CN212528977U

CN212528977U - Biodegradable paper-plastic composite structure

Info

Publication number: CN212528977U
Application number: CN201922458364.5U
Authority: CN
Inventors: 苏日挺; 孙利辉; 苏凯; 梁银春; 于星; 宋晓梅
Original assignee: Kunming Cellulose Fibers Co ltd; Zhuhai Cellulose Fibers Co ltd; Nantong Cellulose Fibers Co Ltd
Current assignee: Kunming Cellulose Fibers Co ltd; Zhuhai Cellulose Fibers Co ltd; Nantong Cellulose Fibers Co Ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2021-02-12
Anticipated expiration: 2029-12-30

Abstract

A biodegradable paper-plastic composite structure comprising: at least one cellulose acetate or derivative film thereof; a paper substrate; the cellulose acetate or the derivative film thereof is combined with a paper substrate to form a paper-plastic composite structure. The cellulosic material included in the formulation comprises cellulose acetate or a derivative thereof having a degree of substitution of 1.5 to 2.8. Also comprises a plasticizer capable of reducing the softening temperature of the cellulose. The base paper material is paper produced by physically processing cellulose pulp, such as kraft paper, parchment paper, and the like. The preparation method of the biodegradable paper-plastic composite structure comprises the steps of compounding the cellulose acetate film by a heating and pressurizing method, or compounding by a solution coating method, namely coating the cellulose acetate solution on the surface of paper, and evaporating the solvent to prepare the paper composite material containing cellulose acetate. The utility model discloses the goods can be used in food field or packing field, can degrade in order to eliminate or reduce the environmental pollution problem that packaging material brought naturally.

Description

Biodegradable paper-plastic composite structure

Technical Field

The utility model belongs to the technical field of the cellulose acetate is used, a preparation of cellulose acetate composite film that can be applied to the packing is related to.

Technical Field

Plastic films are most widely used in the packaging field. The plastic film can be used for food packaging, electric appliance product packaging, daily necessity packaging, clothing packaging and the like.

The film for packaging is usually a paper-plastic composite film. The paper-plastic composite package is a composite material compounded by using paper as a base material and thermoplastic plastics and the like. The paper material has certain thickness, shape stability and higher folding endurance. As the thermoplastic, polyethylene, polypropylene, polyvinylidene chloride, polyethylene terephthalate, etc. are generally used. Two kinds of compounding technology are available, one type of paper-plastic dry compounding, which is to coat a plastic film with a compound emulsion type acrylate adhesive and then bond the plastic film and paper together under the action of a hot press roll; the other is paper-plastic water-based cold-pasting compounding, which is to coat the polymer film with water-based glue and to laminate with paper to form a compound die. Can be applied to the fields of food, medicine, daily chemicals, electronic components, clothing packaging and the like.

Most of the traditional packaging materials are petroleum-based materials. Many packaging materials, such as films, are difficult to degrade in the environment after use, are broken into plastic particles, are scattered in soil and water, and put pressure on environmental protection. In 2019, 3, 27 days, the european parliament concluded that disposable plastic products were banned through one-time plastic product ban, and the one-time plastic products were banned completely since 2021 to control environmental pollution caused by plastic wastes.

CN110451066A provides an acrylic ester-based paper-plastic composite packaging bag and a manufacturing method thereof, and the preparation material of the environment-friendly paper-plastic composite packaging bag comprises a paper layer and a plastic layer. And compounding the prepared plastic layer and the paper layer to form a composite paper-plastic layer, and processing the composite paper-plastic layer into the environment-friendly paper-plastic composite packaging bag. CN110451067A provides a waterproof paper-plastic composite packaging bag and a manufacturing method thereof, wherein the preparation material of the waterproof paper-plastic composite packaging bag comprises a paper layer and a fluorocarbon resin-based plastic layer. The prepared plastic layer and the paper layer are compounded to form a composite paper-plastic layer, and the composite paper-plastic layer is processed into a waterproof paper-plastic composite packaging bag, so that the processing technology is simple.

The degradable material may be added into polymer material, and inorganic salt, such as calcium carbonate, or natural polymer, such as wood powder, starch, etc. may be added. Although effective to some extent, this approach leaves the resin substrate as a petroleum-based material that is difficult to degrade, and the small particulate non-degradable plastic remaining after degradation can be even more environmentally hazardous.

CN110330718A discloses a fully degradable polyethylene plastic film and a preparation method thereof, the components mainly comprise polyethylene, ecological degradable plastic master batch, starch, nano zinc oxide, ascorbic acid, polyvinyl alcohol and cellulose acetate. CN110467765A A polyethylene film with antibacterial and degradable functions and a preparation method thereof. The plastic product produced by the method can be quickly disintegrated in the environment, but the resin-based material of the plastic product can be quickly flowed into the environment in the form of particles, and the problem of white pollution is difficult to be solved essentially.

Essentially solving the need to adopt fully biodegradable materials, such as PLA, PHA and other materials. CN110511442A discloses a degradable ring based polylactic acid (PLA) plastic film formulation, which contains 15-20% polylactic acid. CN110283343A discloses a high-strength high-ductility polylactic acid film material and a preparation method thereof, comprising the following steps: (1) drying the raw materials; (2) extruding to prepare a polylactic acid casting film; (3) and stretching to prepare the polylactic acid stretched film. CN109593333A discloses a PLA/PHBV composite material with high mechanical strength and biodegradability.

The other option is that cellulose is used as a raw material and can be applied to environment-friendly degradable materials after acylation. Juergen Puls et al, in the Degradation of Cellulose Acetate Materials, summarize the Degradation properties of Cellulose Acetate.

