CH682490A5 - Prepolymer curable composition comprising the same and use of the assets. - Google Patents

Description

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description

The invention relates to prepolymers based on bifunctional polyether derivatives which contain ureide groups and polymerizable, ethylenically unsaturated groups. The invention also relates to curable compositions which contain these prepolymers and which are preferably light-curable and solvent-free. The curable compositions are preferably used as adhesives, sealing compounds or investment compounds.

The use of new materials of different types in industrial production increasingly requires the use of adhesives and sealants in the connection of parts consisting of these materials. However, the advantages of joining technology are often diminished by inadequate material properties of the polymers used as adhesives and sealants. For example, particularly critical the storage stability of the adhesives as well as the weathering resistance and the long-term behavior of the connecting material in the adhesive joint, in particular plastics with other materials such as e.g. Metal, glass, ceramics and the like are often insufficiently bonded in terms of storage stability, weathering resistance and long-term behavior. For example, there has long been an unsatisfied need for an adhesive with which polycarbonates can be permanently bonded to other materials in a satisfactory manner in every respect.

DE-OS 2 324 822 discloses photopolymerizable polymers which can be obtained by reacting an organic di- or polyisocyanate with an acrylate or methacrylate, the ester component of which has a hydroxyl or amino group. (Poly) addition of the acrylate to diisocyanate groups gives rise to oligomers which have urethane and / or ureide groups. These known compounds can be used to produce free-radically curable compositions by adding polymerization initiators, accelerators, inhibitors, diluents, thickeners, other viscosity-setting agents, plasticizers and the like, which are used as UV-curable adhesives. Because of their sensitivity to light, these known adhesives only have an insufficient storage stability even when stored carefully in the dark. The very fast curing under UV radiation leads to hard and brittle polymers that do not withstand the occurring thermal cycling voltages to a sufficient extent when bonding different types of materials. In addition, due to the pronounced oxygen inhibition (trapping free radicals by oxygen molecules in the air), undesired lubrication layers remain on the surface of the cured polymers.

DE-AS 1 745 063 describes rapidly hardening imaging compositions which are made from the same or very similar monomers as are known from DE-OS 2 324 822, by poly (addition) of hydroxy and amino functional groups, under anaerobic conditions Acrylates on poly-isocyanates are available. In particular if they are processed in thicker layers, these sealing compounds are often too hard after curing and therefore brittle and do not adhere sufficiently well to the substrates to be bonded or sealed.

DE-OS 2 610 423 describes a curable adhesive and sealant made from a polymerizable product, which can be obtained by reacting a

(a) poly (alkylene) ether polyol, preferably a glycol, with

(b) either

(i) at least one molar equivalent of a reaction product from: at least one molar equivalent of an aromatic or cycloaliphatic polyisocyanate and an aromatic or cycloaliphatic polyol or polyamine or

(ii) at least one molar equivalent of an aromatic or cycloaliphatic polyisocyanate, the product of (a) and (b) (i) or of (a) and (b) (ii) subsequently having at least one molar equivalent of an acrylic or methacrylic acid hydroxyalkyl or amino alkyl ester has been formed.

US Pat. No. 4,133,723 describes a coating composition which consists of at least one unsaturated urethane resin which is obtained by reacting at least one polyalkylene oxide polyol and organic isocyanates.

The prepolymers made from polyols and in particular poly (alkylene) ether glycols and organic isocyanates, in particular aromatic and / or cycloaliphatic diisocyanates, which are produced according to both proposals, have in common that they produce relatively brittle compositions which also tend to discolour.

Furthermore, by using the prepolymers produced in accordance with these proposals in adhesives and sealants, only relatively low tensile shear strengths of the bonds and low adhesive strengths on polycarbonate substrates are achieved.

The invention has for its object to provide prepolymers and curable compositions prepared therefrom, which allow the production of solid and permanent bonds and have improved flexibility, elasticity and extensibility of the polymers in the cured state, improved thermal shock resistance and resistance to other mechanical stresses. The polymerizable compositions should also be able to be used as sealing material, should be able to be cured quickly and gently, and should polymerize as shrink-free as possible.

