DE1208023B - Process for the production of storage and gelation-resistant coating agents based on aqueous polyacrylate dispersions - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

Number:
File number:
Registration date:
Display day:

C09d

German KL: 22 g -10/01

1208 023
P18353IVc / 22g
April 15, 1957
December 30, 1965

The invention relates to the preparation of stabilized, non-gelling aqueous dispersions which contain ammonium salts contain certain acidic acrylonitrile copolymers.

From French patent specification 1105 357, useful acidic copolymers are known, which from a monomer mixture obtained from acrylonitrile, an α-olefinic monocarboxylic acid and an ester of an -olefinic monocarboxylic acid with a saturated, aliphatic, monohydric alcohol with 1 to 8 carbon atoms. These acidic copolymers are particularly suitable in the form of aqueous dispersion as a coating and impregnating agent.

Although the above-described aqueous dispersions of acidic copolymers are more satisfactory Manner on a wide variety of substrates to yield useful coated or impregnated objects can be applied, but they have in packaging and the Storage some unfavorable properties.

As a rule, the acidic dispersions cannot be stored in conventional metal containers. but their storage must be in glass or metal containers to avoid contamination take place an inner protective coating which is inert to the aqueous dispersion. Even with filling in such containers, however, the acidic dispersions develop coagulates and coagulates during storage Deposits of the polymer, especially when handling the material mechanical shear forces come into play, z. B. the dispersion is pumped or vigorously stirred will. Another disadvantage of this acidic dispersion is that it is less Have viscosity than is usually desired for most uses. These However, dispersions can, as is sometimes the case, with ammonium hydroxide on them adjusts a pH value between 7 and 10 without the development of precipitates or coarse particles Sediments are stored, pumped, or agitated; however, their viscosity then increases as a rule too much and they tend to gel, especially when stored for a long time. The speed with which increases the viscosity of these dispersions is so great that it has only been stored for a few weeks Material is either gelled or for use using conventional means has too high viscosities.

The object of the invention is therefore to create improved aqueous dispersions of copolymers, processes for the production of storage and
gelation-resistant coating agents on the
Based on aqueous polyacrylate dispersions

Applicant:

E. I. du Pont de Nemours and Company,

Wilmington, Del. (V. St. A.)

Representative:

Dipl.-Ing. E. Prince and Dr. rer. nat. G. Hauser,

Patent attorneys,

Munich-Pasing, Ernsbergerstr. 19th

Named as inventor:

Philip Francis Sanders, Lima, Pa. (V. St. A.)

Claimed priority:

V. St. v. America April 16, 1956

of the above group, which is characterized by excellent viscosity stability, storage stability and resistance to gelation. The dispersions obtained according to the invention also have an improved, constant viscosity and make the use special No need for a container to avoid contamination.

The objects of the invention are achieved in that the pH value is known per se Way obtained aqueous dispersion of a copolymer from

A. 30 to 80 parts by weight of acrylonitrile,

B. 1.5 to 15 parts by weight of an «-olefinic monocarboxylic acid, such as acrylic acid, methacrylic acid, Phenylacrylic acid or crotonic acid, and

C. 15 to 65 parts by weight of an ester of an acid of B with a saturated, aliphatic, monovalent one Alcohol with 1 to 12 carbon atoms

by adding ammonia with the formation of an ammonium salt increased to 5.5 to 8.0, the ammoniacal Dispersion about 5 minutes to 4 hours

509 760/327

I 208 023

3 4

heated to about 45 to 95 ³ C and then to below about indirectly after the polymerization, the

30 ⁰ C cools. Ammonium hydroxide is added in one step,

In many cases, it is advisable to take the coagulate and the settled coarse before coating and taking

Impregnate the aqueous dispersion of the mixed polymer particles before the ammoniacal neutralimers with a dilutable with water, separated in the 5 sation from the acidic composition

Heat reactive aldehyde condensation resin. The preferred heat treatment lasts

z. B. a phenol-formaldehyde resin to modify. about 15 minutes to about 2 hours at a temperature

Although the component C of the acid mixing temperature between about 65 and about 90 ⁰ C. An only

polymer forming preferred monomeric esters heating for 5 minutes at a temperature Butyl acrylate is, however, other esters of io can yield within this temperature range in the

