JP2004270041A - Heat adhesive conjugated fiber for air-laid nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat adhesive fiber for an air-laid nonwoven fabric having good adhesion to cellulosic fibers and efficiently stably producing the nonwoven fabric having a uniform weave. <P>SOLUTION: In the heat adhesive conjugated fiber for the air-laid nonwoven fabric, a modified polyolefin prepared by carrying out graft copolymerization of a vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride or a mixed polymer of the modified polyolefin with other polymers is used as a heat adhesive component. A polymer having a higher melting point than that of the modified polyolefin is used as a fiber-forming component. Both components are composited so as to expose at least the heat adhesive component to the surface and a finish oil is applied to the fiber surface. The heat adhesive conjugated fiber is prepared by regulating the content of the vinyl monomer having the unsaturated carboxylic acid or the unsaturated carboxylic acid anhydride to 0.005-0.04 mol/kg based on the weight of the modified polyolefin, the melt index of the modified polyolefin to 15-200 g/10 min, the ratio of the heat adhesive component accounting for the conjugated fiber to 55-95 wt.%, the fiber length to 2-30 mm, the number of crimps to ≤13 peaks/25 mm, the percent crimp to ≤11%, the finish oil pickup to 0.01-0.30 wt.% and the moisture content to ≤0.5 wt.%. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermoadhesive conjugate fiber for an airlaid nonwoven fabric, and further has a good adhesiveness with a cellulosic fiber such as pulp, and is capable of efficiently and stably producing a nonwoven fabric having a uniform formation. It relates to a conjugate fiber.
[0002]
[Prior art]
Conventionally, an air-laid nonwoven fabric in which wood pulp is dry-laid, impregnated with an adhesive, and fibers are adhered to each other has been mainly used. However, in recent years, a core-sheath type heat-adhesive conjugate fiber in which a low-melting-point resin is disposed in a sheath component (heat-adhesive component) is used. There has been proposed an air-laid nonwoven fabric to which is adhered (for example, Patent Document 1).
[0003]
Further, Patent Documents 2 and 3 disclose a vinyl monomer containing at least one kind selected from unsaturated carboxylic acids or unsaturated carboxylic anhydrides as a heat-adhesive conjugate fiber having good adhesion to cellulosic fibers. The modified polyolefin graft-polymerized as a heat-adhesive component has a single fiber fineness of 0.55 to 55 dtex (0.5 to 50 denier), a fiber length of 3 to 25 mm, and a number of crimps of 5.05 to 2 mol / kg. A heat-adhesive conjugate fiber of ~ 30 has been proposed. Patent Document 4 discloses a heat-adhesive conjugate fiber containing a polyolefin obtained by graft-copolymerizing an unsaturated dicarboxylic acid or an anhydride thereof as a heat-adhesive component.
[0004]
However, the above-mentioned conventionally proposed heat-adhesive conjugate fibers, although excellent in adhesion to cellulosic fibers, have very poor spreadability and unspread on an airlaid web, There is a problem that formation is uneven. In addition, when the air-laid molding is performed by the screen method, the heat-adhesive conjugate fibers remain on the metal screen of the web former, and when the air-laid molding is performed by the picker rotor method, the heat-adhesive conjugate fibers remain. There is a problem that the productivity is extremely lowered.
[0005]
When the web made of the above-mentioned heat-adhesive conjugate fiber is heat-bonded by a heat calender method, a metal mesh or a plastic is used when heat-bonding to a metal heat roller such as an emboss roller or a flat roller by a hot air air through method. There are production problems, such as the web sticking to the net.
[0006]
[Patent Document 1]
WO 97/30223 pamphlet
[0007]
[Patent Document 2]
JP 2000-212866 A
[0008]
[Patent Document 3]
JP 2001-329432 A
[0009]
[Patent Document 4]
International Publication No. 98/45519 pamphlet
[0010]
[Problems to be solved by the invention]
The present invention has been made on the background of the above-mentioned prior art, and its object is to provide a heat-adhesive property for an air-laid nonwoven fabric capable of producing a nonwoven fabric having a good adhesion to cellulosic fibers, efficiently and stably, and a uniform formation. To provide fibers.
