A cover plate production process and cover plate with low millimeter wave transmission attenuation

Abstract

The invention discloses a production process of a cover plate with low millimeter wave transmission attenuation, comprising the following steps: S1: injection molding a panel and a bottom plate respectively; S2: preparing a primer, applying the primer to the inner surface of the panel, and curing to form a primer layer; S3: plating indium on the surface of the primer layer to form an indium plating layer; S4: preparing a protective paint, applying the protective paint to the surface of the indium plating layer, and curing to form a protective layer; S5: compounding the panel with the primer layer, the indium plating layer and the protective layer arranged on the inner surface in sequence with the bottom plate; the indium plating method of the indium plating layer is vacuum evaporation, and the vacuum degree of the vacuum evaporation is not greater than 4'10 ‑2 Pa. The cover plate production process uses the indium plating method of vacuum evaporation to adjust the vacuum degree to less than or equal to 4´10 ‑2 In the range of Pa, a cover plate with a millimeter wave transmission attenuation value less than or equal to 1.7 db can be obtained. A cover plate with low millimeter wave transmission attenuation is also disclosed.

Description

Technical Field

[0001] The invention relates to the field of automobile component manufacturing, and in particular to a cover plate production process and a cover plate with low millimeter wave transmission attenuation. Background Art

[0002] The sensor of the adaptive cruise control system ACC (Adaptivecruise control) is a millimeter-wave radar, which has stronger penetration than infrared and laser sensors and has the characteristics of all-weather operation. Therefore, millimeter-wave radar technology is increasingly used in many fields such as automotive electronics and intelligent transportation, and can detect the presence of target objects, measure distance, speed and direction, etc. A millimeter-wave radar transmitter is commonly installed on the front of the vehicle body, and a cover plate is required on the front of the vehicle head to cover the front end of the millimeter-wave radar transmitter to prevent the influence of bad weather on the millimeter-wave radar. When the millimeter wave penetrates the cover plate, the shielding of the cover plate causes the wave to be attenuated. Therefore, it is necessary to meet the requirements of wave attenuation. The thickness of the cover plate, the thickness and quality of the metal texture decorative coating, and the uniformity of other film layer molding all affect the penetration rate of the millimeter-wave radar.

[0003] In the prior art, the patent with publication number CN102514533A discloses a method for making a car sign that can meet the radar active cruise function, including the following steps: S1: using an injection molding machine to make a transparent polycarbonate plastic sign with a curvature, the thickness of which is 5-6 mm; S2: UV spraying to obtain a transparent plastic sign with a metallic texture and a protective layer; S3: sputtering one side of the transparent plastic sign obtained in S2 to form an indium metal film, the layer thickness of which is 15-20 microns; S4: casting the surface of the indium-plated plastic sign to form a plastic base. The car sign is produced by injection molding, UV spraying, vacuum ion sputtering indium plating, and secondary injection molding of the car sign base, and then the sign is equipped on the car model. The attenuation value is less than 2.0DB. The sign needs high-temperature secondary injection molding and vacuum protection. This process is more complicated.

[0004] Therefore, it is necessary to improve the sign production process in the prior art. Summary of the invention

[0005] One of the purposes of the present invention is to overcome the defects in the prior art and provide a cover plate production process with low millimeter wave transmission attenuation.

[0006] In order to achieve the above process effect, the technical solution of the present invention is: a cover plate production process with low millimeter wave transmission attenuation, comprising the following steps:

[0007] S1: Injection molding of the front panel and the bottom panel respectively;

[0008] S2: preparing a primer, applying the primer to the inner surface of the panel, and curing to form a primer layer;

[0009] S3: indium is plated on the surface of the primer layer to form an indium-plated layer;

[0010] S4: preparing a protective paint, applying the protective paint to the surface of the indium-plated layer, and curing to form a protective layer;

[0011] S5: Compounding the panel having the primer layer, the indium plating layer and the protective layer sequentially disposed on the inner surface with the base plate;

[0012] The indium plating method of the indium plating layer is vacuum evaporation, and the vacuum degree of the vacuum evaporation is not greater than 4×10 -2 Pa.

