JPWO2018159307A1 - Fluoropolymer, method for producing cured product thereof, and light emitting device - Google Patents

Abstract

Provided are a method for producing a fluorinated polymer which is heat-curable and has both melt moldability and heat resistance and UV resistance, a method for producing a cured product of the fluorinated polymer, and a light emitting device using the same. The fluoropolymer includes a unit represented by the following formula (1) and a unit represented by the following formula (2). (In the formula (1), Rf1 is a fluoroalkylene group or a fluoroalkylene group having 2 or more carbon atoms having an etheric oxygen atom between carbon and carbon atoms, and R1 and R2 are each independently In formula (2), X1, X2, and X3 are each independently a fluorine atom or a hydrogen atom, and two Q2s are each independently a single bond or an etheric oxygen atom, and Rf2 Is a fluoroalkylene group having 1 to 6 carbon atoms or a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon-carbon atoms.)

Description

  The present invention relates to a fluoropolymer, a method for producing a cured product thereof, and a light emitting device.

  2. Description of the Related Art In recent years, white LEDs (Light Emitting Diodes) have been put into practical use as light sources for highly efficient illumination, replacing incandescent lamps and fluorescent lamps. Ultraviolet (UV) LEDs have also been increased in output and replaced with mercury lamps, and have begun to be used in various industrial processes. In an LED lamp using a white LED or a UV LED, the LED element is sealed (molded) with a translucent resin such as a silicone resin in order to protect the LED element from external physical and chemical actions. However, in a UVLED, the translucent resin is deteriorated by ultraviolet rays and heat emitted from the LED. Also, in the case of white LEDs, for example, in an LED lamp requiring a high output, such as a headlamp of an automobile or outdoor lighting, the light-transmitting resin for sealing the LED element deteriorates. For this reason, the LED element is protected using a glass cap or lid without using a resin, and there is a problem that the structure of the LED lamp is complicated and the cost is high.

A curable fluoropolymer having a carboxylic acid alkyl ester group, for example, a COOCH ₃ group is proposed as a light-transmitting resin having high heat resistance and light resistance for encapsulating high-power LEDs such as white LEDs and UV LEDs. (For example, see Patent Document 1). The curable fluoropolymer is cured by irradiation with active energy rays to obtain a cured product having excellent stability and ultraviolet light transmittance.

WO 2015/098773

  However, according to the study of the present inventor, the fluoropolymer described in Patent Document 1 requires ultraviolet (UV) irradiation for curing, and therefore, a shadow portion where UV is not irradiated in the LED element structure. If there is, there is a problem that insufficient curing occurs in the portion.

  An object of the present invention is to provide a fluorine-containing polymer which is heat-curable, has good melt moldability, gives a cured product having high heat resistance and UV resistance and high transparency, and a method for producing the cured product.

The present invention provides a fluoropolymer having the following constitutions [1] to [11], a method for producing a cured product of the fluoropolymer, a light-emitting element, and a light-emitting device.
[1] A fluoropolymer containing a unit represented by the following formula (1) and a unit represented by the following formula (2).

（式（１）中、Ｒ^ｆ１は、フルオロアルキレン基、または炭素−炭素原子間にエーテル性酸素原子を有する炭素数２以上のフルオロアルキレン基であり、Ｒ^１、Ｒ^２は、それぞれ独立に、水素原子またはアルキル基である。）

(In the formula (1), R ^f1 is a fluoroalkylene group or a fluoroalkylene group having 2 or more carbon atoms having an etheric oxygen atom between carbon and carbon atoms, and R ¹ and R ² are each independently: It is a hydrogen atom or an alkyl group.)

（式（２）中、Ｘ^１、Ｘ^２、Ｘ^３はそれぞれ独立にフッ素原子または水素原子であり、２つのＱ^２はそれぞれ独立に単結合またはエーテル性酸素原子であり、Ｒ^ｆ２は炭素数１〜６のフルオロアルキレン基、または炭素−炭素原子間にエーテル性酸素原子を有する炭素数２〜２５のフルオロアルキレン基である。）
［２］式（１）で表される単位の少なくとも一部が、−［ＣＦ_２−ＣＦ（Ｏ（ＣＦ_２）_３ＣＯＮＨＮＨ_２）］−である、［１］に記載の含フッ素重合体。
［３］さらに、フルオロエチレン由来の単位を含む、［１］または［２］に記載の含フッ素重合体。

(In formula (2), X ¹ , X ² , and X ³ are each independently a fluorine atom or a hydrogen atom, two Q ² are each independently a single bond or an etheric oxygen atom, and R ^f2 is a carbon atom. A fluoroalkylene group having 1 to 6 carbon atoms or a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon-carbon atoms.)
At least a portion of the units represented by formula [2] _{(1), - [CF 2 -CF (O} (CF 2) 3 CONHNH 2)] - is a fluorine-containing polymer according to [1].
[3] The fluorinated polymer according to [1] or [2], further comprising a unit derived from fluoroethylene.

[4] The fluorinated polymer according to any one of [1] to [3], further comprising a unit represented by the following formula (3) (excluding units derived from fluoroethylene).
-[CX ⁴ X ⁵ -CY ¹ Y ² ] -... (3)
(In the formula (3), X ⁴ and X ⁵ are each independently a hydrogen atom, a fluorine atom or a chlorine atom;
Y ¹ is a hydrogen atom, a fluorine atom or a chlorine atom;
Y ² represents a hydrogen atom, a fluoroalkyl group, a fluoroalkyl group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms, a fluoroalkoxy group, or a carbon atom having an etheric oxygen atom between carbon-carbon atoms. It is a fluoroalkoxy group of two or more. )

[5] The proportion of the unit represented by the formula (1) is 0.1 to 20 mol% with respect to the total of the units contained in the fluoropolymer, and the proportion of the unit represented by the formula (2) is The fluorine-containing polymer according to any one of [1] to [4], which has a content of 0.05 to 3 mol%.
[6] The proportion of the unit represented by the formula (1) is 0.1 to 5 mol% with respect to the total of the units contained in the fluoropolymer, and the proportion of the unit represented by the formula (2) is The fluorine-containing polymer according to any one of [1] to [4], which has a content of 0.05 to 3 mol%.
[7] The fluorinated polymer according to any one of [1] to [6], having a mass average molecular weight of 3,000 to 100,000.
[8] The fluoropolymer according to any one of [1] to [6], having a mass average molecular weight of 5,000 to 100,000.

[9] A method for producing a cured product of a fluoropolymer, comprising heating the fluoropolymer according to any one of [1] to [8] at 150 to 300 ° C.
[10] A light-emitting device comprising a light-emitting element and a cured product of the fluoropolymer according to any one of [1] to [8].
[11] The light emitting device according to [10], wherein the light emitting element is a white LED or an ultraviolet LED.

  According to the present invention, it is possible to provide a method for producing a fluorinated polymer and a cured product of a fluorinated polymer which can be cured by heat and have good melt moldability, and provide a cured product having high heat resistance and UV resistance and high transparency. .

  Hereinafter, an embodiment of the present invention will be described. Note that the present invention is not construed as being limited to the following description.

[Meaning of terms in this specification]
The compound represented by the formula (a) may be referred to as a compound (a). The same applies to compounds represented by other formulas. The unit represented by the formula (b) may be referred to as a unit (b). Units represented by other formulas are described in the same manner.

  “Translucent sealing” means sealing having both a function of transmitting light and a sealing function.

