A solvent-free environmentally friendly UV fast-curing coating and its preparation method and application

Abstract

The present invention provides a solvent-free environmentally friendly UV fast-curing coating and a preparation method and application thereof, wherein the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating include UV fast-curing resin; the raw materials for preparing the UV fast-curing resin include terminal hydroxyl branched saturated polyester, hydroxyethyl methacrylate, isocyanate, 2-(2-ethoxyethoxy)ethyl acrylate, acryloylmorpholine, catalyst and photoinitiator. The solvent-free environmentally friendly UV fast-curing coating provided by the present invention is used as pencil coating, by introducing UV fast-curing resin and adopting ultraviolet curing process, VOC emission is greatly reduced, and it is environmentally friendly; it is safer during storage and use; the number of coatings is reduced, energy consumption is reduced, production efficiency is improved, and energy conservation and emission reduction are promoted; its cured film-forming molecular weight is large, the dispersion and encapsulation of pigments and fillers are good, and the performances such as wear resistance, weather resistance, and chemical resistance are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of pencil coatings and relates to a solvent-free, environmentally friendly UV fast-curing coating and a preparation method and application thereof, and particularly relates to a solvent-free, environmentally friendly UV fast-curing coating for pencils with special visual and tactile effects and a preparation method and application method thereof. Background Art

[0002] Pencil coating is a very important part of pencil manufacturing. It not only protects the pencil lead, but also makes the pencil more beautiful.

[0003] Currently, pencil coatings available on the market primarily consist of nitrocellulose and water-based paints. Nitrocellulose pencil coatings have a relatively low solids content, which means multiple coats are required during the painting process to achieve the desired coating thickness and effect. Nitrocellulose pencil coatings also offer average weather and chemical resistance. Prolonged exposure to harsh environments such as sunlight, rain, or chemicals can cause the coating to fade, crack, or peel, affecting the pencil's appearance and lifespan. Nitrocellulose pencil coatings contain a high proportion of solvents, resulting in a high level of volatile organic compounds (VOCs). These VOCs are released into the air during the painting and drying processes, polluting the environment. Furthermore, VOCs may have adverse health effects, such as irritation to the eyes, nose, and throat. Nitrocellulose pencil coatings primarily contain flammable substances such as nitrocellulose. Exposure to open flames or high temperatures can result in dangerous combustion or explosion.

[0004] Water-based pencil paint takes a long time to dry, especially in low-temperature, high-humidity environments, which can impact production efficiency. Moisture evaporates slowly, requiring more heat to dry the paint film. This long drying time leaves a lot of water in the pencil, resulting in a softer film, poor abrasion resistance, and cracking. Water-based pencil paint also requires a smaller amount of paint, requiring multiple coats to achieve a full finish, impacting production efficiency. Water-based pencil paint also has specific requirements for the temperature and humidity of the application environment, requiring strict control during application.

[0005] Therefore, in this field, it is desired to develop a pencil coating which is not only environmentally friendly but also has a fast curing speed and a small number of coatings and can solve the problems of nitro pencil coatings and water-based pencil coatings, such as soft paint films, poor abrasion resistance, weather resistance, and chemical resistance. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a solvent-free, environmentally friendly UV fast-curing coating and its preparation method and application, and specifically to provide a solvent-free, environmentally friendly UV fast-curing coating for pencils with special visual and tactile effects and its preparation method and application method.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a solvent-free, environmentally friendly, UV fast-curing coating, wherein the raw materials for preparing the solvent-free, environmentally friendly, UV fast-curing coating include a UV fast-curing resin;

[0009] The raw materials for preparing the UV fast curing resin include the following components in parts by weight:

[0010] 20-30 parts of hydroxyl-terminated branched saturated polyester;

[0011] 15-20 parts of hydroxyethyl methacrylate;

[0012] 30-40 parts of isocyanate;

[0013] 2-(2-ethoxyethoxy)ethyl acrylate 10-20 parts;

[0014] 2-5 parts of acryloylmorpholine;

[0015] 0.1-0.5 parts of organic bismuth catalyst;

[0016] 1-3 parts of photoinitiator.

