CN1793228A - Process for preparing complete biological degradation high flexible polyalctic material - Google Patents

Abstract

The invention relates to a preparation method of a completely biodegradable high-toughness polylactic acid material. The plasticized polylactic acid system was obtained by using small molecule polyol esters, oligomeric polyesters and citrate plasticizers. Crosslinking is introduced into the plasticized polylactic acid system by electron beam or γ-ray irradiation crosslinking method to obtain high toughness polylactic acid material with stable structure and performance. The plasticized polylactic acid system contains 40 to 95 parts of polylactic acid; 5 to 59.5 parts of compound plasticizer; 0.5 to 5 parts of crosslinking agent; 0 to 1 part of smoothing agent; 0 to 30 parts of inorganic Filler; electron beam or gamma ray irradiation dose is 3-30Mrad. It is processed by extrusion, blow molding, casting, molding, injection molding and other melt blending methods or by solution blending and casting methods. The polylactic acid material with high toughness can be obtained by cross-linking the formed polylactic acid material under the irradiation of electron beams. It has a wide range of applications in packaging, protection, toys and other applications.

Description

Preparation method of completely biodegradable high-toughness polylactic acid material

technical field

The invention belongs to a preparation method of a completely biodegradable high-toughness polylactic acid material.

Background technique

The rapid development of science and technology has led to the rapid development of polymer materials, which have now become the most widely used materials. However, a large amount of waste after use is difficult to degrade in the natural environment, causing increasingly serious pollution to the natural environment. This not only affects people's daily life, but also brings great harm to the national economy and industrial and agricultural production. In recent years, with the enhancement of people's awareness of environmental protection, the development of degradable materials is an important way to solve the problem of environmental pollution. Therefore, countries all over the world pay more and more attention to fully biodegradable polymer materials.

Polylactic acid is a completely biodegradable polymer material, which is finally degraded into inorganic substances such as water and carbon dioxide in the natural environment through the action of enzymes produced by microorganisms. Among the degradable thermoplastic polyester polymer materials, polylactic acid has the highest melting point, the highest glass transition temperature and mechanical strength, so it has better heat resistance. However, polylactic acid has disadvantages such as poor toughness, narrow processing temperature range, and high cost of raw materials, and its application in applications requiring softness is limited. The toughness of polylactic acid can be greatly improved by blending with plasticizers, especially for processing and reducing costs. The plasticized polylactic acid can be processed by various methods such as extrusion, injection molding, casting, blow molding, spinning, and biaxial stretching. It is expected that this high-toughness fully biodegradable polylactic acid material will have a wide range of applications in packaging, protection, toys and other applications.

Chinese patent CN 1367189 A uses free radical grafting to graft polyvinyl alcohol, acrylic acid, etc. onto the main chain of polylactic acid, which significantly improves the flexibility of polylactic acid. This method belongs to chemical modification, and has disadvantages such as complex process and high cost. Chinese patent CN 00112783.7 relates to a plasticized polylactic acid material used in medical anti-adhesion films, the plasticizers used in this material include water-soluble plasticizers such as polyethylene glycol and oil-soluble plasticizers such as oleic acid and stearin acid, capric acid, ethyl oleate. Chinese patent CN02123145.1 relates to a biodegradable plastic product containing 5-50% by weight of polyglycerol acetate plasticized polylactic acid. Chinese patent CN 03117482.5 relates to a polylactic acid composition film containing 2-15% medical plasticizer, the plasticizer used is polyethylene glycol, tributyl citrate, acetyl tributyl citrate, oligomeric polylactic acid . The plasticizing effects of polyol esters and polyester plasticizers on polylactic acid have their own advantages and disadvantages in terms of heat resistance, migration resistance, compatibility, etc., but the effect of using them alone is not satisfactory. Chinese patent CN200410011366.5 relates to a composite plasticizer containing two or more types of polyol esters, oligomeric polyesters and citrate plasticizers, which improves the comprehensive performance of polylactic acid.

