GB2135680A - A polymer fibre, a composition from which if may be spun and a method for producing the composition - Google Patents

Abstract

A fibre whose properties approximate to those of natural wool comprises at least one synthetic polymer such as polyacrylonitrile or polyvinylchloride and from 3-50 parts, per hundred of synthetic polymer (by weight), of finely-divided particles of lamellar or membranous structures derived from micro-organisms such as bacteria, yeasts, microalgae etc. Compositions comprising dispersions of such particles in polymer solutions, and methods of making up such compositions, are also described.

Description

SPECIFICATION A polymer fibre, a composition from which it may be spun, and a method for producing the composition This invention pertains to fibre manufacture and, more specifically, to an improved fibre comprising both synthetic and natural organic polymers. The invention also relates to a composition from which such a fibre may be spun, and to a method for producing this fibre by such spinning. The invention will be found particularly useful in the manufacture of fibres whose properties approximate to those of natural wool.

Natural wool has a valuable combination of properties not possessed by other fibres. The problems of replacing wool by other fibres, whether artificial or synthetic, are still unresolved.

Production of artificial protein fibres has not been achieved on a large scale due to the scarcity and lack of uniformity of the starting materials and in any case such fibres possess only modest physico-mechanical and performance characteristics. Articles manufactured purely from synthetic polymer can be uncomfortable and unhygienic.

A recent proposal for a wool replacement fibre is a fibre comprising industrial synthetic polymers and biopolymers, the latter being nowadays available from microbiological industry in quantity and with stable characteristics.

Thus, it is known that simple soluble biopolymers obtained from yeast are capable of imparting a number of valuable properties to polyacrylonitri le based fibres.

USSR Author's certificate No. 522289 (Int.

Cl.D 01 F1/10 issued May 15, 1973) teaches a mixture of simple soluble biopolymers and lipids.

The constituents, expressed in parts by weight are nucleic acids 6-1 2, polysaccharides 30-50, lipids 0.5-2. Protein makes up the remainder.

This document also discloses a composition containing this mixture from which a fibre may be spun. The composition comprises (a) 12 parts by weight of a mixture of dissolved products of yeast degradation (primarily the simple polymers and lipids) and polyacrylonitrile, in a weight ratio of 5:95, and (b) 3.8 parts by weight of an aqueous alcoholic solution of sodium thiocyanate, saturated at 250C, with water to alcohol ratio of the solute 3:1. The composition is made by decomposing yeast biomass down to the simple soluble polymer by mixing dry yeast with polyacrylonitrile, adding the aqueous alcoholic solution of sodium thiocyanate and heating the suspension at the above-mentioned component ratios to boiling point until complete dissolution.

The composition is then cooled, deaerated and spun into a precipitation bath containing a 12% aqueous solution of sodium chloride. The fibre is stretched by 1500% in direct steam medium, washed and dried. The resultant product fibre contains 4-5 parts by weight of the products derived from yeast degradation (mostly the mixture of protein, nucleic acids, polysaccharides and lipids) for every 100 parts by weight of polyacrylonitrile.

The resulting fibre has an increased hygroscopic capacity, conductance and dyeability. Its physico-mechanical properties, however, are relatively low; thus, its strength is 14.5 gf/tex and elongation 9.6%, as compared to 24-28 gf/tex and 2330%, respectively, for polyacrylonitrile fibres. Moreover, the resultant fibre lacks the matt surface, softness of feel and the filling of natural wool. When undyed, the material has a yellowish tinge and its dye adsorption levei is relatively low. The fibre is also prone to deterioration in use; due to their solubility the biopolymers contained in the fibre mass become partially lost after repeated washing thereby bringing down the hygroscopic capacity and the conductance, which are both linked with the biopolymer content.Such fibre is moreover expensive due to inefficient take-up of the biomass and the extra costs of using such a complex manufacturing technique.

The composition from which the fibre of this prior art is spun includes a considerable amount of low-molecular-weight substance formed on the degradation of the yeast, and moreover includes a flammable alcohol, which complicates subsequent production stages. During spinning these low molecular-weight substances and alcohol are excluded from the fibre and arrive in the precipitation bath. This gives a less efficient regeneration and increased effluent pollution.

Furthermore, the flammable alcohol is a fire hazard requiring special precautions, especially since rapid continued heating is required to dissolve the degradation products. The presence of yeast dyestuffs yellows the undyed fibre. Extra costs follow from fire-safety precautions, loss of the low-molecular-weight part of the biomass, less efficient regeneration of the precipitation bath, and the increased pollution.

