JPH0251548A - Polymer mixture which can show phenomenon of thermoreversible cloud point - Google Patents

Abstract

PURPOSE:To obtain a polymer mixture which can show a phenomenon of a thermoreversible cloud point and has a low refractive index by mixing a polymer based on fluoroalkyl methacrylate with a vinylidene fluoride copolymer. CONSTITUTION:At least 40wt.% fluoroalkyl methacrylate of formula I or II [wherein X is F or H; Z is X or (trifluoro)methyl; m is 1-5; and n is 1-10], e.g., 2,2,3,3,3-pentafluoropropyl methacrylate, is (co)polymerized with, optionally, another monomer copolymerizable therewith (e.g., methyl methacrylate) to obtain a polymer (A) based on the fluoroalkyl methacrylate. Separately, at least 60mol% vinylidene fluoride is copolymerized with, optionally, a monomer copolymerizable therewith (e.g., tetrafluoroethylene) to obtain a vinylidene fluoride copolymer (B). Component A and component B in an amount to give a component A to component B weight ratio of (1-9):(9-1) are mixed together, for example, by dissolving them in a solvent and removing the solvent from the solution or by melt-mixing them at a temperature higher than the melting point.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a polymer mixture that exhibits a suitable thermoreversible clouding point phenomenon and is used in temperature display materials, temperature-sensitive light shields, optical recording materials, etc. Regarding.

[Conventional technology]

The term "set point phenomenon" refers to the phenomenon in which a normally transparent aqueous solution of a certain compound becomes cloudy due to an increase or decrease in temperature. Materials exhibiting this phenomenon include temperature display materials, temperature-sensitive light shields, and writable and erasable materials. It can be used as a material for optical recording. Examples of materials that exhibit the set point phenomenon include acrylamide,
Methacrylamide and derivatives thereof are known, and techniques applying them are disclosed in JP-A-60-250333 and JP-A-60-208336. These technologies make the above-mentioned materials transparent at low temperatures in the coexistence of water.
The point phenomenon is utilized as a polymer membrane by making it opaque at high temperatures or by crosslinking the polyacrylamide derivative into a membrane to make it insoluble in water. In addition, a polymer mixture of a fluorine-based polymer and a transparent polymer, polymethyl methacrylate, is also known as a material that exhibits a set point phenomenon depending on temperature by utilizing phase separation of the polymer.

[Problem that the invention seeks to solve]

Since polyacrylamide, polymethacrylimide, and their derivatives are water-soluble polymers, the coexistence of water is mainly required to utilize the thermoreversible cloud point phenomenon. In order to expand the uses of these materials, we crosslink them to form polymer membranes.
In the case of insolubilization in water, there are problems such as a long molding time for the polymer film, the fact that only a film-like product can be obtained, and a low zero point of 60° C. or lower due to insufficient heat resistance. On the other hand, a polymer mixture of a fluorine-based polymer and polymethyl methacrylate has a high refractive index, so it is not suitable as an optical fiber sheath material. An object of the present invention is to provide a polymer mixture that exhibits reversible astigmatism and has a low refractive index that can be used as a sheath material for optical fibers.

[Means to solve the problem]

The present invention is a polymer mixture exhibiting a thermoreversible point phenomenon, which is obtained by mixing a polymer mainly composed of fluorinated alkyl methacrylate and a vinylidene fluoride copolymer containing 60 mol% or more of vinylidene fluoride. be.

The present invention utilizes the phase separation phenomenon of a polymer mixture obtained by mixing a polymer mainly composed of fluorinated alkyl methacrylate and a vinylidene fluoride copolymer. As this polymer mixture is heated, it undergoes phase separation, becomes cloudy and no longer transmits light, and cools itself (
It becomes transparent.

The vinylidene fluoride copolymer used in the present invention needs to contain 60 mol% or more of vinylidene fluoride units. If the vinylidene fluoride unit is less than 60 mol %, the compatibility with the fluorinated alkyl methacrylate is insufficient, and uniform mixing is required. Monomers to be copolymerized with vinylidene fluoride include tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene,
-Vinyl monomers such as methyl methacrylate, 1,1.1=vinyl trifluoroacetate, and isobutylene are used.

As the fluorinated alkyl methacrylate, - formula % formula % (1) (where χ is a fluorine atom or a hydrogen atom, Z is a hydrogen atom, a fluorine atom, a trifluoromethyl group or a methyl group, and m is 1 to 5
(n is an integer of 1 to 10) is used. Examples of the fluorinated alkyl methacrylates of formula I or (2) include the following compounds. 2,2
-difluoroethyl methacrylate (2F1.i),
2.2.2-Trifluoroethyl methacrylate (3F
M), 2.2,3.3-tetrafluoropropyl methacrylate (4FM), 2.2.3,3.5-pentafluoropropyl methacrylate (5FM), 2,2,3,
3,4.4-hexafluorobutyl methacrylate) (6
FM), 2.2,3,3,4,4.5.5-octafluoropentylmethafrylate (8FM), 1,1-di(
Examples include trifluoromethyl)-2,2,2-trifluoroether methacrylate (9FM).