  The “unit” in the polymer means a portion derived from the monomer formed by polymerization of the monomer. A unit derived from a monomer may be simply referred to as a monomer unit.

“Fluoroethylene” refers to a compound in which 0 to 3 fluorine atoms of tetrafluoroethylene (CF ₂ ＣＦCF ₂ ) are substituted with a hydrogen atom or a halogen atom other than fluorine (eg, chlorine, bromine, iodine). I do.

  Groups having a carbon atom chain such as an alkyl group, a fluoroalkyl group, a fluoroalkylene group, a fluoroalkoxy group, and a fluoroalkenyl group may be linear or branched.

“Fluoroalkyl group” refers to a group in which one or more hydrogen atoms of an alkyl group have been replaced by fluorine atoms. The ratio of the fluorine atom in the fluoroalkyl group is represented by (the number of fluorine atoms in the fluoroalkyl group) / (the number of hydrogen atoms in the alkyl group having the same number of carbon atoms as the fluoroalkyl group) × 100 (%). Is preferably 50% or more, more preferably 100%, that is, a perfluoroalkyl group. The same applies to a fluoroalkylene group and a fluoroalkoxy group, and a perfluoroalkylene group and a perfluoroalkoxy group are preferred.
“Curing” means curing by crosslinking, unless otherwise specified.

[Fluorine-containing polymer]
The fluoropolymer of this embodiment includes a unit represented by the following formula (1) and a unit represented by the following formula (2).

(In the formula (1), R ¹ and R ² are each independently a hydrogen atom or an alkyl group;
R ^f1 is a fluoroalkylene group or a fluoroalkylene group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms. )

(In formula (2), X ¹ , X ² , and X ³ are each independently a fluorine atom or a hydrogen atom, two Q ² are each independently a single bond or an etheric oxygen atom, and R ^f2 is a carbon atom. A fluoroalkylene group having 1 to 6 carbon atoms or a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon-carbon atoms.)

The present inventors have fluoropolymer having units (1) and unit (2) is, -CONHNH ₂ with each other between the molecules found in the new be crosslinked by the reaction by heating. The fluorine-containing polymer of the present embodiment, in order to crosslink only -CONHNH _2, it is possible to cure the fluoropolymer in an amount of less bridging group. Therefore, the cured product is excellent in transparency and heat resistance, and excellent in light resistance, particularly UV resistance. Furthermore, since the fluoropolymer of this embodiment can be cured with a small amount of crosslinking groups by containing the unit (1) and the unit (2), the melt fluidity is impaired during LED molding. It is possible to suppress foaming without any problems, and it is also excellent in melt moldability.

The present inventors have investigated a fluoropolymer having a -CONHNH ₂ and -COOCH ₃ above. In the fluoropolymer, it is considered that a crosslinking reaction represented by the following formula (11) occurs by heating.
-CONHNH ₂ + -COOCH ₃ → -CONHNHCO- (11)

Although the cross-linking reaction mechanism of the fluoropolymer of the present embodiment is not clear, it is considered as follows. For example, as in the fluorine-containing polymer of the present embodiment, a compound having -CONHNH ₂ , for example, phthalic dihydrazide, is oxidatively coupled with an oxidizing agent in a polar solvent as shown in the following formula (12). Thus, it is known that poly (diacylhydrazine) can be obtained.

On the other hand, the fluoropolymer having the fluoroacyl hydrazide structure of the present embodiment in the side chain can be cured by heating in air. In addition, a cured product can be obtained by heating the fluoropolymer of the present invention even in an N ₂ atmosphere, for example, by heating to 150 ° C. or higher or irradiating with an active energy ray, without using an oxidizing agent. A cured product is obtained. As a cross-linking reaction mechanism of the fluoropolymer, as shown by the following formula (13), it is considered that hydrazide is thermally decomposed and coupled to form a diacyl hydrazine without involving an oxidation reaction. Further, as shown by the following formula (14), there is a possibility that tetrazine is formed by a dehydration cyclization reaction. When a cured product is obtained from the fluorinated polymer of the present embodiment, heating in an N ₂ atmosphere is preferable in that the cured product is less colored than heating in air.

2-CONHNH ₂ → -CONHNHCO- (13)

  Hereinafter, each unit contained in the fluoropolymer of the present embodiment will be described.

<Unit (1)>
The unit (1) is a unit represented by the following formula (1).

In the unit (1), R ¹ and R ² are each independently a hydrogen atom or an alkyl group, and R ^f1 is a fluoroalkylene group or a carbon number of 2 or more having an etheric oxygen atom between carbon-carbon atoms. Is a fluoroalkylene group.

When R ^f1 in the unit (1) is a fluoroalkylene group, the number of carbon atoms is preferably from 1 to 6, particularly preferably from 1 to 4. When the number of carbon atoms is 3 or more, R ^f1 preferably has a linear structure from the viewpoint of excellent thermal stability. The fluoroalkylene group is preferably a perfluoroalkylene group from the viewpoint of excellent thermal stability. That is, R ^f1 is preferably a C 1-6 perfluoroalkylene group, particularly preferably a C 1-4 perfluoroalkylene group.

In the unit (1), when R ^f1 is a fluoroalkylene group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms, R ^f1 preferably has 2 to 10 carbon atoms, and 2 to 6 carbon atoms. Particularly preferred. When the number of carbon atoms is 3 or more, R ^f1 preferably has a linear structure from the viewpoint of excellent thermal stability. The fluoroalkylene group is preferably a perfluoroalkylene group from the viewpoint of excellent thermal stability. That is, R ^f1 is preferably a perfluoroalkylene group having 2 to 10 carbon atoms having an etheric oxygen atom between carbon-carbon atoms, and a perfluoroalkylene group having 2 to 6 carbon atoms having an etheric oxygen atom between carbon-carbon atoms. Alkylene groups are particularly preferred.

R ¹ and R ² are preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, and particularly preferably a hydrogen atom, from the viewpoint of excellent heat curability.

Specific examples of the unit (1) include the following units.
-[CF ₂ -CF (O (CF ₂ ) ₂ CONHNH ₂ )]-,
_{- [CF 2 -CF (O (} CF 2) 2 CON (CH 3) NH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 2 CONHNHCH 3)] -,
_{- [CF 2 -CF (O (} CF 2) 3 CONHNH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 3 CON (CH 3) NH 2)] -,
-[CF ₂ -CF (O (CF ₂ ) ₃ CONHNHCH ₃ )]-,
-[CF ₂ -CF (O (CF ₂ ) ₄ CONHNH ₂ )]-,
_{- [CF 2 -CF (O (} CF 2) 4 CON (CH 3) NH 2)] -
_{- [CF 2 -CF (O (} CF 2) 4 CONHNHCH 3)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 2 CONHNH 2)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 2 CON (CH 3) NH 2)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 2 CONHNHCH 3)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 3 CONHNH 2)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 3 CON (CH 3) NH 2)] -,
_{- [CF 2 -CF (OCF 2} CF (CF 3) O (CF 2) 3 CONHNHCH 3)] -
_{- [CF 2 -CF (O (} CF 2) 3 O (CF 2) 2 CONHNH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 3 O (CF 2) 2 CON (CH 3) NH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 3 O (CF 2) 2 CONHNHCH 3)] -,
_{- [CF 2 -CF (O (} CF 2) 2 O (CF 2) 2 CONHNH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 2 O (CF 2) 2 CON (CH 3) NH 2)] -,
_{- [CF 2 -CF (O (} CF 2) 2 O (CF 2) 2 CONHNHCH 3)] -.
From easy availability point, the unit (1) _{is, - [CF 2 -CF (O} (CF 2) 3 CONHNH 2)] - are particularly preferred.

