JP4899329B2 - Oil-repellent composition and article having oil-repellent film - Google Patents

Description

  The present invention relates to an oil-repellent composition and an article having an oil-repellent film made of the oil-repellent composition.

An oil repellent containing a fluorine-containing polymer is used as an oil sealant for preventing oil from seeping out from a fluid bearing portion of a motor in an electronic device or the like. For example, in a fluid bearing portion in a cooling fan motor for a microprocessor, an optical disk rotating device, a computer hard disk, etc., a fluorine-containing end face of the bearing or sleeve is used to prevent the oil filled as a lubricant from oozing out. An oil repellent film made of an oil repellent containing a copolymer is provided (for example, see Patent Document 1). Further, as a fluorine-containing copolymer having oil repellency, a polymer having a fluorine-containing aliphatic ring structure in the main chain is also known (for example, see Patent Document 2).
However, since the temperature of the oil in the fluid bearing portion rises due to heat generation from the motor portion, the oil repellent film is exposed to high temperature oil, and the oil may penetrate into the oil repellent film. Therefore, the oil repellent film swells, the adhesion between the oil repellent film and the bearing or the sleeve decreases, and the oil repellent property of the oil repellent film decreases, and the function of preventing oil bleeding is impaired.

The fluorine-containing resin composition having excellent adhesion to the substrate includes a fluorine-containing resin having a fluorine-containing ring structure and a fluorine-containing compound having a polar functional group and soluble in a fluorine-based solvent. A composition has been proposed (see Patent Document 3). However, although the oil-repellent film of the composition is excellent in initial oil repellency, the oil repellency is lowered depending on use conditions, and the oil may not be completely repelled.
JP 2000-297818 A JP-A-63-238111 JP 2004-115622 A

  The object of the present invention is to provide an oil-repellent film that is excellent in oil repellency, does not deteriorate in adhesion to a substrate even when exposed to high-temperature oil for a long time, and has excellent oil repellency. Another object of the present invention is to provide an oil-repellent composition having excellent film formability and an article having excellent oil repellency and durability.

（式（８）〜（１０）中、Ｙ^１〜Ｙ^１０、Ｚ^１〜Ｚ^８、およびＷ^１〜Ｗ^８は、それぞれ独立にＦまたはＣＦ_３である。） The oil-repellent composition of the present invention is a polymer having a fluorine-containing aliphatic ring structure in the main chain and having a carboxyl group , the polymer (a) having a number average molecular weight of 10,000 to 5,000,000 , a fluorine-containing polymer is a perfluoropolyether which the main chain does not have a fluorinated aliphatic ring structure, a number average molecular weight of 6 000 to 15 000 polymer and (b), by containing the solvent Wherein the polymer (a) has 1 to 10 carboxyl groups per 10,000 to 5,000,000 in the number average molecular weight of the polymer (a), and all the structural units of the polymer (a) A polymer having 20 mol% or more of a structural unit having a fluorinated aliphatic ring structure in 100 mol%, wherein the content of the polymer (b) is from 1 to 50 masses per 100 mass parts of the polymer (a). It is a part.
The polymer (a) is a polymer obtained by polymerizing a monomer having a fluorine-containing aliphatic ring structure in the presence of an initiator, and a fluorine-containing monomer having two or more polymerizable double bonds is used as an initiator. Copolymerization of a polymer obtained by cyclopolymerization in the presence of a monomer, or a monomer having a fluorine-containing aliphatic ring structure and a fluorine-containing monomer having two or more polymerizable double bonds in the presence of an initiator It is preferable that the initiator is an initiator having a carboxyl group or its precursor group in the molecule.
The fluorine-containing monomer having two or more polymerizable double bonds is preferably a compound represented by the following formulas (8) to (10).

(In Formulas (8) to (10), Y ^{1 to} Y ¹⁰ , Z ^{1 to} Z ⁸ , and W ^{1 to} W ⁸ are each independently F or CF _3. )

The polymer (b) is such that the contact angle of n-hexadecane with respect to the coating film made of the polymer (b) is larger than the contact angle of n-hexadecane with respect to the coating film made of the polymer (a). Is preferred .
The oil-repellent composition of the present invention can be used for an application as an oil sealant.
The article of the present invention is characterized by having an oil repellent film comprising the oil repellent composition of the present invention.

