Fluororesin composition, laminate for substrates and printed wiring board

Abstract

To provide a resin composition that is easy to mold, offers high mechanical strength even in a thin film, reduces hygroscopicity, and exhibits low dielectric loss tangent and dielectric constant, and a substrate including the same.SOLUTION: A fluororesin composition includes: amorphous hollow silica particles with their surfaces treated with a fluorine-containing silane coupling agent or both the fluorine-containing silane coupling agent and an amino group-containing silane coupling agent, featuring a shell thickness of 10-50 nm and an average particle size of 50 nm or more and less than 10 μm; fluororesin; and a fluorine-based surfactant.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a fluororesin composition, a laminate for a substrate, and a printed wiring board. [Background technology]

[0002] In recent years, there has been a demand for smaller electronic devices, faster signal speeds, and higher wiring density. To meet these demands, there has been a demand for resin compositions used in insulating resin sheets such as adhesive films and prepregs, as well as insulating layers formed on printed wiring boards, to have lower relative dielectric constants, lower dielectric loss tangents, and lower thermal expansion.

[0003] In order to meet these requirements, the use of hollow particles as a filler has been investigated, and various proposals have been made. For example, Patent Document 1 describes a resin composition containing (A) an epoxy resin, (B) a curing agent, (C) hollow silica, and (D) fused silica. Patent Document 2 describes a low dielectric resin composition containing hollow particles and a thermosetting resin, in which 98 mass % or more of the entire shell of the hollow particles is formed of silica, the average porosity is 30 to 80 volume %, and the average particle size is 0.1 to 20 μm.

[0004] In addition, various proposals have been made regarding hollow silica materials used as low dielectric constant materials. For example, Patent Document 3 discloses hollow silica particles having a shell layer containing silica and having a space inside the shell layer, and the hollow silica particles have a wavelength of 3746 cm by infrared spectroscopy. -1 Hollow silica particles have been proposed in which the peak intensity derived from SiOH in the vicinity of the above-mentioned range is 0.60 or less, the relative dielectric constant at 1 GHz is 1.3 to 5.0, and the dielectric tangent at 1 GHz is 0.0001 to 0.05. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-173841 A [Patent Document 2] JP 2008-031409 A [Patent Document 3] International Publication No. 2021 / 172294 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if hollow silica particles are broken when kneaded with resin, it may cause poor dispersion or deteriorate the dielectric properties. In addition, if hydrophilic groups are present on the particle surface, the resin may absorb water, which may affect the dielectric properties. In addition, if thick crystalline hollow silica particles are used to maintain the mechanical strength of the hollow silica particles, the hollow space of the particles may become small, making it difficult to obtain the desired dielectric properties.

[0007] On the other hand, when a fluororesin is used as the resin, which is the dispersion medium, electrical properties such as the dielectric tangent and the relative dielectric constant are improved. However, simply mixing a fluororesin with an inorganic filler causes problems such as a decrease in the mechanical strength of the insulating layer and an increase in transmission loss.

[0008] Therefore, an object of the present invention is to provide a resin composition that is easy to mold, has sufficient mechanical strength even when formed into a thin film, has low moisture absorption, and has a low dielectric tangent and dielectric constant, and a substrate using the same. [Means for solving the problem]

[0009] As a result of intensive research, the present inventors have developed durable hollow particles by modifying the particle surface with an organic functional group containing a fluorine atom to form amorphous hollow silica particles with a thin shell thickness and small particle size. Furthermore, they have found that a fluororesin composition in which the surface-modified hollow silica particles are blended with a fluororesin surfactant maintains mechanical strength and exhibits low dielectric properties even when made into a thin film.

[0010] The present invention relates to the following (1) to (13). (1) A fluororesin composition comprising: amorphous hollow silica particles having a surface treated with a fluorine-containing silane coupling agent, or a fluorine-containing silane coupling agent and an amino group-containing silane coupling agent, the shell thickness being 10 to 50 nm, and the average particle size being 50 nm or more and less than 10 μm; a fluororesin; and a fluorosurfactant. (2) The fluororesin composition according to (1) above, wherein the content of the hollow silica particles is 10 to 60% by volume. (3) The fluororesin composition according to (1) or (2) above, which contains 1 to 10 parts by mass of the fluorosurfactant per 100 parts by mass of the fluororesin. (4) The fluororesin composition according to any one of (1) to (3), wherein the fluorine-containing silane coupling agent is either trifluoropropyltrimethoxysilane or trifluoropropyltriethoxysilane, and the amino group-containing silane coupling agent is either 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane. (5) The fluororesin composition according to any one of (1) to (4), wherein the fluororesin is a thermoplastic fluororesin having a melting point of 260 to 400°C. (6) The fluororesin composition according to any one of (1) to (5) above, wherein the fluororesin is a thermoplastic fluororesin having a tetraethylene group and further having at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, an amide group, an amino group, an isocyanate group, a fluoroformyl group, and an acid anhydride residue. (7) The fluororesin composition according to any one of (1) to (6) above, which is for a printed wiring board. (8) An insulating film formed from the fluororesin composition according to any one of (1) to (7) above. (9) A treated substrate comprising: a substrate; and a thin film having a thickness of 10 to 100 μm, which is formed from the fluororesin composition according to any one of (1) to (7) above, disposed on a surface of the substrate. (10) A printed wiring board comprising a metal foil substrate and a thin film formed on a surface of the metal foil substrate from the fluororesin composition according to any one of (1) to (7). (11) The printed wiring board according to (10) above, wherein the metal foil substrate is a copper foil substrate. (12) The printed wiring board according to (10) or (11) above, wherein the thin film has a thickness of 10 to 100 μm. (13) A method for producing a printed wiring board according to any one of (10) to (12) above, comprising forming a layer of the fluororesin composition according to any one of (1) to (7) above on a surface of a metal foil substrate, and heating the resulting layer. Effect of the Invention

[0011] The fluororesin composition of the present invention is easy to mold, has sufficient mechanical strength even when formed into a thin film, has low moisture absorption, and has a low dielectric tangent and dielectric constant. Therefore, laminates and printed wiring boards having an insulating film formed from the fluororesin composition of the present invention have excellent dielectric properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described below, but the present invention is not limited to the examples in the following description. In this specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after the symbol "to" are included as the lower and upper limits.

[0013] <Fluororesin composition> The fluororesin composition of the present invention comprises amorphous hollow silica particles having a surface treated with a fluorine-containing silane coupling agent or a fluorine-containing silane coupling agent and an amino group-containing silane coupling agent, a shell thickness of 10-50 nm, and an average particle size of 50 nm or more and less than 10 μm, a fluororesin, and a fluorine-based surfactant. Hereinafter, the surface-modified hollow silica particles whose particle surface is treated with the silane coupling agent are also simply referred to as "hollow silica particles".

[0014] (Hollow Silica Particles) The hollow silica particles used in the present invention (surface-modified hollow silica particles treated with the above-mentioned silane coupling agent) have a shell layer containing silica and have a space inside the shell layer. The fact that the hollow silica particles have a space inside the shell layer can be confirmed by observation with a transmission electron microscope (TEM) or a scanning electron microscope (SEM). In the case of SEM observation, it can be confirmed that the particles are hollow by observing broken particles with some openings.

