JP2017025191A - Polyurethane composition, and polyurethane molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane composition excellent in handleability and providing a molded body having practical strength, without using MOCA.SOLUTION: There is provided the polyurethane composition comprising: an urethane polymer composed of polyether polyol and tolylene diisocyanate; and only 2 kinds of amine curing agents of 3,5-diamino-4-chlorobenzoic acid 2-methylpropyl and dimethylthiotoluenediamine as curing agents.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polyurethane composition and a polyurethane molded product obtained by thermosetting the polyurethane composition.

  Thermosetting polyurethane is used as a raw material for power transmission belts, various rollers, blades, conveyor belts such as belt conveyors, solid tires, and squeegees for screen printing in OA equipment. As a curing agent for thermosetting polyurethane, 4,4′-methylenebis (2-chloroaniline) (hereinafter referred to as “MOCA”) is widely used. of Chemicals) is listed as a Substance of Very High Concern (SVHC), and may become a prohibited substance in the future.

Instead of MOCA, it is also conceivable to use amine-based curing agents such as diethyltoluenediamine and 3,5-diamino-4-chlorobenzoate 2-methylpropyl. However, diethyltoluenediamine reacts too quickly and cures before casting into the mold, while 2-methylpropyl 3,5-diamino-4-chlorobenzoate reacts too slowly to demold from the mold It takes a long time to do so, and any amine curing agent has a problem in handling properties. It is conceivable to use a slow-curing curing agent and a reaction accelerator in combination, but there is a balance between the stability that does not proceed until the casting and the reactivity that the curing reaction proceeds quickly after casting. Have difficulty.
In Patent Document 1, 3,5-dimethylthio-2,4-toluenediamine and 3,5-dimethylthio-2,6-toluenediamine are added as curing agents to a prepolymer having an NCO% of greater than 4.7%. Incorporated belt molding materials have been proposed.

Japanese Patent Laid-Open No. 2002-234928

  It is an object of the present invention to provide a polyurethane composition capable of obtaining a molded article having excellent handling properties and practical strength without using MOCA.

In order to solve the above problems, the configuration of the present invention is as follows.
1. A urethane prepolymer comprising a polyether polyol and tolylene diisocyanate;
A polyurethane composition comprising only two amine-based curing agents, 2-methylpropyl 3,5-diamino-4-chlorobenzoate and dimethylthiotoluenediamine, as a curing agent.
2. 1. A molar ratio of amino group of 2-methylpropyl 3,5-diamino-4-chlorobenzoate and dimethylthiotoluenediamine is in a range of 30/70 or more and 90/10 or less. The polyurethane composition described in 1.
3. An amino group (—NH ₂ ) of the curing agent;
1. The molar ratio (—NH ₂ / —NCO) of the urethane prepolymer to an isocyanate group (—NCO) is in the range of 0.8 or more and 0.98 or less. Or 2. The polyurethane composition described in 1.
4). 1. A dicarboxylic acid compound is included. ~ 3. The polyurethane composition according to any one of the above.
5.1. ~ 4. A polyurethane molded product obtained by thermally curing the polyurethane composition according to any one of the above.
6.5. A power transmission belt characterized in that the polyurethane molded body described in 1 is used as a belt body.

Since the polyurethane composition of the present invention does not contain MOCA, the load on the environment is small. In addition, the stability in which the curing reaction does not proceed until casting and the reactivity in which the curing reaction proceeds promptly after casting are balanced and have excellent handling properties. In the polyurethane composition containing the conventional MOCA Manufacturing conditions can be used almost as they are.
The polyurethane molded product obtained by thermosetting the polyurethane composition of the present invention has the same physical properties as a polyurethane molded product obtained by thermosetting a polyurethane composition containing conventional MOCA, and the polyurethane molded product using MOCA as a curing agent. Can be replaced.

The schematic of the toothed belt which is one embodiment of a power transmission belt.

