JP6509476B1 - Polyurethane elastomer composition, method of manufacturing cleaning blade and cleaning blade - Google Patents

Abstract

The present invention provides a polyurethane elastomer composition capable of achieving both improvement in pot life and vulcanization characteristics while maintaining material properties required for a cleaning blade, a method of manufacturing a cleaning blade and a cleaning blade. A polyurethane elastomer composition comprising a cast-type polyurethane elastomer and used for a cleaning blade, comprising a bifunctional polyol, a polyisocyanate, a curing agent, and an imidazole compound that promotes a urethanization reaction. It comprises a positive catalyst, a negative catalyst which is a carboxylic acid compound which limits the catalytic ability of the positive catalyst depending on the temperature, and a blocking agent which protects the isocyanate group of the polyisocyanate. 【Selection chart】 None

Description

  The present invention relates to a polyurethane elastomer composition, a method of manufacturing a cleaning blade and a cleaning blade.

  Generally, in the electrophotographic process, at least cleaning, charging, exposure, development and transfer processes are performed on an electrophotographic photosensitive member. In each process, a cleaning blade for removing and cleaning the toner remaining on the surface of the photosensitive drum, a conductive roll for uniformly charging the photosensitive member, and a transfer belt for transferring a toner image are used. And a cleaning blade is mainly manufactured by thermosetting polyurethane resin from a viewpoint of plastic deformation, abrasion resistance, etc.

  The polyurethane cleaning blade is manufactured, for example, using a polyisocyanate, a polyol, a curing agent, a catalyst, and other necessary components by a method such as a prepolymer method, a semi one shot method, a one shot method and the like.

  For example, when manufacturing a cleaning blade using a prepolymer method, a mold (mold) for the cleaning blade is prepared, and a liquid composition as a raw material of the polyurethane resin is injected into the mold. Next, by curing (urethaneizing) the liquid composition in the mold, the resulting cured product is demolded to obtain a cured polyurethane product. Finally, the resulting polyurethane cured product is formed into a predetermined size, and a metal fitting as a support is attached to obtain a cleaning blade. In the prepolymer method, for example, a prepolymer in which polyisocyanate and polyol are partially polymerized is prepared, and a curing agent, a catalyst, and other necessary components are added to the prepolymer to prepare a liquid composition. Do.

  In the production of the cleaning blade by the prepolymer method, the pot life (solidification time from mixing of each raw material to solidification of the liquid composition and impossibility of injection) and curing time greatly affect production efficiency. If the curing time is long, a large investment is required due to the increase in the number of molds and the like. For this reason, various studies have been made on a method of shortening the curing time (for example, Japanese Patent No. 4855360 (Patent Document 1), Japanese Patent No. 4855360 (Patent Document 2), Japanese Patent Application Laid-Open No. 2007-178773 (Patent Document) 3) Patent 5,492,746 (patent document 4).

  As a method of shortening the curing time of the liquid composition, the addition of a catalyst is common. As a general-purpose catalyst in the urethanization reaction, amine catalysts such as triethylenediamine (TEDA) and dimethylimidazole (DMIZ) are known. In the prepolymer method, when a general-purpose catalyst having a conventional catalytic amount is used, although the curing time is shortened, there is a problem that the pot life is short and the processability is inferior. On the other hand, when the liquid temperature is lowered to suppress the reaction activity, the viscosity of the liquid composition becomes high, which causes a problem that the workability and the yield deteriorate.

  When it is desired to further shorten the curing time, the reaction rate of the liquid composition also increases with the increase of the amount of catalyst. Then, the increase in viscosity of the liquid composition makes it difficult to inject the required amount of the liquid composition into the mold. There is also the problem that polyurethane chips cured in the pre-injection stage mix into the liquid composition. In any case, increasing the amount of catalyst may lead to an increase in defective products. In addition, there is also a problem that the increase in viscosity of the liquid composition makes it impossible to produce large-sized products.

  In view of such circumstances, the present invention maintains a material property required for a cleaning blade and, at the same time, improves a pot life and a vulcanizing property, a polyurethane elastomer composition, a method for producing the cleaning blade, and The purpose is to provide a cleaning blade.

