Method for manufacturing nonwoven fabric products using processed nonwoven fabric

Abstract

To provide a method for producing a nonwoven fabric product from nonwoven fabric that allows the texture or touch of the nonwoven fabric product to be improved when the product is used, and improves the processability when the product is produced.SOLUTION: A nonwoven fabric containing a thermoplastic resin and a lubricant is heat treated at a temperature that is equal to or higher than the crystallization temperature of the thermoplastic resin and equal to or lower than the melting point of the thermoplastic resin, and then processed into a nonwoven fabric product.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a nonwoven fabric product, and more particularly to a method for producing a nonwoven fabric product using a nonwoven fabric containing a thermoplastic resin and a lubricant. [Background technology]

[0002] Conventionally, nonwoven fabrics have been used for various purposes such as disposable diapers, sanitary products, other sanitary products, clothing materials, bandages, packaging materials, etc. As such, nonwoven fabrics are often used for purposes in which they come into direct contact with the body, and from the viewpoint of a good fit and comfort to the body, improvements in the feel and texture are required, and various technical developments have been made so far. For example, nonwoven fabrics constituting disposable diapers and the like are in direct contact with the skin of, for example, infants and young children, and therefore must be particularly flexible and comfortable to the touch.

[0003] One method for improving the texture, such as the feel to the touch, of a nonwoven fabric is to add an additive such as a lubricant to the nonwoven fabric, which improves the feel to the touch and texture of the nonwoven fabric by causing the added lubricant to bleed onto the surface of the nonwoven fabric (see, for example, Patent Documents 1 and 2).

[0004] On the other hand, additives such as surfactants may bleed out during melt spinning (see Patent Document 3), and excessive bleeding of additives may reduce processability during the manufacturing process, such as making it difficult to hold the product during packaging and other processes due to the bleed-out additives. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-38364 A [Patent Document 2] International Publication No. 2012 / 105567 [Patent Document 3] JP 2018-178278 A Summary of the Invention [Problem to be solved by the invention]

[0006] In view of these circumstances, an object of the present invention is to provide a method for producing a nonwoven fabric product using a nonwoven fabric that improves the texture, such as the feel of the nonwoven fabric product, when the product is in use, while suppressing excessive bleeding during product production and improving processability. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following aspects.

[0008] One embodiment of the present invention relates to a method for producing a nonwoven fabric product, in which a nonwoven fabric containing a thermoplastic resin and a lubricant is heat-treated at a temperature equal to or higher than the crystallization temperature and lower than the melting point of the thermoplastic resin, and then processed to produce a nonwoven fabric product.

[0009] In one embodiment of the present invention, the melting point of the thermoplastic resin may be 100°C or higher, and in another embodiment, the lubricant may be a fatty acid amide having 15 to 22 carbon atoms, and the nonwoven fabric may contain the lubricant in an amount of 3,000 to 6,000 ppm.

[0010] In one embodiment of the present invention, the processing may be carried out in a state in which the amount of bleed-out lubricant after the heat treatment of the nonwoven fabric is less than 60% of the amount of lubricant contained in the nonwoven fabric, and in another embodiment, the processing may be carried out within 3 hours after the heat treatment.

[0011] In one embodiment of the present invention, the nonwoven fabric is produced by a spunbond process, in another embodiment, the thermoplastic resin may be a polypropylene-based resin, and in one embodiment, the lubricant may be erucamide.

[0012] In one embodiment of the present invention, the heat treatment is carried out by maintaining the temperature at 56 to 70° C. for 3 hours or more. In another embodiment, the processing is carried out after cooling to room temperature after the heat treatment. Effect of the Invention

[0013] The method for producing a nonwoven fabric product of the present invention can produce a nonwoven fabric that has the texture, such as the feel of a nonwoven fabric product, when the product is in use, but has improved processability when the product is produced. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a simulation of the bleeding of a lubricant from a polypropylene resin during the process from nonwoven fabric manufacturing to product processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described, however, the present invention is not limited to the following embodiment.

[0016] A.Nonwoven fabric The nonwoven fabric processed in the present invention is produced from a resin composition containing a thermoplastic resin and a lubricant.

[0017] A-1. Thermoplastic resin The thermoplastic resin used in the present invention may be any resin compatible with the lubricant described below, and is preferably a thermoplastic resin having a melting point of 100° C. or higher. Specifically, polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polytrimethylene terephthalate; polyimide resins; polyamide resins such as nylon 6,6, and copolymers and mixtures thereof may be used. The thermoplastic resin of the present invention may be a mixture of two or more resins having different crystallinity.

