KR101609662B1 - Split leather of sponge type and manufacturing method thereof - Google Patents

Abstract

More particularly, the present invention relates to a method of manufacturing a sponge-like surface skin of the present invention, which comprises a buffing step of polishing the surface of a skin of a surface of a skin through a tanning process; A wet coating step of wet-coating a polyurethane resin coating solution on one side of the ground abrasive leather; A desolvation process in which the wet coated skin is drained using a spray system; An aging step of moving the desolvated skins to a coagulating bath to solidify the coating liquid; A baking process for vacuum drying the hardened leather in which the coating liquid is solidified; A drying step of drying the vacuum dried skins; And a coating step of coating the dried cowhide leather.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sponge-

More particularly, the present invention relates to a sponge type six-piece leather and a method of manufacturing the same, and more particularly to a sponge type leather and a method of manufacturing the same, The present invention relates to a process for producing a leather which comprises the steps of: applying a wet process to a leather to form a leather, wherein the leather is coated with a porous polyurethane resin layer on the leather, To a sponge-like flesh-like leather which can be used as a natural leather case of an electronic device such as a smart phone, a tablet PC, etc., and a method for manufacturing the same, using not only the physical strength such as impact resistance .

The smartphone case can be divided into three types: a flip-type case made of leather, a hard case made of plastic, and a jelly case made of silicone or urethane. In particular, the flip-type case made of natural leather protects the smartphone on both sides, it can cover the front face so that the liquid crystal does not become dirty, and can protect the expensive smart phone from the external impact, have. However, most cases of smartphone cases using leather materials domestically are manufactured using high quality raw material (F / G, Full Grain), which is very expensive. In recent years, the move to develop a smart phone case using low-grade raw skins (split leather) has been gradually expanding, mainly due to rising prices for raw materials.

Generally, leather of cowhide or other large animal is thick, so it is separated into two layers or three layers. According to these layers, the leather is made of leather with silver hair (grain) It is divided into the skin side (Flesh side) which is separated from the skin (splits, tops). Silver leather is excellent in stretch and abrasion resistance, and is mainly used for clothing materials. The slim leather is thin and torn to be used in various articles such as shoes, handbags and the like. Particularly, in the case of a smartphone case, it is common to use silver leather because it requires physical properties equal to or greater than those of the above clothes.

In the case of the skins, which are evaluated as low-quality raw hides, the leather is processed with the epithelium of the lower layer when it is divided into two layers in the process of avoiding hair loss of raw material, Since it is inferior in strength and strength in terms of quality and physical properties, it has a very low commercial value as various leather materials, and has been used only very limitedly, for example, in shoes and some materials.

In order to realize the silver layer on the skin of the sole, the action leather which is applied to the skin by applying the resin to the release paper in Korea is most commonly used, but the silver surface formation by the dry method is the film thickness Is very thin, and there are many problems such as unevenness of surface roughness, unevenness of protruded bristles, and fastness of dyeing fastness.

Therefore, when used as cover sheets for tablet PCs and smartphone cases such as high-quality leather, silver leather is a very luxurious material, but it has a disadvantage in that it is expensive. Therefore, development of natural leather using low- It is urgently required.

Accordingly, the present inventors have made efforts to produce a sponge-type natural leather at the same time as using a low-cost, high-price competitive leather cowhide leather as compared to an expensive raw leather cowhide leather. As a result, natural leather including preparatory, oil-based, neutralized, re-oiled, branched, buffing and wet coating steps is prepared by using a hexahedron which is divided from napi and relatively low in unit cost compared to silver hide, It has been found that impact resistance, soft touch, and the like are improved by coating a porous polyurethane resin layer on the skins of skins, neutralization, re-oiling, branches, and buffing steps.

Accordingly, an object of the present invention is to provide a sponge-like surface leather excellent in price competitiveness.

Another object of the present invention is to provide a method for manufacturing a sponge-like surface skin improved in impact resistance and touch.

Another object of the present invention is to provide a smartphone natural leather case using the above-mentioned sponge-like skin.

The present invention provides a sponge-like cured leather characterized in that a porous polyurethane resin layer is formed on one side of a cowhide leather and comprises a urethane resin and wood powder.

