Products from poly(p-phenyleneterephthalamide) with high resistance

 

(57) Abstract:

Products made from poly(p-phenyleneterephthalamide) polymer having a characteristic viscosity from 1.5 to 4 DL/g, the sulfur content in the form of sulfo from 5 to 20 moles per 100 moles of the repeating polymer units and the metal present in the form of oxides of tungsten and oxides of molybdenum in an amount of from 1.0 to 15 wt.%, and the method of its manufacture. These products are resistant to fire at least five times higher than similar products that do not contain metal compounds. Protective clothing made from fibers of the present invention, will be better to preserve the physical integrity of in flames. 2 S. and 9 C.p. f-crystals, 3 tables.

The present invention relates to products of poly(p-phenyleneterephthalamide), which have high fire resistance.

In U.S. patent N 4112016, with a filing date of April 3, 1975, described polyamide fibers with improved flame-retardant properties, such as poly(p-phenyleneterephthalamide), who inoculated certain compounds of phosphorus.

In U.S. patent N 4198494, with a filing date of September 30, 1974, describes a mixture of poly(p-phenyleneterephthalamide) and poly(m-isophthalamide) with uluchsheniya fire resistance of aramid fibers is injected into the fiber organic flame retardants with providing the swelling of the fibers of organic liquids.

The closest analogue in this invention is the product of a poly(p-phenyleneterephthalamide), described in the patent WO N 9420565 made by way of reducing Flammability.

This product polymer has at least 0,5% by weight based on the total weight of the metal, where the metal is present in the form of oxides.

The aim of the present group of inventions is the manufacture of products that they remain stable in the presence of a flame, providing, thus, improved fire protection, protective clothing made from fibers of the present invention, will be better to preserve the physical integrity of in flames.

The present invention provides articles having high resistance, made of poly(p-phenyleneterephthalamide) having a characteristic viscosity from 1.5 to 4 DL/g and containing from 5 to 20 moles of sulfur in the form of sulfo for every 100 moles of recurring units of the polymer and from 0.5 to 15 wt%. metal based on the total weight of the product, where the metal is present in the form of oxides selected from the group including oxides of tungsten and molybdenum, and evenly distributed throughout the product, and these products are resistant to fire, at m the finding also provides a method of making articles from poly(p-phenyleneterephthalamide), having a high resistance, and this method includes the stage of contact is not dried products of poly(p-phenyleneterephthalamide) with an aqueous solution of metal ions selected from the group comprising ions of tungsten and molybdenum ions, in order to enter in the product metal in a quantity sufficient to increase the fire resistance of the product; and drying the product.

Products made from poly(p-phenyleneterephthalamide) (PPF-T), is well-known for their extremely high strength and high modulus. However, in some cases, practical application requires the preservation of strength when exposed to flame. Used herein, the term "product" refers to fibers, fabrics, films, narrow strips, tapes, etc. that have the characteristics and qualities of the present invention. The term "product" for the most part means the fiber, fabric or film, and if there is a mention of the fiber, fabric or film, then these terms are in General included in the term "articles".

Despite the fact that the fibers of the PPF-T are fire-resistant by themselves, it is often desirable to have products from PPF-T, which retain their strength in the presence of a flame, providing, thus, improved fire protection.ity in the flames.

It is established that fibers made from sulfonated PPF-T, having a characteristic viscosity from 1.5 to 4 DL/g and containing as sulfo from 5 to 20 moles of sulfur per 100 mol parts of p-phenyleneterephthalamide (the repeating unit in the polymer chain), have a high resistance in the case where PPF-T, from which the product is made, contains a specific compound of the metal is distributed throughout the product. Indeed, the resistance of the products of the present invention from PPF-T, at least five times greater than the resistance of such products that do not contain metal link.

