CN104119794A - Aqueous coating for foodstuff packaging - Google Patents

Abstract

An aqueous coating for foodstuff packaging is an aqueous coating composition comprising the following compositions: A) at least one kind of polyisocyanates, wherein each molecule of the polyisocyanate averagely at least comprises two NCO groups, and at least 85% of NCO groups are blocked by an end-capping reagent, and the end-capping reagent is piperidone; B) at least one kind of hydrophilic polyester polyols of which each molecule comprises at least two active hydroxyl groups, or a mixture of hydrophilic and non-hydrophilic polyester polyols, wherein the acid value of the composition B) is not less than 35 mg KOH/g, the hydroxyl value is 10 mg KOH/g to 500 mg KOH/g, and the weight-average molecular weight MW is larger than 2000 g/mol; and C, an optional additive. The coating composition is applicable to coat a package material, and is especially applicable to the inner side of a coated tank.

Description

A kind of water-borne coatings for food product pack

Technical field

The present invention relates to water-borne coatings, be specially a kind of water-borne coatings for food product pack.

Background technology

At present, mainly contain the mono-component polyurethane baking vanish (1K PU baking vanish) of blocked polyisocyanates linking agent component and polyvalent alcohol binder ingredients and be known in the application of the coating of automotive OEM finish, conventional industrial coating and coil coating.1KPU baking vanish is can solidify to form the coating composition of the netted structure of urethane when temperature raises.In curing process, (solution) end-blocking NCO radical reaction of the light base in polyvalent alcohol and polyisocyanates.On the contrary, with the NCO group of CH-acid ester end-blocking, carry out with reacting by transesterification reaction of polyvalent alcohol, wherein do not produce the netted structure of urethane; As a result, the coating composition based on these blocked polyisocyanates is not called 1K PU baking vanish.

The shortcoming of using blocked polyisocyanates to produce polyurethane coating is, depends on the character of end-capping reagent and the condition of baking, more or less has some end-capping reagents to remain in coating with the form of dissociating.Remaining end-capping reagent content depends on activity and the baking condition of specific end-capping reagent itself, end-capping reagent.

Prepare metal packing material coating as the process of can coating in, by tinplate or the made tinsel of aluminium, for example with baking vanish, applied, after varnish solidifies, be processed into required goods.For this type coating, there is strict requirement, especially for food product containers during as the undercoat of beverages can.This coating must be enough pliable and tough, can in the process of producing container and Transport Package article, bear certain distortion, and that coating does not have is destroyed, and in addition, metal base must obtain safe and reliable protection, is not subject to the impact of corrosive medium on it.In distortion and sterilization process subsequently, the ability bonding with metal base all must exist, because this is especially essential for the container as food and drink packing.Produce and later storage process in, coating ingredients enters

It is disadvantageous entering in wrap food, because this can cause the destruction to quality product.

The application of the coating composition based on diglycidyl rthers of bisphenol-A (BADGE) is known.Also know, this substance that shows mutagenic activity in a small amount of test in vitro enters into wrap food.Therefore, target is to use the coating that does not contain BADGE as the tank undercoat with Food Contact.

The application of polyurethane powder coating composition based on polyisocyanates and polyvalent alcohol in Production and Packaging container undercoat is described in DE-A 19545424.The major portion of using polyurethane coating composition based on blocked polyisocyanates to apply the food product containers of long-term and Food Contact is unknown.This is because known this type of coating comprises a certain amount of residual free end-capping reagent.It is contemplated that, these chemicals will enter into contents, and can cause changing odor or make food muddy, top it all off, infringement human consumer's health.

Therefore, never considered to apply with discharging coating composition end-capping reagent, based on blocked polyisocyanates in cross-linking process the surface directly contacting with food, because the release of end-capping reagent exists potential toxicology risk.Especially, up to now also without any attempting the water-based paint compositions based on urethane as this object.

Summary of the invention

Technical problem solved by the invention is to provide a kind of water-borne coatings for food product pack, to solve the shortcoming in above-mentioned background technology.

Technical problem solved by the invention realizes by the following technical solutions:

For a water-borne coatings for food product pack, comprise the water-based paint compositions of following component:

A) at least one polyisocyanates, on average at least contains 2 NCO groups in each molecule of described polyisocyanates, and at least 85% NCO group end-capping reagent end-blocking wherein, and described end-capping reagent is penta interior phthalein amine;

B) at least one each molecule, on average at least contain the hydrophilic polyester polyvalent alcohol of 2 light base groups of activity, or the mixture of wetting ability and non-hydrophilic polyester polyvalent alcohol, B component wherein) acid number is not less than 35 milligrams of KOH/ gram, hydroxyl value is 10 milligrams of KOH/ gram to 500 milligrams KOH/ gram, weight-average molecular weight M _w2000 grams/mol of >;

C) optional additive;

Wherein, blocked isocyanate groups and B component component A)) isocyanic ester-active group between equivalence ratio be 0.1:1 to 10.0:1.

In the present invention, described component A) comprising:

I) polyisocyanates of 100 equivalent %, wherein I) in the NCO group of at least 85 equivalent % by interior penta interior phthalein amine end-blocking;

II) optional additive.

