Coating technology: Coating Pigment Detection

Core tips: 1 Color 1, definition and content Color is a psychophysical quantity, which is not only related to human visual characteristics, but also to the observed objective radiation Color is an important index to evaluate the quality of pigment products The expression of color can be generally divided into two categories, one is represented by three basic attributes of color, such as Munsell color system which classifies and demarcates the surface colors of various objects In this system, H represents hue, V represents lightness, and C represents chromaticity, which is written as HV / C; the other is a set of color representation, measurement and calculation methods based on two sets of basic visual data, namely CIE standard chroma Application scope and advantages of roller ceramic coating Recommended introduction: the surface of ceramic rubber plate used for roller ceramic coating is cast into durable rubber plate by hundreds of independent small ceramic pieces Each ceramic piece has raised characteristics Under general conveyor belt pressure, thousands of unique cast bumps can produce positive traction, prevent slipping and extend the service life of conveyor belt roller At the same time, the bottom layer adopts high-quality rubber, which has strong elasticity and can play a good impact resistance role The scope of application of roller ceramic coating is one three six 83857180 (the same as V) 1 Roller coating in extremely harsh working environment 2 The belt joint is not suitable for fixing with iron buckle; 3 It is suitable for leather Color 1, definition and content color is a psychophysical quantity, which is related to both human visual characteristics and observed objective radiation Color is an important index to evaluate the quality of pigment products The expression of color can be generally divided into two categories, one is represented by three basic attributes of color, such as Munsell color system which classifies and demarcates the surface colors of various objects In this system, H represents hue, V represents lightness, and C represents chromaticity, which is written as HV / C; the other is a set of color representation, measurement and calculation methods based on two sets of basic visual data, namely CIE standard Chroma system The inspection of pigment color can be divided into two categories: one is color comparison method, that is, comparing with the reference sample by visual inspection or instrument test to give the results; the other is direct color measurement method, that is, using instrument or visual inspection to directly give the color measurement value or sample number 2、 Test method 1 Color comparison method ① is equivalent to iso787 / 1:1982 ② The method of color visual comparison in ASTM standard also includes ASTM D 1729-89 visual evaluation of color difference of opaque materials When evaluating color by this method, the order of hue, brightness and saturation is given respectively, and then the general comment is added ① ASTM D 2244-93 is also such a method, but the sample and reference sample preparation method are not provided in the method, and other methods can be referred to for post pulping test 2 There are two methods of color test (direct color test) (1) visual test and instrument test (1) China has not formulated the national standard The foreign standard has ASTM D 1535-95a, and Munsell color label is used to represent pigment color The preparation method of sample size is not provided in the method Refer to other ASTM standards for post pulping test (2) The instrument test method uses the instrument to directly measure the value of pigment color In accordance with this method, there are colorimeter, colorimeter, colorimeter and so on For the determination of pigment color (dry powder and color paste), please refer to section 4-2 whiteness for cake making and film making methods 2 whiteness 1 Definition and content whiteness refer to the degree of whiteness on the surface of an object It is generally expressed by whiteness index W The greater the value, the greater the degree of white The determination of pigment whiteness is for white pigment It is generally divided into dry powder whiteness test and oil film test 2、 Determination method 1 The whiteness of pigment is generally measured by whiteness meter and chromatic aberration meter There are many models The main domestic manufacturers are: Beijing kangguang Instrument Co., Ltd., Hangzhou Qingtong Instrument Development Co., Ltd., Wenzhou Instrument Co., Ltd 2 preparation of the sample before the test (1) before the determination of the whiteness of the dry powder, the right amount of powder is taken, and the powder is made into a powder sampler, and the surface is smooth, without bumps and scratches (2) Before the determination of oil film whiteness, the pigment is made into pigment slurry in a proper way, a small amount of slurry is taken into the oil film sampler, and optical glass flakes are added to make the slurry and glass flakes closely contact One of the important optical properties of white pigment Under certain experimental conditions, the ability of white pigment to lighten the color of colored pigment 2、 Determination method 1 Visual comparison method ① is equivalent to ISO 787 / 17:1973 ② Similar methods include Japanese Industrial Standard JIS K 5101, American DuPont standard and German DIN method ③ Standard blue pulp is provided by Tianjin Dongfeng Chemical Plant 2 Instrument measurement method ① is equivalent to ISO 787 / 24:1985 In addition, DIN 53197 and ASTM D 2745-93 are also such methods 3 The carbon black used in the method of Reynolds index ① is prepared according to the following methods: take 30g carbon black and 250g barium sulfate, put them into the ceramic bowl containing 500g-600g ceramic ball, after premixing, assemble the ceramic bowl on the vibration crusher, run for 20min, mix it fully with the adjusting knife, continue to crush for 20min, and the mixture is screened twice through the 100 mesh filter screen, and then collected for standby The oil used in the method was refined castor oil with a dosage of 0.7 ml ② The blue pigment used in the method is a mixture of 1 part of Ultramarine and 6 parts of barium sulfate; the oil used in the method is refined linseed oil The definition and content coloring power are the ability of pigment to absorb incident light It is one of the important optical properties of