JP2018024262A - Laminate and manufacturing method of laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible laminate having practical heat resistance and high dimensional stability and containing a porous layer, which is used as a heat insulation sheet for protecting electronic components which are weak to heating in a thin televisions, mobile devices, laptop computers or the like.SOLUTION: There is provided a laminate with 2 or more layers including at least one porous layer, having a thermal conductance in a thickness direction of the laminate of 1000 W/m2 or less and a liner expansion coefficient in a direction orthogonal to the thickness direction at 200°C or less of ±100 ppm/K% or less.SELECTED DRAWING: None

Description

  The present invention relates to a laminate including a porous layer having heat resistance and high dimensional stability. The laminate including the porous layer is used as a heat insulating sheet that protects electronic components that are vulnerable to heating in thin televisions, mobile devices, laptop computers, and the like. Moreover, it can be used as a wide range of basic materials such as low dielectric constant circuit boards, high frequency circuit boards, electromagnetic wave control materials such as electromagnetic wave shields and electromagnetic wave absorbers, etc. by utilizing the holes. It can also be used to protect automotive electronic devices from heat.

  In recent years, with the improvement of CPU performance and circuit board integration, the importance of heat management inside electronic devices due to the heat generated from these electronic components is increasing. In many cases, a small fan is provided in order to release the heat generated inside these electronic devices to the outside. However, installation of a small fan requires space, and power for its operation is required, so application to mobile devices must be limited.

  Further, a technique for releasing heat to the outside by a member having high thermal conductivity such as a graphite sheet is disclosed. However, the graphite sheet is expensive, and the heat dissipation effect changes depending on the temperature difference with the outside and the efficiency of heat exchange with the contacting medium, so it is difficult to design with the expectation of a role beyond the complementary heat dissipation function. I think that the.

  Moreover, various sponge-like heat insulating materials and film-like heat insulating sheets have been proposed and used in industry (Patent Document 1, Patent Document 2). However, since the heat insulating material manufactured using a foaming agent is thick as it is, the places where it can be used are limited. In addition, there is an example in which a thin film is used by pressing, but it is difficult to use inside an electronic device because it loses flexibility and becomes plate-like and there is a limit to thin film.

  Furthermore, in these insulations, the apparent thermal conductivity is used as a physical property value specific to the material, but since the actual thermal conductivity varies depending on the thickness, it is not always expected from the apparent thermal conductivity. There was a problem of not exhibiting the heat insulation effect as much as possible.

JP 10-259268 A JP 2011-184574 A

  An object of the present invention is to provide a flexible laminate including a porous layer having practical heat resistance and high dimensional stability. Moreover, this laminated body can be utilized as a wide range of basic materials such as a low dielectric constant circuit board, a high frequency circuit board, an electromagnetic wave control material such as an electromagnetic wave shield and an electromagnetic wave absorber, making use of the pores.

The present invention is as follows.
1. It is a laminate of two or more layers including at least one porous layer,
A laminate having a thermal conductance in a thickness direction of the laminate of 1000 W / m ² K or less and a linear expansion coefficient in a direction perpendicular to the thickness direction of 200 ° C. or less of 100 ppm / K or less.

2. The layered product according to item 1, wherein the layer other than the porous layer is a layer selected from non-porous polyimide or polyamide.

3. 2. The laminate according to item 1, wherein the laminate has three or more layers, the porous layer is an inner layer, and the outermost layer is a nonporous film.

4). Item 4. The laminate according to any one of items 1 to 3, wherein the porosity of the entire laminate is 40% or more.

5. Item 5. The laminate according to any one of Items 1 to 4, wherein the porous layer is a polyimide porous layer.

6). The porous layer is
A three-layer polyimide porous layer having two surface layers (a) and (b) and a macrovoid layer sandwiched between the surface layers (a) and (b),
The macrovoid layer has a partition wall bonded to the surface layers (a) and (b), and an average pore diameter in the film plane direction surrounded by the partition wall and the surface layers (a) and (b) is 10 to 500 μm. Having a plurality of macrovoids,
The partition wall of the macrovoid layer has a thickness of 0.1 to 50 μm and has a plurality of pores having an average pore diameter of 0.01 to 50 μm, and each of the surface layers (a) and (b) has a thickness. Is 0.1 to 50 μm, and at least one surface layer has a plurality of pores having an average pore diameter of 0.01 to 200 μm, and the partition walls of the macrovoid layer and the surface layers (a) and (b) The pores communicate with each other and further communicate with the macro void.
Item 6. The laminate according to any one of Items 1 to 5, which is a porous film having a total film thickness of 5 to 500 µm and a porosity of 50 to 95%.

7). The manufacturing method of the laminated body of any one of said claim | item 1-6 including the process of adhere | attaching the polyimide film which has a heat-fusion layer, and a polyimide porous membrane with a hot press.

  An object of the present invention is to provide a flexible laminate including a porous layer having practical heat resistance and high dimensional stability. Moreover, this laminated body can be utilized as a wide range of basic materials such as a low dielectric constant circuit board, a high frequency circuit board, an electromagnetic wave control material such as an electromagnetic wave shield and an electromagnetic wave absorber, making use of the pores. In addition, the laminate including the porous layer is used as a heat insulating sheet for protecting electronic components that are vulnerable to heating in thin televisions, mobile devices, notebook personal computers, and the like. Moreover, it can be used as a wide range of basic materials such as low dielectric constant circuit boards, high frequency circuit boards, electromagnetic wave control materials such as electromagnetic wave shields and electromagnetic wave absorbers, etc. by utilizing the holes. It can also be used to protect automotive electronic devices from heat.

  The laminate of the present invention is a laminate of two or more layers including at least one porous layer.

