GB/T 2679.11-1993 Qualitative analysis of inorganic fillers and inorganic coatings in paper and paperboard - Electron microscope/X-ray energy dispersive spectrometry
Some standard content:
National Standard of the People's Republic of China
Qualitative analysis of inorganic fillers and inorganic coatings in paper and paperboard-Electron microscope/X-ray energy spectrometry
Paper and hoard-Qualitative analysis of miacralFiller and mineral coating-SEM/EDAX method1 Subject content and scope of application
GB/T2679.11-93
This standard specifies the qualitative analysis method of inorganic fillers and inorganic coatings in paper and paperboard using electron microscope and energy spectrometer. This standard is applicable to the variety identification and component analysis of inorganic fillers and coatings in paper and paperboard, and is also applicable to the raw material analysis of inorganic fillers and pigments for papermaking.
2 Reference standards
GB450 Paper and paperboard sample collection
GB 463 Determination of ash content of paper and paperboardwwW.bzxz.Net
GB742 Determination of ash content of pulp
3 Principle
Inorganic fillers and coatings used in papermaking generally include talc, calcium carbonate, kaolin, natural gas dioxide, barium sulfate, etc. The filler or material can be identified by observing its granular morphology and crystal morphology using an electron microscope. When the electron beam is irradiated on the sample, a characteristic X-ray is emitted, and its energy varies with the element. Using a lithium drift delay detector, this signal can be collected and sorted by a computer to achieve the purpose of analyzing the element. 4 Reagents and materials
4.1 Distilled water or deionized water
4.2 Potassium metaphosphate ([NaPO, J): 0.1% solution. 4.35040 or 5070 organic dispersant: 0.1% solution. 4.4 Propylene (CH,COCH,): chemically pure (for cleaning electron microscope and copper mesh). 4.5
Concentrated hydrochloric acid (FICI), chemically pure (for cleaning copper mesh for electron microscope) 4. 6 D76 developer.
4.7D72 developer.
4.8 Acidic extension solution.
High-purity gold wire: purity 99.99%, rm
High-purity carbon rod; purity 9999%, 5mm×100mm. 4.10
Dichloroethylene (CH,CHCI,): chemically pure. Polyvinylformvar (polyvinylformvar) dicyanoethylene solution, 0.2～0.5% (m/m). 4.13$3ram copper mesh for electron microscope.
National Technical Supervision High Commissioner for Industry and Commerce approved on August 7, 1993 298
Implementation on March 1, 1994
4.14 120 or 135 photographic negatives.
4.15 No. 2 or 3 photographic enlargement paper.
5 Receivers and equipment
General laboratory instruments
GB/T 2679.11--93
High temperature furnace; temperature control range, room temperature ~ 1 000 adjustable. 5.3 Oven: temperature control, 1052℃. 5.4 Porcelain snail: 30~~50mL.
5.5 Agate mortar: 50~70mm.
5.6 Transmission electron microscope and its necessary accessories. 5.7 Scanning electron microscope and its necessary accessories. 5.8 Energy spectrometer used in conjunction with scanning electron microscope or transmission electron microscope. 5.9 Peeling needle and tweezer
