JP7135393B2 - composite laminate - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a composite laminate, and more particularly to a composite laminate that has excellent adhesion bendability or that can be formed at a negative angle.

Generally, steel plates are used as outer plates of automobiles, and aluminum plates are also used for the purpose of weight reduction (Patent Document 1).

In addition, in order to use a steel plate or an aluminum plate as an outer panel of an automobile, it is necessary to obtain a crimped joint with good adhesion (Patent Document 2).

JP 2008-101239 A JP-A-2005-28368

However, if the plate thickness of the steel plate or aluminum plate is reduced for weight reduction, the bending rigidity (tension rigidity) is lowered and a high-class feeling cannot be obtained. The bending stiffness when subjected to bending in the out-of-plane direction is represented by the product of the elastic modulus of the material and the geometrical moment of inertia I of the shape. The modulus of elasticity is a material-specific value, and the geometrical moment of inertia I is given by the following formula:
I=b×t ³ /12
(Wherein, b is the width and t is the plate thickness)
and is proportional to the cube of the plate thickness.

In addition, in order to obtain a crimped joint with good adhesion by hemming or to perform negative angle forming, there is a problem that a complicated process and a special mold are required, resulting in an increase in cost.

The gist of the present disclosure is as follows.
(1) The composite laminate of the present disclosure includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100° C. or more and less than 225° C.,
The resin layer has a melting point higher than the melting point of the adhesive layer,
A ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The plate thickness of the whole is 0.8 mm or more.
(2) In the composite laminate according to (1) above, the ratio of the total thickness of the resin layers to the total thickness of the metal layers is greater than 1.00.
(3) The composite laminate described in (1) or (2) above has a five-layer structure of metal layer/adhesive layer/resin layer/adhesive layer/metal layer.

According to the composite laminate of the present disclosure, since it is possible to reduce the weight, it is possible to increase the overall plate thickness and obtain good bending rigidity, without requiring complicated processes or special molds. It is possible to obtain a good crimped joint and perform negative angle forming.

FIG. 1 is a schematic cross-sectional view of a composite laminate having a five-layer structure. FIG. 2 is a schematic cross-sectional view of the composite laminated plate of the outer plate after hemming with the inner plate arranged. FIG. 3 is a schematic cross-sectional view of the hemmed composite laminate of FIG. 2 after heat treatment and cooling. FIG. 4 shows the cross-sectional shape, geometrical moment of inertia, and occupied area (volume ), and a comparison of cross-sectional efficiency of member stiffness. FIG. 5 is a schematic cross-sectional view illustrating a method of evaluating bending stiffness. FIG. 6 is a side view photograph of the hemmed composite laminate. FIG. 7 is a side view photograph of the hemmed composite laminate. FIG. 8 is a side view photograph of the hemmed metal plate. FIG. 9 is a schematic diagram illustrating hemming by press bending. FIG. 10 is a schematic diagram illustrating hemming by roller hem. FIG. 11 is a side view photograph of the composite laminate after heat treatment and cooling to room temperature. FIG. 12 is a side view photograph of the composite laminate subjected to heat treatment and cooling after hemming. FIG. 13 is a side view photograph of the composite laminate subjected to heat treatment and cooling after hemming. FIG. 14 is a simulation analysis model. FIG. 15 shows simulation results. FIG. 16 shows simulation results. FIG. 17 is an analysis model of the inside of the bend. FIG. 18 is an analysis model of the outside of bending. FIG. 19 is a contour diagram showing the amount of displacement obtained by analyzing the thermal contraction of the model of FIG. 17 . FIG. 20 is a contour diagram showing the amount of displacement obtained by analyzing the thermal contraction of the model of FIG. 18 . FIG. 21 is a graph showing the closing angle of the in-bend R according to the ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer. FIG. 22 is a graph representing bending stiffness.

