HK1156962B

HK1156962B - Novel matting agent for uv varnishes

Info

Publication number: HK1156962B
Application number: HK11111308.1A
Authority: HK
Inventors: K．贝纳; H.D.克里斯汀; G-G.林德纳; K.梅尔
Original assignee: 赢创德固赛有限公司
Priority date: 2009-09-29
Filing date: 2011-10-20
Publication date: 2015-07-31

Description

novel matting agents for UV coatings

Technical Field

The invention relates to matt silica-containing UV coatings, the surface of which is modified by treatment with organopolysiloxanes containing multiple bonds, as described below, so that they are particularly well suited for use as matting agents for UV coatings, and to a method for producing said coatings or surface-modified silica.

Background

Matting of UV coatings has been a significant problem. In contrast to other coating systems, no shrinkage occurs during curing for UV coatings. Whereby a rough surface cannot be formed and the particles added as a matting agent cannot exert their matting effect.

H.d. christian tested various different fumed and precipitated silicas as matting agents in UV coatings in an extensive study (see RadTech Europe 2005 Conference and exclusion), h.d. christianNot only untreated silica but also silica coated with PE wax and silica coated with polysiloxane were tested. The results obtained by chrisian are that matting of UV coatings remains a complex problem and there is no indication in this study of which matting agent is the matting agent selected for UV coatings.

Thus, there is still a great need for silica-based matting agents developed specifically for matting of UV coatings.

Disclosure of Invention

It is therefore the object of the present invention to provide surface-modified silicas which, when used as matting agents in UV coatings, in particular in UV-curable varnishes, exhibit better performance properties than hitherto known matting agents based on silica. It is also intended to provide a process for preparing the surface-modified silica, and to provide a process for preparing the coating.

Other tasks not explicitly mentioned arise from the general context of the subsequent description, examples and claims.

It has surprisingly been found that surface modification of silica with organopolysiloxanes containing multiple bonds leads to products which are outstandingly suitable as matting agents for UV coatings, in particular UV-curable varnishes.

In addition to UV coatings which are particularly difficult to matt, all other coating systems can be matt with the products according to the invention.

The UV-curable varnishes according to the invention also have the advantage, owing to the novel matting agents according to the invention: it has improved transparency, especially in the liquid state, compared to UV coatings delustred with silica coated with PE wax. Here, the settling properties of the polysiloxane-modified silica are at least as good as those of polyethylene wax (PE wax) modified silica. The silicas coated with polysiloxanes containing multiple bonds used according to the invention therefore have advantages over matting agents covered with PE waxes which often lead to fogging of the clearcoat.

It has been found that silica can be modified by coating with organopolysiloxanes containing multiple bonds, so that UV coatings having a refractive index of 1.4000 to 1.5000, in which the silica according to the invention is incorporated, have excellent transparency. Equivalent coatings comprising the silica according to the invention as matting agent show a significantly improved transparency, even in the liquid state, compared to UV coatings comprising conventional silica covered with PE wax as matting agent and having a refractive index of 1.4000 to 1.5000, with excellent sedimentation properties. Varnishes matted with conventional matting agents are generally cloudy in the liquid state, in contrast to varnishes matted with precipitated silicas according to the invention which are substantially clear and transparent even in the liquid state.

The subject of the invention is therefore a UV coating, preferably a UV-curable varnish, containing at least one surface-modified silica, characterized in that at least part of the silica particles are covered with at least one organopolysiloxane, and at least one organopolysiloxane comprises at least one multiple bond.

The subject of the invention is furthermore a process for preparing the surface-modified silicas used according to the invention, characterized in that dried silica or a suspension or a cake of silica is brought into contact with at least one organopolysiloxane comprising at least one multiple bond.

The surface-modified silicas used according to the invention are preferably amorphous silicas, particularly preferably precipitated silicas, pyrogenic silicas, semigels or silica gels. The differences between the silica types are known to the person skilled in the art and can be found, for example, in Ullmanns Encyclopedia of Chemistry, 5 th edition, volume 23. Precipitated silicas, semigels and silica gels are particularly preferred for economic reasons and for their surface properties, i.e.the number of coupling sites in the case of polysiloxanes. Particular preference is given to using precipitated silicas.

The terms "precipitated silica" and "precipitated silica" are used synonymously within the scope of the present invention. The terms "organopolysiloxane" and "polyorganosiloxane" are also used synonymously.

The silicas used according to the invention are preferably characterized by at least one of the following physico-chemical parameters:

it has been shown that the DBP value of the silicas used according to the invention can be correlated to some extent with the extinction efficiency. Furthermore, the DBP value is important in order to ensure optimum absorption by the organopolysiloxane. Therefore, the DBP value of the silica used according to the invention is preferably 100-600g/100g, particularly preferably 150-500g/100g, particularly preferably 200-450g/100g and particularly preferably 250-400g/100 g.

In order to be able to achieve a particularly good matting effect, but at the same time also to make it possible to achieve a coating surface which is not excessively rough, the surface-modified silicas used according to the invention have an average particle size d₅₀Preferably from 1 to 50 μm, particularly preferably from 1 to 40 μm, very particularly preferably from 1 to 30 μm, particularly preferably from 2 to 20 μm and very particularly preferably from 3 to 15 μm. The average particle size may vary depending on the layer thickness of the coating.

The surface modification influences the sedimentation behavior of the surface-modified silicas used according to the invention. It has been shown to be particularly advantageous for the carbon content of the surface-modified silicas used according to the invention to be in the range from 1 to 20% by weight, particularly preferably from 1 to 10% by weight and very particularly preferably from 2 to 8% by weight.

As the organopolysiloxane for surface modification, an organopolysiloxane containing multiple bonds, preferably at least one carbon-carbon double and/or triple bond, is used. Without being bound by a particular theory, the inventors of the present invention have the idea that multiple bonds are cross-linked together in UV curing, which has a beneficial effect on the action of the photo-generated radiation.