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Ren. In the hardened state, the masses should be as inert as possible to solvents in order to enable permanent non-swelling seals or bonds. The substrates to be bonded to the compositions should not be negatively influenced either chemically or by the curing mechanism. Finally, the invention has for its object to provide an effective means for the permanent joining and bonding of polycarbonates.

This object is achieved according to the invention by the prepolymers according to one of claims 1 to 5, by the curable compositions according to one of claims 6 to 9 and by the use according to claim 10.

The prepolymers based on bifunctional polyether derivatives according to the invention are obtainable by reaction

(A) a polyether diamine of the formula

H-X1-P-X1-H (I)

wherein Xi is NH or NR and R is an alkyl group with 1 to 4 carbon atoms and the polyether P at least partially consists of polytetrahydrofuran units,

(B) with a diisocyanate of the formula 0 = C = N-Al-N = C = 0 (II)

in which Ai is an optionally substituted hydrocarbon radical having 2 to 30 carbon atoms,

(C) and with a monomeric, hydroxy and / or amino functional derivative of acrylic and / or methacrylic acid of the formula

O R

1 "1

H-X2-R -0-C-C = CH2 (III)

wherein

X2 represents an oxygen atom, NH or NR and R is an alkyl group with 1 to 4 C atoms, R1 is a C2-C4 alkylene group and R2 is H or CH3.

Prepolymers which are obtainable by reacting components (A), (B), (C) in the ratio A: B: C = 1: 2: 2 are preferred according to the invention. These preferred prepolymers correspond to the formula (V):

O H

" 1

H O

1 H

O R

11 1

Pt-X1-C-N-A1-N-C-X2-R-0-C-C = CH2] 2

(V)

wherein P, Ai, Xi, X2, R1 and R2 have the meanings given above.

According to the invention, a polyether diamine with an average molecular weight of 1000 to 20,000 is preferably used as component (A). The bifunctional polyether diamine can be a homopolymer, a block copolymer or a copolymer with an irregular sequence of the chain building blocks. In any case, the bifunctional polyether derivative must at least partially consist of polytetrahydrofuran units. It is preferably a polytetrahydrofuran (PTHF) homopolymer with 4 to 200, particularly preferably with 10 to 100, [- (CH2) 4-0 -] units (average chain length in the oligomer or polymer molecule).

If a bifunctional block copolymer is used as component (A), it is preferably one having structural elements of the formula t (CH2) 4O * JÉR3O * Z (VI)

wherein

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R3 is an alkylene or isoalkylene radical each having 2 to 4 carbon atoms and y, z, which may be the same or different, each represent an integer from 2 to 100, preferably from 5 to 50.

Finally, a copolymer of tetrahydrofuran and an alkylene oxide with an irregular distribution of [(CH2) 40] and [R3Oj units can be used as component (A), where R3 has the meanings mentioned above and preferably an ethylene, propylene or butylene -Rest is.

The definitions given for component (A) with the formula (I) include bifunctionally-substituted polytetrahydrofuran, in which the two amino groups (-XrH) are not bonded directly to tetramethylene oxide units of the polyether, but rather to a further alkylene oxide group (-R30-) with which the ends of (Poiy) tetramethylene oxide chains have been previously modified.

Suitable commercial products as component (A) are e.g. Poly-THF diamines such as PTHF diamine 5200 and bis (3-aminopropyl) PTHF diamine 2100 from BASF.

As component (B) such diisocyanates of the formula (II) are preferably used, in which Ai is an aliphatic, cycioaliphatic or aromatic or a mixed aiiphatic-cycloaliphatic or a mixed aromatic-aliphatic hydrocarbon radical, optionally with alkyl, alkoxy and Carboxyl groups each having 3 to 6 carbon atoms and / or with halogen atoms (F, CI, Br and I) can be substituted. Diisocyanates of the formula (II) are particularly preferably used, in which Ai is an optionally substituted alkyl radical having 1 to 12 carbon atoms.