Acrylic acid or the other acids mentioned usually have a viscosity increase of at least 50%

a saturated, aliphatic, monohydric alcohol versus the viscosity of the untreated aqueous one

with 1 to 12 carbon atoms is the monomeric butyl starting dispersion.

acrylate in the preparation of the examples If the ammoniacal neutralization in two

copolymers described is carried out in whole or in part in 15 stages, the heating is in the

substitute. Typical alcohols with 1 to 12 carbon - first neutralization stage are not important because

Atoms are, among other things, methyl, ethyl, propyl, the increase in viscosity is not the main purpose of the

Butyl, isobutyl, hexyl, cyclohexyl, octyl and first stage. With this initial ammoniacal

Lauryl alcohol. The ammonium hydroxide can neutralize it

The production of the copolymers is not part of the process after the end of the emulsion polymerization

within the scope of the present invention and can be added to the prevailing temperature, which

z. B. on the French patent mentioned between room temperature and about 70 ⁰ C and

type described in writing 1105 357. is usually at least about 45 ° C. the

To neutralize the acidic aqueous mixed polyammoniacal neutralization of the second stage

merisate dispersion, the pH of which is generally not a pH in the range from 6.7 to 8.0, which

is above about 4.0, this is so much ammonium - with further heating, the result

hydroxyd added that the pH value increases to about 5.5 actual viscosity increase,

increases. The most preferred method of preparation usually used to achieve this

pH value added amount of ammonium hydroxide of a coating compound, the acidic, aqueous

is sufficient to keep at least 10 percent by weight of the copolymer dispersion in the heat

acidic component of the copolymer in the reactive aldehyde condensation resin,

To transfer ammonium salt. At a pH value is carried out in such a way that the acidic dispersion

between 5.5 and 6.5 is the viscosity of the ammo in the first stage at a temperature between 45

niacal aqueous dispersion compared to the not and 65 ° C with ammonia to a pH of 5.5

neutralized acidic aqueous dispersion not strongly neutralized 35 to 6.5, then filtered, the partially neutralized

improved, and it must with this ammonia content aqueous dispersion with the reactive in the heat

mostly unwanted precipitates and coarse-grained, capable aldehyde condensation resin mixes in the

Separated polymer particles from the dispersion are removed from the second stage to a pH between 6.7 and 7.5

separates, e.g. B. be filtered off. neutralized with ammonia, to increase the

One waits with the separation of the coagulate and the viscosity of the composition at 65 to 90 ^° C. of the coarse-grained polymer particles until after the heating and cooling to room temperature. Appropriate ammoniacal heat treatment at a high temperature is the heat reactive aldehyde condensate pH of z. B. between 6.7 and 8.0, whereby sationsharz in an amount between 2 and 40 ⁰ I ₀ , the viscosity is considerably increased, this is based on the weight of the dispersed ammonium separation difficult with common and practical 45 salts of the mixed polymer, is present. Usually means to carry out. If the separation takes place before the end product is filtered, in order to partially dry out the copolymer dispersion in the acidic dispersion used for the heat treatment to a pH of at least 5.5 in the acidic dispersion used for the heat treatment, then under acidic detes, coagulate coagulate is formed to remove.
Conditions, ie at a pH value below 5.5, 5 ° The stabilized, aqueous copolymer dispersions can further coagulate and ions with pigments, fillers and coarse polymer particles settled with pigments, fillers. In the case of industrial extenders, finely divided, water-swellable implementation, the ammonium-containing silicates, such as bentonite and Montniacal neutralization, are therefore expediently carried out in two stages with a morillonite, dyes and compatible film-forming intermediate separation or filtration. Can be modified in 55 resins and plasticizers. In contrast to the first stage, the ammoniacal neutralization takes place, if necessary, the cation obtained according to the invention can be reduced to a pH of 5.5 to 6.5, and in compositions when they are used with the second stage, the ammoniacal neutralized ammonium hydroxide or volatile amines are reduced to one sation up to a higher pH than that of the higher ammoniacal pH between 8.0 first stage, namely up to a 60 and 10.0 can be set. In some cases pH 8.0 and preferably 6.7 and 7.5 results. this higher alkalinity a better wettability of the substrate added overall in the two stages.

