1 Review and review
Proper examination and review of samples are the prerequisite for the correct formulation of the production process.
1.1 Examination of orders
The so-called "review of a single bill" means that before a production process is formulated, it will earnestly "interpret" the production contract or processing agreement signed by the company and the merchants. Each of the articles in the contract or agreement must be carefully studied, and it must be accurately understood. If the "single review" is wrong, the production process will inevitably be wrong. Once the wrong production process is implemented, it must cause a major accident.
There are examples for:
Due to the “single review†of a certain company, a company used a high-temperature and high-pressure (130°C) method to dye the nylon cotton fabric as a polyester-cotton fabric. As a result, the entire three-cylinder fabric (5,000 meters) was scrapped and suffered heavy losses.
Everybody knows. Although polyester and nylon are synthetic fibers, their dyeing properties are quite different. Polyester, because his macromolecule chain is straight and has no side chains, the linear state is good, and macromolecules can easily move closer together. Therefore, the overall degree of good crystallinity is good and the structure is tight. In addition, polyester macromolecules have no strong hydrophilic groups and are highly hydrophobic (absorbing only 0.4%). Therefore, polyester fibers are difficult to swell (Tg=75°C) and must be swelled under high temperature (125-135°C) conditions.
Nylon and polyester are different, nylon structure is much looser than polyester, and its molecular structure also contains many -NH and -COOH (absorbing center), so the moisture absorption rate of nylon is 10 times larger than polyester (4%). The glass transition temperature is also much lower (nylon 6 Tg = 35-50 °C), so the fibers of the nylon tend to swell and require only 100 °C for dyeing. If 130°C dyeing is used, because the temperature is too high, the "viscous flow state" temperature of the nylon is already approaching or reached, so the nylon fabric will generate "paper" (clear, strong, stiff, yellowish) and lose its use value. . (Note: The test shows that the maximum heat-resistant upper limit of nylon 6 is l20°C. If it is greater than l20°C, it will be marked by paper).
The practical experience tells us that the following points must also be taken into account when examining orders.
(1) Merchants attach great importance to the intrinsic quality of the product (color fastness), so the order of color fastness is clearly stated in the order, but the applicable fastness standard is not specified. The standard of fastness implemented by customers is whether it is GB China National Standard or IS0 International Organization Standard; it is the standard of CEN European Standardization Committee, or AATCC American Textile Chemist and Dyers Association Standard; is the standard of ATTS Japan Fiber Products Technology Association, or ASAC Asian Standards Advisory Committee Standard. Because of different standards, detection methods and expression methods are different, and the results are naturally different, and there are even greater differences. Therefore, it must be clear about the standards of firmness that customers implement. Otherwise, due to different implementation standards, there may be disagreements with the merchants and they cannot deliver on time.
For example, light fastness is usually enforced by the lS0 international standard (equivalent to the GB China standard), but some merchants implement the AATCC US standard. The IS0 international standard is an eight-level system, with the worst grade one being the best. The AATCC U.S. standard is a five-level system, with the best one and the worst. That is, AATCC standard l is equivalent to IS0 standard l.6.
If the merchant's requirement for light fastness is 3+ (level 3 or higher) and the standard of execution is the lS0 standard, the requirement for moderate lightness can be achieved. If the implementation of the AATCC standard (3 + level is equivalent to the IS0 level 5), the requirements are too high, it is difficult to produce deep shades to achieve compliance.
There are two reasons:
First, the deeper the color, the better the light fastness, the lighter the color, the worse the light fastness.
The second is that 95% or more of the reactive dyes have poor light fastness (especially light-colored dyes). Only a few dyes have good light fastness, and light-colored dyes can reach IS0 level 5 or so. Such as the Huntsman company's impregnated shallow primary colors: active yellow FN-2R, reactive red FN-2BL, active blue FN-R; Taiwan Yongguang's padding primary colors: active yellow C-GL, reactive red C-3B, active blue C-BB and so on.
Therefore, for the light fastness in a contract or agreement, it is necessary to clarify the implementation standards and must not take it for granted. Because once the IS0 standard is regarded as the AATCC standard, it will cause improper light fastness due to improper dye selection, resulting in big mistakes.
(2) Light fastness includes two types:
1 Ordinary light fastness (light fastness) refers to the degree of fading discoloration of dyeings after exposure to sunlight.
2 The light fastness (combination fastness) refers to the degree of fading and discoloration of dyeings in sunlight in the presence of artificial sweat. Due to the dual effects of sunlight and sweat, the dyes have a much lower light fastness than normal light fastness.
