JPH0144494B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for forming a thermoforming laminate suitable for manufacturing a housing having electromagnetic wave shielding properties by air pressure forming. [Prior Art] Conventionally, in order to manufacture a housing having electromagnetic wave shielding properties, methods such as applying metal spraying to the housing or coating the housing with a conductive paint have been used. However, in the former method, the sprayed metal or alloy tends to peel off from the housing body, and in the latter method, the metal particles contained in the paint undergo changes over time such as oxidation, which deteriorates the electromagnetic wave shielding ability. It was hot. Furthermore, both methods had the disadvantage of being expensive in themselves. Therefore, a method of forming a laminate made by laminating metal foil and resin was proposed, but since the metals used for these laminates are Fe foil and Al foil, the formability is insufficient and only shallow forming is possible. It is something. Therefore, it is preferable that the metal foil used for this laminate has superplasticity, and it is expected that it will be molded integrally with the resin. However, although Zn-Al alloy, Pb-Sn alloy, etc. are known as superplastic alloys, laminates using these superplastic alloys are not yet commercially available, and the forming conditions etc. are not completely clear. The current situation is that this is not the case. [Problems to be Solved by the Invention] When air-pressure forming metal superplastic materials, the forming time is long because the superplastic material exhibits large elongation only below a certain deformation rate.
The forming time for a 1 mm thick plate made of 22% Al alloy is 1 to 3.
It will take about a minute. On the other hand, when molding resin plates for thermoforming, a method is used in which a constant pressure of 3 kg/cm ² is applied while reducing the pressure inside the female mold to remove air, and the molding time is within about 60 seconds (in most cases, within 10 seconds). It's summery. Furthermore, in pressure molding of resin, most of the deformation ends immediately after the start of molding, and the remaining molding time is required to sharpen edges and create fine irregularities. For example, use 2 mm thick acrylic modified PVC (trade name: Kaidatsu, manufactured by Tsutsunaka Plastic Industries Co., Ltd.) to
It took 10 seconds at a temperature of 160°C and a pressure of 5 kg/cm ² to mold a casing of 100 mm, length 200 mm, and depth 35 mm. However, when molding was performed under the above conditions with pressure applied for 2 seconds, the edges were quite rounded, but the shape was a casing, and more than 90% of the deformation had already been completed. As described above, the molding conditions such as molding speed are significantly different between the superplastic material and the thermoforming resin plate. When the above-mentioned laminate is air-formed using the conventional resin molding method, the deformation speed, especially at the initial stage of molding, is too fast compared to the deformation speed at which superplastic alloy sheets exhibit large elongation, resulting in shallow drawing ratios and rounded edges. Although molding is possible in very limited shapes such as molds, the deformation of the superplastic metal is generally not transferred to the resin, and cracks occur in the metal plate after molding, or separation occurs between the resin plate and the metal plate. . Although such cracking and peeling of the metal plate can be prevented by lowering the molding pressure, mold reproducibility becomes insufficient in this case. [Means for Solving the Problem] The present inventors have developed a thermoforming laminate in which superplastic alloys such as Pb-Sn, Pb-Sn-Cd, and Zn-Al are laminated with various thermoforming resins. As a result of repeated forming tests on the plates, we found that during pressure forming of the above laminate plate,
By changing the molding pressure in multiple stages or steplessly,
By setting the initial molding pressure to a lower pressure than the subsequent molding pressure, then increasing the pressure, or increasing the pressure sequentially while performing subsequent molding, we have discovered a completely new and previously unthinkable finding that laminates can be formed well. Obtained. The present invention was completed based on these findings. That is, the present invention focuses on the fact that the deformation rates of superplastic alloy and thermoforming resin are different, and first molds the superplastic alloy at a pressure that allows it to deform, then increases the pressure,
Alternatively, the key point is to mold while increasing the molding temperature and obtain mold reproducibility. Accordingly, in the present invention, the initial forming pressure is meant to be a relatively low pressure at which the superplastic alloy is deformable and the thermoforming resin is preformed. These initial molding pressures and subsequent pressures are achieved by changing the pressure in multiple steps, preferably in two steps, or by changing the pressure steplessly. In the present invention, the superplastic alloy is a two-phase or three-phase or more alloy system with fine crystal grains, so that it can be used at an ambient temperature of 300℃ or less, which is the general molding temperature for thermoplastic resins (thermoforming resins). This refers to something that shows a growth of 100% or more. Specifically, Pb-Sn alloys with a Sn content of 19 to 97.5 wt%, Pn-
It is a Sn-Cd alloy with a Sn content of 10 to 62 wt%,
Cd content 0.5~30wt% or Zn-Al
These include alloys with an Al content of 21 to 23 wt% and those improved by adding Cu, Mg, etc. in an amount of 1% or less. Since the present invention is to form a laminate made by laminating these superplastic alloys and a thermoforming resin into a housing or the like by pressure forming, the superplastic alloy naturally exhibits superplasticity at the molding temperature of the resin. Since it is a plastic material and basically does not need to be rigid, it must be made as thin as possible without holes and must be able to keep up with resin molding.
