KR102405906B1 - Manufacturing method of artificial leather - Google Patents

Abstract

the present invention A method for manufacturing artificial leather, which has a luxurious appearance and soft feel and excellent mechanical strength by partially pre-eluted before impregnating a nonwoven fabric with an elastic polymer it's about how

Description

Manufacturing method of artificial leather

the present invention The present invention relates to a method for manufacturing artificial leather, wherein the nonwoven fabric is partially pre-eluted before impregnating a polymer elastic body, so that the surface layer and the back layer of the artificial leather have a luxurious appearance and a soft feel. will be.

The conventional manufacturing method of non-woven artificial leather generally uses sea-island microfibers to form a non-woven fabric through a non-woven fabric manufacturing process such as needle punching, and after providing an elastic polymer, the sea component is eluted using an appropriate solvent to achieve micro-fineness. Then, the artificial leather is manufactured by forming surface napping, dyeing it in a desired color, and post-processing.

In the case of using such a manufacturing technique, there is a limit in improving the density of the island component by first fixing the nonwoven fabric made of the island-in-the-sea yarn by an elastic polymer, so there is a limit in forming a luxurious appearance and a soft feel.

Therefore, in order to improve the density of the nonwoven fabric, a method of increasing the density of the nonwoven fabric through heat shrinkage under hot water and steam after manufacturing the nonwoven fabric is utilized. have.

In order to solve this limitation, the method of increasing the density between island components by conducting the sea component elution process first before applying the elastic polymer is being applied. In order to prevent this, it is necessary to pre-process the size. In addition, since many direct adhesive structures are formed between the elastic polymer and the island component, mechanical properties are increased, but there is a problem in that flexibility or soft touch may be impaired in the emotional part.

Republic of Korea Patent Publication No. 0475542 (Title of the invention: manufacturing method of ultra-microfiber non-woven artificial leather)

In order to solve the above problems, the present invention improves the dissolution method of sea components in the manufacturing process of artificial leather, and provides a method for manufacturing artificial leather that has excellent shape stability that does not cause deformation, and that does not decrease soft feel and flexibility. intended to provide

In order to solve the above problems, the present invention provides a method for manufacturing artificial leather, comprising the steps of: composite spinning of sea-island fibers; manufacturing a nonwoven fabric using the sea-island fiber; a pre-eluting step of applying and permeating an eluate for dissolving the sea component of the sea-island fiber on one side of the nonwoven fabric to elute the sea component; Nonwoven heat shrinking step of heat shrinking the nonwoven fabric in a steam box after the pre-eluting step; an impregnation step of impregnating the nonwoven fabric with an elastic polymer after the nonwoven heat shrink step; a residual sea component elution step of eluting the undissolved sea component of the nonwoven fabric with an eluate after the impregnation step; and forming napping by buffing the surface of the surface layer using the surface on which the pre-elution is made after the step of elution of the remaining sea component as a surface layer.

According to the present invention, since the shape of the nonwoven fabric is stably maintained by the remaining unextruded part by dissolving the line portion during the manufacturing process of the artificial leather, sizing treatment is not required for the nonwoven fabric after the line elution.

According to the present invention, the density of island component fibers is maximized in the surface layer pre-eluted during the manufacturing process of artificial leather, and the high-quality appearance, flexibility and soft touch are obtained due to the increase in surface napped density, and the polymer elastic body and the eluted island component It is possible to manufacture artificial leather with improved mechanical properties due to the partial adhesive structure of the fibers.

Hereinafter, the manufacturing method of the artificial leather of the present invention will be described in detail.

The present invention relates to a method for manufacturing artificial leather, wherein a sea-island type fiber is manufactured through a composite spinning process, a nonwoven fabric is manufactured using the island type fiber, and a part of the sea component of the nonwoven fabric is partially linearly eluted. and impregnating the pre-eluted nonwoven fabric with an elastic polymer, and eluting the sea component again.

The process of manufacturing the island-in-the-sea fibers is a process of composite spinning using a first polymer of a sea component dissolved in a solvent and eluted with a solvent and a second polymer of an island component remaining insoluble in the solvent. include

The first polymer of the sea component may be made of co-polyester, polystyrene or polyethylene, and preferably co-polyester having excellent solubility in an alkaline solvent.

The second polymer of the island component may be made of nylon or polyester that is not soluble in an alkali solvent and can be dyed with a disperse dye, and specifically, polyethylene terephthalate, polyoxyethylene benzoate, polybutylene tere and phthalate, polytrimethylene terephthalate, polyamide, polyacryl, polyvinyl alcohol, polytriethylene terephthalate, and acetate.

