Method for producing modified hollow microspheres

Abstract

The invention discloses a method for manufacturing modified hollow microspheres. The method comprises the following steps: (a) uniformly mixing hollow spherical silicon dioxide, a siloxane coupling agent and an ethanol solution, and stirring for a first preset time; (b) adding an alkaline solution, and continuously stirring for a second preset time; (c) centrifuging, pouring out ethanol clarified liquid, and taking out powder; and (d) drying the powder in a vacuum environment to obtain the modified hollow microspheres. The weight ratio of the hollow silica to the siloxane coupling agent is 1: 10 to 1: 25. According to the manufacturing method of the modified hollow microspheres, the problems of incompatibility, processability and the like of existing hollow microspheres after silicon dioxide is directly added can be solved, and meanwhile, the electrical characteristics of a dielectric base material are improved.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing modified hollow microspheres, and particularly to a method for manufacturing modified hollow microspheres for high-frequency transmission. Background Art

[0002] In order to meet the requirements of high-frequency transmission, dielectric substrates used in electronic components must have characteristics such as low dielectric constant and low dielectric loss. In the prior art, hollow fillers are added to the dielectric substrate, and the characteristics of the air with low dielectric constant in the fillers are used to reduce the dielectric constant and dielectric loss of the dielectric substrate.

[0003] Furthermore, borosilicate glass hollow microspheres are widely used in the materials of dielectric substrates. However, borosilicate glass hollow microspheres contain various metal oxides such as sodium oxide (Na 2 O), boron oxide (B 2 O 3 ) and iron oxide (Fe 2 O 3 ), which will cause an increase in dielectric loss and a decrease in thermal stability. In addition, adding hollow glass easily results in a brittle mechanical property of the dielectric substrate.

[0004] Therefore, in the prior art, hollow silica fillers with excellent heat resistance, mechanical properties, and electrical properties are also used. However, the compatibility between the hollow silica fillers and the organic phase molecules in the dielectric substrate is not good.

[0005] Therefore, how to improve the compatibility of hollow silica fillers through molecular design modification to overcome the above defects has become one of the important issues to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a modified hollow microsphere that can be directly added to a dielectric substrate in view of the deficiencies of the prior art, so as to improve the problems such as incompatibility and processability after direct addition of hollow silica microspheres, and at the same time improve the electrical characteristics of the dielectric substrate.

[0007] To solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a method for manufacturing modified hollow microspheres, which includes the following steps: (a) uniformly mixing hollow spherical silica, a siloxane coupling agent, and an ethanol solution and stirring for a first predetermined time; (b) adding an alkaline solution and continuously stirring for a second predetermined time; (c) centrifuging and pouring out the ethanol clear liquid, and taking out the powder; and (d) drying the powder in a vacuum environment to obtain the modified hollow microspheres. The weight ratio of the hollow silica to the siloxane coupling agent is 1:10 to 1:25.

[0008] Further, the weight ratio of the hollow silica to the siloxane coupling agent is from 1:10 to 1:20.

[0009] Further, the pH value of the alkaline solution is from 10 to 12.

[0010] Further, the alkaline solution is ammonium chloride solution, sodium bicarbonate solution, sodium hydroxide solution or alkaline solution of alkali metal group (IA).

[0011] Further, the alkaline solution is 25% ammonium chloride solution.

[0012] Further, the siloxane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane or 3-acryloxypropyltrimethoxysilane.

[0013] Further, the first predetermined time is from 30 to 60 minutes.

[0014] Further, the second predetermined time is from 24 to 36 hours.

[0015] Further, steps (a) to (c) are carried out at room temperature.

[0016] Further, step (d) is carried out at 100°C for 2 hours.

[0017] One beneficial effect of the present invention is that the manufacturing method of the modified hollow microspheres provided by the present invention can improve the problems of incompatibility and processability after direct addition of existing hollow spherical silica, and at the same time improve the electrical properties of the dielectric layer through the technical solutions of "uniformly mixing hollow spherical silica, siloxane coupling agent and ethanol solution and stirring for a first predetermined time" and "the weight ratio of the hollow silica to the siloxane coupling agent is from 1:10 to 1:25".

[0018] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the provided drawings are only for reference and illustration, and are not used to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of the manufacturing method of the modified hollow microspheres of the present invention.

[0020] Figure 2 is a schematic diagram of the manufacturing method of the modified hollow microspheres of the present invention.

[0021] Figure 3 To compare the Fourier transform infrared spectra of the hollow microspheres before and after modification.

