JPH04149227A - Catalyst for producing polyurethane foam and production of flexible polyurethane foam - Google Patents

Abstract

PURPOSE:To obtain the subject catalyst, containing hydroxyethylimidazole and capable of improving working environment, deodorizing flexible polyurethane foams after expansion and improving merchandise value. CONSTITUTION:The objective catalyst containing 1-hydroxyethylimidazole and preferably an organotin compound (preferably stannous octylate). The aforementioned catalyst is used in reacting an isocyanate with a polyol in the presence of a foaming agent and a surfactant to produce polyurethane foams.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a novel catalyst for producing flexible polyurethane foam and flexible polyurethane foam produced using the same, and particularly to improvement of the working environment during production; It is characterized by making the soft urethane foam odorless after foaming and improving its commercial value.

[Conventional technology]

Soft urethane foam is used in a wide range of industries because of its good cushioning properties, air permeability and sound absorption properties due to its oven cell structure, and the ability to create a wide range of specific gravity and cushioning properties by changing formulations.

Light polyurethane slab foam is usually manufactured continuously in the form of a large loaf of bread, and after being cut into the required shape, it is used for various purposes.

Catalysts used in the production of light urethane foam include triethylenediamine, trinotylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, tetramethylhexamethylenediamine, pentamethyldiethylenetriamine, dimethylcyclohexylamine, and dimethylethanolamine. There are amine catalysts such as stannous octoate, and metal catalysts typified by dibutyltin dilaurate.

Among amine catalysts, in soft slab form, N
-Weakly active catalysts such as methylmorpholine, N-ethylmorpholine, triethylamine, etc. are often used to delicately control the polyurethane manufacturing process.

[Problem to be solved by the invention]

However, the weak (low) activity catalysts for producing polyurethane that have been developed so far have various problems.

In other words, N-methylmorpholine and N-ethylmorpholine are easy to volatilize due to their low molecular weight, low boiling point, and high vapor pressure at room temperature, and due to the foul odor of the catalyst itself, they can significantly pollute the working environment and prevent exhaust and ventilation. Such equipment requires a large amount of cost.

Additionally, using trimethylamine, triethylamine, N-methylmorpholine, or N-ethylmorpholine,
When polyurethane is manufactured, the boiling point of these compounds is low, so the vapor pressure is high at room temperature, and even after manufacturing, the product, flexible polyurethane foam, has the disadvantage that it has a pungent odor.

Furthermore, when polyurethane foam is manufactured using these compounds, the urethane catalyst remaining in the product
Other compounds in contact with the polyurethane foam (e.g. p
VC sheets), causing problems such as discoloration and staining, and often resulting in products having no commercial value.

Therefore, various amine compounds with high boiling points and low vapor pressures have been proposed as amine catalysts.

For example, dimethylamino monoether monool shown in Japanese Patent Publication No. 56-9168, Japanese Patent Publication No. 61-46483
N-butylmorpholine, a mixture of N,N-dimethylpiperazine and an alkoxylated alcohol solvent, etc., shown in the above-mentioned No. 1, have been proposed.

However, the dimethylamino monoether monool proposed by the former excessively promotes the reaction between water and isocyanate, that is, the so-called foaming reaction, and is particularly useful for polyurethane foams with excellent physical properties, such as polyester-type low-density foams. In manufacturing, the balance between the foaming reaction and the resinizing reaction is not suitable, resulting in a foam with poor air permeability. It also has the disadvantage of large compression set.

The catalyst mixture proposed by the latter also contains N-butylmorpholine, and although this compound has lower odor than N-methylmorpholine or N-ethylmorpholine, it is not very satisfactory.

Therefore, there has been a need for an amine catalyst with lower odor, higher air permeability, and lower compression set.

[Means to solve the problem]

The present inventors have noticed that a tertiary amine compound having a hydroxyl group reactive with isocyanate has a high boiling point and low vapor pressure due to hydrogen bonding, and is suitable as a urethane catalyst.

As a result of intensive studies to solve the above problems, we found that 1-hydroxyethylimidazole is a low-odor, non-migration type amine catalyst containing a hydroxyl group, and has optimal catalytic activity for urethanization reactions. The present invention was completed based on the discovery that the polyurethane foam can be suitably used in the production of polyurethane foam.

That is, the present invention relates to a catalyst for producing polyurethane foam characterized by containing 1-hydroxyethylimidazole.

