JPH0374801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical element coated with a transparent cured thermosetting resin.
This relates to an optical element that passes UL standard V-0 class.

In recent years, the development of electronics-related elements and devices has been remarkable, and the demand for plastic materials used in these devices has also increased significantly.Also, these devices are now being widely used for consumer products. As the weather ages, the ability to be flame retardant is becoming essential.

Furthermore, among these electronics-related elements, the proportion of photoelectric conversion elements and devices such as LEDs, photocouplers, liquid crystal transparent electrodes, electroluminescence electrodes, solar cells, and photosensors is increasing. Since these elements are optical elements, coating resins used for protection and other purposes are basically required to have so-called transparency to transmit light. For this reason, in order to make these elements flame retardant, it is necessary to impart flame retardancy to the cured resin without impairing transparency, which has been thought to be an almost impossible technique.

In reality, plastic-encapsulated ICs, hybrid ICs, relays,
Despite the fact that electronics-related elements such as capacitors have achieved flame retardancy, optical elements are currently left alone.

Generally, epoxy resins are widely used as resins used as electronics-related materials from the viewpoint of electrical properties and moisture resistance.
Acid anhydride-based or phenol novolac-based epoxy resin containing atoms involved in flame retardancy such as halogen, phosphorus, and nitrogen is placed with a large amount of flame-retardant filler represented by oxides such as antimony oxide or inorganic salts. , a curing agent, and an accelerator are used to harden it, but in this method, flame retardant V-0
Although a cured product of high quality can be obtained, the transparency is completely impaired, making it completely impossible to apply this method to optical elements.

On the other hand, as is well known, there is a method for sealing cured acid anhydride cured liquid epoxy resins used in LEDs, etc., but although this method has transparency, no consideration has been given to flame retardancy. This is the current situation.

In view of these current circumstances, the inventors of the present application have conducted intensive studies to obtain an optical element that exhibits excellent flame retardancy while maintaining the transparency of epoxy resin, and have discovered that this can be achieved by adding a special antimony compound.The present invention has been developed. reached.

That is, a solvent-free resin compound containing a liquid resin obtained by heating and melting a solid halogenated epoxy resin with a liquid epoxy, a liquid polybasic carboxylic acid anhydride, a curing accelerator, and an organic antimony compound is heat-cured. A flame-retardant V-0 class optical element sealed with the cured product obtained by the above method was obtained.

The halogenated epoxy resin used in the present invention includes brominated bisphenol epoxy resin,
All halogen-substituted epoxy resins such as glycidyl ethers such as brominated phenol novolacs and cresol novolacs can be used. Generally, these epoxy resins are solid at room temperature, so these resins are then heated and mixed to form a liquid epoxy resin. At this time, it is important to achieve the present invention that the melt remains liquid when cooled to room temperature. It is. For this reason, it is desirable that the epoxy resin used has a low viscosity.

These resins include 2,2'bis(4-hydroxydiphenyl)propane, bis(4-hydroxyphenyl)methane, resorcinol, glycidyl ethers of polyhydric phenols such as hydroquinone, and 2,2'bis(4hydroxyhexyl)propane. Glycidyl ether of hydrogenated compounds of polyhydric phenols such as phenol novolak, cresol novolak, etc., vinylcyclohexene oxide, dicyclopentadiene diepoxide, limo diepoxide, (3',4'-epoxycyclohexylmethyl) Alicyclic epoxy resins such as -3,4-epoxycyclohexanecarboxylate, (3,'4'-epoxy6'methylcyclohexylmethyl)-3,4epoxy6methylcyclohexanecarboxylate, glycidyl phthalate, glycidyl tetrahydrophthalate , glycidyl esters such as glycidyl hexahydrophthalate, glycidyl ether esters such as p-oxybenzoic acid glycidyl ether, heterocyclic epoxy resins such as triglycidyl isocyanurate, diglycidyl dimethyl hydantoin, ethylene glycol, glycidyl, triglycidyl Glycidyl ethers of aliphatic alcohols such as methylolpropane and pentaerythritol. It is also possible to use these resins in combination.

