JPS6327579A - Pressure-sensitive transparent adhesive material - Google Patents

Abstract

PURPOSE:To obtain the titled material outstanding in both optical properties and heat resistance, by forming silicone-based adhesive layer(s) on a colorless and clear polyimide formed body produced from each specific acid and diamine components. CONSTITUTION:The objective material can be obtained by forming silicone-based adhesive layers on at least one surface of the substrate consisting of a coloress and clear polyimide formed body constituted mainly of an unit selected from recurring units of respective formulae I-IV [X1 is O, S, etc.; X2 is SO2, C(CH3)2, etc.; X3-X4 are each H, F, etc.]. Said polyimide formed body can be prepared by polymerization at <=80 deg.C in an organic polar solvent between a biphenyl tetracarboxylic acid dianhydride such as 3,3'-4,4'-biphenyl tetracarboxylic dianhydride and a diamine compound such as 2,4-toluenediamine followed by simultaneous desolvation and imidization of the formed body made of the resulting polyamic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-sensitive transparent adhesive material that is excellent in both heat resistance and optical properties.

[Conventional technology]

BACKGROUND ART Pressure-sensitive adhesive materials, such as pressure-sensitive adhesive tapes, are constructed by providing an adhesive layer on a sheet-like substrate (support tape), and are used in every field of daily life and industry. This type of pressure-sensitive adhesive material uses cellulose film, polyester film, etc. as a support tape in fields where optical properties, that is, transparency are required.
Cellophane tape or polyester tape with an adhesive layer is used for this purpose. Furthermore, in fields where heat resistance is required, for example in the field of electrical insulation, polyimide adhesive tapes are used, which are made by forming a silicone adhesive layer on a polyimide film with high heat resistance.

[Problem that the invention seeks to solve]

Pressure-sensitive adhesive materials used in fields where the above-mentioned optical properties are required have a support such as a cellulose film, are colorless and transparent, and have excellent optical properties. However, it has the disadvantage of poor heat resistance. Furthermore, the support of pressure-sensitive adhesive materials used in fields where heat resistance is required is a polyimide film, and although the polyimide film is transparent, it is colored reddish-brown and has poor optical properties.

Therefore, as mentioned above, it is used only in fields where heat resistance is required. However, recently, pressure-sensitive adhesive materials have been required to be used in fields where both heat resistance and optical properties are required.For example, there are applications such as solar cell protective films for space use. however,
The reality is that there are no conventional pressure-sensitive adhesive materials that are excellent in both heat resistance and optical properties, and there is a strong demand for the development of such materials.

' This invention was made in view of the above circumstances, and its purpose is to provide a pressure-sensitive transparent adhesive material that is excellent in both heat resistance and optical properties.

[Means for solving problems]

In order to achieve the above object, the pressure-sensitive transparent adhesive material of the present invention has a repeating unit represented by the following general formula (1), a repeating unit represented by the general formula (■), and a repeating unit represented by the general formula (III). A colorless and transparent polyimide molded body containing at least one repeating unit selected from the group consisting of the repeating unit represented by the formula (rV) and the repeating unit represented by the general formula (rV);
A structure is adopted in which a silicone adhesive layer is formed on at least one surface of this molded body.

(The following is a blank space) That is, the present inventors have repeatedly conducted research focusing on acid component raw materials and diamine component raw materials, which are the constituent components of polyimide, in order to make polyimide molded products such as polyimide films colorless and transparent. It was discovered that a colorless and transparent polyimide can be obtained by using an acid component raw material and a specific diamine component raw material, and when this is combined with a silicone adhesive layer, a pressure-sensitive polyimide with excellent not only heat resistance but also optical properties can be obtained. The present invention was achieved by discovering that a transparent adhesive material can be obtained.

The colorless and transparent polyimide used in this invention is selected from, for example, biphenyltetracarboxylic dianhydride represented by the general formula (V) and aromatic diamino compounds represented by the following general formulas 1) to IX). and at least one diamino compound.

HtNtX l? NHz...(VI) The above biphenyltetracarboxylic dianhydride includes the following 3.
Examples include 3', 4.4°-biphenyltetracarboxylic dianhydride and 2.3.3', 4°-biphenyltetracarboxylic dianhydride υ.

Further, among the aromatic diamino compounds having an amino group at the meta position, representative examples of the aromatic trinuclear sia and amine represented by the general formula (Vl) include the following.

3.3゛-diaminodiphenyl ether3.3゛-
Diaminodiphenylsulfone 3.3° -Diaminodiphenylthioether 3.3’ -Diaminodiphenylmethane 3.3° -Diaminobenzophenone Representative examples of aromatic tetranuclear diamines represented by the above general formula (■) include the following: Things can be given.

