WO2020076279A1 - Precursor powder and binder for manufacturing ceramic items by three-dimensional printing - Google Patents

Abstract

The invention relates to the technology of industrial three-dimensional printing of ceramic items, in particular to a composition of powder ingredients - a precursor and a composition of binder ingredients. A powder is a precursor for the manufacture of ceramic items by three-dimensional printing and comprises the following components, wt%: 4-20 glaze, for example type VTR-100; 2-40 clay, for example type MKL-1; and the rest being, for example, aluminum oxide (in the form of a powder with a particle size of 4-50 μm). A binder for three-dimensional printing of ceramic items comprises the following components, wt%: 0.5-9.0 glycerin, 0.5-9.0 isopropyl alcohol, 0.3-5.0 PEG-7 (glyceryl cocoate), 5.0-30.0 ethylene glycol, and the rest being distilled water. When it is necessary to apply a certain color to a finished item, a water-soluble dye can also be added to the binder. The claimed invention improves consumer properties of the finished item, and also speeds up the manufacture both of one of the components (the precursor powder or binder) and of the ceramic item as a whole.

Description

 Precursor powder and binder for the manufacture of ceramic products by three-dimensional printing

 FIELD OF TECHNOLOGY

 The invention relates to the technology of industrial three-dimensional printing of 5 ceramic products, in particular to the composition of the ingredients of the precursor powder and the composition of the binder ingredients.

 For the manufacture of ceramic products by three-dimensional printing, for example, on a printer Z CGR 310, use a precursor powder and a binder.

 10 BACKGROUND OF THE INVENTION

 Closest to the precursor powder is the composition of the ingredients described in US patent Ns 8475946, publ. 07/02/2013, containing the following components, wt.%:

 clay 50-80

 15 feldspar 5-20

 refractory cement 2-10

 frit 2-10

 sodium silicate 0.5 -4.0

 This composition is selected as a prototype of the inventive powder -

20 precursor.

 The prototype and the claimed composition of the ingredients of the precursor powder have the following common features (components):

 - clay (as one of the components of the base; in US patent N ° 8475946, the base includes clay and feldspar);

 25 - melt (as a mellow composition according to US patent

Ns 8475946 contains a frit).

 The prototype composition has the following disadvantages.

1. When the powder pressing mechanism is not used, its density on different sides of the chamber is uneven (0.93 g / cm ³ on the right side, 1.1 1 g / cm on the left side of the print chamber) (see Table 2). It happens

SUBSTITUTE SHEET (RULE 26) due to the low flowability (less than 5 g / s) of the powder in front of the shaft (which rotates from left to right) at the beginning of the process of applying the powder to the print chamber, and also due to the large (over 20%) difference in bulk (0.82 g / cm ³ ) density and true (1.21 g / cm ³ ) density of the powder (see Table 1). The lower the density of the ceramic product, the lower its strength, and the greater the likelihood of its deformation during firing, and the uneven density makes these indicators poorly predictable, thereby worsening the quality of the product.

2. The compressive strength of products prepared from the specified powder does not exceed the value of 73 kg / cm ² , even when using the pressure mechanism (see Table 1).

 3. The powder product has a fire shrink of at least 10-12%, which requires an increase in the model at the printing stage and limits the available area of the print chamber.

4. The powder contains a respirable fraction in an amount of 6 mg / m ³ and a respirable fraction in an amount of 3 mg / m ³ , which creates an increased danger for the operator and contributes to clogging of the mechanical components of the 3 d-printer.

 Known binder composition for the manufacture of ceramic products by three-dimensional printing, which includes the following components:

 - polyvinyl alcohol (polyvinyl alcohol);

 - ethylene glycol;

 - glycerin;

 - distilled water

 (see US patent N ° 8475946, publ. 02.07.2013, the commercial name of the binder obtained by this patent is Tethon Ceramic Binder).

 The composition of this binder is selected as a prototype.

The prototype and composition of the claimed binder have the following common features: s

 - glycerin;

 - ethylene glycol;

 - secondary alcohol;

 - distilled water.