Comparison of ordinary light fastness and sweat-light fastness
Fastness to sunlight
(IS0.105-B02
standard)
Khan-light fastness
Acidic
Alkaline
Reactive Yellow C-GL
5-6
4-5
4
Reactive Red C-3B
5-6
3-4
3
Reactive Blue C-BB
5-6
3-4
3
Note: The dye depth is 0.5% (o.w.f)
Therefore, the degree of light resistance in a contract or agreement refers to the ordinary light fastness or the light-fastness. It must be clearly distinguished and must not be confused.
(3) In recent years, there are more and more orders with chlorine fastness requirements. It is worth noting that there are two kinds of chlorine fastness:
The first is the fastness to chlorine bleaching, and the second is the chlorine fastness. Although both represent the ability of dyes to withstand effective chlorine oxidation, their detection conditions vary widely.
The chlorine fastness fastness refers to the degree of fading discoloration after treatment for 60 minutes after dyeing the sample with a solvent ratio of 1:50, available chlorine of 2 g/L, pH of 11±0.2, and a temperature of 20° C.±2° C.
Chlorine-impregnated fastness refers to the degree of fading discoloration after 60 minutes of treatment when the dyeing sample has a dissolution ratio of l:100, available chlorine (20, 50, 100 mg/L, third gear), and a temperature of 27°C ± 2°C.
Because the available chlorine concentration of the test solution is very different, the test results of the two are completely incomparable. Therefore, the requirements for chlorine fastness proposed by customers must be clearly distinguished and must not be confused.
In the export color sheets with the requirement of chlorine fastness, except that some medical work clothes fabrics have chlorine bleach fastness, most of them refer to chlorine fastness. It is worth noting that there are three levels of chlorine fastness testing methods, namely available chlorine concentration 20mg/L, 50mg/L, 100mg/L. The effective chlorine concentration in the third stage is different, and the test results are certainly not the same. Therefore, it is necessary for the merchant to determine the fastness to chlorine fastness.
When customers have high chlorine fastness requirements:
Cotton, viscose, hemp and other fabric dyeing, it is necessary to use high-chlorine fastness reactive dyes or vat dyes.
Among the moderate-temperature reactive dyes, the chlorine-resistant chlorine color of domestically produced three primary colors (yellow M-3RE, red M-3BE, blue M-2GE, or yellow A(B)-2BFN, red A(B)-2BFN, and blue A(B)-2GLN) Fastness is good, up to 3-4 (effective chlorine 50 mg/L), and all active black, active cuilan's chlorine fastness is very poor, only 1-2.
Among the commonly used vat dyes, most of the dyes have good chlorine fastness, all of which are above 3 (effective chlorine 50 mg/L). Only the lanthanone-structured dyes (Lan RSN, Blue GCDN, Blue BC, Brilliant Blue 3G, Dark Blue VB, etc.) performed poorly, only about Grade 2 (effective chlorine 50 mg/L), so they could not be used.
When reviewing orders, why do you emphasize the importance attached to the fastness of dyes? This is because other indicators in the order, such as the width and shrinkage rate, can be corrected by rearranging them if they do not meet the requirements of the merchants. However, once the color fastness is not up to standard (caused by improper dye selection), there is almost no possibility of change, and only the press warehouse or discount sales, and then re-expanding production, the economic losses are naturally huge.
1.2 Review
The standard samples provided by the merchants (also called the original samples) play two roles: one is the standard of color, and the other is the standard of touch. However, there are many other contents hidden in the standard. If they are not thoroughly understood and read, they will also be singled out.
(1) For the original sample for customer, whether it contains fluorescent whitening agent, do the identification. For this reason, it is necessary to check whether the original sample is fluorescent in a standard light box. If it is fluorescing, it must be clarified. Is this fluorescence a specific request of the merchant? This must not be arbitrarily determined, otherwise it may cause the staining of the dyeing material to be repaired. Can't even ship.
(2) To analyze the color of fabric by blending or fabricating the original sample for customer. If the sense of double color is obvious, this may be due to uneven dyeing of different fibers, but it may also be a merchant's "style" requirement. This must be clarified. It is not possible to preserve the sense of double color by painting and scooping. It is also not advisable to change it without permission. It will become a uniform color, or it will often result in rework.
(3) When the original samples provided by the merchants are "flash color fabrics" (fiber black) or "flash fabrics" (single dye fibers), it is necessary to identify the color of different fibers. Fiber is the kind of color. If the color and fiber are crowned and worn (note: the effect of the fabric is sometimes similar when the blending ratio and the organization specification are appropriate), once the merchants find that the fabric is miscolored, even if the fabric is similar, the goods will be rejected, so the dyeing can only be "Pressure storehouse." Because it is stripping and re-dyeing, it is usually due to unclear or dark shading, can not reproduce the original style.
(4) When the original sample provided in the merchant's order is a twill weave (especially a twill weave made of different fibers), the twill weave is generally used as the front face. However, there are exceptions and the negative is positive.
