Patent Application
20080283425
The invention pertains to the field of two-component adhesion promoter compositions for surface pretreatment.
The invention likewise pertains to the use of a pack having two compartments.
Adhesion promoter substances have been used for a long time for improving adhesion, particularly that of adhesives and sealants. In particular, silane compounds and titanate compounds have long been known as adhesion promoter substances of this kind. It has emerged that specifically, depending on material and nature of the surfaces and on the adhesive or sealant used, it is necessary to select very specific adhesion promoter substances or mixtures thereof. These adhesion promoter compositions are used as primers or adhesion activators for the pretreatment of surfaces on which adhesion bonding, or sealing, is to take place. First, in the prior art, adhesion promoter substances of this kind are dissolved in an inert, volatile solvent, and as a result are storable for prolonged periods in the absence of moisture. When this adhesion promoter composition is applied to a surface, the volatile solvent evaporates, and the atmospheric moisture hydrolyzes the adhesion promoter substances and causes them to undergo condensation with one another and also, where appropriate, with polar groups on the surface. This reaction, however, requires a certain time until the adhesion is developed.
When these adhesion promoter substances come into contact with water, they undergo hydrolysis and condensation to form oligomers and/or polymers. When such oligomers, and particularly such polymers, are applied, however, the adhesion promoter effect is very frequently markedly poorer or is lost entirely. It has emerged that the development of adhesion is often inadequate if a very quick-crosslinking adhesive, in particular a very quick polyurethane adhesive, is applied to the adhesion promoter composition.
Because the prevailing trend in the market is away from volatile solvents—often also referred to as VOC (Volatile Organic Compounds), ways have been sought to produce aqueous adhesion promoter compositions. Aqueous silane primers of this kind are described for example in EP 0 577 014 B1 and EP 0 985 718 A2. U.S. Pat. No. 6,511,752 describes an aqueous primer based on a silane/titanate mixture. Common to all of these known aqueous silane compositions is the fact that their preparation requires a very costly and inconvenient production process with a very large number of added substances. In order to ensure a somewhat acceptable storage stability, these processes are limited, moreover, to specific silanes or titanates. The shelf life of the commercially available aqueous pretreatment products is very limited and is typically less than 6 months.
There are a variety of packaging designs, particularly in the food sector and in the pharmaceutical industry, which feature two chambers separate from one another.
FR 2 616 322, for example, describes a device having two compartments for the sterile dissolution of reactive components.
It is an object of the present invention, therefore, to provide an adhesion promoter composition which is stable on storage for a very long time, is easy to produce, and can be applied easily and reliably to a surface, along with an associated pack.
Surprisingly it has now emerged that this object can be achieved by a two-component adhesion promoter composition for surface pretreatment, as claimed in claim 1.
The core of the invention is that at least one hydrolyzable adhesion promoter substance and one compound which reacts with the adhesion promoter substance or which triggers or catalyzes condensation of the adhesion promoter substance are stored in compartments which are separated from one another by a dividing wall.
Surprisingly it has emerged that the results achievable with a freshly produced adhesion promoter solution are significantly better than with a composition of the same kind produced a long time beforehand.
Also found has been the use of a pack, as claimed in claim 18, and also a package, as claimed in claim 26.
A pack of this kind is very easy for the user to use and, as and when required, a freshly produced composition can be applied and hence profit obtained from the advantages. The pack is suitable in principle for all adhesion promoter substances which are stable in the absence of moisture, as a result of which it is possible to employ a significantly broader range of possible adhesion promoter substances, since the optimum adhesion promoter substance or composition can be used without having to take account of the storage stability of the mixed composition.
Exemplary embodiments of the invention are elucidated in more detail below, with reference to the drawings. Within the various figures, elements that are alike have been given the same reference symbols. The direction of forces is indicated by arrows.
Only those elements critical to the direct understanding of the invention have been shown. Motions and pressures have been indicated by arrows.
The present invention relates to a two-component adhesion promoter composition for surface pretreatment that comprises two components, the first component, K1, comprising at least one hydrolyzable adhesion promoter substance A which is selected from the group comprising organosilicon compounds, organotitanium compounds, organozirconium compounds, and mixtures thereof. Additionally the second component, K2, comprises at least one compound B which reacts with the adhesion promoter substance A or triggers or catalyzes condensation of the adhesion promoter substance A. In the unopened state, the first and the second components are present in two compartments separated from one another by at least one dividing wall.
The invention further provides for the use of a pack which has two compartments separated from one another by at least one dividing wall for the storage of two components K1, K2, as are described in detail in the two-component adhesion promoter composition in this document.