Diisocyanates of the formula (II) which are suitable for the preparation of the prepolymers according to the invention are, for example, ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, cyclobutane-1,3-diisocyanate, cyciohexane-1,3- and -1,4-diisocyanate, tolylene diisocyanate , 4,4'-diphenyl diisocyanate, 4,4'-diphenylene methane diisocyanate, p-phenylene diisocyanate, trimethylene diisocyanate, nonamethylene diisocyanate, octamethylene diisocyanate, 2-chloropropane diisocyanate, isophorone diisocyanate, 3-heptene diisocyanate, tetrachlorophenylene diisocyanate di-1,4-diisocyanate, 1,5-trans, phenyl diisocyanate -Naphthalene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,4-xyyiene diisocyanate, 3,3-dimethylbiphenylene diisocyanate, bis- (isocyanato) tricyclo [5.2.1.02.6] -decane. Hexamethylene diisocyanate and trimethylhexamethylene diisocyanate are particularly preferably used.

Hydroxyl group-containing and amino group-containing derivatives of acrylic acid and methacrylic acid, which are suitable as component (C) for the preparation of the prepolymers according to the invention, are, for example, hydroxyethyl acrylate, hydroxyethyl methacrylate, aminoethyl methacrylate, 3-hydroxypropyl methacrylate, aminopropyl methacrylate, hydroxyhexylacrylate, tert-butylamethylethylhydroxyethyl acrylate.

In the preparation of the prepolymers according to the invention, the components (A), (B) and (C) are reacted at -10 to + 100 ° C., preferably at 0 to 20 ° C. The reaction can be carried out in a suitable solvent, for example in dichloromethane, but is preferably carried out without the addition of a special solvent. The reaction can also be carried out using catalysts, for example organic tin compounds such as dibutyltin diiaurate, but can also be carried out without the addition of a catalyst.

The prepolymers according to the invention contain at least 2 to 10 ureide groups, preferably 2 to 6. A number of 2 ureide groups per molecule has proven to be particularly advantageous.

The ratio between the molecular weight and the number of carbonyl groups adjacent to a nitrogen atom is preferably 100 to 1000 in the prepolymer molecule according to the invention.

The curable compositions which can be prepared from the prepolymers according to the invention comprise, in addition to at least one of these prepolymers, at least one diluent monomer which can be copolymerized with the prepolymer and which serves both for setting the desired viscosity and for modifying the chain length of the polymers, and the curable composition also contains a hardener system for either radical polymerisation or anaerobic hardening or for hardening induced by actinic radiation or by light as well as optionally other additives such as adhesion improvers, polymerization inhibitors and other customary auxiliaries and additives, including fillers, pigments, odorous substances and the like.

The copolymerizable diluent monomers selected from the group of vinyl monomers and hydroxy-functional derivatives of acrylic acid and methacrylic acid, for example hydroxyethyl acrylate or hydroxypropyl methacrylate, are preferably selected. Compounds which can also be used simultaneously as component (C) for the preparation of the prepolymers according to the invention can thus be used as dilution monomers.

This results in the advantage that components (A), (B) and (C) can also be reacted with one another in the preparation of the prepolymers in such a way that component (C) is added in excess, so that the Excess portion of the functional derivative of acrylic acid or methacrylic acid is at least partially polymerized into the resulting prepolymer and thus serves to extend the chain, but at least partially remains unchanged in the reaction mixture and thus serves as a diluent monomer. When components (A), (B) and (C) are reacted, the vinyl monomer or acrylate / methacrylate monomer remaining in addition to the resulting prepolymer does not need to be separated off in the preparation of the prepolymer according to the invention; rather, the reaction mixture, as it is, can be used to prepare the curable compositions according to the invention

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used and further processed.

Depending on the type of curing mechanism desired, a curing system is added to the curable compositions according to the invention.

If curing is to be carried out by radical polymerization, the curing system consists of suitable initiators, if appropriate in conjunction with accelerators.

Suitable initiators are, for example, diacyl peroxides such as dibenzoyl peroxide and di-p-chlorobenzoyl peroxide or peroxyesters such as tert-butyl peroxybenzoate or alkyl peroxides such as bis- (tert-butyl-peroxy) -buane and dicumyl peroxide or hydroperoxides such as cumene hydroperoxide, tert-butyl hydroperoxide and methyl ethyl ketone hydroperoxide.

