JP2015081278A - Urethane composition and urethane elastomer molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an urethane composition excellent in flexibility, strength and water resistance.SOLUTION: The urethane composition is provided that contains: a main agent (i) containing an urethane prepolymer (A) having an isocyanate group obtained by reacting polycarbonate polyol (a1), polyether polyol (a2) and polyisocyanate (a3); and a curing agent (ii) containing a compound containing a hydroxyl group (B). An urethane elastomer molded article is also provided that is obtained by using the urethane composition. The polycarbonate polyol (a1) is preferably obtained with 1,6-hexane diol as a raw material. The polyisocyanate (a3) is preferably 4,4'-diphenyl methane diisocyanate.

Description

  The present invention relates to a urethane composition excellent in flexibility, strength and water resistance.

  Urethane elastomers are widely used in the fields of various roll members, industrial belts, tires and the like because of their excellent flexibility and mechanical strength.

  As a urethane composition used for a urethane elastomer, for example, a urethane composition containing a urethane prepolymer obtained by reacting a polyether polyol, a polyisocyanate, and a blocking agent (C) and a triamine compound is disclosed. (For example, refer to Patent Document 1).

  However, when a polyether polyol is used alone as a raw material for the urethane prepolymer in the urethane composition, there is a problem that desired strength and water resistance cannot be obtained. Moreover, the urea bond produced | generated with the said triamine compound has further reduced water resistance.

JP 2012-21113 A

  The problem to be solved by the present invention is to provide a urethane composition excellent in flexibility, strength and water resistance.

  The present invention relates to a main component (i) containing a urethane prepolymer (A) having an isocyanate group obtained by reacting a polycarbonate polyol (a1), a polyether polyol (a2) and a polyisocyanate (a3), and a compound having a hydroxyl group. A urethane composition containing a curing agent (ii) containing (B), and a urethane elastomer molded article obtained by using the urethane composition.

  The urethane composition of the present invention is excellent in flexibility, strength and water resistance. The urethane prepolymer (A) used in the present invention is also excellent in storage stability. Therefore, the urethane composition of the present invention is suitable for production of industrial rolls such as papermaking rolls, steel rolls and printing rolls; industrial belts such as conveyor belts and papermaking shoe press belts; industrial tires such as solid tires. Can be used for

  Examples of the polycarbonate polyol (a1) include those obtained by reacting a carbonate ester and / or phosgene with the compound having two or more active hydrogens.

  As the carbonate ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used. These carbonates may be used alone or in combination of two or more.

  Examples of the compound having two or more active hydrogens include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2 , 5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2- Methyl-1,3-propanediol, neopentylglycol 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin Aliphatic polyols such as trimethylolpropane, ditrimethylolpropane, trimethylolpropane and pentaerythritol; Alicyclic polyols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; Alkylene oxide adducts of bisphenol A and bisphenol A Bisphenol S, alkylene oxide adducts of bisphenol S, and the like can be used. These polyols may be used alone or in combination of two or more. Among these, it is preferable to use an aliphatic polyol, and it is more preferable to use 1,6-hexanediol from the viewpoint of maintaining flexibility and strength and further improving low viscosity and water resistance.

  The number average molecular weight of the polycarbonate polyol (a1) is preferably in the range of 500 to 5,000, more preferably in the range of 800 to 4,000, from the viewpoint of flexibility, strength, and water resistance. In addition, the number average molecular weight of the said polycarbonate polyol (a1) shows the value measured on condition of the following by gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

  Examples of the polyether polyol (a2) that can be used include polyethylene polyol, polypropylene polyol, polytetramethylene polyol, polyoxyethylene polyoxypropylene polyol, and the like. These polyether polyols may be used alone or in combination of two or more. Among these, it is preferable to use polyethylene polyol and polytetramethylene polyol from the viewpoints of flexibility, strength, and water resistance.

  The number average molecular weight of the polyether polyol (a2) is preferably in the range of 500 to 5,000, more preferably in the range of 800 to 4,000, from the viewpoints of flexibility, strength, and water resistance. In addition, the number average molecular weight of the said polyether polyol (a2) shows the value measured similarly to the number average molecular weight of the said polycarbonate polyol (a1).

