JP5731654B2 - Artificial leather and method for producing the same - Google Patents

Description

  The present invention relates to an artificial leather and a method for manufacturing the same, and more specifically to an artificial leather that can replace natural leather and a method for manufacturing the same.

  Artificial leather is made by impregnating a non-woven fabric in which ultrafine fibers are entangled in three dimensions with a polymer elastic body, and has a soft texture and a unique appearance very similar to natural leather. It is widely used in various fields such as clothing, gloves, miscellaneous goods, furniture, and automobile interior materials.

  Such artificial leather is manufactured using various types of fibers such as polyethylene terephthalate fibers and polyamide fibers.

  However, ordinary artificial leather consists of one component short fiber. Therefore, the short fibers constituting the artificial leather have mechanical properties similar to each other and exhibit similar entanglement behavior. As a result, the distances and gaps between the short fibers are substantially the same. Moreover, since the interaction between the short fibers does not change so much, there is a problem that it is difficult to realize an artificial leather having a satisfactory touch feeling, volume feeling and flexibility.

  On the other hand, in order to give the artificial leather a volume feeling like natural leather, a method of increasing the density of the nonwoven fabric in the shrinking process has been proposed. In addition, a softener treatment method, a tumbling treatment method, and the like for improving the flexibility of artificial leather have been proposed.

  However, these methods may impair characteristics such as the touch and appearance of the artificial leather.

  Therefore, the present invention provides an artificial leather that can solve the problems due to limitations and disadvantages of the related art and a method for manufacturing the same.

  The present invention starts from the awareness of the problem that a drastic method for improving the physical properties of artificial leather, such as controlling the internal structure of a nonwoven fabric, should be devised.

  The present invention includes not only excellent tactile sensation, flexibility, breathability and volume feeling, but also an artificial weight that can dramatically reduce the weight by including two or more kinds of short fibers each made of different components. Provide leather.

  In addition, the present invention includes not only excellent tactile sensation, flexibility, breathability and volume feeling, but also an epoch-making weight reduction by including two or more kinds of short fibers respectively produced with different components. A method for producing artificial leather is provided.

The present invention includes a non-woven fabric containing short fibers having a fineness of 0.001 to 0.5 denier, and a polymer elastic body impregnated in the non-woven fabric, wherein the short fibers are a repeating unit of —CH ₂ —. There is provided an artificial leather characterized by being two or more polyester-based short fibers having different numbers of repeating units.

In the present invention, the step of preparing two or more types of sea-island type composite fibers containing a sea component and an island component--wherein the island components of the two or more types of sea-island type composite fibers have a repeating unit of —CH ₂ —. And a step of forming a nonwoven fabric with the two or more types of sea-island type composite fibers, and eluting sea components of the two or more types of sea-island type composite fibers. Provided is a method for producing artificial leather including a step of forming a nonwoven fabric.

  The above general description and the following detailed description are all for the purpose of illustrating and explaining the present invention and are intended to provide a more detailed description of the claimed invention.

  The artificial leather of the present invention contains two or more kinds of polyester short fibers having different elastic recovery forces. Among them, the short fibers having high elastic recovery force form a spring-like structure during the entanglement process for forming the nonwoven fabric.

Since the artificial leather of the present invention partially includes such a spring structure, it has superior compressive elasticity compared to artificial leather containing only polyethylene terephthalate ( _two repeating units —CH ₂ —) short fibers ( (Thickness direction), and there are uniformly formed voids of uniform size inside. Therefore, it is possible to provide an artificial leather that not only has excellent tactile sensation, flexibility, breathability, and volume feeling, but also can achieve an epoch-making weight reduction.

  Furthermore, since such a spring structure has the characteristic of standing up the surface fluff, variation in the coefficient of friction due to the direction of the fluff is minimized as compared to normal artificial leather in which the fluff lies in one direction. Artificial leather can be manufactured. Therefore, the artificial leather of the present invention can remarkably reduce discomfort caused by a difference in friction characteristics depending on directionality.

On the other hand, when the nonwoven fabric is composed of only one type of polyester-based short fiber having three or more —CH ₂ — repeating units, a spring structure is easily formed internally, but it is difficult to entangle the short fibers. Therefore, the density and mechanical strength of the nonwoven fabric are reduced, and as a result, it is not possible to produce artificial leather having the required appearance, touch and physical properties.

