JP2001329104A - Porous film of para-type aromatic polyamide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a heat resistant porous film having large sized pores on the surface and excellent in material permeability and impregnating properties. SOLUTION: This para-type aromatic polyamide porous film is characterized in that (1) the total area of open pores presenting on the surface of the film (the total area of open pores) is >=30% of the total area of the surface (the total surface area), (2) the area of pores having >5 μm diameters among the open pores is >=30% of the total area of open pores, (3) the air permeability of the film is 0-10 sec/(100 ml*μm* cm2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention has a large surface opening,
The present invention relates to a heat-resistant porous sheet having excellent material permeability, impregnation and adhesion. More specifically, the present invention relates to a heat-resistant para-type aromatic polyamide porous sheet having a large surface opening and excellent in material permeability and impregnation. Further, the present invention relates to a laminated circuit board and a flexible printed board using such a porous sheet as a core agent.

[0002]

2. Description of the Related Art With the recent rapid development of high-density information technology, dielectrics used for laminated substrates for electronic circuits have been required to have not only dimensional stability and workability but also thinner. And low dielectric constant have been required. Aromatic polyamide fiber paper is superior to paper base made of other materials in heat resistance, electrical insulation, heat resistance dimensional stability, light weight, etc. Is being used as a base material. For example,
Paper made of polymetaphenylene isophthalamide staple fiber (Cornex; manufactured by Teijin Limited) and polymetaphenylene isophthalamide pulp (fibrid) "electrically insulating paper (JP-A-2-236907 and JP-A-2-106)
840)) has been proposed. In addition, it is composed of polyparaphenylene terephthalamide short fiber (Kevlar; manufactured by DuPont), copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide short fiber (Technola; manufactured by Teijin Limited) and an organic resin binder. Aromatic polyamide fiber paper “Resin impregnated sheet (Japanese Unexamined Patent Publication No.
No. 92233) and a method for producing aromatic polyamide fiber paper (Japanese Patent Application Laid-Open No. 2-47392).

[0003] However, although the former fiber paper is excellent in heat resistance, when heat treated at a high temperature of 250 ° C or more, it not only shrinks to cause dimensional change, but also has a high equilibrium moisture content (moisture content) of the fiber and The content of impurity ions is also high. Therefore, it is inferior in electric insulation especially when held under high humidity for a long period of time, and cannot be used as a base material for electric insulation which requires high reliability. On the other hand, the latter fiber paper is excellent in terms of the equilibrium moisture content of fibers and the content of impurity ions, but since only organic resin is used as a binder component, the binder component is not used in the fiber paper manufacturing process. It migrates to the front and back sides of paper and becomes unevenly distributed. As a result, the amount of the binder component present in the middle layer of the paper becomes very small, and there is a problem that the uniformity in the thickness direction of the obtained fiber paper is reduced and the reliability is deteriorated.

When such a fiber paper is used as a base material for a laminate for an electric circuit board, its production process, particularly, a prepreg process of impregnating and drying a compounded varnish such as an epoxy resin and a process of laminating and molding the prepreg product, etc. As a result, the variation in the impregnation amount (particularly in the thickness direction) and the adhesion amount of the compounded varnish increases. In addition, a part of the resin for the binder is melted to cause a decrease in the adhesive strength between the fibers, which may cause the paper base material to be cut. In particular, there is a problem that the laminate for an electric circuit board is deformed after the solder reflow process, which is performed at a high temperature, after completion of the solder reflow process.

[0005] Further, since paper and nonwoven fabric are materials composed of fibers, it is difficult to manufacture them unless the thickness of the fibers is sufficient. Conventionally, a polyimide film has been used for a flexible substrate, and this is a material having both good heat resistance and low water absorption. However, it has been pointed out that this material is very expensive and expensive, and at the same time has poorer adhesion to copper foil.

