SUEDE TYPE ARTIFICIAL LEATHER WITH ANTIFOULING PROPERTY AND PREPARATION METHOD THEREFOR

Abstract

A suede type artificial leather having an antifouling property is provided. A polymeric elastomer is impregnated in a nonwoven fabric formed by three-dimensionally interlacing ultrafine fibers and raising is formed, wherein the polymeric elastomer is a fluorine-containing modified polyurethane, and the fluorine-containing modified polyurethane is obtained by a polymerization of a urethane prepolymer having isocyanate groups at terminals, obtained by reacting a diol and a diisocyanate, and a fluorinated carbon compound having hydroxy functional groups at both terminals. The fluorine-containing modified polyurethane has a weight average molecular weight of 500,000 to 800,000. The suede type artificial leather is prepared by using the fluorine-containing polyurethane elastomer.

Claims

1. A suede type artificial leather having antifouling property in which a polymeric elastomer is impregnated in a nonwoven fabric formed by three-dimensionally interlacing ultrafine fibers and raising is formed, wherein the polymeric elastomer is a fluorine-containing modified polyurethane, and the fluorine-containing modified polyurethane is a product obtained by a polymerization reaction between a urethane prepolymer having isocyanate groups at terminals, obtained by reacting a diol and a diisocyanate, and a fluorinated carbon compound having hydroxy functional groups at both terminals, and has a weight average molecular weight (Mw) of 500,000 to 800,000.

2. The suede type artificial leather having antifouling property according to claim 1, wherein the urethane prepolymer has a weight average molecular weight (Mw) of 400,000 to 700,000.

3. The suede type artificial leather having antifouling property according to claim 1, wherein the fluorinated carbon compound having hydroxy functional groups at both terminals, has 8 to 14 fluorine groups bonded to one side chain and fluorine content of 50 to 70 mol % in one functional group and is an ether diol having hydroxy functional groups at both terminals.

4. A method of preparing a suede type artificial leather having antifouling property in which a polymeric elastomer is impregnated in a nonwoven fabric formed by three-dimensionally interlacing ultrafine fibers and raising is formed, wherein the polymeric elastomer is a fluorine-containing modified polyurethane, and the fluorine-containing modified polyurethane is prepared by a method comprising: preparing a urethane prepolymer having a weight average molecular weight (Mw) of 400,000 to 700,000 by reacting a diol and a diisocyanate; and preparing a polymerization product having a weight average molecular weight (Mw) of 500,000 to 800,000 by reacting the prepolymer and a fluorinated carbon compound having hydroxy functional groups at both terminals.

5. The method of preparing a suede type artificial leather according to claim 4, wherein the diol and the diisocyanate is reacted at a molar ratio of 1:1.2 to 1:1.4 to prepare the urethane prepolymer.

6. The method of preparing a suede type artificial leather according to claim 4, wherein the fluorinated carbon compound having hydroxy functional groups at both terminals, has 8 to 14 fluorine groups bonded to one side chain and fluorine content of 50 to 70 mol % in one functional group and is an ether diol having hydroxy functional groups at both terminals.

Description

BEST MODE

[0023] The present invention relates to a suede type artificial leather having antifouling property in which a polymeric elastomer is impregnated in a nonwoven fabric formed by three-dimensionally interlacing ultrafine fibers and raising is formed, wherein the polymeric elastomer is a fluorine-containing modified polyurethane.

[0024] The fluorine-containing modified polyurethane is a product obtained by a polymerization reaction between a urethane prepolymer having isocyanate groups at terminals and a weight average molecular weight (Mw) of 400,000 to 700,000, obtained by reacting a diol and a diisocyanate, and a fluorinated carbon compound having hydroxy functional groups at both terminals, and has a weight average molecular weight (Mw) of 500,000 to 800,000.

[0025] The diol may be used alone or in combination with diols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol or polytetramethylene glycol.

[0026] The diisocyanate may be 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- to 1,4-diisocyanate, 1-isocyanate-3-isocyanatemethyl-3,5,5-trimethylcyclohexane(isophorone diisocyanate), bis-(4-isocyanatecyclohexyl) methane(hydrogenated MDI), 2- to 4-isocyanatecyclohexyl-2-isocyanatecyclohexylmethane, 1,3- to 1,4-tetramethylxylene diisocyanate, 2,4- to 2,6-diisocyanate toluene, 2,2-2,4- to 4,4′-diphenylmethane diisocyanate , 1,5-naphthalene diisocyanate, xylene diisocyanate or diphenyl-4,4-diisocyanate, and the like, but are not limited thereto.

