DD239801A5 - Flame protection based on ammonium phosphate - Google Patents

Abstract

The present invention relates to a flame retardant based on free-flowing powdery ammonium polyphosphate of the general formula H (nm) 2 (NH 4) mPnO 3n 1 in which n is an integer with an average value of about 20 to 800 and the ratio of m to n is about 1 wherein the agent of a) consists of about 75 to 99.5% by weight of ammonium polyphosphate and b) about 0.5 to 25% by weight of a reaction product of a polyisocyanate with a carbodiimidization catalyst, wherein the polycarbodiimide surrounds the individual ammonium polyphosphate particles, and a method for its production. The result of this invention is a hydrolysis-stable, microencapsulated flame retardant.

Description

in which η is an integer with an average value of about 20 to 800 and the ratio of rri to η is about 1, and consists of a polyisocyanate and a carbodiimidization, for 0.5 to 5 hours with stirring to temperatures between 30 to 200 ⁰ C and then cooled, filtered and dried now microencapsulated with a polycarbodiimide ammonium polyphosphate.

7. The method according to item 6, characterized in that the suspension of diluent and 'ammonium polyphosphate vorlegTund of this suspension solutions of the polyisocyanate and then the '. ''Carbodiimidation catalyst is added slowly in the diluent.

8. The method according to any one of items 6 to 7, characterized in that in the general formula of the ammonium polyphosphate η is an integer having an average value of 450 to 800.

9. The method according to any one of the items 6 to 8, characterized in that as a diluent Lösungsmittehauf basis of aromatic, aliphatic and cycloaliphatic hydrocarbons and aliphatic, aromatic and 'mixed aliphatic / aromatic ketones, preferably acetone, are used.

10. The method according to any one of items 6 to 9, characterized in that are used as the polyisocyanate commercially available aromatic or aliphatic di- and polyisocyanates, preferably technical 4,4'-diphenylmethane diisocyanate (MDI).

11. The method according to any one of points 6 to 10, characterized in that as carbodiimidization j organophosphorus, especially cyclic organophosphorus compounds, preferably 1-methyl-i-oxo-. ? phospholes, are used. j

A process according to any one of items 6 to 11, characterized in that in the suspension a ratio of ammonium polyphosphate diluent, polyisocyanate carbodiimidation catalyst such as 1: 1.5-2.5: 0.05-0.25: Q, 00025-O, 0125, j preferably 1: 2: 0.1: 0.002. ί j

13. The method according to any one of items 6 to 12, characterized in that the reaction time is 1 to 2 hours at temperatures j between 50 ° C to 100 ⁰ C. j

14. The method according to any one of points 6 to 13, characterized in that the drying at temperatures between 80 ° C to. '..'] 150 ° G in an inert gas atmosphere, preferably in a stream of nitrogen, takes place. _:

15. The method according to any one of the points 6 to 14, characterized in that the achieved average particle size of.:, ', ;; microencapsulated ammonium polyphosphate as a flame retardant between 0.01 to 0.1 mm, preferably between ► 0.03 to 0.06 mm. ^vv :

16. The method according to any one of items 6 to 15, characterized in that the proportion of the polycarbodiimide in the flame retardant is 2 to about 15 wt .-%. ,

Field of application of the invention

The invention relates to a hydrolysis-stable, microencapsulated flame retardant based on free-flowing, powdered ammonium polyphosphate and a process for its preparation.

Characteristic of the known technical solution

It is generally known to use ammonium polyphosphates as flame retardants for plastics. For example, DE-AS 1283532 describes a process for the preparation of flame-resistant polyurethanes of high molecular weight;

Polyhydroxy compounds, polyisocyanates and catalysts, wherein an ammonium polyphosphate of the general formula

H (n-m) + 2 (NH4) _m PnO3 _n +1 ',

where η is an integer greater than 10, m is an integer up to at most η + 2, and m / n is between 0.7 and 1.1, proposed as a flame retardant additive.

