WO2010072531A1

WO2010072531A1 - Thermal crosslinking of an organopolysiloxane compound present on a substrate by means of an aldehyde reagent

Info

Publication number: WO2010072531A1
Application number: PCT/EP2009/066318
Authority: WO
Inventors: Timo Hagemeister; Daniel Schildbach
Original assignee: Wacker Chemie Ag
Priority date: 2008-12-15
Filing date: 2009-12-03
Publication date: 2010-07-01
Also published as: DE102008054671A1

Abstract

The invention relates to a process for crosslinking an organopolysiloxane compound (S) which has at least one group of the general formula (1) ‑R¹‑NHR² (1) by means of an aldehyde reagent (A) of the general formula (2) O=CH‑R³ (2), in which a liquid (F) is prepared in a first step from organopolysiloxane compound (S) and aldehyde reagent (A), the liquid (F) is applied to a substrate in a second step and the substrate is heated in a third step, where R¹, R² and R³ are as defined in claim 1, and to the substrate containing the organopolysiloxane compound (S) crosslinked by the process using the aldehyde reagent (A).

Description

Thermal crosslinking of organopolysiloxane compound present on a substrate with aldehyde reagent

The present invention relates to a process for thermal crosslinking of substances present on a substrate

Organopolysiloxane compound having amino groups with aldehyde reagent.

Silicone or silicone-containing formulations and composites are known and are used in the form of films, coatings and coatings in large quantities for the modification and equipment of various materials and fibers. In their range of properties, silicones or silicone-containing formulations are superior to purely organic films, coatings and coatings in many respects. So leads the

Use of silicone products to a vast extent not otherwise available but usually desirable properties such as flow, gas permeability, abrasion resistance, hydrophobicity, smoothness, feel or gloss of the treated substrate.

A major problem of all coatings, but in particular of limited in their chemistry silicone coatings, is the often lack of adhesion to the respective treated substrate (so-called permanence of the coating). As a result, the coating can be removed either simply mechanically, for example by rubbing or rubbing, or by chemical stress, for example contact with various solvents and / or exposure to certain pH environments (as occur, for example, in washing processes), can solve again from the substrate. One approach to solving the problem of lack of permanence is to crosslink the individual silicone polymer chains both with each other and with the substrate to be treated, thus increasing the mechanical and chemical resistance and thus the permanence of the overall system.

Crosslinking and binding to the substrate can be effected both by non-covalent interactions and by covalent bonds.

Among the non-covalent interactions, hydrogen bonds in particular have become established. These provide, for example, in the form of urethane or urea groups within the group of thermoplastic silicone elastomers with each other for increased network density and by interaction with also hydrogen bond forming groups of the substrate (e.g., hydroxy moieties on cellulose surfaces) also for some fixation. The preparation and use of such thermoplastic silicone elastomers are described in detail, inter alia, in EP 0 606 532 A1 and EP 0 342 826 A2.

Another noncovalent crosslinking mechanism is based on acid-base interactions between Lewis basic / Lewis acidic groups of the silicone polymer with Lewis acidic / Lewis basic groups of the substrate or polymer. Examples of these are amino-functional silicone oils which, as is known, have a positive influence in particular on hydrophobicity and softness of textiles and, because of their Lewis-basic amino functionalities, have the property of being 'absorbed' onto the Lewis acidic fibers. Such silicone amine oils and their applications are described for example in EP 1555011 A. Both mechanisms have in common that their produced permanence is only temporary and inadequate and the coating can be easily removed both mechanically and chemically,

Significantly better permanence is achieved when the

Fixation of polymer and substrate or crosslinking of polymer with each other by the formation of covalent bonds occurs.

A covalent crosslinking can be carried out, for example, by the fact that the silicone polymers already in the preparation by

Use of e.g. be crosslinked trifunctional building blocks. However, the resulting polymers are thereby adversely affected in their processing properties (e.g., melt viscosities, moldability, solubility in an application aid). Also, a fixation to the substrate is usually no longer possible. A subsequent fixation / crosslinking following a successful application is therefore always useful.

