Mildew-proof and dirt-proof pen refill and pencil

Abstract

The invention belongs to the field of stationery, and particularly relates to a mould-proof and dirt-proof pen refill and a pencil. According to the mould-proof and dirt-proof pen refill provided by the invention, the formula and the melt extrusion process of the pen refill are optimized, and an environment-friendly material, namely the bio-based resin polylactic acid, is adopted as a raw material, so that a continuous film can be formed when the pen refill is used for writing on paper, and the pen refill can be cleaned and dirt can be prevented while being finally easily erased by an eraser. The invention provides a pencil comprising the refill, and the pencil can prevent mildew and dirty hands.

Description

Technical Field

[0001] This invention belongs to the field of stationery, specifically a mildew-proof and dirt-proof pen lead and pencil. Background Technology

[0002] Traditional colored pencil leads are made from a blend of various chemical components, including pigments, dyes, oils, waxes, fillers, and binders. These materials are prone to mold growth in humid environments. In recent years, resin pencil leads have seen increasing demand in both domestic and international markets due to their smooth writing and stain-resistant properties. Their synthetic polymers lack the nutrient base for mold growth, thus providing excellent mold resistance.

[0003] Chinese patent application CN201310268556.4 discloses a polymer material pen lead and pencil, comprising the following raw material components by weight percentage: 30%–70% thermoplastic plastic, 27%–67% filler, 1%–2% compatibilizer, and 2%–8% toughening agent. It is mainly composed of thermoplastic plastic and inorganic filler, giving the pen lead clean, stain-resistant, and mildew-resistant properties. However, the thermoplastic plastic is difficult to degrade and is not environmentally friendly, and its erasing performance is poor. Summary of the Invention

[0004] The present invention aims to overcome the aforementioned problems of polymer material pen leads in the prior art and provides a mold-proof and dirt-proof pen lead and pencil. By optimizing the pen lead formula and melt extrusion process, and using environmentally friendly bio-based resin polylactic acid as raw material, the pen lead can form a continuous film when writing on paper, ensuring that it is easy to erase with an eraser while being clean and dirt-proof.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a mold-resistant and stain-resistant pen refill, wherein the components of the mold-resistant and stain-resistant pen refill, by weight parts, include:

[0007] 40-50 parts polylactic acid resin;

[0008] 10-15 parts polycaprolactone;

[0009] 3-5 parts compatibilizer;

[0010] 5-10 parts lubricant;

[0011] 2-5 parts of surface-treated zinc oxide;

[0012] 10 to 20 parts pigment.

[0013] This invention optimizes the pen refill formula, using biodegradable bio-based resin polylactic acid as the raw material and polycaprolactone as the toughening agent. The resulting material, when blended with paper, forms a continuous, thin film with weak adhesion to the paper. This film is relatively strong; its structure cannot be damaged by rubbing it with the hand, but the mechanical energy generated when rubbed with an eraser can roll the entire film off the paper, thus achieving clean erasure.

[0014] Preferably, the polylactic acid resin is injection molding grade PLA.

[0015] Preferably, the mass ratio of polylactic acid resin to polycaprolactone is (3-5):1.

[0016] Polylactic acid (PLA) resin, as a rigid matrix, provides the necessary hardness, strength, and moldability for the pen refill. Polycaprolactone (PCL), with its good flexibility, is distributed as a dispersed phase within the PLA resin, improving the writing feel and erasability of the pen refill. Based on experimental and theoretical research, our team discovered that a mass ratio of PLA resin to PCL of (2–4):1 allows PCL to provide flexibility and lubricity without compromising the overall rigidity of the pen refill.

[0017] Preferably, the compatibilizer is a maleic anhydride grafted compatibilizer.

[0018] Maleic anhydride grafted polymer compatibilizers can enhance the interfacial bonding between polylactic acid and polycaprolactone, allowing polycaprolactone to be evenly distributed in polylactic acid resin. This provides excellent toughness and lubricity without affecting the overall rigidity.

[0019] Preferably, the lubricant is calcium stearate.

[0020] Calcium stearate acts as a lubricant to aid internal lubrication, further adjusting hardness and promoting erasure.

[0021] Preferably, the method for preparing the surface-treated zinc oxide includes the following steps: dispersing zinc oxide in a solution, adding a silane coupling agent to react, and drying.

