In recent days, a video called "Distinguishing the True from the False and Empty Filtering" has been madly transmitted on the X-ray platform, which contains two experiments. After the video was on fire, all the "big V’s" parrot the same video. -What did you say in the video? Let’s watch (in order to save traffic, let’s take a simple screenshot)!
Experiment 1: Take two pieces of air filter, put them flat on the table, apply iodophor (or iodine) on the surface of air filter paper, and observe the color change of iodophor after a few seconds. If iodophor doesn’t change color obviously, it still shows yellow, which means that the filter paper is genuine. Conversely, if the iodophor turns black, it means that the filter paper contains starch, which is a fake.
Experiment 2: Take two pots filled with water, completely soak two pieces of air filter in water (the water has not been filtered by air at all), leave it for a few minutes, take the air filter out of the water and spin it dry, and observe the state of the filter paper. If the whole filter paper is still firm, it means that the air filter is genuine; If the filter paper has been infiltrated by water and become soft, it is a fake.
Identification experiment of "starch air filtration" by network transmission
And various "principle explanations"
According to the video, it is said that it is because the filter paper contains starch that it changes color after touching iodophor. So why does the filter paper contain starch? Rumor has it that the filter paper that softens when it meets water is cotton pulp paper, while the strong one is wood pulp paper. Starch needs to be added to cotton pulp paper to increase its strength.
It is also said that the filter paper treated with cotton pulp paper and starch is "semi-adhesive paper"; The pure wood pulp paper is "all-adhesive paper" … There is even an exaggerated saying that "the residual gum in the engine oil pan is the residue of starch in the filter paper after the automobile is filtered by inferior machinery" …
Truth: Cotton pulp paper is n times more expensive than wood pulp paper.
Almost all paper contains starch.
At that time, many car enthusiasts came to ask me, which made me laugh and cry! First of all, I want to say, "Today’s self-media is so unreliable"? On the question of which is more expensive, wood pulp paper or cotton pulp paper, even if you don’t understand it, can’t you ask the children around you who are learning to draw? -please! Is cotton pulp paper n times more expensive than wood pulp paper? ! You should brag like a little these days!
Since the "cheap wood pulp paper" is untenable, it seems that the "starch theory" should also be untenable, right? In fact, if you go home, try iodine on your children’s books, exercise books, newspapers and magazines: they all change color! This means that almost all paper contains starch to some extent.
So why do you use starch in papermaking? Consulting the engineers in the paper-making industry, it is known that starch used as sizing material in paper-making can improve the paper quality and papermaking conditions, and make the paper smooth, easy to print, wear-resistant and grease-resistant, with a certain drying strength and low cost. Therefore, the whole paper industry mostly uses modified starch as "retention/sizing agent".
The real filter paper adopts "mixed pulp paper"
The process is divided into "curing" and "non-curing"
In fact, the same is true of filter paper. First of all, the filter paper is made of "mixed pulp paper", including softwood pulp, hardwood pulp, Chinese alpine rush pulp and cotton pulp. It is not the "single pulp paper" rumored in the market. Secondly, because the filter paper is under pressure for a long time, we must find ways to improve the strength of the filter paper, otherwise it will rot easily. Therefore, industrial filter paper must be treated by "impregnation" process!
According to different processes, it can be divided into two categories: cured filter paper and non-cured filter paper. Cured filter paper is generally impregnated with phenolic resin, and then baked at 150~180 degrees for about 15 minutes to cure the resin and increase the stiffness of filter paper. Here, the "solidified filter paper" came out!
"Cured filter paper" is almost completely covered with resin because of high temperature treatment, so the water absorption is very poor (which is a good thing). The starch is locked inside, so iodine can’t touch the starch, so iodine doesn’t change color when doing experiments. What about "non-solidified filter paper"?
"Non-curing filter paper" generally uses polyvinyl acetate resin as impregnating agent, and it will be finished naturally after impregnation. Therefore, the hardness and stiffness of filter paper are not as good as that of "solidified filter paper". Moreover, "non-solidified filter paper" is easy to absorb water and become damp, and its high temperature resistance is not as good as "solidified filter paper".
"Curing" is better than "non-curing"
But the latter is completely sufficient for air filtration.
In other words, the materials of these two types of filter paper are the same, but the subsequent impregnation process is completely different! -"Cured filter paper" is obviously better? ! -that’s right! But the price is also expensive! Therefore, only "solidified filter paper" is allowed to be used in mechanical filter products; For air filtration, "non-solidified filter paper" is completely sufficient.
You may have to refute it: the experiment said that "uncured filter paper" is afraid of water. How can it be used for air filtration? In fact, think about it, the air intake of the automobile engine sucks in air, not soaked in water! Moreover, the air inlet of a reasonably designed car has a perfect rain-blocking structure and drainage structure, and raindrops will not touch the air filter (last year, Honda’s engine collapsed and stalled in a rainy day, wasn’t it because of the structural defect of "rain-blocking"?
The same brand of filter paper may not be the same material.
Consumers should try to find formal channels to buy.
After a full demonstration, the air filter manufacturer came to the conclusion that "non-solidified filter paper" can not be used in mechanical filter, but it is completely sufficient for air filter-of course, the price is much cheaper. Therefore, at present, you can easily find the versions of "non-solidified filter paper" and "solidified filter paper" at the same time, although they may be the same model products.
In fact, this truth is the same as tires: some Michelin tires made in Shanghai use 2-layer curtain wiring; The products of Shenyang factory with the same model and specifications are wired with 1 layer curtain. -Although they have different structures, they all meet the performance indicators stipulated by enterprises. Can you tell which is "genuine" and which is "fake"? We often read in the manual that "the parameters are subject to change without prior notice" actually means this.
No, it was publicly measured on the Internet. Didn’t the original air filter bought from the 4S shop "turn over the car" under iodophor? -In fact, nowadays, due to cost reasons, major air filter manufacturers have increased the output of "non-solidified paper" air filters (and this paper has less pressure on the environment during production and is easier to protect the environment).
So again, if you are afraid of encountering counterfeit goods, try to choose a reliable platform as much as possible. For example, the manufacturer’s own sales network or the well-known platforms officially authorized by the manufacturer are usually reliable. -finally, be naughty: nowadays, many white air filters are made of PP electrostatic cotton, and there is no starch. No matter whether it is true or not, iodine does not change color. How can I tell the difference? -Finally, I would like to advise those online celebrity big V: Make clear the context before releasing information, and don’t create pseudo-scientific remarks all day long just to catch your eye! !