JPH0562482B2 - - Google Patents

Description

[Detailed description of the invention]

[] Object of the Invention The present invention relates to a reflector for a circularly polarized antenna made of a laminate having a metal layer serving as a radio wave reflecting layer as an intermediate layer. More specifically, (A) a metal layer having a thermosetting coating layer with excellent weather resistance and (B) an olefinic polymer layer containing an inorganic filler are laminated in sequence,
The thickness of the coating layer is 5 microns to 5 mm,
The thickness of the metal layer is 5 microns to 1 mm, and the thickness of the inorganic filler-containing olefinic polymer layer is
500 microns to 15 mm, the content of this inorganic filler is 10 to 80% by weight, and this inorganic filler-containing olefin polymer layer is composed of a skin layer and a core layer, and the skin layer is essentially free. The core layer is a foam layer, and the average expansion ratio of the olefinic polymer layer containing an inorganic filler is 1.005.
The present invention relates to a reflector for a circularly polarized antenna, characterized in that the resistance is 1.50 to 1.50, and the object thereof is to provide a reflector for a circularly polarized antenna with good weather resistance. [] Background of the Invention Satellite broadcasting such as high-definition television broadcasting, still image broadcasting, text multiplex broadcasting, PCM (pulse code modulation) audio broadcasting, and facsimile broadcasting using geostationary satellites will be used in countries around the world such as Europe, America, and Japan in the near future. Its practical application is planned. However, since a geostationary satellite has only one orbit, there is a risk of interference between multiple broadcast radio waves. In order to avoid such mutual interference of broadcast waves, it is necessary to utilize cross-polarization identification of satellite broadcast receiving antennas. In this way, when receiving terrestrial broadcast waves, the radio waves are linearly polarized horizontally or vertically, and the polarization plane of the receiving antenna is matched to the polarization plane of the broadcast waves, using cross-polarization discrimination. However, when receiving radio waves from a broadcasting satellite, the polarization plane shifts due to disturbances caused by the ionosphere in the radio wave propagation path and the angle of incidence of the radio waves at the receiving point, so the above-mentioned method is not possible. It is difficult to match such planes of polarization. Frequency allocation to multiple broadcasting satellites is likely to be done taking into account the degree of polarization plane discrimination from the point of view of effective use of satellite broadcasting frequency bands.
For satellite broadcast radio waves with such frequency allocation, the quality of the polarization plane adjustment of the receiving antenna directly determines the level of interference between broadcast channels, so if the broadcast satellite radio waves are linearly polarized, there will be large cross-polarization. One cannot expect to obtain any degree of discrimination. However, when broadcasting satellite radio waves are circularly polarized waves, it is easy for ordinary listeners to identify them by the direction in which the circularly polarized waves are applied, regardless of the deviation of the plane of polarization as described above. The receiving antenna not only adjusts its pointing direction to point to the desired broadcasting satellite, but also does not require adjustment of the plane of polarization, making it much easier to adjust the receiving antenna than when linearly polarized waves are used. Therefore, it is possible to obtain the degree of polarization discrimination as designed for the receiving antenna. For these reasons, plans are being made to use circularly polarized waves for broadcasting satellite radio waves in future satellite broadcasting systems. On the other hand, conventional circularly polarized antennas include those using a conical hoe, two dipoles set at right angles, and parabolic antennas that use these antennas as the primary radiator. However, because the structure is complex and large, and manufacturing costs are high, it is not suitable for general audience receiving antennas for receiving satellite broadcast radio waves using microwaves in the 12 gigahertz (GHz) band. do not have. On the other hand, the structure is extremely simple, and as a small and lightweight microwave antenna, a rectangular waveguide is extended in the axial direction from the center of a parabolic reflector, and its tip is curved so that the opening end surface becomes a parabolic shape. so that it faces the parabolic reflector at the focal point,
There is a so-called Hihat-type parabolic antenna that uses this as a primary radiator. This antenna is widely used in microwave antennas for mobile relays, etc., but all conventional Hihatt-type parabolic antennas now transmit and receive linearly polarized waves using short waveguides as described above. Therefore, it cannot be used for circularly polarized waves. Generally, metal plates or metal nets have been used as parabolic antennas. However, since metals corrode, it is necessary to use anticorrosive alloys or apply anticorrosive coatings. If anti-corrosion alloys are used, they are expensive. On the other hand, regarding anti-corrosion coating,
