Styrene-based resin composition, film, and transparent antenna

Abstract

To provide a styrene-based resin composition for transparent antennas that exhibits superior transparency and low dielectric characteristics.SOLUTION: The present invention provides a styrene-based resin composition for transparent antennas, the composition comprising a styrene-based polymer having 30 to 100 mass% of styrene monomer units.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a styrene-based resin composition, a film, and a transparent antenna. [Background technology]

[0002] In recent years, the number of devices requiring communication has increased, and antennas for transmitting and receiving signals are needed in various locations. In particular, there is a demand for transparent antennas in which an antenna pattern such as fine metal wiring is formed on a transparent film (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-170404 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a demand for various resin compositions that have excellent low dielectric properties for radio wave transmission as materials for use in transparent antenna films.

[0005] The present invention has been made in view of the above problems, and provides a styrene-based resin composition for transparent antennas which has excellent transparency and low dielectric properties. [Means for solving the problem]

[0006] As a result of intensive investigations to solve the above-mentioned problems, the present inventors have found that a styrene-based resin composition containing a specific styrene-based polymer has excellent transparency and low dielectric properties and can solve the above-mentioned problems, thereby completing the present invention.

[0007] According to the present invention, the following inventions are provided. [1] A styrene-based resin composition for a transparent antenna, comprising a styrene-based polymer having 30 to 100% by mass of a styrene-based monomer unit. [2] The styrene-based resin composition according to [1], wherein the styrene-based polymer contains 1 to 50 mass % of a monomer unit A other than a styrene-based monomer unit. [3] The styrene-based resin composition according to [2], wherein the monomer unit A comprises at least one selected from the group consisting of a (meth)acrylic acid unit and a (meth)acrylic acid ester unit. [4] The styrene resin composition according to any one of [1] to [3], which has an MFR retention of 90 to 110% after exposure to an environment of 80°C and 90% RH for 168 hours. [5] The styrene-based resin composition according to any one of [1] to [4], wherein a molded article obtained by molding the styrene-based resin composition has a dielectric loss tangent of less than 0.0050 at a measurement frequency of 24 GHz. [6] A transparent antenna film, comprising a layer made of the styrene resin composition according to any one of [1] to [5]. [7] A transparent antenna comprising the film described in [6]. [Effects of the Invention]

[0008] The styrene-based resin composition of the present invention has excellent transparency and low dielectric properties and can be used for films for transparent antennas. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently. Furthermore, in the following embodiments, elements not specified in the claims are optional elements and can be omitted. Any number of "0"s (for example, one or two) may be added to the end of numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0010] 1. Styrene-based resin composition The styrene-based resin composition according to one embodiment of the present invention includes a styrene-based polymer having 30 to 100% by mass of styrene-based monomer units. Such a styrene-based resin composition has excellent low dielectric properties and high transparency, and therefore can be used as a styrene-based resin composition for transparent antennas, and a molded product thereof can be used as a film or other component that constitutes a part of a transparent antenna.

[0011] The styrene polymer contains 30 to 100 mass% of styrene monomer units, preferably 50 to 100 mass%, more preferably 50 to 99 mass%, and even more preferably 90 to 96 mass%, based on 100 mass% of the styrene polymer. When the content is within this range, the styrene polymer exhibits excellent low dielectric properties. Specifically, the content of the styrene monomer units in the styrene polymer is, for example, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 mass%, and may be within a range between any two of the values ​​exemplified here.

[0012] The styrene-based monomer unit is a structural unit derived from a styrene-based monomer. Examples of the styrene-based monomer include styrene; α-methylstyrene; alkylated styrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, and p-tert-butylstyrene; halogenated styrenes such as p-chlorostyrene; and alkoxylated styrenes such as p-methoxystyrene. These can be used alone or in combination of two or more. The styrene-based monomer is preferably styrene, α-methylstyrene, or an alkylated styrene, and more preferably styrene.

[0013] The styrene polymer may contain, for example, 1 to 50 mass%, preferably 2 to 20 mass%, and more preferably 4 to 10 mass% of monomer units A other than styrene monomer units, relative to 100 mass% of the styrene polymer. Specific examples of the content of monomer units A in the styrene polymer include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, and 50 mass%, and may be within a range between any two of the values ​​exemplified here.