[0015] In this specification, the shell layer "contains silica" means that the silica layer contains 50% or more by mass of silica (SiO2). The composition of the shell layer can be measured by ICP emission spectrometry, flame atomic absorption spectrometry, or the like. The silica content of the shell layer is preferably 80% or more by mass, more preferably 95% or more by mass. The upper limit is theoretically 100% by mass. The silica content of the shell layer is preferably less than 100% by mass, more preferably 99.99% by mass or less. The remainder includes alkali metal oxides, carbon, and the like. Furthermore, "having a space inside the shell layer" means that when a cross section of a primary particle is observed, a space is surrounded by a shell layer, creating a hollow state. In other words, a hollow particle has a large space surrounded by a shell layer.

[0016] The hollow silica particles used in the present invention are raw material hollow silica particles whose surfaces have been treated with a fluorine-containing silane coupling agent or a fluorine-containing silane coupling agent and an amino group-containing silane coupling agent. By treating the particle surfaces with the above-mentioned silane coupling agent, the amount of remaining surface silanol groups is reduced, the surface is hydrophobicized, and moisture adsorption is suppressed, improving dielectric loss. In addition, when the particles are made into a resin composition, their affinity with the resin is improved, improving dispersibility and strength after formation of a resin film.

[0017] In addition, "the surface of the hollow silica particles is treated with a fluorine-containing silane coupling agent or a fluorine-containing silane coupling agent and an amino group-containing silane coupling agent" means that the fluorine-containing silane coupling agent or the fluorine-containing silane coupling agent and the amino group-containing silane coupling agent are adsorbed to the surface of the hollow silica particles by chemical bonding rather than physical bonding. The above-mentioned silane coupling agent has a hydrolyzable group such as an alkoxy group on the central silicon atom, which is hydrolyzed and undergoes a dehydration condensation reaction with the silanol group (SiOH group) on the surface of the raw hollow silica particles. This treatment causes the silane coupling agent residue having a fluorine atom or an amino group to bond to the surface of the raw hollow silica particles through the silane coupling reaction. Note that the silane coupling agents may also bond to each other due to the hydrolysis of the hydrolyzable group remaining in the silane coupling agent bonded to the surface of the raw hollow silica particles.

[0018] Examples of fluorine-containing silane coupling agents include trifluoropropyltrimethoxysilane (TFPTMS), trifluoropropyltriethoxysilane, perfluorodecyltrimethoxysilane, perfluorodecyltriethoxysilane, perfluorooctyltrimethoxysilane, perfluorooctyltriethoxysilane, heptadecafluorotetrahydrodecyltriethoxysilane, perfluorohexylethyltrimethoxysilane, perfluorohexylethyltriethoxysilane, perfluorohexylethyltrichlorosilane, etc. These may be used alone or in combination of two or more. Among these, from the viewpoint of suppressing harmfulness and accumulation to the human body and the global environment, trifluoropropyltrimethoxysilane (TFPTMS) and trifluoropropyltriethoxysilane are preferred, and trifluoropropyltrimethoxysilane (TFPTMS) is more preferred.

[0019] Examples of amino group-containing silane coupling agents include 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane, 4-amino3,3-dimethylbutyltriethoxysilane, N-methylaminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, 2-(4-pyridylethyl)triethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylsilanetriol, 3-trimethoxypropyldiethyldiethylenetriamine, N,N'-BIS[ Examples of the silane derivatives include (3-trimethoxysilyl)propyl]ethylenediamine, [3-(1-piperazinyl)propyl]methyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, bis[3-(trimethoxysilyl)propyl]amine, etc. These may be used alone or in combination of two or more. Among these, from the viewpoint of excellent reactivity with the surface of the raw material hollow silica particles, 3-aminopropyltriethoxysilane (APTES) and 3-aminopropyltrimethoxysilane are preferred, and 3-aminopropyltriethoxysilane (APTES) is more preferred.

[0020] In the present invention, from the viewpoint of easily improving dispersibility in resin composition, it is preferable that 30% by mass or more of the total silane coupling agent that covers the surface of raw material hollow silica particle is a fluorine-containing silane coupling agent.Since the fluorine-containing silane coupling agent has the characteristics of extremely low surface tension and surface free energy, it is easy to make the silica surface low hygroscopic, and it is assumed that this makes it easy to improve the dispersibility of hollow silica particle in resin composition. The content of the fluorine-containing silane coupling agent on the surface of the hollow silica particles is more preferably 50 mass% or more of the total silane coupling agent, and even more preferably 60 mass% or more, and it is particularly preferable that the surface is treated with only the fluorine-containing silane coupling agent.

[0021] The amount of the silane coupling agent is preferably 0.1 to 15 parts by mass relative to 100 parts by mass of raw hollow silica particles. When the amount of the silane coupling agent is 0.1 parts by mass or more relative to 100 parts by mass of raw hollow silica particles, the effect of the present invention can be obtained, and when it is 15 parts by mass or less, the self-condensation of the silane coupling agent is suppressed, and the silane coupling agent is selectively reacted with the surface of the hollow silica particles. The amount of the silane coupling agent is preferably 0.1 parts by mass or more relative to 100 parts by mass of raw hollow silica particles, more preferably 0.5 parts by mass or more, even more preferably 1.0 parts by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0022] The fact that the surface of the hollow silica particles has been treated with the silane coupling agent can be confirmed by detecting a peak due to a substituent of the silane coupling agent by IR. The amount of the silane coupling agent attached can be measured by measuring the carbon amount or thermogravimetry (TG).

[0023] The hollow silica particles of the present invention have a wave number of 3746 cm according to infrared spectroscopy. -1 It is preferable that the peak intensity derived from SiOH (silanol group) near the surface of the film is 0.60 or less, the relative dielectric constant at 1 GHz is 1.3 to 5.0, and the dielectric loss tangent at 1 GHz is 0.0001 to 0.05. -1 When the peak intensity derived from the SiOH in the vicinity, the relative dielectric constant, and the dielectric loss tangent satisfy the above-mentioned relationships, a substrate having low dielectric loss and sufficient compatibility with high frequency circuits can be provided.

[0024] Infrared spectroscopy wave number 3746 cm -1The SiOH-derived peak intensity in the vicinity of the wave number of 3746 cm is preferably 0.60 or less. If the SiOH-derived peak intensity is greater than 0.60, the dielectric loss tangent component derived from SiOH tends to be more pronounced, and the dielectric loss tangent tends to deteriorate. -1 The peak intensity derived from SiOH in the vicinity of 3746 cm is more preferably 0.40 or less, further preferably 0.30 or less, particularly preferably 0.20 or less, and most preferably 0.10 or less. -1 The lower the peak intensity derived from SiOH in the vicinity, the lower the dielectric tangent, and therefore the lower the better, and the lower limit is not particularly limited.

[0025] Here, "near" refers to the wave number 3746 cm -1 In the vicinity, the wave number of the peak center is 3746 cm -1 And the width from front to back is 14cm. -1 The wave number is 3732 cm -1 Wave number 3760cm -1 The same applies to other wave numbers.

[0026] Infrared spectroscopy wave number 3746 cm -1 The peak intensity due to SiOH in the vicinity was determined by the diffuse reflection method, and was found to be due to the absorption of SiOH (wave number 3746 cm -1 (around 1060 cm) -1 It can be obtained by normalizing the peak intensity derived from various SiOH in the vicinity to 1.