[0006] As a substitute for the nonwoven fabric of aramid, there is a porous film of aramid. Examples of aramid porous films that have been studied so far include, for example, JP-A-53-74572, a method of forming a coacervation composition by adding a poor solvent to a polymer dope and coagulating the polymer dope to form a film. Is stated. However, according to this method, only a film having a pore size of several tens of nanometers to sub-μm is obtained as the para-type aromatic polyamide. In Japanese Patent Application Laid-Open No. 53-144974, a polyamide imparting a liquid crystalline dope is sufficiently fibrillated at the time of film formation, and then is torn and stretched in a wet coagulation bath in a direction perpendicular to the fibril direction to be porous. The method is described. However, in this method, the anisotropy of the fibrils is basically apt to remain, and the pore size thereof is on the order of sub-μm. Thus, a porous film having a sufficiently large and excellent impregnation property has not been obtained.

On the other hand, in Japanese Patent Application Laid-Open No. 4-25535,
By wet-forming a compatible polymer blend,
We have succeeded in obtaining a porous film having a pore size of μm level. However, in this case, the resin other than aramid having a low glass transition temperature Tg is left to lower the thermal dimensional stability, and it is not preferable to use the resin as a material requiring the thermal dimensional stability. Japanese Patent Application Laid-Open No. 9-188740 discloses a method of forming aramid fibrils in the presence of a cross-linking material to obtain a porous body. However, as described above, it is difficult to control the orientation of the fibrils, and it is difficult to obtain one having good dimensional stability. Further, even with this, it is not possible to obtain a material having pores of a sufficient size and excellent in impregnation.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and have reached the present invention. That is, the present invention has the following formula (1) - (OC-Ar 1 -CO-NH-Ar 2 -NH) - (1) ( in the formula, Ar _1, Ar ₂ each independently have a substituent A porous aromatic polyamide having a repeating unit represented by the formula (1), which has a repeating unit represented by the following formula: wherein the total area of the pores present on the surface of the film is as follows: The total area of the opening is 30% or more of the total area of the surface (the total surface area), and the area of the opening having a pore diameter of 5 μm or more is 30% of the total area of the opening. And the air permeability of the film is 0 to 10 sec / (100 ml * μ
m * cm ² ), a para-type aromatic polyamide porous film, a prepreg using such a polyamide porous film, and a filter using such a polyamide porous film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The para-type aromatic polyamide of the present invention has a repeating unit represented by the above formula (1), and the aromatic group having 6 to 20 carbon atoms has an ether group in its main chain. , An aromatic group having 6 to 20 carbon atoms which may have a phenyl group, for example, p-xylylenediamine, p-, m-, o-phenylene, oxydiphenylene, diphenylmethane, diphenylpropane, etc. And aromatic groups derived from aromatic diamines or aromatic dicarboxylic acids, and mixtures thereof.

The substituents of these aromatic groups include, for example, a halogen atom such as a fluorine atom and a chlorine atom, and / or a methyl group, an ethyl group, an n,
linear or branched C 1 -C 1 groups such as i-propyl group, n, s, t-butyl group, pentyl group, and hexyl group;
The alkyl group may be 6, and the number of substituents may be a part or all of the hydrogen atoms of the aromatic group and may be a numerical value within a range that does not disturb the object of the present invention.

Among them, the aromatic group is preferably an aromatic group having 6 to 10 carbon atoms which may have a substituent. Specifically, for example, the following formula (A) ) And / or (B)

[0012]

Embedded image

The aromatic group represented by

In particular, in the para-type aromatic polyamide of the present invention, at least 80 mol% of its repeating units are represented by the following formula (2)-(NH-A-NHCO-Ar-CO)-(2) A is an aromatic group represented by the above formula (A);
Represents an aromatic group represented by the above formulas (A) and (B)
And (B) are aromatic groups having a ratio (A) / ((A) + (B)) of from 0.3 to 0.7, and these aromatic groups have some or all of their hydrogen atoms. It may be substituted with a halogen atom and / or an alkyl group having 1 to 6 carbon atoms. The para-type aromatic polyamide represented by ()) can be mentioned as a more preferable one.

