JP4661345B2 - Cellulose ester artificial leather - Google Patents

Description

  The present invention relates to an artificial leather using cellulose ester-based ultrafine fibers. More specifically, the present invention relates to an artificial leather mainly composed of a fiber entangled body including a cellulose ester-based ultrafine fiber and a polymer elastic body, and has high coloring property, soft texture, and moisture absorption / release properties.

  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 ultra-fine fibers of polyamide fiber has a good characteristic that the texture is flexible due to its low Young's modulus, but because the texture of the artificial leather inevitably exhibits a slimy feeling unique to nylon, 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.

On the other hand, a technique using polypropylene terephthalate bimetal composite fiber instead of polyethylene terephthalate is known for the purpose of improving the flexibility and writing performance of polyester 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.
JP 2002-54077 A JP 2003-286663 A

  An object of the present invention is to provide a conventional artificial leather using polyamide-based and polyester-based ultrafine fibers by mainly using cellulose ester-based ultrafine fibers as the ultrafine fibers constituting the fiber entanglement that is a constituent of artificial leather. It is an object of the present invention to provide a high-quality artificial leather excellent in flexibility, color development, and moisture absorption / release properties.

The above-mentioned problem of the present invention is composed of at least one selected from cellulose acetate propionate and cellulose acetate butyrate, and a fiber entanglement composed mainly of cellulose ester fibers having a single yarn fineness of 0.5 dtex or less, This can be solved by a cellulose ester-based artificial leather mainly composed of a polymer elastic body .

  The cellulose ester fiber preferably has a strength of 1.2 cN / dtex or more. On the other hand, the polymer elastic body may be a polyurethane elastic body. The artificial leather of the present invention has a moisture absorption difference (ΔMR) of 0.5 to 3% 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 preferred.

  According to the present invention, an artificial leather having a touch similar to that of natural leather and having both a very soft texture and color developability can be obtained. Since this artificial leather is also excellent in moisture absorption and desorption, it is suitable for use as a clothing exterior or vehicle interior material, as well as for clothing.

The artificial fiber of the invention is mainly composed of a fiber entangled body and a polymer elastic body, and the fiber entangled body is mainly composed of cellulose ester fibers having a single yarn fineness of 0.5 dtex or less. . In order to realize the flexibility of the artificial leather and the leather-like surface touch, it is preferable that the single yarn fineness of the cellulose ester fiber is as thin as possible. Specifically , 0 . Most preferably, it is 3 dtex or less. When the single yarn fineness is larger than 0.5 dtex, even if a soft cellulose ester fiber is used, it may undesirably cause a texture hardening of the artificial leather, a decrease in denseness, or the like. For example, cellulose ester filaments having a single yarn fineness of 2.2 dtex or more used for general woven or knitted fabrics and cellulose ester staples having a fineness of 2.2 dtex or more used for general cigarette filters are not suitable for the present invention.

  In the present invention, the cellulose ester fiber means one in which at least a part of the hydroxyl group of cellulose is substituted with an acyl group by an ester bond. The most common cellulose ester is cellulose acetate having an acyl group having 2 carbon atoms. Examples of cellulose acetate include cellulose triacetate having a substitution degree of 2.9 or more and a substitution degree of 2.4 to 2.6. Specific examples include cellulose diacetate and cellulose acetate having a substitution degree other than those described above.

In the present invention, it is preferable that at least a part of the acyl group of the cellulose ester has 3 or more carbon atoms, and at least one selected from cellulose acetate propionate and cellulose acetate butyrate is used. . When a cellulose ester having a propionyl group which is an acyl group having 3 carbon atoms is used, an artificial leather having higher flexibility than that of cellulose acetate having only an acetyl group having 2 carbon atoms is obtained. When a cellulose ester having a butyryl group which is an acyl group is used, an artificial leather with higher flexibility can be obtained.

  The ultrafine fiber of the present invention may be obtained by direct spinning, or may be obtained by a method of removing at least one component from the ultrafine fiber-generating fiber or peeling each component. There may be. In order to obtain the cellulose ester fiber of the present invention, when a composite fiber with a component other than the cellulose ester is used as the ultrafine fiber-generating fiber, the composite component is particularly limited as long as the ultrafine fiber can be generated. Can be used without. Specific examples include polystyrene, polyolefin, polyamide, polyester, polylactic acid, sulfoisophthalic acid copolymer hot water-soluble polyester, polyvinyl alcohol, polyethylene glycol and the like, but are not limited thereto. Among these, when hot water-soluble polyester, polyvinyl alcohol, or polyethylene glycol is used, cellulose ester ultrafine fibers can be generated by hot water treatment, and the characteristics of the cellulose ester fibers can be preferably used.

  The cellulose ester 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 ester 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, A deformed cross-sectional yarn such as a C-shape, a U-shape, a cross-beam shape, and a hollow shape may be used.

  The cellulose ester fiber in this invention can contain the stabilizer for coloring prevention as needed. A phosphite compound, a hindered phenol compound, etc. can be used for a coloring inhibitor. In addition, other additives such as plasticizers, lubricants, antistatic agents, dyes, pigments, ultraviolet absorbers, antibacterial agents, lubricants, matting agents, biodegradation accelerators, etc. are contained alone or in combination. can do.

  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.
(Synthesis Example 1)
Acetic acid 5.0 kg and propionic acid 1.0 kg were added to cellulose (Nippon Paper Chemical Co., Ltd. dissolving pulp, NDP-S) 1.0 kg, and stirred at 50 ° C. for 30 minutes. After the mixture was cooled to 15 ° C., 0.7 kg of acetic anhydride, 4.3 kg of propionic anhydride and 0.05 kg of sulfuric acid were added to carry out an esterification reaction. After stirring for 240 minutes, a mixed solution of 3.3 kg of acetic acid and 1.7 kg of water was added over 60 minutes to stop the reaction. Subsequently, stirring was continued at 40 ° C. for 24 hours to perform a hydrolysis treatment.

