CN114518302A - Method for determining a rheological parameter of a fluid - Google Patents

Method for determining a rheological parameter of a fluid Download PDF

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CN114518302A
CN114518302A CN202011311747.0A CN202011311747A CN114518302A CN 114518302 A CN114518302 A CN 114518302A CN 202011311747 A CN202011311747 A CN 202011311747A CN 114518302 A CN114518302 A CN 114518302A
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viscosity
shear rate
paint
measured
coating
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朱敏德
夏天渊
许建华
印维坚
毛方桂
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Nippon Paint China Co Ltd
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Nippon Paint China Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16C—COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
    • G16C60/00—Computational materials science, i.e. ICT specially adapted for investigating the physical or chemical properties of materials or phenomena associated with their design, synthesis, processing, characterisation or utilisation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
    • G01N2011/0026—Investigating specific flow properties of non-Newtonian fluids
    • G01N2011/0033—Yield stress; Residual stress at zero shear rate
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/08—Fluids
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Abstract

The invention discloses a method for determining rheological parameters of a fluid, comprising the steps of: preparing a paint sample, diluting the paint to construction conditions, simulating the shear rate of the paint sample during spraying, and testing the viscosity; then testing the viscosity at each different shear rate, and finally fitting a suitable model with the measured viscosity based on iterative fitting of the model to obtain the yield stress of the paint sample. The method can predict the rheological behavior of the coating in construction, and effectively avoids the adverse defects of sagging, orange peel and the like of the coating on site.

Description

Method for determining rheological parameters of a fluid
Technical Field
The invention belongs to a rheological detection method of a coating, and relates to a method for determining rheological parameters of a fluid, in particular to a detection method of rheological property of the coating.
Background
The property of a liquid that undergoes irreversible deformation when subjected to stress is called the rheology of the liquid. Rheology is one of the important properties exhibited by coatings during production, storage and application and directly affects the quality and performance of the dry film of the coating. While viscosity (usually in pascal seconds Pa · S) is an important indicator of paint rheology. The coating material flows parallel to each other with a certain velocity difference under the action of shear force, the force applied per unit area is called shear force, the velocity gradient is called shear rate, and the ratio of shear force to shear rate is called viscosity, which is a measure for the resistance of the liquid to flow.
The coating is generally a non-newtonian fluid with a large pseudoplasticity and no linear relationship between viscosity and shear rate. The viscosity of the coating showed a very rapid decrease with increasing shear rate. If the viscosity of the coating is too high, the leveling property is poor, pockmarks or rough textures like orange peels are easy to appear on a paint film, and the surface of the coating is wrinkled or orange peel-shaped uneven. If the viscosity of the coating is too low, in the case of applying a coating method such as dipping, pouring, spraying, brushing, etc., the coating is easily solidified as it is and firmly attached after being accumulated on the vertical surface and the vicinity of the edge of the object to be coated, and this is called sagging. Therefore, in applications with high requirements for coating (such as automotive coatings), it is necessary to predict the viscosity and rheological properties of the coating more accurately, so as to better determine whether the coating is prone to sagging or orange peel when used on site.
In the prior art, the traditional paint viscosity detection methods such as a viscosity cup and a rotational viscometer are generally adopted, accurate measurement and prediction cannot be achieved, and the risk of paint film defects of the paint in the coating construction process is still high. After the defects of a paint film occur, the coating line needs to be stopped or reworked, and larger economic loss is brought.
In view of the above, there is a need in the art for a method capable of determining viscosity and rheological parameters of a fluid, so as to help accurately predict whether undesirable phenomena such as sagging or orange peel may occur during field use.
Disclosure of Invention
In order to overcome the technical problems, the invention provides a method for determining rheological parameters of fluid, thereby providing a simple and feasible rheological detection method for paint and related raw materials, and effectively avoiding the adverse phenomena of sagging, orange peel and the like during most on-site coating.