colored pigments It usually refers to the ability of coloring pigment to color white pigment under certain test conditions Generally, two kinds of similar pigments are used for comparison 2、 Determination method 1 Visual comparison method ① is equivalent to ISO 787 / 16:1986 Similar methods are ASTM D 387-86 (1994) for color pigments ② There are two kinds of paint bases that can be used: alkyd resin or linseed oil modified by carbamate 2 The instrumental method ① is equivalent to ISO 787 / 24:1985 5 sieve residue I The definition and content are generally defined as the ratio of the mass of the residue after the pigment particles pass through the sieve with a certain aperture to the mass of the sample, expressed in percentage The determination of sieve residue is a general method for the determination of pigment particles 2、 The similar methods are ASTM D 185-84 (1995), JIS k5101 ② Equivalent to ISO 787 / 18-1983 ③ Refer to ISO 787 / 7-1981 ④ Meet the requirements of GB 6003-85 6 Oil absorption 1 Define the quantity of linseed oil needed for the dry pigment to be bound into putty or to form a certain pulp It is used to evaluate the wettability of paint 2、 The determination method ① is equivalent to ISO 787 / 5:1980 Similarly, Article 19 of JIS K 5101-1978 is adopted ② The values in brackets are non SI units for reference 7 PH value 1 Definition and content determination of pH value of pigment suspension in water is a common method for determination of pH value of pigment 2、 Determination method ① is equivalent to ISO 787 / 9:1981 Similar methods include JIS k5101, ASTM D 1208-84 (1989), etc The difference is that the Japanese standard uses 5% concentration and the extraction solution for determination; the ASTM standard uses 10% concentration and the suspension for determination ② ASTM D 1208 uses colorimetry in addition to potentiometry This method uses a suitable indicator to determine the pH value, and a group of pH standards or similar colorimetric methods are used for determination 1 Definition and content: pigment water soluble substance refers to the substance soluble in water in pigment, generally refers to some soluble salts When pigment is used in paint, these water soluble substances have a great influence on the performance of paint It is the catalyst of pigment photosensitivity, which can promote the early destruction of dry paint film, and also can lead to the acceleration of bottom metal corrosion Therefore, it is very important to control the content of water soluble substances in pigment There are important methods and resistance methods for the determination of water-soluble pigments The results of the two methods are expressed in different ways, but their meanings are the same In addition, for specific applications, there are corresponding determination methods for the types and contents of water-soluble substances 2、 Determination method 1 Weight method ① refers to ISO 787 / 8:1979 The difference is that this method uses slow filter paper or glass filter, while the international standard uses colloidal filter ② Refer to ISO 787 / 3:1979 See note ① for differences Similar methods are JIS k5101 and ASTM d1208, both of which are thermal extraction methods 2 Resistance method ① is equivalent to iso787 / 14:1973 ② This standard specifies to use electric bridge or conductivity meter for measurement At present, all units use conductivity meter for measurement ③ Other determination methods include GB / t5211.11-86 determination of sulfate, chloride and nitrate in pigment water (refer to iso787 / 13:1973); GB / t13451.1-92 determination of nitrate in pigment water (equivalent to ISO 787 / 19-1974) 9 Covering power 1 Definition and content the covering power of pigment is also one of the important optical properties of pigment When the pigment is dispersed in the medium to form the film, the opacity of the film is completely produced by the pigment In fact, the evaluation of pigment covering power is to evaluate the ability of the pigment to cover the substrate in the film The covering power of paint (color paint) is generally expressed as the area of base material (i.e coating rate) (m2 / L or m2 / kg) that can be covered by unit volume or quality of paint (color paint) In Chinese standards, the minimum amount of paint required to cover unit area is expressed The corresponding conversion of the color paint into the amount of pigment The hiding power of pigment is defined as the area per unit mass of pigment that can cover the base material, which is generally represented by the minimum amount of pigment (g/m2) needed to cover the base material per unit area When the reflectance method is used, the paint is coated on the black-and-white substrate, and Rb (reflectance on black substrate) and RW (reflectance on white substrate) are measured With the increase of film thickness, Rb / RW (contrast ratio) also changes When the film thickness increases to Rb / RW = 0.98, it is considered to be completely covered Therefore, the pigment covering power can also be defined as the amount of pigment used per unit area when the ratio CR = 0.98 At present, ISO 2814 has been revised and incorporated into ISO 6504 as part 2 In addition to the above standards, the original standards ISO 3905 and iso3906 for the determination of hiding power have also been revised and incorporated into Part 3 of ISO 6504 (issued in 1998) This standard is to measure the contrast ratio of light color paint under the fixed coating rate, so as to measure the covering power In addition, ISO 6504.1-1983 has been equivalent to GB / T 13452.3-92 (K-M method for determination of hiding power) (applicable to white and light colored paints) During the measurement, the coating with different thickness is prepared first, and then R ∞ and Rb are measured by colorimeter, and then the value of covering force can be obtained by looking up the table If the covering power of pigment is taken into account, a certain method can be used for pulping and then the measurement can be carried out 2、 Test method ① similar Method ASTM D 344 uses black and white paper card Use syringe to take the same amount of standard sample and sample paste on the black and white paper card, brush evenly, observe the degree of cover side by side, compare the visual contrast of black and white grid of the sample and standard sample to evaluate the relative covering power of the sample ② Refer to ISO 2814:1973 Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,