Title of the Invention

Artificial leather and manufacturing method therefor

[Technical Field]

The present invention relates to an artificial leather and a manufacturing method therefor. The artificial leather contains a molecular sieve adsorbent.

[Background art]

Leather is widely used as a surface decorative material in many fields, such as cars and home decorating. Common leathers include real leather, polar artificial leathers such as polyvinyl chloride (referred to hereinbelow as PVC) artificial leather, and non-polar artificial leathers such as thermoplastic polyolefin elastomer (TPO) artificial leather, etc.

In recent years, as living standards in society have risen overall, people have begun to pursue healthy lifestyles to an ever increasing extent. In addition to the indoor air quality at home, consumers are also paying an increasing attention to air quality in cars. Taking the PVC artificial leather widely used in car interiors as an example, since the PVC artificial leather contains volatile organic compounds (referred to hereinbelow as VOC) such as alcohols, acids, and benzene, its odour and VOC emissions have attracted special attention from main engine manufacturers and consumers. Following the publication and implementation of GB 27630 “Guidelines for air quality in vehicles”, the requirements of the main engine manufacturers regarding odour and VOC emissions of car interiors materials became more and more strict. However, existing PVC artificial leather struggles to meet higher requirements of the main engine manufacturers regarding odour levels and VOC emissions.

Thus, it is hoped to propose a novel technical solution to solve the abovementioned technical problems. [Summary of the invention]

The technical problem to be solved by the present invention is to provide an artificial leather and a preparation method therefor, and the artificial leather has a relatively low odour level and VOC emission.

In order to solve the above technical problems, the present invention can be achieved using the following technical solution: an artificial leather comprises a skin layer and a base fabric layer, the base fabric layer contains a molecular sieve adsorbent, and the molecular sieve adsorbent has a pore size of 0.4-1 nm, such as 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, or a pore size within a range of any two of these numerical values, preferably 0.5-0.8 nm, and a silica- aluminaratio greater than 30, preferably greater than 300, more preferably 800, most preferably 800-1 ,000. In the present invention, the molecular sieve adsorbent is a zeolite, having a general formula: (M)2/nO.Al2O3.xSiO2.pH2O, wherein M is a metal ion, n is the valence number of the metal ion, x is the mole number of S iC>2, also referred to as a silica-alumina ratio, and P is the mole number of water.

In the present invention, the skin layer is a polar skin layer or a non-polar skin layer.

In the present invention, the skin layer is a PVC dense layer and a PVC foamed layer, and the artificial leather further comprises a PVC glue layer located between the PVC foamed layer and the base fabric layer. The PVC dense layer comprises a PVC resin, a plasticizer, a stabilizer, a colour powder, and the molecular sieve adsorbent. Based on a total weight of the PVC resin and the plasticizer of 100 parts, the PVC dense layer comprises 40-60 parts of the PVC resin, 40-60 parts of the plasticizer, 1-5 parts of the stabilizer, 1-5 parts of the colour powder, and the molecular sieve adsorbent being 0.5-1 .2 parts, such as 0.5 part, 0.7 part, 0.9 part, 1 .0 part, 1 .2 parts or a range of any two of these numerical values. The PVC foamed layer comprises a PVC resin, a plasticizer, a stabilizer, a foaming agent, a flame retardant, colour powder, and the molecular sieve adsorbent. Based on a total weight of the PVC resin and the plasticizer of 100 parts, the PVC foamed layer comprises 40-60 parts of the PVC resin, 40-60 parts of the plasticizer, 1-5 parts of the stabilizer, 1 -3 parts of the foaming agent, 3-5 parts of the flame retardant, 1-3 parts of the colour powder, and the molecular sieve adsorbent being 0.5-1 .2 parts, such as 0.5 parts, 0.7 parts, 0.9 parts, 1 .0 part, 1 .2 parts or a range of any two of these numerical values. The PVC glue layer comprises a PVC resin, a plasticizer, a stabilizer, and the molecular sieve adsorbent. Based on a total weight of the PVC resin and the plasticizer of 100 parts, the PVC glue layer comprises 40-60 parts of the PVC resin, 40-60 parts of the plasticizer, 1-5 parts of the stabilizer, and the molecular sieve adsorbent being 0.5-1 .2 parts, such as 0.5 parts, 0.7 parts, 0.9 parts, 1 .0 part, 1 .2 parts or a range of any two of these numerical values.

