CN112795055A

CN112795055A - Degradable pipe and preparation method and application thereof

Info

Publication number: CN112795055A
Application number: CN202011609122.2A
Authority: CN
Inventors: 梁银春; 孙利辉; 杨占平; 苏凯; 苏日挺; 董德俊; 陈晓璐; 沈晶晶
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: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-05-14

Abstract

A degradable pipe comprises at least one cellulose or its derivative; the content of the organic micromolecular compound in the pipe is less than 1 percent. The preparation method of the degradable pipe comprises the steps of blending cellulose or derivatives thereof with a plasticizer, and then obtaining a modified material through extrusion and granulation; processing the modified material into a pipe by a blow molding or extrusion process; and removing the plasticizer in the pipe to obtain the pipe with heat resistance. The pipe can be used in the fields of food and tobacco, including cigarette filter sticks, beverage straws and the like, and can be naturally degraded after being used because the production raw materials come from nature, so that the problem of environmental pollution caused by the use of pipe products can be eliminated or reduced.

Description

Degradable pipe and preparation method and application thereof

Technical Field

The invention belongs to the technical field of degradable polymer products, and relates to a cellulose-based pipe and a preparation method thereof.

Background

Along with the development and application of petroleum-based plastics, great convenience is brought to human life, but great environmental problems are brought at the same time. The daily necessities such as plastic bags, plastic packages, disposable polypropylene snack boxes, plastic tableware and cup trays, plastic beverage bottles, yogurt cups and the like are used in large quantities, but the natural degradation rate is slow, and the environmental pollution is caused. Traditional petroleum-based plastics are difficult to degrade in the environment, such as PP, PE, and their application to plastic packaging and disposable tableware can generate a large amount of plastic particles, causing irreversible damage to the ecological environment. 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.

By adding the environment-friendly material into the plastic material, the usage amount of the plastic material can be reduced. The additive comprises inorganic salt such as calcium carbonate, or natural polymer such as wood flour and starch. 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. CN110527191A provides an inorganic degradable plastic master batch material, which comprises the following components: 56-72% by mass of calcium carbonate ore powder; 3-10% by mass of polyethylene; 18-30% by mass of polypropylene; 2-5% by mass of glass fibers; and 3-5% by mass of an auxiliary agent. 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. The plastic product produced by the method can be quickly disintegrated in the environment, but the resin base 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.

To reduce the environmental problems associated with plastic applications, many new materials for food service items have been tried, including renewable wood, wood pulp, wood chips, and cardboard. However, since paper materials are not suitable for some applications where water is in contact with the paper materials, many improvements to paper materials are needed.

Solving the problem of environmental pollution in nature requires materials that can be completely biodegradable, such as starch plastics, polylactic acid (PLA), Polyhydroxyalkanoate (PHA), which can be rapidly degraded in the natural environment. The problem is that starch plastic and PLA need to be processed by edible raw materials, and the problem of food competition with people exists. PHA is an intracellular polyester synthesized by microorganisms and has low biosynthesis efficiency.

The degradable materials commonly used for preparing the straw comprise paper, PLA containing environment-friendly additives, plant fiber materials (rice, sugarcane and wheat straw), seaweed and the like, wherein the PLA is mostly used as the straw. Apart from cost considerations, PLA has other technical drawbacks as a straw, such as a lower softening temperature, which is not suitable for hot food and beverages.

CN109370180A discloses a degradable PLA biomaterial for straw manufacture, comprising: 15-25 parts of polylactic resin, 5-20 parts of polylactide, 1-3 parts of functional auxiliary agent, 0.3-0.7 part of polypropylene flow agent, 10-15 parts of compatibilizer, 5-8 parts of functional master batch, 0.2-0.5 part of antioxidant, 8-12 parts of magnesite modifier, 20-25 parts of epoxy resin, 35-45 parts of high-density polyethylene, 35-55 parts of polycarbonate, 3-8 parts of polyvinyl chloride, 2-10 parts of alkyl aluminum, 5-30 parts of master batch and 20-30 parts of poly (terephthalic acid) -adipic acid-butanediol copolyester.