Films can be prepared using cellulose esters. CN110003533A discloses a cellulose acetate composite material and application thereof. The composite material realizes the direct melt processing of the cellulose acetate base material under the condition of no external micromolecule plasticizer by blending the cellulose derivative with low glass transition temperature and the cellulose acetate base, and can be prepared into any one of powder, microspheres, films and blocky solids. The utility model adopts cellulose derivative to plasticize.

CN103772752B A fruit preservative film and a preparation method thereof: dissolving cellulose acetate and cellulose acetate propionate in water, adding polyethylene glycol, glutaraldehyde, silicon dioxide and antibacterial zeolite, extruding by adopting a double screw, plasticating and blowing a film to prepare the single fruit preservative film. This patent does not disclose a composite film of cellulose film and paper.

The cellulose acetate film may be prepared through solvent process, dissolving cellulose acetate in acetone, ethyl acetate, dimethyl acetamide, etc, adding plasticizer and assistant and stirring to obtain transparent homogeneous casting liquid. And standing the casting solution for defoaming. And casting or blade-coating the casting solution on a glass substrate with a certain thickness, and then drying, separating and rolling to obtain the cellulose acetate membrane.

CN106589439A discloses a preparation method for preparing a cellulose acetate and silicon dioxide hybrid membrane by using a solvent method. The obtained cellulose acetate and silicon dioxide hybrid membrane has super-hydrophobicity and can be used as a packaging material. In this method, skin-damaging ingredients are used, and N, N-dimethylformamide and glutaraldehyde are irritant to the skin mucosa.

SUMMERY OF THE UTILITY MODEL

The technical demand to can pack the film, the utility model aims to provide a material that can biodegradable makes environmental protection paper and moulds composite construction, can be applied to packaging material, can natural degradation in order to eliminate or reduce rather than relevant environmental pollution problem.

In order to achieve the above purpose, the utility model discloses a solution is:

a biodegradable paper-plastic composite structure comprising at least one film of cellulose acetate or a derivative thereof; a paper substrate;

the cellulose acetate or the derivative film thereof is combined with a paper substrate to form a paper-plastic composite structure.

The utility model adopts cellulose as raw material to prepare biodegradable degradable environment-friendly plastic which can be processed by acylation. Cellulose has abundant sources in nature, can be used as a raw material after purification, and can efficiently prepare a biodegradable cellulose-based environment-friendly material without causing environmental pollution. The cellulose can be derived from wood pulp, cotton pulp, and herbal fiber such as hemp, straw, etc.

Cellulose acetate is made from natural cellulose through acetylation reaction, and can be degraded in environment. However, the main chain of the cellulose acetate is composed of 1, 4-beta-D-glucopyranosyl, which is a rigid chain, and the rest hydroxyl groups after cellulose acetylation exist in intramolecular and intermolecular hydrogen bond structures, so that the cellulose acetate cannot be directly melt-processed. Must be plasticized with a plasticizer for further processing.

The main chain of the cellulose acetate is composed of 1, 4-beta-D-glucopyranose, 3 hydroxyl groups at2, 3 and 6 positions of each glucose ring can be acylated, generally can be substituted by acetyl, propionyl or butyryl, and can be singly or in a plurality of ways, and the content of each substituent can be controlled according to needs and can be between 0.1 and 3. The cellulose acetate widely used for producing the tobacco filtering material has the substitution degree of 2.4-2.7, wherein the cellulose acetate contains acetyl substitution groups and unreacted carboxyl; the following formula:

wherein

Cellulose acetate production requires cellulose from wood or cotton to be more than 90% pure. The viscosity of the cellulose is 5-10 dL/g. The cellulose viscosity is the intrinsic viscosity in the cuprammonium solution, and the absolute cellulose is dissolved in 50% cuprammonium water to prepare a solution with the concentration of 0.25%, and the intrinsic viscosity is measured by an Ubbelohde viscometer at25 ℃.

The cellulose acylating agent can be selected from acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, or a mixture of one or more of the above. The general process is that the cellulose is pretreated by activation, and then catalyst, generally sulfuric acid and corresponding acid anhydride are added, and the finished product is obtained by acylation, hydrolysis, precipitation, washing and drying.

If acetic anhydride is used for acetylation, the finished product is cellulose acetate, and the degree of substitution of acetyl (X + Y + Z) is in the range of 1.5-2.8, preferably 1.8-2.7, more preferably 1.9-2.6. The cellulose acetate has an intrinsic viscosity of 1.2 to 1.8dL/g, preferably 1.25 to 1.75dL/g, more preferably 1.35 to 1.7 dL/g. The molecular weight is 10000-; preferably, the molecular weight is 20000-; more preferably, its molecular weight is 25000-.

Or mixing acetic anhydride and propionic anhydride for acylation to obtain ethylene propylene Cellulose (CAP), with acetyl degree of substitution of 0.1-0.5 and propionyl degree of substitution of 1-2.5. The number average molecular weight ranges from 15000-.

Or mixing acetic anhydride and butyric anhydride for acylation to obtain ethylene propylene Cellulose (CAB), wherein the substitution degree of acetyl is 0.1-1.5, and the substitution degree of butyryl is 1-2.5. The number average molecular weight ranges between 15000 and 90000 Dalton.

The cellulose acetate and derivatives described above may be used to make films. Alternatively, the cellulose ester includes cellulose acetate, and cellulose acetate propionate, cellulose acetate butyrate having mixed groups.

