Study on the technology and thermal comfort of heating fiber warm knitted fabric

【 Key words 】 Eks fiber; heating fiber; warm fabric; knitted fabric; craft; thermal comfort performance

In response to consumer demand for fabric warmth and comfort, research and development of heating fiber warm knitted fabrics, Eks heating fiber into the fabric, so that the fabric has a good warmth and comfort, to meet the health needs of consumers.

1   Introduction of the performance of heating fiber

At present, the heating fibers on the market mainly include Eks of Toyobo Co. , Ltd., Thermolite of DuPont of the United States , Thermotron of Unitek of Japan, and Thermogear of Asahi Kasei Co., Ltd. of Japan . This product is mainly produced using Eks heating fiber. The Eks the Power added to the polyester polymer are mixed, can be spun into fibers Eks semi-permanent, since the Power Eks between chemically combined with the fibers, the fibers hydrophilic groups Eks than any natural fiber, it is not only Eks It can adjust the temperature and humidity between the human body and the clothes, and also has the function of protecting the human body and the environment.

2   Product design and main production process

2.1   product design

Eks heating fiber has high hygroscopicity, heat generation and heat insulation, and can be used for the development of thermal fabrics such as four-sided elastic and non-woven fabrics. Here only introduces the design and production of the former product. It is produced by double-sided machine, the surface is cotton, and the acrylic fiber inside is treated by pulling, so that the fabric has high resilience, dimensional stability, good fatigue resistance and resistance. The abrasion and breathability make it warmer, more comfortable and refreshing.

2.2   Weaving process

2.2.1   Device parameters

The model is Bushu double-sided circular weft machine, machine number 28 needle / 25.4mm , cylinder diameter 762 mm , the number of roads 72 F , machine speed 23 r / min , using cotton wool alignment.

2.2.2   raw material

Using combed cotton yarn 13 tex, 14.8 tex Eks yarn, 15.5 tex and 4.4 tex acrylic yarn spandex.

2.2.3   Needle arrangement

Both the dial needle and the syringe needle are arranged in the order of ab .

2.2.4   Triangle arrangement

The triangular arrangement is shown in Table 1 , three ways and one cycle.

Table 1 triangle configuration diagram

2.2.5   Yarning method

The first passage through the yarn 14.8 tex Eks, through the second passage 13 tex combed cotton spandex +4.4 tex, through the third passage acrylic yarn 15.5 tex.

2.2.6   Yarn ratio

The proportion of each yarn used in the product is calculated as shown in Table 2 .

Table 2 yarn ratio

2.2.7   Fabric parameters

The blank has a width of 145 cm , a blank surface density of 420 g / m ² , a light blank width of 155 cm , and a light blank density of 410 g / m ² .

2.2.8   Tuning points

In order to prevent the spandex yarn from slipping, the needle needle is generally woven first. The span yarn angle of the spandex yarn is not lower than the yarn mating angle of the cotton yarn, and the corresponding needle needle of the needle needle is returned to the origin when the needle is needled.

3    Test and Analysis of Thermal Comfort Performance of Knitted Warm Fabric

According to the thermal comfort performance test requirements of the warm fabric, combined with the relevant product testing standards, the breathability, warmth and moisture permeability are selected as the thermal comfort performance test and research project of the fabric. At the same time, in order to compare the thermal comfort performance, three kinds of similar thermal fabrics were selected as samples and tested together.

3.1   Sample selection

A total of 3 fabrics were selected for this experiment . The sample specifications are shown in Table 3 .

Table 3 sample specifications

3.2   Test methods and indicators

3.2.1   Breathability

The breathability of the fabric is customarily expressed by the amount of air permeability, that is, two fabrics.

Under the specified pressure difference, the unit area of ​​the fabric is passed per unit time.

Air volume in L / (m ² · s) [1] .

This experiment uses YG461 fabric medium pressure gas permeability meter. The environmental conditions are a temperature of 20 ° C and a relative humidity of 65 % . The standard used is GB / T5453-1997 ( Determination of the permeability of textile fabrics).

3.2.2   Warm performance

The amount of warmth depends on the amount of still air in the fabric. At present, its test indicators mainly include heat preservation rate, heat transfer coefficient and Crowe value.

The heat retention rate is a percentage of the difference between the amount of heat radiation when there is no sample and the amount of heat radiation when there is a sample, and the amount of heat radiation when there is no sample.

The heat transfer coefficient refers to the heat flux per unit area when the temperature difference of the surface of the textile is 1 °C .

The Crowe value means that the tester is sitting still at a room temperature of 2 l ° C, a relative humidity of 50 % or less, and a gas flow of 10 cm / s ( no wind ) , and the basal metabolism is 58.15 W / m ² . Comfortable and maintain an average body surface temperature of 33 °C, the insulation value of the clothes worn at this time is 1 Cro (CLO) value (1CLO = 0.155 m ² · ° C / W) [2] .