In order to achieve complete corrosion protection, it is necessary to repeat the coating several times, which not only increases the cost, but also causes the problem that the coated product deteriorates after being used for many years. Furthermore, attempts have been made to manufacture radio wave reflecting plates in which glass fibers with metallized surfaces are laminated to thermosetting resins such as unsaturated polyester resins as a radio wave reflecting layer, but the manufacturing method is complicated and It has been extremely difficult to maintain the radio wave reflecting layer at a constant thickness and without unevenness. Recently, the present inventors have proposed manufacturing a reflector for a circularly polarized antenna by insert injection molding or the like by inserting a thermoplastic resin into a metal layer (metal foil) that functions to reflect radio waves. Although the radio wave reflection performance of the circularly polarized antenna reflector manufactured in this way was good, it was necessary to develop the strength of the reflector as a structure and to attach it to the support rod. It was necessary to install ribs with a width of 2 to 10 mm and a height of 2 to 10 mm. If such ribs and thick parts are attached to the back side of the metal layer on the front side of the reflector, so-called sink marks will occur on the ribs and thick part on the back side of the metal layer on the front side of the reflector, resulting in poor appearance and reduced radio wave reflection performance. There was a problem. [] Structure of the Invention Based on the above, the present inventors discovered that even though the manufacturing process is simple, the radio wave reflection ability is excellent, and the back side has ribs and thick parts, sink marks do not occur on the front side. As a result of various searches to obtain a reflector for a circularly polarized antenna that can maintain its performance for a long period of time without causing any damage, we found that at least (A) a metal layer having a thermosetting coating layer with good weather resistance; (B) A laminate formed by sequentially laminating inorganic filler-containing olefin polymer layers, and the thickness of the coating layer is 5.
The thickness of the metal layer is 5 microns to 1 mm, and the thickness of the inorganic filler-containing olefinic polymer layer is 500 microns to 5 mm.
15mm, and the content of inorganic filler in this layer is 10~
This inorganic filler-containing olefinic polymer layer is composed of a skin layer and a core layer, where the skin layer is essentially a non-foamed layer, the core layer is a foamed layer, and the inorganic filler-containing olefinic polymer layer is 80% by weight. A reflector for a circularly polarized antenna, characterized by an average expansion ratio of 1.005 to 1.50 for the olefinic polymer layer contained therein, not only has good durability but also has excellent radio wave reflection properties and an improved appearance. We have found that there is no problem and have arrived at the present invention. [] Effects of the Invention The reflector for a circularly polarized antenna of the present invention exhibits the following effects (features) including its manufacturing process. (1) Due to its excellent corrosion resistance, there is no change in radio wave reflection characteristics over a long period of time. (2) Since the coefficient of linear expansion of the metal layer and the inorganic filler-containing olefinic polymer layer is extremely small, no separation occurs between the layers even if subjected to heat cycles (repetitive cold and hot temperatures) for a long period of time. (3) The reflector for a circularly polarized antenna is lightweight and the manufacturing process is simple. (4) The metal layer can be formed uniformly, and there is no uneven reflection of radio waves. (5) Olefinic polymers containing inorganic fillers can be easily formed into various complex shapes, and therefore have good appearance and functionality. (6) The mechanical strength (especially rigidity) of the circularly polarized antenna reflector is excellent. (7) It is lightweight. (8) Even if there are ribs and thick parts on the back surface of the circularly polarized antenna reflector, there will be no sink marks on the appearance and the radio wave reflection characteristics will not deteriorate. [] Detailed Description of the Invention (A) Paint The paint used to manufacture the metal layer having a thermosetting coating layer with good weather resistance of the present invention is widely produced industrially, and is widely used for metals. It is used as a paint in many ways.
The manufacturing method and various physical properties of these paints are well known. These paints are classified into solvent type using organic solvents such as toluene and xylene, aqueous emulsion type, and solvent-free type, but any type of paint can be selected depending on the coating method.
