JPS6344059B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a post-processable heat-resistant laminate comprising a layer made of a solvent-soluble polyimide resin and an aluminum layer. As is well known, polyimide resins containing imide groups in their main chains are insoluble in solvents.
Therefore, in the case of manufacturing a laminate that satisfies the spirit of the present invention, the polyimide precursor with ring-opened imide groups, that is, polyamic acid, is soluble in organic solvents. Coating the aluminum layer with an acid solution, evaporating the solvent, and proceeding with the imide ring closure reaction,
A polyimide layer is formed, and at this time water is generated due to the progress of the imide ring closure reaction and foaming occurs. In order to prevent foaming, the ring closure reaction time must be increased. A laminate with an aluminum plate manufactured using such a polyimide resin is heat resistant and can be a useful material in the manufacturing industry, but various problems occur when post-processing is performed as described below. . That is, when manufacturing, for example, a printed wiring board using such a laminate of polyimide resin and aluminum plate, the resin layer may crack or break when performing post-processing such as folding or drawing. It is. Furthermore, as mentioned above, such polyimide resin is imidized by imide ring closure reaction via polyamic acid, and therefore is a type of crosslinked polymer and therefore cannot be heat-sealed. That is, it is impossible to heat seal the polyimide resin layer of such a laminate and the same polyimide resin layer. The present inventors have overcome these problems and achieved heat resistance,
The present invention was arrived at as a result of extensive research into obtaining a laminate that has excellent insulation properties and can be subjected to post-processing such as folding, drawing, or heat-sealing. That is, the gist of the present invention is an aluminum plate whose surface is anodized, and the anodized surface has pores having an average diameter of 350 to 800 Å and a density of at least 50 pores/μ ² and a solvent-soluble aluminum plate. It consists in a heat-resistant laminate which can be post-processed and is made by laminating polyimide resin. Hereinafter, to explain the present invention in more detail, the solvent-soluble polyimide resin used in the present invention is:
It should be a thermoplastic resin that contains imide groups in its main chain and is soluble in organic solvents, preferably amorphous, and may be a copolymer with amide groups, etc. . Such polyimide resin can be manufactured by a well-known method. That is, it can be obtained by a polycondensation reaction of an aromatic tetrabasic acid anhydride and an aromatic, aliphatic or alicyclic diisocyanate. At this time, an aromatic dicarboxylic acid can be incorporated as a copolymerization component, or a polymer consisting of an aromatic dicarboxylic acid and an aromatic, aliphatic or alicyclic diisocyanate can be blended into the polyimide condensate. Aromatic diisocyanate compounds include toluylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate,
Diphenyl ether diisocyanate, m-xylene diisocyanate, etc. can be used, hexamethylene diisocyanate, ethylene diisocyanate, etc. can be used as the aliphatic diisocyanate compound, and cyclohexane diisocyanate, etc. can be used as the alicyclic diisocyanate. Aromatic diisocyanates are desirable from the viewpoint of heat resistance, which is a feature of the present invention. On the other hand, aromatic tetrabasic acid anhydrides include 3,3′,
4,4'-benzophenonetetracarboxylic anhydride, pyromellitic anhydride, 3,3',4,4'-biphenyltetracarboxylic anhydride, etc. can be used, but even if they are copolymerized, good. In order to satisfy the purpose of the present invention, the intrinsic viscosity of the polyimide resin to be used must be 0.25 as measured at 30°C in N,N'-dimethylformamide solution.