The oil-repellent composition of the present invention is excellent in oil repellency, can be obtained an oil-repellent film excellent in oil repellency, without lowering the adhesion to the substrate even when exposed to high-temperature oil for a long time, and Excellent solution stability and film formability.
The article of the present invention is excellent in oil repellency and durability.

Oil repellency composition of the present invention have a fluorinated aliphatic ring structure in its main chain, perfluoropolyether having no polymer to have a carboxyl group and (a), a fluorinated aliphatic ring structure in its main chain It is a fluorine-containing polymer which is an ether, and is a composition containing a polymer (b) having a number average molecular weight of 3000 to 20000 and a solvent.

(Polymer (a))
The polymer (a) has a fluorine-containing aliphatic ring structure in the main chain. “Having a fluorinated aliphatic ring structure in the main chain” means that one or more of the carbon atoms constituting the aliphatic ring is a carbon atom in the carbon chain constituting the main chain, and the carbon constituting the aliphatic ring It means having a structure in which a fluorine atom or a fluorine-containing group is bonded to at least a part of the atoms. In addition, the aliphatic ring may have an ether bond.

  As the polymer (a), a polymer (a-1) obtained by polymerizing a monomer having a fluorinated aliphatic ring structure, and a fluorinated monomer having two or more polymerizable double bonds are cyclopolymerized. A polymer (a-2) obtained by copolymerization of a monomer having a fluorine-containing aliphatic ring structure and a fluorine-containing monomer having two or more polymerizable double bonds (a-3) ) And the like.

  As the polymer (a-1), those described in Japanese Patent Publication No. 63-18964 are known. The polymer (a-1) is obtained by homopolymerizing, for example, a monomer having a fluorine-containing aliphatic ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole), or the monomer and another radical. It is obtained by copolymerizing a polymerizable monomer.

  As the polymer (a-2), those described in JP-A-63-238111 are known. The polymer (a-2) is, for example, cyclopolymerization of a fluorine-containing monomer having two or more polymerizable double bonds such as perfluoro (allyl vinyl ether), perfluoro (butenyl vinyl ether), or the like. It is obtained by copolymerizing a monomer and another radical polymerizable monomer.

  Specific examples of the polymers (a-1) to (a-3) include those having structural units selected from the following formulas (1) to (4).

In formulas (1) to (4), h is an integer of 0 to 5, i is an integer of 0 to 4, j is 0 or 1, h + i + j is 1 to 6, s is an integer of 0 to 5, and t is 0 to 0. An integer of 4, u is 0 or 1, s + t + u is 1-6, p, q, r are each independently an integer of 0-5, p + q + r is 1-6, R, R ¹ , R ² , X ¹ , X ² Are each independently F or CF ₃ .

  As the monomer having a fluorine-containing aliphatic ring structure, compounds represented by the following formulas (5) to (7) are preferable.

In the formulas (5) to (7), X ^{3 to} X ⁸ and R ^{3 to} R ⁸ are each independently F, Cl or CF ₃ , and R ³ and R ⁴ , R ⁵ and R ⁶ , and R ⁷ R ⁸ may be linked to form a ring.
Specific examples of the compounds represented by formulas (5) to (7) include the following formulas (5-1) to (5-3), (6-1) to (6-3), and (7-1). , (7-2) and the like.

  As the fluorine-containing monomer having two or more polymerizable double bonds, compounds represented by the following formulas (8) to (10) are preferable.

In formulas (8) to (10), Y ^{1 to} Y ¹⁰ , Z ^{1 to} Z ⁸ , and W ^{1 to} W ⁸ are each independently F or CF ₃ .
Specific examples of the compounds represented by the formulas (8) to (10) include the following compounds.

  Examples of other radical polymerizable monomers that can be copolymerized with a monomer having a fluorine-containing aliphatic ring structure or a fluorine-containing monomer having two or more polymerizable double bonds include tetrafluoroethylene, chlorotrifluoroethylene, and trifluoroethylene. , Vinylidene fluoride, hexafluoropropylene, (perfluorobutyl) ethylene, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether), methyl perfluoro (5-hex-6-heptenoate, ethylene, propylene, and the like.

