CS232309B1 - Method of determine concentration of colouring agent in polyolefin - Google Patents

Abstract

The invention solves a method for determining a concentration coloring agents in polyolefins. In this way, the layer of polyolefin is processed it is washed in water and boiled and dried to a constant weight, then the polyolefin boiled in xylene at the boiling point of xylene for 15 minutes, preferably 30 minutes and the pigment dispersion in xylan is photometrically at 140 ° C - 2 ° C at room temperature wave length corresponding to maximum absorption! light for the color and evaluate compared to the standard, prepared in the same way. There is also a way to proceed so that the polyolefin is cooked in xylene containing 0.1 to 10% by volume of monovalent or polyhydric alcohol, or aliphatic carboxylic acid or its ester, with 3 to 20 carbons in molejcule. The method of the invention removes the fibers shortcomings of the methods used so far, respectively, adding methods for determining concentration dyes in polyolefins. A method of determining the invention is possible used to evaluate the coloring power of pigments in coloring polyolefins in the mass.

Description

The invention relates to a method for the determination of concentrate colorants in polyolefins.

Polyolefins, due to their non-polar character and the inability to bind dyes through functional groups, are mainly dyeed by incorporating colored pigments or soluble dyes into the polymer mass. Especially when dyeing fibers based on polyolefins, it is required to control the dye content of the polymer. The application of conventional colorimetric assays has encountered difficulties associated with the insolubility of isotactic polyolefins in organic solvents at lower temperatures and the agglomeration of pigments after dissolution, due in particular to the dispersants used. At present, the pigment content of the polyolefins is determined gravimetrically after multiple centrifugation and extraction of the polymer from the xylene solution at 140 ° C.

The disadvantages of the method include inaccuracy in the determination due to the non-quantitative removal of the polymer caused by strong adsorption on the surface of some pigments, the difficulty of stripping some pigments, the handling of large amounts of xylene at near boiling point, the impossibility of determining low pigment concentrations. Pigmentation can also be determined in fibers or foils based on remission measurements according to the Kuvelka-Munk equation.

Measurements are accurate and evaluated using physical devices. The result of the assay is characterized by the coloring of the fibers or foil. However, the accuracy of the method is greatly dependent on the fineness of the fiber and how the fiber is deposited in a measurement that is standardized. The method requires the preparation of standard fibers for each meranle, which is a disadvantage.

The above drawbacks are eliminated in the method for the determination of concentrating dyes in polyolefins n by determining the extinction of the color dispersion at the maximum wavelength of the respective color of the dispersion and comparing it to a standard based on the polyolefin sample being washed in boiling water and dried to constant weight. then the polyolefin is boiled in xylene at a boiling point of xylene for at least 15 minutes, preferably 30 minutes, and the pigment dispersion in xylene is determined photometrically at 140 ° C to 2 ° C corresponding to the maximum light absorption for the coloration and evaluated by comparison with a standard prepared in the same way. Alternatively, the polymer can be boiled in xylene containing from about 0.1% to about 10% by volume of a monovalent or polyvalent alcohol or an aliphatic carboxylic acid, or an ester thereof having 3 to 20 carbons per molecule.

In the method of the invention, a comparative method is used. A dispersion having a different weight per 100 ml of solvent is prepared from a tow with a precisely known pigment content of, for example, 2%. The dispersion was transferred to a reflux condenser tube tempered to 140 ° C in a heating block. The tube is then placed in the instrument and measured for extinction. The solvent is used for comparison in the measurement. The effect of the soluble polymer on the measurement is negligible. In each assay, it is necessary to maintain the exact procedure of dissolution, the temperature regime before aeration and the orientation of the tube in the measuring device.

Before measurement of the fiber, pulp or film sample, it shall be washed by boiling in water, for example for 2 hours and dried at 105 ° C to constant weight. Similarly, a polymer dispersion in xylene is prepared by dissolving the sample to be examined and, after measuring its extinction by comparison with a standard in a suitable manner, the concentration of the coloring agent is calculated.

Extinction is measured at a wavelength of light corresponding to the maximum absorption of the dye.

The influence of the soluble polymer on the measurement is negligible, similar to the change in extinction does not occur due to the temperature between the boiling point of the solvent at 138 ° C and the temperature at which the polymer starts to fall out of solution is 80 to 110 ° C. The addition of an alcohol, an aliphatic carboxylic acid or their esters in xylene has an effect on the dispersion of the pigment after the polymer has dissolved. The pigment dispersion is more stable and the measurement results have better reproducibility.