5.10 Wrinkle sheet: 25mm×75mm×1.5mm. 5.11 Cover glass: 20mm×20mm.
5.12 Optical microscope, 50~1500 times.
5.13 Vacuum coating machine, vacuum degree greater than 1.33×10-Pa (1×10*mmHg). 6 Sampling
Sampling shall be carried out in accordance with the provisions of GB450. Since the number of samples analyzed by electron microscope is very small, special attention should be paid to the representativeness of the samples when sampling. 7 Qualitative analysis of inorganic fillers and coatings by transmission electron microscope 7.1 Preparation of support film grid
Support film grid is a tool used to support the sample, that is, a plastic film that does not show any structure under the electron microscope is covered on a 31mm copper grid specially used for electron microscope. For the analysis of paper fillers and coatings, polyvinyl alcohol formal film (Farmvar) is more convenient to use. When preparing, insert a clean microscope slide into a 0.2%~0.5% Formvar diethylene solution (4.12) to a depth of 1/2-~1/3 of the length of the slide, and immediately lift it up. After dripping off the excess solution, the slide is flat and dried. A very thin layer of plastic film is attached to the slide. Use a dissecting needle to cut the film about 21m away from the edge of the slide, so that it can be easily peeled off in water. Then fill a glass container with a diameter of about 15cm2 with distilled water, and gently put the slide into the water at about 45°. Due to the surface tension of the water, the Formvar film will fall off at the cut place and float on the horizontal plane (Figure 1). When the film floats to the water surface, place a special steel mesh for electron microscopy on the film. About 20 to 30 steel meshes can be placed on a complete film. Place a piece of filter paper with moderate water absorption on the copper mesh, and the area of the filter paper is similar to that of the film. When the filter paper is soaked, immediately use tweezers to lift the filter paper, mesh and film at the same time (Figure 2), so that the mesh is attached with a thin layer of support film. Air-dry at a temperature of 50℃ for use. Cut the film on the glass slide
The film is removed from the water surfaceGlass slide
Figure 1 Preparation of Formvar support film
1-Water surface: 2-Glass slide + 3Formvar; 4-Exciton 5Reagent needle 291
7.2 Sample preparation
GB/T 2679.11-93
Figure 2 Take the mesh and filter paper with film off the water surface1-Membrane + 2-Mesh; 3Paper
7.2.1 Direct dispersion method: Take about 2g of a representative paper sample and boil it in distilled water for 4-5 minutes. Take it out, rub it with your fingers to disperse the fibers, or use a dissociator to slightly dissociate it to help disperse the fibers. At this time, part of the filler or coating is separated from the fibers and suspended in the water. Take a small amount of the floating blanket, drop it on the carrier net with a support film, and dry it at room temperature to 50°C for use. For each sample, 3 to 5 test pieces need to be made, and then check it with an optical microscope, and select test pieces with moderate density and good dispersion for electron microscope observation. 7.2.2 Ash burning method: For paper and paperboard containing a large amount of adhesive, the fibers are not easy to disperse using the method in 7.2.1, and the ash burning method needs to be used for sample preparation. Take about 10g of a representative paper or paperboard sample, carbonize it in a covered porcelain jar according to the GB742 method, and then burn it in a high-temperature furnace at a temperature of 575±25°C to burn the organic matter. Grind the ash liquid with an agate mortar, take a small amount of the sample and place it on a glass slide, drip 2 drops of 0.1% sodium hexametaphosphate (4.2> dispersant, cover with a cover glass, use the finger to move the cover glass, and use the surface tension of the water between the two glass slides to further disperse the ash particles. Wash the dispersed ash residue into a beaker with water, mix it, take a small amount of this suspension with a pipette, drip it on the support film, and air dry it for inspection.
If the filler or detergent in the sample is estimated to be calcium carbonate, it is better to use 507 or 5040 dispersant (4-3). 7.3 Electron microscope inspection and identification
Place the prepared test piece under a transmission electron microscope for inspection. Different fillers have different physical forms, so the inorganic fillers and coatings added to the paper products can be qualitatively identified according to the crystal form and particle size of the sample under the electron microscope. The magnification selected for observation varies with the object: for example, talcum powder can be seen at 1000-2000 times, calcite sulfate and calcium carbonate can be seen at 5000-20000 times, and titanium dioxide can be seen at 10,000-20,000 times.