Under PPF-T mean a homopolymer of poly(p-phenyleneterephthalamide). PPF-T is often polymerization of p-phenylenediamine and terephthaloylchloride. Also get copolymers formed by the addition of small amounts of other diamines, along with p-phenylenediamine or small amounts of other chlorides of dibasic acids along with terephthaloylchloride. As a rule, other diamines and other chlorides of dibasic acids may be used in amounts up to about 10 mol%. based on p-phenylenediamine or terephthaloylchloride, provided that other dia is imerissia. Getting PPF-T is described in U.S. patent N 3869429, 4308374 and 4698414.

When conducting a convenient way of manufacturing fibers of the present invention in practice PPF-T with a high characteristic viscosity (approximately more than 5) is mixed with sulfuric acid of a concentration between 100,2 to 102% in order to provide the desired degree of sulfonation of molecules PPF-So Conditions are carefully controlled so that the molecular weight of PPF-T was reduced to the characteristic viscosity (HV) of from 1.5 to 4 DL/g (the latter is measured on the yarn, made of PPF-T), simultaneously achieving the desired degree of sulfonation.

The degree of sulfonation and the degree of splitting PPF-T are in balance, which is controlled by the concentration of sulfuric acid, the concentration of polymer in sulfuric acid, the dwell time of the polymer in the acid and the temperature of the sulfuric acid in the process.

It is established that for dissolution and sulphonation PPF-T is useful to use sulfuric acid with a concentration from 100,2 to 102%. The concentration of the acid above 103% can cause unacceptably strong splitting of the polymer; at concentrations below 100,2% to achieve the desired degree of sulfonation may require unacceptably Bo is the influence on the degree of sulfonation and the degree of splitting of the polymer. Found that is acceptable temperature in the range of from 75 to 120oC and time from 10 minutes to 2 hours.

Characteristic viscosity, which is determined according to the method described below, is a measure of the molecular weight of the polymer and serves as an indicator of lower molecular weight in the process of sulfonation of the polymer.

Upon receipt of the fibers of the present invention of the spinning solution is usually prepared by dissolving, with the necessary concentration PPF-T in concentrated sulfuric acid. The concentration of polymer in the acid typically ranges from 9 to 15 wt%. and preferably equal to about 12 wt%; the concentration of the acid is equal to approximately 100-102%.

Conditions of sulfonation used in the present invention, lead to the sulphur content in the form of sulfo from 5 to 20 moles per 100 moles of the repeating polymer units. When the sulfur content is below 5 moles fiber, seemingly not able to absorb sufficient amounts of metal. When the sulfur content is higher than 20 mol of polymer invariably is unacceptably low molecular weight.

Fiber of the present invention can be spun using a spinning conditions with an air gap as described in the security fiber of the present invention can be colored by the introduction of pigments or other colorants in the spinning solution. A solution of sulfonated PPF-T can be extruded through a multi-channel mouthpiece for the extrusion of filaments, which has openings with a diameter in the range from about 0.025 to 0,25 mm Quantity, size, shape and configuration of the holes can vary so that you can receive the necessary fiber. Extruded pasta is served in a coagulation bath with a preliminary deletion or without prior passage through coagulase fluid layer. Coagulase fluid layer, if used, is typically air, but you can use another inert gas or liquid, which are not coagulants for extruded pasta. Coagulase fluid layer usually has a thickness of from 0.1 to 10 cm

The coagulating bath is water and can contain up to 80% sulfuric acid. The bath temperature may be very low to -10oC; but it may also lie in the range from about 25 to 80oC or slightly above.

After passing the extruded paste through the coagulating bath and coagulation extruded pasta in swollen under the action of acid and water fibers these fibers are thoroughly washed to remove the acid and neutralizaton water.

After forming fibers of sulfonated having a low characteristic viscosity PPF-T these fibers into non-dried form in contact with an aqueous solution of a compound of the metal to absorb the metal and, because of the presence of this metal, increases the fire resistance of the product. As installed, the number of metals for use in the present invention provides improved fire resistance fibers; however, molybdenum and tungsten, as shown, provide a truly remarkable improvement in this property. Tested other metals, including palladium, vanadium and zirconium, and they, as installed, will also give a higher fire resistance.