[0017] The solvent-free, environment-friendly UV fast-curing coating provided by the present invention is used as a pencil coating. By introducing a UV fast-curing resin, the problem of large VOC emissions of nitro pencil coatings is solved, the harm to human health is greatly reduced, storage and construction are safer, and the problems of soft paint films, poor wear resistance, weather resistance, and chemical resistance of nitro pencil coatings and water-based pencil coatings are solved. The problems of many coating times and low production efficiency of nitro pencil coatings and water-based pencil coatings are solved.

[0018] The present invention chemically synthesizes a UV fast-curing resin specifically for pencil paint, and is used to produce pencil paint with special visual and tactile effects. The resin has a fast curing speed, high gloss, good dispersion effect on pigments and fillers, and paint film performance that is significantly superior to water-based and oil-based pencil paints on the market. Compared with water-based and oil-based pencil paints, the paint film has significantly improved weather resistance, chemical resistance, strength, toughness and other properties.

[0019] In the present invention, the “fast curing” in the “UV fast curing coating” and “UV fast curing resin” means that the coating or resin can be cured within 8-12 seconds.

[0020] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of the terminal hydroxyl branched saturated polyester can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc.

[0021] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of hydroxyethyl methacrylate can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.

[0022] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of isocyanate used can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, etc.

[0023] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of 2-(2-ethoxyethoxy)ethyl acrylate can be 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, etc.

[0024] In the present invention, the raw materials for preparing the UV fast curing resin are calculated in parts by weight, and the amount of acryloylmorpholine used can be 2 parts, 3 parts, 4 parts, 5 parts, etc.

[0025] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of the organic bismuth catalyst used can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, etc.

[0026] In the present invention, the raw materials for preparing the UV fast curing resin are calculated by weight, and the amount of the photoinitiator used can be 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, etc.

[0027] Preferably, the isocyanate comprises hexamethylene diisocyanate.

[0028] Preferably, the photoinitiator comprises 1173 photoinitiator.

[0029] Preferably, the UV fast curing resin is prepared by the following method:

[0030] (1) Add the hydroxyl-terminated branched saturated polyester into a reactor, heat it, and evacuate it to remove the moisture;

[0031] (2) Cooling, filling the reactor with inert gas, then adding isocyanate, reacting, and then adding an organic bismuth catalyst to continue the reaction;

[0032] (3) Add hydroxyethyl methacrylate into the reactor, continue the reaction, increase the temperature, and keep the temperature;

[0033] (4) Cooling the mixture, and then adding 2-(2-ethoxyethoxy)ethyl acrylate, acryloylmorpholine, and a photoinitiator, and stirring to obtain the UV fast-curing resin.

[0034] Preferably, the heating in step (1) is heating to 100-110°C, for example, 100°C, 102°C, 104°C, 106°C, 108°C, 110°C, etc.

[0035] Preferably, the vacuuming time in step (1) is 0.5-1.5 hours, for example, 0.5 hours, 1 hour, 1.5 hours, etc.

[0036] Preferably, the cooling in step (2) is to 60-70°C, such as 60°C, 65°C, 70°C, etc.

[0037] Preferably, the inert gas in step (2) includes nitrogen.

[0038] Preferably, the reaction time in step (2) is 15-25 minutes, for example, 15 minutes, 20 minutes, 25 minutes, etc.

[0039] Preferably, the reaction time in step (2) is 0.5-1.5 hours, for example, 0.5 hours, 1 hour, 1.5 hours, etc.

[0040] Preferably, the reaction time in step (3) is 20-40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0041] Preferably, the temperature in step (3) is raised to 80-85°C, such as 80°C, 83°C, 85°C, etc.

[0042] Preferably, the insulation time in step (3) is 0.5-1.5 hours, for example, 0.5 hours, 1 hour, 1.5 hours, etc.

[0043] Preferably, the cooling in step (4) is to 35-45°C, such as 35°C, 40°C, 45°C, etc.

[0044] Preferably, the stirring time in step (4) is 20-40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0045] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating also include auxiliary agents.

[0046] Preferably, the auxiliary agent includes any one or a combination of at least two of a feeling agent, a leveling agent, a defoaming agent, and a dispersant.

[0047] Preferably, the feel agent comprises silicone resin.

[0048] Preferably, the leveling agent comprises polydimethylsiloxane.

[0049] Preferably, the defoaming agent comprises a modified polysiloxane defoaming agent.

[0050] Preferably, the dispersant comprises polyacrylamide.