[0027] The hollow silica particles of the present invention preferably have a relative dielectric constant of 1.3 to 5.0 at 1 GHz. In particular, in measuring the dielectric constant of powder, the sample space becomes small at frequencies above 10 GHz, resulting in poor measurement accuracy, so the measured value at 1 GHz is adopted in the present invention. When the relative dielectric constant at 1 GHz is within the above range, the low relative dielectric constant required for electronic devices can be achieved. It is practically difficult to synthesize hollow silica particles having a relative dielectric constant of less than 1.3 at 1 GHz. The lower limit of the relative dielectric constant at 1 GHz is more preferably 1.4 or more, and even more preferably 1.5 or more, and the upper limit is more preferably 4.5 or less, even more preferably 4.0 or less, particularly preferably 3.5 or less, even more preferably 3.0 or less, and most preferably 2.5 or less.

[0028] In addition, the hollow silica particles of the present invention preferably have a dielectric loss tangent of 0.0001 to 0.05 at 1 GHz. If the dielectric loss tangent at 1 GHz is 0.05 or less, the low relative dielectric constant required for electronic devices can be achieved. In addition, it is substantially difficult to synthesize hollow silica particles having a dielectric loss tangent of less than 0.0001 at 1 GHz. The lower limit of the dielectric loss tangent at 1 GHz is more preferably 0.0005 or more, and even more preferably 0.0006 or more.The upper limit is more preferably 0.04 or less, even more preferably 0.03 or less, even more preferably 0.02 or less, particularly preferably 0.01 or less, even more preferably 0.005 or less, and most preferably 0.003 or less.

[0029] The relative dielectric constant and the dielectric loss tangent can be measured by a perturbation resonator method using a dedicated device (for example, "Vector Network Analyzer E5063A" manufactured by Keycom Corporation).

[0030] The shell thickness of the hollow silica particles is 10 to 50 nm. If the shell thickness is 10 nm or more, the strength of the particles can be maintained, and if it is 50 nm or less, the voids do not become too small, and excellent dielectric properties can be obtained. The shell thickness is preferably 12 nm or more, more preferably 15 nm or more, and is preferably 40 nm or less, more preferably 30 nm or less.

[0031] The shell thickness of the hollow silica particles is preferably 0.01 to 0.3 with respect to the primary particle diameter of 1. If the shell thickness is less than 0.01 with respect to the primary particle diameter of 1, the strength of the hollow silica particles may decrease. If this ratio is more than 0.3, the hollow space inside the particle becomes small, and the characteristics due to the hollow shape are not exhibited. The shell thickness is more preferably 0.02 or more, and even more preferably 0.03 or more, and more preferably 0.2 or less, and even more preferably 0.1 or less, relative to the diameter of the primary particle.

[0032] Here, the shell thickness is determined by measuring the shell thickness of each particle using a transmission electron microscope (TEM).

[0033] The average size of the primary particles of hollow silica particles (average particle size) is in the range of 50 nm to less than 10 μm. If the average particle size is less than 50 nm, the specific surface area, oil absorption, and pore volume increase, the amount of SiOH and adsorbed water on the particle surface increase, and the dielectric tangent tends to increase. Also, if the average particle size is less than 10 μm, it is easy to handle as a filler. From the viewpoint of production reproducibility, the average particle size has a lower limit of preferably 70 nm or more, more preferably 100 nm or more, and an upper limit of preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less.

[0034] The size of the primary particles of hollow silica particles can be determined by directly observing the particle size (diameter) using SEM observation. Specifically, the primary particle size of 100 particles is measured from SEM images, and the distribution of primary particle sizes obtained by tallying these up is estimated to be the distribution of the overall primary particle size. SEM observation makes it possible to directly measure the primary particle size of particles that are difficult to deflocculate.

[0035] The silica particles contained in the composition preferably have a unimodal particle size distribution, which can be confirmed by the presence of one peak in the particle size distribution measured by the laser diffraction / scattering method described above.

[0036] The average particle size of hollow silica particles (diameter of secondary particles) is preferably measured by laser scattering. Measuring the aggregate size by SEM is because the boundaries between particles are unclear and does not reflect the dispersion in a wet state. In addition, when measuring by a Coulter counter, the electric field changes are different between hollow particles and solid particles, making it difficult to obtain a value corresponding to the solid particles.

[0037] The coarse particle diameter (D90) of the secondary particles of the hollow silica particles is preferably 1 to 30 μm. From the viewpoint of production efficiency, the coarse particle diameter is preferably 1 μm or more. If the coarse particle diameter is too large, it will cause granulation when the resin composition is molded into a film, so it is preferably 30 μm or less. The lower limit of the coarse particle diameter is more preferably 3 μm or more, most preferably 5 μm or more, and the upper limit is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and most preferably 15 μm or less.

[0038] As described above, the coarse particle size can also be determined by measuring the particle size of secondary particles by laser scattering.

[0039] The hollow silica particles used in the present invention have a density of 2.00 to 2.30 g / cm, as determined by density measurement using a dry pycnometer using helium gas (hereinafter also referred to as the helium pycnometer method). 3 It is preferable that: The density measured by the helium pycnometer method indicates whether the shell layer of the hollow silica particles has pores. If the density of the hollow silica particles measured by the helium pycnometer method is 2.00 g / cm 3 If this is the case, it is understood that the helium gas has penetrated into the inside of the particle and is retained in the internal space, and therefore it is understood that the shell layer has pores.

[0040] The density of hollow silica particles measured by helium pycnometer method is 2.00g / cm 3If the density is 2.30 g / cm or more, the shell layer becomes a dense silica layer, making the hollow silica particles less susceptible to breakage. 3 If the density is less than 2.05g / cm, the silica becomes amorphous with low crystallinity, and the relative dielectric constant is kept low. The density of hollow silica particles measured by helium pycnometer method has a lower limit of 2.05g / cm 3 More preferably, it is 2.07 g / cm or more. 3 More preferably, 2.09 g / cm 3 More preferably, 2.10 g / cm 3 More than this is most preferable, with the upper limit being 2.25 g / cm 3 It is more preferable that:

[0041] The hollow silica particles have a density of 0.35 g / cm as determined by density measurement using a dry pycnometer with argon gas (hereinafter also referred to as the argon pycnometer method). 3 ~2.00g / cm 3 It is preferable that: The density measured by the argon pycnometer method can tell whether the hollow silica particles are hollow or not. Since argon gas has a larger molecular size than helium gas, if the shell layer is dense, it cannot pass through the shell layer, and the apparent density of the particle is measured.

[0042] The density of hollow silica particles measured by argon pycnometer method is 2.00g / cm 3 If the apparent density is less than the true density of silica (approximately 2.20 g / cm 3 ), it can be determined that there is a space inside the particle. Also, the density is 0.35g / cm 3 If the amount is more than this, the shell strength of the hollow silica particles can be maintained.

