Want what you see is what you get? Color difference control is indispensable!

Under certain conditions, customer complaints are of great value to enterprises, because enterprises can timely find the deficiencies and mistakes of products or services through customer complaints, so as to find the root causes and solve problems, and promote the continuous growth of enterprises.

Hongye quality control department will regularly analyze customer complaints. Through analysis, it is found that the color difference accounts for the largest proportion of customer complaints. At present, the major non-woven fabric production enterprises do not have a fixed standard for color difference, but compare it through the standard color card. Therefore, color difference is a common phenomenon in the production of non-ferrous spunbonded non-woven fabrics. The reasonable selection of color masterbatch composition and correct process control can control the color difference within a reasonable range to the greatest extent and improve the quality of products. So what is the reason for the color difference? How to avoid color difference? Please read the following analysis carefully!

01. When we were talking about color difference，

What are we talking about?

Hue determines what color is, which is the primary feature of color. In short, what color is at a glance is hue.

Purity determines the intensity of color. In short, it is saturation. The grayer the color, the less clear the color phase at a glance, and the lower the purity.

Lightness determines how bright the white light on the color is, that is, the sensory light is brighter and darker. In addition to simply adding black and white to change the lightness, different solid colors also have lightness differences. After removing different solid colors, you can compare the lightness.

02.What are the factors affecting color difference?

Changes in the properties of raw materials

Since the melt index of the raw material has a great influence on the fineness of the fiber, when the MFI changes greatly, if the addition amount of the color masterbatch is not adjusted accordingly, the product will appear color difference. If the MFI becomes larger, the color becomes lighter; if the MFI becomes smaller, the color becomes darker.

The impact of product structure

When producing SMS products, because the coloring requirements of the M-layer cloth are higher than that of the S-layer, and the coloring cost of the M-layer is also higher (the unit price of the colorant is high, the addition ratio is also large, that is, the dosage is also large), often in order to reduce costs. The amount of additives is reduced, so the color tone of the M layer cloth tends to be lighter than that of the S layer.

Since the color of the SMS product is the result of the addition of the colors of the multi-layer cloth, in this case, if the unevenness of the S-layer cloth is too large, the color difference of the product will also be the color of the product cloth with different shades of color. Spots appear; in the thin web position, the color of the product is lighter; and in the position with a larger fiber web basis, the color of the product is darker.

Due to the particularity of the structure of SMS products, even for products with the same total quantitative ratio, when the quantitative ratio of each layer of cloth is different, for example, when one is 7:3:7 and the other is 2:1:2, the cloth in each layer is different. In the case of the same proportion of color masterbatch added, the color of the product is also different, and there will be a phenomenon of batch color difference.

The same masterbatch, the addition amount of 1.5% is compared with the addition amount of 2.0%

In addition to the difference in color saturation, the amount of color masterbatch added will also cause serious visual hue differences. Sometimes customers complain that your color is not even the hue. What is the use of adding the amount? This situation is often caused by the wrong amount of addition. If the customer confirms that there is no problem with the hue of our color card, the color can be achieved by adjusting the added amount.

Since some color masterbatch manufacturers will add fillers such as calcium carbonate in consideration of cost when producing masterbatches, the bulk density of the masterbatch will increase. Hongye promises that all masterbatches will not add fillers. Relatively speaking, the bulk density It will be too small. If the non-woven fabric manufacturer uses the same machine and the same feeding screw speed to use the volume method to feed the material, it may take 10 revolutions for our masterbatch, and only 9 revolutions for other masterbatches, as if ours The amount of masterbatch added is high, which is not the case.

Fillers and Recycled Materials

Some customers will add some fillers when producing non-woven fabrics, and different brands of fillers will show different colors. The effect of adding filling on the color is not only a matter of depth, but also directly affects the hue. The cloth surface will be opaque and not bright, and the surface will be whitish.

The same masterbatch, without fillers and with fillers

It may also be caused by the introduction of additional recycling without controlling the quantity and color balance of recycled materials. Subjectively, it is possible that in the process of product color matching, because the production system has not yet entered a completely stable state, especially before the product color tone has not appeared stably, the products that are still in the transition state are regarded as normal products, and follow-up tracking The detection and comparison work cycle is too long (or too short), or even the timely detection is not carried out.

Typically, this change is more of a saturation change, i.e. the product will darken in color. This will make on-site color matching very difficult, and it is usually possible to pre-adjust (increase or decrease, but in most cases decrease) the addition ratio of color masterbatch based on experience for production. In this case, the color matching on the spot will be different from the sample, but after a period of time, the product will meet the requirements. However, in doing so, it is necessary to have the support of rich production experience, otherwise it is easy to produce large quantities of substandard products.

Production process and equipment

The input ratio of various color masterbatches is improper, and the process parameters (such as temperature, speed) are too different from the referenced products. In addition, it is also related to the product quantitative (large quantitative, darker color tone), fiber drafting degree (the more sufficient fiber drafting, the smaller the fineness, the optical refractive index will change, and the color tone will be lighter) and so on.

Different models and different equipment structures, such as four-component metering method (measuring cup or screw), stirring method (continuous or intermittent), melt channel length, hot rolling mill rolling point density difference, the relevant equipment of the production line has been Major improvements or repairs, etc. In this case, even if the proportion of the color masterbatch is the same, there will still be batch color difference.

Visual chromatic aberration caused by light source and observer

An object that does not emit light by itself can be perceived by people as having three conditions: the light source, the object, and the observer. When we visually observe the color of an object, it has a great relationship with the conditions of visible light. Different Under the light source, due to the spectral reflectance of the object, the observation environment and conditions, the observer's own visual color difference, etc., the color of the visually observed object will be different.

Therefore, when choosing a light source, try to choose the same type of light source that customers use when using this product. In the absence of special requirements, the international standard artificial daylight light source should generally be selected.