A polylactic acid composite material and its application

Abstract

This invention provides a polylactic acid (PLA) composite material and its applications. The PLA composite material comprises, by weight, 85-95 parts PLA and 5.2-14.8 parts aliphatic-aromatic copolyester. The aliphatic-aromatic copolyester comprises the following components: Component A: an acid component comprising the following components: a1) 62-70 mol% terephthalic acid or its derivatives, or mixtures thereof, based on the total molar amount of a1) and a2); a2) 30-38 mol% adipic acid or its derivatives, or mixtures thereof, based on the total molar amount of a1) and a2); wherein the total molar percentage of a1) and a2) is 100 mol%; and Component B: 1,4-butanediol in at least an equimolar amount with Component A. In this invention, the PLA composite material exhibits high gloss, good aging resistance, high bending cycles after aging, and good toughness.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing materials technology, specifically relating to a polylactic acid composite material and its applications. Background Technology

[0002] 3D printing refers to the use of digital technology to construct three-dimensional products based on digital model files using various adhesive materials. Depending on the characteristics of different printing materials, their applications vary. Polylactic acid (PLA) is one of the most widely used 3D printing materials due to its environmental friendliness. Unlike its previous use solely for model making, many 3D printing materials are now being used in the mass production of various products, integrating into the manufacturing processes of multiple fields.

[0003] Although PLA material exhibits good flowability, resistance to cracking and warping during printing, and odorlessness during the printing process, its inherent brittleness and low impact strength limit its further application in 3D printing. To improve the material's impact performance, current technologies typically involve adding toughening agents or blending it with aliphatic-aromatic polyesters. For example, commercially available aliphatic-aromatic polyester PBAT (with a terephthalate molar content of 44-50 mol%) can improve the notched impact performance of PLA material by approximately 10% when added at 5-10 wt%. However, commercially available aliphatic-aromatic polyester PBAT is mostly yellow or reddish-brown. Adding this yellow or reddish-brown PBAT to PLA material weakens its gloss, resulting in a dark yellow 3D printed filament, which does not meet current aesthetic demands for 3D printing materials.

[0004] Therefore, developing a polylactic acid composite material that improves the gloss and aging resistance of the material while ensuring its toughness is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a polylactic acid (PLA) composite material and its applications. The PLA composite material provided by the present invention exhibits high gloss, good aging resistance, and good toughness.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a polylactic acid composite material, wherein, by weight, the polylactic acid composite material comprises 85-95 parts of polylactic acid (e.g., 85 parts, 85.5 parts, 86 parts, 86.5 parts, 87 parts, 87.5 parts, 88 parts, 88.5 parts, 89 parts, 89.5 parts, 90 parts, 90.5 parts, 91 parts, 91.5 parts, 92 parts, 92.5 parts, 93 parts, 93.5 parts, 94 parts, 94.5 parts, 95 parts, etc.) and 5.2-14.8 parts of aliphatic-aromatic copolyester (e.g., 5.2 parts, 5.5 parts, 5.8 parts, 6 parts, etc.). 6.2 parts, 6.5 parts, 6.8 parts, 7 parts, 7.2 parts, 7.5 parts, 7.8 parts, 8 parts, 8.2 parts, 8.5 parts, 8.8 parts, 9 parts, 9.2 parts, 9.5 parts, 9.8 parts, 10 parts, 10.2 parts, 10.5 parts, 10.8 parts, 11 parts, 11.2 parts, 11.5 parts, 11.8 parts, 12 parts, 12.2 parts, 12.5 parts, 12.8 parts, 13 parts, 13.2 parts, 13.5 parts, 13.8 parts, 14 parts, 14.2 parts, 14.5 parts, 14.8 parts, etc.); the aliphatic-aromatic copolyester comprises the following components:

[0008] Component A:

[0009] An acidic component containing the following components:

[0010] a1) Based on the total molar amount of a1) and a2), 62-70 mol% of terephthalic acid or its derivatives or mixtures thereof;

[0011] a2) Based on the total molar amount of a1) and a2), 30–38 mol% of adipic acid or its derivatives or mixtures thereof;

[0012] The total molar percentage of a1) and a2) is 100 mol%.

[0013] and,

[0014] Component B: 1,4-Butanediol in at least an equimolar amount as component A.

[0015] In this invention, by using an aliphatic-aromatic copolyester with a specific structure and polylactic acid, and with the contents of both within a specific range, the polylactic acid composite material can achieve both good toughness and high gloss and aging resistance, resulting in 3D printing materials containing it having a silky luster and excellent performance.

[0016] In this invention, the 62-70 mol% can be, for example, 62.2 mol%, 62.5 mol%, 62.8 mol%, 63 mol%, 63.2 mol%, 63.4 mol%, 63.6 mol%, 63.8 mol%, 64 mol%, 64.2 mol%, 64.4 mol%, 64.6 mol%, 64.8 mol%, 65 mol%, 65.2 mol%, 65.4 mol%, 65.6 mol%, 65.8 mol%, etc. l%, 66mol%, 66.2mol%, 66.4mol%, 66.6mol%, 66.8mol%, 67mol%, 67.2mol%, 67.4mol%, 67.6mol%, 67.8mol %, 68 mol%, 68.2 mol%, 68.4 mol%, 68.6 mol%, 68.8 mol%, 69 mol%, 69.2 mol%, 69.5 mol%, 69.8 mol%, 70 mol%, etc.

[0017] In this invention, the aliphatic-aromatic copolyester comprises the following components, referring to the repeating units or molecular chain structures composed of the following components in the molecular structure of the aliphatic-aromatic copolyester; for example, including components A and B means including repeating units derived from components A and B; including components C and D means that the molecular structure contains structures derived from components C and D, and the aforementioned molar content refers to the molar content of structural units derived from terephthalic acid or its derivatives in the molecular structure of the aliphatic-aromatic copolyester.

[0018] In this invention, the derivative of terephthalic acid can be a di-C1-C6 alkyl ester of terephthalic acid, exemplarily such as dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, or di-n-hexyl ester. The derivative of terephthalic acid can be used alone or in a mixture of two or more. Particularly preferred are derivatives of terephthalic acid or its esters, such as dimethyl terephthalate.

[0019] In this invention, the derivative of adipic acid can be a di-C1-C6 alkyl ester of adipic acid, exemplarily such as dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, or di-n-hexyl ester. The derivative of adipic acid can be used alone or in a mixture of two or more.

[0020] Preferably, the aliphatic-aromatic copolyester further comprises component C.

[0021] Preferably, based on 100 wt% of the aliphatic-aromatic copolyester, the mass percentage of component C is 0.01-1 wt%, for example, it can be 0.01 wt%, 0.02 wt%, 0.04 wt%, 0.05 wt%, 0.055 wt%, 0.06 wt%, 0.065 wt%, 0.07 wt%, 0.075 wt%, 0.08 wt%, 0.085 wt%, 0.09 wt%, 0.095 wt%, 0.1 wt%, 0.12 wt%, 0.14 wt%, 0.16 wt%, 0.18 wt%, 0.2 wt%, 0.22 wt%, 0.25 wt%, 0.28 wt%, 0.3 wt%, 0. 32wt%, 0.35wt%, 0.38wt%, 0.4wt%, 0.42wt%, 0.45wt%, 0.48wt%, 0.5wt%, 0.52wt%, 0.55wt%, 0.58wt%, 0.6wt%, 0.62wt%, 0.65wt%, 0.68wt%, 0.7wt%, 0.72wt%, 0.75wt%, 0.78wt%, 0.8wt%, 0.82wt%, 0.85wt%, 0.88wt%, 0.9wt%, 0.92wt%, 0.95wt%, 0.98wt%, 1wt%, etc.; preferably 0.05-0.9wt%, more preferably 0.1-0.5wt%.

