CN1759125A - Crosslinked polyvinyl acetals - Google Patents

Abstract

The invention relates to methods for producing crosslinked polyvinyl acetals, according to which a polyvinyl alcohol (A1) containing carboxyl groups is crosslinked by (i) reacting the polymer (A1) with at least one polyaldehyde of formula R<SUP>9</SUP>(CHO)<SUB>n</SUB>, and (ii) at least partly esterifying groups of formula (1) and formula (4a) with each other, said steps being performed in any order. The invention further relates to methods for producing crosslinked polyvinyl acetals, according to which a polyvinyl alcohol (A2) is crosslinked by (i) reacting the polymer (A2) with at least one compound of formula (6), (ii) adding at least one compound of formula (4b), (iii) adding a polyaldehyde of formula (5), and (iv) at least partly esterifying groups of formula (1) and structural units derived from the compound of formula (4b) with each other, the radicals R<SUP>7</SUP>, R<SUP>8</SUP>, R<SUP>9</SUP>, R<SUP>10</SUP>, and R<SUP>11</SUP>, and the index n being defined as indicated in the description. Also disclosed are the crosslinked polyvinyl acetals obtained by means of the inventive method and particularly appropriate areas of application of said polymer.

Description

Cross-linked polyvinyl acetal

The present invention relates to crosslinked polyvinyl acetals, a process for their preparation and their use, in particular for laminated safety glass.

The modification of polyvinyl acetals by means of acetalization, in particular with n-butyraldehyde, is a long-known and frequently used reaction. Films of polyvinyl acetal, especially polyvinyl butyral, obtained in this way are used as laminated safety glass, especially for automotive windows due to their high light fastness and their good bonding ability (front and side windows) in the middle layer. This laminated glass offers a high degree of safety, since the elastic polyvinyl acetal film absorbs the mechanical energy in the event of impact stress and also keeps glass shards that may arise therein adhering to the film.

However, laminated safety glass based on conventional polyvinyl acetal types often does not have sufficient mechanical properties, especially at higher temperatures above 150°C. This problem is difficult to solve even by using polyvinyl acetal with a higher molecular weight, because in this case especially because of its processing problems (such as the formation of bubbles, the viscosity of polyvinyl acetal at the processing temperature Too high or too low, the properties are not constant during processing) and the actual feasibility reaches the limit.

For this reason, the European patent application EP 0211818 A1 recommends the use of a polyvinyl butyral, which is via an intermolecular diacetal bond in the case of an aldehyde with at least two aldehyde groups, It is cross-linked with butyral before or during the acetalization reaction of polyvinyl alcohol. However, this crosslinking, due to the higher reactivity of the aldehyde, leads to strongly crosslinked very high molecular weight and thus also partially insoluble polyvinyl butyral, which can only be very limited - if at all - —Suitable for preparing higher quality laminated safety glass. Regardless of this, those polyvinyl butyrals crosslinked by dialdehydes or polyaldehydes are not sufficiently stable under the conditions of polymer thermoplastic processing (such as extrusion), so depending on the temperature used, the residence time , shear rate and other factors will cause more or less obvious separation phenomenon (molecular weight decomposition) at the cross-linking position. These deficiencies in thermal stability make it difficult to obtain especially reproducible product quality, since the reactivity of the polymer is very sensitive to production variations, and they also lead to a deterioration of the mechanical properties of polyvinyl acetal , especially at higher temperatures.

Therefore, in view of the prior art, the object of the present invention was to provide a polyvinyl acetal having better mechanical properties, especially at higher temperatures, preferably above 150° C. At the same time, the polyvinyl acetals according to the invention should also be particularly suitable for the production of films and laminated safety glass with a higher quality, and thus also allow the material to be used during the processing into films and laminated safety glass. Performance, especially mechanical properties have better invariance.

It is also the object of the present invention to provide a process for the simple, comparatively large-scale and cost-effective preparation of the polyvinyl acetals according to the invention.

