CA1135919A - Oriented polyester articles having improved ultraviolet stability - Google Patents
Oriented polyester articles having improved ultraviolet stabilityInfo
- Publication number
- CA1135919A CA1135919A CA000331084A CA331084A CA1135919A CA 1135919 A CA1135919 A CA 1135919A CA 000331084 A CA000331084 A CA 000331084A CA 331084 A CA331084 A CA 331084A CA 1135919 A CA1135919 A CA 1135919A
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- Prior art keywords
- polyester
- ultraviolet light
- ultraviolet
- process according
- stabilizer
- Prior art date
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- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Artificial Filaments (AREA)
Abstract
Abstract of the Disclosure This invention relates to oriented polyester shaped, molded, or formed objects having improved ultraviolet stability and to a process for producing the same. More particularly, the invention relates to an oriented linear polyester film, fiber, foils, sheets, end other shaped, molded, or formed objects prepared from polyester compositions containing conventional monochromophoric ultraviolet stabilizers which when oriented provide objects having improved weatherability, Conventional monochromophoric ultraviolet stabilizers are those which contain a single ultra-violet absorbing chromophore.
Description
ORIENTED POLYESTER ARTICLES HAVING IMPROVED
_ ULTRAVIOLET SrrABILITY ___ This invention relates to oriented polyester films, fibers, foils, sheets and other shapedl molded or formed ob~ects having improved ultraviolet stability and to a process for pro-ducing the same. More particularly, the invention relates to an oriented linear polyester film, fiber, foils, sheets and other shaped~ molded or formed objects prepared from polyester composi~
tions containing conventional ultraviolet stabilizers which when oriented proyides ob;ects having improved weatherability and processes for ~heir preparation The degradative effects of ultraviolet light on various organic compositions are well known in the art. The photodeterio-ration or degradation is of particular concern with organic photo-degradable csmpositions which are exposed to ultraviolet light, such as sunlight, for long periods of time. One group of such ~-~
photodegradable o~anic compositions is polyesters such as homo-and copolyesters. On exposure to sunlight for extended periods of time, polyeste~ compositions degrade and their physical properties are reduced to render the polymeric composition less useful for most applications. Therefore, con:iderable effort hss been directed to providing a solution to the photodegradation problem of polymeric compositions. As a result of this effort~ there have been discovered many additives and stabilizer~ which greatly improye the outdoor ~eatherability of other various polymeric compositions, such as~ for example, polypropylene and the like.
Moreover, while various additives and stabilizers exhibit the pDwer to absorb electromagnetic radiation within the band of 2900 to 4000 A~ and, when incorporated in yarious plastic materials ... , .. ~ .. , such as transparent sheets, the resultant ~heet acts a~ a filter for all the radiation passing through and ~ill transmit only such radiations as are not absorbed by the sheet and/or the absorbing agent. It is thus possible to screen out undesirable radiations 5 and utilize the resulting transparent sheet as a filter in many , technical and commercial applications, such as wrappin~s for food products and the iike.
While there are many adclitives, stabilizers and mixtures thereof which are knowll in the art to improve the ultraviolet light stability of various organic compositions, there is a nPed in the art for more efficient and effective stabilizers to prevent the photodegradation of polyester compositions susceptible to photodegradation over extended periods of time. Therefore, to provlde a more effective and efficient ultraviolet stability for such ~olyester compositions susceptible to such degradation would be an advance in the state of the art.
It is~ there~ore, an object of the present invention to proyide more effec~ive and efficient ultraviolet light stabili~ier polyester compositions, Another ob~ect of the present invention is to provide polyester objects characterized by improved resistance to ultra-violet degradation;and deterioration~
It is still another object of the present invention to proyide linear polyester films which have improyed resistance to ultraviolet degradation.
It is a still furthe~ object of this invention to pro-yide processes ~or providing oriented po}yester objects having resistance to deterioration ~nd degradation by actinic radiation and especially ultraviolet radiation.
It is a still further objPct of this invention to pro-yide compositions and processes ~hich can proyide methods for improving ~he resistance of polyester materials to deterioration and degradation by actinic radiations, including short wave-length visible radiations.
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F~lrther ob~ects and advantages of the invention will be apparent to those skilled in the art from the accompanying dic-closure and claims.
In accordance with the present invention, oriented polyester ob~ects are provided which are prepared from amorphous linear polyester compositions which contain conventional ultra-violet stabilizers or ultraviolet screening agent5. Those ~oly-ester compositions are ~haped, molded or formed into ob~ects and oriented. The terms oriented or orienting, as u~ed throughout this specification, means stretching the obJect, such as film, foil, fiber, sheet or the like at a temperature below its softening temperature but above the second order transition temperature to proyide molecular orientation in the film in one or more directions.
For example, linear, amorphous polyesters such as polycethylene terephthalate~ ~PET~ do not respond well to photo-stabilization when conventional ultraviolet stabilizers are used.
Such con~entional stabilizers known to the art are, for example, hydro~ybenzophenones, ~hich can be dispersed in the molten poly-ester followed by extrusion. Also, it has been disclosed in the ~jrt that polyCethylene t~rephthalate2 can be stabilized against photode~radation by dyeing stabilizers into oriented films using polyhydric alcohols and then treating the dyed films under pre-scribed conditions. It is believed that the light absorber, when applied to polyester material with a carrier in accordance with 25 the disclosure in U~S. Patent 3~943~1O5J alters the structure of the polyester material so ~s to form a weatherable~ light resistant polyester. Our process is ~pplicable to any polyester6 that are capable of being formed into oriented sheets and fibers. 0ur process involves extruding a polyester sheet containing 0.01-10%
f ~ conventional ultraviolet light stabilizer, orienting (either uniaxially o~ biaxially~ the sheet or film and heat setting the oriented prod~ct under Festraint. This orientation, uniaxially or bia~ially) of the Above ilms at temperatures between 185F. and 215~, greatly incre~ses the ~eatherability of the films.