CN109467777A discloses a degradable PLA biomaterial for manufacturing a straw and a preparation method thereof, wherein the PLA biomaterial adopts the following raw materials in parts by weight: the molecular weight of the polylactic acid PLA is 5-40 ten thousand; the molecular weight of the polyethylene copolymer is 2-25 ten thousand; the molecular weight of the organic metal compound is 0.05-5 ten thousand; the molecular weight of the functional auxiliary agent is 0.2-1 ten thousand; the molecular weight of the bamboo fiber is 8-55 ten thousand.

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. Cellulose acetate has been widely used in the tobacco filtration market as an environmentally degradable material.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a degradable pipe with higher softening temperature and a preparation method thereof.

In order to achieve the above purpose, the solution of the invention is:

the main component of the pipe material of the invention is at least one cellulose acetate or the derivative thereof, and the content of organic micromolecular compounds in the pipe material is less than 1 percent. The organic small molecular compound in the invention is an organic compound with a molecular weight of less than 10000g/mol, and the thermal processing temperature of the organic small molecular compound can be reduced by blending the organic small molecular compound with a cellulose derivative.

The invention adopts cellulose as raw material to prepare 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.

The cellulose derivatives include cellulose ethers; the cellulose includes cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate.

The main chain of the cellulose acetate is composed of 1, 4-beta-D-glucopyranose, 3 hydroxyls at 2, 3 and 6 positions of each glucose ring can be acylated, generally can be replaced by acetyl, propionyl or butyryl, and can be singly or in a plurality of types, the content of each substituent can be controlled according to the requirement, and can be between 0 and 3; the following formula:

wherein

Cellulose acetate production requires cellulose from wood or cotton to be up to 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 solution to prepare 0.25% solution, and the intrinsic viscosity is measured by an Ubbelohde viscometer at 25 ℃.

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 adopted for acetylation, the finished product is cellulose acetate, and the acetyl substitution degree (X + Y + Z) ranges from 1.5 to 2.8, preferably from 1.8 to 2.7, and more preferably from 1.9 to 2.6. The intrinsic viscosity of cellulose acetate is 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 tubing. 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. For example, cellulose diacetate can be dissolved in acetone solvent to make tow for tobacco filtration. The hydroxyl groups of the cellulose are grafted with hydrocarbon and carbonyl functional groups, so that the cellulose material has injection molding processability.

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 commonly used for modifying cellulose acetate includes small molecular compounds such as phthalate esters, citrate esters, glycerols, ethylene glycol oligomers, propylene glycol oligomers, and the like. With the addition of the plasticizer, the heat resistance of the material is reduced. Most of the tubes prepared from the cellulose acetate material modified by the plasticizer have relatively low softening temperature, and cannot meet the use requirement of a heat-resistant environment. The method provided by the invention is to process the modified material into the pipe, and then use water or organic solvent with better compatibility to the plasticizer to remove the plasticizer, so that the national standard of food-contactable materials can be met, and the heat resistance of the pipe can be obviously improved.

Optionally, the pipe of the present invention may further comprise non-reactive inorganic inactive particles, 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 less than 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.

Blow molding is a process suitable for making plastic hollow containers, including polyethylene, polyvinyl chloride, polypropylene, polyester, and the like. The thermoplastic resin is extruded or injection molded to obtain tubular plastic parison, which is hot or heated to soften, and then placed in a split mold, after the mold is closed, compressed air is introduced into the parison to blow the plastic parison to cling to the inner wall of the mold, and after cooling and demolding, various hollow products are obtained. The process for manufacturing blown pipes is in principle very similar to blow moulding of hollow articles, but it does not use a mould and uses air flow, feed and draw ratio to control the diameter and thickness of the pipe. The invention relates to a method for preparing a cellulose acetate or derivative pipe by using thermoplastic plastic particles as raw materials through a blow molding method.

The invention discloses a pipe based on cellulose acetate and derivatives, which is processed by the following steps: 1. the modified material is obtained by blending cellulose or a derivative thereof with a plasticizer and then performing extrusion granulation. 2. The required pipes are processed by blow molding or extrusion processes. 3. And (3) placing the processed pipe in a certain solution system to wash out the micromolecule plasticizer to obtain the heat-resistant pipe.

