DD212742A1 - METHOD FOR PRODUCING POLYMER ALLOYS FROM POLYMETHYL METHACRYLATE - Google Patents

Abstract

The invention relates to a process for the preparation of polymer alloys of polymethyl methacrylate and polyester ethers, resulting in materials with special property combinations. It is the object of the invention to produce transparent polymer alloys whose mechanical properties can be selectively varied by modifying crosslinked polymethyl methacrylate according to the invention by means of crosslinked polyester ethers. The object is achieved by reacting methyl methacrylate with ethylene glycol bismethacrylate in the presence of the liquid spiroorthoester of the formula 3 and the bis (spiroorthoester) d. Formula 4 polymerized simultaneously. The initiators used are Et 2 O deep + SbCl 6 deep and free radical generators such as dibenzoyl peroxide or benzil dimethyl ketal. The polymerization can be carried out thermally or photochemically. The mechanical properties of the polymer alloys prepared according to the invention can be selectively varied by using the spiroorthoesters 3 and 4 variably in percentage molar ratios greater than 70:30 and less than 95: 5. The polymer alloys obtained according to the invention are applicable in the optical industry, in particular as materials in which value is placed on transparency, flexural strength and flexibility as well as good mechanical workability.

Description

245925

additional registration

Title of the invention

"Process for the preparation of polymer alloys from polyethyl methacrylate"

Application d ^ r invention

The invention relates to a process for the preparation of polymer alloys of polymethyl methacrylate and polyester ethers according to WP CO 8G / 239 123/1, wherein materials with special property combinations arise. The polymer alloys obtained according to the invention can be used in the optical industry, in particular for purposes where value must be given to transparency, flexural strength and flexibility. Their good mechanical workability makes them suitable for manufacturing processes. Due to the low viscosity of the monomer mixtures and the significantly extended processing time, it is ideal for integration into technological processes, for example the production of moldings. They can also be used as photocurable adhesives for many purposes.

Characteristic of the known technical solutions

economically favorable synthesis possibilities of the monomers as well as the property combinations of V-resistance to weathering,

U. QtL 1982-054687

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Transparency and colorlessness of the polymers in conjunction with relatively good mechanical properties opened up the polyethacrylates to a large extent characteristic fields of application,

However, methacrylate homopolymers or copolymers with acrylic esters, which are essentially prepared by free-radical polymerization, have some disadvantages and limit their range of application. In particular, breakage susceptibility under impact stress, brittleness at low temperatures and a lack of flexural strength have to be mentioned. "The production of biphasic polymers has partially remedied these deficiencies and improved the mechanical properties. In this case, graft polymers based on butadiene / styrene / methyl methacrylate were used as the elastic phase, while the carrier phase (matrix) was a copolymer of methyl methacrylate and styrene or of these two monomers and acrylonitrile. The inadequate transparency of these two-phase polymers and the high volume contraction occurring in the polymer formation process, which can be known to assume values of more than 20 % , proved to be disadvantageous. According to WP CO 8G / 239 123/1, methyl methacrylate is used in combination with ethylene glycol bismethacrylate in the presence of a monofunctional spiroorthoester alone or in combination with a bis (spiroorthoester) solvent-free with a Initiatcrsystem consisting of Et ₃ O SbCl ₆ "and dibenzoyl peroxide thermally polymerized simultaneously at 80 - 100 ⁰ C. It is also possible, when using a suitable radical photoinitiator instead of dibenzoyl peroxide, the initiation the radical methacrylate polymerization by UV irradiation at room temperature and perform the Spiroorthoesterpolymerisation in a subsequent step thermally as described above transparent, and the volumetric shrinkage occurring in the methyl methacrylate polymerization can be reduced from 21 to 13.3 % , limitations on the applicability of this method

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but result from the use of 2-Phenoxymethyll "4,6-trioxa-spiro [4.4] -nonane as monofunctional spiroorthoester component · This monomer is a good crystallizing compound which melts in the range of 65-70 ° C and in methacrylate mixtures at room temperature is only slightly soluble. The latter restricts the possible applications of the monomer compositions according to WP CO 8G / 239 123/1, since the monofunctional spiroorthoester dissolves well in the methacrylate mixtures used in the heat but crystallizes out of the solution at room temperature too quickly. This leads to a reduction of the processing time as well as processing deficiencies, for example, often to segregation at the beginning of the Polymsrisationsprozesses, which are ultimately the cause of inhomogeneities of the polymer body. By combination with the difunctional spiroorthoester 2,2-bis- (1.4.6-trioxa-spiro [4.4] nonane-2-methyloxyphenyl) -propane in the mass ratio 1: 1 it is possible, the. However, to effectively suppress crystallization tendency of the monofunctional spiroorthoester, the long-term stability of the complete monomer mixtures remains unsatisfactory. Increases in the proportion of monofunctional spiroorthoester again cause the mentioned negative processing properties, so that it is preferably bound to the stated mass ratio · A gradation of the mechanical properties of the resulting polymer alloys by gradually increasing the mass fraction of the monofunctional over the difunctional Spiroorthoester is not possible in practical use , In addition, the necessary high proportion of bis (spiroorthoester) is economically unfavorable, since this component with respect to synthesis and purification requires considerably more effort than, for example, 2-phenoxymethyl-l.4.6-trioxaspiro [4.4 -nonane.

