Polymers for imparting light resistance to fibers, highly light-resistant fibers, and process for producing the fibers

A polymer for imparting light resistance to fibers is prepared by radical polymerizing a monomer composition including a specific ultraviolet stabilizable monomer and/or ultraviolet absorptive monomer. A highly light resistant fiber includes the light resistance imparting polymer inside or on the surface of the fiber. The polymer can impart a satisfactory light resistance to fibers over a long time, and the fiber is highly resistant to light.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a polymer for imparting high light
 resistance and weather resistance (hereinafter simply referred to as
 "light resistance") to fibers. The invention further relates to a highly
 light resistant fiber containing the polymer, to a highly light resistant
 fiber having a layer containing the polymer on its surface, and to a
 process for the production of the fibers.
 2. Description of the Related Art
 Polyurethane fibers are characterized by high elasticity and are widely
 used in numerous applications such as stockings, undergarments, as well as
 swimsuits, ski suits, and other sportswear, and elastic bandages,
 artificial vessels, and other medical articles. However, such polyurethane
 fibers are poor in light resistance. Specifically, by action of
 ultraviolet rays in sunlight or light from fluorescent lamps, the
 molecules of polyurethane fibers are photolyzed, and the strength and
 other properties of the fibers are deteriorated or dyed fibers are
 discolored.
 Separately, polyester fibers are highly strong and highly elastic, are
 satisfactorily resistant to heat and chemicals, and are in wide use for
 clothing materials and industrial materials. The polyester fibers are more
 resistant to light and are therefore more resistant to light-induced
 deterioration and discoloring than polyurethane fibers and polyamide
 fibers. Demands on the use of such polyester fibers for interior members
 of cars and other materials have been increased, as such materials are
 often exposed to sunlight. However, higher light resistance is required as
 high grade cars are demanded. Improvements in light resistance of other
 fibers have been also demanded.
 To improve light resistance, light resistance improving agents such as
 ultraviolet absorbents and antioxidants which are low molecular weight
 compounds are conventionally added to fibers (e.g., Japanese Unexamined
 Patent Application Publication No. 4-153316). Such light resistance
 improving agents are added to fibers by a process which comprises the step
 of coating surfaces of fibers with the light resistance improving agents
 after the formation of fibers (surface treatment process), or by a process
 which comprises the steps of adding the light resistance improving agents
 to a spinning material prior to a spinning process, and forming fibers
 from the resulting mixture (material adding process). However, according
 to the surface treatment process, the light resistance improving agents is
 readily peeled off from the fiber and a long-term improvement effect on
 light resistance cannot be significantly expected. In addition, the
 feeling of the resulting fibers is changed and high quality products
 cannot be obtained. In contrast, the material adding process is
 disadvantageous in that in wet spinning, for example, the light resistance
 improving agents is dissolved out into a coagulation bath, and only a
 portion of the added light resistance improving agents remains in the
 fiber. In addition, such a low molecular weight light resistance improving
 agents bleeds out on the surface of the fiber and, ultimately, is peeled
 out from the fiber, and the appearance of the fiber is deteriorated with
 time.
 SUMMARY OF THE INVENTION
 Accordingly, an object of the invention is to provide a polymer which is
 capable of imparting a high light resistance to fibers over a long time,
 and to provide a highly light resistant fiber.
 Specifically, the invention provides, in an aspect, a polymer for imparting
 light resistance to fibers (hereinafter referred to as "light resistance
 imparting polymer"). The polymer is obtained by radical polymerizing a
 monomer composition including an ultraviolet stabilizable monomer of the
 following formula (1) or (2):
 ##STR1##
 wherin R.sup.1 is a hydrogen atom or a cyano group, each of R.sup.2 and
 R.sup.3 is independtly a hydrogen atom or a methyl group, R.sup.4 is a
 hydrogen atom or a hydrocarbon group, and X is an oxygen atom or an imino
 goup.
 ##STR2##
 wherin R.sup.1 is a hydrogen atom or a cyano group, each of R.sup.2,
 R.sup.3, R.sup.2 ', and R.sup.3 ' is independently a hydrogen atom or a
 methyl group, and X is an oxeygen atom or an imino group.
 In another aspect, invention provides a polymer for imparting light
 resistance to fibers. This polymer is obtained by radical polymerizing a
 monomer composition comprising an ultraviolet absorptive monomer of the
 following formula (3) or (4):
 ##STR3##
 wherein R.sup.5 is a hydrogen atom or a hydrocarbon group, R.sup.6 is an
 alkylene group, R.sup.7 is a hydrogen atom or a methyl group, and Y is a
 hydrogen atom, a halogen atom, a hydrocarbon group, an alkoxy group, a
 cyano group, or a nitro group;
 ##STR4##
 wherein R.sup.8 is an alkylene group, and R.sup.9 is a hydrogen atom or a
 methyl group.
 The invented light resistance imparting polymer may also be a mixture of a
 polymer obtained by polymerizing a monomer composition including the
 ultraviolet stabilizable monomer and a polymer obtained by polymerizing a
 monomer composition including the ultraviolet absorptive monomer.
 The invention is also related to a highly light resistant fiber containing
 the light resistance imparting polymer inside the fiber, and a highly
 light resistant fiber having a layer including the light resistance
 imparting polymer formed on its surface. In addition and advantageously,
 the invention is directed to a process for producing a highly light
 resistant fiber. This process includes the steps of blending the light
 resistance imparting polymer with a material for the production of a
 fiber, and spinning the resulting mixture.