[0043] In addition, the density measured by the argon pycnometer method is lower than that measured by the helium pycnometer method, so that minute gas molecules can pass through the inside of the hollow silica particles, and the inside of the particles is at normal pressure.Particles with a very dense shell such as glass balloons are easily crushed when they are made into a resin composition by stirring or kneading, because there is a pressure difference between the inside of the particle and the atmosphere, but the hollow silica particles of the present invention are not easily crushed by the above-mentioned operations because the pressure difference between the inside of the particle and the atmosphere is small.

[0044] The density of hollow silica particles determined by the argon pycnometer method has a lower limit of 0.40 g / cm3 from the viewpoint of the strength of the particle shell. 3 More preferably, it is 0.50 g / cm or more. 3 More preferably, 0.60 g / cm 3 More preferably, 0.70 g / cm 3 More preferably, 0.80 g / cm 3 The upper limit is 1.70 g / cm from the viewpoint of maintaining the air content and suppressing an increase in the relative dielectric constant. 3 More preferably, it is 1.60 g / cm or less. 3 More preferably, 1.50 g / cm 3 The following is particularly preferred: 1.40 g / cm 3 The following are most preferred:

[0045] The apparent density of hollow silica particles can also be measured using a pycnometer. The sample (hollow silica particles) and an organic solvent are placed in the pycnometer, and the sample is left to stand at 25°C for 48 hours before measurement. Depending on the density of the shell of the hollow silica particles, it may take some time for the organic solvent to penetrate, so it is preferable to leave the sample to stand for the above period of time. The results of measurements using this method correspond to the results of density measurements using a dry pycnometer using argon gas.

[0046] The apparent density of hollow silica particles can be adjusted by adjusting the primary particle size and shell thickness, and by changing the particle density, it is possible to control whether the particles will settle in the solvent, remain dispersed, or float to the top. If you want to disperse the particles in a solvent, it is desirable for the density of the solvent and the apparent density of the particles to be close to each other. For example, if the density is 1.0 g / cm 3 If you want to disperse the particles in water, you need to make the apparent density of the particles 0.8 g / cm 3 More than 1.2g / cm 3 It is preferable to adjust as follows:

[0047] The average pore diameter of the hollow silica particles is preferably 1 nm or less. If the average pore diameter is 1 nm or less, the intrusion of resin components, surfactants, solvents, etc. into the pores can be prevented. The average pore diameter is more preferably 0.8 nm or less, and even more preferably 0.4 nm or less. The smaller the pore diameter, the less the oil absorption, and the more the porosity can be maintained and the deterioration of the dielectric properties can be prevented, so the lower limit is not particularly limited.

[0048] The pore size is determined by the BET method based on the nitrogen adsorption method using a specific surface area / pore size distribution measuring device (e.g., Microtrack-Bell's "BELSORP-miniII" and Micromeritics' "Tristar II"). The average pore size is determined by analyzing the pore size distribution from the pore volume and specific surface area determined by the BET method.

[0049] Hollow silica particles have a BET specific surface area of ​​1 to 100 m 2 / g. It is preferable that the BET specific surface area is 1 m 2 When the resin composition is prepared by adding a 100m 2 / g or less, the amount of oil absorption can be suppressed and the amount of adsorbed water can be reduced. The denser the shell, the smaller the specific surface area. Therefore, the BET specific surface area is 90m 2 / g or less is more preferable, and 2 / g or less is more preferable. 2 / g or more is more preferable, and 2 / g or more is more preferable, and 5m 2 / g or more is most preferred.

[0050] Here, the BET specific surface area can be measured using a specific surface area measuring device (e.g., Shimadzu Corporation's Tristar II3020) by drying the hollow silica particles at 230°C to 50 mTorr as a pretreatment, and then measuring by a multipoint method using liquid nitrogen.

[0051] The sphericity of the hollow silica particles is preferably 0.75 to 1.0. If the sphericity is low, the hollow silica particles become more susceptible to breakage, and the density measured by the argon pycnometer method decreases, the specific surface area increases, and the dielectric loss tangent increases.

[0052] Sphericity is expressed as the average value of the ratio (DS / DL) of the minimum diameter (DS) to the maximum diameter (DL) of 100 random particles in a photographic projection obtained by photographing with a scanning electron microscope (SEM).

[0053] From the viewpoint of dispersibility, the sphericity is more preferably 0.80 or more, even more preferably 0.82 or more, even more preferably 0.83 or more, particularly preferably 0.85 or more, even more preferably 0.87 or more, and most preferably 0.90 or more.

[0054] Since hollow silica particles have a space inside, they can contain substances inside the particles. The hollow silica particles used in the present invention have a dense shell layer, which makes it difficult for various solvents to penetrate, but if there are damaged particles, the solvent will penetrate inside. Therefore, the oil absorption changes depending on the proportion of damaged particles.

[0055] The oil absorption of the hollow silica particles is preferably 15 to 1300 mL / 100 g. When the oil absorption is 15 mL / 100 g or more, adhesion to a resin can be ensured when the particles are used in a resin composition, and when the oil absorption is 1300 mL / 100 g or less, strength of the resin can be ensured when the particles are used in a resin composition, and the viscosity of the composition can be reduced. Since a high oil absorption leads to high viscosity, the oil absorption of the hollow silica particles is more preferably 1000mL / 100g or less, even more preferably 700mL / 100g or less, particularly preferably 500mL / 100g or less, and most preferably 200mL / 100g or less. In addition, if the oil absorption is too low, the adhesion between the powder and the resin may deteriorate, so it is more preferably 20mL / 100g or more.

[0056] The pore volume of a hollow silica particle is 0.2 cm 3 It is preferable that the molecular weight is not more than 1 / g. Pore ​​volume is 0.2 cm 3 If the pore volume is greater than 0.15 cm3 / g, the resin composition may easily adsorb moisture and have a deteriorated dielectric loss. 3 / g or less is more preferable, and 0.1 cm 3 / g or less is more preferable, and 0.05 cm 3 / g or less is particularly preferred.

[0057] The hollow silica particles preferably contain one or more metals M selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba. When the hollow silica particles contain metal M, it acts as a flux during firing, reducing the specific surface area and the dielectric tangent.

[0058] In the production of raw hollow silica particles, the metal M is incorporated between the reaction step and the washing step. For example, in the reaction step, a metal salt of the metal M is added to a reaction solution in forming a silica shell, or the hollow silica precursor is washed with a solution containing a metal ion of the metal M before sintering, whereby the metal M can be incorporated into the raw hollow silica particles.

[0059] The concentration of metal M contained in the raw hollow silica particles is preferably 50 mass ppm or more and 1 mass % or less. If the total concentration of metal M is 50 mass ppm or more, the flux effect during firing promotes condensation of bonded silanol groups, and the remaining silanol groups can be reduced, so that the dielectric loss tangent can be reduced. If the concentration of metal M is too high, the amount of components that react with silica to become silicate increases, and the hygroscopicity of the hollow silica particles may deteriorate, so it is preferable to contain it at 1 mass % or less. The concentration of metal M is more preferably 100 mass ppm or more, more preferably 150 mass ppm or more, and is preferably 1 mass % or less, preferably 5000 mass ppm or less, and most preferably 1000 mass ppm or less.

[0060] The metal M can be measured by adding perchloric acid and hydrofluoric acid to hollow silica particles, igniting them to remove the main component silicon, and then measuring it by ICP atomic emission spectrometry. Furthermore, when an alkali metal silicate is used as the silica raw material, the shell layer of the resulting hollow silica particles contains less carbon (C) components derived from the raw material, compared to when a silicon alkoxide is used as the silica raw material.

