CH618193A5 - Process for the preparation of isocyanate-crosslinkable copolymers, and the use thereof - Google Patents

Description

The invention relates to a process for the preparation of hydroxyl-containing copolymers which can be crosslinked with di- or polyisocyanates by solution polymerization, characterized in that the following components are copolymerized:

(a) carboxyl-free, hydroxyl-containing esters a, β-ethylenically unsaturated mono- or polycarboxylic acids with di- or polyols or mixed esters of polycarboxylic acids with monoalcohols and di- or polyols,

(b) copolymerizable, hydroxyl- and carboxyl-free vinyl and / or vinylidene compounds, and optionally

(c) a, β-ethylenically unsaturated carboxylic acids,

and that the components are chosen so that the

Hydroxyl number quotient

OH number primary

Secondary OH number in the copolymer is between 1 and 2 and its total hydroxyl number is between 60 and 200 mg KOH / g copolymer.

In a modified process, component (c) monoepoxy compounds can be added to form esters containing hydroxyl groups.

In a further embodiment of this process, the ratio between primary and secondary hydroxyl groups required according to the invention can be achieved by reacting carboxyl groups with monoepoxy compounds during or after the polymerization.

The copolymers prepared according to the invention, in combination with di- or polyisocyanates, give excellent binders for coatings which cure without problems without the addition of crosslinking catalysts. Due to the presence of hydroxyl groups of different reactivity, curing takes place in two stages, which merge into one another. This results in a uniform shrinkage-free curing, so that the films have particularly good mechanical and chemical resistance and z. B. are completely insensitive to abrasion, cold, vibration, water. The drying takes place quickly, but not shockingly; the processing time (pot-life) is more than sufficient.

The copolymers can be prepared by free-radical mixed polymerization of the monomers in solution at reflux temperature using regulators.

As usual, solvents can be used as solvents in which both the monomers and the copolymers are soluble and which do not have a reactive H atom. Esters, ester ethers, aromatic hydrocarbons, e.g. B. ethyl acetate, butyl acetate, ethyl glycol acetate, xylene,

Toluene, etc. are suitable for the process.

The molecular weight of the copolymers obtained according to the invention can comprise a wide range; however, low molecular weights are preferred for processing reasons.

Suitable monomers bearing hydroxyl groups are:

2nd

s io

IS

20th

25th

30th

35

40

45

50

55

60

65

618193

Monoesters of (meth) acrylic acid with glycols such as ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol; 1,4-butylene glycol; with polyols, such as glycerol, trimethylol-propane, etc., the diesters of itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, mesa-cons acid and aconitic acid with glycols or polyols are also suitable.

The mixed esters of the dicarboxylic acids mentioned are also suitable, a carboxyl group with monoalcohols, for. B. methanol, ethanol, sutanol, and the second carboxyl group is esterified with glycols or polyols. In addition, mixed esters of dicarboxylic acids with glycols or polyols can be used.

For the particular embodiment of the in-situ formation of the hydroxyl groups from monomers or copolymers carrying carboxyl groups, monoepoxide compounds, such as glycidic esters of carboxylic acids with 9-11 C atoms, are particularly suitable, the carboxyl group being bound to a tertiary C atom. Furthermore, allyl glycidyl ether, phenyl glycidyl ether and z. B. the glycid (2,3-Epoxipropa-nol-1).

Suitable comonomers are: the esters of (meth) acrylic acid with monoalcohols with 1-12 carbon atoms without functional groups, and the mono- or diesters of the dicarboxylic acids mentioned above with monoalcohols with 1-12 carbon atoms.

Furthermore, other polymerisable vinyl and / or vinylidene compounds, such as styrene, alkylstyrenes, such as o-, m-, p-methylstyrene, p-tert-butylstyrene, a-methylstyrene, (metli) acrylonitrile, (meth) acrylamide and others polymerizable compounds, provided that they can be copolymerized with the other components. Of course, halogen-substituted compounds of the above classes can also preferably be used in all cases.

