JP5116984B2 - Nonwoven fabric and method for producing the same - Google Patents

Description

  The present invention relates to a nonwoven fabric made of a mixed fiber of a fiber made of polyoxymethylene resin and another organic fiber, and a method for producing the same.

  Nonwoven fabrics are used in a wide variety of applications from industrial use to clothing use. Conventionally, various fibers such as polyester fibers, polyamide fibers, polyolefin fibers, wool, and cotton have been used as fibers constituting such nonwoven fabrics.

  However, the properties and characteristics of non-woven fabrics are strongly dependent on the type and shape of the fibers that make up the non-woven fabric, and are known from the past as the fields of use and conditions of use of non-woven fabrics expand and diversify. The obtained non-woven fabric cannot meet its purpose and tends to require a non-woven fabric having higher properties.

  As one of such characteristics, there is an improvement in the shape recoverability and shape stability of the nonwoven fabric.

  For example, in various types of filters that are typical uses of nonwoven fabrics, the filtration function is determined by the structure of the fiber assembly forming the nonwoven fabric. The structure of the fiber assembly may be crushed by the pressure, and the filtration function may be lowered, and the desired characteristics as a filter may not be maintained.

  In addition, nonwoven fabrics are also used for clothing interlinings, etc., and the main purpose of use is to maintain the form, but the intended function may be impaired by the shape of the nonwoven fabric breaking down due to long-term use. is there.

  As a conventional technique related to the recoverability of such a nonwoven fabric, Japanese Patent Application Laid-Open No. 7-145543 discloses a technique related to improving the stretch recovery property of the nonwoven fabric (Patent Document 1).

  In the technique disclosed in this document, large intertwined fiber bundles substantially intersect, and in addition, small intertwined fiber bundles substantially intersect between the large fiber bundles, and further, intertwined at the intersection of each fiber bundle. It relates to the nonwoven fabric made. By including the ultrafine fibers obtained by mechanically dividing the splittable fibers into fine fibers, it is possible to obtain characteristics that are superior in drape and stretch recovery properties and are less likely to cause plastic deformation.

However, since this technique requires a special fiber process called finening with a splittable fiber, it has been difficult to perform general-purpose implementation and versatility.
JP-A-7-145543

  The objective of this invention is providing the nonwoven fabric excellent in shape recovery property, form stability, etc. which solve the above subjects.

  As a result of intensive research to achieve the above object, the present inventor mixed the fibers made of polyoxymethylene resin with other organic fibers, and formed the nonwoven fabric from the mixed fibers, whereby the above problems were solved. The present invention has been found.

  That is, the present invention relates to a nonwoven fabric comprising a mixed fiber of 1 to 99 parts by weight of a fiber (A) made of a polyoxymethylene resin and 99 to 1 part by weight of an organic fiber (B) made of a substance other than the polyoxymethylene resin, and the production thereof. It is about the method.

  According to the present invention, it is possible to provide a nonwoven fabric excellent in shape recoverability, form stability, and the like without requiring complicated steps.

  Hereinafter, the present invention will be described in detail. As described above, the nonwoven fabric of the present invention is characterized by being formed of a mixed fiber of a fiber (A) made of a polyoxymethylene resin and an organic fiber (B) made of a substance other than the polyoxymethylene resin.

There is no restriction | limiting in particular as polyoxymethylene resin which comprises fiber (A), Any, such as a polyoxymethylene homopolymer and a polyoxymethylene copolymer (a terpolymer etc. are included), can be used. Further, the molecular structure is not particularly limited, and those having a linear structure and those having a branched or crosslinked structure can be used. Among them, various properties such as thermal stability and ease of processing of the fiber (A), durability of the fiber (A), and mixing of the fiber (A) with other organic fibers (B) From the viewpoint of processability when forming a nonwoven fabric from fibers, it is preferable to use a polyoxymethylene copolymer. More specifically, a polyoxymethylene copolymer containing 1.5 to 8.0 mol of an oxyalkylene unit represented by the following general formula (1) per 100 mol of oxymethylene units in a polymer chain mainly composed of repeating oxymethylene units. Is preferred. A more preferable ratio of the oxyalkylene unit represented by the general formula (1) is 1.8 to 5.0 mol per 100 mol of the oxymethylene unit, and particularly preferably 2.0 to 4.0 mol per 100 mol of the oxymethylene unit. When the proportion of the oxyalkylene unit represented by the general formula (1) is reduced, the crystallization speed of the polyoxymethylene copolymer is increased, and not only the occurrence of yarn breakage during spinning in the fiber production process is increased, but also immediately after spinning. As the crystallinity increases, the stretchability tends to decrease. On the contrary, when the ratio of the oxyalkylene unit is excessive, the strength of the fiber is insufficient.

