JP3166054B2 - Method for producing artificial leather using water-based polyurethane resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing artificial leather using a water-based polyurethane resin, and more particularly to a method for dyeing an artificial leather raw material made of a water-based polyurethane resin with a liquid jet dyeing machine. The present invention relates to a method for producing artificial leather which has little resin detachment and is free from stains of a dyeing machine by a detached urethane resin.

[0002]

2. Description of the Related Art It is generally known that various polymer compounds are applied to a non-woven sheet-like material mainly composed of ultrafine fibers and processed to obtain artificial leather. An elastic polymer compound such as polyurethane is often used to obtain a soft and elastic feel as artificial leather and physical properties such as durability and dimensional stability. Moreover, these elastic polymer compounds are applied to a nonwoven sheet as a solution dissolved in an organic solvent, and are very often wet-solidified. However, the organic solvent used at this time is often a flammable and highly toxic substance, and much attention has to be paid to the recovery of the solvent in order to prevent the risk of fire and toxicity. Further, the solvent is expensive, and there is a drawback in that a great deal of cost is required for recovery from a dilute solution of water.
Due to these various drawbacks, various studies have been made to shift the elastic polymer compound to be applied to the nonwoven sheet from the organic solvent type to the aqueous polyurethane emulsion type. However, in the case of water-based polyurethane, it is necessary to apply sufficient heat for film formation, and the texture tends to be hard with a core like paper. In addition, there is a problem that migration is severe in the drying step of emulsion particles, and it is difficult to form an elegant surface which is a characteristic of artificial leather.

Conventionally, various attempts have been made to suppress the migration phenomenon in order to solve the above problem. For example, a synthetic emulsion containing a gelling agent and a heat-sensitive accelerator as disclosed in JP-A-52-28904 is adjusted to a heat-sensitive temperature of 45 ° C. or less, impregnated into a fiber base fabric, and heated to 90 ° C. or more. There is a method of gelling in a hot water bath. Although this method is certainly effective in suppressing migration and can be carried out on a laboratory scale, the drop of the emulsion into the hot water bath cannot be ignored in the actual production scale, and particularly, in the case of a low-concentration emulsion. Dropping occurs so severely that the degree of contamination in the hot water bath changes with time, the gelling property changes slightly, and it is not possible to produce a product of stable quality. Further, since the heat-sensitive temperature is low, the emulsion tends to be unstable under the influence of the room temperature and the water temperature which change throughout the year, and a product of a constant quality cannot be obtained.

A nonionic surfactant as a heat-sensitive accelerator has an effect of weakening the adhesive force between a resin and a fiber, and its effect is remarkably exhibited when the emulsion concentration is as low as 10% or less. In this case, the entanglement of the fibers in the non-woven sheet cannot be tolerated alone, a slip phenomenon between the fibers occurs, the nap on the product surface falls off, the wear resistance is extremely reduced, and the reinforcing cloth made of a knitted fabric is used. In the case of non-woven sheets without dyes, cutting during dyeing often occurs. Although it is thought that this is due to the weak adhesion, the resin itself comes off during the dyeing, causing a serious problem such as adhering to the wall of the dyeing machine or re-adhering to the product surface.

[0005] The present inventors have previously made a nonionic urethane emulsion emulsified by force to have an average particle size of 0.1 to 2.0.
Japanese Patent Application No. 5-124650 discloses a method for producing artificial leather, characterized in that a neutral salt containing a monovalent or divalent metal is dissolved and mixed as a heat-sensitive agent, and then heated and dried.
issue). By this method, the artificial leather made of water-based polyurethane was softened in feel, enhanced in mechanical properties such as abrasion resistance, and achieved a luxurious surface quality, and could be put to practical use. However, also in this method, there is a problem that the urethane resin falls off because it cannot withstand the hot water rubbing action in the liquid jet dyeing which is the mainstream of dyeing of textiles including artificial leather. When the dyeing temperature reaches 130 ° C., the shedding phenomenon is particularly remarkable. The dropped urethane resin agglomerates due to intervening bubbles and feather dust in the dyeing bath, and clogs the strainer portion or adheres to the wall of the gas phase machine, thereby severely contaminating the dyeing machine. When the contamination further proceeds, there is a disadvantage that a part is peeled off from the machine wall or the cloth is rubbed and re-attached to the cloth to cause a stain.

