TWI834923B - Polylactic acid resin composition and application thereof - Google Patents

Abstract

A polylactic acid resin composition includes a polylactic acid resin, a carbon fiber, a carbon black, a nucleating agent and a coupling agent. The content of the polylactic acid resin ranges between 75-95 wt%. The content of the carbon fiber ranges between 2-9 wt%. The content of the carbon black ranges between 0-9 wt%. The content of the nucleating agent ranges between 0.001-5 wt%. The content of the coupling agent ranges between 0.001-5 wt%. The total weight percentage of components (a), (b), (c), (d) and (e) is defined as 100wt%.

Description

Polylactic acid resin composition and its application

The present invention relates to a biodegradable polylactic acid resin composition and its application, in particular to an electronic component tray containing the above polylactic acid resin composition.

In recent years, in view of global warming issues, plastics made from natural plants are attracting attention. Polylactic Acid (PLA) resin is biodegradable and can be obtained from renewable resources such as corn starch, making it an environmentally friendly polymer. However, it is recognized that PLA resin has poor physical properties, such as low heat resistance, poor surface resistance and poor mechanical properties. On the other hand, PLA resin exhibits low crystallization rate and low crystallinity, so that products formed from PLA may not have sufficient heat deflection temperature (HDT) and impact strength. Therefore, it is difficult to use PLA resin as antistatic material and/or industrial pallets.

Electronic component trays, such as integrated circuit (IC) trays, can be used to accommodate, handle and transport IC packages. For a suitable IC pallet for use in manufacturing processes such as resoldering and IC shipping, several specific properties are required, such as HDT, impact strength and surface resistance values, among other properties. Currently, there is still a need for an environmentally friendly IC tray with desired properties. Typical IC trays are mainly made of polyphenylene ether (PPE), which is a petrochemical product and is not biodegradable in normal environments. PPE IC pallets can release greenhouse gases and cause damage to the environment after burning. Therefore, there is a need for an environmentally friendly IC tray with high HDT, high impact strength and low surface resistance.

In some embodiments, the present invention provides a polylactic acid resin composition, which includes polylactic acid resin, carbon fiber, carbon black, nucleating agent and coupling agent. Among them, (a) the polylactic acid resin content is between 75-95wt%; (b) the carbon fiber content is between 2-9wt%; (c) the carbon black content is between 0-9wt%; (d) the nucleating agent content is between 0.001-5wt%; and (e) the coupling agent content is between 0.001-5wt%, wherein the content is based on the total weight of components (a), (b), (c), (d) and (e) being 100wt % calculation.

In some embodiments, the present invention further provides a tray for electronic parts, which includes polylactic acid resin, carbon fiber, carbon black, nucleating agent and coupling agent. Among them, (a) the polylactic acid resin content is between 75-95wt%; (b) the carbon fiber content is between 2-9wt%; (c) the carbon black content is between 0-6wt%; (d) the nucleating agent content is between 0.001-5wt%; and (e) the coupling agent content is between 0.001-5wt%, wherein the content is based on the total weight of components (a), (b), (c), (d) and (e) being 100wt % calculation.

[polylactic acid]

In some embodiments of the present invention, polylactic acid (PLA) may be a homopolymer of lactic acid. Lactic acid exists in optical isomers, namely L-lactic acid (L-form) and D-lactic acid (D-form). For some embodiments of the present invention, PLA can be prepared from one or both of these optical isomers. For the purpose of obtaining PLA with high melting temperature (T _m ) and high glass transition temperature (T _g ), it is desirable to use one of these optical isomers as the main component. For example, in PLA, the content of the L-form of lactic acid may be no less than about 80 mol% or no more than about 20 mol%; such as in PLA, the content of the L-form of lactic acid may be no less than about 85 mol% or no more than about 20 mol%. About 16 mol%; or, such as in PLA, the content of the L-form of lactic acid may be no less than about 90 mol% or no more than about 12 mol%, with the remainder corresponding to or including the D-form of lactic acid.

