WO2005019278A1

WO2005019278A1 - Color-stable polyvinyl acetal, method for the production and the utilization thereof

Info

Publication number: WO2005019278A1
Application number: PCT/EP2004/008673
Authority: WO
Inventors: Bernd Papenfuhs
Original assignee: Kuraray Specialities Europe Gmbh
Priority date: 2003-08-19
Filing date: 2004-08-03
Publication date: 2005-03-03

Abstract

The invention relates to a mixture containing, in relation to its total weight, the following: A.) at least 50.0 weight percent of at least one polyvinyl acetal that is obtained in accordance with a method in which a polymer (A1) that, in relation to its total weight, contains a) 1.0 to 1000.0 weight percent of structural units of formula (1), b) 0 to 99.0 weight percent of structural units of formula (2), c) 0 to 70.0 weight percent of structural units of formula (3) is reacted with at least one compound (A2) of formula (4), B.) 0.001 to 2.0 weight percent oxalic acid and C.) 0.001 to 2.0 weight percent of at least one antioxidant, wherein the radicals R1 to R8 are defined according to the description. The invention also relates to a method for the production of the inventive mixture and to its possible application areas.

Description

Color stable polyvinyl acetals, process for their preparation and their use

The present invention relates to a polyvinyl acetal-containing mixture, process for its preparation and its use.

Polyvinyl acetals, which are usually obtained by acetalization of the corresponding polyvinyl alcohols, have been known for a long time and are thermoplastic processed in large quantities and, in particular, extruded to form foils which, among other things. a. are characterized by excellent mechanical properties and are used as intermediate layers in single or multi-layer laminated glasses, preferably for vehicle glass panes, architectural glasses for the construction sector and bulletproof glass panes.

A disadvantage of polyvinyl acetals is their high sensitivity to oxidation, in particular in the heat, compared to other technically usable polymers, and their instability or sensitivity to hydrolysis towards acids. Advantageously, polyvinyl acetals are therefore stabilized before or during their, preferably thermoplastic, processing by adding antioxidants, preferably phenols, and a small amount of alkali metal hydroxide is added to prevent acid hydrolysis.

Since foils made of polyvinyl acetal often have too strong adhesion to inorganic glasses, the polyvinyl acetal can be used to reduce this adhesion before or during the production of the films, adhesion-reducing substances, for example salts, such as, for. As potassium acetate, are added. The addition of such generally alkaline non-stick agents and the high melt temperatures to be used in the extrusion of generally> 180 ° C. are known to lead to considerably discolored plasticized polyvinyl acetal films. Numerous attempts and measures have therefore become known which reduce the discoloration of Aimed at polyvinyl acetal films. The additional stabilization of polyvinyl butyral by a benzotriazole derivative is known from US Pat. No. 3,823,113. DE-PS 3347040 and DE-OS 3228076 describe the use of a combination of a phenolic antioxidant and a phosphite for polyvinyl butyral stabilization. However, it has been shown that only small or unsatisfactory stabilization results can be achieved with the methods described in the abovementioned publications, the polyvinyl acetal stabilization with phosphite in particular being problematic under long-term conditions. As is known, under the action of alkali, phosphites tend to hydrolysis and thus to the release of phosphorous acid, which can then lead to the degradation of the polyvinyl acetal or can contribute to its degradation.

As is known, the primary stabilizer in polyvinyl acetal stabilization is usually a phenolic antioxidant, preferably a sterically hindered substituted phenol. From DE-PS 2208167 in the ortho or para position to the phenolic OH group substituted phenols of this type and their use for polyvinyl acetal stabilization are known, generally mononuclear phenols, such as. B. isobornylxylenol or 2,6-di-tert-butyl-4-methylphenol, can be used.

When using these phenols, such as. B. isobornylxylenol, for the stabilization of plasticized polyvinyl acetal films, when using the latter for laminated glass production according to the usual autoclave method, there is also edge discoloration in the finished glass composite, which is very unsatisfactory and often leads to losses.

A summary of the prior art relating to the above-mentioned conventional stabilizer systems and the difficulties which arise when using them for polyvinyl acetals, in particular polyvinyl butyrals, can also be found in the publications TV Monakhova, AP Mar'in, Yu. A. Shlyapnikov Thermal Oxidation ofHighly Plasticized Poly (vinyl Butyral) Polymer Science, Vol. 35, No. 9, 1993, pp. 1271-1273 and AP Mar'in, LA Tatarenko, Yu. A. Shlyapnikov Solubility ofantioxidants inpoly (vinyl butyral) Polymer Degradation and Stability Vol. 62, 1998, pp. 507-511. In particular, they point out that the efficiency of conventional antioxidants in polyvinyl acetals is significantly lower than in polyolefins and that there is therefore a need for more effective ways of protecting polyvinyl acetals against oxidation and discoloration.

EP 0 568 999 A1 discloses a first approach to solving these problems, which, for the stabilization of polyvinyl acetal, uses polynuclear phenols of the formula (I)

wherein m is 1 to 4 and n is 1 or 2, wherein R ¹ and R ² , which may be the same or different, is hydrogen, a linear or branched one

or (C ₄ -C ₈ ) cycloalkyl, in which R represents hydrogen or a methyl radical, in which R ⁴ , which can be monovalent or divalent, is a (CrCi8) alkyl radical if n = 1, or -CpH _2p - with p = 1 to 8, preferably p = 2, if n = 2, optionally in combination with synergistic nitrogen-containing, sulfur-containing or phosphorus-containing costabilizers, preferably of the types a) to d), proposes: a) nitrogen-containing compounds of the formula (II )

wherein R ¹ , R ² , R ³ , R ⁴ , which may be the same or different, are a (C1-C ₄ ) alkyl or a (C ₄ -C ₈ ) cycloalkyl radical, wherein R ^{5 is} hydrogen, a (C ₁ -Ci8) alkyl, (C ₁ -C ₁ 8) hydroxyalkyl, (- C ₁₈ ) alkoxy or a (C ₁ -C ₁₈ ) acyloxy radical, in which R ⁶ and R ⁷ , which can be the same or different and each one of the radicals R ⁶ or R ⁷ = H, characterize a monovalent organic radical having 1 to 30 carbon atoms, which may contain one or more heteroatoms, which may be different, and may contain epoxy groups or wherein R ⁶ and R ⁷ together with the carbon atom of the piperidine ring form a monocyclic or multiple cyclic radical having up to 60 carbon atoms, which may be branched and may contain one or more heteroatoms, which may be different, and may contain epoxy groups polymeric or copolymeric forms of compounds of the formula (JJ), b) nitrogen-containing compounds from the group aliphatic carboxylic acid hydrazides b between dicarboxylic acid dihydrazides, preferably with 2 to 12 carbon atoms, c) sulfur-containing compounds from the group di- (C ₄ -C ₁₈ ) -alkyl sulfides and disulfides, thiotin compounds of the formula R _x Sn (-S-CH ₂ - COOR) _y , where x + y = 4, x, y = 1 to 3, and R = (-C-C ₁₈ ) alkyl, di- (CC ₁₈ ) - alkylthiodipropionate, d) phosphorus-containing compounds from the group of hydrolysis-resistant phosphites.

Although an improvement in thermal stability and light resistance can be achieved in this way, the provision of even better stabilizers or stabilizer systems is nevertheless desirable from a technical point of view. From the application DE 100 18 517 AI it is also known to crosslink polyvinyl acetals with oxalic acid. However, information on the protection of polyvinyl acetals, in particular against oxidative changes, cannot be found in this publication.

In view of the prior art, it was therefore an object of the present invention to provide a stabilizer system for polyvinyl acetals which does not have the disadvantages of known polyvinyl acetal stabilizers described above and which advantageously improves the thermostability and the light resistance of polyvinyl acetals. In particular, the stabilizer system according to the invention should make it possible to reduce the tendency to yellowing in the production of polyvinyl acetal films.

It was also an object of the present invention to provide a method for stabilizing polyvinyl acetals which can be carried out in a simple manner, on an industrial scale and at low cost.

It was also an aim of the present invention to show particularly suitable fields of application of the polyvinyl acetals stabilized according to the invention.

These and other tasks which are not explicitly mentioned, but which can easily be derived or inferred from the contexts discussed here, are achieved by a mixture with all the features of claim 1. Appropriate modifications of the mixture according to the invention are protected in the subclaims which refer back to claim 1 , Furthermore, a method for producing the mixture according to the invention is claimed in the process claims and the claims of the use category and the associated product claims describe particularly advantageous fields of use of the mixture according to the invention.

By providing a mixture which, based on its total weight, contains the following components: A.) at least 50.0% by weight of at least one polyvinyl acetal, obtainable by a process in which a polymer (AI) which, based on its total weight, a) 1.0 to 100.0% by weight of structural units of the Formula 1)

wherein R ^{1 is} hydrogen or methyl, b) 0 to 99.0% by weight of structural units of the formula (2)

wherein R ^{2 represents} hydrogen or an alkyl radical having 1 to 6 carbon atoms, c) 0 to 70.0% by weight of structural units of the formula (3)

wherein R ³ , R ⁴ , R ⁵ and R ⁶ , each independently of one another, contain residues with a molecular weight in the range from 1 to 500 g / mol, are reacted with at least one compound (A2) of the formula (4),

wherein R ⁷ and R ^{8 are} each independently hydrogen, COOH, COOM, an alkyl group having 1 to 10 carbon atoms or one are optionally substituted aryl groups having 6 to 12 carbon atoms and where M is a metal cation or an optionally alkylated amino cation,

B.) 0.001 to 2.0 wt .-% oxalic acid and

C.) 0.001 to 2.0 wt .-% of at least one antioxidant, it is not readily predictable to make a polyvinyl acetal-containing mixture accessible, which has an improved thermal stability and moreover an improved light resistance. In particular, the stabilizer system according to the invention enables a reduction in the tendency to yellowing in the production of polyvinyl acetal films.