[0006] Further, the physical properties of the artificial leather product are greatly reduced, and particularly, the wear resistance is reduced more than expected, resulting in a feeling of lack of fulfillment. Therefore, in some cases, it is necessary to make extra attachment in anticipation of the detached portion, leading to an increase in cost. In order to avoid such troubles at the time of dyeing, there is a method of dyeing (pre-dying) before impregnating with an aqueous polyurethane, and then impregnating and applying an aqueous polyurethane resin. However, the artificial leather formed by this method lacks a feeling of fulfillment generally, has a strong core, and lacks suitability in the garment field where high fashionability is required.
Reducing the amount of urethane resin impregnated to solve the texture that leaves a core will not only result in a feeling of elasticity unique to artificial leather, fabric texture without a sense of fulfillment, but also consumption performance such as abrasion resistance and dimensional stability. Is significantly impaired. or,
Since the urethane resin is heated and dried at a high temperature of 100 ° C. or more after dyeing, there is a possibility that the color fastness may be lowered particularly in a dark color, and the dye preparation is naturally restricted. As described above, in the artificial leather provided with the water-based polyurethane resin, a true industrial production technique has not yet been established.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for dyeing an artificial leather raw material to which an aqueous polyurethane resin is applied with a liquid jet dyeing machine. An object of the present invention is to provide a method for producing artificial leather that does not cause contamination due to wall adhesion.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nonwoven sheet comprising, as at least a surface fiber layer, a fiber layer mainly composed of ultrafine fibers having a single fiber fineness of 0.5 denier or less. In order to produce an artificial leather by applying an aqueous polyurethane emulsion to the product and heating and drying the same, an inorganic salt is dissolved and mixed in advance as the aqueous polyurethane emulsion. Use a resin film prepared by drying with a dissolution rate of 12% or less in NN dimethylformamide (DMF) and adhesive strength of 1.2 g / cm or less after drying at 130 ° C. It is achieved by doing.

In general, in the formation of a water-based polyurethane film, a resin film is formed by bonding emulsion particles by heating and drying. In addition to the drying temperature,
It largely depends on the polymer composition and the concentration of the surfactant added for emulsification. If the film formation is weak, the adhesion performance as a binder and the strength physical properties as a film are of course insufficient, and the film cannot be tolerated by dyeing with hot water at 100 ° C. or more, especially at 130 ° C., and falls off. .
The present inventors have conducted intensive studies on the strength of film formation and the detachability by dyeing and rubbing, and have found that the strength of film formation has a deep relationship with the DMF dissolution rate. Generally, an aqueous polyurethane resin film is considered to be insoluble in DMF because it is crosslinked by heat. However, D having strong swelling action
When the film is immersed in the MF solution, the film swells and the weakly bonded portion dissolves, so that the strength of the film formation can be expressed by the dissolution rate. As an example, FIG. 1 shows the basic skeleton of 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI) and polytetramethylene glycol (PTMG).
Regarding two types of nonionic water-based polyurethane emulsions having an average particle size of 0.5 μm and different surfactant contents for emulsification, the heat treatment temperature of resin film and DMF
The relationship of the dissolution rate was shown. The surfactant content is 10% for the A type and 4 for the B type based on the solid content of the polyurethane resin.
%. It can be seen that by decreasing the content of the surfactant and increasing the heat treatment temperature, the DMF dissolution rate is reduced and the film formation is strengthened.

