JPH0656936A - Crosslinkable fluoropolymer composition and method of its crosslinking - Google Patents

Abstract

PURPOSE:To obtain this compsn. which gives a crosslinked article low in dielectric properties and surface energy and excellent in chemical resistance, nonstickiness, and weatherability by mixing a polymer having fluorinated alicyclic structures and maleimide groups in molecule with a polymer having fluorinated alicyclic structures and amino groups in the molecule. CONSTITUTION:The compsn. is prepd. by mixing a polymer having fluorinated alicyclic structures and maleimide groups of the formula in the molecule with a polymer having fluorinated alicyclic structures and -NH2 groups in the molecule. Both the polymers are sol. in specific fluorinated solvents. Though they are miscible with each other at any ratio, a mixing ratio by wt. of (30:70)-(70:30) is pref. in terms of the properties of the compsn. after thermally crosslinked.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a crosslinkable fluoropolymer composition and a method for crosslinking the same.

[0002]

2. Description of the Related Art Fluorine resins are excellent in chemical resistance, low dielectric property, low surface energy, non-adhesiveness, weather resistance and the like, and are therefore used in various applications where general-purpose plastics cannot be used.

CF in JP-A-1-13125
₂ = CFO (CF ₂ ) _n CF = CF ₂ is known to give a polymer having a low refractive index and a low dielectric constant, which is soluble in a solvent because it has a cyclic structure by cyclopolymerization. However, since the polymer having a glass transition point of n = 1 is 69 ° C., and the polymer having a glass transition point of n = 2 is 108 ° C., the heat distortion temperature is not so high that it is insufficient for use at high temperature. There was a problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of a polymer having a fluorine-containing alicyclic structure, and has chemical resistance, low dielectric property, low surface energy, non-adhesiveness, and weather resistance. It is an object of the present invention to newly provide a composition which gives a crosslinked product having an improved heat distortion temperature which can withstand high temperature use while maintaining properties and the like.

[0005]

Means for Solving the Problems The present inventor has conducted diligent studies to achieve the object based on the recognition of the above problems, and as a result, has a fluorine-containing alicyclic structure and has a general formula in its molecule. The above-mentioned problems are solved by heating a composition composed of a polymer having a maleimide group represented by (1) and a polymer having a fluorine-containing alicyclic structure and having a —NH ₂ group in its molecule to crosslink by heating. It was found that the obtained crosslinked product was obtained. Further, it was also found that the composition containing these two kinds of polymers did not generate a foaming group in the molded product, because a leaving group was not generated along with the crosslinking reaction.

[Chemical 3]

That is, the present invention provides a polymer having a fluorine-containing alicyclic structure and having a maleimide group represented by the general formula (1) in its molecule (hereinafter referred to as maleimide group-containing fluorine-containing polymer), A polymer having a fluorine-containing alicyclic structure and having an —NH ₂ group in its molecule (hereinafter referred to as an amino group-containing fluorine-containing polymer), and a crosslinkable fluorine-containing polymer composition containing these two polymers Object, and further 10 parts of this composition
The present invention provides a cross-linking method characterized by performing heat cross-linking in a temperature range of 0 to 300 ° C.

[Chemical 4]

The maleimide group-containing fluoropolymer and amino group-containing fluoropolymer of the present invention are synthesized by introducing a maleimide group or an amino group into a polymer having a fluorine-containing alicyclic structure.

Examples of the polymer having a fluorinated alicyclic structure include those obtained by polymerizing a monomer having a fluorinated cyclic structure and fluorinated monomers having at least two polymerizable double bonds. The polymer having a ring structure in the main chain obtained by the cyclopolymerization is exemplified in a wide range including known or well known polymers.

Polymers having a ring structure in the main chain obtained by cyclopolymerization of a fluorine-containing monomer having at least two polymerizable double bonds are disclosed in JP-A-63-238111 and 63-63. No. 238115, for example.
That is, it can be obtained by homopolymerization of a monomer such as perfluoro (allyl vinyl ether) or perfluoro (butenyl vinyl ether), or by copolymerization with a radical polymerizable monomer such as tetrafluoroethylene.

A polymer having a ring structure in its main chain, which is obtained by polymerizing a monomer having a fluorine-containing ring structure, is known from Japanese Patent Publication No. 63-18964. That is,
Obtained by homopolymerizing a monomer having a fluorinated ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole) or by copolymerizing with a radical polymerizable monomer such as tetrafluoroethylene. .