Desirably dl/g or more and 3.0 dl/g or less. If the intrinsic viscosity is less than 0.25, the resulting resin layer will be hard and brittle, and the resin layer will crack or break during folding, drawing, etc. Intrinsic viscosity
If it is larger than 3.0, the degree of polymerization will be too high, causing difficulties in laminating (coating) with an aluminum plate. The viscosity is adjusted by appropriately adding an organic solvent that does not cause precipitation to the polycondensation solution obtained in this way, and it is coated on an aluminum plate or aluminum foil to quickly volatilize the solvent, but at this time the chemical reaction does not occur. Since no water is generated, it does not cause foaming. Here, examples of organic solvents that can be used include N-methyl-2-pyrrolidone, N,N'-dimethylformamide, N,N'-dimethylacetamide, and carbolic acid derivatives, which may be used alone or in combination. It is also possible to mix easily volatile solvents such as benzene and toluene within a range that does not cause precipitation. Coating the polyimide resin solution onto the aluminum layer is carried out using a known method. In order to achieve the present invention, it is further important to prevent the resin layer and aluminum layer from peeling off during post-processing such as folding and drawing. The present inventors have found that surface treatment of the aluminum plate is essential to overcome this problem. In general, surface treatments for improving the adhesion of aluminum plates include chemical conversion film formation methods such as chromate treatment, phosphate treatment, titanium tannate treatment, sulfuric acid, phosphoric acid, chromic acid, sulfamic acid, etc.
A method of forming an anodic oxide film using an electrolytic bath containing boric acid, oxalic acid, sulfosalicylic acid, malonic acid, succinic acid, citric acid, malic acid, etc., electrolytic surface roughening treatment using an electrolytic bath such as hydrochloric acid, nitric acid, or brush polishing. There are methods such as mechanical roughening treatment such as honing, but the present inventors used the method described above for bonding polyimide resin and aluminum plate.
The average diameter is 350-800 Å and the density is at least 50 Å/
It was confirmed that an aluminum plate with an anodized film having micropores of μ ² can completely withstand post-processing such as bending and drawing. When using a conventionally known polyimide resin made by imide ring closure of polyamic acid, cracks occur in the resin layer during the folding and drawing processes, but the adhesion to aluminum is good and the surface No processing required. This means that in the process of polyamic acid causing an imide ring-closing reaction and polyimidation, not only intramolecular ring-closing but also intermolecular reactions occur, which chemically reacts with aluminum at the interface with the aluminum layer, resulting in not only strong adhesion. It is presumed that the physicochemical adhesive force with aluminum due to the generated functional groups, together with the strength of the physicochemical adhesion with aluminum, provides strong adhesion even against large deformations such as drawing. When using the resin based on the present invention, as described above, chemical reactions do not proceed, and since it does not have functional groups that can physicochemically adhere to the aluminum layer such as hydrogen bonds, chemical conversion treatment or surface roughening is required. Although the adhesion strength improves to a certain degree with processing, the adhesive strength is still insufficient when the aluminum layer is deformed by local elongation or shrinkage, such as during folding or drawing, and oxidation generated during anodization, etc. It is thought to be effective in surface treatment in which a large number of fine pores are provided in the film layer, and in the case of deformation such as local expansion and contraction. In carrying out the present invention, the average diameter is 350 to 800 Å.
For example, an anodic oxide film having pores with a density of at least 50 pores/ ^μ2 can be obtained by coating an aluminum plate with phosphoric acid.
In 10-50% aqueous solution, temperature 10-50℃, voltage 10
Obtained by anodizing with ~50V DC or AC. The electrolysis time varies depending on the desired thickness of the oxide film, but is generally 1 to 30 minutes.
Note that the aluminum plate used here refers to a pure aluminum plate or an alloy plate whose main component is aluminum, such as silicon, magnesium,
It is an aluminum alloy plate containing iron, copper, zinc, manganese, chromium, titanium, etc., and although there is no particular specification for the thickness of the plate, it is generally about 0.03 to 3.0 mm. The thus obtained laminate of the present invention not only has excellent heat resistance, insulation, and chemical resistance, but also has post-processing performance of the laminate such as folding, drawing, or heat sealing. It can be an extremely useful material in industry. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Resin Preparation Example 1 Using the procedure described in Example 4 of U.S. Pat. and 20 mol% 4,
A copolyimide was polymerized from a mixture containing 4'-diphenylmethane diisocyanate. Dimethylformamide was used as the polymerization solvent, and the resin concentration was 21 wt%. The intrinsic viscosity was 0.6 dl/g and the viscosity of the solution was 280 poise. Example 1 An aluminum plate with a purity of 99.7% and a thickness of 0.6 mm,
30% in 30% phosphoric acid aqueous solution after degreasing
It was anodized at 40V (DC) for 3 minutes at ℃, washed with water, and dried. As a result of electron microscopic observation, the pore size of the obtained anodic oxide film was 500 to 800.
