CN115895216A - A kind of polylactic acid material and its preparation method and product - Google Patents

Abstract

The application provides a polylactic acid material and a preparation method and a product thereof, wherein the polylactic acid material comprises the following raw material components in parts by mass: polylactic acid: 100 parts of (A); organic nucleating agent: 0.1-2 parts; inorganic nucleating agent: 1-20 parts; wherein the polylactic acid is prepared from the following components in percentage by mass of 10: 0.1-2 parts of poly (L-lactic acid) and poly (D-lactic acid). PDLA, an organic nucleating agent and an inorganic nucleating agent are compounded in PLLA, and the crystallization nucleation density of the polylactic acid material is increased, so that the size and the size distribution of spherulites are obviously reduced, and the crystallinity of the polylactic acid is greatly improved. The polylactic acid material obtained by the method has good heat resistance and toughness.

Description

A kind of polylactic acid material and its preparation method and product

technical field

The present application relates to the technical field of polymer materials, in particular to a polylactic acid material and its preparation method and product.

Background technique

Polylactic acid is a completely biodegradable aliphatic polymer obtained from crops such as cornstarch, sugarcane, sugar beet, etc., from which starch, cellulose, etc. are extracted, hydrolyzed and saccharified, fermented, and polymerized by chemical methods. Important and commercially available biopolymers derived from renewable resources.

However, the heat resistance and toughness of polylactic acid materials in the prior art are poor, which limits its further application.

Therefore, it is necessary to provide a polylactic acid material with good heat resistance and toughness.

Contents of the invention

The application provides a polylactic acid material and its preparation method and products. The polylactic acid material has good heat resistance and toughness, which expands the application range of the polylactic acid material, and the preparation method of the material is simple. Using the material can obtain The products are not easily deformed by heat and are not easy to break.

In the first aspect, the application provides a polylactic acid material, which includes the following raw material components in parts by mass:

Polylactic acid: 100 parts;

Organic nucleating agent: 0.1 to 2 parts;

Inorganic nucleating agent: 1-20 parts;

Wherein, the polylactic acid is a mixture of poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA) with a mass ratio of 10:0.1-2.

In the technical scheme of the present application, PDLA, organic nucleating agent and inorganic nucleating agent are used in PLLA to increase the crystallization nucleation density of polylactic acid materials, and provide a large number of heterogeneous nucleation points for PLLA crystallization, which can be used in Thermodynamically stable crystal nuclei are rapidly formed at higher temperatures, and the crystal nuclei grow rapidly, shortening the crystallization induction period of polylactic acid materials, accelerating the growth rate of polylactic acid spherulites, increasing the number of spherulites instantly and rapidly increasing the crystallization rate in a limited space , so that the size and size distribution of spherulites are significantly reduced, and the crystallinity of polylactic acid is greatly improved. The resulting polylactic acid material has good heat resistance and toughness.

In some embodiments of the present application, the organic nucleating agent includes sodium benzoate, hydroxyapatite, sodium lignosulfonate, zinc phenylphosphonate, aromatic sulfonate derivatives, rare earth β crystal nucleation One or more of the aramid-type β-nucleating agent, sebacic acid dibenzohydrazide and polyamide compounds; and/or

The inorganic nucleating agent includes one or more of modified talcum powder, nano-modified montmorillonite, and nano-titanium dioxide,

Wherein, in the modified talc powder, the particle size D50=0.5-1.5 μm, D98≤6 μm, the content of silicon dioxide ≥60 wt%, the content of magnesium oxide is 30-35 wt%,

The nano-modified montmorillonite is an organic montmorillonite modified by double long-chain alkyl ammonium, and the interlayer spacing is ≥3.5nm,

The nano-titanium dioxide is rutile-type titanium dioxide with an average particle diameter of 30-60nm.

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Polybutylene succinate: 1 to 60 parts.

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Polyhydroxyalkanoate: 1 to 50 parts.

The polyhydroxyalkanoate includes poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxycaproate) and poly(3-hydroxybutyrate-co-3-hydroxycaproate) One or more of hydroxybutyrate-co-4-hydroxybutyrate).

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Compatibility and toughening agent: 0.02 to 15 parts; said compatibilization and toughening agent includes vinyl acetate copolymer, vinyl acetate-ethylene copolymer, ethylene-n-butyl acrylate-glycidyl methacrylate terpolymer , ethylene-methacrylic acid-glycidyl methacrylate, butyl acrylate-methyl methacrylate core-shell structure copolymer, methyl methacrylate-butadiene-styrene terpolymer, diperoxide One or more of cumene.

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Plasticizer: 0.5 to 4 parts; the plasticizer includes acetylated monoglyceride fatty acid ester, epoxidized soybean oil, acetyl tributyl citrate, tributyl citrate, dioctyl adipate, Glycerin, Sorbitol, Pentaerythritol, Dipentaerythritol, Macrogol-500, Macrogol-1500, Macrogol-2000, Macrogol-3000, Macrogol-4000, Polyethylene Glycol - one or more of 6000; and/or

Chain extender: 0.1 to 0.6 parts; the chain extender is styrene-methyl acrylate-glycidyl methacrylate terpolymer; and/or

Filler: 3 to 15 parts; the filler is light active nano-calcium carbonate; and/or

Lubricant: 0.1-0.8 parts; the lubricant includes one or more of ethylene bis stearic acid amide, pentaerythritol stearate, erucic acid amide, oleic acid amide, stearic acid, and zinc stearate ;and / or

Dispersant: 0.1-0.5 parts; the dispersant is one or more of ethylene acrylic acid copolymer, 26# food-grade white mineral oil, low-density polyethylene wax, and oxidized low-density polyethylene wax.