According to the study by the present inventors, when the DMF dissolution rate of the resin film is 12% or less, preferably 8% or less when the heat treatment temperature of the resin film is set at 120 ° C., the liquid flow at 130 ° C. The dropout rate in dyeing can be kept to 10% or less in terms of polyurethane resin. The reason why the temperature is set to 120 ° C. is that the performance of the resin is strictly evaluated by adopting a heat treatment condition lower than the dyeing temperature when the dyeing temperature is 130 ° C. at the maximum and the resin film performance is evaluated. Therefore, if the DMF dissolution rate is 12% or less at a heat treatment temperature of 120 ° C. or less, the film forming performance as a resin can be considered to be better, which is effective for high-speed production when increasing production.

A value of 10% or less of the urethane resin falling off at 130 ° C. in liquid flow dyeing corresponds to the falling off rate of the solvent-based polyurethane, and the film-forming property of the water-based polyurethane is comparable to the performance of the solvent-based polyurethane. You can think of it as being on a level. The ratio of solvent-based polyurethane in hot water rubbing dyeing is not zero, and this level is water-based considering that the molecular weight of a polyurethane polymer polymerized by water dispersion via a surfactant is not as high as that of a solvent-based polyurethane. It can be said that polyurethane is a phenomenal level. The dropout rate hardly changes even when a film is formed by a thermal gelation method containing a neutral salt. This is because the polyurethane resin and the salt undergo phase separation in the course of gelation by heating and drying, and the salt does not hinder film formation.

Another important point for achieving the object of the present invention is that the polyurethane resin has no tackiness. The use of an aqueous polyurethane resin limited in the DMF dissolution rate can prevent most of the dropouts caused by dyeing. However, since the polyurethane polymer has a molecular weight distribution, some of the low molecular weight regions are severe. It is almost impossible to completely eliminate the detachment under the liquid massage cloth because the bond is easily detached. It is important that the resin that has fallen off is not sticky and does not adhere to the dyeing machine. Particularly when polyester is considered as the material, it is desirable that the adhesiveness is low at a maximum of 130 ° C. In the actual dyeing process, dyeing is performed one after another. Therefore, even if it is slightly removed, if the adhesive is strong, it adheres to the gas phase wall and dead part in the dyeing machine, and contamination by accumulated deposits occurs. According to the study by the present inventors, the adhesive strength as tackiness is 130
When the dry heat treatment at 1.2 ° C. is 1.2 g / cm or less, adhesion inside the apparatus can be substantially suppressed. The value of 1.2 g / cm is a level at which almost no stickiness is felt even when the polyurethane resin film dried and heat-treated at 130 ° C. is touched with a finger. At 2.0 g / cm, a very sticky feeling is felt.

Next, a description will be given of the dyeing of the artificial leather raw material produced by the method of the present invention with a liquid jet rubbing. The rubbing effect of the liquid flow is determined by the nozzle structure, the liquid flow gap (clearance), and the nozzle pressure. There are various types of nozzle structures in accordance with the characteristics of the dough, but a structure that generates a vortex while spraying the dough at an angle of 45 ° to 60 ° is generally used. Regarding the relationship between the clearance (l) and the nozzle pressure (P), since the flow rate of the circulation pump is constant, (l) · (P) = constant regardless of the nozzle structure.
Therefore, the maximum nozzle pressure decreases as the clearance increases. If the nozzle structure is fixed, the effect of the pressure of the nozzle is larger than the effect of the clearance when the pressing effect is applied. The lower the pressure, the weaker the rubbing effect, the poorer the runnability of the dough, causing spotting and wrinkling. Although it is a direction of reduction for the dropping of polyurethane, it is not a desirable direction in order to provide a rich feeling of drape and a good feeling of fluffing. Further, if the pressure is too high, the fabric is seriously damaged and the commercial value is lost, and the running of the fabric becomes unstable and the management becomes impossible. An appropriate pressure range is 0.
5 to 2.5 kg / cm ² .

