JPWO2019058909A1 - Polyurethane elastomer composition, method for producing cleaning blade and cleaning blade - Google Patents

Abstract

The present invention provides a polyurethane elastomer composition, a method for producing a cleaning blade, and a cleaning blade capable of maintaining the material properties required for a cleaning blade and at the same time improving both pot life and vulcanization properties. A polyurethane elastomer composition used for a cleaning blade comprising a cast type polyurethane elastomer, which is a bifunctional polyol, a polyisocyanate, a curing agent, and an imidazole compound that accelerates a urethanization reaction. It contains a positive catalyst, a negative catalyst that is a carboxylic acid compound that limits the catalytic ability of the positive catalyst depending on the temperature, and a blocking agent that protects the isocyanate group of the polyisocyanate. [Selection figure] None

Description

  The present invention relates to a polyurethane elastomer composition, a method for producing a cleaning blade, and a cleaning blade.

  In general, in an electrophotographic process, at least cleaning, charging, exposure, development, and transfer processes are performed on an electrophotographic photosensitive member. In each process, a cleaning blade that removes and cleans toner remaining on the surface of the photosensitive drum, a conductive roll that imparts uniform charge to the photosensitive member, a transfer belt that transfers a toner image, and the like are used. The cleaning blade is manufactured mainly from a thermosetting polyurethane resin from the viewpoints of plastic deformation and wear resistance.

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

  For example, when a cleaning blade is manufactured using a prepolymer method, a mold (mold) for the cleaning blade is prepared, and a liquid composition that is a raw material for the polyurethane resin is injected into the mold. Next, the cured product obtained by curing (urethanizing) the liquid composition in the mold is demolded to obtain a cured polyurethane product. Finally, the obtained polyurethane cured product is molded to 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 liquid composition is prepared by adding a curing agent, a catalyst, and other necessary components to the prepolymer. To do.

  In the production of the cleaning blade by the prepolymer method, pot life (solidification time from the mixing of each raw material until the liquid composition is solidified and cannot be injected) and curing time greatly affect the production efficiency. If the curing time is long, a great investment is required due to an increase in the number of molds. For this reason, various studies have been made on methods for shortening the curing time (for example, Japanese Patent No. 4585360 (Patent Document 1), Japanese Patent No. 4585360 (Patent Document 2), Japanese Patent Application Laid-Open No. 2007-178773 (Patent Document). 3), see Japanese Patent No. 5492746 (Patent Document 4)).

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

  Further, when it is desired to further shorten the curing time, the reaction rate of the liquid composition increases as the amount of the catalyst increases. Then, due to the increase in the viscosity of the liquid composition, it becomes difficult to inject a required amount of the liquid composition into the mold. Moreover, the problem that the polyurethane waste hardened | cured before the injection | pouring mixes in a liquid composition also arises. In any case, an increase in the catalyst amount may lead to an increase in defective products. In addition, there is a problem that a large product cannot be produced due to an increase in the viscosity of the liquid composition.

  In view of such circumstances, the present invention maintains a material property required for a cleaning blade, and at the same time, can improve both pot life and vulcanization property, a polyurethane elastomer composition, a method for producing a cleaning blade, and An object is to provide a cleaning blade.

  A first aspect of the present invention that solves the above problems is a polyurethane elastomer composition used for a cleaning blade, which is made of a cast type polyurethane elastomer, and includes a bifunctional polyol, a polyisocyanate, a curing agent, and a urethane. A positive catalyst that is an imidazole compound that promotes the conversion reaction, a negative catalyst that is a carboxylic acid compound that limits the catalytic ability of the positive catalyst according to temperature, and a blocking agent that 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 accelerates a bifunctional polyol, polyisocyanate, curing agent, and 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 depending on temperature, and a blocking agent which protects the isocyanate group of the polyisocyanate A method for producing a cleaning blade, comprising: a preparation step for preparing an elastomer composition; and a molding step for molding a cleaning blade from a polyurethane elastomer which is a cured product obtained by curing the mixed solution by casting. It is.

  Yet another aspect of the present invention is a cleaning blade, which is a molded article of a cured product of the polyurethane elastomer composition of the embodiment of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, while maintaining the material characteristic requested | required of a cleaning blade, the polyurethane elastomer composition, the manufacturing method of a cleaning blade, and a cleaning blade which can make a pot life and a vulcanization | cure characteristic improved simultaneously are provided. be able to.

