CN116964166A - Coating composition - Google Patents

Abstract

The present invention relates to a coating composition comprising a blend of polyesters, said blend comprising 0.1 to 99.9 wt.% of one or more saturated polyesters (a), and 99.9 to 0.1 wt.% of one or more unsaturated polyesters (B), based on the total weight of polyesters (a) and (B); the one or more (A) and the one or more (B) have a weight average molecular weight (Mw) of at least 15,000g/mol, as determined by gel permeation chromatography using tetrahydrofuran as solvent, and a glass transition temperature of at least 60℃as determined by differential scanning calorimetry according to DIN EN 61006 method A. The invention also relates to a high molecular weight polyester per se, to a process for the preparation of a coated substrate, to the coated substrate per se, and to the use of the coating composition.

Description

Coating composition

Technical Field

The present invention relates to a coating composition comprising a blend of high molecular weight polyesters and to the high molecular weight polyesters themselves. The invention also relates to a method for producing a coated substrate, the coated substrate itself, and the use of the coating composition.

Background

In addition to aesthetic reasons, coatings are intended to protect substrates from damaging effects that may intentionally or unintentionally affect them. Coatings should meet a wide range of specific properties associated with resistance to heat, ultraviolet radiation, chemicals, mechanical forces, and the like.

It was confirmed that the coating was applied to the metal substrate to delay or inhibit corrosion.

The coatings are typically applied to a wide variety of substrates using any suitable procedure such as spraying, roll coating, curtain coating, dip coating, etc. as a liquid or using a fluidized bed or electrostatic deposition such as corona or spray gun, etc. as a solid. In the particular case of coating a metal sheet or coil with a coating, the coating may be applied by roll coating.

Typical application of the coating involves the interior and optionally the exterior of a (light) metal package, more particularly a metal can body and can end, in order to prevent the contents of the can from contacting the metal. Contact between the metal and the packaged product can cause corrosion of the metal, which can contaminate the packaged product.

Coating compositions for the inside of beer, beverage and food cans must be approved for direct food contact. The primary function of the can body and the interior coating on the can end (see, e.g., "Polymeric Materials Science and Engineering", volume 65, autumn conference 1991, new york, pages 277-278) is to preserve the packaged product for nutritional value, texture, color and flavor when purchased and used by the consumer. To meet these requirements, the organic film must be free of any materials that may be extracted into the packaged product and must maintain its integrity for the recommended shelf life of the product.

Many of the coating compositions for food and beverage containers are based on polyether resins based on polyglycidyl ethers of bisphenol a. Bisphenol a (bisphenol a itself or derivatives thereof, such as diglycidyl ether of bisphenol a, epoxy novolac resins, and polyols prepared from bisphenol a and bisphenol F) in container coatings is problematic. Trace amounts of bisphenol a diglycidyl ether from the epoxy resin coating material ooze out of the inner coating of the holding tank and are absorbed by human organs along with the food. In fact, in oil-containing fish cans, impermissibly high concentrations of bisphenol A diglycidyl ether exuded from the inner coating have been measured. It is now suspected that the ingestion of bisphenol a diglycidyl ether into human organs can bring about carcinogenic and estrogenic effects. While the balance of scientific evidence available to date suggests that trace amounts of bisphenol a or bisphenol a diglycidyl ether that may be released from existing coatings are not a health risk to humans, some consider these compounds to be detrimental to human health. Therefore, it is strongly desired to remove these compounds from coatings for food and beverage containers. Accordingly, can coating compositions for food and beverage containers that do not contain an extracted amount of bisphenol a, bisphenol a diglycidyl ether, or other derivatives of bisphenol a, and that also have commercially acceptable properties are desired.

Coatings for food and beverage containers should preferably be capable of being applied to a substrate at high speeds, such as in a roll coating or sheet coating operation, and provide the desired properties upon curing. The coating should generally be capable of maintaining suitable film integrity during container manufacture and of withstanding the processing conditions to which the container may be subjected during product packaging. The pre-coated metal sheet is subjected to severe tensile and compressive stresses during the can forming process. The integrity of the coating must be maintained during all specific manufacturing operations.

To address the shortcomings of currently applied coating formulations, the packaging coating industry has sought coatings based on alternative binder systems such as polyester resin systems. However, formulating polyester-based coatings that exhibit a desired balance of coating properties (e.g., flexibility, adhesion, solvent resistance, sterilization resistance, etc.) is problematic.

Polyester-based coatings for the interior surfaces and can ends of cans are disclosed in many prior art documents.

US4,452,954 (a) discloses a coating comprising a polymer having a backbone comprising ester and urethane linkages and one or more polycyclic groups comprising saturated bicyclic groups, aromatic bicyclic groups, at least tricyclic groups, or a combination thereof, wherein the polymer is formed via the reaction of a polyisocyanate compound and a hydroxy-functional polyester oligomer or polymer having a hydroxyl number of 25-200.

EP2416962B1 discloses a coating composition comprising a binder polymer and a resole crosslinker, the binder polymer having one or more backbone unsaturated cycloaliphatic groups comprising a double bond between carbon atoms of the ring and an Iodine Value of at least 10, wherein the unsaturated cycloaliphatic groups comprise unsaturated groups that are at least bicyclic, wherein the Iodine Value is measured by test method E "Iodine Value".

US10,563,010B2 discloses a coating composition comprising an unsaturated polyester polymer having an iodine value of at least 10; wherein the polyester polymer comprises an ether linkage, or the coating composition comprises a metal drier, or the polyester polymer comprises an ether linkage and the coating composition comprises a metal drier.

US9,200,176B2 discloses a coating composition comprising a polyester polymer having a backbone or pendant unsaturated monocyclic cycloaliphatic groups.

US8,449,960B2 discloses a coating composition comprising a binder polymer having a glass transition temperature of at least 25 ℃, a backbone or pendant unsaturated at least bicyclic group comprising a double bond between carbon atoms of the ring, and an iodine value of at least about 10, and a crosslinker.

US8,168,276B2 discloses a coating prepared from a composition, wherein the composition comprises a resin system comprising carboxyl groups, hydroxyl groups, or a combination thereof, a crosslinker comprising a phenolic crosslinker, an amino crosslinker, or a combination thereof, and a catalyst comprising a titanium-containing catalyst, a zirconium-containing catalyst, or a combination thereof; wherein the composition is substantially free of bisphenol a.

WO2016/073711 (A1) discloses a thermosetting composition comprising a curable polyester resin and a crosslinker composition comprising a resole resin containing residues of unsubstituted phenol and/or meta-substituted phenol.

US7,144,975B2 an unsaturated, amorphous polyester is disclosed which comprises at least one alpha, beta-unsaturated dicarboxylic acid component and an alcohol component, wherein the alcohol component comprises the isomeric compound 3, 8-bis (hydroxymethyl) tricyclo [5.2.1.0 ^{2 ,6} ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A glycol mixture of decane, wherein each isomer may be present in the mixture in a proportion of 20-40% and the sum of the three isomers is 90-100%, and at least 5% of the mixture is present in the alcohol component of the polyester. The unsaturated polyester resins of the examples are characterized by having an acid number of about 25mg KOH/g, a hydroxyl number of about 36mg KOH/g, a glass transition temperature of 12℃or less and a weight average molecular weight of 5,500 or less.

WO 2009/01363 A1 discloses non-yellowing, low viscosity, unsaturated, amorphous polyesters consisting of an acid component comprising 10 to 100mol% of at least one alpha, beta-unsaturated dicarboxylic acid and 0 to 90mol% of at least one linear and/or branched aliphatic and/or cycloaliphatic and/or aromatic di-and/or multifunctional carboxylic acid and an alcohol component comprising 5 to 100mol% of a glycol mixture and 0 to 95mol% of at least one di-and/or multifunctional alcohol. The polyester is characterized by a glass transition temperature of-30 ℃ to +90 ℃ and a weight average molecular weight of 900-27,000, preferably 1,000-15,000g/mol.

US6,143,841 (a) discloses a coating formulation consisting of:

a) Thermoplastic base polyesters consisting of the copolymerization products of at least one aliphatic, cycloaliphatic and/or aromatic polyacid and/or anhydride thereof or of at least one hydroxycarboxylic acid or derivative thereof and at least one glycol;

b) An unsaturated additive polyester resin prepared by condensing at least one unsaturated dicarboxylic acid and optionally at least one saturated dicarboxylic acid monomer with at least one diol and/or triol, wherein the ratio of unsaturated additive polyester to base polyester is from 0.1 to 15 parts to 99.9 to 85 parts; and

c) At least one substance selected from the group consisting of: color pigments, fillers, stabilizers, leveling agents and gloss agents.