[0051] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast curing coating include the following components in parts by weight:

[0052] 80-90 parts of UV fast curing resin;

[0053] 0.1-1 part of hand feeling agent;

[0054] 0.2-1 part of leveling agent;

[0055] Defoaming agent 0.2-1 part;

[0056] Dispersant 0.1-0.5 parts.

[0057] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating are calculated by weight, and the amount of UV fast-curing resin used can be 80 parts, 81 parts, 82 parts, 83 parts, 84 parts, 85 parts, 86 parts, 87 parts, 88 parts, 89 parts, 90 parts, etc.

[0058] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating are calculated by weight, and the amount of the hand feeling agent used can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, etc.

[0059] Preferably, the amount of the leveling agent used in the preparation of the solvent-free, environmentally friendly UV fast-curing coating can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., based on the weight parts.

[0060] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating are calculated by weight, and the amount of the defoaming agent used can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc.

[0061] Preferably, the amount of the dispersant used in the preparation of the solvent-free, environmentally friendly UV fast-curing coating can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, etc., based on the weight parts of the raw materials.

[0062] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating further include any one of glass-coated silver powder, pearlescent pigment, and aluminum powder, or a combination of at least two thereof.

[0063] Preferably, the glass-coated silver powder is glass-coated silver flakes.

[0064] Preferably, the weight proportion of the glass-coated silver powder is 3-6 parts, for example, 3 parts, 4 parts, 5 parts, 6 parts, etc.

[0065] Preferably, the pearlescent pigment is a mica flake coated with a metal oxide.

[0066] Preferably, the weight proportion of the pearlescent pigment is 3-6 parts, for example, 3 parts, 4 parts, 5 parts, 6 parts, etc.

[0067] Preferably, the aluminum powder is resin-coated aluminum flakes.

[0068] Preferably, the weight proportion of the aluminum powder is 1-3 parts, such as 1 part, 2 parts, 3 parts, etc.

[0069] Preferably, the raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating further include 1-3 parts (eg, 1 part, 2 parts, 3 parts, etc.) of color powder.

[0070] In a second aspect, the present invention provides a method for preparing the solvent-free, environmentally friendly UV fast-curing coating as described in the first aspect, the preparation method comprising the following steps:

[0071] UV fast-curing resin, defoaming agent, leveling agent and dispersant are added into a dispersion kettle and stirred, and then glass-coated silver powder, pearlescent pigment, aluminum powder, color powder and hand feeling agent are added and stirred again to obtain the solvent-free environmentally friendly UV fast-curing coating.

[0072] Preferably, the stirring temperature is 10-40°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc.

[0073] Preferably, the stirring speed is 600-800 rpm, for example, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, etc.

[0074] Preferably, the stirring time is 15-25 minutes, for example, 15 minutes, 20 minutes, 25 minutes, etc.

[0075] Preferably, the rotation speed of the second stirring is 300-500 rpm, for example, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, etc.

[0076] Preferably, the stirring time is 25-35 minutes, such as 25 minutes, 30 minutes, 35 minutes, etc.

[0077] In a second aspect, the present invention provides an application of the solvent-free, environmentally friendly UV fast-curing coating as described in the first aspect in pencil coating, wherein the application method comprises the following steps:

[0078] Using a pencil coating machine, a UV-curable color paint is applied to the surface of the pencil original shaft by a pump coating process, each coating film thickness is 4-6 microns (for example, 4 microns, 4.5 microns, 5 microns, 5.5 microns, 6 microns), and the paint is conveyed to a UV curing machine via a conveyor belt for curing for 8-12 seconds (for example, 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, etc.). The coating and curing are repeated 4-6 times, and then a UV-curable topcoat is pumped on the surface once and cured for 8-12 seconds (for example, 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, etc.) to obtain a pencil with pearlescent and / or metallic effects;

[0079] Among them, the UV light curing paint is the solvent-free environmentally friendly UV fast curing paint described in the first aspect, and the solvent-free environmentally friendly UV fast curing paint includes color powder, and any one or a combination of at least two of glass-coated silver powder, pearlescent pigment, and aluminum powder. The difference between the UV light curing paint and the UV light curing paint is that the UV light curing paint does not contain glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder.

[0080] The solvent-free, environmentally friendly, UV fast-curing coating provided by the present invention is used as a pencil coating to bring special visual and tactile effects to the pencil. It is different from the oil-based and water-based pencil coatings on the market, makes up for the shortcomings of oil-based and water-based coatings, and achieves special visual (shimmering, color-changing, metallic pearlescent, etc.) and tactile (skin-friendly, soft, etc.) effects.

