JP6308380B2 - Urethane elastomer molded product - Google Patents

Description

  The present invention relates to a urethane elastomer molded article having excellent dynamic characteristics.

  Urethane elastomer molded products are widely used as members of tires, steel rolls, papermaking rolls, snow plows and the like because of their excellent dynamic characteristics as compared with other rubber materials.

  Examples of the urethane elastomer molded article include those obtained by using a urethane composition containing a urethane prepolymer having an isocyanate group and 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA). (For example, see Patent Document 1).

  However, the urethane elastomer molded product has a problem that it deteriorates as it is used, particularly when used for a roll or the like.

JP 2013-166858 A

  The problem to be solved by the present invention is to provide a urethane elastomer molded article excellent in storage elastic modulus and creep property.

  The present invention includes a main agent (i) containing a urethane prepolymer (A) obtained by reacting a polyol (a1) and a polyisocyanate (a2), a curing agent (ii) containing a polyamine compound (B), an average The present invention provides a urethane elastomer molded article obtained by using a urethane composition containing refined cellulose (iii) having a particle diameter of 10 μm or less.

  The urethane elastomer molded article of the present invention is excellent in storage elastic modulus and creep property, has a long pot life, and is excellent in workability. Therefore, the urethane elastomer molded product of the present invention can be suitably used as a member for tires, steel rolls, papermaking rolls, snow plows and the like.

  As said polyol (a1), polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, polybutadiene polyol, polyacryl polyol, dimer diol etc. can be used, for example. These polyols may be used alone or in combination of two or more. In addition, when using 2 or more types together as said polyol (a1), for example, the single thing is used as a polyol at the time of refining cellulose mentioned below, and it makes it react with polyisocyanate (a2) mentioned later after refining. In this case, other polyols may be mixed and used. Among these, it is preferable to use a polyether polyol because the ease of micronization of cellulose, the dispersion stability of micronized cellulose, the storage elastic modulus, and the creep property can be further improved.

  Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethylene polypropylene glycol. Among these, it is preferable to use polytetramethylene glycol from the viewpoint that the ease of micronization of cellulose, the dispersion stability of micronized cellulose, the storage elastic modulus, and the creep property can be further improved.

  The number average molecular weight of the polyol (a1) is preferably in the range of 500 to 5,000, more preferably in the range of 700 to 3,000, from the viewpoint of storage modulus and creep properties. In addition, the number average molecular weight of the said 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 polyisocyanate (a2) 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 burette-modified form. Diphenylmethane diisocyanate derivatives such as diphenylmethane diisocyanate, toluene diisocyanate, tolidine diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylene diisocyanate; Cycloaliphatic such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate Polyisocyanate; 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 toluene diisocyanate is more preferably used, from the viewpoint that the dispersion stability, storage elastic modulus, and creep property of fine cellulose can be further improved.

  The reaction between the polyol (a1) and the polyisocyanate (a2) is preferably, for example, a molar ratio (NCO / OH) between the hydroxyl group of the polyol (a1) and the isocyanate group of the polyisocyanate (a2). Can be carried out in the range of 1.01 to 30, more preferably in the range of 2 to 20, and still more preferably in the range of 4 to 15.

  The urethane prepolymer (A) obtained by the above method has an isocyanate group, and the isocyanate group equivalent (hereinafter abbreviated as “NCO equivalent”) is from the viewpoint of storage elastic modulus and creep property. 150-2,000 g / eq. It is preferable that it is the range of 500-1,500 g / eq. Is more preferable, 800-1200 g / eq. The range of is more preferable.

  As content of the said urethane prepolymer (A) in the said main ingredient (i), it is preferable that it is 50 mass% or more, and it is more preferable that it is the range of 70-100 mass%.

  Examples of the polyamine compound (B) include aliphatic diamines such as ethylenediamine, 1,3-propanediamine, 1,3- or 1,4-butanediamine, and 1,6-hexamethylenediamine; Such as diamine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, 2,5 (2,6) -bis (aminomethyl) bicyclo [2.2.1] heptane, 1,3-bis (aminomethyl) cyclohexane Cycloaliphatic diamine; tolylenediamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-bis (methylthio) ) Aromatic diamines such as -2,4-toluenediamine; hydrazine and the like can be used. These polyamine compounds may be used alone or in combination of two or more. Among these, aromatic diamines are preferably used from the viewpoint of workability, storage elastic modulus, and creep properties, and 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) is more preferably used.