In other embodiments of the invention, PLA may be a copolymer of lactic acid and a hydroxycarboxylic acid component other than lactic acid. The hydroxycarboxylic acid component other than lactic acid may be, for example, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid or hydroxyheptanoic acid.

PLA can be formed by a polycondensation method using the above-mentioned monomers, or by a ring-opening polymerization method using the corresponding cyclic dimers or compounds of the above-mentioned monomers (such as lactide, which is a cyclic dimer of lactic acid).

In some embodiments of the present invention, the weight average molecular weight ( _Mw ) of PLA may be at least any one of the following: about 10,000 g/mol, about 20,000 g/mol, about 30,000 g/mol, about 40,000 g/mol. mol and about 50,000 g/mol; and may be up to any of the following: about 160,000 g/mol, about 200,000 g/mol, about 250,000 g/mol, about 300,000 g/mol, about 400,000 g/mol, and about 500,000 g/mol. For example, PLA may have a weight average molecular weight of about 30,000 g/mol to about 250,000 g/mol.

In some embodiments of the present invention, based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the content of polylactic acid resin is between 75-95wt%. For example, the content of polylactic acid resin may be 75, 77, 80, 83, 85, 87, 89, 90, 92, 93, 94 or 95 wt%. [nucleating agent]

In some embodiments, nucleating agents can be used to improve the nucleation arrangement of PLA crystals and increase the crystallization rate and crystallinity of PLA. Increasing the crystallization rate and crystallinity of PLA can increase HDT and impact strength. In some embodiments of the present invention, a nucleating agent that can increase the crystallization rate and crystallinity of PLA can be used in the resin composition. In some embodiments, the nucleating agent includes metal carbonates (eg, alkaline earth metal carbonates such as calcium carbonate or barium carbonate), ester derivatives of citric acid (eg, acetyltributyl citrate), metal silicates (e.g. hydrated magnesium silicate, such as talc), amino acids (e.g. glycine or L-alanine), poly(amino acids) (e.g. polyglycine), heterocyclic organic compounds (e.g. N-amino Phthalamide), metal oxides (such as titanium dioxide), or a combination of two or more thereof. In some embodiments, the nucleating agent is L-alanine.

In some embodiments of the present invention, based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the content of the nucleating agent is between 0.001-5wt%. For example, the nucleating agent may be present in an amount of 0.001, 0.005, 0.1, 0.5, 1, 1.5, 2, 3, 4 or 5 wt%. [filler]

Fillers may be added to resin compositions for a variety of purposes, such as reducing costs, improving mechanical strength, or adjusting the appearance of the final product. Different fillers are chosen for different purposes. It has been found that some fillers may be beneficial for one property of the resin composition but may be detrimental for another property of the resin composition. In addition, the addition of fillers such as rubber and plasticizers may adversely affect the thermal stability of the resin composition.

In some embodiments of the present invention, fillers suitable for the PLA resin composition of the present invention include inorganic fillers. Inorganic fillers may include carbonaceous fillers. Carbon-containing fillers include carbon fiber, carbon black or other suitable materials.

Carbon fiber is a high-strength reinforcing material that can increase the impact strength of the PLA resin composition and reduce the surface resistance of the PLA resin composition. Through the combination of nucleating agent and carbon fiber, a synergistic effect can be produced to improve the impact strength properties of the biodegradable PLA resin composition. In addition, since PLA is an organic polymer material, its conductivity is poor. It is easy to cause static electricity accumulation problems. In some embodiments of the present invention, adding carbon fiber to PLA can increase the conductivity of PLA, thereby achieving antistatic effect (for example, surface resistance value <10 ¹² ohm/sq).

In some embodiments of the present invention, based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the content of carbon fiber is less than 10wt%, for example, it can be between 2 -9wt%. For example, the carbon fiber content may be 2, 3, 4, 5, 6, 7, 8 or 9 wt%. In some embodiments of the present invention, it is found that increasing the content of carbon fiber can reduce the surface resistance value; however, when the content of carbon fiber is greater than or equal to 10wt%, although the surface resistance value can be reduced to below 10 ¹² ohm/sq, however, PLA resin The carbon fiber in the composition may be released, which may easily cause defects such as cracks on the surface of the molded product.

