Comparison of artificial leather and application of PU synthetic leather in automobile interiors

Comparison of artificial leather and application of PU synthetic leather in automobile interiors

1 Introduction

Due to population growth, the environmental protection and social needs. growing demand, genuine leather can no longer meet people\'s daily life needs. In particular, the processing of genuine leather has caused great environmental pollution. Limited natural resources are becoming increasingly scarce, which is why synthetic leather has emerged as the times demand it. As a substitute for natural leather, artificial leather can not only overcome the shortcomings of real leather such as low utilization rate, low wear resistance, low tear resistance, uneven texture and difficulty cutting, but also solve the problem of the growing shortage of genuine leather. leather resources and its environmental impactental during processing. causing major pollution problems [1]. Artificial leather is widely used in the field of automobile interiors because of its soft feel, clear and natural texture, good color fastness of the finished product, easy cleaning, good flame retardancy and heat dissipation, and easy mechanical drilling. As Chinese automobile production continues to increase, the amount of leather used in automobiles has also increased significantly.

2 Development process of artificial leather

The development of artificial leather basically went through three stages: in the 1930s , artificial leather covered with PVC polymer material has achieved industrial practical application as a substitute for natural leather. This is the first generation of artificial leather products. In the 1960s, with the polyurethane industry and nonwoven technology,artificial leather The application of microfiber PU synthetic leather has given rise to the second generation of synthetic leather; the emergence of microfiber PU synthetic leather is the third generation of artificial leather.

3 Comparison of raw materialsAll the properties of artificial leather

Artificial leather can be divided into PVC artificial leather according to different coating layer materials. Leather and PU artificial leather, PU artificial leather includes general PU leather and microfiber leather.

3. 1 PVC artificial leather

PVC artificial leather appeared in the 1930s, realized the industrialization of replacing natural leather. Practical application target, it is the first generation of artificial leather products. This leather has many disadvantages.

a. PVC resin coating has poor adhesion to the base fabric, stiff feel, poor softness andpoor breathability.

b. Poor environmental protection, which is the biggest disadvantage of PVC artificial leather. During the PVC production process, highly toxic dioxins are produced and released; In addition, the additives of PVC products (such as plasticizers and flame retardants, etc.) also contain some aldehydes and benzene which are more harmful to the human body. quasi-volatile sexual compounds. Therefore, the use of PVC artificial leather in car interiors will pollute the indoor environment and affect the sensory quality of the indoor environment.

c. The problem of disposal of PVC waste is very difficult. Whether burned or buried, it will produce and release dioxins and chlorine compounds that will pollute land and water. Recycling is very difficult.

Therefore, although PVC artificial leather still occupiesBears a dominant position in artificial leather products used in automobile interiors, its overall performance has not met the market development requirements. Today, as humans pay more and more attention to environmental protection and health, PVC artificial leather will gradually be phased out. 3. 2 PU artificial leather

3. 2. 1 General PU Leather

In the 1960s, with the development of polyurethane ThThe application of non-woven materials and technologies in artificial leather gave rise to the second generation of artificial leather: general PU leather. Polyurethane is an emerging organic polymer material with the following advantages.

a. High strength, thin and elastic, soft, smooth, good breathability and waterproof.

b. It still has good tensile and flexural strength at low temperatures, as well as good resistance.ance to photoaging and hydrolysis.

c. Flexible, hard-wearing, close to natural leather in appearance and performance, easy to wash, decontaminate and sew.

d. The surface is smooth and compact and can be treated and stained in a variety of varieties.

It can be seen that as an automotive interior material, high-performance polyurethane can provide excellent wear resistance and hydrolysis resistance, and also meet the requirements low volatility.

3. 2. 2 Superfine fiber leather

Superfine fiber leather, called microfiber leather, is one of the artificial leathers. A newly developed high quality leather. Due to its advantages of wear resistance, cold resistance, breathability, aging resistance, soft texture and beautiful appearance, it has become an ideal material to replace natural leather [2].