Although ammonium polyphosphates of the abovementioned general formula, when used in polyurethanes, impart good flame retardancy to the latter, they have the disadvantage that they are not sufficiently water-insoluble and are therefore washed out of the plastic over the course of time by weathering influences. As can be seen from column 3 of DE-AS 1,283,532, which have there to be practically insoluble in water referred ammonium polyphosphates nevertheless a substantial solubility in water, by solving at slurrying 10g of ammonium polyphosphate in 100ml water at 25 ⁰ C up to 5g of the ammonium polyphosphate, ie the soluble portions of the ammonium polyphosphate amount to up to 50% of the amount used.

German Offenlegungsschriften DE-OS 2949537 and DE-OS 3005252 describe processes for the preparation of hydrolysis-stable, pulverulent ammonium polyphosphates by cladding with melamine / formaldehyde resins or phenol / formaldehyde resins. In both cases, the water solubility in Compared to uncoated ammonium polyphosphate significantly reduced.

A disadvantage of the use as a flame retardant, however, is that the coating material releases small amounts of formaldehyde.

Finally, DE-OS 3217816 describes the preparation of hydrolysis-stable, pulverulent ammonium polyphosphates by coating with cured epoxy resins. However, the intended effect of reducing the water-soluble components is less pronounced than with the melamine / formaldehyde resins.

Object of the invention

The aim of the invention is the provision of improved, in particular hydrolysis-stable flame retardants based on ammonium polyphosphate.

Explanation of the essence of the invention *

The invention is based on the object. To find ways and means for reducing the solubility of ammonium polyphosphates in water, so that the risk of leaching of the ammonium polyphosphate when used as a flame retardant in plastics and in wood or paper materials by weathering is avoided as much as possible. Furthermore, it should be ensured that the coating material does not release any pollutants.

It has now been shown and was not foreseeable that the inventive replacement of melamine or phenolic resins by polycarbodiimides is associated with advantages.

Thus, the invention relates to a flame retardant based on free-flowing, powdered ammonium polyphosphate of the general formula

H (n-m) + 2 (NH ₄ ) _m P _n O _{3 n} + 1

in which η is an integer having an average value of about 20 to 800 and the ratio of m to about 1, which is characterized in that it

a) about 75 to 99.5Ma .-% ammonium polyphosphate and

b) about 0.5 to 25% by weight of a reaction product of a polyisocyanate and a carbodiimidization catalyst, the polycarbodiimide coating the individual ammonium polyphosphate particles,

consists. The result of this invention is a hydrolysis-stable, microencapsulated flame retardant.

The agent of the invention generally has an average particle size of about 0.01 to 0.1 mm and the degree of condensation η of the ammonium polyphosphate is preferably an integer with an average value of 450 to 800, determined by the end-group titration method of "van Wazer, Griffiter and Mc Cuilough ", Anal. Chem. 26, p

According to a further preferred embodiment of the agent according to the invention, the proportion of

Polycarbodiimide 2 to about 15Ma .-%. , '.

The polycarbodiimide is a reaction product which is formed by a catalyzed polycondensation of polyisocyanate. The term "polyisocyanate" includes all commercially available aromatic and aliphatic diisocyanates and polyisocyanates, such as are used, for example, for the preparation of polyurethane, polyisocyanurate or polycarbodiimide foams.

The process according to the invention for the preparation of this hydrolysis-stable, microencapsulated flame retardant is characterized in that a suspension which consists of a diluent and free-flowing, pulverulent ammonium polyphosphate of the general formula

H (n - m) +2 (NH4) _{m Pn} O3n + 1

in which η is an integer with an average value of about 20 to 800 and the ratio of m to η is about 1, and consists of a polyisocyanate and a carbodiimidization, for 0.5 to 5 hours with stirring to temperatures between 30 ⁰ C. keeps to 200 ° C and then cooled, filtered and dried now microencapsulated with a polycarbodiimide ammonium polyphosphate