[0081] In this invention, the UV-curing coating process significantly reduces VOC emissions, lowers energy consumption, and improves production efficiency compared to thermal curing processes for water-based and oil-based paints, significantly contributing to energy conservation and emission reduction. Due to the extremely low volatility of UV-curing coatings, the risk of operator injury is significantly reduced compared to oil-based coatings.

[0082] Preferably, the application method further comprises the following steps after applying a UV-curing varnish to the surface:

[0083] A UV-curable paint with another appearance effect is placed in a container. One end of a pencil is coated with the paint by dipping, with a length of 25-35 mm (e.g., 25 mm, 28 mm, 30 mm, 32 mm, 33 mm, 35 mm, etc.). The pencil is then conveyed to a UV curing machine via a conveyor belt and cured for 8-12 seconds (e.g., 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, etc.). The surface is then coated with a layer of UV-curable topcoat by pump coating and cured for 8-12 seconds (e.g., 8 seconds, 9 seconds, 10 seconds, 11 seconds, 12 seconds, etc.), resulting in a pencil partially having other pearlescent and / or metallic effects. The UV-curable paint with another appearance effect differs from the aforementioned UV-curable paint in the type of color powder, glass-coated silver powder, pearlescent pigment, aluminum powder, etc. added.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] The solvent-free, environment-friendly UV fast-curing coating provided by the present invention is used as a pencil coating. By introducing a UV fast-curing resin and adopting an ultraviolet curing process, VOC emissions are greatly reduced, making it environmentally friendly. The coating is safer during storage and use, reduces the number of coatings, reduces energy consumption, improves production efficiency, and promotes energy conservation and emission reduction. The cured film has a large molecular weight and good dispersion and encapsulation properties for pigments and fillers. Compared with oil-based and water-based pencil coatings, the coating has significantly improved properties such as abrasion resistance, weather resistance, and chemical resistance. When used as a pencil coating, the coating can bring special visual (shimmering, color-changing, metallic pearlescent, etc.) and tactile (skin-friendly, soft, etc.) effects. DETAILED DESCRIPTION

[0086] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0087] Unless otherwise specified, some of the raw materials used in the preparation examples or examples of the present invention are as follows:

[0088] End-hydroxy branched saturated polyester: PA245;

[0089] Organic bismuth catalyst: BiCAT8118;

[0090] Defoaming agent: YCK750;

[0091] Leveling agent: YCK1130;

[0092] Dispersant: BYK145;

[0093] Feeling agent: SY5370.

[0094] Preparation Example 1

[0095] In this preparation example, a UV fast curing resin is provided, and the preparation method includes the following steps:

[0096] (1) Add 20 parts of hydroxyl-terminated branched saturated polyester into a reactor, heat to 100°C, and use a vacuum pump to remove moisture for 1 hour;

[0097] (2) Cooling to 65°C, filling the reactor with nitrogen, slowly adding 32 parts of hexamethylene diisocyanate into the reactor while stirring, and reacting for 20 minutes; after 20 minutes, adding 0.2 parts of organic bismuth catalyst dropwise into the reactor, and continuing the reaction for 1 hour;

[0098] (3) Add 15 parts of hydroxyethyl methacrylate to the reactor and continue the reaction for 30 minutes. Then, raise the temperature to 83°C and keep it warm for 1 hour.

[0099] (4) The temperature was lowered to 40° C., 12 parts of 2-(2-ethoxyethoxy)ethyl acrylate, 2 parts of acryloylmorpholine, and 1 part of 1173 photoinitiator were added to the reactor, and stirred for 30 minutes to obtain the UV fast-curing resin.

[0100] Preparation Example 2

[0101] In this preparation example, a UV fast curing resin is provided, and the preparation method includes the following steps:

[0102] (1) 22 parts of hydroxyl-terminated branched saturated polyester were added to a reactor, heated to 100°C, and vacuumed for 1 hour using a vacuum pump to remove moisture;

[0103] (2) Cooling to 60°C, filling the reactor with nitrogen, slowly adding 35 parts of hexamethylene diisocyanate into the reactor while stirring, and reacting for 20 minutes; after 20 minutes, adding 0.3 parts of organic bismuth catalyst dropwise into the reactor, and continuing the reaction for 1 hour;

[0104] (3) 18 parts of hydroxyethyl methacrylate was added to the reactor and the reaction was continued for 30 minutes. The temperature was then raised to 80°C and kept at this temperature for 1 hour.

