JPH03174431A - Soft polyurethane foam - Google Patents

Abstract

PURPOSE: To provide a flexible polyurethane foam which is based on methylene diphenyl isocyanate and is nontoxic and suitable for medical applications by mixing a resin phase, comprising a specified prepolymer, with a water phase and allowing a reaction to proceed.

CONSTITUTION: A poly(oxy 2-4C alkylene)diol (A) having not less than 50 wt.% oxyethylene group, an no. average mol.wt. of not less than 2,000, and two hydroxyl equivalents per mol, an isocyanate component (B) contg. diphenylmethane diisocyanate having a plurality of functionalities, and a polymeric poly(oxy 2-4C alkylene) polyol crosslinking agent (C), with an no. average mol.wt. of not less than 500, having 3 to 4 hydroxyl equivalents per mol are allowed to react with one another so that the ratio of the isocyanate equivalent to the whole hydroxy equivalent is (2.5:1) to (3.5:1). The resin phase comprising the resultant prepolymer is mixed with a water phase, and the mixture is allowed to react. Thus, a flexible polyurethane foam based on methylene diphenyl isocyanate is prepd.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to polyurethane prepolymers and the flexible foams that can be produced therefrom when mixed with water.

Flexible polyurethane foams made with TDI (1-j renin diisocyanate) have been produced in length, especially for cushions and pine tresses. However, for medical or personal protection purposes,
For hydrophilic foams used in re-applications, it is desirable to replace TDI in the foam with MDI (methylene diphenyl isocyanate) because TDI has a high vapor pressure and relatively high toxicity. special precautions are required during processing and use. Additionally, TDI-based 7 ohms can be hydrolyzed and weakened during sterilization or storage in humid containers. For example, the hydrophilic foam of TDI Pace was prepared in a steam autoclave for 12
It can be liquefied after several cycles at 0°C. Also, TDI-based hydrophilic foams swell excessively when wetted to more than about 100% by volume.

Typical polyurethane foams are made from MDI. These 7 ohms are rigid or semi-rigid to give the MDI crystallinity. British Patent Ring 874
, 430, a polyisocyanate mixture consisting of a polyether polyol having at least two hydroxyl groups and a diarylmethane diisocyanate and 5 to 10% by weight of a polyisocyanate having a functionality of 2 or more is prepared in the presence of a small amount of water. Flexible polyurethane foam is produced by reaction. A catalyst can be used in any embodiment. These 7 ohms are not hydrophilic and are difficult to transport large amounts of fibers, fillers, disinfectants, or other water-dispersible components into 7 ohms used for medical or personal protection applications. The disadvantage is that it does not absorb enough water. The term hydrophilic as used herein means that the foam product is capable of absorbing 15 to 20 times its weight in water.

A further disadvantage with any catalyst is that undesirable catalyst residues may remain.

No. 4,237,240, by reacting diphenylmethane diisocyanate with a polyester polyol or a mixture of polyester polyols and polyether polyols having a polyester polyol content of at least 60% by weight of the polyol mixture, and a small amount of water. Soft MDI-based foams with high load carrying capacity and high energy absorption capacity have been manufactured. Catalysts are used as indicated in the claims. In addition to these foams having the disadvantage of containing undesirable catalyst residues in the foam similar to those of GB 874.430 mentioned above, they also require the use of more expensive polyester polyols. I need.

In GB 1,209.058, by reacting a polyisocyanate with a polyether polyol comprising at least 10% by weight of a block copolymer of ethylene oxide capped with propylene oxide to provide hydrolytic stability. Flexible hydrophilic polyurethane foams can be produced. This process requires the use of at least one divalent tin salt of a fatty acid and/or at least one tertiary amine as catalyst. Although the foam products produced in this way are hydrophilic, they have the disadvantage that they not only absorb only small amounts of water, but also require the use of block copolymers. Moreover, there is no indication of the use of MDI, which is hydrophobic, to produce a hydrophilic foam product;
The resulting foam will then contain undesirable catalyst residues.