  From the viewpoint of adhesion to the substrate, the polymer (a) is a carboxyl group, a sulfo group, a group having an ester bond, a hydrolyzable silyl group, a nitrile group, an isocyanate group, an epoxy group, an amino group, a vinyl group, It preferably has at least one functional group selected from the group consisting of an acryloyloxy group, a methacryloyloxy group, a mercapto group, and a diazo group. The number of functional groups in the polymer (a) is preferably 1 to 10, more preferably 1 to 5, more preferably 1 to 2 per number average molecular weight 10,000 to 5,000,000 of the polymer (a). preferable. As the polymer (a), a polymer (a) having a functional group and a polymer (a) having no functional group may be used in combination.

Examples of the method for introducing a functional group into the polymer (a) include the following methods.
(I) Polymerization in the presence of an initiator or a chain transfer agent having a functional group such as a carboxyl group or a sulfo group in the molecule, or a precursor group thereof (for example, an acyl group in the case of a carboxyl group). To introduce a carboxyl group, a sulfo group or the like into the terminal group of the polymer (a).
(Ii) The polymer (a) is treated at a high temperature in the presence of oxygen to oxidatively decompose the side chain or terminal of the polymer (a), and then treated with water or alcohol to produce a carboxyl group or ester. A method for introducing a group having a bond.

(iii) A method of introducing a functional group into the side chain of the polymer (a) by copolymerizing a monomer having a carboxylic acid derivative group, a sulfo group, or a sulfo group derivative group.
(Iv) A method of converting the functional group introduced by the methods (i) to (iii) into another functional group by a known method.

As the monomer having a carboxylic acid derivative group in the method (iii), methyl perfluoro (5-oxa-6-heptenoate) [CF ₂ = CFOCF ₂ CF ₂ CF ₂ CO ₂ CH ₃ ], CF ₂ = CFOCF ₂ CF _{(CF 3) O (CF 2} ) 3 CO 2 CH 3 and the like.
Examples of the monomer having a sulfo group derivative group include CF ₂ ═CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F, CF ₂ ═CFOCF ₂ CF ₂ SO ₂ F, and the like.

  As a method of (iv), for example, as described in Japanese Patent No. 3029323, a solution of a silane coupling agent is added to the solution of the polymer (a), and the carboxyl at the terminal of the polymer (a) is added. Examples thereof include a method in which a functional group (such as an amino group) of a silane coupling agent is reacted with a group to introduce a hydrolyzable silyl group.

The polymer (a) preferably has 20 mol% or more of a structural unit having a fluorinated aliphatic ring structure in 100 mol% of all the structural units of the polymer (a), and has viewpoints such as transparency and mechanical properties. To 40 mol% or more is particularly preferable.
In addition, the fluorine content of the polymer (a) is preferably 40 to 75% by mass in 100% by mass of the polymer (a) from the viewpoint of solvent solubility, coatability, processability, mechanical strength, and the like. 70% by mass is particularly preferred.
The number average molecular weight of the polymer (a) is preferably 10,000 to 5,000,000, more preferably 40,000 to 1,000,000.

(Polymer (b))
The polymer (b) is a fluorine-containing polymer having no fluorine-containing aliphatic ring structure in the main chain, and is a polymer having a number average molecular weight of 3000 to 20000.
As the polymer (b), those having good compatibility with the polymer (a) are preferable. The compatibility with the polymer (a) is improved by reducing the molecular weight of the polymer (b) or increasing the fluorine content of the polymer (b). Polymers such as the polymer (b) lose their crystallinity and have a low molecular weight, so that they are often in the form of grease or oil, and an oil repellent film excellent in film strength cannot be formed with the polymer (b) alone.

  The polymer (b) is such that the contact angle b of n-hexadecane with respect to the coating film made of the polymer (b) is larger than the contact angle a of n-hexadecane with respect to the coating film made of the polymer (a). Is preferred. The polymer (b) having a contact angle b larger than the contact angle a is selected and mixed with the polymer (a), thereby maintaining the film strength of the polymer (a) while maintaining the polymer (a). ) Oil repellency that cannot be achieved with only) is obtained.

