Styrene microspheres and preparation thereof, and filling type wax material and preparation thereof

Abstract

The invention belongs to the technical field of filling wax, and provides styrene microspheres and preparation thereof, and a filling type wax material and preparation thereof. According to the preparation method disclosed by the invention, styrene is taken as a first monomer, one or more of octocapric acid propylene glycol ester, neocapric acid vinyl ester and propylene glycol dicaprylate are taken as a second monomer, and the styrene microspheres are prepared through an emulsion polymerization method. By using the second monomer, the alkyl side chain of the styrene microsphere is increased, so that the dispersity of the styrene microsphere in molten casting wax is improved. When the prepared styrene microspheres are used as a filler and are filled into casting wax, the rigidity of the casting wax can be enhanced, the bending strength, the vicat softening point and the surface flatness of the casting wax can be improved, and the volume shrinkage rate of the casting wax after curing can also be reduced. The invention further provides a preparation method of the filling type wax material according to the technical scheme, the preparation method provided by the invention is simple and convenient to operate, and the comprehensive performance of casting wax can be greatly improved.

Description

Technical Field

[0001] This invention relates to the field of filled wax technology, and more particularly to a styrene microsphere and its preparation, and a filled wax material and its preparation. Background Technology

[0002] Investment casting, also known as lost-wax casting or precision casting, involves preparing a precisely dimensionally accurate fusible model from fusible materials such as wax. A refractory coating is then applied to the wax model, followed by drying, hardening, and high-temperature firing to create a refractory shell. Liquid metal is then poured into the shell, and after cooling, a metal casting is obtained. Investment casting technology is of great significance to the development of aerospace, automotive, and shipbuilding industries. During the casting process, the wax model needs to possess good mechanical strength and excellent dimensional stability to facilitate assembly, handling, and the production of high-quality castings. However, excessive shrinkage of the wax can lead to dimensional instability in the wax model, resulting in poor dimensional accuracy of the final casting. Therefore, organic fillers can be added to optimize and improve the performance of the casting wax. Chinese patent CN118109058A discloses a filled wax and its preparation method, including components such as paraffin wax, microcrystalline wax, resin, heat stabilizer, chitosan, stearic acid, initiator, maleic anhydride, and filler (any one of talc, cellulose powder and barium sulfate). The shrinkage of the prepared filled wax after curing needs to be further reduced; and the preparation method is complicated. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide styrene microspheres and their preparation, as well as a filled wax and its preparation. The styrene microspheres provided by this invention, when used in filled waxes, improve the dimensional stability of the filled waxes.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing styrene microspheres, comprising the following steps:

[0006] The crosslinking agent, initiator, and organic monomer are mixed to obtain the oil phase;

[0007] The emulsifier and water are mixed to obtain an aqueous phase;

[0008] The oil phase and the aqueous phase are mixed and then emulsified and polymerized sequentially to obtain the styrene microspheres.

[0009] The organic monomer includes a first monomer and a second monomer;

[0010] The first monomer is styrene;

[0011] The second monomer includes one or more of propylene glycol octanoate, vinyl neodecanoate, and propylene glycol dioctanoate.

[0012] Preferably, the mass ratio of the first monomer to the second monomer is 1:1, and the mass fraction of the organic monomer in the oil phase is 60-90%.

[0013] Preferably, the crosslinking agent comprises one or more of 1,4-butanediol dimethacrylate, pentaerythritol triacrylate, and ethylene glycol dimethacrylate; the weight ratio of the crosslinking agent to the organic monomer is 5-20:25-100;

[0014] The initiator includes benzoyl peroxide and / or azobisisobutyronitrile; the weight ratio of the initiator to the organic monomer is 1-8:25-100.

[0015] Preferably, the emulsifier comprises one or more of cetyltrimethylammonium bromide, polyvinyl alcohol, hydroxypropyl methylcellulose, OP-10, and Span 80; the mass fraction of the emulsifier in the aqueous phase is 0.1-0.5%.

