Method for accelerating crystallization of polylactic acid resin

Abstract

The invention relates to the technical field of polylactic acid modification and aims to provide a method for accelerating crystallization of polylactic acid resin. The method comprises the specific steps of: adding a semi-crystalline polylactic acid resin and a polymer-type crystallization promoter into a mixing apparatus; then mixing well in the mixing apparatus; and extruding for granulation, so as to obtain a rapid crystallization modification polylactic acid resin. The method employs organic high-molecular polymer-type crystallization promoter to improve crystallization performance of the polylactic acid, and the promoter has good compatibility with polylactic acid, improves nucleation effect, accelerates crystallization of polylactic acid, and improves processability and thermal behavior of the polylactic acid. Furthermore, a commercialized semi-crystalline polymer polyvinylidene fluoride having similar melting point as polylactic acid is used as the crystallization promoter for polylactic acid, and a melt blending method can be employed. The method provided by the invention has simple process, low cost and can realize large-scale industrialized production.

Description

technical field

[0001] The invention relates to the technical field of polylactic acid modification, in particular to a method for accelerating the crystallization of polylactic acid resin. Background technique

[0002] With the deteriorating environmental and energy problems such as global warming, "white pollution" of plastic waste, and increasingly scarce fossil resources, bio-based and biodegradable polymer materials have attracted more and more attention. Polylactic acid is a thermoplastic polymer material made from biomass renewable resources. It gets rid of the dependence on petroleum resources, and the environmental load caused by the manufacturing process is small. It has good compostability and biodegradability. The carbon dioxide and water produced by degradation can be returned to nature and rejoined in the photosynthesis process of plants, thus maintaining the balance of the carbon cycle on the earth. Polylactic acid has good mechanical properties, similar to p...

Examples

preparation example Construction

[0019] The preparation method of the semi-crystalline polylactic acid resin is not particularly limited, for example, polylactic acid can be obtained by ring-opening polymerization of L, L-type, D, L-type lactide, L-type, D-type or racemic lactic acid Polylactic acid is obtained by direct polycondensation, and polylactic acid is obtained by three-dimensional crosslinking of polylactic acid by light, heat, radiation, and crosslinking agents. Semi-crystalline polylactic acid resin can also use known inorganic fillers, fillers, and flame retardants. In addition to the above-mentioned components, well-known plasticizers, heat stabilizers, light stabilizers, antioxidants, and anti-hydrolysis agents can also be used together. , internal and external lubricants, impact modifiers, antistatic agents, colorants, release agents, foaming agents, pigments, antibacterial and anti-enzyme agents, coupling agents, other fillers, other nucleating agents, and general synthetic resins Auxiliaries...

Embodiment 1

[0022] Embodiment 1: the preparation of pure polylactic acid spline

[0023] 100 parts of vacuum-dried semi-crystalline poly-L-lactic acid (Shimazu company 9020 grade, containing about 1.5% of D configuration, weight average molecular weight of 186,000) were extruded in a twin-screw extruder at 190 °C, drawn into strands, and Cool in the air and granulate.

[0024] Test of crystallization speed: use DSC test, nitrogen atmosphere. In the non-isothermal DSC test, the sample was heated from room temperature to 190 °C at 100 °C / min, kept for 2 min to eliminate thermal history, cooled to 30 °C at 10 °C / min, kept at 30 °C for 2 min, and then heated at 10 °C / min to 190°C. In the isothermal DSC analysis, the sample was heated from room temperature to 190 °C at 100 °C / min, kept for 2 min to eliminate thermal history, rapidly cooled to 120 °C at 100 °C / min, kept for 60 min, and then raised to 10 °C / min 190°C.

[0025] The crystallinity during cooling at 10 °C / min was calculated fro...

Embodiment 2

[0027] Vacuum-dried semi-crystalline poly-L-lactic acid (Shimazu company's 9020 grade, containing about 1.5% of the D configuration, with a weight average molecular weight of 186,000) 99 parts and PVDF (Wu Yu Chemical Company, KF850 grade) 1 part at 190 °C Extrude in a twin-screw extruder, draw strands, cool in air, and pelletize. The calculated crystallization kinetics and thermal performance parameters are shown in Table 1.

technical field

[0001] The invention relates to the technical field of polylactic acid modification, in particular to a method for accelerating the crystallization of polylactic acid resin. Background technique

[0002] With the deteriorating environmental and energy problems such as global warming, "white pollution" of plastic waste, and increasingly scarce fossil resources, bio-based and biodegradable polymer materials have attracted more and more attention. Polylactic acid is a thermoplastic polymer material made from biomass renewable resources. It gets rid of the dependence on petroleum resources, and the environmental load caused by the manufacturing process is small. It has good compostability and biodegradability. The carbon dioxide and water produced by degradation can be returned to nature and rejoined in the photosynthesis process of plants, thus maintaining the balance of the carbon cycle on the earth. Polylactic acid has good mechanical properties, similar to p...

Examples

preparation example Construction

[0019] The preparation method of the semi-crystalline polylactic acid resin is not particularly limited, for example, polylactic acid can be obtained by ring-opening polymerization of L, L-type, D, L-type lactide, L-type, D-type or racemic lactic acid Polylactic acid is obtained by direct polycondensation, and polylactic acid is obtained by three-dimensional crosslinking of polylactic acid by light, heat, radiation, and crosslinking agents. Semi-crystalline polylactic acid resin can also use known inorganic fillers, fillers, and flame retardants. In addition to the above-mentioned components, well-known plasticizers, heat stabilizers, light stabilizers, antioxidants, and anti-hydrolysis agents can also be used together. , internal and external lubricants, impact modifiers, antistatic agents, colorants, release agents, foaming agents, pigments, antibacterial and anti-enzyme agents, coupling agents, other fillers, other nucleating agents, and general synthetic resins Auxiliaries...

Embodiment 1

[0022] Embodiment 1: the preparation of pure polylactic acid spline

[0023] 100 parts of vacuum-dried semi-crystalline poly-L-lactic acid (Shimazu company 9020 grade, containing about 1.5% of D configuration, weight average molecular weight of 186,000) were extruded in a twin-screw extruder at 190 °C, drawn into strands, and Cool in the air and granulate.

[0024] Test of crystallization speed: use DSC test, nitrogen atmosphere. In the non-isothermal DSC test, the sample was heated from room temperature to 190 °C at 100 °C / min, kept for 2 min to eliminate thermal history, cooled to 30 °C at 10 °C / min, kept at 30 °C for 2 min, and then heated at 10 °C / min to 190°C. In the isothermal DSC analysis, the sample was heated from room temperature to 190 °C at 100 °C / min, kept for 2 min to eliminate thermal history, rapidly cooled to 120 °C at 100 °C / min, kept for 60 min, and then raised to 10 °C / min 190°C.

[0025] The crystallinity during cooling at 10 °C / min was calculated fro...

Embodiment 2

[0027] Vacuum-dried semi-crystalline poly-L-lactic acid (Shimazu company's 9020 grade, containing about 1.5% of the D configuration, with a weight average molecular weight of 186,000) 99 parts and PVDF (Wu Yu Chemical Company, KF850 grade) 1 part at 190 °C Extrude in a twin-screw extruder, draw strands, cool in air, and pelletize. The calculated crystallization kinetics and thermal performance parameters are shown in Table 1.

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