Section 6 Printing of Building Materials - 2

(2) Surface treatment technology for decorative panels 1. Surface treatment of wood products (1) Dehairing Decorative panels and furniture made of wood, although the surface has been fine-planed or polished, the finish has met the requirements, but it always Some wood fibers that are not completely removed from the wood surface remain on the surface. Once these wood fibers absorb moisture or solvents, they will rise due to wet swelling. Due to the presence of wood wool on the surface of the wood, the color will accumulate around it during finishing and affect the uniformity of coloration. At the same time, the inside of the wooden fur is not colored. When the wooden fur is worn away, the fur breaks and reveals its own color. White spots appear on the paint film, commonly known as sesame white. Therefore, before painting, we must go to wood wool, general furniture can be sanded several times, high decorative wood can use the following methods:
1 Wipe the coating surface with a damp clean rag to allow the wood wool to absorb moisture and expand and stand up. After the surface is dry, polish it with fine sandpaper or old sandpaper. If you add a little bit of glue in the water, the effect will be better;
2 Brush the surface with thin shellac varnish (shellac: alcohol=1:7-8). In this way, the fur can not only be erected but also brittle, so it is easy to sand off;
(3) Using the fire burning method, brush a thin film of alcohol on the surface of the white billet immediately with a fire. After the fire wood wool becomes hard and brittle, easy to sand out. However, this method is only applicable to planes, and it should be characterized by safety when working.
(2) Decontamination of stains on the surface of dirt (such as glue marks, oil marks, etc.) will affect the uniformity of the paint color, as well as the drying of the paint and the adhesion of the paint film. Therefore, clean it before painting. The soiled surface can be sanded with No. 1 or No. 1 half-timbered sandpaper. When you can't rub it off, use a polished short planer to plan the surface clean. Scratches off any glue that remains in the joints and other joints. The traces of oil can be sanded first, then washed with gasoline, or treated with the fire method described above.
(3) When resin is applied to the resin needle material in a local place, the adhesion of the paint film and the uniformity of the color are also affected. Can be used knife, chisel to dig it, and make up the same type of wood, wood fiber direction should be consistent. If digging is not allowed, it can be washed off with organic solvents. Commonly used solvents include turpentine oil, gasoline, toluene and acetone. Last year, after the surface of the resin was dry, 1-2 lanes of shellac varnish were brushed to prevent the internal resin from seeping out again. It can also be washed first with alkali and then with water. Generally, it can be washed with 5%-6% sodium carbonate solution or 4%-5% caustic soda solution to saponify the resin, and then scrub with a brush or sponge and hot water.
(4) Bleaching If the decorative board or furniture is painted in a light color or painted in any color that is not related to the original material color, the surface of the furniture blank is bleached. In general, bleaching is often performed on a partially darkened surface to achieve uniform color on the finished wood surface.
Before bleaching, remove the surface dust. There are many methods for bleaching. The bleaching effect of the same kind of bleaching agent on different materials is different, and the effect of different bleaching agents is not the same.
The commonly used bleaching agents are a mixture of hydrogen peroxide (30% concentration) and ammonia (25% concentration) (hydrogen peroxide:water:ammonia =1:1:0.2); sodium hydroxide solution (a solution of 250 g of sodium hydroxide dissolved in 500 g of water) And hydrogen peroxide.
When bleaching with a mixture of hydrogen peroxide and ammonia, if the veneer is bleached, the veneer can be completely soaked in the mixture. If bleaching is done on the entire panel, the solution can be applied to the surface of the wood and the surface can be wiped clean with a clean, damp cloth when the surface reaches the bleaching requirements. In the case of partial bleaching, to improve the bleaching effect, a small group of clean cotton yarns can be used to impregnate the surface to be bleached with the bleaching solution, and the bleaching agent is always kept on the cotton yarn until the bleaching requirements are met.