Typical examples of these paints include unsaturated polyester resin paints, polyurethane resin paints obtained by reacting polyester polyols, polyether polyols, or polyurethane polyols with diisocyanates, aminoalkyd resin paints, and thermal paints. Examples include curable acrylic resin paints, melamine resin paints, cyanoacrylate resin paints, epoxy resin paints, silicone resin paints, organic titanate paints, and acrylic urethane resin paints. Furthermore, additives such as matting agents such as silicic acid, coloring agents such as pigments and dyes, antioxidants, and ultraviolet absorbers can be added to these paints. Among the above paints,
Polyurethane resin paints, thermosetting acrylic resin paints, epoxy resin paints, and aminoalkyd resin paints are preferred because of their excellent weather resistance. Particularly, by incorporating an antioxidant and an ultraviolet absorber into the paint of the present invention, a paint with good weather resistance can be obtained, which is suitable. (B) Metal Further, typical examples of metals that are raw materials for the metal layer in the present invention include simple metals such as aluminum, iron, nickel, copper, and zinc, and alloys containing these metals as main components (for example, stainless steel , brass). These metals do not need to be surface-treated, and may be previously subjected to surface treatment such as chemical treatment or plating treatment. Furthermore, those that have been painted or printed can also be preferably used. (C) Olefin polymer In addition, the olefin polymer used to produce the inorganic filler-containing olefin polymer layer in the present invention includes an ethylene homopolymer, a propylene homopolymer, and an ethylene and propylene homopolymer. Copolymers of ethylene and/or propylene with other α having at most 12 carbon atoms
-Copolymers with olefins (copolymerization ratio of α-olefins is at most 20% by weight). Melt index of these olefin polymers (according to JIS K-6760, temperature
Measured at 190℃ and a load of 2.16Kg, hereinafter referred to as "MI") or melt flow index (according to JIS K-6758, measured at a temperature of 230℃)
and a load of 2.16 kg (hereinafter referred to as "MFI") is preferably 0.01 to 100 g/10 minutes, particularly preferably 0.02 to 80 g/10 minutes. If an olefinic polymer having an MI or MFI of less than 0.01 g/10 min is used, the resulting mixture will not have good moldability. On the other hand, 100g/
When using an olefin polymer that lasts for more than 10 minutes,
The mechanical properties of the resulting molded product are poor. moreover,
Low density (0.900g/cm ³ ) or high density (0.980
g/cm ³ ) of an ethylene homopolymer or a copolymer of ethylene and a small amount of the above α-olefin, or a propylene homopolymer or a random or block copolymer of propylene and ethylene and/or other α-olefins. is desirable. These olefinic polymers are produced by using a catalyst system (so-called Ziegler catalyst) obtained from a transition metal compound and an organoaluminum compound, and a chromium-containing compound (e.g., chromium oxide) supported on a carrier (e.g., silica). It can also be obtained by homopolymerizing or copolymerizing olefins using a catalyst system (so-called Phillips catalyst) or a radical initiator (eg, an organic peroxide). Furthermore, in the present invention, modified materials obtained by graft polymerizing these olefinic polymers with a compound having at least one double bond (for example, an unsaturated carboxylic acid, a monobasic carboxylic acid, a vinyl silane compound), Also included are polyolefins. These olefin polymers and modified polyolefins may be used alone or in combination of two or more. Furthermore, two or more of these olefin polymers and modified polyolefins may be used as a resin blend in any proportion. The production methods for these olefin polymers and modified polyolefins are well known. (D) Inorganic filler The inorganic filler used to produce the inorganic filler-containing olefinic polymer layer is generally one widely used in the fields of synthetic resins and rubber. These inorganic fillers are preferably inorganic compounds that do not react with oxygen and water and do not decompose during kneading and molding. The inorganic fillers include metals such as aluminum, copper, iron, lead and nickel, oxides of these metals and metals such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony and titanium, and their water. It is broadly classified into compounds such as hydrates (hydroxides), sulfates, carbonates, silicates, their double salts, and mixtures thereof. Typical examples of the inorganic fillers include the above-mentioned metals, aluminum oxide (alumina), its hydrates, calcium hydroxide, magnesium oxide (magnesia), magnesium hydroxide, zinc oxide (zinc white), red lead, and lead. Lead oxides such as mortar, magnesium carbonate, calcium carbonate,
Basic magnesium carbonate, white carbon,
