Sweat-resistant plastic material, process for its production and use in keycaps

Abstract

The application belongs to the technical field of plastic materials, and particularly relates to a sweat corrosion resistant plastic material, a preparation process thereof and an application in key caps. The sweat corrosion resistant plastic material comprises the following components in mass fraction: 40-60 parts of acrylonitrile-butadiene-styrene, 15-25 parts of PMMA resin, 20-30 parts of PVDF, 3-5 parts of a compatilizer, 4-7 parts of a hydroxyl-terminated polybutadiene, 0.5-1 part of an antioxidant, 5-9 parts of titanium white, and 0.5-1 part of an ultraviolet resistant additive. The sweat corrosion resistant plastic material prepared by the application has excellent sweat resistance, cold and hot impact resistance and aging resistance.

Description

Technical Field

[0001] This invention belongs to the field of plastic materials technology, specifically relating to sweat-resistant plastic materials, their preparation process, and their use in keycaps. Background Technology

[0002] Keyboard keycaps are small, cap-shaped plastic parts that attach to the top of the keys. They are marked with the function of the corresponding key or numbers and letters. During operation, users inevitably transfer sweat, oil, and other secretions to the device surface. Especially in high-temperature, high-humidity environments or during prolonged use, sweat can be corrosive to keycaps, easily leading to problems such as yellowing, cracking, loss of gloss, adhesion, and even reduced structural strength, severely affecting the product's appearance and lifespan.

[0003] Currently, commonly used keycap materials on the market mainly include thermoplastic engineering plastics such as ABS (acrylonitrile-butadiene-styrene copolymer), PBT (polybutylene terephthalate), and PC (polycarbonate). While these materials possess good processing performance and mechanical strength, they still exhibit varying degrees of degradation and aging under prolonged contact with sweat. Especially under conditions of significant acid-base changes, their corrosion resistance is noticeably insufficient, and their resistance to thermal shock is also poor. For example, patent CN115612240B discloses a keycap and its manufacturing method, comprising: 6080 parts modified ABS resin; 3050 parts PC resin; 37 parts compatibilizer; 28 parts antioxidant; and 10-20 parts polyacrylonitrile fiber. The modified ABS resin is obtained from ABS resin, rubber oil, montmorillonite, butadiene, and cumene hydroperoxide. This method improves the hardness of the keycap, but its corrosion resistance is not ideal.

[0004] Existing technologies improve the resistance of plastic materials to sweat corrosion through modification treatment and coating. For example, silane coupling agents are used to modify the base resin, or hydrophobic and oleophobic coatings are applied to the material surface to reduce the penetration and adhesion of sweat. However, these methods generally have problems such as complex processes, easy wear and peeling of coatings, and poor long-term stability, making it difficult to meet the dual requirements of material durability and economy in actual use.

[0005] Therefore, there is an urgent need for a sweat-resistant plastic material, its preparation process, and its application in keycaps. Summary of the Invention

[0006] The purpose of this invention is to provide a sweat-resistant plastic material, its preparation process, and its use in keycaps.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a sweat-resistant plastic material comprising the following components in parts by weight: 40-60 parts acrylonitrile-butadiene-styrene, 15-25 parts PMMA resin, 20-30 parts PVDF, 3-5 parts compatibilizer, 4-7 parts hydroxyl-terminated polybutadiene, 0.5-1 part antioxidant, 5-9 parts titanium dioxide, and 0.5-1 part UV resistant additive.

[0009] Preferably, the PVDF is the KR761 model from Arkema, France.

[0010] Preferably, the PMMA resin comprises the following raw materials in parts by weight: 0.8-1.2 parts acrylamide, 6-8 parts ethyl acrylate, 2-4 parts methyl methacrylate, 8-12 parts butyl methacrylate, 2-4 parts butyl acrylate, 0.5-1.5 parts acrylic acid, 0.5-1.5 parts azobisisobutyronitrile, and 60-70 parts ethyl acetate.