  A first aspect of the present invention for solving the above-mentioned problems is a polyurethane elastomer composition comprising a cast-type polyurethane elastomer and used for a cleaning blade, comprising: a bifunctional polyol, a polyisocyanate, a curing agent, a urethane A positive catalyst which is an imidazole compound which promotes the esterification reaction, a negative catalyst which is a carboxylic acid compound which limits the catalytic ability of the positive catalyst according to the temperature, and a blocking agent which protects the isocyanate group of the polyisocyanate It is a polyurethane elastomer composition characterized by including.

  Another aspect of the present invention is a method for producing a cleaning blade using a cast-type polyurethane elastomer obtained from a polyurethane elastomer composition, which promotes a bifunctional polyol, a polyisocyanate, a curing agent, and a urethanization reaction. Polyurethane which is a mixed liquid by mixing a positive catalyst which is an imidazole compound, a negative catalyst which is a carboxylic acid compound which limits the catalytic ability of the positive catalyst according to temperature, and a blocking agent which protects the isocyanate group of the polyisocyanate A method of manufacturing a cleaning blade comprising: preparing the elastomer composition; and forming the cleaning blade from a polyurethane elastomer which is a cured product obtained by curing the mixed liquid by casting. It is.

  Yet another aspect of the present invention is a cleaning blade characterized in that it is a molded article of a cured product of the polyurethane elastomer composition of the embodiment of the present invention.

  According to the present invention, there is provided a polyurethane elastomer composition capable of achieving both improvement in pot life and vulcanization characteristics while maintaining the material properties required for the cleaning blade, and a method of manufacturing the cleaning blade and the cleaning blade. be able to.

It is a sectional view showing an example of a cleaning blade concerning an embodiment of the present invention. It is the graph which showed the relationship between the vulcanization time of each sample, and solidification time.

  The polyurethane elastomer composition according to the embodiment of the present invention will be described in detail below. In the present embodiment, although a case where a polyurethane elastomer composition is used for a cleaning blade of an image forming apparatus is described as an example, an application example of the polyurethane elastomer composition is not limited to the cleaning blade.

(Embodiment 1)
(Cleaning blade)
FIG. 1 is a cross-sectional view showing an example of a cleaning blade according to an embodiment of the present invention. As shown in FIG. 1, the cleaning blade 1 includes a blade main body (which is also referred to as a cleaning blade) 10 and a support member 20, and the blade main body 10 and the support member 20 are attached via an adhesive (not shown). It is joined. The blade body 10 is composed of an elastic body 11 which is a molded body of a rubber base (polyurethane).

  The elastic body 11 constituting the blade main body 10 is made of a castable polyurethane elastomer. The polyurethane elastomer is a cured product of a polyurethane elastomer composition. The cast-type polyurethane elastomer is a polyurethane elastomer obtained by processing a polyurethane elastomer composition by cast molding. A polyurethane elastomer is molded to form an elastic body 11 (molded body) that constitutes the blade main body 10. Such polyurethane elastomer compositions include bifunctional polyols, polyisocyanates, curing agents, positive catalysts, negative catalysts, blocking agents, and other necessary components.

  The bifunctional polyol applicable in the present embodiment is a long chain polyol, and examples thereof include a polyester polyol, a polycarbonate polyol obtained by the reaction of a diol and an alkyl carbonate, a caprolactone-based polyol, a polyether polyol and the like. The long chain polyol preferably has a number average molecular weight of 1000 to 4000, more preferably 1000 to 3000, and particularly preferably 1000 to 2000. These bifunctional polyols may be used alone or in combination of two or more.

  Specific examples of the polyisocyanate include 4,4'-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (H-MDI), trimethylhexamethylene diisocyanate (TMHDI), tolylene diisocyanate (TDI), polymethylene polyphenyl polyisocyanate, 3,3'-dimethylbiphenyl-4,4'-diyl diisocyanate (TODI), naphthyl diisocyanate (NDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HDI) Paraphenylene diisocyanate (PPDI), lysine diisocyanate methyl ester (LDI), dimethyl diisocyanate (DDI), etc. It may be a multimer, a modified form or the like. In addition, these polyisocyanates may be used alone or in combination of two or more. Among these, MDI and TODI are preferably used from the viewpoint of strength and wear resistance.