  Examples of the polymer (b) include an oligomer (b-1) composed of a fluorine-containing monomer and perfluoropolyether (b-2). Of these, perfluoropolyether (b-2) is preferred because of excellent compatibility with the polymer (a), good adhesion to the substrate, and improved oil repellency.

  Examples of the fluorine-containing monomer constituting the oligomer (b-1) include tetrafluoroethylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), vinylidene fluoride, (perfluoroalkyl) ethylene, trifluoroethylene, hexafluoropropylene, and the like. Is mentioned.

  As the perfluoropolyether (b-2), those represented by the following formulas (11) to (13) are preferable.

In formula (11), X ¹¹ and X ¹³ are each independently CF ₃ , C ₂ F ₅ , C ₃ F ₇ , C ₄ F ₉ , C ₆ F ₁₃ , C ₈ F ₁₇ , C ₁₀ F ₂₁ , or C ₁₂ F ₂₅ , X ¹² is F or CF ₃ , n1, n2, and n3 are integers of 0 to 300, and 10 ≦ n1 + n2 + n3 ≦ 300.
In the formula (12), X ¹⁴ and X ¹⁵ are each independently CF ₃ , C ₂ F ₅ , C ₃ F ₇ , C ₄ F ₉ , C ₆ F ₁₃ , C ₈ F ₁₇ , C ₁₀ F ₂₁ , or C ₁₂ F ₂₅ and n4 is an integer of 10 to 120.
In formula (13), n5 is an integer of 18-120.

The number average molecular weight of the polymer (b) is 3000 to 20000, preferably 6000 to 15000. By setting the number average molecular weight of the polymer (b) to 3000 or more, the thermal stability becomes sufficient, it does not volatilize when the heat treatment is performed after film formation, and it dissolves in oil during oil immersion. There is nothing to do. By setting the number average molecular weight of the polymer (b) to 20000 or less, the solubility in the polymer (a) becomes high and phase separation hardly occurs, and the strength of the oil repellent film becomes sufficient.
It is preferable that there is no group which reacts with the functional group of a polymer (a) at the terminal of a polymer (b), or there are few such groups.

  The content of the polymer (b) with respect to 100 parts by mass of the polymer (a) is preferably 1 to 50 parts by mass and more preferably 1 to 40 parts by mass from the viewpoint of the balance between the oil repellency and mechanical strength of the oil repellent film. Preferably, 3 to 35 parts by mass are particularly preferable.

(solvent)
As the solvent, those capable of dissolving the polymer (a) and the polymer (b) at the same time are preferable.
Examples of the solvent include perfluoroalkanes such as perfluorooctane and perfluorohexane; perfluoroalkyl-substituted ethylenes such as CF ₃ (CF ₂ ) _n CH═CH ₂ (n is an integer of 5 to 11); Perfluoroalkyl-substituted ethanes such as CF ₃ (CF ₂ ) _n CH ₂ CH ₃ (n = integer of 5 to 11); perfluorobenzenes; perfluorotrialkylamines; perfluoro (alkylhydrofurans) Hydrofluoroethers represented by C _n F _{2n + 1} OC _m H _{2m + 1} (n = integer of 3-12, m = 1-3, n>m); C _n F _{2n + 1} And hydrofluorocarbon represented by H (n = integer of 4 to 12). These may be used alone or in a mixture of two or more.

  You may mix pigments, such as dye and a pigment, with the oil-repellent composition of this invention. When a pigment is mixed, it becomes easy to confirm the presence or absence of an oil repellent film, and the visibility is excellent. Moreover, in order to improve adhesiveness, you may add a silane coupling agent, a primer, etc. to such an extent that oil repellency and the storage stability of a solution are not impaired.

(Goods)
The article of the present invention has an oil repellent film made of an oil repellent composition on the surface of a substrate.
Examples of the substrate include resin, metal, fiber and the like. The substrate may be subjected to pretreatment such as corona treatment and UV ozone treatment, primer treatment, and the like. By this treatment, the adhesion between the oil repellent film and the substrate is improved. Examples of the primer include a coupling agent such as aminosilane and epoxysilane, and a primer mainly composed of amino group or epoxy group-containing silicone oligomer.

