JPH02282204A - Plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain the plastic optical fiber which is additionally enhanced in heat resistance while maintaining characteristics, such as good flexibility and freedom from disconnection by using a resin essentially consisting of a polybutadiene resin of a hydrogen addition type modified with acrylic at both terminals as the fiber part of the plastic fiber. CONSTITUTION:The heat resistance of the acrylic optical fiber is improved by using the crosslinked matter formed by crosslinking the polybutadiene resin of the hydrogen addition type modified with acrylic at both terminals by a monomer having one or >=2 pieces of carbon-carbon double bond groups as the fiber component. This corsslinked matter has the high heat resistance and is small in coloration at a high temp. although the degree of the coloration varies with the mol. wt. of the resin prior to hardening. The corsslinked matter is extremely excellent in the flexibility, unlike an unsated. polyester resin or the like. Further, the crosslinked matter is extremely excellent in not only the high-temp. characteristics but the low-temp. characteristics of about -30 deg.C as well. The plastic fiber having the excellent heat resistance, high bendability, high toughness, and excellent weatherability is, therefore, obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a heat-resistant plastic optical fiber having a core-sheath profile.

(Prior Art) Conventionally, fibers for transmitting light include quartz glass fibers and plastic fibers. Optical fibers made of quartz glass have very low loss, so they are currently widely used for long-distance optical and data transmission. However, quartz-based optical fibers have the disadvantage that unless the fiber diameter is small, they are not flexible and are easily broken. On the other hand, although plastic optical fibers have lower transmission efficiency than quartz fibers, they have the advantage of being lightweight. In addition, plastic optical fibers have a large diameter, have good flexibility, and do not break, and because of their large diameter, a high aperture and large diameter can be obtained, making it easy to connect with various receiving and emitting devices, and it is also inexpensive. Due to these characteristics, it is used for short-distance transmission of electronic equipment, etc.

The core of plastic optical fibers currently in practical use is usually made of highly transparent polymethyl methacrylate, but since the glass transition point of polymethyl methacrylate is around 100°C, It cannot withstand continuous use at high temperatures. On the other hand, in recent years, attempts have been made to use this plastic optical fiber in electronic devices and automobile engine compartments. Therefore, various attempts are currently being made to improve the heat resistance of plastic optical fibers. For example, in order to improve the heat resistance of polymethyl methacrylate, methyl methacrylate and N-
Method for making arylmaleimide into a copolymer (Japanese Patent Publication No. 43
-9753), a method using a copolymer of polymethyl methacrylate and styrene or vinyltoluene and maleic anhydride (Japanese Unexamined Patent Publication No. 59-200201),
Method of using polycarbonate as a core (Japanese Unexamined Patent Publication No. 1987-
46204), a protective layer is provided on the outside of the sheath layer (cladding layer) (JP-A-58-93003, JP-A-58-
No. 18608], a method using a polymer of methacrylic acid ester having an ester group having a relatively large molecular weight (Japanese Patent Application Laid-Open No. 58-221808), etc. have been proposed.

(Problems to be Solved by the Invention) However, the heat resistance of these acrylic optical fibers is still insufficient, and further improvement in heat resistance is expected.

An object of the present invention is to provide a novel plastic optical fiber that maintains the characteristics of plastic fibers, such as good flexibility and no breakage, and has further improved heat resistance.

(Means for Solving the Problems) As a result of extensive research to overcome the drawbacks of the conventional acrylic optical fibers described above, the present inventors have developed a cross-linked acrylic-modified hydrogenated polybutadiene resin at both ends as a core component. The inventors have discovered that high heat resistance can be obtained and the objective can be achieved when using this method, and based on this knowledge, the present invention has been completed.

That is, the present invention uses, as a core component, a crosslinked product obtained by crosslinking a double-terminated acrylic-modified hydrogenated polybutadiene resin with a monomer having one or more carbon-carbon double bond groups. The present invention provides a plastic optical fiber with the following characteristics.

The crosslinked product of the double-end acrylic-modified hydrogenated polybutadiene resin used as the core in the present invention has high heat resistance. Although this differs depending on the molecular weight of the resin before curing, the coloring at high temperatures is extremely small. Further, unlike conventional resins (for example, unsaturated polyester resins), the crosslinked resin has excellent flexibility. Further, the crosslinked product of the resin has excellent not only high temperature properties but also low temperature properties of about -30''C.

The double-end acrylic-modified hydrogenated polybutadiene resin used in the present invention is preferably represented by the following formula.