[0011]
[Means for Solving the Problems]
The present inventor has focused on the fact that the type of polyolefin constituting the heat-adhesive component, the composite state and shape of the heat-adhesive conjugate fiber greatly affect the adhesion to pulp, The present inventors have found that even with the conjugate fiber used as the adhesive component, the adhesiveness to pulp does not deteriorate, and at the same time, an air-laid nonwoven fabric of excellent quality can be obtained efficiently, and the present invention has been achieved.
[0012]
Thus, according to the present invention, a modified polyolefin in which a vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic anhydride is graft-copolymerized, or a mixed polymer of the modified polyolefin and another polymer is used as a heat-adhesive component. A heat-adhesive conjugate fiber in which a polymer having a melting point higher than that of the modified polyolefin is used as a fiber-forming component, and both components are compounded so that at least the heat-adhesive component is exposed on the surface; Are provided, and the following (1) to (7) are satisfied, and a thermoadhesive conjugate fiber for an airlaid nonwoven fabric is provided.
(1) The content of the vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is 0.005 to 0.04 mol / kg based on the weight of the heat-adhesive component.
(2) The melt index of the heat-adhesive component is 15 to 200 g / 10 min.
(3) The ratio of the heat-adhesive component to the composite fiber is 55 to 95% by weight.
(4) The fiber length is 2 to 30 mm
(5) The number of crimps is 13 peaks / 25 mm or less, and the crimp rate is 11% or less.
(6) Oil adhesion rate of 0.01 to 0.30% by weight
(7) Moisture percentage is 0.5% by weight or less
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
First, in order to clarify the function of the heat-adhesive conjugate fiber (hereinafter, simply referred to as conjugate fiber) of the present invention, an outline of an example of an air-laid nonwoven fabric manufacturing process will be described.
[0014]
Cellulose fibers such as pulp, which is the substrate of the nonwoven fabric, are pulverized into fibers by a pulverizer. The pulverized cellulosic fibers are sent to a cotton circulation duct. On the other hand, the conjugate fiber is fed into a fiber opening machine, spread to a uniform state, and then sent to a cotton feeding circulation duct. The conjugate fiber and the cellulosic fiber are mixed in a cotton circulation duct and supplied to an air laid machine. The mixed fiber is discharged from a flat screen provided in the air laid machine or a small hole screen portion on a rotating cylindrical screen (forming drum) surface, sucked by a suction device, and a laminated fiber assembly. Become. Subsequently, the obtained laminated fiber aggregate is subjected to a heat treatment by a method such as a hot air drier, a flat calender heat roller, an emboss calender heat roller or the like to be thermally bonded. By performing the heat treatment at a temperature equal to or higher than the melting point of the heat-adhesive component, the heat-adhesive component of the conjugate fiber is melted and the conjugate fibers are heat-bonded to each other or to the intersection between the conjugate fiber and the cellulosic fiber, thereby forming a nonwoven fabric.
[0015]
The composite fiber of the present invention is a modified polyolefin in which a vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is copolymerized, or a mixed polymer of the modified polyolefin and another polymer as a heat-adhesive component, A heat-adhesive conjugate fiber containing a polymer having a higher melting point than the modified polyolefin as a fiber-forming component.
[0016]
Specific examples of the vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride include maleic anhydride, maleic acid, acrylic acid, methacrylic acid, and the like. By copolymerizing these vinyl monomers with polyolefin, the affinity with the hydroxyl groups on the surface of the cellulosic fiber can be improved. In particular, maleic anhydride has very good adhesion to cellulose fibers because the carboxylic anhydride groups are cleaved and covalently bond with the hydroxyl groups on the surface of the cellulose fibers. The following effects can be obtained. Further, since the copolymerization amount can be reduced in this way, it is advantageous in that the friction between the composite fibers or between the composite fiber and the metal can be reduced.