[0027] In the present invention, when the diol is reacted with the diisocyanate, the proportion to be reacted needs an excess amount of all NCO groups rather than all OH groups. By adjusting the ratio of the diol and the diisocyanate to react as such, the resulting urethane prepolymer may have an isocyanate group terminal in side chains thereof.

[0028] At this time, the molar ratio of the diol and the diisocyanate is preferably 1:1.2 to 1:1.4 because the fluorine-containing modified polyurethane having the weight average molecular weight range of the present invention can be produced.

[0029] When the molar ratio is less than 1:1.2, a side reaction occurs due to moisture or active hydrogen, etc. in the air, or the isocyanate reacts with each other to manifest a property of isocyanate for forming a trimer and to decrease the polymerization efficiency due to the increase of inactive NCO. When the molar ratio is more than 1:1.4, the excess of NCO groups causes an insufficient OH group so that it is difficult to raise the degree of polymerization.

[0030] In order to ensure the mechanical properties required in case that the fluorine-containing modified polyurethane of the present invention is applied to artificial leather, it is necessary to increase the polymerization molecular weight to an appropriate level easily and to do so, a urethane prepolymer can be prepared first.

[0031] If the weight average molecular weight (Mw) of the urethane prepolymer is less than 400,000, the molecular weight of the fluorine-containing modified polyurethane is lowered, and the mechanical properties such as tear strength, etc. and the chemical properties such as thermal stability and hydrolysis resistance, etc. are lowered. If it exceeds 700,000, the gelation phenomenon may occur in the production of the fluorine-containing modified polyurethane, and the viscosity of the fluorine-containing modified polyurethane may be high to reduce the workability in blending of an elastomer impregnation solution, and the resulting fluorine-containing modified polyurethane may be hardened, which may deteriorate the sensual quality in artificial leather.

[0032] The fluorinated carbon compound having hydroxy functional groups at both terminals is represented by the following Chemical Formula 1, has 8 to 14 fluorine groups bonded to one side chain and fluorine content of 50 to 70 mol % in one functional group and is an ether diol having hydroxy functional groups at both terminals.

HO—CH.sub.2—CF.sub.2—O—(CF.sub.2CF.sub.2O) m-(CF.sub.2O) n-CF.sub.2—CH.sub.2—OH   [Chemical Formula 1]

[0033] The fluorine-containing modified polyurethane obtained by reacting the ether diol of the Chemical Formula 1 with the urethane prepolymer can provide water-repellent and oil-repellent functions because the fluorine which is present as the diatomic molecule in the element state, in the side chain of the urethane polymer is bonded to prevent that the modified polyurethane is bonded to other atoms or molecules. Thus, by the fluorine-containing modified polyurethane of the present invention, the artificial leather can be suppressed deposition of an external contaminant and easily removed contaminants on the coated surface.

[0034] A commercialized product of a fluorinated carbon compound having hydroxy functional groups at both terminals is Solvay's FLUOROLINK.

[0035] The polymerization of the fluorine-containing modified polyurethane of the present invention can be carried out through the addition-polymerization by adding dropwise the fluorinated carbon compound having hydroxy functional groups at both terminals to the urethane prepolymer until the desirable molecular weight is reached. At this time, the addition amount of the fluorinated carbon compound corresponds to the moles of excess isocyanate in preparing the urethane prepolymer.

[0036] When a fluorinated carbon compound having hydroxy functional groups at both terminals is added at a time, the fluorinated carbon compound is partially bound to the urethane prepolymer, so that the dispersion of the fluorine groups in the fluorine-containing modified polyurethane becomes insufficient and as a result it is difficult to develop the uniform antifouling performance. Therefore, it is preferable to slowly add dropwise.

[0037] The fluorine-containing modified polyurethane of the present invention is polymerized by the above-mentioned method and is characterized by having a weight average molecular weight (Mw) of 500,000 to 800,000. If the weight average molecular weight (Mw) is less than 500,000, the mechanical strength such as tear strength, etc. and chemical properties such as thermal stability, hydrolysis resistance, and the like in artificial leather may be reduced. When the weight average molecular weight (Mw) is more than 800,000, the viscosity of the fluorine-containing modified polyurethane may be high to reduce the workability in blending of an elastomer impregnation solution, and the resulting fluorine-containing modified polyurethane may be hardened, which may deteriorate the sensual quality in artificial leather.

[0038] It is preferable that the fluorine-containing modified polyurethane of the present invention has a fluorine content of 5 to 20mol %. When the content is less than 5 mol %, the antifouling performance is insufficient, and when the content is more than 20 mol %, the water repellency is too strong so that the fluorine-containing modified polyurethane cannot undergo the substitution solidification in the manufacturing process of the artificial leather.