 In detail, the method optionally consists in that

a) initially introducing the suspension of diluent and ammonium polyphosphate and slowly adding to the suspension solutions of the polyisocyanate and then the carbodiimidization catalyst in the diluent;

b) in the general formula of the ammonium polyphosphate η is an integer having an average value of 450 to 800; , '. , '. ,. J. '"/

c) as diluents solvents based on aromatic, aliphatic or cycloaliphatic hydrocarbons and aliphatis'cher, aromatic and mixed aliphatic / aromatic ketones, preferably acetone, are used;

d) as a polyisocyanate commercially available aromatic or aliphatic di- and polyisocyanates, preferably technical 4,4'-diphenylmethane diisocyanate (MDI) are used;

e) as carbodiimidization catalyst organophosphorus, in particular cyclic organophosphorus compounds, preferably 1-methyl-i-oxo-phospholes, are used;

f) in the suspension a ratio of ammonium polyphosphate: diluent polyisocyanate: carbodiimidization catalyst such as 1: 1.5-2.0: 0.05-0.25: 0.00025-0.0125, preferably 1: 2: 0.1: 0.002, is complied with;

g) the reaction time is 1 to 2 hours at temperatures between 5O ⁰ C to 100 ⁰ C;

h) the drying takes place at temperatures between 80 ^° C. to 150 ^° C. in an inert gas atmosphere, preferably in a stream of nitrogen; i) the achieved mean particle size of the microencapsulated ammonium polyphosphate as a flame retardant between

0.01 and 0.1 mm, preferably between 0.03 and 0.06 mm; and ₍ k) the proportion of the polycarbodiimide in the flame retardant is 2 to about 15 mass%.

Finally, the invention also relates to the use of the above-described composition for the flame-retardant adjustment of polyurethanes or polyurethane foams, wherein the content of the agent in the polyurethane foam about 5 to 25Ma .-% based on the amount of the poly component of the polyurethane.

The application of the polycarbodiimides to the ammonium polyphosphate particles can be carried out in solvents based on aromatic, aliphatic or cycloaliphatic hydrocarbons or in aliphatic, aromatic or mixed aliphatic / aromatic ketones while stirring the ammonium polyphosphate / polyisocyanate suspension, wherein the catalyzed polycondensation reaction is carried out with heating.

By enclosing the ammonium polyphosphate particles according to the invention with a polycarbodiimide, the solubility of the ammonium polyphosphate in water is significantly reduced, which has a favorable effect, for. Example, when using such a pretreated ammonium polyphosphates as'Flammschutzmittel in polyurethane foams. The polycarbodiimides are characterized as a coating material for ammonium polyphosphate over the known coating resins phenol / formaldehyde resin and epoxy resin by a higher reduction of water solubility and the melamine / formaldehyde resins and the phenol / formaldehyde resins in that they can not release formaldehyde. Further, the polycarbodiimide coating has the advantage of higher thermal stability over the melamine / formaldehyde resin coating, which has a particularly positive effect on incorporation into thermoplastics having high processing temperatures.

♦ Example of an exercise

The compositions according to the invention, their preparation and advantages are explained in the following examples. To carry out the experiments set out in the examples commercially available ammonium polyphosphates and various, also commercially available polyisocyanates and carbodiimidization were used. Specifically, these are the following products:

1. ®Exolit422 ^x

It is a fine-grained, poorly water-soluble ammonium polyphosphate, wherein the degree of condensation is η ~ 700.

2. ®Caradate 30

It is a mixture of various aromatic di- and triisocyanates with 4,4'-diphenylmethane diisocyanate as. Main component. The product is a liquid of deep brown to black color. The isocyanate content is 30.2% NCO. The density (at 23 ⁰ C) is 1.22 to 1.24 g / ml, the viscosity (at 25 ° C) 160-24OmPa · s.