[0061] The hollow silica particles preferably have a viscosity of 20,000 mPa·s or less when a kneaded product containing the hollow silica particles is measured by the following measurement method. (Measurement method) The particle density measured by a dry pycnometer using argon gas was defined as A (g / cm 3 6 parts by mass of boiled linseed oil and 6 parts by mass of hollow silica particles (6×A / 2.2) were mixed and kneaded at 2000 rpm for 3 minutes. The kneaded product was then subjected to a shear rate of 1 s using a rotational rheometer. -1 The measurement is carried out for 30 seconds, and the viscosity at the 30 second point is calculated.

[0062] The shear rate of the kneaded material measured by the above measurement method is 1s -1When the viscosity at 20000mPa·s is 20000mPa·s or less, the amount of solvent added during molding and film formation of the resin composition containing hollow silica particles can be reduced, the drying speed can be increased, and productivity can be improved. In addition, if the product of density and specific surface area according to the particle size of the silica powder becomes large, the viscosity tends to increase when added to the resin composition, but the hollow silica particles have a small product of density and specific surface area, so the increase in viscosity of the resin composition can be suppressed. The viscosity of the kneaded product is more preferably 8000mPa·s or less, even more preferably 5000mPa·s or less, and most preferably 4000mPa·s or less. The shear rate of the kneaded material is 1s -1 The lower the viscosity at , the more improved the coatability of the resin composition and the more improved the productivity, so there is no particular restriction on the lower limit.

[0063] (Method of manufacturing hollow silica particles) The hollow silica particles used in the present invention (surface-modified hollow silica particles treated with a silane coupling agent) are obtained by treating the surfaces of raw material hollow silica particles with the above-mentioned silane coupling agent.

[0064] The raw hollow silica particles may be obtained by production, or commercially available hollow silica particles may be used. When producing raw hollow silica particles, they can be produced, for example, by the method described in WO 2019 / 131658. The above-mentioned physical properties of the hollow silica particles used in the present invention are almost the same as those of the raw material hollow silica particles.

[0065] The method of treating raw hollow silica particles with silane coupling agent can be carried out by a conventional method, for example, a dry method of spraying silane coupling agent on raw hollow silica particles, a wet method of dispersing raw hollow silica particles in a solvent, and then adding silane coupling agent to react, etc. From the viewpoint of performing uniform treatment, the wet treatment method is preferred.

[0066] The hollow silica particles surface-treated with a silane coupling agent are preferably contained in the fluororesin composition in an amount of 10 to 60% by volume, more preferably 30 to 50% by volume. If the content of the hollow silica particles is 10% by volume or more, the dielectric tangent can be reduced, and if it is 60% by volume or less, a decrease in durability and a deterioration in dielectric constant can be prevented.

[0067] <Fluororesin> Fluorine resin has a lower dielectric tangent than other resins, so it is used as the main resin for insulation materials, etc. Examples of the fluororesin used in the fluororesin composition of the present invention include tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-fluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer (THV), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, ethylene-chlorotrifluoroethylene copolymer, modified polytetrafluoroethylene, etc. One type of fluororesin may be used alone, or two or more types may be used in combination.

[0068] Examples of modified polytetrafluoroethylene include (i) tetrafluoroethylene (hereinafter also referred to as "TFE") copolymerized with a trace amount of CH2=CH(CF2)4F or CF2=CFOCF3, (ii) the above (i) further copolymerized with a trace amount of an adhesive functional group-containing monomer, (iii) TFE copolymerized with a trace amount of an adhesive functional group-containing monomer, (iv) polytetrafluoroethylene into which an adhesive functional group has been introduced by plasma treatment or the like, and (v) the above (i) into which an adhesive functional group has been introduced by plasma treatment or the like.

[0069] Among these, a thermoplastic fluororesin having a melting point of 260 to 400°C is more preferable because it has better electrical properties and heat resistance, and even after being formed into a sheet, it has better electrical properties and heat resistance. When the melting point of the fluororesin is equal to or higher than the lower limit of the above range, it has excellent heat resistance, and when it is equal to or lower than the upper limit of the above range, it has excellent melt moldability. Examples of fluorine-containing polymers that can be melt molded include tetrafluoroethylene-fluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride, polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer, modified polytetrafluoroethylene, etc. In addition, polytetrafluoroethylene can be used as long as it exhibits melt fluidity.

[0070] From the viewpoints of heat resistance and melt moldability, the melting point of the fluororesin is more preferably 260 to 380°C, with the lower limit being particularly preferably 280°C or higher and most preferably 295°C or higher, and the upper limit being particularly preferably 320°C or lower and most preferably 310°C or lower. The melting point of the fluororesin can be adjusted by the type, content, molecular weight, etc. of the units constituting the fluororesin.

[0071] Further, the fluororesin is more preferably a thermoplastic fluororesin having a tetraethylene group and at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxyl group, an epoxy group, an amide group, an amino group, an isocyanate group, a fluoroformyl group, and an acid anhydride residue as an adhesive functional group. The fluororesin having a tetraethylene group provides excellent heat resistance and electrical properties. Furthermore, the fluororesin has an adhesive functional group, providing excellent adhesion to hollow silica particles and preventing the hollow silica particles from being separated from the resin composition. The functional group may be contained in a unit in the fluororesin or in a terminal group of the main chain of the fluororesin.

[0072] The carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and is preferably a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH2), an acid anhydride residue (-C(O)OC(O)-), an imide residue (-C(O)NHC(O)-, etc.) or a carbonate group (-OC(O)O-).

[0073] When the fluororesin has a carbonyl group-containing group, the number of carbonyl group-containing groups in the fluororesin is 1×10 6 The number of carbonyl-containing groups per unit is preferably 10 to 5000, more preferably 50 to 4000, and even more preferably 100 to 2000. In this case, the peel strength of the resulting thin film is likely to be improved. In addition, the linear expansion coefficient of the resulting thin film can be reduced, and wrinkles can be more reliably prevented from occurring. The number of carbonyl-containing groups in the fluororesin can be quantified by the composition of the polymer or the method described in WO2020 / 145133.

[0074] The melt flow rate (hereinafter referred to as "MFR") of the fluororesin at a temperature at least 20°C higher than the melting point of the fluororesin (usually 372°C) is preferably 0.1 to 1000 g / 10 min, more preferably 0.5 to 100 g / 10 min, further preferably 1 to 30 g / 10 min, and particularly preferably 5 to 20 g / 10 min. When the MFR is equal to or greater than the lower limit of the above range, the fluororesin has excellent moldability, and therefore the molded article formed from the fluororesin composition of the present invention has excellent surface smoothness and appearance.When the MFR is equal to or less than the upper limit of the above range, the fluororesin has excellent mechanical strength, and therefore the molded article formed from the fluororesin composition of the present invention has excellent mechanical strength.

[0075] MFR is a measure of the molecular weight of a fluororesin; a larger MFR indicates a smaller molecular weight, and a smaller MFR indicates a larger molecular weight. The molecular weight of a fluororesin, and therefore the MFR, can be adjusted by the manufacturing conditions of the fluororesin. For example, shortening the polymerization time during monomer polymerization tends to increase the MFR.

