JPS6116618B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a post-processable heat-resistant laminate consisting of 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. be. 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 with a polyimide resin layer of the same type. 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 resides in a method for producing a post-processable heat-resistant laminate, which comprises laminating an aluminum plate whose surface has been subjected to chromate treatment and a solvent-soluble 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 an imide group in its main chain and is soluble in organic solvents, and is preferably amorphous. 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, aromatic dicarboxylic acid or tricarboxylic acid anhydride may be incorporated as a copolymerization component, or a polymer consisting of aromatic dicarboxylic acid and aromatic, aliphatic or alicyclic diisocyanate may be blended into the polyimide condensate. This increases the effect even further. Aromatic diisocyanate compounds include toluylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, diphenyl ether diisocyanate, m-
Xylene diisocyanate etc. can be used,
As the aliphatic diisocyanate compound, hexamethylene diisocyanate, ethylene diisocyanate, etc. can be used, and as the alicyclic diisocyanate, cyclohexane diisocyanate, etc. can be used, but aromatic diisocyanates are preferable 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 each is copolymerized. good. In order to satisfy the purpose of the present invention, the intrinsic viscosity of the polyimide resin to be used is 0.25 dl/
g or more and 3.0 dl/g or less is desirable. Intrinsic viscosity
If it is smaller than 0.25, the resulting resin layer will be hard and brittle, and the resin will crack or break during folding, drawing, etc. If the intrinsic viscosity is greater than 3.0, the degree of polymerization will be too high, causing difficulties in laminating (coating) with aluminum plates. 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. Examples of organic solvents that can be used here include N-methyl-2-pyrrolidone, N·N'-dimethylformamide, N·N'-dimethylacetamide, or hydrocarbonic 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. When the polyimide resin of the present invention is used in combination with a polyamideimide resin, the adhesive strength with the aluminum plate is further improved. A polyamide-imide resin is a resin having an imide bond and an amide bond in its molecular chain, and is described, for example, in JP-A No. 56-53149. It is usually obtained by reacting an aromatic carboxylic acid having both an acid anhydride group and a carboxyl group, such as trimellitic anhydride, with a diisocyanate compound similar to that used in producing polyimide resins. Further, it is preferable to use an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid as the carboxylic acid component. The polyamide-imide resin is preferably used in an amount of 2 to 200% by weight, preferably 2 to 100% by weight, based on the polyimide resin. If too much polyamide-imide resin is used, heat resistance tends to decrease. 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.
It was confirmed that an aluminum plate with a chromate treatment film can withstand post-processing such as bending and drawing. There are two types of chromate treatment solutions: alkaline and acidic. Alkaline types include Na ₂ CO ₃ /Na ₂ CrO ₄ (MBV method),
Examples include Na ₂ CO ₃ /Na ₂ CrO ₄ /NaHPO ₄ system (LW method). Also, as an acidic type, H ₃ PO ₄ /NaF/
CrO ₃ -based Alodine method, Cr ₂ O ₃ /
Na ₂ Cr ₂ O ₇ /NaF system (chromate method), ZnHPO ₄ /
H ₃ PO ₄ /CrO _3- based bonderite (Bonderite method),
There are Na ₂ Cr ₂ O ₇ /H ₂ SO ₄ systems, etc. In the present invention, acidic type chromates are particularly effective, and in addition to the above-mentioned H ₃ PO ₄ and H ₂ SO ₄ , HCl,
HNO ₃ etc. are also effective. The concentration of the chromate treatment solution, treatment time, etc. may be carried out under known treatment conditions. For example, in the MBV method
The treatment conditions include 2 to 5% Na ₂ CO ₃ and 0.5 to 2.5% Na ₂ CrO ₄ at 90 to 100° C. for 3 to 5 minutes. In addition, in the Alodine method _{, PO 3-4} ^is 20 to 100 g/,
F ^- is 2 to 6 g/CrO ₃ is 6 to 20 g/, and the treatment conditions are 20 to 50° C. for 2 to 5 minutes. In addition, in the Na ₂ Cr ₂ O ₇ /H ₂ SO ₄ system, Na ₂ Cr ₂ O ₇ is 1 to 4%, H ₂ SO ₄ is 6 to 40%, and the treatment conditions are 20
It may be treated at ~80°C for 2 to 10 minutes. 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 already explained, chemical reactions do not proceed, and mere surface roughening treatment does not cause deformation such as local elongation or shrinkage of the aluminum layer during folding or drawing. The adhesive force is still insufficient. In chromate treatment to create surface irregularities or active chemical films, it is thought to be effective for deformation such as local expansion and contraction. In addition,
The aluminum plate used here refers to a pure aluminum plate or an alloy plate whose main component is aluminum, such as silicon, magnesium, iron,
It is an aluminum alloy plate containing 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 laminate of the present invention thus obtained 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 advantageous 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% of 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. Resin Production Example 2 A resin was produced according to the production method disclosed in JP-A No. 56-53149. i.e. in 10 pre-dried reactors.
