CN107936186B - 3D printing wire and preparation method thereof - Google Patents

Abstract

The invention relates to a blend 3D printing wire material, which mainly solves the technical problems that the thermoplastic cellulose is high in viscosity and poor in product toughness in the low-temperature processing process in the prior art and is difficult to apply to the field of 3D printing, and the graft modified thermoplastic cellulose and aliphatic polyester blend comprises the following components in parts by mass by adopting the 3D printing wire material containing the graft modified thermoplastic cellulose and aliphatic polyester blend: (1)20 to 80 parts of thermoplastic cellulose; (2)80 to 20 parts of an aliphatic polyester; (3)0.1 to 10 parts of a reactive monomer; the technical scheme is characterized in that the reactive monomer in the blend is at least grafted to one of thermoplastic cellulose and aliphatic polyester, so that the problem is well solved, the application range of the thermoplastic cellulose blend material is effectively widened, and the blend can be more energy-saving in the processing process of 3D printing wires due to low melt viscosity.

Description

3D printing wire and preparation method thereof

Technical Field

The invention belongs to the field of 3D printing wires, and particularly relates to a graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire with special rheological properties, and a method for preparing the graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire with special rheological properties.

Technical Field

Cellulose is the most abundant organic polymer on earth and also the most renewable biomass material every year. Cellulose is the structural material in the cell wall of green plants, woody plants contain about 30-40% cellulose, and cotton fibers contain about 90% cellulose. The main industrial uses of cellulose are paper and board, with a small amount of cellulose being used for the preparation of regenerated cellulose such as cellulophenol (Cellophane), viscose (Rayon) and some cellulose derivatives.

Since cellulose is a natural polymer that plants convert carbon dioxide and water in the atmosphere into carbon dioxide and water through photosynthesis, carbon elements in cellulose belong to recently fixed carbon and are different from carbon elements fixed millions of years ago in fossil fuels such as petroleum or coal and petrochemical products thereof, and carbon elements fixed at different periods can pass through¹⁴And C isotope calibration method. Due to the differences, the bio-based polymer material prepared based on the biomass raw material has the advantage of low carbon of the raw material compared with the petroleum-based polymer material, and the green low-carbon polymer material can be produced by adopting the production process with low energy consumption and low carbon emission. In view of such considerations, natural polymers including cellulose, hemicellulose, lignin, starch, chitin, and the like, and derivatives and materials thereof have been increasingly focused and researched globally to develop high-quality green, low-carbon, and environmentally-friendly materials. The wide application of the green low-carbon material confirmed by Life Cycle Assessment (Life Cycle Assessment) is helpful for supporting green production and green Life style, and contributes to reducing the content of greenhouse effect gases (carbon dioxide and the like) in the atmosphere and relieving global climate change.

Although cellulose has the advantage of low carbon in raw materials, the amount of cellulose used as a plastic article is small because cellulose does not have thermoplastic properties because its thermal decomposition temperature is lower than its melting point. In order to overcome the defect of cellulose, researchers have developed regenerated cellulose produced by a solution method, i.e. cellulose or a cellulose derivative is dissolved in a solvent, and is processed and formed by the solution to be prepared into a film or is converted into cellulose after spinning, and viscose in the textile industry is prepared by the method.

In addition, the cellulose derivative has a low melting or plasticizing temperature after sufficient chemical transformation of the three hydroxyl groups of each repeated anhydroglucose unit, can be subjected to limited thermoplastic processing to form thermoplastic cellulose, and the materials comprise cellulose ester and cellulose ether with a certain degree of substitution. Because the yield and the product variety of the cellulose derivatives are limited, the viscosity of the industrialized products is higher, and is particularly obvious at lower processing temperature, and the products are not suitable for processing methods needing low melt viscosity, such as spinning, injection molding and the like; cellulose esters and cellulose ethers are currently used in large part as additives in the field of coatings or adhesives [ gayal, manoming, biomass materials and applications, 2008 ].

The 3D printing belongs to an additive technology of a rapid prototyping technology, and is a technology for preparing a 3-dimensional block by printing a material layer by layer on the basis of a digital model file. Through the development of the last 30 years, the 3D technology has been considered as one of the core technologies for changing the laboratory and industrial production modes. The currently used 3D Printing technologies mainly include Stereolithography (Stereolithography), Inkjet Printing (Inkjet Printing), Selective laser sintering (Selective laser sintering), Fused Deposition Modeling (Fused Deposition Modeling), and the like. Materials that can be used for 3D printing include metal powders, ceramic powders, light curable resins, thermoplastics, and the like. [ Analytical Chemistry 2014,86(7),3240-

Cellulose and derivatives thereof have the advantages of wide sources, biodegradability, nontoxicity, chemical and thermal stability and the like, and are receiving more and more attention in the century, and cellulose products prepared by the traditional method show important application in the fields of packaging, medicines, optical films and the like [ Progress in Polymer Science, 2001,26(9), 1605-. In recent years, researchers have begun to combine 3D printing technology with cellulose in an attempt to take advantage of both. For example, Salmora and the like use cellulose acetate particles or starch-cellulose particles as raw materials, and adopt a selective laser sintering technology to prepare a bulk material with good mechanical properties and thermal properties by adjusting laser intensity, scanning speed, particle size of the raw materials and the like [ Polymer Testing, 2009,28(6), 648-. In addition, 3D printing techniques are also used to prepare tablets containing cellulose derivatives and drugs. Such as pierzak et al, mix hydroxypropyl cellulose and Theophylline (Theophylline) of certain composition by twin screw and prepare wire, followed by direct 3D printing of tablets by fused deposition modeling. Compared with the traditional tablet preparation method, the method has the advantages of low cost, accurate dosage control and the like [ http:// dx.doi.org/10.1016/j.jddst.2015.07.016; european Journal of pharmaceuticals and biopharmaceuticals 2015,96, 380-387.

Materials containing cellulose resins prepared by 3D printing techniques also show important applications in artificial bones or other prostheses [ European Journal of pharmaceuticals and biopharmaceuticals 2015,96,380 387-][U.S.Patent 6,932,610B2,U.S.Patent Application,2009/0220917 A1]. A sample containing cellulose resin, inorganic particles and the like is prepared into an artificial bone structure with high precision by a laser sintering technology, and the artificial bone structure can be vividly and vividly used for experimental teaching [ U.S. patent 6,932,610B2 ]]. In addition, cellulose and its derivatives may also play an important role as processing aids such as binders, thickeners, etc. in the preparation of other bulk materials by 3D printing techniques [ U.S. patent 7,332,537B 2, CN 104448744 a,U.S.Patent 2012/003002 A1]. In the preparation of 3D structured blocks of gypsum particles, cellulose and its derivatives can be used as binders to bind gypsum particles into three-dimensional macroscopic materials by means of inkjet printing [ U.S. patent 7,332,537B 2 ]]。

Up to now, there are few reports of blends of thermoplastic cellulose derivatives with biodegradable polyesters for 3D printing materials. Therefore, from the viewpoint of processing applications, there is a technical need to develop a thermoplastic cellulose derivative having a low viscosity and good processability to meet the market demand of the cellulose material in 3D printing.

To date, no document has reported the specific rheological behavior of graft-modified thermoplastic cellulose and aliphatic polyester blends, and no method has been provided in the prior art to effectively reduce the melt viscosity of thermoplastic cellulose and aliphatic polyester blends, limiting the utility of such blends.

The invention discloses a continuous melt extrusion method for effectively reducing the melt viscosity of a blend of thermoplastic cellulose and aliphatic polyester, discovers unexpected phenomena and results, discloses a blend composition with special rheological properties, and successfully applies the blend to the field of 3D printing materials.

Disclosure of Invention

One of the technical problems solved by the invention is that the melt viscosity of the thermoplastic cellulose and aliphatic polyester blend in the prior art is too high to be applied to the field needing low melt viscosity, and provides a graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property, and the 3D printing wire material adopts a blend material to effectively reduce the viscosity of the blend to be lower than the theoretical viscosity of the blend addition of the thermoplastic cellulose and the aliphatic polyester starting material; the blend has the processing performance of preparing the 3D printing wire material at a lower temperature, is superior to the similar blend in the prior art, and can save more energy in the processing process due to the low melt viscosity of the blend.