  In the present embodiment, a urethane prepolymer in which at least a part of the bifunctional polyol and the polyisocyanate is prepolymerized may be used. Here, the urethane prepolymer is an unvulcanized compound obtained by partially polymerizing (forming a urethane bond) by advancing the urethanization reaction of a bifunctional polyol and a polyisocyanate to a certain extent. The end of the urethane prepolymer is an isocyanate group (-N = C = O), and the end group (NCO end) is reacted with a curing agent (forming a urethane bond) to form a polyurethane elastomer. The bifunctional polyol and the polyisocyanate can stabilize the quality of the polyurethane elastomer composition by forming a urethane prepolymer in which the urethanation reaction has been advanced to a certain extent in advance. As a result, such a polyurethane elastomer composition can be used to produce a high quality cleaning blade 1.

  When such a urethane prepolymer is used, the polyurethane elastomer composition is prepared so as to contain other bifunctional polyols and polyisocyanates as needed together with the predetermined urethane prepolymer. Therefore, in the present specification, "a polyurethane elastomer composition includes a bifunctional polyol and a polyisocyanate" is a concept including the case where at least a part of the bifunctional polyol and the polyisocyanate is a urethane prepolymer.

  The curing agent is not particularly limited as long as it is a low molecular weight polyol (short chain polyol) having a number average molecular weight of 500 or less, and a bifunctional polyol, a polyhydric alcohol or the like can be used. These curing agents may be used alone or in combination of two or more.

  Examples of difunctional low molecular weight polyols include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), 1,3-propanediol (PD), 1,4-butanediol (BD), 1,5- Pentanediol, 1,6-hexanediol (HD), 1,4-cyclohexanediol, paraxylylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene (BHEB) and the like can be mentioned. Among these bifunctional polyols, it is preferable to use one having a molecular weight of 200 or less because a cured product of a highly hard polyurethane elastomer composition can be produced.

  As polyhydric alcohols, trifunctional fatty acids such as glycerin, 1,2,4-butanetriol, trimethylolethane (TME), 1,1,1-trimethylolpropane (TMP), 1,2,6-hexanetriol, etc. Group polyol; polyether triol obtained by adding ethylene oxide, butylene oxide etc. to trifunctional aliphatic polyol; polyester triol obtained by adding lactone etc. to trifunctional aliphatic polyol; tetrafunctional aliphatic polyol etc. such as diglycerin (diglycerol) It can be mentioned. Among these polyhydric alcohols, those having a molecular weight of 300 or less are preferably used. By containing a polyhydric alcohol having a molecular weight of 300 or less, a polyfunctional hydroxyl group reacts with an isocyanate group, and an elastic body 11 with a high crosslinking density having a three-dimensional network structure can be obtained.

  Among the above, bifunctional polyols such as 1,4-butanediol (BD) and polyhydric alcohols such as 1,1,1-trimethylolpropane (TMP) and diglycerin (diglycerol) are preferable. It is further preferable to use in combination.

  The positive catalyst is to promote the urethanization reaction. It will not be specifically limited if it is such a catalyst, For example, a tertiary amine catalyst can be mentioned. Specifically, aminoalcohols such as dimethylethanolamine; trialkylamines such as triethylamine; tetraalkyldiamines such as N, N, N ', N'-tetramethyl-1,3-butanediamine; TEDA, piperazine type, A triazine type, an imidazole type compound, etc. can be used. Examples of the imidazole compound include 1-methylimidazole, 1-isobutyl-2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole and the like. Among these, 2-ethyl-4-methylimidazole is preferred.

  A negative catalyst is one that is capable of limiting the catalytic capacity of the positive catalyst depending on the temperature. Specifically, when the liquid temperature of the polyurethane elastomer composition is lower than the initiation temperature of the curing reaction (urethane formation reaction), that is, at the time of uncuring reaction (for example, at room temperature), salts (complexes) with negative catalyst and positive catalyst. To limit the catalytic ability of the positive catalyst to inhibit the urethanization reaction. On the other hand, when the liquid temperature of the polyurethane elastomer composition is equal to or higher than the start temperature of the urethanization reaction, ie, at the time of curing reaction (for example, at high temperature of 120 ° C. to 200 ° C.), the complex is dissociated by heat and the positive catalyst has catalytic activity. Promote the urethanization reaction to exert That is, the negative catalyst imparts temperature sensitivity that suppresses or accelerates the urethanation reaction according to the liquid temperature of the polyurethane elastomer composition. By using a negative catalyst that imparts temperature sensitivity, the pot life (solidification time from mixing of each material to solidification of the polyurethane elastomer composition and impossibility of injection) can be extended. In addition, the time (vulcanization time) required for the polyurethane elastomer composition to reach the optimum vulcanization point (t90) can be shortened. Therefore, the combined use of the negative catalyst and the positive catalyst can achieve both improvement in pot life and vulcanization characteristics.