In a second aspect, the present application also provides a method for preparing a polylactic acid material, comprising the following steps:

According to any embodiment of the first aspect, the raw material components of the polylactic acid material are mixed uniformly and then extruded to obtain the polylactic acid material.

In the technical solution of the present application, since the raw material components of the polylactic acid material in any embodiment of the first aspect have good compatibility, it is only necessary to simply blend and extrude each raw material component to have good heat resistance The material is tough and tough, and the preparation method is simple, which is suitable for industrial production.

In some embodiments of the present application, the following steps are specifically included:

Drying the poly-D-lactic acid, poly-L-lactic acid, polybutylene succinate, and polyhydroxyalkanoate;

Drying poly-D-lactic acid, poly-L-lactic acid, polybutylene succinate, polyhydroxyalkanoate and the inorganic nucleating agent, organic nucleating agent, filler, dispersant, lubricant, chain extender The polylactic acid material is obtained by uniformly mixing and extruding granulating agent, compatibilizing and toughening agent and plasticizer.

In some embodiments of the present application, the extrusion granulation specifically includes:

Extrusion and granulation are carried out in a twin-screw extruder; wherein, the processing temperature range of the twin-screw extruder is 105-195°C, and each heating section of the twin-screw extruder gradually increases from 105°C to 195°C, and the twin-screw extruder The speed is 100-350r/min, the residence time of the material in the twin-screw extruder is less than 5min, and the length-to-diameter ratio of the screw is 36-52.

In the third aspect, the present application also provides a polylactic acid product, which is obtained by processing the polylactic acid material according to any embodiment of the first aspect or the second aspect.

In the technical solution of the present application, since the polylactic acid material in any embodiment of the first aspect or the second aspect has good heat resistance and toughness, the polylactic acid material has good processability, and can obtain heat-resistant deformation. It is a polylactic acid product that is not easy to break, and at the same time, the product has good biodegradability and is green and environmentally friendly.

In the fourth aspect, the present application also provides a method for preparing polylactic acid products, comprising the following steps:

Use the polylactic acid material described in any embodiment according to any embodiment of the first aspect or the second aspect to obtain a polylactic acid product through hot molding or cold molding in a blister machine.

In the technical solution of the present application, since the crystallization induction period of the polylactic acid material in any embodiment of the first aspect or the second aspect is short, different blister molding processes can be used to obtain polylactic acid products with good performance. The spherulite growth rate of lactic acid material is fast, which can shorten the blister molding cycle and achieve the purpose of reducing cost and improving efficiency.

Detailed ways

Each embodiment or implementation in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

In the description of this specification, descriptions that refer to the terms "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific examples", or "some examples" etc. Specific features, structures, materials, or characteristics described in or examples are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

The inventors found that although polylactic acid materials in the prior art have good biodegradability, are environmentally friendly and have high safety, they can be used in food and drug packaging. However, the heat resistance of polylactic acid materials is very poor, and its heat resistance performance depends on its crystallinity and crystallization behavior. Since polylactic acid is a semi-crystalline polymer, it has crystallization ability, but the crystallization rate is slow. Traditional molding processes, such as Extrusion and injection molding all involve rapid cooling of the melt during the molding process, so that usually only polylactic acid products with low crystallinity can be obtained. For polylactic acid products with very low crystallinity, most of the amorphous part belongs to the active amorphous region. Once the ambient temperature is close to the glass transition temperature, the chain segments will obtain higher mobility, and the macroscopic performance is the product. out of shape. The glass transition temperature of polylactic acid is around 60°C, which also determines that the heat-resistant temperature of ordinary polylactic acid products is also around this temperature.

In this regard, in order to expand its application range, it is necessary to provide a polylactic acid material with good heat resistance and toughness.

In the first aspect, the application provides a polylactic acid material, which includes the following raw material components in parts by mass:

Polylactic acid: 100 parts;

Organic nucleating agent: 0.1 to 2 parts;

Inorganic nucleating agent: 1-20 parts;

Wherein, the polylactic acid is a mixture of poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA) with a mass ratio of 10:0.1-2.

In the technical scheme of the present application, PDLA, organic nucleating agent and inorganic nucleating agent are used in PLLA to increase the crystallization nucleation density of polylactic acid materials, and provide a large number of heterogeneous nucleation points for PLLA crystallization, which can be used in Thermodynamically stable crystal nuclei are rapidly formed at higher temperatures, and the crystal nuclei grow rapidly, shortening the crystallization induction period of polylactic acid materials, accelerating the growth rate of polylactic acid spherulites, increasing the number of spherulites instantly and rapidly increasing the crystallization rate in a limited space , so that the size and size distribution of spherulites are significantly reduced, and the crystallinity of polylactic acid is greatly improved. The resulting polylactic acid material has good heat resistance and toughness.