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~, Conventionally, 1 to 15-mil sheets of polyester are $ormed but we believe the invention is also ~pplicable for thicker sheets (e.g., I
150 mil) as well. I
One advantage of our process over the dyeing process i8 that we can use additives that ~re difficult to dye into the film because of insufficlent solubility in the dyebath and/or because of the slow rates of diffusion of the stabilizer into the polymer.
Also, we can use high molecular weight nonvolatile and nonextract-able additives in our process and thereby get an i~provement over existing products. Furthermore, it is less costly to extrude the stabilizer into the film than to use a costly dyeing, ~ashing, and drying process.
Polyesters useful in the present invention are prepared by reaction conditions well known in the art. These polyesters ~ay be homopolyesters or copolyesters prepared by reacting a dibasic acid (or ester? or mixtures thereof wlth aliphatic glycols or glycol mixtures. Such dibasic acids are, for example: tere-phthalic acid, adipic acid, sebacic acid, p,p-sulfonyldibenzoic acid, 1,2- or 1,3- or 1,4-~yclohexanedicarboxylic acid, 1,4 or 20 1~5- o~ 2,7- or 2~6-naphthalenedicarbo~ylic acid, 4,4'-diphenic acid, 4,4'-benzophenonedicarboxylic acid, etc. Such glycols are, for e~a~ple~ polymethylene glycols containing 2 ~o 10 carbon atoms such as ethylene glycol, 1,2- or 1,3-propanediol, 1,2- or 1,3- or 1?4~cyclohexanedimethanol, neopentyl glycol, 1,5- or 2,4-pentanediol, 25 1,6- or 2~5-hexanediol 7 1~3- or 2 ? 3- or 1,4-but~nediol, 2~2,4,4-tetramethylcyclobutane-1,3-diol, etc. Also modify ng amounts of p-hydroxyben~oic acid or ether glycols such as, for example, diethylene glycol, poly(ethyl glycol2, poly(propylene glycol2 and poly(butylene glycol~ may be added. Such polyesters may be amorphous pr crys~talline~ they must be able to be formed into films, sheets o~ molded obJects and have an ASTM (D648-56) 264 psi heat deflec-tion temper~tur~ of ?60C. Such polyester moldable compositions are, for example, poly(ethyl~ne terephthalate), polyCtetra~ethylene -~
terephthalate2 and the like~ Such polyesters useful in this ~3~ 3 inventlon have an inherent viscoslty of at least 0.4, preferably at least 0.4 to about 1.6 when measured at 25C. using 0.50 grams of polymer per 100 ml. of a solvent composed of 60 volumes of phenol and 40 volumes of tetrachloroethane.
The conventional ultra~iolet stabilizers or screening agents are generally used in an amount of from 0.01 to 10~, by weight, based on the weight of the organic material to which they are added. While a detectable aLount of ultraviolet screening ~nd stabilization may be obtained with amounts less than 0.01%, this amount of stabilization or screening ~ould be of little practical utility in a commercial application. Moreover, while amounts greater than 10%, by ~eight? provide effective ultraviolet stabllity and screening, such concentrations are undesirable because of cost and the deleterious effect which such concentrations may have on the mechanical properties of the organic composition in which the stabilizer is incorporated. Preferably, the stabilizer ls used in an amount of from about Q.l to about 3~, by weight. For example, an amount of 0~5%, by ~eight, of the stabilizer effectively stabiliz~s poly~tetramethylene terephthala~e) plastic compositions.
Conyentional monochromophoric ultraviolet stabilizers or absorbers useful in the present inventlon are, for example, 2-hydroxybenzophenone type stab$1izers~ compounds such ~s phenyl benzoates which form 2-hydroxybenzophenones on exposure to ultra-yiolet light, substit~ed ethyle~e type aromatic stabilizers, 2-hydro~yphenylbenzotriazole compounds, poly~eric photostabillzers and the like ultraviolet stabiliz~rs, Cne such group of 2-hydroxy-benzophenone compounds has the formula -R2 ~H
~ R3 wherein ~=~ 9=Y
Rl and R2 are -H, -~H? or ~n alkoxy group having 1 to 18 carbon atoms, with the proviso that R3 LUSt be either -OH or ~lkoxy. Examples of ~uch alkoxy groups having 1 to 18 carbon atoms are ~ethyloxy? ethyloxy? n-butyloxy, ;~ "
~3"~
_ ULTRAVIOLET SrrABILITY ___ This invention relates to oriented polyester films, fibers, foils, sheets and other shapedl molded or formed ob~ects having improved ultraviolet stability and to a process for pro-ducing the same. More particularly, the invention relates to an oriented linear polyester film, fiber, foils, sheets and other shaped~ molded or formed objects prepared from polyester composi~
tions containing conventional ultraviolet stabilizers which when oriented proyides ob;ects having improved weatherability and processes for ~heir preparation The degradative effects of ultraviolet light on various organic compositions are well known in the art. The photodeterio-ration or degradation is of particular concern with organic photo-degradable csmpositions which are exposed to ultraviolet light, such as sunlight, for long periods of time. One group of such ~-~
photodegradable o~anic compositions is polyesters such as homo-and copolyesters. On exposure to sunlight for extended periods of time, polyeste~ compositions degrade and their physical properties are reduced to render the polymeric composition less useful for most applications. Therefore, con:iderable effort hss been directed to providing a solution to the photodegradation problem of polymeric compositions. As a result of this effort~ there have been discovered many additives and stabilizer~ which greatly improye the outdoor ~eatherability of other various polymeric compositions, such as~ for example, polypropylene and the like.
