JPH08100040A - Process for producing polyisocyanurate foam containing amide group - Google Patents

Abstract

(57) [Summary] [Objective] To provide a method for producing a polyisocyanurate foam having excellent heat resistance and easy cancer resistance. A NCO group-terminated prepolymer containing an amide group in the molecule obtained by reacting a polyisocyanate and a polycarboxylic acid, a foaming agent, a foam stabilizer and a catalyst are used.
This is a method for producing a polyisocyanurate foam in which the O group terminated prepolymer has an NCO group and a carboxyl group in a functional group equivalent ratio of 3 to 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyisocyanurate foam using an isocyanate group-terminated prepolymer containing an amide group in the molecule. More specifically, it relates to a method for producing a heat insulating foam having improved heat resistance and improved brittleness.

[0002]

2. Description of the Related Art Polyisocyanurate foam has been used as a heat insulating material in the field of construction. Although the isocyanurate group has excellent heat resistance, the polyisocyanurate foam currently on the market has a urethane bond introduced in order to improve brittleness, and therefore its heat resistance is not at a sufficiently satisfactory level.

Therefore, as shown in JP-A-63-165423, attempts have been made to improve the heat resistance by adding a flame retardant. However, addition of a flame retardant generally has drawbacks such as deterioration of physical properties, deterioration with time, increase in foam density, and cost increase. In addition, a similar attempt is made in JP-A-5
No. 3-102994. Here, an organic amine complex is added to urethane-modified isocyanurate to improve surface flame resistance and flame resistance. Further, as isocyanate-reactive compounds other than polyols, epoxy compounds, polycarboxylic acids, acid anhydrides and the like are mentioned, but as a method for improving brittleness, the introduction of urethane bonds is the main one. Therefore, the amount of polyol used was relatively large, and the functional group equivalent ratio in the examples was NCO / OH = 2.

[0004]

In order to improve the heat resistance of polyisocyanurate foam and at the same time improve the brittleness thereof, the introduction of a thermostable bond rather than a urethane bond was investigated, and as a result, an isocyanate group and a carboxyl group were introduced. The amide bond resulting from the reaction with the group has been found to be very effective. However, the polycarboxylic acid used for modifying the foam is usually a solid at room temperature, and has poor compatibility with the main raw material polyisocyanate. Furthermore, 8 is required for the reaction between the isocyanate group and the carboxyl group.
Since a temperature of 0 ° C. or higher is required, it was very difficult to form an amide bond at the same time as forming a foam.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made further diligent studies to obtain a heat resistant foam from the reaction of polyisocyanate and polycarboxylic acid, and as a result, NCO group terminal obtained from polyisocyanate and polycarboxylic acid has been obtained. The inventors have found that an amide bond-containing foam can be obtained by using a prepolymer as a precursor for foam production, and completed the present invention.

That is, the present invention is characterized by using an NCO group-terminated prepolymer containing an amide group in the molecule, a blowing agent, a foam stabilizer and a catalyst, which are synthesized from polyisocyanate and polycarboxylic acid. And a method for producing a polyisocyanurate foam containing an amide group. The present invention also provides that the NCO group-terminated prepolymer is
A method for producing polyisocyanurate foam, which is the prepolymer obtained by reacting an NCO group and a carboxyl group at a functional group equivalent ratio of 3 to 50.

The polyisocyanate used in the present invention is one having at least two NCO groups,
Specifically, polymethylene polyphenyl polyisocyanate, 4,4'-diphenylmethane diisocyanate,
2,4'-diphenylmethane diisocyanate and mixtures thereof, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate and mixtures thereof, hexamethylene diisocyanate and the like.
Modified products of these polyisocyanates such as isocyanurates, alohanates, burettes, and uretonimines can also be used. Furthermore, two or more of these may be used in combination.

The polycarboxylic acid used in the present invention has two or more carboxyl groups in its molecule. Specifically, oxalic acid, malonic acid, succinic acid,
Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, phthalic acid, isophthalic acid, terephthalic acid, di- or tricarboxylic acids obtained by intermolecular self-condensation of unsaturated fatty acids, and the like, These are used alone or in combination of two or more.