At the same time, a number of further advantages result from the teaching according to the invention. These include a .:

=> The procedure according to the invention is state of the art, i. H. clearly superior to the sole use of antioxidants for the stabilization of polyvinyl acetals and leads, in particular at the same application rates of antioxidants, to polyvinyl acetal-containing mixtures with greatly improved color stability and significantly improved optical quality, in particular after thermoplastic processing.

=> According to the invention, the stabilization of polyvinyl acetals is possible in the simplest manner, on an industrial scale and at low cost.

The present invention relates to a mixture which, based in each case on its total weight, contains the following components:

A)) at least 50.0% by weight, preferably at least 60.0% by weight, suitably at least 75.0% by weight, preferably at least 85.0% by weight, in particular at least 96.0% by weight %, at least one polyvinyl acetal, B.) 0.001 to 2.0% by weight, preferably 0.01 to 1.0% by weight, advantageously 0.01 to 0.8% by weight, preferably 0.01 to 0.5% by weight %, in particular 0.05 to 0.3% by weight, oxalic acid and

C.) 0.001 to 2.0% by weight, preferably 0.01 to 1.0% by weight, advantageously 0.05 to 0.8% by weight, preferably 0.07 to 0.5% by weight %, in particular 0.1 to 0.3% by weight, of at least one antioxidant.

The polyvinyl acetal can be obtained by reacting at least one polymer (AI) with at least one compound (A2), the polymer (AI) in each case comprising the following structural units, based on its total weight: a) 1.0 to 100.0% by weight, preferably 1.0 to 99.9% by weight, basic units of the formula (1)

b) 0 to 99.0% by weight of structural units of the formula (2)

c) 0 to 70.0% by weight, preferably 0.01 to 70.0% by weight, in particular 0.01 to 60.0% by weight, structure units of the formula (3)

The respective structural units are of course different from one another, in particular in the context of the present invention the structural unit of the formula (3) does not include the structural units of the formula (1) or (2).

The radical R ¹ each independently represents hydrogen or methyl, preferably hydrogen.

The radical R ² denotes hydrogen or an alkyl radical with 1 to 6 carbon atoms, preferably an alkyl radical with 1 to 6 carbon atoms, advantageously a methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl -, tert-butyl, n-pentyl or an n-hexyl group, advantageously a methyl or an ethyl group, especially a methyl group.

The radicals R ³ , R ⁴ , R ⁵ and R ⁶ are each, independently of one another, radicals with a molecular weight in the range from 1 to 500 g / mol, advantageously hydrogen, an optionally branched, aliphatic or cycloaliphatic radical with 1 to 16 carbon atoms, which, if appropriate may contain one or more carboxylic acid, carboxylic acid anhydride, carboxylic acid ester, carboxylic acid amide and or sulfonic acid groups.

Particularly preferred structural units of the formula (3) are derived from straight-chain or branched olefins having 2 to 18 carbon atoms, (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, (meth) acrylamides and / or ethylene sulfonic acid. Here, olefins, in particular those with a terminal C-C double bond, which preferably have 2 to 6 carbon atoms, in particular ethylene, have proven to be very particularly favorable. Furthermore, structural units (3) which are derived from acrylamidopropenylsulfonic acid (AMPS) also lead to very particularly advantageous results according to the invention.

The total number of structural units of the formula (2) is preferably in the range from 0.1 to 40 mol%, advantageously in the range from 0.5 to 25.0 mol%, in particular in the range from 1.0 to 15.0 mol -%, each based on the Total number of structural units of the formula (1) and (2). According to a first preferred embodiment of the present invention, a polymer (AI) is used which, based on the total number of structural units of the formula (1) and (2), contains 1.0 to 2.0 mol% of structural units of the formula (2) , According to a second preferred embodiment of the present invention, a polymer (AI) is used which, based on the total number of structural units of the formula (1) and (2), contains 3.0 to 7.0 mol% of structural units of the formula (2) , According to a third preferred embodiment of the present invention, a polymer (AI) is used which, based on the total number of structural units of the formula (1) and (2), contains 10.0 to 15.0 mol% of structural units of the formula (2).

According to a further particularly preferred embodiment of the present invention, the polymer (AI), based in each case on its total weight, contains greater than 50.0% by weight, advantageously greater than 60.0% by weight, advantageously greater than 70.0% by weight , in particular greater than 80.0% by weight of structural units of the formula (1) and / or (2). Particularly advantageous results can be achieved with polymers (AI) which, based on their total weight, are greater than 85.0% by weight, advantageously greater than 90.0% by weight, advantageously greater than 95.0% by weight. contain in particular greater than 99.0% by weight of structural units of the formula (1) and / or (2). It has proven to be particularly advantageous according to the invention that the polymer (AI) contains more than 95.0% by weight of structural units of the formula (1).

In the context of the present invention, the polymer (AI) can have a syndiotactic, isotactic and or atactic chain structure. Furthermore, it can exist both as a random and as a block copolymer.

The viscosity of the polymer (AI) is of minor importance according to the invention; in principle, both low-molecular and high-molecular polymers (AI) can be used. Nevertheless, it has proven to be particularly advantageous in the context of the present invention that the polymer (AI) has a viscosity in the range from 1.0 to 70 mPas, preferably in the range from 2.0 to 40 mPas, in particular in the range from 2.5 to 35 mPas (measured as a 4% by weight aqueous solution according to Höppler at 20 ° C, DIN 53015).

The polymers (AI) to be used according to the invention can be prepared in a manner known per se in a two-stage process. In a first step, the corresponding vinyl ester is radically polymerized in a suitable solvent, usually water or an alcohol, such as methanol, ethanol, propanol and / or butanol, using a suitable radical initiator. If the polymerization is carried out in the presence of free-radically copolymerizable monomers, the corresponding vinyl ester copolymers are obtained.

The vinyl ester (co) polymer is then saponified in a second step, usually by transesterification with methanol, it being possible to set the degree of saponification in a manner known per se, for example by varying the catalyst concentration, the reaction temperature and / or the reaction time. For further details, reference is made to the current specialist literature, in particular to Ullmann's Encyclopedia of Industrial Chemistry, Fifth Edition on CD-Rom Wiley-VCH, 1997, Keyword: Poly (Vinyl Acetals) and the references cited therein.

According to the invention, the compound (A2) satisfies the formula (4)

The radicals R ⁷ and R ⁸ are each independently hydrogen, COOH, COOM, an alkyl group with 1 to 10 carbon atoms or an aryl group with 6 to 12 carbon atoms. These alkyl and aryl radicals can be substituted with one or more carboxyl, hydroxyl, sulfonic acid groups and / or halogen atoms, such as fluorine, chlorine, bromine, iodine. The rest of M denotes a metal cation or an optionally alkylated ammonium cation. Particularly favorable metalations are derived from elements of PSE with an electronegativity less than 2.0, preferably less than 1.5, and include in particular Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Be ²⁺ , Mg ^{2 "1 "} , Ca ²⁺ , Sr ² *, Ba ²⁺ and Al ³⁺ . The ammonium cations which are particularly expedient for the purposes of the present invention include NH ^" , H ₃ NCH ₃ ⁺ , H ₃ NC ₂ H ₅ ⁺ , H ₃ NC ₃ H ₇ ⁺ , H ₃ NC ₄ H ₉ ⁺ , H ₂ N (CH ₃ ) ₂ ⁺ , H ₂ N (C ₂ H ₅ ) ₂ ⁺ , H ₂ N (C ₃ H ₇ ) ₂ ⁺ , H ₂ N (C ₄ H ₉ ) ₂ ⁺ , HN (CH ₃ ) ₃ ⁺ , HN (C ₂ H ₅ ) ₃ ⁺ , HN (C ₃ H ₇ ) ₃ ⁺ , HN (C ₄ H ₉ ) ₃ ⁺ , N (CH ₃ ) ₄ ⁺ , N (C ₂ H ₅ ) ₄ ⁺ , N (C ₃ H ₇ ) ₄ ⁺ and N (C4H ₉ ) ₄ ⁺ .

Compounds (A2) which are particularly preferred for the purposes of the present invention include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, 2-ethoxybutyraldehyde, paraldehyde, 1,3,5-trioxane, capronaldehyde, 2-ethylhexanal, pelargonaldehyde, 3,5,5-trimethylhexanal, 2-formylbenzenesulfonic acid, acetone, ethyl methyl ketone, butyl ethyl ketone and / or ethyl hexyl ketone. According to a further preferred embodiment, glyoxylic acid HCO-COOH is used as compound (A2).

In the context of the present invention, the use of aldehydes, ie of compounds of the formula (4) with R ⁷ = hydrogen and R ⁸ = hydrogen, a methyl, ethyl, n-propyl or an isopropyl group, preferably of Formaldehyde, acetaldehyde and / or n-butyraldehyde, especially n-butyraldehyde, have proven particularly useful.

