CN1097105C - Cut resistant yarn fabric - Google Patents

Abstract

The present invention discloses a fabric made of para-aramid yarn, wherein the yarn is of low twist and the staple fiber in the yarn has high linear density, which has increased cut resistance and maintains comfort.

Description

Cut-resistant yarns and fabrics and garments

Background of the invention

Fabrics used in cut resistant garments are generally stiff and bulky due to the understandable requirement to use high modulus, high strength yarns. In the past, cut-resistant clothing such as gloves, aprons and protective sleeves were processed from rigid yarns. The fabrics made of such yarns were hard, uncomfortable and rough to the touch. Improvements to the yarns made the resulting fabrics cut-resistant. increase, resulting in stiffer and less comfortable fabrics. This invention relates to cut resistant woven and knitted fabrics which exhibit improved cut resistance while maintaining a comparable or softer hand.

Summary of the invention

The present invention relates to garments with improved cut resistance made from yarns having a linear density of 150 to 5900 dtex (133 to 5315 denier) and a twist factor of less than 26, wherein the yarn contains a yarn having a linear density of 3 to 6 dtex ( 3.7 to 5.4 denier para-aramid staple fibers with a length of 2.5 to 15.2 cm (1 to 6 inches).

The present invention also relates to yarns and cut-resistant fabrics made from yarns having a weight of 135 to 1017 grams per square meter (4 to 30 oz/ ^yd2 ). Detailed description

There has long been a tension in the field of protective clothing between comfort and effectiveness; and great efforts have been made to increase its effectiveness while maintaining comfort. The present invention represents such an improvement in the field of cut resistant garments and fabrics. With the present invention it is possible to increase the effectiveness of cut resistance while maintaining the comfort of fabrics and protective clothing such as cut resistant gloves.

It has been found that protective garments made from yarns spun from para-aramid fibers are softer if the yarns have less twist. Furthermore, it has been found that the cut resistance of the fabric of such garments is independent of the degree of twist of the yarns in the fabric, but that the cut resistance of the fabric improves with the increase of the linear density of the monofilaments used in the yarn.

Para-type aramid fiber means that the fiber is made of para-aramid polymer; and polyparaphenylene terephthalamide (PPD-T) is the best para-type Aramid polymer. PPD-T means a homopolymer obtained by molar-to-molecular polymerization of p-phenylenediamine and terephthaloyl chloride, or a combination of p-phenylenediamine combined with a small amount of other diamines and a small amount of other diacid chlorides Copolymers obtained from terephthaloyl chloride. Generally, up to about 10 mole percent of p-phenylenediamine or terephthaloyl chloride, or slightly higher, other diamines and other diacid chlorides are also usable as long as the other diamines and other diacid chlorides have no reactive groups with which interfere with the polymerization reaction. PPD-T also means a combination of other aromatic diamines and other aromatic diacid chlorides, such as 2,6-naphthaloyl chloride or copolymers of chlorine or dichloroterephthaloyl dichloride, as long as other aromatic Acid chlorides are not quantitatively counterproductive to the properties of the para-aramid.

Additives can also be used in para-aramid fibers, and it is known that up to 10% by weight of other polymeric materials can be mixed with aramid, or aromatic polyamides can be substituted with up to 10% by weight of other diamines. Diamines in aromatic polyamides or copolymers in which up to 10% of other diacid chlorides replace the diacid chlorides in aramids.

Staple fibers for spinning yarn generally have a specific length and a specific linear density. The fibers used in the present invention may be of any length suitable for spinning yarn processing. Staple fibers can be used in lengths of 2.5 to 15.2 cm (1 to 6 inches) and preferably are 3.8 to 11.4 cm (1.5 to 4.5 inches). Yarns made with staple lengths less than 2.5 cm have been known to require high twist to maintain processing strength; yarns made with staple lengths greater than 15.2 cm are more difficult to manufacture because the longer staple lengths Can cause mutual entanglement and breakage to get very short fibers. The staple fibers used in the present invention are generally obtained by cutting continuous filaments into certain predetermined lengths; but the staple fibers can also be made by other methods such as stretch cutting; and the yarn can also be made of such fibers and multiple or different Made with distributed short fiber lengths.