The composite laminate of the present disclosure includes a structure in which a resin layer is sandwiched between metal plates via an adhesive layer. The number of layers included in the composite laminate is not particularly limited, and the composite laminate can have any desired configuration as long as it includes a structure in which a resin layer is sandwiched between metal plates via an adhesive layer. For example, as shown in the schematic cross-sectional view of FIG. 1, the composite laminate 100 may have a five-layer structure of metal layer 10/adhesive layer 30/resin layer 20/adhesive layer 30/metal layer 10. It may have a structure in which at least one of a metal layer, an adhesive layer, and a resin layer is added to the five-layer structure, or may further include a net-like wire layer formed in a net shape using a wire. For example, the composite laminate may have a seven-layer structure of metal layer/adhesive layer/reticular wire layer/resin layer/reticular wire layer/adhesive layer/metal layer. The composite laminate preferably has a five-layer structure of metal layer/adhesion layer/resin layer/adhesion/metal layer.

According to the composite laminate of the present disclosure, heat treatment and cooling are performed after bending to further reduce the inner bending angle (hereinafter referred to as bending angle) formed by bending in hemming or forming of hat-shaped steel. Therefore, it is possible to obtain a crimped joint or negative angle structure with improved adhesion between the inner plate and the outer plate without requiring a complicated process or a special mold.

The total thickness of the composite laminate is 0.8 mm or more, preferably 1.0 mm or more, more preferably 1.2 mm or more, and still more preferably 1.4 mm or more. When the composite laminate has a plate thickness within the above range, it is possible to ensure bending rigidity and enhance the appearance of the outer plate.

The total thickness of the metal layers included in the composite laminate is preferably 0.03-0.40 mm, more preferably 0.05-0.20 mm, still more preferably 0.07-0.15 mm.

The total thickness of the resin layers included in the composite laminate is preferably 0.06-0.80 mm, more preferably 0.10-0.50 mm, still more preferably 0.14-0.30 mm.

When the metal layer and the resin layer have thicknesses within the above range, the weight of the composite laminate can be reduced and the flexural rigidity can be further improved.

The ratio of the total thickness of the resin layers provided in the composite laminate/the total thickness of the metal layers provided in the composite laminate is preferably greater than 1.00 and 6.00 or less, more preferably 1.50 or more and 5.50 or less, and further It is preferably 1.75 or more and 5.00 or less, and more preferably 2.00 or more and 4.00 or less.

When the metal layer and the resin layer have the ratio of the thickness of the resin layer/thickness of the metal layer, the weight of the composite laminate can be further reduced and the bending rigidity can be further improved, and the composite laminate has better adhesion. It is possible to obtain a crimped joint and to perform negative angle forming more easily.

The adhesive layer is composed of an adhesive, and the adhesive has a melting point of 100°C or higher and lower than 225°C. The adhesive preferably has a melting point of 180° C. or lower, more preferably 170° C. or lower, and even more preferably 160° C. or lower.

The adhesive is preferably at least one of a thermocompression-type modified polypropylene adhesive, a thermoplastic resin adhesive, an elastomer adhesive, and an inorganic adhesive. Thermocompression modified polypropylene adhesives may have a melting point of about 160°C to 170°C.

In general, when manufacturing an outer panel for an automobile, the inner panel is placed along the edge of the outer panel so as to contact the outer panel, and the outer panel is hemmed to the outer panel so that the outer panel is in close contact with the inner panel. Machining is performed to form a crimped joint to seal the outer plate to the inner plate. Furthermore, the outer plate having the crimped joint is subjected to a baking coating treatment (BH treatment) at 100 to 225° C., especially 170 to 180° C. for 20 to 30 minutes.