The crystal forms of different fillers are shown in Figure A1 and Figure A16, which can be used for comparative reference during identification. The crystal characteristics of various inorganic fillers and polyester materials under the electron microscope are briefly described as follows (see the table below). Talc: It is an irregular flat granular body, and the particle size varies with the degree of crushing. Generally speaking, the particles are larger than other fillers, and some layered structures often appear on the edges. Talc is mostly used as a filler, and ultrafine talc is used as a coating. Kaolinite: Kaolin used in the paper industry is mainly kaolinite and halloysite. Kaolinite is a star-hexagonal flake structure. The size, thickness and regularity of the flakes vary with the origin and the quality of the porcelain clay. Thin flakes are translucent under an electron microscope, while thicker flakes are opaque. The grain morphology of halloysite is mostly tubular or curly, and the grain size varies with the origin and processing method. Kaolinite and halloysite are mixed, and many kaolins are also mixed with illite, pyrophyllite, etc. This type of mixed ore often has poor performance. Kaolin is mostly used as a coating. Calcium carbonate: It can be obtained by chemical precipitation, which is called precipitated calcium carbonate. It can also be directly processed from ore, which is called natural calcium carbonate. Precipitated calcium carbonate, also known as light calcium carbonate, is mostly used as a filler. It is used to produce thin embossed paper, dictionary paper and cigarette paper, etc. It is also used as a coating for ordinary coated printing paper. Its crystal form is mostly rhombus or spindle-shaped, some have cavities in the middle, and the cross-section is mostly polygonal. The grain size and regularity vary with the processing process, generally 0.5-1.0 pm. Natural calcium carbonate has no fixed crystal form. The particle size varies with the degree of ore crushing and screening. It is generally about 0.2-1.5 pm, and the particle size of ultrafine calcium carbonate is much smaller than the above value. Titanium dioxide: commonly known as titanium dioxide, made from ores, including sharp silver ore and rutile ore. The crystal form of titanium dioxide of the two ores is not much different. Both belong to the tetragonal crystal system, shaped like pebbles, and the particle size range is generally 0.2-0.5 xm. It has a high refractive index and is mostly used as filler and coating for high opacity and high whiteness paper.
Diatomite: There are naturally ground diatomite and calcined diatomite. The particle size is generally 2-10 μm. The morphology of the crystal grains is characterized by many honeycomb-like holes on the crystals. The complete crystals are disc-shaped. They are rarely used in the papermaking industry and are mainly used for wallpaper coatings.
Diatomite: A hydrated calcium hydroxide complex made of calcium hydroxide, potassium alum, and aluminum hydroxide. The particle size is generally 0.2-2 μm. The crystal shape is mostly needle-shaped. It is characterized by small particle size, low density, high brightness, and high whiteness. It is mostly used in low-quantity coatings.
Diatomite: It is mostly used as a material in the preparation of photographic paper and wallpaper coatings. It has excellent opacity. Its properties are large density, fine particles, and irregular elliptical and rectangular crystal shapes. Barium sulfate: also known as barite or barite powder, the particle size is about 2-5 μm, belongs to the orthorhombic system, and is mostly used for photographic paper coating. Asbestos: There are varieties such as blue asbestos and chrysotile, which are fibrous and mostly used for thermal paper products and special filter paper. According to the crystal morphology observed by electron microscope and the spectrum of Figure AI~Figure A16, the optical mechanical fillers used in paper and paperboard can be identified, but some fillers or coatings have too many cross-states, or are affected by sizing or burning, which makes it difficult to make a clear judgment. At this time, it is best to use an energy spectrometer to perform component analysis at the same time. The composition, crystal form and use of commonly used optical fillers and coatings in papermaking are shown in the table. 31
Filler name
Calcium carbonate
Calcium phosphate
Approximate composition
Characteristics and uses of mineral fillers for papermaking
Main particles
Small fire area
CaCO: Mg, MRCO, presence (some Mg), MgC (variable)
Figure C (OH), tooth
Precipitated calcium carbonate
Calcium hydride (CacCls) precipitation method
Calcium carbonate
* Aged soil
Halloyite
Kaolin
Phosphorus algae
Talc| |tt||Acid-free
Illite
Hydrated calcium sulfoaluminate complex
Natural finely ground diatom
Baked diatom
Ordinary talc
Ultrafine talc
Sharp diamond monoxide
Zinc hydride
Rutile dioxide
White cake
Color pigment
Sodium sulfate
Color, white, green vein
Product silicate
A,Si,O(H)s
A,SiO..(OH).4H.0
(Sig)(Al Mgn.,O2,(OH)
K,Al,Fe.Mg>
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