JPH11279920A - Non-woven fabric using fibrous binder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a non-woven fabric of polyester, suitable as a material for cushions and interiors, and excellent in resistance to settling when used for extended periods or in a hot atmosphere. SOLUTION: This non-woven fabric is composed of main fibers bound to each other by binder fibers point to point, wherein the binder fiber is composed of polylactic acid having a melting point of 120 deg.C or more, heat of fusion of 10 J/g or more and high optical purity. The main fiber is preferably composed of polyethylene terephthalate, polyester mainly composed of polyethylene terephthalate or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a nonwoven fabric using binder fibers. Nonwoven fabric using this binder fiber is difficult to set even when used in a long-term or high-temperature atmosphere, because the adhesive strength does not decrease,
In particular, it is suitable as a cushion material or a base material for automobile interiors.

[0002]

2. Description of the Related Art Conventionally, non-woven fabrics in which fibers mainly used as fillers for furniture such as filters, interlinings, shoulder pads, backrests of sofas and chairs, cushions, etc., and cushions for beddings and automobile seats are point-bonded with binder fibers. in use. Such a known nonwoven fabric is composed of a main fiber and a binder fiber, and the one mainly adopted as the binder fiber is one having ethylene terephthalate / isophthalate copolymerized polyester as a binder component. It is. This polyester is an amorphous polymer, does not show a definite crystal melting point, and begins to soften when the temperature exceeds the glass transition point (about 65 to 70 ° C.). The nonwoven fabric obtained by heat-sealing the main fiber together with such a binder fiber has a drawback that, for example, when used in a high-temperature atmosphere, the bonding strength is reduced and the nonwoven fabric is deformed. In general, polyurethane foam is generally used as cushioning material for furniture, such as sofas, backrests of chairs, cushions, etc., and cushioning materials for beds and automobile seats. However, polyurethane foam has various problems from the standpoint of safety and environmental protection, such as the generation of nitrogen-containing toxic gas during combustion, or the destruction of the ozone layer in the upper layer by the use of chlorofluorocarbon during production. Has been pointed out.

[0003] In recent years, nonwoven fabrics mainly composed of polyester fibers have been proposed as a material replacing the polyurethane foam. For example, JP-A-57-35047 discloses that
A nonwoven fabric obtained by needling a web of polyester fibers or a nonwoven fabric obtained by fusing together with a binder fiber is proposed, and a nonwoven fabric using a polyester elastomer as a binder component is proposed in JP-A-4-240219. Have been. However, among such known polyester nonwoven fabrics, those obtained by needling a web of polyester fibers have a drawback that some of the fibers are easily dropped or scattered.
Further, those which are heat-sealed together with a binder fiber in order to prevent such a drawback have a drawback that they are easily damaged by compression in a high-temperature atmosphere and their cushioning properties deteriorate with the lapse of time of use. Further, Japanese Unexamined Patent Publication No. Hei.
Japanese Patent No. 19 proposes a binder using the above-mentioned polyester elastomer as a binder component for the purpose of solving the drawbacks of known binder fibers, but the polyester elastomer disclosed herein is a poly (alkylene oxide) It is a copolymer of glycol and has the disadvantage that it is relatively easily thermally decomposed and is difficult to heat seal.

[0004]

SUMMARY OF THE INVENTION According to the present invention, such a nonwoven fabric made of a known binder fiber can be easily set when used in a high-temperature atmosphere, and the heat-sealing processability is good. And a non-woven fabric.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem, and has the following constitution as its gist. What is claimed is: 1. A nonwoven fabric comprising a main fiber and a point fiber joined by a binder fiber, wherein the binder fiber is made of polylactic acid having a high optical purity and a melting point of 120 ° C. or more and a heat of fusion of 10 J / g or more.