In the composite laminate of the present disclosure, since the adhesive of the adhesive layer has a melting point within the above range, the fluidity of the adhesive is increased in the BH treatment process accompanied by heating, and the metal layer and the resin during hemming. The stress generated between layers can be relaxed, and the bending angle formed by the hemming process can be further closed without external force in the subsequent cooling process, so a crimped joint with good adhesion can be obtained. . Composite laminates of the present disclosure may be subjected to a simple heat treatment instead of or in addition to the BH treatment step. The temperature in the BH treatment step or heat treatment is preferably above (melting point -20°C) of the adhesive and below the melting point of the resin layer. The lower limit of the temperature in the BH treatment step or heat treatment is more preferably at least the melting point of the adhesive, still more preferably higher than the melting point of the adhesive. When performing press working or flanging, preferably, similar BH treatment is performed as heat treatment.

The resin layer is made of resin. The resin of the resin layer has a melting point higher than the melting point of the adhesive of the adhesive layer, preferably 20° C. or more higher than the melting point of the adhesive of the adhesive layer. The resin of the resin layer is preferably thermoplastic. The resin of the resin layer preferably has a melting point higher than 225°C, more preferably 250°C or higher, even more preferably 270°C or higher, and even more preferably 290°C or higher. When the resin of the resin layer has a melting point within the above range, it is possible to prevent the resin layer from melting during heat treatment.

The resin of the resin layer is preferably at least one of polyamide 6 (PA6), acetylcellulose, polybutylene terephthalate, polyamide 66 (PA66), polyethylene terephthalate, polyphenylene sulfide, and polyamideimide. Polyamide 6 (PA6) has a melting point of about 225°C; acetylcellulose has a melting point of about 230°C; polybutylene terephthalate has a melting point of about 245°C; polyamide 66 (PA66) has a melting point of about 265°C; Melting points, polyphenylene sulfide may have a melting point of about 290°C and polyamideimide may have a melting point of about 300°C.

FIG. 2 shows a schematic cross-sectional view when the inner plate 40 is arranged and the composite laminated plate 100 as the outer plate is hemmed. FIG. 3 shows a schematic cross-sectional view of the hemmed composite laminate 100 shown in FIG. As shown in FIG. 2, since springback occurs after hemming, the bending angle of the crimped joint of the composite laminate increases, and the adhesion between the outer plate and the inner plate decreases. According to the composite laminate of the present disclosure, by performing heat treatment and cooling after hemming, as shown in FIG. 3, since the bending angle of the crimped joint is closed, a crimped joint with high adhesion can be obtained. .

Without wishing to be bound by theory, the reason for the closed bend angle is believed to be as follows. During the heat treatment process of the crimped joint or hat-shaped structure obtained from the composite laminate of the present disclosure, thermal strain occurs due to the difference in linear expansion coefficient between the metal layer and the resin layer. Here, if heat treatment is performed at a temperature above (melting point of -20°C) of the adhesive, the adhesive softens or melts. A gap occurs between the layers, and thermal strain due to the difference in linear expansion between the metal layer and the resin layer is alleviated. After the heat treatment, hardening or re-adhesion occurs between the metal layer and the resin layer during the cooling process to less than 100° C., the metal layer and the resin layer shrink, and the difference in linear expansion coefficient causes the metal layer and the resin layer to separate. It is thought that shear stress is generated between and deforms in the direction of closing the bending angle.

If the temperature is less than 100° C., the gap between the metal layer and the resin layer is fixed, and the adhesive softens or melts during the heat treatment, and the gap between the metal layer and the resin layer needs to be displaced.

The metal layer is composed of a metal plate or alloy plate having a melting point above 225° C., preferably a steel plate, an aluminum alloy plate, a copper alloy plate, a pure titanium plate, a titanium alloy plate, or a magnesium alloy plate. The steel sheet preferably has a tensile strength of 270 to 590 MPa and can be, for example, galvanized steel, electroplated steel, tinplate or can steel (TFS: tin-free steel).

The thickness of one adhesive layer is preferably 0.001 to 0.200 mm, more preferably 0.050 to 0.100 mm, still more preferably 0.100 to 0.050 mm. When the adhesive layer has a thickness within the above range, the resin layer and the metal layer can be adhered well.