To assess the concentration of the coloring agent, the calibration dependencies shall be measured, based on the Lambert-Beer law, for example:

(a) as the extinction (E) dependence of the coloring agent concentration in the fiber (c) at the same fiber weight (h) per 100 ml solvent, E = fc. The dye concentration in the fiber sample (pulp) c _y is determined after dissolution (weight h _y / 100 ml solvent) and extinction measurements, subtracting c _y from the calibration dependence,

b) that the dependence of the extinction of the weight of fiber per 100 mL of solvent at a constant level of the coloring composition of the fiber = E _c · fh concentration of coloring agent in the sample (mash) c _y was determined after dissolution in lubovol'nej weight _yl h to 100 mL of solvent and after extinction measurement E where c _y - concentration of coloring agent in the pulp in%

Cg - concentration of colorant in Standard in% h _y - weight of sample / 100 ml of extinction solvent E h _g - weight of Standard / 100 ml of extinction solvent E from calibration. Valid E. - K, ^{n n}

(c) where appropriate, the constant K = c is determined for a given dye and for a certain concentration of dye in the fiber. h for E = constants (eg E = 0,3), where c - dye concentration in the fiber, h - fiber weight per 100 ml. The concentration of coloring agent in the sample sampled c _y is determined by determining the fiber weight h _y / 100 ml of extinction solvent E at which the constant K was determined, for example E = 0.3, then _γ = K / h _y .

Prior to determination, the tubes should be calibrated for internal diameter unevenness by determining the light transmittance of the dye dispersion at the maximum absorption to the selected base tube.

Advantages of the method according to the invention include the operability and speed of determination without pre-preparation of standard fibers, low energy and chemical consumption and simple solvent recovery. It is possible to determine the concentration of coloring agents in polyolefin fibers and concentrators from a low concentration of 0.01% and also to determine the colorant concentration in the color concentrators.

The examples below illustrate the subject matter of the invention.

Example 1

Polypropylene fibers, previously washed by boiling with water for 2 hours, dyed with yelow 95 pigment with an exact pigment content of 0.4% by weight, are placed in a tear tube. in the following amounts: 0.030, 0.050, 0.090 and 0.129 g / 10 mL of a solvent consisting of 98 parts by volume xylene and 2 parts by volume n-butyl alcohol. The tubes are placed in a 150 [deg.] C tempered electric block and mounted on the back condensers and the samples dissolve for 30 minutes while boiling. After dissolution, the tubes are removed from the block and, after cooling below the boiling point, the extinction of the dispersion is measured at 430 ° C. The measured extinctions were as follows according to the above weights per 10 ml of solvent: 0.120, 0.251, 0.366, 0.494, 0.680. The graphically determined fiber weight (10 ml solvent for E-0.3) (permeability = 50%) is hg = 0.059. 4 From ten dependencies, the average value of hg = 0.059 was determined for 0.4% dye in the fiber and E = 0.3.

From the measured values, the coefficient K = hg was calculated. c _g = 0.059. 0.4 = 0.023 6.

When determining the concentration of gelb GR in the polypropylene wax, the results shown in Table 1 were obtained.

T a b u 1 'k a 1

Předpokl. conc. % of pigment in the tow% wt.

0.1

0.2

0.6

0.8 h _y for Determ.

E = 0.3 of pigment in the spinner, c _?

0.23 0.102 0,00 0.002 0.116 0.203 - 0.005 0.039 0.605 0,01 0.015 0.031 0.761 - 0.019

Example 2

A polypropylene fiber having a pigment content of blue 15 of 0.8, 0.6, 0.2, 0.1% by weight was placed in a 250 ml three-necked flask. with a constant weight of 0,2 g / 100 ml solvent consisting of 97 parts by volume of xylene and 3 parts by volume of n-octanol. In the heating nest, the fibers are dissolved in the flasks at the boiling point of the solvent for 30 minutes. After lowering the temperature to below the boiling point of the solvent, a portion of the dispersion is removed through the adapter into a test tube, which is tempered in an electro block at 140 ° C under a bad condenser prior to measurement.

The measured extinctions (at 620 nm) of 0.620, 0.482, 0.187 and 0.092, depending on the above pigment concentrations in the fiber, represent a linear calibration dependence.

