Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
  • C09C1/30—Silicic acid
  • C09C1/3009—Physical treatment, e.g. grinding; treatment with ultrasonic vibrations
  • C09C1/3018—Grinding
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
  • C09C1/30—Silicic acid
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/11—Powder tap density
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/19—Oil-absorption capacity, e.g. DBP values

Definitions

• the invention relates to coating systems.
• a dispersion of fumed silica characterized in that it comprises a structurally modified silanized silica and a solvent for the preparation of coating materials which are characterized in that the coating materials, in addition to a relatively high scratch resistance, exhibit less of an unwanted haze or an unwanted frosting (WO 2007/128636) .
• the known methods of incorporating fumed silica into the coating system have the disadvantage that the clearcoat materials produced in this way exhibit inadequate brightness of colour, measured on the basis of the black number My (also called Jetness, Technical Information No. 1204, Degussa AG) .
• the object was therefore to develop a process allowing the fumed silica, with easy dispersibility, to be incorporated into coating systems in such a way that the coating materials exhibit not only improved scratch resistance but also high brilliance of colour, measured on the basis of the black number My.
• the invention provides coating systems characterized in that they contain 0.5% by weight to 30% by weight of a hydrophilic, structurally modified and optionally reground, fumed silica.
• the structurally modified, hydrophilic, fumed silica used in accordance with the invention can have a tamped density of 100 to 250 g/1.
• the structurally modified silica used in accordance with the invention can have a DBP number of 160 to 240 g/100 g (DIN 53601) .
• the structurally modified silica used in accordance with the invention can have a DBP number of 180 to 250.
• the water content not only of the silica starting material used but also of the structurally modified silicas used in accordance with the invention can be less than 1.5% by weight.
• the reground, structurally modified silicas used in accordance with the invention can have a grindometer value of less than/equal to 60 ⁇ m, preferably less than/equal to 40 ⁇ m.
• the structurally modified silica used in accordance with the invention can have a water content which is higher than that of the silica starting materials used. It can be not more than 3.5% by weight.
• a process for preparing the hydrophilic fumed silica used in accordance with the invention can be characterized in that hydrophilic fumed silica is structurally modified and optionally reground.
• the structural modification is carried out by means of a ball mill, or of a continuously operating ball mill.
• water can be added to the silica. This addition may be made in an amount of 0.5% to 5% by weight, preferably 0.5% to 2% by weight. It results in a lower thickening effect.
• the DBP number is lower or cannot be ascertained.
• the structural modification raises the grindometer value (particle size limit) .
• the increased grindometer value is lowered again during regrinding.
• Figure 1 shows the original fumed silica
• Figure 2 represents the structurally modified fumed silica
• the structurally modified fumed silica has a higher tamped density.
• the individual aggregates remaining are more spherical. They can have a thickening effect of ⁇ 1400.
• the thickening effect can be ⁇ 1000.
• the thickening effect may be ⁇ 1400.
• Regrinding reduces the grindometer value, with the particle size distribution being shifted towards smaller particles.
• the structure of the fumed silica that has remained after structural modification is not adversely affected by regrinding .
• Regrinding has virtually no effect on the performance properties of the structurally modified, fumed silica, since the energy input for regrinding is lower than in the ball mill .
• regrinding it is possible, for example, to use the following apparatus: air-jet mill, toothed-disc mill or pinned-disc mill. More preferably an air-jet mill can be used.
• a heat treatment may be carried out. This heat treatment may take place batchwise, in a drying cabinet for example, or continuously, in a fluid bed or fluidized bed, for example.
• hydrophilic fumed silicas it is possible to use hydrophilic fumed silicas which have a BET surface area of 50 ⁇ 30 to 380 ⁇ 30 m 2 /g. With particular preference it is possible to use hydrophilic fumed silicas which have a BET surface area of 200 ⁇ 25 or 300 ⁇ 30 m 2 /g.
• hydrophilic fumed silica Aerosil® 200 and the hydrophilic fumed silica Aerosil® 300 are structurally modified using a ball mill. In this case, as indicated in Table 2, water is added and regrinding takes place.
• the structurally modified silicas obtained have a higher loss on drying than the initial silica.
• Table 3 shows the effects of structural modification and of regrinding on the hydrophilic fumed silicas AEROSIL® 200 and AEROSIL® 300.
• AEROSIL® 200 in the untreated state possesses a surface area of 202 m 2 /g. This is not influenced or changed by the structural modification and regrinding (see Comparative Example 1 and also Examples 1 to 6) .
• the tamped density is increased as a result of the structural modification.
