JP2011184640A - Soft polyurethane foam for toner sealing, and toner-sealing material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soft polyurethane foam for toner sealing having low hardness and air permeability, small compression set and excellent flame retardancy, and a toner-sealing material using it. <P>SOLUTION: The soft polyurethane foam for toner sealing is obtained by reacting a foam material containing polyol, polyisocyanate and a phosphorus-based liquefied flame retardant, and the polyol contains polyol (a) having a viscosity at 25°C of 15,000-30,000 mPa s and polyol (b) having a content of an ethylene oxide unit of 60 mass% or more. The content of the polyol (a) is 50-98 mass%, the content of polyol (b) is 2-23 mass% and the content of phosphorus determined by energy dispersive fluorescence X-ray analysis is 0.3-2.1 mass%. The toner-sealing material uses the foam for toner sealing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a flexible polyurethane foam for toner seal and a toner seal material using the same. More specifically, the present invention relates to a toner having fine flame resistance, low air permeability, low hardness and flexibility, low compression set, and excellent flame retardancy without using a halogen flame retardant. The present invention relates to a flexible polyurethane foam for sealing. The present invention also relates to a toner sealing material that uses this flexible polyurethane foam for toner sealing, has excellent sealing properties, and maintains excellent sealing properties even after aging.

  In image forming apparatuses such as various printers, a uniformly charged image carrier is selectively exposed to form a latent image, the latent image is visualized with toner, and the formed toner image is recorded on a recording medium. The image is recorded by transferring the image onto the image. In such an apparatus, toner must be replenished in a timely manner. To replenish the toner, a toner cartridge in which an image carrier, a charging device, a developing device, a cleaning device and the like are integrated is used. When the user attaches / detaches the cartridge to / from the apparatus main body, the toner can be replenished or the image carrier that has reached the end of its life can be replaced, and maintenance is easy. This process cartridge system is used in many image forming apparatuses. However, if toner leaks, an image defect occurs. Therefore, a resin such as a gap between the cartridge body frames and a gap between the developing sleeve of the developing device and the developing frame body is used. A toner seal material is interposed on the contact surface of the molded product. In addition, a toner sealant is interposed on the end portion side of the image carrier so that the waste toner does not leak into the gap between the end portion of the image carrier of the cleaning device and the waste toner holder.

  As the toner sealing material, various resin foams such as polyurethane foam, soft rubber, or various elastic bodies such as elastomer are used. In the case of resin foam, generally, a cell having fine cells, low air permeability, low hardness, softness, and excellent sealing properties is used. Often used resin foam is used. Furthermore, in order to obtain a foam having fine cells, it is necessary to use a polyol having a high viscosity. However, a polyether polyol, which is a general-purpose polyol, generally has a low viscosity, making it difficult to form fine cells, and sufficient sealing properties. It is difficult to obtain a foam having The toner seal material is also required to have characteristics such as a low compression set under wet heat and the like in order to increase the degree of freedom in design. Furthermore, in image forming apparatuses, excellent flame retardancy that passes the flame test standard for home appliances is required. In order to impart such high flame retardancy, halogen flame retardants have been used so far. It was a situation that had to be used.

  Also, a production method using a hydroxyl group-terminated prepolymer obtained by reaction of a polyether polyol and an isocyanate as a polyol component for the purpose of obtaining a polyurethane foam having fine cells as described above inexpensively and satisfactorily. Has been proposed (see, for example, Patent Document 1). Furthermore, a toner seal material using a flexible polyurethane foam obtained by reacting a foam material containing polyisocyanate, a specific polyether polyol and a polyester polyol is known as a soft toner seal material having a low hardness ( For example, see Patent Document 2.)

JP 2006-328295 A JP 2003-48944 A

  However, in the hot-pressed foam, the sealing material is too hard, the resilience elasticity becomes excessively large, and the resin molded product such as the frame of the cartridge main body may be deformed or cracked. In addition, the method for producing a polyurethane foam described in Patent Document 1 aims to obtain a hard foam raw material, does not mention flame retardancy at all, and does not describe use as a sealing material. Further, the toner seal material described in the cited document 2 may have low hardness and be flexible, but no consideration is given to flame retardancy.

  In addition, it is conceivable to divert an existing water-stopping foam for such applications, but this foam generally has a problem of high wet heat strain. The process cartridge or a product in which the process cartridge is incorporated is often transported by ship, but may be exposed to a severe atmosphere such as high temperature and high humidity during transportation. At that time, the toner seal material interposed in a compressed state between the frames of the cartridge body must maintain a repulsive force against compression for a long period of time. That is, the compression set must be small.

  The present invention solves the above-mentioned conventional problems, the cell is fine, the air permeability is low, the hardness is low and flexible, the compression set is small, and no halogen flame retardant is used. An object of the present invention is to provide a flexible polyurethane foam for toner seal (hereinafter sometimes abbreviated as “toner seal foam”) having excellent flame retardancy. Another object of the present invention is to provide a toner sealing material that uses this flexible polyurethane foam for toner sealing, has excellent sealing properties, and maintains excellent sealing properties even after elapse of time.

By using a specific polyol having a high viscosity in combination with a specific polyol containing a large amount of ethylene oxide units, and using a phosphorus-based liquid flame retardant such as a condensed phosphate ester flame retardant as a flame retardant, the cell becomes fine. Therefore, the foam for toner seal can be made to have excellent flame retardancy without using a halogen-based flame retardant, an inorganic flame retardant, or the like, having low breathability, low hardness, and flexibility. Further, by using this toner seal foam, a toner seal material having excellent sealing properties and the like can be obtained.
The present invention has been made based on such knowledge.

The present invention is as follows.
1. A flexible polyurethane foam for toner seal obtained by reacting a foam raw material containing a polyol, a polyisocyanate and a phosphorous liquid flame retardant, wherein the polyol has a viscosity at 25 ° C. of 15000 to 30000 mPa · s (a) And when the total amount of alkylene oxide units is 100% by mass, the content of ethylene oxide units is 60% by mass or more, and the polyol is 100% by mass. The content of the polyol (a) is 50 to 98 mass%, the content of the polyol (b) is 2 to 23 mass%, and the phosphorus content determined by energy dispersive X-ray fluorescence analysis is 0. A flexible polyurethane foam for toner seal, characterized by being 3 to 2.1% by mass.
2. 1. The phosphorus-based liquid flame retardant is a condensed phosphate ester-based flame retardant. Soft polyurethane foam for toner seals as described in 1.
3. The density measured by JIS K 7222 is from 17 to 27 kg / m ³ . Or 2. Soft polyurethane foam for toner seals as described in 1.
4). The above-mentioned 1. in which the measured hardness measured according to JIS K 6400 is 65 to 135N. To 3. The flexible polyurethane foam for toner seals according to any one of the above.
5. 1. The air flow rate measured according to JIS L 1096 8.27.1 [Method A (Fragile type method)] is 0.2 to 2.2 cm ³ / cm ² / sec. To 4. The flexible polyurethane foam for toner seals according to any one of the above.
6). JIS K 6400-4 4.5.2 The compression set as measured by the A method is 2.0 to 10.0%. To 5. The flexible polyurethane foam for toner seal according to any one of the above.
7). 2. The phosphorus content is 10 to 20% by mass when the condensed phosphate ester flame retardant is 100% by mass. To 6. The flexible polyurethane foam for toner seal according to any one of the above.
7). Above 1. To 7. A toner sealant comprising the soft polyurethane foam for toner seal according to any one of the above.

In the toner seal foam of the present invention, a polyol having a high viscosity and a polyol containing a large amount of ethylene oxide units are used as the foam raw material, and the cell is fine, the air permeability is low, the hardness is low, and the softness is low. Thus, it is possible to provide a toner sealing foam in which toner leakage is reliably prevented. Further, the compression set is small, and sufficient sealing performance is maintained even after aging. Furthermore, since the flame retardant is in a liquid state, even if blended in a larger amount, the compression set does not increase, and the toner seal foam has excellent flame retardancy that passes the combustion test standard for home appliances. be able to.
Further, when the phosphorus-based liquid flame retardant is a condensed phosphate ester-based flame retardant, it can be easily formed into a toner seal foam having low breathability, flexibility, and excellent flame retardancy. .
Furthermore, when the density measured according to JIS K 7222 is 17 to 27 kg / m ³ and when the hardness measured according to JIS K 6400 is 65 to 135 N, the air permeability is lower and the hardness is lower and flexible. And a toner seal foam having excellent sealing properties.
Further, when the air flow rate measured by JIS L 1096 8.27.1 [Method A (Fragile type method)] is 0.2 to 2.2 cm ³ / cm ² / sec, the leakage of the toner is more sufficiently prevented. Can be prevented.
Furthermore, when the compression set measured by the JIS K 6400-4 4.5.2 A method is 2.0 to 10.0%, sag over time is suppressed, and excellent sealing properties are maintained. A toner seal foam can be obtained.
Further, when the condensed phosphate ester flame retardant is 100% by mass and the phosphorus content is 10 to 20% by mass, the required amount of flame retardant can be easily added to the foam raw material. A toner seal foam containing a certain amount of phosphorus can be obtained.
Since the toner seal material of the present invention uses the foam for toner seal of the present invention, the compression set is small, and even when exposed to a harsh atmosphere, moderate hardness and excellent resistance to moist heat aging are impaired. And sufficient sealing performance is maintained even after aging. Moreover, it also has excellent flame retardancy that passes the combustion test standard for home appliances.

FIG. 3 is a schematic diagram for explaining a position where a toner cartridge is disposed in a printer which is a kind of image forming apparatus.

The present invention will be described in detail below.
[1] Soft polyurethane foam for toner seal The flexible polyurethane foam for toner seal of the present invention is obtained by reacting a foam raw material containing a polyol, a polyisocyanate and a phosphorus-based liquid flame retardant, and the polyol has a viscosity of 15000 at 25 ° C. Containing a polyol (a) of ˜30000 mPa · s and a polyol (b) having an ethylene oxide unit content of 60% by mass or more when the total amount of alkylene oxide units is 100% by mass, When the content is 100% by mass, the content of the polyol (a) is 50 to 98% by mass and the content of the polyol (b) is 2 to 23% by mass, which is determined by energy dispersive X-ray fluorescence analysis. The phosphorus content is 0.3-2.1% by mass.

As the “polyol”, a polyol (a) having a high viscosity and a polyol (b) having a high content of ethylene oxide units are used in combination. Also, the polyols (a) and (b) can be used in combination with at least one other polyol.
The “polyol (a)” is not particularly limited except that the viscosity at 25 ° C. is 15,000 to 30000 mPa · s and contained at a predetermined mass ratio. As the polyol (a), a hydroxyl-terminated prepolymer, a polyester polyol and a polyester ether polyol having a predetermined viscosity can be used.
The viscosity of the polyol (a) is a value measured with a B-type viscometer under the conditions of rotor number 4 and rotor rotation speed of 12 rotations / minute.

  The viscosity of the polyol (a) is preferably 17000 to 27000 mPa · s, particularly 18000 to 25000 mPa · s. Furthermore, content of a polyol (a) is 50-98 mass% when the whole quantity of a polyol is 100 mass%, It can be set as 60-95 mass%, especially 70-95 mass%. Further, the number of functional groups and the number average molecular weight of the polyol (a) are not particularly limited. The number of functional groups of the polyol (a) is usually 2 or 3, and the number average molecular weight is preferably 3000 to 15000, particularly 4000 to 14000. If the number average molecular weight of the polyol (a) is in the above range, particularly 4000 to 14000, a polyol having a predetermined viscosity can be easily obtained, the cell is fine, the air permeability is low, and the hardness is low. A toner seal foam which is flexible and has a small compression set can be obtained.

  The “polyol (b)” has an ethylene oxide unit (hereinafter abbreviated as “EO unit”) content of 60% by mass or more (100% by mass) when the total amount of alkylene oxide units is 100% by mass. And is not particularly limited except that it is contained at a predetermined mass ratio. The content of the polyol (b) is 2 in the case where the total amount of polyol is 100% by mass in order to obtain a flexible toner seal foam having fine cells, low air permeability, low hardness and flexibility. It is -23 mass%, and it is preferable that it is 3-15 mass%.

  The number of functional groups of the polyol (b) is not particularly limited, and is preferably 2 or 3, particularly 3. When the number of functional groups of the polyol (b) is 3, a toner seal foam having excellent flame retardancy and smaller compression set can be obtained. Furthermore, the number average molecular weight of the polyol (b) is not particularly limited, and is preferably 2000 to 5000, particularly 3000 to 4000. When the number average molecular weight of the polyol (b) is in the above range, particularly 3000 to 4000, it is possible to obtain a toner seal foam having excellent flame retardancy and smaller compression set.

  As the polyol, at least one other polyol other than the polyols (a) and (b) can be used in combination. Other polyols may be used alone or in combination of two or more. However, it is not necessary to use two or more in particular, and only one type is sufficient. Other polyols are not particularly limited, and general polyols such as polyether polyols and polyester polyols used for the production of flexible polyurethane foams can be used. As other polyols, when the total amount of alkylene oxide is 100% by mass, the content of EO units is less than 30% by mass, particularly 15% by mass or less, and further 10% by mass or less (EO unit is contained). The polyol may be omitted).

  The number of functional groups of other polyols is not particularly limited, and is preferably 2 or 3, particularly 3. If the number of functional groups of other polyols is 3, a toner seal foam having excellent flame retardancy and low compression set can be obtained. Further, the number average molecular weight of other polyols is not particularly limited, and is preferably 2000 to 5000, particularly 2000 to 4000. When the number average molecular weight of the other polyol is in the above range, particularly 2000 to 4000, a toner seal foam having excellent flame retardancy and a small compression set can be obtained. The other polyol has a content obtained by subtracting the total of the polyols (a) and (b) from the total amount when the total amount of the polyol is 100% by mass.

  As other polyols, in addition to the above-mentioned other polyols, at least polyether polyols and polyester polyols (hereinafter referred to as “low molecular weight triols”) having a functional group number of 3 and a number average molecular weight of 250 to 1400. One can also be used together. By using this low molecular weight triol in combination, the hardness can be further reduced. When the number of functional groups of other polyols used in combination is not 3, compression set tends to increase. If the number average molecular weight is less than 250, the hardness of the toner seal foam may not be sufficiently lowered. On the other hand, if it exceeds 1400, the compression set tends to increase.

  The number average molecular weight of the low molecular weight triol is preferably 250 to 1000, particularly preferably 250 to 700. By using such a low molecular weight triol in combination, a toner sealing foam having a smaller compression set can be obtained, and excellent sealing properties can be maintained even after aging. Further, as this low molecular weight triol, a polyether polyol is particularly preferable, and if it is a polyether polyol, a foam for toner seal can be obtained which has a sufficiently low hardness and a small compression set.

  Although content of a low molecular weight triol is not specifically limited, When the sum total of the polyol except a low molecular weight triol is 100 mass parts, it can be set to 10-60 mass parts, and it is preferable that it is 20-40 mass parts. . 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 lowered. On the other hand, when it exceeds 60 parts by mass, compression set tends to increase.

  Other polyols include polycarbonate-based polyols, polydiene-based polyols, etc. in addition to the above-mentioned specific polyols as long as the low air permeability and hardness of the toner seal foam and excellent compression set are not impaired. May be. These other special polyols may be used alone or in combination of two or more.

The “polyisocyanate” is not particularly limited, and polyisocyanates generally used for the production of flexible polyurethane foams can be used. As this polyisocyanate, toluene diisocyanate (TDI), crude TDI, 4,4′-diphenylmethane diisocyanate (MDI), crude MDI, and aromatic polyisocyanates such as 1,5-naphthalene diisocyanate and paraphenylene diisocyanate should be used. Can do. Furthermore, aliphatic polyisocyanates such as hexamethylene diisocyanate, hydrogenated MDI, and isophorone diisocyanate can also be used. In addition to these, a prepolymer type polyisocyanate can also be used.
Only one type of polyisocyanate may be used, or two or more types may be used in combination, but only one type is often used.
Moreover, a polyol and polyisocyanate can be used in the mass ratio from which an isocyanate index becomes 95-120, especially 100-115.

  As the “phosphorous liquid flame retardant”, organic phosphorus compounds such as phosphoric acid esters and polyphosphoric acids are used, and among these, phosphoric acid ester flame retardants, particularly condensed phosphoric acid ester flame retardants are preferable. When a liquid flame retardant is used, excellent compression set is not impaired, and deterioration of sealing properties with time is prevented. In addition, as the liquid flame retardant, there is a halogen-containing type containing halogen such as chlorine and bromine. However, since halogen has a problem in terms of environment, a phosphorous liquid flame retardant is used in the present invention.

  Examples of phosphate ester flame retardants include trimethyl phosphate, triethyl phosphate, tributyl phosphate, triisobutyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate and cresyl di-2,6-xylate. Nyl phosphate and the like can be mentioned.

In addition, examples of the condensed phosphate ester flame retardant which is a particularly preferable phosphate ester flame retardant include resorcinol bis-diphenyl phosphate, resorcinol bis-dixylenyl phosphate, and bisphenol A bis-diphenyl phosphate. The condensed phosphate ester flame retardant has a high molecular weight compared to the monomer type flame retardant, and thus hardly volatilizes and has a plasticizing action, so that the viscosity of the foam raw material can be appropriately reduced. Further, the mechanical strength or the like of the toner seal foam is not lowered.
Only one type of phosphorus-based liquid flame retardant may be used, or two or more types may be used in combination.

  By including a phosphorus-based liquid flame retardant in the foam raw material, phosphorus (phosphorus element) is contained in the produced toner seal foam. The phosphorus content is 0.3-2.1% by mass (100% by mass of the toner seal foam) as determined by energy dispersive X-ray fluorescence analysis, and 0.7-2. It is preferably 0.0% by mass. If the phosphorus content is 0.75 to 3.00% by mass, particularly 0.7 to 2.0% by mass, it has excellent flame retardancy that passes the combustion test standard for home appliances, and is compression permanent. A toner seal foam with sufficiently small distortion can be obtained.

When the condensed phosphate ester flame retardant is used, the content of phosphorus (phosphorus element) in the flame retardant is not particularly limited. However, when the condensed phosphate ester flame retardant is 100% by mass, phosphorus is 10 to 20%. It is preferable that it is contained by mass%, particularly 12-18 mass%. If the content of phosphorus in the condensed phosphate ester flame retardant is 10 to 20% by mass, by adding a predetermined amount of condensed phosphate ester flame retardant to the foam raw material, the phosphorus content as described above Can be used as a foam for toner seals having an amount of 0.3 to 2.1% by mass.
The phosphorus content in the condensed phosphate ester flame retardant can be quantified by energy dispersive X-ray fluorescence analysis.

The foam raw material contains a foaming agent, a catalyst, a foam stabilizer, and the like in addition to polyol, polyisocyanate, and phosphorus-based liquid flame retardant. Moreover, other auxiliary agents etc. can also be contained as needed.
As the foaming agent, water is usually used. This water is not particularly limited, and various waters such as ion exchange water, tap water, and distilled water can be used. The amount of water used for producing the toner seal foam can be 2 to 6 parts by mass, preferably 3 to 5 parts by mass, when the polyol is 100 parts by mass. When the amount of water is 2 to 6 parts by mass, a toner seal foam having a predetermined density, hardness, compression set, and the like can be obtained.

  As the catalyst, amine-based catalysts such as tertiary amine compounds such as triethylenediamine, triethylamine, N-methylmorpholine dimethylaminomethylphenol, imidazole, and 1,8-diazabicyclo [5,4,0] undecene can be used. In addition, a metal catalyst such as an organic tin compound such as stannous octoate or an organic nickel compound such as nickel acetylacetonate may be used. The catalyst is preferably an amine catalyst, particularly triethylenediamine. Only one type of catalyst may be used, or two or more types may be used in combination. The usage-amount of a catalyst can be 0.1-1.0 mass part when a polyol is 100 mass parts, and can be 0.2-0.5 mass part especially.

  As the foam stabilizer, a block copolymer of dimethylpolysiloxane and polyether can be used. Furthermore, a special foam stabilizer in which an organic functional group is added to polysiloxane can also be used. Thus, a silicone type foam stabilizer is often used as the foam stabilizer. Only one type of foam stabilizer may be used, or two or more types may be used in combination. The amount of the foam stabilizer used may be 0.5 to 2.0 parts by mass, particularly 0.8 to 1.5 parts by mass, when the polyol is 100 parts by mass.

Examples of the auxiliary agent used as necessary include antioxidants, ultraviolet absorbers, colorants, and various diluents for reducing the viscosity of the foam raw material to facilitate stirring and mixing. . These can be contained in appropriate amounts within a range in which the hardness, compression set, etc. of the toner seal foam are not impaired.
In addition, a foaming agent, a catalyst, a foam stabilizer, etc. are normally mix | blended with a polyol, and are mixed with polyisocyanate at the time of reaction.

  The method for producing the toner seal foam of the present invention is not particularly limited, and general methods for producing flexible polyurethane foam can be employed as they are. The toner seal foam does not chemically attack resin members such as a frame of the cartridge body (so-called chemical attack), and has an appropriate hardness and excellent resistance even when exposed to a harsh atmosphere. In addition, the wet heat aging resistance and the like are hardly deteriorated, excellent sealing performance is maintained for a long time, and toner leakage is sufficiently prevented.

[2] Toner Seal Material The toner seal material of the present invention is characterized by using the toner seal foam of the present invention.
With the toner sealant using the toner seal foam of the present invention, even if exposed to a harsh atmosphere, moderate hardness, excellent moist heat aging resistance, etc. are maintained over a long period of time, and compression set And the leakage of toner is sufficiently prevented. Further, even if the hardness is low and flexible, the sealing property is good, and the leakage of the toner can be sufficiently prevented by simply interposing it on the contact surface of the cartridge body and the like and compressing it appropriately. Therefore, the structure of the member such as the frame of the toner cartridge main body can be simplified, and the required resin amount can be reduced. Therefore, it is advantageous from the viewpoint of cost reduction.

The toner sealing foam as the toner sealing material has a cell number of 40 to 60/25 mm, particularly 40 to 55/25 mm, and a density measured according to JIS K 7222 of 17 to 27 kg / m ³ , particularly 20 ˜25 kg / m ³ , hardness measured according to JIS K 6400 is 65 to 135N, especially 70 to 130N, JIS L 1096 8.27.1 [Method A (Fragile type method)] has an air flow rate of 0.2 to 2.2 cm ³ / cm ² / second, especially 0.2 to 2.0 cm ³ / cm ² / second, and compression set measured by JIS K 6400-4 4.5.2 A method is 2.0 to 10 It is preferably 0.0%, particularly 3.0 to 9.0%. Such a toner seal foam can provide a toner seal material that has excellent sealing properties and maintains excellent sealing properties even after elapse of time. The toner sealant preferably passes a combustion test measured by UL-94 HF-1, and needs to pass a combustion test measured by UL-94 HF-2.

  The toner seal material of the present invention is, for example, a toner so that the toner 21 filled in the toner cartridge main body 2 incorporated in the printer 1 (see FIG. 1) which is a kind of image forming apparatus does not leak to the outside. It is used by being interposed between the frames of the cartridge body 2. Printing by the printer 1 is performed by attaching the toner 21 to the photosensitive drum 4 via the developing cylinder 3 and attaching the toner attached to the photosensitive drum 4 to the sheet by the transfer roller 5. In this case, the toner may leak from between the frames of the toner cartridge body 2 when used for a long period of time. However, if the toner seal material of the present invention is interposed between the frames, the toner leaks. It is sufficiently prevented.

Hereinafter, the present invention will be described specifically by way of examples.
Examples 1-6 and Comparative Examples 1-8
[1] Raw materials used (1) Polyol (A) Polyol (a): Hydroxyl-terminated prepolymer [manufactured by Sanyo Chemical Co., Ltd., trade name “FA-136” (viscosity: 20000 mPa · s, number average molecular weight; 12000, OH number; 33)]
(B) Polyol (b): Polyether polyol [manufactured by Sanyo Chemical Co., Ltd., trade name “FA-103” (EO unit content: 80% by mass, viscosity: 720 mPa · s, number average molecular weight; 3400, number of functional groups; 3 OH value; 60)]
(C) Polyols other than polyols (a) and (b) (c): Polyether polyol [manufactured by Sanyo Kasei Co., Ltd., trade name “GP-3050NS” (EO unit content: 8 mass%, viscosity: 500 mPa · s] s, number average molecular weight; 3000, number of functional groups; 3, OH value; 56.1)]
(2) Foaming agent: water (ion exchange water)
(3) Catalyst: Amine-based catalyst (trade name “Kaolinizer No. 81” manufactured by Kao Corporation)
(5) Foam stabilizer: Silicone foam stabilizer (manufactured by Toray Dow Corning, trade name “SZ-1919”)
(6) Flame retardant (A) Phosphorus liquid flame retardant: Condensed phosphate ester flame retardant [manufactured by Daihachi Chemical Co., Ltd., trade name “D-880” (phosphorus content: 15 mass%)]
(B) Powdery flame retardant (a): Melamine (Mitsui Chemicals, trade name “melamine”)
(C) Powdered flame retardant (b): expanded graphite (manufactured by Sanyo Trading Co., Ltd., trade name “SYZR 502FP”)
(7) Polyisocyanate: TDI [manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name “Tes Module T-80” (2,4-isomer ratio: 80%)]

[2] Manufacture of Toner Seal Foam First, each component excluding polyisocyanate is handed at a predetermined quantitative ratio according to the formulation described in Table 1 (Examples 1 to 6) and Table 2 (Comparative Examples 1 to 8). Stir using a mixer. Thereafter, polyisocyanate was blended according to a predetermined isocyanate index, and this mixture was put into a foaming box and foamed and cured to produce a toner seal foam.

[3] Characteristic evaluation The number of cells of the toner seal foam produced in the above [2] was measured by the following method. The phosphorus content was measured by the above method. Furthermore, density, hardness, air flow rate and compression set were measured by the following methods, and flame retardancy was evaluated by the following methods. The results are shown in Tables 1 and 2.

(A) 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 numerical value, the smaller the cell diameter, the finer the cell, and the better the sealing performance.
(B) Density: Measured according to JIS K 7222.
(C) Hardness: Measured according to JIS K 6400.
(D) Aeration rate: Measured according to JIS L 1096 8.27.1 [Method A (Fragile type method)]. The smaller the value, the lower the air permeability and the better the sealing performance.
(E) Compression set: Measured by JIS K 6400-4 4.5.2 A method. The smaller the value, the less the sag when used for a long time in an environment such as wet heat, and the sufficient sealing performance is maintained.
(F) Flame retardancy; measured and evaluated by a combustion test of UL-94 HF-1.
In Tables 1 and 2, “6 mm” means that the test piece passed when measured using a test piece having a thickness of 2.0 to 6.0 mm.

According to Table 1, the toner seals of Examples 1 to 7 using a high-viscosity hydroxyl-terminated prepolymer and a polyol having a high content of EO units and a foam raw material containing a condensed phosphate ester flame retardant In the foam for use, the cell is fine, the air flow rate is 1.89 cm ³ / cm ² / sec or less, the density and hardness are low, the compression set is small, and the sealing property is excellent. It is presumed that the sealing performance is maintained even after aging. Moreover, all are passing in a combustion test.

  On the other hand, according to Table 2, in Comparative Example 1 in which the polyol (a) is not contained, the number of cells is small (the cell diameter is large), the air flow rate is extremely large, and the polyol (a) is less than the lower limit value. Also in Example 2, the number of cells is slightly small, the air flow rate is large, and all have large compression set. In Comparative Example 3 in which phosphorus is insufficient, the combustion test is rejected. In Comparative Example 4 in which phosphorus is excessive, the combustion test is passed, but the compression set is considerably increased. Furthermore, in Comparative Examples 5 and 6 using a powdered flame retardant, the density is high and hard, and the compression set is considerably large, which is a problem. Further, in Comparative Example 7 in which the polyol having a high content of EO units is not contained, in the comparative example 8 in which the foam shrinks, the foam is not generated, and the polyol having a high content of EO units is excessive. As the air flow increases, the compression set is considerably large, which is a problem.

  The present invention is useful in the field of toner seal materials used in electrophotographic image forming apparatuses, for example, process cartridges mounted on various printers, facsimiles, copiers, and the like.

  DESCRIPTION OF SYMBOLS 1; Printer, 2; Toner cartridge main body, 21; Toner, 3; Developing cylinder, 4; Photosensitive drum, 5;

Claims (8)

A flexible polyurethane foam for toner seal obtained by reacting a foam raw material containing a polyol, a polyisocyanate and a phosphorous liquid flame retardant,
The polyol has a viscosity of 15,000 to 30000 mPa · s at 25 ° C. and a polyol having an ethylene oxide unit content of 60% by mass or more when the total amount of alkylene oxide units is 100% by mass. (B) and
When the polyol is 100% by mass, the content of the polyol (a) is 50 to 98% by mass, the content of the polyol (b) is 2 to 23% by mass,
A flexible polyurethane foam for toner seal, wherein the phosphorus content determined by energy dispersive X-ray fluorescence analysis is 0.3 to 2.1% by mass.   The flexible polyurethane foam for toner seal according to claim 1, wherein the phosphorous liquid flame retardant is a condensed phosphate ester flame retardant. ^{3. The} flexible polyurethane foam for toner seal according to claim 1, wherein the density measured by JIS K 7222 is 17 to 27 kg / m ³ .   The flexible polyurethane foam for toner seal according to any one of claims 1 to 3, having a hardness measured according to JIS K 6400 of 65 to 135N. The air flow rate measured according to JIS L 1096 8.27.1 [Method A (Fragile type method)] is 0.2 to 2.2 cm ³ / cm ² / sec. Soft polyurethane foam for toner seals as described in 1.   The flexible polyurethane foam for toner seal according to any one of claims 1 to 5, wherein the compression set measured by JIS K 6400-4 4.5.2 A method is 2.0 to 10.0%. .   The flexible polyurethane foam for toner seal according to any one of claims 2 to 6, wherein the content of phosphorus is 10 to 20% by mass when the condensed phosphate ester flame retardant is 100% by mass. .   A toner sealant comprising the soft polyurethane foam for toner seal according to any one of claims 1 to 7.

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