[0076] The fluororesin content in the fluororesin composition of the present invention is preferably 10 to 50 mass%, more preferably 25 to 40 mass%. When the fluororesin content is 10 mass% or more, the relative dielectric constant and the dielectric loss tangent can be reduced, and when it is 50 mass% or less, the fluororesin is easily dispersed uniformly and has excellent mechanical strength.

[0077] <Fluorosurfactant> The fluororesin composition of the present invention contains a fluorosurfactant, which improves dispersibility and compatibility due to a decrease in surface free energy, prevents poor dispersion, and improves moldability.

[0078] Examples of commercially available fluorine-based surfactants include perfluoroalkyl group-containing Ftergent M series, Ftergent F209, Ftergent 222F, Ftergent 208G, Ftergent 218GL, Ftergent 710FL, Ftergent 710FM, Ftergent 710FS, Ftergent 730FL, Ftergent 730LM (manufactured by Neos Corporation), Megafac series such as Megafac F-553, Megafac F-555, Megafac F-556, Megafac F-557, Megafac F-559, Megafac F-562, Megafac F-565 (manufactured by DIC Corporation), Unidyne series such as Unidyne DS-403N (manufactured by Daikin Industries, Ltd.), etc. These may be used alone or in combination of two or more. Among these, FTERGENT 710FL, FTERGENT 710FM and FTERGENT 710FS, which are surfactants in which the fluorine-containing group has a branched structure and three-dimensional bulkiness, are preferred.

[0079] The content of the fluororesin composition of the present invention is preferably 1 to 10 parts by mass of the fluororesin relative to 100 parts by mass of the fluororesin. When the content of the fluorosurfactant is 1 part by mass or more relative to 100 parts by mass of the fluororesin, the dispersibility and compatibility of the hollow silica particles are improved, and moldability can be improved. When the content of the fluorosurfactant is 10 parts by mass or less relative to 100 parts by mass of the fluororesin, the dielectric constant and dielectric loss tangent can be further reduced. The content of the fluorosurfactant is more preferably 2 parts by mass or more, more preferably 3 parts by mass or more, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less.

[0080] <Other ingredients> The fluororesin composition of the present invention may further contain other materials within the scope of not impairing the effects of the present invention, such as a dispersing agent, a thixotropic agent, an antifoaming agent, an inorganic filler other than silica, a reactive alkoxysilane, a dehydrating agent, a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, an antistatic agent, a brightening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, a viscosity adjusting agent, and a flame retardant. These other materials may or may not be soluble in the resin composition.

[0081] <Method of producing fluororesin composition> The fluororesin composition of the present invention is obtained by mixing the hollow silica particles surface-modified with the silane coupling agent, the fluororesin, and a fluorosurfactant. Since the fluororesin is usually in a powder form, it is preferable to prepare the composition by dispersing it in a solvent.

[0082] It is preferable to use a solvent that is liquid at 25°C. The boiling point of the solvent is preferably 125 to 250° C. Within this range, when the solvent is evaporated from the fluororesin composition, the composition flows highly and packs densely, and as a result, a dense fluororesin layer is easily formed.

[0083] The solvent is preferably an aprotic polar medium.

[0084] Specific examples of the solvent include water, 1-propanol, 2-propanol (IPA), 1-butanol, 1-methoxy-2-propanol, N,N-dimethylformamide, N,N-dimethylacetamide, methyl ethyl ketone, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, cyclohexanone, cyclopentanone, dimethyl sulfoxide, diethyl ether, dioxane, butyl acetate, methyl isopropyl ketone, cyclopentanone, cyclohexanone, ethylene glycol monoisopropyl ether, and cellosolve (methyl cellosolve, ethyl cellosolve, etc.). The solvent may be used alone or in combination of two or more.

[0085] The fluororesin composition of the present invention has excellent properties such as weather resistance, flame retardancy, heat resistance, antifouling properties, smoothness, chemical resistance, etc. Therefore, the fluororesin can be used as materials for articles exposed to outdoor environments, printed wiring boards, carriers and bottles for semiconductors, chemical piping and piping joints, hydraulic seal rings for automatic transmissions and power steering mechanisms, accelerator cables, and cables for tranny openers, sliding parts, weather-resistant topcoats, and protective coating materials, and in particular, insulating films formed from the fluororesin composition of the present invention can be suitably used for printed wiring boards.

[0086] (Processing boards and printed wiring boards) The present invention includes a treated substrate comprising a substrate and a thin film formed on the surface of the substrate from the above-mentioned fluororesin composition. The thickness of the thin film in the treated substrate is 10 to 100 μm. If the thickness is 10 μm or more, durability and mechanical strength are improved, and if it is 100 μm or less, mountability is excellent. The thickness of the thin film is preferably 15 μm or more, more preferably 20 μm or more, and preferably 95 μm or less, more preferably 90 μm or less.

[0087] Examples of the substrate include metal foils such as copper foil, aluminum foil, iron, stainless steel, brass, nickel, zinc, titanium, and alloys of these metals.

[0088] The present invention also includes a method for producing a treated substrate, which comprises treating the surface of a substrate with the above-mentioned fluororesin composition to form a thin film. The thin film is formed, for example, by applying a slurry-like fluororesin composition to the substrate by a doctor blade method. The thickness of the thin film is preferably 10 μm or more from the viewpoints of durability and mechanical strength, and preferably 100 μm or less from the viewpoint of mountability. The thickness of the thin film is preferably 15 μm or more, more preferably 20 μm or more, and is preferably 95 μm or less, more preferably 90 μm or less.

[0089] After forming a layer of the fluororesin composition on the substrate, it is preferable to heat it. The heating temperature is equal to or higher than the melting point of the fluororesin, and is preferably 300 to 400°C, and more preferably 350 to 370°C. The heating time is preferably 20 minutes to 2 hours, and more preferably 30 minutes to 2 hours, from the viewpoint of melting and productivity. The heating is preferably performed in a nitrogen atmosphere.

[0090] The present invention also includes a printed wiring board comprising a metal foil substrate and a thin film formed from the above-mentioned fluororesin composition disposed on the surface of the metal foil substrate.

[0091] Examples of the metal foil include metal foils made of metals such as copper, aluminum, solder, tin, nickel, palladium, gold, silver, alumina, tungsten, and molybdenum, and copper foil is preferred. As the copper foil, a foil made of a single metal, copper, or a foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0092] The thickness of the thin film formed from the fluororesin composition in the printed wiring board is preferably 10 to 100 μm. When the film thickness is 10 μm or more, durability and mechanical strength are improved, and when it is 100 μm or less, dimensional change during thermal expansion is small, and warping of the present sheet and a laminate (such as a copper-clad laminate) in which the present sheet is laminated with other materials can be suppressed. The thickness of the thin film is preferably 15 μm or more, more preferably 20 μm or more, and is preferably 95 μm or less, more preferably 90 μm or less.

[0093] The present invention also includes a method for producing a printed wiring board by forming a layer of the above-mentioned fluororesin composition on the surface of a copper foil substrate and heating the same, preferably in a nitrogen atmosphere.