<Porous layer>
The porous layer used in the present invention is characterized by being porous, and a porous film can be used as the porous layer, and a polyimide porous film or the like is preferably used as the porous film. Although this polyimide porous membrane is not necessarily limited, the following can be used.

  The porous polyimide film of the present invention is a porous polyimide film mainly composed of a polyimide obtained from tetracarboxylic dianhydride and diamine, preferably from a polyimide obtained from tetracarboxylic dianhydride and diamine. A porous polyimide film.

  As the tetracarboxylic dianhydride, any tetracarboxylic dianhydride can be used, and can be appropriately selected according to desired characteristics. Specific examples of tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3 ′, 4 ′. -Biphenyltetracarboxylic dianhydride such as biphenyltetracarboxylic dianhydride (a-BPDA), oxydiphthalic dianhydride, diphenylsulfone-3,4,3 ', 4'-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2, 3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), p-biphenylenebis (trimellitic acid monoester acid anhydride), m-terphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, p-terphenyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, 1,3-bis ( 3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride 2,2-bis [(3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra Carboxylic acid dianhydride, 4,4 '- (2,2-hexafluoroisopropylidene) may be mentioned diphthalic dianhydride and the like. It is also preferable to use an aromatic tetracarboxylic acid such as 2,3,3 ', 4'-diphenylsulfonetetracarboxylic acid. These can be used alone or in combination of two or more.

  Among these, in particular, at least one aromatic tetracarboxylic dianhydride selected from the group consisting of biphenyltetracarboxylic dianhydride and pyromellitic dianhydride is preferable. As the biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride can be suitably used.

  Arbitrary diamine can be used for diamine. Specific examples of diamines include the following.

1) One benzene nucleus such as 1,4-diaminobenzene (paraphenylenediamine), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene,
2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether and 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'- Dimethyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′- Dicarboxy-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, bis (4-aminophenyl) sulfide, 4,4′-diaminobenzanilide, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine, 2,2′-dimethylbenzidine, 3,3′-dimethoxybenzidine 2,2′-dimethoxybenzidine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diamino -4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2, 2-bis (3-aminophenyl) propane, 2,2-bis 4-aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1 , Two benzene nucleus diamines such as 1,3,3,3-hexafluoropropane, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide,
3) 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-amino) Phenyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3 -Aminophenoxy) -4-trifluoromethylbenzene, 3,3'-diamino-4- (4-phenyl) phenoxybenzophenone, 3,3'-diamino-4,4'-di (4-phenylphenoxy) benzophenone, 1,3-bis (3-aminophenyl sulfide) benzene, 1,3-bis (4-aminophenyl sulfide) benzene, 1,4-bis (4-aminophenyls) Fido) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3-bis (4-aminophenylsulfone) benzene, 1,4-bis (4-aminophenylsulfone) benzene, 1,3- Bis [2- (4-aminophenyl) isopropyl] benzene, 1,4-bis [2- (3-aminophenyl) isopropyl] benzene, 1,4-bis [2- (4-aminophenyl) isopropyl] benzene, etc. The benzene core of three diamines,
4) 3,3′-bis (3-aminophenoxy) biphenyl, 3,3′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [3- (3-aminophenoxy) phenyl] ether, bis [3- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, Bis [4- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, bis [3- (4-aminophenoxy) phenyl] ketone, bis [4- (3-amino Phenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [3- (3-aminophenoxy) phenyl] Sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [3- (3 -Aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, Bis [3- (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-amino Phenoxy) phenyl] methane, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, , 2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ] Propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) Phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoro Four diamine diamines such as propane and 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane.

  These may be used alone or in combination of two or more. The diamine to be used can be appropriately selected according to desired characteristics.

  Among these, aromatic diamine compounds are preferable, and 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether and paraphenylenediamine, 1,3-bis (3-aminophenyl) Benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-amino) Phenoxy) benzene and 1,4-bis (3-aminophenoxy) benzene can be preferably used. In particular, at least one diamine selected from the group consisting of benzenediamine, diaminodiphenyl ether and bis (aminophenoxy) phenyl is preferred.

  The porous polyimide film is composed of a tetracarboxylic dianhydride and a diamine having a glass transition temperature of 240 ° C. or higher or a clear transition point of 300 ° C. or higher from the viewpoint of heat resistance and dimensional stability at high temperatures. It is preferable that it is formed from the polyimide obtained combining these. The porous polyimide film of the present invention is preferably a porous polyimide film made of the following aromatic polyimide from the viewpoints of heat resistance and dimensional stability at high temperatures.

(I) an aromatic polyimide comprising at least one tetracarboxylic acid unit selected from the group consisting of a biphenyltetracarboxylic acid unit and a pyromellitic acid unit, and an aromatic diamine unit,
(Ii) an aromatic polyimide comprising a tetracarboxylic acid unit and at least one aromatic diamine unit selected from the group consisting of a benzenediamine unit, a diaminodiphenyl ether unit and a bis (aminophenoxy) phenyl unit, and / or
(Iii) at least one tetracarboxylic acid unit selected from the group consisting of biphenyltetracarboxylic acid units and pyromellitic acid units, and at least selected from the group consisting of benzenediamine units, diaminodiphenyl ether units and bis (aminophenoxy) phenyl units An aromatic polyimide composed of a kind of aromatic diamine unit.
Next, the manufacturing method of the porous polyimide film of this invention is demonstrated.
The method for producing a porous polyimide film of the present invention is a polyamic acid solution (A) comprising 0.3 to 60% by mass of a polyamic acid composed of a tetracarboxylic acid unit and a diamine unit and 40 to 99.7% by mass of an organic polar solvent. And a polyamic acid solution composition containing 0.1 to 200 parts by mass of an organic compound (B) having a polar group or a polymer compound (C) having a polar group in a side chain with respect to 100 parts by mass of the polyamic acid. Casting a product into a film and immersing or contacting it in a coagulation solvent containing water as an essential component to produce a polyamic acid porous membrane, and the polyamic acid porous membrane obtained in the step Including a step of imidization by heat treatment. Here, the said organic compound (B) and the said high molecular compound (C) are organic compounds which accelerate | stimulate permeation of water into the film-form casting of the said polyamic acid solution composition.