The polymer containing fluorinated alkyl methacrylate as a main component may be a homopolymer of the above compound or a polymer containing 4
Examples include copolymers containing 0% by weight or more. Examples of other monomers copolymerizable with fluorinated alkyl methacrylate include methyl methacrylate, ethyl methacrylate,
n-propyl methacrylate, n-butyl methacrylate, tertiary butyl methacrylate-1, lauryl methacrylate, nonyl methacrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,
Examples include novinyl monomers such as styrene. The copolymer can be produced by conventional emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or the like. In order to obtain a highly pure copolymer, it is preferable to use a bulk polymerization method. Examples of the polymerization initiator include common radical polymerization initiators, such as organic peroxides such as di-tert-butyl peroxide and dicumyl renog-oxide, methyl-2,2-azobisisobutyrate, and 2,2-azobisisobutyrate. An azo compound such as butyronitrile and an alkyl mercaptan are used as the chain transfer agent.

The polymer mixture of the present invention can be prepared by dissolving a polymer mainly composed of vinylidene fluoride copolymer and fluorinated alkyl methacrylate in a solvent, and then removing the solvent, or by combining two or more polymers at a temperature above the melting point. It can be produced by melt-mixing at a temperature of, for example, 200°C or higher. As the solvent, ethyl acetate, acetone, methyl ethyl ketone, N, -dimethylformamide, dimethyl sulfoxide, dimethyl acetamide, etc. are used.

The polymer mixture of the present invention can also be produced by dissolving the vinylidene fluoride copolymer in a monomer mixture mainly consisting of alkyl fluoride methacrylate, and then curing the polymerizable mixture with light or heat.

As a thermal polymerization catalyst, a peroxide catalyst is used, and as a photopolymerization catalyst, benzophenone, benzoin alkyl ether, 4'-isopropyl-2-hydroxy-
2-methyl-propiophenone, 1-hydroxycyclohexylphenyl ketone, benzyl methyl ketal, 2
, 2-jethoxyacetophenone, chlorothioxanthone, thioxanthone compounds, benzophenone compounds, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, N-methyljetanolamine, triethylamine, and the like.

The light source used for photopolymerization is 150 to 600 nm.
Carbon arc lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, chemical lamps, xenon lamps, and laser lights that emit light at a wavelength of .

The polymer mixture of the present invention preferably contains a polymer mainly composed of fluorinated alkyl methacrylate and a vinylidene fluoride copolymer in a weight ratio of 1=9 to 9:1.

〔Effect of the invention〕

The thermoreversible set-point phenomenon polymer mixture of the present invention has a fairly low refractive index (nD<1.44), so that PMM
It can be used as a sheath material for optical fibers having A as the core material. Furthermore, by heating this optical fiber, the transmission of light changes, and it can also be used as an optical channel.

Example 1 Copolymer consisting of 80 parts by weight of 2.2.6.5.5-pentafluoropropyl methacrylate, 20 parts by weight of methyl methacrylate and 1 part by weight of methacrylic acid (refractive index 1.
416, MFR (at 230°C x 5, B) 9, 8) 5
0 parts by weight and 80 mol% vinylidene fluoride-20 mol% tetrafluoroethylene copolymer (refractive index 1.407, [
η] 50 parts by weight of MEK (25°C 11,175) was dissolved in 300 parts by weight of acetone, and the acetone was evaporated to dryness to obtain a polymer mixture.

Using a 37t press machine, the polymer mixture was heated to 180°C and molded at a pressure of 10 kyf to obtain a film.

This film was transparent and had a refractive index of 1.412. The astigmatism point of this film was 120°C, and the point at which it returned from white to transparent was 105°C. The drawing shows the change in total light transmittance of this polymer mixture film at a heating rate of 5° C./min. The drawing is a graph showing the relationship between temperature and total light transmittance, where the horizontal axis is temperature and the vertical axis is total light transmittance. Curve A in the figure shows the change in total light transmittance when the temperature of the film is increased, and curve B shows the change in total light transmittance when the temperature of the film is decreased.

Example 2 2, 2, 3 used in Example 1. ．． 3. 70 parts by weight of the 3-pentafluoropropyl methacrylate copolymer and 30 parts by weight of the vinylidene fluoride copolymer used in Example 1 were dissolved in 250 parts by weight of acetone, the acetone was evaporated to dryness, and the mixture was cast using a solvent casting method. A film of the polymer mixture was obtained.

This film was transparent and had a refractive index of 1.413. The zero point of this film is 118°C, and the point at which it returns to transparency from whitening is 93°C and 74°C in two stages.
Met.