Aromatic amines are optionally added as polymerization accelerators.

If curing is to be carried out with light in the ultraviolet and / or visible range, photoinitiators are added to the curable compositions.

Suitable photoinitiators are described for example in DE-OS 2 251 048 and 2 003 132 as well as in US Pat. Nos. 2,548,685, 2,495,987, 3,551,246 and 3,558,387 and in EP-A 0 073 413. Some of these known and suitable photoinitiators for the purposes of the invention are benzophenon and its derivatives, acyloins such as benzoin and its derivatives, anthraquinones, aromatic disulfides, vicinal diketones and their derivatives such as benzil, benzil acetals, e.g. Benziidimethylketal, camphor quinone, fluorenone as well as thioxantones, multinuclear quinones, acridines and quinoxalines; also trichloromethyl-s-triazines, 2-halomethyl-4-styryl-1,3,4-oxadiazole derivatives, trihalomethyl-substituted halo-oxazoles and the tricarbonylmethyienes heterocycles described in DE-OS 3,333,450.

In addition to the photoinitiators, reducing agents, e.g. tertiary amines can be added to accelerate the curing of the masses.

Suitable photoinitiators are also metal carbonyls such as Mo2 (CO) io, Fe (CO) 5, Re2 (CO) io, Cr (CO) 6, Co2 (CO) 8, Ni (CO) 4 and Mo (CO) 6 and derivatives thereof Carbonyls.

Preferred photoinitiators are acylphosphine oxide compounds as well as other phosphorus-containing compounds such as e.g. Dibenzoylisobutylphenylphosphine oxide, dibenzoylisopropylphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -4-n-propylphenylphosphine oxide and bis- (2,6-dichlorobenzoyl) -4-n- butylphenyl phosphine oxide.

If the compositions according to the invention are to be cured by an anaerobic curing mechanism, suitable activators such as cumene hydroperoxide and suitable accelerators such as saccharin, methyl-p-toluidine or N, N-dimethylaniline in amounts of 0.01 to 20% by weight are preferred as the curing system from 0.1 to 10% by weight, and in the presence of traces of suitable metal ions, for example Copper ions added.

The compositions according to the invention can also be cured by irradiation with actinic radiation, for example electron beams or gamma rays.

The compositions according to the invention can also contain at least one compound which acts as a polymerization inhibitor. Polymerization inhibitors prevent premature gelation of the masses and thus increase their shelf life. They are added in amounts of 0.001 to 1% by weight, preferably 0.01 to 0.5% by weight, based on the weight of the total mixture. Suitable inhibitors are, for example, phenols, phenol derivatives, preferably sterically hindered phenols, which are alkylated in the ortho and / or para position, for example toluhydroquinone, 2,6-ditert.-butyl-p-cresol and quinones or hydroquinones such as p-benzoquinone, Naphthoquinone and di-tert-butyl-p-benzoquinone.

The curable compositions according to the invention may further contain 0 to 10% by weight of an adhesion improver. Free acrylic and methacrylic acid, carboxyethyl acrylate, hexaethyl methacrylate phosphate, silanes such as methacryloxypropyl trimethoxysilane and disilazanes such as divinyl tetramethyl disilazane are suitable as adhesion improvers.

According to the invention, a preferred curable composition contains the following constituents:

20 to 85% by weight prepolymer

14.4 to 60 wt% dilution monomer

0.5 to 10 wt .-% adhesion improver

0.1 to 10 wt .-% initiator.

The curable composition according to the invention preferably has a viscosity of 100 mPa.s to 10,000 mPa.s.

The compositions according to the invention can advantageously be used as adhesives, sealing compositions or embedding compositions, but particularly advantageously as means for joining and gluing bodies or surfaces made of polycarbonate with bodies or surfaces made of polycarbonate or of other materials. After hardening, the masses have excellent adhesive strengths on different materials such as glass, metal and plastic. Surprisingly high adhesive strengths are achieved when bonding various types of substrates made of glass, polymethyl methacrylate (PMMA) and polycarbonates. Also surprising is the surprisingly high stability of the cured compositions against many chemicals.