A further object of the present invention is to foresee particularly suitable applications of the polyvinyl acetals according to the invention.

These tasks, as well as others not expressly stated, but which can be deduced or seen without difficulty from what is discussed here, can be achieved by a method having all of the claims 1 or 5. The technical characteristics of the preparation method are to solve the cross-linked polyvinyl acetal. Reasonable developments of the method according to the invention fall within the scope of protection of the dependent claims referring to claims 1 and/or 5 . Furthermore, the present application also claims the polyvinyl acetals obtained by the process according to the invention and particularly interesting uses and fields of use for the purposes of use.

Polyvinyl acetals which are crosslinked and have better mechanical properties especially at higher temperatures, preferably above 150°C, can be obtained in a non-obvious manner by two methods, firstly a higher storage modulus, In the first method for preparing crosslinked polyvinyl acetal, a polymer (A1) containing the following structural units is crosslinked based on its total weight,

a) 1.0 to 99.9% by weight of structural units of formula (1)

wherein ^R represents hydrogen or methyl,

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

wherein ^R represents hydrogen or an alkyl group having 1 to 6 carbon atoms,

c) 0 to 70.0% by weight of structural units of formula (3)

wherein R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a group with a molecular weight of 1 to 500 g/mol,

d) 0.00001 to 30.0% by weight of structural units of the formula (4a)

wherein R ⁷ represents a single bond, an alkylene group having 1 to 10 carbon atoms or an optionally substituted arylene group having 6 to 12 carbon atoms, and R ⁸ represents hydrogen, COOH, having 1 to 10 carbon atoms Atomic alkyl or optionally substituted aryl having 6 to 12 carbon atoms,

And the following steps can be performed in any order,

(i) polymer (A1) is reacted with at least one polyaldehyde having formula (5),

R ⁹ (CHO) _n (5)

^R9 wherein represents a single bond or a group with 1 to 40 carbon atoms, and n is an integer greater than or equal to 2, and

(ii) at least partially interesterifying the groups of formula (1) and formula (4a),

In the second method for preparing crosslinked polyvinyl acetal, a polymer (A2) containing, based on its total weight, the following structural units is crosslinked,

a) 1.0 to 99.9% by weight of structural units of the formula (1),

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

c) 0 to 70.0% by weight of structural units of formula (3),

and among them

(i) polymer (A2) is reacted with at least one compound having formula (6),

wherein R ¹⁰ and R ¹¹ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms or an optionally substituted aryl group having 6 to 12 carbon atoms,

(ii) adding at least one compound of formula (4b),

wherein R ⁷ represents a single bond, an alkylene group having 1 to 10 carbon atoms or an optionally substituted arylene group having 6 to 12 carbon atoms, and R ⁸ represents hydrogen, COOH, having 1 to 10 Alkyl of carbon atoms or optionally substituted aryl having 6 to 12 carbon atoms,

(iii) adding a polyaldehyde having formula (5), and

(iv) at least partially interesterifying groups of formula (1) and structural units derived from compounds of formula (4b).

At the same time, the cross-linked polyvinyl acetal of the present invention also has a series of other advantages. These advantages include, inter alia:

=>The polyvinyl acetal according to the invention is distinguished by a better constancy of its material properties, in particular its mechanical properties, such as its storage modulus. This advantage is also observed in particular at higher temperatures, in particular above 150° C. Within the scope of the present invention, no change in crosslink density as described in EP0211818 A1 is observed, on the contrary, the polyvinyl acetals of the present invention, even at higher temperatures, especially at temperatures above 150°C, It also has significantly better crosslink density invariance.

=> In the polymers of the present invention, the presence of carboxyl groups or carboxylate groups linking the polymers results in significant stabilization of the linking points generated via the acetal bond bridges. Furthermore, they act as a buffer and in this way provide effective protection against the influence of potentially harmful acids, for example caused by hydrolysis products of the anti-binder.

