Electric conducting para-amide pulp

FIELD: production of electric conducting pulp for manufacture of paper, reinforcing polymer materials and packaging films.

SUBSTANCE: pulp contains fibrous particles including 65-95 mass-% of para-amide and 5-35 mass-% of sulfonated polyaniline containing sulfur in the amount of 8.5-15 mass-% which is dispersed over entire para-amide partially covering the particles externally. Specific area of surface of fibrous particles exceeds 7.5 m2/g. Pulp may be mixed with 95 mass-% of pulp of other material including poly-n-phenylene terephthlamide. Paper made from this pulp reduces rate of electric charge lesser than 150 ml.

EFFECT: enhanced efficiency.

6 cl, 4 tbl, 1 ex

 

1. The scope of the invention

The present invention relates to conductive aramid pulp of a certain composition, which has a large surface area, high concentration of fiber, which contributes to the strength and modulus of elasticity when used as a reinforcing environment for polymeric materials.

2. Description of the prior art,

In U.S. patent No. 5788897 and No. 5882566, issued August 4, 1998 and March 16, 1999, respectively, described fiber having a continuous phase of paraaramid and discontinuous phase of the electroconductive from sulphonated of polyaniline.

In U.S. patent No. 5094913, issued March 10, 1992, describes a slurry, formed from fibers having a continuous phase of paraaramid and discontinuous phase of metronida.

In Japanese patent publication (Kokai) No. 59/163418, published on September 14, 1984, described the pulp, refined from fibers of a mixture of paraaramid and aliphatic polyamide.

Brief description of the invention

Conductive pulp is very necessary product for reinforcement of packaging films and polymeric materials, generally, and especially in those cases when there is a need for the removal or dissipation of electric charges. Conductive pulp finds application in areas where the use of pulp-dialect the ICA, in the dry form, there are charged particles that are difficult or even dangerous to ask for fear of the spark discharge.

The present invention results from the pulp, which is not only beautiful reinforcing material, but also an extremely effective tool for dissipation of electric charges. In addition, the material is excellent for providing such dissipation of electric charges, is a material through which simplify the production of pulp and give very good properties of the pulp. The present invention also created the pulp, which can be used for the manufacture of paper.

Conductive pulp for making paper or reinforcement of polymeric materials and packaging films according to the invention includes fibrous particles comprising 65-95 wt.%. paraaramid and 5-35 wt.%. from sulphonated of polyaniline with a sulfur content of 8.5-15% wt., dispersed throughout paraaramid and partially covering the particles externally, and fibrous particles have a specific surface area of more than 7.5 m2/, When this pulp has a Canadian standard freeness of less than 150 ml.

Paper made from pulp according to the invention, has the speed of decrease of electric charge less than 5 seconds.

Preferably paraaramid is poly-p-fineliner phthalamide.

The present invention also relates to a mixture for making paper or reinforcement of polymeric materials and packaging films, characterized in that the mixture contains at least 5 wt.%. the above conductive pulp and 95% wt. pulp made from another material.

Preferably the mixture for the manufacture of paper and reinforcement of polymeric materials and packaging films as another material contains poly-p-phenyleneterephthalamide.

Detailed description of the invention

In this invention using the close mixing of the two polymer materials for producing pulp, which is not only a good reinforcement tool for other polymers, but also is electrically conductive structure through which inform conductive properties are typically a dielectric material, at its introduction the purpose of reinforcement. Fibers from the linked polymers are known. Especially fiber from paraaramid connected with other polymers, and even with polyaniline polymers is known. However, to date no proposals to use such fiber in the refining process for manufacturing conductive pulp.

The materials from which to form the slurry, are: paraaramid and SPA, and through SPA-component provide a double f is ncciu purposes widely divergent and strongly interconnected. First, using polyaniline, which is the secondary component of the mixture, creating a break point for forces, aimed at refining and pulp education to ensure effective production of high quality pulp containing long, thin fibers. Secondly, polyaniline, as a component, effectively located on the surface of particles of the pulp, contributes to the creation of the conductivity, which occurs the effective dissipation of electrical charges at the contact of the fibers of adjacent particles of the pulp.

