WO2021042442A1 - Precision casting wax and preparation method therefor - Google Patents

Abstract

A precision casting wax and a preparation method therefor. The precision casting wax consists of the following components in mass percentages: 6％-12％ of a polymer matrix, 20%-40% of a tackifying resin, 0.1%-8% of graphene oxide, 35%-45% of paraffin wax, 10%-15% of microcrystalline wax, 1%-5% of candelilla wax, and 1%-3% of polyethylene wax; the preparation method for the precision casting wax comprises the following steps: 1) adding paraffin wax, microcrystalline wax, candelilla wax, and a tackifying resin into a reaction kettle, and heating and stirring same until they are completely dissolved, so as to obtain a basic wax liquid; and 2) adding a polymer matrix, graphene oxide, and pigment into the reaction kettle, heating and stirring same until they are completely melted, and cooling. The precision casting wax has a modest softening point, and high bending strength, thermal conductivity, hardness, and surface finish, and can completely satisfy the size precision requirements and surface quality requirements of a large precision casting which is bulky and complex.

Description

Precision casting wax and preparation method thereof Technical field

The invention relates to a precision casting wax and a preparation method thereof, and belongs to the technical field of precision casting.

Background technique

Precision casting is also called lost wax casting. The product obtained is precise, complex, and close to the final shape of the part. It can be used directly without processing or with little processing. It is a near-net forming process. Compared with the traditional sand casting process, the casting size obtained by precision casting is more accurate and the surface finish is better.

Precision casting wax is an extremely important material in precision casting, and it has a decisive effect on the quality of castings. Precision casting wax needs to meet the following basic requirements: 1) Have a suitable melting temperature range and solidification temperature range, have the thermal expansion rate and shrinkage rate as small as possible, and have stable chemical properties at higher temperatures; 2) Have sufficient strength, hardness, Plasticity and toughness; 3) The viscosity is moderate in the liquid state, the fluidity is good when making the mold, and the ash content is as low as possible.

Although the existing precision casting waxes can meet general precision casting requirements, they cannot meet the dimensional accuracy requirements and surface quality requirements of thick and complex large precision castings. Therefore, it is necessary to develop new precision casting wax products. Graphene oxide is the oxide of graphene. Oxidation makes it more oxygen-containing functional groups. It is more active than graphene and can be easily modified by the reaction of oxygen-containing functional groups. Graphene oxide has excellent thermal conductivity and mechanical properties, and its use in the field of precision casting is expected to develop a more excellent precision casting wax product.

Summary of the invention

The purpose of the present invention is to provide a precision casting wax and a preparation method thereof.

The technical scheme adopted by the present invention is:

A precision casting wax consisting of the following components by mass percentage:

Polymer matrix: 6% to 12%;

Tackifying resin: 20% to 40%;

Graphene oxide: 0.1%～8%;

Paraffin: 35% ~ 45%;

Microcrystalline wax: 10%-15%;

Candelilla wax: 1%～5%;

Polyethylene wax: 1% to 3%.

Preferably, a precision casting wax is composed of the following components by mass percentage:

Polymer matrix: 6% to 8%;

Tackifying resin: 25%～30%;

Graphene oxide: 2%～6%;

Paraffin: 40%-45%;

Microcrystalline wax: 13%-15%;

Candelilla wax: 2%～4%;

Polyethylene wax: 1% to 2%.

Preferably, the polymer matrix is at least one of ethylene-octene copolymer, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, and polystyrene.

Preferably, the softening point of the tackifying resin is 90-105°C.

Further preferably, the tackifying resin is at least one of C5 petroleum resin, C5 hydrogenated petroleum resin, rosin glyceride, and hydrogenated rosin.

Preferably, the graphene oxide has a 1-5 layer lamella structure, the lateral dimension of the lamella is 1-10 μm, and the oxygen content is 30wt%-50wt%.