  Moreover, since the nonwoven fabric of this invention contains a polyester-type short fiber, it has the adhesiveness outstanding with the polymeric elastic body, for example, polyurethane. Therefore, the artificial leather of the present invention has excellent durability.

  The artificial leather of the present invention having such excellent physical properties can be widely used in various fields such as footwear, clothing, gloves, miscellaneous goods, furniture, and automobile interior materials.

  Obviously, various modifications and variations of the present invention are possible without departing from the spirit and scope of the invention. Accordingly, this invention includes all modifications and variations that fall within the scope of the claimed invention and its equivalents.

  Examples of the artificial leather and the method for producing the same according to the present invention will be specifically described below.

  The artificial leather of the present invention includes a nonwoven fabric and a polymer elastic body impregnated in the nonwoven fabric.

  The nonwoven fabric includes short fibers having a fineness of 0.001 to 0.5 denier. A nonwoven fabric made of short fibers having a fineness in this range comes to have an excellent tactile sensation. When the fineness of the short fibers is less than 0.001 denier, the touch of the nonwoven fabric is improved, but the production is not easy, and the washing fastness indicating the degree of dye loss may be lowered after washing. And when the fineness of the said short fiber exceeds 0.5 denier, the tactile feeling of a nonwoven fabric may fall.

  The fineness of the short fiber is measured by preparing a sample using a gold coating method, photographing a cross section of the sample at a constant magnification using a scanning electron microscope (SEM), and measuring the diameter of the short fiber. Thus, the diameter of the short fiber measured can be calculated by the following formula.

Fineness (denier) = 9πD ² ρ / 4000

In the above formula, π is the circular ratio, D is the diameter (μm) of the cross section of the short fiber, and ρ is the fiber density (g / cm ³ ).

The nonwoven fabric of the present invention contains two or more polyester short fibers. The two or more types of polyester short fibers have a repeating unit of —CH ₂ —. However, different types of short polyester fibers each have a different number of repeating units of —CH ₂ —.

  Further, the two or more kinds of polyester short fibers may each have 2 to 4 repeating units. For example, the nonwoven fabric may include two or more kinds of short fibers among polyethylene terephthalate (PET) short fibers, polytrimethylene terephthalate (PTT) short fibers, and polybutylene terephthalate (PBT) short fibers.

  Polyethylene terephthalate short fibers are relatively inexpensive and have excellent tensile strength. Moreover, since it has a high melting point, the polyethylene terephthalate short fibers have excellent heat resistance. Therefore, the nonwoven fabric of this invention can contain a polyethylene terephthalate short fiber fundamentally as one of the said 2 or more types of polyester-type short fiber.

  In the nonwoven fabric, the content of the short polyethylene terephthalate fiber is 5 to 95% by weight, preferably 10 to 50% by weight. If the content of the short polyethylene terephthalate fiber is less than 5% by weight, the mechanical strength of the nonwoven fabric may be lowered. If the content of the short polyethylene terephthalate fiber exceeds 95% by weight, the nonwoven fabric is constituted. Short fibers cannot form a dense structure, and as a result, the tactile sensation, flexibility, and volume of the artificial leather manufactured by the nonwoven fabric may be lowered.

  One factor affecting the feel, flexibility, and volume of the artificial leather is how uniformly the short fibers of the nonwoven fabric used for the production of the artificial leather are mixed. In the present invention, the two or more types of polyester short fibers are uniformly mixed so that the nonwoven fabric has a weight variation coefficient (CV%) of 20% or less. If the weight variation coefficient of the nonwoven fabric exceeds 20%, the tactile sensation, flexibility and volume feeling of the artificial leather produced from the nonwoven fabric will be reduced.

  The weight coefficient of variation (CV%) is obtained by randomly collecting a sample from a nonwoven fabric, measuring the weight per unit area of the sample, calculating the standard deviation and arithmetic average using the weight per unit area, Obtain the coefficient of variation from the equation.

  Coefficient of variation (CV%) = standard deviation / arithmetic mean

  Different types of short polyester fibers constituting the nonwoven fabric of the present invention can have different “elastic recovery rates at 20% elongation”.