1: 1 weight blends were prepared from the above fiber samples, and the concentrations were determined after measuring the extinction of the dispersions containing 0.2 g fiber mixture / 100 ml solvent by subtracting from the calibration dependence. The measurement results are shown in Table 2.

Table 2

1: 1 fiber mixture containing pigment Estimated pigment concentration in fiber,% wt. extinction dispersions 0.2 g / 100 ml Pigment concentrations measured in the extruder,% wt 0.2% + 0.8% 0.50 0,305 0.505 - 0.013 0.1% + 0.6% 0.35 0,278 0.348 - 0.009 0.4% + 0.6% 0.50 0,393 0.503 - 0.012 0.1% + 0.4% 0.25 0,210 0.249 i 0.006

Example 3

In 250-ml three-necked flasks, the solvent of polypropylene fiber containing 0.2 wt. Pigment red 166 of 0.2, 0.3, 0.5 and 0.7 g / 100 ml solvent containing 97 parts by volume of xylene and 3 parts of benzyl alcohol. The measured extinctions were 0.025, 0.098, 0.254 and 0.398. From these measurements, the dependence of extinction on fiber weight per 100 ml solvent was determined by calibration. Extinction was measured at 560 µl.

A dispersion (b) of 0.025 g / 100 ml of solvent according to Example 2 was prepared from the crushed samples of polypropylene concentrate with an assumed concentration of 5.0% by weight. in the pulp c _y = Cg. h ^ / h ^ = 0.2. 0.67 / 0.025 = = 5.36% - 0.15.

For the polyethylene concentrate, the dispersion extinction was 0.370, hg from a calibration dependency of 0.65, and the pigment concentration in the pulp c _y = c _g . hg / h _y = 0.2. 0.65 / 0.025 = 5.2% - 0.15.

Example 4

According to Example 2, a colored yellow polypropylene fiber solution containing pigment yellow 95 at a concentration of 0.6 g / 100 ml of solvent was prepared consisting of 98 volumes of xylene by volume and 2 parts by volume of n-butanol at the boiling point of the solvent. Table 3 shows the results of extinction measurements of some samples and their comparison with fiber remission measurements on an Opton device. As the table shows, the results are comparable.

Table 3

vz.e. remission rfs _r (%) extinction RFS _e (%) 1 5.39 100 0,320 100 i 2,5% 2 6.43 82 0,284 88 í 2,5% 3 5.01 108 0,333 104 - 2.5% 4 4.74 15 0,361 113 ^J 2.5% 5 5,20 - , 04 0,331 103 or 2.5% 6 4.93 110 0,339 106 i 2.5 « -y, ........

Relative color force according to Kubelka - Munkovek equation RFSg = ^J. 100

K / S 'Standard * where K - adsorption coefficient, S - scattering coefficient. The relative color strength RFSj, is expressed as E _y / Eg 100 100, where E _y - sample extinction, Eg - standard extinction.

Example 5,

Preparation of the calibration dependence was performed as in Example 1. A solvent containing, parts by volume of xylene and 2 parts by volume of stearic acid was used to determine the pigment concentration of yellow 95 polypropylene fiber.

The results of the assay are shown in Table 4

Table 4

Předpokl. % pigment concentrate in fiber% wt. h _y for E = 0.3 Determined pigment concentration in fiber _? 0.2 0,119 0.198 and 0.005 0.6 0,038 0.609 - 0.015 0.8 0,030 0.782 - 0.019

OBJECT OF THE INVENTION]

Claims (2)

1. Method for determining * the concentration of coloring agents in polyolefins by determining the extinction of the color longitudinal dispersion at the maximum wavelength of the respective color of ¹ dispersion and comparing it to the Standard, characterized in that the polyolefin sample is washed in boiling water and dried in a constant bath the polyolefin is boiled in xylene for at least 15 minutes, preferably 30 minutes, and the dispersion of the plgaent in xylene is determined photometrically at 140 ° C - 2 ° C at a wavelength corresponding to maximum absorption! lights for a given color and evaluated by comparison with the standard. 2. The method of claim 1, wherein the polyolefin is boiled in xylene containing from about 0.1% to about 10% by volume of a monovalent or polyvalent alcohol or an aliphatic carboxylic acid or ester thereof having from about 3 to about 20 carbons per molecule.