Patent Description:
Polysiloxane-polyester copolymers are frequently used for cookware coatings or for electrical domestic appliance such as coatings for steam irons. The polysiloxane-polyester copolymers are able to form release or non-stick coatings to which extraneous materials will not adhere and residues for example food residues or spray starch can be removed easily as the cookware or appliance is cleaned. Cookware coatings include the external and interior surfaces of the utensils, such as sauté or frying pans, toasters, deep-fat fryers and baking trays.

These coatings require, along with thermal stability, resistance to scratches and marring, particularly when heated. Most organic coatings will exhibit some degree of thermo-plasticity that, under normal kitchen conditions, can result in damaged coatings. The polyester part imparts low thermoplasticity, high flexibility and good pigmentability while the polysiloxane part brings heat resistance, weathering resistance and low surface tension.

For example, <CIT> discloses a silicone-polyester copolymer prepared by reacting a silicone with a polyester, wherein the silicone comprises: <NUM> to <NUM> mole% of a siloxane unit represented by the formula: SiO<NUM>/<NUM> (hereafter referred to as "Q"), <NUM> to <NUM> mole% of a siloxane unit represented by the formula: RSiO<NUM>/<NUM> (hereafter referred to as "T"), <NUM> to <NUM> mole% of a siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM> (hereafter referred to as "D"), and <NUM> to <NUM> mole% of a siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM> (hereafter referred to as "M"), wherein each R is independently a monovalent hydrocarbon group with C<NUM>-<NUM> carbon atoms and each siloxane unit are random in the silicone; and <CIT> discloses a silicone-polyester copolymer, wherein the silicone parts contains comprises: a siloxane unit represented by the formula: C<NUM>H<NUM>SiO<NUM>/<NUM> (hereafter referred to as "TPh"), a siloxane unit represented by the formula: CH<NUM>SiO<NUM>/<NUM> (hereafter referred to as "TMe") and Q unit and free of D unit.

These patents mention that these polysiloxane-polyester copolymers are able to form heat resistance and non-stick coating. However, these patents do not mention about the durability of heat resistance and non-stick, or anti-graffiti properties of coating.

Other patent publications useful in understanding the present invention are <CIT> and <CIT>. <CIT> provides a polysiloxane-containing copolymer obtained by copolymerization of a silicone compound having a basic backbone shown by the general formula (I):.

(R<NUM> <NUM>SiO<NUM>)a(R<NUM> <NUM>SiO)b(R<NUM>SiO<NUM>)c(SiO<NUM>)d     (I).

wherein, R<NUM>, R<NUM> and R<NUM> are each an aromatic residue or hydrocarbon group having a carbon atom number of <NUM> to <NUM>, which may be the same or different; and "a", "b", "c" and "d" satisfy a relationship (a+b+c+d)=<NUM>, and said aromatic residue accounts for <NUM> to <NUM>% of the total functional groups of the silicone compound, and a relationship <NUM><c+d holds in the general formula (I). <CIT> discloses a silicone-polyester composition and a process of forming a silicone-polyester composition. The silicone part of the silicone-polyester composition contains Tph and Q units and is free of D units. A polyester precursor and a silicone precursor are mixed and reacted together so as to form a silicone-polyester composition wherein the silicone part contains Tph, Q units and optionally TMe units.

This invention differs to these patents mentioned above is to incorporate siloxane resin-linear block in the copolymer with chemical bonding to provide the durable thermal resistance, hardness, also improve non-stick and anti-graffiti properties.

An object of the present invention is to provide a novel polysiloxane-polyester block copolymer comprising a siloxane resin block, a siloxane linear block, and a polyester block which can be used for a protective coating on a substrate to provide durable heat-resistance, hot hardness, release and anti-graffiti properties. Another object of the present invention is to provide a method for producing the polysiloxane-polyester block copolymer.

The polysiloxane-polyester block copolymer of the present invention comprises:.

The siloxane resin block (i) preferably comprises <NUM> to <NUM> mole% of the siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM>, and <NUM> to <NUM> mole% of the siloxane unit represented by the formula: SiO<NUM>/<NUM>, based on the molar sum of these siloxane units.

The siloxane resin block (i) preferably comprises: TPh unit, TMe unit, and Q unit.

The siloxane resin block (i) preferably comprises: <NUM> to <NUM> mole% of TPh unit, <NUM> to <NUM> mole% of TMe unit, and <NUM> to <NUM> mole% of Q unit, based on the molar sum of these siloxane units.