The invention provides a method for determining a rheological parameter of a fluid, comprising the following steps in sequence: :
(1) preparing a paint sample, diluting the paint to construction conditions, simulating the shear rate of the paint sample during spraying, and testing viscosity;
(2) viscosity was measured and the shear rate of the simulated paint samples was less than 0.2 to 0.3s-1；
(3) Viscosity was measured and the shear rate of the simulated paint samples was less than 0.4 to 0.6s-1；
(4) Viscosity was measured and the shear rate of the simulated paint samples was less than 0.7 to 0.9s-1；
(5) Viscosity was measured and the shear rate of the simulated paint samples was 1.0 to 1.2s-1；
(6) Viscosity was measured and the shear rate of the simulated paint samples was 1.4 to 1.6s-1；
(7) Viscosity was measured and the shear rate of the simulated paint samples was 1.8 to 2.2s-1；
(8) Viscosity was measured and the shear rate of the simulated paint samples was 2.8 to 3.2s-1；
(9) Viscosity was measured and the shear rate of the simulated paint sample was 4.0 to 5.0s-1；
(10) An appropriate model is fitted to a measured viscosity based on iterative fitting of the model to obtain the yield stress of the paint sample.
Further, the shear rate in step (1) is 500 to 1000s-1。
Further, the model used was the Herschel-Bulkey model.
Further, the power function of the model is
Figure BDA0002790035930000021
Wherein k is the viscosity coefficient (Pa S)n) N is the flow index, η is the viscosity (Pa s),
Figure BDA0002790035930000022
is the shear rate(s)-1)，τ0Yield stress (Pa).
Further, in the model, the shear rate of the steps (2) to (8) is X-axis, and the viscosity is Y-axis.
Further, the viscosity was measured at a temperature of 23 ± 0.5 ℃.
Further, the standard for judging whether the fluid is qualified is that the yield stress of the solvent type varnish is 0.95 +/-0.05 Pa, and the yield stress of the water-based colored paint is 0.55 +/-0.05 Pa.
Further, for solvent-based varnishes, the working conditions were 23 ℃ working viscosity paint-4 cups for 25-40 seconds.
Further, for aqueous paints, the application conditions are a viscometer type B at 6rpm, with a viscosity of 1000 to 7000mPa s.
Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:
1. the method of the invention obtains the yield stress of the coating at the leveling time through regression analysis from the simple and easily obtained data by testing the viscosity at different shear rates. By analyzing the numerical range of the yield stress, the sagging and leveling of the coating on site are better balanced, and the better coating appearance is ensured.
2. According to the obtained numerical range of the yield stress, the most appropriate construction condition of the coating can be confirmed, the formula design and optimization can be guided, and the leveling and sagging properties of the coating are ensured to be in the optimal state, so that the performance of the coating in actual spraying is predicted.
3. The method of the invention can not only be used in coating products, but also be used for detecting the rheological property of similar materials, especially rheological resin and other materials, and can be used as a strong and stable control means to realize the best effect.
4. The Herschel-Bulkey rheological mathematical model is innovatively applied to the traditional field of the paint for the first time, the appearance and the construction performance of the paint during coating application are accurately, stably and universally predicted through conventional and easily-obtained viscosity data, a large number of repeated paint manufacturing and coating experiments are reduced, the economic benefit is improved, and the negative influence of the paint on the environment is reduced.
Drawings
Figure 1 shows a schematic of painting on perforated steel panels using a three coat two bake process.
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention should be understood not to be limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known techniques or other techniques having the same functions as those of the known techniques.
In the following description of the specific embodiments, it is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the invention and to simplify the description, but are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically stated otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be in communication within two elements or in interactive relationship between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Unless clearly indicated to the contrary, each aspect or embodiment defined herein may be combined with any other aspect or embodiments. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.
In the present invention, the software for fitting the Hershel-Bulkey mathematical rheological model includes, but is not limited to, MATLAB (MathWorks, USA), Origin (Origin Lab, USA), MiniTab (Minitab, USA), Excel (Microsoft, USA), etc.
Example 1: confirming a suitable construction viscosity of the automotive finishing varnish:
the method comprises the following steps: varnish a, varnish b, varnish c, varnish d and varnish e were prepared according to the formulations (parts by weight) shown in table 1 below.
