CN113929869B

CN113929869B - Two-component polyurea material for 3D printing and method for 3D printing of polyurea product

Info

Publication number: CN113929869B
Application number: CN202111432462.7A
Authority: CN
Inventors: 王占华; 夏和生
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-08-16
Anticipated expiration: 2041-11-29
Also published as: CN113929869A

Abstract

The invention provides a two-component polyurea material for 3D printing and a method for 3D printing a polyurea product, comprising A, B components; the component A is one or a mixture of more of polyether, polyester and polyolefin with end capping of amino group, or one or a mixture of more of polyether, polyester and polyolefin with amino group at the side chain; the component B consists of a compound containing isocyanate groups and a compound containing blocked isocyanate, and the mass ratio of the compound containing isocyanate groups to the compound containing blocked isocyanate is 3:1 to 1: 4. The A, B components are mixed in a pumping printing cavity, extruded and printed by pressure, solidified by laser, and circularly repeated until the printing is finished. The printing method realizes direct-writing 3D printing, can print polyurea products with special complex structures, has the strength in the Z direction of the printed products reaching more than 85 percent of that of an XY plane, can obtain products with different mechanical properties, including elastomers, thermosetting resins and the like, has adjustable transparency of the printed products, and can be used for preparing damping soles, children toys, artware and the like.

Description

Two-component polyurea material for 3D printing and method for 3D printing of polyurea product

Technical Field

The invention belongs to the technical field of 3D printing, and particularly relates to a two-component polyurea material for 3D printing and a method for 3D printing of a polyurea product.

Background

Polyurea is an elastomeric material formed by the reaction of an isocyanate component and an amino compound component. The polyurea is divided into pure polyurea and semi-polyurea, the performances of the pure polyurea and the semi-polyurea are different, and the most basic characteristics of the polyurea are corrosion resistance, water resistance, wear resistance and the like. The polyurea protective coating has no solvent and pollution, can be quickly formed on the surface of a material to form an integrally compact, continuous and seamless high-strength and high-elasticity coating, and has good wear resistance, impact resistance and marine climate aging resistance. The existing polyurea protective coating is prepared by reacting an R component consisting of high-activity end amino polyether and polyamine chain extender with an A component consisting of polyisocyanate prepolymer, and because the reaction speed between amino and NC0 groups is very high, the film forming speed is too high, so that the bonding force between the coating and a base material and the adhesive force between the coatings are poor, even discontinuous coatings and other defects occur, and a lot of difficulties are brought to construction.

The most common processing method for polyureas is spray coating, which is suitable for producing protective coatings on a variety of substrates. In addition, the reaction extrusion molding method can also be used for spraying construction of polyurea. There are few reports on the polyurea 3D printing technology, and the technology is generally a photocuring 3D technology.

In recent years, polyurea also has wide application in the fields of vibration reduction and sound absorption damping of military equipment. The polyurea material with a special structure is constructed by using the 3D printing technology, so that the performances of vibration reduction, sound absorption and damping and the like of the polyurea material can be improved, the application of the polyurea material in the military field is further improved, and the polyurea material has important significance.

Application No.: 2019107906039 provides a photosensitive resin and a method for 3D printing polyurea, the photosensitive resin includes acrylate oligomer containing urea bond and having a functionality of 2 or more; the acrylate oligomer containing urea bonds and having double-bond functionality more than or equal to 2 is obtained by reacting isocyanate group-terminated compounds having functionality more than or equal to 2 with acrylate or methacrylate compounds containing amino. The invention also provides a 3D polyurea printing method. After the photosensitive resin provided by the invention is photocured or 3D printed to form a polymer, the molecular structure, crosslinking density and other network structure characteristics of the polymer can be changed through specific post-treatment, so that the thermal and mechanical properties of the polymer can be adjusted through the post-treatment. This patent adopts photocuring technique to carry out 3D and prints, and it clears away the difficulty to print goods surface monomer, and environmental pollution is serious, and printable monomer kind is limited, is not suitable for two ingredient polyurea curing techniques commonly used.

CN 113166355a provides a 3D printing method of a two-component polyurethane composition, comprising the steps of: -providing a pumpable first component a comprising: at least one polyol having an OH functionality in the range from 1.5 to 4 and an average molecular weight (number average) Mn in the range from 250 to 15000g/mol, and preferably at least one diol having two hydroxyl groups connected by a C2-to C9-carbon chain, and at least one compound T having at least one thiol group; -feeding a pumpable second component B in the mixing zone of a continuous mixer, wherein the second component B comprises at least one polyisocyanate I; -wherein one of the two components a and B further comprises at least one metal catalyst for the reaction of hydroxyl groups and isocyanate groups, said metal catalyst being capable of forming a sulfur-containing complex, and the molar ratio of all mercapto groups of the at least one compound T to all metal atoms of the at least one metal catalyst is between 1:1 and 250: 1. The method prints a polyurethane system, a metal catalyst is needed to adjust the curing rate of the AB component, the metal catalyst has a large influence on the performance of printed products, and the printed products contain sulfur elements and are easy to yellow and degrade.

