Standard Selection And Suggestions For Garment Products Of Synthetic Leather And Synthetic Leather

　　 1 Definition and development status of synthetic leather and synthetic leather

　　 Artificial leather The synthetic leather was born in the early days to imitate the dermis. Compared with the real leather, they have the characteristics of average physical properties, abundant raw materials and low price. They have been widely applied in clothing, shoes and other industries. However, at present, there is no uniform definition of artificial leather and synthetic leather in the academic circles. The definitions of different standards are different.

(1) according to the definition of the substrate. According to the term "footwear" (ISO19952:2005), it is known as artificial leather on the basis of warp and weft interwoven textile cloth. The structure of natural leather is used as the standard, and the elastic polymer material is used to impregnate the fiber layer. The elastic polymer material has continuous micro porous structure, and the synthetic material with irregular three-dimensional structure (non-woven fabric) is called synthetic leather.

(2) according to resin definition. Artificial leather is defined in the "discharge standard for pollutants in synthetic leather and artificial leather industry" (GB21902-2008). It is defined as the structure of synthetic polyvinyl chloride resins or similar leather made of synthetic materials, such as fabrics, non-woven fabrics (non-woven fabrics) and other materials, including no base cloth, and looks like natural leather. Synthetic leather: refers to the structure of polyurethane resin formed on the base of fabric, non-woven fabric, leather and other materials by artificial way, or the structure of similar leather, which looks like a material of natural leather.

(3) defined by simulation effect. The Chinese encyclopedia light industrial roll defines the artificial leather and synthetic leather mainly according to the properties of the substrate and the degree of imitation of the leather, that is, the synthetic leather is a plastic product with appearance, touch and leather, which can be partly used instead of it. Usually, it is made of fabric as the base and the coating is synthetic resin. Synthetic leather is the microscopic structure and physical and chemical properties of the natural leather. As the substitute material of the leather, plastic products are usually made of nonwoven fabric as the mesh layer, and the microporous or membrane structure polyurethane as the surface layer. The appearance and performance of the synthetic leather are similar to those of the natural leather.

The above three definitions of synthetic leather and synthetic leather are widely divergent and confusing. "Artificial" and "synthetic" are just different from the processing methods of natural leather. "Artificial leather" and "synthetic leather" can also be called "artificial leather". The development history of artificial leather is reviewed. In 1930s, the nitrocellulose lacquer made from nitrocellulose solution was used to imitate leather. Later, artificial or leather made of woven or knitted material was coated with polyvinyl chloride (PVC) on the surface and made of artificial leather similar to natural leather. In 1950s, polyurethane (PU) gradually replaced PVC PVC as the coating material for artificial leather. Due to the excellent performance of polyurethane, polyurethane artificial leather has become the mainstream of artificial leather rapidly and continues to the present. But the structure is different from the dermis. In 1960s, the imitation leather material made of non-woven fabric was used as the base and the fabric was reinforced in the middle and coated with polyurethane on the surface. It was named polyurethane synthetic leather because its appearance and structure were more like leather. It is the second generation of artificial leather. In 1968, Japan's Polyester microfiber synthetic leather was born. It is the synthetic leather that is most similar to the appearance and properties of natural leather.

Based on the current definition and the development history of artificial leather, it is more reasonable to distinguish artificial leather from synthetic leather based on the difference of base. It is suggested that the definition of artificial leather and synthetic leather can be described in more detail in the new revision standard, and the definition of the type of coating resin combined with the simulation effect of substrate will be clearly defined. For example, polyurethane artificial leather, polyvinyl chloride artificial leather, polyurethane synthetic leather and so on are easier to integrate with the international concept, and are very perfect, which is not only convenient for consumers to understand, but also conducive to the unification of concepts. {page_break}

