JP2009144319A - Method for production of nonwoven fabrics including thermoadhesive conjugate fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for production of nonwoven fabric by using short cut thermoadhesive fiber having latent crimping property by being homogeneously mixed with main fibers and subjected to thermal adhesion to obtain a nonwoven fabric having a reduced uneven tension. <P>SOLUTION: A thermoadhesive conjugate fiber without expression of crimping, which comprises polyester A having a melting point of 220°C or more and a polyester B having a flow starting temperature lower than the melting point of the polyester by 40°C or more into a side-by-side type, has latent crimping performance, a difference in intrinsic viscosity between the polyester A and the polyester B within the range of 0.05-0.15, a fiber length of 5-25 mm and a fineness of 1-10 denier, is exposed to relaxation heat treatment at a temperature at which polyester B does not melt to express the spiral crimps of 5 to 15/25 mm and then mixed with the main fiber, and the mixture is heat-treated at the melting temperature of the polyester B to bond the constructing fibers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a nonwoven fabric containing a shortcut heat-adhesive conjugate fiber.

  Synthetic fibers, particularly polyester fibers, are indispensable as garments, filling materials, and industrial materials because of their excellent dimensional stability, weather resistance, mechanical properties, and durability. However, depending on the intended use, it is desired to provide a special function. In particular, in the field of recycling automobile waste materials to recycle non-woven fabrics for vehicles, there is a strong demand for shortcut heat-bondable fibers that are mixed and thermally bonded to fibers and urethane foam contained in the waste materials.

  Conventionally, many heat-bonding fibers have been used as means for bonding main fibers. Generally, a core-sheath type composite fiber in which a low melting point polyester copolymerized with polyester as a core component and isophthalic acid (hereinafter referred to as IPA) as a sheath component is arranged, polyester as a core component, and polypropylene as a sheath component. Core-sheath type composite fiber, core-sheath type composite fiber with polyester as the core component, polyethylene as the sheath component, and heat-adhesive fiber having heat resistance include polyester as the core component and aliphatic lactone as the sheath component. Many core-sheath type composite fibers and the like in which a low-melting polyester copolymerized is disposed.

  However, since these heat-adhesive fibers have a core-sheath structure, they do not develop crimps by heat treatment, and even if they are eccentric core-sheath structure fibers, the occurrence of crimps is small. Such heat-adhesive fibers that do not sufficiently develop crimp cannot be uniformly mixed with the main fibers, fibers contained in automobile waste materials and urethane foam, and strong spots are generated in the resulting nonwoven fabric. There is a problem. In addition, when trying to produce a short cut cotton with mechanical crimping in order to uniformly mix with the main fiber, etc., if a high productivity EC cutter is used, after the mechanical crimping is applied, crimpto is added to the desired fiber. When cutting into long pieces, many problems arise in production, such as poor discharge from the rotor at the time of cutting, and bulkiness at the time of packing. On the other hand, it is possible to produce crimped shortcut cotton by using a low-productivity cutting method such as guillotine cutter, but the cost for cutting becomes high and the cost is high.

  Short-cut heat-bonding fibers that have good productivity, low cost, and excellent uniform mixing with main fibers and the like are desired.

  JP-A-4-136255

  The present invention uses a short-cut heat-adhesive fiber having a latent crimping performance that eliminates such conventional problems, uniformly mixes with the main fiber, and reduces strong spots when made into a nonwoven fabric by thermal bonding. The manufacturing method of a nonwoven fabric is provided.

  In order to achieve the above object, the present inventors focused on not crimped shortcut fibers instead of crimped shortcut fibers, and created shortcut fibers having latent crimping properties without imparting crimps in the fiber production process. In addition, the present invention, which has good productivity and can be uniformly mixed with the main fiber, has been completed by revealing the inherent crimp before the step of blending with the main fiber by preliminary heat treatment.

  That is, the present invention is a composite fiber in which a polyester A having a melting point of 220 ° C. or higher and a polyester B having a flow start temperature of 40 ° C. or lower than the melting point of the polyester A are joined in a side-by-side manner. Polyester B is a heat-adhesive conjugate fiber having a latent crimping performance of 0.05 to 0.15 in difference, fiber length of 5 to 25 mm, fineness of 1 to 10 denier, and no crimp expression. Apply relaxation heat treatment at a temperature that does not melt and develop spiral crimps of 5 to 15 pieces / 25 mm, then blend with the main fiber, heat treatment at a temperature at which polyester B melts, and heat-bond the constituent fibers together A method for producing a nonwoven fabric characterized by

  In the present invention, in the production process, without applying crimp to the heat-adhesive fiber, the latent fiber has first manifested a latent crimp in the stage before mixing with the main fiber, thereby providing the main fiber. And a non-woven fabric with good mechanical properties can be obtained.