The specific plasticizing process is to pulverize the cellulose acylate into a particle size of 50-500 μm, preferably 100-300 μm. Mixing the powder 30-90 parts, preferably 50-80 parts, plasticizer 10-60 parts, preferably 20-40 parts, and additive 0-5 parts in a high-speed mixer. And adding the powder into a double-screw extruder for plasticizing, stretching, cooling and granulating to prepare plasticized particles. The plasticizing temperature is 100-250 degrees, preferably 120-230 degrees. The melt index of the particles thus obtained is in the range of 80 to 400g/10 min. The melt index of the material was measured on a melt index tester, model Ceast MF20, under the conditions of 210 ℃ and a weight of 10 kg.

Extruding the modified material in a single screw extruder at the temperature of 185-plus-200 ℃, performing extrusion blow molding through an empty pipe neck mold, obtaining empty pipes with different diameters and wall thicknesses by adjusting the pressure of compressed air, the stretch ratio of the empty pipes and other conditions, performing hot air drying after water cooling, and cutting into pipes with required lengths through a traction cutting machine. In the blow molding process, the pressure of compressed air is 0.2-0.6 MPa. The stretch ratio is (1: 1) - (100: 1), preferably (2: 1) - (40: 1). In the traction cutting process, the cutting length of the pipe is 1 cm to 50 cm; preferably 20 cm to 30 cm.

The hollow pipe has low heat resistance and can only meet the use requirement of lower temperature. The pipe is treated by a certain eluent to remove organic micromolecule compounds, and the pipe with higher softening temperature can be obtained.

The eluent refers to a solution of water or an organic solvent with good compatibility with small organic molecular compounds, and includes but is not limited to alcohols, fatty acid esters, ketones, supercritical carbon dioxide and other compounds.

Optionally, the alcohol in the eluent comprises one or more of methanol, ethanol, propanol, isopropanol or their aqueous solution.

Alternatively, the alcohol eluent can be a pure solvent or an aqueous solution thereof, and a mixed composition of different alcohol solvents can also be used. Optionally, when an aqueous alcohol solution is used as the eluent, the mass fraction of the alcohol is 5% to 100%, preferably 20% to 99%.

Alternatively, a mixed solvent of different alcohols is used as the eluent. Optionally, a mixed solvent of methanol, ethanol and isopropanol is used as eluent, and the mass ratio of methanol, ethanol and isopropanol is 5:90:5 respectively. Optionally, the fatty acid esters in the eluent include one or more of methyl formate, ethyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, and the like. When the fatty acid ester compound is used as an eluent, the solvent has a swelling effect on the cellulose derivative, is easy to show a pipe swelling phenotype, and can be used by combining fatty alkane and ester of C3-C8. Alternatively, ethyl acetate is used in combination with petroleum ether, and the two components may be used in a mass ratio of 9:1 to 1: 9.

Due to the adoption of the technical scheme, the invention at least has the following beneficial effects: through the treatment of the eluent, the pipe can meet the requirement that the softening temperature is higher than 100 ℃ and the use requirement of higher temperature can be met. It is worth to say that the pipe can meet the standard of the national standard GB31604.2 for the total migration of food contact materials. Because the raw materials for producing the pipe are natural, the pipe can be naturally degraded after being used, and the problem of environmental pollution caused by the use of pipe products can be eliminated or reduced. The pipe material can be used in the fields of food and tobacco.

Detailed Description

The invention is further illustrated by the following specific formulations and examples.

The percentages (%) in the following examples are by weight unless otherwise indicated. The softening temperature was measured by using a thermomechanical analyzer (TA, U.S.A. TMA-Q400). 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 tensile and bending tests were carried out according to standards ISO527 (GB/T1040.3-2006) and ISO178 (GB/T9341-. The test was carried out using an electronic universal tester (CMT5245, New Miss metrology technologies, Inc., Shenzhen) at room temperature at a tensile rate of 50mm/min and a bending rate of 2mm/min, respectively.