TABLE 1 formulation of varnishes a to e in example 1
Figure BDA0002790035930000041
Figure BDA0002790035930000051
The preparation method comprises the following steps:
1) adding ethylene glycol butyl ether acetate, mixed dibasic acid dibasic ester (DBE), 3-Ethoxy Ethyl Propionate (EEP) and butyl acetate into the main cylinder a in sequence, and stirring for 10 minutes at the rotating speed of 200-400 rpm;
2) sequentially adding TINUVIN 292, TINUVIN 384-2, BYK358N and BYK 310 into a master cylinder a at the rotating speed of 300 plus 500rpm, and continuously stirring for 30 minutes after the addition is finished;
3) adding n-butanol into the auxiliary cylinder b, then adding AAC 2500 under the constant stirring of 200-400rpm, and continuing stirring for 15 minutes; adding the mixture in the secondary cylinder b into the main cylinder a under the stirring state of the main cylinder a at 300-;
4) sequentially adding Desmodur BL 3175A and ETERAC 7393-S-80 into the main cylinder a at the rotating speed of 300-500rpm, and continuing stirring for 20 minutes after the addition is finished;
5) sequentially adding SETALUX 91796SS-69 and SETALUX91772SS-60 into the main cylinder a at the rotating speed of 300-500rpm, and continuing stirring for 30 minutes after the addition is finished;
6) at the rotation speed of 300-500rpm, SETAMINE US-138BB-70 is added into the master cylinder a in sequence,
Figure BDA0002790035930000052
NF 2000A, and continuing to stir for 30 minutes after the addition is finished;
7) adding DURANOL T5650E into the master cylinder a at the rotating speed of 300-;
8) the varnishes in master cylinder a were diluted to the appropriate viscosities described in table 1 using the appropriate amounts of n-butanol and DBE to give the varnishes a, b, c, d and e.
The viscosity was measured using an MCR high-level rotational rheometer (available from Antopa corporation):
the method comprises the following steps: the viscosity was tested to simulate the change in viscosity when sprayed. The temperature of the equipment is set to be 23 ℃, and the shear rate is 500-1000 s-1The detection time is 30-150 s. The data were measured every 1s and averaged to simulate the viscosity change as sprayed.
Step two: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 0.2-0.3 s-1The detection time is 10-20 s. One data is tested every 1s, an average value is taken, and the viscosity recovery during flowing time after spraying is simulated.
Step three: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 0.4-0.6s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step four: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 0.7-0.9 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step five: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 1.0-1.2 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step six: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 1.4-1.6 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step seven: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is 1.8-2.2 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step eight: the viscosity was tested to simulate viscosity change upon flow. The setting temperature is 23 ℃, and the shear rate is 2.8-3.2 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step nine: the viscosity was tested to simulate viscosity change upon flow. The temperature of the equipment is set to be 23 ℃, and the shear rate is set to be 4-5 s-1The detection time is 10-20 s. The data is tested every 1s, the average value is taken, and the viscosity recovery during flowing and leveling is simulated after spraying.
Step ten: and (4) obtaining a curve by taking the shear rate as an X axis and the viscosity as a Y axis according to the data obtained in the second step to the ninth step. And performing exponential function fitting by using Herschel-Bulkey to obtain the yield stress of the coating at the flat state. The results are shown in table 2 below.
Step eleven: an electrodeposition coating PN-310 (cationic electrodeposition coating, commercially available from Stand-alone paint) was applied to a zinc phosphate-treated passivated steel sheet until the dry coating film thickness reached 20 μm, and then the steel sheet was cured by heating at 160 ℃ for 30 minutes and then cooling to form a cured electrodeposition coating film. And then, spraying the prepared finishing varnish on the electrophoretic coating by adopting a three-coating and two-baking process. The other coatings involved are shown in table 3 below.
The three-coating two-baking process is briefly described as follows: applying a primer or basecoat to a substrate and curing it, applying a basecoat to said substrate with the basecoat or basecoat having been cured, applying said clearcoat composition to the uncured basecoat surface, and simultaneously curing both coats to obtain said multi-coat finish system, said multi-coat finish system being a three coat two bake system.
