CN101294885A - Method for detecting polyvinylidene fluoride content in hot melt type fluor resin coating dry film - Google Patents

Abstract

The invention discloses a method for detecting polyvinylidene fluoride content in a PVDF dry coating film, which comprises the following steps: (1) scraping and selecting a sample; (2) conducting thermogravimetric analysis: weighing the sample correctly, spreading the same on an alumina pattern dish, and conducting the thermogravimetric analysis by using a thermogravimetric analyzer; and (3) processing data: drawing the thermogravimetric analysis (TGA) curve and differential thermogravimetric analysis (DTGA) curve of acrylics and the polyvinylidene fluoride, dividing the TGA curve into two zero-g periods by using two sharp zero-g peaks at the temperature of 350-450 DEG C on the DTGA curve, calculating with formula I, and obtaining the polyvinylidene fluoride content. The detecting method is obviously superior to the prior PVDF content detecting technology, and has the advantages of high accuracy, low pollution, high detecting speed, low requirement for instrument and equipment, low cost, suitability for wide popularization and application, etc.

Description

The detection method of content of polyvinylidene fluoride in the hot melt type fluor resin coating dry film

Technical field

The present invention relates to the detection of building materials, be specifically related to polyvinylidene fluoride in a kind of hot melt type fluor resin coating dry film (PVDF) content detecting method.

Background technology

Structural metal curtain wall field in one of main application places of fluorine resin coating, JG/T133-2000 " aluminium sheet for building, aluminium section bar fluororine-carbon coating ", GB/T 17748-1999 series of standards such as " composited aluminum and plastic deckings " stipulate that all the Side fascia coating should adopt 70% (PVDF content in the coating resin) or the suitable fluorocarbon resin of other performance.Along with the development of fluorine resin coating industry, cross-linking type fluorine resin coating (FEVE) also begins using in pre-roller coat aluminium coiled material, and has passed through in this standard the every technical indicator about coating performance.Up to now, has only fluorocarbon resin coating, just can stand the ordeal of any weather conditions on the earth, and do not lose its true qualities, in addition, it also has Chinese People's Anti-Japanese Military and Political College's gas pollution, the characteristic of oily dirt free dirt, have excellent anti-fading property, chalking resistance, resistance to fouling (as acid rain etc.), ultraviolet light ability and splitting resistance, these advantages all are that conventional coating institute is inaccessiable.

At building field, the content of PVDF in coating resin must be equal to or higher than 70%, only in this way just can guarantee the attractive in appearance for a long time of the quality of fluororine-carbon coating and buildings.The detection method of PVDF resin content is provided in the appendix of HG/T 3793-2005 " fluorine resin coating ", is to utilize the dissolubility of PVDF resin, acryl resin and pigment different, selects for use suitable solvent body that they are separated from one another.Wherein, colorant is insoluble to organic solvent fully, and the PVDF resin is only soluble in N-Methyl pyrrolidone, dimethyl sulfoxide (DMSO), N, dinethylformamide, N, N-dimethyl acetamide equal solvent, polyacrylate also are dissolved in other ordinary organic solvents except that being dissolved in the Kynoar solvent.Promptly earlier carry out centrifuging by different solvents, the mode of weighing with drying is measured the PVDF resin content then.The main error of this method is from the use of insoluble thermal-curable acrylic fat, and in addition, the use of organic toner also can cause error.On the other hand, this method hardly may for the mensuration that is coated with PVDF resin content in the product (as hot melt type fluor resin coating dry film) that installs, wherein Zui Da problem is, from coating, often can only obtain a little sample, generally be no more than 50mg, and it is in the standard said method regulation sample is generally needed 50g, thereby bigger by the operated in accordance with conventional methods error.

Summary of the invention

The invention provides the less method of utilizing thermogravimetric analysis (TGA)-derivative thermogravimetric analysis (DTGA) that polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content is detected of a kind of error.

Detection method provided by the present invention may further comprise the steps:

1) scrapes sample thief;

2) thermogravimetric analysis: sample is accurately weighed, it is divided on aluminium oxide style ware then and carry out thermogravimetric analysis with thermogravimetric analyzer, the control heating rate is 4-6 ℃/min, carrier gas N ₂Flow is 40-60mL/min, and final temperature is 500-700 ℃, heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process;

3) data processing: thermogravimetric analysis (TGA) curve and derivative thermogravimetric analysis (DTGA) curve of drawing acryl resin and polyvinylidene fluoride, utilize on the derivative thermogravimetric analysis curve two sharp-pointed weightless peaks of 350-500 ℃ that the thermogravimetric analysis curve is divided into two zero-g periods, calculate with formula I then, draw polyvinylidene fluoride (PVDF) content:

$C_{\mathrm{PVDF}}=\frac{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}}{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}+{\mathrm{TG}}_{\mathrm{Acrylic}}}\×100\%$ (formula I)

Wherein, C _PVDFExpression PVDF content, TG _PVDFExpression PVDF thermal weight loss amount, TG _AcrylicExpression polyacrylate thermal weight loss amount.