Example 1

The implementation steps of this example are as follows:

700g of cellulose acetate (degree of substitution of acetyl group: 2.45, intrinsic viscosity: 1.54dL/g, number-average molecular weight: 37000, weight-average molecular weight: 63000,) was dried at 120 ℃ for 2 hours, and then thoroughly mixed with 300g of triacetin in a mixer at 800 rpm for 20 minutes, followed by pelletization using a twin-screw extruder. The temperature of 6 heating zones of the double screw extruder is 130/150/165/180/190/195, the head temperature is 190 ℃, the head pressure of the extruder is 0.2-0.4Mpa, the screw rotating speed is 50-90 r/min, and the material is plasticized, extruded into strand silk, cooled and granulated to obtain plasticized particles. The melt index was 100g/10 min. Tensile strength of 27.4MPa and breaking elongation of 37.3 percent.

Extruding the mixed material at 185-200 ℃ by using a single screw extruder, carrying out extrusion blow molding through an empty tube mouth mold, carrying out cooling and hardening through a cooling water bath (4m) at 30 ℃ under the condition that the compressed air pressure is 0.3Mpa and the stretching ratio is controlled to be 1.2: 1, drying by hot air to obtain an empty tube with the outer diameter of 5mm and the wall thickness of 0.2mm, and cutting the empty tube into a colorless transparent empty tube sample A with the length of 160mm by a traction cutting machine (270 rpm).

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A into 100ml of 50% ethanol water solution, immersing for about 2 hours at the water bath temperature of 50 ℃, taking out the tube from the ethanol solution, and blowing the tube for 2 hours by using a fan to obtain an empty tube sample B.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A into 100ml of 60% ethanol water solution, immersing for about 2 hours at the water bath temperature of 50 ℃, taking out the tube from the ethanol solution, and blow-drying for 2 hours by using a fan to obtain an empty tube sample C.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A into 100ml of 70% ethanol water solution, immersing for about 2 hours at the water bath temperature of 50 ℃, taking out the tube from the ethanol solution, and blowing the tube for 2 hours by using a fan to obtain an empty tube sample D.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A into 100ml of 80% ethanol water solution, immersing for about 2 hours at the water bath temperature of 50 ℃, taking out the tube from the ethanol solution, and blowing the tube for 2 hours by using a fan to obtain an empty tube sample E.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A into 100ml of 95% ethanol water solution, immersing for about 1h at the water bath temperature of 60 ℃, taking out the tube from the ethanol solution, and blow-drying for 2h by using a fan to obtain an empty tube sample F.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A in 100ml of absolute ethyl alcohol at the water bath temperature of 55 ℃ for about 1h, taking out the tube from the ethanol solution, and blow-drying the tube for 2h by using a fan to obtain an empty tube sample G.

And (3) optionally selecting 5 tubes of the tube A, immersing the tube A in 100ml of methanol at the water bath temperature of 50 ℃ for about 2H, taking out the tube from the ethanol solution, and blow-drying the tube for 2H by using a fan to obtain an empty tube sample H.

And (2) optionally selecting 5 tubes of the tube A, immersing the tubes into 100ml of mixed solution of methanol, ethanol and isopropanol (the mass ratio is 5:90:5), soaking the tubes for about 2 hours at the water bath temperature of 50 ℃, taking out the tubes from the ethanol solution, and blow-drying the tubes for 2 hours by using a fan to obtain an empty tube sample I.

The softening temperature and the total migration amount of the empty tube samples A to I were measured, respectively, and the results are shown in Table 1. The results show that the softening temperature of the sample subjected to elution treatment is greatly increased, and the sample has a good heat-resistant effect. Meanwhile, the total migration volume of the empty pipe sample meets the requirement of food contactable materials according to the test method of GB 31604.8.

TABLE 1 softening temperature and Total migration of different empty tube samples

Example 2

The implementation steps of this example are as follows:

1. 700g of cellulose acetate (degree of substitution of acetyl group: 1.75, intrinsic viscosity: 1.35dL/g) (number-average molecular weight: 25000, weight-average molecular weight: 42000) was dried at 120 ℃ for 2 hours, and then thoroughly mixed with 300g of triacetin and 3.5g of titanium dioxide in a mixer at 800 rpm for 20 minutes, followed by pelletization using a twin-screw extruder. 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, the screw rotating speed is 50-90 r/min, and the material is plasticized, extruded into strand silk, cooled and granulated to obtain plasticized particles. The melt index was 111g/10 min.

