NL7808294A - NON WOVEN TEXTILE MATERIAL FOR FILTERS. - Google Patents

Description

r j __ J * / N.O. 26Λ67

The Kendall Company of Walpole, Massachusetts,

United States#

Non woven textile material for filters #

The invention relates to non-woven textile material for filters consisting of cellulose fibers and to a method for the manufacture thereof.

Many liquids, in particular potable liquids such as milk, beer, wines and the like, are subjected to a filtration process during the processing, in order to remove unwanted sediments. For example, in the case of milk, it has hitherto been common practice to produce the milk produced on farms. a layer of flannel or by filtering several layers of gauze.

The considerable cost of woven textile materials made it desirable to regenerate the filter after each use, ie wash and rinse the flannel or gauze in such a way that no traces of sour milk can remain that could contaminate the next batch of milk. cleaning is laborious and involves a lot of work and was often carried out ineffectively or even skipped. Dairy hygienists responsible for milk quality have therefore for a number of years already recommended the use of disposable filters or single-use filters in the form of discs or square pieces, and such filters are now being extended in practice applied #

In the production of milk in a dairy, it is common practice to pass the liquid milk through a metal filter provided with a filter pad at the bottom. # To facilitate cleaning, such filters are generally round with no slots or corners and the filter pads are circular and are referred to as discs # For the sake of simplicity, such filter pads are referred to as filter pads regardless of the actual shape of the filter pad in the present case.

Hitherto, nonwoven filter disks have been manufactured. die cutting of a carded or combed or brushed piece of bleached cotton fiber and in some parts of the world still use such discs 1 # It turned out early on! because such discs have certain disadvantages. Be in bulk. they are difficult to separate from each other and especially during use, the fibers tend to deform and separate, causing thin sections in the disc to allow sediment to pass through. ”, As was commonly called, was observed especially when attempting to speed up the filtration process by lifting the metal filter and dropping it onto the rim of the larger milk canister in which the milk is collected # 15

Attempts to avoid the stated drawback first yielded nonwoven filter disks, the surfaces of which were bonded by starch, dextrin, or food-grade gums # Later, greater wet strength and tear strength in use could be achieved by bonding the filter material by calendering a piece of cotton fiber and thermoplastic fiber at elevated temperature, which; is described in U.S. Pat. No. 2,333,53Ί or by using polymeric binders as described in U.S. Patent 3,367,706 · 23

However, the known methods which provide higher strength wet strength filter disks have a significant economic disadvantage. The nonwoven textile material coming from the feed is generally wound in several layers on a spool from which the material is removed , laid flat on a cutting table and stamped into piles by means of round-shaped punches. Discs of non-woven textile material are known to have a loss factor of 35-40% and greater depending on the blanking method. Since the waste material is 35; or other bonded material, the recovery of the valuable fiber material from the waste materials by dissolving chemicals to remove the binder followed by rinsing and drying the recovered fibers is an expensive process. In addition, some binders used for the manufacture of non-woven textile material by any chemical method are not easily removed with some treatments, which also make the fibers brittle,

Pogiqpn have been made to improve the strength of the binder-free fibrous pieces by a pressure treatment, especially between elevated temperature calender rolls with a smooth surface or with a surface in relief.

If pieces of cotton fibers or pieces of mixtures of cotton fibers and viscose fibers are treated according to this node, an increase in strength is observed. However, if the percentage of the viscose fibers in a mixture of cotton and viscose is increased, the strength of the product subjected to the pressure treatment decreases sharply; a mixture of 75 wt viscose and 25 wt cotton has a considerably smaller strength than a mixture of 75 wt cotton and 25 wt viscose Filter discs consisting of an excess of viscose fibers which have only been subjected to the pressure treatment bonded due to its weakness and tendency to deform or tear during use ineffective, presumably due to the characteristic nature of cotton fibers compared to viscose fibers; cotton fibers are naturally curled, twisted and wound, while viscose fibers are less likely to be confused, even if they are crimped. For economic reasons, it is desirable to replace the cotton fibers in a filter disc with viscose fibers, since cotton has become relatively expensive and also requires a costly rinsing, bleaching and drying process before the material can be used to filter potable liquids. It is virtually impossible to deform raw cotton fibers with any degree of permanence by a pressure treatment,

Surprisingly, it has been found that the lubricant or sizing used for viscose rayon cotton or commercial fibers can be changed to have a great effect on the strength of nonwoven fabric consisting of such fibers. has. In order to facilitate the opening, folding and carding of cellulosic fibers, it is common in textile practice to treat the fibers with a size which is generally a size based on a "soap fatty acid" (sodium oleate oleic acid) and that on the fibers in an amount of 0.2-0.4 wt.%, based on the weight amount of the fibers, is applied. Such soap-fatty acid-based preparations facilitate the processing of the fibers, but they do not function as a binder. Therefore, the strength of the fibrous stitches subjected to the pressure treatment decreases as the percentage of the viscose rayon fibers in a mixture of cotton and viscose increases, as has already been stated.