Example 3 60 parts by weight of the 2,2,3,3.3-pentafluoropropyl methacrylate copolymer used in Example 1 and 70 parts by weight of the vinylidene fluoride copolymer used in Example 1 were added to 300 parts by weight of acetone. A film of the polymer mixture was obtained by the solvent casting method. This film was transparent and had a refractive index of 1.409. The zero point of this film was 128°C, and the point at which it returned from white to transparent was 107°C.

Example 4 After adding and dissolving 0.75 parts by weight of tertiary dodecyl mercaptan and 0.4 parts by weight of lauroyl peroxide to 100 parts by weight of methyl methacrylate, 2 parts were placed facing each other at an interval of 6 In through a polyvinyl chloride gasket. A thermocouple was set in a cell formed from a sheet of tempered glass, and the monomer solution was poured into the cell and immersed in ao'c warm water to polymerize and harden. 60 minutes after the internal temperature reached a peak due to polymerization exotherm, it was removed from the hot water and heated to 120°.
Heat killed for 2 hours in an air heating furnace Φ.

After cooling, the cell was removed, and the resulting resin plate with a thickness of about 6 mm was pulverized in a clean box. The MI value (230'C1 load 3.8 kg) of the obtained polymer was 16.0,
The refractive index is 1.4920. The specific gravity was 1.190 and the heat distortion temperature was 105°C.

100 parts by weight of this polymer and an aqueous methylamine solution (40 parts by weight)
%) in a 31-volume autoclave and reacted for 6 hours in an oil bath at 230°C with repeated nitrogen substitution to obtain a transparent resinous N-methyl methacrylimide-methyl methacrylate copolymer. It was done. The infrared absorption spectrum showed absorption peculiar to methacrylimide, and the imidization rate was 40%. The MI value of the obtained polymer (2
60°C, load 3.8 kg) is 5.7, and refractive index is 1.
530, specific gravity was 1.20, and heat distortion temperature was 147°C.

This core component polymer was spun using a vent spinning machine at a temperature of 240.
The fiber was taken at a spinning speed of 6 m/min at a temperature of 6 m/min to obtain a fiber containing only the core component. The diameter of this core material was 980 μm.

The polymer mixture solution used in Example 1 was charged into an orifice, passed through the core material through the orifice at a take-up speed of 9 m/min, and then passed through a solvent drying cylinder at 90°C to remove the solvent acetone.

The optical fiber thus created has a length of 69803 m, a sheath of 10 μm, and a diameter of 1.
The optical transmission loss of 90 nm light was 490 dB/km. It was 560 aB/km at 650 nm.

Also, cut 5m of this optical fiber and heat it to 125°C.
When heated to 105°C and then held at 105°C, no light was transmitted.

Example 5 Commercially available polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., Kneepilon) was melted in a pent extrusion mode with a barrel temperature of 270'C in the pent part and a barrel temperature of 240'C in the extrusion part.
It is then extruded through a circular nozzle through a gear pump at 230'C and molded into a core resin with a diameter of 980 μm (-).Next, the polymer mixture solution used in Example 2 is charged into an orifice, and the polymer mixture solution is drawn through the orifice at a drawing speed of 13 ml/min. After passing through a polycarbonate core resin, the mixture was passed through an AO'C solvent drying cylinder to remove acetone as a solvent.

The optical fiber thus obtained is 69,808 m1 with 10 sheaths.
It has a diameter of 1 μm and 1 mm. This light) Eyebar has an optical transmission loss of 950 dB/k for light with a wavelength of 770 nm.
It was m. When 3 m of this optical fiber was cut and heated to 120°C and then held at 100°C, no light was transmitted.

Example 6 20 parts by weight of 2,2.3,3.3-pentafluoropropyl methacrylate used in Example 1 and a copolymer of 902% by weight of hexafluoroacetone and 90.98% by weight of vinylidene fluoride (refractive index 1 .393, [η) = t O
80 parts by weight of 25MEK (25°C) was dissolved in 600 parts by weight of acetone, and the acetone was evaporated to dryness to obtain a polymer mixture. A film was then obtained by heating and pressing. This film was transparent and had a refractive index of 1.400.

The setting point for this film was 160°C, and the point at which it turned from white to transparent was 113°C. Further, the sensitivity of this film was lower than that of the vinylidene fluoride-tetrafluoroethylene copolymer films of Examples 1 to 60.

[Brief explanation of the drawing]

The drawing is a graph showing the relationship between temperature and total light transmittance when the temperature of the polymer mixture film obtained in Example 1 is increased or decreased, and curve A shows the relationship between temperature and total light transmittance when the temperature of the polymer mixture film obtained in Example 1 is increased. Curve B shows the relationship when the film temperature is lowered.

Claims (1)

[Claims] A polymer mixture exhibiting a thermoreversible cloud point phenomenon, which is obtained by mixing a polymer mainly composed of alkyl fluoride methacrylate and a vinylidene fluoride copolymer containing 60 mol% or more of vinylidene fluoride.