DE1652921A1 - Abrasive grain backing fabric made from regenerated cellulose fibers and process for their production - Google Patents

Description

DR. WALTER NMELSCH

Pa '-. Viionwolf'

SdilosssiroOe -12. P.O. Box 10914 ^{File 2102}

Telephone: 652 97 07 1 R R 9 Q 9

Applicant: REICHHOLD CHEMIE AKTIENGESELLSCHAFT ^{IÖJ £ 3} * '

Hamburg 70, Iversstr. 57

Ski grain carrier fabric web made of regenerated cellulose fibers and methods of making them

For the production of high-quality abrasive fabrics that are used in Form of grinding belts for mir-chin grinding in the metal and the woodworking industry are used in a variety of ways, primarily cotton fabrics are used. As a fabric construction For example, a twill fabric (2: 1) with a thread count per cm of 3 ^ / 20.5 made of cotton yarn is an option the strengths of 20/28 m / g? the fabric weight of the desized

Fabric is approx. 235 g / m. Such a fabric has a breaking load of approx. 23 kp / cm in the warp direction with an elongation at break of 17 $, while the corresponding tensile strength values for the weft direction are up to a breaking load of 10 kp / cm and an elongation at break of 8% . (Strip tensile test on textile fabrics according to DIN 53-857. The result obtained was divided by 5 in order to convert the 5 cm wide test strip to 1 cm.)

Because abrasive cloths are made up as sanding belts in their Direction of use, that is the warp or lengthwise direction of the Fabric, may only have a very low elasticity, otherwise there is a risk that the sanding belts will move under the influence of the

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excessively long the tensile stress and run down from the contact disk of the grinding machine, it is necessary to subjecting such fabrics to a stretching process during the finishing process in the wet state, which is fixed by incorporating finishing agents after the fabric has dried. A finished abrasive carrier fabric on the basis of the type of cotton fabric mentioned above, is.B. the following properties: (for comparison is in the right Column the corresponding raw fabric is listed again).

Finished raw fabric

Tissue (deflated)

Average surface weight 315 g / m ² 236 g / m ² Tear strength in warp

direction Ho kp / cm 23 kp / cm

Elongation at break 6.5 % Π%

Tear strength in

Weft direction 12.6 kp / cm Io kp / cm

Elongation at break 20 % B %

One can see that the originally in the warp direction opposite the Weft direction existing greater elongation during the tearing process is significantly reduced by the stretching and finishing process while the stretch in the weft direction increased significantly - in other words: It was made by the stretching and finishing process used in the Existing stretch in the warp direction partially moved in the weft direction. Has a fiber material based on baura wool ideal conditions for it when wet in the warp direction to move forward strongly. For cotton fibers or fabrics

namely takes the elongation at the beginning of the tearing process Already with a small force it increases, so that it hardly increases with further tensile stress, i.e. es is possible, cotton fibers and, accordingly, cotton fabrics to be equipped with largely little stretch in the warp direction by means of a wet stretching process.

The disadvantage of using raw abrasive fabrics based on cotton is that they are relatively complicated subjected to prepared dry and wet finishing process must be equipped before they can actually be equipped, i.e. finished. The reason for this lies in the fact that one is used for the manufacture of abrasive cloths Highly absorbent carrier fabric is required, as only these meet the requirements for perfect adhesion of the finishing agents and binders to the fabric.

Cotton, however, contains growth accompanying substances of a waxy and fat-like nature, which significantly impair the wettability and induce absorbency of the fabric and only through intensive, costly finishing pretreatments, such as Desizing, alkaline boiling and cupping - each in connection with numerous rinsing processes - can be removed can.

There has been no shortage of attempts to create abrasive fabrics made from cellulose i.e. made on the basis of regenerated cellulose. As far as it is low-quality abrasive cloth sheets for manual grinding operations, this is

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Already practiced with success for years. So far, however, it has not been possible to produce cellulose fabrics for high quality Abrasive grain carrier fabric webs that are suitable for the production of abrasive fabric tapes for machine sanding, to use. This is due to the fact that cellulose fabrics of the conventional type have a strong impact on cotton fabrics have reduced wet strength compared to the corresponding strength values in the dry state. Furthermore is their swelling value - better water retention capacity - is significantly higher than that of cotton fibers. It is also known that . in the case of cellulose fiber types, there is largely proportionality between the force applied and the elongation that occurs; it is therefore It is not possible to fix the viscose fabric with little stretch by mechanical stretching during the wet finishing.

However, the latest developments in the field of pulp fibers have resulted in cellulose materials that can be found in their Both dry and wet tear behavior are very close to that of cotton. You can even find that the dry strength such cellular wool materials is significantly higher than that of cotton, while their elongation behavior during the tearing process in both dry and wet condition largely corresponds to that of cotton fibers. At this stage of development of cellulose fibers are fibers made from regenerated cellulose, in particular from the Polynosic group, the represents a specific term within cellulose technology. (To prevent all possible fiber types from regenerated cellulose are called polynosic

denj has the Association International Polynosic (AIP) certain Requirements of a technical nature which must be met by Polynosian pasers.) It would be of general advantage in the manufacture of abrasive fabrics to use cellulose fabrics from regenerated cellulose, in particular from the Polynosic Group as abrasive raw cloth, as these are much less complicated due to their natural cleanliness in wet equipment are to be treated as normal cotton fabrics.