[0013] In step S1, the thickness of the panel is 5-6 mm, and the thickness of the base plate is 1-2 mm. The panel and base plate are compounded by glue. Furthermore, the vacuum degree of vacuum evaporation is 0.95×10 -2 ~4×10 -2 Pa.

[0014] The maximum temperature of the vacuum evaporation process in step S3 is 600~800℃. The vacuum evaporation is carried out under high temperature conditions. Indium materials are easy to react with a small amount of oxygen in the air to produce indium oxide. The conductivity of indium oxide affects the penetration rate of millimeter wave radar. The smaller the vacuum degree, the more conducive to the wave transmission of the indium plating layer. Combined with the stability, efficiency, limitations of the equipment operation and the conditions of the indium plating process, in order to obtain the indium plating layer with the optimal millimeter wave transmission attenuation value, the preferred technical solution is that the vacuum degree of the vacuum evaporation is 0.95×10 -2 ~1.4×10 -2 Pa.

[0015] In order to optimize the thickness of the primer layer, the indium plating layer and the protective layer, the preferred technical solution is that the thickness of the indium plating layer is 0.1-0.5 μm, the thickness of the primer layer is 12-18 μm, and the thickness of the protective layer is 18-24 μm. The primer layer and the protective layer are sprayed by compressed air or curtain coating. In order to achieve a better paint layer thickness and facilitate the adhesion of the indium plating layer, the primer layer and the protective layer are further sprayed by compressed air.

[0016] The preferred technical solution is that the indium material coated in the vacuum evaporation passes through the first preheating section, the second preheating section and the evaporation section in sequence. A small amount of impurities, such as water and oil, may adhere to the surface of the target material during vacuum evaporation. The first preheating section is to clean the impurities on the surface of the target material; the second preheating section is a transition section before the evaporation section to pre-melt the indium material to prevent the temperature of the evaporation section from being too high and too fast, resulting in uneven thickness of the indium coating layer, which in turn affects the adhesion of the indium coating layer to the primer layer and also affects the penetration rate of micron waves. Furthermore, the temperature of the first preheating section is 300~320℃; the temperature of the second preheating section is 430~560℃. After the evaporation section, the vacuum evaporation chamber also needs to clean the residual target material on the surface of the heating source. The first cleaning section and the second cleaning section are set up to make full preparations for the evaporation of the next workpiece so as not to affect the performance of the next workpiece. Furthermore, the power supply of the first cleaning section is 12.15~12.69kW, and the cleaning holding time is 12~16s; the power supply of the second cleaning section is 13.5~14.04kW, and the cleaning holding time is 2~4s.

[0017] In order to fully evaporate the indium material and obtain an indium-plated layer with uniform thickness and stable performance, the preferred technical solution is that the voltage of the evaporation section is 3.6~3.9V, the current is 0.65~0.67kA, and the evaporation time is 12~16s.

[0018] In order to improve the cleanliness of the indium material surface in the evaporation section and maintain the performance stability of the indium material, the preferred technical solution is that the voltage of the first preheating section is 2.7~2.9V, the current is 0.36~0.39kA, and the preheating holding time is 55~65s; the voltage of the second preheating section is 3.0~3.3V, the current is 0.46~0.48kA, and the preheating holding time is 21~25s. If the time of the first preheating section is too long, it is easy to cause oxidation of the target material and affect the radar transmittance of the indium-plated layer; if the time of the first preheating section is too short, the moisture, oil stains, etc. attached to the surface of the target material will not evaporate sufficiently, which is easy to affect the adhesion and transmittance of the indium-plated layer. If the time of the second preheating section is too long, the target material will be lost and it will be easily oxidized at a higher temperature, affecting the uniformity, stability and transmittance of the indium-plated layer; if the time of the second preheating section is too short, it will affect the sputtering of the target material, insufficient sputtering or uneven sputtering layer.