The siloxane linear block (ii) is preferably represented by the formula: ((CH<NUM>)<NUM>SiO<NUM>/<NUM>)n, wherein "n" is a positive number of at least <NUM>.

The content of the siloxane resin block (i) and the siloxane linear block (ii) is <NUM> to <NUM> % by mass based on the sum of the blocks (i) through (iii).

The method for producing a polysiloxane-polyester block copolymer of the present invention, comprises the following steps:.

The silane compound represented by the formula: R<NUM>SiX<NUM>, is preferably phenyltrialkoxysilane and methyltrialkoxysilane, and the siloxane unit represented by the formula: SiX<NUM> is preferably tetraalkoxysilane.

The polyester is preferably neopentylglycol or trimethylolpropane.

The use of the polysiloxane-polyester block copolymer of the present invention is characterized by forming a coating on a substrate.

The substrate is preferably made of aluminum, stainless steel, iron, plastics or glass.

The polysiloxane-polyester block copolymer of the present invention can cure to form a protective coating on a substrate which is made of aluminum, stainless steel, iron, plastics or glass to provide durable heat-resistance, hot hardness, release and anti-graffiti properties.

The polysiloxane-polyester block copolymer of the present invention comprises the siloxane resin block (i), the siloxane linear block (ii) and the polyester block (iii).

The siloxane resin block (i) comprises : a siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM>, and comprises optionally Q unit.

In the formula, R<NUM> is a monovalent hydrocarbon group such as an alkyl group with C<NUM>-<NUM> carbon atoms, alkenyl group with C<NUM>-<NUM> carbon atoms, aryl group with C<NUM>-<NUM> carbon atoms, and an aralkyl group with C<NUM>-<NUM> carbon atoms. Specific examples thereof include alkyl groups, such as a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and a dodecyl group; alkenyl groups, such as a vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, and a dodecenyl group; aryl groups, such as a phenyl group, tolyl group, xylyl group, and a naphthyl group; aralkyl groups, such as a benzyl group, and a phenethyl group; and groups in which some or all of the hydrogen atoms bonded in these groups are substituted with halogen atoms, such as a chlorine atom and bromine atom. Of these, the methyl group and phenyl group are preferable. That is, the siloxane resin block (i) preferably comprises: TPh unit, TMe unit, and Q unit.

In the siloxane resin block (i), the content of the siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM> is not limited, but the siloxane resin block (i) preferably comprises: <NUM> to <NUM> mole% of the siloxane unit represented by the formula: R<NUM>SiO<NUM>/<NUM>, and <NUM> to <NUM> mole% of Q unit, based on the molar sum of these siloxane units, more preferably <NUM> to <NUM> mole% of TPh unit, <NUM> to <NUM> mole% of TMe unit, and <NUM> to <NUM> mole% of Q unit, based on the molar sum of these siloxane units. This is because the content of TPh unit is greater than or equal to the lower limit of the aforementioned range, thermal resistance and gloss of the coating is good, when the content TMe unit is greater than or equal to the lower limit of the aforementioned range, the composition has good for film forming, and when the content Q unit is greater than or equal to the lower limit of the aforementioned range, the coating become hard.

The siloxane linear block (ii) is represented by the formula: (R<NUM><NUM>SiO<NUM>/<NUM>)n.

In the formula, each R<NUM> is independently a monovalent hydrocarbon group such as said alkyl group with C<NUM>-<NUM> carbon atoms, alkenyl group with C<NUM>-<NUM> carbon atoms, aryl group with C<NUM>-<NUM> carbon atoms, and aralkyl group with C<NUM>-<NUM> carbon atoms. Of these, the alkyl group, especially, the methyl group is preferable. That is, the siloxane linear block (ii) is preferably represented by the formula: ((CH<NUM>)<NUM>SiO<NUM>/<NUM>)n.

In the formula, "n" is a positive number of at least <NUM>, preferably a positive number of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, alternately, <NUM> to <NUM>.

The polyester block (iii) is not limited, but suitable polyesters are formed in conventional manner from carboxylic acids (or their anhydrides) having acid functionalities of <NUM> or greater and polyols having hydroxyl functionalities of <NUM> or greater.