[0014] The monomer unit A other than the styrene-based monomer unit is a structural unit derived from a monomer A copolymerizable with a styrene-based monomer. The monomer A includes, for example, one or more units selected from the group consisting of (meth)acrylic acid and (meth)acrylic acid esters, and preferably includes (meth)acrylic acid. That is, the monomer unit A includes, for example, one or more units selected from the group consisting of (meth)acrylic acid units and (meth)acrylic acid ester units, and preferably includes a (meth)acrylic acid unit.

[0015] The (meth)acrylic acid is acrylic acid or methacrylic acid (MAA), preferably methacrylic acid. The (meth)acrylic acid ester is an acrylic acid ester or a methacrylic acid ester. Examples of (meth)acrylic acid esters include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; (meth)acrylic acid aryl esters such as phenyl (meth)acrylate and benzyl (meth)acrylate; (meth)acrylic acid cycloalkyl esters such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and adamantyl (meth)acrylate; glycidyl (meth)acrylate; and dicyclopentadienyl (meth)acrylate. These can be used alone or in combination of two or more. The (meth)acrylic acid ester is preferably a (meth)acrylic acid alkyl ester, more preferably a methacrylic acid alkyl ester, and even more preferably methyl methacrylate (MMA).

[0016] In one embodiment, the styrene-based polymer may be a styrene homopolymer having 100% by mass of structural units derived from styrene. Such a styrene homopolymer may have a structure such as an atactic structure, an isotactic structure, or a syndiotactic structure, and preferably has an atactic structure.

[0017] In one embodiment, the styrene-based polymer may be a styrene-(meth)acrylic acid copolymer or a styrene-methyl(meth)acrylate copolymer.

[0018] The styrene-based resin composition preferably contains 80% by mass or more, more preferably 90% by mass or more, of a styrene-based polymer relative to 100% by mass of the styrene-based resin composition. When the content is within this range, the composition exhibits excellent low dielectric properties and dimensional stability. The content of the styrene-based polymer relative to 100% by mass of the styrene-based resin composition is, for example, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100% by mass, and may be within a range between any two of the values ​​exemplified here.

[0019] The styrene-based resin composition may contain other polymers besides the styrene-based polymer, such as polyphenylene ether resins, polybutylene terephthalate resins, and poly(meth)acrylate resins, as long as the effects of the present invention are not impaired.

[0020] The styrene-based resin composition preferably contains, as the styrene-based polymer, a homopolymer of a styrene-based monomer and / or a random copolymer of a styrene-based monomer and another monomer. The styrene-based resin composition may contain a styrene-based block copolymer, but the content of the styrene-based block copolymer is, for example, less than 20% by mass, preferably 10% by mass or less, and more preferably no styrene-based block copolymer is contained.

[0021] The styrene-based resin composition may contain additives within the range that does not impair the effects of the present invention. Examples of additives include flame retardants, flame retardant aids, antioxidants, antiaging agents, impact modifiers, release agents, ultraviolet absorbers, antistatic agents, antifogging agents, lubricants / antiblocking agents, flow improvers, compatibilizers, plasticizers, dispersants, antibacterial agents, etc., and additives commonly used in styrene-based resin compositions can be blended.

[0022] <Characteristics of styrene-based resin compositions> The styrene-based resin composition preferably exhibits an MFR (melt flow rate) retention of 90 to 110%, more preferably 95 to 105%, after 168 hours of exposure to an environment of 80°C and 90% RH. The MFR retention represents the ratio of the MFR (MFR2) after the exposure test to the MFR (MFR1) measured before the exposure test [MFR2 / MFR1 × 100 (%)]. MFR measurement is performed in accordance with JIS K-7210 under conditions of a 49 N load and a predetermined temperature (e.g., 200 to 250°C). Resin compositions containing resins tend to have a higher MFR when the resin decomposes due to environmental factors such as heat, resulting in a lower molecular weight. When the MFR retention is within a predetermined range (e.g., 110% or less), the resin is less likely to decompose into smaller molecules due to decomposition, and the composition has high environmental resistance.

