JP2003268631A - Thermobonding sheath-core type conjugate staple fiber and nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermobonding sheath-core type conjugate staple fiber that can give a nonwoven fabric having excellent flame retardancy, mechanical characteristics and soft fabric hand, and provide a nonwoven fabric that contains the stable fiber and has flame retardancy. <P>SOLUTION: In the conjugate staple fiber, a polyester constituting the sheath part has a flow-starting temperature lower than the melting point of a polyester constituting the core part by ≥30°C and the polyester in the sheath part contains 15-45 mol % of isophthalic acid as a copolymerization component. In this case, (1) at least either the polyester of the sheath part or the polyester of the core part contains a phosphorus compound and its content is 2-10 mole % in the conjugate fiber, (2) the content of the phosphorus compound in the core polyester and/or sheath polyester is ≤10 mole %, and (3) the volume ratio of the core part to the sheath part is 35/65-65/35. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite fiber in which a low melting point component is arranged in a sheath portion and a flame retardant component is contained, and the sheath portion is melted by heat treatment to obtain a dry nonwoven fabric or a wet nonwoven fabric. The present invention relates to a heat-adhesive core-sheath type composite staple fiber suitable for, and a staple fiber non-woven fabric containing the fiber and having excellent flame retardancy and mechanical properties.

[0002]

2. Description of the Related Art Synthetic fibers, particularly polyester fibers, are indispensable as clothing and industrial materials because of their excellent dimensional stability, weather resistance, mechanical properties, durability and recyclability. Therefore, polyester fibers are often used also in the field of non-woven fabrics.

In conventional non-woven fabrics made of polyester short fibers, heat-adhesive short fibers are used for heat-bonding the main fibers. Generally, polyethylene terephthalate is used as the core component and isophthalic acid is used as the sheath component. Core-sheath type composite short fibers in which a copolymerized low melting point polymer is arranged are used.

In the non-woven fabric made of such polyester short fibers, a field in which flame retardancy is required (eg furniture material,
When it is used as a wall material, an automobile interior material, etc., flame-retardant processing is necessary, and in order to impart flame-retardant performance in post-processing, the manufacturing process becomes complicated and it is economically disadvantageous.

It is possible to obtain a non-woven fabric having excellent flame retardancy and adhesive properties, which can impart flame retardancy to the resulting non-woven fabric without post-processing, and which is excellent in mechanical properties and soft texture. A core-sheath type composite staple fiber capable of producing the above has not been proposed yet.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a nonwoven fabric excellent in flame retardancy, mechanical properties and soft texture, which cannot be obtained by the prior art. It is intended to provide an adhesive core-sheath type composite staple fiber and a flame-retardant staple fiber nonwoven fabric containing the staple fiber.

[0007]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention is summarized in the following (a) and (b). (A) The flow starting temperature of the polyester forming the sheath is lower than the melting point of the polyester forming the core by 30 ° C. or more,
Polyester in the sheath contains 15 to 45 mol of isophthalic acid.
% Of copolymerized composite fibers, the following (1) to
A heat-adhesive core-sheath type composite short fiber which simultaneously satisfies (3). (1) The polyester of at least one of the core portion and the sheath portion contains a phosphorus compound represented by the following formula (A) and is contained in the composite fiber in an amount of 2 to 10 mol%. (2) The content of the phosphorus compound represented by the following formula (A) in the core polyester and / or the sheath polyester is 10 mol% or less. (3) The volume ratio (core / sheath) of the core and the sheath is 35/65.
65/35.

