JP2015137316A - Polyurethane elastomer-forming composition for elastic member for roll, and elastic member for roll using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane elastomer-forming composition for an elastic member for a roll, which has excellent elastic recovery, workability such as pot-life and, furthermore, mechanical properties, and to provide an elastic member for a roll using the same.SOLUTION: An elastic member having excellent workability such as pot-life, elastic recovery, and mechanical properties can be obtained by using 2,4'-diphenylmethane diisocyanate and a hexamethylene diisocyanate-modified polyisocyanate in combination as a polyisocyanate component of a polyurethane elastomer-forming composition for an elastic member for a roll.

Description

The present invention relates to a polyurethane elastomer-forming composition for roll elastic members useful for paper feed rolls, industrial rolls and roller members of electronic and electrical equipment such as copying machines, printers, facsimiles, etc., and roll elastic members using the compositions About.

Roll members used in various fields such as the paper industry and printing industry, and elastic molded products such as tires and belts, etc. have mechanical strength (tensile strength, elongation), water resistance, compression resistance, and low resilience. Such performance is required. Conventionally, nitrile butadiene rubber (NBR), chloroprene rubber (CR), ethylene propylene diene monomer (EPDM), silicone resin, and polyurethane elastomer have been used for the above-mentioned applications, and in particular, polyurethane elastomer is compared with other resins. Thus, it is preferably used since it has excellent mechanical strength and wear resistance, is easy to process, and the hardness of the elastic molded body can be adjusted to a wide range of 20 to 100 in terms of JIS-A hardness.

In recent years, there is an increasing demand for roll members that are used in severe conditions such as high-speed printing, continuous production, maintenance-free, and the like for roll members used in the paper manufacturing industry, the printing industry, and the like.
In such a background, an NCO group-terminated urethane prepolymer composed of diphenylmethane diisocyanate and polycarbonate diol, a diol having a number average molecular weight of 50 to 150, a polyether polyol having a number average molecular weight of 600 to 2000, and a number average molecular weight of 200 to 400 A two-component thermosetting polyurethane elastomer composition excellent in compression set and rebound resilience using a glycerin-modified propylene oxide adduct as a curing agent has been proposed (for example, see Patent Document 1).
Further, as a polyurethane elastomer-forming composition for casting excellent in reactivity (coexistence of curability and pot life), compression set, rebound resilience, mechanical strength and heat resistance, trimethylolpropane and 3-methyl-1 Polyurethane elastomer-forming composition for casting in which a polyester polyol composed of 1,5-pentanediol and adipic acid and having a molecular weight of 500 to 2500 is used, and the crosslinking density is adjusted to 0.11 to 0.16 mmol / g, or modified with hexamethylene diisocyanate Urethane elastomer-forming composition having a JIS-A hardness of 20 to 60 and a diphenylmethane diisocyanate having a high content of 2,4'-diphenylmethane diisocyanate and a curing agent having a high content of 2,4'-diphenylmethane diisocyanate As an aromatic diamine Type polyurethane elastomer has been proposed (e.g., refer to Patent Document 5 JP 2).

JP2013-163778A JP 2008-222750 A JP 2004-256679 A JP-A-10-237153 JP 2008-133343 A

However, roll members obtained from conventional polyurethane elastomers were excellent in rebound resilience and compression set as improvement of long-term durability, but insufficient in terms of elastic recovery against vibration caused by high-speed printing. This may cause problems such as printing misalignment and fouling.

The present invention has been made based on the above circumstances, and 2,4′-diphenylmethane diisocyanate and hexamethylene diisocyanate modified polyisocyanate are added to the polyisocyanate component of the polyurethane elastomer-forming composition for roll elastic members. By using together, it is providing the roll elastic member excellent in workability, such as a pot life, and excellent in elastic recovery property and mechanical physical property.

The present invention is shown in the following (1) and (2).
(1) The polyurethane elastomer-forming composition for roll elastic members comprises at least a polyisocyanate (A) and a polyol (B), and the polyisocyanate (A) is 2,4′-diphenylmethane diisocyanate (A1), Containing a hexamethylene diisocyanate modified polyisocyanate (A2) having an average number of functional groups of 3 to 7, and the total amount of 2,4′-diphenylmethane diisocyanate (A1) and hexamethylene diisocyanate modified polyisocyanate (A2), It is at least 60% by mass or more based on the polyisocyanate (A), the mass ratio of (A1) to (A2) is (A1) / (A2) = 30/70 to 75/25, and hexamethylene Diisocyanate modified polyisocyanate (A2) is an allophanate modified Characterized in that it is a polyisocyanate (A2-1), and / or isocyanurate-modified polyisocyanates (A2-2).
(2) The roll elastic member obtained by thermosetting the polyurethane elastomer-forming composition for roll elastic member according to (1) has a JIS-A hardness in the range of 20 to 70.

By using the polyurethane elastomer-forming composition for roll elastic members of the present invention for roll elastic members, roll elasticity excellent in workability such as pot life that could not be achieved conventionally, and excellent in elastic recovery and mechanical properties. A member can be obtained.