The process of manufacturing the nonwoven fabric includes a process of stacking and forming a plurality of webs through a carding process and a crosslapping process on the island-in-the-sea fibers in a staple state, and a needle penetrating the formed web It includes a needle punching process of needle punching so that the density becomes 2000-2400 ppsc.

Before immersing the nonwoven fabric in the polymer elastomer impregnating solution, a pre-eluting step of coating the nonwoven fabric so that an eluent such as an aqueous solution of caustic soda can penetrate from one side of the nonwoven fabric to a thickness ranging from 5 to 70% of the total thickness of the nonwoven fabric. .

At this time, as a coating method, knife coating, roll coating, gravure coating, slot die coating, spray coating, etc. can be used, but in order to prevent the immersion of the eluate inside the nonwoven fabric due to its own weight and accurate application of the eluent, it is better to use the gravure coating. more advantageous

On the other hand, the concentration of the aqueous caustic soda solution as the eluent is preferably 6 to 15% by weight. If the concentration is less than 6% by weight, the dissolution rate is too low and the time to complete dissolution becomes too long, depending on the weight of the nonwoven fabric. It is undesirable because dissolution may not be made to a desired site, and when it exceeds 15 wt%, dissolution occurs rapidly and may infringe even island components, which is not preferable.

After the pre-eluting step, inducing the nonwoven fabric impregnated with the eluate to a steam box to heat shrink the nonwoven fabric at a temperature of 40 to 120 ° C, preferably 60 to 100 ° C, for 1 to 10 minutes, preferably 3 to 8 minutes A nonwoven fabric heat shrink step may be performed.

In the heat contraction step, when the temperature is lower than the lower limit of the range, the dissolution rate is lowered, and when it is high, the energy cost becomes excessive, which is undesirable. Without this, complete dissolution is possible.

In the heat shrinking step, the dissolution of the sea component in the portion permeated with the eluate occurs at the same time, and in the portion where the elution occurs, the adjacent distance between the island components becomes close together with the shrinkage, thereby maximizing the fiber density.

The nonwoven fabric divided into a dissolution surface layer part, where the fiber density is maximized due to elution and shrinkage of the part infiltrated with the eluent, and a back layer part, which is not, then forms a gradient of fiber density. The content of the polymer elastomer is also partially different. That is, the content of the elastic polymer is decreased in the surface layer portion having a high fiber density, and the content of the elastic polymer is increased in the back layer portion having a low fiber density.

The non-woven fabric, which has undergone the pre-eluting and non-woven heat shrink steps, still has a non-extruded portion as a back layer, thereby maintaining shape stability against mechanical tension.

After the heat shrinking step of the nonwoven fabric, the remaining sea component may be eluted by impregnating the nonwoven fabric with an elastic polymer, coagulating, washing with water, and eluting with an eluent such as an aqueous caustic soda solution.

In this case, it is preferable that the concentration of the aqueous solution of caustic soda is 1 to 5% by weight, which is lower than the concentration of the aqueous solution of caustic soda in the step of pre-eluting, as it does not infringe on the ultrafine fibers of the surface layer formed in the step of pre-elution and heat shrink of the nonwoven fabric.

Thereafter, using sandpaper, a pre-eluted portion having a high fiber density is used as a surface layer, and the surface of the surface layer is buffed to form brushing, and artificial leather can be manufactured through dyeing and post-processing.

In the case of the artificial leather prepared in this way, the napped density of the surface layer of the buffed pre-eluted portion is high, so the appearance quality is excellent, and the Since the content of the elastic polymer in the surface layer is significantly reduced, it is possible to remarkably solve various problems of lowering fastness caused by residual dyes present in the elastic polymer after dyeing.

In addition, the portion of the back layer in which a large amount of the elastic polymer, which is not relatively pre-eluted, is distributed, has elastic properties, and at the same time, the direct adhesive structure between the elastic polymer and the island component can be resolved, thereby expressing a flexible and soft feel.

Hereinafter, the present invention will be described in more detail based on the following Examples and Comparative Examples.

However, the following examples are only for illustrating the present invention, and the present invention is not limited by the following examples, and can be substituted and changed to other equivalent examples without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains.

[Example 1]

Using polyester as an island component and copolyester as a sea component, composite spinning is performed so that the island component:sea component has a weight ratio of 70:30. After performing a crimping process as much as possible, heat setting at 130° C., and cutting to 51 mm to prepare islands-in-the-sea short fibers.

A nonwoven fabric having a weight per unit area of 500 g/m 2 and an apparent density of 0.230 g/cm 3 was prepared by forming a web using the island-in-the-sea short fibers through a carding process and a cross lapping process and then performing needle punching.