[0023] The dielectric loss tangent of a molded article obtained by molding a styrene-based resin composition at a measurement frequency of 24 GHz is preferably less than 0.0050, more preferably 0.0025 or less, and even more preferably 0.0015 or less. Within this range, low radio wave propagation loss can be expected. The dielectric loss tangent does not need to have a lower limit, but is, for example, 0.0001 or more, such as 0.0010 or more. The dielectric loss tangent may be, for example, 0.0001, 0.0005, 0.0010, 0.0015, 0.0020, 0.0025, 0.0030, 0.0035, 0.0040, or 0.0049, or may be within a range between any two of the values ​​exemplified here.

[0024] The dielectric constant of a molded article obtained by molding a styrene-based resin composition at a measurement frequency of 24 GHz is preferably 2.70 or less, more preferably 2.45 or less, even more preferably 2.40 or less, and particularly preferably 2.20 or less. Within such a range, low radio wave propagation loss can be expected. The dielectric constant does not need to have a lower limit, but may be, for example, 1.00 or more, or even 2.00 or more. Specific examples of the dielectric constant include 0.50, 1.00, 1.50, 2.00, 2.10, 2.20, 2.30, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, and 2.70, and may be within a range between any two of the values ​​exemplified here.

[0025] The haze of a 0.3 mm thick molded product of the styrene resin composition, as measured by a haze meter, is preferably less than 0.9%, more preferably 0.7% or less, and even more preferably 0.5% or less. Specific examples of the haze include 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8%, and may be within a range between any two of the values ​​exemplified here.

[0026] The total light transmittance of a molded product having a thickness of 0.3 mmt obtained by molding the styrene resin composition, as measured with a haze meter, is preferably 89% or more, and more preferably 90% or more.

[0027] The water absorption of a molded article obtained by molding the styrene-based resin composition, measured in accordance with JIS K 7209, is preferably 1.0% or less, more preferably 0.2% or less, and even more preferably 0.15% or less.

[0028] The Vicat softening point of the styrene resin composition is preferably 98° C. or higher, more preferably 102° C. or higher, and even more preferably 110° C. or higher. The Vicat softening point is measured in accordance with JIS K 7206 under conditions of a load of 50 N and a heating rate of 50° C. / hr.

[0029] The methods for measuring these properties will be described later in the Examples.

[0030] 2. Method for producing styrene-based resin composition A method for producing a styrene-based resin composition according to one embodiment of the present invention includes a polymerization step of polymerizing raw material monomers containing a styrene-based monomer to produce a styrene-based polymer. The polymerization step can be carried out by a known polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization. In terms of quality and productivity, bulk polymerization and solution polymerization are preferred, and continuous polymerization is preferable. Examples of solvents that can be used include alkylbenzenes such as benzene, toluene, ethylbenzene, and xylene, ketones such as acetone and methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and cyclohexane.

[0031] The raw material monomer contains 30 to 100 mass % of a styrene-based monomer, preferably 50 to 100 mass %, more preferably 50 to 99 mass %, and even more preferably 90 to 96 mass %. Known polymerization conditions can be used as the polymerization conditions.