[0022] Preferably, component C is a crosslinking agent with at least three functionalities, such as 3, 4, 5, 6, etc.

[0023] In this invention, component C is preferably a compound having 3 to 6 hydroxyl groups.

[0024] Preferably, component C includes at least one selected from tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyethertriol, glycerol, 1,3,5-benzotriic acid, 1,2,4-benzotriic acid, 1,2,4-benzotriic anhydride, 1,2,4,5-benzotetraic acid, or benzopyrenic acid dianhydride, more preferably trimethylolpropane, pentaerythritol, or glycerol, and particularly preferably glycerol.

[0025] Preferably, the aliphatic-aromatic copolyester further comprises component D.

[0026] Preferably, based on 100 wt% of the aliphatic-aromatic copolyester, the mass percentage of component D is 0.01–1 wt%, for example, it can be 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.055 wt%, 0.06 wt%, 0.065 wt%, 0.07 wt%, 0.075 wt%, 0.08 wt%, 0.085 wt%, 0.09 wt%, 0.095 wt%, 0.1 wt%, 0.12 wt%, 0.14 wt%, 0.16 wt%, 0.18 wt%, 0.2 wt%, 0.22 wt%, 0.25 wt%, 0.28 wt%, 0.3 wt%, or 0.32 wt%. The concentrations are 0.35wt%, 0.38wt%, 0.4wt%, 0.42wt%, 0.45wt%, 0.48wt%, 0.5wt%, 0.52wt%, 0.55wt%, 0.58wt%, 0.6wt%, 0.62wt%, 0.65wt%, 0.68wt%, 0.7wt%, 0.72wt%, 0.75wt%, 0.78wt%, 0.8wt%, 0.82wt%, 0.85wt%, 0.88wt%, 0.9wt%, 0.92wt%, 0.95wt%, 0.98wt%, 1wt%, etc., preferably 0.05-0.8wt%, more preferably 0.12-0.65wt%.

[0027] Preferably, component D is a chain extender with a functionality ≥2, such as 2, 3, 4, 5, etc.

[0028] Preferably, the chain extender comprises at least one of isocyanate compounds, isocyanurate compounds, peroxides, epoxides, oxazoline compounds, oxazine compounds, caprolactam, or carbodiimide, and more preferably isocyanate compounds.

[0029] In this invention, the isocyanate compounds may be aromatic diisocyanates and / or aliphatic diisocyanates; wherein, the aromatic diisocyanate may be toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, diphenylmethane 2,2′-diisocyanate, diphenylmethane 2,4′-diisocyanate, diphenylmethane 4,4′-diisocyanate, naphthalene 1,5-diisocyanate, or xylene diisocyanate. The aliphatic diisocyanate may be any straight-chain or branched alkylene diisocyanate or cycloalkylene diisocyanate containing 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example, hexamethylene diisocyanate, isophorone diisocyanate, or methylene di(4-isocyanate cyclohexane); a particularly preferred aliphatic diisocyanate is hexamethylene diisocyanate.

[0030] In this invention, the peroxides include, but are not limited to, benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)methylcyclododecane, n-butyl 4,4-di(butylperoxy)valerate, dicumyl peroxide, tert-butyl peroxybenzoate, dibutyl peroxide, α,α-di(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne, or tert-butylperoxycumene.

[0031] The epoxides described in this invention include, but are not limited to, hydroquinone, diglycidyl ether, resorcinol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl terephthalate, tetrahydrophthalic acid diglycidyl ether, hexahydrophthalic acid diglycidyl ether, dimethyl phthalic acid diglycidyl ether, phenylene diglycidyl ether, ethylene diglycidyl ether, trimethylene diglycidyl ether, tetramethylene diglycidyl ether, and hexamethylene diglycidyl ether. One or more of the following: sorbitol diglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, or polybutylene glycol diglycidyl ether. Preferably, it is a copolymer based on styrene, acrylate, and / or methacrylate containing epoxy groups, wherein the epoxy-containing unit is preferably (meth)acrylate glycidyl ether.

[0032] In this invention, the oxazoline compounds and oxazine compounds each independently include a bridging portion consisting of a single bond or -(CH2). z - or arylene dioxazoline and dioxazine, wherein z = 2, 3 or 4, such as methylene, ethyl-1,2-diyl, propion-1,3-diyl, propion-1,2-diyl, etc.; the arylene group includes phenylene.

[0033] In this invention, the dioxazoline is preferably at least one of 2,2′-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, 1,4-bis(2-oxazolinyl)butane, 1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-oxazolinyl)benzene.

[0034] The dioxazine is preferably at least one of 2,2′-bis(2-dioxazine), bis(2-dioxazinyl)methane, 1,2-bis(2-dioxazinyl)ethane, 1,3-bis(2-dioxazinyl)propane, 1,4-bis(2-dioxazinyl)butane, 1,4-bis(2-dioxazinyl)benzene, 1,2-bis(2-dioxazinyl)benzene, or 1,3-bis(2-dioxazinyl)benzene.

[0035] In this invention, the carbodiimide can be at least one of the following: N,N′-di-2,6-diisopropylphenylcarbodiimide, N,N′-di-o-tolylcarbodiimide, N,N′-diphenylcarbodiimide, N,N′-dioctyldecylcarbodiimide, N,N′-di-2,6-dimethylphenylcarbodiimide, N-tolyl-N′-cyclohexylcarbodiimide, N,N′-di-2,6-di-tert-butylphenylcarbodiimide, N,N′-di-2,4,6-triisobutylphenylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, di-β-naphthylcarbodiimide, or di-tert-butylcarbodiimide.

[0036] Preferably, the aliphatic-aromatic copolyester has an acid value of <1.68 mgKOH / g, more preferably <1.40 mgKOH / g, and even more preferably <0.90 mgKOH / g.

[0037] In this invention, the acid value of the aliphatic-aromatic copolyester is tested according to the DIN EN 12634-1998 test method. The lower the acid value, the more beneficial it is to weaken the thermal degradation problem that may occur during the processing of polylactic acid composite materials, thereby ensuring that the material has suitable gloss and mechanical properties.

[0038] Preferably, the whiteness index of the aliphatic-aromatic copolyester is ≥28, and more preferably ≥34.

[0039] In this invention, the whiteness index of the aliphatic-aromatic copolyester is tested according to the ASTM E313-73 test method.