Preferably, the paraffin wax is 58# fully refined paraffin, 58# semi-refined paraffin, 60# fully refined paraffin, 60# semi-refined paraffin, 62# fully refined paraffin, 62# semi-refined paraffin, 64# fully refined paraffin, 64 #半 Refining Paraffin, 66# Full Refined Paraffin, 66# Semi-refined Paraffin at least one.

Preferably, the microcrystalline wax is at least one of 70# microcrystalline wax, 75# microcrystalline wax, and 80# microcrystalline wax.

Preferably, the melting point of the candelilla wax is 75-85°C and the acidity value is 10-15 mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add paraffin wax, microcrystalline wax, candelilla wax and tackifying resin into the reaction kettle, heat and stir to completely dissolve, to obtain the basic wax liquid;

2) The polymer matrix, graphene oxide and polyethylene wax are added to the reaction kettle, heated and stirred until completely melted, and cooled to obtain precision casting wax.

Preferably, the heating temperature in step 1) is 100-120°C.

Preferably, the heating temperature in step 2) is 125-140°C.

The beneficial effects of the present invention are: the precision casting wax of the present invention has moderate softening point, high bending strength, high thermal conductivity, high hardness, and high surface finish, and can fully meet the dimensional accuracy requirements and surface of large and complex precision castings. Quality requirements and broad market application prospects.

Description of the drawings

Figure 1 shows the thermal conductivity-graphene oxide content relationship curve.

Figure 2 shows the relationship curve between flexural strength and graphene oxide content.

Figure 3 shows the relationship between viscosity and graphene oxide content.

detailed description

The present invention will be further explained and illustrated below in conjunction with specific embodiments.

Example 1:

A precision casting wax whose composition is shown in the table below:

Table 1 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	25
Rosin glyceride	15
Graphene oxide	0.1
62# Fully refined paraffin wax	20
64# fully refined paraffin	14.9
70#microcrystalline wax	11
Candelilla wax	5
Polyethylene wax	3

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 62# fully refined paraffin wax, 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax, C5 hydrogenated petroleum resin and rosin glyceride into the reaction kettle, heat to 120°C, stir for 30 minutes to obtain the basic wax liquid;

2) Add ethylene-vinyl acetate copolymer, graphene oxide and polyethylene wax to the reactor, heat up to 140°C, stir for 1.5h, and drop the temperature to about 100°C until the bubbles on the surface of the solution disappear completely, and cool to obtain precision casting wax .

Example 2:

A precision casting wax whose composition is shown in the table below:

Table 2 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	30
Hydrogenated rosin	5
Graphene oxide	0.5
62# Fully refined paraffin wax	20
64# fully refined paraffin	20
70#microcrystalline wax	12
Candelilla wax	4.5
Polyethylene wax	2

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 62# fully refined paraffin wax, 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax, C5 hydrogenated petroleum resin and hydrogenated rosin to the reaction kettle, heat to 120°C, stir for 30 minutes, and obtain the basic wax liquid ；

2) Put ethylene-vinyl acetate copolymer, graphene oxide and polyethylene wax into the reaction kettle, heat up to 140℃, stir for 1.5h, and lower the temperature to about 100℃ until the bubbles on the surface of the solution disappear completely, and cool to obtain precision casting wax .

Example 3:

A precision casting wax whose composition is shown in the table below:

Table 3 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
Polypropylene	2
C5 Hydrogenated Petroleum Resin	25
Rosin glyceride	9
Graphene oxide	1
62# Fully refined paraffin wax	38
70#microcrystalline wax	12

Candelilla wax	5
Polyethylene wax	2

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 62# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax, C5 hydrogenated petroleum resin and rosin glyceride into the reaction kettle, heat to 115°C and stir for 30 minutes to obtain the basic wax liquid;

2) Put ethylene-vinyl acetate copolymer, polypropylene, graphene oxide and polyethylene wax into the reaction kettle, heat up to 135℃, stir for 2h, and drop the temperature to about 100℃ until the bubbles on the surface of the solution disappear completely. Cool down to obtain precision Casting wax.