[Chemical 2] (In the formula, R ¹ and R ³ are hydrocarbon groups having 1 to 18 carbon atoms, R ²
Represents an ester-forming group, and A represents a trivalent organic residue. The compound may be an acid anhydride. ) (B) Includes the heat-bondable core-sheath type composite staple fiber described in (a),
A short-fiber non-woven fabric having a LOI value of 25 or more indicating flame retardancy.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
First, in the heat-adhesive core-sheath type composite short fiber which is the binder fiber of the present invention, the flow starting temperature of the polyester constituting the sheath is 30 ° C. or more lower than the melting point of the polyester constituting the core. When the difference between the flow start temperature of the sheath portion and the melting point of the core portion is less than 30 ° C, the thermal adhesion performance is reduced and the resulting nonwoven fabric has poor mechanical properties such as strength. It should be noted that the flow starting temperature is a flotester (Shimadzu CFT-50).
0 type), the temperature is increased from the initial temperature of 50 ° C. at a rate of 10 ° C./min under conditions of a load of 100 Kgf / _cm ² and a nozzle diameter of 0.5 mm, and the temperature at which the polymer begins to flow out from the die is referred to. .

Isophthalic acid must be copolymerized in the polyester of the sheath portion in an amount of 15 to 45 mol%. When the copolymerization amount of isophthalic acid is less than 15 mol%, the thermal adhesive performance is deteriorated and the strength of the resulting nonwoven fabric is decreased. In addition, the difference between the flow start temperature of the sheath and the melting point of the core is 30
The temperature tends to be below ℃, and the above problems will occur. On the other hand, when it exceeds 45 mol%, the spinnability is deteriorated and the fibers are fused to each other, and the texture of the obtained nonwoven fabric is deteriorated.

Then, the polyester of the core portion and / or the sheath portion contains the phosphorus compound represented by the above formula (A), and the total amount of the phosphorus compound in the composite fiber is 2 to 10 mol%.
It is contained. However, the content of each core and sheath should be 10 mol% or less.

If the phosphorus compound content is less than 2 mol% as the whole composite fiber, the flame retardancy becomes insufficient. on the other hand,
When it exceeds 10 mol%, the spinnability is deteriorated and the fibers are fused to each other to deteriorate the texture of the obtained nonwoven fabric. Further, if the content of each core-sheath component also exceeds 10 mol%, the above-mentioned problems will occur.

Examples of the phosphorus compound represented by the above formula (A) include those represented by the following formulas (B) and (C). When the phosphorus compound is contained in both the core and the sheath, the types of phosphorus compound contained in both the parts may be the same or different.

[0013]

[Chemical 3]

[0014]

[Chemical 4]

Polyester terephthalate (PET) is preferably the main constituent of the polyester of the core and the sheath. Further, pigments such as titanium oxide, antioxidants such as hindered phenolic compounds, and other various additives may be contained as long as the effects of the present invention are not impaired.

The volume ratio (core / sheath) of the core and the sheath is 35/65 to 65/35, and more preferably 40 /.
60 to 60/40. When the volume ratio of the core is less than 35, the texture of the nonwoven fabric is impaired. Volume ratio of the core is 65
If it exceeds, the adhesive component of the sheath portion decreases and the resulting nonwoven fabric has poor mechanical properties such as strength.

The cross-sectional shape of the core-sheath type composite staple fiber of the present invention is not particularly limited, but a round cross section, a hexalobal cross section, etc. are preferably used. Although the fineness and the fiber length are not particularly limited, it is preferable that the fineness is 1.1 to 6.6 dtex and the fiber length is 25 to 76 mm in consideration of the texture and quality of the obtained nonwoven fabric.

Next, a method for producing the core-sheath type composite staple fiber of the present invention will be described. The core / sheath polyester component containing or not containing the phosphorus compound as described above is melt-spun into a conjugate fiber by using a conventional conjugate spinning apparatus. After the spun yarn is cooled and solidified, a spinning oil is applied, and the yarn is bundled into a yarn bundle and stretched. Subsequently, a finishing oil agent is applied, crimped with a push-in type crimper or the like, and then cut into short fibers.

Next, the nonwoven fabric of the present invention will be described.
The nonwoven fabric of the present invention contains the above-mentioned thermo-adhesive core-sheath type composite staple fiber of the present invention. As a result, it is possible to impart to the non-woven fabric a flame retardancy that is not present in non-woven fabrics using binder fibers in which polyester is used as the core component and isophthalic acid copolyester is used as the sheath component, which is generally used.