[0017]
Examples of the modified polyolefin backbone copolymer obtained by copolymerizing the vinyl monomer include polyethylene, polypropylene, and polybutene-1. As the polyethylene, high-density, linear low-density, low-density polyethylene can be used. These polymers may be homopolymers or copolymers with other olefins. Among these polymers, polyethylene is preferable in consideration of the range of the melting point and the ease of the graft reaction.
[0018]
Graft copolymerization of the above-mentioned vinyl monomer with the above-mentioned backbone polymer can be carried out by a usual method. Using a radical initiator, an unsaturated carboxylic acid or an unsaturated carboxylic anhydride and a vinyl monomer are mixed with a polyolefin. Then, a side chain composed of a random copolymer can be introduced, or a side chain composed of a block copolymer can be introduced by sequentially polymerizing different kinds of monomers.
[0019]
Further, in addition to the above-mentioned vinyl monomers, styrenes such as styrene and α-methylstyrene, methacrylates such as methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, and dimethylaminoethyl methacrylate are also used as the trunk polymer. Or a similar vinyl monomer such as an acrylate ester.
[0020]
The polymer constituting the heat-adhesive component may be the modified polyolefin alone or a mixed polymer of the modified polyolefin and another polymer. Here, the other polymer is preferably a polyolefin, and more preferably a polyolefin of the same type as the modified polyolefin backbone polymer. That is, when the trunk polymer is polyethylene, it is preferable that the other polymers are also polyethylene.
[0021]
Examples of the polymer constituting the fiber-forming component of the present invention, which has a higher melting point than the heat-adhesive component, include the above-mentioned modified polyolefin backbone polymer and crystalline polymers such as polyester and polyamide. In particular, polyester, especially polyethylene terephthalate, is preferable since it tends to make the texture of the nonwoven fabric uniform and can increase the spinning amount.
[0022]
The polymer used for the heat-adhesive component and the fiber-forming component described above further includes an antioxidant, a light stabilizer, an ultraviolet absorber, a neutralizer, a nucleating agent, as long as the effects of the present invention are not impaired. If necessary, additives such as an epoxy stabilizer, a lubricant, an antibacterial agent, a flame retardant, an antistatic agent, a pigment, and a plasticizer may be contained.
[0023]
The conjugate fiber of the present invention is a conjugate fiber in which at least the heat-adhesive component is exposed on the surface of the fiber, in which the heat-adhesive component and the fiber-forming component are conjugated in a parallel type, It is a composite fiber in which the component is a sheath component, the fiber-forming component is a core component, and both components are complexed into a sheath-core type or an eccentric sheath-core type. In the conjugate fiber of the present invention, a high adhesive strength is exhibited even if the ratio of the heat-adhesive component to the fiber surface is small, but it is particularly preferable to form a core-sheath composite in that pulp can be uniformly wetted. preferable.
[0024]
In the present invention, it is important that the above-mentioned conjugate fiber simultaneously satisfies the above-mentioned requirements (1) to (7). Thereby, combined with the effects of the above requirements, both the problems of improving the adhesiveness with the cellulosic fiber and efficiently producing an air-laid nonwoven fabric having a uniform formation can be achieved at the same time. .
[0025]
In other words, in the conventional technology, the content of the vinyl monomer having the unsaturated carboxylic acid or the anhydride of the unsaturated carboxylic acid in the modified polyolefin is large, and the air-laid nonwoven fabric cannot be efficiently and stably produced. It was difficult to obtain a nonwoven fabric having a uniform formation. However, in the present invention, by simultaneously satisfying the requirements of (2) to (7), the content of a vinyl monomer having an unsaturated carboxylic acid or an acid anhydride of an unsaturated carboxylic acid as defined in (1) is included. Even if the ratio is reduced, high adhesiveness to the cellulosic fiber can be maintained, and at the same time, the other problem can be achieved. Hereinafter, the requirements (1) to (7) will be described.