Object of the invention

It is the object of the invention to develop a method which makes it possible to produce transparent polymer alloys whose mechanical properties can be selectively varied.

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in that crosslinked polymethylniethacrylate is modified according to the invention by means of crosslinked polyester ether. The monomer mixtures used have low viscosity and can be used for a long time (> 24 hours) without segregation or partial crystallization. A further object of the invention is to further reduce the reduction in volume shrinkage which can be achieved according to WP CO 3G / 239 123 / i in the case of the methacrylate polymerization with the same spiro-ortho residue fraction.

Explanation of the essence of the invention

According to the invention, this object is achieved in that instead of the crystalline spiroorthoester 2-phenoxymethyl-1,4,6-trioxa-spiro [4.4] -nonane a 2-substituted 1.4.6-trioxa-spiro [4.4] nonane with an alkyl, aryl, aralkyl, cycloalkyl, alkyloxymethyl, Aralkyloxymethyl- or Cycloalkyloxymethyl substituent in the 2-position, which is liquid and low viscosity at temperatures below 30 ⁰ C and has a good solvent power for all other constituents of the monomer mixture , Preferably, 2-substituted 1,4-S-trioxa-spiro [4.4] nonane 2-isobutyloxymethyl-l.4.6-trioxa-spiro [4.4] -nonane of the formula 3_ is used.

H ₂ C CH-CH ₀ -O-CH I 2 _O -CH-CH _O 2 j 3 ° X CH CH ₃ = \ H ₂ C CH ₂ . formula / " __ CH__ H ₂ C- CH-CH ₀ -O- ^ _ / "R \ _ о ^0V I CH ₂ CH ₂ Formula 4 -0-CHp-GH H ₂ C h ₂ c

₀ 2

The spiroorthoester 3_ is in accordance with VVP

from isobutyl glycidyl ether and ^ -butyrolactone synthesizable, good to clean by distillation and an excellent solvent for the difunctional spiroorthoester 2,2-Dis - (! • 4,6-trioxa-spiro [4.4] nonane-2-methyloxyphenyl) propane of Formula £. In addition, the spiroorthoester is immiscible with the methacrylates used in the mass ratios applied according to the invention indefinitely, and the

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Preparation of the polymer alloys prepared monomer mixtures are low viscosity and stable for several days without demixing or partially crystallizing.

According to the invention monomer mixtures of methyl methacrylate I ^ and Ethylenglykolbismethacrylat 2: in the presence of Spiroorthoester 3! and 4 ^ solvent-free polymerized with an initiator system consisting of Et ₃ O ⁺ SbCl ₆ "and dibenzoyl peroxide simultaneously.

The initiation of free-radical methacrylate polymerization in polymer alloy formation is also possible in a known manner by UV irradiation with a free-radical photoinitiator, in particular with benzoin ethers, benzil dimethyl ketal or diisopropylxanthogen disulphide [P. Götze, Röhm and Haas GmbH, DBP 132 (1956)].

For the polymerization of the homogeneous mixtures of the methacrylates I ^ and 2 with the spiroorthoesters 3 and 4 Et_O ⁺ sbCl _R ~ concentrations between 0.5 and 2% by weight based on the total amount of 3_ and £ are used. The amount of dibenzoyl peroxide is advantageously based 1-C ^ mass on the amount of methyl methacrylate I. ₁

The polymerization temperature is advantageously from 80 to 100 ⁰ C.

If, on the other hand, the methacrylate polymerization is initiated with one of the photoinitiators mentioned by UV irradiation, the reaction is preferably carried out at room temperature.

The mass ratio of the mixture of the methacrylates I ^ and £ to the mixture of the spiroorthoesters 3_ and £ remains constant in accordance with WP CO QG / 239 123/1 and amounts to 1: 1. However, it is possible by means of the use according to the invention of the liquid spiroorthoester 3_ to change the molar ratio of the spiroorthoesters G $ and 4_ with one another such that the mechanical properties of the polymer alloys to be produced can be selectively varied. In particular, the proportion of the cheaper spiroorthoester ^ can be increased without adverse effects due to partial separations occurring during processing or during the polymerization process.