[0040] Preferably, the viscosity of the aliphatic-aromatic copolyester is 138-272 mL / g, for example, it can be 140 mL / g, 145 mL / g, 150 mL / g, 155 mL / g, 160 mL / g, 165 mL / g, 170 mL / g, 175 mL / g, 180 mL / g, 185 mL / g, 190 mL / g, 195 mL / g, 200 mL / g, 205 mL / g, 210 mL / g, 215 mL / g, 220 mL / g, 225 mL / g, 230 mL / g, 235 mL / g, 240 mL / g, 245 mL / g, 250 mL / g, 255 mL / g, 260 mL / g, 265 mL / g, 270 mL / g, etc.

[0041] In this invention, according to the ISO 1133-2-2011 (190°C, 2.16 kg) method, the melt flow rate of the aliphatic-aromatic copolyester is 2 to 12 g / 10 min, for example, it can be 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, 6 g / 10 min, 6.5 g / 10 min, 7 g / 10 min, 7.5 g / 10 min, 8 g / 10 min, 8.5 g / 10 min, 9 g / 10 min, 9.5 g / 10 min, 10 g / 10 min, 10.5 g / 10 min, 11 g / 10 min, 11.5 g / 10 min, 12 g / 10 min, etc.; more preferably, it is 3 to 10 g / 10 min.

[0042] Preferably, the aliphatic-aromatic copolyester can be commercially available or prepared using conventional processes in the prior art. Preferably, it is prepared using the following method, which includes:

[0043] (1) React component A with component B to obtain an esterified product;

[0044] (2) The esterified product obtained in step (1) is subjected to a pre-condensation reaction to obtain a pre-condensation product;

[0045] (3) The prepolymerization product obtained in step (2) is subjected to a polycondensation reaction to obtain the aliphatic-aromatic copolyester; the molar percentage of terephthalic acid or its derivatives or mixtures thereof in component A is 62-70 mol%.

[0046] Preferably, the raw materials for the reaction in step (1) further include component C.

[0047] Preferably, the viscosity of the esterified product in step (1) is 12 to 33 mL / g, for example, it can be 12 mL / g, 13 mL / g, 14 mL / g, 16 mL / g, 18 mL / g, 20 mL / g, 22 mL / g, 24 mL / g, 26 mL / g, 28 mL / g, 30 mL / g, 32 mL / g, 33 mL / g, etc., and more preferably 18 to 22 mL / g.

[0048] Preferably, the viscosity of the prepolymerized product in step (2) is 33-76 mL / g, for example, it can be 33 mL / g, 34 mL / g, 35 mL / g, 36 mL / g, 38 mL / g, 40 mL / g, 42 mL / g, 45 mL / g, 48 mL / g, 50 mL / g, 52 mL / g, 55 mL / g, 58 mL / g, 60 mL / g, 62 mL / g, 65 mL / g, 68 mL / g, 70 mL / g, 72 mL / g, 74 mL / g, 76 mL / g, etc., and more preferably 35-50 mL / g.

[0049] Preferably, after the polycondensation reaction, the process further includes mixing the polycondensation product with a chain extender to carry out a chain extension reaction.

[0050] Preferably, the viscosity of the condensation product is 138-240 mL / g, for example, it can be 138 mL / g, 140 mL / g, 145 mL / g, 150 mL / g, 155 mL / g, 160 mL / g, 165 mL / g, 170 mL / g, 175 mL / g, 180 mL / g, 185 mL / g, 190 mL / g, 195 mL / g, 200 mL / g, 205 mL / g, 210 mL / g, 215 mL / g, 220 mL / g, 225 mL / g, 230 mL / g, 235 mL / g, 240 mL / g, etc.; more preferably, it is 140.5-144.5 mL / g.

[0051] Preferably, the viscosity of the product obtained by the chain extension reaction is 150-270 mL / g, for example, it can be 150 mL / g, 152 mL / g, 154 mL / g, 156 mL / g, 158 mL / g, 160 mL / g, 165 mL / g, 170 mL / g, 175 mL / g, 180 mL / g, 185 mL / g, 190 mL / g, 195 mL / g, 200 mL / g, 205 mL / g, 210 mL / g, 215 mL / g, 220 mL / g, 225 mL / g, 230 mL / g, 235 mL / g, 240 mL / g, 245 mL / g, 250 mL / g, 255 mL / g, 260 mL / g, 265 mL / g, 270 mL / g, etc., and more preferably 180-190 mL / g.

[0052] In this invention, no chain extension reaction is performed, and the resulting polycondensation product is the aliphatic-aromatic copolyester; in order to better control the acid value, a chain extension reaction is preferably performed, and the chain extension reaction product is the aliphatic-aromatic copolyester.

[0053] Preferably, the reaction in step (1) is carried out at a temperature of 180–265°C, a pressure of 40–120 kPa, and a time of 2–8 h; more preferably, the temperature is 220–250°C, the pressure is 60–90 kPa, and the time is 3–6 h.

[0054] In this invention, the molar ratio of component A to component B in step (1) is 1:(1.2 to 2.4), wherein the specific values ​​of (1.2 to 2.4) can be, for example, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, etc.; and more preferably 1:(1.4 to 1.8).

[0055] In this invention, the reaction described in step (1) can be carried out in a mixing device, such as a vertical reactor with a stirrer.

[0056] Preferably, the temperature of the pre-condensation reaction in step (2) is 230-270°C; the pressure is 450-3000Pa; and the time is 2-7h; more preferably, the temperature is 240-260°C, the pressure is 800-2100Pa, and the time is 3-5h.

[0057] Preferably, the temperature of the polycondensation reaction in step (3) is 230-270°C; the pressure is 50-600 Pa; and the time is 2-6 h; more preferably, the temperature is 240-260°C, the pressure is 100-300 Pa, and the time is 3-5 h.

[0058] In this invention, the polycondensation reaction is carried out in a rotating disc reactor or a cage reactor.

[0059] Preferably, the chain extension reaction is carried out at a temperature of 180–235°C for 3–15 minutes.

[0060] In this invention, the chain extension reaction is carried out in a twin-screw extruder or a static mixer.

[0061] In this invention, the viscosity numbers mentioned are all determined according to the method specified in GB / T 17931-1999, in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1, in a constant temperature water bath at 25±0.05℃.

[0062] In this invention, steps (1)-(3) and the chain extension reaction are carried out independently in the presence of a catalyst, and the catalysts used in steps (1)-(3) and the chain extension reaction can be the same or different. The catalyst can be an external catalyst or a catalyst present in the system. For example, in the reaction described in step (1), 50-80 wt% of the total mass of the catalyst is added; in the reaction described in step (2), the remaining catalyst is added; and the catalyst required for step (3) and the chain extension reaction is a catalyst present in the system. Controlling the amount of catalyst added can make the subsequent processing more stable. The total mass of the catalyst is 0.001-1 wt% of the mass of the aliphatic-aromatic copolyester, for example, it can be 0.001 wt%, 0.002 wt%, 0.005 wt%, 0.008 wt%, 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, etc.; preferably 0.03-0.2 wt%.

[0063] In this invention, the catalyst may be a tin compound, antimony compound, cobalt compound, lead compound, zinc compound, aluminum compound, or titanium compound, more preferably a zinc compound, aluminum compound, or titanium compound, and most preferably a titanium compound; the titanium compound may be tetrabutyl titanate or tetraisopropyl titanate, which has less residual amount and lower toxicity in the product or downstream product compared to other compounds.

