How to choose sandpaper base paper

The matrix, abrasives, and adhesives are called the three elements of coated abrasives, while the base paper matrix is ​​the most widely used and the most used material. The base paper is mainly used to produce water-resistant sandpaper, dry sandpaper, wood sandpaper, and paper-based abrasive belts. Coated abrasive manufacturing process, the quality of the substrate directly affects the quality of the product, due to differences in manufacturing equipment manufacturing process, so choose the right base paper to stabilize the product quality has a greater help.

I. Status Quo of Base Paper Manufacturing Enterprises

Because sandpaper is a kind of special industrial paper, the market is narrow and small, and the dosage is not large. The domestic market is less than 20,000 tons per year. With the acceleration of industrialization in China, there has been a large increase in recent years, but due to the special requirements of sandpaper, the market profit The space is small. The state has almost no support for the R&D and technical support of the base paper. In the original planned economy, several state-owned base paper manufacturers were completely dismantled, shut down, or converted, so the base paper manufacturing companies were few, and at present, only Hubei is the production capacity of papermaking equipment. Haifeng Paper Jiangxi Lemen Paper and several other enterprises support the development of the industry.

The above-mentioned base paper production enterprises can basically meet the needs of the sandpaper production enterprises to select the base paper, especially the heavy-weight sandpaper-laminated paper, all of which originally relied on imports, and can now be produced in China. Some products can basically replace imports. However, the production of ultra-precision ground paper base paper ultra-heavy paper-based belt base paper, because there is still a certain gap between the process equipment and foreign countries, is still unable to meet the requirements of coated abrasives production enterprises, need to speed up innovation and improve R & D capabilities manufacturing level.

Second, the original paper misunderstanding

1. Coarse and fine-grained sandpaper uses the same base paper. A coarse and fine-grained sandpaper has a large difference in the amount of sand and sand, and the amount of base glue and compounding amount are different. The requirements for the base material are also not the same. In general, coarse weight should be selected for the base paper, and the fine base for quantitative light base paper should be selected. On the smoothness of the two papers, the requirements for coarse and fine grained sandpaper are also different. The breakdown is due to the small sand particles, the small amount of glue, the smoothness of the paper surface is high, and the special surface can not have paper hair, but the coarse eye requires relatively looser.

2, the base paper and the binder do not match. As the raw paper copying process is adapted to the production of different quality sandpaper by the coated abrasive manufacturing enterprise, the process is adjusted accordingly. For example, the selection of raw and auxiliary materials for papermaking, grade B, and latex papermaking is not the same, so sandpaper production companies must choose the right binder to match the original paper. In general terms: Grade A paper is mainly used for the production of silicon carbide transparent sandpaper epoxy resin as a binder; Grade B paper production of ordinary water-resistant sandpaper alkyd resin as a binder; latex paper production of dry grinding supercoated sandpaper Epoxy or phenolic resin is used as a binder. Some companies use an alkyd urea-formaldehyde resin as the binder in order to reduce the production cost. These two kinds of papermaking processes are not suitable due to different usage processes. Use a binder with low bond strength as a sandpaper binder, otherwise it will affect the durability of wear resistance. If the production process is not properly controlled, brittleness will also occur, resulting in cracking, peeling of the glue sand and the paper.

3, the pros and cons of the original paper is confused. There are positive and negative sides of the base paper. The original paper is attached to the paper machine net department as a negative side, and the other side is called positive. The front is relatively smooth and flat. Because the raw paper production equipment is not the same and the requirements of coated abrasives production companies are not the same, there is a big difference between the positive and negative sides of the base paper, the oil absorption is not the same, and the smoothness is also very different. Therefore, it is necessary to choose according to the coarse and fine particle size requirements of the production enterprises. Use positive and negative planting sand. A base paper manufacturer has marked the front and back when it leaves the factory, and there is no indication. It can be determined by the following method: When the structure of the paper is observed with the naked eye, the paper can be folded and observed. Another method is to place the strips in an oven and observe the curling method. Curling one side is often called the reverse side.

4, the original paper temperature limit. Because of the difference in the manufacturing process of the base paper, the temperature resistance of the base paper is determined. The normal water-resistant sandpaper can meet the production requirements at 70-80°C. The rosin sizing agent A-grade base paper can be used if the paper is processed or the production exceeds 100°C, or when the drying time is too long. It is easy to produce brittleness, and it is particularly prone to breakage and breakage. However, the use of a sizing agent to produce Class A base paper can reach 120°C without brittleness. Therefore, the production company needs to understand the properties of the base paper, reasonably control the temperature according to different process requirements, and achieve correct use, so as to avoid damage to the substrate due to high temperatures, resulting in sandpaper quality problems.

5, the greater the pull the base paper may not be easy to use. In the papermaking process, if the pulp fiber is not added with chemical aids, its strength is not enough. In order to improve the binding force between the fibers and enhance the paper strength and water resistance, a certain amount of chemical aids are usually added during pulping or papermaking. However, if this additive is used in excess, it will also prevent the resin from infiltrating. Therefore, we often say that it does not absorb oil. There is a misunderstanding that there is a tendency to increase the pull of paper. The only indicator that does not reflect the quality of the original paper must be comprehensively tested for other physics. Indicators such as quantification, tightness, flexion resistance, absorbency, moisture, etc.

Third, sandpaper base paper requirements

1, appearance quality. Generally speaking, the basic paper looks like a color is basically the same, in particular, each batch of natural paper should be the same, otherwise it will affect the trademark surface color. The dust should not be excessive, and no pleats, wrinkles, drapes, or perforations are allowed. In particular, all kinds of colored paper cannot have variegated spots. Three degrees of smoothness, the paper surface is required to be smooth, the hair cloth marks can not be too obvious, both sides should be the same in the quantitative and thickness, otherwise it is easy to run away when producing. The trimming edges of the four major rolls are neat and there must be no breaks. The five paper core tubes are in good condition, and the hardness is better. The weight of each large roll cannot be too large. Generally, it is appropriate to use 300-600 kg per roll according to the specifications.

2, internal quality. First, the sandpaper base paper should be made from 100% kraft softwood pulp. You cannot select “sandwich paper”. When you make paper, add a certain amount of waste paper pulp to the paper, and then use a good pulp noodle to make it look no different from the original pulp production paper. . Second, according to the production of different varieties and select the appropriate quantitative base paper, fine-grained with light paper, coarse-grained heavy-duty heavy paper, the greater the quantitative, the higher the intensity. Three should choose the tightness. The tightness is too large, the structure of the paper is tight, and the strength is large, but the flexibility is poor. On the contrary, the tightness of the small paper structure is loose, and although it is soft, the strength is low. Four should have a certain degree of water resistance. Low water absorption, avoid moisture absorption and deformation, especially after sandbread drying. In particular, the production of water-resistant sandpaper requires better resistance to water. Five raw paper fiber uniformity is better, especially the production of transparent sandpaper, if the original paper formation is not good will lead to uneven oil absorption, but also produce flower spots or a phenomenon of the curtain. Six production super-precision grinding and polishing sandpaper base paper heavy-duty powerful belt base paper, due to the gap between domestic base paper and foreign original paper, at present, this field can only use foreign products, but the production of round sand tray, low-grade paper tape, domestic paper can be used .