=>The crosslinked polyvinyl acetal of the present invention can be produced on a large scale and at low cost by a simple method. Among these, in particular the relatively relaxed conditions of the crosslinking reaction and the short crosslinking times required for this can avoid the formation of those which usually lead to discoloration of the polymer and are therefore especially suitable for use as (transparent) laminated safety glass. Oxidation reactions and/or other thermally induced side reactions implying quality damage.

=>The cross-linked polyvinyl acetal of the present invention can be prepared quickly and under relaxed conditions, so that because the polyvinyl acetal has a very high molecular weight at the beginning, a very short extrusion distance or extrusion can be selected Departure dwell time.

=>Due to their characteristic properties, the polyvinyl acetals according to the invention are particularly suitable for laminated safety glass and can be produced in a simple manner, on a large scale and at low cost, in particular by extrusion. In connection with this, first of all, it has the advantage that by using the polyvinyl acetal according to the invention, bubble formation and fluctuations in properties can be avoided to the greatest extent during processing, and better optical and mechanical properties can be obtained by this method. High-performance and highly reproducible laminated safety glass.

According to a first aspect, the present invention relates to a polyvinyl acetal obtained starting from polymer (A1) comprising, by its total weight,

a) 1.0 to 99.9% by weight of structural units of formula (1)

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

c) 0 to 70.0% by weight of structural units of formula (3)

d) 0.00001 to 30.0% by weight, preferably 0.1 to 30.0% by weight, of structural units of the formula (4a)

Wherein the individual structural units can of course differ from each other, it is particularly preferred within the scope of the present invention that structural units of the formula (3) do not include structural units of the formulas (1), (2) and/or (4a).

The radicals R ¹ each independently of one another represent hydrogen or methyl, preferably hydrogen.

The radical ^R represents hydrogen or an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, ideally methyl, ethyl, n-propyl, isopropyl, n-butyl radical, sec-butyl, tert-butyl, n-pentyl or n-hexyl, preferably methyl or ethyl, particularly preferably methyl.

The radicals R ³ , R ⁴ , R ⁵ and R ⁶ are each independently of one another a radical with a molecular weight of 1 to 500 g/mol, ideally hydrogen, optionally branched, with 1 to 16 carbon atoms Aliphatic or cycloaliphatic groups, and which optionally contain one or more carboxylic acid amide groups and/or sulfonic acid groups.

The group ^R is a single bond, an alkylene group having 1 to 10 carbon atoms or an optionally substituted arylene group having 6 to 12 carbon atoms, ideally hydrogen or methylene, ethylene, n-propylene, isopropylene, n-butylene, sec-butylene, tert-butylene, n-pentylene or n-hexylene and which optionally have one or more COOH groups as substituents.

The radical ^R represents hydrogen, carboxyl or alkyl having 1 to 10 carbon atoms or optionally substituted aryl having 6 to 12 carbon atoms, ideally hydrogen or methyl, ethyl, n-propyl , isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl or n-hexyl, and which optionally contain one or more COOH groups as substituents. Particularly preferred groups ^R8 include hydrogen, methyl and _-CH2COOH .

Particularly preferred structural units of the formula (3) are derived from linear or branched olefins having 2 to 18 carbon atoms, (meth)acrylamide and/or vinylsulfonic acid. Among the olefins which have proven to be particularly advantageous are those which bear a terminal C-C double bond and preferably have 2 to 6 carbon atoms, especially ethylene. Furthermore, according to the present invention, the structural unit (3) derived from acrylamide allyl sulfonic acid (AMPS) can also bring about extremely beneficial effects.

A particularly preferred structural unit of the formula (4) can be obtained by acetalization of the structural unit of the formula (1) with glyoxylic acid.

According to a second aspect, the invention relates to a polyvinyl acetal obtained from polymer (A2) comprising, by its total weight,

a) 1.0 to 99.9% by weight of structural 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 of structural units of the formula (3).

Wherein the individual structural units can naturally differ from one another, it is particularly preferred within the scope of the present invention that the structural units of the formula (3) do not include the structural units of the formulas (1) and/or (2).