4.4'-bis(3-aminophenoxy)diphenylsulfone CI.

4.4'-Bis(3-aminophenoxy)diphenylpropane 4.4°-Bis(3-aminophenoxy)diphenylhexafluoropropane Representative example of aromatic-nuclear diamine represented by the above general formula (■) Examples include the following:

Ht N t NHz Metaphenylenediamine (blank space) 2.4-)luenediamine 4.6-dimethylmethphenylenediamine 2.6-diamitumesitylene 4-chlormethphenylenediamine (blank below) 3.5-diaminobenzoic Acid 5-Nitrometaphenylenediamine Representative examples of the aromatic trinuclear diamine represented by the above general formula (IX) include the following.

1.4-bis(3-aminophenoxy)benzene H2N
-o-070? NH2 1,3-bis(3-aminophenoxy)benzene Aromatic dinuclear diamine, aromatic dinuclear diamine, aromatic -
The nuclear diamine and the aromatic trinuclear diamine may be used alone or in appropriate combinations.

Only by combining the above-mentioned biphenyltetracarboxylic dianhydride and the above-mentioned aromatic diamine having an amino group at the meta position, one type of repeating unit represented by the above general formula (1) to IV) can be produced. Alternatively, a colorless and transparent polyimide containing two or more types as main components can be obtained. 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 general formula (rV), which is the main component of the colorless and transparent polyimide, the more colorless and transparent the resulting polyimide becomes. However, the general formula (1) or rV
) at least one of the repeating units represented by 70 mol%
If the content is above, at least the colorless transparency required in the present invention is ensured, and within this range, other aromatic tetracarboxylic dianhydrides other than the above-mentioned biphenyltetracarboxylic dianhydride and the above-mentioned metals can be used. Other diamino compounds other than aromatic diamines having an amino group in position can be used.

However, the preferred range of the content of at least one repeating unit represented by the above general formula (1) to IV) is 7
It is 0 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゛-benzophenonetetracarboxylic dianhydride, 4.4°-oxycyphthalic dianhydride, 4゜4°
-bis(3,4-dicarboxyphenoxy)diphenylsulfonic anhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoroproxyanhydride, 2,3
, 6.7-naphthalenetetracarboxylic dianhydride, 1,
2.5.6-Naphthalenetetracarboxylic dianhydride, 1
．． Examples include 4,5°8-naphthalenetetracarboxylic dianhydride, which can be used alone or in combination.

Other diamino compounds include 4°4°-diaminodiphenyl ether, 3.4'-diaminodiphenyl ether, 4.4'-diaminodiphenyl sulfone, 4.4"-diaminodiphenylmethane, and 4.4'-diaminodiphenyl ether.
4'-diaminobenzophenone, 4.4'-diaminodiphenylpropane, paraphenylenediamine,
Benzidine, 3.3'-dimethylbenzidine, 4.
4°-diaminodiphenylthioether, 3.3°
-dimethoxy-4゜4''-diaminodiphenylmethane,
3,3゛-dimethyl-4,4°-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, etc. These can be used alone or in combination.

The colorless and transparent polyimide molded article used in this invention is prepared by polymerizing the above-mentioned aromatic tetracarboxylic dianhydride and diamino compound in an organic polar solvent at a temperature of 80°C or lower to prepare a polyamic acid solution. A molded body of a desired shape is formed using a solution, and this molded body is placed in air or an inert gas at a temperature of 5.
It can be obtained by evaporating and removing the organic polar solvent under conditions of 0 to 350[deg.] C. and normal pressure or reduced pressure, and simultaneously dehydrating and ring-closing the polyamic acid to form a polyimide. Also,
It can also be obtained by a chemical imidization method, such as by removing the solvent and imidizing the above polyamic acid using a benzene solution of pyridine and acetic anhydride to form a polyimide.