The polyoxymethylene resin used in the present invention preferably has a melt index (MI) measured at 190 ° C. under a load of 2160 g of 1.0 to 120 g / 10 minutes, more preferably, according to ASTM D-1238. The amount is 2.5 to 100 g / 10 minutes, more preferably 5.0 to 90 g / 10 minutes. When the melt index (MI) is excessive, the polyoxymethylene resin has a low molecular weight, so that the yarn is easily broken during spinning and stretching, and the production becomes unstable. Further, a polyoxymethylene resin having an excessively low melt index (MI) increases the load during spinning due to high viscosity and makes spinning difficult, and also makes stretching difficult due to an increase in stretching stress.

  The method for producing the polyoxymethylene resin as described above used in the present invention is not particularly limited. For example, in the case of a polyoxymethylene copolymer, a cyclic ether compound or a cyclic formal compound generally composed of trioxane and a comonomer. Can be obtained by a bulk polymerization method mainly using a cationic polymerization catalyst. As the polymerization apparatus, any known apparatus such as a batch system or a continuous system can be used. The introduction ratio of the oxyalkylene unit represented by the general formula (1) described above depends on the amount of the comonomer to be copolymerized, and the melt index (MI) is the added amount of a chain transfer agent such as methylal used during the polymerization. Can be adjusted.

  Examples of cyclic ether compounds or cyclic formal compounds used as comonomers include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, oxetane, tetrahydrofuran, trioxepane, 1,3-dioxolane, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, etc., among which ethylene oxide, 1,3-dioxolane, diethylene glycol formal, and 1,4-butanediol formal are preferable. Further, the polyoxymethylene copolymer may have a branched or crosslinked structure.

  The polyoxymethylene copolymer obtained by polymerization was subjected to catalyst deactivation treatment, removal of unreacted monomers, washing of the polymer, drying, stabilization treatment of unstable terminal portions, etc. It is put into practical use by performing a stabilization treatment by blending a stabilizer. Representative stabilizers include hindered phenol compounds, nitrogen-containing compounds, alkali or alkaline earth metal hydroxides, inorganic salts, carboxylates, and the like.

  Furthermore, for the polyoxymethylene resin used in the present invention, general additives for thermoplastic resins, for example, colorants such as dyes and pigments, lubricants, nucleating agents, mold release agents, antistatic agents, are used as necessary. One or more surfactants, organic polymer materials, inorganic or organic fibrous, plate-like, and powdery fillers can be added as long as the object of the present invention is not impaired. .

  The fiber (A) used in the present invention can be produced as follows using the polyoxymethylene resin as described above, but is not limited thereto.

  As a method for producing the fiber (A), a general melt spinning method can be used. Specifically, an undrawn yarn is obtained by extruding and winding a polyoxymethylene resin melt-plasticized by a single or twin screw extruder from a die having a desired cross-sectional shape hole. Next, a fiber (A) made of a polyoxymethylene resin can be obtained by drawing the undrawn yarn while heating continuously or discontinuously. In the stretching step, stretching can be performed in a temperature range from room temperature to the melting point, but the optimum temperature varies depending on the stretching speed, the stretching ratio, the heating method, and the like, and accordingly adjustment is necessary. The draw ratio is preferably 3 times or more from the viewpoint of fiber diameter uniformity and strength, and is preferably 4 times or more and 12 times or less in consideration of fiber strength and elongation. The fineness of the obtained fiber is preferably about 1 to 50 dtex.

  In addition, it is desirable to crimp the obtained fiber as necessary. A preferable crimp is 5 to 30 crests / inch, and a more preferable crimp is about 10 to 20 crests / inch. Although the obtained fiber can be used in the state of continuous fiber, it is generally preferable to cut into short fibers having a fiber length of about 2 to 150 mm and use them in the production of nonwoven fabrics. A more preferable fiber length is about 3 to 120 mm.

  The above-described crimping treatment of fibers and fiber cutting can be performed in the pre-process of manufacturing the nonwoven fabric, and then the nonwoven fabric can be manufactured.