The disadvantage is that the conventional warp thread-sized abrasive carrier fabric, due to the conventional Sizing, have anti-adhesive character compared to the conventional finishing binders to be applied later and therefore traditionally absolutely must be desizing, moreover have abrasive backing fabrics made from regenerated cellulose, especially the Polynosic group compared to desized ones Cotton fabrics have a much greater absorbency and thus absorb significantly more finishing agent, which in turn causes the Finishing process is made more expensive.

Furthermore, the tear resistance becomes normal! · Abrasive raw cloth on the basis of regenerated cellulose, especially polynosic fibers, greatly reduced.

It has now been found that the disadvantages outlined above can be avoided by using an abrasive grain carrier fabric web made of regenerated cellulose fibers, in particular of the polynosic fiber type, which is characterized by this is that

a) the warp thread sized and finished and the size and finish is firmly bonded without a boundary layer and

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b) a weft thread has a finish.

A special embodiment of the Sehleifkarnträgerewebbahn is characterized in that the warp thread is provided with a core size (core size - see magazine ADHÄSION, year 1961, No. Io - pages 505-512, and No. 11 - pages 564-577 and Ho. 12 - Pages 617 - 622 in the article on "Sizing agents for the textile industry ¹¹ by Erich P. Prieser.)

In a further embodiment, the abrasive grain carrier fabric web is characterized in that the finish located on the warp thread and weft thread by finishing with a finishing agent, which contains organic solvent emulsified in the aqueous medium, which at temperatures a swelling agent from 15 - 45 ° C and above 65 - 200 ° C a solvent for the size on the warp thread has been arranged.

Has an abrasive grain carrier fabric web produced in this way the great advantage that the abrasive cloth finish adheres firmly is firmly connected to the core sized warp thread and the weft thread.

In the production of the present web of abrasive grain fabric backing, there is the advantage that none during the finish large amounts of finishing agent have to be applied because the warp thread is already core-sized. Also will thanks to the new arrangement in the abrasive grain carrier fabric web, a high level of elasticity is achieved.

1098Ί% 70409

The following can be used as size for the warp thread or, preferably, core size: degraded starch and starch derivatives, Synthetic resins based on isocyanates, homo- and / or copolymeric acrylic compounds (butyl, methyl acrylates), Polyvinyl alcohol, polyvinyl acetate, aeryl-nitrile-butadiene-styro! Copolymers in the form of solutions or dispersions and appropriate wetting agents, e.g. naphthalene sulf onates, acrylic derivatives or ethoxy adducts.

Preferred core sizes are polymers based on acrylates and their derivatives, as well as acid-degraded starch products and fatty acid condensation ethoxy adducts. As a finish for the warp thread and for the weft thread, for example, are: animal hide and / or reactive and non-reactive copolymeric acrylate solutions or aqueous dispersions, polyisocyanates, polystyrene, N-. ^T iethylol compounds of urea and its derivatives, aldehydes and its derivatives, sulfone compounds, phenol-formaldehyde resole resins, polyvinyl alcohol, acetate and chloride in the form of dispersions and solutions, epoxy and polyester resins as well as starch, starch derivatives and ethoxy adducts, including these contain organic solvents emulsified in the aqueous medium, which are a swelling agent at temperatures of 15-45 ° C and a solvent for the size on the warp thread at temperatures above 65-2oo ° C. Suitable emulsifiable organic solvents are, for example, toluene, xylene, ethyl acetate, white spirit, trichlorethylene, perchlorethylene. Preferred finishing agents are self-crosslinking copolymeric acrylate dispersions, in particular

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special copolymers based on butyl and ethyl acrylate as well as methyl methacrylate in dispersion or solvent-based form.

By using the preferred finishing agents, the following special advantages are achieved, since the crosslinking acrylate dispersions as a finish to the phenolic base resins to be applied later, they also have good adhesive properties this avoids embrittlement of the tissue. In addition, the abrasive grain carrier fabric web can be used on both Sides of the web be provided with the same finish, such as by a dipping process or a double-sided coating process is achieved

example 1

A warp yarn of strength Nm 28 / 3o made from regenerated cellulose fiber (Polynosic type) is placed in a sizing trough with a Recipe, consisting of

8o parts by weight more unlocked by acid degradation

strength
3 parts by weight of ethoxy adduct

917 parts by weight of water

core-sized and dried on a cylinder drying machine and then woven into a raw abrasive fabric. The raw abrasive cloth produced in this way is without desizing with a finish consisting of

5o parts by weight of animal hide glue (3oo leaf size, loo mp) loo parts by weight of a copolymeric acrylate dispersion 5o parts by weight of kaolin
3 parts by weight of naphthalene sulfonate

797 parts by weight of water

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impregnated and dried and fixed with simultaneous stretching with a lateral penetration of approx. H ₃ 5 %.