The amounts of compound (A2) can in principle be chosen arbitrarily in the context of the present invention. Advantageously, between 0.1 and 300 parts by weight, preferably between 25 and 150 parts by weight, advantageously between 40 and 99 parts by weight, in particular between 50 and 99 parts by weight, of compound (A2) are obtained in each case per 100 parts by weight of polymer (AI). According to a particularly preferred embodiment of the present invention, the polyvinyl acetal can be obtained by a process in which at least one polymer (AI) with at least one compound (A2) of the formula (4) and at least one monosaccharide, at least one oligosaccharide, at least one polysaccharide or a mixture of at least two of these components, wherein the monosaccharide, the oligosaccharide, the polysaccharide or the mixture, based in each case on its or its total weight, contains at least 20% by weight of glucose and / or glucose units. These polyvinyl acetals are particularly suitable as binders, in particular for the production of printing ink and lacquer formulations, since they have a significantly lower solution viscosity compared to the prior art, in particular in comparison with the corresponding homoacetals, and a significantly improved addition even without the viscosity-increasing additives Viscosity stability (constant low viscosity level) and an increased pigment binding capacity. Printing ink and lacquer formulations which contain such polyvinyl acetals as binders continue to show a higher gloss than conventional formulations. Furthermore, such polyvinyl acetals have improved substrate adhesion, particularly on glass surfaces.

The terms monosaccharides, oligosaccharides and polysaccharides are well known from the specialist literature. The specialist can find valuable information in particular in the textbook H. Beyer Textbook of Organic Chemistry Beyer, Walter - 22nd revised and updated edition; by W. Walter; Stuttgart; Hirzel 1991 - Chapter 4 Carbohydrates pp. 425 - 468, to the disclosure of which reference is hereby expressly made.

For the purposes of the present invention, monosaccharides refer to simple, preferably reducing, sugars which preferably satisfy the empirical formula C _n H _2n O _n , n preferably being an integer in the range from 3 to 6, suitably in the range from 4 to 6, preferably 5 or 6, in particular 6. They preferably have an unbranched carbon chain. Farther the monosaccharides also include the numerous natural sugars in which hydrogen and oxygen do not occur in the ratio of water.

According to the invention, the term “monosaccharides” encompasses both aldehyde sugar, the so-called aldoses, and keto sugar, the so-called ketoses, aldoses being used with very particular preference according to the invention.

In principle, the monosaccharides can have both the D configuration and the L configuration. Nevertheless, D-series monosaccharides have proven particularly useful for the purposes of the present invention.

According to the invention particularly suitable monosaccharides include u. a. the following aldoses:

D-glyceraldehyde, L-glyceraldehyde, D-erythrose, L-erythrose, D-threose, L-threose, D-ribose, L-ribose, D-arabinose, L-arabinose, D-xylose, L-xylose, D- Lyxose, L-Lyxose, D-Allose, L-Allose, D-Altrose, L- Altrose, D-Glucose, L-Glucose, D-Mannose, L-Mannose, D-Gulose, L-Gulose, D-Idose, L-Idose, D-Galactose, L-Galactose, D-Talose and L-Talose as well as the following hexoses:

1,3-dihydroxyacetone, D-erythrulose, L-erythrulose, D-ribulose, L-ribulose, D-xylulose, L-xylulose, D-psicose, L-psicose, D-fructose, L-fructose, D-sorbose, L-Sorbose, D-Tagatose and L-Tagatose.

The use of D-glucose and or L-glucose has proven to be particularly favorable.

For the purposes of the present invention, oligosaccharides refer to compounds which can be obtained by acetal-like linking of 2 to 6 monosaccharides, preferably the compounds mentioned above. They therefore include disaccharides, trisaccharides, tetrasaccharides, pentasaccharides and hexasaccharides. The individual monosaccharides can be linked to one another both via the α form and via the β form. Oligosaccharides which are particularly suitable according to the invention include the following disaccharides:

Cane sugar (sucrose, ß-D-fructofüranosyl-α-D-glucopyranoside),

Milk sugar (lactose, 4-O- (-D-galactopyranosyl) -D-glucopyranose and / or 4-

O- (beta-D-galactopyranosyl) -D-glucopyranose),

Allolactose (6-O- (α-D-galactopyranosyl) -D-glucopyranose and / or 6-O- (ß-D-

Galactopyranosyl) -D-glucopyranose),

Malt sugar (maltose, 4-O- (α-D-glucopyranosyl) -D-glucopyranose and / or 4-

O- (beta-D-glucopyranosyl) -D-glucopyranose),

Trehalose (α-D-glucopyranosyl-α-D-glucopyranoside),

Cellobiose (4-O- (ß-D-glucopyranosyl) -D-glucopyranose),

Gentiobiose (6-O- (ß-D-glucopyranosyl) -D-glucopyranose) and

Melibiose (6-O- (α-D-galactopyranosyl) -D-glucopyranose) and the trisaccharides raffinose (6-O- (α-D-galactopyranosyl) -o: -D-glucopyranosyl-β-D-fructofuranoside), maltotriose (preferably 4-O- (α-D-

Glucopyranosyl) - 4-O- (-D-glucopyranosyl) -D-glucopyranose and / or 4-O- (ß-

D-glucopyranosyl) -4-O- (beta-D-glucopyranosyl) -D-glucopyranose).

According to a very particularly preferred embodiment of the present invention, disaccharides, in particular maltose, sucrose and / or lactose, are used.

For the purposes of the present invention, polysaccharides refer to compounds which can be obtained by acetal-like linking of more than 6 monosaccharides, preferably the compounds mentioned above. The individual monosaccharides can be linked to one another both via the α form and via the β form.

The polysaccharides which are particularly suitable according to the invention include starch (amylum), amylose, amylopectin and cellulose ((1-4) -β-D-glucopyranane). Starch is the assimilation product of the green plant cells and consists essentially of approx. 20% by weight of amylose ((1-4) -α-D-glucopyranan; 100 to 1400 glucose units within a chain) and approx. 80% by weight. % Amylopectin, which, like amylose, consists of D-glucose units, but which are arranged in bush-like, shorter chains, each containing 20 to 25 glucose units. The linkage within the amylopectin chain is - (1, 4) -glucosidic, however, at the branching sites α- (1, 6) - glucosidic. Its relative molecular weight is specified as 200,000 g / mol to 1 000 000 g / mol or higher.

Cellulose is the main constituent of the plant cell walls and is the most common carbohydrate. Depending on its origin, it usually has a molecular weight greater than 200,000 g / mol. Within the scope of this embodiment, mixtures of at least two of the components mentioned, in particular mixtures of monosaccharides and oligosaccharides, monosaccharides and polysaccharides, oligosaccharides and polysaccharides or of monosaccharides, oligosaccharides and polysaccharides, can also be used.

The monosaccharide, the oligosaccharide, the polysaccharide or the mixture preferably contains, based in each case on its or its total weight, at least 20.0% by weight, preferably at least 50.0% by weight, suitably at least 60.0% by weight. %, preferably at least 70.0% by weight, particularly preferably at least 80.0% by weight, in particular at least 90.0% by weight, of glucose and / or glucose units. The type of linkage of the glucose units is in principle irrelevant in this connection, it can be done both via the α-form and via the β-form, although an α-glucosidic linkage has proven particularly useful according to the invention.

In the context of a very particularly preferred embodiment of the present invention, a starch that is at least partially hydrolyzed, preferably by acid catalysis, is used. Based on their total weight, this preferably more than 70.0% by weight, suitably more than 80.0% by weight, preferably more than 90.0% by weight, in particular between 91.0 and 98.0% by weight, of glucose.

The amounts of monosaccharide, oligosaccharide and / or polysaccharide can in principle be chosen as desired. Expediently between 0.001 and 300 parts by weight, preferably between 0.01 and 150 parts by weight, in particular between 0.1 and 99 parts by weight, monosaccharide, oligosaccharide and / or polysaccharide, in each case based on 100 parts by weight. Parts of polymer (AI) used.

The structure of the polyvinyl acetals according to this embodiment has not yet been completely clarified. Nevertheless, the current results indicate that the monosaccharide, oligosaccharide and / or polysaccharide is covalently bound to the polymer, since - unlike with conventional blends - it no longer emerges from the polymer, for example by means of extraction (e.g. by Soxhlet Extraction), isolates. However, it goes without saying that the teaching of the present invention is not limited to this interpretation.

According to a further embodiment of the present invention, the polyvinyl acetal can be obtained by a process in which a mixture of

1.) 50.0 to 99.99 parts by weight of at least one polymer (AI) and

2.) reacting 0.01 to 50.0 parts by weight of at least one hydroxy compound (A3) with at least one compound (A2) of the formula (4). The sum of the parts by weight of polymer (AI) and hydroxy compound (A3) preferably gives 100 parts by weight.

Such polyvinyl acetals have properties comparable to conventional "plasticized" polyvinyl acetals, but retain them for a longer period of time. They are particularly suitable for applications at which the plasticizer normally exudes over time, since according to this embodiment a change in the property profile by separation, concentration, migration and / or exudation of components is avoided even after a long period of time, such as for example a year.

The hydroxy compound (A3) satisfies the formula (5)

The radical R ⁹ denotes hydrogen or an alkyl radical with 1 to 6 carbon atoms, preferably a methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n- Pentyl or an n-hexyl group, especially a methyl group. According to a very particularly preferred embodiment of the present invention, the radical R ^{9 represents} hydrogen.

The R ⁹ radicals can each be selected independently of one another, ie each repeating unit -CHR ⁹ -CH ₂ -O- can have a different R ⁹ radical. Consequently, the above definition of the hydroxy compound (A3) encompasses both polyethylene glycol (monoether) and polypropylene glycol (monoether) and polyethylene glycol-co-propylene glycol (monoether). The latter can have both a statistical and a block-like structure.

