FIELD OF THE INVENTION

The present invention relates to a coating, which comprises at least one po- rous pigment and a binder providing opacity and/or gloss. The invention relates also to a coating composition, which comprises a first coating comprising at least one porous pigment and a binder providing opacity and/or gloss and a second coating comprising a binder providing opacity and/or gloss. The coating composition option- ally comprises a third coating comprising a binder, which provides gloss. The inven- tion also relates to the use of such a coating and coating composition as a titanium dioxide substitute without impairment of the optical properties. The invention relates also to a method for preparing the coating composition of the invention.

BACKGROUND OF THE INVENTION

Titanium dioxide (T1O2) is commonly used as a white pigment in paints, fillers of paper, carton, plastic, rubber, laminate and printing inks as well as in different kinds of coatings. The most important properties achived by the use of titanium di- oxide are opacity, coverage, brightness, tintability and L-value. T1O2 is the most ef- fective and very expensive pigment providing optical properties. White titanium di- oxide is commercially available as anatase crystals and rutile crystals. Both anatase and rutile crystals are non-amorphous and widely commercially available. There are also amorphous forms of T1O2 but these are not commercially widely available.

Because T1O2 is expensive, so-called extenders are typically added to titanium dioxide to substitute part of the required amount of titanium dioxide. Extenders are pigments or fillers, which are substantially cheaper than titanium dioxide and which can be used to separate physically the crystals of titanium dioxide from each other and have the distances of the crystals more fitted for the light scattering.

The amount of extenders should, however, be kept low, since the high refrac- tive index of T1O2 (about 2.49 - 2.61 ) gives finally the highest light scattering effi ciency and bigger amounts of extenders diminish the light scattering efficiency. Re- garding their optical properties, such as opacity, brightness, shade, hiding power, the extenders are at their best when their average particle size is in the range of about half of wavelength of light. Typically, at most 25% by weight of titanium dioxide can be replaced in different applications without losing the optical properties ach- vieved with titanium dioxide, espcially opacity. In addition, the producers of titanium dioxide commonly coat titanium dioxide with different organic and/inorganic precip- itation or polymer products of chemicals in an amount of 1 -20% based on the weight of the pigment.

Patent publication WO 2009/109705 (FP-Pigments Oy) discloses replacing ti- tanium dioxide partly with calcium carbonate. Patent publication WO 2015/007954 (FP-Pigments Oy) discloses compositions comprising titanium dioxide and addi- tives, which can be used for substitution of at least part of the titanium dioxide in said composition. The first additive comprises a composite pigment, which corn- prises a shell-forming component and an optical pigment, and a second additive comprises a reactive polymer. The shell-forming component is preferably an inor- ganic compound having a low water solubility, such as precipitated calcium car- bonate, calcium sulphate, barium sulphate, magnesium carbonate, magnesium sili cate, aluminium hydroxide or aluminium silicate.

BRIEF DESCRIPTION OF THE INVENTION

An object of the present invention is to provide a coating, which comprises at least one porous pigment and a binder providing opacity and/or gloss. An object of the present invention is to provide a coating composition, which comprises a first coating comprising at least one porous pigment and a binder providing opacity and/or gloss and a second coating comprising a binder providing opacity and/or gloss. The coating composition optionally comprises a third coating comprising a binder, which provides gloss. The second coating of the coating composition is es- sentially pigment free. The third coating of the coating composition is essentially pigment free.

The coating of the invention is suited to be used as a substitute for fillers of paper, carton, plastic, rubber and laminate. The coating of the invention is suited to be used as a coating for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. An object of the present invention is to provide a coating comprising at least one pigment and a binder providing opac- ity and/or gloss for use as a pigment coating, which provides opacity and brightness.

Further, an object of the present invention is the use of the coating comprising at least one porous pigment and a binder providing opacity and/or gloss as a tita- nium dioxide substitute without impairment of the optical properties.

The coating composition of the invention is suited to be used as a substitute for fillers of paper, carton, plastic, rubber and laminate. The coating composition of the invention is suited to be used as a coating for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints.

An object of the present invention is to provide a coating composition compris- ing a first coating, which comprises at least one porous pigment and a binder provid- ing opacity and/or gloss and a second coating which comprises a binder providing opacity and/or gloss for use as a coating, which provides opacity and brightness.

Further, an object of the present invention is the use of the coating composition as a titanium dioxide substitute without impairment of the optical properties.

An object of the invention is also a method for preparing the coating composi- tion of the invention.

The objects of the invention are achieved by the products the uses and the method characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to a coating comprising at least one porous pigment and a binder providing opacity and/or gloss. Especially the invention is directed to a coating comprising at least one porous pigment and a binder providing opacity and/or gloss, wherein the pigment is selected from: a) precipitated aluminium silicates, calcium silicates, magnesium silicates, al- uminium magnesium silicates, aluminium calcium silicates, aluminium calcium mag- nesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, cal- cium magnesium silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, a combination/mix- ture of any other aluminium, magnesium, calcium and/or zinc silicate, silicas or any mixture thereof, wherein the precipitated pigment does not contain titanium dioxide, b) precipitated composite pigments, which comprise titanium dioxide and alu- minium silicates, calcium silicates, magnesium silicates, aluminium magnesium sil- icates, aluminium calcium silicates, aluminium calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium sili- cates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicates, a combination/mixture of any other alu- minium, magnesium, calcium and/or zinc silicate, silicas or any mixture thereof, c) composite pigments, which comprise titanium dioxide and modified calcium carbonate (MCC).

In one embodiment of the invention, the coating comprises a binder providing opacity and/or gloss and one porous pigment, which is selected from: a) precipitated aluminium silicates, calcium silicates, magnesium silicates, al- uminium magnesium silicates, aluminium calcium silicates, aluminium calcium mag- nesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, cal- cium magnesium silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, magnesium zinc sil- icates, calcium magnesium zinc silicates, silicas or any mixture thereof, wherein precipitated pigment does not contain titanium dioxide, b) precipitated composite pigments, which comprise titanium dioxide and alu- minium silicates, calcium silicates, magnesium silicates, aluminium magnesium sili cates, aluminium calcium silicates, aluminium calcium magnesium silicates, zinc sil- icates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, alu- minium magnesium zinc silicates, a combination/mixture of any other aluminium, magnesium, calcium and/or zinc silicate, silicas or any mixture thereof. c) composite pigments, which comprise titanium dioxide and modified calcium carbonate (MCC), wherein the coating does not contain other pigments. In one em- bodiment, the precipitated pigment is selected from aluminium silicates, aluminium magnesium silicates, aluminium calcium silicates, aluminium calcium magnesium silicates, calcium magnesium silicates, zinc silicates, aluminium zinc silicates, cal- cium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, calcium magnesium zinc sili cates and silicas. In one embodiment, the precipitated pigment is selected from al- uminium magnesium silicates, aluminium calcium silicates, aluminium calcium mag- nesium silicates and calcium magnesium silicates. In one embodiment, the precipi tated pigment is selected from zinc silicates, aluminium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicates. In one embodiment, the precipitated pigment is selected from silicas.

