JP2023001634A - Cover for electromagnetic wave radar and module for electromagnetic wave radar - Google Patents

Abstract

To provide a cover for an electromagnetic wave radar with an excellent balance of dielectric properties, heat resistance, and mechanical strength against microwave and millimeter waves.SOLUTION: The cover for an electromagnetic wave radar is obtained from a resin composition including 100 parts by mass of the 4-methyl-1-pentene polymer (A) and 5 to 50 parts by mass of glass filler (B) and by which the following requirements (1) to (2) are satisfied. (1) A dielectric constant measured on the basis of JIS R 1641:2007 and/or JIS R 1660-2:2004 is 3.0 or less. (2) A dissipation factor measured on the basis of JIS R 1641:2007 and/or JIS R 1660-2:2004 is 0.01 or less.SELECTED DRAWING: None

Description

The present invention relates to an electromagnetic wave radar cover and an electromagnetic wave radar module.

An electromagnetic wave radar, for example, detects the presence of objects such as pedestrians and obstacles, the distance to the object, and the relative speed by transmitting electromagnetic waves and receiving the reflected waves that collide with the object and return. It is expected to be applied in a wide range of fields such as automobile collision prevention sensors, automatic driving systems, road information provision systems, security systems, and medical and nursing care devices.

In recent years, especially in automotive applications, social infrastructure applications, and medical and nursing care applications, electromagnetic wave radars have been used with higher frequencies in order to increase the distance to detectable objects and improve the maximum resolution. Therefore, in addition to the use of conventionally used microwaves, the use of electromagnetic waves with a frequency of 30 to 300 GHz, which is in the millimeter wave region, is required.

An electromagnetic wave radar (module) usually has an antenna module that transmits and receives electromagnetic waves and a radome (electromagnetic wave radar cover) that houses or protects the module.
It is known that the electromagnetic wave radar cover reduces transmitted electromagnetic waves due to the dielectric loss of the material, especially high-frequency electromagnetic waves have a large transmission attenuation, and noise is generated in the received and transmitted signals and the strength is reduced. In order to prevent the radar from failing to obtain sufficient performance due to deterioration of the receiving and transmitting accuracy, electromagnetic wave radar covers must have excellent dielectric properties (low dielectric constant, low dielectric loss tangent) is required.

In view of the above, various researches have been conducted on covers for electromagnetic wave radars, and covers described in Patent Documents 1 to 3, for example, are known as covers for millimeter wave radars.

JP 2019-197048 A JP 2020-117651 A JP 2016-121307 A

Covers for millimeter-wave radars are also known, as in Patent Documents 1 to 3, and they have excellent dielectric properties (low dielectric constant, low dielectric loss tangent) against microwaves and millimeter waves, excellent heat resistance, and mechanical strength. An electromagnetic wave radar cover that simultaneously satisfies excellent properties (hardness, tensile properties, bending properties) has not been known.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electromagnetic wave radar cover that is excellent in well-balanced dielectric properties, heat resistance and mechanical strength against microwaves and millimeter waves.

As a result of intensive studies on methods for solving the above problems, the present inventors have found that the above problems can be solved by using a specific composition, and have completed the present invention.
A configuration example of the present invention is as follows.

[1] Obtained from a resin composition containing 100 parts by mass of a 4-methyl-1-pentene polymer (A) and 5 to 50 parts by mass of a glass filler (B) and satisfying the following requirements (1) to (2): electromagnetic wave radar cover.
(1) Permittivity measured according to JIS R 1641:2007 and/or JIS R 1660-2:2004 is 3.0 or less (2) According to JIS R 1641:2007 and/or JIS R 1660-2:2004 Dielectric loss tangent measured in compliance with 0.01 or less

[2] The electromagnetic wave radar cover according to [1], wherein the resin composition satisfies the following requirements (3) to (6).
(3) a specific gravity of 0.8 to 1.2 as measured according to ASTM D792;
(4) Melting point (Tm) of 200 to 260° C. by differential scanning calorimetry (DSC)
(5) Dielectric breakdown voltage measured according to ASTM D149 is 15 kV/mm or more (6) Flexural modulus measured according to ASTM D790 is 2000 MPa or more

[3] The electromagnetic wave radar cover according to [1] or [2], wherein the 4-methyl-1-pentene polymer (A) satisfies the following requirements (Aa) and (Ab).
(Aa) Intrinsic viscosity [η] _A measured in decalin at 135°C is 1.5 to 5.0 dL/g
(Ab) Melting point (Tm _A ) of 200 to 260° C. by differential scanning calorimetry (DSC)

[4] The electromagnetic wave radar cover according to any one of [1] to [3], wherein the glass filler (B) is glass fiber.