  As mass ratio [(a1) / (a2)] of the said polycarbonate polyol (a1) and the said polyether polyol (a2), from the point which can improve water resistance further, in the range of 40 / 60-80 / 20. It is preferable that the range is 50/50 to 70/30.

  In the present invention, other polyols may be used in combination with the polycarbonate polyol (a1) and the polyether polyol (a2) as necessary.

  Examples of the other polyol include polyester polyol, polybutadiene polyol, dimer diol, the compound having two or more active hydrogens, and the like. These polyols may be used alone or in combination of two or more.

  Examples of the polyisocyanate (a3) include diphenylmethane diisocyanate (4,4′-form, 2,4′-form, 2,2′-form, or a mixture thereof), a carbodiimide-modified form of diphenylmethane diisocyanate, and a nurate. Modified forms, modified forms of burette, modified forms of urethane imine, modified forms of diphenylmethane diisocyanate such as modified forms of polyol modified with polyols having a number average molecular weight of 1,000 or less such as diethylene glycol and dipropylene glycol, tolylene diisocyanate, tolidine diisocyanate, polymethylene Aromatic polyisocyanates such as polyphenyl polyisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylene diisocyanate; isophorone diisocyanate Sulfonates, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, alicyclic polyisocyanates such as norbornene diisocyanate; hexamethylene diisocyanate, and aliphatic polyisocyanates such as dimer acid diisocyanate can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, aromatic polyisocyanate is preferably used, and 4,4′-diphenylmethane diisocyanate is more preferably used from the viewpoint that water resistance can be further improved.

  Moreover, when using together the said 4,4'- diphenylmethane diisocyanate and other polyisocyanate, content of 4,4'-diphenylmethane diisocyanate is 80 mass% or more in all the polyisocyanates from a water-resistant point. Is preferable, and it is more preferable that it is 90 mass% or more.

  The polycarbonate polyol (a1), the polyether polyol (a2), and the polyisocyanate (a3) are reacted in terms of flexibility, strength, and water resistance. The polycarbonate polyol (a1) and the polyether polyol (a2) It is preferable that the molar ratio (NCO / OH) of the total hydroxyl group of the polyisocyanate (a3) to the isocyanate group of the polyisocyanate (a3) is 1.5 to 30, more preferably 2 to 20, The range of 4-15 is more preferable.

  The urethane prepolymer (A) obtained by the above method has an isocyanate group, and as its isocyanate group equivalent (hereinafter abbreviated as “NCO equivalent”), water resistance can be further improved, 150-1,000 g / eq. It is preferable that it is the range of 200-500 g / eq. The range of is more preferable.

  Examples of the compound (B) having a hydroxyl group include ethylene glycol, diethylene recall, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, and 1,4-butanediol. , Hexamethylene glycol, saccharose, methylene glycol, glycerin, sorbitol, bisphenol A, 4,4′-dihydroxydiphenyl, 4,4′-dihydroxydiphenyl ether, trimethylolpropane and the like can be used. These compounds can be used alone or in combination of two or more. Among these, it is preferable to use 1,4-butanediol from the viewpoint that water resistance can be further improved.

  If necessary, a compound having an amino group may be used in combination with the compound (B) having a hydroxyl group.

  Examples of the compound having an amino group include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4′- Dicyclohexylmethanediamine, 3,3′-dimethyl-4,4′-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, hydrazine, diethylenetriamine, triethylenetetramine, 3,3 '-Dichloro-4,4'-diaminodiphenylmethane or the like can be used. These compounds may be used alone or in combination of two or more.

  When the compound having an amino group is used, a urea bond is formed in the obtained urethane elastomer molded article. The amount of urea bond in the urethane composition of the present invention is 2 mol particularly from the viewpoint of water resistance. / Kg or less is preferable, and 1 mol / kg or less is more preferable.