The term "aramid" here understand the polyamide in which at least 85% of the amide linkages (-CO-NH-) attached directly to two aromatic rings. Aramid fibers described Vblack and others in the publication "Synthetic fibers - Science and technology", volume 2, section "fiber-forming aromatic polyamides", page 297, the Publishers minutnym problems, 1968 Aramid fibers are also described in U.S. patents№4172938, №3869429, №3819587, №3673143, №3354127 and no 3094511.

Paraaramid are the main polymers in the present invention and are intended to be mixed with polyaniline; poly-p-phenyleneterephthalamide is the preferred paraaramid. The term "paraaramid" here understand a homopolymer obtained by polymerization when Odie is ukovich Malevich shares of paraphenylenediamine and terephthaloylchloride, as well as copolymers obtained by the inclusion of small amounts of other diamines with paraphenylenediamine and small quantities Dalilah chlorides with terephthaloylchloride. As a rule, other diamines and other docile chlorides can be used in amounts up to about 30 mol.% from paraphenylenediamine or terephthaloylchloride or perhaps several big imposed only in cases when other diamines and docile chlorides do not contain reactive groups that react polymerization. The term "paraaramid" here also understand the copolymers obtained by the introduction of other aromatic diamines and other aromatic Dalilah chlorides, for example, 2,6-naphtalimide or chlorine - or dichlorotetrafluoroethane imposed only when other aromatic diamines and aromatic docile chlorides are present in amounts that allow the preparation of anisotropic spinning solution. Cooking processes paraaramid and forming fibers from paraaramid described in U.S. patent No. 3869429, No. 4308374, No. 4698414 and No. 5459231.

From sulphonated polyaniline according to the present invention can be produced by the sulfonation in the core in place. The words "the sulfonation in the core in place here understand that polyaniline sulfonic during the process dissolved the I polymer, and not in isolation from the dilution of sulfuric acid before from a solution is formed into a fiber. Of course, the sulfonation can also be done any other way to get from sulphonated of polyaniline, which leads to the formation of conductive pulp.

In order for the present invention was effective in practice, from sulphonated polyaniline must be from sulphonated to such an extent that through it ensured adequate conductivity for dissipating electrical charges. It is established that the sulfonation is required to sulfur, at least, constituting 8.5% of the total mass from sulphonated of polyaniline. The sulfonation in the volume, the smaller this quantity, leads in General to inadequate conductivity fibers. It was also established that increased sulfonation provides improved up to the level of sulfating, amounting to about 15 wt.% sulfur from total mass from sulphonated of polyaniline. The sulfonation to a higher degree, as defined, contributes little additional improvement in properties. It is noted that the sulfonation of polyaniline to 8.5-15 wt.% corresponds to the sulfonation molar fraction corresponding to 30-70% polianilinovyh structural units.

Pulp according to the present invention can be manufactured by the so-called molding process "air gap" anisotropic spinning solution, includes paraaramid and from sulphonated polyaniline. Description of the preparation processes of such a spinning solution and forming fiber that could be used as the basis of the pulp used in the present invention, may be found in previously mentioned U.S. patents No. 5788897 and No. 5882566.

The molecular weight of the polyaniline used in the pulp according to the present invention, is not critical. Application of polyaniline low molecular weight may result in a lower viscosity and easier process, however, it can be more easily removed from the fiber during processing or use.

Use paraaramid greater molecular weight, having inherent viscosity component, at least 5. In order to obtain a pulp of the desired high strength and high modulus of elasticity, use a spinning solution with a concentration of paraaramid, in which the result is obtaining anisotropic spinning solution, as described in U.S. patent No. 3767756. Spinning solutions containing at least 13 wt.% from the overall content of the polymers, i.e. from sulphonated of polyaniline and paraaramid, meet these requirements. Otherwise, the mechanical properties of the formed fibers do not Bud the t is acceptable for making pulp to provide antistatic properties.

Concentration from sulphonated of polyaniline in paraaramid in the spinning solution and, ultimately, molded fiber or pulp, have an important influence on its properties. By increasing the content from sulphonated of polyaniline up to and in excess of the values in 40 wt.% from a mixture of polymers, the tensile strength of the fibers becomes undesirable reduced in the absence of a concomitant increase conductivity. In addition, when washing the fiber with such a high concentration of polyaniline, a number on the place from sulphonated in the nucleus of polyaniline can be derived.

