Keycap containing furanoate polyester

Abstract

The present invention relates to a keycap on top of a switching mechanism used as part of an integrated or peripheral keyboard or individual switches. The keycap includes a polymer of butylene 2,5-furandicarboxylate (PBF), a polymer of butylene bifuranate (PBBf), a copolymer of butylene 2,5-furandicarboxylate (BF) and butylene bifuranate (BBf), a copolymer of ethylene 2,5-furandicarboxylate (EF) and one or both of BF and BBf, a copolymer of (i) butylene terephthalate (BT) and (ii) one or more of BF, BBf and EF, or combinations thereof. The keycap is configured to be attached on top of a switching mechanism of a key of a keyboard.

Description

Technical Field

[0001] The disclosed teachings relate to keycaps made of bio-based materials.

Background Art

[0002] Alphanumeric keyboards are an important input peripheral or integrated part of any modern computer and are used to input information in the form of characters consisting of letters, numbers, and other special characters. Alphanumeric keyboards typically have 80 to 110 buttons or keys labeled with one or more characters. Pressing an individual button or combination of buttons on the keyboard inputs the desired character.

[0003] Numeric keys are typically found across the top of the keyboard and usually also on the right side of larger keyboards. Alphabetic keys are typically found in the center of the keyboard. Recent keyboards also include control processors and indicator lights to provide feedback to the user about the state of the keyboard and whether specific keys, such as the "caps lock" key, are active.

[0004] Each key of the keyboard generally includes a durable switch. Various types of keyboards using various switch technologies have been developed, such as membrane, dome switch, scissor switch, capacitive, mechanical, magnetic hall effect, or optical. Each type has its advantages and disadvantages, but generally the choice of switch technology affects key response (the positive feedback that the key has been pressed) and pre-travel (the distance required to press the key to reliably input a character).

[0005] For example, in a mechanical switch keyboard, each key contains a complete switch under the keycap. Each switch is composed of a housing, a spring, and a stem, and may also be composed of other components such as tactile leaves or click bars. There are three types of mechanical switches (www.wikiwand.com / en / List_of_keyboard_switches): "linear" with a constant resistance, "tactile" where no bump sound can be heard, and "clicky" with both a bump and a click sound. Depending on the resistance of the spring, the keys require different amounts of pressure to activate and bottom out.

[0006] Another example is a dome switch keyboard. In this design, an upper membrane with circuit traces and contact pads at the bottom and a bottom membrane with circuit traces and contact pads at the top are separated by a central membrane with holes. The keycap attached to the rubber dome is positioned above the upper membrane. When the keycap is pressed, the circuits of the upper and bottom membranes come into contact with each other.

[0007] Yet another example is a scissor switch keyboard. In this design, the keycap is attached to the keyboard via two plastic pieces that interlock in a "scissor" shape and snap onto the keyboard and the key. It uses a rubber dome similar to a dome switch keyboard, but a special plastic "scissor" mechanism (www.wikiwand.com / en / Scissors_mechanism) links the keycap (www.wikiwand.com / en / Keycap) to a plunger that presses down on the rubber dome with a much shorter movement than a typical rubber dome keyboard. Typically, a scissor switch keyboard also employs a three-layer membrane as the electrical component of the switch.

[0008] What is common to the above keyboard designs is that keycaps labeled with respective characters are attached on top of switches. These keycaps can typically be removed for cleaning of the switch mechanism and replacement of damaged or worn keycaps.

[0009] Recent keycaps are typically surface printed, but double shot molding (www.wikiwand.com / en / Injection_molding#Multi-shot_moulding), laser printing, sublimation printing, or engraving are also possible.

[0010] Keycaps are injection molded parts. Injection molding is a manufacturing process for producing parts by injecting molten material into a mold. Injection molding can be carried out using many materials including metals, glasses, elastomers, and most commonly thermoplastic and thermosetting polymers (e.g., thermoplastic resins).

[0011] Since keys may be pressed over one million times during the life of a keyboard, keycaps need to be made from wear-resistant materials such as polybutylene terephthalate (PBT).

[0012] PBT has many attractive properties such as high mechanical strength and toughness, high abrasion resistance, excellent dimensional stability, high heat distortion temperature (up to 215 °C for glass fiber-reinforced PBT), fast crystallization rate, high continuous use at high temperatures (e.g., 140 °C) due to low mechanical creep, good chemical resistance, and short processing cycle times in injection molding. Due to these properties, PBT can be found in many applications such as automotive electrical connectors (「automotive connectors」) and keycaps for keyboards. Thus, the global demand for PBT continues to increase. PBT can be synthesized by a two-step process via the melt polycondensation method. First, bis(4-hydroxybutyl) terephthalate (BHBT) is formed by the transesterification of dimethyl terephthalate (DMT) and 1,4-butanediol (BD). Then, BD is removed from BHBT in the polycondensation step to form PBT. Other synthetic routes include polymerization after a ring-opening or enzymatic approach.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Non-Patent Documents

[0014]

Non-Patent Document 1

Non-Patent Document 2

[0015] Concerns regarding climate change due to global warming caused by greenhouse gas (GHG) emissions are increasing both legislative and social pressures on manufacturers and consumers to reduce carbon emissions. As a result, both manufacturers and consumers are motivated to reduce the use of products derived from petrochemical materials. Furthermore, manufacturers need to replace materials derived from fossil fuels, which generate new carbon emissions as they are used, with materials derived from biomass (i.e., renewable carbon) in the not-too-distant future.

[0016] DMT used in the synthesis of PBT is derived from petrochemical feedstocks; thus, the use of PBT results in a positive carbon footprint and should therefore be replaced by bio-based polyesters with similar chemical and physical properties.

[0017] There is a need for a substantially biomass-derived injection-moldable polymer having properties substantially similar to those of fossil-fuel-derived PBT that can serve as an alternative material to PBT in keycap applications.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0019] One or more embodiments of the present disclosure are shown by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals indicate like elements.

[0020] Abbreviations BF: Butylene 2,5-furandicarboxylate. BBf: Butylene bifuranate. EF: Ethylene 2,5-furandicarboxylate. BT: Butylene terephthalate. PBT: Polybutylene terephthalate, also called a polymer of butylene terephthalate. PBF: Poly(butylene 2,5-furandicarboxylate), also called a polymer of butylene 2,5-furandicarboxylate. PBBf: Poly(butylene bifuranate), also called a polymer of butylene bifuranate. PEF: Poly(ethylene 2,5-furandicarboxylate), also called a polymer of ethylene 2,5-furandicarboxylate.

[0021]

Chemical Formula

[0022] The present disclosure describes an improved keycap by replacing a polybutylene terephthalate (PBT)-based keycap with a poly(butylene 2,5-furandicarboxylate) (PBF)-based keycap. PBF is an aromatic polyester that is chemically similar to PBT and exhibits similar chemical and physical properties, and thus is a potential alternative material for PBT. PBT is derived from fossil fuel-based feedstocks, while PBF is derived from bio-based feedstocks and has a lower carbon footprint than PBT.

[0023] PBF is similar to PBT, differing only in chemical structure by including a furan ring instead of a benzene ring. The building block of PBF is 2,5-furandicarboxylic acid (FDCA). FDCA can be produced by the catalytic conversion of 5-hydroxymethylfurfural (HMF), which can be generated by the acid-catalyzed dehydration of fructose. PBF, like PBT, can be synthesized in a two-step process by melt polycondensation. First, dimethyl 2,5-furandicarboxylate (DMFD) is formed via the esterification of FDCA with methanol. Second, bis(hydroxybutyl)-2,5-furandicarboxylate (BHFD) is formed via the transesterification of DMFD with 1,4-butanediol (BD). Then, BD is removed from BHFD in the polycondensation step to form PBF. This process is described, for example, in M. Papageorgiou et al., "Evaluation of polyesters from renewable resources as alternatives to the current fossil-based polymers. Phase transitions of poly(butylene 2,5-furan-dicarboxylate)", Polymer 55, 3846 (2014) (Non-Patent Document 1). Alternative synthetic methods using ring-opening polymerization are described, for example, in J.C. Morales-Huerta et al., "Poly(alkylene 2,5-furandicarboxylate)s (PEF and PBF) by ring opening", Polymer 87, 148 (2016) (Non-Patent Document 2).

[0024] Due to their chemical similarities, PBF and PBT generally exhibit similar properties. However, PBF shows superior gas diffusion barrier properties against oxygen and CO2 compared to those of PBT. This is based on the lower symmetry of the furan ring in PBF compared to the benzene ring in PBT, resulting in very limited local motion in PBF, particularly the flipping of the constrained furan ring and the restricted carbonyl rotation that reduce the diffusion of low molecules.