The second technical problem to be solved by the invention is to provide a method for preparing graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property, and the melt viscosity of the blend obtained by the method is low shear rate (100 s)^-1) At least about 30% lower than the theoretical value of the additive blend of the two starting materials under the conditions; at high shear rate (1363 s)^-1) Under conditions at least 25% lower than the theoretical value of the blended addition of the two starting materials.

In order to solve one of the above technical problems, the technical scheme adopted by the invention is as follows: A3D printing wire contains a graft modified thermoplastic cellulose and aliphatic polyester blend, and the graft modified thermoplastic cellulose and aliphatic polyester blend comprises the following components in parts by mass:

(1)20 to 80 parts of thermoplastic cellulose;

(2)80 to 20 parts of an aliphatic polyester;

(3)0.1 to 10 parts of a reactive monomer;

wherein the reactive monomer in the blend is grafted to at least one of the thermoplastic cellulose and the aliphatic polyester.

In the technical scheme, the 3D printing wire material is prepared from a graft modified thermoplastic cellulose and aliphatic polyester blend, and the graft modified thermoplastic cellulose and aliphatic polyester blend has special rheological properties, such as the melt viscosity of the blend at a low shear rate of 100s^-1Under the condition, the additive ratio is at least 30 percent lower than the blending additive theoretical value of the two main starting materials; at high shear rate 1363s^-1At least 25% lower than the blended addition theoretical starting material of the two main starting materials.

In the technical scheme, the two main starting materials refer to thermoplastic cellulose and aliphatic polyester.

In the above technical solution, the substitution degree of the thermoplastic cellulose is preferably greater than 1.0; more suitable cellulose derivatives have a degree of substitution of more than 1.5, particularly suitable cellulose derivatives have a degree of substitution of more than 2.0.

In the above-mentioned embodiment, the thermoplastic cellulose is preferably cellulose acetate butyrate ester, cellulose acetate valerate ester, cellulose acetate caproate ester, cellulose acetate enanthate ester, cellulose acetate caprylate ester, cellulose acetate pelargonate ester, cellulose acetate caprate ester, cellulose acetate laurate ester, cellulose acetate palmitate ester, cellulose acetate stearate ester, cellulose propionate butyrate ester, cellulose propionate valerate ester, cellulose propionate caproate ester, cellulose propionate enanthate ester, cellulose propionate caprylate ester, cellulose propionate pelargonate ester, cellulose propionate caprate ester, cellulose propionate laurate ester, cellulose propionate stearate ester, or the like.

In the above technical means, the aliphatic polyester is preferably a polyester obtained by condensing α omega-aliphatic diacid or a derivative thereof with aliphatic diol, the α omega-aliphatic diacid is preferably at least two α omega-aliphatic diacids containing 2 to 22 main chain carbon atoms, and includes oxalic acid, 1, 3-malonic acid, succinic acid (1, 4-succinic acid), glutamic acid (1, 5-glutaric acid), adipic acid (1, 6-adipic acid), 1, 7-pimelic acid, 1, 8-suberic acid, 1, 9-azelaic acid, 1, 10-sebacic acid and dibasic acid with carbon atoms up to 22, and the α omega-aliphatic diacid derivative includes anhydride, ester, acyl halide and the like corresponding to the diacids.

In the technical scheme, the α omega-aliphatic diacid is preferably α omega-aliphatic diacid containing substituent groups, further preferably α omega-aliphatic diacid containing 2 to 22 main chain carbon atoms and containing substituent groups, wherein the substituent groups are preferably straight-chain alkyl, alkyl with branched chain, cyclic alkyl, alkyl with an unsaturated structure and dibasic acid with other substituent groups such as cyclohexyl.

In the above technical scheme, the aliphatic diol suitable for preparing the aliphatic polyester of the present invention includes ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 2-pentanediol, 1, 3-pentanediol, 1, 4-pentanediol, 1, 5-pentanediol, 1, 2-hexanediol, 1, 3-hexanediol, 1, 4-hexanediol, 1, 5-hexanediol, 1, 6-hexanediol, 1, 2-heptanediol, 1, 3-heptanediol, 1, 4-heptanediol, 1, 5-heptanediol, 1, 6-heptanediol, 1, 7-heptanediol, 1, 2-octanediol, 1, 3-octanediol, 1, 4-octanediol, 1, 5-octanediol, 1, 6-octanediol, 1, 7-octanediol, 1, 8-octanediol, 1, 2-nonanediol, 1, 3-nonanediol, 1, 4-nonanediol, 1, 5-nonanediol, 1, 6-nonanediol, 1, 7-nonanediol, 1, 8-nonanediol, 1, 9-nonanediol, 1, 2-decanediol, 1, 3-decanediol, 1, 4-decanediol, 1, 5-decanediol, 1, 6-decanediol, 1, 7-decanediol, 1, 8-decanediol, 1, 9-decanediol, 1, 10-decanediol up to a diol having a carbon number of 24 and diols having other substituents such as cyclohexyl.

In the above technical solution, the aliphatic polyester is preferably: at least one of polyethylene oxalate, polyethylene glycol polypropionate, polyethylene succinate, polyethylene glutarate, polyethylene adipate, polyethylene suberate, polypropylene oxalate, polypropylene malonate, polypropylene succinate, polypropylene glutarate, polypropylene adipate, polypropylene suberate, polypropylene sebacate, polybutylene oxalate, polybutylene malonate, polybutylene succinate, polybutylene glutarate, polybutylene adipate, polybutylene suberate, polyhexamethylene oxalate, polypropylene adipate, polyhexamethylene succinate, polyhexamethylene adipate, and polyhexamethylene suberate.

In the above embodiment, the melt index of the blend is at least about 90% higher than the theoretical value of the blend addition of the two main starting materials.

In the above technical scheme, the reactive monomer is at least one of compounds having polar groups such as hydroxyl, carboxyl, carbonyl, ester, amino, mercapto, sulfonic acid, ether bond, halogen, peptide bond, and acid anhydride bond, and further containing unsaturated carbon-carbon double bond. The reactive monomer can react with other components in the blend under certain conditions, and then is grafted to other components through covalent bonds, so that a special modification effect is achieved.

In the above technical solution, the reactive monomer is preferably at least one of maleic anhydride, acrylic acid, methacrylic acid, acrylate, methacrylate, acrylamide, methacrylamide and the like.

In the above technical solution, the blend preferably further comprises: (4)0.01 to 1 part by mass of an initiator.

In the above technical solution, the initiator is a radical initiator, and is an organic compound that can be decomposed under certain conditions to generate radicals, including but not limited to: acyl peroxides, such as Benzoyl Peroxide (BPO); alkyl (dialkyl) peroxides such as di-t-butylperoxide, di-cumylperoxide, cumylperoxide butyl, 3, 5-trimethylcyclohexane-1, 1-diperoxy-t-butyl, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like; peresters such as t-butyl peroxypivalate, t-butyl per-2-ethylhexanoate, t-butyl perbenzoate, peroxydodecanoic acid, etc.; alkyl hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, etc.; ketone peroxides, such as methyl ethyl ketone peroxide; azo compounds, such as Azobisisobutyronitrile (AIBN).

In the above technical solution, the initiator is preferably at least one of benzoyl peroxide, azobisisobutyronitrile, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoic acid peroxide, 2, 5-dimethyl-2, 5-di-tert-butyl peroxy hexane, and the like.

In the above technical solution, the thermoplastic cellulose is preferably cellulose acetate butyrate, the aliphatic polyester is preferably polybutylene succinate, polyethylene succinate, etc., the reactive monomer is preferably hydroxyethyl methacrylate, glycidyl methacrylate, etc., and the initiator is preferably benzoyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide (bis-penta), etc., at this time, the mixture components have good compatibility, and the mixture shows special rheological properties, which can greatly widen the application range of the starting material, and the lower melt viscosity can reduce the energy consumption in the material processing process.