In one embodiment of the invention, the precipiated pigments do not essen- tially contain titanium dioxide. In one embodiment of the invention, the precipitated pigments do not contain titanium dioxide, i.e., the precipitated pigments are T1O2- free.

In one embodiment, the composite pigment comprises titanium dioxide and at least one precipitated pigment, which is selected from aluminium silicates, alumin- ium magnesium silicates, aluminium calcium silicates, aluminium calcium magne- sium silicates, calcium magnesium silicates, calcium silicates, zinc silicates, alumin- ium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, calcium magnesium zinc silicates and silicas. In one embodiment, the composite pigment comprises titanium dioxide and at least one precipitated pigment, which is selected from aluminium magnesium silicates, aluminium calcium silicates, aluminium cal- cium magnesium silicates and calcium magnesium silicates. In one embodiment, the composite pigment comprises titanium dioxide and at least one precipitated pig- ment, which is selected from zinc silicates, aluminium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicates. In one embodiment, the composite pig ment comprises titanium dioxide and at least one precipitated pigment, which is se- lected from silicas. In one embodiment of the invention, the composite pigment con- tains at least one of the precipitated pigments disclosed above and at most 50% by weight of titanium dioxide based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 50% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 30% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 15% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 10% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 5% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 5-50% by weight based on the weight of the com- posite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 10-50% by weight based on the weight of the composite pig- ment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 15-50% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 15-30% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment does not contain polymers as additives. In one embodiment, the composite pigment does not contain any shell structures.

In one embodiment of the invention, the precipited pigments and/or composite pigments may optionally contain also Na-, K-, L-, S0 ₄ -, SO3-, P0 ₄ -, BO3-, B-, PO3-, NO ₂ -, NO3-, F-, carbonic acid-, carboxylic acid-, zinc-, manganese-, iron-, zirkonium- , nickel-, cobolt-, chrome-, barium-, sulphur-, strontium-, carbon-, Cl- residues and/or residues of other elements.

In one embodiment of the invention, the precipited pigments and/or composite pigments may optionally contain also stabilizing agents, dispersing agents, surfac- tants and/or other conventional additives.

In one embodiment of the invention, the porous pigment refers to a pigment, which has a BET-value higher than 15 m ² /g. In one embodiment of the invention, the porous pigment has a BET-value higher than 50 m ² /g.

The particles of the porous pigment and/or composite pigment of the invention are aggregates, which have a cluster-type formation made up of primary/ultimate particles. Aggregates have a definite pattern of molecules formed of primary (ele- mental) particles by an irreversible process and they cannot be broken by mechan- ical forces. As a result of the process, the specific surface area of an aggregate is smaller than the sum of its primary particles. Agglomerates consist of primary parti cles and/or aggregates which are joined loosely together e.g. at the corners or edges and can be broken by mechanical forces. Thus agglomerates can change their size and shape.

The average particle size of the porous pigment and/or composite pigment of the invention is at most 100 pm, determined by laser measurement In one embodi- ment, the average particle size of the porous pigment and/or composite pigment of the invention is at most 10 pm (0-10 pm), determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is below 10 pm, determined by laser measurement. In one em- bodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-10 pm or in the range of 0.2-10 pm, de- termined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 1 - 10 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention is at most 5 pm (0-5 pm), deter- mined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention is below 5 pm, deter- mined by laser measurement. In one embodiment of the invention, the average par- ticle size of the porous pigment and/or composite pigment is in the range of 0.1-5 pm or in the range of 0.2-5 pm, determined by laser measurement. In one embodi- ment of the invention, the average particle size of the porous pigment and/or com- posite pigment is in the range of 1-5 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pig- ment of the invention is at most 2 pm (0-2 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or compo- site pigment of the invention is below 2 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-2 pm or in the range of 0.2-2 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 1 - 2 pm, determined by laser measurement. In one embodiment of the invention. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the inven- tion is at most 1 pm (0-1 pm), determined by laser measurement. In one embodi- ment, the average particle size of the porous pigment and/or composite pigment of the invention is below 1 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-1 pm or in the range of 0.2-1 pm determined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 0.1-0.6 pm or 0.2-0.6 pm, determined by la- ser measurement.

In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention after precipitation and before any grinding is at most 10 pm (0-10 pm). In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention after precipitation and before any grinding is below 10 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment after the precipitation and before grinding is in the range of in the range of 0.1-10 pm, 0.2-10 pm or 1-10 pm, determined by laser measurement. In one em- bodiment, the average particle size of the porous pigment and/or composite pigment of the invention after the precipitation and before grinding is at most 5 pm (0-5 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigement and/or composite pigment of the invention after the precipita tion and before grinding is below 5 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigement and/or composite pigment after the precipitation and before grinding is in the range of in the range of 0.1 -5 pm, 0.2-5 pm or 1 -5 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or compo- site pigment after the precipitation and before grinding is at most 2 pm (0-2 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is below 2 pm, determined by laser measurement. In one embodiment of the inven- tion, the average particle size of the poeous pigment and/or composite pigment after precipitation and before grinding is in the range of 0.1-2 pm, 0.2-2 pm or 1-2 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is at most 1 pm (0-1 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after pre- cipitation and before grinding is below 1 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is in the range of 0.1-1 pm or 0.2-1 pm determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigement and/or composite pig- ment after precipitation and before grinding is in the range of 0.1-0.6 pm or 0.2-0.6 pm, determined by laser measurement.

In one embodiment of the invention, the average particle size and/or the parti- cle size distribution of the pigment and/or composite pigment is determined by laser diffraction technique. In one embodiment of the invention, the average particle size and/or the particle size distribution of the pigment and/or composite pigment is de- termined by laser diffraction technique using equipment, which is able to determine particle sizes in the range of 0.02 - 2000 pm. In one embodiment of the invention, the average particle size and/or the particle size distribution of the pigment and/or composite pigment is determined with Malvern 2000-analyzer. In one embodiment of the invention, the pore volume of the pigment is typically in the range of 0.20 - 0.30 cm ³ /g. In one embodiment of the invention, the pore volume of the composite pigment is typically in the range of 0.15 - 0.20 cm ³ /g.

In one embodiment of the invention, the air pores of the precipitated pigments are kept empty after the drying, wherein the difference between the refractive index of the air in the pores (about 1 ) and the refractive index of the pigment (1 .4-1 .8) can be utilized as light scattering, which is shown as better opacity and brightness.

