FLUORINE-CONTAINING OLIGOMER, NANO-SILICA COMPOSITE PARTICLES USING THE SAME, AND METHODS FOR PRODUCING BOTH

Abstract

Disclosed is a fluorine-containing oligomer comprising a copolymer of a fluoroalkyl alcohol (meth)acrylic acid derivative represented by the general formula:

C.sub.nF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cOCOCR═CH.sub.2  [I]

wherein R is a hydrogen atom or a methyl group, n is an integer of 1 to 6, a is an integer of 1 to 4; b is an integer of 0 to 3; and c is an integer of 1 to 3; and a (meth)acrylic acid derivative represented by the general formula:

(CH.sub.2═CRCO).sub.mR′  [II]

wherein R is a hydrogen atom or a methyl group, m is 1, 2, or 3; and when m is 1, R′ is OH group, NH.sub.2 group that is unsubstituted or mono- or di-substituted with an alkyl group having 1 to 6 carbon atoms, or a monovalent group derived from an alkylene glycol or polyalkylene glycol group containing an alkylene group having 2 or 3 carbon atoms; when m is 2 or 3, R′ is a divalent or trivalent organic group derived from a diol or triol. The copolymerization reaction is performed using a hydrocarbon-based peroxide or azo compound polymerization initiator. Also disclosed are nano-silica composite particles formed as a condensate of the fluorine-containing oligomer and an alkoxysilane with nano-silica particles.

Claims

1: Fluorine-containing oligomer comprising a copolymer of a fluoroalkyl alcohol (meth)acrylic acid derivative represented by the general formula:
C.sub.nF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cOCOCR═CH.sub.2  [I] wherein R is a hydrogen atom or a methyl group, n is an integer of 1 to 6, a is an integer of 1 to 4; b is an integer of 1 to 3; and c is an integer of 1 to 3; and a (meth)acrylic acid derivative represented by the general formula:
CH.sub.2═CRCONR.sup.1R.sup.2  [II] wherein R is a hydrogen atom or a methyl group, R.sup.1 and R.sup.2 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

2: (canceled)

3: Fluorine-containing oligomer according to claim 1, which has a number average molecular weight Mn of 5,000 or less.

4: Fluorine-containing oligomer according to claim 1, wherein 0.1 to 50 mol % of fluoroalkyl alcohol (meth)acrylic acid derivative is copolymerized.

5: Method for producing a fluorine-containing oligomer, comprising copolymerizing a fluoroalkyl alcohol (meth)acrylic acid derivative represented by the general formula:
C.sub.nF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cOCOCR═CH.sub.2  [I] wherein R is a hydrogen atom or a methyl group, n is an integer of 1 to 6, a is an integer of 1 to 4; b is an integer of 1 to 3; and c is an integer of 1 to 3; and a (meth)acrylic acid derivative represented by the general formula:
CH.sub.2═CRCONR.sup.1R.sup.2  [II] wherein R is a hydrogen atom or a methyl group, R.sup.1 and R.sup.2 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; in the presence of a hydrocarbon-based peroxide or azo compound polymerization initiator.

6. (canceled)

7: Method for producing a fluorine-containing oligomer according to claim 5, wherein 0.1 to 50 wt. % of hydrocarbon-based peroxide or azo compound polymerization initiator is used based on the weight of the monomer mixture.

8-11. (canceled)

Description

EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0019] The fluorine-containing oligomer is produced by copolymerizing a fluoroalkyl alcohol (meth)acrylic acid derivative represented by the general formula:

CnF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cOCOCR═CH.sub.2  [I] [0020] R: H or a methyl group [0021] n: 1 to 6, preferably 2 to 4 [0022] a: 1 to 4, preferably 1, [0023] b: 0 to 3, preferably 1 to 2, [0024] c: 1 to 3, preferably 1,
and a (meth)acrylic acid derivative represented by the general formula:

(CH.sub.2═CRCO).sub.mR′  [II] [0025] R: H or a methyl group [0026] m: 1, 2, or 3 [0027] R′: when m is 1, OH group, an ammonium group that is unsubstituted or substituted with an alkyl, or a monovalent group derived from an alkylene glycol or polyalkylene glycol group containing an alkylene group having 2 or 3 carbon atoms; when m is 2 or 3, a divalent or trivalent organic group derived from a diol or a triol,
in the presence of a hydrocarbon-based peroxide or azo compound polymerization initiator.

