A starch-based wet-transparent coating and a preparation method thereof

Abstract

The invention discloses a starch-based wet transparent coating and a preparation method thereof, which comprises the following components by weight: 20-40 parts of cassava starch; 20-30 parts of silica gel powder particles; 5-10 parts of calcium carbonate powder; 2-3 parts of glycerol; 10-15 parts of nano zinc oxide; and 120-160 parts of water. The invention is prepared by mixing the above components. The obtained coating can have a flat and smooth coating surface without bubble particles when the coating thickness is 0.5 mm or more, and can achieve complete covering of the graphics at the covered part. At the same time, when a water pen is used to stroke it, it can respond quickly within 1 second to achieve the effect of wet water transparency, and the transparency is extremely high after being wet, and there is no obvious obstruction to the observation of graphics. In terms of wear resistance, it can be scraped back and forth more than 30 times without breaking under a pressure of 5 Pa.

Description

Technical Field

[0001] The invention relates to the field of bio-based new materials, and in particular to a starch-based moisture-transmitting transparent coating and a preparation method thereof. Background Art

[0002] In recent years, the call for environmental protection and sustainable development has become increasingly louder. In many fields such as inks and coatings, the possibility of greening is being explored. The most common method at present is to use water-based materials to replace the original solvent-based materials in the product to reduce VOC emissions. However, at present, water-based resins only solve the problem of non-toxicity, but there is still a large technical gap in their biodegradability and VOC emissions.

[0003] As a natural polymer material, starch has the advantages of being renewable, degradable and cheap. It can be heated and gelatinized to form a colloid with certain film-forming properties. The film formed after drying has certain adhesion and wear resistance, which is very similar to the function of resin. If starch is used to replace water-based resins in inks or coatings, it will be of great significance to the realization of green circulation.

[0004] The base materials of the common functional coatings on the market are mostly water-based resins. The advantage of using water-based resins is that they can reduce the use of organic solvents, but it still cannot achieve a completely green cycle. The best way is to replace them with natural film-forming polymer materials, such as starch. However, starch films are brittle and have poor wear resistance. They will fall off after repeated scraping, and starch films do not have the transparent effect when wet. Summary of the invention

[0005] The object of the present invention is to provide a starch-based moisture-transmitting transparent coating and a preparation method thereof to solve the above problems.

[0006] According to one aspect of the present invention, a starch-based wet-transparent coating is provided, which comprises the following components, by weight: 20 to 40 parts of cassava starch; 20 to 30 parts of silica gel powder particles; 5 to 10 parts of calcium carbonate powder; 2 to 3 parts of glycerol; 10 to 15 parts of nano zinc oxide; and 120 to 160 parts of water.

[0007] In some embodiments, the following components are included, by weight: 20 parts of cassava starch; 20 parts of silica gel powder particles; 5 parts of calcium carbonate powder; 3 parts of glycerol; 15 parts of nano zinc oxide; and 120 parts of water.

[0008] In some embodiments, the following components are included, by weight: 30 parts of cassava starch; 30 parts of silica gel powder particles; 5 parts of calcium carbonate powder; 3 parts of glycerol; 10 parts of nano zinc oxide; and 120 parts of water.

[0009] In some embodiments, the mesh size of the silica gel powder particles is 500 to 1500 meshes.

[0010] In some embodiments, the calcium carbonate powder has a mesh size of 500 to 1500 meshes.

[0011] A method for preparing a starch-based moisture-transmitting transparent coating comprises the following steps:

[0012] (1) mixing at least 10 parts of cassava starch with at least 100 parts of water at a stirring speed of 1200 r / min for 30 min;

[0013] (2) heating the starch solution stirred in step (1) at 85 to 95° C. and stirring at a speed of 800 to 1000 r / min for 2 h or more;

[0014] (3) Blending the silica gel powder particles with the calcium carbonate powder for 30 min, adding the mixed powder after stirring in small amounts to the starch solution after heating and stirring in step (2) in batches, and continuing to stir at room temperature and a speed of 2000 r / min for 3 h, adding the remaining tapioca starch and water during stirring;

[0015] (4) Add nano zinc oxide and stir at a speed of 2000 r / min for 30 min;

[0016] (5) Add propylene glycol and stir at 800 r / min for 1 h.