 The prototype composition has the following disadvantages:

- insufficient compressive strength, leading to an increased risk of damage to the product (up to 7 kg / cm ² );

- insufficient average density (up to 1100 kg / cm ³ ), which also leads to an increased risk of damage to the product;

 - the difficulty of obtaining a binder for three-dimensional printing of ceramic products, because it is necessary to carry out hydrolysis of polyvinyl alcohol by heat treatment and filtration, or the acquisition of similarly processed raw materials, which threatens dependence on suppliers.

 SUMMARY OF THE INVENTION

 The basis of the invention is the task to create a composition of the ingredients of the precursor powder and a composition of the binder ingredients for the manufacture of ceramic products by three-dimensional printing, which provide improved consumer properties of the finished product, accelerating the production of both one of the components and the ceramic product as a whole.

 The problem is solved by two inventions, united by a single inventive concept: the composition of the ingredients of the precursor powder and the composition of the binder ingredients for the manufacture of ceramic products by three-dimensional printing.

In the first invention, the task is solved by the composition of the ingredients of the powder - a precursor for the manufacture of ceramic products by three-dimensional printing containing clay and fluff so that, unlike the prototype, the composition additionally contains aluminum oxide, and as smoothing - glaze, with the following ratio of these components, May. %:

 glaze 4-20

 clay 2-40

 aluminum oxide rest

 In addition, the composition contains:

 - aluminum oxide in the form of a powder with a particle size of 40-50 microns;

- glaze brand VTR - 100;

 - clay mark MKL - 1.

 In the second invention, the task is solved by the composition of the binder ingredients for three-dimensional printing of ceramic products containing glycerin, ethylene glycol, secondary alcohol and distilled water, in that, unlike the prototype, the composition further comprises PEG-7, and it contains isopropyl alcohol as a secondary alcohol , in the following ratio of these components, May. %:

 glycerin 0, 5-9, 0

 isopropyl alcohol 0, 5-9, 0

 PEG-7 (glyceryl cocoate) 0, 3-5.0

 ethylene glycol 5.0-30.0

 distilled water the rest

 In addition, the composition further comprises a dye in an amount of 0, 5-4, 0 wt.%.

 New in the first invention is the introduction of an additional component, aluminum oxide, the replacement of flux, and also the mass ratio of the components.

 The achievement of the technical result in the first invention can be explained as follows.

The increase in flowability leads to a decrease in the difference in bulk and true density, as a result, the true and bulk density increases. Due to this, unevenness is greatly reduced powder distribution in the printing chamber, and also increases the strength of the product at all stages.

 Grades of clay and glaze, as well as the mass ratio of the components were found experimentally.

 Clay grade MKL-1 is a typical clay, which is available in many countries, including and in Ukraine. It is non-granulated clay and has a high density.

 Other brands of clay are known, including and granular, which can be used in the claimed composition, but they must first be ground in a mill.

 If the glaze is introduced in an amount of less than 4 wt.%. this will lead to destruction of the product during firing. If clay is introduced in an amount of less than 2 wt.% - this will lead to destruction of the product when removed from the print chamber. An increase in the amount of glaze (more than 20 wt.%) And clay (more than 40 wt.%) Leads to excessive deformation during firing.

 Clay performs 2 functions: a water absorber (binder) and a powder body (base). An increase in clay content (other than the above) also leads to a decrease in flowability, density, strength and an increase in shrinkage. A decrease in the amount of clay (less than 2 wt.%) Leads to the fact that the powder cannot adequately (sufficiently) saturate the binder and, as a result, the product loses its shape and its strength drops sharply (decreases) (see example Ns 6).

As indicated above, the glaze serves as a fusion substance (melt) at high temperature (970-1020 ° C). We have tested, in addition to the brand VTR-100, and other brands of glaze, which are also suitable as smoothing. They are suitable for use, but it is necessary to adjust (decrease or increase) the firing temperature. In connection with the above, the brand of glaze is insignificant. The choice of particle size of aluminum oxide can be explained as follows. It is desirable that the particle size in the powder A1 ₂ 0 ₃ be as small as possible, while maintaining high flowability.

