JP2000282329A - Sea-island composite staple fiber - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] To bring the solubility parameter (SP value) of the sea component close to the SP value of the high molecular weight polymer A as the island component, thereby increasing the adhesiveness of the sea-island component and crimping Provided is a sea-island composite staple fiber which is less likely to generate fibrils in a bent portion of the fiber at the time of application, and which is less likely to be peeled and split in the longitudinal direction of the fiber even after card processing and needle punching processing and has good processability. The cross section of the fiber is a sea-island composite fiber comprising polyethylene as a sea component and a high molecular weight polymer as an island component, wherein the sea component has a hydrogenated conjugated diene-based polymer block B and an aromatic polymer. It comprises a vinyl polymer block C, wherein the block C contains a thermoplastic polymer which is a block copolymer occupying 10 to 50% by weight, and the content of the block copolymer in polyethylene which is a sea component is 1%. A sea-island composite staple fiber, characterized in that the content is 50 to 50% by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a polyisocyanate having a hydrogenation ratio of 8 which is compatible with polyethylene which is a sea component of sea-island composite fibers.
By adding a thermoplastic polymer which is a block copolymer composed of a conjugated diene-based polymer block B and an aromatic vinyl polymer block C of 0% or more, the solubility parameter (SP value) of the sea component is reduced to the island component. Approaching the SP value of the high molecular weight polymer, thereby increasing the adhesiveness of the sea-island component, making it difficult for fibrils to be generated in the bent portion of the fiber during crimping, and even after carding and needle punching. The present invention relates to a sea-island type composite staple fiber which has a good process passage property in which the fiber is not easily separated and split in the longitudinal direction.

[0002]

2. Description of the Related Art In the production of ultrafine fibers having a monofilament of 0.1 denier or less, direct spinning tends to cause yarn breakage, so there is a limit in fineness, and a composite spinning means is used. According to the composite spinning method, a joint type (multilayer type or petal type) in which two components are highly divided and arranged in an array, and a sea-island type in which one component is highly dispersed in other components, from the state of the cross section of the fiber. There is. The sea-island type fiber is often used for artificial leather because the fineness of the island component after extracting and removing the sea component can be made smaller than that of the joint type fiber. As a method of manufacturing artificial leather, sea-island type composite staple fiber is made into a non-woven fabric with a card, and it is overlapped and entangled with a needle punch,
After the necessary treatment, a method of extracting and removing sea components is adopted.

[0003] As a method for producing a sea-island type cross section, a method of discharging a polymer of an island component into a polymer of a sea component from a needle pipe in a spinning nozzle to form a sea-island shape, a solubility parameter (SP value) or spinning When two types of polymers having different melt viscosities are mixed, a polymer having a high SP value is rounded due to its surface tension and becomes an island, or a polymer having a high melt viscosity is rounded due to surface tension,
There is a method of forming islands and sea-island fibers. In the case where a sea island is used by utilizing the difference in SP value, polyethylene having a low SP value is often used. As the island component, polyamide (SP value: 13.5) and polyethylene terephthalate (SP value: 10.5) are often used.
There is a difference in SP value from that of polyethylene, and peeling at the adhesive surface is likely to occur.

It is conceivable that the peeling at the bonding surface occurs when a buckling crimp is applied in a drawing step in a step of producing a staple fiber. When a fiber is crimped and bent, distortion occurs at the bent portion and peeling and splitting may occur at the bonding surface between the sea component and the island component. Furthermore, the fiber surface is damaged in the carding and needle punching steps, and peeling and splitting occur in the longitudinal direction of the fiber, resulting in fibrillation. When the fibrillated fibers are entangled, the fibers locally become a high-density NEP, and after dyeing, they tend to become stained spots, resulting in surface defects.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a conjugated diene-based polymer block B having a hydrogenation ratio of 80% or more and an aromatic vinyl resin in polyethylene which is a sea component of the sea-island composite fiber. By including a thermoplastic polymer which is a block copolymer composed of the polymer block C, the solubility parameter (SP value) of the sea component is brought close to the SP value of the high molecular polymer A which is the island component. Increases sea-island adhesiveness, hardly generates fibrils in the bent portion of fiber when crimping is applied, and has good process passability, which is difficult to peel and split in the longitudinal direction of fiber even after card processing and needle punching processing An object is to provide a sea-island type composite staple fiber.

