JPH0745535B2 - Methanol-insoluble thin film composed of fluorine-containing polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a Langmuir-Bloe polymer compound, which was previously applied (Japanese Patent Application No. 1350 in 1987), in which a part of the amino group in polyallylamine was modified with a perfluoroalkyl group. The present invention relates to a methanol-insoluble thin film obtained by heat-treating a jet film.

A polymer compound modified with a long-chain perfluoroalkyl group exhibits excellent properties such as water repellency, oil repellency, antiseptic property, heat resistance and solvent resistance, and is used as a surface modifier and a substrate protector. ing. However, a soluble fluorine-containing polymer compound must be used for applying a fluorine-containing polymer compound on a substrate or for producing an ultrathin film by the Langmuir-Blodgett method. This has the drawback that even if the produced thin film shows solvent resistance due to a perfluoroalkyl group, the polymer film dissolves in a soluble solvent and cannot be used as a surface modifier. On the other hand, it is known that polyallylamine is crosslinked by heat treatment to increase the molecular weight of the polymer and insolubilize it in a solvent [functional material, 5 (12), 29 (1985)].

[0003]

However, the polyallylamine modified with a long-chain perfluoroalkyl group has a molecular weight increase due to the perfluoroalkyl group, and further, the amino group density is low, so that it can be said that the crosslinking proceeds by heat treatment. Absent. In addition, the cross-linking of molecularly aligned polymers produced by the Langmuir-Blodgett method in ultrathin films is not known.

[0004]

Means for Solving the Problems As a result of intensive studies on heat treatment of fluorine-containing polyallylamine, the present inventor has found that when the ratio of introduction of perfluoroalkyl groups to amine groups in polyallylamine is low, Langmuir The inventors have found that crosslinking occurs in a thin film produced by the blow jet method by heat treatment, and completed the present invention.
The present invention has the general formula (I)

[Chemical 1] A fluorine-containing polymer compound represented by the formula (wherein Rf has 6 carbon atoms)
~ 15 perfluoroalkyl group, m is 10 to 1
The number of 500 is shown, and n is a number satisfying 0 <n ≦ 0.4 m), which is 430 by thermogravimetric analysis obtained by heat-treating a monomolecular film produced by the Langmuir-Blodgett method or a cumulative film. The present invention provides a methanol-insoluble polymer ultra-thin film showing a thermal decomposition peak in the range of ˜460 ° C.

The heat treatment in the present invention is carried out in air, an inert gas, or under reduced pressure or under pressure at 40 ° C. to 200 ° C.
C., preferably in the range of 60.degree. C. to 120.degree. As the inert gas, nitrogen, argon, helium or the like is used. Crosslinking by heat treatment begins shortly after heating. Usually, heating for 1 to 24 hours is sufficient, but the fluorine-containing polymer compound obtained in the treatment time of the heat treatment has a different degree of cross-linking, so that it can be treated for a longer time if desired.

The Langmuir-Brosette film (hereinafter also referred to as an LB film) of the fluorine-containing polymer compound represented by the general formula (I) obtained in the present invention, when heat-treated, shows properties different from those of the non-heat-treated product. I found out that it is shown below. [Solvent resistance] The LB film of the unheated compound is soluble in methanol, whereas the heat-treated LB film is insoluble in methanol. In the fluorine-containing polymer compound represented by the general formula (I), when n = 0.05 m is PAAF5 and n = 0.2 m is PAAF20, the monomolecular film and cumulative film of PAAF5 are soluble in methanol and When soaked in the film, the thin film peels off from the substrate and dissolves in methanol, resulting in low solvent resistance. However, the heat-treated PAAF5 film remains on the substrate even after being immersed in methanol for 1 day. In the case of PAAF20, both the heat-treated and non-heat-treated films remain on the substrate even when immersed in methanol, but the heat-treated film improves the surface condition.