[0011] Preferably, the method for preparing the PMMA resin includes the following steps:

[0012] (1) Mix 70-75% of the total mass of methyl methacrylate, 70-75% of the total mass of ethyl acrylate, 35-40% of the total mass of acrylamide, 40-45% of the total mass of butyl methacrylate, 40-45% of the total mass of butyl acrylate, 40-45% of the total mass of acrylic acid, and all azobisisobutyronitrile evenly, and divide them into two equal parts by mass, namely component A and component C.

[0013] (2) Mix the remaining methyl methacrylate, ethyl acrylate, acrylamide, butyl methacrylate, butyl acrylate and acrylic acid evenly to obtain component B;

[0014] (3) Add ethyl acetate to the reaction vessel and heat it; add component A dropwise; then add component B dropwise; then add component C dropwise; after the dropwise addition is complete, keep it warm; filter to obtain PMMA resin.

[0015] Preferably, the mass ratio of acrylonitrile-butadiene-styrene, PMMA resin and PVDF is (50-55):(18-20):(23-25).

[0016] This invention improves the corrosion resistance of plastic materials by using self-made PMMA resin. At the same time, by adjusting the optimal proportion threshold of PVDF in the system, it can achieve the best match with ABS and PMMA, thereby improving the resistance to thermal shock and aging of plastic materials.

[0017] Preferably, the hydroxyl value of the hydroxyl-terminated polybutadiene is 0.54-0.64 mmol / g.

[0018] This invention improves the interfacial bonding strength, molecular chain mobility, and aging reactivity of adhesive materials by adding hydroxyl-terminated polybutadiene. By adding hydroxyl-terminated polybutadiene with a specific hydroxyl value, the plastic material can simultaneously achieve qualified impact strength and excellent aging resistance.

[0019] Preferably, the antioxidant is antioxidant 1010.

[0020] Preferably, the compatibilizer is maleic anhydride-grafted polypropylene.

[0021] This invention provides a process for preparing the sweat-resistant plastic material, comprising the following steps: mixing acrylonitrile-butadiene-styrene, PMMA resin, PVDF, maleic anhydride-grafted polypropylene and antioxidant, stirring, adding the remaining components, stirring, and extruding at a temperature using a twin-screw extruder to obtain the sweat-resistant plastic material.

[0022] This invention provides the application of the sweat-resistant plastic material in keycaps.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0024] 1. In daily use, components that frequently come into contact with human skin, such as keyboard keycaps, inevitably come into contact with sweat and occasional food residue or grease. Traditional plastic materials are prone to chemical degradation or physical deterioration under such conditions, leading to problems such as discoloration, cracking, and even a decrease in material strength. The sweat-resistant plastic material provided by this invention significantly enhances the material's resistance to sweat and cooking oil. This not only extends the product's lifespan but also improves the user experience, allowing users to enjoy stable and high-quality product performance in various usage scenarios.

[0025] 2. Electronic products may need to operate under extreme temperature conditions, such as when moving from a cold outdoor environment to a warm indoor environment. Rapid temperature changes can pose significant stress challenges to materials. The plastic material proposed in this invention possesses excellent resistance to thermal shock, meaning it can maintain structural integrity and functional stability over a wide temperature range. This is crucial for ensuring the reliability and durability of products under different climatic conditions, and is especially suitable for professional-grade or outdoor electronic products that need to be used in harsh environments.

[0026] 3. Keycaps and other components made from the materials prepared in this invention can maintain their initial good condition over a long period of time and are not easily degraded by environmental factors, thereby reducing maintenance costs and improving user satisfaction. Furthermore, the excellent aging resistance also helps reduce waste generation, aligning with the concept of sustainable development. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a sample prepared from the plastic material of Example 1 after a sweat test.

[0028] Figure 2 This is a schematic diagram of a sample prepared from the plastic material of Example 1 after being tested with edible oil.

