Why do masks smell? What kind of mask has no odor?

Causes of odor of Xiamen bottle technology decryption mask

At present, there are always consumers complaining about the odor in non-woven mask. Through consumers' evaluation of non-woven mask, the major mainstream brands of Tmall, it can be concluded that the serious odor of masks is a pain point that needs to be solved urgently at present, and it is also the demand point of consumers.

So what is the cause and effect of mask odor?

1? Let's talk about raw materials first.

The material of mainstream non-woven mask is PP non-woven fabric. ? The raw material of PP nonwoven fabric is polypropylene. Polypropylene nonwoven fabric is made by stretching polypropylene particles or powder. ? The physical and chemical properties of polypropylene can be seen from the following figure.

It turns out that polypropylene is tasteless and nontoxic. Then the question is, why does the mask taste?

For raw material polypropylene pellets, the production process of polypropylene pellets involves many technical requirements. Generally speaking, polypropylene particles produce odor due to their own degradation and the use of various additives in the production process (paper reference: China Library ClassificationNo. TQ325 of Luoyang Petrochemical Polypropylene Co., Ltd.14). As for the odor component, it will be mentioned below.

So far, we have come to the conclusion that the odor of the original mask is due to the odor of non-woven fabrics, and the odor of non-woven fabrics is due to the odor of its raw material polypropylene particles.

So can we improve this problem? The answer is yes, China has a high level of technology in the field of polypropylene, and the quality of polypropylene granules of Sinopec and PetroChina is very good. Foreign ExxonMobil polypropylene granules are also quite good. Of course, the reason of mask odor is not only the problem of raw materials. It will be mentioned step by step below.

So far, we have come to a preliminary conclusion that improving the source of raw materials can improve the odor problem of raw materials. My point is: there are many non-woven fabrics factories in China, and there are also many companies that produce polypropylene particles. Find a non-woven fabric manufacturer with excellent technical level and strict requirements on the source of polypropylene particles (large petrochemical enterprises such as PetroChina, Sinopec and ExxonMobil). Only in this way can we produce non-woven fabrics with low odor.

However, there are few domestic nonwoven suppliers who can do both at the same time. Because for the whole non-woven fabric industry, the number of non-woven fabrics used in masks is not much. Other occasions using these non-woven fabrics do not require high odor grade, so the low-priced polypropylene raw material particles are "acceptable". I have consulted people in the nonwoven industry. Due to the fierce competition in the non-woven fabric industry, the profit of one ton of non-woven fabric has actually decreased to about 654.38+10,000 yuan. Choose good polypropylene raw materials, add 500 yuan to the cost of one ton, and directly cut off 50% of the profits. ? Therefore, customers will not increase this part of the cost unless they explicitly require the use of good polypropylene raw materials. ? The end result is the odor problem caused by these non-woven fabrics used on masks.

So let's start with the second point. As I mentioned above, why do nonwoven suppliers need their own excellent technology besides excellent raw materials?

As for polypropylene particles, polypropylene will break the chain above 150℃ and generate a series of oxidation products, which is only one of the sources of odor. Improper use of additives and catalyst residues. , will produce peculiar smell. To control odor, efficient volatilization equipment is needed, the dosage and types of additives are controlled, and the catalyst residue is controlled, which will not be described in detail. (Reference Paper: Ningxia Engineering Technology? 20/KOOC-0/June 3/KOOC-0/2 No.2)? Therefore, suppliers with considerable scale and technical conditions are needed. ? In the process of long-term contact, I learned that excellent non-woven suppliers have their own unique processing methods to reduce this problem.

So far, we have come to the conclusion that with excellent granular materials, we must also have excellent granular processing technology to ensure that the produced PP nonwoven fabric has the level of "low odor". ? I found that there are only two kinds of low-odor nonwoven products in China.

Next, let's study, if I get the excellent "low odor" non-woven fabric, can I solve the problem of mask odor? ? The answer is no.

First of all, the non-woven fabric itself has a strong ability to absorb the surrounding odor. Non-woven fabrics will smell if they are stored and transported improperly. This involves that manufacturers need at least a separate warehouse to store non-woven fabrics, and they should keep them well, moisture-proof, mildew-proof and moth-proof. This is the first point.

Second, assuming good storage and transportation, is the mask odorless or odorless? There is still a long way to go. ? So let's say, what is still affecting the smell of non-woven fabrics? -Make it!

The third point is production. This is an important link that cannot be ignored!

At present, the forming process of non-woven fabric is ultrasonic welding, and we can only use this method before other processing technologies come out. So will this treatment have an impact on the odor problem? The answer is yes.

Then let's talk about what kind of influence it is.

Let's take a look at some pictures (table 1 reference papers: materials science and technology 2004,11(3): 31-314).

That is to say, when the temperature is higher than 420 degrees, polypropylene is completely decomposed, and oxidation reaction is doped in the decomposition process, which will produce a series of irritating gases. ? However, the instantaneous temperature of ultrasonic welding cannot be measured, and the views of the insiders are as follows.