[0064] In this invention, the system of the polycondensation reaction in step (3) may, as needed, include a catalyst passivator, which is preferably a phosphorus compound; the phosphorus compound includes, but is not limited to, organic phosphites, phosphorous acid, or phosphoric acid; particularly preferably, if a highly active titanium catalyst is used, a passivator may be added. The amount of passivator added may be 0.001 to 0.1 wt%, preferably 0.01 to 0.05 wt%, and the Ti / P ratio (molar ratio) based on the mass of the polycondensation product obtained in step (3) is preferably set to 1.1 to 1.5:1, particularly preferably 1.1 to 1.3:1.

[0065] In this invention, a color stabilizer may be included in the polycondensation reaction system described in step (3), if necessary. Suitable color stabilizers are, in particular, phosphorus compounds such as phosphoric acid, phosphorous acid, triphenyl phosphite, sodium hypophosphite, and sodium phosphite. These phosphorus compounds may also be used in mixtures. The use of color stabilizers generally results in a decrease in the condensation rate. Triphenyl phosphite is a particularly suitable color stabilizer because it has no adverse effect on the condensation rate.

[0066] In this invention, the amount of color stabilizer added can be 0.001 to 1.5 wt%, preferably 0.01 to 1.0 wt%. Based on the mass of the polycondensation product obtained in step (3), the Ti / P ratio (mol / mol) is preferably set to 1.0:0.3 to 1.0, and particularly preferably 1.0:0.5 to 1.0.

[0067] In this invention, an activator may be included in the polycondensation reaction system described in step (3) as needed. Suitable activators are, in particular, phosphorus compounds. Examples include disodium hydrogen phosphate, calcium hypophosphite, calcium phosphite, calcium phosphate, sodium hypophosphite, sodium phosphite, triphenyl phosphite, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, etc. These phosphorus compounds may also be used in mixtures. Particularly suitable activators are disodium hydrogen phosphate and sodium phosphite.

[0068] In this invention, the amount of activator added can be 0.001 to 1.5 wt%, preferably 0.01 to 1.0 wt%. Based on the mass of the polycondensation product obtained in step (3), the Ti / P ratio (mol / mol) is preferably set to 1.0 to 1.5:1, and particularly preferably 1.1 to 1.3:1. Among these, the combined use of color stabilizer and activator is of particular interest, an example being triphenyl phosphate / disodium hydrogen phosphate.

[0069] Preferably, the polylactic acid composite material further includes 0 to 1 parts by weight of a copolymer containing epoxy groups, more preferably 0.01 to 0.8 parts, and more preferably 0.05 to 0.5 parts.

[0070] Preferably, the epoxy-containing copolymer includes at least one of a copolymer of styrene and acrylate, a copolymer of styrene and methacrylate, or a copolymer of styrene, acrylate, and methacrylate.

[0071] In this invention, the epoxy-containing copolymers preferably contain glycidyl (meth)acrylate units. Advantageous copolymers are those with a glycidyl methacrylate content greater than 20% by weight, particularly preferably greater than 30% by weight, and especially preferably greater than 50% by weight. In the polymer, the epoxy equivalent (EEW) is preferably 150–3000 g / equivalent, and particularly preferably 200–500 g / equivalent. The average molecular weight (weight-average Mw) of the polymer is preferably 2000–25000, particularly 3000–8000. The average molecular weight (number-average Mn) of the polymer is preferably 400–6000, particularly 1000–4000. The polydispersity (Q) is typically 1.5–5. The above-mentioned epoxy-containing copolymers can be, for example,... ADR was purchased from BASF Resins BV. Among them, ADR4368 is particularly suitable. Epoxy-containing copolymers are especially suitable for PLA-containing materials.

[0072] Preferably, the polylactic acid has a melting point of 140-180°C, such as 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, etc., with 145-170°C being the most preferred.

[0073] In this invention, the melt flow rate of the polylactic acid is 1.0 to 12 g / 10 min, for example, it can be 1 g / 10 min, 2 g / 10 min, 4 g / 10 min, 6 g / 10 min, 8 g / 10 min, 10 g / 10 min, 12 g / 10 min, etc.; preferably 2 to 6 g / 10 min; test standard: ISO 1133-2-2011 (190℃, 2.16 kg).

[0074] Preferably, the mass content of polylactic acid D-type is 0.3% to 4.8%, for example, it can be 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, etc., preferably 0.5% to 4%.

[0075] In this invention, the polylactic acid has a glass transition temperature (Tg) higher than 55°C, a water content less than 1000 ppm, a residual monomer content (Lactid) less than 0.3%, and a molecular weight greater than 80,000 Daltons. The polylactic acid includes, but is not limited to, Nature... 2500HP, 3100HP, 4044D, 4043D, 3001D, L175, L130, LX175, LX575, LX530, and at least one of Fengyuan FY801, FY601, FY804, FY802 or FY602; more preferably at least one of 4044D, 4043D, LX175 or FY804.

[0076] The melting point and glass transition temperature of polylactic acid (PLA) described in this invention can be determined by differential scanning calorimetry (DSC). A 5-10 mg sample is placed in a crucible and tested using a NETZSCH DSC instrument. The test procedure is as follows: initial temperature: 20°C; heating to 200°C at a rate of 10 K / min; holding at 200°C for 5 minutes; cooling to 20°C at a rate of 10 K / min; holding at 20°C for 3 minutes; heating to 200°C at a rate of 10 K / min; holding at 200°C for 2 minutes; cooling to 50°C at a rate of 20 K / min. The entire test is conducted under nitrogen protection.

[0077] In this invention, to further improve the toughness and crystallinity of the polylactic acid composite material, the polylactic acid composite material further includes an aliphatic polyester. By weight, the polylactic acid composite material further includes 3 to 15 parts of aliphatic polyester, for example, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc.

[0078] Preferably, the aliphatic polyester comprises structural units derived from at least one aliphatic dicarboxylic acid compound and structural units derived from at least one aliphatic diol compound.

[0079] In this invention, the aliphatic dicarboxylic acid compound includes at least one of aliphatic dicarboxylic acid, aliphatic dicarboxylic acid ester, or aliphatic dicarboxylic acid anhydride; the main chain structure of the aliphatic dicarboxylic acid compound contains 2 to 22 carbon atoms, for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, etc.

[0080] Preferably, the aliphatic dicarboxylic acid compound includes succinic acid, adipic acid, azelaic acid, sebacic acid, tridecanoic acid and / or mixtures thereof, more preferably succinic acid and / or adipic acid.

[0081] In this invention, the aliphatic diol compounds include aliphatic diols having 2 to 13 carbon atoms in their main chain, preferably at least one of 1,2-ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, or 1,13-tridecanediol; more preferably 1,4-butanediol and / or 1,3-propanediol.