[0019] In order to optimize the primer and obtain a primer layer with uniform thickness and good performance, and to fully cure the primer layer, the preferred technical solution is that the primer layer is an acrylic resin UV paint, the leveling time at room temperature is 42-46s, the IR leveling temperature is 57-63°C, the IR leveling time is 5-6min; the UV energy is 700-900mJ / cm 2 , UV power density is 90~120mkW / cm 2. The volatile substances in the room temperature leveling volatilize the primer to prevent the subsequent IR leveling and curing from being affected, and improve the flatness and adhesion of the primer layer. Furthermore, the acrylic resin UV paint is an epoxy-modified acrylic resin UV paint. The primer has hydrogen bonding effects of functional groups such as ether bonds and hydroxyl groups, which improves the adhesion of the primer layer to the surface of the cover plate, and at the same time improves the adhesion to the indium plating layer. The cured and cross-linked network structure increases the contact area with indium, further improves the adhesion of the indium plating layer, and makes the primer layer and the indium plating layer fit closely. The viscosity of the primer is 8~10s. The viscosity of the primer affects the uniformity of leveling and the degree of curing of the primer. When the curing is incomplete, it affects the degree of cross-linking of the primer and has a negative effect on the adhesion of the indium plating layer.

[0020] The cover plate product is assembled on the grille in front of the radiator. The panel shape of the cover plate is made to imitate the grille shape. The color paint used in the protective paint is selected according to the color requirements of the car appearance. In order to optimize the composition of the protective layer, obtain a protective layer with uniform layer thickness and stable film performance, and improve the barrier performance of the indium-plated layer, the preferred technical solution is that the paint main agent of the protective paint is an acrylic resin paint, and the mass ratio of the paint main agent, curing agent and diluent in the protective paint is 10: (0.8~1.1): (8~9). Furthermore, the paint main agent of the protective paint is an epoxy-modified acrylic resin paint. The protective paint also has hydrogen bonding effects of functional groups such as ether bonds and hydroxyl groups, which improves the adhesion of the protective paint on the indium-plated layer, and the three-dimensional structure polymer obtained by the cross-linking reaction of the paint main agent and the curing agent effectively blocks the diffusion of indium material to the surface of the protective layer, and also isolates the outside air or water vapor from penetrating into the interior of the protective layer. The viscosity of the protective paint is 18~21s. The viscosity of the protective paint affects the uniformity of leveling and the degree of curing of the protective paint. When the curing is incomplete, it affects the degree of cross-linking of the protective paint and has a negative impact on the insulation performance of the indium-plated layer. Too much curing agent shortens the life of the paint main agent, the hardness of the cured paint film is large, the performance of the paint film decreases, and has a negative impact on the barrier performance of the indium-plated layer; too little curing agent causes incomplete curing, the resulting paint film is easy to fall off, and affects the barrier performance of the protective layer. Too much diluent is not conducive to the curing of the paint film and affects the performance and appearance of the paint film; too little diluent is not conducive to the formation of a film layer of uniform thickness, affects the uniform distribution of the protective paint components, and thus affects the degree of curing of the paint film.

[0021] In order to fully cure the protective layer and form a stable protective layer, the preferred technical solution is that the room temperature leveling time of the protective layer is 42-46 seconds, the baking temperature is 75-83°C, and the baking time is 40-65 minutes.

[0022] The second object of the present invention is to overcome the defects in the prior art and provide a cover plate with low millimeter wave transmission attenuation, which is manufactured by the above-mentioned cover plate production process with low millimeter wave transmission attenuation.

[0023] The advantages and beneficial effects of the present invention are:

[0024] The cover plate production process uses the indium plating method of vacuum evaporation to adjust the vacuum degree to less than or equal to 4×10 -2 Within the Pa range, a cover plate with a millimeter wave transmission attenuation value less than or equal to 1.7db can be obtained; the inner surface of the panel includes a primer layer, an indium plating layer and a protective layer in sequence, which enhances the adhesion and stability of the indium plating layer. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0026] Primer viscosity test

[0027] The temperature was 22~26℃, the humidity was 55~65%, and the Iwata No. 2 cup was used to measure the time from the fluid outflow line to the appearance of a fracture.