  The polyamic acid is composed of a tetracarboxylic acid unit and a diamine unit, and is a polyimide precursor or a partially imidized polyimide precursor. The polyamic acid can be obtained by polymerizing tetracarboxylic dianhydride and diamine. By polyimidic acid thermal imidization or chemical imidization, ring closure can be made into polyimide. The polyimide in the present invention preferably has an imidization ratio of about 80% or more, preferably 85% or more, more preferably 90% or more, and still more preferably 95% or more.

  Any organic polar solvent can be used as a solvent for polymerizing the polyamic acid, and p-chlorophenol, o-chlorophenol, N-methyl-2-pyrrolidone (NMP), pyridine, N, N-dimethylacetamide Organic polar solvents such as (DMAc), N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, phenol, cresol and the like can be used, and in particular, N-methyl-2-pyrrolidone (NMP), N, N-dimethyl Acetamide (DMAc) can be preferably used. As the tetracarboxylic dianhydride and diamine, those described above can be preferably used.

  A polyamic acid can be manufactured by arbitrary methods using tetracarboxylic dianhydride, diamine, said organic polar solvent, etc. For example, tetracarboxylic dianhydride and diamine are approximately equimolar, preferably at a temperature of about 100 ° C. or lower, more preferably 80 ° C. or lower, still more preferably 0 to 60 ° C., particularly preferably 20 to 60 ° C. Can react for about 0.2 hours or more, more preferably 0.3 to 60 hours to produce a polyamic acid solution.

  When preparing a polyamic acid solution, an arbitrary molecular weight adjusting component may be added to the reaction solution for the purpose of adjusting the molecular weight.

  The logarithmic viscosity (30 ° C., concentration: 0.5 g / 100 mL, solvent: NMP) of the polyamic acid may be any viscosity that can produce the porous polyimide film of the present invention. In the method of the present invention, it is preferable to use a polyamic acid having a logarithmic viscosity of preferably 0.3 or more, more preferably 0.5 to 7.

  As the polyamic acid, even if a part of the amic acid is imidized, it can be used as long as it does not affect the present invention.

  The polyamic acid solution (A) comprises 0.3 to 60% by mass of polyamic acid and 40 to 99.7% by mass of organic polar solvent. When the content of the polyamic acid is less than 0.3% by mass, the film strength when the porous polyimide film is produced is lowered, and when it exceeds 60% by mass, the material permeability of the porous polyimide film is lowered. The content of the polyamic acid in the polyamic acid solution (A) is preferably 1 to 30% by mass, more preferably 2 to 15% by mass, still more preferably 5 to 10% by mass, and the organic in the polyamic acid solution (A). The content of the polar solvent is preferably 70 to 99% by mass, more preferably 85 to 98% by mass, and still more preferably 90 to 95% by mass.

  The polyamic acid solution (A) may be a solution obtained by polymerizing tetracarboxylic dianhydride and diamine in the presence of an organic polar solvent, or a solution obtained by dissolving polyamic acid in an organic polar solvent. It may be.

  The polyamic acid solution composition includes a composition containing a polyamic acid solution (A) and an organic compound (B) having a polar group, a polyamic acid solution (A) and a polymer compound (C) having a polar group. And a composition containing a polyamic acid solution (A), an organic compound (B) having a polar group, and a polymer compound (C) having a polar group, preferably a polyamic acid solution (A ) And an organic compound (B) having a polar group, or a composition containing a polyamic acid solution (A) and a polymer compound (C) having a polar group.

The organic compound (B) having a polar group and the polymer compound (C) having a polar group are organic compounds that promote the penetration of water into the film-like casting of the polyamic acid solution composition. By promoting the penetration of water into the film-like cast product of the polyamic acid solution composition, macrovoids having an average pore diameter of 10 to 500 μm can be formed in the polyimide film.
The organic compound (B) having a polar group is a polyamic acid in which the solidification of the polyamic acid does not contain the organic compound (B) having a polar group in the step of immersing the film-like casting of the polyamic acid solution composition in the coagulation bath. What is necessary is that the effect accelerated compared with the solidification process of the polyamic acid in the acid solution composition is recognized, especially the effect of promptly promoting the solidification in the film thickness direction from the surface in contact with the coagulation bath to the inside. It is preferable that it has. Therefore, the organic compound (B) having a polar group is preferably a compound that does not react or hardly reacts with the polyamic acid in view of the above characteristics.

  Examples of the organic compound (B) having a polar group include organic compounds having a carboxylic acid group such as benzoic acid and phthalic acid, organic compounds having a nitrile group, organic compounds having a hydroxyl group, and organic compounds having a sulfonic acid group. These can be used alone or in combination of two or more. In particular, the organic compound having a polar group is preferably an organic compound having a carboxylic acid group such as benzoic acid or phthalic acid.

  The polymer compound (C) having a polar group is a polyamic acid in which solidification of the polyamic acid does not contain the polymer compound (C) in the step of immersing the film casting of the polyamic acid solution composition in a coagulation bath. It is sufficient that the effect promoted as compared with the solidification process of the polyamic acid in the solution composition is observed, and in particular, the effect of promptly promoting the coagulation in the film thickness direction from the surface in contact with the coagulation bath to the inside. It is preferable to have it. Therefore, the polymer compound (C) is preferably a compound that does not react or hardly reacts with the polyamic acid in view of the above characteristics.

