JP5340706B2 - Composite fiber with damping function - Google Patents

Description

  The present invention relates to a fiber excellent in vibration damping performance.

  In recent years, with the change of lifestyle, the demand for quietness has attracted attention, and a better damping material has become necessary. As a fiber material, various uses such as walls, flooring materials and carpet flooring are expected. However, as described in Japanese Patent Publication No. 55-42175, the conventional fiber material is one in which synthetic fibers are arranged in the length and width directions and overlapped to define the arrangement ratio thereof, or Although there are some which can be expected as a damping material such as a non-stretched polyethylene terephthalate fiber as in 1999958 and then heat-shrinked into a dense structure, the constituent fiber itself has damping performance. Because it was not a thing, the effect was not enough. A material such as rubber can be considered as the material itself having damping performance, but even if this is spun in the same way as conventional synthetic fibers, the fibers are stuck together and it is virtually impossible to spin alone. Met. On the other hand, a latent crimpable fiber is known in which a heterogeneous polymer having a shrinkage characteristic is imparted to a synthetic fiber to give a bulkiness and stretchability, for example, a structure having a metal salt sulfonate group A polyester-based composite with excellent stretchability, in which ethylene terephthalate-based copolyester with several mol% units copolymerized and polyethylene terephthalate are eccentrically joined, and a three-dimensional crimp of 50 pieces / 25 mm or more is developed by heat treatment. Fibers have been proposed in Japanese Patent Application Laid-Open Nos. 62-78214 and 1-61511. However, the present situation is that a highly practical synthetic fiber having both vibration damping performance and expansion / contraction performance has not been developed yet.

  Accordingly, the present inventors have intensively studied the fiber material itself having excellent vibration damping performance but also having good latent crimping ability as a fiber. As a result, the specific styrene-isoprene block copolymer has been obtained. (X) is one component, and it has wet heat adhesiveness but is not hot water soluble resin (Y) as another component, specifies the relationship between both melt viscosities, and wet heat adhesiveness at the fiber circumference is Fibers with specified occupancy ratio of resin (Y) that is not hot-water soluble (hereinafter sometimes referred to as wet heat adhesive resin (Y)) have excellent damping performance near room temperature And the present invention has been found.

  That is, the present invention relates to a composite fiber in which two thermoplastic polymers form a parallel or core-sheath structure, and one thermoplastic polymer is a block (A) having a number average molecular weight of 2500 to 40000 comprising a vinyl aromatic monomer. And isoprene or isoprene-butadiene mixture having a number average molecular weight of 10,000 to 200,000, a 3,4 bond and 1,2 bond content of 40% or more, and a block having a main dispersion peak of tan δ at 0 ° C. or higher (B ) Is composed of a block copolymer (X) having a number average molecular weight of 30,000 to 300,000, and the other is composed of a resin (Y) that has wet heat adhesiveness but is not hot water soluble. The weight ratio of the polymer (X) to the resin (Y) that has wet heat adhesiveness but is not hot water soluble is 80/20 to 20/80. Besides perimeter more than 50% wet heat bonding of the fiber cross section has a fiber characterized by comprising arranged such that the resin (Y) is not a hot water solubility.

  More preferably, the resin (Y) that has wet heat adhesiveness but is not hot water soluble is an ethylene-vinyl alcohol polymer, and the ethylene unit content of the polymer exceeds 15%. .

  Furthermore, this invention is a fiber structure containing the composite fiber described above.

  A non-woven fabric structure can be easily obtained from the conjugate fiber of the present invention by a wet heat bonding method.

  Furthermore, the fiber structure containing the conjugate fiber of the present invention can exhibit vibration damping properties and sound absorbing properties.

The present invention is described in detail below.
Block (A) of the block copolymer used as one component of the composite fiber of the present invention is a vinyl aromatic monomer such as styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 3-methylstyrene. , 4-propyl styrene, 4-cyclohexyl styrene, 4-dodecyl styrene, 2-ethyl-4 benzyl styrene, 4- (phenylbutyl) styrene, and the like. It is. The number average molecular weight of the vinyl aromatic block (A) is in the range of 2500 to 40000, but if the molecular weight is less than 2500, the vibration damping performance of the block copolymer is lowered, and if the molecular weight exceeds 40000, the block copolymer The melt viscosity becomes too high and the spinning condition becomes worse. Preferably, it is the range of 3000-38000. Moreover, the thing in the range of 5 weight%-50 weight% is preferably used for the ratio in the block copolymer (X) of a vinyl aromatic block (A). If this proportion is less than 5% by weight, the mechanical properties of the block copolymer will be insufficient. Conversely, if the proportion exceeds 50% by weight, the viscosity will be so high that the spinning condition will be worsened and winding will be impossible. Even if it is wound, it is not preferable because the vibration damping performance is lowered.