[0094] The heating temperature is equal to or higher than the melting point of the fluororesin, and is preferably 300 to 400° C., and more preferably 350 to 370° C. The heating time is preferably 20 minutes to 2 hours, and more preferably 30 minutes to 2 hours, from the viewpoint of melting and productivity.

[0095] The treated substrate and printed wiring board of the present invention preferably have a relative dielectric constant of 2.0 to 3.5 at a frequency of 10 GHz when copper foil is used as the metal foil. When the relative dielectric constant of the treated substrate and printed wiring board at a frequency of 10 GHz is within the above range, the electrical properties are excellent, and the use in electronic devices, communication devices, etc. is expected. The lower limit of the relative dielectric constant is more preferably 2.2 or more, and even more preferably 2.3 or more, and the upper limit is more preferably 3.2 or less, and even more preferably 3.0 or less.

[0096] The relative dielectric constant can be measured at 25° C. and 10 GHz using a network analyzer (for example, E8362B manufactured by Keysight Corporation) in accordance with the method specified in JISR 1641:2007.

[0097] In addition, when copper foil is used as the metal foil, the dielectric loss tangent of the treated substrate and the printed wiring board is preferably 0.01 or less at a frequency of 10 GHz. When the dielectric loss tangent of the treated substrate and the printed wiring board at a frequency of 10 GHz is within the above range, the electrical characteristics are excellent, so that it is expected to be used in electronic devices, communication devices, etc. The dielectric loss tangent is more preferably 0.008 or less, and even more preferably 0.0065 or less. The smaller the dielectric loss tangent, the more the transmission loss of the circuit is suppressed, so the lower limit is not particularly limited.

[0098] The dielectric loss tangent can be measured at 25° C. and 10 GHz using a split post dielectric resonator (SPDR) (for example, manufactured by Agilent Technologies) in accordance with the method specified in JIS R 1641:2007.

[0099] In addition, the average linear expansion coefficient of the treated substrate and the printed wiring board when copper foil is used as the metal foil is preferably 10 to 50 ppm / °C. When the average linear expansion coefficient is in the above range, it is close to the thermal expansion coefficient of copper foil that is widely used as a base material, and therefore the electrical properties are excellent. The average linear expansion coefficient is more preferably 12 ppm / °C or more, even more preferably 15 ppm / °C or more, and more preferably 40 ppm / °C or less, even more preferably 30 ppm / °C or less.

[0100] The average linear expansion coefficient is determined by heating the treated substrate with a load of 5 N at a temperature increase rate of 2°C / min using a thermomechanical analyzer (e.g., Shimadzu Corporation's "TMA-60"), measuring the dimensional change of the sample from 30°C to 150°C, and calculating the average.

[0101] In addition, when copper foil is used as the metal foil, the treated substrate and the copper-clad laminate preferably have a water absorption rate (amount of moisture adsorbed) of 1.5% or less. If the water absorption rate is 1.5% or less, the amount of moisture absorbed when a thin film is formed by treating the resin composition is reduced, and the dielectric loss of the resin composition can be suppressed.

[0102] The water absorption rate is measured based on the water absorption test in the test method for copper-clad laminates for printed wiring boards in JIC C 6481. The cut surfaces of the treated substrate or printed wiring board are smoothed using abrasive paper of P240 or higher specified in JIS R 6252, and left in a thermostatic chamber maintained at 50±2°C for 24±1 hours as a pretreatment. The treated sample is cooled to 25°C in a desiccator and its mass is weighed. Next, it is immersed in a water absorption container containing distilled water at 23±0.5°C for 24±1 hours, then removed, thoroughly wiped with a dry, clean cloth, the surface dust removed, and within 1 minute placed in a weighing bottle, sealed, and weighed after absorbing water. From the obtained results, the water absorption rate W is calculated using the following formula. A Calculate the percentage. W A =W1-W0 / W0×100 W0: Mass of the sample before water absorption (g) W1: Mass of the sample after absorbing water (g)

[0103] In addition, when a copper foil is used as the metal foil, the tensile strength of the treated substrate and the printed wiring board is preferably 11 MPa or more. When the tensile strength is in the above range, the mechanical strength can be ensured. The tensile strength is more preferably 15 MPa or more, even more preferably 17 MPa or more, and more preferably 100 MPa or less, even more preferably 50 MPa or less.

[0104] The tensile strength can be determined by referring to JIS K7127 Plastics - Tensile Property Test Method using an autograph (AGX-V) manufactured by Shimadzu Corporation. EXAMPLES

[0105] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. In the following description, the same components are used as common components. Examples 1 to 3 are working examples, and Examples 4 to 8 are comparative examples.

[0106] (Production Example 1) Polymer X, which is a TFE-based polymer, was produced by the procedure described in paragraph

[0123] of WO 2016 / 017801 using 5-norbornene-2,3-dicarboxylic anhydride (also known as himic anhydride (NAH), manufactured by Hitachi Chemical Co., Ltd.), tetrafluoroethylene (TFE), and PPVE (CF2=CFO(CF2)3F, manufactured by AGC Co., Ltd.) as monomers. The copolymerization composition of polymer X was NAH unit / TFE unit / PPVE unit=0.1 / 97.9 / 2.0 (mol%). The melting point of polymer X was 300° C., the MFR was 17.6 g / 10 min, the relative dielectric constant (10 GHz) was 2.0, and the storage modulus at 260° C. was 1.1 MPa. The obtained polymer X was granular, and the average particle size was 1554 μm. Next, the polymer X was pulverized using a jet mill (Seishin Enterprise Co., Ltd., single track jet mill FS-4 type) under conditions of a pulverization pressure of 0.5 MPa and a processing rate of 1 kg / hr to obtain a resin powder P-1. The resin powder P-1 had an average particle size D50 of 2.58 μm and a coarse particle size D90 of 7.1 μm.

[0107] (Example 1) 1. Preparation of fluororesin composition Raw material hollow silica particles (AGC, average particle size 700 nm, Ar specific gravity 0.61 g / cm 3 ) was dispersed in IPA / toluene, trifluoropropyltrimethoxysilane and ethylenediamine were added, and the mixture was heated and stirred at 80° C. for 4 hours. The obtained silica was filtered and washed using a membrane filter with an opening of 0.45 μm to obtain trifluoropropyltrimethoxysilane-treated hollow silica particles. Next, 30 g of resin powder P-1, 3 g of a nonionic fluorosurfactant (Neos Corporation, Ftergent 710FL), 30 g of N-methyl-2-pyrrolidone, and 9 g of the trifluoropropyltrimethoxysilane-treated hollow silica particles prepared above were placed in a pot and mixed at 2000 rpm for 3 minutes or more using a Thinky Corporation rotation / revolution type mixer "Awatori Rentaro" to uniformly disperse the mixture, thereby obtaining a fluororesin composition.

[0108] 2. Preparation of Double-sided Copper-clad Laminates The fluororesin composition was applied to a surface of 18 μm thick copper foil (TQ-M4-VSP, manufactured by Mitsui Mining & Smelting Co., Ltd.) to a thickness of 200 μm by doctor blade method. This was heated at 80° C. for 10 minutes to dry the solvent (primary drying), and then heated and dried at 350° C. for 2 hours in a nitrogen atmosphere to form a substrate. This resulted in a single-sided copper-clad laminate in which copper foil was laminated on one surface of the substrate. Further, the same copper foil as above was laminated on the substrate side surface of the single-sided copper-clad laminate, and pressed for 60 minutes in a vacuum hot press at a temperature of 330° C. under a pressure of 8 MPa to obtain a double-sided copper-clad laminate. In the obtained composite CCL substrate, the ratio of the volume of silica to the total volume of polymer X and silica was 50 volume %, the ratio of the volume of polymer X and silica to the total volume of the substrate was 100 volume %, the thickness of the fluororesin thin film was 90 μm, and the thickness of the substrate was 126 μm.