 DESCRIPTION OF THE PREFERRED EMBODIMENT
 The invented light resistance imparting polymer for fibers is a polymer
 obtained by radical polymerizing a monomer composition comprising the
 ultraviolet stabilizable monomer of the formula (1) or (2) and/or the
 ultraviolet absorptive monomer of the formula (3) or (4), or is a mixture
 of a polymer obtained by radical polymerizing a monomer composition
 containing the ultraviolet stabilizable monomer, and a polymer obtained by
 radical polymerizing a monomer composition containing the ultraviolet
 absorptive monomer. The invented light resistance imparting polymer can
 therefore impart high light resistance to fibers. By blending the polymer
 with a material for the production of fibers prior to spinning and other
 fiber formation processes, the resulting formed fiber comprises a polymer
 chain having fiber-forming property (a polymer chain predominantly
 constitutes the fiber) entangled with a molecular chain of the light
 resistance imparting polymer on the molecular level. By this
 configuration, the bleedout and peeling off of the light resistance
 imparting polymer from the fiber surface and deterioration of appearance
 of the fiber can be significantly inhibited.
 Particularly, the conventional low molecular weight light resistance
 improving agents are readily dropped out from fibers in humid
 surroundings, but the invented light resistance imparting polymer can
 impart light resistance to fibers over a long time even in humid
 surroundings. In addition, even when fibers are produced by wet spinning,
 the light resistance imparting polymer does not dissolve into a
 coagulation bath during spinning procedure. The invention will now be
 described in further detail below.
 The invented light resistance imparting polymer is obtained by using a
 monomer composition essentially comprising a specific ultraviolet
 stabilizable monomer and/or ultraviolet absorptive monomer. The term
 "ultraviolet stabilizable monomer" means and includes monomers which do
 not belong to ultraviolet absorbents (UVAs) and do not have an ultraviolet
 absorbing property but stabilize a polymer satisfactorily against
 ultraviolet rays by a different activity or mechanism from UVAs and are
 radical polymerizable. The stabilizing activity against ultraviolet rays
 has not yet been sufficiently clarified, but this is probably because
 N-oxy radicals, which are formed by the oxidation of an N-substituent on a
 piperidine skeleton, trap alkyl radicals induced by ultraviolet rays.
 The specific ultraviolet stabilizable monomers for use in the invention
 include piperidines of the formula (1) or (2). Illustrative substituents
 R.sup.4 is a hydrogen atom or hydrocarbon groups each having 1 to 18
 carbon atoms. Such hydrocarbon groups include, but are not limited to,
 methyl group, ethyl group, propyl group, isopropyl group, butyl group,
 isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group,
 octyl group, nonyl group, decyl group, undecyl group, dodecyl group,
 tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group,
 heptadecyl group, octadecyl group, and other aliphatic hydrocarbon groups;
 cyclopropyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group,
 cyclooctyl group, and other alicyclic hydrocarbon groups; phenyl group,
 tolyl group, xylyl group, benzyl group, phenethyl group, and other
 aromatic hydrocarbon groups.
 Illustrative ultraviolet stabilizable monomers of the formula (1) include
 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine,
 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine,
 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine,
 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine,
 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidin e,
 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and
 4-crotonoylamino-2,2,6,6-tetramethylpiperidine.
 Each of these monomers can be used alone or in combination. Ultraviolet
 stabilizable monomers of the formula (1) are not limited to these
 compounds.
 Examples of ultraviolet stabilizable monomers of the formula (2) include
 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethyl piperidine,
 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tet
 ramethylpiperidine, and
 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine.
 Each of these monomers can be used alone or in combination. Ultraviolet
 stabilizable monomers of the formula (2) are not limited to these
 compounds.
 In the present invention, an ultraviolet absorptive monomer can be used as
 a constituent of the light resistance imparting polymer instead of, or
 together with, the ultraviolet stabilizable monomer. The term "ultraviolet
 absorptive monomer" as used herein means and includes monomers which can
 absorb ultraviolet rays and re-radiate its energy predominantly as
 harmless thermal energy and are radical polymerizable. Such ultraviolet
 absorptive monomers for use in the invention are benzotriazoles of the
 formula (3) or (4).
 In the formula (3), the hydrocarbon group in R.sup.5 or Y includes
 hydrocarbon groups each having 1 to 8 carbon atoms. Such hydrocarbon
 groups include, but are not limited to, methyl group, ethyl group, propyl
 group, isopropyl group, butyl group, isobutyl group, tert-butyl group,
 pentyl group, hexyl group, heptyl group, octyl group, and other linear
 chain hydrocarbon groups; cyclopropyl group, cyclopentyl group, cyclohexyl
 group, cycloheptyl group, cyclooctyl group, and other alicyclic
 hydrocarbon groups; phenyl group, tolyl group, xylyl group, benzyl group,
 phenethyl group, and other aromatic hydrocarbon groups.
 The alkylene group in R.sup.6 includes alkylene groups each having 1 to 6
 carbon atoms. Such alkylene groups includes, but are not limited to,
 methylene group, ethylene group, propylene group, butylene group,
 pentylene group, hexylene group, and other linear chain alkylene groups;
 isopropylene group, isobutylene group, sec-butylene group, tert-butylene
 group, 2,2-dimethylbutylene group, 2,3-dimethylbutylene group,
 isopentylene group, neopentylene group, and other branched chain alkylene
 groups. The halogen atom in Y is fluorine, chlorine, bromine, or iodine
 atom. The alkoxy group in Y includes alkoxy groups each having 1 to 6
 carbon atoms. Such alkoxy groups include, but are not limited to, methoxy
 group, ethoxy group, propoxy group, butoxy group, pentoxy group, and
 heptoxy group. The alkylene group in R.sup.8 includes alkylene groups each
 having 2 or 3 carbon atoms, such as ethylene group, trimethylene group,
 and propylene group.