The nonwoven fabric of the present invention has a LOI value of 25 or more, which indicates flame retardancy. The LOI value is one of the criteria for evaluating the flame retardant performance and is called the oxygen index.
When the LOI value is less than 25, the nonwoven fabric has poor flame retardancy. Among them, the LOI value is preferably 27 or more.

The nonwoven fabric of the present invention is preferably composed of the main fiber and the composite staple fiber of the present invention in consideration of mechanical properties and texture, but may be composed of only the composite staple fiber of the present invention. Therefore, the mixing ratio of the main fiber and the composite short fiber of the present invention is preferably 0 to 80 mass% of the main fiber and 100 to 20 mass% of the heat-bondable composite short fiber. When the heat-adhesive conjugate short fibers are less than 20% by mass, the number of adhesive intersections between fibers constituting the nonwoven fabric is reduced, and the mechanical properties of the resulting nonwoven fabric are impaired.

Although the main fiber is not particularly limited, polyester-based short fibers are preferable from the viewpoint of dimensional stability, weather resistance, durability, mechanical properties and recyclability of the nonwoven fabric. As the polyester short fibers, it is preferable to use fibers made of polyethylene terephthalate.
The fineness, strength and the like are appropriately selected according to the performance and application of the non-woven fabric to be obtained.

The nonwoven fabric of the present invention may be a dry nonwoven fabric or a wet nonwoven fabric. Then, the basis weight or the like may be appropriately selected according to the intended use. Less than,
A method for obtaining a dry nonwoven fabric will be described.

First, the main fiber and the heat-adhesive core-sheath type composite staple fiber of the present invention are mixed, or only the composite staple fiber of the present invention is used to make a web by applying a card machine. After that, a continuous fiber heat treatment is carried out at a temperature higher than the flow starting temperature of the sheath component of the heat-adhesive core-sheath type composite short fibers and not higher than the flow starting temperature of the sheath component + 25 ° C to obtain a short fiber non-woven fabric.

[0025]

EXAMPLES Next, the present invention will be specifically described with reference to examples. The method of measuring and evaluating each characteristic value in the examples is as follows. (1) Melting point Using a differential scanning calorimeter (DSC7 manufactured by Perkin Elmer Co., Ltd.), the temperature giving the extreme value of the melting absorption curve measured at a temperature rising rate of 20 ° C./min was taken as the melting point. (2) Flow start temperature It was measured by the above method. (3) Intrinsic viscosity An equal weight mixture of phenol and ethane tetrachloride was used as a solvent, and measurement was performed at a temperature of 20 ° C. (4) Fineness It was measured by the method of JIS L-1015-7-5-1A. (5) Fiber length Measured by the method of JIS L-1015-7-4-1C. (6) Operability Judgment was made based on the situation during spinning and drawing. ◯: The number of yarn breaks during spinning is 3 times / day · weight or less, and there is no occurrence of roller winding during stretching ×: The number of yarn breaks during spinning exceeds 3 times / day · weight or is drawn When the winding of the roller single yarn occurs at some time (7) LOI value (flame retardant performance) JIS K-7201-7
According to the method of No. 2, it was measured with an ON-1 type combustion tester manufactured by Suga Test Instruments Co., Ltd. (8) Tensile Strength of Nonwoven Fabric According to the method of JIS L-1913-6-3, the obtained nonwoven fabric was tested with a test piece having a width of 2.5 cm and a sample length of 15 cm.
0 pieces prepared, gripping interval 10 cm, pulling speed 10 cm /
The maximum strength was individually measured under the condition of minutes, and the average value was obtained. ◯: Average value is 2000 cN or more ×: Average value is less than 2000 cN (9) Texture of non-woven fabric The obtained non-woven fabric is cut into 15 × 15 cm squares, and the softness of the texture is sensory evaluated according to the following criteria by the touch of a panel. did. ○: Good ×: Poor