2. Extruding the mixed material at 185-200 ℃ by using a single screw extruder, carrying out extrusion blow molding through an empty tube die, controlling the pressure of compressed air to be 0.3Mpa and the stretching ratio to be 1.2: 1, cooling and hardening through a cooling water bath (4m) at 30 ℃, drying by hot air to obtain an empty tube with the outer diameter of 5.8mm and the wall thickness of 0.3mm, and cutting the empty tube into a white empty tube with the length of 120mm by a traction cutting machine (270 revolutions per minute).

3. And (3) placing 5 tubes into 100ml of 50% ethanol water solution, soaking for about 2 hours at the water bath temperature of 50 ℃, taking out the tubes from the ethanol solution, and blow-drying for 2 hours by using a fan to obtain the target white tubes, wherein the thermal deformation temperature of the tubes is 158 ℃. According to the test method of the national standard GB31604.8, the total migration volume of the pipe is 7.6mg/dm²And a total migration standard of the composite food contact material standard.

Example 3

The implementation steps of this example are as follows:

1. 700g of cellulose acetate (degree of substitution of acetyl group: 2.50, intrinsic viscosity: 1.7dL/g, number average molecular weight: 45000, weight average molecular weight: 73000,) was dried at 120 ℃ for 2 hours, thoroughly mixed with 300g of triethyl citrate in a mixer at 800 rpm for 20 minutes, and then pelletized using a twin-screw extruder. The temperature of 6 heating zones of the double screw extruder is 130/150/165/180/190/195, the head temperature is 195 ℃, the head pressure of the extruder is 0.2-0.4Mpa, the rotating speed of the screw is 50-90 r/min, and the material is plasticized, extruded into strand silk, cooled and granulated to obtain plasticized particles. The melt index was 102g/10 min.

2. Extruding the mixed material at 185-200 ℃ by using a single screw extruder, carrying out extrusion blow molding through an empty tube mouth mold, carrying out cooling and hardening through a cooling water bath (4m) at 30 ℃ under the condition that the compressed air pressure is 0.3Mpa and the stretching ratio is controlled to be 1.2: 1, drying by hot air to obtain an empty tube with the outer diameter of 7mm and the wall thickness of 0.25mm, and cutting the empty tube into a colorless transparent empty tube with the length of 120mm through a traction cutting machine (270 r/min).

3. And (2) placing 10 tubes into 100ml of ethyl acetate/petroleum ether (mass ratio of 80:20) mixed solution, soaking for about 2 hours at the water bath temperature of 50 ℃, taking out the tubes from the ethanol solution, and blow-drying for 2 hours by using a fan to obtain the target heat-resistant tubes, wherein the heat deformation temperature of the tubes is 152 ℃. According to the test method of the national standard GB31604.8, the total migration volume of the pipe is 7.6mg/dm²And a total migration standard of the composite food contact material standard.

Example 4

The implementation steps of this example are as follows:

1. 700g of cellulose acetate (degree of substitution of acetyl group: 2.45, intrinsic viscosity: 1.54dL/g, number-average molecular weight: 37000, weight-average molecular weight: 63000,) was dried at 120 ℃ for 2 hours, thoroughly mixed with 240g of triacetin and 60g of tributyl citrate in a mixer at 800 rpm for 20 minutes, and then pelletized using a twin-screw extruder. The temperature of 6 heating zones of the double screw extruder is 130/150/165/180/190/195, the head temperature is 195 ℃, the head pressure of the extruder is 0.2-0.4Mpa, the rotating speed of the screw is 50-90 r/min, and the material is plasticized, extruded into strand silk, cooled and granulated to obtain plasticized particles. The melt index was 108g/10 min.

2. Extruding the mixed material at 185-200 ℃ by using a single screw extruder, carrying out extrusion blow molding through a hollow pipe die, controlling the pressure of compressed air to be 0.3Mpa and the stretching ratio to be 1.1: 1, cooling and hardening through a cooling water bath (4m) at 30 ℃, drying by hot air to obtain a hollow pipe with the outer diameter of 7mm and the wall thickness of 0.3mm, and cutting the hollow pipe into a milky hollow pipe with the length of 120mm through a traction cutting machine (270 revolutions per minute).