4. Comparisonof structural simulation

With the application of non-woven technology in the processing of artificial leather, PU synthetic leather has a network structure similar to that of natural leather. Through wet processing, a dense layer similar to the grain structure of genuine leather is formed on the leather surface, so that the appearance, internal structure and physical properties of PU synthetic leather are closer to those of leather. natural. Natural leather.

Microfiber PUThe emergence of synthetic leather represents a major breakthrough in the development of artificial leather. It is like step further based on PU synthetic leather. Through accumulated research on the microstructure of the dermis, bundled ultrafine fibers with a leather-like collagen structure have been successfully developed. This product adopts PU impregnation and composite surface layer processing technology with superior structure.open-pore structure, which brings into play the immense surface area and high water absorption of ultrafine fibers. It has the hygroscopic properties inherent in natural leather, so the internal microstructure and appearance, texture, physical properties and wearing comfort are comparable to those of high-quality natural leather.

PVC artificial leather only uses knitted or woven fabric as a base. Its structural performance cannot be compared with PU synthetic leather, let alone microfiber leather. It\'s only in appearance. It is close to natural leather, and its overall performance does not adapt to the changing requirements of market development.

5. Application and development of automotive PU interior leather

5. 1 Dry PU interior leather

The processing of dry P U synthetic leather is to apply a layer of P U resin to the surface of the fabric. Fabrics currently usedwovens are mainly dense elastic knits, which are segmented during processing. Heat and dry to volatilize the solvent into the slurry, and the PU resin is cured and tightly combined with the fabric layer to form a dense layer. In order to improve the bond strength between the resin and the base fabric, a two-component bonding resin can be used; at the same time, pre-foaming or surface activity can be added during processing. A microporous polymer layer is formed on the surface of the fabric by methods such as chemical agents, so that it has air-permeable micropores similar to the wet process. Although dry-processed PU synthetic leather is poor in fullness and resilience, it is better in wear resistance and scratch resistance. Strength, hydrolysis resistance and weather resistance. At the same time, it has a low VOC content during productionand processing and is virtually odorless. And the price is low, the hand is soft, light and fine, and the surface has a strong leather feel, so it has been widely used in car seat armrests and cushions.

5. 2 Wet PU automotive interior leather

The production process of wet PU synthetic leather is mainly to impregnate the polyurethane resin or coat it on the base material, and then coat it. wash with water to solidify the resin. attached to the base fabric to form a semi-finished product, which is combined with release paper plating, grinding, embossing and other post-processing processes to produce various types and styles. product, is an excellent substitute for natural leather. Its general characteristics are as follows: synthetic leather has good low temperature resistance, good air and moisture permeability, and has a warm hand feeling.arnue.Good resilience and overall strong leather feel. However, the hydrolysis resistance and scratch resistance are slightly worse, and the cost is higher than that of dry-processed PU leather.

At present, domestic solid PU synthetic leather manufacturers are actively developing and applying new functional PU resin slurries. This resin uses polycarbonate with good durability. , polycaprolactone polyol and isophorone diisocyanate, which resists yellowing, are polymerized as the main raw materials [4]. PU synthetic leather made from this resin has better mechanical properties and resistance to hydrolysis, heat, oxidation and wear. Therefore, it has been widely used in automobile armrests, seats, door guards, etc. It has the characteristics of solid leather feel, soft leather feel.soft to the touch, good elasticity, luxurious appearance and natural luster. This kind of PU synthetic leather has gradually been recognized and welcomed by automobile manufacturers, and its development prospects are very broad[5]