[5] The electromagnetic wave radar cover according to any one of [1] to [4], containing 1 to 15 parts by mass of the modified 4-methyl-1-pentene polymer (C).

[6] The electromagnetic wave radar cover according to any one of [1] to [5], wherein the frequency of the electromagnetic waves is millimeter waves of 30 to 300 GHz.

[7] An electromagnetic wave radar module, comprising: an antenna module for transmitting and/or receiving electromagnetic waves; and an electromagnetic wave radar cover according to any one of [1] to [6].

According to the present invention, it is possible to provide an electromagnetic wave radar cover that is excellent in well-balanced dielectric properties, heat resistance, and mechanical strength against microwaves and millimeter waves.

≪Cover for electromagnetic wave radar≫
An electromagnetic wave radar cover (hereinafter also referred to as "this cover") according to the present invention is
A resin composition containing 100 parts by mass of a 4-methyl-1-pentene polymer (A) and 5 to 50 parts by mass of a glass filler (B) and satisfying the following requirements (1) to (2) (hereinafter referred to as "this composition (Also referred to as “things”).

<Present composition>
The present composition contains 100 parts by mass of a 4-methyl-1-pentene polymer (A) and 5 to 50 parts by mass of a glass filler (B), and satisfies the following requirements (1) and (2).
The cover obtained by using this composition satisfying the following requirements (1) and (2) can be said to have excellent permeability to electromagnetic waves (including microwaves and millimeter waves), and is suitably used as a cover for electromagnetic wave radar. be able to.

Requirement (1): The dielectric constant measured in accordance with JIS R 1641:2007 and/or JIS R 1660-2:2004 is 3.0 or less. It is 8 or less, more preferably 2.7 or less, and although the lower limit is not particularly limited, it is, for example, 1.5.
Specifically, the dielectric constant can be measured by the method described in Examples below.

Requirement (2): The dielectric loss tangent measured in accordance with JIS R 1641:2007 and/or JIS R 1660-2:2004 is 0.01 or less. 007 or less, more preferably 0.006 or less, and the lower limit is not particularly limited, but is, for example, 0.000001.
Specifically, the dielectric loss tangent can be measured by the method described in Examples below.

The present composition preferably satisfies the following requirements (3) to (6) in addition to the above requirements (1) to (2).
The present composition that satisfies the above requirements (1) to (2), and further, the present composition that satisfies the following requirements (3) to (6) along with the above requirements (1) to (2) are, for example, a specific amount of the following It can be easily obtained by kneading the polymer (A) and the glass filler (B), particularly by kneading under the following kneading conditions.

Requirement (3): Specific gravity of 0.8 to 1.2 as measured according to ASTM D792
The specific gravity is preferably 0.85-1.15, more preferably 0.9-1.10.
When the specific gravity is within the above range, the mechanical strength is improved and the dielectric constant and dielectric loss tangent can be easily maintained.

Requirement (4): Melting point (Tm) by differential scanning calorimetry (DSC) is 200-260°C
The Tm is preferably 210-250°C, more preferably 220-240°C.
When the Tm is within the above range, a cover having excellent heat resistance can be easily obtained.
Specifically, the Tm can be measured by the method described in Examples below.

Requirement (5): The dielectric breakdown voltage measured in accordance with ASTM D149 is 15 kV/mm or higher. The dielectric breakdown voltage is preferably 20 kV/mm or higher, more preferably 25 kV/mm or higher, and the upper limit is not particularly limited. , for example 40 kV/mm.
When the dielectric breakdown voltage is within the above range, material breakdown due to current is less likely to occur.
Specifically, the dielectric breakdown voltage can be measured by the method described in Examples below.

Requirement (6): Flexural modulus of 2000 MPa or more measured according to ASTM D790 The flexural modulus is preferably 2200 MPa or more, more preferably 2500 MPa or more, and the upper limit is not particularly limited, but is, for example, 7000 MPa.
When the flexural modulus is within the above range, a cover with excellent flexural properties can be easily obtained.
Specifically, the flexural modulus can be measured by the method described in Examples below.

