JP2002293866A - Polyurethane resin composition and polyurethane-based belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane resin composition for a curing reaction not to be inhibited, when blending a lubricant having a hydroxyl group in a system of a urethane prepolymer and an amine-based curing agent. SOLUTION: The polyurethane resin composition is produced by blending the urethane prepolymer, the amine-based curing agent, the lubricant having the hydroxyl group, and an organic carboxylic acid compound. A curing reaction of the urethane prepolymer and the amine-based curing agent can be promoted by a catalytic action of the organic carboxylic acid compound, and can be prevented from being disturbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane resin composition for a belt and a polyurethane belt formed from the polyurethane resin composition.

[0002]

2. Description of the Related Art V-belts and toothed belts have been conventionally provided as belts used for power transmission and the like, but there is a polyurethane belt using a polyurethane resin having a higher strength than rubber as a material of the belt. .

[0003] In such a polyurethane belt, attempts have been made to reduce the friction coefficient of the surface by blending a lubricant with the polyurethane resin in order to reduce noise generated during running. Conventionally, lard or salad oil has been generally used as this lubricant. However, in the case of a polyurethane belt containing lard, the lard emerges on the surface of the belt and solidifies in white, the belt appearance becomes very poor, and the effect of reducing noise during running is not sufficient. Also, when salad oil is used, there is a problem that bleed occurs and the wear resistance of the belt is inferior.

[0004] Therefore, it has been desired to develop a polyurethane resin composition using a lubricant having no problems such as lard or salad oil, and one proposal has been proposed in Japanese Patent Application Laid-Open No. 11-51212. This is a compound in which a stearic acid-based or oleic acid-based ester having a hydroxyl group is compounded as a lubricant in a urethane prepolymer, so that the lubricant does not bleed and scatter, thereby reducing the noise generation effect and abrasion. The effect of reduction can be obtained over a long period of time.

[0005]

However, the present inventors have studied the lubricant proposed in Japanese Patent Application Laid-Open No. 11-51212, and as a result, it has been found that a system in which an amine curing agent is blended with a urethane prepolymer is used. It has been found that when a lubricant is added, the lubricant reacts with the urethane prepolymer and inhibits the reaction between the urethane prepolymer and the amine-based curing agent, thereby making it impossible to increase the molecular weight.

That is, the basic reaction between the urethane prepolymer and the amine-based curing agent is as shown in Chemical Formula 1, wherein the terminal NCO of the urethane prepolymer and the terminal NH ₂ of the amine-based curing agent are urea-bonded. Further, the reaction is carried out by making the reactive groups at both ends further urea-bonded to increase the molecular weight.

[0007]

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[0008] Since the molar ratio of NCO / NH ₂ usually exceeds 1, excess NCO in the reaction of the chemical formula 1 replaces the urea group or urethane group of the high molecular weight product obtained in the reaction of the chemical formula 1. Attacks to form a burette group or an allophanate group as shown in “Chemical formula 2”, and three-dimensionally crosslink.

[0009]

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On the other hand, when the lubricant proposed in JP-A-11-51122 is present, the hydroxyl group of the lubricant reacts with the NCO of the urethane prepolymer, as shown in “Chem. It is considered that the progress of the reaction for increasing the molecular weight is inhibited (the reaction rate is generally NH ₂
>> OH, but the result of the elastic torque measurement test using a curast meter suggests that the reaction is inhibited).

[0011]

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Therefore, as a result of not being able to obtain a high-molecular-weight polyurethane cured product, the hardness of the cured product decreases,
There is a problem that abrasion resistance may be reduced.

The present invention has been made in view of the above points, and when a lubricant having a hydroxyl group is added to a system of a urethane prepolymer and an amine-based curing agent, a cured product having high hardness and excellent abrasion resistance is obtained. An object of the present invention is to provide a polyurethane resin composition which can be obtained, and an object of the present invention is to provide a polyurethane belt in which generation of noise and wear are reduced.

[0014]

The polyurethane resin composition according to the first aspect of the present invention is characterized by comprising a urethane prepolymer, an amine-based curing agent, a lubricant having a hydroxyl group, and an organic carboxylic acid compound. It is assumed that.