It is an object of the present invention to provide improved flexible polyurethane foams made from prepolymers containing MDI only as an isocyanate source.

It is an object of the present invention to provide improved flexible polyurethane foams that may contain additional amounts of fiber, filler, disinfectant, or other water-dispersible components.

A further object is to produce a soft hydrophilic foam of white color for use in medical health care applications.

Furthermore, it can be stored indefinitely and used as a carrier for water-dispersible ingredients, only as a source of isocyanate which will also yield a hydrophilic foam product when mixed with approximately equal amounts of water. The objective is to produce polyurethane prepolymers having MDI and its derivatives of

Furthermore, it is an object to produce polyurethane prepolymers having MDI and its derivatives only as isocyanate source, which have viscosity stability over time.

It is also an object to produce a polyurethane prepolymer having up to 50% by weight of isocyanate and having MDI and its derivatives as the only source of isocyanate which will yield a soft 7 ohm.

These and other objects will become apparent from the description of the invention below.

Water-absorbing flexible foams for medical or personal protection applications can be made from isocyanate-capped prepolymers using MDI derived from isocyanates as the sole isocyanate. This foam can be manufactured in two embodiments. One specific example, hereinafter abbreviated as specific example A, uses a monomeric polyol crosslinking agent, and the other specific example, abbreviated as specific example B, uses a polymeric polyol. In this application,
Of these, a patent is claimed only for Specific Example B, and Specific Example A is described for reference only. In specific example A, Carb manufactured by Un1on Carbide
having a molecular weight of at least about 1100, such as owax;
and at least one poly(oxyC3~) having at least 50% by weight of oxylene groups.

(alkylene) diols, monomeric polyol crosslinkers having 3 or 4 individual hydroxyls per mole, such as trioltrimethylolpropane, and isocyanate products with a functionality of 2.0 or higher. , for example, an Upjohn Polymer having a functionality of approximately 2°l and prepared from a mixture of isocyanates including methylene bis(phenylisocyanate) and derivatives of MDI, hereinafter abbreviated as MDI.
Chemicals l5onatel 43-L
Manufacture 7 ohm from MDI based on.

In example B, at least one diol having a relatively low molecular weight of less than 2000 and having at least 50% by weight, preferably at least 80% by weight of oxyethylene groups, such as Carbowax l O00 from Union Carbide, is used. Poly(oxyC2
~4 alkylene): having 3 or 4 hydroxyl equivalents per mole and at least 50
Polymeric poly(oxyC2~, alkylene) polyol crosslinking agents having a relatively high molecular weight of about 0, such as Triol TEP990, Un1on Carbide
or approximately 900 molecular weight poly(oxyethylene) triol from POLY G72-120, 01in
and a mixture of isocyanates including methylene-bis(phenyl isocyanate), hereafter abbreviated as MDI, and derivatives of MDI. isocyanate products having a functionality of approximately 2.1 or higher, such as Upjohn PolymerChemic having a functionality of approximately 2.1.
The foam is manufactured from MDI based on f5onate l43-L made by Al. The composition produces a white foam that is aesthetically pleasing and desirable for medical and health care applications.

One of the important features of these prepolymer compositions is that I
The amount of isocyanate, such as 5onatel 43-L, is in Example A up to 50% of the weight of the prepolymer;
Typically it may be limited to 38-46% and in Example B to 37-48% of the prepolymer. The required amount of isocyanate component is reduced in Example A as the average molecular weight of the diol component increases, so this molecular weight is greater than 1100. When trimethylolpropane is used as the monomeric crosslinking agent, the preferred diol has a molecular weight of about 1200-1400 and contains at least 80% by weight of oxyethylene groups. The diol used in a preferred embodiment is a mixture of two diols with different molecular weights. For example, one diol can have a molecular weight of 1000 and the other 1450. In Example B, the required amount of isocyanate component is reduced as the average molecular weight of the polymeric polyol crosslinking component increases, so this molecular weight is greater than 500. If C arbowax l O00 with a molecular weight of about 1000 is used as diol, a suitable polymeric polyol crosslinker is P polyG172-120, a triol with a molecular weight of about 1400.