In one embodiment of the invention, the coating comprises a binder providing opacity and/or brightness and at least one porous pigment, which is selected from composite pigments comprising titanium dioxide and modified calcium carbonate (MCC). In one embodiment of the invention, the Ti0 ₂ -calcium carbonate composite pigment is prepared by allowing titanium dioxide T1O2, calcium hydroxide Ca(OH)2 and carbon dioxide CO2 to react with each other and treating the obtained T1O2- precipitated calcium carbonated composition with acid, such as sulphuric acid, H2S0 ₄ , for example, wherein the surface of the precipitated calcium carbonate is corroded porous by the acid. Modified calcium carbonates (MCC) can be prepared from ground calcium carbonate (GCC) by corroding with acids. Marble and lime- stone are conceivable raw materials for ground calcium carbonate (GCC). MCCs work well in mat coatings, but not due to the porosity in glossy coatings.

The coating of the invention comprises also a binder, which provides opacity and/or gloss, which binder is selected according to the purpose of use of the coating. In one embodiment of the invention, the binder is a binder providing opacity and gloss. In one embodiment of the invention, the binder is a binder providing gloss. In one embodiment of the invention, the binder is a binder providing opacity. It is inte- gral to the binder providing opacity that it increases the coverage of the coating. For example, hollow air containing structures represent a technique, which generates coverage in binders.

The coating of the invention is suited to be used as a substitute for fillers of paper, carton, plastic and rubber and as a coating for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. Different types of binders providing opacity and/or gloss are available commercially and a person skilled in the art selects the binder providing opacity and/or gloss ac- cording to the purpose of use of the coating. In one embodiment of the invention, the binder is suited to be used in substitutes for fillers of paper, carton, plastic and rubber. In one embodiment of the invention, the binder is suited to be used in coat- ings of paper, carton, plastic, rubber, laminate, concrete and wood. In one embodi- ment of the invention, the binder is suited to be used in paints, especially in multi layer paints. Suitable binders generally used in paints, for example, are different acryl-, alkyd-, latex-, and epoxypolymer based compounds or polyvinylalcohol- and polyurethane based compounds, among others. Other suitable binders are synthetic or natural polymers, which are based on vinylacetate, vinylethylene (VAE), polyure- thane, polyester, melamine resins, silanes, siloxanes or oils, among others. Exam- pies of binders, used among others in paints, are ROPAQUE™ Ultra E-polymer (The Dow Chemical Company) which provides coverage (opacity) and shade (brightness), but does not provide gloss, and Acronal ^® S 728-polymer (BASF Cor- poration), which provides gloss.

The coating of the invention comprises 0-30% binder based on the weight of the pigment-binder composition or the composite pigment-binder composition. In one embodiment, the coating of the invention comprises 1 -30% binder based on the weight of the pigment-binder composition or the composite pigment-binder compo- sition. In one embodiment, the coating of the invention comprises 1 -20% binder based on the weight of the pigment-binder composition or the composite pigment- binder composition. In one embodiment, the coating of the invention comprises 1 - 10% binder based on the weight of the pigment-binder composition or the composite pigment-binder composition. In one embodiment of the invention, the coating corn- prises 3-10% binder based on the weight of the pigment-binder composition or the composite pigment-binder composition. In one embodiment of the invention, the coating comprises 4-6% binder based on the weight of the pigment-binder compo- sition or the composite pigment-binder composition. In one embodiment of the in- vention, the coating comprises about 5% binder based on the weight of the pigment- binder composition or the composite pigment-binder composition.

In one embodiment of the invention, the pigment:binder-ratio and/or the com- posite pigment:binder-ratio is in the range of 70-100:30:0. In one embodiment of the invention, the pigment:binder-ratio and/or the composite pigment:binder-ratio is in the range of 70-99:30-1 . In one embodiment of the invention, the pigmentbinder- ratio and/or the composite pigment:binder-ratio is in the range of 80-99:20-1 . In one embodiment of the invention, the pigment:binder-ratio and/or the composite pig- ment:binder-ratio is in the range of 90-99:10-1 . In one embodiment of the invention, the pigment:binder-ratio and/or the composite pigment:binder-ratio is in the range of 90-97:10-3. In one embodiment of the invention, the pigment:binder-ratio and/or the composite pigment:binder-ratio is in the range of 94-96:6-4. In one embodiment of the invention, the pigment:binder-ratio and/or the composite pigment:binder-ratio is 95:5.

In one embodiment, the coating of the invention is a dry coating. The coating of the present invention is suitable for use as a substitute for fillers of paper, carton, plastic, rubber and laminate. The coating of the invention is suitable for use in coatings for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. The coating of the invention is suitable for use as a pigment coating providing opacity and brightness. The coating of the invention is suitable for use as a titanium dioxide substitute without impairment of the optical properties of the product to be produced.

The invention relates also to a coating composition comprising a first coating, which comprises at least one precipitated porous pigment and a binder providing opacity and/or gloss and a second coating, which comprises a binder providing opacity and/or gloss. The coating composition of the invention optionally comprises a third coating, which comprises a binder providing gloss.

The second and/or the third coating of the coating composition are essentially pigment-free. In one embodiment of the invention, the second coating of the coating composition is essentially pigment-free. In one embodiment of the invention, the second coating of the coating composition is pigment-free. In one embodiment of the invention, the third coating of the coating composition is essentially pigment- free. In one embodiment of the invention, the third coating of the coating composition is pigment-free.

The first coating of the coating composition of the invention comprises at least one porous pigment, which is selected from: a) precipitated aluminium silicates, calcium silicates, magnesium silicates, al- uminium magnesium silicates, aluminium calcium silicates, aluminium calcium mag- nesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, cal- cium magnesium silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, a combination/mix- ture of any other aluminium, magnesium, calcium and/or zinc silicate, silicas or any mixture thereof, wherein the precipitated pigment does not contain titanium dioxide, b) precipitated composite pigments, which comprise titanium dioxide and alu- minium silicates, calcium silicates, magnesium silicates, aluminium magnesium sil- icates, aluminium calcium silicates, aluminium calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium sili- cates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicates, a combination/mixture of any other alu- minium, magnesium, calcium and/or zinc silicate, silicas or any mixture thereof, c) composite pigments, which comprise titanium dioxide and modified calcium carbonate (MCC).

In one embodiment of the invention, the first coating of the coating composition comprises one porous pigment, which is selected from: a) precipitated aluminium silicates, calcium silicates, magnesium silicates, al- uminium magnesium silicates, aluminium calcium silicates, aluminium calcium mag- nesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, cal- cium magnesium silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates, magnesium zinc sil- icates, calcium magnesium zinc silicates, silicas or any mixture thereof, wherein the precipitated pigment does not contain titanium dioxide, b) precipitated composite pigments, which comprise titanium dioxide and alu- minium silicates, calcium silicates, magnesium silicates, aluminium magnesium sil- icates, aluminium calcium silicates, aluminium calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium sili- cates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicatesmagnesium zinc silicates, calcium mag- nesium zinc silicates, silicas or any mixture thereof, c) composite pigements, which comprise titanium dioxide and modified cal- cium carbonate (MCC), wherein the first coating does not contain other pigments.