It is sectional drawing which shows an example of the cleaning blade which concerns on embodiment of this invention. It is the graph which showed the relationship between the vulcanization time and the solidification time of each sample.

  Below, the polyurethane elastomer composition which concerns on embodiment of this invention is demonstrated in detail. In this embodiment, the case where the polyurethane elastomer composition is used for the cleaning blade of the image forming apparatus will be described as an example. However, the 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 illustrating 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 body (also referred to as a cleaning blade itself) 10 and a support member 20, and the blade body 10 and the support member 20 are connected via an adhesive (not shown). It is joined. The blade body 10 is composed of an elastic body 11 that is a molded body of a rubber base material (polyurethane).

  The elastic body 11 constituting the blade body 10 is made of a cast type polyurethane elastomer. The polyurethane elastomer is a cured product of the polyurethane elastomer composition. The cast type polyurethane elastomer is a polyurethane elastomer obtained by processing a polyurethane elastomer composition by a cast molding method. A polyurethane elastomer is molded into an elastic body 11 (molded body) constituting the blade body 10. Such polyurethane elastomer compositions contain bifunctional polyols, polyisocyanates, curing agents, positive catalysts, negative catalysts, blocking agents, and other necessary ingredients.

  The bifunctional polyol applicable in the present embodiment is a long-chain polyol, and examples thereof include polyester polyol, polycarbonate polyol obtained by reaction of diol and alkyl carbonate, caprolactone-based polyol, 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), naphthylene diisocyanate (NDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HDI) ), Paraphenylene diisocyanate (PPDI), lysine diisocyanate methyl ester (LDI), dimethyl diisocyanate (DDI), and the like. Multimers and denatured bodies may be used. Moreover, these polyisocyanates may be used independently and may use 2 or more types together. Among these, it is preferable to use MDI or TODI from the viewpoints of strength and wear resistance.

  In this embodiment, a urethane prepolymer in which at least a part of a bifunctional polyol and a polyisocyanate is prepolymerized may be used. Here, the urethane prepolymer is an unvulcanized compound in which the urethanization reaction between the bifunctional polyol and the polyisocyanate proceeds to a certain extent, and these are partially polymerized (urethane bonds are formed). The terminal of the urethane prepolymer is an isocyanate group (—N═C═O), and this terminal group (NCO terminal) reacts with a curing agent (forms a urethane bond) to form a polyurethane elastomer. Bifunctional polyol and polyisocyanate can stabilize the quality of the polyurethane elastomer composition by using a urethane prepolymer in which the urethanization reaction has been advanced to some extent in advance. As a result, a high-quality cleaning blade 1 can be manufactured using such a polyurethane elastomer composition.

  When such a urethane prepolymer is used, the polyurethane elastomer composition is prepared so as to contain other bifunctional polyols and polyisocyanates as necessary together with a predetermined urethane prepolymer. Therefore, in this specification, “the polyurethane elastomer composition contains a bifunctional polyol and a polyisocyanate” is a concept including a 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 has a low molecular weight polyol (short chain polyol) having a number average molecular weight of 500 or less, and bifunctional polyols, polyhydric alcohols, and the like can be used. These curing agents may be used alone or in combination of two or more.

  Examples of the bifunctional low molecular weight polyol 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 those having a molecular weight of 200 or less because a cured product of a polyurethane elastomer composition having a high hardness can be produced.

  Examples of polyhydric alcohols include trifunctional fats such as glycerin, 1,2,4-butanetriol, trimethylolethane (TME), 1,1,1-trimethylolpropane (TMP), and 1,2,6-hexanetriol. Polyol triol in which ethylene oxide, butylene oxide or the like is added to trifunctional aliphatic polyol; Polyester triol in which lactone or the like is added to trifunctional aliphatic polyol; Tetrafunctional aliphatic polyol such as diglycerin (diglycerol) 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 to obtain a highly crosslinked elastic body 11 having a three-dimensional network structure.

  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 more preferable to use together.

  The positive catalyst promotes the urethanization reaction. If it is such a catalyst, it will not specifically limit, For example, a tertiary amine catalyst can be mentioned. Specifically, amino alcohols such as dimethylethanolamine; trialkylamines such as triethylamine; tetraalkyldiamines such as N, N, N ′, N′-tetramethyl-1,3-butanediamine; TEDA, piperazine series, Triazine-based and imidazole-based compounds 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. Of these, 2-ethyl-4-methylimidazole is preferred.