The invention further provides a package which is composed of a pack having two compartments separated from one another by at least one dividing wall and also of the two-component adhesion promoter composition of the invention.
The first component, K1, comprises or consists of at least one hydrolyzable adhesion promoter substance A.
The at least one hydrolyzable adhesion promoter substance A can be an organosilicon compound. Suitability is possessed in principle by all those organosilicon compounds known to the skilled worker that are used as adhesion promoters. Preferably this organosilicon compound carries at least one, in particular at least two, alkoxy group or groups which is or are attached via an oxygen-silicon bond directly to a silicon atom. Additionally the organosilicon compound carries at least one substituent which is attached via a silicon-carbon bond to the silicon atom and which optionally has a functional group which is selected from the group comprising oxirane, hydroxyl, (meth)acryloyloxy, amino, mercapto, and vinyl group. In particular the hydrolyzable adhesion promoter substance A is a compound of the formula (I)
The substituent R1 in this formula is a linear or branched, optionally cyclic, alkylene group having 1 to 20 C atoms, with or without aromatic components, and optionally with one or more heteroatoms, especially nitrogen atoms.
The substituent R2 is an alkyl group having 1 to 5 C atoms, especially methyl or ethyl.
Furthermore, the substituent R3 is an alkyl group having 1 to 8 C atoms, especially methyl, and the substituent X is an H or a functional group which is selected from the group comprising oxirane, OH, (meth)acryloyloxy, amine, SH, and vinyl.
Finally, a is one of the values 0, 1 or 2. Preferably a=0.
Preferred substituent R1 is methylene, propylene, methylpropylene, butylene or dimethylbutylene group. Preferably R1 is a propylene group.
Suitable organosilicon compounds are readily available commercially and with particular preference are selected from the group comprising methyltriacetoxysilane, ethyltriacetoxysilane, 3-methacryloyloxypropyltrialkoxysilanes, 3-aminopropyltrialkoxysilanes, bis[3-(trialkoxysilyl)propyl]amines, tris[3-(trialkoxysilyl)propyl]amines, 3-aminopropyltrialkoxysilanes, N-(2-aminoethyl)-3-aminopropyltrialkoxysilanes, N-(2-aminoethyl)-N-(2-aminoethyl)-3-aminopropyltrialkoxysilanes, 3-glycidyloxypropyltrialkoxysilanes, 3-mercaptopropyltrialkoxysilanes, vinyltrialkoxysilanes, methyltrialkoxysilanes, octyltrialkoxysilanes, dodecyltrialkoxysilanes, and hexadecyltrialkoxysilanes, particular suitability being possessed by the methoxysilanes and ethoxysilanes of the abovementioned compounds.
The at least one hydrolyzable adhesion promoter substance A can also be an organotitanium compound. Suitability is possessed in principle by all those organotitanium compounds known to the skilled worker that are used as adhesion promoters.
Particular suitability is possessed by organotitanium compound which carries at least one functional group which is selected from the group comprising alkoxy group, sulfonate group, phosphates, carboxylate group, and acetylacetonate, or carries mixtures thereof, and which is attached via an oxygen-titanium bond directly to a titanium atom.
Alkoxy groups which have proven particularly suitable are, in particular, isopropoxy substituents and so-called neoalkoxy substituents, particularly those of the following formula
Sulfonic acids which have proven particularly suitable are, in particular, aromatic sulfonic acids whose aromatics are substituted by an alkyl group. Considered preferred sulfonic acids are radicals of the following formula
Carboxylate groups which have proven particularly suitable are, in particular, carboxylates of fatty acids. Considered preferred carboxylates are stearates and isostearates.
In all of the above formulae the dashed bond in this case shows the connection to the titanium atom.
Organotitanium compounds are available commercially, as for example from the company Kenrich Petrochemicals or DuPont. Examples of suitable organotitanium compounds are, for example, Ken-React® KR TTS, KR 7, KR 9S, KR 12, KR 26S, KR 33DS, KR 38S, KR 39DS, KR44, KR 134S, KR 138S, KR 158FS, KR212, KR 238S, KR 262ES, KR 138D, KR 158D, KR238T, KR 238M, KR238A, KR238J, KR262A, LICA 38J, KR 55, LICA1, LICA 09, LICA 12, LICA 38, LICA 44, LICA 97, LICA 99, KR OPPR, KROPP2 from Kenrich Petrochemicals, or Tyzor® ET, TPT, NPT, BTM AA, AA-75, AA-95, AA-105, TE, ETAM from DuPont. Those preferred are Ken-Reacts KR 7, KR 9S, KR 12, KR 26S, KR 38S, KR44, LICA 09, LICA 44 and Tyzor® ET, TPT, NPT, BTM, AA, AA-75, AA-95, AA-105, TE, ETAM from DuPont.