 Illustrative ultraviolet absorptive monomers of the formula (3) include,
 but are not limited to,
 2-[2'-hydroxy-5'-(methacryloyloxymethyl)phenyl]-2H-benzotr iazole,
 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-2H-benzotri azole,
 2-[2'-hydroxy-5'-(methacryloyloxypropyl) phenyl]-2H-benzotriazole,
 2-[2'-hydroxy-5'-(methacryloyl oxyhexyl)phenyl]-2H-benzotriazole,
 2-[2'-hydroxy-3'-tert-butyl-5'-(methacryloyloxyethyl)pheny
 1]-2H-benzotriazole,
 2-[2'-hydroxy-5'-tert-butyl-3'-(methacryloyloxyethyl)
 phenyl]-2H-benzotriazole,
 2-[2'-hydroxy-5'-(methacryloyl oxyethyl)phenyl]-5-chloro-2H-benzotriazole,
 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-5-methoxy-2 H-benzotriazole,
 2-[2'-hydroxy-5'-(methacryloyloxyethyl) phenyl]-5-cyano-2H-benzotriazole,
 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-5-tert-butyl-2H-benzotriazol
 e,
 2-[2'-hydroxy-5'-(methacryloyloxyethyl) phenyl]-5-nitro-2H-benzotriazole,
 and the like.
 Each of these ultraviolet absorptive monomers of the formula (3) can be
 used alone or in combination.
 Examples of ultraviolet absorptive monomers of the formula (4) include, but
 are not limited to,
 2-[2'-hydroxy-5'-(.beta.-methacryloyloxyethoxy)-3'-tert-butylph
 enyl]-4-tert-butyl-2H-benzotriazole. Each of these ultraviolet absorptive
 monomers of the formula (4) can be used alone or in combination.
 The invented light resistance imparting polymer may be a polymer composed
 of either the specific ultraviolet stabilizable monomer alone or the
 specific ultraviolet absorptive monomer alone. To impart a satisfactory
 light resistance to fibers, the polymer is preferably composed of the both
 monomers as a portion or the whole of its components. Each of the
 ultraviolet stabilizable monomer and the ultraviolet absorptive monomer
 mentioned herein is not limited to a single species, as stated above. That
 is, the invented light resistance imparting polymer may be preferably
 obtained by polymerizing a monomer composition including both the
 ultraviolet stabilizable monomer and the ultraviolet absorptive monomer.
 The monomer composition preferably further includes a (meth)acrylate of the
 following formula (5):
 ##STR5##
 wherein R.sup.10 is a hydrogen atom or a methyl group, and Z is a
 hydrocarbon group having 4 or more carbon atoms.
 The use of the (meth)acrylic ester monomer of the formula (5) is preferred
 to improve the affinity of the resulting polymer with polyurethane fibers,
 acrylic fibers and other fibers. In the formula (5), the hydrocarbon group
 in Z includes hydrocarbon groups each having 4 or more carbon atoms. Such
 hydrocarbon groups include, but are not limited to, cyclohexyl group,
 methylcyclohexyl group, cyclododecyl group, and other alicyclic groups
 each having 4 or more carbon atoms; butyl group, isobutyl group,
 tert-butyl group, 2-ethylhexyl group, heptyl group, octyl group, nonyl
 group, decyl group, undecyl group, dodecyl group, pentadecyl group,
 octadecyl group, and other linear or branched chain alkyl groups each
 having 4 or more carbon atoms; bornyl group, isobornyl group, and other
 polycyclic hydrocarbon groups each having 4 or more carbon atoms. Of these
 groups, alicyclic hydrocarbon groups, branched chain alkyl groups, and
 linear chain alkyl groups each having 6 or more carbon atoms are desirable
 to further improve the light resistance and compatibility of polyurethane,
 acrylic polymer and other polymers.
 Illustrative (meth)acrylates of the formula (5) include, but are not
 limited to, cyclohexyl(meth)acrylate, methyl cyclohexyl(meth)acrylate,
 cyclododecyl(meth)acrylate, tert-butylcyclohexyl(meth)acrylate,
 isobutyl(meth)acrylate, tert-butyl(meth)acrylate, lauryl(meth)acrylate,
 isobornyl (meth)acrylate, stearyl(meth)acrylate, and 2-ethylhexyl
 (meth)acrylate. Each of these compounds can be used alone or in
 combination.
 The invented polymer may be prepared from an additional monomer as a
 copolymerizable component in addition to the monomers mentioned above. Any
 monomer can be used as the additional monomer as far as not deteriorating
 the advantages of the invention, i.e., imparting light resistance to
 fibers. Such additional monomers include, but are not limited to,
 (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, maleic
 anhydride, and other carboxyl group-containing unsaturated monomers;
 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid
 phosphate, 2-(meth)acryloyloxy-3-chloropropyl acid phosphate,
 2-methacryloyloxyethylphenyl phosphate, and other acid phosphate
 unsaturated monomers; hydroxyethyl (meth) acrylate, hydroxypropyl
 (meth)acrylate, caprolactone-modified hydroxy(meth)acrylates (e.g., trade
 name "PLACCEL FM", a product of Daicel Chemical Industries, Ltd., Japan),
 mono(meth)acrylate of polyester diols prepared from phthalic acid and
 propylene glycol, and other hydroxyl group-containing unsaturated
 monomers; methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,
 isopropyl (meth)acrylate, and other C.sup.1 -C.sub.6 alkyl esters of
 (meth)acrylic acid; glycidyl(meth)acrylate, and other epoxy
 group-containing unsaturated monomers; (meth)acrylamide,
 N,N'-dimethylaminoethyl(meth)acrylate, vinylpyridine, vinylimidazole, and
 other nitrogen-containing unsaturated monomers; vinyl chloride, vinylidene
 chloride, and other halogen-containing unsaturated monomers; styrene,
 a-methylstyrene, vinyltoluene, and other aromatic unsaturated monomers;
 vinyl acetate, and other vinyl esters; vinyl ethers;
 trifluoroethyl(meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate,
 and other perfluoroalkyl group-containing unsaturated monomers;
 vinyltrimethoxysilane, vinyltriethoxy silane,
 .gamma.-(meth)acryloyloxypropyltrimethoxysilane,
 .gamma.-(meth)acryloyloxypropyldimethyl dimethoxysilane,
 vinyltriacetoxysilane, vinyltrichlorosilane, and other silicon-containing
 unsaturated monomers. Each of these monomers can be used alone or in
 combination according to necessity. Preferred additional monomers are
 (meth)acrylates.