5. 3 Eco-friendly PU automotive interior leather

Since DMF is commonly used as a solvent in the production process of PU synthetic leather at home and abroad , the wet process uses water to extract the solvent into the wet slurry to solidify the polyurethane resin on the fabric. Among them, the mass fraction of volatile solvents reaches 30-40%, so it is not conducive to the health of operators and has an impact on the environment. Eco-friendly PU synthetic leather is mainly produced from water-based resins, high-solids resins and TPU. Since resins based onwater and TPU do not contain solvents, and high solids resins contain only a small amount of solvents, the production process has little impact on the environment. The synthetic leather produced has less residual solvents, low VOC content and low energy consumption. However, resin-produced PU synthetic leather is slightly less durable, scratch-resistant and wear-resistant than solvent-based PU synthetic leather, and is more expensive. The processing of synthetic leather produced by TPU is more difficult, so it is environmentally friendly. The development direction of automotive PU synthetic leather is mainly to use high solid resin for production. Domestic and foreign PU synthetic leather enterprises have actively explored the application of high solid resins. For example, high solids resins from Bayer in Germanymagne are used as raw materials, with a resin mass fraction of 98%, a small amount of solvent and corresponding coupling agents. The accelerator is applied with several knives and solidified at a certain temperature. to form a surface layer, a foamable middle layer and an adhesive layer to achieve the feel and strength of real leather while dramatically reducing solvent usage. However, due to the high cost of synthetic leather produced with high resin content, there has not been a major breakthrough in the application of this type of synthetic leather in automotive interiors at home and abroad. stranger.

5. 4 Ultrafine fiber PU automotive interior leather

With the development of superfine fiber technology, many domestic manufacturers are able to produce ultrafine fiber PU synthetic leather, it uses ultrafine fiberss with similar structure and properties to collagen fibers bundled in natural leather to create a high-density non-woven fabric with a three-dimensional network structure. It is treated with PU resin with excellent filling performance and open microporous structure. do. This type of PU synthetic leather is very similar to natural leather in appearance, mechanical strength, elasticity, chemical resistance and stability, and it is also very light and thin. Microfiber enterprises in China, Japan, South Korea and other countries have already carried out research and development in this field and are currently actively promoting it in the automobile field, expanding the application of leather synthetic PU microfiber in the field of automotive interior leather [6].

6 Circular development economy of automobile interior leather

With the progress of sawnce and technology, the society is more concerned with cleaning and saving Production imposes higher and higher demands, and the development of the circular economy has become the goal pursued by enterprises. With regard to the disposal of scrapped vehicles, European legislation requires car manufacturers to be responsible for the disposal of all scrapped vehicles by 2006. At least 85% of the total mass of the vehicle must be recycled and the remaining 15% must be recycled. landfilled

These two proportions will be 95% and 5% respectively by 2015.

To Currently, some domestic metallic materials can be fully recycled, while non-metallic materials include seat and interior materials. Due to the high cost of recycling and the complex recycling process, it is difficult to recycle P U. There is no technologicalie mature for automotive synthetic leather and sustainable production recycling is almost zero.

It is known that a large foreign automobile leather manufacturer has developed and put into production a soft PVC resin recycling device, which adopts V i n y L o o p batch process , which can be used from 10,000 t/a 8,500

t/a P V C are regenerated from plastic waste (mainly composed of P V C). This technology uses a butanone blend to dissolve PVC and its additives under pressure at 100-140°C, then uses centrifugal precipitation to generate homogeneous soft PVC, into which the butanone blended solvent can be recycled. The PVC resin recovered by the device has high purity and can continuously produce PVC artificial leather, thus realizing the circular development economy of PVC artificial leather. Can PU synthetic leather learn from recyclingPV synthetic leather methodC, the development of circular economy, in order to achieve the recovery of PU leather waste and transform it into treasure, is also an important research topic today.

7 Conclusion

In recent years, China\'s production and quality of PVC artificial leather and PU synthetic leather have been improving. are improved. Significant progress has been made, especially in the production and scale of PU synthetic leather, which ranks first in the world. However, the current domestic application of PU synthetic leather mainly focuses on low-tech, low-value-added products such as bags, shoes, boots and stationery. With the increasing demand for PU synthetic leather for automobile interiors, domestic PU synthetic leather manufacturers must seize the opportunity of the increasing demand for PU synthetic leather for automobile parts, attach importance to technical research, strengthen independent innovation capabilities, master core technologies and take action. Actively explore PU synthetic leather. For the application of synthetic leather in automobile interior products, new materials and new processes have been continuously developed to establish an independent domestic PU synthetic leather brand with core competitiveness in the field of automobile interior applications.

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