Polyurethane foam, toner sealing member, and cushioning material

Abstract

Provided is a polyurethane foam having high rebound resilience, a cushioning property that is not easily damaged at low temperatures, and low air permeability. A polyurethane foam is obtained from a composition comprising polyols and isocyanates, wherein any one of the following conditions (1) and (2) is satisfied, and the following condition (3) is satisfied. (1) When the total amount of alkylene oxide units in the entire polyol is set to 100% by mass, the content of propylene oxide units is 75% by mass or more. (2) When the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is set to 100% by mass, the content of propylene oxide units is 85% by mass or more. (3) For A obtained by formula (a) and B obtained by formula (b), 2400≦A×B is satisfied.

Description

Technical Field

[0001] The present disclosure relates to a polyurethane foam and a toner sealing member.

[0002] This application is based upon and claims the benefit of priority from Japanese patent application No. 2021-70791, filed on April 20, 2021, the entire contents of which are incorporated herein by reference. Background Art

[0003] Patent Document 1 describes the use of polyurethane foam as a sealing member of a container for toner, and Patent Documents 2 to 4 also describe polyurethane foams having various properties.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-214895.

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2009-265425.

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2012-082273.

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 2002-037828. Summary of the Invention

[0010] Problems to be solved by the invention

[0011] In recent years, polyurethane foams have been required to have various properties, and these requirements have become increasingly stringent. For example, polyurethane foams are required to have high rebound resilience, low cushioning properties that are less likely to be impaired at low temperatures, and low air permeability.

[0012] An object of the present disclosure is to provide a polyurethane foam having high rebound resilience, a cushioning property that is less likely to be impaired at low temperatures, and low air permeability.

[0013] The present disclosure can be implemented in the following forms.

[0014] Means used to solve problems

[0015] [1] A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein:

[0016] Any one of the following conditions (1) and (2) is satisfied, and the following condition (3) is satisfied.

[0017] (1) When the total amount of alkylene oxide units in the entire polyol is 100% by mass, the content of propylene oxide units is 75% by mass or more.

[0018] (2) When the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass, the content of propylene oxide units is 85% by mass or more.

[0019] (3) For A obtained from the following formula (a) and B obtained from the following formula (b),

[0020] Satisfies 2400≦A×B.

[0021] [Formula 1]

[0022]

[0023] [Formula 2]

[0024]

[0025] m1i: the weight average molecular weight of the i-th (i is a natural number where 1≦i≦n) polyol among the n (n is a natural number greater than or equal to 1) polyols included in the polyols;

[0026] f1i: the number of hydroxyl groups per molecule of the i-th (i is a natural number where 1≦i≦n) polyol among the n (n is a natural number greater than or equal to 1) polyols included in the polyols;

[0027] x1i: the amount (parts by mass) of the i-th (i is a natural number where 1≦i≦n) polyol among the n (n is a natural number greater than or equal to 1) polyols included in the polyols;

[0028] y1: the total amount (parts by mass) of n types (n is a natural number greater than or equal to 1) of polyols contained in the polyols;

[0029] f2i: the number of isocyanate groups per molecule of the i-th isocyanate (i is a natural number where 1≦i≦m) among the m isocyanates (m is a natural number greater than or equal to 1) contained in the isocyanates;

[0030] x2i: the amount (parts by mass) of the i-th isocyanate (i is a natural number where 1≦i≦m) among the m isocyanates (m is a natural number greater than or equal to 1) contained in the isocyanates;

[0031] y2: The total amount (parts by mass) of m types (m is a natural number of 1 or greater) of isocyanates contained in the isocyanates.

[0032] Effects of the Invention

[0033] According to the present disclosure, it is possible to provide a polyurethane foam having high rebound resilience, whose cushioning properties are unlikely to be impaired at low temperatures, and low air permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a partial cross-sectional view of a storage container using a toner seal member according to one embodiment.

[0035] Figure 2 is a cross-sectional view of a toner seal member.

[0036] Figure 3 This is a diagram for explaining the method of measuring air permeability.

[0037] Figure 4 This is a SEM photograph of a cross section of the polyurethane foam of Example 5.

[0038] Figure 5 This is a SEM photograph of a cross section of the polyurethane foam of Comparative Example 1.

[0039] Figure 6 This is a SEM photograph of a cross section of the polyurethane foam of Comparative Example 2. DETAILED DESCRIPTION

[0040] Here, preferred examples of the present disclosure are shown.

[0041] [2] A polyurethane foam, wherein the polyol is:

[0042] The polyols as a whole are set to 100 parts by mass, and contain 5 parts by mass or more and 60 parts by mass or less of a polymer polyol having a weight average molecular weight of 1500 to 4500.

[0043] [3] A polyurethane foam, wherein the polyol is:

[0044] The polyester polyol having a weight average molecular weight of 300 to 800 is contained in an amount of 1 part by mass to 20 parts by mass based on 100 parts by mass of the entire polyol.

[0045] [4] A toner seal member comprising the above-mentioned polyurethane foam.

[0046] The present disclosure is described in detail below. In addition, in this specification, when "to" is used to describe a numerical range, unless otherwise specified, both the lower limit and the upper limit are included. For example, a description such as "10 to 20" includes both "10" as the lower limit and "20" as the upper limit. In other words, "10 to 20" has the same meaning as "10 or more and 20 or less."

[0047] 1. Polyurethane foam

[0048] The polyurethane foam is obtained from a composition containing polyols and isocyanates. The polyurethane foam satisfies any one of the above conditions (1) and (2) and also satisfies the above condition (3).