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According to the invention, if the percentage molar ratios of the spiroorthoester zum to the bis (spiroorthoester) größer are greater than 70:30 and less than 95: 5, and such spiroorthoester combinations are polymerized with the methacrylates I ₁ and gemäß according to the procedure described, transparent polymer alloys are formed. The mechanical properties of the thus-elasticized methacrylate networks span a wide range of elasticity. If the proportion of bis (spiroorthoester) is high, elastic, impact-resistant polymer bodies are formed, and if the proportion of spiroorthoester 3_ is increased, the mechanical properties tend to be low-elastic and flexible.

The use according to the invention of the liquid spiroorthoester 3_ reduces, in relation to comparable data when using the crystalline spiroorthoesterc 2-phencxymethyl-1,4,6-trioxa-spiro [4,4] -nonane, the resulting volume shrinkage during the polymerization process by more than 1%, is the volume contraction during the polymerization of Methacrylr.tkombinaticn used in the invention from 2i ^υηο "£ 24.8%, and it is reduced in the inventive polymer alloy formation with the Spiroorthoestern 3_ £ and to 12.2%. the measurement and calculation volume shrinkage was carried out as indicated in WP CO 8G / 239 123/1,

Exemplary embodiments Example 1

In 9.0 g of methyl methacrylate I ₁ and 1.0 g of ethylene glycol bismethacrylate 2 , 0.1 g of dibonoyl peroxide are dissolved smoothly. Furthermore, in 6.1 g of 2-isobutyloxymethyl-l »4,6-trioxaspiro [4.4] nonane 3_ and 4.8 g of 2,2-bis (1,4,6-trioxa-spiro [4.4] nonane-2 -methyloxyphenyl) -propane 4 0.2 g of Et ₀ O ⁺ SbCIc- "dissolved smoothly under gentle heating. are mixed at room temperature with stirring same mass parts of the methacrylate and Spiroorthoesterkombination and obtains a low-viscosity

-3 monomer mixture of density <£ ₂ n ⁼ 1r0287 g.cm.

The monomer mixture is polymerized for 10 hours at 80 ^° C. in a sealed vessel. You get so transparent,

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impact-resistant, in organic solvents insoluble polymer body of density C ^ = 1.171 g .cm. The resulting volume shrinkage during the polymerization process is thus 12.2 %.

Example 2

9.7 g of spiroorthoester 3_ and 2.6 g of bis (spiroorthoester) 4_ are dissolved in 12.3 g of a mixture of 90% by weight of methyl methacrylate I ₁ and 10% by weight of ethylene glycol bismethacrylate. To this is added 220 mg of Et ₃ O ⁺ SbCl ₆ 'and 150 mg of dibenzoyl peroxide, dissolved with stirring and gentle warming and polymerized the clear solution for 8 hours at 100 ⁰ C. After completion of the polymerization, transparent, low-elastic and flexible polymer body are obtained in are insoluble in organic solvents and their density <≤ _2Q »is 1.154 g.cm. The density of the monomer mixture is ^ ₂ n ³ 1 »QH & g.cm"",

₂ n the resulting volume shrinkage therefore 12.3 %.

Example 3

2.0 g of a mixture of 80 mol% of spiroorthoester 3> and 20 mol% of bis (spiroorthoester) 1 are dissolved in 2.0 g of a mixture of 90% by weight of methyl methacrylate I ₁ and 10% by weight of ethylene glycol bismethacrylate. To this is added 32 mg of Et ₃ O ⁺ SbCl ₆ "and 100 mg of benzil dimethyl ketal and triggers the initiators with stirring. The clear monomer mixture is transferred to a quartz vessel and irradiated in a carousel apparatus with a mercury immersion lamp for 60 minutes at 20 ⁰ C and then for 8 hours heated to 80 ⁰ C. Obtained transparent, elastic polymer body of density <p ₂₀ = 1.165 g.cm ", which are insoluble in organic solvents.

Claims (3)

245925 claim for invention 1. A process for the preparation of polymer alloys of PoIymethylmethacrylat and polyester ethers according to WP CO 8G / 239 123/1 characterized in that instead of the crystalline Spiroorthoesters 2-phenoxy-ethyl-l .4 .6 ~ trioxa = -spiro- [4.4] -nonane a liquid 2-substituted 1,4,6-trioxa-spiro [4 _# 4] -nonane is used with an alkyl, aryl, aralkyl, cycloalkyl, alkyloxymethyl, aralkyloxymethyl or cycloalkyloxymethyl substituent in the 2-position « 2 · Process according to item 1, characterized in that the 2-substituted 1,4,6-trioxa-spiro-C4,43-nonane is preferably 2-isobutyloxymethyl-l.4.6-trioxa-spiro [4.4] -nonane of the formula _3 . 3 · Process according to item 1, characterized in that the spiroorthoesters 3_ and A ^ are used variably in percent molar ratios of greater than 70:30 and less than 95: 5 in admixture with the methacrylates I ₁ and 2 .