  The negative catalyst is capable of limiting the catalytic ability 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 (urethanization reaction), that is, during the uncured reaction (for example, at room temperature), a salt (complex) is formed between the negative catalyst and the positive catalyst. ) To limit the catalytic ability of the positive catalyst and suppress 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, that is, at the time of the curing reaction (for example, at a high temperature of 120 ° C. to 200 ° C.), the complex dissociates due to heat and the positive catalyst has catalytic ability. Promotes the urethanization reaction. That is, the negative catalyst imparts temperature sensitivity that suppresses or promotes the urethanization 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 the mixing of each raw material until the polyurethane elastomer composition is solidified and cannot be injected) can be extended. Moreover, 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 improve both 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 depending on the temperature as described above. For example, a carboxylic acid compound such as hydroxy acid can be used. These negative catalysts may be used independently and may use 2 or more types together.

  Hydroxy acids include glycolic acid, lactic acid, tartronic 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 citramalic acid, citric acid, isocitric acid, leucine acid, mevalonic acid, pantoic acid, ricinoleic acid, ricinaleic acid, cerebronic acid, quinic acid, shikimic acid; salicylic acid, creosotenic acid (homosalicylic acid, hydroxy ( Methyl) benzoic acid), monohydroxybenzoic acid derivatives such as vanillic acid, silling acid; dihydroxybenzoic acid derivatives such as pyrocatechuic acid, resorcylic acid, protocatechuic acid, gentisic acid, and orthoric acid; trihydroxybenzoic acid derivatives such as gallic acid; Mandelic acid, benzylic acid, ato 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. Of these, tartaric acid (2,3-dihydroxybutanedioic acid) is preferable.

  The blocking agent can protect (block) the isocyanate group of the polyisocyanate and limit the progress of the urethanization reaction. By using such a blocking agent, when the liquid temperature of the polyurethane elastomer composition is lower than the initiation temperature of the curing reaction (urethanization reaction), the isocyanate group is protected and the urethanization reaction can be suppressed. As a result, 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.

  Examples of blocking agents include 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 and methyl ethyl ketone Oximes such as oxime, methyl isobutyl ketone oxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime; 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 may contain an organic solvent as necessary. The organic solvent is not particularly limited as long as it dissolves each component of the polyurethane elastomer composition, but an organic solvent having no active hydrogen capable of reacting with polyisocyanate is preferably used. Examples of such an organic solvent include methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF), acetone, ethyl acetate, butyl acetate, toluene, xylene and the like. In these, methyl ethyl ketone (MEK), acetone, and ethyl acetate are preferable.

  The polyurethane elastomer composition may contain other components as necessary. Examples of other components include hydrolysis inhibitors and antiaging agents.

  The blending ratio of each component in the polyurethane elastomer composition can be appropriately designed according to the material characteristics required for the cleaning blade 1 (blade body 10). In view of the function of the cleaning blade, the hardness (JIS A) of the polyurethane elastomer composition is preferably adjusted to 60-80.

  The polyurethane elastomer composition is a mixed solution prepared by the above-described blending, but may be obtained by mixing two separately prepared solutions. In this case, the mixed liquid (polyurethane elastomer composition) includes a first liquid (also referred to as liquid A) containing a bifunctional polyol and 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 mixed liquid (polyurethane elastomer composition) obtained by any method can be cured to form a cured product (polyurethane elastomer), and then molded to produce the blade body 10 of the cleaning blade 1. At least a part of the bifunctional polyol and polyisocyanate may be a urethane prepolymer.

  The positive catalyst only needs to be contained in one of the first liquid and the second liquid, and is particularly preferably contained in the second liquid. This is because when only the positive catalyst is added to the first liquid, the activity of the isocyanate group (—N═C═O) of the polyisocyanate increases, the side reaction (isocyanate dimerization) proceeds, and the deactivation due to moisture (urea) This is because the storage stability of the first liquid deteriorates.

  Therefore, from the viewpoint of suppressing the progress of side reactions and urea formation, the negative catalyst is preferably contained in the second liquid containing the positive catalyst. Further, when tartaric acid is used as the negative catalyst, for example, tartaric acid having a high melting point is difficult to dissolve in the first liquid, and the liquid temperature of the polyurethane elastomer composition is urethanized when the first liquid and the second liquid are mixed. When the temperature is lower than the reaction start temperature, it becomes difficult to limit the catalytic ability of the positive catalyst.

