JP4742673B2 - Cellulosic artificial leather - Google Patents

Description

  The present invention relates to an artificial leather using cellulosic ultrafine fibers. More specifically, the present invention relates to an artificial leather having a fiber entangled body including cellulosic ultrafine fibers and a polymer elastic body as main components, and has high hygroscopicity and soft texture.

  Artificial leather that has a texture similar to that of natural leather has been studied for a long time. In general, fiber entanglements made of polyamide fibers or polyester fibers are the main type of artificial leather. It has been used as a constituent.

  Artificial leather using extra fine fibers of polyamide fiber has a good characteristic that the texture is flexible because of its low Young's modulus, but because the texture of the artificial leather inevitably exhibits the unique slimness of nylon, it is high quality There was a disadvantage that natural leather-like texture was not obtained. On the other hand, artificial leather using ultrafine polyester fibers has a dull touch as compared with nylon-based artificial leather, but has a drawback that it tends to be inferior in flexibility due to its high Young's modulus. In addition, when the fineness of the single yarn is made extremely fine in order to express flexibility, it is difficult to dye artificial fibers with good coloring properties, and the polyester fiber has absolutely no moisture absorption / release properties. As a result, artificial leather also has the drawback of being easily charged with static electricity.

  For the purpose of improving the color developability of the polyester-based artificial leather, a technique using an aliphatic polyester fiber such as polylactic acid as a fiber constituting the fiber entanglement is known [see Patent Document 1]. In this case, although the color developability is certainly better than that of aromatic polyester-based artificial leather, moisture absorption and release is not improved at all even by using aliphatic polyester, and artificial leather is easily charged with static electricity. The disadvantage of this was not solved. In addition, since aliphatic polyester fibers generally have a high hydrolysis rate, conditions such as dyeing process are restricted, and as a result, there is a problem that process passability in various high-level fabric processing is low.

  In addition, a technique using polypropylene terephthalate bimetallic composite fiber instead of polyethylene terephthalate is known for the purpose of improving the flexibility and writing performance of polyester-based artificial leather [see Patent Document 2]. In this case as well, since the fibers have almost no moisture absorption and desorption property, the artificial leather has a drawback that it is easily charged with static electricity. Polypropylene terephthalate can be dyed at low temperatures, but the color sharpness and darkness are not significantly different from those of polyethylene terephthalate, and the color developability is generally poor.

On the other hand, for an artificial leather-like fiber structure using cellulosic fibers, a flocked product in which cellulosic fiber flocs are planted has been proposed [see Patent Document 3]. This flock is obtained by flocking a base fabric using a conventional rayon fiber or the like, and examples show floc thicknesses of 0.8 denier (0.88 dtex) to 2.0 denier (2.2 dtex). ing. Since the fineness of the cellulosic fiber is large, there is a problem that the softness of the texture is not sufficient and the operation of flocking is required.
JP 2002-54077 A JP 2003-286663 A JP-A-5-25769

  The problem of the present invention is the problem of conventional artificial leather using polyamide-based and polyester-based ultrafine fibers by using cellulose-based ultrafine fibers as the ultrafine fibers constituting the fiber entanglement that is a constituent of artificial leather. Is to solve the problem drastically and to provide an artificial leather with extremely excellent hygroscopicity.

An object of the present invention described above is that, in an artificial leather mainly composed of a fiber entanglement including ultrafine fibers having a single yarn fineness of 0.5 dtex or less and a polymer elastic body, at least a part of the ultrafine fibers is cellulose. Tona is, microfibers, after producing the cellulose ester fibers, fibers obtained by a hydroxyl group was regenerated by hydrolyzing the ester bond, to produce a composite fiber comprising a cellulose ester and another polymer component, other This can be solved by a cellulose-based artificial leather, which is selected from fibers obtained by regenerating hydroxyl groups by removing the polymer component and hydrolyzing the cellulose ester . Here, it can be suitably employed that the polymer elastic body is polyurethane. Moreover, it is possible to suitably employ a moisture absorption difference (ΔMR) represented by a difference between a moisture absorption rate at 30 ° C. × 90% RH and a moisture absorption rate at 20 ° C. × 65% RH is 3 to 10%.