The invention of claim 2 is characterized in that, in claim 1, the lubricant having a hydroxyl group is selected from a fatty acid derivative having a hydroxyl group and an alkyl ether having a hydroxyl group.

According to a third aspect of the present invention, in the first or second aspect, the amine-based curing agent is 3,3'-dichloro-4,
It is 4'-diaminodiphenylmethane.

Further, the invention according to claim 4 is the method according to any one of claims 1 to 3, wherein the organic carboxylic acid is azelaic acid,
It is characterized by being selected from oleic acid and adipic acid.

A polyurethane belt according to a fifth aspect of the present invention is characterized by being formed by molding the polyurethane resin composition according to any one of the first to fourth aspects.

According to a sixth aspect of the present invention, in the fifth aspect, the lubricant is dispersed with at least a part thereof bonded to the urethane polymer.

[0020]

Embodiments of the present invention will be described below.

The polyurethane cured product can be obtained by casting a liquid polyurethane resin composition and heating and curing it. Generally, a molding method includes a polyol, a catalyst,
A one-shot method in which a premix solution containing a chain extender, a pigment, and the like, and a solution containing an isocyanate component are mixed, and the mixture is cast and cured. There is a prepolymer method in which a prepolymer in which a part is modified with a polyol is used, a catalyst is added thereto, and the mixture is cast and cured. In the present invention, a prepolymer method is employed.

As the prepolymer, those conventionally provided can be used without any particular limitation. As the isocyanate, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and the like are preferably used. Polytetramethylene ether glycol (PTM) is used as a polyol to obtain a molded article having excellent moisture resistance and water resistance, as well as tough physical properties and low hysteresis loss.
G) can be suitably used.

In the present invention, the amine curing agent is not particularly limited, but includes 1,4-phenylenediamine, 2,6-diaminotoluene, 1,5-naphthalenediamine, 4,4'-diamino Diphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 3,3'-dimethyl-4,4 '
-Diaminodiphenylmethane, 1-methyl-3,5-bis (methylthio) -2,6-diaminobenzene, 1-methyl-3,5'-diethyl-2,6-diaminobenzene, 4,4'-methylene-bis -(3-chloro-2,6
-Diethylaniline), 4,4'-methylene-bis-
(Ortho-chloroaniline), 4,4'-methylene-bis- (2,3-dichloroaniline), trimethyleneglycol-di-para-aminobenzoate, 4,4'-methylene-bis- (2, 6-diethylaniline), 4,
4'-methylene-bis- (2,6-diisopropylaniline), 4,4'-methylene-bis- (2-methyl-6
-Diisopropylaniline), 4,4'-diaminodiphenylsulfone, and the like, and primary amine, secondary amine, and tertiary amine amine compounds. The compounding amount of the amine-based curing agent is preferably such that the α value (NH ₂ / NCO), which is the ratio of the number of moles of NH ₂ in the amine-based curing agent to the number of moles of NCO in the isocyanate, is close to 1, It is preferable to set so as to be in the range of 0.90 to 1.10. Generally, when the α value is around 0.95, the physical properties of the cured product are the best, and when the α value is out of the above range, the physical properties of the cured product tend to decrease.

In the present invention, examples of the lubricant having a hydroxyl group (OH group) include fatty acid derivatives having an OH group, for example, stearic acid derivatives and oleic acid derivatives having an OH group, and more specifically, esters containing stearic acid as an acid component. And esters containing oleic acid as an acid component. Specific examples include polyoxyethylene sorbitan monostearate and polyethylene glycol monostearate. Examples of the lubricant having a hydroxyl group (OH group) include an alkyl ether having an OH group. Specific examples include polyoxyethylene stearyl ether. In addition to using these alone,
Two or more of them can be used in combination.

The amount of the OH group-containing lubricant is 0.5 to 10 parts by weight based on 100 parts by weight of the urethane prepolymer.
It is preferable to set in the range of parts by mass. If the amount is less than 0.5 parts by mass, it is difficult to sufficiently obtain the effect of improving lubricity by adding a lubricant. If the compounding amount exceeds 10 parts by mass, the inhibition of the reaction of increasing the molecular weight of urethane by the lubricant having an OH group becomes large, and the polyurethane belt may have adverse effects such as a decrease in hardness and a decrease in abrasion resistance.

