34 results about "Polylactic acid preparation" patented technology

The present invention discloses a multi-stage polymerization method for polylactic acid preparation by ring-opening polymerization of lactide, the method is as follows: molten L-lactide and a composite catalyst system are fully mixed in a ring-type static mixing reaction device comprising a corrugated plate type static mixer, the reaction device temperature is raised for initial ring-opening polymerization, then the reaction device temperature is further raised for L-polylactic acid preparation. According to the multi-stage polymerization method, by adjusting of temperature and reaction time of different stages and adjusting of reaction system flow rate and shear rate, high optical purity and molecular weight polylactic acid with the distribution meeting the requirements of spinning can be obtained. Compared with the conventional polymerization method, the multi-stage polymerization method has the advantages of simple polymerization equipment, low energy consumption, low investment, short reaction time, controllable product properties, high production magnification degree and the like.

The invention discloses a method for preparing a high molecular weight vertical structure composite polylactic acid with melt stability characteristics. The method comprises the following steps: firstly, carrying out drying treatment on L-polylactide and dextral polylactic acid in vacuum, and then mixing an initiator which can be completely dissolved into absolute ethyl alcohol with a cross-linking agent, and then adding a mixture to a fusion mixer; melting and blending under the conditions that the temperature is 170-200 DEG C and the rotating speed is 20-120 rpm (revolutions per minute) for 2-15 minutes. The prepared high molecular weight vertical structure composite polylactic acid not only has excellent melt stability, but also has strong recrystallization ability, and can ensure that the vertical structure composite polylactic acid crystal with high purity and high content is reformed in a molten product, so as to provide excellent heat resistance and weather fastness to the product. The possibility is also provided for preparation of a PLA product with high performance by virtue of a melt processing technology. Meanwhile, the preparation method provided by the invention is simple in process, high in efficiency, and easy for realization of large-scale industrial production.

The invention provides a polylactic acid segmented copolymer and modified polylactic acid preparation method. The method includes: reacting branched polyactic acid with halogenated acid halide to obtain macroinitiator to further react with glycidyl methacrylate to obtain the polylactic acid segmented copolymer; and finally, blending the branched polyactic acid, the polylactic acid segmented copolymer and polylactic acid to obtain the modified polylactic acid. Compared with the prior art which using bis-glycidyl ester for modifying the polylactic acid, the method has the advantages that firstly, the polylactic acid-polyglycidyl methacrylate segmented copolymer is a macromolecular compound and can be in cross-linking reaction with the branched polylactic acid and the polylactic acid to form polymer with higher molecular weight and higher branching degree, so that the problems of proneness to migration and osmosis of micromolecular branched cross-linking agent are solved, and stability of the modified polylactic acid is improved; and secondly, the polylactic acid-polyglycidyl methacrylate segmented copolymer with an intrinsic branched polylactic acid structure unit has high compatibility to the branched polylactic acid and the polylactic acid.

The invention provides a preparation method of polylactic acid with low optical purity and high molecular weight. The method comprises the following steps: enabling lactide, to be subjected to isomerization reaction under the catalysis of alcohol alkali metal salt, so as to obtain isomer mixture of meso-lactide, D-lactide and L-lactide, wherein the optical purity of L-lactide or D-lactide in lactide is 90 to 100 percent; enabling the mixture to be subjected to polymerization reaction, so as to obtain the polylactic acid with low optical purity and high molecular weight. The preparation method is simple in process route and easy to operate; the polylactic acid prepared is low in optical purity. The weight-average molecular weight of the polylactic acid prepared through the preparation method is 90 to 120 kg / mol, the molecular weight distribution index is 1.3 to 1.7, the glass-transition temperature is 53 to 57 DEG C, and the optical rotation is -125 to 120 degrees.

A preparation method of biodegradable polyesteramide modified polylactic acid belongs to the technical field of polylactic acid. The method adopting a polycondensation-chain extension technology to prepare aliphatic polyesteramide modified polylactic acid comprises the following steps: carrying out melt polycondensation on aliphatic short-chain polyamide diacid and polyether diol to prepare a polyesteramide prepolymer, polycondensing the polyesteramide prepolymer, and a polylactic acid prepolymer, and carrying out chain extension by using diacylbislactame and bisoxazoline chain extender to prepare the biodegradable polyesteramide modified polylactic acid product with the molecular weight of 90290-111820. The method has the advantages of mild conditions, cheap and easily available raw materials, and environmental protection.

