JP2628099B2 - Manufacturing method of flexible urethane foam - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a flexible urethane foam, and more particularly, to a method using a mixture of a specific polyol and a monool, using water as a blowing agent and polyisocyanate as a polyisocyanate. The present invention relates to a method for producing a flexible urethane foam using tolylene diisocyanate.

2. Description of the Related Art Soft urethane foam is widely used as furniture, furniture, bedding, automobile members, and the like, for example, as a cushion material.

In order to produce flexible urethane foam, polyol,
A one-shot method of forming a foam by mixing and reacting an A component mainly composed of a catalyst, a foam stabilizer and a foaming agent with a B component mainly composed of a polyisocyanate, and performing a foaming process and a curing process in parallel. Is being done.

Conventionally, in the production of a flexible urethane foam, water or a low-boiling compound is used as a foaming agent. Among the flexible urethane foams, low-boiling compounds are used particularly for low-density foams, and a chlorofluorocarbon gas such as trichloromonofluoromethane (hereinafter referred to as chlorofluorocarbon-11) is mainly used. Since this fluorocarbon gas is chemically stable, it diffuses into the stratosphere and destroys the ozone layer present in the stratosphere. As a result, ultraviolet rays radiated from the sun reach the surface of the earth without being absorbed by the ozone layer, and the occurrence of skin cancer has increased. For this reason, from 1989, the use of CFCs will be regulated, and with this, CFC-11 for urethane foam will be used.
Will also be regulated. Therefore, as a foaming agent replacing such chlorofluorocarbon gas, various studies have been made on alternative fluorocarbons, alternative low-boiling compounds, and reduction in density using water, but no suitable foaming agent has yet emerged. As an alternative chlorofluorocarbon, for example, 1,1-dichloro-1 which is referred to as 2,2-dichloro-1,1,1-trifluoroethane (hereinafter chlorofluoro-123) is used.
-Fluoroethane (hereinafter referred to as Freon-141b) and the like have been proposed, but industrial production has not yet been achieved. Alternative low-boiling compounds include, for example, methylene chloride and the like, but their adverse effects on the human body are problematic. On the other hand, in the case of reducing the density using water as a foaming agent, a polyol having a hydroxyl value of 60 mgKOH / g or less has been used as a conventional polyether polyol for flexible urethane foam (Japanese Patent Application Laid-Open No. 64-22915). However, when such a polyol is reacted with a polyisocyanate using only water, the wet heat compression set of the foam becomes extremely large and cannot be put to practical use. There is a problem that it is difficult to apply it to a backrest sheet or the like.

Problems to be Solved by the InventionThe present inventors have conducted intensive research to improve the physical properties of foams and to respond to the social demand for reducing CFCs.By using a mixture of specific polyols and monols, It was also found that a flexible urethane foam exhibiting improved wet heat compression set and having a low hardness can be obtained even if only water is used without using any fluorocarbon gas as a foaming agent. As a result of further studies based on this finding, the present invention has been completed.

Means for Solving the Problems That is, the present invention relates to 1) a polyether polyol 80 having an average number of functional groups of 3 or more and a hydroxyl value of 60 to 100 mgKOH / g.
95% by weight and 2) a monol having a hydroxyl value of 27 to 140 mg KOH / g and an average hydroxyl value of 60 to 90 mg KOH / g
g is reacted with tolylene diisocyanate using 4.5 to 7.0 parts by weight of water per 100 parts by weight of polyol and monol as a foaming agent to produce a flexible urethane foam.

The polyether polyol (1) used in the present invention may be a polyhydric alcohol having a valency of 3 or more such as glycerin, trimethylolpropane, pentaerythritol, methyl glucoside, sorbitol, or sucrose as an initiator. It is produced by addition polymerization with an alkylene oxide using potassium oxide or the like as a catalyst. One or more of the above initiators may be used. Examples of the alkylene oxide include ethylene oxide (hereinafter referred to as EO) and propylene oxide (hereinafter referred to as PO). In the present invention, the thus obtained polyether polyol having a hydroxyl value of 60 to 100 mgKOH / g is used. When the hydroxyl value is lower than 60 mgKOH / g, the wet heat compression set of the foam becomes extremely large, which is not suitable. On the other hand, if it is higher than 100 mgKOH / g, it is difficult to obtain a flexible urethane foam intended in the present invention because a foam cannot be formed or closed cells or foam shrinkage occurs.

This polyether polyol is mixed with the monol of the above item 2). The monol is a monohydric alcohol such as n-butanol, n-propanol, 2-
It is obtained by subjecting an alkylene oxide to addition polymerization in the presence of an alkali metal catalyst in the same manner as in the above polyether polyol 1) using ethylhexyl alcohol and phenols such as phenol and cresol.
As the monol, those having a hydroxyl value of 27 to 140 mgKOH / g are used. The mixing ratio with the polyether polyol of the above 1) is 80 to 95% by weight for 1) and 5 to 20% by weight for 2).
It is.

