NO151793B - HEAVY FLAMMABLE Melt-spun POLYPROPYLENE FIBER AND A PROCEDURE FOR THEIR PREPARATION - Google Patents

Description

The invention relates to highly inflammable melt spun yarns

polypropylene fibers and a method for their production.

Polypropylene fibers that were produced in the melt spinning process have, compared to other synthetic fibers, remarkably good properties with regard to firmness and strength, which make them suitable in the form of textile raft structures such as weaves or fleeces for use as raw material for home textile styles or needle felt floor coverings, as well as for weaves or flor for technical purposes. In contrast to these good mechanical properties, the relatively good flammability of the fibers stands as a disadvantage.

As you know, in recent years with the increasing use of synthetic fibers or also layered materials due to their more or less good combustibility, the number of fires has increased greatly in residential areas or places of entertainment, causing great damage to valuables and also human lives have been lost. As a result, chemical compounds have increasingly been developed, with which natural and artificial fibers can be impregnated flame retardant. (See e.g. the journal "Textilpraxis internat." 1975, H.12, 1685 ff).

According to DOS 27 43 127, it is proposed to make fibers or fabrics of polyesters, polyamides or polyacrylonitrile flame resistant by applying an aqueous dispersion of bromine-containing, aromatic, aliphatic or cycloaliphatic compounds, which also contain a monomeric or polymeric organic compound of tetravalent tin, by spraying, printing, especially by drawing up and subsequent fixation by treatment at 130-220°C. The amount of the bromine compound, which is preferably hexabromocyclododecane, is thereby selected so that the amount of bromine after the heat treatment referred to the treated material amounts to 1 to 8% by weight. The amount of organic tin compound should amount to 5-20% by weight of the bromine compound used. Finally, the addition of a dispersant and/or a protective colloid to the aqueous bath is also recommended to facilitate application. All these substances produce a relatively high coating on the surface of the fibres, which entails a tendency for them to discolour, which must be counteracted by the addition of the organic tin compound.

Apart from the fact that such a surface coating cannot be maintained without affecting grip, as well as other properties of the shape, this coating is also subject to wear and tear during use and cleaning, which must lead to a reduction in the flame retardant properties.

For polypropylene fibres, which are known to have hydrophobic properties, such an impregnation is hardly suitable.

An object of the present invention is to provide a polypropylene fiber which is not made flame resistant by impregnation, but by incorporating a flame protection agent into the plastic. Against this, however, was that with this addition neither the processing technical properties nor firmness, grip and finally color should not suffer. gone-

from this point of view, there was a requirement that the incorporated flame retardant should not exert any corrosive effect on spinning devices such as extruders, spinning pumps and spinning plates, and despite the relatively high temperatures, there should be as little odor development as possible.

In AT-PS 331 505, the addition to polypropylene mixtures of a flame retardant system consisting of 2-7% by weight 1,3,5-tris-(2,3-dibromopropyl)-2,4,6-trioxohexahydro-triazine and 0.5-2% by weight antimony trioxide.

This flame retardant system primarily has the advantage that the brominated triazine compound, which is highly volatile, does not "sweat out" from the polypropylene and that the mixture remains thermo-stable up to approx. 220°C, and the flame retardant active substance does not, like other polybromine compounds, tend to hydrobromine decomposition, discoloration of the product, increase of the melting index of the polymer melt and lastly does not result in strong corrosion on the extruder, etc.

At higher temperatures of 240-300°C, as is necessary for the melt-spinning process of polypropylene, on the other hand, a partial decomposition also occurs with this flame retardant system during bromine-hydrogen decomposition, which led to intolerable corrosion of equipment and discoloration of the fibers for fiber production.

It has now surprisingly found that a certain group

of organic tin compounds, which have at least two alkyl groups, causes a stabilization of the flame retardant effect, bridging

added triazine compound, so that the polypropylene mixture containing this compound can be subjected to the melt spinning process without difficulty, as despite the necessary high temperatures, no corrosion can be seen on the equipment or an unpleasant odor load, and the physical properties of the fibers are satisfactory. Above all, it was surprising that the addition of this tin compound, in contrast to other compounds having a stabilizing effect on the halogen compound, does not affect the flame retardant effect of the brominated triazine compound.

