JP2009024269A - Fiber cushioning material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cushioning material having excellent biodegradability, light weight and excellent rigidity. <P>SOLUTION: The fiber cushioning material includes: a fiber structure including a biodegradable fiber A of a core-sheath type conjugate fiber, and having the sheath part and the core part both of which are composed of biodegradable thermoplastic resins regulated so that the melting temperature of the biodegradable thermoplastic resin constituting the core part may be higher than that of the biodegradable thermoplastic resin constituting the sheath part, and a biodegradable fiber B constituted of a biodegradable thermoplastic resin having a melting temperature at least 20°C higher than that of the biodegradable thermoplastic resin constituting the sheath part of the biodegradable fiber A, as main constituent fibers. The fiber cushioning material satisfies the following requirements: (1) at least a part of intersection points of the biodegradable fiber A and a constituent fiber contacting therewith is fused; and (2) the constituent fiber is oriented in the thickness direction of the fiber structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fiber cushion material having excellent biodegradability, light weight and excellent rigidity.

  Polyester fibers have become indispensable in applications such as clothing and industrial materials because of their excellent dimensional stability, weather resistance, mechanical properties, and durability, and are widely used in the field of nonwoven fabrics. Yes. In fiber structures such as nonwoven fabrics used as fiber cushion materials used for roofing base materials, automobile ceiling materials, cushioning materials, etc., among the fibers constituting the fiber structure, so-called constituent fibers, substantially thermal adhesiveness Thermal bonding fibers are widely used for the purpose of bonding non-thermal fibers, that is, non-thermal bonding fibers (hereinafter referred to as matrix fibers).

  As a base material fiber of the fiber cushion material, a relatively inexpensive and excellent polyester fiber is often used, and a heat-adhesive fiber that bonds the base material fiber is also often used that uses a polyester material. For example, a core-sheath type polyester-based thermal bonding in which the core component is polyethylene terephthalate (hereinafter referred to as PET) and the sheath component is a low melting temperature copolymerized PET copolymerized with an isophthalic acid (hereinafter referred to as IPA) component. For the adhesive fiber, the copolymerization rate of the IPA component in the low melting PET copolymerized PET is designed in accordance with the temperature at which the thermally adhesive fiber is bonded.

  Generally, when the copolymerization ratio of IPA is higher than that of PET, the melting temperature measured by a differential scanning calorimeter (hereinafter referred to as DSC) of the copolymerized PET decreases. In this case, the melting temperature refers to a temperature corresponding to an endothermic peak measured by DSC. For example, when the melting temperature of PET not containing a copolymerization component (hereinafter referred to as homo-PET) is measured by DSC, it is 250 to 260 ° C. An endothermic peak is confirmed in the range, but in PET in which 20 mol% of IPA is copolymerized, the endothermic peak decreases to 210 ° C. and the range in which the endothermic peak is observed tends to be widened. Furthermore, in PET in which 40 mol% of IPA is copolymerized, the melting temperature decreases to about 110 ° C., but the melting temperature range becomes too wide, the endothermic amount at the melting temperature decreases, and a melting peak can be observed. Disappear. In this case, since the melting temperature cannot be measured by DSC, the melting temperature is measured with a melting point microscope or the like.

  On the other hand, for example, when heat-treating a cushion material using polyester fiber as a base material fiber together with the heat-adhesive fiber, the heat treatment is usually performed at a temperature of 220 ° C. or less in consideration of the heat resistance of the base material fiber. In order to cope with such a thermal bonding temperature, a method has been adopted in which the melting temperature is reduced to about 110 ° C. by using PET obtained by copolymerization of 40 mol% of IPA as a thermal bonding component (Patent Document). 1, Patent Document 2).

  In recent years, various fiber products are required to be reused from the standpoint of environmental protection, and as one of them, a method of collecting a recyclable resin and reusing it after sorting is attracting attention. However, in reality, it is difficult to recover, and advanced technology and expensive equipment are required to separate the resin. Furthermore, the current technology has a limit on the number of times it can be reused, and after 2 to 3 recycles, it must be disposed of by incineration or landfill. Remains.

  On the other hand, recently, various biodegradable polymers have been developed that separate resins in a natural environment by the action of microorganisms existing in soil and water. Among them, polylactic acid is attracting attention because of its high melting temperature and ease of handling, and various studies using it have been made.