  The fluoropolymer may contain one type of unit (1) alone or may contain two or more types of unit (1).

<Unit (2)>
The unit (2) is a unit represented by the following formula (2).

In the unit (2), X ¹ , X ² , and X ³ are each independently a fluorine atom or a hydrogen atom, two Q ² are each independently a single bond or an etheric oxygen atom, and R ^f2 has 1 carbon atom. Or a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon-carbon atoms. Two X ¹ in the unit (2) may be the same or different. The same applies to two X ² and two X ³ . The two Q ² 'in the unit (2) may be the same or different.

In the unit (2), X ¹ , X ² and X ³ are each preferably a fluorine atom, or all are preferably a hydrogen atom. When X ¹ , X ² , and X ³ are all fluorine atoms, two Q ² are preferably etheric oxygen atoms, and when X ¹ , X ² , and X ³ are all hydrogen atoms, Preferably, each of the two Q ² is a single bond.

In the unit (2), when R ^f2 is a fluoroalkylene group having 1 to 6 carbon atoms, the number of carbon atoms is preferably 2 or more. When the number of carbon atoms is 3 or more, R ^f2 preferably has a linear structure from the viewpoint of excellent thermal stability. The fluoroalkylene group is preferably a perfluoroalkylene group from the viewpoint of excellent thermal stability. That is, as R ^f2 , a perfluoroalkylene group having 1 to 6 carbon atoms is preferable, and a perfluoroalkylene group having 2 or more carbon atoms is more preferable.

When R ^f2 is a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon and carbon atoms, the carbon number is preferably 2 to 10, and particularly preferably 2 to 6. When the number of carbon atoms is 3 or more, R ^f2 preferably has a linear structure from the viewpoint of excellent thermal stability. The fluoroalkylene group is preferably a perfluoroalkylene group from the viewpoint of excellent thermal stability. That is, R ^f2 is preferably a perfluoroalkylene group having 2 to 10 carbon atoms having an etheric oxygen atom between carbon-carbon atoms, and a perfluoroalkylene group having 2 to 6 carbon atoms having an etheric oxygen atom between carbon-carbon atoms. Alkylene groups are more preferred. Carbon - perfluoroalkylene group having 2 to 6 carbon atoms and having an etheric oxygen atom between carbon _{atoms, - (CF 2 O) -} , - (CF 2 CF 2 O) -, - (CF 2 CF (CF 3) O) -, and _{- (CF 2 CF 2 CF 2} O) - preferably comprises one or more perfluoropolyether units represented by.

As specific examples of the unit (2), X ¹ , X ² , and X ³ are all fluorine atoms, two Q ² are all etheric oxygen atoms, and R ^f2 is — (CF ₂ ) ₂ —. _{, - (CF 2) 3 -} , - (CF 2) 4 -, - (CF 2) 6 -, - (CF 2) 4 OCF (CF 3) CF 2 -, - (CF 2) 2 OCF (CF 3 _{) CF 2 -, - (CF} 2 CF 2 O) 2 -, - CF 2 O (CF 2 CF 2 O) 2 - or _{-CF 2 CF (CF 3) O} (CF 2) 2 OCF (CF 3) CF ₂ - is a ^unit, both the X ^1, X 2, ^{X 3} is a hydrogen atom, two ^{Q 2} are both single ^{bonds, R f2} is _{- (CF 2) 2 -,} - (CF 2) _A unit which is 4- or-(CF ₂ ) _6- is exemplified.

As the unit (2), a unit represented by the following formulas (21) and (22) is particularly preferable in terms of availability.

  The unit (2) can be formed by polymerizing a fluorine-containing monomer having two polymerizable unsaturated bonds represented by the following formula (2a). Hereinafter, the fluorine-containing monomer represented by the formula (2a) is also referred to as a monomer (2a).

^{X 1 X 2 C = CX 3} -Q 2 -R f2 -Q 2 -CX 3 = CX 1 X 2 (2a)
In the formula (2a), X ¹ , X ² , X ³ , Q ² and R ^f2 are as defined in the formula (2), and the examples and the preferred ranges are also the same.

Specific examples of the monomer (2a) include the following monomers.
CF ₂ ＣＦCFO (CF ₂ ) ₂ OCF = CF ₂ ,
CF ₂ ＣＦCFO (CF ₂ ) ₃ OCF = CF ₂ ,
CF ₂ ＣＦCFO (CF ₂ ) ₄ OCF = CF ₂ ,
CF ₂ ＣＦCFO (CF ₂ ) ₆ OCF = CF ₂ ,
_{CF 2 = CFO (CF 2)} 4 OCF (CF 3) CF 2 OCF = CF 2,
_{CF 2 = CFO (CF 2)} 2 OCF (CF 3) CF 2 OCF = CF 2,
CF ₂ ＣＦCFO (CF ₂ CF ₂ O) ₂ OCF = CF ₂ ,
_{CF 2 = CFOCF 2 O (CF} 2 CF 2 O) 2 OCF = CF 2,
_{CF 2 = CFOCF 2 CF (CF} 3) O (CF 2) 2 OCF (CF 3) CF 2 OCF = CF 2,
_{CH 2 = CH- (CF 2)} 2 -CH = CH 2,
_{CH 2 = CH- (CF 2)} 4 -CH = CH 2,
_{CH 2 = CH- (CF 2)} 6 -CH = CH 2.

<More units>
The fluoropolymer of this embodiment may further have a fluoroethylene unit and a unit (3) described later.

(Fluoroethylene unit)
Specific examples of the fluoroethylene units, tetrafluoroethylene _{(CF 2 = CF 2) (} TFE), trifluoroethylene _{(CF 2 = CHF) (TrFE} ), chlorotrifluoroethylene (CFCl = _CF 2), vinylidene fluoride (CF ₂ ＣＨCH ₂ ). As the fluoroethylene unit, a TFE unit, a TrFE unit, and a chlorotrifluoroethylene unit are preferable from the viewpoint of excellent light resistance. As the fluoroethylene unit, a TFE unit is preferable from the viewpoint of excellent heat resistance. As the fluoroethylene unit, TFE is used because a highly polar —CONR ¹ NR ² H group is easily present at the interface, and the cured product of the fluorinated polymer is excellent in adhesiveness to a substrate and wettability. Units are particularly preferred. As the fluoroethylene unit, a TrFE unit or a chlorotrifluoroethylene unit is particularly preferable because the fluoropolymer has less crystallinity than the TFE unit, does not easily cause light scattering, and has high transparency. As the fluoroethylene unit, a TrFE unit is particularly preferable because of its excellent solubility in various organic solvents. The above-mentioned wettability means that the surface tension of the fluorine-containing polymer is low, so that the fluorine-containing polymer easily spreads on the substrate.

  The fluoropolymer may contain one type of fluoroethylene unit alone or may contain two or more types of fluoroethylene units.

(Unit (3))
The unit (3) is a unit represented by the following formula (3) (however, excluding a fluoroethylene unit).
-[CX ⁴ X ⁵ -CY ¹ Y ² ] -... (3)

In the formula (3), X ⁴ and X ⁵ are each independently a hydrogen atom, a fluorine atom or a chlorine atom, Y ¹ is a hydrogen atom, a fluorine atom or a chlorine atom, Y ² is a hydrogen atom, A fluoroalkyl group, a fluoroalkyl group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms, a fluoroalkoxy group, a fluoroalkoxy group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms, is there.