2 the relationship between artificial leather and coated fabric

In this case, artificial leather refers to the material used in the definition (1) with fabric as the base and synthetic resin as coating agent. Coated fabric is a kind of textile that is coated with adhesive material to form single or multi-layer coating on one side or both sides of the fabric. The characteristics of coated fabrics are as follows:

1) there are various kinds of coating agents for coated fabrics, such as polyacrylate (PA) coatings, polyurethane (PU) coatings, polyvinyl chloride (PVC) coatings, silicone elastomer coatings, synthetic rubber (such as neoprene) coatings, and polytetrafluoroethylene, polyamide, polyester, polyethylene, polypropylene and protein. Among them, polyurethane (PU) coating with strong film sense and polyvinyl chloride (PVC) coating are also common in artificial leather.

2) the base fabric of coated fabric is woven fabric and knitted fabric. It has the same base with artificial leather.

3) the appearance and feel of most coated fabrics are different from those of artificial leather because of the thinner adhesive layer. The purpose is not to imitate natural leather, but to achieve some functions such as windbreak, rain protection, UV protection, or special effects such as paper coating, pearlescent coating and so on. The appearance and feel of synthetic leather are very close to natural leather.

To sum up, the author thinks that in the broad sense, artificial leather (PVC leather and PU leather) based on woven fabrics and knitted fabrics is a special kind of coated fabric.

　 3 selection of testing standards for artificial leather garments

According to the provisions of China's standardization law, the production enterprises have the right to choose product standards, but once they are selected, they must organize production and sales according to the technical requirements of the selected standards, and bear the corresponding civil liability for the potential risks they bring to consumers. Therefore, the right choice of test standard is an important work in quality control and quality inspection in production, and the following points should be noticed in actual selection.

3.1 scope of application of test standards

Artificial leather and synthetic leather garment products should be in conformity with the applicable scope of the selected testing standards. Table 1 is the applicable scope of the relevant testing standards for synthetic leather, synthetic leather fabrics and clothing products.

By comparing the scope of application of the standard and the classification of products, we can see that QB/T1646-2007 Polyurethane synthetic leather The standard is not applicable to garment leather fabrics. Generally speaking, garment enterprises can adopt the other remaining standards for fabric quality control or in fabric purchasing trade. FZ/T73028-2009 "knitted leather garment" is the only standard for garments, and its application scope is only applicable to all kinds of garments made of main fabrics in a variety of knitted synthetic leather (made of knitted fabric and synthetic resin as the main raw material). At present, many artificial leather and synthetic leather products with woven fabrics and non-woven fabrics have not yet issued corresponding industry standards or recommended national standards.

In view of this situation, enterprises in the artificial leather leather garment quality inspection, we must first meet the national mandatory standard GB18401 requirements. If the coating agent is PVC artificial leather, it should also comply with the GB21550-2008 "PVC artificial leather harmful substances limit". In addition, it should meet the requirements of the quality standard of clothing products. For all kinds of knitted artificial leather, FZ/T73028 "knitted artificial leather clothing" can be directly chosen. At present, other artificial leather garments, such as woven synthetic leather garments, do not have corresponding product standards. It is suggested that enterprises should draw up relevant standards and formulate enterprise standards.

3.2 comparison of fabric testing and garment testing standards

The artificial leather fabric with knitted fabric and polyurethane resin as the coating is defined according to the definition (2) which is suitable for the detection of QB/T2958-2008 "polyurethane synthetic leather for clothing". At the same time, the garment is in accordance with the definition (1) or the definition (3), and also meets the testing scope of FZ/T73028-2009 "knitted leather garment". However, there are great differences between the two standards in testing methods and technical indicators of the same items. For example:

1) surface color fastness: QB/T2958-2008 "clothing polyurethane synthetic leather" and FZ/T73028 "knitted leather garment" are the same as the testing methods, but the technical parameters and technical requirements are different. The former (for fabric standard) according to the method standard GB/T3920 "textile color fastness test rubbing color fastness", the dry friction is 10 times, the wet friction is 10 times, the technical requirements are: veneer products: dry: 4 grade, wet: 3 grade, suede products: dry: 3, wet: 2; while the latter (for finished product standard) is clear the number of friction cycles, dry friction is 50 times, wet friction is 10 times, technical requirements dry and wet friction are 3 grade. {page_break}

2) resistance to bursting strength: test method used in "polyurethane synthetic leather for clothing" GB/T1539 "determination of bursting strength of paperboard", referring to GB/T19976 "determination of strength of textile bursting strength" in "knitted leather garment".