For this purpose, the thickness of the superplastic alloy plate is 0.3 to 0.01 mm.
It is preferable to set it as approximately. Further, the resin for thermoforming in the present invention must satisfy the main functions when a sheet suitable for pressure molding is used for the casing, and the following resins are suitable. In other words, it is a group consisting of acrylic modified PVC resin or additives added thereto, such as the product name Kaidatsu (trade name: Tsutsunaka Plastic Industries Co., Ltd.), modified olefin resin, or a group consisting of additives added thereto. , for example, a group consisting of the product name Orevikku (Tsutsunaka Plastics Co., Ltd.), aromatic polyether resin, or additives added thereto, such as the product name Noryl (Tsutsunaka Plastics Co., Ltd.), as well as ABC. Examples include resin, PVC, polycarbonate, etc. These thermoforming resin sheets preferably have a thickness of about 0.1 to 10 mm. As shown in the attached FIG. 1, these superplastic alloy plates and thermoforming resin sheets are made by attaching thermoforming resin sheets 2 to both sides of a superplastic alloy plate 1 using an adhesive made of a low melting point thermoplastic resin film or the like. Alternatively, they may be laminated via the adhesive 3 or without any inclusions. Further, the laminate may be one in which a thermoforming resin 2 is laminated only on one side of a superplastic alloy plate 1 via an adhesive or adhesive 3, or without any inclusions, as shown in FIG. . In accordance with the present invention, the laminate as described above is formed at a relatively low initial forming pressure and then subjected to subsequent forming at a pressure higher than the initial forming pressure. As mentioned above, the initial molding pressure is within the range where the superplastic alloy is superplastically modified and the thermoforming resin is preformed, but specifically, if the pressure is less than 0.1 Kg/ ^cm2 , the molding will be insufficient; If it exceeds 5 Kg/cm ² , cracks will occur in the alloy plate, so it is preferably 0.1 to 5 Kg/cm ² . Furthermore, if the amount of deformation of the molded body is large, the deformation of the alloy plate will not follow the deformation of the resin, so it is desirable that the amount of deformation be 3 kg/cm ² or less. Furthermore, if the structure of the laminate is one in which thermoforming resin is laminated on only one side of a superplastic alloy plate, the alloy plate may be less effective at deforming due to the deformation of the resin. It is desirable that the pressure be within cm ² . Furthermore, it is obvious that this initial molding pressure does not necessarily have to be increased pressure, but may be applied by reduced pressure. If the holding time of the initial molding pressure is less than 1 second, the amount of deformation of the laminate will be small and the effect of deforming at low pressure will be insufficient, and if it exceeds 20 seconds, molding will take a long time at low pressure and the mold will deteriorate. Since the laminate is cooled, the mold reproducibility becomes insufficient even if it is subsequently molded under high pressure, so the time is preferably 1 to 20 seconds. Moreover, taking a molding time at a lower pressure than necessary increases the total molding time, which is industrially meaningless. The molding pressure after the initial molding is set to 3 from the viewpoint of mold reproducibility.
It is preferable to set it to Kg/cm ² or more, but depending on the shape and pattern of the mold, it is desirable to set it to 5 Kg/cm ² or more. However, it is not practical to exceed 10 kg/cm ² . For a laminate using a Pb-Sn alloy as a superplastic alloy, it is desirable to use a forming temperature of 120 to 183°C. That is, at temperatures below 120°C, superplasticity is not sufficiently exhibited, and at temperatures above 183°C, the Pb alloy melts. In addition, if you want to obtain sufficient superplasticity due to a large drawing ratio, etc., the temperature of the laminate should be 150℃ to 170℃.
It is more desirable to set the temperature range to . Also,
When using a Pb-Sn-Cd based superplastic alloy, the temperature of the laminate is preferably 110°C to 145°C. That is, at temperatures below 110°C, superplasticity is not sufficiently exhibited, and at temperatures above 145°C, the Pb alloy melts.