  The reaction between the urethane prepolymer (A) and the compound (B) is, from the viewpoint of flexibility, strength and water resistance, an isocyanate group contained in the urethane prepolymer (A) and a hydroxyl group contained in the compound (B). The molar ratio (NCO / OH) is preferably in the range of 0.9 to 1.1.

  The urethane composition of the present invention comprises the main component (i) containing the urethane prepolymer (A) and the curing agent (ii) containing the compound (B) as essential components. And may contain other additives.

  Examples of the other additives include catalysts, foam stabilizers, abrasive grains, fillers, pigments, thickeners, hydrolysis inhibitors, antioxidants, ultraviolet absorbers, surfactants, flame retardants, and plasticizers. Etc. can be used. These additives may be contained alone or in the main agent (i) and the curing agent (ii) as long as the effects of the present invention are not impaired.

  Next, a method for producing a urethane elastomer molded product will be described.

  Examples of the method for producing the urethane elastomer molded product include a method using a mixed casting machine.

  Specifically, first, the main agent (i) and the curing agent (ii) are put into respective tanks of a mixed casting machine and mixed to obtain a urethane composition.

  Next, after the state injected into the mold is heated and held at 40 to 150 ° C. for about 30 minutes to 2 hours, it is preferably after-cured at 80 to 120 ° C. for 8 to 17 hours. The method of obtaining is mentioned.

  Hereinafter, the present invention will be described in more detail with reference to examples.

[Example 1]
In a four-necked flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, 389 parts by mass of 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”), Crude MDI (Nippon Polyurethane Industry Co., Ltd.) “Millionate MR-200” (hereinafter abbreviated as “crude MDI”). 20 parts by mass were charged and stirring was started. Next, 295 parts by mass of polycarbonate polyol ("ETERRNACOLL UH-200" manufactured by Ube Industries, Ltd., 1,6-hexanediol type polycarbonate polyol, number average molecular weight; 2,000, hereinafter abbreviated as "PC-1"). , Polyethylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PEG1000”) 59 parts by mass, polytetramethylene glycol (number average molecular weight; 1,000, hereinafter abbreviated as “PTMG1000”) 236 parts by mass Were mixed and reacted at 80 ° C. for 5 hours under a nitrogen stream to obtain a urethane prepolymer having an NCO equivalent of 420 isocyanate groups, which was used as a main agent.
Next, using 1,4-butanediol as a curing agent, the molar ratio (NCO / OH) between the isocyanate group of the urethane prepolymer and the hydroxyl group of the 1,4-butanediol is 1.05. Both were stirred and mixed, and the mixture was poured into a mold heated to 80 ° C. Immediately after closing the mold, the mold is allowed to stand in a dryer at 80 ° C. for 1 hour and then aftercured at 110 ° C. for 16 hours to form a cylindrical urethane elastomer molded product having a diameter of 29 mm and a height of 12.5 mm, and a sheet A molded urethane elastomer molded product was obtained.

[Examples 1 to 6]
A cylindrical urethane elastomer molded product and a sheet-like urethane elastomer molded product were obtained in the same manner as in Example 1 except that the materials used were changed as shown in Table 1.

[Comparative Example 1]
Into a four-necked flask equipped with a nitrogen introduction tube, a condenser for cooling, a thermometer, and a stirrer, 230 parts by mass of 2,4-toluene diisocyanate (hereinafter abbreviated as “TDI”) was charged, and stirring was started. Next, 539 parts by mass of PC-1, 115 parts by mass of polyethylene glycol (number average molecular weight; 400, hereinafter abbreviated as “PEG400”), polytetramethylene glycol (number average molecular weight; 1,500, hereinafter “PTMG1500”) (Abbreviated.) 115 parts by mass were charged and mixed, and reacted at 80 ° C. for 5 hours under a nitrogen stream to obtain a urethane prepolymer having an isocyanate group of NCO equivalent; 730, which was used as a main agent.
Subsequently, using 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter abbreviated as “MOCA”) as a curing agent, the isocyanate group of the urethane prepolymer (A-1) and the MOCA Both were stirred and mixed so that the molar ratio (NCO / NH) to the active hydrogen group of the mixture was 1.05, and the mixture was poured into a mold heated to 80 ° C. Immediately after closing the mold, the mold is left in a dryer at 80 ° C. for 1 hour and then after-cured at 110 ° C. for 16 hours to obtain a cylindrical urethane elastomer molded product having a diameter of 29 mm and a height of 12.5 mm, and a thickness. A sheet-like urethane elastomer molded product having a thickness of 12.5 mm was obtained.