The radical R ¹⁰ denotes hydrogen or an alkyl radical with 1 to 10 carbon atoms, preferably a methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n- Pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl or an n-decyl group, especially a methyl group. According to a very particularly preferred embodiment of the present invention, the radical R ^{10 represents} hydrogen.

n is a number greater than or equal to 2, preferably a number in the range from 2 to 1000, advantageously in the range from 3 to 300, advantageously in the range from 3 and 25, particularly preferably in the range from 3 to 10, in particular in the range from 4 to 6. Furthermore, particularly favorable results can be achieved if n is a number in the range from 10 to 20, in particular in the range from 12 to 15.

The proportions of the starting compounds (AI), (A2) and (A3) are selected according to the invention in such a way that 0.0005 to 0.5 mol are used per mole of hydroxyl groups which contain the polymer (AI) and the hydroxy compound (A3) in total of connection (A2).

In addition, the compounds (A2) and (A3) are preferably used in a compound (A2) / compound (A3) ratio of greater than or equal to one.

The structure of these polyvinyl acetals has not yet been fully clarified. Nevertheless, the current results indicate that the hydroxy compound (A3) is covalently bound to the polymer, because - in contrast to conventional plasticizers - it no longer emerges from the polymer, for example by means of an extraction (e.g. by Soxhlet extraction) , insulates. However, it goes without saying that the teaching of the present invention is not limited to this interpretation.

The property profile of the polyvinyl acetals according to this embodiment differs markedly both from conventional polyvinyl acetals which contain no plasticizer and from those polyvinyl acetals which have been plasticized by adding plasticizer at the same degree of conversion (degree of acetalization). Compared to conventional polyvinyl acetals, which do not contain any plasticizer, the polyvinyl acetals according to this embodiment have, for example, a lower glass transition temperature, an increased ability to change shape, a lower entropy elasticity, increased elastic properties, a lower hardness and usually an increased adhesion with the same degree of acetalization. Compared to the polyvinyl acetals, which were plasticized with the same degree of conversion (degree of acetalization) by adding plasticizers, they are characterized in particular by an improved long-term stability of their properties, especially in the case of the present polyvinyl acetals there is a change in the property profile by separation, concentration, migration and / or Sweating of components due to atmospheric influences is not observed even after a long period of time, such as a year. In this context, atmospheric influences are understood to mean all the factors that can occur when using the polyvinyl acetals, especially outdoors, such as, for example, solar radiation, oxygen, ozone, other gaseous components of the air, temperature, air humidity, precipitation, dust deposits, etc. ,

These improved long-term properties can be compared in particular when comparing the glass transition temperature (preferably measured using DSC, Mettler Toledo Star System, heating rate 1 OK / min, 2nd heating), the entropy elasticity module (preferably measured in accordance with DIN 7724 (February 1972)), the tear strength (preferably measured according to DIN 53455), the elongation at break (preferably measured according to DIN 53455), the water absorption and / or the surface tension of the polyvinyl acetals according to this embodiment can be observed with conventionally externally plasticized polyvinyl acetals.

The reaction of the starting compounds (AI), (A2) and optionally the hydroxy compound (A3) and / or the monosaccharide, oligosaccharide, polysaccharide or a mixture of at least two of these components is preferably carried out in at least one solvent. A particularly useful solvent in this connection is water.

The reaction is further conveniently carried out in the presence of acidic catalysts. Suitable acids include both organic acids, such as acetic acid, and mineral acids, such as hydrochloric acid, sulfuric acid and / or nitric acid, the use of hydrochloric acid, Sulfuric acid and / or nitric acid has proven particularly useful in technology. The reaction is preferably carried out in such a way that a mixture of components (AI) and (A2), optionally the hydroxy compound (A3) and / or the monosaccharide, oligosaccharide and / or polysaccharide or a mixture thereof, is initially introduced in aqueous solution and then the acid catalyst added dropwise. According to a further preferred embodiment of the present invention, it has also proven to be advantageous to present a mixture of components (AI) and (A2) in aqueous solution, to stir the acid catalyst into this solution and then to add the monosaccharide, oligosaccharide and / or polysaccharide or a mixture of them. According to a third preferred embodiment of the present invention, it has also proven to be advantageous to present a mixture of components (AI) and (A2) in aqueous solution, to stir the acid catalyst into this solution and then to carry out the reaction by adding compound (A3 ) to continue.

The reaction temperature can be varied over a wide range, but often the temperature is in the range from -20.0 ° C to 100.0 ° C, preferably in the range from 0.0 ° C to 80.0 ° C. The same applies to the pressure at which the implementation is carried out. The reaction can take place both under negative pressure and under positive pressure. However, it is preferably carried out at normal pressure.

Alternative methods of producing the polymers are obvious to the person skilled in the art. For example, instead of the compound (A2), it is possible to use compounds which release compounds (A2) under the chosen reaction conditions. These include cyclic trimers of aldehydes and acetals of aldehydes or ketones. Furthermore, in the context of the first preferred embodiment it is of course also possible to partially acetalize the polymer (AI) first by reaction with a corresponding amount of monosaccharide, oligosaccharide and / or polysaccharide or a mixture thereof and then the resulting polymer with compound (A2) implement. Furthermore, in the context of the second preferred embodiment, there is also the possibility of first partially acetalizing the polymer (AI) by reaction with an appropriate amount of compound (A2), then adding the hydroxy compound (A3) and the resulting mixture with a further amount of compound Implement (A2).

According to a preferred embodiment of the present invention, the polyvinyl acetal is cross-linked. The crosslinking can be carried out in a manner known per se, for example by reacting remaining hydroxyl groups in the polyvinyl acetal with di- or polyaldehydes. However, it is particularly advantageous to crosslink the polyvinyl acetal by reaction and intermolecular esterification of remaining hydroxyl groups in the polymer with an anacetalized aldehyde carboxylic acid, in particular glyoxylic acid.

In the context of a further preferred embodiment of the present invention, the polyvinyl acetal is not crosslinked and preferably has a weight average molecular weight of less than 1 000 000 g / mol, advantageously less than 500 000 g / mol, in particular less than 200 000 g / mol. The weight average molecular weight can be determined in a manner known per se, for example by means of static light scattering. For the purposes of the present invention, gel permeation chromatography, advantageously using a polyvinyl acetal calibration, has also proven particularly useful.

In the context of the present invention, the mixture further contains oxalic acid, i.e. H. a compound of the formula

and at least one antioxidant. The weight ratio of oxalic acid to antioxidant is advantageously in the range from 1:20 to 20: 1, expediently in the range from 1:10 to 10: 1, particularly preferably in the range from 1: 5 to 5: 1.

Antioxidants, sometimes also called oxidation inhibitors, in the context of the present invention, preferably organic, denote compounds which are undesirable due to the action of oxygen and the like. a. Oxidative processes inhibit and / or prevent changes in the polyvinyl acetal. Such connections are well known from the prior art and z. B. in plastics and rubbers (especially for protection against aging), fats (especially for protection against rancidity), oils, cattle feed, automotive gasoline and jet fuels (especially for protection against resinification), transformer and turbine oil (especially for protection against sludge formation), Flavorings (in particular to protect against the formation of undesirable aroma components) and paints (in particular to protect against skin formation).

The effect of the antioxidants is mostly that they act as a radical scavenger for the free radicals that occur during auto-oxidation. For further details, reference is made to the current specialist literature, in particular to the Römpp Lexicon Chemistry; Editor: J. Falbe, M. Regitz; Stuttgart, New York; 10th edition (1996); Keyword "antioxidants" and the literature references cited here.

Antioxidants particularly suitable for the purposes of the present invention include tocopherol, tert-butylmetoxyphenol (BHA), butylhydroxytoluene (BHT), octyl gallate, dodecyl gallate, ascorbic acid, lactic acid, citric acid, tartaric acid, optionally substituted phenols, optionally substituted hydroclones, optionally substituted Substituted quinones, optionally substituted pyrocatechols, optionally substituted aromatic amines, optionally substituted metal complexes of an aromatic amine, optionally substituted triazines, organic sulfides, organic polysulfides, organic dithiocarbamates, organic phosphites and organic phosphonates. Mixtures which are particularly preferred according to the invention have substituted phenols as antioxidants. These preferably satisfy the formula (6)

where the R ¹¹ radicals, each independently of one another, are hydrogen, a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso- Butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, which advantageously has 1 to 4 carbon atoms, an optionally substituted cycloalkyl radical, preferably having 4 to 8 carbon atoms, in particular a cyclohexyl radical, an optionally substituted aryl radical, preferably having 6 to 18 carbon atoms, or a halogen, preferably fluorine, chlorine or bromine, and where R ^{12 is} a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular for one Methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or for an n -Octyl radical, which particularly preferably has 1 to 4 carbon atoms, for an optionally substituted cycloalkyl radical, preferably possibly with 4 to 8 carbon atoms, in particular for a cyclohexyl radical, or for an optionally substituted aryl radical, preferably with 6 to 18 carbon atoms.

Furthermore, compounds of the formula (7) have also proven particularly useful for the purposes of the present invention

where the R ¹³ radicals, each independently of one another, are hydrogen, a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso- Butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, which particularly preferably has 1 to 4 carbon atoms, an optionally substituted cycloalkyl radical, preferably with 4 to 8 carbon atoms , in particular a cyclohexyl radical, an optionally substituted aryl radical, preferably having 6 to 18 carbon atoms, a halogen, preferably fluorine, chlorine or bromine or a radical of the formula (8),

in which R ^{14 represents} a linear or branched alkyl radical having 1 to 6 carbon atoms, preferably a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, , n-pentyl or n-hexyl radical, in particular an ethyl radical.