Carbon fibers with a variety of suitable lengths and/or particle sizes can be used. In some embodiments, the carbon fibers have a length (eg, average length) of about 0.01 mm to about 800 mm, such as about 0.01 mm, about 1 mm, about 10 mm, about 50 mm, about 100 mm, about 200 mm, about 300 mm. mm, approximately 400 mm, approximately 500 mm, approximately 600 mm, approximately 700 mm or approximately 800 mm. In some embodiments, the carbon fiber has a particle size (eg, average particle size) of about 0.01 μm to about 100 μm, such as about 0.01 μm, about 1 μm, about 10 μm, about 20 μm, about 30 μm, about 40 μm, About 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, or about 100 μm.

In some embodiments of the present invention, carbon black may be added as needed. Carbon black can reduce the surface resistance value of the PLA resin composition, and is cheaper than carbon fiber.

In some embodiments of the present invention, it was found that when carbon black is used alone, the effect is not as good as when the same amount of carbon fiber is used alone, and the HDT, surface resistance value and mechanical strength of the resulting molded article are poor. However, in some embodiments, it is found that when carbon black and carbon fiber are used together, the two can play a synergistic effect and can reduce the surface resistance value to below 10 ¹² ohm/sq without causing cracks on the surface of the molded product. In some embodiments, the surface resistance value can even be further reduced to below 10 ¹⁰ ohm/sq without causing cracks on the surface of the molded product. In some embodiments of the present invention, the PLA resin composition of the present invention may optionally contain carbon black, wherein the total weight of components (a), (b), (c), (d) and (e) is 100wt% Calculated, the content of carbon black is less than 10wt%, for example, it can be between 0-9wt%. For example, the carbon black content may be 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9 wt%. In other embodiments of the present invention, based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the content of carbon black is less than 7wt%, for example, it can be At 0-6wt%, it helps to increase the impact strength to about 1.5 kg-cm/cm or higher and maintain the surface resistance value below 10 ¹² ohm/sq. In some embodiments, the PLA resin composition includes both carbon fiber and carbon black, and based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the carbon fiber and carbon black are The total content of carbon black is less than 15 wt%, for example, less than or equal to 14 wt%, less than or equal to 13 wt%, less than or equal to 12 wt%.

Carbon blacks having a variety of suitable lengths and/or particle sizes can be used. In some embodiments, the carbon black has a length (eg, average length) of about 0.01 mm to about 800 mm, such as about 0.01 mm, about 1 mm, about 10 mm, about 50 mm, about 100 mm, about 200 mm, about 300 mm, approximately 400 mm, approximately 500 mm, approximately 600 mm, approximately 700 mm or approximately 800 mm. In some embodiments, the carbon fiber has a particle size (eg, average particle size) of about 0.01 μm to about 100 μm, such as about 0.01 μm, about 1 μm, about 10 μm, about 20 μm, about 30 μm, about 40 μm, About 50 μm, about 60 μm, about 70 μm, about 80 μm, about 90 μm, or about 100 μm. [Coupling agent]

In the PLA resin composition of some embodiments of the present invention, PLA is an organic material, and the filler is an inorganic material. Unlike organic materials that can form bonds with each other through functional groups, inorganic materials usually do not form strong bonds with organic materials. As a result, the compatibility and adhesion between PLA and inorganic fillers may be poor. In order to solve this problem, a coupling agent can be used to modify the surface of the inorganic filler, and the inorganic filler can be bonded to the organic material through the dual reactivity of the coupling agent. Coupling agents can also be used in organic fillers to further improve the compatibility and adhesion between PLA and organic fillers. In some embodiments, the filler is bonded (eg, covalently bonded) to the PLA via a coupling agent.