The polyurethane elastomer-forming composition for roll elastic members of the present invention is obtained by reacting at least a polyisocyanate (A) and a polyol (B), and the polyisocyanate (A) is 2,4'-diphenylmethane diisocyanate. (A1), hexamethylene diisocyanate modified polyisocyanate (A2) having an average functional group number of 3 to 7, and 2,4′-diphenylmethane diisocyanate (A1), hexamethylene diisocyanate modified polyisocyanate (A2) ) With respect to the polyisocyanate (A), the mass ratio of (A1) to (A2) is (A1) / (A2) = 30/70 to 75/25. It is.
In the polyurethane elastomer-forming composition for roll elastic members, the total amount of 2,4′-diphenylmethane diisocyanate (A1) and hexamethylene diisocyanate-modified polyisocyanate (A2) having an average functional group number of 3 to 7 is changed to polyisocyanate ( With respect to A), at least 60% by mass or more, and the mass ratio of (A1) and (A2) is in the range of (A1) / (A2) = 30/70 to 75/25, Both elastic recoverability can be achieved.
If the mass ratio of 2,4′-diphenylmethane diisocyanate (A1) is less than the lower limit, the pot life may be reduced, and if it exceeds the upper limit, the elastic recovery property may be reduced.
Further, when the mass ratio of the hexamethylene diisocyanate-modified polyisocyanate (A2) is less than the lower limit value, there is a fear that the elastic recovery property is lowered. When the upper limit value is exceeded, the mechanical properties of the roll elastic member are lowered. There is a fear.

Next, the hexamethylene diisocyanate-modified polyisocyanate (A2) of the present invention will be described in detail. As the hexamethylene diisocyanate-modified polyisocyanate (A2), an allophanate-modified polyisocyanate (A2-1) and / or isocyanurate-modified polyisocyanate (A2-2) derived from 1,6-hexamethylene diisocyanate is used.

The allophanate-modified polyisocyanate (A2-1) can be obtained by reacting 1,6-hexamethylene diisocyanate with monool and / or polyol in the presence of an allophanate catalyst.
The monool and polyol used in the allophanate-modified polyisocyanate (A2-1) can be used without any particular limitation as long as the number of carbons including the main chain and the side chain is in the range of 1 to 30. it can. When the number of carbon atoms exceeds 30, the compatibility with the polyol (B) is lowered, and there is a possibility that sufficient performance as a roll elastic member may not be exhibited.

<Monoall>
Specific examples of monools used in the allophanate-modified polyisocyanate (A2-1) include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2 -Pentanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 2-nonanol, isononanol, 1-decanol, 1-undecanol, 1-dodecanol, 2-ethyl-1 -Hexanol, 3,3,5-trimethyl-1-hexanol, 1-tridecanol, 2-tridecanol, 1-tetradecanol, 2-octyldodecanol, 1-pentadecanol, 1-hexadecanol, 1-hepta Decanol, 1-octade And 1-nonadecanol, 2-octyldodecanol, behenyl alcohol, 1-hexadecanol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, phenol, cresol, trimethylphenol, etc. Or 2 or more types can be used together.

<Polyol>
Specific examples of the polyol used in the allophanate-modified polyisocyanate (A2-1) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3-butanediol. 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 2-ethyl -1,3-hexanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A Ethylene oxide and propylene oxide adducts Bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, polyester polyol, polyether polyol, polyolefin polyol, polycarbonate polyol, acrylic polyol, silicone polyol, castor oil polyol, and fluorine The polyol which contains at least 2 hydroxyl groups, such as a system polyol, can be mentioned, and can be used alone or in combination of two or more.

Next, the specific manufacturing method of allophanate modified polyisocyanate (A2-1) is demonstrated. Examples of the production method include two production methods: (1) a low-functional type having 3 to 5 functional groups and (2) a high-functional type having 5 to 7 functional groups. In order to obtain an allophanate-modified polyisocyanate having 3 to 7 functional groups according to the present invention, the number of functional groups can be appropriately adjusted and used in combination with a low functional type and a high functional type. In particular, from the viewpoint of elastic recoverability, it is most preferable to use an allophanate-modified polyisocyanate having 3 to 5 functional groups produced by a low functional type.
Moreover, it is preferable that the isocyanate content of the obtained allophanate modified polyisocyanate (A2-1) is in the range of 16 to 21% by mass.

<Method for producing low-functional type allophanate-modified polyisocyanate (A2-1)>
First step: A monool and / or polyol and 1,6-hexamethylene diisocyanate are charged in an excess amount with respect to a hydroxyl group, and in the presence or absence of an organic solvent, 20 Isocyanate group-terminated prepolymer I is produced by urethanization reaction at ~ 100 ° C.
Second step: An isocyanate group-terminated prepolymer I is charged with an allophanatization catalyst, and allophanated at 70 to 150 ° C. until an urethane group is substantially absent by infrared spectroscopic analysis (IR analysis). Terminal prepolymer II is produced. Moreover, in a series of manufacturing processes, reaction is advanced under nitrogen gas or a dry air stream.

Here, “the amount of the isocyanate group is excessive” means that the isocyanate group of the organic diisocyanate is charged so that the molar ratio of the hydroxyl group of the polyol is 6 to 40 in terms of R = isocyanate group / hydroxyl group. It is preferable, and more preferably, charging is performed so that R = 7 to 30. When it is less than the lower limit, allophanate-modified polyisocyanate and isocyanurate-modified polyisocyanate having a molecular weight higher than that of the target product may increase. When the upper limit is exceeded, polyisocyanate containing a urethane group which is a precursor of allophanate-modified polyisocyanate increases, which may lead to a decrease in the number of functional groups and a decrease in productivity and yield.