Such subsequent fixation / crosslinking may be effected, for example, by the presence of alkoxysilyl groups in the silicone polymer which provide better permanence by hydrolysis and condensation with hydroxy groups of the substrate or hydroxy groups of other silicone polymers. Such alkoxysilyl-containing silicone polymers are described for example in EP 1544223 Al. However, the Si-O-C or Si-OE bonds (E = element of the substrate) which are formed in the connection to the substrate are as a rule hydrolysis-labile and therefore easy to reopen, as a result of which a good permanence, in particular in an aqueous medium, is usually not given. A formation of comparatively stable siloxane bonds Si On the other hand, O-Si as a rule again requires prior treatment of the substrate with corresponding silanes.

In paper and film coating, two systems have been established industrially based on thermally curable crosslinking mechanisms.

The historically preferred form is mechanistically based on condensation crosslinking. This type of crosslinking takes place by reaction of SiOH groups of corresponding silicone polymers, which are crosslinked with SiH-containing crosslinkers to form hydrogen, generally tin-catalyzed.

A disadvantage of these systems, in addition to the unwanted formation of hydrogen, the slow reaction time, so that usually when rolling up the coated goods, the silicone systems are not cured, which can for example lead to a back transfer of the silicone. This, in turn, has poor printability due to follow-up processes.

Mainly because of this, systems have become established in recent years which crosslink by means of a noble metal-catalyzed hydrosilylation reaction. In this case, alkylene-functionalized silicone polymers are used which vulcanize by means of noble metal (usually platinum) with an SiH-containing crosslinker without by-product formation. Within seconds, the reaction leads to a material that has hardened very well on an industrial scale. For example, reference is made here to the document US 4772515. Primarily due to the rapid rise in precious metal prices in recent years, the economic viability of this technology has been seriously challenged, leading to an intensive search for alternatives. All coating systems used are multi-component, consisting at the minimum of a silicone polymer, a crosslinker and a catalyst. In the case of noble metal-catalyzed systems, an inhibitor is also required which generates an acceptable processing time. Above all, the balance of the inhibition at room temperature with simultaneously high reactivity at elevated temperature makes such systems generally disadvantageous.

The systems can be solvent-based, solvent-free or water-based. Due to the improved environmental and safety-relevant processing, solvent-free systems are to be preferred. Water-based systems are without alternative in the direct siliconization during papermaking, since the aqueous production process requires an analogous water-based silicone system. Industrial emulsions are used.

Another crosslinking mechanism which is already known in the field of purely organic polymers concerns the so-called Λ / -methylol crosslinking. In this case, polymers are produced by copolymerization with suitable monomers which carry Λ / -Methylolamidgruppen. These are known to bind covalently to alcoholic groups even at lower temperatures in the absence of water at elevated temperature or in the presence of acidic catalysts. Likewise, they can react with each other and thus cause a crosslinking of the polymer. In both cases, covalent ether bonds are formed, which are known to be very strong and are only broken again under extreme physical or chemical stress. This effect is utilized, for example, by EP 0 143 175 A, which produces polymer dispersions via free-radical emulsion polymerization, which are over are nachvernetzbar the methylol mechanism discussed above.

Although Λ / -methylol groups can in principle be prepared by reacting amines units with formaldehyde, as a rule, however, the reaction leads to polymeric condensation products, so that polymeric networks ultimately result via imine intermediates. This reaction of amines with formaldehyde has already been described: US Pat. No. 3,461,100 describes condensation products of aldehydes and primary diamines and monoamines. The resulting high polymer condensation products are discussed as protective coatings. DE 10047643 A1 describes polymeric condensation products of aldehydes and silicon amines, which are, however, exclusively high polymer and highly crosslinked. In both documents, the product is already high polymer after implementation. It is thus no longer a reactive form, as it is the monoaddition product of a formaldehyde molecule to an amine, and is therefore no longer available for subsequent reactions on substrates or post-crosslinking reactions with each other.

In contrast, stabilized silicone emulsions or stabilized silicone solutions containing Λ / -methylolated structural units are basically capable of post-crosslinking in the sense described above.