[0029] Figure 3 This is a schematic diagram of the apparatus used for thermal shock testing of a sample prepared from the plastic material in Example 1.

[0030] Figure 4 This is a schematic diagram of a sample prepared from the plastic material of Example 1 after undergoing a thermal shock test. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] All raw materials used in the following embodiments of the present invention are commercially available products:

[0033] Acrylonitrile-butadiene-styrene, Kumho HFA705 from South Korea.

[0034] Maleic anhydride-grafted polypropylene, DuPont, USA.

[0035] Titanium dioxide, rutile titanium dioxide R-915, Shanghai Yantai E-commerce Co., Ltd.

[0036] UV absorber UV360, an anti-ultraviolet additive, is manufactured by Nanjing Milan Chemical Co., Ltd.

[0037] Example 1

[0038] This embodiment provides a sweat-resistant plastic material comprising the following components in parts by weight: 52 parts acrylonitrile-butadiene-styrene, 20 parts PMMA resin, 24 parts PVDF, 4 parts maleic anhydride-grafted polypropylene, 5 parts hydroxyl-terminated polybutadiene, 0.6 parts antioxidant 1010, 7 parts titanium dioxide, and 0.5 parts UV resistant additive.

[0039] PVDF is model KR761 from Arkema, France.

[0040] The hydroxyl value of hydroxyl-terminated polybutadiene is 0.54-0.64 mmol / g. Maclean, catalog number H909867.

[0041] The PMMA resin comprises the following raw materials in parts by weight: 1 part acrylamide, 7 parts ethyl acrylate, 3 parts methyl methacrylate, 10 parts butyl methacrylate, 3 parts butyl acrylate, 1 part acrylic acid, 1 part azobisisobutyronitrile, and 65 parts ethyl acetate.

[0042] The method for preparing the PMMA resin includes the following steps:

[0043] (1) Mix 75% of the total mass of methyl methacrylate, 75% of the total mass of ethyl acrylate, 40% of the total mass of acrylamide, 40% of the total mass of butyl methacrylate, 40% of the total mass of butyl acrylate, 40% of the total mass of acrylic acid, and all azobisisobutyronitrile evenly, and divide them into two parts with equal mass, namely component A and component C.

[0044] (2) Mix the remaining methyl methacrylate, ethyl acrylate, acrylamide, butyl methacrylate, butyl acrylate and acrylic acid evenly to obtain component B;

[0045] (3) Add ethyl acetate to the reactor and heat to 90°C; add component A dropwise for 1 hour; then add component B dropwise for 1 hour; then add component C dropwise for 1 hour; after the dropwise addition is complete, keep warm for 5 hours; cool down to room temperature of 25°C, filter, and obtain PMMA resin.

[0046] The preparation process of the sweat-resistant plastic material includes the following steps: mixing acrylonitrile-butadiene-styrene, PMMA resin, PVDF, maleic anhydride-grafted polypropylene and antioxidant, stirring for 2 minutes, adding the remaining components, stirring for 3 minutes, and extruding using a twin-screw extruder at the following temperatures: feeding zone: 100℃, melting zone: 175℃, mixing zone: 195℃, homogenization zone: 185℃, and die temperature: 190℃, to obtain the sweat-resistant plastic material.

[0047] Example 2

[0048] This embodiment provides a sweat-resistant plastic material comprising the following components in parts by weight: 50 parts acrylonitrile-butadiene-styrene, 18 parts PMMA resin, 25 parts PVDF, 3 parts maleic anhydride-grafted polypropylene, 7 parts hydroxyl-terminated polybutadiene, 0.5 parts antioxidant 1010, 9 parts titanium dioxide, and 0.5 parts UV resistant additive.

[0049] PVDF is model KR761 from Arkema, France.

[0050] The hydroxyl value of hydroxyl-terminated polybutadiene is 0.54-0.64 mmol / g. Maclean, catalog number H909867.