Example 1 A polyester having a melting point of 235 ° C., an intrinsic viscosity of 0.7 and 4.0 mol% of the phosphorus compound of the formula (B) copolymerized was used as a core, with a flow starting temperature of 132 ° C. and an intrinsic viscosity of 0.57. A polyester obtained by copolymerizing 4.0 mol% of the phosphorus compound of the formula (B) and 29.0 mol% of isophthalic acid is used as a sheath, and the core-sheath volume ratio (core / sheath) is 50/50, and the spinning temperature is 270 ° C. Discharge rate 201g / min, spinning speed 1170m /
Under the condition of a minute, it was spun by a composite spinning nozzle having a round cross section with 225 holes to obtain an undrawn yarn. The obtained undrawn yarn is bundled into a yarn bundle of 11 ktex, and then the draw ratio is 3.5.
Folding is performed at a draw temperature of 55 ° C., crimped by a push-in type crimper, and then cut to obtain a single yarn fineness of 4.4 dte.
x, a heat-bondable core-sheath type composite short fiber having a fiber length of 51 mm was obtained. 30% by mass of this heat-adhesive core-sheath type composite staple fiber, 70% by mass of polyester staple fiber made of PET having a fineness of 4.4 dtex, a fiber length of 51 mm, a strength of 5.0 cN / dtex and an elongation of 35%.
50 g / m2
To obtain a ^second polyester staple fiber nonwoven.

Examples 2 to 7 and Comparative Examples 1 to 6 The copolymerization amount of the phosphorus compound in the polyester of the core portion and the sheath portion was changed to the value shown in Table 1, and the heat treatment temperature at the time of producing the nonwoven fabric was set to Table 1. A heat-adhesive core-sheath type composite short fiber and a short fiber non-woven fabric were obtained in the same manner as in Example 1 except that the values were changed.

Examples 8 to 9 and Comparative Examples 7 to 8 Except that the volume ratio of the core portion to the sheath portion was changed to the value shown in Table 1 and the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1. A heat-adhesive core-sheath type composite short fiber and a short fiber non-woven fabric were obtained in the same manner as in Example 1.

Examples 10 to 11, Comparative Examples 9 to 10 The copolymerization amount of the phosphorus compound in the polyester of the core and the sheath and the volume ratio of the core and the sheath were changed to the values shown in Table 1,
Heat-adhesive core-sheath type composite staple fibers and staple fiber nonwoven fabrics were obtained in the same manner as in Example 1 except that the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1.

Example 12 The phosphorus compound in the polyester of the core portion and the sheath portion was added to the above (C).
A heat-adhesive core-sheath type composite staple fiber and a polyester-based staple fiber nonwoven fabric were prepared in the same manner as in Example 1 except that the phosphorus compound of the formula was changed and the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1. Obtained.

Example 13 The same as Example 1 except that the phosphorus compound in the polyester of the sheath portion was changed to the phosphorus compound represented by the formula (C) and the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1. A heat-bondable core-sheath type composite staple fiber and a polyester-based staple fiber nonwoven fabric were obtained by various methods.

Example 14 Same as Example 1 except that the phosphorus compound in the core polyester was changed to the phosphorus compound of the above formula (C) and the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1. A heat-bondable core-sheath type composite staple fiber and a polyester-based staple fiber nonwoven fabric were obtained by various methods.

Examples 15 to 16 and Comparative Examples 11 to 12, except that the amount of isophthalic acid copolymerization of the polyester in the sheath portion was changed to the value shown in Table 1 and the heat treatment temperature at the time of producing the nonwoven fabric was changed to the value shown in Table 1. In the same manner as in Example 1, a heat-bondable core-sheath type composite staple fiber and a polyester-based staple fiber nonwoven fabric were obtained.