It can be roughly understood that the temperature range of "several hundred degrees or even higher" should cover the critical temperature of decomposition of polypropylene. This product will have a pungent oily smell.

Because this temperature can't provide valid papers and experimental data to testify, its reliability is not very high. Then let's look at a set of pictures. What are the odor components mentioned above? (Reference in the following figure: Henan Chemical Industry, 2008,24 (11): 43-45)

In the presence of air, more precisely, in the presence of oxygen, polypropylene begins to thermally oxidize at 150 degrees, producing so many odor gases. It is worth mentioning that non-woven fabrics, that is, polypropylene, must be melted during ultrasonic welding, and the melting temperature of polypropylene is shown in the following figure:

That is to say, the welding temperature of the mask should be kept at least above 160 degrees, generally 240 degrees for welding. ? As long as the mask can be welded, it must have a thermal oxidation temperature higher than 150 degrees. (Generally, 240 degrees welding is just the ideal thermal oxidation temperature), thermal oxidation products will be produced, and many small molecules with peculiar smell will be produced. ? If the temperature is not well controlled, as mentioned above, it will completely decompose. Produce a pungent oily smell.

In addition, some factories are used to ultraviolet disinfection out of kindness, but ultraviolet rays will destroy the chemical bonds of polypropylene, and then combine with oxygen to produce aldehydes, ketones and other substances. So some sellers often say that this is the smell of disinfection. Ultraviolet disinfection of non-woven fabrics can produce a taste, but disinfection is more toxic. Whether it is disinfected or not, there are many phenomena that all odors are disinfected. In fact, it is also a helpless move, because I don't know why there is an odor.

So far, we have come to the conclusion that there are the following reasons for the odor of masks.

1? Polypropylene particles, the raw material of non-woven fabrics, have peculiar smell.

2 improper production process of non-woven fabrics, non-woven fabrics have peculiar smell,

Improper storage and transportation of non-woven fabrics, limited factory environment, and odor in the space where semi-finished products are placed lead to the adsorption of environmental odor.

The production process is limited, and there are thermal oxidation and complete decomposition of polypropylene, resulting in odor.

At this point, let's study the key points in detail! Smell components of masks and their potential hazards.

First of all, polypropylene pellets, the raw material of non-woven fabrics, will produce harmful gases if they are improperly sourced (refer to Henan Chemical Industry, Volume 24, 2007).

Secondly, it is assumed that the polypropylene raw material has normal particles and low odor, and these harmful gases are generated in the production process of non-woven fabrics (hereinafter referred to as PP product processing).

(Reference: Ningxia Engineering Technology, Volume 12, Phase II)

Third: assuming that the first two do not exist, these gases will be produced in the process of making masks.

(Reference: Luoyang Petrochemical Polypropylene Co., Ltd. 47 10 12)

Through the study of these three parts, it is found that the main components of the odor on the mask are carbonyl compounds, formaldehyde, acetaldehyde, ketone, alcohol, acid, acetophenone and so on. These gases are collectively referred to as. VOCS？ There is no doubt that volatile organic gases are harmful to human body. ? Therefore, on the other hand, odor may be toxic.

Personal opinion: it is shocking to say that masks are poisonous, but there are so many journal articles, and this conclusion is drawn through experiments. A large part of the research results brought by these journal papers have been applied to the manufacturing process of non-woven fabrics. However, the technical requirements are relatively high, and few nonwoven manufacturers can do it. Non-woven fabrics have a wide range of applications, and these achievements may not be realized when applied to masks. In addition, some of these research results appear on the mask (I don't know whether it is intentional or coincidental), but few people systematically use these research results and provide solutions. At present, the proportion of masks that cause serious odor in the mask market is very high.

Masks are toxic, but whether the concentration of toxic gas components reaches the level that can endanger human health depends on the specific situation. If people can clearly feel that the odor in the mask makes them uncomfortable, disgusting and unacceptable, it is toxic to some extent. For professional reasons, I often wear a mask to feel the smell and resistance. I have rhinitis, and my nose is often blocked like this. I didn't know why my nose was blocked until I found these. And for a long time, my throat will still hurt. I inhale hard. I inhaled those gases.

Can the gas concentration inside the mask be determined by testing? Personally, it is more difficult! According to the national standard, the raw materials of masks must be harmless to human body, but I don't know if the raw materials are harmless, will it be harmful if we process them? Moreover, this point is only mentioned in the national standard, and there is no in-depth analysis.

These volatile gases in the mask are divided into two parts, one is the surface gas produced by non-woven fabrics, and the other is the welding gas produced by welding. Surface gas is easy to fill the packaging bag, and ventilation can remove some peculiar smell on the surface. ? Weld and other layers of cloth are wrapped and sealed in the inner layer, which can not be diffused in a short time, and the volatilization process takes a long time.

As a health protection product, I hope that the mask itself is harmless at first. Pregnant women and children, the elderly and the infirm can bear the lowest concentration, no matter how high or low, or even the best. I'm not alarmist. I know it myself.

Don't forget the original intention when making a mask!