DE3005747A1 - WOVEN FIBER FABRIC AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

Nonwoven pulp and process for its manufacture

The invention relates to a strong, durable non-woven fiber material and a method for its production.

Nonwoven fabrics have been well known for some time. They are made from synthetic fibers such as polyester and polypropylene, manufactured. In general, these fibrous materials are produced by forming a fiber layer and on this layer applies an adhesive to between the fibers create a bond and add strength to the product. In some cases (e.g. in the spunbond technique) synthetic polymers are extruded into threads and these are deformed directly into layers, whereby the threads bind each other. In other cases the fiber layer is rearranged by a liquid, after which, with the formation of usable cohesive, a resin binder is added to non-woven fiber layers (cf. e.g. US Patents 2,862,251, 3,033,721, 3 193 ^ 36, 3 769 659 and 3 081 515 and 3 025 585). Again Other nonwoven fabrics are made by forming a layer of synthetic fibers and using them High pressure jets are treated in order to felt the fibers and to create a solid structure that does not contain any binding agents needs to be self-supporting and usable for many purposes. Such techniques are in U.S. Patents 3 ^ 85 7O6 and the CA-PS 791 925 described. With the known non-woven However, fiber fabrics made from polyester fibers have the following problems: Layers of textiles bonded with adhesives Polyester fibers require a relatively large amount of binder to provide a pulp of adequate strength. This large amount of binder increases costs and can reduce the

030035/0787

desired textile-like properties of the fibers themselves affect. The types of spunbonded products are expensive and, since they are made of continuous filaments, in their functions and their textile nature is also subject to certain restrictions. For example, spunbond fabrics can be stiff and cardboard-like in products with a larger basis weight be. The highly entangled fabrics of US Pat. No. 3 ^ 85,706 have excellent fiber properties, but this known method requires considerable capital investments and large amounts of energy.

The object of the invention is therefore to solve the problems outlined above by creating a relatively economical Process for the production of strong, permanent non-woven fibers with reduced binder content.

Another object of the invention is to provide a method for producing such fibrous materials from polyester and / or polyolefin fibers.

The invention relates to solid, permanent, non-woven fibers, consisting of a layer of polyester and / or polyolefin fibers in a regularly repeating manner Patterns of weakly matted fiber areas with a higher surface density than the average surface density of the Layer are arranged, and connecting fibers that run between these areas and are matted in them, as well from a binder distributed in this layer. These fibers are produced by a process in which a layer of polyester and / or polyolefin fibers weak is matted, after which an adhesive is applied to the weakly matted layer. The pulp also contains one effective amount, for example about 2.5 to about 30 wt .- $, of an adhesive, based on fiber plus adhesive. The glue can be interrupted in the pulp in spaced apart Patterns of binding agent sites or be distributed uniformly over the entire fiber material.

03QQ3S / 0787

The nonwoven fiber fabric according to the invention is produced by forming a layer of overlapping, intersecting polyester and / or polyolefin fibers. The fiber layer is supported by a support member having a hole pattern. Streams of liquid are directed against the layer, in order to matt the layer randomly and weakly in a pattern of high-density areas, which are caused by fibers that are between these areas run, are connected. An adhesive is then applied to the layer of lightly entangled fibers.

The fiber layer can be formed in any known manner, such as by air layering or carding. The layer is then weakly felted by the fiber layer is guided under largely columnar jets of liquid, while the layer is supported by a portion having a hole pattern. An apparatus for performing such The method is described in US Pat. No. 3,885,706. An important The feature of the invention is that the fiber layer is weakly felted. For example, it is appropriate that the weak felted fiber layer has a structural dimension of the fiber felting of less than 0.1 (the test method for measuring the The structural dimension of the fiber entanglement is explained below ).

A typical device for carrying out the method according to the invention includes fieihen openings through which the Liquid (usually water) is directed under pressure in the form of columnar jets. A suitable device has up to 20 to 25 rows of openings, the openings being spaced such that about 12 to 20 openings per running cm come. The openings are preferably circular with diameters of 0.127 mm to 0.19 mm. The migratory fiber layer can run about 2.5 to 5 cm below the openings.

Using the typical devices described above representative conditions are a fluid pressure

030035/0787

from about } k to k9 bar and a fiber layer speed of up to 91 »^ m / min with a fiber weight of about 17 to 85 g / m. Routine experiments, which are well within the capabilities of an average skilled person, are completely sufficient to determine the conditions required in the individual cases.

