DD146634A1 - METHOD FOR PRODUCING AN IMPREGNATION LATEX FOR NEEDLE FELT - Google Patents

Abstract

According to the process of the invention for the production of an impregnation latex for needled felt, a mixture of a) 45 to 55% of a carboxy latex with a butadiene content of less than 48% by weight is used. and b) from 45 to 55% of a butadiene latex having no functional groups and having from 48 to 55 parts by weight. Butadiene content produced. This mixture for impregnation of needled felt, preferably of synthetic fibers, is characterized by high mechanical stability, does not form deposits on the nip rolls in the felt treatment. The impregnated needle felt has very high Florerholung and Maszstabilitaet. The textile character of the needle felt is maintained.

Description

giter of the invention

Process for producing a needle felt impregnation latex

Field of application of the invention

The invention relates to a method for producing a needle felt impregnation latex which is particularly suitable for needled synthetic fiber felts. It is characterized by permanent fiber incorporation with high abrasion resistance while maintaining the textual character of the treated needle felt. ·

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Characteristic of the known technical solutions

It is known to use carboxylated butadiene copolymer latices for the impregnation of needle felt by the method of bulk impregnation (CA. TEX 27 (1), 48-53 (1968)). Although carboxylated Butadiencopolymerisatlatices well because of their better adhesion to the fiber, in contrast to other latexes for the impregnation of needle felt, but they have the particular disadvantage that drying temperatures of about 120 ⁰ C are required. This is achieved in use of synthetic fibers in the web, such as, B ₀ polypropylene fibers having a relatively low melting point, and a problem results in that at lower temperatures the drying times have to be extended. The economics of these methods for needle felt impregnation is therefore reduced.

In DD-PS 129 924 a latex for impregnating needle felt is described which comprises a binder mixture of Diencopolymerlatex with 1 to 5 % carboxyl-containing monomers and an aqueous solution of 1 to 15 % of the total solids content of a reactive substance such as melamine-urea, phenol -, epoxy resin, ethylenediamine, dicyandiamide represents. The reactive substance is admixed during the preparation of the copolymer at a monomer ratio of between 85 and 100 % . Very good adhesion of the binder to the fiber at low drying temperatures without prolonging the drying time is achieved. Although a needle felt with latex according to DD-PS 129 924- has improved properties and is more economical to produce, the disadvantage is an unsatisfactory mechanical stability, so that after some time more or less strong deposits form on the impregnating, the

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are very difficult to remove. Another disadvantage is that the addition of the reactive substance is very critical and must be done exactly at a certain conversion of CarboxyHatex, otherwise a coagulation may occur «

Object of the invention

The aim of the invention is to achieve a sufficient adhesion of the binder on the fiber in the impregnation of needle felt, in particular of synthetic fibers, with latex and to maintain the textile character of the needle felt despite the use of the Vollbadimprägnierungssystems. Next, the latex should not only have good storage stability but also high mechanical stability and, in particular, form less or no deposits on the padder rollers.

Explanation of the essence of the invention

The invention has for its object to develop a method for producing a impregnation latex for needle felt, which meets the above requirements.

The object is achieved in that a mixture is prepared

a) 45 to 55 % of a Carboxyllatex with 40 to 48 parts by weight of TIn. Butadiene, 35 to 59 parts by weight of TIn. Styrene and / or acrylonitrile and 1 to 5 parts by weight of TIn. one or more vinylidenecarboxylic acids in the polymer molecule and

b) from 45 to 55% of a butadiene latex without functional groups with up to 48 ^ by weight tin. Butadiene and 45 to 3% by weight of TIn. Styrene in the polymer molecule.

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The latexes can be prepared by a conventional procedure? Thus, they can be prepared by the so-called batch process or by a semi-continuous monomer feed process by polymerization in aqueous emulsion. In this case, a portion of the monomers, generally from 5 to 25 % of the total amount, is initially charged, the polymerization is started by addition of initiator and the remainder of the monomers is continuously added in accordance with the conversion. In the submitted part of the monomer mixture, the monomer ratio may differ from the rest of the monomer mixture.

