JPS61236812A - Production of flame-retardant urethane foam - Google Patents

Abstract

PURPOSE:To obtain an urethane foam of persistent high flame retardancy with no need of halogen, by using a polyol component incorporated with phosphorus- contg. polyol, foam stabilizer comprising a combination of high-molecular weight silicone with low-molecular weight silicone and phosphoric ester. CONSTITUTION:A composition comprising (A) as a polyol component, a mixed polyol made up of polyether polyol (e.g., trifunctional polyoxypropylene ether polyol) and phosphorus-contg. polyol (pref. with a phosphorus content 1.9-13%, OH-value 56-510), (B) as an additive, a phosphoric ester (e.g., trimethyl phosphate) and (C) as a foam stabilizer, a combination of low-molecular weight silicone and high-molecular weight silicone is agitated together with (D) a catalyst, (E) foaming agent and (F) isocyanate compound followed by expansion to obtain the objective foam.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is applicable to vehicles, furniture, and other various industrial materials.
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The present invention relates to a method for producing a flame-retardant urethane foam suitable for use as heat insulating materials, cushion fan materials, and the like.

(Prior art) ゛Conventional methods for imparting flame retardancy to urethane foam include ■ Addition of phosphorus-halogen compounds; ■ Combination of halogen-containing compounds and metal oxides such as antimony dioxide and zinc oxide (
(Japanese Patent Publication No. 47-21591) ■ Addition of an inorganic compound having water of crystallization such as aluminum oxide or borax is well known.

However, method (2) has the disadvantage that the low molecular weight phosphorus-halogen compound exists only as a plasticizer in the polymerized polyurethane foam, and therefore it decomposes and evaporates after long-term use, reducing the flammability. Furthermore, when heat welding it to synthetic resins or fabrics for automobile interior materials, a large amount of halide decomposes and volatilizes, resulting in a deterioration of the working environment due to odor and smoke. Furthermore, depending on the type of phosphorus halogen compound, it may reduce the catalytic ability of the urethanization reaction catalyst, so there are restrictions on the amount used, so special care must be taken in selection.

Method (2) is widely used in Japan for cushioning as there is no change in flame retardancy over time, but since it uses halogen compounds, it is unavoidable that the working environment during heat welding will deteriorate, and the heat weldability is particularly high. However, it is unsuitable for the frame lamination method and produces a foam with a hard texture, which has many limitations in terms of use.

Method (2) is the same as method (2) because the flame retardant performance of the crystalline water inorganic alone is low, so if a high degree of flame retardancy is required for automobiles, furniture, etc., it is necessary to use a halogen compound in combination. The drawbacks were unavoidable.

(Problems to be Solved by the Invention) The present invention overcomes all of the drawbacks of the above-mentioned prior art, can be used for a wide range of applications such as frame laminates, cushions, and heat insulation, and meets the US automobile safety standards. The purpose of the present invention is to provide a method for manufacturing urethane foam that has excellent flame retardancy that complies with FMVSS Section 302, which is the flame retardant standard.

(Means for solving problems) As a means of making urethane foam flame retardant.

During phosphor firing, a heavy and non-flammable gas such as a halogen is generated, which covers the ignited foam and blocks contact with oxygen in the air, creating a so-called suffocating effect. Either include a compound that lowers the combustion temperature by emitting crystal water during combustion, such as a compound with
A combination of these methods is common, and all of the above-mentioned prior art techniques are based on such means. In this case, the contribution to flame retardancy is that the suffocating effect of halogen gas is extremely large, and if halogen is omitted, it is extremely difficult to stably obtain a flame retardant foam that satisfies the standards of FMVSS Section 302. Met.

As a result of extensive research into halogen-free flame retardant means from all angles, the inventors of the present application have found that urethane foam is a multifoamed material, and in the case of soft urethane foam in particular, many of the cell structures are interconnected. However, there is a tendency for the air contained within the bubbles of the foam to easily move to the combustion site of the foam.

It was discovered that the combination of increasing the closed cell content and minimizing air movement is an extremely effective means to stably exhibit excellent flame retardancy, while flexible urethane foam Increasing the closed cell content of
We have succeeded in solving the paradoxical phenomenon of shrinkage and failure to obtain a good foam by using a general-purpose high-molecular-weight silicone foam stabilizer together with a low-molecular-weight silicone foam stabilizer in a specific range. It was completed.

