DE2423889C3 - Thermosetting, powdery coating agent - Google Patents

Description

R R '

I I

CH = CR ₁₁ -CH

CH ₁

wherein R and R 'denote the radical —H or —CH, mean and R "the group

—C — O — CH, -

35

40

e) 24 to 42 percent by weight styrene or vinyltop

luol are built up as well

(B) 6 to 16 weight percent of at least one dicarboxylic acid anhydride having melting points of from about 60 to 140 ⁰ C, (C) 0.5 to 1.8 percent by weight N, N'-bis- (Dimethylaminoisobutyliden) melamine, and (D) the flow regulating means and other common additives

2. Coating agent according to claim 1, characterized in that component (A) consists of one Copolymers made up of:

a) 12 to 16 percent by weight glycidyl methacrylate,

b) 14 to 18 percent by weight of hydroxyethyl methacrylate,

c) 24 to 38 percent by weight of ethyl acrylate,

d) 6 to 14 percent by weight methyl methacrylate and

e) 30 to 42 percent by weight styrene
consists

3. Coating agent according to claim 1, characterized in that component (A) consists of one Copolymer made up of:

a) 12 to 18 percent by weight glycidyl methacrylate

b) 4 to 8 percent by weight of hydroxyethyl methacrylate

c) 24 to 28 percent by weight of n-butyl acrylate,

d) 6 to 14 percent by weight methyl methacrylate and

e) 38 to 42 percent by weight styrene
consists

4. for manufacturing the cited in claim 1. powdery coating agent, dadu ^r ch in that this is prepared by mixing, homogenizing fusion and grinding the components required method.

5. Use of the powdery coating agent according to one of claims 1 to 3 for Production of coatings that are baked for 15 to 30 minutes at 150 to 180 ° C.

or

-CH ₁ -O-CH, -

or

-CH ₂ -OC-CH = CH-CO-CH ₂ -

Il Il

ο ο

or

- CH, -O-C

CO-CH ₂ -

represents and where π means the value 1 or zero,

b) 4 to 20 percent by weight of hydroxyalkyl esters of acrylic or methacrylic acid, the Hydroxyalkyl ester group is saturated and contains 2 to 4 carbon atoms,

c) 24 to 38 percent by weight of acrylic acid esters of aliphatic saturated monoalcohols with 1 up to 8 carbon atoms,

d) 6 to 14 percent by weight methacrylic acid esters of aliphatic saturated monoalcohols with 1 to 8 carbon atoms and

45 The invention relates to thermosetting powdery

Coating agents, often also called powder coatings, are used for applying a coherent coating with excellent properties after heat curing are suitable.

It is already known to produce and use thermosetting powdery coating agents based on copolymers which contain glycidyl groups. However, such known products have the disadvantage that they have to be stoved at temperatures above 200 ^° C. in order to obtain stable films.

Attempts are made to reduce the stoving temperatures in such known powdery coating agents Adding accelerators is insufficient to reduce the effect, or the films obtained already yellow during the stoving process, and adhesion problems sometimes occur.

Such known powder coating agents are described in German Offenlegungsschrift 22 40 312, 40 314, 22 40 315, 20 57 577, 20 64 916, 22 14 650 and 22 313.

1. The object of the present invention is to provide a To provide thermosetting, powdery coating agent available, which compared to the known powdery coating agents L in different directions improvements at the same time The one aim is that the powdery coating agent by simple Mixing, homogenizing fusion and joint grinding of the required Components can be produced

2. The powdery product produced by intensive mixing, homogenizing fusion and grinding Coating agent should at the usual storage temperatures between about -40 to + 40 ° C.

3. The coating agent should lead already by baking at about 150 to 180 ⁰ C in about 15 to 30 minutes to good running bubbles and crater-free high gloss non-yellowing coatings after application.

4. The stoved films should not yellow and, in addition to having excellent weather resistance and a significantly improved resistance to organic solvents and Have chemicals, the comparison of these properties referring to such powder coatings which are based on acrylate copolymer.

