DE202015106261U1 - sealant - Google Patents

Abstract

Photoinitiatable, in particular UV-curable, formulations, in particular sealants, comprising a) at least one polyfunctional, (meth) acrylated urethane resin, b) at least one monofunctional (meth) acrylate, c) at least one trifunctional (meth) acrylate, as well as conventional additives and initiators ,

Description

All documents cited in the present application are incorporated by reference in their entirety into the present disclosure (= incorporated by reference in their entirety).

The present invention relates to novel formulations, in particular sealants.

State of the art:

Gaskets are well known and widely used in industry. Apart from metallic seals, plastic seals are often used. General literature on seals and sealants are in standard works, such. B Römpp Chemielexikon, Ullmann Encyclopedia of Industrial Chemistry, Kirkh-Othmer etc. find. In many cases seals are prefabricated. This happens when the geometry is not too complicated and the number of pieces is significant (eg O-rings). For tailor-made applications in small numbers, the manufacture of the gasket during the assembly of the part has proved to be advantageous. This liquid precursors are applied to a part and then cured. The materials used there are, for example, PU foams, silicones, polyacrylates, u. s. w. The prerequisite for the application of this technique is that the precursors can be brought into the desired shape and that the curing takes place quickly and by the retention of the geometry. The cured seals must have a certain elasticity adapted to the application. The application of the liquid precursor is usually done mechanically by dispensers in often fully automated assembly lines. Manually grasp such materials from cartridges with a corresponding squeezing apply. The objects to be sealed are often boxes in which electronics are to be protected, mechanical parts that are covered for safety reasons and others that need to be protected from contamination. The applications are numerous in just about all industrial sectors.

When using seals always make sure that they are adapted to the operating conditions. Pressure, temperature, humidity, liquid water, oils, dust, u. s. w. are to be withstood by the sealing material without changing the properties. Therefore, appropriate tests must be carried out in advance.

The suitability of an acrylic formulation for producing a UV-curable seal for an aluminum housing in the engine compartment of automobiles underlies this invention.

Task:

The object of the present invention is to provide a formulation, in particular a sealant, which can be applied to geometrically irregular workpieces, in particular also of aluminum-based materials, without the workpiece surfaces having to be cleaned and polished. The formulations should be able to be cured quickly by means of light and / or UV light and then be able to withstand an overpressure of at least 3.5 bar.

Solution:

• a) mindestens ein polyfunktionelles, (meth)acryliertes Urethanharz,
• b) mindestens ein monofunktionelles (Meth)acrylat,
• c) mindestens ein trifunktionelles (Meth)acrylat,

sowie übliche Additive und Initiatoren, gelöst.This object is achieved by photoinitiable, in particular UV-curable, formulations, in particular sealing compounds

• a) at least one polyfunctional, (meth) acrylated urethane resin,
• b) at least one monofunctional (meth) acrylate,
• c) at least one trifunctional (meth) acrylate,

as well as customary additives and initiators.

Definition of terms:

In the context of the present invention, all quantities are, unless stated otherwise, to be understood as weight data.

In the context of the present invention, the term "room temperature" means a temperature of 20 ° C. Temperatures are, unless otherwise stated, in degrees Celsius (° C) Unless otherwise specified, the reactions or process steps given at atmospheric pressure / atmospheric pressure, d. H. at 1013 mbar.

In the context of the present invention, the expression "and / or" includes both any and all combinations of the elements listed in the respective list.

In the context of the present invention, the term "bead" is used in the usual sense for sealing elements.

In the context of the present invention, unless otherwise stated, the term "photoinitiator" is understood to mean both photosensitizers and photoinitiators in the narrower sense.

The term (meth) acrylic is intended in the context of the present invention to include both methacrylic and acrylic or mixtures of both. The same applies to inflectional forms.

Detailed description:

• a) mindestens ein polyfunktionelles, (meth)acryliertes Urethanharz,
• b) mindestens ein monofunktionelles (Meth)acrylat,
• c) mindestens ein trifunktionelles (Meth)acrylat,

sowie übliche Additive und Initiatoren.The present invention relates to photoinitiatable, in particular UV-curable, formulations, in particular sealants, comprising

• a) at least one polyfunctional, (meth) acrylated urethane resin,
• b) at least one monofunctional (meth) acrylate,
• c) at least one trifunctional (meth) acrylate,

as well as usual additives and initiators.

