DD225856A3 - LIGHT HEALTHY ESTERETHER OPTIC ADHESIVES - Google Patents

Abstract

The optical adhesives according to the invention are used for bonding finished optical components to one another with high accuracy requirements for optical systems. In addition, they can serve for the bonding of different materials, for example of metals with optical assemblies. It is an object of the invention to produce by light hair-hardenable ester-ether optical adhesives by way of the stepwise bulk polymerization of (1,3-dioxolan-4yl) methyl methacrylates, acrylates. In the first stage, an immediate fixation should be achieved by short-term irradiation of the adjusted optical components. In this case, the optical components connected by the optical adhesive should remain thermally separable over a longer period of time, and the optical adhesive should be removable from the separate optical components at this stage by organic solvents. The final fixing is to take place in the second stage by thermal polymerization or photopolymerization. The object is achieved by using solutions of (2,2-dialkyl-1,3-dioxolan-4yl) -methyl methacrylate with a free-radical-forming photoinitiator and a suitable cationic initiator stepwise alone or in combination with 2,2-bis (1, 4,6-trioxa-spiro-4,4-nonane-2-methyloxyphenyl) -propane, (2,2-bis-p-2-hydroxy-3-methacryloxypropoxy) phenyl propane). Application: optical industry, optical media.

Description

Field of application of the invention

The invention includes air-curable ester ether optical adhesives. These are liquid ester ether monomers

alone or to their homogeneous mixtures with cationically or radically polymerizable monomers or oligomers and suitable initiators.

The polymerization of the monomers occurs by photoinitiation, whereby the reaction can be controlled to proceed in two stages. In the first stage, the photofixing is carried out by radical polymerization, in the second stage, the complete curing by cationic ring-opening polymerization occurs.

The optical adhesives of the invention are used for bonding finished optical components with each other with high accuracy requirements for optical systems. They can also be used to bond different materials, such as metals with optical assemblies.

Characteristic of the known technical solutions

Polymethyl methacrylates and polymethyl acrylates with photocrosslinkable 2,2-dialky-1,3-dioxolane groups are already known in the literature. Y.Nakashima and F.Fukuda (J. Polymer, Polym.Chem., Es, 17,245 (1979)) polymerize (2-ethyl-2-methyl-1,3-dioxolan-4-yl) methyl acrylate and (2-methyl- 2-phenyl-1,3-dioxolan-4-yl) methyl methacrylate in benzene at 60 ^° C. with benzoyl peroxide in sealed ampoules with exclusion of oxygen, and produce films by pouring the acetone polymer solutions on UV radiation of the transparent soluble polymer films alone or with Benzoin and cobalt naphthenate over a period of more than 3 minutes then result in increasing cross-linking of the polymer films, and it is concluded from a new band in the IR spectrum at 3450 cm "'that hydroperoxides are formed upon photocrosslinking.

T.Ouchi, S.Nakamura, M.Hamada and M.Oiwa, J. Polym. Be. Polym. Chem. Ed., 13, 455 (1975) and J. Polym. Polym. Chem. Ed., 14, 2835 (1976) investigated the photopolymerization of styrene with 2-vinyl-1,3-dioxolane and 2-vinyl-4-hydroxymethyl-1,3-dioxo.lan. For this purpose, the monomers were polymerized in the presence of AIBN in the block at 65 ° C and the subsequent crosslinking of the polymers in dioxane solution at 40 ° C by irradiation with a high pressure mercury lamp. The subject of this work is mechanistic investigations of the photoreaction. It is shown that H abstraction and subsequent 3-cleavage lead to ester formation and crosslinking.

In Houben Weyl: Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart 1963, Vol. 14 / 2,467, the stepwise thermal polymerization of (2,2-dimethyl-1,3-dioxolan-4yl) methyl methacrylate with benzoyl peroxide and the subsequent BF ₃ Et ₂ O initiated crosslinking in toluene solution described.

The publications mentioned, which include a photoreaction, have in common that d '>*>. Polymerization of the olefinic double bond takes place thermally free radical in solution and that the subsequent photocrosslinking - also radically - by prolonged irradiation with UV light on films cast from polymer solutions or in solution. Such a procedure is not suitable for the use of (1,3-dioxolan-4yl) methyl methacrylates or acrylates as photo-curing optical adhesives, since it is known that vaporizing the solvent causes blistering and thus reduced adhesion of the optical adhesive. In addition, the use of solvents brings additional occupational safety and economic disadvantages.