In addition, it is preferable that the present composition has the following flexural strength measured according to ASTM D790.
The bending strength is preferably 40 MPa or more, more preferably 45 MPa or more, and the upper limit is not particularly limited, but is, for example, 100 MPa.

<4-methyl-1-pentene polymer (A)>
The polymer (A) is not particularly limited as long as it is a polymer containing a structural unit derived from 4-methyl-1-pentene, and may be a homopolymer of 4-methyl-1-pentene, 4-methyl It may be a copolymer of -1-pentene and other monomers (eg, α-olefin).
The polymer (A) used in the present composition may be of one type or two or more types.

The content of the structural unit derived from 4-methyl-1-pentene in the polymer (A) is preferably 80 to 100% by mass, more preferably 85 to 100% by mass.
In addition, the content of structural units derived from the other monomers is preferably 0 to 20% by mass, more preferably 0 to 15% by mass. The polymer (A) may contain one or more structural units derived from the other monomer.
By using the polymer (A) in which the content of each structural unit is within the above range, it is possible to easily obtain a cover excellent in moldability, heat resistance, chemical resistance and dielectric properties.
The content of each structural unit is the content when the total of the structural unit derived from 4-methyl-1-pentene and the structural units derived from other monomers is taken as 100% by mass.

As the other monomers, α-olefins having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) are preferred.
The α-olefin may be used singly or in combination of two or more.

Preferred examples of the α-olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene and 1-eicosene.

Among these, ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, and 1-octene are , 1-decene, 1-hexadecene, 1-heptadecene, 1-octadecene are preferred, and ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-hexadecene, 1-heptadecene, 1-octadecene is more preferred.

Examples of monomers other than the α-olefin include vinyl compounds having a cyclic structure such as styrene, vinylcyclopentene, vinylcyclohexane, and vinylnorbornane; vinyl esters such as vinyl acetate; unsaturated organic acids such as maleic anhydride. or derivatives thereof; conjugated dienes such as butadiene, isoprene, pentadiene, and 2,3-dimethylbutadiene; 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1, 5-heptadiene, 7-methyl-1,6-octadiene, dicyclopentadiene, cyclohexadiene, dicyclooctadiene, methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2- Examples include non-conjugated polyenes such as propenyl-2,2-norbornadiene.
These other monomers may be used singly or in combination of two or more.

The intrinsic viscosity [η] _A of the polymer (A) measured in decalin at 135° C. is preferably 1.5 to 5.0 dL/g, more preferably 1.6 to 3.5 dL/g, still more preferably is between 1.7 and 3.2 dL/g.
When the polymer (A) having [η] _A within the above range is used, it is possible to easily obtain a cover having good fluidity, excellent moldability, especially film moldability, and excellent heat resistance.

In this specification, the intrinsic viscosity [η] of the polymer can be measured as follows.
About 20 mg of the polymer is dissolved in 15 mL of decalin, and the specific viscosity η _sp is measured in an oil bath at 135° C. After diluting the decalin solution with 5 mL of decalin solvent, the specific viscosity η _sp is measured in the same manner. . This dilution operation is repeated twice, and the η _sp /C value when the concentration (C) is extrapolated to 0 is defined as the intrinsic viscosity [η] (unit: dL / g) as shown in the following formula (1). do.
[η]=lim(η _sp /C) (C→0) (1)

The melting point (Tm _A ) of the polymer (A) measured by DSC is preferably 200 to 260°C, more preferably 210 to 250°C, still more preferably 220 to 245°C.
By using the polymer (A) having a melting point within the above range, a cover excellent in heat resistance and mechanical properties can be easily obtained.
Tm _A can be controlled by adjusting the stereoregularity of the polymer (A) and the amount of the other monomers.

In this specification, Tm _A can be measured as follows.
Using a DSC measuring device (DSC220C) manufactured by Seiko Instruments Inc., about 5 mg of polymer (A) is packed in an aluminum pan for measurement, heated from room temperature to 280 ° C. at 10 ° C./min, and heated at 280 ° C. for 5 hours. After holding for 1 minute, the temperature is lowered to −50° C. at 10° C./minute, and then the temperature is raised to 280° C. at 10° C./minute. When the polymer (A) has a plurality of peaks, the apex of the peak located on the highest temperature side is taken as the melting point.