A polyepoxysuccinic acid derivative scale inhibitor, said method comprising: cyclization reaction and purification of cyclization products; preparation of polyepoxysuccinic acid products; also includes preparation of polyepoxysuccinic acid derivative Lcys-PESA , the preparation method is: put the product of polyepoxysuccinic acid PESA into a three-necked flask, add L-cysteine, put it into a methyl silicone oil bath and heat it, and when the temperature rises to 110°C-120°C, start Adjust the pH value, fully stir the reaction, and dry with a drying device to obtain L-cysteine-modified polyepoxysuccinic acid derivatives, which are finely ground and sealed for future use. The polyepoxysuccinic acid derivative scale inhibitor is applied at a temperature of 55°C-85°C, a pH value of 5.0-10.0, and a scale inhibition rate of 90%-98%. A small molecular substance is added in the synthesis, which does not contain phosphorus, is non-toxic, does not damage the ecological environment, and has good biodegradability and water solubility. Its excellent scale inhibition and dispersion properties are especially suitable for industrial water treatment.

The invention discloses a preparation method of reinforced and toughened polylactic acid. The preparation method is characterized in that during the processing process, the crystallized morphology of the polylactic acid is controlled so as to improve the mechanical property of the polylactic acid. Particularly, during the processing process, certain shearing force fields and certain bidirectional drawing force fields are applied on a polylactic acid melt in different directions through the control of the number and the type of force assembling units, when the shearing and drawing action force is large enough, polylactic acid molecules are directionally arranged in the force field direction at first to form shish, then polylactic acid lamellar crystals are arranged in a direction perpendicular to the shish, and at least, an shish-kebab crystallization structure is formed; and the sizes of crystalline grains are small, besides, a large amount of interfaces are introduced in a polylactic acid material, so that the strength and the toughness of the polylactic acid material are remarkably improved. The more the number of the force assembling units with higher melt deformation degrees is, the higher the strength of the bidirectional drawing force field in the direction perpendicular to the extrusion direction is, and the smaller the mechanical strength difference of the prepared polylactic acid product in the extrusion direction and the direction perpendicular to the extrusion direction is. The preparation method has the advantages that the force assembling units are additionally arranged on a traditional extrusion device, the preparation method is simple in operation, can be produced continuously, is convenient to control, stable in quality, and high in production efficiency, has a good industrial and market prospect, can be widely applied to the preparation of a polylactic acid plate, a polylactic acid sheet and a polylactic acid film material, with high strength and toughness.

The invention discloses a method for preparing high-efficient gel-free long-chain branching polylactic acid, and belongs to the technical field of high-performance polymer preparation. According to the method, metallic oxide nano particles are adopted as an accelerating agent, and the coordination between the ester group of macro molecular polylactic acid and the metallic oxide nano particle and between the ester group of a small molecular ester monomer and the metallic oxide nano particle is utilized to activate the ester groups, so that the ester exchange reaction between a polyfunctional small molecular ester monomer and a macro molecular polylactic acid is promoted to prepare the long-chain branching polylactic acid with high melt strength and significant strain hardening characteristics. The result reveals that the melt strength of the polylactic acid is increased by many folds by means of the method, the melt strength can be improved up to thirty folds, the gel content is zero, the adopted metallic oxide nano particles and the polyfunctional ester monomer are environmentally friendly, free from toxin and pollution, the source of the polyfunctional ester monomer is extensive,and most of the polyfunctional ester monomers can be used in food related industries, so that the method is a high-efficient, environmental-friendly and gel-free long-chain branching polylactic acid preparation method.

The invention relates to the technical field of polylactic acid preparation. The invention discloses a polylactic acid polymerization reaction device and system. The polylactic acid polymerization reaction device comprises a polymerization reactor (10) and a stirring assembly (20) arranged in a flow channel of the polymerization reactor (10), the stirring assembly (20) comprises an electromagneticwinding mechanism and a magnetic induction piece (21); the electromagnetic winding mechanism is arranged around the inner wall of the polymerization reactor (10); the electromagnetic winding mechanism is arranged around the magnetic induction piece (21), and a gap is formed between the electromagnetic winding mechanism and the magnetic induction piece (21), so that the magnetic induction piece (21) and the electromagnetic winding mechanism can generate electromagnetic induction, the magnetic induction piece (21) rotates around the axis of the magnetic induction piece (21), and a threaded groove is formed in the magnetic induction piece (21). According to the polylactic acid polymerization reaction device provided by the invention, the polymerization reaction effect can be improved, so that the conversion rate of a product is improved.