Examples of the polymer compound (C) having a polar group include a polymer having a polar group such as a CN group, OH group, COOH group, SO3H group or NH2 group in the side chain (for example, a vinyl polymer). These can be used alone or in combination of two or more. In particular, as the polymer compound (C) having a polar group, a vinyl polymer having a polar group such as a CN group, OH group, COOH group, SO ₃ H group, NH ₂ group in the side chain such as polyacrylonitrile is preferable. .

  In the polyamic acid solution composition, the content of the polymer compound (C) is 0.1 to 200 parts by mass, preferably 1 to 150 parts by mass with respect to 100 parts by mass of the polyamic acid, from the viewpoint of forming macrovoids. More preferably, it is 10-100 mass parts, More preferably, it is 20-70 mass parts.

  In the polyamic acid solution composition, when the organic compound (B) having a polar group and the polymer compound (C) having a polar group are contained, the total of the organic compound (B) and the polymer compound (C) The content of is from 0.1 to 200 parts by weight, preferably from 1 to 150 parts by weight, more preferably from 10 to 100 parts by weight, still more preferably from 20 parts by weight, based on 100 parts by weight of the polyamic acid, from the viewpoint of macrovoid formation. -70 mass parts.

The polymer compound (C) having a polar group is at least one of the following features (C1) to (C4), preferably the following features (C1) to (C3), more preferably the following features (C1) to (C4). It is preferable to provide all of the above.
(C1) Insoluble or hardly soluble in water, coagulation solvent and / or organic polar solvent.
(C2) Decomposing in the thermal imidization step.
(C3) The polymer compound (C) having a polar group is homogeneously suspended in the polyamic acid solution composition.
(C4) Incompatible with polyamic acid.
Although the mechanism of action of the polymer compound (C) having a polar group is not clear, it is considered as follows.

c1) The polymer compound (C) remains as an incompatible material in the polyamic acid. Part or all of the polymer compound (C) is eluted in a coagulation bath when it is immersed or brought into contact with a coagulation solvent to produce a porous film of polyamic acid, and further decomposed in a process of heating imidization. The As a result, in the partition of the macrovoid layer and the surface layers (a) and (b) of the polyimide film, the portions where the removed polymer compound (C) was present formed pores, and the polyimide membrane material permeation Improves.
And / or c2) The substance permeability of the polyimide film is improved by affecting the coagulation process, such as promoting the coagulation of the polyamic acid solution composition.
When the polymer compound (C) having a polar group is added to the polyamic acid solution composition, the polymer compound (C) is added as it is or in the form of a solution or suspension. be able to.

  In addition, in the production of the polyamic acid solution composition, the solution may become a suspension, but if the homogeneous state can be maintained by stirring for a sufficient time, the production of the polyimide of the present invention Can be used.

  The solution viscosity of the polyamic acid solution composition is preferably 10 to 10000 poise (1 to 1000 Pa · s), more preferably 100 to 3000 poise (10 to 300 Pa) from the viewpoint of ease of casting and film strength. S), more preferably 200 to 2000 poise (20 to 200 Pa · s), particularly preferably 300 to 1000 poise (30 to 100 Pa · s).

(Casting)
In the method for producing a porous polyimide of the present invention, first, a polyamic acid solution composition is cast into a film. The casting method is not particularly limited. For example, the polyamic acid solution composition is used as a dope solution, and the polyamic acid solution composition is formed into a film on a glass plate or a stainless steel plate using a blade or a T-die. Can be cast. In addition, the polyamic acid solution composition is intermittently or continuously cast on a continuous movable belt or drum in the form of a film to continuously produce individual pieces or long-form casts. Can do. The belt or drum may be any one that is not affected by the polyamic acid solution composition and the coagulation solution, and may be made of a metal such as stainless steel or a resin such as polytetrafluoroethylene. Moreover, the polyamic acid solution composition formed into a film form from a T-die can be put into a coagulation bath as it is. Moreover, you may make the one surface or both surfaces of a casting thing contact with gas (air, an inert gas, etc.) containing water vapor | steam etc. as needed.

(Preparation of porous film of polyamic acid)
Next, the casting is immersed or brought into contact with a coagulation solvent containing water as an essential component, and a polyamic acid is precipitated to make a porous film, thereby producing a porous film of polyamic acid. The obtained porous film of polyamic acid is washed and / or dried as necessary.
As the coagulation solvent containing water as an essential component, water or a mixed solution of 5% by mass or more and less than 100% by mass of water and an organic polar solvent of more than 0% by mass and 95% by mass or less can be used. From the viewpoint of ensuring safety such as fire, manufacturing cost, and ensuring the homogeneity of the obtained film, it is preferable to use a coagulation solvent containing water and an organic polar solvent. Examples of the organic polar solvent that may be contained in the coagulation solvent include alcohols such as ethanol and methanol, which are poor solvents for polyamic acid, and acetone.

  When the coagulation solvent is a mixed solution of water and an organic polar solvent, the content of water in 100% by mass of the coagulation solvent is preferably 5% by mass or more and less than 100% by mass, more preferably 20% by mass or more and 100% by mass. Less than, more preferably 30 to 95% by mass, particularly preferably 45 to 90% by mass. The content of the organic polar solvent in 100% by mass of the coagulation solvent is preferably more than 0% by mass and 95% by mass or less, more preferably more than 0% by mass and 80% by mass or less, still more preferably 5 to 70% by mass, Preferably it is 10-55 mass%.

  The temperature of the coagulation solvent may be appropriately selected according to the purpose and used, for example, in the range of -30 to 70 ° C, preferably 0 to 60 ° C, more preferably 10 to 50 ° C.

(Imidization treatment)
Next, the obtained porous film of polyamic acid is imidized to produce a porous polyimide film. Examples of imidization include thermal imidization treatment and chemical imidization treatment. In the present invention, thermal imidization treatment is preferable.

