JPH03143924A - Polyimide molding and its production - Google Patents

Abstract

PURPOSE:To obtain a colorless and transparent polyimide molding by molding an organic polar solvent solution of a specified polyimide precursor and imidizing the molding. CONSTITUTION:An organic polar solvent solution of a polyimide precursor of a logarithmic viscosity (as measured in N-methyl. 2-pyrrolidone in a concentration of 0.5 g/100ml) of 0.3-5.0 is obtained by dissolving 5-30wt.% polyamic acid based on at least one of repeating units of formulas I-IV (wherein X1 is formula V or -SO2-; X2 is any one of formulas VI-VIII; and X3 is formula IX or X) in an amide organic polar solvent of a b.p. <=170 deg.C (e.g. dimethylacetamide). A molding of a polyimide precursor, obtained by molding this solution, is through dehydration by slowly heating to 100-350 deg.C optionally in a vacuum or an inert gas atmosphere to imidize the polyamic acid into a polyimide molding based on at least one of repeating units of formulas XI-XIV.

Description

Detailed Description of the Invention The present invention is applicable to coatings such as liquid crystal alignment films and color filter protective films, molded products such as optical lenses, and electronic and electrical products containing films such as transparent conductive films. The present invention relates to a heat-resistant, colorless and transparent polyimide molded product, and a method for producing the same.

[Conventional technology and its problems]

Polyimide has traditionally been used as a coating material, a resin material with high heat resistance and excellent electrical and mechanical properties.
Many electronic products such as films and molded products.

Because of this, it could not be used for applications that require colorless transparency, such as optical applications.

The present invention was made in view of the above circumstances, and an object thereof is to provide a colorless and transparent polyimide molded article and a method for producing the same.

[Means to solve the problem]

In order to achieve the above object, the present invention provides the following general formula (
The first gist is a polyimide molded product containing at least one of the repeating units represented by I) or TV) as a main component, and a polyimide in which the following component (A) is dissolved in the following component (B). A step of preparing an organic polar solvent solution of a precursor, a step of preparing a solution of this polyimide precursor, a step of molding a molded body made of this polyimide precursor, and a step of molding the molded body made of this polyimide precursor immediately. The second gist is a method for manufacturing a polyimide molded body, which includes a step of converting the polyimide into a polyimide molded body.

(A) A polyamic acid containing at least one repeating unit represented by the following general formula (V) to (■) as a main component.

(Margin below) (B) Amide organic polar solvent.

[Effect]

That is, the present inventors conducted a series of studies on the causes of coloring of polyimide in order to obtain colorless and transparent polyimide. In the course of this research, we discovered that the combination of aromatic tetracarboxylic dianhydride and aromatic diamino compound, which are compounds used to synthesize polyimide, greatly affects coloration.

As a result of further research, we found that especially when 4,4-oxycyphthalic dianhydride (hereinafter abbreviated as rODPAJ) is combined with a specific aromatic diamino compound, A colorless and transparent polyimide molded body containing at least one repeating unit as a main component is obtained, and when producing this polyimide molded body, an amide-based organic polar such as dimethylacetamide (hereinafter abbreviated as rDMACJ) is particularly used as a solvent. The inventors have discovered that good results can be obtained by using a solvent and have arrived at this invention.

The colorless and transparent polyimide molded article of the present invention has the above-mentioned type (
1) It is constituted by a polyimide molded body containing at least one of the repeating units represented by (rV) as a main component. Such a colorless and transparent polyimide molded body is made of 0D expressed by the following formula (IX) as an acid dianhydride.
It is obtained by using PA and reacting it with at least one aromatic diamino compound selected from the aromatic diamino compounds represented by the following general formulas (X) to XIII). In addition, the following general formula (X) ~ (
The colorless and transparent polyimide molded bodies obtained using the method (Xllr) correspond to the above-mentioned types (1) to (IV), respectively.

HZ N -e-0-G-X l -e-08N HZ
... (X)Hz N -()-〇 -X t
-0-Q-N I(z...(XI))12! J
-()-Xz -()-NHz... (XII)H
EN<n-0-[]-NHz...(XI[) In the above -formats (X) to (X[[), X.

