Patent Application
20250214494
The present invention relates to a seat pad, and more particularly to a seat pad composed of a polyurethane foam small in both compressive residual strain and wet heat compressive residual strain.
Seats for an automobile are classified into a type in which a seat cushion (seat surface portion) and a seat back (back surface portion) are separated from each other and a type in which they are integrated with each other.
Further, the seat for an automobile generally includes:
A polyurethane foam is generally used in the seat pad.
When an occupant sits on a seat for an automobile including a seat pad, the seat pad is compressed in a load direction in proportion to a magnitude of a load applied to the seat pad. The magnitude of the load applied to the seat pad varies depending on the shape of the seat for an automobile, the inclination of the seat back, the part of the human body in contact with the seat for an automobile, the posture of the occupant, the uneven state of the road surface on which the automobile travels, and the like. Therefore, even when the shape of the seat pad is optimized while it is not in use, residual strain (compressive residual strain, wet heat compressive residual strain) may occur in the seat pad due to stuffiness, temperature, compressive stress, and the like during use, resulting in a seat having poor seating comfort.
In order to solve this problem, various proposals have conventionally been made.
For example, Patent Literature 1 discloses a seat pad that is not intended to reduce compressive residual strain and/or wet heat compressive residual strain, but has different hardnesses along a thickness direction.
Patent Literature 1 describes that varying the hardness of the seat pad along the thickness direction makes it possible to reduce the weight of the seat pad while suppressing a feeling of wobbling.
Patent Literature 2 discloses a soft polyurethane foam obtained by reacting raw materials containing a polymer polyol (N), a polyether polyol (A1), and a polyisocyanate component (B), which satisfy predetermined conditions.
Patent Literature 2 describes that such a method provides a soft polyurethane foam having a 25% compressive hardness of 250 to 280 (N/314 cm2), a moderate hysteresis loss rate, and reduced stress relaxation.
Patent Literature 3 discloses a polyol composition containing a polyether polyol (a1), a vinyl polymer (p), and a foam stabilizer composed of a low molecular weight siloxane (c1), which satisfy predetermined conditions.
Patent Literature 3 describes that the use of such a polyol composition provides an elastic polyurethane foam having a low wet heat residual strain rate.
Patent Literature 4 discloses a polyol component (a) containing a polyether polyol (a1) and a vinyl polymer (p), which satisfy predetermined conditions.
Patent Literature 4 describes that when such a polyol component (a), an organic polyisocyanate component (b), and water are subjected to a foaming reaction in the presence of a catalyst (c), an elastic polyurethane foam having a low wet heat residual strain rate is obtained.
Patent Literatures 3 and 4 describe that, in the case of manufacturing a polyurethane foam, the use of a polyol satisfying specific conditions reduces wet heat residual compressive strain. However, in general, when either the wet heat compressive residual strain or the compressive residual strain is reduced, the other tends to be increased.
An object of the present invention is to provide a seat pad composed of a polyurethane foam and small in both compressive residual strain and wet heat compressive residual strain.
Another object of the present invention is to provide a seat pad composed of a polyurethane foam, small in both compressive residual strain and wet heat compressive residual strain, and having a moderate hardness.
In order to achieve the objects, a seat pad according to the present invention includes
The “compressive residual strain ε1” refers to a value (temperature: 70° C., compression rate: 50%) as measured in accordance with JIS K 6400-4, and
The polyurethane foam preferably has a 25% hardness of 150 N or more.
Preferably, the polyurethane foam is obtained by reacting a raw material mixture containing a polyol component and a polyisocyanate component,
In the case of manufacturing a polyurethane foam, the use of a raw material mixture containing a polyether polyol A and carbodiimide-modified MDI which satisfy predetermined conditions provides a polyurethane foam small in both compressive residual strain ε1 and wet heat compressive residual strain ε2. Further, optimization of manufacturing conditions provides a polyurethane foam having a 25% hardness of 150 N or more.
It is considered that the compressive residual strain ε1 is decreased because the rigidity of the polyurethane foam is increased due to the use of a polyether polyol A having a large number of functional groups and a large weight average molecular weight.
It is considered that the wet heat compressive residual strain ε2 is decreased because the use of a polyether polyol A having a high EO content rate increases water absorbability so that the restoring force by the absorbed water is increased.
Furthermore, it is considered that the hardness is moderately increased because the number of crosslinking points is increased due to the use of a polyether polyol A having a large number of functional groups.