  That is, by optimizing the intrinsic viscosity difference between the polyester polymer and the low-melting-point polyester polymer that make up the heat-adhesive fiber, a shrinkage difference is created between the constituent polymers by the relaxation heat treatment to reveal latent crimps. It is possible to obtain a heat-adhesive conjugate fiber having a spiral crimp in a specific numerical range, and when mixed with the main fiber, it is uniformly dispersed. Can be produced.

  In addition, since the heat-adhesive conjugate fiber used in the present invention does not give crimps at the fiber production stage, there is no problem in the discharge state from the EC rotor, the productivity is improved, and the bulk at the time of packing is not increased. There is an effect that the storage state is good.

  In the present invention, since a shortcut heat-adhesive conjugate fiber having latent crimping performance is used, even in the field of regenerating non-woven fabric for vehicles from automobile waste materials, the fibers in the waste materials are uniformly mixed with foamed urethane, heat Bonding is possible, and a stable nonwoven fabric can be produced.

  Hereinafter, the present invention will be described in detail. The heat-adhesive fiber used in the present invention includes polyester A having a melting point (hereinafter referred to as Tm) of 220 ° C. or higher, and polyester B having a flow start temperature (hereinafter referred to as Tf) of 40 ° C. or lower than Tm of polyester A. Are composite fibers joined in a side-by-side manner. When the melting point of the polyester A is less than 220 ° C., it is difficult to stably produce the composite fiber, and even the polyester A is affected by heat during the heat-bonding process, which is not preferable. Polyester A is preferably a polyalkylene terephthalate having a Tm of 220 ° C. or higher. Examples of such polyester include polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate. Among them, productivity, mechanical properties, etc. From this point, it is preferable to use polyethylene terephthalate (hereinafter referred to as PET). Further, the polyester A may contain a small amount of an additive such as a copolymer component, a matting agent, and a lubricant as long as the characteristics are not impaired.

  Tf of polyester B is 40 ° C. or lower than Tm of polyester A. If the difference between Tf of polyester B and Tm of polyester A is less than 40 ° C., it is not economically preferable because a high temperature is required in the heat bonding treatment, and the polymer of polyester A is decomposed during the heat treatment. Is likely to occur.

  The intrinsic viscosity difference between polyester A and polyester B is in the range of 0.05 to 0.15. An intrinsic viscosity difference of less than 0.05 is not preferable because sufficient crimps are not exhibited in the relaxation heat treatment and cannot be uniformly mixed with the main fibers, fibers contained in the waste material, foamed urethane, and the like. On the other hand, when the intrinsic viscosity difference exceeds 0.15, the yarn bending angle immediately below the nozzle becomes large, and the yarn-making property is deteriorated. Even if spinning is possible and fibers are obtained, fine crimps are developed during the relaxation heat treatment, which is not preferable because it cannot be uniformly mixed with the main fibers, fibers contained in the waste material, foamed urethane, and the like.

  Polyester B is not particularly limited as long as it satisfies the above characteristics, and examples thereof include polyalkylene terephthalate copolymerized with isophthalic acid, aliphatic dicarboxylic acid, aliphatic diol and the like. Among them, polyethylene terephthalate obtained by copolymerizing 20 to 40 mol% of isophthalic acid is preferable. In fields where heat resistance is required, polyalkylene terephthalate obtained by copolymerizing 10 to 20 mol% of an aliphatic lactone such as ε-caprolactone is preferable.

  The composite form of the heat-adhesive fiber is a side-by-side type. When the composite form is a core-sheath type or an eccentric type core-sheath type, it is not preferable because sufficient crimp does not appear during the relaxation heat treatment.

  In the constituent polymers of the heat-adhesive fiber in the present invention, both are polyester-based, and the two polymers are made compatible with each other so that they are peeled off at the joint interface between the two polymers in the production process. It is because it does not.

  The cross-sectional shape is not particularly limited, but is preferably a round cross-section and may be hollow.