Thus, US Pat. No. 3,433,536 A describes the Λ / methylolation of terminal and lateral amidoalkyl-polysiloxanes by treating them with aqueous formaldehyde solution in the presence of methanol, thereby producing both the corresponding Λ / -methylolamidoalkyl-polysiloxanes and the corresponding Λ / -methylol-methyl ethers to be obtained. Generally, such amide However, based Λ / -methylols and especially their ethers often have significantly reduced reactivities in the subsequent crosslinking and / or substrate fixation in comparison with N-methylols derived from corresponding amines, carbamates or ureas.

The invention provides a process for crosslinking organopolysiloxane compound (S) which contains at least one group of the general formula (1)

-R ¹ -NHR ² : D

having aldehyde reagent (A) of general formula (2)

O = CH-R ³ (2),

in which a liquid (F) is prepared in a first step with organopolysiloxane compound (S) and aldehyde reagent (A), in a second step the liquid (F) is applied to a substrate and in a third step the substrate is heated,

R is a divalent hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S- or -NR groups and may be substituted by -CN or -halogen;

2

R is a hydrogen atom, a hydrocarbon radical having 1 to 20

4 5 6

C atoms, a - (CO) -OR- group or a - (CO) -NR R- group, whereby the carbon chain by non-adjacent - (CO), -0-, -S- or -NR groups may be interrupted and substituted with -CN or -halogen;

3

R is a hydrogen atom, a hydrocarbon radical having 1 to 20

C atoms, the carbon chain is not

Q adjacent (CO), -0-, -S- or -NR groups may be interrupted and substituted with -CN or -halogen;

4

R is a hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S or NR groups and may be substituted by -CN or -halogen;

R is a hydrogen atom, a hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S- or -NR groups and may be substituted by -CN or -halogen as well as with

6 R may be covalently linked;

6

R is a hydrogen atom, a hydrocarbon radical having 1 to 20

C atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S- or -NR groups and substituted with -CN or -halogen, and may be covalently linked to R;

R is a hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain by non-adjacent - (CO) -, -0-, -

Q

S- or -NR groups may be interrupted and substituted with -CN or -halogen; and

8 R is a hydrocarbon radical having 1 to 20 C atoms;

2 with the proviso that either R is a hydrogen atom or

1 2 at least one of the radicals R or R in direct Neighboring to its shared nitrogen atom carries a - (C = O) group.

The process allows easy and rapid crosslinking on the substrate without the use of a noble metal catalyst.

The process is suitable both for impregnation and for coating with organopolysiloxane compound (S).

The organopolysiloxane compound (S) may already partially react with the aldehyde reagent (A) in the liquid (F), but the crosslinking reaction occurs on the coated or impregnated substrate.

As aldehyde reagents (A) can be used, e.g. monomeric forms of formaldehyde, such as formaldehyde gas and aqueous or organic solutions of aldehydes, as well as formaldehyde in condensed form such as paraformaldehyde, trioxane, or other aldehyde condensates. However, the aldehyde can also be present in latent form and first released in situ during the thermal crosslinking in the third step. All aldehyde-releasing agents are suitable for this purpose.

Also, an aldehyde derivative such as glyoxal can be used.

R is preferably a hydrogen atom or

Alkyl or aryl radicals each having 1 to 10 carbon atoms, more preferably a methyl radical or a hydrogen atom. Preferably, R is a divalent alkyl group

, Cycloalkyl-alkenyl, aryl or arylalkyl radical, in particular alkyl radical having in each case 1 to 6 C atoms, particularly preferably

CH ₂ - and - (CH ₂ ) 3-.

2 R is preferably a hydrogen atom or an alkyl, cycloalkyl, alkenyl, aryl or arylalkyl radical

₄ having 1 to 20 C atoms, a - (CO) -OR group or a - (CO) -

5 6

NR R group, more preferably around the hydrogen atom.

₄₄

R is preferably an alkyl, cycloalkyl, alkenyl, aryl or arylalkyl radical, in particular alkyl radical having 1 to 6 C atoms, particularly preferably the methyl radical.

