Non-toxic and harmless colored pencil leads and preparation method thereof

Abstract

The present invention discloses a non-toxic and harmless colored pencil lead and a preparation method thereof. The colored pencil lead is made of the following components: fruit and vegetable powder, food-grade titanium dioxide, polylactic acid, adipic acid butanediol ester and terephthalic acid butanediol ester copolymer, and food-grade talcum powder. In the present invention, polylactic acid and fruit and vegetable powder are mutually fused and stirred at high temperature, so that the polylactic acid wraps the fruit and vegetable powder to form a color paste film. The addition of adipic acid butanediol ester and terephthalic acid butanediol ester copolymer increases the strength of the pencil lead and is more conducive to the formation of the color paste film. It can not only make the fruit and vegetable powder show color, but also be more heat-resistant, biodegradable, with various colors, and is more suitable for the children's market. When preparing the color paste film, the mixed powder is dispersed by a high-speed disperser to break the intermolecular force, so that the material is more evenly dispersed, the dispersion effect is better, it is not easy to agglomerate and cake, and the use feel is delicate and smooth. The present invention uses a twin-screw extruder to extrude and granulate instead of the traditional core pressing process, with higher efficiency and better stability.

Description

Technical Field

[0001] The present invention relates to pencil leads, in particular to non-toxic and harmless colored pencil leads and a preparation method thereof, belonging to the field of colored pencil leads and their preparation. Background Art

[0002] Colored pencil leads are a type of pencil lead that uses pigments as colorants and are widely popular in artistic creation. Colored pencil leads mainly use clay as a binder, and are prepared through processes such as mixing and grinding, extrusion molding, and drying after adding pigments, water, adhesives, oils, and waxes.

[0003] Traditional colored pencil leads are prone to getting sticky hands. All the materials used are industrial grade, and there may be problems such as excessive heavy metals, which is not good for the health of users. After the used colored cores are discarded, they also pollute the environment. Moreover, when in use, due to the uneven mixing of raw materials, phenomena such as uneven color and paper scratching may occur.

[0004] Currently, the application of fruit and vegetable powders in industry has poor color display effects. According to the normal production process of pencil leads, when using fruit and vegetable powders as colorants, after heating during processing, the fruit and vegetable powders will change color, and the coloring effect is very poor, urgently needing improvement. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a non-toxic, harmless, green and environmentally friendly colored pencil lead;

[0006] Another purpose of the present invention is to provide a method for preparing the non-toxic, harmless, green and environmentally friendly colored pencil lead;

[0007] The above purposes of the present invention are achieved through the following technical solutions:

[0008] The present invention first provides a non-toxic and harmless colored pencil lead, which is made of the following components: fruit and vegetable powder, food-grade titanium dioxide, polylactic acid (PLA), adipic acid butanediol ester and terephthalic acid butanediol ester copolymer (PBAT), and food-grade talc powder.

[0009] Preferably, the mass parts of each component are: 10 - 20 parts of fruit and vegetable powder, 8 - 20 parts of food-grade titanium dioxide, 18 - 30 parts of polylactic acid, 18 - 40 parts of adipic acid butanediol ester and terephthalic acid butanediol ester copolymer, and 28 - 40 parts of food-grade talc powder.

[0010] More preferably, the mass parts of each component are: 8 - 10 parts of fruit and vegetable powder, 8 - 10 parts of food-grade titanium dioxide, 18 - 20 parts of polylactic acid, 20 - 24 parts of adipic acid butanediol ester and terephthalic acid butanediol ester copolymer, and 40 - 42 parts of food-grade talc powder.

[0011] Most preferably, the mass parts of each component are: 10 parts of fruit and vegetable powder, 8 parts of food-grade titanium dioxide, 18 parts of polylactic acid, 24 parts of copolymer of butylene adipate and butylene terephthalate, and 40 parts of food-grade talc powder.

[0012] The fruit and vegetable powder described in the present invention can be carrot powder, purple sweet potato powder or spinach powder. These fruit and vegetable powders can be obtained by purchasing from a food factory, or can be prepared according to the conventional preparation methods in the food processing field (for example, after washing and drying the fruits and vegetables, they can be crushed into fine powder), and all can be applied to the present invention.