Examples of suitable multi-functional carboxylic acids include benzene-<NUM>,<NUM>,<NUM>-tricarboxylic acid, phthalic acid, tetrahydraphthalic acid, hexahydrophthalic acid, endobicyclo-<NUM>,<NUM>,<NUM>-<NUM>-heptyne-<NUM>,<NUM>-dicarboxylic acid, tetrachlorophthalic acid, cyclohexanedioic acid, succinic acid, isophthalic acid, terephthalic acid, azelaic acid, maleic acid, trimesic acid, <NUM>,<NUM>-dichlorophthalic acid, tetrachlorophthalic acid, adipic acid, sebacic acid, and like carboxylic acids.

Examples of suitable multi-functional alcohols include glycerin, trimethylolpropane, trimethylolethane, trishydroxyethylisocyanurate, pentaerythritol, ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, <NUM>,<NUM>-, <NUM>,<NUM>- and <NUM>,<NUM>-butanediols, heptanediol, hexanediol, octanediol, <NUM>,<NUM>'-bis (<NUM>-cyclohexanol)propane, neopentyl glycol, <NUM>,<NUM>,<NUM>-trimethylpentane-<NUM>,<NUM>-diol, <NUM>,<NUM>-dimethylolcyclohexane, <NUM>,<NUM>,<NUM>-trimethylpentane diol, etc..

Whether the polyester is substantially carboxylic acid functional having COOH groups, or hydroxyl functional having OH groups, depends upon the COOH/OH molar ratio of the monomer mix. Most hydroxyl functional polyesters useful in the invention have hydroxy equivalent weights between <NUM> and <NUM>,<NUM>. Most carboxylic acid functional polyesters useful in the invention have acid numbers of between <NUM> and <NUM> KOH/g. Most polyesters useful in the invention may be substantially straight chain having either hydroxyl or carboxylic acid functional of <NUM> or more or may be branched having hydroxyl or carboxylic acid functionality more than <NUM>. In some cases, mixtures of polyesters having different functionalities may be used.

In certain embodiments, the polyester is prepared by reacting isophthalic acid with trimethylol propane. Alternatively, other acids, such as isophthalic acid, TPA, trimelitic anhydride, and tetrahydraphthalic acid, and other alcohols, such as TME, MPG, TMP, and NPG can be used.

The polysiloxane-polyester block copolymer is a new material synthesized by incorporating Q units along with TPh unit into a silicone intermediate that was subsequently reacted with a hydroxyl functional polyester without gelation or prohibitive viscosity build. The polysiloxane-polyester block copolymer exhibits the needed boost in hot hardness. Therefore, the invention provides a silicone-polyester composition characterised in that the silicone part contains silicone resin block and silicone linear block.

The content of the siloxane resin block (i) and the siloxane linear block (ii) in the polysiloxane-polyester block copolymer is not limited, but it is preferably <NUM> to <NUM> % by mass, or <NUM> to <NUM> % by mass based on the sum of the blocks (i) through (iii). This is because when the content is greater than or equal to the lower limit of the aforementioned range, anti-graffiti performance is good, whereas when the content is less than or equal to the upper limit of the aforementioned range, the gelation risk due to reaction with polyester decreases.

While, the siloxane linear block (ii) in the polysiloxane-polyester block copolymer is not limited, but it is preferably <NUM> to <NUM> % by mass, or <NUM> to <NUM> % by mass based on the sum of the blocks (i) through (iii). This is because when the content is greater than or equal to the lower limit of the aforementioned range, release and anti-graffiti performance is good, whereas when the content is less than or equal to the upper limit of the aforementioned range, hardness and toughness of the coating is good.

The invention further provides a process of forming the polysiloxane-polyester block copolymer characterised in that a polyester precursor or polyester resin and a silicone precursor or silicone resin are reacted together, wherein the silicone part contains T and/or Q units and siloxane linear block. The method for producing a polysiloxane-polyester block copolymer of the present invention, comprises the following steps (<NUM>) though (<NUM>).

Step (<NUM>) is to react a siloxane represented by the formula: HO(R<NUM><NUM>SiO)nH with a silane compound represented by the formula: R<NUM>aSiX(<NUM>-a) to produce a siloxane linear block precursor.