The coupling agent may be a silane coupling agent, a titanate coupling agent, or a combination thereof. A variety of suitable silane coupling agents and titanate coupling agents are available. Examples of silane coupling agents suitable for use in some embodiments of the present invention include, but are not limited to: trimethoxysilane, triethoxysilane, or combinations thereof. According to some embodiments of the present invention, the silane coupling agent may be 3-acryloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or a combination thereof. Examples of titanate coupling agents suitable for use in some embodiments of the present invention include, but are not limited to: titanium di(cumylphenylate) oxyacetate, di(dioctyl phosphate) di(dioctylphosphato) ethylene titanate) or a combination thereof.

The coupling agent can be added to the PLA resin composition in different appropriate amounts and can be adjusted depending on the filler content. In some embodiments, based on the total weight of components (a), (b), (c), (d) and (e) being 100wt%, the content of the coupling agent ranges from 0.001 to 5wt%. For example, the coupling agent may be present in an amount of 0.001, 0.005, 0.1, 0.5, 1, 1.5, 2, 3, 4 or 5 wt%. [Polylactic acid resin composition]

In some embodiments of the present invention, the PLA resin composition can be prepared by a variety of appropriate methods. In some embodiments, a PLA resin composition is prepared by (1) mixing a PLA resin with a nucleating agent to form a first mixture, (2) mixing a filler and a coupling agent to form a second mixture, and (3) ) Add the second mixture to the first mixture (or otherwise mix the first mixture with the second mixture) to prepare a PLA resin composition.

The PLA resin composition can be used as an antistatic material. When the PLA resin composition is used as an antistatic material, a slight sacrifice in impact strength can be tolerated, focusing on the improvement of surface resistance. For example, if the surface resistance of an antistatic material is less than 10 ¹² ohm/sq and the impact strength is greater than 1.3 kg-cm/cm, it can be evaluated as an excellent antistatic material.

The PLA resin composition can be further processed into final products, such as covers for electronic products (eg, mobile phones or computers), food containers or trays, or trays for industrial components. In some embodiments, the PLA resin composition may be kneaded by a twin-screw extruder and then injected using an injection molding machine at a temperature ranging from about 150°C to about 200°C to form a tray. The tray can be further baked to relieve stress and stabilize the tray size.

The product made from the PLA resin composition of some embodiments of the present invention is biodegradable, so that the product can be decomposed in the natural environment, such as by microorganisms. In some embodiments, the decomposition degree of the PLA resin composition in a natural environment within about 90 days may be about 70 wt% or higher.

In some embodiments, the PLA resin composition is processed into a biodegradable antistatic material. In other embodiments, the biodegradable antistatic material has a degree of decomposition in the natural environment of about 70 wt% or greater after about 90 days. In other embodiments, the biodegradable antistatic material has an impact strength of about 1.3 kg-cm/cm or higher (e.g., about 1.4 kg-cm/cm or higher, about 1.5 kg-cm/cm or higher). high); HDT is about 125°C or higher (e.g., about 128°C or higher, about 130°C or higher, about 130°C or higher, about 135°C or higher); and the surface resistance value is about 10 ¹² ohm/sq or less (for example, about 10 ¹¹ ohm/sq or less, about 10 ¹⁰ ohm/sq or less, about 10 ⁹ ohm/sq or less, about 10 ⁸ ohm/sq or less, About 10 ⁷ ohm/sq or less, about 10 ⁶ ohm/sq or less, about 10 ⁵ ohm/sq or less, or about 10 ⁴ ohm/sq or less, and can be as low as about 10 ³ ohm/ sq. or smaller). Furthermore, in some embodiments, the surface of the resulting antistatic material has no or only some microcracks.

In some embodiments, the PLA resin composition can be processed into pallets. In other embodiments, the impact strength of the pallet is about 1.5 kg-cm/cm or higher; the HDT is about 125°C or higher (e.g., about 128°C or higher, about 130°C or higher, about 133°C or higher, about 135°C or higher); and the surface resistance value is about 10 ¹² ohm/sq or less (for example, about 10 ¹¹ ohm/sq or less, about 10 ¹⁰ ohm/sq or less, about 10 ⁹ ohm/sq or less, about 10 ⁸ ohm/sq or less, about 10 ⁷ ohm/sq or less, about 10 ⁶ ohm/sq or less, about 10 ⁵ ohm/sq or less or about 10 ⁴ ohm/sq or less, and can be as low as about 10 ³ ohm/sq or less). Trays, such as IC trays suitable for the electronics industry, are specified with high HDT, high impact strength and low surface resistance values (e.g. HDT of approximately 125°C or higher, impact strength of approximately 1.5 kg-cm/cm or higher and surface Resistance value is approximately 10 ¹² ohm/sq or less). Furthermore, in some embodiments, the resulting tray surface has no or only some microcracks. Example