[0013] Another aspect of the present invention is to provide a method for preparing the non-toxic and harmless colored pencil cores, including:

[0014] (1) Dispersing and mixing the fruit and vegetable powder with polylactic acid and the copolymer of butylene adipate and butylene terephthalate evenly to obtain a mixture;

[0015] (2) Granulating the mixture to obtain granulated materials;

[0016] (3) Mixing and stirring the granulated materials obtained in step (2) with food-grade titanium dioxide and food-grade talc powder evenly and then granulating to obtain granulated materials; straightening and cooling the granulated materials to obtain the product.

[0017] As a preferred specific implementation manner of the present invention, in step (1), the fruit and vegetable powder is dispersed and mixed evenly with polylactic acid and the copolymer of butylene adipate and butylene terephthalate by a high-speed disperser at 10,000 revolutions per minute.

[0018] As a preferred specific implementation manner of the present invention, in step (2), the mixture is added to a twin-screw extruder and mixed and stirred evenly and then extruded and granulated to obtain granulated materials.

[0019] As a preferred specific implementation manner of the present invention, in step (3), the granulated materials obtained in step (2) are mixed and stirred evenly with food-grade titanium dioxide and food-grade talc powder and then extruded and granulated in a twin-screw extruder to obtain granulated materials.

[0020] As a preferred specific implementation manner of the present invention, the parameters for extrusion granulation in the twin-screw extruder in step (2) or step (3) are preferably: setting the feeding speed at 8 - 9, the main machine speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the speed at 200 - 230 r / min.

[0021] The color rendering effect of single fruit and vegetable powder is not good and it is not suitable for use as a colorant. The present invention utilizes the good light resistance and heat resistance of polylactic acid, which is mutually fused with the fruit and vegetable powder and stirred at high temperature, so that the polylactic acid wraps the fruit and vegetable powder to form a color paste film. The colored pencil cores prepared with polylactic acid as an adhesive are very brittle and easy to break. Therefore, the present invention also adds a copolymer of butylene adipate and butylene terephthalate to increase the strength and is more conducive to forming a color paste film. It can not only make the fruit and vegetable powder show color, but also be more resistant to high temperature, biodegradable, more environmentally friendly, with diverse colors, more suitable for the children's market, and the cost is controllable.

[0022] When the present invention mixes the fruit and vegetable powder with polylactic acid and a copolymer of butylene adipate and butylene terephthalate to form a color paste film, a high-speed disperser is used to disperse the mixed powder of the fruit and vegetable powder, polylactic acid, and the copolymer of butylene adipate and butylene terephthalate, breaking the intermolecular force, making the material disperse more evenly, improving the dispersion effect of the material, not easy to agglomerate and cake, and the use feel is delicate and smooth. The present invention uses a twin-screw extruder to extrude and granulate instead of the traditional core pressing process, with higher efficiency and better stability. Description of the Drawings

[0023] Figure 1 It is a scanning electron micrograph of the material; (A) is the scanning electron micrograph of the material not dispersed by a high-speed disperser at 10,000 revolutions, and (B) is the scanning electron micrograph of the material after being dispersed by a high-speed disperser at 10,000 revolutions. Detailed Embodiments

[0024] The following further describes the present invention in combination with specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and forms of the present invention without departing from the spirit and scope of the present invention, but these modifications and substitutions all fall within the protection scope of the present invention.

[0025] Example 1 Preparation of a non-toxic and harmless colored pencil core

[0026] (1) Prepare each component according to the following mass parts: 10 parts of carrot powder, 8 parts of food-grade titanium dioxide, 18 parts of polylactic acid, 24 parts of a copolymer of butylene adipate and butylene terephthalate, and 40 parts of food-grade talc powder;

[0027] (2) Disperse and mix the carrot powder, polylactic acid, and the copolymer of butylene adipate and butylene terephthalate evenly in a high-speed disperser at 10,000 revolutions to obtain a mixture;

[0028] (3) Add the mixture to a twin-screw extruder, mix and stir evenly, and then extrude and pelletize to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min;

[0029] (4) Mix the pellets obtained in step (3) with food-grade titanium dioxide and food-grade talcum powder, stir evenly, and then extrude and pelletize in a twin-screw extruder to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min; Straighten and cool the obtained pellets to obtain the product.