Contacting the product with an aqueous solution of metal cations can be carried out after the stage of coagulation spinning process, or an aqueous solution of a compound of the metal may be used directly as a coagulating the fiber liquid in the spinning process.

Can be used any compound of molybdenum or tungsten, which can form a stable aqueous solution. Compounds that promote dissolution of metal compounds may also be added to aqueous solution. Suitable soedineniya, such as phosphorus-tungsten acid, homopolysaccharide, such as ammonium tungstate and sodium tungstate. Can be used any compound of tungsten, if it is soluble in water and does not precipitate during the process. Preferred compounds of tungsten are phosphomevalonate acid and metabolomic ammonium. Preferred compounds of molybdenum are phosphomolybdenum acid.

The concentration of the metal in aqueous solution, the solution temperature and time of contact of the solution and not the dried fiber is not decisive, provided that an effective amount of metal absorbed by the fibre structure. The preferred concentration is measured based on the elemental metal) from more than about 1% weight. or higher up to saturation of the aqueous solution. The temperature at which carry out the stage of contact, can be any within the range of temperatures at which the solution is liquid; the preferred temperature is from 25 to 100oC. the Duration of contact can range from one or two seconds to hours; the more fiber, the more time contacting. All of the above variables can be set is accounted for 0.5 to 15 wt%. based on the received product; and the preferred concentration is equal to at least 1.0% weight.

The definition of "never-dried fiber" means a fiber formed from a water system and coagulated in an aqueous system and fibre water was not removed before the content is less than about 100 wt%. Not the dried fibers are open, this sponge-like structure, which usually holds from 100 to 300 wt%. water based on the weight of dry polymer. When the fibers are dried to a water content less than about 20 wt%, the molecular structure is irreversibly destroyed, and this fiber method of the present invention is no longer feasible.

I believe that the use of sulfonated PPF-T, having both a low characteristic viscosity, leads to the production of a material, which unexpectedly shows high affinity for certain metals, and in combination with such metals has very high resistance. Tungsten and molybdenum solutions are most easily absorbed aramid structures, when these structures are not dried and when the aramid has a low characteristic viscosity; metals, absorbed not dried aracteristics viscosity.

Wet and swollen fiber containing the metal in solution, then served on a stage of drying, which is necessary to obtain the final fiber. The metal that is present in aramid fibers at the stage of drying, remains in the fibers after the stage of drying in the form of oxides. For drying of the fibers does not require any special conditions. You can use any reasonable temperature, to avoid damage to the fibers from excessive heat. It is preferable to dry the fiber in vacuum on heated rolls or in the atmosphere of a moving inert gas, although it is not required; usually as atmospheric air is used.

Sulfonated having a low characteristic viscosity and containing a metal oxide fibers of PPF-T of the present invention have superior fire resistance and is particularly useful as fibers for protective clothing and similar products, as they maintain the fire resistance when exposed to flame.

Test methods

Characteristic viscosity (HV) is determined using the following equation:

XB = In(from)/c

where c represents the concentration (0.5 gram of polymer in 100 ml of solvent) of the polymer solution, for example, the ora polymer and duration of the same solvent when measured at 30oC in a capillary viscometer. The value of the characteristic viscosity, which are listed and defined in this case, represents the value obtained when using as the solvent of concentrated sulfuric acid (96% H2SO4).