The oil repellent film is formed, for example, by applying the oil repellent composition of the present invention to a substrate and completely evaporating the solvent. Examples of the application method include spraying, dipping, brushing, potting, and spinning.
In order to improve the adhesion between the oil repellent film and the substrate, the oil repellent film may be heat-treated, and thermal energy such as far-infrared irradiation or electron beam may be applied to the oil repellent film. The heat treatment is preferably carried out for 30 minutes or more at a temperature not higher than the heat resistance temperature of the substrate and not lower than Tg of the mixture of the polymer (a) and the polymer (b).

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated, this invention is not limited to these.
The oil repellency was evaluated by the following method.
(Initial oil repellency)
About 1 μL of n-hexadecane was dropped on the test plate, and the contact angle was measured. The oil seal performance was evaluated by the contact angle of n-hexadecane. When the contact angle was 50 degrees or more, it was determined that there was oil sealability, and when it was less than 50 degrees, it was determined that there was no oil sealability.
(Oil repellency endurance)
The test plate was dipped in n-hexadecane at 120 ° C. for 40 hours, pulled up, dried using an air gun, and the contact angle of n-hexadecane was measured in the same manner as described above.

(Contact angle)
The contact angle was measured by the droplet method under the condition of 25 ° C. using Kyowa Interface Science CA-A.
(Number average molecular weight)
The number average molecular weight was measured using a gel permeation chromatograph (GPC) and dichloropentafluoropropane as a solvent.

[Example 1]
In an autoclave made of pressure-resistant glass, 100 g of CF ₂ = CFOCF ₂ CF ₂ CF = CF ₂ , 0.5 g of CH ₃ OH as a chain transfer agent and ((CH ₃ ) ₂ CHOC (O) O) ₂ as a polymerization initiator Of 0.7 g was sealed. The inside of the autoclave was kept at 40 ° C. for 22 hours to conduct a polymerization reaction to obtain a polymer. The obtained polymer had an intrinsic viscosity of 0.2 dl / g in perfluoro (2-butyltetrahydrofuran) at 30 ° C.
The obtained polymer was heat-treated in a hot air circulation oven at 300 ° C. for 1 hour in an air atmosphere, further immersed in ultrapure water at 110 ° C. for 1 week, and then vacuum dried at 100 ° C. for 24 hours. To obtain a polymer A.
As a result of analyzing polymer A by IR spectrum, a peak attributed to a carboxyl group was confirmed. In addition, the polymer A had a glass transition point of 108 ° C., was tough and transparent glass at 25 ° C., and had a light transmittance of 95% or more. Further, the 10% thermal decomposition temperature of the polymer A was 465 ° C. Moreover, the contact angle of n-hexadecane with respect to the coating film consisting of the polymer A was 52 degrees.

1.4 g of the polymer A and a perfluoropolyether [CF ₃ [(OCF ₂ CF ₂ ) _p- (OCF ₂ ) _q ] -OCF ₃ having a number average molecular weight of 13,000, p = 1 to 100, q = 1 to 140, n-hexadecane contact angle of 64 degrees. ] Was dissolved in 98 g of perfluorooctane to obtain an oil-repellent composition. The obtained oil-repellent composition is applied to a washed SUS plate using a spin coating method at 500 rpm for 20 seconds, and heat-treated at 120 ° C. for 60 minutes to obtain a test plate having an oil-repellent film. It was. The test plate was evaluated for initial oil repellency and oil repellency. The results are shown in Table 1.

[Example 2]
1.4 g of the polymer A and a perfluoropolyether [CF ₃ [(OCF ₂ CF ₂ ) _p- (OCF ₂ ) _q ] -OCF ₃ having a number average molecular weight of 6,500, p = 1 to 66, q = 1 to 91, n-hexadecane contact angle of 64 degrees. ] Was dissolved in 98 g of perfluorooctane to obtain an oil-repellent composition. The obtained oil-repellent composition is applied to a washed SUS plate using a spin coating method at 500 rpm for 20 seconds, and heat-treated at 120 ° C. for 60 minutes to obtain a test plate having an oil-repellent film. It was. The test plate was evaluated for initial oil repellency and oil repellency. The results are shown in Table 1.