In the above technical solution, the blend material most preferably contains 20 to 80 parts by mass of thermoplastic cellulose, 80 to 20 parts by mass of aliphatic polyester, 0.1 to 10 parts by mass of reactive monomer and 0.01 to 1 part by mass of initiator, at this time, the synergistic interaction between the components is most obvious, and the rheological property and compatibility of the obtained blend are both optimal.

In the above technical solution, the blend material preferably further contains at least one of a compatibilizer, an inorganic filler, an antioxidant, a lubricant, a colorant, and the like.

As described aboveIn the technical scheme, the melt viscosity of the blend 3D printing wire is preferably at a low shear rate (100 s)^-1) Under the conditions of at least 45% lower than the blending addition theoretical value of the two main starting materials (preferably 65 to 20 parts by mass of the aliphatic polyester and 35 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 part by mass of the initiator), and further preferably at least 55% lower (more preferably 50 to 35 parts by mass of the aliphatic polyester and 50 to 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 part by mass of the initiator).

In the technical scheme, the melt viscosity of the blend 3D printing wire is preferably at a high shear rate (1363 s)^-1) Under the conditions of at least 35% lower than the blending addition theoretical value of the two main starting materials (preferably 65 to 20 parts by mass of the aliphatic polyester and 35 to 80 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 8 parts by mass, and the initiator is 0.05 to 0.2 parts by mass), further preferably at least 45% lower (more preferably 50 to 20 parts by mass of the aliphatic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 6 parts by mass, and the initiator is 0.075 to 0.15 parts by mass).

In the above technical solution, the melt index of the blend 3D printing wire is preferably at least about 90% higher, more preferably at least about 150% higher (preferably 65 to 20 parts by mass of aliphatic polyester and 35 to 80 parts by mass of thermoplastic cellulose, with 2 to 8 parts by mass of reactive monomer and 0.05 to 0.2 parts by mass of initiator), and more preferably at least about 200% higher (more preferably 50 to 20 parts by mass of aliphatic polyester and 50 to 80 parts by mass of thermoplastic cellulose, with 2 to 6 parts by mass of reactive monomer and 0.075 to 0.15 parts by mass of initiator) than the blending addition theoretical value of the two main starting materials.

The aliphatic polyester of the present invention can be produced by polymerizing the above-mentioned various aliphatic diacids with an aliphatic diol. The catalyst for polymerization includes compounds containing metallic tin, antimony, titanium, etc. The aliphatic polyester includes chain-extended aliphatic polyesters, and various compounds or polymers having reactivity with carboxyl or hydroxyl groups can be used as the chain extender, for example, the chain extender includes a chain extender containing two or moreFunctional isocyanates such as hexamethylene diisocyanate (HMDI). Suitable chain extenders include compounds containing multiple epoxy functional groups, such as those produced by BASF

ADR-4368C,

ADR-4368CS and the like. The chain extender of the present invention is present in an amount of from 0.2 to 4% by mass, and in some embodiments from 0.5 to 3% by mass.

The aliphatic polyesters in the present invention include linear and branched polyesters. The synthesis of branched polyesters one or more branching agents are added during the synthesis. The branching agent is generally a polybasic acid having two or more carboxyl groups, a polyhydric alcohol or a polyhydroxy acid having two or more hydroxyl groups, or the like. Suitable branching agents include glycerol, trimethylolethane, trimethylolpropane, 1,2, 4-butanetriol, pentaerythritol, 1,2, 6-hexanetriol, sorbitol, 1,2, 3-benzenetricarboxylic acid (hemimellitic acid), 1,2, 4-benzenetricarboxylic acid (trimelitic acid), 1,3, 5-benzenetricarboxylic acid (trimesic acid), anhydrides, and the like.

In order to solve the second technical problem, the technical scheme adopted by the invention is as follows: a method for preparing the 3D printing wire material adopts continuous melt blending extrusion, the components with required amount are uniformly mixed in a molten state, and are extruded and granulated to obtain grafting modified thermoplastic cellulose and aliphatic polyester blend particles with special rheological property; and melting and extruding the blend particles in an extruding device, and preparing the 3D printing wire through a die.

In the above technical solution, the required amounts of the respective components include the required amount of the thermoplastic cellulose, the required amount of the aliphatic polyester, the required amount of the reactive monomer, and further preferably the required amount of the initiator.

In the above technical solution, the melt blending method of the graft modified thermoplastic cellulose and aliphatic polyester blend is preferably a twin-screw continuous extrusion method.

In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and aliphatic polyester blend preferably comprises the steps of continuously extruding and granulating the thermoplastic cellulose powder, blending the thermoplastic cellulose powder with the aliphatic polyester, the reactive monomer and the initiator according to a required ratio, and then adding the mixture into a double-screw extruder for extrusion and granulation.

In the above technical solution, the melt blending method of the graft modified thermoplastic cellulose and aliphatic polyester blend preferably includes continuously extruding and granulating the thermoplastic cellulose powder, and then adding the thermoplastic cellulose powder, the aliphatic polyester, the reactive monomer and the initiator into a twin-screw extruder according to the required feeding ratio for extrusion and granulation.

In the above technical scheme, the melt blending method of the graft modified thermoplastic cellulose and aliphatic polyester blend preferably comprises the steps of respectively metering the thermoplastic cellulose powder, the aliphatic polyester, the reactive monomer and the initiator according to a certain feeding proportion, and extruding and granulating the mixture in a twin-screw extruder.

In the above technical solution, the screw rotation speed of the melt blending method of the graft-modified thermoplastic cellulose and aliphatic polyester blend is preferably 50rpm to 1500rpm.

In the above technical solution, the temperature of the melt blending method of the graft-modified thermoplastic cellulose and aliphatic polyester blend is preferably 140 ℃ to 240 ℃.

In the above technical scheme, the die is a circular die.

The materials and preparation methods used in the present invention are briefly described below:

1. thermoplastic cellulose

The thermoplastic cellulose is a cellulose derivative with a wide range, and the three hydroxyl groups on each repeated anhydroglucose unit of the cellulose derivative are partially or completely chemically modified in the forms of esterification, etherification, etc. The parameter characterizing its Degree of modification is the Degree of Substitution (Degree of Substitution), which is defined as the average number of substitutions in the three hydroxyl groups per repeating anhydroglucose unit, with a maximum of 3.0(3 hydroxyl groups are completely substituted) and a minimum of 0 (pure cellulose).

The thermoplastic cellulose ester included in the present invention includes a mixed cellulose ester of cellulose and two or more kinds of organic aliphatic carboxylic acid, organic aliphatic acid anhydride and organic aliphatic acid halide, and the difference in the number of carbon atoms between different organic aliphatic carboxylic acid, organic aliphatic acid anhydride and organic aliphatic acid halide is 1 or more.

Cellulose esters are typically made by reacting natural cellulose with an organic acid, anhydride or acid chloride, etc., with a degree of substitution of the hydroxyl groups in the cellulose of from 0.5 to 2.8. Suitable cellulose ester products include Eastman, produced by Eastman chemical company, USA^TMCellulose acetate butyrate CAB-171-15, CAB-321-0.1, CAB-381-0.1, CAB-381-0.5, CAB-381-20, CAB-485-10, CAB-500-5, CAB-531-1 and the like. For example: CAB-531-1 contains butyryl component 50 wt%, acetyl component 2.8 wt%, and hydroxyl component 1.7 wt%, and has a viscosity of 5.6 poise measured according to ASTM 1343. Cellulose ester is used in fiber, textile, paint, food additive, pharmaceutical industry and other industries. In the coating industry, the addition of cellulose esters can improve the coating effect, including: hardness, flow, flatness, transparency, gloss, and the like. Cellulose Acetate Propionate (CAP) and Cellulose Acetate Butyrate (CAB) are two types of mixed cellulose esters that have a wide range of commercial uses.

2. Aliphatic polyester

The aliphatic polyester is a biodegradable plastic and is prepared by condensation polymerization of aliphatic diacid or aliphatic diacid anhydride, aliphatic diacid halide, aliphatic diacid ester and aliphatic diol.