  In one embodiment of the present invention, there is a maximum value and a minimum value among the “elastic recovery rates at 20% elongation” of different types of short fibers constituting the nonwoven fabric of the present invention, and the minimum value with respect to the maximum value. The ratio is 10 to 80%.

  If the ratio of the minimum value to the maximum value of the elastic recovery rate at 20% elongation is within the above range, not only the two or more kinds of short fibers constituting the nonwoven fabric can be intertwined closely but also a relatively high elastic recovery. Short fibers having a rate can form a spring-like structure. Therefore, the artificial leather manufactured with such a nonwoven fabric can exhibit excellent tactile sensation, flexibility and volume feeling.

If the ratio of the minimum value to the maximum value of the elastic recovery rate at 20% elongation is less than 10%, two or more kinds of short fibers can be intertwined closely, but the spring structure is formed inside the nonwoven fabric. It is difficult to form. Therefore, the tactile sensation, flexibility and volume feeling of the artificial leather may be reduced.
Moreover, when the ratio of the minimum value to the maximum value of the elastic recovery rate at 20% elongation exceeds 80%, the nonwoven fabric itself may not be easily manufactured.

  The compression elastic characteristics in the thickness direction of the artificial leather are improved by the short fibers having a relatively high elastic recovery rate forming the spring structure. The compression elastic characteristic can be expressed by a compression rate and a restoration rate. That is, the artificial leather of the present invention formed of the nonwoven fabric has a compression rate (thickness direction) of 8% to 50%. When the compression ratio of the artificial leather is less than 8%, a stiff feeling is expressed, and when the compression ratio exceeds 50%, the texture such as volume is lowered.

  On the other hand, the restoration rate indicates the degree of recovery when the load is removed after compression. The artificial leather of the present invention made of the nonwoven fabric has a restoration rate of 80% or more. If the restoration rate of the artificial leather is less than 80%, the form stability and volume feeling of the artificial leather are lowered, and a high-quality texture cannot be provided.

  A fiber having a high elastic recovery rate is excellent in recovery characteristics against external force. When the artificial leather contains fibers having a high elastic recovery rate, the uprightness of the surface fluff formed by a grinding process such as a buffing process is further increased due to the internal spring structure. Therefore, the difference in the friction coefficient between the forward direction (fluff direction) and the reverse direction of the surface of the artificial leather is remarkably reduced, the difference in the texture due to the direction of the surface of the artificial leather is reduced, and the different texture due to the direction is minimized. Surface tactile sensation can be improved. The smaller the difference between the forward and reverse friction coefficients, the better the tactile feel of artificial leather. In one embodiment of the present invention, the friction coefficient difference is 0.30 or less.

The two or more types of polyester short fibers constituting the nonwoven fabric of the present invention have a length of 5 to 100 mm. When the short fibers having a length in this range are intertwined, the manufacturing process of the nonwoven fabric can be improved, and the artificial leather manufactured with such a nonwoven fabric can exhibit excellent physical properties. If the length of the short fiber is less than 5 mm, it is difficult to produce a nonwoven fabric, and the strength and feel of the artificial leather may be lowered.
Moreover, when the length of the said short fiber exceeds 10 mm, manufacture of a nonwoven fabric may become difficult.

Polyurethane can be used as the polymer elastic body impregnated in the nonwoven fabric. For example, a polycarbonate diol type, a polyester diol type or a polyether diol type alone or a mixture thereof can be used.
Polysiloxane can also be used as the polymer elastic body. However, the polymer elastic body is not limited to polyurethane or polysiloxane.

  The content of the polymer elastic body in the artificial leather is preferably 20 to 30% by weight. When the content of the polymer elastic body is less than 20% by weight, the required elongation cannot be obtained, and when the content of the polymer elastic body exceeds 30% by weight, the tactile sensation of the artificial leather decreases, The risk of discoloration of artificial leather increases and the elongation of artificial leather also decreases.

  The artificial leather of the present invention preferably has an “elastic recovery rate at 10% elongation” of 80% or more. Artificial leather having an elastic recovery rate of 80% or more can easily return to its original shape when the pressure is removed even when subjected to pressure for a long time. When the artificial leather of the present invention is used for the production of footwear, clothing, gloves, miscellaneous goods, furniture, automobile interior materials, etc. due to such an excellent elastic recovery rate, the product is free of wrinkles and is natural and high-grade. Appearance of the product can be realized.