Further, perfluoro (2,2-dimethyl-
1,3-dioxole) and other fluorine-containing cyclic structure-containing monomers, and perfluoro (allyl vinyl ether) and perfluoro (butenyl vinyl ether) containing at least two polymerizable double bond-containing fluorine-containing monomers. It may be a polymer obtained by copolymerization.

The polymer having a fluorine-containing alicyclic structure is
A polymer having a ring structure in the main chain is preferable, but the number of repeating units having a ring structure is 20 with respect to the total number of repeating units.
% Or more is preferable in terms of transparency, mechanical properties and the like. More preferably, it is 40% or more.

Usually, a polymer having a fluorinated alicyclic structure has a carboxylic acid group derived from an initiator, a chain transfer agent or the like at its terminal. By modifying this carboxylic acid group into a maleimide group and an amino group, the polymer of the present invention can be obtained more. Further, in order to increase the introduction amount of these reactive groups to enhance the effect of the present invention, a small amount of CF _{2
= CFO (CF 2) 3 COOCH} 3, CF 2 = CFOC
F ₂ CF (CF ₃ ) O (CF ₂ ) ₃ COOCH ₃ , CF
_{2 = CFO (CF 2) 3} CN, CF 2 = CFO (CF
₂ ) ₃ CH ₂ NH ₂ etc. may be copolymerized.

As the maleimide group-containing fluoropolymer and amino group-containing fluoropolymer, perfluoro (2
-Butyltetrahydrofuran) having an intrinsic viscosity [η] measured at 30 ° C of 0.05 to 0.5 dl / g, particularly preferably 0.1 to 0.3 dl / g is preferably used.
If [η] is small, the proportion of the cross-linked structure is large, and the original physical properties of the polymer are impaired. In addition, if [η] is large, the effect of crosslinking is difficult to be exhibited. Further, in the reaction for modifying a carboxylic acid group described below into a maleimide group and an amino group, since the intrinsic viscosity hardly changes, a polymer having the above [η] as a polymer having a fluorine-containing alicyclic structure as a raw material By using, a maleimide group-containing fluoropolymer having the desired [η] and an amino group-containing fluoropolymer can be obtained.

A chain transfer agent is preferably used as a method for adjusting [η] of the polymer having a fluorine-containing alicyclic structure. The chain transfer agent is not particularly limited, and is well known,
Known ones can be used.

In the present invention, the maleimide group can be introduced by first introducing an amino group and then reacting with maleic anhydride. As a reaction condition, a known method can be used, but a method of mixing both the amino group-containing fluoropolymer and the maleic anhydride in a solvent is preferable. Furthermore, the reaction can be promoted by adding an acid catalyst such as p-toluenesulfonic acid, benzenesulfonic acid or glacial acetic acid. The reaction temperature is preferably room temperature to 150 ° C.

The method for introducing the amino group is not particularly limited and a known method can be used. However, if the modifying group is extremely long, it is not preferable in view of solubility. For example,
A method of converting to an amino group by reacting with a diamine utilizing a carboxylic acid group present in the fluoropolymer, or after reacting ammonia with the carboxylic acid group to form an amide, diborane-tetrahydrofuran, AlCl _3-
A method of converting to an amine using a reducing agent such as NaBH ₄ is also effective. Further, the above reaction may be carried out after esterifying the carboxylic acid group. A method of copolymerizing the above-mentioned amino group-containing monomer is also possible.

The maleimide group-containing fluoropolymer of the present invention causes a cross-linking reaction by itself. However, when it is used in combination with an amino group-containing fluoropolymer, a cross-linked product can be easily obtained under relatively mild conditions. It is possible. Further, the composition containing these two polymers can be crosslinked by heating at 150 to 300 ° C.

The maleimide group-containing fluorine-containing polymer and the amino group-containing fluorine-containing polymer are soluble in a specific fluorine-based solvent and can be mixed at any ratio, but from the viewpoint of physical properties of the polymer after heat crosslinking. The content of the maleimide group-containing fluoropolymer is 20 to 100% by weight, preferably 30 to 70% by weight, based on the total amount of both polymers. If the content of maleimide groups is small, the crosslinking reaction will not be sufficient.

