RU1736252C - Method of determination of density of nap coating - Google Patents

Abstract

FIELD: textile industry. SUBSTANCE: optical transmission T_max of nap layer is determined for sample with known maximum achievable flocculent density of nap for given conditions. Optical transmission T of nap layer of examined samples manufactured with same nap is measured under same flocculating conditions and their densities are found by formula n = n_max(1-T)/(1-T_max).. EFFECT: enhanced authenticity of method. 1 dwg, 1 tbl

Description

 The invention relates to methods for testing and quality control of textile materials with pile applied in an electric field.

где ΔP разность масс образца до и после нанесения ворса;
d диаметр одного волокна;
l длина волокна;
ρ плотность материала ворса.To measure the density of the pile coating, i.e. the number of fibers per unit area, there is a method of gain, which consists in the fact that a sample of a unit area is weighed on an analytical balance before and after applying the pile, and the density is determined by the formula
n

where ΔP is the mass difference of the sample before and after applying the pile;
d diameter of one fiber;
l fiber length;
ρ is the density of the pile material.

 The diameter of one fiber and its length is determined under a microscope.

 This method is a destructive material, in addition, the value of the obtained density contains a significant error due to the heterogeneity of the fibers along the length and thickness.

 A known method for determining the density of the pile coating by optical transmission of samples with pile cover, which consists in constructing a calibration dependence of the density of the pile (determined in some other way) from the optical transmission for different pile density.

The disadvantages of this method are:
time consuming to build a calibration dependence, since it is required to produce and measure at least 8-10 samples with different densities:
changing the pile length, diameter, material, color, electrophysical parameters, application conditions, for example, electric field strength, requires the construction of a new calibration dependence
the accuracy of the method is inevitably low for low pile densities due to the large error in determining small pile weights.

 The aim of the invention is to increase the accuracy of determining the density while reducing the complexity of the measurement process.

 The drawing shows a graph showing the results of measuring the density by weight and by the proposed method.

 The method is implemented as follows.

Pile material with maximum density is illuminated with a parallel beam of monochromatic light. At the same time, the same source and in the same way illuminate a sample of the base with an adhesive layer, which were used for applying pile. Both optical signals are recorded by the same sensors. So get the value
T _max = I _max / I _o , where I _{max the} intensity of the light transmitted through the sample with a density of n _max ;
I _{o the} intensity of the light transmitted through the sample with a density n = 0, i.e. through the base with an adhesive layer.

Next, the optical transmittance I for the sample under study is similarly measured and the value T = I / I _{b is} determined. After that, it is easy to determine its density n by the proposed formula. A sample with maximum density is obtained by repeated flocking (usually three times) until the pile gain after the 1st flocking is Δm _i <Δm _i and, for example, the density of the pile on it is determined by the gain, i.e. the value of the maximum allowable density for a given pile is uniquely associated (through the average orientation of the pile) with flocking conditions and is a parameter of this process, independent of the application time. In addition, since this density is maximum and does not depend on the time of application, its determination by weight gain is possible with the greatest accuracy. Thus, by measuring the optical transmission through only one manufactured sample with a known maximum density before the flocking process begins (taking into account the influence of the base with the adhesive layer can be easily automated in a two-channel optical scheme), the pile density n of any sample is determined in absolute units for this pile and flocking conditions. Measurements can be carried out both in static and in continuous mode in the production of flocked materials.

PRI me R. The studied samples were obtained by applying viscose pile with a length l = 0.5 mm and a diameter d = 0.2 mm in an electric field on a fabric substrate with an adhesive layer for 3-60 s. The voltage at the electrodes is 60 kV. The distance between the electrodes is 120 mm. The sample with the highest attainable density was obtained by triple flocking for 30 s each. Its final density is 568 1 / mm ² . Data on the density measured by weight and by the proposed method are presented in the table and for clarity on the graph for all samples. For measurements by the proposed method, a two-channel optical scheme is used, where a base with an adhesive layer is installed in one channel, and samples with a pile layer are studied in another. Then a difference signal is obtained, thereby excluding the influence of the base with an adhesive layer. Calculate the error obtained by measuring the density of the pile according to the method of gain, which is shown in the table.

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Из приведенных данных видно, что погрешность определения плотности ворса по методу привеса для малых значений плотности весьма велика и составляет 8-12% что неизбежно приводит к высокой погрешности при построении градуировочной зависимости согласно известному способу. Это же видно на графике. Разброс точек плотности ворса на градуировочной зависимости (по известному способу) значительно больше, чем по предлагаемому способу.

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From the above data it is seen that the error in determining the density of the pile according to the weight gain method for small density values is very large and amounts to 8-12%, which inevitably leads to a high error in the construction of the calibration dependence according to the known method. This is also visible on the chart. The spread of density points of pile density on the calibration curve (by the known method) is much greater than by the proposed method.

In the penultimate row of the table (example 1) there is no density value, since according to the proposed method, the value determined by the gain n _max = 568 1 / mm ^{2 was} taken as the limiting density.

Величину

получают, устанавливая в один канал основу с клеевым слоем (сигнал I_o), а в другой канал либо образец с предельной плотностью n_макс (сигнал I_макс), измеряя при этом сигнал, пропорциональный I_o-I_макс, либо измеряемый образец, получая сигнал, пропорциональный I_o-I. Затем берут отношение

Т.е. для измерения плотности ворса необходимо знать лишь величину n_макс и I_o-I_макс, после чего по величине I_o-I автоматически определяют соответствующую плотность n.The straight line shown in the graph was obtained by the least squares method using pile density data calculated by pile weight gain on all nine samples. The formula of this straight line is written taking into account normalization by the value (1-Imax / Io) and looks as follows:
n 6.9 + 560

Magnitude

receive by installing in one channel a base with an adhesive layer (signal I _o ), and in another channel either a sample with a maximum density of n _max (signal I _max ), while measuring a signal proportional to I _o -I _max , or a measured sample, receiving signal proportional to I _o -I. Then take the attitude

Those. to measure the density of the pile, you only need to know the value of n _max and I _o -I _max , after which the corresponding density n is automatically determined by the value of I _o -I.

 In this case, the time for obtaining a calibration dependence for nine points is 65 minutes, and the time for obtaining and measuring a sample with a limiting density of 8 minutes.

Claims (1)

A METHOD FOR DETERMINING THE DENSITY OF THE PILET COATING obtained by electroflocking is that the material is illuminated with a parallel light beam and the optical transmittance of the pile layer is measured, characterized in that, in order to increase accuracy and reduce labor intensity, the optical transmittance of the pile coating with the maximum allowable density is additionally measured pile, and the density value of the pile is determined by the formula

where n _{m a c s the} density of the pile layer of the sample with the maximum density under the flocking conditions of the pile density;
T _{m and a} pile _with an optical transmittance layer of a sample with a density of _{m and} n _{to s;} T optical transmission of the pile layer of the test sample.

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