The carbon number of the fluoroalkyl group in Y ² is preferably from 1 to 15, and particularly preferably from 1 to 6. The fluoroalkyl group is preferably a perfluoroalkyl group, more preferably a C 1-6 perfluoroalkyl group, and particularly preferably —CF ₃ , from the viewpoint of excellent thermal stability. The carbon number of the fluoroalkyl group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms in Y ² is preferably 2 to 15, and particularly preferably 2 to 6. From the viewpoint of excellent thermal stability, a perfluoroalkyl group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms is preferable, and a perfluoroalkyl group having 2 to 6 carbon atoms having an etheric oxygen atom between carbon-carbon atoms is preferable. Alkyl groups are particularly preferred.

The carbon number of the fluoroalkoxy group in Y ² is preferably from 1 to 15, particularly preferably from 1 to 6. Fluoroalkoxy group, from the viewpoint of excellent thermal stability, preferably perfluoroalkoxy group having 1 to 6 carbon _{atoms, -OCF 3, -OCF 2 CF 3} , -O (CF 2) 2 CF 3, -O (CF 2 ) ₃ CF ₃ is particularly preferred. In Y ^2, carbon - carbon number of fluoroalkoxy group having 2 or more carbon atoms having carbon atoms between the etheric oxygen atom is preferably 2 to 15, 2 to 6 is particularly preferred. As the fluoroalkoxy group, from the viewpoint of excellent thermal stability, a perfluoroalkoxy group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms is preferable, and a carbon atom having an etheric oxygen atom between carbon-carbon atoms is preferable. more preferably perfluoroalkoxy group having _{2~6, -OCF 2 CF (CF 3} ) O (CF 2) 2 CF 3 is particularly preferred.

Specific examples of the unit (3) include the following units.
_{- [CH 2 -CH 2] -} , - [CF 2 -CF (CF 3)] -, - [CH 2 -CF (CF 3)] -, - [CF 2 -CF (OCF 3)] -, - _{[CF 2 -CF (OCF 2 CF} 3)] -, - [CF 2 -CF (O (CF 2) 2 CF 3)] -, - [CF 2 -CF (O (CF 2) 3 CF 3)] _{-, - [CF 2 -CF (} OCF 2 CF (CF 3) O (CF 2) 2 CF 3)] -, - [CF 2 -CF (OCF 2 CF 2 OCF 2 CF 2 OCF 2 CF 3)] - .

From the viewpoint that the glass transition temperature of the fluorinated polymer is low, excellent in fluidity, excellent in moldability, and in curing the fluorinated polymer, the motility is high and the cross-linking reaction between molecules is easy to proceed. _{(3), - [CH 2 -CH 2]} -, - [CF 2 -CF (CF 3)] -, - [CF 2 -CF (OCF 3)] -, - [CF 2 -CF (O ( _{CF 2) 2 CF 3)]} -, - [CF 2 -CF (OCF 2 CF (CF 3) O (CF 2) 2 CF 3)] - or _{- [CF 2 -CF (OCF 2} CF 2 OCF 2 CF ₂ OCF ₂ CF _3)] - is preferred.

  The fluorinated polymer may contain one kind of the unit (3) alone or may contain two or more kinds of the unit (3).

The unit (3) can be formed by polymerizing the compound (3a) as a monomer.
CX ⁴ X ⁵ = CY ¹ Y ² (3a)
In formula (3a), X ⁴ , X ⁵ , Y ¹ and Y ² are as defined in formula (3), and the examples and preferred ranges are also the same.

<Embodiment of preferred fluoropolymer>
As long as the effects of the present invention are not impaired, the fluoropolymer of the present embodiment may include, for example, -COOR in addition to the unit (1), the unit (2) and the optionally contained fluoroethylene unit and the unit (3). ⁷ , a unit having a group represented by —C (O) NR ⁸ OR ⁹ (R ⁷ is an alkyl group, and R ⁸ and R ⁹ are each independently a hydrogen atom or an alkyl group). . It is preferable that the fluoropolymer of the present embodiment comprises only the unit (1), the unit (2), and the fluoroethylene unit and the unit (3) optionally contained. From the viewpoint of improving the curability, the number of units (1) contained in the fluoropolymer is preferably 3 or more per molecule of the fluoropolymer.

  The ratio of the unit (1) in all units of the fluoropolymer of the present embodiment is preferably 0.1 mol% or more. The ratio of the unit (1) is preferably 20 mol% or less, more preferably 10 mol% or less. The proportion of the unit (1) in all the units of the fluoropolymer is adjusted according to the molecular weight of the fluoropolymer so that the number per one fluoropolymer molecule becomes the preferable number (3 or more). can do. For example, the ratio of the unit (1) is increased when the molecular weight of the fluoropolymer is small, and is decreased when the molecular weight is large. Specifically, when the molecular weight of the fluoropolymer is about 3,000 to less than 10,000, the ratio of the unit (1) can be 1 to 10 mol% in all units of the fluoropolymer. When the molecular weight of the fluoropolymer is relatively large, about 10,000 to 10,000, the ratio of the unit (1) is preferably 0.1 to 5 mol%, more preferably 0.5 to 2 mol%, and -1.5 mol% is particularly preferred.

When the proportion of the unit (1) is lower than the lower limit value of the range, there is a tendency that the fluorine-containing polymer is liable to occur heat curing even without containing -COOCH _3, insoluble cured product in a solvent is obtained. When the proportion of the unit (1) is at most the upper limit of the above range, coloring and foaming when the fluoropolymer is cured by heat will be suppressed, and a transparent cured product will be obtained.

  In all the units of the fluoropolymer of the present embodiment, the ratio of the unit (2) is preferably 0.05 to 3 mol%, more preferably 0.1 to 1 mol%. Since the fluoropolymer contains the unit (2), the content ratio of the unit (1) can be reduced. For this reason, coloring and foaming during thermal curing can be suppressed, and thus the fluoropolymer of the present embodiment is particularly suitable as an LED sealing material.

  When the fluoropolymer of this embodiment has fluoroethylene units, the proportion of fluoroethylene units in all units is preferably from 50 to 90 mol%, more preferably from 60 to 80 mol%. In particular, when the fluoroethylene unit is a TFE unit, the ratio is preferably 50 to 70 mol%. If the lower limit is not less than the lower limit, in addition to the light resistance, various properties based on the fluoroethylene unit (for example, when the fluoroethylene unit is a TFE unit, heat resistance, adhesiveness to a substrate, wettability, and the like are easily improved). When the value is equal to or less than the upper limit, light scattering due to crystallinity is suppressed, and when the fluoropolymer is used for sealing a UV-LED, the transmittance of UV light is high, and the output of the UV-LED can be secured.

The content of the unit (1), the unit (3) and the fluoroethylene unit in the fluoropolymer can be calculated by ¹⁹ F-NMR and ¹ H-NMR measurements. Since it is difficult to measure the content of the unit (2), the units (1) and (2) have a common structure CF ₂ ＣＦCFO—CF ₂ — involved in polymerization. Are considered to be substantially the same, the content of the unit (2) is determined from the charged ratio of the monomer (the monomer (1a) described later) and the monomer (2a) forming the unit (1). It is estimated using the content of the unit (1) in the fluoropolymer.

