Application and technical standards for three-dimensional printing materials

In order to ensure the three-dimensional effect of three-dimensional printing, considering the material of the grating, it is also necessary to select the grating with different parameters in combination with the image effect.

1. The material of the grating

The material of the lenticular sheet should have high transparency, high refractive index, good gloss, strong plasticity, stability, etc. The materials used for making toys and food packaging also require non-toxic and harmless. At present, three kinds of gratings, namely, Polystyrene (PET), Polypropylene (PP) and Polyvinyl Chloride (PVC), are used in the market.

1 Polystyrene resin (PET)

Polystyrene (PET) is used to make rigid plastic gratings, which can be printed directly with ordinary inks. Polystyrene raw material is processed into an lenticular lens grating by injection molding.

Polystyrene is colorless and transparent (transparency 88%-92%), refractive index 1.59-1.6, non-ductile, flammable. Because of this high refractive index it gives it a good sheen. Its tensile strength is 3.52-6.33 MPa, its bending strength is 6.12-9.84 MPa, and its thermal deformation temperature is 70-98°C.

The chemical properties of polystyrene are resistant to certain mineral oils, organic acids, bases, salts, lower alcohols and aqueous solutions. Encountered by hydrocarbons, ketones, higher fatty esters, etc., eroded and softened, soluble in aromatic hydrocarbons and toluene, ethylbenzene, and styrene monomers. In some cases, the degree of erosion of polystyrene by chemical agents can be reduced by annealing, stress relieving, and other measures.

Polystyrene has good stability, high picture quality, non-toxic raw materials, high chemical resistance, but it is difficult to bond processing. Mostly used for toys, fine advertising, etc.

2 Polypropylene (PP)

Polypropylene (PP) can be directly printed with ordinary ink, but the surface to do the spark treatment, the ink drying faster than polystyrene.

Polypropylene is softer than polystyrene and harder than PVC. High stability, but the image quality is normal. The raw materials are non-toxic, low in chemical resistance, easier to be bonded, and used in packaging and stationery.

3 Polyvinyl chloride (PVC)

Polyvinyl chloride (PVC) for the production of soft plastic cylindrical lens gratings. A hot oil press is used to press the picture and the polyvinyl chloride film base through a metal grating roller or grating plate.

Polyvinyl chloride is a polymer compound formed by the polymerization of chlorinated olefins and is difficult to burn. Although polyvinyl chloride and polyethylene are both milky white, polyvinyl chloride can be used as a colorless, transparent and glossy film, and can produce various softness films based on the plasticizer content. This material has high fastness after the pulse heat sealing and high frequency heat sealing. The chemical properties of polyvinyl chloride have good chemical resistance, but poor thermal stability and lightfastness. Hydrogen chloride starts to decompose at 140°C, and stabilizers are required to make it. PVC content of 56% -58%, low molecular weight of soluble ketones, esters and chlorinated hydrocarbon solvents; high molecular weight is difficult to dissolve.

PVC has low stability and rough picture quality. In addition, because PVC gratings are toxic and not environmentally friendly, they are not generally used in toys and food packaging products in Europe and the United States.

2. According to the final effect of the screen to choose the grating material

According to the principle of stereoscopic vision, if we can allow our left and right eyes to see two images taken at different positions, the brain can synthesize the two images and feel a three-dimensional space. Using the imaging effect of the grating plate to observe different images from different angles, we can see different images. So if we place the grating perpendicular to the two eyes, because the two eyes have different viewing angles to the grating, the two eyes will see two different The image produces a three-dimensional effect. In order to obtain a better three-dimensional effect, it is usually not to use only two images, but to use a sequence of stereoscopic images. In this case, depending on the position of observation, you can see two pairs of the sequence at the same time. Image, you can feel the three-dimensional effect.

The three-dimensional raster requires delicate images and sharp changes, so it requires a smaller range of viewing angles, so that the visual effects are real and the three-dimensional effect is strong.

The anamorphic grating places the grating between two eyes. Note that the two lines keep the angle of the line of the grating parallel, so the two eyes see the same image. If the image is composed of a series of continuous animations, then When moving or flipping the grating up and down, the angles of the eyes and the grating will change, and we will also see successive images one after the other, that is to see a change effect.

Alternating gratings require a larger range of viewing angles, so that the range of image transformation is large, and there is little crossover between different images, and the image transformation can be clearly perceived. According to the analysis, it can be seen that this type of grating requires a smaller ratio of its thickness to the grating pitch, so that a larger viewing angle range can be obtained.

If a three-dimensional grating is used to produce the effect of change, it usually leads to incomplete image erasing; however, using three-dimensional grating to produce a three-dimensional effect will make the three-dimensional effect not strong. So choose the right grating plate based on the required performance.