  Next, there is no particular limitation on the organic fiber (B) for forming the mixed fiber together with the fiber (A) made of the polyoxymethylene resin and forming the nonwoven fabric of the present invention, and conventionally used as a material for the nonwoven fabric. Various kinds of organic fibers that have been used, for example, synthetic fibers made of polyester resin, polyamide resin, polypropylene resin, acrylic resin, etc., and natural fibers made of wool, cotton, etc. can be used. It is also possible to do. Among these, it is preferable to use a synthetic fiber made of a polyester resin, a polyamide resin, a polypropylene resin, an acrylic resin, or the like. There are no special restrictions on the form of the fiber. Further, when the mixed fiber is prepared by mixing with the fiber (A), the fiber length and fineness do not need to be uniform, and can be appropriately determined from the processing method and the required properties of the nonwoven fabric.

  The nonwoven fabric of the present invention comprises a mixed fiber of 1 to 99 parts by weight of the fiber (A) made of the polyoxymethylene resin and 99 to 1 part by weight of an organic fiber (B) made of a substance other than the polyoxymethylene resin. It is characterized by. The shape recoverability and shape stability of the nonwoven fabric become better as the amount of the fiber (A) made of polyoxymethylene resin is increased, but the blending ratio may be determined in consideration of the purpose of use of the nonwoven fabric, cost, and the like. In general, a ratio of 10 to 90 parts by weight of the fiber (A) and 90 to 10 parts by weight of the organic fiber (B) is preferable, more preferably 20 to 80 parts by weight of the fiber (A) and 80 to 20 parts of the organic fiber (B). It is the ratio of parts by weight.

  Next, the manufacturing method of the nonwoven fabric consisting of the mixed fiber of the fiber (A) which consists of the said polyoxymethylene resin, and another organic fiber (B) is demonstrated.

  The present invention is characterized in that a mixed fiber of 1 to 99 parts by weight of a fiber (A) made of a polyoxymethylene resin and 99 to 1 part by weight of an organic fiber (B) made of another material is used for producing a nonwoven fabric. After mixing a fiber (A) and an organic fiber (B), a nonwoven fabric can be obtained by intertwining and / or joining fibers by any method.

  Any conventionally known non-woven fabric manufacturing process and manufacturing apparatus can be applied. For example, after forming the web by applying the mixed fiber to the carding process, the method of intertwining the fibers by airflow or water flow, the method of intertwining the fibers by needle punch, the method of joining the fibers by heat fusion or adhesive, etc. A dry nonwoven fabric manufacturing process to be applied singly or in combination, or fiber (A) and organic fiber (B) are dispersed in water or the like, mixed and scraped, followed by fiber entanglement in the same manner as above. It is possible to manufacture a nonwoven fabric by a wet nonwoven fabric manufacturing process or the like for performing bonding and / or joining.

  The fibers (A) and organic fibers (B) used are preferably short fibers having the above-described fiber length. Further, in the above, when performing bonding by heat fusion, a method of heating near the softening temperature of the material constituting the fiber is common, a method of forming the fiber with a composition containing a polymer having a low melting point, It is also effective to use a fiber having a core-sheath structure and a polymer having a low melting point for the outer layer (sheath).

  In addition, nonwoven fabric sheets that are manufactured by using a woven fabric made of monofilament or the like as a base material and appropriately mixing short fibers and tangling the short fibers to the mesh have a high mechanical strength in the sheet direction and are air permeable and water permeable. Therefore, the application range is wide industrially.

  As described above, the present invention is characterized in that a non-woven fabric is formed of mixed fibers including fibers (A) made of polyoxymethylene resin. Polyoxymethylene resins, especially polyoxymethylene copolymers, have the property of being easily molecularly oriented due to low stress in the fiber (A) production process by melt spinning, and the strength and toughness of the fibers are increased by increasing the distribution height. Furthermore, the texture and mechanical properties of the nonwoven fabric are greatly affected. Therefore, it is preferable to use the nonwoven fabric of the present invention having a degree of orientation of 70% or more calculated by performing wide-angle X-ray diffraction measurement as the fiber (A) that is a constituent component. When the degree of orientation is too small, the fiber (A) has brittle characteristics and may lack practicality.

