JP2024038651A - polyurethane foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane foam which has sufficient hardness while securing a high air permeation amount.

SOLUTION: A polyurethane foam is obtained from a composition containing polyol and isocyanate, wherein the polyol contains polymer polyol, polyether polyol (A) having an EO rate of 60 mol% or more, and polyether polyol (B) having an EO rate of less than 60 mol% and a weight average molecular weight of 300 or more and less than 1,500, when the total amount of the polyol is 100 pts.mass, the content of the polymer polyol is more than 10 pts.mass, the content of the polyether polyol (A) is 20 pts.mass or more, and the isocyanate contains a polymeric MDI.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to polyurethane foams.

Patent Document 1 discloses a polyurethane foam using a mixture of a polyether polyol with a low EO rate and a polyether polyol with a high EO rate as a polyol component.
It is disclosed that the urethane foam of Patent Document 1 can ensure the amount of ventilation.
However, the polyurethane foam of Patent Document 1 did not have sufficient hardness.

JP 2020-33553 Publication

The present disclosure has been made in view of the above circumstances, and aims to provide a polyurethane foam that has sufficient hardness while ensuring a high amount of ventilation.

[1] A polyurethane foam obtained from a composition containing a polyol and an isocyanate,
The polyol includes:
polymer polyol;
A polyether polyol (A) having an ethylene oxide unit content of 60 mol% or more when the total amount of alkylene oxide units is 100 mol%;
When the total amount of alkylene oxide units is 100 mol%, the content of ethylene oxide units is less than 60 mol%, and the weight average molecular weight is 300 or more and less than 1500. ,
When the total amount of the polyol is 100 parts by mass,
The content of the polymer polyol is more than 10 parts by mass,
The content of the polyether polyol (A) is 20 parts by mass or more,
A polyurethane foam, wherein the isocyanate includes polymeric MDI.

According to the present disclosure, it is possible to provide a polyurethane foam that has sufficient hardness while ensuring a high amount of ventilation.

[2] The polyurethane foam according to [1], which has a rebound resilience of 25% or less according to JIS K6400-3.

[3] The polyurethane foam of [1] having an air permeability of 50 L/min or more based on JIS K6400-7 A method: 2012.

[4] The polyurethane foam of [1] having a 25% hardness of 20N or more based on JIS K6400-2 D method: 2012.

The present disclosure will be described in detail below. In addition, in this specification, descriptions using "-" for numerical ranges include the lower limit value and the upper limit value, unless otherwise specified. For example, the description "10-20" includes both the lower limit value "10" and the upper limit value "20". That is, "10-20" has the same meaning as "10 or more and 20 or less".

1. Composition The composition includes a polyol and an isocyanate. The composition may contain at least one selected from a blowing agent, a catalyst, a foam stabilizer, and a crosslinking agent as an optional component. Each component of the composition will be explained.

(1) Polyol Polyol is a polymer polyol, a polyether whose content of ethylene oxide units (hereinafter also referred to as "EO units") is 60 mol% or more when the total amount of alkylene oxide units is 100 mol%. When the total amount of polyol (A) and alkylene oxide units is 100 mol%, the content of "EO units" is less than 60 mol% (does not need to contain EO units). (B) is included. The polymer polyol, polyether polyol (A), and polyether polyol (B) may each contain two or more types.

(1.1) Polymer polyol The polymer polyol is not particularly limited. Examples of the polymer polyol include a polymer polyol obtained by polymerizing a vinyl monomer such as styrene and/or acrylonitrile to a polyether polyol (base polyol). The polymer content of the polymer polyol (mass ratio of parts other than the base polyol to the entire polymer polyol) is preferably 10% by mass or more and 55% by mass or less, more preferably 13% by mass or more and 50% by mass or less, and 15% by mass or more. It is more preferable that the amount is 45% by mass or less.