For example, Patent Document 3 proposes a non-woven fabric using heat-bonded fibers made of polylactic acid fibers. However, in the fiber cushion material using the technique disclosed in Patent Document 3, when assembling the flat cushion material on the ceiling or the like, it is inferior in handling properties such as being easily bent when manually lifted, and necessary handling properties In order to obtain the above, there is a problem that the amount of fibers constituting the nonwoven fabric is increased to increase the density of the structure, that is, the basis weight must be increased, and the weight cannot be sufficiently reduced.
Japanese Patent Laid-Open No. 2-139466 JP-A-6-280147 JP-A-11-279920

  An object of the present invention is to solve the above-described problems, and to provide a cushioning material having excellent biodegradability, light weight and rigidity, which cannot be achieved by the prior art.

The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems. In order to achieve the above object, the present invention has the following configuration. That is, it is a core-sheath type composite fiber, the sheath part and the core part are both composed of a biodegradable thermoplastic resin, and the biodegradable thermoplastic resin constituting the core part constitutes the sheath part. A biodegradable fiber A having a melting temperature higher than that of the resin, and a biodegradable thermoplastic resin having a melting temperature at least 20 ° C. higher than that of the biodegradable thermoplastic resin constituting the sheath of the biodegradable fiber A The fiber cushion material is characterized in that it includes a fiber structure mainly composed of biodegradable fiber B and satisfies the following requirements.
(1) At least a part of the intersection between the biodegradable fiber A and the constituent fiber in contact with the biodegradable fiber A is fused. (2) The constituent fiber is oriented in the thickness direction of the fiber structure.

  ADVANTAGE OF THE INVENTION According to this invention, while exhibiting the outstanding biodegradability, the fiber cushion material excellent in lightweight and rigidity can be provided.

  Hereinafter, the present invention will be described in detail.

  In the present invention, a biodegradable thermoplastic resin is used. Examples of the biodegradable thermoplastic resin include polylactic acid, polybutylene succinate and the like, but polylactic acid is most suitable in terms of yarn-making property.

  The polylactic acid referred to in the present invention refers to a polymer obtained by polymerizing lactic acid oligomers such as lactic acid and lactide, and the optical purity of L-form or D-form is preferably 90% or more. Moreover, you may copolymerize components other than lactic acid in the range which does not impair the property of polylactic acid. The components to be copolymerized include polyethers such as polyethylene glycol, aliphatic polyesters such as polybutylene succinate and polyglycolic acid, aromatic polyesters such as polyethylene isophthalate, and hydroxycarboxylic acids, lactones, dicarboxylic acids and diols. Examples thereof include an ester bond-forming monomer.

  Polylactic acid can be produced, for example, by the methods disclosed in JP-A-6-65360, JP-A-7-173266, US Pat. No. 2,703,316 and the like. In JP-A-6-65360, it is produced by a direct dehydration condensation method in which lactic acid is subjected to dehydration polymerization in the presence of an organic solvent and a catalyst. Further, in JP-A-7-173266, it is produced by a method in which at least two homopolymers are copolymerized and transesterified in the presence of a polymerization catalyst. Furthermore, in US Pat. No. 2,703,316, lactic acid is once dehydrated to form a cyclic dimer and then produced by an indirect polymerization method in which ring-opening polymerization is performed.

  The biodegradable fiber A used in the present invention is a core-sheath type composite fiber, the sheath part and the core part are both composed of a biodegradable thermoplastic resin, and the biodegradable thermoplastic resin constituting the core part is The melting temperature is higher than that of the biodegradable thermoplastic resin constituting the sheath. A biodegradable thermoplastic resin having a melting temperature of 130 ° C. to 180 ° C. is preferably used for the sheath, and the biodegradable thermoplastic resin constituting the core is a biodegradable thermoplastic resin constituting the sheath More preferably, the melting temperature is 20 to 50 ° C. higher. When the melting temperature of the biodegradable thermoplastic resin constituting the sheath is lower than 130 ° C., the quality of the product is impaired such as remarkable fusion between single fibers during spinning, particularly spinning, and further drawing failure. If the temperature is higher than 180 ° C., a higher temperature is required during thermal processing of the nonwoven fabric, which is not economically preferable. Furthermore, when the temperature difference between the biodegradable thermoplastic resin constituting the core and the sheath is lower than 20 ° C., the core melts during the thermal processing of the nonwoven and it is impossible to ensure a sufficient thickness of the nonwoven. When the temperature is higher than 50 ° C., it may be difficult to produce the yarn.

  The composite ratio of the core-sheath-type conjugate fiber is preferably 20/80 to 80/20 from the viewpoint of yarn production, and more preferably 40/60 to 60/40 from the viewpoint of adhesiveness and high-order processability.

