JPH03279417A - Heat bonding conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the subject new sheath-core type fiber, having a core component composed of a polyester and a sheath component composed of a specific heat bonding composition, excellent in process passableness in post-processing and heat bonding properties and capable of providing a nonwoven fabric having soft hand with excellent bulk recovery properties. CONSTITUTION:The objective fiber obtained by using a polyester having >=200 deg.C melting point as a fiber-forming component constituting a core component and a component containing (A) >=50wt.% high-density polyethylene having >=0.95g/cm<3> density and 1-50g/10min melt flow rate, (B) 0.3-27wt.% ethylene copolymer prepared by copolymerizing 0.5-40wt.% alkyl (meth)acrylate and 0.3-10wt.% maleic anhydride with ethylene and (C) 0.3-27wt.% linear low-density polyethylene, obtained by copolymerizing an alpha-olefin and having 0.9-0.935g/cm<3> density and 0.3-100g/10min melt flow rate so as to provided 3-40wt.% total amount of the components (B) and (C).

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a core-sheath type heat-adhesive conjugate fiber suitable for obtaining a nonwoven fabric with excellent heat adhesiveness and heat resistance, and good texture and bulk recovery properties. Regarding.

(Prior art) In recent years, there has been a growing demand for nonwoven fabrics for use in filters, food packaging, hygiene products, etc. to be manufactured using thermoadhesive composite fibers, which have excellent adhesive strength, bulk recovery properties, texture, etc. There is a need for thermoadhesive composite fibers suitable for obtaining nonwoven fabrics.

Conventionally, as a core-sheath type heat-adhesive composite fiber, for example, JP-A-53-86836 discloses a polyolefin type fiber using polypropylene as a fiber-forming component (core component) and polyethylene as an adhesive component (sheath component). Composite fibers have been proposed. This composite fiber has excellent adhesive properties because both the core and sheath components are olefin-based polymers and have good affinity. However, due to the chemical structure and properties unique to polyolefin, the resulting nonwoven fabric has no stiffness and has poor bulk recovery properties. It was inferior.

Further, JP-A-57-176217 proposes a composite fiber in which the core component is polyester, and the sheath component is polyethylene or polypropylene. This composite lIN
Although the nonwoven fabric obtained from the above-mentioned nonwoven fabric has excellent bulk recovery properties, it has low adhesive strength due to low affinity between the core component and sheath component, and the polyethylene used has a high density. There was a problem that the texture was hard.

In order to solve this problem, JP-A-1-92415 proposes a method in which modified polyethylene copolymerized with unsaturated carboxylic acid or the like is used as a sheath component. However, since such modified polyethylene has poor heat resistance, it not only has the disadvantage that the fibers tend to turn yellow;
Since the modified polyethylene generally has low crystallinity and is too soft, III easily deforms in thread guide parts such as guides, rollers, clothing, etc., and the contact area between the fibers and thread guide parts becomes large, resulting in significantly increased friction. There were some drawbacks. For this reason, the fiber supply becomes unstable during mechanical push-crimping and application, which tends to cause crimp defects, and it also tends to get wrapped around cards, cylinder rollers, etc. in post-processes such as web creation. There was a problem.

(Objective of the Invention) The object of the present invention is to improve the various drawbacks of the prior art, and to provide a material that has good process passability during post-processing, excellent thermal adhesion, has a soft texture, and has good bulk recovery properties. An object of the present invention is to provide a novel thermoadhesive composite tlAN suitable for obtaining a nonwoven fabric.

(Structure of the Invention) As a result of intensive studies to achieve the above object, the present inventors have found that thermal adhesion is improved when high-density polyethylene and polyethylene copolymerized with unsaturated carboxylic acid are used together as adhesive components. Knew.

However, with this nonwoven fabric, the nonwoven fabric still had a soft texture, fRM<, and its passability through the post-processing process was insufficient. As a result of further intensive study, it was discovered that, surprisingly, the above objects could be simultaneously achieved by blending a specific copolymerized polyethylene and linear low-density polyethylene with high-density polyethylene, leading to the present invention.