The mixed polyol used in this application includes 85 to 98.5% of polyether polyol, such as trifunctional polyoxypropylene ether polyol or polyoxyethylene propylene ether polyol, and 1.5 to 15% of phosphorus-containing polyol. A mixture of phosphorus-containing polyols with a phosphorus content of 1.9 to 13% and an OH value of 56 to 5.
A range of 1o is preferred. If the mixing ratio of the phosphorus-containing polyol is less than 1.5%, the flame retardant effect will be poor, and if it exceeds 15%, the physical properties of the foam will deteriorate significantly, so it must be avoided, and is preferably in the range of 2 to 8%.

The combined use of a phosphorus-containing polyol is effective not only for simply improving flame retardancy but also for improving high-frequency welding properties and flame lamination properties.

Phosphate esters used as additives include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, tricylenyl phosphate,
The amount of hexaphosphoric acid ester, which can be used alone or in combination with xylene triyl diphenyl phosphate, cresyl diphenyl phosphate, octyldiphenyl phosphate, triaryl phosphate, etc., is 5 to 45 parts by weight per 100 parts by weight of the mixed polyol. If it is less than 5 parts by weight, even if the proportion of phosphorus-containing polyol in the mixed polyol is increased, a foam with good flame retardancy cannot be obtained, and if it is added in excess of 45 parts by weight, the compression set properties will deteriorate. This results in a significant decrease in the concentration, making it impossible to use it for cuttings.

As the foam stabilizer used in this application, all general-purpose silicone foam stabilizers for flexible urethane foam can be used, but silicone foam stabilizers for flexible urethane foam that have a high molecular weight of around 10,000 are generally used. ing. When this general-purpose silicone foam stabilizer for soft urethane foam is used alone, even if the amount used is varied, the resulting foam shrinks over time after generation, making it difficult to form a normal high-bottomed foam. It is. In order to improve these drawbacks, the combination of a low molecular weight silicone foam stabilizer with a molecular weight of around 1000, which is used only for special foams such as cold cure foams or high elastic foams, has a suitable closed cell ratio. They also discovered that it is possible to stably produce a foam that does not shrink.

The combined amount of this low molecular weight silicone foam stabilizer is in the range of (A)/(B) = 0.7 to 7.0, where general-purpose high molecular weight silicone is (A) and low molecular weight silicone is (B). and (B) is 0 with respect to 100 parts by weight of mixed polyol.
．． It is recommended that the amount be 3 parts by weight or more, preferably in the range of 0.5 to 2.8 parts by weight, in order to achieve a well-balanced foam regulating effect and combustion effect.

Catalysts, blowing agents or other additives used in this application include:
All known ones can be used. That is, as a catalyst, triethylamine, triethylenediamine, N-methylmorpholine, N,N,N',N'tetramethyl1.
Amine catalysts such as 3-butanediamine, organometallic catalysts such as stannath octate, dibutyltin dilaurate, lead naphthenate, and cobalt naphthenate are used alone or in combination.

Also, JI! Typical holding agents include water, freon, methylene chloride, and other inert low-boiling hydrocarbons. In addition, when the amount of phosphorus-containing polyol used is increased, it is desirable to use methylene chloride as a blowing agent to prevent burning.6 Additives include various known plasticizers, inorganic and organic fillers and reinforcing materials.1 Coloring agents. , a non-halogen-based incendiary agent, etc. are added as necessary. Furthermore, known chain extenders such as low molecular weight diols and alkanolamines can also be used in combination, if necessary. In particular, by using a small amount of low molecular weight glycols such as diethylene glycol or 1.4-butanediol, the effect of preventing foam shrinkage can be obtained without lowering the closed cell ratio. In this case, the amount of the low molecular weight glycol used in combination is preferably in the range of 0.1 to 2.5 parts by weight per 100 parts by weight of the mixed polyol.

All known isocyanate compounds used in this application can be used, including general-purpose tolylene diisocyanate,
In addition to diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, metaxylene diisocyanate, polymethylene polyphenylisocyanate, or modified products thereof, etc. are used alone or in combination.