[0049] In the following description, the alkylene oxide unit may be referred to as an AO (alkylene oxide) unit, the propylene oxide unit may be referred to as a PO (propylene oxide) unit, the content of the propylene oxide unit when the total amount of the alkylene oxide units is set to 100% by mass is referred to as the PO content, and the content of the ethylene oxide unit when the total amount of the alkylene oxide units is set to 100% by mass is referred to as the EO (ethylene oxide) content.

[0050] [Polyols]

[0051] The polyols are not particularly limited as long as they satisfy the above-mentioned conditions. As the polyols, it is preferable to use polyether polyols, polymer polyols, and polyester polyols together.

[0052] The polyether polyol preferably uses a polyether polyol A containing only PO units as AO units and a polyether polyol B containing PO units and EO units as AO units.

[0053] The polyether polyol A preferably has a weight average molecular weight of 1500 to 4500 (preferably 2000 to 4000) and a functional group number of 3. The PO content of the polyether polyol A is 100%. The use of polyether polyol A can improve the high resilience and low-temperature cushioning properties of the polyurethane foam.

[0054] There are no particular limitations on the content of polyether polyol A. The content of polyether polyol A is preferably 1 part by mass or more and 60 parts by mass or less, and more preferably 5 parts by mass or more and 40 parts by mass or less, based on 100 parts by mass of the entire polyols.

[0055] Polyether polyol B more preferably has a weight-average molecular weight of 1500 to 4500 (preferably 2000 to 4000) and a functional group number of 2. The weight ratio of EO units to PO units (EO units:PO units) in polyether polyol B is preferably 1:99 to 40:60, more preferably 4:96 to 20:80, and even more preferably 6:94 to 15:85. The use of polyether polyol B can improve the flexibility of polyurethane foam. Polyether polyol B also serves to refine and homogenize the cells of the polyurethane foam.

[0056] There are no particular limitations on the content of polyether polyol B. The content of polyether polyol B is preferably 10 parts by mass or more and 50 parts by mass or less, and more preferably 15 parts by mass or more and 40 parts by mass or less, based on 100 parts by mass of the entire polyols.

[0057] The polymer polyol more preferably has a weight average molecular weight of 1500 to 4500 (preferably 2000 to 4000) and a functional group number of 2 or 3. As the polymer polyol, for example, a polymer polyol formed by graft copolymerizing a vinyl monomer such as acrylonitrile and styrene onto a polyether polyol having a functional group number of 2 or 3 as a base polyol can be suitably used. Examples of the above-mentioned base polyol include polyether polyols containing PO units and EO units as AO units. The weight average molecular weight of the polymer polyol refers to the weight average molecular weight of the base polyol.

[0058] In addition, the polymer content of polymer polyol (the mass ratio of the part other than the basic polyol relative to the whole polymer polyol) is preferably 10~40 mass %, more preferably 15~30 mass %.From the viewpoint of improving the intensity of polyurethane foam, polymer content is preferably large, but if this polymer content is too large, then there is a possibility that viscosity rises and workability declines. In addition, as polymer polyol, can only contain 1 kind of polymer polyol, can also use together two or more polymer polyols different in weight average molecular weight or polymer content, functional group number etc. By using polymer polyol, the hardness of polyurethane foam can be improved.

[0059] The content of the polymer polyol is not particularly limited. The content of the polymer polyol is preferably 5 parts by mass or more and 60 parts by mass or less, more preferably 25 parts by mass or more and 45 parts by mass or less, based on 100 parts by mass of the entire polyol. If the content of the polymer polyol is 25 parts by mass or more, the air permeability of the polyurethane foam can be appropriately reduced.

[0060] The polyester polyol is more preferably a polyester polyol having a functional group number of 2. The weight average molecular weight of the polyester polyol is preferably in the range of 200 to 2500, more preferably in the range of 250 to 1500, and further preferably in the range of 300 to 800. As the polyester polyol, for example, polycaprolactone polyester polyol, adipic acid polyester polyol, etc. can be used. As the polycaprolactone polyester polyol, for example, polyester polyols obtained by ring-opening addition polymerization of lactones such as ε-caprolactone can be mentioned. As the adipic acid polyester polyol, for example, polyester polyols obtained by condensation polymerization of polyfunctional carboxylic acids and polyfunctional hydroxyl compounds can be mentioned. By using polyester polyols, the strength of polyurethane foam can be improved. In addition, polyester polyols also have the effect of miniaturizing and homogenizing the cells of polyurethane foam.

[0061] The content of the polyester polyol is not particularly limited, but is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the entire polyols.

[0062] In addition, other polyols other than the above-mentioned polyols may be contained as the polyols. As the other polyol, there is no particular limitation as long as it is a polyol generally used in polyurethane foams, and any other polyol can be used.

[0063] In the present disclosure, when low molecular weight polyvalent alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, and sorbitol are used, these polyvalent alcohols are also included in polyols.

[0064] [Isocyanates]

[0065] Isocyanates (polyisocyanates) are compounds having multiple isocyanate groups. Examples of isocyanates include aromatic isocyanates such as 4,4-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, and xylylene diisocyanate (XDI); alicyclic isocyanates such as isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate (HDI); free isocyanate prepolymers obtained by reacting these with polyols; and modified isocyanates such as carbodiimide-modified isocyanates. These isocyanates may be used alone or in combination of two or more.