  Below, the manufacturing method of artificial leather is demonstrated in detail by one Example of this invention.

First, two or more types of sea-island type composite fibers including sea components and island components are prepared. Specifically, after preparing a sea component polymer melt and an island component polymer melt, a filament is produced by performing composite spinning through a composite spinning die.
The filament is then stretched. A crimp is formed on the drawn filament, and the filament provided with the crimp is cut to a predetermined length, thereby completing a sea-island type composite fiber having a short fiber shape.

In the present invention, the island component of the two or more sea-island type composite fibers is a polyester polymer having a repeating unit of —CH ₂ —, and the number of repeating units is different.

  That is, the first sea-island type composite fiber can include the first and second polymers as the sea component and the island component, and the second sea-island type composite fiber can include the first and second as the sea component and the island component. Three polymers can be included. Of course, a third sea-island composite fiber containing the first and fourth polymers as the sea component and the island component can be further prepared. That is, the first to third sea-island type composite fibers can each contain the same polymer as the sea component and different polymers as the island component. The first polymer is different from the second to fourth polymers in the property of being dissolved in a solvent at the time of sea component elution described later.

  For example, the second polymer may be polyethylene terephthalate (PET), the third polymer may be polybutylene terephthalate (PBT), and the fourth polymer may be polytrimethylene terephthalate (PTT).

  Next, a nonwoven fabric is formed with the two or more sea-island type composite fibers.

  Specifically, by performing an opening, blending, and carding process on the two or more kinds of sea-island composite fibers, the short-sea-shaped sea-island composite fibers are uniformly mixed to produce a web. Thereafter, the obtained web is laminated through a cross-wrapping step, and then the nonwoven web is manufactured by bonding the laminated webs while interlacing the sea-island composite fibers by needle punching.

  The step of producing a web by mixing two or more kinds of sea-island type composite fibers can also be performed using an air raid method using an air jet, a paper making method mixed in water, or the like.

  The step of entanglement of the two or more sea-island composite fibers may be performed by a high-speed fluid treatment method, a chemical bond method, or a hot air through method.

The thus produced nonwoven may have a basis weight of 100~700g / ^{m 2.} The final product completed using a nonwoven fabric having this unit weight will have an optimal density.

  Next, the nonwoven fabric is impregnated with a polymer elastic body.

  For example, a polymer elastic body solution is prepared, and the nonwoven fabric is immersed in the solution. The polymer elastic body solution can be prepared by dissolving or dispersing polyurethane in a predetermined solvent. For example, the polymer elastic body solution can be prepared by dissolving polyurethane in dimethylformamide (DMF) or dispersing polyurethane in water. Alternatively, the silicone elastic polymer may be used as it is without dissolving or dispersing the elastic polymer in a solvent or dispersion medium.

  In addition, pigments, light stabilizers, antioxidants, flame retardants, softeners, colorants and the like may be added to the polymer elastic body solution.

  Before the non-woven fabric is immersed in the polymer elastic body solution, the non-woven fabric can be padded with an aqueous polyvinyl alcohol solution to stabilize its form.

  By adjusting the concentration of the elastic polymer solution, the amount of the elastic polymer impregnated in the nonwoven fabric can be adjusted. Considering that the content of the polymer elastic body contained in the final artificial leather is 20 to 30%, the concentration of the polymer elastic body solution is preferably adjusted to a range of 5 to 20% by weight. The nonwoven fabric is preferably immersed in the polymer elastic body solution for 0.5 to 15 minutes in a state where the temperature of the 5 to 20% by weight polymer elastic body solution is maintained in the range of 10 to 30 ° C. .

  After the nonwoven fabric is immersed in the polymer elastic body solution, the polymer elastic body impregnated in the nonwoven fabric is solidified in a coagulation tank, and then washed with water in a water washing tank. When the polymer elastic body solution is obtained by dissolving polyurethane in dimethylformamide, the coagulation tank is composed of a mixture of water and a small amount of dimethylformamide, and the polymer elastic body is formed in the coagulation tank. While solidifying, dimethylformamide contained in the non-woven fabric can be eluted into the coagulation tank, and in the washing tank, the polyvinyl alcohol padded on the non-woven fabric and the remaining dimethylformamide are removed from the non-woven fabric.