(Thermal imidization treatment)
Thermal imidation treatment is performed by, for example, fixing a porous film of polyamic acid to a support using pins, chucks, pinch rolls, etc. so that the smoothness is not impaired by heat shrinkage, and heating in the atmosphere. Can be performed. The reaction conditions are, for example, a heating temperature of 280 to 600 ° C., preferably 350 to 550 ° C., for 1 to 120 minutes, preferably 2 to 120 minutes, more preferably 3 to 90 minutes, and further preferably 5 to 60 minutes. It is preferable to carry out by appropriately selecting from the time.

  In the method of the present invention, the temperature rise rate in the temperature range of 200 ° C. or higher in the thermal imidization treatment is 25 ° C./min or higher, preferably 50 ° C./min or higher, and the upper limit of the temperature rising rate is particularly limited. Although it is not necessary, when setting the upper limit value of the heating rate, it is 50 to 500 ° C./min, preferably 50 to 400 / min, more preferably 70 to 300 ° C./min, and further preferably 120 to 200 ° C./min. Minutes. By heating at the above temperature increase rate in the temperature range of 200 ° C. or higher where the imidization reaction occurs remarkably, the surface opening ratio and the pore diameter are greatly improved, and the permeability of substances such as gas is greatly improved. A porous polyimide film can be obtained.

  In addition, when using the polyamic acid solution composition containing the high molecular compound (C) which has a polar group, it heats by heating the porous film of polyamic acid more than the thermal decomposition start temperature of the said high molecular compound (C). It is preferable to imidize. The thermal decomposition start temperature of the polymer compound (C) can be measured, for example, in the air at 10 ° C./min using a thermogravimetric apparatus (TGA).

  Normally, when a polyimide film is formed from a cast product of a polyamic acid solution, if a rapid heating and temperature increase is performed, solvent volatilization occurs suddenly and a foaming phenomenon is induced and a good film cannot be obtained. Heating is performed at a moderate temperature increase rate until the solvent evaporates from the solution and the solution becomes a gel. On the other hand, in the case of a porous polyimide film, most of the good solvent is extracted in the dipping process in the poor solvent coagulation bath, which is the process for forming the precursor polyamic acid porous film. Such a foaming phenomenon does not occur. However, when heat treatment is performed at a temperature that is significantly higher than the profile in which the glass transition temperature of the polyamic acid rises as the imidization reaction proceeds, the polymer flows and the pores close, resulting in densification and air flow. The problem that the sex deteriorates arises.

  On the other hand, the present inventors set the rate of temperature increase in the temperature region of 200 ° C. or higher in the thermal imidization treatment of the polyamic acid porous membrane at 50 ° C./min or higher, preferably 70 ° C. or higher, more preferably 100 It has been found that the porous polyimide film of the present invention in which the surface opening ratio and the pore diameter are greatly improved and the permeability of a substance such as a gas is greatly improved can be obtained by setting the temperature to be equal to or higher. Although the mechanism of action that can improve the material permeability by setting the heating rate to 50 ° C./min or more has not yet been clarified, the porosity of the polyamic acid porous membrane having macrovoids is high For this reason, it is presumed that mass transfer that is performed only for densification does not occur, and that the organic compound (B) having a polar group used as a raw material suppresses the flow of polyamic acid molecules.

  When the porous polyimide membrane of the present invention is produced via a polyamic acid solution or a polyimide solution, the type of polymer used, the polymer concentration of the polymer solution, the viscosity, the organic solution, and the like, solidification conditions (the type of the solvent substitution rate adjusting layer, By appropriately selecting the temperature, the coagulation solvent, etc.), the porosity, film thickness, surface average pore diameter, maximum pore diameter, center average pore diameter, and the like can be appropriately designed.

  The porous polyimide film of the present invention may be subjected to a surface treatment of the film by subjecting at least one surface to a corona discharge treatment, a plasma discharge treatment such as a low-temperature plasma discharge or an atmospheric pressure plasma discharge, a chemical etching or the like according to the purpose. Good. Further, the surface layer (a) and / or (b) may be shaved and used. By these treatments, the material permeability, surface pore diameter, and wettability of the membrane can be controlled.

<Layers other than porous layer>
The present invention is composed of two or more layers including at least one porous layer, and layers other than the porous layer used in the present invention are assumed to be non-porous, and a nonporous film may be used. A polyimide film or a polyamide film can be used as the nonporous film.

  As the polyimide film used in the present invention, a multilayer polyimide film having a heat-fusible resin polyimide surface layer on the surface can be used. For example, a two-layer or three-layer structure [heat-adhesive resin polyimide surface layer / polyimide] Layer (/ heat-sealable polyimide surface layer)]. Such a multilayer polyimide film can be obtained, for example, by a method in which a polyimide precursor solution that gives a heat-fusible polyimide film is laminated on at least one surface or both surfaces of a polyimide layer by a coextrusion molding method.

The heat-sealable polyimide surface layer in the heat-sealable multilayer polyimide film is preferably made of a heat-sealable polyimide that can be thermocompression bonded in a temperature range of 250 to 400 ° C. Preferably, the heat-fusible polyimide has a glass transition temperature of 200 ° C to 300 ° C.
The heat-fusible polyimide is preferably 1,3-bis (4-aminophenoxy) benzene (hereinafter sometimes abbreviated as TPE-R) and 2,3,3 ′, 4′-biphenyltetracarboxylic acid. It is produced from a dianhydride (hereinafter sometimes abbreviated as a-BPDA). Further, the heat-fusible polyimide is manufactured from 1,3-bis (4-aminophenoxy) -2,2-dimethylpropane (DANPG) and 4,4′-oxydiphthalic dianhydride (ODPA). . Alternatively, it is produced from 4,4′-oxydiphthalic dianhydride (ODPA) and pyromellitic dianhydride and 1,3-bis (4-aminophenoxy) benzene. Also, from 1,3-bis (3-aminophenoxy) benzene and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, or from 3,3′-diaminobenzophenone and 1,3-bis ( 3-aminophenoxy) benzene and 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride. Further, in the tetracarboxylic acid component, 12 to 25 mol% of 100 mol% is pyromellitic dianhydride, 5 to 15 mol% is 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, The balance is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,3-bis (4-aminophenoxy) benzene is an essential component as a diamine component, and Tg can be observed by DSC measurement A fusible polyimide is also suitable.