Spun yarns are held together by twisting the yarns as they are spun. The crimped short fiber is spun on a spinning machine to form a yarn with a certain twist, and the twist makes the fibers entangled with each other to form a yarn. In the past, cut-resistant fabrics for protective clothing used high-twisted yarns for practical applications. It is generally believed that high-strength yarn requires high twist; and good cut resistance requires high strength. The high twist causes the fibers to be tightly entangled in the formed yarn resulting in a rather stiff yarn.

It has now been found that high twist yarns are not required for effective protection; and in fact it is known that cut resistance is independent of the twist of the yarns used to make the protection fabric. However, twist is an important factor to the softness or comfort of such fabrics. It has been found that fabrics made with low twist yarns are much softer and have a much better "hand" than fabrics made with high twist yarns. In addition, reducing twist is known to increase the softness of a fabric regardless of the type of yarn it is used in or the material it is made of.

Yarn twist is generally expressed by a coefficient called "twist coefficient", which can also be called twist factor. A higher twist factor indicates a greater amount of twist. Until now, cut-resistant fabrics for protective clothing have preferably been made from yarns with a twist coefficient greater than 28 (tex) ^1/2 (twists/cm) and staple fibers with a linear density less than or equal to 2.5 dtex. The twist factor (TF) of a yarn is an indication of the degree of twisting of the fibers in the yarn, which can be determined in any of several dimensional systems, taking into account the linear density of the yarn:

number system

TF＝(twist/cm)(number) ^1/2

British branch number system

TF＝(twist/inch)/(cotton yarn count) ^1/2

Metric branch number system

TF＝(twist/meter)/(common count of yarn) ^1/2

The "imperial cotton yarn count" of a yarn is the skein count of a yarn weighing 454 grams (1 lb) and 768 meters (840 yards) long.

The "common count" of a yarn is the number of kilometers per kilogram of yarn.

For the purpose of this article, the number twist coefficient is the SI unit of number ^1/2 twist/cm.

Yarns with a twist coefficient of less than about 26 in the fabrics of the present invention are known to result in soft fabrics which can be made into comfortable yet cut-resistant gloves. There needs to be some twist in the yarn in order for the yarn to hold together, and tests have shown that cut resistance is not affected by changes in yarn twist. That is, adding additional strength to the yarn with increased twist does not in turn increase cut resistance. It has been concluded that practice has shown that the yarns of the present invention should have a twist multiplier of at least about 10. For a single 10-inch (equal to 590 dtex) yarn, the twist coefficient is about 10 converted into a twist of about 1.3 twists per centimeter. The yarns of the present invention preferably have a twist multiplier of 15 to 22.

Yarn is made from staple fibers. It is known that the yarns used in the practice of the invention should have a yarn density of 150 to 5900 dtex, preferably 550 to 4700 dtex. Yarns may be single or several plied and may or may not be twisted together.

With regard to the linear density of individual fibers, it has been found that increasing the linear density of staple fibers increases the cut resistance of the yarn. In the past, cut resistant protective clothing yarns have used individual staple fibers of about 2.5 dtex or less. While such yarns are suitable for many applications, it is known that the cut resistance of fabrics increases as the linear density of the staple fibers used in the yarn increases. Furthermore, the comfort of such a fabric is known to be maintained as the twist of the yarns used for it is reduced. Thus, application of the present invention makes it possible to produce fabrics having cut resistance and improved comfort comparable to known products. For example, fabrics with improved cut resistance can be made from yarns having a twist modulus of less than 26 and containing para-aramid staple fibers having a linear density of 3 to 6 dtex. Such fabrics would have increased cut resistance due to increased fiber linear density and maintained comfort due to reduced yarn twist.

From a comfort point of view, it has been found that the low twist yarns of the present invention should be made from staple fibers having a linear density of 3 to 6 dtex and preferably 4 to 5 dtex. Fibers of less than about 3 dtex may not yield the improved cut resistance of the present invention. Fibers greater than about 6 dtex exhibit good cut resistance, but are not aesthetically pleasing and do not result in fabrics of suitable comfort.

