High eraser rate TPE eraser material and preparation method thereof

Abstract

The application discloses a high-erasability TPE eraser material and a preparation method thereof, and belongs to the technical field of stationery. Firstly, nano-silicon dioxide is modified by a silane coupling agent and grafted with MMA and BA monomers to prepare functionalized nano-silicon dioxide powder; meanwhile, phenol modified beta-pinene styrene resin is catalytically synthesized from phenol, beta-pinene and styrene as raw materials; finally, the resin is mixed with the functionalized nano-silicon dioxide powder, SEBS elastomer and antioxidants and lubricants, and then melt-extruded and granulated to obtain the TPE eraser material. The functionalized nano-filler with a surface grafted polymer is synergized with the phenol modified beta-pinene styrene resin with polarity and flexible segments to build a chemical-physical dual-enhanced interface between the filler and the rubber matrix, so that the technical problem that the traditional TPE eraser is difficult to simultaneously ensure high erasability and paper damage is effectively solved, and the application is suitable for stationery eraser products with strict requirements on wiping performance.

Description

Technical Field

[0001] This invention belongs to the field of stationery technology, specifically a high-erasability TPE eraser material and its preparation method. Background Technology

[0002] Erasers are essential stationery for daily writing and drawing. Their erasing effect, appearance, texture, and user experience directly affect user needs. Traditional erasers are mostly made of polyvinyl chloride (PVC) or natural rubber, which have problems such as non-recyclability, easy dust generation, hard feel, and easy aging. Thermoplastic elastomers (TPEs) have become the key development direction for environmentally friendly eraser materials due to their advantages such as recyclability, almost no dust generation, soft touch, and adjustable mechanical properties.

[0003] However, existing TPE-based eraser materials often face a difficult technical dilemma in improving erasing performance. To pursue high erasing rates, common techniques include introducing high-hardness resins (such as petroleum resins, C5 / C9 resins) or large amounts of inorganic fillers (such as calcium carbonate, talc) into the TPE matrix. While these methods can enhance erasing performance by increasing material hardness and the coefficient of friction, the high hardness and surface polarity of rigid resins significantly alter the tribological properties of the TPE matrix, resulting in a rough feel, increased resistance, and poor erasing smoothness during the erasing process. At the same time, the introduction of large amounts of fillers sacrifices the transparency and uniformity of the material, making the product look cheap. Furthermore, during the erasing process, the hard particles can easily cause scratches, especially when erasing fine papers such as high-grade sketch paper and watercolor paper, which can easily damage the paper fibers, causing fuzzing or tearing. Summary of the Invention

[0004] The purpose of this invention is to provide a high erasure rate TPE eraser material and its preparation method. By using functionalized nanofillers with surface-grafted polymers and phenol-modified β-pinene styrene resin with polar and flexible segments, a chemical-physical dual-reinforcement interface is constructed between the filler and the rubber matrix. This effectively solves the technical problem that traditional TPE erasers cannot achieve both high erasure rate and paper damage. It is suitable for stationery eraser products with strict requirements for erasure performance.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing a high erasure rate TPE eraser material includes the following steps: Step 1: Modify the nano-silica powder with silane coupling agent KH574, and graft MMA and BA monomers in situ to obtain functionalized nano-silica powder.

[0006] Step 2: Using phenol, β-pinene, and styrene as raw materials, phenol-modified β-pinene styrene resin is obtained under the action of a Lewis acid catalyst.

[0007] Step 3: Functionalized nano silica powder, phenol-modified β-pinene styrene resin, SEBS, antioxidant 1010, antioxidant 168, zinc stearate, paraffin oil and tributyl citrate are mixed, melt extruded and granulated to obtain high erasure rate TPE eraser material.

[0008] Furthermore, the mass ratio of phenol-modified β-pinene styrene resin, SEBS, antioxidant 1010, antioxidant 168, lubricant zinc stearate, functionalized nano silica powder, paraffin oil, and tributyl citrate is 50-60:22-28:0.2-0.4:0.2-0.4:0.4-0.6:10-14:15-21:5-7.

[0009] Furthermore, the melt extrusion temperature is 120-155℃, and the screw speed is 200-300 r / min.