[0032] During the polymerization of the styrene polymer, polymerization aids such as a polymerization initiator, a chain transfer agent, a crosslinking agent, and other polymerization aids may be used as needed. The polymerization initiator is preferably a radical polymerization initiator, and examples of the polymerization initiator include known and commonly used peroxyketals such as 1,1-di(t-butylperoxy)cyclohexane, 2,2-di(t-butylperoxy)butane, 2,2-di(4,4-di-t-butylperoxycyclohexyl)propane, and 1,1-di(t-amylperoxy)cyclohexane, hydroperoxides such as cumene hydroperoxide and t-butyl hydroperoxide, alkyl peroxides such as t-amylperoxyisononanoate, and dialkyl peroxides such as t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, and di-t-hexyl peroxide. Examples of the peroxides include peroxyesters such as t-butylperoxyacetate, t-butylperoxybenzoate, and t-butylperoxyisopropyl monocarbonate; peroxycarbonates such as t-butylperoxyisopropyl carbonate and polyether tetrakis(t-butylperoxycarbonate); N,N'-azobis(cyclohexane-1-carbonitrile), N,N'-azobis(2-methylbutyronitrile), N,N'-azobis(2,4-dimethylvaleronitrile), and N,N'-azobis[2-(hydroxymethyl)propionitrile]; and these can be used alone or in combination of two or more. Examples of chain transfer agents include aliphatic mercaptans such as n-dodecyl mercaptan and tert-dodecyl mercaptan, aromatic mercaptans, thiocarboxylic acids such as thioglycolic acid and mercaptopropionic acid, polyfunctional mercaptans in which the hydroxyl group of a polyhydric alcohol such as ethylene glycol, tetraethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol, or sorbitol is esterified with thioglycolic acid or mercaptopropionic acid, pentaphenylethane, α-methylstyrene dimer, and terpinolene. Among these, aliphatic mercaptans, aromatic mercaptans, thiocarboxylic acids, and polyfunctional mercaptans are preferred because of their ease of molecular weight adjustment.

[0033] In the case of continuous polymerization, the method for producing a styrene-based resin composition may include a polymerization step, a devolatilization step, and a granulation step.

[0034] In the polymerization step, a known complete mixing tank type stirring tank or tower type reactor is used, and the polymerization reaction can be controlled by adjusting the polymerization temperature or the like so as to achieve the target molecular weight, molecular weight distribution, and reaction conversion rate.

[0035] The polymer solution containing the polymer that has left the polymerization process is transferred to the devolatilization process, where unreacted monomers and polymerization solvent are removed. The devolatilization process is composed of a vacuum devolatilization tank equipped with a heater or a devolatilization extruder equipped with a vent. The molten polymer that has left the devolatilization process is transferred to the granulation process. In the granulation process, the molten resin is extruded in the form of strands through a multi-hole die and processed into pellets using the cold cut method, the in-air hot cut method, or the underwater hot cut method.

[0036] In the method for producing a styrene-based resin composition, the additives may be added to a raw material solution before polymerization of the styrene-based polymer, or the additives may be mixed in an extruder or static mixer installed after polymerization of the styrene-based polymer and before granulation. Alternatively, the styrene-based resin composition may be produced by dry-blending pellets of the styrene-based polymer after granulation with the additives and melt-kneading the mixture. Alternatively, the additives may be melt-kneaded in advance with a small amount of the styrene-based polymer to prepare a pellet-like masterbatch, which is then dry-blended with the styrene-based polymer and then melt-kneaded to prepare the resulting mixture.

[0037] 3. Film / Transparent Antenna A film according to one embodiment of the present invention is a film comprising a layer composed of the styrene-based resin composition. The film may be composed solely of a layer composed of the styrene-based resin composition, or may further comprise a layer composed of another resin, etc. Such a film has excellent low dielectric properties and high transparency, and can therefore be used as a transparent antenna film. The transparent antenna film can be used, for example, as a transparent antenna substrate for wireless reception in the millimeter wave band, microwave band, UHF band, and VHF band.

[0038] The styrene resin composition can be used to form a film by any known method, such as extrusion molding, injection molding, or compression molding.

[0039] A transparent antenna according to one embodiment of the present invention is an antenna including a film (antenna substrate) having a layer formed from the styrene-based resin composition. The transparent antenna includes, for example, an antenna substrate and an antenna pattern. [Example]

[0040] The present invention will be described in more detail below with reference to examples, but these examples are merely illustrative and are not intended to limit the scope of the present invention.

[0041] [Preparation of Resin Composition] Resin compositions P-1 to P-9 were prepared as the resin compositions.