[0105] (4) The temperature was lowered to 40° C., 14 parts of 2-(2-ethoxyethoxy)ethyl acrylate, 2 parts of acryloylmorpholine, and 1.6 parts of 1173 photoinitiator were added to the reactor, and stirred for 30 minutes to obtain the UV fast-curing resin.

[0106] Preparation Example 3

[0107] In this preparation example, a UV fast curing resin is provided, and the preparation method includes the following steps:

[0108] (1) Add 25 parts of hydroxyl-terminated branched saturated polyester into a reactor, heat to 100°C, and use a vacuum pump to remove moisture for 1 hour;

[0109] (2) Cooling to 70°C, filling the reactor with nitrogen, slowly adding 35 parts of hexamethylene diisocyanate into the reactor while stirring, and reacting for 20 minutes; after 20 minutes, adding 0.5 parts of organic bismuth catalyst dropwise into the reactor, and continuing the reaction for 1 hour;

[0110] (3) Add 20 parts of hydroxyethyl methacrylate to the reactor and continue the reaction for 30 minutes. Then raise the temperature to 85°C and keep it warm for 1 hour.

[0111] (4) The temperature was lowered to 40° C., 15 parts of 2-(2-ethoxyethoxy)ethyl acrylate, 5 parts of acryloylmorpholine, and 2 parts of 1173 photoinitiator were added to the reactor, and stirred for 30 minutes to obtain the UV fast-curing resin.

[0112] Preparation Example 4

[0113] In this preparation example, a UV fast curing resin is provided, and the preparation method includes the following steps:

[0114] (1) 30 parts of hydroxyl-terminated branched saturated polyester were added to a reactor, heated to 100°C, and vacuumed for 1 hour using a vacuum pump to remove moisture;

[0115] (2) Cooling to 65°C, filling the reactor with nitrogen, slowly adding 34 parts of hexamethylene diisocyanate into the reactor while stirring, and reacting for 20 minutes; after 20 minutes, adding 0.2 parts of organic bismuth catalyst dropwise into the reactor, and continuing the reaction for 1 hour;

[0116] (3) Add 15 parts of hydroxyethyl methacrylate to the reactor and continue the reaction for 30 minutes. Then raise the temperature to 82°C and keep it warm for 1 hour.

[0117] (4) The temperature was lowered to 40° C., 20 parts of 2-(2-ethoxyethoxy)ethyl acrylate, 5 parts of acryloylmorpholine, and 2 parts of 1173 photoinitiator were added to the reactor, and stirred for 30 minutes to obtain the UV fast-curing resin.

[0118] Comparative Preparation Example 1

[0119] The only difference between this comparative preparation example and Preparation Example 1 is that in step (4), 2-(2-ethoxyethoxy)ethyl acrylate is replaced by isobornyl methacrylate in equal parts by weight.

[0120] Comparative Preparation Example 2

[0121] The only difference between this comparative preparation example and Preparation Example 1 is that acryloylmorpholine is not added in step (4).

[0122] Example 1-A

[0123] In this embodiment, a solvent-free, environmentally friendly UV fast-curing coating is provided, and a preparation method thereof comprises the following steps:

[0124] At 25°C, stirring speed is 700 rpm, 85 parts of UV fast curing resin, 0.2 parts of defoaming agent, 1 part of leveling agent, and 0.2 parts of dispersant are added to the dispersion kettle in sequence and stirred. After stirring for 20 minutes, 3 parts of glass-coated silver powder, 3 parts of pearlescent pigment, 1 part of aluminum powder, 2 parts of color powder, and 0.5 parts of feeling agent are added under stirring condition of 400 rpm and stirred for 30 minutes;

[0125] The UV fast-curing resin is provided by Preparation Example 1, the glass-coated silver powder is U3500, the pearlescent pigment is SCL305, the aluminum powder is NPW2600, and the color powder is transparent blue 737.

[0126] Example 1-B

[0127] The only difference between this embodiment and embodiment 1-A is that glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder are not added.