  Moreover, the addition method of the blocking agent is not limited as long as the liquid temperature of the polyurethane elastomer composition is lower than the initiation temperature of the curing reaction (urethanization reaction) as long as the progress of the urethanization reaction can be restricted. That is, the blocking agent only needs to be contained in one of the first liquid and the second liquid, and may be contained in both the first liquid and the second liquid as necessary. Or it is good also as a liquid mixture by adding the block agent prepared separately at the time of mixing of a 1st liquid and a 2nd liquid.

  The elastic body 11 may have a surface treatment layer 12 having a predetermined thickness t on the surface layer portion. The surface treatment layer 12 can be formed, for example, by impregnating the surface treatment portion into the surface layer portion of the elastic body 11 and curing it. The surface treatment layer 12 is a cured product containing polyisocyanate contained in the surface treatment liquid, and can be one that has reacted with the polyol component of the elastic body 11. For example, the surface treatment layer 12 may be formed at least on a portion of the elastic body 11 that comes into contact with the cleaning target.

  The surface treatment liquid used for forming 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. The surface treatment liquid may contain other components as necessary.

  Even if it is thin, the surface treatment layer 12 formed using such a surface treatment liquid has high hardness and low friction, and is excellent in anti-caking property, suppression of filming, and cleaning properties. The surface treatment liquid is appropriately selected in consideration of wettability to the elastic body 11, the degree of immersion, and the effective period of the surface treatment liquid.

(Manufacturing method of cleaning blade)
The manufacturing method of the cleaning blade 1 according to the embodiment of the present invention uses a casting type polyurethane elastomer obtained from the polyurethane elastomer composition described above. Here, the manufacturing method of the cleaning blade is not particularly limited. 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 to obtain a mixed liquid. A polyurethane elastomer composition that may be a one-component curable type (hereinafter referred to as “first production method”) using an elastomer composition, or a two-component solution containing each component and then mixed to form a mixed solution A two-component curable type (hereinafter referred to as “second manufacturing method”) may be used.

  For example, the first production method includes a preparation step of 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, and the prepared mixing. A molding step of molding a cleaning blade from a polyurethane elastomer, which is a cured product obtained by curing the liquid by casting.

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

  In the first manufacturing method and the second manufacturing method, a prepolymer method is used, and the prepared mixed solution is mixed by an injector, and then compressed and injected into a mold (molding die). An integrally-molded injection machine that can be integrally formed with the support member 20), which is a holder, may be applied, but is not limited thereto. For example, in addition to the prepolymer method, a semi-one-shot method, a one-shot method, or the like may be used, or the blade body 10 and the support member 20 obtained by the molding process may be integrated using another device. You may go.

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

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

  The polyurethane elastomer composition of the present invention contains 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 depending on the temperature, and an isocyanate depending on the temperature. Since the blocking agent capable of protecting the group is contained, the material properties required for the cleaning blade can be maintained, and the pot life and the vulcanization properties can be improved at the same time.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited.

(Sample 1)
In Table 1 below, ester polyols (Polylite CT-4117, manufactured by DIC Corporation) as bifunctional polyols and 4,4′-diphenylmethane diisocyanate (Cosmonate PH, manufactured by Mitsui Chemicals, Inc.) as polyisocyanates are shown. The mixture was mixed and reacted at the indicated blending ratio. Thereafter, the temperature was adjusted to 80 ° C. to obtain a liquid mixture (liquid A) of an NCO-terminated prepolymer and polyisocyanate.

  As curing agents, 1,4-butanediol (Mitsubishi Chemical Co., Ltd., 1,4 Butanediol), 1,1,1-trimethylolpropane (Guangei Chemical Industry Co., Ltd., Trimethylolpropane) and diglycerol (Sakamoto Pharmaceutical Co., Ltd.) Co., Ltd., diglycerin S), 2,4-pentanedione (Tokyo Chemical Industry Co., Ltd., acetylacetone) as a blocking agent, 2-ethyl-4-methylimidazole (manufactured by Mitsubishi Chemical Corporation, jER) as a positive catalyst Cure (registered trademark) EMI24) was added at the blending ratio shown in Table 1 below and dissolved at 80 ° C., and then 2,3-dihydroxybutanedioic acid (manufactured by Wako Pure Chemical Industries, Ltd.) Tartaric acid) was added at the blending ratio shown in Table 1 below and stirred until dissolved. Then, it cooled naturally to room temperature and obtained the liquid mixture (B liquid).