[0018] In one embodiment of the present invention, the thermoplastic resin may be an olefin-based resin. The olefin-based resin that can be used in the present invention is preferably an olefin-based polymer obtained by polymerizing at least one monomer selected from ethylene and an α-olefin having 3 to 28 carbon atoms. In particular, a polypropylene resin is preferable. The olefin-based resin used in the present invention may be a mixture of a low-crystalline resin having a low melting point and a high-crystalline resin having a high melting point.

[0019] The molecular weight of the thermoplastic resin used in the present invention varies depending on the monomers and melting points used. In one embodiment of the present invention, a polypropylene resin preferably has a weight average molecular weight of 100,000 to 200,000.

[0020] A-2. Lubricants The lubricant used in the present invention is not particularly limited as long as it is compatible with the above-mentioned thermoplastic resin and partially bleeds out on the fiber surface at the product use temperature.For example, fatty acid amide compounds; fatty acid compounds; paraffin and hydrocarbon resins; silicone compounds; silicone polymers; fluorine compounds, fluorine polymers such as copolymers of tetrafluoroethylene and propylene, copolymers of vinylidene fluoride and hexafluoropropylene, and mixtures thereof can be used.In one embodiment of the present invention, the lubricant is preferably a fatty acid amide compound.

[0021] Examples of the fatty acid amide compound include fatty acid monoamide compounds, fatty acid diamide compounds, saturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds. Fatty acid amides having 15 to 22 carbon atoms are preferred. Specific examples include lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, montanic acid amide, N,N'-methylene-bis-lauric acid amide, N,N'-methylene-bis-myristic acid amide, N,N'-methylene-bis-palmitic acid amide, N,N'-methylene-bis-behenic acid amide, N,N'-methylene-bis-oleic acid amide, N,N'-methylene-bis-erucic acid amide, N,N'-ethylene-bis-oleic acid amide, and N,N'-ethylene-bis-erucic acid amide, and these may be used in combination. Erucic acid amide is particularly preferred.

[0022] The content of the lubricant in the present invention is not particularly limited and is, for example, in the range of 0.01 to 1 mass %, preferably 0.1 to 0.6 mass % in the resin composition. This content is determined by comprehensively judging the type of thermoplastic resin, resin properties such as crystallinity and MFR, type of lubricant, required properties of the obtained nonwoven fabric, heat treatment conditions, etc.

[0023] For example, when polypropylene resin is used as the thermoplastic resin and erucic acid amide is used as the lubricant, the range of 800 to 8000 ppm, particularly 3000 to 6000 ppm, relative to the resin composition is preferred. In this case, depending on the processing conditions, if the amount is less than 800 ppm, it may be difficult to control the static friction coefficient of the nonwoven fabric to a range of 0.1 to 0.4, whereas if the amount exceeds 8000 ppm, the amount of erucic acid amide on the surface of the nonwoven fabric increases, which may cause deterioration of the appearance such as generation of white powder, and deterioration of heat fusion property and secondary processability.

[0024] A-3. Other additives To the nonwoven fabric processed in the present invention, known additive components generally used for nonwoven fabrics can be added for the purpose of the nonwoven fabric product, for imparting properties, etc., so long as they do not affect the properties of the nonwoven fabric during processing after the heat treatment described below. These known additive components include neutralizing agents such as calcium stearate and hydrotalcite, antioxidants such as phenolic, phosphorus-based and sulfur-based antioxidants, heat stabilizers, nucleating agents, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, pigments, dyes, and inorganic powders such as silica, talc, calcium carbonate, calcium oxide and magnesium oxide.

[0025] B. Manufacturing method of nonwoven fabric for processing B-1. Manufacturing of untreated nonwoven fabric The nonwoven fabric processed in the present invention may be manufactured using either long or short fibers formed from a resin composition containing the above-mentioned thermoplastic resin and lubricant. A known method can be adopted as a method for obtaining a nonwoven fabric. For example, the spunbond method, meltblown method, spunlace method, thermal bond method, chemical bond method, airlaid method, needle punch method, flash spinning method, etc. are mentioned. In one embodiment of the present invention, the meltblown method or the spunbond method is preferred, and the spunbond method is more preferred.