  The biodegradable fiber B used in the present invention is usually in a single structure form and is composed of a biodegradable thermoplastic resin. The biodegradable thermoplastic resin constituting the biodegradable fiber B needs to have a melting temperature that is at least 20 ° C. higher than that of the biodegradable thermoplastic resin constituting the sheath of the biodegradable fiber A. If the melting temperature difference is less than 20 ° C., the biodegradable fiber B, which is the base material fiber, is softened during the heat bonding process, and it becomes difficult to form the desired shape. In the present invention, from the viewpoint of separation at the time of disposal, the biodegradable thermoplastic resin constituting the sheath part and the core part of the biodegradable fiber A and the biodegradable thermoplastic resin constituting the biodegradable fiber B are provided. Any of them is preferably polylactic acid.

  The biodegradable fiber used in the present invention preferably has a fiber length in the range of 3 mm to 100 mm. If the fiber length is less than 3 mm, the ratio of cross-linking with the base fiber decreases, and the rigidity of the structure is inferior. On the other hand, if the fiber length exceeds 100 mm, the card passing property and the like deteriorate, and defects in product processing may occur. It is more preferable that the fiber length is in the range of 20 to 70 mm from the viewpoint of improving the card passing property at the time of product processing and the formation of the nonwoven fabric.

  In the present invention, the single fiber fineness of the biodegradable fiber A is preferably 50 dtex or less in view of the influence of the number of contacts on the strength characteristics when the fiber cushion material is made using the biodegradable fiber, and the base fiber In consideration of blendability with B and high-order workability, it is more preferably 10 dtex or less. Further, if the single fiber fineness of the biodegradable fiber A is less than 0.5 dtex, the contact itself after melting becomes small, so that the target rigidity is inferior, which is not preferable, and from the aspect of obtaining sufficient rigidity of the contact It is preferably 2 dtex or more.

  In view of the influence on the rigidity of the fiber cushion material, the single fiber fineness of the biodegradable fiber B is preferably 10 dtex to 50 dtex, and 10 dtex to 20 dtex is preferable in consideration of the blendability with the biodegradable fiber A and high-order processability. More preferred.

  In the fiber structure constituting the fiber cushion material of the present invention, at least a part of the intersection of the biodegradable fiber A and the component fiber contacting with the biodegradable fiber A is fused, and the component fiber is in the thickness direction of the fiber structure. Oriented. A fiber cushion material having cushioning properties can be obtained by fusing at least a part of the intersection between the biodegradable fiber A and the constituent fiber in contact therewith. Normally, the biodegradable fiber A is fused with the other biodegradable fiber A, and is also fused with the biodegradable fiber B.

  When the fiber cushion material bends (bends), one surface of the fiber structure constituting the fiber cushion material extends and the other surface contracts. The fiber cushion material of the present invention is excellent in rigidity because the constituent fibers of the fiber structure constituting the fiber cushion material can be opposed to the pressure from the shrinking surface side by being oriented in the thickness direction. Since the rigidity is excellent, the basis weight can be lowered, and the weight of the fiber cushion material can be reduced.

  The weight ratio between the biodegradable fiber A and the biodegradable fiber B, which are constituent fibers of the fiber structure constituting the fiber cushion material of the present invention, may be selected depending on the application, but is usually based on the total amount of the fiber structure. The biodegradable fiber A is 30 to 70% by weight, and the biodegradable fiber B is 70 to 30% by weight.

  Such a fiber structure is obtained by blending the biodegradable fiber A and the biodegradable fiber B, applying to a card machine, forming a non-woven web, and then zigzag using a pleating machine, a strut machine, or an air lay machine. It can be obtained by applying a heat treatment at a temperature equal to or higher than the melting temperature of the sheath component of the fiber A, and melting and pressure bonding. By using such a fiber structure as a fiber cushion material, such a fiber cushion material exhibits extremely excellent biodegradability, and even if the basis weight is small, it is difficult to bend, that is, it can maintain high rigidity. .

  Hereinafter, the present invention will be described more specifically with reference to examples. Various characteristics used in the present invention can be measured as follows.

(1) Melting temperature of thermoplastic resin The melting temperature of a thermoplastic resin is measured with a differential scanning calorimeter (DSC) under a nitrogen stream at a heating rate of 10 ° C./min. In the present example, a pyris manufactured by Diamond was used as the DSC.

(2) Single fiber fineness The single fiber fineness is measured by the method shown in JIS L-1015 (1999) -8-5-1.