It is particularly preferred to use a silicone polyether acrylate polymer or a silicone polyether methacrylate polymer. Very particular preference is given to using acrylates and/or methacrylates of hydroxy-functional siloxanes and/or polyalkylene-modified siloxanes. Particular preference is given to using organopolysiloxanes which are obtained by esterification or transesterification of acrylic and/or methacrylic acid or acrylic esters and/or methacrylic esters with hydroxy-functional and/or polyoxyalkylene-modified siloxane derivatives of the general formula (I) in the presence of esterification or transesterification catalysts

Wherein

R¹And/or R⁷＝R²Or [ R ]⁴]_w-[R⁵]_x-[R⁶]_y-R⁸，

R²＝R³Or ≠ R³Represent identical or different alkyl or alkylene groups having from 1 to 24 carbon atoms or optionally substituted phenyl groups having up to 24 carbon atoms,

R⁴is of the formula O, NH, NR²S or a divalent radical of the formula (OSi (CH)₃)₂)_uA group of (1), wherein

u is 1 to 200, and u is,

R⁵alkyl or alkylene radicals having from 1 to 24 carbon atoms which may be the same or different, or

C_nH_2n-fR² _f-R⁴-C_mH_2m-gR² _gWherein

f is 0 to 12, and f is,

g is 0 to 12, and g is,

n is 1 to 18, or a salt thereof,

m is 1 to 18, and m is,

R⁶＝O-(C₂H_4-aR² _aO)_b(C_cH_2cO)_dwherein

a is 0 to 3, and a is,

b is 0 to 100, and b is,

c is 2 to 12, and c is a linear or cyclic,

d is 0 to 100, and,

(b + d) is 1 to 200

And a single polyoxyalkylene segment (C)₂H_4-aR² _aO)_bAnd (C)_cH_2cO)_dThe order of (A) can be arbitrary, and specifically includes block copolymers, such as random polymers, and combinations thereof, or

R⁶＝O_e-C_hH_2h-C_iH_2i-jR⁹ _jWherein

e is 0 or 1, and the total of the two,

h is 0 to 24, and h is,

i is 0 to 24, and i is 0,

j is 1 to 3, and j is equal to,

(w + e) is 0 to 1

And R⁹In each case representing a divalent radical of the formula O, a hydroxyl radical, a radical of the formula C_hH_2hA radical or formula C_kH_2k-1(OH)₁A group of (1), wherein

k is 0 to 24 and

1 to 3 of the total weight of the composition,

R⁸hydrogen radicals or monovalent organic radicals, in which at least one hydrogen radical must be present per molecule when y is equal to 1, or represents OH radicals or monovalent organic radicals, in which at least one OH radical is present per molecule when y is 0,

v is 0 to 200, and v is,

w is 0 or 1, and w is 0 or 1,

x is 0 or 1, and x is a linear or cyclic,

y is 0 or 1, and y is a linear or branched,

z is 0 to 200

And (w + x + y) is 1 to 3

And when z is 0, R¹And/or R⁷Is equal to [ R⁴]_w-[R⁵]_x-[R⁶]_y-R⁸

And when x is 0, then w is also 0,

the person skilled in the art is familiar with the fact that the compounds are present in the form of mixtures which have a distribution which is substantially governed by the laws of statistics. In particular the values of the indices b, d, u, v and z therefore represent mean values.

Examples of siloxane derivatives which can be reacted by the enzyme-catalyzed esterification or transesterification of acrylic acid and/or methacrylic acid or acrylates and/or methacrylates according to the invention are:

the enzymatic esterification or transesterification of acrylic acid and/or methacrylic acid or acrylates and/or methacrylates with the above-mentioned compounds at low temperatures, in particular from 20 to 100 ℃, preferably from 40 to 70 ℃ and mild conditions is advantageous for the following reasons: the lighter color of the product avoids the formation of by-products which might otherwise be derived from, for example, chemical catalysts, uncomplicated removal of the enzyme catalyst from the product, and avoids undesirable and uncontrolled free radical polymerization of acryloyl and/or methacryloyl compounds.

The acryloyl-and/or methacryloyl-functional siloxane derivatives obtainable in this way are characterized in that 5 to 100% of all the initially present hydroxyl groups have reacted to form acrylates and/or methacrylates.

In the case of using esters of acrylic acid and/or methacrylic acid, in particular methyl, ethyl or butyl methacrylate and/or methyl, ethyl or butyl acrylate as donor molecules, acrylation and/or methacrylation is optimally carried out in high yields.

Preferred enzymes which can be used as catalysts are hydrolases, in particular esterases, lipases and proteases. The concrete example is435. The enzymes can be used in pure form or immobilized on a support on which they are chemically or physically bound. The amount of enzyme catalyst is, in particular, from 0.1 to 20% by weight, preferably from 1 to 10% by weight, based on the modified siloxane used. The reaction time depends on the amount and activity of the enzyme catalyst and is, for example, up to 48 hours, preferably up to 24 hours.

In order to achieve a high degree of conversion quickly under simple reaction conditions, it is advantageous to use an excess of at least 10% by weight of acrylic acid or methacrylic acid and/or the corresponding esters thereof (as donor) in the reaction mixture.

The production system may be characterized as a stirred tank reactor or a fixed bed reactor. The stirred tank reactor may be equipped with means for distilling off the alkanol liberated from the acrylic acid and/or methacrylic acid donor or the water liberated from acrylic acid and/or methacrylic acid.

The reaction is preferably carried out until the desired conversion is achieved. The simultaneous distillation process is preferred because removal of the water of reaction or the alkanol of reaction results in higher conversions in shorter reaction times due to shift in the reaction equilibrium.

To achieve the highest possible degree of conversion, it is recommended to remove the water of reaction or the alkanol of reaction.

After the reaction has ended, the enzyme catalyst can be isolated by suitable means, for example by filtration or decantation, and optionally used several times.

The fixed bed reactor is equipped with an immobilized enzyme, wherein the reaction mixture is pumped through a column packed with catalyst. The reaction can also be carried out in an ebullated bed using enzymes immobilized on a support.

The reaction mixture can be continuously pumped through the column, with the flow rate being used to control the residence time and thus the desired conversion. The reaction mixture can also be pumped through the column in a circulating manner, wherein the water of reaction or the alkanol of reaction can also be distilled off simultaneously under vacuum.

Other methods of removing the water of reaction or alkanol of reaction, such as absorption or pervaporation, may also be used.

In a particular embodiment of the invention, the organopolysiloxane is characterized in that it has a polyether excess of 5 to 50% by weight, preferably 5 to 40% by weight, particularly preferably 10 to 30% by weight and very particularly preferably 10 to 20% by weight. These organopolysiloxanes have a particularly advantageous effect on the rheological properties of the coating materials and can likewise be prepared in accordance with the above-described process.