[0026]
First, in the present invention, the content of (1) a vinyl monomer having an unsaturated carboxylic acid or an acid anhydride of an unsaturated carboxylic acid is set to 0.005 to 0.04 mol /% based on the weight of the heat adhesive component. kg. If the content exceeds 0.04 mol / kg, the friction coefficient between the fiber and the fiber and between the fiber and the metal becomes high, which causes problems such as poor opening of the airlaid web and an increase in the spinning amount. . In addition, when air-laid webs are heat-bonded by a heat calender method, to a metal heat roller such as an emboss roller or a flat roller, and when heat-bonded by a hot air air-through method, the web adheres to a wire mesh or a plastic net. Production troubles occur frequently. On the other hand, if the content is less than 0.005 mol / kg, the adhesiveness to the cellulosic fiber is not sufficient, and the pulp tends to fall off from the nonwoven fabric after the adhesion. A more preferred content is in the range of 0.01 to 0.035 mol / kg.
[0027]
Next, (2) the melt index (MI) of the heat bonding component needs to be 15 to 200 g / 10 minutes. When the MI is less than 15 g / 10 minutes, the fluidity lacks enough to melt and wet the surface of the cellulosic fiber sufficiently, the adhesiveness with the fiber becomes insufficient, and the pulp falls off the nonwoven fabric after bonding. The amount increases. On the other hand, when the MI exceeds 200 g / 10 minutes, the melt viscosity is too low, and it becomes difficult to perform composite spinning with the ratio of the heat-adhesive component as described later in the range of 55 to 95% by weight, and many yarn breaks occur. Become. MI is in the range of 20 to 150 g / 10 min, and more preferably in the range of 40 to 100 g / 10 min.
[0028]
Further, (3) the proportion of the heat-adhesive component in the composite fiber must be 55 to 95% by weight. If the amount is less than 55% by weight, there is not enough polymer to sufficiently wet the surface of the cellulosic fiber, so that the thermal adhesion to the cellulosic fiber pulp is not sufficient, and the amount of pulp falling off the nonwoven fabric after thermal bonding is large. When it exceeds 95% by weight, stable melt spinning of the conjugate fiber becomes difficult. The proportion is preferably in the range of 60 to 90% by weight, more preferably in the range of 65 to 80% by weight.
[0029]
Further, (4) the fiber length needs to be 2 to 30 mm. When the fiber length is less than 2 mm, it is difficult to form a network for firmly adhering the cellulosic fibers. On the other hand, when the fiber length is more than 30 mm, the spinning property from a screen or a picker rotor is deteriorated, and the productivity is reduced. Cause obstacles. In order to increase the spinning amount, it is effective to shorten the fiber length as much as possible, and 3 to 8 mm is more preferable.
[0030]
The composite fiber of the present invention may or may not be crimped. In other words, when it is desired to give the nonwoven fabric bulkiness, crimping may be provided. When it is not necessary to further improve the air opening property and the discharging ability, crimping may not be provided. However, in the present invention, (5) the number of crimps must be 13 peaks / 25 mm or less, and the crimp rate must be 11% or less. Thereby, air opening property becomes favorable and a nonwoven fabric having a uniform texture can be obtained. When the number of crimps is 13 peaks / 25 mm or the crimp rate exceeds 11%, unspread fibers are generated and the spinning amount is reduced. As a form of the crimp, a plane zigzag type or an omega type crimp included in a plane is more preferable than the spiral three-dimensional crimp in terms of the opening property.
[0031]
Further, an oil agent is attached to the conjugate fiber of the present invention, and (6) the oil agent adhesion rate needs to be in the range of 0.01 to 0.30% by weight. If the amount of the oil agent is less than 0.01% by weight, the friction between the fibers becomes large, and not only the unspreading property and the spinning amount are reduced, but also static electricity is easily generated. If the amount of the oil agent exceeds 0.30% by weight, the friction between the fibers mainly increases due to the effect of the friction of the oil agent itself, the spreadability decreases, and the adhesion to the cellulosic fiber deteriorates. . The preferable range of the oil agent adhesion rate is 0.1 to 0.25% by weight.