[0082] Preferably, the aliphatic polyester comprises the following components:

[0083] ii-1) An acidic component containing the following components:

[0084] ii-1.1) Based on the total molar percentage content of ii-1.1) and ii-1.2), 65–100 mol% (e.g., 65 mol%, 66 mol%, 67 mol%, 68 mol%, 69 mol%, 70 mol%, 71 mol%, 72 mol%, 73 mol%, 73.5 mol%, 74 mol%, 74.5 mol%, 75 mol%, 75.5 mol%, 76 mol%, 76.5 mol%, 77 mol%, 77.5 mol%, 78 mol%). Succinic acid or its derivatives, or mixtures thereof, in concentrations of 78.5 mol%, 79 mol%, 79.5 mol%, 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, 85 mol%, 86 mol%, 87 mol%, 88 mol%, 89 mol%, 90 mol%, 91 mol%, 92 mol%, 93 mol%, 94 mol%, 95 mol%, 96 mol%, 97 mol%, 98 mol%, 99 mol%, 100 mol%, etc.

[0085] ii-1.2) Based on the total molar percentage content of ii-1.1) and ii-1.2), 0 to 35 mol% (e.g., 0 mol%, 1 mol%, 2 mol%, 4 mol%, 6 mol%, 8 mol%, 10 mol%, 12 mol%, 14 mol%, 16 mol%, 18 mol%, 20 mol%, 22 mol%, 24 mol%, 26 mol%, 28 mol%, 30 mol%, 32 mol%, 34 mol%, 35 mol%, etc.) of adipic acid or its derivatives, or mixtures thereof;

[0086] and,

[0087] ii-2) at least equal molar amounts of C3-C4 aliphatic diols as component ii-1).

[0088] In this invention, the total molar percentage of components ii-1.1) and ii-1.2) is 100 mol%. The succinic acid or its derivatives, or mixtures thereof, comprises any one or a combination of at least two of succinic acid, succinic ester, and succinic anhydride. The adipic acid or its derivatives, or mixtures thereof, comprises any one or a combination of at least two of adipic acid, adipic ester, and adipic anhydride. The C3-C4 aliphatic diol comprises 1,4-butanediol and / or 1,3-propanediol.

[0089] Preferably, the aliphatic polyester comprises the following components:

[0090] ii-1) An acidic component containing the following components:

[0091] ii-1.1) Based on the total molar percentage of ii-1.1) and ii-1.2), 73 to 80 mol% of succinic acid or its derivatives or mixtures thereof;

[0092] ii-1.2) Based on the total molar percentage of ii-1.1) and ii-1.2), 20–27 mol% of adipic acid or its derivatives or mixtures thereof;

[0093] and,

[0094] ii-2) at least equal molar amounts of C3-C4 aliphatic diols as component ii-1).

[0095] In this invention, the aliphatic polyester is based on ISO The melt mass flow rate (MFR) of 1133-2-2011 (190℃, 2.16kg) is typically 1.0 to 40.0 g / 10min, for example, it can be 1 g / 10min, 2 g / 10min, 4 g / 10min, 6 g / 10min, 8 g / 10min, 10 g / 10min, 12 g / 10min, 14 g / 10min, 16 g / 10min, 18 g / 10min, 20 g / 10min, 22 g / 10min, 24 g / 10min, 26 g / 10min, 28 g / 10min, 30 g / 10min, 32 g / 10min, 34 g / 10min, 36 g / 10min, 38 g / 10min, 40 g / 10min, etc.; preferably 2.5 to 32 g / 10min, and particularly preferably 3.5 to 22 g / 10min.

[0096] In this invention, in order to further reduce the cost of polylactic acid composite materials or improve the crystallization performance of the materials, the polylactic acid composite material further includes 0.5 to 10 parts of inorganic filler by weight, for example, 0.5 parts, 0.8 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0097] Preferably, the inorganic filler includes at least one of talc, calcium carbonate, chalk, calcium oxide, kaolin, silicon dioxide, titanium dioxide, silicate, mica, or montmorillonite.

[0098] In this invention, the preparation method of the polylactic acid composite material includes, but is not limited to: mixing the components evenly and then extruding them in an extruder via reactive extrusion to obtain the polylactic acid composite material.

[0099] In this invention, the extruder can be a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, with an extrusion temperature of 160–230°C and a screw speed of 300–500 rpm.

[0100] In this invention, the gloss of the polylactic acid composite material is ≥72, preferably ≥81, and particularly preferably ≥90.

[0101] In this invention, the notched impact strength of the polylactic acid composite material is ≥6.0 KJ / m. 2 Preferred concentration: ≥8.9 KJ / m 2 .

[0102] In a second aspect, the present invention provides a 3D printing material, the 3D printing material comprising the polylactic acid composite material according to the first aspect.

[0103] Preferably, the 3D printing material includes 3D printing filament.

[0104] The polylactic acid composite material mentioned in this invention, and the articles prepared therefrom, are all biodegradable.

[0105] For the purposes of this invention, a substance or mixture of substances is considered "biodegradable" if it exhibits a biodegradability of at least 90%, as defined in DIN EN 13432.

[0106] According to DIN EN 13432, during composting, CO2-free air is introduced into the maturing compost, and the compost is subjected to a specific temperature process. Here, biodegradability is defined as the percentage degree of biodegradation expressed as the ratio of the net amount of CO2 released by the sample (minus the amount of CO2 released by compost without the sample) to the maximum amount of CO2 that the sample can release (calculated from the carbon content in the sample). After only a few days of composting, biodegradable polyesters and biodegradable polyester mixtures typically show obvious signs of degradation, such as fungal growth, lysis, and perforation.

[0107] Other methods for determining biodegradability are described, for example, in ASTM D5338 and ASTM D6400.

[0108] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0109] The system refers to an equipment system, device system, or production device.

[0110] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0111] The polylactic acid composite material provided by the present invention is made by compounding aliphatic-aromatic copolyester with polylactic acid in a specific structure, and the contents of the two are within a specific range. This makes the polylactic acid composite material have high gloss, good aging resistance, high bending resistance after aging, and good toughness. Detailed Implementation

[0112] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0113] The materials used in this invention are as follows:

[0114] 1,4-Butanediol was purchased from Xinjiang Meike Chemical Co., Ltd.

[0115] Terephthalic acid was purchased from Zhuhai INEOS Chemical Co., Ltd.

[0116] Adipic acid was purchased from Chongqing Huafeng Chemical Group Co., Ltd.

[0117] Glycerin was purchased from Aladdin;

[0118] Tetrabutyl titanate was purchased from Jianyi Chemical Import & Export Co., Ltd.

[0119] Hexamethylene diisocyanate was purchased from Aladdin;

[0120] Polylactic acid, grade FY804, was purchased from Anhui Fengyuan Futailai Polylactic Acid Co., Ltd.

[0121] copolymers based on styrene, acrylates and / or methacrylates and containing epoxy groups: ADR 4368, purchased from BASF Resins BV.

[0122] In this invention, the method for testing the molar content of aromatic dicarboxylic acids in the aliphatic-aromatic copolyester is as follows:

[0123] 20 mg of aliphatic-aromatic copolyester sample was dissolved in 0.6 mL of deuterated chloroform, and then 1H NMR was measured at room temperature using a Bruker AV500 nuclear magnetic resonance spectrometer, with the chloroform solvent peak located around 7.26 ppm.