[0028] The fluoroalkyl alcohol (meth)acrylic acid derivative [I] is described in Patent Document 4, and is synthesized through the following series of steps.

[0029] First, a fluoroalkyl iodide represented by the general formula:

C.sub.nF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cI

is reacted with N-methylformamide HCONH(CH.sub.3) to form a mixture of fluoroalkyl alcohol and its formate. Then, the mixture is hydrolyzed in the presence of an acid catalyst, thereby forming a fluoroalkyl alcohol of the formula:

C.sub.nF.sub.2n+1(CH.sub.2CF.sub.2).sub.a(CF.sub.2CF.sub.2).sub.b(CH.sub.2CH.sub.2).sub.cOH.

The obtained fluoroalkyl alcohol is esterified with acrylic acid or methacrylic acid to obtain a fluoroalkyl alcohol (meth)acrylic acid derivative.
Examples of the above fluoroalkyl iodide include the following: [0030] CF.sub.3(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0031] C.sub.2F.sub.5(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0032] C.sub.2F.sub.5(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0033] C.sub.3F.sub.7(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0034] C.sub.3F.sub.7(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0035] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0036] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0037] C.sub.2F.sub.5(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0038] C.sub.2F.sub.5(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0039] C.sub.2F.sub.5(CH.sub.2CF.sub.2).sub.2(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0040] C.sub.2F.sub.5(CH.sub.2CF.sub.2).sub.2(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0041] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0042] C.sub.4F.sub.9(CH.sub.2CF.sub.2).sub.2(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2)I [0043] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2)(CH.sub.2CH.sub.2).sub.2I [0044] C.sub.4F.sub.9(CH.sub.2CF.sub.2).sub.2(CF.sub.2CF.sub.2).sub.2(CH.sub.2CH.sub.2).sub.2I

[0045] The (meth)acrylic acid derivative of the formula: (CH.sub.2═CRCO).sub.mR′ [II], which is to be copolymerized with the fluoroalkyl alcohol (meth)acrylic acid derivative [I], is, when m is 1, a compound represented by the general formula:

CH.sub.2═CRCOOH

CH.sub.2═CRCONR.sup.1R.sup.2 [0046] R.sup.1, R.sup.2: H or an alkyl group having 1 to 6 carbon atoms

CH.sub.2═CRCOR.sup.3 [0047] R.sup.3: a monovalent group derived from an alkylene glycol or polyalkylene glycol group containing an alkylene group having 2 or 3 carbon atoms.
When m is 2 or 3, R′ is a divalent organic group derived from a diol, such as the abovementioned alkylene glycol or polyalkylene glycol group, or a trivalent organic group derived from a triol, such as trimethylolpropane.

[0048] The copolymerization reaction of both derivatives is performed by a solution-polymerization method in an organic solvent, such as methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, tetrahydrofuran, ethyl acetate, chloroform, 1,2-dichloroethane, or AK-225, which is described later, in the presence of a hydrocarbon-based peroxide or azo compound polymerization initiator, such as tertiary-butyl peroxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, 2,2′-azobis(2,4-dimethylvaleronitrile), or azobis(isobutyronitrile). Such a polymerization initiator is used at a ratio of about 0.1 to 50 wt. %, preferably about 5 to 20 wt. %, based on the weight of the monomer mixture.

[0049] The amount of copolymerized fluorine-containing monomer [I] in the obtained fluorine-containing oligomer is about 0.1 to 50 mol %, preferably about 1 to 20 mol %. The oligomer has a number average molecular weight Mn of about 5,000 or less, preferably about 100 to 3,000, and has a particle diameter of 200 nm or less. The dispersibility of fluorine-containing oligomer white powder when dispersed in various solvents is also excellent, except in hydrocarbon solvents.

[0050] The thus-obtained fluorine-containing oligomer is reacted with an alkoxysilane in the presence of nano-silica particles using an alkaline or acidic catalyst, thereby forming nano-silica composite particles.

[0051] As the nano-silica particles, organosilica sol having an average particle diameter (measured by a dynamic light scattering method) of 5 to 200 nm, preferably 10 to 100 nm, and having a primary particle diameter of 40 nm or less, preferably 5 to 30 nm, even more preferably 10 to 20 nm, is used. Practically used are commercial products of Nissan Chemical Industries, Ltd., such as Methanol Silica Sol, Snowtex IPA-ST (isopropyl alcohol dispersion), Snowtex EG-ST (ethylene glycol dispersion), Snowtex MEK-ST (methyl ethyl ketone dispersion), and Snowtex MIBK-ST (methyl isobutyl ketone dispersion).