  This heat-fusible polyimide can be used in the form of other tetracarboxylic dianhydrides, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2- It may be replaced with bis (3,4-dicarboxyphenyl) propane dianhydride and the like. The heat-fusible polyimide is obtained by reacting each of the above components with another tetracarboxylic dianhydride and another diamine in an organic solvent at a temperature of about 100 ° C. or less, particularly 20 to 60 ° C. Thus, a polyamic acid solution can be used, and this polyamic acid solution can be used as a dope solution.

  The polyamic acid solution that is a precursor of the heat-fusible polyimide is preferably 0.92 to 1.1, particularly 0.98 to 1.1, in terms of the ratio of the number of moles of the acid component to the number of moles of the diamine. In particular, a ratio of 0.99 to 1.1 is preferable. Further, for the purpose of limiting the gelation of polyamic acid, phosphorus stabilizers such as triphenyl phosphite and triphenyl phosphate are 0.01 to 1% based on the solid content (polymer) concentration during polyamic acid polymerization. It can be added in the range of. For the purpose of promoting imidization, a basic organic compound catalyst can be added to the solution. For example, imidazole, 2-imidazole, 1,2-dimethylimidazole, 2-phenylimidazole and the like are 0.01 to 20% by weight, particularly 0.5% with respect to the polyamic acid (solid content). It can be used at a ratio of -10% by weight. Since these form a polyimide film at a relatively low temperature, they are used to avoid imidation becoming insufficient. For the purpose of stabilizing the adhesive strength, an organoaluminum compound, an inorganic aluminum compound, or an organotin compound may be added to the heat-sealable aromatic polyimide raw material dope. For example, aluminum hydroxide, aluminum triacetylacetonate, or the like can be added in an amount of 1 ppm or more, particularly 1 to 1000 ppm as an aluminum metal with respect to polyamic acid (solid content).

  The organic solvent used for the production of the polyamic acid is N-methyl-2-pyrrolidone, N, N-dimethylformamide, any of highly heat-resistant aromatic polyimide and heat-sealable aromatic polyimide. N, N-dimethylacetamide, N, N-diethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, N-methylcaprolactam, cresols and the like can be mentioned. These organic solvents may be used alone or in combination of two or more.

  The polyimide forming the polyimide layer excluding the heat-fusible polyimide surface layer of the multilayer polyimide film of the present invention is preferably a high heat-resistant polyimide having a glass transition temperature of 250 ° C. or higher or not exhibiting a glass transition temperature. Is preferred. The high heat-resistant polyimide is preferably 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes simply referred to as s-BPDA) and paraphenylenediamine (hereinafter simply referred to as PPD). And sometimes 4,4′-diaminodiphenyl ether (hereinafter simply abbreviated as DADE) and / or pyromellitic dianhydride (hereinafter simply abbreviated as PMDA). There are also. In this case, the PPD / DADE (molar ratio) is preferably 100/0 to 85/15. Moreover, it is preferable that s-BPDA / PMDA is 100: 0-50 / 50.

  The high heat-resistant polyimide is produced from pyromellitic dianhydride, paraphenylenediamine and 4,4'-diaminodiphenyl ether. In this case, the DADE / PPD (molar ratio) is preferably 90/10 to 10/90.

  Further, the high heat-resistant polyimide includes 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), paraphenylenediamine (PPD), and 4,4. It is produced from '-diaminodiphenyl ether (DADE). In this case, it is preferable that BTDA in acid dianhydride is 20 to 90 mol%, PMDA is 10 to 80 mol%, PPD in diamine is 30 to 90 mol%, and DADE is 10 to 70 mol%.

  In the high heat-resistant polyimide, other types of aromatic tetracarboxylic dianhydrides and aromatic diamines such as 4,4'-diaminodiphenylmethane may be used as long as the physical properties are not impaired.

  In the co-extrusion-casting film forming method, for example, a heat-fusible polyimide precursor solution is co-extruded on one side or both sides of the polyamic acid solution of the high heat-resistant polyimide, and this is stainless steel mirror surface, belt surface, etc. It is preferable to cast and apply it on the surface of the support and to make it a semi-cured state or a dried state before it at 100 to 300 ° C. This semi-cured state or an earlier state means that it is in a self-supporting state by heating and / or chemical imidization. The co-extrusion is, for example, supplied to a two-layer or three-layer extrusion die by a co-extrusion method described in JP-A-3-180343 (Japanese Patent Publication No. 7-102661) and cast on a support. Can be done.

  A glass transition of the heat-fusible polyimide is formed by laminating a polyamic acid solution giving a heat-fusible polyimide on one or both sides of the extrudate layer giving the high heat-resistant polyimide, forming a multi-layer film and drying it. If heating and drying and imidization are performed at a temperature not lower than the temperature (Tg) and lower than the temperature at which deterioration occurs, preferably at a maximum heating temperature of 375 ° C. or higher and 550 ° C. or lower, heat is applied to one or both sides of the high heat resistant polyimide. A multilayer polyimide film having a fusible polyimide surface layer can be suitably obtained.