[0025] The keycap can be injection molded using a thermoplastic resin. For example, polyamides such as nylon, polyacetals such as polyoxymethylene, polyolefins such as polypropylene, polyesters such as polyethylene terephthalate and PBT, polycarbonate, polyphenylene sulfide, etc. may be mentioned. Among these, PBT is often used because it has desirable mechanical properties (e.g., tensile modulus and tensile strength), electrical properties, heat resistance, water resistance, and good dimensional stability required for the keycap. Also, PBT is a semi-crystalline resin with a high crystallization rate and solidifies in a short time, so the productivity is high. Due to these advantages, PBT is widely used as a molding material for keycaps. In the conventional practice, in order to strengthen PBT as a molding material for keycaps, a reinforcing additive (e.g., fiber) is added to PBT. Due to the chemical similarity of PBF to PBT, the same technique of adding a reinforcing additive can be applied to PBF.

[0026] The disadvantage of PBF compared to PBT regarding its use in keycaps is a lower melting temperature of 168°C to 186°C compared to the melting temperature of PBT of 221°C to 225°C. The present disclosure also describes a blend of PBF and PBT to overcome this disadvantage. As a result, savings in GHG emissions and non-renewable energy use (NREU) are achieved, but are reduced in proportion to the reduction in the PBT content.

[0027] To overcome the disadvantage of the lower melting temperature of 168°C to 186°C of PBF related to its use in keycaps, the present disclosure also describes blends and copolymers of PBF and PEF. The melting temperature of PEF is in the range of 202°C to 220°C. Similar to PBF, the basic component of PEF is FDCA. The resulting PEF is a bio-based polymer, and thus significant savings in GHG emissions and NREU are achieved by the combination of PBF and PEF.

[0028] PBF and PEF have a slower crystallization rate resulting from the rigidity of the furan ring compared to PBT. The present disclosure also describes the use of nucleating agents, additives, and fillers to increase the crystallization rate and nucleation density of PBF or PEF and related blends, copolymers, and composites.

[0029] The present disclosure also describes the use of poly(butylene bifuranate) (PBBf) also derived from FDCA and 2,2'-bifuran-5,5'-dicarboxylic acid (BFDCA) in keycaps. PBBf has a melting temperature of 215 °C to 217 °C. BFDCA, which is a precursor of PBBf, is derived from the homogeneous Pd-catalyzed oxidative homocoupling of methyl 2-furoate (a renewable feedstock) with molecular oxygen as the oxidant as described in Mingchun Ye et al., "Oxidative coupling of 2-methyl furoate: A scalable synthesis of dimethyl 2,2'-bifuran-5,5'-dicarboxylate", Applied Catalysis A: General, 619, 118138 (2021) (Non-Patent Document 3).

[0030] Table 1 lists the relevant properties of PBT, PBF, PBBf, and PEF. The properties include tensile modulus, tensile strength, elongation at break, glass transition temperature (T g g), and melting temperature (T m m).

[0031]

Table 1

[0032] FIG. 1 shows a perspective view of a sample electronic device 100 including a plurality of keys 102. As shown, the electronic device 100 is a portable laptop computer including an integrated keyboard 104 including a plurality of key columns 102 with at least one keycap attached to the top of a switching mechanism. The electronic device 100 may be a laptop computer as shown, but other electronic devices characterized by a keyboard with keycaps are contemplated, such as desktop computers, peripheral input devices (e.g., peripheral keyboards), mobile phones, wearable devices, health devices, etc. The keys may further be individual electronic components such as switches or contactors for inclusion within a number of circuits or devices.

[0033] FIG. 2A shows a side cross-sectional view of an exemplary key 200. The key 200 may include a keycap 202 having at least one retaining mechanism 202a. The keycap 202 may be constructed of any suitable durable material such as PBT or an alternative polymer material as disclosed in the present invention.

[0034] FIG. 2B shows an exploded perspective view of the keycap 202 on a scissor mechanism having scissor members 204 and 206 and an elastic member 210 having a frame 210a and an elastic portion 210b that can be mounted on a circuit board 212 located above a support frame 214 having a plurality of mounting brackets. The scissor members 204 and 206 have a plurality of connection portions that are attached to respective mounting brackets of the keycap 202 and the support frame 214.

[0035] Referring to FIG. 2C, the keycap 202 has an inner surface having a first pair of mounting brackets 202b attached to the connection portion of the scissor member 204 and a second pair of mounting brackets 202c attached to the connection portion of the scissor member 206.

[0036] The keycap 202 may be disposed above a scissor mechanism defined by scissor members 204, 206. The scissor member 204 may be positioned to interface with the bottom surface of the keycap 202. For example, the scissor member 204 may include an upper surface that is partially angled such that when the key 200 is in the "up" position, the angled portion is parallel to the bottom surface of the keycap 202. In this way, the geometric shape selected for the scissor member 204 may assist in the structural support of the keycap 202. The scissor member 206 may interface with the retaining mechanism 202a. In this way, when the keycap is depressed, the scissor member 206 can pivot at the retaining mechanism 202a to fold the scissor mechanism of the key 200 downward.

[0037] The scissor mechanism can be disposed above a base plate 208 which may also include at least one retaining mechanism 208a. The base plate may be constructed from a number of suitable materials such as aluminum or steel.

[0038] FIG. 3 shows an exemplary molding machine 300 for performing an injection molding process. In the injection molding machine 300, one or more fixed molds 301 and the same number of movable molds 302 as the fixed molds 301 are arranged to face each other. By clamping each set of the fixed mold 301 and the movable mold 302, a cavity having the shape of an injection molded product is formed. The molten material is injected into the cavity between the fixed mold 301 and the movable mold 302 and is held in contact with the molten material for a predetermined time until it is sufficiently cooled and solidified. Then, by moving the movable mold 302 in the mold opening direction by a predetermined amount and retracting it from the opposing fixed mold 301 by servo motor control or hydraulic control, the injection molded product can be taken out. The molding machine 300 can be used to manufacture keycaps such as those described with respect to FIGS. 1, 2A, 2B, and 2C from thermoplastic materials including PBF, PBBf, polymer blends (also referred to as "blends"), or any combination of BF, BBf, EF, or BT copolymers, any combination thereof, or any combination thereof in a blend with PBT, or any combination thereof in a blend with PEF.

[0039] (Keycap) According to some embodiments of the present disclosure, the keycap is attached to the upper part of a switching mechanism of a key that is part of an integral keyboard or a peripheral keyboard or an individual electronic switch. Exemplary keycaps include the keycap 202 on the upper part of the scissor switch mechanism described with respect to FIG. 2, which is commonly used for the laptop keyboard 102 described with respect to FIG. 1.

[0040] In one preferred embodiment, the keycap can include PBF, PBBf, a copolymer of (i) BF and (ii) BBf, a copolymer of (i) EF and one or both of (ii) BF and BBf, a copolymer of (i) BT and one or more of (ii) BF, BBf, and EF, or any combination thereof. The polymers and / or copolymers can be in any combination, alone or as a polymer blend (mixture). For example, the keycap can include a copolymer of EF and BF, a copolymer of EF and BBf, a copolymer of EF, BF, and BBf, a copolymer of BT and BF, a copolymer of BT and BBf, a copolymer of BT and EF, a copolymer of BT, BF, and BBf, a copolymer of BT, BF, and EF, a copolymer of BT, BBf, and EF, a copolymer of BT, BF, BBf, and EF, or any combination thereof. In another example, the keycap can include a polymer blend of PBF and PBBf, a polymer blend of PEF and PBF, a polymer blend of PEF and PBBf, a polymer blend of PEF, PBF, and PBBf, a polymer blend of PBT and PBF, a polymer blend of PBT and PBBf, a polymer blend of PBT and PEF, a polymer blend of PBT, PBF, and PBBf, a polymer blend of PBT, PBF, and PEF, a polymer blend of PBT, PBBf, and PEF, a polymer blend of PBT, PBF, PBBf, and PEF, or any combination thereof.

[0041] The keycap can include any of the following polymers or copolymers, alone or in any combination as a polymer blend: PBF, PBBf, a blend (mixture) or copolymer of BF and BBf, a blend or copolymer of EF and one or both of BF and BBf, or a blend or copolymer of BT and one or more of BF, BBf, and EF.

[0042] The copolymer of BT and BF, BT and BBf, or BT and BF and BBf can contain 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt%, or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt%, or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of BT.

[0043] In some embodiments, the keycap further comprises PBT. The keycap can comprise a polymer blend containing PBT in, for example, PBF, PBBf, a copolymer of BF and BBf, a copolymer of BT and BF, a copolymer of BT and BBf, or any combination with a copolymer of BT and BF and BBf.

[0044] In some embodiments, the keycap comprises a blend of PBT and PBF. The blend of PBT and PBF can contain 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBT.

[0045] In some embodiments, the keycap comprises a blend of PBT and PBBf. The blend of PBT and PBBf can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBT.