(In the formula, Ac represents a methacryloyl group or an acryloyl group, and L is 2 for bonding the Ac group to polybutadiene.
β and m are 0 or 1. n is preferably 4 or more, more preferably 4-60. ) More specifically, there is no particular restriction on the group in the formula, but it is an alkylene group such as -〇-, methylene or ethylene, a phenylene group, -NHCOO- group; or an appropriate combination thereof, and preferably Ac is For example, by bonding through O. The molecular weight of this double-terminated acrylic-modified hydrogenated polybutadiene resin is preferably 400 to 6,000.

This double-terminated acrylic-modified hydrogenated polybutadiene resin can be copolymerized and crosslinked with various monomers to form a crosslinked product.

Monomers capable of forming copolymerized crosslinked products include compounds having one carbon-carbon double bond (unsaturated group) or two.
There are compounds that have more than one.

First, the compound containing one carbon-carbon double bond is not particularly limited, as long as it is a monofunctional acrylic, methacrylic, styrene, or allyl monomer that provides a highly transparent polymer. Specifically, compounds having one single bond include methyl methacrylate, edyl methacrylate, propyl methacrylate, butyl methacrylate, t-butyl meccrylate, hexyl methacrylate, norbornyl methacrylate, adamantyl methacrylate, and methacrylic acid. Methacrylic esters such as benzyl, phenyl methacrylate, naphthyl methacrylate, acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, poly(2-ethylhexyl) acrylate, octyl acrylate, N-cyclohexylmaleimide, N-methylmaleimide , N-ethylmaleimide, N-
N-substituted maleimide compounds such as n-butylmaleimide and N-t-butylmaleimide, styrene, methylstyrene, 1,3-dimethylstyrene, 24-dimethylstyrene, p-butylstyrene, α-methylstyrene, α-methyl- Examples include aromatic vinyl compounds such as p-methylstyrene and vinylnaphthalene, maleic acid, and maleic anhydride.

The amount of the monomer having one double bond in the compound is 70 wt% of the total, preferably 60 wt% or less. When the monomer content exceeds 70 wt%, heat resistance decreases significantly,
It becomes impossible to use at high temperatures.

Next, there are no particular restrictions on compounds containing two or more double bonds, but polyvalent acrylic compounds, polyvalent allylic compounds,
Examples include polyvalent methacrylic compounds, CR39 (diethylene glycol allyl biscarbonate), and the like.

Specific examples of compounds having two or more carbon-carbon double bonds include diacrylate, triacrylate, dimethacrylate, trimethacrylate, tetramethacrylate, triallylcyanurate, diallylisophthalate,
Such as diallyl fumarate (polyvalent allyl compound, hexamethylene glycol dimethacrylate, neopentyl glycol cyanurate, decamethylene glycol dimethacrylate, trimethylolpropane triacrylate,
p-vinylbenzene, diethylene glycol diacrylate, decamethylene glycol dimethacrylate, trimethylolpropane triacrylate, p-divinylbenzene, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tris(2-hydroxyethyl)in cyanuric acid methacrylate, Polyvalent acrylic compounds such as tris(2-hydroxyethyl)isocyanuric acid acrylate, or diethylene glycol bisallyl carbonate (CR-3
9), but is not limited to this. 1 more
．． 4-butadiol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexadiol dimethacrylate, pentaerythritol tetramethacrylate and polyethylene glycol-200 dimethacrylate , low molecular weight polyvalent acrylic polymers such as polyethylene glycol 200 diacrylate, and the like.

A compound having two or more double bonds has the function of increasing crosslinking points and improving heat resistance. double bond 2
It is desirable that the amount of the compound having more than one compound is 50 wt% or less, preferably 40 wt% or less of the total weight. This compound is 50w
If it exceeds t%, the flexibility of the fiber becomes significantly small.

In the core part of the plastic optical fiber of the present invention, the part made of acrylic-modified hydrogenated polybutadiene resin at both ends maintains high heat resistance, high flexibility, and non-breakability, and the part made of a compound having two or more double bonds It maintains high heat resistance and toughness, and the molecular part that has one double bond has the function of maintaining high flexibility and high transparency.

In the present invention, the compound having a carbon-carbon double bond for crosslinking and curing the acrylic modified hydrogenated polybutadiene resin may have one double bond or two.
It is also possible to use these in combination. When used in combination, the ratio can be determined as appropriate in consideration of desired heat resistance, toughness, flexibility, etc.