Some embodiments of the present invention are further explained with reference to the following examples and comparative examples; however, these embodiments do not limit the scope of the present invention. In the example, polylactic acid (NatureWorks® 4032D), L-alanine (Merck), carbon fiber (TAIRYFIL® CS-2516), carbon black (CABOT® XC-72) and coupling agent (ShinEtsu KBM-503) are used. The relative amounts of each component are described in Tables 1 and 2.

Mix PLA and L-alanine uniformly to prepare a first mixture. Carbon fibers and/or carbon black are mixed with a coupling agent to prepare a second mixture. The second mixture is added to the first mixture to prepare a PLA composition. The PLA resin composition is kneaded by a twin-screw extruder in a temperature range of about 160°C to about 195°C, and then injection molded using an injection molding machine in a temperature range of about 150°C to about 200°C.

The properties of each injection-molded PLA resin composition were tested according to the ASTM methods described in Tables 3 and 4, and the results were recorded in Tables 3 and 4. Regarding the appearance evaluation of each injection-molded PLA resin composition, if there were obvious cracks in the appearance, it was evaluated as poor (X), and if there were no obvious cracks, it was evaluated as good (O). The appearance evaluation is described in Table 5.

Table 1 Element Example 1 Example 2 Example 3 Example 4 Example 5 (a) polylactic acid 90 88 86 84 91 (b) L-Alanine 1 1 1 1 1 (c) Carbon fiber (CF) 5 5 5 5 5 (d) Carbon black (CB) 1 3 5 7 - (e) Coupling agent 3 3 3 3 3 Table 2 Element Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 (a) polylactic acid 96 86 81 93 91 86 81.5 (b) L-Alanine 1 1 1 1 1 1 1.2 (c) Carbon fiber(CF) - 10 15 - - - 12.2 (d) Carbon black (CB) - - - 3 5 10 4 (e) Coupling agent 3 3 3 3 3 3 1 table 3 method nature unit Example 1 Example 2 Example 3 Example 4 Example 5 ASTM D-638 tensile strength kg/cm ² 586 603 575 505 580 ASTM D-638 Elongation % 1.23 1.31 1.18 1.01 1.21 ASTM D-256 Impact strength kg-cm/cm 1.54 1.64 1.5 1.34 1.52 ASTM D-638 Flexural strength kg/cm ² 902 987 884 805 890 ASTM D-638 Flexural modulus kg/cm ² 89395 91412 87854 74289 88320 ASTM D-257 Surface resistance ohm/sq 1.76E+11 7.94E+09 2.54E +4 152.32 9.89E+11 ASTM D-648 HDT ℃ 133 134 134 135 133 Table 4 method nature unit Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 ASTM D-638 tensile strength kg/cm ² 121 668 710 460 432 353 830 ASTM D-638 Elongation % 3.33 0.98 0.73 3.32 2.98 2.35 0.86 ASTM D-256 Impact strength kg-cm/cm 1.42 1.61 1.73 1.44 1.4 1.31 1.95 ASTM D-638 Flexural strength kg/cm ² 686 1164 1268 695 636 588 1317 ASTM D-638 Flexural modulus kg/cm ² 60856 106542 121452 62174 58472 56934 108200 ASTM D-257 Surface resistance ohm/sq 3.24E+13 1.04E+4 291.68 1.12E+13 5.24 E+12 4.36 E+10 47000 ASTM D-648 HDT ℃ 130 138 142 130 123 111 137.9 table 5 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Appearance evaluation O O O O O O X X O O X X