This invention sets out to provide a fibre with certain of the useful and stable characteristics associated with natural wool (hygroscopic capacity, conductance, dyeability, matt surface, softness of feel and bulking) and with synthetic fibres (strength and elongation). It further aims to provide a composition from which such fibre may be spun without undue complication of manufacturing technique.

In one aspect the invention provides a fibre comprising at least one synthetic polymer having uniformly distributed throughout its structure finely divided particles of at least one biopolymer constituted by the lamellar or membranous structure of micro-organisms, in amounts ranging from 3 to 50 parts by weight of biopolymer per 100 parts by weight of synthetic polymer.

Any synthetic polymer spinnable from solution may be used e.g. polyacrylonitrile or polyvinyl chloride.

The "lamellar structures" of micro-organisms, also referred to herein as "membranous structures" are generally constituted by the membranes of the cell wall and/or the membranes surrounding and defining internal features of the cell.

These lamellar sturctures are essentially conjugated biopolymers. They are available from microbiological industry in the form of spheres, ellipses, rods, threads and such like configurations having a diameter of from 0.2 to 25 Mm and a length of 0.25 to 30 ,um i.e. visible in the optical microscope. The starting raw material for their manufacture is usually various species of microorganisms, e.g. bacterial, Actinomycetales, yeast, fungi or microalgae. The particles are purified of substances soluble in the solvents normally used for synthetic polymers and substances soluble in solutions of detergent agents. They consist predominantly (up to at least 55%) of residual amino acids and sugars with substantial proportion of triple bonds.They may also contain up to 45% of other compounds, for example, residual nucleotides, lipids and mineral substances firmly combined with the principal components. The lamellar structures have a considerable mechanical strength and elasticity so that in the fibre their initial properties, or their size and shape, do not alter. Their hydrophilic capacity and conductance are on a par with those of proteins, nucleic acids and polysaccharides, while their ability to bond dyes is greater by 3040%. They also possess low transparency and good whiteness. They can be evenly distributed even in high proportions and can be fixed securely into synthetic polymers without impairing their physico-mechanical characteristics. The lamellar or membranous structure particles used are known in the food industry, broadly defined.

However, they are not those used for human consumption, and even when fed to livestock are less nutritious than proteins and micro-organism biomass; their cost therefore is relatively low.

The presence of the lamellar or membranous structures in the fibre therefore improves hydrophilic capacity or conductance and gives good affinity for various types of dyestuffs.

Moreover, since the particles have a low transparency and good elasticity when incorporated into the chemical fibre, they impart a matt surface, softness of feel and bulking to the fibre. Resistance of the lamellar or membranous structures to the action of detergent solutions is a major mechanism ensuring stable behaviour of the fibre in use.

As stated above, for every 100 parts by weight of the synthetic polymer there are from 3 to 50 parts by weight of the lamellar or membranous structures in the fibre. We have found that smaller levels of these particles do not afford the desired improvement in hygroscopic capacity, conductance, good affinity for dyes, matt surface, softness of feel and bulking of the fibre, and that higher amounts thereof greatly impair the resultant fibre's physico-mechanical characteristics. In this latter respect it is preferred that at least 95% of the lamellaror membranous structure particles have a diameter less than 1/5 that of the fibre filament, and the rest fall within a range of from 1/5 to 2/5 the diameter of the fibre filament.

In another aspect the invention provides a composition which may be spun into such a fibre comprising a uniform suspension of the lamellar or membranous structure particles in a solution of the synthetic polymer, in a weight ratio of from 3 to 50 parts by weight of such particles per 100 parts by weight of the synthetic polymer.

This composition is improved over the prior art by using the lamellar or membranous structures instead of the simple biopolymers and free lipids, which are partially leached out in the spinning process and repeated subsequent washings. The composition of the present invention also does not contain the flammable alcohol, lowmolecular-weight substances or white dyestuffs which contaminate the precipitation bath.

Preferably, the composition contains lamellar or fibrous structures whose solubility in solvents of synthetic polymers or in solutions of detergents does not exceed 5%. Any greater proportion of substances removed by leaching may complicate the process by contamination of the precipitation bath and diminish the fibre quality in use because of diminution in its desired biopolymer content.