When the outer plate is hemmed to form a crimped joint with the inner plate, the adhesion between the inner plate and the outer plate at the bent portion (flange portion) of the outer plate is important.

After the skin is hemmed, it may be coated with a sealer to ensure adhesion. Crimp joints are formed by hemming processes such as press bending and roller hemming, which can cause springback and reduce adhesion. According to the composite laminate of the present disclosure, it is possible to improve the adhesion of the crimped joint formed by hemming.

After hemming or pressing, the composite laminate of the present disclosure can have a lower bending angle than before the heat treatment when it is returned to room temperature through heat treatment and cooling treatment. The reduction angle (closed angle) of the bend angle with respect to the bend angle before heat treatment is preferably 0.55° or more, more preferably 2.00° or more, still more preferably 2.30° or more, and even more preferably 2.50°. ° or more, still more preferably 2.60° or more, still more preferably 5.00° or more, still more preferably 5.10° or more. Although the upper limit of the bending angle reduction angle is not particularly limited, it can be, for example, 20° or 10°.

The larger the ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer, the greater the closing angle (variation) of the bending angle in the cooling process after heat treatment, resulting in excellent adhesion. Joints can be obtained, or negative angle structures can be easily obtained.

The ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more, preferably 5 or more, more preferably 7 or more. When forming a crimped joint, the larger the ratio ηp/ηf, the greater the closing angle (variation) of the bending angle in the cooling process after the heat treatment, making it possible to obtain a crimped joint with excellent adhesion. Within the above range, an industrially necessary crimping force can be obtained. When molding a negative angle structure, the larger the ratio ηp/ηf, the greater the closing angle (variation) of the bending angle during the cooling process after heat treatment, and no complicated processes or special molds are required. Moreover, a negative-angle structure having a smaller bending angle can be easily obtained. Negative-angle structures with smaller bend angles are more efficient in obtaining the moment of inertia of area and are more rigid. Although the upper limit of ηp/ηf is not particularly limited, ηp/ηf may be 20 or less, for example.

When ηp/ηf is 3 in the case of 90° bending, the closing angle (variation) of the bending angle becomes 0.55° by heat treatment and cooling treatment. In a part where the sum of ridge line opening angles is 180° or more, the sum of closing angles is 1.1°. In general, when forming a crimped joint between an inner plate and an outer plate by hemming, the required flange length is 25 mm and the surface accuracy is ±0.5 mm. That is, if the surface accuracy is low, a gap of 0.5 mm may occur, resulting in poor bonding. By setting ηp/ηf to 3 or more, the gap at the flange end can be narrowed by 0.5 mm (25 mm×sin (1.1°)=0.5 mm) to close the gap.

For example, the linear expansion coefficient of polyamide 6 (PA6), which is preferable as a material for the resin layer, is 5.9 to 10×10 ⁻⁵ /° C., and the linear expansion coefficient of acetylcellulose is 8 to 18×10 ⁻⁵ /° C. , the linear expansion coefficient of polybutylene terephthalate is 6.0 to 9.5×10 ⁻⁵ /° C., and the linear expansion coefficient of polyamide 66 (PA66) is 8 to 10×10 ⁻⁵ /° C. , the linear expansion coefficient of polyethylene terephthalate is 6.5×10 ⁻⁵ /° C., the linear expansion coefficient of polyphenylene sulfide is 4.9×10 ⁻⁵ /° C., and the linear expansion coefficient of polyamideimide is 3.1×10 ⁻⁵ /°C. For example, the coefficient of linear expansion of a steel plate preferable as a material for the metal layer is 9.0 to 12.8×10 ⁻⁶ /° C., the coefficient of linear expansion of an aluminum plate is 23×10 ⁻⁶ /° C., and the copper plate has a linear expansion coefficient of 17.7×10 ⁻⁶ /°C. Materials for the metal layer and the resin layer can be selected so that ηp/ηf has a desired ratio.

