An oily glittery core, a preparation method and application thereof

Abstract

This invention belongs to the field of stationery technology, and relates to an oil-based iridescent pen refill, its preparation method, and its application. The raw materials of the oil-based iridescent pen refill include specific proportions of composite wax, clay, pigment, plant wax, and adhesive. The composite wax is obtained by hydrogenating soybean wax to produce hydrogenated soybean wax, and then performing an ester exchange reaction between the obtained hydrogenated soybean wax and rice bran wax. By introducing the above-mentioned specific composite wax and plant wax, the compatibility and thixotropy of the system are effectively improved. This allows the pen refill to maintain a high softening point while possessing smoothness due to instantaneous rheological changes under pressure. It also achieves non-bleeding at high temperatures and has excellent folding resistance, bright color rendering, and strong adhesion. At the same time, the raw materials used are renewable, biodegradable, odorless, low in VOC, safe, and non-toxic during production and use.

Description

Technical Field

[0001] This invention belongs to the field of stationery technology, and relates to an oil-based iridescent pen refill, its preparation method, and its application. Background Technology

[0002] Writing and drawing tools are important carriers of human culture and creative expression. Among them, oil-based coloring pens are favored by artists, designers, educators and painting enthusiasts for their rich and full colors, strong covering power, ability to mix and layer colors, and resistance to fading. They are widely used in art education, professional creation, and journal decoration.

[0003] However, the core technologies of mainstream oil-based color-enhancing pen refills on the market still have the following significant drawbacks: ① The contradiction between raw materials and environmental friendliness: Traditional oil-based color-enhancing pen refills rely heavily on petroleum derivatives (such as mineral oil / paraffin / polyethylene wax, etc.). This not only poses a challenge to the sustainability of raw materials, but its production process and discarded refills may also burden the environment. ② Safety and health issues: Especially for products targeting the children's market, consumers are extremely concerned about the safety of pen refill ingredients (such as whether they contain heavy metals, harmful volatile organic compounds, allergens, etc.). There are potential safety concerns regarding traditional petroleum-based raw materials and certain synthetic additives. ③ The challenge of performance balance: the contradiction between hardness and color rendering, smoothness and adhesion, and the limitation of functions.

[0004] Therefore, to address the aforementioned technical issues, an environmentally friendly oil-based color pen refill that achieves a balance between pen refill hardness, application smoothness, color rendering, and adhesion, while also possessing excellent high-temperature and high-humidity resistance, should be developed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an oil-based iridescent pen refill, its preparation method, and its application. The oil-based iridescent pen refill uses plant wax as a base, exhibiting extreme smoothness, excellent fold resistance, vibrant color rendering, and strong adhesion. Furthermore, the raw materials are renewable and biodegradable, and the production and use process is odorless, low in VOCs, and safe and non-toxic.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides an oil-based iridescent pen refill, wherein the material of the oil-based iridescent pen refill comprises the following components in parts by weight: 15-30 parts by weight of compound wax; 40-65 parts by weight of clay; 5-10 parts by weight of color powder; 5-15 parts by weight of plant wax; 1-5 parts by weight of adhesive; The composite wax is obtained by hydrogenating soybean wax to produce hydrogenated soybean wax, and then subjecting the resulting hydrogenated soybean wax to an ester exchange reaction with rice bran wax.

[0007] The oil-based iridescent pen refill provided by this invention effectively improves the compatibility and thixotropy of the system by introducing a specific composite wax and plant wax. The composite wax is a high-melting-point wax that provides structural hardness, while the plant wax is a low-melting-point wax that provides smoothness. This allows the pen refill to maintain a high softening point while possessing the smoothness of instantaneous flow under pressure. It also achieves high-temperature non-bleeding, giving the pen refill a "hard but not brittle, soft but not sticky" feel when drawing or writing. It also has excellent fold resistance, vivid color rendering, and strong adhesion. Moreover, the raw materials are renewable and biodegradable, and the production and use process is odorless, low in VOCs, safe and non-toxic.

[0008] The amount of the composite wax can be 15 parts by weight, 17 parts by weight, 19 parts by weight, 21 parts by weight, 23 parts by weight, 25 parts by weight, 27 parts by weight, 29 parts by weight, or 30 parts by weight, etc.

[0009] The amount of clay used can be 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, 60 parts by weight, 62 parts by weight, or 65 parts by weight, etc.

[0010] The amount of pigment used can be 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, or 10 parts by weight, etc.

[0011] The amount of plant wax used can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, or 15 parts by weight, etc.

[0012] The amount of adhesive used can be 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, or 5 parts by weight, etc.

