CN115975150B - Organosilicon modified thermoplastic polyurethane resin for 3D printing and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of 3D printing thermoplastic polyurethane materials, and particularly relates to an organosilicon modified thermoplastic polyurethane resin for 3D printing and a preparation method thereof. The organic silicon modified thermoplastic polyurethane resin for 3D printing comprises a component A and a component B, wherein the component A is an-OH blocked polyurethane prepolymer prepared by reacting polyol and isocyanate, and the R value of the component A is 0.95-0.98; the component B comprises NCO end-capped organosilane and catalyst; the molar ratio of-OH in the A component to-NCO in the B component is 1:1. The invention improves the temperature resistance of polyurethane resin and improves the mechanical strength of melt, thereby ensuring the feeding stability when being used for 3D printing, and having good mechanical property and better melt fluidity. The invention also provides a scientific and reasonable preparation method.

Description

Organosilicon modified thermoplastic polyurethane resin for 3D printing and preparation method thereof

Technical Field

The invention belongs to the technical field of 3D printing thermoplastic polyurethane materials, and particularly relates to an organosilicon modified thermoplastic polyurethane resin for 3D printing and a preparation method thereof.

Background

The 3D printing technology is one kind of fast forming technology, also called additive producing technology, and is one kind of technology based on digital model file and with plastic, metal or other adhesive material in strip, sheet or powder grain form, and through layer-by-layer printing. Thermoplastic polyurethane resin (TPU) is also widely applied to 3D printing and forming various parts due to excellent material performance, and the 3D printing and forming technology of the TPU material at present mainly comprises a Fused Deposition Modeling (FDM) technology and a Selective Laser Sintering (SLS) technology, wherein the SLS technology has higher printing cost and is mainly used for printing and forming parts of TPU materials with small size and high precision, and the FDM technology has simple operation, low equipment cost and wide raw materials, so that the FDM technology is more suitable for printing and forming parts with large size by utilizing the TPU material.

In the chinese patent document CN113493603a, "a heat-resistant polyurethane material for 3D printing, a method for manufacturing the same, and a printing method thereof", a heat-resistant polyurethane material is obtained by blending talc powder with a terephthalyl thermoplastic polyurethane elastomer, and is used for integrated 3D printing molding of large-sized non-pneumatic tires. However, the difficulty of the method is that the talcum powder is difficult to be uniformly dispersed in the TPU resin system during blending, which leads to unstable resin flow during printing of the blended resin, and thus the product quality is affected.

When the FDM technology is used for feeding, the feeding gear is oppositely rotated to generate pressure so as to further send the material into the melt tank, and the material is heated and melted in the melt tank and then is sprayed out through the printing nozzle, so that 3D printing is realized. The raw materials used for printing are required to have certain temperature resistance in a feeding pipe, and the resin has certain melt strength after being melted, so that large traction force is ensured to be generated between two wheels, and in addition, the resin has better fluidity when being extruded from a printing nozzle, so that high-precision printing is realized.

At present, the number of the products of thermoplastic polyurethane resin materials specially used for 3D printing and forming is relatively small, and most thermoplastic polyurethane resin materials used for 3D printing are applied to 3D printing after the thermoplastic polyurethane materials with mature marks on the market are subjected to physical blending modification. The blending modification has no unified specification, and the consistency of the performance of the printed product is difficult to be ensured.

Disclosure of Invention

In order to solve the problems, the invention provides the organic silicon modified thermoplastic polyurethane resin for 3D printing, which improves the temperature resistance of the polyurethane resin and improves the mechanical strength of a melt, thereby ensuring the feeding stability when being used for 3D printing, and has good mechanical property and better melt fluidity. The invention also provides a scientific and reasonable preparation method.

The organic silicon modified thermoplastic polyurethane resin for 3D printing comprises a component A and a component B, wherein the component A is an-OH blocked polyurethane prepolymer prepared by reacting polyol and isocyanate, and the R value of the component A is 0.95-0.98;

the component B comprises NCO end-capped organosilane and catalyst;

the molar ratio of-OH in the A component to-NCO in the B component is 1:1.

The polyol is a polyglycol.

The polyglycol is one or two of polyester glycol and polyether glycol.

The polyol includes one or more of polycaprolactone diol, polycarbonate diol, polybutylene adipate diol, polyethylene glycol adipate, and polytetrahydrofuran ether diol.

The isocyanate includes one or more of diphenylmethane diisocyanate (MDI), toluene Diisocyanate (TDI), hexamethylene Diisocyanate (HDI) and isophorone diisocyanate (IPDI).

The NCO-blocked organosilane includes one or more of propyltrimethoxysilane isocyanate, propyltriethoxysilane isocyanate, isopropylmethyldimethoxysilane isocyanate and propylmethyldiethoxysilane isocyanate.