Asbestos, mica, talc, glass fiber, glass powder, glass beads, clay, diatomite, silica, wollastonite, iron oxide, antimony oxide, titanium oxide (titania), lithopone, pumice powder, aluminum sulfate (gypsum, etc.) , zirconium silicate, zirconium oxide, barium carbonate,
Examples include dolomite, molybdenum disulfide and iron sand. Among these inorganic fillers, those in powder form preferably have a diameter of 1 mm or less (preferably 0.5 mm or less). In addition, the fibrous material has a diameter of 1 to 500 microns (preferably 1 to 300 microns) and a length of 0.1 to 6 mm (preferably
0.1 to 5 mm) is desirable. Furthermore, the diameter of the flat plate is 2 mm or less (preferably 1 mm or less)
Preferably. (E) Structure of each layer (1) Coating layer The coating layer of the present invention functions to prevent corrosion of the metal layer. From this, the thickness is 5 microns to 1 mm, and 10
Preferably it is from micron to 0.5 mm, particularly preferably from 10 micron to 0.3 mm. If the thickness of this coating layer is less than 5 microns, not only will the metal layer corrode, but it will also wear out and be exposed due to contact and friction with other parts during use. I have a problem. On the other hand, if it exceeds 5 mm, it is not preferable because it not only lowers the reflectance of radio waves but also increases the cost and weight of the laminate. (2) Metal layer Furthermore, the metal layer of the present invention functions to reflect radio waves. The thickness of this metal layer is 5
The diameter is from micron to 1 mm, preferably from 5 to 500 micron, particularly preferably from 10 to 500 micron. If the thickness of the metal layer is less than 5 microns, the metal layer is likely to wrinkle or fold during the production of a laminate, resulting in problems in terms of appearance and performance. On the other hand, 1mm
If it exceeds this, not only will the weight increase, but also the cost will increase, and furthermore, it will cause problems when bending or bending the laminate. (3) Inorganic filler-containing olefin polymer layer The composition ratio of the inorganic filler in the inorganic filler-containing olefin polymer layer of the present invention is 10 to 10.
80% by weight (that is, the composition ratio of the olefin polymer is 90 to 20% by weight), preferably 10 to 70% by weight, and particularly preferably 10 to 60% by weight. The composition ratio of the inorganic filler in the inorganic filler-containing olefin polymer layer is 10% by weight.
If the temperature is less than 100%, the linear expansion coefficient of the inorganic filler-containing olefin polymer layer is too different from that of the metal layer, and peeling occurs between the metal layer and the inorganic filler-containing olefin polymer layer during the beat cycle. In addition, there is a problem that the rigidity of the obtained laminate is insufficient. On the other hand, if it exceeds 80% by weight, it is difficult to produce a uniform composition, and even if a uniform composition is obtained, it will be difficult to produce a laminate by sheet production or injection molding as described below. In this case, it is not possible to obtain a good product (laminate). The thickness of this inorganic filler-containing olefinic polymer layer is 500 microns to 15 mm;
-10 mm is desirable, and 1-7 mm is especially suitable. If the thickness of the inorganic filler-containing olefinic polymer layer is less than 500 microns, it is undesirable because it lacks rigidity and may be deformed or damaged by external force. On the other hand, if it exceeds 15 mm, it will take time to cool during molding and the weight will increase, causing problems in use. The thickness of the skin layer in the inorganic filler-containing olefin polymer layer is usually 5 to 45% of the total thickness of the inorganic filler-containing olefin polymer layer.
%. The thickness of the skin layer in this inorganic filler-containing olefin polymer layer is 5% of the total thickness of the inorganic filler-containing olefin polymer layer.
If it is less than that, foaming marks will remain on the surface and the appearance will be poor. On the other hand, if it exceeds 45%, sink marks will occur on the ribs and thick parts of the back side. The blowing agent added to the inorganic filler-containing olefin polymer layer constituting this core layer is not particularly limited as long as it is a blowing agent that is generally used in the olefin polymer industry. Alternatively, organic physical and chemical blowing agents can be used. The physical blowing agent is at least a gas at the molding temperature described below, and does not have any adverse effects on the olefinic polymer or the inorganic filler blended (added). Representative examples include hydrocarbons such as pentane, butane and propane, organic compounds such as halogenated hydrocarbons and alcohols, and inorganic elements and compounds such as nitrogen gas and carbon dioxide gas. In addition, although chemical blowing agents do not decompose near room temperature, they generate carbon dioxide gas, nitrogen gas, ammonia, etc. at the molding temperature described below.
