WO2018167310A1

WO2018167310A1 - Method for functionalizing acrylate polymers in the absence of a solvent, and modified acrylate polymers obtainable by said method

Info

Publication number: WO2018167310A1
Application number: PCT/EP2018/056758
Authority: WO
Inventors: Walter Degelmann
Original assignee: Lohmann Gmbh & Co. Kg
Priority date: 2017-03-17
Filing date: 2018-03-16
Publication date: 2018-09-20
Also published as: EP3596139A1; DE102017105755A1

Abstract

Disclosed is a method for functionalizing acrylate polymers using a functionalizing agent at temperatures of 50 °C to 350 °C, said agent containing at least one primary or secondary amino group which is reacted with a carboxyl group of the acrylate polymers to obtain an amide function, the reaction taking place in the absence of a solvent. Also disclosed are modified acrylate polymers that can be obtained by said method.

Description

METHOD OF FUNCTIONALIZING ACRYLATE POLYMERS IN THE ABSENCE OF A SOLVENT AND MODIFIED ACRYLATE POLYMERS AVAILABLE BY THE METHOD

Technical area

The present invention relates to a process for functionalizing acrylate polymers in the molten state.

State of the art

Acrylate polymers, that is, homo- and copolymers of acrylic acid, methacrylic acid, and various esters of these acids, are well known in the art and are widely used in a wide variety of applications. Important monomers in this context are, for example: methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, ferric acid. Butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, acrylic acid and methacrylic acid. Important comonomers in the production of acrylate polymers include acrylonitrile, methacrylonitrile, ethylene, styrene, 1, 3-butadiene, 1, 2-butadiene, vinyl acetate, vinyl propionate, vinyl chloride and vinylidene chloride.

All acrylate polymers share as a characteristic the presence of carboxyl or corresponding ester groups and thus represent, structurally speaking, derivatives of carboxylic acids. These functional groups are thus basically available for functionalization reactions of the polymers mentioned. Such reactions are also known in the art and are usually carried out in solutions; By way of example, only the saponification of the ester function is mentioned here.

In addition, numerous polyfunctional acrylate monomers are known which can be used in the preparation of acrylate monomers; Examples which may be mentioned here are di- and triacrylates (eg ethylene glycol diacrylate, trimethylolpropane triacrylate), hydroxy-substituted acrylates (eg 2-hydroxyethyl acetate), ethers (eg ethyl diglycol acrylate), amines (eg dimethylaminoethyl acrylate, tert-butylaminoethyl methacrylate), epoxy-derivatized acrylates (eg glycidyl acrylate, Glycidyl methacrylate) and sulfonic acids (eg 2-sulfoethyl methacrylate). The structural latitude of available acrylate monomers and the wide range of possible uses of comonomers in the production of acrylate polymers already allow a wide variety of reaction products, ie, acrylate polymers, in the prior art Selection of the monomers used in the preparation can be specifically influenced.

Furthermore, the properties of acrylate polymers can be specifically influenced by polymer-analogous reactions and / or crosslinking reactions (with the finished acrylate polymers as starting materials for further functionalization reactions).

Acrylate polymers obtained with the participation of polyfunctional comonomers are of particular interest when it comes to carrying out crosslinking reactions on the polymers. Depending on the nature of the reactive group introduced into the macromolecule by the multifunctional acrylate, such crosslinking reactions are known using second components (which react with the functional groups present) or else radiation curing reactions.

Crosslinking reactions with secondary components (crosslinkers) usually take place in solutions. Such reaction systems usually allow a good mixing of the reactants and a good temperature control of the reactions. However, it can be problematic to remove the solvent from the finished reaction product. Crosslinking increases the molecular weight of the polymers, and thus increases their ability to retain small molecules (such as solvents) in the molecular structure. This is undesirable for many technical applications, since the properties of the polymer can change with the presence of such solvent residues and, in particular during use (by evaporation), uncontrolled and undesired property changes can occur. Even under environmental aspects such a behavior may be problematic. In addition, thicker layers of solvent can generally produce only limited. The drying process is increasingly cost-intensive or high residual contents of solvent remain in the end product.

