DE102012211908A1 - Bio-based, keto group-containing (meth) acrylates and process for their preparation - Google Patents

Abstract

The present invention relates to monomer mixtures containing bio-based (meth) acrylates containing keto groups, their production and their use, resins which crosslink at room temperature.

Description

The present invention relates to monomer mixtures containing biobased, keto-containing (meth) acrylates, their preparation and their use in room temperature curing resins. The term (meth) acrylates defines both derivatives of methacrylic acid and of acrylic acid.

Room-temperature curing resins whose crosslinking mechanism is based on reactions of carbonyl groups are widely used in the art and as coating formulations or adhesive applications, for example, in US Pat EP 0016518 . DE 4237030 or EP 2246403 described. Together, these resin systems generally have copolymers - in the more modern realizations usually aqueous, VOC-free emulsion polymers, which are composed of comonomers with pendant carbonyl function. Diacetoneacrylamide (DAAM) or acetoacetoxyethyl methacrylate (AAEMA) are most commonly used. However, these two carbonyl-functional monomers have decisive disadvantages: the former has a relatively strongly sterically hindered and therefore poorly accessible carbonyl function, while the ester group of the latter has a significant susceptibility to hydrolysis.

In addition, these monomers can be produced only with great effort. AAEMA requires diketene as a raw material that is toxic and can only be stored for a limited time. The manufacture of DAAM requires toxic acrylonitrile and the hard-to-handle oleum. Furthermore, this monomer is a solid, which generally complicates handling on a larger scale.

The object of the present invention is therefore to eliminate or at least minimize the disadvantages mentioned in the property profile of the copolymers and the difficulties in preparing the monomers. It is also an object to provide (meth) acrylates having these properties on the basis of renewable raw materials.

wobei R₁ = CH₃ oder H bedeutet. This object is achieved by providing keto group-containing (meth) acrylates of the formula (1)

where R ₁ = CH ₃ or H.

These monomers have a readily accessible carbonyl function for crosslinking and are readily accessible by reacting levulinic acid, a sustainable carbohydrate-based feedstock, with glycidyl (meth) acrylate in the presence of a quaternary ammonium salt as a catalyst, eg, according to formula (2).

They can be used for further processing, usually the polymerization in aqueous emulsion or suspension, without further work-up, the catalyst does not have to be removed.

The reaction of the glycidyl (meth) acrylate with levulinic acid is carried out in a manner known per se by combining the components in an appropriate amount, if appropriate with the aid of a solvent and a catalyst.

The catalyst is selected from the groups known per se metal salts, such as dibutyltin dilaurate, tin octoate, phosphorus compounds such as triphenylphosphine or ethyltriphenylphosphonium bromide, tert. Amines, such as dimethylaminopyridine or benzyldimethylamine or quaternary ammonium compounds. Preferred examples of the quaternary ammonium salts are tetramethylammonium chloride. Tetramethylammonium bromide, trimethyldodecylammonium chloride. Trimethylbenzylammonium. Triethylbenzylammonium chloride and the like. These compounds may be used alone or in combination of two or more. Particularly preferred is triethylbenzylammonium chloride.

The reaction is carried out during several hours of heating at temperatures in the range of 60-120 ° C, preferably in the presence of an inhibitor, or while oxygen or an oxygen-containing gas is passed through the reaction mixture to prevent polymerization. Preference is given to a batch process with the introduction of levulinic acid with successive addition of the epoxide compound.

Examples of suitable inhibitors are hydroquinones, hydroquinone ethers, such as hydroquinone monomethyl ether or di-tert-butyl catechol, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, N, N'-diphenyl-p-phenylenediamine, methylene blue or hindered phenols which are well known in the art. These compounds can be used singly or in the form of mixtures and are generally available commercially. The effect of the stabilizers is usually that they act as radical scavengers for the free radicals occurring during the polymerization. For further details on the usual specialist literature, in particular on the Römpp-Lexikon Chemistry; Publisher: J. Falbe, M. Regitz; Stuttgart, New York; 10th edition (1996) ; Reference "Antioxidants" and cited references cited here. In particular, phenols are preferably used as the polymerization inhibitor. Particular advantages can be achieved when using hydroquinone monomethyl ether.

Based on the weight of the entire reaction mixture, the proportion of inhibitors, individually or as a mixture, can generally be 0.01-0.5% by weight.

The use of the monomers according to the invention for the preparation of copolymers for use in the room temperature crosslinking resins can be carried out in a conventional manner. In principle, any form of free-radically initiated polymerization process, e.g. in emulsion, mini-emulsion, solution, suspension, mini-suspension or substance suitable, wherein the respective polymerization temperature depends on the disintegration characteristics of the particular polymerization initiator used. The aqueous emulsion polymerization is preferred.

