Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/005—Synthetic yarns or filaments
  • D04H3/007—Addition polymers
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
  • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
  • D04H3/14—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic yarns or filaments produced by welding
  • D04H3/147—Composite yarns or filaments

Definitions

• This invention relates to hot-melt-adhesive conjugate fibers and a non-woven fabric using the conjugate fibers.
• Non-woven fabrics having a basis weight of about 10 to 45 g/m 2 have been used as the surface materials for paper diaper, goods for menstruation, etc. Further, performances required for non-woven fabrics have been highly elevated, accompanying the diversification of the use applications of non-woven fabrics, and non-woven fabrics maintaining the high strength thereof in a weight as small as possible and a soft feeling have been required, and further, those abundant in the bulkiness depending upon the use applications have been required.
• the non-woven fabrics are composed of hot-melt-adhesive conjugate fibers having a small fineness, and the low melting component contributing to hot-melt-adhesion of hot-melt-adhesive conjugate fibers displays a sufficient adhesion strength and also has softness.
• hot-melt-adhesive conjugate fibers those of combinations of polypropylene/polyethylene, polyethylene terephthalate/polyethylene, and polyethylene terephthalate/poly[(ethyleneterephthalate)-co-(ethyleneisophthalate)] have been known.
• polyethylene high density polyethylene, low density polyethylene, linear low density polyethylene, etc. have been used.
• hot-melt-adhesive conjugate fibers using low density polyethylene or linear low density polyethylene as the low melting component thereof have a merit that the resulting non-woven fabric has a soft feeling, but in general, the fibers have a low stiffness due to the low density so that the strength of the resulting non-woven fabrics have a low strength and are difficultly bulky.
• Sho 63-92722 discloses hot-melt-adhesive conjugate fibers using a polyester as the high melting component and a linear low density polyethylene having a low stiffness, as the low melting component, and a hot-melt-adhesive non-woven fabric composed of the conjugate fibers, but the non-woven fabric has a low strength and bulkiness; hence the required performances aimed in the present invention are not satisfied.
• hot-melt-adhesive conjugate fibers using a high density polyethylene as the low melting component thereof they usually have a higher density and a higher stiffness than those of low density polyethylene or linear low density polyethylene, to afford a non-woven fabric having a higher strength, but the high density polyethylene as the low melting component has a higher melting point; hence in order to afford a non-woven fabric having a high strength, it is necessary to elevate the processing temperature of the fabric.
• polypropylene is particularly used as the high melting component, the bulkiness of the resulting non-woven fabric is lowered due to its heat yielding property. Further, there is a drawback that the feeling of the non-woven fabric is liable to become hard.
• the processing temperature of the non-woven fabric is preferred to be lower in the aspect of energy cost, but when the temperature is insufficient, a non-woven fabric having a sufficient strength cannot be obtained.
• Non-woven fabrics made from high density polyethylene and polypropylene are described for example in KR 9106428 (see Dement Abstract 92-371163) and FR-A 2,498,634.
• the object of the present invention is to provide a non-woven fabric having overcome the above drawbacks of the prior art, and having a high strength, a good bulkiness and a soft feeling, and also to provide hot-melt-adhesive conjugate fibers enabling to afford the above non-woven fabric.
• the present inventors have made extensive research in order to solve the above problem, and as a result, have found that when hot-melt-adhesive conjugate fibers obtained by using a specified polyethylene as the low melting component of the fibers are processed into a non-woven fabric, the resulting non-woven fabric has a high strength, a good bulkiness and a soft feeling. Thus, we have found that the aimed object can be achieved and have completed the present invention.
• the present invention has the following compositions:
• the polypropylene used as a high melting component of the hot-melt-adhesive conjugate fibers in the present invention is a crystalline polymer composed mainly of propylene and may be propylene homopolymer or a copolymer of propylene with a small quantity of another ⁇ -olefin (such as ethylene, butene-1, etc.), and is preferred to be those having a melting point of 158°C or higher, and a melt flow rate (MFR: 230°C, ASTM D1238 (L)) of 5 to 40.
• MFR melt flow rate
• Such a polymer can be obtained by polymerizing propylene (and another ⁇ -olefin) in the presence of Ziegler-Natta catalyst, Kaminski type catalyst or the like, according to a production process such as slurry method, bulk method, gas phase method, etc.
• the polyester used as another of the high melting component of the hot-melt-adhesive conjugate fibers in the present invention is a thermoplastic polyester generally used as a raw material fibers.
