JPH1160676A - Method for producing flexible polyurethane foam - Google Patents

Abstract

(57) [Problem] To provide a flexible polyurethane foam used for automobile seats with a low density, a high durability, and an appropriate rebound resilience and hysteresis loss in order to give a moist luxury feeling. Is done. However, it has been difficult to suppress the rebound resilience moderately low without sacrificing the density and durability and to moderately increase the hysteresis loss. In the present invention, a polyol component as a raw material of urethane foam has an average number of functional groups of 2.5 to 2.5.
8. An average number of functional groups containing not less than 45% by weight of a polyoxyalkylene polyol having a hydroxyl value of 10 to 35 mgKOH / g is 2.5.
Polyol having a hydroxyl value of 10 to 40 mgKOH / g (A
1) was added to 70 to 95 parts by weight of a polyol (A2) having an average functional group number of 2 to 5 and a hydroxyl value of 90 to 300 mgKOH / g.
The problem has been solved by using 30 parts by weight.

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 highly elastic and highly durable polyurethane foam in which the rebound resilience and the hysteresis loss are controlled in appropriate ranges.

[0002]

2. Description of the Related Art Soft urethane foams are widely used as cushioning materials for automobile seats, bedding, sofas and other furniture. 2. Description of the Related Art In recent years, due to the high-grade orientation of automobiles, high running stability including ride comfort characteristics and safety aspects of automobile seats has been required. Automobile seats are basically composed of urethane foam pads, springs, frames, etc. Among them, the urethane mold foam used as pad material is used as a cushioning material that directly supports the occupant, providing ride comfort and running stability. Plays a big role in gender. Recently, in order to produce a urethane molded foam having improved rebound resilience, durability and vibration characteristics, particularly for the purpose of improving ride comfort characteristics, a high molecular weight polyoxyalkylene polyol having an extremely small content of impurities such as monools has been developed. U.S. Pat. The urethane mold foam using a high molecular weight polyoxyalkylene polyol having an extremely low impurity content such as a monool has a vibration frequency range (4-8 Hz, Or 6-20Hz
Is said to be high, and the ride quality is considerably improved.

[0003]

However, a urethane molded foam using such a high-molecular-weight polyoxyalkylene polyol having a small amount of impurities has an extremely high rebound resilience and an extremely low hysteresis loss rate of the foam. The vibration transmissibility near the resonance point is extremely high, so the rider feels a large amount of push-up and instability from the seat when traveling, and also has a large push-up feeling when stopping, which is still insufficient in terms of ride comfort. It is supposed to be. In order to reduce these feelings of thrust and instability, the rebound resilience of the foam is moderately low,
Foams whose physical properties are controlled so that the hysteresis loss is moderately large are considered more suitable, but it has been difficult to produce a foam having these characteristics without sacrificing durability.

[0004]