The polymer (A) is a conventionally known catalyst for olefin polymerization, such as vanadium-based catalysts, titanium-based catalysts, magnesium-supported titanium catalysts, WO 01/53369, WO 01/27124, WO 01/27124, WO 06/025540, JP-A-03-193796, JP-A-02-41303, etc., using a metallocene catalyst, 4-methyl-1-pentene and, if necessary, other monomers (co) It can be synthesized by polymerization.

A commercial product may be used as the polymer (A), and examples of the commercial product include TPX manufactured by Mitsui Chemicals, Inc.

The content of the polymer (A) in the composition is preferably 50 to 95% by mass, more preferably 55 to 93% by mass, and still more preferably 60 to 90% by mass with respect to 100% by mass of the composition. be.
When the content of the polymer (A) is within the above range, it is possible to easily obtain a cover in which the physical properties of the polymer (A), such as heat resistance, chemical resistance and dielectric properties, are fully exhibited.

<Glass filler (B)>
The glass filler (B) is not particularly limited, and may be fibrous or powdery (particles), but is preferably fibrous, that is, glass fiber.
The glass filler (B) used in the present composition may be of one type or two or more types.

The glass is not particularly limited, and examples thereof include borosilicate glass, E glass, S glass, A glass, AR glass, C glass, D glass, T glass, NE glass, H glass, quartz, low dielectric constant glass, high A dielectric glass is mentioned. Among these, E glass is preferable because a glass filler having a refractive index within the above range can be easily obtained.

The glass fibers may be long fibers, short fibers, or chopped fibers, and the cross-sectional shape perpendicular to the longitudinal direction of the glass fibers is not particularly limited, but is preferably circular.
Examples of the glass fiber include surface treatment agents such as silane-based coupling agents, titanate-based coupling agents, boron-based coupling agents, aluminate-based coupling agents, and zirco-aluminate-based coupling agents. A fiber whose surface has been treated with a known sizing agent or the like may also be used.

The average fiber diameter of the glass fibers is preferably more than 6.5 μm and 20 μm or less, more preferably 8 to 19 μm, still more preferably 10 to 18 μm.
When the average fiber diameter is within the above range, the fibers are less likely to break when forming a cover from the present composition, and a cover excellent in impact strength, appearance, rigidity, heat resistance, etc. can be easily formed.

The average fiber length of the glass fibers is preferably 0.1 to 15 mm, more preferably 0.3 to 13 mm, still more preferably 0.5 to 13 mm.
When the average fiber length is within the above range, the effect of reinforcing mechanical properties by the glass fibers is likely to be exhibited, and a cover in which the glass fibers are uniformly dispersed can be easily obtained, which is preferable.
The average fiber diameter and average fiber length are values calculated by visually measuring the length of 100 glass fibers with an optical microscope.

The content of the glass filler (B) in the present composition is 5 to 50 parts by mass, preferably 10 to 49 parts by mass, more preferably 100 parts by mass of the polymer (A) in the present composition. 15 to 48 parts by mass.
When the content of the glass filler (B) is within the above range, the effect of reinforcing the mechanical properties of the glass filler (B) is sufficiently exhibited, and a cover having excellent dielectric properties, impact strength, appearance, rigidity, heat resistance, etc. can be easily obtained. can be formed into

<Other ingredients>
The present composition may contain components other than the polymer (A) and the glass filler (B), depending on its use, as long as the effects of the present invention are not impaired.
Examples of other components include modified 4-methyl-1-pentene polymer (C), polyolefin resins other than polymers (A) and (C), compatibilizers, nucleating agents, antiblocking agents, and pigments. , Dyes, fillers, lubricants, plasticizers, release agents, antioxidants, flame retardants, UV absorbers, antibacterial agents, surfactants, antistatic agents, weather stabilizers, heat stabilizers, anti-slip agents, foaming agents, crystallization aids, antifogging agents, anti-aging agents, hydrochloric acid absorbers, impact modifiers, cross-linking agents, co-cross-linking agents, cross-linking aids, adhesives, softeners, processing aids and dispersants. Conventionally known components can be used as these other components.
Each of the other components may be used singly or in combination of two or more.

The content of the other components (the total amount of other components to be contained) is not particularly limited as long as it does not impair the object of the present invention, but is preferably 0.001 to 30% by mass with respect to 100% by mass of the composition. is.

