DE3249335C2 - - Google Patents

Description

The present invention relates to a process for the preparation of fire-protected mixed fibers of cellulose and chlorine-containing polymers.

Cellulosic fibers, such as cotton and viscose, are as such easily inflammable and fast burning.

The flammability of textiles, in particular the extinguishing properties, can by the corresponding LOI value (Limiting Oxygen Index). In the process is made from a mixture of oxygen and nitrogen the smallest oxygen content determines the one Material needed to burn. Is the LOI value significantly above the oxygen content of the air (21%), clears the fire itself. The following table shows LOI Values for different types of fibers (L. Pekkala, Tekstiililehti No. 3, 1973):

fiber LOI polyacrylonitrile 18.2 cotton 18.4 Cellulose triacetate 18.4 Cellulose diacetate 18.6 viscose 19.7 polyester 20.6 Wool 25.2 modacrylic 26.8 PVC 37.1 Cotton / Polyester 50/50 18.0

The combustibility of a fiber mixture can not be determine the combustibility of each component,  but the determination should always be based on the mixture respectively.

As a fire retardant for cellulose fibers are phosphorus, chlorine, bromine, antimony, tungsten or boron compounds The fiber is usually used during the Finish be added. One also has bromine-containing organic Phosphorus compounds before spinning the fiber can mix under the viscose.

The best-known fire retardants for cellulose fibers are the following:

1. Ammonium phosphates, sulphate, halides and sodium borates

A disadvantage is the water solubility of these substances. The material loses its fire retardant properties after a wash of water.

2. N-methylol-2 (dimethylphosphonatoyl) -propionamide and Tetrakishydroxymethylphosphonium chloride or sulfate

Disadvantages of these fire retardants are resistant nature the high price of chemicals, a multi-phase fire retardant finish, roughened and stiffened texture of the textile, reduced light and weather resistance. In addition, they generate strong poisons when heated, like phosphines.

3. Chlorinated hydrocarbon / antimony oxide

Disadvantages of this finish, which is exclusively for im Free products intended for use are rough and stiff and airtight nature of the Product. The use of antimony brings problems in Respect for occupational safety.  

4. Tris-dibromopropylphosphate before spinning with viscose mixed (about 15% of the amount of cellulose)

The disadvantage of such "integrated" fire retardants exists in their effect on the crystallization of cellulose, which is a radical deterioration of fiber strength entails. The substance has proved to be mutagenic, and their use is banned in the US.

In the production of viscose fiber can be in the aqueous Cellulose xanthate solution (viscose) no organic Polymers are dissolved together with Cellulose to fiber spun advantageous fire retardant Properties (see Table 1).

It has been suggested (Grinshpan, Kaputskii, Savitskaja, Zhurn, Prikald, Khim., 50, 1977, 702) that u. a. PVC one Cellulose could be added in a mixture of nitrogen tetroxide (N₂O₄) and dimethylformamide (DMF) is dissolved, and that the PVC together with the Cellulose could be precipitated as fiber. The production of cellulose fibers from a N₂O₄ / DMF solution The cellulose has proved to be economically unprofitable proven, and there is no production facility for this Procedure has been established.

Furthermore, it has been proposed (Finnish patent application No. 8 00 963), some chlorine-containing polymers of a di- methylsulfoxide (DMSO) / paraformaldehyde (PF) solution of To add cellulose and the chlorine-containing Polymer together with cellulose as a fiber with a fire resistance of at least 21% (LOI coefficient) precipitate. However, it has turned out that chlorine-containing polymers, the cheapest in terms of price are and contain large amounts of fire-retardant chlorine (like PVC or PVC / PVAc copolymer), small clear, homogeneous Mixture with the cellulose in DMSO / PF solvent  form. This has the disadvantage of causing a fire-retardant effect for those from the above Mixtures of manufactured fibers to achieve the cellulose more of these cheap polymers than chlorine-containing ones Polymers containing the cellulose in DMSO / PF solvent form a clear homogeneous mixture, must be added. This is the advantage that is through the use of cheap polymers as fire retardant Funds could be lost in part. In addition, it has been found that the mechanical properties of the tarnish, Inhomogeneous solutions produced fibers meet the requirements on textile fibers can not do justice.