Hereinafter, embodiments of the present invention will be described in detail.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture containing a polyol component and a polyisocyanate component. The raw material mixture usually further contains a crosslinking agent, a foaming agent, and a catalyst.
The polyurethane foam constituting the seat pad is obtained by foaming and reacting a raw material mixture satisfying predetermined conditions. Details of a method for manufacturing the polyurethane foam will be described later.
The “compressive residual strain ε1” refers to a value (temperature: 70° C., time: 22 hours, compression rate: 50%) as measured in accordance with JIS K 6400-4.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention has a small compressive residual strain ε1. When the manufacturing conditions are optimized, the ε1 of the polyurethane foam is 5.0% or less. When the manufacturing conditions are further optimized, the ε1 is 4.0% or less, or 3.5% or less.
The “wet heat compressive residual strain ε2” refers to a value (temperature: 50° C., humidity: 95% RH, time: 22 hours, compression rate: 50%) as measured in accordance with JIS K 6400-4.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention has a small wet heat compressive residual strain ε2. When the manufacturing conditions are optimized, the ε2 of the polyurethane foam is 5.0% or less. When the manufacturing conditions are further optimized, the ε2 is 4.0% or less, 3.5% or less, 3.0% or less, or 2.0% or less.
The “strain ratio ε2/ε1” refers to a ratio of the wet heat compressive residual strain ε2 to the compressive residual strain ε1.
In a conventional polyurethane foam, when either the compressive residual strain ε1 or the wet heat compressive residual strain ε2 is reduced, the other is often increased. Therefore, the conventional polyurethane foam often has a strain ratio ε2/ε1 of 1.0 or more.
On the other hand, the seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention is small in both ε1 and ε2. In particular, the polyurethane foam according to the present invention is characterized in that the wet heat compressive residual strain ε2 is smaller than the compressive residual strain ε1. As a result, the ε2/ε1 is less than 1.0. When the manufacturing conditions are further optimized, the ε2/ε1 is 0.03 or more and 0.8 or less.
The “25% hardness” refers to a value (diameter of a pressurizing plate: 200 mm) as measured in accordance with JIS K 6400-2, Method D.
Conventionally, soft polyurethane foams having good vibration absorbability often have a high density. However, when such a soft polyurethane foam is used as a seat pad, the vehicle weight is increased in some cases. In order to solve this problem, when the density of the soft polyurethane foam is simply reduced, the hardness of the foam reduces. As a result, the repulsion elasticity becomes excessively small, and the cushioning property is deteriorated in some cases.
On the other hand, the seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention has a moderate hardness. When the manufacturing conditions are optimized, the 25% hardness of the polyurethane foam is 150 N or more. When the manufacturing conditions are further optimized, the 25% hardness is 170 N or more, or 190 N or more. Due to this hardness, even if the seat pad is thinner than the conventional one, the seat pad is excellent in vibration absorbability, has good seating comfort, and can be reduced in weight.
On the other hand, too high a 25% hardness of the polyurethane foam may deteriorate the seating comfort of the seat. Therefore, the 25% hardness is preferably 350 N or less.
The “hysteresis loss” refers to a value as measured in accordance with JIS K 6400-2, Method E.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention exhibits a moderate hysteresis loss. When the manufacturing conditions are optimized, the hysteresis loss of the polyurethane foam is 5 to 30%.
The “deflection coefficient” refers to a value as measured in accordance with JIS K 6400-2:2012. More specifically, the “deflection coefficient” refers to a value (=F65%/F25%) obtained by dividing a force (F65%) at 65% compression by a force (F25%) at 25% compression when compression is performed, at a constant speed, up to 75% after 75% preliminary compression.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention has a small deflection coefficient. When the manufacturing conditions are optimized, the deflection coefficient of the polyurethane foam is 2.8 or less. When the manufacturing conditions are further optimized, the deflection coefficient is 2.7 or less, 2.6 or less, or 2.5 or less.
The “stress relaxation” refers to a value (load: 196 N, 5 min) as measured in accordance with JIS K 6400-2.
The seat pad according to the present invention is composed of a polyurethane foam obtained by reacting a raw material mixture satisfying predetermined conditions. Therefore, the polyurethane foam according to the present invention has low stress relaxation. When the manufacturing conditions are optimized, the stress relaxation of the polyurethane foam is 2 to 20%.
The “density” refers to a value as measured in accordance with JIS K 7222.
In order to reduce the weight of the seat pad, the density of the polyurethane foam is preferably 68 kg/m3 or less. The density is more preferably 66 kg/m3 or less.