Moreover, while various additives and stabilizers exhibit the pDwer to absorb electromagnetic radiation within the band of 2900 to 4000 A~ and, when incorporated in yarious plastic materials ... , .. ~ .. , such as transparent sheets, the resultant ~heet acts a~ a filter for all the radiation passing through and ~ill transmit only such radiations as are not absorbed by the sheet and/or the absorbing agent. It is thus possible to screen out undesirable radiations 5 and utilize the resulting transparent sheet as a filter in many , technical and commercial applications, such as wrappin~s for food products and the iike.
While there are many adclitives, stabilizers and mixtures thereof which are knowll in the art to improve the ultraviolet light stability of various organic compositions, there is a nPed in the art for more efficient and effective stabilizers to prevent the photodegradation of polyester compositions susceptible to photodegradation over extended periods of time. Therefore, to provlde a more effective and efficient ultraviolet stability for such ~olyester compositions susceptible to such degradation would be an advance in the state of the art.
It is~ there~ore, an object of the present invention to proyide more effec~ive and efficient ultraviolet light stabili~ier polyester compositions, Another ob~ect of the present invention is to provide polyester objects characterized by improved resistance to ultra-violet degradation;and deterioration~
It is still another object of the present invention to proyide linear polyester films which have improyed resistance to ultraviolet degradation.
It is a still furthe~ object of this invention to pro-yide processes ~or providing oriented po}yester objects having resistance to deterioration ~nd degradation by actinic radiation and especially ultraviolet radiation.
It is a still further objPct of this invention to pro-yide compositions and processes ~hich can proyide methods for improving ~he resistance of polyester materials to deterioration and degradation by actinic radiations, including short wave-length visible radiations.
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F~lrther ob~ects and advantages of the invention will be apparent to those skilled in the art from the accompanying dic-closure and claims.
In accordance with the present invention, oriented polyester ob~ects are provided which are prepared from amorphous linear polyester compositions which contain conventional ultra-violet stabilizers or ultraviolet screening agent5. Those ~oly-ester compositions are ~haped, molded or formed into ob~ects and oriented. The terms oriented or orienting, as u~ed throughout this specification, means stretching the obJect, such as film, foil, fiber, sheet or the like at a temperature below its softening temperature but above the second order transition temperature to proyide molecular orientation in the film in one or more directions.
For example, linear, amorphous polyesters such as polycethylene terephthalate~ ~PET~ do not respond well to photo-stabilization when conventional ultraviolet stabilizers are used.
Such con~entional stabilizers known to the art are, for example, hydro~ybenzophenones, ~hich can be dispersed in the molten poly-ester followed by extrusion. Also, it has been disclosed in the ~jrt that polyCethylene t~rephthalate2 can be stabilized against photode~radation by dyeing stabilizers into oriented films using polyhydric alcohols and then treating the dyed films under pre-scribed conditions. It is believed that the light absorber, when applied to polyester material with a carrier in accordance with 25 the disclosure in U~S. Patent 3~943~1O5J alters the structure of the polyester material so ~s to form a weatherable~ light resistant polyester. Our process is ~pplicable to any polyester6 that are capable of being formed into oriented sheets and fibers. 0ur process involves extruding a polyester sheet containing 0.01-10%
f ~ conventional ultraviolet light stabilizer, orienting (either uniaxially o~ biaxially~ the sheet or film and heat setting the oriented prod~ct under Festraint. This orientation, uniaxially or bia~ially) of the Above ilms at temperatures between 185F. and 215~, greatly incre~ses the ~eatherability of the films.
.: ,.
. : , : .: . , ~ , ' . : -~L3~
~, Conventionally, 1 to 15-mil sheets of polyester are $ormed but we believe the invention is also ~pplicable for thicker sheets (e.g., I
150 mil) as well. I
One advantage of our process over the dyeing process i8 that we can use additives that ~re difficult to dye into the film because of insufficlent solubility in the dyebath and/or because of the slow rates of diffusion of the stabilizer into the polymer.
Also, we can use high molecular weight nonvolatile and nonextract-able additives in our process and thereby get an i~provement over existing products. Furthermore, it is less costly to extrude the stabilizer into the film than to use a costly dyeing, ~ashing, and drying process.