In one embodiment of the invention, the first coating of the coating composition comprises at least one porous pigment, which is selected from aluminium silicates, calcium silicates, magnesium silicates, aluminium magnesium silicates, aluminium calcium silicates, aluminium calcium magnesium silicates, silicas or any mixture thereof. In one embodiment of the invention, the pigment is selected from aluminium silicates, magnesium silicates and/or aluminium magnesium silicates. In one em- bodiment of the invention, the pigment is selected from aluminium silicates, calcium silicates and/or aluminium calcium silicates. In one embodiment of the invention, the first coating of the coating composition comprises at least one precipitated pigment, which is selected from aluminium sili cates, aluminium magnesium silicates, aluminium calcium silicates, aluminium cal- cium magnesium silicates, calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium cal- cium magnesium zinc silicates, aluminium magnesium zinc silicates, calcium mag- nesium zinc silicates and silicas. In one embodiment, the precipitated pigment is selected from aluminium magnesium silicates, aluminium calcium silicates, alumin- ium calcium magnesium silicates and calcium magnesium silicates. In one embodi- ment, the precipitated pigment is selected from zinc silicates, aluminium zinc sili- cates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magnesium zinc silicates. In one embodiment, the precipitated pigment is selected from silicas. In one embodiment of the invention, the porous precipitated pigments do not essentially contain titanium dioxide. In one embodiment of the invention, the precipitated, porous pigments do not contain tita- nium dioxide, i.e., the precipitated porous pigments are Ti0 ₂ -free.

In one embodiment of the invention, the first coating of the coating composition comprises at least one porous pigment, which is selected from composite pigments, which comprise titanium, which is selected from aluminium silicates, aluminium magnesium silicates, aluminium calcium silicates, aluminium calcium magnesium silicates, calcium magnesium silicates, calcium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium cal- cium magnesium zinc silicates, aluminium magnesium zinc silicates, calcium mag- nesium zinc silicates and silicas. In one embodiment, the composite pigment corn- prises titanium dioxide and at least one precipitated pigment, which is selected from aluminium magnesium silicates, aluminium calcium silicates, aluminium calcium magnesium silicates and calcium magnesium silicates. In one embodiment, the composite pigment comprises titanium dioxide and at least one precipitated pig ment, which is selected from zinc silicates, aluminium zinc silicates, calcium zinc silicates, aluminium calcium zinc silicates, aluminium calcium magnesium zinc sili cates, aluminium magnesium zinc silicates. In one embodiment, the composite pig ment comprises titanium dioxide and at least one precipitated pigment, which is se- lected from silicas.

In one embodiment of the invention, the composite pigment contains at least one of the precipitated pigments disclosed above and at most 50% by weight of titanium dioxide based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 50% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 30% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 15% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 10% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 5% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains tita- nium dioxide about 5-50% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium diox- ide about 10-50% by weight based on the weight of the composite pigment. In one embodiment of the invention, the composite pigment contains titanium dioxide about 15-50% by weight based on the weight of the composite pigment. In one embodi- ment of the invention, the composite pigment contains titanium dioxide about 15- 30% by weight based on the weight of the composite pigment.

In one embodiment of the invention, the pigment or the composite pigment does not contain polymers as additives. In one embodiment of the invention, the pigment or the composite pigment does not contain any shell structures.

In one embodiment of the invention, the precipited porous pigments and/or composite pigments may optionally contain also Na-, K-, L-, S0 ₄ -, SO3-, R0 ₄ -, BO3- , B-, PO3-, NO2-, NO3-, F-, carbonic acid-, carboxylic acid-, zinc-, manganese-, iron- , zirkonium-, nickel-, cobolt-, chrome-, barium-, sulphur-, strontium-, carbon-, Cl- residues and/or residues of other elements.

In one embodiment of the invention, the precipited porous pigments and/or composite pigments may optionally contain also stabilizing agents, dispersing agents, surfactants and/or other conventional additives.

In one embodiment of the invention, the porous pigment refers to a pigment, which has a BET-value higher than 15 m ² /g. In one embodiment of the invention, the porous pigment has a BET-value higher than 50 m ² /g.

The particles of the porous pigment and/or composite pigment of the invention are aggregates, which have a cluster-type formation made up of primary/ultimate particles. Aggregates have a definite pattern of molecules formed of primary (ele- mental) particles by an irreversible process and they cannot be broken by mechan- ical forces. As a result of the process, the specific surface area of an aggregate is smaller than the sum of its primary particles. Agglomerates consist of primary parti cles and/or aggregates which are joined loosely together e.g. at the corners or edges and can be broken by mechanical forces. Thus agglomerates can change their size and shape.

The average particle size of the porous pigment and/or composite pigment of the invention is at most 10 pm (0-10 pm), determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is below 10 pm, determined by laser measurement. In one em- bodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-10 pm or in the range of 0.2-10 pm, de- termined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 1 - 10 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention is at most 5 pm (0-5 pm), deter- mined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention is below 5 pm, deter- mined by laser measurement. In one embodiment of the invention, the average par- ticle size of the porous pigment and/or composite pigment is in the range of 0.1-5 pm or in the range of 0.2-5 pm, determined by laser measurement. In one embodi- ment of the invention, the average particle size of the porous pigment and/or com- posite pigment is in the range of 1-5 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pig- ment of the invention is at most 2 pm (0-2 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or compo- site pigment of the invention is below 2 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-2 pm or in the range of 0.2-2 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 1 - 2 pm, determined by laser measurement. In one embodiment of the invention. In one embodiment, the average particle size of the porous pigment and/or composite pigment of the inven- tion is at most 1 pm (0-1 pm), determined by laser measurement. In one embodi- ment, the average particle size of the porous pigment and/or composite pigment of the invention is below 1 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment is in the range of 0.1-1 pm or in the range of 0.2-1 pm determined by laser measurement. In one embodiment of the invention, the average particle size of the pigment and/or composite pigment is 0.1-0.6 pm or 0.2-0.6 pm, determined by la- ser measurement.