Further, when it is desired to obtain sufficient superplasticity due to reasons such as a large drawing ratio, a temperature range of 125 to 135°C is desirable. As can be seen from the above examples, the upper limit of the forming temperature of the laminate is limited by the melting point at which the superplastic metal plate used no longer exhibits superplasticity, or by the transformation point in the case of Zn-Al alloys, and the lower limit is set by the required temperature. The deformation rate is limited by the temperature that satisfies the deformation rate. On the other hand, from the perspective of the thermoplastic resin, the lower limit temperature of the laminate is determined at a temperature at which the resin is insufficiently softened.
In addition, the lower limit of the mold temperature is the temperature at which the resin does not harden sufficiently after molding, or the temperature at which the cooling of the laminate during molding significantly causes a lack of mold reproducibility or uneven thickness, which causes resin shrinkage and mold The upper limit is the temperature that has a significant negative effect on reproducibility. In other words, when using acrylic modified PVC resin as the resin for the laminate, the temperature of the laminate is 110℃ or higher, and the mold temperature is 10~
A temperature of 70°C is appropriate, but it is not limited to this as it may vary depending on various combinations. Similarly, when using modified olefin resin, the appropriate laminate temperature is 140°C or higher and the mold temperature is 30 to 120°C, and when aromatic polyether resin is used, the laminate temperature is 150°C or higher. , mold temperature is 30
A temperature of ~130°C is appropriate, but is not limited to this as it may vary depending on various combinations. [Function] Thus, in the present invention, when forming a thermoforming laminate, the initial forming pressure is set to be lower than the subsequent forming pressure, and then the pressure is increased, or the pressure is increased sequentially while subsequent forming is performed. The superplastic alloy is superplastically deformed, and at the same time, most of the thermoforming resin is deformed and preforming is completed, and the edges of the resin are further sharpened by high pressure loading after that, improving mold reproducibility. will be achieved. Examples are shown below. Example 1 shows an example of two-stage molding, Example 2 shows an example of multi-stage molding, and Example 3 shows an example of stepless molding. In each example, a mold for molding the casing was used, which had a width of 100 mm, a length of 200 mm, a depth of 35 mm, and a portion of the bottom surface had irregularities of about 3 mm in height. Example 1 Thermoforming resins include an acrylic modified PVC resin under the trade name Kaidatsu (Tsutsunaka Plastics Kogyo Co., Ltd.), a modified olefin resin under the trade name Orebitsuku (Tsutsunaka Plastics Kogyo Co., Ltd.), and an aromatic polyether. Polyphenylene oxide, trade name Noryl (manufactured by Tsutsunaka Plastics Co., Ltd.) as a system resin.
was used. As a superplastic alloy, 16 is 0.2mm thick 70
%Pb−30%Sn alloy plate, 10 is 38%Pb−62 with 0.1mm thickness
%Sn alloy plate, 22% 64%Pb−16%Sn−20 with 0.2mm thickness
%Cd alloy plate, 21% 64%Pd−16%Sn−20 with 0.1mm thickness
%Cd alloy plate was used. Also, for all other laminates
A 38%Pb-62%Sn alloy plate with a thickness of 0.2mm was used. As for the lamination method, as shown in Fig. 1, for 1 to 17, 21, and 22, a superplastic alloy is placed between the 2 mm and 1 mm thick adhesive films using a polyolefin-based adhesive film (trade name: Admar Film, manufactured by Tohcello Chemical Co., Ltd.).
VE300). Also 18-20, 23-28
As shown in Figure 2, a superplastic alloy was laminated on one side of the resin. And for 18-20, Admar film VE300 and 2mm thick Kaidatsuku for 23-25
Then, polyolefin adhesive film (Tohcello Chemical Co., Ltd.)
(manufactured by Co., Ltd., product name Admar Film XE070) and thickness
For 26 to 28, Admer film XE070 and 2 mm thick Noryl were used. The results of the examples will now be discussed. Regarding the first stage molding pressure, molding is possible even at a low pressure of 14. In case 1, which is an example of too high
The superplastic deformation of the Pb alloy plate could not keep up with the deformation of the resin, and the Pb alloy plate broke. In addition, when using the lamination method as shown in Figure 2, the deformation of the Pb alloy plate is not sufficient compared to the case as shown in Figure 1, and the deformation of the Pb alloy plate is less than 3 kg/18 as shown in Figure 1.