[0022] Reference numerals: S1 to S4: steps. Specific embodiments

[0023] The following are specific examples to illustrate the embodiments of the present invention regarding the "manufacturing method of modified hollow microspheres". Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments. Various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Additionally, the drawings of the present invention are only for simple schematic illustration and are not drawn according to actual dimensions. This is stated in advance. The following embodiments will further detail the relevant technical content of the present invention, but the disclosed content is not intended to limit the protection scope of the present invention.

[0024] It should be understood that although terms such as "first", "second", "third", etc. may be used herein to describe various elements or features, these elements or features should not be limited by these terms. These terms are mainly used to distinguish one element from another, or one feature from another. Additionally, the term "or" used herein may, depending on the actual situation, include any one or a combination of more of the associated listed items.

[0025] The manufacturing method of the modified hollow microspheres of the present invention is to first surface-modify the hollow spherical silica with a silane coupling agent. Compared with the prior art of adding a silane coupling agent to graft the hollow spherical silica with organic phase molecules, the modified hollow microspheres of the present invention have better compatibility and processability.

[0026] Refer to Figures 1 to 3 As shown, the present invention provides a manufacturing method of modified hollow microspheres, which at least includes the following steps. Step S1: Uniformly mix the hollow spherical silica, the siloxane coupling agent, and the ethanol solution and stir for a first predetermined time; Step S2: Add an alkaline solution and continuously stir for a second predetermined time; Step S3: Centrifuge and pour out the ethanol clear liquid, and take out the powder; and Step S4: Dry the powder in a vacuum environment to obtain the modified hollow microspheres.

[0027] Specifically, steps S1 to S3 are carried out at room temperature, where room temperature refers to 20 to 30 °C. The alkaline solution in step S2 is ammonium chloride solution, sodium bicarbonate solution, sodium hydroxide solution or alkaline solution of alkali metals (IA), and its pH value is 10 to 12 (for example, any positive integer between 10 and 12). In an embodiment of the present invention, the first predetermined time is 30 to 60 minutes, preferably 30 to 40 minutes (for example, any positive integer between 30 and 40). The second predetermined time is 24 to 36 hours, preferably 24 to 30 hours (for example, any positive integer between 24 and 30).

[0028] As Figure 2 shown, the present invention uses a siloxane coupling agent to modify hollow spherical silica, Figure 2 in which R1, R2 and R3 can be C1-C12 alkyl or its C1-C12 isomers. In an embodiment of the present invention, the siloxane coupling agent can be vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyl methyldimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyldiethoxysilane, 3-methacryloxypropyl triethoxysilane or 3-acryloxypropyl trimethoxysilane. However, the above examples are only one possible embodiment and are not intended to limit the present invention.

[0029] Furthermore, the weight ratio of hollow silica to the siloxane coupling agent is 1:10 to 1:25 to obtain a material having both CH 3 -CH 2 、C-CH 3, Modified hollow silica with C═C and -OH functional groups. In a preferred embodiment of the present invention, the weight ratio of hollow silica to siloxane coupling agent is from 1:10 to 1:20. For example, the weight ratio of hollow silica to siloxane coupling agent can be 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20. In a more preferred embodiment of the present invention, the weight ratio of hollow silica to siloxane coupling agent is 1:15.

[0030] Please refer to Figure 3 As shown, before and after modification, hollow silica has characteristic peaks at 825 and 1110 cm -1 , which are characteristic peaks of the silicon-oxygen functional groups (Si-O-Si) of hollow microspheres. After modification, hollow silica has characteristic peaks at 1420 and 2972 cm -1 respectively, representing the grafted CH 3 -CH 2 , C-CH 3 functional groups. After modification, hollow silica has a characteristic peak at 1620 cm -1 , representing the grafted vinyl double bond (C═C) functional group. After modification, hollow silica has a characteristic peak at 3503 cm -1 , representing the grafted hydroxyl functional group (-OH). That is to say, the modified hollow silica of the present invention simultaneously has CH 3 -CH 2 , C-CH 3 , C═C and -OH functional groups.

[0031] The manufacturing method of the modified hollow microspheres of the present invention is described in detail in Synthesis Examples 1 to 10 below.