In the detection method of above-mentioned content of polyvinylidene fluoride, the sample in the step 1) is scraped access method and be can be: with blade the hot melt type fluor resin coating on object under test surface is scraped 4-6mg (being preferably 5mg), be strictly on guard against that scraping priming paint is infected with.

Step 2) be accurate to 0.1mg during to samples weighing in, example weight is preferably 5.0mg; Available commercially available any ISO 11358:1997 that meets, the thermogravimetric analyzer of Plastics-Thermogravimetry (TG) of Polymers-Generalprinciples regulation is (as TA Q500, NETZSCH TG209C) sample is carried out thermogravimetric analysis, heating rate is preferably 5 ℃/min, carrier gas N ₂Flow is preferably 50mL/min, and final temperature is preferably 600 ℃.

Available conventional method is drawn thermogravimetric analysis curve and derivative thermogravimetric analysis curve in the step 3).

The present invention detects polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content by thermogravimetric analysis (TGA)-derivative thermogravimetric analysis (DTGA), utilize acryl resin weightlessness 100% under 350 ℃, and PVDF weightlessness 62.5% under 450 ℃, utilize the thermogravimetric curve figure of the two, calculate the content of PVDF in the hot melt type fluor resin coating dry film.Therefore, PVDF detection method of content of the present invention only needs less sample, and have the high and low pollution of accuracy, detection speed fast, to advantages such as the instrument and equipment requirement are low and with low cost, obviously be better than existing P VDF content detection technology, be fit to promotion and application.

Below in conjunction with specific embodiment the present invention is described in further details.

Description of drawings

Fig. 1 is the thermogravimetric curve figure of acryl resin

Fig. 2 is the thermogravimetric curve figure of polyvinylidene fluoride (PVDF)

Fig. 3 is that PVDF content is acryl resin/PVDF thermogravimetric curve figure of 70% in the resin of being prepared

Fig. 4 is PVDF content (Predict) comparison diagram that the sample of known PVDF content (Prepare) records by the inventive method

Embodiment

The invention provides a kind of method of utilizing thermogravimetric analysis (TGA)-derivative thermogravimetric analysis (DTGA) that polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content is detected that realizes by thermogravimetric analyzer and analysis software thereof.The detection principle of this method is: acryl resin anaerobic degradation fully under about 350 ℃, condition of nitrogen gas, and the weight loss theoretical value is 100%, and the reaction (seeing formula II) of dehydrofluorination takes place in PVDF under about 450 ℃, condition of nitrogen gas,

(formula II)

The weight loss theoretical value is 62.5%, utilizes the thermogravimetric curve figure of the two, promptly can calculate the content of PVDF in the hot melt type fluor resin coating dry film.

Method therefor is conventional method if no special instructions among the following embodiment.

The experiment of sample weight-loss curve under embodiment 1, the thermogravimetric condition

With method of the present invention polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content is detected, concrete grammar may further comprise the steps:

1) scrapes sample thief

With blade the surperficial hot melt type fluor resin coating of object under test (aluminium-plastic panel, aluminum veneer, aluminium section bar etc., customer consignment or market sampling observation sample) is scraped about 5mg, be strictly on guard against that scraping priming paint is infected with.

2) thermogravimetric analysis

Accurately take by weighing 5.0mg (being accurate to 0.1mg) sample, then it is divided that the thermogravimetric analyzer with NETZSCHTG209C (meets ISO 11358:1997 on aluminium oxide style ware, Plastics-Thermogravimetry (TG) of polymers-General principles regulation all can) carry out thermogravimetric analysis (TGA), the control instrument heating rate is 5 ℃/min (accurately is controlled in 4-6 ℃/min scope a numerical value all can), carrier gas N ₂Flow is 50mL/min (accurately is controlled in the 40-60mL/min scope numerical value all can), and final temperature is 600 ℃ (accurately are controlled in 500-700 ℃ of scope a numerical value all can), heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process.