Amount of ammonium hydroxide is sufficient to transfer the aqueous dispersions according to the invention

from 50 to about 100 percent by weight of the acidic, up to 50 percent by weight of dispersed am-

Component of the copolymer in the ammonium monium salt of the acidic copolymer and up to

salt out. down to 5% included. Usually the practical one lies

If the ammoniacal heat treatment is carried out, the content of the mixed polymer is between 10 and 45

of the acidic aqueous copolymer dispersion by weight.

The following specific examples show preferred ones Embodiments of the invention. Unless otherwise stated, parts and percentages are given on a weight basis.

example 1

A copolymer dispersion of the type known per se was obtained from the composition below Way made:

Parts by weight

Water 62.695

Sodium metabisulfite 0.035

Sodium Lauryl Sulphate 0.19

Acrylonitrile monomer 22.00

Monomeric methacrylic acid 1.80

Monomeric butyl acrylate 11.20

Potassium persulfate solution

(5.0 weight percent in water) 2.08

100.00

IO

30th

The resulting aqueous dispersion of the acidic copolymer has a non-volatile content Ingredients of 34.5 percent by weight have a pH of 3.8 and are characterized by a medium Particle size of 0.22μ. The mixed polymer separated from the aqueous dispersion has a relative viscosity of 6.6 as determined with an ASTM No. 200 Ostwald-Cannon-Fenske viscometer at 25 ° C using dimethylformamide as the solvent for the preparation of the test solution with a content of 0.5 percent by weight of the copolymer.

This non-stabilized aqueous copolymer dispersion according to Example 1 was filtered through felt and then divided into individual shares, each of which was treated as follows; every stake was made before its use with distilled water to a non-volatile content of 30 percent by weight diluted.

Sample A. Only diluted with distilled water without further treatment.

Sample B. The aqueous dispersion was adjusted to pH 9.0 with ammonium hydroxide neutralized and diluted.

Sample C. Diluted with distilled water, ^{heated to 75 °} C. for about 5 minutes, kept at this temperature for 15 minutes and then immediately cooled to room temperature.

Sample D. Ammonia neutralized to pH 7.5 as described for Sample C. heat-treated at 75 ° C and immediately cooled.

Sample E. Treated as described for Sample D, except that the ammoniacal Neutralization to a pH of 9.0 occurred.

Sample F. Heat treatment as described for sample C. and subsequent ammonia neutralization to a pH of 9.0.

Sample G. Initially neutralized with ammonium hydroxide to pH 7.5, such as for sample D described and then heat treated to a pH of 9.0 using Ammonia neutralizes.

The viscosity of these samples was determined in each case with a Brookfield viscometer at 25 ° C. the Samples were then stored in an oven at 50 ° C, periodically removed from the oven, to 25 ° C cooled, and to determine the influence of storage at 50 ° C on the viscosity stability was their viscosity measured.

The viscosity values for all samples are given in Table 1 below in centipoise.

Table 1
Influence of storage at 50 ° C. on viscosity stability

■ viscosity sample
AIBICIDIEIFIG 160
1600
12,000
38,000
69,000
gelled 20th
20th
20th
30th
120
120
16,000 120
60
60
60
50
50
50
50 9,000
9 200
27,000
40,000
gelled 140
920
1000
1240
9,000
12,000
15,000 700
700
1060
1100
8 500
10,000 At the start
28 days
42 days
50 days
80 days
94 days
108 days
164 days 20th
20th
20th
20th
55
60
7000

The values in Table 1 show that sample D, in which the acidic dispersion to a pH of 7.5 neutralized and then subjected to a heat treatment, an exceptionally good viscosity stability exhibited. This sample did not gel or did not show any even after years of storage noticeable increase in viscosity. It remained package stable, did not coagulate, and did not form fine Polymer grit. Samples A and C, i.e. H. the non-neutralized dispersions show only a moderate one Viscosity stability, are not package stable, and heating improves the initial viscosity not. The samples that have been stored for longer coagulate, and a fine polymer grit is formed in them.

Sample B has a favorable initial viscosity, which, however, is unstable and after 28 days of storage rises to a practically unusable value. Sample E corresponding to sample B, but which is heat-

has already been treated with an unusually high initial viscosity and gels even faster than the sample B.

The data for Samples F and G show that when the pH of the heat-treated aqueous Copolymer dispersions in which the copolymer is either in its acidic form or as Ammonium salt is present, is increased to 9.0, the products do not have a stable viscosity.