[0051] The PMMA resin comprises the following raw materials in parts by weight: 1 part acrylamide, 7 parts ethyl acrylate, 3 parts methyl methacrylate, 10 parts butyl methacrylate, 3 parts butyl acrylate, 1 part acrylic acid, 1 part azobisisobutyronitrile, and 65 parts ethyl acetate.

[0052] The method for preparing the PMMA resin includes the following steps:

[0053] (1) Mix 75% of the total mass of methyl methacrylate, 75% of the total mass of ethyl acrylate, 40% of the total mass of acrylamide, 40% of the total mass of butyl methacrylate, 40% of the total mass of butyl acrylate, 40% of the total mass of acrylic acid, and all azobisisobutyronitrile evenly, and divide them into two parts with equal mass, namely component A and component C.

[0054] (2) Mix the remaining methyl methacrylate, ethyl acrylate, acrylamide, butyl methacrylate, butyl acrylate and acrylic acid evenly to obtain component B;

[0055] (3) Add ethyl acetate to the reactor and heat to 90°C; add component A dropwise for 1 hour; then add component B dropwise for 1 hour; then add component C dropwise for 1 hour; after the dropwise addition is complete, keep warm for 5 hours; cool down to room temperature of 25°C, filter, and obtain PMMA resin.

[0056] The preparation process of the sweat-resistant plastic material includes the following steps: mixing acrylonitrile-butadiene-styrene, PMMA resin, PVDF, maleic anhydride-grafted polypropylene and antioxidant, stirring for 2 minutes, adding the remaining components, stirring for 3 minutes, and extruding using a twin-screw extruder at the following temperatures: feeding zone: 100℃, melting zone: 175℃, mixing zone: 195℃, homogenization zone: 185℃, and die temperature: 190℃, to obtain the sweat-resistant plastic material.

[0057] Example 3

[0058] This embodiment provides a sweat-resistant plastic material according to the first aspect of the present invention, comprising the following components in parts by weight: 55 parts acrylonitrile-butadiene-styrene, 20 parts PMMA resin, 23 parts PVDF, 3 parts maleic anhydride-grafted polypropylene, 7 parts hydroxyl-terminated polybutadiene, 0.5 parts antioxidant 1010, 9 parts titanium dioxide, and 0.5 parts UV resistant additive.

[0059] PVDF is model KR761 from Arkema, France.

[0060] The hydroxyl value of hydroxyl-terminated polybutadiene is 0.54-0.64 mmol / g. Maclean, catalog number H909867.

[0061] The PMMA resin comprises the following raw materials in parts by weight: 1 part acrylamide, 7 parts ethyl acrylate, 3 parts methyl methacrylate, 10 parts butyl methacrylate, 3 parts butyl acrylate, 1 part acrylic acid, 1 part azobisisobutyronitrile, and 65 parts ethyl acetate.

[0062] The method for preparing the PMMA resin includes the following steps:

[0063] (1) Mix 75% of the total mass of methyl methacrylate, 75% of the total mass of ethyl acrylate, 40% of the total mass of acrylamide, 40% of the total mass of butyl methacrylate, 40% of the total mass of butyl acrylate, 40% of the total mass of acrylic acid, and all azobisisobutyronitrile evenly, and divide them into two parts with equal mass, namely component A and component C.

[0064] (2) Mix the remaining methyl methacrylate, ethyl acrylate, acrylamide, butyl methacrylate, butyl acrylate and acrylic acid evenly to obtain component B;

[0065] (3) Add ethyl acetate to the reactor and heat to 90°C; add component A dropwise for 1 hour; then add component B dropwise for 1 hour; then add component C dropwise for 1 hour; after the dropwise addition is complete, keep warm for 5 hours; cool down to room temperature of 25°C, filter, and obtain PMMA resin.