From sulphonated core polyaniline should be at least 3 wt.%, and preferably more than 5 wt.% pulp to ensure speed removal of electric charge less than approximately 5 seconds. From sulphonated core polyaniline should be 3-40 wt.%, and preferably 5-30 wt.% fiber by weight of the polymer mixture based on the use of Desulfovibrio of polyaniline.

For the manufacture of pulp according to the present invention, filament, formed in accordance with the above description, stapeliad, receiving a fiber length of 5-25 mm, and prepare a water suspension to form a flocculant, which is subjected to high shear deformation for forming the pulp can be used equipment, suitable for refining cellulose fibers, for example, a refiner equipped with peretiranie working bodies, driven in rotation one relative to another. When the slurry formation according to the present invention the shear deformation along the boundaries between the phases of paraaramid and polyaniline easily lead to the formation of high-quality particles with a very good average fiber length pulp and a high degree of fibrillation. The presence of domains of polyaniline provides a break point in shtapelirovannojj fiber and leads to easy and more full of atrial reduced energy consumption, and the surface of the particles of the pulp, at least partially, determined by the location of the domains of polyaniline held in the fibers. As a result of such distribution, at least some of the outer surfaces of the pulp have a relatively high concentration of polyaniline and unexpectedly high electrical conductivity.

One reliable indicator of the degree of fibrillation and level surface area product of the pulp is the "Canadian standard freeness" (CSF). Under CSF pulp understand the amount of drained water specified in the special tests described in this application below. Pulp suitable for use in the present invention, generally corresponds to the CSF, sostavlyajushie is from 0-150 ml, and preferably 20-100 ml lower value of CSF is usually some definition to the greater surface area.

The composition of the pulp according to the present invention may include a combination of a mixture of slurries consisting of two pulp and the pulp is made of a different material. In this case, it is required only that the composition is contained as many two-component slurry as necessary to achieve the desired speed of attenuation of the electric charge. The compositions, where the rate of attenuation of the electric charge is less than 5 seconds, fall under the scope of action of the present invention. The number of two-component slurry required to achieve this speed reducing electric charge can be varied depending on the amount of sulfur from sulphonated the polyaniline and the number from sulphonated of polyaniline in two component slurry. Typically, the compositions of the mixtures, which form the pulp should include at least 5 wt.% two pulp and less than 95 wt.% pulp of other material by weight of the total composition.

Component of the pulp made from another material, can be prepared from any material suitable for the formation of the slurry, including, for example, cellulosic material, acrylics, paraaramid etc. Preferred the other material pulp is a para-aramid material, poly-p-phenyleneterephthalamide.

Test methods

The dissipation of electrostatic charge

When testing for the reduction of electrostatic charge or scattering determine the ability of a material when it is ground, known to dissipate the electrostatic charge induced on the surface of the material. To determine the dissipation of electrostatic charge pulp produced in these examples, the pulp is processed into sheets of paper and have tested on the scattering of electrostatic charge on the leaves.

5 g of pulp was dispersively for 5 minutes in 1.5 liters of water disperser TMI (firm "Testing machine. Inc., Hollandia, new York, USA). The resulting dispersion was poured into headbox laboratory paper machine, containing 25 l of water. Formed manually sheet size 300×300 mm, obezvozhivani and dried it.

From sheets cut sample size (90×140 mm), designed for testing the speed of decrease of the electrostatic charge, was kondicionirovanie them, at least for 24 hours at a relative humidity of 30% and tested on the unit ETS to determine the reduction of electrostatic charge (model S firm "Power. Systems, Inc.).

During testing, the samples were placed between the electrodes of the measuring device, created the charge in 5000 and in case of grounding electrodes measured the time to reduce the amount of charge up to 500 C. These tests comply with Federal test method standard V, Method 4046, known as "Trials to reduce the electrostatic charge. The test results presented in table IV.

The sulfur content

A sample of the pulp is known for mass burned in the flask with oxygen; the resulting gases SO2and SO3absorbed in water. Water was added hydrogen peroxide to ensure that all sulfur was converted to sulfate; water is boiled using a platinum mobiles to remove any excess H2O2. The resulting solution was combined with the same volume of isopropanol and was titrated standardized solution of BaCl2to determine the concentration of sulfate. The amount of sulfur was determined by the concentration of sulfate.