[0006]

Next, the binder fibers used in the nonwoven fabric of the present invention will be described in detail. First, the binder fiber in the present invention has a melting point of 120 ° C. as described above.
As described above, it is composed of polylactic acid having a high optical purity with a heat of fusion of 10 J / g or more. Here, the melting point of polylactic acid is 1
The temperature must be 20 ° C. or higher, preferably 130 ° C. or higher. When the melting point is less than 120 ° C., the nonwoven fabric using the binder fiber is unfavorably liable to be sagged when used in a high-temperature atmosphere, for example, a chair or an automobile seat exposed to the hot sun, and the heat resistance becomes insufficient. . The upper limit of the melting point is preferably lower than the melting point or decomposition temperature of the main fiber by 20 ° C. or more. This is because the difference between this melting point and the melting point or decomposition temperature of the main fiber is 20%.
If the temperature is lower than ℃, the main fibers are softened during the heat-sealing process, and it is difficult to mold into a desired form, or even if molding is possible, the colored fibers may deteriorate the quality of the product. It is.

The heat of fusion of polylactic acid must be at least 10 J / g, and if the heat of fusion is less than 10 J / g,
The amorphous property becomes high and the degree of softening before reaching the melting point is high, and the heat resistance of the non-woven fabric using this binder fiber becomes insufficient. The lactic acid monomer has an optically active carbon, and has D-form and L-form optical isomers. By copolymerizing the L-form with less than 2 mol% of the D-form, polylactic acid having a melting point of 165 ° C. or higher can be obtained. And
When the copolymerization ratio of the D-form is increased to about 10 mol%, the melting point becomes about 140 ° C. Furthermore, lowering the optical purity
When the copolymerization ratio of the polymer is 18 mol% or more, the melting point is 12
At less than 0 ° C., the heat of fusion is less than 10 J / g, which is almost completely amorphous, and the heat resistance of the non-woven fabric using this binder fiber is insufficient.

The preferred range of the molecular weight of the polylactic acid used in the present invention is ASTM as an index of the molecular weight.
When expressed by a melt flow rate value measured by the D-1238 method (temperature 210 ° C., load 2160 g), it is 1 to 80 g / 1.
It is preferably 0 minutes, more preferably 5 to 50 g /
10 minutes.

The binder fiber in the present invention may be one in which one kind of polylactic acid forms the whole of a single fiber, or two kinds of polylactic acid having melting points different from each other may be a core-sheath type, a side-by-side type. It may be a composite of a mold, a sea-island type, a split type, and the like. Among them, the core-shell type polylactic acid having a core portion of a melting point of 170 ° C. or higher, and the sheath portion of a polylactic acid having a melting point of about 130 ° C. has a high adhesive strength, that is, a shape retention property when formed into a nonwoven fabric, and It is preferable from the viewpoint of the stiffness when the nonwoven fabric is compressed. The cross-sectional shape of the fiber may be an irregular cross-section such as a triangular cross-section or a flat cross-section in addition to a normal round cross-section.

The single fiber fineness of the binder fiber in the present invention is not particularly limited, but is preferably in the range of 1 to 100 denier. This is because if the single-fiber fineness is less than 1 denier, the production efficiency of the fiber is low and the cost is high. On the other hand, if the single-fiber fineness exceeds 100 denier, it is difficult to draw in the process of producing ordinary short fibers. However, special production equipment is required separately, which also results in high cost, which is not preferable.

Next, the nonwoven fabric of the present invention will be described in detail. As described above, the nonwoven fabric of the present invention is obtained by subjecting main fibers to point bonding with binder fibers. The main fibers include synthetic fibers made of a fiber-forming polymer such as polyester fiber, nylon fiber, acrylic fiber, vinylon fiber, and polypropylene fiber; regenerated fibers such as rayon, polynodick, tencel, and lyocell; and semi-synthetic fibers such as acetate. Natural fibers such as wool, cotton, hemp, and wood pulp can be employed. Among the synthetic fibers, polyester fibers include, for example, those having ethylene terephthalate unit, butylene terephthalate unit or ethylene naphthalate, particularly ethylene-2,6-naphthalate unit as a main component. In particular, polyethylene terephthalate fiber is preferably used from the viewpoint of properties. In addition, as long as the characteristics are not impaired, isophthalic acid, 5-sulfoisophthalic acid,
Other components such as diethylene glycol may be copolymerized. In the case of a synthetic fiber, a regenerated fiber, or a semi-synthetic fiber, the cross-sectional form may be a round cross section or an irregular cross section, and may be hollow or solid. The single fiber fineness of the main fiber is not particularly limited, and may be appropriately determined based on required characteristics according to the application. Generally, a denier of 2 to 200 is used.