  In the multilayer polyimide film having the heat-fusible polyimide surface layer of the present invention, the thickness of the polyimide layer (base layer) is about 5 to 100 μm, particularly about 7 to 50 μm. The thickness of the heat-fusible polyimide surface layer is preferably 1 to 10 μm, particularly preferably 2 to 5 μm. If it is less than 1 μm, it is difficult to obtain good adhesion performance by heat fusion. On the other hand, if it exceeds 10 μm, it cannot be used but is not particularly effective. Rather, the heat resistance of the obtained polyimide heater is lowered.

  The multilayer polyimide film having a heat-fusible polyimide surface layer has a thickness of 10 to 100 μm, particularly 10 to 50 μm, and preferably 10 to 25 μm. If it is less than 10 μm, it is difficult to handle the produced film, and even if it is thicker than 100 μm, there is no particular effect, and when the space excluding the metal of the heating element is filled with the heat-bonding multilayer polyimide film on one side by heating and pressing with the heating element It becomes difficult and disadvantageous.

The thermoplastic polyimide resin of the present invention is one that melts in the same manner as the heat-sealable polyimide surface layer when the polyimide heater is heat-sealed, and preferably exhibits an appropriate fluidity at that temperature. It is. Accordingly, those having a glass transition temperature of 150 to 300 ° C., preferably 200 to 300 ° C. are suitable, and polyimide having two or more ether bonds in the main chain of the repeating unit of polyimide is suitable. For example, the acid component is 2,2′-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride, the diamine component is polyimide obtained from m-phenylenediamine, and the acid component is s-BPDA. Mixture of a-BPDA (mixing ratio is s-BPDA / a-BPDA = about 8/2 in molar ratio), polyimide obtained from 1,3-bis (4-aminophenoxy) benzene as diamine component, Preferable examples include merit acid anhydride and a polyimide whose diamine component is obtained from 4,4′-bis (3-aminophenoxy) biphenyl.
The thermoplastic polyimide resin is not limited, but a film having a thickness of 10 μm to 5 mm, preferably about 10 μm to 500 μm, can be suitably used by stacking as necessary.

  Examples of the polyamide film used in the present invention include polyamide 6, polyamide 66, polyamide 6.66 copolymer, polyamide 12 and the like. Among these, polyamide 6 is preferable.

<Laminate>
The laminate of the present invention may have a two-layer structure in which a porous layer and a layer other than the porous layer are laminated one by one, and a layer other than the porous layer is laminated on both sides of the porous layer as a core layer. It may be a three-layer structure or a further multilayer structure such as a four-layer structure or a five-layer structure. In the case of a laminate having a two-layer structure, the thickness of the porous layer is preferably 1 to 500 μm, more preferably 2 to 300 μm, particularly preferably 5 to 150 μm, and the thickness of layers other than the porous layer is preferably It is 0.5 to 200 μm, more preferably 1 to 100 μm, and particularly preferably 2 to 75 mm. In the case of a laminate having a three-layer structure, the thickness of the porous layer is preferably 1 to 300 μm, more preferably 2 to 200 μm, particularly preferably 5 to 100 μm, and the thickness of the layers other than the porous layer is Preferably it is 0.5-150 micrometers, More preferably, it is 1-100 micrometers, Most preferably, it is 2-50 micrometers, and the thickness of layers other than the porous layer of both surfaces of a porous layer may be the same, and may differ.

<Physical properties of the laminate>
The laminate of the present invention is a flexible laminate including a porous layer having practical heat resistance and high dimensional stability.

The practical heat resistance of the laminate is confirmed by the thermal conductance of the laminate, and the thermal conductance is preferably 1000 W / m ² K or less, more preferably 750 W / m ² K or less, and 500 W / More preferably, it is m ² K or less. 1000 W / m ² K or less is preferable in that practical heat insulating properties can be obtained even with a thickness of 1 mm or less.

  The dimensional stability of the laminate is confirmed by the linear expansion coefficient of the laminate, and the linear expansion coefficient of the laminate is preferably 100 ppm / K or less in the direction perpendicular to the thickness direction at 200 ° C. or less. 70 ppm / K or less is more preferable, and 50 ppm / K or less is more preferable. When the linear expansion coefficient is 100 ppm / K or less, for example, it is easy to use even in a place where a large number of electronic components are arranged in a narrow space such as the inside of an electronic device, and can also be used as a circuit board. preferable.

  The porosity of the entire laminate may be appropriately selected depending on the purpose of use, but is preferably 40% to 95%, more preferably 50% to 90%, and 60% to 80%. % Is more preferable. When the porosity is 40% to 95%, it has practical heat resistance and can maintain the strength of the laminate itself.

<Method for producing laminate>
Although the manufacturing method of the laminated body of this invention is not specifically limited, It can manufacture with the following method.
1) A polyimide film having a heat-fusion layer and a polyimide porous film are laminated and heated and pressed to produce a laminate having a two-layer structure.
2) A polyimide film having a heat fusion layer is disposed on both sides of the polyimide porous film, laminated, and heated and pressed to produce a laminate having a three-layer structure.
3) Five layers of a polyimide film having a heat-fusible layer and a polyimide porous film are alternately laminated so that the polyimide film becomes the outermost surface, and a laminate having a five-layer structure is produced by heat pressing.
4) A laminated body is produced by bonding the layers using an adhesive.
5) After the surface of the film to be laminated is irradiated with plasma, electron beam or the like to be in a chemically active state, it is bonded with another film to produce a laminate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

<Evaluation of porous layer (porous film)>
1) Film thickness of porous film The film thickness was measured with a contact-type thickness meter.

2) Porosity of porous film The film thickness and mass of the porous film cut out to a predetermined size were measured, and the porosity was determined from the mass per unit area according to the following formula (1).