The technical key of the plasticized system of high toughness polylactic acid lies in the stability of the system, including the stability of structure and performance. In the polylactic acid plasticized system with high plasticizer content, the plasticizer will precipitate over time, and the strength and heat resistance of the plasticized polylactic acid material cannot meet the requirements in some application fields. If electron beam or γ-ray irradiation is introduced into the polylactic acid plasticization system to make polylactic acid cross-linked, it will not only fix a large amount of plasticizer in the system, not affect the complete biodegradability of the material, but also improve the strength of the material And heat resistance, so as to obtain a completely biodegradable high-toughness polylactic acid material.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a high-toughness polylactic acid material with stable structure and performance.

The invention adopts small molecule polyol esters, oligomeric polyesters and citrate plasticizers to obtain plasticized polylactic acid system. The irradiation cross-linking method is used to introduce cross-linking into the plasticized polylactic acid system to obtain a high-toughness polylactic acid material with stable structure and performance.

The steps and conditions of the preparation method of the fully biodegradable high-toughness polylactic acid material of the present invention are as follows:

The raw materials are:

Polylactic acid is: crystalline polylactic acid or non-crystalline polylactic acid;

The plasticizer is: one or more compounds selected from polyol esters, citric acid esters or polyesters;

The crosslinking agent is selected from triallyl isocyanurate, trimethyl isocyanurate, trimethylolpropane trimethacrylate or (1,6-hexanediol) dimethacrylate functional group monomer;

The slip agent is aliphatic amide, oleic acid amide or erucic acid amide; the inorganic filler is silicon dioxide, titanium dioxide, diatomaceous earth, carbon black, calcium carbonate or talcum powder;

The ratio of raw materials by weight is: polylactic acid: 40-95 parts; compound plasticizer: 5-59.5 parts; cross-linking agent: 0.5-5 parts; slip agent: 0-1 part; inorganic filler: 0-30 parts share;

Preparation steps and conditions are:

Weigh the raw materials according to the ratio, and process them by melt blending methods such as extrusion, blow molding, casting, molding or injection molding; or process them by solution blending casting methods, and use acetone, chloroform or a mixed solvent of the two as the solvent ; The formed polylactic acid material is cross-linked under electron beam irradiation, and the irradiation dose of electron beam or gamma ray is 3-30Mrad, and a completely biodegradable high-toughness polylactic acid material can be obtained.

Beneficial effects of the invention:

The method of the invention provides a preparation method of a high-toughness polylactic acid material with stable structure and performance. The polylactic acid material prepared by the method has high breaking elongation on the basis of maintaining a certain tensile strength, and the obtained material has stable properties. Through the thermogravimetric experiment, it can be found that with the increase of the irradiation dose and the increase of the crosslink density, the filler added to the polylactic acid has a higher thermal decomposition temperature and better thermal stability; It can be seen from the long-term aging experiment that the additives in the prepared materials have migration resistance, and it is not easy to precipitate out of the material surface. Through the above, the material prepared by the present invention has better long-term service performance.

Detailed ways:

Example 1: 40 parts by weight of polylactic acid, 12 parts by weight of glyceryl triacetate, 45 parts by weight of poly-1.3-butylene adipate and 3 parts by weight of triallyl isocyanurate are dissolved in chloroform solvent , and stir to obtain a mixed solution. Then the solvent in the mixed solution is volatilized to obtain plasticized polylactic acid. The dried plasticized polylactic acid is melted and molded, and then the molded sample is cross-linked under an electron beam irradiation dose of 30Mrad to obtain a completely biodegradable high-toughness polylactic acid material.

Embodiment 2: The preparation method is the same as in Example 1, and the material composition is: 60 parts by weight of polylactic acid, 20 parts by weight of glyceryl triacetate, 17 parts by weight of poly-1.3-butylene adipate and 3 parts by weight of triallyl isocyanurate. The irradiation dose is 10 Mrad.

Embodiment 3: The preparation method is the same as in Example 1, and the material composition is: 90 parts by weight of polylactic acid, 20 parts by weight of glyceryl triacetate, 15 parts by weight of poly-1.3-butylene adipate and 5 parts by weight of triallyl isocyanurate. The irradiation dose is 20 Mrad.

Example 4: Add 90 parts by weight of polylactic acid, 5 parts by weight of acetyl tri-n-butyl citrate, 4.5 parts by weight of calcium carbonate, and 0.5 parts by weight of trimethylisourea cyanate into the chloroform solvent, stir and mix to obtain a mixed solution middle. Then the solvent in the mixed solution is volatilized to obtain plasticized polylactic acid. The dried plasticized polylactic acid is melted and molded, and then the molded sample is cross-linked under an electron beam irradiation dose of 10 Mrad to obtain a completely biodegradable high-toughness polylactic acid material.