[0010] Furthermore, the specific preparation steps of phenol-modified β-pinene styrene resin are as follows: The complex of methylcyclohexane and boron trifluoride diethyl ether was added to a reaction vessel and stirred at 250-350 rpm and -5-5℃ until homogeneous. The mixture was then added dropwise to the reaction vessel over 1 hour. After the addition was complete, the reaction was carried out at -2-2℃ for 3-5 hours. Phenol was then added to the vessel, and the reaction was continued for 0.8-1.2 hours under the same conditions. The reaction was stopped by adding excess hot water, and stirring was continued for 15-25 minutes. After the reaction solution cooled to room temperature, it was washed, separated from oil and water, and distilled under reduced pressure to obtain phenol-modified β-pinene styrene resin.

[0011] Furthermore, the mass ratio of methylcyclohexane, boron trifluoride diethyl ether complex, mixture and phenol is 90-100:6-7:82-100:7-8.5.

[0012] Furthermore, the mixture is composed of β-pinene and styrene in a mass ratio of 60-72:22-28.

[0013] Furthermore, the specific preparation steps of functionalized nano-silica powder are as follows: Under a nitrogen atmosphere, a mixture of methyl methacrylate, butyl acrylate, azobisisobutyronitrile, and methanol-water was added to a reaction vessel. Modified nano-silica powder was then added to the reaction vessel, and the reaction was carried out at 60-70℃ and 300-400 r / min for 10-14 h. After the reaction was completed, the product was collected, washed, and dried to obtain functionalized nano-silica powder.

[0014] Furthermore, the ratio of methyl methacrylate, butyl acrylate, azobisisobutyronitrile, methanol-water mixture and modified nano silica powder is 6-8g: 2-4g: 0.08-0.12g: 35-45mL: 4-6g.

[0015] Furthermore, the methanol-water mixed solution is prepared by mixing methanol and water in a volume ratio of 3:1.

[0016] Furthermore, the specific preparation steps of the modified nano-silica powder are as follows: Nano-silica and n-butanol were added to a reaction vessel and ultrasonically dispersed evenly. Then, glacial acetic acid was added to adjust the pH to 5. KH574 modifier was slowly added dropwise to the reaction vessel. The reaction was carried out at 300-500 r / min and 98-102℃ for 5-7 h. After the reaction was completed, the mixture was centrifuged, washed, dried, ground, and sieved to obtain modified nano-silica powder.

[0017] Furthermore, the ratio of nano-silica, n-butanol, and KH574 modifier is 4-6g: 45-55mL: 12-18g.

[0018] Furthermore, the KH574 modifier is obtained by mixing silane coupling agent KH574, deionized water and anhydrous ethanol in a mass ratio of 1.2-1.8:1.2-1.8:12-18.

[0019] The beneficial effects of this invention are: 1. This invention introduces functionalized nano-silica powder with surface-grafted polymers and phenol-modified β-pinene styrene resin, and blends them with thermoplastic elastomers and additives. This effectively solves the technical problem of traditional TPE erasers, which, in pursuit of high erasure rates, suffer from a rough feel and are prone to damaging fine paper due to the addition of high-hardness resins or large amounts of inorganic fillers. The resulting material maintains high erasure efficiency while having a soft feel due to its low surface hardness. Furthermore, the debris produced during erasing is in the form of fine strips, significantly reducing the risk of paper damage. It is especially suitable for stationery applications such as advanced sketching, watercolor painting, and precision drafting, where there are stringent requirements for erasure effect and paper protection.

[0020] 2. This invention modifies nano-silica with silane coupling agent KH574 and in-situ grafts MMA and BA monomers to obtain functionalized nano-silica powder. Reactive functional groups are introduced by condensing the silicon-oxygen bonds of the silane coupling agent with the hydroxyl groups on the surface of nano-silica. Then, polymer segments are grafted through in-situ free radical polymerization, which greatly improves the dispersibility and interfacial compatibility of the nanofiller in the organic matrix, effectively inhibits filler agglomeration, and avoids excessive increase in material hardness. At the same time, the microscopic protrusion structure of the nanoparticles can enhance the scratching and adsorption effect on pencil graphite, laying the foundation for improving the erasure rate.

