WO1995026995A1

WO1995026995A1 - Casting material

Info

Publication number: WO1995026995A1
Application number: PCT/KR1995/000029
Authority: WO
Inventors: Q. Wayne Lee
Original assignee: BOIN MEDICA Co Ltd
Current assignee: BOIN MEDICA Co Ltd
Priority date: 1994-04-04
Filing date: 1995-03-30
Publication date: 1995-10-12
Anticipated expiration: 1996-10-04
Also published as: KR0136832B1

Abstract

A casting material including a polyurethane prepolymer comprising with a polyol and a polyisocyanate, a tertiary amine, and one or more additives selected from the group consisting of acid silica, acid alumina and acid clay has advantages of a rapid curing and a good storage stability.

Description

CASTING MATERIAL
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a casting material, more specifically, to an orthopaedic polyurethane prepolymer casting material having excellent stability, curing property and conformability which is the measure of conforming into a rigid structure after the shape of a body member.

(2) Description of the Related Art
A number of attempts have been made heretofore to provide an orthopaedic casting material. Generally a suitable casting material must meet the following performance requirements.

1. A casting material should have a good X-ray clarity.

2. A casting material should have a good water resistance.

3. A casting material should be hardened in a short time after application.

4. A casting material should not cause the generation of excessive heat during curing.

5. A casting material should be applicable and removable with ease.

6. A casting material should not cause a skin irritation or infection by the growth of microorganisms and damages by the chemicals in the casting material.

7. A casting material should not require a complex apparatus.

8. A casting material should be of light weight so that patients move comfortably.

9. A casting material should have good shelf-life.

10. A casting material should be highly airpermeable.

As one of casting materials which have been developed so far, plaster of Paris casts is used for immobilization of a desired body member which are formed from strengthened scrim material such as gauze impregnated with plaster of paris. Plaster of Paris casts, however, have a number of disadvantages. These disadvantages include that plaster of paris casts are heavy, weaken in contact with water, not air permeable and cause a skin damages by the growth of microorganisms. Also, plaster of Paris casts have a poor
X-ray clarity and poor conformability when applied to the body member which causes insufficient immobilization of the desired body member. As an attempt to solve the problems of the previously mentioned plaster of paris, an art of preparing flexible fabric impregnated with polymer which is capable of being cured by ultraviolet light is disclosed in U. S. Pat.

Nos. 3,241,501 and 3,881,473. However the major disadvantages associated with these casting materials are that they require significantly longer curing times and the use of ultraviolet light lamp in order to cure the casts it needs a complex operating system. Such casts also have a poor X-ray clarity.

More recent attempts to produce substitutes for the above casting material provide the casting material including polyurethane polymer. The casting material is formed from the fabric coated with prepolymers formed by the reaction of an isocyanate and a polyol. The fabric is soaked in water prior to the application to the desired body, in that the water causes the prepolymer to polymerize and form a resulting rigid polymer structure.

Other arts about polyurethane systems are disclosed in
German Publication No. 2,353,212, U. K. Pat. No.

1,578,895 and PCT application No. WO 81/00671. The casting material disclosed in U. K. Pat. No. 1,578,895 employs aminopolyols as catalysts for curing. The casting material disclosed in PCT publication WO 81/00671 employs a dimethylethanolamine (DMEA) or a mixture of DMEA and bis (2-dimethylaminoethyl) ether as catalysts for curing. Even though these polyurethane systems provide rapid hardening of the prepolymers, the presence of these catalysts in the prepolymer systems causes side reactions such as biuret and allophonate formation and some formation of an isocyanate trimer. which to cause a premature hardening of polyurethane resulting in a poor endurance and a poor stability.

Other recent orthopaedic casting materials comprised of a polyurethane cast and a stabilizer which restrains side reactions caused by catalysts are disclosed in U. S. Pat. Nos 4,433,680 and 4,574,793. The casting material disclosed in U. S. Pat. 4,433,680 employs benzoyl chloride as stabilizer, and in U. S. Pat. 4574793 employs methane sulphonic acid. The use of the stabilizer may improve the stability of the casts. The stabilizer, however, causes some disadvantages including premature curing and longer curing time due to the reaction with catalysts.

SUMMARY OF THE INVENTION
The present invention has an object to solve the disadvantages of the above mentioned casting materials by providing the novel casting material which is characterized as the property of water-permeable, rapid hardening, and applicable and removable with ease. The casting material according to the present invention also has a good X-ray clarity, a good water resistance, a good stability, and a good conformability with a desired body member. Additionally the casting material does not cause exotherm during curing and a skin irritation by the growth of microorganisms or the chemicals in the casting material.