  Further, the block (B) of the block copolymer is preferably composed of a monomer using isoprene or isoprene-butadiene in combination. When a monomer other than this is used, for example, in the case of butadiene alone, the temperature at which the damping performance is exhibited is less than 0 ° C. even if the 1,2 bond content is increased, and the function at the temperature actually used is It cannot be obtained and has little practical significance. On the other hand, in the case of isoprene, by setting the 3,4 bond and 1,2 bond contents of the present invention (hereinafter collectively referred to as vinyl bond content) to a specific amount, the temperature is generally 0 ° C. It is possible to exhibit vibration damping performance in a practical temperature range from about 50 to about 50 ° C., which is extremely useful in practice. When isoprene-butadiene is used in combination, if the proportion of isoprene is 40% or more, damping performance is exhibited at 0 ° C. or higher. When used in combination, the form of the block (B) may be random, block or tapered. As the block copolymer block (B), a block copolymer having a total of 3,4 bond content and 1,2 bond content of 40% or more (100% may be used) is used. When the vinyl bond content is less than 40%, sufficient vibration damping performance cannot be obtained in the normal operating temperature range, which is not preferable. Further, the temperature of the main dispersion peak of tan δ (loss tangent) obtained by measuring the viscoelasticity of the block copolymer (X) needs to be 0 ° C. or higher. Even when there is a peak only at a temperature lower than 0 ° C., sufficient damping performance cannot be obtained in the normal temperature range. The number average molecular weight of the block (B) is in the range of 10,000 to 200,000. If the molecular weight is smaller than the above range, the elastic properties are impaired, which is not preferable. On the other hand, if it is too large, the block copolymer (X) has a high melt viscosity, which causes spinning failure. Preferably, it is the range of 15000-195000.

In the present invention, the number average molecular weight of the block copolymer (X) needs to be in the range of 30,000 to 300,000. If the molecular weight is less than 30000, the mechanical properties such as strength and elongation of the core component itself are deteriorated, and the properties of the fiber itself are deteriorated. On the other hand, if it exceeds 300,000, the viscosity increases, spinning becomes unsatisfactory, and the performance also decreases. Preferably the range of 80000-250,000 is good. The block form of the block copolymer (X) is represented by A (BA) _n and (AB) _n . Here, A represents a block composed of an aromatic vinyl monomer, B represents a block composed of isoprene or isoprene-butadiene, and n is an integer of 1 or more. Among these, the thing of the form of ABA is used most preferably.

  Such a block copolymer (X) can be produced by various known methods. For example, (a) a method of sequentially polymerizing an aromatic vinyl compound, isoprene or isoprene-butadiene using an alkyllithium compound as an initiator, (b) an aromatic vinyl compound and then isoprene or isoprene-butadiene are polymerized, Examples thereof include a method of coupling this with a coupling agent, or (c) a method of sequentially polymerizing isoprene or isoprene-butadiene and then an aromatic vinyl compound using a dilithium compound as an initiator. Examples of the alkyl lithium compound include alkyl compounds having 1 to 10 carbon atoms in the alkyl residue, and methyl lithium, ethyl lithium, pentyl lithium, and butyl lithium are particularly preferable. As the coupling agent, dichloromethane, dibromomethane, dichloroethane, dibromoethane, dibromobenzene and the like are used. Examples of the dilithium compound include naphthalenedilithium and dilithiohexylbenzene. The amount used is determined by the required molecular weight, but is generally 0.01 to 0.2 parts by weight of the initiator and 0.04 to 0.8 parts by weight of the coupling agent with respect to 100 parts by weight of the total monomers used for the polymerization. Used in the range of about parts.

  In order to have a vinyl bond content of 40% or more as a microstructure of the isoprene or isoprene-butadiene portion and a peak of the main dispersion of tan δ at 0 ° C. or more, it is necessary to co-polymerize isoprene or isoprene-butadiene during polymerization. A Lewis base is used as the catalyst. Examples of Lewis bases include ethers such as dimethyl ether, diethyl ether and tetrahydrofuran, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, triethylamine, N, N, N ′, N′-tetramethylethylenediamine, and N-methylmorpholine. And amine compounds such as The amount of these Lewis bases used is in the range of about 0.1 to 1000 times the number of moles of lithium in the polymerization catalyst. In the polymerization, a solvent is preferably used for easy control. As the solvent, an organic solvent inert to the polymerization catalyst is used. In particular, aliphatic, alicyclic and aromatic hydrocarbons having 6 to 12 carbon atoms are preferably used. Examples thereof include hexane, heptane, cyclohexane, methylcyclohexane, benzene and the like. In any polymerization method, the polymerization is carried out at a temperature range of 0 to 80 ° C. for 0.5 to 50 hours.