Example 2

A warp yarn made from regenerated cellulose fibers (Polynosic type) the Nm 26 is placed in a sizing trough with a liquor, consisting of

12o parts by weight of reactive copolymeric acrylate dis-

persion
5 parts by weight of water-soluble copolymer

30 % acrylic acid, 70 % butyl acrylate, 875 parts by weight of water

sizing and then in an air duct at 14o ° C dried and fixed. After weaving, the raw abrasive cloth is immediately treated with a finishing solution without desizing. consisting of

12o parts by weight of reactive copolymeric acrylate dispersion

5 parts by weight of a copolymer of 3o % acrylic acid and 7o % butyl acrylate 2o parts by weight toluene

6o parts by weight of kaolin

2o parts by weight of dimethyloldihydroxyethylene urea

2 parts by weight of magnesium chloride 773 parts by weight of water

impregnated and dried with stretching at 1 ^ O ⁰ C - the fabric jumps in width by 11.5 % , and fixed.

As proof of the technical port step, the after Example 1 and 2 treated sheets obtained as follows; A final line is then stamped using Starch and cross-linking acrylate dispersion based on methyl, ethyl, butyl, methacrylate, acrylonitrile butadlene

- Io -

1662921

Styrene and on the grain side a spread consisting of a copolymer Acrylate dispersion and its derivatives and epoxy resin. On the abrasive backing fabric prepared in this way a phenolic resin base coat and then the abrasive grain as well as the phenolic resin topcoat applied. The abrasive belt obtained has an excellent bond between Basic impregnation and finishing.

The further treatment takes place as indicated in Example 1. The abrasive cloth tape obtained shows a good bond, good flexibility, high wet strength and good adhesion of the finish to the non-desized fabric «

The soft soap carrier fabric finished according to the invention After impregnation, it is further treated in the conventional way according to the intended use, e.g. coated, dried and calendered on the stamp and grain side.

To test the achieved adhesive effect, the prepared soft abrasive carrier fabric was primed with phenolic resin and then, electrostatically, abrasive (electro corundum or silicon carbide) grain no. ho applied and pre-dried or pre-hardened on the slope. Then the second layer of binder was applied with a phenolic resin binder with appropriate filler and dye additives and the entire system was again dried on the slope and then cured. After the hardening process, the soft soap carrier fabric was

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Creation of its hygroscopic equilibrium in a humid air conditioned atmosphere and then rolled up. The abrasive fabric produced in this way was then subjected to a mechanical breaking process - referred to in the technology of abrasive fabric production as ^M Flexem "- and processed into abrasive fabric tapes. These were stretched on a belt sander and tested in the test grinding process Sized, then not desized and then conventionally finished abrasive carrier fabric compared using a test grinding technique. With constant pressure load, the grinding was carried out from a defined iron pipe. Furthermore, the surface of the abrasive fabric was visually inspected after the test grinding process with regard to abrasion and grain breakage In addition, the adhesive strength of the abrasive fabric finish was improved by applying an intermediate layer of phenolic resin and Casing of this sample was tested on sheet metal using the same phenolic resin. The sample was cured and, after air conditioning, the peel strength and the peel point were determined.

breakage of tissue after:

Conventionally sized abrasive fabrics are not desized and conventionally impregnated

According to the innovation, finished dead Abrasive tissue lait the sight seal according to the invention and finish impregnated

1 minute

12 minutes

6 kg between

Sizing and finishing

15 kg between

Phenolic resin and finish

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2102 Pat

- 12 -

The tests show that the abrasive grain carrier fabric web according to the present innovation is surprisingly improved in several respects.

The abrasive grain carrier fabric web according to the innovation is illustrated by the drawing.

Figure 1 shows: under A the core sized and finished warp thread A without boundary layer and finished weft thread B.

The process for producing the marked abrasive grain carrier fabric web has the characteristic that the warp thread is sized, preferably core sized, Warp thread and weft thread are woven into the fabric web and then the fabric is finished.

Claims (4)

2102 claims 1. Abrasive grain backing fabric made from regenerated cellulose fibers, in particular of the polynosic type, characterized in that a) the warp thread is sized and finished and the size and finish are firmly bonded without a boundary layer is b) the weft thread has a finish. 2. Abrasive grain backing fabric web according to claim 1, characterized in that that the warp thread is provided with a core size. 3. Abrasive grain carrier fabric web according to claim 1 or 2, characterized in that the on the warp thread and the Finishing on the weft thread by finishing with a finishing agent which emulsified in the aqueous medium contains organic solvent, which at Temperatures of 15 - ¹ IS ⁰ C a swelling agent and U4 £ _O YyU4t £ 65 - 200 C simple solution for those on the warp thread located size is, is arranged. 4. A method for producing the abrasive grain carrier fabric according to one or more of claims 1-3 »thereby characterized in that the warp thread is sized, preferably core sized, warp thread and weft thread to fabric web and then the fabric is finished. 109818/0409 it Blank page