The average hydroxyl value of the mixture of polyol and monol is 60
9090 mgKOH / g. If it is less than 60 mgKOH / g, the wet heat compression set of the foam becomes large, and if it is more than 90 mgKOH / g, it is difficult to produce the foam. Particularly, by using the monol of 2), one of the urethanization catalysts can be obtained.
Thus, the appropriate usage range of a tin catalyst such as tin octylate is expanded. If the amount of the tin catalyst is less than this range, outgassing, crack collapse, etc. occur,
If the amount of the tin catalyst is larger than this range, a normal foam cannot be formed, for example, the bottom rises, shrinks, and the like tends to be closed cells. In other words, the expansion of the appropriate use amount range is extremely advantageous in producing a normal foam.

Further, when the monol of the above 2) is used, the hardness is significantly reduced as compared with the case where only the polyether polyol of the above 1) is used.

In the present invention, a flexible polyurethane foam is produced by reacting a mixture of the polyol and the monol with a polyisocyanate in the presence of a blowing agent.

The blowing agent used in the present invention is water, and 4.5 to 7.0 parts by weight is used per 100 parts by weight of the total of the polyol and the monol. In addition to water, other known blowing agents can be used in combination.

The polyisocyanate used in the present invention is tolylene diisocyanate (hereinafter referred to as TDI), preferably TDI-80 (a mixture of 2,4-diisocyanate and 2,6-diisocyanate, the ratio of which is 80:20). Is mentioned. Isocyanate index (hereinafter NCO Ind
ex) is 80-120. If it is less than 80, physical properties such as wet heat compression set of the foam may increase, and if it is more than 120, adverse effects such as scorch may be easily generated.

When producing a flexible urethane foam, for example, a foam stabilizer, a catalyst, or the like may be used.

Any foam stabilizer may be used as long as it is called a foam stabilizer for slab foam or a foam stabilizer for hot mold foam. For example, B-8017, B-2370 (manufactured by Goldschmidt), L-582, L-5740M (Nihon Unica Co., Ltd.)
SH-190, SRX-298 (Toray Silicone Co., Ltd.)
Are used. The amount of foam stabilizer used is the total polyol component
0.5 to 2.0 parts by weight per 100 parts by weight.

As the catalyst, for example, a tertiary amine such as triethylenediamine, N-ethylmorpholine, and pentamethyldiethylenetriamine, and a tin catalyst such as stannasoctoate are used in combination.

Other flame retardants (eg, Tris (2,3
-Dichloropropyl) phosphate, a coloring agent, an antioxidant, a viscosity reducing agent (for example, propylene carbonate, etc.) and the like.

The soft urethane foam obtained in this way is of low density, the density of which is
It is a ~25kg / m ³ about.

Effects of the Invention According to the present invention, by using a mixture of a specific polyol and a monol, a low-density flexible urethane foam having improved foam properties can be obtained without using flon gas as a foaming agent and using only water. Can be manufactured.

When a low-density flexible urethane foam is manufactured using a polyol having a hydroxyl value of 60 mgKOH / g or less and water as a foaming agent, the wet heat compression set, which is one of the foam physical properties, becomes extremely large, and is practically used. Although not performed, the flexible urethane foam produced according to the present invention exhibited the same or better wet heat compression set as that using Freon gas, and was additionally produced using Freon gas as a blowing agent. It shows excellent physical properties such as high tensile strength and high elongation as compared with flexible urethane foam of the same density. In particular, by using the monol of 2), 1)
The hardness is greatly reduced as compared with the case where only the polyether polyol is used.

Hereinafter, the present invention will be described specifically with reference to Examples, Comparative Examples, and Reference Examples. In Examples and Comparative Examples, parts and% are by weight.

Example Reference Example 1 3.0 kg of glycerin was placed in a reaction vessel equipped with a heating and stirring device.
And potassium hydroxide in an amount of 0.25% of the end weight at the end of the reaction, and under nitrogen flow, at 110 to 120 ° C., PO 67.3 kg
Was subjected to addition polymerization, and 3.7 kg of EO was further subjected to addition polymerization. After the reaction is complete, add water and synthetic magnesium silicate (Kyoward).
600, manufactured by Kyowa Chemical Industry Co., Ltd.), to which potassium hydroxide was adsorbed, and then removed by filtration. Next, dehydration was performed until the water content became 0.05% or less, and 2,6-di-tert-butyl-4-methylphenol (manufactured by Yoshitomi Pharmaceutical Co., Ltd.)
Was added to a concentration of 1000 ppm.

 This polyol is designated as A, and the analysis values and the like are shown in Table 1.

Reference Examples 2 to 7 Similarly to Reference Example 1, polyols or monols (BG) of Reference Examples 2 to 7 were produced. Table 1 shows the composition and analysis values of the polyol or monol.