In contrast, a corrosive behavior of the masses towards metallic or polymeric substances was not found. The bonds are permanent and show a high elasticity of the connecting material, both in thin and thick layers in the adhesive joint, which is why the masses can withstand strong mechanical stresses. The masses have excellent storage

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durability, and the curing times are extremely short. In particular in the case of photo-induced radical formation, hardening which is almost free of smear layers is found even with unusually thick layers. On the other hand, a polymerization-related shrinkage of the masses is hardly noticeable.

Without wishing to be bound by theory, it is assumed that the sum of the advantageous properties of the compositions according to the invention described is based primarily on the use of a bifunctional polyether derivative in the preparation of the prepolymers which consists wholly or partly of polytetrahydrofuran units.

The invention is further explained below using exemplary embodiments:

example 1

a) Prepoivmer

3.4 g (20 mmol) of hexamethylene diisocyanate are placed in 50 ml of dry methylene chloride in an anhydrous, nitrogen-flushed apparatus. Then, at a temperature of 0 to 5 ° C., 57.2 g (10 mmol) of PTHF diamine 5200 (found base equivalents: 2860), dissolved in a further 50 ml of methylene chloride, are added over a period of 50 minutes. After stirring for a further 90 minutes, 0.1 g of dibutyltin dilaurate is added. 24.5 g (170 mmol) of hydroxypropyl methacrylate (excess) are again added to the resulting mixture at 0 to 5 ° C. within 10 minutes. The mixture is stirred overnight at room temperature and made solvent-free in vacuo at 30 ° C. The resulting reaction product, consisting of 75% by weight of prepolymer and 25% by weight of unreacted hydroxypropyl methacrylate, is used without further workup to produce the curable composition.

b) Curable mass

18.9 g of the reaction product obtained above are added with 12.6 g hydroxypropyl methacrylate, 2.63 g methacryloxypropyltrimethoxysilane, 0.88 g acrylic acid and 0.35 g bis- (2,6-dichlorobenzoyl) -4-n-propylphenylphosphine oxide mixed with a homogeneous liquid adhesive mass. This mass has a viscosity of 3200 mPa.s (measured with a plate control viscometer) and is used for the bonds described below.

Five pressure shear strength test specimens each measuring 20 mm x 20 mm x 5 mm are washed with Isopropan, then glued with the adhesive at room temperature and with a commercially available UV lamp (DELO-Lux 03 from DELO Kunststoffchemie GmbH & Co. RG, Munich -Graefelfing) irradiated for 60 seconds. The compressive shear strengths are measured on these moldings using a universal testing device from Zwick (test speed: 10 mm / min), the following values being determined:

(The specified measured values are the average values formed from the individual measurement results.)

16.2 MPa tensile strength at 183% elongation at break is measured on five tensile test specimens with the dimensions 26 x 6 x 2 mm (shoulder stick measuring section 10x2x2 mm) (cohesive crack; withdrawal speed: 5 mm / min).

Example of comparison a) Prepoivmer

530 g (265 mmol) of polypropylene glycol-2000 (PPG-2000) are placed in a dry apparatus flushed with nitrogen, and 0.42 g of dibutyltin dilaurate are added. 89 g (530 mmol) of hexamethylene diisocyanate are added to this mixture at 40 to 50 ° C. in the course of 60 minutes, after which it is left to stand at room temperature overnight. The following day, 352.4 g (2.45 mmol) of hydroxypropyl methacrylate are again added at 40 to 50 ° C. over 20 minutes and the mixture is stirred again overnight at room temperature.

b) Curable mass

45 g of the PPG-diurethane-dimethacrylate / hydroxypropyl methacrylate mixture are mixed with 3.75 g of meth-acryloxypropyltrimethoxysilane, 1.25 g of acrylic acid and 0.5 g of bis- (2,6-dichlorobenzoyl) -4-n-propylphenyl-

Glass / glass

PMMA / PMMA

Polycarbonate / polycarbonate

20.4 MPa 17.8 MPa 7.7 MPa

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phosphine oxide mixed to a homogeneous mass. The mass has a viscosity of 3000 mPa.s (plate-cone viscometer).