The object of the invention is consequently a highly inflammable melt-spun propylene fiber with an ethylene content of from 0 to a maximum of 10% by weight, the fibers being characterized by being evenly distributed within the fiber. 0.5 to 10% by weight 1,3,5-tris-(2,3-dibromopropyl)-2,4,6-trioxo-hexahydrotriazine and 0.15 to 3.5% by weight antimony trioxide, as well as per mol of the triazine compound 0.05-1.5 mol of an organotin compound with the general formula:

in which

R1 and R2 which may be the same or different, each means one

alkyl or cycloalkyl residue and

X and Y which may be the same or different, each means an alkyl or cycloalkyl residue, the residue of an organic acid which may optionally contain a further esterified carboxyl group, the residue of an inorganic acid, a thioalkyl group, which may optionally have one esterified with aliphatic alcohols carboxyl group, or

X and Y together mean oxygen, the residue of a dibasic inorganic or organic acid, or a residue of the formula -S-(CH2 0) 'n-COO-, where n is defined as the numbers 1 or 2,

and possibly also known in and of themselves, lubricants, pigments and/or stabilizers.

The alkyl radicals R 1 and R 2 can here preferably have 3-10 carbon atoms. If and/or Y is also alkyl, those with 3-10 C atoms are also preferred here. Examples of effective compounds with formula I include: Dibutyltin oxide, dioctyltinoxide, tetra-n-octyltin, di-n-butyltin dilaureate, di-n-octyltin dilaureate, di-n-octyltin phosphite, dioctyltin maleinate, dibutyltin maleinate, triphenyltin acetate, di-n-octyltin di-(thioglycolic acid n-octyl ester), dibutyltin di-(thioglycolic acid octyl ester), dioctyltin di-(maleate methyl ester), dibutyltin dimaleate methyl ester, dibutyltin dibenzoate, dibutyltin phthalate and dioctyltin thioglycolate, while, for example, other tin compounds such as monooctyl tin oxide or calcium oxide resp. -hydroxide does indeed have an excellent stabilizing effect, but at the same time the flame retardant effect of the brominated wood azine compound used according to the invention is cancelled.

Particularly preferred are such tin compounds of formula I, in which X and Y each mean a maleic acid ester residue or X and Y together are a maleic acid residue.

It is very advantageous that the amount of the brominated triazine compound in the fibers already at low additions unfolds its full effect so that the fiber properties are practically not affected thereby. The best combination of flame retardant effect with the least impact on the fibers' properties is achieved with a content of triazine compound in the fibers of 1-3% by weight, the amount of synergist then preferably remaining below 1% by weight. The preferred amount of tin compound of formula I then amounts to 0.1 to 0.3 mol per moles of triazine compound.

A further object of the present invention is a method for producing the highly inflammable fibers according to the invention, the method being characterized by a-t a mixture of polypropylene with an ethylene content of from 0 to a maximum of 10% by weight with a content of from 0.5 to 10% by weight % 1,3,5-tris-(2,3-dibromopropyl)-2,4,6-trioxo-hexahydrotriazine and 0.15-3.5% by weight

^ antimony trioxide, as well as per mol of the triazine compound 0.05-1.5 mol of the organotin compound with formula I, as well as possibly lubricants, pigments and/or stabilizers are subjected to a melt-spinning process,

Thereby, the finished polypropylene mixture such as e.g. available in granulated form is melted and spun. However, it is also possible to add the flame-retardant acting system first in the extruder, as e.g. the triazine compound, Sb2C>2 and the tin compound of formula I are added via a side extruder to the melted polypropylene. These additives can thus be handled as pure substances or concentrates (master batch). As a binder for the latter, either polypropylene or other plastics compatible with polypropylene, such as e.g. other polyolefins.