Compounds which are particularly favorable in this connection satisfy the formula (9)

In addition, particularly favorable results can also be achieved using compounds of the formula (10)

where o is an integer in the range from 1 to 4 and p is 1 or 2, preferably 2, the radicals R ¹⁵ , in each case independently of one another, being hydrogen, a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular one Methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n- Octyl radical, which particularly preferably has 1 to 4 carbon atoms or is an optionally substituted cycloalkyl radical, preferably having 4 to 8 carbon atoms, in particular a cyclohexyl radical, where R ^{16 is} hydrogen or a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular one Methyl, ethyl, n-propyl, iso-propyl, n- Butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, in particular a methyl radical, and where R ¹⁷ denotes a monovalent alkyl group or divalent Alkylene group, preferably a linear, α, ω-double-bonded alkylene group, preferably having 1 to 8 carbon atoms, in particular for a methyl, methylene, ethyl, 1,2-ethylene, n-propyl, 1,3-n- Propylene, iso-propyl, n-butyl, iso-butyl, ter-butyl, 1,4-butylene, n-pentyl, 1,5-pentylene, n-hexyl, 1.6 - Hexylene, n-heptyl, 1,7-heptylene, n-octyl or a 1,8-octylene group, which particularly preferably has 1 to 4, very particularly preferably 2, carbon atoms.

A particularly preferred compound of the formula (10) is bis- [3,3-bis- (4'-hydroxy-3'-tert-butylphenyl) butanoic acid] glycol ester.

In the context of a particularly preferred embodiment of the present invention, the antioxidant is an optionally substituted quinone, which advantageously has the formula (11)

wherein the radicals R, each independently of one another, hydrogen, a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl -, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, which particularly preferably comprises 1 to 4 carbon atoms, an optionally substituted cycloalkyl radical, preferably having 4 to 8 carbon atoms, in particular a cyclohexyl radical, an optionally substituted aryl radical, preferably having 6 to 18 carbon atoms, or are a halogen, preferably fluorine, chlorine or bromine.

Furthermore, optionally substituted triazines, in particular those of the formula (12), have also proven particularly useful for the purposes of the present invention.

wherein the R ¹⁹ radicals are an optionally substituted hydroxyphenyl radical, preferably a radical of the formula (12a), (12b) or (12c)

In this context, R ²⁰ stands for a bond or for a, preferably linear, α, ω-double-bonded alkylene group, preferably with 1 to 8 carbon atoms, in particular for a methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1,7-heptylene or a 1,8- Octylene group, which particularly preferably has 1 to 4, very particularly preferably 2, carbon atoms and characterizes the radicals R ²¹ , in each case independently of one another, hydrogen, or a linear or branched alkyl radical, preferably having 1 to 8 carbon atoms, in particular a methyl or ethyl -, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, which is particularly preferred Has 1 to 4, very particularly 1 or 2, carbon atoms.

Furthermore, according to the invention, benzofuranones have also proven to be very particularly advantageous as an antioxidant. These preferably satisfy the formula (13)

The radicals R ²² , R ²³ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ denote, independently of one another, hydrogen, a hydroxyl group, a linear or branched alkyl group, preferably having 1 to 18 carbon atoms, in particular a methyl -, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl group which particularly preferably comprises 1 to 4 carbon atoms, an unsubstituted or a mono-, di- or tri-alkyl-substituted phenyl group, the alkyl group preferably containing 1 to 4 carbon atoms, a phenylalkyl group which preferably comprises 7 to 9 carbon atoms, a cycloalkyl group with preferably 5 to 12 carbon atoms, in particular a cyclohexyl group, which can be unsubstituted or mono-, di- or tri-alkyl-substituted, the alkyl radical (s) preferably containing 1 to 4 carbon atoms, or an alkoxy group with preferably 1 to 18 carbon atoms, Especially a methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptoxy or one n-Oktoxygruppe.

The radical R ²⁴ is hydrogen, a hydroxyl group, a linear or branched alkyl group, preferably having 1 to 18 carbon atoms, in particular a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, , tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl group, which particularly preferably comprises 1 to 4 carbon atoms, an unsubstituted or a mono-, di- or tri-alkyl-substituted phenyl group , where the alkyl group preferably contains 1 to 4 carbon atoms, a phenylalkyl group which preferably comprises 7 to 9 carbon atoms, a cycloalkyl group with preferably 5 to 12 carbon atoms, in particular a cyclohexyl group which may be unsubstituted or mono-, di- or tri-alkyl-substituted, the alkyl radical (s) preferably containing 1 to 4 carbon atoms, an alkoxy group having preferably 1 to 18 carbon atoms, in particular a methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, iso-butoxy, tert .- butoxy, n-pentoxy, n-hexoxy, n-heptoxy or an n-octoxy group, or a radical of the formula (14)

The radicals R ²² , R ²³ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ have the abovementioned meaning, preferably at least two of the radicals R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ^{29 being} hydrogen ,

The radicals R ³⁰ and R ³¹ each, independently of one another, represent hydrogen or a linear or branched alkyl group, preferably having 1 to 18 carbon atoms, in particular a methyl, ethyl, n-propyl, iso-propyl, n-butyl -, Iso-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl group, which particularly preferably comprises 1 to 4 carbon atoms. Appropriately, both radicals R ³⁰ and R ^{31 denote} a methyl group.

Compounds of the formula (13) which are very particularly suitable according to the invention have hydrogen as the radical R or hydrogen as the radical R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ²⁹ or hydrogen as the radical R ²² , R ²³ and R ²⁴ an alkyl group with preferably 1 to 18 carbon atoms, in particular a tert-butyl group, or an unsubstituted or mono-, di- or trisubstituted phenyl group, in the latter case the alkyl group preferably containing 1 to 4 carbon atoms.

In a very particularly preferred embodiment of the present invention, 1,4-dihydroxybenzene, 4-methoxyphenol, 2,5-dichloro-3,6- dihydroxy-l, 4-benzoquinone, l, 3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2,6-di-tert. butyl-4-methylphenol, 2,4-dimethyl-6-tert. butylphenol, 2,2-bis [3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl-1-oxopropoxymethyl)] l, 3-propanediyl ester, 2,2'-thiodiethylbis- [3- (3.5 -di-tert-butyl-4-hydroxyphenyl)] propionate, octadecyl-3 - (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,5-bis (l, l-dimethylethyl-2,2 -Methylenbis- (4-methyl- 6-tert.butyl) phenol, tris- (4-tert.butyl-3-hyα oxy-2,6-dimethylbenzyl) -s-triazine-2,4,6- (, 3H , 5H) rrion, tris (3,5-ditert.buryl-4-hychoxy) -s-triazine-2,4,6- (1H, 3H, 5H) trione and / or tert-butyl-3,5-dihydroxybenzene as Antioxidant used.

Based on the total weight of the mixture according to the invention, the proportion of the antioxidants individually or as a mixture is 0.001 to 2.0% by weight, the concentration of the inhibitors preferably being selected so that the color number according to DEM 55945 is not impaired.

According to a particularly preferred embodiment of the present invention, the antioxidant is used in combination with synergistic nitrogen-containing, sulfur-containing or phosphorus-containing costabilizers, preferably of types a) to d) or in combination with mixtures of costabilizers of types a) to d). a) nitrogen-containing compounds of the formula (15)

wherein the radicals R, in each case independently of one another, are a linear or branched alkyl radical, preferably having 1 to 4 carbon atoms, such as a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or a tert-butyl radical, in particular a methyl radical, or an optionally substituted cycloalkyl radical, preferably having 4 to 8 carbon atoms, in particular a cyclohexyl radical, where R ^{33 is} hydrogen, a linear or branched alkyl radical, preferably having 1 to 18 carbon atoms, in particular for a methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert. -Butyl, n-pentyl, n-hexyl, n-heptyl or an n-octyl radical, which particularly preferably has 1 to 8, very particularly preferably 1 to 4, carbon atoms, an optionally substituted cycloalkyl radical, preferably with 4 up to 8 carbon atoms, in particular for a cyclohexyl radical, a linear or branched hydroxylalkyl radical, preferably with 1 to 18, preferably 1 to 8, in particular 1 to 4, carbon atoms, or a linear or branched alkoxy radical, preferably with 1 to 18, preferably 1 to 8 , in particular 1 to 4, carbon atoms, particularly preferably hydrogen, and the radicals R ³⁴ , each independently of one another, characterize a linear or branched alkyl radical which preferably has one or more, optionally different, heteroatoms e nitrogen and / or oxygen, which may be the same or different and may contain epoxy groups, or where the radicals R ³⁴ together with the carbon atom of the piperidine ring form a monocyclic or polycyclic radical having up to 60 carbon atoms, which may be branched and a or can contain several, optionally different heteroatoms, preferably nitrogen and / or oxygen, and epoxy groups, furthermore the use of polymeric or copolymeric forms of compounds of the formula (15) is also particularly favorable for the purposes of the present invention;

nitrogen-containing compounds from the group of the aliphatic

Carboxylic acid hydrazides or dicarboxylic acid dihydrazides, preferably with 2 up to 12 carbon atoms, especially adipic acid dihydrazide, particularly preferably acetic acid hydrazide;

c) Sulfur-containing compounds from the group of dialkyl sulfides and disulfides, the alkyl radicals preferably having 4 to 18, in particular 8 to 12, carbon atoms, thiotin compounds of the formula R _x Sn (-S-CH2-COOR) _y , where x + y = 4 , x, y = 1 to 3, preferably x, y = 2, and R represents a linear or branched alkyl radical, preferably having 1 to 18 carbon atoms, advantageously 8 to 12 carbon atoms, in particular an octyl radical, dialkyl thiodipropionates, the Alkyl radicals preferably have 1 to 18, advantageously 8 to 14 carbon atoms, particularly preferably dilauryl thiodipropionate; d) phosphorus-containing compounds from the group of hydrolysis-resistant phosphites, preferably alkylaryl phosphites, in particular tris (2,4-ditert.-butylphenyl) phosphite.