  The orientation order parameter was given by the following formula, and S was calculated as the degree of orientation.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

The evaluation items and evaluation methods in the examples and comparative examples are as follows.
[Melt index (MI) measurement]
According to ASTMD-1238, measurement was performed at 190 ° C. under a load of 2160 g.
[Polymer composition analysis of polyoxymethylene copolymer]
The polyoxymethylene copolymer used for the evaluation was dissolved in hexafluoroisopropanol d2, and ¹ H-NMR measurement was performed. The composition of the constituent components was quantified from the peak area corresponding to each unit.
[Orientation]
Using a wide-angle X-ray diffractometer (Rint-1400, manufactured by Rigaku Corporation), an X-ray (Cu-Kα) pinhole beam and a flat plate imaging plate (IP) monochromatized with a Ni filter, a two-dimensional scattering pattern by the transmission method Measured by shooting. It was calculated by the following formula.

[Fiber processability]
The melt spinning and stretching process is performed by the method described in the examples, and the fiber processing state in the melt spinning process and the stretching process when the short fiber is prepared by cutting this is visually observed and evaluated according to the following criteria: did.

3: Stable fiber can be prepared 2: Severe breakage occurs in the spinning process (fiber preparation is possible)
1: Many yarn breaks in spinning and drawing processes (fiber preparation is possible in a limited way)
[Shape recovery]
The needle punched nonwoven fabric is piled up to a thickness of 5 cm, compressed at a load of 5 g / cm ^{2 and} placed for 30 seconds and left for 30 seconds. The work is restored from the height 30 seconds after releasing the load to the original height. The recovery rate was calculated assuming that the condition was 100%.
Examples 1-12
Two with paddles using a continuous mixing reactor composed of a barrel that has a shape with two circular cross-sections and a rotating shaft with paddles. while the rotating shaft was rotated at respectively 150 rpm, liquid trioxane, cyclic ether or cyclic formal as a comonomer (1,3-dioxolane, 1,4-butanediol formal, di ethylene glycol formal) was added, as a further molecular weight regulator Bulk polymerization was carried out while continuously supplying methylal and simultaneously 50 ppm of boron trifluoride (based on all monomers) to the polymerization machine to prepare the polymers shown in Table 1. The amount of the copolymer unit was adjusted by the amount of comonomer used, and the melt index (MI) was adjusted by the amount of methylal to be added. While rapidly passing the reaction product discharged from the polymerization machine through a crusher, the catalyst was deactivated by adding it to a 60 ° C. aqueous solution containing 0.05% by weight of triethylamine. Further, after separation, washing and drying, a crude polyoxymethylene copolymer was obtained.

  Next, 4 parts by weight of a 5% by weight aqueous solution of triethylamine and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) are added to 100 parts by weight of the crude polyoxymethylene copolymer. ) Propionate] was added in an amount of 0.3 parts by weight, and the mixture was melt kneaded at 210 ° C. with a twin screw extruder to remove unstable parts.

  To 100 parts by weight of the polyoxymethylene resin obtained by the above method, 0.03 part by weight of pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] as a stabilizer and melamine 0.15 part by weight was added and melt-kneaded at 210 ° C. with a twin-screw extruder to obtain a pellet-shaped polyoxymethylene resin.

  Using the obtained polymer, the resin is melt plasticized with an extruder with a cylinder set temperature of 200 ° C, measured with a gear pump, melt-spun at a nozzle temperature of 225 ° C and a hot air temperature of 200 ° C, and heated in a separate process at 138 ° C. After stretching 6 times in the furnace, it was crimped and cut to 51 mm length to obtain 2.5 dtex polyoxymethylene short fibers. In Examples 11 and 12, the cylinder set temperatures were 190 ° C. and 210 ° C., respectively.

After mixing polyester short fiber and nylon 6 short fiber (2.5dtex, 51mm length) with the composition ratio shown in Table 1 to the obtained polyoxymethylene short fiber, it is opened with a roller card to produce a web. A nonwoven fabric having a basis weight of 60 g / m ² was obtained by adjusting and performing needle punching.

The evaluation results are shown in Table 1.
Comparative Examples 1-2
The nonwoven fabric was prepared only with the fiber which consists of another raw material, without mixing the fiber which consists of polyoxymethylene resin.

  The evaluation results are shown in Table 1.