In the present invention, a person skilled in the art can select a conventional PVC resin, such as a PVC emulsification powder with a trade name of P440 sold by Shanghai Chlor-alkali, a PVC emulsification powder with a trade name of KVH sold by Formosa Plastics Corporation, New Jersey, U.S., and a PVC emulsification powder with a trade name of PSM-31 sold by Shenyang Chemical, for the PVC dense layer, the PVC foamed layer and the PVC glue layer according to actual needs.

In the present invention, a person skilled in the art can select a conventional plasticizer, a phthalate plasticizer, such as dialkyl phthalate, a trimellitate plasticizer, such as trialkyl trimel litate, and a combination of two or more plasticizers for the PVC dense layer, the PVC foamed layer, and the PVC glue layer according to actual needs.

In the present invention, a person skilled in the art can select a conventional stabilizer, such as an organic epoxy stabilizer and a calcium-zinc stabilizer, and a combination thereof, for example, a calcium-zinc stabilizer with a trade name of MC 9656 EP sold by Baerlocher Plastic Additives (Jiangsu) Co, Ltd., for the PVC dense layer, the PVC foamed layer, and the PVC glue layer according to actual needs.

In the present invention, a person skilled in the art can select to add or not add a colour powder to the PVC dense layer and the PVC foamed layer according to actual needs. If the colour powder is required to be added, a person skilled in the art can select a conventional colour powder according to actual needs, which can be an inorganic pigment and also an organic pigment, such as iron oxide red, titanium dioxide, iron oxide yellow, chrome yellow, and cadmium red.

In the present invention, other additives, such as an antioxidant, an ultraviolet absorber, etc., can also be added into the PVC dense layer according to needs.

In the present invention, a person skilled in the art can select a conventional foaming agent, such as a physical foaming agent, for example a microsphere foaming agent with a trade name of microsphere Y-150D sold by Wenzhou Jufeng International Trade Co., Ltd., Zhejiang, China, a chemical foaming agent, for example, azodicarbonamide, or a combination of multiple foaming agents, for the PVC foamed layer according to actual needs.

In the present invention, a person skilled in the art can select to add or not add a flame retardant to the PVC foamed layer according to actual needs. If the flame retardant is required to be added, a person skilled in the art can select a conventional flame retardant according to actual needs, such as aluminum hydroxide, magnesium hydroxide, antimonous oxide, a halogen-based flame retardant, a phosphorus-based flame retardant, and a nitrogen-based flame retardant.

In the present invention, it is well known to a person skilled in the art that a slurry viscosity of a raw material of the PVC dense layer during material mixing generally needs to be controlled in a range of 3,000 to 30,000 mpa.s, and a slurry viscosity of a raw material of the PVC glue layer during material mixing generally needs to be controlled in a range of 4,000 to 15,000 mpa.s. It is well known to a person skilled in the art to control the slurry viscosity of the PVC dense layer and the PVC glue layer mainly by selecting a PVC resin of a different viscosity and adjusting the ratio of the PVC resin to the plasticizer. In the present invention, it is also well-known to a person skilled in the art, the PVC resin in the PVC dense layer, the PVC resin in the PVC foamed layer, and the PVC resin in the PVC glue layer may be the same or different. The plasticizer in the PVC dense layer, the plasticizer in the PVC foamed layer, and the plasticizer in the PVC glue layer may be the same or different. The stabilizer in the PVC dense layer, the stabilizer in PVC foamed layer, and the stabilizer in PVC glue layer may be the same or different. The colour powder in the PVC dense layer and the colour powder in the PVC foamed layer may be the same or different.

In the present invention, the molecular sieve adsorbent is arranged on a side, facing the skin layer, of the base fabric layer, or both sides of the base fabric layer or both sides and the inside of the base fabric layer.

In the present invention, based on a total weight of the base fabric layer, the base fabric layer contains 0.3%-2% of the molecular sieve adsorbent. If the molecular sieve adsorbent is too little, the adsorption effect is not good, but the base fabric cannot adsorb too much molecular sieve adsorbent limited by the adsorption capacity of the base fabric itself.