[0017] Compared with the prior art, the beneficial effects of this application are:

[0018] The coating uses starch as a film-forming substrate, realizes the concept of green environmental protection, can be fully degraded and recycled, and adds a small amount of nano filler to improve its film-forming property and surface strength. The present invention prepares the coating by mixing the above components. When the coating thickness is 0.5 mm or more, the coating surface is flat and smooth without bubble particles, and the covered image and text can be completely covered. At the same time, when it is stroked with a water pen, it can respond quickly within 1 second, achieving the effect of wet transparency, and the transparency is extremely high after being wet, without obvious obstruction to the observation of the image and text. In terms of wear resistance, it can be scraped back and forth more than 30 times under a pressure of 5 Pa without breaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the preparation method of the present invention;

[0020] Figure 2 It is a comparison diagram of the effect of wet water color development of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The present application provides a starch-based moisture-transmitting transparent coating, which comprises the following components in parts by weight:

[0023] 20-40 parts of tapioca starch;

[0024] 20-30 parts of silica gel powder particles;

[0025] 5-10 parts of calcium carbonate powder;

[0026] 2-3 parts of propylene glycol;

[0027] 10-15 parts of nano zinc oxide;

[0028] 120-160 parts of water.

[0029] In some embodiments, the mesh size of the silica gel powder particles is 500 to 1500 mesh.

[0030] In some embodiments, the mesh size of the calcium carbonate powder is 500-1500 mesh.

[0031] refer to Figure 1 , a method for preparing a starch-based moisture-transmitting transparent coating, comprising the following steps:

[0032] (1) mixing at least 10 parts of cassava starch with at least 100 parts of water at a stirring speed of 1200 r / min for 30 min;

[0033] (2) heating the starch solution stirred in step (1) at 85 to 95° C. and stirring at a speed of 800 to 1000 r / min for 2 h or more;

[0034] (3) Blending the silica gel powder particles with the calcium carbonate powder for 30 min, adding the mixed powder after stirring in small amounts to the starch solution after heating and stirring in step (2) in batches, and continuing to stir at room temperature and a speed of 2000 r / min for 3 h, adding the remaining tapioca starch and water during stirring;

[0035] (4) Add nano zinc oxide and stir at a speed of 2000 r / min for 30 min;

[0036] (5) Add propylene glycol and stir at 800 r / min for 1 h.

[0037] In step (3), the remaining cassava starch and water are added during stirring. The remaining cassava starch can improve the covering effect, and the remaining water can prevent the viscosity from increasing sharply. The nano zinc oxide added in step (4) can be used to enhance the strength of the film after formation, improve its wear resistance and other physical strengths.

[0038] Example 1: comprising the following raw materials and steps in parts by weight: 20 parts of cassava starch, 20 parts of silica gel powder particles, 5 parts of calcium carbonate powder, 3 parts of glycerol, and 120 parts of water;

[0039] 10 parts of cassava starch and 100 parts of water were mixed and stirred at a stirring speed of 1200 r / min for 30 min;

[0040] The stirred starch solution is placed in an environment of 85-95°C for heating, and stirred at a speed of 800-1000 r / min for 2 hours or more to complete the gelatinization of the cassava starch to form a starch paste;

[0041] 20 parts of silica gel powder particles and 5 parts of calcium carbonate powder were mixed and stirred for 30 minutes, and the mixed powder after grinding was added to the starch paste in small batches, and then the remaining 10 parts of cassava starch were added to the starch paste, and the mixture was stirred at 2000 r / min at room temperature for 3 hours, and 20 parts of water were added during stirring;

[0042] Add 15 parts of nano zinc oxide and stir at a speed of 2000 r / min for 30 min;

[0043] Add 3 parts of propylene glycol and stir at 800 r / min for 1 hour.

[0044] Example 2: comprising the following raw materials and steps in parts by weight: 30 parts of cassava starch, 30 parts of silica gel powder particles, 5 parts of calcium carbonate powder, 3 parts of glycerol, and 120 parts of water;

[0045] Mix 20 parts of tapioca starch with 100 parts of water at a stirring speed of 1200 r / min for 30 min;

[0046] The stirred starch solution is placed in an environment of 85-95°C for heating, and stirred at a speed of 800-1000 r / min for 2 hours or more to complete the gelatinization of the cassava starch to form a starch paste;

[0047] 30 parts of silica gel powder particles and 5 parts of calcium carbonate powder were mixed and stirred for 30 minutes, and the mixed powder after grinding was added to the starch paste in small batches, and then the remaining 10 parts of cassava starch were added to the starch paste, and the mixture was stirred at 2000 r / min at room temperature for 3 hours, and 20 parts of water were added during stirring;

[0048] Add 10 parts of nano zinc oxide and stir at a speed of 2000 r / min for 30 min;

[0049] Add 3 parts of propylene glycol and stir at 800 r / min for 1 hour.