The average thickness was about 650 Å, and the density was about 100 cells/μ ² . This anodized aluminum plate is coated with polyimide resin polymerized by the method of resin production example 1, and residual DMF (dimethylformamide) is removed.
The aluminum-polyimide laminate was produced by drying until the amount was 700 ppm or less. The resin layer thickness was 15μ. The obtained laminate was tested for foldability and drawability. In the folding method, the folded parts were pressed until they were completely in contact with each other, and cracks in the folded parts and peeling between the resin layer and the aluminum layer were observed. Regarding the drawing method, a deep drawing tester TF-102-12 model (manufactured by Tokyo Koki Co., Ltd.) was used to draw a 5.5 cm x 5.5 cm test piece from the laminate.
After cutting a square plate and narrowing the center to a depth of 7 mm as shown in Figure 1, resin coated surfaces A, B,
And the adhesion with the aluminum plate in the C part (area) was observed. The evaluation criteria for folding workability and drawing workability are as follows. ◎: Complete adhesion and no abnormality. △: Approximately halfway between ◎ and × (some cracks and peeling are observed) ×: Cracks and peeling clearly occur. The results are shown in Table 2. Comparative Examples 1 to 6 Laminated bodies were produced in exactly the same manner as in Example 1, except that the surface treatment of the aluminum plate was changed from phosphoric acid anodization treatment to the treatment shown in Table 1. Curling workability and drawing workability were also evaluated. Table 1 shows the surface treatment conditions, and Table 2 shows the processability results.

【table】

[Table] Example 2 Using the resin solution produced in Resin Production Example 1, a polyimide film having a film thickness of 26 μm was obtained by casting according to a known method. The content of N,N'-dimethylformamide contained in this film is
It was below 700ppm. The above polyimide film was applied to the resin layer of the laminate produced by the phosphoric acid anodizing method used in Example 1.
Heat and pressure bonding was carried out at 350℃. The condition of the crimped part is good, and the peel strength between the film layer and the laminate is 3.4.
It was Kg/cm. Separately, two sheets of this laminate were heat-pressed together at 350° C. to form resin layers. The peel strength of both laminates was 5.2 kg/cm, which was good. Comparative Example 7 KAPTON 100H (thickness 26μ) manufactured by Dupon't is a representative example of polyimide resin that undergoes imide ring-closing reaction.
When the two films were heat-pressed at 350°C to 400°C, no adhesion occurred. In addition,
At temperatures above 400°C, Al became slightly softened and deformed during the crimping process.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an embodiment of a test piece obtained by drawing the laminate of the present invention, in which A and B are 1-1'.
A schematic cross-sectional view taken along the line, and b is a top view.

Claims (1)

[Claims] 1. An aluminum plate whose surface is anodized,
A post-processable heat-resistant laminate comprising an aluminum plate whose anodized surface has pores having an average diameter of 350 to 800 Å and a density of at least 50 pores/μ ² and a solvent-soluble polyimide resin. 2 Anodizing at a phosphoric acid concentration of 10-50% and a temperature of 10-50%
The heat-resistant laminate according to claim 1, which uses an aluminum plate subjected to the electrolysis at a temperature of 10 to 50 V. 3 Claim 1: A polyimide resin soluble in an organic solvent obtained by a decarboxylation polycondensation reaction of an aromatic tetrabasic acid anhydride and an aromatic, aliphatic or alicyclic diisocyanate. The heat-resistant laminate described.