Next, the constituent conditions of the present invention will be described.
If the nonwoven sheet used in the present invention has a fiber layer mainly composed of ultrafine fibers having a single fiber density of 0.5 denier or less as the surface fiber layer, the layer connected to the surface fiber layer may be Any configuration sheet may be used. For example, a nonwoven sheet may be constituted by a fiber layer having the same constitution as the surface fiber layer. Further, as a layer connected to the surface fiber layer, the entire surface is covered with the surface fiber layer, and three-dimensional entanglement is performed. A layer made of a knitted fabric may be arranged. In the latter case, an arbitrary sheet-like material may be connected to the lower layer of the knitted fabric. The nonwoven sheet having a knitted fabric layer has sufficient strength and dimensional stability even with a rubbing cloth at the time of dyeing, and the amount of the polyurethane resin is small, and the cost is low. . The fiber material of the ultrafine fibers having a single fiber fineness of 0.5 denier or less is not particularly limited as long as it is used for ordinary artificial leather. For example, polyethylene terephthalate (PET), nylon 6, nylon 66 , Polyacrylonitrile and the like can be used.

As the ultrafine fibers, those directly spun by ordinary wet, dry and contact spinning methods, melt blown method, a method of extracting and removing one component from sea-island type fibers and polymer-blended fibers, and splitting Those obtained by a thread method or the like can be used. In the present invention, a nonwoven sheet having a surface fiber layer mainly composed of ultrafine fibers having a single fiber fineness of 0.5 denier or less obtained by the above method is used. When the single fiber fineness is 0.5 denier or more, the rigidity of the fibers is large and the surface nap is strong, so that it is possible to obtain the high-grade surface quality, feel, and writing effect unique to artificial leather. Absent. Further, it is possible to mix a small amount of hot water-soluble short fibers (for example, vinylon) into the nonwoven sheet-like material as long as the object of the present invention is not hindered. The non-woven sheet is prepared from the above-mentioned various types of ultrafine fibers by a dry method such as card, cross layer, random webber or the like, or by a wet papermaking method in which the ultrafine fibers are dispersed in water. And entangled and integrated by a needle punch, a fluid entanglement treatment or the like.

The aqueous polyurethane emulsion of the present invention is a nonionic emulsion which is forcibly emulsified in water with a high mechanical shearing force in the presence of an emulsifier, for example, a nonionic emulsifier, a weak anionic emulsifier, etc. Has an average particle diameter of 0.1 to 2.0 μm, which is slightly larger than ordinary urethane emulsion particles. Examples of the forced emulsification method for obtaining the aqueous polyurethane emulsion of the present invention include a phase inversion emulsification method in which a liquid polyurethane polymer after completion of the reaction is emulsified with the emulsifier, and an emulsification and / or emulsification of terminal isocyanate prepolymer. And the like. A prepolymer method obtained by completing the chain extension reaction with a chain extender such as a type and obtaining a high molecular weight is used, and a prepolymer method is particularly preferable for obtaining a particularly good abrasion sheet.

In order to improve the emulsifying and dispersing properties, an ethylene oxide or propylene oxide adduct or a weak carboxylic acid group may be introduced into the polymer molecular skeleton of the polyurethane to improve the heat resistance and the water resistance. For the purpose of improvement, trifunctional glyco- such as trimethylolpropane
Modification means by modifying the polyurethane itself, such as by forming a crosslinked structure by reacting a polyamine, a trifunctional amine, or the like, is also suitably used in the present invention. In the aqueous polyurethane emulsion of the present invention, the average particle diameter of the emulsion particles is 0.1%.
If it is less than μm, it is difficult to carry out the method of the present invention industrially and stably. If it exceeds 2.0 μm, the stability of the emulsion will be poor, but the film-forming properties of the resin will also be poor, and it will not be possible to satisfy the shedding and abrasion resistance during dyeing.
The inorganic salts mixed and added to the emulsion include neutral salts of alkali metals or alkaline earth metals, such as monovalent or divalent sulfates, nitrates and chlorides. For example, NaC
1, Na ₂ SO ₄ , NaNO ₃ , CaSO ₄ ,
CaCl ₂ , MgCl _{2 and the} like can be mentioned. Na ₂ SO ₄ is most effective when comprehensively considered in terms of process control, availability of raw materials, economic efficiency, pollution, and the like.