[0013] Preferably, the mass ratio of soybean wax to rice bran wax is (1~20):(1~20), for example, 1:1, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 20:1, 18:1, 16:1, 14:1, 12:1, 10:1, 8:1, 6:1, 4:1 or 2:1, etc.

[0014] Preferably, the composite wax is prepared by the following method, which includes the following steps: (1) Soybean wax is hydrogenated under the condition of hydrogenation catalyst to obtain hydrogenated soybean wax; (2) The hydrogenated soybean wax obtained in step (1) and rice bran wax are subjected to transesterification reaction under the condition of transesterification catalyst to obtain the composite wax.

[0015] Preferably, the hydrogenation catalyst in step (1) comprises a supported nickel catalyst.

[0016] In this invention, there are no special requirements for the specific type of the supported nickel catalyst; conventional products in the art can be selected.

[0017] Preferably, the temperature of the hydrogenation reaction in step (1) is 150~200℃, for example 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃.

[0018] Preferably, the hydrogenation reaction in step (1) is carried out at a hydrogen pressure of 0.2 to 0.5 MPa (e.g., 0.2 MPa, 0.22 MPa, 0.24 MPa, 0.26 MPa, 0.28 MPa, 0.3 MPa, 0.32 MPa, 0.34 MPa, 0.36 MPa, 0.38 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa).

[0019] Preferably, the hydrogenation reaction in step (1) ends when the iodine value of the system reaches 20~40 g I2 / 100 g (e.g., 20 g I2 / 100 g, 22 g I2 / 100 g, 24 g I2 / 100 g, 26 g I2 / 100 g, 28 g I2 / 100 g, 30 g I2 / 100 g, 32 g I2 / 100 g, 34 g I2 / 100 g, 36 g I2 / 100 g, 38 g I2 / 100 g or 40 g I2 / 100 g, etc.).

[0020] Preferably, the transesterification catalyst in step (2) comprises sodium methoxide.

[0021] Preferably, the transesterification reaction in step (2) is carried out under inert gas protection conditions.

[0022] Preferably, the temperature of the transesterification reaction in step (2) is 180~220℃, such as 180℃, 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃ or 220℃.

[0023] Preferably, the transesterification reaction time in step (2) is 1 to 3 h, for example, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h.

[0024] Preferably, the clay includes kaolin and / or bentonite.

[0025] Preferably, the pigment includes any one or a combination of at least two of the following: scarlet powder, fast yellow, phthalocyanine blue, carbon black, or titanium dioxide.

[0026] Preferably, the plant wax includes rice bran wax.

[0027] Preferably, the plant wax also includes coconut wax and / or tree wax.

[0028] Preferably, the adhesive comprises sodium carboxymethyl cellulose and / or hydroxypropyl cellulose.

[0029] Preferably, the material of the oil-based iridescent pen refill also includes 1 to 2 parts by weight (e.g., 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, or 2 parts by weight, etc.) of dispersant.

[0030] Preferably, the dispersant comprises sodium polyacrylate dispersant or phosphate ester dispersant.

[0031] Preferably, the material of the oil-based iridescent pen refill also includes 1 to 2 parts by weight (e.g., 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, or 2 parts by weight, etc.) of a wetting agent.

[0032] Preferably, the wetting agent comprises lauryl alcohol polyoxyethylene ether.

[0033] In a second aspect, the present invention provides a method for preparing an oil-based iridescent pen refill as described in the first aspect, the method comprising: mixing a composite wax, clay, pigment, plant wax, adhesive, optionally a dispersant and optionally a wetting agent in water, followed by grinding, hydraulic pressing and drying to obtain the oil-based iridescent pen refill.

[0034] It should be noted that the aforementioned composite wax and plant wax are both melted liquid waxes.

[0035] Preferably, the mixing temperature is 40~50℃, such as 40℃, 42℃, 44℃, 46℃, 48℃ or 50℃.

[0036] Preferably, the mixing time is 120-150 min, such as 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, or 150 min.

[0037] Preferably, the grinding is performed in a three-roll mill.

[0038] Preferably, the drying temperature is 40~60℃, such as 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃ or 60℃.

[0039] Preferably, the drying time is 70-80 hours, such as 72 hours, 74 hours, 76 hours, 78 hours, or 80 hours.

[0040] Thirdly, the present invention provides a colored pencil, the colored pencil comprising the oil-based colored lead as described in the first aspect.

