JPS5857457B2 - rigid polyurethane syntact foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides flame retardant rigid polyurethane syntact foam ('
5yntactic foam).

hollow beads, bubbles or microballoons (m1cro
Compositions containing balloon have been known for many years.

The concept of using these hollow beads in the composition is devised to reduce density and to reduce expensive matrix materials.

However, it has been observed that the reduction in density also leads to a reduction in the structural strength of the product and it is difficult to maintain maximum strength with reduced density.

The use of liquid reactants to produce polyurethanes, both foams and solid products, is well known from the prior art.

It is also well known that flame retardants such as tris(2-chloroethyl) phosphate can be used as flame retardants in polyurethanes.

It is also clear from the prior art that when using such flame retardant materials there are too many disadvantages associated with this low molecular weight material which is widely used in the production of flame retardant polyurethane foams.

The use of solvents or diluents for compositions containing large quantities of microballoons is also known from the prior art.

However, a product that is injectable or castable, has a relatively low density, contains a large amount of microballoons, and can be cast and cured into thick sections that are structurally as strong or stronger than wood. It was not previously known that it was possible to produce rigid polyurethane syntact foams that hardened to a solid state and had flame retardant properties that exceeded prior art rigid polyurethanes.

The present invention relates to flame retardant rigid polyurethane sink foams made from a mixture of microballoons, an organic polyol, a polyisocyanate, a catalyst and a flame retardant that also acts as a flow promoter.

The flame retardant imparts sufficient fluidity to the composition to allow it to be cast into a mold, flows into the mold details and crevices, and ensures that the composition when cured is flame retardant. It also allows it to be structurally strong.

Flexural strength can be improved by adding non-combustible flexible fibers such as glass fibers to the mixture.

The composition cures in large molds to provide a cured product that can replace wood with the added advantage of being flame retardant.

Therefore, the object of the present invention is to be able to cast into a mold,
It is also an object to provide a flame retardant syntact foam that cures to a product that can replace wood and is also flame retardant.

These and other objectives will become more apparent in the detailed discussion below.

The present invention relates to an organic polyol, a polyisocyanate, a microballoon, a catalyst for the reaction of the organic polyol and the polyisocyanate, and tris(
A mixture consisting essentially of a composition obtained by mixing β-chloroethyl) phosphate,
the combination of said organic polyol and polyisocyanate is liquid at 25°C, and there are sufficient microballoons in the mixture to provide a non-castable mixture in the absence of said flame retardant; The amount of said flame retardant is sufficient to provide a castable mixture that flows into the mold cavity to the extent that the mold details are filled, and the cured product obtained from the mixture consists of a rigid polyurethane. Made of syntact foam.

Organic polyols and polyisocyanates that are liquid at 25°C are well known in the prior art.

There is no limitation to the particular polyol or incyanate except that the combination of the two is liquid at 25°C.

Organic polyols can be either polyether or polyester types.

It is also within the scope of this invention to use pre-reacted combinations of organic polyols and polyisocyanates.

However, organic polyols and polyisocyanates are combinations of organic polyols and polyisocyanates that give rigid polyurethanes.

Microballoons can be made from any number of materials known in the art, but are preferably made from glass, which provides optimal physical properties with respect to strength.

The particle size of the microballoons is that commonly found in the prior art.

Catalysts are those commonly used for curing polyurethanes, especially those that catalyze the reaction between organic polyols and polyisocyanates, such as amines and tin catalysts.

Foams with the combined properties of low density, strength, flowability, and flame retardancy are produced by the use of a combination of liquid organic polyols and polyisocyanates, and a sufficient amount to render the resulting mixture non-castable and non-flowable. This results from the use of microballoons and then enough of the above flame retardant to make the mixture castable to the extent that it flows into the cavities of the mold so that the details of the mold are filled.

By using these amounts, the resulting cured rigid polyurethane sink foam is strong, low in density, and flame retardant.

The amounts of each component will depend on the particular organic polyol, polyisocyanate and microballoon used.

These components vary widely in properties and thus the amount of each will vary as well.

The relevant amounts of organic polyol and polyisocyanate are used in prior art stoichiometric amounts.

The mixture can also contain non-combustible flexible fibers with a length of less than 257 nr/L.

These non-combustible flexible fibers improve the flexural strength of the rigid polyurethane sink foam.

A preferred non-combustible flexible fiber is glass fiber.