The crosslinked product based on the crosslinkable fluorine-containing polymer composition of the present invention has a low dielectric constant of 2.0 to 2.5 and a water absorption of 0.1% or less, so that an insulating interlayer film in a semiconductor device, Used as a protective film. Further, the crosslinkable fluorine-containing polymer as it is or in combination with a reinforcing material such as glass cloth forms a low dielectric constant, heat resistant laminated material or prepreg.

Since the maleimide group-containing fluoropolymer and the amino group-containing fluoropolymer contained in the crosslinkable fluoropolymer composition of the present invention are soluble in a specific fluorine-based solvent, cast molding from a solution. A film having an arbitrary thickness can be prepared by the above method. It is also possible to perform heat-crosslinking after preforming by press molding or the like.

[0022]

EXAMPLES Next, examples of the present invention will be described more specifically, but it goes without saying that the description does not limit the present invention.

Synthesis Example 1 (Synthesis of Polymer Having Fluorine-Containing Aliphatic Ring Structure) Perfluoro (butenyl vinyl ether) 35 g, trichlorotrifluoroethane 5 g, ion-exchanged water 150
g, methanol 9 g, and diisopropyl peroxydicarbonate 90 mg as a polymerization initiator in an internal volume of 20
It was placed in a 0 ml pressure-resistant glass autoclave. After purging the system with nitrogen three times, suspension polymerization was carried out at 40 ° C. for 22 hours. As a result, 28 g of a polymer was obtained. The glass transition point of this polymer was 108 ° C., and it was a tough and transparent glassy polymer at room temperature. Thermogravimetric analyzer (TG
The thermal decomposition starting temperature according to A) was 360 ° C. When this polymer was dissolved in perfluorobenzene and ¹⁹ F-NMR was measured, it was confirmed to be a polymer having a fluorinated alicyclic structure. Further, when the IR spectrum of this polymer was measured, COOH absorption was observed at 1780 cm ^-1 . [Η] of this polymer is 0.24 dl
/ G.

Example 1 (Synthesis of Fluorine-Containing Polymer Containing Amino Group) --COOH present in the polymer of Synthesis Example 1 was converted to --COOC.
Replaced with H ₃ . 10 g of this polymer was added to perfluoro (2
-Butyltetrahydrofuran) was added to a solution of 90 g of ethylenediamine in 50 g of ethyl acetate. The system was replaced with nitrogen and the temperature was changed to 5 at room temperature.
Stir for hours.

The IR spectrum of the obtained polymer was measured. As a result, --COOC existing in the original fluoropolymer was found.
There is no absorption at 1800 cm ^-1 by H ₃ , and instead of this, around 1730 cm ^{-1 of} -CONH- and -CH ₂ NH.
₂ was observed to be absorbed at 1540 cm ⁻¹ , and it was confirmed that the polymer was an amino group-containing fluoropolymer.

Example 2 (Synthesis of Maleimide Group-Containing Fluorine-Containing Polymer) 10 amino-group-containing fluorine-containing polymer synthesized in Example 1 was used.
Perfluoro (2-butyltetrahydrofuran) containing g
To 100 g of the solution, 0.05 g of maleic anhydride was added as N, N-
A solution of 50 g of dimethylacetamide was added.
After purging the system with nitrogen, the mixture was stirred at 50 ° C. for 10 hours. When the IR spectrum of the obtained polymer was measured, absorption based on a maleimide group was observed at 1640 and 1710 cm ^-1 , and it was confirmed that the polymer was a maleimide group-containing fluoropolymer.

Example 3 1 part by weight of each of the amino group-containing fluoropolymer and the maleimide group-containing fluoropolymer synthesized in Examples 1 and 2 was dissolved in 40 parts by weight of perfluorotributylamine and crosslinked. It was a fluorinated polymer solution. This solution was cast on a polytetrafluoroethylene (PTFE) plate. A film having a thickness of 50 μm was prepared by heating at 50 ° C. for 5 hours and at 100 ° C. for 3 hours. This film could again be dissolved in perfluorotributylamine. Next, this film was placed in nitrogen at 200 ° C. for 2 hours.
Heat treated for hours. When this film was dissolved in perfluorotributylamine, this time it was not dissolved at all, confirming that a crosslinking reaction had occurred. In addition, this film showed no visible foaming.
The thermal decomposition starting temperature by TGA was 385 ° C.