The polypropylene melts equipped with a flame retardant in this way can be spun or preprocess into an endless fiber pile in the short-spinning process, which is characterized by low take-off speeds (5-50 m/min.) as well as in normal melt-spinning processes, which have typical take-off speeds from 100-1000 m/min. as also in so-called fast-spinning methods (draw-off speed over 1000 m/min), as well as in so-called "jet-spinning" at extreme speeds of 4,000 m/min.

The fibers produced in this way can be stretched in the same way as non-flame-retardant finished polypropylene fibers,

mug, further processed staple fibers and equip with normal avivage.

Pigments, antioxidants, light protection agents and lubricants, as well as radical-forming peroxides in the form of pure substances or concentrates, can also be added to the flame-retardant treated polypropylene melt before spinning without loss of effectiveness. The latter effect is molecular breakdown (degradation) during the reduction of the molecular weight and can, with the help of the resulting equalization of the molecular weight, have a beneficial effect on the fiber properties. Surprisingly, the flame retardant effect of the additive according to the invention is not affected by this treatment.

Examination of difficult flammability of the fibres

according to the invention takes place in small firing samples according to DIN 53438.

The burning test is carried out in accordance with DIN standards with textile raft structures, using the following assessment criteria: a) The burned-out length is less than 150 mm, the test extinguishes yourself. Class K-^. b) The flame tip of the burning specimen achieves the measurement

mark of 150 mm within 20 or more seconds. Class K2.

c) The flame tip of the burning specimen reaches the measurement mark of 150 mm in less than 20 seconds. Class

K3. The sample is flammable.

The effect of the thermal decomposition of the flame retardant, the consequent discolouration of the polypropylene melt, as well as the corrosion associated with the decomposition can be easily investigated by means of multiple extrusions at high temperatures using a laboratory extruder.

Extruder data:

Screw: 19.1 mm diameter, screw length 20 D, polyolefin screw,

3 stages, compression ratio 1:4

Round nozzle: 5 mm diameter, water bath, string granulation device.

For all experiments, the screw speed was kept constant at 100 rpm, the mass temperature indications refer to the temperature measurement at the screw tip.

The effect of the cleavage in HBr corrosion is determined according to the following method: The granule sample of 15 g weight formed after extrusion, cooling and granulation of the string is pressed at 230°C in a press in contact with a degreased and polished to a high gloss steel plate for a duration in 7 minutes to a plate of 70 x 70 x 2 mm. After cooling, the polypropylene plate is carefully detached from the steel, the steel plate is then stored for 24 hours at 23°C and 100% relative humidity and is then evaluated as follows:

Number 0: completely free of corrosion

Number 1: light rust formation (seen by wiping with a clean

dropsy and discoloration of the water)

Number 2: Superficially covered evenly with rust

Number 3: Surface covered with strong rust formation.

The multiple extrusion trials took place both at 250°C and also at 280°C from granulated product. Crushing of the additives took place under gentle conditions at a mass temperature of 210°C. It should be mentioned that for the examination of the thermal decomposition of the flame retardant, a polypropylene with a high molecular weight was deliberately chosen in order to be able to carry out the multiple extrusions carried out at the high test temperatures (250-280°C) with intermediate granulation each time. It could also be established in these tests that the molecular weight size of the polypropylene has no effect on the HBr separation from the flame retardant.

In the following examples, the production and properties of the fibers according to the invention are explained in more detail.

Example 1-10

A polypropylene blend based on polypropylene with a melt index of 12 of the following composition: Calcium stearate 0.2% by weight, 2,6-di-tert.butyl-p-cresol 0.1% by weight, penta-erythrityl-tetratris-/3- (3,5-di-tert-butyl-4-hydroxyphenyl)-propionate 0.1% by weight, 1,3,5-tris-(2,3-dibromopropyl)-2,4,6-trioxohexahydrotriazine 3,1 % by weight, antimony trioxide 1.0% by weight, the organic tin compound specified in the table 1.0% by weight or 2.0% by weight and polypropylene 94.2% by weight are spun on a melt spinning plant with a screw diameter of 25 mm and 24 D length at a mass temperature of 255°C, a screw speed of 74 rpm. and a withdrawal speed of 470 m/min. to fibers with a total titer of 346 tex at 68 capillaries„ The drawing of the primary threads produced in this way took place on a drawing machine at a temperature of 130°C and a draw ratio of 1:3. The final titer of the threads formed was 1 .15 tex, the titres of the single capillaries at 1.7 tex. The properties of the threads thus formed are listed in table 1.