These non-combustible flexible fibers can be single monofilaments or fibers or multi-filaments referred to herein as bundles.

Fibers can be cut to suitable lengths from longer ropes.

Preferably, the fibers are about 6 inches long. These non-combustible flexible fibers improve the flexural strength of rigid polyurethane syntact foams without interfering with flame retardancy or castability of the mixture.

The amount of non-combustible flexible fibers will vary depending on the particular mixing and molding equipment available, but the amount will reduce the flowability of the mixture to the point where the mixture is no longer suitable for casting into a mold. It should not be such an amount.

It has been found that amounts of 5 to 15% by weight, based on the total weight of the mixture, are suitable for increasing the flexural strength without reducing the ability of the mixture to be cast into molds.

The components are combined in a manner commonly used in the prior art, with the polyisocyanate usually being added last.

Any other method of combining the components can be applied as long as the final mixture can be cast into a mold.

Once all ingredients are mixed, they will cure at room temperature to form a rigid polyurethane syntact foam.

The syntact foams of the present invention are suitable for structural applications such as wood replacements and have the added advantage of being flame retardant.

The following examples are given for illustrative purposes only and are not intended as limitations on the invention, which is properly set forth in the claims.

Example 1 6 parts by weight of a commercial organic polyol, 6 parts by weight of polymethylene polyphenyl diisocyanate, 6 parts by weight of tris(baked-chloroethyl) phosphate, 2.5 parts of glass microballoons, and 1 part by weight of triethylene diamine and diisocyanate. 0.1 mixture of 2 parts by weight of propylene glycol
A mixture of parts by weight was prepared.

The above mixture was prepared by adding the isocyanate component last.

The resulting mixture was a liquid that could be easily cast in a mold and was non-flammable when cured into a rigid polyurethane sink foam.

The mixture was prepared as described above except that the tris(baked chloro-ethyl) phosphate was omitted.

This mixture was a wet powder, uncastable, and burned when cured.

This material has a limiting oxygen index of 17% oxygen (1 part mitin
The mixture containing tris(baked chloro-ethyl) phosphate had an LOI of 80% oxygen.

Example 2 100 parts by weight of commercial organic polyol, 42 parts by weight of glass microballoons, Tris(betachloroethyl)
A mixture of 75 parts by weight of phosphate, 1 part by weight of the catalyst mixture of Example 1, and 100 parts by weight of polymethylene polyphenyl diisocyanate was prepared by adding the incyanate component last.

This mixture was castable and cured at room temperature to yield a rigid polyurethane syntact foam that was nonflammable, ie, no combustion occurred after the flame was removed.

Example 3 (N commercial organic polyol ioo parts by weight, Tris(
5 parts by weight of beta-chloroethyl 9-phosphaide 1F, 35 parts by weight of glass microballoons, 15 parts by weight of silicone surfactant, and 1.0 parts by weight of a mixture of 1 part by weight of 1-helical ethylenediamine and 2 parts by weight of dipropylene glycol. A mixture of parts by weight was prepared.

Adding 100 parts by weight of polymethylene polyphenyl diisocyanate to the mixture and curing the mixture;
This was used as a test sample.

(B) A mixture was prepared as in (4) above, except that 5 parts by weight of chopped glass fiber cord having a length of about 6 mrn was present in the mixture.

A mixture was prepared in the same manner as in (4) above, except that □o parts by weight of chopped glass fiber cord having a length of about 6rIL11L was present in the mixture.

Flexural strength was measured for each cured sample of (4), (B), and (C) using the ASTM-D-790 test method, and the results are shown in the table below in kilopascals (kpa).

Claims (1)

[Claims] 1. A composition obtained by mixing an organic polyol, a polyisocyanate, a microballoon, a catalyst for the reaction between the organic polyol and the polyisocyanate, and tris(β-chloroethyl) phosphate as a flame retardant. A mixture consisting essentially of 25 organic polyols and polyisocyanates.
°C, there is a sufficient amount of microballoons in the mixture to provide a non-castable mixture in the absence of said flame retardant, and the amount of said flame retardant in the mixture is A rigid polyurethane syntact foam consisting of the cured product obtained from the mixture in an amount sufficient to provide a castable mixture that flows to the extent that the mold details are filled. 2. The mixture optionally further contains non-combustible flexible fibers with a length of 251 rL.
Rigid polyurethane syntact foam as described in .