The compounds mentioned above as costabilizer types a) to d) surprisingly show a synergistic antioxidative and thermostabilizing activity in the context of the present invention in that they can bring about a further reduction in the oxidatively and thermally caused discoloration of the film, while such activity cannot be observed in their individual use , The light-stabilizing effect of the costabilizers of the formula (15) obviously remains when they are synergistically combined with the antioxidants in polyvinyl acetals, in particular in polyvinyl butyral films, and can additionally contribute to the stabilization of the light of the polyvinyl acetal. Particularly good synergistic effects can be achieved by combining several different, preferably up to 4, costabilizers of types a) to d). Among the nitrogenous costabilizers of type a) of the formula (15) specified above, which are piperidine derivatives according to the structure, the known light stabilizers of the "HALS" type (= hindered amine light stabilization) are preferably used. It was surprisingly found here that their synergistic costabilizing and yellowing-inhibiting activity increases with increasing molecular weight of the HALS component, as a result of which polyvinyl acetals, in particular plasticized PVB flat foals, can be obtained with an even more pronounced tendency to yellowing, so that the higher molecular weight HALS compounds of type a ) are particularly preferred costabilizers. Polymeric and copolymeric forms of compounds of the formula (15) are also particularly preferred, since these, inter alia, cannot migrate from the PVB either. The polymeric and copolymeric forms prepared from compounds of the formula (15) containing epoxide groups are particularly preferred. The following compounds are particularly preferably used as costabilizers of the formula (15):

Bis (2,2,6,6-tetramethylpiperidyl) sebacate, glutarate and succinate, bis (1,2,2,6,6-pentamethylpiperidyl) sebacate, glutarate and succinate, 4-stearyloxy and 4-stearoyloxy-2,2,6,6-tetramethyl-piperidine, 4-stearyloxy and 4-stearoyloxy-l, 2,2,6,6-pentamethyl-piperidine, 2,2,6,6-tetramethylpiperidyl behenate, 1,2,2,6,6-Pentamethylpiperidylbehenat,

2,2,4,4-tetramethyl-7-oxa-3, 20-diaza-dispiro [5.1.11.2] heneicosan-21-one, 2,2,3,4,4-penta-methyl-7- oxa-3,20-diaza-dispiro [5.1.11.2] heneicosan-21-one, 2,2,4,4-tetramethyl-3-acetyl-7-oxa-3,20-diaza-dispiro [5.1 .11.2] -heneicosan-21 - on,

2,2,4,4-teframethyl-7-oxa-3,20-ώaza-20- (ß-lauryloxycarbonylethyl) -21-oxo-dispiro- [5.1.11.2] heneicosane,

2,2,3,4,4-pentamethyl-7-oxa-3,20-diaza-20- (ß-lauryloxycarbonylethyl) -21-oxo-dispiro- [5.1.11.2] heneicosane,

2,2,4,4-tetramethyl-3-acetyl-7-oxa-3,20-diaza-20- (ß-lauryloxycarbonylethyl) -21-oxo-dispiro [5.1.11.2] heneicosane, l, r, ^3.3, ^5.5, -Ηexahydro-2,2 ', 4,4', 6,6 ', - ^{hexaaza-2,2,,} 6,6'-Bismethano-7,8 dioxo-

4,4'-bis- (l, 2,2,6,6-pentamethyl-4-piperidyl) biphenyl,

N, ^N, N ', ^N' tetrakis- {2,4-bis- [N- (2,2,6,6-tetramethyl-4-piρeridyl) butylamino] - l, 3,5-triazine -6-yl} -4,7diazadecan-l, 10-diamine,

N, N ', N ", N" ^, -Tetrakis {2,4-bis- [N- (1,2,6,6-pentamethyl-4-piperidyl) butylamino] - 1,3,5 -triazin-6-yl} -4,7-diazadecan- 1, 10-diamine,

N, N ', N ", N" ^, -Tetrakis- {2,4-bis- [N- (2,2,6,6-tetramethyl-4-piρeridyl) methoxypropylamino] - 1, 3, 5 -triazine -6-yl} -4,7-diazadecan- 1, 10-diamine,

N, ^N, N ', ^N' tetrakis- {2,4-bis [N- (l, 2,2,6,6-pentamethyl-4-piperidyl) - methoxypropylarmno] -l, 3-5 triazin-6-yl} -4,7-diazadecane-l, 10-diamine,

Bis- (1,2,6,6-pentamethyl-piperidyl) -n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate,

Tris- (2,2,6,6-tetiamethyl-4-piperidyl) nitrilotriacetate,

Tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1, 2,3,4-butanetetracarboxylic acid,

1, 1 '- (1, 2-ethanediyl) bis (3,3,5,5-tetramethyl-piperazinone); also poly-N, N ¹ -bis- (2,2,6,6-tetramethyl-4-piperidyl) -1,8-diazadecylene, condensation products from l- (2-hydroxyethyl) -2,2,6,6- tetramethyl-4-hydroxypiperidine and succinic acid,

Condensation products from N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 4-tert-ol tylamino-2,6-dichloro-l, 3,5-s-triazine Condensation products of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 4-monopholino-2,6-dichloro-l, 3,5-triazine, and polymerized 2, 2,4,4-tetramethyl-7-oxa-3,20-diaza- (2,3-epoxypropyl) - dispiro [5.1.11.2.] - heneicosan-21-one, obtained from the monomeric compound of the formula

the polymerization takes place via the epoxy propyl group. This polymeric product is a particularly preferred cost-base based on a formula (15) compound of type a). The molecular weight of the polymer is not critical and can vary within a wide range with the premise that the product must always be completely and clearly soluble in the polyvinyl acetal.

When the costabilizers of types a) to d) are also used, the amount of antioxidant used is preferably 0.05 to 0.6% by weight, in particular 0.07 to 0.4% by weight, particularly preferably 0.1 to 0, 3 wt .-%, and the amount of the costabilizer or the costabilizer mixture preferably 0.01 to 0.5 wt .-%, in particular 0.1 to 0.4 wt .-%, the total amount of antioxidant and costabilizer (s ) is preferably <0.8% by weight, in particular 0.2 to 0.4% by weight, in each case based on the total weight of the mixture. The weight ratio of antioxidant to the costabilizer or costabilizer mixture is preferably 90:10 to 20:80.

In the context of the present invention, it may be expedient that the mixture - depending on the application - contains further additives. Additives which are particularly useful in this context include further polymer resins, plasticizers, pigments, fillers, light stabilizers, preferably UV stabilizers, in particular benzotriazole derivatives, adhesion improvers, non-stick agents, theological auxiliaries, additives and substances which influence the pH, and the chemical reactions between the polyvinyl acetal catalyze themselves or with the other polymer resins, if any, or between the polymer resins, if any, or cause them themselves. Additives that are particularly advantageous according to the invention are fiber-strengthening materials, in particular short glass fibers, long glass fibers, aramid fibers and / or carbon fibers.

The proportion of additives depends primarily on the intended application and thus the required property profile. Very small amounts, such as, for example, only 0.1% by weight, based on the Total weight of the mixture, as well as very large amounts may be required. However, it has proven to be particularly favorable that the total proportion of additives, based in each case on the total weight of the mixture, is at most 50.0% by weight, preferably at most 40.0, suitably at most 35.0% by weight, preferably at most 30.0% by weight, in particular less than 25.0% by weight.

Methods for producing the mixture according to the invention are immediately obvious to the person skilled in the art. It is preferably carried out by mixing components A.) to C), which can be carried out both stepwise and simultaneously. Furthermore, the oxalic acid and or the antioxidant (s) can be added both during the preparation of the polyvinyl acetal, i.e. before or during the acetalization of the starting polyvinyl alcohol, and during further processing, in particular before the extrusion, of the polyvinyl acetal, in the latter case preferably by Oxalic acid and / or the antioxidants are first dissolved or dispersed in a plasticizer and the polyvinyl acetal is plasticized with the plasticizer solution.

The antioxidant or antioxidants are preferably added in the course of the preparation of the polyvinyl acetal by preferably dissolving the stabilizers in the aqueous polyvinyl alcohol solution to be acetalized in the aldehyde or, if appropriate, in a water-dilutable solvent such as methanol or methanol / acetone 1: 1 added dropwise, as a result of which the entire amount of stabilizer is well distributed in the polyvinyl acetal formed.

The oxalic acid, on the other hand, is preferably added, as described above, appropriately dispersed in the plasticizer before the preferably thermoplastic processing of the polyvinyl acetal.

According to a first very particularly preferred embodiment of the present invention, components A.) to C.) and, if appropriate, further additives are kneaded together in the respective amounts used mixed, which is preferably carried out at a temperature below 230 ° C, in particular in the range from 100 to below 220 ° C.