Therefore, when verifying the original samples of merchants, if you find that the swatches are facing up, you must make sure that they are positive and that the opposite is positive, or that the merchants will stick the swatches in reverse. Do not be empiricist and change without authorization. Otherwise, sample replay is a trivial matter. If you invest in large-scale production, you will make a big mistake, because the positive and negative colors usually have obvious differences.
The above analysis shows that only through careful "single review" and careful "proof of sample" can we fully and correctly understand the requirements of merchants on product quality, and then we can formulate the correct process plan in a targeted manner.
2 Lofting and replicating
Merchants always provide original swatches before placing orders. The company uses the original swatches as the standard sample for “palm-like†confirmation for the merchants, and the merchants will confirm the production orders after confirmation.
Before the production order is put into production, it is necessary to first enlarge the sample. The so-called “stake out†is to produce large samples according to the size of the palm. The success of lofting (that is, color and original swatches meet the requirements of merchants) can be officially put into large-scale production.
The problem here is that the sample of the palm of your hand is always ahead of schedule, and the used semi-finished products, dyes and auxiliaries are in stock. While the production of the stakeouts will always take one week or a few weeks, so it is not possible to belong to the same batch of semifinished products and dyestuffs and auxiliaries used in hand-to-hand and sample production. There is always a certain degree of difference between the two. .
These differences have significant effects on the accuracy of the sample amplification. such as:
1 For the semi-finished products used for sample and scale up, in the aspects of whiteness, gross effect, level of setting, degree of grinding, and especially the ability to absorb color (mainly the degree of mercerization), if there is a difference, the first sample must be influenced. Magnification of accuracy.
2 The dyes and auxiliaries used for the sample and magnification samples will be inaccurate if the batch is different due to the difference in quality.
This is because some dyestuff manufacturers in China are lagging behind in process technology and relatively weak in production management, resulting in the dyestuffs being synthesized. The depth and color of the dyes are unstable, which is a big difference from the factory standard. Therefore, in the commercialization process, only by external dyes can be significantly "color" (similar to the color correction in the dyeing), the purpose is to make the dye or finished product strength, color light close to or meet the factory standards.
It is worth noting that there are three major consensuses at home and abroad regarding the use of additional dyes for "color grading":
First, the additional dyes used for the color matching must have good compatibility with the main dyes in terms of dyeing properties, especially the synchronization of the dyeing, the similarity of the color fastness, and the admixture of the color matching depth. However, some manufacturers of dyes do not have strict choices for additional dyes used for coloration, and the tendency to ignore the performance of “color-grading†is rather serious, that is, the lack of good compatibility between the color dyes and the subject dyes.
Second, the amount of additional dyestuffs used for coloration is generally required to be controlled within 2% because 2% of the additional dye has less effect on the dyeing properties of the main dye. However, in some dyeing companies, the amount of extra dye used for color correction far exceeds the upper limit of 2%, even as high as 5-10%, so that after dyeing, the dye finished product has actually changed from a dye of a single structure to a mixed dye.
Because of this, for the same dye, not only the products of different manufacturers have a difference in shades and shades, but also products of different batches from the same manufacturer. The depth and color of the products are also different. In actual production, a single dye dyes the same fiber. Once the process conditions fluctuate, not only the depth will change, but also the color shade will change. The problem of the disease is here.
In addition, some dye enterprises have dried out of granulation technology, the commercialization level is not high, making the proportion of various components in the finished dyes different, in the process of transport, storage, use, resulting in the phenomenon of stratification, brewing the same dye The upper and lower layers of the packaging have different strengths and even shades.
There is no uniform standard for domestically produced additives. Many additives manufacturers' products, their concentration and even the composition of the ingredients are very random, and there is no lack of product composition with the sales price of the level of adjustment for the production of enterprises. Therefore, there will be differences in the quality of dyeing auxiliaries between batches and batches, and even barrels to barrels.
The most effective technical measure is to use the master sampler with high technical level and strong sense of responsibility before the amplification sample to use the semi-finished products, dyes and auxiliaries used in the workshop to enlarge the sample. ". Practice has proved that the “replica†of the palm sample verified by the merchant before amplification of the sample not only can effectively overcome the harm caused by the difference in the quality of dyes and auxiliaries, but also confirm the presence of the sample. Human error, such as the proofing process is inconsistent with the regulations; improper combination of dyes; incorrect application of additives; incorrect prescription data; improper proofing operations, etc., and “checking†effect.
Therefore, the sample prescriptions confirmed by the merchants cannot be regarded as the basis for the enlargement without being “repeatedâ€. Practice has proved that serious Sweater Knit Fabric Hacci,High Quality Hacci Fabric,Hacci Knitting Fabric,Hacci Knitted Fabric Shaoxing Winfar Knitting & Embroidery Co.,Ltd. , https://www.wfknitting.com