3. Reactive monomer

The reactive monomer in the present invention is a vinyl compound having a polar group including, but not limited to: hydroxyl, carboxyl, carbonyl, ester, amino, mercapto, sulfonic acid, ether bond, halogen, peptide bond, acid anhydride bond, etc. The reactive monomer can react with other components in the blend under certain conditions, and then is grafted to other components through covalent bonds, so that a special modification effect is achieved.

The reactive monomer in the present invention is preferably at least one of maleic anhydride, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, acrylamide, methacrylamide and the like. More preferred reactive monomers are methacrylates, such as at least one of hydroxyethyl methacrylate (HEMA), Glycidyl Methacrylate (GMA), and the like.

4. Initiator

The initiator described in the present invention is a free radical initiator which under certain conditions can decompose an organic compound which generates free radicals, including but not limited to: acyl peroxides, such as Benzoyl Peroxide (BPO); alkyl (dialkyl) peroxides such as di-t-butylperoxide, di-cumylperoxide, cumylperoxide butyl, 3, 5-trimethylcyclohexane-1, 1-diperoxy-t-butyl, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like; peresters such as t-butyl peroxypivalate, t-butyl per-2-ethylhexanoate, t-butyl perbenzoate, peroxydodecanoic acid, etc.; alkyl hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, etc.; ketone peroxides, such as methyl ethyl ketone peroxide; azo compounds, such as Azobisisobutyronitrile (AIBN).

The initiator suitable for use in the present invention is preferably at least one of benzoyl peroxide, azobisisobutyronitrile, dicumyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, benzoic acid peroxide, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, and the like. More preferred initiators are at least one of benzoyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butylperoxyhexane.

5. Graft-modified thermoplastic cellulose and biodegradable aliphatic polyester blends

The blend comprises 20 to 80 parts by mass of thermoplastic cellulose, 80 to 20 parts by mass of aliphatic polyester, 0.1 to 10 parts by mass of reactive monomer and 0.01 to 1 part by mass of initiator. The blend comprises, in addition to the above components, at least one additive selected from the group consisting of: compatibility agents, inorganic fillers, antioxidants, lubricants, colorants, and the like.

The physical and chemical properties (such as melt viscosity, melt index, etc.) of the polymer blend are mainly determined by the types and composition ratios of the polymers constituting the polymer blend. The polymer type mainly determines the compatibility between the components of the blend, which is a measure of the interaction between different polymers, and when the interaction between different polymers is strong, it can be stably and uniformly mixed on a molecular scale, it is called a miscible (mismixing) system; the interaction between other polymers is weak, and the polymers can be stably and uniformly dispersed in a nano scale or a micron scale although the polymers cannot be mutually dissolved in a molecular scale, so that the blend is called a compatible system; other polymers have weak interactions and even if they are mixed by force, they tend to form separate phase regions, and such blends are incompatible systems. Incompatible systems have distinct phase separation of the different components, i.e.form a phase separated system. Polymer blend glass transition temperature (' T_g") information can be used as a simple judgment basis for the compatibility among the components [ multicomponent polymer-principle, structure and performance, King's institute and editions, 2013, p.20-22 ], if the blend respectively keeps the glass transition temperature of the raw material components, the compatibility among the components is not good, and if the blend only has one glass transition temperature, the compatibility among the components is better. Under the condition of determined polymer types, a certain functional relationship exists between some physical and chemical properties (such as melt viscosity, melt index and the like) of the blend and the composition ratio thereof [ handbook of plastics engineering handbook, Huangrui kingdom, 2000, p.633-637; melt Rheology of Polymer Blends from Melt Flow Index, International Journal of polymeric Materials,1984,10, p.213-235, one can generally infer and even design Blends with specific properties. In some poorly compatible blend systems, it may occur that the viscosity of the blend is lower than that of the raw material groupThe reasons for this phenomenon are not yet definitively known in the chapter [ fourth statistical mechanics, golden sun, 1998, p.630-633 ], one of which is explained by the fact that interfacial slippage between the different phases leads to a decrease in the overall viscosity after mixing. Similar phenomena have not been reported in a blend system with good compatibility, and if the phenomena can be applied in a system with good compatibility, the phenomena have great potential.

The blend composition disclosed by the invention also contains reactive monomers and initiators which are good in compatibility with main components of the blend, such as hydroxyethyl methacrylate, glycidyl methacrylate and the like, the reactive monomers are different from common plasticizers and have high reactivity, free radical reaction is easy to occur in a twin-screw extruder under the conditions of high shear rate, high melt temperature (above 200 ℃) and the existence of the initiators, theoretically, the reactive monomers can be grafted on any C-H bond in the blend components (FIGS. 1 and 2 are two possible structural schematic diagrams generated in the invention), the effect of the reactive monomers is obviously different from that of the plasticizers, and after reactive extrusion, unreacted monomers can be removed in a devolatilization process, so that the situation that the viscosity reduction of a mixed system is not established by simply regarding the reactive monomers as the plasticizers. The initiator is not only added in a small amount, but also easily decomposed at high temperature to generate free radicals to be consumed. After reactive grafting, the interaction between the thermoplastic cellulose and the biodegradable polyester will be stronger due to the presence of the grafting monomer compared to a blend of the same composition without grafting. In conclusion, the special rheological property of the graft modified thermoplastic cellulose and aliphatic polyester blend disclosed by the invention is caused by the special interaction among the components, the compatibility among the components of the mixed system is good, and the phenomenon of viscosity reduction after mixing is less in the compatible mixed system, and related reports are rarely found in literature data.

There are a number of ways in which the properties of the blend can be described, the rule of addition being one of the simplest. The theoretical properties of some polymer blends can be generally presumed by the rule of addition, which can be expressed by the following formula (only the major components are considered here, neglecting the components below 2%):

P＝c₁P₁+c₂P₂

p is a property of the blend, c₁And P₁Is the concentration and nature of component 1; c. C₂And P₂Is the concentration and nature of component 2. The properties (P) of the blend of the thermoplastic cellulose and the aliphatic polyester according to the present invention, such as the melt apparent viscosity, the melt index, etc., can be calculated by using the addition rule to calculate theoretically predicted values, i.e., defined as "addition theoretical values", which can be compared with experimentally detected values of apparent viscosity, melt index, etc. The concentration of the components can be expressed by mass fraction or volume fraction, and the mass fraction is selected to calculate a theoretical value in the invention.

A blend composition of one embodiment of the present invention comprises 20 to 80 parts by mass of a thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of an aliphatic polyester such as polybutylene glycol diacetate or polybutylene succinate, 0.1 to 10 parts by mass of a reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate, and 0.01 to 1 part by mass of an initiator such as benzoyl peroxide or bis-penta initiator, and is characterized in that the melt viscosity of the blend is at a low shear rate (100 s)^-1) Under conditions at least 30% lower than the theoretical value of the mixed addition of the two main starting materials. The melt viscosity of some more preferred compositions of the blends is at low shear rate (100 s)^-1) Under conditions at least 45% lower than the theoretical value of the mixed addition of the two main starting materials; some of the most preferred compositions of the blends have melt viscosities at low shear rates (100 s)^-1) Under conditions at least 55% lower than the theoretical value of the mixed addition of the two main starting materials.

A blend composition of one embodiment of the present invention comprises 20 to 80 parts by mass of a thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of an aliphatic polyester such as polybutylene glycol diacetate or polybutylene succinate, 0.1 to 10 parts by mass of a reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate, and 0.01 to 1 part by mass of an initiator such as benzoyl peroxide or bis-penta initiator, and is characterized in that the melt viscosity of the blend is at a high shear rate (1363 s)^-1) Mixing of two main starting materials under conditionsThe addition theory is at least 25% lower. The melt viscosity of some more preferred compositions of the blends is at high shear rate (1363 s)^-1) Under conditions at least 40% lower than the theoretical value of the mixed addition of the two main starting materials; the melt viscosity of some of the most preferred compositions of the blends is at high shear rate (1363 s)^-1) Under conditions at least 50% lower than the theoretical value of the mixed addition of the two main starting materials.