[0032] Synthesis Example 1

[0033] Put 1 g of hollow spherical silica, 15 ml of vinyltrimethoxysilane and 100 ml of ethanol into a 250 ml reaction flask equipped with a thermometer and a stirrer, and stir at room temperature for 30 minutes. Subsequently, 10 ml of 25% NH 4 OH alkaline solution was added under continuous stirring, and stirred at room temperature for 24 hours. Then, centrifuge 3 times at 2000 rpm using a centrifuge, pour off the ethanol clear liquid and take out the powder. The powder was placed in a vacuum environment for 12 hours, and then dried at 100 °C for 2 hours to obtain the modified hollow microsphere powder (MS1-HS-SiO 2 ).

[0034] Synthesis Example 2

[0035] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to vinyltriethoxysilane, and the modified hollow microsphere powder (MS2-HS-SiO 2 ) was obtained.

[0036] Synthesis Example 3

[0037] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to p-styryltrimethoxysilane, and the modified hollow microsphere powder (MS3-HS-SiO 2 ) was obtained.

[0038] Synthesis Example 4

[0039] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to 3-methacryloxypropylmethyldimethoxysilane, and the modified hollow microsphere powder (MS4-HS-SiO 2 ) was obtained.

[0040] Synthesis Example 5

[0041] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to 3-methacryloxypropyltrimethoxysilane, and the modified hollow microsphere powder (MS5-HS-SiO 2 ) was obtained.

[0042] Synthesis Example 6

[0043] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to 3-methacryloxypropylmethyldiethoxysilane, and the modified hollow microsphere powder (MS6-HS-SiO 2 ) was obtained.

[0044] Synthesis Example 7

[0045] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to 3-methacryloxypropyltriethoxysilane, and the modified hollow microsphere powder (MS7-HS-SiO 2 ) was obtained.

[0046] Synthesis Example 8

[0047] Under the same process conditions as in Synthesis Example 1, the siloxane coupling agent was changed to 3-acryloxypropyltrimethoxysilane, and the modified hollow microsphere powder (MS8-HS-SiO 2 ) was obtained.

[0048] Synthesis Example 9

[0049] Place 1 g of hollow spherical silica, 15 ml of vinyltrimethoxysilane, and 100 ml of ethanol into a 250 ml reaction flask equipped with a thermometer and a stirrer, and stir at room temperature for 30 minutes. Subsequently, add 10 ml of 1% HCl acidic solution while continuously stirring, and stir at room temperature for 24 hours. Then, centrifuge 3 times at 2000 rpm using a centrifuge, pour off the ethanol clear liquid, and take out the powder. Place the powder in a vacuum environment for 12 hours, and then perform a drying step at 100 °C for 2 hours to obtain the modified hollow microsphere powder (MS9-HS-SiO 2 ).

[0050] Synthesis Example 10

[0051] Under the same process conditions as in Synthesis Example 9, the siloxane coupling agent was changed to 3-acryloxypropyltrimethoxysilane to obtain the modified hollow microsphere powder (MS10-HS-SiO 2 ).

[0052] Furthermore, the present invention also provides a resin composition containing modified hollow microspheres. Based on the total weight of the resin composition being 100 parts by weight, it includes: 10 to 80 parts by weight of modified hollow microspheres, 5 to 60 parts by weight of polyphenylene ether resin, and 5 to 30 parts by weight of a hardener. If the content of the modified hollow microspheres is less than 10 parts by weight, the dielectric constant and dielectric loss cannot be effectively reduced. If the content of the modified hollow microspheres is higher than 80 parts by weight, the coating characteristics of the resin composition will be affected. If the content of the polyphenylene ether resin is less than 5 parts by weight, the physical and mechanical properties, heat resistance, and electrical insulation of the resin composition will be poor. If the content of the polyphenylene ether resin is higher than 60 parts by weight, the melt viscosity of the resin composition will be large and it will be difficult to process. If the content of the hardener is less than 5 parts by weight, the resin cannot be smoothly cured after coating. If the content of the hardener is higher than 30 parts by weight, the texture of the cured resin composition will be too hard and brittle.

[0053] In a preferred embodiment of the present invention, the resin composition of the modified hollow microspheres includes 30 to 70 parts by weight of modified hollow microspheres, 10 to 50 parts by weight of polyphenylene ether resin, and 5 to 20 parts by weight of a hardener. In a more preferred embodiment of the present invention, the resin composition of the modified hollow microspheres includes 50 to 70 parts by weight of modified hollow microspheres, 20 to 30 parts by weight of polyphenylene ether resin, and 10 to 20 parts by weight of a hardener. In an even more preferred embodiment of the present invention, the weight ratio of the modified hollow microspheres, polyphenylene ether resin, and hardener is 65:24:11.