~X3 is the same as the polyimide represented by the above-mentioned format (1) to IV). The above aromatic diamino compounds may be used alone or in combination. In this case, in particular, in order to obtain a polyimide molded article with excellent transparency, among the above aromatic diamino compounds, compounds in which X2=co◎" in the general formula (XI) and those represented by the -form (Xll) are selected. Good results can be obtained by using

In this way, by combining the above-mentioned specific acid anhydride and an aromatic diamino compound, a colorless and transparent product containing one or at least two or more repeating units represented by the above-mentioned format (1) to IV) can be obtained. A polyimide molded body is obtained. Further, one of the above aromatic diamino compounds,
By making a polyamic acid from the above ○DPA and blending this with another polyamic acid obtained from the above aromatic cya≧no compound and the above 0DPA, the above-mentioned forms (1) to (TV) are carried out. It is also possible to obtain a colorless and transparent polyimide containing at least one of the repeating units shown as a main component. Here, the term "main component" is intended to include cases where the entire component consists only of the main component.

In this case, the greater the content of the repeating unit represented by the above format (1) or TV), which is the main component of the colorless and transparent polyimide molded product, the higher the colorless transparency of the resulting polyimide molded product. However, if at least one of the repeating units represented by the above general formulas (1) to IV) is contained in an amount of 70 mol% or more, at least the colorless transparency required in the present invention is ensured, so within that range, Aromatic tetracarboxylic dianhydrides other than the above-mentioned ○ DPA and other diamino compounds other than the above-mentioned aromatic diamino compounds can be used. However, the preferable range of the content of at least one of the repeating units represented by the above formats (1) to (■) is 70
It is mol% or more, and the most preferable range is 95 mol% or more.

Examples of the other aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride and 3.3'.

4.4'-benzophenone tetracarboxylic dianhydride,
Biphenyltetracarboxylic dianhydride, 44'-bis(
34-dicarboxyphenoxy)diphenylsulfone dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropanihydride, 2,3,6.
7-naphthalenetetracarboxylic dianhydride, 1,2,5
．． 6 Naphthalenetetracarboxylic dianhydride, 1.4゜5
．． Examples include 8-naphthalenetetracarboxylic dianhydride, which can be used alone or in combination.

In addition, other diamino compounds include 4゜4'-diaminodiphenyl ether, 4,4'diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, 4
, 4'-cyanobenzophenone, p-phenylenediamine, hendidine 3.3'-dimethyl hendidine, 44
'-Diaminodiphenylthioether, 3,3'-dimethoxy-4,4'-diaminodiphenylmethane, 3.3
'-dimethyl-4,4'-diaminodiphenylmethane,
Examples include 2,2-bis(1-(4-aminophenoxy)phenyl)hexafluoropropane, which can be used alone or in combination.

The colorless and transparent polyimide molded article of the present invention can be obtained, for example, as follows. By polymerizing 0DPA, which is the aromatic tetracarboxylic dianhydride, and the specific aromatic diamino compound in an amide-based organic polar solvent at a temperature of 80'C or less, the general formulas (V) to (■ )
A polyamic acid solution containing at least one of the repeating units represented by as a main component is prepared. Then, the excipients in the desired shape are placed in the air or in an inert gas using this boriaconic acid solution, and the organic polar solvent is removed by evaporation at a temperature of 50 to 350°C and normal pressure or reduced pressure. At the same time, it is obtained by dehydrating and ring-closing polyamic acid to form polyimide. It can also be obtained by a chemical idization method, such as by using a benzene solution of pyridine and acetic anhydride to remove the solvent and immediately dide the polyamic acid to form a polyimide.

As the above-mentioned organic polar solvent, an active organic polar solvent such as dimethylformamide, dimethylacetamide, etc. is preferably used. In particular, those having a boiling point of 170°C or lower, such as dimethylacetamide, are preferred. These organic polar solvents may be used alone or in combination of two or more. However, it is preferable to avoid using N-methyl-2-pyrrolidone as the organic polar solvent. The above-mentioned N-methyl-2-pyrrolidone is partially decomposed by the heating when the excipient of the boria succinic acid solution is heated, dehydrated and closed □ to form polyimide, and the decomposed product remains and becomes blackish brown. This is because there is a tendency for the resulting polyimide molded product to be colored yellowish brown. As organic polar solvents, each amide solvent such as dimethylacetamide listed above has a low boiling point, so
It volatilizes before being decomposed by the heating described above, and does not cause coloring of the polyimide molded article like N-methyl-2-pyrrolidone. However, as a polymerization catalyst, N-
After polyamic acid synthesis using methyl-2-pyrrolidone,
By dissolving the produced polyamic acid in the above-mentioned suitable solvent by solvent substitution, the above-mentioned adverse effects of N-methyl-2-pyrrolidone can be eliminated. In this case, the suitable solvent exemplified above is a diluting solvent. In producing the polyimide molded article, the polymerization solvent and the diluting solvent may be of different types, and the produced polyamic acid may be dissolved in the diluting solvent by solvent substitution.