• the subsequent regrinding however, lowers the tamped density again (see Examples 5 and 6) .
• the DBP number is lowered by the structural modification. It remains, however, unaffected by the regrinding.
• the grindometer value is raised by the structural modification and returned to the original value by the regrinding, if the air-jet mill is used for regrinding.
• the thickening effect of the hydrophilic fumed silica is lowered significantly by the structural modification, but increases somewhat as a result of the regrinding.
• the degree of dispersion determines the performance properties of the liquid thickened with Aerosil.
• the measurement of the grindometer value serves for assessing the degree of dispersion.
• the grindometer value is meant the boundary layer thickness below which the bits or aggregates present become visible on the surface of the sample which has been coated out.
• the sample is coated out in a groove with a scraper, the depth of the groove at one end being twice the size of the diameter of the largest Aerosil particles, and decreasing steadily down to 0 at the other end.
• the depth value is read off, in micrometres, the value in question being that below which a relatively large number of Aerosil particles become visible as a result of bits or scratches on the surface of the binder system.
• the value read off is the grindometer value of the system present.
• the testing instructions run as follows: Apparatus and reagents:
• Dispermat AE02-C1 VMA-Getzmann (dispersing disc, diameter 5 cm) plastic beaker, 350 ml, external diameter 8.4 cm plastic lid to fit
• mixtures of hydrophilic AEROSIL® grades and unsaturated polyester resins are prepared, in order to characterize the granularity and the thickening capacity of the silicas.
• Resins e.g. polyester resin, UP resin, vinyl ester resin
• Resins generally contain fillers for the purpose of improving the performance properties.
• the nature and concentration of the filler used influence the rheological behaviour of the resin.
• a Brookfield DV III rheometer is used. Using a spatula, the mixture is homogenized in its storage vessel for 1 minute. In the course of this homogenization no bubbles ought to form. Subsequently the mixture is introduced into a 180 ml beaker until the beaker is almost full. Without delay, the measuring head of the rheometer is immersed fully into the mixture, and measurement takes place as follows: 5 rpm value read off after 60 s 50 rpm value read off after 30 s
• the values read off are the viscosities [Pa*s] at the respective rpm.
• a Hegmann grindometer block is used.
• the grindometer block is placed on a flat, slip-proof surface and is wiped clean immediately prior to testing.
• a bubble-free sample is then introduced at the deepest point of the groove in such a way that it flows off somewhat over the edge of the groove.
• the scraper is then held in both hands and placed, perpendicularly to the grindometer block and at right angles to its longitudinal edge, with gentle pressure, onto the low end of the groove.
• the sample is then coated out in the groove by means of slow, uniform drawing of the scraper over the block. The granularity is read off not later than 3 seconds after the sample has been scraped.
• the surface of the sample is viewed obliquely from above (at an angle of 20-30° to the surface) transversely to the groove.
• the block is held to the light in such a way that the surface structure of the sample is readily apparent.
• the value found as granularity on the scale is the figure in micrometres below which a relatively large number of silica grains become visible as bits or scratches on the surface. Individual bits or scratches occurring randomly are not taken into account in this context .
• the granularity is assessed at least twice, in each case on a dispersion which has been newly coated out.
• A grindometer value in micrometres
• B grindometer value in Hegmann units
• C grindometer value in FSPT units
• dispersion was carried out using a bead mill.
• the examples below show the effect of grinding on the structurally modified hydrophilic silicas.
• dispersion was carried out for 60 minutes using a Skandex disperser, in 500 ml glass bottles with addition of 400 g of glass beads (3 mm in diameter) .
• the coatings properties are not notably affected in the case of grinding in accordance with version /1; it is therefore surprising that the process /2 significantly improves the grindometer value and the haze in the case of the AEROSIL 200 and the AEROSIL 300 variant.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Inorganic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Paints Or Removers (AREA)
• Silicon Compounds (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)

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• 2007
  • 2007-12-11 EP EP07122862A patent/EP2070992A1/de not_active Withdrawn
• 2008
  • 2008-11-20 US US12/741,393 patent/US8038788B2/en not_active Expired - Fee Related
  • 2008-11-20 JP JP2010537362A patent/JP5661469B2/ja not_active Expired - Fee Related
  • 2008-11-20 WO PCT/EP2008/065912 patent/WO2009074438A1/en not_active Ceased
  • 2008-11-20 KR KR1020107012796A patent/KR20100106372A/ko not_active Withdrawn
  • 2008-11-20 CN CN200880120231.9A patent/CN101896557B/zh not_active Expired - Fee Related

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