In the technical solution of the present application, because the crystallization process of polylactic acid is mainly divided into nucleation and crystal growth processes, the two processes jointly determine the speed of crystallization. Generally speaking, the high-temperature chain segment has strong mobility, the crystal growth rate is fast, but nucleation is difficult; the low-temperature chain segment has poor mobility, the crystal growth rate is slow, but the nucleation is fast. In the prior art, polylactic acid materials will experience the thermal history of melting and cooling, and the melt will be cooled and formed in a short period of time. Therefore, nucleating agents can be added to make up for the difficult problem of chain segment nucleation in the high temperature range, and make full use of the heat of the melt itself Crystal growth is carried out, thereby increasing the crystallinity of the polylactic acid material, thereby improving the heat resistance and tensile strength of the polylactic acid material.

Among them, the polylactic acid raw material is a mixture of PLLA and PDLA with a mass ratio of 10:0.1~2. In the melt, the PDLA chain segments can be dispersed in the PLLA matrix and the chain segments can be arranged to obtain stereocomplex crystals. Compared with PLLA crystals , The melting temperature of the stereocomplex crystal is higher, so at the processing temperature of the polylactic acid material, the stereocomplex crystal exists in the solid phase, so it can be used as a crystal nucleus to increase the crystallization rate and crystallinity of the polylactic acid material. Compared with the use of nucleating agents, PDLA has better compatibility in the polylactic acid system, does not affect other properties of polylactic acid materials, and can reduce the addition of other nucleating agents, but it shortens the effect of nucleation induction period limited, and the cost of PDLA is high, so this application adds a certain amount of organic and inorganic nucleating agents to synergistically crystallize in the melt to increase the nucleation density of polylactic acid materials and further reduce the nucleation induction period.

PDLA, organic nucleating agent, and inorganic nucleating agent cooperate to crystallize through their different nucleation effects, and a large number of spherulites can be formed in a short period of time. Due to the limited space, the growth of spherulites is restricted, and the resulting spherulite size Smaller, so although the crystallinity and crystal density of the polylactic acid material are significantly improved, the toughness of the obtained polylactic acid material is also greatly improved due to the smaller size of the spherulites. Therefore, the polylactic acid material provided by this application has good heat resistance and toughness.

In the technical solution of the present application, the addition amount of the organic nucleating agent and the inorganic nucleating agent is also limited. Since the organic nucleating agent has poor dispersibility in the melt, excessive addition will lead to a decrease in crystallinity; On the one hand, the nucleating agent has the problem of dispersibility, and at the same time, excessive addition will also lead to an increase in the brittleness of the polylactic acid material. Therefore, this application controls the addition of PDLA, organic nucleating agent and inorganic nucleating agent to improve the crystallinity. The size of the spherulites is refined and the size distribution of the spherulites is reduced to obtain a polylactic acid material with good heat resistance and toughness.

As an example, the PLLA used in this application is high-viscosity polylactic acid pure resin, molecular optical purity L-lactic acid content > 99%, melt index (Flow, 190°C/2.16kg) = 3g/10min, tensile modulus ≥ 3500MPa , tensile strength ≥ 50MPa, Charpy notched impact strength ≤ 5kJ/m ² , residual monomer content ≤ 0.3%, water content ≤ 400ppm, heat distortion temperature (C-HDT B) in crystalline form = 100-110°C.

PDLA used in this application is low-viscosity poly-D-lactic acid resin, molecular optical purity D-lactic acid content > 99%, melt index (Flow, 190°C/2.16kg) > 50g/10min, tensile modulus ≥ 3500MPa, tensile Strength ≥ 50MPa, Charpy notched impact strength ≤ 5kJ/m ² , moisture content ≤ 400ppm.

In some embodiments of the present application, the organic nucleating agent includes sodium benzoate, hydroxyapatite, sodium lignosulfonate, zinc phenylphosphonate, aromatic sulfonate derivatives, rare earth β crystal nucleating agent, One or more of aramid-type β-nucleating agents, sebacic acid dibenzohydrazide and polyamide compounds; and/or

The inorganic nucleating agent includes one or more of modified talc powder, nano-modified montmorillonite, and nano-titanium dioxide.

Wherein, in the modified talc powder, the particle size D50=0.5～1.5 μm, D98≤6 μm, the silicon dioxide content≥60wt%, the magnesium oxide content is 30～35wt%,

Nano-modified montmorillonite is an organic montmorillonite modified by double long-chain alkyl ammonium, and the interlayer spacing is ≥3.5nm.

Nano-titanium dioxide is rutile-type titanium dioxide, with an average particle size of 30-60nm. .

In some of the above-mentioned embodiments, the above-mentioned organic nucleating agents commonly used in the field can increase the crystallization temperature of polylactic acid, and those skilled in the art can choose one or several of them according to actual needs.

Since the inorganic nucleating agent itself acts as a heterogeneous nucleation point, it has the best effect of shortening the nucleation induction period, but it will affect the transparency and gloss of the material, and will also affect the distribution of the crystal nucleus size. In addition, the inorganic nucleating agent Nucleating agents can make PLA materials brittle. Therefore, one or more of the above-mentioned modified talcum powder, nano-modified montmorillonite, and nano-silicon dioxide can be used as inorganic nucleating agents to reduce the above-mentioned effects.