In the present invention, examples of the organic carboxylic acid compound include aliphatic carboxylic acids such as azelaic acid, oleic acid, sebacic acid and adipic acid, and aromatic carboxylic acids such as benzoic acid and toluic acid. Among these, azelaic acid, oleic acid and adipic acid are more preferred. These may be used alone or in combination of two or more. The compounding amount of the organic carboxylic acid compound is 0.1 to 100 parts by mass of the prepolymer.
The range is preferably from 0.01 to 10.0 parts by mass, more preferably from 0.01 to 3.0 parts by mass. When the compounding amount of the organic carboxylic acid compound is less than 0.01 part by mass, it is difficult to sufficiently obtain the reaction promoting effect, and when it exceeds 10.0 parts by mass, the hardness adjustment becomes difficult. May occur.

In addition to the above-mentioned components, a plasticizer, a pigment, an antifoaming agent, a filler, a stabilizer and the like can be blended as additives, and the above-mentioned lubricant having an OH group as a lubricant In addition, a lubricant having no OH group can be blended. As a plasticizer, dioctyl phthalate (DO)
P), dibutyl phthalate (DBP), dioctyl adipate (DOA), tricresyl phosphate (TCP), chlorinated paraffin, dialkyl phthalate, and the like can be used.

The polyurethane resin composition according to the present invention is obtained by blending the urethane prepolymer, amine curing agent, hydroxyl group-containing lubricant, organic carboxylic acid compound, and, if necessary, various additives. Is what you can do.

Here, the polyurethane resin composition comprises a liquid A prepared by mixing an antifoaming agent and a plasticizer with a urethane prepolymer, a liquid B prepared by mixing an amine curing agent and an organic carboxylic acid compound, and an OH group. The liquid A, the liquid B, and the liquid C can be mixed at the time of preparing from the liquid C containing the lubricant and molding the polyurethane to cure the polyurethane. Solution A, Solution B, and Solution C are mixed simultaneously. In addition, Solution B and Solution C are mixed first, and Solution A is further mixed with the mixture to cure the polyurethane. You may.

In curing the polyurethane as described above, the organic carboxylic acid compound acts as an acid catalyst,
By working to promote the reaction of the NH ₂ group of the amine-based curing agent, the reaction between the urethane prepolymer and the amine-based curing agent is promoted, and the reaction for increasing the molecular weight as described in the above “Chemical Formula 1” is performed.
Therefore, it is possible to prevent the reaction of the urethane prepolymer and the amine-based curing agent with the OH group of the lubricant to increase the molecular weight by inhibiting the reaction with the organic carboxylic acid compound, The hardness of the cured polyurethane material and the abrasion resistance do not decrease.

After the reaction for increasing the molecular weight of the compound (1), the surplus NCO group reacts with the urea group or the urethane group as in the compound (2) to form a three-dimensional crosslink. Part of this surplus NCO group reacts with the OH group of the lubricant as shown in Chemical formula 3, and part of the lubricant dispersed in the urethane cured product becomes bound to urethane molecules. Bleeding on the surface of the substrate is reliably prevented. When a part of the lubricant undergoes the reaction of "Chemical Formula 3", the three-dimensional cross-linking of "Chemical Formula 2" slightly decreases, but the amount is small. Also acts as an intermolecular interaction, and hardly any deterioration in the physical properties of the cured product is observed.

Then, a belt such as a V-belt or a toothed belt can be manufactured using the polyurethane resin composition obtained as described above. This belt is formed by molding a belt main body from a cured polyurethane material and embedding a cord in the belt main body in the longitudinal direction of the belt. In this polyurethane belt, a lubricant of a fatty acid derivative having a hydroxyl group or an alkyl ether enhances the smoothness of the belt surface, and can reduce noise during running and reduce abrasion. .

[0033]

The present invention will be described below in detail with reference to examples.