In addition, when using the suitable organic polar solvents exemplified above, a poor or good solvent that does not impair transparency, such as ethanol, toluenebenzene, xylene, dioxane, tetrahydrofuran, or nitrobenzene, may be added to the solvent to improve solubility. One type or a mixture of two or more types may be used as appropriate within a range that does not cause any damage. However, if these solvents are used in large amounts, they will adversely affect the solubility of the polyamic acid produced. Therefore, it is appropriate to limit the amount used to less than 50% by weight of the total solvent, and most preferably to 30% by weight.

When producing a colorless and transparent polyimide molded article as described above, the logarithmic viscosity (intrinsic viscosity) of the polyamic acid solution is 0.
．． It is preferably in the range of 3 to 5.0. More preferred is 0.4 to 2.0. The above logarithmic viscosity is a value measured at a concentration of 0.5 g/100 ml in N-methyl-2-pyrrolidone. If the logarithmic viscosity is too low, the resulting polyimide molded article will have low mechanical strength, which is not preferable. On the other hand, if the logarithmic viscosity is too high, it is not preferable because it makes it difficult to cast the polyamic acid solution into an appropriate shape. Also, is it a boric acid? Yong? &
From the viewpoint of workability, etc., it is preferable to set the concentration to 5 to 30% by weight, preferably 15 to 25% by weight.

The logarithmic viscosity is calculated using the following formula, and the viscosity in the formula is measured using a capillary viscometer.

The shaping method using a polyamic acid solution varies depending on the shape of the desired molded object, but for example, when producing a polyimide film, the polyamic acid solution is applied to a mirror surface such as a glass plate or stainless steel plate to a certain thickness. The polyamic acid is imidized by casting and gradually heating at a temperature of 100 to 350°C to cause dehydration and ring closure.

In forming a film from a polyamic acid solution, the removal of the organic polar solvent and the heating for imidization of the polyamic acid may be performed continuously, or these steps may be performed under reduced pressure or in an inert gas atmosphere. good. moreover,
The properties of the resulting polyimide film can be improved by final heating to around 400°C for a short time. Another method for forming a polyimide film is to cast the above polyamic acid solution onto a glass plate, heat dry it at 100 to 150"C for 30 to 120 minutes to form a film, and then coat this film with pyridine. This is a method in which the film is made into a polyimide film by immersing it in a benzene solution of acetic anhydride or the like to perform solvent removal and imidization reaction, and a polyimide film can also be obtained by this method.

The polyimide film obtained in this way is colorless and transparent and is not colored yellow or yellowish brown as in conventional films, so it has extremely good transparency regardless of the film thickness.

Note that shaping using the above polyamic acid solution is not limited to the formation of a polyimide film as described above;
It can also be applied to the formation of molded objects such as plastic lenses, and in that case, the imidization of polyamic acid can be appropriately selected from either the above-mentioned thermal imidization or chemical imidization. .

When polyamic acid solution is imidized to form polyimide as described above, the resulting polyimide has a logarithmic viscosity (measured at 30'C at a concentration of 0.5 g/d1 in 97% sulfuric acid) from the viewpoint of properties. ) is preferably set within the range of 0.3 to 4.0. The most preferable value is 0.4 or more.

The polyimide molded product thus obtained is completely different from conventional molded products, and is colorless and transparent, and has extremely high transparency. In this invention, colorless and transparent refers to a polyimide film with a visible light (500 nm) transmittance of 70% or more and a yellowness index of -40 or less with respect to a polyimide film with a film thickness of 50 ± 5 μm. . The above transmittance is based on ASPM D 1003.
Yellowness can be measured according to JIS K 7103.

[Effect of the invention] As described above, the polyimide molded article of the present invention has a 0DPA
It is obtained by combining a specific aromatic diamine with a specific aromatic diamine, and it is not colored yellow or tan like conventional products, but is colorless and transparent, so it has extremely high transparency. In particular, when producing the above polyimide molded body,
If an amide-based organic polar solvent such as dimethylacetamide is used as a polyamic acid solution, the solvent will volatilize before it decomposes during heating when the polyamic acid is dehydrated and ring-closed to form polyimidation. For,
Unlike when N-methyl-2-pyrrolidone is used, the inconvenience that N-methyl-2-pyrrolidone decomposes due to heating during imidization and the resulting black-brown decomposition product colors the polyimide molded body does not occur at all, It becomes possible to produce completely colorless and transparent polyimide molded bodies. As described above, the polyimide molded product of the present invention is not colored and is colorless and transparent, so it can be used to form a thick liquid crystal alignment film, and can also be used as a protective film for color filters and for solar cells. Mousse film base material Polarizing film base material. It can be suitably used as a coating material for special aerospace components such as solar cells and thermal control systems, and in optical applications and coating materials that require heat resistance. It is also useful as a coating material for plastic lenses or lenses.