It is also possible to use esters and ethers of vinyl alcohol, such as methyl, ethyl, propyl vinyl ether, vinyl acetate, vinyl propionate, vinyl stearate, etc., provided that they are copolymerizable with the other components.

The copolymers obtained can be hardened in the usual way with di- or polyisocyanates, such as tolylene diisocyanate, cyclo-hexylene diisocyanate, diphenylmethane diisocyanate.

The films obtained are characterized by great hardness, exceptional elasticity and adhesion to a wide variety

Substrates such as aluminum, zinc, copper, wood and plastics, especially ABS materials. Very quick drying and long processing times enable use on casting machines. The films also have excellent water resistance. They are cold-resistant and insensitive to vibration, properties that play a decisive role, especially when painting winter sports equipment.

The following examples illustrate the invention without restricting it. Parts are parts by weight.

Examples 1-3:

Comparative experiments A and B The monomer solution shown in Table 1 is tert with 2 15 parts of di-tert-butyl peroxide and 2 parts. Dodecylmer-kaptan are added and V3 of this mixture is heated to reflux temperature in a reaction vessel equipped with a stirrer, thermometer and reflux condenser, while supplying inert gas. The rest of the mixture is continuously added over a period of 4 hours and the reflux temperature is maintained for a further 6 hours, with 0.5 part of di-tert.-butyl peroxide dissolved in 1 part of ethylene glycol ethyl ether acetate (2 parts each) and after 4 hours. Ethyl glycol acetate), are added. The reaction is carried out up to a solids content of approx. 60%. The lacquers in all of the following examples and comparative tests are produced using the method just described.

Acrylic resin binder (60%) 65 parts 30 xylene: ethyl glycol acetate:

Methyl isobutyl ketone

10: 7: 4 "

commercial aliphatic polyisocyanate +):

25 parts of commercially available aromatic polyisocyanate +) (solid: solid) 1: 1 25 parts

+) The aliphatic polyisocyanate is a polymerized

Hexamethylene diisocyanate, 75%, in ethyl glycol acetate / xylene, 1: 1.

The aromatic polyisocyanate is a polymerized reaction product of 3 mol of trimethylolpropane and an isomer mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 65%, in ethyl glycol acetate / xylene, 1: 1.

Table 1

example

1

A2)

2nd

B2)

3rd

+ -> ■ M g

2 o

Hydroxyethyl methacrylate

10th

20.9

10th

_

0) CS

Hydroxypropyl methacrylate1)

12

-

-

-

-

Hydroxypropyl acrylate1)

-

-

10th

20th

-

c >>

3 * bit

Dihydroxyethyl itaconate

-

-

-

-

10th

-S ip £ * 5

Dihydroxypropyl itaconate- (1,2)

-

-

-

-

10th

Styrene

40

41.1

42

42

-

§ Ü

Vinyl toluene

-

-

-

-

40

S a e &

Ethyl acrylate

-

-

-

-

35

s £

û O

Butyl acrylate

38

38

38

38

-

s «

S.S.

Acrylamide

-

-

-

-

5

■ i

0)

Solids content%

60

59.5

6 fi

59

61

Viscosity DIN 53 211, s 50% in ethyl glycol acetate

47

53

50

5

75

"n

OHZ total

90

90

86

86

96

OHZ primary

57

90

56

26

52

OHZ secondary

33

_

30th

60

44

SB

Hydroxyl number quotient

1.73

1.87

0.43

1.18

618193

Table 1 (continued)

example

1

A-)

2nd

B>)

3rd

£ 3 * ■ 0

t / 3

Non-sticky (after min.)