3) data processing

Thermogravimetric analyzer is drawn thermogravimetric analysis (TGA) curve and derivative thermogravimetric analysis (DTGA) curve of acryl resin and polyvinylidene fluoride, utilize on the derivative thermogravimetric analysis curve two sharp-pointed weightless peaks of 350-500 ℃ that the thermogravimetric analysis curve is divided into two zero-g periods, calculate with formula I then, can draw polyvinylidene fluoride (PVDF) content:

$C_{\mathrm{PVDF}}=\frac{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}}{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}+{\mathrm{TG}}_{\mathrm{Acrylic}}}\×100\%$ (formula I)

Wherein, C _PVDFExpression PVDF content, TG _PVDFExpression PVDF thermal weight loss amount, TG _AcrylicExpression polyacrylate thermal weight loss amount.

(horizontal ordinate is a temperature to the derivative thermogravimetric analysis of acryl resin (DTGA) curve as shown in Figure 1, ordinate is a weight loss), as seen from Figure 1, acryl resin anaerobic degradation fully under about 350 ℃, condition of nitrogen gas, weight loss is approximately 97% (theoretical value is 100%); (horizontal ordinate is a temperature to the thermogravimetric curve figure of polyvinylidene fluoride (PVDF) as shown in Figure 2, ordinate is a weight loss), as seen from Figure 2, dehydrofluorination takes place in PVDF under 450 ℃, condition of nitrogen gas, and weight loss is approximately 63% (theoretical value is 62.5%).

The detection of polyvinylidene fluoride in embodiment 2, the hot melt type fluor resin coating dry film (PVDF) content

With method of the present invention polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content (70%) is detected, concrete grammar may further comprise the steps:

1) scrapes sample thief and make standard model

(compound method is with reference to CECS231:2007 " aluminium-plastic compound plate curtain engineering construction and control of acceptance " appendix A with the hot melt type fluor resin coating on standard object under test composited aluminum and plastic decking surface with blade, PVDF content is 70%) scrape about 5mg, be strictly on guard against that scraping priming paint is infected with.

2) thermogravimetric analysis

Accurately take by weighing 5.0mg (being accurate to 0.1mg) standard model, then it is divided that the thermogravimetric analyzer with NETZSCH TG209C model (meets ISO 11358:1997 on aluminium oxide style ware, Plastics-Thermogravimetry (TG) of polymers-General principles regulation all can) carry out thermogravimetric analysis (TGA), the control heating rate is 5 ℃/min, carrier gas N ₂Flow is 50mL/min, and final temperature is 600 ℃, heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process.

3) data processing

Draw thermogravimetric analysis (TGA) curve and derivative thermogravimetric analysis (DTGA) curve of acryl resin and polyvinylidene fluoride, utilize on the derivative thermogravimetric analysis curve two sharp-pointed weightless peaks of 350-500 ℃ that the thermogravimetric analysis curve is divided into two zero-g periods, calculate with formula I then, can draw polyvinylidene fluoride (PVDF) content.

The thermogravimetric curve figure of sample as shown in Figure 3, as seen from Figure 3,359-400 ℃ weightlessness is the degraded of acryl resin, weight loss (TG _Acrylic) be 22.33% of sample gross weight, 437-463.5 ℃ weightlessness is the dehydrofluorination of PVDF, weight loss (TG _PVDF) be 32.48% of sample gross weight, the formula I of bringing into calculates the content (C of PVDF _PVDF) be 70.3%, compare with PVDF content in the standard model 70% and be identical, prove that PVDF detection method of content of the present invention has higher accuracy.

The detection of polyvinylidene fluoride in embodiment 3, the hot melt type fluor resin coating dry film (PVDF) content

With method of the present invention polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) content (Prepare, content is known, is respectively 0%, 50%, 60%, 70%, 80%, 90%, 100%) is detected, concrete grammar may further comprise the steps:

1) scrapes sample thief

With blade the surperficial hot melt type fluor resin coating of each object under test (by above-mentioned design content self-control clad plate) is scraped about 4mg, be strictly on guard against that scraping priming paint is infected with.

2) thermogravimetric analysis

Accurately take by weighing 4.0mg (being accurate to 0.1mg) sample, then it is divided that the thermogravimetric analyzer with the NETZSCHTG209C model (meets ISO 11358:1997 on aluminium oxide style ware, Plastics-Thermogravimetry (TG) of polymers-General principles regulation all can) carry out thermogravimetric analysis (TGA), the control heating rate is 4 ℃/min, carrier gas N ₂Flow is 40mL/min, and final temperature is 500 ℃, heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process.