The proportion of the binder fiber used in the nonwoven fabric of the present invention may be 10 to 70% by weight of the whole nonwoven fabric, but can be changed according to the required characteristics depending on the application. If the use ratio is low within the range of 10 to 70% by weight, the obtained nonwoven fabric has a soft texture, and is used for, for example, a surface material of a sanitary material or a cosmetic puff. When the nonwoven fabric is higher than the above range, the obtained nonwoven fabric has high rigidity, and is preferably used for, for example, a substrate (board-like) for an automobile interior or a house interior.

In the nonwoven fabric of the present invention, the main fiber and the binder fiber are mixed at a ratio determined according to the intended use or required characteristics, and a web is formed by a carding machine or the like, and then the polylactic acid of the binder fiber is melted. Thus, the main fibers can be efficiently joined to each other by point joining. In manufacturing, needling may be performed before heat treatment. As the heat treatment equipment, heating flat roller, heating emboss roller,
A hot air circulation dryer, a hot air once-through dryer, a suction drum dryer, a Yankee drum dryer, and the like are used. At the time of the treatment, a treatment temperature and a treatment time according to the melting point of the polylactic acid may be appropriately selected.

The nonwoven fabric of the present invention is prepared from a paper-like web obtained by thermocompression bonding a relatively low-weight web of about 50 g / m ² or less with a heating flat roller to a thickness of about 5 mm to 150 mm and a density of 0.010 g / cm ^3. The above-mentioned so-called solid cotton is included. The upper limit of the thickness is not particularly limited, but is preferably up to about 150 mm in terms of manufacturing equipment, manufacturing cost, and ease of use. When used as solid cotton, the density is 0.010 g / cm.
^It is preferably at least ³ . 0.010 g / cm density
If the number is less than ³ , it may be lost due to repeated compression. The upper limit of the density is not specified because it differs depending on the degree of cushioning required by the application, but is preferably 0.2 g / cm ³ or less from the viewpoint of manufacturing equipment, manufacturing cost, and the like. In order to regulate the thickness and density of the nonwoven fabric of the present invention, the basis weight of the web before heat treatment is appropriately selected in consideration of the area shrinkage of the web due to heat treatment, and a thickness regulation roll is incorporated into the heat treatment apparatus, The heat treatment may be performed by sandwiching a web between plates or wire nets having a thick spacer.

[0015]

The nonwoven fabric of the present invention has a main fiber which is point-joined with a polylactic acid-based binder which is easily heat-sealed.
Since the bonding strength of the point-bonded portions is high, the bonded portions are unlikely to be peeled even after repeated compression. Therefore, the shape of the nonwoven fabric is favorably maintained, and sag hardly occurs. Further, since the binder component is composed of polylactic acid having a melting point of 120 ° C. or more, when using a nonwoven fabric, for example, 70 to 80 ° C.
It is hard to be deformed even when compressed under high temperature atmosphere. Therefore, for example, when used as an interlining or a shoulder pad, it is difficult to lose its shape after washing at high temperature. Further, it is also suitable for use as a filter for filtering a high-temperature fluid. In addition, when used as a cotton wool for cushions, there is little settling even during the passage of time or in a high-temperature atmosphere, and if it has a certain thickness or more, there is no feeling of flooring. And cushioning materials for car seats,
It is suitable as a mattress. Utilizing the low sagging and deformation under high temperature atmosphere, vibration absorption and soundproofing materials for car floors,
It can also be used as a base material for molded ceilings, base materials such as door panels and quarter panels, molding materials for trunk room interiors, and sound absorbing materials around engines. In addition, it is suitable as a sanitary material and a floppy disk liner utilizing the high adhesive strength to rayon and pulp.