[0046] In some embodiments, the keycap comprises a blend of PBT and a copolymer of BF and BBf. The blend of PBT and the copolymer of BF and BBf can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBT.

[0047] In some embodiments, the keycap comprises a copolymer of BF and BBf. The copolymer of BF and BBf can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of BBf.

[0048] In some embodiments, the keycap comprises a blend of PBF and PBBf. The blend of PBF and PBBf can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBF.

[0049] In some embodiments, the keycap comprises a copolymer of BF and EF. The copolymer of BF and EF can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of BF.

[0050] In some embodiments, the keycap comprises a blend of PBF and PEF. The blend of PBF and PEF can comprise 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBF.

[0051] The weight percent of each component in the blend or copolymer is selected based on the desired properties to be achieved in the material. For example, PBT (T m = 221 - 225 °C) and PBF (T mIn a blend (168 - 186 °C), the weight percentages of PBT and PBF can be selected to obtain the desired melting temperature of the blend between those of the pure polymers.

[0052] In some embodiments, the keycap further includes additives. The additives can be selected from, but are not limited to, antioxidants, ultraviolet (UV) stabilizers, flame retardants, hydrolysis inhibitors, coloring pigments, nucleating agents, additives or fillers for increasing crystallization rate and / or mechanical strength, additives for laser marking, lubricants, and waxes. For example, the keycap can include 0.1 - 3 wt%, 0.1 - 5 wt%, or 0.1 - 10 wt% of an antioxidant such as a sterically hindered phenolic thioether, phosphite, or any combination thereof; for example, the keycap can include 0.1 - 10 wt% of a UV stabilizer such as benzotriazole, hydroxybenzophenone, or any combination thereof; for example, the keycap can include 1 - 40 wt%, 2 - 30 wt%, or 5 - 25 wt% of a flame retardant such as a phosphate ether, magnesium hydroxide, aluminum diethylphosphinate, or any combination thereof; and / or, for example, the keycap can include 0.1 - 10 wt% of a hydrolysis inhibitor such as an acid scavenger; and / or, for example, the keycap can include 0.1 - 20 wt% of a coloring pigment such as anthraquinone, iron oxide, carbon black, titanium dioxide, orange pigment. Examples of lubricants can include polytetrafluoroethylene (PTFE), esters, and / or metal salts of fatty acids such as zinc stearate, calcium stearate, and adipic acid glycol polyester (AAGP). Examples of nucleating agents or crystallization rate improvers can include sodium benzoate, sodium salt of saccharin, boron nitride, organic acids, metal salts, inorganic substances such as carbon nanotubes (CNT), talc, glass fiber, or metal carbonate, and / or coupling agents. Examples of waxes can include ethylene bis stearamide.

[0053] In some embodiments, the additive is a discoloring additive for laser engraving. This additive has no or substantially no inherent color (only a slight inherent color) in the visible spectrum range (light wavelengths of approximately 380 - 750 nm), and under the influence of laser light with a wavelength outside the visible range (less than 380 nm or more than 750 nm), it generates markings with high color contrast in the visible range. The color contrast can be generated, for example, by the additive changing into a colored product under the influence of laser light from an Nd - YAG laser (wavelength 1064 nm) or an excimer laser (wavelength 308 nm - 351 nm). Any additive having the above characteristics, such as copper phosphate, copper sulfate, basic copper phosphate hydroxide, and copper thiocyanate, for example, 0.02% - 5% of Cu3(PO4)2·Cu(OH)2 can be used for laser engraving.

[0054] In some embodiments, the additive is a reinforcing additive. For example, the keycap contains 1 - 60 wt%, 2 - 50 wt%, or 5 - 40 wt% of the reinforcing additive. The reinforcing additive can be selected from, but is not limited to, glass fiber, carbon fiber, talc, cellulose, bamboo, softwood, hardwood, flax, kenaf, jute, ramie, coir, kapok, sisal, henequen, abaca, hemp, bagasse, wheat straw, rice husk, corn, sunn, and any combination thereof.

[0055] In some embodiments, the keycap has a tensile modulus in the range of about 1 - 4 GPa, 2 - 4 GPa, 3 - 7 GPa, or 5 - 7 GPa, and a tensile strength in the range of about 20 - 70 MPa, 40 - 70 MPa, 20 - 90 MPa, 40 - 90 MPa, 50 - 150 MPa, 90 - 150 MPa, 20 - 95 MPa, or 40 - 95 MPa.

[0056] Exemplary ranges of tensile modulus and tensile strength are provided in Examples I - X. By compounding PBF and / or PBBf, or a copolymer of BF and BBf, with a reinforcing additive, the tensile modulus and tensile strength of the keycap increase. For example, the tensile modulus of PBF ranges from 1 - 4 GPa, preferably from 2 - 4 GPa, the maximum tensile strength of PBF ranges from 20 - 70 MPa, preferably from 40 - 70 MPa, the tensile modulus of the composite of PBF and the reinforcing additive ranges from 3 - 7 GPa, preferably from 5 - 7 GPa, the maximum tensile strength of the composite of PBF and the reinforcing additive ranges from 50 - 150 MPa, preferably from 90 - 150 MPa, the tensile modulus of the PBF / PBT blend ranges from 1 - 4 GPa, preferably from 2 - 4 GPa, the maximum tensile strength of the PBF / PBT blend ranges from 20 - 70 MPa, preferably from 40 - 70 MPa, the tensile modulus of PBBf ranges from 1 - 4 GPa, preferably from 2 - 4 GPa, the maximum tensile strength of PBBf ranges from 40 - 90 MPa, preferably from 55 - 90 MPa, the tensile modulus of the composite of PBBf and the reinforcing additive ranges from 3 - 7 GPa, preferably from 5 - 7 GPa, the maximum tensile strength of the composite of PBBf and the reinforcing additive ranges from 50 - 150 MPa, preferably from 90 - 150 MPa, the tensile modulus of the PBF / PBBf blend or the copolymer of BF and BBf ranges from 1 - 4 GPa, preferably from 2 - 4 GPa, the maximum tensile strength of the PBF / PBBf blend or the copolymer of BF and BBf ranges from 20 - 90 MPa, preferably from 40 - 90 MPa, the tensile modulus of the PBF / PBBf blend or the copolymer of BF and BBf with the reinforcing additive added ranges from 3 - 7 GPa, preferably from 5 - 7 GPa, and the maximum tensile strength of the PBF / PBBf blend or the copolymer of BF and BBf with the reinforcing additive added ranges from 50 - 150 MPa, preferably from 90 - 150 MPa.

[0057] The tensile modulus of the PBF / PEF blend or the copolymer of BF and EF is in the range of 1 to 4 GPa, preferably in the range of 2 to 4 GPa, and the maximum tensile strength of the PBF / PEF blend or the copolymer of BF and EF is in the range of 20 to 95 MPa, preferably in the range of 40 to 95 MPa. The tensile modulus of the PBF / PEF blend or the copolymer of BF and EF and the reinforcing additive is in the range of 3 to 7 GPa, preferably in the range of 5 to 7 GPa, and the maximum tensile strength of the PBF / PBBf blend or the copolymer of BF and BBf and the reinforcing additive is in the range of 50 to 150 MPa, preferably in the range of 90 to 150 MPa. The tensile modulus of the PBBf / PEF blend or the copolymer of BBf and EF is in the range of 1 to 4 GPa, preferably in the range of 2 to 4 GPa, and the maximum tensile strength of the PBBf / PEF blend or the copolymer of BBf and EF is in the range of 20 to 95 MPa, preferably in the range of 40 to 95 MPa. The tensile modulus of the PBBf / PEF blend or the copolymer of BBf and EF and the reinforcing additive is in the range of 3 to 7 GPa, preferably in the range of 5 to 7 GPa, and the maximum tensile strength of the PBBf / PEF blend or the copolymer of BBf and EF and the reinforcing additive is in the range of 50 to 150 MPa, preferably in the range of 90 to 150 MPa.

[0058] In some embodiments, the keycap has a load deflection temperature in the range of 60°C to 150°C, 80°C to 150°C, or 100°C to 150°C.