• it may be polyethylene terephthalate and besides, copolymers such as poly[(ethyleneterephthalate)-co-(ethyleneisophthalate), and those having a melting point of 250° to 260°C and an intrinsic viscosity of 0.5 to 1.2 (in phenol/tetrachloroethane, at 30°C) are preferred.
• the polyethylene used in the present invention it is necessary to adjust its density to 0.950 to 0.965 g/cm 3 . If the density exceeds 0.965 g/cm 2 , the non-woven fabric obtained from hot-melt-adhesive conjugate fibers has a high strength due to the high stiffness of the low melting component, but since the melting point of the low melting component is high, it is necessary to elevate the processing temperature of the non-woven fabric.
• the density of the polyethylene is more preferably 0.955 to 0.961 g/cm 3 .
• the density referred to herein can be measured by preparing a sample piece according to the pressing method of JIS K-6758 and measuring the piece according to the density gradient tube method of JIS K-7112.
• the Q value of the polyethylene used in the present invention is necessary to be 4.5 or less. A more preferable range is 3.7 or less. In the Q value exceeds 4.5, when the fibers are heat-treated and adhered to obtain the non-woven fabric, since the polyethylene which is a low melting component melted in the fibers has a broad molecular weight distribution; the tensile strength of the fabric lowers, so that the melt adhesion of the low melting component at the points of intersection of the fibers with each other formed by the high melting component of the fibers is insufficient; hence a non-woven fabric having a high strength cannot be obtained.
• the Q value referred to herein means the ratio of the weight average molecular weight to the number average molecular weight measured by way of gel permeation chromatography in an o-dichlorobenzene solution at 140°C.
• the polyethylene used in the present invention has a methyl branch of up to 1.5/1000 C in the molecular chain, and a methyl branch as small as 0.5/1000 C is more preferable.
• the methyl branch referred to herein means a methyl group directly branched from the main chain of the polyethylene, and methyl group directly bonded to the main chain, like an end methyl group of ethyl branch is not included therein.
• the number of methyl branches is represented by the number of methyl groups directly bonded to the main chain, per 1000 carbon atoms of the main chain of the polyethylene. Such methyl groups can be determined by way of nuclear magnetic resonance spectrum of carbon atom having a mass number of 13.
• the copolymer polyethylene is reduced in the density if not only the number of methyl branch, but also the number of branch increase. If it is intended to obtain the density range defined in the present invention, by increasing only the number of methyl branch, then the point of branch increases relative to the main chain of polyethylene, as compared with the case where a branch longer than methyl branch is used. Further, if the length of branch is short, a structure similar to a linear one is obtained, and the molecule is not compact and the viscosity at the time of melting increases to make the fluidity inferior.
• a non-woven fabric is obtained by heat-treating and adhering hot-melt-adhesive fibers using a polyethylene having a methyl branch of 1.5 or more/1000 C as the low melting point component
• the adhesion of the low melting component at the points of intersection of fibers with each other, formed by the high melting component is insufficient; hence a non-woven fabric having a high strength cannot be obtained.
• ethyl branch or branch longer than ethyl branch is preferred.
• the copolymer polyethylene satisfying the above conditions can be obtained by copolymerizing ethylene with a small quantity of an ⁇ -olefin in the presence of Ziegler-Natta catalyst, chronium oxide system catalyst, molybdenum oxide system catalyst, Kaminski type catalyst or the like, according to a production process such as conventional solution method or gas phase method or high temperature and high pressure ionic polymerization method or the like.
• a small quantity of an ⁇ -olefin herein used as a comonomer refers to propylene forming methyl branch, and 1-olefins of 4 carbon atoms or more forming a branch longer than methyl branch such as butene-1, pentene-1, hexene-1, 4-methylpentene-1, heptene-1, octene-1, nonene-1, decene-1, etc.
• the polymer may be a multicomponent consisting of not only one kind but also two or more kinds of olefins and having a density and a Q value falling within the respective ranges defined in the present invention.
• melt flow rate (MFR: 190°C, ASTM D1238 (E)) of the polyethylene used in the present invention those of about 5 to 45 are used, but those of 8 to 28 are preferably used in the aspect of easy spinning. Further, in order to prevent deterioration at the time of spinning and prevent discoloration of the resulting non-woven fabric, etc., antioxydant, light-stabilizer, heat-stabilizer and besides, coloring agent, slipping agents, surfactants, delustering agent, etc. added to usual polyolefins are blended, if necessary.