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Polybutylene succinate (PBS): 1-60 parts.

In some of the above embodiments, PBS resin with high strength, high modulus and good heat resistance is added to the polylactic acid material to further improve the heat resistance and mechanical properties of the polylactic acid material. Generally speaking, the crystallization of polylactic acid and PBS in the melt will inhibit each other, the total crystallinity of the material will decrease, and the toughness of the material will increase accordingly. However, it is found through experiments in this application that the addition of PBS has an effect on the heat resistance of the material. The reason may be that although PBS has a certain influence on the total crystallinity, under the action of PDLA, organic nucleating agent and inorganic nucleating agent, the nucleation density of the material is still high, and the polycrystalline The crystallization of lactic acid and PBS will inhibit each other and inhibit the growth of spherulites, thereby refining the size of spherulites and reducing the distribution of spherulite sizes; at the same time, PBS has better heat resistance, so the polylactic acid obtained by adding PBS resin blended The heat resistance of the material is not greatly affected, but its toughness is further improved.

As an example, the melt index (Flow, 190°C/2.16kg) of the PBS resin used in the present application=4～7g/10min, heat distortion temperature (HDT B/Tff0.45)≥88°C, flexural modulus≥600MPa , tensile strength ≥ 43MPa, elongation at break ≥ 300%, Charpy notched impact strength ≥ 6KJ/m2, carboxyl content ≤ 20mol/t, moisture content ≤ 0.02%, ash content ≤ 0.1%, color value (L ≥ 75 , a≤5, b≤10).

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Polyhydroxyalkanoate (PHA): 1-50 parts;

Polyhydroxyalkanoates include poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and One or more of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB).

In some of the above embodiments, PHA is a kind of intracellular polyester synthesized by many bacteria, so it has good biocompatibility and biodegradability. In order to further improve the biodegradation rate of polylactic acid materials, therefore, polylactic acid Adding PHA material to the material can accelerate the biodegradation rate of the polylactic acid material and reduce the biodegradation condition of the polylactic acid material. At the same time, the heat resistance and mechanical properties of polylactic acid materials can be further improved by adjusting the type of PHA.

PHBV, PHBH and P34HB are commonly used polyhydroxyalkanoates in this field. In addition to good biodegradability, they also have good heat resistance and mechanical properties. Mixing can further improve the heat resistance and mechanical properties of polylactic acid materials.

As an example, the weight average molecular weight (Mw) of the PHBV used in this application=300,000, 3-hydroxyvaleric acid (3-HV) content=2%, melt index (Flow, 190 ℃/2.16kg)=5～ 10g/10min, tensile modulus ≥ 1800MPa, flexural modulus ≥ 2500MPa, heat distortion temperature ≥ 155°C, tensile strength ≥ 39MPa, elongation at break < 5%, Vicat softening point (A/50) = 166°C .

As an example, the weight average molecular weight (Mw)=400,000 of the PHBH used in the application=400,000, molecular weight distribution index (PDI)=1.83, 3-hydroxyhexanoic acid (3-HH) content is 11%, melt index (Flow, 165°C/5kg) = 5g/10min, tensile modulus ≥ 950MPa, flexural modulus ≥ 850MPa, tensile strength ≥ 26MPa, elongation at break ≥ 320%, Charpy notched impact strength ≥ 3kJ/m ² .

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Compatibility and toughening agent: 0.02 to 15 parts; Compatibility and toughening agents include vinyl acetate copolymer, vinyl acetate-ethylene copolymer, ethylene-n-butyl acrylate-glycidyl methacrylate terpolymer, ethylene -Methacrylic acid-glycidyl methacrylate, butyl acrylate-methyl methacrylate core-shell copolymer, methyl methacrylate-butadiene-styrene terpolymer, diisopropyl peroxide One or more of benzene.

In some of the above-mentioned embodiments, in order to improve the compatibility of the raw material components of polylactic acid and make the components in the melt more uniformly dispersed, so that each component can fully exert its modification effect, it can be added to the polylactic acid material Compatibility and toughening agent, polylactic acid can undergo interfacial reaction with the compatibilization and toughening agent, which can reduce the interfacial tension between incompatible components and improve the interfacial strength, and cooperate with other functional additives or blended resins to obtain heat resistance And polylactic acid materials with better mechanical properties. The above-mentioned types of compatibilizing and toughening agents are commonly used in the field, and those skilled in the art can add one or more of them according to actual needs.

In some embodiments of the present application, the following raw material components are also included in parts by mass:

Plasticizer: 0.5 to 4 parts; plasticizers include acetylated monoglyceride fatty acid esters, epoxidized soybean oil, acetyl tributyl citrate, tributyl citrate, dioctyl adipate, glycerin, Sorbitol, pentaerythritol, dipentaerythritol, macrogol-500, macrogol-1500, macrogol-2000, macrogol-3000, macrogol-4000, macrogol-6000 one or more of the following; and/or

Chain extender: 0.1-0.6 parts; the chain extender is styrene-methyl acrylate-glycidyl methacrylate terpolymer; and/or

Filler: 3 to 15 parts; the filler is light active nano-calcium carbonate; and/or

Lubricants: 0.1-0.8 parts; lubricants include one or more of ethylene bis stearic acid amide, pentaerythritol stearate, erucic acid amide, oleic acid amide, stearic acid, zinc stearate; and /or

Dispersant: 0.1-0.5 parts; the dispersant is one or more of ethylene acrylic acid copolymer, 26# food grade white mineral oil, low-density polyethylene wax, and oxidized low-density polyethylene wax.

