DE1467276C - Hydrated magnesium carbonate - Google Patents

Description

The invention relates to hydrated magnesium carbonate with the composition 4 MgO · 3 CO ₂ · II H ₂ O, which is distinguished from the previously known hydrate 4 MgO · 3 CO ₂ · 4 H ₂ O in that it has its water of hydration and its carbon dioxide when heated releases much more evenly and in larger quantities at lower temperatures. The production of the new hydrated magnesium carbonate is the subject of German patent 1 190 447.

The hydrate 4 MgO · 3 CO ₂ · 4 H ₂ O is already used in the rubber industry as a filler in white and light-colored masses. It is known that the presence of this material in rubber has the effect of improving the mechanical properties of the vulcanizate, especially when high rigidity and high modulus are required.

The same hydrate has also found use in the manufacture of thermal insulation material. For example, as "85 ° / ₀ Magnesia" known preparation contains 85% magnesium and 15% asbestos.

A major disadvantage in the use of conventional magnesium carbonate in other fields, however, was that the compound carbon dioxide at temperatures below about 350 ° C and water can not dispense with, for example, 200 ⁰ C. The known form of hydrated magnesium carbonate of the formula given above is thus a good filler for rubber by improving its mechanical properties and contributing to the production of good thermal insulation materials, but this form is used as a blowing agent for the production of plastic foam or as a heat transfer medium in polymers not very suitable because it _{is unable to give off CO 2} and water at sufficiently low temperatures.

In the polyurethane foam industry there is a need to control the reaction between polyesters and polyisocyanates to control the degree of foaming by adding water at controlled speeds and to control the cell diameter and extent of the foam during the reaction to increase foaming after the completion of the reaction.

It can be seen daftdie production of these foams would be simplified 45 'when a connection stands available, which emits water at a relatively low speed and at a temperature below about 10O ⁰ C to control the foaming rate during the reaction, and the at the same time has the ability to release an inert gas, such as, for example, carbon dioxide, at a controlled rate at a temperature below 20O ⁰ C after the end of the reaction, in order to increase the degree of foaming.

are similar in the vulcanization of synthetic rubber, for example chlorosulfonated Polyethylene, in which vulcanization is catalyzed by small amounts of water, the method of introducing the water and the temperature at which it is made available, determining factors for processing reliability and the nature of the synthetic rubber produced. If, for example, the water is released at a temperature that is too low, this causes it to occur prematurely Vulcanization or scorching, and this water is then not available for acceleration during solidification available for vulcanization. There is therefore a need for a water releasing agent Rubber additive that releases water during solidification at a rate that gives a good dispersion in the solidifying mass and a vulcanized product with improved mechanical properties.

Similar problems are encountered in the manufacture of products made from products modified by carboxyl groups Nitrile rubber occurred.

According to one embodiment of the invention, hydrated magnesium carbonate of the composition 4 MgO · 3 CO ₂ · 11 H ₂ O is used as an additive to the starting material used for the production of plastic foam. It can e.g. B. be added to a mixture of a polyester and a polyisocyanate for the purpose of producing polyurethane foam.

According to another embodiment of the invention, magnesium carbonate of the composition 4 MgO · 3 CO ₂ · 11 H ₂ O is used as a vulcanization accelerator in synthetic rubber mixtures, for example in the vulcanization of chlorosulfonated polyethylene.

According to a further embodiment of the invention, magnesium carbonate of the composition 4 MgO · 3 CO ₂ · 11 H ₂ O is used as a component of thermal insulation materials.

For example

Production of hydrated magnesium carbonate of the composition 4 MgO · 3 CO ₂ · 11 H ₂ O containing polyurethane foam

10 parts by weight of hydrated magnesium carbonate of the formula 4 MgO 3 CO ₂ 11 H ₂ O are mixed with 1000 parts by weight of glycol-adipic acid polyester with a hydroxyl number of 52 and an acid number of 1. The mixture is reacted with 200 parts by weight of naphthylene 1,5-diisocyanate at 130 ^° C. for 30 minutes. As the reaction proceeds, the temperature rises and reaches 150 ^° C. after 30 minutes. During the reaction, foaming takes place to a small extent. If 2000 parts of water are added to the reaction mixture at 135 ° C, ¹ foaming occurs, which quickly leads to the formation of a spongy mass with the following physical properties:

Tensile strength 400 kg / cm ^a

Elongation at break 700%

Permanent deformation 10%

Tear strength 110 kg / cm ²

Load at 300% elongation .. 95

Barcol hardness (935 scale) 90

Elasticity 50

For example, 2

Insulating material containing hydrated magnesium carbonate of the composition 4 MgO · 3 CO ₂ · 11 H _{2 O}

45.4 kg of hydrated magnesium carbonate of the formula 4 MgO · 3 CO ₂ · 11 H ₂ O are added to 90.7 kg of asbestos fibers.

The mixture is intimately mixed with the following substances:

'Diatomaceous earth 22.7 kg

Finely ground granulated in water

Blast furnace slag 90.7 kg

Na ₂ CO ₃ '. · ....... 3.63 kg

The dry mixture is mixed in a vessel with a capacity of 757 l with 2720 kg of water and mixed for 30 minutes at 100 rpm. touched. The slurry is then passed through a Bauer fiberizer which increases its viscosity. The highly viscous slurry is poured into shallow (5 cm deep) dishes and treated with steam for 2 hours at 105 ° C. and 0.7 atm. The spongy material that forms is crushed into pieces about 25 mm in diameter, and these are placed in molds that correspond to the shape of the desired insulator. In the forms of the composition is within 5 Hour at 7 at a rate from 1.27 to 5.08 cm / sec to 25 ° / ₀ compressed its original volume, after which the mold body 8 hours at 4O ⁰ C and 0.0035 kg / cm ² abs. to be dried. .