The invention relates to non-woven textile material, in particular a pressure-treated fibrous piece at least partly consisting of cellulose. fibers containing as a finish a liquid aliphatic polyhydroxyalkanol which is free or substantially free of fatty acids.

The invention also relates to a process for the production of a non-woven textile material, which comprises the process steps of forming a fibrous piece consisting of at least partly cellulose fibers which as a finish comprise a liquid aliphatic polyhydroxyalakanol which is free or substantially free of fatty acids, after which the obtained fibrous piece is subjected to a pressure treatment.

The cellulose fibers contain an aliphatic polyhydroxyalkanol such as glycerol as finish in an amount of 0.05-0.50 wt.%, Preferably 0.1-0.3 wt.%. Such cellulose fibers can be advantageously manufactured using the devices which are conventional for the production of non-woven textile material. When mixed with other cellulose fibers and carrying out the printing process, it appears that non-woven textile material obtained by the process of the invention results in an unexpected has great strength, for which no explanation has yet been given.

Furthermore, 35-40% by weight of the material from the waste material 7808294-5 * 5 from the die-cutting of filter discs can be recovered and reused by subjecting the material to the usual operations, ie opening of the fibers, folds and carding. According to the method of the invention a bond from fiber to fiber is obtained, but the binding is more or less weak and cannot be compared! with the bond obtained between thermoplastic fibers or polymeric fibers by application of heat · Effectively, the conditions of the process are adjusted such that the machine direction strength in the dry state of a strip of the material with a width of 5 cm does not exceed 2000 g, so that the recovery process of material from the waste and its recycling can be efficiently carried out, without the need for special operations.

Examples · 15

The filter disks in the following examples were all produced by elevated calendering of a piece of superimposed carded nonwovens.

Example I.

A series of four marketed filter discs, 20 from different manufacturers, were examined for the usage properties and the physical properties. Each of the filter disks consisted of about 50% by weight of bleached cotton and 50% by weight of viscose rayon provided with a conventional finish * The physical properties of the filter disks were the following: 2

Average weight h6 g / m, Average tensile strength. of a 5 cm wide machine direction strip in the dry state 230 g 30

Average flow time 36 sec

Average sediment retention 46% of 50 µm particles

The flow time is the time in seconds required to flow a given volume amount of the liquid through a filter disc: the sediment retention is the percentage of the sediment, with a standard particle size f obtained on the filter disc used. The stated two values are 7808294 ί «·. 6! were determined in standardized laboratory tests.

These values indicate the properties of a filter disc when used. They are not an absolute measure of use on a livestock farm, as the mode of use can be influenced by local conditions, such as temperature and 5 l! the viscosity of the milk, the presence or absence of udder inflammation in the animals, etc., and the nature of the sediment, or the presence of either coarse flakes and hair, or fine zinc. In correlation with open field trials under different conditions are a number of standard variables indicating whether or not a filter disc is effective.

Example II.

The mixture of 50% by weight bleached cotton and 50% by weight ordinary 1.

viscose rayon was replaced with a mixture of 50 wt% bleached 15 | cotton; 25 wt% ordinary viscose rayon and 25 wt% viscose rayon with a glycerol finish of 0.15 wt% · The physical properties were as follows: 2

Weight W g / m

Tensile strength, machine direction 20 of a 5 cm wide strip of the material in the dry state 610 g 1 Flows 36 sec. Sediment retention 52 $ of 50 yum particles

The tensile strength of the product obtained was a factor. 2.65 larger-than-year range of products on the market consisting of similar mixtures of cotton and viscose

As the percentage of viscose with glycerol as a sizing in the fiber mixture increased, the strength of the filter material obtained therefrom also increased. 30

Example III

A filter disc of 100% by weight viscose rayon with 0.15% glycerol as finish had the following properties; 2; Weight ^ 8 g / m

Tensile strength ·, of a 5 cm wide 35 strip:

When dry in machine 2000 g 1 direction 7808294 7

In the dry state, transversely 50 ° g

When wet, machine direction 225 g

In the wet state, in the transverse direction 7 ° g

Flow time 27 sec

Sediment retention 62 # of particles 5 'of 50 µm.