[0124] References: Chen, X.; Chen, W.; Zhu, G.; Huang, F.; Zhang, J., Synthesis, 1H-NMR characterization, and biodegradation behavior of aliphatic–aromatic random copolyester. J. Appl. Polym. Sci. 2007, 104(4): 2643-2649. It can be seen that for aromatic dicarboxylic acids, such as terephthalic acid, the four hydrogen atoms on the benzene ring in the repeating unit appear around 8.10 ppm; for aliphatic dicarboxylic acids, such as adipic acid, the four hydrogen atoms in the two CH2 units adjacent to the carbonyl group in the repeating unit appear around 2.33 ppm. Thus, the molar content of the dicarboxylic acid component can be determined by the integral area (I0.10) of the peaks at 8.10 ppm and 2.33 ppm. T and I A )express:

[0125] The molar content of aromatic dicarboxylic acids in aliphatic-aromatic copolyesters = I T / (I T +I A )×100%;

[0126] The molar content of aliphatic dicarboxylic acids in aliphatic-aromatic copolyesters = I A / (I T +I A )×100%.

[0127] In this invention, the viscosity of the products was determined in accordance with GB / T 17931-1999 in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 in a constant temperature water bath at 25±0.05℃.

[0128] In this invention, the acid value of the aliphatic-aromatic copolyester is tested using the following method:

[0129] According to DIN EN 12634, pre-titrate the sample to determine the appropriate sample mass, ensuring that the volume of titrant consumed is 2-3 mL. Add the sample to the solvent mixture and heat to 70-85°C to completely dissolve all the sample into a clear solution. Maintain the solution temperature at 65-75°C during titration to prevent sample precipitation. If appropriate, use tetrabutylammonium hydroxide as the titrant, avoiding the use of highly toxic tetramethylammonium hydroxide. Simultaneously, to prevent the solvent mixture from absorbing CO2 from the air and affecting the volume of titrant consumed by the blank solvent, the blank solvent should be pretreated using the same procedure as the sample test, such as heating it to the same time and temperature, before titrating the blank solvent.

[0130] In this invention, the whiteness index of the aliphatic-aromatic copolyester is tested using the following method:

[0131] The whiteness index of aliphatic-aromatic polyester granules with a particle size ranging from 1.2 to 5.4 g / 100 granules was determined using a Minolta CM-5 spectrophotometer according to ASTM E313-73. Trials were performed in parallel, and the average value was determined. The granular material to be analyzed was filled into glass cuvettes (from Minolta) with a filling height of at least 3 cm. The granular material was compacted using pressure from the measuring head of the Minolta instrument.

[0132] Preparation Example 1

[0133] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0134] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 600 kg of 1,4-butanediol, 2.2 kg of glycerol and 0.390 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 235 °C and 80 kPa pressure for 3.5 h to obtain an esterification product with a viscosity of 20 mL / g.

[0135] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.305 kg of tetrabutyl titanate was added to the reactor, heated to 240 °C, and reacted at a pressure of 1800 Pa for 4.5 h. Most of the excess 1,4-butanediol was removed by distillation, and a prepolymer with a viscosity of 35 mL / g was obtained.

[0136] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 245°C and a pressure of 130Pa for 3 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 141 mL / g.

[0137] (4) The final polymer obtained in step (3) is introduced into a static mixer, 2.1 kg of hexamethylene diisocyanate is added, and after blending at 200 °C for 7 min, it is granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 182 mL / g.

[0138] Preparation Example 2

[0139] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0140] (1) 510 kg of terephthalic acid, 269 kg of adipic acid, 630 kg of 1,4-butanediol, 3.2 kg of glycerol and 0.360 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 230 °C and 90 kPa pressure for 3.5 h to obtain an esterification product with a viscosity of 18.5 mL / g.

[0141] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.340 kg of tetrabutyl titanate was added to the reactor and heated to 245 °C. The reaction was carried out at a pressure of 1460 Pa for 4.5 h. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer with a viscosity of 42 mL / g.

[0142] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 248°C and a pressure of 126Pa for 2.5 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 142 mL / g.

[0143] (4) The final polymer obtained in step (3) was introduced into a static mixer, 2.4 kg of hexamethylene diisocyanate was added, and after blending at 210 °C for 6 min, it was granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 185 mL / g.

[0144] Preparation Example 3

[0145] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0146] (1) 510 kg of terephthalic acid, 236 kg of adipic acid, 640 kg of 1,4-butanediol, 4.5 kg of pentaerythritol and 0.380 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 240 °C and 80 kPa pressure for 4 h to obtain an esterification product with a viscosity of 21.5 mL / g.

[0147] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.330 kg of tetrabutyl titanate was added to the reactor and heated to 245 °C. The reaction was carried out at a pressure of 1100 Pa for 4.5 h. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer with a viscosity of 48 mL / g.

[0148] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 246°C and a pressure of 110Pa for 2 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 144 mL / g.

[0149] (4) The final polymer obtained in step (3) was introduced into a static mixer, 3.0 kg of hexamethylene diisocyanate was added, and after blending at 195 °C for 7 min, it was granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 187 mL / g.

[0150] Preparation Example 4

[0151] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0152] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 600 kg of 1,4-butanediol, 1.5 kg of glycerol and 0.390 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 220 °C and 100 kPa pressure for 3 h to obtain an esterification product with a viscosity of 15 mL / g.

[0153] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.315 kg of tetrabutyl titanate was added to the reactor, heated to 248 °C, and reacted at a pressure of 2300 Pa for 5 h. Most of the excess 1,4-butanediol was removed by distillation, and a prepolymer with a viscosity of 34 mL / g was obtained.

[0154] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 248°C and a pressure of 160Pa for 3.5 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 140 mL / g.

[0155] (4) The final polymer obtained in step (3) is introduced into a static mixer, 1.2 kg of hexamethylene diisocyanate is added, and after blending reaction at 195 °C for 6 min, it is granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 165 mL / g.

[0156] Preparation Example 5

[0157] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0158] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 650 kg of 1,4-butanediol, 4.0 kg of glycerol and 0.430 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 250 °C and 110 kPa pressure for 5 h to obtain an esterification product with a viscosity of 25 mL / g.

[0159] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.380 kg of tetrabutyl titanate was added to the reactor, heated to 250 °C, and reacted at a pressure of 500 Pa for 6 h. Most of the excess 1,4-butanediol was removed by distillation, and a prepolymer with a viscosity of 65 mL / g was obtained.

[0160] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 252°C and a pressure of 230Pa for 3 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 147 mL / g.

[0161] (4) The final polymer obtained in step (3) was introduced into a static mixer, 2.8 kg of hexamethylene diisocyanate was added, and after blending at 220 °C for 12 min, it was granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 192 mL / g.

[0162] Preparation Example 6

[0163] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0164] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 680 kg of 1,4-butanediol, 4.8 kg of glycerol and 0.440 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 260 °C and 90 kPa pressure for 5 h to obtain an esterification product with a viscosity of 29 mL / g.

[0165] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.355 kg of tetrabutyl titanate was added to the reactor, heated to 260 °C, and reacted at a pressure of 580 Pa for 6 h. Most of the excess 1,4-butanediol was removed by distillation, and a prepolymer with a viscosity of 68 mL / g was obtained.

[0166] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 262°C and a pressure of 170Pa for 5.5 hours. The excess 1,4-butanediol and other by-products were removed by distillation to obtain a final polymer with a viscosity of 220 mL / g.