[0028] Testing of viscosity of protective paint

[0029] The temperature is 22~26℃, the humidity is 55~65%, and the Ford No. 4 cup is used to measure the time from the fluid outflow line to the appearance of a fracture.

[0030] The primer is produced by Shanghai Feikai Optoelectronic Materials Co., Ltd., with the brand name KY40C2-18;

[0031] The paint is produced by Momentive High-Tech Materials Group, brand name Somaprim 00325 Black; the curing agent brand name is HSDC16; the diluent brand name is TH1309;

[0032] SilFORT UVHC5000 UV-curing hardening paint is produced by Momentive High-Tech Materials Group.

[0033] Example 1

[0034] Embodiment 1 The production process of a cover plate with low millimeter wave transmission attenuation comprises the following steps:

[0035] S1: The front panel and the bottom panel are respectively injection molded, the thickness of the front panel is 5.27mm, the thickness of the bottom panel is 1.58mm, and the material of the front panel and the bottom panel is PC;

[0036] S2: Prepare the primer and spray it on the inner surface of the panel by compressed air spraying. The primer layer is a UV paint with a viscosity of 9s, the spraying pressure is 0.42Mpa, the leveling time at room temperature is 45s, the IR leveling temperature is 62℃, and the IR leveling time is 5.6min; the UV energy is 800mJ / cm 2 , UV power density is 105mkW / cm2 , and solidifies to form a primer layer.

[0037] S3: Indium is plated on the surface of the primer layer to form an indium-plated layer;

[0038] S4: The mass ratio of paint main agent, curing agent and diluent in the protective paint is 10:1:9. The protective paint is a color paint with a viscosity of 20s. The protective paint is sprayed on the surface of the indium-plated layer by compressed air spraying. The spraying distance is 15cm, the spray gun caliber is 1.2mm, and the spraying air pressure is 3.5kg / cm 2 The leveling time of the protective paint at room temperature is 45s, the baking temperature is 82°C, the baking time is 60min, and the protective layer is formed after solidification;

[0039] S5: Compounding the panel with the primer layer, the indium plating layer and the protective layer on the inner surface in sequence with the bottom plate, and using ITkW structural adhesive on the compound surface;

[0040] The indium plating method of the indium plating layer is vacuum evaporation, and the vacuum degree of vacuum evaporation is 0.98×10 -2 Pa.

[0041] In the vacuum evaporation, the coated indium material passes through the first preheating section, the second preheating section and the evaporation section in sequence.

[0042] The voltage of the first preheating stage is 2.8V, the current is 0.37kA, and the preheating holding time is 60s; the voltage of the second preheating stage is 3.2V, the current is 0.47kA, and the preheating holding time is 23s. The voltage of the evaporation stage is 3.8V, the current is 0.66kA, and the evaporation time is 15s.

[0043] The layer thickness of the indium plating layer is 0.42 μm, the layer thickness of the primer layer is 13.34 μm, and the layer thickness of the protective layer is 22.67 μm.

[0044] After step S4, a hardening coating is sprayed on the outer surface of the panel to further improve the wear resistance, UV resistance and weather resistance of the cover plate.

[0045] The cover plate with low millimeter wave transmission attenuation is manufactured by the above-mentioned cover plate production process with low millimeter wave transmission attenuation.

[0046] Example 2

[0047] Example 2 is based on Example 1, except that the vacuum degree of vacuum evaporation is 4×10 -2 Pa.

[0048] Example 3

[0049] Example 3 is based on Example 1, except that the vacuum degree of vacuum evaporation is 2.1×10 -2 Pa.