Another method of bleaching is to apply sodium hydroxide solution to the surface of the wood and apply hydrogen peroxide after about half an hour. After the treatment, the surface of the wood is scrubbed with water and neutralized with a solution of weak acid (eg, about 1.2% acetic acid or oxalic acid) and then scrubbed with water.
The above two methods for bleaching wood have better effects on ash, eucalyptus and the like, and bleached surfaces do not change color for many years.
Prepare A and B bleach in the following proportions:
A liquid: 10 g of anhydrous calcium carbonate, 60 g of warm water at 50° C.; 80 mL of B liquid: hydrogen peroxide (hydrogen peroxide) solution (35%), and 20 mL of water was added. First, apply A liquid evenly on the surface of the wood. After fully immersing it for about 5 minutes, remove the exudate mixed with the wood surface with wood flour and cloth, and then apply the B liquid directly, and dry it over 3 hours.
Sometimes it takes 18-24 hours to dry. When the desired whiteness is achieved, wipe it repeatedly with a damp cloth and wash until it is not yellow. When not bleaching excessively, reduce the concentration of bleach or shorten the drying time. Bleaching should pay attention to: Do ​​not mix A, B two liquids, the need to use a brush made of plants or synthetic resins, with glass or ceramic containers hold A, B bleach.
For uniform color, high-grade furniture surface bleaching, use 30g bleaching powder, dissolve in 1000g (70°C) aqueous solution, stir evenly on the surface to be bleached, and then brush repeatedly with 60-70°C 0.5% acetic acid solution On bleached surfaces, until the wood is completely whitened, wash it off with soapy water.
(5) Dyeing The color of the transparently finished furniture surface is determined by the color of the wood itself and the color of the paint film.
The dyeing at this time refers to the method of changing the wood color by interacting with the tannins in the wood with certain substances such as ferric sulfate, potassium dichromate, and potassium permanganate before the painting. There are many methods of dyeing, and now China is the most used is the use of ferrous sulfate on the red oak wood thin skin. After this treatment, the thin skin of the beech wood is dark green or light gray, and the adhesive is applied to the appropriate part of the furniture. After transparent finishing, the wood grain is more prominent due to the darkness and streaking of the wood, and beautifies the furniture. surface. After testing, the concentration of ferrous sulfate is about 2%, thin skin needs to be soaked at room temperature for about 8 hours. Heat soaking takes only about half an hour, but the different eucalyptus contains different tannins, and the actual soaking time is also different. When soaking, observe the change of material color regularly to avoid too deep dyeing.
(6) Filling of the finishing surface and embedding of furniture or decorative wood boards White blanks often have holes, such as wormholes, nailholes, cracks formed by dry cracking of wood, countergroove grooves formed in the counter-cutting process, and beside tree branches. Local pits, as well as broad-leaved duct slots. These holes will absorb the general varnish, paint and other coatings, resulting in paint waste and uneven surface finish, affecting the quality of finishing. Therefore, according to the specific conditions, fillers such as putty, water old powder, and oil old powder must be used to fill these holes.
The putty is made up of a large mother's body pigment (commonly used old powder, gypsum, etc.) varnish or color paint, coloring pigment, and an appropriate amount of water and solvent. Putty is generally deployed by painters themselves at the construction site at any time. The putty is not only used for infilling of larger holes, but also for full filling of the finishing surface.
The color of the putty is formulated as needed. The color of the putty should be lighter than the color of the old powder after infilling, but the difference should not be too obvious. If you make a good base color and then make up, then based on the background color, it is very close to the two. The opaque paint does not have strict requirements for the color of the putty, but it also adds coloring pigments.
· The commonly used varnish for putty is shellac varnish, phenol vinegar varnish, varnish, and nitrocellulose varnish. There is also pig blood as the main adhesive material.
The deployment of putty requires a flat board, the tool used is horn scraper or metal scraper.