[0039] An example of the synthesis reaction of the fluorine-containing modified polyurethane described above can be represented by the following reaction:

##STR00001##

[0040] Here, R and R′ are each independently an alkyl group.

[0041] Generally, artificial leather can be prepared by immersing a nonwoven fabric formed by three-dimensionally interlacing ultrafine fibers in an impregnating liquid comprising a polymeric elastomer such as polyurethane, impregnating the polymeric elastomer to solidify the elastomer in the nonwoven fabric, raising by grinding and dyeing.

[0042] In the present invention, the fluorine-containing modified polyurethane of the present invention can be used as a polymeric elastomer of the impregnating liquid. The fluorine-containing modified polyurethane may be used as an impregnating liquid by diluting it in dimethyl formamide of 100 to 200 wt % in respect of the weight of the fluorine-containing modified polyurethane.

[0043] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

PREPARATION EXAMPLE 1

[0044] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.2 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 40% by weight to prepare an NCO-terminated polyurethane prepolymer having a weight average molecular weight (Mw) of 700,000.

[0045] The prepared prepolymer was subjected to addition polymerization with 0.2 mol of a fluorinated carbon compound having hydroxy functional groups at both terminals in a side chain (trade name: FLUOROLINK D10-H, manufactured by Solvay, Mw: 1,400) and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 30% by weight to prepare a fluorine-containing modified polyurethane having a weight average molecular weight (Mw) of 800,000.

PREPARATION EXAMPLE 2

[0046] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.3 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 40% by weight to prepare an NCO-terminated polyurethane prepolymer having a weight average molecular weight (Mw) of 600,000.

[0047] The prepared prepolymer was subjected to addition polymerization with 0.3 mol of a fluorinated carbon compound having hydroxy functional groups at both terminals in a side chain (trade name: FLUOROLINK D10-H, manufactured by Solvay, Mw: 1,400) and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 30% by weight to prepare a fluorine-containing modified polyurethane having a weight average molecular weight (Mw) of 700,000.

PREPARATION EXAMPLE 3

[0048] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.4 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 40% by weight to prepare an NCO-terminated polyurethane prepolymer having a weight average molecular weight (Mw) of 400,000.

[0049] The prepared prepolymer was subjected to addition polymerization with 0.4 mol of a fluorinated carbon compound having hydroxy functional groups at both terminals in a side chain and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 30% by weight to prepare a fluorine-containing modified polyurethane having a weight average molecular weight (Mw) of 500,000.

PREPARATION EXAMPLE 4

[0050] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.0 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 70% by weight to prepare a reaction-terminated polyurethane having a weight average molecular weight (Mw) of 700,000.

PREPARATION EXAMPLE 5

[0051] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.7 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 40% by weight to prepare an NCO-terminated polyurethane prepolymer having a weight average molecular weight (Mw) of 350,000.

[0052] The prepared prepolymer was subjected to addition polymerization with 0.7 mol of a fluorinated carbon compound having hydroxy functional groups at both terminals in a side chain and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 30% by weight to prepare a fluorine-containing modified polyurethane having a weight average molecular weight (Mw) of 450,000.

PREPARATION EXAMPLE 6

[0053] Polytetramethylene glycol (Mw: 1,500-2,500) of 0.45 mol, ethylene glycol of 0.47 mol and 1,4-butanediol of 0.08 mol were subjected to addition polymerization with 1.0 mol of 4,4′-diphenylmethane diisocyanate, and the produced polymerization product was diluted and dissolved in dimethylformamide so as to be a total solid content of 70% by weight to prepare a reaction-terminated polyurethane having a weight average molecular weight (Mw) of 700,000.

EXAMPLE 1

[0054] The fluorine-containing modified polyurethane of the Preparation Example 1 was diluted with 150% by weight of dimethylformamide in respect of the weight of the polyurethane to prepare an impregnating liquid.

[0055] The nonwoven fabric in which the polyester fibers (0.3 denier, fiber length: 51 mm) was entangled was immersed in the impregnation solution, taken out and carried out coagulating process in an aqueous solution diluted with 20% by weight of dimethylformamide to form the fluorine-containing modified polyurethane elastomer impregnated nonwoven fabric in which a fine porous layer was formed in the fiber structure.

[0056] Thereafter, a suede type artificial leather was produced by raising finishing on the surface of the elastomer impregnated nonwoven fabric.