The surface-modified silicas used according to the invention are distinguished in particular by the particular embodimentIn that it will have a refractive index n in comparison with an equivalent UV coating comprising 5% by weight of a reference silica treated with a polyethylene wax_DThe transmittance of a UV curable varnish comprising 5 wt% of the modified silica, 20 ═ 1.4000 to 1.5000, is improved by at least 20%. The transmission is preferably improved by at least 25%, in particular by 30%. The reference silica treated with polyethylene wax is preferably referred to as ACEMATT OK 607, a commercial product of the company Evonik Degussa having specifications according to the product information 12/02, which information is hereby expressly incorporated in the context of the present description. As reference silica, it is also possible to use silica having the same untreated silica and coated with polyethylene wax.

In accordance with the product information 12/02,OK 607 has the following PC data:

table 1:

1) based on the dried material

2) On a burnt matter basis

The values listed in table 1 are averages that may vary around the error limits of the inherent production fluctuations or measurement methods.

In order to detect improved transparency, it is in principle possible to use each UV coating having a refractive index in the abovementioned range, to which the silica according to the invention is added in one case and to which the silica coated with PE wax is added in the other case.

The matting agents used according to the invention can be prepared by a process in which dried silica or a suspension or a filter cake of silica is brought into contact with at least one organopolysiloxane containing at least one multiple bond.

Thus, the present invention includes not only wet coating methods but also dry coating methods.

Preferred methods include at least one of the following steps:

a) the alkali metal silicate solution is reacted with the acidifying agent preferably under alkaline to weakly acidic conditions,

b) optionally further adding an acidifying agent to adjust the pH value of 7 to 2, thereby obtaining a silica suspension,

c) optionally filtering off the precipitated solids and

d) optionally drying the solid by means of prolonged drying, such as a drum dryer or tray dryer, or by means of rapid drying, such as a spray dryer, spin flash dryer, so that the product has a residual humidity of less than 10%,

e) the silica thus obtained is treated with an organopolysiloxane.

In steps a) and b) of the process according to the invention, sodium silicate (waterglass) is preferably used as the aqueous alkali metal silicate solution, having a density of about 1.343kg/l and a weight proportion of 27.3% SiO₂And 7.9% Na₂And O. As acidifying agent, use can be made of every mineral acid, in particular concentrated sulfuric acid (96% H)₂SO₄) Or CO₂。

In step a)

The silicate solution and the acidifying agent can be reacted with one another with stirring, as described, for example, in DE 3144299. The subject matter of the invention is DE 3144299. Optionally, the addition of the acidifying agent or the acidifying agent together with the water glass can be carried out in a water-or sodium silicate stock container. It should preferably be noted that the precipitation is carried out at a pH value which is kept weakly acidic to alkaline. The pH value is especially 6-12. The precipitation can optionally be carried out at a constant pH or a constant base.

In step b)

The pH value in the acidic or neutral range (pH 7 to 2) is preferably adjusted by adding acidifying agents, in particular those already used for precipitation.

In step c)

The silica contained in the suspension can be filtered off, optionally after a waiting time of 0 to 90 minutes, preferably 15 to 60 minutes, and washed to neutrality with deionized water.

In step d)

The solids are preferably dried by means of rapid drying, for example spray dryers, spin flash dryers, or prolonged drying, for example drum dryers or tray dryers, so that the product has a residual humidity of less than 10%.

The surface modification step e) can be carried out in the process described above at various points in time.

In embodiment 1) of the method according to the invention,

0.5 to 30% by weight of the surface-modifying organopolysiloxane is introduced into the silica suspension adjusted to a pH of 7 to 2 in step b). The addition is preferably carried out for a duration of from 1 to 30 minutes, in particular from 5 to 15 minutes, and preferably at the reaction temperature of the reaction in step a), i.e. in particular from 50 to 90 ℃, preferably from 50 to 65 ℃. The surface-modified silica is subsequently filtered off and dried as described for steps c) and d).

In the embodiment 2) of the present invention,

the silica obtained according to steps a) and b) is filtered off as described for step c), optionally washed with deionized water, and thereafter resuspended again with water or sulfuric acid or a mixture of water and sulfuric acid. Subsequently, 0.5 to 30% by weight of the surface-modifying organopolysiloxane is added to the suspension and the suspension thus obtained is sprayed into a spray dryer, so that the surface modification takes place during the drying process. It is furthermore conceivable to introduce the silica suspension and the siloxane simultaneously via a nozzle. Spray drying is carried out at 200-500 ℃ so that the product has a residual humidity of less than 10%. The solids content of the suspension to be sprayed can be up to 25% by weight.

In embodiment 3) of the method according to the invention,

the silica is prepared and dried as described in steps a) -d). The dried silica is then admixed with from 0.5 to 30% by weight of a surface-modifying polymer and thoroughly mixed. The addition of the polymer is carried out in 0 to 120 minutes, preferably in 0 to 60 minutes, most preferably in 0 to 30 minutes. The mixture is mixed continuously for 0-2h at 20-150 ℃. The mixing is preferably carried out at from 20 to 100 ℃ and particularly preferably from 20 to 80 ℃. The mixing process is preferably carried out for 0 to 1h and particularly preferably for 0 to 30 minutes.

Optionally, an emulsification aid, for example LA-S687 (TEGO GmbH) can also be added in the case of embodiments 1) and 2). This is especially true in the case of water-insoluble organosilicon compounds.

In order to achieve the desired particle distribution, it is recommended in embodiments 1 to 3 that the grinding, preferably simultaneous sorting, is carried out after drying of the surface-modified silica. The grinding can be carried out in a commercially available cross-flow mill (e.g., Alpine, Netzsch-Condux).

In order to avoid oversize particles (Oberkorn) or specks (Stippen), it is appropriate to isolate particles having a diameter of more than 50 μm, preferably more than 30 μm, in particular more than 20 μm, after drying the surface-modified precipitated silica or after or during grinding. This can be done, depending on the fineness of the matting agent, for example, by means of a corresponding sieve or a classifier device which can also be integrated into the mill.

In addition to the process variants 1 to 3 described above, the invention also encompasses processes in which the surface modification is carried out in the form of an abrasive coating. The method is characterized in that silica, preferably precipitated silica or fumed silica or a semi-gel or a silica gel, is ground and surface modified simultaneously in a grinding device, preferably a jet mill.

