DE1769187A1 - Soft and hydrophilic polyurethane foam and process for its manufacture - Google Patents

Description

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sS? ic £ arc / ^ füffer-yJSörner 1769187 . J / LANS-JAARIF Qh

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Munich, the Lö. April 1968

20 ELEKAL, Paris (France)

Soft and hydrophilic polyurethane foam and process for its manufacture

The invention relates to a soft and hydrophilic polyurethane foam.

There are known soft polyurethane foams whose outer appearance reminiscent of natural sponges, which are used in particular in the household and for washing vehicles, etc.. It is known that these soft foams consist of a polyurethane polymer based on polyether or polyester polyol. Depending on the type of polyols used in their production, they can have open or closed cells. The water absorption capacity of the polyurethane foams with open cells is greater than that of the polyurethane foams with closed cells. The polyurethane foams known to date have the disadvantage that their water absorption capacity is inadequate, even if they are foams with

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open calls acts, which is obviously disadvantageous in their use.

The erfindungsgeraäß, made of a polyurethane polymer with open cell existing polyurethane foam on the Based on polyether or polyester polyol, however, has good water absorbency. It is characterized in that it, based on the polyol, between 5 and Fe 35 wt .- '/ b, preferably between 15 and 20 wt .-%, more microcrystalline Has cellulose in powder form, which is uniformly dispersed in the polyurethane pores.

The invention also relates to a method of production of the foam. This method is one with a view to obtaining a hydrophilic one Foam modified embodiment of the known manufacturing method of polyurethane foam, the so-called "iSin-shot procedure" ("procede one-shot"), in which one stage, at room temperature and in the presence of water, at least one fatty acid salt of divalent Tin, at least one tertiary amine and at least one surfactant at least one Can react polyol based on polyether or polyester with at least one organic polyisocyanate.

The inventive method is characterized in that the reaction medium, based on polyol, between

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5 and L55% by weight, preferably between 15 and 20% by weight, microcrystalline cellulose are added, so that a soft and hydrophilic foam is obtained.

The inventive method consists in the starting materials for the production of polyurethane foams by the "one shot process" so much microcrystalline Add cellulose, as necessary, to the water absorption capacity of the foam obtained in this way compared to that of the foams made in the same way but not containing cellulose noticeably improve.

Powdered cellulose is used as microcrystalline cellulose used, the particles of which have a diameter between a few tenths and a few tens of microns, preferably between 0.1 and 100 microns. So one uses, for example, the microcrystalline cellulose, which is known under the name

aVICEL manufactured by the American Viscose Corporation f

The powdery microcrystalline cellulose is introduced into the reaction medium by mixing the mixture Stir powder and other raw materials for the production of the foam vigorously. To achieve better homogeneity of the reaction environment and, consequently, of the foam finally obtained, it is advantageous to

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first to mix the microcrystalline cellulose powder with the polyol and then this consisting of two substances To add the catalysts and surfactant to the mixture; this latter measure is carried out, shortly before all of these substances are reacted with water and polyisocyanate or even at the same time.

In the presence of the microcrystalline cellulose, the manufacturer's position h of the foam under the same conditions as in the production of any cellulose-containing foam. In particular, the time required for foaming is the same as in the absence of cellulose.

The use of microcrystalline cellulose is essential if it is desired to add more than 5% by weight of cellulose, based on the polyol, to the starting materials in the production of polyurethane foams by the "iSin-Schuii process". In fact, all types of cellulose, with the exception of the microcrystalline, contain amorphous parts, the presence of which gives the reaction mixture an excessive viscosity as a result of swelling and prevents the formation of a foam having the desired physical properties if the amount of cellulose added is more than 5% by weight, based on the Polyol. Incidentally, adding an amount of cellulose below this latter value is not enough to make the polyurethane

109843/1738 " ^b "

Foams the desired absorbency properties to rent.