From the viewpoint of ensuring 25% hardness, the content of the polymer polyol is more than 10 parts by mass, preferably 13 parts by mass or more, and more preferably 15 parts by mass or more, when the total amount of polyol is 100 parts by mass. On the other hand, from the viewpoint of compressive residual strain, when the total amount of polyol is 100 parts by mass, it is preferably 55 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 35 parts by mass or less. From these viewpoints, the content of the polymer polyol is preferably more than 10 parts by mass and 55 parts by mass or less, more preferably 13 parts by mass or more and 45 parts by mass or less, and even more preferably 15 parts by mass or more and 45 parts by mass or less. .

The viscosity of the polymer polyol is not particularly limited. The viscosity of the polymer polyol at 25° C. and 60 rpm in a B-type rotational viscometer is preferably 1,500 mPa·s or more and 10,000 mPa·s or less, more preferably 3,000 mPa·s or more and 8,000 mPa·s or less, and even more preferably 4,000 mPa·s. - s or more and 6000 mPa・s or less.

The hydroxyl value of the polymer polyol is not particularly limited. The hydroxyl value of the polyol is preferably 20 mgKOH/g or more and 200 mgKOH/g or less, more preferably 25 mgKOH/g or more and 150 mgKOH/g or less, and still more preferably 30 mgKOH/g or more and 120 mgKOH/g or less.

(1.2) Polyether polyol (A)
The polyether polyol (A) is a polyether polyol having an EO unit content of 60 mol% or more when the total amount of alkylene oxide units is 100 mol%. From the viewpoint of compressive residual strain, the content of EO units is preferably 70 mol% or more, more preferably 75 mol% or more, and even more preferably 80 mol% or more. The upper limit of the content of EO units is not particularly limited, and may be 100 mol%. One type of polyether polyol (A) may be used, or two or more types may be used in combination.
Examples of alkylene oxides other than ethylene oxide used in the production of polyether polyol (A) include propylene oxide, butylene oxide, etc., but propylene oxide is preferably used. As the polyether polyol (A), a polyol whose entire amount is propylene oxide units (hereinafter abbreviated as "PO units") other than EO units can be suitably used.

The content of the polyether polyol (A) is 20 parts by mass or more when the total amount of polyol is 100 parts by mass. The content of the polyether polyol (A) is more preferably 30 parts by mass or more and 40 parts by mass or more from the viewpoint of improving the amount of ventilation. From the viewpoint of moldability and 25% hardness, the upper limit of the content of polyether polyol (A) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. From these viewpoints, the content of the polyether polyol (A) is preferably 20 parts by mass or more and 70 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less, when the total amount of polyol is 100 parts by mass. , more preferably 40 parts by mass or more and 50 parts by mass or less.

The weight average molecular weight of the polyether polyol (A) is not particularly limited. From the viewpoint of achieving low resilience, the weight average molecular weight of the polyether polyol (A) is preferably 20,000 or less, more preferably 10,000 or less, and even more preferably 6,000 or less. The lower limit of the weight average molecular weight of the polyether polyol (A) is preferably 1000 or more, preferably 2500 or more, and even more preferably 4000 or more, from the viewpoint of having a high air permeability. From these viewpoints, the weight average molecular weight of the polyether polyol (A) is preferably 1,000 or more and 20,000 or less, more preferably 2,500 or more and 10,000 or less, and even more preferably 4,000 or more and 6,000 or less.
The weight average molecular weight of the polyether polyol (A) can be measured by gel permeation chromatography (GPC).

The number of functional groups in the polyether polyol (A) is not particularly limited. The number of functional groups in the polyether polyol (A) is preferably 2-5, more preferably 2-4, and still more preferably 2 or 3.

When the number of functional groups of the polyether polyol (A) is within the above range, formation of a network structure can be suppressed when the polyol and isocyanate react. It is presumed that in the polyurethane foam thus formed, entanglement of polyurethane molecules during compression is suppressed, resulting in a polyurethane foam having low compression residual strain.
In addition, in this disclosure, the number of functional groups means the average number of active hydrogen groups that each component contained in the polyol has. When the polyol is a commercially available product, the catalog value may be adopted as the number of functional groups of the polyether polyol (A).

(1.3) Polyether polyol (B)
As the polyether polyol, when the total amount of alkylene oxide units is 100 mol%, the polyether polyol (B) has an EO unit content of less than 60 mol% (does not need to contain EO units). is included. One type of polyether polyol (B) may be used, or two or more types may be used in combination.