[0022] After surface pretreatment, it can be ensured that zinc oxide is stably and uniformly dispersed in polylactic acid resin during melt blending, thereby ensuring that the anti-mildew performance of the pen refill is long-lasting and efficient.

[0023] Furthermore, the silane coupling agent is KH-550.

[0024] Preferably, the preparation method of the anti-mildew and anti-stain pen refill includes the following steps: the components of the pen refill are mixed evenly and kneaded, mixed and granulated by a mixer and an extruder, and then shaped and cut into appropriate lengths by an extrusion molding machine to obtain the anti-mildew and anti-stain pen refill.

[0025] Furthermore, the preparation method specifically includes the following steps:

[0026] (S1) Mix polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide in a high-speed mixer at 30-90°C until homogeneous, then add pigment and mix until homogeneous.

[0027] (S2) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 5 to 25 minutes and the extrusion temperature is 150 to 170°C.

[0028] (S3) Prepare and cut resin pencil leads into suitable lengths using a single-screw or conical twin-screw extruder, with an extrusion temperature of 160-175℃.

[0029] In a second aspect, the present invention provides a pencil, including the aforementioned lead and a pencil cap for enclosing the lead.

[0030] The present invention has the following beneficial effects:

[0031] (1) This invention provides a mildew-proof and dirt-proof pen refill. By optimizing the pen refill formula and melt extrusion process, and using environmentally friendly bio-based resin polylactic acid as raw material, the pen refill can form a continuous film when writing on paper, ensuring that it is easy to be erased by an eraser while being clean and dirt-proof.

[0032] (2) The present invention provides a pencil including the above-mentioned lead, which can prevent mold and dirt from getting on the hands. Detailed Implementation

[0033] General Implementation Examples

[0034] A mildew-proof and stain-resistant pen refill, wherein the components of the mildew-proof and stain-resistant pen refill, by weight parts, include:

[0035] 40-50 parts polylactic acid resin;

[0036] 10-15 parts polycaprolactone;

[0037] 3-5 parts compatibilizer;

[0038] 5-10 parts lubricant;

[0039] 2-5 parts of surface-treated zinc oxide;

[0040] 10 to 20 parts pigment.

[0041] Preferably, the polylactic acid resin is injection molding grade PLA.

[0042] Preferably, the mass ratio of polylactic acid resin to polycaprolactone is (3-5):1.

[0043] Preferably, the compatibilizer is a maleic anhydride grafted compatibilizer.

[0044] Preferably, the lubricant is calcium stearate.

[0045] Preferably, the method for preparing the surface-treated zinc oxide includes the following steps: dispersing zinc oxide in a solution, adding a silane coupling agent to react, and drying.

[0046] Furthermore, the silane coupling agent is KH-550.

[0047] Preferably, the preparation method of the anti-mildew and anti-stain pen refill includes the following steps: the components of the pen refill are mixed evenly and kneaded, mixed and granulated by a mixer and an extruder, and then shaped and cut into appropriate lengths by an extrusion molding machine to obtain the anti-mildew and anti-stain pen refill.

[0048] Furthermore, the preparation method specifically includes the following steps:

[0049] (S1) Mix polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide in a high-speed mixer at 30-90°C until homogeneous, then add pigment and mix until homogeneous.

[0050] (S2) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 5 to 25 minutes and the extrusion temperature is 150 to 170°C.

[0051] (S3) Prepare and cut resin pencil leads into suitable lengths using a single-screw or conical twin-screw extruder, with an extrusion temperature of 160-175℃.

[0052] A pencil includes the aforementioned lead and a pencil cap for enclosing the lead.

[0053] Example 1

[0054] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0055] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0056] (2) As shown in Table 1, polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 30°C, and then pigment is added and mixed evenly; the polylactic acid resin is injection molding grade PLA; the compatibilizer is maleic anhydride grafted compatibilizer; and the lubricant is calcium stearate.

[0057] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 15 minutes and the extrusion temperature is 170℃.

[0058] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into suitable lengths, with an extrusion temperature of 160-175℃.

[0059] The resulting pencil lead achieves the writing effect of an HB pencil, with a Noordino hardness comparable to a 2H pencil, and is flexible and resilient. Rubbing it by hand leaves no filler residue, keeping hands clean. Erasing with an eraser results in a clean, rolled-up eraser that rises cleanly from the paper.