According to a second very particularly preferred embodiment of the present invention, components A.) to C.) and, if appropriate, further additives are mixed with one another in the respective amounts used by thermoplastic processing, preferably by means of an extruder. The thermoplastic processing is advantageously carried out at a temperature in the range from 100 to 300 ° C.

Possible areas of use for the mixture according to the invention are obvious to the person skilled in the art. It is particularly suitable for all applications which are drawn for polyvinyl acetals, in particular for polyvinyl formals and / or polyvinyl butyrals. Due to the characteristic property profile, however, it is particularly advantageous in applications in which the highest possible thermal stability and / or color stability is desired.

Areas of application which are particularly preferred according to the invention include the use of the mixture according to the invention as a raw material for the production of laminated glass films, as a binder, in particular as a binder for printing inks and coatings, as a, preferably temporary, binder for ceramics, as a binder for thermally developable, photosensitive layers and as adhesives and again peelable coatings. It can also be used particularly advantageously for the production of fibers.

In many cases, new, expanded areas of application are also accessible; for example in the area of additives for construction chemicals (tile adhesives, mortar, cementitious masses and the like), in the area of emulsion and suspension polymerization.

A particularly preferred area of application of the mixture according to the invention in the context of the present invention is flat structures and moldings, in particular films or foils, preferably with a thickness in the Range from 0.5 μm to 2.0 mm. Depending on the desired glass transition temperature Tg, these can contain certain amounts, preferably less than 60% by weight, in particular less than 50% by weight, based on the total amount of polyvinyl acetal, of conventional plasticizers or plasticizer mixtures. A list of commercially available plasticizers, which contains information about their compatibility with polyvinyl acetals, in particular polyvinyl butyral, can be found, for example, in the publication Modem Plastics Encyclopedia 1981/1982, pp. 710 to 719. Preferred plasticizers are diesters of aliphatic diols, especially of aliphatic polyether diols or polyether polyols, with aliphatic carboxylic acids, preferably diesters of polyalkylene oxides, especially diesters of di-, tri- and tetraethylene glycol with aliphatic (C _o -Ci ^ -carboxylic acids, preferably 2-ethylbutyric acid and n-heptanoic acid, also diesters of aliphatic or aromatic (C ₂ -C ₁₈ ) dicarboxylic acids, preferably adipic, sebacic and phthalic acid, with aliphatic (C ₄ -C ₁₂ ) alcohols, preferably dihexyl adipate, phthalates, trimellitate, phosphates , Fatty acid esters, especially triethylene glycol bis (2-ethylbutyrate), aromatic carboxylic acid esters, especially dibenzoates, and / or hydroxycarboxylic acid esters, but it has proven to be particularly advantageous in the context of the present invention that the polyvinyl acetals contain no further additives.

The optionally plasticized polyvinyl acetals are preferably extruded by means of thermoplastic extrusion through slot dies to preferably 0.5 μm to 2.0 mm, in particular to 0.2 to 2 mm thick flat films. The extrusion temperature of the extrusion molding compositions is in the usual range, preferably between 140 and 250 ° C., although higher temperatures can also be reached for a short time. Flat films can also be produced by thermoplastic shaping of the polyvinyl acetal molding compositions stabilized according to the invention on a heatable three-roll mill or a calender. In addition to the stabilizers and plasticizers already mentioned above, the extrusion molding compositions may also contain other customary additives, such as, for example, small amounts of basic compounds, preferably for example 0.001 to 0.1% by weight, based on the polyvinyl acetal, alkali metal hydroxide or alkaline-reacting alkali metal salt for stabilization of polyvinyl acetal against acid hydrolysis. This alkali content is usually also referred to as the alkali titer of polyvinyl acetal. The plasticized polyacetal extrusion molding compositions can furthermore contain known anti-adhesive agents in conventional amounts, such as, for example, alkali metal salts or alkaline earth metal salts of carboxylic acids, preferably potassium or magnesium salts of formic acid or acetic acid or combinations of these salts with potassium or magnesium salts of hydroxycarboxylic acids, furthermore alkali metal or alkaline earth metal alkali metal salts or magnesium acetylacetonate and various silanes or siloxanes, such as, for example, 3- (methyltriethylene glycol) propylsilane tris methyltriethylene glycol ester. The amount of these non-stick agents used is preferably in the range from 0.001 to 0.2% by weight, based on the total weight of the mixture according to the invention.

When additional light stabilizers, preferably UV stabilizers, such as the known benzotriazole derivatives, are also used, it has surprisingly been found that the amounts of these UV stabilizers used can be considerably reduced if they are used in combination with the stabilizer system according to the invention. On the one hand, this is economically advantageous and, surprisingly, also leads to films with improved color values, i.e. lower inherent color of the foils, which is particularly important for their use in the production of glass composites.

In addition, in the case of film extrusion of plasticized polyvinyl acetals, in particular polyvinyl butyrals, it is particularly important to be able to extrude at the highest possible melt temperatures, in order to lower the melt viscosity of the plasticized extrusion composition as much as possible or to keep it as low as possible and to achieve the highest possible extruder throughputs To be able to achieve unit time without damaging the extrusion mass oxidatively and / or thermally and producing yellowing. By using the polyvinyl acetals stabilized according to the invention, these requirements can be largely met.

The films described above are particularly suitable for the production of laminated safety glasses, which is advantageously carried out in a known manner by the autoclave method, for the test glass laminates of 30 x 30 cm in an autoclave at 140 ° C, a pressure of 12 bar and a holding time of 2 hours getting produced. The significantly reduced discoloration or yellowing of the films according to the invention can be determined in a known manner using the Yellowness Index according to ASTM-D-1925.

The mixture according to the invention is also very particularly suitable for producing a polyvinyl acetal solution, in particular one

Bescln ^ htungszusammensetzung. The coating composition can be applied to a wide variety of substrates, in particular to wood, metal, plastic, glass, textiles, paper, leather and ceramic and mineral substrates. It can contain, as further constituents, in particular further polymer resins, plasticizers, pigments, fillers, stabilizers, adhesion improvers, theological aids, additives and substances which influence the pH value, the chemical reactions between the polyvinyl acetal with itself or with the other polymer resins also catalyze or enable each other between the other polymer resins.

The coating can be applied both as a powder, which is subsequently melted at elevated temperature, as a melt, and also from solution or dispersion, the coating composition being applied to the substrate to be coated and then dried, by means of coating processes known to the person skilled in the art. The excellent ones come especially in the latter two cases Binder properties of the polyvinyl acetals to bear by allowing an extremely uniform setting of the solution or the dispersion and at the same time preventing or significantly delaying the gelling composition.

According to the invention, binders denote substances which combine identical or different substances, the setting of the substances taking place by physically drying the solution or dispersion. In the case of paints and varnishes which are in the foreground in the context of a particularly preferred embodiment of the present invention, binders are defined in accordance with DIN 55945 (12/1988) and characterize the non-volatile component or components without pigment and filler, but including plasticizers, drying agents and others. non-volatile auxiliaries. The purpose of the binders is to bind the pigment particles to one another and to the substrate.

In the context of a preferred embodiment of the present invention, the coating is applied as a dispersion to the substrate to be coated. According to DIN 53900 (July 1972), the term "dispersions" stands for a disperse system consisting of several phases, one of which is continuous (dispersant) and at least one further is finely divided (dispersed phase, dispersant). In the present case, the dispersant is a solvent or mixture, which can also contain water. The dispersant can be chosen freely depending on the application. It includes, for example, colorants (pigments), especially for printing inks.

The dispersant is expediently not completely soluble in the amounts used in the dispersant. The solubility at 25 ° C. in the dispersant is preferably less than 1.0 g per 100 g of dispersant, advantageously less than 0.1 g per 100 g of dispersant. Furthermore, the dispersant is preferably a solid, ie it has a dynamic viscosity greater than 10 mPa s, advantageously greater than 100 kPas s, in particular at 25 ° C. and at normal pressure (101325 Pa).

In the context of this embodiment, the dispersion of the particles to be dispersed by the polyvinyl acetals is facilitated by lowering the interfacial tension between the two components, that is to say bringing about wetting. The wetting tendency can be derived from the determination of the contact angle that the liquids form with the solid surface: σ ₁ -γ _lj2 = σ ₂ -cos α

[σ, or σ ₂ = surface tension of the solid or liquids, Yι, _2- interfacial tension solid / liquid, α = contact angle or contact angle) (see Römpp Lexikon Chemie - Version 2.0, Stuttgart / New York: Georg Thieme Verlag 1999) - Keyword: wetting].

The composition of the dispersion can be chosen freely within the scope of the present invention, depending on the application.

In the context of a further particularly preferred embodiment of the present invention, the coating is applied as a solution to the substrate to be coated. In the context of the present invention, solutions refer to homogeneous liquid mixtures of different substances, with the tiniest part volumes of the solution still having a similar composition. They include at least one solvent, i.e. H. at least one liquid with a dynamic viscosity, in particular at 25 ° C and at normal pressure (101325 Pa), in the range of 0.1 to 10 mPa s.

In the context of this embodiment, the substance to be dissolved, in particular the polyvinyl acetal, is completely soluble, preferably in the amounts used in the solvent, in particular in alcohols, which preferably have 1 to 8 carbon atoms. The solubility is at 25 ° C in Solvent preferably greater than 0.1 g per 100 g of solvent, advantageously greater than 1.0 g per 100 g of solvent.