Polyesters useful in the present invention are prepared by reaction conditions well known in the art. These polyesters ~ay be homopolyesters or copolyesters prepared by reacting a dibasic acid (or ester? or mixtures thereof wlth aliphatic glycols or glycol mixtures. Such dibasic acids are, for example: tere-phthalic acid, adipic acid, sebacic acid, p,p-sulfonyldibenzoic acid, 1,2- or 1,3- or 1,4-~yclohexanedicarboxylic acid, 1,4 or 20 1~5- o~ 2,7- or 2~6-naphthalenedicarbo~ylic acid, 4,4'-diphenic acid, 4,4'-benzophenonedicarboxylic acid, etc. Such glycols are, for e~a~ple~ polymethylene glycols containing 2 ~o 10 carbon atoms such as ethylene glycol, 1,2- or 1,3-propanediol, 1,2- or 1,3- or 1?4~cyclohexanedimethanol, neopentyl glycol, 1,5- or 2,4-pentanediol, 25 1,6- or 2~5-hexanediol 7 1~3- or 2 ? 3- or 1,4-but~nediol, 2~2,4,4-tetramethylcyclobutane-1,3-diol, etc. Also modify ng amounts of p-hydroxyben~oic acid or ether glycols such as, for example, diethylene glycol, poly(ethyl glycol2, poly(propylene glycol2 and poly(butylene glycol~ may be added. Such polyesters may be amorphous pr crys~talline~ they must be able to be formed into films, sheets o~ molded obJects and have an ASTM (D648-56) 264 psi heat deflec-tion temper~tur~ of ?60C. Such polyester moldable compositions are, for example, poly(ethyl~ne terephthalate), polyCtetra~ethylene -~
terephthalate2 and the like~ Such polyesters useful in this ~3~ 3 inventlon have an inherent viscoslty of at least 0.4, preferably at least 0.4 to about 1.6 when measured at 25C. using 0.50 grams of polymer per 100 ml. of a solvent composed of 60 volumes of phenol and 40 volumes of tetrachloroethane.
The conventional ultra~iolet stabilizers or screening agents are generally used in an amount of from 0.01 to 10~, by weight, based on the weight of the organic material to which they are added. While a detectable aLount of ultraviolet screening ~nd stabilization may be obtained with amounts less than 0.01%, this amount of stabilization or screening ~ould be of little practical utility in a commercial application. Moreover, while amounts greater than 10%, by ~eight? provide effective ultraviolet stabllity and screening, such concentrations are undesirable because of cost and the deleterious effect which such concentrations may have on the mechanical properties of the organic composition in which the stabilizer is incorporated. Preferably, the stabilizer ls used in an amount of from about Q.l to about 3~, by weight. For example, an amount of 0~5%, by ~eight, of the stabilizer effectively stabiliz~s poly~tetramethylene terephthala~e) plastic compositions.
Conyentional monochromophoric ultraviolet stabilizers or absorbers useful in the present inventlon are, for example, 2-hydroxybenzophenone type stab$1izers~ compounds such ~s phenyl benzoates which form 2-hydroxybenzophenones on exposure to ultra-yiolet light, substit~ed ethyle~e type aromatic stabilizers, 2-hydro~yphenylbenzotriazole compounds, poly~eric photostabillzers and the like ultraviolet stabiliz~rs, Cne such group of 2-hydroxy-benzophenone compounds has the formula -R2 ~H
~ R3 wherein ~=~ 9=Y
Rl and R2 are -H, -~H? or ~n alkoxy group having 1 to 18 carbon atoms, with the proviso that R3 LUSt be either -OH or ~lkoxy. Examples of ~uch alkoxy groups having 1 to 18 carbon atoms are ~ethyloxy? ethyloxy? n-butyloxy, ;~ "
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2,2-dimethylhexyloxy, n-pentyloxy, 2-ethylhexyl-oxy, heptyloxy, n-octyloxy, 2,2-dimethyldecylvxy, dodecyloxy, and the like. ~hese compounds and their preparation are well known in the art and are described in U. S. Patent 2,861,053.
One preferred species of such 2-hydroxy-benzophenones corresponds to the structure ~H
lo 3 ~ , 12 25 and can be called 4-(dodecyloxy)-2-hydroxy-benzophenone.
One such group of substituted ethylene type aromatic stabilizers has the formula:
7 \ ~ / ~ C\ wherein R4 is -CN or an alkyl acyloxy group having 1 to 8 carbon atoms in the alkyl portion, R5 is -H, a monovalent alkyl radical having 1 to 8 carbon atoms or a phenyl radical, R6 is -H, -Cl, a monovalent alkyl radical having 1 to 8 carbon atoms or an alkyl acyloxy group having 1 to 8 carbon atoms in the alkyl portion, and R7 is an alkoxy group having 1 to 18 carbon atoms, a benzyloxy group or a phenoxy group.
Examples of such alkyl radicals having 1 to 8 carbon atoms that form the alkyl portion of the alkyl acyloxy group are methyl, ethyl, n-propyl, n-butyl, 2,2-d:imethylbutyl, 2,2-dimethylhexyl, ~ `
n-pentyl, n-hexyl, 2-ethylhexyl and n-octyl.
Examples of such monovalent alkyl radicals having 1 to 8 carbon atoms are methyl, ethyl, n-propyl, n-butyl, 2,2-dimethylbutyl, 2,2-dimethyl-hexyl, n-pentyl, n-hexyl, 2-ethylhexyl and n-octyl.
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Examples of such alkoxy groups having l to 18 carbon atoms are methyloxy, ethyloxy, n-butyloxy, 2,2-dimethyldecyloxy, n-pentyloxy, 2-ethylhexyloxy, n-octyloxy, 2,2-dimethyldecyloxy and the like.
A preferred species corresponds to the structure CH30~ CH=~ 3 which can be called dimethyl p-methoxybenzylidene-malonate.
These compounds and their preparation are well known in the art and are described in U.S.
Patent 3,706,701.
One such group of 2-hydroxyphenyl benzotri a7.01e compounds has the formula:
R3~ R2 wherein Rl and R2 may be the same or different and are hydrogen or a monovalent alkyl radical :
having 1 to 18 carbon atoms, and ~:
R3 is -H, -Cl or a monovalent alkyl radical having l to 18 carbon atoms.