 The amount of each of the monomer constituents is not restricted. The total
 amount of the ultraviolet stabilizable monomers of the formula (1) or (2)
 is 0 to 100% by weight relative to the total weight of monomer composition
 for constituting the polymer. Naturally, when the amount of the
 ultraviolet stabilizable monomer is 0% by weight, the ultraviolet
 absorptive monomer should be essentially used. The polymer should
 essentially comprise either of these monomers to impart light resistance
 to fibers. The amount of the ultraviolet stabilizable monomer preferably
 has a lower limit of 5% by weight. The lower limit is more preferably 10%
 by weight, and most preferably 20% by weight. Large amounts of the
 ultraviolet stabilizable monomer will effectively impart light resistance
 to fibers. The amount of the ultraviolet stabilizable monomer preferably
 has an upper limit of 90% by weight. The upper limit is more preferably
 80% by weight, and most preferably 70% by weight. Excessively large
 amounts of the ultraviolet stabilizable monomer may deteriorate
 compatibility of the polymer with a resin constituent of the fiber.
 The total amount of the ultraviolet absorptive monomers of the formula (3)
 or (4) is 0 to 100% by weight relative to the total weight of monomer
 composition for constituting the polymer. As is in the ultraviolet
 stabilizable monomer, when the amount of the ultraviolet absorptive
 monomer is 0% by weight, the ultraviolet stabilizable monomer should be
 essentially used to effectively impart light resistance to fibers. A lower
 limit of the amount of the ultraviolet absorptive monomer preferably is 5%
 by weight, more preferably 10% by weight. Large amounts of the ultraviolet
 absorptive monomer will effectively impart light resistance to fibers. The
 amount of the ultraviolet absorptive monomer preferably has an upper limit
 of 95% by weight. The upper limit is more preferably 80% by weight.
 In a preferred embodiment of the invention, the ultraviolet stabilizable
 monomer and the ultraviolet absorptive monomer are used in combination to
 obtain the invented polymer. The total amount of the both monomers is
 preferably 5% by weight or more relative to the amount of the monomer
 composition. A total amount of the both monomers less than 5% by weight
 cannot satisfactorily impart light resistance to fibers. The proportions
 of the (meth)acrylate of the formula (5) and other additional monomers may
 be appropriately changed according to the type and application of the
 fiber.
 In addition to the above embodiment of the copolymerization of the
 ultraviolet stabilizable monomer and the ultraviolet absorptive monomer,
 the invented light resistance imparting polymer may be blended polymer
 obtained by blending a polymer obtained from a monomer composition
 containing the ultraviolet stabilizable monomer with a polymer obtained
 from a monomer composition containing the ultraviolet absorptive monomer.
 In this case, similar light resistance can be imparted to fibers as in the
 copolymer of the ultraviolet stabilizable monomer and the ultraviolet
 absorptive monomer, by blending the polymer contributing to high stability
 against ultraviolet rays with the polymer having an ultraviolet absorbing
 property.
 The invented light resistance imparting polymer can be prepared by
 polymerizing a monomer composition containing the above-mentioned monomers
 according to a known radical polymerization process. Such polymerization
 processes include solution polymerization, dispersion polymerization,
 suspension polymerization, emulsion polymerization, and other
 polymerization processes. When the monomer composition is polymerized
 through solution polymerization, a solvent is used. Such solvents include,
 but are not limited to, toluene, xylene, and other aromatic solvents
 having high boiling point ; butyl acetate, ethyl acetate, cellosolve
 acetate, and other ester series solvents; acetone, methyl ethyl ketone,
 methyl isobutyl ketone, and other ketone series solvents;
 dimethylacetamide, dimethylformamide, and other amide series solvents.
 Solvent is not limited to these solvents, other solvents can be used. Each
 of these solvents can be used alone or in combination. The proportion of
 the solvent can be selected within an appropriate range in consideration
 of the concentration of a polymerized product and other parameters.
 Polymerization initiators for use in the polymerization processes include,
 but are not limited to, conventional or known radical polymerization
 initiators such as
 2,2'-azobis-(2-methylbutyronitrile), tert-butylperoxy-2-ethylhexanoate,
 2,2'-azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide.
 The proportion of the polymerization initiator is not limited and may be
 selected within an appropriate range in consideration of required
 characteristics of the polymer.
 The reaction temperature is not critical, but is preferably in a range from
 room temperature to 200.degree. C., and more preferably in a range from
 40.degree. C. to 140.degree. C. The reaction time may be appropriately
 selected to complete the polymerization reaction according to the
 composition of the monomer components and the type of the polymerization
 initiator used. The polymer preferably has a number average molecular
 weight of 1000 or more. A polymer having a number average molecular weight
 less than 1000 will require a complicated polymerization technique to
 control the molecular weight. Such a polymer will have no difference in
 performances from conventional low molecular weight light resistance
 improving agents of additive type, and will cause bleedout or other
 disadvantages. In contrast, preferred upper limit of the number average
 molecular weight is 50.times.10.sup.4. A polymer having a number average
 molecular weight exceeding 50.times.10.sup.4 will require a complicated
 production operation, will be difficult to handle, and will have a
 deteriorated compatibility with a polymer for the formation of fibers. The
 number average molecular weight of the polymer is more preferably
 10.times.10.sup.4 or less, and most preferably 5.times.10.sup.4 or less.