  The fiber length of the heat-adhesive fiber is 5 to 25 mm. When the fiber length is less than 5 mm, there is no problem in discharging from the EC rotor at the time of cutting and packaging, but it is not preferable because it cannot be uniformly mixed with the main fiber, the fiber contained in the waste material, and urethane foam. On the other hand, if the fiber length exceeds 25 mm, it is not preferable because it cannot be uniformly mixed with the main fibers. Further, the discharge from the EC rotor at the time of cutting becomes poor, and the packaging weight is reduced, resulting in an increase in manufacturing cost.

  The fineness of the heat-adhesive fiber is 1 to 10 denier. When the fineness is less than 1 denier, there is no problem in discharging and packing from the EC rotor at the time of cutting, but it is not preferable because the yarn bending angle immediately below the nozzle is increased and the yarn-making property is deteriorated. When the fineness exceeds 10 denier, there is no problem in discharging from the EC rotor at the time of cutting, but it becomes bulky at the time of packing, and the mixed state with the main fibers and the like becomes worse. Furthermore, when mixed with the main fiber, foamed urethane, etc., the denier of the heat-adhesive fiber is thick, so the number of constituents of the heat-adhesive fiber is reduced, and the contact area between the heat-adhesive fiber and the main fiber is reduced. Since it decreases, the strength of the resulting nonwoven fabric decreases, which is not preferable.

  In the heat-adhesive conjugate fiber having latent crimping performance in the present invention, a polymer of polyester A and a polymer of polyester B are melted by a commonly used two-component type composite spinning apparatus, and a side-by-side type is obtained. It can be obtained by scooping using a spinneret, performing no-crimp stretching, and then cutting the no-crimp tow into a cut length of 5 to 25 mm depending on the application. The heat-adhesive conjugate fiber of the present invention thus obtained has the advantage that it has good productivity and does not become bulky during packaging because it is not crimped.

  In the present invention, when the heat-adhesive conjugate fiber is mixed with the main fiber to form a nonwoven fabric, before the mixing step, a relaxation heat treatment is performed at a temperature at which the polyester B does not melt, and 5 to 15 pieces / 25 mm spiral crimp is expressed. Let By applying a specific number of spiral crimps, it is possible to uniformly mix with the main fibers and obtain a nonwoven fabric without strong spots.

  If the number of crimps of spiral crimp expressed by the relaxation heat treatment is less than 5/25 mm, it is not preferable because it cannot be uniformly mixed with the main fiber, the fibers contained in the waste material, foamed urethane and the like. On the other hand, if the number of crimps exceeds 15 pieces / 25 mm, the opening property is deteriorated, and it is not preferable because it cannot be uniformly mixed with the main fibers, the fibers contained in the waste material, and the urethane foam.

  The relaxation heat treatment expresses the above-described crimp, and, for example, the latent crimp is made apparent by performing heat treatment at 60 ° C. for 15 minutes using a heat treatment machine such as a hot air drier.

  Next, the non-woven fabric is formed by blending the above-mentioned latent adhesive crimped fiber with the heat-adhesive conjugate fiber, the main fiber, etc., and performing thermal bonding at a temperature at which the polyester B melts, and thermally bonding the constituent fibers together. Obtainable.

  Examples of the main fiber include ordinary synthetic fibers such as polyester. Moreover, in order to use in the field | area which reproduces the nonwoven fabric for vehicles (soundproof use etc.) from the waste material of a motor vehicle, it is preferable to use the fiber and foaming urethane which are contained in the waste material of a motor vehicle as a main fiber.

  When mixing with the main fiber, 10% by weight or more of the heat-adhesive conjugate fiber is mixed. If the amount of the heat-adhesive conjugate fiber contained in the nonwoven fabric is less than 10% by weight, the thermal bonding between the constituent fibers becomes insufficient, and the resulting nonwoven fabric has low strength, which is not preferable. The upper limit of the content of the heat-adhesive conjugate fiber may be appropriately selected according to the use. However, when the content exceeds 50% by weight, the strength of the resulting nonwoven fabric is improved, but it becomes paper-like. Therefore, it is preferable to contain 10-50 weight% of heat bondable fibers, More preferably, it is 15-30 weight%.

  After the heat-adhesive conjugate fiber and the main fiber are uniformly mixed, heat treatment is performed at a temperature at which the polyester B melts, and the constituent fibers are thermally bonded to each other. The specific heat treatment temperature is 10 from the Tf of the polyester B. The temperature is -40 ° C higher, preferably 15-25 ° C higher than Tf, and lower than Tm of polyester A.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the performance evaluation in an Example is measured according to the following method.
(1) Intrinsic viscosity: Measured at a temperature of 20 ° C. using an equal weight mixed solution of phenol and ethane tetrachloride as a solvent.