The invention relates to a powdery coating agent made from a mixture of

(A) a relatively low molecular weight copolymer containing glycidyl groups and is a copolymer of several ethylenically unsaturated compounds

(B) at least one dicarboxylic anhydride in an amount containing 0.4 to 1.0 anhydride group per Epoxy group (Glycidvlgruppe) corresponds to the copolymer

(C) a curing accelerator in the form of an organic base,

(D) a flow control agent in an amount of at least 0.05 percent by weight of the mixture which is a polymer having a molecular weight (Mn) of at least 1000 and a glass transition temperature which is at least 50 ° C lower than the glass transition temperature of the copolymer (A)

characterized in that the coating agent from (A) 84 to 94 percent by weight epoxy and hydroxyl group-containing copolymers, the softening points according to Durran of about 90 to 120 ⁰ C and are soluble in organic solvents and from: a) 6 to 24 percent by weight of ethylenically unsaturated epoxy monomers with 6 to 12 carbon atoms of the general formula

R R

CH = C-RV ₁ -CH-CH ₂ O

where R and R 'denote the radical —H or —CH ₃ and R "denotes the groups

- C-O-CH ₂ -O

or

-CH ₂ -O-CH ₂ -

or

-CH ₂ -OC-CH = CH-CO-CH ₁ -

Ii Il

ο ο

or

represents and where η denotes the value 1 or zero

b) 4 to 20 percent by weight of hydroxyalkyl esters of acrylic or methacrylic acid, the hydroxyalkyl ester group is saturated and contains 2 to 4 carbon atoms

c) 24 to 38 percent by weight of acrylic acid esters of aliphatic saturated monoalcohols with 1 to 8 carbon atoms,

d) 6 to 14 percent by weight methacrylic acid esters of aliphatic saturated monoalcohols with 1 to 8 carbon atoms and

e) 24 to 42 percent by weight of styrene or vinyl toluene are built up, as well as

(B) 6 to 16 weight percent of at least one dicarboxylic acid anhydride having melting points from about ⁰ to 140 C, (C) 0.5 to 1.8 percent by weight N, N'-bis- (Dimethylaminoisobutyliden) melamine and, optionally, (D) the flow regulating means and other common additives

In a preferred embodiment of the invention, component (A) consists of a copolymer made up of:

a) 12 to 16 percent by weight glycidyl methacrylate,

b) 14 to 18 percent by weight of hydroxyethyl methacrylate

c) 24 to 38 percent by weight of ethyl acrylate,

d) 6 to 14 percent by weight methyl methacrylate and

e) 30 to 42 percent by weight styrene.

A special embodiment of the invention is a coating agent according to claim 1, characterized that component (A) is composed of a copolymer made up of:

a) 12 to 18 percent by weight glycidyl methacrylate,

b) 4 to 8 percent by weight of hydroxyethyl methacrylate,

c) 24 to 28 percent by weight of n-butyl acrylate,

d) 6 to 14 percent by weight methyl methacrylate and

e) 38 to 42 percent by weight styrene
consists

A further specific embodiment of the invention relates to the use of the powdery coating composition according to one of claims 1 to 3 as a powder coating of between -40 to + 4O ⁰ C lagerungsbe- is "tändig and by baking at about 150 to 180 ⁰ C in about 15 to 30 Minutes, provides bubble and crater-free, high-gloss, non-yellowing coatings that run well

As component a) glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether, Glycidyl crotonate, vinyl glycidyl ether, allyl glycidyl maleate, allyl glycidyl phthalate, butadiene monoxide are used will.

^ ₆

". . . _ U ₁ : - loWeichtspruzent, based on the amount of

As component b) can hydroxyalkyl ester of ärtungsmitte to K> Oew_ ρ _H! used it

Acrylic or methacrylic acid, such as hydroxyathyacrylate, JKSS not known and not to be expected,

Hydroxyethyl methacrylate, hydroxypropyl acrylate, nyw «. j ^^ _known hardeners in quantities below 2

find droxybutyl acrylate, use. Percent by weight, together with dicarboxylic anhydride

As component c), for example, methyl 5 ^Ge ™ ^pr ° _{esc ;, a defining} effect on the anhydride

.crylat, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate dnden em * '^ ^ _{ausflben 6th}

Isobutyl acrylate can be used. _USS £ u _{ngsmittel (D) can be delayed} in the nartumg weraen preferred pulverulent

Ethylacrylate or Butylacrylai used an acrylic polymer with a coating agent

As component d) Find, for example, methyl- ^ ", ^ wSempenitur are used, which to

«Eüacrylarätthylme ^

butyl methacrylate, 2-Athylhexylmethacrylat Verwen- * ^e * ^ ^th> _{the mixture} copolymers used

manure. Methyl methacrylate is preferably used, the temperature in μ

The copolymers are produced according to _e acrylic polymers, which are used as flow regulating agents

known processes of substance, solution and J ™haben ** ™ Zl _n \ _ömen , are polylauryl acrylate,