In addition, the groups R ¹ to R ⁶ are as defined above.

For the composition of polymer (A1) and/or (A2), preferably have the following content:

The total number of structural units of formula (2) is preferably in the range of 0.1 to 40 mol%, more preferably in the range of 0.5 to 25.0 mol%, and particularly preferably in the range of 1.0 to 15.0 mol%, all with the structural units of formulas (1) and (2) total count. Wherein, according to the first preferred embodiment of the present invention, the polymers (A1) and/or (A2) used contain 1.0 to 2.0 mol% of the formula (2) The structural unit. According to a second preferred embodiment of the present invention, the polymers (A1) and/or (A2) used contain 3.0 to 7.0 mol % of the formula (2) based on the total number of structural units of the formula (1) and (2). ) structural unit. According to a third preferred embodiment of the present invention, the polymers (A1) and/or (A2) used contain 10.0 to 15.0 mol% of the formula (1) and/or (2) based on the total number of structural units of the formula (2) The structural unit.

According to yet another particularly preferred embodiment of the present invention, polymers (A1) and/or (A2) contain, based on their total weight, >50.0% by weight, more reasonably >60.0% by weight, advantageously >70.0% by weight %, especially >80.0% by weight of structural units of formula (1) and/or (2). Use those with formula (1) and/or formula (2) that contain > 85.0% by weight, more reasonably > 90.0% by weight, advantageously > 95.0% by weight, especially > 99.0% by weight, based on their total weight Particularly advantageous results can be obtained with polymers (A1) and/or (A2) of the structural units.

Within the scope of the present invention, polymers (A1) and/or (A2) have a syndiotactic, isotactic and/or atactic chain structure. Furthermore, it can also be present in the form of random and block copolymers.

According to the invention, the viscosity of the polymers (A1) and/or (A2) is of secondary importance, and in principle both low and high molecular weight polymers (A1) and/or (A2) can be used. Within the scope of the present invention it has been established that polymers (A1) and/or (A2) have a viscosity in the range of 1 to 70 mPas, preferably 2 to 40 mPas, particularly preferably 3 to 30 mPas (according to Höppler at 20° C. and at 4 wt. % measured in aqueous solution, DIN 53015) is extremely favorable.

Furthermore, the molecular weight of polymers (A1) or (A2) is not particularly restricted, but it has been found for the purposes of the present invention that particularly preferably polymers (A1) and/or (A2) have a weight-average molecular weight of at least 20000 g/mol. Here, the weight-average molecular weight is preferably determined by means of gel permeation chromatography, expediently using polyethylene oxide standards.

The preparation of the polymers (A1) and/or (A2) to be used in the invention can be carried out simply in a multistage process. In a first step, the corresponding vinyl ester is polymerized free-radically in a suitable solvent, usually water or an alcohol such as methanol, ethanol, propanol and/or butanol, and using a suitable free-radical initiator. If the polymerization is carried out in the presence of free-radically copolymerizable monomers, the corresponding vinyl ester copolymers are obtained.

Then in a second step, the vinyl ester (co)polymer is saponified, usually by transesterification with methanol, where known methods can be used, e.g. by varying the catalyst concentration, reaction temperature and/or reaction time to Adjust saponification degree. For further details reference may be made to general specialist literature, in particular Ullmann's Encyclopedia of Industrial Chemistry, Fifth Edition, CD-Rom Wiley-VCH, 1997, Keyword: Poly (VinylAcetals) and references cited therein.

Starting from the polyvinyl alcohol obtained in this way, polymer (A1) can then be prepared by reaction and acetalization with a compound of formula (4b),

wherein R ⁷ represents a single bond, an alkylene group having 1 to 10 carbon atoms or an optionally substituted arylene group having 6 to 12 carbon atoms, and R ⁸ represents hydrogen, COOH, having 1 to 10 carbon atoms atoms or an optionally substituted aryl group having 6 to 12 carbon atoms.