[0016] Preferably, the weight ratio of the aqueous phase to the oil phase is 5-25:1-8.

[0017] Preferably, the emulsification temperature is 30–60°C, the time is 20–50 min, the emulsification is carried out under stirring conditions, and the stirring speed is 600–1000 rpm.

[0018] Preferably, the polymerization temperature is 50–100°C, the time is 5–8 hours, and the polymerization is carried out under stirring conditions, with the stirring speed being 600–1000 rpm.

[0019] The present invention also provides styrene microspheres prepared by the preparation method described in the above technical solution.

[0020] The present invention also provides a filled wax material, comprising casting wax and filler; the casting wax comprises the following components in weight percentage:

[0021] Paraffin wax 20-40%, microcrystalline wax 5-25%, polyethylene wax 3-20%, resin 10-30%, dispersant 4-18%;

[0022] The mass of the filler is 1 to 30% of the mass of the casting wax;

[0023] The filler is the styrene microspheres described in the above technical solution.

[0024] The present invention also provides a method for preparing the filler wax described in the above technical solution, comprising the following steps:

[0025] Paraffin wax, microcrystalline wax, polyethylene wax, resin, and dispersant are melt-mixed to obtain molten casting wax;

[0026] The molten casting wax and filler are mixed and then solidified to obtain the filled wax material.

[0027] This invention provides a method for preparing styrene microspheres.

[0028] The preparation method of this invention uses styrene as the first monomer and one or more of propylene glycol octanoate, vinyl neodecanoate, and propylene glycol dioctanoate as the second monomer. Styrene microspheres are prepared by emulsion polymerization, and the resulting styrene microspheres are a white powder. The use of the second monomer increases the alkyl side chains of the styrene microspheres, thereby improving their dispersibility in molten casting wax. The styrene microspheres prepared by this invention can fill and strengthen the properties of casting wax, increasing the density and rigidity of the filled wax, thereby improving the flexural strength, Vicat softening point, and surface smoothness of the filled wax, and reducing the volume shrinkage rate after curing. Therefore, the styrene microspheres prepared by this invention improve the overall performance and enhance the dimensional stability of the filled wax. Furthermore, with the increase of the styrene microsphere filling amount, the overall performance of the filled wax is also significantly improved.

[0029] The present invention also provides a method for preparing a filler wax. The preparation method provided by the present invention is simple to operate and can greatly improve the overall performance of casting wax. Attached Figure Description

[0030] Figure 1 Scanning electron microscope image of the styrene microspheres prepared in Example 1;

[0031] Figure 2 The bending strength of the filled casting waxes in Examples 1-5 after filling with different contents of styrene microspheres;

[0032] Figure 3 The Vicat softening points of the filled casting waxes in Examples 1-5 after being filled with different contents of styrene microspheres;

[0033] Figure 4 The volume shrinkage rate of the filled casting wax after filling with different contents of styrene microspheres in Examples 1-5;

[0034] Figure 5 This study describes the dispersion and settling of styrene microspheres grafted with different amounts of neodecanoic acid ester, glass microspheres, and talc powder in molten casting wax, as well as in Comparative Examples 1-5 and Example 1. Detailed Implementation

[0035] This invention provides a method for preparing styrene microspheres, comprising the following steps:

[0036] The crosslinking agent, initiator, and organic monomer are mixed to obtain the oil phase;

[0037] The emulsifier and water are mixed to obtain an aqueous phase;

[0038] The oil phase and the aqueous phase are mixed and then emulsified and polymerized sequentially to obtain the styrene microspheres.

[0039] The organic monomer includes a first monomer and a second monomer;

[0040] The first monomer is styrene;

[0041] The second monomer includes one or more of propylene glycol octanoate, vinyl neodecanoate, and propylene glycol dioctanoate.

[0042] Unless otherwise specified, the raw materials used in this invention are preferably commercially available products.

[0043] This invention mixes a crosslinking agent, an initiator, and an organic monomer to obtain an oil phase.