Means for Solving the Problems The present inventors have found that the overall density is 35 kg / m ³ or more and the rebound resilience of the core portion is 50 to 68.
%, The hysteresis loss ratio is 25 to 35%, and the dry heat compression set is 10% or less, preferably 7% or less.
As a result of intensive studies aimed at producing urethane foams having physical properties of a wet heat compression set of 15% or less, preferably 13% or less, the use of a specific polyol component achieves the purpose. Having found that, the present inventors completed further research and completed the present invention. That is,
The present invention provides (1) a method for producing a flexible polyurethane foam in which a mixture comprising a polyol component, a crosslinking agent, a catalyst, a foaming agent, a foam stabilizer, and other auxiliaries is reacted with a polyisocyanate; In the presence, an average functionality of 2.5 to 8 obtained by addition polymerization of an alkylene oxide to an active hydrogen compound and an average functionality of at least 45 wt% of a polyoxyalkylene polyol having a hydroxyl value of 10 to 35 mgKOH / g.
5 to 8, 70 to 95 parts by weight of a polyol (A1) having a hydroxyl value of 10 to 40 mgKOH / g, and a polyol (A2) of 5 to 5 having an average functional group number of 2 to 5 and a hydroxyl value of 90 to 300 mgKOH / g.
(2) a polyol (A1) having an average functional group number of 2.8 to 5 and a hydroxyl value of 15;
-35 mgKOH / g, the content of ethylene oxide in the polyoxyalkylene polyol is 10 to 20% by weight,
(1) The production method according to the above (1), wherein the terminal primary OH is 40 to 90 mol%, (3) the polyol (A2) has an average number of functional groups of 2 to 4 and a hydroxyl value of 110 to 280 mgKOH / g. (1) The production method described in (1), (4) Polyol (A
In 1), the production method according to the above (1), wherein the total amount of the trifunctional or higher functional polyol is 75 mol% or more; The above (1) using 0 to 15 parts by weight of carbon dioxide gas
And (6) the production method according to (1), wherein the polyisocyanate is tolylene diisocyanate which may contain 30% by weight or less of polymethylene polyphenyl polyisocyanate.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyol (A1) used in the method of the present invention has an average number of functional groups of 2.5 to 8 which is produced by addition polymerization of an alkylene oxide to an active hydrogen compound using a cesium hydroxide catalyst. Preferably 2.8 to 5
With a hydroxyl value of 10 to 35 mg KOH / g, preferably 15
The average number of functional groups containing at least 45% by weight, preferably at least 50% by weight of a polyoxyalkylene polyol of from 30 to 30 mg KOH / g is from 2.5 to 8, preferably from 2.8 to 5, more preferably from 3 to 4, and a hydroxyl value of from 10 to 10 40 mg KOH / g,
It is preferably 15 to 35 mgKOH / g, more preferably 20 to 28 mgKOH / g. Examples of the polyol (A1) include a polyoxyalkylene polyol obtained by using the cesium hydroxide catalyst, a so-called polymer polyol obtained by polymerizing a vinyl monomer in the polyol, and the above-mentioned polyol due to the need for hardness. Examples thereof include ordinary polyoxyalkylene polyols obtained using a potassium hydroxide catalyst or the like, and a mixture with a polymer polyol obtained by polymerizing a vinyl monomer in the polyol. Examples of the polyoxyalkylene polyol include those obtained by adding an alkylene oxide to an active hydrogen compound such as alcohols, amines, and ammonia. Examples of alcohols include monohydric alcohols (eg, methanol and ethanol), dihydric alcohols (eg, ethylene glycol and propylene glycol), and trihydric alcohols (eg, glycerin,
And polyhydric alcohols such as tetrahydric alcohols and octahydric alcohols. Examples of the amines include monovalent amines (dimethylamine,
Diethylamine, etc.) divalent amines (methylamine, ethylamine, etc.) trivalent amines (monoethanolamine, diethanolamine, triethanolamine, etc.),
And polyvalent amines such as tetravalent amines.

As the alkylene oxide, ethylene oxide, propylene oxide, 1,2-, 1,4
-And 2,3-butylene oxide and their 2
Combinations of more than one species may be mentioned. Among these, preferred are ethylene oxide and / or propylene oxide, and when used in combination, the addition form may be either block or random. The polymer polyol is obtained by polymerizing a vinyl monomer such as acrylonitrile and styrene in the presence of a radical in a polyoxyalkylene polyol or a normal polyoxyalkylene polyol obtained using the cesium hydroxide catalyst exemplified above, and stably dispersing the polymer. To be obtained. The content of the vinyl polymer in each polymer polyol is usually 5 to 45% by weight, preferably 10 to 35% by weight. The hydroxyl value of the polyol (A1) is usually 10 to 40 mgKOH / g.
It is. Polyol (A1) has a hydroxyl value of 10 mg KO
If it is less than H / g, even if a polyoxyalkylene polyol produced using a cesium hydroxide catalyst is used as (A1), the content of the diol, monool, etc. in the polyol will be large, and the durability of the produced urethane foam will be high. Is reduced. Also, when the hydroxyl value in the polyol (A1) exceeds 40 mgKOH / g, the durability of the produced urethane foam also decreases. Polyol (A
The polyoxyalkylene polyol contained in 1) preferably has an ethylene oxide structure content of 10 to 20% by weight in the alkylene oxide structure.
Those having a grade OH of 40 to 90 mol% are preferred. From the viewpoint of the durability of the obtained foam, the polyol (A
The total of the trifunctional or higher polyols in 1) is preferably at least 75 mol%, more preferably at least 80 mol%. Cesium hydroxide, which is a catalyst used for producing the polyoxyalkylene polyol of the polyol (A1), usually has a purity of 90% by weight or more, preferably 95% by weight or more. In general, when propylene oxide is addition-polymerized to an active hydrogen compound in the presence of an alkali metal hydroxide catalyst, a considerable amount of monol is by-produced. Parts, usually 95-11
5 ° C, preferably 99-105 ° C, maximum pressure 3.5Kg
When propylene oxide is subjected to addition polymerization at / cm ² , a polyoxyalkylene polyol having a low content of monool and diol can be produced. After completion of the reaction of the alkylene oxide, the catalyst is removed by a neutralization method, an adsorption method, a water washing method, an ion exchange method or the like in the same manner as in a usual method for producing a polyoxyalkylene polyol.