Example 1 A polyurethane resin composition having the composition shown in Table 1 was obtained. Here, in Table 1, PTMG-TDI prepolymer (UNIROYA) was used as the prepolymer.
L, trade name "Adiprene L-100"), MOCA as an amine-based curing agent, polyoxyethylene sorbitan monostearate (trade name, "Reodol TW-S106", manufactured by Kao Corporation) as a lubricant, and azelaic acid as an organic carboxylic acid compound , DOP as a plasticizer and a silicon compound as an antifoaming agent.

(Comparative Examples 1 to 3) The polyurethane resin composition of Comparative Example 1 was prepared using the composition of Table 1 without using an organic carboxylic acid compound, and the polyurethane resin composition of Comparative Example 2 was prepared using the formulation of Table 1 without using a lubricant. Then, a polyurethane resin composition of Comparative Example 3 was obtained with the composition shown in Table 1 without using a lubricant and an organic carboxylic acid compound, respectively.

[0036]

[Table 1]

The curing properties of the polyurethane resin compositions of Example 1 and Comparative Examples 1 to 3 were evaluated by measuring the elastic torque using a curast meter (vulcanizing tester). That is, according to the composition shown in Table 1, first, a urethane prepolymer, an antifoaming agent, and a plasticizer are stirred and mixed at room temperature. Liquid and lubricant at 60 ° C
Solution C was prepared by mixing at a temperature of 120 ° C., and then this solution and Solution A were mixed by stirring with a mixer, and then charged into a resin die and measured at a measuring temperature (curing temperature). Elastic torque was measured with a curastometer under the conditions of (temperature) 110 ° C and amplitude width (1/4) ° to obtain a curing curve. The result is shown in FIG.

As can be seen from the curing curve of FIG. 1, in the case of Comparative Example 1 in which the lubricant was blended and the organic carboxylic acid was not blended, the curing hardly proceeded even after 600 minutes, and the lubricant having an OH group was replaced with urethane. It is known that it inhibits the curing reaction. On the other hand, in the case of Example 1 in which the lubricant was blended and the organic carboxylic acid was blended, the curing proceeded normally and the cured product became an elastic body. It is confirmed that the urethane curing reaction normally proceeds by adding the acid compound.

(Examples 2 and 3) The polyurethane resin composition of Example 2 was prepared in the same composition as in Example 1 except that polyoxyethylene stearyl ether (trade name "Emulgen 320P" manufactured by Kao Corporation) was used as a lubricant. Was used in the same manner as in Example 1 except that polyethylene glycol monostearate (trade name “Emanon 3199” manufactured by Kao Corporation) was used as a lubricant to obtain a polyurethane resin composition of Example 3 respectively.

Comparative Examples 4 and 5 The same procedure as in Example 1 was repeated except that lard was used as a lubricant, and the polyurethane resin composition of Comparative Example 4 was replaced with salad oil as a lubricant. A polyurethane resin composition of Comparative Example 5 was obtained with the same composition as in Example 1 (both did not contain an organic carboxylic acid compound).

As described above, Examples 1-3 and Comparative Examples 4,
By molding the polyurethane resin composition obtained in 5, the polyurethane V-belt (Polymax 5M775)
Belt). And this belt is diameter 26.5
mm driven pulley and a 50.5 mm diameter driven pulley, misalignment 1 °, rotation speed 3600 rpm
m, initial shaft load 118N (12kgf), load 0.26
A running test was performed for 500 hours under the condition of kW, and the sound generated during belt running and the amount of belt wear were measured. Table 2 shows the results.

[0042]

[Table 2]

As can be seen from Table 2, in Examples 1 to 3 in which a lubricant composed of a fatty acid derivative having an OH group or an alkyl ether was blended, there was no sound during traveling, the amount of wear was small, and the durability was low. It was expensive. On the other hand, in Comparative Example 4 using lard, the pronunciation could not be reduced, and in Comparative Example 5 using salad oil, abrasion occurred significantly.

Further, the above Examples 1 to 3 and Comparative Examples 4,
A V-belt made of the polyurethane resin composition of No. 5 was subjected to a running test to measure a slip ratio. The running test was performed with a diameter of 2
A belt is suspended between a 6.5 mm drive pulley and a 50.5 mm diameter driven pulley. The rotation speed is 3600 rpm, the initial shaft load is 118 N (12 kgf), and the load is 0.05 kW.
From 0.6 to 0.6 kW. The results are shown in FIG. The slip ratio of a belt made of a polyurethane resin composition containing no lubricant was measured in the same manner, and the result was shown as "none".

As can be seen from Table 2, in Examples 1 to 3, the slip ratio was higher than that in the case where no lubricant was added, and the friction coefficient of the belt surface was reduced due to the lubricating effect of the lubricant. It is confirmed that.

Further, the V-belts made of the polyurethane resin compositions of Examples 1 to 3 and Comparative Examples 4 and 5 were stored at room temperature for one year, respectively, and visually inspected for the bleeding of the lubricant component on the belt surface. Observation revealed that Example 1
In Nos. 3 to 3, no bleeding of the lubricant was observed, but in Comparative Examples 4 and 5, the lubricant bleed and bleed out. As described above, since the bleed control effect of the belt of each example is maintained for a long period of time, it is considered that the lubricant is bonded to the urethane polymer.

(Example 4, Comparative Example 6) A polyurethane resin composition having the composition shown in Table 3 was obtained. Here, each component in Table 3 was the same as that in Table 1 except that polyethylene glycol monostearate (trade name “Emanon 3199” manufactured by Kao Corporation) was used as a lubricant.

[0048]

[Table 3]

By molding the polyurethane resin compositions obtained in Example 4 and Comparative Example 6, a toothed belt (timing belt) having a width of 6.0 mm, a belt length of 345 mm, and a tooth shape S3M was produced. This belt is suspended between a drive pulley having 22 teeth and a driven pulley having 40 teeth, and has a rotation speed of 3600 rpm and an initial tension of 59 N (6.0 kg).
f), the belt was run under the conditions of a cutoff standard of 300 hours, and a belt durability test was performed in a room temperature atmosphere. As a result, in the case of Comparative Example 6, tooth chipping occurred in 124 hours.
No abnormalities were observed after running for 300 hours.
Therefore, the surface friction coefficient of the belt is reduced by the addition of the lubricant, and the interference between the engagement of the belt and the pulley is reduced,
It is confirmed that the belt durability has been improved.

Next, the cured products of the polyurethane resin compositions obtained in Example 1 and Comparative Example 2 were used as samples, and each was subjected to acetone extraction for 8 hours by a Soxhlet extraction method using each of them as an acetone solvent. The results are shown in Example 1.
The measured value of the amount of acetone extracted was 27.3%, and the measured value of the amount of acetone extracted in Comparative Example 2 was 21.9%.

When the acetone extract was qualitatively determined by infrared spectrum, a chart as shown in FIG. 3 was obtained in Example 1 and a chart as in FIG. 4 was obtained in Comparative Example 4. Example 1, none of the comparative example 2, C = O stretching vibration of the ester was observed at 1727 cm ^-1, 1600 cm ^-1,
At 1579 cm ^-1 , absorption due to aromatics was observed.
At 274 cm ^-1 , CO stretching vibration is observed, and 1072c
m- ¹ shows C-OC stretching vibration. Like this one
C = O stretching vibration in 727cm ^-1, the 1072cm ^-1 C-
Judging from the OC stretching vibration and other peak characteristics, the main component of the acetone extract is considered to be the plasticizer DOP.

Here, of the composition of Comparative Example 2, it is considered that the extractables with acetone are 0.5 parts by mass of the organic carboxylic acid compound, 30 parts by mass of the plasticizer, and 0.2 parts by mass of the defoamer.
30.7 parts by mass of parts by mass. Therefore, the calculated value of the amount of acetone extracted was 30.7 parts by mass (30.7 / 142.7 × 100 =) with respect to 142.7 parts by mass of the total amount of the composition.
21.5%, which is almost the same as the above measured value of 21.9%.