(3) Rigidity of fiber cushion material A sample obtained by cutting a fiber cushion material to be measured into a shape of 150 mm x 50 mm was placed on two support bases arranged at an interval of 100 mm, and then the support base A central portion (a portion 50 mm from the support base) was pressed downward at a pressing speed of 20 mm / min with a pressing wedge. This pressurization state is sensed by a tensile testing machine, and the load at the point where the load becomes maximum (hereinafter, maximum point load) is measured. If this maximum point load is 10 N / 50 mm or more, it can be evaluated that it is excellent in rigidity.

Example 1
Polylactic acid having a melting temperature of 130 ° C. (Nature Works; grade 6300D) as a sheath component and polylactic acid having a melting temperature of 170 ° C. (Nature Works; grade 6201D) as a core component at a spinning temperature of 240 ° C. And then melt melt spun at a take-up speed of 1200 m / min to obtain a core-sheath type composite undrawn yarn having a core-sheath composite ratio of 50:50. Next, the obtained core-sheath composite unstretched yarn was stretched 3 times in warm water at a temperature of 80 ° C. to give a 4.4 dtex stretched yarn. After crimping, an oil was applied by a spray method, The fiber length was cut to 51 mm to obtain a short fiber-shaped biodegradable fiber A.

  Also, polylactic acid (Nature Works, Grade 6201D) having a melting temperature of 170 ° C. is discharged from the spinneret at a spinning temperature of 240 ° C., melt-spun at a take-up speed of 1000 m / min, and unstretched in a single structure form. I got a thread. Next, the obtained undrawn yarn was drawn 3 times in warm water at a temperature of 80 ° C. to obtain a 14.4 dtex drawn yarn. After crimping, an oil was applied by a spray method, and then a fiber length of 51 mm. The biodegradable fiber B having a short fiber shape was obtained.

The obtained biodegradable fiber A 70% by weight and the biodegradable fiber B 30% by weight obtained by opening with a separate spreader are mixed, and the card machine has a thickness of 5 mm and a basis weight of 30 g / m ² . Got a web. This non-woven web is zigzag with a pleating machine at a height of 20 mm, sandwiched between steel plates with a surface temperature of 180 ° C., compressed to a thickness of 10 mm, and heat-treated at a temperature of 150 ° C. for 20 minutes in a hot air dryer. A fiber cushion material (weight per unit area: 600 g / m ² ) was obtained. At least a part of the intersection between the biodegradable fiber A and the constituent fiber in contact with the biodegradable fiber A was fused, and the constituent fiber was oriented in the thickness direction of the fiber structure. Table 1 shows the results of evaluating the basis weight, thickness, and rigidity of the obtained fiber cushion material.

(Comparative Example 1)
70% by weight of the biodegradable fiber A obtained in Example 1 and 30% by weight of the biodegradable fiber B obtained in Example 1 were mixed, and a web having a thickness of 30 mm and a basis weight of 600 g / m ² was obtained using a card machine. None, this web was sandwiched between iron plates having a surface temperature of 150 ° C., compressed to a thickness of 10 mm, and heat treated at a temperature of 150 ° C. for 20 minutes in a hot air dryer to obtain a fiber cushion material. At least a part of the intersection between the biodegradable fiber A and the constituent fiber in contact with the biodegradable fiber A was fused, but the constituent fiber was oriented in the surface direction of the fiber structure. Table 1 shows the results of evaluating the basis weight, thickness, and rigidity of the obtained fiber cushion material.

Claims (2)

It is a core-sheath type composite fiber, and both the sheath part and the core part are composed of a biodegradable thermoplastic resin, and the biodegradable thermoplastic resin constituting the core part is more than the biodegradable thermoplastic resin constituting the sheath part. A biodegradable fiber A having a high melting temperature and a biodegradable thermoplastic resin having a melting temperature at least 20 ° C. higher than the biodegradable thermoplastic resin constituting the sheath of the biodegradable fiber A A fiber cushion material comprising a fiber structure having a degradable fiber B as a main constituent fiber and satisfying the following requirements.
(1) At least a part of the intersection between the biodegradable fiber A and the constituent fiber in contact with the biodegradable fiber A is fused. (2) The constituent fiber is oriented in the thickness direction of the fiber structure.   The fiber according to claim 1, wherein both the biodegradable thermoplastic resin constituting the sheath part and the core part of the biodegradable fiber A and the biodegradable thermoplastic resin constituting the biodegradable fiber B are polylactic acid. Cushion material.