The concentration of the inorganic salt to be added cannot be determined unconditionally because the gelling property differs depending on the kind of the salt, but it is preferably 1 to 10% with respect to the emulsion. Addition of large amounts of inorganic salts may cause the emulsion to gel at room temperature. Examples of the composition of the polyurethane component constituting the aqueous polyurethane emulsion of the present invention include the following. Polyol components include polyesterdiols such as polyethylene adipate glycol and polyethylene adipate glycol; and polyether glycols such as polyethylene glycol and polytetramethylene glycol.
And polycarbonates and the like. As the isocyanate component, diphenylmethane-4,
Aromatic diisocyanates such as 4'-diisocyanate;
Alicyclic diisocyanates such as dicyclohexylmethane-4,4'-diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate;

Examples of the chain extender include glycols such as ethylene glycol; ethylenediamine, 4,4'-
Examples thereof include diamines such as diaminodiphenylmethane. The raw material polyurethane can be obtained by appropriately combining the above various components. In the emulsion, if necessary, stabilizers such as ultraviolet absorbers and antioxidants, coloring agents such as pigments, alcohols and surfactants such as penetrants, antimicrobial agents, thickeners, polyvinyl alcohols, etc. , CMC
And a heat-sensitive accelerator such as polyvinyl methyl ether. Non-woven fabric of water-based polyurethane emulsion containing inorganic salts
The method of imparting the material to the substrate can be carried out by any method such as a conventional impregnation method, spraying method, coating method and the like. The amount (solid content) of the polyurethane resin constituting the aqueous polyurethane emulsion may be any value depending on the purpose. Generally, the amount is 3 to 100 parts by weight based on 100 parts by weight of the nonwoven sheet.

Further, as a specific method of heating and drying, any heating means such as hot air drying, infrared heating, and high frequency heating can be applied. However, from the viewpoint of the amount of capital investment and ease of maintenance, a pin tenter or clip is used. A hot air dryer such as a tenter is generally used. The drying temperature is equal to or higher than the gelation temperature of the water-based polyurethane emulsion imparted with heat sensitivity. Generally, the gelation temperature of the above emulsion is preferably set to 60 to 80 ° C., since the emulsion does not gel before heating. In order to sufficiently exhibit the performance of the gelled resin, at least 110 ° C is required, and desirably 130 ° C or more. However, considering the heat resistance of the resin and the deterioration of the fiber, 180 ° C
The above should be avoided.

[0021]

The present invention is illustrated by the following examples, which do not limit the scope of the invention. The physical properties as artificial leather were measured after circular dyeing. The measuring method of each measured value used in the description of the examples is as follows. Average particle diameter: Measured by a light transmission centrifugal sedimentation method using an automatic particle diameter measuring apparatus manufactured by Horiba Seisakusho using water as a dispersion medium at a disk rotation speed of 3000 rpm, and expressed as a volume-based median diameter.

DMF dissolution rate: A stock solution of an aqueous polyurethane resin emulsion is coated on a glass plate with an applicator of 0.25 mm and dried in a greenhouse at 25 ° C. for 20 hours to form a film. Next, the film is put together with the glass plate in a hot air dryer at 120 ° C. and heat-treated for 20 minutes. Peel the polyurethane film from the glass plate,
Weight cut into 0 cm square size (W ₁ )
Is measured. Next, after being immersed in a DMF stock solution (25 ° C.) for 6 hours, it was dried in a dryer at 60 ° C. and weighed (W ₂ ).
Is measured. The dissolution rate is determined from the weight loss excluding the surfactant in the polyurethane resin. Adhesion; heat-treated film is made as described above. This polyurethane film was treated in hot water at 130 ° C. for 30 minutes assuming a dyeing process, and then treated at 80 ° C. for 15 minutes in a solution containing 2 g / l of caseide and thiourea dioxide. Dry in a dryer at ℃. A nonwoven fabric sheet made of polyester made of ultrafine fibers of 0.5 d / f or less is piled on this film, sandwiched between glass plates in a sandwich shape, and treated at 130 ° C. for 30 minutes in a hot air dryer. At this time, the load of the glass plate applied to the film was kept constant at 15 g / cm ² . Take out the integrated material of the film and non-woven sheet, cut into 2.5cm width, and measure the strength of the bonded surface with a tensile strength and elongation measuring machine