The blend composition of one embodiment of the invention comprises 20 to 80 parts by mass of thermoplastic cellulose acetate butyrate ester, 80 to 20 parts by mass of aliphatic polyester such as polybutylene glycol diacetate or polybutylene succinate, 0.1 to 10 parts by mass of reactive monomer such as hydroxyethyl methacrylate or glycidyl methacrylate and 0.01 to 1 part by mass of initiator such as benzoyl peroxide or dipenta-penta-bis, and is characterized in that the melt index of the blend is at least about 90% higher than the theoretical value of the mixed addition of the two main starting materials. Some more preferred compositions have a melt index at least 200% higher than the theoretical value of the mixed addition of the two main starting materials; some of the most preferred compositions have a melt index at least 250% higher than the theoretical value of the mixed addition of the two main starting materials.

The blends of the present invention, which are composed in certain proportions, have "unusually", "unexpectedly" ratios of the main starting materials: the lower theoretical value of the additive mixing of pure thermoplastic cellulose and aliphatic polyester starting materials, i.e., the "concave" curve in the "apparent viscosity-composition" diagram, is reflected by the phenomenon of "Melt viscosity trap" (Melt viscositiwell), indicating that the blend has an "Anti-Synergistic Effect" of apparent viscosity (either Effect or Anti-synthetic Effect).

The blends of the present invention, which are composed in certain proportions, have "unusually", "unexpectedly" ratios of the main starting materials: the melt index (MFR: Meltflow Rate) of pure thermoplastic cellulose and aliphatic polyester starting materials is higher than the theoretical value of the mixed addition, i.e. in a "melt index-composition" relationship diagram, a "convex" curve is presented, which is represented by a "melt index peak" (MFRPeak) phenomenon, and the blend is shown to have a "Synergistic Effect" (Synergistic Effect) of the melt index.

6. Method for preparing graft modified thermoplastic cellulose and biodegradable aliphatic polyester blend

The invention relates to a method for preparing a grafted modified thermoplastic cellulose and aliphatic polyester blend. The process comprises homogeneously mixing in a continuous process the desired amount of thermoplastic cellulose, the desired amount of aliphatic polyester, the desired amount of reactive monomer and the desired amount of initiator in the molten state and extrusion granulating the mixture, the blend being characterized by a melt viscosity at low shear rate (100 s)^-1) Under the condition, the additive ratio is at least 30 percent lower than the blending additive theoretical value of the two main starting materials; at high shear rate (1363 s)^-1) At conditions at least 25% lower than the theoretical value for the blended addition of the two primary starting materials, and the melt index of the blend is at least about 90% higher than the theoretical value for the blended addition of the two primary starting materials.

The continuous melting preparation method comprises a two-step method and a one-step method. In the two-step method, thermoplastic cellulose powder is firstly granulated by a single-screw or double-screw extruder, then thermoplastic cellulose particles, aliphatic polyester particles, reactive monomers and an initiator are uniformly mixed according to a certain proportion, and then the mixture is added into a feeding port of the double-screw extruder by a feeding machine according to a certain feeding rate. The feeder can be a weight loss feeder or a volume feeder. The other embodiment is that a plurality of feeders are adopted to respectively meter the thermoplastic cellulose particles, the aliphatic polyester particles, the reactive monomer and the initiator into a double-screw extruder according to a certain feeding proportion for reaction extrusion granulation.

The one-step method of the invention is that the thermoplastic cellulose powder is directly added into the feeding port of the double-screw extruder by a feeder according to a certain feeding rate without being processed and granulated by heat, meanwhile, the aliphatic polyester particles, the reactive monomer and the initiator are added into the feeding port of the double-screw extruder by other feeders according to a certain feeding rate, and then the mixture particles are prepared by extruding the aliphatic polyester particles, the reactive monomer and the initiator by double screws and cutting the extruded sample strips into particles by a water tank or underwater. The extrudate can also be air cooled by an anhydrous process and then pelletized.

The extrusion temperature suitable for the present invention is preferably 140 ℃ to a temperature at which the thermal decomposition temperature of the thermoplastic cellulose and the aliphatic polyester is low, and more preferably 140 ℃ to 240 ℃. The rotation speed of the extruder is preferably 50rpm to 1500rpm, more preferably 100rpm to 800 rpm.

Melt blending devices suitable for use in the present invention include a variety of mixers, Farrel continuous mixers, Banbury mixers, single screw extruders, twin screw extruders, multiple screw extruders (more than two screws), reciprocating single screw extruders such as Buss Ko-kneaders (Buss Ko-kneaders), and the like. Preferred processes are continuous melt blending extrusion processes including twin screw extrusion processes. Continuous twin-screw extruders suitable for use in the present invention include twin-screw extruders of different designs, such as the ZSK Mcc18 co-rotating parallel twin-screw extruder manufactured by Coperion, Germany, and the like.

The invention demonstrates that the graft-modified thermoplastic cellulose prepared by the twin-screw continuous melt coextrusion process has an "unexpected" low melt viscosity when blended with aliphatic polyesters. One embodiment of the invention is that under the same conditions, the melt viscosity of the blend is lower than the theoretical value of the mixed addition of the starting materials of the thermoplastic cellulose and the aliphatic polyester. This viscosity reduction is prevalent, including at lower shear rates such as 100s^-1And at higher shear rates, e.g. 1363s^-1. At 100s^-1The melt viscosity of the blend is at least 30% lower than the theoretical value of the mixed addition of the two main starting materials at shear rate. Some more preferred compositions (65 to 20 parts by mass of aliphatic polyester and 35 to 80 parts by mass of thermoplastic cellulose, 2 to 8 parts by mass of reactive monomer, 0.05 to 0.2 parts by mass of initiator) have a melt viscosity at least 45% lower than the theoretical value of the mixed addition of the two main starting materials, and some most preferred compositions (50 to 35 parts by mass of aliphatic polyester and 50 to 65 parts by mass of thermoplastic cellulose, 2 to 6 parts by mass of reactive monomer, 0.075 to 0.15 parts by mass of initiator) have a melt viscosity at least 55% lower than the theoretical value of the mixed addition of the two main starting materials. At 1363s^-1Of blends at shear rateThe melt viscosity is at least 25% lower than the theoretical value of the mixed addition of the two main starting materials, the melt viscosity of a blend of some more preferred compositions (preferably 65 to 20 parts by mass of the aliphatic polyester and 35 to 80 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 8 parts by mass, and the initiator is 0.05 to 0.2 parts by mass) is at least 35% lower than the theoretical value of the mixed addition of the two main starting materials, and the melt viscosity of a blend of some most preferred compositions (50 to 20 parts by mass of the aliphatic polyester and 50 to 80 parts by mass of the thermoplastic cellulose, the reactive monomer is 2 to 6 parts by mass, and the initiator is 0.075 to 0.15 parts by mass) is at least 45% lower than the theoretical value of the mixed addition of the two main starting materials.

One concrete embodiment of the graft modified thermoplastic cellulose and aliphatic polyester blend material prepared by the invention is that the melt index of the blend is higher than the mixed addition theoretical value of two main starting materials. The blend of the preferred composition has a melt index at least about 90% higher than the theoretical value of the mixed addition of the two main starting materials, more preferably the blend of the composition (65 to 20 parts by mass of the aliphatic polyester and 35 to 80 parts by mass of the thermoplastic cellulose, 2 to 8 parts by mass of the reactive monomer, and 0.05 to 0.2 parts by mass of the initiator) has a melt index at least 200% higher than the theoretical value of the mixed addition of the two main starting materials, and most preferably the blend of the composition (50 to 35 parts by mass of the aliphatic polyester and 50 to 65 parts by mass of the thermoplastic cellulose, 2 to 6 parts by mass of the reactive monomer, and 0.075 to 0.15 parts by mass of the initiator) may have a melt index body at least 250% higher than the theoretical value of the mixed addition of the two main starting materials.

7. Method for preparing graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire

The invention discloses a method for preparing a 3D printing wire material of a graft modified thermoplastic cellulose and aliphatic polyester blend with special rheological properties, which is characterized in that the blend consists of 20 to 80 parts by mass of thermoplastic cellulose, 80 to 20 parts by mass of aliphatic polyester, 0.1 to 10 parts by mass of reactive monomer and 0.01 to 1 part by mass of initiator. The blend was prepared by the continuous melt extrusion blending process described above. The melt viscosity of the blend isLow shear rate (100 s)^-1) Under the condition, the addition theoretical value is at least 30 percent lower than that of the two main raw materials; at high shear rate (1363 s)^-1) Under conditions at least 25% lower than the theoretical value of the addition of the two main raw materials.

