Along with the rapid development of the non-woven industry, it has also driven the development of the required dressings, and adhesives are one of them. In the production process of non-woven fabrics, the role of adhesives is to reinforce the non-woven fabric or to finish the coating after product formation. In addition to the adhesive based nonwoven process, needle punched nonwoven fabrics and sewn nonwoven fabrics also require surface coating or impregnation treatment with adhesives to stabilize the shape and size of the product, improve its strength, stiffness, and other special properties. In other words, the performance of the adhesive largely determines the appearance and intrinsic quality of the final product. Industry insiders say that developing high-quality, high-performance, functional, and specialized green and environmentally friendly adhesive products is an urgent task for domestic nonwoven adhesive manufacturers and research institutions.
Products that meet both mechanical and environmental protection indicators are highly valued
The vigorous development of disposable non-woven fabric products and washable wet wipes has put forward higher requirements for adhesives – non-woven fabrics must maintain a certain adhesive strength during use, and once discarded, they must be in a loose state in the sewer to ensure smooth drainage. This means that adhesives for non-woven fabrics will develop towards a direction that simultaneously balances mechanical strength and environmental performance.
At present, the most commonly used and developed adhesive in non-woven fabric production is water-based adhesive, which includes two categories: water-soluble and water dispersible. This type of adhesive has attracted widespread attention from researchers and enterprises both domestically and internationally due to its advantages of non flammability, non toxicity, low cost, easy removal, and no fire hazard during storage.
However, despite the good development trend of adhesives for non-woven fabrics in China, there are still many problems that need to be solved urgently, the first of which is the dispersion of production enterprises, outdated technology, and low quality and grade. According to incomplete statistics, there are nearly 500 non-woven adhesive production enterprises in China, distributed in 28 provinces, autonomous regions, and municipalities directly under the central government, but there are only 20 large-scale and high-level enterprises.
Secondly, problems such as product aging, slow updates, and inadequate application research and after-sales service still exist. Most companies can only compete for the market through low price competition of old products. For example, polyvinyl alcohol formaldehyde adhesive, mainly used for building reinforcement materials and other structural reinforcement materials, has been banned in developed countries due to its free formaldehyde content, which is harmful to human health. However, its current usage in China is still relatively large.
In addition, there is a shortage of main raw materials and related additives for some non-woven adhesives, which cannot be produced or the product quality and performance cannot meet the requirements. The problem of some additives that are matched with adhesives having to be imported in whole or in part from abroad is also very prominent.
With the increasing call for environmental protection and the improvement of environmental regulations, environmentally friendly adhesives for non-woven fabrics have gradually become the mainstream of development. The future development of adhesives mainly reflects two aspects: one is the transition from solvent based to water-based and solvent-free. Traditional adhesives widely use toxic, harmful, and volatile organic solvents such as benzene and toluene, which pollute the environment, harm human health, and pose risks of combustion and explosion. However, water-based and solvent-free adhesives are non-toxic, safe, and environmentally friendly, and will be the mainstream products in the future market demand. The second is the transition from low formaldehyde emissions to zero formaldehyde emissions. Formaldehyde poses a huge threat to human physical and mental health. Although low formaldehyde emissions can be achieved through methods such as adding formaldehyde capture agents, adjusting ingredient ratios, and improving polymerization processes, the exit of formaldehyde condensation adhesives from the historical stage is an irreversible trend.
From the perspective of specific implementation processes, the development of adhesives for non-woven fabrics will pay special attention to the modification of natural adhesives, the development of low formaldehyde or formaldehyde free coating finishing adhesives, and the development of low-temperature cross-linking adhesives.
Targeted treatment to meet multiple performance requirements of products in different fields
The requirements for production environment and adhesives vary among products in different fields. Based on the required product performance, selecting cost-effective adhesives and production processes can ensure the quality characteristics of the product, save costs, and achieve energy conservation, consumption reduction, and green production.
Flocked interior – synthetic resin lotion
In the electrostatic flocking printing process, the adhesive is uniformly applied to the surface of the non-woven fabric through a scraper type applicator. Based on this, after multiple startup tests, it was found that the adhesive used for electrostatic printing flocking must not only have the performance of general electrostatic flocking adhesives, but also meet the following five special requirements. One is that the adhesive must have higher twist and thixotropy. The twist should generally be around 30pa · s~35pa · s, and there should be no “flow collapse” phenomenon at room temperature; Secondly, the adhesive must have higher tensile strength and bonding strength with the base fabric and fluff; Thirdly, the adhesive must have rheological properties where viscosity decreases as quickly as possible with shear rate; Fourth, the particle size of lotion of adhesive should be fine and uniform, the stability of lotion, especially the mechanical stability, should be as good as possible, and the film forming time of lotion should be appropriately longer; The adhesive must be absolutely clean and free of any mechanical impurities.
At present, most imported flocking machines used in China adopt a two-stage sizing process, while domestically produced flocking machines generally use a one-time sizing process. The adhesive that can meet the process requirements of two kinds of equipment is recommended to use synthetic resin lotion, especially polyacrylate lotion adhesive. This type of adhesive is not only soft, but also easy to adjust.
Synthetic leather – hot melt adhesive
The improvement of synthetic leather technology for shoe materials and the continuous emergence of various high-performance adhesives have greatly increased the proportion of synthetic leather bonding method shoes in the footwear industry, and some shoes even do not require sewing manufacturing at all.