(Molecular weight)
The weight average molecular weight of the fluoropolymer of the present embodiment is preferably from 3,000 to 100,000, and more preferably from 5,000 to 100,000. The weight average molecular weight is more preferably from 10,000 to 50,000, particularly preferably from 10,000 to 30,000.

  When the fluoropolymer is molded by casting or the like, the weight average molecular weight of the fluoropolymer is preferably from 3,000 to 50,000, more preferably from 5,000 to 50,000, and even more preferably from 10,000 to 30,000. Is particularly preferred. If the mass average molecular weight of the fluorinated polymer is at least the lower limit of this range, the cured product tends to have excellent mechanical strength and heat resistance. Tend to be secured. In particular, when sealing an SMD type LED (LED module with a cup-shaped reflector), fluidity is important. If the mass average molecular weight is too large, the melting temperature at the time of molding the SMD type LED increases, and the curing reaction rate increases, so that the melt fluidity decreases over time and defoaming becomes difficult. When the mass average molecular weight of the fluoropolymer is in this range, the fluoropolymer is suitable for sealing SMD type LEDs.

  When the fluorinated polymer is used as a molded article such as a sheet, the weight average molecular weight of the fluorinated polymer is preferably from 10,000 to 100,000, particularly preferably from 20,000 to 50,000. For example, when sealing a COB type LED (an LED which has no reflector and a plurality of elements are collectively sealed with a sealing resin), heat sealing may be performed using a sheet-shaped sealing resin. is there. In this case, the sheet-like fluoropolymer is superimposed on the substrate on which the LED element is mounted, and heated and flown at 100 to 150 ° C. to cover the LED element with the fluoropolymer, and the LED element is sealed by crosslinking. it can. In this case, in order to seal without leaving any gaps or bubbles, it is preferable to cover the fluoropolymer sheet while applying pressure. When the mass average molecular weight of the fluorinated polymer is in this range, the fluorinated polymer is suitable for sealing the above-mentioned COB type LED.

  The mass average molecular weight can be determined by gel permeation chromatography (GPC) as a molecular weight in terms of PMMA (polymethyl methacrylate).

[Production method of fluoropolymer]
The fluoropolymer includes a unit represented by the following formula (1a) and a fluorinated polymer containing the unit (2), and a hydrazine compound represented by the following formula (5) (hereinafter, also referred to as “hydrazine compound”). )).

ＨＲ^１Ｎ−ＮＲ^２Ｈ （５）

HR ¹ N-NR ² H (5)

In the formula (1a), R ³ is an alkyl group, R ^f1 is as defined in the formula (1), and the examples and preferred ranges are also the same. In the formula (5), R ¹ and R ² are as defined in the formula (1), and the examples and preferred ranges are also the same.

Completion of the reaction for converting the fluorine-containing polymer having the unit (1a) into the unit (1) by reaction with the hydrazine compound can be confirmed by disappearance of the infrared (IR) absorption of the -COOR ³ group.

(Fluorine-containing polymer containing unit (1a))
The fluorine-containing polymer containing the unit (1a) of the present embodiment is obtained by polymerizing the monomer forming the above-mentioned unit by a known method (for example, a method described in WO 2015/098773). .

(Hydrazine compound)
Examples of the hydrazine compound include hydrazine, hydrazine monohydrate, methylhydrazine, and 1,2-dimethylhydrazine. As the hydrazine compound, hydrazine monohydrate is preferable from the viewpoints of safety and better heat curability of the obtained fluoropolymer. The form of the hydrazine compound used for the reaction may be an aqueous solution or a salt. As the hydrazine compound, a commercially available product can be used.

(Reaction conditions)
The amount of the hydrazine compound to be used is preferably 1 to 20 mol, more preferably 1.2 to 10 mol, per 1 mol of the group represented by -COOR ³ of the fluoropolymer containing the unit (1a). 0.5-5 mol is particularly preferred.

  The reaction between the fluorinated polymer having the unit (1a) and the hydrazine compound can be performed in the presence of a solvent. As the solvent, those that dissolve the raw material components (fluorinated polymer containing unit (1a) and unit (2), hydrazine compound) are preferable. A fluorinated solvent that dissolves a fluorinated polymer containing at least the unit (1a) and the unit (2) is more preferable. Further, an alcohol may be added to the fluorinated solvent to disperse the hydrazine compound.

  The fluorinated solvent contains fluorine and carbon, and may contain chlorine, oxygen and hydrogen. Examples of the fluorinated solvent include fluorinated alkanes, fluorinated aromatic compounds, fluoroalkyl ethers, fluorinated alkylamines, and fluoroalcohols.

The fluorinated alkane preferably has 4 to 8 carbon atoms. Commercially available fluorinated alkanes include, for example, CF ₃ CH ₂ CF ₂ H (HFC-245fa), CF ₃ CH ₂ CF ₂ CH ₃ (HFC-365mfc), perfluorohexane, 1H-perfluorohexane, perfluorooctane, C ₆ F ₁₃ H (manufactured by Asahi Glass Company, ASAHIKLIN _{(TM) AC-2000), C 6} F 13 C 2 H 5 ( manufactured by Asahi Glass Company, ASAHIKLIN _{(TM) AC-6000), C 2} F 5 CHFCHFCF 3 ( Vertrel (registered trademark) XF, manufactured by Kemers Corporation.

  Examples of the fluorinated aromatic compound include hexafluorobenzene, trifluoromethylbenzene, perfluorotoluene, and bis (trifluoromethyl) benzene.

The fluoroalkyl ether preferably has 4 to 12 carbon atoms. Commercially available fluoroalkyl ethers include, for example, CF ₃ CH ₂ OCF ₂ CF ₂ H (Asahiclean (registered trademark) AE-3000, manufactured by Asahi Glass Co., Ltd.) and C ₄ F ₉ OCH ₃ (manufactured by 3M, Novec (registered trademark) 7100), C ₄ F ₉ OC ₂ H ₅ (manufactured by 3M, Novec (registered trademark) 7200), C ₂ F ₅ CF (OCH ₃ ) C ₃ F ₇ (manufactured by 3M, Novec (registered trademark) 7300) And the like.

  Examples of the fluorinated alkylamine include perfluorotripropylamine and perfluorotributylamine.

  Examples of the fluoroalcohol include 2,2,3,3-tetrafluoropropanol, 2,2,2-trifluoroethanol, hexafluoroisopropanol and the like.

  Other examples of the fluorinated solvent include dichloropentafluoropropane (HCFC-225) and perfluoro (2-butyltetrahydrofuran). As a commercially available product of dichloropentafluoropropane, AK-225cb (manufactured by Asahi Glass Co., Ltd.) can be mentioned.

  The reaction is preferably performed, for example, by dissolving the fluorinated polymer containing the unit (1a) and the unit (2) in the above fluorinated solvent, and adding the hydrazine compound at 0 to 30 ° C. This is further heated to 30 to 100 ° C. and reacted for 1 minute to 10 hours to obtain a desired fluorinated polymer.

[Curable composition, coating composition]
The cured product of the fluoropolymer of the present embodiment can be produced using only the fluoropolymer. Further, it can be produced from a curable composition containing the above-mentioned fluoropolymer (but not containing a solvent) or a coating composition containing the above-mentioned curable composition and a solvent.

  Components other than the fluoropolymer in the curable composition include inorganic particles, silane coupling agents, fluoropolyether compounds, and the like, and these components are in a range that does not significantly affect the transparency of the cured product. Can be added. Here, the silane coupling agent and the fluoropolyether compound include, for example, those described in International Publication No. 2015/098773.