The diol used to prepare the unsaturated additive polyester is 3 (4), 8 (9) bis- (hydroxymethyl) tricyclo- (5,2,10,2,6) decane; the unsaturated dicarboxylic acid monomers used to prepare the unsaturated additive polyesters are maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid and/or tetrahydrophthalic acid. The base polyester has a glass transition temperature of 10 to 40 ℃ and a melting range of 160 to 180 ℃.

Polyester-based coating systems (substantially free of bisphenol) typically lack one or more film properties compared to coating systems based on polyether resins comprising (or made from) polyglycidyl ethers of bisphenol.

Object of the Invention

The object of the present invention is to provide a coating composition which does not have the disadvantages of the prior art.

It is an object of the present invention to provide a coating composition having improved solvent resistance, substrate adhesion and flexibility.

It is a further object of the present invention to provide a coating composition for coils and cans.

It is another object to provide a can coating composition that exhibits a combination of properties equal to or better than the prior art products on the market, while avoiding HSE/FDA suspected substances such as bisphenol a, bisphenol F, formaldehyde and isocyanate.

Summary of The Invention

A coating composition comprising a blend of polyesters, the blend comprising:

from 0.1 to 99.9% by weight of one or more saturated polyesters (A), and

99.9 to 0.1% by weight of one or more unsaturated polyesters (B),

based on the total weight of polyesters (A) and (B);

the one or more (A) and the one or more (B) have a weight average molecular weight (Mw) of at least 15,000g/mol, as determined by gel permeation chromatography using tetrahydrofuran as solvent, and a glass transition temperature of at least 60℃as determined by differential scanning calorimetry according to DIN EN 61006 method A.

Preferably, one or more of (a) and/or one or more of (B) comprises an aliphatic cyclic group.

Preferred embodiments of the invention disclose one or more of the following features:

-one or more (a) and/or one or more (B) comprise an aliphatic bicyclic group and/or a tricyclic group, preferably an aliphatic tricyclic group;

-one or more (a) and/or one or more (B) are obtained from the esterification of a polycarboxylic acid (and/or anhydride) and a polyol comprising one or more aliphatic polycyclic diols selected from the group consisting of: bicyclic diols, tricyclic diols, and mixtures thereof;

one or more of (a) and/or (B) is/are preferably obtained from the esterification of a polycarboxylic acid and a polyol comprising an aliphatic tricyclic diol selected from the group consisting of: 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^{2 ,6} ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, and mixtures thereof;

-one or more (B) comprises one or more unsaturated dibasic acids or anhydrides selected from: α, β -unsaturated dicarboxylic acids, α, β -unsaturated anhydrides, unsaturated dibasic acids comprising isolated ethylenically unsaturated double bonds, unsaturated anhydrides comprising isolated ethylenically unsaturated double bonds, and mixtures thereof;

-the coating composition comprises 35-50wt% of a blend comprising one or more (a) and one or more (B), and 50-65wt% of one or more organic solvents selected from the group consisting of: aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, glycols, glycol ethers, glycol esters, and mixtures thereof;

The invention also discloses a method of preparing a coated metal substrate comprising the steps of:

-applying the coating composition onto at least one side of the optionally pretreated and/or primer-containing metal substrate at a coating thickness adjusted so as to obtain a dry coating (or dry film) thickness of less than 60 μm;

-baking the applied coating composition at a temperature of at least 150 ℃ for a time of at least 20 seconds, thereby forming a metal substrate coated with a crosslinked coating;

the invention also discloses a method of making a coated can body and can end comprising the steps of:

-cutting the coated metal substrate into metal pieces of a desired size and shape to form a can body and a can end ready for assembly; or alternatively

-cutting the coated metal substrate into metal pieces of the desired size and shape, stamping the metal pieces into cans, and cutting the can ends into the desired shape ready for assembly.

Detailed Description

The coating formulation (or coating composition) according to the invention comprises a blend of one or more saturated polyesters (a) and one or more unsaturated polyesters (B), said blend comprising:

from 0.1 to 99.9% by weight, preferably from 0.5 to 99.5% by weight, more preferably from 1 to 99% by weight, even more preferably from 5 to 95% by weight, still even more preferably from 10 to 90% by weight, still even more preferably from 15 to 85% by weight, or even from 20 to 80% by weight, most preferably from 35 to 80% by weight of one or more saturated polyesters (A); and

-99.9 to 0.1wt%, preferably 99.5 to 0.5wt%, more preferably 99 to 1wt%, even more preferably 95 to 5wt%, still even more preferably 90 to 10wt%, still even more preferably 85 to 15wt%, or even 80 to 20wt%, most preferably 65 to 20wt% of one or more unsaturated polyesters (B);

based on the total weight of polyesters (A) and (B).

Preferably, the one or more saturated polyesters (a) and/or the one or more unsaturated polyesters (B) comprise one or more aliphatic cyclic groups in the polyester backbone, more preferably the one or more saturated polyesters (a) and/or the one or more unsaturated polyesters (B) comprise 10 to 70 wt. -%, even more preferably 15 to 65 wt. -%, still even more preferably 20 to 60 wt. -%, most preferably 25 to 60 wt. -% of the one or more aliphatic cyclic groups.

More preferably, the one or more saturated polyesters (a) and the one or more unsaturated polyesters (B) each comprise one or more aliphatic cyclic groups in the polyester backbone, even more preferably the one or more saturated polyesters (a) and the one or more unsaturated polyesters (B) each comprise 10 to 70wt%, still even more preferably 15 to 65wt%, or even 20 to 60wt%, most preferably 25 to 60wt% of the one or more aliphatic cyclic groups.

The aliphatic cyclic group of the present invention refers to an aliphatic monocyclic or aliphatic polycyclic group.

The aliphatic monocyclic group of the present invention refers to a C4-C6 cyclic group, optionally alkyl-substituted and/or optionally containing one or more heteroatoms (e.g., wherein in the C4-C6 cyclic group one or more hydrocarbons (-CH) ₂ (-) is replaced by a heteroatom and/or wherein the C4-C6 cyclic group has a substituent comprising a heteroatom).

The aliphatic monocyclic group is preferably incorporated into the polyester backbone by esterification of an aliphatic monocyclic diol (e.g., 1, 4-cyclohexanedimethanol, 2, 4-tetramethyl-1, 3-butanediol and/or 1, 4-cyclohexanediol) and/or a monocyclic dicarboxylic acid and/or anhydride (e.g., 1, 2-cyclohexanedicarboxylic acid or its anhydride, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid), preferably in the presence of a polyhydric alcohol and a polycarboxylic acid.

Preferably, the aliphatic polycyclic group is an aliphatic bicyclic group and/or an aliphatic tricyclic group, more preferably an aliphatic tricyclic group.

Preferably, the aliphatic polycyclic group does not contain an ethylenically unsaturated double bond in the polycyclic ring structure.

The aliphatic tricyclic diol is preferably selected from 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ] ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, and mixtures thereof (mixtures thereof are referred to as TCD-diols).

Preferably, the aliphatic tricyclic diol comprises at least one aliphatic tricyclic compound, more preferably the aliphatic tricyclic diol comprises a mixture of at least two aliphatic tricyclic compounds.

The aliphatic bicyclic diol is preferably an aliphatic heterobicyclic diol selected from the group consisting of: isosorbide, isomannide, isoidide and derivatives thereof.

In the present specification, the expression "aliphatic heterobicyclic diol" refers to an aliphatic bicyclic diol having a cycloaliphatic ring, wherein the ring comprises at least one heteroatom, i.e. wherein in the ring one or more hydrocarbons (-CH) ₂ (-) is replaced by a heteroatom (e.g., oxygen).

Preferably, the aliphatic bicyclic diol comprises at least one aliphatic bicyclic diol, more preferably the aliphatic bicyclic diol comprises a mixture of at least two aliphatic bicyclic diols.

The aliphatic polycyclic groups are preferably incorporated into the polyester backbone by esterification of aliphatic polycyclic diols with polycarboxylic acids and/or anhydrides and polyols.

Optionally, aliphatic polycyclic groups are incorporated into the polyester backbone by esterification of a mixture comprising one or more aliphatic bicyclic diols and one or more aliphatic tricyclic diols with polycarboxylic acids and/or anhydrides and polyols.