[0021] 3. The phenol-modified β-pinene styrene resin synthesized from phenol, β-pinene, and styrene in this invention has both polar and flexible segments. It can be well blended with SEBS elastomers to reduce the overall surface hardness of the material, giving the eraser a soft feel and reducing the pressure on the paper during erasing. It can also form a stable interfacial bond with functionalized nanofillers and rubber matrix through its polar groups. At the same time, the swelling properties of the resin can enhance the adsorption and transfer capacity of pencil graphite, further optimizing the erasing effect. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A high erasure rate TPE eraser material, comprising the following steps: S1: Mix 1.5g of silane coupling agent KH574, 1.5g of deionized water and 15g of anhydrous ethanol to obtain KH574 modifier; add 5g of nano silica and 50mL of n-butanol to the reaction vessel, disperse evenly by ultrasonication, add glacial acetic acid to adjust the pH to 5, slowly add 15g of KH574 modifier to the reaction vessel, and react for 6h at a speed of 400r / min and a temperature of 100℃. After the reaction is completed, centrifuge to collect the precipitate, wash with anhydrous ethanol and dry at 70℃ for 8h, and finally grind and pass through a 200-mesh sieve to obtain modified nano silica powder.

[0024] A silane coupling agent modification method was adopted, using KH574 silane coupling agent and nano-silica as raw materials. The reaction was carried out under acidic heating and stirring conditions. The silicon-oxygen bonds of KH574 reacted with the hydroxyl groups on the surface of silica through a condensation reaction, introducing methacryloyloxy groups (reactive organic functional groups containing carbon-carbon double bonds) on the surface of silica, thereby obtaining surface-modified nano-silica powder, which improved its dispersibility and compatibility in the organic phase.

[0025] S2: Under a nitrogen atmosphere, 7g of methyl methacrylate (MMA), 3g of butyl acrylate (BA), 0.1g of initiator azobisisobutyronitrile (AIBN), and 40mL of methanol-water mixture (volume ratio 3:1) were added to a reactor. The mixture was stirred to fully dissolve the monomers and initiator. 5g of modified nano-silica powder was added to the reactor, and the reaction was carried out at 65℃ and 350r / min for 12h. After the reaction was completed, the product was collected and washed alternately with ethanol and ultrapure water to remove unreacted monomers and byproducts. The product was then vacuum dried at 90℃ to constant weight to obtain functionalized nano-silica powder.

[0026] In situ free radical polymerization was used to copolymerize the methacryloyloxy group on the surface of modified nano silica with methyl methacrylate (MMA) and butyl acrylate (BA) monomers under the action of an initiator, thereby introducing MMA-BA copolymer segments onto the surface of nano silica and obtaining functionalized nano silica powder.

[0027] S3: Mix 66.8g of β-pinene and 25.56g of styrene evenly to obtain a mixture; add 100g of methylcyclohexane and 6.5g of boron trifluoride diethyl ether complex to a reaction vessel and stir evenly at 300r / min and 0℃. Add 92g of the mixture dropwise to the reaction vessel over 1 hour. After the addition is complete, react for 4 hours at 0℃. Add 7.7g of phenol to the vessel and continue the reaction for 1 hour under the same conditions. Add excess hot water to stop the reaction and continue stirring for 20 minutes. After the reaction solution cools to room temperature, wash with water until the final wash solution is neutral. After oil-water separation and vacuum distillation, phenol-modified β-pinene styrene resin is obtained.

[0028] A cationic polymerization method was adopted, using boron trifluoride diethyl ether complex as Lewis acid catalyst, in a methylcyclohexane solvent system, to first copolymerize β-pinene with styrene, and then modify it with phenol for end-capping. After quenching termination, water washing to remove impurities, oil-water separation and vacuum distillation to remove devolatilization, phenol-modified β-pinene styrene resin was obtained.

[0029] S4: 55g of phenol-modified β-pinene styrene resin, 25g of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.3g of antioxidant 1010, 0.2g of antioxidant 168, 0.5g of lubricant zinc stearate, 12g of functionalized nano silica powder, 18g of paraffin oil, and 6g of tributyl citrate (TBC) are sequentially added to a high-speed mixer and mixed for 9 minutes at a speed of 900r / min and a temperature of 90℃ to ensure that SEBS fully absorbs the oil and the powder is evenly dispersed. The mixed material is fed into a twin-screw extruder and melt-blended and extruded at a temperature of 135℃ and a screw speed of 250r / min. After water cooling and pelletizing (particle size 2-3mm), a high-erasability TPE eraser material is obtained.