[0059] PBF can be synthesized as described in Papageorgiou et al., "Evaluation of polyesters from renewable resources as alternatives to the current fossil-based polymers. Phase transitions of poly(butylene 2,5-furan-dicarboxylate)", Polymer 55, 3846 (2014) (Non-Patent Document 1) or J.C. Morales-Huerta et al., "Poly(alkylene 2,5-furandicarboxylate)s (PEF and PBF) by ring opening", Polymer 87, 148 (2016) (Non-Patent Document 2). BFDCA, which is the precursor of PBBf, can be synthesized as described in Mingchun Ye et al., "Oxidative coupling of 2-methyl furoate: A scalable synthesis of dimethyl 2,2'-bifuran-5,5'-dicarboxylate", Applied Catalysis A: General, 619, 118138 (2021) (Non-Patent Document 3), and PBBf can be synthesized from the precursor BFDCA as described in T. Kainulainen et al., "Utilizing Furfural-Based Bifuran Diester as Monomer and Comonomer for High-Performance Bioplastics: Properties of Poly(butylene furanoate), Poly(butylene bifuranoate), and Their Copolyesters", Biomacromolecules 21, 743 (2020) (Non-Patent Document 4). The synthesis of random copolymers of BF and BBf is also described in Kainulainen et al., Biomacromolecules 21, 743-752 (2020) (Non-Patent Document 4).The blend of PBF and PEF is described in Poulopoulou et al., "Green polymeric materials: On the dynamic homogeneity and miscibility of furan-based polyester blends", Polymer 174, 187-199 (2019) (Non-Patent Document 5). All of the references cited herein are incorporated by reference in their entirety.

[0060] (Manufacturing process of keycap) FIG. 4 is a flowchart showing a process 400 for manufacturing a keycap. In some embodiments, the keycap corresponds to the exemplary keycap described with respect to FIGS. 1 and 2 (A-C).

[0061] In 402, process 400 includes obtaining one or more materials. In some embodiments, the one or more materials are selected from the group consisting of PBF, PBBf, a copolymer of (i) BF and (ii) BBf, a copolymer of (i) EF and (ii) one or both of BF and BBf, a copolymer of (i) BT and (ii) one or more of BF, BBf, and EF, or any combination thereof. The polymers and / or copolymers can be in any combination, alone or as a polymer blend (mixture). For example, the one or more materials can include a copolymer of EF and BF, a copolymer of EF and BBf, a copolymer of EF, BF, and BBf, a copolymer of BT and BF, a copolymer of BT and BBf, a copolymer of BT and EF, a copolymer of BT, BF, and BBf, a copolymer of BT, BF, and EF, a copolymer of BT, BBf, and EF, a copolymer of BT, BF, BBf, and EF, or any combination thereof. For example, the one or more materials can include a polymer blend of PBF and PBBf, a polymer blend of PEF and PBF, a polymer blend of PEF and PBBf, a polymer blend of PEF, PBF, and PBBf, a polymer blend of PBT and PBF, a polymer blend of PBT and PBBf, a polymer blend of PBT and PEF, a polymer blend of PBT, PBF, and PBBf, a polymer blend of PBT, PBF, and PEF, a polymer blend of PBT, PBBf, and PEF, a polymer blend of PBT, PBF, PBBf, and PEF, or any combination thereof.

[0062] In some embodiments, process 400 includes obtaining a composition of materials. For example, the one or more materials include a polymer, such as PBF, PBBf, or a copolymer of BF and BBf (e.g., a copolyester), and other materials (e.g., additives, polymers such as PBT or PEF), and are included in or in the form of a composition. The one or more materials and / or the composition of materials can include any of the materials described with respect to the materials included in the keycaps of the present disclosure.

[0063] In some embodiments, the composition further comprises PEF. In such embodiments, process 400 further comprises mixing the PEF with a polymer, blend, or copolymer of one or more materials to form a blend of the PEF and the polymer, blend, or copolymer of one or more materials, thereby forming a blend of the PEF. The mixing can be performed before extruding the melted composition to produce compounded pellets.

[0064] In some embodiments, obtaining one or more materials or compositions can include heating the one or more materials or compositions for a period of time (e.g., 4 to 8 hours at a temperature in the range of 80 °C to 120 °C). The heating dries the one or more materials or compositions. For example, the moisture level of PBF, PBBf, PEF, or PBT can be less than 0.2%, preferably less than 0.03%.

[0065] In some embodiments, one or more materials or compositions need to be compounded to form pellets suitable for injection molding, as described below with respect to Example VIII. Compounding can include melting the one or more materials, mixing the materials together, and extruding the one or more materials to produce pellets.

[0066] In 404, process 400 includes melting one or more materials or compositions. Melting includes melt - mixing one or more materials or compositions. For example, the melting point of PBT is 221 - 225 °C, the melting point of PBF is 168 - 186 °C, the melting point of PEF is 202 - 220 °C, and the melting point of PBBf is 215 - 217 °C. As described in Example X below, the materials are mixed in a molten state. In one embodiment, compounding PBF and / or PBBf with any of the above additives includes mixing PBF pellets and / or PBBf pellets with the additives in a molten state. In another embodiment, compounding PBF and PBT includes mixing PBF pellets and PBT pellets in a molten state. In another embodiment, compounding PBF and PBT with any of the above additives includes mixing PBF and PBT pellets with the additives in a molten state. In another embodiment, compounding BF and BBf copolymers with any of the above additives includes mixing BF and BBf copolymer pellets with the additives in a molten state. In another embodiment, compounding PBF and PEF with any of the above additives includes mixing PBF and PEF pellets with the additives in a molten state. In another embodiment, compounding BF and EF copolymers with any of the above additives includes mixing BF and EF copolymer pellets with the additives in a molten state. In another embodiment, compounding PBBf and PEF with any of the above additives includes mixing PBBf and PEF pellets with the additives in a molten state. In another embodiment, compounding BBf and EF copolymers with any of the above additives includes mixing BBf and EF copolymer pellets with the additives in a molten state.

[0067] In 406, process 400 includes extruding one or more melted materials or a melted composition to produce compounded pellets. Extrusion refers to a material forming process in which a material is forced to flow (e.g., by pressure) through a die of an extruder (or extruder) to convert the material into a desired shape such as pellets. Extrusion can be used to mix two or more materials by adding the two or more materials to the extruder and flowing them along the extruder. Different materials can be supplied to the extruder separately or as a mixture to form compounded pellets. The extruder may be a single-screw extruder or a twin-screw extruder, and the twin-screw extruder provides better control over the extrusion process. In some embodiments, the compounded pellets formed at 406 are subsequently heated to dry the pellets.

[0068] In some embodiments, one or more materials include PBF and PBT. In such embodiments, process 400 further includes blending PBF with PBT before extruding the melted composition to produce compounded pellets. The blend of PBT and PBF can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBT. The weight percentages of PBT and PBF can be selected to obtain desired properties in the blend, such as a specific melting temperature between those of the pure polymers.

[0069] In some embodiments, one or more materials include PBBf and PBT. In such embodiments, process 400 further includes blending PBBf with PBT before extruding the melted composition to produce compounded pellets. The blend of PBT and PBBf can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBT. The weight percentages of PBBf and PBT can be selected to obtain desired properties in the blend, such as a specific melting temperature between the pure polymers.

[0070] In some embodiments, one or more materials include PBF and PBBf. In such embodiments, process 400 further includes blending PBF with PBBf before extruding the melted composition to produce compounded pellets. The blend of PBF and PBBf can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBF. The weight percentages of PBF and PBBf can be selected to obtain desired properties in the blend, such as their specific melting temperature between the pure polymers.

[0071] In some embodiments, one or more materials include PBF and PEF. In such embodiments, process 400 further includes blending PBF with PEF before extruding the melted composition to produce compounded pellets. The blend of PBF and PEF can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBF. The weight percentages of PBF and PEF can be selected to obtain desired properties in the blend, such as a specific melting temperature between those of the pure polymers.

[0072] In some embodiments, one or more materials include PBBf and PEF. In such embodiments, process 400 further includes blending PBBf with PEF before extruding the melted composition to produce compounded pellets. The blend of PBBf and PEF can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBBf. The weight percentages of PBBf and PEF can be selected to obtain desired properties in the blend, such as a specific melting temperature between those of the pure polymers.

[0073] In some embodiments, the one or more materials include copolymers of any combination of BF, BBf, EF, or BT, and polymers of any combination of PBF, PBBf, PEF, or PBT. In such embodiments, process 400 further includes blending the copolymer with the polymer before extruding the melted composition to produce compounded pellets. The blend of the copolymer and the polymer can include 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt%, or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt%, or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%) of PBF or BF. The weight percentages of the copolyesters of BF, BBf, EF, and / or BT, and the polyesters of PBF, PBBf, PEF, and / or PBT can be selected to obtain desired properties in the blend, such as a specific melting temperature between those of the pure polymers.

[0074] In some embodiments, the composition includes any of the materials described above and one or more additives. The one or more additives can include a first additive selected from, but not limited to, antioxidants, UV stabilizers, flame retardants, hydrolysis inhibitors, coloring pigments, lubricants, waxes, nucleating agents, laser marking additives, and any combination thereof. Alternatively or additionally, the one or more additives can include a second additive. The second additive can include, but is not limited to, reinforcing additives selected from glass fibers, carbon fibers, talc, or any combination thereof. Alternatively or additionally, the second additive can include, but is not limited to, cellulose, bamboo, softwood, hardwood, flax, kenaf, jute, ramie, coir, kapok, sisal, henequen, abaca, hemp, bagasse, straw, rice husk, corn, sunn, and any combination thereof.