Softness: L-1079-A method (45 ° C.
Cantilever method) Abrasion strength; L-1096 method (Martindale method) Breaking strength; L-1096-A method (strip method) Tear strength; L-1096-D method (Pendulum method) (Example 1) PET ultrafine fibers having a single fiber fineness of 0.1 denier were produced by a direct spinning method, and the short fibers cut to a length of 5 mm were dispersed in water to obtain a papermaking slurry. The slurries were made into a nonwoven sheet having a basis weight of 50 g / m ² . 75 denier / 36 filament PET
The nonwoven sheet was laminated on both sides of a plain woven fabric having a basis weight of 50 g / m ² , and three-dimensionally entangled and integrated by high-speed water jet. The high-speed water flow was injected at a pressure of 30 kg / cm ² from a straight flow injection nozzle having a hole diameter of 0.1 mm.

The laminated sheet has a suction device on the lower surface.
A high-pressure water stream was impinged on the mesh wire net at a position 30 mm from the nozzle. This operation is performed from both sides of the laminated sheet, and the basis weight is 150 g / m ² and the thickness is 0.55 mm.
Was prepared. The surface of the sheet was buffed at a paper speed of 700 m / min using # 400 emery paper. In addition to this, "S-
Perflex "(forced emulsification type nonionic solid content 45
%) A polyether-based water-based polyurethane emulsion having an average particle size of 0.5 μm, a DMF dissolution rate of 7%, and a tackiness of 1.0 g / cm in adhesive strength at a concentration of 6%, and Na ₂ SO ₄ 3% as a heat-sensitive agent Impregnated with the prepared liquid,
Aperture 1 so that pickup rate is 150% with mangle
It was dried by heating for 3 minutes with a 30 ° C. pin tenter dryer. A nozzle pressure of 1.0 g / cm was applied to this artificial leather raw material using a circular dyeing machine set to a bath ratio of 1:30 in a 70 l bath.
After dyeing at 10 ° C. for 30 minutes at a concentration of 10% of a blue-based disperse dye, thiourea dioxide and caseida at a concentration of 2 g / l each were used for 8 minutes.
After reducing and washing at 0 ° C. for 15 minutes, it was dried and finished. At this time, the urethane resin shedding rate was as small as 5% as calculated from the weight change before and after dyeing. After dyeing, the 20 ^# strainer was taken out, and the attached matter was observed. However, there was almost no attached matter, and cleaning could be performed by simple washing with water. The physical properties of the obtained artificial leather were as follows, and had a feeling of fulfillment and a luxurious feeling with a raised brush.

[0025]

[Table 1]

(Comparative Example 1) A nonwoven sheet similar to that in Example 1 was treated with "Superflex" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
Except that the F dissolution rate was 14% and the tackiness was 3.5 g / cm in adhesive strength, the same polyether-based water-based polyurethane emulsion as in Example 1 was used, processed and dyed under the same conditions as in Example 1, and finished. . The polyurethane resin shedding rate of this was surprisingly high at 40%. Adhesive deposits were observed on the 20 ^# strainer after dyeing, and the deposits could not be removed without firm rubbing with a wire brush. The physical properties of the obtained artificial leather are as follows, and it has a rough and brushed long brushed texture with a fluffy feel and a tight texture.

[0027]

[Table 2]

(Example 2) The same artificial leather raw material as in Example 1 was dyed with a circular dyeing machine at a nozzle pressure of 2.0 g / cm and finished. At this time, the dropout rate of polyurethane resin is 6%
After all it was few. 20 ^# Simple washing with water without adhesion to the strainer. The physical properties of the obtained artificial leather are as follows. The texture is soft and has excellent drapability while leaving a feeling of fulfillment, and exhibits an elegant lighting effect without raising or damaging at all.