The invention is based on the object, a method to be distinguished with the improved mixed fibers with a LOI fire resistance of at least 21% cellulose and chlorine-containing Allow polymers to be produced economically.

This object is achieved by the specified in claim 1 Invention solved.

The invention is based on the finding that when using a special, known per se solvent for cellulose, namely a mixture of lithium chloride and dimethylacetamide (DMAC) or lithium chloride and 1-methyl-2-pyrrolidone (DE-OS 30 27 033, US-PS 43 02 252), the cellulose in the solution certain chlorine-containing polymers mixed in mixing ratios can be used when spinning the mixture into fibers produce a product that is substantially superior to the cellulose fibers has improved fire retardant properties.

It has also been stated that although DMAC and 1- Methyl-2-pyrrolidone good solvent for synthetic polymers are, the cellulose solution chlorine-containing polymers only in certain proportions can be added. Otherwise, the mixture gels and does not close Spinning fibers. Table 2 on the next page shows the spinnability of mixtures of cellulose and some polymers of LiCl / DMAC and LiCl / MP solutions.  

In DE-OS 30 27 033 or US-PS 43 02 252 is the possibility mentioned, polyamides, polyesters, polyethers, chitin and Urethane LiCl / DMAC or LiCl / MP solutions of cellulose to mix and pieces formed from the mixtures Produce cellulose base. As shown in Table 2 The results of the experiments are to be seen, are the most often, however, not spinnable, resulting in no fibers with the inventive Process can be produced.

Table 2

Spinnability of the blends of cellulose and some polymers of LiCl / DMAC and LiCl / MP solutions

To produce cellulose-based refractory fibers in the process of the invention LiCl / DMAC or LiCl / MP solution of cellulose mixed polymer of acrylonitrile and Vinylidene chloride (modacrylic), copolymer of acrylonitrile and vinyl chloride (modacrylic) or polyvinyl chloride (PVC), mixed polymer of vinylidene chloride and vinyl chloride (PVDC / PVC)  or copolymer of vinyl chloride and vinyl acetate (PVS / PVAc) added in a mixing ratio in which the resulting Mixture not gelled.

The mixtures according to the invention contain 10-60 percent by weight chlorine-containing polymer or polymers of the total amount of cellulose and chlorine containing polymers in the Solution counted. The chlorine-containing polymer can either directly in the cellulose solution or first in a suitable one organic solvents are dissolved and the resulting Blend then mixed with the cellulose solution become. From the resulting clear, gel-free mixed solution Fibers are made by placing them in a solution is where cellulose and chlorine-containing polymer in Be precipitated fiber form. Obtained by this method one fiber with an LOI value of at least 21% O₂, which gives them much better fire retardant properties has as the mere cellulose fiber.

Compared to the known fire protection method of cellulose fibers the method has the following advantages:

• a) The process gives a product with "integrated" Fire retardant. The mixture is homogeneous over the cross section of the fiber;
• b) the fire retardant dissolves during fiber production not in the spin bath, but is completely with the Cellulose fiber precipitated, there are no chemical losses;
• c) the fire retardants are not water soluble, which means the fire protection of the fiber is resistant and through Washing is not affected;
• d) because the fire retardants are long chain polymers orient themselves in the production of fibers such as cellulose  and do not have such a detrimental effect on the strength properties the fiber like the known ones Fire retardants;
• e) an addition of chlorine-containing polymers by this method to cellulose fiber has no influence on the pleasant texture of the fiber.
• f) with the use of chlorine-containing polymers is no health risk associated with
• g) as a fire retardant can in the process the Cheapest commercially available chlorine-containing polymers, such as PVC and PVC / PVAc copolymer without loss of quality the fiber used.

By the following examples, some advantageous embodiments are intended of the method.