In some of the above-mentioned embodiments, functional additives such as plasticizers, chain extenders, fillers, lubricants, and dispersants can also be added according to actual needs. Plasticizers can separate the chain segments of each polymer to weaken The intermolecular force improves the plasticity of polylactic acid materials; the chain extender can shield the water-absorbing groups at both ends of polylactic acid molecules and reduce its hygroscopicity; the filler uses light active nano-calcium carbonate, which can absorb impact energy and prevent polylactic acid The silver craze of the material expands to improve the notched impact strength of the material and the toughness of the material; the dispersant can disperse the solid particles that are difficult to dissolve in the melt, and at the same time prevent the solid particles from settling and agglomerating.

As an example, the average primary particle size of the light active nano-calcium carbonate used in this application is 60-70nm, the whiteness is ≥97%, the specific surface area is 23±4m ² /g, the water content is ≤0.3%, and the pH value is = 8.5～9.5, oil absorption value = 28±5ml/100g (DOP), crystal form is calcite crystal form, CaCO ₃ content ≥ 96%, MgO content ≤ 0.5%, SiO ₂ content ≤ 1.5%, (Fe ₂ O ₃ +MnO ₂ ) The content is ≤0.1%, the surface treatment agent is a fatty acid composite treatment agent, and the activation degree is ≥99%.

In a second aspect, the present application also provides a method for preparing a polylactic acid material, comprising the following steps:

The raw material components of the polylactic acid material according to any embodiment of the first aspect are mixed uniformly and then extruded to obtain the polylactic acid material.

In the technical solution of the present application, since the raw material components of the polylactic acid material in any embodiment of the first aspect have good compatibility, it is only necessary to simply blend and extrude each raw material component to have good heat resistance The material is tough and tough, and the preparation method is simple, which is suitable for industrial production.

In some embodiments of the present application, PDLA, PLLA, PBS, and PHA need to be dried before the raw material components are mixed.

In some of the above-mentioned embodiments, the above-mentioned materials can easily absorb moisture in the air during storage, resulting in an increase in the moisture content of the plastic. If it is not dried, it may cause apparent quality problems such as bubbles or streaks in the material, and even reduce the quality of the material. performance indicators.

In some embodiments of the present application, the following steps are specifically included:

Dry PDLA, PLLA, PBS, PHA;

Mix dry-processed PDLA, PLLA, PBS, PHA with inorganic nucleating agent, organic nucleating agent, filler, dispersant, lubricant, chain extender, compatibilizer and toughener, and plasticizer to uniformly extrude and granulate A polylactic acid material is obtained.

In some embodiments of the present application, extrusion granulation specifically includes:

Extrusion and granulation are carried out in a twin-screw extruder; among them, the processing temperature range of the twin-screw extruder is 105-195°C, and the heating sections of the twin-screw extruder gradually increase from 105°C to 195°C, and the speed of the twin-screw main engine is 100 ～350r/min, the residence time of the material in the twin-screw extruder is less than 5min, and the length-to-diameter ratio of the screw is 36～52.

In the third aspect, the present application also provides a polylactic acid product, which is obtained by processing the polylactic acid material according to any embodiment of the first aspect or the second aspect.

In the technical solution of the present application, since the polylactic acid material in any embodiment of the first aspect or the second aspect has good heat resistance and toughness, the polylactic acid material has good processability, and can obtain heat-resistant deformation. It is a polylactic acid product that is not easy to break, and at the same time, the product has good biodegradability and is green and environmentally friendly.

In the fourth aspect, the present application also provides a method for preparing polylactic acid products, comprising the following steps:

Use the polylactic acid material according to any embodiment of the first aspect or the second aspect to obtain a polylactic acid product through hot molding or cold molding in a blister machine.

In the technical solution of the present application, since the crystallization induction period of the polylactic acid material in any embodiment of the first aspect or the second aspect is short, different blister molding processes can be used to obtain polylactic acid products with good performance. The spherulite growth rate of lactic acid material is fast, which can shorten the blister molding cycle and achieve the purpose of reducing cost and improving efficiency.

In some embodiments of the present application, the polylactic acid material needs to be extruded through a sheet extruding machine to obtain a polylactic acid sheet before using a plastic absorbing machine to form by hot or cold molding.

In some of the above embodiments, the polylactic acid sheet is easier to process into products of different shapes than the polylactic acid material obtained by extrusion granulation.

In some embodiments of the present application, the processing temperature range of the parallel twin-screw extrusion sheet machine is 110°C to 190°C, and the heating sections of the sheet extrusion machine are gradually increased from 110°C to 190°C; the speed of the main engine is 100 to 350e/min , The residence time of the material in the extruder is less than 5min; the length-to-diameter ratio of the screw is 18-46.