[0030] Example 2: A high erasure rate TPE eraser material, comprising the following steps: S1: Mix 1.2g of silane coupling agent KH574, 1.2g of deionized water and 12g of anhydrous ethanol to obtain KH574 modifier; add 4g of nano silica and 45mL of n-butanol to the reaction vessel, disperse evenly by ultrasonication, add glacial acetic acid to adjust the pH to 5, slowly add 12g of KH574 modifier to the reaction vessel, and react for 5h at a speed of 300r / min and a temperature of 98℃. After the reaction is completed, centrifuge to collect the precipitate, wash with anhydrous ethanol and dry at 70℃ for 8h, and finally grind and pass through a 200-mesh sieve to obtain modified nano silica powder.

[0031] S2: Under a nitrogen atmosphere, 6g of methyl methacrylate (MMA), 2g of butyl acrylate (BA), 0.08g of initiator azobisisobutyronitrile (AIBN), and 35mL of methanol-water mixture (volume ratio 3:1) were added to a reaction vessel. The mixture was stirred to fully dissolve the monomers and initiator. 4g of modified nano-silica powder was then added to the reaction vessel. The reaction was carried out at 60℃ and 300r / min for 10h. After the reaction was completed, the product was collected and washed alternately with ethanol and ultrapure water to remove unreacted monomers and byproducts. The product was then vacuum dried at 90℃ to constant weight to obtain functionalized nano-silica powder.

[0032] S3: Mix 60g of β-pinene and 22g of styrene evenly to obtain a mixture; add 90g of methylcyclohexane and 6g of boron trifluoride diethyl ether complex to a reaction vessel and stir evenly at a speed of 250r / min and a temperature of -5℃. Add 82g of the mixture dropwise to the reaction vessel over 1 hour. After the addition is complete, react for 3 hours at a temperature of -2℃. Add 7g of phenol to the vessel and continue the reaction for 0.8 hours under the same conditions. Add excess hot water to stop the reaction and continue stirring for 15 minutes. After the reaction solution cools to room temperature, wash with water until the final wash solution is neutral. After oil-water separation and vacuum distillation, phenol-modified β-pinene styrene resin is obtained.

[0033] S4: 50g of phenol-modified β-pinene styrene resin, 22g of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.2g of antioxidant 1010, 0.2g of antioxidant 168, 0.4g of lubricant zinc stearate, 10g of functionalized nano silica powder, 15g of paraffin oil, and 5g of tributyl citrate (TBC) are sequentially added to a high-speed mixer and mixed for 7 minutes at a speed of 800r / min and a temperature of 80℃ to ensure that SEBS fully absorbs the oil and the powder is evenly dispersed. The mixed material is fed into a twin-screw extruder and melt-blended and extruded at a temperature of 120℃ and a screw speed of 200r / min. After water cooling and pelletizing (particle size 2-3mm), a high-erasability TPE eraser material is obtained.

[0034] Example 3: A high erasure rate TPE eraser material, comprising the following steps: S1: Mix 1.8g of silane coupling agent KH574, 1.8g of deionized water and 18g of anhydrous ethanol to obtain KH574 modifier; add 6g of nano silica and 55mL of n-butanol to the reaction vessel, disperse evenly by ultrasonication, add glacial acetic acid to adjust the pH to 5, slowly add 18g of KH574 modifier to the reaction vessel, and react for 7h at a speed of 500r / min and a temperature of 102℃. After the reaction is completed, centrifuge to collect the precipitate, wash with anhydrous ethanol and dry at 70℃ for 8h, and finally grind and pass through a 200-mesh sieve to obtain modified nano silica powder.