[Measurement of Contact Angle] The critical surface tension (γc dyn / cm) determined from the Zisman plot by measuring the contact angle of the surface of the polymer film with respect to the n-alkane was measured. Regarding the thin films produced by the Langmuir-Blodgett method, the untreated films were both 18.5 for PAAF5 and 16. for PAAF20.
While showing a γc value of 2-16.5, in air, 90 ° C
The thin film that was heat-treated at 20.3 was a PAAF5 monolayer.
(24-hour treatment), 18.5 with PAAF20 monolayer
(2 hours processing), 18.6 (24 hours processing), PAAF
The 7-layer cumulative film of 20 shows a value of 18.0 (24-hour treatment), and it can be seen that the γc value increases by about 2 by heat treatment. However, it can be seen that even when the heat treatment is performed, excellent surface properties are exhibited, which is almost the same as the γc value of polytetrafluoroethylene of 18.5. Although PAAF5 and PAAF20 do not dissolve in hexane or water and show solvent resistance, they dissolve well in methanol. Therefore, the thin film prepared by the Langmuir-Blodgett method was immersed in methanol for 24 hours to measure the γc value. The untreated PAAF5 was neither on the substrate nor on the substrate, and the γc value could not be measured because it was dissolved in methanol, but the monolayer heat-treated at 90 ° C. in air was 22.7 (24). Γc value of (time heating) was shown. P
In AAF20, for example, in the case of a heat-untreated seven-layer cumulative film, when immersed in methanol, the film is on the substrate, but the γc value increases to 19.6. 1 for a film that was heat treated in air at 90 ° C
It was as small as 7.9 (heating for 24 hours), and it can be seen that the solvent resistance to methanol was improved by the heat treatment.

[Thermogravimetric Measurement] The weight change of the fluorine-containing polymer compound represented by the general formula (I) upon heating was measured by thermogravimetric measurement (TG). 5 (PAAF5), 20 (PAAF20), 40, to the amino group in polyallylamine
Samples containing 60, 80, and 100% perfluoroalkyl groups were dried under reduced pressure at 80 ° C., and thermogravimetric measurements were carried out under nitrogen. As a result, 200 to 230 ° C. (decomposition 1), 2
Four thermal decompositions having a decomposition peak at 90 to 310 ° C (decomposition 2), 360 to 390 ° C (decomposition 3), and 430 to 460 ° C (decomposition 4) were observed. Decomposition 3 and decomposition 4 were the main decompositions. In a sample having a perfluoroalkyl group content of more than 40%, only internal decomposition 3 occurs, and in a sample of 40% or less, decomposition 2, decomposition 3 and decomposition 4 coexist, and the decomposition rate is the sum of decomposition 2 and decomposition 3. The ratio of the decomposition 4 to that of the decomposition 4 is correlated with the introduction percentage of the perfluoroalkyl group, and the decomposition 3 increases as the ratio of the introduced perfluoroalkyl group increases. From this, it can be said that the decomposition at high temperature, that is, decomposition 4, was caused by the increase in the molecular weight of the polymer due to the crosslinking reaction and the decomposition temperature became higher, and the decomposition at low temperature, that is, decomposition 2 + 3 was It can be said to be disassembly. When the introduction percentage of the perfluoroalkyl group becomes large, the intersection of the polyallylamines is hindered, and further the crosslinking of the amino group becomes an amide bond, which makes it difficult for the crosslinking to proceed. However, in a sample of 40% or less, decomposition 4 is observed and it is clear that crosslinking proceeds. Thermogravimetric measurement in nitrogen is performed for samples that have not been heat-treated in nitrogen (partly heat-treated during temperature increase) and for samples that have been heat-treated in air at 90 ° C. with an introduction percentage of 40% or less. And the same decomposition 2, decomposition 3, and decomposition 4 as the sample dried under reduced pressure at 80 ° C. described above, and the proportions thereof also draw almost the same decomposition curve, heat treatment in air, nitrogen, and reduced pressure. Can be said to obtain almost the same crosslinked polymer compound. In addition, it can be said that the heat treatment temperature is appropriate up to around 200 ° C. where decomposition 1 occurs, because the weight of the polymer hardly changes.

The above-mentioned fluorine-containing polymer compound of the general formula (I) is obtained by reacting a polyallylamine represented by the following general formula (II) with an alkyl perfluorocarboxylate represented by the general formula (III) according to the following formula. Manufactured by

[Chemical 2] However, in the above formula, Rf, m, and n have the same meanings as described above, and R is an alkyl group having 1 to 5 carbon atoms.

In the above reaction, alcohol is used as a reaction solvent, and the reaction temperature is -10 ° C to 50 ° C, preferably 1
It can be carried out using 5 ° C to 30 ° C. Polyallylamine is obtained by neutralizing polyallylamine hydrochloride with a base. In order to carry out the above reaction preferably, alkyl perfluoroalkylcarboxylate is added to a solution part obtained by neutralizing polyallylamine hydrochloride in alcohol or to an alcohol solution of polyallylamine obtained by dissolving polyallylamine in alcohol. The perfluoroalkyl group can be introduced into the polyallylamine at an arbitrary ratio by changing the amount of the perfluoroalkylcarboxylic acid added. In this case, as the reaction progresses, fluorine-containing polyallylamine is precipitated in the case of high fluoride, but reacts in a homogeneous system in the case of low fluoride. A few minutes (low fluoride) to 1
After stirring for a day (high fluoride), the reaction solution is concentrated and washed with water, and the obtained polymer substance is dried. This product was identified as a fluorine-containing polyallylamine represented by the above general formula (I) by the fluorine analysis value and IR spectrum.
The low fluoride in the fluorine-containing polymer substance dissolves in a solvent and easily forms a monomolecular film on the water surface, and a Langmuir-Blodgett accumulated film (Y film) can be prepared.