[0030] Preparation of non-toxic and harmless colored pencil leads in Example 2

[0031] (1) Prepare the following components according to the mass parts: 10 parts of carrot powder, 8 parts of food-grade titanium dioxide, 18 parts of polylactic acid, 18 parts of adipic acid butanediol ester and terephthalic acid butanediol ester copolymer, and 28 parts of food-grade talcum powder;

[0032] (2) Disperse and mix the carrot powder with polylactic acid and adipic acid butanediol ester and terephthalic acid butanediol ester copolymer evenly in a high-speed disperser at ten thousand revolutions to obtain a mixture;

[0033] (3) Add the mixture to a twin-screw extruder, mix and stir evenly, and then extrude and pelletize to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min;

[0034] (4) Mix the pellets obtained in step (3) with food-grade titanium dioxide and food-grade talcum powder, stir evenly, and then extrude and pelletize in a twin-screw extruder to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min; Straighten and cool the obtained pellets to obtain the product.

[0035] Preparation of non-toxic and harmless colored pencil leads in Example 3

[0036] (1) Prepare the following components according to the mass parts: 20 parts of carrot powder, 20 parts of food-grade titanium dioxide, 30 parts of polylactic acid, 40 parts of adipic acid butanediol ester and terephthalic acid butanediol ester copolymer, and 40 parts of food-grade talcum powder;

[0037] (2) Disperse and mix the carrot powder with polylactic acid and adipic acid butanediol ester and terephthalic acid butanediol ester copolymer evenly in a high-speed disperser at ten thousand revolutions to obtain a mixture;

[0038] (3) Add the mixture into a twin-screw extruder, mix and stir evenly, and then extrude and pelletize to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min;

[0039] (4) Mix the pellets obtained in step (3) with food-grade titanium dioxide and food-grade talcum powder, stir evenly, and then extrude and pelletize in a twin-screw extruder to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min. Straighten and cool the obtained pellets to obtain the product.

[0040] Preparation of Non-toxic and Harmless Colored Pencil Leads in Example 4

[0041] (1) Prepare each component according to the following mass parts: 10 parts of carrot powder, 8 parts of food-grade titanium dioxide, 20 parts of polylactic acid, 24 parts of copolymer of butylene adipate and butylene terephthalate, and 42 parts of food-grade talcum powder;

[0042] (2) Disperse and mix the carrot powder with polylactic acid and copolymer of butylene adipate and butylene terephthalate evenly in a high-speed disperser at 10,000 revolutions per minute to obtain a mixture;

[0043] (3) Add the mixture into a twin-screw extruder, mix and stir evenly, and then extrude and pelletize to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min;

[0044] (4) Mix the pellets obtained in step (3) with food-grade titanium dioxide and food-grade talcum powder, stir evenly, and then extrude and pelletize in a twin-screw extruder to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine rotation speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the rotation speed at 200 - 230 r / min. Straighten and cool the obtained pellets to obtain the product.

[0045] Preparation of Non-toxic and Harmless Colored Pencil Leads in Example 5

[0046] (1) Prepare each component according to the following mass parts: 8 parts of carrot powder, 12 parts of food-grade titanium dioxide, 24 parts of polylactic acid, 28 parts of copolymer of butylene adipate and butylene terephthalate, and 32 parts of food-grade talcum powder;

[0047] (2) Disperse and mix the carrot powder, polylactic acid, and the copolymer of butylene adipate and butylene terephthalate evenly in a high-speed disperser at 10,000 revolutions per minute to obtain a mixture.

[0048] (3) Add the mixture to a twin-screw extruder, mix and stir evenly, and then extrude and pelletize to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the speed at 200 - 230 r / min.

[0049] (4) Mix and stir evenly the pellets obtained in step (3) with food-grade titanium dioxide and food-grade talc powder, and then extrude and pelletize in a twin-screw extruder to obtain pellets. The pelletizing parameters are as follows: set the feeding speed at 8 - 9, the main machine speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the speed at 200 - 230 r / min. Straighten and cool the obtained pellets to get the product.