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

(Samples 2-9)
The liquid A and the liquid B were prepared in the same manner as the sample 1 except that the liquid mixture was prepared at the blending ratio shown in Table 1 below.

<Characteristic evaluation test 1: Pot life>
Liquids A and B of Samples 1 to 9 were mixed to prepare a mixed liquid. Discard each obtained mixture roughly, leave the residue at room temperature for 2 hours, visually observe the time-dependent change of the phase state of each mixture and set the time (solidification time) until the mixture solidifies. Measurements were made and evaluated based on predetermined criteria, and the results are shown in Table 1 below. The criteria in Table 1 below are “A” when the solidification time is 30 minutes or more, “B” when the solidification time is more than 15 minutes and less than 30 minutes, and “C” when the solidification time is 15 minutes or less. " In addition, since the solidification time of Samples 6 to 8 was 20 minutes or more and less than 30 minutes, it was set as “B”.

<Characteristic evaluation test 2: Vulcanization characteristics>
Liquids A and B of Samples 1 to 9 were mixed to prepare a mixed liquid. Next, the mold temperature of the rheometer was set to 180 ° C., and the obtained mixed solutions of Samples 1 to 9 were injected into the mold. The time (vulcanization time) required for each liquid mixture to reach the optimum vulcanization point (t90) is measured by the change in viscosity of each liquid mixture of Samples 1 to 9 obtained and evaluated based on a predetermined criterion. The results are shown in Table 1 below. In addition, the judgment criteria in the following Table 1 set “good” when the vulcanization time was within 20 minutes, and “bad” when the vulcanization time exceeded 20 minutes.

<Characteristic evaluation test 3: Storage stability>
The liquid A of samples 7 and 8 was allowed to stand at 80 ° C. for 2 hours, and the appearance of each liquid A after 2 hours was visually observed and evaluated based on predetermined criteria. The results are shown in Table 1 below. . In addition, the judgment criteria in the following Table 1 were defined as “good” when the appearance was transparent and “bad” when clouded.

<Characteristic evaluation test 4: solubility>
About the A liquid and B liquid of the samples 3 and 9, the undissolved residue in both liquids was observed visually, and it evaluated based on the predetermined criteria, and the result was shown in following Table 1. The criteria in Table 1 below were defined as “good” when there was no undissolved residue in both solutions, and “bad” when there was undissolved residue.

<Discussion>
In Test 1 above, Sample 4 was compared with Samples 5 and 6. 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, when the blocking agent was added to either the liquid A or the liquid B as in the samples 5 and 6, the solidification time was extended as compared with the sample 4.

  In Test 1 above, Sample 7 and Sample 8 were compared. As shown in Table 1 and FIG. 2, when the positive catalyst is added to the liquid A as in the sample 8, the solidification time is shortened compared to the sample 7, and when the positive catalyst is added to the liquid B as in the sample 7, the sample is compared with the sample 8. Also the solidification time was extended. This is thought to be due to the increase of the activity of the isocyanate group of the polyisocyanate due to the addition of the positive catalyst to the B liquid, and the progress of side reaction (isocyanate dimerization) and the deactivation due to moisture (ureaization).

  In the above tests 1 and 2, sample 1 and samples 7 to 9 were compared. As shown in Table 1 and FIG. 2 above, when a negative catalyst is added to the B liquid in addition to the positive catalyst as in Sample 1, the solidification time is longer than that of Samples 7 to 9, and the vulcanization time remains good. It was done.

  This is because a complex is formed by a positive catalyst and a negative catalyst at the time of mixing two liquids (at room temperature to 80 ° C.), that is, at the time of an uncured reaction. It is thought that the solidification time of sample 1 is extended more than samples 7-9 by being suppressed. 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 dissociated by heat, and the positive catalyst exerts its catalytic ability, so that the vulcanization time is kept good. It is thought.