Example 4:

A precision casting wax whose composition is shown in the table below:

Table 4 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	8
Ethylene-octene copolymer	2
C5 Hydrogenated Petroleum Resin	32
Graphene oxide	1.5
62# Fully refined paraffin wax	14
64# fully refined paraffin	25
70#microcrystalline wax	13
Candelilla wax	3
Polyethylene wax	1.5

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 62# fully refined paraffin wax, 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 115°C, stir for 30 minutes, and obtain the basic wax liquid;

2) Put ethylene-vinyl acetate copolymer, ethylene-octene copolymer, graphene oxide and polyethylene wax into the reaction kettle, heat up to 135℃, stir for 2.5h, and drop the temperature to about 100℃ until the bubbles on the surface of the solution disappear completely , Cool, get precision casting wax.

Example 5:

A precision casting wax whose composition is shown in the table below:

Table 5 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	7
Ethylene-octene copolymer	1
C5 Hydrogenated Petroleum Resin	30
Graphene oxide	2
62# Fully refined paraffin wax	10
64# fully refined paraffin	30
70#microcrystalline wax	14
Candelilla wax	4
Polyethylene wax	2

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 62# fully refined paraffin wax, 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 115°C, stir for 30 minutes, and obtain the basic wax liquid;

2) Add ethylene-vinyl acetate copolymer, ethylene-octene copolymer, graphene oxide and polyethylene wax to the reaction kettle, heat up to 135°C, stir for 2h, and lower the temperature to about 100°C until the bubbles on the surface of the solution disappear completely. After cooling, precision casting wax is obtained.

Example 6:

A precision casting wax whose composition is shown in the table below:

Table 6 Composition table of a kind of precision casting wax

raw material

Mass percentage (%)

Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	30
Graphene oxide	4
64# fully refined paraffin	40
70#microcrystalline wax	15
Candelilla wax	3
Polyethylene wax	2

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 115°C and stir for 30 minutes to obtain the basic wax liquid;

2) Put ethylene-vinyl acetate copolymer, graphene oxide and polyethylene wax into the reactor, heat up to 135°C, stir for 1.5h, and drop the temperature to about 100°C until the bubbles on the surface of the solution disappear completely. Cool down to obtain precision casting wax .

Example 7:

A precision casting wax whose composition is shown in the table below:

Table 7 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6.5
Ethylene-octene copolymer	1.5
C5 Hydrogenated Petroleum Resin	25
Graphene oxide	6
64# fully refined paraffin	35
66# Fully refined paraffin wax	10
70#microcrystalline wax	13
Candelilla wax	2
Polyethylene wax	1

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 64# fully refined paraffin wax, 66# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 110°C and stir for 30 minutes to obtain the basic wax liquid;

2) Add ethylene-vinyl acetate copolymer, ethylene-octene copolymer, graphene oxide and polyethylene wax to the reaction kettle, heat up to 130°C, stir for 2h, and lower the temperature to about 100°C until the bubbles on the surface of the solution disappear completely. After cooling, precision casting wax is obtained.

Example 8:

A precision casting wax whose composition is shown in the table below:

Table 8 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	20
Graphene oxide	8
64# fully refined paraffin	30
66# Fully refined paraffin wax	15
70#microcrystalline wax	15
Candelilla wax	5
Polyethylene wax	1

Note:

Graphene oxide: It has a 1-5 layer structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%-50wt%;

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 64# fully refined paraffin wax, 66# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 110°C and stir for 30 minutes to obtain the basic wax liquid;

2) Put the ethylene-vinyl acetate copolymer, graphene oxide and polyethylene wax into the reaction kettle, heat up to 125℃, stir for 1.5h, and lower the temperature to about 100℃ until the bubbles on the surface of the solution disappear completely, and cool down to obtain precision casting wax .