The reaction of polyvinyl alcohol with compound (4b) is preferably carried out in at least one inert solvent, wherein the term "inert solvent" is understood to mean a solvent which does not interfere or even prevent the desired reaction process under the respective reaction conditions. A particularly desirable solvent in this context is water.

Among them, the reaction can be carried out more favorably in the presence of an acidic catalyst. Suitable acids include both organic acids, such as acetic acid, and inorganic acids, such as hydrochloric acid, sulfuric acid and/or nitric acid, and the use of hydrochloric acid, sulfuric acid and/or nitric acid has proven to be particularly suitable industrially. The reaction is preferably carried out in such a manner that polyvinyl alcohol is placed in an aqueous solution, compound (4b) is added to the solution and then an acidic catalyst is added dropwise.

Within the scope of the first embodiment of the invention, the crosslinked polyvinyl acetal is obtained by carrying out the following operations in any order,

(i) polymer (A1) is reacted with at least one polyaldehyde having formula (5), and

R ⁹ (CHO) _n (5)

(ii) At least partially esterifying the groups of formula (1) and formula (4a) with each other.

Wherein R ⁹ represents a single bond or a group with 1 to 40 carbon atoms, preferably an aliphatic or alicyclic group with ideally 1 to 20, preferably 1 to 12, particularly preferably 2 to 10 carbon atoms and/or aromatic groups.

The index n is an integer greater than or equal to 2, preferably in the range of 2 to 10, more preferably in the range of 2 to 6, particularly preferably in the range of 2 to 3. According to a particularly preferred embodiment of the invention, n is 2.

Compounds of formula (5) which are particularly suitable for the present invention include glyoxyl, malondialdehyde, n-succinaldehyde, glutaraldehyde, n-adipaldehyde, n-pimelic aldehyde, n-suberaldehyde, n-azelaaldehyde, n- Decanedial, n-undecanedialdehyde, n-dodecanedialdehyde, 4,4'-ethylenedioxybenzaldehyde and 2-hydroxyadipaldehyde, particularly preferably glutaraldehyde and n-azelaldehyde.

Within the scope of the present invention, the amount of polyaldehyde (5) can in principle be selected arbitrarily, but for the purpose of the present invention, it is particularly preferred to use 0.001 to 1.0% by weight, more reasonably 0.005 to 1.0% by weight, based on the total weight of polymer (A1). 2.0% by weight, especially 0.01 to 1.0% by weight of polyaldehyde (5).

Steps (i) and (ii) can be carried out in any order, that is, step (i) can be performed first, step (ii) second, or step (ii) can be followed by step (i), or both steps can be performed simultaneously. For the purposes of the present invention, however, it has proven particularly advantageous to carry out step (i) first and then step (ii).

Within the scope of a particularly preferred embodiment of the invention, at least one compound of the formula (6) can also be added at any time.

The groups R ¹⁰ and R ¹¹ are each independently of each other hydrogen, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 12 carbon atoms. Wherein, these alkyl and aryl groups may be substituted by one or more hydroxyl groups, sulfonic acid groups and/or halogen atoms such as fluorine, chlorine, bromine, iodine. Among the preferred compounds of formula (6) are formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, 2-ethoxybutyraldehyde, paraldehyde, 1,3,5-trioxane, Capronaldehyde (Capronaldehyde), 2-ethylhexanal, nonanal, 3,5,5-trimethylhexanal, 2-formyl-benzenesulfonic acid, acetone, ethyl methyl ketone, butyl ethyl ketone and/or ethylhexyl ketone.

Within the scope of the present invention, it has proven to be particularly preferred to use aldehydes, ie compounds of the formula (6) in which R ¹⁰ =hydrogen and R ¹¹ =hydrogen, methyl, ethyl, n-propyl or isopropyl, preferably formaldehyde and/or Or n-butyraldehyde, particularly preferably n-butyraldehyde is used.

The ratio of components (5) and (6) is preferably selected as follows

(1) 95.00 to 99.99 parts by weight of at least one compound (6),

(2) 0.01 to 5.00 parts by weight of at least one polyaldehyde (5),

The parts by weight stated therein preferably make up 100.00 parts by weight.