The para-type aromatic polyamide used in the present invention has a high degree of orientation and a suitable degree of crystallinity, and can be highly stretched. Therefore, it is possible to produce a target film with sufficient strength and dimensional stability and further with high productivity. On the other hand, it is more preferable for the purpose of the present invention because it has higher thermoplasticity than the paracrystalline aromatic polyamide having high crystallinity and thus has excellent smoothness of a processed end face in laser processing and excellent workability. The para-type aromatic polyamide of the present invention may be synthesized in any manner. For example, although not limited thereto, a dope of a polymer polymerized by a solution polymerization method may be used, or a polymer obtained by polymerization by interfacial polymerization may be used. The para-type aromatic polyamide of the present invention has, for example, p-, m-, for adjusting solubility, crystallinity and heat resistance, in addition to the main components.
-, O-phenylenediamine, oxydiaminophenylene, diaminophenylmethane, aromatic diamines such as diaminophenylpropane, isophorone diamine, various alkylene diamines, such as diamines and terephthalic acid, isophthalic acid, aromatic dicarboxylic acids such as phthalic acid, An alkylene dicarboxylic acid such as adipic acid or butanedicarboxylic acid may be contained as a copolymer component, or a polymer composed of the above components may be blended.

The porous film of the present invention may be produced by any method. In particular, the blended dope of the para-type aromatic polyamide and the soluble polymer is coagulated to form a microphase-separated structure, A desired porous film can be obtained by a method of extracting polyamide. At this time, as the soluble resin, polycarbonate,
Polyether sulfone, polyvinyl pyrrolidone, polyvinyl chloride, polystyrene and the like can be used. At this time, by changing the ratio between the soluble resin and the para-type aromatic polyamide, it is possible to adjust the pore diameter and the porosity of the opening on the film surface based on the porosity. The ratio varies depending on each resin, but in order to obtain a porous film having sufficient impregnating property, the ratio of the soluble resin to the total amount of the polymer is preferably more than 40% and less than 90%.

At this time, any solvent may be used as long as it can dissolve both the para-aromatic polyamide and the soluble resin. From the viewpoint of solubility and handleability, use of an amide solvent is preferred, and NMP is more preferred. (N-methyl-2-
Pyrrolidone) and DMAC (dimethylacetamide). The blend polymer dope can be formed by a film forming method such as a dry or wet film forming method. In this method, since the porous structure is obtained by transferring the microphase-separated structure of the polymer, it is possible to obtain a porous body satisfactorily by either the wet method or the dry method when solidifying the molding dope. .

The film may contain any additives for improving the physical properties. Such materials include antioxidants, plasticizers, flame retardants, lubricants, pigments, heat stabilizers, various fillers, and soluble resins remaining after extraction. The soluble resin may be directly extracted from the film obtained by coagulation, but by stretching, a porous film having higher porosity and a larger pore diameter can be obtained. In stretching, a sufficient opening can be obtained by uniaxial stretching, but biaxial stretching is preferable because anisotropy of dimensional change can be eliminated.

In the thus obtained film, the total area of the apertures present on the surface of the film (total aperture area) is 30% or more of the total area of the surface (total surface area). Among the apertures, the area of the aperture having a diameter of 5 μm or more is 30% or more of the total aperture area. Here, the ratio (%) of the total area of the apertures present on the surface of the film (total surface area) with respect to the total area of the film surface (total surface area) is as follows. In the surface image obtained by
00 μm × 600 μm is extracted, the total aperture area is calculated by image analysis, and calculated as a ratio to the total image area.

In particular, the ratio of the total open area is 3
The content of 5% or more is preferable because more excellent material permeability and impregnation can be obtained. Further, having a pore diameter of 5 μm or more means that the porous film of the present invention has a radius of 5 μm in a surface image obtained by SEM photographing at 200 times magnification.
It means that the circle of m fits in the opening. Above all, it is preferable that the area of the aperture having a pore diameter of 10 μm or more is 40% or more of the total aperture area, because more excellent material permeability and impregnation can be obtained. .

The porous film of the present invention has an air permeability of 0 to 1
0 sec / (100 ml * μm * cm ² ). 10 sec
If it exceeds / (100 ml * μm * cm ² ), it is not possible to obtain a film which is the object of the present invention and has excellent substance permeability, impregnation and adhesion. In the present invention, "air permeability" is defined by JIS
Using the Gurley measuring device described in -8117, 645m
It is a value obtained by dividing the time required for 100 ml of air to pass through a film having an area of m ² by the thickness of the film and the film area. The porous film of the present invention has a porosity of 3
It is desirable to be in the range of 0 to 80%. Here, the porosity is a numerical value represented by the following equation.