The at least one hydrolyzable adhesion promoter substance A can additionally be an organozirconium compound. Suitability is possessed in principle by all those organozirconium compounds known to the skilled worker that are used as adhesion promoters. Particularly suitable organozirconium compounds are those which carry at least one functional group which is selected from the group comprising alkoxy group, sulfonate group, carboxylate group, and phosphate, or carries mixtures thereof, and which is attached via an oxygen-zirconium bond directly to a zirconium atom.
Alkoxy groups which have proven particularly suitable are, in particular, isopropoxy substituents and so-called neoalkoxy substituents, particularly those of the following formula
Sulfonic acids which have proven particularly suitable are, in particular, aromatic sulfonic acids whose aromatics are substituted by an alkyl group. Considered preferred sulfonic acids are radicals of the following formula
Carboxylate groups which have proven particularly suitable are, in particular, carboxylates of fatty acids. Considered preferred carboxylates are stearates and isostearates.
In all of the above formulae the dashed bond in this case shows the connection to the zirconium atom.
Organozirconium compounds are available commercially, as for example from the company Kenrich Petrochemicals. Examples of suitable organozirconium compounds are, for example, Ken-React® NZ 38J, NZ TPPJ, KZ OPPR, KZ TPP, NZ 01, NZ 09, NZ 12, NZ38, NZ 44, NZ 97.
Additionally it is possible for the first component K1 to comprise mixtures of at least one organosilicon compound with at least one organotitanium compound and/or with at least one organozirconium compound.
Likewise possible are mixtures of at least one organotitanium compound with at least one organozirconium compound. Preferred mixtures are those of at least one organosilicon compound with at least one organotitanium compound.
Particularly preferred mixtures are those of two or more organosilicon compounds or mixtures of one organosilicon compound with an organotitanium compound or organozirconium compound, respectively.
Mixtures of organosilicon compounds which have proven particularly appropriate are mixtures of adhesion promoter substances A of the formulae (I) where at least one of them carries substituents H as substituents X and at least one of these substances carries a functional group which is selected from the group comprising oxirane, (meth)acryloyloxy, amine, SH, and vinyl as substituents X. These mixtures preferably comprise mixtures of at least one alkyltrialkoxysilane with an aminoalkyltrialkoxysilane and/or mercaptoalkyltrialkoxysilane.
The second component, K2, comprises or consists of at least one compound B which reacts with the adhesion promoter substance A or which triggers or catalyzes condensation of the adhesion promoter substance A.
The compound B which reacts with the adhesion promoter substance A or which triggers or catalyzes condensation of the adhesion promoter substance A is preferably an organotin compound or an acid.
In one preferred embodiment the compound B is an organotin compound and preferably represents a dialkyltin diacetylacetonate or a dialkyltin dicarboxylate, and in particular is dibutyltin dilaurate or dibutyltin diacetate. Preferably compound B is dibutyltin dilaurate.
In a further preferred embodiment the compound B is an acid. The acid may be an organic acid or an inorganic acid. The acid typically has a pKa1 of less than 6.
Particularly suitable inorganic acids are acids containing phosphorus, acids containing sulfur. Those which have proven particularly suitable are sulfonic acid or phosphoric acid, especially sulfuric acid.
Particularly suitable organic acids include formic, acetic, amino acid. Acetic acid has proven particularly suitable.
Further constituents in the first K1 and/or second K2 component are possible. Particular mention may be made for this purpose of typical constituents such as solvents, binders, fillers, mixing assistants, and additives. Preferred solvents are volatile solvents such as water, alcohols, especially ethanol, isopropanol, butanol, aldehydes or ketones, especially acetone, methyl ethyl ketone, hydrocarbons, especially hexane, heptane, cyclohexane, xylene, toluene, white spirit, and mixtures thereof, especially ethanol, methanol, isopropanol or hexane.
Suitable binders are particular film-forming binders, such as prepolymers and adducts of polyisocyanates or epoxy resins. Preference is given to polyurethane prepolymers which contain isocyanate groups and are prepared from polyols and polyisocyanates.
Preferred fillers are carbon blacks, pyrogenic silicas, chalks, whose surface has been modified if required.
Mixing assistants are preferably beads, especially metal beads or glass beads.
Additives particularly include flow control agents, defoamers, surfactants, biocides, antisettling agents, stabilizers, inhibitors, pigments, dyes, corrosion inhibitors, and odorants.