Then, the nonwoven fabric is coated with an aqueous solution of caustic soda with a concentration of 10% by weight using a gravure coating machine so that the aqueous solution of caustic soda can penetrate up to 50% of the thickness of the nonwoven fabric on one side of the nonwoven fabric, and immediately at a temperature and relative humidity of 100 ° C. One side treated with aqueous caustic soda solution by pre-elution pre-treatment for 2 minutes in a high-temperature steam dissolving machine under 98% condition was micro-fine due to the elution of sea components, and at the same time, high shrinkage was expressed to form a high-density ultra-fine non-woven fabric layer, On the other side, a double structure nonwoven fabric was formed in the form of a non-extruded, high shrinkage nonwoven fabric.

The thus-obtained double-structured nonwoven fabric was immersed in a polyurethane polymer elastomer solution at a concentration of 10 wt% and 25 °C obtained by dissolving polyurethane in a dimethylformamide (DMF) solvent, and using an aqueous solution of dimethylformamide with a concentration of 15 wt% By coagulating the urethane and then washing with water, the shrink cloth was impregnated with polyurethane.

Then, the polyurethane-impregnated shrink fabric is treated with an aqueous solution of caustic soda with a concentration of 5% by weight to completely elute the sea component of the back layer of the dual structure non-woven fabric where the residual sea component remains, and only polyester, which is an island component, is used over the entire nonwoven fabric. miniaturized to remain.

Then, brushing is formed on the surface by buffing the pre-eluted surface using roughness #150 and #300 sandpaper. The artificial leather was manufactured by processing.

[Example 2]

Artificial leather was manufactured in the same manner as in Example 1, except that in Example 1, the caustic soda solution was applied to a thickness of 10% of the thickness of the nonwoven fabric during the pre-eluting treatment.

[Example 3]

An artificial leather was prepared in the same manner as in Example 1, except that in Example 1, the caustic soda aqueous solution was applied to a thickness of 70% of the thickness of the nonwoven fabric during the pre-eluting treatment.

[Comparative Example 1]

An artificial leather was prepared in the same manner as in Example 1, except that the pre-eluting treatment was not performed in Example 1.

[Comparative Example 2]

Artificial leather was manufactured using the same method as in Example 1, except that in Example 1, the caustic soda aqueous solution was applied to penetrate up to 4% of the thickness of the nonwoven fabric during the pre-eluting treatment. .

[Comparative Example 3]

Artificial leather was manufactured in the same manner as in Example 1, except that in Example 1, the caustic soda aqueous solution was applied to penetrate up to 80% of the thickness of the nonwoven fabric during the pre-eluting treatment.

[Comparative Example 4]

Artificial leather was manufactured in the same manner as in Example 1, except that in Example 1, when the sea component of the back layer was completely eluted, it was treated with an aqueous solution of caustic soda having a concentration of 10% by weight.

The physical properties of the artificial leathers prepared in Examples and Comparative Examples were measured by the following evaluation method, and the results are shown in Table 4.

<Evaluation method>

1. Apparent Density

After slicing the surface layer (pre-eluted layer) and back layer of artificial leather using a slicing machine, each unit weight is measured according to JIS L 1096 8. 4. 2 (1999), and the thickness is measured with a dial thickness gauge. (manufactured by Ozaki Seisakuso Co., Ltd., trade name “Picoque H”).

Thereafter, the artificial leather of each surface layer and the back layer was immersed in a dimethylformaldehyde (DMF) solution at a temperature of 60° C. for 24 hours to extract all the polyurethane components inside the artificial leather, washed with water and dried to determine the weight of the nonwoven fabric alone Measure in the same way as the unit weight measurement method.

The apparent density of each layer is obtained by calculation from the measured thickness of the surface layer and the back layer measured previously and the unit weight value of the nonwoven fabric alone of the surface layer and the back layer after polyurethane extraction.

2. Tensile strength and elongation at break

After cutting 5 sheets of artificial leather fabric in the horizontal and vertical directions according to the standard, measure the tensile strength and elongation at break according to ASTM D 5035 of the American Society for Testing and Materials using a tensile tester, and take the average value.

3. Tear strength

After cutting 5 sheets of artificial leather fabric in the horizontal and vertical directions according to the standard, measure the tear strength according to ASTM D 2261 of the American Society for Testing and Materials using a tensile tester and take the average value.

4. Length elongation (%)

During the artificial leather manufacturing process, the length of the first nonwoven fabric is measured after the nonwoven fabric is manufactured and before the tanning process (L1), and the total length (L2) after the tanning process is completed, and calculated using the following formula.