[0050] Experimental Example 1 Screening Test on the Color Development of Different Adhesives for Fruit and Vegetable Powders

[0051] The color development effect of fruit and vegetable powders in industrial applications is not good. According to the normal production process of pencil leads, using fruit and vegetable powders as colorants, after heating during processing, the fruit and vegetable powders will change color, and the coloring effect is very poor. Therefore, the color development effect of single fruit and vegetable powders is not good and is not suitable for use as colorants. To improve the color development effect of fruit and vegetable powders, the color development effects of different adhesives on fruit and vegetable powders were compared. The specific experimental scheme and experimental results are shown in Table 1.

[0052] Table 1 Experimental Results of Different Adhesive Types on the Color Development of Fruit and Vegetable Powders

[0053]

[0054] Note: PVC (polyvinyl chloride); PMMA (polymethyl methacrylate).

[0055] In this experiment, the common adhesives for colored pencil leads (such as gum arabic, CMC, xanthan gum, sodium alginate, and edible gelatin, etc.) were compared. It was found that using ordinary common adhesives with fruit and vegetable powders as colorants could not make the fruit and vegetable powders develop color. However, using adhesives made of high-molecular materials, such as PLA, PVC, or PMMA, etc., could make the fruit and vegetable powders develop color. But after comparing with other common high-molecular materials, it was found that using PLA had the best color development effect on fruit and vegetable powders. However, during the experiment, it was found that the colored pencil leads made of PLA were very brittle and easy to break. Therefore, a certain amount of PBAT was added to increase the strength of the colored pencil leads.

[0056] Experimental Example 2 Scanning Electron Microscope Observation of Materials after Different Dispersing Methods

[0057] The carrot powder, polylactic acid, and the copolymer of butylene adipate and butylene terephthalate were dispersed and mixed evenly by a high-speed disperser at 10,000 revolutions per minute. After dispersion, it was observed under a scanning electron microscope. At the same time, the fruit and vegetable powder, polylactic acid, and the copolymer of butylene adipate and butylene terephthalate were dispersed and stirred conventionally and mixed evenly, and then observed under a scanning electron microscope.

[0058] It was found by observing under a scanning electron microscope ( Figure 1 ), for the material body dispersed by the high-speed disperser at 10,000 revolutions per minute, due to the increase in the temperature inside the cylinder and the high-speed rotation of the cutter wheel, not only can the particle size of the material be made smaller, but also the intermolecular force can be destroyed, making the material body more evenly dispersed, with basically no large agglomeration and wrapping phenomenon, and making the raw materials more evenly mixed.

[0059] Test Example 3: Test on the influence of components with different ratios on the color rendering and hand feeling effects of pencil leads

[0060] First, the fruit and vegetable powder, PLA, and PBAT were mixed in different proportions (Table 2) to form a color paste film, which was used as an adhesive and pigment in subsequent tests.

[0061] Table 2 Mixing carrot powder, PLA, and PBAT in different proportions to form a color paste film

[0062]

[0063] The color paste films obtained by mixing carrot powder, PLA, and PBAT in different proportions were combined with food-grade titanium dioxide and food-grade talc powder prepared in different proportions to prepare pencil leads, and their color rendering and hand feeling effects were respectively investigated. The specific combination proportions, color rendering, and hand feeling effects are shown in Tables 3 - 6. The performance measurement results of the colored pencil leads prepared by different schemes are shown in Tables 7 and 8.