The polyurethane foam constituting the seat pad is obtained by:
Usually, the raw material mixture further contains a crosslinking agent, a foaming agent, and a catalyst.
The polyol component is one of the main raw materials for the polyurethane foam.
In the present invention, the polyol component contains a polyether polyol A having
The polyol component may contain one kind of polyether polyol A satisfying such conditions, or may contain two or more kinds of polyether polyols A satisfying such conditions,
The polyol component may further contain a polyether polyol B having
The polyol component may contain one kind of polyether polyol B satisfying such conditions, or may contain two or more kinds of polyether polyols B satisfying such conditions.
The “EO content rate (mol %)” of the polyether polyol A refers to a proportion of the number of moles of an ethylene oxide (EO) unit to the total number of moles of alkylene oxide units contained in the polyether polyol A.
The polyether polyol A may contain an alkylene oxide unit other than the EO unit. In this case, the kind of alkylene oxide unit other than the EO unit is not particularly limited, but is preferably a propylene oxide (PO) unit.
The EO content rate of the polyether polyol A mainly affects the wet heat compressive residual strain ε2. In general, the ε2 is smaller as the EO content rate is higher. This is considered to be because
In order to obtain such an effect, the EO content rate of the polyether polyol A is preferably 50.0 mol % or more. The EO content rate is more preferably 60.0 mol % or more, 70.0 mol % or more, 80.0 mol % or more, or 90.0 mol % or more. The EO content rate of the polyether polyol A may be 100.0 mol %.
The number of functional groups of the polyether polyol A affects the compressive residual strain ε1. In general, the ε1 is smaller as the number of functional groups increases. This is considered to be because, as the number of functional groups is larger, the number of crosslinking points increases, and the rigidity of the polyurethane foam increases. In order to obtain such an effect, the number of functional groups of the polyether polyol A is preferably 2.0 or more. The number of functional groups is more preferably 2.1 or more, or 2.2 or more.
On the other hand, an excessive number of functional groups of the polyether polyol A may excessively increase the hardness of the polyurethane foam. Therefore, the number of functional groups is preferably 3.0 or less. The number of functional groups is more preferably 2.9 or less, or 2.8 or less.
Too small a weight average molecular weight of the polyether polyol A may deteriorate the compressive residual strain ε1 and/or the wet heat compressive residual strain ε2. Therefore, the weight average molecular weight is preferably 3000 or more. The weight average molecular weight is more preferably 4000 or more, or 5000 or more.
On the other hand, too large a weight average molecular weight of the polyether polyol A may excessively increase the viscosity of the raw material mixture, leading to deterioration in manufacturability. In addition, the reactivity of the raw material mixture may be reduced, and the tear strength of the polyurethane foam may be reduced. Therefore, the weight average molecular weight is preferably 12000 or less. The weight average molecular weight is more preferably 10000 or less, or 8000 or less.
Too large a hydroxyl value of the polyether polyol A may deteriorate seating comfort of a seat pad. Therefore, the hydroxyl value is preferably 70 mgKOH/g or less. The hydroxyl value is more preferably 60 mgKOH/g or less, or 55 mgKOH/g or less.
On the other hand, too small a hydroxyl value of the polyether polyol A may excessively harden the polyurethane foam, thereby making it impossible to maintain good seating comfort when the polyurethane foam is used as a seat pad. Therefore, the hydroxyl value is preferably 10 mgKOH/g or more. The hydroxyl value is more preferably 15 mgKOH/g or more, or 20 mgKOH/g or more.
The “EO content rate (mol %)” of the polyether polyol B refers to a proportion of the number of moles of an ethylene oxide (EO) unit to the total number of moles of alkylene oxide units contained in the polyether polyol B.
The polyether polyol B may contain an alkylene oxide unit other than the EO unit. In this case, the kind of alkylene oxide unit other than the EO unit is not particularly limited, but is preferably a propylene oxide (PO) unit.
Too high an EO content rate of the polyether polyol B may reduce the reactivity of the raw material mixture. In addition, the foam state and the air permeability of the foam may deteriorate. Therefore, the EO content rate is preferably 30 mol % or less. The EO content rate is more preferably 20 mol % or less, 10 mol % or less, or 5 mol % or less. The EO content rate may be zero.
The number of functional groups of the polyether polyol B has only to be 2.0 or more.
However, too large the number of functional groups of the polyether polyol B may reduce elongation of the polyurethane foam. Therefore, the number of functional groups is preferably 4.0 or less. The number of functional groups is more preferably 3.8 or less, or 3.6 or less.