^cm2 , the Pb plate may break and a gap may form between the resin and the Pb alloy plate, resulting in poor adhesion. In case 8, which is an example in which the first stage molding time was too short, the second stage pressure of 7 kg/cm ² was applied without sufficient primary molding.
There are cracks in the Pb alloy plate. Furthermore, in the case of samples 2, 13, and 19, which are too long examples, the laminate was cooled by the mold before the second stage molding, resulting in insufficient mold reproducibility. The pressure in the second stage is 5Kg/cm ² as shown in Example 20.
The above is sufficient, but as inferred from the case of Example 2, sufficient mold reproducibility cannot be obtained at a pressure as low as 2 Kg/cm ² . Incidentally, Example 1 which is not based on the method of the present invention,
No good results were obtained for 2, 18, and 19.

【table】

[Table] Example 2 1mm thick Kaidatsu and 0.1mm thick Pb-62%
Sn alloy plates are laminated as shown in Figure 1, and the temperature of the laminated plates is
Pressure forming was performed at 160°C and mold temperature of 50°C. The one molded under a pressure of 5Kg/ ^cm2 for 20 seconds is
A crack appeared in the Pb board. However, all molds molded in three stages under the pressure conditions shown in Table 2 had good mold reproducibility.
Moreover, no cracks occurred in the Pb alloy plate.

[Table] Example 3 A 1.5 mm thick Orebic sheet and a 0.1 mm thick Pb alloy plate were laminated as shown in Fig. 2, and pressure forming was performed at a laminate temperature of 160°C and a mold temperature of 80°C. The one molded under a pressure of 7 kg/cm ² for 20 seconds had good mold reproducibility, but the Pb alloy plate had cracks, and the one molded under a pressure of 1 kg/cm ² for 30 seconds had poor mold reproducibility. Although there were no cracks, the mold reproducibility was insufficient. However, when the pressure at the start of molding is 0.1Kg/ ^cm2 , the pressure is gradually increased from 0.1Kg/ ^cm2 to 7Kg/ ^cm2 over 20 seconds at a constant speed to 7Kg/ ^cm2 immediately after the start of molding. The elongation and mold reproducibility of the Pb alloy plate were both good. [Effects of the Invention] According to the present invention as described above, a method for efficiently molding a laminate of a superplastic alloy and a thermoforming resin into the shape of a casing or the like with good mold reproducibility is obtained.
The effect is great.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory cross-sectional views of a thermoforming laminate according to the present invention. 1... Superplastic alloy plate, 2... Resin sheet for thermoforming, 3... Adhesive or adhesive.

Claims (1)

[Claims] 1. When pressure forming a thermoforming laminate made by laminating a superplastic alloy and a thermoforming resin, the initial forming pressure is lower than the subsequent forming pressure, and then the pressure is reduced. A method for forming a thermoforming laminate, characterized by performing subsequent forming while increasing the height or increasing the height sequentially. 2. The method according to claim 1, wherein the molding pressure is varied in multiple stages. 3. The method according to claim 1, wherein the molding pressure is changed steplessly. 4. The method according to any one of claims 1 to 3, wherein the pressure at the initial stage of molding is within a range in which the superplastic alloy is superplastically deformed and the thermoforming resin is preformed. 5. The method according to any one of claims 1 to 4, wherein initial molding is performed at a pressure of 0.1 to 5 kg/cm ² for 1 to 20 seconds, and subsequent molding is performed at a pressure of 3 kg/cm ² or more. 6. The method according to claim 5, wherein the initial molding pressure is 0.1 to 3 Kg/cm ² and the subsequent molding pressure is 5 to 10 Kg/cm ² . 7 The thermoforming laminate is a superplastic alloy plate with thermoforming resin laminated only on one side, and the initial molding pressure is 0.1 to 1.5 Kg/cm ² Claim 1
6. The method according to any one of items 6 to 6. 8 The thermoforming resin is acrylic modified PVC resin, the temperature of the laminate is 110℃ or higher, and the mold temperature is 10~10℃.
The method according to any one of claims 1 to 7, wherein the temperature is 70°C. 9 The thermoforming resin is a modified olefin resin, the temperature of the laminate is 140℃ or higher, and the mold temperature is 30~30℃.
The method according to any one of claims 1 to 7, wherein the temperature is 120°C. 10 The thermoforming resin is an aromatic polyether resin, and the temperature of the laminate is 150℃ or higher and the mold temperature is
The method according to any one of claims 1 to 7, wherein the temperature is 30 to 130°C.