3. And (2) placing 5 tubes into 100ml of mixed solution of isopropyl acetate/cyclohexane (mass ratio of 70:30), soaking for about 2 hours at the water bath temperature of 45 ℃, taking out the tubes, and blow-drying for 2 hours by using a fan to obtain the target heat-resistant tubes, wherein the heat deformation temperature of the tubes is 155 ℃. According to the test method of the national standard GB31604.8, the total migration volume of the pipe is 7.3mg/dm2, and the total migration volume standard of the composite food contact material standard.

Example 5

The implementation steps of this example are as follows:

1. 700g of cellulose acetate (degree of substitution of acetyl group: 2.05, intrinsic viscosity: 1.45dL/g) was dried at 120 ℃ for 2 hours, and then thoroughly mixed with 258g of triacetin in a mixer at 800 rpm for 20 minutes, followed by pelletization using a twin-screw extruder. The temperature of 6 heating zones of the double screw extruder is 130/150/165/180/190/195, the head temperature is 195 ℃, the head pressure of the extruder is 0.2-0.4Mpa, the rotating speed of the screw is 50-90 r/min, and the material is plasticized, extruded into strand silk, cooled and granulated to obtain plasticized particles. The melt index was 96g/10 min.

2. Extruding the mixed material at the temperature of 195-plus-200 ℃ by using a single screw extruder, carrying out extrusion blow molding through an empty tube mouth mold, carrying out cooling and hardening through a cooling water bath (4m) at the temperature of 30 ℃ under the condition that the compressed air pressure is 0.3Mpa and the stretching ratio is controlled to be 1.2: 1, drying by hot air to obtain an empty tube with the outer diameter of 7mm and the wall thickness of 0.3mm, and cutting the empty tube into a transparent empty tube with the length of 100mm by using a traction cutting machine (270 r/min).

3. And (2) placing 5 tubes into 100ml of mixed solution of ethyl acetate/n-pentane (mass ratio of 7:3), soaking for about 2 hours at the water bath temperature of 45 ℃, taking out the tubes, and blow-drying for 2 hours by using a fan to obtain the target heat-resistant tubes, wherein the heat deformation temperature of the tubes is 152 ℃. According to the test method of the national standard GB31604.8, the total migration volume of the pipe is 8.1mg/dm2, and the total migration volume standard of the composite food contact material standard.

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 make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. A degradable tubing characterized by:

a) the components of the cellulose-cellulose composite at least contain one kind of cellulose or a derivative thereof;

b) the content of the organic small molecular compound in the pipe component is less than 1%.

2. The degradable tubing of claim 1, wherein: the organic small molecular compound has a molecular weight of less than 10000g/mol, and can reduce the thermal processing temperature when being blended with cellulose or derivatives thereof; preferably, the organic small molecule compound comprises a plasticizer, preferably one or more combinations of triacetin, tripropionin, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, ethylene glycol oligomers, propylene glycol oligomers, ethylene glycol propylene glycol copolymers.

3. The degradable tubing of claim 1, wherein the cellulose or derivative thereof is a polysaccharide cellulose comprising organic substituent groups of the formula or structure:

4. the degradable tubing of claim 1, wherein: the cellulose derivatives include cellulose ethers; preferably, the cellulose comprises cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate.

5. The degradable tubing of claim 3, wherein: when the substituent of the cellulose and the derivative thereof is acyl, the value of X + Y + Z is 1.5-2.8.

6. The degradable tubing of claim 1, wherein: the cellulose and the derivatives thereof have the molecular weight of 10000-120000 Dalton; preferably, the molecular weight is 20000-; more preferably, its molecular weight is 25000-.

7. The degradable tubing of claim 1, wherein: the inherent viscosity of the cellulose and the derivatives thereof is 1.2-1.8dL/g, preferably 1.25-1.75dL/g, and more preferably 1.35-1.7 dL/g.

8. The degradable tubing of claim 1, wherein: the components can also comprise inorganic inactive particles without reactivity; the term "unreactive inorganic inactive" means that the particles do not chemically react with the cellulose acetate or reaction products thereof at temperatures between room temperature and 100 ℃; the shape of the particles includes spherical, spheroidal, pie-shaped, flake-shaped, ribbon-shaped, acicular, polygonal, faceted, or random.

