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.
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.
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