It does not have any adverse effects on the inorganic filler that is blended (added). Typical examples include inorganic blowing agents such as sodium bicarbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite and azide compounds, as well as azo compounds (e.g. azodicarbonamide, barium azodicarboxylate) and sulfonyl hydrazide systems. Examples include compounds. These blowing agents may be used alone;
Two or more types may be used in combination. Furthermore, a foaming aid may be added. The amount of this blowing agent varies depending on the thickness of the inorganic filler-containing olefinic polymer layer, the thickness of the ribs and thick parts on the back of the reflector, and their height, but in general, inorganic filler A suitable amount is 0.1 to 20% by weight of the agent-containing olefinic polymer layer. The average expansion ratio of the inorganic filler-containing olefinic polymer layer is 1.005 to 1.50, and 1.005 to 1.50.
A value of 1.45 is desirable, and a value of 1.01 to 1.40 is particularly preferred. If the average expansion ratio of the inorganic filler-containing olefinic polymer layer is less than 1.005, sink marks will occur on the surface of the resulting molded product. On the other hand, if it exceeds 1.50, foaming marks will remain on the skin layer of the inorganic filler-containing olefinic polymer layer, resulting in poor appearance. In producing this inorganic filler-containing olefin polymer layer, we use stabilizers against oxygen, heat and ultraviolet rays, metal deterioration inhibitors, heat retardants, colorants, electricity property improver,
Additives such as antistatic agents, lubricants, processability improvers, and tackiness improvers may be added to the extent that they do not impair the properties of the inorganic filler-containing olefinic polymer layer composition of the present invention. When producing the inorganic filler-containing olefin polymer of the present invention (including when the above additives are blended), dry blending is performed using a mixer such as a Henschel mixer that is commonly used in each industry. It can be obtained by melt-kneading using a mixer such as a Banbury mixer, kneader, roll mill, or screw extruder. At this time, a uniform composition can be obtained by dry blending in advance and melt-kneading the resulting composition (mixture). In particular, it is preferable to use the olefinic polymer in the form of powder because it allows for more uniform mixing. In this case, the mixture is generally melt-kneaded and then formed into pellets, which are then subjected to the molding described later. In producing the inorganic filler-containing olefin polymer of the present invention, all the ingredients may be mixed at the same time, or some of the ingredients may be mixed in advance to produce a so-called masterbatch, and the resulting masterbatch and the remaining may be mixed with other ingredients. When melt-kneading is performed to produce the above-mentioned compound, it must be carried out at a temperature higher than the melting point or softening point of the olefinic polymer used, but if carried out at a high temperature, the olefinic polymer will deteriorate. For these reasons, the temperature is generally 20°C higher than the melting point or softening point of the olefin polymer (preferably higher than 50°C), but it is carried out within a temperature range that does not cause deterioration. Furthermore, it is necessary to melt and knead the foaming agent in a state in which the foaming agent is not foamed. (F) Reflector for Circularly Polarized Antenna The reflector for circularly polarized antenna of the present invention will be explained below with reference to FIGS. 1 to 3. FIG. 1 is a partial perspective view of an antenna to which a reflector for a circularly polarized antenna is attached. FIG. 2 is a sectional view of the reflector for the circularly polarized antenna. Moreover, FIG. 3 is a partially enlarged view of the cross-sectional view. In FIG. 1, A is a reflector for a circularly polarized antenna of the present invention, B is a converter, C is a converter support rod, and D is a reflector support rod. Further, E is a wiring. Further, in FIGS. 2 and 3, 1 is an inorganic filler-containing olefinic polymer layer, and 2 is a metal layer (metal foil). Also,
3 is a thermosetting coating layer with excellent weather resistance. Additionally, 2a and 2b are primer layers (one or both may be absent). Further, 1a is a skin layer, and 1b is a core layer (foam layer). Furthermore, is a laminated metal foil (metal layer), is an inorganic filler-containing olefinic polymer layer, and is a thick cylindrical portion. As is clear from these drawings, the feature of the reflector for a circularly polarized antenna of the present invention is that it has a structure consisting of at least three layers. In addition, the reflector for circularly polarized antennas of the present invention has strong adhesion between the thermosetting coating layer and the metal layer, which has excellent weather resistance, and between the metal layer and the inorganic filler-containing olefinic polymer layer. Primers can also be used to do this. Furthermore, in order to attach the reflector for a circularly polarized antenna of the present invention to a support, a mounting rib may be provided so that an inorganic filler-containing olefin polymer layer can be attached, and reinforcing to reinforce the reflector. You can also add ribs. Furthermore, it is also possible to drill holes in the circularly polarized antenna support obtained by the present invention and attach various support attachment parts using bolts, nuts, etc. Further, the diameter of the reflector for the circularly polarized antenna is usually 60 cm to 120 cm. (G) Method for manufacturing a reflector for a circularly polarized antenna There are various methods for manufacturing the reflector for a circularly polarized antenna of the present invention. A typical method is to use metal foil (metal layer) as described below.