Table 1 shows the characteristic values and evaluations of the heat-bondable core-sheath type composite staple fibers and polyester staple fiber nonwoven fabrics obtained in Examples 1 to 16 and Comparative Examples 1 to 12.

[0035]

[Table 1]

As is clear from Table 1, Examples 1 to 16
The heat-bondable core-sheath type composite staple fiber of the present invention satisfies the requirements of the present invention and can be obtained with good operability, and the nonwoven fabric obtained from this staple fiber has excellent flame retardancy and mechanical performance. Then
It was also excellent in soft texture. On the other hand, since the short fibers of Comparative Example 1 had a small amount of the phosphorus compound copolymerized, the non-woven fabric had insufficient flame retardancy. The short fiber of Comparative Example 2 had a too large amount of the phosphorus compound copolymerized, and thus a broken yarn was generated during spinning, resulting in poor operability. Since the short fibers of Comparative Examples 3 and 4 had a small amount of copolymerization of the phosphorus compound, the non-woven fabric had insufficient flame retardancy. The short fiber of Comparative Example 5 had too much copolymerization amount of the phosphorus compound of the polyester in the core portion, and the short fiber of Comparative Example 6 had too much copolymerization amount of the phosphorus compound of the polyester in the sheath portion. Breakage occurred and the operability was poor. Since the short fibers of Comparative Example 7 had a small proportion of the sheath portion, the thermal bonding performance was low and the mechanical performance of the nonwoven fabric was not sufficient.
The short fibers of Comparative Example 8 had too high a ratio of the sheath portion, and thus had too high heat-adhesive performance, and the texture of the nonwoven fabric was poor. Comparative Example 9,
Since the short fiber of 10 had a small amount of the phosphorus compound copolymerized, the non-woven fabric had insufficient flame retardancy. The short fibers of Comparative Example 11 had a low amount of copolymerized isophthalic acid in the polyester of the sheath, and thus the flow initiation temperature of the polymer of the sheath was high, and as a result, the thermal adhesion performance was lowered and the mechanical performance of the nonwoven fabric was poor. It was The short fiber of Comparative Example 12 had a large amount of isophthalic acid copolymerized with the polyester in the sheath portion, and thus had poor operability.

[0037]

The heat-adhesive core-sheath type composite staple fiber of the present invention comprises:
By defining the composition of the polyester of the core and the sheath, the amount of copolymerization of the phosphorus compound, and the volume ratio of the core to the sheath, it has excellent flame retardancy and thermal adhesiveness, and can be obtained with good operability. it can.
Further, the nonwoven fabric composed of the heat-adhesive core-sheath type composite short fibers of the present invention is excellent in flame retardancy, mechanical properties, and soft texture, and is a field requiring flame retardancy (eg, furniture material, wall. Material,
It can be widely used for automobile interior materials, etc.).

Claims (2)

[Claims] 1. The flow starting temperature of the polyester constituting the sheath is lower than the melting point of the polyester constituting the core by 30 ° C. or more, and the polyester in the sheath contains isophthalic acid in an amount of 15-4.
A thermoadhesive core-sheath type composite short fiber, which is a composite fiber copolymerized with 5 mol% and simultaneously satisfies the following (1) to (3). (1) The polyester of at least one of the core portion and the sheath portion contains a phosphorus compound represented by the following formula (A) and is contained in the composite fiber in an amount of 2 to 10 mol%. (2) The content of the phosphorus compound represented by the following formula (A) in the core polyester and / or the sheath polyester is 10 mol% or less. (3) The volume ratio (core / sheath) of the core and the sheath is 35/65.
65/35. [Chemical 1] (In the formula, R ¹ and R ³ are hydrocarbon groups having 1 to 18 carbon atoms, R ²
Represents an ester-forming group, and A represents a trivalent organic residue. The compound may be an acid anhydride. ) 2. A short-fiber non-woven fabric comprising the heat-adhesive core-sheath type composite short fiber according to claim 1 and having a LOI value of 25 or more showing flame retardancy.