[0032]
(7) It is necessary to suppress the water content to 0.5% by weight or less. If the water content exceeds 0.5% by weight, the friction between the modified polyolefin and the metal constituting the screen or picker rotor is significantly increased, the spinning amount is reduced, and the productivity is reduced. The preferred moisture content is 0.3% by weight or less, more preferably 0.15% by weight or less.
[0033]
The fineness of the conjugate fiber of the present invention is not particularly limited, but is preferably in the range of 0.1 to 3 dtex because the thermal adhesion to the cellulosic fiber can be further enhanced. In particular, the finer the fineness, the more the number of components can be increased, which is advantageous in that the amount of cellulosic fibers falling off can be further suppressed.
[0034]
When the conjugate fiber of the present invention is used by mixing with a cellulosic fiber, sufficient adhesion performance can be exhibited if the conjugate fiber is contained in the airlaid nonwoven fabric in an amount of about 3 to 30% by weight.
[0035]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. Each item in the examples was measured by the following method.
[0036]
(1) Fineness
It was measured by the method described in JIS L 1015 7.5.1 Method A.
[0037]
(2) Fiber length
It was measured by the method described in JIS L 1015 7.4.1 C method.
[0038]
(3) Number of crimps, crimp rate
It was measured by the method described in JIS L 1015 7.12.
[0039]
(4) Intrinsic viscosity ([η])
The measurement was performed at a temperature of 35 ° C. using orthochlorophenol as a solvent.
[0040]
(5) Melt index (MI)
It was measured by the method described in JIS K7210 condition 4.
[0041]
(6) Glass transition point (Tg), melting point (Tm)
The measurement was performed at a heating rate of 20 ° C./min using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer.
[0042]
(7) Moisture percentage
It was measured by the method described in JIS L 1015 7.1.2.
[0043]
(8) Maximum spinning amount
The pulp / binder fiber = 80/20 (weight ratio) mixed cotton body was supplied to an air laid manufacturing apparatus (1.2 m width) manufactured by Dan Webforming International A / S (Denmark) shown in FIG. 1 to be treated. That is, the mixed cotton body was fed into the cotton feeding circulation ducts 2 and 3, and the fibers were discharged from the rotating cylindrical screens 4a and 5a. The air-laid web 6 is obtained while collecting the discharged fibers by a net conveyor 7 having a suction device 8 operating at 100 m / min. In this case, the maximum spinning amount discharged without clogging of the fibers from the forming head 1 (Kg / hour) was measured. At this time, the shape of the holes of the cylindrical screens 4a and 5a was a rectangle having a vertical length of 1.5 mm and a horizontal length of 20 mm, and the screen aperture ratio was 23%.
[0044]
(9) Unopened rate
According to the airlaid method described above, the basis weight is 35 g / m. ² An unopened lump was taken out from 10 g of the web molded by the method described above, the weight x was measured, and the unopened ratio u was calculated by the following equation. u (%) = x / 10 × 100
(10) Non-woven fabric formation
With the airlaid manufacturing apparatus shown in FIG. ² After the web formed by the above is compressed by a web compression roll 9, it is subjected to a heat treatment at 150 ° C. for 3 seconds using a suction drier 10 so that the heat-adhesive component is melt-bonded, and a nonwoven fabric 11 is produced. 12 to prepare a heat-bonded nonwoven fabric for evaluation.
[0045]
The appearance of the web is observed and evaluated according to the following criteria.
Level 1: An unspread fibrous mass and spots (shading) are not seen, and the texture is uniform.
Level 2: Unspread fibrous mass is inconspicuous, but spots (shading) can be visually confirmed.
Level 3: Unopened lumps and spots (shading) are conspicuous and have uneven texture.