 High flowability is achieved:

 - the hardness of the material - aluminum oxide is one of the most solid substances, and allows you to save flowability for particles less than 50 microns; the vast majority of clays become non-flowing with a fractional composition of less than 50 microns;

 - a small scatter in the particle size - hence 40-50 microns, that is, a limitation of 10 microns of scatter.

 New in the second invention is the presence of an additional component - PEG-7 (glyceryl cocoate), the replacement of secondary alcohol, as well as the mass ratio of the components.

 The achievement of the technical result in the second invention is ensured by the fact that the following indicators are increased:

- average density - (1237-1250 kg / m ³ ),

- compressive strength - (7.92-8.20 kg / cm ² ).

 In addition, the components of the claimed composition are readily available, which ensures the efficiency and economy of obtaining ceramic products that meet the requirements of the ceramic industry.

 OPTIMAL EMBODIMENT FOR CARRYING OUT THE FIRST INVENTION

The composition of the powder precursor ingredients for the manufacture of ceramic products by three-dimensional printing is prepared by mixing an aluminum oxide powder with a particle size of 40-50 microns with clay, for example, grade MKL-1, and with glaze, for example, grade VTR-100 in random order. The mixture of components is mixed for ~ 5 minutes. until complete homogenization. These components are taken in the following ratio, in May. %: clay, for example, grade MKL-1 2-40

 glaze, for example, grades VTR-100 4-20

 aluminum oxide powder

 with a particle size of 40-50 microns, the rest.

 Thus obtained composition is a whitish powder and is intended for the preparation of ceramic products by three-dimensional printing.

 Examples of the preparation of precursor powder compositions and test results of ceramic products prepared using the claimed compositions.

 Example 1

 The composition was prepared as described above. The components were taken in the following ratio, May. %

 clay MKL-1 10

 glaze VTR-100 12

 aluminum oxide powder

 with a particle size of 40-50 microns 78.

 To test the claimed composition, a test sample of a ceramic product was prepared (size 5x5x5 cm). The ceramic product was made by three-dimensional printing on a Z corp 310 printer.

 Indicators of physical characteristics are shown in Table 1.

 Examples 2-9 illustrate the manufacture of ceramic products by three-dimensional printing in the same way as described in example 1, but with different mass ratios of components, as well as the test results of the samples obtained in examples 2-9.

 The data are shown in table 1.

 Example 10 illustrates the physical characteristics of a ceramic product obtained by three-dimensional printing using Stoneware Ceramic Powder, sold under the brand name Tethonite.

The data are shown in table 1. To determine the deformation of the finished product, three ceramic tubes were made using the Z corp 310 printer using the compositions of Examples Nos. 2, 4, and 9.

 Comparison of the obtained products with the image of the original computer model (photo 1) showed that:

 - when the content of the VTR-100 glaze is 15 wt.% (example 2) in the composition, the differences in angles caused by the fire lead are on average 1.6 degrees (photo 2);

 - when the content of the glaze VTR-100 is 21 wt.% (example 4), the differences in the angles caused by the fire lead are

10 degrees or more (photo 3);

 when the content of glaze VTR-100 in the composition is 3 wt.%

(example 9) the amount of glaze is not enough to maintain shape - the product crumbled during firing (photo 4).

 Additionally, the density of the powder was determined in the print chamber on the right side and on the left side after printing, prepared according to example 1 and powder Stoneware Ceramic Powder brand Tethonite (example 10).

 The results are shown in table 2.

 As can be seen from the above data, the density of the powder prepared according to example 1, on the right side in the print chamber is 155% higher, and on the left side - 134% higher than the density of the powder Stoneware Ceramic Powder.

 OPTIMUM EMBODIMENT OF THE SECOND INVENTION

 A binder composition for three-dimensional printing of ceramic products is prepared by mixing glycerol, isopropyl alcohol, PEG-7 (glyceryl cocoate), ethylene glycol and distilled water in a random order.

The components are then mixed for ~ 5 min until complete homogenization. If necessary, give the finished product a certain color to the specified composition additionally add a water-soluble dye.