Examples of monovalent alkyl radicals having 1 to 18 carbon atoms include methyl, ethyl, n-propyl, n-butyl, tertiary butyl, 2,2-dimethylbutyl, 2,2-di-methylhexyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, 2,2-dimethyloctyl, n-nonyl, n-decyl, -dodecyl, 2,2-dimethyldecyl, stearyl, tertiary-pentyl, and the like. A preferred species corresponds to the structure ~., :
l~ I /N-~
and can be called 2-(2H-benzotriazol-2-yl)-p-cresol.
These compounds and their preparation are well known in the art and are described in U. S. 3,004,896.
Polymeric photostabilizers may also be used;
for example, polymers prepared by the reaction of the following reactive stabilizer moieties:
2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4 meth-acryloxybenzophenone, 2-hydroxy-4-(2-methacryloxy-ethoxy)benzophenone, 2-hydroxy-4-(3-acryloxy-2-hy- -~
droxypropoxy)benzophenone and 2-hydroxy-4-(3-meth-acryloxy-2~hydroxypropoxy)benzophenone by themselves or with any one or more of the following reactive compounds: styrene, methyl methacrylate, methyl-acrylate, vinyl acetate, vinylidene chloride and vinyl chloride.
The ultraviolet stabilized organic composi-tions containing the stabilizers of the present invention may also contain other additives, pigments, colorants, stabilizers and th~ like. For example, ~-polyesters may also contain and generally do contain other additives such as white or colored pigments or colorants, antioxidants (such as phosphites), plasti- -~
cizers, flow aids, processing aids, polymeric modifiers and the like.
These conventional ultraviolet stabilizers may be incorporated into organic compositions by ~ -melt-blending or may be added onto the surface of an organic plastic material prior to being molded into a suitable object, or added to the surface of the 35 molded object. These materials can also be added to ~;
coatings and the like which can be applied to the surface of a molded object.
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These polyester moldable compositions can be formed into objects ~y any extrusion or injection molding means well known to th~e art. After the molding operation the molded object can be oriented by means and processes also known to the art for orienting plastics.
~ his inven-tion will be further illustrated by the following examples, although it will be under stood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.
Poly(ethylene terephthalate) (I) having an inherent viscosity of .56 and a weight average molecular weight of 40,000 g/mol does not respond well to photostabilization when the usual methods of polymer stabilization are applied; that is, disper-sion of the stabilizer in the polymer melt followed by extrusion of the polymer into sheeting. For example, pellets of I were coated with ultraviolet light stabilizers and the resulting mixtures were extruded into 15- to 30-mil thick films. These amorphous films were irradiated into a weathering device and the times to embrittlement of the films noted (Table 1). Embrittlement was determined by bending the films around a 1/8" mandrel. Improve-ments in film life were 1.7 for films stabilized with 4-(dodecyloxy)-2-hydroxybenzophenone (II) and 2.8 for films stabili~ed with 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone (III).
,. ~
, ~able_l Stability of Amorphous Poly(Ethylene Terephth~late) (I~
Films Containiny Selected Stabilizers 2 Hours to 5 Additive Embrittlement None 288 4-Dodecyloxy-2-hydroxybenzophenone (II) 480 2,2'-Dihydroxy-4,~'-dimethoxy- 816 benzophenone (III) Samples were irradiated in a weathering device.
Additive concentration is 0.6%.
Stabilized poly(ethylene terephthalate) (I) sheeting was prepared by extruding the stabilizer in the polyester at 265-275C. rrhe extruded sheeting (15- 30-mils thick) was cut into 4-in. squares and oriented at 185F. to 215F. using the Film Stretcher ~ -(T. M. Long Company, Inc., Somerville, ~ew Jersey).
Strips (1/2" x 3") of the above films were stapled to white 4" x 6" cards and irradiated in a Geopar Industries, Ludlow, Massachusetts weathering device until brittle.
We unexpectedly found that orientation (either uniaxially or biaxially) of the above films at temperatures between 185F. and 215F. greatly increased the weatherability of the films. ~he times to embrittlement of these amorphous films, regardless of the stabilizers used, were greater than 3700 hours, an improvement in film life of >13 (~able 2).
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o o o o C~ C~ ~ o o o _~ ~ A ~ A A A A J\ A A A ~ A ~ A
.CC 0~ , ~; ~ a P ~ ~ ~ ~q P P P ~ m P~ ~ p ~I ~
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N~ O O O 0 9~ 0 0 0 0 0 0 0 ~ ~ ~
a3~ P 1^~ 0~
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The percent of orientation and whether oriented uni-axially or biaxially does affect the stabilization of the crystallized oriented polye~ter film prepared from poly(ethylene terephthalate~ , as shown in Table 3. As shown by the table, the 6tability of partially crystallized sample (density of 1.36-1.39 g./ml.~ varied considerably; III sppear to be the mo6t effective commercial stabilizer te~ted ln this ~ystem.
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u o ~
JJ ~ ....
~ 0 O O
H 1~1 ~a ~,N ~ C ~ p p ~ t~ q p ~ P p~
r:J N
C
0) =~ 0O0 OO0 O0OOO
i O
~ ' .
As noted hereinabove, one prior art method for providing ultraviolet light stability to an oriented polyester film is to dye the film with a conventional stabilizer. In Example 4, we have practiced the above invention on an oriented poly-(ethylene terephthalate) (I) film and found that the resulting film is quite stable to ultraviolet light (Table 4), although not as stable as some of our formulations shown in Table 3.
~able 4 Stability of Poly(Ethylene ~ereph~ha~late) Films ~ -Dyed with a Stabilizer ' Hours to Film Embrittlement Experimental Dyed Film3 2450 Commercial Dyed Film I4 2500 Commercial Dyed Film II53200 lSamples were irradiated in a weathering device.