[0066] The preparation process of the sweat-resistant plastic material includes the following steps: mixing acrylonitrile-butadiene-styrene, PMMA resin, PVDF, maleic anhydride-grafted polypropylene and antioxidant, stirring for 2 minutes, adding the remaining components, stirring for 3 minutes, and extruding using a twin-screw extruder at the following temperatures: feeding zone: 100℃, melting zone: 175℃, mixing zone: 195℃, homogenization zone: 185℃, and die temperature: 190℃, to obtain the sweat-resistant plastic material.

[0067] Comparative Example 1

[0068] The difference between this comparative example and Example 1 is that the sweat-resistant plastic material includes the following components in parts by weight: 48 parts acrylonitrile-butadiene-styrene, 16 parts PMMA resin, 30 parts PVDF, 4 parts maleic anhydride-grafted polypropylene, 5 parts hydroxyl-terminated polybutadiene, 0.6 parts antioxidant 1010, 7 parts titanium dioxide, and 0.5 parts UV resistant additive.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that the sweat-resistant plastic material includes the following components in parts by weight: 55 parts acrylonitrile-butadiene-styrene, 23 parts PMMA resin, 18 parts PVDF, 4 parts maleic anhydride-grafted polypropylene, 5 parts hydroxyl-terminated polybutadiene, 0.6 parts antioxidant 1010, 7 parts titanium dioxide, and 0.5 parts UV resistant additive.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that the PVDF used is from Arkema, France. Model 710.

[0073] Comparative Example 4

[0074] The difference between this comparative example and Example 1 is that the PVDF used is from Arkema, France. Model 740.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 is that the PMMA resin is a commercially available product, specifically Arkema from France, model HFI-10.

[0077] Comparative Example 6

[0078] The difference between this comparative example and Example 1 is that the hydroxyl value of the hydroxyl-terminated polybutadiene is 0.47-0.53 mmol / g. Maclean, catalog number H909866.

[0079] Comparative Example 7

[0080] The difference between this comparative example and Example 1 is that the hydroxyl value of the hydroxyl-terminated polybutadiene is 0.71-0.80 mmol / g. Maclean, catalog number H909869.

[0081] Performance testing

[0082] The sweat-resistant plastic materials prepared in Examples 1-3 and Comparative Examples 1-7 were injection molded at 185°C, cooled, and then heat-treated in an oven at 80°C for 2 hours to obtain samples with a wall thickness of 1.5 mm. The following performance tests were then conducted.

[0083] 1. Corrosion resistance test:

[0084] (1) Sweat test: Add 50g of lactic acid and 100g of sodium chloride to a container, dissolve them in 900ml of water, and bring the volume to 1 liter to prepare artificial sweat. Place the sample flat in the container, 15cm away from the surface of the artificial sweat, seal the container, and place it in an oven at 55±5℃ for 48 hours. Remove the sample, rinse it with water, and let it air dry naturally. Observe whether there is any color change or obvious decomposition on the surface.

[0085] (2) Edible oil test: Test standard: Drop the edible oil on a cotton cloth, apply a 500G force and wipe back and forth on the paint film surface for 100,000 times, and observe whether there are any damages or exposed substrate phenomena.

[0086] 2. Thermal shock test: Test conditions: Place the sample at 65°C and -30°C for 2 hours each in turn, make one cycle, and conduct a total of 24 cycle tests.

[0087] Detection standard:

[0088] (1) There are no appearance defects during and after the test;

[0089] (2) The keycaps have no bulges or cracks.

[0090] Completely meeting the detection standard is considered qualified, and if at least one item does not meet, it is recorded as unqualified. Figure 3-4 .

[0091] 3. Tensile strength: Refer to GB / T1040.2-2022 to determine the original tensile strength of the sample.

[0092] 4. Aging resistance: Place at 85°C / 85%RH for 336 hours, and calculate the tensile strength retention rate after aging = tensile strength of the sample after aging ÷ original tensile strength of the sample × 100%.

[0093] The results are shown in Table 1.