9. The degradable tubing of claim 8, wherein: the particle size range of the particles is 10-400 nm; the mass fraction of the particles in the mixed material is less than 10%.

10. The degradable tubing of claim 8, wherein: the inorganic inactive particles comprise more than one of titanium dioxide, alumina, zirconia, 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, polyhydroxyalkanoate, crushed grains and aluminum, iron, copper and calcium sulfate.

11. The degradable tubing of claim 1, wherein: the composite material 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; alternatively, the antioxidant comprises pentaerythritol tetrakis [ β - (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, 2' -methylenebis (4-methyl-6-tert-butylphenol); optionally, the thermal stabilizer comprises barium stearate, barium laurate, barium ricinoleate, calcium stearate, calcium ricinoleate, zinc stearate, magnesium stearate; alternatively, the light stabilizer is used for shielding or absorbing energy of ultraviolet rays, and comprises o-hydroxybenzophenones, benzotriazoles, salicylates, triazines, substituted acrylonitriles; optionally, other adjuvants including food grade pigments or dyes which are completely soluble in the mixed materials or which do not phase separate after mixing; optionally, the food grade color or dye includes red yeast, chlorophyll, curcumin, carotene, for example.

12. The degradable tubing of claim 1, wherein: the softening temperature of the pipe is higher than 100 ℃; preferably, the thickness of the pipe wall is 0.02-0.7mm, and the outer diameter is 2-50 mm.

13. A method of making the degradable tubing of any one of claims 1-12, wherein: blending cellulose or derivatives thereof with organic micromolecular compounds, and then extruding and granulating to obtain a modified material;

processing the modified material into a pipe by a blow molding or extrusion or injection molding process;

and removing the organic small molecular compounds in the pipe to obtain the pipe with heat resistance.

14. The method of making the degradable tubing of claim 13, comprising the steps of:

(1) mixing cellulose acetate or derivatives thereof with an organic small molecular compound, and granulating by using an extruder under the condition of heating;

(2) processing the master batch particles prepared by the method in the step (1) into a pipe by a blow molding or extrusion process;

(3) removing organic small molecular compounds from the pipe obtained in the step (2) to obtain a pipe with heat resistance;

the organic small molecule compound refers to a plasticizer, preferably one or more of triacetin, tripropionin, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, ethylene glycol oligomer, propylene glycol oligomer and ethylene glycol-propylene glycol copolymer.

15. The method of making a degradable pipe of claim 13, wherein: adding the master batch particles prepared by the method in the step (1) into a feeding funnel of an extruder, heating a heating section of the extruder, and introducing airflow into a hollow pipe to form a molten cellulose pipe; and guiding the molten cellulose pipe into a cooling water pool, cooling, drawing the cooled cellulose pipe onto a traction wheel, and cutting the cellulose pipe according to a preset length.

16. The method of making a degradable pipe of claim 13, wherein: and (3) removing the organic small molecular compounds in the step (2) by soaking the pipe obtained in the step (2) into an elution solution.

17. The method of making a degradable tubing of claim 16, wherein: the elution solution refers to water or an organic solvent with a good dissolving effect on the organic small molecular compound, and includes but is not limited to alcohols, fatty acid esters, ketones and supercritical carbon dioxide.

18. The method of manufacturing according to claim 16, wherein: the concentration of the elution solution is 5% -100%, the preferred concentration is 20% -98%, and the more preferred concentration is 40% -95%.

The method of making a degradable tubing of claim 16, wherein: the soaking temperature is 25-80 ℃, the preferred temperature is 30-60 ℃, and the more preferred temperature is 35-55 ℃.

19. The method of making a degradable tubing of claim 17, wherein: the alcohol comprises one or more of methanol, ethanol, propanol and isopropanol or water solution thereof.

20. The method of making a degradable tubing of claim 17, wherein: the fatty acid ester comprises one or more of methyl formate, ethyl acetate, propyl acetate and isopropyl acetate.

21. Use of the degradable tubing of any one of claims 1-20 in a cigarette filter rod.

22. Use of the degradable tubing of any one of claims 1 to 20 in a drinking straw.