  The negative catalyst is not particularly limited as long as it can limit the catalytic ability of the positive catalyst according to the temperature as described above. For example, a carboxylic acid compound such as a hydroxy acid can be used. These negative catalysts may be used alone or in combination of two or more.

  As a hydroxy acid, glycolic acid, lactic acid, talthronic acid, glyceric acid, hydroxybutyric acid (2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-hydroxybutyric acid), malic acid, tartaric acid (2,3-dihydroxybutanedioic acid), Aliphatic hydroxy acids such as citralamic acid, citric acid, isocituric acid, leucine acid, mevalonic acid, pantoic acid, ricinoleic acid, ricineridic acid, cerebronic acid, quinic acid, shikimic acid; salicylic acid, creosote acid (homosalicylic acid, hydroxy ( Monohydroxybenzoic acid derivatives such as methyl) benzoic acid), vanillic acid, and silicic acid; Dihydroxybenzoic acid derivatives such as pyrocatechuic acid, resorcylic acid, protocatechuic acid, gentisic acid, andrusenic acid; Trihydroxybenzoic acid derivatives such as gallic acid Mandelic acid, benzyl acid, at Phenylacetic acid derivatives such as Rakuchin acid; Meriroto acid, phloretic acid, coumaric acid, umbellic acid, caffeic acid, ferulic acid, aromatic hydroxy acids such as cinnamic acid derivatives or hydrocinnamic acid derivatives such sinapinic acid. Among these, tartaric acid (2,3-dihydroxybutanedioic acid) is preferred.

  The blocking agent is capable of protecting (blocking) the isocyanate group of the polyisocyanate to limit the progress of the urethanization reaction. By using such a blocking agent, when the liquid temperature of the polyurethane elastomer composition is less than the initiation temperature of the curing reaction (urethane reaction), the isocyanate group is protected, and the urethane reaction can be suppressed. As a result, the pot life can be improved (solidification time can be extended). When the liquid temperature of the polyurethane elastomer composition is equal to or higher than the start temperature of the urethanization reaction, the blocking agent does not participate in the urethanization reaction and does not inhibit the reaction.

  As blocking agents, active methylene compounds such as malonic acid and 2,4-pentanedione (acetylacetone); methanol, ethanol, isopropanol, n-butanol, 2-ethoxyhexanol, 2-N, N-dimethylaminoethanol, 2- Alcohols such as ethoxyethanol and cyclohexanol; phenols such as phenol, o-nitrophenol, p-chlorophenol, o-cresol, m-cresol, and p-cresol; lactams such as ε-caprolactam; acetone oxime, methyl ethyl ketone Oximes such as oxime, methyl isobutyl ketone oxime, cyclohexanone oxime, acetophenone oxime, benzophenone oxime and the like; pyrazoles such as pyrazole, 3,5-dimethylpyrazole and 3-methylpyrazole Lumpur like; dodecanethiol, and thiols such as benzene thiol. Among these, 2,4-pentanedione (acetylacetone) is preferable. These blocking agents may be used alone or in combination of two or more.

  The polyurethane elastomer composition can optionally contain an organic solvent. The organic solvent is not particularly limited as long as it dissolves each component of the polyurethane elastomer composition, but one having no active hydrogen capable of reacting with polyisocyanate is suitably used. Examples of such organic solvents include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF), acetone, ethyl acetate, butyl acetate, toluene, xylene and the like. Among these, methyl ethyl ketone (MEK), acetone and ethyl acetate are preferable.

  The polyurethane elastomer composition may also contain other components as required. As another component, a hydrolysis inhibitor, an antiaging agent, etc. are mentioned, for example.

  In addition, the compounding ratio of each component in a polyurethane elastomer composition may be suitably designed according to the material characteristic requested | required of the cleaning blade 1 (blade main body 10). From the viewpoint of the function of the cleaning blade, the hardness (JIS A) of the polyurethane elastomer composition is preferably adjusted to be 60 to 80.