[0042] <<Configuration of reactor used in producing resin compositions P-1 to P-3>> The polymerization process was configured by connecting the following first to third reactors in series. First reactor: 39 L volume complete mixing reactor with agitator Second reactor: 39 L volume complete mixing reactor with agitator Third reactor: 16 L volume plug flow reactor with static mixer

[0043] <Resin composition P-1> A raw material solution consisting of 94.0 parts by mass of styrene monomer and 6.0 parts by mass of ethylbenzene was continuously fed to the first reactor at a feed rate of 20 L / hr, and polymerization was carried out at a temperature of 150°C in the first reactor, 155°C in the second reactor, and 155-160°C in the third reactor. The resulting polymerization solution was introduced into a two-stage preheater-equipped vacuum devolatilizer tank in series, and after separating unreacted styrene and ethylbenzene, the polymer was extruded into a strand, cooled, and then cut into pellets (P-1). The resin temperature in the first devolatilizer tank was set to 160°C, the pressure in the vacuum devolatilizer tank was 65 kPa, and the resin temperature in the second devolatilizer tank was set to 230°C, and the pressure in the vacuum devolatilizer tank was 0.7 kPa.

[0044] <Resin composition P-2> A raw material solution consisting of 80.1 parts by mass of styrene monomer, 2.8 parts by mass of methacrylic acid monomer, 15.0 parts by mass of ethylbenzene, 2.0 parts by mass of 1-octanol, 0.060 parts by mass of polyoxyethylene lauryl ether (Emulgen 109P manufactured by Kao Corporation), and 0.020 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane (Perhexa C manufactured by NOF Corporation) was continuously fed into the first reactor at a feed rate of 14 L / hr, and polymerization was carried out at a temperature of 125 ° C in the first reactor, 132 ° C in the second reactor, and 132 to 136 ° C in the third reactor. The resulting polymerization solution was introduced into a vacuum devolatilizer tank equipped with a preheater, consisting of two stages in series. After separating unreacted styrene, methacrylic acid, and ethylbenzene, the solution was extruded into a strand shape, cooled, and cut into pellets (P-2). The resin temperature in the first devolatilization tank was set to 160°C, the pressure in the vacuum devolatilization tank was 65 kPa, the resin temperature in the second devolatilization tank was set to 230°C, and the pressure in the vacuum devolatilization tank was 0.7 kPa. The methacrylic acid content of the styrene polymer was 4% by mass.

[0045] <Resin composition P-3> A raw material solution consisting of 75.4 parts by mass of styrene monomer, 6.9 parts by mass of methacrylic acid monomer, 15.0 parts by mass of ethylbenzene, 2.5 parts by mass of 1-octanol, 0.14 parts by mass of polyoxyethylene lauryl ether (Emulgen 109P manufactured by Kao Corporation), and 0.020 parts by mass of 1,1-bis(t-butylperoxy)cyclohexane (Perhexa C manufactured by NOF Corporation) was continuously fed to the first reactor at a feed rate of 14 L / hr, and polymerization was carried out at a temperature of 125 ° C in the first reactor, 132 ° C in the second reactor, and 132 to 136 ° C in the third reactor. The resulting polymerization solution was introduced into a two-stage preheater-equipped vacuum devolatilizer tank in series, and after separating unreacted styrene, methacrylic acid, and ethylbenzene, it was extruded into a strand shape, cooled, and cut into pellets (P-3). The resin temperature in the first devolatilization tank was set to 160°C, the pressure in the vacuum devolatilization tank was 65 kPa, the resin temperature in the second devolatilization tank was set to 230°C, and the pressure in the vacuum devolatilization tank was 0.7 kPa. The methacrylic acid content of the styrene polymer was 10% by mass.

[0046] <<Configuration of reactor used in producing resin compositions P-4 to P-7>> The polymerization process was configured by connecting the following first and second reactors in series. First reactor: 39 L volume complete mixing reactor with agitator Second reactor: 16 L volume plug flow reactor with static mixer