The present invention also provides a flexible polyurethane foam characterized in that 1-hydroxyethylimidazole is used as a catalyst in producing the polyurethane foam by reacting an isocyanate and a polyol in the presence of a blowing agent and a surfactant. It provides a method for manufacturing.

Since the catalyst of the present invention has a hydroxyl group that reacts with isocyanate, it reacts with isocyanate during molding of urethane foam, is fixed in the foam, and does not bleed.

In addition, the catalyst of the present invention has a high boiling point, does not emit a bad odor, and is less likely to volatilize than foam. Further, in the urethane production reaction, the competitive reactions of foaming and resin formation are allowed to proceed in a well-balanced manner. As a result, after the polyol or the polyol component containing the auxiliary agent and isocyanate are mixed, the foam has excellent fluidity in the foaming and resin-forming reactions, and in the case of molded products, it is suitable for molding complex shapes. Shows corresponding formability. In addition, in the case of soft slab foam, there is no bad odor when it is cut into the required shape.
This form is suitable for use in furniture, including bedding.

The novel catalyst of the present invention can be synthesized by a known method of adding ethylene oxide to imidazole (see Japanese Patent Publication No. 4013872).

The amount of catalyst used in the present invention is from 0.01 to 100 parts by weight of polyol used for producing polyurethane foam.
The range is preferably 5 parts by weight, particularly preferably 0.1 to 3 parts by weight.
However, by controlling the amount of catalyst added, it is possible to use a value outside this range for the purpose of optimizing the polyurethane foam manufacturing process.

Furthermore, the novel catalyst of the present invention can be used in combination with tertiary amines such as triethylenediamine, which are commonly used as catalysts for polyurethane production, or organometallic compounds such as organotin compounds when producing polyurethane. .

In particular, when used in combination with an organic tin compound, air permeability can be well adjusted due to the open cell structure, making it possible to support various polyurethane foam manufacturing systems.

Among organic tin compounds, stannous octylate is particularly preferred.

The proportion of the organotin compound used relative to 1-hydroxyethylimidazole is not particularly limited, but is preferably 0.05 to 1 part by weight relative to 1 part by weight of 1-hydroxyethylimidazole. A sufficient effect can be obtained by adding a small amount, but if the amount is too small, the effect of improving the reaction rate is difficult to appear.

The components used in the production of the flexible polyurethane foam of the present invention are not particularly limited and can be those commonly used. Further, the amount of the compound may be the same as usual.

Polyols that can be used in the present invention include polyester polyols produced from dibasic acids and polyhydric alcohols, and polyols produced by adding ethylene oxide or propylene oxide to polyhydric alcohols such as glycol, glycerin, pentaerythritol, and trimethylolpropane. There are polyether polyols obtained by
Those having two or more hydroxyl groups per molecule and having a hydroxyl value in the range of 30 to 100 are preferably used.

Isocyanates that can be used in the present invention include aromatic polyisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate), aliphatic polyisocyanates (hexamethylene diisocyanate), cycloaliphatic polyisocyanates (isophorone diisocyanate), and carbodiimide-modified isocyanates, and carbodiimide-modified isocyanates. Mention may be made of terminal isocyanate prepolymers by reaction with hydrogen compounds.

Among these organic isocyanates, aromatic polyisocyanates are preferred.

The blowing agents used in the present invention include water, trichlorofluoromethane, dichlorodifluoromethane, LL, 1.
2-tetrafluoroethane, 2,2 dichloro-i,i,
There are low boiling point compounds such as t-trifluoroethane, 1,1-dichloro-1-fluoroethane, and methylene chloride, which can be used alone or in combination.

As the surfactant used in the present invention, organosilicon surfactants such as organopolysiloxane copolymers, or non-silicon surfactants such as alkylene oxide adducts of alkylphenols are used alone or in combination. I can do it.

In particular, when a polyalkylene oxide methylsiloxane copolymer is used, suitable air permeability can be obtained.

In the present invention, a crosslinking agent or a chain extender may be used if necessary, such as triethanolamine,
Examples include jetanolamine, ethylene glycol, diethylene glycol, butanediol, trimethylolpropane, glycerin, tolylene diamine, xylylene diamine, and the like.

As the method for producing the flexible polyurethane foam of the present invention, any conventional method can be adopted.

As described above, according to the method of the present invention, if 1-hydroxyethylimidazole is blended as a catalyst and flexible polyurethane foam is produced, it is possible to produce flexible polyurethane foam during and after production, which was not possible with conventional methods. It is possible to produce a desirable product that has no odor, improves the working environment, and has no odor from the flexible polyurethane foam product.