  The polyurethane elastomer composition is a mixture prepared by the above-described formulation, but may be obtained by mixing two separately prepared solutions. In this case, the liquid mixture (polyurethane elastomer composition) comprises a first liquid (also referred to as liquid A) containing a bifunctional polyol and a polyisocyanate, and a second liquid (also referred to as liquid B) containing a curing agent and a negative catalyst. It is obtained by mixing. The liquid mixture (polyurethane elastomer composition) obtained by any method can be cured to form a cured product (polyurethane elastomer), and it can be molded to produce the blade body 10 of the cleaning blade 1. Incidentally, at least a part of the bifunctional polyol and the polyisocyanate may be a urethane prepolymer.

  The positive catalyst may be contained in either one of the first liquid and the second liquid, and in particular, is preferably contained in the second liquid. This is because when the positive catalyst alone is added to the first solution, the activity of the isocyanate group (-N = C = O) of the polyisocyanate is enhanced, and the progress of the side reaction (isocyanate dimerization) and the deactivation by water (urea And the storage stability of the first solution is aggravated.

  Therefore, from the viewpoint of suppressing the progress of side reactions and urea conversion, the negative catalyst is preferably contained in the second solution containing a positive catalyst. When tartaric acid, for example, is used as the negative catalyst, high melting point tartaric acid is difficult to dissolve in the first liquid, and the liquid temperature of the polyurethane elastomer composition becomes urethane when mixing the first liquid and the second liquid. When it is below the reaction initiation temperature, it becomes difficult to limit the catalytic ability of the positive catalyst.

  Moreover, if the liquid temperature of a polyurethane elastomer composition is less than the start temperature of a curing reaction (urethane formation reaction), a block agent will not restrict | limit the addition method, if progress of a urethane formation reaction can be restrict | limited. That is, the blocking agent may be contained in any one of the first liquid and the second liquid, and may be contained in both the first liquid and the second liquid as needed. Alternatively, a separately prepared blocking agent may be added at the time of mixing of the first and second liquids to form a mixed liquid.

  In addition, the surface treatment layer 12 which has the predetermined thickness t may be formed in the surface layer part of the elastic body 11. The surface treatment layer 12 can be formed, for example, by impregnating the surface layer portion of the elastic body 11 with a surface treatment liquid and curing. The surface treatment layer 12 may be a cured product containing polyisocyanate contained in the surface treatment liquid, which has reacted with the polyol component of the elastic body 11. The surface treatment layer 12 may be formed, for example, at least in a portion in contact with the cleaning target of the elastic body 11.

  The surface treatment liquid used to form the surface treatment layer 12 contains, for example, polyisocyanate and an organic solvent. As the polyisocyanate and the organic solvent contained in the surface treatment liquid, those described above can be applied. In addition, the surface treatment liquid may contain other components as needed.

  The surface treatment layer 12 formed by using such a surface treatment solution has high hardness and low friction even if it is thin, and is excellent in scuff resistance, filming suppression property and cleanability. The surface treatment liquid is appropriately selected in consideration of the wettability to the elastic body 11, the degree of immersion, and the effective period of the surface treatment liquid.

(Method of manufacturing cleaning blade)
The method of manufacturing the cleaning blade 1 according to the embodiment of the present invention uses a castable type polyurethane elastomer obtained from the above-described polyurethane elastomer composition. Here, the method for producing the cleaning blade is not particularly limited, but, for example, a polyurethane obtained by mixing a bifunctional polyol, a polyisocyanate, a curing agent, a positive catalyst, a negative catalyst, a blocking agent, and other necessary components. The polyurethane elastomer composition may be a one-part curing type (hereinafter referred to as "first manufacturing method") using the elastomer composition, or two parts containing each component may be prepared and mixed to be a mixed liquid. It may be a two-component curing type (hereinafter referred to as "the second production method") using a substance.

  For example, the first production method comprises: preparing a polyurethane elastomer composition which is a mixed liquid by mixing a bifunctional polyol, a polyisocyanate, a curing agent, a positive catalyst, a negative catalyst, and a blocking agent; Forming a cleaning blade from a polyurethane elastomer which is a cured product obtained by curing a liquid by casting.