N containing an amide group which is a precursor of a polyisosinurate foam containing an amide bond in the molecule
When synthesizing the CO group-terminated prepolymer, the polyisocyanate and the polycarboxylic acid are mixed so that the equivalent ratio of the NCO group and the carboxyl group is 3 to 50. When the equivalent ratio is 3 or less, the obtained prepolymer has a very high viscosity. On the other hand, when the equivalent ratio is 50 or more, the foam becomes brittle and cannot be used practically. Preferably, they are mixed in an equivalent ratio of 5 to 30.

The NCO group-terminated prepolymer of the present invention containing an amide group can be obtained by mixing polycarboxylic acid and polyisocyanate in the above equivalent ratio and then reacting them at 80 to 100 ° C. for 2 to 4 hours. . Furthermore, polyisocyanate and polycarboxylic acid are uniformly mixed in the above ratio using a solvent capable of dissolving polycarboxylic acid, such as tetrahydrofuran, as a compatibilizing agent, and the mixture is mixed at 60 to 70 ° C for 1 to 3 ° C.
After reacting for a period of time, the compatibilizer is distilled off to more easily obtain the prepolymer.

Examples of the foam stabilizers used in the present invention include silicone foam stabilizers used in the production of polyurethane foams. The general structure of this silicon-based foam stabilizer is a polydimethylsiloxane / polyalkylene oxide copolymer, and a commercially available product is D from Corning Dow Corning.
C-193, DC-197 and the like.

As the foaming agent used in the present invention, those usually used in the production of polyurethane foam, polyisocyanurate foam, etc. can be used.
Specifically, 1,1,1,2-tetrafluoroethane,
1,1-dichloro-1-fluoroethane, 1-chloro-
1,1-difluoroethane, 2,2-dichloro-1,1,
Aliphatic hydrocarbon in which a part of hydrogen is halogen-substituted such as 1-trifluoroethane and trifluoroethane, or an organic solvent such as pentane and cyclopentane, and NC
Water that releases carbon dioxide upon reaction with O groups can also be used. Preferred examples of the foaming agent include hydrochlorofluorocarbon or a combination of hydrochlorofluorocarbon and water.

The catalyst used in the present invention may be an NCO group cyclization trimerization catalyst which is generally commercially available. Specifically, alkali metal salts of carboxylic acids such as potassium acetate and sodium acetate, triethylamine, triethylenediamine, 1,3,5-tris (dimethylaminopropyl) -s-hexahydrotriazine, 2,4,6-tris. Examples thereof include tertiary amine catalysts such as (dimethylaminomethyl) phenol, 1,8-diazabicyclo [5,4,0] undecene-7, and quaternary ammonium salts composed of carboxylic acid and tertiary amine.

[0014]

According to the present invention, an epoch-making heat insulating foam having excellent heat resistance and easy cancer resistance (Tumbling Friability due to contact or friction) is produced by a simple and inexpensive method. You can

[0015]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention. Unless otherwise specified, “parts” and “%” in the examples are “parts by weight”.
And "% by weight" are shown.

[Synthesis of Prepolymer ] Synthesis of Prepolymer (1) 11 parts of adipic acid was dissolved in 50 parts of tetrahydrofuran, and polymethylene polyphenyl polyisocyanate (Millionate MR-300, manufactured by Nippon Polyurethane Industry Co., Ltd., MR-300. 100 parts (equivalent ratio =
5) was added and the mixture was reacted at 60 ° C. for 1 hour, and then tetrahydrofuran was distilled off to obtain a prepolymer (1). The appearance was a viscous liquid, and the NCO content was 24.0%. Synthesis of Prepolymer (2) 6 parts of adipic acid was dissolved in 30 parts of tetrahydrofuran, and 100 parts of MR-300 (equivalent ratio = 10) was added to the mixture, and 6 parts were added.
After reacting at 0 ° C. for 1 hour, tetrahydrofuran was distilled off to obtain a prepolymer (2). Appearance is a viscous liquid,
The NCO content was 27.3%. Synthesis of prepolymer (3) 3 parts of adipic acid was dissolved in 15 parts of tetrahydrofuran, and 100 parts of MR-300 (equivalent ratio = 20) was added.
After reacting at 0 ° C. for 1 hour, tetrahydrofuran was distilled off to obtain a prepolymer (3). Appearance is a viscous liquid,
The NCO content was 29.3%.