  The total mass of the polyamine compound (B) in the curing agent (ii) is preferably 50% by mass or more, and more preferably in the range of 70 to 100% by mass.

  The refined cellulose (iii) having an average particle size of 10 μm or less is an essential component for obtaining a urethane elastomer molded article excellent in storage elastic modulus and creep property. As a method for obtaining the refined cellulose, a method of obtaining the refined cellulose by refining cellulose in the polyol (a1) can be preferably used. According to this method, since the refined cellulose is present in the polyol (aa1), the subsequent urethanization reaction can be easily performed.

  Examples of the cellulose that is a raw material of the fine cellulose include, for example, regenerated cellulose fibers such as pulp, cotton, paper, rayon, cupra, polynosic acetate, etc .; cellulose derived from animals such as bacteria-produced cellulose and sea squirt; regenerated cellulose fibers and animals Those obtained by chemically modifying the surface of derived cellulose; cellulose fine powder and the like can be used.

  As said pulp, wood pulp, non-wood pulp, etc. can be used, for example. As the wood pulp, mechanical pulp and chemical pulp can be used, and it is preferable to use chemical pulp from the viewpoint of low lignin content. In addition, as the chemical pulp, sulfide pulp, kraft pulp, alkaline pulp or the like can be used. As the non-wood pulp, straw, bagasse, kenaf, bamboo, straw, straw, flax and the like can be used.

  The cotton is a plant mainly used for clothing fibers, and cotton, cotton fibers, cotton and the like can be used.

  The paper is obtained by removing fibers from pulp, and used paper such as newspaper, waste milk pack, copied paper, and the like can be used.

  The average particle size of the cellulose fine powder is preferably in the range of 20 to 50 μm from the viewpoint that it is easy to produce refined cellulose having an average particle size of 10 μm or less and the storage elastic modulus and creep properties can be further improved. The range of 22 to 46 μm is more preferable, and the range of 22 to 43 μm is still more preferable. In addition, the average particle diameter of the said cellulose fine powder shows the value (micrometer) of D50 measured using Shimadzu Corporation laser diffraction type particle size distribution analyzer "SALD-7000".

  As the cellulose fine powder, for example, “KC Flock” (manufactured by Nippon Paper Chemicals Co., Ltd.), “Theoras” (manufactured by Asahi Kasei Chemicals Co., Ltd.), “Avicel” (manufactured by FMC), etc. can be obtained as commercial products. .

  Examples of the method for refining the cellulose in the polyol (a1) include a method in which the cellulose is added to the polyol (a1) and mechanically giving a cutting force. Examples of the method for applying the shearing force include an extruder such as a bead mill, an ultrasonic homogenizer, a single screw extruder, a twin screw extruder; a Banbury mixer, a grinder, a pressure kneader, a kneader such as a two roll. A method is mentioned. Among these, it is preferable to use a pressure kneader from the viewpoint of obtaining a stable shear force in the polyol (a1).

  The rotation speed when using the pressure kneader is preferably 10 rpm or more, more preferably 30 to 100 rpm, and the defibration time is preferably about 60 to 600 minutes.

  By the above-described refinement method, the cellulose is fibrillated into refined cellulose having an average particle size of 10 μm or less, preferably 0.01 to 10 μm, and becomes cellulose nanofiber (CNF). When the average particle diameter of the fine cellulose does not become 10 μm or less, there is a problem that desired storage elastic modulus and creep property cannot be obtained. In addition, the average particle diameter of the said refined cellulose shows the value (micrometer) of D50 measured using Shimadzu Corporation laser diffraction type particle size distribution measuring apparatus "SALD-7000".

  Further, in the above-mentioned miniaturization method, for example, in observation at 10,000 times of a scanning electron microscope, the range from 100 nm to 1,000,000 nm in the major axis direction and the range from 5 nm to 1,000 nm in the minor axis direction. The cellulose can be refined to obtain cellulose nanofiber (CNF).

  As content of the said refined cellulose (iii), it is preferable that it is the range of 1-10 mass% in a urethane elastomer molded article from the point which can improve a storage elastic modulus and creep property further, and is 5-9 mass%. The range of is more preferable.

