
white (pearlescent) 0 21.4
ll brick red++ 3 5.6
;~ 12 brick red 0 23.9 (6 weeks Q W )
~
:~` SAMPLES WEATHERED OUTDOORS (NEW JERSEY)
SANPLE COLOR q/m2 E (21 months)
13 blue l.0 l9.9
l4 blue l.5 5l.5
*Changes in color level, after weathering, are expressed
as E, an energy value conventionally used in color technology
to describe color intensities.
Samples l, 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-9l86 Iron Free Chestnut Browm
+ EM-Chemicals, Rutile Fine Silver WR Pearlescent
Pigment 9111
++ Mobay, Corp., Quindo Red R-6713
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WO91/16143 PCT/~S91~02~9
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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 l~incompatible~
with the organic solvent. The te~n "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
di~thyl 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 me~hylene 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 V.V. 531: 2-hydroxy-4-n-otctoxybenzophenone
(Trademark of American Cyanamid)
Cyasorb U.V. 5411: 2(2'-hydroxy- 5'-t-octylphenyl)
benzotriazole tTrademark of American Cyanamid)
Tinuvin P: 2~2~hydroxy-5~-methylphenyl)benzotriazole
(Trademark of Ciba-Geigy)
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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 r -dihydroxybenzphenone. :
2,2,4,4'-tetrahydroxybenzophenone
2,2'-dihydroxv-4,4'-dimethoxybènzophenone
2,2'-dihydroxy-4,4' diethoxybenzophenone
~,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
2-hydroxy-4,4',5'-trimethoxybenzophenone
2-hydroxy-4-ethoxy-4'-methylbenzophenene
2-hydroxy-4-ethoxy-4'-ethylbenzophenone
2-hydroxy-4-ethoxy-4'-propylbenzophenone
2-hydroxy-4-ethoxy-4'-methoxybenzophenone
2-hydroxy-4,4'-diethoxybenzophenone
2-hydroxy-4-ethoxy-4'-propoxybenzophenone
2-hydroxy-4-ethoxy-4'-butoxybenzophenone
2-hydroxy-4-ethoxy-4'-chlorobenzophenone
2-hydroxy-4-ethoxy-4; -bromobenzophenone
2-(2'-hydroxy-5'-methylphenyl)benzotria2O1e
2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole
2-(2'-hydroxy-3'methyl-5~t'-butylphenyl)benzotriazole
2-(2'-hydroxy-5'-cyclohexylphenyl)benzotriazole
2-(2'-hydroxy-3',5'-dimethylphenyl)benzotriazole
2-(2'-hydroxy-5'-t-butylphenyl)-5-cholrobenzotriazole and
2-(2'-hydroxy-3'-di-t-butylphenyl)benzotriazole
2,2'-dihydroxy-4-methoxy-4'-butoxybenzophenone
SUBSTITUTE SHE~T
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WO91/161~3 PCT/~S91/02~
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2,2'dihydroxy-4-ethoxy-4'-propoxybenzophenone
2,3'-dihydroxy-4,4'-diemthoxybenzophenone
2,3'-dihydroxy-4-methoxy-4'-butoxybenzophenone
2,3'-dihydroxy-4,4,5'-trimethoxybe:nzophenone
2-hydroxy-4,4,5'-trim~thoxybenzophenone
2-hydroxy-4,4,6'-tributoxybenzophe:none
2-hydroxy-4-ethoxy-2,4'-dibutylbenzophenone
2-hydroxy-4-propoxy-4,6'-dichloroblenzophenone
2-hydroxy-4-propoxy-4',6'-dibromobenzophenone
2,4-dihydroxybenzophenone
2-hydroxy-4-methoxybenzophenone
2-hydroxy-4-ethoxybenzophenone
2-hydroxy-4-propoxybenzophenone
2-hydroxy-4-butoxybenzophenone
2-hydroxy-4-methoxy-4'methylbenzophenone
2-nydroxy-4-methoxy-4'-proplyben~ophenone
2-hydroxy-4-methoxy-4'butylbenzophenone
2-hydroxy-4-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'-dimethoxy-3-methylbenzophenone
2-hydroxy-4,4'-2'-ethylbanzophenone
2-hydroxy-acetophenone
~ he 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 aceta~es 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 in:Eusion of the requisite amount of stabilizer in~o
SUBSTITUTE SHEET
WO91/161~3 PCT/~S91/02~9
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;
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 a].so to resin article impregnated
with additives other than U.V. stabili~ers. 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 unders~ood
that the present disclosure has been made only by way of example
and that numerous changes can be made withotlt departing from the
spirit and the scope of this invention.
SU8STITUTE SHEET
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