Porosity = S × d × D / w × 100 (1) (where S is the area of the porous film, d is the film thickness, w is the measured mass, and D is the polyimide density) (The density of polyimide is 1.34 g / cm 3.)

3) Gas permeability of porous film The Gurley value (seconds required for 100 cc of air to pass through the membrane under a pressure of 0.879 g / mm ² ) was measured according to JIS P8117.

<Evaluation of layers other than porous layer (non-porous film)>
1) Film thickness of non-porous film The film thickness was measured with a contact-type thickness meter.

<Thermal conductance of the laminate>
The thermal conductivity was measured at room temperature by using an eye phase mobile 1u manufactured by Eye Phase Co., Ltd., and the thermal conductance was calculated.

<Linear expansion coefficient of laminate>
Linear expansion coefficient (50 to 200 ° C.) measurement: The sample was measured with a TMA apparatus (tensile mode, 2 g load, sample length 10 mm, 20 ° C./min).

The following films were prepared.
Polyimide porous membrane A
Polyimide porous membrane B
Upilex VT (manufactured by Ube Industries)
Kapton 100H / V (manufactured by Toray DuPont)
Polytetrafluoroethylene (PTFE) porous membrane (Millipore, Omnipore JVWP)
The respective film properties are shown in Table 1.

<Example 1>
1) Upilex VT of 5 × 10 cm size and polyimide porous membrane A are laminated in the order of Upilex VT, polyimide porous membrane A, and Upilex VT, and heated and pressed at 280 ° C. and 6 MPa pressure for 5 minutes. A layered laminate was obtained. The laminate did not peel even after being immersed in ethanol for 5 minutes. The film thickness, apparent porosity, thermal conductance, and linear expansion coefficient were measured. The results are shown in Table 2.
2) Upilex VT and polyimide porous membrane B with a size of 5 × 10 cm are laminated in the order of Upilex VT, polyimide porous membrane B, and Upilex VT, and heated and pressed at 280 ° C. under a pressure of 2 MPa for 10 seconds. A layered laminate was obtained. The laminate did not peel even after being immersed in ethanol for 5 minutes. The film thickness, apparent porosity, thermal conductance, and linear expansion coefficient were measured. The results are shown in Table 2.
3) Upilex VT of 5 × 10cm size and polyimide porous membrane B are laminated in the order of Upilex VT, polyimide porous membrane B, Upilex VT, polyimide porous membrane B, and Upilex VT at a pressure of 2 MPa at 280 ° C. Heat pressing was performed for 10 seconds to obtain a laminate having a five-layer structure. The laminate did not peel even after being immersed in ethanol for 5 minutes. The film thickness, apparent porosity, thermal conductance, and linear expansion coefficient were measured. The results are shown in Table 2.

<Comparative Example 1>
The thermal conductance and linear expansion coefficient of Kapton 100H / V film were measured. The results are shown in Table 2.
<Comparative example 2>
The thermal conductance and linear expansion coefficient of the polyimide porous membrane A were measured. The results are shown in Table 2.
<Comparative Example 3>
The thermal conductance and linear expansion coefficient of the polyimide porous membrane B were measured. The results are shown in Table 2.
<Comparative Example 4>
The thermal conductance and linear expansion coefficient of the PTFE porous membrane were measured. The results are shown in Table 2.

  The laminated body can be used as a wide range of basic materials such as low dielectric constant circuit boards, high frequency circuit boards, electromagnetic wave control materials such as electromagnetic wave shields and electromagnetic wave absorbers by making use of the holes. In addition, the laminate including the porous layer is used as a heat insulating sheet for protecting electronic components that are vulnerable to heating in thin televisions, mobile devices, notebook personal computers, and the like. Moreover, it can be used as a wide range of basic materials such as low dielectric constant circuit boards, high frequency circuit boards, electromagnetic wave control materials such as electromagnetic wave shields and electromagnetic wave absorbers, etc. by utilizing the holes. It can also be used to protect automotive electronic devices from heat.

Claims (4)

It is a laminate of two or more layers including at least one porous layer,
Layers other than the porous layer are non-porous polyimide layers,
The porous layer is a polyimide porous layer;
The laminate has a thermal conductance in the thickness direction of 1000 W / m ² K or less and a linear expansion coefficient in the direction perpendicular to the thickness direction at 200 ° C. or less of ± 100 ppm / K% or less. A manufacturing method comprising:
The manufacturing method of a laminated body including the process of adhere | attaching the polyimide film which has a heat-fusion layer, and a polyimide porous membrane with a heat press.   The method for producing a laminate according to claim 1, wherein the laminate has three or more layers, the porous layer is an inner layer, and the outermost layer is a nonporous film.   The method for producing a laminate according to claim 1 or 2, wherein the porosity of the entire laminate is 40% or more. The porous layer is
A three-layer polyimide porous layer having two surface layers (a) and (b) and a macrovoid layer sandwiched between the surface layers (a) and (b),
The macrovoid layer has a partition wall bonded to the surface layers (a) and (b), and an average pore diameter in the film plane direction surrounded by the partition wall and the surface layers (a) and (b) is 10 to 500 μm. Having a plurality of macrovoids,
The partition wall of the macrovoid layer has a thickness of 0.1 to 50 μm and has a plurality of pores having an average pore diameter of 0.01 to 50 μm, and each of the surface layers (a) and (b) has a thickness. Is 0.1 to 50 μm, at least one surface layer has a plurality of pores having an average pore diameter of 0.01 to 200 μm, and the partition walls of the macrovoid layer and the surface layers (a) and (b) And the pores in the communication with the macro voids,
The method for producing a laminate according to any one of claims 1 to 3, wherein the laminate is a porous film having a total film thickness of 5 to 500 µm and a porosity of 50 to 95%.