2Stabilizer that is primarily 2,2'-dihydroxy- `
4,4'-dimethoxybenzophenone.
3Film dyed using procedure described in U.S.
One preferred species of such 2-hydroxy-benzophenones corresponds to the structure ~H
lo 3 ~ , 12 25 and can be called 4-(dodecyloxy)-2-hydroxy-benzophenone.
One such group of substituted ethylene type aromatic stabilizers has the formula:
7 \ ~ / ~ C\ wherein R4 is -CN or an alkyl acyloxy group having 1 to 8 carbon atoms in the alkyl portion, R5 is -H, a monovalent alkyl radical having 1 to 8 carbon atoms or a phenyl radical, R6 is -H, -Cl, a monovalent alkyl radical having 1 to 8 carbon atoms or an alkyl acyloxy group having 1 to 8 carbon atoms in the alkyl portion, and R7 is an alkoxy group having 1 to 18 carbon atoms, a benzyloxy group or a phenoxy group.
Examples of such alkyl radicals having 1 to 8 carbon atoms that form the alkyl portion of the alkyl acyloxy group are methyl, ethyl, n-propyl, n-butyl, 2,2-d:imethylbutyl, 2,2-dimethylhexyl, ~ `
n-pentyl, n-hexyl, 2-ethylhexyl and n-octyl.
Examples of such monovalent alkyl radicals having 1 to 8 carbon atoms are methyl, ethyl, n-propyl, n-butyl, 2,2-dimethylbutyl, 2,2-dimethyl-hexyl, n-pentyl, n-hexyl, 2-ethylhexyl and n-octyl.
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Examples of such alkoxy groups having l to 18 carbon atoms are methyloxy, ethyloxy, n-butyloxy, 2,2-dimethyldecyloxy, n-pentyloxy, 2-ethylhexyloxy, n-octyloxy, 2,2-dimethyldecyloxy and the like.
A preferred species corresponds to the structure CH30~ CH=~ 3 which can be called dimethyl p-methoxybenzylidene-malonate.
These compounds and their preparation are well known in the art and are described in U.S.
Patent 3,706,701.
One such group of 2-hydroxyphenyl benzotri a7.01e compounds has the formula:
R3~ R2 wherein Rl and R2 may be the same or different and are hydrogen or a monovalent alkyl radical :
having 1 to 18 carbon atoms, and ~:
R3 is -H, -Cl or a monovalent alkyl radical having l to 18 carbon atoms.
Examples of monovalent alkyl radicals having 1 to 18 carbon atoms include methyl, ethyl, n-propyl, n-butyl, tertiary butyl, 2,2-dimethylbutyl, 2,2-di-methylhexyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, 2,2-dimethyloctyl, n-nonyl, n-decyl, -dodecyl, 2,2-dimethyldecyl, stearyl, tertiary-pentyl, and the like. A preferred species corresponds to the structure ~., :
l~ I /N-~
and can be called 2-(2H-benzotriazol-2-yl)-p-cresol.
These compounds and their preparation are well known in the art and are described in U. S. 3,004,896.
Polymeric photostabilizers may also be used;
for example, polymers prepared by the reaction of the following reactive stabilizer moieties:
2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4 meth-acryloxybenzophenone, 2-hydroxy-4-(2-methacryloxy-ethoxy)benzophenone, 2-hydroxy-4-(3-acryloxy-2-hy- -~
droxypropoxy)benzophenone and 2-hydroxy-4-(3-meth-acryloxy-2~hydroxypropoxy)benzophenone by themselves or with any one or more of the following reactive compounds: styrene, methyl methacrylate, methyl-acrylate, vinyl acetate, vinylidene chloride and vinyl chloride.
The ultraviolet stabilized organic composi-tions containing the stabilizers of the present invention may also contain other additives, pigments, colorants, stabilizers and th~ like. For example, ~-polyesters may also contain and generally do contain other additives such as white or colored pigments or colorants, antioxidants (such as phosphites), plasti- -~
cizers, flow aids, processing aids, polymeric modifiers and the like.
These conventional ultraviolet stabilizers may be incorporated into organic compositions by ~ -melt-blending or may be added onto the surface of an organic plastic material prior to being molded into a suitable object, or added to the surface of the 35 molded object. These materials can also be added to ~;
coatings and the like which can be applied to the surface of a molded object.
'~ .', 'j!J" ~ ' 5~
These polyester moldable compositions can be formed into objects ~y any extrusion or injection molding means well known to th~e art. After the molding operation the molded object can be oriented by means and processes also known to the art for orienting plastics.
~ his inven-tion will be further illustrated by the following examples, although it will be under stood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.
Poly(ethylene terephthalate) (I) having an inherent viscosity of .56 and a weight average molecular weight of 40,000 g/mol does not respond well to photostabilization when the usual methods of polymer stabilization are applied; that is, disper-sion of the stabilizer in the polymer melt followed by extrusion of the polymer into sheeting. For example, pellets of I were coated with ultraviolet light stabilizers and the resulting mixtures were extruded into 15- to 30-mil thick films. These amorphous films were irradiated into a weathering device and the times to embrittlement of the films noted (Table 1). Embrittlement was determined by bending the films around a 1/8" mandrel. Improve-ments in film life were 1.7 for films stabilized with 4-(dodecyloxy)-2-hydroxybenzophenone (II) and 2.8 for films stabili~ed with 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone (III).
,. ~
, ~able_l Stability of Amorphous Poly(Ethylene Terephth~late) (I~
Films Containiny Selected Stabilizers 2 Hours to 5 Additive Embrittlement None 288 4-Dodecyloxy-2-hydroxybenzophenone (II) 480 2,2'-Dihydroxy-4,~'-dimethoxy- 816 benzophenone (III) Samples were irradiated in a weathering device.
