How to Improve the Quality of Lace Fabric and Lace Trim: Improvement In Dyeing and Finishing Process

Quick Takeaways

By improving the dyeing and finishing process for lace fabrics will improve the color brightness of lace fabrics, lace trim, increase the stability of lace pattern spacing and pattern width, ensure the fullness of the pattern, and improve the quality and grade of lace fabrics or lace trim.

 

A bit more about lace fabric material

Lace fabric refers to the product formed by using elastic yarns on a multi-comb or Jacquard Raschel warp knitting machine, also known as Raschel fabric and Jacquard fabric. Generally, chemical fiber raw materials such as nylon, polyester, spandex, viscose, natural fiber raw materials and gold and silver are woven into a whole floor pattern, which is called a whole piece of lace fabric; or a lace strip fabric, which is called lace trim. If spandex is added to the fabric, it is also called stretch lace trim or stretch lace fabric, or simply stretch lace. If no spandex is added, it is called non-elastic lace or non-stretch lace fabric.

 

In the past, Lace fabrics used only as accessories to decorate garment, mainly used for underwear shoulder straps, bra cups, waist seal front, trousers triangle area, hem and trouser edges. In the 1980s, lace fabrics began to appear frequently in social dresses, bridal dresses, movie stars and model dresses. Coupled with the gradual popularity of various sexy underwear, body shaping underwear, body underwear, transparent and see-through clothing in recent years, lace fabrics have played a large role in the fashion industry. At the same time, the use of lace fabrics has expanded from clothing decoration to home decoration and accessories, and the demand is increasing rapidly.

 

Problems of general lace fabric dying and finishing process and the solution

 

Ordinary lace fabric processing technology is relatively simple, that is, directly into the dyeing vat for dyeing, and then finishing and shaping. The color of the lace fabric product produced in this way is dim, and the flower pattern pitch and flower pattern width are also retracted greatly, which limits the wider usage of the finished lace fabric. The novel dyeing and finishing process of lace fabric mentioned in this article has added two pretreatment processes: degreasing and pre-shaping. The color vividness of the finished lace fabric has been significantly improved, and the flower patter pitch and flower pattern width of the lace fabric are stable without shrinkage. The shape is fuller and more three-dimensional. As a result, the grade level of the products is improved, which is essential for the lace fabric factory or dealers to win new customers and orders.

 

Solution: Lace fabric pretreatment process

 

Lace fabric degreasing process

There are two main methods of degreasing for lace fabrics: degreasing in the dyeing tank or degreasing in the flat degreasing washing machine. When degreasing in the dyeing tank, problems are extra procedures, meaning long time, complicated process and high cost. While, when degreasing in the flat degreasing water washing machine, the production efficiency is higher and at the same time, the amount of additives is reduced, and water and energy are saved.

 

Machines and process for lace fabric desgreasing

Machines：

Flat degreasing water washing machine with 8 work stations.

 

Processing speed:

For extra white, tooth white, light medium color lace fabrics, the recommended speed is 20 m/min; For dark color lace fabrics, the speed is 25 m/min, much faster.

 

Desgreasing process:

Lace Fabric Relaxation -> Soaking in Tank (Temp. 50 ℃) -> First Degreasing （Temp. 50 ℃）-> Second Degreasing with Vibration (Temp. 95 ℃) -> Third Degreasing Vibration (Temp. 95 ℃) -> First Water Washing (Temp. 85 ℃) -> Second Water Washing (Temp. 75 ℃) -> Acid Neutralization Washing (Temp. 60 ℃) -> Third Water Washing (Temp. 40 ℃) – Processed Fabric Collection.