Composite laminates can be produced by sandwiching a resin between metal plates with an adhesive interposed therebetween and performing hot compression bonding. Hot compression bonding is performed, for example, by heating to 100 to 200° C. and pressing at a pressure of 0.01 to 5.00 MPa for 1.0×10 ¹ to 1.0×10 ⁵ seconds.

According to the composite laminate of the present disclosure, heat treatment and cooling can be performed after bending by press working to close the bending angle, so negative angle forming can be easily performed. Negative forming refers to forming a forming having a bend angle of less than 90°. A negative angle structure cannot be formed by a normal press method. Molding a negative angle structure requires multiple processes and a cam method that moves the mold obliquely, which increases the cost.

A negative angle structure obtained by using the composite laminate of the present disclosure can achieve both excellent geometrical moment of inertia, occupied area (volume), and cross-sectional efficiency of member rigidity.

Fig. 4 shows a hat-shaped steel (A) produced by a conventional method using a metal plate, and a hat-shaped steel having the same cross-sectional shape as the hat-shaped steel (A) produced by a conventional method using the composite laminate of the present disclosure. Next, a negative angle structure (B) produced by heat treatment and cooling treatment, and a hat-shaped steel produced by a conventional method in which the flange portion has the same width as the negative angle structure (B) using a metal plate Fig. 3(C) shows a comparison of cross-sectional efficiency of cross-sectional shape, geometrical moment of inertia, occupied area (volume), and member stiffness.

Regarding the geometric moment of inertia, the hat-shaped steel (A), which has the largest cross-sectional area, is superior, but the negative angle structure (B) is also good because of its long line length (distance from the center of the diagram). Steel (C) is inferior due to its small cross-sectional area.

Regarding the occupied area (volume), the hat-shaped steel (A) having the largest cross-sectional area is inferior, and the negative angle structure (B) and the hat-shaped steel (C) are superior.

Hat-shaped steel (A) and hat-shaped steel (C) are insufficient in cross-sectional efficiency of member rigidity, but negative angle structure (B) is excellent.

(Example 1)
Thermocompression-type modified polypropylene with a melting point of 160°C is used as an adhesive between two can steel sheets (TFS) each having a thickness of 0.2 mm and a linear expansion coefficient ηf of 11.7 × 10 ^-6 /°C. A polyamide 6 (PA6) having a plate thickness of 0.54 mm, a melting point of 225 ° C., and a linear expansion coefficient ηp of 8 × 10 ^-5 / ° C. A 5-layer composite laminate having a thickness of 1.1 mm was produced by hot pressing for ⁵ seconds. The length and width dimensions of the composite laminate after crimping were 400 mm×600 mm. The ratio ηp/ηf of the coefficient of linear expansion ηp of the polyamide 6 to the coefficient of linear expansion ηf of the steel sheet for cans was 6.8. The ratio of the total thickness of the resin layers to the total thickness of the metal layers was 1.35.

The bending stiffness of the produced composite laminate was evaluated according to the method shown in FIG. In FIG. 5, a composite laminate 100 with dimensions of 1.1 mm × 30 mm × 200 mm is placed on supporting points of R 5.0 mm arranged at intervals of 100 mm, and the central part is pushed in with a punch of R 5.0 mm and bent. Represents a method for measuring bending stiffness when molded. The bending rigidity was similarly evaluated for the aluminum plate and the steel plate for cans (TFS).

As shown in FIG. 22 , the composite laminate prepared in Example 1 has a mass equivalent to that of a 0.50 mm thick steel sheet for cans (TFS), but the bending rigidity is significantly higher than that of a 0.50 mm thick steel sheet for cans. Bending stiffness was obtained. This flexural rigidity was equivalent to that of an aluminum plate with a thickness of 1.3 mm. Thus, the composite laminate produced in Example 1 exhibited light weight and high flexural rigidity.