In the present invention, the base fabric layer can be made of a polyester weft- knitted fabric, of course, can also be chinion, warp-knitted or non-woven fabric, and also woven by a machine.

In the present invention, the PVC artificial leather further comprises a paint layer on a surface of the skin layer. A person skilled in the art can select a conventional paint layer according to needs, preferably a water-based polyurethane paint.

In order to solve the above technical problems, the present invention can also be achieved using the following technical solution: a manufacturing method for the artificial leather, wherein the base fabric layer of the artificial leather is manufactured by performing a water washing process on a base fabric, by a production process comprising weaving, water washing, and heat setting the base fabric layer, in the water washing, a molecular sieve adsorbent is added into a water washing tank, and the molecular sieve adsorbent is attached to the base fabric during the water washing process of the base fabric, and in the heat setting, water on the base fabric is dried and the molecular sieve adsorbent remains on the base fabric.

Compared with the prior art, the present invention has the following beneficial effects: by a large number of experiments and researches, the applicant unexpectedly finds that the addition of a molecular sieve adsorbent with a specific pore size (0.4-1 nm) and a specific silica-alumina ratio (greater than 30) into a base fabric layer can effectively reduce the odour levels and VOC emissions of an artificial leather prepared therefrom, meets the higher requirements for the odour levels and VOC emissions by people, effectively improves the pleasure and ensures health of a user, and achieves an unexpected technical result.

[Detailed Description of Embodiments]

The present invention is further illustrated by the following examples and comparative examples.

Example 1

The present example involves the preparation of a PVC artificial leather, the preparation method of the PVC artificial leather used in this example is a convention method in the art, and a person skilled in the art would have clearly known how to select specific apparatuses, process steps and conditions; therefore, the following description of the preparation process only involves the critical steps and conditions for one of the preparation methods.

Step I, material mixing

In accordance with formulations of the dense layer given in Tables 1 -1 and 2, components of the formulations of the dense layer given in Tables 1-1 and 2 are put into a material mixing tank, and then stirred mechanically under vacuum until being uniformly mixed. Thus a PVC slurry of a skin layer is obtained.

In accordance with formulations of the foamed layer given in Tables 1 -1 and 2, components of the formulations of the foamed layer given in Tables 1 -1 and 2 are put into a mixing tank, and then stirred mechanically under vacuum until being uniformly mixed. Thus a PVC slurry of the foamed layer is obtained.

In accordance with formulations of the glue layer given in Tables 1 -1 and 2, components of the formulations of the glue layer given in Tables 1 -1 and 2 are put into a mixing tank, and then stirred mechanically under vacuum until being uniformly mixed. Thus a PVC slurry of the glue layer is obtained.

Step II, manufacturing of base fabric

A polyester weft-knitted fabric is manufactured by weaving, water washing, and heat setting.

Step III, coating and base fabric attaching

Firstly, the PVC slurry of a skin layer is coated to release paper by using an indirect coating method and then fed into a first-stage oven for plasticizing and setting. Then the plasticized and set dense layer is coated with the PVC slurry of a foamed layer and continuously fed into a second-stage oven for plasticizing and setting. Next the PVC slurry of a glue layer is roller-coated to the plasticized and set foamed layer, and then a polyester weft-knitted fabric is combined thereto, and fed into a third-stage oven for final setting, so as to obtain a PVC artificial leather coated material. After taking out of the oven, the PVC artificial leather coating material is separated from the release paper, and the two are rolled up individually. The rolled-up PVC artificial leather coating material is sent to a printing stage.

Step IV, printing

In a printing stage, after the rolled-up PVC artificial leather coating material is unrolled, a water-based polyurethane paint is printed onto the dense layer of the PVC artificial leather coating material. After the water-based polyurethane paint is printed by a printing machine, the same is sent to the oven for drying, then cooled and rolled up, so as to obtain a printed semi-finished product of the rolled-up PVC artificial leather. The printed semi-finished product of the PVC artificial leather is sent to an embossing stage. Step V, embossing

In the embossing stage, the above-mentioned rolled-up printed semi-finished product of the rolled-up PVC artificial leather is unrolled. The surface of the printed semi-finished product of the PVC artificial leather is softened by means of heating, and by using an embossing roller, the pattern on the surface of the embossing roller is imparted onto the PVC artificial leather side by pressure. After cooling same, a PVC artificial leather with patterns on the surface is obtained.