In the formula of the siloxane, each R<NUM> is independently a monovalent hydrocarbon group such as said alkyl group with C<NUM>-<NUM> carbon atoms, alkenyl group with C<NUM>-<NUM> carbon atoms, aryl group with C<NUM>-<NUM> carbon atoms, and aralkyl group with C<NUM>-<NUM> carbon atoms. Of these, the alkyl group, especially, the methyl group is preferable. That is, the siloxane is preferably represented by the formula: HO((CH<NUM>)<NUM>SiO<NUM>/<NUM>)nH.

In the formula of the siloxane, "n" is a positive number of at least <NUM>, preferably a positive number of <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, alternately, <NUM> to <NUM>.

In the formula of the silane, each R<NUM> is independently a monovalent hydrocarbon group such as said alkyl group with C<NUM>-<NUM> carbon atoms, alkenyl group with C<NUM>-<NUM> carbon atoms, aryl group with C<NUM>-<NUM> carbon atoms, and aralkyl group with C<NUM>-<NUM> carbon atoms. Of these, the alkyl group, especially, the methyl group is preferable.

In the formula of the silane, X is a hydrolysable group such as an oximo group, acetoxy group, halogen atom, and an alkoxy group.

In the formula of the silane, "a" is a number of <NUM> to <NUM>, preferably <NUM> or <NUM>.

Examples of the silane include methyl tris(methylethylketoxime)silane (MTO), methyl triacetoxysilane, ethyl triacetoxysilane, tetraacetoxysilane, tetraoximesilane, dimethyl diacetoxysilane, dimethyl dioximesilane, and tris(methylmethylketoxime)silane.

In step (<NUM>), typically a silanol ended polydiorganosiloxane is reacted with an "endblocking" compound such as an alkyltriacetoxysilane or a dialkylketoxime. The stoichiometry of the endblocking reaction is typically adjusted such that a sufficient amount of the endblocking compound is added to react with all the silanol groups on the polydiorganosiloxane. Typically, a mole of the endblocking compound is used per mole of silanol on the polydiorganosiloxane. Alternatively, a slight molar excess such as <NUM> to <NUM>% of the endblocking compound may be used. The reaction is typically conducted under anhydrous conditions to minimize condensation reactions of the silanol polydiorganosiloxane. Typically, the silanol ended polydiorganosiloxane and the endblocking compound are dissolved in an organic solvent under anhydrous conditions, and allowed to react at room temperature, or at elevated temperatures (up to the boiling point of the solvent).

Step (<NUM>) is to co-hydrolyze and condense the said siloxane linear block precursor, a silane compound represented by the formula: R<NUM>SiX<NUM>, and optional a silane compound represented by the formula: SiX<NUM>, to produce a siloxane linear block-siloxane resin block precursor.

In the formula of the former silane, R<NUM> is a monovalent hydrocarbon group such as said alkyl group with C<NUM>-<NUM> carbon atoms, alkenyl group with C<NUM>-<NUM> carbon atoms, aryl group with C<NUM>-<NUM> carbon atoms, and aralkyl group with C<NUM>-<NUM> carbon atoms. Of these, the methyl group and phenyl group are preferable.

In the formula of the former silane, X is a hydrolysable group such as an oximo group, acetoxy group, halogen atom, and an alkoxy group.

Examples of the former silane include phenyl trimethoxysilane, phenyl triethoxysilane, methyl trimethoxysilane, and methyl triethoxysilane.

In the formula of the latter silane, X is a hydrolysable group such as an oximo group, acetoxy group, halogen atom, and an alkoxy group.

Examples of the latter silane include tetraethylorthosilicate, and tetramethylorthosilicate.

In step (<NUM>), acid may be added to co-hydrolyze and condense the said siloxane linear block. Examples of the acid include HCl.

The siloxane linear block-siloxane resin block precursor comprises the siloxane resin block and the siloxane linear block, wherein the siloxane linear block is represented by the formula: (R<NUM><NUM>SiO<NUM>/<NUM>)n, wherein R<NUM> and "n" are as defined above.

Step (<NUM>) is to condense the said siloxane linear block-siloxane resin block precursor with polyester having a reaction group. The polyester is not limited, but suitable polyesters are formed in conventional manner from carboxylic acids (or their anhydrides) having acid functionalities of <NUM> or greater and polyols having hydroxyl functionalities of <NUM> or greater. The polyester is preferably neopentylglycol or trimethylolpropane.

In step (<NUM>), silicone precursor and polyester precursor are first reacted separately to form silicone resin and polyester resin respectively and these resins are subsequently reacted together.