[0052] Examples of the alkoxysilane include alkoxysilanes represented by the general formula:

(R.sub.1O).sub.pSi(OR.sub.2).sub.q(R.sub.3).sub.r  [III] [0053] R.sub.1, R.sub.3: H, C.sub.1-C.sub.6 alkyl group, or an aryl group [0054] R.sub.2: C.sub.1-C.sub.6 alkyl group or an aryl group, [0055] proviso that not all of R.sub.1, R.sub.2, and R.sub.3 are aryl groups [0056] p+q+r: 4, proviso that q is not 0.
Specific examples thereof include trimethoxysilane, triethoxysilane, trimethoxymethylsilane, triethoxymethyl silane, trimethoxyphenylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and the like.

[0057] The proportion of these components are such that about 10 to 100 parts by weight, preferably about 20 to 80 parts by weight, of fluorine-containing oligomer, and about 0.1 to 100 parts by weight, preferably about 20 to 80 parts by weight, of alkoxysilane are used based on 100 parts by weight of nano-silica particles. When the amount of fluorine-containing oligomer used is less than this range, the water- and oil-repellency decreases. In contrast, when the amount of fluorine-containing oligomer used is greater than this range, dispersibility in solvents decreases.

[0058] The reaction between these components is performed in the presence of a catalytic amount of an alkaline or acidic catalyst, such as aqueous ammonia, an aqueous solution of a hydroxide of an alkali metal or alkaline earth metal (e.g., sodium hydroxide, potassium hydroxide, or calcium hydroxide), or hydrochloric acid, or sulfuric acid, at a temperature of about 0 to 100° C., preferably about 10 to 50° C., for about 0.5 to 48 hours, preferably about 1 to 10 hours.

[0059] In the nano-silica composite particles obtained from the reaction, it is considered that the fluorine-containing oligomer becomes bound to a hydroxyl group present on the surface of the nano-silica particles via a siloxane bond, or that the fluorine-containing oligomer is included in a shell having a siloxane skeleton. Therefore, the chemical and thermal stability of silica, and the excellent water- and oil-repellency, antifouling properties, etc., of the fluorine-containing oligomer are effectively exhibited. In fact, the nano-silica composite particles have the effect of reducing weight loss at 800° C. Moreover, the particle size of the nano-silica composite particles and the variation of the particle size also show small values. The nano-silica composite particles are thus formed by a condensation reaction of a fluorine-containing oligomer and a silane derivative with nano-silica particles; however, mixing of other components is allowed, as long as the object of the present invention is not impaired.

EXAMPLES

[0060] The following describes the present invention with reference to Examples.

Reference Example 1

[0061] In 50 ml of isopropanol, [0062] CF.sub.3(CF.sub.2).sub.3(CH.sub.2).sub.2OCOCH═CH.sub.2 [FAAC-4] 3.00 g [0063] CH.sub.2═CHCON(CH.sub.3).sub.2[DMAA] 27.37 g
were charged. While stirring the isopropanol solution of them, an initiator, i.e., [0064] 2,2′-azobis(2,4-dimethylvaleronitrile) 3.04 g [0065] (V-65, a product of Wako Pure Chemical Industries, Ltd.)
was added. After nitrogen was bubbled to replace the dissolved oxygen, the mixture was heated until the inner temperature reached 50° C. While maintaining this temperature, the mixture was reacted for 5 hours.

[0066] The reaction mixture was supplied in n-hexane, and the generated fluorine-containing oligomer was separated by filtration, thereby obtaining 30 g (yield: 90.0%) of white powder fluorine-containing oligomer. When the molecular weight of the fluorine-containing oligomer was measured by GPC, the number average molecular weight Mn was 801, and Mn/Mw, which indicates molecular weight distribution, was 1.74. Further, when the copolymerization ratio of the obtained fluorine-containing oligomer was measured by .sup.1H-NMR, FAAC-4: DMAA was 2:98 (mol %).