Preferably, the one or more saturated polyesters (a) are the reaction product of:

an acid component comprising 50 to 100mol%, preferably 60 to 100mol%, more preferably 70 to 100mol%, most preferably 80 to 100mol% of an aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and mixtures thereof, and 0 to 50mol%, preferably 0 to 40mol%, more preferably 0 to 30mol%, most preferably 0 to 20mol% of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or their anhydrides, and

a glycol component comprising 5 to 30mol%, preferably 10 to 25mol%, of one or more aliphatic and/or cycloaliphatic diols and 70 to 95mol%, preferably 75 to 90mol%, of one or more aliphatic polycyclic diols,

the one or more saturated polyesters (A) have a weight average molecular weight of at least 15,000g/mol, determined by gel permeation chromatography using tetrahydrofuran as solvent, and a glass transition temperature of at least 60℃as determined by differential scanning calorimetry according to DIN EN 61006 method A.

More preferably, the one or more saturated polyesters (a) are the reaction product of:

an acid component comprising 50 to 100mol%, preferably 60 to 100mol%, more preferably 70 to 100mol%, most preferably 80 to 100mol% of an aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and mixtures thereof, and 0 to 50mol%, preferably 0 to 40mol%, more preferably 0 to 30mol%, most preferably 0 to 20mol% of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or their anhydrides, and

-a glycol component comprising 5-30mol%, preferably 10-25mol% of one or more aliphatic and/or cycloaliphatic diols, and 70-95mol%, preferably 75-90mol% of one or more aliphatic polycyclic diols;

wherein:

-the saturated aliphatic dibasic acid is selected from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and mixtures thereof;

-the saturated cycloaliphatic diacid is selected from the group consisting of 1, 2-cyclohexanedicarboxylic acid or its anhydride, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid and mixtures thereof;

-the aromatic diacid is selected from the group consisting of phthalic acid, 2, 6-naphthalene dicarboxylic acid, 2, 7-naphthalene dicarboxylic acid and mixtures thereof;

and wherein:

-aliphatic diols are selected from ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 2-ethyl-2-butyl-1, 3-propanediol, 2-methyl-1, 3-propanediol, neopentyl glycol hydroxytrimethacetate and mixtures thereof;

-the cycloaliphatic diol is selected from the group consisting of 1, 4-cyclohexanedimethanol, 2, 4-tetramethyl-1, 3-butanediol, 1, 4-cyclohexanediol and mixtures thereof.

Even more preferably, the one or more saturated polyesters (A) are terephthalic acid as dicarboxylic acid component, 1, 4-butanediol as aliphatic diol component and 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane as lipidReaction products of a group polycyclic diol component.

Preferably, the one or more unsaturated polyesters (B) are the reaction product of:

an acid component comprising 50 to 90mol%, preferably 60 to 85mol%, of an aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and mixtures thereof, 10 to 50mol%, preferably 15 to 40mol%, of one or more unsaturated dibasic acids or anhydrides thereof, and 0 to 30mol%, preferably 0 to 20mol%, of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or anhydrides thereof, and

a glycol component comprising 5 to 30mol%, preferably 10 to 25mol%, of one or more aliphatic and/or cycloaliphatic diols and 70 to 95mol%, preferably 75 to 90mol%, of one or more aliphatic polycyclic diols,

the one or more unsaturated polyesters (B) have a weight average molecular weight of at least 15,000g/mol, determined by gel permeation chromatography using tetrahydrofuran as solvent, and a glass transition temperature of at least 60℃as determined by differential scanning calorimetry according to DIN EN 61006 method A, and an unsaturated equivalent weight of 300-6,000 g/equivalent.

More preferably, the one or more unsaturated polyesters (B) are the reaction products of:

an acid component comprising 50 to 90mol%, preferably 60 to 85mol%, of an aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and mixtures thereof, 10 to 50mol%, preferably 15 to 40mol%, of one or more unsaturated dibasic acids or anhydrides thereof, and 0 to 30mol%, preferably 0 to 20mol%, of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or anhydrides thereof, and

-a glycol component comprising 5-30mol%, preferably 10-25mol% of one or more aliphatic and/or cycloaliphatic diols, and 70-95mol%, preferably 75-90mol% of one or more aliphatic polycyclic diols;

wherein:

-the saturated aliphatic dibasic acid is selected from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and mixtures thereof;

-the saturated cycloaliphatic diacid is selected from the group consisting of 1, 2-cyclohexanedicarboxylic acid or its anhydride, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid and mixtures thereof;

-the aromatic diacid is selected from the group consisting of phthalic acid, 2, 6-naphthalene dicarboxylic acid, 2, 7-naphthalene dicarboxylic acid and mixtures thereof;

-one or more unsaturated dibasic acids or anhydrides selected from the group consisting of maleic acid, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, tetrahydrophthalic acid, 5-norbornene-2, 3-dicarboxylic acid (also known as nadic acid), methylnadic acid, or anhydrides thereof and mixtures thereof;

And wherein:

-aliphatic diols are selected from ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, 2-ethyl-2-butyl-1, 3-propanediol, 2-methyl-1, 3-propanediol, neopentyl glycol hydroxytrimethacetate and mixtures thereof;

-the cycloaliphatic diol is selected from the group consisting of 1, 4-cyclohexanedimethanol, 2, 4-tetramethyl-1, 3-butanediol, 1, 4-cyclohexanediol and mixtures thereof.

Even more preferably, the one or more unsaturated polyesters (B) are terephthalic acid as dicarboxylic acid component, maleic anhydride and/or fumaric acid as unsaturated dicarboxylic acid component, 1, 4-butanediol as aliphatic diol component and 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A blend (mixture) of decanes as the reaction product of aliphatic polycyclic diol components.

Optionally, terephthalic acid and/or isophthalic acid in the one or more polyesters (A) and/or the one or more polyesters (B) may be replaced completely or partially by 2, 5-furandicarboxylic acid, wherein partial replacement is understood to mean that 5 to 95mol% of terephthalic acid and/or isophthalic acid is replaced by 95 to 5mol% of 2, 5-furandicarboxylic acid.

The one or more polyesters (a) and the one or more unsaturated polyesters (B) each have a weight average molecular weight (Mw) of at least 15,000g/mol, determined by gel permeation chromatography using tetrahydrofuran as solvent, and a polydispersity (dpi=mw/Mn) of preferably at least 2.

Preferably, the weight average molecular weight (Mw) of the one or more polyesters (a) and the one or more unsaturated polyesters (B) are each between 15,000 and 50,000g/mol, more preferably between 20,000 and 50,000g/mol, even more preferably between 20,000 and 45,000g/mol, still even more preferably between 25,0000 and 45,000g/mol, still even more preferably between 25,000 and 40,000g/mol, most preferably between 25,000 and 35,000g/mol, and preferably the polydispersity (dpi=mw/Mn) is between 2 and 6, more preferably between 2 and 5.5, even more preferably between 2 and 5.3.

The one or more polyesters (a) and the one or more unsaturated polyesters (B) each have a glass transition temperature of at least 60 ℃, preferably at least 70 ℃, more preferably from 80 to 130 ℃, even more preferably from 90 to 120 ℃, most preferably from 95 to 120 ℃, as determined by differential scanning calorimetry according to DIN EN 61006 method a, wherein any one of the one or more (a) and the one or more (B) satisfies the glass transition temperature range or wherein a blend of the one or more (a) and the one or more (B) satisfies the glass transition temperature range.

Preferably, the one or more saturated polyesters (A) and the one or more unsaturated polyesters (B) have an intrinsic viscosity in chloroform of from 10 to 50ml/g, preferably from 15 to 45ml/g, more preferably from 20 to 40ml/g, determined in accordance with DIN 51562 T1; wherein any one of the one or more (a) and the one or more (B) has the range of intrinsic viscosity, or wherein a blend of the one or more (a) and the one or more (B) has the range of intrinsic viscosity.

The one or more unsaturated polyesters (B) also have an unsaturated equivalent weight of 300 to 6,000 g/equivalent, preferably 500 to 4,000 g/equivalent, more preferably 500 to 2,000 g/equivalent, most preferably 700 to 1,600 g/equivalent.

One or more saturated polyesters (a) and/or one or more unsaturated polyesters (B) are prepared in a single or multi-step condensation process comprising:

-adding one or more dicarboxylic acids to 5-15% stoichiometric excess of one or more diols, and

-carrying out the reaction using reflux distillation at a temperature of at least 170 ℃ to 250 ℃ under nitrogen purge in the presence of an azeotropic hydrocarbon solvent and an esterification catalyst until an acid number of less than 5mg KOH/g is obtained.