In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention after precipitation and before any grinding is at most 10 pm (0-10 pm). In one embodiment, the average particle size of the porous pigment and/or composite pigment of the invention after precipitation and before any grinding is below 10 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment after the precipitation and before grinding is in the range of in the range of 0.1-10 pm, 0.2-10 pm or 1-10 pm, determined by laser measurement. In one em- bodiment, the average particle size of the porous pigment and/or composite pigment of the invention after the precipitation and before grinding is at most 5 pm (0-5 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigement and/or composite pigment of the invention after the precipita tion and before grinding is below 5 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigement and/or composite pigment after the precipitation and before grinding is in the range of in the range of 0.1 -5 pm, 0.2-5 pm or 1 -5 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or compo- site pigment after the precipitation and before grinding is at most 2 pm (0-2 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is below 2 pm, determined by laser measurement. In one embodiment of the inven- tion, the average particle size of the poeous pigment and/or composite pigment after precipitation and before grinding is in the range of 0.1-2 pm, 0.2-2 pm or 1-2 pm, determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is at most 1 pm (0-1 pm), determined by laser measurement. In one embodiment, the average particle size of the porous pigment and/or composite pigment after pre- cipitation and before grinding is below 1 pm, determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigment and/or composite pigment after precipitation and before grinding is in the range of 0.1-1 pm or 0.2-1 pm determined by laser measurement. In one embodiment of the invention, the average particle size of the porous pigement and/or composite pig- ment after precipitation and before grinding is in the range of 0.1-0.6 pm or 0.2-0.6 pm, determined by laser measurement.

In one embodiment of the invention, the average particle size and/or the parti- cle size distribution of the pigment and/or composite pigment is determined by laser diffraction technique. In one embodiment of the invention, the average particle size and/or the particle size distribution of the pigment and/or composite pigment is de- termined by laser diffraction technique using equipment, which is able to determine particle sizes in the range of 0.02 - 2000 pm. In one embodiment of the invention, the average particle size and/or the particle size distribution of the pigment and/or composite pigment is determined with Malvern 2000-analyzer. In one embodiment of the invention, the pore volume of the pigment is typically in the range of 0.20 - 0.30 cm ³ /g. In one embodiment of the invention, the pore volume of the composite pigment is typically in the range of 0.15 - 0.20 cm ³ /g.

In one embodiment of the invention, the first coating of the coating composition comprises at least one porous pigment, which is selected from composite pigments comprising titanium dioxide and modified calcium carbonate (MCC). In one embod- iment of the invention, the Ti0 ₂ -calcium carbonate composite pigment is prepared by allowing titanium dioxide T1O2, calcium hydroxide Ca(OH)2 and carbon dioxide CO2 to react with each other and treating the obtained Ti0 ₂ -precipitated calcium carbonated composition with acid, such as sulphuric acid, H2S0 ₄ , for example, wherein the surface of the precipitated calcium carbonate is corroded porous by the acid. Modified calcium carbonates (MCC) can be prepared from ground calcium car- bonate (GCC) by corroding with acids. Marble and limestone are conceivable raw materials for ground calcium carbonate (GCC). MCCs work well in mat coatings, but not due to the porosity in glossy coatings.

The first coating of the coating composition according to the invention corn- prises also a binder, which provides opacity and/or gloss, which binder is selected according to the purpose of use of the coating composition. In one embodiment of the invention, the binder of the first coating is a binder providing opacity and gloss. In one embodiment of the invention, the binder is a binder providing gloss. In one embodiment of the invention, the binder of the first coating is a binder providing opacity. It is integral to the binder providing opacity that it increases the coverage of the coating. For example, hollow air containing structures represent a technique, which generates coverage in binders. The coating composition of the invention is suited to be used as a substitute for fillers of paper, carton, plastic, rubber and laminate, and in coatings for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. Different types of binders providing opacity and/or gloss are available commercially and a person skilled in the art selects the binder providing opacity and/or gloss according to the purpose of use of the coating composition. In one embodiment of the invention, the binder is suited to be used in substitutes for fillers of paper, carton, plastic, rubber and laminate. In one embodiment of the in- vention, the binder is suited to be used in coatings of paper, carton, plastic, rubber, laminate, concrete and wood. In one embodiment of the invention, the binder is suited to be used in paints, especially in multi layer paints. Suitable binders generally used in paints, for example, are different acryl-, alkyd-, latex-, and epoxypolymer based compounds or polyvinylalcohol- and polyurethane based compounds, among others. Other suitable binders are synthetic or natural polymers, which are based on vinylacetate, vinylethylene (VAE), polyurethane, polyester, melamine resins, silanes, siloxanes or olis, among others. Examples of binders, used among others in paints, are ROPAQUE™ Ultra E-polymer (The Dow Chemical Company) which provides coverage (opacity) and shade (brightness), but does not provide gloss, and Acronal ^® S 728-polymer (BASF Corporation), which provides gloss.

The first coating of the coating composition of the invention comprises 0-30% binder based on the weight of the pigment-binder composition or the composite pig ment-binder composition. In one embodiment of the invention, the first coating corn- prises 1 -30% binder based on the weight of the pigment-binder composition or the composite pigment-binder composition. In one embodiment of the invention, the first coating comprises 1 -20% binder based on the weight of the pigment-binder compo- sition or the composite pigment-binder composition. In one embodiment of the in- vention, the first coating comprises 1 -10% binder based on the weight of the pig- ment-binder composition or the composite pigment-binder composition. In one em- bodiment of the invention, the first coating comprises 3-10% binder based on the weight of the pigment-binder composition or the composite pigment-binder compo- sition. In one embodiment of the invention, the first coating comprises 4-6% binder based on the weight of the pigment-binder composition or the composite pigment- binder composition. In one embodiment of the invention, the first coating comprises 5% binder based on the weight of the pigment-binder composition or the composite pigment-binder composition. In one embodiment of the invention, the pigment:binder-ratio and/or the com- posite pigment:binder-ratio of the first coating is in the range of 70-100:30-0. In one embodiment of the invention, the pigment:binder-ratio and/or the composite pig- ment:binder-ratio of the first coating is in the range of 70-99:30-1 . In one embodi- ment of the invention, the pigment:binder-ratio and/or the composite pig- ment:binder-ratio of the first coating is in the range of 80-99:20-1 . In one embodi- ment of the invention, the pigment:binder-ratio and/or the composite pig- ment:binder-ratio of the first coating is in the range of 90-99:10-1 . In one embodi- ment of the invention, the pigment:binder-ratio and/or the composite pig- ment:binder-ratio is in the range of 90-97:10-3. In one embodiment of the invention, the pigment:binder-ratio and/or the composite pigment:binder-ratio of the first coat- ing is in the range of 94-96:6-4. In one embodiment of the invention, the pig- ment:binder-ratio and/or the composite pigment:binder-ratio is 95:5.