  Next, the non-woven fabric impregnated with the polymer elastic body is subjected to heat calendering. The thermal calendering can be performed by passing a non-woven fabric impregnated with the polymer elastic body through a heated roller and applying pressure. The temperature of the heating roller can be maintained in the range of 80 to 200 ° C. If the temperature of the heating roller is less than 80 ° C., a sufficient heat calendering effect cannot be obtained, and the temperature of the heating roller is 200 If the temperature exceeds ℃, the short fibers on the nonwoven fabric surface may be damaged.

  The polymer elastic bodies are rearranged through such a heat calendering process, and the short fibers on the surface of the nonwoven fabric are evenly arranged, so that the surface of the nonwoven fabric can be uniformly raised in the finishing step described later.

  The sea component is then removed from the heat calendered nonwoven. When the sea component of two or more kinds of sea-island type composite fibers constituting the nonwoven fabric is eluted, only the island component remains and an ultrafine nonwoven fabric composed of ultrafine fibers is formed. The sea component elution step can be performed using an alkaline solvent such as an aqueous caustic soda solution.

  In the case of the non-woven fabric manufactured with the first to third sea-island type composite fibers, the first polymer that is the sea component is eluted, so that only the second to fourth polymers that are the island component remain and become ultrafine. An ultra-fine nonwoven fabric composed of the short fibers thus formed is formed.

  In addition, the above-described impregnation step of the polymer elastic body may be performed after the ultrathinning step, not before. That is, instead of impregnating the polymer elastic body into the nonwoven fabric before the ultrathinning step, the polymer elastic body can be impregnated into the ultrathin nonwoven fabric formed by the ultrathinning step.

  Next, raising is performed on the ultrafine nonwoven fabric. The napping step is a step of generating a large amount of fluff on the surface of the non-woven fabric by wearing the surface of the ultra-fine non-woven fabric with a polishing tool such as sandpaper.

  Next, the napped nonwoven fabric is dyed and finished to complete the production of artificial leather according to the present invention.

  The artificial leather produced in this way has a compression rate of 8-50% and a restoration rate of 80% or more, and the difference in friction coefficient between the forward direction (fluff direction) and the reverse direction of the surface is 0.30 or less. is there.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the following examples are for helping understanding of the present invention, and the scope of rights of the present invention should not be limited thereby.

Example 1

  Polyethylene terephthalate, which is an island component, and copolymer polyester, which is a sea component, are composite-spun to form a filament, and the filament is drawn, crimped, and cut to form a short fiber having a fineness of 3.5 denier and a length of 50 mm. A first conjugate fiber was produced. The content of polyethylene terephthalate which is an island component of the first composite fiber was 70% by weight, and the content of copolymerized polyester which was a sea component was 30% by weight.

  Further, except that polytrimethylene terephthalate was used as an island component, a short fiber shape having a fineness of 4.0 denier and a fiber length of 51 mm was obtained in the same manner as the first composite fiber production method. Of the second composite fiber. The content of polytrimethylene terephthalate as an island component of the second composite fiber was 70% by weight, and the content of copolymer polyester as a sea component was 30% by weight.

  Next, after the contents of the first conjugate fiber and the second conjugate fiber were charged so as to be 90% by weight and 10% by weight, respectively, opening and blending were performed, and the carding / cross wrapping process was performed. After forming a web laminated body, the nonwoven fabric was manufactured by bonding the web of this laminated body by needle punching.

  Next, the nonwoven fabric was heat-shrinked at a high temperature to increase the density of the nonwoven fabric. Thereafter, the high-density nonwoven fabric was immersed in a 15% by weight polyurethane solution obtained by dissolving polyurethane in dimethylformamide (DMF) for 8 minutes, and then the polyurethane was coagulated with a 25% by weight dimethylformamide aqueous solution. The nonwoven fabric impregnated with polyurethane was produced by washing with water at 70 ° C. several times.

  Subsequently, the nonwoven fabric impregnated with polyurethane was treated with a 10% by weight aqueous caustic soda solution at 100 ° C. to elute the copolymer polyester, which is a sea component, to leave only the island component, thereby producing an ultrafine nonwoven fabric.