When selecting the additional possible constituents for the first K1 and/or second K2 component, however, it must be borne in mind that these additional constituents do not lead to storage stability problems or do not react with the compounds present in the respective components, particularly A, and/or B.
At room temperature the first K1 and second K2 components have a consistency which is between liquid and pulverulent, it being necessary for at least one of the components to have a certain liquid fraction. With particular preference the first K1 and the second K2 components are liquid, because liquid components, and especially highly mobile liquid components, can be mixed more effectively than highly pasty components.
With preference the first K1 and second K2 components are a solution, a suspension or a dispersion. In the case of a suspension or a dispersion, the stability is an important feature. The stability can be controlled by the skilled worker by means, for example, of varying solvent, concentrations, production process parameters, or by using suitable additives, especially surfactants, emulsifiers, co-emulsifiers or stabilizers.
Particularly suitable first K1 and second K2 components have a storage stability of at least 6 months, in particular at least 9 months, without instances of precipitation or separation. Although the absence of instances of precipitation or separation is preferred, slight precipitation or separation is nevertheless not detrimental if it can be reversed by shaking, in particular by shaking for less than 10 minutes.
In one preferred embodiment of a two-component adhesion promoter composition the first component comprises at least one organosilicon compound A, at least one polyurethane prepolymer having at least two isocyanate groups, and, if desired, carbon black and, if desired, a volatile solvent.
In another preferred embodiment of a two-component adhesion promoter composition the first component comprises at least one organosilicon compound A and/or at least one organotitanium compound and/or at least one organozirconium compound and the second component comprises water and at least one acid. The pH of the mixed two-component adhesion promoter composition is preferably between 2 and 8, in particular between 3 and 5.
The compartments in which the two components K1 and K2 are located are separated from one another by at least one dividing wall. The possible and preferred embodiments of the compartments and of the dividing walls are described schematically below.
The seal 3′ is manufactured from an elastic material, of the kind typically used for the sealing of liquids.
a) shows a configuration with one thread 9, while
In
In
In
In
In
The embodiment described in
In
In all of the figures the first component K1 can be present in the first compartment 1 and the second component K2 can be present in the second compartment 2, or else the first component K1 can be present in the second compartment 2 and the second component K2 can be present in the first compartment 1.
The size of the compartments is preferably such that at least one compartment 1, 2 has a greater volume than the volume of the component K1, K2 present in it. With particular preference the volume not occupied by said component corresponds at least to the volume of the other component.
Moreover, the volume ratio K1/K2 of the first component K1 to the second component K2 is between 1000/1 and 1/1000, in particular between 200/1 to 10/1 or between 1/200 to 1/10. Preferably the volume ratio K1/K2 is between 200/1 to 20/1 or between 1/200 to 1/20.
At least the walls of the compartment in which the first component K1 is stored are preferably of one or more materials which impervious to diffusion of water in liquid or gaseous state or at least so impermeable that the desired storage stability is not adversely affected. Particularly suitable for this purpose are aluminum or glass or composites. Thus, for example, component 1 can be stored in an aluminum pouch or in an aluminum-coated plastic pouch. This kind of compartment has the advantage that the wall can be severed anywhere, and therefore that precise positioning of the pouch is not required. Pouches of this kind are suitable in particular for the embodiments according to
The package 6 is produced by filling of the compartments 1 and 2 with components K1 and K2, followed where appropriate by the assembly of the pack. The package has good storage stability, typically of at least 6 months, in particular of at least 9 months. If the package 6 is to be used to apply an adhesion promoter, it can be activated specifically. For this purpose the dividing wall 3 must be removed or severed so that the components K1 and K2 can make contact, mix and/or react. Mixing may be assisted by shaking. Subsequently the adhesion promoter composition prepared in this way is removed from the package 6 and applied to a surface on which adhesive bonding or sealing is to take place. Depending on the nature of the chosen constituents in components K1 and K2, it may be necessary to allow a short time, typically less than half an hour, to elapse between contacting of the two components and their application, in order to achieve an optimum adhesion promoter effect. Preferably, however, the adhesion promoter composition is applied immediately. The surface may be composed of very different material, particular preference being given to glass, glass ceramics, metals, paints, and plastics. Where appropriate it may be necessary for the surface to be pretreated, prior to application of the adhesion promoter, by further chemical, physical or physicochemical methods. For application it is preferred to mount a porous cover 20, in particular a felt or a sponge, on a package 6 with aperture 10. A porous cover 20 of this kind is typically affixed to a shaped part which ensures, in the edge region, an assembly with the pack. This assembly is achieved preferably by way of a screw connection via a thread 9. The two-component adhesion promoter composition is applied in a layer thickness of less than 1 millimeter, typically in a layer thickness of less than 100 micrometers. If the adhesion promoter composition comprises fillers and/or binders, a layer thickness between 1 and 100 micrometers, in particular between 1 and 20 micrometers, is preferred. If the adhesion promoter composition comprises no fillers and no binder, a layer thickness is preferred which is between one molecular monolayer of the compound A and 50 micrometers, in particular between 2 nanometers and 10 micrometers, in particular between 10 nanometers and 1 micrometer.