The yarns of the present invention may be produced by any suitable spinning method, for example, cotton/worsted/woolen ring spun yarns and open end spun yarns.

The yarns spun according to the present invention have low twist and high linear density, which can be made into knitted or woven or even unidirectionally laid fabrics with high cut resistance. Moreover, the spun yarns can also be made into gloves and other garments directly from looms. Cut resistance is a function of the linear density of the filaments in the yarn rather than the way the yarn is presented in the fabric. Determination method Cut resistance, the method adopted is "Standard Determination Method for Measuring Cut Resistance of Protective Clothing Fabrics", recommended as ASTM standard (ASTM Subcommittee F23.20). To perform the measurement, a knife edge is pulled once under a specified force across the sample attached to the mandrel. At several different forces, record the pull-through distance from initial contact to cut-through and construct a graph of force versus cut-through distance. The force at a cut-through distance of 25 mm was determined from the graph and taken as a basis for the consistency of the knife supplied. Record the measured force as the resistance to cutting.

The blade is a stainless steel blade with a sharp edge of 70mm long. At the beginning and end of the assay, the supplied blade is calibrated with a 400 g load on the neoprene calibration material. Use a new blade for each cut measurement.

The sample is a 50 x 100 mm rectangular fabric section cut with the warp and weft directions at 45°.

The mandrel is a round conductive rod with a radius of 38 mm to which the sample is attached with double-sided tape. The blade is drawn across the fabric on the mandrel at right angles to the longitudinal axis of the mandrel. A cut through is recorded when the blade makes electrical contact with the mandrel.

example Knitted gloves and fabrics to be measured

Para-aramid filament yarns of four different linear densities were crimped and cut into staple fibers for spinning into test yarns for these examples. The filament yarn is poly-p-phenylene terephthalamide yarn, sold under the trademark Kevlar® 29 by E.I. du Pont de Nemours and Company, which is made of linear densities of 1.67, 2.50, 4.67 and 6.67 Made of dtex filament. The length of the short fibers was 11.4 cm.

A portion of each staple fiber is spun by worsted spinning equipment into yarns of different twists. The double-ply yarn is spun into a linear density of 590dtex (English branch 20/2), and the twist coefficient is shown in Table 1 and Table 2.

Sample gloves and sample fabrics were knitted with these yarns on a Shima Seiki glove knitting machine, starting with 4 and 6 needles. The average weight of knitted fabric and coarse yarn knit gloves from 4 starts was 478 g/ ^m2 (14.1 oz/ ^yd2 ); and the average weight of knitted fabric and gloves from 6 starts was 783 g/ ^m2 (23.1 oz/ ^yd2 ). example 1

The above-prepared gloves were used for the cut resistance test to obtain the relationship between the cut resistance and the fabric parameters such as staple fiber linear density and yarn twist coefficient. The results of those measurements are listed in Tables 1 and 2 below, for 6 and 4 fabrics, respectively.

Table 1 (6 fabrics) linear density 1.67dtex 2.50dtex 4.67dtex 6.67dtex twist cut resistance (kg-force) 14 1.4 1.6 1.8 -17 1.3 1.6 1.7 1.819 1.4 1.5 1.6 1.822 1.3 1.4 1.3 1.7924 1.3 1.4 1.3 1.7924 1.5 1 1.4 1.8 1.829 1.4 1.5 1.9 2.031 1.3 1.4 1.7 1.8 Average 1.3 1.5 1.8 1.9

Table 2 (4 fabrics) linear density 1.67dtex 2.5dtex 4.67dtex 6.67dtex twist cut resistance (kg-force) 14 1.0 1.1 1.2 -17 1.0 1.1 1.5 1.6

19 1.1 1.2 1.4 1.5

22 1.1 1.2 1.4 1.5

24 0.9 1.2 1.4 1.6

26 1.0 1.0 1.6 1.5

29 1.0 1.2 1.5 1.6

31 1.2 1.1 1.4 1.5

Average 1.0 1.1 1.4 1.5

The cut resistance data obtained from this example show that cut resistance is a definite function of staple fiber linear density and is relatively independent of twist. The cut resistance improves significantly with the increase of staple fiber linear density, and the improvement is most significant when the staple fiber linear density is greater than 2.5 dtex. Example 2

The 6 fabrics prepared above were used for comfort measurement, wherein 31 fabric samples were used to determine the "hand feeling" of each sample by touch. Each sample was felt by 10 people and rated for softness on a scale of 1-5 (1 being the hardest and 5 being the softest). The overall ratings of the 10 individuals were averaged and recorded in Table 3 below.