<Method for producing high-functional type allophanate-modified polyisocyanate>
First step: Monool and / or polyol and 1,6-hexamethylene diisocyanate are charged so that the molar ratio of isocyanate group to hydroxyl group is 2 to 5 in terms of R = isocyanate group / hydroxyl group. The isocyanate group-terminated prepolymer I is produced by urethanization reaction at 20 to 100 ° C. in the presence or absence of a solvent.
Second step: An isocyanate group-terminated prepolymer I is charged with an allophanatization catalyst and is allophanatized at 70 to 150 ° C. until free unreacted organic diisocyanate is 1.0% by mass or less. Polymer II is produced. Moreover, in a series of manufacturing processes, reaction is advanced under nitrogen gas or a dry air stream.

When the reaction is performed in the presence of an organic solvent, various organic solvents that do not affect the reaction can be used.
<Organic solvent>
Specific examples of the organic solvent include aliphatic hydrocarbons such as octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, ketones such as methyl isobutyl ketone and cyclohexanone, esters such as butyl acetate and isobutyl acetate, Ethylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methyl-3-methoxybutyl acetate, glycol ether esters such as ethyl-3-ethoxypropionate, ethers such as dioxane, methylene iodide, monochlorobenzene, etc. And a polar aprotic solvent such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, hexamethylphosphonylamide, and the like. These solvents can be used alone or in combination of two or more.

<First step: step of producing isocyanate group-terminated prepolymer I>
The reaction temperature of the urethanization reaction is 20 to 120 ° C, preferably 50 to 100 ° C. In the urethanization reaction, a known urethanization catalyst can be used. Specifically, organic metal compounds such as dibutyltin diacetate, dibutyltin dilaurate and dioctyltin dilaurate, organic amines such as triethylenediamine and triethylamine, and salts thereof are selected and used. These catalysts can be used alone or in combination of two or more.

The reaction time of the urethanization reaction varies depending on the presence or absence of the catalyst, the type, and the temperature, but is generally within 10 hours, preferably 1 to 5 hours is sufficient.

<Second step: Step of producing isocyanate group-terminated prepolymer II>
When the urethanization reaction is completed, an allophanatization reaction is performed. At this time, the allophanatization reaction may be performed simultaneously with the urethanization reaction or after the urethanization reaction. When the urethanization reaction and the allophanatization reaction are performed simultaneously, the reaction may be performed in the presence of the allophanatization catalyst. When the allophanatization reaction is performed after the urethanization reaction, in the absence of the allophanatization catalyst, After performing the urethanization reaction for a predetermined time, an allophanatization catalyst may be added to carry out the allophanatization reaction.

<Allophanatization catalyst>
As the allophanatization catalyst used in the allophanatization reaction, it can be appropriately selected from known catalysts, and for example, a metal salt of a carboxylic acid can be used.
Specific examples of the carboxylic acid include acetic acid, propionic acid, butyric acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, 2-ethylhexanoic acid and other saturated aliphatic carboxylic acids, cyclohexanecarboxylic acid, Saturated monocyclic carboxylic acids such as cyclopentanecarboxylic acid, saturated polycyclic carboxylic acids such as bicyclo (4.4.0) decane-2-carboxylic acid, mixtures of the above carboxylic acids such as naphthenic acid, oleic acid, linoleic acid , Monocarboxylic acids such as linolenic acid, soybean fatty acid, unsaturated fatty carboxylic acid such as tall oil fatty acid, aromatic aliphatic carboxylic acid such as diphenylacetic acid, aromatic carboxylic acid such as benzoic acid and toluic acid; phthalic acid, Isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid Adipic acid, pimelic acid, suberic acid, kurtaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, and polycarboxylic acids such as β-diethylsuccinic acid, maleic acid, fumaric acid, trimellitic acid, and pyromellitic acid.

In addition, as the metal constituting the metal salt of carboxylic acid, alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium, calcium and barium, other typical metals such as tin and lead, manganese, iron, Examples include transition metals such as cobalt, nickel, copper, zinc, and zirconium.
These carboxylic acid metal salts can be used alone or in combination of two or more. In addition, 0.001-0.1 mass% is preferable with respect to the total mass of monool and / or a polyol, and 1, 6- hexamethylene diisocyanate, and the usage-amount of an allophanatization catalyst is 0.005-0. 03 mass% is more preferable. If it is less than the lower limit, allophanate-modified polyisocyanate is not produced so much, the amount of by-products of urethane-modified polyisocyanate increases, and the average number of functional groups of the resulting polyisocyanate decreases. Moreover, when exceeding an upper limit, there exists a possibility of causing turbidity.

Here, the reaction is performed at an allophanate reaction temperature of 70 to 150 ° C, preferably 90 to 130 ° C. When the reaction temperature is too low, allophanate-modified polyisocyanate is not formed so much, the amount of by-products of urethane-modified polyisocyanate increases, and the average number of functional groups of the resulting polyisocyanate decreases. Moreover, when reaction temperature is too high, the by-product of isocyanurate modification polyisocyanate increases, and there exists a possibility of causing the fall of elastic recoverability.

Further, after the allophanatization reaction, a catalyst poison that deactivates the activity of the catalyst is added to stop the allophanate reaction. The addition timing of the catalyst poison is not particularly limited as long as it is after the allophanatization reaction. However, in order to suppress the progress of the side reaction, it is preferable to add the catalyst poison immediately after the completion of the reaction.