[0016]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. The methods for evaluating various physical properties described in the examples are as follows. (1) Melt flow rate value of polylactic acid (g / 10
Min): Measured according to the method described in ASTM D-1238. The measurement conditions were as follows: temperature 210 ° C., load 216
0 g. (2) Relative viscosity of polyester: a mixture of phenol and ethane tetrachloride of equal weight was used as a solvent, and the sample concentration was 0.5 g / 1.
The measurement was performed under the conditions of 00 cc and a temperature of 20 ° C. (3) Melting point (° C), glass transition point (° C) and heat of fusion (J
/ G): Differential scanning calorimeter DSC manufactured by PerkinElmer
The measurement was performed under the condition of a heating rate of 20 ° C./min using Model-2. (4) Set resistance during repeated compression: Set resistance of polyester solid cotton during repeated compression was evaluated by the following method. That is, after measuring the thickness T1 (mm) of the solid cotton, a test piece (10 cm × 10 cm) is sandwiched between parallel plane plates, and a load of 15 kg is applied 60 times per minute to perform a total of 50,000 repeated compression tests. Is measured, and the bulkiness retention C (%) is calculated by the following equation (A).
It was a measure of sag resistance. The larger the value of C, the more difficult it is to set. C (%) = (T2 / T1) × 100 (a) (5) Set resistance under high temperature atmosphere: Set resistance of polyester solid cotton under high temperature atmosphere was evaluated by the following method. That is, after measuring the thickness T1 (mm) of the solid cotton,
A test piece (10 cm × 10 cm) is sandwiched between parallel flat plates, compressed and fixed to 50% of its original thickness, placed in a constant temperature bath at a temperature of 70 ° C., left for 6 hours, taken out, removed from the parallel flat plates, and removed at room temperature. 30 minutes in the room, its thickness T3 (mm)
Is measured, and the bulk retention C under a high-temperature atmosphere is calculated by the following equation (b).
p (%) was calculated and used as a measure of sag resistance. The larger the value of Cp, the more difficult it is to set. Cp (%) = (T3 / T1) × 100 (b) In the evaluation of sag resistance, in the case of thin cotton, a plurality of test pieces were laminated.

Example 1 Melting point 170 ° C., glass transition point 66 ° C., heat of fusion 42 J /
g, optical purity 99% (mainly L-form: determined by the ratio of L-form and D-form charged during polymerization of lactic acid monomer), and a melt flow rate value (hereinafter abbreviated as MFR) of 21 g /.
After drying the polylactic acid chip for 10 minutes under reduced pressure, it was melted using an ordinary melt spinning apparatus, and melt-spun at a spinning temperature of 210 ° C. through a spinneret having a plurality of spin holes having a circular cross section. After cooling the spun yarn, the yarn was drawn at a drawing speed of 1000 m / min to obtain an undrawn fiber yarn. The obtained yarn is bundled into a 100,000-denier tow, stretched at a draw ratio of 2.8, at a draw temperature of 90 ° C., heat-treated with a heat drum at a temperature of 130 ° C., and then wound using a push-in crimper. After shrinking, it is cut to a length of 51 mm and has a single yarn fineness of 4.3.
A dtex polylactic acid binder fiber was obtained. Separately, polyethylene terephthalate having a relative viscosity of 1.38 (hereinafter referred to as PE
Abbreviated as T. ) Was dried under reduced pressure, melted using a conventional melt spinning apparatus, and melt-spun at a spinning temperature of 2800 ° C. through a spinneret having a round cross-section and a plurality of hollow spinning holes. PE of hollow cross section by known method
Polyester-based fibers having T fibers [strength of 4.5 cN / dtex, elongation of 58%, fineness of 6.5 dtex, cut length of 51 mm, and hollow ratio (the ratio of the hollow portion in the fiber cross section) of 27%] were obtained. Next, the binder fiber and the main fiber obtained above were mixed in a weight ratio of 30:70, passed through a carding machine, and then laminated with a cross wrapper to obtain a basis weight of 600 g / m ^2.
The needle was passed through a needle locker room having a barbed needle and needled at a needle density of 240 needles / cm ² . Further, this web was put between wire meshes with a spacer of 20 mm in thickness, and heat-treated for 5 minutes in a hot air circulating drier at a temperature of 200 ° C. while regulating the thickness to obtain a 20 mm thick Example 1. Was obtained. Table 1 shows the evaluation results of the obtained solid cotton.