Preferably, the one or more polyesters (A) are prepared in a single step process in which a stoichiometric excess of one or more diols, one or more diacids are reacted with an azeotropic hydrocarbon solvent and an esterification catalyst at a temperature of 225-250 ℃ until an acid number of less than 5mg KOH/g, preferably less than 4mg KOH/g, more preferably less than 3mg KOH/g is reached. Optionally, for the particular case where the desired molecular weight is not obtained, small amounts of saturated aliphatic acids and/or aromatic dicarboxylic acids and/or their anhydrides are added, followed by continued condensation until an acid number of less than 5mg KOH/g, preferably less than 4mg KOH/g, more preferably less than 3mg KOH/g, is reached.

Preferably, the one or more unsaturated polyesters (B) are prepared in a two-step process in which a stoichiometric excess of one or more diols, one or more diacids are reacted with an azeotropic hydrocarbon solvent and an esterification catalyst at a temperature of 225-250 ℃ until an acid number of less than 5mg KOH/g, preferably less than 4mg KOH/g, more preferably less than 3mg KOH/g, is reached. Subsequently, the reaction mixture is cooled to a temperature of 170-190 ℃, followed by the addition of one or more alpha, beta-unsaturated dicarboxylic acids or their anhydrides and/or one or more dicarboxylic acids or their anhydrides comprising isolated ethylenically unsaturated double bonds, followed by continued condensation at a temperature between 170-190 ℃ until an acid number of less than 5mg KOH/g, preferably less than 4mg KOH/g, more preferably less than 3mg KOH/g is obtained.

Examples of esterification catalysts used are tin derivatives, such as dibutyltin dilaurate, dibutyltin oxide, monobutyltin oxide or n-butyltin trioctoate, or titanium derivatives, such as titanium tetrabutoxide (also known as tetrabutyl titanate, butyl titanate or butoxytitanium). Preferred catalysts for the preparation of the polyesters of the invention are tin derivatives.

0 to 1% of phenol derivatives can be used, for example 1010 (BASF) either alone or in a mixture with various stabilizers at any step of the reaction (i.e., at the beginning of polyesterification,During or at the end) of the esterification reaction, such as those of the phosphite type, for example trialkyl phosphites (WESTON) ^TM )。

The one or more saturated polyesters (a) and the one or more unsaturated polyesters (B) are preferably diluted with a suitable solvent to obtain the desired viscosity for liquid coating applications.

Suitable organic solvents include aliphatic hydrocarbons (e.g., mineral spirits, kerosene, high flash point VM & P naphtha, etc.), aromatic hydrocarbons (e.g., toluene, xylene, solvent naphtha 100, 150, 200, etc.), alcohols (e.g., ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc.), ketones (e.g., acetone, 2-butanone, cyclohexanone, methyl aryl ketone, ethyl aryl ketone, methyl isoamyl ketone, etc.), esters (e.g., ethyl acetate, butyl acetate, etc.), glycols (e.g., butylene glycol), glycol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, methoxypropanol, etc.), glycol esters (e.g., butylene acetate, methoxypropyl acetate, etc.), and mixtures thereof.

Preferred organic solvents include aliphatic hydrocarbons, aromatic hydrocarbons, glycol ethers, and mixtures thereof.

Adding one or more additives selected from the following to a mixture comprising one or more saturated polyesters (a) and one or more unsaturated polyesters (B): carriers, additional polymers, emulsifiers, pigments, metal powders or slurries, fillers, anti-migration aids, biocides, extenders, lubricants, coalescing agents, wetting agents, biocides, plasticizers, crosslinking agents, crosslinking catalysts, defoamers, colorants, waxes, antioxidants, anticorrosion agents, flow control agents, thixotropic agents, dispersants, adhesion promoters, UV stabilizers and scavengers, in order to obtain a coating formulation.

Optionally, the coating formulation of the present invention comprises one or more additional crosslinkers. Any suitable crosslinking agent or combination of crosslinking agents may be used. For example, phenolic crosslinkers (e.g., phenolics), amino crosslinkers (e.g., aminoplasts), blocked isocyanate crosslinkers, epoxy-functional crosslinkers, and combinations thereof may be used. Preferred crosslinking agents are at least substantially free, more preferably completely free of bound bisphenol A and aromatic diglycidyl ether.

When additional crosslinking agents are used in the coating formulation of the present invention, it is preferred to use phenolic crosslinking agents.

Examples of suitable phenolic crosslinkers include the reaction products of aldehydes with phenols. Formaldehyde and acetaldehyde are preferred aldehydes. Non-limiting examples of suitable phenols that may be used include phenol, cresol, p-phenylphenol, p-t-butylphenol, p-t-pentylphenol, cyclopentylphenol, creosoic acid, and combinations thereof.

When present, the concentration of one or more optional crosslinkers in the coating formulation can vary depending on the desired result. For example, in some embodiments, the coating composition may comprise from 0.01 to 50wt%, preferably from 5 to 50wt%, more preferably from 10 to 40wt%, most preferably from 15 to 30wt% of one or more crosslinking agents, based on the total weight of the one or more saturated polyesters (a), the one or more unsaturated polyesters (B), and the one or more crosslinking agents.

For the particularly optional case of using an additional crosslinker, the coating composition preferably comprises:

-35-50wt% of a mixture comprising:

50 to 95% by weight of one or more saturated polyesters (A) and one or more unsaturated polyesters (B), and

5-50wt% of one or more crosslinking agents, and

-50-65wt% of one or more organic solvents.

Preferably, the use of additional crosslinker is omitted entirely (i.e. the coating formulation of the invention comprises 0.0% crosslinker).

Optionally, a crosslinking catalyst is added.

Suitable crosslinking catalysts are peroxides, hydroperoxides, peresters, metal catalysts, strong acids, tertiary and quaternary ammonium compounds, phosphorus compounds, sulfur-containing compounds, and combinations thereof. More particularly, a metal catalyst is optionally added.

Suitable metal catalysts are selected from the group consisting of aluminum (Al), antimony (Sb), barium (Ba), bismuth (Bi), calcium (Ca), cerium (Ce), chromium (Cr), cobalt (Co), copper (Cu), iridium (Ir), iron (Fe), lead (Pb), lanthanum (La), lithium (Li), manganese (Mn), neodymium (Nd), nickel (Ni), rhodium (Rh), ruthenium (Ru), palladium (Pd), potassium (K), osmium (Os), platinum (Pt), sodium (Na), strontium (Sr), tin (Sn), titanium (Ti), vanadium (V), yttrium (Y), zinc (Zn), and zirconium (Zr) and salts or complexes thereof, preferably, suitable metal catalysts are titanium, iron or manganese, more preferably subway or manganese (or salts or complexes thereof). In this specification, the expression "metal catalyst" means "metal crosslinking catalyst".

If used, the crosslinking catalyst is preferably present in an amount of from 0.01 to 3wt%, more preferably in an amount of from 0.1 to 1.0wt%, based on the weight of nonvolatile material in the coating composition.

More preferably, in the coating formulation of the present invention, the addition of the crosslinking catalyst is omitted entirely (i.e. the coating formulation of the present invention comprises 0.0% of the crosslinking catalyst).

According to one embodiment, when the one or more unsaturated polyesters comprise α, β -unsaturated ester moieties, preferably obtained from esterification of maleic anhydride and/or fumaric acid, the amount of metal catalyst is low, preferably less than 0.1wt%, more preferably less than 0.001wt%, based on the weight of non-volatile materials in the coating composition. Most preferably no metal catalyst is added (i.e., the coating formulation of the present invention comprises 0.0% metal catalyst).

Furthermore, the organometallic and/or organometalloid compounds may be added to the coating composition as adhesion promoters in amounts of up to 1.5wt%, preferably up to 1.2wt%, more preferably up to 0.9wt%, based on the weight of non-volatile materials in the coating composition.

Suitable adhesion promoting compounds are selected from the group consisting of titanates, zirconates, silanes, and mixtures thereof.

Preferably, the titanate is selected from tetraalkyl titanates; more preferably the tetraalkyl titanate is tetrabutyl titanate.

Preferably, the zirconate is selected from tetraalkyl zirconates; more preferably the tetraalkyl zirconate is tetrabutyl zirconate.

Preferably, the silane is selected from functionalized di-or trialkoxysilanes; more preferably the functionalized di-or trialkoxysilane is a di-or trimethoxysilane comprising acrylate, amino or epoxy functional groups, such as methacryloxypropyl methyl dimethoxy silane, aminopropyl trimethoxysilane, (2-aminoethyl) -3-aminopropyl-trimethoxysilane, 3-glycidoxypropyl trimethoxysilane.