60

120

40

120

30th

O

Potlife (in hours) 4)

18th

7

24th

9

12

Pendulum hardness (König, s) s)

104

52

88

61

138

u CS

Adhesion to aluminum (kp / cm2) 6)

205

120

190

140

270

O

Adhesion to ABS film (kp / cm2) 6)

170

100

180

120

200

o it

Water resistance (24 hours / 25 ° C) 7)

U

LB

U

B

U

Explanations to Table 1

1. The monomer used had a ratio of primary to secondary hydroxyl groups of 30:70

2nd comparison test

3. Time period between equalization of the reactive components and the gel point. During this period, the mixture shows no particular increase in viscosity and is easy to dilute and process.

4. measured 24 hours after application of the paint films on glass

5. Determination by forehead tensile test:

The sample (painted sheet or foil) is glued between two iron bars with a round cross section and the force at which the coating is torn from the base is determined. The prerequisite is that the bond is stronger than the adhesive strength of the paint on the sheet.

7) U = unchanged

E = softening

LB = slight blistering

B = blistering

15 parts 8.6 parts 24 parts

45 parts 7.4 parts 60 parts 2 parts 2 parts

Example 4 Hydroxyethyl acrylate methacrylic acid

Glycidyl ester of a tert. Carboxylic acid with 9-11 atoms and an acid number of 300 mg KOH / g styrene

Ethyl acrylate

Ethyl glycol acetate di-tert. butyl peroxide tert. Dodecyl mercaptan are mixed and polymerized analogously to Example 1 up to a solids content of 60% or in situ with the monoepoxy

connection implemented.

Example 5

5.0 parts

Hydroxyethyl acrylate

7.2 parts

Acrylic acid

7.4 parts

Glycid (2,3-Epoxipropanol-l)

40.4 parts

Styrene

40 parts

Butyl acrylate

60 parts

Ethyl glycol acetate

2 parts

Di-tert. butyl peroxide

2 parts tert. Dodecyl mercaptan are polymerized or reacted analogously to Example 4 up to a solids content of 60%.

IS

Example 6

11.5 parts acrylic acid 20.0 parts hydroxybutyl acrylate (1,4)

15.0 parts of vinyl acetate 20 20.5 parts of methyl methacrylate 33.0 parts of butyl acrylate 60.0 parts of ethyl glycol acetate 2.0 parts of di-tert. butyl peroxide

3.0 parts tert. Dodecyl mercaptan

25th

are polymerized analogously to Example 1 up to a solids content of 60% and then set with 18.5 parts of allyl glycidyl ether at reflux temperature up to an acid number of 8.2 mg KOH / g and a solids content of 65%.

Example 7

7.1 parts of acrylic acid

15.0 parts of hydroxyethyl methacrylate 35 5.0 parts of acrylonitrile 45.0 parts of tert. Butyl styrene 27.9 parts of 2-ethylhexyl methacrylate

60.0 parts of methyl glycol acetate 2.0 parts of di-tert. butyl peroxide

40 2.0 parts of tert-dodecyl mercaptan

15.1 parts of phenylglycidyl ether is polymerized or reacted analogously to Example 6.

In this case, 0.5 part of di-tert-butyl peroxide, dissolved in 1 part of methyl glycol acetate, is sufficient to achieve the solids content.

Example 8

20 parts of hydroxyoxapentyl maleate - 1.5 5.4 parts of styrene and 23.6 parts of the glycidyl ester from Example 3 60.0 parts of ethyl glycol acetate 2.0 parts of di-tert. butyl peroxide 3.0 parts tert. Dodecyl mercaptan ss

60

are polymerized or reacted analogously to Example 4.

To achieve the solids content, a further 0.5 part of di-tert-butyl peroxide, dissolved in 1.0 part of ethyl glycol acetate, must be added after a reaction time of 6 hours.

The resin and coating characteristics of Examples 4 to 8 are summarized in Table 2.