That is, according to the present invention, in the core-sheath type heat-adhesive composite Il fiber having 11 fiber-forming components as a core component and a heat-adhesive component as a sheath component, the core component is mainly made of polyester having a melting point of 200° C. or higher. Become,
The sheath component includes at least (A) high-density polyethylene with a density of 0.959/ci or more and a melt flow rate of 1 to 509/10 min = 50% by weight or more (B) alkyl (meth)acrylate 0.5 to 40% by weight; Copolymerized polyethylene copolymerized with 0.3 to 10% by weight of maleic anhydride = 0.3 to 271! Amount % (C) α
- Density of copolymerized olefin: 0.9 to 0.9359
/cat, melt flow rate 0.3~100g/
10-minute linear low-density polyethylene: 0.3 to 27% by weight [however, the total amount of component B and component C is 3 to 40% by weight] A thermoadhesive composite fiber characterized by being made of a composition containing: is provided.

In the present invention, the heat-adhesive component used for the sheath component of the heat-adhesive composite IIN has a normal heat-adhesive processing temperature of 150 to
Since the temperature is 180°C, it is preferable that its softening point is 150°C, and a polyethylene polymer is used because it is easy to obtain a nonwoven fabric that has excellent heat and humidity resistance and has a soft texture.

High density polyethylene (hereinafter referred to as HDPE) used in the present invention
) has a density (d) of 0.959/ca1 or more and a melt flow rate (hereinafter sometimes referred to as VFR) of 1 as measured by JIS K6730 method.
It needs to be ~50g/10 minutes.

If the density is less than 0.959/d, the crystallinity will be insufficient and the cohesive force will decrease, resulting in a decrease in adhesive strength, which is not preferable. Furthermore, if the VFR is less than 1 g/10 minutes, the fluidity during melt spinning will decrease, so if the spinning speed is not extremely reduced, a composite imei will not be obtained.

On the other hand, when the VFR exceeds 50 g/10 minutes, the molecular weight becomes too small and the adhesive strength decreases, which is not preferable.

Copolymerized polyethylene (hereinafter referred to as C0PE) used in the present invention
) is a polyethylene obtained by copolymerizing maleic anhydride or a derivative thereof and an alkyl (meth)acrylate as a copolymerization component, and is usually produced by a pressure radical polymerization method.

Among these copolymerization components, maleic anhydride or a derivative thereof has a good affinity with the polyester core component, so it strengthens the adhesion between the core component and the sheath component and improves the strength of the nonwoven fabric. However, if too much is copolymerized, it is difficult to obtain further effects, and it is also disadvantageous in terms of cost and manufacturing difficulties, so the amount of copolymerization is 0.3 to 10.
It is necessary to make it weight-%.

Alkyl (meth)acrylate, another copolymerization component, is effective in softening the texture of nonwoven fabrics.
It also has the effect of imparting elasticity to the resin and increasing its impact breaking force. However, if the amount of copolymerization becomes too large, the polymer becomes too flexible and its compatibility with HDPE etc. decreases, causing C0PE to form on the fiber surface.
As a result, the friction between the fibers and various thread guides becomes large, and the above-mentioned disadvantages occur frequently. Therefore, the copolymerization amount needs to be 0.5 to 40% by weight.

In addition, as the alkyl (meth)acrylate suitably used, for example, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, lobethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2- Hydroxyethyl (
Examples include ester compounds of acrylic acid or methacrylic acid such as meth)acrylate.

In addition, there is no need to specifically limit the VFR of C0PE, but
If it is too small, it may become difficult to spin depending on the amount used, while if it is too large, it will be difficult to handle and depending on the amount used, the adhesiveness may also be reduced. It is desirable to select and use the appropriate one.

Linear low-density polyethylene (hereinafter sometimes referred to as L-LDPE), which is another component used in the sheath component of the present invention, usually contains an α-olefin having 4 to 12 carbon atoms as a copolymerization component, and the presence of a catalyst. The above can be obtained by coordinating anionic polymerization under low pressure in the same way as conventional high-density polyethylene is produced.The present inventors found that when this L-LDPE is blended, the HDPE and C0PE
It is presumed that this is because C0PE is more finely dispersed due to increased compatibility with C0PE, but it has been discovered for the first time that a composite fiber with high adhesiveness can be obtained.

The copolymerization amount of α-olefin is determined when the density of L-LDPE is 0.
It is not particularly limited as long as it is in the range of 900 to 0.9359/7, but it is usually used in the range of 1 to 15% by weight.