The invention discloses a method for preparing a graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property, preferably a single-screw extrusion wire forming method. In the method, blend particles prepared in advance and some auxiliaries are added into a single-screw extruder, the single-screw extruder is generally divided into three stages on the effective length, the first stage is a conveying section, and the blend is preheated and extruded at the first stage; the second section is a compression section, the depth of the thread groove is reduced from large to small, the melt temperature reaches the degree of plasticizing and melting the blend, and the section can also comprise a thread section for increasing the mixing effect; the third section is a metering section, and the blend melt is conveyed to a 3D printing wire mold according to a certain melt flow under the rotation of a screw rod. The die is provided with one or more circular small holes, and the circular holes can be selected to have different diameters according to the requirements of the printer, and the diameter is generally 1.75 millimeters (mm) or 3.00 millimeters (mm). And cooling the extruded printing wire material, and rolling after detection. There are various methods of cooling, including water cooling or air cooling.

The invention discloses a method for preparing a graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property, and a double-screw extrusion wire forming method can be selected. In the method, pre-prepared blend particles and some auxiliary agents are plasticized, melted and mixed in a double-screw extruder, and then extruded out of a die, wherein the die is provided with one or more round small holes, different diameters can be selected according to the requirements of a printer, the diameter of the round holes is generally 1.75 millimeters (mm) or 3.00 millimeters (mm), the diameter of the silk is monitored on line through water cooling or air cooling, and the diameter of the silk is controlled within a required range through adjusting the winding speed. The extrusion temperature of the twin-screw extruder is preferably 140 ℃ to 240 ℃ and the extruder rotation speed is preferably 50rpm to 1500rpm, more preferably 100rpm to 800 rpm.

The invention discloses a method for preparing a graft modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property, and a melt extrusion method can be selected. In this method, pellets of a blend prepared in advance are simply melted and then extruded from a die, and the diameter of the extruded filament is controlled to be about 1.75 millimeters (mm) or 3.00 millimeters (mm).

The 3D printing wire prepared by the method can be used for preparing 3D printing products by Fused Deposition Modeling (FDM).

The grafting modified thermoplastic cellulose and aliphatic polyester blend 3D printing wire material with special rheological property prepared by the continuous extrusion blending method disclosed by the invention has lower melt viscosity and higher melt index than the mixing addition theoretical value of two main starting raw materials, has better toughness and strength, has better 3D printing performance than the raw materials, has wide application potential and obtains better technical effect.

Drawings

FIG. 1 is a schematic diagram of the structure of a possible HEMA graft-modified PBS (PBS-g-HEMA)

FIG. 2 is a schematic diagram showing the structure of a possible HEMA graft-modified CAB (CAB-g-HEMA)

FIG. 3180 ℃ is a graph showing the relationship between the apparent shear viscosity and shear rate of each compounded particle.

FIG. 4180 ℃ for 100s for each of the compounded particles^-1The dashed line in the figure is the line of the theoretical calculated values for the addition of PBS to CAB.

FIG. 5180 deg.C, each compounded particle is 1363s^-1The dashed line in the figure is the line of the theoretical calculated values for the addition of PBS to CAB.

FIG. 6 DSC cooling curves of the respective compounded particles.

FIG. 7 DSC second temperature rise profile for each compounded particle.

FIG. 8 is a graph showing the relationship between the glass transition temperature and the composition of each compounded particle.

Fig. 9 TGA profile of each compounded particle under air atmosphere.

FIG. 10 is a graph showing the relationship between the melt index (190 ℃,2.16kg) and the composition of each compounded particle, wherein the dotted line is a line representing the theoretical calculated value of the addition of PBS and CAB.

The invention carries out performance measurement according to the following method:

melt index (MFR) determination method: according to ISO 1133 standard, the melt index meter is adopted to measure, the cylinder temperature is 190 ℃, the weight load is 2.16kg, the diameter of a die is 2.095mm, the length is 8mm, the preheating time is 4min, samples are automatically cut at set time intervals, 5 times of averaging is carried out, and the measurement result is expressed by grams per 10 minutes (g/10 min).

Rheological behavior determination method: measured by a Malvern Instruments Rosand RH7 hot high pressure capillary rheometer with the processing software of Lannch

Version 8.60. The test uses a sensor with 10000Psi pressure and a 16/1.0/180 round hole type capillary die. For batch loading compaction at the time of loading, two 0.5MPa preloads and 2 minute preheats were performed prior to testing to ensure complete melting and compaction of the particles at the selected temperature (180 ℃). The test was chosen to determine the apparent shear viscosity at the following shear rates: 100,192,369,709,1363,2615, and 5019s^-1。

Thermogravimetric analysis (TGA): the testing was performed on a Discovery series thermogravimetric analyzer from TA Instruments with the processing software TA Instruments Trios version 3.1.4. The temperature of the isobalance chamber was required to be stabilized at 40 ℃ before testing. During testing, 5-10 mg of sample is weighed and placed in a ceramic crucible, and the test is carried out in the air atmosphere with the flow rate of 20mL/min, the temperature rise range is 30-600 ℃, and the temperature rise rate is 10 ℃/min.

Thermal performance analysis (DSC): the tests were performed on a Discovery series Differential Scanning Calorimeter (DSC) manufactured by TA Instruments, Inc., with the processing software TA Instruments Trios version 3.1.5, equipped with a TARefrigerated cooking System 90 mechanical refrigeration accessory. The testing atmosphere is 50mL/min of nitrogen, and the amount of the sample required by the test is 5-10 mg. The test procedure was as follows: firstly, the temperature is stabilized at 40 ℃,heating to 250 deg.C at 10 deg.C/min, keeping the temperature for 2min to remove heat history, cooling to-70 deg.C at 10 deg.C/min, and heating to 250 deg.C at 10 deg.C. And recording the temperature reduction process and the second temperature rise process to research the thermal performance of the sample. By DSC measurement, software can be used to directly derive the crystallization temperature ("T") of a sample_c"), melting temperature (" T ")_m"), glass transition (" T ")_g"), enthalpy change (" △ H "), etc.

Detailed Description

The present invention is specifically described by the following examples. It should be noted that the following examples are given solely for the purpose of illustration and are not to be construed as limitations on the scope of the invention, as many insubstantial modifications and variations of the invention may be made by those skilled in the art in light of the above teachings.

Comparative example 1

The polybutylene succinate (PBS) used in the invention is produced by Showa Denko K.K., and is of the brand

And MD 1001. Raw materials

MD 1001PBS pellets were extruded and pelletized using a PolyLabHAAKE Rheomex OS PTW16 co-rotating twin-screw extruder (screw diameter 16mm, L/D40) from Thermo Fisher scientific Co., U.S.A.) as comparative examples. The extruder has a total of 11 sections from the feed port to the die, numbered 1-11, wherein section 1 serves only as a feed and is not heated. A volume type particle feeder attached to the extruder and used for feeding the particles after calibration

The MD 1001 PBSA raw material was fed into the twin screw at a feed rate of 2000 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 204 ℃, and the torque is 50-56%. The extruder was fitted with a circular port of 3mm diameterThe sample strip is extruded from a die, cooled in water bath, and cut into cylindrical particles of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 4.5g/10 min.

Comparative example 2

Cellulose Acetate Butyrate (CAB) used in the present invention was produced by Eastman, USA^TMCompany, brand Eastman^TMCAB-531-1. Raw material Eastman^TMCAB-531-1 powder was pelletized by extrusion using a PolyLab HAAKE Rheomex OS PTW16 co-rotating twin-screw extruder (screw diameter 16mm, L/D. 40) of Thermo Fisher scientific Co., U.S.A.As a comparative example. The extruder has a total of 11 sections from the feed port to the die, numbered 1-11, wherein section 1 serves only as a feed and is not heated. The attached volumetric powder feeder of the extruder is used for Eastman after being calibrated^TMFeeding CAB-531-1 raw material into twin screw at a feeding speed of 1500 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 205 ℃, and the torque is 58-61.5%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 6.1g/10 min.