[0060] Example 2

[0061] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0062] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0063] (2) As shown in Table 1, the polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 60°C, and then the pigment is added and mixed evenly.

[0064] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 20 minutes and the extrusion temperature is 170℃.

[0065] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into suitable lengths, with an extrusion temperature of 175°C.

[0066] The resulting pencil lead achieves the writing effect of an F-class pencil in terms of color, and has the Knoop hardness of an HB-class pencil, while also being flexible and resilient. When rubbed by hand, it does not stick to any filler, keeping hands clean. When erased with an eraser, the ink rolls up cleanly from the paper.

[0067] Example 3

[0068] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0069] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0070] (2) As shown in Table 1, the polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 90°C, and then the pigment is added and mixed evenly.

[0071] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 25 minutes and the extrusion temperature is 150℃.

[0072] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into appropriate lengths, with an extrusion temperature of 165°C.

[0073] The resulting pencil lead achieves the writing effect of an H-class pencil in terms of color and Knoop hardness, while also being flexible and resilient. Rubbing it with your hand leaves no filler residue, keeping your hands clean. Erasing with an eraser results in a clean, rolled-up eraser that rises cleanly from the paper.

[0074] Example 4

[0075] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0076] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0077] (2) As shown in Table 1, the polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 30°C, and then the pigment is added and mixed evenly.

[0078] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 5 minutes and the extrusion temperature is 170℃.

[0079] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into suitable lengths, with an extrusion temperature of 175°C.

[0080] The resulting pencil lead achieves the writing effect of an HB pencil, with a Noordino hardness comparable to a 2H pencil, and is flexible and resilient. Rubbing it by hand leaves no filler residue, keeping hands clean. Erasing with an eraser results in a clean, rolled-up eraser that rises cleanly from the paper.

[0081] Example 5

[0082] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0083] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0084] (2) As shown in Table 1, the polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 30°C, and then the pigment is added and mixed evenly.

[0085] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 25 minutes and the extrusion temperature is 170℃.

[0086] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into suitable lengths, with an extrusion temperature of 160°C.

[0087] The resulting pencil lead achieves the writing effect of an F-class pencil in terms of color, and has a Noordino hardness equivalent to a 2H-class pencil. It is also flexible and resilient. Rubbing it with your hand leaves no residue, keeping your hands clean. Erasing with an eraser removes the ink cleanly by the ink rolling off the entire sheet of paper.

[0088] Example 6

[0089] A mold-proof and stain-resistant pen refill, the preparation method includes the following steps:

[0090] (1) Disperse zinc oxide in a solution, add silane coupling agent KH-550 to react, and dry;

[0091] (2) As shown in Table 1, the polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 30°C, and then the pigment is added and mixed evenly.

[0092] (3) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 25 minutes and the extrusion temperature is 170℃.

[0093] (4) Use a single-screw or conical twin-screw extruder to prepare and cut resin pencil leads into suitable lengths, with an extrusion temperature of 175°C.

[0094] The resulting pencil lead achieves the writing effect of an H-class pencil in terms of color, and has the Knoop hardness of an F-class pencil. It is also flexible and resilient. Rubbing it with your hand leaves no residue, keeping your hands clean. Erasing with an eraser removes the ink cleanly by the ink rolling off the entire sheet of paper.

[0095] Example 7

[0096] Example 7 provides a pen refill similar to that of Example 6, except that the mass ratio of polylactic acid resin to polycaprolactone in Example 7 is less than 3:1.

[0097] The resulting pencil lead achieves the writing effect of an H-class pencil in terms of color, and the Noordino hardness of an F-class pencil, while also being flexible and resilient. When rubbed by hand, the ink curls up completely from the paper. Erasing with an eraser also results in a clean, curled-up ink mark. This is presumably due to the high polycaprolactone content, which increases the lead's lubricity and makes it less prone to adhering to the paper.

[0098] Example 8

[0099] Example 8 provides a pen refill similar to that of Example 5, except that the mass ratio of polylactic acid resin to polycaprolactone in Example 8 is greater than 5:1.

[0100] The resulting pencil lead achieves the writing effect of an H-class pencil in terms of color intensity, and has a Nourish hardness comparable to a 2H-class pencil. It is also flexible and resilient. Rubbing it by hand leaves no residue or filler residue, even with clean hands. Erasing with an eraser leaves mottled marks and residue. This is presumably because the high polylactic acid resin content reduces the lead's lubricity, causing the ink to rub against the paper in a grainy manner instead of forming a thin film, making it difficult to erase.