Porosity (%) = (1− (basis density (g /
cm ² ) / thickness (cm)) * 100 If this value is lower than 30%, it is difficult to obtain sufficient air permeability,
If it exceeds 80%, it is difficult to obtain sufficient strength. In addition, by having such a pore structure and permeation properties, it is possible to smoothly impregnate a curable resin when used as a prepreg, and furthermore, when used as a laminate, it is preferable because an anchor effect on an adhesive surface is sufficiently exhibited. . The porous film of the present invention thus obtained is
Since it has excellent heat resistance and good substance permeability, it can be naturally used as a filtration membrane (filter). Furthermore, since good liquid impregnation can be performed by such a material permeability, epoxy resin, impregnated with a thermosetting resin such as an unsaturated polyester resin, can be favorably used as a prepreg, and further, for example, a circuit board or It can be used as a laminate or the like.

[0023]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In addition, the measuring method using a film in an Example is as follows. (1) Air permeability sec / (100 ml * μm * cm ² ) Using a Gurley measuring device described in JIS-8117, 6
This is a value obtained by dividing the time required for 100 ml of air to pass through a film having an area of 45 mm ² by the film thickness and the film area.

(2) Measurement of physical properties of film strength (Mpa) A sample film having a width of 10 mm was set on a tensile tester so that the distance between chucks was 100 mm, and the temperature was set at 23 ° C. and 50 mm.
A tensile test was conducted at a tensile speed of 10 mm / min under the conditions of% RH, and the Young's modulus (Mpa), strength (Mpa), and elongation (%) in the machine direction (MD) and the transverse direction (TD) were measured. (3) The ratio (%) of the total aperture area to the total surface area and 5
Percentage (%) of the area of the opening having a pore diameter of not less than μm to the total opening area A surface SEM photograph was taken at a magnification of 200 times. The surface area of 600 μm ² , which was arbitrarily selected, was measured for the area of the hole and the hole diameter (diameter). Based on the results, the ratio (%) of the total open area to the total surface area and 5
The ratio (%) of the area of the opening having a pore diameter of not less than μm to the total opening area was determined.

Example 1 6.63 g of 3,4'-diaminophenyl ether and 3.56 g of p-phenylenediamine
Was dissolved in 290 g of NMP, and 13.37 g of terephthaloyl chloride was added thereto, followed by polymerization under a nitrogen stream for 4 hours. This was neutralized by adding 4.88 g of calcium hydroxide powder,
312 g of a para-type aromatic polyamide (PA) solution was obtained. Polyethersulfone (PES) is added to the obtained PA.
188 g of a 15% NMP solution of (Teijin Amoko Radel-300) was added to prepare a blend solution having a PA / PES ratio of 40:60.

The blend solution was cast on glass using a doctor blade knife having a spacing of 400 μm, dried in an oven at 130 ° C. for 15 minutes, cooled with cold water, and further boiled with boiling water for 1 hour. The film was fixed to a frame, dried at 150 ° C., and stretched 2.8 times using a contact heating type uniaxial stretching machine to obtain a film. This film is immersed in dichloromethane to extract only PES,
A porous film having a thickness of 15 μm was obtained.

The resulting porous film has an air permeability of 0.0
43 (sec / (100 ml * μm * cm ² )), the Gurley value is 0.645 sec, the Young's modulus is 40.9 and 4.6 Mpa for MD and TD, and the strength is 0.833 and 1.47 M, respectively.
The pa and elongation were 3.5 and 5.1%. The ratio of the total open area to the total surface area of this film is 40%,
In the case of this film, all the holes had a diameter of 5 μm or more. Therefore, for the total aperture area,
The area ratio of the opening having a pore diameter of 5 μm or more is 100%.
Met.

The porous film of the present invention thus obtained is excellent in liquid permeability and impregnation, and the one impregnated with epoxy resin has good adhesion to copper foil as a prepreg. there were.