Now, however, up to 35% by weight of microcrystalline cellulose can be added to the reaction medium without the viscosity increasing too much to allow the formation of a foam having the desired physical properties. Due to the addition of a considerable amount of cellulose, which is known to be a substance with very high water % absorbency, polyurethane foams are obtained with excellent absorbency.

The same polyols based on polyester or polyether can be used as in the case of the soft polyurethane foams produced in a known manner. Suitably, however, to use the Poiyole on Polyätherbaäs if one wants to obtain a foam, the mechanical strength and hydrolysis resistance are as good as possible g.

As is known, ^If is understood to mean polyols based on polyester ¹ · polyalcohols with at least one ester bond, which result from the reaction of at least one polyalcohol with at least one organic polyacid, in particular an aliphatic polyacid. The polyalcohol used is generally diols, especially ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol, dipropylene glycol,

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1,3-butanediol, 1,4-butanediol or more than two hydroxyl groups containing potencies, e.g., glycerin, sorbitol, pentaerythritol and hexahydroxycyclohexane.

"Polyether-based polyols" are understood as meaning polyalcohols with at least one ether oxide bond. The polyether-based polyols commonly used are e.g. Diols, in particular polypropylene glycol, triols or polyols alcohols with more than three functional hydroxyl groups obtained by adding propylene oxide molecules or ethylene oxide molecules and propylene oxide to form compounds containing active hydrogen atoms, e.g., polyalcohols or polyamines. The names by which the polyether-based polyols are known in the trade are very diverse (Niax, Voranol, Üesmophen etc.).

The organic polyisocyanates to be used are the. those that are used in the known manufacturing processes for soft polyurethane foams, in particular the following polyisocyanates: 2,2- and 2,6-tolylene diisocyanate, 1,4- and 1,5- naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, dimeric 2,4-tolylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4 * ^ "- triphenylmethane triisocyanate or Polymethylene polyphenyl isocyanate containing three to five benzene nuclei. A device made from these polyisocyanates can also be used.

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example 1

By stirring with the aid of a stirrer rotating at 3500 rpm an intimate mixture of the following substances is produced:

Niax 14-1ϋ (primary polyether triol,

whose OH value is 40, produced

by Union Carbide) 100 parts

Microcrystalline cellulose powder

(Brand AVICEL ₁ Manufactured by

American Viscose Corporation) 10 parts

Soliconöl SF lOöü (General Electric) 2 parts

Catalyst A ₁ (Union Carbide) 0.2 parts

Stannioctoate 0.2 parts

First you add the polyol, then the microcrystalline cellulose into the container in which the mixing takes place. The temperature of the added substances at the time of addition is 22 ° C.

To maintain a homogeneous dispersion of the micro ~ f

crystalline cellulose required stirring time is 15 seconds. Thereafter, 3.5 parts of water and 43.5 parts of a mixture of 2,4- and 2,6-tolyl diisocyanate which consists of 80 % of the former of these isomers and are added quickly one after the other and without interrupting the stirring of the "mixture 20 mole percent of the second, this amount corresponding to a "TDI" of 105.

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The "TDI value" is a penalty for that multiplied by 100 Ratio of the amount of tolyl diisocyanate reacted to the stoichiometric amount, i.e. to the amount that is necessary for the number of isocyanate groups is equal to the sum of the number of alcohol groups in the polyol + half of the water molecules. It should be noted that When calculating the "TDI value", the alcohol groups of the cellulose are not taken into account, as these groups do not react with the isocyanate groups.

All quantitative data for the substances forming the mixture are given in parts by weight.

After adding the diisocyanate to the reaction medium continue stirring for 5 to 7 seconds, i.e. until the mixture suddenly takes on a creamy appearance. At that moment, you pour the entire mixture very quickly into a cardboard mold lined with paper.