The acylated cellulose can destroy hydrogen bonds or crystallinity of the cellulose to a certain extent, so that the cellulose material can be dissolved in a common solvent or can be subjected to glass transition, the softening temperature and the melting point are reduced, and the processing performance of the cellulose material is improved. The hydroxyl groups of the cellulose are grafted with hydrocarbon and carbonyl functional groups, so that the cellulose material has injection molding processability, such as CAB and CAP.

The cellulose derivative may also be a methyl cellulose ether, an ethyl cellulose ether, a carboxymethyl cellulose, a carboxyethyl cellulose, a hydroxypropyl cellulose and a hydroxypropyl methyl cellulose. The refined cotton is treated by alkali and etherified by chloromethane, ethylene oxide, propylene oxide or sodium monochloroacetate as etherifying agent.

If the substituent is mainly acetyl, the material can partially have the thermal processing performance, but cannot meet the requirement of thermal processing of industrial plastic products. Therefore, the plasticizer is required to be added to improve the plasticizing processing performance. Plasticizers are additives for polymer materials, which are widely used in industrial production, and are also called plasticizers. Any substance added to a polymeric material that increases the plasticity of the polymer is called a plasticizer. The plasticizer mainly has the effects of weakening the secondary valence bonds among resin molecules, increasing the mobility of resin molecular chains, reducing the crystallinity of the resin molecules, increasing the plasticity of the resin molecules, enhancing the flexibility of the resin molecules and improving the processability. But also can reduce the production cost and improve the production benefit. The plasticizer is generally added at a concentration that is compatible with the polymeric material and critical for phase separation.

Phthalates, a large class of lipid soluble compounds, are commonly used to modify thermoplastic polymers such as PVC. Such materials may also be used as plasticizers for cellulose acetate materials. Common are dimethyl phthalate (DMP), diethyl phthalate (DEP), di-2-ethylhexyl phthalate (DEHP), dibutyl phthalate (DBP) and diethyl phthalate (di-ethyl phthalate, DEP), dioctyl phthalate (DOP), Butyl Benzyl Phthalate (BBP), dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisooctyl phthalate, diisobutyl phthalate, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dicyclohexyl phthalate, and the like.

When the plasticizer of the cellulose acetate is diethyl phthalate (DEP), the mass fraction in the mixed material is 1% -45%, preferably 10% -40%, most preferably 25% -35%.

The utility model discloses in still including plasticizing agent, especially environmental protection class plasticizing agent, indicate not to cause harmful effects to the environment or can satisfy with food contact material requirement organic compound or oligomer. The optional range of environmentally friendly plasticizers includes one or more combinations of glycerides, citrates, acetylcitrites, ethylene glycol oligomers, propylene glycol oligomers, ethylene glycol propylene glycol copolymers, epoxidized vegetable oil esters, and other fatty acid ester plasticizers.

The environment-friendly plasticizer can also be epoxidized soybean oil, epoxidized butyl stearate, epoxidized butyl furoate, epoxidized butyl soybean oleate, epoxidized butyl cottonseed oleate, epoxidized butyl rapeseed oleate, epoxidized butyl tallate, epoxidized butyl xanthate and the like.

Environmentally friendly plasticizers may also be 2,2, 4-trimethyl-1, 3-pentanediol diisobutyrate, 2, 2-dimethyl-1, 3-propanediol, pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], sorbitan monolaurate, glycerol monostearate, glycerol mono-and dilaurate, trilaurate, di (2-ethylhexyl) adipate, diisononyl adipate, dodecanoate of a polymer of adipic acid with 1, 2-propanediol.

The environment-friendly plasticizer can also be isosorbide dicaprylate and bio-based polycaprolactone. The isosorbide dicaprylate is synthesized from natural isosorbide, is a nonionic surfactant, is applied to the field of cosmetics, and can also be used as a plasticizer. The bio-based polycaprolactone is a biodegradable material, and can be prepared by cyclization and ring-opening polymerization of hexanediol synthesized by hydrogenation of 5-hydroxymethylfurfural.

The above plasticizers may be used alone or in combination of two or more.

Several general classes of environmentally friendly plasticizers and their range of use for cellulose acetate plasticizers are described in detail below, respectively.

The environment-friendly plasticizer can be a glyceride plasticizer having the following molecular structure:

wherein,

alternatively, the above-mentioned glycerides refer to different carboxylic acid esters including monoglycerides, diglycerides, triglycerides, and the carboxylic acids include fatty acids having 2 to 18 carbon atoms, and the like.

When the plasticizer is glycerol triacetate, the glycerol triacetate is added to the blend material in an amount of 1% to 45%, preferably 10% to 45%, more preferably 25% to 40%.

The environment-friendly plasticizer may also be:

R₁O(CH2CH2O)_nR₂

wherein,

or is

Wherein,

R₇，R₈,R₉＝CH₃，C₂H₅,C₃H₇,C₅H₁₂,C₇H₁₅。

alternatively, the above citric acid esters include triethyl citrate, tripropyl citrate, tributyl citrate, and the like.

Alternatively, the above acetyl citrate esters include acetyl triethyl citrate, acetyl tripropyl citrate, acetyl tributyl citrate, and the like.

The citric acid ester plasticizer and the triacetyl glycerine plasticizer can be mixed for use, and the addition of the citric acid ester plasticizer can adjust the hydrophobicity of the material and reduce the migration of the plasticizer with strong hydrophilicity. If the glycerol triacetate and the tributyl citrate are mixed, the proportion of the tributyl citrate in the mixed plasticizer is in the range of 0.1% -60%, and preferably in the range of 20% to 45%. The method for determining the mixing ratio of the glycerol triacetate and the tributyl citrate comprises the following steps: (1) mixing glycerol triacetate and tributyl citrate according to a certain proportion; (2) dissolving cellulose acetate in acetone and then mixing with a mixed plasticizer; (3) the mixed solution was placed on a petri dish and air-dried naturally, and then observed for transparency. The transparent representation may be compatible. Turbidity indicates incomplete mutual solubility. The critical concentration of tributyl citrate is defined as the upper limit. The amount of the mixed plasticizer added to the cellulose acetate is 1% to 45%, preferably 10% to 45%, more preferably 25% to 40%.