Example 2 The ratio of PA to PES was 35:65
The blend solution obtained in the same manner except that
It was cast on glass using a doctor blade knife of 0 μm, dried in an oven at 130 ° C. for 15 minutes, cooled with cold water, and further boiled with boiling water for 1 hour. The film was fixed to a frame, dried at 150 ° C., and then subjected to sequential biaxial stretching of 1.7 × 1.7 times at a stretching temperature of 340 ° C. using a contact heating type stretching machine to obtain a film. The obtained film was immersed in dichloromethane to extract only PES to obtain a porous film having a thickness of 15 μm. The porosity of this porous film was 72%.

The air permeability of the film is 0.00 (sec / 10
0 ml * μm * cm ² ), and the Gurley value is 0.5 sec.
The Young's modulus was 11.1 and 13.23 Mpa, the strength was 0.363 and 0.363 Mpa, and the elongation was 9.47 and 5.5%, respectively, in MD and TD. The total area of the holes was 57% of the total surface area, and the area ratio of the holes having a hole diameter of 5 μm or more was 95%, and the area ratio of the holes having a diameter of 10 μm or more was 83%. The porous film thus obtained was excellent in liquid permeability and impregnation, and the film impregnated with the epoxy resin had good adhesion to copper foil as a prepreg.

[0031]

EFFECT OF THE INVENTION The aromatic polyamide porous film of the present invention has excellent material permeability, impregnating property and adhesiveness, has heat resistance and is suitable for use as a filter having good permeability, as well as a base material for prepreg. Can be used.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/03 610 H05K 1/03 610N // C08L 77:10 C08L 77:10 F-term (reference) 4D019 AA01 BA13 BB08 BC12 BD01 4F072 AB31 AD23 AL12 AL13 AL16 4F074 AA72 AA87 CB03 CB17 4F100 AB01B AK47A AK53 BA02 DG10A DH01A EH46 EH462 EJ37 EJ372 EJ86 EJ862 GB43 GB56 JD02A JL04 YY00A

Claims (8)

[Claims] 1. The following formula (1) — (OC—Ar ₁ —CO—NH—Ar ₂ —NH) — (1) (wherein, Ar ₁ and Ar ₂ each independently have a substituent. A porous aromatic polyamide having a repeating unit represented by the formula (1), wherein the total area of the pores present on the surface of the film is as follows: The total area of the surface is 30% or more of the total area of the surface (the total surface area), and the area of the opening having a pore diameter of 5 μm or more is 30% of the total area of the hole. And the air permeability of the film is 0 to 10 sec / (100 ml * μ
m * cm ² ) A para-type aromatic polyamide porous film. 2. The para-type aromatic polyamide, wherein at least 80 mol% of its repeating units are represented by the following formula (2)-(NH-A-NHCO-Ar-CO)-(2) An aromatic group represented by the formula (A),
Represents an aromatic group represented by the following formulas (A) and (B):
And (B) are aromatic groups having a ratio (A) / ((A) + (B)) of from 0.3 to 0.7, and these aromatic groups have some or all of their hydrogen atoms. It may be substituted with a halogen atom and / or an alkyl group having 1 to 6 carbon atoms. 2. The para-type aromatic polyamide porous film according to claim 1, which is a para-type aromatic polyamide represented by the formula: Embedded image 3. The para-type aromatic polyamide porous film according to claim 1, wherein an area of the apertures having a pore diameter of 10 μm or more is 40% or more of the total aperture area. . 4. An air permeability of 0 to 180 / (100 ml * μ
m * cm ² ), wherein the para-type aromatic polyamide porous film according to any one of claims 1 to 3. 5. The porosity of the porous film is 30 to 80%.
The para-type aromatic polyamide porous film according to any one of claims 1 to 4, wherein 6. A prepreg using the para-type aromatic polyamide porous film according to any one of claims 1 to 5. 7. A circuit board or a laminate using the para-type aromatic polyamide film according to claim 6. 8. A filter using the para-type aromatic polyamide porous film according to any one of claims 1 to 5.