 

For degreasing formula used in the process, listed in Table 1 and Table 2

 

Which Tank	Degreasers/g∙L-1	soda ash/g∙L-1	Chelating agent /g∙L-1	Glacial acetic acid /g∙L-1
Soaking Tank	3.0	1.5	1.0	0
Degreasing Tank	2.6	1.2	0.6	0
Acid Tank	0	0	0	0.3

Table 1 Major Degreasing Liqui Formula

 

Liquid Type	Degreasers/g∙L-1	soda ash/g∙L-1	Chelating agent /g∙L-1	Glacial acetic acid /g∙L-1
Degreasing Liquid	8.0	4.0	1.2	0
Acid Liquid	0	0	0	2.0

Table Supplementary Liquid Formula

 

Important tips for better degreasing result

 

The degreasing fluid is added evenly in each degreasing tank according to the processing lace fabric volume, and the acid washing fluid is replenished in the acid washing tank; in addition to a large mesh drum with a diameter of 1 200 mm, the degreasing  vabration tank has two built-in oscillations with a diameter of 800 mm. The drum, powerfully hits the water, greatly improves the penetration of the degreasing liquid to the fabric, and the water temperature is more uniform due to the stirring of the degreasing liquid, which improves the washing efficiency.

 

Takeaways for better degreasing process:

 

• There are many types of lace fabrics, and the patterns of lace fabric or lace trim are ever-changing. Every new lace pattern designed by the weaving factory needs an unique ID. In order to prevent the various lace patterns from being confused during the production process, It is best to cut a 10.0 cm square cloth sample from the lace cloth beginning part and nail it to the upper corner of the engineering work card to distinguish other lace patterns and find problems easily;

 

• The weaving equipment that produces lace fabrics or lace trims might cause broken yarns, missing needles, and holes in the grey fabric due tomachine failures, and may even leave broken needles on the loom. Therefore, the fabric relaxation process and initial fabric inspection work is very important, and the surface quality of the incoming lace fabric blanks should be carefully checked. Pick out the fabric defects and stitch them in time to prevent the fabric guide roller from being broken, cracked or crushed during the degreasing water washing process;

 

• After relaxing the lace grey cloth, the seam strength of the grey cloth is very important, because the bottom net of the fabric structure mostly adopts hexagonal opposing mesh (net-like bottom cloth, transparent and thin), which is easy to cause loosening or cracking when stretched by external force. Therefore, it is best to use a three-thread overlock sewing machine when sewing the head, and the two cloth heads are stitched with a 5.0 cm wide cloth strip to avoid the influence of artificial stretching and machine during the production process, and if a seam slippage testeris available, it will give you much more confidence to validate;

 

• Pay attention to check and remove thread ends, knots, and metal burrs on the surface of the machine through which the cloth guide roller of the flatdegreasing water washing machine and the grey cloth pass, to prevent the grey cloth from entanglement, resulting in hooking or pilling.

 

Lace Fabric Pre-shaping Process

 

At present, most of the popular lace fabrics in the market are elastic lace and monolithic lace fabrics. The content of spandex added is generally about 10%. Commonly used raw materials are nylon filament, nylon high-elasticity shiny and matte yarns, which make the fabric highly elastic and increase the comfort of wearing. Lace fabrics highlight the organizational structure based on a variety of different lace patterns, especially the multi-comb Raschel and Jacarrasher warp knitting fabrics woven by the press board have a floating yarn effect, and the lace patterns increase It has a three-dimensional effect with uneven layers. Therefore, the dyeing and finishing process should try to ensure the integrity and aesthetics of the product. In order to prevent the retraction and change of the lace pattern, the pre-form should not only pay attention to controlling the parameters of the lace pattern spacing given by the customer, but also stabilize the width of the lace or the width of the whole lace fabric at Allowable range.

 

 

Lace fabric pre-sahping details

 

Judging from the effect of pre-shaping, the pre-shaping temperature of most fabrics will be higher and the speed needs to be slower. The purpose is to ensure the stability of the lace fabric size, eliminate and prevent possible creases in the dyeing tank, and also for the purpose of dyeing. The final product setting is only a drying process to prevent the dye from sublimating or discoloring due to excessively high setting temperature. The same is true for the determination of the pre-shaped temperature of lace fabric.

 

For lace trim and lace fabrics mainly made of nylon, the suggested pre-forming temperature is 195 ℃.

 

Equipment: Fabric Stretching and Shaping Machine, Resin setting machine.