Examples 1 to 6 and Reference Examples 2 to 6

[0067] In Reference Example 1, the types and amounts (unit: g) of the fluorine-containing monomer [I] and its comonomer [II], and the amount (unit: g) of the polymerization initiator (V-65) were changed in various ways. The results shown in Table 1 (Examples) and Table 2 (Reference Examples) below were obtained. Then, Table 2 also shows the results of Reference Example 1. The Mn of fluorine-containing oligomers in which PDE 100 is copolymerized cannot be measured because they are insoluble in the GPS mobile phase.

[0068] (Fluorine-Containing Monomers) [0069] DTFAC: CF.sub.3(CF.sub.2).sub.3CH.sub.2(CF.sub.2).sub.5(CH.sub.2).sub.2OCOCH═CH.sub.2 [0070] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2).sub.2(CH.sub.2CH.sub.2)OCOCH═CH.sub.2 [0071] DTFMAC: CF.sub.3(CF.sub.2).sub.3CH.sub.2(CF.sub.2).sub.5(CH.sub.2).sub.2OCOC(CH.sub.3)═CH.sub.2 [0072] C.sub.4F.sub.9(CH.sub.2CF.sub.2)(CF.sub.2CF.sub.2).sub.2(CH.sub.2CH.sub.2)OCOC(CH.sub.3)═CH.sub.2 [0073] FAAC-6: CF.sub.3(CF.sub.2).sub.5(CH.sub.2).sub.2OCOCH═CH.sub.2 [0074] FAAC-8: CF.sub.3(CF.sub.2).sub.7(CH.sub.2).sub.2OCOCH═CH.sub.2

[0075] (Comonomers) [0076] PDE 100: Diethylene glycol dimethacrylate [0077] ACA: Acrylic acid

[0078] Tables 1 and 2 also show the particle diameter (unit: nm) of the produced fluorine-containing oligomer white powders measured by a dynamic light scattering method, the particle diameter distribution, and the dispersibility of the powders. The dispersibility was visually observed when 1 wt. % of each powder was dispersed in various solvents, and evaluated according to the following evaluation criteria. Regarding the solvent dispersibility, dispersibility in water, methanol, ethanol, isopropanol, and dimethylsulfoxide is ◯, while dispersibility in toluene and n-hexane is X; therefore, their descriptions are omitted.

[0079] ◯: Uniformly dispersed, and transparent dispersion

[0080] Δ: Slightly dispersed, and cloudy dispersion

[0081] X: Not dispersed, but precipitated in dispersion medium

TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 [Monomer, initiator] Fluorine- containing monomer DTFAC 3.10 3.02 3.31 — 3.27 — DTFMAC — — — 3.21 — 3.04 Comonomer DMAA 27.22 27.14 — — — — PDE 100 — 5.04 — — 5.21 5.04 ACA — — 27.45 27.09 27.06 27.04 Polymerization initiator V-65 3.07 3.06 3.02 3.01 3.06 3.04 [F-containing oligomer] Yield (%) 99.3 107.5 112.7 93.8 105.8 95.2 Mn 2107 — 1142 667 — — Mn/Mw 1.09 — 1.00 1.82 — — Copolymerization ratio (mol %) Fluorine- 7 3 1 16 1 4 containing monomer DMAA 93 93 — — — — PDE100 — 4 — — 5 2 ACA — — 99 84 94 94 Particle diameter Average value 35.4 41.1 41.8 126 54.6 33.0 Average value± 8.0 11.7 3.8 13.1 12.4 9.7 Solvent dispersibility Acetone ◯ ◯ Δ Δ ◯ Δ Tetrahydrofuran ◯ ◯ ◯ ◯ ◯ ◯ Ethyl acetate ◯ ◯ Δ Δ X Δ Chloroform ◯ ◯ Δ Δ X Δ ClCH.sub.2CH.sub.2Cl ◯ ◯ Δ Δ X Δ AK-225 ◯ ◯ Δ Δ X Δ