[0044] In this invention, the crosslinking agent preferably includes one or more of 1,4-butanediol dimethacrylate, pentaerythritol triacrylate, and ethylene glycol dimethacrylate, and more preferably pentaerythritol triacrylate.

[0045] In this invention, the initiator preferably includes benzoyl peroxide and / or azobisisobutyronitrile, and more preferably azobisisobutyronitrile.

[0046] In this invention, the organic monomer comprises a first monomer and a second monomer. In this invention, the first monomer is styrene. In this invention, the second monomer comprises one or more of propylene glycol octanoate, vinyl neodecanoate, and propylene glycol dioctanoate, preferably vinyl neodecanoate. In this invention, the mass ratio of the first monomer to the second monomer is preferably 1:1.

[0047] In this invention, the weight ratio of the initiator to the organic monomer is preferably 1–8:25–100, and more preferably 2:25. In this invention, the weight ratio of the crosslinking agent to the organic monomer is preferably 5–20:25–100, and more preferably 9:50.

[0048] In this invention, the dissolution temperature is preferably room temperature, i.e., neither additional heating nor additional cooling is required, and the dissolution is preferably carried out under stirring conditions.

[0049] This invention mixes an emulsifier and water to obtain an aqueous phase.

[0050] In this invention, the emulsifier preferably includes one or more of hexadecyltrimethylammonium bromide, polyvinyl alcohol, hydroxypropyl methylcellulose, OP-10, and Span 80, more preferably hydroxypropyl methylcellulose. In this invention, the mass fraction of the emulsifier in the aqueous phase is preferably 0.1% to 0.5%, specifically preferably 0.1%, 0.16%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0051] After obtaining the oil phase and the aqueous phase, the present invention mixes the oil phase and the aqueous phase, and then emulsifies and polymerizes them sequentially to obtain the styrene microspheres.

[0052] In this invention, the weight ratio of the aqueous phase to the oil phase is preferably 5-25:1-8, and more preferably 600:63.

[0053] In this invention, the emulsification temperature is preferably 30-60°C, specifically 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C; the emulsification time is preferably 20-50 min, specifically 20 min, 30 min, 40 min, or 50 min; the emulsification is preferably carried out under stirring conditions, and the stirring speed is preferably 600-1000 rpm, specifically 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm.

[0054] In this invention, the polymerization temperature is preferably 50–100°C, more preferably 60–90°C, and specifically preferably 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C; the time is preferably 5–8 hours, and specifically preferably 5 hours, 6 hours, 7 hours, or 8 hours; the polymerization is preferably carried out under stirring conditions, and the stirring speed is preferably the same as the emulsification speed, which will not be elaborated here.

[0055] In this invention, the polymerization temperature is preferably higher than the emulsification temperature.

[0056] After the polymerization is completed, the present invention preferably further includes: cooling the obtained polymerization liquid to room temperature, performing solid-liquid separation, and drying the collected solid to obtain the styrene microspheres. In the present invention, the solid-liquid separation is preferably performed by centrifugation. In the present invention, the drying temperature is preferably 40–60°C, and the drying is preferably carried out in an oven.

[0057] This invention also provides styrene microspheres prepared by the method described above. In this invention, the particle size of the styrene microspheres is preferably 30–50 μm. In this invention, the styrene microspheres are preferably a white powder.

[0058] The present invention also provides a filled wax material, comprising casting wax and filler; the casting wax comprises the following components in weight percentage:

[0059] Paraffin wax 20-40%, microcrystalline wax 5-25%, polyethylene wax 3-20%, resin 10-30%, dispersant 4-18%;

[0060] The mass of the filler is 1 to 30% of the mass of the casting wax;

[0061] The filler is the styrene microspheres described in the above technical solution.

[0062] The filler wax provided by this invention includes casting wax.

[0063] In this invention, the casting wax comprises 20-40% paraffin wax by weight percentage, preferably 20%, 25%, 30%, 35%, 38% or 40%.