This crosslinked film is approximately 3 mm wide and 3 c long.
The film was cut into a size of m and the elongation of the film was measured under various temperature conditions while applying a tensile load of 4.6 kg / cm ² . It was found that the heat distortion temperature was rising. In addition, the crosslinked film of 60 kHz
The relative permittivity at 1 MHz is 2.2, and the volume resistance is 10 ¹⁷ Ω ・
It was more than cm.

Comparative Example 1 1 part by weight of the polymer of Synthesis Example 1 was dissolved in 20 parts by weight of perfluorotributylamine and cast on a PTFE plate. 5
A film was prepared by heating at 0 ° C. for 5 hours and at 100 ° C. for 3 hours. In addition, this film was exposed to nitrogen at 200 ° C. for 2 hours.
Heat treated for hours. The results of measuring the thermal deformation behavior of this film by the same method as in Example 3 are shown in Table 1.

[0030]

[Table 1]

Synthesis Example 2 Perfluoro (butenyl vinyl ether) 8 g, perfluoro (2,2-dimethyl-1,3-dioxole) 2
g, 40 g of trichlorotrifluoroethane, and 0.1 g of diisopropyl peroxydicarbonate as a polymerization initiator were placed in a pressure-resistant glass ampoule having an internal volume of 50 ml. After freezing and degassing the system three times, in a water bath at 40 ° C for 20
I shook the time. As a result, 6.7 g of a polymer was obtained. The glass transition point of this polymer is 157 ° C., and [η] is 0.1.
It was 30 dl / g. 1930 cm of IR spectrum
The content of the unit based on perfluoro (2,2-dimethyl-1,3-dioxole) was determined from the absorbance of ^-1 absorption, and it was 12%.

Example 4 Using the polymer of Synthesis Example 2, an amino group-containing fluoropolymer and a maleimide group-containing fluoropolymer were synthesized in the same manner as in Examples 1 and 2, and 1 part by weight of each was used. It was dissolved in 40 parts by weight of fluorotributylamine to obtain a crosslinkable fluoropolymer solution. This solution was cast on a PTFE plate and heated at 50 ° C. for 5 hours and 100 ° C. for 3 hours to prepare a film. In addition, this film is placed in nitrogen for 20
A heat treatment was performed at 0 ° C. for 2 hours to prepare a crosslinked film. The results of measuring the thermal deformation behavior of this crosslinked film by the same method as in Example 3 are shown in Table 2.

Comparative Example 2 1 part by weight of the polymer of Synthesis Example 2 was dissolved in 20 parts by weight of perfluorotributylamine and cast on a PTFE plate. 5
A film was prepared by heating at 0 ° C. for 5 hours and at 100 ° C. for 3 hours. In addition, this film was exposed to nitrogen at 200 ° C. for 2 hours.
Heat treated for hours. The results of measuring the thermal deformation behavior of this film by the same method as in Example 3 are shown in Table 2.

[0034]

[Table 2]

Synthesis Example 3 22 g of perfluoro (2,2-dimethyl-1,3-dioxole), 16 g of tetrafluoroethylene, CF ₂ =
2 g of CFO (CF ₂ ) ₃ COOCH ₃ , 10 g of trichlorotrifluoroethane, 120 g of ion-exchanged water, and 90 mg of diisopropyl peroxydicarbonate as a polymerization initiator were placed in a pressure-resistant glass ampoule having an internal volume of 200 ml. After freezing and degassing the system 3 times, 40 in a water bath
Shake at 20 ° C. for 20 hours. As a result, 27 g of a polymer was obtained. The glass transition point of this polymer was 140 ° C.

Example 5 Using the polymer of Synthesis Example 3, an amino group-containing fluoropolymer and a maleimide group-containing fluoropolymer were synthesized in the same manner as in Examples 1 and 2, and 1 part by weight of each was used. It was dissolved in 40 parts by weight of fluorotributylamine to obtain a crosslinkable fluoropolymer solution. This solution was cast on a PTFE plate and heated at 50 ° C. for 5 hours and 100 ° C. for 3 hours to prepare a film. In addition, this film is placed in nitrogen for 20
A heat treatment was performed at 0 ° C. for 2 hours to prepare a crosslinked film. The results of measuring the thermal deformation behavior of this crosslinked film in the same manner as in Example 3 are shown in Table 3.