In the present invention, the density of this L-LDPE is 0.90
In the case of 0 g/oi without vortex, the linearity of L-LDPE decreases and the compatibility with HDPE decreases, and as a result, the above-mentioned fine dispersibility of C0PE is not improved, but the adhesive property decreases. On the other hand, when it exceeds 0.935 g/d, the properties of L-LDPE become close to those of HDPE, so the affinity with C0PE decreases and C0P
The fine dispersibility of E is not improved, and as a result, the adhesion is reduced. Moreover, the texture of the nonwoven fabric may become too hard. Therefore, it is important to keep the density of L-LDPE within the above range.

In addition, the MFR of L-LDPE is 0.3 to 1009/10
If it is outside this range, the spinnability deteriorates and stable spinning becomes impossible, or the adhesive strength of the resulting nonwoven fabric decreases, which is not preferable.

Note that L-LDPE may be further copolymerized with an unsaturated carboxylic acid or a derivative thereof, and in this case, the effect of further improving the adhesive strength is exhibited, which is particularly preferable. Preferably used copolymerization components include acrylic acid,
Methacrylic acid, maleic acid, fumaric acid, itaconic acid,
Hymic acid.

Crotonic acid, citraconic acid, etc. and their esters,
*Can list anhydrous substances.

Next, the blending amounts of the various polyethylenes mentioned above are A: HDP
E-50% by weight or more B: C0PE-0.3-27% by weight C: L-LD
PE-0.3 to 27% by weight is required. HDPE
If the amount is 50% by weight, it is not preferable because the crystallinity of the sheath component decreases too much, resulting in a decrease in adhesive strength, and the sheath component becomes too flexible, resulting in a decrease in passability through post-processing steps. Furthermore, if the amount of C0PE and L-LDPE is 0.3% by weight each without swirling, the above-mentioned effects will not be expressed, which is undesirable. On the other hand, if the amount exceeds 30% by weight, the sheath component will become soft. It is not preferable because it becomes too much and the passability of the post-processing process decreases.

In the present invention, the total amount of C0PE and L-LDPE must be approximately 3 to 40% by weight, preferably 3 to 30% by weight. If this is 3% by weight unvortexed, HDP
There is no difference from the case where E alone is used, and the texture of the nonwoven fabric becomes hard and the adhesive strength becomes insufficient. On the contrary, 40 weights-
If it exceeds %, the fiber becomes too flexible and the friction between the fiber and the thread guide increases, resulting in poor passability through a push crimper, card passability, etc.

Further, the blending ratio of C0PE and L-LDPE does not need to be particularly limited as long as the above requirements are satisfied, but preferably the ratio of C0PE/L-LDPE is 1/9 to 9/1, especially 2.
It is desirable to set it to /8 - 8/2.

In the present invention, the composition containing the various polyethylenes described above is used as the sheath component, but any method can be used for mixing the composition.

For example, three types of polyethylene may be melt-mixed at the same time, or two types may be mixed in advance and then the remaining one type may be mixed. In particular, a method of melt-mixing C0PE and L-LDPE and then melt-mixing them with HDPE is preferred because LOPE can be easily uniformly and finely dispersed.

In addition, in the present invention, other polymers may be blended as long as they do not impair the purpose of the present invention, and in particular, when a low melting point polyester is blended, the adhesive strength tends to be improved. However, if too much is added, the spinnability and adhesion strength tend to decrease as well, so the amount added is usually 35% by weight or less.

Further, it is important that the softening point of the low melting point polyester is 150° C. or lower so as not to reduce the heat bonding processability. As such a low melting point polyester, conventionally known copolyester polyesters can be used as they are. Among them,
As acid components, terephthalic acid, isophthalic acid, phthalic acid,
Ethylene glycol contains adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, etc. as a glycol component.

Copolyesters using propylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexane dimetatool, polyoxyalkylene glycol, etc. are preferred from the viewpoint of cost reduction.

Next, the polyester used as the core component of the thermally bonded conjugate fiber of the present invention needs to have a melting point of 200° C. or higher. When the melting point is less than 200°C, when producing a nonwoven fabric using this composite fiber, heat adhesion treatment (usually 150 to 180
It is not good because it cannot withstand temperatures (°C) and only gives a hard texture.