  As the inorganic particles, metal oxides such as silica, titania, zirconia, and alumina, and various phosphor particles are preferable. The diameter of the inorganic particles is preferably 1 nm to 10 μm, and particularly preferably 1 nm to 1 μm from the viewpoint of suppressing light scattering and ensuring the transparency of the composition. The content of the inorganic particles is preferably from 20 to 200 parts by mass, particularly preferably from 50 to 100 parts by mass, per 100 parts by mass of the fluoropolymer, from the viewpoint of increasing the refractive index of the cured product. If the content of the inorganic particles is at least the lower limit of the above range, the cured product will have a higher refractive index, and if it is at most the upper limit of the above range, the moldability will be excellent.

  Examples of the solvent in the coating composition include the above-mentioned fluorine-containing solvents. The coating composition may contain an alcohol to the extent that the fluoropolymer does not precipitate.

  The content of the solid content in the coating composition is preferably from 1 to 99% by mass. The content of the fluoropolymer in the coating composition is preferably from 1 to 99% by mass.

[Method for producing cured product formed from fluoropolymer]
The cured product formed from the fluoropolymer having a hydrazide group in the present embodiment is produced by heating the fluoropolymer or irradiating the fluoropolymer with active energy rays. Heating and active energy ray irradiation may be used in combination. In particular, it is preferable to heat and cure the fluoropolymer. When the fluorine-containing polymer is cured by heating, the heating temperature is preferably from 150 to 300 ° C, more preferably from 200 to 250 ° C. The heating time depends on the temperature, but is preferably 1 minute to 10 hours, more preferably 1 to 5 hours, and even more preferably 2 to 4 hours.

[Method of manufacturing molded article]
The molded article can be produced using a curable composition containing a fluoropolymer or a coating composition containing a curable composition and a solvent. As a method for producing a molded article, a method in which the curable composition is caused to flow by heating, and poured into a mold to have a predetermined shape, and the curable composition is cast on the surface of the mold, and a sheet-like or film-like molded article is formed. And a method of forming the curable composition into a predetermined shape by extrusion molding, transfer molding, or the like, and a method of cutting or bending a formed sheet or film into a predetermined shape, and the like.
It is preferable to use a coating composition when producing a thin-film molded article or a thin-film molded article integrated with a substrate.

  Examples of the coating method of the coating composition include a spin coating method, a wipe coating method, a spray coating method, a squeegee coating method, a dip coating method, a die coating method, an ink jet method, a flow coating method, a roll coating method, a casting method, a Langmuir-Blodgett method. And a gravure coating method.

[Cured product of fluoropolymer]
The cured product of the fluoropolymer has no foaming, has high transmittance of visible light of 400 nm or more, and has no light deterioration, and thus is useful as a sealing material or a lens of a high-output LED. Further, since it has a molecular structure having essentially no absorption at a wavelength of 300 to 400 nm, it is also useful as a light-transmitting sealing material or a lens of an ultraviolet LED having an emission wavelength of 365, 380, or 405 nm.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description. Example 1 is an Example and Examples 2 and 3 are Comparative Examples. The evaluation of each case was performed according to the method described below.

[Evaluation method]
<Mass average molecular weight>
The mass average molecular weight of the fluoropolymers P1, Q1, and R1 was determined by gel permeation chromatography (GPC) using PMMA (polymethyl) using CF ₂ ClCF ₂ CHClF (trade name: AK-225cb, manufactured by Asahi Glass Co., Ltd.) as a solvent. It was calculated as a molecular weight in terms of (methacrylate).

<-COOCH ₃ group content in fluoropolymer>
The -COOCH ₃ group content in the fluoropolymer was determined from ¹⁹ F-NMR.

<Elastic modulus>
Using the film manufactured in each example, the measurement was performed in a viscoelasticity analysis mode of TMA / EXSTAR SS7100 manufactured by Hitachi High-Tech. Measurement temperature range: −40 ° C. to 200 ° C., heating rate: 5 ° C./min, frequency: 0.05 Hz.

<UV-LED lighting test>
Using a constant current power supply (manufactured by Sanhayato), a current of 300 mA was supplied at room temperature without installing a heat sink, and the output of the LED was measured using a small integrating sphere-fiber multichannel spectrometer USB2000 (manufactured by Ocean Optics). .

[unit]
The units mentioned in the following production examples are as follows.

[Production Example 1: Production of fluoropolymer P2 having (a2) unit and (b1) unit]
After degassing a 1 L stainless steel autoclave with a stirrer in vacuum, 11.2 g of perbutyl PV (50 mass% AK-225cb solution: made by NOF CORPORATION) as a polymerization initiator, CF ₂ = CFOCF ₂ CF ₂ CF ₂ COOCH ₃ of _{18.7g, CF 2 = CFOCF 2 CF} 2 CF 3 OCF = of _{CF 2 4.2g, CF 2 = CFOCF} 2 CF 2 CF 3 ( hereinafter, referred to as "PPVE".) of 412. 7 g and 517.2 g of AC-2000 were charged. After press-fitting 48.7 g of TFE while stirring, the internal temperature was raised to 60 ° C. to initiate polymerization. While maintaining the pressure in the autoclave at 0.47 MPa, polymerization was carried out for 3 hours while adding TFE to the autoclave. The total charge of TFE was 104.9 g.

  After cooling the inside of the autoclave, the content was transferred to a 5 L glass beaker, and 2200 g of AE-3000 was added with stirring, whereby a fluoropolymer was precipitated. After removing the supernatant liquid, drying was performed to obtain 125.0 g of the fluoropolymer P1. The fluoropolymer P1 was soluble in AK-225cb and AC-2000, and was insoluble in methanol, acetone and tetrahydrofuran (hereinafter also referred to as “THF”). The unit composition of the fluoropolymer P1 is unit (a1): unit (c1): unit (d1) = 1.3: 68.8: 29.9 (molar ratio), and the mass average molecular weight is 32,700. there were. The molar ratio of the unit (b1) is estimated to be 0.3 from the charging ratio with the unit (a1).

After dissolving 4 g of the fluoropolymer P1 in 22.8 g of AC-2000, 0.17 g of a solution obtained by diluting hydrazine monohydrate (purity 79%, manufactured by Tokyo Chemical Industry Co., Ltd.) five-fold with methanol was added. Added and stirred vigorously. Then, after stirring at 40 ° C. for 2 hours, 0.2 g of methanol was added, and the mixture was further heated at 40 ° C. for 5 hours. A part of the reaction solution was cast on a glass plate, and the solvent was volatilized by heating at 60 ° C. to produce a film having a thickness of 50 μm. When infrared absorption (IR) was measured, the absorption at 1,794 cm ⁻¹ based on C ＝ O of —COOCH ₃ group in the unit (a1) disappeared, and 1,718 cm based on C ＝ O of —CONHNH ₂ group. ^Since the absorption of ^-1 was newly generated, it was confirmed that the unit (a1) was converted into the unit (a2). When methanol was added to the reaction solution, a precipitate was formed. The precipitate was vacuum-dried at 60 ° C. to obtain 3.8 g of a fluoropolymer P2. Since the —COOCH ₃ group and the —CONHNH ₂ group have the same molecular weight, the mass average molecular weight of the fluorinated polymer P2 is the same as that of the fluorinated polymer P1 and the same as that of the fluorinated polymer P1.