R and / or R are preferably hydrogen atoms or alkyl, cycloalkyl, alkenyl, aryl or arylalkyl radicals, in particular alkyl radicals each having 1 to 6 C atoms, more preferably the hydrogen atom.

R is preferably alkyl, cycloalkyl,

Alkenyl, aryl or arylalkyl radicals, in particular alkyl radical having 1 to 6 C atoms, particularly preferably the methyl radical.

8th

R is preferably an alkyl, cycloalkyl, alkenyl, aryl or arylalkyl radical, in particular an alkyl radical having 1 to 6 C atoms, particularly preferably a methyl radical.

The organopolysiloxane compound (S) used preferably contains units of the general formula (3)

9 R _a AbSi0 (4- _a _b / 2)

in which 9

R is a hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S or -NR groups and may optionally be substituted by -CN or -halogen; R has the above meanings, a is 0, 1, 2 or 3, b is 0, 1, 2 or 3 and

A represents a group of the general formula (1), with the proviso that the sum a + b is less than or equal to 3 and the organopolysiloxane compound (S) has at least one unit of the general formula (3) with b different zero.

9

R is preferably alkyl, cycloalkyl,

Alkenyl, aryl or arylalkyl radicals, preferably alkyl or aryl radicals each having 1 to 6 C atoms, more preferably the methyl, ethyl, vinyl or phenyl radical. a is preferably 2 or 1 and b is preferably 0 or 1.

Halogen radicals in the context of the present invention are preferably fluorine, chlorine, bromine.

The organopolysiloxane compound (S) comprises both polymeric, oligomeric and dimeric organopolysiloxane compounds.

The viscosity of the organopolysiloxane compounds (S) is preferably at least 50, more preferably at least 100 mPa. s and preferably at most 5000, more preferably at most 1500 mPa.s, each at 25 ° C. The organopolysiloxane compounds (S) used are preferably essentially linear polysiloxanes having terminal and / or pendant monovalent radicals A and / or chain-containing bivalent radicals A, where A has the abovementioned meaning. In the case of the substantially linear polysiloxanes, preferably at most 5%, in particular at most 1%, of the siloxane units are branching units.

Particularly preferred are the ones having

Organopolysiloxane compounds (S) to those of the general formula (4)

AeR ⁹ ₃ -eSi0- (SiR ⁹ ₂ O) _m - ⁽⁹ siar Q) _n -SiR ⁹ ₃ - _e Ae (4)

in which

9

A and R have the meanings given above; e is 0 or 1; m is 0 or an integer of 1 to 200; n is 0 or an integer of 1 to 200, and m + n is 0 or an integer of 1 to 400; with the proviso that at least one radical A is present per molecule.

Preferably, in the general formula (4), the individual

9 9

Units (SiR 2θ) _m and (SiAR O) _n in the molecule statistically distributed. m + n is preferably at least 5, more preferably at least i, and preferably at most 500, most preferably at most 250. 9

The ratio of the groups A: R is preferably at least 1: 10,000, in particular at least 1: 1000 and preferably at most 1: 5, in particular at most 1: 30.

Crosslinking of the organopolysiloxane compound (S) with the aldehyde reagent (A) gives rise to crosslinking units of the

1 2 3 2 1 general formula -R-NR-CHR-NR-R -.

Depending on the speed of the crosslinking reaction, essentially due to the reactivity of the

Organopolysiloxane compound (S), it may also be advantageous that liquid (F) contains a catalyst for the crosslinking reaction. In principle, all Lewis and Bronsted acids are suitable as catalyst. These can be added directly to the silicone or applied as a separate component.

When the liquid (F) is a solution of aldehyde reagent (A) in organopolysiloxane compound (S), a solubilizer which is inert to organopolysiloxane compound (S) and aldehyde reagent (A) is preferably added in their preparation. Preferred solubilizers here are ethers, such as tetrahydrofuran and dioxane, hydrocarbons, such as toluene and xylene, chlorinated hydrocarbons, ketones, such as acetone and methyl ethyl ketone and esters, and mixtures thereof.