Example 11

The polypropylene mixture, which was processed according to Ex. 1-7 and 10 to fibers are subjected to the burning test according to DIN 53438 (small burning test); the fibers were spun into a yarn of 230 tex/136 capillaries and then processed on a circular knitting machine into a fabric with a basis weight of 530 g/m^. The investigation of this raft structure took place in small fire samples by edge flame treatment. The results are listed in Table 2.

Example 12

Mixtures that were processed into fibers according to

Ex. 1,2,4,8,9 and 10 were subjected to the corrosion test. As a blank sample, a mixture containing the same components as the mixture according to Ex. 1-10, to which no tin compound of formula I was added. The results are listed in Table 3.

Claims (2)

1. Highly flammable melt-spun polypropylene fibers with an ethylene content of 0 to a maximum of 10% by weight, characterized in that they contain 0.5 to 10% by weight 1,3,5-tris-(2,3-dibromopropyl)- 2,4,6-trioxo-hexahydrotriazine and 0.15 to 3.5% by weight Sb2O3 as well as per mol of the triazine compound 0.05 to 1.5 mol of an organotin compound of the general formula: in which R-^ and R2 which may be the same or different each means an alkyl or cycloalkyl residue and X and Y which may be the same or different, each means an alkyl or cycloalkyl residue, the residue of an organic acid which may optionally contain a further esterified carboxyl group, the residue of an inorganic acid, a thioalkyl group which may optionally have a carboxyl group esterified with aliphatic alcohols, or X and Y together mean oxygen, the residue of a dibasic, inorganic or organic acid, or a residue of the formula -S-(CH2) n-C00-, in which n is 1 or 2, and possibly also per se known lubricants, pigments and/or stabilizers. 2. Heavily inflammable polypropylene fibers according to claim 1, characterized in that they contain, as a tin compound of formula I, those in which X and Y each mean a maleic acid alkyl ester residue or together a maleic acid residue. 3> Heavily inflammable polypropylene fibers according to claims 1 and 2, characterized in that the content of the triazine compound amounts to 1-3% by weight. 4- Heavily inflammable polypropylene fibers according to claim 3, characterized in that the amount of Sb2O3 amounts to 0.3-1% by weight. 5. Heavily inflammable polypropylene fibers according to claims 1-4, characterized in that the amount of the tin compound with formula I amounts to 0.1-0.3 mol per moles of triazine compound. 6o Process for producing the highly flammable polypropylene fibers according to claims 1-5, characterized in that a mixture of polypropylene with an ethylene content of from 0 to a maximum of 10% by weight, which contains 0.5-10% by weight of 1,3,5-tri s-(2,3-dibromopropyl)-2,4,6-trioxo-hexahydrotriazine and 0.15-3.5% by weight antimony trioxide, as well as per mol of the triazine compound 0.05-1.5 mol of an organotin compound of the general formula in which R-^ and R2 each means an alkyl or cycloalkyl residue and X and Y each means an alkyl or cycloalkyl residue, the residue of an organic acid, which may optionally contain a further esterified carboxyl group, the residue of an inorganic acid, a thioalkyl group which optionally can have a carboxyl group esterified with aliphatic alcohols or X and Y together mean oxygen, the residue of a dibasic, inorganic or organic acid or a residue of the formula -S-(CH2)n~COO-, where n is defined as the number 1 or 2 and possibly also lubricants, pigments and/or stabilizers are subjected to a melt-spinning process. 7. Process according to claim 6, characterized in that polypropylene is melted and then mixed with a concentrate of the triazine compound, Sb^^ and the tin compound of formula I, in which polypropylene or other polyolefins are used as binders and where the mixture is fed directly to the spinning diesenc 8 Method according to 6 or 7, characterized in that the finished spinning mixture is subjected to degradation using radical-forming substances before spinning.