CN101531861A provides a two-component spray polyurea waterproof coating, a preparation method and a construction method thereof, and a preparation method and a construction method thereof, wherein the waterproof coating comprises a component A and a component B, and a raw material system of the component A comprises 40-60 parts by weight of polyisocyanate, 30-45 parts by weight of polyether polyol and 5-15 parts by weight of hydroxyl silicone oil; the raw material system of the component B comprises 35-60 parts of amine-terminated polyether, 20-45 parts of amine chain extender and 5-20 parts of amino silicone oil. The waterproof material formed by the waterproof coating combines the excellent performances of the polyurea elastomer and the organosilicon material, has high overall physical performance, excellent color retention and ultraviolet resistance, can be applied to waterproof engineering exposed in the atmospheric environment, and is particularly suitable for waterproof coatings of roads and bridges of passenger special lines. The preparation method of the waterproof coating is simple in process and environment-friendly. The construction method of the waterproof coating can ensure that the coating can effectively wet and permeate the base material on the surface of the base material, so that the formed waterproof coating has better appearance. Polyurea is mostly prepared by a two-component spraying process, is used for various waterproof and anticorrosive coatings, and is prepared from a coating material instead of a product with a special structure and function.

Disclosure of Invention

The invention provides a two-component polyurea material for 3D printing and a method for 3D printing of polyurea products, which realize the two-component polyurea direct-writing 3D printing: the reaction rate of amino and isocyanate is very fast, the nozzle is easily blocked, 3D printing is difficult to realize, and the curing rate of amino and isocyanate and the system viscosity are adjusted by introducing blocked isocyanate, so that the bi-component polyurea direct-writing 3D printing is realized.

The two-component polyurea material for 3D printing comprises A, B components;

the component A is one or a mixture of more of polyether, polyester and polyolefin with end capping of amino group, or one or a mixture of more of polyether, polyester and polyolefin with amino group at the side chain;

the component B consists of a compound containing isocyanate groups and a compound containing blocked isocyanate, and the mass ratio of the compound containing isocyanate groups to the compound containing blocked isocyanate is 3:1 to 1: 4.

The mass ratio of the A, B components is 3:1 to 1: 3.

The compound containing isocyanate groups is one or a mixture of more of toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate tripolymer, toluene diisocyanate tripolymer and diphenylmethane diisocyanate tripolymer.

The isocyanate blocking agent adopted in the blocked isocyanate-containing compound is one of methyl ethyl ketone, oxime, substituted phenol or secondary amine.

The application of the two-component polyurea material for 3D printing is used as a 3D printing material.

The method for 3D printing of the polyurea product adopts the two-component polyurea material for 3D printing; the method comprises the following steps:

the A, B components are mixed in a pumping printing cavity, extruded and printed by pressure, solidified by laser, and circularly repeated until the printing is finished.

Wherein the extrusion feed ratio of the printer is between 1:1 and 2: 1.

The printing speed of the printer is 200-800 mm/min.

The laser of the printer is a broad-spectrum light source, and the laser curing time is as follows: 30 seconds to 200 seconds.

The polyurea product obtained by the invention has better mechanical strength, the tensile strength can reach 10-60MPa, and the elongation at break is 3% -2000%.

The Z-direction intensity of the printed article can be up to 85% or more of the XY plane.

The printed product of the invention can be used for preparing shock-absorbing soles, children toys, artware and the like.

The technical scheme of the invention has the following beneficial effects:

1) a, B components are mixed by a printer to realize direct-writing 3D printing, and polyurea products with special complex structures can be printed;

2) in the mixing process of the A, B components, the amino compound firstly reacts with the isocyanate compound to realize precuring, increase the viscosity of the system and ensure that the printed product can keep the shape on the substrate;

3) the blocked isocyanate is removed after laser heating, and the blocked isocyanate is continuously subjected to curing reaction with amino to generate a product with better mechanical strength, and the blocking agent can be freely volatilized and removed;

4) the introduction of the blocked isocyanate has the beneficial effects of avoiding blockage of a spray head due to too fast curing of amino and isocyanate;

5) the urea bonds on the polyurea molecular chains can form hydrogen bonds and can perform exchange reaction at high temperature, so that the strength of the printed product in the Z direction can reach more than 85 percent of the strength of an XY plane;

6) by changing the chemical components of the components, products with different mechanical properties can be obtained, including elastomers, thermosetting resins and the like, and the transparency of printed products can also be adjusted;

7) the printed product can be used for preparing shock-absorbing soles, children toys, artware and the like.