Such problems do not necessarily arise with the use of radiation curing reactions, since these reactions can also be carried out with solventless systems. However, the limiting factor here is the layer thickness of the system, since the penetration depth of the jets causing the reactions can not be arbitrarily increased. Thus, such reactions are often only in thin layers in a homogeneous, controlled manner to perform. Functionalizations for acrylates are well known and are usually carried out in solvents. Moreover, they are linked to the existence of defined, functional groups; that is, already in the polymerization, it is necessary to make a preselection, to select certain functional monomers that are ready for the corresponding subsequent reaction. European Patent No. EP 1 627 023 B discloses a process for the solvent-free preparation of UV-crosslinkable polyacrylates. This is based on the use of copolymerizable photoinitiators, ie, specific monomers which are incorporated into the acrylate polymer during the polymerization process and allow its crosslinking by UV action. An additional crosslinking agent is not used here. European Patent Application No. 1 234 851 discloses a crosslinkable rubber composition of a nitrile group-containing rubber further containing monomer units of an ethylenically unsaturated dicarboxylic acid monoalkylester monomer, wherein a polyamine can serve as a crosslinking agent and a basic crosslinking accelerator is used. The dicarboxylic acid monoalkyl ester monomer units, which differ structurally from the polyacrylate units of the present invention, serve as reactive groups for linking via the crosslinking agent.

Presentation of the invention

Starting from the known prior art, it is an object of the present invention to provide a process for the functionalization of acrylate polymers, which manages without the action of radiation and without solvents. There is a considerable practical advantage of being able to resort to a pool of standard polymers and corresponding processes which allow tailor-made adjustments to the particular application in a late stage of the value added directly from the melt.

Homopolymer and copolymers of acrylic acid and / or methacrylic acid and their esters are understood as "acrylate polymers" in the sense of the invention, in which case the radicals forming the ester group can not bear any further functionality (ie represent hydrocarbon radicals) or be functionalized. Essentially all acrylic and methacrylic acid esters known in the art as constituents of acrylate polymers are suitable.

The acrylate polymer may further be selected from homo- and copolymers of methyl, ethyl, butyl, 2-ethylhexyl, cyclohexyl, dodecyl, 2-hydroxyethyl or 2-dimethylaminoethyl ester of acrylic or methacrylic acid and copolymers of these monomers become. The copolymers may also have other comonomers, which do not originate from the group of acrylate monomers.

Particularly preferred are homopolymers of the monomers methyl acrylate, ethyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, as well as copolymers containing these monomers as comonomers.

In addition, the acrylate polymers to be functionalized according to the invention may also have further comonomer constituents, which themselves do not have to represent acrylic acid or methacrylic acid derivatives. Essentially all monomers which are suitable as comonomers for acrylate polymers in the prior art are suitable here. Examples of suitable comonomers include acrylonitrile, methacrylonitrile, styrene, 1, 3-butadiene, 1, 2-butadiene, vinyl acetate, vinyl propionate, vinyl chloride and vinylidene chloride. In addition, the acrylate polymers may contain between 0 and up to 100 mol%, preferably between 0 and 20 mol%, more preferably between 0 and 10 mol% of free carboxy groups.

The acrylate polymers of the present invention preferably contain no ethylenic dicarboxylic acids or their monoalkyl or dialkyl esters as comonomers.

Such acrylate polymers according to the invention in the absence of solvents (ie, in the melt) and in a temperature range between 50 ° C and 350 ° C, preferably between 100 ° C and 200 ° C, optionally in the presence of a catalyst, with a functionalizing agent implemented.

As it has surprisingly been found, amines very widely allow the general modification of acrylates in the melt. The present invention discloses possibilities that go well beyond the illustrated prior art.