The reaction of polymer (A1) with compounds (5) and/or (6) is preferably carried out in at least one inert solvent, wherein the term "inert solvent" is understood to mean that under the respective reaction conditions the desired solvent for the reaction process. A particularly desirable solvent in this context is water.

In addition, the reaction can be more advantageously carried out in the presence of an acidic catalyst. Suitable acids include both organic acids, such as acetic acid, and inorganic acids, such as hydrochloric acid, sulfuric acid and/or nitric acid, and the use of hydrochloric acid, sulfuric acid and/or nitric acid has proven to be particularly suitable industrially. The reaction is preferably carried out by placing the polymer (A1) in an aqueous solution, adding the compounds (5) and/or (6) to the solution and then adding the acidic catalyst dropwise.

Within the scope of a second embodiment of the invention, crosslinked polyvinyl acetals are obtained by,

(i) polymer (A2) is reacted with at least one compound having formula (6),

(ii) adding at least one compound of formula (4b),

(iii) adding a polyaldehyde of formula (5), and

(iv) at least partially interesterifying groups of formula (1) and structural units derived from compounds of formula (4b).

Wherein, the compounds having the formulas (4b), (5) and (6) are as defined above.

Esterification processes (ii) and/or (iv) can be carried out in a simple manner, but it turns out within the scope of the invention, particularly preferably in the optional presence of at least one softener and at temperatures between 80 and 280° C., The thermal crosslinking process is preferably carried out at a mass temperature of 120 to 280° C., particularly preferably 140 to 260° C.

The thermal crosslinking of polyvinyl acetals can be carried out using all heatable equipment known to the skilled person, such as furnaces, kneaders, extruders, molding presses or autoclaves. However, preference is given to carrying out the thermal crosslinking process in extruders or kneading devices, since these ensure good homogeneous mixing with the softener contained in a preferred embodiment. The crosslinking process can be discerned here by the fact that crosslinked polyvinyl acetal has a higher molecular weight compared to uncrosslinked polyvinyl acetal.

The degree of crosslinking can - depending on the purpose of use - be chosen at will. However, it is particularly preferred within the scope of the present invention that at least 10 mol %, preferably at least 20 mol %, more preferably at least 30 mol %, particularly preferably at least 40 mol %, of all carboxyl groups originally contained in the polyvinyl acetal are esterified. Wherein, the content of the carboxyl group is based on the total weight of the crosslinked polyvinyl acetal, preferably less than or equal to 10.0% by weight and more preferably 0.00001 to 10.0% by weight, particularly preferably 0.01 to 5.0% by weight, extremely preferably 0.01 to 2.0% by weight in the weight percent range.

In a preferred embodiment, the crosslinked polyvinyl acetal of the present invention contains a softener. All softeners known to the skilled person can be used as softeners. Emollients can be used in conventional amounts known to the skilled person. Known softeners suitable for polyvinyl acetals, especially polyvinyl butyrals, are esters of aliphatic mono- and dicarboxylic acids with monohydric or polyhydric alcohols or oligoalkylene glycol ethers, Phosphate esters and various phthalates such as those disclosed in US-A5137954. However, preference is given to using di-, tri- and tetraethylene glycols and diesters of aliphatic monocarboxylic acids, dialkyl adipates and the alkylene glycols and polyalkylene glycols described in DE-A-10100681 not previously published of dibenzoates.

Possible fields of application of the crosslinked polyvinyl acetals according to the invention will be apparent to the skilled person. They are particularly suitable for all previously described applications of crosslinked polyvinyl acetals, in particular polyvinyl formal and/or polyvinyl butyral. Particularly preferred fields of application include their use as films, in particular for laminated glass, and they are preferably producible by direct extrusion by means of wide-slit nozzles. Further details concerning the extrusion of polyvinyl acetal and the production of polyvinyl acetal films, in particular polyvinyl butyral films, are sufficiently known to the skilled person from the specialist literature.

