DD253253A1 - OUTSTANDING PAINTED PAINT - Google Patents

Abstract

The invention relates to an oven-drying base paint with improved properties under the conditions of a continuous heat load for the application in the dipping process. The object of the invention is to provide by using a special combination of binders an oven-drying base color whose initially good mechanical properties are maintained even after Dauerwaermbelastung and have the application in the dipping process on improved rheological properties. According to the invention, the binder combination consists of 30 to 40% by weight of an oil- or fatty acid-modified alkyd resin having a fatty acid content of 36 to 42% by weight, 10 to 15% by weight of an etherified, medium-reactive melamine-formaldehyde resin, 20 to 30% by weight .-% of a low molecular weight esterification product of formula (I), wherein the radical R is a diol specifically esterified with fatty acid and n is at most 1.5, and 20 to 30 Ma .-% of a low molecular weight esterification product according to the formula (I), wherein the radical R is a diol and n is 1.5 to 2.0. Formula (I)

Description

between 36 and 42% by mass,

an etherified medium reactive melamine-formaldehyde resin,

a low molecular weight esterification product of the formula (I),

R-O-CO-CH = CH-CO-O

30bis40Ma .-%

10 to 15Ma .-% _ 20 to 30Ma .-%

wherein the radical R is a partially esterified with fatty acid diol and η is at most 1.5, and 20 to 30 wt .-% of a low molecular weight esterification product of the formula (I), wherein

the radical R is a diol and η is 1.5 to 2.0 is used.

Field of application of the invention

The invention relates to an oven-drying base paint with improved properties under the conditions of a continuous heat load for the application in the dipping process.

State of the art

The use of alkyd-melamine resin combinations for oven-drying paints, including base paints, is well known. For such binder combinations short to medium oil alkyd resins are used with a content of 30 to about 50% of drying, semi-drying or non-drying fatty acids.

Depending on the fatty acid content and the nature of the polyol components, different property images are obtained, especially in primary colors. When using short-oil alkyd resins with a fatty acid content of up to 40% (see DD-PS 121126) basic colors are obtained, which quickly degrade the initial good mechanical properties with continuous heat load and at the same time lead to a very different layer thickness distribution when used in the dipping process.

An improvement in the mechanical properties of the oven-drying primary colors is achieved by the use of medium-oil alkyd resins. The disadvantage remains in this case but the different coating thickness distribution when applying the base color in the dipping process and the insufficient initial hardness. This is quality-reducing for many applications.

Object of the invention

The aim of the invention is to provide an oven-drying base color, which is improved simultaneously, especially when used in the dipping process in several important application properties.

Essence of the invention

The invention has for its object to provide by using a special combination of binders an oven-drying base color, the initially good mechanical properties are maintained even after long-term heat load and have the application in the dipping process on improved theological properties. According to the invention, the binder combination contains

-30 to 40% by weight of an oil or fatty acid-modified alkyd resin having a fatty acid content of between 36 and

42% by mass,

From 10 to 15% by mass of an etherified melamine-formaldehyde medium reactive resin,

20 to 30% by mass of a low molecular weight esterification product of the formula (I),

O-CO-CH = CH-CO-O

wherein the radical R is a partially esterified with fatty acid diol and η is at most 1.5,

and -20 to 30 wt .-% of a low molecular weight esterification product of the formula (I), wherein the radical R a

Diol is and η is 1.5 to 2.0.

As the oil or fatty acid-modified alkyd resin, there is used a resin crosslinkable with aminoplast resin which has a fatty acid content of 36 to 42 mass%.

The melamine-formaldehyde resin used are those known resins which have been etherified with primary alcohols, preferably n-butanol.

The dicyclopentadiene-modified polyesters of the formula (I) are prepared by known processes. Component of the radical R are diols, preferably aliphatic diols up to a maximum of 8 carbon atoms.

In the case of the third component, the diol is partially esterified with fatty acid. The fatty acid used is non-, semi- or drying fatty acids, the fatty acid content preferably being 15 to 30% and η being a value of from 1 to 1.5.