In the batch process, all components are placed in the reactor vessel and reacted at the desired temperatures to about 100 % .

The choice of monomers is crucial for the formation of latexes with desired properties. Thus, it is essential that the two latexes blended into a needled felt impregnating latex according to the invention have different levels of butadiene, ie the butadiene content should be below 4-8 % for one of the latices and above 4-8 % for the other, and only one The latices may contain functional groups. These functional groups must consist of COOH groups introduced by co-polymerization of ethylenically unsaturated carboxylic acid. Also combinations of monocarboxylic acids, such as acrylic acid and methacrylic acid, or combinations of mono- and dicarboxylic acids, such as. As acrylic acid and fumaric acid or itaconic acid can be applied.

It can be the usual anionis.chen emulsifiers, ζ. Β. Alkali salts of long-chain alkyl sulfonates] !, alkyl

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aryl sulfonates or long-chain alkyl sulfates are used »

Auoh combinations of anionic and nonionic emulsifiers _f such as ζ. B. reaction products of ethylene oxide (5 to 50 mol) with phenols (1 mol), further reaction products of alkylene oxides and fatty alcohols are suitable.

For activation, the customary water-soluble free-radical formers, in particular the alkali metal salts of peroxodisulfuric acid, eg. As ammonium persulfate, potassium or sodium persulfate. Reducing agents such as formaldehyde sulfoxylate or sodium bisulfite can be used in smaller quantities.

Polymerization is preferably carried out between 50 and 80 ^° C. The preparation of the latex with functional groups should initially be carried out at a pH of from 3 to 4 and towards the end of the polymerization below 7, the pH of the other latex must be above 8. The mixture of the two latexes should subsequently be adjusted to a pH of more than 8, preferably between 8 and 9.

As the main monomers, nebeo butadiene can be used in the amount of styrene according to the invention, .alpha.-methylstyrene, acrylonitrile or other vinylaromatic compounds or aliphatic monomers. For economic and procedural reasons, however, styrene and / or acrylonitrile are preferred.

For controlling the molecular weight of. In the case of polymerization, polymers may contain the usual regulators,

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such as mercaptans, for example tert-dodecyl mercaptan, halogenated hydrocarbons, such as carbon tetrachloride, or aliphatic alcohols and aldehydes, such as formaldehyde, methanol, etc. are used.

Furthermore, after the end of the polymerization, the usual auxiliaries, such as anti-aging agents and bactericides, may be added to the latex.

embodiment

The physical data listed in the following examples were determined as follows:

Mechanical Stability: According to DIN 53 567 is a latex sample, in the specified in DIN 53 567 apparatus, starting at 35 ⁰ O, the Scherbeanspruohung a 14,000 U / min - / exposed to 200 rpm rotating disk. The formation of microcoagulum or of coarse precipitates by filtration and weighing after 10 minutes shearing stress is evaluated.

Florreholung: The Florerholung is after the TGL 16-665 128/01 with a stress level of 2000

p / cm and a loading time of 2 h. Dimension of the test piece: 10 cm χ 10 cm

Testing and recovery takes place at room temperature. After 2 h and 20 h recovery, each time with a thickness

knife, adjusted to 5 p / cm, the thickness of the specimen measured.

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Thickness of specimen after recovery Initial thickness of specimen

χ 100 = Flor recovery (%)

Dimensional stability: Ss the permanent elongation of impregnated needle felt samples is measured.

For this purpose, 5 μm wide strips of 10 cm free clamping length in the dry and wet state are loaded with 5.10 and 15 kg in a needle loop. Elongation is measured immediately after loading and after 1 h.

example 1

After the addition process, a latex was prepared from; '

Condensate 106 parts by weight.

EDTAs (ethylenediaminetetraacetic acid2e) 0.085 gevn-tle.