Example 1 Preparation of a cellulose solution with LiCl / DMAC solvent

150 g wet pre-hydrolyzed birch sulphate cellulose (65%) Water) were dissolved in 1000 ml of dimethyl acetate (DMAC) for 24 hours. held. After filtering, the cellulose was as possible pressed dry and additionally for 2 hours with a treated with a new dose of DMAC. Finally, the cellulose became pressed to a dry matter content of 25%. 48.9 g of lithium chloride were dissolved at 60 ° C in 495 g of DMAC. The room-warm LiCl solution was the one with the above treated DMAC treated cellulose added within two hours. The clear, 6% cellulose containing solution was heated to 90 ° C and filtered. The viscosity of the resulting cellulose solution was equal to 42 Pa · s at 23 ° C.  

example 2

Preparation of a Cellulosic Solution with LiCl / MP Solvent 52 g air-dry prehydrolyzed birch sulphate cellulose were activated by placing in 1000 ml of water for 1 hour were held. The dry-pressed cellulose became 3 Kept for hours in 1000 ml of 1-methyl-2-pyrrolidone, after which it is squeezed to a dry matter content of 25% was and treatment with a new solvent dose was repeated. Thereafter, the cellulose was at room temperature in 544 g of lithium chloride / 1-methyl-2-pyrrolidone Solution dissolved with a LiCl content of 9%. The obtained clear, 6% cellulose-containing solution was washed with filtered at a temperature of 90 °. The viscosity of Solution was 48 Pa · s at 23 ° C.

example 3 Production of cellulose / PVC 60/40 mixed fibers

A cellulose solution prepared according to Example 1 173 g of a DMAC solution containing 20% PVC was added contained. The mixed solution was added for one hour Shaken at room temperature. The viscosity of the resulting clear solution of good quality was at 23 ° C equal to 30 Pa · s. The solution was passed through the openings of a Spinneret (⌀ 0.08 mm) placed in the water, and the fiber bundle was increased to 200 mm through the aqueous solution Rolled on which they are washed, scoured and dried has been. The spinning speed was 20 m / min. The manufactured fiber felt soft and warm, and she had sufficient strength for textile use on. The tear strength of the acclimated fiber was equal to 140 mN / tex and that of the wet 60 mN / tex. When LOI value for a web of mixed pulp was found at measurements 24-25% O₂, and it went out by itself in the air. As LOI value for one on corresponding  Way produced pure cellulose pulp resulted 18-19% O₂.

example 4 Production of cellulose / PVC 80/20 mixed fibers

A cellulose solution prepared according to Example 2 6.5 g of PVC powder were added and the mixture 3 Stirred for hours at 50 °. The clear solution was filtered and in a manner described in Example 3 spun into fibers. As LOI value for the resulting Fibrous yielded 22-23% O₂, and he burned at the Air continues very slowly or extinguished. The tear strength for acclimated pulp was equal to 200 mN / tex and for wet 120 mN / tex.

example 5 Preparation of cellulose / vinyl chloride-vinyl acetate copolymer 40/60 mixed fiber materials

A LiCl / 1-methyl-2 prepared according to Example 2 Pyrrolidone solution of cellulose, 78 g of vinyl chloride Vinyl acetate copolymer dissolved in 1-methyl-2-pyrrolidone added. The mixture was added for 2 hours Room temperature shaken, and the clear mixed solution Good quality was described in Example 3 Way to fibers spun. The resulting white Mixed fiber had sufficient strength for use as a textile. The tensile strength was equal to 140 mN / tex for acclimated and 65 mN / tex for wet fiber. On made from the mixed fiber Gespinst extinguished at the Air after removing the flame, and as LOI value for it resulted 27-28% O₂.  

example 6 Preparation of Cellulose / Vinylidene Chloride Vinyl Chloride Mixed polymer 80/20 mixed fibers

A prepared according to Example 1 LiCl / DMAC solution of Cellulose was 13 g of vinylidene chloride-vinyl chloride copolymer added dissolved in 1-methyl-2-pyrrolidone. The clear mixed solution was described in Example 3 Way to fiber spun. As LOI value for the pleasant Feeling fiber gave 23-24% O₂ and she went out of breath in the air.