The process parameters:

• Temperature:195 ℃
• Processing speed:25 m/min
• The allowable range of flower pattern spacing for the whole piece of lace and lace fabric:+0.5 cm
• Allowable range of lace strip width: +0.5 cm
• Allowable width of the whole lace fabric ＋0 cm

 

Tips for getting better pre-shaping results

 

To ensure the quality of the lace fabric after the pre-shaping process, here are some important tips:

 

1. The operator should carefully check the operation card, whether the parameters provided by the customer are consistent with the predetermined shape of the gray fabri;
2. The operator of the cloth splicing head should use the overlock sewing machine to sew the 3 to 5 yards of guide cloth to facilitate the front machine operator to adjust the machine rangeflexibly and prevent the gray cloth from being teared apart when being pulled by the machine;
3. The degreased grey fabric should be pre-shaped in time during the same shift working hours to avoidpartial discoloration or defects caused by long pending time;
4. When the grey cloth is put on the machine, the starting speed of the machine should be slow. The operator of the front machine immediately uses a ruler to measure whether the spacing, strip width of the predetermined lace or the width of the whole lace fabric is controlled within the allowable range and adjusted in time according to the changes;
5. The processing speed can only be adjusted to the technological requirements when the flowerpattern pitch, strip width or width is stable within the specified range. In normal operation, it should be checked frequently to prevent deviation;
6. After the finishedfabric product is into the fabric collection container, the operator of the rear machine should measure the pattern distance, strip width, and width in time. When the deviation is not acceptable, immediately adjust the machine range or speed until it reaches the required to ensure that the parameters of the front and back products are consistent.

 

Dyeing Process Improvement

 

Dyeing machine:

High temperature and high pressure jet cylinder, normal temperature and pressure overflow dyeing machine, high temperature and high pressure overflow dyeing machine.

 

Production practice has proved that the normal temperature and pressure overflow dyeing machine has the best effect, because the nozzle overflow has less impact on the fabric during the operation of the machine, which can reduce the impact of water on the fabric and reduce the fluffing phenomenon; in addition, there is no pressure in the cylinder , It can reduce the entanglement phenomenon, and it is convenient to color matching of the cut sample.

 

Lace fabric dyeing process:

Protecting the lace fabric pattern (hiding the pattern inside)->Dyeing->Water Washing -> Soap Washing -> Color Fixing-> Water Washing -> Dehydration

 

Protecting the lace fabric patter

For the stretch lace trims and lace fabrics produced by method called pressure yarn board, the lace pattern is concave and convex due to the floating yarn effect. During the production process, especially the foreign objects or burrs in the dyeing tank, it is easy to cause scratches and fluffing. If the protruding part of the lace pattern of the whole lace fabric is nailed inside, the above phenomenon can be avoided, and it can also prevent dyeing defects such as color stains, color spots, and auxiliary spots.

 

Dyeing process

 

Lace fabric types and construction

 

Currently, lace fabrics are roughly interwoven with the following materials to form lace trim or lace fabrics: spandex + nylon (single color), spandex + nylon + viscose (two colors), spandex + nylon + viscose + gold or silver silk ( Multicolor).

 

Dyeing process details

 

The dyeing process should select different dyes for different lace fabrics. For nylon lace trim and lace fabrics, due to the high content of spandex in the tissue, in addition to dyeing nylon with acid dyes, a small amount of disperse dyes can also be added to prevent exposure and affect the overall dyeing effect; For two-color lace fabric, lace trim, first dyeing nylon and then viscose is a must.

After dyeing, pay attention to the operation and control of water washing, soaping and fixing process.

 

 

Final Lace Fabric Shaping Process

 

Since the pre-shape process has stabilized the flower pattern pitch, strip width and width within the specified range, the final shape is only to improve the flatness of the fabric surface after dyeing. Therefore, the selection of the final shape temperature is lower than the predetermined shape, the process speed can be much faster, while, the allowable range of flower spacing and strip width is more stringent.

 

 

Equipment: Same as pre-shaped equipment.

The process parameters are as follows:

Temperature: 190 ℃

Process speed: 30 m/min

Allowable range of flower pattern spacing for lace trim and lace fabric: + 0.3 cm

Allowable width of the whole lace fabric: +5.0 cm

The process operation requirements refer to the pre-shaped process requirements.

 

Conclusion

 

By improving the dyeing and finishing technology of lace fabrics, adding degreasing pre-treatment and pre-shaping process, lace fabric manufacturers can produce higher quality lace products featuring in: better color vividness, better stability of flower pattern spacing and flower pattern width, and the fullness of lace patterns is ensured.

 

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