[0167] (4) The final polymer obtained in step (3) is introduced into a static mixer, 1.2 kg of hexamethylene diisocyanate is added, and after blending reaction at 210 °C for 7 min, it is granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 260 mL / g.

[0168] Preparation Example 7

[0169] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0170] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 660 kg of 1,4-butanediol, 4.5 kg of glycerol and 0.430 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 240 °C and 70 KPa pressure for 4 h to obtain an esterification product with a viscosity of 28 mL / g.

[0171] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.385 kg of tetrabutyl titanate was added to the reactor, heated to 245 °C, and reacted at a pressure of 1000 Pa for 5 h. Most of the excess 1,4-butanediol was removed by distillation, and a prepolymer with a viscosity of 58 mL / g was obtained.

[0172] (3) The prepolymer obtained in step (2) is transferred to a final polymerization reactor and polycondensed at a temperature of 248°C and a pressure of 110Pa for 5 hours. The excess 1,4-butanediol and other by-products are removed by distillation. Then, the prepolymer is granulated by an underwater granulator and dried to obtain the final polymer product, which is an aliphatic-aromatic copolyester with a viscosity of 180mL / g.

[0173] Preparation Example 8

[0174] This preparation example provides an aliphatic-aromatic copolyester, the preparation method of which includes:

[0175] (1) 510 kg of terephthalic acid, 208 kg of adipic acid, 700 kg of 1,4-butanediol, 7.6 kg of glycerol and 0.455 kg of tetrabutyl titanate were physically mixed at room temperature in an esterification reactor. The resulting mixture was then subjected to an esterification reaction at 245 °C and 100 kPa pressure for 7 h to obtain an esterification product with a viscosity of 32 mL / g.

[0176] (2) The esterification product obtained in step (1) was introduced into a vertical stirred fully mixed reactor. 0.415 kg of tetrabutyl titanate was added to the reactor and heated to 246 °C. The reaction was carried out at a pressure of 1200 Pa for 6.5 h. Most of the excess 1,4-butanediol was removed by distillation to obtain a prepolymer with a viscosity of 75 mL / g.

[0177] (3) The prepolymer obtained in step (2) was transferred to a final polymerization reactor and polycondensed at a temperature of 246°C and a pressure of 180Pa for 3 hours. The excess 1,4-butanediol and other byproducts were removed by distillation to obtain a prepolymer with a viscosity of 137 mL / g.

[0178] (4) The final polymer obtained in step (3) is introduced into a static mixer, 1.0 kg of hexamethylene diisocyanate is added, and after blending at 210 °C for 6 min, it is granulated and dried to obtain an aliphatic-aromatic copolyester with a viscosity of 155 mL / g.

[0179] Comparative Preparation Example 1

[0180] This comparative preparation example provides an aliphatic-aromatic copolyester, which differs from Preparation Example 1 only in that, in the preparation method of the aliphatic-aromatic copolyester, the total molar amount of terephthalic acid and adipic acid in step (1) remains unchanged, and the terephthalic acid content is adjusted so that the molar percentage of terephthalic acid in the aliphatic-aromatic copolyester is 58 mol% (based on a total molar amount of terephthalic acid and adipic acid of 100 mol%). The other steps and parameters are the same as in Preparation Example 1.

[0181] Comparative Preparation Example 2

[0182] This comparative preparation example provides an aliphatic-aromatic copolyester, which differs from Preparation Example 1 only in that, in the preparation method of the aliphatic-aromatic copolyester, the total molar amount of terephthalic acid and adipic acid in step (1) remains unchanged, and the terephthalic acid content is adjusted so that the molar percentage of terephthalic acid in the aliphatic-aromatic copolyester is 75 mol% (based on a total molar amount of terephthalic acid and adipic acid of 100 mol%). Other steps and parameters are the same as in Preparation Example 1.

[0183] Comparative preparation example 3

[0184] An aliphatic-aromatic copolyester, PBAT resin, grade TH801T, was purchased from Xinjiang Lanshan Tunhe Polyester Co., Ltd., with a terephthalic acid ester content of 48.3 mol%, an acid value of 1.81 mg KOH / g, and a whiteness index of 24.31.

[0185] The relevant parameters of the aliphatic-aromatic copolyesters provided in Preparation Examples 1-8 and Comparative Preparation Examples 1-2 of this invention are shown in Tables 1 and 2.

[0186] Table 1

[0187]

[0188] Table 2

[0189]

[0190] Examples 1-11, Comparative Examples 1-5

[0191] Examples 1-11 and Comparative Examples 1-5 each provide a polylactic acid (PLA) composite material. The formulations of the PLA composite materials are shown in Table 3, by weight. The preparation method of the PLA composite material includes: mixing the components and feeding them into a twin-screw extruder (L / D = 48; diameter 40 mm) for melt mixing, extrusion granulation, extrusion temperature 180-190-210x7-190-180-160℃, screw speed 380 rpm, and vacuum -0.60 kg / cm². 2 Polylactic acid composite material was obtained.

[0192] In Examples 1-8 and Comparative Examples 1-3, the aliphatic-aromatic copolyesters were respectively provided by Preparation Examples 1-8 and Comparative Preparation Examples 1-3.

[0193] In Examples 9-11 and Comparative Examples 4-5, the aliphatic-aromatic copolyesters were the aliphatic-aromatic copolyesters provided in Preparation Example 1.

[0194] Among them, the aliphatic polyester is polybutylene succinate, selected from Kingfa Biomaterials Co., Ltd., brand name A200, with a viscosity of 181 mL / g;

[0195] The filler is talc powder, brand name TYT-8875B, with a median particle size D50 of 7-9 μm;

[0196] " / " indicates that the ingredient is not in the formula.

[0197] Table 3

[0198]

[0199] Performance testing

[0200] (1) Gloss: The gloss of the polylactic acid composite materials provided in Examples 1-11 and Comparative Examples 1-5 was tested. According to GB8807-1988 standard, the polylactic acid composite materials were prepared into samples according to the standard requirements and a 20-degree gloss test was performed. Three data points were tested for each sample and the average value was taken.

[0201] (2) Notched Impact Strength of Cantilever Beams: The notched impact strength of the polylactic acid composite materials provided in Examples 1-11 and Comparative Examples 1-5 was tested. According to the ISO 180-2000 test standard, the polylactic acid composite materials were injection molded into test specimens under conditions of 180-185-185-190℃. Five specimens were tested for each sample, and the average value was taken. Among them, "NB" indicates that it did not break.

[0202] (3) Bending performance after aging: The polylactic acid composite materials provided in Examples 1-11 and Comparative Examples 1-5 were used to prepare 3D printing filaments under the following conditions;

[0203] A single-screw extruder with a diameter of 55mm and a die diameter of 4mm was used. The temperature was set at 180℃, the extrusion frequency at 20Hz, and the traction frequency at 25Hz for filament drawing. The 3D printed filament was placed in a constant temperature and humidity aging chamber at 40℃ and 60% humidity for 5 days. After aging, the 3D printed filament was removed, and two experimenters manually performed bending tests until the filament broke. The bending data before breakage was recorded, and the average of the two experimenters' bending test data was taken. Considering testing error, the difference between the two experimenters' bending test data should be less than or equal to 5.