[Example 1: Cured product of fluoropolymer P2]
0.7 g of the fluoropolymer P2 was placed on a 5 cm square glass plate, and heated and deaerated at 150 ° C. in a vacuum oven. After returning to normal pressure, a spacer frame having a thickness of 0.5 mm is placed around P2, a release film made of a fluororesin and a glass plate are sequentially placed thereon, and a 150 g weight is further placed thereon. Let stand for a minute. Thereafter, the film was taken out of the oven and naturally cooled to obtain an elliptical film having a thickness of 0.5 mm. After releasing the release film from the elliptical film together with the glass plate placed thereon, the release film was heated to 200 ° C. and heated in an N ₂ atmosphere for 30 minutes. The temperature was further raised to 250 ° C., and the mixture was heated for 2 hours. After cooling, the elliptical film was peeled off from the glass plate on which it was placed to obtain a colorless, transparent, elliptical cured film. The measured light transmittance was 90% at a wavelength of 400 nm and 87% at a wavelength of 365 nm.

  When the viscoelasticity of the cured film was measured, a decrease in the elastic modulus corresponding to the glass transition temperature (Tg) was observed around 5 ° C., and at a temperature higher than Tg, the rubber-like flat portion became almost constant at least up to 200 ° C. Appeared, it was confirmed that the crosslinking reaction occurred by heating at 250 ° C.

A small piece of the uncured fluoropolymer P2 film is placed on a cup-shaped aluminum package on which a 1 W type UV-LED (emission wavelength: 365 nm) manufactured by Nitride Semiconductor Inc. is wire-bonded and heated and melted at 170 ° C. in a vacuum oven. Then, it was made to flow under its own weight while being degassed, and the concave portion of the package was molded. After being taken out of the vacuum oven, the UV-LED was sealed by heating at 200 ° C. for 30 minutes in an N ₂ atmosphere, and further heating and curing at 250 ° C. for 2 hours. When the UV-LED package was soldered to an aluminum wiring board and lit continuously at 300 mA, the output at the start of 365 nm UV was similar to that of the unsealed package, but the output increased by 15% in about 50 hours. Then, the output level was maintained for 1000 hours.

[Production Example 2: Production of fluoropolymer Q2]
0.1 g of V601 (manufactured by Wako Pure Chemical Industries, Ltd.) was charged as a polymerization initiator into a stainless steel autoclave with a stirrer having an inner volume of 200 mL, and after degassing under reduced pressure, CF ₂ = CFOCF ₂ CF ₂ CF ₂ COOCH ₃ was added. 20 g, 40 g of PPVE, and 103 g of AC-2000 were charged. While stirring the contents of the autoclave, 12 g of TFE was injected, and the internal temperature was raised to 80 ° C. to initiate polymerization. Polymerization was carried out for 6 hours while adding TFE while maintaining the pressure in the autoclave at 0.72 MPa. The total charge of TFE was 28.3 g.

  After cooling the inside of the autoclave, the content was transferred to a 500 mL glass beaker, and 200 g of methanol was added with stirring to precipitate a fluoropolymer. After removing the supernatant liquid, drying was performed to obtain 20.6 g of the fluoropolymer Q1. The fluoropolymer Q1 was soluble in AK-225cb and AC-2000, and was insoluble in methanol, acetone and THF. The composition of the fluoropolymer Q1 was such that the unit (a1): the unit (c1): the unit (d1) = 8.0: 75.7: 16.3 (molar ratio), and the mass average molecular weight was 21,700. there were. The fluorinated polymer Q1 and hydrazine monohydrate were reacted in the same manner as in Production Example 1 for a total reaction time of 3 hours, and the unit (a2) was reduced to a half of the unit (a1) of the fluorinated polymer Q1. ) Was obtained to obtain a fluoropolymer Q2. The mass average molecular weight of the fluorinated polymer Q2 is the same as that of the fluorinated polymer Q1.

[Example 2: Cured product of fluoropolymer Q2]
0.7 g of the fluoropolymer Q2 was placed on a 5 cm square glass plate, and heated and deaerated at 130 ° C. in a vacuum oven. After returning to normal pressure, a spacer frame having a thickness of 0.5 mm is placed around the fluoropolymer Q2, a release film made of fluororesin and a glass plate are sequentially placed thereon, and a weight of 150 g is further placed thereon. Was placed on the plate and allowed to stand for 10 minutes. Thereafter, the film was taken out of the oven and naturally cooled to obtain an elliptical film having a thickness of 0.5 mm. After the release film placed on the fluoropolymer was peeled off together with the glass plate placed thereon, the film was heated to 200 ° C. in an N ₂ atmosphere and foamed violently. Again, the fluoropolymer Q2 was heated and degassed at 130 ° C in the same manner as above, and allowed to stand to form an uncured elliptic film. The obtained uncured elliptic film was heated at 150 ° C for 1 hour. Then, the temperature was further increased to 250 ° C., and the mixture was heated for 2 hours. After cooling, the elliptical film was peeled off from the glass plate on which it was placed to obtain a transparent cured film having wrinkles and haze on the surface.

  In addition, sealing was attempted using the same UV-LED as in Example 1 using the fluoropolymer Q2, but when molding by heating and melting at 150 ° C., foaming could not be performed under reduced pressure, and bubbles remained. Since the resin was cured as it was, the output of 365 nm UV was reduced to about half.

[Production Example 3: Production of fluoropolymer R2]
After vacuum degassing of a stainless steel autoclave with an internal volume of 1 L with a stirrer, 4.5 g of perbutyl PV as a polymerization initiator, 25.0 g of CF ₂ = CFOCF ₂ CF ₂ CF ₂ COOCH ₃ , and 407.9 g of PPVE And 514.2 g of AC-2000 were charged. After press-fitting 48.4 g of TFE while stirring, the internal temperature was raised to 60 ° C. to initiate polymerization. Polymerization was carried out for 4 hours while adding TFE while maintaining the pressure in the autoclave at 0.49 MPa. The total charge of TFE was 97.2 g.

  After cooling the autoclave, the content was transferred to a 5 L glass beaker, and 2200 g of AE-3000 was added with stirring to precipitate a fluoropolymer. After removing the supernatant liquid, drying was performed to obtain 107.1 g of a fluoropolymer R1. The fluoropolymer R1 was soluble in AK-225cb and AC-2000, and was insoluble in methanol, acetone and THF. The unit composition of the fluoropolymer R1 is unit (a1): unit (c1): unit (d1) = 1.7: 67.6: 30.7 (molar ratio), and the mass average molecular weight is 39,400. there were.

After dissolving 4 g of the fluoropolymer R1 in 22.8 g of AC-2000, 0.27 g of a solution obtained by diluting hydrazine monohydrate (purity 79%, manufactured by Tokyo Chemical Industry Co., Ltd.) five-fold with methanol was added. Added and stirred vigorously. After stirring at 40 ° C. for 2 hours, 0.3 g of methanol was added, and the mixture was further heated at 40 ° C. for 6 hours. A part of the reaction solution was cast on a glass plate and heated at 60 ° C. to evaporate the solvent to produce a film having a thickness of 50 μm, and its infrared absorption (IR) was measured. As a result, the unit (a1) in the absorption of 1,794Cm ^-1 based on C = O of -COOCH ₃ groups and the disappearance of, the new absorption 1,718Cm ^-1 based on C = O of ₂ groups -CONHNH From the generation, it was confirmed that the unit (a1) was converted to the unit (a2). When methanol was added to the remaining reaction solution, a polymer precipitated. The precipitated polymer was dried in a vacuum at 60 ° C. to obtain 3.8 g of a fluoropolymer R2.