To adjust the putty, first put the constitutional pigment in the middle of the board, add the paint and then mix it into a high circle around the middle and then lower it in the middle. Put the varnish and solvent in the middle pit, and gradually absorb the constitution pigment with a scraper. Varnish. Putty must be mixed during the preparation of the various ingredients to fully stir and mix thoroughly. The following describes the preparation of several putty methods:
1 The preparation of shellac putty: The shellac putty is formulated into a paste with shellac varnish, old powder, coloring pigment, and the like. The ratio of shellac to alcohol is 1:6 (concentration is 14% of shellac varnish). If the proportion of early glue is large, the hardness of putty inlay after drying is relatively large, and it is not easy to be polished, but it is not easy to fall off. Conversely, if the shellac concentration is low, the putty will have a low hardness after drying, and it will be easy to wear flat and easy to fall off. As early as the formulation of the putty (in percentage by weight), 75% of the old powder, 24.2% of the shellac varnish, 0.8% of the color, the color should be blended according to the requirements of the color depth, and the color of the putty should be lighter than the model color.
In the process of using the shellac putty, the alcohol will gradually thicken due to the constant force of the army. Add some wine and clear it, and then mix and reuse it.
The shellac putty dries quickly, does not sink in the recesses, but has low strength and is generally used for preliminary embedding of macropores.
2 The preparation of the oily putty: The oily putty is usually made of varnish (cooked tung oil) or novolac, plaster, pigment and water. Generally, after the varnish is added into the paste in the gypsum and the pigment, a small amount of water is added to further mix it. If water is added first, the gypsum will suddenly absorb a lot of water and swell and harden, and the particles will no longer be adjusted evenly. During the preparation of the oily skin, it is also necessary to pay attention to the fact that the putty after water absorption continues to swell and harden, and some varnish should be added in time to further mix it thoroughly. Otherwise, the putty will overswell and form a hard block or granule that cannot be used. The formula for the putty can be found in Table 4-18.
Table 4-18 Putty Formula

3.12

The putty has partial embedment and full fill.
When used for partial inlays, putty can be made harder, that is, thick and dry. When used for full filling (called putty), it should be adjusted softer, ie, thinner. The amount of water added in the putty can not be too much, because the water is too much, the oil is easy to precipitate, putty will be white after drying, resulting in putty spots, affecting the appearance of the product.
The putty has good adhesion. Gypsum expands when it is dry, so it can fully plug the hole. However, the drying rate of the putty is slow. If the amount of coating is small, the next process can usually be performed after 2-4 hours.
3 Lak Putty's deployment: The Lak Putty is tuned with a thin powder (nitro-varnish) old powder and a coloring pigment. The used rare-earth gram was made by mixing 1 part of gram plus 3 parts of banana water. Lak putty is the same as the putty putty. Used on the coated surface where further embedding is required, such as partial filling of holes after laquer has been applied in the transparent finish; in the opaque coating, infilling along the eyes after spraying the first film of lacquer. Gap. Lak putty and shellac putty dry faster, so only for partial inlay. Lak putty sand should be sanded after drying.
2. Surface treatment of bamboo products Before the production of bamboo products, pest control, anti-bonding and anti-cracking treatments are required. These methods include:
(1) Impregnation method 1 Solution composition: 2000 g of sodium fluoride; 1000 g of salt, 100 g of phenol, 200 g of ammonia water, and 100 kg of clear water;
2 The bamboo was immersed in the above solution for 5-7 days. After removal, the bamboo was split and immersed in the solution for 2-3 days. Bamboo must be completely immersed in the solution, and the liquid level should be 10cm higher than bamboo.
(2) Pressurization method Use an autoclave (applicable to small bamboo products), pressurize to 2-3kg/cm2, temperature 80-90°C, time 4-6h, remove after drying. If you need to remove the insects, add the medicine to the kettle.
(3) Surface skin treatment method 1 scraping method: remove by hand scraping with a cutter;
2 Fire Department