[0204] The specific test results are shown in Table 4.

[0205] Table 4

[0206]

[0207]

[0208] As shown in Table 4, the polylactic acid composite material provided by this invention, by controlling the molar content of aromatic dicarboxylic acids in the aliphatic-aromatic copolyester within a specific range and compounding it with polylactic acid in a specific content, results in a polylactic acid composite material with high gloss and good toughness. The prepared 3D printing filament has a silky luster and good aging resistance, with high bending resistance after aging. The gloss of the polylactic acid composite material is ≥72, and the notched impact strength is ≥6.0 KJ / m. 2 It can withstand ≥36 bends.

[0209] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polylactic acid composite, characterized by, The biodegradable polyester composition comprises 85 to 95 parts by weight of polylactic acid and 5.2 to 13.5 parts by weight of an aliphatic-aromatic copolyester; The aliphatic-aromatic copolyester comprises the following components: Component A: The acid component comprises the following components: a1) 62 to 70 mol% of terephthalic acid or derivatives thereof, or mixtures thereof, based on the total moles of a1) and a2); a2) 30 to 38 mol% of adipic acid or derivatives thereof, or mixtures thereof, based on the total moles of a1) and a2); wherein the total molar percentage content of a1) and a2) is 100 mol%; and, Component B: at least an equimolar amount of 1,4-butanediol to Component A; The acid value of the aliphatic-aromatic copolyester is <1.4 mgKOH / g; The aliphatic-aromatic copolyester further comprises Component C, or further comprises Component C and Component D; The mass percentage content of Component C is 0.01 to 1 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester; The Component C comprises at least one of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic anhydride, 1,2,4,5-benzenetetracarboxylic acid or pyromellitic dianhydride; The mass percentage content of Component D is 0.01 to 1 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester; The Component D is a chain extender with a functionality ≥2, and the chain extender comprises at least one of isocyanate compounds, peroxides, epoxides, oxazoline compounds, oxazine compounds, caprolactam or carbodiimides; The aliphatic-aromatic copolyester has a whiteness index ≥28.

2. The polylactic acid composite of claim 1, wherein The mass percentage content of Component C is 0.05 to 0.9 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester.

3. The polylactic acid composite of claim 2, wherein The mass percentage content of Component C is 0.1 to 0.5 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester.

4. The polylactic acid composite of claim 1, wherein The Component C comprises trimethylolpropane, pentaerythritol or glycerol.

5. The polylactic acid composite of claim 4, wherein The Component C comprises glycerol.

6. The polylactic acid composite of claim 1, wherein The mass percentage content of Component D is 0.05 to 0.8 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester.

7. The polylactic acid composite of claim 6, wherein The mass percentage content of Component D is 0.12 to 0.65 wt% based on 100 wt% of the mass of the aliphatic-aromatic copolyester.

8. The polylactic acid composite of claim 1, wherein The chain extender comprises isocyanate compounds.

9. The polylactic acid composite of claim 1, wherein, The acid value of the aliphatic-aromatic copolyester is <0.90 mgKOH / g.

10. The polylactic acid composite of claim 1, wherein The aliphatic-aromatic copolyester has a whiteness index ≥34.

11. The polylactic acid composite of claim 1, wherein The aliphatic-aromatic copolyester has an intrinsic viscosity of 138 to 272 mL / g.

12. The polylactic acid composite of claim 1, wherein The aliphatic-aromatic copolyester is prepared by the following method, which comprises: (1) reacting Component A with Component B to obtain an esterification product; (2) performing a pre-polycondensation reaction on the esterification product obtained in step (1) to obtain a pre-polycondensation product; (3) performing a polycondensation reaction on the pre-polycondensation product obtained in step (2) to obtain the aliphatic-aromatic copolyester; the molar percentage content of terephthalic acid or derivatives thereof, or mixtures thereof in the component A is 62-70 mol %; The raw material of the reaction in step (1) further comprises a component C.

13. The polylactic acid composite of claim 12, wherein, The viscosity number of the esterification product in step (1) is 12-33 mL / g.

14. The polylactic acid composite of claim 13, wherein, The viscosity number of the esterification product in step (1) is 18-22 mL / g.

15. The polylactic acid composite of claim 12, wherein, The viscosity number of the pre-polycondensation product in step (2) is 33-76 mL / g.

16. The polylactic acid composite of claim 15, wherein, The viscosity number of the pre-polycondensation product in step (2) is 35-50 mL / g.

17. The polylactic acid composite of claim 12, wherein, After the polycondensation reaction, a chain extension reaction is further performed by mixing the polycondensation product with a chain extender.

18. The polylactic acid composite of claim 17, wherein, The viscosity number of the polycondensation product is 138-240 mL / g.

19. The polylactic acid composite of claim 18, wherein, The viscosity number of the polycondensation product is 140.5-144.5 mL / g.

20. The polylactic acid composite of claim 17, wherein, The viscosity number of the product obtained by the chain extension reaction is 150-270 mL / g.

21. The polylactic acid composite of claim 17, wherein, The viscosity number of the product obtained by the chain extension reaction is 180-190 mL / g.

22. The polylactic acid composite of claim 12, wherein, The temperature of the reaction in step (1) is 180-265℃, the pressure is 40-120 KPa, and the time is 2-8 h.

23. The polylactic acid composite of claim 12, wherein, The temperature of the pre-polycondensation reaction in step (2) is 230-270℃; the pressure is 450-3000 Pa; and the time is 2-7 h.

24. The polylactic acid composite of claim 12, wherein, The temperature of the polycondensation reaction in step (3) is 230-270℃; the pressure is 50-600 Pa; and the time is 2-6 h.

25. The polylactic acid composite of claim 17, wherein, The temperature of the chain extension reaction is 180-235℃; and the time is 3-15 min.

26. The polylactic acid composite of claim 1, wherein, The polylactic acid composite further comprises 0-1 parts of an epoxy group-containing copolymer by weight.

27. The polylactic acid composite of claim 26, wherein, The epoxy group-containing copolymer comprises at least one of a copolymer of styrene and acrylate, a copolymer of styrene and methacrylate, or a copolymer of styrene, acrylate, and methacrylate.

28. The polylactic acid composite of claim 1, wherein, The melting point of the polylactic acid is 140-180℃.

29. The polylactic acid composite of claim 1, wherein, The mass content of the D-form of the polylactic acid is 0.3-4.8%.

30. The polylactic acid composite of claim 1, wherein, The glossiness of the polylactic acid composite is ≥72.

31. The polylactic acid composite of claim 30, wherein, The glossiness of the polylactic acid composite is ≥81.

32. The polylactic acid composite of claim 31, wherein, The glossiness of the polylactic acid composite is ≥90.

33. The polylactic acid composite of claim 1, wherein, The cantilever beam notched impact strength of the polylactic acid composite is ≥6.0 KJ / m 2 .

34. The polylactic acid composite of claim 33, wherein, The cantilever beam notched impact strength of the polylactic acid composite is ≥8.9 KJ / m 2 .

35. A 3D printing material, characterized in that, The 3D printing material comprises the polylactic acid composite according to any one of claims 1-34.

36. The 3D printing material of claim 35, wherein, The 3D printing material comprises a 3D printing wire.

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