[0046]
(11) Pulp shedding rate
The above-mentioned heat-bonded non-woven fabric was cut into a square having an area of 10 cm × 10 cm, the weight (W1) of the non-woven fabric was measured, and then the non-woven fabric was put into a forming drum of an air laid machine, and the forming drum, needle roll, and suction were removed. After the operation, the weight (W2) was measured after taking out from the forming drum and calculated by the following equation.
Pulp shedding rate (%) = {(W1)-(W2)} (W1) × 100
This is based on the idea that the unbonded pulp in the nonwoven fabric is beaten out by a needle roll, and the pulp released is removed by suction. A smaller one indicates better adhesion to pulp.
[0047]
[Example 1]
A high-density polyethylene (HDPE) chip having an MI of 40 g / 10 min and a Tm of 131 ° C. and a linear low-density polyethylene (LLDPE) having an MI of 80 g / 10 min and a Tm of 98 ° C. are used as a trunk polymer, and anhydrous maleic is used. Chips of modified polyethylene (MPE-1) copolymerized with 0.20 mol / kg of acid and 0.8 mol / kg of methyl acrylate were mixed at a ratio of 87:13 and melted with a twin-screw extruder. Thus, a melt-mixed polymer at 250 ° C. was obtained. The maleic anhydride content of the melt-blended polymer (the heat-adhesive component) was 0.026 mol / kg, and the MI was 43 g / 10 minutes. On the other hand, PET pellets having an intrinsic viscosity [η] of 0.61 vacuum-dried at 120 ° C. for 16 hours were melted with an extruder to obtain a molten polymer (fiber-forming component) at 280 ° C. A known core-sheath having 900 melt-hole capillaries having a diameter of 0.3 mm so that both melted polymers have a sheath component A of the former and a core component B of the latter and have a weight ratio of A: B = 65: 35. The mixture was melted and discharged from the composite spinneret. At this time, the die temperature was 285 ° C., and the discharge rate was 615 g / min. Further, the discharged polymer was air-cooled with a cooling air at 30 ° C. and wound at 1150 m / min to obtain an undrawn yarn. The undrawn yarn is drawn three times in warm water at 72 ° C., and then 0.2% by weight of an oil agent composed of lauryl phosphate potassium salt / polyoxyethylene modified silicone = 80/20 is applied. A flat zigzag type crimp having a shrinkage of 9.9 peaks / 25 mm and a crimp rate of 4.9% was provided, dried at 110 ° C., and then cut into a fiber length of 5 mm. The fineness of the obtained short fibers was 2.3 dtex, and the water content was 0.2% by weight.
[0048]
The texture of the nonwoven fabric sample prepared by the airlaid method was good and rated at level 1, and the unopened rate was 0.8% and the pulp shedding rate was good at 2.4%. The maximum spinning amount was 170 kg / hour. Also, there was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0049]
[Example 2]
A high-density polyethylene (HDPE) chip with an MI of 21 g / 10 min and a Tm of 131 ° C. and a linear low-density polyethylene (LLDPE) chip with an MI of 52 g / 10 min and a Tm of 121 ° C. have an MI of 8 g / Modified polyethylene obtained by copolymerizing linear low-density polyethylene (LLDPE) having a Tm of 98 ° C. for 10 minutes with maleic anhydride at 0.20 mol / kg and methyl acrylate at 0.8 mol / kg. The MPE-1) chips were mixed at a ratio of 50:40:10, respectively, and melted with a twin-screw extruder to obtain a melt-mixed polymer at 250 ° C. The maleic anhydride content of the melt-blended polymer (the heat-adhesive component) was 0.02 mol / kg, and the MI was 27 g / 10 minutes. On the other hand, PET pellets having an intrinsic viscosity [η] of 0.61 vacuum-dried at 120 ° C. for 16 hours were melted with an extruder to obtain a molten polymer (fiber-forming component) at 280 ° C. A well-known core-sheath having 900 both round capillaries having a diameter of 0.3 mm so that the weight ratio of A: B = 60: 40 and the weight ratio of A: B = 60: 40. The mixture was melted and discharged from the composite spinneret. At this time, the die temperature was 285 ° C., and the discharge rate was 450 g / min. Further, the discharged polymer was air-cooled with a cooling air at 30 ° C. and wound at 1150 m / min to obtain an undrawn yarn. The undrawn yarn is drawn three times in warm water at 72 ° C., and then 0.2% by weight of an oil agent composed of lauryl phosphate potassium salt / polyoxyethylene modified silicone = 80/20 is applied. A flat zigzag type crimp having a shrinkage of 10.1 peaks / 25 mm and a crimp rate of 6.3% was provided, dried at 110 ° C., and then cut into a fiber length of 5 mm. The fineness of the obtained short fibers was 1.8 decitex, and the water content was 0.17% by weight.