<Catalyst poison>
Specific examples of the catalyst poison used here include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having a sulfonic acid group and a sulfamic acid group, and known compounds such as esters and acyl halides thereof. The These can be used alone or in combination of two or more. Moreover, although the addition amount of a catalyst poison changes with catalyst poisons or the kind of catalyst, it is preferable that it becomes 0.5-10 equivalent of a catalyst, and 0.8-5.0 equivalent is especially preferable. When the catalyst poison is small, the pot life of the allophanate-modified polyisocyanate obtained tends to vary. Moreover, when there is too much catalyst poison, there exists a possibility of producing delay of sclerosis | hardenability.

After completion of the reaction step, a purification step for removing free unreacted organic diisocyanate can be performed. This purification step is mainly used when a low-functional type allophanate-modified polyisocyanate is produced.
<Third step: Purification step>
In the purification step, the free unreacted organic diisocyanate present in the reaction mixture contains, for example, a residue of 1.0% by mass or less by thin film distillation at 120 to 140 ° C. under a high vacuum of 10 to 100 Pa. It is preferable to remove up to the rate. If the upper limit is exceeded, odor and storage stability may be reduced.
Further, when an organic solvent is used in the reaction step, it is removed in this purification step.

The isocyanurate-modified polyisocyanate (A2-2) of the hexamethylene diisocyanate-modified polyisocyanate (A2) used in the present invention includes 1,6-hexamethylene diisocyanate, and the main chain and side chain. It can be obtained by reacting a monool and / or polyol having 1 to 30 carbon atoms with an isocyanurate-forming catalyst.

Next, a specific method for producing isocyanurate-modified polyisocyanate (A2-2) will be described. In addition, it is preferable that the isocyanate content of the isocyanurate modified polyisocyanate (A2-2) manufactured by such a manufacturing method is in the range of 19 to 24% by mass.

<Method for producing isocyanurate-modified polyisocyanate (A2-2)>
First step: A monool and / or polyol and 1,6-hexamethylene diisocyanate are charged in an excess amount with respect to a hydroxyl group, and in the presence or absence of an organic solvent, 20 Isocyanate group-terminated prepolymer I is produced by urethanization reaction at ~ 100 ° C.
Second step: Isocyanurate-forming catalyst is added to isocyanate group-terminated prepolymer I, and isocyanurated at 30 to 70 ° C. until urethane groups are substantially absent by infrared spectroscopic analysis (IR analysis). Isocyanate group-terminated prepolymer II is produced. Moreover, in a series of manufacturing processes, reaction is advanced under nitrogen gas or a dry air stream.
Third step: After adding the catalyst poison to the isocyanate group-terminated prepolymer II, free unreacted organic diisocyanate remains by 1.0% by mass or less by thin-film distillation at 120 to 140 ° C. under a high vacuum of 10 to 100 Pa. Remove to content.

<Isocyanurate catalyst>
Specific examples of the isocyanuration catalyst used in the second step include triethylamine, N-ethylpiperidine, N, N′-dimethylpiperazine, N-ethylmorpholine, tertiary amines such as phenolic Mannich base, tetra Methylammonium bicarbonate, methyltriethylammonium bicarbonate, ethyltrimethylammonium bicarbonate, propyltrimethylammonium bicarbonate, butyltrimethylammonium bicarbonate, pentyltrimethylammonium bicarbonate, hexyltrimethylammonium bicarbonate, heptyltrimethyl Ammonium hydrogen carbonate, octyl trimethyl ammonium hydrogen carbonate, nonyl trimethyl ammonium hydrogen carbonate, decyl trimethyl ammonium hydrogen carbonate, undecyl trimethyl Ammonium bicarbonate, dodecyltrimethylammonium bicarbonate, tridecyltrimethylammonium bicarbonate, tetradecyltrimethylammonium bicarbonate, heptadecyltrimethylammonium bicarbonate, hexadecyltrimethylammonium bicarbonate, heptadecyltrimethylammonium bicarbonate Salt, octadecyltrimethylammonium bicarbonate, (2-hydroxypropyl) trimethylammonium bicarbonate, hydroxyethyltrimethylammonium bicarbonate, 1-methyl-1-azania-4-azabicyclo [2,2,2] octanium bicarbonate Salt, or quaternary ammonium hydrogen carbonate such as 1,1-dimethyl-4-methylpiperidinium hydrogen carbonate, tetramethylammonium carbonate, methyltrie Ruammonium carbonate, ethyltrimethylammonium carbonate, propyltrimethylammonium carbonate, butyltrimethylammonium carbonate, pentyltrimethylammonium carbonate, hexyltrimethylammonium carbonate, heptyltrimethylammonium carbonate, octyltrimethylammonium carbonate, nonyltrimethylammonium Carbonate, decyltrimethylammonium carbonate, undecyltrimethylammonium carbonate, dodecyltrimethylammonium carbonate, tridecyltrimethylammonium carbonate, tetradecyltrimethylammonium carbonate, heptadecyltrimethylammonium carbonate, hexadecyltrimethylammonium carbonate, Heptadecyltrimethylammonium carbonate, octadecyltrimethyla Ammonium carbonate, (2-hydroxypropyl) trimethylammonium carbonate, hydroxyethyltrimethylammonium carbonate, 1-methyl-1-azania-4-azabicyclo [2,2,2] octonium carbonate, or 1,1-dimethyl Quaternary ammonium carbonates such as -4-methylpiperidinium carbonate, hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxypropylammonium and triethylhydroxyethylammonium, weak organic acid salts, acetic acid, propionic acid, Examples include alkali metal salts of carboxylic acids such as butyric acid, caproic acid, capric acid, valeric acid, octylic acid, myristic acid and naphthenic acid.
Moreover, these isocyanurate-ized catalysts can be used individually or in combination of 2 or more types. In addition, the usage-amount of an isocyanurate-ized catalyst has preferable 0.001-0.1 mass% with respect to the total mass of monool and / or a polyol, and 1, 6- hexamethylene diisocyanate, 0.005-0 0.03 mass% is more preferable. When it is less than the lower limit, isocyanurate-modified polyisocyanate is not produced so much, the amount of by-product of urethane-modified polyisocyanate increases, and the average number of functional groups of the resulting polyisocyanate decreases. Moreover, when exceeding an upper limit, there exists a possibility of causing turbidity.