A particularly preferred field of application of the polyvinyl acetals according to the invention within the scope of the invention is planar structures, in particular films preferably having a thickness of 0.5 μm to 1 mm. The films of the invention may also contain other conventional additives, such as oxidation stabilizers, UV stabilizers, pigments, fillers, pigments and/or antiblocking agents.

Furthermore, the polyvinyl acetals according to the invention are also particularly suitable for coating substrates, in particular wood, metal, plastics, glass, textiles, paper, leather and also ceramic and mineral substrates. The content of the invention therefore also consists in coatings comprising polyvinyl acetals according to the invention.

The coating may additionally contain polymeric resins, softeners, pigments, fillers, stabilizers, bond improvers, rheology modifiers, additives affecting pH and/or capable of catalyzing the polyvinyl acetal of the present invention and other Additives for chemical reactions between polymer resins and other polymer resins.

The coating process according to the invention can be carried out both in the form of a powder which is subsequently melted and crosslinked, preferably at higher temperatures, by known methods, or by means of coating methods known to the skilled person, preferably in the form of an organic solution conduct. During coating from solution, the polyvinyl acetal to be crosslinked according to the invention and optionally other binders and optionally other components such as softeners, pigments, fillers, stabilizers Additives, adhesion improvers, rheology modifiers are dissolved together in a solvent or solvent mixture and then applied to the substrate to be coated. The crosslinking process according to the invention is carried out ideally at a temperature of from 20 to 200° C., preferably after evaporation of the solvent. Among them, the addition of organic and/or inorganic acids that can lower the pH value is beneficial to the progress of the crosslinking reaction.

When used in coatings, the crosslinking process results in improved solvent resistance and increased molecular weight of the coating compared to uncrosslinked polyvinyl acetal.

According to a further aspect of the invention, the polyvinyl acetals of the invention are also particularly suitable for the preparation of ion-conducting intermediate layers for electrochromic systems.

Claims (22)

1. method for preparing cross-linked pioloform, wherein need polymkeric substance (A1), and this polymkeric substance contains with lower unit in its gross weight:

A) the structural unit of 1.0 to 99.9 weight % with formula (1)

R wherein ¹Expression hydrogen or methyl,

B) structural unit of the formula of 0 to 99.0 weight % (2)

R wherein ²Expression hydrogen or have the alkyl of 1 to 6 carbon atom,

C) structural unit of the formula of 0 to 70.0 weight % (3)

R wherein ³, R ⁴, R ⁵And R ⁶Be molecular weight separately independently of each other at 1 to 500g/mol group,

D) structural unit of the formula of 0.00001 to 30.0 weight % (4a)

R wherein ⁷Be singly-bound, have the alkylidene group of 1 to 10 carbon atom or have 6 to 12 carbon atoms and optional substituted arylidene, and R ⁸Be hydrogen, COOH, have the alkyl of 1 to 10 carbon atom or have 6 to 12 carbon atoms and optional substituted aryl,

It is characterized in that, carry out following steps in any order,

(i) polymkeric substance (A1) and at least a polyacetals reaction with formula (5),

R ⁹(CHO) _n (5)

R wherein ⁹Expression singly-bound or have the group of 1 to 40 carbon atom, and n be more than or equal to 2 integer and

The (ii) group of interesterification formula (1) and formula (4a) at least in part.

2. the method for claim 1 is characterized in that, is added at least a compound with formula (6) at any time,

R wherein ¹⁰And R ¹¹Be hydrogen independently of each other separately, have the alkyl of 1 to 10 carbon atom or have the optional substituted aryl of 6 to 12 carbon atoms.

3. as claim 1 and/or 2 described methods, it is characterized in that, wherein use R ⁸The polymkeric substance of=hydrogen (A1).

4. as at least one described method in the above-mentioned claim, it is characterized in that, in the used polymkeric substance (A1), R ⁷For singly-bound or have the alkylidene group of 1 to 4 carbon atom.

