JP5384286B2 - Polyimide and polyimide film comprising the same - Google Patents

Description

  The present invention relates to a polyimide containing an oxazole group and a polyimide film comprising the same.

  Conventionally, as polyimide film, it consists of polyimide consisting of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, or 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine. Polyimides are widely used, and electronic materials such as flexible printed wiring boards (hereinafter referred to as FPC) and base films for lead-on-chip (LOC) tapes in semiconductor devices, due to their excellent heat resistance and electrical insulation characteristics. (See Patent Document 1).

  Furthermore, since polyimide films are excellent in radiation resistance and cryogenic properties, they are often used for aircraft materials and space materials.

  Solvent-soluble and thermoplastic polyimide is used as the adhesive for the pseudo two-layer conductive laminate (CCL), but its Tg is about 240 to 250 ° C., and it is further improved without sacrificing copper foil adhesion. There is a need for improved heat resistance.

  However, heat resistance and thermoplasticity are in a trade-off relationship, and it is not easy to improve both at the same time. Furthermore, it has been pointed out that moisture absorbed in the polyimide adhesive has adverse effects such as swelling of the adhesive layer and poor adhesion during the solder reflow process.

JP-A-4-162491

  In the present invention, in order to solve these problems, attention is paid to polyimide introduced with a benzoxazole (BO) structural unit, which is expected to actively interact with copper foil, and has a high Tg (> 300 ° C.) and high heat. To try to develop a new heat-resistant material having plasticity, low water absorption and high adhesion to copper foil and non-thermoplastic PI film at the same time, and to provide a new heat-resistant adhesive for pseudo two-layer copper-clad laminate With the goal.

  In view of the above problems, as a result of intensive studies, it has been found that the above-described problems can be solved by the following configuration, and the present invention has been completed.

  That is, the present invention provides the following general formula (1):

The present invention relates to a polyimide using the diamine.

  A preferred embodiment relates to a polyimide film made of the above polyimide.

  According to the present invention, a polyimide and a polyimide film having characteristics of high toughness and high Tg and having a low linear expansion coefficient can be obtained by using a polyimide and a polyimide film having a diamine containing an oxozal group. .

  Embodiments of the present invention will be described in detail below, but these are examples of the embodiments of the present invention and the present invention is not limited to these contents.

  The polyimide film according to the present invention can be usually produced using polyamic acid as a precursor. Any known method can be used as a method for producing a polyamic acid. Usually, an aromatic acid dianhydride and an aromatic diamine are dissolved and reacted in an organic solvent so as to have a substantially equimolar amount, and a polyamide is obtained. It is produced by obtaining an acid organic solvent solution and stirring under controlled temperature conditions until the polymerization of the acid dianhydride and diamine is completed. These polyamic acid solutions are usually obtained at a concentration of 5 to 35% by weight, preferably 10 to 30% by weight, but a concentration within this range is preferable because an appropriate molecular weight and solution viscosity can be obtained.

  As the polymerization method of the polyamic acid, any known method and a combination thereof can be used. The characteristic of the polymerization method in the polymerization of the polyamic acid is in the order of addition of the monomers, and various physical properties of the polyimide film obtained can be controlled by controlling the monomer species and the order of addition.

In the present invention, any monomer addition method may be used for polyamic acid polymerization. The following method is mentioned as a typical polymerization method. That is,
1) A method in which an aromatic diamine is dissolved in an organic polar solvent and this is reacted with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride for polymerization.
2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Then, the method of superposing | polymerizing using an aromatic diamine compound so that an aromatic tetracarboxylic dianhydride and an aromatic diamine compound may become substantially equimolar in all the processes.
3) An aromatic tetracarboxylic dianhydride and an excess molar amount of the aromatic diamine compound are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to polymerize.
4) A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar.
5) A method of polymerizing by reacting a substantially equimolar mixture of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent.
And so on. These methods may be used singly or in combination.