Polyisocyanate (A) includes 2,4'-diphenylmethane diisocyanate (A1) and hexamethylene diisocyanate-modified polyisocyanate (A2) having an average functional group number of 3 to 7 obtained above. Aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, araliphatic diisocyanate excluding 2,4'-diphenylmethane diisocyanate (A2) as long as it does not decrease, isocyanurate group-containing polyisocyanate obtained from these diisocyanates, uretdione Group-containing polyisocyanate, uretdione group and isocyanurate group-containing polyisocyanate, urethane group-containing polyisocyanate, allophanate group-containing polyisocyanate, burette group-containing polyisocyanate It can be exemplified uretonimine group-containing polyisocyanates, alone, or two or more may be used in combination.

<Aromatic diisocyanate>
Specific examples of such aromatic diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate mixture, m-xylylene diisocyanate. , P-xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, diphenylmethane diisocyanate polynuclear condensate (polyphenylene polymethylene polyisocyanate), 4,4′-diphenyl ether diisocyanate, 2-nitrodiphenyl- 4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'- Examples include phenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate. .

<Aliphatic diisocyanate>
Specific examples of the aliphatic diisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, and trioxyethylene diisocyanate. Can be mentioned.

<Alicyclic diisocyanate>
Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate and the like.

<Aromatic aliphatic diisocyanate>
Specific examples of the araliphatic diisocyanate include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate or a mixture thereof, 1,3-bis (1-isocyanato-1-methylethyl) benzene, or 1 , 4-bis (1-isocyanato-1-methylethyl) benzene or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, and the like.

Next, the polyol (B) used in the polyurethane elastomer-forming composition for roll elastic members of the present invention will be described in detail.
The polyol (B) of the present invention is not particularly limited as long as the effects of the present invention are achieved. From the viewpoint of improving mechanical properties, elastic recovery against vibration and compression set, the average number of functional groups is 2 to 3. It is preferable that at least one selected from polyester polyols, polyether polyols, and polycarbonate polyols having a number average molecular weight of 250 to 5000 is selected.

<Polyester polyol>
Specific examples of polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, Dicarboxylic acids such as sebacic acid, 1,4-cyclohexyl dicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α, β-diethylsuccinic acid, maleic acid, fumaric acid, etc. Or one or more of these anhydrides and the like, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1, -Nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, One or more low molecular weight polyols having a molecular weight of 500 or less, such as dimer acid diol, bisphenol A ethylene oxide and propylene oxide adducts, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, pentaerythritol And those obtained from the polycondensation reaction. In addition, a polyester-amide polyol obtained by replacing a part of the low molecular polyol with a low molecular polyamine such as hexamethylene diamine, isophorone diamine or monoethanolamine or a low molecular amino alcohol can also be used.

<Polyether polyol>
Specific examples of the polyether polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, , 5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene Glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, bisphenol A, bis (β-hydroxyethyl) benzene, xylylene glycol, glycerin, trimethylolpropane, penta Small molecules such as erythritol Initiates compounds having 2 or more, preferably 2-3 active hydrogen groups such as diols or low molecular weight polyamines such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, xylylenediamine, etc. As an agent, polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc., or alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether And polyether polyols obtained by ring-opening polymerization of cyclic ether monomers such as tetrahydrofuran.

<Polycarbonate polyol>
Specific examples of the polycarbonate polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5- Pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neo Pentyl glycol, diethylene glycol, dipropylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, dimer acid diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis (β-hydroxyethyl) benze One or more low-molecular polyols such as xylylene glycol, glycerin, trimethylolpropane, pentaerythritol, dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, diphenyl carbonate, di Examples thereof include those obtained from a dealcoholization reaction or a dephenol reaction with diaryl carbonates such as naphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindanyl carbonate, and tetrahydronaphthyl carbonate.

The polyol (B) can be used alone or in combination of two or more kinds of polyolefin polyols, acrylic polyols, silicone polyols, castor oil-based polyols, and fluorine-based polyols as long as the performance does not deteriorate.

<Polyolefin polyol>
Specific examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, hydrogenated polyisoprene and the like.