The present invention also relates to a buffing process for polishing the surface of a skin of a skin through a tanning process; A wet coating step of wet-coating a polyurethane resin coating solution on one side of the ground abrasive leather; A desolvation process in which the wet coated skin is drained using a spray system; An aging step of moving the desolvated skins to a coagulating bath to solidify the coating liquid; A baking process for vacuum drying the hardened leather in which the coating liquid is solidified; A drying step of drying the vacuum dried skins; And a coating step of coating the dried cowhide leather. The present invention also provides a method of manufacturing a sponge-like cowhide leather.

The present invention also provides a smartphone natural leather case using the above-described sponge-like skin.

The sponge-like skin according to the present invention has the following advantages.

1) It is possible to secure price competitiveness by using cheap skin leather compared to expensive silver leather, and it is possible to manufacture environmentally friendly sponge type slim leather by desolvation.

2) A porous polyurethane resin layer is coated on the skin prepared by the preparatory, neutralization, re-oiling and branch buffing steps to form a porous film, thereby giving a soft touch to the leather and improving the physical strength such as impact resistance .

3) It can be used as a natural leather case for electronic devices such as smart phones and tablet PCs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view schematically showing a method of manufacturing a sponge-like surface leather according to the present invention.
2 is a SEM photograph showing a cross-section of a sponge-type slim leather according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to one embodiment.

The present invention includes a sponge-like surface leather characterized in that a porous polyurethane resin layer is formed on one side of a cowhide leather and comprises a urethane resin and wood powder. The above-mentioned six-sided leather can be produced by a preparation process, an oil process, a neutralization process, a remelting process, a branch process and a drying process.

The preparation process is divided into demineralization and pickling, and demineralization is a process for removing lime added for alkalization in the preparation process, and pickling is a process for acidifying the leather by hydrolysis of an acid using salt and acid, The oily process is a process for uniformly introducing the tanning agent. In addition, tanning is a process that imparts mineral properties to animal products for commercialization of leather, which can impart heat resistance and flexibility.

In addition, the neutralization process is a process for raising the pH so that penetration of the dye, shin and oil components is easy. Generally, low-density tissues are dried by chromium tanning only because of the relatively loose texture of the flax oil in the abdomen of animal hides. The remineralization process is usually a process for imparting fullness and proper touch to leather by using a synthetic tanning agent, and promoting the penetration of the branching agent and the dye. The branching process is a process for putting a retentate in between the fibers or fibers of the leather to impart flexibility and elasticity to the leather by acting as a lubricant between the fibers, This is a process for maintaining the moisture state. At this time, the surface treatment can be performed by using organic silicate such as acrylic and a binder which are binders in order to prevent separation of the wet coating layer and the leather and to increase the adhesion.

The polyurethane resin layer may be wet-coated with a polyurethane resin coating liquid containing 40 to 60% by weight of a urethane resin, 5 to 20% by weight of wood powder, 0.1 to 5% by weight of an additive and 30 to 50% by weight of a solvent. The urethane resin may be one-component urethane resin. When the content is less than 40% by weight, the viscosity is low and it can not be applied to leather. When the content is more than 60% by weight, viscosity is high and it may be difficult to apply to leather.

Wood flour and silica may be used as fillers for preventing the shrinkage of the above-mentioned skins. Specifically, when the wood powder content is less than 5% by weight, the filling effect is lowered and the paintability of leather is poor. When the wood powder content is more than 20% by weight, the solvent is not sufficiently formed due to hygroscopicity, And the wet friction fastness may be lowered.

The additive may be at least one selected from the group consisting of organic silicon (Silicone), isoparaffine, and polyether. The solvent may be selected from the group consisting of dimethylformamide (DMF), dimethylsulfoxide (DMSO) ) Or a mixture of the two.

The polyurethane resin layer may preferably have a thickness of 250 to 400 mu m. Specifically, when the thickness of the polyurethane resin layer is thinner than 250 탆, the impact resistance is weak as a cellular phone case material, and when the thickness is thicker than 400 탆, the adhesion to leather is lowered and the coating layer can be separated. The thickness is preferably 300 to 350 占 퐉.