The weight average molecular weight of the polyether polyol B is not particularly limited, and an optimum value can be selected according to the purpose. In general, too small a weight average molecular weight of the polyether polyol B may impair the elongation percentage and flexibility of the polyurethane foam. Therefore, the weight average molecular weight is preferably 1000 or more. The weight average molecular weight is more preferably 2000 or more, or 3000 or more.
On the other hand, too large a weight average molecular weight of the polyether polyol B may excessively increase the viscosity of the raw material mixture, leading to deterioration in manufacturability. Therefore, the weight average molecular weight is preferably 12000 or less. The weight average molecular weight is more preferably 10000 or less, or 8000 or less.
The polyisocyanate component is the other one of the main raw materials for the polyurethane foam.
In the present invention, the polyisocyanate component contains at least carbodiimide-modified MDI. The polyisocyanate component may contain only carbodiimide-modified MDI, or may further contain a polyisocyanate (hereinafter, this is also referred to as “polyisocyanate B”) other than the carbodiimide-modified MDI.
The carbodiimide (—N═C═N—)-modified MDI is composed of a product produced by condensation, with CO2 generation, between —NCO groups of diphenylmethane diisocyanate (MDI) in the presence of a catalyst.
The use of the carbodiimide-modified MDI as the polyisocyanate component increases the cushioning property of the polyurethane foam, increases the elasticity, decreases the hysteresis loss, decreases the deflection coefficient, or decreases the stress relaxation.
In the present invention, the type of polyisocyanate B is not particularly limited, and an optimum polyisocyanate B can be selected according to the purpose.
Specific examples of the polyisocyanate B include bifunctional aromatic isocyanates, bifunctional alicyclic isocyanates, bifunctional aliphatic isocyanates, and isocyanates having a functionality of more than 2. The polyisocyanate component may contain any one of these polyisocyanates B, or may contain two or more thereof.
Examples of the bifunctional aromatic isocyanate include
Examples of the bifunctional alicyclic isocyanate include
Examples of the bifunctional aliphatic isocyanate include
Examples of the tri- or higher functional isocyanate include
The “NCO group content rate (NCO %)” refers to a proportion of the mass of NCO groups to a total mass of the polyisocyanate component.
The NCO % of the polyisocyanate component is preferably less than 35%, more preferably less than 30%, and still more preferably 29.5% or less.
The raw material mixture may contain a crosslinking agent. The crosslinking agent is preferably a compound having a number of functional groups of at least 3 or more and containing a functional group having an active hydrogen atom (for example, a hydroxyl group, an amino group, or the like). The crosslinking agent may be composed only of a compound having a number of functional groups of 3 or more, or may further contain a compound having a number of functional groups of 2 in addition to the compound having a number of functional groups of 3 or more.
The number of functional groups of the crosslinking agent affects the compressive residual strain ε1. In order to obtain a polyurethane foam having a small compressive residual strain ε1, the number of functional groups of the crosslinking agent is preferably 3 or more.
On the other hand, an excessively large number of functional groups of the crosslinking agent may excessively increase the hardness of the polyurethane foam. Therefore, the number of functional groups of the crosslinking agent is preferably 6 or less.
The molecular weight of the crosslinking agent is not particularly limited, and an optimum value can be selected according to the purpose. The molecular weight of the crosslinking agent is preferably 1000 or less, 700 or less, or 500 or less.
The molecular weight of the crosslinking agent is preferably 60 or more, 90 or more, or 120 or more.
Examples of the crosslinking agent include glycerin, diethanolamine (DEA), and polyfunctional polyol.
The raw material mixture may contain any one of these crosslinking agents, or may contain two or more thereof.
The “foaming agent” refers to an additive for generating bubbles in the raw material mixture in the process of resinizing the liquid raw material mixture.
In the present invention, the foaming agent may be either
Examples of the physical foaming agent include
Examples of the chemical foaming agent include
The raw material mixture may contain any one of these foaming agents, or may contain two or more thereof.
Among them, the foaming agent is preferably water. When water is used as the foaming agent, CO2 gas generated by reaction between water and an isocyanate group promotes foaming. The heat of reaction between water and an isocyanate group accelerates curing of the resin.
The “catalyst” refers to a catalyst having a large action of accelerating the resinification reaction and/or a catalyst having a large action of accelerating the foaming reaction.
When a chemical foaming agent (water) is not used as the foaming agent, it is preferable to use a catalyst having a large action of accelerating the resinification reaction.
