CN101672774A - Method for quickly measuring content of polyvinylidene fluoride in fluorine-carbon paint of chromatic coating steel plate by infrared spectrum method - Google Patents

Abstract

The invention relates to a method for measuring the content of polyvinylidene fluoride (PVDF) in the fluorine-carbon paint of a chromatic coating steel plate by an infrared spectrum method. The methodselects the absorption peak of the PVDF in a wave band of 894-863cm<-1> and the absorption peak of acrylic resin in a wave band of 1764-1696cm<-1>, takes a Lambert-Bill law as a theoretical basis, calculates peak areas respectively, establishes a linear relational expression model of the content ratio and the peak area ratio of the PVDF and acrylate and obtains the content of the PVDF in an unknown sample directly by calculating the peak area of a corresponding base group of an infrared spectrogram of the unknown sample. Compared with the traditional method, the method is rapid, simple and quick, enhances the analysis efficiency, lowers the analysis cost and has strong practicability.

Description

The method of content of polyvinylidene fluoride in the infra-red sepectrometry fast measuring fluorine-carbon paint of chromatic coating steel plate

Technical field

The present invention is a kind of method of utilizing polyvinylidene fluoride in the infrared spectroscopic determination fluorine-carbon paint of chromatic coating steel plate (PVDF) content.

Background technology

Along with science and technology, fast development of social economy, iron and steel manufacturing technology and product make rapid progress, outward appearance is beautiful, corrosion stability good, easy machine-shaping, long service life, pollution less, the color coated steel sheet of function practicality come into our life, and has been widely used in every field such as building industry, transportation, household electrical appliance, furniture and office accommodations.The coating of color coated steel sheet has a variety of, and wherein fluorocarbon coating is owing to contain a large amount of C-F keys in the resin, and its exterior durability, acidproof rain and aspects such as anti-atmospheric pollution, corrosion resistance, print resistance and fungus resistance have better comprehensive performance.

At present, the fluorine-carbon paint of chromatic coating steel plate of industrial use mainly is acryl resin/PVDF system.The performance of the content of fluorine and coating is closely related in this system, and fluorine content directly determines the quality and the performance of coating.The domestic so far examination criteria that does not also have fluorine content in the unified fluorocarbon coating, the method for traditional mensuration PVDF content must be obtained a result as calculated through separating, measuring content of fluoride ion after dry, the decomposition and inversion, and complex process, test period are long.Set up a kind of method of measuring PVDF content in the coating fast and accurately and have realistic meaning.

Summary of the invention

The object of the present invention is to provide a kind of method that adopts polyvinylidene fluoride PVDF content in the infrared spectroscopic determination fluorine-carbon paint of chromatic coating steel plate.

Not isoplastic diffuse reflectance infrared spectroscopy peak position difference, in the infrared spectrogram of polyvinylidene fluoride PVDF at 1404cm ^-1, 1190cm ^-1, 1075cm ^-1And 882cm ^-1The characteristic absorption peak of the C-F key chattering of polyvinylidene fluoride PVDF appears in the place; The infrared spectrogram of acryl resin is at 1730cm ^-1About the characteristic absorption peak of ester carbonyl group appears, at 1250cm ^-1-1100cm ^-1The characteristic absorption peak that the acryl resin ehter bond occurs.Polyvinylidene fluoride PVDF is at 894-863cm ^-1The absorption peak of wave band does not have mutual interference mutually with acryl resin, and acryl resin is at 1730cm ^-1About absorption peak do not have mutual interference mutually with polyvinylidene fluoride PVDF yet.So selected wave-number range is 894-863cm ^-1With 1764-1696cm ^-1Peak respectively quantitative polyvinylidene fluoride PVDF and acryl resin content.

1) according to Beer law A=abc

A is an absorbance, and a is an absorptivity, and b is a thickness of sample, and c is the concentration of absorbing material.Promptly when a branch of collimated monochromatic ligth vertically during the extinction material by a certain even non-scattering, its absorbance A is directly proportional with the concentration c and the absorber thickness b of extinction material.And the peak area of infrared spectrum is directly proportional with absorbance A, i.e. peak area S ∝ absorbance A.So:

$\frac{S_1}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}=\frac{A_1}{{\mathrm{<figure-callout\; id="2"\; label="A"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">A</figure-callout>}}_2}=\frac{a_{1}b{c}_1}{a_2\mathrm{<figure-callout\; id="2"\; label="b\; c"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">b</figure-callout>}{c}_{}{}_2}=\frac{a_1{c}_1}{a_2{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">c</figure-callout>}}_2}=\frac{a_1}{a_2}*\frac{w_1/{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">m</figure-callout>}}_1/V}{w_2/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="A2009101965280008H1.png"\; state="\{\{state\}\}">m</figure-callout>}}_2/V}=K\frac{w_1}{w_2}$

Wherein, S ₁For polyvinylidene fluoride PVDF at 894-863cm ^-1The absorption peak area of wave band, S ₂For acryl resin at 1764-1696cm ^-1The absorption peak area of wave band; a ₁For polyvinylidene fluoride PVDF at 894-863cm ^-1Absorptivity in the scope, a ₂For acryl resin at 1764-1696cm ^-1Absorptivity in the scope; w ₁Be the quality of polyvinylidene fluoride PVDF, w ₂Quality for acryl resin; m ₁Be the molal weight of polyvinylidene fluoride PVDF, m ₂Molal weight for acryl resin; V is a sample volume; K is a constant.