By subjecting the obtained block copolymer to a hydrogenation reaction as necessary, a part or all of the carbon-carbon double bonds in the block made of isoprene or isoprene-butadiene are hydrogenated. For the hydrogenation reaction, a method in which hydrogen in a molecular state is reacted with a known hydrogenation catalyst in a state dissolved in a solvent inert to the reaction and the catalyst is preferably used. The catalyst used is a heterogeneous catalyst such as Raney nickel or a metal such as Pt, Pd, Ru, Rh, Ni supported on carbon, alumina, diatomaceous earth or the like, or a transition metal and an alkylaluminum compound. Ziegler-based catalysts composed of combinations of alkyllithium compounds and the like are used. The reaction is carried out at a hydrogen pressure of normal pressure to 200 kg / cm ² , a reaction temperature of room temperature to 250 ° C., and a reaction time of 0.1 to 100 hours. After the reaction, the block copolymer is solidified with methanol or the like and then heated or dried under reduced pressure, or the reaction solution is poured into boiling water and the solvent is removed azeotropically, and then heated or dried under reduced pressure. Is obtained. The hydrogenation rate is determined by the level of physical properties required, but when importance is attached to heat resistance and weather resistance, it is preferable to hydrogenate to 50% or more, preferably 70% or more.

Resin (Y) having wet heat adhesiveness but not hot water solubility is boiled in boiling water at 100 ° C. for 10 minutes, 90% or more of the weight before dissolution is maintained as a solid phase, and high temperature steam It is sufficient that the adhesive function can be expressed by flowing or easily deforming at a temperature that can be easily realized by the above. Specifically, a thermoplastic resin that can be softened with hot water (for example, about 80 to 150 ° C., particularly about 95 to 100 ° C.) and can be self-adhered or bonded to other fibers, such as a cellulose resin (C _1-3). Alkyl cellulose ether, hydroxy C _1-3 alkyl cellulose ether, carboxy C _1-3 alkyl cellulose ether or a salt thereof), polyvinyl resin (polyvinyl pyrrolidone, polyvinyl ether, vinyl alcohol polymer (ethylene-vinyl alcohol copolymer) Etc.), polyvinyl acetal, etc.), acrylic copolymers and their alkali metal salts, modified vinyl copolymers, polymers with hydrophilic substituents introduced (polyesters with introduced sulfonic acid groups, carboxyl groups, hydroxyl groups, etc.) , Polyamide, polystyrene or salt thereof) Aliphatic polyester resin, such as polylactic acid-based resin. Further, among the polyolefin-based resins, polyester-based resins, polyamide-based resins, polyurethane-based resins, thermoplastic elastomers, and the like, resins that can be softened at a temperature of hot water (high-temperature steam) to develop an adhesive function are also included. These resins can be used alone or in combination of two or more. Among these, an ethylene-vinyl alcohol copolymer is particularly desirable in the configuration of the present invention.

  In the ethylene-vinyl alcohol copolymer, the ethylene unit content (copolymerization ratio) is, for example, more than 15 mol% and 60 mol% or less, preferably 20 to 55 mol%, more preferably 30 to 30 mol%. It is about 50 mol%. When the ethylene unit is in this range, a unique property of having wet heat adhesiveness but not hot water solubility is obtained in a wider range of hot water temperatures. If the proportion of the ethylene unit is too small, the ethylene-vinyl alcohol copolymer easily swells or gels with low-temperature steam (water), and its form is easily changed only once wetted with water. On the other hand, when the proportion of ethylene units is too large, the hygroscopicity is lowered, and it becomes difficult to develop fiber fusion due to heat absorption, so it is difficult to ensure practical strength. When the ratio of the ethylene unit is particularly in the range of 30 to 50 mol%, the processability to a sheet or plate is particularly excellent.

  The saponification degree of the vinyl alcohol unit in the ethylene-vinyl alcohol copolymer is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably 96 to 99.97 mol%. Degree. When the degree of saponification is too small, the thermal stability is lowered, and the stability is lowered by thermal decomposition or gelation. On the other hand, if the degree of saponification is too large, it is difficult to produce the fiber itself.