The reaction temperature at which the polyester precursor or resin and the silicone precursor or resin are mixed together is preferably in the range of <NUM> to <NUM>, optionally it may be around <NUM> to <NUM>, more preferably <NUM> to <NUM>.

Preferably, the polyester precursor is formed of isophtalic acid, neopentylglycol and trimethylolpropane or trimethylolethane.

The polysiloxane-polyester block copolymer can contain condensation catalysts including metal ligand complexes or organic bases. The condensation catalysts are added to enhance the cure of the copolymer. Examples of the condensation catalysts include organotitanium compounds such as tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl titanate, titanium acetic acid salts, titanium diisopropoxybis(acetylacetonate), and titanium diisopropoxybis(ethyl acetoacetate); organozirconium compounds such as zirconium tetraacetylacetonate, zirconium hexafluoroacetylacetonate, zirconium trifluoroacetylacetonate, tetrakis(ethyltrifluoroacetylacetonate)zirconium, tetrakis(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-heptanedionate), zirconium dibutoxybis(ethylacetoacetate), and zirconium diisopropoxybis(<NUM>,<NUM>,<NUM>,<NUM>-tetramethyl-heptanedionate); and organotin compounds such as dibutyltin dilaurate, dimethyltin dineodecanoate, dibutyltin diacetate, dimethylhydroxy(oleate)tin, and dioctyldilauryltin.

The content of condensation catalyst is not limited, but it is preferably in a range of <NUM> to <NUM>,<NUM> ppm, in a range of <NUM> to <NUM> ppm, or in a range of <NUM> to <NUM> ppm, in mass unit, in the polysiloxane-polyester block copolymer. This is because excellent curability is achieved and the coating has good thermal stability.

The polysiloxane-polyester block copolymer may contain other ingredients such as organic and/or inorganic pigment like titanium oxide or barium sulfate, binder that adheres to the surface to be treated, a carrier either an organic solvent or water that carries the ingredients but evaporates when the coating is cured, or a reinforcing agent to provide wear protection. It can also contain filler like carbon black or silica, glimmer, matting agent, and release additives.

The invention extends to a coating on a substrate characterised in that the coating comprises a silicone-polyester composition as defined above. The coating may be fairly thin for example <NUM> to <NUM> and more generally from <NUM> to <NUM>, preferably from <NUM> to <NUM>. The coating may be applied in several ways to the substrate for example by spraying, curtain coating or roller coating the composition containing all ingredients.

The coating may be applied in several successive layers which may have different compositions. However preferably it is applied as a single coating layer which simplifies the process.

The invention extends to the use of the polysiloxane-polyester block copolymer as defined above to form a coating on a substrate.

The substrate is preferably made of aluminium, stainless steel, iron, plastics or glass.

The invention extends to a substrate bearing a coating characterised in that the coating comprises the polysiloxane-polyester block copolymer as defined above.

The polysiloxane-polyester block copolymer, the method for producing the same, and the use thereof of the present present invention will now be described using Practical and Comparative Examples.

A <NUM>-three necked, round bottom flask fitted with a polytetrafluoroethylene (PTFE) stirrer and N<NUM> gas purge, was loaded with a mixture of <NUM> of a silanol-terminated dimethylpolysiloxane (PDMS) represented by the following formula:.

and <NUM> of isopropyl alcohol (IPA). A pressure-equalizing addition funnel was loaded with <NUM> of methyltriacetoxysilane. The nitrogen sweep was turned on, and the methyltriacetoxysilane was added dropwise in <NUM> minutes with stirring. Then the mixture was hold at room temperature for <NUM> hours to form methyldiacetoxysilyl-terminated PDMS in IPA solvent.

A <NUM>-three necked, round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> (<NUM> moles) of phenyltriethoxysilane, <NUM> (<NUM> moles) of methyltriethoxysilane and <NUM> (<NUM> moles) of tetraethylorthosilicate. Then <NUM> of the methyldiacetoxysilyl-terminated PDMS solution (<NUM> moles of D unit) prepared by Reference Example <NUM> with <NUM> of concentrated HCl was added, and the mixture was heated slowly to <NUM>. A pressure-equalizing addition funnel was charged with <NUM> of deionized water. The nitrogen sweep was turned on. Water was added dropwise in about <NUM> minutes with stirring, and the mixture was heated to reflux for <NUM> hours. System was cooled down to <NUM>, <NUM> of CaCO<NUM> was added and hold for <NUM> hour. Mixture then heated to <NUM> and stepwise to remove volatiles and hold for <NUM> hours as well as vacuum puling for additional <NUM> hour. Finally, it was cooled down below <NUM>, filtered and drummed off. The resulting silicone resin-linear block copolymer was prepared with clear liquid appearance and having viscosity of about <NUM>,<NUM> mPa·s at <NUM>.