After the fiber layer has been weakly felted, it is connected by known methods. For example, the weakly matted layer are passed through an imprinting device consisting of a pair of counter-rotating rollers. The upper (support roller) is adjustable, while in the lower (application roller) a predetermined one is to be printed Pattern is engraved. The lower roller is partially immersed in a bath of the binder solution or suspension. If If the roller rotates, it accepts binding agent, with a doctor blade wiping the binding agent off the roller with the exception of the binding agent in the engraved pattern. When the layer is passed through the gap between the rollers the binder from the engraved pattern is printed onto the layer. This is a good practice known from US patents 2,705,498, 2,705,687, 2 705 688, 2 880 111 and 3 OO9 822. If necessary, the Layer can also be glued with adhesive through complete saturation.

The adhesive used can be an aqueous latex binder, as is commonly used for non-woven fibers. Such binders are acrylic polymers, ethylene-vinyl acetate copolymers, SBR latex rubbers and the like.

After the binder has been applied, the printed Layer dried in a conventional manner, such as by passing it over a series of drying cylinders.

030035/078

The binding agent is used in an effective amount, i.e. in an amount that makes a fiber material with sufficient Leads to strength and cohesion for the intended end use. The exact amount of binder to be used depends in part on factors such as the nature of the fibers, the weight of the fiber layer, the nature of the binder, and the like. Usually the effective amount will be within a range of about 5 to about 30 weight percent based on the weight of Fibers plus binders ..

The fibers to be used in the method according to the invention are those made of polyester or polyolefin, such as polypropylene or high density polyethylene. The fibers can have a titre of 1 or less up to 15 or more, and they can now be in the form of short fibers up to 6.35 in length long, i.e. continuous threads. Fibers with a length in the range from 19 mm to 5 cm are preferably used. The weight of the fiber layer used to produce fibrous materials according to the invention can be between 0.7 g / m 2 and up to

2
vary several grams per m.

The invention is explained in detail below with the aid of examples.

example 1

A layer of polyester fibers having a denier of 1.75 and a length of 38 mm and weighing 37.9 g / m 2 was prepared by means of an air stratification device ("Rando-Webber", Rando Machine Corp., Rochester, New York). The layer is placed on a woven tape which is woven from 86 warp threads and 9h weft threads per 10 cm. It has 82 openings per cm. The layer and the tape are passed under 16 tubes. Each tube contains, in the direction transverse to the layer, 2 rows of 7 openings per 10 linear cm. Water is directed at the layer through the openings at a pressure of 17.5 bar in order to form the fibers into a pattern of high-density areas

030035/0787

weakly matted. The lightly matted layer is fed through a pair of impression rollers. The top roller is a flannel-covered rubber roller, and the lower one is engraved. The engraved roller is engraved with 2k wavy lines per 10 running cm parallel to the roller axis (see FIG. 1 of US Pat. No. 3,009,822). Each line is approximately 0.6 mm wide. The roller rotates in a pan containing binder, picks up binder and transfers it to the layer. The binder has the following composition: a self-crosslinking vinyl-acrylic terpolymer (National Starch Company, NS2853) f water and a water-soluble, hydrophilic, surface-active agent (Atlas Chemicals, Tween 20). About 8.8 g / m 2 of binder are applied. The fiber material is dried for 1 minute at a temperature of 132 ° C. in order to remove excess water and to cure the binder. The fiber material contains weakly felted fiber areas of higher density. These are connected to each other by fibers that run between the areas. The binder material runs across the fiber layer and binds the fibers together. The strength of the obtained fiber material is tested with an Instron Tensile Tester according to ASTM D-1117. The pulp has a machine direction tape strength of 1.9 lbs./in./100 grains and a cross direction tape strength of 0.89 lbs./in./100 grains.

Comparison example 1

For comparison, a part of the air-layered polyester fiber layer, as used in Example 1, not weakly matted. Rather, the binder was among the in Example 1 illustrated conditions directly on the air stratified Layer applied and cured. Another part of the air-layered polyester fiber layer was weakly felted as in Example 1 and then dried for dewatering without applying a binder. Both comparative samples were tested for strength like the sample of Example 1. Just that bindered unfelted product had a machine direction tape strength of 0.505 lbs./in./i00 gr.,

€ 3003 6/078?

and a cross direction tape strength of 0.209 lbs./in./ 100 grains. The fiber material, which was slightly felted but not provided with binding agent, had a band strength in the machine direction of 0.476 lbs./in./100 grains and a cross direction tape strength of 0.358 lbs./in./ 100 grains.