5

Table 2

618193

example

4th

5

6

7

8th

Solids content%

59.5

61

65

65.5

59

'Ö

Viscosity DEN 53 211, s 50% in ethyl glycol acetate

78

65

80

1208)

225

.5

Acid number mg KOH / g

8.7

5.7

8.2

8.1

12

ed u

OHZ total

128.5

160

139

122

112

•O

OHZ — Primary

72.5

104

78

65

56

B

OHZ - secondary

56

56

61

57

56

Hydroxyl number quotient

1.3

1.86

1.28

1.15

1.0

CA.

Non-sticky (after min.)

60

30th

40

60

"Ü

<D

Potlife (in hours) 4)

15

12

15

20th

| k> <

Pendulum hardness (König, s) 5)

112

118

109

84

M

«3

Adhesion to aluminum (kp / cm2) 6)

180

240

170

200

O M

Adhesion to ABS film (kp / cm2) 6)

210

170

140

210

O ctf

Water resistance (24 hours / 25 ° C) 7)

E

U

U

U

4) -7) see Table 1

8) 50% in methyl glycol acetate

B

Claims (6)

618193 PATENT CLAIMS 1. A process for the preparation of hydroxyl-containing copolymers which can be crosslinked with di- or polyisocyanates by solution polymerization, characterized in that the following components are copolymerized: (a) carboxyl-free, hydroxyl-containing esters of o, β-ethylenically unsaturated mono- or polycarboxylic acids with di- or polyols, or mixed esters of polycarboxylic acids with monoalcohols and di- or polyols, (b) copolymerizable, hydroxyl- and carboxyl-free vinyl and / or vinylidene compounds, and optionally (c) a, β-ethylenically unsaturated carboxylic acids, and that the components are chosen so that the hydroxyl number quotient OH number primary OH number secondary in the copolymer is between 1 and 2 and its total hydroxyl number is between 60 and 200 mg KOH / g copolymer. 2. Process for the preparation of hydroxyl-containing copolymers which can be crosslinked with di- or polyisocyanates by solution polymerization, characterized in that the following components are copolymerized: (a) carboxyl-free, hydroxyl-containing esters a, β-ethylenically unsaturated carboxylic acids with diols or polyols, (b) copolymerizable vinyl and / or vinylidene compounds bearing no free hydroxyl and carboxyl groups, and (c) a, β-ethylenically unsaturated carboxylic acids, that free or carboxyl groups are reacted with monoepoxides during or after the copolymerization to form hydroxyl-containing esters, and that the components are chosen so that a primary / secondary hydroxyl number quotient of 1 finally results in the end product to 2 and a total hydroxyl number of 60 to 200. 3. Use of the copolymers obtained by the process according to claim 1 for the production of coatings in the presence of di- or polyisocyanates as curing agents. 4. Use according to claim 3 for the production of coatings on winter sports equipment. 5. Use of the copolymers obtained by the process according to claim 2 for the production of coatings in the presence of di- or polyisocyanates as curing agents. 6. Use according to claim 5 for the production of coatings on winter sports equipment. Copolymers containing hydroxyl groups are described in British Patent Specification 1,011,162, German Patent Application 1,121,811 and German Laid-Open Specification 1,621,823 and 2,054,231, which can be crosslinked with di- or polyisocyanates. All these products have in common that they usually contain only primary or only secondary hydroxyl groups for reaction with the isocyanate. In individual cases where the raw materials are not exactly defined, it could be assumed that in addition to secondary hydroxyl groups, minor amounts of primary hydroxyl groups are available in the copolymer. So z. B. the hydroxypropyl methacrylate, depending on the manufacturing process, contain 0-30% of its hydroxyl groups as primary hydroxyl groups. It has been shown that these products are not suitable as binders for paints that are subject to very extreme requirements, because they either have too much shrinkage and therefore poor adhesion to various substrates such as wood, aluminum or ABS film, or require too long a curing time, which delays the further processing of the workpieces in the machines. It has now been found that the difficulties which arise in particular in the series production of skis or other sports equipment can be overcome if the copolymers used in the coating compositions have an optimally balanced ratio of primary and secondary hydroxyl groups in specific amounts.