[0128] Example 2-A

[0129] In this embodiment, a solvent-free, environmentally friendly UV fast-curing coating is provided, and a preparation method thereof comprises the following steps:

[0130] At 25°C, stirring speed is 600 rpm, 90 parts of UV fast curing resin, 0.3 parts of defoaming agent, 0.5 parts of leveling agent, and 0.1 parts of dispersant are added to the dispersion kettle in sequence and stirred. After stirring for 20 minutes, 5 parts of glass-coated silver powder, 6 parts of pearlescent pigment, 1.5 parts of aluminum powder, 2 parts of color powder, and 0.8 parts of feel agent are added under stirring condition of 300 rpm and stirred for 30 minutes;

[0131] The UV fast-curing resin is provided by Preparation Example 2, the glass-coated silver powder is U3500, the pearlescent pigment is SCL305, the aluminum powder is NPW2600, and the color powder is transparent purple 840.

[0132] Example 2-B

[0133] The only difference between this embodiment and embodiment 2-A is that glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder are not added.

[0134] Example 3-A

[0135] In this embodiment, a solvent-free, environmentally friendly UV fast-curing coating is provided, and a preparation method thereof comprises the following steps:

[0136] At 25°C, stirring speed is 800 rpm, 82 parts of UV fast curing resin, 0.5 parts of defoaming agent, 0.8 parts of leveling agent, and 0.5 parts of dispersant are added to the dispersion kettle in sequence and stirred. After stirring for 20 minutes, 6 parts of glass-coated silver powder, 4 parts of pearlescent pigment, 2 parts of aluminum powder, 2 parts of color powder, and 0.3 parts of feel agent are added under stirring condition of 500 rpm and stirred for 30 minutes;

[0137] The UV fast-curing resin is provided by Preparation Example 3, the glass-coated silver powder is U3500, the pearlescent pigment is SCL305, the aluminum powder is NPW2600, and the color powder is transparent yellow 8802.

[0138] Example 3-B

[0139] The only difference between this embodiment and embodiment 3-A is that glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder are not added.

[0140] Example 4-A

[0141] In this embodiment, a solvent-free, environmentally friendly UV fast-curing coating is provided, and a preparation method thereof comprises the following steps:

[0142] At 25°C, stirring speed is 800 rpm, 88 parts of UV fast curing resin, 0.2 parts of defoaming agent, 0.6 parts of leveling agent, and 0.3 parts of dispersant are added to the dispersion kettle in sequence and stirred. After stirring for 20 minutes, 3 parts of glass-coated silver powder, 5 parts of pearlescent pigment, 1 part of aluminum powder, 2 parts of color powder, and 0.5 parts of feeling agent are added under stirring condition of 500 rpm and stirred for 30 minutes;

[0143] The UV fast-curing resin is provided by Preparation Example 4, the glass-coated silver powder is U3500, the pearlescent pigment is SCL305, the aluminum powder is NPW2600, and the color powder is transparent green 852.

[0144] Example 4-B

[0145] The only difference between this embodiment and embodiment 4-A is that glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder are not added.

[0146] Comparative Example 1-A

[0147] The only difference between this comparative example and Example 1-A is that the UV fast-curing resin is provided by Comparative Preparation Example 1.

[0148] Comparative Example 1-B

[0149] The only difference between this comparative example and comparative example 1-A is that no glass-coated silver powder, pearlescent pigment, aluminum powder, or color powder is added.

[0150] Comparative Example 2-A

[0151] The only difference between this comparative example and Example 1-A is that the UV fast-curing resin is provided by Comparative Preparation Example 2.

[0152] Comparative Example 2-B

[0153] The only difference between this comparative example and comparative example 2-A is that no glass-coated silver powder, pearlescent pigment, aluminum powder, or color powder is added.

[0154] Application Example 1

[0155] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 1-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 μm. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 1-B) was drawn once on the surface. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This resulted in a pencil with blue pearlescent and metallic shimmer effects.

[0156] Application Example 2

[0157] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 2-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 μm. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 2-B) was drawn once on the surface. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This resulted in a pencil with purple pearlescent and metallic shimmer effects.

[0158] Application Example 3

[0159] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 3-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 μm. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 3-B) was drawn once on the surface. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This resulted in a pencil with yellow pearlescent and metallic shimmer effects.

[0160] Application Example 4

[0161] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 4-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 μm. The pencil shaft was then transferred to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 4-B) was drawn once on the surface. The pencil shaft was then transferred to a UV curing machine via a conveyor belt and cured for 10 seconds to obtain a pencil with green pearlescent and metallic shimmer effects.