[0035] S2: Under a nitrogen atmosphere, 8g of methyl methacrylate (MMA), 4g of butyl acrylate (BA), 0.12g of initiator azobisisobutyronitrile (AIBN), and 45mL of methanol-water mixture (volume ratio 3:1) were added to a reactor. The mixture was stirred to fully dissolve the monomers and initiator. 6g of modified nano-silica powder was then added to the reactor. The reaction was carried out at 70℃ and 400r / min for 14h. After the reaction was completed, the product was collected and washed alternately with ethanol and ultrapure water to remove unreacted monomers and byproducts. The product was then vacuum dried at 90℃ to constant weight to obtain functionalized nano-silica powder.

[0036] S3: Mix 72g of β-pinene and 28g of styrene evenly to obtain a mixture; add 100g of methylcyclohexane and 7g of boron trifluoride diethyl ether complex to a reaction vessel and stir evenly at a speed of 350r / min and a temperature of 5℃. Add 100g of the mixture dropwise to the reaction vessel over 1 hour. After the addition is complete, react for 5 hours at a temperature of 2℃. Add 8.5g of phenol to the vessel and continue the reaction for 1.2 hours under the same conditions. Add excess hot water to stop the reaction and continue stirring for 25 minutes. After the reaction solution cools to room temperature, wash with water until the final wash solution is neutral. After oil-water separation and vacuum distillation, phenol-modified β-pinene styrene resin is obtained.

[0037] S4: 60g of phenol-modified β-pinene styrene resin, 28g of styrene-ethylene-butene-styrene block copolymer (SEBS), 0.4g of antioxidant 1010, 0.4g of antioxidant 168, 0.6g of lubricant zinc stearate, 14g of functionalized nano silica powder, 21g of paraffin oil, and 7g of tributyl citrate (TBC) are sequentially added to a high-speed mixer and mixed for 11 minutes at a speed of 1000r / min and a temperature of 100℃ to ensure that SEBS fully absorbs the oil and the powder is evenly dispersed. The mixed material is fed into a twin-screw extruder and melt-blended and extruded at a temperature of 155℃ and a screw speed of 300r / min. After water cooling and pelletizing (particle size 2-3mm), a high-erasability TPE eraser material is obtained.

[0038] The raw materials used in Examples 1-3 of this application are all commercially available. Specifically, the silane coupling agent KH574 (99% purity) was purchased from Wuhan Jushun Chemical Co., Ltd.; methyl methacrylate (purity > 99.5%), butyl acrylate (reagent grade, 99%), β-pinene (98%), styrene (purity > 99.5%), methylcyclohexane (purity ≥ 99%), phenol (purity ≥ 99.5%), antioxidant 1010 (≥ 98%), and antioxidant 168 (98%) were also used. All were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; boron trifluoride diethyl ether complex (purity 99%) was purchased from Shandong Yinglang Chemical Co., Ltd.; styrene-ethylene-butene-styrene block copolymer (styrene content 28-31%, linear) was purchased from Dongguan Shenghao Plastic Raw Materials Co., Ltd.; nano silica (15nm, ≥99.5%), zinc stearate (Zn10-12%, 325 mesh), paraffin oil and tributyl citrate (≥98%) were purchased from Shanghai Aladdin Biochemical Co., Ltd.

[0039] Comparative Example 1: Based on Example 1, the modification and functionalization operations of nano-silica powder in steps S1 and S2 were omitted. In step S4, an equal amount of unmodified nano-silica powder was used directly, and all other steps and parameters remained unchanged to obtain TPE eraser material.

[0040] Comparative Example 2: Based on Example 1, the in-situ free radical polymerization grafting reaction in step S2 was omitted, and the modified nano silica powder obtained in step S1 was directly used in step S4. All other steps and parameters remained unchanged to obtain TPE eraser material.

[0041] Comparative Example 3: Based on Example 1, the preparation of phenol-modified β-pinene styrene resin in step S3 was omitted, and an equal amount of C9 petroleum resin was used directly to replace the phenol-modified β-pinene styrene resin in step S4. All other steps and parameters remained unchanged to obtain TPE eraser material.

[0042] The TPE eraser materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The surface hardness test was conducted in accordance with the ASTM D2240 standard. The surface hardness of each sample was measured using a Shore A hardness tester to evaluate the softness and hardness of the material under pressure. The lower the value, the softer the material is, the closer it is to natural rubber in feel, and the less pressure it puts on the paper when used.