Table 3 formulation and application conditions for each coating used in the three coat two bake process of example 1
Figure BDA0002790035930000061
Step twelve, using a Byk orange peel instrument WaveScan to test the appearance of each varnish, wherein the appearance comprises Lw long wave, Sw short wave and DOI distinctness of image values; each panel was tested three times and the average was taken. The results are described in table 2 above.
And step thirteen, coating the perforated steel plate shown in the figure 1 by using the three-coating two-baking process. And (5) performing normal spraying by using the same intermediate coating and color paint as the step eleven. When the varnish is sprayed, the spraying direction is from right to left, the traveling speed of the spray gun is changed from slow to fast, and therefore a coating with the thickness from thick to thin is formed. And measuring the film thickness of the composite coating at the position of 0.5cm from the sagging to the lower edge of the round hole as the sagging limit film thickness of the coating. The results are shown in Table 2.
Table 2 test results for each varnish in example 1
Figure BDA0002790035930000071
As can be seen from Table 2, the yield stress of varnish b and varnish c is in the range of 0.9-1.1 Pa, and the appearance and sag limit are both better. The yield stress of the varnish a is slightly higher, the fluidity of the varnish is slightly poor within a period of time after coating, and the varnish shows better sagging limit, slightly poor appearance and long wave/short wave data. The viscosity of varnish d is slightly lower than that of varnish c, but the yield stress is greatly reduced, and it can be seen that the yield stress and the viscosity do not show a linear relationship. As a result, varnish d exhibits a better appearance with a slightly lower sag limit, which poses a certain risk to the actual on-site automotive painting. The varnish e has no yield stress, namely the coating basically loses pseudoplasticity, and can generate larger flow under the environment of extremely small stress, so that the extreme sagging limit is caused, and the varnish e cannot be applied in site coating.
Therefore, the actual appearance and the workability of the coating during coating can be predicted by the yield stress value of the coating obtained by the method.
Example 2: determining a suitable formulation for automotive overprint varnishes
Varnish c, varnish c1, varnish c2, varnish c3, varnish c4 and varnish c5 were prepared in the same manner as used in example 1. Except for the amount of rheological resins SETALUX 91796SS-69 and SETALUX91772SS-60 used in the formulation. The amounts used are detailed in table 4.
Table 4 varnish formulations in example 2
Figure BDA0002790035930000081
Figure BDA0002790035930000091
The varnish coatings in example 2 were each subjected to yield stress, appearance, sagging and the like tests by the same procedure as in example 1. The results are shown in Table 5.
Table 5 results of the varnish tests in example 2
Figure BDA0002790035930000092
Comparing the data in table 5, the yield stress increases gradually as the amount of rheological resin is increased. However, when the amount of the rheological resin is increased further than that of varnish c, the increase in the interaction force such as hydrogen bonds between the resins begins to be slow, the increase in yield stress becomes slow, and the increase in sag limit of varnish c1 and varnish c2 is not significant. The rheological resins of varnish c3 and varnish c4 were used in insufficient amounts, increasing the amount in this range, and the yield stress and sag limit were increased more rapidly. For example, the varnish c5 has no yield stress and lower sagging limit when no rheological resin is used in the formula, and cannot meet the coating requirements of a client on site.
Example 3: pre-inspection of the quality of overprint varnish coatings
According to the formulation of varnish c as in example 1, except for the different batches of SETALUX 91796SS-69 and SETALUX91772SS-60, which themselves have different yield stresses, varnishes f to j were prepared and tested for yield stress, as shown in Table 6, theoretically requiring a yield stress of 0.95. + -. 0.05 Pa.
TABLE 6 varnish for each batch in example 3
Figure BDA0002790035930000101
The above varnishes f to j were subjected to the tests for appearance and sag limit in the same manner as in example 1. The yield stress of both varnish i and varnish j batches failed. The yield stress of varnish i is too low, which leads to a lower sagging limit and, when used in automotive coatings, causes slight film defects of sagging in areas such as body corners. The sag limit of varnish j is much lower and if provided for field use would result in severe varnish appearance and sag problems. Therefore, by adopting the method, the abnormity of the varnish can be effectively predicted in time before the varnish is formally provided for users, and the quality problem of field coating is avoided.