(Example) Examples 1 to 12 Foams were prepared by free foaming in a metal container of 30 x 30 x 30 c+m by a conventional method using 3 times the amount of each of the formulations shown in Table 1. After heating at ℃ for 10 minutes, it was left to mature at room temperature for 24 hours.

The air permeability of the foam was measured using a combustion test of the foam according to the method specified in FMVSS Section 302 and an air flow meter MODEL DA manufactured by Dow Chemical Company.

In addition, in the evaluation of the combustion test, if the fire is extinguished without exceeding the first marked line (marked line placed 38 mm from the end of the specimen), the fire passes regardless of the burning speed, and combustion continues beyond the first marked line. In this case, a haze burning rate of 8 am/min or less was judged to be acceptable. The results were as shown in Table 2.

Comparative Examples 1 to 6 As shown in Table 3, the phosphorus-containing polyols used in the examples,
A foam was prepared in the same manner as in Example except that one or both of the phosphoric acid ester and the low molecular weight silicone were deleted, and a combustion test and an air permeability test were conducted. The results are also listed in Table 3.

(Effect of R-light) ① Even if a phosphorus-containing polyol is used in combination, a certain degree of M combustion effect can be expected, but when used in combination at 2% or more in a general-purpose polyol, Comparative Example 2 and Comparative Example in Table 3.

As shown in 4, when a general-purpose high molecular weight silicone is used alone, the obtained foam shrinks significantly and cannot be put to practical use. In Comparative Example 1, in which the combined use rate of phosphorus-containing polyol was 1%, no shrinkage was observed, but it no longer passed the M fuel standard specified in FMVSS Section 302. However, as shown in each side of the example in Table 1, In addition, the combined use rate of phosphorus-containing polyol was 15
%, foam shrinkage can be prevented by using a low molecular weight silicone foam stabilizer.

Furthermore, if a phosphoric acid ester is used in combination, the synergistic effect of the phosphorous-containing polyol and the phosphoric acid ester will improve flame retardancy.
A flame retardant foam is obtained which can pass the standard of Section S 302 with sufficient reliability.

■If the phosphorus-containing polyol is omitted, even if the amount of phosphoric acid ester is increased to 45 parts by weight, sufficient flame retardance cannot be obtained as shown in Comparative Example 6 in Table 3. The effectiveness of the synergistic effect between the phosphorus-containing polyol and the phosphoric acid ester is recognized.

(2) From the results in Table 2, it can be seen that a foam with a low air permeability, that is, a foam with a high closed cell ratio, tends to have better flame retardant performance. The combination of phosphorus-containing polyol has the effect of increasing the formation of closed cells, but if the amount of phosphorus-containing polyol used in combination is small, low molecular weight diethylene glycol such as diethylene glycol, as shown in Examples 6 and 8 in Table 1, may be used. The closed cell ratio can be increased by using a small amount of glycol. However, if too much of such low molecular weight glycol is added, it will cause shrinkage of the foam, so the weight should be 2.5.

It is preferable that the amount is less than 1.5 parts, and the formulation should be determined in consideration of the amount of the low molecular weight silicone foam stabilizer used to prevent shrinkage.

■The JL flammable urethane foam obtained by the method of the present application not only passes the flame retardant standard of FMVSS Section 302, but also does not cause environmental deterioration due to halogens even when subjected to high frequency welding or flame lamination processing. Since there is little change in flame retardancy over time, it is a technology with extremely high utility value industrially.

Claims (3)

[Claims] (1) When producing urethane foam by mixing and foaming a polyol component with a catalyst, a foam stabilizer, a blowing agent, an additive, and an isocyanate compound, a mixed polyol consisting of a polyether polyol and a phosphorus-containing polyol is used as a polyol component. A method for producing flame-retardant urethane foam, characterized by using a phosphoric acid ester as an additive, and a low molecular weight silicone and a high molecular weight silicone as a foam stabilizer. (2) Mixed polyol is polyether polyol 85~
98.5% and the phosphorus-containing polyol content ranges from 1.5 to 15%. (3) The method for producing a flame-retardant urethane foam according to claim 1, wherein the amount of the phosphoric acid ester added is in the range of 5 to 45 parts by weight per 100 parts by weight of the mixed polyol.