Preferably the coating composition comprises at least 0.05wt%, more preferably at least 0.1wt% of adhesion promoter based on the weight of non-volatile materials in the coating composition. More preferably, the coating composition comprises from 0.05 to 1.5wt%, even more preferably from 0.1 to 1.5wt%, most preferably from 0.1 to 1.2wt% of the adhesion promoter, based on the weight of non-volatile materials in the coating composition.

Preferably, the coating composition comprises from 0.05 to 1.5wt%, even more preferably from 0.1 to 1.5wt%, most preferably from 0.1 to 1.2wt% of the tetraalkyl titanate, more preferably tetrabutyl titanate, based on the weight of the non-volatile materials in the coating composition.

According to another embodiment, when the one or more unsaturated polyesters comprise isolated ethylenically unsaturated double bonds, preferably obtained from esterification of an unsaturated dibasic acid or anhydride thereof (e.g., tetrahydrophthalic acid, nadic acid, or methylnadic acid or anhydride thereof) comprising isolated ethylenically unsaturated double bonds, the metal catalyst is preferably present in an amount of at least 0.01wt%, more preferably 0.01 to 3wt%, most preferably 0.1 to 1.0wt%, based on the weight of nonvolatile material in the coating composition, more preferably iron or manganese (or salt or complex thereof).

Preferably, the coating composition of the present invention comprises less than 10,000ppm, more preferably less than 5,000ppm, even more preferably less than 1,000ppm, even more preferably less than 500ppm, still even more preferably less than 100ppm, or even less than 50ppm, most preferably less than 20ppm of an ingredient selected from the group consisting of: bisphenol-a (NI) (i.e., bisphenol-a is not intended), formaldehyde, isocyanate, and mixtures thereof.

The coating composition of the present invention can be applied to a substrate using any suitable procedure such as spray coating, roll coating, coil coating, curtain coating, dip coating, electrostatic deposition coating, and the like, as well as other types of pre-measured coating. In one embodiment, where a coating is used to coat a metal sheet or coil, the coating may be applied by roll coating.

In the present invention, the term "tank" refers to various tanks, such as a two-part tank, a three-part tank, or an integral tank.

The coating composition of the present invention may be applied to a variety of substrates selected from the group consisting of: metals, glass, polymers (e.g., polyimide-amide, polyetherketone, polyethersulfone, polyphenylsulfone, or polybenzimidazole), composites, concrete, ceramics, and engineered wood (e.g., medium density fiberboard or high density fiberboard, particle board, or oriented strand board) so long as the substrate is resistant to bake cycle conditions.

The coating composition of the present invention may be applied to at least one side of a substrate, preferably on both sides of a substrate.

Preferably, the substrate is a metal substrate, more preferably a tin plate, tin-free steel or aluminum substrate.

Preferably, the coating formulation is applied in a thickness such that the resulting coating after curing has a dry film thickness of less than 60 μm, preferably less than 30 μm, more preferably between 3-20 μm, even more preferably between 5-15 μm, most preferably between 8-12 μm.

Solvent evaporation and curing of the coating may be carried out in an air-vented convection oven at a temperature of at least 150 ℃, preferably 150-250 ℃, more preferably 170-230 ℃, even more preferably 180-220 ℃, most preferably 190-210 ℃ for a time of at least 20 seconds, preferably 1-25 minutes, more preferably 2-22 minutes, even more preferably 5-20 minutes, still even more preferably 8-18 minutes, most preferably 10-15 minutes.

Alternatively, the coating may be cured by infrared radiation, such as near infrared, short infrared or mid infrared radiation, or by induction or by a combination thereof. In embodiments using infrared or induction systems, the toasting cycle is in the range of 2-160 seconds, depending on the heating system or combination of heating systems.

It is well within the practice of those skilled in the art to find suitable combinations of baking temperatures and times.

The coating formulation of the present invention is preferably used in coil coating applications comprising the steps of:

-unwinding a roll of metal substrate;

-applying the coating formulation of the invention to at least one side of the expanded metal substrate with a suitable coating thickness;

baking the applied coating formulation by means of a suitable heating system, thereby forming a metal substrate coated with a crosslinked coating; and

-rewinding the metal substrate to form a roll of metal substrate comprising the crosslinked coating.

The metal substrate is preferably pretreated and/or primed prior to application of the coating. In one embodiment, the metal substrate roll (as supplied by the supplier) is pre-treated and/or primed.

The coating formulation of the present invention is preferably used for (light) metal packaging, more particularly for can coating applications, comprising the steps of:

-unwinding a coated metal substrate roll coated with a cured coating formulation of the invention;

-cutting the can body and can end into a desired shape to produce a three-piece can; or alternatively

-stamping a metal piece into a can body and cutting the can end into a desired shape to produce a two-piece can;

-assembling a can body and one or more can ends.

Preferably the outer surface of the can comprises one or more printings.

Preferably the cans are intended for food and beverage applications.

When used in a coil or can coating application, the interior and/or exterior of the coil or can may be coated with the coating composition of the present invention.

Preferably, the interior and exterior of the coil or can are coated with the coating composition of the present invention.

Coatings obtained using the coating compositions of the present invention have good coating properties, more particularly improved solvent resistance (compared to when using coating compositions already described in the prior art so far) without losing their flexibility. In fact, the coatings obtained using the coating compositions of the present invention have good resistance to sterilization, flexibility and substrate adhesion after sterilization, more particularly when the coating compositions of the present invention are applied to metal substrates such as coils and cans. Furthermore, preferred coating compositions of the present invention do not contain additional crosslinkers or crosslinking catalysts, and are BPA-NI (bisphenol a-not intended, also denoted bisphenol a- (NI) or bisphenol a not intended throughout the present specification) and formaldehyde-free.

Examples

The following illustrative examples are meant only to illustrate the invention and are not intended to limit or otherwise define the scope of the invention.

Example 1: synthesis of saturated polyester (A)

A1 liter four-necked round bottom flask equipped with a stirrer, reflux cooler with water separator, nitrogen inlet and thermal sensor was charged with 353g of 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 under a nitrogen sweep ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A mixture of isomeric compounds of decane, which mixture is referred to as TCD-diol, 27g of 1, 4-butanediol, 332g of terephthalic acid, 22g of solvent Nafta 150/180 and 0.6g of monobutyl tin oxide.

The mixture was heated with stirring to 180 ℃ over 90 minutes under a continuous nitrogen flow. The temperature was maintained at 180℃for 30 minutes. The temperature was then raised to 240℃at a heating rate of 10℃per hour and reflux distillation was established by adding the solvent Nafta 150/180 while continuing to separate the reaction water.

Reflux distillation was maintained for about 3 hours until 70g of water distillate was collected and the dynamic viscosity (23 ℃ C.) of the sample diluted to 40% solids with solvent Nafta 150/180 was determined to be 900-1,000mPa.s. The temperature was then reduced to 180℃and the reflux distillation was again adjusted by adding Nafta 150/180 in small portions.

Reflux distillation was continued for about 6 hours until 3.5g of water distillate was collected and the dynamic viscosity (23 ℃ C.) of the sample, having an acid number of less than 4mg KOH/g and diluted to 40% solids with solvent Nafta 150/180, was 3200-3800 Pa.s.

The reaction mixture was cooled down to 145 ℃ and diluted with 150/180 small parts of the solvent Nafta with good stirring, with the aim of a target dynamic viscosity (at 23 ℃) of less than 5000 mpa.s.

The saturated polyester is characterized by a nonvolatile content of 39.9%, measured according to DIN 55671 (foil method), 180℃for 10 min; an acid number of 1.5mg KOH/g, determined according to DIN EN ISO 2114; kinematic viscosity of 4,610mPa.s, determined according to DIN EN ISO 3219 at 23℃and a shear rate of 10.1/s (Anton Paar, physica MCR 1); number average molecular weight and weight average molecular weight of 8,706 g/mol and 34,260g/mol, respectively, as determined by gel permeation chromatography in tetrahydrofuran; the glass transition temperature of 109℃is determined by differential scanning calorimetry in accordance with DIN EN 61006 (method A).

Example 2: synthesis of unsaturated polyester (B)

A1 liter four-necked round bottom flask equipped with a stirrer, reflux cooler with water separator, nitrogen inlet and thermal sensor was charged with 353g of 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 under a nitrogen sweep ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A mixture of isomeric compounds of decane (TCD-diol), 27g of 1, 4-butanediol, 266g of terephthalic acid, 18g of solvent Nafta 150/180 and 0.6g of monobutyl tin oxide.