The catalyst comprises one or more of triethanolamine, N-dimethylethanolamine and N, N' -lutidine.

From the standpoint of adjusting the molecular chain structure of polyurethane resin and further changing the processing characteristics, the invention focuses on introducing a small molecular organosilicon auxiliary agent, and seeking the balance state of the mechanical strength and the processing fluidity of the thermoplastic polyurethane melt by adjusting the R value (namely the isocyanate index and the molar ratio of isocyanate group-NCO to hydroxyl group-OH) of the thermoplastic polyurethane and changing the usage amount of isocyanate. The flow characteristic of the thermoplastic polyurethane elastomer material after melting has a great relation with the structure of the resin, isocyanate and a chain extender are used as hard segment parts in chain segments to mainly contribute to the hardness index of the polyurethane resin and influence the processing fluidity of the resin after melting, and after introducing an organosilicon chain segment into the polyurethane resin chain segment, the temperature resistance and mechanical property of the polyurethane resin can be obviously improved. In view of the above, the invention develops an organosilicon modified thermoplastic polyurethane resin material with high melt strength and good processing fluidity for 3D printing. The reaction mechanism of the invention is as follows:

。

the preparation method of the organic silicon modified thermoplastic polyurethane resin for 3D printing comprises the following steps:

(1) Vacuum dehydrating the polyol at 110-120 ℃ for 1-2 h, cooling to 70-75 ℃, then keeping a vacuum state, dripping isocyanate by using a constant pressure dripping funnel for 1.5-2.5 h, and reacting for 2-3 h after dripping to obtain a component A;

(2) Mixing NCO end capped organosilane and catalyst to obtain component B;

(3) And (3) uniformly mixing A, B components, heating to 80-120 ℃ and keeping the temperature for 0.5-2 hours to obtain the composite material.

Compared with the prior art, the invention has the beneficial effects that:

1. the introduction of the organic silicon chain segment can improve the temperature resistance of the polyurethane resin, so that the melt strength of the thermoplastic polyurethane is improved when 3D printing is carried out, and the thermoplastic polyurethane resin is prevented from being broken under the pressure effect generated by the opposite rotation of a feeding gear of a 3D printer, so that the feeding stability is ensured;

2. the organic silicon chain segment introduced in the invention adopts-NCO end-capped organic silane, and the thermoplastic polyurethane resin obtained through the reaction of-NCO and-OH excessive polyurethane prepolymer of the organic silane has higher mechanical property than the polyurethane resin without the organic silicon chain segment, in addition, the flexibility of the organic silicon chain segment is better, so that the modified thermoplastic polyurethane resin has better melt fluidity;

3. compared with physical modification, the preparation of the organosilicon modified thermoplastic polyurethane resin provided by the invention belongs to chemical modification, and the organosilicon modified thermoplastic polyurethane resin has the advantages that the condition of uneven dispersion is avoided, and the stability of the product quality is ensured to a great extent.

Detailed Description

The technical scheme of the present invention will be clearly and completely described in the following examples.

All materials used in the examples are commercially available, except as specified.

Example 1

Preparing a component A: firstly, adding 500g of polycarbonate diol (with a hydroxyl value of 55mgKOH/g and a number average molecular weight of 2040) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 120 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 1.5h to finish vacuum dehydration of the polycarbonate diol, cooling to 70 ℃, slowly adding 39.1g of hexamethylene diisocyanate through the constant-pressure dropping funnel (the adding amount of the hexamethylene diisocyanate is calculated according to R=0.95), and reacting for 2h to obtain the-OH terminated polyurethane prepolymer;

and (3) preparing a component B: uniformly mixing 5.06g of isocyanatopropyl trimethoxysilane and 2.53g of triethanolamine, wherein the usage amount of the isocyanatopropyl trimethoxysilane is calculated according to the mole ratio of-OH in the component A to-NCO in the isocyanatopropyl trimethoxysilane being 1:1;

and uniformly stirring the component A and the component B, heating to 90 ℃ and keeping stirring for 1.5 hours to obtain the organosilicon modified thermoplastic polyurethane resin for 3D printing.

Example 2

Preparing a component A: firstly, adding 500g of poly (diethylene glycol adipate) (with a hydroxyl value of 55mgKOH/g and a number average molecular weight of 2040) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 120 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 1h to finish vacuum dehydration of the poly (diethylene glycol adipate), cooling to 75 ℃, slowly adding 58.8g of diphenylmethane diisocyanate (the addition amount of the diphenylmethane diisocyanate is calculated according to R=0.96) through the constant-pressure dropping funnel, and reacting for 2h to obtain the-OH-terminated polyurethane prepolymer;

and (3) preparing a component B: uniformly mixing 4.89g of isocyanatopropyl triethoxysilane and 2.45g of N, N-dimethylethanolamine, wherein the usage amount of the isocyanatopropyl triethoxysilane is calculated according to the mole ratio of-OH in the component A to-NCO in the isocyanatopropyl triethoxysilane of 1:1;

and uniformly stirring the component A and the component B, heating to 90 ℃ and keeping stirring for 2 hours to obtain the organosilicon modified thermoplastic polyurethane resin for 3D printing.