Examples of the polyether polyol (B) include polyether polyols containing PO units, butylene oxide units, etc. as alkylene oxide units other than EO units. As the polyether polyol (B), a polyether polyol whose entire amount is PO units other than EO units can be suitably used.

The content of EO units in the polyether polyol (B) is less than 60 mol%. For example, the content of EO units in the polyether polyol (B) is preferably 30 mol% or less, more preferably 15 mol% or less, from the viewpoint of improving the air permeability. The lower limit of the content of EO units in the polyether polyol (B) is not particularly limited, and may be 0 mol%.

The weight average molecular weight of the polyether polyol (B) is 300 or more, preferably 400 or more, and more preferably 500 or more, from the viewpoint of having a low compressive residual strain. On the other hand, the weight average molecular weight of the polyether polyol (B) is less than 1500, preferably less than 1000, and more preferably less than 800, from the viewpoint of having a high 25% hardness. From these viewpoints, the weight average molecular weight of the polyether polyol (B) is 300 or more and less than 1,500, preferably 400 or more and less than 1,000, and more preferably 500 or more and less than 800.
The weight average molecular weight of the polyether polyol (B) can be measured by gel permeation chromatography (GPC).

The number of functional groups in the polyether polyol (B) is not particularly limited. The number of functional groups in the polyether polyol (B) is preferably 2-5, more preferably 2-4, and still more preferably 2 or 3.
When the number of functional groups of the polyether polyol (B) is within the above range, formation of a network structure can be suppressed when the polyol and isocyanate react. It is presumed that the polyurethane foam formed in this manner suppresses the entanglement of polyurethane molecules during compression, resulting in a urethane foam with low compression residual strain.
The polyether polyol (B) is preferably a polyoxyethylene/propylene glycol copolymer or polypropylene glycol with an EO unit content of less than 60 mol%, and a polyoxyethylene/propylene glycol copolymer with an EO unit content of less than 60 mol%. More preferred is a propylene glycol copolymer.

(2) Isocyanate Isocyanate includes polymeric MDI. Polymeric MDI is a mixture of diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate. Diphenylmethane diisocyanate includes 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and 4,4'-diphenylmethane diisocyanate (4,4'-MDI). ).
The polymeric MDI may be untreated crude MDI obtained by an MDI synthesis reaction, or may be one whose composition is adjusted by separating a desired amount of diphenylmethane diisocyanate from the above crude MDI by vacuum distillation. It may be.
The polymeric MDI of the present disclosure preferably contains 4,4'-diphenylmethane diisocyanate (4,4'-MDI).

Polymeric MDI may contain other MDI isocyanates. Other MDI isocyanates include carbodiimide modified products, urethane modified products, urea modified products, allophanate modified products, biuret modified products, isocyanurate modified products of diphenylmethane diisocyanate, and diphenylmethane diisocyanate and these modified products and polyols. Examples include MDI prepolymers obtained by the reaction. Among these, it is preferable that MDI prepolymers are included as other MDI-based isocyanates. Other MDI-based isocyanates may include two types.

The amount of polymeric MDI added is preferably 25 parts by mass or more and 80 parts by mass or less, preferably 30 parts by mass or more and 75 parts by mass or less, and more preferably 35 parts by mass or more and 70 parts by mass or less, based on 100 parts by mass of the polymer polyol.

The content of diphenylmethane diisocyanate in the total amount of polymeric MDI is preferably 35% by mass or more, more preferably 45% by mass or more, and even more preferably 55% by mass or more from the viewpoint of aeration amount. On the other hand, from the viewpoint of 25% hardness, the content is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. From these viewpoints, the content of diphenylmethane diisocyanate in the total amount of polymeric MDI is preferably 35% by mass or more and 90% by mass or less, preferably 45% by mass or more and 85% by mass or less, and more preferably 55% by mass or more and 80% by mass or less.