The actual free MDI content can be adjusted higher or lower in the isocyanate-containing product as long as the functionality remains above 2.0. For example, additional pure MDI can be added.

The prepolymer with moderate viscosity and good viscosity stability is a relatively low molecular weight polyether polyol, T5on
It can be prepared using MDI-containing isocyanate biochemicals such as ATE 1 43-L and trimethylolpropane (TMOP) as the monomeric crosslinking agent. However, when this prepolymer is mixed with water, the resulting foam is typically a white, semi-rigid foam that is suitable for use as an abrasive sponge, but for use as a cushion or soft foam. is not suitable for

For example, if the MDI-containing form is
43-L, Carbowaxl OOOs and trimethylolpropane (TMOP) as a crosslinking agent to give strength to the foam. December 1980
See US Patent Application No. 314,537, filed May 26, 1981, which is part of the related patents of US Pat. Since TMOP has such a low equivalent weight of 44.7, the prepolymer requires a large amount of isocyanate component, I5onaLe l43-, to cap all the hydroxy groups.
Requires L. The amount of isocyanate is on the order of 50-55% by weight, which makes the foam relatively stiff and hydrophobic.

In specific example A, poly(oxyC2-4 alkylene)
In MDI-containing systems containing, for example, TMOP as diol and monomeric crosslinker, the isocyanate component is advantageously reduced by increasing the average molecular weight of the poly(oxyC2-4 alkylene) diol component to a molecular weight value of 1100 or higher. It was found that it can be obtained. These diols preferably have at least 80% by weight of ethyleneoxy groups. The resulting soft foam retains its physical properties even when treated with steam for 5 hours at 120° C. in an autoclave, and this foam shows a significant reduction in its swelling properties compared to TDI 7 ohm. T
DI-based hydrophobic foams swell over 100% by volume when wetted, whereas the foams in embodiment A of the invention swell only 30-60% when wetted.

Furthermore, in Example B, it has been found that the isocyanate content in MDI-containing systems using relatively low molecular weight diols with a molecular weight of 2000 or less can be advantageously reduced by increasing the molecular weight of the polyol crosslinker. Instead of using TMOP having a molecular weight of 134, a high molecular weight poly(oxyC2-4 alkylene) triol or tetrol having a molecular weight of about 500 to 2000 is used. A suitable example is PoIy G172-120, a triol with a molecular weight of about 1400. The resulting soft 7 ohm is 120 ohms in the autoclave.
It retains its physical properties when treated with steam for 5 hours at 0.degree. C., and the foam shows a significant reduction in its swelling properties compared to TDI 7 ohm. T.D.
I-based hydrophobic foam has 100% volume when wetted
However, the foam in embodiment B of the invention swells only about 30-75% when wetted.

Both specific examples A and B are I 5 onata l
By reducing the content of isocyanates such as 43-L, the resulting foam is more than 50%
te 143-L content and is pliable and resilient compared to semi-rigid, non-resilient foams. I 5 by increasing the molecular weight of the diol
The required amount of onate l 43-L can be reduced to such an extent that the ratio of isocyanate functionality to hydroxyl functionality (known as the isocyanate index) can be reduced from 3.5/1 to about 3/1;
This amount of change contributes to the flexibility of the foam product. Flexibility is best characterized by the bending modulus, but the tensile modulus, which is more easily obtained at 1% elongation, can be used to roughly classify these forms as soft and supple [1,41 kg/c+n2] or less (7)- E-modulus], strong but supple (1
, 41 to 2.82 kg/cm"), and semi-rigid or rigid (modulus of 2.82 kg/cm or more).

Suitable isocyanates in both Examples A and B, including products with a functionality of 2.0 or higher, include diphenylmethane diisocyanate, abbreviated as MDI, and MDI.
It is a mixture of isocyanates including derivatives of. Commercial products meeting this requirement include I5onate l43, which is prepared by reacting MDI to form a carposiimide and then reacting this material again to form a trifunctional cycloaddition product. There is an L. The mixture of MDI, carposiimide and cycloaddition product are in equilibrium. The mixture of components A and B below constitutes the 143L system.