The present invention provides a casting material including a polyurethane prepolymer comprising with a polyol and a polyisocyanate, a tertiary amine, and one or more additives selected from the group consisting of acid silica, acid alumina and acid clay
DETAILED DESCRIPTION OF THE INVENTION
The present invention successfully achieves the above mentioned objects by providing a casting material which comprises a polyurethane prepolymer formed with a polyol and a polyisocyanate, a tertiary amine and the additive selected from the group consisting of acid silica, acid alumina and acid clay.

The prepolymer of the present invention can be prepared according to the same process as in the prior art. s
Typical polyisocyanate for use in the polyurethane prepolymer systems includes 2,4-diisocyanate toluene, 2,6-diisocyanate toluene, or the mixtures of the isomers thereof, 4,4-diisocyanate diphenylmethane, 2,2'diisocyanate diphenylmethane, or the mixtures of the isomers of thereof.

The polyol used in the polyurethane prepolymer systems includes lower polyol, polyether polyol, and polyester polyol. The lower polyol has a molecular weight of 105 to 200 such as N-ethyldiethanol, N-methyldipropanol, triethanolamine, or tripropanolamine. The lower polyol reacts with polybasic acid such as adipic acid, phthalic acid and hexahydrophthalic acid to give the polyester polyol. The polyol having molecular weight of 300 to 2000 alkoxylates an initiator including nitrogen to give the polyether polyol. The initiator includs the lower polyol amines having at least two NH bonds such as ethylene diamine, aniline and hexamethylnediamine. A suitable akyleneoxide for preparing the polyether includes epoxide such as ethylene oxide and butylene oxide, tetrahydrofuran, and styrene oxide.

The preferred polyol for use on the casting material of the invention is one or more selected from the group consisting of diols and triols, and the preferred polyisocyanate is a diphenylmethane diisocyanate. The composition of polyol to polyisocyanateis preferably 1: 2 to 15.

The additives acid silica and acid alumina for use in the present invention, have the following structure, and the acid clay is the mixture of the following acid silica and acid alumina. acid silica
EMI6.1
acid alumina
EMI6.2

In the present invention, it is preferred the additive should be present in an amount of 0.1 to 20 percent by weight based on the prepolymer composition.

In the present invention, it is preferred the tertiary amine should be selected from the group consisting of the following compounds (I) to (V).
EMI6.3

EMI7.1

The preferred casting material in the present invention further comprises the stabilizer which is preferably selected from the group consisting of methane sulphonic acid, benzoyl chloride, phosphoric acid and p-TSA (p-toluene sulphonic acid).

Moreover, the preferred casting material of the present invention further comprise the surfactant which is preferably selected from the group consisting of silicon solutions having a molecular weight of 150 to 200,000.

The additive for use in the present invention, that is, an acid alumina, an acid silica, or the mixture of thereof does not cause the following reaction due to a direct exothermic reaction with a tertiary amine as a catalyst, but simply make weak bond such as a hydrogen bond with the tertiary amine as described below. This can achieve useful dual effect of increasing stability and shortening curing time.

1. Salt formation.
EMI8.1

2. hydrogen bond.
EMI8.2

The present invention may be further illustrated by the following non-limiting examples.

Example 1
To 1 liter reaction kettle equipped with a thermometer, a stirrer, a nitrogen blanket, 430.5 g of diisocyanate (143-L from Dow Chemical Co.: NCO equivalents 143.5); 287.0 g of polyetherdiol (P-1010 from BASF: OH equivalents 500); 31.5 g of polyethertriol (
LG-650 from ARCO Co.: OH equivalents 86.3) was charged.

The charge was heated to 80 C with throughly stirring. and then left to be heated to 100 C by the heat emitted during the exodermic reaction and cooled to 80 C. The resulting product from the charge was extracted and percent NCO was measured. The measured percent NCO was 11.8 (the theoretical percent NCO is 11.6). The product, 249.8g was then diluted with the NCO prepolymer (Isonate 240 from Dow Chemical Co.: NCO equivalents 225) while catalyzed by 16.0 g of the compound having the following formula (I). The percent NCO was 13.0, and the equivalent ratio of NCO to OH was 4.06: 1.00.

To the product 8.5 g of acid clay (American Colloid
Co.) was added to obtain the casting material of the present invention.
EMI9.1

Example 2
To obtain the casting material of the present invention, the process described in Example 1 was repeated except that 15.0 g of the catalyst having the following formula (II) was used in place of the catalyst having the formula (I).
EMI9.2

Comparative Example 1
To 1 liter reaction kettle equipped with a thermometer, a stirrer, a nitrogen blanket, 430.5 g of diisocyanate (143-L from Dow Chemical Co.: NCO equivalents 143.5); 287.0 g of polyetherdiol (P-1010 from BASF: OH equivalents 500); 31.5 g of polyethertriol (LG-650 from ARCO Co.: OH equivalents 86.3) was charged. The charge was heated to 80 C with throughly stirring and left to be heated to 100 C by the heat emitted during the exodermic reaction and cooled to 80 C. The resulting product from the charge was extracted and percent NCO was measured. The measured percent NCO was 11.8 (the theoretical percent
NCO is 11.6). 249.8 g of the product was diluted with the NCO prepolymer (225 equivalents of Isonate 240: NCO from Dow Chemical Co) while catalyzed by 16.0 g of the compound having the following formula (I).