Example 2

According to the procedures described in Example 1 and Comparative Example 1, polypropylene fibers were prepared using a
"Rando-Webbers" processed into one layer. This was then weakly felted and connected by printing (with NS2853) (sample 1), weakly felted (sample 2) or connected by printing with NS2853 (sample 3). The obtained nonwoven
Fibers were tested for gripping tensile strength and specific gripping tensile strength (according to ASTM D-1117) in the machine and cross directions according to ASTM D-1117. The results compiled in Table 1 were obtained:

Table 1

Sample no. weight
(g / n. ² ) Gripping
speed tensile strength
(kg / cm) lg MR QR 1 ί * 2.2 1.98 1, 55 2 30.54 0.1 O, 09 3 41.56 0.46 O, 28

Specific

Greifzugfestig- "

ability (lbs./in/gr./yd) MR

1.86 0.15 0.44

C £ R

1.46 0.12 0.27

Comparative example 2

In the manner described in Example 1 and Comparative Example 1, rayon fibers were made into one by means of a "Rando-Webber" Layer deformed and then slightly matted and connected by printing (sample 1), only slightly matted (sample 2) or connected only by printing (sample 3). The received

Ö3003B / 0787

nonwoven fiber layers were tested for tape strength in Machine and cross direction tested to ASTM D-1117. The results shown in Table 2 were obtained obtain:

Table 2

Sample No. Weight of tape strength " (g / m) (lbs./in./100 grains / yd)

MR QR

1 ^ 9.27 0.9 ^ 0.53

2 36.3 * 4 x 0.84 0.51

3 ^ 7.79 1.03 0.67

Unlike in the case of polyester and polypropylene fibers, if rayon fibers are weakly matted and also through Printing are connected, the strengths are not greater than the sum of the strengths, which are connected by felting or printing be obtained alone. In fact, pressure bonding without felting gave higher strengths than Print joining plus felting.

Example 3

A layer of polyester fibers with a titer of 1.5 and a length of kk.5 mm, which weighed about 26.5 g / m 2, was produced by means of a "Rando-Vebber". The layer is placed on a 16 χ i4 woven tape. The sheet and tape are passed under four strips, each of which contains 20 openings per linear cm in the transverse direction. Each opening is circular with a diameter of 0.127 mm. Water at a temperature of 60 C is sprayed through the openings at a pressure of 35 bar in order to create weakly entangled fibers in a pattern of high-density areas. The speed of the belt and layer under the openings is 13.17 m / min. The lightly matted layer is dried by passing it over a series of steam cylinders.

030035/0787

Portions of the weakly felted fiber layer become self-crosslinking by padding with different amounts Vinyl acrylic terpolymer latex (National Starch Company, NS2853) saturation linked. The ones provided with binding agents Samples are dried at 1 ^ -9 ° C. The unconnected and the Connected layers were gripped for specific tensile strength and tape strength investigated. The results are in the following table 3 compiled.

Comparative example 3

Using the same polyester fibers as in Example 3 a "rosebud" layer is formed with a "hando-vebber" according to the method of US Pat. No. 2,862,251. The applied Water pressure is 14 bar. The layer formed weighs about

28.3 g / m. The layer is dried, and then parts are made of which saturation bound with the binder described in Example 3 and then dried at 1 ^ 9 ° C. The unconnected and the bonded layers are examined for specific gripping tensile strength and for tape strength. The results are also given in Table 3.

«30035/0787

'IfVJt Ai

Table 3

Binding AgentJ salary (%)

Specific gripping tensile strength

(lbs./in./gr./yd .)

Example 3 QR Comparative example 3 QR MR 1.11 MR O, 1 1 O 1, 62 2.36 O, 12 1, 26 2.5 2.73 2.55 1.96 1.75 5 3.23 3.06 2.05 2.99 10 3.61 2.41 2.97 3.30 20th 3.01 2.31 3.48 2.84 4o 3.37 2.91

Binder content

Belt strength (lbs./in./100 grains / yd.

example 3 QR Comparative example 3 QR MR 0.17 MR 0.02 0 0.38 0.55 0.03 0.22 2.5 1.03 0.78 0.33 0.51 5 1.13 0.96 0.57 1, 00 10 1.57 0.91 1, 10 1.56 20th 2.31 0.84 1.48 1.51 4o 2.00 1.54

Ö3QQ3S / 078?

Visual inspection of the above samples shows that the sample according to Example 3 with 2.5% binder is firm enough to be processed and used as a lining in the clothing industry. The sample of Comparative Example 3 with $ 2.5 binder is barely strong enough to be useful, has very poor abrasion resistance and surface fiber anchoring, and does not appear to be sufficient to be of any commercial use. Obviously, the sample according to the comparative example is insufficient until a binder level of 10 % is reached. But at 10 % binder, the stiffness caused by the binder begins to affect usability.