Length (fiber) pulp

The fibre length of the pulp was measured using the instrument model Kajaani FS-200 (firm Kajaani Electronics, gkaan, Finland). A water suspension of pulp fibers were prepared with a concentration corresponding to the speed of analysis, comprising 40-60 fibers per second. The suspension was passed through a capillary device for exposure by a laser beam and detector to determine the length of the fiber. With the help of the device was performed calculations on the output signal of the detector and identified three different lengths: average length, with ednisolone length (based on the length of the fibers) and weighted average fiber length (based on the weight of fibers).

Strength properties

For determination of strength properties take, first, the elementary fibers, air-conditioned at 25°C, 55% relative humidity for at least 14 hours; strength tests were performed under these conditions. Strength (tensile strength), elongation (breaking elongation) and the modulus of elasticity was determined by the tearing of elementary fibers on a tensile testing machine "Instron" (firm "Instron engineering, Inc.", glanton, strassacker, USA).

Tensile strength, elongation and modulus, as defined in ASTM d2101 drivers-1985, was measured using the lengths of filaments, equal to 25.4 mm Tensile strength was determined in g/denier. The modulus of elasticity was calculated by the slope of the curve chart load-elongation" at 1% elongation; believed that the modulus of elasticity is equal to the load in grams at 1% elongation (absolute value), multiplied by 100, divided by the fineness (denier) of the test of filaments. The fineness of filaments (denier) was determined according to method ASTM D1577 using vibroscope.

Specific surface area

Square surfaces was determined using single-point method of Brunauer-Emmett-teller absorption of nitrogen, was used Strohlein apparatus for determining the surface area (by "Standard Instrumental, Inc., gcarlson, Tsumada Virginia, USA). The washed pulp samples were dried in a weighed flask samples were weighed and placed in the instrument. Nitrogen was absorbed when the temperature of the nitrogen in the liquid state. Adsorption was measured pressure drop between the flask with the sample and the reference flask (manometer readings); specific surface area was calculated based on the manometer readings, barometric pressure and the mass of the sample.

Canadian standard freeness (CSF)

This figure represents the amount of drainage of the suspension, consisting of 3 g of fibrous material in 1 l of water. Measurements and instruments consistent with the TAPPI standard T227 om-94 (TAPPI - Technical Association of paper industry of the USA). Fibrous material was dispersively for 5 minutes in a disperser model TMI. The results are presented in the form of volume (ml) of water drained under standard conditions. The measured volume was influenced by fineness and flexibility of the fibers and the degree of fibrillation.

Examples

Preparation of fiber

In the following examples, the composition of the pulp according to the present invention were characterized by various concentrations of polyaniline.

Usually spinning solution was prepared as follows:

Double spiral mixer ("Atlantic") were heated to 80°With, blew nitrogen and downloaded it concentrated sulfuric acid (100,1%) and polyaniline PR is constant moderate stirring and purging with nitrogen. Quantities of materials shown in Table I. (Polyaniline was dried in a vacuum oven at a temperature of about 18°With during the night.)

Table I
% SPAH2SO4gPA gPPDT, gThe number of particles, %
5145,41,7533,219,4
10to 166.24,036,019,4
20153,27,028,018,6

The mixture was stirred for 1 hour at a temperature of 52°and then was cooled to -42°using a bath of dry ice and acetone before adding poly-p-phenyleneterephthalamide (PPDT). (PPDT was dried in a vacuum oven at a temperature of about 84°With during the night.) A bath of dry ice and acetone was removed, and stirring the obtained spinning solution was continued an additional 1 hour in the presence of nitrogen at a temperature of 70°C. For deaeration of the solution was mixed under vacuum at a temperature of about 80°C for another 1 hour, the solution was poured into a spinning shaft at a temperature of 80°C.

Spinning the shaft is mounted for spinning with an air gap and supplied spinning what eleroy with 10 holes with capillary channels with a diameter of 0.076 mm and a length of 0.23 mm. The temperature of the spinning shaft and the die was maintained at a level of 80°and the filament was formed using an air gap of 10 mm in a water bath at a temperature of about 1°C. the Performance of regulated so that the maximum jet velocity of 20.8 m/min, the filament was wound with a velocity of 145 m/min when the drawing ratio during formation of 7.0.