[Example 3: Cured product of fluoropolymer R2]
0.7 g of the fluoropolymer R2 was placed on a 5 cm square glass plate, and heated and deaerated at 150 ° C. in a vacuum oven. After returning the inside of the vacuum oven to normal pressure, a spacer frame having a thickness of 0.5 mm is set around the fluorinated polymerization R2, and a fluororesin release film and a glass plate are sequentially placed thereon, and further from there. A weight of 150 g was placed and allowed to stand for 10 minutes. Thereafter, the fluoropolymer R2 was taken out of the oven and naturally cooled to obtain a 0.5 mm-thick elliptical film as a cured product of the fluoropolymer R2. After releasing the release film from the oval film together with the glass plate placed thereon, the release film was heated to 200 ° C. in an N ₂ atmosphere, kept for 30 minutes, further heated to 250 ° C., and heated for 3 hours. . After cooling, the elliptical film was peeled off from the glass plate on which it was placed to obtain a colorless, transparent, elliptical cured film. When the light transmittance was measured, it was 88% at a wavelength of 400 nm and 80% at 365 nm, and the UV transmittance was slightly lower than that of the cured product of Example 1.

  Further, when the viscoelasticity of the obtained cured film was measured, a decrease in the elastic modulus corresponding to the glass transition temperature (Tg) was observed around 5 ° C., and at a temperature higher than Tg, a rubbery flat portion appeared. Since the elastic modulus was slightly lower than that of the cured product of Example 1, it was found that the crosslink density was slightly lower.

The UV-LED was sealed by heating at 200 ° C. for 30 minutes in an N ₂ atmosphere and further heating and curing at 250 ° C. for 2 hours in the same manner as in Example 1 using the fluoropolymer R2. When energization was performed at 300 mA, the output of 365 nm UV was 10% lower than that of the unsealed one. When continuous energization was performed for 300 hours, foaming occurred, and the output was reduced by half.

Regarding the fluoropolymers of Production Examples 1 to 3 and the cured products of Examples 1 to 3, the content of -CONHNH ₂ group, the light transmittance of the cured film, the curing temperature, the presence or absence of foaming during LED sealing, and the UV-LED Table 1 shows the results of the lighting test.

  From the results of Example 1, since the fluoropolymer of the present embodiment contains, in addition to the unit (1) which is a crosslinking group, the unit (2) as a branched structure contributing to the formation of the crosslinking group, it has a melt flowability It can be seen that LED sealing without foaming is possible without impairing the moldability, and the melt moldability is excellent. Furthermore, the cured product obtained from the fluorinated polymer of this embodiment has excellent heat and light resistance as a result of a continuous lighting test for 1000 hours. On the other hand, in Example 2 in which the content ratio of the unit (1) is high and the unit (2) is not contained, the composition is cured at a lower temperature than that of Example 1, but when heated and fluidized and molded into an LED, the curing proceeds. It was difficult to suppress foaming. In addition, the fluoropolymer of Example 3 which did not contain the unit (2) at the same content of the unit (1) as in Example 1 could be molded without foaming, but foamed during continuous lighting. This indicates that heat resistance is poor due to insufficient crosslinking.

According to the present invention, it is possible to provide a fluorine-containing polymer which is heat-curable and has both melt moldability and heat resistance and UV resistance.
The fluoropolymer of this embodiment is useful as an optical material, an encapsulating material for an element, an inorganic EL phosphor dispersing material, a material for an optical waveguide, a heat and chemical resistant sealing material, an adhesive, and a coating material.
The coating composition of the present embodiment is useful as a release agent, a material for an antifouling coat, a material for a chemical-resistant protective coat, and the like. Since the fluoropolymer of the present invention can be cured by UV, it can be coated on a substrate having low heat resistance such as a plastic material.
The cured product of the fluoropolymer of the present embodiment is useful as a light-transmitting sealing material for UV-LED. It is also used as an underfill material for flip chip type devices.
The molded article made of the cured product of the fluoropolymer of the present embodiment is useful as a core material and a clad material of an optical fiber, a core material and a clad material of an optical waveguide, and a lens material.
The substrate provided with the cured product of the fluoropolymer of the present embodiment is useful as a light-emitting element, a semiconductor element, a solar cell element, a short-wavelength light-emitting element, and the like. It is useful as a light emitting device having an object.

Claims (11)

A fluoropolymer containing a unit represented by the following formula (1) and a unit represented by the following formula (2).

(In the formula (1), R ^f1 is a fluoroalkylene group or a fluoroalkylene group having 2 or more carbon atoms having an etheric oxygen atom between carbon and carbon atoms, and R ¹ and R ² are each independently: It is a hydrogen atom or an alkyl group.)

(In formula (2), X ¹ , X ² , and X ³ are each independently a fluorine atom or a hydrogen atom, two Q ² are each independently a single bond or an etheric oxygen atom, and R ^f2 is a carbon atom. A fluoroalkylene group having 1 to 6 carbon atoms or a fluoroalkylene group having 2 to 25 carbon atoms having an etheric oxygen atom between carbon-carbon atoms.) At least a portion of the unit represented by the formula (1) _{is, - [CF 2 -CF (O} (CF 2) 3 CONHNH 2)] - a is a fluorine-containing polymer according to claim 1.   The fluorinated polymer according to claim 1, further comprising a unit derived from fluoroethylene. The fluorinated polymer according to any one of claims 1 to 3, further comprising a unit represented by the following formula (3) (excluding units derived from fluoroethylene).
-[CX ⁴ X ⁵ -CY ¹ Y ² ] -... (3)
(In the formula (3), X ⁴ and X ⁵ are each independently a hydrogen atom, a fluorine atom or a chlorine atom;
Y ¹ is a hydrogen atom, a fluorine atom or a chlorine atom;
Y ² represents a hydrogen atom, a fluoroalkyl group, a fluoroalkyl group having 2 or more carbon atoms having an etheric oxygen atom between carbon-carbon atoms, a fluoroalkoxy group, or a carbon atom having an etheric oxygen atom between carbon-carbon atoms. It is a fluoroalkoxy group of two or more. )   The ratio of the unit represented by the formula (1) is 0.1 to 20 mol%, and the proportion of the unit represented by the formula (2) is 0 to the total of the units contained in the fluoropolymer. The fluorine-containing polymer according to any one of claims 1 to 4, wherein the content is 0.05 to 3 mol%.   The proportion of the unit represented by the formula (1) is 0.1 to 5 mol%, and the proportion of the unit represented by the formula (2) is 0 to the total of the units contained in the fluoropolymer. The fluorine-containing polymer according to any one of claims 1 to 4, wherein the content is 0.05 to 3 mol%.   The fluorinated polymer according to any one of claims 1 to 6, wherein the weight average molecular weight is 3,000 to 100,000.   The fluorine-containing polymer according to any one of claims 1 to 6, having a weight average molecular weight of 5,000 to 100,000.   A method for producing a cured product of a fluoropolymer, comprising heating the fluoropolymer according to any one of claims 1 to 8 at 150 to 300 ° C.   A light-emitting device comprising: a light-emitting element; and a cured product of the fluoropolymer according to claim 1.   The light emitting device according to claim 10, wherein the light emitting element is a white LED or an ultraviolet LED.