[0064] In this invention, the casting wax comprises 5-25% microcrystalline wax by weight percentage, preferably 5%, 10%, 11%, 15%, 20% or 25%.

[0065] In this invention, the casting wax comprises 3-20% polyethylene wax by weight percentage, preferably 3%, 5%, 8%, 10%, 12%, 15%, 18% or 20%.

[0066] In this invention, the casting wax comprises 10-30% resin by weight, preferably 10%, 15%, 20%, 25%, or 30%. In this invention, the resin is preferably one or more of rosin resin, petroleum resin, and phenolic resin, more preferably petroleum resin.

[0067] In this invention, the casting wax comprises 4-18% dispersant by weight, specifically preferably 4%, 6%, 8%, 10%, 12%, 13%, 14%, 16%, or 18%. In this invention, the dispersant is selected from one or more of plastic dispersants, sodium lignosulfonate, and stearic acid, more preferably plastic dispersants. Specifically, the plastic dispersant is preferably one or more of Honeywell's AC540A, AC400A, and AC6A.

[0068] The filled wax material provided by this invention includes a filler, which is the styrene microspheres described in the above-mentioned technical solution. In this invention, the mass of the filler is 1% to 30% of the mass of the casting wax, preferably 5%, 10%, 15%, 20%, 25%, or 30%.

[0069] The present invention also provides a method for preparing the filler wax described in the above technical solution, comprising the following steps:

[0070] Paraffin wax, microcrystalline wax, polyethylene wax, resin, and dispersant are melt-mixed to obtain molten casting wax;

[0071] The molten casting wax and filler are mixed and then solidified to obtain the filled wax material.

[0072] This invention involves melting and mixing paraffin wax, microcrystalline wax, polyethylene wax, resin, and dispersant to obtain molten casting wax.

[0073] In this invention, the melting and mixing temperature is preferably 80-150°C, specifically 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 145°C or 150°C; the time is preferably 1-4 hours, specifically 1 hour, 2 hours, 3 hours or 4 hours.

[0074] After obtaining the molten casting wax, the present invention mixes the molten casting wax with a filler and solidifies it to obtain the filled wax material.

[0075] In this invention, the mixing temperature of the molten casting wax and the filler is preferably 80–125°C, more preferably 90–120°C, and specifically preferably 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or 125°C; the mixing time is preferably 20–60 min, more preferably 20–40 min, and specifically preferably 20 min, 30 min, 40 min, 50 min, or 60 min; the mixing of the molten casting wax and the filler is preferably carried out under magnetic stirring conditions. This invention does not have special requirements for the magnetic stirring, and any magnetic stirring method well known to those skilled in the art can be used.

[0076] In this invention, the curing temperature is preferably room temperature, that is, neither additional heating nor additional cooling is required; the curing time is preferably 20 to 30 hours, specifically 20 hours, 22 hours, 24 hours, 26 hours, 28 hours or 30 hours.

[0077] The following detailed descriptions of the styrene microspheres and their preparation, as well as the filled wax and its preparation, provided by the present invention, are in conjunction with specific examples. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0078] Example 1

[0079] (1) Preparation of styrene microspheres

[0080] Pentaerythritol triacrylate, azobisisobutyronitrile, and organic monomers (including styrene and vinyl decanoate, with vinyl decanoate comprising 50% by weight of the organic monomers, i.e., a mass ratio of styrene to vinyl decanoate of 1:1) were stirred and mixed at room temperature to obtain an oil phase; the mass ratio of pentaerythritol triacrylate to organic monomers was 9:50, and the mass ratio of azobisisobutyronitrile to organic monomers was 2:25.

[0081] Hydroxypropyl methylcellulose and water were mixed to obtain an aqueous phase with a mass fraction of 0.16%.