 The invented light resistance imparting polymer can be used alone, can be
 used as a solution in a solvent, or can be mixed wi th another polymer, in
 the manner described below. Any known additive for fibers, such as an
 antistatic agent and flame retardant can be employed in addition to the
 polymer and solvent.
 Processes for imparting light resistance to fibers by the use of the
 invented light resistance imparting polymer include two processes, i.e., a
 process of incorporating the light resistance imparting polymer into a
 fiber, and a process of forming a layer containing the light resistance
 imparting polymer on the surface of a fiber. Naturally, both processes can
 be employed in combination.
 The process of incorporating the light resistance imparting polymer into a
 fiber comprises the step of mixing the light resistance imparting polymer
 into a material for the preparation of fibers prior to spinning, and the
 step of spinning the resulting mixture through a known spinning technique.
 Such spinning techniques include, for example, solution spinning, melt
 spinning, wet spinning, non-woven spinning, and gel spinning. The invented
 highly light resistant fiber can be obtained. The light resistance
 imparting polymer is free from volatility as compared with conventional
 low molecular weight light resistance improving agents of additive type,
 and the spinning operation can be performed at higher temperatures to
 improve the efficiency of spinning.
 The proportion of the light resistance imparting polymer in the highly
 light resistant fiber, preferably is in a range of 0.1 to 20% by weight. A
 proportion of the polymer in the fiber less than 0.1% by weight will fail
 to impart satisfactory light resistance to the fiber, and in contrast, a
 proportion of the polymer exceeding 20% by weight will deteriorate the
 strength and other properties of the fiber. More preferable lower limit of
 the proportion is 0.5% by weight, and most preferable lower limit is 1.0%
 by weight. More preferable upper limit of the proportion is 15% by weight,
 and most preferable upper limit is 10% by weight.
 According to the process of forming a layer containing the light resistance
 imparting polymer on the surface of a fiber, the surface layer may be
 formed by dipping the fiber previously formed in the polymer (or the
 aforementioned solution or mixture), or by coating to the surface of the
 fiber with the polymer (or the aforementioned solution or mixture). This
 process requires no spinning operation, and is capable of imparting light
 resistance to natural fibers. When a layer containing the light resistance
 imparting polymer is formed, a layer composed of the light resistance
 imparting polymer alone can be formed by appropriately selecting the
 copolymerization composition of the light resistance imparting polymer.
 Alternatively, the surface layer can be formed by mixing the light
 resistance imparting polymer with a binder composed of a known polymer
 (resin), and forming a layer from the resulting mixture in the fiber
 surface. The type of the binder resin is not critical, and the resin
 different from the material of the fiber may be employed. However, to
 improve adhesion, a similar type of resin to the material of the fiber is
 effectively employed. Specifically, a polyurethane resin for a
 polyurethane fiber, an acrylic resin for an acrylic fiber, and a polyester
 resin for a polyester fiber can be advantageously used as the binder. The
 proportion of the light resistance imparting polymer in the surface layer
 is preferably the same range as in the incorporation of the polymer in the
 fiber. The binder may further contain known additives.
 Fibrous materials for the invented fiber include, but are not limited to,
 cotton, hemp, silk, animal hair, and other natural fibers; cellulose
 fibers, protein fibers, and other regenerated fibers and semi-synthetic
 fibers; polyurethane fibers, polyester fibers, acrylic fibers, nylon
 fibers (polyamide fibers), polyolefin fibers, polyvinylchloride fibers,
 polyvinylidene chloride fibers, polyvinyl alcohol fibers, and other
 synthetic fibers. Among them, the application of the invention to
 polyurethanes which have a low light resistance can highly effectively
 improve the light resistance of the resulting polyurethane fibers, and can
 provide versatile use of the polyurethane fibers. The application to
 widely employed polyester fibers and acrylic fibers is also preferable to
 impart higher light resistance to fibers.
 The invented highly light resistant fibers can be advantageously used for
 any application of fibers, such as clothing, interior members of cars, and
 industrial materials. Particularly, the invented fibers have a
 significantly improved light resistance and are useful as fibrous
 materials for use outdoors.
 As thus described, the application of the light resistance imparting
 polymer to fibers, which polymer is obtained by radical polymerizing a
 monomer composition containing the ultraviolet stabilizable monomer and/or
 ultraviolet absorptive monomer each having a specific structure can impart
 high light resistance and weather resistance to fibers over a long time.
 The present invention will now be illustrated in more detail with reference
 to several invented examples and comparative examples below, which are not
 intended to limit the scope of the invention. All parts and percentages in
 the invented examples and comparative examples are by weight, unless
 otherwise specified.

EXAMPLE 1
 [Polymerization of Light Resistance Imparting Polymer]
 Into a 500-ml flask with a stirrer, a dropping inlet, a thermometer, a
 condenser tube, and a nitrogen gas inlet, 30 g of N,N-dimethylformamide
 (DMF) as a polymerization solvent, and 10 g of
 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-2H-benzotriazole (UVA-1)
 were placed. A nitrogen gas was supplied into the flask, and the mixture
 in the flask was heated to 120.degree. C. with stirring. A mixture of 10 g
 of UVA-1, 60 g of 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine
 (HALS-1), 20 g of cyclohexylmethacrylate (CHMA), 70 g of DMF, and 2 g of
 2,2'-azobis-(2-methylbutyronitrile) as a polymerization initiator was
 added dropwise to the mixture over 3 hours, and the resulting mixture was
 further heated for 4 hours after the completion of addition. A 50% polymer
 solution in DMF (this 50% DMF solution is hereinafter referred to as
 "light resistance imparting polymer 1") was obtained. The obtained polymer
 had a number average molecular weight of 5700.