Example 3

Preparing a component A: firstly, adding 600g of polytetrahydrofuran ether glycol (with a hydroxyl value of 55mgKOH/g and a number average molecular weight of 2040) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 100 ℃, keeping the vacuum degree at-0.3 MPa, continuously stirring for 2 hours to finish vacuum dehydration of polytetrahydrofuran ether glycol, cooling the temperature to 70 ℃, and slowly adding 49.6g of toluene diisocyanate (the addition amount of toluene diisocyanate is calculated according to R=0.97) through the constant-pressure dropping funnel, and reacting for 3 hours to obtain an-OH-terminated polyurethane prepolymer;

and (3) preparing a component B: 3.42g of isocyanatopropyl methyl dimethoxy silane and 1.71g of triethanolamine are uniformly mixed, wherein the usage amount of the isocyanatopropyl methyl dimethoxy silane is calculated according to the mole ratio of the-OH content in the component A to the-NCO in the isocyanatopropyl methyl dimethoxy silane of 1:1;

and uniformly stirring the component A and the component B, heating to 110 ℃ and keeping stirring for 0.5h, thus obtaining the organosilicon modified thermoplastic polyurethane resin for 3D printing.

Example 4

Preparing a component A: firstly, adding 600g of polycaprolactone diol (with a hydroxyl value of 70mgKOH/g and a number average molecular weight of 1600) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 110 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 1h to finish vacuum dehydration of the polycaprolactone diol, cooling to 70 ℃, slowly adding 81.6g of isophorone diisocyanate (the addition amount of isophorone diisocyanate is calculated according to R=0.98) through the constant-pressure dropping funnel, and reacting for 3h to obtain the-OH-terminated polyurethane prepolymer;

and (3) preparing a component B: 3.23g of isocyanatopropyl methyl diethoxysilane and 1.62g of N, N' -lutidine are uniformly mixed, wherein the usage amount of the isocyanatopropyl methyl diethoxysilane is calculated according to the mole ratio of-OH in the component A to-NCO in the isocyanatopropyl methyl diethoxysilane of 1:1;

and uniformly stirring the component A and the component B, heating to 100 ℃ and keeping stirring for 1.5 hours to obtain the organosilicon modified thermoplastic polyurethane resin for 3D printing.

Example 5

Preparing a component A: firstly, adding 500g of polybutylene adipate glycol (with a hydroxyl value of 55mgKOH/g and a number average molecular weight of 2040) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 120 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 1h to finish vacuum dehydration of the polybutylene adipate glycol, cooling to 75 ℃, slowly adding 40.9g of toluene diisocyanate (the addition amount of the toluene diisocyanate is calculated according to R=0.96) through the constant-pressure dropping funnel, and reacting for 2h to obtain an-OH-terminated polyurethane prepolymer;

and (3) preparing a component B: uniformly mixing 4.97g of isocyanatopropyl triethoxysilane and 2.49g of N, N-dimethylethanolamine, wherein the usage amount of the isocyanatopropyl triethoxysilane is calculated according to the mole ratio of-OH in the component A to-NCO in the isocyanatopropyl triethoxysilane of 1:1;

and uniformly stirring the component A and the component B, heating to 100 ℃ and keeping stirring for 1h to obtain the organosilicon modified thermoplastic polyurethane resin for 3D printing.

Comparative example 1

Preparing a component A: firstly, adding 600g of polytetrahydrofuran ether glycol (with a hydroxyl value of 55mgKOH/g and a number average molecular weight of 2040) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 115 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 2 hours to finish vacuum dehydration of polytetrahydrofuran ether glycol, cooling to 75 ℃, slowly adding 69.9g of diphenylmethane diisocyanate (the addition amount of the diphenylmethane diisocyanate is calculated according to R=0.95) through the constant-pressure dropping funnel, and reacting for 2 hours to obtain the-OH terminated polyurethane prepolymer;

and (3) preparing a component B: 10.64g of triphenylmethane triisocyanate, wherein the usage amount of the triphenylmethane triisocyanate is calculated according to the mole ratio of-OH in the component A to-NCO in the triphenylmethane triisocyanate of 1:1;

and uniformly stirring the component A and the component B, heating to 120 ℃ and keeping stirring for 2 hours to obtain the thermoplastic polyurethane resin.