[0050] Example 4

[0051] Example 4 is based on Example 1, except that the indium material coated in the vacuum evaporation is sequentially passed through a preheating section and an evaporation section, the voltage of the preheating section is 2.9V, the current is 0.39kA, and the preheating holding time is 75s. The process parameters of the evaporation section remain unchanged.

[0052] Example 5

[0053] Example 5 is based on Example 1, except that the voltage of the evaporation section is 3.8 V, the current is 0.72 kA, and the evaporation time is 15 s.

[0054] Example 6

[0055] Example 6 is based on Example 1, except that the voltage of the evaporation section is 3.8 V, the current is 0.6 kA, and the evaporation time is 15 s.

[0056] Examples 7 and 8

[0057] Example 7 is based on Example 1, except that the thickness of the protective layer is 12 μm;

[0058] Example 8 is based on Example 1, except that the layer thickness of the protective layer is 32 μm.

[0059] Examples 9 and 10

[0060] Example 9 is based on Example 1, except that the baking temperature of the protective layer is 102° C. and the baking time is 60 min.

[0061] Example 10 is based on Example 1, except that the baking temperature of the protective layer is 65° C. and the baking time is 60 min.

[0062] Embodiment 11

[0063] Example 11 is based on Example 1, except that the mass ratio of the paint base, the curing agent and the diluent in the protective paint of the protective layer is 10:1:11.

[0064] Example 12

[0065] Example 12 is based on Example 1, except that the room temperature leveling time of the primer layer is 20 seconds.

[0066] Example 13

[0067] Example 13 is based on Example 1, with the difference that the layer thickness of the primer layer is 10 μm.

[0068] Comparative Example 1

[0069] Comparative Example 1 is based on Example 1, except that the vacuum degree of vacuum evaporation is 5×10 -2 Pa.

[0070] Comparative Example 2

[0071] Comparative Example 2 is based on Example 1, except that the vacuum degree of vacuum evaporation is 0.9×10 -2 Pa.

[0072] 1. Wave Transparency

[0073] Automobile radar attenuation detector KEYCOM-SM5899;

[0074] The test results of the wave transmission test of the cover plates of Examples 1 to 6 and the comparative example are as follows:

[0075]

[0076] Products with attenuation values ​​less than or equal to 2DB are qualified. For products with higher requirements for wave transmittance, the attenuation value must be less than or equal to 1.7DB.

[0077] Only preheating in the first stage affects the deposition rate of the target material in the evaporation stage and the performance of the indium coating layer, and easily leads to insufficient volatilization of the target material.

[0078] Increasing the current in the evaporation stage can accelerate the deposition rate, but too large a current can easily cause oxidation or coking of the target material, which has a negative impact on the indium plating layer. Compared with Example 1, the attenuation value of Example 5 is higher.

[0079] The current in the evaporation stage is too small, which is not conducive to the full volatilization of the target material, affects the thickness and distribution uniformity of the indium plating layer, makes the indium plating layer crafts unqualified, and affects the subsequent cleaning and the next process. Compared with Example 1, the attenuation value of Example 6 is higher.

[0080] 2. Barrier properties

[0081] The samples of Examples 1 and 7 to 11 were coated with a protective layer after the indium layer was plated. The samples were immersed in a 3.5% NaCl electrolyte solution for 3 hours, and the impedance value of the protective layer was detected. The impedance value of the protective layer at low frequency was 10 8 Ω or above, the barrier performance of the protective layer is good, otherwise the barrier performance of the protective layer is unqualified.

[0082] The test results of the barrier performance test of the protective layer of Example 1 and Examples 7 to 11 are as follows:

[0083]

[0084] The protective layer of Example 8 was cracked and failed; the protective layer of Example 9 had shrinkage holes and shrinkage, so it was failed; and Example 10 was not completely cured and the protective layer fell off.