In some embodiments of the present application, hot film blistering specifically includes:

Thermoforming Blister forming Blister machine is equipped with a mold temperature controller, through which the temperature of the blister molding mold is controlled at 90°C to 120°C, and the crystallization time of the polylactic acid sheet in the blister mold is 35s to 60s. Blister forming Blister machine processing temperature is 160 ℃ ~ 190 ℃.

In some embodiments of the present application, cold film blister specifically includes:

The temperature of the cold mold blister molding mold is controlled within the temperature range of 2°C to 10°C, the residence time of the polylactic acid sheet in the blister mold is 5s to 15s, and the products are taken out of the cold mold and put into the oven in batches for crystallization heat treatment. The crystallization heat treatment temperature is 90° C. to 120° C., the crystallization heat treatment time is 3 to 7 minutes, and the processing temperature of the cold mold blister molding machine is 160° C. to 190° C.

Hereinafter, the polylactic acid material of the present application and its preparation method and products are described in more detail through examples, but the present application is not limited to these examples in any way. The raw materials used in the examples are all commercially available unless otherwise specified.

The heat deflection temperature is tested according to GB/T 1634.1-2004 "Determination of Plastic Load Deformation Temperature";

Notched impact strength of Charpy beams is tested according to GB/T1043.1-2008 "Determination of Impact Properties of Plastic Charpy Beams"; GB/T1043.1-2008 Determination of Impact Properties of Plastic Charpy Beams

Elongation at break, tensile strength GB/T 1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets" were tested;

The degradation time of home composting (degradation rate ≥ 90%) is tested according to GB/T 40553-2021 "Technical Specifications for Plastics Suitable for Home Composting".

Example 1

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.6;

Sodium benzoate: 0.5 parts;

Modified talcum powder: 5 parts;

PBS: 10 copies;

PHA: 10 parts; PHA is a mixture of PHBV and PHBH with a mass ratio of 1:0.5;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.8 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.5 part;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material:

Pre-dry PLLA and PDLA at 80°C before use, the drying time is ≥4 hours, and the moisture content after drying is ≤0.04%; pre-dry PBS at 70°C before use, and the drying time is ≥4 Hours, moisture content after drying ≤0.02%; pre-dry PHBV at 80°C before use, drying time ≥4 hours, moisture content after drying ≤0.025%; pre-dry PHBV at 55°C before use Pre-drying, drying time ≥ 6 hours, moisture content ≤ 0.025% after drying;

Weigh the pre-dried PLLA, PDLA, PBS, PHBV, and PHBH according to the above mass parts, put them into a high-speed mixer after weighing, and start stirring at a low speed. While stirring, add the weighed sodium benzoate and modified talcum powder in sequence , vinyl acetate copolymer, acetylated monoglyceride fatty acid ester, styrene-methyl acrylate-glycidyl methacrylate terpolymer, light activated nano-calcium carbonate, ethylene bisstearamide, ethylene Acrylic acid copolymer, after the addition is completed, first stir at a low speed for 15 minutes, then stir at a high speed for 8 minutes, put the evenly mixed material into a twin-screw extruder to extrude and granulate, and dry at 80°C for 6 hours after granulation. The rate must be controlled below 0.02% to obtain polylactic acid materials; among them, the processing temperature range of the twin-screw extruder is 105-195°C, the heating sections of the extruder gradually increase from 105°C to 195°C, and the speed of the main engine of the twin-screw extruder 270r/min, the residence time of the material in the extruder is less than 5min, and the length-to-diameter ratio of the screw is 40.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Example 2

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.1;

Sodium benzoate: 0.2 parts;

Modified talcum powder: 5 parts;

Vinyl acetate copolymer: 0.1 part;

Acetylated mono-diglyceride fatty acid ester: 0.8 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.1 part;

Light active nano calcium carbonate: 3 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material:

Pre-dry PLLA and PDLA at 80°C before use, the drying time is ≥4 hours, and the moisture content after drying is ≤0.04%;

Weigh the pre-dried PLLA and PDLA according to the above mass parts, put them into a high-speed mixer after weighing, and start stirring at a low speed. While stirring, add the weighed sodium benzoate, modified talcum powder, and vinyl acetate copolymer in sequence , Acetylated mono-diglyceride fatty acid ester, styrene-methyl acrylate-glycidyl methacrylate terpolymer, light active nano-calcium carbonate, ethylene bis-stearic acid amide, ethylene acrylic acid copolymer, added to complete Then stir at low speed for 15 minutes, then stir at high speed for 10 minutes, put the mixed material into twin-screw extruder to extrude and granulate, and dry at 80°C for 6 hours after granulation. After drying, the moisture content must be controlled at 0.02%. The polylactic acid material is obtained as follows; wherein, the processing temperature range of the twin-screw extruder is 105-195°C, each heating section of the extruder is gradually increased from 105°C to 195°C, the main engine speed of the twin-screw extruder is 240r/min, and the material is The residence time in the extruder is less than 5min, and the aspect ratio of the screw is 48.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Example 3

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.3;

Sodium benzoate: 0.5 parts;

Modified talcum powder: 5 parts;

PHA: 20 parts; PHA is a mixture of PHBV and PHBH with a mass ratio of 1:0.1;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.5 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.3 parts;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material:

Pre-dry PLLA and PDLA at 80°C before use, the drying time is ≥4 hours, and the moisture content after drying is ≤0.04%; pre-dry PHBV at 80°C before use, and the drying time is ≥4 Hours, moisture content after drying ≤0.025%; pre-dry PHBH at 55°C before use, drying time ≥6 hours, moisture content after drying ≤0.025%;

Weigh the pre-dried PLLA, PDLA, PHBV, and PHBH according to the above mass parts, put them into a high-speed mixer after weighing, and start stirring at a low speed. While stirring, add the weighed sodium benzoate, modified talcum powder, and acetic acid in sequence Vinyl ester copolymer, acetylated monoglyceride fatty acid ester, styrene-methyl acrylate-glycidyl methacrylate terpolymer, light active nano calcium carbonate, ethylene bisstearic acid amide, ethylene acrylic acid copolymer After the addition is complete, first stir at low speed for 15 minutes, and then stir at high speed for 6 minutes. Put the uniformly mixed material into a twin-screw extruder to extrude and granulate. After granulation, dry it at 80°C for 6 hours. After drying, the moisture content must be Control it below 0.02% to obtain polylactic acid materials; among them, the processing temperature range of the twin-screw extruder is 105-195°C, the heating sections of the extruder gradually increase from 105°C to 195°C, and the speed of the main engine of the twin-screw extruder is 300r/ min, the residence time of the material in the extruder is less than 5min, and the aspect ratio of the screw is 40.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Example 4

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.3;

Sodium benzoate: 0.5 parts;

Modified talcum powder: 5 parts;

PBS: 20 copies;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.5 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.3 parts;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 parts;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material:

Pre-dry PLLA and PDLA at 80°C before use, the drying time is ≥4 hours, and the moisture content after drying is ≤0.04%; pre-dry PBS at 70°C before use, and the drying time is ≥4 Hours, moisture content after drying ≤ 0.02%;

Weigh the pre-dried PLLA, PDLA, and PBS according to the above mass parts, put them into a high-speed mixer after weighing, and start stirring at a low speed. While stirring, add the weighed sodium benzoate, modified talcum powder, and vinyl acetate in sequence Copolymer, acetylated mono-diglyceride fatty acid ester, styrene-methyl acrylate-glycidyl methacrylate terpolymer, light active nano-calcium carbonate, ethylene bis-stearamide, ethylene acrylic acid copolymer, After the addition is completed, first stir at low speed for 15 minutes, and then stir at high speed for 10 minutes. Put the evenly mixed material into a twin-screw extruder for extrusion and granulation. After granulation, dry it at 80°C for 6 hours. After drying, the moisture content must be controlled at Below 0.02%, the polylactic acid material is obtained; wherein, the processing temperature range of the twin-screw extruder is 105-195°C, the heating sections of the extruder are gradually increased from 105°C to 195°C, and the main engine speed of the twin-screw extruder is 240r/min. The residence time of the material in the extruder is less than 5min, and the aspect ratio of the screw is 48.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Comparative example 1

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is pure PLLA;

Sodium benzoate: 0.5 parts;

Modified talcum powder: 5 parts;

PBS: 10 copies;

PHA: 10 parts; PHA is a mixture of PHBV and PHBH with a mass ratio of 1:0.5;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.8 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.5 parts;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material: except that PDLA is not added, others are the same as in Example 1.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Comparative example 2

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.6;

Modified talcum powder: 5 parts;

PBS: 10 copies;

PHA: 10 parts; PHA is a mixture of PHBV and PHBH with a mass ratio of 1:0.5;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.8 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.5 part;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material: same as Example 1 except that sodium benzoate is not added.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Comparative example 3

Preparation method of polylactic acid material:

The raw material components of polylactic acid materials, by mass parts, include:

Polylactic acid: 100 parts; polylactic acid is a mixture of PLLA and PDLA with a mass ratio of 10:0.6;

Sodium benzoate: 0.5 parts;

PBS: 10 copies;

PHA: 10 parts; PHA is a mixture of PHBV and PHBH with a mass ratio of 1:0.5;

Vinyl acetate copolymer: 2 parts;

Acetylated mono-diglyceride fatty acid ester: 0.8 parts;

Styrene-methyl acrylate-glycidyl methacrylate terpolymer: 0.5 part;

Light active nano calcium carbonate: 5 parts;

Ethylene bis stearic acid amide: 0.6 part;

Ethylene acrylic acid copolymer: 0.3 parts.

Preparation of polylactic acid material: same as Example 1 except that no modified talcum powder is added.

The obtained polylactic acid material is processed into a sample to be tested, and it is tested for thermal deformation temperature, Charpy notched impact strength, elongation at break, tensile strength, and home compost degradation time (degradation rate ≥ 90%). The results are shown in Table 1.

Table 1

Note: "/" indicates that it cannot be degraded normally in home compost

According to Table 1, by comparing the results of each embodiment and comparative example, it can be seen that the polylactic acid material prepared in Example 1 has higher heat distortion temperature, Charpy notched impact strength, elongation at break and tensile strength, It shows that by using PDLA, inorganic nucleating agent and organic nucleating agent, the polylactic acid material has good heat resistance, toughness and processability through the synergistic effect. In addition, by blending PBS and PHA resin, its heat resistance is further improved Good biodegradability and toughness of PBS and PHA can make the obtained polylactic acid material have a higher degradation rate.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit it; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present application. scope.

