The sky is falling! My favorite fleece pants in winter are actually poisonous?

Recently, the content about composite fleece pants being "toxic" has caused heated discussions on short video platforms. The video says: "The composite fleece fabric is glued together, has a high formaldehyde content, and is toxic, so don't buy it." Many netizens are worried about this and left comments saying: "If you don't buy fleece fabric, how can you survive this cold winter!"

So, are composite fleece fabrics really toxic?

Let me give you the answer first: as long as it is produced in a formal manner and the clothes have the mandatory safety implementation standard GB18401-2010 "National Basic Safety Technical Specifications for Textile Products" on the tag (infant and children's clothing is subject to the mandatory standard GB31701-2015 "Safety Technical Specifications for Infants and Children's Textile Products"), there is no need to worry too much.

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What is "composite velvet"?

If you want to understand what "composite plus velvet" is, you must first know what "composite" is.

Compounding, as the name implies, is to combine two different fabrics together. It is a process that is widely used in clothing processing. For example, the popular jackets nowadays are not only compounded once, but usually twice to form a three-layer composite fabric, which can achieve the effect of protecting against rainwater outdoors and expelling moisture from the body. Some fabrics with three-dimensional decorative effects are also achieved through compounding technology.

In addition, the fabrics we wear daily are difficult to make thicker when the weight reaches 300g/㎡. However, the warmth and thickness of clothes are closely related. The thicker the fabric, the warmer it feels. Therefore, we can choose to bond two relatively light and thin fabrics together to make it thicker and warmer.

As for "composite plus fleece", it usually refers to combining a certain fabric with polyester fiber (that is, "polyester" as we often call it, and the fabric made of it is made into coral fleece, polar fleece, lamb fleece, flannel and other styles through napping process), and then compounding it with thermal underwear fabric. For example, the thermal underwear plus fleece series we often see is to compound the outer layer of normal fabric with the inner layer of furry fabric.

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Does the glue of composite fabrics contain formaldehyde?

There is a saying that "there is no glue without formaldehyde". This is because most of the glues we used in the past were urea-formaldehyde resins and phenol-formaldehyde resins, especially those used to bond boards, which left everyone with the impression that glue and formaldehyde are strongly related.

However, there is usually no concern about formaldehyde release from the glue used in the composite process of bonding two fabrics together. Because the composite of fabrics must ensure a certain degree of softness, urea-formaldehyde resin and phenol-formaldehyde resin are high in hardness and are usually not used.

The bonding of composite fabrics currently uses two types of adhesives: hot melt adhesive and oil adhesive:

1. Polyurethane hot melt adhesive

The most commonly used hot melt adhesive in the clothing field is polyurethane hot melt adhesive (abbreviated as TPU or PUR hot melt adhesive), which is characterized by good bonding strength, the material itself is very soft and elastic, has good heat resistance and water resistance, and is suitable for use in the clothing field. After compounding, it has little effect on the softness of the fabric, and it will not decompose formaldehyde, meets safety standards, and is relatively expensive.

Hot melt adhesives are also used in many scenarios in clothing and textile processing:

Common business shirts use a lot of fusible interlining to make the clothes more three-dimensional, crisp and stylish;

The seams of down jackets are pressed with hot melt adhesive strips instead of sewing threads, which improves down-proof and waterproof performance.

Hot melt adhesive is also used in medical protective equipment such as protective clothing and masks, and even more hot melt adhesive is used in the production of footwear.

Therefore, there is no need to panic about composite fleece clothing that uses hot melt adhesive. Products that comply with national safety technical specifications are safe for the human body.

2. Oil glue

Some cheap manufacturers will use "oil glue", use organic solvents to dissolve the glue, and let the container evaporate and stick it after compounding. This kind of oil-glue composite fabric is not very safe and environmentally friendly. Although it does not contain formaldehyde, there will be residues of volatile organic solvents.

You can easily distinguish this by smelling the product after receiving it. If you find that it has a pungent smell that makes you unpleasant, you can just return the product and refuse to accept it.

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In addition, the thermal clothing made using the composite process has increased the thickness of the composite fabric, and its warmth retention has been greatly improved, but some of the pores between the fabrics are also blocked by glue, which will have a certain impact on the breathability of the clothing. It may not be very comfortable to wear, but it is relatively cheap.

Summarize

Fleece-lined clothes are glued together, but you usually don't need to worry too much about issues such as formaldehyde, but if the product has a pungent odor, you must purchase it with caution.

The main reason for the popularity of composite plus fleece underwear is that it can provide a warmer wearing feeling with very low production cost, but it is also easy to cause sweating and static electricity, which usually appears in mid- and low-end thermal underwear products. If you want to pursue a more comfortable thermal experience, it is better to choose non-composite thick thermal underwear, which is better to blend acrylic, regenerated cellulose fiber and spandex.

Planning and production

Author: Yao Weiming, Textile Chemical Engineer

Audit丨Song Lidan Consulting Engineer, Industrial Research Department, China Textile Construction Planning Institute