CS215775B1 - Needle-punched fabric - Google Patents

Abstract

The invention relates to a needle-punched separation fabric, intended in particular for primary electrochemical power sources, for air conditioning equipment, impression chambers, waste and process water treatment plants and similar applications. The essence of the invention lies in the fact that the fabric is made of a self-adhesive carrier fabric made of a POP/VS fiber mixture with a basis weight of 18 to 40 g.m-2, with a proportion of 80 to 20% synthetic fibers and 20 to 80% viscose fibers with a predominantly longitudinal fiber orientation and from a fiber fleece with a predominantly longitudinal fiber orientation and from a fiber fleece made of a POP/VS or PAD/VS mixture with a basis weight of 40 to 90 g.m connected to each other by needling with a number of punctures of 60 to 360 o per cm, after which the fabric is heat-treated, synthetic fibers with a fineness of 2.8 to 4.4 dtex are used for the carrier fabric, for the fiber fleece with a fineness of 1.3 to 2.8 dtex. The proportion of synthetic fibers is used to connect the entire structure by the action of pressure and heat on a calender or setting device.

Description

The present invention relates to a needlepunched separating fabric, in particular for primary electrochemical power sources, for air-conditioning systems, automatic milking parlors, wastewater and process water treatment plants and the like.

In the production of primary alkaline cells, various release materials are used between the positive and negative electrodes, but nonwoven fabrics have been increasingly used more and more recently. Their advantage is an even distribution of the fibers in the layer, thus reducing the risk of short-circuiting between the electrodes, while ensuring very easy penetration of the electrolyte. 100% synthetic fibers impregnated in the form of a fleece with various kinds of binders are used in the nonwoven separation fabrics. In the case of burel alkaline cells, however, a hydrophilic proportion of the material is required to wet the separator and suck up the required amount of electrolyte. Therefore, nonwoven fabrics or 100% synthetic fibers are combined with a cellophane layer. The latest trend is the addition of viscose fibers to a chemically bonded nonwoven with a predominant content of synthetic polyvinyl chloride or polyamide fibers. These methods are applied abroad and in Czechoslovakia.

A needled fiber fabric is known according to British Patent No. 1,447,030, which is based on the fact that another set of these yarns is laid transversely on one side and slowed down on a set of one-sided yarns from unfinished carbonizable yarns in the oxidized state. in such a way that the formation thus formed is stabbed from the same side. The resulting fabric may be carbide.

Another known embodiment is a nonwoven wettable battery separator according to British Patent No. 1,461,388, wherein the battery separator comprises a nonwoven sheet of hydrophobic organic oolymer fibers with a wetting agent that is present between the fibers and also on the fiber surface where it has migrated. from the inside of the fibers. Suitable polymers are polypropylene, polyethylene, polystyrene and others. Preferably, two wetting agents having different solubilities in the electrolyte are used.

Also known is a non-woven fabric suitable in particular for an electric accumulator separator and a method for producing the fabric according to French Patent No. 2,123,344. The nonwoven fabric is characterized in that it comprises thermoplastic fibers disposed predominantly parallel to each other and joined by adjustment at the points of contact. The thermo-plating fabric is air-permeable and resistant to liquid chemicals such as battery electrolytes.

Also known are battery separators made of polymeric fibers according to U.S. Patent No. 3,972,759. An improvement in the method of manufacturing nonwoven meltblown nonwoven sheets consists in and / or manufacturing the sheet at a high flow rate of resin that is extruded from a die orifice. at least 0.1 g / min. per hole;

b) collecting the fibers on the receiving device at a basis weight of 100/400 g / inch ² ; c) compressing the fibers to a sheet thickness of 10 to 50 mils and a porosity of more than 40% at a temperature of 5 to 30 ° F below the melting point; d / producing a battery separator with an electrical resistance of less than 0.040 Ohms / inch ² .

All these battery separators have many disadvantages. In the production of promising electrochemical power sources using the described separator materials, the labor of the primary salt producer is increased, the separator becomes more difficult and wet for a longer period of time, and in some cases the content of the release fabric is negatively affected.

These drawbacks are eliminated by needlepunched separating fabrics, especially intended for primary electrochemical power sources, which consists in the fact that it is formed from two self-adhesive bonded backing fabrics of a mixture of POP / VS fibers with a basis weight of 13 to 40 gm with a proportion of 80 to 20 % synthetic fibers and 20 to 80% viscose fibers with predominantly longitudinal orientation of fibers and fiber web of POP / VS or PAD / VS blend with a basis weight of 2 to 40 to 90 gm with a random orientation of the stitching fibers interconnected with a specific number of stitches of 60 to 360 per cm, whereupon the fabric is heat treated.