Length elongation (%) = ((L2 - L1) / L1) x 100

5. Artificial leather exterior quality

An evaluation team consisting of 5 experts conducts a sensory test on five items: uniformity of nap and color, wrinkles, see-through, bulkiness, and sense of quality.

Each expert evaluates each item in units of 1 point, and gives 0 to 5 points (5 points: best). save Then, it evaluates according to the criteria of Table 1 below.

total score Appearance quality evaluation 0 to 25 very bad 26 to 50 bad 51 to 75 usually 76 to 100 Great 101 to 125 very good

6. Texture of artificial leather

An evaluation group of 5 experts conducts sensory tests on the items of flexibility, fullness, and bendability.

Each expert evaluates each item in units of 1 point, giving 0 to 5 points (5 points: best), adding up the scores for each item by expert, and then adding up the scores of 5 experts again to obtain a total score .

total score texture evaluation 0 to 15 very bad 16 to 30 bad 31 to 45 usually 46 to 60 Great 61 to 75 very good

7. The surface feel of artificial leather

The evaluation team is composed of 5 experts. Each expert evaluated the softness of the artificial leather surface in units of 1 point and gave 0 to 5 points (5 points: best), and the total score is obtained by adding up the scores of 5 experts.

total score texture evaluation 0 to 5 very bad 6 to 10 bad 11 to 15 usually 16 to 20 Great 21 to 25 very good

Characteristics of artificial leather division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 surface layer apparent
Density (g/cm3) 0.375 0.320 0.360 0.220 0.235 0.280 0.365 Back Layer Appearance
Density (g/cm3) 0.280 0.275 0.265 0.225 0.165 0.245 0.265 The tensile strength
(kgf/cm) width 7.5 6.9 6.5 4.2 4.5 5.0 4.5 Vertical 8.3 7.3 7.0 4.5 4.8 5.5 5.0 break elongation
(%) width 103 105 95 55 60 85 80 Vertical 83 85 75 50 52 75 73 tear strength
(kgf) width 4.5 3.7 3.5 2.5 2.5 2.0 2.0 Vertical 5.7 5.0 4.2 2.5 2.7 2.5 2.5 Length elongation (%) 8 7 10 6 6 12 10 appearance quality very good very good very good bad bad usually usually texture Great Great Great usually bad bad usually surface feel very good Great very good bad bad usually usually

From the examples in Table 4 above, it was confirmed that a difference in fiber density was generated between the surface layer and the back layer of the artificial leather that had been partially pre-eluted to the nonwoven fabric during the manufacture of artificial leather, and the apparent density of the surface layer was increased. On the other hand, it was confirmed that the difference in fiber density between the surface layer and the back layer did not occur or was very insignificant when the non-woven fabric was not pre-eluted or when the non-woven fabric had a thickness of up to 80%.

In addition, due to this, the artificial leather according to the embodiment according to the present invention was evaluated to be superior to the artificial leather according to the comparative example in all evaluation items such as mechanical properties, appearance quality, texture, and surface feel. It can be confirmed that the quality of artificial leather is improved by partial pre-eluting.

Claims (4)

In the manufacturing method of artificial leather,
composite spinning of sea-island fibers;
manufacturing a nonwoven fabric using the sea-island fiber;
a pre-eluting step of applying and permeating an eluate for dissolving the sea component of the sea-island fiber on one side of the nonwoven fabric to elute the sea component;
Nonwoven heat shrinking step of heat shrinking the nonwoven fabric in a steam box after the pre-eluting step;
an impregnation step of impregnating the nonwoven fabric with an elastic polymer after the heat shrinking step of the nonwoven fabric;
a residual sea component elution step of eluting the undissolved sea component of the nonwoven fabric with an eluate after the impregnation step; and
After the step of elution of the residual sea component, the surface on which the pre-elution is made is used as a surface layer, and the surface of the surface layer is buffed to form napping;
including,
The method of manufacturing artificial leather, characterized in that the penetration of the eluate in the pre-eluting step is in the range of 5 to 70% of the total thickness of the nonwoven fabric. delete The method of claim 1,
The eluate is an aqueous solution of caustic soda, the concentration of the aqueous solution of caustic soda in the pre-elution step is 6 to 15% by weight, and the concentration of the aqueous solution of caustic soda in the step of elution of the remaining sea component is 1 to 5% by weight, characterized in that A method for manufacturing artificial leather. It is manufactured by the method of any one of claims 1 to 3, and the length elongation ratio (the ratio of the difference between the length of the first nonwoven fabric before the tanning process (L1) and the length of the nonwoven fabric after the tanning process is completed (L2)) Artificial leather with 7 to 12% of this.