If an acetylcitrate plasticizer and a triacetin plasticizer are used in combination, they may be triacetin and acetyltributyl citrate. The proportion of tributyl acetylcitrate in the mixed plasticizer is in the range of 0.1% -55%, preferably between 20% and 50%. The method for determining the mixing ratio of the glycerol triacetate to the acetyl tributyl citrate comprises the following steps: (1) mixing glycerol triacetate and acetyl tributyl citrate according to a certain proportion; (2) dissolving cellulose acetate in acetone and then mixing with a mixed plasticizer; (3) the mixed solution was placed on a petri dish and air-dried naturally, and then observed for transparency. Transparent representations may be mixed. Turbidity indicates incomplete mutual solubility. The critical concentration of acetyl tributyl citrate is defined as the upper limit. The amount of the mixed plasticizer added to the cellulose acetate is 1% to 45%, preferably 10% to 45%, more preferably 25% to 40%.

The plasticizer may also be one or more combinations of ethylene glycol oligomers, propylene glycol oligomers, or ethylene glycol propylene glycol copolymers, by which is meant ethylene glycol oligomers, propylene glycol oligomers, or ethylene glycol propylene glycol copolymers having a molecular weight between 150 and 1500g/mol, such as PEG 300, PEG 400, PEG 600; PEG 800 and PEG 1000. The end group of the ethylene glycol oligomer and the propylene glycol oligomer is hydroxyl. The numbers in the names represent the number average molecular weight of PEG in g/mol. The method for determining the mixing ratio of PEG and cellulose acetate comprises the following steps: PEG and cellulose acetate are mixed in acetone according to a certain proportion to form a transparent solution. The mixed solution was then placed in a petri dish and air-dried, and then heated to 80 ℃ to remove the solvent, and then the transparency of the film was observed. Transparent means compatible for blending. Turbidity indicates incomplete mutual solubility. The PEG plasticizer is chosen to ensure that the plasticizer is fully compatible with the cellulose acetate. Experiments show that when the molecular weight of PEG is equal to or less than 1000, the PEG is still miscible when the addition amount of PEG is 50%. When the PEG molecular weight is 1500g/mol, the compatibility content is 20%. According to the above rule, the PEG plasticizer molecular weight is preferably 200-1500g/mol, more preferably 250 to 800 g/mol. The plasticizer may be added in an amount of 1% to 45%, preferably 10% to 40%, more preferably 20% to 35%.

Alternatively, the terminal hydroxyl groups of the ethylene glycol oligomer, propylene glycol oligomer or ethylene glycol propylene glycol copolymer are substituted with alkyl or carboxylic acid groups, including triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, triethylene glycol diacetate; the amount of one or more plasticizers added is 1% to 45%, preferably 10% to 40%, more preferably 20% to 35%.

The epoxy vegetable oil ester comprises one or more of epoxy soybean oil, epoxy butyl stearate, epoxy butyl furoate, epoxy butyl soybean oleate, epoxy butyl cottonseed oleate, epoxy butyl rapeseed oleate, epoxy butyl tallate and epoxy butyl xanthate.

The fatty acid ester plasticizer comprises one or more of 2,2, 4-trimethyl-1, 3-pentanediol diisobutyrate, 2, 2-dimethyl-1, 3-propylene glycol, pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], sorbitan monolaurate, glycerol monostearate, glycerol mono-laurate, dilaurate, di (2-ethylhexyl) adipate, diisononyl adipate, dodecanoate of a polymer of adipic acid and 1, 2-propylene glycol, isosorbide dicaprylate or bio-based polycaprolactone. The isosorbide dicaprylate is synthesized from natural isosorbide, is a nonionic surfactant, is applied to the field of cosmetics, and can also be used as a plasticizer. The bio-based polycaprolactone is a biodegradable material, and can be prepared by cyclization and ring-opening polymerization of hexanediol synthesized by hydrogenation of 5-hydroxymethylfurfural.

Optionally, the formulation of the above-mentioned mixed material may further comprise inactive inorganic particles, and solid additive particles for adjusting whiteness or color or improving other properties, including but not limited to titanium dioxide, alumina, zirconia, glass beads, silica, silicate spheres, kaolin particles, sucrose powder, dextrin, lactose, sugar powder, glucose, mannitol, starch, methyl cellulose, ethyl cellulose, microcrystalline cellulose, polylactic acid, polyhydroxybutyrate, poly epsilon-caprolactone, polyglycolic acid, polyhydroxyalkanoate, crushed grains, and one or more of aluminum, iron, copper, and calcium sulfate. By unreactive inorganic inactive is meant that the particles do not chemically react with the cellulose acetate or reaction products thereof between room temperature and 100 ℃.

The particle shape includes spherical, spheroidal, pie, flake, ribbon, needle, polygonal, faceted, or random. The particles are nano-scale particles, the particle size range is 10-400nm, and the mass fraction of the particles in the mixed material is 0-10%.

When the added particles are TiO₂When used, the concentration is 0.05% to 5%, preferably 0.1% to 1%, more preferably 0.2% to 0.4%.