• a) 70–80% mindestens eines polyfunktionellen, (meth)acrylierten Urethanharzes, bevorzugt eines difunktionellen Urethan(meth)acrylats, insbesondere eines aliphatischen Urethandiacrylats,
• b) 15–20% mindestens eines monofunktionellen (Meth)acrylats, bevorzugt eines THF-modifizierten (Meth)acrylats, insbesondere Tetrahydrofurfurylacrylat,
• c) 1–3% mindestens eines trifunktionellen (Meth)acrylates, bevorzugt eines Polyethylenglykolketten enthaltenden trifunktionellen (Meth)acrylates,
• d) 4–7% mindestens ein Rheologieadditiv, bevorzugt pyrogene Kieselsäure,
• e) 0–3% weitere Additive, bevorzugt 0%,
• f) 0,1–3% mindestens ein Photoinitiator, bevorzugt UV-Initiator,

wobei die Formulierung eine Viskosität im Bereich von 20000 bis 40000 mPas, bevorzugt 25000 bis 30000 mPas, insbesondere 30000 mPas, jeweils bei 23°C aufweist und die Prozentangaben Gewichtsprozent sind und sich jeweils auf 100% addieren.The present invention is in particular a formulation, in particular sealant, consisting of

• a) 70-80% of at least one polyfunctional, (meth) acrylated urethane resin, preferably a difunctional urethane (meth) acrylate, in particular an aliphatic urethane diacrylate,
• b) 15-20% of at least one monofunctional (meth) acrylate, preferably a THF-modified (meth) acrylate, in particular tetrahydrofurfuryl acrylate,
• c) 1-3% of at least one trifunctional (meth) acrylate, preferably a trifunctional (meth) acrylate containing polyethylene glycol chains,
• d) 4-7% at least one rheology additive, preferably fumed silica,
• e) 0-3% further additives, preferably 0%,
• f) 0.1-3% at least one photoinitiator, preferably UV initiator,

wherein the formulation has a viscosity in the range of 20,000 to 40,000 mPas, preferably 25,000 to 30,000 mPas, in particular 30,000 mPas, each at 23 ° C and the percentages are percent by weight and each add up to 100%.

The present invention furthermore relates to the use of the formulations according to the invention as sealants for housings.

The polyfunctional, (meth) acrylated urethane resins a) represent the main binder component of the formulations. These preferably have viscosities of from 1000 to 100,000 mPas.

Usable examples include the Ebecryl products of Cytec, in particular Ebecryl 230. In one variant, difunctional urethane acrylates having a viscosity of 40,000 mPas at 23 ° C are used.

The monofunctional (meth) acrylates b) serve to crosslink the formulation components. Usable examples include THF acrylate derivatives such as tetrahydrofurfuryl acrylates (eg Qualicure GM61P00 from Jobachem / Qualypoly Chem or AginSyn 2839 from Agi Corporation). {

The trifunctional (meth) acrylates c) are advantageous for the cohesion of the sealing bead and, moreover, lead to a certain crosslinking of the formulation. Preference is given to using trifunctional (meth) acrylates c) containing polyethylene glycol chains.

Useful examples are ethoxylated trimethylolpropane triacrylates such as Photomer 4149 F from IGM Resins.

The rheology additives d) serve to control the flow properties of the formulation. Usable examples are fumed silicas such. B Aerosil ^(R) types. In one variant, Aerosil 202-S ^{(R) is} used.

The further additives e) serve to adjust further properties of the formulation or the improvement of the processability, etc. Such additives which are suitable for use in sealants are known to the person skilled in the art. It may be within the scope of the present invention z. B leveling additives, deaerating additives, adhesion promoters, defoamers, corrosion inhibitors, pigments, light stabilizers such as UV absorbers and / or reversible radical scavengers (HALS), antioxidants, flame retardants and others are used.

In a variant of the present invention, only defoamers and adhesion promoters are used as further additives e). Examples of suitable defoamers are in particular silicone-free foam inhibitors and defoamers, a commercially available example is WorleeAdd 678. Examples of suitable adhesion promoters are silane derivatives, in particular 3-glycidoxypropyltrimethoxysilane, which u. a. as KMB-403 is available from ShiEtsu.

Examples of suitable additives are well known to the skilled person from his daily work and are described, for example, in textbooks such as "Paint Additives" by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998 , or D. Stoye and W. Freitag (Editors), "Paints, Coatings and Solvents", Second, Completely Revised Edition, Wiley-VCH, Weinheim, New York, 1998 , described.