[Comparative Example 1]
A solution in which 2.0 g of the polymer A was dissolved in 98 g of perfluorooctane was obtained. Using the solution, the same treatment as in Example 1 was performed to obtain a test plate. The test plate was evaluated for initial oil repellency and oil repellency. The results are shown in Table 1.

[Comparative Example 2]
1.4 g of polymer A, perfluoropolyether [CF ₃ [(OCF ₂ CF ₂ ) _p ] -OCF ₃ , number average molecular weight 2,000, p (average) = 16, contact angle of n-hexadecane 64 degrees. ] Was dissolved in 98 g of perfluorooctane. Using the solution, the same treatment as in Example 1 was performed to obtain a test plate. The test plate was evaluated for initial oil repellency and oil repellency. The results are shown in Table 1.

In Examples 1 and 2 using the oil-repellent composition of the present invention, the initial oil repellency and oil repellency of the oil-repellent film were excellent, and the adhesion of the oil-repellent film to the substrate was sufficient.
The comparative example 1 which does not contain the perfluoropolyether which is a polymer (b) was inferior in both the initial oil repellency and oil repellency of the oil repellent film.
In Comparative Example 2 using perfluoropolyether having a low number average molecular weight, the initial oil repellency of the oil repellent film was excellent, but the oil repellency endurance was inferior.

  The oil-repellent composition of the present invention can be used for an application as an oil sealant. Further, the oil-repellent composition of the present invention is excellent in water repellency as well as oil repellency, so it can be used for various protective films such as antifouling films, water / oil repellent films for fibers, antifouling films for inkjet nozzles, and waterproofing for semiconductors. It can be used as a moisture-proof film, a protective film for semiconductor wafers, an antifouling film for antireflection materials, and the like.

Claims (6)

A polymer (a) having a fluorine-containing aliphatic ring structure in the main chain and having a carboxyl group , the number average molecular weight of which is 10,000 to 5,000,000 ;
A fluorine-containing polymer is a perfluoropolyether which the main chain does not have a fluorinated aliphatic ring structure, a number average molecular weight of 6 000 to 15 000 polymer and (b),
An oil-repellent composition containing a solvent ,
In the polymer (a), the number of carboxyl groups is 1 to 10 per number average molecular weight 10,000 to 5,000,000 of the polymer (a), and in 100 mol% of all the structural units of the polymer (a), A polymer having 20 mol% or more of a structural unit having a fluorinated alicyclic structure,
Oil-repellent composition whose content of polymer (b) is 1-50 mass parts to 100 mass parts of polymers (a) .   The polymer (a) is a polymer obtained by polymerizing a monomer having a fluorine-containing aliphatic ring structure in the presence of an initiator, and a fluorine-containing monomer having two or more polymerizable double bonds is used as an initiator. Copolymerization of a polymer obtained by cyclopolymerization in the presence of a monomer, or a monomer having a fluorine-containing aliphatic ring structure and a fluorine-containing monomer having two or more polymerizable double bonds in the presence of an initiator The oil-repellent composition according to claim 1, wherein the initiator is an initiator having a carboxyl group or a precursor group thereof in the molecule. The oil-repellent composition according to claim 2, wherein the fluorine-containing monomer having two or more polymerizable double bonds is a compound represented by the following formulas (8) to (10).

(In Formulas (8) to (10), Y ^{1 to} Y ¹⁰ , Z ^{1 to} Z ⁸ , and W ^{1 to} W ⁸ are each independently F or CF _3. )   The polymer (b) is such that the contact angle of n-hexadecane with respect to the coating film made of the polymer (b) is larger than the contact angle of n-hexadecane with respect to the coating film made of the polymer (a). The oil-repellent composition as described in any one of Claims 1-3. The oil-repellent composition according to any one of claims 1 to 4 , which is an oil sealant. An article having an oil repellent film comprising the oil repellent composition according to any one of claims 1 to 5 .