  The urethane elastomer molded article of the present invention comprises a main agent (i) containing the urethane prepolymer (A), a curing agent (ii) containing the polyamine compound (B), and a refined cellulose having an average particle size of 10 μm or less. Although it is obtained using the urethane composition which contains (iii) as an essential component, you may contain another additive as needed in the said urethane composition.

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

  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 respectively put into each tank of a mixed casting machine, and the main agent (i) is preferably heated in the range of 40 to 130 ° C. And the said hardening | curing agent (ii) is heated in the range of preferably 40-130 degreeC, and each is mixed with a mixing caster.

  As a mixing ratio of the main agent (i) and the curing agent (ii), from the viewpoint of storage elastic modulus and creep property, the urethane prepolymer (A) in the main agent (i) and the curing agent (ii) The mass ratio [(A) / (B)] to the polyamine compound (B) is preferably in the range of 60/40 to 90/10, and preferably in the range of 70/30 to 85/15. More preferred.

  Next, the urethane composition is heated and held in a state where it is injected into the mold and cured, and after-curing is preferably performed under conditions of 100 to 120 ° C. and 8 to 17 hours, a urethane elastomer molded product can be obtained.

  The hardness of the urethane elastomer molded article obtained by the above method is preferably in the range of 50 to 99 from the viewpoint of storage elastic modulus and creep property. The range of 70-97 is more preferable. In addition, the hardness of the urethane elastomer molded product is a spring hardness test in accordance with JIS K 7312-1996 (hardness test), and shows a value evaluated by type A.

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

[ Reference Example 1]
Cellulose fine powder (Nippon Paper Chemical Co., Ltd.) having 50 parts by mass of polytetramethylene glycol (number average molecular weight; 1,000) and an average particle size of 37 μm in a four-necked flask equipped with a stirrer, a thermometer and a reflux tube "W-100" manufactured by MORIMA Co., Ltd.) was mixed at 50 rpm for 540 minutes using a pressure kneader (DS1-5GHH-H) manufactured by Moriyama Co., Ltd., and the cellulose was refined to contain the refined cellulose. Polytetramethylene glycol (hereinafter abbreviated as “ CNF-containing PTMG”) was obtained. Here, when the obtained CNF-containing PTMG was observed with a scanning electron microscope (10,000 times) and the refinement state of cellulose was confirmed, cellulose nanofibers finely broken from 100 nm were present, and average particles Since the diameter was 10 μm or less, it was confirmed that a good cellulose nanofiber could be produced.
Subsequently, toluene diisocyanate (“Cosmonate T-100” manufactured by Mitsui Chemicals Polyurethane Co., Ltd., hereinafter referred to as “TDI”) was added to a 1-liter four-necked round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer. Abbreviated.) 295.5 parts by mass were charged and stirring was started. Subsequently, 939 parts by mass of polytetramethylene glycol (number average molecular weight; 1,000) and 122 parts by mass of the CNF-containing PTMG were charged in portions and mixed, reacted at 70 ° C. for 5 hours under a nitrogen stream, and an isocyanate group equivalent (hereinafter, (Abbreviated as “NCO equivalent”.) A urethane prepolymer (A-1) having 990 isocyanate groups was obtained.
Next, the urethane prepolymer (A-1) as a main agent and 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter abbreviated as “MOCA”) as a curing agent are 120 ° C. in a container. The temperature was adjusted to [Urethane prepolymer (A-1)] / [MOCA] = 100 / 12.2 and stirred and mixed to prepare a urethane composition and preheated to 110 ° C. Injected into. Thereafter, the cured product was after-cured at 110 ° C. for 16 hours to obtain a urethane elastomer molded product. The content of fine cellulose in the obtained urethane elastomer molded article was 4% by mass.