As the above organic polar solvent, amide organic polar solvents such as N,N-dimethylformamide and N,N-dimethylacetamide are suitable. Particularly preferred are those having a boiling point of 170°C or lower, such as N,N-dimethylacetamide. These organic polar solvents may be used alone or in combination with
There is no problem in using a mixture of more than one species. However, it is preferable to avoid using N-methyl-2-pyrrolidone as the organic polar solvent. N-Methyl-2-pyrrolidone is partially decomposed by heating the excipient of the polyamic acid solution and dehydrated and ring-closed to form polyimidation, and the decomposed product remains and becomes blackish brown. This is because there is a tendency to color the sheet-like substrate made of polyimide yellowish brown. As organic polar solvents, the above-mentioned N,N-dimethylacetamide and other solvents have low boiling points, so they volatilize before being decomposed by the heating described above, resulting in colorless solvents like N-methyl-2-pyrrolidone. Does not cause coloring of transparent polyimide molded bodies. However, if N-methyl-2-pyrrolidone is used as a polymerization solvent and the resulting polyamic acid is dissolved in a suitable solvent as exemplified above by solvent substitution after polyamic acid synthesis, N-methyl-2-pyrrolidone can be The above disadvantages 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 solvent exemplified above, a poor solvent or a good solvent that does not impair transparency, such as ethanol, toluene, benzene, xylene, dioxane, tetrahydrofuran, nitrohenzene, etc., is added to the solvent.
One type or two or more types may be appropriately mixed and used within a range that does not impair solubility. 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 intrinsic viscosity of the polyamic acid solution is preferably in the range of 0.3 to 5.0. More suitable is 0.4-2
．． It is 0. The above intrinsic viscosity is a value measured at a concentration of 0.5 g/100 mj+ in N-methyl-2-pyrrolidone. If the intrinsic viscosity is too low, the resulting colorless and transparent polyimide molded product will have low mechanical strength, which is not preferable.

Further, if the intrinsic viscosity is too high, it is not preferable because it becomes difficult to cast the polyamic acid solution into an appropriate shape. In addition, the concentration of the polyamic acid solution is also 5 to 30% by weight, preferably 15 to 30% by weight, from the viewpoint of workability etc.
It is preferable to set the content to 25% by weight.

The above-mentioned intrinsic viscosity is calculated by the following formula, and the viscosity in the formula is measured by a capillary viscometer.

It is known that this intrinsic viscosity is directly related to the molecular weight of the polymer.

The shaping method using a polyamic acid solution varies depending on the shape of the desired molded product, but for example, when obtaining a polyimide film, the polyamic acid solution is applied to a mirror surface of a glass plate, stainless steel plate, etc. to a certain thickness. spread to become
The polyamic acid is imidized by gradually heating at a temperature of 100 to 356° 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. Furthermore, the properties of the resulting polyimide film can be improved by finally heating it 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, etc.
A film is formed by heating and drying at 50°C for 30 to 120 minutes, and this film is immersed in a benzene solution of pyridine and acetic anhydride to remove the solvent and undergo an imidization reaction, thereby converting the film into a polyimide film. , a polyimide film can also be obtained by this method.

The polyimide film thus obtained is colorless and transparent and is not colored yellow or yellowish brown as in conventional films, so it has extremely good transparency even if it is a thick film.

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 bodies in shapes other than film shapes such as plate shapes, and in that case, the imidization of polyamic acid can be appropriately selected from either the above-mentioned thermal imidization or chemical imidization. This is Shiuruchino.

When polyamic acid solution is imidized to form polyimide as described above, the produced polyimide has an intrinsic 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 obtained in this way is completely different from conventional products in that it is colorless and transparent and has extremely high transparency. In this invention, colorless and transparent means a film thickness of 50 ± 5 μm. The visible light (500 nm) transmittance for the polyimide film is 70% or more, the yellowness index is 40 or less, and the whiteness (W
(Lab)) is 70 or more. The above transmittance can be measured according to ASPM D 1003'', and the yellowness can be measured according to JIS K 7103. Particularly excellent transparency is shown by general formulas (Vl) and (■). This is an aromatic trinuclear diamine and an aromatic trinuclear diamine in which X and X2 are SO□.The polyimide molded product obtained using this product is extremely transparent. Not only is it excellent, but it also has extremely good heat resistance.

The refractive index of such a polyimide molded body is 1.6 or more, which is higher than other transparent films.

The shape of the polyimide molded product is usually film-like or plate-like, but in some cases it may be cylindrical or plate-like.
It may have a three-dimensional shape such as a prismatic shape.

The pressure-sensitive transparent adhesive material of the present invention is obtained by using the above colorless transparent polyimide molded body as a support and forming a silicone adhesive layer on at least one surface of the support. Since the colorless and transparent polyimide molded article is usually in the form of a film, a silicone adhesive layer is formed on its lower side, and the silicone adhesive layer is used to adhere it to a desired location. However, it is also used for applications such as forming a silicone adhesive layer on both sides of a colorless transparent polyimide molding, sandwiching this between two types of transparent members, and joining two types of transparent members. In that case, silicone adhesive layers are formed on both sides of the colorless and transparent polyimide molded body.