[Production of Polyisocyanurate Foam] Example 1 Prepolymer (1), DC-197 (manufactured by Dow Corning) as a foam stabilizer, HCFC-141b as a foaming agent,
As a catalyst, Toyocat TRC (manufactured by Tosoh) was mixed and used (each raw material was adjusted to 23 ± 1 ° C .; the same as in the following Examples and Comparative Examples). After stirring for 10 seconds, it was allowed to react in an open type at room temperature. As a result, a polyisocyanurate foam was obtained. The formulation and physical properties are shown in Table 1. Example 2 Prepolymer (2), DC-197, HCFC-141
b and Toyocat TRC were mixed, stirred for 10 seconds, then allowed to flow in an open mold and reacted at room temperature to obtain a polyisocyanurate foam. The formulation and physical properties are shown in Table 1. Example 3 Prepolymer (3), DC-197, HCFC-141
b and Toyocat TRC were mixed, stirred for 10 seconds, then allowed to flow in an open mold and reacted at room temperature to obtain a polyisocyanurate foam. The formulation and physical properties are shown in Table 1.

<Physical property test method> The obtained foam was subjected to a flame resistance test (ASTM D 3014), a smoke test (AST
M D2843), Easy cancer test (ASTM C 4
21), and measurement of the closed cell ratio (ASTM D 2856)
It was evaluated by. The flame resistance test was evaluated by the weight residual rate after combustion. In the smoke emission test, the light attenuation rate at 100 seconds after the start of combustion was evaluated.
From 90% to 90%, 60% or less of the density was low. In addition, the easy carcinogenicity test was evaluated by the weight reduction rate after the test.

Comparative Example 1 MR-300 and adipic acid in the same amount as in the prepolymer (1) were mixed, and DC-197, HCFC-141b and Toyocat TRC were added in the same amount as in Example 1 and added.
After stirring for 0 seconds, the mixture was poured into an open type and reacted at room temperature to obtain a polyisocyanurate foam. A foam was obtained, but unreacted adipic acid was present and did not result in a uniform foam. Therefore, the physical properties of the foam were not measured. The formulation and physical properties are shown in Table 2. Comparative Example 2 The same amount of MR-300 as in the prepolymer (1) was mixed with Example 1
Same amount of DC-197, HCFC-141b and To
After adding yocat TRC and stirring for 10 seconds, it was made to flow in an open type and reacted at room temperature to obtain a polyisocyanurate foam. The formulation and physical properties are shown in Table 2. Comparative Example 3 DC-197 in the same amount as in Example 1, 18 parts of HCFC-1
41b and the same amount of Toyocat TRC as in Example 1
And 20 parts of Pluracol TP440 (polyether polyol, manufactured by BASF) as a modifier are mixed with the same amount of MR-300 as the prepolymer (1), stirred for 10 seconds, and then poured into an open type at room temperature. The reaction was performed to obtain a polyisocyanurate foam. The formulation and physical properties are shown in Table 2. Comparative Example 4 DC-197, HCFC-141b and Toyocat TRC, Pluracol TP4 in the amounts shown in Table 2
The prepolymer (3) was added to a mixture of 40 (the addition amount was such that the number of isocyanate groups in the prepolymer was NCO / OH = 2 with respect to the number of hydroxyl groups in Pluracol TP440. After stirring for 10 seconds, The polyisocyanurate foam was obtained by pouring in an open mold and reacting it at room temperature, and its formulation and physical properties are shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2]

As shown in Table 1, in Examples, foams having a good appearance and a closed cell ratio were obtained. All of these were epoch-making heat resistant foams having excellent heat resistance and easy cancer resistance.

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Claims (2)

[Claims] 1. An amide group characterized by using an isocyanate group-terminated prepolymer containing an amide group in a molecule, a foaming agent, a foam stabilizer and a catalyst, which are synthesized from polyisocyanate and polycarboxylic acid. A method for producing a polyisocyanurate foam containing: 2. A method for producing a polyisocyanurate foam, wherein the isocyanate group-terminated prepolymer is the prepolymer obtained by reacting an isocyanate group and a carboxyl group at a functional group equivalent ratio of 3 to 50.