[0054] Specifically, the hardener can be trimethallyl isocyanate (TMAIC), triallyl isocyanurate (TAIC), 1,3-isopropenyl-α-methylstyrene / 1,4-isopropenyl-α-methylstyrene (IP-AMS), 2,2'-diallyl bisphenol A (Di-ally BPA), divinylbenzene (DVB), 1,2-bis(p-vinylphenyl)ethane (BVPE). However, the examples given above are only one feasible embodiment and are not intended to limit the present invention.

[0055] The present invention can also provide a resin composition, which is made by mixing the modified hollow microsphere powder prepared by the method of the present invention with resin, hardener, catalyst, reinforcing material, etc., that is, mixing and dissolving or dispersing in a solvent with a homogenizing mixer to form a varnish-like state for subsequent processing and utilization. For example, the catalyst can be a peroxide, an azo compound (such as α,α'-azobis(isobutyronitrile)), a redox initiator (such as a combination of peroxides, for example, a combination of hydrogen peroxide and ferrous salt), or an azide (such as vinyl azide). In an embodiment of the present invention, the catalyst can be a peroxide-based hardening accelerator, such as cyclohexanone peroxide, tert-butyl perbenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, cumyl tert-butyl peroxide, di-tert-butyl peroxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, tert-butyl hydroperoxide. Preferably, the peroxide-based hardening accelerator is dicumyl peroxide (DCP) commercially purchased from Arkema.

[0056] The solvent can be any inert solvent that can dissolve or disperse the components of the resin composition but does not react with these components. The aforementioned solvents include but are not limited to: toluene, γ-butyrolactone, methyl ethyl ketone, cyclohexanone, butanone, acetone, xylene, methyl isobutyl ketone, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP). Each solvent can be used alone or in combination. The amount of the solvent is not particularly limited. In principle, as long as it can uniformly dissolve or disperse the components of the resin composition therein. In the appended examples, a mixture of toluene, methyl ethyl ketone, and γ-butyrolactone is used as the solvent.

[0057] The present invention also provides a prepreg sheet, which is prepared by impregnating or coating a substrate with a resin composition of modified hollow microspheres and drying the impregnated or coated substrate. The impregnated or coated substrate can be dried at a temperature of 80°C to 180°C for 1 to 10 minutes (for example, any positive integer between 1 and 10) to obtain a semi-cured prepreg sheet. In an embodiment of the present invention, 2116 reinforced fiberglass cloth is used as the substrate (reinforcement), and it is heated and dried at 175°C for 2 to 15 minutes (for example, any positive integer between 2 and 15) to prepare a semi-cured prepreg sheet.

[0058] Furthermore, a metal foil laminate and a printed circuit board can be prepared by laminating the above prepreg sheet with a metal foil. In an embodiment of the present invention, four prepreg sheets impregnated or coated with the aforementioned resin composition can be laminated respectively, and a 0.5 ounce copper foil is laminated on each of the outermost layers on both sides thereof, and then placed in a hot press for high-temperature hot pressing and curing to obtain a printed circuit board. Specifically, the hot pressing conditions are: heating up to 200°C to 220°C (for example, any positive integer between 200 and 220) at a heating rate of 3.0°C / minute, and at this temperature, hot pressing for 180 minutes at a full pressure of 15 kg / cm² (initial pressure 8 kg / cm²).

[0059] Next, property tests of the glass transition temperature (Tg), coefficient of thermal expansion (CTE), dielectric constant (Dk), dielectric loss (Df), and compatibility of the dielectric substrate layer are carried out. The components of the resin composition and the test results are listed in Table 1. EX1 to EX8 in Table 1 represent Examples 1 to 8, and C1 to C12 represent Comparative Examples 1 to 12.

[0060] CTE Test

[0061] According to the IPC-TM-650 2.4.24.5 specification, a thermal mechanical analyzer (TMA) is used to measure the change rate of the coefficient of thermal expansion (total z-CTE) in the Z-axis direction of the coefficient of thermal expansion of the sample to be tested at a temperature below Tg.

[0062] Compatibility Test

[0063] The powder filler is placed in a varnish solution and left to stand at room temperature for 2 hours, and then observed whether the powder is suspended or not; if there is surface suspension, it is marked (X), and conversely, if it is uniformly mixed, it is marked (O).

[0064] Dielectric Constant and Dielectric Loss Measurement

[0065] Remove the laminated substrate from the hot press and remove the copper foil by etching to form a specimen; measure the dielectric constant and loss factor at 10 GHz using the clamped strip line test method described in IPC-TM-650 2.5.5.5.1.