Additive concentration is 0.6%.
Stabilized poly(ethylene terephthalate) (I) sheeting was prepared by extruding the stabilizer in the polyester at 265-275C. rrhe extruded sheeting (15- 30-mils thick) was cut into 4-in. squares and oriented at 185F. to 215F. using the Film Stretcher ~ -(T. M. Long Company, Inc., Somerville, ~ew Jersey).
Strips (1/2" x 3") of the above films were stapled to white 4" x 6" cards and irradiated in a Geopar Industries, Ludlow, Massachusetts weathering device until brittle.
We unexpectedly found that orientation (either uniaxially or biaxially) of the above films at temperatures between 185F. and 215F. greatly increased the weatherability of the films. ~he times to embrittlement of these amorphous films, regardless of the stabilizers used, were greater than 3700 hours, an improvement in film life of >13 (~able 2).
'l . .
l~l3r~
o~ .. " '~.
o o o o C~ C~ ~ o o o _~ ~ A ~ A A A A J\ A A A ~ A ~ A
.CC 0~ , ~; ~ a P ~ ~ ~ ~q P P P ~ m P~ ~ p ~I ~
,~ .:
N~ O O O 0 9~ 0 0 0 0 0 0 0 ~ ~ ~
a3~ P 1^~ 0~
o T
i`
~ ~ .
~l~3~
The percent of orientation and whether oriented uni-axially or biaxially does affect the stabilization of the crystallized oriented polye~ter film prepared from poly(ethylene terephthalate~ , as shown in Table 3. As shown by the table, the 6tability of partially crystallized sample (density of 1.36-1.39 g./ml.~ varied considerably; III sppear to be the mo6t effective commercial stabilizer te~ted ln this ~ystem.
'~
,, ''`''` .
u o ~
JJ ~ ....
~ 0 O O
H 1~1 ~a ~,N ~ C ~ p p ~ t~ q p ~ P p~
r:J N
C
0) =~ 0O0 OO0 O0OOO
i O
~ ' .
As noted hereinabove, one prior art method for providing ultraviolet light stability to an oriented polyester film is to dye the film with a conventional stabilizer. In Example 4, we have practiced the above invention on an oriented poly-(ethylene terephthalate) (I) film and found that the resulting film is quite stable to ultraviolet light (Table 4), although not as stable as some of our formulations shown in Table 3.
~able 4 Stability of Poly(Ethylene ~ereph~ha~late) Films ~ -Dyed with a Stabilizer ' Hours to Film Embrittlement Experimental Dyed Film3 2450 Commercial Dyed Film I4 2500 Commercial Dyed Film II53200 lSamples were irradiated in a weathering device.
2Stabilizer that is primarily 2,2'-dihydroxy- `
4,4'-dimethoxybenzophenone.
3Film dyed using procedure described in U.S.
3,943,105.
4Martin Processing, Inc., UV-X Weatherable Film.
5Martin Processing, Inc., Martin Clear/Weather - ~`
Resistant Type UV-X Polyester Film.
The advantage of our process over the dyeing process is that we can use additives that are difficult to dye into the film because of in-sufficient solubility in the dyebath and/or because of the slow rates of diffusion of the stabilizer into ~ `
the poIymer (i.e., stabilizer IV) or polymeric~ -stabilizers. Also, we can use high molecular weight nonvolatile and nonextractable additives in our process and thereby get an improve~ent over existing -products. Further~ore, it is less costly to extrude ,:
~:
q~; s ' ~ I' h the stabilizer into the film than to use a costly dyeing, washing, and drying process.
.
Our process is applicable to other poly-esters that are capable of being formed into sheeting and fibers. For example, IV can be extruded into PETG polyester having an inherent viscosity of 0.69 and a weight average molecular weight of about 55,000 g/mol, the resulting film oriented and heat set to form a stable sheeting (Table 5). PETG polyester is a copolyester prepared from mixtures of ethylene glycol and 1,4-cyclohexane dimethanol in a molar ratio of about 80:40 to 40:80 with terephthalic acid.
Table 5 Stability of PETG Polyester Films Stabilized With 1~ 2-(2H-Benzotriazo _2-yl? 4,6-di-tert-penty~he-n Hours to Film Ty~ Embrlttlement Amorphous unoriented 1200 Amorphous, biaxially oriented (300~) >2000 Samples were irradia-ted in an Atlas Carbon-Arc Weather-Ometer.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modi~ica-tions can be effected within the spirit and scope of the invention.
;`: ` `
,. . : ~, . . .
4Martin Processing, Inc., UV-X Weatherable Film.
5Martin Processing, Inc., Martin Clear/Weather - ~`
Resistant Type UV-X Polyester Film.
The advantage of our process over the dyeing process is that we can use additives that are difficult to dye into the film because of in-sufficient solubility in the dyebath and/or because of the slow rates of diffusion of the stabilizer into ~ `
the poIymer (i.e., stabilizer IV) or polymeric~ -stabilizers. Also, we can use high molecular weight nonvolatile and nonextractable additives in our process and thereby get an improve~ent over existing -products. Further~ore, it is less costly to extrude ,:
~:
q~; s ' ~ I' h the stabilizer into the film than to use a costly dyeing, washing, and drying process.
.