Example 5: 60 parts by weight of polylactic acid, 10 parts by weight of triethyl citrate, 15 parts by weight of 1.3-butylene adipate, 13 parts by weight of titanium dioxide and 2 parts by weight of trimethylolpropane trimethyl Acrylate-based melt extrusion molding or processing by blow molding, casting, molding, injection molding and other methods. The molded sample is cross-linked at an electron beam irradiation dose of 15 Mrad to obtain a completely biodegradable high-toughness polylactic acid material.

Embodiment 6: 80 parts by weight of polylactic acid, 10 parts by weight of polyethylene glycol, 8 parts by weight of acetyl triethyl citrate, and 2 parts by weight of dimethacrylate (1,6-hexanediol) ester are melt-extruded Or use methods such as extrusion, blow molding, casting, molding, injection molding to carry out processing and molding. The molded sample is cross-linked under an electron beam irradiation dose of 10 Mrad, and a completely biodegradable high-toughness polylactic acid material can be obtained.

Embodiment 7: preparation method is the same as embodiment 6, and material is composed of: 40 parts by weight of polylactic acid, 31 parts by weight of polyethylene glycol, 25 parts by weight of acetyl triethyl citrate, 4 parts by weight of dimethacrylic acid (1,6 -hexanediol), the irradiation dose is 4Mrad.

Embodiment 8: 40 parts by weight of polylactic acid, 10 parts by weight of acetyl triethyl citrate, 45 parts by weight of poly 1.3-butylene sebacate and 5 parts by weight of triallyl isocyanurate are dissolved in chloroform solvent, stir and mix to obtain a mixed solution. Then the solvent in the mixed solution is volatilized to obtain plasticized polylactic acid. The dried plasticized polylactic acid is melted and molded, and then the molded sample is cross-linked under an electron beam irradiation dose of 30Mrad to obtain a completely biodegradable high-toughness polylactic acid material.

Embodiment 9: The preparation method is the same as Example 8, and the material consists of: 60 parts by weight of polylactic acid, 20 parts by weight of polyethylene glycol, 15 parts by weight of acetyl triethyl citrate, 5 parts by weight of dimethacrylic acid (1,6 -hexanediol), the irradiation dose is 6Mrad.

Embodiment 10: The preparation method is the same as Example 8, and the material consists of: 90 parts by weight of polylactic acid, 4.5 parts by weight of polyethylene glycol, 4.5 parts by weight of acetyl triethyl citrate, 1 part by weight of dimethacrylic acid (1,6 -hexanediol), the irradiation dose is 3Mrad.

Claims (1)

1. the preparation method of a complete biological degradation high flexible polyalctic material is characterized in that:

Starting material are:

Poly(lactic acid) is: crystalline polylactic acid or amorphism poly(lactic acid);

Softening agent is: the compound that is selected from polyol ester class, citric acid ester type or wherein one or two or more kinds of polyester;

Linking agent is selected from cyanacrylate, trimethylammonium isocyanuric acid ester, trimethylolpropane trimethacrylate or 1,6-hexanediol dimethacrylate polyfunctional monomer;

Described slipping agent is aliphatic amide, amine hydroxybenzene or erucicamide; Mineral filler is silicon-dioxide, titanium dioxide, diatomite, carbon black, lime carbonate or talcum powder;

Raw-material weight per-cent proportioning is: poly(lactic acid): 40～95 parts; Composite softening agent: 5～59.5 parts; Linking agent: 0.5～5 part; Slipping agent: 0～1 part; Mineral filler: 0～30 part;

Preparation process and condition are:

According to the proportioning weighing raw materials, adopt extrude, melt-mixing method such as blowing, curtain coating, mold pressing or injection moulding carry out machine-shaping; Or adopting the machine-shaping of solution blending casting process, solvent is selected acetone, chloroform or both mixed solvents for use; Poly-lactic acid material after the moulding is carried out crosslinked under the irradiation of electron beam, electron beam or gamma-ray irradiation dosage are 3～30Mrad, can obtain complete biological degradation high flexible polyalctic material.