The polyurethane resin layer may have a porous size of 10 to 50 mu m in diameter. Specifically, if the porosity is smaller than 10 탆 in diameter, impact resistance may be weak as a material for a mobile phone, and if it is larger than 50 탆, dyeing friction and sweat fastness may be lowered. The sponge-like cured leather having such a porous polyurethane resin layer can impart impact resistance and soft touch to the cured leather by the formed porous coating.

The present invention also relates to a buffing process for polishing the surface of a skin of a skin through a tanning process; A wet coating step of wet-coating a polyurethane resin coating solution on one side of the ground abrasive leather; A desolvation process in which the wet coated skin is drained using a spray system (200 ml / sec, leather is 20 SF); An aging step of moving the desolvated skins to a coagulating bath to solidify the coating liquid; A baking process for vacuum drying the hardened leather in which the coating liquid is solidified; A drying step of drying the vacuum dried skins; And a coating step of coating the dried cowhide leather. The present invention also provides a method of manufacturing a sponge-like cowhide leather. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view schematically showing a method of manufacturing a sponge-like surface leather according to the present invention.

In the buffing step, sandpaper of # 240 to # 320 can be used. The buffing process is a step of polishing the surface of the slim leather with a sand paper to impart smoothness of the leather before the wet coating process. Here, the sandpaper used for industrial purposes is No. The lower the number is, the thicker the particles are, the rougher the surface during working, and the higher the number, the more the surface becomes thicker. It shows a fine and fine shape. Specifically, sandpaper having a number lower than # 240 may have a rough surface of the leather, and sandpaper having a number higher than # 320 may not be polished at the time of a buffing process. Preferably, the buffing step is carried out in two steps of primary polishing using sandpaper # 240 and secondary polishing using sandpaper # 320.

In the wet coating process, the polyurethane resin coating liquid may be wet-coated to a thickness of 250 to 400 탆 by using a leather fabric wet coating apparatus. Specifically, the leather-like wet coating apparatus (Korea registration number: 10-1151279) is a coating apparatus which can easily coat a polyurethane resin coating liquid and easily remove a contaminated coating liquid, .

In the wet coating process, the porosity size can be adjusted according to the intended use. In the case of textile process, it can be controlled according to the solvent concentration in the coagulation tank. However, in the case of the leather process, the fabric is circulated like a fiber process and the size of the porosity can be controlled by the additive content. Specifically, a low hydrophilic lipophilic balance (HLB) additive reduces the intermolecular cohesion of the polymer, thereby forming a dense microporous film. On the other hand, in the case of an additive having a high HLB, it is possible to form a macroporous film. In the present invention, it is preferable to use an additive having a high HLB capable of forming a macroporous coating.

The polyurethane resin coating solution may contain 40 to 60% by weight of a urethane resin, 5 to 20% by weight of wood powder, 0.1 to 5% by weight of an additive and 30 to 50% by weight of a solvent. Here, the additive may use organosilicon (DS 700) as an additive having a high HLB. Specifically, 1% by weight of isoparaffin (DS800) and polyether (DS 600) are added to the total polyurethane resin coating solution to aid in the formation of a microporous film, and the organosilicon, which forms a macroporous coating, 1.5% by weight may be added. If the content of the organosilicon is less than 0.5% by weight, a microporous coating may be formed. If the content of the organosilicon is more than 1.5% by weight, sweat fastness and rubbing fastness may be lowered.

In the aging step in which the desolvated skins are transferred to a coagulation bath to solidify the coating liquid, desolvation is preferably performed using water in the coagulation bath, preferably 5 to 7 hours.

In the baking process, the baking is preferably performed at a temperature of 85 to 95 ° C for 300 to 350 sec under a vacuum pressure of 0.05 to 0.1 atm.

The present invention also includes a smartphone natural leather case using the above-mentioned sponge-like skin.