[0082] The aqueous phase and oil phase were mixed at a weight ratio of 600:63 and emulsified at 800 rpm and 55°C for 40 min to form an emulsion. The stirring speed was kept constant, and the emulsion was heated and stirred at 90°C for 6 h. After cooling to room temperature, the emulsion was centrifuged and dried to obtain styrene microspheres.

[0083] (2) Preparation of filler wax based on styrene microspheres

[0084] By weight percentage, 38% paraffin wax, 11% microcrystalline wax, 8% polyethylene wax, 30% resin (specifically petroleum resin) and 13% dispersant (specifically AC540A) were melt-mixed at 145°C for 4 hours to obtain molten casting wax.

[0085] Molten casting wax and styrene microspheres were stirred and mixed at 125°C for 30 min and cured at room temperature for 24 h to obtain a filled wax material, wherein the mass of the styrene microspheres was 5% of the mass of the molten casting wax.

[0086] Examples 2-5

[0087] The difference between Examples 2-5 and Example 1 lies in the content of styrene microspheres used as fillers; the other operations are the same. In Examples 2-5, the filling amounts of styrene microspheres were 0%, 10%, 20%, and 30% of the mass of the molten casting wax, respectively.

[0088] Comparative Examples 1-3

[0089] The difference between Comparative Examples 1-3 and Example 1 is that the weight percentage of vinyl decanoate in the organic monomers during the preparation of styrene microspheres is different, namely 0% (corresponding to all organic monomers being styrene), 10% (corresponding to a mass ratio of vinyl decanoate to styrene of 1:9), and 20% (corresponding to a mass ratio of vinyl decanoate to styrene of 2:8). The other operations are the same as in Example 1.

[0090] Comparative Example 4

[0091] The difference from Example 1 is that the styrene microspheres are replaced with glass microspheres.

[0092] Comparative Example 5

[0093] The difference from Example 1 is that the styrene microspheres are replaced with talc.

[0094] Performance Test 1

[0095] The filled wax materials obtained in the examples and comparative examples were prepared into samples of 20mm × 40mm × 6mm, and the flexural strength of the samples was tested using a universal testing machine. The test standard for flexural strength is GB / T14235.2-2018.

[0096] Performance Test 2

[0097] The filled waxes obtained in the examples and comparative examples were prepared into samples of 20mm×20mm×6mm, and the Vicat softening point of the filled waxes was determined using a Vicat softening point tester.

[0098] Performance Test 3

[0099] The molten styrene microsphere-based filled wax obtained in the examples and comparative examples was poured into a 100mL beaker to the 50mL mark. After the filled wax solidified at room temperature, deionized water was added to the beaker to the 50mL mark. The shrinkage rate of the filled wax was calculated based on the volume of water added.

[0100] Figure 1 The image shows a scanning electron microscope (SEM) image of the styrene microspheres prepared in Example 1. Figure 1 It is known that the particle size of styrene microspheres is approximately 30–50 μm.

[0101] Figure 2 The flexural strength of the filled casting waxes in Examples 1-5, after being filled with different contents of styrene microspheres, was determined by... Figure 2 It is known that the flexural strength of the filled casting wax is improved after filling with styrene microspheres, and the flexural strength increases with the increase of styrene microsphere content. Therefore, the styrene microsphere-based filled wax of the present invention can enhance the rigidity of the casting wax, thereby reducing the loss of casting wax due to breakage during transportation.

[0102] Figure 3 The Vicat softening point of the filled casting waxes in Examples 1-5, after being filled with different contents of styrene microspheres, is determined by... Figure 3 It can be seen that the Vicat softening point of the filled casting wax is increased after filling with styrene microspheres, and the Vicat softening point increases with the increase of styrene microsphere filling content, thereby improving the thermal stability of the filled casting wax.

[0103] Figure 4 The volume shrinkage rate of the filled casting waxes in Examples 1-5, after being filled with different contents of styrene microspheres, is determined by... Figure 4It is known that the volume shrinkage rate of filled casting wax decreases after filling with styrene microspheres, and the volume shrinkage rate gradually decreases with increasing styrene microsphere content. Therefore, filling with styrene microspheres can increase the density of filled casting wax, thereby increasing the dimensional stability of filled casting wax.