Immediately after drying, a side of the insulating material with a viscous solution of 20% acetone and 80 ° / ₀ polyvinyl alcohol is coated. The product is 5 hours in a vacuum at 30 ° C and 0.0035 kg / cm * abs. dried.

The final product has to be coated with polyvinyl alcohol the following characteristics:

1. Dry density .. 0.24 g / cm ²

2. Drying shrinkage 0.20 ° / ₀

3. When heated from 170 to 300 ° C gives
the insulating material 0.3 moles of carbon dioxide
per mole of hydrated magnesium carbonate per minute, per 0.252 kcal.

Be i s ρ i e 1 3

Chlorosulfonated polyethylene (molecular weight 12,000, specific resistance = 1 x 10 "Ω x cm) is formed into a tape on the front roller of a roller mixer, and the mixer is operated until the tape is smooth and free of holes MgO · 3 CO ₂ · Il H ₂ O. Each of the other ingredients listed below is added evenly over the rollers and at a uniform rate and incorporated into the mixture,

ίο before the next ingredient is added. To After mixing, the batch is removed from the mixer, weighed as a control, and reinserted into the Mixer introduced. The batch is run six times at a roller spacing of 0; 76 mm and then at passed through the mixer ten times with a roller spacing of 0.2 mm. During the rolling becomes water of 18 ° C passed through the rollers. The batch is then removed from the mixer as a film and takes 3.6 hours later cut into squares and stored at 153 ° C for vulcanized for different periods of time. Standard ASTM shapes for tension test pieces will be used is used for the squares and normal vulcanization procedures are applied.

Using the procedure described above, mix the ingredients listed in Table I:

Table I -

Chlorosulfonated polyethylene .....

Titanium dioxide (white)

Calcium carbonate. ..

Dipentamethylene thiuram tetrasulfide

Parts by weight

100

50-,

50

Magnesium oxide * ................ according to Table II

4 MgO 3 CO _a 11 H ₂ O according to Table II

Pentaerythritol according to Table II

* Average particle size 0.09 μ, bulk weight
specific gravity 3.32.

Hydrogenated chlorosulfonated magnesium carbonate of the composition 4MgO-SCO ₄ -IlH ₂ O containing

Polyethylene compounds

The following processing procedure is used to mix the ingredients of the composition applied.

The effect of different amounts of the invention used hydrated magnesium carbonates on the physical properties of the vulcanized Synthetic rubber mixtures with different vulcanization times can be found in Table II.

Table II

The following ingredients are added to the first four ingredients listed in Table I. The amounts are given in parts per 100 parts of chlorosulfonated polyethylene.

Hydrated magnesium '
carbonate

Pentaerythritol

Magnesium Oxide ........

Minutes reading

/5 minutes

flO minutes

<35 minutes

3.0
5.0

39
17th
21
29

5.0
3.0
5.0

20.0
3.0
5.0

20.0

Mooney vulcanization at 121 ° C

42.
17th
20th
28

45
15th
18th

23

67
14th
19th

20.0
20.0

73
12th
14th

■ vulcanization. time ^;

■ minutes ■ tension, elongation, and hardness

sModule.'300 ° / ₀ ^{, Akg / cm 2} / tensile strength.'Jcg/cm ² . iDehiiung, ° / ₀ ........

Shorer hardness

Eyesight, '^ ₀

! Elongation, 'P / _o

Changes to: Härlepunkte

/ TOShunden / lOO ^ C, ¹⁰ Z ₀ ,,,! Color change (aged)

> 7.5 7.5

^; 30 85.1
176
490

• 97

476.5
! 440

75

-83
j 142
400

98 128Ϊ7

520

fl49; 8 '330

Changes after 96 hours. Aging at 149 ⁹ C on the:; Air in the test tube

-13

-83

10

'5
-81

-Ϊ93

Permanent deformation after 30%

! 15 82 A

■ 75
: 2

-2

# 7 -Hgo

771 Il

All TEests .- (Were ■; according to .the ASTM ^ methods igeiünrt.

tEarbänderupgist, like; fqlgt ^ specified:

> l = <Jce a change,, 2 - weak \ Y yellow, '■■ ·' ■ "■ ^U 3 = wergilben,

.4 —fBrownish.

Claims (1)

Claims:; 1. Hydrated magnesium carbonate of the formula ; 2. Refusal of the connection of the claim style 25 ,, as an addition to the provision of vvqniKwristst ^ ff-, foam serving output. "3. Execution principle according to claims, thereby igekennzeicbjiet, ^ Jdaß; the! hydrated ^ magnesium !, carbonate. in a 'mixture.' with, an iPöJyester liind i3o: .a-PolyisQcyanatry is used 4. Use of the 'connection' of the claim [l as vulcanization accelerators in synthetic rubber compounds. 5. Embodiment according to Claim 4, applied 35; on the-vulcanization of chlorosulfated ipqly-, ethylene. 6. ^ Use.the.yerbinding of the claim :! as components of insulating materials.