0CN-R-NGO-) [0CN-R-N-C=N-
R-NCOI The term derivative of diphenylmethane diisocyanate as used herein refers to a product prepared from MDI as a starting material. This includes addition products,
Dimers and dimers will be included. M for this one
Materials such as polymethylene polyphenylisocyanate not made from DI will not be included.

Prepolymer techniques in producing foams require mixing with approximately equal amounts of water. This requires that the prepolymer be hydrophilic and I 5onat
The reason is that at least some poly(oxyethylene) containing diols must be used in producing the prepolymer prepared from el 43-L. Desired viscosity is 25°C for good mixing and foaming with water.
ranges from about 10,000 to 35,000 cp, preferably about 20,000 cp. Both the viscosity and the affinity of the prepolymer are controlled by the proper selection of polyol type and molecular weight. This prepolymer must not thicken too much during storage. After an accelerated storage test of 2 weeks at 80°C, the viscosity was 100.000 cp (25°C).
It was found that storage stability is sufficient if the temperature does not rise above (measured at C).

For a flexible foam to be used in many applications, it must have a tensile strength of at least 1.41 kg/c, about 0.048 to 0.0
It should have a foam density of 96 g/cc and an elongation at break of at least 100%, with higher elongation values being preferred. 200% in a certain example in specific example A
An elongation at break was obtained, while an elongation at break of 250% was obtained in the example in Example B.

The diol used is a poly(oxyC2~, alkylene) diol containing at least 50% by weight of oxyethylene groups. Thus, if the diol includes oxypropylene or oxybutylene or mixtures thereof, a small amount of oxyethylene must also be present. Preferred diols in Example A are those having at least 80% by weight oxyethylene groups.

In some preferred embodiments of embodiment A, the diol is Carbo from Un1on Carbide.
It has been found to be satisfactory to use a mixture of waxiooo and Carbovax l 450, but between 1000 and 2000, preferably 1200-140O
It is also within the scope of this embodiment to use formulations of any of the more preferred poly(oxyethylene) diols having number average molecular weights in the range of .

In these examples, the average molecular weight of all diols will be at least about 1100. Advantageously, the 7 ohms produced by using a blend of approximately equimolar amounts of these two diols have low volume swelling and low density.

It is within the scope of Example A to use any monomeric polyol as a crosslinking agent, but
More preferred are polyol crosslinking agents having 4 or 4 hydroxyls. These include trimethylolpropane, trimethylolethane, glycerol, triethanolamine, pentaerythritol or mixtures of these polyols. Most preferred is trimethylolpropane, TMOP, having the formula:

For Example B, Union Ca as the diol
It has been found that using Carbowax l OOO or Carbowax I450 from rbide is satisfactory in preferred embodiments, but
It is also within the scope of this embodiment to use any poly(oxyethylene) diol having a number average molecular weight in the range of 2000, preferably 1000 to 1500.

Although it is within the scope of Example B to use any polymeric polyol as the crosslinking agent, those having 3 or 4 hydroxyls per mole and at least 500 or a mixture of these polymeric polyols. Most preferred is PoIy G72-120, which is an oxyethylene-capped poly(oxypropylene) triol with a molecular weight of about 1400. The oxyethylene moiety here is presumed to contain a block of oxyethylene units bonded to the center of the polyoxypropylene core. It is also believed that the polyol crosslinker can be constructed from random copolymers of these units.

The 7 ohm density and physical properties of Examples A and B appear to be affected by polyol content.

If it is desired to obtain a stiffer and less rubbery foam with lower density, the amount of polyol is increased. Similarly, if higher density and more elasticity are desired, the amount of polyol is reduced. Practical amounts of polyol crosslinkers with 3 or 4 hydroxyl functionality range from 2 to 35% of the hydroxyl content of the diol and polyol mixture.
% originates from the polyol. The preferred range for a good soft 7 ohm is from 10 to
30% hydroxyl. The polyol in Example B is a polymeric polyol, and generally a relatively small amount of polymeric polyol is used to maintain the fluidity of the prepolymer.