[0101] Polylactic acid resin Polycaprolactone compatibilizer lubricant Surface-treated zinc oxide pigment Example 1 47 10 3 10 5 10 Example 2 50 15 3 5 2 10 Example 3 40 10 5 7 3 20 Example 4 50 10 3 10 2 10 Example 5 50 10 3 10 2 10 Example 6 45 15 3 10 2 10 Example 7 30 15 5 10 5 20 Example 8 55 10 3 5 2 10 Comparative Example 1 47 10 3 10 5 10

[0102] Comparative Example 1

[0103] Comparative Example 1 provides a pen refill similar to that of Example 1, except that the zinc oxide in Comparative Example 1 was not surface-treated with a silane coupling agent.

[0104] The resulting pencil lead achieves the writing effect of an H-class pencil in terms of color, and has a Noordino hardness equivalent to a 2H-class pencil. It is also flexible and resilient. Rubbing it with your hand leaves no residue, keeping your hands clean. Erasing with an eraser results in a clean, rolled-up eraser that rises cleanly from the paper.

[0105] Test case

[0106] This test example conducts anti-mold tests on the pen refills provided in Examples 1-8 and Comparative Examples 1-4 to test their anti-mold performance. The anti-mold test environment is: humidity >90%RH, temperature 30℃, and time 28 days.

[0107] The test results obtained in this test example show that Examples 1-8 achieved a mold resistance level of 0 against six mixed molds, including Aspergillus niger, Aspergillus terreus, Penicillium, Penicillium cordiformis, budding short-stemmed mold, and Chaetomium globosum. This indicates that under the mold test environment, no mold grew on the surface of the mold-resistant and dirt-resistant pen refill. The surface of the pen refill in Comparative Example 1 was mottled. The reason is presumably that the zinc oxide in Comparative Example 1 was not treated with a silane coupling agent. The zinc oxide anti-mold agent clumped together in the polylactic acid resin, resulting in poor dispersibility and inadequate anti-mold performance.

[0108] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A mildew-proof and stain-resistant pen refill, characterized in that, The components of the anti-mildew and anti-stain pen refill, by weight, include: 40-50 parts of polylactic acid resin; 10-15 parts polycaprolactone; 3-5 parts compatibilizer; 5-10 parts lubricant; 2-5 parts of surface-treated zinc oxide; 10 to 20 parts pigment.

2. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The polylactic acid resin is injection molding grade PLA.

3. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The mass ratio of polylactic acid resin to polycaprolactone is (3-5):

1.

4. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The compatibilizer is a maleic anhydride grafted compatibilizer.

5. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The lubricant is calcium stearate.

6. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The method for preparing the surface-treated zinc oxide includes the following steps: dispersing zinc oxide in a solution, adding a silane coupling agent to react, and drying.

7. The anti-mildew and anti-stain pen refill according to claim 6, characterized in that, The silane coupling agent is KH-550.

8. The anti-mildew and anti-stain pen refill according to claim 1, characterized in that, The method for preparing the anti-mildew and anti-stain pen refill includes the following steps: mixing the components of the pen refill evenly and kneading, mixing and granulating them through a mixer and an extruder, then preparing and shaping them using an extrusion molding machine and cutting them into appropriate lengths to obtain the anti-mildew and anti-stain pen refill.

9. The anti-mildew and anti-stain pen refill according to claim 8, characterized in that, The preparation method specifically includes the following steps: (S1) Polylactic acid resin, polycaprolactone, compatibilizer, lubricant, and surface-treated zinc oxide are mixed evenly in a high-speed mixer at 30-90°C, and then pigment is added and mixed evenly. (S2) The material is kneaded and mixed in an internal mixer, and then granulated using a twin-screw extruder. The mixing time is 5 to 25 minutes and the extrusion temperature is 150 to 170°C. (S3) Prepare and cut resin pencil leads into suitable lengths using a single-screw or conical twin-screw extruder, with an extrusion temperature of 160-175℃.

10. A pencil, characterized in that, Includes the pencil lead as described in any one of claims 1 to 9 and a pencil cap for enclosing the pencil lead.