 EXAMPLES 2 TO 8
 Each of light resistance imparting polymers 2 to 8 was prepared in the same
 manner as in Example 1, by employing a composition indicated in Table 1.
 Abbreviations in the table have the following meanings.
 HALS-1: 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine HALS-2:
 1-methacryloyl-4-methacryloylamino-2,2,6,6-tetramethylpiperidine
 UVA-1: 2-[2'-hydroxy-5'-(methacryloyloxyethyl)phenyl]-2H-benzotriazole
 UVA-2: 2-[2'-hydroxy-5'-(.beta.-methacryloyloxyethoxy)-3'-tert-butylph
 enyl]-4-tert-butyl-2H-benzotriazole
 CHMA: cyclohexyl methacrylate
 n-BMA: butyl methacrylate
 BA: butyl acrylate
 MMA: methyl methacrylate
 HEMA: 2-hydroxyethyl methacrylate
 MAA: methacrylic acid
 DMF: N,N-dimethylformamide
 Initiator: 2,2'-azobis-(2-methylbutyronitrile)
 TABLE 1
 Example
 1 2 3 4 5 6 7 8
 Initially UVA-1 10 20 40 10
 Charged UVA-2 20 10
 DMF 30 30 30 30 30 30 30
 Toluene 30
 Added UVA-1 10 20 10
 Dropwise UVA-2 5
 HALS-1 60 60 20 45 60
 HALS-2 5 10
 CHMA 20 30 60 30 30 20 20
 n-BMA 60 20
 BA 10 10 20
 MMA 30 17
 HEMA 5
 MAA 3
 Initiator 4 4 4 4 4 4 5 4
 DMF 70 70 70 70 70 70 70
 Toluene 70
 Non-volatile Content 50 49.9 50 50.1 50.2 50.1 50.3 50.1
 (wt %)
 Number Average 5700 5900 7500 5400 5800 6400 7200 6000
 Molecular Weight
 EXAMPLE 9
 A polyester diol was prepared from 1,4-butanediol and adipic acid, and was
 mixed with 4,4'-diphenylmethane diisocyanate and 1,4-butanediol in a molar
 ratio of 1:4.2:3. The resulting mixture heated at 80.degree. C. and
 another portion of 4,4'-diphenylmethane diisocyanate heated and molten at
 50.degree. C. were respectively continuously fed to a biaxial extruder by
 a fixed delivery pump to perform continuous melt polymerization of
 polyurethane. On the way in a cylinder of the extruder, 2% by weight (on
 solid basis) of the light resistance imparting polymer 1 (50% solution in
 DMF) prepared in Example 1 was added relative to the polyurethane. The
 prepared polyurethane was extruded into water. Then the polyurethane was
 cut to yield polyurethane pellets containing the light resistance
 imparting polymer 1. The prepared pellets were dehumidified and dried at
 80.degree. C. for 20 hours, and were fed to a spinning machine with a
 uniaxial extruder and spun at a temperature of 225.degree. C. at a
 spinning rate of 500 m/min. Polyurethane fiber containing the light
 resistance imparting polymer 1 was obtained.
 EXAMPLES 10 TO 15
 Polyurethane fibers containing any of the light resistance imparting
 polymers 2 to 7 prepared in Examples 2 to 7 were obtained in the same
 manner as in Example 9.
 EXAMPLE 16
 Polyurethane fiber containing the polymer 2 (2% on the basis of solid
 content relative to the polyurethane fiber) prepared in Example 2 and the
 polymer 6 (0.7% on the basis of solid content relative to the polyurethane
 fiber) prepared in Example 6 was obtained in a similar manner as in
 Example 9.
 COMATIVE EXAMPLE 1
 Comparative polyurethane fiber containing no light resistance imparting
 polymer was prepared by performing continuous melt polymerization, pellet
 preparation and spinning procedures in the same manner as in Example 9,
 except that no light resistance imparting polymer was added to a material
 in the preparation of polyurethane.
 COMATIVE EXAMPLE 2
 Comparative polyurethane fiber containing a total of 1.5% of low molecular
 weight light resistance improving agents was prepared by performing
 continuous melt polymerization, pellet preparation and spinning procedures
 in the same manner as in Example 9. In the preparation of polyurethane,
 1.0% (relative to polyurethane) of a low molecular weight hindered amine
 type light stabilizer (molecular weight: 481; trade name "MARK LA-77", a
 product of ADEKA ARGUS CHEMICAL CO., Ltd.) and 0.5% (relative to
 polyurethane) of a low molecular weight benzotriazole series ultraviolet
 absorbent (molecular weight: 447.6; trade name "TINUVIN 234", a product of
 Ciba Specialty Chemicals K.K.) were added instead of the light resistance
 imparting polymer.
 EXAMPLES 17 TO 23
 To a mixture of 1000 g of polytetramethylene ether glycol having a
 molecular weight of 1950 and 4 g of 1,4-butanediol, 250 g of
 4,4'-diphenylmethane diisocyanate was added, and the resulting mixture was
 subjected to polymerization at 85.degree. C. for 60 minutes to yield a
 prepolymer. The prepolymer was dissolved in 900 g of DMF and the resulting
 solution was cooled to 5.degree. C. To the cooled solution, a DMF solution
 containing 13.0 g of ethylenediamine, 9.64 g of 1,2-propylenediamine, and
 4.95 g of 1,2-cyclohexanediamine was added. To the resulting polymer, a
 DMF solution containing 5.29 g of monoethanolamine was added, and
 subsequently a solution of 5 g of acetic anhydride in 250 g of DMF was
 added. A material for the production of polyurethane fiber was obtained.