  The second production method comprises a first preparation step of preparing a first liquid containing a bifunctional polyol and a polyisocyanate, and a second liquid containing a curing agent which is a short chain polyol and a negative catalyst which is a carboxylic acid compound. A second preparation step to prepare, a third preparation step to prepare a polyurethane elastomer composition which is a mixed liquid by mixing the prepared first and second liquids, and curing the prepared liquid mixture by casting And a molding step of molding the blade main body 10 (cleaning blade 1) from the polyurethane elastomer which is a cured product obtained.

  The first production method and the second production method use the prepolymer method, and after mixing the prepared mixture with a pouring machine, it is compressed and poured into a mold (mold), and the metal fitting (blade body 10 Although an integrally formed injection machine that can be integrally formed with the support member 20) which is a holder may be applied, it is not limited thereto. For example, in addition to the prepolymer method, methods such as semi-one-shot method, one-shot method may be used, or integration of the blade main body 10 and the support member 20 obtained by the molding process may be performed using other devices. It may be done.

  In these production methods, at least a part of the bifunctional polyol and the polyisocyanate may be a urethane prepolymer. When a urethane prepolymer is used in the second production method, the timing of urethane prepolymerization of the bifunctional polyol and polyisocyanate is not particularly limited, but may be performed, for example, in the first preparation step and the third preparation step . The degree of progress of the reaction of the bifunctional polyol and the polyisocyanate (the degree of polymerization of the monomers) can be controlled by adjusting the reaction temperature and the reaction time.

  In the molding step of these manufacturing methods, the curing temperature when curing the obtained polyurethane elastomer composition into an elastomer can be appropriately changed according to the material properties required for the cleaning blade 1 (blade main body 10) However, for example, it is preferable to set the temperature to 120 ° C. to 200 ° C.

  The polyurethane elastomer composition of the present invention comprises a bifunctional polyol, a polyisocyanate, a curing agent, a positive catalyst, a negative catalyst, a blocking agent, and other necessary components. In addition, the polyurethane elastomer composition of the present invention uses a positive catalyst that promotes the urethanization reaction and a negative catalyst that can limit the catalytic ability of the positive catalyst according to the temperature, and an isocyanate according to the temperature. Since the block agent capable of protecting the group is included, it is possible to maintain the material properties required for the cleaning blade and to achieve both improvement in pot life and vulcanization properties.

  EXAMPLES The present invention will be described by way of examples, which should not be construed as limiting the invention.

(Sample 1)
An ester-based polyol (Polylite CT-4117, manufactured by DIC Corporation) as a bifunctional polyol and 4,4'-diphenylmethane diisocyanate (Cosmonate PH, manufactured by Mitsui Chemicals, Inc.) as a polyisocyanate are shown in Table 1 below. It was made to mix and react by the mixture ratio shown. Thereafter, the temperature was adjusted to 80 ° C. to obtain a mixed solution of NCO-terminated prepolymer and polyisocyanate (Liquid A).

  As a curing agent, 1,4-butanediol (Mitsubishi Chemical Corporation, 1,4 Butanediol), 1,1,1-trimethylolpropane (Gronei Chemical Industries, Ltd., Trimethylolpropane) and diglycerol (Sakamoto Yakuhin Kogyo Co., Ltd. Ltd., diglycerin S), 2,4-pentanedione as a blocking agent (Acetylacetone, manufactured by Tokyo Chemical Industry Co., Ltd.), 2-ethyl-4-methylimidazole as a positive catalyst (Mitsubishi Chemical Co., Ltd., jER) After curing CURE (registered trademark) EMI 24 was added at the mixing ratio shown in Table 1 below and dissolved at 80 ° C., 2,3-dihydroxybutanedioic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a negative catalyst. The tartaric acid was added at the mixing ratio shown in Table 1 below, and stirred until dissolved. Thereafter, the mixture was naturally cooled to room temperature to obtain a mixed solution (Liquid B).

  The obtained solution A and solution B were used as sample 1.

(Samples 2 to 9)
The solutions A and B were prepared in the same manner as the sample 1 except that they were prepared at the mixing ratio shown in Table 1 below, and they were respectively designated as samples 2 to 9.

<Characteristics evaluation test 1: Pot life>
The solution A and the solution B of the samples 1-9 were mixed, and the liquid mixture was prepared. Discard each mixture obtained approximately, leave the rest at room temperature for 2 hours, visually observe the time-dependent change of the phase state of each mixture visually and determine the time until the mixture solidifies (solidification time) It measured and evaluated based on a predetermined judgment standard, and the result was shown in the following table 1. The judgment criteria in Table 1 below are “A” for the solidification time of 30 minutes or more, “B” for the solidification time of less than 30 minutes and “C” for the solidification time of 15 minutes or less ". In addition, since the solidification time of samples 6-8 was 20 minutes or more and less than 30 minutes, it was set as "B."

<Characteristics evaluation test 2: Vulcanization characteristics>
The solution A and the solution B of the samples 1-9 were mixed, and the liquid mixture was prepared. Next, the mold temperature of the rheometer was set to 180 ° C., and each mixture of the obtained samples 1 to 9 was poured into the mold. Based on the change in viscosity of each mixture of samples 1 to 9 obtained, the time (vulcanization time) required for each mixture to reach the optimum vulcanization point (t 90) was measured, and evaluated based on a predetermined judgment standard. The results are shown in Table 1 below. The criteria in Table 1 below were "good" when the vulcanization time was within 20 minutes, and "defective" when the vulcanization time exceeded 20 minutes.

<Characteristics evaluation test 3: Storage stability>
Solution A of Samples 7 and 8 was allowed to stand at 80 ° C. for 2 hours, and the appearance of each solution A after 2 hours was visually observed and evaluated based on a predetermined judgment standard. The results are shown in Table 1 below. . The criteria in Table 1 below were "good" when the appearance was transparent and "poor" when it was cloudy.

<Characteristics evaluation test 4: Solubility>
With respect to the solutions A and B of the samples 3 and 9, the undissolved matter in the solutions was visually observed and evaluated based on a predetermined judgment standard. The results are shown in Table 1 below. The criteria in Table 1 below were "good" when there was no residue in the two solutions and "bad" when there was a residue.

<Discussion>
Sample 4 was compared with Samples 5 and 6 in Test 1 above. Here, FIG. 2 is a graph showing the relationship between the vulcanization time and the solidification time of each sample. As shown in Table 1 and FIG. 2 above, when the blocking agent was added to either solution A or solution B as in samples 5 and 6, the solidification time was extended as compared with sample 4.

  Further, in the above-mentioned test 1, samples 7 and 8 were compared. As shown in Table 1 and FIG. 2 above, adding a positive catalyst to solution A as in sample 8 shortens the solidification time more than sample 7, and adding a positive catalyst to solution B as in sample 7 Also the solidification time was extended. This is considered to be caused by the addition of the positive catalyst to the solution B, the activity of the isocyanate group of the polyisocyanate is increased, and the side reaction (isocyanate dimerization) progresses and the deactivation by water (urea formation) takes place.

  Samples 1 and 7 to 9 were compared in the above tests 1 and 2. As shown in Table 1 and FIG. 2 above, when a positive catalyst is added to solution B and a negative catalyst is added as in sample 1, the setting time is extended compared to samples 7 to 9, and the vulcanization time is kept good. It was done.

  This is because when the two liquids are mixed (at room temperature to 80 ° C.), that is, during the uncured reaction, a complex is formed by the positive catalyst and the negative catalyst, so the catalytic ability of the positive catalyst is limited and the progress of the urethanization reaction is The suppression is considered to prolong the solidification time of Sample 1 more than Samples 7-9. In addition, at the time of mold injection (180 ° C.), that is, at the time of curing reaction, the complex formed by the positive catalyst and the negative catalyst is thermally dissociated and the positive catalyst exhibits catalytic ability, and the vulcanization time is maintained good. It is thought that.

  Samples 1 and 2 were compared with Samples 5 to 9 in Tests 1 and 2 above. As shown in the above Table 1 and FIG. 2, when the blocking agent is added to either solution A or solution B as in samples 1 and 2, and the positive catalyst and the negative catalyst are added to solution B, samples 5 to 9 are obtained. While the setting time was further extended to 30 minutes or more, the curing time was shortened to 20 minutes or less, and the curing characteristics were improved.

  That is, in addition to the combined use of the positive catalyst and the negative catalyst, samples 1 and 2 have the solidification time extended to 30 minutes or more than samples 5 to 9 and the vulcanization time is 20 minutes or less by addition of the blocking agent. It is considered that the shortened state is maintained, and the prolongation of the solidification time and the shortening of the vulcanization time can be compatible.

  In Test 3 above, samples 7 and 8 were compared. As shown in Table 1 above, the addition of the positive catalyst to the solution A confirmed that the solution A of the sample 8 had cloudiness. It is considered that this is because the activity of the isocyanate group is increased, and a side reaction by urea dimerization due to isocyanate dimerization or moisture absorption proceeds. On the other hand, Sample 7 remained transparent even if a positive catalyst was added to solution B, and there was no particular problem. Therefore, it was confirmed that it is better to add the positive catalyst to solution B from the viewpoint of side reaction suppression.

  In Test 4 above, sample 3 and sample 9 were compared. As shown in Table 1 above, it was confirmed that the negative catalyst was not soluble in solution A as in sample 9, but was soluble in solution B as in sample 3.

<Summary>
It turned out that there is no functional problem when the blocking agent is added to either solution A or solution B. In any case, the solidification time can be extended more than when the blocking agent is not added, and the pot life can be improved.

  Moreover, it became clear that it is necessary to add a positive catalyst and a negative catalyst to B liquid while using a positive catalyst and a negative catalyst together. As a result, the pot life is improved by prolonging the solidification time and the vulcanization characteristics are improved by shortening the vulcanization time, as compared with the case where the catalysts are not used in combination and not added to the solution B, and the pot life and pot life It is possible to simultaneously improve the vulcanization characteristics.

  The cleaning blade produced using the polyurethane elastomer composition according to the present invention is suitable for use in cleaning blades used in electrophotographic copying machines and printers, or image forming apparatuses such as toner jet copying machines and printers. However, it can also be used in other applications. Other applications include, for example, various blades and cleaning rolls.

1 cleaning blade 10 blade main body 11 elastic body 12 surface treatment layer 20 support member

Claims (9)

  A polyurethane elastomer composition comprising a cast-type polyurethane elastomer for use in a cleaning blade, comprising: a bifunctional polyol, a polyisocyanate, a curing agent, and a positive catalyst which is an imidazole compound that promotes a urethanization reaction, A polyurethane elastomer composition comprising: a negative catalyst which is a carboxylic acid compound which limits the catalytic ability of the positive catalyst according to temperature; and a blocking agent which protects the isocyanate group of the polyisocyanate. A mixed liquid of a first liquid containing the bifunctional polyol and the polyisocyanate, and a second liquid containing the curing agent and the negative catalyst,
The positive catalyst is contained in at least one of the first liquid and the second liquid,
The polyurethane elastomer composition according to claim 1, wherein the blocking agent is contained in at least one of the first liquid and the second liquid.   The polyurethane elastomer composition according to claim 2, wherein the positive catalyst is contained in the second liquid.   The polyurethane elastomer composition according to any one of claims 1 to 3, comprising a urethane prepolymer obtained by prepolymerizing at least a part of the bifunctional polyol and the polyisocyanate. A method for producing a cleaning blade using a castable type polyurethane elastomer obtained from a polyurethane elastomer composition, comprising:
A bifunctional polyol, a polyisocyanate, a curing agent, a positive catalyst which is an imidazole compound which accelerates a urethanation reaction, a negative catalyst which is a carboxylic acid compound which restricts the catalytic ability of the positive catalyst according to temperature, and the polyisocyanate Preparing a polyurethane elastomer composition which is a mixed liquid by mixing a blocking agent for protecting an isocyanate group;
Forming a cleaning blade from a polyurethane elastomer which is a cured product obtained by curing the mixed liquid by casting, and a forming step of the cleaning blade. The preparation process is
A first preparation step of preparing a first liquid containing the bifunctional polyol and the polyisocyanate, and optionally containing at least one of the positive catalyst and the blocking agent;
Preparing a second liquid containing the curing agent and the negative catalyst, optionally including at least one of the positive catalyst and the blocking agent;
6. A cleaning method according to claim 5, comprising: a third preparation step of preparing the polyurethane elastomer composition which is the mixed solution by mixing the first solution and the second solution. How to make a blade.   The method according to claim 6, wherein the second preparation step includes preparing the second liquid containing the positive catalyst.   The method for producing a cleaning blade according to any one of claims 5 to 7, comprising a urethane prepolymer obtained by prepolymerizing at least a part of the bifunctional polyol and the polyisocyanate.   A cleaning blade characterized in that it is a molded article of a cured product of the polyurethane elastomer composition according to any one of claims 1 to 4.

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