At present, in terms of shoe materials, the most widely used and rapidly developing adhesive for non-woven fabrics by domestic and foreign enterprises is hot melt adhesive, which is commonly divided into two categories: polyamide and polyurethane. When using polyamide hot melt adhesive to stretch the upper, due to the relatively low viscosity and good flowability of polyamide in the molten state, it can almost adhere to all shoe upper and shoe lining materials. The temperature for using this hot melt adhesive varies depending on the process used, generally ranging from 150 ℃ to 180 ℃. When processing non-woven imitation leather shoe materials with polyester hot melt adhesive, the polyester hot melt adhesive should be heated and melted in a melting storage tank first. Then, a metering pump should be used to transfer the melted adhesive from the storage tank to the heated nozzle, and the adhesive should be sprayed onto the bonded sole through pressure. Production practice has proven that leather shoe soles bonded with polyester hot melt adhesive will not peel off even after 75000 cycles of repeated bending. In addition, the cost of hot melt adhesive is relatively low, which is beneficial for enterprises to ensure profits.
In the case where the adhesive is determined, the operation technique and method are the decisive factors for the success or quality of the bonding, among which the coating method, adhesive layer thickness, drying time, bonding pressure, environmental temperature and humidity control are extremely important.
Filter felt – hot melt adhesive
Hot melt adhesive is usually chosen as the adhesive for filter felt. At present, there are many types of hot melt adhesives in the domestic market, with representative products including polyethylene series, acetic acid vinyl acetate copolymer system, polyamide series, polyvinyl chloride series, etc. The main body of the hot melt adhesive used for filter felt is thermoplastic resin, which is melted by heating and solidified at low temperatures, and has adhesive properties. If these resins do not consider their commonalities and utilize their respective characteristics, various hot melt adhesives with different properties can be produced.
When choosing the type and parameters of hot melt adhesive for filter felt, it is necessary to consider and determine the process parameters of the hot melt adhesive based on the type, material, structure, quality, and finishing method of the fabric and adhesive lining base cloth, and select the technical parameters of the hot melt adhesive according to various coating methods. For example, factors such as the bonding temperature range between the filter felt base fabric and the fabric, as well as the melting characteristics of the hot melt adhesive. When the bonding conditions exceed the range, problems such as leakage or bonding strength may occur. Therefore, even if the processing conditions are constant and the materials are different, it is necessary to adjust the bonding temperature and pressure. In addition, due to differences in the conditions of using a hot press, the results may also vary. Therefore, testing must be conducted before using the hot fusion machine.
Needle punched carpet – synthetic rubber latex
The adhesive used for needle punched carpets must have good bonding performance, good operability, easy to increase adhesion, good mechanical stability, good chemical stability, odorless and tasteless properties. The adhesive used for needle punched carpets is generally synthetic rubber latex, with carboxyl styrene butadiene rubber being particularly recommended. This type of adhesive has the advantages of simple configuration, good stability, and long-term storage, especially suitable for needle punched carpets.
In order to adjust the solid content of adhesives and reduce costs, it is often necessary to add a large amount of fillers, which requires latex to have high adhesion and stability. Moreover, fillers are usually added in a dry state, so latex is required to have high dry filling properties and low foaming properties. Latex with a surface tension of 30 × 10-5N/cm~60 × 10-5N/cm is generally suitable. In addition, combining different monomers and adjusting the dosage ratio to combine lotion can obtain adhesives with different properties and soft and hard hand feel. In practical use, the optimal selection can be based on fiber type, usage requirements, and price cost.
In the processing of needle punched carpets, the back coating adhesive process not only affects the appearance and performance of the carpet, but also affects the service life of the carpet. In the domestic market, there are three processes for carpet gluing: single-sided gluing, jute backing and foam backing.
Spray adhesive cotton – vinegar acrylic adhesive
Spray adhesive cotton is one of the essential raw materials for protective reinforcement materials. In addition to fiber variety, quality, processing methods, and conditions, the most important factor affecting the quality of spray bonded cotton is the adhesive. The quality of the adhesive used for spray bonded cotton directly affects the quality of the product. At present, adhesives commonly used by domestic enterprises for spray bonded cotton include acetate acrylic adhesive, solid polyacrylate lotion adhesive and other categories.
Based on production experience, mist spraying is the most suitable method for vinegar acrylic adhesive. In this way, the fiber mesh structure is not easily damaged and the coverage is uniform. The penetration depth of the adhesive into the fiber mesh is generally controlled at 60% to 70% of the thickness of the floc, and the middle fiber layer can also be bonded to improve the peel strength. The rubber material is made of non hydrophilic materials, which ensures good water washing performance of the cured product. After washing, it will not deform or loosen, and can naturally recover to its original state after sun drying. It should be noted that the amount of glue sprayed is related to the softness, texture, strength, breathability, and other properties of the finished product. Spraying too much can make the product harder and less elastic; Poor adhesion between fibers due to insufficient spraying. Therefore, the solid content and adhesive amount of the adhesive depend entirely on the requirements of product quality.
Dongguan Liansheng Non woven Technology Co., Ltd. was established in May 2020. It is a large-scale non-woven fabric production enterprise integrating research and development, production, and sales. It can produce various colors of PP spunbond non-woven fabrics with a width of less than 3.2 meters from 9 grams to 300 grams.
Post time: Mar-10-2025