[0050]
The formation of the nonwoven fabric sample prepared by the airlaid method was graded at level 1, and the unopened rate was 0.8% and the pulp shedding rate was good at 1.8%. The maximum spinning amount was 160 kg / hour, and there was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0051]
[Comparative Example 1]
A high-density polyethylene (HDPE) chip having an MI of 20 g / 10 min and a Tm of 131 ° C. and a linear low-density polyethylene (LLDPE) having an MI of 8 g / 10 min and a Tm of 98 ° C. as a backbone polymer, and anhydrous maleic Modified polyethylene (MPE-1) chips in which acid was copolymerized at 0.20 mol / kg and methyl acrylate at 0.8 mol / kg were mixed at a ratio of 50:50, and melted with a twin-screw extruder. Thus, a melt-mixed polymer at 250 ° C. was obtained. The maleic anhydride content of the melt-blended polymer (the heat-adhesive component) was 0.10 mol / kg, and the MI was 13 g / 10 min. On the other hand, PET pellets having an intrinsic viscosity [η] of 0.61 vacuum-dried at 120 ° C. for 16 hours were melted with an extruder to obtain a molten polymer (fiber-forming component) at 280 ° C. A known core-sheath having 900 melt-hole capillaries having a diameter of 0.3 mm so that both melted polymers have a sheath component A of the former and a core component B of the latter and have a weight ratio of A: B = 65: 35. The mixture was melted and discharged from the composite spinneret. At this time, the die temperature was 285 ° C., and the discharge rate was 450 g / min. Further, the discharged polymer was air-cooled with a cooling air at 30 ° C. and wound at 1150 m / min to obtain an undrawn yarn. The undrawn yarn is drawn 2.8 times in warm water at 72 ° C., and then 0.2% by weight of an oil agent composed of lauryl phosphate potassium salt / polyoxyethylene modified silicone = 80/20 is applied. Then, a flat zigzag type crimp having a number of crimps of 11.1 peaks / 25 mm and a crimp rate of 7.2% was applied, dried at 110 ° C., and cut into a fiber length of 5 mm. The fineness of the obtained short fibers was 1.8 decitex, and the moisture content was 0.21% by weight.
[0052]
The pulp shedding rate of the nonwoven fabric sample prepared by the airlaid method was as good as 2.3%. However, the nonwoven fabric formation was rated at level 3, the unopened rate was 5.3%, and the maximum spinning amount was 75 kg / hour. The web adhered to the wire mesh of the net conveyor 7b of the suction dryer, and stable production was not possible.