The initiators are used in conventional amounts, for example in amounts of 0.01 to 10 wt .-%, preferably 0.1 to 5 wt .-%, based on the monomers to be polymerized. As initiators, it is possible to use all compounds which decompose into free radicals under the polymerization conditions, for example peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and the so-called redox initiators. In some cases, it is advantageous to use mixtures of different initiators, for example mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate. Mixtures of hydrogen peroxide and sodium peroxodisulfate can be used in any proportion. Suitable organic peroxides are, for example, acetylacetone peroxide, methyl ethyl ketone peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-amyl perpivalate, tert-butyl perpivalate, tert-butyl perohexanoate, tert-butyl perisobutyrate, tert-butyl per-2-ethylhexanoate, tert. Butyl perisononanoate, tert-butyl permaleate, tert-butyl perbenzoate, di- (2-ethylhexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate, dimyristil peroxydicarbonate, diacetyl peroxydicarbonate, allyl perester, cumyl peroxyneodecanoate, tert-butyl per-3 , 5,5-trimethylhexanoate, acetylcyclohexylsulfonyl peroxide, dilauryl peroxide, dibenzoyl peroxide and tert-amylpemeodecanoate. Preferred initiators are azo compounds, for example 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile).

Suitable non-crosslinking functional comonomers for use in combination with the monomers of the present invention are vinyl monomers such as 1,3-butadiene, isoprene, styrene, substituted styrenes, divinylbenzene, heterocyclic vinyl compounds or vinyl halides; Vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate or vinyl laurate; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, vinyl 2-methoxyethyl ether, or vinyl 2-chloroethyl ether; (Meth) acrylic esters with C ₁ -C ₂₄ -alcohols, for example methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isopropyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, n- or isopropyl (meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, tert-amyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, Octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate; (Meth) acrylic esters of ether alcohols such as ethylene glycol monomethyl ether (meth) acrylate, and di (meth) acrylates of C ₁ -C ₆ diols such as 1,6-hexanediol di (meth) acrylate or (meth) acrylic acid or other, vinylic unsaturated carboxylic acids, carboxylic acid amides or nitriles.

Suitable crosslinking-functional comonomers for use in combination with the novel monomers in self-crosslinking resins are comonomers whose functional side group can react with the novel keto-containing monomers, such as amines, hydrazines or oxime-blocked isocyanates. Such comoners are eg in EP 2246403 or DE 4237030 described.

The monomers of the invention are also suitable for use in resins in which the crosslinking function is not incorporated in the polymer component itself, but a separate crosslinking agent is added. Typically, amines, diamines, triamines, hydroxylamines, oximes, oxime ethers, oxyamines, dihydrazines, dihydrazides, trihydrazides or polyhydrazides are used here, for example. Other suitable crosslinkers are, for example, in WO 2006/086322 described.

The amount used of the novel monomers in the copolymers is 0.2-35 wt .-%, preferably 0.5-20 wt .-% and particularly preferably 1-10%. The amount of each of the crosslinking active comonomers is tuned to molar. This also applies to the use of the separate networked.

The following examples are intended to illustrate but not limit the invention in any way.

Examples

example 1

Preparation of levulinic acid methacrylate (KEMA).

81.3 g (0.70 mol) of levulinic acid, 0.028 g of hydroquinone monomethyl ether as polymerization inhibitor and 0.86 g of benzyltriethylammonium chloride (catalyst) are weighed into a 250 ml five-necked round-bottomed flask containing saber stirrer with stirring sleeve and stirrer motor, thermometer, dropping funnel, reflux condenser, air inlet tube and temperature-controlled oil bath , The solution consisting of levulinic acid, stabilizer and catalyst is heated to 75 ° C. with stirring and introduction of air. At this temperature, 99.5 g (0.70 mol) of glycidyl methacrylate are added dropwise within 30 min. Thereafter, the solution is stirred for 10 h at 85 ° C. Allow to cool and analyze the product by gas chromatography. GC analysis shows 73.8 area% levulinic acid methacrylate.

Example 2

Preparation of KEMA Copolymers by Emulsion Polymerization

Apparatus: Witt pot (2L) with stainless steel blade stirrer, stirrer motor, reflux condenser, thermocouple, water bath (with heating, cooling and circulation pump), temperature controller, feed vessel, piston pump, temperature recorder. Procedure: 12 g emulsifier (Disponil FES32, Cognis) are dissolved in 359 ml dem. Water, 400 g monomer mixture (4% by weight KEMA, 50% by weight methyl methacrylate (MMA), 45% by weight butyl acrylate and 1% by weight. % Methacrylic acid) and 1.2 g of initiator (ammonium peroxodisulfate, Merck) were added and then emulsified for 3 min by means of Ultra-Turrax at 4000 rpm. The emulsion is transferred to the feed vessel. The dosing speed of the piston pump is set by test intervals of 1 min each so that the total dosing time is 4 h. The apparatus is charged with 230 ml of deionized water and 0.3 g of emulsifier and heated to 80 ° C. with stirring. The polymerization is started by starting the interval: addition of the aqueous initiator solution (0.3 g of APS in 10 g of water), 5 min break, 3 min of emulsion addition, 4 min break, residual feed over 3:57 h. After the end of the feed, an after-reaction is carried out for 1 h at 80.degree. The mixture is then cooled to room temperature, the finished dispersion is filtered through a fast sieve (mesh size 125 μm) and adjusted to pH 9 with 25% strength ammonia solution.