From the viewpoint of compressive residual strain, the content of polymethylene polyphenyl polyisocyanate in the total amount of polymeric MDI is preferably 10% by mass or more, more preferably 13% by mass or more, and even more preferably 15% by mass or more. On the other hand, from the viewpoint of ventilation amount, the content is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. From these viewpoints, the content is preferably 10% by mass or more and 50% by mass or less, more preferably 13% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less. By adjusting the mass ratio of polymethylene polyphenyl polyisocyanate contained in the polymeric MDI to an appropriate value, a polyurethane foam having a low compressive residual strain and a high air permeability can be obtained.

From the viewpoint of 25% hardness, the isocyanate index (INDEX) is preferably 60 or more, more preferably 70 or more, and even more preferably 75 or more. On the other hand, from the viewpoint of air permeability, it is preferably 120 or less, more preferably 105 or less, and even more preferably 95 or less. From these viewpoints, the isocyanate index (INDEX) is preferably 60 or more and 120 or less, more preferably 70 or more and 105 or less, and even more preferably 75 or more and 95 or less.
The isocyanate index is the value obtained by dividing the number of moles of isocyanate groups in the isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups of polyols and water as a blowing agent, multiplied by 100, and [NCO equivalent of isocyanate/activity] Hydrogen equivalent x 100].

(3) Foaming agent As the foaming agent, water, a fluorocarbon substitute, or a hydrocarbon such as pentane can be used alone or in combination. Water is particularly preferred as the blowing agent. In the case of water, carbon dioxide gas is generated during the reaction between polyol and isocyanate, and the carbon dioxide gas causes foaming. The amount of water as a blowing agent is preferably 0.5 parts by mass or more and 10.0 parts by mass or less, more preferably 1.0 parts by mass or more and 4.0 parts by mass or less, and 2.0 parts by mass or less, more preferably 1.0 parts by mass or more and 4.0 parts by mass or less, based on 100 parts by mass of the polyol. It is more preferably 3.0 parts by mass or more and 3.0 parts by mass or less.

(4) Catalyst A known catalyst for polyurethane foam can be used as the catalyst. As the catalyst, a known urethanization catalyst and/or foaming catalyst can be used. Examples of the catalyst include amine catalysts such as N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, and tetramethylguanidine, and stannous octoate. Examples include tin catalysts such as dibutyltin dilaurate and metal catalysts (also referred to as organometallic catalysts) such as phenylmercury propionate and lead octenoate. The amine catalyst and the metal catalyst may be used together. Two or more types of amine catalysts and metal catalysts may be used. The amount of the catalyst is preferably 0.1 parts by mass or more and 2.0 parts by mass or less, more preferably 0.2 parts by mass or more and 1.0 parts by mass or less, and 0.4 parts by mass, based on 100 parts by mass of the total amount of polyol. The amount is more preferably 0.6 parts by mass or less.

(5) Foam stabilizer The foam stabilizer may be one that is commonly employed as a raw material for urethane foam, and includes, for example, silicone compounds, nonionic surfactants, and the like. The amount of the foam stabilizer is preferably 0.1 parts by mass or more and 4.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3.0 parts by mass or less, and 0.3 parts by mass or less, based on 100 parts by mass of the total amount of polyol. It is more preferably 2.0 parts by mass or more and 2.0 parts by mass or less.

(6) Crosslinking agent A crosslinking agent is blended to improve the hardness and tear strength of the polyurethane foam, and is particularly effective for increasing the hardness. Note that the crosslinking agent is an optional component, and the impact resilience can be reduced even if it is not added.
Examples of the crosslinking agent include polyhydric alcohols such as trimethylolpropane, glycerin, 1,4-butanediol, and diethylene glycol, and amines such as ethanolamines and polyethylene polyamines. Two or more types of crosslinking agents may be used. The total amount of the crosslinking agent is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 0.3 parts by mass or more and 5.0 parts by mass or less, and 0.5 parts by mass, based on 100 parts by mass of the total polyol. Part or more and 3.0 parts by mass or less is more preferable.

(7) Other components Other additives that may be appropriately added include, for example, flame retardants, colorants, and the like.