[Modified 4-methyl-1-pentene polymer (C)]
Examples of the polymer (C) include a polymer obtained by modifying a 4-methyl-1-pentene polymer with an unsaturated carboxylic acid or a derivative thereof.
By using the polymer (C), the compatibility between the polymer (A) and the glass filler (B) increases, and it tends to be possible to easily obtain a cover having more excellent mechanical strength.

Examples of the 4-methyl-1-pentene polymer before modification with an unsaturated carboxylic acid or derivative thereof (hereinafter also referred to as "unmodified polymer") include polymers similar to the polymer (A). mentioned.

Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, fumaric acid, undecylenic acid, tetrahydrophthalic acid, nadic acid (endo-cis-bicyclo[ 2.2.1]hept-5-ene-2,3-dicarboxylic acid).
Examples of the unsaturated carboxylic acid derivative include anhydrides of unsaturated carboxylic acids such as maleic anhydride, citraconic anhydride and nadic anhydride; and half esters of polybasic acids such as maleic acid and fumaric acid.
Among these, maleic anhydride is particularly preferred.

The content (modified amount) of the structural unit derived from the unsaturated carboxylic acid or derivative thereof contained in the polymer (C) is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass. .
The degree of modification can be adjusted by the amount of unsaturated carboxylic acid or derivative thereof used, reaction temperature, reaction time, type and amount of radical initiator used, and the like.
The amount of modification can be measured using infrared spectroscopy (IR) or NMR.

Methods for synthesizing the polymer (C) include, for example, a method of reacting an unmodified polymer and an unsaturated carboxylic acid or a derivative thereof under heating and melting, a method of dissolving both in an appropriate solvent and then reacting them, and a method of reacting them in powder form. and a method of reacting both in a solid state. Through these reactions, the polymer (C) is obtained by graft-polymerizing the unsaturated carboxylic acid or its derivative to the unmodified polymer.

When the present composition contains the polymer (C), the content of the polymer (C) in the present composition is preferably 1 to 15 mass parts per 100 parts by mass of the polymer (A) in the present composition. parts, more preferably 2 to 10 parts by mass, preferably 3 to 7 parts by mass.
When the content of the polymer (C) is within the above range, the compatibility between the polymer (A) and the glass filler (B) is enhanced, and a cover with more excellent mechanical strength can be easily obtained.

<Method for producing the present composition>
The method for producing the present composition is not particularly limited, but for example, a method of mixing the polymer (A), the glass filler (B), and the other components and then melt-kneading them can be mentioned.

The melt-kneading method is not particularly limited, and can be carried out using a melt-kneading device such as an extruder that is generally commercially available.
For example, the cylinder temperature of the part where the mixture is kneaded by the kneader is usually 200-320°C, preferably 220-300°C. If the temperature is lower than the above range, kneading may be insufficient due to insufficient melting, and it may be difficult to improve the physical properties of the resulting composition. On the other hand, if the temperature is higher than 320°C, thermal decomposition of components such as polymer (A) and polymer (C) may occur.

≪Book cover≫
The present cover is not particularly limited as long as it is a cover obtained using the present composition, but is preferably a cover formed from the present composition and obtained by molding the present composition. One aspect of the present cover consists of (only) the present composition. Thus, in one aspect of the invention, the composition and the cover are the same.
The present cover may be obtained by laminating a film or sheet obtained from the present composition with another film or sheet to form a composite laminate.
Further, the present cover may be a cover obtained from the present composition as a whole, and for example, only a portion corresponding to a path related to transmission or reception of electromagnetic waves may be a cover obtained from the present composition. can do.

The thickness of the cover may be appropriately selected in consideration of the desired shape, required dielectric properties, mechanical strength, etc., but is preferably 1 to 10 mm, more preferably 1.2 to 8 mm, further preferably 1.5 to 1.5 mm. 7 mm.

The shape of this cover is not particularly limited, and may be any shape corresponding to the shape of an antenna module, millimeter wave radar, or the like, and may have a curved surface portion, a corner portion, or the like.

Examples of the method for forming the present cover include various known molding methods using the present composition, and examples thereof include various molding methods such as injection molding, extrusion molding, and press molding.
The molding conditions include the same molding conditions as those for conventionally known 4-methyl-1-pentene polymers.