The silicone adhesive constituting the silicone adhesive layer may be a conventionally known one, for example, a molar ratio of 5i02 units to (CI,)*5iO0,, units of 1:0°4.
~1:1 copolymer 30 to 70 parts by weight and dimethylpolysiloxane raw rubber 70 to 30 parts by weight, or this zincyl polysiloxane raw rubber partially containing phenyl groups is used. Commercially available products include KR120 manufactured by Shin-Etsu Chemical Co., Ltd. and 5) 1-4280 manufactured by Toray Silicon Co., Ltd.

The silicone adhesive layer is formed by coating the colorless transparent polyimide molded body with a coating liquid of a silicone adhesive dissolved in various organic solvents by an appropriate method.

In order to easily form this adhesive layer, it is preferable to add a curing catalyst such as benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, etc. to the coating solution.

In addition, for the purpose of improving the anchoring ability of the adhesive layer to the colorless transparent polyimide molded body, it is preferable to perform the following treatment. That is, in general, the surface of the colorless transparent polyimide molded body on which the adhesive layer is provided is physically roughened using sputtering or the like, or chemically activated, and then the adhesive is applied. method is done. However, in order to obtain a particularly large anchoring force, it is effective to perform the treatment disclosed in Japanese Patent Publication No. 50-29851. That is, SiO
□ unit and JSiOo,, unit (R is a methyl group.

Ethyl group, trifluoropropyl group, phenyl group.

A copolymer (A) having a molar ratio of t:O, 4 to 1:1 with a substituted or unsubstituted-valent hydrocarbon group such as a vinyl group is prepared, and R2'SiO units (R' is (monovalent hydrocarbon group selected from the same organic groups), and has a viscosity of 10,000 cps (25°C) or more, and has a hydroxyl group or a vinyl group at the end of the molecular chain. . And the above A component 3
By partially condensing 0 to 70 parts by weight of component B with 70 to 30 parts by weight, 0.2 to 10 mol% of all organic groups are phenyl groups and 0.005 to 5 mol% of vinyl groups. Therefore, it is effective to form a treated layer of organopolysiloxane (C) whose remainder mainly consists of methyl groups on the surface of the colorless transparent polyimide molded body (support).

As a result, a large anchoring effect can be obtained, and the silicone adhesive layer can be firmly formed on the support surface. Note that, prior to forming the treated layer of organopolysiloxane as described above, it is desirable to previously perform the above-mentioned conventional surface treatment on the surface of the support.

Further, it is advantageous to dilute the organopolysiloxane with an organic solvent such as benzene, toluene, xylene, trichlorethylene, perchlorethylene, etc., as this makes it easier to carry out heavy work on the support. In order to ensure that the organopolysiloxane is completely cured after application, benzoyl peroxide, dicumyl peroxide, and diperoxide are also treated with a catalyst such as monobutyl, as in the case of the silicone adhesive. It is preferable to add 0.5 to 10% by weight.

The coating amount of the organopolysiloxane as described above is 0.02 g/m or more, particularly 0.2 g/m to the support.
It is also preferable to set the coating amount of the silicone adhesive to the organopolysiloxane in a range of 1:0.005 to 1:1, preferably 1:0.005 to 1:0.5.

The pressure-sensitive transparent adhesive material treated with organopolysiloxane in this way can be used as a support for the silicone adhesive layer because the organopolysiloxane has an excellent primary effect on the silicone adhesive layer. It has an excellent anchoring property, and therefore has the excellent feature of not causing so-called adhesive peeling, and also has the advantage of exhibiting extremely strong adhesion to surfaces made of various materials.

The pressure-sensitive adhesive material of the present invention obtained as described above has the same heat resistance as that of conventional polyimide adhesive tapes, and also has transparency comparable to conventional polyester adhesive tapes, cellophane tapes, etc. ing. Therefore, it can be applied to applications that require both heat resistance and transparency, or applications where new functions can be obtained by adding transparency. Examples of these uses include, for example, protection of space solar cells, FPC surface protection, printed labels on high-temperature members, electrical insulation materials, and the like.

〔Effect of the invention〕

As described above, the pressure-sensitive transparent adhesive material of the present invention has a silicone adhesive layer on a colorless transparent polyimide molded body whose main component is a special repeating unit derived from a specific acid component raw material and a specific diamine component raw material. Because it is constructed with a There is.

Next, examples will be described together with comparative examples.

[Example 1-to, Comparative Examples 1 to 3] A solvent shown in Table 1 below and a diamino compound were placed in a No. 11 separable flask and stirred well at room temperature until the diamino compound was completely dissolved. At this time, the amount of the solvent used was such that the concentration of the diamino compound and the aromatic tetracarboxylic dianhydride shown in Table 1 below was 20% by weight.