Next, the production of the crosslinked product used in the present invention, that is, the crosslinking reaction between the acrylic-terminated hydrogenated polybutadiene resin at both ends and the compound having a carbon-carbon double bond group, can be carried out according to a conventional method.

As the polymerization initiator, common radical reaction initiators such as peroxides such as -benzoyl peroxide, lauroyl peroxide, and dicumenyl peroxide can be used. In order to adjust the molecular weight and reduce scattering within the plastic optical fiber, it is preferable to use a conventional chain transfer agent, such as n-octyl mercaptan, n-dodecyl mercaptan, t-octyl mercaptan, t-hexyl mercaptan, n-hexyl Examples include mercaptans such as mercaptan.

This double-terminated acrylic-modified hydrogenated polybutadiene plastic optical fiber is produced by introducing the resin into a molded body and curing it, rather than using the conventional continuous spinning method, as this resin is a thermosetting resin. It can be done.

When introducing the resin, since the double-end acrylic-modified hydrogenated polybutadiene resin has a very high viscosity at room temperature, it is necessary to heat it to lower the viscosity before introducing it into the molded article. At this time, the monomer copolymerized with this also has the function of lowering viscosity and increasing processability.

The curing temperature of this resin varies depending on the type of copolymerized crosslinked product, but is preferably 60 to 180°C, more preferably 65 to 170°C. If this curing temperature is below 60°C, the reaction rate of copolymerization curing will be extremely slow, and 1
If the temperature exceeds 80° C., significant heat generation may occur, causing foaming, non-uniform reaction, or (1) an increase in transmission loss. In order to completely cure the resin after the above-mentioned curing, annealing may be performed at a temperature equal to or higher than the above-mentioned curing temperature.

The double-terminated acrylic-modified hydrogenated polybutadiene resin before copolymerization and curing used in the production of the crosslinked product used in the present invention and the monomers forming the copolymerization and crosslinked product are of sufficiently high purity. Preferably, it is used through a filter.

The sheath layer is made of various fluorine-containing resins, such as r'FA, FEP, and fluorine-modified polymethyl methacrylate, which have heat resistance of 150°C or higher and are 3% smaller than the copolymer cured product used for the core. Modified products etc. are used.

Furthermore, it goes without saying that the plastic optical fiber of the present invention may further be provided with a suitable coating on the outside thereof, or may be provided with a tension member.

(Example) Next, the present invention will be explained in more detail based on Examples.

Examples 1 to 7 Sufficiently purified double-end acrylic-modified hydrogenated polybucdiene resin (NISSOTEAI-1000 manufactured by Nippon Soda), polyfunctional monomers and monofunctional monomers shown in Table 1 were added, and dicumenyl peroxide was added. After mixing and thoroughly defoaming, the mixture was introduced into a PFA tube with an inner diameter of 1 mm and an outer diameter of 2 mm. The introduction distance is 12m. While introducing the mixture under pressure into the tube into which the resin was introduced, the mixture was heated at 90°C for 2 hours.
Curing was completed by heating for 4 hours and further heating at 130° C. for 10 hours. The transmission loss of the obtained fiber and the transmission loss after being held at 150° C. for 48 hours were measured, and the results are shown in Table 1. A test was also conducted to wrap the wire around a rod with a diameter of 10 mm to see if it would break. These results are also shown in the same table.

Comparative Examples 1 to 4 Add sufficiently purified polyfunctional monomers and monofunctional monomers shown in Table 1, further mix dicumenyl peroxide, and after thoroughly degassing, form a PFA duplex with an inner diameter of 1 mm and an outer diameter of 2 mm. Introduced.

The introduction distance is 12m. The above mixture was introduced under pressure into the tube into which the resin had been introduced, and the mixture was heated at 90° C. for 24 hours, and then further heated at 130″C for 10 hours to complete curing. In the same manner as Examples 1 to 7, The transmission loss of the obtained fiber and the transmission loss after being held at 150°C for 48 hours were measured, and the results are shown in Table 1.
A test was conducted on the Omm rod to see if it would break. The results are shown in the same table.

(Effects of the invention) By using a resin whose essential component is an acrylic-modified hydrogenated polybutadiene resin at both ends for the core of the plastic fiber, it has excellent heat resistance, excellent flexibility, toughness, and weather resistance. A plastic optical fiber with excellent properties can be obtained.

Claims (1)

[Claims] (1) Using a crosslinked product obtained by crosslinking a double-terminated acrylic-modified hydrogenated polybutadiene resin with a monomer having one carbon-carbon double bond and/or a monomer having two or more carbon-carbon double bonds as the core component. A plastic optical fiber characterized by: