JP2019014848A - Cushioning material - Google Patents

Abstract

To provide a cushioning material excellent in durability with time.SOLUTION: There is provided a cushioning material having a urethane foam containing a hard segment and a soft segment, in which the urethane foam is a reaction cured article formed by using an isocyanate component of a diphenylmethane diisocyanate-based compound, the urethane foam has spin-spin relaxation time (T2) of the hard segment of 20 μsec. to 40 μsec. in a Hsolid pulse NMR measurement and volume abundance ratio of the hard segment of 5% to 40%.SELECTED DRAWING: None

Description

  The present disclosure relates to a cushion material.

  Urethane foam is used in various applications (for example, see Patent Documents 1 to 4).

For example, in Patent Document 1, diphenylmethane diisocyanate polyisocyanate (A) and a polyol component (B) are mixed in the presence of a catalyst (C), a foam stabilizer (D), and a foaming agent (E), and gold A flexible polyurethane foam for automobile seat cushions is disclosed by pouring into a mold. And this flexible polyurethane foam for seat cushions for automobiles is disclosed that the difference between the core density and the total density of the foam is 5 kg / m ³ or less.
In Patent Document 2, diphenylmethane diisocyanate (A) having a 2,4′-diphenylmethane diisocyanate content of 55 to 90% by mass, an oxyethylene content of 1 to 40% by mass, an average hydroxyl equivalent of 700 to 2500, and a nominal average A polyisocyanate composition containing a reaction product with a polyoxyethylene polyoxypropylene polyol (B) having 2 to 6 functional groups is disclosed. And it is disclosed that this reaction product has an isocyanate group content of 15 to 30% by mass.

Patent Document 3 discloses a polishing pad comprising a polyurethane resin-made polishing layer formed by the reaction of an isocyanate group-containing compound and a polyamine compound, and in which cells are formed substantially evenly on the polishing layer. In this polishing pad, the polyurethane resin constituting the polishing layer has a crystal phase formed of a hard segment, an amorphous phase formed of a soft segment, and an interface between the crystal phase and the amorphous phase. Having a phase. Furthermore, when the component ratio of the interface phase obtained from the free induction decay signal by the pulse nuclear magnetic resonance method in an environment of 120 ° C. is RI (%) and the spin-spin relaxation time is T2I (μs), P = 22500-160 · RI-21 · T2I It is disclosed that the P value obtained is in the range of 6000-7500.
Patent Document 4 discloses a polishing pad having a polishing layer made of urethane foam containing hard segments and soft segments. And this polishing pad is disclosed that the abundance ratio of the hard segment in the urethane foam at 24 ° C. by pulse NMR measurement is 61.9% or more and 68.8% or less.

JP 2010-280855 A JP 2008-247996 A Japanese Patent No. 5242322 Japanese Patent No. 5846714

  An object of the present disclosure is to provide a cushion material excellent in durability over time, a cushion material for a vehicle seat, and a cushion material for a vehicle seat.

  Means for solving the above problems include the following aspects.

<1> It has urethane foam including a hard segment and a soft segment,
The foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound,
The foamed urethane is a cushioning material having a hard segment spin-spin relaxation time (T2) of 20 μsec or more and 40 μsec or less and a volume ratio of the hard segment of 5% or more and 40% or less in H ¹ solid-state pulse NMR measurement.
<2> Having foamed urethane containing a hard segment and a soft segment,
The foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound,
A cushioning material in which the urethane foam has a compression set of 1% or less after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95%.
<3> The cushion material according to <1> or <2>, wherein the isocyanate component is an isocyanate terminal-modified polyisocyanate obtained by reacting a mixture of monomeric diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate with a part of the polyol component.
<4> The cushion material according to any one of <1> to <3>, wherein the cushion material is a cushion material for a vehicle seat.
<5> The cushion material according to any one of <1> to <4>, wherein the cushion material is a cushion material for a vehicle seat.

  According to the cushion material of the present disclosure, a cushion material excellent in durability over time, a cushion material for a vehicle seat, and a cushion material for a vehicle seat are provided.

  Hereinafter, an embodiment which is an example of the cushion material of the present disclosure will be described.

The cushioning material of this indication has urethane foam containing a hard segment and a soft segment. This foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound. The urethane foam has the characteristics that the hard segment spin-spin relaxation time (T2) is 20 μsec or more and 40 μsec or less and the hard segment volume existence ratio is 5% or more and 40% or less in H ¹ solid-state pulse NMR measurement. Have. That is, the hard segment of this urethane foam has a spin-spin relaxation time (T2) of 20 μsec to 40 μsec and a volume ratio of 5% to 40% in H ¹ solid-state pulse NMR measurement.

  Moreover, the cushion material of this indication has foaming urethane containing a hard segment and a soft segment. This foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound. The urethane foam has a characteristic of a compression set of 1% or less after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95%.

  Conventionally, urethane foam has been applied to various cushion materials such as cushion materials for vehicle seats such as vehicle seats, cushion materials for furniture, cushion materials for office chairs, and cushion materials for bedding mattresses. It has been.

  The cushion material has durability over time as one of required characteristics. In particular, when urethane foam is applied to a cushion material for a vehicle seat, the vehicle seat cushion material is required to have durability over time. If the cushion material has low durability over time, the cushion material is greatly affected by the holding properties of various physical properties related to riding comfort (that is, comfort) such as vibration absorption, rebound resilience, and load deflection characteristics.

For example, the urethane foam used as seat including a cushion material of a vehicle seat for a vehicle, in a suitable expansion ratio (approximately 60 kg / m ³ before and after), while maintaining a flexible cushioning, required to improve the comfort Is done. In order to meet this requirement, urethane foam is increasing the abundance ratio of hard segments in the urethane foam.
The hard segment has a high melting point or a high glass transition temperature. For this reason, the hard segment contributes to high modulus and high strength. The hard segment is a part that expresses physical properties and strength over time from the initial stage of urethane foam (immediately after the production of urethane foam).

  When the composition for forming the hard segment is a urea bond aggregate, a hydrogen bond (non-covalent bond) is formed at the interface between each urea bond, so that the initial physical properties immediately after the production of the urethane foam are good. However, under wet heat compression that is used for a long time, such as under the occupant's bottom, moisture intervenes in hydrogen bonding, and each of the urea-bonded aggregates (part of the hard segment) subjected to local shear compression It is considered that slip deformation tends to occur at the interface between urea bonds.

  On the other hand, the soft segment has a glass transition temperature lower than room temperature. For this reason, the soft segment contributes to high elongation and elastic recovery. The soft segment is a part that expresses the flexibility of the urethane foam.

  The durability of the cushioning material over time reflects, for example, the realistic use environment of the vehicle seat, and as a reliability test over time under the condition of applying wet heat simultaneously with the compression load, wet heat compression set (temperature 50 A compression set after 50% compression for 22 hours under the conditions of ° C. and 95% relative humidity is known. By measuring the final thickness change (permanent strain) of the cushioning material, the wet heat compression set can be expected to change in vibration absorption, rebound resilience, load deflection characteristics (bottom sensation), and the like. That is, the wet heat compression set is an index that can be used to know the effect on comfort when applied to a vehicle seat.

  It is desirable that the wet heat compression set is small as an index representing the durability of the vehicle seat cushion material over time.

For example, the flexible polyurethane foam for automobile seat cushion disclosed in Patent Document 1 has low durability over time, and further improvement has been demanded.
Further, the urethane foam molded from the polyisocyanate composition disclosed in Patent Document 2 is applied to, for example, a cushion material for furniture, a cushion material for vehicle seats such as automobiles and railways, and a cushion material for bedding mattresses. In some cases, durability over time was low, and further improvement was demanded. In particular, when the polyurethane disclosed in Patent Document 2 is applied to a cushion material for a vehicle seat, due to low durability over time, comfort has not been sufficiently satisfied, There has been a demand for further improvement in durability over time.
Thus, the cushion material using the conventional urethane foam has been required to further improve durability over time.

  On the other hand, the urethane foam disclosed in Patent Document 3 and Patent Document 4 is used for a polishing pad. The urethane foam used for these polishing pads does not have the characteristics required as a cushioning material, and is a material that is not suitable for use as a cushioning material (particularly a cushioning material for a vehicle seat).

Here, the conventional urethane foam is considered to have a high proportion of hard segments (for example, a form of a large aggregate structure in which urea bonds are dense) in the foamed resin (parts forming a skeleton and a film) of the urethane foam. It is done.
When conventional H ¹ pulse NMR measurement is performed on urethane foam at 24 ° C. in vacuum, spin-spin relaxation of hard segments obtained by H ¹ pulse NMR (nuclear magnetic resonance) measurement in vacuum at 24 ° C. The time (T2) is less than 20 μsec. At this time, it is considered that the conventional urethane foam forms a large aggregate structure in which urea bonds are dense (for example, an aggregate structure of urea bonds having a diameter of 10 nm or more). In addition, as the volume ratio of the hard segment is increased, it is considered that the structure has a higher ratio of the urea bond aggregate structure.
In other words, when the spin-spin relaxation time (T2) of the hard segment of the urethane foam is less than 20 μsec and the volume existence ratio of the hard segment is large, a structure having a large number of large aggregate structures with dense urea bonds is formed. Presumed to be.

  When a shear load is applied to the conventional urethane foam having this structure, it is considered that a large positional shift occurs at the hydrogen bond (non-covalent bond) interface between urea bonds. As a result, each aggregate structure undergoes permanent deformation accompanied by shear deformation, and it is considered that each cell resin composed of the aggregate structure in which such permanent deformation has occurred also has permanent deformation. Therefore, it is estimated that the conventional cushioning material using urethane foam has low durability over time.

On the other hand, the cushion material of the present disclosure is formed from a specific foamed urethane, and has a hard segment spin-spin relaxation time (T2) in H ¹ solid-state pulse NMR measurement at 24 ° C. in vacuum. It is 20 μsec or more and 40 μsec or less, and the volume existence ratio is 5% or more and 40% or less. For this reason, there are few large aggregate structures with dense urea bonds (that is, hydrogen bonds between urea bonds (low noncovalent bonds) and a small number of urea bond aggregates, which are simple structures. As a result, it is considered that even when a shear load is applied to the cushion material of the present disclosure, the occurrence of shear set is suppressed. It is estimated that the material has an element that reduces durability over time, and is excellent in durability over time.

  Further, the cushion material of the present disclosure is formed from a specific foamed urethane, and is subjected to compression set (wet heat compression) after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95%. Permanent strain) is 1% or less. The wet heat compression set of the cushion material using the conventional urethane foam exceeds 5%, for example. Therefore, the cushion material of the present disclosure is superior in durability over time than the cushion material using the conventional urethane foam. ing.

(H ¹ solid-state pulse NMR measurement)
Here, the spin-spin relaxation time (T2) and volume abundance ratio in the H ¹ solid-state pulse NMR (Nuclear Magnetic Resonance) measurement will be described.

First, the H ¹ solid pulse NMR measurement will be described. In the present specification, the H ¹ solid-state pulse NMR measurement is a measurement performed at 24 ° C. in a vacuum using a cushion material to be measured as a test piece after vacuum drying at room temperature all day and night and a vacuum sealed tube. Specific measurement conditions are shown below.

-Measurement conditions-
Measuring device: JNM-MU25 (resonance frequency 25 MHz) manufactured by JEOL
Measuring method: Solid echo method Measuring temperature: 24 ° C
Pulse width: 90 ° pulse, 2.3 μs
Repeat time: 4 sec
Integration count: 32 times (foamed sample)
The analysis results (spin-spin relaxation time (T2) and volume existence ratio of the hard segment) are based on the assumption that the value of Variance dispersion is 25 or less. Variance variance indicates the degree of data dispersion, and is represented by the average of the squares of deviations.

In the H ¹ solid-state pulse NMR measurement, the amount of the component of the measurement object can be evaluated using the difference in relaxation time.
When H ¹ solid-state pulse NMR measurement is performed on the measurement object, an FID signal (free induction decay) is obtained as a response to the pulse. The initial value of the FID signal is proportional to the number of protons in the measurement sample. For example, when the measurement object has a plurality of components such as a hard segment and a soft segment, the FID signal is the sum of the response signals of the respective components. If there is a difference in mobility depending on the components, the spin-spin relaxation time (T2) is different. Therefore, by separating the spin-spin relaxation time (T2), the relaxation time of each component and the ratio (volume existence ratio) of each component can be obtained. As the component mobility decreases, the spin-spin relaxation time (T2) decreases. As the mobility increases, the spin-spin relaxation time (T2) increases. That is, the hard component has a shorter spin-spin relaxation time (T2), and the softer component has a longer spin-spin relaxation time (T2).

When foamed urethane having a hard segment and a soft segment is measured, in the H ¹ solid-state pulse NMR measurement, there is a difference in mobility between the hard segment and the soft segment, so the spin-spin relaxation time (T2) of the two is different. . The hard segment has a short spin-spin relaxation time (T2), and the soft segment has a long spin-spin relaxation time (T2). That is, the spin-spin relaxation time (T2) becomes shorter as the urea bond aggregate structure is formed, and the spin-spin relaxation time (T2) becomes longer as the urea bond aggregate structure is suppressed. Become.
In addition, the spin-spin relaxation time (T2) is shorter as the volume ratio of the hard segment is larger (that is, the urea bond aggregate structure is formed).

From the above, in the H ¹ solid-state pulse NMR measurement in vacuum at 24 ° C., the spin-spin relaxation time (T2) of the hard segment is 20 μsec or more and 40 μsec or less. This is thought to mean that there are few hydrogen bonds between urea bonds in the structure (that is, there are few large aggregate structures with dense urea bonds). At the same time, the volume ratio of the hard segment being 5% or more and 40% or less indicates that the existence ratio of hydrogen bonds between urea bonds in the aggregate structure of urea bonds is small (that is, the aggregate structure with dense urea bonds). It is thought that the structure is suppressed).

A preferable lower limit value of the spin-spin relaxation time (T2) of the hard segment is 21 μsec or more, more preferably 22 μsec or more. Moreover, the preferable upper limit of the spin-spin relaxation time (T2) of the hard segment is 39 μsec or less, more preferably 38 μsec or less.
On the other hand, the preferable lower limit of the volume existence ratio of the hard segment is 10% or more, more preferably 19% or more. Moreover, the upper limit with a preferable volume ratio of a hard segment is 38% or less, More preferably, it is 35% or less.

(Heat heat compression set)
Next, the wet heat compression set will be described.
In this specification, the wet heat compression set is a measurement of compression set after 50% compression for 22 hours under the conditions of a temperature of 50 ° C. and a relative humidity of 95%.
Specifically, a cushion material to be measured is cut into a thickness of 40 mm ± 1 mm and used as a test piece. The thickness (t0) of this test piece is measured, compressed and fixed to 50% of the thickness of the test piece, and left in a high-humidity thermostatic chamber at 50 ° C. and 95% relative humidity for 22 hours. Thereafter, the fixed test piece is taken out, and the thickness (t1) of the test piece after 30 minutes is measured. Then, let the value calculated | required by the following formula be the value of wet heat compression set.
(Formula) Wet heat compression set (%) = {(t0−t1) / t0} × 100

The cushion material of the present disclosure has a compression set of 1% or less after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95%. Preferably it is 0.8% or less, More preferably, it is 0.5% or less.
That the wet heat compression set is 1% or less means that the compression set over time under wet heat conditions is kept low. Therefore, when the cushion material of this indication is applied, for example to the cushion material for vehicles, it shows that the durability (for example, comfort) more stable over time can be obtained over time.
The lower the wet heat compression set, the better the durability over time (for example, comfort). Therefore, the lower limit of the wet heat compression set is preferably 0%, but the lower limit is not particularly limited. Absent.

  Hereinafter, urethane foam which is a material of the cushioning material of the present disclosure will be described. The urethane foam is a urethane foam having open cells.

The cushion material of this indication has foaming urethane formed using the isocyanate ingredient of a diphenylmethane diisocyanate type compound. Specifically, the urethane foam is a reaction cured product obtained by reaction curing of a mixed raw material of an isocyanate component of a diphenylmethane diisocyanate compound, a polyol component, a catalyst, and a foaming agent.
Urethane foam uses a polyisocyanate component obtained by reacting a mixture of monomeric diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate in advance with a part of the polyol, particularly in terms of durability (especially comfort) of the cushion material over time. It is preferable that the reaction cured product is formed.

  Hereinafter, each component for forming foaming urethane is demonstrated.

(Isocyanate component)
First, the isocyanate component of the diphenylmethane diisocyanate compound will be described. Hereinafter, diphenylmethane diisocyanate may be referred to as “MDI”.
The MDI compound is not particularly limited. Examples thereof include pure (pure) diphenylmethane diisocyanate (monomeric MDI), polymeric MDI, isocyanate-terminated polyisocyanate of polymeric MDI, and isocyanate-terminated polyisocyanate including monomeric MDI and polymeric MDI.

  Specifically, for example, 2,2′-diphenylmethane diisocyanate (2,2′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 4,4′-diphenylmethane diisocyanate (4,4 '-MDI), and monomeric MDI of these mixtures; polymeric MDI of polymethylene polyphenylene polyisocyanate; isocyanate-terminated modified polyisocyanate obtained by reacting monomeric MDI with polyol component; isocyanate terminated product obtained by reacting polymeric MDI with polyol component Modified polyisocyanate: Isocyanate-terminated polyisocyanate obtained by reacting a mixture of monomeric MDI and polymeric MDI with a polyol component. These diphenylmethane diisocyanate compounds may be used alone or in combination of two or more.

  Among these, the MDI compound is an isocyanate-terminated polymer obtained by reacting a mixture of a monomeric MDI and a polymeric MDI with a part of a polyol component in that the cushion material is excellent in durability (comfort) with time. An isocyanate (that is, a prepolymer obtained by reacting a mixture of monomeric MDI and polymeric MDI with a part of the polyol component) is more preferable. When this isocyanate terminal-modified polyisocyanate is used, formation of a urea bond aggregate structure is easily suppressed.

  In an isocyanate-terminated polyisocyanate obtained by reacting a mixture of a monomeric MDI and a polymeric MDI with a polyol component, the mixing ratio (mass ratio) of the monomeric MDI and the polymeric MDI is the mass of the monomeric MDI relative to the mass of the polymeric MDI. The ratio (monomeric MDI / polymeric MDI) is preferably in the range of 3/7 to 9/1. More preferably, it is the range of 4/6 or more and 8/2 or less. When the MDI mixing ratio (mass ratio) of the monomeric MDI and the polymeric MDI is in the range of 3/7 or more and 9/1 or less, it is possible to suppress the foam from deviating from the characteristics as the cushioning material. Furthermore, a decrease in moldability is suppressed.

  The isocyanate-terminated polyisocyanate obtained by reacting a mixture of monomeric MDI and polymeric MDI with a polyol component is preferably adjusted to have an NCO content (mass%) of 10 to 30 in the end.

(Polyol component)
The polyol component is not particularly limited. Since the cushion material of the present disclosure may be applied to a vehicle seat (especially a vehicle seat), the polyol component hardly causes hydrolysis (excells in hydrolysis resistance). preferable. Specific examples of ether polyols include PPG (polyoxypropylene polyol, polyoxyethylene polyol, polyoxyethylene polyoxypropylene polyol), PTMG (polytetramethylene ether glycol), and PEG (polyethylene glycol). Those having —O— bonds (ether bonds) such as

  The average molecular weight of the polyol component is preferably in the range of 200 to 10,000 (preferably 600 to 9000) in terms of weight average molecular weight. The weight average molecular weight per number of functional groups of the active hydrogen group (OH group) may be in the range of 200 to 4000 (preferably 300 to 3000).

(catalyst)
The catalyst is not particularly limited, and various urethanization catalysts known in the field of urethane foam used as a cushioning material can be used. For example, triethylamine, triethyldiamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N ′, N ″ -pentamethyldiethylenetriamine, bis- (2-dimethylaminoethyl) ether, triethylenediamine, 1,8-diaza-bicyclo (5,4,0) undecene-7,1,2- Amine-based catalysts of amine compounds such as dimethylimidazole, dimethylethanolamine, N, N-dimethyl-N-hexanolamine; organic acid salts of these amine compounds; stannous octoate; organometallic compounds such as zinc naphthenate . Further, amine-based catalysts having active hydrogen such as N, N-dimethylethanolamine and N, N-diethylethanolamine are also included. These catalysts may be used alone or in combination of two or more.

  The addition amount of the catalyst is preferably 0.01% by mass or more and 10% by mass or less with respect to the polyol component. When it is 0.01% by mass or more, curing shortage is easily suppressed, and when it is 10% by mass or less, a decrease in moldability is suppressed.

(Foaming agent)
The foaming agent is preferably a foaming agent containing water, and is preferably water alone.
The amount of water used as the foaming agent may be appropriately set according to the intended foaming ratio with respect to 100 parts by mass of the polyol component.
When the foaming agent is used in combination with water, examples of the foaming agent other than water include methylene chloride, hydrochlorofluorocarbons (HCFC-123, etc.), hydrofluorocarbons (HFC-245fa, etc.), butane, pentane (cyclopentane). , Isopentane, normal pentane) and the like; organic acids such as formic acid.
Further, as a foaming agent, in addition to a foaming agent containing water, air, nitrogen gas, liquefied carbon dioxide or the like may be mixed and dissolved in a mixed raw material for obtaining foamed urethane. What is necessary is just to set the quantity of foaming agents other than water by the target foaming ratio.

(Other ingredients)
The other components are components (additives) added as necessary. Examples of other components include a crosslinking agent, a colorant, a filler, a flame retardant, an antioxidant, an ultraviolet absorber, an antistatic agent, and a foam stabilizer. When other components are used, these may be used alone or in combination of two or more as required.

  Below, the manufacturing method of the urethane foam used for the cushioning material of this indication is demonstrated.

(Method for producing urethane foam)
It does not specifically limit as a manufacturing method of foaming urethane, The well-known method in the molding method formed in a slabstock method and a type | mold is applicable.
As an example of a preferable method for producing foamed urethane, for example, a first step of preparing an isocyanate component of a diphenylmethane diisocyanate compound, and a second step of molding a raw material obtained by mixing the isocyanate component, the polyol component and the foaming agent are used. The method which has a process is mentioned.

  As the first step, for example, a polyisocyanate component prepared by mixing a mixture of monomeric MDI and polymeric MDI with a part of a polyol in advance (that is, a mixture of monomeric MDI and polymeric MDI is one of the polyol components). It is preferable to prepare an isocyanate-terminated polyisocyanate) reacted with a part. The mixture of the monomeric MDI and the polymeric MDI is preferably 3/7 or more and 9/1 or less (mass ratio) as the mixing ratio of the monomeric MDI / polymeric MDI. Moreover, it is preferable to adjust so that an isocyanate group (NCO group) may finally become 10-30 by NCO content (mass%).

As a 2nd process, it is the process of shape | molding the mixed raw material containing the isocyanate component prepared by the 1st process, a polyol component, and a foaming agent. Hereinafter, the case where it shape | molds by the molding method shape | molded in a type | mold as a 2nd process is demonstrated.
In the second step, the above-mentioned mixed raw material is poured into a mold and foamed at a predetermined temperature in the mold, thereby obtaining a reaction cured product of foamed urethane. The temperature of the mold when foaming is preferably in the range of 30 ° C. or higher and 50 ° C. or lower (preferably lower limit is 35 ° C. or higher, and preferable upper limit is 45 ° C. or lower). When the temperature of the mold is within this range, the spin-spin relaxation time (T2) of the hard segment is 20 μsec or more and 40 μsec or less in the H ¹ solid-state pulse NMR measurement at 24 ° C., and the volume existence ratio of the hard segment is It becomes easy to control in the range of 5% or more and 40% or less. Also, the compression set after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95% can be easily controlled to 1% or less.
When the temperature of the mold during foam molding exceeds 50 ° C. (for example, 60 ° C. or higher), the skin contains a urea-bonded aggregate structure on the surface of the urethane foam in contact with the mold in the mold. A layer is easily formed. For this reason, durability (comfort) over time tends to decrease.

  In the second step, the order of preparing the mixed raw material is that the polyol component is previously mixed with the catalyst and the blowing agent (premix), and then mixed with the isocyanate component prepared in the first step. Also good. Moreover, you may mix the isocyanate component prepared by the 1st process, a catalyst, a foaming agent, and a polyol component, respectively.

  Further, in the method for producing foamed urethane, in all the steps of the first step and the second step, if moisture is present in the production environment of the foamed urethane, the isocyanate component of the diphenylmethane diisocyanate compound reacts with the moisture. Urea bonds are likely to occur. Therefore, it is preferable to manufacture in a nitrogen purge atmosphere in all steps of the manufacturing process of urethane foam. In a nitrogen purge atmosphere, the formation of urea bond aggregate structures is likely to be suppressed.

  In the present specification, the term “process” is not only an independent process, but even if it cannot be clearly distinguished from other processes, if the intended purpose of the process is achieved, Included in this term.

(Use)
The cushion material of the present disclosure can be applied to various cushion materials such as a seat cushion material for a vehicle (ship, aircraft, vehicle, etc.), an office chair cushion material, a bedding mattress cushion material, and a furniture cushion material. In particular, since the cushion material of the present disclosure is excellent in durability (comfort) with time, it is preferably applied as a cushion material for a vehicle seat, and more particularly, is applied to a cushion material for a vehicle seat. Is more preferred. Examples of vehicle seats include, for example, automobiles, railroad seats (seats), and in addition, vehicle seats such as cultivators, tractors, power shovels, hydraulic cranes, excavators, and bicycles. .

  Examples will be described below, but the cushion material of the present disclosure is not limited to these Examples. In the following description, “part” and “%” are all based on mass unless otherwise specified.

<Examples 1-3, Comparative Examples 1-5>
The raw materials shown in Table 1 were blended in the proportions shown in Table 1 so that the molar ratio (NCO INDEX) of (NCO groups / active hydrogen groups) would be the values shown in Table 1 to prepare mixed raw materials. Thereafter, the mixed raw material was poured into a mold and molded at the mold temperature shown in Table 1 to obtain a reaction cured product of urethane foam. In addition, in the preparation process of each raw material, it carried out in nitrogen purge atmosphere.

The materials shown in Table 1 are as shown below.
PPG (A): a polyether polyol having a trifunctional number of active hydrogen groups (OH groups) and a weight average molecular weight of 6000.
Catalyst (a): Triethylenediamine.
Catalyst (b): bis (dimethylaminoethyl) ether.
MDI (E): A modified MDI-based isocyanate composed of monomeric MDI alone and a part of PPG (A).
MDI (B): A modified MDI-based isocyanate in which monomeric MDI and polymeric MDI are previously reacted with a part of PPG (A). The mixing ratio of the monomeric MDI and the polymeric MDI is 8/2 (monomeric MDI / polymeric MDI: mass ratio).
MDI (C): MDI polyisocyanate prepared by blending monomeric MDI and polymeric MDI in advance at a mixing ratio of 6/4 (monomeric MDI / polymeric MDI: mass ratio).
・ TDI (D): Tolylene diisocyanate (TDI)

(Evaluation)
-Pulse NMR measurement-
The foamed urethane obtained in each example was vacuum-dried at room temperature all day and night, and a vacuum sealed tube was used as a test piece. These test pieces were measured in a vacuum at 24 ° C. according to the method described above, and the spin-spin relaxation time (T2) of the hard segment and the volume existence ratio of the hard segment were determined. In Table 1, T2 represents a spin-spin relaxation time (T2).

-Density-
The density of the urethane foam obtained in each example was measured according to JIS K 7222 (2005).

(Evaluation)
-Permanent compression strain-
Regarding the permanent compression set of the urethane foam obtained in each example, the wet heat compression set was measured under the conditions of a temperature of 50 ° C. and a relative humidity of 95%, after 50% compression for 22 hours, The permanent compression strain was calculated according to the method described above.

The foamed urethane obtained in Comparative Examples 1 to 5 has a hard segment spin-spin relaxation time (T2) of less than 20 μsec as measured by H ¹ pulse NMR under vacuum. In addition, the volume existence ratio of the hard segment exceeds 25% and is relatively large. Therefore, the foamed urethane obtained in Comparative Examples 1 to 5 is predicted to be a dense structure in which the urea bond aggregate structure is greatly developed.
In addition, the urethane foams of these comparative examples have a wet heat compression set (50 ° C., 95% RH, 22 hr) exceeding 5%, so when subjected to a load, urea bonds in the urea bond aggregate structure It is considered that the occurrence of shear deviation occurring at the hydrogen bond (noncovalent bond) interface is difficult to be suppressed.
Therefore, when the urethane foam obtained in Comparative Examples 1 to 5 is used as a cushion material for a vehicle seat (particularly a cushion material for a vehicle seat), the thickness change (thinning) of the cushion material, The comfort gradually decreases.

On the other hand, the urethane foams obtained in Examples 1 to 3 have a hard segment spin-spin relaxation time (T2) of 24 μC or higher under a H ¹ pulse NMR measurement under vacuum at 20 μsec or more, and the hard segment Is 40% or less. Therefore, the urethane foam obtained in Examples 1 to 3 is predicted to have a structure in which hydrogen bonds (non-covalent bonds) between urea bonds are suppressed to a small amount.
Further, the urethane foams of these examples have a wet heat compression set (50 ° C., 95% RH, 22 hr) of 1% or less, and therefore, when subjected to a load, a shear set of hydrogen bonds between urea bonds is obtained. It is thought that the occurrence of is suppressed.
Therefore, when the urethane foam obtained in Examples 1 to 3 is used as a vehicle seat cushion material (particularly a vehicle seat cushion material), the thickness change (thinning) of the cushion material is small, and over time. High durability. As a result, the cushion material to which the urethane foam obtained in Examples 1 to 3 is applied is maintained in comfort and excellent in ride comfort.

Claims (5)

Having foamed urethane containing hard and soft segments,
The foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound,
The foamed urethane is a cushioning material having a hard segment spin-spin relaxation time (T2) of 20 μsec or more and 40 μsec or less and a volume ratio of the hard segment of 5% or more and 40% or less in H ¹ solid-state pulse NMR measurement. Having foamed urethane containing hard and soft segments,
The foamed urethane is a reaction cured product formed using an isocyanate component of a diphenylmethane diisocyanate compound,
A cushioning material in which the urethane foam has a compression set of 1% or less after 50% compression for 22 hours under conditions of a temperature of 50 ° C. and a relative humidity of 95%.   The cushion material according to claim 1 or 2, wherein the isocyanate component is an isocyanate terminal-modified polyisocyanate obtained by reacting a mixture of monomeric diphenylmethane diisocyanate and polymeric diphenylmethane diisocyanate and a part of the polyol component.   The cushion material according to any one of claims 1 to 3, wherein the cushion material is a cushion material for a vehicle seat.   The cushion material according to any one of claims 1 to 4, wherein the cushion material is a cushion material for a vehicle seat.