[0162] A UV-curable color paint with another appearance effect (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 1-A) was placed in a tray, and one end of a pencil was coated with the paint by dipping, with a length of 25 mm. The pencil was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The surface was then coated with a layer of UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Example 1-B) by pump coating, and conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This produced a pencil partially having another blue pearlescent and metallic glitter effect.

[0163] Comparative Application Example 1

[0164] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Comparative Example 1-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 microns. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Comparative Example 1-B) was drawn once on the surface. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This resulted in a pencil with blue pearlescent and metallic glitter effects.

[0165] Comparative Application Example 2

[0166] Using a pencil coating machine, a UV-curable color paint (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Comparative Example 2-A) was applied to the surface of the pencil shaft by a draw coating process. Each coating film had a thickness of 5 microns. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. The coating and curing were repeated 5 times. Finally, a UV-curable topcoat (i.e., the solvent-free, environmentally friendly UV fast-curing paint provided in Comparative Example 2-B) was drawn once on the surface. The pencil shaft was then conveyed to a UV curing machine via a conveyor belt and cured for 10 seconds. This resulted in a pencil with blue pearlescent and metallic shimmer effects.

[0167] Performance tests were conducted on pencils corresponding to the use cases and comparative application examples (since the pencil coatings were from the examples, the actual tests were conducted on the coatings provided in Examples 1-B to 4-B, Comparative Example 1-B, and Comparative Example 2-B). The test method is as follows:

[0168] (1) Pencil paint film hardness: Use a 15 μm film-making device to scrape the paint onto a glass plate, cure it in a UV curing machine for 10 seconds, and then use a pencil hardness tester with a 1 kg weight to test the pencil paint film hardness;

[0169] (2) Cracking rate: Use a 15-micron film-making device to scrape the paint onto a polished basswood board, cure it in a UV curing machine for 10 seconds, and then place it in a constant temperature and humidity chamber at a temperature of 45°C and a humidity of 80% for 15 days to observe the degree of cracking of the paint film;

[0170] (3) Solvent resistance: Use a 15-micron film-making device to scrape the paint onto a glass plate, cure it in a UV curing machine for 10 seconds, wipe it with gauze soaked in butanone, and record the number of wipes when the paint film is damaged.

[0171] The performance test results are shown in Table 1.

[0172] Table 1

[0173]

[0174] As can be seen from Table 1, the pencils prepared by using the solvent-free, environmentally friendly UV fast-curing coating provided by the embodiment of the present invention as the pencil coating have a paint film with suitable hardness and good wear resistance, weather resistance, and chemical resistance.

[0175] Compared with Application Example 1, the pencil provided in Comparative Application Example 1 is prone to cracking under high temperature and high humidity, causing irreversible damage to the pencil; the paint film of the pencil provided in Comparative Application Example 2 has low hardness and is easily scratched and damaged. When contaminated with oil, the paint film will swell and soften, resulting in color loss.

[0176] The applicant declares that while the above-described embodiments illustrate the solvent-free, environmentally friendly UV fast-curing coating, its preparation method, and its application, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A solvent-free, environmentally friendly UV fast-curing coating for pencil coating, characterized in that: The raw materials for preparing the solvent-free environmentally friendly UV fast curing coating include the following components in parts by weight: 80-90 parts of UV fast curing resin; 0.1-1 part of hand feeling agent; Leveling agent 0.2-1 part; Defoaming agent 0.2-1 part; Dispersant 0.1-0.5 parts; The raw materials for preparing the solvent-free environmentally friendly UV fast curing coating also include any one or a combination of at least two of glass-coated silver powder, pearlescent pigment, and aluminum powder, and also include color powder; The raw materials for preparing the UV fast curing resin include the following components in parts by weight: 20-30 parts of hydroxyl-terminated branched saturated polyester; 15-20 parts of hydroxyethyl methacrylate; 30-40 parts of isocyanate; 2-(2-ethoxyethoxy)ethyl acrylate 10-20 parts; Acryloylmorpholine 2-5 parts; 0.1-0.5 parts of organic bismuth catalyst; 1-3 parts of photoinitiator; The UV fast curing resin is prepared by the following method: (1) Adding the terminal hydroxyl branched saturated polyester into a reaction kettle, heating, and vacuuming to remove the moisture therein; (2) Cooling down, filling the reactor with inert gas, then adding isocyanate to react, and then adding an organic bismuth catalyst to continue the reaction; (3) Adding hydroxyethyl methacrylate into the reaction kettle, continuing the reaction, increasing the temperature, and maintaining the temperature; (4) Cooling the mixture, adding 2-(2-ethoxyethoxy)ethyl acrylate, acryloylmorpholine, and a photoinitiator, and stirring the mixture to obtain the UV fast-curing resin.