As the polyol (A2) used in the method of the present invention, a polyether polyol usually used for polyurethane is used. Examples of the polyether polyol include those obtained by adding an alkylene oxide to an initiator such as water, alcohols, amines, and ammonia. Examples of the alcohols include monohydric alcohols (methanol, ethanol, etc.), dihydric alcohols (ethylene glycol, propylene glycol, etc.), 3
And polyhydric alcohols such as hydric alcohols (such as glycerin and trimethylolpropane), tetrahydric alcohols (such as D-sorbitol), hexahydric alcohols, and octahydric alcohols. As amines, monovalent amines (dimethylamine, diethylamine, etc.), divalent amines (methylamine, ethylamine, etc.), trivalent amines (monoethanolamine, diethanolamine, triethanolamine, etc.), tetravalent amines, etc. Of polyvalent amines.
Examples of the alkylene oxide include ethylene oxide (EO), propylene oxide (PO), 1,2-,
1,4- and 2,3-butylene oxide and a combination of two or more of these. Of these, preferred are propylene oxide and / or ethylene oxide, and when used in combination, the addition form may be either block or random.

Each of the polyols (A1) and (A2) may be a single compound or a mixture of two or more compounds. When they are a mixture of two or more compounds, the number of functional groups and the hydroxyl value of each of the constituent compounds may include those which are out of the ranges of the average number of functional groups and the hydroxyl value described above, and the polyol (A1) or What is necessary is just to satisfy | fill the said average functional group and the average hydroxyl value range of the whole composition of a polyol (A2). The hydroxyl value of the polyol (A2) is usually from 90 to 300.
mgKOH / g, preferably 110-280 mgKOH / g, 9
If it is less than 0, no remarkable decrease in rebound resilience and increase in hysteresis loss rate are observed as compared with a foam using only polyol (A1) as a polyol. Inferior foam and reduced heat resistance. The average number of functional groups of the polyol (A2) is usually 2 to 5, preferably 2 to 4. (A
Assuming that the total of 1) and (A2) is 100 parts by weight, the usage ratio of the polyols (A1) and (A2) is usually (A1) 70
To 95 parts by weight, (A2) 30 to 5 parts by weight, preferably
(A1) 75 to 90 parts by weight, (A2) 25 to 10 parts by weight, more preferably (A1) 80 to 87 parts by weight, (A1)
2) 20 to 13 parts by weight. If the amount of (A2) is less than 5 parts by weight, the desired reduction in rebound resilience and the increase in the hysteresis loss rate are not observed, and if the amount of (A2) exceeds 30 parts by weight, rebound is obtained. In a relatively low density region where the elastic modulus is less than 50% and the density is 35 to 40 kg / m ² ,
Dry heat compression set and wet heat compression set are deteriorated and durability is reduced.