[0011]

The low fluorine compound of the general formula (I) (40%
The following) is a soluble polymer compound, but becomes an insoluble cross-linked polymer compound by heat treatment after film formation and molding. This is particularly important as a material, solvent resistance and durability are obtained, and it becomes a practical material. That is, when forming an ultrathin film by a cast film or Langmuir-Blodgett method, it is necessary to use a soluble polymer, which has the drawback of lacking solvent resistance after film formation.
An excellent film having solvent resistance could be produced by heat treatment after film formation. In particular, the film produced by the Langmuir-Blodgett method has a small film thickness and thus has low strength, and reinforcement of such a film is important. Further, the crosslinking reaction on the polymer film produced by the Langmuir-Blodgett method has not been conventionally performed, and the present invention is the first.

[0012]

EXAMPLES The present invention will now be described in more detail with reference to Examples.

Example 1 In the fluorine-containing polymer compound represented by the general formula (I), 5% (PAAF5) and 20% (PAAF20) of the amino groups in polyallylamine were selected from perfluoroalkyl groups (n-).
C ₇ F ₁₅ -) were introduced compound in vacuo (0.1MmH
g), heated at 80 ° C. for 8 hours. The heat-untreated fluoropolymer is obtained as a methanol solvent during synthesis and is soluble. 1 mg of the isolated PAAF5 is soluble in 2 ml of methanol. However, the heat-treated sample is PAAF5, PA
Both AF20 were insoluble in methanol. Untreated P
From AAF5 and PAAF20, a monolayer film and a cumulative film were formed on a glass substrate by a cast film and a Langmuir-Brommet method, and then in air, nitrogen, and reduced pressure (0.1 mmHg) at 90 ° C. for 2 hours. And 24
Heated for hours. The heat-treated PAAF5 film remained on the substrate even after being treated with methanol for 24 hours at room temperature. However, the heat-treated or PAAF5 film was not present on the substrate due to the dissolution of methanol. In the case of the PAAF20 film, when the same treatment was performed, both the heat-untreated and the heat-treated were on the substrate.

Example 2 About the film obtained in Example 1, n-alkane (carbon number: 8 to 8
The contact angle with 16) was measured at 20 ° C., and the critical surface tension γc dyn / cm 2 determined from the Zisman plot was measured. As a result, the monomolecular film produced by the Langmuir-Blodgett method of PAAF5 was 18.5 (room temperature drying), 20.5 (heating in air for 2 hours), 20.3 (heating in air for 24 hours), and 22. 8 (heated in air for 2 hours and treated with methanol for 24 hours) and 22.7 (heated in air for 24 hours and treated with methanol for 24 hours) were shown.
In addition, for the monolayer of PAAF20, 16.4 (room temperature drying), 18.5 (heating in air for 2 hours), 18.6 (heating in air for 24 hours), 18.8 (room temperature drying, treatment with methanol for 24 hours). ), 18.1 (heating in air for 2 hours and then treating with methanol for 24 hours), 18.7 (heating in air for 24 hours and then treating with methanol for 24 hours). Further, in the 7-layer cumulative film of PAAF20, 16.2 (room temperature drying), 17.0 (heating in air for 2 hours), 18.0 (heating in air for 24 hours), 19.6 (room temperature drying, methanol for 24 hours). (Treatment), 18.6 (heating in air for 2 hours, then treatment with methanol for 24 hours), 17.9 (heating in air for 24 hours, treatment with methanol for 24 hours).

Example 3 About 5 mg of the sample shown in the table for thermogravimetric measurement was used, and the temperature rising rate was 10 ° C./min, under a nitrogen or air stream (200 ml / min.
The results measured by TG50 manufactured by METTLER CORPORATION are shown in the table.

[0016]

[Table 1]

Claims (1)

[Claims] 1. A compound represented by the general formula (I): (In the formula, Rf represents a perfluoroalkyl group having 6 to 15 carbon atoms, m represents a number of 10 to 1500, and n represents 0 <n ≦.
Which is a number satisfying 0.4 m), insoluble in methanol showing a thermal decomposition peak in the range of 430 to 460 ° C. by thermogravimetric analysis obtained by heat-treating a Langmuir-Blodgett film of a fluorine-containing polymer represented by Thin film.