For this purpose, preference is given to using oval tube mills or spiral jet mills with static classification, or alternatively fluidized bed-on-jet mills or dense phase bed jet mills, particularly preferably with dynamic pneumatic classifiers. Very particular preference is given to using jet mills with integrated classifier, such as those described in DE 102006048850. The person skilled in the art knows how such a mill can be operated and the coating agent introduced through the nozzle.

It has proven to be particularly advantageous if the grinding gas has a pressure of 4 bar (absolute) or less and/or a temperature of less than or equal to 180 ℃, preferably less than 100 ℃.

The dry coating process has advantages over the wet coating process described above, in particular when organopolysiloxanes are used, which have a polyether excess of from 5 to 50% by weight, preferably from 5 to 40% by weight, particularly preferably from 10 to 30% by weight and very particularly preferably from 10 to 20% by weight. The polyethers are mostly eluted in the wet coating process. In contrast, polyethers deposit on silica to a large extent up to completely in the dry coating process. Products having different properties are thus obtained, where the products comprising the polyethers according to the invention impart advantageous rheological properties to the coating.

As the surface-modified organopolysiloxane, those described in more detail above can be used.

In the preparation process according to the invention, the addition of the organopolysiloxane is preferably carried out such that the ratio of organopolysiloxane to silica is adjusted to from 0.5 g: 100g to 30 g: 100g, in particular from 2 g: 100g to 20 g: 100g, in particular from 3 g: 100g to 13 g: 100g, during the reaction of the organopolysiloxane with silica.

The surface modification may be performed before, during or after milling or drying as described hereinbefore. The surface-modifying agent can be added here undiluted as pure substance or in diluted form as an aqueous emulsion.

In a particular embodiment, the amount and type of organopolysiloxane are chosen such that the modified silica can impart a refractive index n to an equivalent coating comprising 5% by weight of a reference silica treated with polyethylene wax_DThe transmittance of a UV varnish comprising 5 wt% of this modified silica, 20 ═ 1.4000 to 1.5000, was improved by at least 20%.

UV-curable coatings in the context of the present invention undergo a chemical reaction, preferably within fractions of a second, to become solid after irradiation with UV light. Where a solid and dry film is formed. All UV coating systems or components of UV coating systems known to the person skilled in the art can be used, provided that the organopolysiloxane-modified silicon dioxide described in more detail above is contained as matting agent. Examples of references in which the corresponding compositions can be referred to are:

petry V. (20.04.2004): what is the influence of photoinitiators on matching of UV-cured coatings Fatipec [ editor ] (2004)

BASF AG(1999)：The hart of coatings-Laromer und LucirinRohstoffe für

Meichsner，G.(2003)：Grundlagen der UV-At the following stage: meichsner, G. [ editor ]](2003) Spezielle technology UV lecture manuscript

K.P.Schottenloher：Mattierung vonLacken, HS-Esslingen graduation paper (2004)

The UV curable coating material of the present invention contains a reactive monomer or oligomer as a binder. Preference is given to acrylate or substituted acrylate or unsaturated polyester resins, preferably using epoxy-, polyester-, polyether-, oligoether-or urethane acrylates as binders.

Also copolymers based on acrylates, methacrylates and/or their alkyl (akyl) -substituted derivatives have proven to be particularly suitable as acrylic polymers. These acrylic polymers may thus be, for example, copolymers of acrylic esters with methacrylic esters or copolymers of acrylic esters with alkyl-substituted derivatives of acrylic esters or methacrylic esters. Especially suitable are also copolymers of methyl acrylate and alkyl-substituted derivatives of methacrylic acid esters. Particularly suitable copolymers are, for example, those composed of methyl methacrylate and methyl acrylate (Plex 8671F,GmbH). It goes without saying that mixtures of the copolymers described hereinbefore are also suitable as acrylic polymers for the compositions according to the invention.

In addition to binders and matting agents, the UV coating according to the invention may also comprise auxiliaries, such as photoinitiators, levelling agents, antioxidants, pigments, microcrystalline waxes, organic solvents or water.

Photoinitiators form free radicals and initiate polymerization in the presence of light. As photoinitiator, initiators from the class of α -hydroxyketones or derivatives thereof, preferably hydroxycyclohexyl phenyl ketones, are preferably used in the UV-curable coating according to the invention. These photoinitiators are commercially available, for example, as Irgacure 184, Irgacure 500, Irgacure 2959, or Darocure1173(Ciba Specialty Chemicals, Basel). However, other known photoinitiators may also be selected for the composition according to the invention. For example, alpha-aminoketones, acylphosphine oxides and their respective derivatives are also suitable as such initiators.

The UV-curable composition according to the invention may comprise at least one organic solvent, wherein many solvents generally known for such compositions are considered as solvents, such as terpenes, alkanes, aromatics, alcohols, ketones, esters, ethers or mixtures thereof. The solvent is preferably ethanol, butyl acetate, isopropanol, isobutanol, methoxypropanol, methyl ethyl ketone or mixtures thereof.

The amount of solvent used in the composition can vary freely within the usual limits and is generally adjusted taking into account the rheology and film formation required in the respective application and the venting and drying conditions specific to the application prior to UV curing.

The compositions according to the invention may also comprise at least one levelling additive, for example Byk3510, a polyether-modified polydimethylsiloxane, which may preferably be used in proportions by weight of up to 0.6 to 1.2% by weight.

The UV-curable composition according to the invention may also comprise at least one antifoam additive during the coating process, depending on the respective conditions. Defoamers are typically ionic or nonionic surfactants and can help improve film formation. An exemplary defoamer is Byk 088, a foam breaking polymer in combination with a polysiloxane, used at 0.1 to 0.5 wt.% for reducing or avoiding interfering air inclusions in the coating material.

The UV coating according to the invention comprises preferably from 3 to 30% by weight, preferably from 5 to 20% by weight and very particularly preferably from 8 to 15% by weight of organopolysiloxane-modified silica.

As already indicated above, the surface-modified silicas used in the UV coatings according to the invention and described in more detail above can be used to matt different coating types, for example furniture coatings, graphic coatings, coil coatings, CN coatings.

The physical/chemical data of the precipitated silica according to the invention are determined by the following method:

determination of the coating transmittance

The transmittance was measured using a UV/Vis spectrophotometer Specord 200 from ANALYTIK JENA GmbH, in a 1cm quartz cell at room temperature with air as a reference. The slit width and step size was 2 nm.

