JPH032408A - Mirror - Google Patents

Abstract

PURPOSE:To promote water repellency, antifouling efficiency and ultraviolet radiation resistance with a low refractive index by coating the surface of a mirror with a polymer having a fluorine-containing alicyclic construction in a main chain obtained by cyclopolymerization. CONSTITUTION:The surface of a mirror is coated with a polymer having fluorine-containing alicyclic construction in a main chain obtained by cyclopolymerization. According to the constitutiion, a surface layer having excellent water repellency, antifoulig efficiency, weather resistance, laser beam resistance, etc. with a low refractive index can be formed and, in particular, a polymer having a high fluorine content can possess thermal, chemical and moisture resistances as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mirror having a surface layer made of a polymer having a fluorine-containing aliphatic ring structure.

[Prior Art] When it rains, water droplets adhere to the surfaces of mirrors such as door mirrors and fender mirrors of automobiles, which may impede safe visibility.

Furthermore, when the surface of a curved mirror or the like is coated with a resin, there is a problem in that the resin deteriorates due to ultraviolet rays, causing yellowing, cracking, etc., and the mirror no longer functions as intended.

Further, a surface mirror using a silver metal surface is sometimes used as a laser beam reflecting mirror, but in this case, there is a problem that the silver surface is attacked by oxygen in the air.

[Problem M to be solved by the invention] The present invention solves the drawbacks observed in mirrors made of conventional materials as described above, and provides a new mirror with excellent water repellency, stain resistance, and ultraviolet resistance. The purpose is to

[Means for Solving the Problems] Based on the recognition of the above-mentioned problems, the present inventors have made extensive studies and found that a polymer having a fluorine-containing aliphatic ring structure has high transparency and a low refractive index, It has been newly discovered that this material is extremely advantageous as a material that provides a stable mirror surface layer.

The present invention was thus completed based on the above findings, and provides a novel mirror whose surface is coated with a polymer having a fluorine-containing aliphatic ring structure.

In the present invention, the polymer having a fluorine-containing aliphatic ring structure may be exemplified over a wide range of examples, including those that are conventionally known or well-known. Therefore, in the present invention, a fluorine-containing polymer having the above-mentioned specific ring structure in the main chain is preferably employed.

For example, those having a ring structure like that of a ship's warehouse. Among these, polymers having the following ring structures are typical.

However, the content of the present invention is not limited to these only.

General Formula General Formula There are two methods for producing these polymers as follows. However, it is not limited to these manufacturing methods.

1. By cyclization polymerization (1) CF2: CF-0-CF; aCF2-0-CF
zCF2↓ Radical polymerization (2) CF2”CF-CF2-CFCI-CFz-C
F": CF3I Radical Polymerization (USP 3978030) In the above, a polymer having a perfluoroaliphatic ring structure was exemplified, but in the present invention, some of the fluorine atoms in the above example are replaced by other hydrogen atoms or organic groups. or obtained by metathesis polymerization (USP 3202643 etc.) (3) CF2=CF-0-CFa-CF=CF2 Meng
Also included are those having a ring structure such as those formed by radical polymerization.

Therefore, the polymer having a specific ring structure in the present invention can be obtained more smoothly and advantageously by the above-mentioned cyclopolymerization, but in particular, the polymer has two polymerizable groups with different polymerizability in the molecule, and In these two cases, the number of atoms in the linear part of the connecting chain connecting the polymerizable groups is 2, which uses a cyclic monomer.
By using ~7 monomers, the cyclization polymerization can proceed smoothly and advantageously by suppressing gelation by-products without employing ultra-high pressure conditions or large dilution conditions.

As a monomer suitable for the above-mentioned cyclization polymerization, first of all, it is desirable that the monomer has two carbon-carbon multiple bonds having different polymerizability. Usually a carbon-carbon double bond is employed. For example, a fluorine-containing monomer with two non-symmetrical multiple bonds, a vinyl group and an aminol group, a vinyl ether group and a vinyl group, a fluorine-containing multiple bond and a hydrocarbon multiple bond, a perfluorinated multiple bond and a partially fluorinated multiple bond. Examples include: Second, the number of atoms in the straight part of the linking chain connecting these two carbon-carbon multiple bonds is 2 to 7.
It is desirable that The number of atoms in the straight part of the connected chain is 0
When the number is 1 to 1, cyclization polymerization is difficult to occur, and the same holds true when the number is 8 or more. Generally preferred is a case where the number of atoms is 2 to 5.