When the amount of polyol crosslinker is expressed in terms of the amount of diol present, the diol and polyol crosslinker are expressed in Example A.
is present in a molar ratio of about 4:1 to 8:1, and in Example B when the amount of polymeric polyol crosslinker is expressed in terms of the larger amount of diol present, the diol and polyol crosslinker are present in a molar ratio of about 30 = 1 to 8:l molar ratio.

In Example A, Carbowax l 000 has an equivalent weight of 500 per hydroxyl group, and
TMOP with a molecular weight of 4 has an equivalent weight of 45 per hydroxyl group. Since r 5onate 143L is used to attach the hydroxyl group, the amount of isocyanate required is very strongly influenced by the amount of TMOP, thus controlling the amount of TMOP relatively carefully.

In example B, if the molecular weight of the polyol is too high, the hydroxyl concentration is very low and it takes a very long time to react the starting materials. On the other hand, if the molecular weight is very low and a low molecular weight diol is used, a large amount of isocyanate is required and a stiff 7 ohm is produced.

In Example B, Carbowax l O00 has an equivalent weight of 500 per hydroxyl group, while Poly G72~ has a molecular weight of 1400.
120 has an equivalent weight of 467 per humanmixyl group. Since I 5onata l 43 L is used to bond with the hydroxyl group, the amount of isocyanate required is
Poly G7
The amount between 2 and 120 is adjusted relatively carefully.

A workable amount in both Examples A and B is an isocyanate index of 2.5 to 3.5, preferably 2.
．． 8 to 3.2, and very good results are obtained at 3.1. Higher ratios result in lower polymer viscosity, lower foam density and less swellability, but are also costly and reduce flexibility and elongation. During the preparation of the prepolymer, one isocyanate group of the polyisocyanate component reacts with one hydroxyl group, and the remaining isocyanate groups remain unreacted. These free isocyanate groups on the prepolymer then react with water to form polyurea bonds,
At the same time, the molecular weight increases, which in turn liberates CO2 to produce a foamed product.

When reacting the components in both Examples A and B to form the prepolymer, it is advantageous to measure the amount of isocyanate by titration after the reaction has run for about 1 hour. Based on this knowledge, titration can determine the additional reaction time needed to reduce the amount of isocyanate to approximately the theoretical amount at which all hydroxyl groups will react with the isocyanate. If the reaction is continued to further reduce the amount of isocyanate, the viscosity of the prepolymer increases, making it more difficult to subsequently mix the prepolymer with water. Excessive reaction of the prepolymer components also causes an increase in the 7 ohm density as well as a decrease in the water absorption properties of the resulting foam.

The surfactant is chosen to obtain a foam with the correct cell size, shape, and good appearance without crushing or splitting. Surfactants known to be useful in polyurethane foams can be used here. Examples of suitable surfactants include block copolymers of oxyethylene and oxypropylene, such as Wy
andotte.

Michigan's B A S F wyandot
P 1uronic P o manufactured by Te COrp.
There is lyol surfactant. A suitable surfactant is P r
uronic L-62.

A preferred method in making polyurethane foam is to add about the same amount of aqueous suspension to the prepolymer and then mix the two together. The composition of this aqueous suspension can also be expressed based on 100 parts of prepolymer resin. Thus, 100 parts of water per 100 parts of resin is expressed as 1 oophr of water. The quantity ratio of prepolymer mixture to aqueous suspension can vary within a wide range. However, if the amount of aqueous suspension is too large, the resulting 7 ohm strength will be reduced. On the other hand, if the amount of aqueous suspension is reduced too much, it will not be possible to add enough fiber and filler fed through this aqueous suspension.

A preferred method of foaming the prepolymer involves the addition of an aqueous suspension, such as P 1uronic L-62 surfactant.
% solution as well as the prepolymer to a temperature of approximately 35°C. These were poured or pumped together in a ratio of about 100 parts by weight of aqueous suspension to about 80 parts by weight of prepolymer and immediately attached to a mechanical stirrer, e.g. a drill motor. Feather (bl)
ade) for up to 30 seconds. During this time, complete mixing occurs, but not enough to cause a chemical reaction.