• the hot-melt-adhesive conjugate fibers of the present invention are obtained by conjugate-spinning a polypropylene or a polyester as a high melting component and a polyethylene as a low melting component into a side-by-side type or a sheath-and-core type in which the polyethylene constitutes the sheath.
• the sheath-and-core type may be either one of a concentric sheath-and-core type or an eccentric sheath-and-core type.
• the component ratio of the high melting component to the low melting component those in the range of 30/70 to 70/30 by weight are preferred, and those in the range of 40 / 60 to 65/35 are more preferred.
• Other spinning and stretching conditions may be those of conjugate fibers consisting of usual combinations of polypropylene/polyethylene or polyester/polyethylene.
• the fineness of single filament of fibers and the number of crimps have no particular limitation, but in order that the strength and feeling of the non-woven fabric are balanced, a fineness of single filament of 0.5 to 6.0 d and a number of crimps of 5 to 30 crimps/25 mm are preferred, and a fineness of single filament of 1.0 to 3.0 d and a number of crimps of 10 to 20 crimps/25 mm are more preferred.
• the non-woven fabric of the present invention is obtained by making a fiber assembly consisting only of hot-melt-adhesive conjugate fibers of the present invention or a blended fiber assembly consisting of 20% by weight or more of the hot-melt-adhesive conjugate fibers and other fibers, into a web, according to known carding process, air-laying process, dry pulp process, wet paper-making process, tow-opening process, etc., followed by heat-treating the web to hot-melt-adhere the contact points of the hot-melt-adhesive conjugate fibers.
• any of a method using a dryer such as hot air dryer, suction band dryer, yankee dryer, etc., and a method using press rolls such as flat calender roll, emboss roll, etc. can be used.
• hot air dryer or suction band dryer are preferred.
• the heat-treatment temperature is a temperature of melting point or higher of the low melting component of the conjugate fibers and a melting point or lower of the high melting component thereof, and a range of about 130° to 155°C is used.
• the basis weight of the non-woven fabric has no particular limitation, and can be varied according to use applications, but when the fabric is used as a surface material of diaper or menstruation goods, 8 to 50 g/m 2 are preferred and 10 to 30 g/m 2 are more preferred.
• fibers usable by blending with the hot-melt-adhesive conjugate fibers of the present invention those which do not cause change of properties due to the above heat treatment and inhibit the object of the present invention can be optionally used, and synthetic fibers of polyester, polyamide, polypropylene, polyethylene, etc., natural fibers of cotton, wool, etc., rayon, etc. can be illustrated.
• the non-woven fabric of the present invention since the low melting component of the hot-melt-adhesive fibers functions as a binder, if the content of the hot-melt-adhesive fibers in the fiber assembly is less than 20% by weight, the hot-melt-adhered points in the points of intersection of fibers are reduced; hence a non-woven fabric having a high strength cannot be obtained.
• the conjugate fibers and the non-woven fabrics are suitable to surface materials for paper diaper, menstruation goods, etc. and besides, they can be broadly used as living-related materials, such as medical materials such as surgical gown, civil materials such as drainage material, ground-improving material, etc., industrial materials such as oil-adsorbing material, non-woven fabrics for tray mat used for packaging fresh foods such as fibers, shellfishes, meats, etc.
• JIS L1085 (a tesing method of an interlining cloth of non-woven fabric)
• a test piece having a width of 5 cm cut off from a non-woven fabric in the fiber direction (MD) and in the direction perpendicular thereto (CD) was prepared and its break strength was measured at a gripping distance of 10 cm and at a tensile velocity of 30 ⁇ 2 cm/min. Unit: Kg/5 cm.
• a load of 10 g/cm 2 was applied to the test piece, and just thereafter its thickness A (mm) was measured.
• the strength and bulkiness of the non-woven fabric are physical properties contrary to each other, Namely, there is a tendency that when the strength is high, the bulkiness is inferior, while when the bulkiness is good, the strength is low.
• evaluation was made as follows:
• the non-woven fabric is composed of a blend of the hot-melt-adhesive conjugate fibers with other fibers, when the specific volume is 60 cm 3 /g or more and the strength of the non-woven fabric is 0.5 Kg/5 cm or higher, such a non-woven fabric was evaluated to be good.
• Conjugate fibers of a sheath-and-core type wherein a polypropylene constituted the core and a polyethylene constituted the sheath and the ratio of sheath to core is 1:1, and having a single filament denier of 7.5 d/f, were obtained by spinning under the following conditions:
• the resulting unstretched fibers were stretched to 3.75 times the original length, followed by crimping, heat-treating at 100°C in order to prevent shrinkage, and cutting the length to 51 mm to obtain a hot-melt-adhesive conjugate fiber staple.