The photoinitiators f) serve to assist or facilitate the curing reaction of the formulation. Preference is given to UV initiators, i. H. Useful examples are alpha-hydroxy, alpha-alkoxy, alpha-amino-aryl ketones, acyl phosphine oxides, especially bis (2,4,6-trimethylbenzoyl) -Uhylphosphinoxid, erhätlich z. B. as Irgacure 819. In one variant phosphine oxides are used, in particular

The formulations of the present invention have the advantage of being free of organic solvents.

Another object of the present invention are housings comprising the formulations of the invention. The housings are preferably sealed with the formulations according to the invention.

The UV-curable formulation according to the invention adheres very well to non-polished substrates and the curing is not inhibited by impurities. After curing, it is flexible enough to work as a seal. It is gas-tight and withstands overpressure well.

The formulations according to the invention, in particular sealants, are prepared, for example, by mixing the constituents described above in suitable mixing units such as stirred tanks, stirred mills, extruders, kneaders, Ultraturrax, in-line dissolvers, static mixers, micromixers, sprocket dispersers, pressure relief nozzles, vacuum dissolvers and / or Microfluidizer. This can be done under exclusion of light of a wavelength <550 nm or with complete exclusion of light to prevent premature crosslinking of the compositions of the invention.

The application of the formulations according to the invention, in particular sealants, on the workpieces, for example, by conventional and known application methods, such as. B Spraying, spraying, knife coating, brushing, pouring, dipping, trickling or rolling, preferably by means of dispensers, in particular by numerically controlled dispensers.

In the application, it is possible to work with the exclusion of light and / or UV radiation in order to avoid premature crosslinking of the formulation according to the invention.

In a variant of the present invention, the applied formulations according to the invention are cured with UV radiation. A radiation dose of 2,000 to 10,000, preferably 3,000 to 9,000, preferably 4,000 to 8,000 and particularly preferably 5,000 to 7,000 mJ / cm ² is preferably used during the irradiation, the range around 6,000 mJ / cm ^{2 being} very particularly preferred. The radiation intensity can vary widely. It depends in particular on the radiation dose on the one hand and the duration of irradiation on the other hand. The duration of irradiation depends on the feed rate of the substrates in the irradiation facility and vice versa for a given radiation dose. As radiation sources for the UV radiation, all conventional and known UV lamps can be used. There are also flashlights into consideration.

• A) die einzelnen Bestandteile a) bis f) zur Verfügung gestellt werden,
• B) die Bestandteile miteinander vermischt werden.

Furthermore, the subject of the present invention is a process for the preparation of the formulations according to the invention, characterized in that

• A) the individual components a) to f) are made available,
• B) the ingredients are mixed together.

• B1) zuerst Vermischen der Bestandteile a), b) und d),
• B2) danach Zumischen der Bestandteile c), e) und f) und
• B3) Homogenisieren der Bestandteile a) bis f).

In a preferred variant, step B) is subdivided into

• B1) firstly mixing the constituents a), b) and d),
• B2) then admixing the components c), e) and f) and
• B3) Homogenizing the constituents a) to f).

The formulations of the invention are particularly well suited, for example, to a geometrically irregular housing made of diecast aluminum with wall thickness 10 mm with dimensions of about 300 mm x 300 mm, in a width of 5 mm and with a wet film layer of about 1-3 mm to be applied to the non-polished surfaces as a sealant. The application of the adhesive bead can be done fully automatically with a numerically controlled dispenser. The curing of the sealant can be done easily in a time of 1-3 minutes. Since the size of such a housing makes thermal curing uneconomical, curing by UV light is to be preferred, which is fulfilled by the formulations according to the invention, which completely cures in this time frame. The background and contamination on this do not inhibit the cure.

A component assembled in this way maintains a nitrogen overpressure of 4 bar.

• i) Bereitstellen eines Gehäuses umfassend entweder
• ia) mindestens zwei Gehäuseteil, oder
• ib) eine Öffnung
• iia) im Fall ia) Auftragen der erfindungsgemäßen Formulierung auf eines oder beide Bauteile, oder
• iib) im Fall ib) Auftragen der erfindungsgemäßen Formulierung auf den abzudichtenden Bereich,
• iiia) im Fall ia) Zusammenfügen der Gehäuseteile, und
• iv) Aushärten der erfindungsgemäßen Formulierung durch Einstrahlung von Licht, bevorzugt UV-Licht.