[0043] The erasure rate test was conducted using the methods specified in the group standards T / CSSGA 1002-2017 "Erasers" and QB / T 2309-2010 "Erasers". The test quantifies the material's ability to erase standard pencil (HB) marks. The higher the value, the better the erasure efficiency and cleaning effect of the material.

[0044] The shape of the debris is qualitatively evaluated by visual observation after wiping, simulating the actual wiping process. This indicator can be used to indirectly assess the smoothness of the wiping process and the risk of paper damage: fine / strip-shaped debris usually indicates that the material has good plasticity during wiping, the debris is produced smoothly and there is little damage to the paper fiber structure; while coarse / strip-shaped or fragmented debris indicates that the wiping resistance is large and it is easy to cause paper fiber fuzzing or even breakage.

[0045] The results are shown in Table 1: Table 1 Performance test results of various TPE eraser materials

[0046] As shown in Table 1, the TPE eraser materials prepared in Examples 1-3 of this invention exhibit excellent comprehensive performance in three key aspects: surface hardness, erasure rate, and debris morphology. By introducing phenol-modified β-pinene styrene resin, functionalized nano-silica, and optimizing the melt blending process, these materials demonstrate superior overall performance. While maintaining low material hardness, these examples achieve high erasure efficiency, and the debris morphology is slender, exhibiting good paper protection. This technical solution effectively improves the common problems of traditional TPE eraser materials, such as decreased erasure rate when increasing hardness or poor erasure effect and easy paper damage when pursuing a soft feel. It can meet the application needs of the stationery industry for high-quality erasers with high cleaning efficiency and low paper damage.

[0047] Comparative Example 1, due to the omission of steps S1 and S2 for modifying and functionalizing the nano-silica powder, exhibits a difference in overall performance compared to the Example. Specifically, its surface hardness is higher than that of the Example, the fragment morphology is not improved, and the erasure rate is lower than that of the Example. This may be because the functionalized nano-silica, through surface modification groups, can form chemical bonds with elastomers or resins. This not only helps to inhibit filler agglomeration and thus alleviate the increase in overall material hardness, but also forms a fine dispersion state within the material, thus tending to produce fine strip-shaped fragments during wiping, reducing frictional damage to the paper surface. At the same time, the microscopic protrusion structure of the nanoparticles may have a certain scraping and adsorption effect on the pencil graphite, which helps to improve erasure efficiency. In the unmodified case, nano-silica is prone to agglomeration, resulting in higher material hardness, coarse fragment morphology, and insufficient erasure ability. This result indicates that functionalizing nano-silica and achieving its uniform dispersion with the matrix is ​​an important technical guarantee for optimizing the synergistic performance of material hardness, fragment morphology, and erasure rate.

[0048] Comparative Example 2 omitted step S2 and only used the silane coupling agent modified nano-silica powder obtained in step S1, resulting in a TPE eraser material with inferior overall performance compared to the example. This result indicates that omitting the in-situ polymerization grafting step leads to material performance degradation. The possible reason is that without the polymer grafting layer, the dispersion and interfacial compatibility of the nanofiller deteriorate, thereby affecting the material hardness, erasure rate, and paper protection. This result demonstrates the necessity of step S2 in the technical solution of this invention.

[0049] Comparative Example 3, lacking the phenol-modified β-pinene styrene resin component, exhibited significantly inferior overall performance compared to the Example, particularly in terms of erase rate and debris morphology. This is likely because the phenol-modified β-pinene styrene resin, as a core functional unit for flexibility enhancement and interfacial compatibility in the system, can reduce the overall hardness of the material and improve its softness through blending with elastomers. Furthermore, the resin's polar groups can form a stable interface with fillers and the matrix, promoting the generation of fine / strip-shaped debris and thus reducing paper damage. Simultaneously, the resin's swelling properties enhance the adsorption and transfer capacity of pencil graphite, improving the erase rate. The absence of this component resulted in higher material hardness, a sharp drop in erase rate, and coarser debris, ultimately leading to a double deterioration in both user experience and cleaning efficiency. These results demonstrate that the introduction of phenol-modified β-pinene styrene resin is a key and effective technical means to achieve a good balance between material softness, high erase rate, and paper protection.