Also in this example, the larger cause of yield stress anomaly is the larger fluctuation in yield stress of the SETALUX 91796SS-69 and SETALUX91772SS-60 rheological resins. Both the two resins are polyurea structures, and the production process is complex. Due to the semi-crystalline microstructure, larger intermolecular forces are generated, so that the coating system has better thixotropy and yield stress. However, when this type of product is produced, the quality of the final product is often unstable due to fluctuations of various factors, and there is a certain probability of defective products. The quality problem of the raw materials is difficult to find by conventional detection means such as viscosity, solid content and the like. As described above, by the inspection method of the present invention, a problem of concealment of raw materials, particularly core raw materials, can be found.
Example 4: optimized aqueous coating formulation
The method of the invention can be used as an effective testing means in the aspects of formulation optimization, production quality control and the like of the water-based paint.
Each of the colored paints was produced according to the formulation shown in Table 7, by carrying out the following steps.
The first step is as follows: adding Aluminum PASTE LX-318S and A-903K-SP into auxiliary jar a, adding ethylene glycol isophorous ether and isophorous alcohol, dissolving, and stirring for 10 min; then adding ACS-1016, Surfynol-440, BYK-345 and DISPERBYK-182 in sequence, and stirring for 20min to obtain a mixture.
The second step is that: sequentially adding DAOTAN VTW 6462/36WA, NP-6100 and CYMEL 250 into the master cylinder b, and stirring for 30 min; and sequentially adding CYMEL 370N, BYK-011, stirring for 15min, and adjusting pH to 7.8-8.5 with 10% aqueous solution of dimethylethanolamine.
The third step: sequentially adding Luhydran S938T and ADEKANOL UH-814N into the master cylinder b, and stirring for 30 min; then, ACW-1011 and AR-2000(T) G314/BF-21PASTE UDP were added in this order and stirred for 20 min.
The fourth step: adding the mixture in the auxiliary cylinder a into the main cylinder b while stirring, washing the auxiliary cylinder a with glycol isophorous ether, merging the washing liquid into the main cylinder b, and stirring for 15 min.
The fifth step: adding pure water, RHEOVIS AS 1130 adjuvant, ethylene glycol monobutyl ether, and 10% aqueous solution of dimethylethanolamine into the main cylinder b while stirring, and stirring for 30 min.
And a sixth step: adjusting the pH value to 7.8-8.5 by using a 10% aqueous solution of dimethylethanolamine; and regulating the viscosity of the B-type paint to be 3000-4500 at 6rpm by using pure water to obtain the water-based colored paint.
TABLE 7 lacquers of the various colors of example 4
Figure BDA0002790035930000111
Figure BDA0002790035930000121
Figure BDA0002790035930000131
Spray tests were performed on yield stress, workability, appearance, etc. of the different water-borne paints as in example 1. Under different rotor viscosities, the water-based colored paints 1-4 show different yield stresses. Unlike varnish, the coating film thickness of the water-based colored paint is 15-17 μm, and the optimal point for balancing the yield stress of the appearance and sagging is 0.55 +/-0.05 Pa. It is noted, however, that in example 1, the yield stress is not completely proportional to the viscosity cup. In example 4, the aqueous paints 5 to 8 showed more remarkable results, and the yield stress showed a large difference even when the rotor viscosity was within a small range of 4000 to 4500 mPas when the amount of the aqueous thickener ADEKANOL UH-814N was different. The yield stress measured by the method is used for predicting the leveling, sagging and construction performance of the water-based colored paint, and the effectiveness is much higher than that of the traditional viscosity cup or rotor viscosity and the like.