[0026] B-2. Heat treatment of nonwoven fabric (aging treatment) In one embodiment of the present invention, the nonwoven fabric produced by the above method may be subjected to a heat treatment (aging treatment) before processing. The heat treatment is performed at a temperature at which the diffusion of the lubricant in the thermoplastic resin is promoted, and is preferably performed at a temperature below the melting point of the thermoplastic resin and above room temperature. In addition, the heat treatment temperature in one embodiment of the present invention may be determined based on the combination of the thermoplastic resin and the lubricant. For example, when a polypropylene-based resin is used as the thermoplastic resin, the heat treatment may be performed at 56°C to 70°C.

[0027] In one embodiment of the present invention, the heat treatment is performed for a time sufficient for at least a part of the bleed-out lubricant to dissolve in the fibers. For example, the heat treatment may be performed by holding the nonwoven fabric at a temperature of 56°C to 70°C for 3 hours or more.

[0028] The heat treatment makes the lubricant compatible with the thermoplastic resin, so that the lubricant that has bled out onto the fiber surface dissolves into the fiber, and the friction coefficient of the fiber surface increases. C. Nonwoven fabric processing In one embodiment of the present invention, the heat-treated nonwoven fabric is processed to produce a nonwoven fabric product. After heat treatment, the nonwoven fabric may be directly subjected to processing, or may be cooled to an appropriate temperature, such as room temperature, and then processed.

[0029] After cooling, the lubricant that was compatible in the fibers starts to bleed out again to the fiber surface, so it is preferable to carry out the above processing from the heat treatment as soon as possible. In one embodiment of the present invention, it is preferable to carry out the processing before 63% of the lubricant contained in the nonwoven fabric fibers bleeds out. For example, in one embodiment of the present invention, the processing is carried out within 3 hours at room temperature after the heat treatment. The heat treatment increases the friction coefficient of the fiber surface, making the nonwoven fabric easier to grip, and improving workability in the movement and packaging of nonwoven fabrics and nonwoven fabric products. In addition, by carrying out the heat treatment, the amount of lubricant that bleeds out to the fiber surface can be kept constant without being affected by the manufacturing environment of the nonwoven fabric, such as the manufacturing temperature, so that the adjustment of the processing machine is easy. On the other hand, when a consumer or the like uses the product, a long time has passed since the heat treatment for the lubricant that was compatible in the fibers to bleed out to the fiber surface, so the texture of the nonwoven fabric brought about by the lubricant is not impaired.

[0030] The nonwoven fabric products produced by the method of the present invention are not particularly limited, but include, for example, materials for disposable diapers, elastic materials for diaper covers, elastic materials for sanitary products, elastic materials for sanitary products, elastic tapes, bandages, elastic materials for clothing, insulating materials for clothing, heat-retaining materials for clothing, protective clothing, hats, masks, gloves, supports, elastic bandages, base fabrics for poultices, anti-slip base fabrics, vibration absorbing materials, finger cots, air filters for clean rooms, electret filters that have been subjected to electret processing, and ceramics. Examples of the material include paratars, heat insulating materials, coffee bags, food packaging materials, automobile ceiling covering materials, soundproofing materials, cushioning materials, speaker dustproofing materials, air cleaner materials, insulator coverings, backing materials, adhesive nonwoven fabric sheets, various automobile parts such as door trims, various cleaning materials such as cleaning materials for copiers, carpet coverings and backing materials, agricultural wrappings, wood drains, shoe parts such as sports shoe coverings, bag parts, industrial sealing materials, wiping materials, sheets, etc. In particular, one embodiment of the present invention is preferably used in the production of sanitary products such as disposable diapers. EXAMPLES

[0031] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0032] [Measurement of the amount of bleed-out lubricant] A 1 g sample of the nonwoven fabric was taken, and the lubricant that had bled onto the surface was dissolved with methanol. The amount of lubricant in the solvent was then quantitatively analyzed by GC-MS to measure the amount of bleed.

[0033] [Measurement of the coefficient of friction of nonwoven fabric] In accordance with JIS K7125, a HEIDON surface property tester (14DR: manufactured by Shinto Scientific Co., Ltd.) was used to measure the dynamic friction coefficient at five points with two nonwoven fabrics in contact with each other, a contact surface area of ​​40 cm2, a load of 200 g, and a speed of 100 mm / min. The average value was taken as the friction coefficient.

[0034] [Example 1: Production of nonwoven fabric 1] (Nonwoven fabric manufacturing) 90 parts of polypropylene resin (melting point 162°C, MFR 60g / 10min) and 8 parts of a master batch prepared by mixing polypropylene resin (melting point 162°C, MFR 60g / 10min) with 5% by weight of erucic acid amide were mixed in a metering mixer in a resin pellet hopper installed upstream of the raw material charging position in a kneading extruder (manufactured by Japan Steel Works, Ltd., single-screw kneading extruder (diameter φ40mm)).