Comparative example 1:

A precision casting wax whose composition is shown in the table below:

Table 9 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	40
64# fully refined paraffin	35
70#microcrystalline wax	11
Candelilla wax	5
Polyethylene wax	3

Note:

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 64# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 120°C and stir for 30 minutes to obtain the basic wax liquid;

2) Put the ethylene-vinyl acetate copolymer and polyethylene wax into the reaction kettle, raise the temperature to 140°C, stir for 1.5h, and lower the temperature to about 100°C until the bubbles on the surface of the solution disappear completely, and cool to obtain the precision casting wax.

Comparative example 2:

A precision casting wax whose composition is shown in the table below:

Table 10 Composition table of a kind of precision casting wax

raw material	Mass percentage (%)
Ethylene-vinyl acetate copolymer	6
C5 Hydrogenated Petroleum Resin	20
oxidised graphite	8
64# fully refined paraffin	30
66# Fully refined paraffin wax	15
70#microcrystalline wax	15
Candelilla wax	5
Polyethylene wax	1

Note:

Candelilla wax: melting point is 75～85℃, acidity value is 10～15mgKOH/g.

The preparation method of the above-mentioned precision casting wax includes the following steps:

1) Add 64# fully refined paraffin wax, 66# fully refined paraffin wax, 70# microcrystalline wax, candelilla wax and C5 hydrogenated petroleum resin into the reaction kettle, heat to 110°C and stir for 30 minutes to obtain the basic wax liquid;

2) Put the ethylene-vinyl acetate copolymer, graphite oxide and polyethylene wax into the reaction kettle, raise the temperature to 125°C, stir for 1.5h, and drop the temperature to about 100°C until the bubbles on the surface of the solution completely disappear, and cool to obtain the precision casting wax.

Test case:

1) Perform performance tests on the precision casting waxes of Examples 1-8 and Comparative Examples 1-2. The test results are shown in the following table:

Table 11 Performance test results of the precision casting waxes of Examples 1-8 and Comparative Examples 1-2

Note:

Softening point: GB/T 4507-1984; penetration: GB/T 14235.5-1993; viscosity: GB/T 14235.8-1993; surface roughness: JB/T 7976-2010; bending strength: GB/T 14235.2- 1993; Thermal conductivity: ASTM C518-2010.

It can be seen from Table 11 that compared with the precision casting waxes of Comparative Examples 1 to 2, the thermal conductivity of the precision casting waxes of Examples 1 to 8 is greatly improved, and the hardness, surface finish and bending strength are all improved, and the comprehensive performance is very high. Excellent.

2) By adjusting the graphene oxide content in the precision casting wax formula of the present invention, the thermal conductivity-graphene oxide content relationship curve obtained by the test is shown in FIG. 1.

It can be seen from Figure 1 that the thermal conductivity of precision casting wax increases with the increase of graphene oxide content. When the content of graphene oxide reaches 8%, the thermal conductivity of precision casting wax no longer increases. At this time, the thermal conductivity of precision casting wax The thermal conductivity is increased by more than 30 times compared with not adding graphene oxide.

The reason is that the graphene oxide sheet layer has a large aspect ratio, which can form an ordered agglomeration end to end in the precision casting wax matrix material, so that the heat flow is rapidly transferred in the ordered grid structure formed by the graphene oxide, and then Can improve the thermal conductivity of the composite.

3) By adjusting the graphene oxide content in the precision casting wax formula of the present invention, the measured bending strength-graphene oxide content relationship curve is shown in FIG. 2.

It can be seen from Figure 2 that the bending strength of the precision casting wax first increases and then decreases with the increase of the graphene oxide content, and finally the bending strength of the precision casting wax tends to be stable.