This cover is preferably a so-called millimeter-wave radar cover, in which the electromagnetic wave has a frequency of 30 to 300 GHz.
Since the present cover has excellent dielectric properties even for such millimeter waves, it can be particularly suitably used for millimeter wave radar.
Such a millimeter-wave radar cover is preferable because the radar module can be miniaturized.

This cover can be widely used for various in-vehicle sensors, electromagnetic wave radars for railways, aircraft, and ships, and electromagnetic wave radars in the fields of transportation, medical care, nursing care, security, and information content transmission.
Specifically, automatic brake control device, inter-vehicle distance control device, pedestrian accident reduction steering device, erroneous transmission suppression control device, acceleration suppression device for pedal misapplication, approaching vehicle warning device, lane keeping support device, collision prevention device In-vehicle electromagnetic wave radar used for warning devices, parking assistance devices, alerting devices for obstacles around vehicles, etc. Platform monitoring/railway crossing obstacle detection devices, content transmission devices in trains, streetcar/railroad collision prevention devices, foreign objects in runways Electromagnetic wave radar for railroads, aviation, and ships used for detecting other ships and islands; Electromagnetic wave radar for traffic infrastructure such as intersection monitoring device and elevator monitoring device; Electromagnetic wave radar for various security devices; It can be suitably used for medical and nursing care electromagnetic wave radars such as systems; electromagnetic wave radars for transmitting various information contents;

≪Module for electromagnetic wave radar≫
It has an antenna module for transmitting and/or receiving electromagnetic waves and a main cover.
The book cover is preferably used to store or protect the antenna module.
Further, the electromagnetic wave radar module may have a housing, a connector, a radar board, a circuit board, a casing, and the like.

The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

<raw materials>
The following raw materials were used in the following examples.
· 4-methyl-1-pentene polymer (A)
DX810PW (manufactured by Mitsui Chemicals, Inc., [η]: 3.0 dL/g, melting point: 230°C)
・Glass filler (B)
ECS 03 T-747H (manufactured by Nippon Electric Glass Co., Ltd., E glass)
- Modified 4-methyl-1-pentene polymer (C)
Maleic acid-modified 4-methyl-1-pentene polymer obtained in Production Example 1 below

[Production Example 1]
4-Methyl-1-pentene polymer (DX810PW) 100 parts by weight, maleic anhydride (MAH) 3 parts by weight, 2,5-dimethyl-2,5-di(t-butylperoxy) as a radical initiator ) 0.05 part by mass of hexane (Perhexa 25B (manufactured by NOF Corporation)) was added and mixed, then supplied to an extruder set at 300° C., melt-mixed and pelletized.
The pellets thus obtained were heated and dissolved in paraxylene at 130° C. and allowed to cool. Acetone was added to the resulting solution to precipitate a polymer, which was filtered and dried to obtain a modified 4-methyl-1-pentene polymer.
As a result of measuring the obtained modified 4-methyl-1-pentene polymer by infrared absorption spectrum, it was found that 3.9% by mass of MAH was graft-polymerized in the polymer. The intrinsic viscosity [η] of the obtained modified 4-methyl-1-pentene polymer was 0.76 dL/g.

[Examples 1 to 4]
Using a twin-screw extruder (PCM43, manufactured by Ikegai Co., Ltd., screw diameter: 43 mm, temperature: 280° C., rotation speed: 200 rpm), 4-methyl-1-pentene polymer (A) and glass filler (B) were prepared. , and the modified 4-methyl-1-pentene polymer (C) were melt-kneaded at the blending ratio shown in Table 1 to obtain each resin composition.

Using a 70-ton injection molding machine (M70B) manufactured by Meiki Seisakusho Co., Ltd., the resulting resin composition was molded into thicknesses of 0.5 mm and 2 mm under conditions of a cylinder temperature of 280°C and a mold temperature of 60°C. Alternatively, an injection test piece was created by injecting into a square plate of 3.2 mm.

<Specific gravity>
The specific gravity of the obtained resin composition was measured by the density gradient tube method according to ASTM D792.