The strength of the mixed fiber was satisfactory.

example 7 Preparation of Cellulose / Vinylidene Chloride Vinyl Chloride Mixed polymer / modacrylic 70/20/10 mixed fibers

A prepared according to Example 1 LiCl / DMAC solution of Cellulose were dissolved in DMAC 14.9 g vinylidene chloride Mixed vinyl chloride copolymer and 7.4 g Modacrylfaserstoff. The mixing took 2 hours. The resulting clear mixed solution was similar to that described in Example 3 Way to fibers spun. The manufactured Fiber felt soft and had a better one Strength than the fiber cited in Example 6. The Blended fiber faded in the air by itself after removal the flame, and as corresponding LOI value resulted 25-26% O₂.

example 8 Production of cellulose / modacrylic 90/10 blended fibers

A cellulose solution prepared according to Example 1  5.8 g of modacrylic pulp were dissolved in DMAC. The mixed solution was changed to one in Example 3 manner spun to fiber. The pleasant Feeling mixed fiber continued to burn slowly in the air Removing the flame, and as an LOI value for it resulted at Measurements 21-22% O₂. The fiber had good strength.

example 9 Production of cellulose / PVC 60/40 mixed fibers by means of DMSO / PF solvent

83 g of air-dried, pre-hydrolyzed cellulose, 83 g of paraformaldehyde and 1100 g of dimethyl sulfoxide were in a 2-1 container heated to 120 ° C within about 1.5 hours. The resulting clear solution was additionally 2.5 hours kept at 120 ° C to get rid of the excess formaldehyde. The solution was filtered hot, and you became DMSO and 55.3 g of polyvinyl chloride mixed. The mixture was kept at a temperature of 70 ° C for 2 hours shaken. The resulting cloudy mixture was through the openings of a spinneret into an aqueous precipitation bath entered. The fiber bundle was stretched, washed and dried. As LOI value for the finished fiber bundle resulted in 24-25% O₂. The tear strength of the mixed fiber was acclimated equal to 60 mN / tex and wet 15 mN / tex, which strength is insufficient for a textile use.

example 10 Production of Cellulose / PVC-PVAc 40/60 Mixtures in DMSO / PF solvent

A filtered cellulose solution prepared according to Example 9 DMSO and 125 g vinyl chloride-vinyl acetate Mixed polymer added. The mixture turned quickly dark and gelled and was unsuitable for fiber production.

Claims (6)

1. A process for the preparation of fire-resistant mixed fibers of cellulose and chlorine-containing polymers, the fire resistance expressed as LOI value is at least 21% O₂, characterized in that

• a) chlorine-containing polymer, either
  a copolymer (modacrylic) of acrylonitrile and vinylidene chloride
  a copolymer (modacrylic) of acrylonitrile and vinyl chloride / polyvinyl chloride (PVC)
  a mixed polymer (PVDC / PVC) of vinylidene chloride and vinyl chloride
  or a mixed polymer (PVC / PVAc) of vinyl chloride and vinyl acetate
  or their mixture,
  either as such or dissolved in an organic solvent, a lithium chloride / dimethylacetamide or lithium chloride / 1-methyl-2-pyrrolidone solution of cellulose so mixed that at least 10, but at most 60 percent by weight of said chlorine-containing polymer of contains the total amount of cellulose and of the chlorine-containing polymer,
• b) fibers are made from the resulting mixture by placing it in a solution where the mixture of polymers in fiber form is precipitated.

2. Method according to claim 1, characterized in that that the chlorine-containing polymer Polyvinyl chloride is the proportion in the mixture at most 40% of the total amount of PVC and cellulose. 3. Method according to claim 1, characterized that the chlorine-containing polymer a Mixed polymer of vinyl chloride and vinyl acetate, and  used as the solvent lithium chloride / 1-methyl-2-pyrrolidone becomes. 4. Method according to claim 1, characterized in that that the chlorine-containing polymer is a mixed polymer is vinyl chloride and vinyl acetate and its proportion in the solution at most 40% of the total amount of Mixed polymer and cellulose, with lithium chloride / Dimethylacetamide is used as a solvent. 5. Method according to claim 1, characterized in that that the chlorine-containing polymer is a mixed polymer from vinylidene chloride vinyl chloride, and its proportion in the solution at most 40% of the total amount of chlorine-containing polymers and cellulose. 6. The method according to claim 1, characterized that the chlorine-containing polymer modacrylic whose proportion in the solution is 40% of the total of modacrylic and cellulose.