<Acrylic polyol>
Examples of the acrylic polyol include acrylic acid ester and / or methacrylic acid ester (hereinafter referred to as (meth) acrylic acid ester), acrylic acid hydroxy compound and / or methacrylic acid having at least one hydroxyl group in the molecule that can be a reaction point. Examples thereof include those obtained by copolymerizing an acrylic monomer using a thermal compound, a light energy such as an ultraviolet ray or an electron beam, and the like with a hydroxy compound (hereinafter referred to as a (meth) acrylic acid hydroxy compound) and a polymerization initiator.

<(Meth) acrylic acid ester>
Specific examples of (meth) acrylic acid esters include alkyl esters having 1 to 20 carbon atoms. Specific examples of such (meth) acrylate esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) such as hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate Alkyl acrylates, esters of (meth) acrylic acid with cycloaliphatic alcohols such as cyclohexyl (meth) acrylate, phenyl (meth) acrylate, (meth) acrylic acid allyl esters such as benzyl (meth) acrylate Can be mentioned. Such (meth) acrylic acid esters can be used singly or in combination of two or more.

<(Meth) acrylic acid hydroxy compound>
Specific examples of the (meth) acrylic acid hydroxy compound have at least one hydroxyl group in the molecule that can be a reaction point with the polyisocyanate composition. Specifically, 2-hydroxyethyl acrylate, 2 -Hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 3-hydroxy-2,2-dimethylpropyl acrylate, and acrylic acid hydroxy compounds such as pentaerythritol triacrylate. Moreover, methacrylic acid hydroxy compounds, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethylpropyl methacrylate, and pentaerythritol trimethacrylate, are mentioned. These acrylic acid hydroxy compounds and / or methacrylic acid hydroxy compounds can be used singly or in combination of two or more.

<Polymerization initiator>
Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator, and are appropriately selected depending on the polymerization method.
Specific examples of the thermal polymerization initiator include peroxydicarbonates such as di-2-ethylhexyl peroxydicarbonate, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl carbonate, Peroxyesters such as t-hexylperoxyisopropyl carbonate, di (t-butylperoxy) -2-methylcyclohexane, di (t-butylperoxy) 3,3,5-trimethylcyclohexane and di (t-butylperoxy) cyclohexane Peroxyketals and the like.
Specific examples of the photopolymerization initiator include acetophenone, methoxyacetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, α-hydroxy-α, α ′. -Acetophenones such as dimethylacetophenone, 2-hydroxy-2-cyclohexylacetophenone, 2-methyl-1 [4- (methylthio) phenyl] -2-montforinopropanone-1, benzoin, benzoin methyl ether, benzoin ethyl ether Benzoin ethers such as benzoin isopropyl butyl ether, benzophenone, 2-chlorobenzophenone, p, p'-dichlorobenzophenone, N, N'-tetramethyl-4,4'-diaminobenzophenone, 4- (2-hydroxy Ketones such as ethoxy) phenyl (2-hydroxy-2-propyl) ketone, thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, phosphine oxides such as bisacylphosphine oxide and benzoylphosphine oxide And ketals such as benzyldimethyl ketal and quinones such as camphan-2,3-dione and phenanthrenequinone.

<Silicone polyol>
Specific examples of the silicone polyol include a vinyl group-containing silicone compound obtained by polymerizing γ-methacryloxypropyltrimethoxysilane and the like, and α, ω-dihydroxypolydimethylsiloxane having at least one terminal hydroxyl group in the molecule, α, Mention may be made of polysiloxanes such as ω-dihydroxypolydiphenylsiloxane.

<Castor oil-based polyol>
Specific examples of the castor oil-based polyol include linear or branched polyester polyols obtained by a reaction between a castor oil fatty acid and a polyol. Dehydrated castor oil, partially dehydrated castor oil partially dehydrated, and hydrogenated castor oil added with hydrogen can also be used.

<Fluorine-based polyol>
A specific example of the fluorine-based polyol is a linear or branched polyol obtained by a copolymerization reaction using a fluorine-containing monomer and a monomer having a hydroxy group as essential components. Here, the fluorine-containing monomer is preferably a fluoroolefin, for example, tetrafluoroethylene, chlorotrifluoroethylene, trichlorofluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride, trifluoromethyl trifluoroethylene. Is mentioned. Examples of the monomer having a hydroxyl group include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether, hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether, and hydroxyalkyl vinyl crotonates. And monomers having a hydroxyl group such as a hydroxyl group-containing vinyl carboxylate or an allyl ester.

For the purpose of adjusting the hardness, the polyol (B) of the present invention can be used in combination with low molecular weight polyols having a molecular weight of 500 or less described for the polyester polyol.

Moreover, an additive can be further used in the polyurethane elastomer-forming composition for roll elastic members of the present invention as long as the performance is not deteriorated. Additives include lubricants, plasticizers, hydrolysis inhibitors, antioxidants, UV absorbers, UV stabilizers, pigments, dyes, fillers, antistatic agents, flame retardants, antiblocking agents, reinforcing fibers, A dispersant, a catalyst, a storage stabilizer and the like can be appropriately blended.

Next, a method for molding a roll elastic member using the polyurethane elastomer-forming composition for roll elastic member obtained in the present invention will be described.
<Method of forming roll elastic member>
First step: The polyisocyanate (A) of the polyurethane elastomer-forming composition for roll elastic member obtained in the present invention and the polyol (B) were stirred and mixed so as to be uniform at room temperature, and then included by stirring. Air bubbles are defoamed with a vacuum defoamer.
Second step: The polyurethane elastomer-forming composition for a roll elastic member in the first step is cast in a mold heated to 40 to 150 ° C in advance, and is cured by heating at 40 to 150 ° C for 1 to 12 hours.
Third step: After curing, the roll elastic member is removed from the mold and subjected to aging treatment at room temperature for one week.