This mixture is immediately poured into a mold where it is allowed to heat up and harden the foam product.

Fibers can be added to the aqueous phase for insert into the foam composition to provide additional structural rigidity.

Polyester fibers are particularly advantageous and can be chopped to about 1.27 cm or less. For aqueous suspensions, the fibers can be added in various amounts, but these are around 10% by weight.
It is preferable not to configure the above, since larger amounts make it difficult to pump the suspension.

A polymeric suspending agent or thickening agent can also be added to maintain dual functionality. Firstly, it prevents water from flowing out of the fibers and retains the suspended components so that the fibers do not float.

Second, this thickening agent acts as a wetting agent for the fibers,
This ensures that they do not get tangled, dehydrated, or crushed as they pass through the mixing pump.

Examples of thickening agents include Polyox WS R, Nat
roso, X anthan gum, and Dow's 5e
There is a polyacrylamide having a molecular weight of about 100,000, such as paran AP 30.

Suitable suspending or thickening agents include B, F, Goo
Car manufactured by drich Chemical Co.
bopol resins, such as Carbopol 934,
(arbopol 940 and especially Carbopol
' There is 941. Since Carboport # fat is an acrylic acid polymer with acid pillar moieties, neutralizing agents such as sodium hydroxide or ammonium can be added. Carbop ammonium hydroxide as a neutralizing agent
It is advantageous to increase the viscosity of the aqueous phase when added to the ol. Also, since ammonium hydroxide is less expensive than Carbopol, more economical compositions can be produced with similar thickening properties and less Carbopol being used.

Depending on any fibers, fillers, disinfectants, pigments, thickeners, or other water-soluble or water-dispersible ingredients that may be included,
The best surfactants are highly hydrophobic silicone types,
Very hydrophilic types, such as L-520 (Union Carbide) or other silicone surfactants;
For example, Brij-58 (ICI-America) or other Brij%Spans, or Tween product production from ICI can be varied. - For fishing applications, non-ionic surfactants, e.g. P 1
uronics, especially L-62, L-72, L-92,
P-75 or P-85 (BASF-Wyando
tte) is preferred. The use of these surfactants is well known to those familiar with the composition of polyurethane foam products.

A water adsorption test is performed by cutting a 7 ohm sample into a rectangle with a size of 2.54 x 7.62 x l 2.70 cm.

Submerge the item in water and hold the item until no more water drops drip. The ratio of wet weight to dry weight is the water adsorption rate.

Although the basic features of the present invention have been shown, the following Reference Examples 1 to 4
is shown to explain a special example of Example A, and Examples 1 to 5 are shown to explain special examples of Example B.

Reference example 1 Carbowax l 000 (174g, 0.
174 mol), Carbowax l 450 (
A mixture of 249 g, 0.172 mol) and trimethylolpropane (6.1 g, 0.045 mol) was heated to 2 Tor
It was dried by heating at 70° C. for 2 hours under reduced pressure of r. Add I5 to this dry and degassed polyol mixture.
onate-143L365g (Isocyanate 2.
56 equivalents) were added. The temperature was held at 7000°C for 70 minutes to complete the reaction. This product has an isocyanate content of 2.18 meq/g and a temperature of 23°C at 25°C.
It was a pale yellow liquid with a viscosity of 0.00 cp.

After storing the sample at 80 °C for 2 weeks, the product was 25
It thickened only to 40,000 cp at °C. 35°C
80 g of the product heated at
4.1 when stirred with 100 mff of a 2% solution of
A soft, pliable, hydrophilic, 7 ohm material having a density of Bond/cubic foot is produced, the properties of which are summarized in Table 1.