It can be seen from Example 5 and Comparative Example 1 that adding carbon fiber can help improve the mechanical strength and HDT, reduce the surface resistance value, and improve the antistatic properties. It can be seen from Comparative Examples 1 and 4 to 6 that although adding carbon black can reduce the surface resistance value, the effect is not as good as that of carbon fiber, and in some examples it can be observed that the mechanical strength becomes worse and the HDT also becomes worse. In addition, it was also found that when the carbon fiber or carbon black content of the PLA composition is too high, the appearance of the injection molded product of the PLA composition is prone to obvious cracks, which reduces its commercial use. For example, the carbon fiber content of Comparative Examples 2, 3, and 7 is greater than or equal to 10 parts by weight, the uniformity is poor, and the appearance of the PLA injection molded product is uneven, or even cracked, and is evaluated as poor; Comparative Example 6 contains too much carbon black (10 parts by weight or more), carbon black will float out of the molded article and accumulate on the surface, resulting in poor appearance evaluation.

In Examples 1 to 4, carbon black was added in addition to carbon fiber. The results show that when carbon black and carbon fiber are used together, the two can play a synergistic effect and can reduce the surface resistance value to below 10 ¹² ohm/sq (or even further reduce it to 10 ¹⁰ ohm). /sq or less) and will not cause cracks on the surface of the molded product; in addition, the molded product has excellent mechanical strength and HDT. As mentioned above, although Comparative Examples 2, 3, and 7 can reduce the surface resistance value to less than 10 ¹⁰ ohm/sq, however, cracks occur on the surface due to the excessive carbon fiber content. On the contrary, Examples 3 and 4 of this case have comparable surface resistance. Resistance value, but can maintain less or no surface cracks, and can use less total content of carbon fiber and carbon black. It can be seen from Comparative Example 4 compared to Example 2 and Comparative Example 5 compared to Example 3 that carbon fiber helps to improve mechanical strength and HDT, and reduces surface resistance. It can be seen from Examples 1-5 that when the content of carbon fiber is less than 10wt% (for example, between 2-9wt%) and the content of carbon black is less than 10wt% (for example, between 0-9wt%), the surface resistance value of the PLA composition All are less than 10 ¹² ohm/sq, the impact strength is greater than 1.3 kg-cm/cm, the HDT is greater than 125℃ (up to 133℃ or higher), and the appearance of the injection molded product is rated well, and it can be used as an excellent antistatic Material. In particular, the surface resistance values of Examples 2-4 are all less than 10 ¹⁰ ohm/sq, and have very excellent antistatic properties. Among them, the surface resistance value of Example 4 reaches 152.32 ohm/sq, which has better antistatic properties.

In addition, if the PLA composition is to be made into a tray for electronic parts, it needs to have good impact strength. For example, when the impact strength is greater than or equal to 1.5 kg-cm/cm, the PLA composition can be used as Trays for electronic parts. It can be seen from Examples 1, 2, 3 and 5 that when the content of carbon fiber is less than 10wt% (for example, between 2-9wt%) and the content of carbon black is less than 7wt% (for example, between 0-6wt%), its impact resistance The strength is greater than 1.5 kg-cm/cm and can be used to make trays for electronic parts.

In addition, if the PLA composition is to be made into a tray for electronic parts, it needs to have a higher HDT. For example, when its HDT is greater than or equal to 125°C, the PLA composition can be used as a pallet for electronic parts. pallet. It can be seen from Examples 1 to 5 that their HDTs are all greater than or equal to 133°C, indicating excellent HDT.

In general, the PLA compositions produced by Examples 1-5 by containing a specific content of carbon fiber or further adding a specific content of carbon black have good antistatic properties and can be used as antistatic materials, and among Examples 1, 2, 3, The PLA composition of 5 can also be made into pallets. These pallets have appropriate HDT and mechanical properties and can be used in the electronics industry, such as IC pallets.

As used herein and not otherwise defined, the terms "substantially," "substantially," "approximately" and "approximately" are used for description and allow for minor variations. When used in connection with an event or situation, the term can cover the exact occurrence of the event or situation as well as the close approximation of the event or situation. For example, when used in conjunction with a numerical value, the term may encompass a range of less than or equal to ±10% of that value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to Equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the first value is within a variation range of less than or equal to ±10% of the second value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ± 2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%, the first value can be "substantially" the same or equal to the second value.