[0109] (Examples 2 to 5) A double-sided copper-clad laminate was produced in the same manner as in Example 1, except that the composition of the silica particles, the type of silane coupling agent, the type of surfactant, the type of resin, etc. were changed as shown in Table 1.

[0110] (Examples 6 to 8) A double-sided copper-clad laminate was produced in the same manner as in Example 1, except that the composition of the silica particles, the type of silane coupling agent, the type of surfactant, the type of resin, etc. were changed as shown in Table 1.

[0111] <Evaluation> (aggregated state) The resin composition was mixed again for 3 minutes at 2000 rpm using a rotation-revolution mixer "Awatori Rentaro" manufactured by Thinky Corporation, and after leaving it to stand for one day, the dispersion was visually observed for the presence of aggregates at the air-liquid interface or bottom. When no agglomerates were present, the sample was rated as "no lumps", and when agglomerates were observed, the sample was rated as "lumps".

[0112] (Moldability) The moldability was evaluated by applying the resin composition to the surface of a copper foil, drying it with a solvent at 80° C. for 10 minutes (primary drying), and visually inspecting the state to see whether or not there were any cracks. Those in which no cracks were observed were rated as "good", and those in which cracks were observed were rated as "poor".

[0113] (Tensile test) The tensile strength was measured with an autograph (AGX-V) manufactured by Shimadzu Corporation, in accordance with JIS K7127 Plastics - Testing methods for tensile properties. A test piece measuring 130 mm in length and 2 mm in width was cut out from the double-sided copper-clad laminate. The test piece was held at a position 30 mm from one end in the longitudinal direction by driving the pneumatically operated gripping jaws of an autograph. A 5 kN test piece gripper was used, and the test piece was pulled by applying a load at a constant crosshead movement speed of 100 mm / sec. The tensile force at the time of break was read, and the tensile strength (MPa) was obtained by dividing this by the cross-sectional area (thickness x width) of the test piece. Ten test pieces were prepared, and this test was performed 10 times, with the average value being taken as the tensile strength (MPa).

[0114] (Water absorption rate) The amount of moisture adsorption was measured with reference to the water absorption test in the test methods for copper-clad laminates for printed wiring boards in JIC C 6481. The double-sided copper-clad laminate was cut into pieces of 50±1 mm in length and width with the original thickness, and the cut surfaces were smoothed with abrasive paper of P240 or higher specified in JIS R 6252. As a pretreatment, the test pieces were left in a thermostatic chamber maintained at 50±2°C for 24±1 hours. After treatment, the samples were cooled to 25°C in a desiccator and their mass was accurately measured to the nearest 1 mg. Next, the samples were immersed in a water absorption container containing distilled water at 23±0.5°C for 24±1 hours, then removed, thoroughly wiped with a dry clean cloth, dusted off the surface with a feather or brush, and placed in a weighing bottle within 1 minute, sealed, and weighed to the nearest 1 mg after absorbing water. The water absorption rate W was calculated using the following formula: A (%) was calculated. W A =W1-W0 / W0×100 W0: Mass of the sample before water absorption (g) W1: Mass of the sample after absorbing water (g)

[0115] (Dielectric tangent) The double-sided copper-clad laminate was immersed overnight in an aqueous solution of iron (III) chloride hexahydrate to remove the copper foil, thereby obtaining a test substrate. The dielectric loss tangent of the test substrate was measured at 25° C. and 10 GHz using a split post dielectric resonator (SPDR) (manufactured by Agilent Technologies) in accordance with the method specified in JIS R 1641:2007.

[0116] (Dielectric constant) The double-sided copper-clad laminate was immersed overnight in an aqueous solution of iron (III) chloride hexahydrate to remove the copper foil, thereby obtaining a test substrate. The relative dielectric constant of the test substrate was measured at 25° C. and 10 GHz using a network analyzer (E8362B manufactured by Keysight Corporation) in accordance with the method specified in JISR 1641:2007.

[0117] [Table 1]

[0118] As can be seen from the results in Table 1, the fluororesin compositions prepared in Examples 1 to 3 had excellent moldability, high mechanical strength when formed into a thin film, and excellent moisture absorption, and the dielectric tangent and relative dielectric constant of the double-sided copper-clad laminate were also sufficiently low. In contrast, the resin compositions prepared in Examples 4 to 8 showed cracks when applied to copper foil and dried, and had poor moldability. The mechanical strength of Examples 4 to 5 when made into a thin film was lower than that of Examples 1 to 3. For Examples 6 to 8, streaks appeared after application and cracks occurred after primary drying, so film evaluation was not performed.

Claims

1. The fluororesin composition comprises amorphous hollow silica particles having a surface treated with a fluorine-containing silane coupling agent or a fluorine-containing silane coupling agent and an amino group-containing silane coupling agent, the shell thickness being 10 to 50 nm, and the average particle size being 50 nm or more and less than 10 μm; a fluororesin; and a fluorosurfactant.

2. 2. The fluororesin composition according to claim 1, wherein the content of the hollow silica particles is 10 to 60% by volume.

3. 3. The fluororesin composition according to claim 1, wherein the fluororesin composition contains 1 to 10 parts by mass of the fluorosurfactant per 100 parts by mass of the fluororesin.

4. 3. The fluororesin composition according to claim 1, wherein the fluorine-containing silane coupling agent is either trifluoropropyltrimethoxysilane or trifluoropropyltriethoxysilane, and the amino group-containing silane coupling agent is either 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane.

5. 3. The fluororesin composition according to claim 1, wherein the fluororesin is a thermoplastic fluororesin having a melting point of 260 to 400°C.

6. 3. The fluororesin composition according to claim 1, wherein the fluororesin is a thermoplastic fluororesin having a tetraethylene group and further having at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, an amide group, an amino group, an isocyanate group, a fluoroformyl group, and an acid anhydride residue.

7. The fluororesin composition according to claim 1 or 2, which is for use in printed wiring boards.

8. An insulating film formed from the fluororesin composition according to claim 1 or 2.

9. A treated substrate comprising a substrate and a thin film having a thickness of 10 to 100 μm, which is formed from the fluororesin composition according to claim 1 or 2 and disposed on the surface of the substrate.

10. A printed wiring board comprising a metal foil substrate and a thin film formed from the fluororesin composition according to claim 1 or 2, disposed on the surface of the metal foil substrate.

11. The printed wiring board according to claim 10, wherein the metal foil substrate is a copper foil substrate.

12. The printed wiring board according to claim 10, wherein the thin film has a thickness of 10 to 100 μm.

13. The method for manufacturing a printed wiring board according to claim 10, A method for producing a printed wiring board, which comprises forming a layer of the fluororesin composition according to claim 1 or 2 on the surface of a metal foil substrate and heating the resulting substrate.