A paint is applied to one side of the metal foil (laminated metal foil) having a coating layer, and an olefinic polymer containing an inorganic filler is injected onto the other side (the side without the coating layer) as described below. Another method is to mold it. When manufacturing laminated metal foil, if the adhesion (adhesion) between the paint used and the metal foil is not fully satisfactory, a primer (adhesive agent) may be applied to one side of the metal foil in advance. This primer layer may be coated with paint. Furthermore, an inorganic filler-containing olefinic polymer is injection molded onto a metal foil or a metal foil coated with a primer as described below, and the resulting molded product is molded without applying a primer and drying. After these treatments, a paint may be applied. By this injection molding, it is possible to manufacture a product (reflector plate for a circularly polarized antenna) that has a core layer (foamed layer) and a skin layer (smooth unfoamed layer) and has no problems in appearance. Manufacturing methods using these molding methods will be explained in more detail. (1) How to apply Sakae 11 material When using a paint that has excellent adhesion to the metal layer, it is sufficient to apply the paint directly to the metal foil. However, when using a paint whose adhesion to metal foil is not fully satisfactory, apply a primer commonly used in the field of paint to one side of the metal foil in advance by gravure coating or bar coating. Apply it and apply it for 50~
Dry at 100℃. Next, paint is applied to the primer surface of the metal foil and allowed to dry. On the other hand, the olefin polymer of the inorganic filler-containing olefin polymer used in injection molding described later on the other surface of the metal foil (the surface not coated with paint) has sufficient adhesion to the metal foil. If this is not possible, apply and dry the primer as described above. Incidentally, the application of the primer and the application of the paint are not special methods, and may be performed by methods generally used in industry. The primer used varies depending on the type of paint and olefin polymer used, but is commonly used in various fields, and includes water-based and solvent-based primers. The types include vinyl, acrylic, polyamide, epoxy, rubber, urethane, and titanium. (2) Production by injection molding method The reflector for a circularly polarized antenna having a skin layer and a core layer made of the inorganic filler-containing olefin polymer of the present invention is produced by injection molding method. As for its manufacturing method, first, a paint layer with excellent weather resistance is coated on one side with a metal layer coated with or without a primer as described above, and insert injection molding is performed during molding of a reflector plate for a circularly polarized antenna. At this time, an inorganic filler-containing olefinic polymer layer is obtained by injection molding. In order for the layer formed by this inorganic filler-containing olefin polymer (a composition of an olefin polymer and an inorganic filler) to constitute a skin layer and a core layer, it is necessary to Blend masterbatch containing foaming agent during coalescence,
Alternatively, the inorganic filler-containing olefin polymer without a blowing agent is first injected into a mold using two injection molding machines, and then the inorganic filler-containing olefin polymer without a blowing agent is injected into a mold. The inorganic filler-containing olefin polymer was injected before the inorganic filler-containing olefin polymer to which the foaming agent was added (compounded) through the nozzle of another injection molding machine before the central part of the polymer solidified. By injecting into the center of the polymer, a skin layer obtained from the inorganic filler-containing olefin polymer that was first injected and a skin layer obtained from the inorganic filler-containing olefin polymer that was injected later. The obtained core layer (foamed layer) can be constructed. To carry out insert injection molding, the metal layer described above is inserted between the male molds of the injection molding machine (the paint layer with excellent weather resistance is inserted on the male mold side). , close the mold. By filling the mold with an inorganic filler-containing olefin polymer through the gate of the mold, cooling it, and then opening the mold, the desired reflector for a circularly polarized antenna can be manufactured. . At this time, the resin temperature for injection molding is higher than the melting point of the inorganic filler-containing olefin polymer used, and the temperature at which the added chemical blowing agent decomposes or the physical blowing agent The temperature is higher than the vaporization temperature, but lower than the thermal decomposition temperature of the olefin polymer. When using a propylene polymer as the olefin polymer, insert injection molding is carried out at a temperature of 170 to 290°C.