Test equipment: fabric insulation tester SFJJ-606PC , which is a flat fabric insulation tester controlled by a microcomputer. According to the requirements of GB / T11048-1989 (the method of textile insulation performance test method ) , the standard state ( body temperature 36 °C ) is set , and the heat preservation rate , heat transfer coefficient and the kero value h are calculated by the microcomputer by the constant temperature difference heat dissipation method .

Environmental conditions: temperature (20 ± 2) °C , relative humidity (65 ± 2) %.

Experimental parameters: preheating time 30 min , heating cycle 5 times, test plate temperature 36 °C , test plate size 250 mm × 250 mm . Each test was measured 3 times and the arithmetic mean was obtained.

The standard is the 2009 edition of the "Knitted Thermal Underwear Industry Standard".

3.2.3   Moisture permeability

Moisture permeability: Under the condition that there is a constant water vapor pressure on both sides of the fabric, the mass of water vapor passing through the fabric per unit area within a specified time is expressed in g / (m ² · d) [3] .

Environmental conditions: temperature 20 ° C , relative humidity 65 %.

Permeation chamber conditions: temperature 38 ° C , relative humidity 90 % , air flow rate 0.3 ~ 0.5 m / s .

Experimental standard: GB / T 12704-1991 "Determination of moisture permeability of fabrics".

In the test, the method A is used for moisture permeability, that is, the moisture permeable cup containing the moisture absorbent or water and sealed with the fabric sample is placed in a sealed environment of a predetermined temperature and relative humidity, according to the moisture permeable cup ( including the sample and the sample for a certain period of time). The change in mass of the moisture absorbent or water ) is calculated as the moisture permeability.

Laboratory equipment materials: experimental box, moisture permeable cup, balance, moisture absorbent, standard sieve, desiccant, measuring cylinder.

The moisture permeability of the sample is calculated as follows:

WVT= 24 × △ m / (S · t)            (1)

Where: WVT - 24 h moisture permeability, g / (m ² · d) ;

△ m —— the difference between two weighings of the same experimental combination, g ;

S —— the experimental area of ​​the sample, m ² ;

t - experimental time, h .

3.3   Test results and analysis

3.3.1   Gas permeability test data and analysis

The gas permeability test data is shown in Table 4 .

Table 4 gas permeability test results mm.s

It can be seen from Table 4 that the heat-generating fiber cotton-wool cloth has the best gas permeability, and the ordinary four- sided shell does not fall down. The explanation of this phenomenon is that the heat-generating fiber cotton-wool cloth with cotton-wool structure is thinner and has a larger air permeability. The gas permeability is better; and the difference in fabric materials makes the fabric have different gas permeability properties. It can be seen that the gas permeability of the fabric is not only related to the structure of the fabric, but also affected by the raw materials used in the fabric.

3.3.2   The thermal performance test data and the analysis of the thermal performance test data are shown in Table 5 .

       Table 5   Thermal performance test results

From Table 5, it can be concluded that the heating fiber is not the best in warmth, and the heating fiber is the second. The ordinary four-sided elastic is the worst in warmth. The thicker the fabric, the better the warmth is. The warmth of the fabric of the fiber is better than that of the ordinary fiber. It can be seen that the warmth of the fabric is not only related to the structure of the fabric, but also related to the properties of the yarn ( raw material ) of the fabric. The thicker the fabric, the better the warmth; the warmth of the heating fiber Better than ordinary fiber.

3.3.3   Moisture permeability test data and analysis

The moisture permeability test data is shown in Table 6 .

Table 6 moisture permeability test results

It can be seen from Table 6 that the heat-absorbing fiber cotton wool cloth has the best moisture permeability, the ordinary four-sided shell does not fall down, the thinner the fabric, the better the moisture permeability; the different materials, the moisture permeability is different, the ordinary four-sided bomb does not fall down The moisture permeability is good, and the moisture permeability of the fabric is not only related to the structure of the fabric, but also related to the raw materials of the fabric.

3.4   Test conclusion

Through the above test of thermal comfort performance, it can be known that the selection of fabric raw materials and the choice of structure will affect the thermal comfort performance of the fabric. The thinner the fabric, the better the breathability and moisture permeability of the fabric; the heating fiber cotton wool cloth and heat The warmth of the fiber on both sides of the velvet is better than that of the ordinary four-side bomb, which means that the warmth of the heating fiber is better than that of the ordinary fiber.

4 Conclusion

The production practice and thermal comfort performance test of Eks heating fiber thermal insulation fabric show that the fiber can be used for the production of knitted thermal fabrics, but the reasonable selection of raw materials and organizational structure must be considered when designing products, in order to better satisfy the consumers' pursuit of thinness. , warm and comfortable requirements.

references:

[1] GB / T 5453-1997. Determination of the permeability of textile fabrics [s].

[2] GB / T 11048-1989. Textile insulation performance test method / new standard [s].

[3] GB / T 12704-1991. Determination of moisture permeability of fabrics [S].

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