A <NUM>-three necked, round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> (<NUM> moles) of phenyltriethoxysilane. Then <NUM> of the methyldiacetoxysilyl-terminated PDMS solution (<NUM>. 33mol of D unit) prepared by Reference Example <NUM> with <NUM> of concentrated HCl was added, and the mixture was heated slowly to <NUM>. A pressure-equalizing addition funnel was charged with <NUM> of deionized water. The nitrogen sweep was turned on. Water was added dropwise in about <NUM> minutes with stirring, and the mixture was heated to reflux for <NUM> hours. System was cooled down to <NUM>, <NUM> of CaCO<NUM> was added and hold for <NUM> hour. Mixture then heated to <NUM> and stepwise to remove volatiles and hold for <NUM> hours as well as vacuum puling for additional <NUM> hour. Finally, it was cooled down below <NUM>, filtered and drummed off. The resulting silicone resin-linear block copolymer was prepared with clear liquid appearance and having viscosity of about <NUM>,<NUM> mPa s at <NUM>.

A <NUM>-three necked, round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> (<NUM> moles) of phenyltriethoxysilane, <NUM> (<NUM> moles) of methyltriethoxysilane and <NUM> (<NUM> moles) of tetraethylorthosilicate. Then <NUM> (<NUM> moles) of dimethyldiethoxylsilane with <NUM> of concentrated HCl was added, and the mixture was heated slowly to <NUM>. A pressure-equalizing addition funnel was loaded with <NUM> of deionized water. The nitrogen sweep was turned on. Water was added dropwise in about <NUM> minutes with stirring, and the mixture was heated to reflux for <NUM> hours. System was cooled down to <NUM>, <NUM> of CaCO<NUM> was added and hold for <NUM> hour. Mixture then heated to <NUM> and stepwise to remove volatiles and hold for <NUM> hours as well as vacuum puling for additional <NUM> hour. Finally, it was cooled down below <NUM>, filtered and drummed off. The resulting polymer was clear liquid having viscosity of about <NUM> mPa·s at <NUM>, with the random D unit distribution by using dimethyldiethoxysilane as D unit source.

A three-necked, round bottom flask fitted with a water cooled condenser, a PTFE stirrer, a thermocouple and N<NUM> gas purge was loaded with <NUM> of trimethylolpropane (TMP), <NUM> of adipic acid (AA) and <NUM> of m-phthalic acid (PA). The motrogen sweep, condenser and heating mantle were turned on. The materials were heated to <NUM>. prior to turn on the stirrer motor. Then the whole was heated to <NUM>, and hold until bulk of reaction water was removed. Periodically drain was trapped, and heated to <NUM>, until water evolution stops. The temperature was kept and some samples were taken from the mixture for testing acid value. When the acid value was less than <NUM> KOH/g, heating was turned off and cooled to <NUM>, added <NUM> of propylene glycol monomethyl ether acetate (PMA) as solvent for diluting.

A <NUM>-three necked round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> of polyester precursor prepared by Reference Example <NUM>. Then <NUM> of siloxane resin-liner block copolymer prepared by Reference Example <NUM> was added, <NUM> of propylene glycol monomethyl ether acetate (PMA) as solvent and <NUM> of tetra-n-butyl titanate as catalyst were added into flask under nitrogen surrounding. The mixture was heated slowly up to <NUM> with stirring, trap off produced ethanol. After <NUM> hours, a transparent polysiloxane-polyester copolymer was prepared. Samples were picked up and dropped on glass panel regularly to check the appearance at room temperature until clear. Heating was stopped, cooled down below <NUM>. Viscosity of prepared sample was about <NUM> mPa s at <NUM>.