Functionalizing agents in the context of the invention are organic compounds having at least one primary (-NH ₂ ) or secondary (-NH) amino function or amino group. This primary or secondary amino group reacts in the course of the reaction with an ester function of the acrylate polymer to form an amide function (carboxylic acid amide). The reaction thus leads to the replacement of a side chain on the polyacrylate backbone, wherein a new side chain (from an amide function) is introduced in each case for each original side chain (from an ester function) which is removed from the macromolecule.

Depending on the design of the functionalizing agent, it is thus possible to specifically modify the structure of the acrylate polymer. In the simplest case, when the functionalizing agent is an organic compound other than the said primary or secondary amino functionality has no further functionality, thus easy replacement of an ester takes place against an amide side chain.

In another embodiment, the functionalizing agent is an organic compound having at least one additional functionality to the primary or secondary amino function per molecule. In this way, the inventive method allows the targeted introduction of further functionalities in the acrylate polymer.

The functionalities to be introduced into the acrylate polymer in this way are manifold. At best, a limitation can result from an undesired interaction of the functionalities involved or from the resulting undesirable reactions. In a further embodiment, the functionalizing agent is an organic di- or polyamine having at least two or more primary and / or secondary amino groups per molecule. The functionalization in this case represents a crosslinking of the acrylate polymer.

The process according to the invention can be carried out in a batch process or in a continuous process, for example in a heatable extruder The reaction can in principle be carried out in all apparatuses suitable for carrying out reactions in the molten state The reaction can be carried out continuously or batchwise and under normal pressure as well as elevated / reduced pressure Suitable apparatuses are, for example, continuous single- and multi-shaft kneaders such as kneading autoclaves, Buss kneaders or twin-screw extruders The reaction can also be carried out in a stirred autoclave having intensive mixing but low shear melt mixing means, which is particularly useful when relatively volatile compounds are used.

A particularly preferred method for carrying out the process is the continuous melt extrusion in single or twin screw extruders, because in this method a particularly intensive mixing is possible. The reaction can therefore be carried out with tough melts, which can be carried out at low reaction temperatures. An optimal mixture without high shear also ensures a very uniform mixing of the reaction mixture. Also additives such as dyes are evenly distributed in the polymer. The residence time in the heated zone is limited to an optimum, in order to avoid an unnecessary temperature load on the reaction mixture. The method includes the steps of contacting the acrylate polymer in a molten state with the functionalizing agent, optionally in the presence of a catalyst, mixing the components, and maintaining a reaction temperature in the mixture in the range between 50 ° C and 350 ° C ° C, preferably 100 ° C and 200 ° C, for a sufficient time for the implementation of the components period.

Suitable catalysts are in principle all compounds which are known to the person skilled in the art as suitable catalysts for the reaction of a carboxylic acid ester into a carboxylic acid amide (see, for example, F. Körte (ed.), Methodicum Chimicum, Volume 6: CN compounds, me, Stuttgart 1974, Chapter 17, or R. Larock (ed.), Comprehensive Organic Transformations, 2nd Ed., Wiley-VCH, New York 1999, Chapter "Interconversion of Nitriles, Carboxylic Acids and Derivatives"), and those of their own physical properties are suitable to be used under the process conditions described above.

Particularly suitable catalysts according to the invention are Brönstedt acids, in particular organic acids, and in particular carboxylic acids, preference being given to those carboxylic acids which are not volatile under the process conditions. A suitable embodiment here represent, for example, hydrocarbon resins with carboxy functionality or a plurality of carboxyl functionalities per molecule.

Alternatively, it is also possible to use representatives of the class of Lewis acids which are also known to be suitable for the purpose of reacting a carboxylic acid ester in a carboxylic acid amide.