TABLE-US-00002 TABLE 2 Reference Example 1 2 3 4 5 6 [Monomer, initiator] Fluorine- containing monomer FAAC-4 3.00 — — — — — FAAC-6 — 3.02 — 3.05 — — FAAC-8 — — 3.08 — 3.07 3.17 Comonomer DMAA 27.37 27.07 27.01 27.05 — — PDE 100 — — — 5.0 — 5.07 ACA — — — — 27.12 27.04 Polymerization initiator V-65 3.04 3.11 3.27 3.00 3.33 3.20 [F-containing oligomer] Yield (%) 90.0 87.3 77.8 71.0 106.5 97.1 Mn 801 2078 2202 — 1032 — Mn/Mw 1.74 1.01 1.03 — 1.02 — Copolymerization ratio (mol %) Fluorine- 2 13 6 3 3 5 containing monomer DMAA 98 87 94 93 — — PDE100 — — — 4 — 12 ACA — — — — 97 83 Particle diameter Average value 64.5 87.0 106 17.2 41.9 76.7 Average value± 9.8 11.4 17.6 2.4 4.2 9.8 Solvent dispersibility Acetone ◯ ◯ ◯ ◯ Δ ◯ Tetrahydrofuran ◯ ◯ ◯ ◯ ◯ ◯ Ethyl acetate ◯ ◯ ◯ ◯ X Δ Chloroform ◯ ◯ ◯ ◯ X X ClCH.sub.2CH.sub.2Cl ◯ ◯ ◯ ◯ Δ X AK-225 ◯ Δ ◯ ◯ X Δ Note 1) AK-225: a product of AGC; an amount mixture of 1,1-dichloro-2,2,3,3,3-pentafluoropropane and 1,3-dichloro-1,2,2,3,3-pentafluoropropane Note 2) Fluorine-containing oligomers with a yield of 100% or more are considered to contain the solvent

Reference Example 11

[0082] To 0.25 g of the fluorine-containing oligomer (FAAC-8-DMAA copolymer) obtained in Reference Example 3, 1.67 g (0.50 g as nano-silica) of silica sol (Methanol Silica Sol, a product of Nissan Chemical Industries, Ltd.; nano-silica content: 30 wt. %, average particle diameter: 11 nm) and 20 ml of methanol were added. Further, 0.25 ml of tetraethoxysilane (a product of Tokyo Chemical Industry Co., Ltd.; density: 0.93 g/ml) and 0.25 ml of 25 wt. % aqueous ammonium were added under stirring conditions, and the mixture was reacted for 5 hours.

[0083] The methanol and aqueous ammonium were removed from the reaction mixture, which was a white solution, using an evaporator, and the taken white powder was redispersed in 10 ml of methanol overnight. After centrifugation, the resultant was rinsed with methanol, and the obtained powder was dried in an oven at 70° C., and then vacuum dried at 50° C. As a result, 0.507 g (yield: 62%) of white powder, which was nano-silica composite particles, was obtained.

[0084] The particle diameter of the obtained white powder was measured by a dynamic light scattering (DLS) method in a state where 1 g of white powder was dispersed in 1 L of methanol. In addition, the weight loss of the powder was measured in the following manner. That is, the rate of weight loss (percentage of reduced weight to initial weight) when the powder was heated to 800° C. at a heating rate of 10° C./min was measured using TGA (TG-DTA2000SA, produced by Bruker AXS).

Reference Example 12

[0085] In Reference Example 11, the same amount (0.25 g) of the fluorine-containing oligomer (FAAC-8-ACA copolymer oligomer) obtained in Reference Example 5 was used as the fluorine-containing oligomer.

Example 11

[0086] In Reference Example 11, the same amount (0.25 g) of the fluorine-containing oligomer (DTFAC-DMAA copolymer oligomer) obtained in Example 1 was used as the fluorine-containing oligomer.

Example 12

[0087] In Reference Example 11, the same amount (0.25 g) of the fluorine-containing oligomer (DTFAC-ACA copolymer oligomer) obtained in Example 3 was used as the fluorine-containing oligomer.

Example 13

[0088] In Reference Example 11, the same amount (0.25 g) of the fluorine-containing oligomer (DTFMAC-ACA copolymer oligomer) obtained in Example 4 was used as the fluorine-containing oligomer.

[0089] Table 3 below shows the measurement results obtained in Reference Examples 11 and 12, and Examples 11 to 13, together with the generation amount and yield of nano-silica composite particles.

TABLE-US-00003 TABLE 3 Nano-silica composite particles Generation Particle Weight Example amount (g) Yield (%) diameter (nm) loss (%) Ref. Ex. 11 0.507 62 49.6 ± 12.4 19 Ref. Ex. 12 0.572 70 45.3 ± 10.4 8 Ex. 11 0.646 79 51.9 ± 14.4 10 Ex. 12 0.507 62 30.9 ± 6.4  20 Ex. 13 0.580 71 41.2 ± 18.0 13