  Although the viscosity average degree of polymerization of an ethylene-vinyl alcohol-type copolymer can be selected as needed, it is 200-2500, for example, Preferably it is 300-2000, More preferably, it is about 400-1500. When the degree of polymerization is within this range, the balance between spinnability and wet heat adhesion is excellent.

  The weight ratio of the block copolymer (X) and the wet heat adhesive resin (Y) during the production of the composite fiber of the present invention is preferably 8/2 to 2/8. Outside this range, the process properties such as spinning and drawing of the composite fiber are likely to deteriorate, and it may be difficult to achieve desired performance. Therefore, 7/3 to 3/7 is more preferable. Furthermore, in the present invention, it is necessary that 50% or more, preferably 55% or more of the circumference of the fiber is occupied by the wet heat adhesive resin (Y). If it is less than 50%, the agglutination of fibers in the fiberization becomes remarkable, which is not preferable. Such control greatly depends on the weight ratio of both components and the difference in melt viscosity, and the cross section must be carefully designed.

  Further, if necessary, a silicone-based oil agent is applied to the spinning oil to coat the block copolymer, or inorganic fine particles such as ceramics and metal oxides are added to the block copolymer. Spinning may be performed by forming fine irregularities on the surface and reducing the contact portion between the polymers between the fibers.

  At the time of producing the conjugate fiber of the present invention, a conventionally known side-by-side type or core-sheath type conjugate fiber production apparatus can be used and produced while paying attention to the above points, and the spinning yarn is drawn, It can be manufactured by heat setting, and can be applied to the production method of both long and short fibers. Further, the core-sheath type composite fiber may be concentric or eccentric. Further, the cross section may be various atypical cross sections other than circular, or may be a cross section designed so that the block copolymers exposed on the fiber surface do not stick together.

  The suitable fineness of the fiber used for this invention can be arbitrarily determined in the range of 0.4 dtex-50 dtex by a use. Preferably, it is 0.7 dtex-40 dtex.

  Further, the composite fiber of the present invention may contain various additives as required. For example, metal powder, metal oxides such as silica, alumina and titanium oxide, inorganic particles such as calcium carbonate and barium sulfate. And antioxidants, ultraviolet absorbers, flame retardants, crosslinking agents, heat-resistant agents, fluorescent brighteners, colorants, antibacterial agents, fragrances and the like.

  Various applications can be developed by utilizing the vibration-damping properties and sound-absorbing properties of the fibers, and fabrics such as woven fabrics, knitted fabrics, and non-woven fabrics are formed as short fibers and long fibers, and curtains, wall coverings, flooring materials, and ceilings. It is also suitable as an interior interior material such as a material, an interior material such as a vehicle, and a filling product such as hard cotton using the fiber as a filling cotton.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the number average molecular weight is determined by the GPC method, and the molecular structure is identified by measuring the NMR spectrum, and the peak of 4.8 ppm, 5.8 ppm of 3,4 bonds, 1, 2 bonds and 5.3 ppm. From the ratio of 1,4 bond peaks, the content of 3,4 bond and 1,2 bond was calculated, and the tan δ peak temperature was determined by measuring the viscoelastic spectrum with Leo Vibron (Orientic). It was. The number of crimps was measured by the method of JISL-1015-7-12-1.

Reference Example In a pressure-resistant reactor that was dried and replaced with nitrogen, cyclohexane was added as a solvent, n-butyl monomer, isoprene monomer, and styrene monomer were added in this order as a polymerization catalyst for polymerization. The obtained ABA type copolymer was used as a hydrogenation catalyst in cyclohexane to obtain block copolymers (1), (2) and (3) having the molecular characteristics shown in Table 1.

<< Examples 1-3 >>
The polymer (1, 2, 3) obtained in the reference example is disposed as a component in the core component, and an ethylene-vinyl alcohol copolymer having an ethylene content of 44 mol% is disposed as the other component in the sheath component. The weight ratio of both components was combined with block copolymer / ethylene-vinyl alcohol copolymer = 50/50 (spinning temperature 240 ° C., winding speed 800 m / min), and wet-heat stretched according to a conventional method. A core-sheath type composite fiber having a fiber fineness of 5.0 dtex and a fiber length of 51 mm was obtained. Next, 100% of the composite fiber was carded and entangled by hydroentanglement to obtain a nonwoven fabric having a basis weight of about 0.15 kg / m ² . Table 2 shows the results of measuring tan δ at 25 ° C. of the prepared nonwoven fabric and evaluating the vibration damping performance. In Examples 1 to 3, good vibration damping performance was obtained without any problem in processability.