A <NUM>-three necked round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> of polyester precursor prepared by Reference Example <NUM>. Then <NUM> of siloxane polymer prepared by Reference Example <NUM> was added, <NUM> of propylene glycol monomethyl ether acetate (PMA) as solvent and <NUM> of tetra-n-butyl titanate as catalyst were added into flask under nitrogen surrounding. The mixture was heated slowly up to <NUM> with stirring, trap off produced ethanol. After <NUM> hours, a transparent polysiloxane-polyester copolymer was prepared. Samples were picked up and dropped on glass panel regularly to check the appearance at room temperature until clear. Heating was stopped, cooled down below <NUM>. Viscosity of prepared sample was about <NUM>,<NUM> mPa s at <NUM>.

A <NUM>-three necked round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> of polyester precursor prepared by Reference Example <NUM>. Then <NUM> of siloxane polymer represented by the unit mole ratio of D<NUM>TPh<NUM>, with random D unit distribution, was added, <NUM> of propylene glycol monomethyl ether acetate (PMA) as solvent and <NUM> of tetra-n-butyl titanate as catalyst were added into flask under nitrogen surrounding. The mixture was heated slowly up to <NUM> with stirring, trap off produced ethanol. After <NUM> hours, a transparent polysiloxane-polyester copolymer was prepared. Samples were picked up and dropped on glass panel regularly to check the appearance at room temperature until clear. Heating was stopped, cooled down below <NUM>. Viscosity of prepared sample was about <NUM>,<NUM> mPa·s at <NUM>.

A <NUM>-three necked round bottom flask fitted with a water cooled condenser, a PTFE stirrer and a thermocouple, was loaded with <NUM> of polyester precursor prepared by Reference Example <NUM>. Then <NUM> of D unit free siloxane polymer represented by the unit formula: TMe<NUM>TPh<NUM>Q<NUM>, was added, <NUM> of propylene glycol monomethyl ether acetate (PMA) as solvent and <NUM> of tetra-n-butyl titanate as catalyst were added into flask under nitrogen surrounding. The mixture was heated slowly up to <NUM> with stirring, trap off produced ethanol. After <NUM> hours, a transparent polysiloxane-polyester copolymer was prepared. Samples were picked up and dropped on glass panel regularly to check the appearance at room temperature until clear. Heating was stopped, cooled down below <NUM>. Viscosity of prepared sample was about <NUM>,<NUM> mPa·s at <NUM>.

The appearance of the silicone-polyester copolymer at <NUM> was observed by visual inspection.

The final silicone-polyester copolymer was applied onto cleaned steel or aluminum panel for Hot Hardness and Adhesion. Thickness of the film was <NUM>±<NUM>. The coat was allowed to air drying for <NUM> minutes, and baked in oven at <NUM> for <NUM> minutes.

This test is used to rate the oil repellency performance of the coating film. Draw a random line on the surface of coating by solvent based marker pen named ZEBRA BLACK. Check the beading effect of first draw. Rating the scale according to level index of beading test. The performance is rated by the visual inspection with following Table <NUM>.

Draw a line by marker pen named ZEBRA BLACK and rub off by cotton cloth immediately. Repeat this action in the same position. Count the times up to the mark cannot be rub off completely. Make sure every time the cotton cloth is clean. Record the times until the mark can't be rub off completely.

Coated steel panels are placed on a cool hot plate. A surface thermometer is placed on the coated surface and the hot plate is turned on. As the panel temperature rises. The coatings are rated by attempting to scratch the surface with drafting pencils of increasing lead hardness. Coating hardness is rated as the highest pencil hardness that cannot scratch through the coating (higher numbers in front of the H indicate higher hardness).

Coated aluminum panels are boiled <NUM> hours in city water. Cutting the coating with <NUM> squares (each <NUM> x <NUM>), a standard tape is used to attach on the <NUM> squares and peel quickly to check if there is any square drop off. No any drop off is defined as passed. Or else, it means failed.

Claim 1:
A polysiloxane-polyester block copolymer comprising:
(i) a siloxane resin block comprising: a siloxane unit represented by the formula:
R<NUM>SiO<NUM>/<NUM>, wherein R<NUM> is a monovalent hydrocarbon group; and comprising optionally a siloxane unit represented by the formula: SiO<NUM>/<NUM>;
(ii) a siloxane linear block represented by the formula: (R<NUM><NUM>SiO<NUM>/<NUM>)n, wherein each R<NUM> is independently a monovalent hydrocarbon group, and "n" is a positive number of at least <NUM>; and
(iii) a polyester block;
wherein the polysiloxane part in the polysiloxane-polyester block copolymer contains both the siloxane resin block (i) and the siloxane linear block (ii).