Examples of the catalyst include an amine-based catalyst and a metal catalyst. The amine-based catalyst is a catalyst having a large action of accelerating both the resinification reaction and the foaming reaction. The metal catalyst is a catalyst having a large action of accelerating the resinification reaction. The raw material mixture may contain any one of these catalysts, or may contain two or more thereof.
Examples of the amine-based catalyst include
Examples of the metal catalyst include
The raw material mixture may further contain one or more of the following sub-raw materials in addition to the main raw materials described above. Specific examples of the sub-raw material are as follows.
The “foam stabilizer” refers to an additive having an action of uniformizing the size and distribution of bubbles.
The addition of the foam stabilizer to the raw material mixture can provide a polyurethane foam having bubbles uniform in size and distribution. Examples of the foam stabilizer include silicone-based foam stabilizers, fluorine-containing compound-based foam stabilizers, and known surfactants.
The “flame retardant” refers to an additive having an action of making the polyurethane foam flame-retardant.
Examples of the flame retardant include halogen-based flame retardants, phosphorus-based flame retardants, metal hydroxide-based flame retardants, and antimony-based flame retardants.
The “blending amount (parts by mass) of the polyether polyol A” refers to a total mass of the polyether polyol A in the polyol component when the total mass of the polyol component is 100.
In general, as the blending amount of the polyether polyol A is larger, the wet heat compressive residual strain ε2 of the polyurethane foam decreases. In order to obtain such an effect, the blending amount of the polyether polyol A is preferably 50 parts by mass or more. The blending amount is more preferably 60 parts by mass or more, or 70 parts by mass or more.
The blending amount of the polyether polyol A may be 100 parts by mass. However, an excessive blending amount of the polyether polyol A may deteriorate moldability of the foam. Therefore, the blending amount of the polyether polyol A is preferably 90 parts by mass or less.
The “content (mass %) of the carbodiimide-modified MDI” refers to a proportion of the mass of the carbodiimide-modified MDI to the total mass of the polyisocyanate component.
In general, as the content of the carbodiimide-modified MDI is higher, the stress relaxation and hysteresis loss of the polyurethane foam decrease. In order to obtain such an effect, the content of the carbodiimide-modified MDI is preferably 50 mass % or more. The content is more preferably 60 mass % or more, or 70 mass % or more.
The content of the carbodiimide-modified MDI may be 100 mass %. The content of the carbodiimide-modified MDI is preferably 90 mass % or less, or 80 mass % or less.
An NCO content rate of the carbodiimide-modified MDI is preferably 40% or less, 35% or less, or 32% or less, and particularly preferably 30% or less. The NCO content rate is preferably 15% or more, 20% or more, 25% or more, or 27% or more.
The “blending amount (parts by mass) of the crosslinking agent A” refers to a mass of the crosslinking agent A when the total mass of the polyol components is 100.
In general, as the content of the crosslinking agent A is higher, the compressive residual strain ε1 of the polyurethane foam decreases. In order to obtain such an effect, the blending amount of the crosslinking agent A is preferably more than 0 parts by mass. The blending amount is more preferably 1.0 parts by mass or more, or 2.0 parts by mass or more.
On the other hand, an excessive blending amount of the crosslinking agent A may excessively increase the hardness of the polyurethane foam. Therefore, the blending amount of the crosslinking agent A is preferably 10 parts by mass or less. The blending amount is more preferably 8 parts by mass or less, or 6 parts by mass or less.
The “blending amount (parts by mass) of the polyether polyol B” refers to a total mass of the polyether polyol B in the polyol component when the total mass of the polyol component is 100.
In general, an excessive blending amount of the polyether polyol B relatively decreases the blending amount of the polyether polyol A. As a result, the wet heat compressive residual strain ε2 of the polyurethane foam may increase. Therefore, the blending amount of the polyether polyol B is preferably less than 50 parts by mass. The blending amount is more preferably 40 parts by mass or less, or 30 parts by mass or less.
The “isocyanate index” refers to a value obtained by multiplying a ratio of an equivalent of an isocyanate group of the polyisocyanate in the raw material mixture to an equivalent of an active hydrogen group in the raw material mixture by 100.
In the present invention, the isocyanate index is not particularly limited, and an optimum value can be selected according to the purpose. Generally, as the isocyanate index is larger, the compressive residual strain ε1 of the polyurethane foam decreases due to the increased number of crosslinking points. Therefore, the isocyanate index is preferably 90 or more. The isocyanate index is more preferably 95 or more.