  According to the present invention, an artificial leather having a touch similar to that of natural leather and having extremely good moisture absorption performance can be obtained. Since this artificial leather is excellent in flexible touch, it can be suitably used as an outer layer of furniture and a vehicle interior material as well as clothing.

  The artificial fiber of the present invention is mainly composed of a fiber entangled body of ultrafine fibers having a single yarn fineness of 0.5 dtex or less and a polymer elastic body. The ultrafine fibers having a single yarn fineness of 0.5 dtex or less are It is important that at least a part thereof is made of cellulose. Here, that at least a part is cellulose means that, for example, a composite fiber such as a surface layer portion of a fiber is cellulose and an inner phase portion is a cellulose ester is also included.

  In order to realize the flexibility of artificial leather and the leather-like surface touch, it is preferable that the single yarn fineness of the cellulose fiber is thinner. Specifically, it is more preferably 0.4 dtex or less, and most preferably 0.3 dtex or less. When the single yarn fineness is larger than 0.5 dtex, there is no change from the conventional fiber structure using rayon fiber as a flock, which may cause the texture of artificial leather to be hardened and the denseness to be lowered. .

  The cellulose fiber of the present invention preferably has a fiber strength of 1.2 cN / dtex or more. A strength of 1.2 cN / dtex or more is preferred because defects such as fibrillation are unlikely to occur and product durability is increased. The strength of the cellulose ester fiber is more preferably 1.3 cN / dtex or more, and most preferably 1.5 cN / dtex or more.

  The cross-sectional shape of the cellulose fiber is not particularly limited and may be a perfect circular circular cross-section, and may be a multilobal shape, flat shape, elliptical shape, W shape, S shape, X shape, H shape, C Different cross-section yarns such as a letter shape, a square shape, a cross-girder shape and a hollow shape may be used.

  Cellulose fibers in the present invention, if necessary, for additives such as plasticizers, lubricants, antistatic agents, dyes, pigments, ultraviolet absorbers, antibacterial agents, lubricants, matting agents, biodegradation accelerators, These can be contained alone or in combination.

  The ultrafine cellulose fiber of the present invention may be obtained by direct spinning, or may be a fiber obtained by regenerating hydroxyl groups by hydrolyzing ester bonds after producing cellulose ester fibers. Good. In order to obtain a cellulose fiber having the finest possible fineness, for example, a composite fiber composed of a cellulose ester and another polymer component is produced, and the other polymer component is removed and the cellulose ester is hydrolyzed. The obtained cellulose fiber may be sufficient.

  In order to obtain the cellulose fiber used in the present invention, when a composite fiber comprising a cellulose ester and other components is used, the composite component includes polystyrene, polyolefin, polyamide, polyester, polylactic acid, and sulfoisophthalic acid. Polymerized hot water soluble polyester, polyvinyl alcohol, polyethylene glycol and the like can be used, but are not limited thereto. In particular, when hot water-soluble polyester and polylactic acid are used, cellulose ester ultrafine fibers can be generated by alkali hydrolysis treatment, and celluloseization proceeds by hydrolysis of the cellulose ester, which can be preferably employed. .

  In the present invention, the fiber entangled body can be formed by forming a web using a card web forming method or a paper making method as usual, and then performing needle punching, water jet punching, or a combination thereof. . In order to strengthen the fiber entangled body, a separately prepared woven fabric or knitted fabric may be entangled and integrated with the entangled body.

  In this case, the yarn type constituting the woven fabric or the knitted fabric can be a filament, a spun yarn, a blended yarn of a filament and a staple, and the like, and is not particularly limited. These fibers can be twisted. When a twisted yarn having a twist number of 500 T / m or more is used, it is preferable because fiber damage is reduced when punching with a needle punch or the like. The structure of the woven fabric or the knitted fabric is not particularly limited, and plain weave, twill weave, satin weave or a change weave thereof, warp knitting, weft knitting, lace knitting or a change knitting thereof can be suitably employed.