Similar or even more pronounced differences in storage and gelation stability is achieved when the copolymer dispersion is also a heat-reactive aldehyde condensation resin contains. This resin can be added to the dispersion before or after the ammonia neutralization be admitted; However, the best results are achieved if the addition takes place before the ammonia neutralization he follows.

Example 2

As in Example 1, the following constituents were initially used to produce a copolymer dispersion manufactured:

Parts by weight

Acrylonitrile monomer 26.10

Monomeric butyl acrylate 13.35

Monomeric methacrylic acid 2.07

Sodium Lauryl Sulphate 0.22

Sodium metabisulfite 0.04

Potassium persulfate 0.12

Distilled water 58.10

100.00

The dispersion obtained had a polymer content of 41.0%, its pH was 3.7 at 25 ° C, and the average particle size of the copolymer was 0.25 μ. The relative viscosity of this copolymer was 6.3 when dimethylformamide was used as the solvent. The unstabilized acidic aqueous copolymer dispersion was filtered through felt before further treatment.

The following composition was then made:

Parts by weight

Unstabilized aqueous
Mixed polymer dispersion 70.40

Dilutable with water in which
Heat reactive phenol-formaldehyde resin, 66 percent by weight in water 4.85

29% NHa solution 0.70

Distilled water 24.05

100.00

The stated amount of ammonium hydroxide was sufficient to increase the pH from 3.7 to about 7.65 the end.

The composition, well mixed at room temperature, was subjected to the following heat treatment subjected:

a) heated ^{to 45 °} C. within 5 minutes;

b) heated ^{to 65 °} C. within a further 5 minutes;

c) heated to 85 ° C. within a further 5 minutes and held at this temperature for 120 minutes.

At 45, 65, 85 ° C and at intervals during the residence of the temperature to 85 ⁰ C samples were taken. Table 2 below shows the viscosity values obtained for these samples at 25 ° C. using a Brookfield viscometer:

Table 2

Influence of the heating time on the
Viscosity increase

sample

Starting mixture

a) after heating to 45 ° C in 5 minutes

b) after heating to 65 ^° C. in 10 minutes

c) after heating to 85 ^° C. in 15 minutes

d) after staying at 85 ° C. for 10 minutes

e) after staying at 85 ° C for 20 minutes

f) after 30 minutes at 85 ° C

g) after 60 minutes at 85 ° C
h) after 90 minutes at 85 ° C

i) after staying at 85 ° C for 120 minutes

viscosity

30 65 110 210 245 235 235 210 170 170

These values show that the neutralized aqueous solution is used to achieve a favorable increase in viscosity The dispersion only needs to be heated for a relatively short time. The will decrease with longer heating The viscosity of the product fell slightly below the maximum value and reached a constant one Final value.

All of the samples described above were storage and viscosity stable and gelled during storage at room temperature for at least 1 year.

Example 3

Parts by weight

Water 59.05

Sodium metabisulfite 0.03

Sodium Lauryl Sulphate 0.20

Acrylonitrile monomer 24.20

Monomeric methacrylic acid 1.92

Monomeric butyl acrylate 12.30

Potassium persulfate solution

(5.0 weight percent in water) 2.30

100.00

The unstabilized aqueous dispersion obtained from this composition had a pH value of 3.8, an average particle size of the interpolymer in the dispersion of about 0.20 μ, and one Content of the copolymer of 37.5 percent by weight. The interpolymer had a relative Viscosity of 6.5.

After the end of the polymerization, the acidic aqueous copolymer dispersion was neutralized at a temperature of 60 ° C. and with 0.15 part of ammonium hydroxide (29% NH ₃ ) to a pH between 5.5 and 6.5. This amount of ammonium hydroxide was sufficient to neutralize at least 10 percent by weight of the methacrylic acid component contained in the copolymers. The mixture was heated to 45-60 ° C for about 30 minutes, then filtered through felt, transferred to a storage container for later use, and cooled to room temperature. It had a stable viscosity that was low enough for normal filtrations, remained stable during storage and could be heated again after filtration, cooled and then subjected to mechanical forces, such as stirring or

Pump effects, are exposed without deposits or coagulates being formed.