  Suitable acid anhydrides that can be used in the present invention are not particularly limited, but pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl Tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4 ′ -Benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4- Dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2 , 3-Zika Boxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylenebis (trimerit Acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride), 1,4-hydroquinone dibenzoate-3.3 ', 4,4′-tetracarboxylic dianhydride, 2,5-dimethyl-1,4-hydroquinone dibenzoate-3.3 ′, 4,4′-tetracarboxylic dianhydride, 2,5-dichloro 1,4-hydroquinone dibenzoate-3.3 ′, 4,4′-tetracarboxylic dianhydride, 2-chloro-1,4-hydroquinone dibenzoate .3 ', 4,4'-tetracarboxylic dianhydride and include analogs thereof, singly or in any may be preferably used mixed mixture ratio.

  Next, as the diamine used in the present invention, the general formula (1):

Is required. Other suitable diamines that can be used are not particularly limited, but include 4,4′-oxydianiline, p-phenylenediamine, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, benzidine, 3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3 , 4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diamino Diphenyl N-methylamine, , 4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene, 1,2-diaminobenzene, 2,2-bis (4- (4-amino And phenoxy) phenyl) propane and the like, and the like, and a mixture of these alone or in an arbitrary ratio can be preferably used.

  These diamines and acid dianhydrides can be appropriately combined to design a molecule to obtain a polyimide having desired characteristics.

In this molecular design, there is no perfect rule, and molecular design within the common sense of those skilled in the art is required according to the following general tendency.
(I) When a monomer having a rigid structure such as phenylenediamines, benzidines, pyromellitic dianhydride is used, the elastic modulus tends to increase and the linear expansion coefficient tends to decrease.
(II) When a monomer having a flexible group such as an ether bond, a hydrocarbon group, a sulfone group, or a carbonyl group is used in the molecular chain, the elastic modulus tends to decrease and the linear expansion coefficient tends to increase.
(III) The same tendency as in (II) occurs when a non-linear monomer is used when viewed as a whole molecule, such as 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  As a preferred solvent for synthesizing a polyimide precursor (hereinafter, also referred to as polyamic acid), any solvent that dissolves polyamic acid can be used, but an amide solvent, that is, N, N-dimethylformamide. N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  In addition, a filler can be added for the purpose of improving various film properties such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. The filler is not particularly limited, and preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

  In the polymerization of polyamic acid, the weight average molecular weight of the polyamic acid is preferably 150,000 or more, and more preferably 200,000 or more. This is because when the weight average molecular weight is 150,000 or less, a polyimide film having poor strength can be obtained.

  In order to obtain the polyimide film of the present invention from this polyamic acid solution, either (1) a thermal method of dehydrating and imidizing thermally or (2) a chemical method using a dehydrating agent may be used. It is more preferable to use a chemical method that facilitates obtaining a film having excellent mechanical properties such as strength and strength.

  Below, the method of manufacturing a film from a polyamic acid solution is illustrated. (1) The polyamic acid solution is cast or coated on a drum or endless belt to form a film, and the film is dried at a temperature of 150 ° C. or lower for about 5 to 60 minutes until it has self-supporting properties. Next, it is peeled off from the support and the end is fixed, and then dried and imidized by gradually heating to about 100 ° C. to 500 ° C. while limiting the shrinkage of the membrane. An inventive polyimide film is obtained.

  In the above production method, a mixed solution in which a release agent is added to the polyamic acid solution may be used instead of the polyamic acid solution in order to make the film having self-supporting property easy to peel off from the support. When a polyimide film is obtained by a chemical method, a mixed solution in which a dehydrating agent of a stoichiometric amount or more and a catalytic amount of tertiary amines are added to the polyamic acid solution may be used instead of the polyamic acid solution.