[0041] Compared with the prior art, the present invention has the following beneficial effects: (1) The oil-based iridescent pen core provided by the present invention maintains a high softening point and has the smoothness of instantaneous flow under pressure. It can also achieve the characteristic of not bleeding at high temperature. When drawing or writing, it has a "hard but not brittle, soft but not sticky" feel. It also has excellent fold resistance. The pen core has bright and full colors, strong covering power and strong adhesion. It not only performs well on paper, but also adheres well on a variety of non-absorbent surfaces such as canvas, wood, ceramics and glass, thus expanding the creative medium. (2) The core raw material of the oil-based iridescent pen refill provided by this invention is derived from plants, which is renewable and reduces the carbon footprint of the product. It conforms to the global green consumption trend. From production to disposal, the negative impact on the environment is significantly reduced. Moreover, the production process and the final product are almost odorless and do not contain any chemical components that are harmful to the human body. It has passed strict safety certification and is an ideal choice for children and sensitive groups. (3) The oil-based iridescent pen core provided by the present invention can be used to develop professional-grade products suitable for solvent blending (creating watercolor effects), which can meet the diverse needs of artists and designers. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] The detailed information of some of the raw materials involved in the following specific implementation methods is shown below: (1) Soybean wax: purchased from Nanjing Fangnaite, brand name FN-PureSoy 45; (2) Rice bran wax: purchased from Hecai Chemical Technology, brand name BIO-R03; (3) Coconut wax: purchased from Nanjing Fangnaite, brand name FN-CW38; (4) Tree wax: purchased from Nanjing Fangnaite, brand name FN-JW50; (5) Clay: Purchased from Guangdong Xinbangle, brand name BM C2; (6) Bright red powder: PR254; (7) Sunlight-resistant yellow: PY13; (8) Phthalocyanine Blue: PB15:3; (9) Carbon black: Carbon M-100; (10) Titanium dioxide: Ti Pure R900; (11) Wetting agent: lauryl alcohol polyoxyethylene ether, purchased from Shanghai Qi'ai, brand name W-1; (12) Dispersant: Phosphate ester dispersant, BYK145; (13) Supported nickel catalyst: commercially available.

[0044] Preparation Example 1 A composite wax, the preparation method of which includes the following steps: (1) Eight parts by weight of soybean wax and 0.12 parts by weight of supported nickel catalyst were hydrogenated at 180°C and 0.3 MPa hydrogen pressure until the system reached a point value of 30 g I2 / 100 g to obtain hydrogenated soybean wax. (2) The hydrogenated soybean wax obtained in step (1) and 15 parts by weight of rice bran wax are mixed, and 0.3 parts by weight of sodium methoxide are added. The mixture is stirred and reacted for 2 h under argon protection and at 200°C to obtain the composite wax.

[0045] Preparation Example 2 A composite wax, the preparation method of which includes the following steps: (1) 8.7 parts by weight of soybean wax and 0.08 parts by weight of supported nickel catalyst were hydrogenated at 160°C and 0.5 MPa hydrogen pressure until the system reached 25 g I2 / 100 g to obtain hydrogenated soybean wax. (2) The hydrogenated soybean wax obtained in step (1) and 16.3 parts by weight of rice bran wax are mixed, and 0.2 parts by weight of sodium methoxide are added. The mixture is stirred and reacted for 1.5 h under argon protection and at 190°C to obtain the composite wax.

[0046] Preparation Example 3 A composite wax, the preparation method of which includes the following steps: (1) 10.5 parts by weight of soybean wax and 0.2 parts by weight of supported nickel catalyst were hydrogenated at 190°C and 0.2 MPa hydrogen pressure until the system reached 35 g I2 / 100 g to obtain hydrogenated soybean wax. (2) The hydrogenated soybean wax obtained in step (1) and 19.5 parts by weight of rice bran wax are mixed, and 0.4 parts by weight of sodium methoxide are added. The mixture is stirred and reacted for 2.5 h under argon protection and at 210°C to obtain the composite wax.

[0047] Preparation Example 4 A composite wax differs from Preparation Example 1 only in that the amount of rice bran wax used is 0.1 parts by weight, while the other substances, amounts, and preparation methods are the same as in Preparation Example 1.

[0048] Preparation Example 5 A composite wax differs from Preparation Example 1 only in that the amount of rice bran wax used is 170 parts by weight, while the other substances, amounts, and preparation methods are the same as in Preparation Example 1.

[0049] Examples 1-7 Examples 1-7 provide an oil-based iridescent pen refill, the components and amounts of which are shown in Table 1. In Table 1, the amount of each component is in "parts by weight". Table 1 The preparation methods of the oil-based iridescent pen refills provided in Examples 1-7 include the following steps: The composite wax and plant wax are melted together, and then a dispersant and wetting agent are added and stirred for 10 minutes. Clay, red powder, adhesive and water are then added and stirred in a high-speed mixing tank for 2 hours. After that, the mixture is ground in a three-roll mill and then hydraulically extruded under a pressure of 20 MPa. Finally, it is dried at 50°C for 72 hours to control the moisture content of the pen refill to 0.8%, thus obtaining the oil-based iridescent pen refill.