Flame retardants are added to make polyurethane foam less flammable. Examples of the flame retardant include known liquid flame retardants and solid flame retardants. For example, halogenated polymers such as polyvinyl chloride, chloroprene rubber, and chlorinated polyethylene, phosphoric acid esters and halogenated phosphate ester compounds, organic flame retardants such as melamine resin and urea resin, and antimony oxide and aluminum hydroxide. Examples include inorganic flame retardants. The flame retardant is not limited to one type, and two or more types may be used in combination. The total amount of the flame retardant is preferably 0 parts by mass or more and 10.0 parts by mass or less, more preferably 0.05 parts by mass or more and 8.0 parts by mass or less, and 0.1 parts by mass, based on 100 parts by mass of the total amount of polyol. The amount is more preferably 6.0 parts by mass or less.
The coloring agent is blended to give the polyurethane foam an appropriate color, and the colorant is used depending on the desired color. Examples of the colorant include pigments, graphite, and the like.

2. Physical properties of polyurethane foam The physical properties of polyurethane foam can be set as appropriate depending on the application. Preferably, the polyurethane foam is a flexible polyurethane foam.
The polyurethane foam preferably has the following physical properties.

(1) Apparent core density The apparent core density (JIS K7222) is preferably 10 kg/m ³ or more and 100 kg/m ³ or less, more preferably 20 kg/m ³ or more and 75 kg/m 3 or less, and 30 kg/m ³ or more and 50 kg/m ³ or less. More preferably, it is ³ or less.
(2) 25% hardness The 25% hardness (JIS K6400-2 D method) is preferably 20N or more and 200N or less, more preferably 30N or more and 150N or less, and even more preferably 40N or more and 100N or less.
(3) Repulsion Resilience Repulsion resiliency (JIS K6400-3) is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. Repulsion resilience is usually 0% or more.
(4) Compressive residual strain Compressive residual strain (JIS K6400-4 4.5.2 A method) is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less.
Compressive residual strain was determined by compressing the sample to 50% thickness and leaving it in a drying oven at 70°C for 22 hours, then releasing the compression for 30 minutes, in accordance with JIS K6400-4 4.5.2 A method. The thickness after compression was measured and calculated as the amount of deformation (%) relative to the thickness before compression.
(5) Aeration rate The aeration rate (JIS K6400-7 A method: 2012) is preferably 50 L/min or more, more preferably 100 L/min or more, and even more preferably 150 L/min or more. The ventilation amount is usually 300 L/min or less.

3. Estimated reason for the reduction in compressive residual strain The reason why the compressive residual strain is reduced in the polyurethane foam of the present disclosure is not certain, but it is presumed as follows. However, the present disclosure shall not be construed as limited in any way by this presumed reason.
By using a polyether polyol (A) with an EO unit content of 60 mol% or more, the number of side chains in the polyurethane molecule can be reduced, and entanglement of the polyurethane molecules when the polyurethane foam is compressed can be suppressed. Ru. Then, when the polyurethane foam is compressed, distortion due to the entanglement of polyurethane molecules is less likely to occur, and it is presumed that the foam has a low compressive residual strain.

4. Method for producing polyurethane foam Polyurethane foam can be produced by a known foaming method in which a polyurethane resin composition is stirred and mixed to cause a polyol and an isocyanate to react. Foaming methods include slab foaming, mold foaming, etc., and any molding method may be used.
Slab foaming is a method in which a mixed polyurethane resin composition is discharged onto a belt conveyor and foamed at room temperature under atmospheric pressure.
On the other hand, mold foaming is a method in which a mixed polyurethane resin composition is filled into a mold and foamed within the mold. The mold foaming method is suitable for molded products having complex three-dimensional shapes. For example, it is suitable for molding cushion materials such as seat pads, bedding such as pillows and mattresses, cushions, seat pads, and clothing pads.

5. Applications of Polyurethane Foam The articles in which the polyurethane foam of the present disclosure is used are not limited. Polyurethane foam is suitable for mattresses, and particularly for seat pads for daily necessities.
Body pressure dispersion properties are required as a performance for everyday mattresses. Reducing rebound resilience is effective in improving body pressure dispersion.
Reducing stuffiness is required as a performance feature of mattresses for daily use. Improving ventilation is effective in reducing stuffiness caused by year-round use.
The performance of everyday mattresses is required to be resistant to flattening. High 25% hardness and low compressive residual strain are required for resistance to settling.