[0006]

That is, the present invention relates to a sea-island composite fiber comprising, in a cross section of a fiber, polyethylene as a sea component and high molecular weight polymer as an island component,
The sea component is composed of a conjugated diene-based polymer block B having a hydrogenation ratio of 80% or more and an aromatic vinyl polymer block C, and the block C is a block copolymer occupying 10 to 50% by weight. The content of the block copolymer in polyethylene which is a sea component and contains a plastic polymer is 1
It is a composite staple fiber characterized by being about 50% by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer used for the sea component in the sea-island composite fiber of the present invention is preferably polyethylene. In general, the sea component can be arbitrarily selected according to the combination of the SP value with the island component and the combination of the melt viscosity, but when it is made into artificial leather, it is extracted and removed. Even low polyethylene is better.

As the thermoplastic polymer to be added to the sea component polyethylene of the present invention, a thermoplastic polymer which is compatible with the polyethylene and has an SP value between polyethylene and a polymer such as polyamide or polyethylene terephthalate is selected. There is a need. Therefore, the following block copolymers having an SP value of 8 to 9 are suitable.

This block copolymer is obtained by hydrogenating a block copolymer consisting of a polymer block C mainly composed of an aromatic vinyl compound and a polymer block B mainly composed of a conjugated diene compound, and is based on a conjugated diene. 80% or more, preferably 90% or more, particularly preferably 95% or more of the aliphatic double bond is a saturated bond.
It is a block copolymer having a number average molecular weight of 30,000 to 300,000. If the hydrogenation rate (hydrogenation rate) is less than 80%, thermal degradation tends to occur during melt spinning, which is not preferable.

As the aromatic vinyl compound constituting the polymer block C, for example, styrene, α-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene,
-Methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4- (phenylbutyl) styrene and the like are most preferred, with styrene being most preferred.

One block of the aromatic vinyl polymer block C has a number average molecular weight of 4,000 to 50,000, especially 5
It is preferable to have a number average molecular weight of 000 to 40,000, and if the molecular weight is less than 4000, the spinnability is inferior. on the other hand,
If the molecular weight exceeds 50,000, the melt viscosity of the block copolymer will be too high, and the thermoplasticity will be impaired, making spinning difficult.

The content of the block C is 10 to 50% by weight,
Preferably it is in the range of 10 to 50% by weight. If the styrene content is less than 10%, moldability and heat resistance will be poor, and the mechanical properties of the target block copolymer will be insufficient. On the other hand, when the content of the block C exceeds 50% by weight, the viscosity becomes extremely high, and the spinning condition deteriorates.

As the block B of the block copolymer used in the present invention, there is a block composed of 13-butadiene, isoprene, pentadiene, hexadiene and the like. In the present invention, isoprene or isoprene-butadiene is used in combination. Is preferred.

The block composed of isoprene is mainly composed of 1,4 bonds or has more 1,2 bonds or 3,4 bonds depending on polymerization conditions and the like. In the present invention, from the viewpoint of heat resistance, an isoprene block having 1,4 bonds of 70% or more is desired.

The form of block B when isoprene-butadiene is used in combination may be any of random, block or tapered.

The number average molecular weight of one of the blocks B is 1
About 0000 to 150,000, especially 15000 to 130
Approximately 000 is preferable, and if it is out of this range, it tends to be inferior in spinnability.

The block form of the block copolymer in the present invention is represented by C (BC) n and (CB) n. Here, C represents a block composed of an aromatic vinyl monomer, B represents a block composed of a conjugated diene monomer, for example, isoprene or a block composed of isoprene-butadiene, and n is an integer of 1 or more. Of these, the form of CBC is most preferably used.