  Subsequently, the surface of the ultra-thin nonwoven fabric was buffed using a sandpaper having a roughness of # 240, dyed with a high-pressure rapid dyeing machine using a disperse dye, fixed, washed and dried, and then a softener and an antistatic agent. The artificial leather was obtained after the treatment.

Example 2

  An artificial leather was produced in the same manner as in Example 1 except that polybutylene terephthalate was used as an island component instead of polytrimethylene terephthalate to produce the second composite fiber.

Example 3

  An artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced so that the contents of the first conjugate fiber and the second conjugate fiber were 70% by weight and 30% by weight, respectively.

Example 4

  An artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced so that the contents of the first conjugate fiber and the second conjugate fiber were 50% by weight and 50% by weight, respectively.

Example 5

  An artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced so that the contents of the first conjugate fiber and the second conjugate fiber were 30% by weight and 70% by weight, respectively.

Example 6

  An artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced so that the contents of the first conjugate fiber and the second conjugate fiber were 10% by weight and 90% by weight, respectively.

Example 7

  In addition to the first and second composite fibers, a third composite fiber containing 70% by weight of polybutylene terephthalate (island component) and 30% by weight of a copolyester (sea component) is further used. Artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced so that the content of each of the first to third composite fibers was 90%, 5%, and 5%.

Example 8

  Artificial leather was produced in the same manner as in Example 7 except that the nonwoven fabric was produced so that the contents of the first to third composite fibers were 50%, 25%, and 25%, respectively.

Example 9

  Artificial leather was produced in the same manner as in Example 7 except that the nonwoven fabric was produced so that the contents of the first to third composite fibers were 10%, 60%, and 30%, respectively.

Example 10

  Artificial leather was produced in the same manner as in Example 7 except that the nonwoven fabric was produced so that the contents of the first to third composite fibers were 10%, 30%, and 60%, respectively.

Comparative Example 1

  Artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced using only the first conjugate fiber without using the second conjugate fiber.

Comparative Example 2

  Artificial leather was produced in the same manner as in Example 1 except that the nonwoven fabric was produced using only the second conjugate fiber without using the first conjugate fiber.

  The elastic recovery rate, texture, surface tactile sensation, frictional properties, and compressive elasticity (compression rate and recovery rate) of the artificial leather manufactured according to each of the examples and comparative examples were respectively measured by the following methods, and the results are shown in Table 3. Indicated.

Elastic recovery rate (%)

A sample displaying a distance of 200 mm was mounted on a tensile tester with a clamp interval of 250 mm, and stretched to 10% elongation at a speed of 50 mm / min and left for 1 minute.
Next, the load was removed at the same speed as the pulling speed, and the sample was left for 3 minutes, and then the actual distance x of the initially displayed distance was measured, and the elastic recovery rate was calculated by the following equation.

  Elastic recovery rate (%) = [(200−x) / 200] × 100

Texture

  In order to measure the texture of artificial leather, an evaluation team consisting of 5 experts was formed. A sensory test was performed on the three items of flexibility, volume feeling, and bending characteristics, and each was evaluated on a 6-point scale from 0 to 5 points (5 points: best). After summing up the scores for each item, all the sums given by five experts were summed up and evaluated as shown in Table 1.

Surface feel

  In order to measure the tactile sensation of the artificial leather surface, an evaluation team consisting of five experts was constructed. The softness of the surface was evaluated on a 6-point scale with 0 to 5 points (5 points: best). The scores given by five experts were added together and evaluated as shown in Table 2.

Friction characteristics

  The friction characteristic was evaluated by measuring the friction coefficient in the forward direction (fluff direction) and the reverse direction of the surface of the artificial leather, and evaluating the difference. The measuring method is as follows.

  The friction coefficient in the forward direction, which is the same direction as the napping direction of the fluff, and the friction coefficient in the direction opposite to the napping direction of the fuzz were measured using a friction tester manufactured by Toyo Seiki Co., Ltd. The same specimen was used for the upper friction material and the lower friction material, and the upper friction material was installed so that the fluff direction was opposite to the movement direction of the friction tester. On the other hand, the lower friction material is attached so that the direction of motion of the friction tester and the direction of fluff are the same when measuring the forward friction coefficient, and the direction of motion of the friction tester when measuring the reverse friction coefficient. And the fluffs were attached so that their directions were opposite to each other.