Hereinafter, the present disclosure will be specifically explained with reference to Examples.
1. Production of polyurethane foam Compositions blended in the proportions shown in Tables 1 and 2 were prepared, and polyurethane foams of Examples and Comparative Examples were produced by slab foaming.

2. Preparation of polyurethane foam (Example 1-6 and Comparative Example 1-5)
Details of each raw material are as follows. In addition, when the total amount of alkylene oxide units in the polyether polyol is 100 mol%, the content of EO units (mol%) is the "EO rate", and the content of PO units (mol%) is the "PO rate". It is listed in the table.
・Polymer polyol: EXCENOL 941WF manufactured by Asahi Glass Urethane Co., Ltd. (ether-based polymer polyol obtained by graft polymerizing solid contents of acrylonitrile and styrene to polyether polyol, functional group 3, viscosity 5100 mPa・s・25℃, hydroxyl value 32 mgKOH/g)
・Polyether polyol (A): manufactured by Sumika Covestro Urethane Co., Ltd., SBU polyether polyol S240 (number of functional groups 3, weight average molecular weight 5000, EO rate 60 mol% or more, PO rate 40 mol% or less: EO rate and PO rate (The total is 100 mol%.)
・Polyether polyol (B): manufactured by Asahi Denka Kogyo Co., Ltd., G-700 (number of functional groups: 3, weight average molecular weight: 670, hydroxyl value: 250 mgKOH/g, EO rate: 0 mol%, PO rate: 100 mol%)
・Polyether polyol (C): manufactured by Sanyo Chemical Industries, Ltd., GP3050NS (number of functional groups 3, weight average molecular weight 3000, hydroxyl value 56 mgKOH/g, EO rate 10 mol%, PO rate 90 mol%)
・Blowing agent: Water ・Catalyst-1: Amine catalyst 1: DABCO NE300 manufactured by Evonik Japan
・Catalyst-2: Amine catalyst 2 (triethylenediamine 33% by mass): DABCO 33LSI manufactured by Evonik Japan Co., Ltd.
・Foam stabilizer: Silicone foam stabilizer: SZ2904 manufactured by Dow Corning Toray

・MDI-1: Polymeric MDI (mixture of 58% by mass of 4,4'-MDI, 20% by mass of 2,4'-MDI, and 20% by mass of polymethylene polyphenyl polyisocyanate)
・MDI-2: Monomeric MDI (mixture of 4,4'-MDI, 2,4'-MDI), Millionate NM manufactured by Nippon Polyurethane Co., Ltd.
・TDI: Toluene diisocyanate, Coronate T-80 manufactured by Tosoh Corporation

(1) Status of fulfillment of each requirement of Examples 1-6 The composition constituting the polyurethane foam of Examples 1-6 satisfies all of the following requirements (a) to (d).
- Requirement (a): The amount of polymer polyol added is more than 10 parts by mass.
-Requirement (b): The amount of polyether polyol (A) added is 20 parts by mass or more.
- Requirement (c): The weight average molecular weight of the polyether polyol (B) is 300 or more and less than 1,500.
-Requirement (d): Contains polymeric MDI.

(2) Status of satisfaction of each requirement of Comparative Example 1-5 On the other hand, the composition constituting the polyurethane foam of Comparative Example 1-5 does not satisfy the following requirements.
Comparative Example 1 does not meet requirement (c).
Comparative Example 2 does not meet requirement (a).
Comparative Example 3 does not meet requirement (a).
Comparative Example 4 does not meet requirement (d).
Comparative Example 5 does not meet requirement (d).