[0047] <Resin composition P-4> A raw material solution consisting of 80.5 parts by mass of styrene monomer, 9.5 parts by mass of methyl methacrylate monomer, 10.0 parts by mass of ethylbenzene, 0.024 parts by mass of t-butylcumyl peroxide (Perbutyl C manufactured by NOF Corporation), and 0.20 parts by mass of t-dodecyl mercaptan was continuously fed to the first reactor at a feed rate of 15 L / hr, and polymerization was carried out at a temperature of 150 ° C in the first reactor and a temperature of 150 ° C in the second reactor. The resulting polymerization liquid was introduced into a vacuum devolatilizer tank equipped with a preheater, which was configured in series with two stages. After separating unreacted styrene, methyl methacrylate, and ethylbenzene, the polymer was extruded into a strand, cooled, and cut into pellets (P-5). The resin temperature in the first devolatilizer tank was set to 160 ° C, the pressure in the vacuum devolatilizer tank was 65 kPa, the resin temperature in the second devolatilizer tank was set to 230 ° C, and the pressure in the vacuum devolatilizer tank was 0.7 kPa. The methyl methacrylate content of the styrene polymer was 10% by mass.

[0048] <Resin composition P-5> A raw material solution consisting of 70.1 parts by mass of styrene monomer, 19.9 parts by mass of methyl methacrylate monomer, 10.0 parts by mass of ethylbenzene, 0.024 parts by mass of t-butylcumyl peroxide (Perbutyl C manufactured by NOF Corporation), and 0.20 parts by mass of t-dodecyl mercaptan was continuously fed to the first reactor at a feed rate of 15 L / hr, and polymerization was carried out at a temperature of 150 ° C in the first reactor and a temperature of 150 ° C in the second reactor. The resulting polymerization liquid was introduced into a vacuum devolatilizer tank equipped with a preheater, which was configured in series with two stages. After separating unreacted styrene, methyl methacrylate, and ethylbenzene, the polymer was extruded into a strand, cooled, and then cut into pellets (P-5). The resin temperature in the first devolatilizer tank was set to 160 ° C, the pressure of the vacuum devolatilizer tank was 65 kPa, the resin temperature in the second devolatilizer tank was set to 230 ° C, and the pressure of the vacuum devolatilizer tank was 0.7 kPa. The methyl methacrylate content of the styrene polymer was 20% by mass.

[0049] <Resin composition P-6> A raw material solution consisting of 41.3 parts by mass of styrene monomer, 48.7 parts by mass of methyl methacrylate monomer, 10.0 parts by mass of ethylbenzene, 0.024 parts by mass of t-butylcumyl peroxide (Perbutyl C manufactured by NOF Corporation), and 0.20 parts by mass of t-dodecyl mercaptan was continuously fed to the first reactor at a feed rate of 15 L / hr, and polymerization was carried out at a temperature of 150 ° C in the first reactor and a temperature of 150 ° C in the second reactor. The resulting polymerization liquid was introduced into a vacuum devolatilizer tank equipped with a preheater, which was configured in series with two stages. After separating unreacted styrene, methyl methacrylate, and ethylbenzene, the polymer was extruded into a strand shape, cooled, and then cut into pellets (P-5). The resin temperature in the first devolatilizer tank was set to 160 ° C, the pressure of the vacuum devolatilizer tank was 65 kPa, the resin temperature in the second devolatilizer tank was set to 230 ° C, and the pressure of the vacuum devolatilizer tank was 0.7 kPa. The methyl methacrylate content of the styrene polymer was 50% by mass.

[0050] <Resin composition P-7> A raw material solution consisting of 16.4 parts by mass of styrene monomer, 63.6 parts by mass of methyl methacrylate monomer, 20.0 parts by mass of ethylbenzene, 0.024 parts by mass of t-butylcumyl peroxide (Perbutyl C manufactured by NOF Corporation), and 0.20 parts by mass of t-dodecyl mercaptan was continuously fed to the first reactor at a feed rate of 15 L / hr, and polymerization was carried out at a temperature of 150 ° C in the first reactor and a temperature of 150 ° C in the second reactor. The resulting polymerization liquid was introduced into a vacuum devolatilizer tank equipped with a preheater, which was configured in series with two stages. After separating unreacted styrene, methyl methacrylate, and ethylbenzene, the polymer was extruded into a strand, cooled, and cut into pellets (P-5). The resin temperature in the first devolatilizer tank was set to 160 ° C, the pressure of the vacuum devolatilizer tank was 65 kPa, the resin temperature in the second devolatilizer tank was set to 230 ° C, and the pressure of the vacuum devolatilizer tank was 0.7 kPa. The methyl methacrylate content of the styrene polymer was 75% by mass.