Comparative Example 3 1 part by weight of the polymer of Synthesis Example 3 was dissolved in 20 parts by weight of perfluorotributylamine and cast on a PTFE plate. 5
A film was prepared by heating at 0 ° C. for 5 hours and at 100 ° C. for 3 hours. In addition, this film was exposed to nitrogen at 200 ° C. for 2 hours.
Heat treated for hours. The results of measuring the thermal deformation behavior of this film by the same method as in Example 1 are shown in Table 3.

[0038]

[Table 3]

Example 6 After treating a silicon wafer with a silane coupling agent, the solution of the crosslinkable fluoropolymer used in Example 3 was spin-coated, the solvent was removed by drying at 150 ° C., and further 20
By heat treatment at 0 ° C., a film having a thickness of 7 μm was obtained. A copper thin film was formed on this film by a sputtering method. This copper thin film was etched to form a pattern of 10 μL / S. The polymer solution was again spin-coated on this to prepare a polymer / copper / polymer laminate. This laminated plate is placed in an atmosphere of 125 ° C. and 100% relative humidity for 30 minutes.
After leaving for 0 hours, no abnormalities such as peeling were observed.

Example 7 After treating a silicon wafer with a silane coupling agent, the solution of the crosslinkable fluorine-containing polymer used in Example 4 was spin-coated, the solvent was removed by drying at 150 ° C., and further 20
A film having a thickness of 2 μm was obtained by heat treatment at 0 ° C.
A test pattern was formed on this film by a lithography method and dry etching. After heating this at 300 ° C. for 10 minutes, the pattern was observed with a microscope, and there was no deformation. Further, since no generation of decomposed gas was observed, it was found that it has good characteristics as a passivation film for ICs or multichip modules.

Example 8 A glass plate was dip-coated with the crosslinkable fluorine-containing polymer solution used in Example 3, the solvent was dried and removed at 150 ° C., and heat treatment was further performed at 200 ° C. to form an antireflection film on the glass. Created on the surface. When the reflectance of light at 550 nm was measured, the uncoated one was 8.6%, while the antireflection coated one was 0.3%.

Example 9 After treating a glass plate with a silane coupling agent, the crosslinkable fluoropolymer solution used in Example 3 was dip-coated, the solvent was removed by drying at 150 ° C., and the solution was heated at 200 ° C. An antireflection film was formed on the glass surface by the treatment. When the reflectance of light at 550 nm was measured, the uncoated one was 8.6%, while the antireflection coated one was 0.3%.

Example 10 The scratch resistance was evaluated by the method shown in Table 4 using the samples prepared in Examples 8 and 9. As Comparative Example 4, the glass coated with the polymer of Synthesis Example 1 was also evaluated. The results are shown in Table 5.

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

EFFECTS OF THE INVENTION The crosslinked product of the polymer composition having a crosslinkable fluorine-containing alicyclic structure of the present invention has a low dielectric constant, low water absorption, low surface energy, water repellency, or low refractive index as a fluororesin. It also has the properties that the heat distortion temperature and the thermal decomposition temperature are high while the excellent properties are maintained, and the abrasion resistance is also excellent. Since it is soluble in a solvent, a coating molding method such as dip coating or spin coating can be used. Utilizing these various excellent properties, it is useful as a laminated material such as a semiconductor protective film / insulating material or a circuit board. Further, it is also used as various antireflection coatings or protective coating materials.

Claims (4)

[Claims] 1. A polymer having a fluorinated alicyclic structure and having a maleimide group represented by the general formula (1) in its molecule. [Chemical 1] _2. A polymer having a fluorinated alicyclic structure and having an --NH ₂ group in its molecule. 3. A polymer having a fluorinated alicyclic structure and having a maleimide group represented by the general formula (1) in its molecule, and -NH ₂ having a fluorinated alicyclic structure in its molecule.
A crosslinkable fluoropolymer composition comprising a polymer having a group. [Chemical 2] 4. A cross-linking method, wherein the cross-linkable fluoropolymer composition having a fluorinated alicyclic structure according to claim 3 is cross-linked by heating at a temperature range of 100 to 300 ° C.