Example 2 Melting point 150 ° C., heat of fusion 32 J / g, optical purity 92% (L
Body: Determined by the ratio of L and D bodies charged during polymerization of lactic acid monomer. Example 1) except that a polylactic acid chip having an MFR of 20 g / 10 min was used, the heat treatment temperature by a heat drum during binder fiber production was 110 ° C., and the temperature during web heat treatment was 180 ° C. Similarly, solid cotton of Example 2 was obtained. Table 1 shows the evaluation results of the obtained solid cotton.

Example 3 Melting point: 135 ° C., heat of fusion: 18 J / g, optical purity: 87% (L
Body: Determined by the ratio of L and D bodies charged during polymerization of lactic acid monomer. Example 1) except that a polylactic acid chip having an MFR of 22 g / 10 min was used, the heat treatment temperature by a heat drum at the time of binder fiber production was 90 ° C., and the temperature at the time of heat treatment of the web was 160 ° C. Similarly, solid cotton of Example 3 was obtained. Table 1 shows the evaluation results of the obtained solid cotton.

Comparative Example 1 A clear melting peak by DSC was not observed at an optical purity of 50% (L-form 50%, D-form 50%) and the heat of fusion was about 3 J / g.
In the same manner as in Example 1 except that a high amorphous polylactic acid chip was used, heat treatment was not performed by a heat drum during binder fiber production, and the temperature during the heat treatment of the web was set to 160 ° C. The solid cotton of Comparative Example 1 was obtained.
Table 1 shows the evaluation results of the obtained solid cotton.

Comparative Example 2 Ethylene terephthalate unit / polylactic acid chip
Ethylene isophthalate unit (molar ratio of acid component 6/4)
Polyester chip (relative viscosity 1.37, DS
No melting point due to C is observed. ), The heat treatment with a heat drum was not performed during the production of the binder fiber, and the temperature during the heat treatment of the web was set to 160 ° C., and the solid cotton of Comparative Example 2 was obtained in the same manner as in Example 1. Was. Table 1 shows the evaluation results of the obtained solid cotton.

[0022]

[Table 1]

As is clear from Table 1, all of the solid cottons obtained in Examples 1 to 3 had good sag resistance. On the other hand, the solid cotton obtained in Comparative Examples 1 and 2 had poor heat resistance at high temperatures due to low heat resistance of polylactic acid and copolymerized polyester as an adhesive component.

Examples 4 to 6 Example 1 except that the thickness of the spacer for regulating the thickness of the web after needling was heat-treated was 8 mm, 35 mm and 69 mm (Examples 4, 5 and 6 respectively). In the same manner as in the above, solid cotton of Examples 4 to 6 was obtained. Table 2 shows the evaluation results of the obtained solid cotton.

Example 7 Example 1 except that the basis weight of the web before the heat treatment was 120 g / m ² and the thickness of the spacer for regulating the thickness when the web after the needling was heat treated was 4 mm. In the same manner as in the above, solid cotton of Example 7 was obtained. Table 2 shows the evaluation results of the obtained solid cotton.

[0026]

[Table 2]

As apparent from Table 2, the solid cotton obtained in Examples 4 to 7 had satisfactory sag resistance as solid cotton.

[0028]

The nonwoven fabric using the binder fiber of the present invention is resistant to repeated compression or compression in a high-temperature atmosphere, and does not reduce the adhesive strength. For this reason, for example, when used as a wadding for cushions, it absorbs impact and is comfortable to sit on. Moreover, it has little settling over time and has no feeling of flooring, and is suitable as wadding and bedding for furniture, cushioning material for automobile seats, and mattresses. In addition, during the production, the heat fusion processability is good.

Claims (3)

[Claims] 1. A nonwoven fabric in which main fibers are point-joined with binder fibers, wherein the binder fibers are made of polylactic acid having a high optical purity and a melting point of 120 ° C. or more and a heat of fusion of 10 J / g or more. And non-woven fabric. 2. The nonwoven fabric according to claim 1, wherein the main fiber is a fiber made of polyethylene terephthalate or a polyester mainly containing the same, or a fiber made of a polybutylene terephthalate or a polyester mainly containing the same. 3. The nonwoven fabric according to claim 1, having a density of at least 0.010 g / cm ³ and a thickness of at least 5 mm.