Solubilizers having a boiling point or boiling range of up to 120 ° C. at 0.1 MPa are preferred.

The liquid (F) is preferably a solution or a

Dispersion, in particular emulsion or suspension, each containing the organopolysiloxane compound (S) and aldehyde reagent (A). If the liquid (F) is an emulsion or suspension, its preparation with aldehyde reagent (A) is carried out by methods familiar to the person skilled in the art. In preparing the emulsion or suspension, organopolysiloxane compound (S) and aldehyde reagent (A) are preferably emulsified or suspended in a solvent inert to organopolysiloxane compound (S) and aldehyde reagent (A). Preferably, organopolysiloxane compound (S) is first emulsified or suspended and then the aldehyde reagent (A) is metered in. As the solvent, the abovementioned solubilizers and water are preferred.

Based on all NH units in the groups of general

Formula (1) are used for liquids (F) which are an emulsion or suspension or solution, preferably at least 0.3, in particular at least 0.7, aldehyde groups of the general formula (2). Based on all NH units in the groups of general

Formula (1) are used for liquids (F) which are an emulsion or suspension or solution, preferably at most 5, in particular at most 1.3 aldehyde groups of the general formula (2).

Preferably, the liquids (F), especially those which are a solution, stabilizers are added, which prevent the premature crosslinking.

As stabilizers are preferred aliphatic alcohols having 1 to 10 carbon atoms, preferably having a boiling point or boiling range of up to 150 ° C at 0.1 MPa, such as methanol, ethanol, isopropanol and n-butanol. The substrates impregnated or coated with the crosslinked organopolysiloxane compound (S), preferably papers and films, can be used for example for all classical release applications. By way of example, label applications, baking paper, medical sector, adhesive tapes, hygiene and graphic area are to be mentioned.

The substrates impregnated or coated with the crosslinked organopolysiloxane compound (S) may, for example, also be textiles and leather.

If paper is to be coated in the process, the liquid (F) can already be applied to the still wet paper directly after the paper making process.

The substrates impregnated or coated with the organopolysiloxane compound (S) may also be finely divided, e.g. Powder or granules, and be connected by the organopolysiloxane compound (S) as a binder to a shaped body.

In the third step, the substrate is preferably heated to at least 80 ° C, in particular at least 100 ° C and preferably at most 180 ° C. The heating preferably lasts at least 10 seconds, in particular at least 30 seconds and preferably at most 10 minutes.

The invention also provides the substrate containing the organopolysiloxane compound (S) crosslinked by the process with aldehyde reagent (A).

Examples Unless otherwise indicated, all amounts and percentages are by weight, all pressures are 0.10 MPa (abs.) And all temperatures are 20 ° C.

1. Preparation of silicone emulsions

From the (aminoalkyl) polydimethylsiloxane 1 (see Figure 1 & Table 1), a suitable emulsifier (solution in water) and demineralized water according to the common prior art known in the art using a Hochleistungs- dispersing (eg Ika Ultra-Turrax ^® ) made an oil-in-water emulsion. With gentle stirring, an aqueous solution of formaldehyde (37%) is then added to the emulsion. It was then determined the droplet size.

Figure 1: (Aminoalkyl) polydimethylsiloxane 1

Table 1: Emulsion of (aminoalkyl) polydimethylsiloxane 1

2. Preparation of silicone solutions

2.1 Solvent-containing, stabilized

6, 0 g of (aminoalkyl) polydimethylsiloxane 1 are dissolved in 4.0 g of THF and treated with 6.0 g of n-butanol. To this is added, with continuous stirring, 0.23 g of aqueous solution of formaldehyde (37%) in 2.0 g of THF. The result at 25 ° C for several days storage-stable, homogeneous silicone solution.

2.2 Solvent free

2.74 g of (aminoalkyl) polydimethylsiloxane 1 are mixed with stirring with 0.54 g of octanal. The result at 25 ° C for several hours storage-stable, slightly cloudy silicone solution.