[0066] The isocyanates may be any of aromatic, alicyclic, and aliphatic isocyanates; they may be bifunctional isocyanates having two isocyanate groups in one molecule; or they may be trifunctional or higher functional isocyanates having three or more isocyanate groups in one molecule; and these may be used alone or in combination.

[0067] For example, bifunctional isocyanates include 2,4-toluene diisocyanate (TDI), 2,6-toluene diisocyanate (TDI), m-p-phenylene diisocyanate, p-p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4'-diphenylmethane diisocyanate (MDI), 2,2'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate, 3,3'-dimethyl-4,4'- Aromatic isocyanates such as biphenyl diisocyanate and 3,3'-dimethoxy-4,4'-biphenyl diisocyanate; alicyclic isocyanates such as cyclohexyl-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate; and aliphatic isocyanates such as 1,4-butyl diisocyanate, hexamethylene diisocyanate, isopropyl diisocyanate, methylene diisocyanate, and lysine isocyanate. Examples of difunctional or higher-functional isocyanates include polymethylene polyphenyl polyisocyanate (polymeric MDI). Examples of trifunctional or higher-functional isocyanates include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'-tetraisocyanate, and triphenylmethane-4,4',4"-triisocyanate. The isocyanates are not limited to being used alone, but may be used alone or in combination. For example, one aliphatic isocyanate and two aromatic isocyanates may be used together.

[0068] The number of functional groups of the isocyanate is preferably in the range of 2.0 to 2.8 from the viewpoint of hardness and resilience.

[0069] In addition, the isocyanate index (INDEX) of isocyanates is preferably in the range of 90 to 110. The isocyanate index is the equivalent ratio of the isocyanate group of the isocyanate relative to the reactive groups such as hydroxyl groups in the polyols that can react with isocyanate. Therefore, when this value is less than 100, it means that the reactive groups such as hydroxyl groups are in excess of the isocyanate groups, and when it exceeds 100, it means that the isocyanate groups are in excess of the reactive groups such as hydroxyl groups. When the isocyanate index is less than 90, it is possible that the polyols cannot fully react with the isocyanates. On the other hand, when the isocyanate index exceeds 110, it is possible to cause the performance of low rebound resilience.

[0070] [Foam stabilizer]

[0071] A foam stabilizer is used to facilitate smooth foaming of the composition, and the composition preferably contains a foam stabilizer. Known foam stabilizers commonly used in mechanical foaming methods can be used as foam stabilizers, for example, silicone foam stabilizers. Due to their high viscosity, such foam stabilizers are typically diluted in a solvent such as alkylbenzene before being added to the composition.

[0072] The foam stabilizer content in the composition is preferably 3 to 6 parts by mass per 100 parts by mass of the polyol. A content of 3 parts by mass or greater improves cell uniformity, contributing to a lower density of the polyurethane foam. However, even if the content exceeds 6 parts by mass, a significant improvement in foam stabilization effectiveness cannot be expected. Furthermore, when diluting the foam stabilizer with a solvent, the preferred mass ratio (foam stabilizer:solvent) is 25:75 to 75:25.

[0073] [catalyst]

[0074] Catalysts are primarily used to promote the polyurethane formation reaction between polyols and isocyanates, and the composition preferably contains a catalyst. Examples of catalysts commonly used in polyurethane foam include tertiary amines such as triethylenediamine, dimethylethanolamine, and N,N',N'-trimethylaminoethylpiperazine; organometallic compounds such as stannous octoate and tin octoate (tin octoate); acetates; and alkali metal alkoxides.

[0075] The catalyst content in the composition is preferably 0.1 to 5.0 parts by mass per 100 parts by mass of the polyol. A content of 0.1 parts by mass or greater can sufficiently promote the polyurethane formation reaction. A content of 5.0 parts by mass or less can prevent uneven cell structure formation due to excessive promotion of the polyurethane formation reaction.

[0076] [Other ingredients]

[0077] The composition may contain other ingredients in addition to the above as needed. Examples of other ingredients include antioxidants, ultraviolet absorbers, thickeners, plasticizers, antibacterial agents, and colorants. Examples of antioxidants include butylated hydroxytoluene and hindered phenolic antioxidants. However, from the perspective of reducing the content of volatile organic compounds, hindered phenolic antioxidants with a molecular weight of 300 or greater are particularly preferred. Examples of thickeners include calcium carbonate, aluminum hydroxide, and magnesium hydroxide.

[0078] 2. Requirements for Conditions (1) and (2)

[0079] The polyurethane foam satisfies any one of the following conditions (1) and (2).

[0080] (1) The content of propylene oxide units in the entire polyol is 75% by mass or more, when the total amount of alkylene oxide units is 100% by mass.

[0081] (2) The content of propylene oxide units in the entire polyether polyol contained in the polyols is 85% by mass or more, when the total amount of alkylene oxide units is 100% by mass.

[0082] Conditions (1) and (2) are indicators indicating that the PO content in the composition is greater than or equal to a predetermined amount. If the PO content in the composition is greater than or equal to the predetermined amount, the air permeability of the polyurethane foam can be appropriately reduced. The polyurethane foam may satisfy only condition (1) or only condition (2). From the perspective of reducing air permeability, the polyurethane foam preferably satisfies both conditions (1) and (2).

[0083] The PO content in condition (1) may be 76% by mass or more, 78% by mass or more, or 80% by mass or more. The PO content in condition (1) may be 100% by mass or less, or 95% by mass or less, 90% by mass or less, or 85% by mass or less. Furthermore, in condition (1), the polyols as a whole may include, in addition to the polyether polyols described in condition (2) below, polyols such as polyester polyols.

[0084] The PO content in condition (2) may be 88% by mass or more, 89% by mass or more, or 90% by mass or more. The PO content in condition (2) may be 100% by mass or less, or 97% by mass or less. Furthermore, in condition (2), the entire polyether polyol may include polyether polyols such as the above-mentioned polyether polyols A and B, a polyether polyol serving as a base polyol for a polymer polyol, and a polyether polyol used as a crosslinking agent.

[0085] 3. Requirements for condition (3)

[0086] The polyurethane foam satisfies the following condition (3).

[0087] (3) A obtained from the above formula (a) and B obtained from the above formula (b) satisfy 2400≦A×B.

[0088] A calculated from formula (a) represents the weight average molecular weight per hydroxyl group in the polyol. When the polyols include a single type of polyol, the weight average molecular weight of the polyol can be calculated by dividing the weight average molecular weight of the polyol by the number of hydroxyl groups per molecule of the polyol. When the polyols include multiple types of polyols, the weight average molecular weight of each polyol can be calculated by multiplying the value obtained by dividing the weight average molecular weight of each polyol by the number of hydroxyl groups per molecule of each polyol by the content (mass %) of each polyol and summing the values.

[0089] For example, in Example 5 (n=9) described below, A is calculated to be 1194 according to the following formula (a-1).

[0090] [Formula 3]

[0091]

[0092] B obtained by formula (b) represents the average number of functional groups of the isocyanates. When the isocyanates contain one type of isocyanate, it can be obtained as the number of its functional groups. When the isocyanates contain multiple types of isocyanates, it can be obtained by multiplying the number of functional groups of each isocyanate by the content (mass %) of each isocyanate and summing them.

[0093] For example, in Example 5 (m=2) described later, B is obtained as 2.4 according to the following formula (b-1).

[0094] [Formula 4]

[0095]

[0096] Multiplying A and B yields the weight-average molecular weight of the polyol per isocyanate molecule. Condition (3) indicates that the weight-average molecular weight of the polyol per isocyanate molecule is at least a specified value. If the weight-average molecular weight of the polyol per isocyanate molecule is at least a specified value, the buffering properties at low temperatures can be adequately maintained. For example, in Example 5, described below, the value of A × B is 2866, calculated from the equation 1194 × 2.4.

[0097] The value of A×B in condition (3) may be 2500 or more, 2600 or more, or 2700 or more. The value of A×B is usually 5000 or less, but may be 4500 or less, 4000 or less, or 3500 or less.

[0098] 4. Physical properties of polyurethane foam

[0099] The physical properties of the polyurethane foam can be appropriately set according to the intended use, etc. The polyurethane foam preferably has the following physical properties.

[0100] The air permeability of the polyurethane foam, when measured using the following measurement method, is preferably 30 seconds or more, more preferably 50 seconds or more, and even more preferably 60 seconds or more. The upper limit of the air permeability of the polyurethane foam is not particularly limited. If the air permeability exceeds 600 seconds, the measurement may be stopped to set the air permeability to exceed 600 seconds.

[0101] [Measurement method]

[0102] A polyurethane foam sheet with a thickness of 3 mm was obtained. The sample with double-sided tape 13 attached to one side was punched into a ring shape with an inner diameter of 24 mm and an outer diameter of 30 mm to obtain a sample. Figure 3 As shown, the sample was compressed in the thickness direction to a compression ratio of 60%. Nitrogen gas was flowed into the cavity CB connected to the inner circumference of the sample until the pressure reached 19 kPa. The time it took for the pressure in the cavity CB to decrease to 18 kPa was then measured. This measured time was defined as the air permeability (seconds) of the polyurethane foam.

[0103] The glass transition point of the polyurethane foam is preferably -20°C or lower, preferably -25°C or lower, and more preferably -35°C or lower. The lower limit of the glass transition point of the polyurethane foam is not particularly limited, but is usually -100°C or higher.

[0104] In the present disclosure, the glass transition point is defined as the peak temperature of tan δ obtained when viscoelasticity is measured under the conditions of a frequency of 1 Hz and a temperature increase rate of 3° C. / min.

[0105] The coefficient of hystereisis loss of the polyurethane foam is preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less, when measured by the following measurement method. The lower limit of the hystereisis loss is not particularly limited, but is usually 5% or more.

[0106] [Measurement method]

[0107] A circular sample 3 mm thick and 50 mm in diameter was obtained from polyurethane foam. The compressive stress was measured when the sample was compressed 50% at a rate of 1 mm / min and when it was compressed from 50% to 0%. The hysteresis loss rate (%) was calculated based on the force-deflection curve obtained from the measurements.

[0108] The apparent density (JIS K7222) of the polyurethane foam is preferably 100 kg / m 3 ~500kg / m 3 , more preferably 200kg / m 3 ~400kg / m 3 , more preferably 220kg / m 3 ~350kg / m 3 When the apparent density is equal to or greater than the lower limit, when the toner seal member 10 described later is used, leakage of toner from the cross section can be appropriately suppressed.

[0109] The average cell diameter of the polyurethane foam is preferably 50 to 300 μm, more preferably 50 to 200 μm, and even more preferably 50 to 100 μm. When the cell diameter is equal to or less than the upper limit, the toner seal member can have sufficient sealing properties.

[0110] The average cell diameter of the polyurethane foam can be calculated by dividing the cumulative cell diameters of cells contacting a 25 mm straight line by the number of cells when observing a cross section of the polyurethane foam at 200x magnification using a scanning electron microscope.

[0111] 5. Method for manufacturing polyurethane foam

[0112] Polyurethane foam can be produced using a common polyurethane foam production method used when mechanical foaming is employed. For example, the composition is placed into a mixing head and stirred while incorporating an inert gas to achieve uniform mixing. The composition mixed in the mixing head is then heat-cured on release paper or in a predetermined mold to produce polyurethane foam.

[0113] 6. Toner seal member 10

[0114] like Figure 1 As shown, a container 20 for storing toner includes a discharge portion 22 and a cylindrical toner container 21. The discharge portion 22 has a discharge port 22A for discharging toner, and the toner container 21 is rotatable relative to the discharge portion 22. The toner seal member 10 is annular and seals the joint between the discharge portion 22 and the toner container 21.

[0115] The toner seal member 10 has the above-mentioned polyurethane foam. For example, Figure 2 As shown, the toner seal member 10 includes a foam layer 11 made of polyurethane foam and a coating layer 12 provided on one surface of the foam layer 11. The coating layer 12 can be formed using a coating agent such as acrylic resin, polyurethane resin, or silicone resin.

[0116] The thickness of the foam layer is not particularly limited. From the viewpoint of sealing performance, the thickness of the foam layer is preferably 0.5 mm to 6 mm, more preferably 1 mm to 3 mm, and even more preferably 1 mm to 2 mm.

[0117] The thickness of the coating layer 12 is not particularly limited. From the viewpoint of ensuring sliding properties, the thickness of the coating layer 12 is preferably 0.5 μm to 30 μm.

[0118] The surface of the toner seal member 10 facing the foam layer 11 is fixed to the discharge portion 22 via an adhesive layer (not shown). The surface of the toner seal member 10 facing the coating layer 12 is in contact with the toner container 21, allowing the toner container 21 to slide. The toner seal member 10 is compressed in the thickness direction between the discharge portion 22 and the toner container 21. From the perspective of sealing performance and flexibility, the compression rate of the toner seal member 10 is preferably 10% to 80%, and more preferably 30% to 50%.

[0119] In addition to the above-described toner seal member 10 , the above-described polyurethane foam may be used for the toner seal member 110 that slidably opens and closes the discharge port 22A.

[0120] Furthermore, the polyurethane foam can also be used in components other than toner seals, such as vibration and shock absorbing materials and dustproof sealing materials in electronic equipment such as mobile phones, cameras, and televisions.

[0121] 7. Method for Manufacturing Toner Seal Member 10

[0122] The toner seal member 10 can be obtained by applying a coating agent to one side of the polyurethane foam produced by the above-described method and curing the coating agent to obtain a sheet-like laminate, and then punching the laminate into a ring shape in the thickness direction. The toner seal member 10 thus obtained exhibits a cross-section obtained by cutting the laminate at its inner and outer peripheral surfaces.

[0123] 8. Functions and Effects of This Implementation

[0124] In recent years, various properties have been required of polyurethane foam, and these requirements have become increasingly stringent. For example, the toner sealing member 10 that seals the seam of the container 20 that holds the toner is required to be able to seal the toner on the inner circumference and the sliding surface. The inner circumference of the toner sealing member 10 is the cross-section of the polyurethane foam when it is cut. Compared with the surface of the polyurethane foam, the cross-section of the polyurethane foam is more likely to have open cells, and compared with a structure that seals the toner in the thickness direction, it is more likely to cause toner leakage. Therefore, in order to suppress toner leakage, the polyurethane foam is required to have low air permeability. Furthermore, it is also required that the toner sealing member 10 does not generate a gap between itself and the toner holding portion 21 with respect to vibration during transportation, and maintains cushioning (followability) under a wide range of temperature environments, especially at low temperatures.

[0125] The polyurethane foam of this embodiment is less likely to lose its cushioning properties even at low temperatures. Unlike this embodiment, conventional toner seals using polyurethane foam have a high glass transition point, which can sometimes cause toner leakage during low-temperature drop tests. On the other hand, the toner seal 10 using the polyurethane foam of this embodiment has a low glass transition point and can maintain its cushioning properties even in low-temperature environments. Therefore, the toner seal 10 follows the toner container 21, suppressing toner leakage during low-temperature drop tests.

[0126] The polyurethane foam of this embodiment has low air permeability. Unlike this embodiment, conventional toner seal members using polyurethane foam have a highly air-permeable cell structure, which can easily cause toner leakage. On the other hand, the toner seal member 10 using the polyurethane foam of this embodiment achieves low air permeability by changing the composition of the polyol, making toner leakage less likely to occur.

[0127] The polyurethane foam of this embodiment achieves high rebound resilience by adjusting the composition. Therefore, the toner seal member 10 using the polyurethane foam of this embodiment is less likely to have a gap with the toner container 21, and toner leakage from the toner container 21 is less likely to occur.

[0128] In addition, polyurethane foam is not limited to the toner sealing member 10 and can be used for various purposes. For example, polyurethane foam is suitable as a cushioning material because it achieves high resilience. Polyurethane foam is suitable as a cushioning material used in vehicle-mounted components because its cushioning properties are difficult to be damaged even at low temperatures, such as a cushioning material configured between cells of a vehicle-mounted battery. In addition, polyurethane foam has little change in properties such as hardness over a wide temperature range from low to high temperatures, is dustproof, and achieves high responsiveness, so it is also suitable as a sealing cushioning material used in electronic equipment or sensor parts. In addition, the so-called high responsiveness can be achieved, for example, by reducing the hysteresis loss rate.

[0129] Example

[0130] Next, the above-mentioned embodiment will be described in more detail with reference to Examples and Comparative Examples.

[0131] 1. Production of polyurethane foam

[0132] First, the raw material components of the composition used for the polyurethane foam of each Example and each Comparative Example are shown below.

[0133] Polymer polyol 1: a polymer polyol having a weight average molecular weight of 3000, a functional group number of 3, a hydroxyl value of 42 mgKOH / g, a polymer content of 22.9% by mass, an EO content of 0%, and a PO content of 100%.

[0134] Polymer polyol 2: a polymer polyol having a weight average molecular weight of 3000, a functional group number of 2, a hydroxyl value of 28.6 mgKOH / g, a polymer content of 20.0% by mass, an EO content of 10%, and a PO content of 90%.

[0135] Polyether polyol 1: a polyether polyol having a weight average molecular weight of 3000, a functional group number of 2, a hydroxyl value of 37.4 mgKOH / g, an EO content of 10%, and a PO content of 90%.

[0136] Polyether polyol 2: a polyether polyol having a weight average molecular weight of 3000, a functional group number of 3, a hydroxyl value of 56.1 mgKOH / g, an EO content of 0%, and a PO content of 100%.

[0137] Polyether polyol 3: a polyether polyol having a weight average molecular weight of 3400, a functional group number of 3, a hydroxyl value of 50.3 mgKOH / g, an EO content of 80%, and a PO content of 20%.

[0138] Polyether polyol 4: a polyether polyol having a weight average molecular weight of 2000, a functional group number of 2, a hydroxyl value of 56.1 mgKOH / g, an EO content of 0%, and a PO content of 100%.

[0139] Polyether polyol 5: a polyether polyol having a weight average molecular weight of 3000, a functional group number of 3, a hydroxyl value of 56.1 mgKOH / g, an EO content of 0%, and a PO content of 100%.

[0140] Polyester polyol: Polycaprolactone diol with a weight average molecular weight of 529, a functional group number of 2, and a hydroxyl value of 212 mgKOH / g. The EO content and PO content were 0%.

[0141] Other polyols: dipropylene glycol with a molecular weight of 134, a functional group of 2, and a hydroxyl value of 837 mgKOH / g. The EO content and PO content were 0%.

[0142] Aluminum hydroxide (manufactured by Sumitomo Chemical Co., Ltd., CW-325LV)

[0143] Foam stabilizer: Silicone foam stabilizer (manufactured by Dow Corning Toray, SZ-1952)

[0144] Catalyst 1: Iron catalyst (manufactured by Nippon Chemical Industry Co., Ltd., FIN-P1)

[0145] Catalyst 2: Nickel catalyst (manufactured by Momentive Performance Materials Japan, LC-5615)

[0146] Antioxidant: Hindered phenol antioxidant (manufactured by BASF Japan, IRGANOX 1135)

[0147] Moisture absorbent: Zeolite (Molecular Sieve 3APOWDER manufactured by UNION SHOWA Co., Ltd.)

[0148] Isocyanate 1: Polymeric MDI with a molecular weight of 320, a functional group of 2.4, and an NCO% of 31.5%

[0149] Isocyanate 2: Carbodiimide-modified MDI with a molecular weight of 292, a functional group of 2, and an NCO% of 30.88%

[0150] In addition, the numerical values ​​of each component in Table 1 and Table 2 represent parts by mass. The "F" column in Table 1 and Table 2 shows the number of hydroxyl groups in the polyols and the number of isocyanate groups in the isocyanates. The "Mw" column in Table 1 and Table 2 shows the weight average molecular weight. "Polyether polyol 2" and "Polyether polyol 5" in Table 1 and Table 2 correspond to "Polyether polyol A" described in the embodiment. "Polyether polyol 1" in Table 1 and Table 2 corresponds to "Polyether polyol B" described in the embodiment.

[0151] The above components were prepared in the proportions shown in Tables 1 and 2 below to produce the compositions of each Example and Comparative Example. The compositions were then placed in a mixing head and stirred to achieve uniform mixing while incorporating an inert gas (nitrogen) at a concentration of 69 to 77% by volume. The mixed composition was then applied to a continuously supplied film of a specified thickness and cured by heating at 120 to 200°C to produce a sheet of polyurethane foam.

[0152] [Table 1]

[0153]

[0154] [Table 2]

[0155]

[0156] 2. Observation of polyurethane foam

[0157] The cross-sections of the sheets of each example and each comparative example were observed using a SEM (Scanning electron microscope). Figure 4-6 Shown in.

[0158] The average cell diameter of the polyurethane foam of the examples was 50 μm or more and 300 μm or less. In addition, the polyurethane foam of Example 5 was found to have fewer and smaller openings connecting adjacent cells than the polyurethane foams of Comparative Examples 1 and 2.

[0159] 3. Evaluation

[0160] Next, the following evaluations were performed on the obtained polyurethane foams of the respective Examples and Comparative Examples.

[0161] [PO content in all polyols]

[0162] The content of propylene oxide units in the entire polyols was calculated when the total amount of alkylene oxide units was 100% by mass. The results are shown in the column "PO content in all polyols" in Table 3.

[0163] [PO content in polyether polyol]

[0164] The content of propylene oxide units in the entire polyether polyol included in the polyols was calculated when the total amount of alkylene oxide units was set to 100% by mass. The results are shown in the column "PO content in polyether polyol" in Table 3.

[0165] [Breathability]

[0166] The air permeability (seconds) was measured by the method described in the embodiment. The measurement results are shown in the "Air Permeability" column of Table 3, and were evaluated based on the following criteria.

[0167] “◯”: Air permeability is 50 seconds or more.

[0168] “△”: Air permeability is more than 30 seconds and less than 50 seconds.

[0169] “×”: Air permeability is less than 30 seconds.

[0170] [Weight average molecular weight per hydroxyl group in polyol: A]

[0171] In this example, nine polyols were used, and "n=9" in formula (a). A was calculated based on the above formula (a). The results are shown in the "Average molecular weight per hydroxyl group in polyol: A" column in Table 3.

[0172] [Weight average molecular weight of polyol per isocyanate molecule: A×B]

[0173] In this example, two isocyanates were used, and in formula (b), "m = 2." B was calculated based on formula (b). In Comparative Example 1, B was 2. In Comparative Examples 2 and 3, and in the examples, B was 2.4. A and B were multiplied to calculate the value of A × B. The results are shown in the "Average molecular weight per isocyanate molecule" column in Table 3.

[0174] [Glass transition point]

[0175] The glass transition point (° C.) was measured by the method described in the embodiment. The measurement results are shown in the column “Glass transition point” in Table 3, and were evaluated based on the following criteria.

[0176] "○": Glass transition point is -20°C or lower.

[0177] “×”: The glass transition point is higher than -20°C.

[0178] [Hysteresis loss rate]

[0179] The hysteresis loss rate (%) was measured by the method described in the embodiment. The measurement results are shown in the "Hysteresis Loss Rate" column of Table 3, and were evaluated based on the following criteria.

[0180] “○”: The hysteresis loss rate is 15% or less.

[0181] “×”: The hysteresis loss rate is less than 15%.

[0182] [density]

[0183] Apparent density (kg / m 3 The measurement results are shown in the "Density" column of Table 3.

[0184] [Comprehensive evaluation]

[0185] “A”: The evaluation of air permeability was 0, the evaluation of glass transition point was 0, and the evaluation of hysteresis loss rate was 0.

[0186] “B”: The evaluation of air permeability was △, the evaluation of glass transition point was 0, and the evaluation of hysteresis loss rate was 0.

[0187] “C”: Any one of the evaluation of air permeability, the evaluation of glass transition point, and the evaluation of hysteresis loss rate was rated as ×.

[0188] [Table 3]

[0189]

[0190] 4. Results

[0191] When the "PO content in all polyols" in Table 3 is 75% or more, the above-mentioned condition (1) is satisfied. When the "PO content in polyether polyol" in Table 3 is 85% or more, the above-mentioned condition (2) is satisfied. When the "average molecular weight per isocyanate molecule" in Table 3 is 2400 or more, the above-mentioned condition (3) is satisfied.

[0192] Examples 1 to 10 satisfy the following requirements (a) and (b).

[0193] Requirement (a): Satisfy either of the above conditions (1) and (2).

[0194] Requirement (b): Satisfy the above-mentioned condition (3).

[0195] In contrast, Comparative Examples 1 to 3 did not satisfy the following requirements.

[0196] Comparative Example 1 does not satisfy the requirement (b).

[0197] Comparative Examples 2 and 3 do not satisfy requirement (a).

[0198] Examples 1 to 10 were evaluated as having high comprehensive ratings compared to Comparative Examples 1 to 3. Examples 1 to 10 had high rebound resilience, were less likely to lose cushioning properties even at low temperatures, and had low air permeability.

[0199] In addition, among Examples 1 to 10, Examples 3 to 10 that further satisfied the following requirement (c) had lower air permeability.

[0200] Requirement (c): As the polyol, the polyol contains 25 parts by mass or more and 45 parts by mass or less of a polymer polyol having a weight average molecular weight of 1500 to 4500, based on 100 parts by mass of the entire polyol.

[0201] In addition, the following inventions can be understood from the above-mentioned embodiments and comparative examples. For the description of specific matters of the following inventions, the above-mentioned respective descriptions are appropriately cited.

[0202] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the polyurethane foam satisfies the following condition (1-1).

[0203] (1-1) When the total amount of alkylene oxide units in the entire polyol is 100% by mass, the content of propylene oxide units is 76% by mass or more.

[0204] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the polyurethane foam satisfies the following condition (2-1).

[0205] (2-1) The content of propylene oxide units is 89% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass.

[0206] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the polyurethane foam satisfies the following condition (3-1).

[0207] (3-1) For A obtained from the above formula (a) and B obtained from the above formula (b),

[0208] Satisfies 2600≦A×B.

[0209] The performance required of polyurethane foam varies depending on its application, etc., and the following invention can also be understood based on the above-mentioned Examples and Comparative Examples. For the description of the specific matters of the following invention, the above-mentioned descriptions are appropriately cited.

[0210] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the polyurethane foam has an air permeability of 40 seconds or more as determined by the above-mentioned measurement method.

[0211] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the polyurethane foam has a glass transition point of -20°C or lower as determined by the above-mentioned measurement method.

[0212] A polyurethane foam obtained from a composition containing polyols and isocyanates, wherein the hysteresis loss rate determined by the above-mentioned measurement method is 15% or less.

[0213] 5. Effects of the Embodiments

[0214] According to the above embodiments, it is possible to provide a polyurethane foam having high rebound resilience, which is less likely to lose its cushioning properties at low temperatures, and which has low air permeability.

[0215] The present disclosure is not limited to the embodiments described in detail above, and various modifications and changes can be made within the scope of the claims of the present disclosure.

[0216] Description of Reference Numerals

[0217] 10: Toner seal member,

[0218] 11: Foam layer,

[0219] 12: coating layer,

[0220] 13: Double-sided tape,

[0221] 20: container,

[0222] 21: Toner storage portion,

[0223] 22: discharge part,

[0224] 22A: outlet,

[0225] 110: Toner sealing member.

Claims

1. A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, The apparent density of the polyurethane foam is 100 kg / m 3 ~500kg / m 3 , (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, where m is a natural number of 1 or greater, and the amount is expressed in parts by mass.

2. A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, The polyols contain 1 part by mass or more and 20 parts by mass or less of polyester polyol based on 100 parts by mass of the entire polyols. (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, where m is a natural number of 1 or greater, and the amount is expressed in parts by mass.

3. The polyurethane foam according to claim 2, wherein As the polyols, polyether polyols are included; The polyether polyol comprises a polyether polyol A containing only propylene oxide units as alkylene oxide units and a polyether polyol B containing propylene oxide units and ethylene oxide units as alkylene oxide units. The polyether polyol A is a polyether polyol with a weight average molecular weight of 1500 to 4500 and a functional group number of 3. The polyether polyol B is a polyether polyol with a weight average molecular weight of 1500 to 4500 and a functional group number of 2. The weight ratio of ethylene oxide units to propylene oxide units in the polyether polyol B, i.e., ethylene oxide units:propylene oxide units, is 1:99 to 40:

60.

4. The polyurethane foam according to any one of claims 1 to 3, wherein The functional group number of the isocyanate is 2.0 or more and 2.8 or less.

5. The polyurethane foam according to any one of claims 1 to 3, wherein For A obtained from the above formula (a) and B obtained from the above formula (b), Satisfy 2700≦A×B.

6. A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, The air permeability measured by the following method is 40 seconds or more. (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, m is a natural number greater than 1, and the amount is expressed in parts by mass, The measurement method is: A polyurethane foam sheet with a thickness of 3 mm was obtained; a sample with double-sided tape attached to one side was punched into a ring shape with an inner diameter of 24 mm and an outer diameter of 30 mm to obtain a sample; the sample was compressed in the thickness direction to a compression ratio of 60%; nitrogen gas was flowed into a cavity connected to the space on the inner circumference of the sample until the pressure rose to 19 kPa; then, the time it took for the pressure in the cavity to decrease to 18 kPa was measured; the measured time was defined as the air permeability of the polyurethane foam, and the air permeability was expressed in seconds.

7. A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, The glass transition point, obtained as the temperature of the peak of tan δ obtained when viscoelasticity is measured at a frequency of 1 Hz and a temperature increase rate of 3°C / min, is -20°C or lower. (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, where m is a natural number of 1 or greater, and the amount is expressed in parts by mass.

8. A polyurethane foam obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, The hysteresis loss rate determined by the following measurement method is less than 15%. (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, where m is a natural number greater than 1 and the amount is expressed in parts by mass; The measurement method is: A circular sample with a thickness of 3 mm and a diameter of 50 mm was obtained from polyurethane foam; the compressive stress when the sample was compressed 50% at a speed of 1 mm / min and the compressive stress when the sample was compressed from 50% to 0% were measured; and the hysteresis loss rate was calculated based on the force-deflection curve obtained by the measurement, and the hysteresis loss rate was expressed as %.

9. The polyurethane foam according to any one of claims 1, 2, 6 to 8, wherein As the polyols, The polyols may contain 5 parts by mass or more and 60 parts by mass or less of a polymer polyol having a weight average molecular weight of 1500 to 4500, based on 100 parts by mass of the entire polyols. Alternatively, When the total amount of the polyols is 100 parts by mass, the polyether polyol having a weight average molecular weight of 1500 to 4500 is contained in an amount of 10 parts by mass or more and 50 parts by mass or less, or When the entire polyol is 100 parts by mass, the polyester polyol having a weight average molecular weight of 300 to 800 is contained in an amount of 1 part by mass or more and 20 parts by mass or less.

10. A toner seal member, wherein: A polyurethane foam according to any one of claims 1 to 9.

11. A cushioning material disposed between cells of a vehicle-mounted battery, comprising polyurethane foam, wherein: The polyurethane foam is obtained from a composition comprising polyols and isocyanates, wherein: The following conditions (1) and (2) are met, and the following condition (3) is met, (1) The content of propylene oxide units is 75% by mass or more, when the total amount of alkylene oxide units in the entire polyol is 100% by mass; (2) the content of propylene oxide units is 85% by mass or more, when the total amount of alkylene oxide units in the entire polyether polyol contained in the polyol is 100% by mass; (3) For A obtained from the following formula (a) and B obtained from the following formula (b), Satisfy 2400≦A×B; m1i: the weight average molecular weight of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1, and i is a natural number such that 1≦i≦n; f1i: the number of hydroxyl groups per molecule of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n; x1i: the amount of the i-th polyol among the n polyols included in the polyols, where n is a natural number greater than 1 and i is a natural number such that 1≦i≦n, and the amount is expressed in parts by mass; y1: the total amount of n types of polyols contained in the polyols, where n is a natural number greater than 1 and the amount is expressed in parts by mass; f2i: the number of isocyanate groups per molecule of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m; x2i: the amount of the i-th isocyanate among the m isocyanates contained in the isocyanates, where m is a natural number greater than 1 and i is a natural number such that 1≦i≦m, and the amount is expressed in parts by mass; y2: the total amount of m types of isocyanates contained in the isocyanates, where m is a natural number of 1 or greater, and the amount is expressed in parts by mass.

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