A filter disc for comparison with an equal weight, however, consisting of 100% by weight viscose fibers with a commercial soap fatty acid as finish was unsuitable as a commercial product, since the material had insufficient tensile strength; in the dry and wet state and since the filter disc tended to deform, creating thin spots during use causing reduced sediment retention, resulting in undesirable quality milk

In general, in filter discs consisting of cotton fibers, viscose fibers or mixtures thereof, an increase in the tensile strength in the wet and dry state can be achieved if the usual size of a soap fatty acid is replaced by a glycerol sachet according to the invention

An amount of viscose fibers of at least 25% by weight, provided with a glycerol finish, causes the strength of a viscose / cotton mixture to double as stated before. If the filter material contains an important amount of viscose fibers, it is customary to adjust the flow time relative to the percentage of sediment retention by mixing coarse viscose fibers (10-20 denier) with finer viscose fibers (1.5-5 denier), depending on the nature of the filtering liquid and the sediment to be removed · In general, the use of coarse fibers provides relatively short flow times, but this is at the expense of sediment retention, which is to be expected · It is obvious among experts that the desired balance between flow time and sediment retention can be achieved by mixing fibers of different denier values # According to a preferred embodiment of the invention w fine viscose fibers, of, for example, 2.2 55 denier, combined with an appropriate amount of viscose fibers of greater denier, for example, 10 denier, while 7808294

Claims (10)

Textile material according to claim 1 and / or 2, characterized in that the cellulose fibers with the polyhydroxyalkanol as finish comprise an amount of 25-100% by weight. 7808294 on the weight amount of the textile material. Textile material according to claims 1 to 3, characterized in that the cellulose fibers consist of a mixture of coarse viscose rayon fibers of 10-20 denier and finer viscose rayon fibers of 1.5-5 denier. 5 Textile material according to claim, characterized in that only the finer viscose-rayon fibers are provided with the polyhydroxyalkanol finish. 6. Textile material according to claims 1-5, characterized in that the cellulose fibers consist of a mixture of bleached cotton fibers and viscose-rayon fibers. Textile material according to claims 1-6, characterized in that the aliphatic polyhydroxyalkanol is glycerol. Textile material according to claims 1-7, characterized in that the tensile strength of the textile material in the form of a 5 cm wide strip is not more than 2000 g. 9. Textile material obtained using the method according to example II or III. 20 10. A process for the production of a non-woven textile material for filters, using the working steps for forming a fibrous piece, at least partly consisting of cellulose fibers, characterized in that the cellulose fibers are treated with a liquid aliphatic polyhydroxyalkanol which is free or is substantially free of fatty acids as size, after which the applied fibrous piece is subjected to a pressure treatment. 11. A method according to claim 11, characterized in that the fibrous piece is subjected to a pressure treatment by calendering. 12. Process according to claim 10 or 11, characterized in that viscose rayon fibers are used as cellulose fibers to be sized with the polyhydroxyalkanol. 13. Process according to claim 12, characterized in that a non-woven textile material is manufactured in the form of a piece, the fibrous piece of which consists of a 7808294 mixture of viscose-rayon fibers which have been sized with the polyhydroxyalkanol and other viscose rayon fibers that are not coated with the polyhydroxyalkanol 14. Process according to claim 13, characterized in that non-woven textile material is manufactured in the form of a piece, the fibrous piece of which consists of 10-20 denier viscose-rayon fibers which are not sized with the polyhydroxyalkanol and viscose. 1.5-5 denier rayon fibers which have been sized with the polyhydroxyalkanol. A process according to claims 10-14, characterized in that a non-woven textile material is produced in the form of a piece on which the fibrous piece consists of a mixture of bleached cotton fibers and viscose-rayon fibers * 16 * A method according to claims 10-15, characterized in that non-woven textile material is manufactured in the form of a piece, the fibers of which are treated in the fibrous piece and in such a way proportions are mixed that the obtained nonwoven textile material has the property in the form of a 5 cm wide strip, to have a tensile strength in the dry state n of not more than 2000 g. 20 *! 7808294