The composition of the solution can be chosen freely within the scope of the present invention, depending on the application. Alcohols, in particular aliphatic alcohols having 1 to 12, preferably 1 to 8, in particular 1 to 4, carbon atoms have proven particularly useful as solvents or cosolvents. Very particularly advantageous results can be achieved using methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and / or tert-butanol.

The dispersion or the solution can be prepared in a manner known per se, preferably mechanically.

Although the polyvinyl acetals described above are particularly suitable as binders, it may be appropriate in individual cases to use further co-binders, for example to improve pigment wetting or pigment dispersion or adhesion. Suitable co-binders include all known binders, preferably organic binders and other polymers

The amounts of co-binder can be chosen as desired depending on the application.

Possible areas of application of the coating compositions are immediately obvious to the person skilled in the art on the basis of the present description. They are particularly suitable for those applications which are designed for solutions and dispersions containing conventional binders.

The coating composition is advantageously used as a printing ink. Printing inks refer to liquid, pasty or powdery colorant preparations that are used in printing machines. The material to be printed in various printing processes can generally absorbent or non-absorbent, flat (for example paper, cardboard, leather, foils), cylindrical or conical (for example cans or other hollow bodies). With regard to the special conditions of printing on textiles, reference is made to the specialist literature - keyword "textile printing".

The printing inks are very finely divided mixtures, dispersions or solutions, which are composed of:

Colorants (pigments including fillers or dyes, also fluorescent in the case of fluorescent printing inks),

• Binder solutions (mostly called (printing) fimisse) and

• additives (for example drying agents, diluents, wax dispersions, catalysts or initiators for radiation drying).

The composition of the printing inks, which may be prepared using the flushing process, depends not only on the printing process (high, flat, rotogravure and screen printing), but especially on the substrate and the requirements for the print result with regard to appearance (color, transparency or opacity) , Gloss, fluorescence) and physical properties (water, grease, solvent, abrasion resistance, lamination and overpainting ability, etc.). A current point of view today - during recycling - is to be able to remove the applied printing inks if necessary (de-inking).

For further details, reference is made to the current specialist literature, in particular to the following publications, the disclosure of which is hereby expressly incorporated by reference:

• Erwin Schulz, "Flexo printing from A to Z", Polygraph Verlag, Frankfurt am Main, 1987 reference work on "Flexo printing"

"The Printing Ink Manual" Chapman & Hall detailed information on the starting materials and common formulations

• Chris Williams "Printing Ink Technology" PIRA detailed information on printing technology

In the context of a further preferred embodiment of the present invention, the mixture according to the invention is used to produce ion-conductive intermediate layers for electrochromic systems.

Claims

claims:

1. A mixture comprising, in each case based on their total weight, A.) at least 50.0% by weight of at least one polyvinyl acetal, obtainable by a process in which a polymer (AI) which, based on its total weight, a) 1 , 0 to 100.0% by weight of structural units of the formula (1)

wherein R ⁷ and R ^{8 are} each independently hydrogen, COOH, COOM, an alkyl group having 1 to 10 carbon atoms or an optionally substituted aryl group having 6 to 12 carbon atoms and where M is a metal cation or an optionally alkylated ammonium cation, B.) 0.001 to 2.0% by weight of oxalic acid and C.) 0.001 to 2.0% by weight of at least one antioxidant.

2. Mixed breed according to claim 1, characterized in that the oxalic acid and the antioxidant are present in a weight ratio in the range from 1:20 to 20: 1.

3. Mixture according to spoke 1 or 2, characterized in that the antioxidant tocopherol, tert-butylmetoxyphenol, butylated hydroxytoluene, octyl gallate, dodecyl gallate, ascorbic acid, lactic acid, citric acid, tartaric acid, an optionally substituted phenol, an optionally substituted hydroquinone, a possibly substituted quinone, an optionally substituted catechol, an optionally substituted aromatic amine, an optionally substituted metal complex of an aromatic amine, an optionally substituted triazine, an organic sulfide, an organic polysulfide, an organic dithiocarbamate, an organic phosphite or an organic Is phosphonate.

4. Mixture according to spoke 3, characterized in that the antioxidant is a compound of formula (6)

wherein the radicals R ^u , each independently of one another, are hydrogen, a linear or branched alkyl radical, an optionally substituted cycloalkyl radical, an optionally substituted aryl radical, a halogen, and wherein R ^{12 is} a linear or branched alkyl radical, an optionally substituted one Cycloalkyl radical or an optionally substituted aryl radical.

5. Mixture according spoke 3, characterized in that the antioxidant is a compound of formula (7)

where the radicals R, 13, each independently of one another, are hydrogen, a linear or branched alkyl radical, an optionally substituted cycloalkyl radical, an optionally substituted aryl radical, a halogen or a radical of the formula (8),

in which R ^{14 represents} a linear or branched alkyl radical having 1 to 6 carbon atoms.

6. Mixture according spoke 5, characterized in that the antioxidant of formula (9) is sufficient.

7. Mixture according to claim 3, characterized in that the antioxidant has the formula (10)

where o is an integer in the range from 1 to 4 and p is 1 or 2, where the radicals R ¹⁵ , each independently of one another, are hydrogen, a linear or branched alkyl radical or an optionally substituted cycloalkyl radical, where R ^{16 is} hydrogen or a denotes linear or branched alkyl radical and where R ^{17 represents} a monovalent alkyl group or a double-bonded alkylene group.

8. Mixture according to claim 3, characterized in that the antioxidant has the formula (11)

where the R ¹⁸ radicals, each independently of one another, are hydrogen, a linear or branched alkyl radical, an optionally substituted cycloalkyl radical, an optionally substituted aryl radical or a halogen.

9. Mixture according to claim 3, characterized in that it contains a compound of formula (12) as antioxidant

where the radicals R are an optionally substituted hydroxyphenyl radical.

10. Mixture according to at least one of the preceding claims, characterized in that the antioxidant of the formula (13) is sufficient

where the radicals R ²² , R ²³ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , each independently of one another, are hydrogen, a hydroxy group, a linear or branched alkyl group, an unsubstituted or a mono-, di-, or tri-alkyl-substituted phenyl group, a phenylalkyl group, a cycloalkyl group or an alkoxy group and the radical R ^{24 is} hydrogen, a hydroxy group, a linear or branched alkyl group, an unsubstituted or a mono-, di- or tri-alkyl-substituted phenyl group, a phenylalkyl group, an unsubstituted or mono-, di- or tri-alkyl-substituted cycloalkyl group, an alkoxy group or is a radical of formula (14)

wherein the radicals R ²² , R ²³ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ and R ^{29 have} the abovementioned meaning, and the radicals R ³⁰ and R ^{31 represent} hydrogen or a linear or branched alkyl group.

11. Mixture according to at least one of the preceding claims, characterized in that the antioxidant 1,4-dihydroxybenzene, 4-methoxyphenol, 2,5-dichloro-3,6-dihydroxy-l, 4-benzoquinone, 1,3,5- Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2,6-di-tert. butyl-4-methylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,2-bis- [3,5-bis- (1,1-dimethylethyl) -4-hydroxyphenyl-1-oxopropoxymethyl)] - 1,3-propanediyl ester, 2,2'-thiodiethylbis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl)] propionate, octadecyl-3- (3,5-di-tert-butyl -4-hydroxyphenyl) propionate, 3,5-bis- (1,1-dimethylethyl-2,2-methylenebis (4-methyl-6-tert-butyl) phenol, tris (4-tert-butyl -3-hydroxy-2,6-dimethylbenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) - trione, tris- (3,5-di-tert-butyl-4-hydroxy) -s-triazine-2,4,6- (1H, 3H, 5H) -trione or tert-butyl-3,5-dihydroxybenzene.

12. Mixture according to at least one of the preceding claims, characterized in that the antioxidant is methyl 3,5-di-tert-butyl-4-hydroxyphenyl propionate, diethylene glycol-di-3, 5-di-tert-butyl-4- hydroxyphenyl propionate, pentaerythritol tetra-3, 5-di-tert-butyl-4-hydroxyphenyl propionate, dimethyl- (3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, diphenyl- (3,5 -di-tert-butyl-4-hydroxybenzyl) phosphonate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenyl) -phosphoric acid phenyl ester, tris- (2,4-di-tert- butyl-phenyl) phosphite, dilauryl thiodipropionate or trinonyl phenyl phosphite.

13. Mixture according to at least one of the preceding claims, characterized in that the mixture further contains at least one synergistic, nitrogen-containing, sulfur-containing or phosphorus-containing costabilizer.

14. Mixture according to at least one of the preceding claims, characterized in that the polyvinyl acetal is crosslinked.

15. Mixture according to at least one of the preceding claims, characterized in that the polyvinyl acetal has a weight average molecular weight less than 1 000 000 g / mol.

16. Mixture according to at least one of the preceding claims, characterized in that the compound of the general formula (4) is n-butyraldehyde.

17. Mixture according to at least one of the preceding claims, characterized in that it contains plasticizers.

18. A method for producing a mixture according to at least one of the preceding claims, characterized in that components A.) to C.) are mixed with one another in any order.

19. The method according to claim 18, characterized in that the polyvinyl acetal A.) is prepared in the presence of components B.) and or C.).

20. Film containing a mixture according to at least one of the preceding claims 1 to 17.

21. Use of a film according to spoke 19 for the production of laminated safety glass.

22. Coating comprising a mixture according to at least one of claims 1 to 17.

23. Use of a mixture according to at least one of claims 1 to 17 for the production of ion-conductive intermediate layers for electrochromic systems.