[0050] Test methods used:

[0051] Use a film applicator to apply the coating with a thickness of 1 mm;

[0052] Adhesion is tested according to ISO standard 100-grid knife with 2mm11 teeth.

[0053] The wear resistance is tested by using a standard ink wear tester to perform 200 friction tests under the pressure of a 50g weight to test the mass change;

[0054] The wet water color development speed is tested by scraping with a water pen and timing with a stopwatch, and the node is taken when the transparency no longer changes;

[0055] The hiding power is observed with the naked eye, and the judging standard is whether it can completely cover the image or text;

[0056] The coating method uses a standard handheld film applicator and a square preparation device for scraping:

[0057] Group Wear resistance Adhesion Can it be completely covered? Wet water color development speed Example 1 0.25g Level 3 cannot 0.4s Example 2 0.20g Level 0 able 0.5s

[0058] The present invention can be applied to tea sets or lunch boxes, where the pattern of the tea sets or lunch boxes is coated. After drying, the tea sets or lunch boxes are in white color. When used, the pattern can be revealed by wetting with water, thereby increasing the viewing value. Similarly, the present invention can be applied to children's books, where key plots or information can be obtained after wetting, thereby increasing the playability. The present invention can also be applied to anti-counterfeiting labels, where part of the label is hidden under the coating, and the full view can be obtained only after wetting with water. The present invention can also be applied to glass curtain walls, where it can block light on sunny days and allow people to enjoy the rain on rainy days, or it can be printed into a pattern shape, which can be revealed after wetting with water, thereby increasing the interest.

[0059] The coating uses starch as the film-forming substrate, realizing the concept of green environmental protection and being able to achieve full degradation and recycling. Figure 2The present invention is prepared by mixing the above components. The obtained coating can have a smooth coating surface without bubbles and particles when the coating thickness is 0.5 mm or above, and can completely cover the graphics at the covered area. At the same time, when it is stroked with a water pen, it can respond quickly within 1 second to achieve the effect of wet transparency, and the transparency is extremely high after being wet, without obvious obstruction to the observation of graphics. In terms of wear resistance, it can be scraped back and forth more than 30 times under a pressure of 5 Pa without breaking.

[0060] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A starch-based wet-transparent coating, characterized in that: By weight, it includes the following components: 20-40 parts of tapioca starch; 20-30 parts of silica gel powder particles; 5-10 parts of calcium carbonate powder; 2-3 parts of propylene glycol; 10-15 parts of nano zinc oxide; 120-160 parts of water.

2. The starch-based wet-transparent coating according to claim 1, characterized in that: The composition includes the following components by weight: 20 parts of cassava starch; 20 parts of silica gel powder particles; 5 parts of calcium carbonate powder; 3 parts of glycerol; Nano zinc oxide 15 parts; 120 parts of water.

3. The starch-based wet-transparent coating according to claim 1, characterized in that: The composition includes the following components by weight: 30 parts of cassava starch; 30 parts of silica gel powder particles; 5 parts of calcium carbonate powder; 3 parts of glycerol; Nano zinc oxide 10 parts; 120 parts of water.

4. The starch-based wet-transparent coating according to claim 1, characterized in that: The mesh size of the silica gel powder particles is 500 to 1500 meshes.

5. The starch-based wet-transparent coating according to claim 1, characterized in that: The mesh size of the calcium carbonate powder is 500 to 1500 meshes.

6. A method for preparing a starch-based wet-transparent coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing at least 10 parts of cassava starch with at least 100 parts of water at a stirring speed of 1200 r / min for 30 min; (2) heating the starch solution stirred in step (1) at 85 to 95° C. and stirring at a speed of 800 to 1000 r / min for 2 h or more; (3) Blending the silica gel powder particles with the calcium carbonate powder for 30 min, adding the mixed powder after stirring in small amounts to the starch solution after heating and stirring in step (2) in batches, and continuing to stir at room temperature and a speed of 2000 r / min for 3 h, adding the remaining tapioca starch and water during stirring; (4) Add nano zinc oxide and stir at a speed of 2000 r / min for 30 min; (5) Add propylene glycol and stir at 800 r / min for 1 h.

Images