The polyurethane composition of the present invention comprises a urethane prepolymer comprising a polyether polyol and tolylene diisocyanate,
As the curing agent, it contains only two amine curing agents, 2-methylpropyl 3,5-diamino-4-chlorobenzoate and dimethylthiotoluenediamine.
The polyurethane composition of the present invention uses the above-described two specific amine-based curing agents as curing agents and does not contain MOCA, and therefore has a low environmental impact. The polyurethane composition of the present invention has handling properties equivalent to those of a polyurethane composition containing MOCA, which is a currently widely used curing agent. That is, in the polyurethane composition of the present invention, the stability in which the curing reaction does not proceed until casting and the reactivity in which the curing reaction proceeds rapidly after casting are balanced. In the polyurethane composition of the present invention, the production conditions in the conventional polyurethane composition containing MOCA can be used almost as they are.
The polyurethane molded product obtained by thermosetting the polyurethane composition of the present invention has substantially the same physical properties as hardness, tensile rupture strength, elongation at break, tear strength, modulus, and the like, as compared with a polyurethane molded product thermoset using MOCA as a curing agent. Since the polyurethane molded product of the present invention has the same physical properties as the polyurethane molded product using MOCA as a curing agent, it can replace products in which the polyurethane molded product using MOCA as a curing agent is used.

"Urethane prepolymer"
The urethane prepolymer of the present invention is obtained by reacting a polyether polyol and tolylene diisocyanate. As the polyether polyol, polytetramethylene ether glycol, polypropylene glycol or the like can be suitably used. As the urethane prepolymer, those having an isocyanate group content of 2.0 to 10.0 wt% and a number average molecular weight of 500 to 4000 can be used. Examples of such urethane prepolymers include Hyprene L-100 (manufactured by Mitsui Chemicals), Pandex 4000 series (manufactured by DIC Corporation), Pandex P-800, 900 series (manufactured by DIC Corporation), Takenate. L-1100 series (Mitsui Chemicals Co., Ltd.) etc. can be utilized. The isocyanate group content is preferably 2.0 to 10.0 wt%, and more preferably 3.5 to 6.5 wt%. Here, in this invention, a number average molecular weight means the molecular weight computed from the hydroxyl value of the polyol measured according to JIS-K1557.

"Curing agent"
The polyurethane composition of the present invention has two kinds of amines, 2-methylpropyl 3,5-diamino-4-chlorobenzoate (hereinafter referred to as CDAB) and dimethylthiotoluenediamine (hereinafter referred to as DMTDA) as a curing agent. It contains only a hardener based on alcohol, and does not contain other hardeners such as alcohol-based hardeners such as 1,4-butanediol and trimethylolpropane, ethylenediamine and p-phenylenediamine.

“2-methylpropyl 3,5-diamino-4-chlorobenzoate”
The structural formula of CDAB is shown in the following chemical formula 1.

"Dimethylthiotoluenediamine"
DMTDA is a mixture of the isomers 3,5-dimethylthio-2,4-toluenediamine and 3,5-dimethylthio-2,6-toluenediamine. The structural formula of 3,5-dimethylthio-2,4-toluenediamine is shown in the following chemical formula 2, and the structural formula of 3,5-dimethylthio-2,6-toluenediamine is shown in the chemical formula 3 below. These isomers are inevitably produced in a mixed state when DMTDA is synthesized, and the mixing mass ratio thereof is 3,5-dimethylthio-2,4-toluenediamine / 3,5-dimethylthio- 2,6-toluenediamine = 80/20 to 90/10.

  CDAB and DMTDA are preferably mixed so that the molar ratio of each amino group (CDAB / DMTDA: hereinafter referred to as amine ratio) is in the range of 30/70 to 90/10. When the amine ratio is less than 30/70, the hardness and fracture strength are reduced, and physical properties equivalent to MOCA cannot be obtained. When the amine ratio is greater than 90/10, even if a reaction accelerator is used, the demolding time becomes long, and molding is difficult because it does not meet the current thermosetting conditions.