[0050] Comparative Example 1 An oil-based iridescent pen refill differs from Example 1 in that 15 parts by weight of rice bran wax and 8 parts by weight of soybean wax are used to replace the composite wax, while the other components and amounts are the same as in Example 1. The preparation method includes: melting rice bran wax, soybean wax and plant wax, adding dispersant, wetting agent and adhesive and stirring for 10 min, then adding clay, red powder and water and stirring in a high-speed mixing tank for 2 h, then grinding in a three-roll mill, then hydraulically extruding the core under a pressure of 20 MPa, and finally drying at 50℃ for 72 h to control the moisture content of the pen core at 0.8% to obtain the oil-based iridescent pen core.

[0051] Comparative Example 2 An oil-based iridescent pen refill differs from Example 2 in that 16.3 parts by weight of rice bran wax and 8.7 parts by weight of soybean wax are used to replace the composite wax, while the other components and amounts are the same as in Example 2. The preparation method includes: melting rice bran wax, soybean wax and plant wax, adding dispersant, wetting agent and adhesive and stirring for 10 min, then adding clay, red powder and water and stirring in a high-speed mixing tank for 2 h, then grinding in a three-roll mill, then hydraulically extruding the core under a pressure of 20 MPa, and finally drying at 50℃ for 72 h to control the moisture content of the pen core at 0.8% to obtain the oil-based iridescent pen core.

[0052] Comparative Example 3 An oil-based iridescent pen refill differs from Example 3 in that 19.5 parts by weight of rice bran wax and 10.5 parts by weight of soybean wax are used to replace the composite wax, while the other components and amounts are the same as in Example 3. The preparation method includes: melting rice bran wax, soybean wax and plant wax, adding dispersant, wetting agent and adhesive and stirring for 10 min, then adding clay, red powder and water and stirring in a high-speed mixing tank for 2 h, then grinding in a three-roll mill, then hydraulically extruding the core under a pressure of 20 MPa, and finally drying at 50℃ for 72 h to control the moisture content of the pen core at 0.8% to obtain the oil-based iridescent pen core.

[0053] Comparative Example 4 An oil-based iridescent pen refill differs from Example 3 in that no composite wax is added, while the other components, dosages, and preparation methods are the same as in Example 3.

[0054] Comparative Example 5 An oil-based iridescent pen refill differs from Example 3 in that it does not contain plant wax, while the other components, dosages, and preparation methods are the same as in Example 3.

[0055] Performance testing: (1) Lead core softening point: The test was conducted in accordance with the soft point test method in QB / T 2586-2014.

[0056] (2) Smoothness: Apply a long strip of color continuously on a specific piece of paper, and judge the smoothness by comparing the frictional resistance between the pen tip and the paper surface through tactile feedback.

[0057] (3) Color rendering: The color rendering is determined by applying the same amount of pressure to a standard white paper once or multiple times, based on the fullness of the line color and whether the color is rich and uniform.

[0058] (4) Adhesion: The adhesion is determined by applying the same force to the paper and observing whether the applied color block can completely cover the paper without leaving any white or the coating opaque.

[0059] (5) High temperature and high humidity resistance: Take 20 pencils each (the pencil preparation method is as follows: ① Plane a semi-circular groove in the board according to the diameter of the lead core; ② Apply glue to the grooves of two grooved wooden boards, put the lead core into the groove of one of the wooden boards, and then cover it with the other wooden board, and press the two wooden boards firmly together by a certain pressure; ③ Plane the barrel. Hexagonal, triangular and round barrels can be made according to requirements. ④ Paint the barrel with the specified color; ⑤ Sharpen the tip to form a geometric cone shape so that the lead core is exposed in the barrel), and place them in a constant temperature and humidity chamber at 45℃ and 80% humidity for 14 days, and observe whether there are any problems such as cracking, deformation and breakage of the lead core.

[0060] (6) High temperature resistance: Take 20 pencils (the preparation method of the pencils is the same as above), place them in a drying oven at 55℃ for 24 h, and observe whether the pencil tip and lead core are deformed, broken, or whether the color seeps out.

[0061] The pen refills provided in Examples 1-7 and Comparative Examples 1-5 were tested according to the above testing method. The test results are shown in Table 2. Table 2 According to the data in Table 2: The oil-based iridescent pen refills provided in Examples 1-3 have a suitable softening point (71-75.5℃), and have the advantages of being smooth, having bright and full colors, strong coverage and strong adhesion. They also have excellent resistance to high temperature and humidity and high temperature resistance.