Sandbag prepolymer composition reference example 3 Diol composition Carbowax 1000g CarblooO 1450g Average molecular weight triol compound MOP g Hydroxyl % contributing to reaction 174 83 90 249 357 387 456 1265 1335 1365 14506.1 7.
3 1.6 7.0 16 20 5 20 Molar ratio diol/triol l5onate 143L g Isocyanate index 7.6 6.0 30.0 6.0 365 352 320 337 3.1 3.0 3.4 3.0 Isonanate content milliequivalents/g 2.18 2.07 2.51 1.97 Initial viscosity at 25°C cpX10-' Aging for 2 weeks at 80°0 cpXIO-3 Group 1 Physical properties of the blue foamed product reference Example 1234 Density (g/cc) 0.0660.08
20.0660.088 tensile (kg/Cm)
2.18 1.70 2.67 1.70 elongation%
200 170 130 1701%
Modulus (kg/cm”) 1.13 1.27
2.82 1.20% by volume swelling wet/dry 47
53 32 58 Reference Examples 2-4 These examples illustrate foams obtained using different prepolymer compositions. Its composition is shown in Table 1, and its 7 ohm properties are shown in Table 2.

In Reference Example 2, increasing the average molecular weight of the diol,
The use of a small amount of isocyanate in this case resulted in a 7 ohm with high density and greater capacity for water.

In Reference Example 3, the amount of TMOP crosslinker was reduced and the isocyanate index was increased to 3°4 to maintain strength. However, the ratio of diol to triol is outside the scope of this invention and thus this is a comparative example. A stiff foam was obtained, but since it does not absorb water and becomes wet,
It was not possible to determine the water adsorption ratio.

In Reference Example 4, a single diol, Carbovax
1450 was used with TMOP as crosslinker.

A good flexible hydrophilic foam with high elongation, good water holding capacity and water vapor resistance was obtained.

Example 1 Carbowaxl 000 (412g, 0.41
2 mol) and Poly G176120 (28 g,
A mixture of 0.02 mol) of
It was dried by heating at ℃ for 2 hours. This dries,
Add E 5onate to the degassed polyol mixture.
349 g of 143L (2.45 equivalents of isocyanate) was added. The temperature was maintained at 70° C. for 80 minutes to complete the reaction. The product was a pale yellow liquid with an isocyanate content of 1.96 meq/g and a viscosity of 27,000 cp at 25°C. After storing this sample at 80°C for 2 weeks, the product thickened only to 43.0OOcp at 25°C. 80g of the product heated at 35°C was
P, a nonionic surfactant manufactured by Yandotte.
A 2% solution of Iuronic L-62 (00 mQ) produces a soft, pliable, hydrophilic foam having a density of 3.9 pounds per cubic foot when stirred with 00 mQ, the properties of which are summarized in Table 1. do.

Prepolymer composition reference example 23 Diol composition Carbowax 1000g CarblooO 1450g Average molecular weight triol compound Poly G72-120 438 438 1000 1000 1000 1450 14503
4.5 54.8 Molar ratio diol/triol 1sonate 143L g 20.6 12.0 8.6 14.0 8.5349
392 437 317 392 Isocyanate % by weight Initial viscosity at 25°C cpXlO-3 Aging for 2 weeks at 80°C cpxto-” Part Ⅰ Physical properties of foamed product Reference example 23 Density (g/cc) 0.0620 .05
60.05 Tensile (kg/am”) 1.4
1 1.41 1.41 Elongation% 2
53 195 2181% modulus (kg/cm2)
0.56 0.63 0.70% by volume Swelling wet/dry 49 34 340.09 2.11 21 1.80 2 0.066 2°32 03 1.80 4 Residual strain under pressure % Water adsorption ratio 20 18 18 46 Examples 2-5 These samples illustrate foams obtained using different prepolymer compositions. This composition is
The properties of the foam are shown in Table 2.

In Example 2, the amount of triol was decreased and the isocyanate index was increased instead to produce a product with lower viscosity and lower foam density and swelling factor.

In Example 3, the amounts of triol and isocyanate were further increased while good foam properties were maintained.

In Example 4, the molecular weight of the Carbowax diol was reduced to 1450 while the amount of isocyanate was reduced to only 37% by weight of the total composition while maintaining good foam properties.