The polyurethane composition of the present invention includes a reaction accelerator, a plasticizer, a surfactant, a lubricant, a filler, a pigment, a dye, a hydrolysis inhibitor, an antioxidant, an ultraviolet absorber, a conductive agent, etc. Additives can be included.
In the polyurethane composition of the present invention, when the demolding time is long and the productivity is low, a reaction accelerator may be blended. As the reaction accelerator, a dicarboxylic acid compound selected from succinic acid, glutaric acid, adipic acid, pimelic acid, diglycolic acid, azelaic acid, oxybismethylenebisacetic acid and the like can be used. The reaction accelerator can be blended in an amount of 0.01 to 5 parts with respect to 100 parts of the prepolymer.
A plasticizer is a compound with low volatility that is mixed to lower the softening region and improve processability. For example, aromatic carboxylic acid esters such as phthalic acid esters, isophthalic acid esters, and maleic acid esters, Aliphatic carboxylic acid esters such as adipic acid ester, sebacic acid ester, dodecanoic acid ester, fumaric acid ester, trimellitic acid ester, citric acid ester, itaconic acid ester, oleic acid ester, stearic acid ester, ricinoleic acid ester, phenol type Examples thereof include sulfonic acid derivatives such as alkylsulfonic acid esters and butylbenzenesulfonamide, and phosphoric acid derivatives such as ethylhexyl diphenyl phosphate, triphenyl phosphate, and cresyl diphenyl phosphate.

  The polyurethane molded product obtained by thermosetting the polyurethane composition of the present invention can be used as various products without particular limitation. In particular, a product in which a polyurethane molded body containing MOCA is used can be preferably replaced. Specifically, it can be used for a transmission belt, a blade, and a roller.

Hereinafter, the manufacturing method of the power transmission belt which uses the polyurethane molded object which heat-cured the polyurethane composition of this invention as a belt main body is demonstrated.
The polyurethane composition of the present invention contains a prepolymer and a curing agent, and the molded product is produced by a prepolymer method.
In the prepolymer method, by adjusting the molecular weight of the prepolymer, the isocyanate fraction (NCO%) which is the ratio of the mass of the isocyanate group remaining in the prepolymer to the mass of the prepolymer, the mixing ratio of the curing agent, etc. By adding a plasticizer, the hardness of the polyurethane suitable for the belt can be adjusted.
In the polyurethane composition of the present invention, the NCO% of the prepolymer and the ratio of the number of moles of amino groups (—NH ₂ ) contained in the curing agent to the number of moles of isocyanate groups (—NCO) contained in the prepolymer (− NH ₂ / —NCO: hereinafter referred to as “α ratio”) is adjusted in the range of 0.8 to 0.98, and an appropriate amount of plasticizer is added, whereby the hardness of the polyurethane is 60 to 95 degrees (duro). Adjustment can be made within the range of A).

A schematic view of a toothed belt which is an embodiment of the transmission belt of the present invention is shown in FIG.
The toothed belt 1 is formed by a belt body in which a plurality of belt teeth 2 are provided on the inner peripheral surface at a predetermined pitch in the belt length direction. Further, a core wire 3 as a tensile body is provided along the bottom of each belt tooth 2 in a substantially spiral shape in the belt width direction and in the belt width direction.
The core 3 only needs to have an effective strength as a tensile body, and the material used is not particularly limited, and examples thereof include glass fiber, carbon fiber, aramid fiber, and polyester fiber. The shape of the transmission belt is not limited to a toothed belt, and may be a saddle belt, a flat belt, a round belt, or the like.

Next, the manufacturing method of the toothed belt by the prepolymer method will be described in order.
<Core set process>
A core wire is spirally wound around the outer peripheral surface of a cylindrical inner mold at a predetermined pitch. In the inner die, belt tooth forming grooves extending in the axial direction are formed at a predetermined pitch on the outer peripheral surface thereof.
<Mold setting process>
The inner mold is assembled in the center of the cylindrical outer mold so that a cavity for injecting a belt molding material is formed between the outer mold and the inner mold.

<Belt molding material preparation process>
Let terminal isocyanate group urethane prepolymer be A liquid. A mixture of CDAB and DMTDA and a mixture of additives as optional components are set as B liquid, and A liquid and B liquid are mixed to prepare a belt molding material.
<Belt molding material injection / curing process>
The obtained belt molding material is poured into a cavity between the outer mold and the inner mold, and this is heated to thermally cure the belt molding material.