[0075] Process 400 further includes injection molding the compounded pellets to form the keycap. The injection molding can be performed using an injection molding machine. An exemplary injection molding machine is shown in FIG. 3. The injection molding includes heating the extruded pellets including one or more materials or compositions to a molten state at 408, and injecting the one or more materials in the molten state into a mold to form the keycap at 410. Process 400 can also include annealing the formed keycap at 60° C. or higher, or 100° C. or higher. For example, the annealing can be performed at 60-135° C. In some embodiments, the annealing is performed at 115° C. Annealing increases the crystallinity of the keycap, thereby improving its strength and durability characteristics.

Example

[0076] <Example I: Injection Molding Procedure and Characteristics of PBF> PBF has a melting temperature of about 168° C. to 186° C. In this example, the PBF resin is injection molded using an injection molding setup (e.g., molding machine 300 in FIG. 3) to form the keycap. The PBF resin is air-dried or vacuum-dried at 80° C. to 120° C. for 4 to 8 hours before injection molding. The moisture level of the environment during drying is less than 0.2%, or less than 0.03%. The PBF pellets are heated to a melt (melt referring to the material in the molten state) at a barrel temperature of the injection molding machine of about 180° C. to 230° C. or about 190° C. to 210° C. before injection. The melt is introduced into a mold maintained at a temperature of 40° C. to 100° C., or 60° C. to 80° C., at an injection pressure of 50 to 180 MPa, or 70 to 120 MPa. The intrinsic viscosity (IV) is 0.5 to 1.5 dL / g, and the melt flow index is 5 g / 10 min to 70 g / 10 min within the selected injection molding temperature and load range.

[0077] The tensile modulus of PBF is in the range of 1 to 4 GPa, or in the range of 2 to 4 GPa, and the maximum tensile strength is in the range of 20 to 70 MPa, or in the range of 40 to 70 MPa. The properties of the PBF sample are further improved by annealing the formed sample at 60 to 135 °C, preferably 115 °C. Annealing increases the crystallinity of the key cap, thereby improving its strength and durability.

[0078] PBF can be synthesized as described by Papageorgiou et al., "Evaluation of polyesters from renewable resources as alternatives to the current fossil-based polymers. Phase transitions of poly(butylene 2,5-furan-dicarboxylate)", Polymer 55, 3846 (2014) (Non-Patent Document 1) or J.C. Morales-Huerta et al., "Poly(alkylene 2,5-furandicarboxylate)s (PEF and PBF) by ring opening", Polymer 87, 148 (2016) (Non-Patent Document 2).

[0079] <Example II: Injection Molding Procedure of PBF Blended with Additives> For actual use, the PBF resin can be blended with various additives (see Example VIII for blending). For example, one or more additives including glass fiber, carbon fiber, talc, or natural filler can be added at 1 to 60 wt% for mechanical reinforcement. Natural filler refers to plant-based filler materials derived from plants (such as grass, shrubs, trees, etc.). Examples of natural fillers include, but are not limited to, cellulose, bamboo, softwood, hardwood, flax, kenaf, jute, ramie, coir, kapok, sisal, henequen, abaca, hemp, bagasse, straw, rice husk, corn, or sunflower.

[0080] In this embodiment, a flame retardant such as phosphoric ether, magnesium hydroxide, or aluminum diethylphosphinate can be added in an amount of 1 to 40% by weight. A sterically hindered phenol or thioether or phosphite or combination can be added as an antioxidant in an amount of 0.1 to 10% by weight. An acid scavenger may be added as a hydrolysis inhibitor in an amount of 0.1 to 10% by weight. Benzotriazole or hydroxybenzophenone may be added as a UV stabilizer in an amount of 0.1 to 10% by weight. A coloring pigment may be added in an amount of 20% by weight or less as needed. The discoloring additive for laser marking can be added in an amount of 0.02% to 5%. Other additives include lubricants such as polytetrafluoroethylene ethylene (PTFE), esters, and metal salts of fatty acids such as zinc stearate, calcium stearate, and adipic acid glycol polyester (AAGP), sodium benzoate, sodium salts of saccharin, boron nitride, organic acids, metal salts, CNTs, talc, glass fibers, or inorganic substances such as metal carbonates, and nucleating agents such as coupling agents, and waxes such as ethylene bisstearamide.

[0081] The compounded PBF composite pellets are injection molded using an injection molding setup (e.g., the molding machine 300 described with respect to FIG. 3) to form a keycap. The PBF composite is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours prior to injection molding. The moisture level during drying is less than 0.2% or less than 0.03%. The PBF pellets are heated to about 180°C to 230°C or 190°C to 210°C and then the melt is injected into a mold maintained at a temperature of 40°C to 100°C or 60°C to 80°C at a pressure of 50 to 220 MPa or a pressure of 90 to 150 MPa. In the selected injection molding temperature and load range, the intrinsic viscosity (IV) is 0.5 to 1.5 dL / g and the melt flow index is 5 g / 10 min to 70 g / 10 min.

[0082] The tensile modulus of the composite of PBF and the reinforcing additive is in the range of 3 to 7 GPa, or in the range of 5 to 7 GPa, and the maximum tensile strength is in the range of 50 to 150 MPa, or in the range of 90 to 150 MPa.

[0083] <Example III: Injection Molding Procedure of PBF / PBT Blend> As described above, PBF has a melting temperature of about 168 °C to 186 °C, and PBT has a melting point of about 221 °C to 225 °C. In applications where a melting temperature higher than that of pure PBF is required, it may therefore be desirable to use a blend of PBF and PBT. The synthesis of such blends is described in the specification of Chinese Patent Application Publication No. 110229480 by X. Zhang et al., "A kind of preparation method of poly-furandicarboxylic acid butanediol ester and polybutylene terephthalate (PBT) blend" (Patent Document 1). The melting point of the blend varies depending on the ratio of PBF to PBT. For example, a 50 / 50 blend of PBF / PBT has a melting temperature close to 195 °C to 200 °C.

[0084] In this example, a blend containing PBF and PBT is injection molded using an injection molding setup as described above (e.g., the molding machine 300 in FIG. 3) to form a keycap. The compounded PBF and PBT pellets are air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours before injection molding. In this example, the moisture level during drying is less than 0.2%, or less than 0.03%. The compounded PBF and PBT pellets are heated to 180 °C to 240 °C or 190 °C to 220 °C and then injection molded into a mold maintained at a temperature of 40 °C to 120 °C or 60 °C to 80 °C at a pressure of 50 to 150 MPa or 70 to 120 MPa.

[0085] In this example, the tensile modulus of the PBF / PBT blend is in the range of 1 to 4 GPa, or in the range of 2 to 4 GPa, and the maximum tensile strength is in the range of 20 to 70 MPa or in the range of 40 to 70 MPa. The load deflection temperature of the blend is expected to be 60 to 150 °C, or 100 to 150 °C.

[0086] <Example IV: Injection Molding Procedure and Characteristics of PBBf> As described above, PBBf has a melting temperature of about 215 °C to 217 °C. In this example, the PBBf resin is injection molded using an injection molding setup (e.g., the injection molding machine 300 in FIG. 3) to form a keycap. The PBBf resin is air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours before injection molding. The moisture level after drying is less than 0.2%, or less than 0.03%. The PBBf pellets are heated to a barrel temperature of about 220 °C to 280 °C, or 230 °C to 260 °C of the injection molding machine before injecting the melt into a mold set at a temperature of 60 °C to 120 °C, or 80 °C to 110 °C, at an injection pressure of 50 to 180 MPa, or at an injection pressure of 70 to 120 MPa. The intrinsic viscosity (IV) is 0.5 to 1.5 dL / g, and the melt flow index is 5 g / 10 min to 70 g / 10 min in the selected injection molding temperature and load range.

[0087] The tensile modulus of PBBf is in the range of 1 to 4 GPa, or in the range of 2 to 4 GPa, and the maximum tensile strength is in the range of 40 to 90 MPa, or in the range of 55 to 90 MPa.

[0088] BFDCA, which is a precursor of PBBf, can be synthesized as described in Mingchun Ye et al., "Oxidative coupling of 2-methyl furoate: A scalable synthesis of dimethyl 2,2’-bifuran-5,5’-dicarboxylate", Applied Catalysis A: General, 619, 118138 (2021) (Non-Patent Document 3), and PBBf can be synthesized from the precursor BFDCA as described in T. Kainulainen et al., "Utilizing Furfural-Based Bifuran Diester as Monomer and Comonomer for High-Performance Bioplastics: Properties of Poly(butylene furanoate), Poly(butylene bifuranoate), and Their Copolyesters", Biomacromolecules 21, 743 (2020) (Non-Patent Document 4).