3. Application of silicone emulsions

Emulsions from example 1 are applied with a 20 μm doctor blade to a glassine paper substrate (see Table 2). Subsequently, the coated papers are cured at 150 ° C for 120 s (1.1) or 240 s (1.2) in an oven and freed from water. The resulting siliconized papers are tested according to standard FINAT methods (see Table 2). Table 2: Application test of silicone emulsions on glassine paper Silca Classic (Ahlstrom company)

4. Application of silicone solutions

4.1 paper coating

The solutions of Example 2 are coated with a 20 μm doctor blade on a glassine paper substrate (see Table 3). Subsequently, the coated paper is cured for 2 min at 150 ° C in an oven and freed from the volatile components. The resulting siliconized papers are tested according to standard FINAT methods (see Table 3).

Table 3: Application test of silicone solutions on glassine paper Silca Classic (Ahlstrom company)

4.2 Film coating The silicone solution from Example 2.1 is applied using a 20 μm doctor blade to various corona-pretreated film substrate types (see Table 4). Subsequently, the coated films are cured for 30 s at 95 ° C in an oven and freed of the volatile components. The resulting siliconized films are tested according to standard FINAT methods (see Table 4).

Table 4: Application test of the silicone solutions on films

Claims

claims

1. A method for crosslinking organopolysiloxane compound (S) which has at least one group of the general formula (1)

-R ¹ -NHR ² (1)

having aldehyde reagent (A) of general formula (2)

O = CH-R- (2),

in the first step with

Organopolysiloxane compound (S) and aldehyde reagent (A) a liquid (F) is prepared, in a second step, the liquid (F) is applied to a substrate and in a third step, the substrate is heated, wherein

R is a divalent hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -O-, -S- or -NR groups and may be substituted by -CN or -halogen;

2

R is a hydrogen atom, a hydrocarbon radical having 1 to 20

4 5 6

C atoms, a - (CO) -OR group or a - (CO) -NR R group, wherein the carbon chain by non-adjacent - (CO) -, -0-, -S- or -NR groups may be interrupted and substituted with -CN or -halogens;

3

R is a hydrogen atom, a hydrocarbon radical having 1 to 20

C atoms, the carbon chain is not 8 adjacent - (CO), -0-, -S- or -NR groups may be interrupted and substituted with -CN or -halogen;

₄₄

6

R may be covalently linked;

R is a hydrogen atom, a hydrocarbon radical having 1 to 20 carbon atoms, wherein the carbon chain may be interrupted by non-adjacent - (CO) -, -0-, -S- or -NR groups and may be substituted by -CN or -halogen and may be covalently linked to R;

Q

S- or -NR groups may be interrupted and substituted with -CN or -halogen; and

Q

R is a hydrocarbon radical having 1 to 20 C atoms;

2 with the proviso that either R is a hydrogen atom or

1 2 at least one of the radicals R or R in direct

Neighboring to its shared nitrogen atom carries a - (C = O) group.

2. The method of claim 1, wherein is used as the aldehyde reagent (A) formaldehyde.

3. The method according to claim 1 or 2, wherein R is -CH ₂ - or

- (CH ₂ ) 3- means.

2

4. The method of claim 1 to 3, wherein the R a

Means hydrogen.

5. The method of claim 1 to 4, wherein the

Organopolysiloxane compounds (S) of the general formula (4)

AeR ⁹ ₃ -eSi0- (SiR ⁹ ₂ O) _m - ⁽⁹ siar Q) _n -SiR ⁹ ₃ - correspond _e Ae (4), where g

A and R have the meanings given in claim 1; e is 0 or 1; m is 0 or an integer of 1 to 200; n is 0 or an integer of 1 to 200, and m + n is 0 or an integer of 1 to 400; with the proviso that at least one radical A is present per molecule.

6. The method of claim 1 to 5, wherein the substrate is heated in the third step to 80 ° C to 180 ° C.

7. The method of claim 1 to 6, wherein the liquids (F) aliphatic alcohols having 1 to 10 carbon atoms are added as stabilizers.

8. A substrate comprising the organopolysiloxane compound (S) crosslinked by the process according to claims 1 to 7 with aldehyde reagent (A).

9. Substrates according to claim 8, which are selected from papers and films.