3 grating grating accurate measurement method

The grating pitch is generally precisely matched by using a series of grating test strips with a nominal pitch. There are many types of grating pitch test strips, and different software vendors use different test strips, but the basic principles are basically similar. It is to use a grating plate's imaging characteristics to load a variety of grating pitch parameters to create a series of black and white patterns so that when the grating plate and the nominal grating pitch are in agreement, observation at a certain angle will show specific pattern.

Consisting of a series of black and white stripes, the test is performed on the grating test strip with a grating press. When one of the stripes is observed at a certain angle, it shows a completely white pattern. When viewed from a different angle, In the case of a completely black pattern, the grid pitch value under the test strip is the actual grid pitch of the grating plate.

Before the 1990s, paper products, packaging, printing adhesives, varnish, and film adhesives were mostly formulated using solvent-based high-molecular polymers as base materials. Due to the large amount of organic solvent used in the base material as a dilution, with the application of the product, the organic solvent will eventually volatilize and disperse polluted air, wasting resources, coupled with the organic solvent is mostly flammable and explosive materials, and there are serious fire hazards. After the 1990s, with the continuous strengthening of foreign environmental laws and regulations, Western industrialized countries have continuously developed waterborne adhesives and waterborne varnish products that use water instead of organic solvents. The products developed by American National Starch Chemical Co., Ltd., Fuller Chemicals, Akzo Nobel, and Germany's Henkel Chemicals, etc., as environmentally-friendly water-based materials, have come out on the market due to their excellent performance and affordable price. Favored by the market. According to literature data, the output of these water-based products has been increasing from 20% to 30% annually since 1991 and ending in 2005. In 2005, a total of 1.5 million tons of products were produced, which accounted for 15% of the annual output of waterborne adhesives and waterborne gloss oils for global packaging printing. The domestic research and development of waterborne adhesives for packaging printing and waterborne varnish started late. In the first 5 years of this century, although a few manufacturers introduced waterborne products to the market, most of them have low technical content and poor application performance, compared with foreign products. There is still a big gap. Some manufacturers' product lines generally use domestic non-specific emulsions and other general water-soluble polymers for blending, or starch modification, and adding a small amount of non-specific latex. With multiple performance defects, it is difficult to adapt to the needs of the printing industry. In recent years, some water-based emulsions have been prepared by synthetic means, but the process is old, the technology is not at a high starting point, and the products lack market competitiveness. Therefore, in the high-end products, foreign products still account for 70% of the market share in the country.

Since the beginning of this century, the application of water-based adhesives for packaging and printing and waterborne varnish is in the ascendant stage of development. This is because water-based products not only meet the international trend of development, but also comply with China's current sustainable development policy. In 2005, the total output value of the domestic packaging and printing industry was about 300 billion yuan, while the consumption of plastic (including adhesives, varnish, and plastic film) was approximately 4.5 million tons, including the East China Market (Jiangsu, Shanghai, and Zhejiang Provinces) and the South China Market (mainly In the Pearl River Delta Region, each accounted for about two-fifths of the market share, while the rest of the country accounted for about one-fifth of the market share. The market demand for water-based adhesives and water-based varnish and water-based adhesives (including aluminized transfer adhesives) is approximately 2.5:0.5:1. That is, the market demand for water-based adhesives is about 2.8 million tons, water-based gloss oil is about 560,000 tons, and water-based adhesive glue is about 1.1 million tons.

development trend

Market demand continues to grow rapidly

The demand for most adhesives and ancillary products in China is expected to increase at a rate of more than 10%. By 2010, the total output will reach 7.3 million tons. The average annual growth rate of production is 11.5%, with a total value of 57 billion yuan. The average annual growth rate It is 11.8%.

Environmental protection and energy-saving adhesives and their accessory products accelerate development

As China has actively promoted the fundamental transformation of economic growth mode, it has taken improving the efficiency of resource utilization as the core, accelerated the adjustment of product structure and strengthened the awareness of conservation. Under the guidance of this guideline, environmental protection and energy-saving adhesive products have attracted much attention and will be developed faster. It is expected that during the “Eleventh Five-Year Plan” period, it will increase at a rate of 12% to 20% per year. Among them, the first of five series of (meth)acrylate emulsion adhesives ranked.

High-performance, high-quality and high-tech products have greater development

With the development of China's economy and the acceleration of global economic and technological integration, the demand and choice of products in the market will become more and more demanding. High-performance, multi-functional and environmentally friendly energy-saving adhesive products will be favored by the market. It is expected that these high-tech products will develop at a speed higher than 20%.

The supply of major raw materials will be greatly improved, and foreign-funded enterprises will continue to develop.