Subsequently, the aromatic tetracarboxylic dianhydride shown in the same table was gradually added to the homogeneous flask while suppressing the temperature rise due to heat generation. The reaction was then stirred at room temperature for 4 hours, and the intrinsic viscosity (η
A solution of polyamic acid having 1 nh) was obtained.

“The viscous solution of polyamic acid obtained as described above was cast onto a glass plate to form a film, which was dried in a hot air circulation dryer at 120°C for 60 minutes and then at 180°C for 60 minutes.
A polyimide film having a thickness of 50±5 μm was produced by heating for 0 minutes and then at 250° C. for 6 hours to convert it into polyimide. When the infrared absorption spectrum of this film was measured, no absorption specific to amic acid was observed, but characteristic absorption of imide groups was observed around 1780 cm-'.

Next, regarding the polyimide film obtained as described above, Yl (yellowness index: yellowness)
, W (Lab: whiteness) and transmittance in visible light (500 nm) were measured, and the results are shown in Table 1. In addition, in Table 1, 5-BPDA is 3.3'
, 4.4'-biphenyltetracarboxylic dianhydride, a-BPDA is 2,3.3', 4'-biphenyltetracarboxylic dianhydride, PMDA is pyromellitic dianhydride, 3.3°- DDS is 3.3′-diaminodiphenylsulfone, 3.3°-DDE is 3.3′-
Diaminodiphenyl ether, 3,3°-DDM is 3
．． 3′-diaminodiphenylmethane, 3.3′-DSP
is 3.3°-diaminodiphenylthioether, 3.
3'-BAPS is 4.4°-bis(3-aminophenoxy)diphenylsulfone, 3.3''-BAPR is 2.
2-bis(4-(3-aminophenoxy)phenyl)propane, 3.3'-BAPF is 2,2''-bis(4-(
3-aminophenoxy)phenyl]hexafluoropropane, 4.4'-BAPP is 2,2'-bis[4-
(4-aminophenoxy)phenyl]propane, DMA
c is dimethylacetamide, and DMF is N.

N-dimethylformamide, NMP is N-methyl-2-
Indicates pyrrolidone.

(Hereinafter, blank space) Next, among the films obtained in Examples 1 to 10 above, Example 1. Example 2. One side of the film obtained in Example 5 was coated with the coating solution (■) shown below, and dried to a coating density of 4 g/m.
A treated layer was formed, and then a coating solution (3) shown below was applied thereon to form an adhesive layer having a thickness of 0.03 to 0.04 mm. As a result, polyimide adhesive tapes having the properties shown in Table 2 were obtained.

Coating liquid 1: 50 parts by weight (hereinafter abbreviated as "parts") of a siloxane resin consisting of R: +5iO0, units and SiO□ units (molar ratio 0.7:1) and a raw rubber-like organopolymer represented by the unit formula RzSiO. 100 parts xylene solution of 60% by weight organopolysiloxane, obtained by condensation reaction with 50 parts of siloxane, in which 5 mol% of all organic groups are phenyl groups, 0.3 mol% are vinyl groups, and the remainder are methyl groups. , 1.2 parts of bunzoyl peroxide and 200 parts of toluene.

Coating liquid ■: A mixed solution consisting of 100 parts of KR120 (silicone adhesive composition) manufactured by Shin-Etsu Chemical Co., Ltd., 1.2 parts of benzoyl peroxide, and 100 parts of toluene.

(Margin below) Note that the yellowness index, whiteness, and transmittance of the polyimide adhesive tape obtained using the films of Examples 1 and 2.5 were not significantly different from those of the polyimide film used as the support. .

Thus, according to the examples, it can be seen that a pressure-sensitive transparent adhesive material having excellent properties as an adhesive material, as well as excellent heat resistance and optical properties, can be obtained.

Claims (1)

[Claims] (1) A repeating unit represented by general formula (I), a repeating unit represented by general formula (II), a repeating unit represented by general formula (III), and a repeating unit represented by general formula (IV) below. A pressure-sensitive transparent adhesive material comprising: a colorless transparent polyimide molded body containing at least one repeating unit selected from the group consisting of repeating units as a main component; and a silicone adhesive layer formed on at least one surface of the molded body. ▲There are mathematical formulas, chemical formulas, tables, etc.▼…(I) [In formula (I), X_1 is O, S, SO_2, C
H_2, CF_2, C(CH_3)_2, C(CF_3
)_2 or CO. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼…(II) [In formula (II), X_2 is SO_2, C(CH_3
)_2 or C(CF_3)_2. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(III) [In formula (III), X_3 to X_6 are H, F, Cl
, CH_3, C_2H_5, NO_2, or CF_3, and may be the same or different. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼…(IV)