The sulfur content

Yarn samples in a small amount (approximately 0.5 g) is dissolved in approximately 96% sulfuric acid, and then water is added to precipitate the polymer. Then continuously add water to thoroughly rinse the polymer and to remove from it any number of free sulfate such as sodium sulfate. The sample obtained polymer is dried and carefully weighed. After weighing, the sample is placed in a flask Lanigera for combustion in pure oxygen. Resulting from the combustion of SO2and SO3absorb water with the formation of sulfuric acid. The acid is titrated with barium chloride to determine the sulfur content, which is associated with sulfuric acid or sulfo, in the original sample yarn. The sulfur content is determined in moles of sulfur in the form of sulfo on 100 moles of the recurring units PPF-So

The fire test

The end of the sample dried yarn is attached to the stationary beam, rerat under the horizontal part of the thread and write time during which the yarn is burned through, and the weight will fall. In this test, the flame temperature is approximately 700oC. as for the test can be a substantial change of conditions, the tests presented here, is usually carried out at the same time the yarn of the present invention and the same yarn, not containing metal and used as control. The resistance is measured as the ratio of the times required in order collapsed under test yarn and a control yarn of equal weight; or, on the other hand, the weight of the yarn can be chosen to obtain almost the same time, exposure to flame up their destruction, and in this case, the resistance will be the ratio of the weights of the tested yarn and a control yarn.

The metal content

The metal content is determined using an inductive related plasma-atomic emission spectroscopy, described in the standard ASTM-C 1111-88.

Description of the preferred embodiments of the invention

The following examples illustrate the invention but they should not be construed as limiting the present invention.

Example 1

In this example, the relatively well to do spinning solution of poly(p-phenyleneterephthalamide) (PPF-T) 100, 1% sulfuric acid.

1. The solution containing 19.4 per cent weight. PPF-T, is obtained using PPF-T, having a characteristic viscosity 6,37 DL/g and a sulfur content of 0.7 mole per 100 moles of recurring units PPF-So

2. A solution containing 10 wt%. PPF-T, is obtained using PPF-T, having a characteristic viscosity 3,40 DL/g and is essentially containing 0 moles of sulfur per 100 mol of the repeating units PPF-So

3. The solution containing 19.4 per cent weight. PPF-T, is obtained using PPF-T, having a characteristic viscosity of 5.17 DL/g and a sulfur content of 6.0 moles per 100 moles of recurring units PPF-So

4. A solution containing 10 wt%. PPF-T, is obtained using PPF-T, having a characteristic viscosity of 1.97 DL/g and a sulfur content of 6.9 moles per 100 moles of recurring units PPF-So

These four spinning solution PPF-T form filaments in accordance with the methodology described in U.S. patent N 3767756.

Portions of each of the formed fibers from PPF-T not dried form is introduced into contact for 5 seconds with a solution phosphomevalonate acid and then thoroughly washed. The solution phosphomevalonate acid is prepared by adding the weight of 247.5 parts of tungstate who evania to boil the solution becomes transparent and has a pH of 2.6. Equal portions of each yarn of the PPF-T, which is not treated with a solution of tungstic acid is used as the control fibers.

Processed tungsten fiber and the reference fiber is dried overnight in a vacuum oven at 80oC. Then three samples of each fiber is subjected to the fire test, determining the time of destruction at a constant weight and the ratio of time for the treated fibers and time for the control fibers. The results of the fire test as the average values of the three variables are presented in table. 1.

It should be noted that only the processed fiber, made from a spinning solution number 4 are the fibers of the present invention obtained in this example. For unknown reasons, while fibers made from other spinning solutions were not improved in the processing of tungsten. PPF-T spinning solutions with rooms 1 and 3 has a characteristic viscosity above 4 DL/g, which, apparently, is too high to ensure adequate absorption of machining metal. PPF-T spinning solutions with rooms 1 and 2 contain sulfur less than 5 moles per 100 moles of recurring units PPF-T, which, in view of heat too high characteristic viscosity and low sulfur content.

Example 2

Fibers formed from the spinning solution number 4 of example 1, process for 5 seconds with a solution phosphomolybdenum acid. The solution phosphomolybdenum acid is prepared by adding a 49.5 weight parts of sodium molybdate and of 4.75 parts by weight of dinatriumfosfaatti to 100 weight parts of water; pH adjusted to 2.5 with sulfuric acid; after heating to boiling, the solution becomes transparent.