  The moving distance of the lower friction material, which is the friction material, is about 20 cm, the weight is 200 g, the load cell is 1 kg, the chart scale is X1, and each friction coefficient is measured three times. After that, the final friction coefficient was obtained by taking the average of these measured values.

  As the value of the friction coefficient, a value indicating the maximum static friction force is used.

  Using the friction coefficient values thus measured, the friction characteristics were obtained by taking the absolute value of the difference between the forward friction coefficient and the reverse friction coefficient.

  Friction characteristics = | Friction coefficient−Reverse friction coefficient |

Compression elasticity

Since the compression elasticity (thickness direction) of artificial leather can be grasped by compressibility and restoration rate, VMS of G & P Technology
The compression rate and restoration rate of artificial leather were measured using a PV-Series apparatus.

A circular indenter was subjected to an initial load of 900 gf / cm ² and maintained for 30 seconds. And the maximum thickness (T1) of the artificial leather when 30 seconds passed after removing the initial load was measured in units of 1/1000 mm. After the initial load was again applied for 30 seconds, the minimum thickness value (T2) was measured in units of 1/1000 mm. Then, when the initial load was removed and 30 seconds passed, the thickness (T3) of the artificial leather was measured in units of 1/1000 mm. And the compression rate and the decompression | restoration rate were calculated using the following Formula, respectively.

  Compression rate (%) = [(T1-T2) / T1] × 100

  Restoration rate (%) = [(T3-T2) / (T1-T2)] × 100

Claims (15)

A non-woven fabric comprising short fibers having a fineness of 0.001 to 0.5 denier;
A polymer elastic body impregnated inside the nonwoven fabric,
The artificial leather, wherein the short fibers are two or more kinds of polyester short fibers having a repeating unit of —CH ₂ —, and the number of the repeating units is different from each other.   The artificial leather according to claim 1, wherein the two or more kinds of polyester-based short fibers each have 2 to 4 repeating units.   The artificial leather according to claim 1, wherein the nonwoven fabric contains 5 to 95% by weight of polyethylene terephthalate short fibers.   2. The artificial leather according to claim 1, wherein the nonwoven fabric has a weight variation coefficient of 20% or less. The two or more polyester short fibers have different elastic recovery rates at 20% elongation,
2. The artificial leather according to claim 1, wherein the ratio of the minimum value to the maximum value of the elastic recovery rate at 20% elongation of the two or more kinds of polyester short fibers is 10 to 80%.   The artificial leather according to claim 1, wherein the two or more kinds of polyester short fibers have a length of 5 to 100 mm.   2. The artificial leather according to claim 1, wherein the artificial leather has an elastic recovery rate of 80% or more at 10% elongation.   The artificial leather according to claim 1, wherein a difference in friction coefficient between the artificial leather and the direction parallel to the fluff direction of the artificial leather is 0.30 or less.   The artificial leather according to claim 1, wherein the artificial leather has a compression rate of 8 to 50%.   The artificial leather according to claim 1, wherein the artificial leather has a restoration rate of 80% or more. Step of preparing two or more types of sea-island type composite fibers containing sea component and island component (wherein the island components of the two or more types of sea-island type composite fibers have a repeating unit of —CH ₂ — Are different polyester polymers).
Forming a nonwoven fabric with the two or more sea-island composite fibers;
And a step of eluting sea components of the two or more types of sea-island composite fibers to form an ultrafine nonwoven fabric.   The method for producing artificial leather according to claim 11, further comprising a step of impregnating the nonwoven fabric with a polymer elastic body before forming the ultrafine nonwoven fabric.   The method for producing artificial leather according to claim 11, further comprising a step of impregnating the ultrafine nonwoven fabric with a polymer elastic body. The step of forming the nonwoven fabric is performed using one or more methods of air raid method, paper making method and carding / cross wrapping method,
The artificial fabric according to claim 11, wherein the step of forming the nonwoven fabric includes a step of uniformly mixing the two or more kinds of sea-island type composite fibers so that the nonwoven fabric has a weight variation coefficient of 20% or less. A method of manufacturing leather. The method for producing artificial leather according to claim 11, wherein the nonwoven fabric has a unit weight of 100 to 700 g / m ² .