  Thereafter, a large excess of water was added to the dope to precipitate cellulose acetate propionate. The precipitated powder was filtered, washed with water and filtered repeatedly 5 times, further treated in 0.02% dilute sulfuric acid at 50 ° C. for 1 hour, washed with water and filtered 3 times.

The cellulose acetate propionate obtained had an acetyl substitution degree of 0.3 and a propionyl substitution degree of 2.5. This cellulose acetate propionate is designated as CAP1.
(Synthesis Example 2)
4.0 kg of acetic acid and 2.0 kg of propionic acid were added to 1.0 kg of cellulose (dissolved pulp manufactured by Nippon Paper Chemicals Co., Ltd., NDP-S), and mixed at 50 ° C. for 30 minutes. After the mixture was cooled to 15 ° C., 2.0 kg of acetic anhydride, 3.0 kg of propionic anhydride, and 0.05 kg of sulfuric acid were added to carry out an esterification reaction. After stirring for 240 minutes, a mixed solution of 3.3 kg of acetic acid and 1.7 kg of water was added over 60 minutes to stop the reaction. Subsequently, stirring was continued at 40 ° C. for 24 hours to perform a hydrolysis treatment.

  Thereafter, a large excess of water was added to the dope to precipitate cellulose acetate propionate. The precipitated powder was filtered, washed with water and filtered three times repeatedly, further treated with 0.02% dilute sulfuric acid at 50 ° C. for 1 hour, washed with water and filtered three times.

  The cellulose acetate propionate thus obtained had an acetyl group substitution degree of 2.0 and a propionyl group substitution degree of 0.7. This cellulose acetate propionate is designated as CAP2.

Example 1
The cellulose ester propionate (CAP1) 90 wt% obtained in Synthesis Example 1 and the plasticizer polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., PEG 600) 10 wt% were mixed using a 30 mmφ extruder to obtain a cellulose ester composition. A product pellet was obtained.

  The cellulose ester composition obtained as an island component was used as a sea component, using hot water-soluble polyethylene terephthalate copolymerized with 10.0 mol% of 5-sodium sulfoisophthalic acid and 35 mol% of isophthalic acid. A godet roller that is spun using a sea-island type composite die under conditions of a sea / island ratio of 50/50% by weight, cooled by a chimney wind at 25 ° C., then applied with an oil agent, converged, and rotated at 1000 m / min. Took over by.

  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. Subsequently, this sheet was immersed in hot water at 95 ° C. and repeatedly pressed with a mangle to remove sea components, thereby obtaining a non-woven sheet made of ultrafine fibers 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 moisture absorption difference (ΔMR) was 2.1%, indicating good moisture absorption and desorption. Since the single yarn fineness of the cellulose ester was sufficiently thin as 0.3 dtex, the softness of the texture and the napping of the napping were excellent. In addition, the color developability was also excellent.

Example 2 and Comparative Examples 3 and 4
An artificial leather was prepared in the same manner as in Example 1 except that the fineness of the single yarn was 0.5 dtex in Example 2, 0.7 dtex in Comparative Example 3, and 1.1 dtex in Comparative Example 4.

Table 1 shows the properties of the obtained artificial leather. In Comparative Example 3 in which the single yarn fineness was 0.7 dtex, the softness of the texture was seen in Comparative Example 4 in 1.1 dtex. there were.

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, since the napping density was low, judgment was bad and urethane of the ground was conspicuous.

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. In addition, the color was dull and the color development was inferior.

Examples 5 and 6
Cellulose ester composition was prepared by mixing 80 wt% of cellulose acetate propionate (CAP2) obtained in Synthesis Example 2 and 20 wt% of a plasticizer polyethylene glycol (manufactured by Sanyo Chemical Co., Ltd., PEG 600) using a 30 mmφ extruder. A product pellet was obtained.

  Artificial leather was obtained in the same manner as in Example 1 except that this composition was used as an island component and the fineness of cellulose ester single yarn was 0.3 dtex in Example 5 and 0.4 dtex in Example 6.

  The properties of the obtained artificial leather are shown in Table 3. The moisture absorption difference (ΔMR) was 2.5%, which was excellent in moisture absorption performance. Moreover, it was excellent also in each of texture softness, coloring property, and napping pruning.

Examples 7 and 8
Cellulose acetate butyrate (CAB-381-20 manufactured by Eastman Chemical Co., Ltd.) 90 wt% and plasticizer polyethylene glycol 10 wt% were mixed using a 30 mmφ extruder to obtain cellulose ester composition pellets.

  An artificial leather was obtained in the same manner as in Example 1 except that this composition was used as an island component, 0.3 dtex in Example 7, and 0.5 dtex in Example 8.

  The properties of the obtained artificial leather are shown in Table 3. Although the moisture absorption difference (ΔMR) was as low as 1.1%, it was excellent in terms of texture flexibility, color development and napping.

Claims (4)

Consists of at least one selected from cellulose acetate propionate and cellulose acetate butyrate, and mainly composed of a fiber entangled body mainly composed of cellulose ester fibers having a single yarn fineness of 0.5 dtex or less, and a polymer elastic body. Cellulose ester artificial leather. The cellulose ester-based artificial leather according to claim 1 , wherein the strength of the cellulose ester fiber is 1.2 cN / dtex or more. The cellulose ester-based artificial leather according to claim 1 or 2 , wherein the polymer elastic body is polyurethane. 2. 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 0.5 to 3%. The cellulose ester type artificial leather according to any one of to 3 .