Processed molybdenum fibers and the corresponding control of the fiber is dried overnight in a vacuum oven at 80oC, then for three samples of each fiber is subjected to the fire test, while choosing the weight of the yarn to obtain almost the same exposure time to destruction. Determine the ratio of erodible mass for the treated fibers and destroy the mass for the control fiber. The results of the fire test as the average values of the three variables are presented in table. 2.

Example 3

Fibers formed from the spinning solution number 4, is treated by contacting within 5 seconds with vanadium solution in one variant and palladium solution in another. Vanadium solution was prepared by adding first 49,5 Weasley and then combining 18 parts by weight of this solution with the solution, containing 45 weight parts of acetic acid and 37 parts by weight of water. Palladium solution prepared by the addition of 1.4 parts by weight of palladium chloride and 12 parts by weight of citric acid to 100 weight parts of water and heat up until the solution is clear.

Achieved a 2-fold increase in resistance of the fibers treated as vanadium and palladium.

Example 4

In the present example, aramid fibers, formed from a solution of 4 of example 1, is treated by contact with solutions of tungsten different concentrations in accordance with the present invention, and test fire.

Tungsten solutions prepared by dilution of the original solution with water in the amounts shown in the table, to a total volume of 50 ml of the Original solution is prepared from a 49.5 g of sodium tungstate, and 4.75 g of sodium phosphate and 100 ml of water, adding sulfuric acid to a pH of 2.0. Before preparing the solutions of the starting solution is stirred for 30 minutes at 80oC.

The sample is not dried fibers are immersed for five seconds in each solution containing tungsten, and then immediately washed with water and dried. Determine the content of tungsten in the fibers and their onesto altoadige of the invention compared to similar fibers, not containing tungsten.

For determination of the fire resistance test yarn and a control yarn is simultaneously subjected to the fire test, in which the weight of the control yarn is 10 grams and the weight of the test yarn picked by trial and error so that both sample was burned from beginning to end, with a difference from each other within 3 seconds. Usually the yarn burns completely within 7 to 10 seconds. The resistance in this example represents the ratio of the weight of the test yarn to the weight of the control yarn. This test shows that the concentration of tungsten approximately 1% of the weight. provides a resistance of about 5 (see tab. 3).

1. The product of a poly(p-phenyleneterephthalamide)polymer, which has a 0.5 weight. % based on the total weight of the metal, where the metal is present in the form of oxides, evenly distributed throughout the product, characterized in that the polymer has a high fire resistance and has a characteristic viscosity of from 1.5 to 4 DL/g, the sulfur content in the form of sulfo from 5 to 20 moles of sulfur per 100 moles of the repeating polymer units and the metal present in the form of oxides selected from the group comprising the oxides of tungsten and oxides of molybdenum.

4. The product under item 1, characterized in that the resistance of the product at least five times more fire resistant fiber made essentially the same way using the same materials in the absence of metal.

5. The product under item 1, characterized in that the metal is present in an amount of from 1.0 to 15 wt.%.

6. The product under item 1, characterized in that it is made in the form of fibers.

7. The way to increase the fire resistance of the product of a poly(p-phenyleneterephthalamide)polymer, which comprises contacting not the product of a poly(p-phenyleneterephthalamide)polymer with an aqueous solution of a water-soluble compound of the metal in a concentration of from 1 wt.% before saturation within 2 s to 1 h and drying, characterized in that the polymer has a characteristic viscosity of from 1.5 to 4 DL/g, the sulfur content in the form of sulfo from 5 to 20 moles per 100 moles of the repeating polymer units, and a metal selected from the group consisting of water-soluble compound of tungsten and a water-soluble compound of molybdenum.

8. The method according to p. 7, wherein the metal is tungsten.

9. The method according to p. 7, the dried product contains from 100 to 300% of water based on the weight of dried polymer.

11. The method according to p. 7, characterized in that the product is made in the form of fibers.

 

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4 ex

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