3. 1-methyl-i-oxo-phospholes,. It is a mixture of isomers of the compounds

and O CH,

with a purity of at least 98%. The product is a yellow-brownish liquid; the density (at 20 ⁰ C) is 1.12 g / ml; the boiling point is 150 ⁰ C to 155 ° C / 33mbar. λ

4. 2-methyl-2-oxo-1,2-oxaphospholane

It is the connection -

with a purity of approx. 95%. The product is a colorless liquid with a density of 1.19 g / ml. The boiling point is 89 ° C / 1,5mbar

 5. 2-Methyl-2,5-dioxo-1-oxa-2-phospholane It is the compound

-4- Z39 BUl

with a purity of 95-98%. The product represents colorless crystals with a melting point of 102 ° C-104 ° C.

example 1

250 g of ®Exolit 422 were suspended in 1000 ml of xylene in a stirred glass apparatus; then a solution of 15 g of ®Caradate 30 in 100 ml of xylene was added dropwise. Subsequently, the suspension was heated to a weak boil and added dropwise with a solution of 0.06 g of a carbodiimidization catalyst [e.g. B. isomer mixture of 1-methyl-i-oxo-phospholene (Hoechst Aktiengesellschaft, Frankfurt am Main) in 50 ml of xylene. After stirring for 2 hours, it was cooled to room temperature and filtered. The resulting filter cake was dried at 130 ⁰ C in a stream of nitrogen. 258 g of coated ammonium polyphosphate having a polycarbodiimide content of 3.9% by weight were obtained. To determine the water-soluble of water were suspended 10 g of the product prepared in 100 ml, and the suspension was stirred 20 min at 25 ⁰ C. Subsequently, the undissolved in water portion of the product was sedimented by centrifugation within 40 minutes. From the supernatant clarified solution, 5.0 ml were pipetted into a previously weighed aluminum dish and evaporated at 12O ⁰ C in a drying oven. From the amount of the evaporation residue, the water-soluble content was calculated. The result is shown in Table 1.

Example 2

The procedure was analogous to Example 1, except that a solution of 30 g ®Caradate 30 in 100 ml of xylene and a solution of 0.12 g of i-methyl-1-oxo-phospholene (isomer mixture) in 50 ml of xylene were used. 270 g of coated ammonium polyphosphate having a polycabodiimide content of 8.8% by mass were obtained. The values determined for the water-soluble fractions are listed in Table 1.

Example 3

The procedure was analogous to Example 1, except that a solution of 45g ®Caradate 30 in 100 ml of xylene and a solution of 0.18 g of 1-methyl-i-oxo-phospholene (isomer mixture) in 50 ml of xylene were used.

275 g of coated ammonium polyphosphate having a polycarbodiimide content of 12.1 mass% were obtained. The values determined for the water-soluble fractions are listed in Table 1.

Example 4

The procedure was analogous to Example 1, except that a solution of 60g ®Caradate 30 in 100 ml of xylene and a solution of 0.24 g of 1-methyl-i-oxo-phospholene (isomer mixture) in 50 ml of xylene were used.

288 g of coated ammonium polyphosphate having a polycarbodiimide content of 15.2 mass% were obtained.

The values determined for the water-soluble fractions are listed in Table 1.

Example 5

In a glass stirring apparatus, 250 g of ®Exolit 422 were suspended in 400 ml of acetone; then a solution of 30 g of ® Caradate 30 in 100 ml of acetone and a solution of 0.03 g of 1-methyl-i-oxo-phospholene (mixture of isomers) in 50 ml of acetone were added. Subsequently, the suspension was heated to a weak boil. After a stirring time of 1 hour, it was cooled to room temperature and filtered. The resulting filter cake was dried at 100 ⁰ C in a stream of nitrogen. 255 g of coated ammonium polyphosphate having a polycarbodiimide content of 5.6% by mass were obtained. The values determined for the water-soluble fractions are listed in Table 2.

Example 6

The procedure was analogous to Example 5, except that a solution of 0.15 g of 1-methyl-i-oxo-phospholene (mixture of isomers) in 50 ml of acetone was used. 260 g of coated ammonium polyphosphate having a polycarbodiimide content of 6.9% by weight were obtained. The values determined for the water-soluble fractions are listed in Table 2.

Example 7

The procedure was analogous to Example 5, except that a solution of 0.30 g of 1-methyl-1-oxo-phospholene (mixture of isomers) in 50 ml of acetone was used. 263 g of coated ammonium polyphosphate having a polycarbodiimide content of 7.8% by mass were obtained

 The values determined for the water-soluble fractions are listed in Table 2.

Examples.