As the catalyst (B), known catalysts usually used for the production of polyurethane, for example, tertiary amines (triethylamine, trimethylenediamine, N-methylmorpholine, etc.), and quaternary ammonium salts (tetraethylhydroxylammonium) Etc.), imidazoles (imidazole, 2-ethyl-4-methylimidazole, etc.) and the like. Of these, preferred are tertiary amines and imidazoles. As the organic polyisocyanate (C), known ones usually used for the production of polyurethane, for example, tolylene diisocyanate (TDI), modified TDI, diphenylmethane diisocyanate (MDI), crude MDI (c-MDI), that is, polymethylene polyisocyanate Carbon number of phenyl polyisocyanate and modified MDI, etc. (excluding carbon number in NCO group) 6 to
20 aromatic polyisocyanates, and combinations of two or more thereof. Of those exemplified as (C), preferred are TDI and c-MDI in a weight ratio of 100/0 to 70/30, preferably 95/5 to 5/30.
75/25. In the method of the present invention, a crosslinking agent (D) can be used if necessary. As (D), those which can be usually used for producing a polyurethane foam are used, and examples thereof include monoethanolamine, diethanolamine, and triethanolamine.

In the method of the present invention, a foam stabilizer (E) can be used if necessary. As (E), a silicone-based foam stabilizer (polyoxyalkylene-dimethylpolysiloxane-based copolymer) which can be usually used for the production of a flexible polyurethane foam is used, for example, SZ-1311, SZ manufactured by Nippon Unicar Co., Ltd. -1313, Toray
SRX-274 manufactured by Dow Corning Silicon Co., Ltd.
C, a foam stabilizer such as B-4113 manufactured by Goldschmidt Co., Ltd., and the like. As the foaming agent (F), water, liquefied carbon dioxide, and halogenated hydrocarbons such as trichloromonofluoromethane, dichlorodifluoromethane, methylene chloride, and trichlorofluoromethane can be used alone or in combination. From the viewpoint of environmental protection, water alone or a combination of water and liquefied carbon dioxide is preferable. The amounts of the components (B) to (F) used in the production method of the present invention are as follows. (B) is usually 0.01 to 5 parts by weight, preferably 0.5 to 3 parts by weight, per 100 parts by weight of (A1). (C) is an amount that gives an NCO index of 75 to 125, preferably 85 to 115. (D) is (A
1) Usually 0 to 5 parts by weight based on 100 parts by weight.
(E) is usually 0 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of (Al).

Water as the blowing agent (F) is (A1) 100
Usually 1 to 6 parts by weight, preferably 1.5 to 5 parts by weight
It is 5.0 parts by weight, more preferably 2.0 to 4.0 parts by weight. If the amount of water exceeds 6 parts by weight, the moldability of the foam deteriorates and the durability also deteriorates. As the foaming agent, liquefied carbon dioxide gas together with water may be used in an amount of usually 15 parts by weight or less, preferably 10 parts by weight or less based on 100 parts by weight of (A1). As other additives, additives, antioxidants, anti-deterioration agents, flame retardants, coloring agents and the like which are usually used for urethane foam raw materials can be used as required.
(A), (B), (F) and if necessary (D),
A mixture of the components (E) and (C) is stirred and mixed by a usual method for producing a flexible urethane foam, and the mixture is foamed in a fixed mold to obtain a highly elastic flexible polyurethane mold foam.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition, the numerical value of the foaming prescription column in Examples and Comparative Examples indicates parts by weight. Examples 1 to 6 and Comparative Examples 1 to 5 Foaming in the present invention was evaluated using polyols and polyisocyanates obtained by the following methods. Polyol A1-1: 0.2 mol of a cesium hydroxide catalyst was added to 1 mol of glycerin, and dehydration under reduced pressure was performed at 120 ° C. for 4 hours, and then propylene oxide was added at a temperature of 100 ° C. and a pressure of 3.0 kg / cm ^2. After polymerization, ethylene oxide was reacted at a temperature of 100 ° C. under a pressure of 2.5 kg / cm ² to obtain an ethylene oxide content (EO%) of 15% by weight and a hydroxyl value of 24 mg KO.
H / g polyoxyalkylene polyol. Polyol A1-2: Addition of 0.32 mol of potassium hydroxide catalyst to 1 mol of glycerin, dehydration under reduced pressure at 120 ° C. for 4 hours, and then addition polymerization of propylene oxide at 105 ° C. and 3.0 kg / cm ^2. Then, a polyoxyalkylene polyol having a hydroxyl value of 24 mgKOH / g and having an EO% of 15% by weight obtained by reacting ethylene oxide at a temperature of 115 ° C. and a pressure of 2.5 kg / cm ² .