In Example 5, Carbowax I 450 was also used, but the isocyanate index was increased from 3.0 to 3.5 to reduce the density of the foam and improve its swelling factor.

Claims (1)

Claims: 1. an aqueous phase and a) a poly(
(oxyC_2_-_4 alkylene) diols, provided that the diols have nominally two hydroxyl equivalents per mole; b) a functionality of 2.0 or higher consisting of a mixture of isocyanates, including diphenylmethane diisocyanate and derivatives of diphenylmethane diisocyanate; and c) a polymeric poly(oxyC_2_-_4 alkylene) polyol crosslinker having 3 or 4 hydroxyl equivalents per mole and having a number average molecular weight of at least 500. , wherein the isocyanate comprises a product consisting of up to 50% by weight of prepolymer, and the polymeric polyol crosslinker is combined with hydroxy equivalents of the total hydroxy equivalents in the diol and polyol. 5~
A resin phase consisting of a prepolymer present to constitute 35 mol % and having a ratio of isocyanate equivalents to total hydroxyl equivalents of 2.5:1 to 3.5:1 is mixed together. , and a flexible polyurethane foam based on methylene diphenyl isocyanate. 2. The nominal number average molecular weight of the poly(oxyC_2_-_4 alkylene) diol is between 600 and 2000,
2. The foam of claim 1, wherein the diol has at least 80% by weight of oxyethylene groups. 3. The polymeric polyol crosslinking agent is poly(oxyethylene) triol with a molecular weight of 900, and oxyethylene capped (c) with a molecular weight of 1400.
2. The foam of claim 1, wherein the foam is selected from the group consisting of: 1.appended) poly(oxypropylene)triol, and mixtures thereof. 4. The foam of claim 3, wherein the polymeric polyol crosslinker comprises blocks of oxyethylene and oxypropylene units. 5. The isocyanate product is a modified diphenylmethane diisocyanate containing a high percentage of pure diphenylmethane diisocyanate and small amounts of carbodiimide and carbodiimide cycloaddition products. form. 6. further comprising a reinforcing fiber of polyester fibers having a length of 1.27 cm or less, and further comprising a thickening agent or suspending agent;
A form according to claim 1. 7. a) poly(oxyC_2-_4 alkylene) diols having at least 50% by weight of oxyethylene groups and a nominal number average molecular weight of at least 2000, b) diphenylmethane diisocyanate, and diphenylmethane diiso a diphenylmethane diisocyanate-containing isocyanate product having a functionality of 2.0 or more consisting of a mixture of isocyanates including derivatives of cineate, and c) having 3 or 4 hydroxyl equivalents per mole; and having a nominal number average molecular weight of at least 500.
A prepolymer consisting of the reaction product of a polyol crosslinker, wherein the isocyanate comprises a product consisting of up to 50% by weight of the prepolymer, wherein the polyol crosslinker comprises a product in which hydroxy equivalents are present in the diol and the prepolymer. 5 to 3 of the total hydroxy equivalents of
is present to constitute 5 mole % and the ratio of isocyanate equivalents to total hydroxyl equivalents is 2.
5:1 to 3.5:1. A prepolymer for use in producing flexible foams. 8. The nominal number average molecular weight of the poly(oxyC_2_-_4 alkylene) diol is between 600 and 2000,
8. A prepolymer according to claim 7, wherein the diol has at least 80% by weight of oxyethylene groups. 9. A claim in which the polymeric polyol crosslinking agent is selected from the group consisting of poly(oxyethylene) triol having a molecular weight of 900, and oxyethylene-capped poly(oxypropylene) triol having a molecular weight of 1400, and mixtures thereof. The prepolymer according to item 7. 10. The prepolymer according to claim 7, wherein the polymeric polyol crosslinking agent comprises blocks of oxyethylene and oxypropylene units. 11. The prepolymer of claim 7, wherein the isocyanate product is a modified diphenylmethane diisocyanate containing high percentages of pure diphenylmethane diisocyanate and small amounts of carbodiimide and carbodiimide cycloaddition products.