[0089] <Example V: Injection Molding Procedure of PBBf Blended with Additives> For actual use, the PBBf resin can be compounded with various additives including, but not limited to, glass fiber, carbon fiber, talc, or natural fillers. Such additives can be added in an amount of 1 to 60 wt% for mechanical reinforcement. Flame retardants such as phosphate ether, magnesium hydroxide, or aluminum diethylphosphinate can be added in an amount of 1 to 40 wt%. As antioxidants, sterically hindered phenols or thioethers or phosphites or any combination thereof can be added in an amount of 0.1 to 10 wt%. As a hydrolysis inhibitor, an acid scavenger can be added in an amount of 0.1 to 10 wt%. As a UV stabilizer, benzotriazole or hydroxybenzophenone can be added in an amount of 0.1 to 10 wt%. A coloring pigment can be added in an amount of 20 wt% or less as needed. A discoloring additive for laser marking can be added in an amount of 0.02% to 5%. Other additives as needed: lubricants such as polytetrafluoroethylene ethylene (PTFE), esters, and metal salts of fatty acids such as zinc stearate, calcium stearate, and AAGP, sodium benzoate, sodium salts of saccharin, boron nitride, organic acids, metal salts, inorganic substances such as CNT, talc, glass fiber, or metal carbonate, and nucleating agents such as coupling agents, and waxes such as ethylene bisstearamide may be added.

[0090] In this example, the compounded PBBf composite pellets are injection molded using an injection molding setup (e.g., the molding machine 300 in FIG. 3) to form keycaps. The PBBf composite is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours before injection molding. The moisture level after drying is less than 0.2% or less than 0.03%. The PBBf composite pellets are heated to a temperature of about 220°C to 280°C or a barrel temperature of 230°C to 260°C of the injection molding machine before injecting the melt into a mold set at a temperature of 60°C to 120°C or a temperature of 80°C to 110°C at an injection pressure of 50 to 220 MPa or an injection pressure of 90 to 150 MPa. The intrinsic viscosity (IV) is 0.5 to 1.5 dL / g, and the melt flow index is 5 g / 10 min to 70 g / 10 min in the selected injection molding temperature and load range.

[0091] The tensile modulus of the PBBf-glass fiber composite is in the range of 3 to 7 GPa, or in the range of 5 to 7 GPa, and the maximum tensile strength is in the range of 50 to 150 MPa, or in the range of 90 to 150 MPa.

[0092] <Example VI: Injection Molding Procedure for PBF-PBBf Blend and Copolymer of BF and BBf> As described above, PBF has a melting temperature of about 168°C to 186°C, and PBBf has a melting point of 215°C to 217°C. Therefore, in some applications, it is desirable to blend PBF and PBBf, or to synthesize a random copolymer (e.g., copolyester) of butylene furanoate (BF) and butylene bifuranate (BBf) derived from FDCA and BFDCA, respectively. The synthesis of the random copolymer of BF and BBf is described in Kainulainen et al., "Utilizing Furfural-Based Bifuran Diester as Monomer and Comonomer for High-Performance Bioplastics: Properties of Poly(butylene furanoate), Poly(butylene bifuranoate), and Their Copolymers", Biomacromolecules 21, 743-752 (2020) (Non-Patent Document 4).

[0093] Depending on the weight percentage of BF in the blend or copolymer, the melting temperature can range from 168 °C to 217 °C. In this example, the blend of PBF and PBBf or the copolymer of BF and BBf is injection molded to form a keycap using an injection molding setup (e.g., the molding machine 300 in FIG. 3). The compounded pellets containing the blend of PBF and PBBf or the copolymer of BF and BBf are air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours prior to injection molding. The moisture level during drying is less than 0.2% or less than 0.03%. The blend or copolymer is heated at 180 °C to 280 °C prior to injection molding and placed into a mold maintained at a temperature of 40 °C to 120 °C or 60 °C to 80 °C at a pressure of 50 to 180 MPa or a pressure of 70 to 120 MPa. The tensile modulus of the PBF / PBBf blend or the copolymer of BF and BBf ranges from 1 to 4 GPa or from 2 to 4 GPa, and the maximum tensile strength ranges from 20 to 90 MPa or from 40 to 90 MPa.

[0094] <Example VII: Injection Molding Procedure for a Blend of PBF and PBBf or a Copolymer of BF and BBf Containing Additives> Blends of PBF and PBBf or copolymers of BF and BBf can be compounded with various additives. The additives can include, but are not limited to, glass fibers, carbon fibers, talc, or natural fillers. Such additives can be added in an amount of 1 to 60% by weight for mechanical reinforcement. As flame retardants, flame retardants such as phosphate ethers, magnesium hydroxide, and aluminum diethylphosphinate can be added in an amount of 1 to 40% by weight. Hindered phenols or thioethers or phosphites or combinations can be added as antioxidants in an amount of 0.1 to 10% by weight. Acid scavengers can be added in an amount of 0.1 to 10% by weight as hydrolysis inhibitors. Benzotriazoles and hydroxybenzophenones can be added in an amount of 0.1 to 10% by weight as UV stabilizers. Coloring pigments can be added in an amount of 20% by weight or less as needed. Discoloring additives for laser marking can be added in an amount of 0.02% to 5%. Other additives can be added as needed: lubricants such as polytetrafluoroethylene ethylene (PTFE), esters, and metal salts of fatty acids such as zinc stearate, calcium stearate, and AAGP; inorganic substances such as sodium benzoate, sodium salts of saccharin, boron nitride, organic acids, metal salts, CNT, talc, glass fibers, or metal carbonates; nucleating agents such as coupling agents; and waxes such as ethylene bisstearamide.

[0095] The blended blend of PBF and PBBf or the synthetic copolymer of BF and BBf is injection molded using an injection molding setup (e.g., the molding machine 300 in FIG. 3) to form a key cap. The blend or copolymer-based composite is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours prior to injection molding. In this example, the moisture level during drying is less than 0.2% or less than 0.03%. After heating the blended blend or copolyester pellets containing additives to about 180°C to 280°C, the melt is injected into a mold maintained at a temperature of 40°C to 120°C or 60°C to 110°C at a pressure of 50 to 220 MPa or a pressure of 90 to 150 MPa. In the selected injection molding temperature and load range, the intrinsic viscosity (IV) is 0.5 to 1.5 dL / g and the melt flow index is 5 g / 10 min to 70 g / 10 min. The tensile modulus of the composite of PBF and the reinforcing additive is in the range of 3 to 7 GPa or in the range of 5 to 7 GPa, and the maximum tensile strength is in the range of 50 to 150 MPa or in the range of 90 to 150 MPa.

[0096] <Example VIII: Injection Molding Procedure for PBF-PEF Blend or Copolymer of BF and EF> As described above, PBF has a melting temperature of about 168°C to 186°C, and PEF has a melting temperature of 202°C to 220°C. Thus, in some applications, it is desirable to blend PBF and PEF or synthesize a random copolymer (e.g., copolyester) of butylene furanoate (BF) and ethylene furanoate (EF). Depending on the weight % of BF in the blend or copolymer, the melting temperature can range from 168°C to 220°C. In this example, a blend of PBF and PEF or a copolymer of BF and EF is injection molded using an injection molding setup (e.g., molding machine 300 of FIG. 3) to form a keycap (e.g., as described with respect to FIGS. 1-2C). The compounded pellets containing the blend of PBF and PEF or the copolymer of BF and EF are air dried or vacuum dried at 80°C to 120°C for 4 to 8 hours prior to injection molding. The moisture level during drying is less than 0.2% or less than 0.03%. The blend or copolymer is heated to 180°C to 280°C prior to injection molding and placed into a mold maintained at a temperature of 40°C to 120°C or 60°C to 80°C at a pressure of 50 to 180 MPa or a pressure of 70 to 120 MPa. The tensile modulus of the PBF / PEF blend or the copolymer of BF and BBf ranges from 1 to 4 GPa or from 2 to 4 GPa, and the maximum tensile strength ranges from 20 to 95 MPa or from 40 to 95 MPa.

[0097] <Example IX: Injection Molding Procedure for a Blend of PBF and PEF or a Copolymer of BF and EF Containing Additives> The blend of PBF and PEF or the copolymer of BF and EF can be compounded with various additives. The additives can include, but are not limited to, glass fiber, carbon fiber, talc, or natural fillers. Such additives can be added in an amount of 1 to 60% by weight for mechanical reinforcement. As a flame retardant, a flame retardant such as phosphoric ether, magnesium hydroxide, aluminum diethylphosphinate can be added in an amount of 1 to 40% by weight. A sterically hindered phenol or thioether or phosphite or a combination can be added as an antioxidant in an amount of 0.1 to 10% by weight. An acid scavenger can be added as a hydrolysis inhibitor in an amount of 0.1 to 10% by weight. Benzotriazole or hydroxybenzophenone can be added as a UV stabilizer in an amount of 0.1 to 10% by weight. A coloring pigment may be added in an amount of 20% by weight or less as needed. A discoloring additive for laser marking can be added in an amount of 0.02% to 5%. Other additives may be added as needed: lubricants such as polytetrafluoroethylene ethylene (PTFE), esters, and metal salts of fatty acids such as zinc stearate, calcium stearate, and AAGP, inorganic substances such as sodium benzoate, sodium salts of saccharin, boron nitride, organic acids, metal salts, CNT, talc, or metal carbonates, and nucleating agents such as coupling agents, and waxes such as ethylene bisstearamide.