[ example 1 ]

The grafting monomer hydroxyethyl methacrylate (HEMA) used in the invention is an analytical pure product of Tokyo chemical industry Co., Ltd (TCI), and the dosage of the grafting monomer hydroxyethyl methacrylate (HEMA) is 2% of the total mass of PBS and CAB. The initiator 2, 5-dimethyl-2, 5-di-tert-butyl hexane peroxide (bis-dipenta) used in the invention is an analytically pure product of carbofuran technologies ltd, and the dosage of the initiator is 5 percent of the dosage of HEMA, namely 1 per mill of the total mass of PBS and CAB. Will be provided with

MD 1001PBS and Eastman^TMCAB-531-1 at a mass ratio of 4:1, and addingAmounts of HEMA and Bidawu were thoroughly mixed and extruded to pelletize in a PolyLab HAAKE Rheomex OSTW 16 co-rotating twin screw extruder as mentioned above. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 2000 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 208 ℃, and the torque is 35.5-40%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 9.4g/10 min. According to the above feeding and processing conditions, besides some side reactions, HEMA graft modified PBS (fig. 1 is a schematic diagram of a possible PBS-g-HEMA structure) and/or HEMA graft modified CAB structure (fig. 2 is a schematic diagram of a possible CAB-g-HEMA structure) can be generated in the system, and the compatibility and interaction between the components can be enhanced while the molecular weight of the components is increased to some extent.

[ example 2 ]

Will be provided with

MD 1001PBS and Eastman^TMCAB-531-1 was prepared by melt blending and extruding pellets in a polyLab HAAKE Rheomex OS PTW16 co-rotating twin screw extruder, as mentioned above, with the addition of the desired amounts of HEMA and bis-di-penta in a mass ratio of 13:7, and thoroughly stirred. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1500 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 201 ℃, and the torque is 33-38.5%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, and vacuum drying at 60 deg.CPackaging for use after 4 hr. The melt index of the particles at 190 ℃ under 2.16kg was 13.9g/10 min.

[ example 3 ]

Will be provided with

MD 1001PBS and Eastman^TMCAB-531-1 was mixed with the required amount of HEMA and bis-di-penta in a mass ratio of 1:1, stirred well, and pelletized by melt blending and extrusion in a co-rotating twin screw extruder of PolyLab HAAKE Rheomex OS PTW16 mentioned above. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1500 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 204 ℃, and the torque is 31-37%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 18.8g/10 min.

[ example 4 ]

Will be provided with

MD 1001PBS and Eastman^TMCAB-531-1 was prepared by melt blending and extruding pellets in a 7:13 weight ratio in a co-rotating twin screw extruder of PolyLab HAAKE Rheomex OS PTW16 with the addition of the desired amounts of HEMA and dipentane, followed by thorough mixing. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1500 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 202 ℃, and the torque is 31-36%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting granuleAnd vacuumizing in a vacuum drying oven at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 20.8g/10 min.

[ example 5 ]

Will be provided with

MD 1001PBS and Eastman^TMCAB-531-1 was mixed with the required amount of HEMA and bis-di-penta in a mass ratio of 1:4, stirred well, and pelletized by melt blending and extrusion in a co-rotating twin screw extruder of PolyLab HAAKE Rheomex OS PTW16 mentioned above. In section 1 of the extruder, a calibrated volumetric particle feeder was used to feed the mixed particles at the following speeds: 1500 g/hr. The temperatures of 2-11 sections of the extruder are respectively as follows: 160 ℃,170 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃,180 ℃ and 180 ℃, the screw rotation speed is set at 200rpm, after stabilization, the melt temperature is about 201.5 ℃, and the torque is 32-38.5%. The extruder is provided with a circular neck ring die with the diameter of 3mm, and a sample strip is extruded from the neck ring die, cooled in water bath and cut into cylindrical particles with the diameter of about 3mm by a granulator. Collecting particles, vacuum drying at 60 deg.C for 4hr, and packaging. The melt index of the particles at 190 ℃ under 2.16kg was 18.1g/10 min.

[ example 6 ]

All 7 of the above particles, including comparative examples 1-2 and examples 1-5, were subjected to rheological behavior measurements on a Malvern instruments and RH7 hot high pressure capillary rheometer, the test method being as described above. The apparent shear viscosity of each particle at 180 ℃ is related to the shear rate in FIG. 3. Wherein the shear rate is 100s^-1And 1363s^-1The apparent shear viscosity versus composition is shown in FIGS. 4 and 5, respectively, with specific values listed in tables 1 and 2.

From FIG. 3, it can be seen that the shear thinning phenomenon, i.e., the shear viscosity decreases with increasing shear rate, is very common in polymer systems, indicating that the basic properties of the system do not change significantly after blending. The apparent shear viscosity of the mixture is all under the same conditions

MD 1001PBS and Eastman^TMBelow CAB-531-1, the viscosity of the system is obviously reduced after mixing. Referring specifically to fig. 4 and 5, it can be seen that the apparent shear viscosity of the particles after blending is lower than that of either of the pure starting materials, and the viscosity curve is "concave," i.e., an unexpected "viscosity trap," which indicates that the particles after blending exhibit a decrease in viscosity at both high and low shear rates.

Hydroxyethyl methacrylate (HEMA) added as a small molecule to the whole can be regarded as a plasticizer which can reduce the whole viscosity, but HEMA has higher reactivity than the common plasticizer, and free radical reaction is very easy to occur in a twin-screw extruder under the conditions of high shear rate, high melt temperature (above 200 ℃) and double-five initiator, theoretically, reactive monomers can be grafted on any C-H bond in the blend components (FIG. 1 and FIG. 2 are two possible structural diagrams generated in the invention), and obviously HEMA is simply regarded as the plasticizer to explain that the viscosity of the mixed system is reduced and is not satisfied. The adding amount of the diindipentan is small, and the diindipentan is easy to decompose at high temperature to generate free radicals to be consumed, and plays a role in preventing the reduction of the molecular weight of the raw materials in the processing process, so the adding amount of the diindipentan is not a reason for the reduction of the viscosity of the mixed system. In conclusion, the viscosity reduction of the mixed system is caused by special interaction among the components, the compatibility among the components of the mixed system is good, and the phenomenon of viscosity reduction after mixing is less in the compatible blending system, and related reports are rarely made on literature data.

Some of the performance parameters after blending of the polymers can be inferred from the theoretical values of addition, determined according to the following formula (only the main components are considered here, neglecting the components at a level of 2% and below):

P＝c₁P₁+c₂P₂

wherein P is the theoretical value of addition, P₁The corresponding parameter values for component 1 in the mixture, c₁Is its mass fraction, P₂The corresponding parameter value of component 2 in the mixture, c₂Is the mass fraction thereof. If the measured mixture parameter isThe greater the difference between the value and the theoretical value of the addition, the more pronounced the synergistic (or anti-synergistic) effect between the components.

From Table 1, it can be found that when the shear rate is 100s^-1When the actual blend apparent shear viscosity is about 33.8% (example 1) to 55.6% (example 4) lower than the addition theoretical value.

From Table 2, it can be found that when the shear rate is 1363s^-1When the actual blend apparent shear viscosity is about 26.9% (example 1) to 48.8% (example 5) lower than the addition theoretical value.

[ example 7]

All of the above 7 particles, including comparative examples 1-2 and examples 1-5, were subjected to Differential Scanning Calorimetry (DSC) tests according to the procedure described above, and the temperature decrease curves and the second temperature increase curves are shown in fig. 6 and 7. The glass transition temperature ('T') of each particle can be directly obtained from the particles by software_g") versus composition is shown in fig. 8.