The percent
NCO was 13.0, and the equivalent ratio of NCO to OH was 4.06: 1.00.

To the product 0.35 g of MSA (methane sulphonic acid) was added to obtain the casting material.

Comparative Example 2
To obtain the casting material, the process described in Comparative Example 1 was repeated except that 15.0 g of the catalyst having the formula (II) was used in place of the catalyst having the formula (I).

Comparative Example 3
To obtain the casting material, the process described in Comparative example 1 was repeated except that 1.0 g of benzoyl chloride as a stabilizer was used in place of the MSA.

Reference Example 4
To obtain the casting material, the process described in Comparative Example 2 was repeated except that 1.0 g of benzoyl chloride as a stabilizer was used in place of the MSA.

Measurement of curing time
A film having a thickness of 4 mil was laid on a aluminium panel, and further it was immersed into water.

When the whole film thickness was polymerized and solidified, the curing time of the casting material was measured at the very time.

Measurement of surface curing time
The film having a thickness of 4 mil was laid on a aluminium panel, and further it was immersed into water.

When the surface of the film was hardened to reach about a tack free time, the surface curing time of the casting material was measured at the very time.

Measurement of stability
To an aluminium pouch the casting material was charged at a dry box saturated with nitrogen. It was put into an oven preheated to 80 C, stored for 7 days, and slowly cooled overnight to room temperature prior to measuring the viscosity of the casting materials. The viscosity was measured by using the Brookfield viscosimeter.

(Table 1)
surface curing time (min) stability (CPS)
Example 1 2.5 165,000
Example 2 2.5 170,000
Comparative Example 1 2.5 176,000
Comparative Example 2 2.5 184,000
Comparative Example 3 2.0 290,000
Comparative Example 4 2.0 312,000
It is evident from the results shown in Table 1 that the casting materials prepared in the above examples of the present invention have advantages of a rapid curing and a good storage stability relative to the casting material prepared in the above comparative examples.

Claims

WHAT IS CLAIMED IS: 1. A casting material comprising: a polyurethane prepolymer including a polyol and a polyisocyanate; a tertiary amine; and one or additives selected from the group consisting of acid silica, acid alumina, and acid clay.

2. The casting material of claim 1 wherein the polyol is one or more selected from the group consisting of diols and triols.

3. The casting material of claim 1 wherein the polyisocyanate is a diphenylmethane diisocyanate.

4. The casting material of claim 1 wherein the composition ratio of the polyol to the polyisocyanate is 1 : 2 to 15.

5. The casting material of claim 1 wherein the amount of the additives is 0.1 to 2.0 percent by weight based on the prepolymer.

6. The casting material of claim 1 wherein the tertiary amine is selected from the group consisting of the following compound (I) to (V). EMI12.1 EMI13.1

7. The casting material of claim 1 wherein the casting material is further comprising a stabilizer selected from the group consisting of methane sulphonic acid, benzoyl chloride, phosphoric acid, and paratoluene sulphonic acid.

8. The casting material of claim 1 wherein the casting material is further comprising a surfactant.

9. The casting material of claim 8 wherein the surfactant is selected from the group consisting of silicon solutions having a molecular weight of 150 to 200,000.

AMENDED CLAIMS received by the International Bureau on 29 August 1995 (29.08.95) ; original claim 5 cancelled; orignal claim 1 amended ; remaining claims unchanged (3 pages)] 1. A casting material comprising: a polyurethane prepolymer including a polyol and a polyisocyanate ; from 0.1 to 5 percent, by weight of said prepolymer, of a tertiary amine; and from 0.01 to 5 percent, by weight of said prepolymer, of one or more acid moieties selected from the group consisting of acid silica, acid alumina, and acid clay, whereby said acid moieties chemically interact with said tertiary amine to produce salt formers which improves both the rate of the cure and the package stability.

4. The casting material of claim 1 wherein the composition ratio of the polyol to the polyisocyanate is 1: 2 to 15.

5. (cancelled) 6. The casting material of claim 1 wherein the tertiary amine is selected from the group consisting of the following compound (I) to (V). EMI15.1

7. The casting material of claim 1 wherein the casting material is further comprising a stabilizer selected from the group consisting of methane sulphonic acid, benzoyl chloride, phosphoric acid, and para-toluene sulphonic acid.