Structural dimension of the fiber entanglement

The unbonded samples of Example 3 and Comparative Example 3 are used for "S", the structural dimension of the fiber entanglement, evaluated. The results were as follows:

Example 3 = 0.0564, Comparative Example 3 = 0.0190

The determination procedure is as follows:

From a structural point of view, this is the extent of the fiber entanglement based on the concentration of the fibers in the felted area (c) and the density of the felted fiber mass (d). That The product of these two factors gives a measure of the frictional engagement and the interaction of the fibers in the felted Area whereby the fibers in the pulp are held in place, which in turn ensures maximum utilization of the Fiber strength is given when the fiber material is exposed to stress. The maximum utilization of the fiber strength is also influenced by the cohesion under stress exhibited by the group of fibers which run between any two matted areas. This

030Ö3S / 0737

Cohesion is inversely related to the factor of the average free length of the individual fibers in group (f),

des t \

The structural measure of the matting and cohesion (S) becomes defined by the following relationship

^S - F

S is, again based on the percentage fiber strength, converted into fiber strength. The relationship corresponds approximates the following empirical equation:

S = 0.0593 + 0.00362 (° / o conversion) + 0.0005 ^ 3 (# conversion) ²

The fiber concentration factor (c) is the ratio of the fiber length in the felted area to the length that would have existed if the fibers had not been patterned and / or felted, ie if the fibers of the fiber were uniformly distributed in the fiber plane. Since there is a direct relationship between fiber length and fiber weight, the fiber concentration factor (c) can also be described as the ratio of the weight per unit area of the felted part (W ₁ ) to the weight per unit area of the total fiber material (W "), ie

c Ϊ1 ²

W ₁ and W "are determined from the fiber sample by direct measurement. An average of 10 values is taken for W ₁ and each value is determined by cutting out the matted mass or a representative part thereof from the pulp with a suitable shape. The area of the mass then corresponds to the area of the shape. All ten samples are weighed at once on a suitable analytical balance.

030035/0787

The density (d) of the matted mass can be calculated by calculating the Volumes of the above excised samples are measured. For this purpose, the samples are mounted axially on broaching tools and photographed 20 times to obtain a cross-sectional view. The cross section thus photographed may have an irregular shape. In this case the shape becomes rectangles and / or Approximated triangles. The shapes are then measured and, using the respective geometric shapes, the corresponding volumes are calculated. The total weight of the 10 samples is then divided by the sum of the 10 volumes, whereby the average density (d) in g / cm of the matted area is obtained. The factor of the average free length (f) of the fibers in the group extending between any two matted areas is given by direct observation (under the microscope) of the fibers in the group and comparison with a standard set estimated.

In practice it is observed that structures made of straight, i.e. non-crimped or curled fibers, sizes of 1 (as there are no bends). Instead, there is always some free length and a suitable one Class size that can be used for structures made of straight fibers is F = 1.4. In the same way it is observed that the size for samples made of conventional staple fiber or lightly crimped filaments is 1.8 to 2.5. For such Fibers can be assumed to have an average class size of 2.1. For highly curled fibers, the measured values of F can be used. The formula for S shows that the free length factor is reversed is related to the strength conversion, i.e. the greater the factor of the free length, the greater the chance of it a low fiber cohesion and the greater the reduction in weight in the unit area of the sample, when it is strained to the point of breakage.

«30035/0787

Claims (1)

Claims 1. Feeter, permanent non-woven fiber material, consisting of a layer of polyester and / or polyolefine fibers, which are made in a regular, repeating pattern slightly matted fiber areas with a higher surface density than the average of the surface density of the layer and from connecting fibers that run between and in the weakly entangled fiber areas are randomly matted together, as well as from an effective amount of an adhesive binder. 2. Fibrous material according to claim 1, characterized in that the fibers consist of polyester. 3. Fibrous material according to claim 1, characterized in that the Fibers consist of polypropylene. k. Fibrous material according to claim 1, 2 or 3 _f, characterized in that the adhesive binding agent is uniformly distributed over the layer. 030035/0787 MUNICH: TELEPHONE (O89) 225585 CABLE: PROPINDUS TELEX O5 24244 BERLIN: TELEPHONE (O3O) 8312O88
CABLE: PROPINDUS-TELEX O184O57 5. fibrous material according to claim 1, 2 or 3 »characterized in that that the adhesive binder is in an interrupted pattern of spaced apart areas of binder is distributed. 6. A method for producing a strong, durable non-woven fiber material according to any one of claims 1 to 5, characterized characterized in that a) a layer of overlapping, intersecting fibers made of polyester and / or polyolefin forms that one b) this layer on a perforated support part imposes that c) to rearrange the fibers into regular, repeating patterns of weakly matted Fiber areas largely columnar liquid jets directed against the supported layer and in that d) an effective amount of an adhesive binder is applied to the rearranged Layer applies. 7. The method according to claim 6, characterized in that the perforated support part has a predetermined topography. 8. The method according to claim 6, characterized in that the Liquid jets are water jets. 9. The method according to claim 6, characterized in that the Fiber is dried to harden the binder at an elevated temperature. O30O35 / 0787