The copolymer comprising block C and block B can be produced by various known methods. For example, the method described in Japanese Patent Publication No. 40-23798 may be used, and the above vinyl aromatic compound and the conjugated diene compound can be synthesized in an inert solvent using a lithium catalyst such as n-butyllithium. It is possible. And as a method of hydrogenating the block copolymer,
It can be carried out by a known method, for example, a method described in JP-B-42-8704, JP-B-43-6636, etc., as long as the hydrogenation rate is 80% or more as described above. It is not particularly limited.

The content of the block copolymer in polyethylene as a sea component is required to be 1 to 50% by weight, preferably 5 to 40% by weight.
If the content is less than 1% by weight, the SP value is too small to approach the island component, and the effect of suppressing sea island separation and splitting is small. On the other hand, when the content is 50% by weight or more, the rubber elasticity of the block copolymer increases, and the spinning property deteriorates.

The high molecular weight polymer which can be used in the sea-island type conjugate fiber of the present invention can be used in combination with the sea component polyethylene in consideration of the balance between the SP value and the melt viscosity, depending on the use and performance. Can be arbitrarily selected. Examples thereof include polyester polymers such as polyethylene terephthalate and polybutylene terephthalate, polyolefin polymers such as polyethylene and polypropylene, polyamide polymers such as nylon 6 and nylon 66, and other polystyrene polymers and polyvinyl Examples thereof include alcohol-based polymers and vinyl alcohol-ethylene copolymers.
Species, or two or more species are used.

The polyethylene terephthalate-based polymer and / or the polybutylene terephthalate-based polymer may contain one or more other dicarboxylic acid components, oxycarboxylic acid components, and other diol components as copolymerized units, if necessary. You may have.

In this case, other dicarboxylic acid components include aromatic dicarboxylic acids such as diphenyldicarboxylic acid and naphthalenedicarboxylic acid or ester-forming derivatives thereof; dimethyl 5-sodium sulfoisophthalate, 5-sodium sulfoisophthalic acid Metal sulfonate group-containing aromatic carboxylic acid derivatives such as bis (2-hydroxyethyl); oxalic acid, adipic acid, sebacic acid,
Aliphatic such as dodecane diacid, dicarboxylic acids or ester-forming derivatives thereof can be mentioned.

Examples of the oxycarboxylic acid component include p-oxybenzoic acid, p-β-oxyethoxybenzoic acid, and ester-forming derivatives thereof.

The diol component includes aliphatic diols such as diethylene glycol, 1,3-propanediol, 1,6-hexanediol and neopentyl glycol;
Examples thereof include 1,4-bis (β-oxyethoxy) benzene, polyethylene glycol, and polybutylene glycol.

The production method for obtaining sea-island composite staple fibers is as follows:
It can be arbitrarily selected according to the required fiber fineness, fiber use, performance, etc.

The single yarn denier of the sea-island composite staple fiber is not particularly limited, and can be arbitrarily selected depending on the application. Also, the cut length can be arbitrarily selected depending on the use.

The sea-island composite staple fiber is used by blending various additives as necessary. For example, a catalyst, a coloring inhibitor, a heat-resistant agent, a flame retardant, a deodorant, an optical brightener, a matting agent, a coloring agent, a gloss improving agent, an antistatic agent, an aromatic, inorganic fine particles, and the like may be included. .

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the following examples, the states of stretching and crimping of sea-island fibers obtained by combining various A high-molecular polymers and various block copolymers, peeling after passing through a card, passing through a needle punch, and splitting are shown.

The method of crimping sea-island fibers, the method of treating cards and needle punches, and the method of evaluating fiber peeling and splitting are as follows.

[Stretching and application of crimp]: After spinning, after stretching under predetermined conditions, the number of crimps is 15 to 20 pieces / inch and the crimp rate is 10 using a mechanical crimping machine of a push-in type. ~ 2
The nip roller pressure and the doctor plate pressure were adjusted to 0% to give buckling crimps. The side state of the fiber was observed with an optical microscope in order to confirm the peeling and splitting of the crimped raw cotton.