• stretching was carried out at 90°C only in Comparaitve example 2.
• the above staple was passed through a carding machine, followed by heat-treating the resulting web at 140°C by means of a suction band dryer, to obtain a non-woven fabric having the points of intersection of the hot-melt-adhesive fibers hot-melt-adhered.
• the non-woven fabrics obtained by using conjugate fibers of Example 1 and Example 2 of the present invention have high strengths in both of the longitudinal direction (MD) and the lateral direction (CD), a good bulkiness and a good feeling.
• the non-woven fabrics obtained by using the conjugate fibers of Comparaitve examples 1 to 4 have a weak strength in the lateral direction (CD) or an inferior bulkiness or feeling.
• Conjugate fibers of a sheath-and-core type wherein a polyester constituted the core and a polyethylene constituted the sheath and the component ratio is 6:4, and having a single filament denier of 6.7 d/f were obtained by spinning under the following conditions:
• the resulting unstretched fibers were stretched to 3.3 times the original length at 90°C, followed by crimping, heat-treating at 80°C in order to prevent shrinkage and cutting to a cut length of 51 mm to obtain a hot-melt-adhesive conjugate fiber staple.
• This staple was passed through a carding machine, followed by heat-treating the resulting web at 140°C by means of a suction band dryer to obtain a non-woven fabric having the points of intersection of the hot-melt-adhesive fibers hot-melt-adhered.
• heat-treatment was carried out at 130°C.
• Table 1 and Table 2 The characteristics, non-woven fabric-making conditions of the raw material polyethylene polymer, the characteristics of the resulting non-woven fabric, etc. are shown in Table 1 and Table 2.
• the non-woven fabrics obtained by using the conjugate fibers of Comparative examples 5 to 7 had a weak strength in the lateral direction (CD) or an inferior bulkiness.
• Conjugate fibers of a side-by-side type wherein the ratio of the components was 1:1, and having a single filament denier of 12 d/f, were obtained by spinning under the following conditions:
• the resulting unstretched filaments were stretched to 4 times the original length at 110°C, followed by crimping, heat-treating at 100°C for 5 minutes in order to prevent shrinkage and cutting to a cut length of 38 mm to obtain a hot-melt-adhesive conjugate fiber staple.
• the thus obtained hot-melt-adhesive conjugate fiber staple (12 to 25% by weight) was optionally blended with a polyethylene terephthalate fiber staple having a single filament denier of 6 d/f and a filament length of 51 mm (85 to 75% by weight), followed by passing the blend through a carding machine and heat-treating the resulting web at 140°C for 5 seconds by means of a suction band dryer to obtain a non-woven fabric having the points of intersection of the hot-melt-adhesive fibers hot-melt-adhered.
• the characteristics of the raw material polyethylene, the non-woven fabric-making conditions and the characteristics of the non-woven fabric are shown in Table 1 and Table 2.
• the hot-melt-adhesive non-woven fabrics containing 20% by weight or more of the conjugate fibers of Example 6 according to the present invention are superior in the strength, bulkiness and feeling.
• the non-woven fabric obtained by using the conjugate fibers of comparative example 8 and the hot-melt-adhesive non-woven fabric of Comparative example 9 which uses the conjugate fibers of the present invention but does not contain 20% by weight or more of the conjugate fibers both have a weak, lateral strength (CD).
• the hot-melt-adhesive conjugate fibers of the present invention obtained by using a specified polyethylene as the low-melting component of conjugate fibers are processed into a non-woven fabric, a non-woven fabric having a high strength, a good bulkiness and feeling is provided.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Multicomponent Fibers (AREA)
• Nonwoven Fabrics (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Applications Claiming Priority (6)

Publications (2)

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ID=26497042

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• 1994
  • 1994-10-21 JP JP6283011A patent/JPH0874128A/ja active Pending
• 1995
  • 1995-07-03 DE DE69529123T patent/DE69529123T2/de not_active Expired - Fee Related
  • 1995-07-03 EP EP95304630A patent/EP0691427B1/en not_active Expired - Lifetime
  • 1995-07-04 BR BR9503076A patent/BR9503076A/pt not_active IP Right Cessation
  • 1995-07-04 CN CN95115004A patent/CN1069354C/zh not_active Expired - Fee Related
  • 1995-07-04 KR KR19950019376A patent/KR960004572A/ko not_active Ceased

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