<Demolding process>
The inner mold is pulled out in the axial direction, and the cylindrical belt precursor in which the belt molding material is cured is removed from the inner peripheral surface of the outer mold.
<Width cut process>
The removed belt precursor is cut into a predetermined width to obtain a toothed belt.
In addition, the said manufacturing method is an example and the power transmission belt of this invention is not limited to what was manufactured with the said manufacturing method.

  Next, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

"Example 1"
500 g of a prepolymer of polytetramethylene glycol and tolylene diisocyanate having an isocyanate group content of 4.3 wt% (trade name: Hyprene L-100, manufactured by Mitsui Chemicals Co., Ltd.) was used as A liquid, and then in a vacuum oven at 80 ° C. for 2 hours. Vacuum degassing was performed.
Adipic acid (Wako Pure Chemical Industries Co., Ltd.) was added to 51.2 g of a curing agent obtained by blending CDAB (Rhein Chemie, trade name: Addolinlink 1604) and DMTDA (Albemarle, trade name: Etacure 300) at an amine ratio of 30/70. (Company) 0.4 g and a dioctyl adipate (made by CG Esther Co., Ltd., hereinafter referred to as DOA) 200 g as a plasticizer were added as a B solution and heated to 120 ° C.
A liquid B at 120 ° C. was added into a cup of liquid A at 80 ° C. and mixed and stirred for 60 seconds to obtain a polyurethane composition. The polyurethane composition was poured into a sheet-shaped mold (split mold) having a cavity having a thickness of 2 mm, a width of 200 mm and a length of 180 mm, and reacted at a crosslinking temperature of 110 ° C. for 45 minutes to form a sheet having a thickness of 2 mm. The molded sheet was subjected to after cure at 80 ° C. for 12 hours to obtain a polyurethane sheet.

"Example 2"
A polyurethane sheet was molded in the same manner as in Example 1 except that the amount of adipic acid added was 0.8 g.
"Example 3"
A polyurethane sheet was molded in the same manner as in Example 1 except that 53.9 g of a crosslinking agent obtained by blending CDAB and DMTDA at an amine ratio of 70/30 was used, and the amount of adipic acid added was changed to 0.8 g.
Example 4
A polyurethane sheet was molded in the same manner as in Example 1 except that 55.2 g of a crosslinking agent obtained by blending CDAB and DMTDA at an amine ratio of 90/10 was used, and the amount of adipic acid added was changed to 0.8 g.

“Comparative Example 1”
A polyurethane sheet was molded in the same manner as in Example 1 except that 49.3 g of DMTDA was used and adipic acid was not added.
“Comparative Example 2”
A polyurethane sheet was molded in the same manner as in Example 1 except that 49.9 g of a crosslinking agent obtained by blending CDAB and DMTDA at an amine ratio of 10/90 was used.
“Comparative Example 3”
A polyurethane sheet was molded in the same manner as in Example 1 except that 55.8 g of a crosslinking agent obtained by blending CDAB and DMTDA at an amine ratio of 99/1 was used, and the amount of adipic acid added was changed to 0.8 g. However, since demolding was impossible in 45 minutes, a crosslinking reaction was performed for 60 minutes.
“Comparative Example 4”
A polyurethane sheet was molded in the same manner as in Example 1 except that 55.8 g of CDAB was used as a crosslinking agent and the amount of adipic acid added was 0.8 g. However, since demolding was impossible in 45 minutes, a crosslinking reaction was performed for 60 minutes.
"Comparative Example 5"
A polyurethane sheet was molded in the same manner as in Example 1 except that 61.5 g of MOCA (manufactured by Ihara Chemical Industry Co., Ltd., trade name: Cuamine MT) was used as the crosslinking agent, and the amount of adipic acid added was changed to 0.8 g. .