Examples 2-8

Examples 2-8 also involve a preparation of a PVC artificial leather. The preparation process for the PVC artificial leather, raw materials of a paint layer, and selection of a base fabric layer are all exactly the same as in example 1 . Differences are shown in Tables 1-1 , 1 -2, and 2.

Examples 9-12

Examples 9-12 also involve a preparation of a PVC artificial leather. The preparation process for the PVC artificial leather and raw materials of a paint layer are both exactly the same as in example 1 . Differences are shown in Tables 1-1 , 1- 3, and 2. With regard to manufacturing of a base fabric, in the water washing, a molecular sieve adsorbent is added into a water washing tank, and the molecular sieve adsorbent is attached to the base fabric during the water washing process of the base fabric, and in heat setting, water on the base fabric is dried and the molecular sieve adsorbent remains on the base fabric.

Comparative examples 1-3

Comparative examples 1-3 involve a preparation of a PVC artificial leather as well. The preparation process for the PVC artificial leather, raw materials of a paint layer, and selection of a base fabric layer are all exactly the same as in example 1 . Differences are shown in Tables 1-1 , 1-4, and 2.

Table 1-1

Table 1-2

Table 1-3

Table 1-4

Table 2

Testing of odour levels and VOCs of PVC artificial leathers:

The PVC artificial leathers prepared in examples 1-12 and comparative examples 1 -3 are tested for odour levels in accordance with the Volkswagen’s odour testing method PV 3900 C3. The test results are shown in Table 3.

The odour characteristics of materials are classified as follows according to the standard specifications: level 1-no odour; level 2-there is odour, but no disturbing odour; level 3-there is obvious odour, but no disturbing odour; level 4-there is disturbing odour; level 5-there is strong disturbing odour; and level 6-there is unbearable odour.

The PVC artificial leathers prepared in examples 1-12 and comparative examples 1-3 are tested for total volatile organic compounds (TVOCs) in accordance with the Volkswagen’s total volatile organic compound (TVOC) testing method, a 2,000L bag method. The test results are shown in Table 3.

Fatigue test of PVC artificial leathers:

The PVC artificial leathers prepared in examples 1-12 and comparative examples 1-3 are subjected to a fatigue test in accordance with the test method of ISO 5402. The test results are shown in Table 3.

Table 3

It can be seen from the examples, comparative examples, and test results above that the pore size and the silica-alumina ratio of the molecular sieve adsorbent jointly affect the odour levels and VOC emissions of the PVC artificial leathers. When the molecular sieve adsorbent with a pore size of 0.4-1 nm and a silica- alumina ratio greater than 30 is added into the PVC dense layer, the PVC foamed layer, the PVC glue layer, and the base fabric layer, the prepared PVC artificial leather has a relatively low odour level and VOC emission. Within the above range, when the silica-alumina ratio of the molecular sieve adsorbent is determined, the molecular sieve adsorbent with a greater pore size has a better adsorption effect. Within the above range, when the pore size of the molecular sieve adsorbent is determined, the molecular sieve adsorbent with a greater silica-alumina ratio has a better adsorption effect. But when the silica-alumina ratio of the molecular sieve adsorbent is greater than 800, a change of the silica- alumina ratio has no significant effect on the adsorption effect of the molecular sieve adsorbent. The molecular sieve adsorbent with a larger silica-alumina ratio has a more complicated processing process and a higher cost. When the base fabric layer contains the molecular sieve adsorbent, the fatigue resistance of the PVC artificial leather can be improved by reducing the content of the molecular sieve adsorbent in the PVC dense layer, the PVC foamed layer, and the PVC glue layer. Besides, there is no too big effect on the odour levels and the VOC emissions of the PVC artificial leather.

It can be understood that the above examples of the present invention may be combined with each other to obtain more examples under the condition of no conflict. The various specific technical features described in the above specific embodiments may be combined in any suitable manner under the condition that they do not contradict.

The above examples are only preferred examples of the present invention rather than all examples. It can be understood that those of ordinary skill in the art can make many reasonable changes to the technical solutions of the present invention without departing from the essential spirit and scope of the present invention, and these reasonable changes are all within the protection scope of the present invention.