The sponge-like slim leather according to the present invention can provide price competitiveness by using inexpensive slim leather as compared with expensive silver silk leather, and can produce environmentally friendly sponge-like slim leather by desolvation. Also, a porous polyurethane resin layer is coated on the pretreated leather by pretreatment using a leather fabric wet coating apparatus to give a soft touch to the leather and improve the physical strength such as impact resistance. This can be used as a natural leather case for electronic devices such as smart phones and tablet PCs.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Manufacturing Example: Manufacture of slim leather

The leather was produced in a conventional manner by a conventional tanning process shown in Table 1 below.

fair Chemical name content (%) Temperature (℃) Time (min) Remarks Termination
(Deliming) H ₂ O 150 30 60 yuan 2.0 Enzyme 0.3 pH: 8.6 Exhaust & Rinse Pickling
(Pickling) H ₂ O 80 30 20 Salt 8 Degreasing agent 0.2 antiseptic 0.1 Formic acid 0.5 20 Legacy 1.3 1/3 × 20 + 60 pH: 2.8 Stirring at night meteor
(Tanning) chrome 4 30 90 MgO 0.4 300 pH: 3.8 Night stirring → Discharge & rinsing → Dehydration → Thickness control wash
(Washing) H ₂ O 200 30 20 Formic acid 0.2 Degreasing agent 0.2 Exhaust & Rinse Rechrome
(Rechrome) H ₂ O 100 35 90 Freetan CR 2 chrome 2 BRTHON-D108 0.4 Exhaust & Rinse Neutralization
(Neutralize) H ₂ O 100 30 120 Freetan NC 2 Formic acid soda 2 NaHCO ₃ 2.5 pH: 6.5 Exhaust & Rinse Remastered
(Retanning)
&
Branch
(Fatliquoring) H ₂ O 100 45 90 CPR 3 MIMOSA 2 BRTA-D 2 Dye (Black TB) 2.5 PAM 3 Check dye penetration The sulfonation agent (SA) 5 90 pH: 3.4 to 3.6 Suboxide oxidation (CTS) 5 exhaust Pretreatment H ₂ O 100 40 10 Acrylic Shintan 3 bookbinder 3 30 Silicone touch agent 2 20 Formic acid 3 30 pH: 3.4 to 3.6 Exhaust & Rinse → Vacuum → Dry 50 ℃ → Vibration (3Step) Buffing Primary # 240, Secondary # 320 Enzyme: SOGO2YM1121, Sogo Corporation
Degreasing agent: BRTHON-D108, Brother
Preservatives: TB30L, Sogo Corporation
Chrome Shining: Freetan CR, Free Tech
Chinese Shintan: Freetan NC
Resin Synthetic Shins: BROTAN-CPR, Brother
Leveling agent: BRTA-D, Brother
Dyes: Black TB, TNT
Synthetic acrylic synthetics: PAM, Brother
Sulfonation agent: BROSOL-SA, Brother
Suboxides: CTS, Daeyoung Chemical
Binder: Binder 779 (Korea Precision)
Silicon Touch Agent: ADB (Jin-Young Chemical)

EXAMPLES: Manufacture of Sponge-type Skinskin

A buffing process was performed in which the surface of the leather of the above-prepared example was first polished with # 240 sandpaper, and then polished again with # 320 sandpaper. The polyurethane resin coating solution prepared by mixing the composition shown in the following Table 2 on one side of the above-ground abrasive leather was wet-coated to a thickness of 286 탆 and then subjected to desolvation treatment using a spraying device (200 ml / sec, leather 20SF) Respectively. Then, the desolvated skins were loaded in a coagulation bath for 6 hours to solidify the coating solution, and then vacuum dried at 90 DEG C for 300 seconds using a scraper. Subsequently, the dried skins were secondarily dried at a temperature of 40 DEG C for 200 minutes, and a sponge-like skinshaving a porous coating was produced through a vibration and coating process.

Item Content (% by weight) One-component urethane resin 50 Wood flour 16 Additive 1 DS700 1.5 Additive 2 DS800 0.5 Additive 3 DS600 0.5 Solvent (DMF) 31.5 One-component urethane resin: DU-1055U, Duksung Chemical solid content 40.0%
Wood powder: MS Tech
Additive 1: DS700, Duksung Chemical
Additive 2: DS800, Duksung Chemical
Additive 3: DS600, Duksung Chemical

Comparative Example 1

The wet coating was applied to the coating liquid composition shown in Table 2 without adding DS700 additive having a high HLb.