For this purpose, the refractive index n is inserted beforehand_D20-1.4000 to 1.5000 UV paint and 2.5g of the corresponding matting agent (surface-modified silica) were added. In this case, the matting agent was dispersed at room temperature at 2000 rpm over a period of 10 minutes into 50g of UV coating using a blade stirrer. The dispersion was carried out at room temperature in a 180ml PE mixing cup. The blade diameter of the stirrer was 43 mm. The freshly prepared dispersion was then filled into a 1cm quartz cell and the UV/Vis spectra were recorded in transmission between 190 and 1100 nm.

DBP absorption

The DBP absorption (DBP value), which is a measure of the absorption capacity of silica, is determined according to standard DIN 53601 as follows:

carrying out the process

12.50g of powdered or pelletized silica having a moisture content of from 0 to 10%, optionally adjusted by drying in a drying oven at 105 ℃, are introduced into the kneader chamber of a Brabender-absorptometer "E" (code 279061). In the case of granules, a sieve size grade (stainless steel sieve from Retsch company) of 3.15 to 1mm was used (by gently pressing the granules through a sieve of 3.15mm pore size with a plastic spatula). Dibutyl phthalate was added dropwise to the mixture at 4ml/min by means of a "Dosimaten Brabender T90/50" with constant mixing (rotational speed of the kneader blades: 125U/min) at room temperature. The mixing process is performed with only low effort and is monitored on the basis of a digital display. Towards the end of the assay the mixture becomes pasty, which is indicated by a rapid increase in the required force. In the case of a display of 600 digits (torque 0.6Nm), both the kneader and the DBP metering device are switched off via electrical contacts. The synchronous motor for the DBP feed is connected to a digital counting mechanism so that the consumption of the DBP can be read in ml meters.

Evaluation of

The DBP absorption is expressed in g/100g and is calculated from the measured DBP consumption by means of the following formula. The density of DBP is usually 1.047g/ml at 20 ℃.

DBP absorption (g/100g) ═ DBP consumption (ml) × DBP density (g/ml) × 100/12.5g

The DBP absorption is defined for dried silica that contains no water. This value is corrected by means of the following correction table in the case of using wet silica. The corrected value corresponding to the water content is added to the experimentally determined DBP value; for example, a water content of 5.8% means a 33g/100g increase in DBP absorption.

Table 2: calibration Table for dibutyl phthalate absorption-Water free-

Determination of the moisture content of silica

According to this method, the volatility ratio of the silica (hereinafter referred to as "humidity" for simplicity) is determined after drying at 105 ℃ for 2 hours according to ISO 787-2. This loss of drying typically consists primarily of moisture.

Carrying out the process

To a dry weighing glass bottle (diameter 8cm, height 3cm) with a ground stopper, 10g of silica in powder, spherical or granular form (starting weight E) are weighed in to the nearest 0.1 mg. The sample was dried in a desiccator at 105. + -. 2 ℃ for 2h in an uncapped state. The weighed glass bottles were then sealed and cooled to room temperature in a desiccator cabinet using silica gel as a desiccant. The final weight a was determined gravimetrically.

The% humidity was determined according to (e), (g) -a (g)% 100%/e (g).

The measurement was performed as a double assay format.

Determination of ignition loss:

2h at 1000 ℃ and, after drying, DIN 55921/3.4, ISO 3262d50

Determination of aggregate size distribution by laser diffraction (Coulter)

The instrument comprises the following steps:

laser diffractometer LS 230, Coulter Corp

Ultrasonic bar Bandelin, model HD 2200, equipped with a DH 13G horn

Cooling bath 80ml

Eppendorf pipette 5ml

Centrifuging the glass bottle, the height is 7cm,

a Petri dish, 4cm in height,

a vacuum bottle with a height of 21cm,

digital thermometer, precision + -0.1K

Chemical products:

ethanol, analytical grade, Merck

Triton X-100, Merck Corp

Sodium hexametaphosphate, Baker Corp

Sample preparation:

the granules were added to a mortar and the coarse granular cake was crushed without grinding. 1g of unaged silica (up to 10 days from the time of preparation) are weighed into a 30ml crimped glass container and 20ml of dispersion solution (20g of sodium hexametaphosphate, filled to 1000ml with demineralized water) are added. The samples were then placed in a cooling bath, which prevented significant heating of the suspension, and sonicated for 1 minute (20W power, 80% pulse). Three samples of dispersion solution were prepared sequentially for each silica. The suspension was placed in a petri dish equipped with a magnetic stirrer to prevent possible sedimentation until sample addition in the fluidic module.

The implementation process comprises the following steps:

the instrument and fluid module were allowed to warm up for at least 30 minutes and the module was automatically flushed (menu bar "control/flush") for 10 minutes before the measurement began.

In the control column of the Coulter software, the opt model is calculated and the refractive index is determined via the menu item "measure" select file window "(real liquid refractive index 1.332; real material refractive index 1.46, imaginary 0.1). The pump speed level was adjusted to 26% and the ultrasound power to 3% in the file window "measurement cycle". The ultrasound items "during specimen addition", "before each measurement" and "during the measurement" are activated.

In addition, the following items are selected in the file window:

offset measurement (1x daily)

Regulating

Background measurement

Regulating the measured concentration

Inputting sample information

Inputting measurement information

Starting double measurement

Automatic flushing

Using PIDS data

After calibration was complete, sample addition was performed. The addition of the dispersed silica was continued until an absorbance of about 45% was reached and the instrument showed OK. The measurements were carried out using the Fraunhofer model, using standard software from Coulter's laser diffractometer LS 230.

Each sample was added and a duplicate measurement for 60 seconds was performed three times. The software calculates the particle size distribution from the raw data curve based on the volume distribution.

Determination of C content

The instrument comprises the following steps:

c-mat 500 from Instruments

Analytical balance

Porcelain boat with cover

Tweezers

Measuring spoon

Reagent

Euro assay control sample 077-2(Instruments Co.) oxygen

Carrying out the process

Measurement of control samples

The control sample is first measured. For this purpose, 0.14-0.18g were weighed on an analytical balance onto a fired and cooled porcelain boat. Since the balance is connected to the "C-mat", the weight is accepted when the start button is operated. The boat must be pushed into the middle of the burner tube within 30 seconds. After the combustion is complete, the measurements are converted to pulses and evaluated by a computer. The measurement was carried out 2 times or more. It may be necessary to readjust the instrument factor. The factor is calculated according to the following formula:

measurement of silica samples

The silica sample is measured after the factor is determined. For this purpose, 0.04 to 0.05g of silicon dioxide were weighed into the porcelain boat in each case and the porcelain boat was covered with a porcelain lid. The silica sample was then measured similarly to the control sample. A third and optionally further measurement is carried out with a deviation > 0.005% and an average value is calculated.