Dispersion polymerization, preferably by J ^ - -5 tei ve: _Po iy (2nd ethylhexyl acrylate), polylauryl

solution polymerization. Such processes are in the case of lyäode <^ etliaciylat

For example in the book: "Methods of organic " ^ g ^^ SJ, ^ also a fluorinated one

Chemie, H ο ube η - W ey 1, 4th edition, Vol. 14/1, p. 24 P ^ Hubregeiuj ^. ^ _{Burn-in temperature of the}

to 556 (1961K described.. ₂₀ powder mixture has a lower surface tension

Is polymerized in solution, can Losungsjn- * PJlvermisc g _{Μή used} e copolymers

tel, such as methyl chloride, ethanol, iso-propanol. η-Pro- g as aas m _{Flußre e} averaging means a fluorinated

panol, n-butanol, iso-butanol, tert-butano Ess.gsaure- ^^^^ e ^ i ^ are esters from polyethy-

methyl-bis-butyl ester, acetone, methyl ethyl ketone, Ben polymers verwe, _eng , _{yko | and fluorinated} ^? _n

zene, toluene, etc. can be used. Fatty acids preferred. A suitable flow control

The polymerization will be. Temperatures from 40 to 15 J ^^ g ^ ie _an ester of polyethylene glycol

about 120 ⁰ C carried out Sh a molecular weight of over 2500 but below

Percarbonates, with “newJ ^ ^M ° ^ie _fl | _{ctanoic acid} . _{Next can the}

Peresters, such as tert-butyl perpivalate. Peroc oa £ Benzoyl- 20 0OC) and rom ι polyester,

peroxide, o-methoxybenzoyl peroxide, dichlorobenzoylpe- Schmeke ^ Verituteu ^ i. ^^^ y ^

roxide, azodiisobutter dinitrile. , n amounts from 0.5 to 30 ^^ ™ ^ Högl eh. Pigments. Lending means

8 Gih b f monomers e.netzt. ^ Btauc ^^

roxide, azodiisobutter dinitrile. , n Meg ^^^ Högl eh. Pigments. Verla

8 weight percent, are based on monomers, e.ngesetzt. ^ ^ Bt AUC ^ ^^^ _{concert, jche}

will. . ...

Next, customary molecular weight regulators we ^to ^ ^U "^ _ _{un smittelfreien>,} where appropriate pigmented

in a vacuum or in dense devices, preference is given to em about ^^ ™ ^^^

white _S «evaporating screws. at temperatures of «^ ¹ ™» J '^

⁴ °

Water vapor and simultaneous dispersion in gen g

Reduce water or by precipitation with water from a groove _b ^^ Jj ^ _;

Water-miscible solvent. ^nes ".I 'j." _ha : T ^ mm-ratiiren ah nn ° r

A.sDicarbons _ä ureanh _y dride (Kom _P onenteB) are ₄₅ ^^^^ ^ ΓΓ ^ ηηί where

hdd

Phthalic anhydride, p-chlorophthalic anhydride, vTrn ^ toKerfo'lgt

ÄSSÄSÄÄ ^ *. -, rait sssmas

D.rfecylberns.einsäureanhydrii. ^el * ° ^s SStalmS F, tΓ dS "rfmdungsgemU

Polyazelamic anhydride _{55 at the same time} f _ger elasticity Furthermore, they are characterized by

useful. In general, such anhydrides have a high gloss, very good weather resistance

with a melting point in the range from 60 to 140 ° C and very good resistance to washing lye.

preferred The powders are used to coat household items

As component (C), N, N'-bis- (dimethylamino- rates, of metal parts in automobile construction, of metal parts

isobutylidene) melamine used The production of die- 60 exposed to the elements, such as from

This connection is described in the German Offenlegungsschrift Fassadenblechen, Rohr, Drahtnetzflechten, from Gera

16 20 178 on p. 5 in example 1. It is also used for forestry, agriculture and others

this by the same applicant in the German metal parts for interior design.