[0053]
[Comparative Example 2]
Except that the polymer weight ratio of A: B was 45:55, the procedure was the same as in Example 1. The texture of the nonwoven fabric sample prepared by the airlaid method was good and rated at level 1, the unspread rate was 0.2%, and the maximum spinning amount was 185 kg / hour, but the pulp shedding rate was 10.1%. Met. Also, there was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0054]
[Comparative Example 3]
Example 1 was repeated except that the number of crimps was 18 peaks / 25 mm and the crimp rate was 12.5%. The pulp shedding rate of the nonwoven fabric sample prepared by the airlaid method was 2.6%, and the maximum spinning amount was 155 kg / hour, which was good. However, the nonwoven fabric was rated at level 3, with an unopened rate of 3.4%. There was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0055]
[Comparative Example 4]
The procedure was the same as in Example 1, except that the oil agent adhesion rate was 0.5% by weight. The pulp shedding rate of the nonwoven fabric sample prepared by the airlaid method was 5.6%, the maximum spinning amount was slightly worse at 130 kg / hour, the nonwoven fabric formation was rated at level 2, and the unspread rate was 2.9%. . There was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0056]
[Comparative Example 5]
Example 1 was repeated except that the water content was changed to 0.5% by weight. The pulp shedding rate of the nonwoven fabric sample prepared by the airlaid method was 2.2%, which was no problem. However, the nonwoven fabric was rated at level 2, the unspread rate was 4.9%, and the maximum spinning rate was 100 kg / hour. There was no sticking of the web to the wire mesh of the net conveyor 7b of the suction dryer.
[0057]
【The invention's effect】
The heat-adhesive conjugate fiber of the present invention not only has good adhesiveness to the cellulosic fiber, but also allows the airlaid nonwoven fabric to have a uniform texture according to the conjugate fiber. For this reason, a very high-quality nonwoven fabric can be produced from the conjugate fiber of the present invention. Further, according to the composite fiber, the spinning amount at the time of air-laid molding can be increased, and since there is no sticking to the wire mesh even by thermal bonding by a hot air air through method, it is possible to efficiently and stably produce an air-laid nonwoven fabric. , Its industrial value is extremely high. In addition, the conjugate fiber of the present invention also has an effect of providing a thermoadhesive fiber which is less expensive than the conventional one, since the denatured amount of the modified polyolefin as the heat adhesive component is small.
[Brief description of the drawings]
FIG. 1 is a side view of an apparatus for producing a nonwoven fabric of the present invention.
[Explanation of symbols]
1 Web forming head
2 Cotton circulation duct
3 Cotton circulation duct
4a Forming drum (cylindrical screen)
5a Forming drum (cylindrical screen)
4b Needle roll
5b Needle roll
6 Web
7a Net conveyor
7b Net conveyor
8 Suction device
9 Web compression roll
10 Suction dryer
11 Non-woven fabric
12 Take-up roll

Claims (4)

A modified polyolefin in which a vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic anhydride is graft-copolymerized, or a mixed polymer of the modified polyolefin and another polymer is used as a heat-adhesive component, and has a melting point higher than that of the modified polyolefin. A heat-adhesive conjugate fiber in which a high polymer is used as a fiber-forming component and both components are compounded so that at least the heat-adhesive component is exposed on the surface, and an oil agent adheres to the fiber surface, and the following (1) A heat-adhesive conjugate fiber for an airlaid nonwoven fabric, which satisfies (7).
(1) The content of the vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is 0.005 to 0.04 mol / kg based on the weight of the heat-adhesive component.
(2) The melt index of the heat-adhesive component is 15 to 200 g / 10 min. (3) The ratio of the heat-adhesive component to the composite fiber is 55 to 95% by weight.
(4) The fiber length is 2 to 30 mm
(5) The number of crimps is 13 peaks / 25 mm or less, the crimp rate is 11% or less. (6) The oil agent adhesion rate is 0.01 to 0.30% by weight.
(7) Moisture percentage is 0.5% by weight or less The heat-adhesive conjugate fiber for an airlaid nonwoven fabric according to claim 1, wherein the vinyl monomer having an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride is maleic anhydride. The heat-adhesive conjugate fiber for airlaid nonwoven fabric according to claim 1 or 2, wherein the heat-adhesive conjugate fiber is a core-sheath conjugate fiber having a heat-adhesive component as a sheath and a fiber-forming component as a core. The heat-adhesive conjugate fiber for an air-laid nonwoven fabric according to any one of claims 1 to 3, wherein the fiber-forming component is polyethylene terephthalate.

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