The mixture was heated with stirring to 180 ℃ over 90 minutes under a continuous nitrogen flow. The temperature was maintained at 180℃for 30 minutes. The temperature was then raised to 240℃at a heating rate of 10℃per hour and reflux distillation was established by adding the solvent Nafta 150/180 while continuing to separate the reaction water.

Reflux distillation was continued for about 5 hours until 58g of water distillate was collected and the acid number was determined to be less than 4mg KOH/g.

The reaction mixture was cooled to 170℃and 39g of maleic anhydride and 0.7g of butylhydroxytoluene were added with stirring.

The temperature was raised to 180℃and reflux distillation was again established by further addition of the solvent Nafta 150/180. Reflux distillation was continued for about 8 hours until 8g of water distillate was collected and the acid number was determined to be less than 4mg KOH/g. The reaction mixture was cooled to 145 ℃ and diluted with a small portion of solvent Nafta 150/180 with good stirring, with the aim of a target dynamic viscosity (at 23 ℃) of less than 5,000 mpa.s.

The unsaturated polyesters are characterized by a nonvolatile content of 44.7%, measured according to DIN 55671 (foil method), 180℃for 10 min; an acid number of 3.4mg KOH/g, determined according to DIN EN ISO 2114; kinematic viscosity of 4,702 Pa.s, measured according to DIN EN ISO 3219, at 23℃and a shear rate of 10.1/s; an intrinsic viscosity of 31.9ml/g, determined in accordance with DIN 51562T1-3 using chloroform as solvent; number average molecular weight and weight average molecular weight of 7,792g/mol and 34,080g/mol, respectively, as determined by gel permeation chromatography in tetrahydrofuran; the glass transition temperature at 105℃is determined by differential scanning calorimetry in accordance with DIN EN 61006 (method A) and an unsaturated equivalent of 1,547g/equivalent.

In examples 2-6, the unsaturated equivalent weight is calculated by dividing the weight of the polyester, which is the sum of the weights of the polyol, polyacid and ethylenically unsaturated diacid minus the weight of water formed during polycondensation, by the number of moles of ethylenically unsaturated diacid present in the initial reaction mixture.

Examples 3 to 5 Synthesis of unsaturated polyesters (B)

The unsaturated polyesters (B) of examples 3, 4 and 5 were prepared according to the method of example 2 (table 1).

In example 3, tetrahydrophthalic anhydride was used instead of maleic anhydride (as correspondingly indicated in table 1) for the further preparation and evaluation of the coating formulation in the absence of the saturated polyester (a) of example 1 as one of the comparative examples shown in table 8 below.

Example 4a in table 1 corresponds to the synthesis of unsaturated polyester (B) using an alternative esterification catalyst (i.e. tetrabutyl titanate was used as esterification catalyst vs in example 4 a. Monobutyl tin oxide was used as esterification catalyst in examples 3-55) and was prepared as follows:

in a 1 liter four-necked round bottom flask equipped with stirrer, reflux cooler with water separator, nitrogen inlet and thermal sensor under nitrogen sweep353g of 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 were charged ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A mixture of isomeric decane compounds (TCD-diol), 27g of 1, 4-butanediol, 232g of terephthalic acid, 18g of solvent naphtha 150/180 and 2.4g of tetrabutyl titanate.

The mixture was heated with stirring to 180 ℃ over a period of 90 minutes under a continuous nitrogen flow. The temperature was maintained at 180℃for 30 minutes. The temperature was then raised to 240 ℃ at a heating rate of 10 ℃/h and reflux distillation was established by adding solvent naphtha 150/180 while continuing to separate the reaction water.

Reflux distillation was continued for about 5 hours until 50g of water distillate was collected and the acid number was determined to be less than 4mg KOH/g.

The reaction mixture was cooled to 140℃and 59g of maleic anhydride and 0.7g of butylhydroxytoluene were added with stirring.

The temperature was raised to 175 ℃ and reflux distillation was again established by further addition of solvent naphtha 150/180. Reflux distillation was continued for 8 hours until 11g of water distillate was collected and the acid value was determined to be less than 4mg KOH/g. The reaction mixture was cooled to 145 ℃ and diluted with solvent naphtha 150/180 more times with good stirring, with the aim of a target dynamic viscosity (at 23 ℃) of less than 5,000 mpa.s.

The unsaturated polyester is characterized by having: a nonvolatile content of 44.7%, determined according to DIN 55671 (foil method), 180℃for 10 min; an acid number of 2.7mg KOH/g, determined according to DIN EN ISO 2114; a kinematic viscosity of 2,509mPa.s, determined according to DIN EN ISO 3219, at 23℃and a shear rate of 10.1/s; an intrinsic viscosity of 28.9ml/g, determined in accordance with DIN 51562T1-3 using chloroform as solvent; number average molecular weight and weight average molecular weight of 7,066g/mol and 28,550g/mol, respectively, as determined by gel permeation chromatography in tetrahydrofuran; glass transition temperature at 105℃as determined by differential scanning calorimetry in accordance with DIN EN 61006 (method A); and 1,017 g/eq unsaturated equivalent.

Example 6: synthesis of unsaturated polyester (B)

The unsaturated polyester (B) of example 6 in table 1 was prepared as follows.

A1 liter four-necked round bottom flask equipped with a stirrer, reflux cooler with water separator, nitrogen inlet and thermal sensor was charged with 176g of 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 under a nitrogen sweep ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]A mixture of isomeric compounds of decane (TCD-diol), 131g of isosorbide, 27g of 1, 4-butanediol, 232g of terephthalic acid, 60g of solvent Nafta 150/180 and 0.6g of monobutyl tin oxide.

The mixture was heated with stirring to 180 ℃ over a period of 90 minutes under a continuous nitrogen flow. The temperature was maintained at 180℃for 30 minutes. The temperature was then raised to 240℃at a heating rate of 10℃per hour and reflux distillation was established by adjusting the amount of solvent Nafta 150/180 while continuing to separate the reaction water.

Reflux distillation was continued at 240 ℃ for 1 hour, thereby forming a bright brown reaction mixture (i.e., no undissolved terephthalic acid was present anymore).

The reaction mixture was cooled to 170℃and 59g of maleic anhydride and 0.7g of butylhydroxytoluene were then added with stirring.

The temperature was raised to 180℃and reflux distillation was again established by adding the solvent Nafta 150/180. Reflux distillation was continued at 180℃for 7 hours and at 200℃for an additional 10 hours, where a total of 61g of reaction water was formed and the acid value was reduced to 1.5mg KOH/g. The reaction mixture was cooled to 120 ℃ and diluted with small portions of methoxypropyl acetate with good stirring, with the aim of a target dynamic viscosity (at 23 ℃) of less than 5,000 mpa.s.

The unsaturated polyester is characterized by having: non-volatile content of 42.0%, measured according to DIN 55671 (foil method), 180℃for 10 min; an acid number of 1.5mg KOH/g, determined according to DIN EN ISO 2114; kinematic viscosity of 2,350mPa.s, determined according to DIN EN ISO 3219, at 23℃and a shear rate of 10.1/s; an intrinsic viscosity of 20.2ml/g, determined in accordance with DIN 51562T1-3 using chloroform as solvent; number average and weight average molecular weights of 2,840g/mol and 20,360g/mol, respectively, as determined by gel permeation chromatography in tetrahydrofuran; glass transition temperature at 96℃as determined by differential scanning calorimetry in accordance with DIN EN 61006 (method A); and 942 g/eq unsaturated equivalent.

TABLE 1

Example 7: coating formulations

A coating formulation was prepared from the unsaturated polyesters (B) of examples 2, 4a, 5 and 6 and the saturated polyester (a) of example 1 in a ratio (calculated as solids) of 25:75 to 50:50 (B: a) and diluted with solvent naphtha 150/180 to a solids content of 40% with stirring; add 0.3% Additol XW 6580 (flow and substrate wetting agent, allnex) and homogenize for several minutes.

For further details of the individual coating formulations prepared, see tables 2-7 and tables 8-9 below.

Example 8: coating application and evaluation

The 40% solids coating formulation was bar coated onto tin plated steel plates at a wet film thickness of 40 μm. After a flash time of 5 minutes, the coated plate was oven dried at 200℃for 12min, giving a dry film thickness of 10+/-2. Mu.m.

And (3) testing: the evaluation of the coating of each coating formulation prepared and applied to the panel was based on the following test.