(Example 2)
Two tin plates each having a plate thickness of 0.2 mm and a coefficient of linear expansion ηf of 11.7×10 ⁻⁶ /° C. are sandwiched between two tin plate plates with a thermocompression type modified polypropylene having a melting point of 160° C. as an adhesive. Polyamide 6 (PA6) having a plate thickness of 54 mm, a melting point of 225° C. and a linear expansion coefficient ηf of 8×10 ⁻⁵ /° C. was sandwiched and hot-pressed at 180° C. and 10,000 kg for 1.0×10 ⁵ seconds. Thus, a five-layer composite laminate having a thickness of 1.1 mm was produced. The length and width dimensions of the composite laminate after crimping were 400 mm×600 mm. The ratio ηp/ηf of the linear expansion coefficient ηp of polyamide 6 to the linear expansion coefficient ηf of the tin plate was 6.8.

Without the inner plate, hemming with an inner R bending radius of 1.0 mm was performed by press bending shown in FIG. 9 to obtain the hemmed composite laminate shown in FIG. As shown in FIG. 9, in press bending, 180 degree bending was completed in two steps. Next, it was placed in a drying oven, heated to 170° C. at 0.1° C./sec in the atmosphere, subjected to heat treatment at 170° C. for 20 minutes, and then air-cooled to room temperature. By performing the heat treatment and cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemmed portion was closed.

(Example 3)
A composite laminate was produced under the same conditions as in Example 2, except that hemming was performed using the roller hem shown in FIG. A laminated composite laminate was obtained. As shown in FIG. 10, for roller hemming, a 180 degree bend was completed in all four steps. Then, heat treatment and cooling treatment were performed in the same manner as in Example 2.

FIG. 11 shows a side view photograph of the composite laminate of Example 3 after heat treatment at 170° C. for 20 minutes and cooling to room temperature. By performing the heat treatment and cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemmed portion was closed.

(Example 4)
A composite laminate was produced under the same conditions as in Example 3 except that heat treatment was performed at 170 ° C. for 5 minutes and then air cooling to room temperature, hemming was performed, heat treatment and cooling were performed, and the hemming shown in FIG. 13 was performed. A processed composite laminate was obtained. By performing the heat treatment and cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemmed portion was closed.

(Example 5)
After heating to 140° C., a composite laminate was produced under the same conditions as in Example 3, except that the temperature was not maintained and air-cooled to room temperature, hemming, heat treatment and cooling were performed. The hemmed composite laminate shown was obtained. By performing the heat treatment and cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemmed portion was closed.

(Example 6)
A composite laminate was produced under the same conditions as in Example 2 except that a thermocompression modified polypropylene with a melting point of 170 ° C. was used as the adhesive, and hemming was performed with an inner R bending radius of 1.0 mm. A laminate was obtained. Then, heat treatment and cooling treatment were performed under the same conditions as in Example 2.

(Comparative example 1)
A tin plate having a thickness of 0.2 mm was hemmed under the same conditions as in Example 2 to obtain a hemmed metal plate shown in FIG.

Table 1 shows the angle (variation) at which the bending angle of the composite laminates of Examples 2 to 6 and the metal plate of Comparative Example 1 closed after the heat treatment and cooling treatment, with reference to before the heat treatment.

The bending angle of the steel plate of Comparative Example 1 was almost constant before and after the heat treatment and cooling treatment, but the composite laminates of Examples 2 to 6 had a higher bending angle due to the heat treatment and cooling treatment than before the heat treatment. significantly smaller.

(simulation analysis)
The bending angle changes in the closing direction during heat treatment and room temperature cooling, assuming that the adhesive melts during the heat treatment and re-adhesion occurs between the metal layer and the resin layer during the cooling process. I did the analysis.

FIG. 14 shows the analysis model. A 20 mm long composite laminated plate in which a 0.7 mm thick resin layer is sandwiched between 0.2 mm thick (total thickness of 0.4 mm) steel plate layers is connected at a corner with a bending angle of 90° and an inner bending radius R of 1 mm. I created a model. In the model created, the adhesive does not melt and keeps the steel and resin layers bonded, and the steel and resin layers have a common contact point. For this model, the heat shrinkage strain during cooling from 180°C to 25°C was calculated. Table 2 shows the physical property values of the steel plate layer and the resin layer.