5. the method for preparing cross-linked pioloform, wherein want cross-linked polymer (A2), and this polymkeric substance contains with lower unit in its gross weight:

A) the structural unit of 1.0 to 99.9 weight % with formula (1)

R wherein ¹Expression hydrogen or methyl,

B) structural unit of the formula of 0 to 99.0 weight % (2)

R wherein ²Expression hydrogen or have the alkyl of 1 to 6 carbon atom,

C) structural unit of the formula of 0 to 70.0 weight % (3)

R wherein ³, R ⁴, R ⁵And R ⁶Be molecular weight separately independently of each other at 1 to 500g/mol group,

It is characterized in that,

(i) polymkeric substance (A2) and at least a compound reaction with formula (6),

R wherein ¹⁰And R ¹¹Be hydrogen independently of each other separately, have the alkyl of 1 to 10 carbon atom or have the optional substituted aryl of 6 to 12 carbon atoms,

(ii) add at least a compound with formula (4b),

R wherein ⁷The expression singly-bound has the alkylidene group of 1 to 10 carbon atom or has 6 to 12 carbon atoms and optional substituted arylidene, and R ⁸Represent hydrogen, COOH, have the alkyl of 1 to 10 carbon atom or have 6 to 12 carbon atoms and optional substituted aryl,

(iii) add polyacetals with formula (5),

R ⁹(CHO) _n (5)

R wherein ⁹Expression singly-bound or have the group of 1-40 carbon atom, and n be more than or equal to 2 integer and

(iv) interesterification formula (1) and derived from the group of the structural unit of formula (4b) compound at least in part.

6. method as claimed in claim 5 is characterized in that, uses at least a have a formula (4b) and R ⁸The compound of=hydrogen.

7. as claim 5 and/or 6 described methods, it is characterized in that, use at least a have formula (4b) and R wherein ⁷For singly-bound or have the compound of the alkylidene group of 1 to 4 carbon atom.

8 as above-mentioned claim at least one described method, it is characterized in that, use the compound (5) of n=2 wherein or 3.

9. as at least one described method in the above-mentioned claim, it is characterized in that, use wherein R ⁹Compound (5) for the aliphatic series that has 1 to 12 carbon atom, alicyclic and/or aromatic group.

10. method as claimed in claim 9 is characterized in that, uses glutaraldehyde and/or positive azel aldehyde as compound (5).

11. as at least one described method in the above-mentioned claim, it is characterized in that, use butyraldehyde-n as compound (6).

12. as at least one described method in the above-mentioned claim, it is characterized in that, use

At least a compound (6) of (1) 95.00 to 99.99 weight parts,

At least a polyacetals (5) of (2) 0.01 to 5.00 weight parts,

Wherein said weight part will be supplied 100.00 weight parts.

13. at least one described method in the claim is characterized in that as described above, is carrying out esterification process under the optional condition that has an at least a tenderizer and under in 80 to 280 ℃ the temperature of charge (ii) or (iv).

14. method as claimed in claim 13 is characterized in that, carries out cross-linking process in forcing machine, kneader device or other heatable equipment.

15. by the cross-linked pioloform that obtains as the described method of at least one item in the above-mentioned claim.

16. polyvinyl acetal as claimed in claim 15 is characterized in that, in the gross weight of polyvinyl acetal, its esterification with nonesterified total amount smaller or equal to 10.0 weight %.

17., it is characterized in that wherein containing tenderizer as claim 15 and/or 16 described polyvinyl acetals.

18. contain moulded piece just like at least one described polyvinyl acetal in the claim 15 to 17.

19. contain film just like at least one described polyvinyl acetal in the claim 15 to 18.

20. film as claimed in claim 19 is used to prepare the purposes of laminated safety glass.

21. contain coating just like at least one described polyvinyl acetal in the claim 15 to 17.

22. as at least one described polyvinyl acetal in the claim 15 to 17 be used to prepare that the electrochromism system is used, have a purposes in the middle layer of ionic conduction ability.