  The artificial leather of the present invention has a polymer elastic body as a constituent component. Specific examples of the polymer elastic body include polyurethane elastomer, acrylonitrile-butadiene elastomer, butadiene elastomer, natural rubber, soft polyvinyl chloride elastomer, polyester ether elastomer, polyether ester amide elastomer, polyether amide elastomer, and the like. It is not limited to these. Of these, polyurethane elastomers are preferred from the viewpoint of processability and product quality.

  The polymer elastic body in the artificial leather of the present invention is preferably 10 to 75% by weight based on the whole artificial leather. When the weight of the polymer elastic body is too large, the surface touch of the artificial leather may be deteriorated or the color fastness may be deteriorated. On the other hand, if the weight of the polymer elastic body is too small, the fiber entanglement may be easily unwound and the product life may be shortened. The weight of the polymer elastic body is more preferably 15 to 70% by weight, and most preferably 20 to 60% by weight with respect to the whole artificial leather. These polymer elastic bodies may be blended with additives such as a colorant, an antioxidant, an antistatic agent, a dispersant, a softening agent, and a coagulation adjusting agent as necessary.

  About the sheet | seat after assign | providing a polymeric elastic body, it is preferable to carry out raising treatment of at least one surface, and to form a fiber raised surface. Various methods such as buffing with sandpaper or the like can be used as a method for forming the fiber raised surface. When the fiber entangled body is entangled and integrated with the woven fabric or knitted fabric, it is preferable to raise the entangled surface of the ultrafine fiber, and when the woven fabric or knitted fabric is near the surface layer, It can also be lightly scratched to such an extent that the knitted fabric is not damaged.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, about the tensile strength, the moisture absorption difference ((DELTA) MR), the softness | texture softness, coloring property, and napping, it measured and evaluated by the following method.

(1) Tensile strength Tensilon UCT-100 type manufactured by Orientec Co., Ltd. was used to conduct a tensile test under the conditions of a sample length of 5 mm and a tensile speed of 20 mm / min, and the stress when the sample was cut was determined as the tensile strength (cN / dtex).

(2) Moisture absorption difference (△ MR)
About 1 g of artificial leather used as a sample was cut out, and the weight (W ₀ ) when completely dried was measured. This sample was allowed to stand for 24 hours in constant temperature and humidity (LH-20-11M manufactured by Nagano Kagaku Kikai) adjusted to a temperature of 20 ° C. and 65% RH, and the weight (W ₂₀ ) of the sample in an equilibrium state was measured. Then, after changing to a state of 30 ° C. × 90% RH and allowing to stand for 24 hours, the weight (W ₃₀ ) of the sample in an equilibrium state was measured. It calculated | required by the following formula.

Moisture absorption difference (ΔMR) (%) = {(W ₃₀ −W ₂₀ ) / W ₀ } × 100
(3) Texture softness, color development, napped hair evaluation Each characteristic was evaluated by sensory evaluation using artificial leather as a sample. The evaluation results were evaluated as “◯” when the artificial leather was superior, “Δ” when it was excellent, “Δ” when it was within the allowable range, and “X” when it was clearly inferior.

Example 1
Cellulose Acetate Propionate (CAP482-20 manufactured by Eastman Chemical Co., Ltd.) 90 wt% and polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., PEG 600) 10 wt% as a plasticizer are mixed using a 30 mmφ extruder to prepare a cellulose ester composition. A product pellet was obtained.

  This cellulose ester composition was used as an island component, polylactic acid was used as a sea component, and a sea-island type composite die having 16 islands was spun at a sea / island ratio of 30/70% by weight. After cooling with a chimney wind, the oil agent was applied and focused, and then taken up by a godet roller rotating at 1000 m / min.