Example 4
Except for changing the weight ratio of both components to block copolymer / ethylene-vinyl alcohol copolymer = 75/25, fiberization was performed in the same manner as in Example 1 to prepare a nonwoven fabric. As a result of evaluating the vibration damping performance of the obtained nonwoven fabric, it was satisfactory.

Example 5
Except for changing the weight ratio of both components to block copolymer / ethylene-vinyl alcohol copolymer = 25/75, fiberization was carried out in the same manner as in Example 1 to produce a nonwoven fabric. As a result of evaluating the vibration damping performance of the obtained nonwoven fabric, it was satisfactory.

Example 6
Except for changing the weight ratio of both components to block copolymer / ethylene-vinyl alcohol copolymer = 50/50 and changing both polymers to side-by-side type, fiberization was performed in the same manner as in Example 1 to produce a nonwoven fabric. did. As a result of evaluating the vibration damping performance of the obtained nonwoven fabric, it was satisfactory.

Example 7
The polymer 1 obtained in the reference example is arranged as a component in the core component, the polylactic acid resin is arranged as the other component in the sheath component, and the weight ratio of both components is determined as block copolymer / polylactic acid resin = 50 / 50 was subjected to composite spinning (spinning temperature 240 ° C., winding speed 800 m / min), and wet-heat drawing was performed according to a conventional method to obtain a core-sheath type composite fiber having a single fiber fineness of 5.0 dtex and a fiber length of 51 mm. Next, the composite fiber 100% was carded and entangled by hydroentanglement to obtain a nonwoven fabric having a basis weight of about 0.15 kg / m ² . Table 2 shows the results of measuring tan δ at 25 ° C. of the prepared nonwoven fabric and evaluating the vibration damping performance. Good vibration control performance was obtained.

<< Comparative Example 1 >>
The same procedure as in Example 1 was performed except that the molecular weight of block A in the block copolymer was changed to 2000. In Comparative Example 1, although there was no problem with fiberization, the vibration damping performance was poor.

<< Comparative Example 2 >>
The same procedure as in Example 1 was performed except that the molecular weight of block A in the block copolymer was changed to 44000. In Comparative Example 2, spinning was not possible due to the high melt viscosity of the block copolymer.

<< Comparative Example 3 >>
The same operation as in Example 1 was carried out except that the molecular weight of block B in the block copolymer was changed to 9000. In Comparative Example 3, fiberization was possible, but the vibration damping performance was poor.

<< Comparative Example 4 >>
The same procedure as in Example 1 was performed except that the molecular weight of block B in the block copolymer was changed to 220,000. In Comparative Example 4, spinning was impossible due to the high melt viscosity of the block copolymer.

<< Comparative Example 5 >>
The same procedure as in Example 1 was performed except that the vinyl bond content of block B in the block copolymer was changed to 35%. Although fiberization was good, only those with poor vibration damping performance were obtained.

<< Comparative Example 6 >>
Except for changing the weight ratio of both components to block copolymer / ethylene-vinyl alcohol copolymer = 85/15, fiberization was attempted in the same manner as in Example 1, but spinning and winding were impossible. Met.

<< Comparative Example 7 >>
Except for changing the weight ratio of both components to block copolymer / ethylene-vinyl alcohol copolymer = 15/85, fiberization was attempted in the same manner as in Example 1, but there were many yarn breaks during spinning, The process was poor.

Claims (2)

In composite fiber two thermoplastic polymers form a core-sheath structure fiber axis direction, a few blocks of average molecular weight 2500-40000 (A) and isoprene or isoprene consisting of one thermoplastic polymer vinylaromatic monomer A block (B) comprising a butadiene mixture, having a number average molecular weight of 10,000 to 200,000, a 3,4 bond and 1,2 bond content of 40% or more, and a peak of tan δ main dispersion at 0 ° C. or more A block copolymer (X) having a number average molecular weight of 30,000 to 300,000, and the other is composed of an ethylene-vinyl alcohol copolymer (Y) having an ethylene unit content exceeding 15 mol%. The weight ratio of the block copolymer (X) to the ethylene-vinyl alcohol copolymer (Y) is 80/20 to 20/8. , And the Note and 100% of the circumferential length of the composite fiber cross-section is an ethylene - composite fiber characterized by being covered by vinyl alcohol copolymer (Y). A fiber structure comprising the conjugate fiber according to claim 1 .