EXAMPLE 2

[0057] A suede type artificial leather was produced in the same manner as in Example 1, except that the fluorine-containing modified polyurethane of Preparation Example 2 was used to prepare an impregnation solution.

EXAMPLE 3

[0058] A suede type artificial leather was produced in the same manner as in Example 1, except that the fluorine-containing modified polyurethane of Preparation Example 3 was used to prepare an impregnation solution.

COMPARATIVE EXAMPLE 1

[0059] A suede type artificial leather was produced in the same manner as in Example 1, except that the fluorine-containing modified polyurethane of Preparation Example 4 was used to prepare an impregnation solution.

COMPARATIVE EXAMPLE 2

[0060] A suede type artificial leather was produced in the same manner as in Example 1, except that the fluorine-containing modified polyurethane of Preparation Example 5 was used to prepare an impregnation solution.

COMPARATIVE EXAMPLE 3

[0061] A suede type artificial leather was produced in the same manner as in Example 1, except that the reaction-terminated polyurethane of Preparation Example 6 is diluted with a mixture of 150% by weight of dimethylformamide and 0.5% of a fluorine-based surfactant (trade name FC-4430, 3M) with respect of the weight of the polyurethane, to prepare an impregnation solution.

[0062] The weight average molecular weights (Mw) of the polymer prepared in the above Examples and Comparative Examples were measured using gel permeation chromatography (GPC) (RI-8000, manufactured by Tosoh Corporation) passing through the column connected TSKgel super HM-L, TSKgel super HM-M and TSKgel super HM-N (tosoh) in series with tetrahydrofuran (flow rate: 1 mL/min) as a mobile phase and the column oven at temperature of 40° C.

[0063] The raw material composition ratio for the polymerization in the above Preparation Examples and the weight average molecular weight of the polymerization product are shown in the following Table 1.

TABLE-US-00001 TABLE 1 Preparation Preparation Preparation Preparation Preparation Preparation Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 diol   1 mol   1 mol   1 mol 1 mol   1 mol 1 mol Diisocyanate 1.2 mol 1.3 mol 1.4 mol 1 mol 1.7 mol 1 mol prepolymer 700,000 600,000 400,000 700,000 350,000 700,000 FLUOROLINK 0.2 mol 0.3 mol 0.4 mol — 0.7 mol — D10-H Fluorine- 800,000 700,000 500,000 — 450,000 — containing modified polyurethane surfactant — — — — — 0.5% (FC-4430) The value of the surfactant is that in elastomer impregnation solution.

[0064] The properties of the artificial leather prepared in the above Examples and Comparative Examples were evaluated according to the following antifouling property evaluation method, and the results are shown in Table 2 below.

[0065] Evaluation Method of Antifouling Property

[0066] An artificial leather sample was cut into a size of 5×15 cm and placed in a rubbing fastness tester (model name DL-2007) and a test fabric (product name: IEC carbon black/mineral oil, manufactured by EMPA) was placed on the surface of the fouled sample and rubbed by 10 times reciprocating motion, and the fouled sample was visually compared to give a fouling degree.

[0067] (Standard of fouling grade,

[0068] 5: no visible fouling, 4: slightly visible but almost inconspicuous fouling, 3: slightly fouled and visible, 2: slightly severe fouling, 1: significant fouling)

[0069] Water Repellency Evaluation Method

[0070] The artificial leather sample was fixed (diameter 10 cm) as shown in FIG. 2 and then tilted at an angle of 45°. Then, 100 ml of water was injected into the spray-type funnel located at the upper part, and the degree of distribution of the water droplets on the surface of the sample after the completion of the spraying was observed to give a rating according to FIG. 3.

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Example 3 Fouling 3.5 3.5 3.5 2.0 2.5 3.5 grade Water 3.5 4.0 4.5 2.5 3.0 2.5 repellency rating

[0071] As shown in the above Table 2, it can be confirmed that, the artificial leather of the Example according to the present invention, in which the fluorine-containing modified polyurethane is impregnated as an elastomer has the same antifouling performance as the artificial leather (Comparative Example 3) in which the fluorine-containing surfactant was separately added, and exhibits improved water repellency at the same time.

[0072] The artificial leather according to the present invention is an artificial leather in which a fluorine-containing modified polyurethane having an antifouling property is impregnated. The fluorine-containing surfactant does not need separately for the antifouling property during the production of artificial leather so that productivity increase is possible. The artificial leather according to the present invention exhibits an excellent antifouling performance that suppresses the surface change with the passage of time of the artificial leather caused by using a fluorine-containing surfactant, thereby improving the appearance quality of the artificial leather.

[0073] Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this description is only for a preferred embodiment and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.