Sodium alkyl monosulfonate 2j1 ""

Ethoxylated Alky! Phenol 2,3 ""

Potassium persulfate 0.65 ""

Methacrylic acid 2 ^fl.

ijert. Dodecylmercaptan .0.6 ""

Butadiene. 45.9 ""

Acrylonitrile 33 »^ -" "

Styrene 20.7 ""

The polymerization was carried out at 50 to 52 ⁰ G. The initial pH was 3.4 and the final pH after the polymerization was 5.9. After the polymerization, the latex was brought to a pH of 8.2 with a total solids content of about 50% , The latex is further called latex A.

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Example 2

At 80 ⁰ C, a latex was prepared; out:

51 wt _o -Tln. Butadiene and 49 parts by weight of TIn. Styrene, other ingredients were:

1.2 parts by weight. Sodium lauryl sulfate, 0.7% TIe. Potassium persulfate, 0.2 parts by weight. Sodium bicarbonate, 0.8% TIe. Carbon tetrachloride, 0.05% by weight. 'EDTA and 104 parts by weight. Condensate. The pH was initially 8.6. The total solids content was adjusted to about 50%. The latex is still called latex B.

Example 3

A latex was prepared according to Example 2, wherein only the monomer mixture was changed as follows: butadiene 4-7 Gevsu-Tle. and styrene 53 wt. Tie. Further, no changes were made. The latex is further called latex C.

According to the invention, a mixture consisting of 48 wt. Latex A and 52 parts by weight TIn. Latex B = Mixture AB, made.

Not according to the invention was a mixture of AC, consisting of 48 parts by weight of TIn. Latex A and 52 parts by weight TIn. Latex C, made.

A mechanically consolidated needled felt based on propylene was fibers or with the mixtures AB "AC impregnated subsequently squeezed between 2 Poulardwalzen and dried at 120 ⁰ C. Thereafter, the Florerholung and dimensional stability was measured.

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Results FROM Needle felt pile dimensional stability AG recreation (%) (%) 98 ίο With mixture 89 -1.4 With mixture

The blend AB treated needled felt had a soft tack-free surface and a textural character, while the blend treated with AO had a hard surface that almost lost its textural character.

Further, a mixture was prepared as follows: 45 parts by weight. Latex A and 55 parts by weight. Latex Bj this latex mixture according to the invention = mixture AB2.

Not according to the invention, a mixture of latex A and C was prepared so that the total butediene content was equal to that in mixture AB2 and from 49 wt. Latex A and 51 parts by weight TIn. Latex C consisted = mixture AG2.

Results

Needlefelt Pile - Dimensional Stability Recovery (%) (%)

With mixture AB 2.

(According to the invention) 98 i 0

With mixture AC 2

(not according to the invention) 84-1.7

It follows surprisingly that there is also a greater production flexibility of the mixtures according to the invention and the processor hereby a more stable production with the same end properties

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achieved, despite deviations of the mixing amount of the 2 different latices.

All mixtures were after 10 min. Shear stress coagulate and thus mechanically stable, but had formed during prolonged driving period of more than 48 h in the mixtures not inventive coatings on the rollers.

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Claims (1)

- 11 - 216270 In duction assert . Process for the preparation of an impregnating latex for needlefelt, in particular for needled felt of synthetic fibers, based on an oarboxylated butadiene latex and a butadiene latex without f uncti.onelle groups in the polymer molecule, characterized in that a mixture is prepared a) 45 to 55 % of Oarboxyllatex with 40 to 48 ¹ weight TIn. Butadiene, 35 to 59 parts by weight. Styrene and / or acrylonitrile and 1 to 5 Gewol-Tln. one or more vinylidenecarboxylic acids in the polymer and b) 45 to 55 7 ° ^d ® ^s Butadienlatex without functional groups with 48 to 55 parts by weight of TIn. Butadiene and 45 to 55 parts by weight. Styrene in the polymer.