Comparative example 2

Preparing a component A: firstly, adding 600g of polytetrahydrofuran ether glycol (with a hydroxyl value of 70mgKOH/g and a number average molecular weight of 1600) into a four-neck flask which is provided with a polytetrafluoroethylene stirring paddle, a constant-pressure dropping funnel, a snake-shaped condenser pipe and nitrogen protection, heating the four-neck flask to 120 ℃, keeping the vacuum degree at-0.1 MPa, continuously stirring for 2 hours to finish vacuum dehydration of polytetrahydrofuran ether glycol, cooling the temperature to 70 ℃, slowly adding 62.64g of toluene diisocyanate (the addition amount of toluene diisocyanate is calculated according to R=0.96) through the constant-pressure dropping funnel for 2 hours, and reacting for 2 hours to obtain an-OH terminated polyurethane prepolymer;

and (3) preparing a component B: 11.01g of triphenylmethane triisocyanate, wherein the usage amount of the triphenylmethane triisocyanate is calculated according to the mole ratio of-OH in the component A to-NCO in the triphenylmethane triisocyanate of 1:1;

and uniformly stirring the component A and the component B, heating to 110 ℃ and keeping stirring for 1.5 hours to obtain the thermoplastic polyurethane resin.

Performance testing

The polyurethane materials prepared in examples 1 to 5 and comparative examples 1 to 2 were tabletted, the mechanical properties of the materials were tested, and the melt strength of the polyurethane materials was characterized by using a melt flow rate tester, and the test results are shown in table 1.

The melt strength test is specifically: the quality of the melt was characterized by testing the mass of the melt from the die of the melt flow rate meter suspended to break for a period of time, keeping the melt in a cylinder at 224 ℃ for 6min, extruding it completely from the capillary tube with a weight of 8.7kg, while a small portion of the melt was suspended at the outlet of the die, recording the time of the melt flowing out of the die outlet to break, weighing the mass of the broken material, testing 4 times per sample, and calculating the mass of the extrudate suspended at the die outlet for 10min by interpolation, the higher the mass of the extrudate, the higher the melt strength of the resin.

The test of the Shore hardness (Shore A) of the material is carried out with reference to GB/T531-1999 and the test of the mechanical properties of the material is carried out with reference to GB/T528-2009.

Table 1 performance test tables for examples 1 to 5 and comparative examples 1 to 2

From the table, the test results of comparative examples 1-5 and comparative examples 1-2 show that the introduction of the small molecule-NCO-terminated organosilane effectively improves the mechanical properties of polyurethane resin, and the tensile strength and elongation at break of polyurethane are obviously improved; because the flexibility of the introduced organosilicon chain segments is particularly good, the thermoplastic polyurethane resin modified by using the small molecular organosilane has higher melt strength in a melt state.

From the test results of example 2 and example 5, polyurethane resins prepared using diisocyanate having a benzene ring and polyester diol have higher hardness values.

Claims (5)

1. The organic silicon modified thermoplastic polyurethane resin for 3D printing is characterized by comprising a component A and a component B, wherein the component A is an-OH blocked polyurethane prepolymer prepared by reacting polyol and isocyanate, and the R value of the-OH blocked polyurethane prepolymer is 0.95-0.98;

the component B comprises NCO end-capped organosilane and catalyst;

the molar ratio of-OH in the component A to-NCO in the component B is 1:1;

the polyalcohol is polyglycol;

the isocyanate comprises one or more of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate;

the NCO-blocked organosilane includes one or more of propyltrimethoxysilane isocyanate, propyltriethoxysilane isocyanate, isopropylmethyldimethoxysilane isocyanate and propylmethyldiethoxysilane isocyanate.

2. The silicone-modified thermoplastic polyurethane resin for 3D printing of claim 1, wherein the polyglycol is one or both of a polyester glycol and a polyether glycol.

3. The silicone-modified thermoplastic polyurethane resin for 3D printing of claim 1, wherein the polyol comprises one or more of polycaprolactone diol, polycarbonate diol, polybutylene adipate diol, polyethylene glycol adipate, and polytetrahydrofuran ether diol.

4. The silicone-modified thermoplastic polyurethane resin for 3D printing of claim 1, wherein the catalyst comprises one or more of triethanolamine, N-dimethylethanolamine, and N, N' -dimethylpyridine.

5. A method for producing the silicone-modified thermoplastic polyurethane resin for 3D printing according to any one of claims 1 to 4, comprising the steps of:

(1) Vacuum dehydrating the polyol at 110-120 ℃ for 1-2 h, cooling to 70-75 ℃, then keeping a vacuum state, dripping isocyanate by using a constant pressure dripping funnel for 1.5-2.5 h, and reacting for 2-3 h after dripping to obtain a component A;

(2) Mixing NCO end capped organosilane and catalyst to obtain component B;

(3) And (3) uniformly mixing A, B components, heating to 80-120 ℃ and keeping the temperature for 0.5-2 hours to obtain the composite material.