It is desirable to carry out the test in a temperature range of On the other hand, when an ethylene polymer is used as the olefin polymer, insert injection molding is carried out at a temperature in the range of 120 to 250°C. In addition, if the gauge pressure at the nozzle part of the cylinder of the injection molding machine is 40Kg/cm ² or more, the injection pressure is
Not only can the inorganic filler-containing olefinic polymer be shaped into a shape almost similar to the shape of the mold, but also a product with good appearance can be obtained. Injection pressure is generally 40 to 140
Kg/cm ² , preferably 70 to 120 Kg/cm ² . As mentioned above, the method of applying paint to the metal foil of the molded product manufactured by the injection molding method and not coated with paint is not a special method. Although there are methods using a roll coater and the like, a method using a spray gun is industrially effective, and a method using a robot is particularly preferred. [] EXAMPLES AND COMPARATIVE EXAMPLES The present invention will be explained in more detail with reference to Examples below. In Examples and Comparative Examples, the radio wave reflectance was measured as a microwave reflection coefficient using a rectangular waveguide and using a constant voltage wave ratio when the tip of the waveguide was short-circuited. In addition, the weather resistance test was conducted using a Sunshine Carbon Weather Meter, with a black panel temperature of 83°C and a due cycle of 12 minutes/12 minutes.
The surface appearance (adverse changes such as discoloration, fading, gloss change, crazing, blistering, peeling of metal foil, and cracks) after 2000 hours under the conditions of (60 minutes of irradiation) was evaluated.
In addition, heat cycle tests test samples at 80°C.
After 2 hours of exposure to temperature, the temperature was gradually cooled to -45°C over 4 hours, exposed to this temperature for 2 hours, and then gradually heated to 80°C over 4 hours, and the cycle continued.
After the test was repeated 100 times, the appearance of the surface of the sample was evaluated in the same manner as in the weather resistance test. In addition, the peel strength is greater than the width of the manufactured reflector for circularly polarized antennas.
A 15 mm test piece was cut out, and the strength was evaluated when the metal layer was peeled off at 180 degrees at a peeling speed of 50 mm/min in accordance with ASTMD-903. Furthermore, bending stiffness was measured according to ASTM D-790, and thermal expansion coefficient was measured according to ASTM D-696. The types and physical properties of the paints, olefin polymers, inorganic fillers, blowing agents, and metal foils that constitute the coating layers used in Examples and Comparative Examples are shown below. [(A) Paint] As the paint, a two-component polyurethane resin (manufactured by Nihon Yushi Co., Ltd., trade name: Hi-urethane, hereinafter referred to as "U paint") was used. [(B) Olefin polymer] As an olefin polymer, MFI is 0.7g/
A propylene-ethylene block copolymer (ethylene content: 10.5% by weight, hereinafter referred to as "PP(B)") with a 10% ethylene content was used. [(C) Inorganic filler] As the inorganic filler, talc (aspect ratio: about 7) having an average particle size of 3 microns and mica (aspect ratio: about 8) having an average particle size of 3 microns were used. [(D) Blowing agent] Sodium bicarbonate [hereinafter referred to as "blowing agent (A)"] and azodicarboxylic acid amide [hereinafter referred to as "blowing agent (B)]" were used as blowing agents. [(E) Metal Foil] Aluminum (hereinafter referred to as "Al"), brass and silver foils each having a thickness of about 20 microns were used. Examples 1 to 4, Comparative Example 1 An epoxy resin primer (manufactured by Dainippon Toyo Co., Ltd., trade name: V Flon Primer) was applied to one side of the metal foils whose types are shown in Table 1, each having a dry thickness of 20 microns. Apply it and let it dry.