Preparation, Examples 1-5
Components K1 and K2 were prepared separately from one another by mixing with stirring, the mixing of the three constituents of the first component K1 taking place under nitrogen.
The components were mixed and after 30 minutes the mixture was applied to different substrates by spreading using an impregnated paper cloth (Tela or Kleenex®). Subsequently the adhesive was applied after 10 minutes.
Example 6 is based on Sika® Aktivator (available commercially from Sika Schweiz AG). Sika® Aktivator is an adhesion promoter composition comprising an organosilicon compound A and an organotitanium compound A and also a volatile solvent. The Sika Aktivator is stored in one compartment, and dibutyltin dilaurate B in a second compartment. The amounts are such that 31 by weight of dibutyltin dilaurate is used, based on the weight of the Sika® Aktivator.
The components were mixed. Shortly after mixing, a yellow-orange coloration became apparent. After 10 minutes the mixture was applied to the various substrates by spreading with an impregnated paper cloth (Tela or Kleenex®). Subsequently the adhesive was applied after 10 minutes.
The AlMgSi1 was roughened using abrasive paper.
The substrates were cleaned with an isopropanol/water mixture (1/1 w/w). After a waiting time of 5 minutes, the adhesion promoter composition was applied. In the case of glass, the tin side was not used for the adhesions.
Following the application of the adhesion promoter composition, a bead of an adhesive was applied to it. The adhesives in question were the following moisture-curing polyurethane or silane-modified polyurethane adhesives, available commercially from Sika Schweiz AG:
The adhesive was tested after a cure time of 7 days of climate chamber storage (‘CC’) (23° C., 50% relative humidity) and after subsequent water storage for 7 days at 25° C. (‘WB’) and also after hot wet storage (‘CP’) for 7 days at 70° C. and 100% relative humidity.
The adhesion of the adhesive was tested by means of the ‘bead test’. In this test an incision is made at the end just above the adhesion face. The incised end of the bead is held with round pliers and pulled from the substrate. This is done by carefully rolling up the bead on the tip of the pliers, and placing a cut vertical to the bead pulling direction down to the bare substrate. The rate of bead removal is selected so that a cut has to be made approximately every 3 seconds. The test length must amount to at least 8 cm. An assessment is made of the adhesive which remains on the substrate after the bead has been pulled off (cohesive fracture). The adhesion properties are evaluated by estimation of the cohesive fraction of the adhesion face:
1=>95% cohesive fracture
2=75-95% cohesive fracture
3=25-75% cohesive fracture
4=<25% cohesive fracture
5=adhesive fracture
The addition “F” indicates that the adhesive exhibits film adhesion on the primer, so that the fracture occurs between primer and adhesive. Test results with cohesive fractures of less than 75% are considered inadequate.
High-speed strength: the early strength was determined by means of a high-speed tensile test after 1 hour of curing under different curing conditions. Measuring speed 1 m/s.
FOG: the early strength was measured by means of a Zwick apparatus. Measuring speed 200 mm/min after curing for 2 hours at 23° C. and 50% relative humidity.
Ref. 1 is the comparative example without application of adhesion promoter. In the case of Ref. 2 only water was applied and in Ref. 3 an application of water/surfactant (concentration analogous to example) was carried out. Application took place in the same way as for the adhesion promoter compositions, that is, by means of impregnated paper cloth (Tela or Kleenex®).
In the case of Example 6 the development of early strength was determined in comparison to Sika® Aktivator. For that purpose, aluminum panels were cleaned with isopropanol/water mixture as described, after which the primer Sika® Primer-206 G+P was applied with a brush, left to evaporate for 10 minutes at 25° C., and subsequently Example 6, or, for comparison, Sika® Aktivator, was applied by means of impregnated paper cloth (Tela or Kleenex®) and, finally, bonded with SikaTack®-Ultrafast or SikaTack®-Plus Booster.
The results show that with the two-component adhesion promoter compositions of the invention it is possible to achieve excellent adhesion on different substrates and with different adhesives, which is also manifested in a rapid development of adhesion.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04006906.4 | Mar 2004 | EP | regional |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10593623 | Jun 2008 | US |
| Child | 12000850 | US |