Rapid foaming can be observed, causing the foam to "rise", which quickly fills the entire shape. The time required for complete foaming is about one minute. Then the so formed Foam kept in a drying oven at a temperature of 120 ° C for one hour. The foam thus obtained can easily be cut into blocks of the desired dimensions, which can be used as sponges.

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Example 2

The procedure is the same as in Example 1, however with IG parts of microcrystalline cellulose.

Example 3

The procedure is the same as in Example 1, but with 0.1 part of stannous octoate instead of 0.2 part.

Example 4

The procedure is the same as in Example 3, but with 15 parts of microcrystalline cellulose.

Example 5

The procedure is the same as in Example 3, but with 20 parts of microcrystalline cellulose.

Example 6

The procedure is the same as in Example 3, however with 25 parts of microcrystalline cellulose.

Example 7

The procedure is the same as in Example 3, but with 30 parts of microcrystalline cellulose.

Example 8

The procedure is the same as in Example 3, however with 35 parts of microcrystalline cellulose.

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Example 9

The procedure is the same as in Example 2, but instead of Niax 14-16 Desmophen 3600, which is one of Farbenfabriken Bayer, Leverkusen, produced linear polypropylene glycol with a molecular weight of about 2000 and an OH value of 56.

The water absorbency of the foams shown in the above examples is measured by measuring the ^{degree of capillary absorption 11} in the manner described in French patent 1,284,015 (Khdne-Poulenc).

After the improvement in the water absorption capacity of the foams produced by the process according to the invention in comparison to that of the foams produced without the addition of microcrystalline cellulose was found, three comparative foams were produced by following the steps in each of Examples 1, 3 and 9 indicated manner, but without using microcrystalline cellulose.

So is the first of these comparison foams with the after to compare foams produced in Examples 1 and 2, the second with those produced according to Examples 3 to 8 and the third with that produced according to Example 9 Foam.

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The degrees of capillary absorption of the various foams produced according to the examples described above and the comparative foams are from the following Table:

Foam

Degree of capillary absorption

Foam according to example 1 plastic according to example 2, comparative foam 1
Foam according to Example 3 Foam according to Example 4 Foam according to Example 5 Foam according to Example 6 Foam according to Example 7 Foam according to Example 8 Comparative foam 2
Foam according to Example 9, comparative foam 3

85

43.3

75

üü

62

50

43.4

65

35

When comparing the values of the degrees of capillary absorption of the foams produced according to the preceding examples with those of the corresponding comparative foams without cellulose, it becomes apparent that the addition of microcrystalline foams Cellulose according to the process according to the invention to the reaction medium in the production of soft polyurethane foams causes an extraordinary improvement in the water absorbency of these foams.

Claims;

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Claims (4)

Patent claims: 1. Soft and hydrophilic polyurethane foam, consisting of a polyurethane polymer with open cells Polyether or polyester base, characterized that, based on the polyol, it is between 5 and 35% by weight, preferably between 15 and 20% by weight, more microcrystalline Cellilose in the form of a fine, homogeneous in the pores of the Contains polyurethane dispersed powder. 2. Process for the production of a polyurethane foam, in the one-stage, at room temperature and in the presence of water, at least one fatty acid salt of divalent Tin, at least one tertiary amine and at least one surfactant at least one polyol based on polyether or polyester is reacted with at least one organic polyisocyanate, characterized in that the reaction medium, based 109843/1738 on the polyol, between 5 and 35% by weight, preferably between 15 and 20 wt .-%, microcrystalline cellulose are added so that a soft and hydrophilic Foam received. 3. The method according to claim 2, characterized in that the microcrystalline cellulose is added by first the pulverulent ^ cellulose is homogeneously mixed with the polyol and then the surface-active agent, the fatty acid salt i and the tertiary amine before or during the binary mixture obtained the reaction of all these substances with the water and the polyisocyanate are added. 4. The method according to claim 3, characterized in that the diameter of the cellulose powder is between 0.1 and 100 microns. 109843/1738