The procedure was analogous to Example 5 except that a solution of 0.60 g of i-methyl-1-oxo-phospholene (mixture of isomers) in 50 ml of acetone was used. 272 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.4 mass% were obtained

 The values determined for the water-soluble fractions are listed in Table 2.

Example 9

coated ammonium polyphosphate having a polycarbodiimide content of 8.1% by mass. The values determined for the water-soluble fractions are listed in Table 3.

Example 10

The procedure was analogous to Example 7, except that the reaction time was extended to 3 hours. 276 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.3 mass% were obtained. The values determined for the water-soluble fractions are listed in Table 3.

Example 11

In a heatable enamelled pressure reactor (capacity: 161) with stirrer 2500g ®Exolit 422 were suspended in 4000 ml of acetone; then a solution of 300 g of Caradate 30 in 1000 ml of acetone and a solution of 3.0 g of 1-methyl-1-oxophosphole (mixture of isomers) in 500 ml of acetone were added. Subsequently, the temperature was raised to 8O ⁰ C. This set a pressure of 2.7 bar. After stirring for 1 hour, it was cooled to room temperature and filtered. The resulting filter cake was dried at 100 ° C in a stream of nitrogen. 2850 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.5% by mass were obtained. The values determined for the water-soluble fractions are listed in Table 3.

Example 12

The procedure was analogous to Example 11, except that the reaction time was extended to 2 hours. There were obtained 2800 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.3 mass%. The values determined for the water-soluble fractions are listed in Table 3.

Example 13

It would proceed as in Example 11 except that the reaction temperature was raised to 100 ⁰ C. This resulted in a pressure of 3.8 bar. There were 2 820 g of coated ammonium polyphosphate with a Polycarbodiimidanteil of 8.0 Ma .-%

receive.

The values determined for the water-soluble fractions are listed in Table 3.

Example 14,

The procedure was analogous to Example 5, except that a solution of 1.20 g of 2-methyl-2-oxo-1,2-oxaphospholane in 50 ml of acetone was used. The reaction time was extended to 4 hours. 265 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.2% by mass were obtained

 The values determined for the water-soluble fractions are listed in Table 4. ;

Example 15 '

The procedure was analogous to Example 5, except that a solution of 2.40 g of 2-methyl-2-oxo-1,2-oxaphospholane in 50 ml of acetone was used. The reaction time was extended to 4 hours. There were obtained 270 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.multidot.Ma .-%

 The values determined for the water-soluble fractions are listed in Table 4.

Example 16,

The procedure was analogous to Example 5, except that a solution of 1.20 g of 2-methyl-2,5-dioxo-1-oxa-2-phospholane in 50 ml of acetone was used. The reaction time was extended to 4 hours. 250 g of coated ammonium polyphosphate having a polycarbodiimide content of 8.3 mass% were obtained. , '

The values determined for the water-soluble fractions are listed in Table 4.

Example 17

In a heatable enameled stirred reactor (capacity: 300 l) 60 kg of ®Exolit 422 were suspended in 100 l of acetone; then a solution of 7.2kg® Caradate 30 in 181 acetone and a solution of 144g of 1-methyl-oxo-phospholene (isomeric mixture) (2% based on ®Caradate 30) in 21% acetone were added. Subsequently, the suspension was heated to boiling and kept at this temperature for 3 hours. It was then cooled to room temperature and filtered; the resulting filter cake was dried at 100 ⁰ C in a stream of nitrogen. 64.5 kg of coated ammonium polyphosphate having a polycarbodiimide content of 8.8% by mass were obtained. The water-soluble contents were 0.1% at 25 ° C and 0.6% at 60 ° C. Compared to the uncoated ®Exolit 422 this means a reduction of the water-soluble components by 99% each. Table 5 gives the values of the thermogravimetric analysis.