The glass transition point of the roll elastic member thus obtained is preferably 0 ° C. or lower, and if it exceeds the upper limit value, there is a risk of performance variations due to the use environment.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Synthesis of hexamethylene diisocyanate-modified polyisocyanate (A2)>
<Synthesis Example 1>
In a 1000 ml four-necked flask equipped with a stirrer, thermometer, condenser, and dropping funnel, hexamethylene diisocyanate (Nippon Polyurethane Industry Co., Ltd., NCO content: 49.9% by mass, hereinafter referred to as HDI) was added. 950 g and 50 g of 3-methyl-1,5-pentanediol were charged, and urethanization reaction was performed at 80 ° C. for 2 hours under a nitrogen stream. Thereafter, 0.1 g of zirconyl octylate (manufactured by Daiichi Rare Element Chemical Industries, Ltd., zirconium octylate, hereinafter referred to as OctZr) was added, and an allophanatization reaction was performed at 110 ° C. for 2 hours. After the NCO content reached 40.3% by mass, 0.11 g of JP-508 (manufactured by Johoku Chemical Industry Co., Ltd., acidic phosphate ester) was added to perform a stop reaction, and the reaction solution was cooled to room temperature.
The reaction solution was subjected to thin-film distillation at 130 ° C. × 0.04 kPa to remove unreacted HDI, thereby obtaining a purified allophanate-modified polyisocyanate.
The allophanate-modified polyisocyanate has an NCO content of 19.3% by mass, an appearance of a transparent liquid, a number average molecular weight of 1100, an average functional group number calculated from the NCO content and the number average molecular weight of 4.9, and a viscosity at 25 ° C. 2000 mPa · s and free HDI content was 0.1% by mass. Further, the allophanate group content in all the linking groups was 90 mol%, the nurate group content was 3 mol%, and the urethane group content was 7 mol%.

<NMR: measurement of allophanate group / nurate group / urethane group content>
(1) Measuring device: “ECX400M” (manufactured by JEOL Ltd., 1H-NMR)
(2) Measurement temperature: 23 ° C
(3) Sample concentration: 0.1 g / 1 ml
(4) Integration count: 16
(5) Relaxation time: 5 seconds (6) Solvent: Deuterium dimethyl sulfoxide (7) Chemical shift criteria: Hydrogen atom signal of methyl group in deuterium dimethyl sulfoxide (2.5 ppm)
(8) Evaluation method: signal of hydrogen atom bonded to nitrogen atom of allophanate group near 8.5 ppm, signal of hydrogen atom of methylene group adjacent to nitrogen atom of nurate group near 3.7 ppm, and around 7.0 ppm The content of the linking group was measured from the area ratio of the signal of the hydrogen atom bonded to the nitrogen atom of the urethane group.

<GPC: Measurement of molecular weight>
(1) Measuring instrument: HLC-8220 (manufactured by Tosoh Corporation)
(2) Column: TSKgel (manufactured by Tosoh Corporation)
・ G3000H-XL
・ G2500H-XL
・ G2000H-XL, G1000H-XL
(3) Carrier: THF (tetrahydrofuran)
(4) Detector: RI (refractive index) detector (5) Temperature: 40 ° C
(6) Flow rate: 1.000 ml / min
(7) Calibration curve: Standard polystyrene (manufactured by Tosoh Corporation)
F-80 (molecular weight: 7.06 × 10 ⁵ , molecular weight distribution: 1.05)
F-20 (molecular weight: 1.90 × 10 ⁵ , molecular weight distribution: 1.05)
F-10 (molecular weight: 9.64 × 10 ⁴ , molecular weight distribution: 1.01)
F-2 (molecular weight: 1.81 × 10 ⁴ , molecular weight distribution: 1.01)
F-1 (molecular weight: 1.02 × 10 ⁴ , molecular weight distribution: 1.02)
A-5000 (molecular weight: 5.97 × 10 ³ , molecular weight distribution: 1.02)
A-2500 (molecular weight: 2.63 × 10 ³ , molecular weight distribution: 1.05)
A-500 (molecular weight: 5.0 × 10 ² , molecular weight distribution: 1.14)
(8) Sample solution concentration: 0.5% THF solution

<Synthesis Example 2>
A 1000 ml four-necked flask equipped with a stirrer, thermometer, condenser, and dropping funnel is charged with 985 g of HDI and 15 g of 1,3-butanediol, and subjected to urethanation reaction at 80 ° C. for 2 hours under a nitrogen stream. went. Thereafter, 0.1 g of 2-hydroxypropyltrimethylammonium octylate (trade name: DABCO TMR, manufactured by Air Products Japan) was added, and an isocyanuration reaction was performed at 60 ° C. for 2 hours. After the NCO content reached 41.5% by mass, 0.18 g of JP-508 was added to stop the reaction, and the reaction solution was cooled to room temperature.
The reaction solution was subjected to thin-film distillation at 130 ° C. × 0.04 kPa to remove unreacted HDI, thereby obtaining a purified isocyanurate-modified polyisocyanate.
The isocyanurate-modified polyisocyanate has an NCO content of 21.0% by mass, an external appearance of a transparent liquid, a number average molecular weight of 700, an average functional group number calculated from the NCO content and the number average molecular weight of 3.5, and a viscosity at 25 ° C. Was 3000 mPa · s, and the free HDI content was 0.3% by mass. In addition, the allophanate group content in all linking groups was 29 mol%, the nurate group content was 48 mol%, and the urethane group content was 23 mol%.