Drawings

FIG. 1 is a stress-strain curve of a printed article of example 1;

FIG. 2 is an optical photograph of the printed article of example 1;

FIG. 3 is a stress-strain curve of the printed article of example 2;

FIG. 4 is an optical photograph of the printed article of example 2;

FIG. 5 is the tensile strength of the separately printed articles of example 3 in the direction X, Y, Z;

fig. 6 is the elongation at break of the separately printed articles in the direction X, Y, Z in example 3.

Detailed Description

The specific technical scheme of the invention is described by combining the embodiment.

Example 1

10g of dipropylamine and 16.63g of hexamethylene diisocyanate were mixed and stirred at room temperature for 24 hours to obtain a blocked isocyanate-containing compound.

The component A is amino-terminated polypropylene glycol with the molecular weight of 4000, the component B is a mixture of toluene diisocyanate and a compound containing the terminated isocyanate obtained in the previous step, the mass ratio of the toluene diisocyanate to the compound containing the terminated isocyanate is 1:2, the mass ratio of the component A, B is 3:1, the printing speed is 300mm/min, the laser curing time is 60 seconds, and 3D printing is carried out.

As shown in FIG. 1, the breaking elongation of the polyurea prepared by the 3D printing method can reach 440%, and the polyurea has good flexibility.

As shown in fig. 2, a transparent polyurea product having a particularly complicated structure can be prepared by this 3D printing method.

Example 2

10g of dipropylamine and 17.8g of toluene diisocyanate were stirred at room temperature for 24 hours to obtain a blocked isocyanate-containing compound.

The component A is amino-terminated polypropylene glycol with the molecular weight of 230, the component B is a mixture of diphenylmethane diisocyanate and a blocked isocyanate-containing compound obtained in the previous step, the mass ratio of the diphenylmethane diisocyanate to the blocked isocyanate is 1:2, the mass ratio of the A, B component is 1:1, the printing speed is 200mm/min, the laser curing time is 120 seconds, and 3D printing is carried out.

As shown in FIG. 3, the breaking strength of the polyurea prepared by the 3D printing method can reach 57MPa, and the polyurea has good mechanical properties. Fig. 4 is an optical photograph of a printed article, from which it can be concluded that an opaque white polyurea article having a particularly complex structure can be prepared by this 3D printing method.

Example 3

10g of methyl ethyl ketoxime and 25.5g of isophorone diisocyanate were stirred at room temperature for 24 hours to obtain a blocked isocyanate-containing compound.

The component A is amino-terminated polyethylene glycol with the molecular weight of 400, the component B is a mixture of isophorone diisocyanate and a blocked isocyanate-containing compound obtained in the previous step, the mass ratio of the isophorone diisocyanate to the blocked isocyanate is 1:1, the mass ratio of the A, B component is 1:1, the printing speed is 500mm/min, the laser curing time is 60 seconds, and 3D printing is carried out.

Fig. 5 shows the tensile strength of the articles printed in X, Y, Z directions in example 3, from which it can be seen that the tensile strength of the articles printed in X, Y, Z three directions is substantially the same, and the strength in the Z direction can reach 90% of that in the X direction, indicating that the 3D printing technique can be used to obtain articles with isotropic mechanical properties.

Fig. 6 shows the elongation at break of the articles printed separately in direction X, Y, Z from example 3, from which it can be seen that the elongation at break of the articles printed in three directions X, Y, Z are substantially the same, illustrating that by this 3D printing technique an article can be obtained with isotropic mechanical properties.

Claims

The method for 3D printing of the polyurea product is characterized by adopting a two-component polyurea material for 3D printing;

the two-component polyurea material for 3D printing comprises A, B components;

the component A is one or a mixture of more of polyether, polyester and polyolefin with end capping of amino group, or one or a mixture of more of polyether, polyester and polyolefin with amino group at the side chain;

the component B consists of a compound containing isocyanate groups and a compound containing blocked isocyanate, and the mass ratio of the compound containing isocyanate groups to the compound containing blocked isocyanate is 3:1 to 1: 4; the isocyanate blocking agent adopted in the blocked isocyanate-containing compound is one of methyl ethyl ketone, oxime, substituted phenol or secondary amine;

the method comprises the following steps:

the A, B component is pumped to a printing cavity for mixing, extruded by pressure for printing, solidified by laser, and circularly repeated until the printing is finished.
2. The method for 3D printing of the polyurea product according to claim 1, wherein the printing speed of the printer is 200-800 mm/min.
3. The method of 3D printing a polyurea product according to claim 1, wherein the laser of the printer is a broad spectrum light source, and the laser curing time is: 30 seconds to 200 seconds.
4. The method of 3-D printing a polyurea product according to claim 1, wherein the A, B components are present in a mass ratio of between 3:1 and 1: 3.
5. The method of 3D printing a polyurea article according to claim 1, wherein the isocyanate group-containing compound is one or a mixture of toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate trimer, toluene diisocyanate trimer, and diphenylmethane diisocyanate trimer.