The reason is that the mechanical properties of graphene oxide itself are much higher than the other components of the precision casting wax. When the content of graphene oxide is low, the dispersion in the precision casting wax is better, and there is a strong interface between the graphene oxide and the resin group. The effect enhances the strength of the precision casting wax, but when the content of graphene oxide is relatively high, the graphene oxide and the resin are likely to form agglomerates, forming a relatively weak bonding interface, resulting in a decrease in the mechanical properties of the precision casting wax.

4) By adjusting the graphene oxide content in the precision casting wax formula of the present invention, the measured viscosity-graphene oxide content relationship curve is shown in FIG. 3.

It can be seen from Figure 3 that the viscosity of the precision casting wax decreases with the increase of the graphene oxide content. When the content of graphene oxide reaches 6%, the viscosity of the precision casting wax no longer decreases.

The reason is that there are a large number of oxygen-containing groups in graphene oxide, and the oxygen-containing groups will react with the short molecular chains of the polymer matrix in the precision casting wax, reducing the degree of polymerization of the polymer and causing intermolecular entanglement. The decrease of the effect leads to the increase of melt fluidity, thereby reducing the viscosity of the precision casting wax. However, as the content of graphene oxide gradually increases, the agglomeration between graphene oxide and the polymer matrix increases, so that it can no longer interact with the polymer. The short molecular chain of the matrix reacts, and the viscosity of the precision casting wax tends to be stable.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, etc. made without departing from the spirit and principle of the present invention Simplified, all should be equivalent replacement methods, and they are all included in the protection scope of the present invention.

Claims (10)

1. A precision casting wax, characterized in that it is composed of the following mass percentage components:

   Polymer matrix: 6% to 12%;

   Tackifying resin: 20% to 40%;

   Graphene oxide: 0.1%～8%;

   Paraffin: 35% ~ 45%;

   Microcrystalline wax: 10%-15%;

   Candelilla wax: 1%～5%;

   Polyethylene wax: 1% to 3%.
2. The precision casting wax according to claim 1, wherein the polymer matrix is at least one of ethylene-octene copolymer, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, and polystyrene .
3. The precision casting wax according to claim 1, wherein the softening point of the tackifying resin is 90-105°C.
4. The precision casting wax according to claim 3, wherein the tackifying resin is at least one of C5 petroleum resin, C5 hydrogenated petroleum resin, rosin glyceride, and hydrogenated rosin.
5. The precision casting wax according to any one of claims 1 to 4, characterized in that: the graphene oxide has a 1-5 layer lamella structure, the lateral dimension of the lamella is 1-10μm, and the oxygen content is 30wt%~ 50wt%.
6. The precision casting wax according to any one of claims 1 to 4, wherein the paraffin wax is 58# fully refined paraffin, 58# semi-refined paraffin, 60# fully refined paraffin, 60# semi-refined paraffin, 62 #全 Refining Paraffin, 62# Semi-refined Paraffin, 64# Full Refined Paraffin, 64# Semi-refined Paraffin, 66# Full Refined Paraffin, 66# Semi-refined Paraffin.
7. The precision casting wax according to any one of claims 1 to 4, wherein the microcrystalline wax is at least one of 70# microcrystalline wax, 75# microcrystalline wax, and 80# microcrystalline wax.
8. The precision casting wax according to any one of claims 1 to 4, wherein the candelilla wax has a melting point of 75-85°C and an acidity value of 10-15 mgKOH/g.
9. The method for preparing precision casting wax according to any one of claims 1 to 8, characterized in that it comprises the following steps:

   1) Add paraffin wax, microcrystalline wax, candelilla wax and tackifying resin into the reaction kettle, heat and stir to completely dissolve, to obtain the basic wax liquid;

   2) The polymer matrix, graphene oxide and polyethylene wax are added to the reaction kettle, heated and stirred until completely melted, and cooled to obtain precision casting wax.
10. The preparation method according to claim 9, wherein the heating temperature in step 1) is 100-120°C; the heating temperature in step 2) is 125-140°C.

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