[0050] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method of making a high eraser rate TPE eraser material, characterized by, Includes the following steps: Step 1: Modify the nano-silica powder with silane coupling agent KH574 and graft MMA and BA monomers in situ to obtain functionalized nano-silica powder. Step 2: Using phenol, β-pinene, and styrene as raw materials, phenol-modified β-pinene styrene resin is obtained under the action of Lewis acid catalyst; Step 3: Functionalized nano silica powder, phenol-modified β-pinene styrene resin, SEBS, antioxidant 1010, antioxidant 168, zinc stearate, paraffin oil and tributyl citrate are mixed, melt extruded and granulated to obtain high erasure rate TPE eraser material.

2. The method for preparing a high-erasability TPE eraser material according to claim 1, characterized in that, The mass ratio of the phenol-modified β-pinene styrene resin, SEBS, antioxidant 1010, antioxidant 168, lubricant zinc stearate, functionalized nano silica powder, paraffin oil, and tributyl citrate is 50-60:22-28:0.2-0.4:0.2-0.4:0.4-0.6:10-14:15-21:5-7.

3. The method for preparing a high-erasability TPE eraser material according to claim 1, characterized in that, The temperature of the melt extrusion is 120-155℃, and the screw speed is 200-300 r / min.

4. The method for preparing a high-erasability TPE eraser material according to claim 1, characterized in that, The specific preparation steps of the phenol-modified β-pinene styrene resin are as follows: The complex of methylcyclohexane and boron trifluoride diethyl ether was added to a reaction vessel and stirred at 250-350 r / min and -5-5℃ until homogeneous. The mixture was then added dropwise to the reaction vessel over 1 hour. After the addition was complete, the reaction was carried out at -2-2℃ for 3-5 hours. Phenol was then added to the vessel and the reaction was continued for 0.8-1.2 hours under the same conditions. The reaction was stopped by adding excess hot water and stirring was continued for 15-25 minutes. After the reaction solution cooled to room temperature, it was washed, separated from oil and water, and distilled under reduced pressure to obtain phenol-modified β-pinene styrene resin. The mass ratio of the methylcyclohexane, boron trifluoride diethyl ether complex, mixture and phenol is 90-100:6-7:82-100:7-8.

5.

5. The method for preparing a high-erasing-rate TPE eraser material according to claim 4, characterized in that, The mixture is composed of β-pinene and styrene in a mass ratio of 60-72:22-28.

6. The method for preparing a high-erasability TPE eraser material according to claim 1, characterized in that, The specific preparation steps of the functionalized nano-silica powder are as follows: Under a nitrogen atmosphere, a mixture of methyl methacrylate, butyl acrylate, azobisisobutyronitrile and methanol-water was added to a reaction vessel. Modified nano silica powder was then added to the reaction vessel. The reaction was carried out at 60-70℃ and 300-400 r / min for 10-14 h. After the reaction was completed, the product was collected, washed, and dried to obtain functionalized nano silica powder. The ratio of methyl methacrylate, butyl acrylate, azobisisobutyronitrile, methanol-water mixture and modified nano silica powder is 6-8g: 2-4g: 0.08-0.12g: 35-45mL: 4-6g.

7. The method for preparing a high-erasability TPE eraser material according to claim 6, characterized in that, The methanol-water mixture is prepared by mixing methanol and water in a volume ratio of 3:

1.

8. The method for preparing a high-erasability TPE eraser material according to claim 6, characterized in that, The specific preparation steps of the modified nano-silica powder are as follows: Nano-silica and n-butanol were added to a reaction vessel and ultrasonically dispersed evenly. Then, glacial acetic acid was added to adjust the pH to 5. KH574 modifier was slowly added dropwise to the reaction vessel. The reaction was carried out at 300-500 r / min and 98-102℃ for 5-7 h. After the reaction was completed, the mixture was centrifuged, washed, dried, ground, and sieved to obtain modified nano-silica powder. The ratio of nano-silica, n-butanol, and KH574 modifier is 4-6g: 45-55mL: 12-18g.

9. The method for preparing a high-erasability TPE eraser material according to claim 8, characterized in that, The KH574 modifier is obtained by mixing silane coupling agent KH574, deionized water and anhydrous ethanol in a mass ratio of 1.2-1.8:1.2-1.8:12-18.

10. A high eraser TPE material characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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