In the present invention, described polyester polyol B) comprise a) and b), c), d), e) product that reacts, wherein:

A) be the carboxyl acid component of 40 % by mole to 49 % by mole, it comprises:

A1) aliphatic series, alicyclic, the araliphatic of one or more COOH functionality > 2;

A2) optional aromatics, alicyclic and/or aliphatic monocarboxylic acid;

B) be the alkoxide component of 51 % by mole to 60 % by mole, it comprises:

B1) one or more number-average molecular weights are that 62 grams/mol to 272 grams/mol and average OH functionality are greater than 2 aliphatic series, alicyclic and/or araliphatic polyvalent alcohol;

B2) optional aliphatic series, alicyclic and/or araliphatic monohydroxy-alcohol;

C) be optional water;

D) be neutralizing agent;

E) be optional solvent and additive.

beneficial effect

Coating composition of the present invention is applicable to apply wrapping material, is particularly useful for applying the inner side of tank.They also can be used to apply the outside of tank.Drawing materials of wrapping material is very wide, and can have a variety of shapes.Preferred material comprises blackplate, tinplate and various iron alloy, if their coated one deck passivation layers based on nickel compound, chromium cpd and zn cpds of suitable words.

Embodiment

For technique means, creation characteristic that the present invention is realized, reach object and effect is easy to understand, below in conjunction with specific embodiment, further set forth the present invention.

embodiment 1

A kind of water-borne coatings for food product pack, the water-based paint compositions that comprises following component: two kinds of polyisocyanates, in each molecule of polyisocyanates, on average contain 4 NCO groups, and 95% NCO group end-capping reagent end-blocking wherein, described end-capping reagent is penta interior phthalein amine; In three kinds of each molecules, on average contain the hydrophilic polyester polyvalent alcohol of 5 light base groups of activity, or the mixture of wetting ability and non-hydrophilic polyester polyvalent alcohol, wherein B component) acid number be 45 milligrams of KOH/ gram, hydroxyl value is 100 milligrams of KOH/ gram, weight-average molecular weight M _w=3000 grams/mol; Optional additive; Wherein, blocked isocyanate groups and B component component A)) isocyanic ester-active group between equivalence ratio be 0.1:1 to 10.0:1.Described component A) comprising: I) polyisocyanates of 100 equivalent %, wherein I) in the NCO group of at least 85 equivalent % by interior penta interior phthalein amine end-blocking; II) optional additive.Described polyester polyol B) comprise a) and b), c), d), e) product that reacts, wherein: a) be the carboxyl acid component of 40 % by mole to 49 % by mole, it comprises: a1) aliphatic series, alicyclic, the araliphatic of one or more COOH functionality > 2; A2) optional aromatics, alicyclic and/or aliphatic monocarboxylic acid; B) be the alkoxide component of 51 % by mole to 60 % by mole, it comprises: b1) one or more number-average molecular weights are that 62 grams/mol to 272 grams/mol and average OH functionality are greater than 2 aliphatic series, alicyclic and/or araliphatic polyvalent alcohol; B2) optional aliphatic series, alicyclic and/or araliphatic monohydroxy-alcohol; C) be optional water; D) be neutralizing agent; E) be optional solvent and additive.

More than show and described ultimate principle of the present invention and principal character and advantage of the present invention; the technician of the industry should understand; the present invention is not restricted to the described embodiments; that in above-described embodiment and specification sheets, describes just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications; these changes and improvements all fall in the claimed scope of the invention, and the claimed scope of the present invention is defined by appending claims and equivalent thereof.

Claims (3)

1. for a water-borne coatings for food product pack, it is characterized in that, comprise the water-based paint compositions of following component:

A) at least one polyisocyanates, on average at least contains 2 NCO groups in each molecule of described polyisocyanates, and at least 85% NCO group end-capping reagent end-blocking wherein, and described end-capping reagent is penta interior phthalein amine;

B) at least one each molecule, on average at least contain the hydrophilic polyester polyvalent alcohol of 2 light base groups of activity, or the mixture of wetting ability and non-hydrophilic polyester polyvalent alcohol, B component wherein) acid number is not less than 35 milligrams of KOH/ gram, hydroxyl value is 10 milligrams of KOH/ gram to 500 milligrams KOH/ gram, weight-average molecular weight M _w2000 grams/mol of >;

C) optional additive;

Wherein, blocked isocyanate groups and B component component A)) isocyanic ester-active group between equivalence ratio be 0.1:1 to 10.0:1.

2. a kind of water-borne coatings for food product pack according to claim 1, is characterized in that described component A) comprising:

I) polyisocyanates of 100 equivalent %, wherein I) in the NCO group of at least 85 equivalent % by interior penta interior phthalein amine end-blocking;

II) optional additive.

3. a kind of water-borne coatings for food product pack according to claim 1, is characterized in that, described polyester polyol B) comprise a) and b), c), d), e) product that reacts, wherein:

A) be the carboxyl acid component of 40 % by mole to 49 % by mole, it comprises:

A1) aliphatic series, alicyclic, the araliphatic of one or more COOH functionality > 2;

A2) optional aromatics, alicyclic and/or aliphatic monocarboxylic acid;

B) be the alkoxide component of 51 % by mole to 60 % by mole, it comprises:

B1) one or more number-average molecular weights are that 62 grams/mol to 272 grams/mol and average OH functionality are greater than 2 aliphatic series, alicyclic and/or araliphatic polyvalent alcohol;

B2) optional aliphatic series, alicyclic and/or araliphatic monohydroxy-alcohol;

C) be optional water;

D) be neutralizing agent;

E) be optional solvent and additive.