 To the above-prepared material, 2% (on solid basis relative to the
 polyurethane) of the light resistance imparting polymer 1 (50% solution in
 DMF) prepared in Example 1 was added. The material containing the light
 resistance imparting polymer 1 was extruded through spinnerets into a 55%
 DMF aqueous solution and was drawn six times in a boiling water, and was
 subjected to a drying operation in a hot air at 90.degree. C. and to a
 setting operation in a steam at 105.degree. C. . Polyurethane fiber was
 obtained. Likewise, polyurethane fibers each containing any of the light
 resistance imparting polymers 2 to 7 prepared in Examples 2 to 7 were
 obtained.
 EXAMPLE 24
 Polyurethane fiber containing the polymer 2 (2% on the basis of solid
 content relative to the polyurethane fiber) prepared in Example 2 and the
 polymer 6 (0.7% on the basis of solid content relative to the polyurethane
 fiber) prepared in Example 6 was obtained in a similar manner as in
 Example 17.
 COMATIVE EXAMPLE 3
 Comparative polyurethane fiber containing no light resistance imparting
 polymer was prepared in the same manner as in Example 17, except that no
 light resistance imparting polymer was added.
 COMATIVE EXAMPLE 4
 Comparative polyurethane fiber containing a total of 1.5% of low molecular
 weight light resistance improving agents was prepared by wet spinning in
 the same manner as in Example 17, except that 1.0% (relative to the
 polyurethane) of the hindered amine type light stabilizer and 0.5%
 (relative to the polyurethane) of the benzotriazole series ultraviolet
 absorbent were added to the material for the production of polyurethane
 fiber instead of the light resistance imparting polymer.
 EXAMPLE 25
 A polyurethane fiber was prepared in the same manner as in Example 17,
 except that the light resistance imparting polymer 1 was not added. The
 prepared polyurethane fiber was dipped in a mixture solution of 100 parts
 of the light resistance imparting polymer 8 prepared in Example 8 and 50
 parts of toluene for 3 minutes. The dipped fiber was then heated at
 110.degree. C. for 30 minutes. Polyurethane fiber having a layer
 containing the light resistance imparting polymer alone formed on its
 surface was obtained.
 COMATIVE EXAMPLE 5
 Polyurethane fiber was prepared in the same manner as in Example 17, except
 that the light resistance imparting polymer 1 was not added. Separately,
 to a water-soluble polyurethane resin (trade name "ELASTRON F-29", a
 product of Daiichi Kogyo Seiyaku Co., Ltd., Japan), 10% (relative to the
 water-soluble polyurethane) of the aforementioned hindered amine type
 light stabilizer and 5% (relative to the water-soluble polyurethane) of
 the benzotriazole series ultraviolet absorbent were added to yield a resin
 solution. The above-prepared polyurethane fiber was dipped in the resin
 solution, and the dipped fiber was heated at 140.degree. C. for 20
 minutes. Comparative polyurethane fiber having a resin layer containing
 the low molecular weight light resistance improving agents formed on its
 surface was obtained.
 EXAMPLES 26 TO 28
 An acrylic copolymer was synthesized from 95 parts of acrylonitrile and 5
 parts of methacrylic acid, and was dissolved in DMF to yield a material
 for the production of acrylic fiber containing the acrylic copolymer in a
 concentration of 25%. To this material, the light resistance imparting
 polymer 1 (50% solution in DMF) prepared in example 1 was added in a
 proportion of 2% on solid basis relative to the acrylic copolymer. The
 material containing the light resistance imparting polymer 1 was extruded
 through spinnerets into a 55% DMF aqueous solution and was drawn eight
 times in a boiling water, and was subjected to a drying operation in a hot
 air at 90.degree. C. and to a setting operation in a steam at 105.degree.
 C. Acrylic fiber was obtained. Likewise, acrylic fibers each containing
 any of the light resistance imparting polymers 2 and 3 prepared in
 Examples 2 and 3 were obtained.
 COMATIVE EXAMPLE 6
 Comparative acrylic fiber containing no light resistance imparting polymer
 was prepared in the same manner as in Example 26, except that the light
 resistance imparting polymer 1 was not added.
 COMATIVE EXAMPLE 7
 Comparative acrylic fiber containing a total of 1.5% of low molecular
 weight light resistance improving agents was prepared by wet spinning in
 the same manner as in Example 26, except that 1.0% (relative to the
 acrylic copolymer) of the hindered amine type light stabilizer and 0.5%
 (relative to the acrylic copolymer) of the benzotriazole series
 ultraviolet absorbent were added to the material for the production of
 acrylic fiber, instead of the light resistance imparting polymer.
 [Evaluation Methods]
 1. Durability Test
 A 5-cm sample was prepared from each of the above prepared fibers, and was
 extended at tensile speed of 50cm/min to 300% as long as original length
 (5-cm) using a tensile tester ("INSTRON 4502 TYPE"). Then, the extended
 sample was released. The extending and releasing procedures were repeated
 five times each. In the sixth extending procedure, the sample was extended
 until it was broken, and the breaking extension and breaking strength of
 the sample were measured as initial values. Separately, another 5-cm
 sample was irradiated with ultraviolet rays(UV) for 20 hours using a
 Sunshine Weather Meter, an accelerated weathering tester. The breaking
 extension and breaking strength of this sample after UV irradiation were
 determined. The extension retention ratio and strength retention ratio
 were respectively defined as the ratio of the value after UV irradiation
 to the initial value. Specifically, the retention ratio was calculated
 according to the following equation:
 The retention ratio (%) =[Value after UV irradiation/Initial
 value].times.100
 The results are shown in Tables 2 to 5. A similar test was performed on a
 sample after storage at 80.degree. C. at 98% relative humidity (RH) for 30
 hours (in the tables, indicated as "after humid storage"), and the results
 are set forth in Tables 2 and 5.