Object of the invention

It is an object of the invention to produce light-curable ester-ether optical adhesives by the stepwise bulk polymerization of (1,3-dioxolan-4yl) methyl methacrylates. In the first stage should be achieved by brief irradiation of the adjusted optical parts immediate fixation. In this case, the optics components connected by the optical adhesive are to remain thermally separable over a relatively long period of time, and the optical adhesive should be removable from the separate optical components at this stage by organic solvents. The final fixation of the cemented parts should be carried out in the second stage by thermal polymerization or photopolymerization. Furthermore, the invention pursues the goal of bulk polymerization in the presence of other monomers or

To perform oligomers, so as to be able to vary the physicochemical properties of the optical polymers such as flexibility, breaking strength, tensile stress, compressive stress.

Explanation of the essence of the invention

The object of the invention is to produce a light-curable ester-ether optical adhesive by way of stepwise bulk polymerization of liquid monomers or their homogeneous mixtures with further additives. This object is achieved by reacting solutions of (2,2-dialkyl-1 _/ 3-dioxolan-4yl) methyl methacrylate or (2,2-dialkyl-1,3-dioxolan-4yl) methyl acrylate with a radical-forming photoinitiator and polymerized stepwise to a suitable cationic initiator.

As (2,2-dialkyl-1-3-dioxolan-4yl) methyl methacrylate or methyl acrylate, the 2,2-dimethyl compounds are particularly suitable. They have excellent dissolving power for a wide variety of initiators and monomers or oligomer additives, have a low vapor pressure, are largely odorless and easy to handle. They are storage stable even without stabilizer for weeks and months, without an increase in viscosity due to polymerization occurs.

Suitable free-radical photoinitiators are the compounds known per se, such as benzoin and benzoin ethers, such as benzoin methyl ether, benzoin isopropyl ether, and also benzil and benzil ketals, in particular benzil dimethyl ketal. Suitable cationic initiators are: arylonium salts such as Ph ₂ J ⁺ X "where Y" = AsF ₆ , BF ₄ , SbF ₆ or PF ₆ (see A. Lewis, Polymer 19 (1978/1217), where appropriate sensitizers Further, particularly suitable cationic initiators are oxonium salts such as Et ₃ O ⁺ SbCl ₆ "and Et ₃ O ⁺ BF ₄ " The optical adhesive according to the invention is used, for example, for the bonding of optical parts: 50 mg of benzoin methyl ether and 30 mg of Et ₃ O ⁺ SbCl ₆ "are dissolved in 5 g (2,2-dimethyl-1,3-dioxolan-4-yl) methyl methacrylate and the solution is placed between the optical parts to be bonded and heated with a high-pressure mercury lamp (HBO 200) distance of 18-20cm exposed. the fixing is carried out within a period of irradiation of 120 see. After that, the bonded optical member is heated to 60-80 ⁰ C. for 5 hours and is then ready for use.

If Et ₃ O ⁺ SbCl ₆ "is replaced by + Ar-J-ArS-PF ₆ " in the same monomer solution, the thermal aftertreatment of the bonded optical parts can be dispensed with. Instead, the prefixed optical parts are exposed after 2 to 10 minutes. The thereby formed from the iodonium salt HPF ₅ then polymerized crosslinking cationic dioxolane ring of the polymer. The optical components are then ready for use after a storage time of 10-20 hours.

The optical adhesive according to the invention can be optimally varied with regard to stress-free bonding and climatic stability of the optical adhesive polymer layer. Excellent for this purpose is the combination with the spiroorthoesters of the formula 1 and / or the formula 2 (see DDR application WP C 08 G / 151 314 and WP C08 G / 234816/5). Formula 1:

Formula 2:

The optical adhesive according to the invention is then applied, for example, as follows for the bonding of optical parts: In 5.0g (2,2-dimethyl-1,3-dioxolan-4yl) methyl methacrylate 1.5 g of bis (spiroorthoester) of formula 2, 50mg benzoin methyl ether and 50mg et ₃ O ⁺ SbCl ₆ dissolved ". the solution is placed between the adherend optical parts and irradiated with a high pressure mercury lamp through the glass of the optical parts. After 60see the optical parts are fixed. They are then heated to 6O ⁰ C for 5 hours and are then ready for use ,

If it is possible to dispense with the solubility of the optical cement layer incorrectly cemented and separated by thermal treatment optics components, then a faster photofixation of the two described optical adhesives according to the invention by adding (2,2-bis p- (2-hydroxy-3-methacryloxypropoxy) phenyl propane) "DDGE-bis-MMA" (addition product of diandiglycidyl ether with 2 mol of methacrylic acid) is possible, the concentration is advantageously up to 30% and the fixing times are thus shortened to 2-30 seconds.