Further, an antioxidant, a heat stabilizer and an ultraviolet light stabilizer may be added as required. The antioxidant is widely used in high molecular materials and used for preventing the strength and toughness of polymer materials from losing due to oxidative degradation, and comprises pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), n-octadecyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1076), tris (2, 4-di-tert-butylphenyl) phosphite (antioxidant 168), 4,4' -thiobis (6-tert-butyl-3-methylphenol) (antioxidant 300), N ' -bis- (3- (35-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine (antioxidant 1098), 2' -methylenebis (4-methyl-6-tert-butylphenol) (antioxidant 2246). The heat stabilizer comprises barium stearate, barium laurate, barium ricinoleate, calcium stearate, calcium ricinoleate, zinc stearate and magnesium stearate. The Light stabilizer (Light stabilizer) is an additive of high molecular products (such as plastics, rubber, paint, synthetic fiber), which can shield or absorb the energy of ultraviolet ray, quench singlet oxygen and decompose hydroperoxide into inactive substances, so that the high molecular polymer can eliminate or slow down the possibility of photochemical reaction under the irradiation of Light, and prevent or delay the process of photoaging, thereby achieving the purpose of prolonging the service life of the high molecular polymer products. Can be o-hydroxybenzophenones, benzotriazoles, salicylates, triazines and substituted acrylonitriles.

The degradable material can also be added with other auxiliary agents, including food-grade pigments or dyes. The edible pigment includes red rice, chlorophyll, curcumin, and carotene. The environmentally friendly dye refers to a dye conforming to REACH registration, and generally includes Kayalon polylestisers LW disperse dye, hensmei Cibacet EL disperse dye, BASF company Compact Eco-CC-E (Eco-CC-S) disperse dye, Desida DianixAC-E (UPH) dye. The dye molecules may be completely dissolved in the mixed material or there may be no phase separation after mixing.

The plasticizing process is to pulverize the cellulose acylate into a certain particle size. Then the powder and the plasticizer are mixed evenly. And adding the powder into a double-screw extruder for plasticizing, stretching, cooling and granulating to prepare plasticized particles. The melt index of the above particles was in the range of 80-400g/10min (210 ℃,10 kg weight). The softening temperature of the particles is between 40 ℃ and 120 ℃. Preferably between 50 ℃ and 100 ℃.

The particles can be made into films by a solution method: dissolving cellulose acetate by using a solvent, wherein the solvent can be acetone, methyl ethyl ketone, diacetone alcohol, acetic acid, methyl formate, methyl acetate, ethyl lactate, dimethylformamide, dimethylacetamide, nitromethane, methyl glycol acetate, dichloromethane and methanol mixed solution, tetrahydrofuran, dioxane and dioxolane, adding the plasticizer and the additive, controlling the concentration of the solution to be 2-20%, preferably 4-17%, more preferably 6-14%, and stirring the solution until the solution is transparent and clear. And standing the casting solution for defoaming. And casting or blade-coating the casting solution on a glass substrate, controlling the thickness to be 50-1000 microns, and then drying, separating and rolling to obtain the cellulose acetate membrane. The film thickness is from 1 micron to 800 microns, preferably from 20 microns to 500 microns, more preferably from 50 microns to 250 microns.

The particles can be made into a film through a film blowing process:

the plasticized particles are melted in a single screw extruder at a temperature of 180 ℃ to 230 ℃, preferably 190 ℃ to 220 ℃, and more preferably 200 ℃ to 210 ℃. The method is characterized in that a flat extrusion up-blowing method is adopted, a right-angle head is used, namely the discharging direction of the head is vertical to an extruder, an extruded pipe is annularly upward and is clamped by a herringbone plate after being drawn to a certain distance, the extruded pipe is blown into a bubble pipe by compressed air introduced from the bottom, the transverse size of the bubble pipe is controlled by the amount of the compressed air, the longitudinal size of the bubble pipe is controlled by the drawing speed, and the bubble pipe can be cooled and shaped to obtain the blown film. Calculating a stretch ratio according to the thickness of the extruded pipe orifice film and the finished product film, wherein the stretch ratio is 1: 1-50: 1, preferably 2: 1-40: 1, and more preferably 5: 1-30: 1.

The plasticized particles can also be processed into films:

adding the prepared plastic particles into a single-screw extruder, melting at 180-230 ℃, preferably 190-220 ℃, extruding from a slender neck mold with certain thickness, stretching at a certain stretching ratio to obtain a film with the thickness of 50-500 mu m, cooling, stretching, cutting and rolling to obtain the biodegradable plastic film. The thickness of the extrusion die is 0.2-5mm, preferably 0.5-2 mm. The draw-down ratio is 1: 1-50: 1, preferably 2: 1-10: 1.

The cellulose acetate film and paper may be combined in a variety of ways. One such method is a hot pressing method. After the film and the paper are jointed, the film and the paper are pressed tightly by an extrusion roller under certain pressure, the pressing temperature is 80-180 ℃, preferably 100-160 ℃, and the pressure of the extrusion roller is 0.1-10MPa, preferably 0.2-5MPa, so that the single-sided or double-sided plasticized paper-plastic composite film is prepared.

The cellulose acetate film and the paper can be compounded into a film in a scraping, coating or spraying mode. Dissolving cellulose ester in solvent, wherein the solvent can be acetone, methyl ethyl ketone, diacetone alcohol, acetic acid, methyl formate, methyl acetate, ethyl lactate, dimethylformamide, dimethylacetamide, nitromethane, methyl glycol acetate, dichloromethane methanol mixed solution, tetrahydrofuran, dioxane and dioxolane, and adding the plasticizer and the additive to control the concentration of the solution to be 2-20%, preferably 4-17%, and more preferably 6-14%. Standing and defoaming the cellulose ester solution, uniformly scraping, coating or spraying the cellulose ester solution on a paper surface, heating the paper surface to 30-100 ℃, volatilizing the solvent, and then extruding and finishing the solvent by a pair of rollers to obtain the environment-friendly paper-plastic composite film.