[0085] 3. Adhesion performance testing

[0086] The adhesion test of the indium coating on the primer layer is to draw a vertical line every 1mm*1mm on the dried paint film, and judge the adhesion of the paint film according to the extension of the scratch. The adhesion is divided into 0~4 levels, 0 level means that there are small pieces of paint peeling at the cut and intersection, and the actual damage in the grid area is less than 5%; 1 level means that the edge of the cut and intersection is peeled off 5~15%; 2 level means that the edge of the cut and intersection is partially peeled off or a large area is peeled off, and the peeled area is 16~35%; 3 level means that part of the square is peeled off, and the peeled area is 36~65%; 4 level means that the peeled area is greater than 65%. The lower the adhesion level, the better the adhesion of the indium coating on the paint film.

[0087] The test results of the adhesion test of the indium-plated layer on the primer layer of Example 1 and Examples 12-13 are as follows:

[0088]

[0089] Adhesion level 0-1 is qualified. Compared with Example 1, the adhesion performance of the indium-plated layer in Examples 4-6 is reduced. Compared with Example 1, the short leveling time at room temperature in Example 12 will affect the volatilization of the solvent in the primer, the curing of the primer and the performance of the primer layer, and thus affect the adhesion of the indium-plated layer. Compared with Example 1, the thinning of the primer layer in Example 13 has a negative effect on the adhesion of the indium-plated layer.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for producing a cover plate with low millimeter wave transmission attenuation, characterized in that: The following steps are involved: S1: Injection molding of the front panel and the bottom panel respectively; S2: preparing a primer, applying the primer to the inner surface of the panel, and curing to form a primer layer; S3: indium is plated on the surface of the primer layer to form an indium-plated layer; S4: preparing a protective paint, applying the protective paint to the surface of the indium-plated layer, and curing to form a protective layer; S5: Compounding the panel having the primer layer, the indium plating layer and the protective layer sequentially disposed on the inner surface with the bottom plate; The indium plating method of the indium plating layer is vacuum evaporation, and the vacuum degree of the vacuum evaporation is not greater than 4×10 -2 Pa; The thickness of the indium plating layer is 0.1-0.5 μm, the thickness of the primer layer is 12-18 μm, and the thickness of the protective layer is 18-24 μm; In the vacuum evaporation, the indium material is sequentially passed through a first preheating section, a second preheating section and an evaporation section; The voltage of the first preheating section is 2.7~2.9V, the current is 0.36~0.39kA, and the preheating holding time is 55~65s; the voltage of the second preheating section is 3.0~3.3V, the current is 0.46~0.48kA, and the preheating holding time is 21~25s; The voltage of the evaporation section is 3.6-3.9 V, the current is 0.65-0.67 kA, and the evaporation time is 12-16 s.

2. The process for producing a cover plate with low millimeter wave transmission attenuation according to claim 1, characterized in that: The vacuum degree of the vacuum evaporation is 0.95×10 -2 ~1.4×10 -2 Pa.

3. The process for producing a cover plate with low millimeter wave transmission attenuation according to claim 1, characterized in that: The primer layer is an acrylic resin UV paint, the leveling time at room temperature is 42-46 seconds, the IR leveling temperature is 57-63°C, the IR leveling time is 5-6 minutes; the UV energy is 700-900 mJ / cm 2 , UV power density is 90~120mkW / cm 2 .

4. The process for producing a cover plate with low millimeter wave transmission attenuation according to claim 1, characterized in that: The paint main agent of the protective paint is acrylic resin paint, and the mass ratio of the paint main agent, curing agent and diluent in the protective paint is 10: (0.8-1.1): (8-9).

5. The process for producing a cover plate with low millimeter wave transmission attenuation according to claim 4, characterized in that: The protective layer has a room temperature leveling time of 42 to 46 seconds, a baking temperature of 75 to 83° C., and a baking time of 40 to 65 minutes.

6. A cover plate with low millimeter wave transmission attenuation, characterized in that: The cover plate with low millimeter wave transmission attenuation is manufactured by the production process of the cover plate with low millimeter wave transmission attenuation according to any one of claims 1 to 5.

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