[Example 2]
Cellulose fine powder (Nippon Paper Chemical Co., Ltd.) having 50 parts by mass of polytetramethylene glycol (number average molecular weight; 1,000) and an average particle size of 37 μm in a four-necked flask equipped with a stirrer, a thermometer and a reflux tube "W-100" manufactured by MORIMA Co., Ltd.) was mixed at 50 rpm for 540 minutes using a pressure kneader (DS1-5GHH-H) manufactured by Moriyama Co., Ltd., and the cellulose was refined to contain the refined cellulose. Polytetramethylene glycol (hereinafter abbreviated as “ CNF-containing PTMG”) was obtained. Here, when the obtained CNF-containing PTMG was observed with a scanning electron microscope (10,000 times) and the refinement state of cellulose was confirmed, cellulose nanofibers finely broken from 100 nm were present, and average particles Since the diameter was 10 μm or less, it was confirmed that a good cellulose nanofiber could be produced.
Next, 295.5 parts by mass of TDI was charged into a 1 liter four-necked round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, and stirring was started. Next, 872 parts by mass of polytetramethylene glycol (number average molecular weight; 1,000) and 255 parts by mass of the CNF-containing PTMG were charged in portions and mixed, reacted at 70 ° C. for 5 hours under a nitrogen stream, and an isocyanate group equivalent (hereinafter, (Abbreviated as “NCO equivalent”.) A urethane prepolymer (A-2) having 995 isocyanate groups was obtained.
Subsequently, the said urethane prepolymer (A-2) which is a main ingredient and the MOCA which is a hardening | curing agent are temperature-controlled at 120 degreeC to a container, and [urethane prepolymer (A-2)] / [MOCA] = 100/12. A urethane composition was prepared by stirring and mixing at a mass ratio of 1 and poured into a mold preheated to 110 ° C. Thereafter, the cured product was after-cured at 110 ° C. for 16 hours to obtain a urethane elastomer molded product. The content of fine cellulose in the obtained urethane elastomer molded article was 7.4% by mass.

[Comparative Example 1]
Next, 295.5 parts by mass of TDI was charged into a 1 liter four-necked round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, and stirring was started. Subsequently, 1,000 parts by mass of polytetramethylene glycol (number average molecular weight; 1,000) were charged in portions and mixed, and the reaction was carried out at 70 ° C. for 5 hours under a nitrogen stream to obtain an isocyanate group equivalent (hereinafter referred to as “NCO equivalent”). (Abbreviated)) A urethane prepolymer (A-3) having 945 isocyanate groups was obtained.
Subsequently, the said urethane prepolymer (A-3) which is a main ingredient and MOCA which is a hardening | curing agent are temperature-controlled at 120 degreeC to a container, and [urethane prepolymer (A-3)] / [MOCA] = 100/12. The urethane composition was prepared by stirring and mixing at a mass ratio of 7, and poured into a mold preheated to 110 ° C. Thereafter, the cured product was after-cured at 110 ° C. for 16 hours to obtain a urethane elastomer molded product.

[Measurement method of elastic storage rate]
The urethane elastomer molded products obtained in Examples and Comparative Examples were cut into 50 mm × 5 mm × 2 mm to obtain test pieces. Next, this test piece was set so that the gap between the chucks of the tension jig was 38 mm, and the vibration amplitude was −25 to 25 (μm), the minimum weight amplitude was 0 (N), the preload load was 50 (N). A sinusoidal distortion with a frequency of 11 (Hz) was applied, and tan δ (loss tangent) in the range of −50 to 150 (° C.) was measured to obtain a storage elastic modulus (MPa).

[Creep property evaluation method]
A cylindrical urethane elastomer molded product was obtained instead of the cylindrical mold having a diameter of 17.8 and a height of 25 mm as the mold used in the examples and comparative examples, and used as a test piece. The test piece is subjected to static load by a flexometer constant load method; 100 (N), dynamic load; 1,100 (N), frequency: 30 (Hz), temperature: 50 (° C.), test time: 25 (min) The creep after the test was measured. When the creep was less than 6, it was evaluated as “T”, and when it was 6 or more, it was evaluated as “F”.

  It turned out that Examples 1-2 which are the urethane elastomer molded articles of this invention are excellent in an elastic storage rate and creep property.

  On the other hand, although the comparative example 1 is an aspect which does not contain refinement | purification cellulose, it turned out that a storage elastic modulus is low and a creep is large.

Claims (3)

Measured by laser diffraction method with main agent (i) containing urethane prepolymer (A) obtained by reacting polyol (a1) and polyisocyanate (a2), curing agent (ii) containing polyamine compound (B) Obtained by using a urethane composition containing a refined cellulose (iii) having a D50 of 10 μm or less and a content of the refined cellulose (iii) in the range of 5 to 9% by mass in the urethane elastomer molded article. A urethane elastomer molded product characterized by   The urethane elastomer molded article according to claim 1, wherein the refined cellulose (iii) is obtained by refining cellulose in the polyol (a1).   The urethane elastomer molded article according to claim 1, wherein the polyol (a1) is a polyether polyol.