[0066] The composition and physical property measurement results of the examples of this case are shown in Table 1, and the composition and physical property measurement results of the comparative examples are shown in Table 2. The contents in Tables 1 and 2 are expressed in parts by weight. The composition of the examples of this case is based on the total volume of all components being 100%, where 50% by volume is hollow microspheres, 25% by volume is a reinforcing material, and 25% by volume is resin, catalyst, and flame retardant.

[0067] Table 1

[0068]

[0069]

[0070] Table 2

[0071]

[0072]

[0073] Table 2 (continued)

[0074]

[0075] In Tables 1 and 2, silane 1 is vinyltrimethoxysilane; silane 4 is 3-Methacryloxypropylmethyldimethoxysilane. The peroxide is dicumyl peroxide (DCP) commercially purchased from Arkema.

[0076] As shown in Table 1, the modified hollow microspheres of the present invention have excellent compatibility with other materials of the dielectric substrate, and using the modified hollow microspheres of the present invention can make the dielectric constant of the dielectric substrate less than 2.9 at 10 GHz, and the dielectric loss of the dielectric substrate layer is less than 0.003 at 10 GHz.

[0077] The modified hollow microspheres of the present invention are manufactured in an alkaline environment to obtain a lower dielectric constant and dielectric loss. For example, in Comparative Examples C1 and C2, although the siloxane coupling agent used is the same as that of the embodiment of the present case, the modified hollow microspheres of Comparative Examples C1 and C2 are modified in an acidic environment (pH 3 to 5.5), resulting in poor electrical properties of the modified hollow microspheres.

[0078] In addition, although the unmodified hollow microspheres used in Comparative Examples C3 to C5 also have lower dielectric constants and dielectric losses, their compatibility is poor. Comparative Examples C6 and C7 use glass hollow microspheres and spherical silica, which have poor compatibility and poor electrical properties, respectively.

[0079] In addition, Comparative Examples C8 to C12 show that even if glass hollow microspheres or spherical silica are mixed with the modified hollow microspheres of the present invention, there are still disadvantages such as poor compatibility and poor electrical properties. Therefore, the modified hollow microspheres of the present invention need to be used in a specific amount to achieve the effect of taking into account both compatibility and electrical properties.

[0080] Advantageous Effects of Embodiments

[0081] One of the beneficial effects of the present invention is that the method for manufacturing modified hollow microspheres provided by the present invention can improve the problems of incompatibility and processability after direct addition of existing hollow spherical silica, and at the same time improve the electrical properties of the dielectric layer through the technical scheme of "uniformly mixing the hollow spherical silica, the siloxane coupling agent and the ethanol solution and stirring for a first predetermined time" and "the weight ratio of the hollow silica to the siloxane coupling agent is 1:10 to 1:25".

[0082] Furthermore, the modified hollow microspheres produced by the method of the present invention can be blended with other thermosetting polymers, inorganic fillers or fibers to form composite materials with low dielectric properties and excellent mechanical properties, thus having a wide range of applications in the fields of electronics, aerospace, etc.

[0083] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the protection scope of the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention description and drawings are included in the protection scope of the claims of the present invention.

Claims

1. A manufacturing method of modified hollow microspheres, characterized in that, the manufacturing method of the modified hollow microspheres comprises the following steps: (a) Uniformly mixing hollow spherical silica, a siloxane coupling agent and an ethanol solution and stirring for a first predetermined time; (b) Adding an alkaline solution and continuously stirring for a second predetermined time; (c) Centrifuging and pouring out the ethanol clear liquid, and taking out the powder; and (d) Drying the powder in a vacuum environment to obtain the modified hollow microspheres; wherein, the weight ratio of the hollow silica to the siloxane coupling agent is 1:10 to 1:

25.

2. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the weight ratio of the hollow silica to the siloxane coupling agent is 1:10 to 1:

20.

3. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the pH value of the alkaline solution is 10 to 12.

4. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the alkaline solution is ammonium chloride solution, sodium bicarbonate solution or sodium hydroxide solution and alkali metal group (IA) alkaline solution.

5. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the alkaline solution is 25% ammonium chloride solution.

6. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the siloxane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane or 3-acryloxypropyltrimethoxysilane.

7. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the first predetermined time is 30 to 60 minutes.

8. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, the second predetermined time is 24 to 36 hours.

9. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, steps (a) to (c) are carried out at room temperature.

10. The manufacturing method of the modified hollow microspheres according to claim 1, characterized in that, step (d) is carried out at 100 °C for 2 hours.

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