 These components are taken in the following ratio, wt.%: Glycerin 0, 5-9, 0

 5 isopropyl alcohol 0, 5-9, 0

 PEG-7 (glyceryl cocoate) 0, 3-5.0

 ethylene glycol 5.0-30.0

 distilled water the rest

 If necessary, dye is introduced into the composition in the amount of 0, 5-4, 0 wt.%.

 The resulting composition is a moderately viscous transparent liquid or has the color of the corresponding dye.

 This composition is suitable for creating ceramic products by three-dimensional printing.

 15 Examples of preparation and testing of the composition of the ingredients of a binder for three-dimensional printing of ceramic products.

 Example 1 1. A binder composition was prepared as described above.

The components of the composition were taken in the following ratio, wt.%:

 ethylene glycol 23.2

 20 isopropyl alcohol 0.8

 glycerin 0.5

 PEG-7 (glyceryl cocoate) 2.7

 distilled water 72.8

 To test the claimed composition, we prepared a test 25 sample of a ceramic product (5x5x5 cm in size) containing 80% clay, 10% maltodextrin and 10% binder — the composition prepared according to this example. The ceramic product was made by three-dimensional printing on a Zcorp 310 printer.

After printing and drying, the product had high cleanability, there was no falsy layer. Physical characteristics of the sample: average density 1250 kg / m ³ ,

compressive strength 8.20 kg / cm ² .

 Examples 12-25 illustrate the manufacture and testing of ceramic products manufactured in the same way as described in example 11, but with different mass ratios of the components of the inventive binder.

 The data are shown in table 3.

 As can be seen from the data given in table 3, a decrease in the content of PEG-7 in the composition (Example 16) leads to a deterioration in physical characteristics:

the average density of 10.88 kg / m ³ ,

 compressive strength 6.15 kg / cm.

 The increased content of PEG-7 also leads to deterioration (example 17):

 average density 10.93 kg / m

compressive strength of 6.23 kg / cm ² .

 The same pattern is manifested when the content of glycerol, isopropyl alcohol, ethylene glycol in the composition changes — going beyond the claimed limits (examples 18-23).

 It should be noted that even when going beyond the claimed, (examples 16-23), the physical characteristics of the products prepared using the proposed composition exceed the characteristics of the prototype:

the average density is higher by 239-276 units (kg / m ³ );

compressive strength is higher at 1.93-1.37 units (kg / cm ² ).

 This confirms the effectiveness of the claimed composition as a binder for three-dimensional printing of ceramic products.

 INDUSTRIAL APPLICABILITY

In the factory laboratory, 9 samples of the precursor powder were prepared and tested, as well as 15 samples of the binder. Prototypes made ceramic products by three-dimensional printing using these compositions.

Tests have confirmed the possibility of industrial use of the claimed compositions and their advantages in comparison with known compositions.

Comparative characteristics of the precursor powder,

 obtained in examples 1-10

 Table 1

Powder density in the chamber

 table 2

Сравнительные данные потребительских свойств керамических изделий

Comparative data on consumer properties of ceramic products

Table 3

Claims

CLAIM 1. The composition of the ingredients of the powder is a precursor for the manufacture of ceramic products by three-dimensional printing containing clay and 5 fluff, characterized in that it additionally contains aluminum oxide, and as a fluff - glaze, in the following ratio of these components, May. %:  glaze 4-20  clay 2-40  W aluminum oxide rest  2. The composition according to claim 1, characterized in that it contains aluminum oxide in the form of a powder with a particle size of 40-50 microns, VTR brand glaze - 100, and MKL brand clay - 1.  3. The composition of the ingredients of the binder for three-dimensional printing of 15 ceramic products containing glycerin, ethylene glycol, secondary alcohol and distilled water, characterized in that it additionally contains PEG-7, and as secondary alcohol it contains isopropyl alcohol, in the following ratio of these components, May. %:  20 glycerin 0, 5-9, 0  isopropyl alcohol 0, 5-9, 0  PEG-7 (glyceryl cocoate) 0.3 -5.0  Ethylene Glycol 5.0-30  distilled water the rest  25 4. The composition according to claim 1, characterized in that it additionally contains a dye in an amount of 0.5-4.0 wt.%.