Further, examples of organic antimony compounds used in the present invention include triphenylstibine, dibromotriphenylstibine, dichlorotriphenylstibine, tri(paramethylphenylstivine), di(trichloroacetoxy)triphenylstibine, etc. These organic antimony compounds act as flame retardant imparting agents, and can be used alone, but are preferably used in an amount of 5 to 30 parts by weight per 100 parts by weight of the epoxy resin.

This is because if the amount exceeds 30 parts by weight, the transparency of the cured product will be impaired, and furthermore, the glass transition temperature will decrease, resulting in a decrease in physical properties such as a decrease in heat resistance, and if it is less than 5 parts by weight, the flame retardance will decrease. The curing agent is preferably liquid and does not color during curing; examples thereof include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, trimellitic anhydride, and pyromellitic anhydride. and mixtures thereof. Furthermore, examples of curing accelerators include tertiary amines, imidazole, and 1,8 diazabicycloalkanoic acids. Additionally, additives such as antioxidants and coloring inhibitors can be added to the resin composition as needed.

The optical element is sealed using the solvent-free liquid epoxy resin thus obtained.

As a sealing method, in the case of LEDs, etc., the so-called cast method is used, in which resin is injected into a removable container, the element is immersed, and the mold is removed after heating and hardening.In the case of photo couplers, etc., the resin is dripped. Various methods can be applied, such as the so-called dropping method for curing, and the so-called coating method for liquid crystal transparent electrodes, etc.

The device obtained according to the present invention is coated with a cured resin layer made flame retardant by the action of a halogenated epoxy resin and an organic antimony compound, so it is a V-0 class flame retardant product and has excellent transparency. It was a coated element of great industrial significance, as it did not impair optical properties because of the coating.

Examples are shown below.

Example 1 Brominated bisphenol A type epoxy resin
100 parts by weight Alicyclic epoxy resin (Celoxide 2021 manufactured by Daicel Chemical Industries, Ltd.) 100 parts by weight Brominated bisphenol A 30 parts by weight Triphenylstibine 45 parts by weight Antioxidant 2 parts by weight The above mixture was heated at 80°C. The mixture was mixed and stirred using a flask for 1 hour to obtain a uniform liquid composition. Although this product was cooled to room temperature, it remained a fluid composition with fluidity.

Next, 70 parts by weight of methyl hydalophthalic anhydride and 2.0 parts by weight of 20 parts by weight of 1,8 diazabicycloalkane were mixed with 100 parts by weight of the above blend to obtain a blended composition.

In order to examine the properties of the obtained compound, it was cured by a casting method at 130°C for 1 hour, and after demolding, it was heated at 125°C for 16 hours to obtain a resin plate with a thickness of 3 mm. The transmittance (total visible light transmittance) of the cured product is 87%, and the flame retardant test is UL
-94 standard passed V-0.

The formulation was then applied to polymethylpentene LEDs.
The resin was injected into a casting mold, and the LED element was immersed and cured under the above curing conditions. The obtained coated LED device was comparable in luminous intensity to conventional epoxy resin cured product coated products, and was also an excellent flame retardant device that did not cause ignition at all.

Example 2 The compound obtained in Example 1 was applied to a thickness of 200 μm excluding the electrode portion on a photoelectric conversion device formed from an indium to tin thin film electrode formed on a polyimide film and an amorphous silicon thin film. Cure for 16 hours. Although the photoelectric conversion efficiency was 20% lower than that without the coating, the coating had sufficient transparency for practical use, and the coating layer was a flame-retardant element that did not catch fire at all.

Claims (1)

[Claims] 1. An optical element coated with a cured transparent thermosetting resin, in which the cured product is a liquid resin obtained by blending a solid halogenated epoxy resin with a liquid epoxy resin, or a liquid polyester resin. Basic carboxylic acid anhydride, curing accelerator, formula [formula] (wherein X is a halogen atom, an oxygen atom, an ester group,
R is a hydrogen atom or a methyl group, and n is 0 or 2
1. A coated optical element characterized in that it is a cured product obtained by heating and curing a liquid resin compound containing as a main component an organic antimony compound represented by the following integer.