JP2003048944A - Flexible polyurethane foam and toner-sealing material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible polyurethane foam having an adequate hardness and excellent aging resistance in wet heat, and further to provide a toner-sealing material obtained by using the polyurethane foam, and having sufficient sealing properties. SOLUTION: This flexible polyurethane foam is obtained by reacting a raw material for the foam comprising a polyisocyanate and a polyol. The polyol comprises a polyether polyol in which the number of the functional groups is 2, and which has 500-1,800 number average molecular weight, and a polyester polyol in which the number of the functional groups is 3, and which has 1,500-4,000 number average molecular weight. Preferably, a low molecular weight triol in which the number of the functional groups is 3 and which has 250-1,400 number average molecular weight is included as the polyol component. The toner-sealing material comprises the specific flexible polyurethane foam.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flexible polyurethane foam obtained by reacting a foam raw material containing a polyisocyanate and a specific polyol, and a toner sealing material using the same. The flexible polyurethane foam of the present invention has an appropriate hardness and a small wet heat strain. Therefore, it is useful as a toner seal material used in a process cartridge mounted in an electrophotographic image forming apparatus such as various printers, facsimiles, and copying machines.

[0002]

2. Description of the Related Art In image forming apparatuses such as various printers, a latent image is formed by selectively exposing a uniformly charged image carrier to form a latent image, and the latent image is visualized with toner. The image is recorded by transferring the toner image to the recording medium. In such an apparatus, it is necessary to replenish the toner in a timely manner, but this replenishment work is not only complicated, but may be accompanied by stains on fingers or the surroundings. Further, maintenance of the toner container and the like requires specialized technology, which is inconvenient for the user.

Therefore, there is provided a product in which an image carrier, a charging device, a developing device, a cleaning device and the like are integrated into a cartridge. With this product, the user can replenish the toner or replace the image carrier that has reached the end of life by detaching the cartridge from the apparatus main body, which facilitates maintenance. This process cartridge system is adopted in many image forming apparatuses, but if toner leaks out, an image defect occurs. Therefore, a toner seal material is provided on the contact surface of the resin molded product, such as between the frame bodies of the cartridge body and the gap between the developing sleeve and the developing frame body of the developing device. Further, a sealing material is provided in the gap between the end of the image carrier of the cleaning device and the waste toner retainer so that the waste toner does not leak out at the end of the image carrier.

As the sealing material, various foams such as polyurethane foam, and various elastic bodies such as soft rubber or elastomer are used. Also,
In the case of foam, generally, a material with low air permeability, a large number of cells (small cell diameter), and high sealing property is used, and in order to further improve the sealing property, a hot pressed foam may be used. Many. As such a flexible sealing material, for example, Japanese Patent Application Laid-Open Nos. 9-109290 and 7-92887 disclose a sealing material made of a liquid elastomer. It is possible to seal by interposing these sealing materials on the respective contact surfaces, compressing the sealing materials appropriately and deforming them.

[0005]

However, in the hot-pressed foam, the sealing material is too hard, the repulsive force becomes excessively large, and the resin molded product such as the frame of the cartridge body is deformed or cracked. I have something to do. Further, with the recent improvement in printing technology, the toner has been made finer (about 8 μm) in order to produce a more beautiful image, and the current sealing material cannot sufficiently prevent the leakage of the toner. There are also problems. For example, conventional toners containing carbon black as a main component could be sufficiently sealed with conventional sealing materials, but fine toners used for color prints have a sealing material made of a specific polyurethane foam or the like. Otherwise it may not be possible to seal.

It is possible to use an existing water-stop foam for such an application, but this foam generally has a problem of large wet heat distortion. The process cartridge or a product incorporating the process cartridge is often transported by ship, but may be exposed to a harsh atmosphere such as high temperature and high humidity during transportation. At that time, the sealing material interposed between the frames of the cartridge body in a compressed state must maintain the repulsive force against the compression for a long period of time. That is,
The compression set must be small. The present invention is to solve the above-mentioned conventional problems, to provide a soft polyurethane foam having appropriate hardness and small wet heat strain, and a toner sealing material using the foam and having a sufficient sealing property. The purpose is to provide.

[0007]

[Means for Solving the Problems] As a polyol, a polyether polyol having a specific number of functional groups and a number average molecular weight and a polyester polyol are used in combination, so that the polyol has appropriate hardness, low air permeability and wet heat strain. Can be a sufficiently small flexible polyurethane foam. Further, by using this foam, a toner sealing material having excellent sealing properties can be obtained. The present invention has been made based on such findings.

The flexible polyurethane foam of the present invention is a polyurethane foam obtained by reacting a foam raw material containing a polyisocyanate and a polyol component. The polyol component has a functional group number of 2 and a number average molecular weight of 500 to 1800. A polyether polyol and the number of functional groups is 3, and the number average molecular weight is 1500.
It is characterized by containing a polyester polyol having a molecular weight of up to 4000.

As the above-mentioned "polyisocyanate", those generally used in the production of flexible polyurethane foam can be used. For example, diphenylmethane diisocyanate (hereinafter referred to as “MDI”), toluene diisocyanate (hereinafter referred to as “TDI”), and MDI / TDI mixture, or modified products such as MDI and TDI can be used.

MDI is particularly preferred as the polyisocyanate. If MDI is used, the cell diameter becomes smaller and the sealing property is improved. This MDI is usually
Crude MDI [In the synthetic process, diphenylmethanediamine phosgenate was converted into pure MDI (diphenylmethane 4,
4'-diisocyanate) is the remainder removed by rectification and is a mixture of a binuclear body and a polynuclear body. ] Is used, but may be pure MDI. From an economic point of view, crude MDI is preferable. The TDI is usually 2,
A mixture of 4-TDI and 2,6-TDI is used.
Further, it is also possible to use pure TDI having a high purity of one of these or crude TDI obtained by removing pure TDI by rectification after synthesis.

The polyisocyanate content is preferably 40 to 70 parts by mass, particularly 45 to 65 parts by mass, and more preferably 50 to 60 parts by mass, based on 100 parts by mass of the total amount of polyols. If the content of the polyisocyanate is less than 40 parts by mass, the wet heat strain may increase. On the other hand, if it exceeds 70 parts by mass, it may become too hard.

Examples of the above-mentioned "polyol" include the above-mentioned "polyether polyol" having 2 functional groups and a number average molecular weight of 500 to 1800, and 3 functional groups.
The “polyester polyol” having a number average molecular weight of 1500 to 4000 is used in combination. By using these polyols, the wet heat strain of the foam can be made sufficiently small.

When the number of functional groups of the polyether polyol is not 2, the wet heat strain cannot be sufficiently reduced. The number average molecular weight is 500 to 1500, and particularly 500 to 120.
It is preferably 0, more preferably 500 to 1000. When the number average molecular weight is less than 500 or exceeds 1800, the wet heat strain does not become sufficiently small.

The content of this polyether polyol is
40 to 8 when the total amount of the polyether polyol and the polyester polyol is 100 parts by mass.
It is preferably 5 parts by mass, particularly 50 to 80 parts by mass, and further preferably 60 to 75 parts by mass. If the content of the polyether polyol is less than 40 parts by mass, the foam may be too hard and the frame body may be deformed. Further, the air permeability tends to be high and the sealing property tends to be low. On the other hand, when it exceeds 85 parts by mass, the cell diameter becomes large and the sealing property may be deteriorated.

When the number of functional groups of the polyester polyol is not 3, the wet heat strain cannot be sufficiently reduced. The number average molecular weight is 1800 to 4000, especially 2000 to 35.
00, and more preferably 2500 to 3000. If the number average molecular weight is less than 1,500, the foam may be too hard and may deform a member such as a frame, or the air permeability may be increased to deteriorate the sealing property. On the other hand, 40
If it exceeds 00, the wet heat strain does not become sufficiently small.

The content of this polyester polyol is
When the total amount of the polyether polyol and the polyester polyol is 100 parts by mass, 15 to 6
It is preferably 0 parts by mass, particularly 20 to 50 parts by mass, and further preferably 25 to 40 parts by mass. When the content of the polyester polyol is less than 15 parts by mass, the cell diameter may be large and the sealing property may be deteriorated. On the other hand, if the amount exceeds 60 parts by mass, the foam may become too hard, which may deform members such as a frame or may increase the air permeability and deteriorate the sealing property.

As the polyol, in addition to the above-mentioned specific polyether polyols and polyester polyols, polyether polyols and polyester polyols having a number of functional groups of 3 and a number average molecular weight of 250 to 1400 (hereinafter referred to as "low molecular weight triols"). It is more preferable to use at least one of the above). By using this low-molecular-weight triol in combination, the hardness can be reduced and a foam having an appropriate repulsive force can be obtained. When the number of functional groups of the polyol used in combination is not 3,
Wet heat strain tends to increase. If the number average molecular weight is less than 250, the hardness of the foam may not be sufficiently reduced. On the other hand, when it exceeds 1400, the wet heat strain tends to increase.

The number average molecular weight of the low molecular weight triol is 2
It is preferably from 50 to 1000, particularly from 250 to 700. By using such a low molecular weight triol in combination, a foam having a smaller wet heat strain can be obtained. Further, as the low molecular weight triol, a polyether polyol is particularly preferable, and a polyether polyol can form a foam having a small wet heat strain and a low hardness.

The content of the low molecular weight triol is not particularly limited, but can be 10 to 70 parts by mass and 20 to 50 parts by mass when the total amount of the polyol is 100 parts by mass.
It is preferable that the amount is, for example, 35 to 40 parts by mass.
If the content of the low molecular weight triol is less than 10 parts by mass, the hardness of the foam may not be sufficiently reduced. On the other hand, if it exceeds 70 parts by mass, the wet heat strain tends to increase.

As the polyol, a polycarbonate-based polyol, a polydiene-based polyol, etc. are contained in addition to the above-mentioned specific polyol as long as the proper hardness of the toner sealing material and the excellent resistance to moisture and heat aging are not impaired. May be. Only one kind of these other polyols may be contained, or two or more kinds thereof may be contained.

The "foam raw material" contains a catalyst. As this catalyst, an amine catalyst that does not have a group that reacts with polyisocyanate such as an amino group, a hydroxyl group, and a carboxyl group is preferable. By using this specific amine catalyst, a foam having a smaller wet heat strain can be obtained. Examples of such amine catalysts include N-methylmorpholine and triethylenediamine. The content of the amine catalyst can be 0.3 to 3 parts by mass, and 0.5 to 2.5 parts by mass, particularly 0.7 to 100 parts by mass, when the total amount of the polyol is 100 parts by mass.
It is preferably 1.5 parts by mass.

The foam raw material is polyisocyanate,
In addition to the polyol and the catalyst, a foam stabilizer such as a silicon foam stabilizer and a foaming agent such as water are contained. Further, other auxiliary agents and the like can be contained as necessary. Examples of the auxiliaries include flame retardants, antioxidants, ultraviolet absorbers, coloring agents, and various diluents for lowering the viscosity of foam raw materials and facilitating stirring and mixing. These can be contained in appropriate amounts within a range that does not impair the hardness, wet heat strain, etc. of the foam. The catalyst, foam stabilizer, foaming agent, etc.
Usually, it is blended with a polyol and mixed with a polyisocyanate during the reaction.

The method for producing the flexible polyurethane foam of the present invention is not particularly limited, and a general method for producing this type of foam can be employed as it is. In addition, this foam does not chemically attack the resin member such as the frame of the cartridge (so-called chemical attack), has a suitable hardness even when exposed to a harsh atmosphere, and has an excellent resistance to moisture and heat. The aging property is hardly deteriorated and the excellent sealing property is maintained for a long time. Therefore, it can be used as various sealing materials that do not allow dust, dust, powder, gas, etc. to permeate, or prevent them from entering the inside. Examples of such a sealing material include a toner sealing material and an air sealing material for a door for an air conditioner provided in various air ducts of a vehicle or the like.

The toner sealing material of the present invention is characterized by comprising the above-mentioned flexible polyurethane foam. With the toner sealing material made of such a foam, even if it is exposed to a harsh atmosphere, the hardness and the repulsion force are maintained for a long period of time, and the excellent resistance to heat and heat aging is maintained, and the frame body or the like is deformed. And leakage of toner is sufficiently prevented.
Further, even if the compression rate is low, the sealing property is good, and the toner can be sufficiently prevented from leaking out only by interposing it on the contact surface such as the frame of the cartridge and appropriately compressing it. Therefore, the structure of the member such as the frame of the toner cartridge can be simplified, and the required amount of resin can be reduced. Therefore, it is also advantageous in terms of cost reduction.

The foam used as the toner sealing material has a cell number of 50 cells / 25 mm or more and JIS L1.
The air permeability measured according to the 096 B method is preferably 3 seconds or more. With such a foam, it is possible to obtain a toner sealing material having excellent sealing properties. Also,
The number of cells is 60 cells / 25mm or more, especially 65 cells / 25m
m or more and air permeability of 5 seconds or more, particularly 50 seconds or more,
Furthermore, if it is 80 seconds or more, a toner sealing material having more excellent sealing property can be obtained.

Further, the foam used as the toner sealing material has a CLD hardness of 10 kPa or less, is 50% compressed, and has a wet heat strain of 9% after being exposed to an atmosphere of 70 ° C. and 95% relative humidity for 24 hours. The following is preferable. With such a foam, the frame and the like of the cartrisch are not deformed by excessive repulsive force, and sufficient sealing property is maintained even after being exposed to a harsh atmosphere. Further, if the CLD hardness is 7.5 kPa or less, particularly 6.5 kPa or less, further 5.0 kPa or less, and the wet heat strain is 7% or less, particularly 5% or less, further 4% or less, It has excellent durability and sufficient sealability is maintained for a longer period of time.

In the present invention, a toner sealing material having the above preferable number of cells, air permeability, CLD hardness and wet heat strain can be obtained. Further, it is possible to provide a toner sealing material having a performance in which the above preferable numerical value ranges of the respective characteristics are appropriately combined. Especially, the number of cells is 6
A toner seal material having an excellent performance balance of 5 pieces / 25 mm or more, air permeability of 100 seconds or more, CLD hardness of 5 kPa or less, and wet heat strain of 5% or less can be used.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to Examples and Comparative Examples. [1] Raw materials used (1) Polyether polyol (a) Bifunctional polyether polyol Product name "PP400", number average molecular weight; 400 Product name "PP600", number average molecular weight; 600 Product name "PP1000", number average molecular weight 1000 brand name "PP1500", number average molecular weight; 1500 brand name "PP2000", number average molecular weight; 2000 and above are all manufactured by Sanyo Kasei Co., Ltd. (B) Trifunctional polyether polyol, trade name "G300", number of functional groups; 3, number average molecular weight;
300 Product name "G700", number of functional groups; 3, number average molecular weight;
700 Product name "GP1000", number of functional groups; 3, number average molecular weight; 1000 Product name "GP1500", number of functional groups; 3, number average molecular weight; 1500

(2) Polyester polyol (a) Trifunctional polyester polyol manufactured by Dainippon Ink and Chemicals, Inc., trade name "ODX2"
518 ”, number average molecular weight; 3000, manufactured by Asahi Denka Kogyo Co., Ltd., trade name“ YT101 ”, number average molecular weight; 1000, manufactured by Kuraray Co., Ltd., trade name“ F2010 ”, number average molecular weight; 2000, manufactured by Asahi Denka Kogyo Co., Ltd. Name "F21-79", number average molecular weight; 2500, manufactured by Mitsui Takeda Chemical Co., Ltd., trade name "MN315"
0 ", number average molecular weight; 3150, manufactured by Mitsui Takeda Chemical Co., Ltd., trade name" MN400 "
0 ", number average molecular weight; 4000 (b) Bifunctional polyester polyol manufactured by Mitsui Takeda Chemical Co., Ltd., trade name" DIOL20 "
00 ", number average molecular weight; 2000

(2) Polyisocyanate: Crude MDI, manufactured by Nippon Polyurethane Co., Ltd., trade name "C1067", N
CO%; 31.3% (3) Foam stabilizer: Silicon foam stabilizer, manufactured by Nippon Unicar Co., Ltd., trade name "SZ1919" (4) Catalyst: amine catalyst, triethylenediamine, manufactured by Chukyo Yushi Co., Ltd., trade name " 33LV "(5) Foaming agent: water (ion-exchanged water)

[2] Manufacture of Flexible Polyurethane Foam According to the formulation shown in Table 1, each component except polyisocyanate was first agitated at a predetermined ratio using a hand mixer. Then, a polyisocyanate was blended according to a predetermined isocyanate index, and the mixture was put into a foam box and foamed and cured to produce a flexible polyurethane foam.

[0032]

[Table 1]

[3] Effect of type of polyol, etc. on physical properties (1) Amount ratio of polyester polyol and polyether polyol Examples 1 and 2 and Comparative Example 1 , Manufactured foam. The density, CLD hardness, wet heat strain, air permeability, number of cells and toner sealing property of the obtained foam were evaluated by the following methods. The results are also shown in Table 2. The evaluation criteria are shown in Table 3.

(A) CLD hardness; JIS K 6400
The hardness was measured by a hardness measuring instrument conforming to. The harder the foam (the larger the numerical value), the larger the repulsive force, and the frame or the like of the cartridge may be deformed to leak the toner. Therefore, the smaller the numerical value, the more preferable. (B) Wet heat strain (%); 50% foam with a thickness of 20 mm
Compress and place in a humid heat atmosphere at 70 ° C and 95% relative humidity for 24 hours
After exposure for a period of time, it was opened and the thickness was measured after 30 minutes. The wet heat strain is calculated by the following formula. Wet heat strain (%) = [(sample thickness before exposure to wet heat atmosphere-sample thickness after exposure to wet heat atmosphere) / sample thickness before exposure to wet heat atmosphere] x 100 The larger the value, the more difficult it is to restore. Poor sealing performance. The smaller the value, the better.

(C) Air permeability: Measured according to JIS L1096 B method. The higher the number, the lower the breathability,
Good sealability. (D) Number of cells: The number of cells per 25 mm length (cells / 25 mm) was measured with a microscope (manufactured by KEYENCE CORPORATION, model "VH-50"). The larger the value, the smaller the cell diameter and the better the sealing property.

(E) Toner sealing property: As shown in FIG. 1A, an O-shaped (ring-shaped or donut-shaped) punched sample 1 (thickness: 10 mm, inner diameter: 60 mm, outer diameter; 80)
(5 mm) of color toner 2 was put into the inner space (mm). Then, as shown in FIG. 1B, the sample 1 was sandwiched between the polypropylene film 3 and the acrylic resin plate 4. still,
The compressibility of sample 1 was 50%. Then, as shown in FIG. 1C, the sample was naturally dropped 20 times from a height of 30 mm. The depth of penetration of the toner 2 into the sample 1 after being dropped 20 times was measured with a caliper. The shallower the penetration depth, the better the sealing property.

[0037]

[Table 2] In addition, * represents that it is outside the scope of the present invention.

[0038]

[Table 3]

According to the results of Table 2, in Comparative Example 1 containing no polyester polyol, the wet heat strain is large, the number of cells is small (the cell diameter is large), the toner sealing property is “Δ”, and the toner sealing material is The overall evaluation as is "x". On the other hand, in Example 1, although the air permeability was “Δ”, other physical properties and the like were good, and it was found that together with Example 2, the toner sealing property was excellent and the balance of physical properties and the like was also good.

(2) Effect of Number Average Molecular Weight of Polyether Polyols Examples 3-5 and Comparative Examples 2-3 Polyols were blended as shown in Table 4 to produce foams,
Physical properties and the like were measured in the same manner as above, and the influence of the number average molecular weight of the polyether polyol was evaluated. The results are also shown in Table 4.

[0041]

[Table 4] In addition, * represents that it is outside the scope of the present invention.

According to the results of Table 4, the number average molecular weight is 40.
Comparative Example 2 using a polyether polyol as low as 0,
Also, in Comparative Example 3 using a polyether polyol having a high number average molecular weight of 2000, the wet heat strain was inferior, and the overall evaluation was “x”. On the other hand, in Examples 3 to 5 in which the polyether polyol has a number average molecular weight of 600 to 1500 and is within the range of the present invention, it is found that the toner sealing property is excellent and the balance of physical properties and the like is good.

(3) Effect of Number of Functional Groups and Number Average Molecular Weight of Polyester Polyol Examples 6 to 9 and Comparative Examples 4 to 5 Polyols were blended as shown in Table 5 to produce foams,
Physical properties and the like were measured in the same manner as above, and the influence of the number of functional groups and the number average molecular weight of the polyester polyol was evaluated. The results are also shown in Table 5.

[0044]

[Table 5] In addition, * represents that it is outside the scope of the present invention.

According to the results shown in Table 5, in Comparative Example 4 in which the polyester polyol having the number of functional groups of 3 and the molecular weight of 1000 was used, the CLD hardness value was large and the toner sealing property was inferior. Was "x". Further, in Comparative Example 5 in which the polyester polyol having the number of functional groups of 2 was used, the wet heat strain was very large, and the comprehensive evaluation was “x”. On the other hand, in Examples 6 to 9 using the polyester polyol having the number of functional groups of 3 and the molecular weight of 2000 to 4000, the toner sealing property was excellent.
It can be seen that the balance of physical properties and the like is also good.

(4) Effect of number average molecular weight and content of low molecular weight triols Examples 10 to 14 and Comparative Example 6 Polyols were blended as shown in Table 6 to produce foams,
The physical properties and the like were measured in the same manner as above, and the influence of the number average molecular weight and the content of the low molecular weight triol (using polyether polyol) was evaluated. The results are also shown in Table 6.

[0047]

[Table 6] In addition, * represents that the molecular weight of the low molecular weight triol exceeds the preferable range.

From the results shown in Table 6, it can be inferred that in Comparative Example 6 in which the low molecular weight triol has a large molecular weight of 1500, the toner sealing property is excellent, but the wet heat strain is large and the performance deteriorates with time. On the other hand, Examples 10 to 1 in which a low molecular weight triol having a preferable molecular weight range was blended
It can be seen that in No. 2, all the physical properties are good, the toner sealing property is excellent, and the balance of the physical properties is good.
In addition, in Example 11, Example 13 in which the content of the low molecular weight triol was changed to 40 parts by mass and 50 parts by mass.
It is also understood that Nos. 14 and 14 also have excellent physical properties and the like and have a good performance balance.

Furthermore, in the eleventh embodiment, the compression rate is set to 30.
% Or 40% to evaluate the toner sealability.
As a result, even if the compression ratio was changed in the range of 30 to 50%, no significant difference was found in the toner sealing property, and it was found that all were good.

In Example 11, the change in CLD hardness depending on the compression rate was evaluated. As a result, compression rate is 30%
4.5 kPa, 40% 4.6 kPa, compression rate 5
It was 4.8 kPa at 0%. The CLD hardness measured without compression is 4.5 kPa, and even if compressed by 30 to 50%, an appropriate hardness is maintained, and the toner leaks without deforming the cartridge frame or the like. It is presumed that this can be prevented.

[0051]

EFFECTS OF THE INVENTION According to the flexible polyurethane foam of the present invention, even when exposed to a harsh atmosphere, moderate hardness and excellent resistance to moisture and heat aging are not impaired, and sufficient toner sealing property is maintained for a long period of time. Maintained. Further, by using a specific low molecular weight triol as the polyol together, a foam having a lower hardness can be obtained, and even a fine toner does not deform the frame of the cartridge or the like, and surely leaks. Can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a method of measuring toner sealability.

[Explanation of symbols]

1; O-shaped punched sample, 2; color toner, 3; polypropylene film, 4; acrylic resin plate.

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Claims (7)

[Claims] 1. A polyurethane foam obtained by reacting a foam raw material containing a polyisocyanate and a polyol, wherein the polyol has 2 functional groups,
A polyether polyol having a number average molecular weight of 500 to 1800, a functional group number of 3, and a number average molecular weight of 15
A flexible polyurethane foam, which comprises a polyester polyol of from 0 to 4000. 2. The flexible polyurethane foam according to claim 1, wherein the polyol component contains at least one of a polyether polyol and a polyester polyol having a functional group number of 3 and a number average molecular weight of 250 to 1400. 3. The flexible polyurethane foam according to claim 1, wherein the polyisocyanate is diphenylmethane diisocyanate. 4. The flexible polyurethane foam according to claim 1, wherein the foam raw material contains an amine catalyst having no group that reacts with the polyisocyanate. 5. A toner sealing material comprising the flexible polyurethane foam according to any one of claims 1 to 4. 6. The flexible polyurethane foam has a cell number of 50 cells / 25 mm or more, and JIS L109.
6. The toner seal material according to claim 5, which has an air permeability of 3 seconds or more as measured according to the 6B method. 7. The CLD of the flexible polyurethane foam
Hardness is 10 kPa or less, and compressed by 50%, 70
The toner sealing material according to claim 6, which has a wet heat strain of 9% or less after being exposed to an atmosphere of ℃ and a relative humidity of 95% for 24 hours.