The paper in the paper-plastic composite structure can be paper bag paper, kraft paper, translucent paper, stripe kraft paper, film protection base paper, neutral packaging paper, extensible paper bag paper, tissue packaging paper, common packaging paper, stripe packaging paper, soap packaging paper, packaging base paper, food parchment paper, candy packaging base paper, ice sucker packaging paper, imitation parchment paper, common food packaging paper and oil-proof paper. The thickness of the paper is 20 to 800 microns, preferably 30 to 500 microns, more preferably 50 to 250 microns.

The contact angle between the film and the surface of the ultrapure water is 50-90 degrees, preferably 65-80 degrees.

The film or the composite film can be applied to the field of packaging. If an environment-friendly plasticizer is used, the cellulose acetate paper composite material can be used in food contact applications and packaging fields, such as dinner plates, water cups and food packaging bags.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the degradable paper-plastic composite film of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples. The percentages (%) in the following examples are by weight unless otherwise indicated. The heat distortion temperature was obtained by using a thermomechanical analyzer (TA, TMA-Q400, USA). Melt index was measured on a melt index tester, type Ceast MF20, under the conditions 210 ℃ and a weight of 10kg, unless otherwise stated. The surface tension tester is DCAT25, and the dynamic contact angle test method is used for testing the contact angle of the membrane material and the ultrapure water at 20 ℃.

The present invention will be further described with reference to specific formulations and examples.

As shown in fig. 1, the present invention includes a paper substrate, i.e., paper 1, an upper cover film 21 and a lower cover film 22; the paper 1 is respectively coated by an upper covering film 21 and a lower covering film 22 from the upper direction and the lower direction, so that a paper-plastic composite structure is formed; the paper can be paper bag paper, kraft paper, translucent paper, stripe kraft paper, film protection base paper, neutral packaging paper, stretch paper bag paper, tissue packaging paper, common packaging paper, stripe packaging paper, soap packaging paper, packaging base paper, food parchment paper, candy packaging base paper, ice sucker packaging paper, imitation parchment paper, common food packaging paper, oil-proof paper and the like. The thickness of the paper is 20 to 800 microns, preferably 30 to 500 microns, more preferably 50 to 250 microns.

The upper covering film 21 and the lower covering film 22 adopt the cellulose acetate or the derivative film thereof, and have various options as described above; in addition, fig. 1 shows a paper-plastic composite film structure with two-sided plasticization, which may also be a paper-plastic composite film structure with one-sided plasticization and a paper-plastic composite film structure with local plasticization according to actual needs; in some cases, the paper substrate, the cellulose acetate or the derivative film thereof may have a composite structure, and various combinations thereof may be performed to generate various structures … …, which are not described in detail herein.

Example 1

1) Cellulose acetate was pulverized in a mill into a powder having a particle size of 200 μm (degree of substitution of acetyl group: 2.45, intrinsic viscosity: 1.54dL/g, number average molecular weight: 37000, weight average molecular weight: 63000, Mw/Mn: 1.7).

2) 70 parts of cellulose acetate powder is dried at 120 ℃ for 2 hours, and then is uniformly mixed with 30 parts of glycerol triacetate and 10101 parts of antioxidant on a mixer.

3) The powder is added into a double-screw extruder for plasticizing and extruding, the temperature of 6 heating zones of the double-screw extruder is 130/150/165/180/190/190, the head temperature is 190 ℃, the head pressure of the extruder is 0.2-0.4Mpa, and the rotating speed of the screw is 50-90 r/min.

4) And (3) stretching, cooling and granulating the extruded filaments to prepare the cellulose acetate plastic particles. The melt index was 100g/10 min.

Example 2

2) 70 parts of cellulose acetate powder was dried at 120 ℃ for 2 hours, and then mixed with 30 parts of triethylene glycol dimethyl ether and 10101 parts of antioxidant in a mixer.

4) And (3) stretching, cooling and granulating the extruded filaments to prepare the cellulose acetate plastic particles. The melt index was 310g/10 min.

Example 3

1) The particles obtained in example 1 were fed into a twin-screw extruder, heated at 200 ℃ and extruded through a die having a thickness of 1mm to form a film.

2) The resulting film was stretched 5 times by a stretching roll to obtain a film having a thickness of 100 μm.

The contact angle of the prepared film was 76 degrees.

Example 4

1) The particles of example 2 were fed into a twin-screw extruder, heated at 200 ℃ and extruded through a die having a thickness of 1mm to form a film.

2) The film was stretched 10 times by a stretching roll to obtain a film having a thickness of 50 μm.

The contact angle of the resulting film was 68 degrees.

Example 5

1) The film of example 3 and paper bag paper with a thickness of 50 μm were pressed in combination, with a press roll temperature of 150 ℃ and a press pressure of 0.5 MPa.

2) And cutting and rolling the composite die to obtain the cellulose acetate composite film with the thickness of 130 mu m.

Example 6

1) The film of example 4 was placed on both upper and lower surfaces of a paper bag having a thickness of 100 μm, and the paper bag was pressed together in a roll press at a pressing roll temperature of 150 ℃ and a pressing pressure of 0.7 MPa.

2) The composite die is cut and rolled to obtain the cellulose acetate composite film with the thickness of 120 mu m.

Example 7

1) The plasticized particles of example 1 were passed through a single screw extruder at a melting temperature of 210 ℃.