(2) Glass transition point (Tg), crystal start temperature (Tc) and melting point (Tm): A differential scanning calorimeter DSC-7 manufactured by Perkin Elmer was used and measured at a heating rate of 10 ° C./min.

(3) Tf: Using a flotester (CFT-500 type, manufactured by Shimadzu Corporation), increasing the temperature at a rate of 10 ° C./min from an initial temperature of 50 ° C. under a load of 100 kg / cm ² and a nozzle diameter of 0.5 mm. The temperature was determined as the temperature at which the polymer began to flow out of the die.

(4) Fiber length: Measured by the method of JIS L-1015-7-4-1C.

(5) Fineness: Measured by the method of JIS L-1015-7-5-1A.

(6) Number of crimps after relaxation heat treatment: Noclamptope cut into 25 mm, heat treated at 60 ° C. for 15 minutes in a state where it can be freely contracted, and then measured according to the method of JISL-1015-7-12-1. did.

(7) Spinning property: Spinning operability was evaluated in the following three stages. Δ or more was regarded as acceptable.
○: No problem in spinning operability.
Δ: Slight adhesion occurs, but there is no problem in practical use.
X: Adhesion is intense and there is a problem in spinning operability.

(8) Ejection state from EC rotor: Ejection state from EC rotor was evaluated in the following two stages.
○: There is no problem with the discharge state.
×: Emission failure.

(9) Bulky state at the time of packing: The bulky state at the time of packing was evaluated in the following two stages.
○: Bulkiness at the time of packing is satisfactory, and the state of storage in a paper bag is also good.
X: Since the bulk at the time of packing is large, storage in a paper bag is bad, and packing weight reduces.

(10) Mixed state with waste material: The mixed state with waste material was evaluated in the following two stages.
○: The mixed state with the waste material is good.
X: The mixed state with a waste material is bad, and the strength of a nonwoven fabric falls.

(11) Presence / absence of strong spots on nonwoven fabric: The presence / absence of strong spots on nonwoven fabric was evaluated in the following two stages.
○: There are no strong spots on the nonwoven fabric.
X: There are strong spots on the nonwoven fabric.

Example 1
As polyester A, PET having an intrinsic viscosity of 0.67 and Tm of 256 ° C., polyester B as copolymer of terephthalic acid / isophthalic acid = 60/40 (molar ratio), Tg of 65 ° C., Tf of 110 ° C., intrinsic viscosity of 0.57 Polymerized polyesters were prepared, and these polymers were spun at 270 ° C. in a 50:50 ratio (weight ratio) using a side-by-side type spinneret 344 holes in an ordinary two-component composite melt spinning machine, with a take-off speed of 800 m. Spinning was performed under the conditions of / min and discharge rate of 450 g / min. The obtained undrawn yarn is bundled into a bundle, drawn at a drawing temperature of 55 ° C. and a draw ratio of 3.5 times, and a finishing oil is applied to a 100,000 denier no-crimp, and a single fiber fineness of 4 denier Crimptow was obtained. The obtained noclamptow was cut into a fiber length of 15 mm and packed in a paper bag.

  Next, the heat-adhesive conjugate fiber was subjected to a relaxation heat treatment at 60 ° C. for 15 minutes immediately before mixing with the waste material, thereby revealing latent crimps and developing spiral crimps. Non-woven fabric by crimping the heat-adhesive composite fiber / fibers contained in the waste material, urethane foam = 20/80 (weight ratio) and mixing with a continuous heat treatment machine at 130 ° C for 5 minutes Got.

  The yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots on the nonwoven fabric.

  Examples 2-3 and Comparative Examples 1-2 Examples 2-3 and Comparative Examples 1-2 were performed in the same manner as Example 1 except that the fineness was as shown in Table 1.

  In Examples 2 and 3, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots of the nonwoven fabric.

  In Comparative Example 1, adhesion was intense at the spinning stage, and spinning operability was poor. In Comparative Example 2, the fineness was too thick, the state of mixing with the waste material was poor, and there were strong spots on the nonwoven fabric. The evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 1.

  Examples 4-5, Comparative Examples 3-4 About Examples 4-5 and Comparative Examples 3-4, except that the intrinsic viscosity of the polymer of polyester B was changed as shown in Table 2, it was the same as Example 1. went.

  In Examples 4 and 5, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots of the nonwoven fabric.