Accordingly, the present invention likewise provides a method for sealing casings using the formulations according to the invention, characterized in that it comprises the process steps i), ii), iii) and iv) as follows:

• i) providing a housing comprising either
• ia) at least two housing part, or
• ib) an opening
• iia) in the case of ia) applying the formulation of the invention to one or both components, or
• iib) in the case of ib) applying the formulation of the invention to the area to be sealed,
• iiia) in the case of ia) joining the housing parts, and
• iv) curing of the formulation according to the invention by irradiation of light, preferably UV light.

Last but not least are seals containing or consisting of a formulation according to the invention, which is partially or fully cured, the subject of the present invention.

Corresponding seals, which are only partially cured, can be used as adhesive seals, d. H. their application is greatly facilitated and complete curing can then take place after the adhesive seal has been applied to the desired location.

By the present invention, it is possible to seal housing so that the contents of the housing against gases, moisture, dirt, etc. is protected even at an overpressure.

Corresponding housings comprising a formulation according to the invention, preferably those which are sealed with a formulation according to the invention, are likewise provided by the present invention. Accordingly, the present invention also relates to the use of the formulations according to the invention for housings, preferably for the sealing of housings.

The various embodiments of the present invention, e.g. B but not exclusively those of the various dependent claims may be combined with each other in any manner.

The invention will now be elucidated with reference to the following non-limiting examples.

Example:

The quantities indicated were weighed into a vacuum dissolver and then dispersed to homogeneity: 144 g of an aliphatic bifunctional urethane acrylate (Ebecryl 230) having a viscosity of 2000 mPas / 23 ° C., 36 g of THF acrylate derivative (Qualicure GM61P00), 11 g of Aerosil 202 ^(R) . Thereafter, the batch was diluted with 4 g of an ethoxylated trimethylolpropane triacrylate (Photomer 4149 F), 1.6 g of a commercial adhesion promoter (KMB-403), 2 g of a defoamer (WorleeAdd 678) and 0.6 g of a photoinitiator (type phosphine oxide) ( Irgacure 819). The formulation had a viscosity of 30,000 mPas at 23 ° C. A 5 mm wide bead was automatically applied to the component. The curing was carried out in a UV continuous furnace (1 m / min), which was equipped with a UV lamp (6000 mJ / cm2). The component was assembled and tested with 4 bar nitrogen pressure. After 12 hours there was no pressure drop.

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 non-patent literature

• "Paint Additives" by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998 [0025]
• D. Stoye and W. Freitag (Editors), "Paints, Coatings and Solvents", Second, Completely Revised Edition, Wiley-VCH, Weinheim, New York, 1998 [0025]

Claims (4)

Photoinitiable, in particular UV-curable, formulations, in particular sealants, comprising a) at least one polyfunctional, (meth) acrylated urethane resin, b) at least one monofunctional (meth) acrylate, c) at least one trifunctional (meth) acrylate, as well as usual additives and initiators. A formulation according to claim 1 consisting of a) 70-80% of at least one polyfunctional, (meth) acrylated urethane resin, preferably a difunctional urethane (meth) acrylate, b) 15-20% of at least one monofunctional (meth) acrylate, preferably of a THF-modified (meth) acrylate, c) 1-3% of at least one trifunctional (meth) acrylate, preferably a trifunctional (meth) acrylate containing polyethylene glycol chains, d) 4-7% at least one rheology additive, preferably fumed silica, e) 0-3% further additives, f) 0.1-3% at least one photoinitiator, preferably UV initiator, wherein the formulation has a viscosity in the range of 20,000 to 40,000 mPas, preferably 25,000 to 30,000 mPas, in particular 30,000 mPas, each at 23 ° C and the percentages are percent by weight and each add up to 100%. A formulation according to any one of claims 1 or 2 consisting of a) 71-74% of an aliphatic difunctional Urethanhanacrylats with a viscosity of 2000 mPas / 23 ° C, b) 17-19% tetrahydrofurfuryl acrylate, c) 1.5-2.5% of an ethoxylated trimethylolpropane triacrylate, d) 4.5-6.5% fumed silica, e) 0.5-1.5% of a coupling agent and 1.5-2.5% of a defoamer, f) 1,0,5% of a phosphine oxide, where the percentages are by weight and add up to 100% each. A seal comprising or consisting of a partially or fully cured formulation according to any one of claims 1 to 3.