2) Adopting a flat extrusion up-blowing method, using a right-angle machine head, extruding a pipe ring upwards, drawing, blowing the extruded pipe into a bubble pipe by compressed air introduced from the bottom of the extruded pipe, and controlling the drawing ratio to be 50: 1.

3) The bubble tubes are collected by a herringbone plate, and the film with the thickness of 50 mu m can be obtained after cooling and shaping.

The contact angle of the resulting film was 76 degrees.

Example 8

1) The blown film of example 7 was cut into a single-layer film having a thickness of 50 μm.

2) The film and paper bag paper with the thickness of 100 mu m are pressed compositely, the temperature of a pressing roller is 150 ℃, and the pressing pressure is 0.5 MPa.

3) The composite die is cut and rolled to obtain the cellulose acetate composite film with the thickness of 120 mu m.

Example 9

1) 30 parts of cellulose acetate (degree of substitution with acetyl group: 2.45, intrinsic viscosity: 1.54dL/g, number-average molecular weight: 37000, weight-average molecular weight: 63000, Mw/Mn: 1.7), 70 parts of triacetin, and 10861 parts of antioxidant were dissolved in an acetone solution at a controlled concentration of 6%.

2) The solution was uniformly sprayed onto paper bags of 100 μm thickness.

3) Most of the solvent is volatilized from the composite paper at the temperature of 50 ℃.

4) And (3) compacting and finishing the composite paper on a roller press with the pressure of 0.4MPa and the temperature of 100 ℃, and rolling to obtain the composite die with the thickness of 110 mu m.

Example 10

1) 30 parts of cellulose acetate (degree of substitution with acetyl group: 2.45, intrinsic viscosity: 1.54dL/g, number-average molecular weight: 37000, weight-average molecular weight: 63000, Mw/Mn: 1.7), 70 parts of triacetin, and 10861 parts of antioxidant were dissolved in an acetone solution at a controlled concentration of 12%.

2) The solution was knife coated evenly onto paper bags of 100 μm thickness.

4) And (3) compacting and finishing the composite paper on a roller press with the pressure of 0.4MPa and the temperature of 100 ℃, and rolling to obtain the composite die with the thickness of 140 mu m.

The foregoing description and description of the embodiments are provided to facilitate understanding and application of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications can be made to these teachings and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above description and the description of the embodiments, and those skilled in the art should be able to make modifications and alterations without departing from the scope of the present invention.

Claims

1. A biodegradable paper-plastic composite structure, comprising:

at least one cellulose acetate or derivative film thereof;

a paper substrate;

2. The biodegradable paper-plastic composite structure according to claim 1, wherein the cellulose acetate or its derivative backbone is polysaccharide cellulose containing organic substituent groups, and the formula or structure is as follows:

wherein

3. A biodegradable paper-plastic composite structure according to claim 1, characterized in that said cellulose acetate or derivative is cellulose diacetate, cellulose acetate propionate or cellulose acetate butyrate.

4. A biodegradable paper-plastic composite structure according to claim 1 or 2, characterized in that: when the substituent of the cellulose acetate and the derivative thereof is acyl, the value of X + Y + Z is 1.5-2.8.

5. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the cellulose acetate and the derivatives thereof have the molecular weight of 10000-120000 Dalton.

6. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the molecular weight of the cellulose acetate and the derivatives thereof is 20000-100000 Dalton.

7. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the cellulose acetate and the derivatives thereof have the molecular weight of 25000-90000 Dalton.

8. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the intrinsic viscosity of the cellulose acetate and the derivatives thereof is 1.2-1.8 dL/g.

9. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the intrinsic viscosity of the cellulose acetate and the derivatives thereof is 1.25-1.75 dL/g.

10. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the intrinsic viscosity of the cellulose acetate and the derivatives thereof is 1.35-1.7 dL/g.

11. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the plasticizer is a phthalate compound.

12. A biodegradable paper-plastic composite structure according to claim 11, characterized in that: the phthalate ester compound comprises dimethyl phthalate; diethyl phthalate; di (2-ethylhexyl) phthalate, dibutyl phthalate and diethyl phthalate, dioctyl phthalate, butyl benzyl phthalate; diisononyl phthalate diisooctyl phthalate, diisobutyl phthalate, diisooctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dicyclohexyl phthalate.

13. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: plasticizers, including one or a combination of more of glycerides, citrates, acetylcitrate esters, ethylene glycol oligomers, propylene glycol oligomers, ethylene glycol propylene glycol copolymers, epoxidized vegetable oil esters, and other fatty acid ester plasticizers, are also included.

14. A biodegradable paper-plastic composite structure according to claim 11, characterized in that: the plasticizer is a glyceride plasticizer having the following molecular structure:

wherein,

R₃,R₄,R₅＝H,

n＝0～16。

15. a biodegradable paper-plastic composite structure according to claim 13, characterized in that:

the plasticizer is:

R₁O(CH2CH2O)_nR₂

wherein,

R₁，R₂＝H，CH₃，

n＝1，2，3，4，5。

16. a biodegradable paper-plastic composite structure according to claim 13, characterized in that: the citric acid esters and acetyl tributyl citrate plasticizers refer to compounds with the following molecular structures:

wherein,

R₆＝H，OH，

R₇，R₈，R₉＝CH₃，C₂H₅，C₃H₇，C₅H₁₂，C₇H₁₅。

17. a biodegradable paper-plastic composite structure according to claim 13, characterized in that: the citric acid ester comprises triethyl citrate, tripropyl citrate and tributyl citrate.

18. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the acetyl citrate comprises acetyl triethyl citrate, acetyl tripropyl citrate and acetyl tributyl citrate.

19. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the citric acid ester plasticizer and the triacetyl glycerine ester plasticizer are mixed for use.

20. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the acetylcitrate plasticizer and the triacetin plasticizer are mixed for use.

21. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the ethylene glycol oligomer, the propylene glycol copolymer or the ethylene glycol propylene glycol copolymer refers to the ethylene glycol oligomer, the propylene glycol copolymer or the ethylene glycol propylene glycol copolymer with the molecular weight of between 150-1500 g/mol.

22. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the end group of the ethylene glycol oligomer is hydroxyl; the molecular weight of the PEG plasticizer is 200-1500 g/mol.

23. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the molecular weight of the PEG plasticizer is 250-800 g/mol.

24. A biodegradable paper-plastic composite structure according to claim 13, characterized in that:

the terminal hydroxyl groups of the ethylene glycol oligomer, the propylene glycol oligomer or the ethylene glycol-propylene glycol copolymer are substituted by alkyl or carboxylic acid groups, including triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and triethylene glycol diacetate.

25. A biodegradable paper-plastic composite structure according to claim 13, characterized in that: the epoxy vegetable oil ester comprises epoxy soybean oil, epoxy butyl stearate, epoxy butyl furoate, epoxy butyl soybean oleate, epoxy butyl cottonseed oleate, epoxy butyl rapeseed oleate, epoxy butyl tallate and epoxy butyl xanthate oleate;

the fatty acid ester plasticizer comprises one or more of 2,2, 4-trimethyl-1, 3-pentanediol diisobutyrate, 2, 2-dimethyl-1, 3-propylene glycol, pentaerythritol tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], sorbitan monolaurate, glycerol monostearate, glycerol mono-laurate, dilaurate, di (2-ethylhexyl) adipate, diisononyl adipate, dodecanoate of a polymer of adipic acid and 1, 2-propylene glycol, isosorbide dicaprylate or bio-based polycaprolactone.

26. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: also includes non-reactive inorganic inactive particles; by "inorganic inactive without reactivity" is meant that the particles do not chemically react with cellulose acetate or its reaction products at temperatures between room temperature and 100 ℃.

27. A biodegradable paper-plastic composite structure according to claim 26, characterized in that: the shape of the particles comprises spherical, spheroidal, pie-shaped, flake-shaped, ribbon-shaped, acicular, polygonal, faceted, or random; the particle size range of the particles is 10-400 nm.

28. A biodegradable paper-plastic composite structure according to claim 27, characterized in that: the particles comprise more than one of titanium dioxide, aluminum oxide, zirconium oxide, glass beads, silicon dioxide, silicate spheres, kaolin particles, sucrose powder, dextrin, lactose, powdered sugar, glucose, mannitol, starch, methyl cellulose, ethyl cellulose, microcrystalline cellulose, polylactic acid, polyhydroxybutyrate, poly epsilon-caprolactone, polyglycolic acid and polyhydroxyalkanoate, crushed grains and aluminum, iron, copper and calcium sulfate.

29. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: also comprises an antioxidant, a heat stabilizer and an ultraviolet light stabilizer, and is used for preventing the strength and the toughness of the polymer material from losing due to oxidative degradation.

30. A biodegradable paper-plastic composite structure according to claim 29, characterized in that: the antioxidant comprises pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], N-octadecyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, tris (2, 4-di-tert-butylphenyl) phosphite, 4' -thiobis (6-tert-butyl-3-methylphenol), N ' -bis- (3- (35-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine and 2,2' -methylenebis (4-methyl-6-tert-butylphenol).

31. A biodegradable paper-plastic composite structure according to claim 29, characterized in that: the heat stabilizer comprises barium stearate, barium laurate, barium ricinoleate, calcium stearate, calcium ricinoleate, zinc stearate and magnesium stearate.

32. A biodegradable paper-plastic composite structure according to claim 29, characterized in that: the ultraviolet light stabilizer is used for shielding or absorbing energy of ultraviolet rays and comprises o-hydroxybenzophenones, benzotriazoles, salicylates, triazines and substituted acrylonitrile.

33. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the cellulose acetate or derivative thereof is present in an amount of between 55% and 99%.

34. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the film has a thickness of 1 to 800 microns.

35. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the film has a thickness of 20 to 500 microns.

36. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the film has a thickness of 50 to 250 microns.

37. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the softening temperature of the cellulose acetate and the derivative film thereof is between 40 ℃ and 150 ℃.

38. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the softening temperature of the cellulose acetate and the derivative film thereof is between 60 ℃ and 120 ℃.

39. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the composite structure is coated on one or both sides with: the film having a thickness of 1 to 800 microns.

40. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the composite structure is coated on one or both sides with: the film having a thickness of 20 to 500 microns.

41. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the composite structure is coated on one or both sides with: the film having a thickness of 50 to 250 microns.

42. A biodegradable paper-plastic composite structure according to claim 1, characterized in that: the paper base material comprises paper bag paper, kraft paper, stripe kraft paper, film protection base paper, neutral packaging paper, common packaging paper, stripe packaging paper, soap packaging paper, packaging base paper, food parchment paper, candy packaging base paper, imitation parchment paper, common food packaging paper or oil-proof paper.

43. A biodegradable paper-plastic composite structure according to claim 42, characterized in that: the thickness of the paper substrate is 20 micrometers to 800 micrometers.

44. A biodegradable paper-plastic composite structure according to claim 42, characterized in that: the paper substrate has a paper thickness of 30 to 500 microns.

45. A biodegradable paper-plastic composite structure according to claim 42, characterized in that: the paper substrate has a paper thickness of 50 to 250 microns.