[0029]

[Table 3]

(Comparative Example 2) The nonwoven sheet used in Example 1
"Super Flex" series manufactured by Daiichi Kogyo Pharmaceutical Company
Water-based polyester-based polyurethane emulsion having an average particle size of 1.0 μm (forced emulsification type nonionic fixed component 5
(0%), the DMF dissolution rate was as good as 6%, but the adhesive having a high adhesive strength of 5 g / cm was processed and dyed under the same conditions as in Example 1. Although the polyurethane resin falling rate of this product was as small as 7%,
The 20 ^# strainer could not be removed by simple washing with water, but was cleaned with a wire brush. It was foreseen that large amounts of staining would clearly cause problems.

Example 3 PET ultrafine fibers having a single fiber fineness of 0.1 denier were produced by a direct spinning method, and the length was 5 m.
cut into m, sheet-forming Sri dispersed in water - and then, the sheet basis weight 75 g / m ² - which was used as a surface layer component manufacture and. As a back layer component, a nylon 66 single fiber fineness of 1.0 denier cut to 10 mm was similarly dispersed in water to produce a sheet having a basis weight of 100 g / m ² . The two-component nonwoven sheets were laminated, treated with a high-speed water flow having a pore diameter of 0.1 m at a water pressure of 40 kg / m ² , and three-dimensionally entangled and integrated. This sheet-like material was # 400 emery paper.
The superfine yarn layer on the surface was buffed at a paper speed of 900 m / min. This non-woven sheet has an average particle size of 0.8 μm.
m polyether-based water-based polyurethane emulsion ("Superflex" solid content 45, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
%), The DMF dissolution rate is 6%, and the tackiness is 1.2 g in adhesive strength.
/ Cm was prepared by adding 5% of NaCl as a heat sensitive agent at a concentration of 11%, and was squeezed by a mangle so as to have a pickup rate of 120%. Then, it was dried by heating at 130 ° C. for 3 minutes with a pin tenter dryer. This was dyed and finished under the same dyeing conditions as in Example 1. Finishing was performed without cutting in the dyeing machine, and there was no problem with the urethane resin falling off rate of 5%. Cleaning of the strainer after dyeing was easy because there was no deposit and no tackiness. The physical properties of the obtained artificial leather are as follows, and it has a texture with a volume feeling, has sufficient mechanical strength, and is suitable as a backing material for shoes.

[0032]

[Table 4]

(Comparative Example 3) Nonwoven fabric used in Example 3
The DMF dissolution rate is 22% and the adhesiveness is 1.2
The same processing was performed using the same polyether-based water-based urethane emulsion as in Example 3 except for g / cm and other conditions. However, it could not be cut during dyeing and finished as a product.

[0034]

As described above, by applying a specific aqueous polyurethane emulsion to a nonwoven sheet-like material mainly composed of ultrafine fibers, the polyurethane resin can be largely prevented from falling off during liquid jet dyeing, and the polyurethane resin has fallen off. Since there is no contamination by the resin, it is possible to industrially and stably provide an artificial leather having a graceful surface quality, being soft and having good abrasion resistance.

[Brief description of the drawings]

FIG. 1 shows a relationship between a resin film, a heat treatment temperature, and a DMF dissolution rate for two types having different surfactant content.

Claims (1)

(57) [Claims] An aqueous polyurethane emulsion is applied to a non-woven sheet comprising at least a fiber layer mainly composed of ultrafine fibers having a single fiber fineness of 0.5 denier or less as a surface fiber layer, followed by drying by heating. When manufacturing artificial leather,
In a method using a treatment liquid in which inorganic salts are previously dissolved and mixed in the aqueous polyurethane emulsion, the dissolution rate of the resin film prepared by drying the aqueous polyurethane emulsion in NN dimethylformamide is 12% or less, The adhesive strength after dry heat treatment at 130 ° C is 1.
A method for producing artificial leather using an aqueous polyurethane resin, characterized by using an aqueous polyurethane emulsion of 2 g / cm or less.