The polymer solvent is preferably selected from aqueous salt solutions or organic solvents, for example, a concentrated solution of sodium thiocyanate (for polyacrylonitrile) or dimethylformamide (for polyvinylchloride). It is undesirable, however, to introduce into the composition any significant amount of substances capable of destroying the biopolymers, for example, inorganic acids or hydroxides of alkali metals.

In a third aspect of the invention provides a method for producing such a composition comprising the steps of dissolving synthetic polymer in, or forming synthetic polymer in situ in, the solvent, adding thereto the lamellar or membranous particles to constitute from 3 to 50 parts by weight per 100 parts by weight of synthetic polymer, and mixing to a uniform suspension.

This method for producing the composition for which the fibre can be spun has reduced the number of its constituent steps and is a simple process which obtains a suspension by mechanical agitation, instead of the complex and dangerous prior art process of dissolving the biomass by means of rapid and continued heating of a highly flammable mixture.

The method decreases the likelihood of contamination of the components of the precipitation bath, and its effluent problem.

It is preferred, when preparing the composition, to prepare a fine suspension of the lamellar or membranous structure particles in the solution of the synthetic polymer and to ensure mixing of all constituents in a known mixer provided with an impeller agitator operated e.g. at a rate of 30 rpm. At the start of mixing the synthetic polymer and the lamellar or membranous structure particles may be added in dry form. Alternatively, the synthetic polymer may be added in the form of a solution. The biopolymer may be added in the form of a suspension in the same solvent as used for the synthetic polymer. The solution of the synthetic polymer may be obtained by dissolving the dry polymer or by polymerization of monomers in situ.

The fibre is spun, by extrusion of the composition through a spinneret, most commonly into diluted solutions of the same solvent as used for the synthetic polymer. The spun filaments may be stretched and, if necessary, passed through a steam chamber, washed out and dried.

The invention is further described with reference to the following illustrative Examples.

EXAMPLE 1.

The starting materials were: (a) a polyacrylonitrile obtained by polymerization of a monomer mixture of acrylonitrile, methylacrylate and itaconic acid in proportions of 92.5, 6.0 and 1.5 respectively, (b) yeast lamellar structures in the form of eliipsoidal particles ranging from 4x5 Mm to 7 x9 ,um and containing 85.1% by weight of residual amino acids and sugars, and (c) a 51.5% by weight aqueous solution of sodium thiocyanate.

100 parts by weight of the polyacrylonitrile (a) were dissolved in 688 parts by weight of aqueous solvent (c). 3 parts by weight of yeast lamellar structures (b) were suspended in 12 parts by weight of aqueous solvent (c). The solution and the suspension were placed in an impeller vessel at 200C and agitated at 30 rpm while the particles were evenly distributed.

The resulting composition, containing 100 parts by weight of the polyacrylonitrile (a), 700 parts by weight of the aqueous solution (c) and 3 parts by weight of the yeast lamellar structures had an operating viscosity of 300 p and a specific viscosity of 1.05. It was de-aerated and extruded through a spinneret (100/0.08) into an 11% by weight aqueous solution of sodium thiocyanate at 1 00C and at a negative spinneret draft of 60%.

The filaments obtained were drawn to 1 50- 200% of their length at 250C, and subsequently stretched further, in a steam chamber, to an overall draw ratio of 700750%.

A soft, bulky, fibre of matt surface appearance with ellipsoidal yeast lamellar structures distributed uniformly throughout was produced.

The fibre thus obtained had the following characteristics: Fineness of yarn 0.330 tex strength 27.4 gh/tex elongation 29.0% relative loop tenacity 30% hydroscopic capacity at 60% relative humidity 1.2% hydroscopic capacity at 95% relative humidity 3.0% electric resistance 5x101 Q static charge 0.5 C whiteness 90% adsorption of acid scarlet dye by dry fibre 0.3% EXAMPLE 2.

The starting materials were: (a) the polyacrylonitrile as in Example 1, (b) the lamellar structures of bacteria in the form of cylindrical particles having a diameter of from 0.1 to 0.2 ym and a length of 0.5 to 2.0,us, and containing 89.5% by weight of residual amino acid and sugars, and (c) the aqueous thiocyanate solution of Example 1.