The product described above was then mixed with a solution of the following composition mixed:

Dilutable with water, in the heat
reactive phenol-formaldehyde resin (66 percent by weight in
Water) 6.45

Water 21.30

27.75

The mixture was then heated to 87 ° C. with stirring and 1 part of ammonium hydroxide (29% NH ₃ ) was added for further neutralization up to a pH of 7.2. The total amount of ammonium hydroxide added with the two portions was sufficient to neutralize about 90 percent by weight of the methacrylic acid component of the mixed ao polymer.

The resulting mixture was 70 minutes at a speed of 120 revolutions per Minute without further supply of heat or support of cooling. Then you cooled that Product down to room temperature and filtered coarse foreign matter, e.g. B. skins of the polymer.

If necessary, the two-step process described in this example can also be used without intermittent cooling and storage can be carried out. The filtered product of the ammoniacal Neutralization of the first stage can be transferred warm or hot into the mixing device in which by mixing with the heat-reactive phenol-formaldehyde resin, second ammoniacal neutralization and heat treatment to increase and stabilize the Viscosity of the final product is obtained.

In both the single stage as well as in the two step process showed the stabilized product obtained is excellent in storage stability and stability of viscosity at ljähriger storage at 45 or 25 ⁰ C and was on storage at 5O ⁰ C at least 8 months stable.

The stable aqueous copolymer dispersions have a wide range of uses in coating and impregnating objects. They make excellent thermosetting paints for electrical Wire insulation and excellent air drying varnishes for wood, e.g. B. for bowling alleys and cones. They can be used on metallic and non-metallic substrates either as thermosetting or air-drying Coatings are applied and are particularly suitable as impregnating agents for fabrics and nonwoven webs of synthetic fibers, e.g. B. made of polyacrylonitrile, polyethylene terephthalate, Nylon, rayon, polyurethane, polytetrafluoroethylene, and polyvinylidene chloride. They can also be used to coat and impregnate objects made of natural fibers such as cotton, Jute, sawdust pulp, and chemical wood pulp, can be used. Woven and non-woven Fabrics made of glass fibers can be coated and impregnated with it. When using the impregnation agent for other than woven fabrics, the 6g weight ratio of dry impregnant can be used to the fiber can be varied, so that one obtains products whose properties are between thin, paper-like sheets or leather-like fabrics to thick, rigid sheets vary.

The invention offers a distinct advantage over the prior art, since it is technical creates valuable ammoniacal aqueous dispersions of mixed polymers in salt form, which is characterized by a previously unattained storage stability, resistance to gelation and Characterize the stability of the viscosity. The invention also enables the production of stable aqueous compounds Mixed polymer dispersions with improved viscosity.

Claims (4)

Patent claims: 1. Process for the production of storage and gelation-resistant coating agents based on aqueous polyacrylate dispersions, characterized in that the pH is obtained in a known manner aqueous dispersion of a copolymer from A. 30 to 80 parts by weight of acrylonitrile, B. 1.5 to 15 parts by weight of an α-olefinic Monocarboxylic acid, such as acrylic acid, methacrylic acid, phenylacrylic acid or crotonic acid and C. 15 to 65 parts by weight of an ester of an acid of B with a saturated, aliphatic, monohydric alcohol with 1 to 12 carbon atoms by adding ammonia with the formation of an ammonium salt increased to 5.5 to 8.0, the ammoniacal Dispersion heated to about 45 to 95 ° C for about 5 minutes to 4 hours and then heated up cools below about 30 ° C. 2. The method according to claim 1, characterized in that the neutralization with ammonia is carried out in two stages with intermittent separation of coagulate formed and coarse polymer particles, the neutralization in the first stage up to a pH of about 5.5 to 6 , 5 and the neutralization in the second stage takes place at 45 to 95 ⁰ C until the pH of the aqueous dispersion is adjusted to between 6.5 and 8.5. 3. The method according to claim 1 and 2, characterized in that the aqueous dispersion the mixed polymer also has a heat-reactive aldehyde condensation resin that can be diluted with water, z. B. a phenol, urea, melamine, urea-melamine-formaldehyde resin or a mixture of such resins in one Amount between 2 and 40%> based on the weight of the dispersed ammonium salt, adds, and preferably before the second ammonia neutralization. 4. The method of claim 2 or 3, characterized in that which is made in the second heat ammoniacal neutralization by 15-bis 120minutige heating at 65 to 9O ⁰ C. Considered publications:
French Patent No. 1105 357. 509 760/327 12.65 © Bundesdruckerei Berlin