  Examples of the release agent herein include aliphatic ethers such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether, tertiary amines such as pyridine and picoline, triphenyl phosphine, and triphenyl phosphate. And organic phosphorus compounds such as

  Examples of the dehydrating agent include aliphatic or aromatic acid anhydrides such as acetic anhydride and phthalic anhydride. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, and heterocyclic tertiary amines such as pyridine, picoline and isoquinoline.

  Furthermore, the film may be stretched when the film is dried or imidized. This is because a film having excellent mechanical properties can be easily obtained by stretching.

  In addition, for the purpose of improving various properties such as adhesiveness, heat resistance, or slipperiness in the film, the film may contain fine particles such as titanium oxide, calcium carbonate, alumina, silica gel, A surface modifier such as a silane coupling agent or a solution containing fine particles and a binder resin may be applied, or a discharge treatment such as a corona treatment or a plasma treatment may be performed.

(Experiment)
BO-containing diamine (OBABO) was synthesized from 4,4′-Oxybisbenzoic Acid and 2-Amino-5-nitrophenol, purified by recrystallization. After thoroughly dissolving the well-dried diamine in the dehydrated solvent (DMAc or NMP), gradually add an equimolar amount of tetracarboxylic dianhydride powder and stir for 24 hours or more at room temperature to give a viscous polyamic acid. A (PAA) solution was obtained. The intrinsic viscosity of the PAA solution was 0.5 wt% and was determined at 30 ° C. using an Ostwald viscometer. The PAA solution was cast on a glass substrate, dried at 80 ° C./2 h, and then thermally imidized at a predetermined temperature. Further, in order to remove the residual strain, the substrate was peeled off and subjected to heat treatment at a predetermined humidity. The obtained PI film was evaluated for glass transition temperature (Tg), linear thermal expansion coefficient (CTE), 5% thermal weight loss temperature (Td5), and the like. Moreover, the PAA solution was cast on the M surface of the copper foil (Furukawa Electric F3-WS thickness: 18 μm), and thermal imidization was performed to prepare a two-layer copper-clad laminate, and the copper foil peel strength was evaluated.

  (Example 1 and Comparative Example 1)

  Example 1

Linear expansion coefficient 20ppm / K
Tg 365 ° C
Maximum breaking elongation 25.5%

  (Comparative Example 1)

Linear expansion coefficient 65ppm / K
Tg 355 ° C
Maximum breaking elongation 12.0%

  (Example 2 and Comparative Example 2)

  (Example 2)

Linear expansion coefficient 33ppm / K
Tg 281 ° C
Maximum breaking elongation 60.6%

  (Comparative Example 2)

Linear expansion coefficient 50ppm / K
Tg 254 ° C
Maximum elongation at break 50.0%

  (Example 3 and Comparative Example 3)

  (Example 3)

Linear expansion coefficient 25ppm / K
Tg 333 ° C
Maximum elongation at break 69.4%

  (Comparative Example 3)

Linear expansion coefficient 43ppm / K
Tg 358 ° C

(Results and discussion)
Table 1 shows the results obtained using pyromellitic dianhydride (PMDA) with tetracarboxylic dianhydride as a component.

  PMDA / OBABO PI showed a high Tg of 300 ° C. or higher, although slightly lower than PMDAA, 4,4′-ODA. The PMDA / OBABO system unexpectedly showed a low CTE (24.6 ppm / K) even though it contained an ether bond. This is probably due to the rigid structure of BO. In addition, as shown in FIG. 2, in the dynamic viscoelasticity curve, when the Tg was exceeded, a sharper decrease in storage elastic modulus was observed, and it was also confirmed that it was thermoplastic. The peel strength is 0.83 kgf · cm, which is 1 of PMDA / 4,4′-DDA system. Although it did not reach Okgf · cm, the copper foil adhesion was relatively good.

Claims (2)

The following general formula (1):

Polyimide obtained by reacting diamine and acid dianhydride .   A polyimide film comprising the polyimide according to claim 1.