It can be seen from fig. 6 that after adding CAB to PBS, the crystallinity of the former is significantly reduced, the temperature-decreasing crystallization peak temperature of the particles of example 1 is lower than that of comparative example 1, the crystallization peak area is lower, and the temperature-decreasing crystallization peaks are not substantially seen in examples 2 to 5. On the temperature rise curve, the melting temperature of example 1 was also lower than that of comparative example 1, the melting peak area was smaller (see FIG. 7), example 2 had crystallization and melting peaks during the temperature rise, but both peak areas were smaller, and the particles of examples 3-5 had neither crystallization peak nor melting peak during the temperature rise. From FIGS. 6-8, it can be seen that the mixed particles all have only one glass transition temperature ("T")_g") indicates that the compatibility of the components in the blended particles is good, and T_gThe value of (a) increases with increasing CAB content.

[ example 8 ]

All 7 of the above seeds, including comparative examples 1-2 and examples 1-5, were subjected to thermogravimetric analysis (TGA) testing according to the procedure described above, and the results of the testing are shown in fig. 9. As can be seen, the thermal decomposition curves of the particles after blending were substantially between those of comparative examples 1-2, indicating that the thermal stability of CAB and PBS did not change much before and after blending, consistent with expectations.

[ example 9 ]

All of the above 7 types of particles, including comparative examples 1-2 and examples 1-5, were subjected to melt index (MFR) testing (190 ℃,2.16kg) according to the procedure described above, and the relationship between the measured MFR values and the composition is shown in FIG. 10. The specific values obtained from FIG. 10 are shown in Table 3, which includes the "theoretical values for addition" mentioned above.

From Table 3, it can be seen that the actual melt index of example 1 after melt blending of the components is 4.5g/10min higher than the theoretical value of addition, the percentage being about 93.5%, which is the smallest value of the percentages in examples 1-5; the actual melt index of example 4 was 15.2g/10min higher than the theoretical value of addition, the percentage being about 274%, and the percentage being the largest among examples 1-5. The other examples are between 93.5% and 274% higher than the addition theory. These unusually high melt indices are unexpected, rare in compatible polymer blend systems, and not yet found in CAB and PBS blends.

[ example 10 ]

3D printing wire prepared on a Malvern instruments sRosand RH7 capillary rheometer equipped with a Haul-Off/Melt Strength device, equipped with a circular die with a diameter of about 2mm, particles prepared in examples 3 and 5 were loaded into a total of about 50 grams of sample in multiple material chambers, each time compacted with a compression bar, and after the sample was loaded, a pre-pressing and pre-heating process was performed with a pre-pressing set pressure of 0.5MPa and a pre-heating time of 2 minutes. After the sample is melted, the sample is extruded out through an oral die under the pressure of a pressure lever, the speed of the pressure lever is 30mm/min, the extruded wire reaches a winding roller after passing through a plurality of groups of rollers, and the diameter of the wire is controlled by adjusting the traction speed. Specific parameters are shown in table 4.

As shown in table 4, for samples with different content compositions, 3D printing wires were prepared by controlling the heating temperature, the press bar speed, and the roller speed. The hardening speed and the softness of the wire vary for different blend compositions, with a higher glass transition temperature of the material at higher CAB contents (example 5), the wire drawn from the die being able to harden too quickly and the wire obtained being harder, and with a lower CAB content (example 3), the glass transition temperature being lower, the wire requiring a longer time to harden and the sample obtained being relatively softer.

[ example 11 ]

3D printed wires prepared in example 10 were 3D printed on a MakerBot Replicator 2X 3D printer. The bar size was set to 130.97X 12.70X 3.20mm rectangular parallelepiped by MakerBot desktop.Lnk software and the printing parameters were specified as resolution (resolution) standard, nozzle extrusion speed 90mm/s, travel speed 150mm/s, bar fill 100%, height of each layer 200 μm, nozzle temperature 190 ℃ and sole plate temperature 60 ℃. The file is saved to STL format and transmitted to the printer (MakerBot Replicator 2X).

The wire prepared in example 3 was too soft after melting and difficult to feed. The wire prepared in example 5 can be laid smoothly, and a cuboid sample strip can be printed well. The wire prepared from pure CAB (comparative example 2) also had good 3D printing performance, but had the following disadvantages in comparison: the printing temperature and the soleplate temperature need 230 ℃ and 110 ℃ respectively, both are higher than that of the embodiment 5, and the energy consumption is higher; the sample strips harden faster, resulting in easy warping; the product is brittle and has poor toughness. Therefore, the blend disclosed by the invention can be used for smoothly preparing 3D printing wires, has excellent 3D printing performance compared with raw materials, and obtains good technical effects.

TABLE 1180 ℃ shear rate of 100s^-1Measured apparent shear viscosity, theoretical apparent shear viscosity, and difference and percentage difference between the two

TABLE 2180 ℃ measured apparent shear viscosity at a shear rate of 1363s-1, theoretical apparent shear viscosity, and difference and percent difference between the two

Table 3 measured melt index (190 ℃,2.16kg) and addition theoretical melt index and the difference and percent difference between the two

TABLE 4 processing conditions for preparing 3D printing wire

Claims (10)

1. A3D printing wire contains a graft modified thermoplastic cellulose and aliphatic polyester blend, and the graft modified thermoplastic cellulose and aliphatic polyester blend is prepared from the following raw materials in parts by mass:

(1)20 to 80 parts of thermoplastic cellulose;

(2)80 to 20 parts of an aliphatic polyester;

(3)0.1 to 10 parts of a reactive monomer;

(4)0.01 to 1 part of an initiator;

the polyester blend is characterized in that a reactive monomer in the blend is at least grafted onto one of thermoplastic cellulose and aliphatic polyester, wherein the thermoplastic cellulose is at least one of cellulose acetate butyrate ester, cellulose acetate valerate, cellulose acetate caproate ester, cellulose acetate enanthate ester, cellulose acetate caprylate ester, cellulose acetate pelargonate ester, cellulose acetate caprate ester, cellulose acetate laurate ester, cellulose acetate palmitate, cellulose acetate stearate, cellulose propionate butyrate ester, cellulose propionate valerate ester, cellulose propionate caproate, cellulose propionate enanthate ester, cellulose propionate caprylate ester, cellulose propionate pelargonate ester, cellulose propionate caprate ester, cellulose propionate laurate ester, cellulose propionate stearate ester, the aliphatic polyester is a polyester formed by condensing α omega-aliphatic diacid or derivatives thereof containing 2 to 22 carbon atoms in the main chain and aliphatic diol, and the reactive monomer is at least one of hydroxyalkyl acrylate and hydroxyalkyl methacrylate.

2. The 3D printing filament according to claim 1, wherein the melt viscosity of the blend is at a low shear rate of 100s^-1Under the condition of at least 30% lower than the blending addition theoretical value of thermoplastic cellulose and aliphatic polyester, and has high shear rate of 1363s^-1Under the condition, the additive is at least 25 percent lower than the blending addition theoretical value raw material of the thermoplastic cellulose and the aliphatic polyester.

3. The 3D printing filament according to claim 1, wherein the degree of substitution of the thermoplastic cellulose is greater than 1.0.

4. The 3D print filament according to claim 1, wherein said aliphatic polyester comprises an extended aliphatic polyester.

5. The 3D printing filament according to claim 1, characterized in that the initiator is a radical initiator.

6. The 3D printing wire according to claim 5, wherein the initiator is at least one of a peroxide initiator and an azo initiator.

7. The 3D print wire according to claim 6, wherein said initiator is at least one of acyl peroxide, alkyl peroxide, perester, alkyl hydroperoxide, ketone peroxide, azo compounds.

8. The 3D print wire according to claim 7, wherein said initiator is at least one of benzoyl peroxide, azobisisobutyronitrile, dicumyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, benzoic peroxide, 2, 5-dimethyl-2, 5-di-t-butyl peroxy hexane.

9. The 3D print wire according to claim 8, wherein said initiator is at least one of benzoyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butylperoxyhexane.

10. A method for preparing a 3D printing wire material as claimed in any one of claims 1 to 9, wherein continuous melt blending extrusion is adopted, required amounts of all components are uniformly mixed in a molten state, and extrusion granulation is carried out to obtain blend particles; and melting and extruding the blend particles in an extruding device, and preparing the 3D printing wire through a die.

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