In addition, the connecting chain is not limited to a straight line, and may have a side chain structure or a ring structure, and the constituent atoms are not limited to carbon atoms, but may also include heteroatoms such as O, S, and H. . Thirdly, it is desirable that the fluorine content be 10% by weight or more. If the fluorine content is too low, the specificity of fluorine atoms will be difficult to exhibit. Naturally, perfluoromonomers are preferably employed.

Specific examples of the above-mentioned specific fluorine-containing monomer include CF2
=CFOCF2CF”CF2. CF2;CFOCF2
CF2CF=CFpCF2"CFOCF2CF=CH2
,CF2”CFOCF2CF2CH”CH2゜CF2=
CFOCF2(Cab)yNHCC)(=CH2(
However, X is an integer of 0 to 3) Fa CF3 CH2"CHOCH2CH2CF2CF"CF2, etc. may be exemplified.

In the present invention, those having one vinyl ether group such as CF2''CFO- are preferably employed in terms of polymerization reactivity, cyclization polymerization, gelation suppression, etc. In particular, perfluoroallyl vinyl ether (CF2=CFOCF2CF
=CF2) and perfluorobutenyl vinyl ether (CF2=CFOCF2CF2CF=CF2).

The above-mentioned monomer components can be used alone or in combination of two or more, and there is no problem even if they are copolymerized in combination with other copolymer components to the extent that the essence of these components is not impaired. If necessary, the polymer may be crosslinked by some method.

Other monomers to be copolymerized are not particularly limited as long as they have radical polymerizability, and include fluorine-containing monomers,
A wide range of hydrocarbons and others may be exemplified. Of course, these other monomers may be used alone in radical copolymerization with the monomer capable of introducing the specific ring structure, or two or more of these other monomers may be used in combination to carry out the above copolymerization reaction. You can let them do it. In the present invention, it is usually desirable to select fluorine-containing monomers such as fluoroolefins and fluorovinylethers as other monomers. For example, preferred examples include tetrafluoroethylene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, or perfluorovinyl ether containing a functional group such as a carboxylic acid group or a sulfonic acid group. ,
Also exemplified are chlorotrifluoroethylene and the like.

As for the copolymer composition, in order to take advantage of the characteristics of the specific fluorine-containing aliphatic ring structure aimed at in the present invention, the composition of the cyclic structure is preferably 20% or more, and more preferably 4% or more.
It is desirable that it is 0% or more.

In the present invention, as a method for crosslinking the fluoropolymer, commonly used methods can be appropriately used. For example, crosslinking can be achieved by copolymerizing a monomer having a crosslinking site, by adding a crosslinking agent, or by using radiation or the like.

Furthermore, various additives such as antioxidants and ultraviolet stabilizers can be added to the fluorine-containing polymer in the present invention in order to improve practicality.

Since the polymer having a specific ring structure in the present invention is soluble in fluorine-based solvents, it is also possible to create a polymer layer on the surface of the mirror by cast molding from a solution. Furthermore, as a thermoplastic resin, it has a low melting temperature and a relatively low melt viscosity, so it is also possible to create a film by hot melt molding and then attach it to the surface of a mirror.

The solvent to be used is not limited as long as it dissolves the above polymer, but examples include perfluorobenzene, "Afluid" (trade name: fluorinated solvent manufactured by Asahi Glass Co., Ltd.), "Fluorinert" (trade name: manufactured by 3M Company). Fluorinated liquids), trichlorotrifluoroethane, etc. are suitable.Of course, two or more suitable solvents can be used in combination as a solvent.Particularly in the case of a mixed solvent, hydrocarbons, alcohols, and other solvents are suitable. An organic solvent can also be used in combination.The solution concentration is 0.
01wt% to 50wty, preferably 0.1wt
! ~20wtχ.

[Function] In the present invention, the polymer having a fluorine-containing aliphatic ring structure has low crystallinity or almost no crystallinity, so it exhibits high transparency and high light transmittance despite being a fluororesin. Moreover, since it is a fluorine-containing polymer, it is thought to have a lower refractive index than ordinary hydrocarbon resins, and is also superior in moisture resistance, weather resistance, and chemical resistance. However, it goes without saying that such explanations are provided to assist in understanding the present invention and are not intended to limit the present invention.

[Examples] Next, Examples of the present invention will be described in more detail, but it goes without saying that this description does not limit the present invention.

Synthesis Example 1 35 g of perfluoroallyl vinyl ether, 5 g of trichlorotrifluoroethane (hereinafter abbreviated as R113), 150 g of ion-exchanged water, and 35 mg of (C3F7C00)2 as a polymerization initiator were added to an inner volume of 200 m
It was placed in a pressure-resistant glass autoclave.