The transverse cut test was employed to test the adhesion of dry coatings on their substrates by means of a series of cuts through the coating, according to DIN EN ISO 2409. The two series of parallel cuts intersect each other at an angle to obtain 25 or 100 similar square patterns. After a short treatment with a hard brush or an adhesive tape for a hard substrate, the area of the grid (ground area) was evaluated by using a table chart. Classified as from 0 to 5, where 0 corresponds to the case where the edges of the cuts are perfectly smooth, and where the squares without the grid are separated.

Visual assessment of the surface, flow, leveling and defects of the coating and classification into five grades from best (0) to worst (5).

The degree of "curing" or crosslinking is determined as acetone resistance. This test was performed as described in ASTM D5402. Double rub numbers (i.e., the number of movements back and forth until the metal substrate becomes visible) are reported. Preferably, the acetone solvent resistance is at least 30 double rubs.

-performing an impact test according to ASTM 2794; the coating was evaluated at 32 ft-lbs. impact. Damage to the coating can be determined visually or with low power magnification. The organic coating to be tested was applied to four or more suitable thin metal plates. After curing of the coating, it was stored at 20 ℃ for 1 hour, after which the standard weight was allowed to fall from standard height to deform the coating and the substrate. The indentation is either intrusion (direct impact; on the coating side) or extrusion (reverse impact; on the metal side).

Wedge bend testing was performed according to ASTM D3281 using an Erichsen Folded-Impact test apparatus, model 471, taper bolt 5mm diameter. The test wedge was formed from a coated rectangular metal test sheet (measuring 10cm length x2cm width). The test wedge was formed from a coated sheet by folding (i.e. bending) the sheet around a 5mm diameter mandrel. To accomplish this, the mandrel is placed on the coated sheet such that it is oriented parallel to and equidistant from the length edges of the sheet. The resulting test wedge had a wedge diameter of 5mm and a length of 100 mm. To evaluate the wedge-bending properties of the coating, the test wedge was placed longitudinally in the metal block of the wedge-bending tester and a 1,800+/-g weight was dropped from a height of 50cm onto the test wedge. The deformed test wedge was then immersed in the acidic copper sulfate test solution for 5 minutes. By mixing 132g of CuSO ₄ ·5H ₂ The solution was prepared by dissolving O in 900g of water containing 20g of concentrated hydrochloric acid. The plates were removed from the solution, rinsed with tap water, wiped dry, examined under a microscope, and the number of millimeters of coating defects along the deformation axis of the test wedge was determined. The data are expressed as percent wedge bend using the following calculations: 100% × [ (wedge length 100 mm) - (defect mm)]/(wedge length 100 mm). If the coating exhibits a percent wedge bend of 70% or greater, it is considered to satisfy the wedge bend test.

-deep drawing test-Erichsen cupping test according to DIN EN 1669, wherein a metal substrate comprising a coating is shaped into a cup. In this test, a metal substrate was placed on the die surface and drawn into a cup by means of a stretch-punch. An asymmetry is formed with four different angles, called a "tetragonal box" (40 x 40 mm), where the first radius is largest and the fourth radius is smallest. The shaping is done by a single stretching step with a stretching force of 10kN and a sheet clamping force of 5 kN. The total height of the tank was 25mm. Visual inspection of defects on the top and sides of the coated surface was performed after the stretching process and the percentage of damage to the sides was calculated relative to the 25mm total height. "0%" means that no damage is observed and the coating on the side can still (OK) over its entire side height, however the damage percentage is given by "(Y/25). Times.100%" where Y mm is the height up to the side where damage is observed.

Blush resistance measures the ability of a coating to withstand various solutions. When the film absorbs the solution, it typically becomes cloudy or appears white. Blushing was visually determined using a scale of 0 to 5, where a scale of "0" indicates no blushing and a scale of "5" indicates severe whitening of the film.

For further details on the preparation of the various coating formulations and corresponding evaluation results, see tables 2-9 below.

Examples 9-25 coating formulations and evaluation

Coating formulations containing 75wt% of the saturated polyester of example 1 and 25wt% of the unsaturated polyester of example 2 or 5, respectively, were prepared (table 2). The metal catalysts used in examples 9 and 11 wereIron (Borchers GmbH).

TABLE 2

The cured coatings of examples 9-14 were subjected to sterilization in deionized water at a temperature of 129 ℃ for 1 hour after being subjected to the deep drawing test (table 3).

TABLE 3 Table 3

The cured coatings of examples 9-14 were subjected to sterilization in a 2wt% lactic acid solution at a temperature of 129 ℃ for 1 hour after being subjected to the deep drawing test (table 4).

TABLE 4 Table 4

The coatings of examples 9-14 were applied and cured on flat metal substrates and evaluated for flow, blushing and adhesion (table 5).

TABLE 5

	Example 9	Example 10	Example 11	Example 12	Example 13	Example 14
							Flow of	Difficulty and difficulty in	Difficulty and difficulty in	Can be used for	Can be used for	Can be used for	Can be used for
Whitening of	1	2	1	1	1	2
							Transverse cutting	1	0	5	5	4	3

The coatings of examples 9-14 applied and cured on flat surfaces were subjected to sterilization in 0.05wt% cysteine solution at a temperature of 121 ℃ for 90 minutes and evaluated for flow, whitening and adhesion. By adding 0.5g of cysteine to a solution consisting of 3.56g KH ₂ PO ₄ And 7.22g Na ₂ HPO ₄ The cysteine solution was prepared in 1 liter of the prepared phosphate buffer solution (table 6).

TABLE 6

	Example 9	Example 10	Example 11	Example 12	Example 13	Example 14
							Flow of	Can be used for	Can be used for	Can be used for	Can be used for	Can be used for	Can be used for
Whitening of	2	1	1	3	2	3
							Transverse cutting	0	0	4	2	5	4

Table 7 shows coating formulations comprising different ratios of the saturated polyester (a) of example 1 and the unsaturated polyesters (B) of examples 2 and 5, respectively. In the same table, coating evaluations are reported.

TABLE 7

Table 7 (subsequent)

In table 8, coating formulations comprising unsaturated polyesters (B) of examples 2, 3 and 4, respectively, in the absence of saturated polyester (a) of example 1 (examples 19, 20 and 21, respectively) are shown.

In the same table are shown coating formulations comprising unsaturated polyester (B) of example 4 and saturated polyester (a) of example 1 in different ratios (examples 22 and 23, respectively).

Also shown in table 8 is a coating formulation (=example 22 a) comprising the unsaturated polyester (B) of example 4a and the saturated polyester (a) of example 1.

Further, in table 8, example 22B in which tetrabutyl titanate was post-added to a paint formulation as an adhesion promoter is shown as compared with example 22a in which tetrabutyl titanate was added as an esterification catalyst in the synthesis of unsaturated polyester (B). In example 22B, monobutyl tin oxide was used as an esterification catalyst in the synthesis of unsaturated polyester (B).

In the same table, coating evaluations are reported. The coating formulations of examples 19-21 are comparative examples. The metal catalyst used in example 20 wasIron (Borchers GmbH).

TABLE 8

* Iron 2-ethylhexanoate (OCTA)Iron 7/8) Table 8 (continuous)

Table 8 (subsequent)

Table 8 (subsequent)

Table 8 (subsequent)

A comparison of example 18 comprising a blend of saturated polyester (a) and unsaturated polyester (B) and example 19 comprising only unsaturated polyester (B) of example 2 clearly shows that the coating properties by using a coating formulation comprising a blend of one or more (a) and one or more (B) have an advantageous synergistic effect. It is noted that the binders of example 18 and comparative example 19 have the same amount of ethylenically unsaturated bonds.

In table 9, a coating formulation comprising: saturated polyester of example 1 (=example 24); or (b)VPE 6104/60MPAC, a saturated polyester from Allnex (=example 25); each is ANDPR 521/60B (a phenolic resin from Allnex) in the form of a mixture, wherein +.>XK 406N is an acidic catalyst from Allnex based on phosphoric acid derivatives. The coating composition was formulated at 40% solids content and corresponds to a formaldehyde-containing basis. In the same table, coating evaluations are reported.

TABLE 9

Watch 9 (subsequent)

The above examples of the coating formulation of the present invention (examples 9-18 and examples 22, 22a, 22b and 23) clearly exhibited performance combinations equal to or better than the prior art products on the market (examples 24 and 25, which are benchmark coating formulations) and better than comparative examples 19-21.

In example 22a, butyl titanate was used as the esterification catalyst for the synthesis of the unsaturated polyester of example 4a (as an alternative to monobutyl tin oxide used as the esterification catalyst for the synthesis of the unsaturated polyester of example 4, wherein example 4 was used in the formulations of examples 22 and 22 b). The results indicate that butyl titanate can be used as an esterification catalyst for polyester formation as a substitute for tin derivatives.