For the fourth component, compliance with the range of 1.5 to 2.0 is absolutely necessary for the value η. The novel oven-drying base color can be produced using pigments, fillers, solvents and, if appropriate, paint auxiliaries according to customary production technologies and has the usual pigmentation level for primers.

The processing of this base color can be carried out by all known methods, for example brushing, spraying, rolling, flooding and dipping, the advantages of the base color according to the invention becoming particularly clear in the dipping process. The thermal drying of the base color is carried out by conventional methods at temperatures from 353 K. Compared to the known prior art, the base color according to the invention shows significant advantages. It has very good mechanical properties, which are expressed in corresponding values of pendulum hardness, mandrel bending test, Erichsen depression and cross-hatch, which remain virtually unchanged even after long-term heat stress. These properties are particularly important in the coating of metallic articles subject to continuous heat load, such as e.g. Radiator. In addition, the favorable theological behavior achieves a uniform layer thickness distribution in the dip coating even of large-area objects.

embodiments

The preparation of the invention and the comparative base colors was carried out according to a uniform formulation with a pigment-binder ratio of 1.5: 1.

The pigment mixture consists of 50% by weight of fillers, talc and kaolin in the ratio of about 1: 1, and 50% by weight of pigments, TiCVAnatas and lithopone in a ratio of 2: 1. The processing viscosity was adjusted with a known solvent mixture to 28 seconds expiration. The application was carried out on glass or metal sheets of various dimensions by immersion.

The staining of the base color took place at 393 K for 30 minutes.

The evaluation of the technical parameters took place 2 hours after firing and after a heat load of 353K over a period of 14 days.

In the following examples, the binder combinations used are described, wherein the mass data refer to undissolved constituents.

Example 1:

36% by weight of a phthalate resin modified with 39% by weight of tall oil fatty acid with a polyol mixture

Pentaerythritol and trimethylolpropane, 12% by weight of a medium reactive melamine resin etherified for 393 K of normal n-butanol,

24% by weight of a low molecular weight esterification product which consists of 61% by weight of hydroxy-dicyclopentene-maleic anhydride

most acidic, 24% by weight tallol fatty acid and 15% by weight 1,3-butanediol,

28% by weight of a low molecular weight esterification product prepared from 82% by weight of hydroxy-dicyclopentene-maleic acid half ester and 18% by weight of 1,3-butanediol.

Example 2:

(Comparison according to DD-PS 121126)

75% by mass of a phthalate resin modified with 39% by weight of tallol fatty acid with a polyol mixture of pentaerythritol and trimethylolpropane,

25% by weight of a medium-reactive melamine resin which is etherified with n-butanol for 393 K.

Example 3:

(Comparison)

67% by weight of a glycerol-esterified phthalate resin modified with 49% by weight of ricinene fatty acid and 33% by mass of a medium-reactive melamine resin etherified with n-butanol for 393 K.

The test results obtained are shown in the following table:

table

exam

example 1 Example 2 Example 3

Pendulum hardness (s) acc. To TQL 29771 after firing after heat load grooving (mm) after TGL14301 / 03 after firing after heat load cross cut (KW) after TGL14302 / 05 after firing after heat load mandrel bending test (mm) after TG L14302 / 02 after Burn-in after heat load Coating thickness (microns) at the centimeter 0 at the centimeter 50 at the centimeter 100 Impact depression (cm) afterGL25615 after firing after the heat load

80 105

6.3 5.0

<5 <5

28 30 33

60 50

4.0 1.0

60 100

6.0 4.6

<5 5

18 28 40

55 35

Claims (1)

Invention claim: Oven-drying base color, particularly suitable for application by the dipping method, based on crosslinkable binders, aminoplast resins, pigments, fillers, solvents and optionally paint auxiliaries, characterized in that a combination of an oil or fatty acid modified alkyd resin having a fatty acid content