According to the method for determining the rheological parameters of the fluid and the application thereof, the yield stress of the coating in construction application is obtained by testing the viscosity of the coating at different shear rates, the sagging, leveling and workability of the coating on site are predicted, and the better coating appearance is ensured. According to the measured data, the yield stress of different coatings under different construction conditions can be confirmed within a certain range, and the leveling and sagging properties are optimal. The method is a very effective detection and quality assurance means in aspects of formula design, production control and the like.
The terms "first" and "second" as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, unless otherwise specified. Similarly, the appearances of the phrases "a" or "an" in various places herein are not necessarily all referring to the same quantity, but rather to the same quantity, and are intended to cover all technical features not previously described. Similarly, modifiers similar to "about", "approximately" or "approximately" that occur before a numerical term herein typically include the same number, and their specific meaning should be read in conjunction with the context. Similarly, unless a specific number is used to modify a noun, it is intended that the specification be read as including both the singular and the plural, as well as the singular and plural of the present technical features.
The embodiments described in the specification are only preferred embodiments of the present invention, and the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the present invention. Those skilled in the art can obtain technical solutions through logical analysis, reasoning or limited experiments according to the concepts of the present invention, and all such technical solutions are within the scope of the present invention.

Claims (9)

1. A method for determining a rheological parameter of a fluid, comprising the following steps in sequence:
(1) preparing a paint sample, diluting the paint to construction conditions, simulating the shear rate of the paint sample during spraying, and testing the viscosity;
(2) viscosity was measured and the shear rate of the simulated paint samples was less than 0.2 to 0.3s-1；
(3) Viscosity was measured and the shear rate of the simulated paint samples was less than 0.4 to 0.6s-1；
(4) Testing viscosityDegree, shear rate of simulated paint sample of less than 0.7 to 0.9s-1；
(5) Viscosity was measured and the shear rate of the simulated paint samples was 1.0 to 1.2s-1；
(6) Viscosity was measured and the shear rate of the simulated paint samples was 1.4 to 1.6s-1；
(7) Viscosity was measured and the shear rate of the simulated paint samples was 1.8 to 2.2s-1；
(8) Viscosity was measured and the shear rate of the simulated paint samples was 2.8 to 3.2s-1；
(9) Viscosity was measured and the shear rate of the simulated paint samples was 4.0 to 5.0s-1；
(10) An appropriate model is fitted to a measured viscosity based on iterative fitting of the model to obtain the yield stress of the paint sample.
2. The method of claim 1, wherein the shear rate in step (1) is from 500 to 1000s-1。
3. The method of claim 1, wherein the model used is the Hershel-Bulkey model.
4. The method of claim 3, wherein the power function of the model is
Figure FDA0002790035920000011
Wherein k is the viscosity coefficient (Pa S)n) N is the flow index, η is the viscosity (Pa s),
Figure FDA0002790035920000012
is the shear rate(s)-1)，τ0Yield stress (Pa).
5. The method of claim 4, wherein in the model, the shear rate of steps (2) to (8) is on the X-axis and the viscosity is on the Y-axis.
6. The method of claim 1, wherein the viscosity is measured at a temperature of 23 ± 0.5 ℃.
7. The method of claim 1, wherein the criteria for qualifying the fluid is a solvent borne clear coat yield stress of 0.95 ± 0.05Pa and a water borne color coat yield stress of 0.55 ± 0.05 Pa.
8. The method of claim 1 wherein the application conditions are 23 ℃ application viscosity paint-4 cups for 25 to 40 seconds for solvent-based varnishes.
9. The method according to claim 1, characterized in that for aqueous paints the application conditions are a viscometer of type B at 6rpm with a viscosity of 1000 to 7000mPa s.
CN202011311747.0A 2020-11-20 2020-11-20 Method for determining a rheological parameter of a fluid Pending CN114518302A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116660099A (en) * 2023-07-24 2023-08-29 绵阳新启科技有限公司 Water-based paint fluidity detection system and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116660099A (en) * 2023-07-24 2023-08-29 绵阳新启科技有限公司 Water-based paint fluidity detection system and method
CN116660099B (en) * 2023-07-24 2023-10-31 绵阳新启科技有限公司 Water-based paint fluidity detection system and method

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