 2. Yellowing Resistance Test
 A sample was subjected to UV irradiation in 70.degree. C. for 4 hours and
 was left in a humid atmosphere at 50.degree. C. in a 4 hours, as a cycle.
 The cycle was repeated 12 times. Then the yellowing degree (.DELTA.b) of
 the sample after the 96 hours test was determined. The yellowing degree of
 the sample was calculated according to the following equation. The
 yellowing degree indicates a change from an initial yellowness.
 Yellowing degree (.DELTA.b) =(Yellowness after Test)-(Initial Yellowness)
 The results are shown in Tables 2 to 5. A similar test was performed on a
 sample after storage at 80.degree. C. at 98% relative humidity (RH) for 30
 hours (in the tables, indicated as "after humid storage"), and the results
 are set forth in Tables 2 and 5.
 In the tables below, the term "polymer" means the light resistance
 imparting polymer, and the term "agent" means the low molecular weight
 light resistance improving agent.
 TABLE 2
 Polyurethane Fiber (Melt Spinning)
 Example Comp. Ex.
 9 10 11 12 13 14 15 16 1
 2
 Polymer No. 1 2 3 4 5 6 7 2 & 6 --
 --
 Amount of Polymer (wt %) 2 2.5 4 8 2.5 3 8 2 + 0.7 --
 --
 Amount of Agent (wt %) -- -- -- -- -- -- -- -- --
 1.5
 Extention Retention 100 94 99 94 100 92 98 96 81
 91
 Ratio (%)
 Extention Retention Ratio 98 91 97 94 99 90 97 95 78
 83
 After Humid Storage (%)
 Strength Retention 95 85 92 88 94 84 94 90 36
 76
 Ratio (%)
 Strength Retention Ratio 94 85 91 86 93 83 93 89 33
 52
 After Humid Storage (%)
 Yellowing Resistance .DELTA.b 3.9 3.9 4.0 4.5 3.8 4.1 4.0 4.0 21.3
 5.9
 Yellowing Resistance 4.1 4.2 4.3 5.0 4.0 4.3 4.3 4.3 21.3
 14.5
 After Humid Storage .DELTA.b
 TABLE 3
 Polyurethane Fiber (Wet Spinning)
 Example Comp. Ex.
 17 18 19 20 21 22 23 24 3 4
 Polymer No. 1 2 3 4 5 6 7 2 & 6 -- --
 Amount of Polymer (wt %) 2 2.5 4 8 2.5 3 8 2 + 0.7 -- --
 Amount of Agent (wt %) -- -- -- -- -- -- -- -- -- 1.5
 Extention Retention 99 92 98 95 99 90 98 95 80 92
 Ratio (%)
 Extention Retention Ratio 98 91 97 94 98 89 97 93 78 86
 After Humid Storage (%)
 Strength Retention 93 83 93 87 94 83 94 88 34 73
 Ratio (%)
 Strength Retention Ratio 92 82 93 85 92 80 91 87 33 55
 After Humid Storage (%)
 Yellowing Resigtance .DELTA.b 4.0 3.9 4.1 4.7 4.1 4.3 3.9 4.3 22.3
 6.3
 Yellowing Resistance 4.2 4.3 4.2 5.2 4.4 4.6 4.5 4.6 23.5 15.1
 After Humid Storage .DELTA.b
 TABLE 4
 Polyurethane Fiber: Surface Layer Type
 Example 25 Comp. Ex. 3 Comp. Ex. 5
 Polymer No. 8 -- --
 Extention Retention Ratio (%) 90 80 84
 Extention Retention Ratio 89 78 80
 After Humid Storage (%)
 Strength Retention Ratio (%) 71 34 59
 Strength Retention Ratio After 69 33 39
 Humid Storage (%)
 Yellowing Resistance .DELTA.b 6.5 22.3 9.7
 Yellowing Resistance After 6.8 23.5 17.8
 Humid Storage .DELTA.b
 TABLE 5
 Acrylic Fiber (Wet Spinning)
 Example Comp. Ex.
 26 27 28 6 7
 Polymer No. 1 2 3 -- --
 Amount of Polymer (wt %) 2 2.5 4 -- --
 Amount of Agent (wt %) -- -- -- -- 1.5
 Extention Retention 100 91 99 86 95
 Ratio (%)
 Extention Retention 99 90 99 84 88
 Ratio After Humid
 Storage (%)
 Strength Retention 98 92 98 37 80
 Ratio (%)
 Strength Retention 96 88 95 35 60
 Ratio After Humid
 Storage (%)
 Yellowing Resistance 3.2 3.4 3.1 18.5 5.3
 .DELTA.b
 Yellowing Resistance 3.3 3.4 3.3 19.0 11.7
 After Humid Storage .DELTA.b
 Tables 2 to 5 show that the fibers containing the light resistance
 imparting polymer or the fibers having a layer of the light resistance
 imparting polymer on its surface had further higher extension retention
 ratio, strength retention ratio and yellowing resistance after the
 accelerated weathering test than comparative examples each composed of a
 fiber alone. The fibers containing conventional low molecular weight light
 resistance improving agents according to the comparative examples
 exhibited significantly deteriorated extension retention ratio, strength
 retention ratio and yellowing resistance after storage in humid
 surroundings, but the invented fibers according to the invented examples
 showed slightly deteriorated properties. The invented polymers according
 to examples can satisfactorily impart light resistance to fibers as
 compared with the use of conventional light resistance improving agents.
 Other embodiments and variations will be obvious to those skilled in the
 art, and this invention is not to be limited to the specific matters
 stated above.