[0035] In the kneading extruder, the screw rotation speed was adjusted so that the extrusion rate was 100 to 200 kg / hour, and the molten resin was produced and introduced into a die equipped with a large number of spinning holes (nozzles) and discharged. The melt-spun long fibers were then introduced into a cooling chamber, cooled by cooling air, and then stretched (pulled) by stretching air, and the long fiber aggregate was deposited on a moving collection surface. The deposited long fiber aggregate was partially heat-sealed by an embossing roll to form a spunbonded nonwoven fabric. The obtained nonwoven fabric was wound up by a winder and divided into widths of 500 mm by a slitter to prepare a nonwoven fabric roll with a winding length of 10,000 m, and the both ends were covered with craft paper and packaged in polyethylene film by an automatic packaging machine. In the packaged state, it was stored in a warehouse at room temperature of 30 ° C for 24 hours. The amount of erucic acid amide bleeding in the nonwoven fabric after storage was measured.

[0036] (Heat treatment) After storage, the nonwoven fabric was packaged and subjected to a heat treatment for 3 hours in a thermostatic chamber at 60° C. The amount of erucamide bleeding after the heat treatment was measured.

[0037] (Product processing) The nonwoven fabric removed from the thermostatic chamber was attached to the processing machine and processed into a product. The processing time was 3 hours. The amount of erucic acid amide bleeding and the friction coefficient of the nonwoven fabric sampled from the processed product were measured.

[0038] [Example 2: Production of nonwoven fabric 2] The amount of erucamide bleeding and the friction coefficient of the nonwoven fabric were measured in the same manner as in Example 1, except that the heat treatment temperature was set to 56° C. in the (heat treatment) step.

[0039] [Comparative Example 1: Production of nonwoven fabric A1] The amount of erucamide bleeding and the friction coefficient of the nonwoven fabric were measured in the same manner as in Example 1, except that the (heat treatment) step was not performed.

[0040] [Comparative Example 2: Production of nonwoven fabric A2] The amount of erucamide bleed and the friction coefficient of the nonwoven fabric were measured in the same manner as in Example 1, except that the heat treatment temperature was 40° C. in the (heat treatment) step.

[0041] [Table 1]

[0042] FIG. 1 is a diagram illustrating the bleeding of lubricant from polypropylene resin during the nonwoven fabric manufacturing and processing processes.

[0043] In this example, a bleed-out amount of 2500 ppm or more is required for the product, but in order to prevent slippage problems during product processing, it is required that the amount be 2500 ppm or less within the processing time.

[0044] In Examples 1 and 2, the concentration was 2500 ppm or less during processing, and was 2500 ppm or more after processing.

[0045] In Comparative Examples 1 and 2, the content is 2500 ppm or more during processing, causing slip problems. In Comparative Example 2, when heat treatment is performed at 40°C, the amount of bleeding increases. This is because the amount of erucamide remaining in the resin is greater than the amount of erucamide that is saturated and dissolved in the resin at 40°C, and therefore increasing the temperature to 40°C accelerates diffusion and causes bleeding to progress more quickly.

Claims

1. A nonwoven fabric containing a thermoplastic resin and a lubricant is heat-treated at a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point of the thermoplastic resin, and then processed to produce a nonwoven fabric product; The thermoplastic resin is a polypropylene-based resin, The lubricant is erucamide, The method for producing a nonwoven fabric product is characterized in that the heat treatment is carried out by maintaining the temperature at 56 to 70° C. for 3 hours or more.

2. 2. The method according to claim 1, wherein the melting point of the thermoplastic resin is 100° C. or higher.

3. A manufacturing method as described in claim 1 or 2, characterized in that the nonwoven fabric contains 3,000 to 6,000 ppm of the lubricant.

4. The method according to any one of claims 1 to 3, characterized in that the processing is performed such that an amount of the lubricant bleed-out after the heat treatment of the nonwoven fabric is less than 63% of the amount of the lubricant contained in the nonwoven fabric.

5. The method according to any one of claims 1 to 4, wherein the processing is carried out within 3 hours after the heat treatment.

6. The method according to any one of claims 1 to 5, wherein the nonwoven fabric is produced by a spunbond method.

7. The method according to any one of claims 1 to 6, wherein the processing is carried out after the heat treatment and cooling to room temperature.

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