[0062] Comparing Example 1 with Comparative Example 1, Example 2 with Comparative Example 2, and Example 3 with Comparative Example 3, it can be seen that simply mixing plant wax physically leads to a decrease in the softening point of the final oil-based iridescent pen core, and poor resistance to high temperature and humidity and high temperature.

[0063] Further comparison of Example 3 and Comparative Examples 4-5 shows that the oil-based iridescent pen refill without added composite wax (Comparative Example 4) has a lower softening point, poorer smoothness, and poorer resistance to high temperature and humidity and high temperature; while the oil-based iridescent pen refill without added plant wax (Comparative Example 5) has poorer smoothness, color rendering, and adhesion.

[0064] Further comparison of Examples 1 and 4-7 also shows that the type of plant wax and the amount of rice bran wax in the composite wax will affect the smoothness, color rendering, adhesion and weather resistance of the final oil-based iridescent pen refill.

[0065] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An oil-based iridescent pen refill, characterized in that, The raw materials for the oil-based iridescent pen refill include the following components by weight: 15-30 parts by weight of compound wax; 40-65 parts by weight of clay; 5-10 parts by weight of color powder; 5-15 parts by weight of plant wax; 1-5 parts by weight of adhesive; The composite wax is obtained by hydrogenating soybean wax to produce hydrogenated soybean wax, and then subjecting the resulting hydrogenated soybean wax to an ester exchange reaction with rice bran wax.

2. The oil-based iridescent pen refill according to claim 1, characterized in that, The mass ratio of soybean wax to rice bran wax is (1~20):(1~20); Preferably, the composite wax is prepared by the following method, which includes the following steps: (1) Soybean wax is hydrogenated under the condition of hydrogenation catalyst to obtain hydrogenated soybean wax; (2) The hydrogenated soybean wax obtained in step (1) and rice bran wax are subjected to transesterification reaction under the condition of transesterification catalyst to obtain the composite wax; Preferably, the hydrogenation catalyst in step (1) comprises a supported nickel catalyst; Preferably, the temperature of the hydrogenation reaction in step (1) is 150~200℃; Preferably, the hydrogenation reaction in step (1) is carried out under a hydrogen pressure of 0.2~0.5 MPa; Preferably, the hydrogenation reaction in step (1) ends when the iodine value of the system reaches 20~40 g I2 / 100 g; Preferably, the transesterification catalyst in step (2) comprises sodium methoxide; Preferably, the transesterification reaction in step (2) is carried out under inert gas protection conditions; Preferably, the temperature of the transesterification reaction in step (2) is 180~220℃ and the time is 1~3 h.

3. The oil-based iridescent pen refill according to claim 1 or 2, characterized in that, The clay includes kaolin and / or bentonite.

4. The oil-based iridescent pen refill according to any one of claims 1 to 3, characterized in that, The pigments include any one or a combination of at least two of the following: scarlet, lightfast yellow, phthalocyanine blue, carbon black, or titanium dioxide.

5. The oil-based iridescent pen refill according to any one of claims 1 to 4, characterized in that, The plant waxes include rice bran wax; Preferably, the plant wax also includes coconut wax and / or tree wax.

6. The oil-based iridescent pen refill according to any one of claims 1 to 5, characterized in that, The adhesive includes sodium carboxymethyl cellulose and / or hydroxypropyl cellulose.

7. The oil-based iridescent pen refill according to any one of claims 1 to 6, characterized in that, The material of the oil-based iridescent pen refill also includes 1 to 2 parts by weight of dispersant; Preferably, the dispersant comprises sodium polyacrylate dispersant or phosphate ester dispersant; Preferably, the material of the oil-based iridescent pen refill further includes 1-2 parts by weight of a wetting agent; Preferably, the wetting agent comprises lauryl alcohol polyoxyethylene ether.

8. A method for preparing an oil-based iridescent pen refill as described in any one of claims 1 to 7, characterized in that, The preparation method includes: mixing composite wax, clay, pigment, plant wax, adhesive, optionally dispersant and optionally wetting agent in water, followed by grinding, hydraulic pressure and drying to obtain the oil-based iridescent pen refill.

9. The preparation method according to claim 8, characterized in that, The mixing temperature is 40~50℃, and the time is 120~150 min; Preferably, the grinding is performed in a three-roll mill.

10. A colorful pencil, characterized in that, The iridescent pencil includes the oil-based iridescent pencil lead as described in any one of claims 1 to 7.

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