[0051] <Resin composition P-8> For P-8, "N1, manufactured by Indorama" was used as the PET (polyethylene terephthalate) resin composition.

[0052] <Resin Composition P-9> As the PC (polycarbonate) resin composition, "HL4000 manufactured by Mitsubishi Engineering Plastics Corporation" was used for P-9.

[0053] [Examples 1 to 6 and Comparative Examples 1 to 3] As shown in Table 1, measurements and evaluations were performed for each of Resin Compositions P-1 to P-9 as examples and comparative examples.

[0054]

Table1

[0055] <Dielectric Properties (Relative Permittivity and Dissipation Factor)> The relative permittivity and dissipation factor of the styrene resin composition were measured by the following method. Pellets of each resin composition dried at 80 °C for 2 hours were molded using a hot press machine under the conditions of a temperature of 250 °C and a pressure of 15 MPa to produce a test piece with a thickness of 0.3 mm. After the obtained test piece was allowed to stand for 24 hours under the conditions of a temperature of 25 °C and a humidity of 50%, the relative permittivity and dissipation factor at 24 GHz were measured using a network analyzer (N5227B manufactured by Keysight Technologies), a resonator (SUM-CYLINDER manufactured by SUMTEC), and a high-frequency extender (WR12SAX-M manufactured by Virginia Diodes). Those with a dissipation factor less than 0.0050 were considered to pass.

[0056] <HAZE · Total Light Transmittance> For the test piece with a thickness of 0.3 mm obtained by the above molding method, haze and total light transmittance were measured using a haze meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.) to obtain HAZE (unit: %) and total light transmittance (unit: %). Those with a HAZE less than 0.9% were considered to pass.

[0057] <Water Absorption> The pellets of the resin composition were measured in accordance with JIS K 7209 to measure the water absorption.

[0058] <Vicat Softening Temperature> Pellets of the resin composition were injection-molded using an injection molding machine (IS130FII-3A) manufactured by Toshiba Machine Co., Ltd. at a cylinder temperature of 250°C and a mold temperature of 50°C to obtain test pieces. The Vicat softening point temperature was measured based on JIS K 7206 under the conditions of a 50 N load and a heating rate of 50°C / hr.

[0059] <MFR Retention Rate> Pellets of the resin composition were exposed to an environment of 80°C and 90% RH for 168 hours, and the MFR before and after the exposure was measured. The MFR measurement was carried out at a load of 49 N based on JIS K-7210. For Examples 1 to 6 and Comparative Example 1 (resin compositions P-1 to P-7), the measurement was carried out at 200°C, for Comparative Example 2 (resin composition P-8) at 250°C, and for Comparative Example 3 (resin composition P-9) at 210°C. Taking the MFR before exposure as MFR1 and the MFR after exposure as MFR2, the MFR retention rate was calculated by the following formula. MFR Retention Rate (%) = MFR2 / MFR1 × 100

Claims

1. A styrene-based resin composition for a transparent antenna, comprising: A styrene-based resin composition comprising a styrene-based polymer having 30 to 100 mass % of styrene-based monomer units.

2. 2. The styrene-based resin composition according to claim 1, wherein the styrene-based polymer contains 1 to 50 mass % of a monomer unit A other than a styrene-based monomer unit.

3. The styrene-based resin composition according to claim 2 , wherein the monomer unit A comprises at least one unit selected from the group consisting of a (meth)acrylic acid unit and a (meth)acrylic acid ester unit.

4. 2. The styrene-based resin composition according to claim 1, which has an MFR retention of 90 to 110% after exposure to an environment of 80°C and 90% RH for 168 hours.

5. 2. The styrene-based resin composition according to claim 1, wherein a molded article obtained by molding the styrene-based resin composition has a dielectric loss tangent of less than 0.0050 at a measurement frequency of 24 GHz.

6. A transparent antenna film, comprising a layer formed from the styrene-based resin composition according to any one of claims 1 to 5.

7. A transparent antenna comprising the film according to claim 6.

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