2. The solvent-free, environmentally friendly UV fast curing coating according to claim 1, characterized in that: The isocyanate includes hexamethylene diisocyanate; The photoinitiator includes 1173 photoinitiator.

3. The solvent-free, environmentally friendly UV fast curing coating according to claim 1, characterized in that: The heating in step (1) is heating to 100-110° C. The vacuuming time in step (1) is 0.5-1.5 hours; The cooling in step (2) is to cool to 60-70°C; The reaction time of step (2) is 15-25 minutes; The reaction time in step (2) is 0.5-1.5 hours; The reaction time in step (3) is 20-40 minutes; The heating in step (3) is to heat the temperature to 80-85°C; The insulation time in step (3) is 0.5-1.5 hours; The cooling in step (4) is to cool to 35-45°C; The stirring time in step (4) is 20-40 minutes.

4. The solvent-free environmentally friendly UV fast curing coating according to claim 1, characterized in that: The hand feeling agent includes silicone resin; The leveling agent includes polydimethylsiloxane; The defoamer comprises a modified polysiloxane defoamer; The dispersant includes polyacrylamide.

5. The solvent-free, environmentally friendly UV fast curing coating according to claim 1, characterized in that: The glass-coated silver powder is a glass-coated silver sheet; The weight proportion of the glass-coated silver powder is 3-6 parts; The pearlescent pigment is a mica flake coated with a metal oxide; The weight proportion of the pearlescent pigment is 3-6 parts; The aluminum powder is a resin-coated aluminum sheet; The weight proportion of the aluminum powder is 1-3 parts.

6. The solvent-free environmentally friendly UV fast curing coating according to claim 1, characterized in that: The raw materials for preparing the solvent-free environmentally friendly UV fast-curing coating include 1 to 3 parts of color powder.

7. A method for preparing a solvent-free, environmentally friendly UV fast-curing coating according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: UV fast-curing resin, defoamer, leveling agent and dispersant are added into a dispersion kettle and stirred, and then glass-coated silver powder, pearlescent pigment, aluminum powder, color powder and hand-feeling agent are added and stirred again to obtain the solvent-free environmentally friendly UV fast-curing coating.

8. The preparation method according to claim 7, characterized in that: The stirring temperature is 10-40°C; The stirring speed is 600-800 rpm; The stirring time is 15-25 minutes; The rotation speed of the second stirring is 300-500 rpm; The stirring time is 25-35 minutes.

9. Application of the solvent-free, environmentally friendly UV fast curing coating as claimed in any one of claims 1 to 6 in pencil coating, characterized in that: The method of application comprises the following steps: Using a pencil coating machine, a UV-curable color paint is applied to the surface of the pencil original rod by a pumping process, each coating film thickness is 4-6 microns, and then the paint is transferred to the UV curing machine through a conveyor belt for curing for 8-12 seconds, and the coating and curing are repeated 4-6 times, and then a UV-curable varnish is pumped on the surface once and cured for 8-12 seconds to obtain a pencil with pearlescent and / or metallic special effects; Wherein, the UV-curable paint is the solvent-free environmentally friendly UV fast-curing paint as described in any one of claims 1 to 6, and the difference between the UV-curable paint and the UV-curable paint is that the UV-curable paint does not contain glass-coated silver powder, pearlescent pigment, aluminum powder, and color powder; In the application method, after applying a UV-curing varnish once on the surface, the following steps are also included: A UV-curable color paint with another appearance effect is placed in a container, and one end of the pencil is coated with the paint by a dipping process, with a length of 25-35 mm, and then conveyed to a UV curing machine by a conveyor belt for curing for 8-12 seconds, and then a layer of UV-curable varnish is coated on the surface by a pumping process, and cured for 8-12 seconds, to obtain a pencil with other pearlescent and / or metallic special effects.

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