3) carcinogenic aromatic amine dye: in QB/T2958-2008 "clothing polyurethane synthetic leather", the method of GB/T19942 "leather and fur chemical test banned azo dye determination" method is used to measure 23 kinds of banned AZO dyes, the technical requirement is <30mg/kg. In the "knitted artificial leather garment" of FZ/T73028, GB/T17592 is used to determine the prohibited azo dyes in textiles. According to GB18401 test, 24 kinds of banned AZO dyes are tested, and the technical requirements are <20mg/kg. There are fewer kinds of AZO dyes in the fabric stage than in the garment stage, and the technical requirements are also low.

4) the fastness of alkali hydrolysis to alkali in the synthetic leather of clothing is 10%, while that in FZ/T73028 "knitted leather garment" is 5%, and the temperature and humidity are different.

5) tearing load: the "polyurethane synthetic leather for clothing" is the same as that of the "knitted leather garment" standard, but the fabric stage is lower than the technical requirements of the garment stage. The former is 12N or 10N, while the latter is 14N.

Therefore, enterprises should pay special attention to product quality inspection. The results of the same test items may vary greatly due to the difference of testing methods, technical parameters or technical requirements according to the test results of semi finished products quality standards and finished products standards. The quality standards for semi finished products, such as "polyurethane synthetic leather for clothing", do not necessarily meet the quality requirements of finished product standards such as FZ/T73028 "knitted leather garment". Therefore, clothing enterprises should not only attach importance to the procurement of fabrics to meet the fabric standards, but also the selection of quality standards and quality inspection.

　 4 recommendations

To sum up, from the broad sense Coated fabric In terms of the scope of the fabric, for the artificial leather garment based on fabric, the enterprise can choose the product standard according to the end use and fabric structure and fabric composition. Such as FZ/T81007 "single, clip clothing", FZ/T81008 "jacket", GB/T2662 "cotton dress" (not suitable for stuffed products for down products), GB/T14272 "down garments" and so on. However, the current version of these standards has only checked the basic performance of clothing. It is not perfect for clothing products produced by artificial leather fabrics coated with polyurethane and polyvinyl chloride chemical resins, such as extractable heavy metals, harmful surface active agents (APEO), low temperature fastness, anti adhesion and alkali resistant liquids. Therefore, in order to reduce risks and build brands better, it is suggested that enterprises should formulate better product enterprise standards. On the one hand, according to the physical and chemical properties of artificial leather, which is different from other textiles, increase the assessment of low temperature fastness, anti adhesion, alkali resistance and other items; on the other hand, enterprises should also refer to the existing industry safety technology standards (such as QB/T4045-2010 "polyurethane household synthetic leather safety technology conditions", QB/T4046-2010 "polyurethane superfine fiber synthetic leather general safety technical conditions"), which is more in line with the requirements of environmental protection and ecology.

In short, artificial leather and synthetic leather are products of various scientific processes. Although their application time is very short, they play an important role in national production and life because they have outstanding features that other materials do not possess. As a new thing, varieties emerge in endlessly, species are hard to define, and the formulation of standards is still far behind the speed of their products being released. This has brought great difficulties to product inspection. It is an important task for enterprises and standardization committees and artificial leather experts to formulate the definition of artificial leather and synthetic leather terms as well as the standards and standards for their identification as soon as possible.