Polyol A1-3: 0.2 mol of a cesium hydroxide catalyst was added to 1 mol of glycerin, and
After dehydration under reduced pressure for a period of time, propylene oxide is reacted, followed by ethylene oxide.
A heavy polyol having a polymer content of 20% by weight in which an acrylonitrile monomer is addition-polymerized and stably dispersed in a polyoxyalkylene polyol having an O% of 12% by weight and a hydroxyl value of 34 mgKOH / g in the presence of a radical. Polyol A1-4: A polymer polyol having a polymer content of 20% by weight in which an acrylonitrile monomer is addition-polymerized and stably dispersed in the presence of a radical in the polyol A1-1. Polyol A2-1: A potassium hydroxide catalyst (0.030 mol) was added to 1 mol of glycerin, dehydration was performed under reduced pressure at 120 ° C. for 4 hours, and propylene oxide was reacted to obtain a polyhydric polymer having a hydroxyl value of 250 mgKOH / g. Oxyalkylene polyol. Polyol A2-2: 0.047 mol of a potassium hydroxide catalyst was added to 1 mol of glycerin, dehydration was performed at 120 ° C. under reduced pressure for 4 hours, and propylene oxide was reacted to obtain a polyhydric polymer having a hydroxyl value of 160 mg KOH / g. Oxyalkylene polyol.

Polyol A3-1: 0.14 mol of potassium hydroxide catalyst was added to 1 mol of glycerin,
After dehydration under reduced pressure for 4 hours, a polyoxyalkylene polyol having EO% of 12% by weight and a hydroxyl value of 56 mgKOH / g obtained by reacting propylene oxide and subsequently reacting with ethylene oxide was obtained. Catalyst B-1: 70% of bis- (2-dimethylaminoethyl) ether
DPG solution Trade name; TOYOCAT ET (Tosoh Corp., amine catalyst) Catalyst B-2: 33% DPG solution of triethylenediamine Trade name; TEDA (Tosoh Corp., amine catalyst) Crosslinking agent D-1: Diethanolamine (Nippon Shokubai Kagaku) Industrial Co., Ltd.), hydroxyl value 1603 mgKOH / g, average number of functional groups 3.0. Crosslinking agent D-2 0.02 mol of potassium hydroxide catalyst was added to 1 mol of trimethylolpropane, and after dehydration under reduced pressure at 120 ° C. for 4 hours, a hydroxyl value of 920 mgKOH / g obtained by reacting ethylene oxide was obtained. Polyoxyalkylene polyol having an average number of functional groups of 3.0.

Silicon foam stabilizer E-1 SZ-1313 (manufactured by Nippon Unicar, foam stabilizer) Silicon foam stabilizer E-2 SF-2969 (manufactured by Dow Corning Toray Silicone Co., Ltd.) Isocyanate C TDI -80 / c-MDI mixed at 80/20 weight ratio. Trade name: Takenate TM-20 (Isocyanate manufactured by Takeda Pharmaceutical Co., Ltd.) A polyol, pure water, a foam stabilizer, and a catalyst are mixed in advance in the mixing ratio shown in [Table 1], and the liquid temperature is adjusted to 25 ±. Adjusted at 2 ° C. A predetermined amount of the isocyanate whose solution temperature was adjusted to 25 ± 2 ° C. was added thereto, and the mixture was stirred and mixed with a high-speed mixer for 5 seconds.
400mm × 400mm × 100mm temperature adjusted to about 62 ℃
Was injected into an aluminum mold. After curing for 5 minutes, the sample was taken out and allowed to stand for 24 hours or more, and then various foam properties shown in Table 2 were measured. The foam properties were in accordance with JIS K6301 and JIS K6401.