3) data processing

Draw thermogravimetric analysis (TGA) curve and derivative thermogravimetric analysis (DTGA) curve of acryl resin and polyvinylidene fluoride respectively, utilize on the derivative thermogravimetric analysis curve two sharp-pointed weightless peaks of 350-500 ℃ that the thermogravimetric analysis curve is divided into two zero-g periods, calculate with formula I then, can draw polyvinylidene fluoride (PVDF) content.

The sample of known PVDF content (Prepare) is as shown in table 1 by the PVDF content (Predict) that the inventive method records, and comparison diagram as shown in Figure 4.

Content (predict) correlation data that the sample of the known PVDF content of table 1 (prepare) records by this method

Formulation content (Prepare), %	Record content (Predict), %
		100	100.9
90	89.3
		80	80.6
70	70.3
		60	59.4
50	49.2
		0	0

By table 1 and Fig. 4 as can be seen, the inventive method is very approaching to actual detected value and the theoretical value of PVDF, and the content that can determine polyvinylidene fluoride in the hot melt type fluor resin coating dry film (PVDF) with method of the present invention comparatively exactly is described.

Claims (9)

1, the detection method of content of polyvinylidene fluoride in the hot melt type fluor resin coating dry film, it is characterized in that, collected specimens is carried out thermogravimetric analysis, draw thermogravimetric analysis (TGA) curve and derivative thermogravimetric analysis (DTGA) curve, utilize on the differential thermogravimetric curve two sharp-pointed weightless peaks of 350-500 ℃ that the thermogravimetric analysis curve is divided into two zero-g periods, calculate with formula I then, can draw polyvinylidene fluoride (PVDF) content:

$C_{\mathrm{PVDF}}=\frac{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}}{\frac{{\mathrm{TG}}_{\mathrm{PVDF}}}{62.5\%}+{\mathrm{TG}}_{\mathrm{Acrylic}}}\×100\%$ (formula I)

Wherein, C _PVDFExpression PVDF content, TG _PVDFExpression PVDF thermal weight loss amount, TG _AcrylicExpression polyacrylate thermal weight loss amount.

2, detection method according to claim 1 is characterized in that: described collected specimens is got for scraping from hot melt type fluor resin coating dry film.

3, detection method according to claim 1 is characterized in that: described sample is scraped access method and is: with blade the hot melt type fluor resin coating on object under test surface is scraped 4.0-6.0mg.

4, detection method according to claim 3 is characterized in that: the described example weight of getting of scraping is 5.0mg.

5, detection method according to claim 1 is characterized in that: in the described thermogravimetric analysis sample and weightless weighing thereof are accurate to 0.1mg.

6, according to claim 1 or 2 or 3 or 4 or 5 described detection methods, it is characterized in that: described gravitational thermal analysis method is: sample is accurately weighed, it is divided on aluminium oxide style ware then and carry out thermogravimetric analysis with thermogravimetric analyzer, the control heating rate is a numerical value in the 4-6 ℃/min scope, carrier gas N ₂Flow is a numerical value in the 40-60mL/min scope, and final temperature is a numerical value in the 550-650 ℃ of scope, heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process.

7, detection method according to claim 6, it is characterized in that: with meeting ISO 11358:1997, the thermogravimetric analyzer of Plastics-Thermogravimetry (TG) of polymers-General principles regulation carries out thermogravimetric analysis to sample.

8, according to claim 6 or 7 described detection methods, it is characterized in that: heating rate is 5 ℃/min, carrier gas N ₂Flow is 50mL/min, and final temperature is 600 ℃.

9, according to the described detection method of arbitrary aforementioned claim, it is characterized in that, may further comprise the steps:

1) scrapes and get the 4.0-6.0mg sample;

2) thermogravimetric analysis: sample is accurately weighed, it is divided on aluminium oxide style ware then and carry out thermogravimetric analysis with thermogravimetric analyzer, the control heating rate is a numerical value in the 4-6 ℃/min scope, carrier gas N ₂Flow is a numerical value in the 40-60mL/min scope, and final temperature is a numerical value in the 550-650 ℃ of scope, heating rate, carrier gas N ₂It is constant that flow and final temperature keep in testing process;

3) acryl resin that obtains data processing: utilize step 2) and the thermogravimetric analysis curve and the derivative thermogravimetric analysis curve of polyvinylidene fluoride calculate content of polyvinylidene fluoride.

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