Claims (10)

1. A polylactic acid material, characterized in that, in parts by mass, comprising the following raw material components: Polylactic acid: 100 parts; Organic nucleating agent: 0.1 to 2 parts; Inorganic nucleating agent: 1-20 parts; Wherein, the polylactic acid is a mixture of poly-L-lactic acid and poly-D-lactic acid with a mass ratio of 10:0.1-2. 2. The polylactic acid material according to claim 1, wherein said organic nucleating agent comprises sodium benzoate, hydroxyapatite, sodium lignosulfonate, zinc phenylphosphonate, aromatic sulfonate derivatives One or more of rare earth β-crystal nucleating agents, aramid-type β-nucleating agents, sebacic acid dibenzohydrazide and polyamide compounds; and/or The inorganic nucleating agent includes one or more of modified talcum powder, nano-modified montmorillonite, and nano-titanium dioxide, Wherein, in the modified talc powder, the particle size D50=0.5-1.5 μm, D98≤6 μm, the content of silicon dioxide ≥60 wt%, the content of magnesium oxide is 30-35 wt%, The nano-modified montmorillonite is an organic montmorillonite modified by double long-chain alkyl ammonium, and the interlayer spacing is ≥3.5nm, The nano-titanium dioxide is rutile-type titanium dioxide with an average particle diameter of 30-60nm. 3. polylactic acid material according to claim 1, is characterized in that, by mass parts, also comprises following raw material component: Polybutylene succinate: 1 to 60 parts. 4. The polylactic acid material according to claim 1 or 3, characterized in that, in parts by mass, it also includes the following raw material components: Polyhydroxyalkanoate: 1-50 parts; The polyhydroxyalkanoate includes poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxycaproate) and poly(3-hydroxybutyrate-co-3-hydroxycaproate) One or more of hydroxybutyrate-co-4-hydroxybutyrate). 5. polylactic acid material according to claim 1, is characterized in that, by mass parts, also comprises following raw material component: Compatibility and toughening agent: 0.02 to 15 parts; said compatibilization and toughening agent includes vinyl acetate copolymer, vinyl acetate-ethylene copolymer, ethylene-n-butyl acrylate-glycidyl methacrylate terpolymer , ethylene-methacrylic acid-glycidyl methacrylate, butyl acrylate-methyl methacrylate core-shell structure copolymer, methyl methacrylate-butadiene-styrene terpolymer, diperoxide One or more of cumene. 6. polylactic acid material according to claim 1, is characterized in that, by mass parts, also comprises following raw material component: Plasticizer: 0.5 to 4 parts; the plasticizer includes acetylated monoglyceride fatty acid ester, epoxidized soybean oil, acetyl tributyl citrate, tributyl citrate, dioctyl adipate, Glycerin, Sorbitol, Pentaerythritol, Dipentaerythritol, Macrogol-500, Macrogol-1500, Macrogol-2000, Macrogol-3000, Macrogol-4000, Polyethylene Glycol - one or more of 6000; and/or Chain extender: 0.1 to 0.6 parts; the chain extender is styrene-methyl acrylate-glycidyl methacrylate terpolymer; and/or Filler: 3 to 15 parts; the filler is light active nano-calcium carbonate; and/or Lubricant: 0.1-0.8 parts; the lubricant includes one or more of ethylene bis stearic acid amide, pentaerythritol stearate, erucic acid amide, oleic acid amide, stearic acid, and zinc stearate ;and / or Dispersant: 0.1-0.5 parts; the dispersant is one or more of ethylene acrylic acid copolymer, 26# food-grade white mineral oil, low-density polyethylene wax, and oxidized low-density polyethylene wax. 7. A preparation method of polylactic acid material, is characterized in that, comprises the following steps: The polylactic acid material is obtained by extruding after uniformly mixing the raw material components of the polylactic acid material according to any one of claims 1-6. 8. preparation method according to claim 7, is characterized in that, specifically comprises the following steps: Drying the poly-D-lactic acid, poly-L-lactic acid, polybutylene succinate, and polyhydroxyalkanoate; Drying poly-D-lactic acid, poly-L-lactic acid, polybutylene succinate, polyhydroxyalkanoate and the inorganic nucleating agent, organic nucleating agent, filler, dispersant, lubricant, chain extender The polylactic acid material is obtained by uniformly mixing and extruding granulating agent, compatibilizing and toughening agent and plasticizer. 9. preparation method according to claim 8, is characterized in that, described extrusion granulation specifically comprises: Extrusion and granulation are carried out in a twin-screw extruder; wherein, the processing temperature range of the twin-screw extruder is 105-195°C, and each heating section of the twin-screw extruder gradually increases from 105°C to 195°C, and the twin-screw extruder The speed is 100-350r/min, the residence time of the material in the twin-screw extruder is less than 5min, and the length-to-diameter ratio of the screw is 36-52. 10. A polylactic acid product, characterized in that the polylactic acid product obtained by processing the polylactic acid material according to any one of claims 1-9.