As such polyesters, polyethylene terephthalate, polybutylene terephthalate, and polyesters obtained by copolymerizing these polyesters with a third component are preferably selected because of their good bulk recovery properties, low shrinkage during thermal bonding, and low cost. It will be done. Preferably used copolymerization components include aromatic and aliphatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, adipic acid, and sebacic acid, and lower alkyl esters thereof. Acid components such as hydroxybenzoic acid, ω-hydroxycarboxylic acid, etc.
oxycarboxylic acid, diethylene glycol, neopentyl glycol, cyclohexane-1,4-dimetatool,
Examples include glycols such as 1.6-hexanediol, propylene glycol, and trimethylene glycol, dihydroxy compounds such as polyalkylene glycol, hishydroxyphenylpropane, and bishydroxyphenylsulfone, and two or more of these can be used in combination. You may do so.

Further, as long as the resulting polyester is substantially linear, it is acceptable even if it is a copolymer of a polyfunctional component such as glycerin, petaneerythritol, trimellitic acid, trimesic acid, or pyromellitic acid.

Although the core component of the composite fiber of the present invention is mainly composed of the above-mentioned polyester, other types of polymers may be blended as long as the object of the present invention is not impaired. Usually, the amount is 35% by weight or less, and if it exceeds this amount, the bulk recovery properties of the resulting nonwoven fabric are likely to decrease, and the spinning condition during spinning of composite m-miscellaneous material tends to deteriorate.

The polymer to be mixed is not particularly limited as long as it can be melt-mixed with polyester and can produce composite fibers, but it should have good compatibility with polyester, improve spinning condition, and have good affinity with the sheath component. Polyolefins copolymerized with unsaturated carboxylic acid components (modified polyolefins) are preferably used because they are good and have improved adhesive strength. Note that the modified polyolefins mentioned here include α-olefins such as ethylene propylene plan-1 and pentane-1, acrylic acid, and methacrylic I! , maleic acid,
fumaric acid, itaconic acid, hymic acid.

At least one of unsaturated carboxylic acids such as crotonic acid and citraconic acid, their esters, and tl anhydrides
It also includes a copolymer with a different copolymer component, or a graft copolymer in which at least one of the above copolymer components is grafted onto a polyolefin.

In the present invention, the main target is a core-sheath type composite fiber in which the above-mentioned core component and sheath component are combined in a core-sheath type, but it also includes an eccentric core-sheath type. The ratio of the core component (fiber-forming component) to the sheath component (adhesive component) is preferably 25-65/75-35 (weight ratio). When the core component increases, the adhesive component decreases, and the adhesive strength of the nonwoven fabric tends to decrease. Conversely, when the sheath component increases, the fiber-forming component decreases, and the bulk recovery properties of the nonwoven fabric tend to decrease.

In order to obtain the thermoadhesive fiber of the present invention, a fiber-forming component and an adhesive component may be composite-spun using a conventionally known composite spinneret.

(Effects of the Invention) As mentioned above, the heat-adhesive composite fiber of the present invention has a specific polyethylene blended as an adhesive component, so it has excellent heat-adhesive properties and a very soft texture. It has the characteristic that it can be obtained stably. Furthermore, since polyester is used as the core component, it also has excellent bulk recovery properties.

Therefore, disposable diapers, which have been widely used in the past,
Not only is it suitable for sanitary materials such as sanitary napkins, but
Since it is possible to reduce the basis weight of the nonwoven fabric, it also has the advantage of reducing costs in these fields.

(Example) The present invention will be explained in more detail below with reference to Examples.

In addition, evaluation of winter clothes was performed by the following method.

(1) Heat-adhesive short fibers with a cut length of 51 am are passed through a carding machine to form a web with a basis weight of 309/m, and then heated at 140°C for 20 minutes.
A nonwoven fabric (approximately 5 shoes thick) is prepared by heat treatment for seconds. Five panelists judged the obtained nonwoven fabric by touch.

O: Everyone judged it to be particularly good O: All people judged it to be good Δ: 3 to 4 people judged it to be good A test piece was cut out and measured at a gripping interval of 10α and an elongation rate of 201/min.