Offenlegungsschrift 16 45 190 as a curing agent for In the following examples, the production of the

Epoxy resins have been described. 65 Powders and their uses as electrostatic

This heat-sprayable powder is described in accordance with this preamble. The ones in the examples

agents together with epoxy compounds in specified parts and percentages refer to the

Amounts from 2 to 25 percent by weight, preferably 2 percent by weight, unless otherwise noted.

example 1

424 g are placed in a two-liter stirred pot with a reflux condenser, thermometer and two dropping funnels Toluene before. The toluene is brought to the reflux temperature of about 112 ° C. by heating, and for this purpose, two monomeric mixtures, namely

and
2.

402 g styrene,

429 g ethyl acrylate,

214 g hydroxyethyl methacrylate,

188 g glycidyl methacrylate and

107 grams of methyl methacrylate

62 g of tert-butyl peroctoate and
20 g of toluene

added dropwise. The mixture is then refluxed for a further hour and an additional 4 g of tert-butyl peroctoate are added dropwise. Polymerization is then carried out for a further 2 hours at reflux from about 18 to 120 ° C. The copolymer obtained has a viscosity according to Gardner-Holdt of 0-P as a 50% solution in toluene at 2O ⁰ C measured. After adding 5.5 g of a polymer-based flow regulating agent (described in Technical Report 04-1 [G] ME-3 [5-71] from Monsanto [Deutschland] GmbH, Düsseldorf), the toluene is distilled off by heating up to 160 ^° C. and under reduced pressure at 40 torr, a brittle, readily pulverizable, clear solid resin was obtained.

300 g of the solid resin obtained are added together with 32 g of a dicarboxylic acid anhydride and curing accelerator mixture, consisting of

92 percent by weight tetrahydrophthalic anhydride

drid and

8 percent by weight N, N'-bis- (dimethyiaminoisobutylidene) -

melamine and an addition of pigment, namely 132 g of titanium dioxide (of the rutile type) with a grain size of about 80 to 200 μm

ground. The powder ^{mixture is then mixed in an extruder at 100 °} C. for 4 minutes, the melt is quenched to room temperature and ground to an approximately 80 μm fine grain.

The powdery coating agent is applied to degreased, phosphated, galvanized steel sheets with an electric spray gun and then baked ^{at 180 ° C. for 30 minutes}

The result is coatings with the following properties:

Layer thickness μπι: 46 to 52
Visual progression: 0 to 1
Buckling test: 0
Yellowing: 0 to 1

Xylene resistance 2 hours: 0 Pencil hardness: H5
Erichsen cupping: 8.2
Gloss according to Lange: 108
Cross cut: 0

Example 2

The procedure is as indicated in Example 1, but deviating therefrom is the following monomer mixture used to produce the copolymer:

402 g styrene,

480 g ethyl acrylate,

188 g of hydroxyethyl methacrylate, 122 g of methyl methacrylate and 148 g glycidyl methacrylate

300 g of the solid resin obtained are added together with 20 g of a dicarboxylic acid anhydride and curing accelerator mixture ground according to example 1.

The stoved coatings show similar properties with better flow than the coatings that have been prepared according to Example 1.

Example 3

The procedure is as indicated in Example 1, but deviating therefrom is the following monomer mixture used to produce the copolymer:

45 562 g styrene,
320 g butyl acrylate,
68 g of hydroxyethyl methacrylate, 162 g of methyl methacrylate and
228 g glycidyl methacrylate

300 g of the solid resin obtained are mixed together with 20 g of a dicarboxylic anhydride and hardening mixture according to Example 1 according to Example 1. The mixture is ausgezeichnei storage stable at 35 to 4O ⁰ C. The stoved coatings show similar properties with better flow than the coatings produced according to Example 1

Claims (1)

Patent claims: 1. Powder coating agent made from a mixture of (A) a relatively low molecular weight copolymer containing glycidyl groups contains and is a copolymer of several ethylenically unsaturated compounds (B) at least one dicarboxylic anhydride in an amount containing 0.4 to 1.0 anhydride group per Corresponds to epoxy group (glycidyl group) of the copolymer and (C) a curing accelerator in the form of an organic base, (D) a flow control agent in an amount of at least 0.05 percent by weight of the mixture, which is a polymer having a molecular weight (Mr.) of at least 1000 and a glass transition temperature which is at least 50 ^° C. lower than the glass transition temperature of the copolymer (A) is characterized in that the coating agent from (A) 84 to 94 percent by weight epoxy and hydroxyl group-containing copolymers, the softening points according to D urran of about 90 to 12O ⁰ C and are soluble in organic solvents and from: a) 6 to 24 percent by weight of ethylenically unsaturated Epoxy monomers with 6 to 12 carbon atoms of the general formula