  In Tests 1 and 2, Samples 1 and 2 were compared with Samples 5 to 9. As shown in Table 1 and FIG. 2 above, when a blocking agent is added to either liquid A or liquid B as in samples 1 and 2, and a positive catalyst and a negative catalyst are added to liquid B, samples 5 to 9 In addition, the solidification time was extended to 30 minutes or more, and the vulcanization time was shortened to 20 minutes or less to improve the vulcanization characteristics.

  In other words, in Samples 1 and 2, the solidification time is extended to 30 minutes or more and the vulcanization time is 20 minutes or less as compared with Samples 5 to 9 by adding a blocking agent in addition to the combined use of a positive catalyst and a negative catalyst. It is considered that the shortened state is maintained, and that the solidification time can be extended and the vulcanization time can be shortened.

  In Test 3 above, Sample 7 and Sample 8 were compared. As shown in Table 1 above, white turbidity was confirmed in the liquid A of the sample 8 by the addition of the positive catalyst to the liquid A. This is presumably because the activity of the isocyanate group is increased and a side reaction due to the dimerization of the isocyanate or the urea formation by moisture absorption proceeds. On the other hand, Sample 7 maintained a transparent state even when a positive catalyst was added to Liquid B, and there was no particular problem. Therefore, it was confirmed that the positive catalyst should be added to the B liquid from the viewpoint of suppressing side reactions.

  In the test 4, the sample 3 and the sample 9 were compared. As shown in Table 1 above, it was confirmed that the negative catalyst did not dissolve in the liquid A as in the sample 9, but dissolved in the liquid B as in the sample 3.

<Summary>
It became clear that there was no functional problem when the blocking agent was added to either the liquid A or the liquid B. In any case, the solidification time can be extended more than when no blocking agent is added, and the pot life can be improved.

  Moreover, it became clear that it is necessary to add the positive catalyst and the negative catalyst to the liquid B together with the positive catalyst and the negative catalyst. Thereby, compared with the case where each catalyst is not used in combination and not added to the liquid B, the pot life is improved by extending the solidification time, and the vulcanization characteristics are improved by shortening the vulcanization time. It is possible to simultaneously improve the vulcanization characteristics.

  The cleaning blade manufactured using the polyurethane elastomer composition according to the present invention is suitable for a cleaning blade used in an image forming apparatus such as an electrophotographic copying machine and printer, or a toner jet copying machine and printer. However, it can be used for other purposes. Examples of other applications include various blades and cleaning rolls.

DESCRIPTION OF SYMBOLS 1 Cleaning blade 10 Blade main body 11 Elastic body 12 Surface treatment layer 20 Support member

Claims (9)

  A polyurethane elastomer composition used for a cleaning blade, comprising a cast type polyurethane elastomer, a bifunctional polyol, a polyisocyanate, a curing agent, and a positive catalyst that is an imidazole compound that promotes a urethanization reaction, A polyurethane elastomer composition comprising: a negative catalyst that is a carboxylic acid compound that limits the catalytic ability of the positive catalyst according to temperature; and a blocking agent that protects an 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 cast type polyurethane elastomer obtained from a polyurethane elastomer composition,
A bifunctional polyol, a polyisocyanate, a curing agent, a positive catalyst that is an imidazole compound that promotes a urethanization reaction, a negative catalyst that is a carboxylic acid compound that limits the catalytic ability of the positive catalyst according to temperature, and the polyisocyanate. A preparation step of preparing a polyurethane elastomer composition which is a mixed liquid by mixing a blocking agent for protecting an isocyanate group;
And a molding step of molding a cleaning blade from a polyurethane elastomer which is a cured product obtained by curing the mixed solution by casting. The preparation step includes
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;
A second preparation step of preparing a second liquid containing the curing agent and the negative catalyst, and optionally containing at least one of the positive catalyst and the blocking agent;
The cleaning according to claim 5, further comprising: a third preparation step of preparing the polyurethane elastomer composition that is the mixed liquid by mixing the first liquid and the second liquid. Blade manufacturing method.   The method for manufacturing a cleaning blade according to claim 6, wherein in the second preparation step, the second liquid containing the positive catalyst is prepared.   The method for manufacturing a cleaning blade according to any one of claims 5 to 7, further comprising a urethane prepolymer obtained by prepolymerizing at least a part of the bifunctional polyol and the polyisocyanate.   A cleaning blade, which is a molded product of a cured product of the polyurethane elastomer composition according to any one of claims 1 to 4.

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