A paint whose type is shown in Table 1 (U paint) was applied to the primer-coated surface of the obtained metal foil to a dry thickness of 30 microns, and was left overnight. A urethane primer (trade name: Adcoat 335, manufactured by Toyo Morton Co., Ltd.) was applied to the other side of the metal foil having the coating layer thus obtained, so that the dry thickness was 15 microns. Dry. In addition, inorganic fillers and olefin polymers (the types of each inorganic filler and olefin polymer and the content of the inorganic filler in the composition are shown in Table 1). blowing agent in the composition
0.3% by weight for (B) and 0.5% for blowing agent (A)
A foamable composition was prepared by weight percent dry blending. The laminated metal foil produced as described above is molded into one injection molding machine (clamping force: 1500 tons).
(Examples 2 to 4) or two injection molding machines (clamping force 1500 tons), injecting a composition containing no foaming agent from the nozzle head of one of them, Furthermore, by injection molding by injecting a composition containing a foaming agent from the same nozzle head (Example 1 and Comparative Example 1), the mold surface on the movable side of the mold (the olefin polymer layer was formed on the fixed mold surface). ). After closing the mold, the injection pressure is 80Kg/ ^cm2 and the resin temperature is
Under conditions of 270°C, the compositions whose types of olefin resin and inorganic filler and the content of the inorganic filler in the composition are shown in Table 1 are subjected to insert injection molding, and Reflector for a circularly polarized antenna with a bowl-like shape (external diameter 750 mm, height 80 mm) with a wall thickness of 8 mm, a radius of 5 mm on the surface, and an external cylinder (thick cylinder part) with a height of 20 mm as shown in the figure. The board was manufactured. The elastic modulus, average expansion ratio, and linear expansion coefficient of the inorganic filler-containing olefin polymer layer of each circularly polarized antenna reflector obtained as described above, as well as the inorganic filler-containing olefin polymer layer The peel strength of the foil was measured. The results are shown in Table 2.

【table】

[Table] When we measured the radio wave reflectance of each circularly polarized antenna reflector obtained as above, all of them were
It was 98%. Furthermore, a weather resistance test and a heat cycle test were conducted, and all of them except Comparative Example 1 showed discoloration, fading, change in gloss, crazing, etc.
No harmful changes such as blistering, peeling of the metal foil, or cracks were observed. However, in Comparative Example 1, the aluminum foil on the surface corroded. moreover,
The appearance of the reflective plates obtained in all Examples and Comparative Example 1 was good.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view of an antenna to which a typical reflector for a circularly polarized antenna manufactured according to the present invention is attached. Moreover, FIG. 2 is a sectional view of the reflector for the circularly polarized antenna. Furthermore, FIG. 3 is a partially enlarged view of the cross-sectional view. A...Reflector for circularly polarized antenna, B...Converter, C...Converter support rod, D...Reflector support rod, E...Wiring, 1a...Skin layer, 1b
... core layer, 1 ... inorganic filler-containing olefinic polymer layer, 2 ... metal layer (metal foil), 3 ... thermosetting coating layer with excellent weather resistance, 2a ... primer layer, 2b...primer layer,...metal foil coated with paint,...inorganic filler-containing olefinic polymer layer,...thick cylindrical portion.

Claims (1)

[Claims] 1 At least (A) a metal layer having a thermosetting coating layer with excellent weather resistance and (B) an olefinic polymer layer containing an inorganic filler are laminated in sequence, and the thickness of the coating layer is 5 The thickness of the metal layer is 5 microns to 1 mm, and the thickness of the inorganic filler-containing olefinic polymer layer is 500 microns to 15 mm, and the content of the inorganic filler in this layer is This inorganic filler-containing olefinic polymer layer is composed of a skin layer and a core layer, where the skin layer is essentially a non-foamed layer, the core layer is a foamed layer, and the inorganic filler-containing olefinic polymer layer is 10 to 80% by weight. The thickness of the skin layer in the inorganic filler-containing olefin polymer layer is 5 to 50% of the total thickness of the inorganic filler-containing olefin polymer layer.
45%, and the average expansion ratio of the inorganic filler-containing olefinic polymer layer is 1.005 to 1.50.