The procedure applied to make up the composition was described in Example 1, except that 100 parts of polyacrylonitrile were dissolved in 500 parts of solvent (c) and 50 parts of bacterial lamellar structures were suspended in 200 parts of solvent (c). This gave a composition of weight ratio 100:700:50 [(a): (b): (c)] of operating viscosity 280 p and specific viscosity 11 Spinning of the de-aerated composition, through an identical spinneret, was carried out into 3% by weight aqueous sodium thiocyanate at 1 00C. Initial stretch in a steam chamber was to an overall draw ratio of 900--9 500C.

A soft bulky fibre, with a matt surface appearance and even distribution of lamellar structures, was produced.

The fibre thus obtained had the following characteristics: fineness of yarn 0.352 tex strength 25 gf/tex elongation 24% relative loop tenacity 20% hygroscopic capacity at 60% relative humidity 3.8% static charge -0.2 C whiteness 85% adsorption of acid scarlet dye by dry fibre 2.0% EXAMPLE 3.

The starting materials were: (a) polyvinylchloride (b) the lamellar structures of bacteria, as in Example 2, and (c) dimethylformamide.

100 parts by weight of polyvinylchloride (a), 25 parts by weight of lameilar structures (b) 525 parts by weight of dimethylformamide (c) were mixed at 800C at an impeller rate of 30 rpm, until the polyvinylchloride (a) had completely dissolved and the lamellar structures were uniformly distributed.

The resulting 100:525:25 composition was de-aerated and spun through the 100/0.08 spinneret into a water: dimethylformamide bath (15:85). The filaments were stretched to draw ratio of 450% of the initial length, washed, and again stretched to 200% of their previous length.

The fibre thus obtained has the following characteristics: fineness of yarn 0.1 6 tex strength 26.0 gf/tex elongation 21.0% relative loop tenacity 53% hygroscopic capacity at 60% relative humidity 2.3% electric resistance 5x 109Q adsorption of acid scarlet dye by dry fibre 0.5%.

It will be apparent from the above Examples that the fibre so produced is of improved utility, and the method of producing the fibre is straightforward.

Claims (14)

1. A fibre comprising at least one synthetic polymer having uniformly distributed throughout its structure finely divided particles of at least one biopolymer constituted by the lamellar or membranous structures of micro-organisms, in amounts ranging from 3 to 50 parts by weight of biopolymer per 100 parts by weight of synthetic polymer.

2. Afibre as claimed in claim 1 in which the synthetic polymer is polyacrylonitrile.

3. A fibre as claimed in claim 1 in which the synthetic polymer is polyvinylchloride.

4. A fibre as claimed in claim 1,2 or 3.in which the lamellar or membranous structures are spheres of diameter 0.2-25 microns, or are ellipses, rod or threads of transverse diameter 0.2 to 25 microns and maximum length 0.25 to 30 microns.

5. A fibre as claimed in any one preceding claim in which the lamellar or membranous structures are derived from bacteria, Actinomycetales, yeast, fungi, or microalgae.

6. A fibre as claimed in any one preceding claim in which at least 95% by weight of the lamellar or membranous structures have a diameter of less than one-fifth of the fibre diameter and the remainder of the said lamellar or membranous structure particles have a diameter between one-fifth and two-fifths of the fibre diameter.

7. A fibre as claimed in claim 1 and substantially as herein described with reference to any Example.

8. A composition which may be spun into a fibre as claimed in any one preceding claim comprising a uniform suspension of the lamellar or membranous structure particles in a solution of the synthetic polymer, in a weight ratio of from 3 to 50 parts by weight of such particles per 100 parts by weight of the synthetic polymer.

9. A composition as claimed in claim 8 in which the synthetic polymer is acrylonitrile and the solvent is sodium thiocyanate.

10. A composition as claimed in claim 8 in which the synthetic polymer is polyvinylchloride and the solvent is dimethylformamide.

11. A composition as claimed in claim 8, 9, or 10 in which the lamellar or membranous structure particles are less than 5% by weight soluble in either the synthetic polymer solvent or an aqueous detergent solution.

12. A composition as claimed in claim 7 and substantially as herein described with reference to any Example.

1 3. A method for producing the composition as claimed in any one of claims 8 to 12, comprising the steps of dissolving synthetic polymer in, or forming synthetic polymer in situ in, the solvent, adding thereto the lamellar or membranous particles to constitute from 3 to 50 parts by weight per 100 parts by weight of synthetic polymer, and mixing to a uniform suspension.

14. A method as claimed in claim 13 in which the said particles are added as a uniform suspension in a separate body of the same solvent.

1 5. A method as claimed in claim 13 and substantially as herein described with reference to any Example.