Characteristics of filaments obtained are shown in table II.

Table II
% SPALinear density, Tex (Dpf)Tensile strength, g/denierElongation at break, %The modulus of elasticity
50,266 (2,4)23,66,4358
100,255 (2,3)22,65,9417
200,277 (2,5)of 17.56,4272

Table II:

Dpf - fineness filament, denier;

Modulus of elasticity - the modulus of tensile elasticity.

Preparation of pulp

Filament obtained in the above process, stabilirea with the formation of flock length of 0.64 to 0.95; the flock was ropinirole using laboratory atmospheric refiner (size 30 with whom) batches for processing, contains plates of Andritz-Sprout Bauer brand "D2A501". The suspension is prepared from approximately 20 g of the flock in 700 ml of water, was applied to the refiner by a screw feeder and filled in the discharge area of the refiner. The feeder was washed with a small amount of water and washed away the remains were also collected. The material after the first iteration was applied again through the refiner and picked up again. This process was repeated a total of 3 times for the manufacture of product according to the present invention. Characteristics of the slurries formed from several types of flock, are presented in table III.

Table III
Length Kajaani
% SPACSFSSA% SulArLwtWwt
59512,911,7-12,60,240,861,88
1092,9212,112,0-12,6H.o.H.o.H.o.
1032,3514,612,0-12,60,350,941,81
206011,9 of 10.6 to 10.70,350,991,80

In table III:

CSF - Canadian standard freeness;

SSA is the Specific surface area, m2/g;

% Sul - sulfur Content (%) (based from sulphonated of polyaniline);

Ar - arithmetic mean length;

Lwt - weighted average length based on the length of the fiber;

Wwt - the average length based on weight of fiber.

Produced sheets of paper, using the pulp and, in selected cases, the pulp is combined with the pulp from paraaramid. Paraaramid was presented to the poly-p-phenyleneterephthalamide, and para-aramid pulp had a Canadian standard freeness (CSF), equal to 155 ml, and the specific surface area (SSA) of 8.5-9.5 m2/year Rate reduction of electrostatic charge (SDR) was determined in this paper. The test results presented in table IV.

Table IV
Time reduction charge (seconds)
% SPA* pulpCSFSSAThe mixture slurries SPA/aramidAverageRange
59512,9100/01,0109212,1100/02,71,5-3,3
206011,9100/00,010-0,01
206011,960/400,010,01-0,01
206011,930/700,010,01-0,02
206011,920/800,110,08-0,17
206011,910/902,71,9-3,7
01558,90/100>30**>30->60**

In table IV:

* Calculation based Desulfovibrio of polyaniline;

** - Behavior typical of neotestamentica material. The sample did not take the full charge voltage of 5000 C. Partial charge, which was adopted, was not easily dispelled. Tests were terminated after 30 or 60 seconds. In column a Mixture of pulps" aramid pulp was introduced commercially supplied by DuPont (E.I. du Pont de Nemours and Co.) under the trade the arch "merge 1F361" poly-p-phenyleneterephthalamide pulp.

1. Conductive pulp for making paper or reinforcement of polymeric materials and packaging films comprising fibrous particles comprising 65-95 wt.% paraaramid and 5-35 wt.% from sulphonated of polyaniline with a sulfur content of 8.5-15 wt.%, dispersed throughout paraaramid and partially covering the particles externally, and fibrous particles have a specific surface area of more than 7.5 m2/year

2. Conductive slurry according to claim 1, characterized in that it has a Canadian standard freeness of less than 150 ml.

3. Conductive slurry according to claim 1, characterized in that the paper made from this pulp has a speed reducing electric charge less than 5 C.

4. Conductive slurry according to claim 1, characterized in that paraaramid is poly-p-phenyleneterephthalamide.

5. Mix for the production of paper or reinforcement of polymeric materials and packaging films, characterized in that it contains at least 5 wt.% pulp according to claim 1 and 95 wt.% pulp made from another material.

6. Mix for the production of paper or reinforcement of polymeric materials and packaging films according to claim 5, characterized in that as other material it contains poly-p-phenyleneterephthalamide.



 

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