Our process is applicable to other poly-esters that are capable of being formed into sheeting and fibers. For example, IV can be extruded into PETG polyester having an inherent viscosity of 0.69 and a weight average molecular weight of about 55,000 g/mol, the resulting film oriented and heat set to form a stable sheeting (Table 5). PETG polyester is a copolyester prepared from mixtures of ethylene glycol and 1,4-cyclohexane dimethanol in a molar ratio of about 80:40 to 40:80 with terephthalic acid.
Table 5 Stability of PETG Polyester Films Stabilized With 1~ 2-(2H-Benzotriazo _2-yl? 4,6-di-tert-penty~he-n Hours to Film Ty~ Embrlttlement Amorphous unoriented 1200 Amorphous, biaxially oriented (300~) >2000 Samples were irradia-ted in an Atlas Carbon-Arc Weather-Ometer.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modi~ica-tions can be effected within the spirit and scope of the invention.
;`: ` `
,. . : ~, . . .
Claims (16)
1. A process for improving the weatherability and ultraviolet light stability of polyester objects comprising (1) forming said object from a polyester extrudable composition having an inherent viscosity of at least 0.4 and a 264 psi heat deflection temperature greater than 60°C. containing about 0.01 to about 10 percent by weight of at least one monochromophoric ultraviolet light stabilizer compatible with said poly-ester composition and (2) orienting said polyester object at a temperature between 185°F. to 215°F.
thereby improving the ultraviolet stability at least twice of said unoriented object.
thereby improving the ultraviolet stability at least twice of said unoriented object.
2. A process according to Claim 1 wherein said ultraviolet light stabilizer is a member of the group consisting of 2-hydroxybenzophenone compounds, phenylbenzoates, substituted ethylene type aromatic stabilizer compounds, 2-hydroxyphenylbenzotriazole compounds and polymeric photostabilizers.
3. A process according to Claim 2 wherein said ultraviolet light stabilizer is 4-dodecyloxy-2-hydroxybenzophenone.
4. A process according to Claim 2 wherein said ultraviolet light stabilizer is 2,2'-dihydroxy-4,4'-dimethoxybenzophenol.
5. A process according to Claim 2 wherein said ultraviolet stabilizer is 2-(2H-benzotriazol-2-yl)-p-cresol.
6. A process according to Claim 2 wherein said ultraviolet light stabilizer is dimethyl(p-methoxybenzylidene) malonate.
7. A process according to Claim 2 wherein said ultraviolet stabilizer is 2(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol.
8. A process for improving the weatherability and ultraviolet light stability of polyester objects comprising (1) forming said object from a polyester extrudable composition having an inherent viscosity of at least 0.4 to about 1.6 and a 264 psi heat deflection temperature greater than 60°C. containing about 0.1 to about 3 percent by weight of at least one monochromo-phoric ultraviolet light stabilizer compatible with said polyester composition and (2) orienting said poly-ester object at a temperature between 185°F. and 215°F.
thereby improving the ultraviolet stability at least twice of said unoriented object.
thereby improving the ultraviolet stability at least twice of said unoriented object.
9. A process according to Claim 8 wherein said ultraviolet light stabilizer is a member of the group consisting of 2-hydroxybenzophenone compounds, phenylbenzoates, substituted ethylene type aromatic stabilizer compounds, 2-hydroxyphenyl-benzotriazole compounds and polymeric photostabilizers.
10. A process according to Claim 9 wherein said ultraviolet light stabilizer is 4-dodecyloxy-2-hydroxybenzophenone.
11. A process according to Claim 9 wherein said ultraviolet light stabilizer is 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.
12. A process according to Claim 9 wherein said ultraviolet stabilizer is 2-(2H-benzotriazol-2-yl)-p-cresol.
13. A process according to Claim 9 wherein said ultraviolet light stabilizer is dimethyl(p-methoxybenzylidene) malonate.
14. A process according to Claim 9 wherein said ultraviolet stabilizer is 2(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol.
15. A process for improving the weatherability and ultraviolet light stability of polyester film com-prising (1) forming a film from a polyester extrudable composition having an inherent viscosity of at least 0.4 to about 1.6 and a 264 psi heat deflection tempera-ture greater than 60°C. containing about 0.1 to about 3 percent by weight of at least one monochromophoric ultraviolet light stabilizer compatible with said poly-ester composition and (2) orienting said film at a temperature between 185°F. and 215°F. thereby improving the ultraviolet stability at least twice of the un-oriented polyester film.
16. A process for improving the weatherability and utlraviolet light stability of polyester fiber com-prising (1) forming said fiber from a polyester extrud-able composition having an inherent viscosity of at least 0.4 to about 1.6 and a 264 psi heat deflection temperature greater than 60°C. containing about 0.1 to about 3 percent by weight of at least one monochromo-phoric ultraviolet light stabilizer compatible with said polyester composition and (2) orienting said fiber at a temperature between 185°F. and 215°F. thereby improving the ultraviolet stability at least twice of the unoriented polyester fiber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US92402078A | 1978-07-12 | 1978-07-12 | |
| US924,020 | 1978-07-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1135919A true CA1135919A (en) | 1982-11-23 |
Family
ID=25449596
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000331084A Expired CA1135919A (en) | 1978-07-12 | 1979-07-04 | Oriented polyester articles having improved ultraviolet stability |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5527296A (en) |
| CA (1) | CA1135919A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02285232A (en) * | 1989-04-27 | 1990-11-22 | Tomoegawa Paper Co Ltd | Online particle size measuring method and apparatus for dry type powder producing equipment |
-
1979
- 1979-07-04 CA CA000331084A patent/CA1135919A/en not_active Expired
- 1979-07-11 JP JP8802379A patent/JPS5527296A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5527296A (en) | 1980-02-27 |
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