Table 3 Linear density 1.67dtex 2.50dtex 4.67dtex 6.67dtex twist comfort evaluation (average of 10 people)

14 4.4 4.4 3.2 -

17 4.2 4.4 3.1 2.9

19 4.2 4.0 3.0 2.5

22 3.6 3.5 2.5 2.1

24 3.5 3.5 2.2 2.5

26 3.3 3.2 2.0 1.3

29 3.0 2.4 2.0 1.8

31 2.8 2.0 1.4 1.4

From the comfort data for this example, it can be seen that comfort is a direct function of yarn twist. Comfort improves significantly when twist is reduced. As previously stated, commercially available gloves are typically made from staple fibers having a linear density of less than about 2.5 dtex and yarns preferably having a twist multiplier of greater than 28. It can be seen from Table 3 that the comfort rating of such fabrics is 2 to 3 in these measurements; rated as good. With the reduction of staple fiber linear density and the reduction of twist, the comfort is obviously increased.

Examples 1 and 2 show that fabrics made from yarns with a staple linear density greater than 2.5 dtex exhibit improved cut resistance while fabrics made from yarns with a staple linear density of less than 6.67 dtex and a twist modulus of less than 26 exhibit improved comfort. The combination of those results shows that a yarn with a staple linear density of 3 to 6 dtex and a twist coefficient of less than 26 will make the fabric both cut resistant and comfortable.

Claims (17)

1. A cut-resistant yarn having a linear density of 150 to 5900 dtex and a twist coefficient of less than 26, characterized in that the yarn comprises para-type aramid staple fibers having a linear density of 3 to 6 dtex and a length of 2.5 to 15.2 cm . 2. Yarn according to claim 1, characterized in that the staple fibers have a linear density of 4 to 5 dtex. 3. Yarn according to claim 1, characterized in that the yarn has a twist multiplier of 15 to 22. 4. Yarn according to claim 2, characterized in that the yarn has a twist multiplier of 15 to 22. 5. A cut-resistant fabric made of cut-resistant yarns having a linear density of 150 to 5900 dtex and a twist coefficient of less than 26, characterized in that the yarns comprise a linear density of 3 to 6 dtex and a length of 2.5 to 15.2 centimeters of para-aramid staple fiber, and the weight of the fabric is 135 to 1017 grams per square meter. 6. Cut resistant fabric according to claim 5, characterized in that the staple fibers have a linear density of 4 to 5 dtex. 7. Cut resistant fabric according to claim 5, characterized in that the yarns have a twist multiplier of 15 to 22. 8. Cut resistant fabric according to claim 6, characterized in that the yarns have a twist multiplier of 15 to 22. 9. Cut resistant fabric according to any one of claims 5-8, characterized in that said fabric is formed from said yarns by weaving. 10. Cut resistant fabric according to any one of claims 5-8, characterized in that said fabric is formed from said yarns by knitting. 11. A cut-resistant garment, characterized in that it is made of the cut-resistant fabric according to any one of claims 5-8. 12. A cut-resistant garment, characterized in that it is made of a cut-resistant fabric according to claim 9. 13. A cut-resistant garment, characterized in that it is made of a cut-resistant fabric according to claim 10. 14. A cut resistant garment according to claim 11 in the form of a glove. 15. A cut resistant garment according to claim 12 in the form of a glove. 16. A cut resistant garment according to claim 13 in the form of a glove. 17. A cut-resistant garment, characterized in that it is made of the cut-resistant yarn according to claim 1. .