The catalyst can in this case be used in ranges between 0.5 and 10% by weight, preferably between 0.5 and 5% by weight, based on the weight of the reactants used (acrylate polymer and functionalizing agent). Even larger or smaller weight ratios can - if necessary, be realized depending on the reaction conditions and reactants. Suitable acrylate polymers are in particular polymers having a molecular weight in the range between 10,000 g / mol and 2,000,000 g / mol, preferably between 10,000 g / mol and 200,000 g / mol, in question. However, acrylate polymers outside of these ranges can also be functionalized by the process of the present invention, provided the corresponding acrylate polymers are in molten state at the temperatures of the process. In another embodiment, the acrylate polymer is solid at room temperature. As functionalizing agents it is possible to use both aliphatic and aromatic primary or secondary amines. These amines may contain one or more other functional groups characterized by being stable in the presence of a corresponding amino function. The functionalizing agents are usually used in a molar proportion of 0.1 to 100 mol%, based on the content of carboxy or carboxylic ester functions in the acrylate polymer used.

In another embodiment, the functionalizing agents are aliphatic or aromatic, primary or secondary amines. In a preferred embodiment, they are aliphatic or aromatic, primary or secondary diamines. In a further preferred embodiment, these are aliphatic or aromatic, primary or secondary polyamines.

By means of the process according to the invention, it is possible to functionalize acrylate polymers over a wide range, i.e. to introduce into the macromolecule those functional groups which can not be introduced by the copolymerization of a corresponding comonomer. Such functionalizations include both polymer-analogous reactions (ie, reactions in which the molecular weight of the macromolecule does not change significantly) and crosslinking reactions (in which the molecular weight increases), as well as the combination of macromolecules with correspondingly functionalized solids (approximately corresponding functionalized silica, silicates or other inorganic or organic solids suitable for surface functionalization, carbon blacks, fullerenes, etc. provided with primary or secondary amino functions) or biomolecules (proteins, aminosaccharides, and the like). Such a functionalization can also be carried out on molds or workpieces of appropriate composition in order to prepare their surfaces for a corresponding reaction. For example, amino functions via plasma

Functionalization reactions are introduced on corresponding surfaces, which can then react with acrylate polymers. This can be used, for example, to improve the adhesion of acrylate polymers to the surfaces of such workpieces.

In addition to the process for functionalization, the invention also relates to the structurally modified acrylate polymers obtained by the process.

Detailed Description of Preferred Embodiments Example 1: Reaction of acResin® DS 3500 with Jeffamine® M-2070: Increasing the water solubility by introducing a hydrophilic side chain

Starting materials: acResin® DS 3500 (BASF) is a polybutyl acrylate with a molecular weight of approx. 50,000 g / mol. Existing carboxyl groups can be determined by titration with KOH; the consumption is 52 mg KOH per g of polymer. According to the manufacturer, the product is miscible with water to less than 10%.

Jeffamine® M-2070 (Huntsman) is a mixed poly (ethylene oxide) (propylene oxide) amine (polyether amine) of the following structure

with a molecular weight of about 2,000 g / mol and a ratio y / x of 10/31, that is, it contains predominantly polyethylene oxide units and is thus hydrophilic.

The introduction of polyetheramide side chains in the polybutyl acrylate molecule thus leads to an increase in the hydrophilic character of the entire macromolecule and thus improved miscibility / solubility in water. In order to clearly detect a chemical bond, reference samples were prepared, in the exemplary embodiments marked with *. These were not heated, so there is no chemical reaction; maximum are here salt bonds or hydrogen bonds before; By adding water they dissolve again.

Reaction: 20 g of acResin DS 3500 were initially introduced and mixed with 2 g (Example C2 and C2 *), 5 g (Example C5 and C5 *) and 10 g (Example C10 and C10 *) M-2070, heated or just mixed.