As can be seen from the above equation, peak area ratio and concentration ratio are proportional.

2) regression analysis

Regression straight line can be used following The Representation Equation

y＝p+qx

In the formula, p is the intercept of straight line, and q is the slope of straight line.

P, the calculating formula of q is respectively

$p=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{y}_i-q\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{x}_i}{n}=\stackrel{\&OverBar;}{y}-q\stackrel{\&OverBar;}{x}$ $q=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(x_i-\stackrel{\&OverBar;}{x})(y_i-\stackrel{\&OverBar;}{y})}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-\stackrel{\&OverBar;}{x})}^2}$

In the formula, x, y are respectively the mean value of x and y, work as p, and after q determined, linear work curve and equation of linear regression had just been determined.

Regression straight line whether check by meaningful available coefficient R.The definition of related coefficient is

$R=q\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-\stackrel{\&OverBar;}{x})}^2}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(y_i-\stackrel{\&OverBar;}{y})}^2}}=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(x_i-\stackrel{\&OverBar;}{x})(y_i-\stackrel{\&OverBar;}{y})}{\sqrt{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-\stackrel{\&OverBar;}{x})}^2\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(y_i-\stackrel{\&OverBar;}{y})}^2}}$

The physical significance of related coefficient is as follows:

A.R ²=1 o'clock, represent to have linear relationship completely between two variablees;

B.R ²=0 o'clock, represent not have linear relationship between two variablees;

C.R ²0 between 1 the time, represent to have correlationship between two variablees.

So, R ²Value is more near 1, and linear pass is good more.

According to above-mentioned mechanism, the present invention adopts following technical scheme:

The method of content of polyvinylidene fluoride in a kind of infrared spectroscopic determination fluorine-carbon paint of chromatic coating steel plate is characterized in that the concrete steps of this method are as follows:

A. dispose the sample of a series of known content of polyvinylidene fluoride with polyvinylidene fluoride resin and pure acrylic resin, recording each sample is 400-4000cm in wave number ^-1Between infrared absorpting light spectra;

B. 894-863cm in the infrared absorpting light spectra of calculation procedure a gained respectively ^-1Wave band absorption peak and 1764-1696cm ^-1The wave band absorption peak carries out the peak area integration, and polyvinylidene fluoride resin in the ratio of this two peak areas integrated value and the sample is carried out the linear regression simulation with acryl resin content ratio, draws linear work curve and equation of linear regression;

C. measure testing sample 400-4000cm ^-1Between infrared absorpting light spectra, calculate 894-863cm ^-1Wave band absorption peak and 1764-1696cm ^-1The peak area integration of wave band absorption peak draws the ratio of two peak area integrated values, and substitution step b gained equation of linear regression draws the content of polyvinylidene fluoride of testing sample.

The inventive method employing comparatively easy infrared spectrum on measuring is set up the linear relation of PVDF content in the fluorine-carbon paint of chromatic coating steel plate, can finish collection fast to the unknown sample infrared spectrum, and obtain the content of its PVDF, and improve the analysis efficiency of measuring greatly, reduce analysis cost.Method of testing of the present invention is rapid, simple and direct, and data are accurate.

Description of drawings

Fig. 1 is the infrared spectrogram of pure acrylic resin.

Fig. 2 is the infrared spectrogram of pure PVDF sample.

Fig. 3 is the linear work curve map, and promptly the PVDF resin is at 894-863cm ^-1The absorption peak of wave band and acrylate resin are at 1764-1696cm ^-1The ratio of wave band absorption peak peak area compares graph of a relation with PVDF, acryl resin content.

Embodiment

The inventive method employing comparatively easy middle infrared spectrum on measuring is set up the linear relation of PVDF content in the fluorine-carbon paint of chromatic coating steel plate, below in conjunction with accompanying drawing and enforcement the present invention is described in further detail:

Embodiment one: prepare the coating sample of a series of known PVDF content with PVDF resin and pure acrylic resin, through applying after film forming solidifies, record the infrared absorpting light spectra of various samples with Fourier transform infrared spectrometer.By to 894-863cm ^-1Wave band absorption peak and 1764-1696cm ^-1The wave band absorption peak carries out the peak area integration, and the corresponding data that draws is listed in table 1.Ratio with peak area is a horizontal ordinate, and PVDF is ordinate with acryl resin content ratio, and normalized draws linear work curve and equation of linear regression.