  In Comparative Example 3, the number of crimps after heat treatment was small, so the state of mixing with the waste material was poor and there were strong spots on the nonwoven fabric. In Comparative Example 4, adhesion was intense at the spinning stage, and spinning operability was poor. Table 2 shows the evaluation results of Examples 4 to 5 and Comparative Examples 3 to 4.

  Examples 6 to 7, Comparative Examples 5 to 6 Examples 6 to 7 and Comparative Examples 5 to 6 were performed in the same manner as Example 1 except that the fiber length was changed as shown in Table 3.

  In Examples 6 and 7, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots of the nonwoven fabric.

  Since Comparative Example 5 had a short fiber length, the state of mixing with the waste material was poor, and there were strong spots on the nonwoven fabric. In Comparative Example 6, since the fiber length was long, the discharge from the EC rotor and the mixed state with the waste material were bad, and there were strong spots of the nonwoven fabric. Table 3 shows the evaluation results of Examples 6 to 7 and Comparative Examples 5 to 6.

  Examples 8 to 9, Comparative Example 7 Examples 8 to 9 and Comparative Example 7 were performed in the same manner as Example 1 except that the mixing ratio with the waste material was changed as shown in Table 4.

  In Examples 8 and 9, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots of the nonwoven fabric.

  In Comparative Example 7, since the mixing ratio of the heat-adhesive conjugate fiber was small, there were strong spots on the nonwoven fabric and the strength was low. Table 4 shows the evaluation results of Examples 8 to 9 and Comparative Example 7.

  Example 10 Example 1 was carried out in the same manner as in Example 1 except that the heat-adhesive fiber described later was used and the heat-bonding treatment of the nonwoven fabric was changed to 180 ° C. × 5 minutes.

  The heat-bondable fiber was prepared as follows. That is, the ratio of the terephthalic acid component and the ethylene glycol component obtained by the esterification reaction of terephthalic acid and ethylene glycol as polyester B is 0.1.13. Ε-caprolactone (ε-CL) was added to the PET oligomer of 15 mol% with respect to the acid component and 1,4-butanediol was added at a ratio of 50 mol% with respect to the diol component, and the esterification reaction was carried out for 1 hour. After that, tetrabutyl titanate was added as a polycondensation catalyst, a polycondensation reaction was performed at a temperature of 260 ° C. and a pressure of 1 hPa for 3 hours, and a copolymer polyester polymer having Tg of 40 ° C., Tc of 94 ° C., Tm of 160 ° C., and an intrinsic viscosity of 0.57 was obtained. Used to obtain heat-resistant noclamptow. In Example 10, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, and the mixed state with the waste material were good, and there were no strong spots on the nonwoven fabric.

  Examples 11 to 12, Comparative Examples 8 to 9 Examples 11 to 12 and Comparative Examples 8 to 9 were performed in the same manner as Example 10 except that the intrinsic viscosity of polyester B was changed as shown in Table 5.

  In Examples 11 and 12, the yarn forming property, the number of crimps after heat treatment, the discharge from the EC rotor, the bulkiness at the time of packing, the mixed state with the waste material were good, and there were no strong spots of the nonwoven fabric.

  In Comparative Example 8, the number of crimps after the heat treatment was reduced, so that the mixed state with the waste material was poor, and there were strong spots on the nonwoven fabric. In Comparative Example 9, adhesion was intense at the spinning stage, and spinning operability was poor. Table 5 shows the evaluation results of Examples 10 to 12 and Comparative Examples 8 to 9.

Claims (3)

Polyester A having a melting point of 220 ° C. or more and a polyester B having a flow start temperature of 40 ° C. or more lower than the melting point of the polyester A are joined in a side-by-side type, and the intrinsic viscosity difference between the polyester A and the polyester B is 0.05 to Heat-adhesive conjugate fiber that has a latent crimping performance of 5 to 25 mm, a fineness of 1 to 10 denier within a range of 0.15, and does not develop crimp, is subjected to relaxation heat treatment at a temperature at which polyester B does not melt 5-15 pieces / 25 mm spiral crimps are applied, then mixed with the main fiber, heat treated at a temperature at which polyester B melts, and the constituent fibers are thermally bonded to each other. Of a non-woven fabric containing a functional composite fiber. The method for producing a nonwoven fabric according to claim 1, wherein at least 10% by weight or more of the heat-adhesive conjugate fiber is mixed. The method for producing a nonwoven fabric according to claim 1 or 2, wherein the main fiber is a fiber waste material.