Comparative Example 2

The wet-coated skins were manufactured in the same manner as in the above Example but without performing the vacuum drying process using the skimmer.

Experimental Example 1: Evaluation of the environmental hazard of the skin leather produced in the above production example

In order to evaluate the environmental hazards of the slim leather produced in the above production example, the results were shown by the following methods as shown in Table 3 below.

Item unit Test Methods Fit range
(Spec) Manufacturing example Azo Dyes mg / kg KS K 0147: 2008 N.D. Not detected Formaldehyde mg / kg KS M ISO 17226: 2004 75 ↓ Not detected Hexavalent chromium mg / kg KS M ISO 17075: 2008 3 ↓ 2.8 Dimethyl fumarate mg / kg Safety quality standard Annex
3 5.2.4 / Confirmation of autonomous safety
Safety Standards Annex 4B 0.1 ↓ Not detected Chlorinated phenols mg / kg KS K 0733: 2007 5 ↓ Not detected

As shown in the above Table 3, the environmental hazards of the skins made by the above production examples were evaluated. Four hazardous substances such as Azo Dyes, formaldehyde, dimethyl fumarate and chlorinated phenols were not detected , Hexavalent chromium material was detected, but it was confirmed that the amount of the chromium material was detected at a level which does not significantly affect the environment.

Experimental Example 2-1: Evaluation of desolvation content in a coagulation bath with time using wet coated leather

In order to evaluate the desolvation content in the coagulation bath over time using the wet-coated skins according to the above production example, the wet coating was desolvated through a spray system (200 ml / sec, leather 20SF) and then transferred to the coagulation bath The coating solution was solidified. A leather sample was taken according to the time of loading in the coagulation bath and dried in a dry oven for 10 minutes and then the content of DMF was measured.

As a result, after wet coating, after moving to a coagulation tank (amount of water in the coagulation tank: 11 kg per one piece of leather (22SF) using a primary spray device), about 3,000 mg / kg of DMF Content was detected. It was confirmed that the retention time of the coagulation bath did not show a large change in the DMF content after 6 hours. In the case of a leather coated with a polyurethane resin coating liquid having a thickness of 250 μm or more, desolvation of the coating surface is required by using a spray device, and the residence time of the coagulation bath should be 6 hours or longer before the residual DMF is eluted.

EXPERIMENTAL EXAMPLE 2-2: Evaluation of desolvation content in the baking process with the use of wet-coated skins with temperature and time

In order to evaluate the desolvation content in the baking process according to the temperature and time using the pretreated skins prepared according to the above preparation example, the skins were desolvated in the coagulation bath, After that, the content of DMF in the dried skins was measured in a dry oven.

As a result, it was found that DMF content was about 650 ~ 1,200 mg / kg at a temperature lower than 90 ℃ and about 400 mg / kg at a temperature of 90 ℃. When the temperature was higher than 95 ℃, A phenomenon has occurred.

In addition, DMF content was measured to be 890 ~ 580mg / kg at a time slower than 300 sec, and thinning of leather belly at 350 sec.

As a result, it was confirmed that DMF content of the skins was reduced and the surface of the coating did not show any abnormality when the temperature was 90 ° C. and the time was 300 sec.

Experimental Example 3: Evaluation of physical properties and SEM measurement of the sponge-type skins made in the above Examples

In order to evaluate the physical properties of the sponge-like cured skins manufactured in the above-mentioned examples, the following methods were used as shown in Table 4, and the cross-section of the cured skins was measured by SEM. The results are shown in Fig.

Item unit Test Methods Fit range
(Spec) Example Coating thickness ㎛ KS M 6882: 2006 250 or more 286 The tensile strength kgf / mm ² KS M 6882: 2006 0.5 or more 1.0 Elongation rate % KS M 6882: 2006 70 or less 50 Phosphorus strength kgf / mm KS M 6882: 2006 4 or less 6.0 flexibility mm KS M ISO
17235 4 or more 4.7 Wear reduction mg ASTM D 3884 Below 100 39.0 Solvent (DMF) content mg / kg GC / MS 200 or less 141

As shown in Table 4, the sponge-type cured leather produced in the above Examples satisfied all of the tensile strength, elongation, tear strength and flexibility, and the tensile strength, tear strength and flexibility were greatly increased It is confirmed that the impact resistance is improved and the content of the residual organic solvent is reduced, which is effective in reducing the use of environmentally harmful substances.