[Card treatment] A web was made through a miniature card so as to have a basis weight of 50 g / m ² , and the presence or absence of nep and the side surface state of the fiber after card treatment were observed with an optical microscope.

[Needle punching treatment]; a web having a basis weight of 500 g / m ² was prepared through a card and cross wrapper process, and the needle was punched at 1,000 needles / cm ² , followed by cutting the web. The entangled state of the fibers on the cut surface was observed with a scanning electron microscope, and it was observed whether the fibers were entangled without suffering peeling or damage to split fibers. In addition, if the fibers are damaged and peeled or split during needle-punch confounding, the fibers are less likely to be entangled with each other, causing strong spots on the web. Was observed for any confounding defects.

Example 1 Polyethylene 2 as a sea component
In a weight ratio of 5% and 75% of nylon-6 as an island component, 5% by weight with respect to polyethylene, a block B having a hydrogenation ratio of 85% and a block C having a weight ratio of block C of 30% were used. The polymers were mixed and spun to form a sea-island structure. After spinning, perform stretching,
The crimp was applied by using a press-type mechanical crimping machine. When the side surface of the fiber was observed with an optical microscope after crimping, peeling and splitting were not observed. After cutting to a predetermined length and performing carding and needle punching, the fibers inside the web were observed with a scanning electron microscope, and no splitting of the fibers was observed. Further, each of the webs was immersed in a toluene bath at 90 ° C. for 30 minutes to extract a polyethylene component, which is a sea component of the composite fiber. No adverse effect of the block copolymer contained in the sea component polyethylene component was observed by this extraction,
A web composed of ultrafine fibers of the island component nylon-6 from which the polyethylene component was well extracted and removed was obtained.

Comparative Example 1: Polyethylene 2 as a sea component
In a weight ratio of 5% and 75% of nylon-6 as an island component, the ratio of block B was 85% and the weight ratio of block C was 30% at a ratio of 0.5% by weight with respect to polyethylene. The block copolymer was mixed and spun to form a sea-island structure. After spinning, drawing was performed, and crimping was applied using a press-in type mechanical crimping machine. When the side surface of the fiber was observed with an optical microscope after crimping, peeling and splitting were observed. Further, after cutting to a predetermined length, card processing, and needle punching, the web was cut, and the entangled state of the fibers on the cut surface was observed with a scanning electron microscope.
Splitting was seen. Also, on the surface of the web, a nep portion in which fibrillated fibers by peeling and splitting were intertwined in a complicated manner was observed. This nep portion is not preferable because, for example, when artificial leather is used, it causes stain spots after dyeing.

By varying the combination of the mixing ratio of the block copolymer to polyethylene, the hydrogenation ratio of the block B, and the weight ratio of the block C in the block copolymer, the resulting fiber after crimping was obtained. Tables 1 and 2 show examples and comparative examples of the results of side surface observation, the results of observation of the fiber side surface after card processing, and needle punching.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

According to the present invention, in the sea-island fiber, the sea-island adhesiveness is improved, fibrillation is less likely to occur in the bent portion of the fiber when crimping is applied, and the fiber length is improved even after carding or needle punching. It is possible to provide sea-island composite staple fibers having good processability because they are difficult to peel and split in the direction.

Claims (2)

[Claims] 1. A sea-island composite fiber composed of a polyethylene as a sea component and a high molecular weight polymer as an island component in a cross section of the fiber, wherein the sea component contains a conjugated diene-based fiber having a hydrogenation ratio of 80% or more. A sea-island composite staple fiber comprising a polymer block B and an aromatic vinyl polymer block C, wherein the block C contains a thermoplastic polymer which is a block copolymer occupying 10 to 50% by weight. . 2. The method according to claim 1, wherein the polyethylene is a sea component.
The sea-island composite staple fiber according to claim 1, wherein the content of the block copolymer is 1 to 50% by weight.