Comparative Example 1

Preparation of AAEMA Copolymers by Emulsion Polymerization

The preparation was carried out as described in Example 2, using only 4% by weight AAEMA (Eastman) instead of 4% by weight KEMA. The final dispersion had a pH of 4.2.

Comparative Example 2

Preparation of DAAM Copolymers by Emulsion Polymerization

The preparation was carried out as described in Example 2, using only 4% by weight of DAAM (Aldrich) instead of 4% by weight of KEMA. The final dispersion had a pH of 4.6.

Networking

In each case 100 g of the acidic or alkaline dispersions were weighed out into 125 ml wide-mouth bottles and, while stirring (magnetic stirrer), treated dropwise with aqueous adipic dihydrazide solution (Fluka, 15% solution) (equimolar, in each case based on the incorporation amount of KEMA, AAEMA or DAAM). , The mixtures were stirred for 2 h and then measured for pendulum hardness, gloss and water absorption on wood (see Table 1). Tab. 1: Measurements Example 2 Comparative Example 1 Comparative Example 2 KEMA AAEMA DAAM pendulum hardness 1d 79,8s 89,6s 44,8s 7d 74,6s 77,0s 46,2s 14d 81,9s 60,7s 51,8s 21d 80,5s 77,0s 55,3s 28d 78,8s 67,2s 62,3s shine 20 ° 101 92.0 52.9 60 ° 129 123 80.9 85 ° 97.0 89.9 78.3 Water intake wood 1h 3.63% 3.23% 4.90% 2h 5.46% 4.79% 8.26% 3h 6.09% 5.82% 11.45% 4h 7.81% 6.95% 13.98% 5h 8.89% 7.81% 16.04% 6h 9.55% 8.59% 18.61% 7h 10.52% 9.26% 21.50% 8h 11.10% 10.07% 22.73% 24 hours 19.68% 18.55% 37.58%

measurement methods

Determination of pendulum hardness according to König (DIN 53157)

Each two glass plates (9 × 12 cm) are coated by means of Filmziehrahmen with dispersion film (layer thickness wet: 200 microns). After different drying times, the pendulum hardness is determined. For testing, the coated glass plate is placed in the tester, the pendulum placed on the film surface, deflected to 6 ° and triggered. The number of pendulum oscillations is measured between 6 ° (deflection at the beginning of the measurement) and 3 ° deflection. In each case a double determination is carried out and the mean value is formed. The pendulum hardness is given in s according to DIN 53157 (one oscillation corresponds to 1.4 s).

Gloss (DIN 67530)

Black-painted metal panels (Metopac, Leneta) are coated with a dispersion film by means of a film-drawing frame (layer thickness wet: 200 μm). After 7 d drying time at RT, the reflectometer values at 20 °, 60 ° and 85 ° are determined by means of gloss meter (Picogloss 503, Erichsen). 5-fold determinations are carried out, the lowest and the highest value are canceled and the average value is calculated from the remaining three values.

Water intake on wood

Test specimens of untreated solid pine wood (dimensions: 45-50 mm × 45-50 mm × 17 mm) are coated on the upper side and the side surfaces with dispersion film, wherein the specimen by means of a flat bristle brush quickly twice in Holzmaserrichtung and the cut edges three times with dispersion coated become. The specimens are weighed after a drying time of 7 d and placed with the coated side down in demineralised water. For more than eight hours, the specimens are taken out every hour, dabbed, weighed and returned to demineralised water, a final weighing takes place after 24 h. The mass of the absorbed water is related to the mass of the dry test specimen (water absorption in%).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0016518 [0002]
• DE 4237030 [0002, 0016]
• EP 2246403 [0002, 0016]
• WO 2006/086322 [0017]

Cited non-patent literature

• Römpp-Lexikon Chemistry; Publisher: J. Falbe, M. Regitz; Stuttgart, New York; 10 th edition (1996) [0011]

Claims (5)

Keto group-containing (meth) acrylates of the formula (1)

where R ₁ = CH ₃ or H. A process for preparing a (meth) acrylate of the formula (1), which comprises reacting glycidyl (meth) acrylate with levulinic acid in the presence of a catalyst. A method according to claim 2, characterized in that the catalyst is an ammonium salt.  Use of a (meth) acrylate of the formula (1) for the preparation of copolymers for room temperature crosslinking with carbonyl group-reactive crosslinkers.  Use of a (meth) acrylate of the formula (1) according to claim 4, wherein the crosslinkers have amine, hydrazine or hydrazide groups.