Furthermore, the presence of butyl titanate in the coating formulation from the polyester esterification catalyst (example 22 a) or added to the coating formulation at the time of its preparation (example 22 b) resulted in an overall improvement of the coating properties. In particular, when butyl titanate is added to the coating formulation at the time of its preparation (example 22 b), a significant improvement in coating properties (i.e. resulting in improved bactericidal properties of the coating without compromising other properties of the coating) is observed after the bactericidal test.

Claims (24)

1. A coating composition comprising a blend of polyesters,

wherein the blend comprises 0.1 to 99.9wt% of one or more saturated polyesters (a), and 99.9 to 0.1wt% of one or more unsaturated polyesters (B), based on the total weight of polyesters (a) and (B);

wherein the one or more saturated polyesters (a) and the one or more unsaturated polyesters (B) have: a weight average molecular weight Mw of at least 15,000g/mol, determined by gel permeation chromatography using tetrahydrofuran as solvent; and a glass transition temperature of at least 60 ℃ as determined by differential scanning calorimetry according to DIN EN 61006 method a.

2. The coating composition of claim 1, wherein the one or more saturated polyesters (a) and/or one or more unsaturated polyesters (B) comprise one or more aliphatic cyclic groups.

3. The coating composition according to claim 1 or 2, wherein the one or more saturated polyesters (a) and/or one or more unsaturated polyesters (B) comprise aliphatic polycyclic groups.

4. A coating composition according to any one of claims 1-3, wherein the one or more saturated polyesters (a) and one or more unsaturated polyesters (B) have a weight average molecular weight Mw of 20,000-50,000g/mol and/or a glass transition temperature of 80-120 ℃.

5. The coating composition of any one of claims 1-4, wherein the one or more unsaturated polyesters (B) are the reaction product of:

an acid component comprising 50 to 90 mole% terephthalic acid and/or isophthalic acid, 10 to 50 mole% of one or more unsaturated dibasic acids or anhydrides thereof, and 0 to 30 mole% of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or anhydrides thereof; and

a glycol component comprising 5 to 30 mole% of one or more aliphatic and/or cycloaliphatic diols, and 70 to 95 mole% of one or more aliphatic polycyclic diols; and/or

Wherein the one or more saturated polyesters (a) are the reaction product of:

An acid component comprising 50 to 100 mole% terephthalic acid and/or isophthalic acid, and 0 to 50 mole% of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or anhydrides thereof; and

a glycol component comprising 5 to 30 mole% of one or more aliphatic and/or cycloaliphatic diols, and 70 to 95 mole% of one or more aliphatic polycyclic diols.

6. The coating composition of claim 5, wherein the one or more aliphatic polycyclic diols in the one or more saturated polyesters (a) and/or the one or more unsaturated polyesters (B) comprise a diol selected from the group consisting of bicyclic diols, tricyclic diols, and mixtures thereof.

7. The coating composition of any of claims 5-6, wherein the one or more aliphatic polycyclic diols of the one or more saturated polyesters (a) and/or the one or more unsaturated polyesters (B) comprise heterobicyclic diols having a bicyclic aliphatic ring wherein one or more hydrocarbons in the ring are replaced with heteroatoms and the heterobicyclic diols are selected from isosorbide, isomannide, isoidide, and derivatives thereof.

8. The coating composition of any one of claims 5-6, wherein the one or more saturated polyesters (a) and/or one or more aliphatic polycyclic diols of the one or more unsaturated polyesters (B) comprise a tricyclic diol selected from the group consisting of: 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 5, 8-bis (hydroxymethyl)Base) -tricyclo [5.2.1.0 ^2,6 ]Decane, and mixtures thereof.

9. The coating composition of any one of claims 5-8, wherein the one or more unsaturated dibasic acids or anhydrides thereof in the one or more unsaturated polyesters (B) are selected from the group consisting of alpha, beta-unsaturated dicarboxylic acids, alpha, beta-unsaturated anhydrides, unsaturated dibasic acids comprising a separate ethylenically unsaturated double bond, unsaturated anhydrides comprising a separate ethylenically unsaturated double bond, and mixtures thereof.

10. The coating composition of any one of claims 5-9, wherein the one or more unsaturated dibasic acids or anhydrides thereof in the one or more unsaturated polyesters (B) are selected from maleic acid, fumaric acid, itaconic acid, mesaconic acid, citraconic acid, tetrahydrophthalic acid, nadic acid, methylnadic acid, or anhydrides thereof, and mixtures thereof.

11. The coating composition of any one of claims 1-10, wherein the one or more unsaturated polyesters (B) have an unsaturated equivalent weight of 300-6,000 g/equivalent.

12. The coating composition according to any one of claims 1-11, wherein the one or more saturated polyesters (a) are terephthalic acid, 1, 4-butanediol and 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Reaction product of a mixture of decanes.

13. The coating composition according to any one of claims 1-12, wherein the one or more unsaturated polyesters (B) are terephthalic acid, maleic anhydride and/or fumaric acid, 1, 4-butanediol and 3, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane, 4, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Decane and 5, 8-bis (hydroxymethyl) -tricyclo [5.2.1.0 ^2,6 ]Mixing of decaneReaction products of the materials.

14. The coating composition according to any one of claims 1 to 13, comprising 35 to 50wt% of a blend comprising one or more saturated polyesters (a) and one or more unsaturated polyesters (B), and 50 to 65wt% of one or more organic solvents selected from the group consisting of: aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, glycols, glycol ethers, glycol esters, and mixtures thereof.

15. The coating composition according to any one of claims 1-14, comprising one or more additives selected from the group consisting of: carriers, additional polymers, emulsifiers, pigments, metal powders or pastes, fillers, anti-migration aids, biocides, extenders, lubricants, coalescing agents, wetting agents, biocides, plasticizers, crosslinking agents, crosslinking catalysts, defoamers, colorants, waxes, antioxidants, corrosion inhibitors, flow control agents, thixotropic agents, dispersants, adhesion promoters, UV stabilizers and scavengers.

16. The coating composition of any one of claims 1-15 comprising 0.05 to 1.5wt% adhesion promoter, based on the weight of non-volatile materials in the coating composition.

17. The coating composition of any one of claims 1-16, comprising 0.05-1.5wt% of a tetraalkyl titanate, preferably a tetrabutyl titanate, based on the weight of non-volatile materials in the coating composition.

18. The coating composition of any one of claims 1-17 comprising less than 10,000ppm of an ingredient selected from the group consisting of: bisphenol-a is not intended, formaldehyde, isocyanate, or mixtures thereof.

19. An unsaturated polyester (B) which is the reaction product of:

an acid component comprising 50 to 90 mole% terephthalic acid and/or isophthalic acid, 10 to 50 mole% of one or more unsaturated dibasic acids or anhydrides thereof, and 0 to 30 mole% of one or more saturated aliphatic, saturated cycloaliphatic or aromatic dibasic acids or anhydrides thereof; and

a glycol component comprising 5 to 30 mole% of one or more aliphatic and/or one or more cycloaliphatic diols, and 70 to 95 mole% of one or more aliphatic polycyclic diols,

and has:

A weight average molecular weight of at least 15,000g/mol, determined by gel permeation chromatography using tetrahydrofuran as solvent,

a glass transition temperature of at least 60℃as determined by differential scanning calorimetry according to DIN EN 61006 method A, and

300-6,000 g/eq unsaturated equivalent.

20. A substrate coated with the coating composition of any one of claims 1-18, wherein the substrate is selected from the group consisting of metal, glass, polymer, composite, concrete, ceramic and engineered wood, preferably a metal substrate.

21. The substrate according to claim 20, wherein the metal substrate is a metal foil or can, preferably a can for food and beverage applications.

22. A method of producing a coated metal substrate comprising the steps of:

applying the coating composition of any one of claims 1-18 to at least one side of a metal substrate optionally pretreated and/or comprising a primer, at a coating thickness adjusted to obtain a dry coating thickness of less than 60 μm;

the applied coating composition is baked at a temperature of at least 150 ℃ for a period of at least 20 seconds to form a metal substrate coated with the crosslinked coating.

23. A method of making a coated can body and can end comprising the steps of:

Cutting the coated metal substrate of claim 22 into metal pieces of a desired size and shape to form a can body and can end ready for assembly; or alternatively

Cutting the coated metal substrate of claim 22 into metal pieces of a desired size and shape, stamping the metal pieces into cans, and cutting the can ends into a desired shape in preparation for assembly.

24. Use of the coating composition of any one of claims 1-18 for coating a metal substrate.