2 is a SEM photograph showing a cross-section of a sponge-type slim leather according to the present invention.

EXPERIMENTAL EXAMPLE 4-1: Flexibility evaluation of the wet coated skin leather prepared in the above Examples and Comparative Example 1

In order to evaluate the flexibility using the wet-coated skins made by the above-described Examples and Comparative Example 1, the results are shown in the following Table 5 as follows.

Test Items unit result Test Methods Comparative Example 1 Example flexibility mm 2 4 KS M ISO 17235

As shown in Table 5, in Comparative Example 1 in which the additive having a high HLb was not used, the flexibility was remarkably low as compared with the Examples. Thus, it was confirmed that the properties required for use as a smartphone leather case were not satisfied .

Experimental Example 4-2: Evaluation of the solvent content of the wet coated skin prepared in the above Example and Comparative Example 2

In order to evaluate the DMF content of the wet coated skin prepared by the above Examples and Comparative Example 2, the results are shown in the following Table 6 as follows.

Test Items unit result Test Methods Comparative Example 2 Example Solvent (DMF) content mg / kg 3,300 141 GC / MS

As shown in Table 6, in Comparative Example 2 in which vacuum drying using a baking apparatus was not used, it was found that the solvent content was significantly higher than that in the above Examples, indicating that it was not environmentally friendly.

Therefore, the sponge-like slim leather produced according to the above-mentioned embodiment can provide price competitiveness by using the inexpensive slim leather as compared with the expensive silver silk leather, and the environment-friendly sponge-like slim leather can be manufactured by desolvation. Also, it can be seen that a porous polyurethane resin layer is coated on the pretreated leather by pretreatment using a leather fabric wet coating apparatus to impart a soft touch to the leather and improve the physical strength such as impact resistance there was.

Claims (12)

A porous polyurethane resin layer including a urethane resin and wood powder is formed on one side of a six-sided leather,
The polyurethane resin layer is wet coated with a polyurethane resin coating liquid containing 40 to 60% by weight of a urethane resin, 5 to 20% by weight of wood powder, 0.1 to 5% by weight of an additive and 30 to 50% by weight of a solvent,
Wherein the additive is a mixture of organic silicon (Silicone), isoparaffine, and polyether.
delete delete The method according to claim 1,
Wherein the solvent is dimethylformamide (DMF), dimethylsulfoxide (DMSO), or a mixture of the two.
The method according to claim 1,
Wherein the polyurethane resin layer has a thickness of 250 to 400 占 퐉.
The method according to claim 1,
Wherein the polyurethane resin layer has a porous size of 10 to 50 mu m in diameter.
A buffing step of polishing the surface of the skin leather through the tanning process;
A wet coating step of wet-coating a polyurethane resin coating solution on one side of the ground abrasive leather;
A desolvation process in which the wet coated skin is drained using a spray system;
An aging step of moving the desolvated skins to a coagulating bath to solidify the coating liquid;
Drying the coagulated hard leather by vacuum drying at a temperature of 85 to 95 DEG C for 300 to 350 seconds under a vacuum pressure of 0.05 to 0.1 atm;
A drying step of drying the vacuum dried skins; And
A coating step of coating the dried cowhide leather;
≪ / RTI >
The polyurethane resin coating liquid contains 40 to 60% by weight of a urethane resin, 5 to 20% by weight of wood powder, 0.1 to 5% by weight of an additive and 30 to 50% by weight of a solvent,
Wherein the additive is a mixture of organic silicon (Silicone), isoparaffine, and polyether.
8. The method of claim 7,
Wherein the buffing step uses sandpaper of # 240 to # 320.
8. The method of claim 7,
Wherein the polyurethane resin coating solution is wet-coated at a thickness of 250 to 400 탆 in a wet coating process using a leather wet-type wet coating apparatus.
delete delete 6. A smartphone natural leather case using the sponge-like skin of any one of claims 1 and 4 to 6.

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