  The obtained fiber was subjected to mechanical crimping with a stuffer box using a staple drawing machine with a draw ratio of 1.0, and then cut to a fiber length of 51 mm. The number of crimps was an appropriate level of 10 peaks / 25 mm. The thickness of the single fiber was 11 dtex.

  This raw cotton was made into a web with a card and a cross wrapper, and then needle punched to prepare a nonwoven fabric sheet. Next, this sheet was immersed in a 3% aqueous sodium hydroxide solution at 95 ° C., and repeated pressing with a mangle removed sea components and hydrolyzed the cellulose ester. The nonwoven fabric sheet after the treatment became cellulose fibers having a single yarn fineness of about 0.3 dtex.

  Subsequently, the emulsion polyurethane was impregnated with respect to the whole artificial leather so as to give an amount of 50% by weight and dried, followed by heat setting. The sheet was brushed with a buffing machine using sandpaper, then charged into a circular dyeing machine and dyed brown at a dyeing temperature of 100 ° C.

  Table 1 shows the properties of the obtained artificial leather. The difference in moisture absorption rate (ΔMR) was 5.1%, indicating good moisture absorption / release properties. Since the single yarn fineness of cellulose was sufficiently thin at 0.3 dtex, the softness of the texture was excellent.

Examples 2-4
An artificial leather was produced in the same manner as in Example 1 except that the fineness of the single yarn was 0.2 dtex in Example 2, 0.1 dtex in Example 3, and 0.5 dtex in Example 4.

  Table 1 shows the properties of the obtained artificial leather. In Example 4 where the single yarn fineness was 0.5 dtex, a slightly inferior point in the softness of the texture was observed, but it was within an acceptable range. In all examples, the difference in moisture absorption rate (ΔMR) was 5.1%, and the moisture absorption performance was extremely excellent.

Comparative Example 1
Thirty commercially available cellulose diacetate fibers (84 dtex-20 fil) obtained by dry spinning using acetone as a solvent are aligned to form 2520 dtex-600 fil sub-tow, and further 38 sub-tow are aligned to 95760 dtex-22800 dtex (single yarn A tow having a fineness of 4.2 dtex). The obtained tow was subjected to mechanical crimping with a stuffer box using a staple drawing machine with a draw ratio of 1.0, and then cut to a fiber length of 51 mm. An artificial leather was produced in the same manner as in Example 1 except that the obtained short fiber was used as a raw material for the fiber entangled body.

  The properties of the obtained sheet are shown in Table 2, and the artificial leather was inferior in texture flexibility because the single yarn fineness was too thick at 4.2 dtex. Moreover, the moisture absorption difference was inferior at 2.8%.

Comparative Example 2
An artificial leather was produced in the same manner as in Example 1 except that polyethylene terephthalate was used as the island component and the single yarn fineness of the island was 0.02 dtex.

  The properties of the obtained artificial leather are shown in Table 2. Since the constituent fiber is polyester, the difference in moisture absorption was only 0.2%, and the moisture absorption / release property was inferior.

Claims (4)

A fiber-entangled body fineness comprises the following ultrafine fibers 0.5 dtex, in the artificial leather of the elastic polymer as a main component state, and are not at least a portion of the ultrafine fibers made of cellulose, microfine After the cellulose ester fiber is produced, the fiber is obtained by regenerating hydroxyl groups by hydrolyzing the ester bond, and the composite fiber composed of cellulose ester and other polymer components is produced, and the other polymer components are removed. together, cellulosic artificial leather, characterized in der Rukoto those selected from fibers obtained by a hydroxyl group was regenerated by carrying out the hydrolysis of the cellulose ester. The cellulosic artificial leather according to claim 1, wherein the polymer elastic body is polyurethane. 3. A moisture absorption difference (ΔMR) expressed by a difference between a moisture absorption rate at 30 ° C. × 90% RH and a moisture absorption rate at 20 ° C. × 65% RH is 3 to 10%. Cellulosic artificial leather according to Item. The cellulose-based artificial leather according to any one of claims 1 to 3, wherein the cellulose ester is cellulose acetate propionate.