Evaluation of

The carbon content is calculated as follows:

here:

i-pulse

Factor F

E initial weight (g)

Results reporting

The results are reported as% C in 2 decimal places.

Note

The operation of "C-mat 500" can be found inInstructions for Instruments, Inc.

Determination of reflectometer values

1. Foundation

The excellent properties of matt silicas are to influence the reflectivity by purposefully roughening the surface of the coating film. Accordingly, the reflectometer value is an important criterion for characterizing the matt coated film.

2. Principle of

The reflection and thus the gloss properties of the film surface and indirectly its roughness are directly evaluated using this method.

3. Instrument for measuring the position of a moving object

Reflectometers with measurement geometry according to DIN 67530, tested according to DIN 67530 (e.g. haze-gloss, BYK-Instruments).

4. Carrying out the process

The measurement is premised on the fact that the surface of the coating film to be measured is flat, clean, and cured.

The measurements were performed on at least 3 representative locations of the sample. If too large a deviation of the individual measurements is reached, a further measurement should generally be carried out at the representative location or the number of individual measurements should be increased to > 3. For BYK haze-gloss, the standard deviation of the measurement is shown in the display. If the standard deviation s > 0.5, it is recommended to carry out the above measures.

The average is reported in 1 decimal place.

5. Annotation of measurement geometry

In the case of characterizing the matt film surface, it has proven suitable to use 60 ° and 85 ° measurement geometries. Thus, in contrast to DIN 67530, two measurement geometries were used to determine the reflectometry values of the matt coated film surface. Important information about the particle distribution of the matting agent present in the coating film can be obtained by determining the so-called flat gloss (i.e. 85 ° reflectometer value minus 60 ° reflectometer value).

In order to be able to determine the sheen without doubt, the 60 ° reflectometer values of the test specimens to be compared should have a deviation of at most +1.5 reflectometer values.

Determination of rheological Properties

1. Foundation

Silica-based matting agents alter the rheological properties of coatings. This change can be manifested in the construction of non-newtonian flow behavior, such as yield point, structural viscosity effects, and thixotropic effects. These effects can generally be measured with a ball-supported rotational viscometer. In the case where the accuracy of the ball-supported rotational viscometer is insufficient, measurement is performed with an air-cushion rotational viscometer or an oscillation viscometer.

2. Instrument for measuring the position of a moving object

RheolabQC

Measuring cylinder CC 27

Measuring cylinder CC 39

Disposable measuring cup

Control computer and evaluation computer

3. Operating procedures

3.1 measurement System

The coaxial cylinder type measuring system consists of a measuring body, a disposable measuring cup and a measuring cup clamp.

There are 2 different measurement volumes available.

Measuring cylinder (rotating body)	Viscosity range	Amount of filling
			CC 27	Moderate to high viscosity coatings	17ml
CC 39	Low to medium viscosity coatings	65ml

3.2 measurement preparation

The thermostat was switched on and the temperature was measured to be 23 ℃. The cooling device of the thermostat is switched on. The Rheolab QC was turned on and the interior of the Rheolab was checked. The rheology software "rheopolus" on the connected PC was started. The measurement bodies were ligated in RhoelabQC. The self-test of the PC < - > Rheolab QC connection was performed by "measuring instrument", "Start diagnostics". In the normal state, the "standard tool" of the rheolab qc recognizes the measurement volume used independently, displays it on the display of the rheolab qc, and forwards the stored measurement system parameters to the measurement software. The required sample volume corresponding to the measurement volume used is filled without air bubbles into the corresponding disposable measuring cell. The disposable measuring cup (with the outer sleeve) is pushed into the fixture and tightened with a locking nut. The instrument is ready to take measurements according to the instrument instructions.

transparency/Density measurement

In the case of matting agents used in clearcoats, depending on the matting agent and binder system used, more or less pronounced fogging may occur, which gives the clearcoat film a bluish undertone. This effect is therefore also referred to as blue fog. Analytical test data for matting agents do not allow this effect to be inferred. This effect can be detected reproducibly by measurement techniques on correspondingly prepared matt coatings using densitometers or color meters.

By applying the coating film to the black glass sheet, the color depth of the black glass sheet is reduced according to the expression level of the fog. The level of fog expression can be assessed indirectly by measuring the density, i.e., the depth of color through the coating.

1. Instrument for measuring the position of a moving object

Color measuring instrument SpectroEye Gretag Macbeth

2. Operating procedures

2.1 calibration

The instrument has a self-calibrating procedure. This is done immediately after switching on the instrument.

2.2 basic setup

The following settings were selected among the main menu > settings > user-dependent > standard measurements > measurement conditions:

parameter setting

Physical filter has no

White reference absolute (Abs)

Light source type D65

Observation angle 10 °

Density standard DIN

The function "density" is selected in measurement window > measurement function.

The function is switched to "absolute" in the measurement window > absolute/difference.

The function is switched to "number" in measurement window > diagram/number.

Filter "yellow" was selected in the measurement window > density filter.

In the display, Dy shown represents "density measurement with yellow filter".

The number of predetermined values can be used to adjust the automatic average value formation in the measurement window > average value formation.

The yellow filter was selected among the measurement window > density filters.

2.3 measurement

The instrument is adjusted to the "sample" with a rotating wheel over the measurement window. The measurement is started by pressing the measurement button. At least 5 measurements were taken. It should be noted that the measurement site is free of damage, such as craters, inclusions, scratches, bubbles, etc. The maximum allowable deviation between the lowest value and the highest value may be D ═ 0.05. An average value is formed from the determined measurement data (as long as it is not automatically activated).

The following examples are intended to illustrate the invention and should not be construed as limiting the scope of protection as detailed in the claims.