[0064] Table 3 Color rendering and hand feeling effects of different color paste films mixed with food-grade titanium dioxide and talc powder in different proportions

[0065]

[0066]

[0067] Table 4 Color rendering and hand feeling effects of different color paste films mixed with food-grade titanium dioxide and talc powder in different proportions

[0068] Solution 7 Solution 8 Solution 9 Solution 10 Solution 11 Solution 12 Color paste film Color paste film 3 Color paste film 3 Color paste film 3 Color paste film 4 Color paste film 4 Color paste film 4 Food-grade titanium dioxide 8 12 20 8 12 20 Food-grade talc 40 36 28 40 36 28 Color development ★★★★ ★★★ ★★★ ★★★★ ★★★★ ★★★ Hand feeling ★★★★ ★★★★ ★★★ ★★★★★ ★★★★ ★★★★

[0069] Table 5 Color rendering and hand feeling effects of different color paste films mixed with food-grade titanium dioxide and talc powder in different proportions

[0070] Solution 13 Solution 14 Solution 15 Solution 16 Solution 17 Solution 18 Color paste film Color paste film 5 Color paste film 5 Color paste film 5 Color paste film 6 Color paste film 6 Color paste film 6 Food-grade titanium dioxide 8 12 20 8 12 20 Food-grade talc 40 36 28 40 36 28 Color development ★★★★★ ★★★★ ★★★ ★★★★ ★★★★ ★★★★ Hand feeling ★★★★ ★★★ ★★★ ★★★★ ★★★ ★★

[0071] Table 6 Color display and feel effects of different color paste films mixed with different ratios of food-grade titanium dioxide and talc powder

[0072] Solution 19 Solution 20 Solution 21 Color paste film Color paste film 7 Color paste film 7 Color paste film 7 Food-grade titanium dioxide 8 12 20 Food-grade talc 40 36 28 Color development ★★★★ ★★★★ ★★★★ Hand feeling ★★★★ ★★★ ★★★

[0073] Note: For color display, feel, and strength, 5 stars represent very good, and below 5 stars represents a gradual decrease.

[0074] Table 7 Performance determination of colored pencil leads prepared by different schemes

[0075]

[0076]

[0077] Table 8 Performance determination of colored pencil leads prepared by different schemes

[0078]

[0079] According to the national standard GB / T 26704, the measured indicators should meet the national standards. Based on the tests of feel and color display, as well as the comparison of the stability of each scheme, the ratio of Scheme 4 has the best effect on color display, feel, and other performance of the pencil lead.

Claims

1. A colored pencil lead, characterized in that, it is made of the following components: fruit and vegetable powder, food-grade titanium dioxide, polylactic acid, copolymer of butylene adipate and butylene terephthalate, and food-grade talc powder; the mass parts of each component are: 10 parts of fruit and vegetable powder, 8 parts of food-grade titanium dioxide, 18 parts of polylactic acid, 24 parts of copolymer of butylene adipate and butylene terephthalate, and 40 parts of food-grade talc powder; Its preparation method includes: (1) dispersing and mixing evenly the fruit and vegetable powder with polylactic acid and copolymer of butylene adipate and butylene terephthalate to obtain a mixture; (2) granulating the mixture to obtain pellets; (3) mixing and stirring evenly the pellets obtained in step (2) with food-grade titanium dioxide and food-grade talc powder and granulating to obtain pellets; straightening the pellets, cooling, and then obtaining the product.

2. The colored pencil lead according to claim 1, characterized in that, the fruit and vegetable powder includes a mixture composed of one or more of carrot powder, purple sweet potato powder or spinach powder in any proportion.

3. The colored pencil lead according to claim 1, characterized in that, in step (1), the fruit and vegetable powder is dispersed and mixed evenly with polylactic acid and copolymer of butylene adipate and butylene terephthalate by a high-speed disperser at 10,000 revolutions per minute.

4. The colored pencil lead according to claim 1, characterized in that, in step (2), the mixture is added to a twin-screw extruder, mixed and stirred evenly, and extruded and granulated to obtain pellets.

5. The colored pencil lead according to claim 1, characterized in that, in step (3), the pellets obtained in step (2) are mixed and stirred evenly with food-grade titanium dioxide and food-grade talc powder, and extruded and granulated in a twin-screw extruder to obtain pellets.

6. The colored pencil lead according to claim 1, characterized in that, the parameters for extrusion granulation in step (2) or step (3) in the twin-screw extruder are: set the feeding speed at 8 - 9, the main machine speed at 200 r / min, the head temperature at 250 °C, the barrel temperature at 230 °C, and the speed at 200 - 230 r / min.

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