[0016]

[Table 1]

[0017]

[Table 2]

In Examples 1 to 6, as shown in Table 2, the hysteresis loss was large and the rebound resilience was 5
Mold foams having good physical properties of 7 to 66%, a hysteresis loss rate of 25 to 33%, a dry heat compression set of 5% or less, and a wet heat permanent set of 13% or less were produced. In Comparative Examples 1, 2, and 2, the polyol A2 was not contained at all, but a highly durable foam having an extremely high rebound resilience and an extremely small hysteresis loss rate was obtained. Comparative Example 3 uses a polyoxyalkylene polyol produced using a potassium hydroxide catalyst as the polyol A1, and the obtained foam has a slightly increased hysteresis loss rate and a reduced rebound resilience rate. , Dry heat and wet heat compression set increased, and durability decreased.
In Comparative Example 4, the addition amount of the polyol A2 was 3 parts by weight with respect to 97 parts by weight of A1. In this case, the rebound resilience and hysteresis loss could not be controlled within the desired ranges. In Comparative Example 5, polyol A3-1 having a hydroxyl value of 56 mgKOH / g was used in place of polyol A2. In this case, too, the rebound resilience and hysteresis loss could not be controlled within the desired ranges. Was.

[0019]

The soft and highly elastic molded foam obtained by the method of the present invention has a core density of 35 kg / m ³ or more, a rebound resilience of 50 to 68%, and a hysteresis loss of 25 to 50%.
It has physical properties of 35%, dry heat compression set of 7% or less, and wet heat compression set of 13% or less, and is useful as a highly durable automobile seat cushion material with little feeling of pushing up and instability during running of a car. It is.

Continuing on the front page (72) Inventor Hiroyuki Aratani 2-17-85, Jusanhoncho, Yodogawa-ku, Osaka-shi, Osaka Takeda Pharmaceutical Company Limited Chemical Company

Claims (6)

[Claims] 1. A polyol component, a crosslinking agent, a catalyst, a foaming agent,
In a process for producing a flexible polyurethane foam in which a mixture comprising a foam stabilizer and other auxiliaries is reacted with a polyisocyanate, an average functionality obtained by addition-polymerizing an alkylene oxide to an active hydrogen compound in the presence of a cesium hydroxide catalyst as a polyol component. Number of groups 2.5 to 8, hydroxyl value 1
The average number of functional groups comprising at least 45% by weight of a polyoxyalkylene polyol of 0 to 35 mgKOH / g is 2.5 to 2.5.
8. Polyol having a hydroxyl value of 10 to 40 mgKOH / g (A
1) 70 to 95 parts by weight of a polyol (A2) having an average number of functional groups of 2 to 5 and a hydroxyl value of 90 to 300 mgKOH / g (A2)
A method for producing a flexible polyurethane foam, characterized by using a composition consisting of parts by weight. 2. The polyol (A1) has an average number of functional groups of 2.
8 to 5, hydroxyl value is 15 to 35 mgKOH / g, ethylene oxide content in polyoxyalkylene polyol is 1
The method according to claim 1, wherein the amount is 0 to 20% by weight and the terminal primary OH is 40 to 90% by mole. 3. The polyol (A2) has an average number of functional groups of 2 to 2.
4. The method according to claim 1, wherein the hydroxyl value is 110 to 280 mgKOH / g. 4. The method according to claim 1, wherein the total amount of the polyol having three or more functional groups in the polyol (A1) is 75 mol% or more. 5. The method according to claim 1, wherein 1 to 6 parts by weight of water and 0 to 15 parts by weight of liquefied carbon dioxide are used as a foaming agent with respect to 100 parts by weight of the polyol (A1). 6. The method according to claim 1, wherein the polyisocyanate is tolylene diisocyanate which may contain 30% by weight or less of polymethylene polyphenyl polyisocyanate.