〔Example〕

EXAMPLES The present invention will be explained in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Test method) The mixing ratio of raw materials for producing polyurethane was set as shown in Table 1, and foaming of polyurethane foam was carried out according to the usual procedure. That is, a polyester polyol, water, a surfactant, a catalyst, and a polyisocyanate maintained at 40'C were mixed and stirred, and the urethane foam was foamed and cured.

The produced urethane foam was evaluated as follows 1) to 3).

■) Cream Time (CT) and Rise Time (RT)
An upper oven malt measuring 15 cm x 15 cm x 20 cm (height) with a polyethylene film attached to the inside was used. The room temperature at the time of the test was 20°C.

The polyester polyol held at 40°C, water and silicone surfactant are weighed into a polycup and stirred in a lab mixer for 15 seconds. Then, metal catalyst TDI-8
Quickly add 0 and mix again with a lab mixer running at high speed. Cream time (CT) is the time it takes for the mixture to become creamy after pouring the stirred mixture into the mold.
and the rise time (the time until the apparent expansion of the mixed liquid ends, that is, the time until the urethane foam reaches its maximum amount)
RT). At this time, cell opening (a phenomenon in which the gas pressure generated when the Co foam progresses through a foaming reaction and progresses to a certain level of resin formation destroys the cell membrane of the foam, causing gas to escape from the foam) Observe the presence or absence.

2) Air permeability: An air permeability tester manufactured by Kakushi Seiki Seisakusho in accordance with JIS-L-1004 was used.

3) Compression set, using Combination Tester B type manufactured by Ueshima Seisakusho,
Form size 50m5 x 50+im x 50m
Compress under the test conditions of 70°C x 22hr holding and compression ratio 50χ. The thickness was measured 30 minutes after the load was released.

Table 1 *]: *2: Book 3: Book 4: Book 5: Polyester polyol with a molecular weight of 2000 and a hydroxyl value of 52, manufactured by Kao ■, manufactured from adipic acid, diethylene glycol, and trimethylolpropane.

Polyalkylene oxide methyl siloxane copolymer.

The catalysts used in the evaluation are as follows.

CAT, A, 1-hydroxyethylimidazole CA
T, B, N-ethylmorpholine CAT, C, dimethylaminoethoxyethanol CAT, D, dimethylaminoethoxyethanol CAT, E, 33% dipropylene glycol solution of triethylenediamine The amount of catalyst used is constant in reactivity [cream Time (CT
)=4.5 seconds] was used.

Stannous octoate.

A mixture of 80% 24-tolylene diisocyanate and 20% 2,6-tolylene diisocyanate.

Indicates the molar ratio of polyol and isocyanate functional groups,
INDEX is 100 when OH group/NCO group=1.

Table 2 shows the physical property evaluation results of urethane foam, and Table 3 shows the results of physical property evaluation of urethane foam.
The table shows the odor evaluation results.

Table ◎: No odor Δ: Slight odor ×: Strong odor PPG300
0 (polypropylene glycol, molecular weight 3000)
A 10% solution of.

No metal catalyst used.

From the results in Tables 2 and 3, it can be seen that in the case of the 1-hydroxyimidazole of the present invention, both the odor of the PPG solution and the odor of the foam are odorless, and the physical properties of the foamed urethane foam, especially compression set and aeration. It can be seen that the properties are excellent.

〔Effect of the invention〕

If the catalyst of the present invention is used to foam a soft urethane foam cell, it will not only improve the working environment in the foaming process, but also improve the production of bedding, which is the main application of the soft urethane foam product. The resulting cushioning material and automobile interior seat cushioning material are odorless and have excellent foam properties, making it possible to improve their commercial value.

Claims (1)

[Scope of Claims] 1. A catalyst for producing polyurethane foam, characterized by containing 1-hydroxyethylimidazole. 2. A catalyst for producing polyurethane foam, characterized by containing 1-hydroxyethylimidazole and an organotin compound. 3. A method for producing flexible polyurethane foam, which comprises using 1-hydroxyethylimidazole as a catalyst in producing polyurethane foam by reacting isocyanate and polyol in the presence of a blowing agent and a surfactant. 4. The method for producing a flexible polyurethane foam according to claim 3, characterized in that an organic tin compound is further used as a catalyst.