Detailed Description

Example 1:

precipitation method of Evonik Degussa GmbH in an AFG 200 Aeroplex-fluidized bed-pair jet mill from Hosokawa Alpine AGSilicon dioxideHK400 was milled at a milling air inlet temperature of 76 ℃ (milling chamber internal space temperature 60 ℃) and a pressure of 0.4 bar (absolute) and with silicone polyether acrylate from Evonik Goldschmidt GmbHRad 2300 covers. The coating agent is introduced into the mill by means of a nozzle through two-fluid nozzles which are located in the same plane as the milling nozzles (3 milling nozzles at a distance of 120 ° and between two of the milling nozzles at a distance of 60 °). The amount of silicone polyether acrylate was calculated so as to give a carbon content of 3.2 wt.%, based on the total weight of the final product. The product had a d of 4.7 μm₅₀-a value.

Comparative example 1:

example 1, corresponding to DE 102004029069, namely silica which is coated with a matting agent which is polyorganosiloxane which does not contain multiple bonds.

Comparative example 2:

it refers to the commercially available product PQ-Corporation Gasil UV 70C, a flatting agent developed and sold specifically for UV coatings.

Example 2

UV coatings matted with the matting agents described previously were prepared as follows:

formulation of

The individual starting materials were weighed in stepwise fashion in the order described above and homogenized by means of a laboratory dissolver. Homogenization must be carried out in each case after the stages 3 and 4. After level 4 the base varnish was stirred until all solid components were completely dissolved.

Preparation of the matted varnish:

before use, the glossy base paint was homogenized at 2000 rpm with a blade stirrer. In 100 parts by weight of this base paint

a) With the same starting weight (to show the difference in the reflectometry value of the applied matt coating),

b) with different starting weights (in order to obtain the same reflectometer values at a dry film thickness of 15 μm)

c) With different starting weights (in order to determine the achievable reflectometer values at the same viscosity)

The matting agent to be investigated is detected against a corresponding standard sample. After careful incorporation by means of a spatula, the matting agent was dispersed in a 350ml PE beaker for 10 minutes at 2000 rpm with a blade stirrer.

Processing and testing of the prepared matt coating:

after dispersion of the matting agent, it was applied to the BYK test card 2854 with spiral blades of size 20 μm, 40 μm, 60 μm and 80 μm. Double determinations should always be made. After application, the curing of the coating film is carried out in a UV apparatus from the company IST Metz GmbH. It should be noted here that 100% of the power of the Hg lamp is selected, and the belt speed is 2 m/min. The determination of the reflectometer value and the density can be carried out immediately and the determination of the viscosity of the liquid coating material by means of Rheolabs QC only on the following day.

The results of the study are shown in subsequent tables 3 and 4:

Claims

UV coating, characterized in that it contains at least one surface-modified silica, wherein at least part of the silica particles are covered with at least one organopolysiloxane comprising at least one multiple bond, and at least one organopolysiloxane is a silicone polyether acrylate polymer and/or a silicone polyether methacrylate polymer;

wherein the silicone polyether acrylate polymer and/or the silicone polyether methacrylate polymer is an organopolysiloxane obtained by esterification or transesterification of acrylic acid and/or methacrylic acid or an acrylate and/or methacrylate with a hydroxy-functional and/or polyoxyalkylene-modified siloxane derivative of the general formula (I) in the presence of an esterification or transesterification catalytic enzyme,

wherein

R¹And/or R⁷＝R²Or [ R ]⁴]_w-[R⁵]_x-[R⁶]_y-R⁸，

R²＝R³Or ≠ R³Represent identical or different alkyl or alkylene groups having from 1 to 24 carbon atoms or optionally substituted phenyl groups having up to 24 carbon atoms,

R⁴is of the formula O, NH, NR²S or a divalent radical of the formula (OSi (CH)₃)₂)_uA group of (1), wherein

u is 1 to 200, and u is,

R⁵alkyl or alkylene radicals having from 1 to 24 carbon atoms which may be the same or different, or

C_nH_2n-fR² _f-R⁴-C_mH_2m-gR² _gWherein

f is 0 to 12, and f is,

g is 0 to 12, and g is,

n is 1 to 18, or a salt thereof,

m is 1 to 18, and m is,

R⁶＝O-(C₂H_4-aR² _aO)_b(C_cH_2cO)_dwherein

a is 0 to 3, and a is,

b is 0 to 100, and b is,

c is 2 to 12, and c is a linear or cyclic,

d is 0 to 100, and,

(b + d) is 1 to 200

And a single polyoxyalkylene segment (C)₂H_4-aR² _aO)_bAnd (C)_cH_2cO)_dIn an arbitrary order, or

R⁶＝O_e-C_hH_2h-C_iH_2i-jR⁹ _jWherein

e is 0 or 1, and the total of the two,

h is 0 to 24, and h is,

i is 0 to 24, and i is 0,

j is 1 to 3, and j is equal to,

(w + e) is 0 to 1

And R is⁹In each case representing a divalent radical of the formula O, a hydroxyl radical, a radical of the formula C_hH_2hA radical or formula C_kH_2k-1(OH)₁A group of (1), wherein

k is 0 to 24 and

1 is equal to 1 to 3,

R⁸hydrogen radicals or monovalent organic radicals, in which at least one hydrogen radical must be present per molecule when y is equal to 1, or represents OH radicals or monovalent organic radicals, in which at least one OH radical is present per molecule when y is 0,

v is 0 to 200, and v is,

w is 0 or 1, and w is 0 or 1,

x is 0 or 1, and x is a linear or cyclic,

y is 0 or 1, and y is a linear or branched,

z is O to 200

And the sum of (w + x + y) is 1 to 3

And when z is 0, R¹And/or R⁷Is equal to [ R⁴]_w-[R⁵]_x-[R⁶]_y-R⁸

And when x is 0, then w is also 0.
2. UV coating according to claim 1, characterized in that a single polyoxyalkylene segment (C)₂H_4-aR² _aO)_bAnd (C)_cH_2cO)_dThe order of (a) includes block copolymers, or random polymers, or combinations thereof.
3. UV coating according to claim 1, characterized in that the silica means precipitated silica or fumed silica or a semi-gel or a silica gel.
4. UV coating according to claim 1, characterized in that the silica is precipitated silica.
5. UV coating according to any one of claims 1 to 4, characterized in that the surface-modified silica has at least one of the following physico-chemical parameters:

d₅₀：1-50μm，

DBP：100-600g/100g，

c content: 1-20 wt%.
6. UV coating according to claim 5, characterized in that d₅₀Is 1-40 μm.
7. UV coating according to claim 5, characterized in that d₅₀Is 1-30 μm.
8. UV coating according to claim 5, characterized in that d₅₀Is 2-20 μm.
9. UV coating according to claim 5, characterized in that d₅₀Is 3-15 μm.
10. UV coating according to claim 5, characterized in that the DBP is 150-500g/100 g.
11. UV coating according to claim 5, characterized in that the DBP is 200-450g/100 g.
12. UV coating according to claim 5, characterized in that the DBP is 400g/100g of 250-.
13. UV coating according to claim 5, characterized in that the C content is 1 to 10% by weight.
14. UV coating according to claim 5, characterized in that the C content is 2 to 8 wt.%.
15. UV coating according to any one of claims 1 to 14, characterized in that the surface-modified silica imparts a refractive index n_DThe transmittance of a UV coating comprising 5 wt% of the modified surface-modified silica, between 20 and 1.4000 and 1.5000, is improved by at least 20% compared to an equivalent UV coating comprising 5 wt% of a reference silica treated with polyethylene wax.
16. UV coating according to claim 15, characterized in that the reference silica meansOK607。
17. UV coating according to claim 1, characterized in that the polysiloxane has a polyether excess of 5 to 50% by weight.
18. UV coating according to claim 17, characterized in that the polysiloxane has a polyether excess of 5 to 40% by weight.
19. UV coating according to claim 17, characterized in that the polysiloxane has a polyether excess of 10 to 30% by weight.
20. UV coating according to claim 17, characterized in that the polysiloxane has a polyether excess of 10 to 20 wt.%.
21. UV coating according to any one of claims 1 to 20, characterized in that it is a varnish or a lacquer.
22. UV coating according to any one of claims 1 to 21, characterized in that it contains a binder based on reactive monomers or oligomers.
23. UV coating according to claim 22, characterized in that the reactive monomers or oligomers are those of acrylates or substituted acrylates.
24. UV coating according to claim 22, characterized in that the reactive monomer or oligomer is an epoxy-, polyester-, polyether-, oligoether-or urethane acrylate.
25. UV coating according to any one of claims 1 to 24, characterized in that it contains 3 to 30% by weight of silicon dioxide modified with organopolysiloxane and/or at least one component selected from the group consisting of photoinitiators, leveling agents, antioxidants, pigments, microcrystalline waxes, organic solvents and water.
26. UV coating according to claim 25, characterized in that it contains 5 to 20% by weight of silicon dioxide modified with organopolysiloxane and/or at least one component selected from the group consisting of photoinitiators, levelling agents, antioxidants, pigments, microcrystalline waxes, organic solvents and water.
27. UV coating according to claim 25, characterized in that it contains 8 to 15 wt. -% of silicon dioxide modified with organopolysiloxane and/or at least one component selected from the group consisting of photoinitiators, levelling agents, antioxidants, pigments, microcrystalline waxes, organic solvents and water.
28. A method for preparing a surface-modified silica as defined in any one of claims 1 to 27, characterized in that dried silica or a suspension or a filter cake of silica is contacted with at least one organopolysiloxane comprising at least one multiple bond, wherein the at least one organopolysiloxane is a silicone polyether acrylate polymer and/or a silicone polyether methacrylate polymer as defined in any one of claims 1 to 27.
29. Method according to claim 28, characterized in that it comprises at least one of the following steps:

a) reacting an alkali metal silicate solution with an acidifying agent,

b) further adding an acidifying agent to adjust the pH value of 7 to 2, thereby obtaining a silica suspension,

c) filtering off the precipitated solid and

d) drying the solid by means of prolonged drying or by means of flash drying, so that the product has a residual humidity of less than 10%,

e) the silica thus obtained is treated with at least one organopolysiloxane comprising at least one multiple bond.
30. The process according to claim 29, characterized in that in step a) the alkali metal silicate solution is reacted with the acidifying agent under alkaline to weakly acidic conditions.
31. The process according to claim 29, characterized in that the solids are dried in step d) by means of a drum dryer or a tray dryer.
32. The process according to claim 29, characterized in that the solids are dried in step d) by means of a spray dryer or a spin flash dryer.
33. The method according to claim 28, characterized in that 0.5-30 wt. -% of the surface-modifying polysiloxane as defined in any one of claims 1-27 is added.
34. A process according to any one of claims 29 to 33, characterised in that the silica filtered out and optionally washed with deionized water according to step c) is resuspended with water or sulphuric acid or a mixture of water and sulphuric acid, whereafter the surface-modifying organopolysiloxane as defined in any one of claims 1 to 27 is added to the suspension, and the suspension thus obtained is dried.
35. A method according to claim 34, characterized in that the obtained suspension is spray-dried.
36. The method according to claim 34, characterized in that the obtained suspension is dried so that the product has a residual humidity of less than 10% by weight.
37. The method according to any one of claims 29 to 33, characterized in that the surface-modifying organopolysiloxane according to any one of claims 1 to 27 is incorporated into the silica after step d) and is mixed thoroughly.
38. The method of claim 37, wherein the mixing is continued for 0 to 120 minutes.
39. Method according to claim 37 or 38, characterized in that the silica and the organopolysiloxane are mixed for a further 0-2h and/or subjected to a heat treatment at 20 to 150 ℃.
40. A method according to any one of claims 28 to 39, characterized in that the drying of the surface-modified silica is followed by grinding and/or separation of particles having a diameter of more than 50 μm.
41. The method according to claim 28, characterized in that the silica is ground and surface modified simultaneously in the grinding device.
42. A process according to claim 41, characterized in that the silica is precipitated or fumed silica or a semi-gel or a silica gel.
43. The method of claim 41, wherein the milling device is a jet mill.
44. The method as claimed in any of claims 41 to 43, characterized in that the grinding gas has a pressure of ≤ 4 bar (absolute) and/or a temperature of less than or equal to 180 ℃.
45. The method of claim 44, wherein the milling gas has a temperature of less than 100 ℃.
46. A method for preparing a UV coating, characterized in that it comprises the method steps as defined in any one of claims 28 to 45.
47. A process according to claim 46, characterized in that the organopolysiloxane-modified silica as defined in any one of claims 1 to 27 or prepared according to the process of any one of claims 28 to 45 is incorporated into a UV coating composition.