The second coating of the coating composition according to the invention corn- prises a binder providing opacity and/or gloss. In one embodiment of the invention, the binder of the second coating is a binder providing opacity and gloss. In one embodiment of the invention, the binder of the second coating is a binder providing opacity. In one embodiment of the invention, the binder of the second coating is a binder providing gloss. The binder is selected based on the purpose of use of the coating composition. The coating composition of the invention is suitable for use as a substitute for fillers of paper, carton, plastic, rubber and laminate, and in coatings for paper, carton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. Different types of binders are available commercially and a person skilled in the art selects the binder according to the purpose of use of the coating composition. In one embodiment of the invention, the binder is suited to be used in substitutes for fillers of paper, carton, plastic, rubber and laminate. In one embodiment of the invention, the binder is suited to be used in coatings of paper, carton, plastic, rubber, laminate, concrete and wood. In one embodiment of the in- vention, the binder is suited to be used in paints, especially in multi layer paints. Suitable binders generally used in paints, for example, are different acryl-, alkyd-, latex-, and epoxypolymer based compounds or polyvinylalcohol- and polyurethane based compounds, among others. Other suitable binders are synthetic or natural polymers, which are based on vinylacetate, vinylethylene (VAE), polyurethane, pol- yester, melamine resins, silanes, siloxanes or olis, among others. Examples of bind- ers, used among others in paints, are ROPAQUE™ Ultra E-polymer (The Dow Chemical Company) which provides coverage (opacity) and shade (brightness), but does not provide gloss, and Acronal ^® S 728-polymer (BASF Corporation), which provides gloss.

The coating composition of the invention comprises optionally a third coating, which comprises a binder providing gloss. The binder is selected based on the pur- pose of use of the coating composition.

The coating composition of the invention is suitable for use as a substitute for fillers of paper, carton, plastic, rubber and laminate, and in coatings for paper, car- ton, plastic, rubber, laminate, concrete and wood as well as in paints, especially in multi layer paints. Different types of binders are available commercially and a person skilled in the art selects the binder according to the purpose of use of the coating composition. In one embodiment of the invention, the binder is suitable to be used in substitutes for fillers of paper, carton, plastic, rubber and laminate. In one embod- iment of the invention, the binder is suited to be used in coatings of paper, carton, plastic, rubber, laminate, concrete and wood. In one embodiment of the invention, the binder is suited to be used in paints, especially in multi layer paints. Suitable binders generally used in paints, for example, are different acryl-, alkyd-, latex-, and epoxypolymer based compounds or polyvinylalcohol- and polyurethane based corn- pounds, among others. Other suitable binders are synthetic or natural polymers, which are based on vinylacetate, vinylethylene (VAE), polyurethane, polyester, mel- amine resins, silanes, siloxanes or olis, among others. Example of a binder, used among others in paints, providing gloss is Acronal ^® S 728-polymer (BASF Corpora- tion).

In one embodiment of the invention, the binder of the first coating of the coating composition is a binder providing opacity and the binder of the second coating is a binder provding gloss. In one embodiment of the invention, the binder of the first coating of the coating composition is a binder providing opacity and the binder of the second coating is a binder provding opacity. In one embodiment of the invention, the binder of the first coating is a binder providing opacity, and the binder of the second coating is a binder provding opacity and the binder of the third coating is a binder providing gloss. In one embodiment of the invention, the binder of the first coating is a binder providing opacity, and the binder of the second coating is a binder provding gloss and the binder of the third coating is a binder providing gloss.

In one embodiment of the invention, the binders of the first, the second and optionally the third coating are suitable for use in substitutes for fillers of paper, car- ton, plastic, rubber and laminate. In one embodiment of the invention, the binders of the first, the second and optionally the third coating are suitable for use in coatings of paper, carton, plastic, rubber, laminate, concrete and wood. In one embodiment of the invention, the binders of the first, the second and optionally the third coating are suitable for use in paints, especially in multi layer paints.

The coating composition of the invention is suitable for use as substitutes for fillers of paper, carton, plastic and rubber. The coating composition of the invention is suitable for use in coatings of paper, carton, plastic, rubber, laminate, concrete and wood, and in paints, especially in multi layer paints. The coating composition of the invention is suitable for use as a coating providing opacity and brightness. The coating composition of the invention is suitable for use as a substitute for titanium dioxide without impairment of the optical properties of the produced product.

The following facts affect the optical efficiency or the light scattering in a ma- terial when light attempts to traverse the material in coated or uncoated materials:

- air-solid -interfaces (the refractive index of the air is about 1 and usually the other refractive indexes, such as plastics, fibers, rubbers and most pigments and fillers, are 1 .4 -1 .8),

- the distance between the pigments,

- the empty air pores of the pigments

- the refractive indexes of substances,

- the small average particle size of the pigments - optimum half of the wave- lenght of the light (visible light is in the range of 400-780 nm),

- the particle size distributions of the pigments and the binders.

Critical Pigment Volume Concentration (CPVC) is, especially in coatings, an important measure describing the ratio of the binder and the pigment in the coating, wherein the pigments are totally coated with the binder and the pores of the pigment are filled with the binder. With values smaller that CPVC, the portion of the binder is higher than that of pigments in the coating, and the other way around, when the value is higher than CPVC. Typically the properties of the coating layer, when CPVP is exceded, develop so that porousity increases, corrosion resistance increases, density increases, gloss decreases and abrasion resistance (wet) decreases.

In coatings of papers and in primers, there is usually considerably more pig ment than binder. In gloss paints, on the other hand, there is considerably more binder than pigment. Gloss of paints can be increased by using non-porous pig- merits having low BET-value, binders providing gloss and using oil -base paint in- stead of aqueous paint. The gloss of papers and cartons can be increased by cal- endaring and by using laminar pigments, especially kaolines.

PVC of gloss and semi-gloss paints, whose optical porperties are achieved by preventing the agglomeration of Ti0 ₂ -particles preferably with extenders having size of about 0.2-0.5 pm, is about 20-40%. PVC of less glossy indoor and outdoor paints is typically 40-65%. Matt indoor paints, whose opacity and brightness are increased by air pores in the coating structure, have PVC about 65-95%.

It was suprisingly found that titanium dioxide can be replaced partly (about 1 % by weight, 1 -5% by weight, 5-15% by weight, 10-25% by weight, at least 25% by weight, 25-50% by weight, 50-75% by weight) or totally (100% by weight) with the coating and the coating composition of the invention as a pigment providing optical properties (opacity and brightness) without imparing the optical properties, and achieve gloss values, which are not obtained with the known coating applications of porous pigments.