<Melting point (Tm)>
Using a DSC measuring device (DSC220C) manufactured by Seiko Instruments Inc., exothermic and endothermic curves were obtained, and the temperature at the maximum melting peak position during heating was defined as the melting point (Tm). Measurement was performed as follows.
About 5 mg of a sample was cut out from an injection test piece with a thickness of 0.5 mm, packed in an aluminum pan for measurement, heated from 20° C. to 280° C. at a heating rate of 10° C./min, held at 280° C. for 5 minutes, and then heated to 10° C. After the temperature was lowered to 20°C at a cooling rate of °C/min and held at 20°C for 5 minutes, the temperature was again raised from 20°C to 280°C at a heating rate of 10°C/min, and again at a cooling rate of 50°C/min. The temperature was lowered to 50°C. The melting peak that appeared during the second heating was taken as the melting point (Tm).

<Insulation breakdown voltage>
A 2 mm-thick injection test piece was cut into a square shape of 100 mm wide and 100 mm long, and the dielectric breakdown voltage (kV/mm) was measured by the short-time breakdown method (23° C.) according to ASTM D149.

<Permittivity and dissipation factor>
A 2 mm thick injection test piece was cut into a square shape of 100 mm wide and 100 mm long, and the dielectric constant and dielectric loss tangent at the following frequencies were measured at 23°C.
· 1 MHz: Measured under room temperature conditions by the cavity resonator perturbation method in accordance with IEC62810.
· 19 GHz: Measured under room temperature conditions by the cylindrical cavity resonance method in accordance with JIS R1641:2007.
· 53 GHz: Measured under room temperature conditions using a Fabry-Perot resonator in accordance with JIS R 1660-2:2004.
· 106 GHz: Measured under room temperature conditions using a Fabry-Perot resonator in accordance with JIS R 1660-2:2004.

<Tensile test>
A 2 mm thick injection test piece was used to prepare an ASTM-4 dumbbell-shaped test piece in accordance with ASTM D638, and a universal tensile tester 3380 manufactured by Instron Co., Ltd. Tensile speed: 50 mm / min, measurement temperature : A tensile test was performed at 23°C to measure tensile strength (MPa) and tensile elongation at break (%).

<Bending properties>
An ASTM-4 dumbbell-shaped test piece was prepared according to ASTM D790 using a 3.2 mm thick injection test piece, tensile speed: 1.3 mm / min, span: 51 mm, measurement temperature: 23 ° C. A bending test was performed under the conditions to measure bending strength (MPa) and bending elastic modulus (MPa).

<Rockwell hardness>
A test piece was prepared according to ASTM D785 from an injection test piece having a thickness of 2 mm, and tested on an R scale with an indenter diameter of 12.7 mm and a test load of 588.4 N to measure Rockwell hardness.

Claims (7)

An electromagnetic wave obtained from a resin composition containing 100 parts by mass of a 4-methyl-1-pentene polymer (A) and 5 to 50 parts by mass of a glass filler (B) and satisfying the following requirements (1) to (2) Radar cover.
(1) Permittivity measured according to JIS R 1641:2007 and/or JIS R 1660-2:2004 is 3.0 or less (2) According to JIS R 1641:2007 and/or JIS R 1660-2:2004 Dielectric loss tangent measured in compliance with 0.01 or less The electromagnetic wave radar cover according to claim 1, wherein the resin composition satisfies the following requirements (3) to (6).
(3) a specific gravity of 0.8 to 1.2 as measured according to ASTM D792;
(4) Melting point (Tm) of 200 to 260° C. by differential scanning calorimetry (DSC)
(5) Dielectric breakdown voltage measured according to ASTM D149 is 15 kV/mm or more (6) Flexural modulus measured according to ASTM D790 is 2000 MPa or more 3. The electromagnetic wave radar cover according to claim 1, wherein said 4-methyl-1-pentene polymer (A) satisfies the following requirements (Aa) and (Ab).
(Aa) Intrinsic viscosity [η] _A measured in decalin at 135°C is 1.5 to 5.0 dL/g
(Ab) Melting point (Tm _A ) of 200 to 260° C. by differential scanning calorimetry (DSC) The electromagnetic wave radar cover according to any one of claims 1 to 3, wherein the glass filler (B) is glass fiber. The electromagnetic wave radar cover according to any one of claims 1 to 4, comprising 1 to 15 parts by mass of the modified 4-methyl-1-pentene polymer (C). The electromagnetic wave radar cover according to any one of claims 1 to 5, wherein the frequency of said electromagnetic waves is millimeter waves of 30 to 300 GHz. An electromagnetic wave radar module, comprising: an antenna module for transmitting and/or receiving electromagnetic waves; and the electromagnetic wave radar cover according to any one of claims 1 to 6.