Tables 1 and 2 show the blending ratio of the polyurethane elastomer-forming composition for roll elastic members.

Abbreviations of the raw materials used in Table 1 and Table 2 are as follows.
(1) Millionate NM100: 2,4′-MDI / 4,4′-MDI (mass ratio) = 90/10, NCO content = 33.5 mass% (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(2) Millionate NM: 2,4′-MDI / 4,4′-MDI (mass ratio) = 55/45, NCO content = 33.5 mass% (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(3) Millionate MTL: carbodiimide-modified diphenylmethane diisocyanate, NCO content = 29.1% by mass (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(4) Millionate MR-200: polymethylene polyphenyl polyisocyanate, NCO content = 31.1 mass% (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(5) Coronate 2770: Allophanate-modified HDI, NCO content = 19.4 mass%, average functional group number = 2.0 (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(6) ON-300: Succinic acid polyester polyol, hydroxyl value = 59.5 KOH mg / g, number average molecular weight = 1890 (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(7) Nippon Run 980R: Polycarbonate polyol, hydroxyl value = 55.9 KOH mg / g, number average molecular weight = 2010 (manufactured by Nippon Polyurethane Industry Co., Ltd.)
(8) PCD-1000: 1,6-hexanediol-based polycarbonate polyol reaction preparation, hydroxyl value = 114.0 KOH mg / g, number average molecular weight = 980 (manufactured by Nippon Polyurethane Industry Co., Ltd.)

<Molding method>
Polyisocyanate (A) heated to 40 ° C. and polyol (B) heated to 80 ° C. were mixed at a blending ratio (α value) shown in Table 1, and stirred for 1 minute with an agitator mixer. Then, it was degassed for 2 minutes and poured into a 2 mm thick flat mold heated at 120 ° C. The flat mold was cured by heating at 120 ° C. for 10 hours, and an evaluation sheet was produced by aging treatment at room temperature for one week.

Tables 3 and 4 show various physical properties of the obtained sheet.

As shown in Table 3 above, the sheets obtained from the polyurethane elastomer-forming compositions for roll elastic members of Examples 1 to 6 were compared with the comparative examples of Table 4 in terms of pot life, elastic recovery, and It was found that the mechanical properties were excellent.

(1) Evaluation test 1:
<Pot life>
Polyisocyanate (A) adjusted to 80 ° C. and polyol (B) adjusted to 40 ° C. were adjusted so that the total mass was 250 g, and stirred for 30 seconds with an agitator mixer. Thereafter, 200 g is put into a glass bottle (trade name: PS-13K, manufactured by Daiichi Glass Co., Ltd.), and after 1 minute of stirring, the glass bottle is put into an 80 ° C. oil bath, and the time until the viscosity reaches 80 Pa · s with a B-type viscometer. Was measured.

(2) Evaluation test 2:
<Sheet physical properties>
According to JIS K7312 “Physical Test Method for Thermosetting Polyurethane Elastomer Moldings”, JIS-A hardness, tensile strength measurement, and impact resilience were measured.

(3) Evaluation test 3:
<Creep and elastic recovery>
Crepe properties and elastic recoverability were measured with an IRHD M detector using a Burleys Digitest. For the creep property, the hardness 0.1 seconds after the start of measurement was measured, and the hardness retention with respect to the initial hardness was measured. The elastic recoverability was determined by releasing the load 30 seconds after the start of measurement (immediately after releasing the load), measuring the hardness 30 seconds after releasing the load, and measuring the hardness recovery rate relative to the initial hardness.

<Evaluation criteria for elastic recovery>
・ Recovery of hardness after 30 seconds of load release is 95% or more (pass, evaluation: ○)
・ Recovery of hardness after 30 seconds of load release is 90% to less than 95% (pass, evaluation: Δ)
・ Recovery of hardness after 30 seconds of load release is less than 90% (failed, evaluation: x)

Claims (2)

In the polyurethane elastomer-forming composition for roll elastic members comprising at least polyisocyanate (A) and polyol (B),
The polyisocyanate (A) contains 2,4′-diphenylmethane diisocyanate (A1) and hexamethylene diisocyanate-modified polyisocyanate (A2) having an average functional group number of 3 to 7,
The total amount of 2,4′-diphenylmethane diisocyanate (A1) and hexamethylene diisocyanate modified polyisocyanate (A2) is at least 60% by mass or more based on polyisocyanate (A),
The mass ratio between (A1) and (A2) is (A1) / (A2) = 30/70 to 75/25,
And forming a polyurethane elastomer for a roll elastic member, wherein the hexamethylene diisocyanate-modified polyisocyanate (A2) is allophanate-modified polyisocyanate (A2-1) and / or isocyanurate-modified polyisocyanate (A2-2) Sex composition. A roll elastic member having a JIS-A hardness of 20 to 70 in a roll elastic member obtained by thermosetting the polyurethane elastomer-forming composition for roll elastic member according to claim 1.