On the other hand, too large an isocyanate index may excessively increase the hardness of the polyurethane foam. Therefore, the isocyanate index is preferably 115 or less.
In the present invention, the blending amount of the sub-raw material is not particularly limited, and an optimum blending amount can be selected according to the purpose.
As the foaming in the method for producing a polyurethane foam according to the present invention, either slab foaming or mold foaming can be employed.
The slab foaming is a method in which a composition for producing a polyurethane foam (raw materials for a polyurethane foam) is mixed, discharged onto a belt conveyor, and foamed at normal temperature under atmospheric pressure.
On the other hand, the mold foaming is a method in which raw materials for producing a polyurethane foam (raw materials for a polyurethane foam) are mixed and injected into a cavity of a mold (die), and foamed into a cavity shape. The mold foaming is preferable in that a polyurethane foam having a shape close to the shape of the seat pad is obtained.
In the case of mold molding, the polyisocyanate preferably has a low viscosity, and, for example, a prepolymer type polyisocyanate is not preferable.
In the case of manufacturing a polyurethane foam, the use of a raw material mixture containing a polyether polyol A and carbodiimide-modified MDI which satisfy predetermined conditions provides a polyurethane foam small in both compressive residual strain ε1 and wet heat compressive residual strain ε2. Further, optimization of manufacturing conditions provides a polyurethane foam having a 25% hardness of 150 N or more.
It is considered that the compressive residual strain ε1 is decreased because the rigidity of the polyurethane foam is increased due to the use of a polyether polyol A having a large number of functional groups and a large weight average molecular weight.
It is considered that the wet heat compressive residual strain ε2 is decreased because the use of a polyether polyol A having a high EO content rate increases water absorbability so that the restoring force by the absorbed water is increased.
Furthermore, it is considered that the hardness is moderately increased because the number of crosslinking points is increased due to the use of a polyether polyol A having a large number of functional groups.
A polyether polyol, a crosslinking agent, a foaming agent, a catalyst, a foam stabilizer, and a flame retardant were blended at a predetermined ratio to obtain a mixed liquid (hereinafter, also referred to as “component A”).
In addition, TDI-80, polymeric MDI, and MDI (NCO content rate: 29%, carbodiimide-modified MDI content: 75 mass %) containing carbodiimide-modified MDI were blended at a predetermined ratio to obtain a mixed liquid (hereinafter, also referred to as “component B”).
Further, the component A and the component B were mixed so that the isocyanate index reached a predetermined value to obtain a raw material mixture. Table 1 shows the compositions of the component A and the component B.
Examples 1 and 2 are examples in which a mixture of
Example 3 is an example in which only polyether polyol 4 (molecular weight: 3500, number of functional groups: 3, EO content rate: 75 mol %) was used as the polyether polyol A.
The obtained raw material mixture was injected into a die of 400 mm×400 mm×100 mm, and foamed and cured at a die temperature of about 60° C. The curing time was set to 5 minutes.
A skin layer was removed from the obtained foam to prepare a sample for core density measurement. The obtained sample was used to measure the core density in accordance with JIS K 7222.
The 25% hardness was measured in accordance with JIS K 6400-2 Method D.
The hysteresis loss was measured in accordance with JIS K 6400-2 Method E.
The deflection coefficient was measured in accordance with JIS K 6400-2 Method E. The deflection coefficient was determined by dividing 65% compressive load by 25% compressive load.
The stress relaxation was determined in accordance with JIS K 6400-4. The load was set to 196 N, and the pressurization time was set to 5 minutes.
The compressive residual strain ε1 was measured in accordance with JIS K 6400-4. The test temperature was set to 70° C., the test time was set to 22 hours, and the compression rate was set to 50%.
The wet heat compressive residual strain ε2 was measured in accordance with JIS K 6400-4. The test temperature was set to 50° C., the humidity was set to 95% RH, the test time was set to 22 hours, and the compression rate was set to 50%.
The results are shown in Table 2. Table 2 also shows the test piece size and the evaluation test method of each physical property value. The following matters are seen from Table 2.
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments at all, and various modifications can be made without departing from the gist of the present invention.
The seat pad according to the present invention can be used as a seat pad for seats of automobiles, aircraft, and railway vehicles, a sofa, a mattress, and cushioning materials therefor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-165098 | Oct 2022 | JP | national |
| 2023-020615 | Feb 2023 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/036682 | 10/10/2023 | WO |