Examples 1 and 2, Comparative Examples 1 and 2 A mixture of a polyol and a monol shown in Table 2 was prepared.
A flexible urethane foam was manufactured by the free foaming of the hand mixing method according to the formulation shown in FIG. That is, to 300 g of a mixture of a polyol and a monol, a foam stabilizer, a catalyst, a foaming agent, and other additives are mixed in advance, and stanna octoate is added to the mixture, and after mixing, TDI-8 is immediately mixed.
0 was added and mixed by stirring with a mixer (3000 rpm) for 5 seconds. The mixture was poured into a 27 cm × 27 cm × 25 cm wooden upper open box to produce a urethane foam, and predetermined physical properties were measured.

 The results are also summarized in Table 2.

1) Silicon foaming agent manufactured by Nippon Yunika Co., Ltd. 2) Amine catalyst manufactured by Tosoh Corporation 3) Freon gas manufactured by Showa Denko Corporation 4) Tin catalyst manufactured by Yoshitomi Pharmaceutical Co., Ltd. 5) TDI table manufactured by Takeda Pharmaceutical Co., Ltd. As is clear from -2, when the conventional polyether polyol for slab foam is foamed using only water, the wet heat compression set of the foam becomes extremely large at 23.2% (Comparative Example 1).

In Examples 1 and 2, foaming was performed using only water without using Freon gas, as in Comparative Example 1.
The wet heat compression set of the foam is greatly improved. Furthermore, compared with the case where the chlorofluorocarbon gas of Comparative Example 2 is used together,
Both the tensile strength and the elongation show the same or higher numerical values.
In addition, the hardness is efficiently reduced by using a small amount of monol.

Examples 3 to 5 and Comparative Examples 3 to 6 Soft urethane foams were produced from the mixed polyols shown in Table 3 by the hand mixing method according to the formulations shown in Table 3. That is, for 400 g of the polyol, a foam stabilizer, a catalyst, a foaming agent and other additives are mixed in advance, and stannase octoate is added to the mixture, and after mixing, the mixture is immediately mixed.
TDI-80 was added, and the mixture was stirred and mixed with a mixer (3000 rpm) for 5 seconds. This is 440cm x 440cm x 120c which is adjusted to 37 ± 1 ℃
m, and after foaming was completed, it was cured in a 180 ° C. cure oven for 15 minutes. Liquid temperature is 24 ± 1 ℃
Met. Thereafter, predetermined physical properties were measured. The results are also summarized in Table 3.

As is apparent from Table 3, when foaming was performed using only water without using Freon gas in the conventional polyether for hot mold foam, the wet heat compression set of the foam was reduced.
It increases to 30.2% (Comparative Example 3).

In Examples 3 to 5, foaming was performed using only water without using Freon gas as in Comparative Example 3, but the wet heat compression set of the foam was lower than that in the case where Freon gas was used in combination (Comparative Example 6). , It can be seen that it is equivalent or better. Furthermore, the tensile strength and elongation are
Both show numerical values equal to or higher than Comparative Example 6, and it is clear that the foam produced in the present invention is excellent.

In addition, a relatively small amount of monool efficiently reduces the hardness of the foam.

The physical properties of the foam were determined based on the following test methods.

Hardness JIS-K6401 A 200 mm disc was pressed into a sample by 75% at a speed of 50 mm / min, opened immediately, compressed again by 25% and allowed to stand for 20 seconds, and the load was expressed in kg.

・ Elongation, tensile strength JIS-K6402 Form is punched out with a dumbbell, and this test piece is 300 ~ 5
The film was pulled at a speed of 00 mm / min, and the load at the time of cutting was expressed as tensile strength in kg / cm ² , and the elongation up to that point was expressed as an elongation percentage in%.

-Compression set (Dry Set) JIS-K6401 A 50 mm thick test specimen is compressed to 50% (25 mm) and fixed.
After heating continuously for 22 hours in a constant temperature bath at 70 ± 1 ° C, take out the test piece, remove the test piece from the compression plate, leave it open at normal temperature (23 ° C, 50% RH) for 30 minutes, measure its thickness, and measure the thickness. It is calculated by the formula.

C: Compression set (%) t ₀ : Initial thickness of test piece (mm) t ₁ : Thickness of test piece after test (mm) ・ Heat aging test (wet heat compression set: Wet Set) JASOM− 304 As in the case of compression set, a 50 mm thick test specimen is fixed at 50% (25 mm) and fixed in a thermo-hygrostat at a temperature of 50 ± 2 ° C and a relative temperature of 95% for 22 hours. The test piece is removed from the compression plate, left at room temperature (23 ° C., 50% RH) for 30 minutes, and its thickness is measured and calculated according to the formula (1).

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-109499 (JP, A) JP-A-62-250032 (JP, A) JP-B-44-16914 (JP, B1)

Claims (1)

(57) [Claims] (1) The average number of functional groups is 3 or more, and the hydroxyl value is
60-100mgKOH / g polyether polyol 80-95wt%
And 2) monools having a hydroxyl value of 27 to 140 mg KOH / g,
% By weight of a mixture having an average hydroxyl value of 60 to 90 mgKOH / g as a blowing agent in total of 100
A method for producing a flexible urethane foam, comprising reacting with tolylene diisocyanate using 4.5 to 7.0 parts by weight of water per part by weight.