As described in Example 1, pressure shear strength test specimens are bonded with this adhesive composition, the composition is hardened and the tensile strengths are determined under the same conditions as described in Example 1. The following average values resulted:

Glass / glass 11.8 MPa

PMMA / PMMA 13.1 MPa

Polycarbonate / polycarbonate 0.7 MPa

The tensile strength measured was 10.1 MPa at 192% elongation at break (cohesive crack).

As the comparison between the example according to the invention and the comparative example shows on the other hand, the adhesive compositions according to the invention, in particular when polycarbonate is being bonded, surprisingly achieve higher shear strengths than with the conventional adhesive compositions, and that at comparable high elongation at tear.

Claims (11)

1. Prepolymer based on bifunctional polyether derivatives, which is derived from: (A) a polyether diamine of the formula I H-X1-P-X1-H (I) wherein Xi is NH or NR and R is an alkyl group with 1 to 4 Is C atoms and the polyether P at least partially consists of polytetrahydrofuran units, (B) a diisocyanate of the formula II OCN-A1-NCO (II) in which Ai is an optionally substituted hydrocarbon radical having 2 to 30 C atoms, (C) and a monomeric, hydroxy and / or amino functional derivative of acrylic and / or methacrylic acid of the formula III 1 " ' H-X2-R-0-C-C = CH2 (III) wherein X2 denotes O, NH or NR and R is an alkyl group with 1 to 4 carbon atoms, R1 is a C2-C4 alkylene group and R2 is H or CH3. 2. Prepolymer according to claim 1, which is derived from components (A), (B) and (C) in the ratio A: B: C = 1: 2: 2, wherein component (A) is a polyether diamine with a average molecular weight is from 1000 to 20,000. 3. Prepolymer according to claim 1 or 2, which is derived by using as component (A) a polyether derivative of the formula I in which P is a polytetrahydrofuran homopolymer with an average chain length of 4 to 200 [(CH2) 40] units is. 4. Prepolymer according to claim 1 or 2, which is derived by using as component (A) a polyether derivative of the formula I, wherein P is a block copolymer with structural elements of the formula VI {■ (CH2) 40} ytR303-2 (VI) is what R3 is an alkylene or isoalkylene radical each having 2 to 4 carbon atoms and y, z, which may be the same or different, each represent an integer from 2 to 100. 5. Prepolymer according to claim 1 or 2, which is derived by using as component (A) a polyether derivative of the formula I, wherein P is a copolymer of tetrahydrofuran and a 7 5 10th 15 20th 25th 30th 35 40 45 50 55 CH 682 490 A5 Alkylene oxide having an irregular distribution of [(Cl-feUO] and [R30] units, where R3 has the meanings given in claim 4. 6. Curable composition comprising at least one prepolymer according to one of claims 1 to 5, at least one diluent monomer copolymerizable with the prepolymer and a hardener system. 7. Curable composition according to claim 6, characterized in that it additionally contains adhesion improvers, polymerization inhibitors and / or auxiliaries and additives. 8. Curable composition according to one of claims 6 or 7, characterized in that the copolymerizable diluent monomer is hydroxyethyl acrylate or hydroxypropyl methacrylate. 9. Curable composition according to one of claims 6 to 8, characterized in that the curing system comprises an initiator for radical polymerization, a photoinitiator or an activator and / or accelerator for anaerobic curing. 10. Curable composition according to one of claims 6 to 9, characterized by a composition of 20-85% by weight prepolymer 14.4-60 wt% dilution monomer 0.5-10 wt .-% adhesion improver and 0.1-10% by weight of initiator and a viscosity of 100 to 10,000 mPa.s. 11. Use of the curable compositions according to one of claims 6 to 10 as a means for joining and gluing bodies or surfaces, in particular made of polycarbonate with bodies or surfaces made of polycarbonate or other materials. 8th