C2: 20 g ac Resin DS 3500 heated with 2 g Jeffamine M-2070

20.0 g acResin DS 3500 were heated together with 2.0 g Jeffamine M-2070 to 160 ° C for 40 min. After cooling, 1 g of the product was removed without further work-up and admixed with 9.0 g of distilled water. Much of the product remained unresolved. C5: 20 g ac Resin DS 3500 heated with 5 g Jeffamine M-2070

20.0 g of acResin DS 3500 were heated together with 5.0 g of Jeffamine M-2070 to 160 ° C. for 40 min. After cooling, 1 g of the product was removed without further work-up and admixed with 9.0 g of distilled water. It formed overnight a milky homogeneous solution. C10: 20 g ac Resin DS 3500 heated with 10 g Jeffamine M-2070

20.0 g acResin DS 3500 were heated to 160 ° C. together with 10.0 g Jeffamine M-2070 for 40 min. After cooling, 1 g of the product was removed without further work-up and admixed with 9.0 g distilled water. It formed overnight a translucent homogeneous solution. C2 *: 20 g ac Resin DS 3500 with 2 g Jeffamine M-2017 without heating

0.91 g of acResin DS 3500 and 0.09 g of Jeffamine M-2070 were mixed and treated with 9.0 g of distilled water. The much larger part of the mixture remained unresolved.

C5 *: 20 g ac Resin DS 3500 with 5 g Jeffamine M-2070 without heating

0.8 g of acResin DS 3500 and 0.2 g of Jeffamine M-2070 were mixed and added with 9.0 g of distilled water. The much larger part of the mixture remained unresolved.

C10 *: 20 g ac Resin DS 3500 with 10 g Jeffamine M-2070 without heating

0.65 g of acResin DS 3500 and 0.35 g of Jeffamine M-2070 were mixed and added with 9.0 g of distilled water. The much larger part of the mixture remained unresolved.

Result: The process according to the invention leads to an exchange of the butyl ester for polyetheramide side chains, which change its properties (water miscibility / solubility) with increasing concentration in the macromolecule.

Example 2: Reaction of Acronal® 4F with meta-xylenediamine: Cross-linking of a Polvacrylate by Crosslinking Starting Materials: Acronal® 4F (BASF) is a polybutyl acrylate with a molecular weight of 40,000 g / mol (without titratable acid groups).

Meia-xylylenediamine (MDXA) is a primary amine with two amino functions per molecule.

Foral® AX (Eastman) is a fully hydrogenated, acidic hydrocarbon resin used as a catalyst.

Foral®NC is a partially neutralized hydrocarbon resin (acid number 120-138), which is used as a catalyst.

Execution of the reaction:

1.5 g of Foral AX and 18.5 g of Acronal 4F are heated to 190 ° C. with 1.0 g of MXDA heated. Net are initially 21, 0 g of substance before. After a few minutes, there were signs of gagging.

The use of 1, 0 g (7.35 mmol) MXDA results in a displacement of the butanol from the ester bond and build up an amide bond to a splitting of 1, 09 g of butanol or to a corresponding weight loss at 100% conversion.

Heating (190 ° C) and control weighing monitored the progress of the reaction:

The determined weights show the occurrence of a conversion to the amide; The fairly long times may also be related to the delayed diffusion from the approach and are likely to be independent of the actual reaction. Improvement can be Smaller and more volatile groups take place, also in the sense of a generally accelerated progress of the action (also vacuum as an aid).

Where applicable, all individual features illustrated in the embodiments may be combined and / or interchanged without departing from the scope of the invention.

Claims

claims

1. A process for the preparation of functionalized acrylate polymers, characterized in that an acrylate polymer, at temperatures between 50 ° C and 350 ° C, preferably between 100 ° C and 200 ° C, optionally in the presence of a catalyst, with a functionalizing A reagent is reacted, which agent has at least one primary or secondary amino group, and wherein the amino group is reacted with an ester group of the acrylate polymer to an amide function, and wherein the reaction takes place in the absence of a solvent.

2. Method according to claim 1, characterized in that the functionalizing agent has at least one further functionality per molecule.

3. A method according to claim 1 or 2, wherein the functionalizing agent is selected from a group consisting of aliphatic or aromatic primary or secondary amines.

4. The method according to claim 1, characterized in that the functionalizing A gene gens having an amino group according to claim 3 and at least one further functional group.

5. The method according to claim 4, wherein the functional agent is selected from the group consisting of di- or polyamines.

6. Modified acrylate polymer, obtainable according to one of the preceding claims.