[Comparative Examples 2 to 4]
A cylindrical urethane elastomer molded article and a sheet urethane elastomer molded article were obtained in the same manner as in Comparative Example 1 except that the materials used were changed as shown in Table 2.

[Flexibility evaluation method]
The circular urethane elastomer molded products obtained in the examples and comparative examples were processed using a dumbbell-shaped No. 3 punching blade to obtain test pieces. Using the tensile tester “Autograph AG-I” (manufactured by Shimadzu Corporation) in accordance with JIS-K6301, the test piece was subjected to a crosshead speed of 300 mm / min in an atmosphere at a temperature of 23 ° C. and a humidity of 60%. And 100% modulus (MPa) of the test piece was measured to evaluate the flexibility.

[Strength evaluation method]
Tensile tests similar to those described in [Method for evaluating flexibility] were performed, and tensile strength (MPa), elongation (%), and tear strength (kN / m) were measured to evaluate the strength.

[Evaluation method of water resistance]
The water resistance was evaluated by the wet heat swelling rate and the elongation change amount.
(Measurement method of wet heat swelling rate)
The sheet-like urethane elastomer molded articles obtained in the examples and comparative examples were cut into 20 mm × 50 cm × 2 mm to obtain test pieces. The test piece was stored in a thermostat at 70 ° C. and a humidity of 95% for 1 month, and immediately after removal, the volume was measured using a digital caliper. The wet heat swelling rate (%) was calculated by the following formula (1) using the volume values before and after storage.
Wet heat swelling rate (%) = [(volume after storage / volume before storage) −1] × 100 (1)
(Measurement method of elongation change)
The circular urethane elastomer molded products obtained in the examples and comparative examples were processed using a dumbbell-shaped No. 3 punching blade to obtain test pieces. The test piece was stored in a constant temperature and humidity machine at 70 ° C. and 95% humidity for 1 month, and immediately after removal, the elongation (%) was measured by a tensile test in the same manner as in the above [Strength Measuring Method]. Using the elongation values before and after storage, the amount of change in elongation (%) was calculated by the following formula (2).
Elongation change (%) = [(Elongation after storage / Elongation before storage) -1] × 100 (2)

Abbreviations in Tables 1 and 2 will be described.
“DC-1800”: Polyether polyol (“Unisafe DC-1800” manufactured by NOF Corporation)
“PTMG2000”: polytetramethylene glycol (number average molecular weight; 2,000)
“1,4-BG”: 1,4-butanediol

  It turned out that Examples 1-6 which are urethane elastomer molded articles obtained using the urethane composition of this invention are excellent in a softness | flexibility, intensity | strength, and water resistance.

  On the other hand, Comparative Examples 1 to 4 are embodiments using 3,3'-dichloro-4,4'-diaminodiphenylmethane as a curing agent, but all have poor water resistance.

Claims (5)

A main component (i) containing a urethane prepolymer (A) having an isocyanate group obtained by reacting a polycarbonate polyol (a1), a polyether polyol (a2) and a polyisocyanate (a3), and a compound (B) having a hydroxyl group. A urethane composition comprising a curing agent (ii). The urethane composition according to claim 1, wherein the polycarbonate polyol (a1) is obtained using 1,6-hexanediol as a raw material. The urethane composition according to claim 1, wherein the polyisocyanate (a3) is 4,4'-diphenylmethane diisocyanate. The urethane composition according to claim 1, wherein the compound (B) having a hydroxyl group is 1,4-butanediol. A urethane elastomer molded article obtained by using the urethane composition according to any one of claims 1 to 4.