[0098] The blended mixture of PBF and PEF or the synthetic copolymer of BF and EF is injection molded using an injection molding setup (e.g., the molding machine 300 of FIG. 3) to form a keycap (e.g., those described with respect to FIGS. 1 - 2C). The blend or copolymer - based composite is air - dried or vacuum - dried at 80°C to 120°C for 4 to 8 hours before injection molding. In this example, the moisture level during drying is less than 0.2% or less than 0.03%. After heating the blended mixture or copolyester pellets containing additives to about 180°C to 280°C, the melt is injected into a mold maintained at a temperature of 40°C to 120°C or 60°C to 110°C at a pressure of 50 to 220 MPa or a pressure of 90 to 150 MPa. In the selected injection molding temperature and load range, the intrinsic viscosity (IV) is 0.5 to 1.5 dL / g and the melt flow index is 5 g / 10 min to 70 g / 10 min. The tensile modulus of the composite of PBF and reinforcing additives is in the range of 3 to 7 GPa or in the range of 5 to 7 GPa, and the maximum tensile strength is in the range of 50 to 150 MPa or in the range of 90 to 150 MPa.

[0099] <Example X: Blending of PBF> (Blending of PBF and Additives) As described above, PBF has a melting temperature of about 168°C to 186°C. To improve the durability and processability of PBF for practical applications, PBF can be blended with additives such as antioxidants, UV stabilizers, flame retardants, hydrolysis inhibitors, coloring pigments, lubricants, waxes, nucleating agents, discoloring additives for laser marking, etc. to obtain extrusion pellets.

[0100] In this example, before extrusion, the PBF is air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours. The additive is dried as required. The moisture level during drying is less than 0.2% or less than 0.03%. The PBF pellets and the additive are melt-mixed at 180 °C to 230 °C or 190 °C to 210 °C. The components are fed together or separately along the extruder using the side feeds of the extruder. The extrusion is carried out using a twin-screw or single-screw extruder. Generally, a twin-screw extruder can be more shear-intensive compared to a single-screw extruder. The extruded composition is optionally pelletized and dried to obtain dry pellets for injection molding. The moisture content in the dry pellets is less than 0.2% or less than 0.03%.

[0101] (Compounding of PBF with fillers and / or additives) For practical use, the PBF can be compounded with various fillers and additives as discussed in the above (Example II). In this example, before extrusion, the PBF is air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours. The moisture level during drying is less than 0.2% or less than 0.03%. The PBF pellets and the filler, such as glass fiber, carbon fiber, talc, or natural filler and / or other additives are melt-mixed at 180 °C to 230 °C or 190 °C to 210 °C. The components can be fed together or separately along the extruder. The reinforcing additive is fed separately using a side feeder to avoid wear of the reinforcing additive. In a low-shear single-screw extruder, the filler or additive is mixed with the polymer and fed together through the main feeder of the extruder. In a high-shear twin-screw extruder, the filler or additive can be mixed with the polymer or fed separately through the main side feeder of the extruder. The extrusion is carried out using a twin-screw or single-screw extruder. The extruded composition is optionally pelletized and dried to obtain dry pellets for injection molding. The moisture content in the dry pellets is less than 0.2%, preferably less than 0.03%.

[0102] (Formulation of Blend of PBF and PBT) In this example, before extrusion, PBF is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. Before extrusion, PBT is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. The moisture level during drying in both PBF and PBT is less than 0.2% or 0.03%. PBF and PBT pellets as well as additives are melt-mixed in an extruder. PBF and PBT are fed together into the extruder and melt-mixed under shear to obtain a PBT / PBF blend. The amount of PBT varies in the range of 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt%, or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt%, or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt%, or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt%, or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt%, or 90 to 99 wt%). The extruder temperature ranges from 180°C to 250°C, and the extruder temperature is determined by the melting temperature of the PBF / PBT blend, which depends on the PBF / PBT mixing ratio. Extrusion is carried out using a twin-screw or single-screw extruder. The extruder screw speed is 30 to 200 rpm, or 100 rpm or less. The extruded composition is optionally pelletized to obtain dry pellets for injection molding and air-dried or vacuum-dried. The moisture content in the dry pellets is less than 0.2% or less than 0.03%.

[0103] (Formulation of PBBf and Additives) As mentioned above, PBBf has a melting temperature of about 215°C to 217°C. To improve the durability and processing of PBBf for practical applications, PBBf can be blended with additives such as antioxidants, UV stabilizers, flame retardants, hydrolysis inhibitors, coloring pigments, lubricants, waxes, nucleating agents, discoloring additives for laser marking, etc. to obtain extrusion pellets.

[0104] In this example, before extrusion, the PBBf is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. The additive is dried as required. The moisture level during drying is less than 0.2% or less than 0.03%. The PBBf pellets and the additive are melt-mixed at 220°C to 280°C or 230°C to 260°C. The mixture is fed together along the extruder. Alternatively, the PBBf pellets and the additive are fed separately along the extruder. The extrusion is carried out using a twin-screw or single-screw extruder. The screw speed of the extruder varies from 30 to 200 rpm or 100 rpm or less. The extruded composition is optionally pelletized and air-dried or vacuum-dried to obtain dry pellets for injection molding. The moisture content in the dry pellets is less than 0.2% or less than 0.03%.

[0105] (Blending of PBBf with fillers and / or additives) For actual use, the PBBf can be blended with various fillers and additives as discussed in Example V above. In this example, before extrusion, the PBBf is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. The moisture level during drying is less than 0.2% or less than 0.03%. The PBBf pellets and the filler, such as glass fiber, carbon fiber, talc, or natural filler and / or other additives are melt-mixed at 220°C to 280°C or 230°C to 260°C. The components are fed together or separately along the extruder. Preferably, the filler is fed partially separately using a side feeder. The extrusion is carried out using a twin-screw or single-screw extruder. The extruded composition is optionally pelletized and dried to obtain pellets for injection molding. The moisture content in the dry pellets is less than 0.2%, preferably less than 0.03%.

[0106] (Blend of PBF and PBBf) In this example, before extrusion, PBF and PBBf are air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours. The moisture level during drying in both PBF and PBBf is less than 0.2% or less than 0.03%. PBF, PBBf, and the additive are fed together in an extruder and melt-mixed under shear to obtain a PBF / PBBf blend. Fillers and / or additives such as glass fiber, carbon fiber, talc, or natural fillers are added together with PBF and PBBf or separately along the extruder. The amount of PBF varies in the range of 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt% or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt% or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt% or 90 to 99 wt%). The composition of the filler varies in the range of 1 to 60 wt%. The extruder temperature ranges from 180 °C to 280 °C, and the preferred extruder temperature is determined by and set slightly higher than the melting temperature of the PBF / BBf blend, which depends on the PBF / BBf mixing ratio or BF to BBf ratio in the BF / BBf copolyester. Extrusion is carried out using a twin-screw or single-screw extruder. The screw speed of the extruder varies from 30 to 200 rpm or 100 rpm or less. The extruded composition is optionally pelletized and dried to obtain dried pellets for injection molding. The moisture content in the dried pellets is less than 0.2%, preferably less than 0.03%.

[0107] (Formulation of PBF / PBBf Blend or Copolymer of BF and BBf with Additive) The PBF / PBBf blend or the copolymer of BF and BBf can be compounded with various additives (e.g., fillers) as discussed in Examples II and V above. In this example, before extrusion, the PBF, PBBf, or the copolymer of BF and BBf is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. The moisture level during drying is less than 0.2% or less than 0.03%. The polymer, copolymer, and / or one or more fillers such as glass fiber, carbon fiber, talc, natural fillers, and / or other additives are melt-mixed at 180°C to 280°C, and the preferred extruder temperature is determined by and set slightly higher than the melting temperature of the PBF / PBBf blend that depends on the PBF / BBf mixing ratio or the BF to BBf ratio in the BF / BBf copolyester. The components are fed together or separately along the extruder. Preferably, the filler is fed separately using a side feeder. The extrusion is carried out using a twin-screw or single-screw extruder. The screw speed of the extruder varies from 30 to 200 rpm or 100 rpm or less. The extruded composition is optionally pelletized and dried to obtain dry pellets for injection molding. The moisture content in the dry pellets is less than 0.2% or less than 0.03%.