TABLE 1

product Content of polycarbodiimide (%) at 25 ⁰ C Water soluble content (%) Change at 60 ⁰ C (%) 11.3 Change (%) example 1 3.9 1.0 -88 2.9 -82 Example 2 8.8 0.8 -90 3.6 ^ 95 Example 3 12.1 0.8 -90 13.6 -94 Example 4 15.2 2.0 -76 -78 ·

«Exolit 422 ¹¹

8.2

TABLE 2

Product (catalyst content of poly-water-soluble fractions (%)

concentration 1) carbodiimide at 25 X change at 60 ⁰ C change

Example 5 0.1 5.6 1.8 -78 26 -58 Examples 0.5 6.9 1.0 -88 19 -69 Example 7. 1.0 7.8 0.8 -90 5.9 -91 Examples 2.0 & 4 0.4 -95 1.7 -97 ®Exolit 8.2 62 422 ² '

1) These data refer to the ratio of carbodiimidization catalyst to the amount of polyisocyanate.

2) For comparison, the values for uncoated merchandise "(®Exolit 422j Höchst Aktiengesellschaft, Frankfurt am Main) are listed.

TABLE 3

product

Content of polycarbodiimide

Reaction time (hours)

Reaction temperature ( ⁰ C!

Water-soluble proportions (%) at 25 ⁰ C at 60 ⁰ C.

Example 7 7.8 Example 9 8.1 Example 10 8.3 Example 11 8.5 Example 12 8.3 Example 13 8.0

1 2 3 1 2 1

56 0.80 5.9 56 0.35 1.3 56 0.20 1.1 80 0.17 1.0 80 0.12 0.9 100 0.76 3.1

TABLE 4

product

catalyst

Catalyst concentration 1} (%)

reaction

Time

(Hours.)

Content of poly

carbodiimide

water-soluble

shares

at 25 ⁰ C at 60 X

Example 9 Example 14 Example 15 Example 16

1-methyl-i-oxo-

phospholene

2-methyl-2-oxo-

1,2-oxaphospholane

2-methyl-2-oxo-

1,2-oxaphospholane

2-methyl-2,5-

dioxo-1-oxa-2 ~

phospholane

8.1 8.2 8.3 8.3

0.35

0.7 0.8

1) ®Exolit456, Höchst. Aktiengesellschaft, Frankfurt (Main) It is a melamine-formaldehyde resin coated ®Exolit 422.

1.3 8.1 5.9 18.3

1) These data refer to the ratio of carbodiimidization catalyst to the amount of polyisocyanate

TABLE 5

product coating 300X Weight loss (%) at a temperature of 350X 400X 450X 500X 5.5 8.6 12.5 55O ⁰ C Example 17 (according to the invention) 8.8% polycarbodiimide 0 3.1 17.0 18.4 20.6 18.8 ®Exolit456 ¹⁾ 9.4% melamine-formaldehyde resin 1.1 8.9 24.9

The values from Tables 1 ^ 4 show that with the aid of the modification center according to the invention! the content of water-soluble fractions can be considerably reduced (by 25% by up to 99%, by 6% by up to 99%). The values in Table 5 show that coating with polycarbodiimide results in a modified ammonium polyphosphate with significantly higher thermostability.

Claims (6)

Entitlement to the invention: 1. Flame retardant based on free-flowing, powdered ammonium polyphosphate of the general formula H (n - ml + in which η is an integer having an average value of about 20 to 800 and the ratio of m to Π is about 1, characterized by being off a) about 75 to 99.5Ma .-% ammonium polyphosphate and b) about 0.5 to 25% by mass of a reaction product of a polyisocyanate with a carbodiimidization catalyst, wherein the polycarbodiimide envelops the individual ammonium polyphosphate particles. 2. Mittelach point!, Characterized in that it has an average particle size of about 0.01 to 0.1 mm. 3. Means according to item 1 or 2, characterized in thatthe whole number is between 450 and 800. ' 4. Composition according to item 1 to 3, characterized in that the proportion of the polycarbodiimide is 2 to about 15 wt .-%. 5. Composition according to item 1 to 4, characterized in that the polycarbodiimide is a reaction product which is formed by a catalyzed polycondensation of polyisocyanate. Process for the preparation of a fire protection agent according to one of the preceding points, characterized in that a suspension consisting of a diluent and of free-flowing, powdery ammonium polyphosphate of the general formula