It is also advantageous that synthetic fibers with a fineness of 2.8 to 4.4 dtex are used for the carrier fabric.

A further feature of the invention is that synthetic fibers of fineness of 1.3 dtex to 2.8 dtex are used for the fiber web.

It is also advantageous that the proportion of synthetic fibers is used to interconnect the entire formation under pressure and heat.

Further details and advantages of the needlepunched release fabric will emerge from the production examples thereof.

Example 1

On a self-bonded carrier fabric of a blend of 80% POPs and 20% VS, with a basis weight of 2 grams of 36 gm, with a predominantly longitudinal fiber orientation, a fiber web with a predominantly -2 transverse orientation of fibers of basis weight of 90 gm is laid. fine fibers 80% POPs 1.3 dtex, 38 mm and 20% VS 1.4 dtex, 38 mm. This fleece is stitched into the carrier fabric using very fine needles 15x18x40 x 3 CB NKU super special with two barbs on two edges, measured by the number of stitches 120 to 160 per cm. The needled fabric is then melted on both sides. The resulting basis weight is 100 gm ^-2 , thickness 0.4 mm. This type of fabric is particularly suitable for alkaline burel cells, and has a water absorption of 0.023 g

of electrolyte per cm '.

Example 2

The fabric is prepared in the same manner as in Example 1 except that the total metal weight is 60 gm and a mixture of 50 POP and 50% VS fibers is used for the carrier fabric and the fibrous web. Instead of adjusting, two-sided calendering is performed.

The fabric is suitable for alkaline burel cells with an electrolyte water absorption of 0.05 g.cm ^-2 , and also for filter hoses for automatic milking parlors.

Example 3

An autohesive backing fabric with a longitudinal grain orientation of 50% POP — 2 and 50% VS with a basis weight of 18 gm is used on which a 20% PADs of 1.7 dtex, 38 ipm and 80% VS 1 is laid, 8 dtex, 38 mm with random fiber orientation, prepared on a pneumatic nonwoven device. The basis weight of the web is 60 g, m ^-2 . Eouno is stitched into the carrier fabric with felting needles 15x18x38 x 3 CB NKU, at a temperature of 165 ° C. The resulting fabric has a basis weight of 70 gm ^-2 , a thickness of 0.35 mm, which is capable of receiving 0.069 g of electrolyte per cm ² .

This type of separating fabric is preferably used for alkaline burel cells and as separating fabric for air conditioners and sewage treatment plants. ’

Example 4

The same carrier fabric is used as in Example 3. Instead of the fiber web, a laminate web is used, one half having 100 POPs of 1.7 dtex, 38 mm and the other half having 100% VS 1.4 dtex, 38 mm. , with a total basis weight of 70 gm and fiber orientation predominantly in the transverse direction. The fleece is laid aside with viscose fibers on the carrier. and then stitched using the same needles shown in Example 1.

The specific number of punctures is 160 to 360 per cm. As a result, both surfaces comprise polypropylene fibers so that they are heat treated by radiant heat at the adjusting device at maximum roller pressure. The finished fabric has a basis weight of 90 gm ^- 2

0.55 mm with the ability to absorb 0.05 g of electrolyte per cm

This type of separating fabric is suitable for alkaline burel cells as well as for air conditioning and waste water filtration.

In addition to the separation of electrodes in electrochemical sources, the individual types of needlepunched separating fabric have also proven to be used for quite different applications, such as in the separation of impurities from atmospheric air and waste water, in milk filtration in automatic parlors.

Claims (3)

1. Needled fabrics containing viscose fibers and heat-bonded polypropylene fibers, intended in particular for primary electrochemical power systems, for air-conditioning systems, automatic parlors, sewage and process water treatment plants and similar applications, characterized in that it is made of an self-bonded carrier fabrics of a mixture of POP / VS fibers with a basis weight of 18 to 40 gm, with a proportion of 80 to 20% polypropylene and 20 to 80% viscose fibers with predominantly longitudinal orientation of the fibers 2 40 to 90 g.m. with a random or predominantly transverse orientation of the stitched fibers having a specific number of stitches of 60 to 360 cm. 2. Needle-punched release fabric according to claim 1, characterized in that polyDropylene fibers having a fineness of 2.8 to 4.4 dtex are used for the carrier fabric. 3. The needle-punched textile fabric of claim 1, wherein polypropylene or polyamide fibers having a fineness of 1.3 dtex to 2.8 dtex are used for the fibrous web.