[0108] (Blend of PBF and PEF) In this example, before extrusion, PBF and PEF are air-dried or vacuum-dried at 80 °C to 120 °C for 4 to 8 hours. The moisture level during drying in both PBF and PEF is less than 0.2% or less than 0.03%. PBF, PEF, and the additive are fed together into an extruder and melt-mixed under shear to obtain a PBF / PEF blend. Fillers and / or additives such as glass fiber, carbon fiber, talc, or natural fillers are added together with PBF and PEF or separately along the extruder. The amount of PBF varies in the range of 1 to 99 wt%, or 1 to 20 wt% (e.g., 1 to 10 wt% or 10 to 20 wt%), or 20 to 40 wt% (e.g., 20 to 30 wt% or 30 to 40 wt%), or 40 to 60 wt% (e.g., 40 to 50 wt% or 50 to 60 wt%), or 60 to 80 wt% (e.g., 60 to 70 wt% or 70 to 80 wt%), or 80 to 99 wt% (80 to 90 wt% or 90 to 99 wt%). The composition of the filler varies in the range of 1 to 60 wt%. The extruder temperature ranges from 180 °C to 280 °C, and the preferred extruder temperature is determined by the melting temperature of the PBF / PEF blend and set slightly higher than that. Extrusion is carried out using a twin-screw or single-screw extruder. The screw speed of the extruder varies from 30 to 200 rpm or 100 rpm or less. The extruded composition is optionally pelletized and dried to obtain dried pellets for injection molding. The moisture content in the dried pellets is less than 0.2%, preferably less than 0.03%.

[0109] (Formulation of PBF / PEF blend or copolymer of BF and EF with additive) The PBF / PEF blend or the copolymer of BF and EF can be compounded with various additives (e.g., fillers) as discussed in Examples (VIII) and (IX) above. In this example, before extrusion, the PBF, PEF, or the copolymer of BF and EF is air-dried or vacuum-dried at 80°C to 120°C for 4 to 8 hours. The moisture level during drying is less than 0.2% or less than 0.03%. The polymer, copolymer, and / or one or more fillers such as glass fiber, carbon fiber, talc, natural fillers, and / or other additives are melt-mixed at 180°C to 280°C, and the preferred extruder temperature is determined by and set slightly higher than the melting temperature of the PBF / PBBf blend that depends on the PBF / PEF mixing ratio or BF to EF ratio in the BF / EF copolymer. The components are fed together or separately along the extruder. Preferably, the filler is fed separately using a side feeder. Extrusion is performed using a twin-screw or single-screw extruder. The screw speed of the extruder varies from 30 to 200 rpm or 100 rpm or less. The extruded composition is optionally pelletized and dried to obtain dry pellets for injection molding. The moisture content in the dry pellets is less than 0.2% or less than 0.03%.

[0110] (Remarks) The above description and drawings are illustrative and should not be construed as limiting. Numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, well-known details may not be described in order to avoid obscuring the description. Furthermore, various modifications can be made without departing from the scope of the embodiments.

[0111] The terms used herein generally have the ordinary meaning in the context of the present disclosure and in the particular context in which each term is used. It is understood that the same thing can be said in multiple ways. For example, "resin" is a form of "polymer", and it is recognized that these terms can be used interchangeably in some cases.

[0112] Unless otherwise stated, the term "about" generally means an inclusion of a variation or range of ± 10%.

[0113] The use of examples anywhere in this specification, including examples of any terms discussed herein, is merely illustrative and is not intended to further limit the scope or meaning of the disclosure or of any illustrative terms. Similarly, the disclosure is not limited to the various embodiments given in this specification.

Claims

1. A polymer of butylene 2,5-furandicarboxylate (PBF), A polymer of butylene bifulanoate (PBBf), A copolymer of (i) butylene 2,5-furandicarboxylate (BF) and (ii) butylene bifulanoate (BBf), A copolymer of (i) ethylene 2,5-furandicarboxylate (EF) and (ii) one or both of BF and BBf, and A copolymer of (i) butylene terephthalate (BT) and (ii) one or more of BF, BBf, and EF A keycap comprising one or more materials selected from the group consisting of: The keycap is configured to be attached to the upper part of the switching mechanism of the key of the keyboard.

2. The keycap according to claim 1, comprising PBF.

3. The keycap according to claim 1, comprising PBBf.

4. A blend of PBF and PBBf, or A copolymer of BF and BBf The keycap according to claim 1, comprising.

5. The keycap according to claim 1, further comprising poly(butylene terephthalate) (PBT).

6. A blend of PBT and PBF, A blend of PBT and PBBf, or A copolymer of BT and BF, a copolymer of BT and BBf, or a copolymer of BT, BF, and BBf The keycap according to claim 1, comprising.

7. The keycap according to claim 1, further comprising poly(ethylene 2,5-furandicarboxylate) (PEF).

8. A blend of PEF and PBF, A blend of PEF and PBBf, or A copolymer of EF and BF, a copolymer of EF and BBf, or a copolymer of EF, BF, and BBf The keycap according to claim 7, comprising.

9. The keycap according to claim 1, further comprising an additive selected from the group consisting of an antioxidant, an ultraviolet (UV) stabilizer, a flame retardant, a hydrolysis inhibitor, a coloring pigment, a discoloration additive for laser marking, a lubricant, a wax, a nucleating agent, and any combination thereof.

10. The keycap according to claim 1, further comprising a reinforcing additive selected from the group consisting of glass fiber, carbon fiber, talc, cellulose, bamboo, softwood, hardwood, linen, kenaf, jute, ramie, coir, kapok, sisal, henequen, abaca, hemp, bagasse, wheat straw, rice husk, corn, sunflower, and any combination thereof.

11. The key cap according to claim 10, comprising 1 to 60% by weight of the reinforcing additive.

12. A method for injection molding a key cap, comprising: a polymer of butylene 2,5-furandicarboxylate (PBF), a polymer of butylene bifuranate (PBBf), (i) a copolymer of butylene 2,5-furandicarboxylate (BF) and (ii) butylene bifuranate (BBf), (i) a copolymer of ethylene 2,5-furandicarboxylate (EF) and (ii) one or both of BF and BBf, (i) a copolymer of butylene terephthalate (BT) and (ii) one or more of BF, BBf, and EF, or any combination thereof obtaining one or more materials comprising; heating the one or more materials to a molten state; injecting the one or more materials into a mold to form the key cap. A method comprising the steps of:

13. The method according to claim 12, wherein the one or more materials comprise a blend of PBF and PBBf, or a copolymer of BF and BBf. The method according to claim 12, comprising:

14. The method according to claim 12, wherein the one or more materials further comprise poly(butylene terephthalate) (PBT).

15. The method according to claim 12, wherein the one or more materials comprise a blend of PBT and PBF, a blend of PBT and PBBf, or a copolymer of BT and BF, a copolymer of BT and BBf, or a copolymer of BT, BF, and BBf. The method according to claim 12, comprising:

16. The method according to claim 12, wherein the one or more materials further comprise poly(ethylene 2,5-furandicarboxylate) (PEF).

17. The method according to claim 12, wherein the one or more materials comprise a blend of PEF and PBF, a blend of PEF and PBBf, or a copolymer of EF and BF, a copolymer of EF and BBf, or a copolymer of EF, BF, and BBf. The method according to claim 12, comprising:

18. The method according to claim 12, wherein the one or more materials comprise a blend of PBT and PEF, a copolymer of BT and EF, or a copolymer of BT, EF, and BF, a copolymer of BT, EF, and BBf, or a copolymer of BT, EF, BF, and BBf. The method according to claim 12, comprising:

19. The method according to any one of claims 12 to 18, wherein the one or more materials further comprise an antioxidant, an ultraviolet (UV) stabilizer, a flame retardant, a hydrolysis inhibitor, a coloring pigment, a discoloration additive for laser engraving, a lubricant, a wax, a nucleating agent, or an additive corresponding to any combination thereof.

20. The method according to any one of claims 12 to 18, wherein the one or more materials further comprise a reinforcing additive selected from the group consisting of glass fiber, carbon fiber, talc, cellulose, bamboo, softwood, hardwood, flax, kenaf, jute, ramie, coir, kapok, sisal, henequen, abaca, hemp, bagasse, wheat straw, rice husk, corn, sunn, and any combination thereof.

21. Before heating the one or more materials to a molten state, a step of melting a PBF, a PBBf, a blend of PBF and PBBf, or a copolymer of BF and Bbf; a step of extruding the melted PBF, PBBf, blend of PBF and PBBf, or copolymer of BF and Bbf to produce compounded pellets The method according to any one of claims 12 to 20, further comprising.

22. The method according to any one of claims 12 to 20, further comprising a step of annealing the formed keycap at 60 °C or higher, thereby increasing the crystallinity of the keycap.

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