Preferably this is achieved with the coating of the invention, more preferably with the coating composition of the invention, which comprises a first coating, which comprises at least one porous pigment and a binder providing opacity and/or gloss and a second coating, which comprises a binder providing opacity and/or gloss, and most preferably with the coating composition, which comprises a first coating, which comprises at least one porous pigment and a binder providing opacity and/or gloss and a second coating, which comprises a binder providing opacity and/or gloss and a third coating, which comprises a binder providing gloss. In this triple coating, the pigment with a small amount of binder forms the first coating. The second coating formed from a binder providing opacity fulfills the empty spaces between the pig- ments of the first coating and partly the pores of the pigments. The third coating formed from a binder providing gloss is used to make the coating composition glossy .The pores of the pigment are full with air after the coating and drying, wherein when coating a binder providing opacity (no pigment) a coating structure, where pigments provide optical properties and the opacity providing binder between the pigments provides synergetic efficiency, is achieved. This strengthens the total ef- fect more than the pigment coating or the opacity providing binder alone. This suits especially coating applications, which require little gloss.

It was suprisingly found, that the coating composition of the invention, which comprises a first coating comprising at least one porous pigment and a binder providing opacity and/or gloss and a second coating comprising a binder providing opacity, functions as a matte coating, which generates excellent coverage and brightness. In this coating composition, the binder of the first coating is preferably an opacity providing binder. The binder of the second coating of this coating corn- position is preferably essentially pigment free.

The coating and/or coating composition of the invention is suited to be used as a substitute for fillers of paper, carton, plastic, rubber and laminate. In addition to the pigment, this kind of filler compositions contain also conventional manufacturing agents and additives of filler compositions. Additionally, the coating and/or coating composition of the invention is suited to be used as a coating in papers, cartons, plastics, rubbers, laminates, concretes and wood. In addition to the pigment, coat- ings of this kind contain also conventional manufacturing agents and additives of coating compositions. Futher, the coating and/or the coating composition of the in- vention is suited to be used in paints. In addition to the pigment, paints of this kind contain also conventional manufacturing agents and additives of paints. Other pig ments, rheological modifiers, adhesives and other necessary additives depending on the application can be used with the coating and/or coating composition of the invention.

In one embodiment of the invention, the coating and/or coating composition is suitable for use as a pigment coating and/or coating providing opacity and/or bright- ness. In one embodiment of the invention, the coating and/or coating composition is suited to be used to replace titanium dioxide without imparing the optical charac- teristics. The coating and/or coating composition of the invention is suited to be used as a substitute for titanium dioxide in fillers of paper, carton, plastic, rubber and laminate. In addition, the coating and/or coating composition of the invention is suited to be used as a substitute for titanium dioxide in coatings, which are used in papers, cartons, plastics, rubbers, concretes, laminates and wood, and as a pigment in paints.

About 1 -100% by weight of titanium dioxide can be replaced with the coating and/or coating composition of the invention without any detectable impairment in the optical characteristics of the produced material.

In one embodiment of the invention, 5 -100% by weight, 10-100% by weight, 15-100% by weight of titanium dioxide can be replaced with the coating and/or coat- ing composition of the invention without any detectable impairment in the optical characteristics. In one embodiment of the invention, 25 -100% by weight of titanium dioxide can be replaced with the coating and/or coating composition of the invention without any detectable impairment in the optical characteristics. In one embodiment of the invention, 50 -100% by weight of titanium dioxide can be replaced with the coating and/or coating composition composition of the invention without any detect- able impairment in the optical characteristics. In one embodiment of the invention, 75-100% by weight of titanium dioxide can be replaced with the coating and/or coat- ing composition of the invention without any detectable impairment in the optical characteristics. In one embodiment of the invention, about 25% by weight, about 50% by weight, about 75% by weight, about 100% by weight of titanium dioxide can be replaced with the coating and/or coating composition of the invention without any detectable impairment in the optical characteristics. In one embodiment of the in- vention, about 100% by weight of titanium dioxide can be replaced with the coating and/or coating composition of the invention without any detectable impairment in the optical characteristics.

Since titanium dioxide can be replaced partially or totally with the coating or the coating composition of the invention, remarkable savings in raw material costs can be achieved. With the coating or the coating composition of the invention the equivalent light-scattering ability is achieved more advantageously than with tita- nium dioxide. With the coating or the coating composition of the invention the mate- rials to be produced can be thinned and/or lightened without weakening the attain- able light-scattering ability (brightness and opacity) compared to the use of titanium dioxide. Thus, lowering the basis weight of paper or carton is enabled, the number of coating layers can be reduced, coating layers from multilayer structures can be removed as unnecessary, or the coating layers, paint or laminate can be thinned without weakening the spreading capacity and/or brightness and opacity. Each of these actions leads to the reduction of material costs, increace in productivity and environmental sustainability.

The present invention relates also to a method for producing a coating corn- position comprising a first coating, which comprises at least one porous pigment and a binder, and a second coating, which comprises a binder providing opacity and/or brightness, and optionally a third coating, which comprises a binder providing gloss, which method comprises the following steps: a) bringing a pigment and a binder or a composite pigment and a binder into contact with each other in order to achieve the first coating, b) optionally drying the first coating c) adding the second coating, which comprises a binder providing opacity and/or gloss, d) optionally drying the coating composition, e) optionally adding the third coating, which comprises a binder providing gloss f) optionally drying the obtained coating composition.

In one embodiment of the invention, the method comprises the following steps: a) bringing a pigment and a binder or a composite pigment and a binder into contact with each other in order to achieve the first coating, b) drying the first coating, c) adding the second coating, which comprises a binder providing opacity and/or gloss, d) drying the coating composition, e) adding the third coating, which comprises a binder providing gloss, f) drying the obtained coating composition.

In one embodiment, the invention relates to a method for producing a coating composition comprising a first coating, which comprises at least one porous pigment and a binder, and a second coating, which comprises a binder providing opacity and/or brightness, and optionally a third coating, which comprises a binder providing gloss, which method comprises the following steps: a) bringing a pigment and a binder or a composite pigment and a binder into contact with each other in order to achieve the first coating, b) optionally drying the first coating, c) adding the second coating, which comprises a binder providing opacity and/or gloss, d) optionally drying the coating composition e) optionally adding the third coating, which comprises a binder providing gloss, f) optionally drying the obtained coating composition.

In one embodiment of the invention, the method comprises the following steps: a) bringing a pigment and a binder or a composite pigment and a binder into contact with each other in order to achieve the first coating, b) drying the first coating, c) adding the second coating, which comprises a binder providing opacity and/or gloss, d) drying the coating composition, e) adding the third coating, which comprises a binder providing gloss, f) drying the obtained coating composition wherein the at least one prepitated porous pigment is selected from: a) precipitated aluminium silicates, aluminium magnesium silicates, aluminium calcium silicates, aluminium calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium silicates, aluminium cal- cium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magne- sium zinc silicates, magnesium zinc silicates, calcium magnesium zinc silicates, sil icas or any mixture thereof, wherein the precipitated pigment does not contain tita- nium dioxide, b) precipitated composite pigments, which comprise titanium dioxide and alu- minium silicates, calcium silicates, aluminium magnesium silicates, aluminium cal- cium silicates, aluminium calcium magnesium silicates, zinc silicates, aluminium zinc silicates, calcium zinc silicates, calcium magnesium silicates, aluminium cal- cium zinc silicates, aluminium calcium magnesium zinc silicates, aluminium magne- sium zinc silicates, magnesium zinc silicates, calcium magnesium zinc silicates, sil icas or any mixture thereof, or c) composite pigments, which comprise titanium dioxide and modified calcium carbonate (MCC). The drying steps of the method can be performed with any suitable method known and/or used by a person skilled in the art.