3. Evaluation method Test pieces were cut out from the polyurethane foam produced using the above raw materials, and the apparent core density, 25% hardness, impact resilience, compressive residual strain, and air permeability were measured by the following methods.
(1) Apparent core density (Kg/m ³ )
The apparent core density (Kg/m ³ ) was measured according to JIS K7222.
The following criteria were used to evaluate the apparent core density.
"A": 25 (Kg/m ³ ) or more and 45 (Kg/m ³ ) or less.
"C": less than 25 (Kg/m ³ ) or greater than 45 (Kg/m ³ ).
(2) 25% hardness (N)
25% hardness (N) was measured according to JIS K6400-2 D method.
The evaluation of 25% hardness (N) was based on the following criteria.
"A": 40 (N) or more.
"B": 20 (N) or more and 40 (N) or less.
"C": Less than 20 (N).
(3) Resilience Resilience (%) was measured according to JIS K6400-3.
The evaluation of impact resilience (%) was based on the following criteria.
"A": 15 (%) or less.
"B": Greater than 15 (%) and equal to or less than 25 (%).
"C": Greater than 25 (%).
(4) Compressive residual strain Compressive residual strain (%) was measured according to JIS K6400-4 4.5.2 A method.
The evaluation of compressive residual strain (%) was based on the following criteria.
"A": 5 (%) or less.
"B": greater than 5 (%) and less than or equal to 10 (%).
"C": Greater than 10 (%).
(5) Aeration rate The aeration rate (L/min) was measured according to JIS K6400-7 A method: 2012.
The evaluation of ventilation amount (L/min) was based on the following criteria.
"A": 150 (L/min) or more.
"B": 50 (L/min) or more.
"C": Less than 50 (L/min).
(6) Overall rating "A": All evaluation items (1) to (5) are A.
"B": Rated "A" or "B" in evaluation items (1) to (5).
“C”: Any of the evaluation items (1) to (5) is rated “C”.

4. Results The results are also listed in Tables 1 and 2.

The overall evaluation result for the polyurethane foam of Examples 1-6 that satisfied all requirements (a) to (d) was A or B.
The impact resilience of the polyurethane foams of Examples 1-6, which satisfied all requirements (a) to (d), was 25% or less.
The air permeability of the polyurethane foams of Examples 1-6 that satisfied all requirements (a) to (d) was 50 L/min or more.
The 25% hardness of the polyurethane foams of Examples 1-6 that satisfied all requirements (a) to (d) were all 20N or more.

5. Discussion In Example 1, hardness, impact resilience, and compressive residual strain were improved by 25% compared to Comparative Example 5. The urethane foam of the present disclosure significantly improves each characteristic value by containing polymethylene polyphenyl polyisocyanate. In particular, in the urethane foam of the present disclosure, it is more preferable that the polymeric MDI contains polymethylene polyphenyl polyisocyanate in a proportion of 15% to 30% by mass based on the total amount of the polymeric MDI.
Examples 1, 2, and 3 had better ventilation than Examples 4, 5, and 6. The isocyanate INDEX of the urethane foam of the present disclosure is more preferably 75 or more and 95 or less.

6. Effects of Examples According to the above examples, it is possible to provide a polyurethane foam that has sufficient hardness while ensuring a high amount of ventilation.

The present disclosure is not limited to the embodiments detailed above, and various modifications or changes can be made within the scope of the present disclosure.

Claims (4)

A polyurethane foam obtained from a composition comprising a polyol and an isocyanate,
The polyol includes:
polymer polyol;
A polyether polyol (A) having an ethylene oxide unit content of 60 mol% or more when the total amount of alkylene oxide units is 100 mol%;
When the total amount of alkylene oxide units is 100 mol%, the content of ethylene oxide units is less than 60 mol%, and the weight average molecular weight is 300 or more and less than 1500. ,
When the total amount of the polyol is 100 parts by mass,
The content of the polymer polyol is more than 10 parts by mass,
The content of the polyether polyol (A) is 20 parts by mass or more,
A polyurethane foam, wherein the isocyanate includes polymeric MDI. The polyurethane foam according to claim 1, having a rebound resilience according to JIS K6400-3 of 25% or less. The polyurethane foam according to claim 1, having an air permeability of 50 L/min or more based on JIS K6400-7 A method: 2012. The polyurethane foam according to claim 1, having a 25% hardness of 20N or more based on JIS K6400-2 D method: 2012.