Next, examples will be described together with comparative examples.

[Examples 1 to 13, Comparative Example 122] The solvents shown in the table below and the diamino compound were placed in 12 separable flasks and mixed well at room temperature until the diamino compound was completely dissolved. In this case, the amount of the solvent used was set so that the monomer concentration of the diamino compound and the aromatic tetracarboxylic dianhydride shown in the table below was 20% by weight.

Next, the aromatic tetracarboxylic dianhydride shown in the same table was gradually added to the flask while suppressing the temperature rise due to heat generation. The reaction mixture was then stirred at room temperature for 4 hours to obtain a solution of polyamic acid having a logarithmic viscosity shown in the table below.

The polyamic acid solution obtained as described above was cast onto a glass plate to form a film, and this film was dried in a hot air dryer at 120°C for 60 minutes and then at 180'C for 60 minutes.
Then, a polyimide film with a thickness of 50 ± 5 μm was made by heating at 250 "C for 6 hours to imidize it. Furthermore, when the infrared absorption spectrum of the above polyimide film was measured, no absorption peculiar to amic acid was observed. , a characteristic absorption of the imide group was observed near 1780 cm-'.

Next, the yellowness index of the polyimide film obtained as described above was measured, and the transmittance in visible light (500 nm) was measured.
It is also shown in the table below.

In addition, in the table, BPDA is 3,4.3'4'-biphenyltetracarboxylic dianhydride, PMDA is pyromellitic anhydride, and BAPP is 2゜2-bis(4-(4-aminophenoxy)phenyl). Propane, BAPS is 4,
4'-bis(4-antanophenoxy) phenyl sulfone,
1. 34-BAPB is 1,3-bis(4-aminophenoxy)benzene, 1,4.4-BAPB is 1,4-bis(4-aminophenoxy)benzene, and BAPD is 4.
4'-bis(4-aminophenoxy)biphenyl, DD
P is 4,4'-diaminodiphenylpropane, DDF is 44'-diaminodiphenylpropane, 3.4-DDE
is 3.4-diaminodiphenyl ether, 3.3'-
For DDS, 3 is dimethylacetamide, DMF is dimethylformamide, and NMP is N methyl-2-pyrrolidone.

(Margins below) From the results in the table above, it can be seen that all of the polyimide films used as examples had a yellowness index of 40 or less, a transmittance of 70% or more, and were colorless and transparent films. On the other hand, since the polyimide film of Comparative Example 1 uses BPDA as the acid dianhydride, and the polyimide film of Comparative Example 2 uses NMP as the polymerization solvent, the yellowness index value is high and the transmittance is low.

Claims (2)

[Claims] (1) A colorless and transparent polyimide molded product characterized by containing at least one of the repeating units represented by the following general formulas (I) to (IV) as a main component. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(III) ▲Mathematical formulas , chemical formulas, tables, etc.▼...(IV) [In the above formulas (I) to (IV), X_1 is ▲mathematical formula,
There are chemical formulas, tables, etc. ▼, -SO_2-, and X_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, Furthermore, X_3 has ▲mathematical formulas, chemical formulas, tables, etc.▼,
▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] (2) A step of preparing an organic polar solvent solution of a polyimide precursor in which the following (A) component is dissolved in the following (B) component, and a polyimide precursor is obtained from this organic polar solvent solution of the polyimide precursor. 1. A method for producing a polyimide molded body, comprising the steps of molding the molded body and imidizing the molded body made of a polyimide precursor. (A) A polyamic acid containing at least one repeating unit represented by the following general formulas (V) to (VIII) as a main component. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(V) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(VI) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(VII) ▲Mathematical formulas , chemical formulas, tables, etc.▼...(VIII) [In the above formulas (V) to (VIII), X_1 is ▲mathematical formula,
There are chemical formulas, tables, etc. ▼, -SO_2-, and X_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, Furthermore, X_3 has ▲mathematical formulas, chemical formulas, tables, etc.▼,
▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] (B) Amide-based organic polar solvent.