Claims (25)

A non-woven fabric comprising a mixed fiber of 1 to 99 parts by weight of a fiber (A) made of a polyoxymethylene resin and 99 to 1 part by weight of an organic fiber (B) made of a substance other than the polyoxymethylene resin,
A nonwoven fabric in which the organic fiber is made of a material selected from a polyester resin, a polyamide resin, a polypropylene resin, and an acrylic resin.   The nonwoven fabric according to claim 1, wherein the polyoxymethylene resin constituting the fiber (A) is a polyoxymethylene copolymer. The nonwoven fabric according to claim 2, wherein the polyoxymethylene copolymer contains 1.5 to 8.0 mol of oxyalkylene units represented by the following general formula (1) per 100 mol of oxymethylene repeating units.

(Wherein, R _1, R ₂ is hydrogen, an alkyl group having 1 to 8 carbon atoms, an organic group having an alkyl group of 1 to 8 carbon atoms, a phenyl group, selected from an organic group having a phenyl group, R ₁ R ₂ may be the same or different, and m represents an integer of 2 to 6.)   The nonwoven fabric according to claim 2, wherein the polyoxymethylene copolymer contains 1.8 to 5.0 mol of the oxyalkylene unit represented by the general formula (1) per 100 mol of the oxymethylene repeating unit.   The nonwoven fabric according to claim 2, wherein the polyoxymethylene copolymer contains 2.0 to 4.0 mol of the oxyalkylene unit represented by the general formula (1) per 100 mol of the oxymethylene repeating unit.   The nonwoven fabric according to claim 2, wherein the polyoxymethylene copolymer has a branched or crosslinked structure. The melt index ( 190 degreeC, load 2160g) of polyoxymethylene resin is 1.0-120g / 10min, The nonwoven fabric in any one of Claims 1-6. The melt index ( 190 degreeC, load 2160g) of polyoxymethylene resin is 2.5-100g / 10min, The nonwoven fabric in any one of Claims 1-6. The melt index ( 190 degreeC, load 2160g) of a polyoxymethylene resin is 5-90g / 10min, The nonwoven fabric in any one of Claims 1-6.   The fiber (A) made of a polyoxymethylene resin has an orientation degree of 70% or more as the orientation degree in the fiber axis direction obtained by wide-angle X-ray diffraction measurement. Non-woven fabric.   The non-woven fabric according to any one of claims 1 to 10, wherein the fineness of the fiber (A) made of polyoxymethylene resin is 1 to 50 dtex.   The nonwoven fabric according to any one of claims 1 to 11, wherein the fiber (A) made of a polyoxymethylene resin has a crimp of 5 to 30 threads / inch.   The nonwoven fabric according to any one of claims 1 to 12, wherein the fibers (A) and the organic fibers (B) are both short fibers having a fiber length of 2 to 150 mm. 1 to 99 parts by weight of the fiber (A) made of a polyoxymethylene resin and 99 to 1 part by weight of an organic fiber (B) made of a substance other than the polyoxymethylene resin are mixed. A method for producing a nonwoven fabric for joining,
The manufacturing method of the nonwoven fabric whose said organic fiber is a polyester fiber or a nylon fiber.   The method for producing a nonwoven fabric according to claim 14, wherein both the fibers (A) and the organic fibers (B) to be mixed are short fibers having a fiber length of 2 to 150 mm.   The method for producing a nonwoven fabric according to claim 14 or 15, wherein the fibers are entangled by needle punching.   The method for producing a nonwoven fabric according to claim 14 or 15, wherein the fibers are entangled by airflow.   The method for producing a nonwoven fabric according to claim 14 or 15, wherein the fibers are entangled by a water flow.   The manufacturing method of the nonwoven fabric of Claim 14 or 15 which joins a fiber by heat sealing | fusion.   The manufacturing method of the nonwoven fabric of Claim 14 or 15 which joins a fiber with an adhesive component. 1 to 99 parts by weight of fibers (A) made of polyoxymethylene resin, both short fibers having a fiber length of 2 to 150 mm, and 99 to 1 parts by weight of organic fibers (B) made of a substance other than polyoxymethylene resin are submerged in water. A method for producing a nonwoven fabric, in which fibers are entangled and / or bonded after being dispersed and mixed,
The manufacturing method of the nonwoven fabric whose said organic fiber is a polyester fiber or a nylon fiber.   The method for producing a nonwoven fabric according to claim 21, wherein the entanglement of the fibers is performed by an air flow.   The method for producing a nonwoven fabric according to claim 21, wherein the entanglement of the fibers is performed by a water flow.   The method for producing a nonwoven fabric according to claim 21, wherein the fibers are joined by heat fusion.   The manufacturing method of the nonwoven fabric of Claim 21 which joins a fiber with an adhesive component.