During the “Eleventh Five-Year Plan” period, the number of foreign-funded enterprises in China increased, the scale of production continued to expand, capital investment continued to increase, and high-tech products increased significantly. Many famous companies around the world have set up research centers in mainland China to strengthen the research and development of high-tech products and further improve their product quality. Companies such as Bayer, BASF, 3M, Rohm & Haas, Henkel, and Nationalstarch. It is expected that during the “Eleventh Five-Year Plan” period, foreign-funded enterprises will develop in the country with large-scale production and high-tech products. Its product sales will be increased from 40% to 45% to 50% of the total adhesive sales in mainland China.

Product production pattern accelerates to scale, intensive advantages of enterprise concentration

At present, there are many domestic adhesive manufacturers and they are small in scale. According to the statistics of 2003, there are more than 3,500 companies in the country, but there are less than 100 companies on the scale of the scale, of which 15% to 20% of companies fail each year for various reasons. Most enterprises are lagging behind in production technology, low in product quality, poor in technological innovation and scientific research and development, and aging products. They are of a single species and cannot keep up with the rapid development of the market. The reorganization of the industry and the “big reshuffling” status have become apparent, and the product production pattern has been accelerating to focus on large-scale and intensive advantaged enterprises.

Technical development trends of domestic and foreign industry products

Domestic and foreign packaging and printing adhesives, as a new type of printing accessories, have undergone new changes due to the need for environmental protection and energy conservation and consumption reduction.

Development of oily materials to waterborne materials

Such as water-based film adhesive instead of oily film adhesive, water-based varnishes instead of oily varnishes, water-based adhesives instead of solvent-based adhesives.

Single function type to multifunctional type modification

Such as: polar/polar single sticky type; paper/paper adhesive bonding to polar/non-polar bipolar adhesive modified type; paper/membrane bonding; anti-mildew, anti-cut type functional adhesive Replace ordinary glue. The use of nano-materials modified or through special synthesis techniques to make ordinary adhesive to wear, anti-adhesion, high temperature, salt fog resistance, high viscosity, flexibility and other versatility.

Manufacturing Technology Updates

Based on the design of the molecular level, a breakthrough was made in the synthesis method. In this aspect, the linear polymer structure produced by the general classical polymerization process is modified to a self-crosslinked internal crosslinking type, a diplomatic linkage type, and an internal and external multiple crosslinks by a special synthesis method; The transformation of the linear winding structure to the core-shell structure and IPN interpenetrating network structure, these technological breakthroughs are built on the level of molecular structure, and the macroscopic physical and mechanical properties of the material have been broken through the change of the microstructure.

The improvement of water-based soap polymerization to soap-free polymerization (self-emulsification) makes the water resistance, less foam, and MFT value of the product decrease, and the rheological mechanical properties of the colloid are greatly improved.

Breakthroughs in production processes and installations have shifted from labor-intensive and extensive production processes to technology-intensive and intensive production processes.

Development of internal chemical composition of products

To adapt to the needs of different substrates and different bonding methods, the main chemical composition of the main waterborne adhesive used for packaging and printing is composed of plant adhesive, animal glue, polyvinyl alcohol adhesive, polyvinyl acetate adhesive and vinegar-acrylic adhesive. , EVA glue to polyacrylate glue to polyurethane glue, polyurethane modified acrylic glue direction. Among them, depending on the purpose of use, in combination with the need of economic cost, there is a cold blending modification in which the glue is blended with another glue or a plurality of glues. A more advanced approach is to blend a variety of major chemical components that are needed in the former and to manufacture them by copolymerization, such as polyurethane-modified polyacrylate adhesives. This can be expected to obtain better integrated application performance.

Development of Bonding Theory in Application

Bonding theory includes physical adsorption bonding theory, chemical bond bonding theory, weak boundary layer bonding theory, diffusion bonding theory, electrostatic gravitation bonding theory, and mechanical force bonding theory, etc. In addition to the mechanical force bonding theory, there will be some technological breakthroughs in the two aspects of the synthetic production and application of adhesives. For example, some functional monomers and functional auxiliaries will be introduced to improve the bonding behavior between the same interface and different interfaces; some new methods will be used in the design of synthetic molecular structures, such as the synthesis of IPN structures and self-crosslinking structures. , Core-shell structure or soap-free emulsion polymerization method; in the change of the rheological mechanical properties of the colloid, improve the colloid on the substrate wetting and leveling performance, the role of functional additives is very important. The basic starting point for technological improvements or technological breakthroughs that occur is closely related to the application of adhesive bonding theory. At the adhesive application level, the chemical properties of the substrate must first be considered, and then adhesives of different properties should be selected under the guidance of bonding theory to suit the chemical properties of different substrates. In recent years, the bonding theory has played an important role in guiding the synthesis of adhesives, explaining the behavior of adhesive wetting, rheology, infiltration, superposition behavior and understanding the nature of interface bonding.