[0104] Figure 5 To compare the dispersion and settling of styrene microspheres grafted with different contents of vinyl decanoate in Examples 1-5 and Example 1, as well as glass microspheres and talc powder in molten casting wax, the following methods were used: Figure 5 It can be seen that styrene microspheres have good compatibility with molten casting wax, and after grafting with vinyl neodecanoate, the dispersibility of the microspheres in the casting wax is significantly improved, and the sedimentation rate is significantly slowed down. In contrast, glass microspheres and talc have poor compatibility with molten casting wax, agglomerate, and settle to the bottom of the beaker in a viscous state, making them unsuitable as filler wax materials.

[0105] Depend on Figure 5 It can be seen that the styrene microspheres obtained in Comparative Examples 1-3 settled relatively quickly in molten casting wax. Their dispersibility was also slightly worse than that of Example 1, exhibiting a slightly grainy texture. After curing at room temperature, unevenness appeared, making it impossible to prepare samples for testing flexural strength, Vicat softening point, and linear shrinkage. Comparative Examples 4 and 5 were incompatible in molten casting wax, agglomerated, and could not be tested. The performance test results of the samples obtained in Examples 1-5 are shown in Table 1.

[0106] Table 1 Performance test results of samples obtained in Examples 1-5

[0107]

[0108] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing styrene microspheres, characterized in that, Includes the following steps: The crosslinking agent, initiator, and organic monomer are mixed to obtain the oil phase; The emulsifier and water are mixed to obtain an aqueous phase; The oil phase and the aqueous phase are mixed and then emulsified and polymerized sequentially to obtain the styrene microspheres. The organic monomer includes a first monomer and a second monomer; The first monomer is styrene; The second monomer includes one or more of propylene glycol octanoate, vinyl neodecanoate, and propylene glycol dioctanoate.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the first monomer to the second monomer is 1:

1.

3. The preparation method according to claim 1, characterized in that, The crosslinking agent includes one or more of 1,4-butanediol dimethacrylate, pentaerythritol triacrylate, and ethylene glycol dimethacrylate; the weight ratio of the crosslinking agent to the organic monomer is 5-20:25-100. The initiator includes benzoyl peroxide and / or azobisisobutyronitrile; the weight ratio of the initiator to the organic monomer is 1-8:25-100.

4. The preparation method according to claim 1, characterized in that, The emulsifier includes one or more of cetyltrimethylammonium bromide, polyvinyl alcohol, hydroxypropyl methylcellulose, OP-10, and Span 80; the mass fraction of the emulsifier in the aqueous phase is 0.1-0.5%.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The weight ratio of the aqueous phase to the oil phase is 5-25:1-8.

6. The preparation method according to claim 1, characterized in that, The emulsification temperature is 30–60°C, the time is 20–50 min, and the emulsification is carried out under stirring conditions at a stirring speed of 600–1000 rpm.

7. The preparation method according to claim 1, characterized in that, The polymerization is carried out at a temperature of 50–100°C for 5–8 hours, and is conducted under stirring conditions at a stirring speed of 600–1000 rpm.

8. Styrene microspheres prepared by the preparation method according to any one of claims 1 to 7.

9. A type of filler wax, characterized in that, Includes casting wax and fillers; the casting wax comprises the following components in weight percentages: Paraffin wax 20-40%, microcrystalline wax 5-25%, polyethylene wax 3-20%, resin 10-30%, dispersant 4-18%; The mass of the filler is 1 to 30% of the mass of the casting wax; The filler is the styrene microspheres as described in claim 8.

10. The method for preparing the filler wax according to claim 9, characterized in that, Includes the following steps: Paraffin wax, microcrystalline wax, polyethylene wax, resin, and dispersant are melt-mixed to obtain molten casting wax; The molten casting wax and filler are mixed and then solidified to obtain the filled wax material.

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