On the other hand, in Example 1, 27.3% of the actually measured value was higher than the calculated value, and the amount of acetone extracted was large. As seen in the chart of FIG. 3, there is a peak at 3349 cm ⁻¹ ,
This is presumed to be a peak due to the OH group, and it is considered that the lubricant was extracted with acetone. Assuming that all the lubricant was extracted with acetone, the calculated value of the amount of acetone extracted was 3 to 147.7 parts by mass of the total amount of the composition.
5.7 parts by mass of (35.7 / 147.7 × 100 =) 2
4.2%, 27.3% of the measured value exceeds the calculated value. Considering that a high molecular weight polymer is not extracted by acetone extraction, it is considered that a low molecular weight polymer was extracted from the extract of Example 1 in addition to the above-mentioned compounding agents such as a plasticizer and an antifoaming agent. . Further, as described above, since the bleed control effect of the belt of the example is maintained for a long period of time, it is presumed that the lubricant is bonded to the urethane polymer in the example. From these results, most of the urethane polymer of Example 1 has a high molecular weight, but the lubricant having an OH group partially undergoes the reaction of “Chemical Formula 3” to produce a low molecular weight urethane polymer. It is inferred that the measured value shows a higher value than the calculated value because the low molecular weight urethane polymer is extracted with acetone.

[0054]

As described above, the polyurethane resin composition according to claim 1 of the present invention contains a urethane prepolymer, an amine-based curing agent, a lubricant having a hydroxyl group, and an organic carboxylic acid compound. The curing reaction between the urethane prepolymer and the amine-based curing agent can be promoted by the catalytic action of the organic carboxylic acid compound, and the curing reaction between the urethane prepolymer and the amine-based curing agent is inhibited by the hydroxyl groups of the lubricant. That can be prevented.

According to the second aspect of the present invention, as the lubricant having a hydroxyl group, a lubricant selected from a fatty acid derivative having a hydroxyl group and an alkyl ether having a hydroxyl group is used, so that these lubricants bleed or scatter. Therefore, the effect of imparting lubrication can be maintained for a long period of time.

According to the third aspect of the present invention, 3,3'-dichloro-4,4'-diaminodiphenylmethane is used as an amine-based curing agent, so that the urethane prepolymer is catalyzed by an organic carboxylic acid compound. It can greatly accelerate the curing reaction.

According to the fourth aspect of the present invention, since the organic carboxylic acid is selected from azelaic acid, oleic acid and adipic acid, the curing reaction between the urethane prepolymer and the amine curing agent is greatly accelerated. Is what you can do.

The polyurethane belt according to a fifth aspect of the present invention is formed by molding the polyurethane resin composition according to any one of the first to fourth aspects. It has high lubricity, can reduce sound generation during traveling, and can reduce wear.

According to the invention of claim 6, since the lubricant is dispersed at least partially in a state of being bonded to the urethane polymer, it is possible to prevent the lubricant from bleeding out, to reduce noise due to the dispersion of the lubricant and to reduce noise. The effect of improving the wear resistance can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a curing time and an elastic torque.

FIG. 2 is a graph showing a relationship between a belt load and a slip ratio.

FIG. 3 is a chart of an infrared spectrum analysis of the acetone extract of Example 1.

FIG. 4 is a chart of infrared spectrum analysis of an acetone extract of Comparative Example 2.

Continued on front page F-term (reference) 4J034 BA05 CA15 CA17 CB03 CB07 CC03 CC08 CC10 CC12 CC13 CC61 CC67 CD04 CD06 CD08 CD13 DA01 DB01 DG03 DG14 HA01 HA07 HC12 HC61 HC64 HC67 HC71 JA42 KA01 KB04 KD02 KE02 QB12 RA11

Claims (6)

[Claims] 1. A polyurethane resin composition comprising a urethane prepolymer, an amine-based curing agent, a lubricant having a hydroxyl group, and an organic carboxylic acid compound. 2. The polyurethane resin composition according to claim 1, wherein the lubricant having a hydroxyl group is selected from a fatty acid derivative having a hydroxyl group and an alkyl ether having a hydroxyl group. 3. The polyurethane resin composition according to claim 1, wherein the amine curing agent is 3,3'-dichloro-4,4'-diaminodiphenylmethane. 4. The polyurethane resin composition according to claim 1, wherein the organic carboxylic acid is selected from azelaic acid, oleic acid, and adipic acid. 5. A polyurethane belt formed by molding the polyurethane resin composition according to claim 1. Description: 6. The polyurethane belt according to claim 5, wherein the lubricant is dispersed with at least a part thereof bonded to the urethane polymer.