Apart from the spiroorthoesters of the formulas 1 and 2 and the "DDGE-bis-MMA", further additives can be added to the dioxolanemethyl methacrylate, oligomeric polyesters being particularly suitable for this purpose.

embodiments

Example 1 to 5

A principle for the bonding of optical components is made of the following substances:

5.0 g (2,2-dimethyl-1,3-dioxolan-4-yl) methyl methacrylate

0.005 g benzoin methyl ether

0.02g Et ₃ O ⁺ SbCl ₆ "

The solution is added without further additives or with the additives of Table 1 as a homogeneous solution between the to be bonded

Optical parts are brought and coated with the unfiltered light of a high pressure mercury lamp (HBO 200) at a distance of 18-20cm. The time necessary for fixation is given in Table 1.

Table 1

Example Addition Fixing time Therm. Separating total

sec availability shrinkage

1 120 80 ⁰ C 8.0%

2 1.5 g bis (spiroortho 60 8O ⁰ C 2.0%

ester) 2

3 1.0 g hydroxymethyl 60 90 ⁰ C 4.5%

methacrylate

4 0.5 g "DDGE-bismethacrylic 30 120 ⁰ C 4.0%

lat "

5 1.5 g polyester (M900- 60 105 ⁰ C 5.5%

1200, SZ 29-33)

tetrahydrophthalic

acid / butylene glycol 4.3

The optical components bonded with the optical adhesives (Examples 1 to 5) can be separated by thermal treatment for 5-6 minutes. The polymer adhesive of Examples 1, 2 and 5 is soluble in acetone, chloroform, the optical adhesive of Examples 3 and 4 can be swelled by acetone or chloroform and then completely peels off the optical components. The complete cure of Examples 1-5 is carried out by heating at 60-70 ° C for 6 hours. Thereafter, the bonded optical components are no longer thermally separable

 Example 6:

5.0 g (2,2-dimethyl-1,3-dioxolan-4-yl) methyl methacrylate 0.05 g benzoin methyl ether 0.5 g DDGE bis methacrylate 0.02 g +

0.01 g acridine orange. , , , ,

The solution is placed between the optical parts to be bonded and exposed to the unfiltered light of a high-pressure mercury lamp (HBO 200) at a distance of 18-20 cm. The fixation time is 30see. For complete curing is exposed for 5 minutes and stored at room temperature for 12 hours. Thereafter, the optical parts are operational.

Claims (9)

Invention claims: 1. Light-curable ester-ether optical adhesives, characterized in that solutions of (2,2-dialkyl-1,3-dioxolan-4yl) methyl methacrylate or (2,2-dialkyl-1, S-dioxolan ^ yDmethylacrylat with a radical-forming photoinitiator and a cationic initiator are polymerized stepwise. 2. optical adhesive according to item 1, characterized in that the dialkyl groups are preferably identical and denote methyl groups. 3. An optical adhesive according to item 1, characterized in that are used as the radical-forming photoinitiator for the partial curing benzoin or benzoin ethers such as preferably benzoin methyl ether or benzil or benzil dimethyl ketal. 4. optical adhesive according to item 1, characterized in that as cationic initiators for the final curing coordinate shifts of .Lewissäuren, in particular PF ₃ · Et ₂ O; BF ₃ -Ethanolaminkomplexe, oxonium salts, in particular Et ₃ O ⁺ SbCI ₆ "are used and that heat is supplied to the polymerization system. 5. Optical adhesives according to item 1, characterized in that cationic photoinitiators are used, in particular aromatic halogen onium salts of the elements of the greeting Va of the periodic system and that light is supplied to the polymerization system. 6. optical adhesive according to item 1, characterized in that for the stepwise polymerization 1 to 10 wt .-% of the free-radical and cationic initiator are added. 7. optical cloth according to item 1, characterized in that homogeneous solutions with spiroorthoesters in particular with 2-phenoxymethyl-1.4.6-trioxa-spiro-4,4-nonane (Forms! 1) or 2,2-bis (1.4.6.-trioxa -spiro-4,4-nonan-2-methyl-oxyphenyl) -propane (Formula 2). 8. An optical adhesive according to item 2, characterized in that 10-50 wt .-% of Spiroorthoesters of formula 1 or 2 are used. 9. optical adhesive according to item 1 and 2, characterized in that a higher functional acrylate or methacrylate component is contained in the mass fraction of 1-20% and preferably a diacrylate / dimethacrylate of diandiglycidyl ether (2,2-bis p- (2-hydroxy-3 methacryloypropoxy) phenyl propane).