Table 1

Sample	PVDF content	PVDF and acrylate content are than (y=w 1/w 2)	?1764-1696cm -1The peak area integration	?894-863cm -1The peak area integration	Peak area integration ratio (x=S 1/S 2)
						??1	??10％	??0.111	?1.34	?0.00500	??0.00373
??2	??30％	??0.429	?1.27	?0.122	??0.0959
						??3	??50％	??1.00	?1.12	?0.299	??0.266
??4	??70％	??2.33	?0.719	?0.515	??0.716
						??5	??80％	??4.00	?0.570	?0.682	??1.20

With x is horizontal ordinate, and y is the ordinate mapping, obtains the linear regression curve as shown in Figure 3, and the gained linear relation is y=3.22x+0.107, and linear regression coeffficient is 0.999, content=w of PVDF ₁/ (w ₁+ w ₂)=1/ (1+w ₂/ w ₁)=1/ (1+y ^-1), this formula of characteristic peak area ratio substitution of the testing sample of PVDF content the unknown can be drawn PVDF content.

Embodiment two: below by example explanation the present invention, but the invention is not restricted to this.Sample is chosen the known color coated steel sheet of certain steel plant's PVDF content, adopt the Nicolet380 mid-infrared light spectrometer of U.S. Nicolet company, after attenuated total reflection (ATR) annex records the infrared spectrogram of color coated steel sheet, calculate the peak area and the ratio thereof of characteristic peak, draw the content of PVDF in the testing sample by the linear relation of having set up, the result is as shown in table 2.

Table 2

Sample	Reel number	Color	Producer	?1764-1696cm -1The peak area integration	?894-863cm -1The peak area integration	Peak area integration ratio	PVDF and acrylic acid content ratio	Measurement result	Actual content
										??1	??379xxx301	Brass	Bei Ge	?0.206	?0.244	??1.18	??3.92	??79.7％	??80％
??2	??379xxx201	Oyster is white	Bei Ge	?0.257	?0.203	??0.79 ??0	??2.65	??72.6％	??73％

From the checking result as can be seen, the method gained linear relation can be measured the content of PVDF in the PVDF coating fast, quickly and easily.

Choose color coated steel sheet (sample 1 and sample 2) of certain PVDF of steel plant content the unknown and the coating (sample 3 and sample 4) that certain coating factory gives certain steel plant.Adopt the Nicolet380 mid-infrared light spectrometer of U.S. Nicolet company, after attenuated total reflection (ATR) annex records the infrared spectrogram of color coated steel sheet, calculate the peak area and the ratio thereof of characteristic peak, draw the content of PVDF in the testing sample by the linear relation of having set up, the result is as shown in table 3.

Table 3

Sample	Reel number	Color	Producer	?1764-1696cm -1The peak area integration	?894-863cm -1The peak area integration	Peak area integration ratio	PVDF and acrylic acid content ratio	Measurement result
									??1	??173xxx501	Brass	The A of producer	?0.277	?0.243	??0.877	??2.93	??74.6％
??2	??378xxx301	Oyster is white	The A of producer	?0.402	?0.143	??0.356	??1.25	??55.6％
									??3	??/	White	The B of producer	?0.812	?0.386	??0.476	??1.64	??62.1％
??4	??/	White	The A of producer	?0.525	?0.299	??0.570	??1.94	??66.0％

Claims (1)

1, the method for content of polyvinylidene fluoride in a kind of infrared spectroscopic determination fluorine-carbon paint of chromatic coating steel plate is characterized in that the concrete steps of this method are as follows:

A. dispose the sample of a series of known content of polyvinylidene fluoride with polyvinylidene fluoride resin and pure acrylic resin, recording each sample is 400-4000cm in wave number ^-1Between infrared absorpting light spectra;

B. 894-863cm in the infrared absorpting light spectra of calculation procedure a gained respectively ^-1Wave band absorption peak and 1764-1696cm ^-1The wave band absorption peak carries out the peak area integration, and polyvinylidene fluoride resin in the ratio of this two peak areas integrated value and the sample is carried out the linear regression simulation with acryl resin content ratio, draws linear work curve and equation of linear regression;

C. measure testing sample 400-4000cm ^-1Between infrared absorpting light spectra, calculate 894-863cm ^-1Wave band absorption peak and 1764-1696cm ^-1The peak area integration of wave band absorption peak draws the ratio of two peak area integrated values, and substitution step b gained equation of linear regression draws the content of polyvinylidene fluoride of testing sample.

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