[0094] Table 1 Performance test results

[0095]

[0096]

[0097] According to Figure 1-4 and Table 1, it can be seen that the comprehensive performance of the plastic materials in Examples 1-3 is more excellent.

[0098] In Comparative Example 1, the content of PVDF increases and that of ABS / PMMA decreases. In Comparative Example 2, the content of PVDF decreases and that of ABS / PMMA increases. Both thermal shock tests are unqualified. This shows that there is an optimal proportion threshold of PVDF in the system, achieving the best match with the thermal expansion coefficients of ABS / PMMA.

[0099] Comparative Examples 3 and 4 show that the type of PVDF used in the present invention has an important influence on the performance of the plastic material. Using the KR761 type from Arkema France has better compatibility and processing performance with other components in the system, and the material has stronger resistance to thermal shock.

[0100] Comparative Example 5 shows that using commercially available PMMA reduces the tensile strength of the plastic material.

[0101] Comparative Examples 6 and 7 show that the hydroxyl value of hydroxyl-terminated polybutadiene affects the aging resistance of plastic materials. In Comparative Example 6, a lower hydroxyl value improves thermal shock resistance but deteriorates aging resistance. In Comparative Example 7, an increased hydroxyl value improves aging resistance but decreases thermal shock resistance. The hydroxyl-terminated polybutadiene used in Examples 1-3 maintains both acceptable impact resistance and excellent aging resistance.

[0102] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sweat-resistant plastic material, characterized in that, The product comprises the following components in parts by weight: 50-55 parts acrylonitrile-butadiene-styrene, 18-20 parts PMMA resin, 23-25 ​​parts PVDF, 3-5 parts compatibilizer, 4-7 parts hydroxyl-terminated polybutadiene, 0.5-1 part antioxidant, 5-9 parts titanium dioxide, and 0.5-1 part UV stabilizer. The PMMA resin comprises the following components in parts by weight: 0.8-1.2 parts acrylamide, 6-8 parts ethyl acrylate, 2-4 parts methyl methacrylate, 8-12 parts butyl methacrylate, 2-4 parts butyl acrylate, 0.5-1.5 parts acrylic acid, 0.5-1.5 parts azobisisobutyronitrile, 60-70 parts ethyl acetate; The method for preparing the PMMA resin includes the following steps: (1) Mix 70-75% of the total mass of methyl methacrylate, 70-75% of the total mass of ethyl acrylate, 35-40% of the total mass of acrylamide, 40-45% of the total mass of butyl methacrylate, 40-45% of the total mass of butyl acrylate, 40-45% of the total mass of acrylic acid, and all azobisisobutyronitrile evenly, and divide them into two parts with equal mass, namely component A and component C. (2) Mix the remaining methyl methacrylate, ethyl acrylate, acrylamide, butyl methacrylate, butyl acrylate and acrylic acid evenly to obtain component B; (3) Add ethyl acetate to the reaction vessel and heat; Add component A dropwise; then add component B dropwise; then add component C dropwise; after the addition is complete, keep warm; filter to obtain PMMA resin; The hydroxyl value of hydroxyl-terminated polybutadiene is 0.54-0.64 mmol / g; The PVDF is KR761 from Arkema, France, and the compatibilizer is maleic anhydride-grafted polypropylene.

2. The sweat-resistant plastic material according to claim 1, characterized in that, The antioxidant is antioxidant 1010.

3. A preparation process for a sweat-resistant plastic material according to any one of claims 1-2, characterized in that, Includes the following steps: Acrylonitrile-butadiene-styrene, PMMA resin, PVDF, maleic anhydride-grafted polypropylene and antioxidant are mixed and stirred. The remaining components are then added and stirred. The mixture is extruded using a twin-screw extruder at a certain temperature to obtain a sweat-resistant plastic material.

4. The application of the sweat-resistant plastic material according to any one of claims 1-2 in keycaps.

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