15 and 16 show simulation results. As shown in Figure 15, cooling from 180°C to 25°C reduced the bend angle by 1.6°. From the results of FIG. 16, it can be seen that the bend angle decreases almost linearly upon cooling.

We further analyzed the decrease of the bending angle during the cooling process by dividing into the inside and outside of the bend. FIG. 17 shows an analysis model for the inside of the bend, and FIG. 18 shows an analysis model for the outside of the bend.

Figures 17 and 18 show that composite laminates with a length of 4 mm, in which a resin layer of 0.7 mm thickness is sandwiched between steel layers of 0.2 mm thickness, are connected at a corner with a bending angle of 90° and an inner bending radius R of 1 mm. This is a model in which the object is cut parallel to the joining surface of the steel plate layer and the resin layer at the center position in the thickness direction of the resin layer. That is, in each of FIGS. 17 and 18, the thickness of the resin layer is 0.35 mm.

FIG. 19 shows the result of thermal shrinkage analysis of the model of FIG. FIG. 20 shows the result of thermal shrinkage analysis of the model of FIG. From the contour diagrams showing the amount of displacement in FIGS. 19 and 20, it can be seen that the bending angle on the inner side of the bend increases with the cooling treatment, and the bending angle on the outer side of the bending decreases with the cooling treatment.

From the analysis results of FIGS. 19 and 20, when the steel plate is placed outside the bend, the maximum shear stress is 217 MPa, and when the steel plate is placed inside the bend, the maximum shear stress is 161 MPa. rice field.

From the above results, it can be seen that the amount of displacement in the corner closing direction and the shear stress between layers are larger when the steel plate is placed outside the bend than when the steel plate is placed inside the bend. Placing the steel plate outside the bend has a larger interfacial area between the steel plate layer and the resin layer than placing the steel plate inside the bend. The larger the boundary area, the greater the shear stress, which governs the bending direction of the bending angle.

With the linear expansion coefficient ηf of the steel plate layer fixed at 11.7×10 ⁻⁶ (/° C.), the linear expansion coefficient ηp of the resin layer was changed as shown in Table 3 and FIG. By changing ηp/ηf in the range of 1 to 11, the closing angle of R in bending with respect to the linear expansion coefficient ratio ηp/ηf was investigated.

The larger the ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer, the greater the closing angle (variation) of the bending angle in the cooling process after heat treatment, resulting in excellent adhesion. A joint can be obtained, and a negative angle molded article can be easily obtained. When ηp/ηf is 3 or more, the closing angle (variation) of the bending angle due to heat treatment and cooling treatment is 0.55° or more.

REFERENCE SIGNS LIST 100 composite laminate 10 metal layer 20 resin layer 30 adhesive layer 40 inner plate

Claims (4)

Including a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100° C. or higher and 170° C. or lower,
The adhesive layer is composed of an adhesive, the adhesive is a thermocompression-type modified polypropylene adhesive,
The resin layer has a melting point higher than the melting point of the adhesive layer,
The resin of the resin layer is at least one of polyamide 6, acetylcellulose, polybutylene terephthalate, polyamide 66, polyethylene terephthalate, polyphenylene sulfide, and polyamideimide;
A ratio ηp/ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The total plate thickness is 0.8 mm or more,
Composite laminate. A ratio of the total thickness of the resin layers to the total thickness of the metal layers is greater than 1.00,
The composite laminate of Claim 1. Having a five-layer structure of metal layer / adhesive layer / resin layer / adhesive layer / metal layer,
A composite laminate according to claim 1 or 2. further comprising a reticulated wire layer;
Having a seven-layer structure of metal layer / adhesive layer / mesh wire layer / resin layer / mesh wire layer / adhesive layer / metal layer,
The composite laminate according to any one of claims 1-3.

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