614.82 g (3.20 moles) of trimellitic anhydride and 132.90 g (0.80 moles) of isophthalic acid were charged. The reactor was equipped with a thermometer, condenser, stirrer, and nitrogen inlet. 1000.96g (4.0mol) in a dry bottle of 3
4,4'-methylenebis(phenyl isocyanate) (MDI), then 434 ml of N-methylpyrrolidone (NMP),
was dissolved. This MDI solution was added to the reactor and then used to rinse the bottle from which the MDI was weighed.
Added 3650ml of NMP. The solution was heated from 53°C for 3 hours 40 minutes at a stirring rate of 65 rpm and under a nitrogen atmosphere.
Heat to 170℃, then 169℃ for another 1 hour and 55 minutes.
It was heated to 171°C. In this way, about 80% of the repeating units are structured approximately 20% of the repeating units are structural In NMP of random copolyamideimide with
A 25% by weight solution was obtained. This copolyamideimide had an intrinsic viscosity of 0.603 at 30°C. The reactant was poured into water to precipitate a polymer, which was then taken out and thoroughly dried. Dissolve the dried polymer in dimethylformamide and add 20wt
Adjusted to % varnish. Example 1 An aluminum plate with a purity of 99.5% and a thickness of 0.8 mm,
After degreasing, Na ₂ Cr ₂ O ₇・2H ₂ O:
It was immersed in a chromate bath containing H ₂ SO ₄ :H ₂ O in a ratio of 1:10:30 (weight ratio). Processing conditions are 60℃
It lasted 7.5 minutes. Then, it was washed with water and dried. Example 1 of resin production on this chromate-treated aluminum plate
Polymer varnish (21wt% dimethylformamide solution) was coated and dried until the amount of residual DMF (dimethylformamide) was 700 ppm or less to produce an aluminum-polyimide laminate. The resin layer thickness was 15μ. The obtained laminate was tested for foldability and drawability. Folding workability was determined by pressing until the folded portion was completely adhered, and observing for cracks in the folded portion and peeling between the resin layer and the aluminum layer. In addition, regarding drawing processability,
Deep drawing testing machine, TF-102-12 type (manufactured by Tokyo Koki Co., Ltd.)
As a test piece from the laminate using 5.5
After cutting a square plate of cm x 5.5 cm and narrowing the center to a depth of 7 mm as shown in Figure 1, the adhesion with the aluminum plate at resin coated surfaces A, B, and C areas (regions) was confirmed. I observed about. 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. Example 2 In Example 1, instead of the polymer varnish of Resin Production Example 1, a polyimide resin containing polyamide-imide blended at a ratio of 75% of the polymer varnish of Resin Production Example 1 and 25% of the polymer varnish of Resin Production Example 2 was used. The test was carried out in the same manner as in Example 1 except that it was coated with varnish. The results are shown in Table-2. Examples 3 to 5 Same as Example 2 except that the ratio of Na ₃ Cr ₂ O ₇・2H ₂ O:H ₂ SO ₄ :H ₂ O and the blend ratio of the resins of Resin Production Examples 1 and 2 were changed. The same was tested. Processing conditions are 60℃ for 7.5 minutes.

[Table] The results are shown in Table-2. Example 6 Chromate bath ZnHPO ₄ :H ₃ PO ₄ :CrO ₃ :H ₂ O
=28:25:10:937, resin production examples 1 and 2
The test was conducted in the same manner as in Example 2, except that the blend ratio of the resins was changed to 50:50. The results are shown in Table-2. Comparative Examples 1 to 3 Laminates were manufactured in exactly the same manner as in Example 1, except that the surface treatment of the aluminum plate was changed from the chromate treatment to the treatment shown in Table 1. The drawing processability was also evaluated. Table 1 shows the surface treatment conditions, and Table 2 shows the results of workability studies.

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【table】 [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. A method for producing a heat-resistant laminate that can be post-processed, comprising laminating an aluminum plate whose surface has been subjected to chromate treatment and a solvent-soluble polyimide resin. 2. The manufacturing method according to claim 1, characterized in that a resin in which 2 to 200% by weight of polyamide-imide resin is mixed with polyimide resin is laminated.