"Test method"
-Pot life A liquid V and a liquid B are mixed, and the viscosity of the liquid mixture with respect to the elapsed time after 60 seconds of stirring is completed using a B-type viscometer (rotor No. 3, rotation speed 12 rpm) in a normal temperature environment. The time when the viscosity was 4000 mPa · s was taken as the pot life.
・ Demolding time When the mixed liquid of liquid A and liquid B is poured into a sheet-shaped mold (split mold), and the mold is disassembled after crosslinking at a crosslinking temperature of 110 ° C. for 45 minutes or 60 minutes, and the sheet is taken out. Furthermore, the time for demolding without cracking or tearing in the sheet was defined as the demolding time.

-Hardness Six polyurethane sheets with a thickness of 2 mm obtained in Examples and Comparative Examples were stacked to a thickness of 12 mm, and the hardness (JIS-A) was measured with Type A according to JIS-K7312. The measurement was performed at an arbitrary five locations on the polyurethane sheet under an environment of a temperature of 23 ° C. and a humidity of 50% RH, and indicated by an arithmetic average value of each measured value.
・ M300, TB, EB (tensile test)
Samples (No. 3 dumbbell shape) were prepared from the polyurethane sheets obtained in the examples and comparative examples, and according to JIS-K7312, the 300% modulus (M300), tensile breaking strength (TB), and breaking elongation (EB) were obtained. It was measured. The measurement was performed on three samples in an environment of a temperature of 23 ° C. and a humidity of 50% RH, and indicated by an arithmetic average value of each measurement value.
・ TR-B (Tear test)
A sample (angle shape without cut) was prepared from the polyurethane sheet, and the tear strength (TR-B) was measured according to JIS-K7312. The measurement was performed on three samples in an environment of a temperature of 23 ° C. and a humidity of 50% RH, and the arithmetic average value of each measurement value was shown.
The measurement results are shown in Tables 1 and 2 below.

The polyurethane compositions of the present invention described in Examples 1 to 4 have pot life and demolding time equivalent to those of polyurethane compositions using MOCA as the curing agent described in Comparative Example 5, and are easy to handle. It was excellent and it was confirmed that molding was possible under the same molding conditions as the composition using MOCA. From Examples 2-4, when the ratio of CDAB was increased as a hardening | curing agent, it has confirmed that a pot life could be lengthened, without demolding time changing. Moreover, from Examples 1 and 2, it was confirmed that the pot life can be adjusted by the blending amount of the dicarboxylic acid compound.
The polyurethane molded product obtained from the polyurethane composition of the present invention described in Examples 1 to 4 has the same physical properties as the polyurethane molded product using the MOCA described in Comparative Example 5 as a curing agent. It was confirmed that the used compact could be replaced.

  Comparative Examples 1 and 2 having an amine ratio of less than 30/70 were generally inferior in altitude and breaking strength, and could not obtain the same physical properties as molded articles using MOCA. Comparative Examples 3 and 4 having an amine ratio of greater than 90/10 were able to obtain the same physical properties as the molded product using MOCA, but the molding time was long and the molding conditions were the same as those of the composition using MOCA. Molding with was not possible.

1. 1. Toothed belt 2. Belt teeth Core wire

Claims (6)

A urethane prepolymer comprising a polyether polyol and tolylene diisocyanate;
A polyurethane composition comprising only two amine-based curing agents, 2-methylpropyl 3,5-diamino-4-chlorobenzoate and dimethylthiotoluenediamine, as a curing agent.   The molar ratio of amino groups of the 2-methylpropyl 3,5-diamino-4-chlorobenzoate and the dimethylthiotoluenediamine is in the range of 30/70 or more and 90/10 or less. The polyurethane composition described in 1. An amino group (—NH ₂ ) of the curing agent;
3. The polyurethane according to claim 1, wherein the urethane prepolymer has a molar ratio (—NH ₂ / —NCO) to an isocyanate group (—NCO) of 0.8 or more and 0.98 or less. Composition.   The polyurethane composition according to claim 1, comprising a dicarboxylic acid compound.   A polyurethane molded product obtained by thermosetting the polyurethane composition according to claim 1.   A power transmission belt comprising the polyurethane molded body according to claim 5 as a belt body.

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