As used herein, the singular terms "a/an" and "the" may include plural referents unless the context clearly dictates otherwise.

Quantities, ratios, and other numerical values are sometimes presented in this document in range format. It is understood that such range formats are used for convenience and brevity, and should be flexibly understood to include not only the values expressly designated as range limits, but also all individual values or subranges encompassed within the range, as if expressly Specify each value and subrange individually.

While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustrations do not limit the invention. It will be apparent to those skilled in the art that various changes may be made and equivalent elements may be substituted within the embodiments without departing from the true spirit and scope of the invention as defined by the appended claims. Instructions need not be drawn to scale. Differences may exist between the representations of the invention and the actual device due to variables in manufacturing processes and the like. There may be other embodiments of the invention not specifically illustrated. This specification and drawings are to be regarded as illustrative rather than restrictive. Modifications may be made to adapt a particular situation, materials, compositions of matter, methods or processes to the objectives, spirit and scope of the invention. All such modifications are intended to be within the scope of the patent claims appended hereto. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it will be understood that such operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of this disclosure. Therefore, unless specifically indicated herein, the order and grouping of operations are not limitations of the invention.

Claims (14)

A polylactic acid resin composition, including: (a) polylactic acid resin, its content is between 75-95wt%; (b) carbon fiber, its content is between 2-9wt%; (c) carbon black, its content is greater than 0, and Less than or equal to 9wt%; (d) nucleating agent, its content is between 0.001-5wt%; and (e) coupling agent, its content is between 0.001-5wt%, wherein the content is based on component (a), The total weight of (b), (c), (d) and (e) is based on 100wt%. The polylactic acid resin composition as claimed in claim 1, wherein the content of the carbon black is less than 7wt%. The polylactic acid resin composition of claim 1, wherein the total content of the carbon fiber and the carbon black is less than 15wt%. The polylactic acid resin composition of claim 1, wherein the particle size of the carbon fiber is in the range of 0.01 μm to 100 μm. The polylactic acid resin composition of claim 1, wherein the particle size of the carbon black is in the range of 0.01 μm to 100 μm. The polylactic acid resin composition of claim 1, wherein the nucleating agent includes metal carbonic acid At least one of a salt, an ester derivative of citric acid, a metal silicate, an amino acid, a poly(amino acid), a heterocyclic organic compound, and a metal oxide. The polylactic acid resin composition of claim 1, wherein the coupling agent includes a silane coupling agent or a titanate coupling agent or a combination thereof. The polylactic acid resin composition according to claim 1 has the following characteristics: the surface resistance measured according to ASTM D-257 is less than 10 ¹² ohm/sq. The polylactic acid resin composition as claimed in claim 1, wherein the carbon fiber content is 5% and the carbon black content is 7%. A tray for electronic parts, including: (a) polylactic acid resin, with a content between 75-95wt%; (b) carbon fiber, with a content between 2-9wt%; (c) carbon black, with a content greater than 0, And less than or equal to 6wt%; (d) nucleating agent, its content is between 0.001-5wt%; and (e) coupling agent, its content is between 0.001-5wt%, wherein the content is based on component (a) The total weight of (b), (c), (d) and (e) is 100wt%, and the total content of the carbon fiber and the carbon black is less than 15wt%. . The pallet of claim 10 has the following characteristics: an impact strength measured according to ASTM D-256 is greater than 1.5 kg-cm/cm. The pallet of claim 10 has the following characteristics: a surface resistance value measured according to ASTM D-257 of less than 10 ¹² ohm/sq. The pallet of claim 10 has the following characteristics: a surface resistance value measured according to ASTM D-257 ranging from 152 ohm/sq to 9.8×10 ¹¹ ohm/sq. The pallet according to claim 10 has the following characteristics: a heat distortion temperature measured according to ASTM D-648 is greater than 125°C.