The method is suitable for producing the coating compositions disclosed in detail above.

The following examples are given to illustrate the invention without, however, restricting the invention thereto.

Examples

Materials

The binder used in the below examples are ROPAQUE™ Ultra E latex polymer (The Dow Chemical Company) and Acronal ^® S 728 latex polymer (BASF Corpora- tion).

ROPAQUE™ Ultra E latex polymer (Dow) provides coverage (opacity) and shade (brightness), but does not provide gloss. ROPAQUE™ Ultra E -polymer is an emusion polymer, which is spherical and hollow inside. The core is full of the solvent of the coating until the solvent evaporates after drying and the hollow core is filled with air or it is full of air already before drying. The average particle size is about 0.4 pm. ROPAQUE™ Ultra E does not form a uniform film after the drying unlike most latexes. Typically, it is used as an extender to prevent the agglomeration of Ti0 ₂ -particles.

Acronal ^® S 728 latex (BASF) provides gloss, but does not provide opacity and shade. Acronal ^® S 728-polymer is an aqueous dispersion of styrene-acrylate copol- ymer, which is used as a binder.

In examples 1 -3, ROPAQUE™ Ultra E latex is referred as“Dow” and Acronal ^® S 728 latex is referred as“Basf .

In examples 1 -3, sodium aluminium magnesium silicate-pigment (KEU1 ), which is prepared according to the method disclosed in the Finnish patent applica- tion 20176090, is used as the pigment. The particle size of the pigment was 1 .91 pm. In examples 1 -3, sodium aluminium magnesium titanium dioxide silicate-pig ment (KEU2), which is prepared according to the method disclosed in the Finnish patent application 20176092, is used as the composite pigment. The particle size of the composite pigment was 0.77 pm. The coating pastes disclosed in Table 1 contain 5% latex (Dow or Basf) in water. The pH of this aqueous slurry was kep above the pH-value 8.3 with the addi- tions of lye and by adding a thickener (Sterocoll FS, BASF) the viscosity of the dis persion was adjusted to 800 - 850 cp (Brookfield, 100 rpm, Spindle 4). As can be seen from the results, Dow-latex provides opacity and shade (bright- ness), but does not provide gloss. Basf-latex provides gloss, but does not provide opacity and shade (brightness).

Table 1.

Example 1

In the example, coatings according to the invention containing pigments KEU1 and KEU2 were compared with rutile-titanium dioxide (SR5 slurry, Venator) Ti02, control, test point. Later, this is marked as Ti02, control test point. The above-dis- closed KEU1 - and KEU2- pigment dispersions were used in manufacturing of coat- ing paste, which contained 5% dry pigment in water and 5% latex (Dow) based on the amount of dry pigment. The pH of this aquoeus slurry was kept above pH-value 8.3 with the additions of lye and a thickener (Sterocoll FS, BASF) was added until the viscosity of the dispersion of 800 - 850 cp (Brookfield, 100 rpm, Spindle 4) was achieved. The opacity and tone of the coating of 5 g/m ² were measured with the opaci- meter (Rhopoint Novoshade Duo+) and the gloss with gloss meter (Rhodopoint No- vogloss Trio). The coating was spread with standard rod (K Bar) of the rod coating method (RK101 Control Coater) onto a plastic film (Leneta 1 mm, clear polyester sheets). The coatings were dried in air at 60°C. Table 2.

Both KEU-pigments provide better values for coverage (opacity) and bright ness (shade) than T1O2.

Example 2 In the example, it is shown that by coating with the coating composition of the present invention synergistic advantages are achieved between the first coatings of the invention containing KEU1 and KEU2 pigments and the Dow-binder used as the second coating, which lifts the opacity and shade to a totally new level, especially when KEU2-pigment is used. No gloss is yet achieved due to the used Dow-latex, which does not provide gloss but provides opacity and shade.

The first coating is done with the KEU-pigments with the corresponding coating pastes as in example 1. The second coating is done as in example 1 , but with pure Dow-latex without a pigment, which was prepared as dislosed in paragraph Materi- als. It is advantageous when using the coating compostion according to the inven- tion that the pores of the KEU-pigments are rendered empty from water by drying, wherein the Dow-latex fills the pores between the pigments and partly in the struc- tures of the pigments after the second coating and drying.

In Ti02, control test point, the coating paste is prepared as in example 1. The plastic film is first coated with this coating paste in an amount of 5 g/m ² and dried. After this, also a 2 g/m ² coating is applied and dried in order to have an equal amount of dry coating in all test points of Table 3. Table 3.

Example 3 The results of Table 4 show, that when coating once with a Ti0 ₂ -coating paste, which based on its dry weight is half pigment and half latex (Basf), a satisfactory level of opacity, shade and gloss is achieved. The opacity and shade values of the pigments KEU1 and KEU2 decrease from the values given in the previous exam- pies, correspondingly. This is because the pores of the porous KEU-pigments are filled with Basf-latex, which has a refractive index of about 1.4-1.5, which is thus higher than that of air. The gloss-characterstics are also worse than in T1O2, control test point. Table 4.

The results of Table 5 show values received with the coating composition of the invention when the coating compositions are prepared as disclosed in Example 1. 5 g/m ² coating for the first time with a paste, which contains 95% pigment and 5%

Dow-latex based on the weight of the pigments, and drying. For the second coating time, 5 g/m ² coating with Basf-latex, which provides gloss, is applied. With KEU2- pigment, the same level in the characteristiscs is achieved than with T1O2, control test point in Table 4, however with thicker total amount of coating. Table 5.

Table 6 shows results of a coating a plastic film with the three-coating compo- sition of the invention. Drying with air 60 ^° C was performed between the coatings. The first coating and drying are as in Example 1. As a second coating, a 2 g/m ² Dow-coating without pigments (prepared as disclosed in paragraph Materials) is ap- 5 plied over this coating and dried. As a third coating, a 5 g/m ² Basf-coating (prepared as disclosed in paragraph Materials) is applied over this coating and dried. Thus, the values of opacity, shade and gloss achieved with both KEU-pigments are in the same level than in T1O2, control test point.

Table 6.

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