After purging the system with nitrogen three times, suspension polymerization was carried out at 26°C for 23 hours. As a result, 28 g of polymer was obtained.

When we measured the infrared absorption spectrum of this polymer, we found that
1660 cm- due to the two-set bond present in the monomer.
+, there was no absorption near 1840 cm-1. Further, when this polymer was dissolved in perfluorobenzene and a 19F NMR spectrum was measured, a spectrum showing the following repeating structure was obtained.

The intrinsic viscosity [η] of this polymer is “Florinat” FC
-75 (Product name: Liquid whose main component is perfluoro(2-butyltetrahydrofuran) manufactured by 3M Company, hereinafter FC-
75) and 0.530 at 30'C.

The glass transition point of the polymer is 696C, and it is a tough, transparent, glass-like polymer at room temperature. The 10% thermal decomposition temperature was 462°C, the refractive index was as low as 1.34, and the light transmittance was as high as 95%.

The obtained polymer film (approximately 200μ thick) was subjected to an accelerated weather resistance test using a Sunshine Weatherometer, and the results showed that it had a total light transmittance of more than 90% even after 5000 hours of exposure, and there was no change in appearance. was not recognized at all.

Synthesis Example 2 1.20 g of 1,2,4,4,5.5-heptafluoro-3-oxa-1,6-hebutadiene and 40 g of R-113 were placed in a nitrogen-substituted Mitsuro flask, and a polymerization initiator was added. After adding 20 mg of (C=F7C00)2 and purging the system with nitrogen, polymerization was carried out at 18°C for 10 hours. As a result, 10 g of polymer was obtained. This polymer is 12-
113, and the intrinsic viscosity [η] at 30'C in meta-xylene hexafluoride was 0.96. It was confirmed by 19F and IH NMR that it was a polymer having a ring structure in the main chain.

Additionally, this polymer is colorless and transparent, and has a refractive index of 1.36.
The light transmittance was as high as 93%.

Synthesis example 3 35 g of perfluorobutenyl rubinyl ether.

5 g of R113, 150 g of ion-exchanged water, and 90 mg of diisopropyl peroxydicarbonate as a polymerization initiator were placed in a pressure-resistant glass autoclave having an internal volume of 200 m1. After replacing the system with nitrogen three times, 40
Suspension polymerization was carried out at °C for 23 hours. As a result, 28 g of polymer was obtained.

When we measured the infrared absorption spectrum of this polymer, we found that
1660cm- due to the double bond present in the monomer
+ There was no absorption near 1840 Cm-. Also,
This polymer contains perfluorobenzene and afluid,
It was soluble in florinate. Furthermore, NMR of 19F
When the spectrum was measured, as in Synthesis Example 1, a spectrum corresponding to a ring structure was obtained.

The intrinsic viscosity [η] of this polymer is 306C in FC-75.
It was 0.50. The glass transition point of the polymer is 110
6C, and is a tough, transparent, glass-like polymer at room temperature. The 10% thermal decomposition temperature was 465''C.

The water absorption rate was 0.01% or less, and the refractive index was 1.34.

Example 1.2.3 A solution prepared by dissolving the polymer obtained in Synthesis Examples 1.2 and 3 in a fluorine-based solvent (FC-75) was used to coat the surface of a glass mirror.

The obtained mirror had high water repellency, and when water was poured on it, the water beaded and almost did not adhere to the surface.

Example 4 The surface of a metal convex mirror (curved mirror) was coated with the same polymer solution as used in Example 1. When a water suspension of carbon was sprayed onto this surface and the adhesion of dirt was evaluated, it was found that the mirror coated with the present invention was easy to remove dirt from. It was also found that because the refractive index of the coating layer was low, there was less reflection on the surface of the coating layer, resulting in less image overlap.

[Effects of the Invention] The present invention uses a polymer having a fluorine-containing aliphatic ring structure as a material to create a surface layer with a low refractive index and excellent water repellency, antifouling properties, weather resistance, laser light resistance, etc. It has the excellent effect of obtaining a mirror having a high fluorine content, and those with a particularly high fluorine content are also recognized to have the effect of having heat resistance, chemical resistance, and moisture resistance.

Claims (1)

[Scope of Claims] 1. A mirror whose surface is coated with a polymer having a fluorine-containing aliphatic ring structure. 2. The mirror according to claim 1, wherein the polymer having a fluorine-containing aliphatic ring structure is a polymer having a ring structure in the main chain obtained by cyclization polymerization.