The adhesive strength was determined by dividing the tensile breaking force by the heavy chain of the test piece.

(3) Bulk recovery properties: On the nonwoven fabric whose thickness (a) was measured in advance,
An impactor with a diameter of 51 weights and 11 squares covered with a flat rubber with a hardness of 601-1s by the IS K6301 A method was struck at a rate of 195 times per minute from a height of 203 cm.
Dropped 000 times, left for 5 minutes, thickness (bag)
was measured and calculated using the following formula.

Bulk recovery rate (%) = b / a x 100 This value is 9
5% or more is excellent (represented by ◎), 90-95% is good (represented by O), 70-90% is acceptable (represented by Δ), less than 70% is unacceptable (Represented by ×).

G4) Using a ruler card under 25℃ x 65%RH condition with card winding
09. When a web with a basis weight of /d was spun at 30 m/min,
Good (○) indicates that the card could be operated normally, defective (x) indicates that the card could not be operated due to frequent wrapping of the card clothing, and medium fit (Δ) indicates that the card could be operated properly. I judged it.

Examples Polyester listed in Table 1 mainly consisting of polyethylene terephthalate (PET: melting point 260°C) with an intrinsic viscosity of 0.64 was used as the core component, and high-density polyethylene, copolymerized polyethylene, and straight line listed in Table 1 were used as the sheath component. Using low-density polyethylene, it was extruded from a core-sheath type composite spinneret with a pore diameter of 0.5 φ and a number of holes of 260, and the spinning speed was 8007FL.
I turned it over in / minute. The core component melting temperature at this time is 280℃
, Sheath component dissolution I! The temperature was 250°C, and the core/sheath composite ratio was 5.
0150 (weight ratio).

The obtained undrawn fibers were bundled into a tow, and the drawing temperature was 7.
After stretching at 0°C and a stretching ratio of 2.5 times, and applying 15 crimps/25 crimps using a staff 7-box,
A relaxation heat treatment was performed for 0 minutes, and the fiber was cut into a fiber length of 51 am+ to obtain a heat-adhesive composite fiber. All of the short fibers obtained were 2 denier.

This fiber was made into a web with a basis weight of 309/Td by the method described above, and then heat-treated to make a nonwoven fabric. The results are summarized in Table 1.

The polymers used in the table are as follows.

A: Mitsubishi Modic L-400F manufactured by Mitsubishi Yuka Co., Ltd. (maleic acid copolymerized low density polyethylene: softening point 116°C) B-1 = 10% metal methacrylate, 3% maleic anhydride copolymerized polyethylene B -2: 50% by weight of methyl methacrylate, 10% by weight of maleic anhydride copolymerized polyethylene B-3: 1% by weight of methyl methacrylate, mylene anhydride I! 10% by weight copolymerized polyethylene B-4 = 35% by weight methyl methacrylate, 8% by weight maleic anhydride copolymerized polyethylene B-5 = 0.3% by weight methyl methacrylate, 0.211% maleic anhydride copolymerized polyethylene B-6 = 10% by weight of methyl methacrylate, 3% by weight of maleic anhydride copolymerized polyethylene C: The acid component consists of 80 mol% of terephthalic acid component and 20 mol% of isophthalic acid component, and the glycol component is hexamethylene glycol component. 90 mol%.

Copolyester consisting of 10 mol% ethylene glycol component (melting point 106°C)

Claims (1)

[Scope of Claims] In a core-sheath type heat-adhesive conjugate fiber having a fiber-forming component as a core component and a heat-adhesive component as a sheath component, the core component is mainly made of polyester with a melting point of 200° C. or higher, and the sheath component is is at least (A) high-density polyethylene with a density of 0.95 g/cm^3 or more and a melt flow rate of 1 to 50 g/10 min: 50% by weight or more (B) alkyl (meth)acrylate 0.5 to 40% by weight, Copolymerized polyethylene copolymerized with maleic anhydride 0.3 to 10% by weight: 0.3 to 27% by weight (C) Density 0.9 to 0.9 copolymerized with α-olefin
35g/cm^3, melt flow rate 0.3-100
g/10 min linear low density polyethylene: 0.3-27
% by weight [However, the total amount of component B and component C is 3 to 40% by weight].