JP2002226700A - Material for molding belt and power-transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for molding belts which contains a plasticizer having a low load to the environment, and power transmission belts having a similar or better performance than conventional power transmission belts made of urethane can be obtained therefrom. SOLUTION: In a belt-forming material used for making a urethane power- transmission belt by casting into a metal mold and by hardening reaction, a primary plasticizer consisting of a trimellitic acid alkyl ester, and a secondary plasticizer made from at least one of a citric acid ester, an acetylated monoglyceride or a polyether ester are contained by 10-20 pts.wt. in 100 pts.wt. of the prepolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt forming material and a power transmission belt having a belt body formed by a curing reaction of the material.

[0002]

2. Description of the Related Art In the fields of general industrial machines and office automation equipment, urethane transmission belts are used. Such urethane transmission belts include polyisocyanate such as tolylene diisocyanate (hereinafter referred to as “TDI”) and polytetramethylene ether glycol (hereinafter “PTI”).
MG) and a liquid prepolymer produced by synthesizing a polyol with a curing agent such as 3,3'-diaminodiphenylmethane and other compounding agents. It is manufactured by injecting into a mold and allowing it to undergo a curing reaction. Here, the compounding agent contains a plasticizer, and by including the plasticizer, the viscosity of the belt molding material becomes low, so that the castability is improved, and the rigidity of the manufactured belt is moderate. In addition, the flexibility is imparted, the cold resistance is enhanced, and the plasticizer precipitates on the belt surface, so that the contact between the belt and the pulley is smooth, and the durability of the belt is improved. . As the plasticizer, di- (2-ethylhexyl) phthalate (hereinafter referred to as "DOP") or dioctyl adipate (hereinafter referred to as "DOA"), which is widely used as a plasticizer for vinyl chloride, is most commonly used. I have.

By the way, D used as a plasticizer
OP and DOA are based on the PRTR method (Pollutant Release an
As specified in the Designated Chemical Substances in the (d Transfer Register), it can be said that these substances have a large impact on the environment and are not desirable to use.

JP-A-6-16925 discloses PTMG having a molecular weight of 200 to 10,000 and molecular weight of 200 to 100.
And a polyol having a mass ratio of PTMG / polypropylene glycol = 55/45 to 90/10 and a TDI, and having a terminal isocyanate group. It is disclosed that a urethane prepolymer having a urethane prepolymer and a crosslinking agent added to the urethane prepolymer constitute a urethane composition for forming a belt, and according to such a configuration, the viscosity of the urethane prepolymer can be appropriately reduced. Even without adding a plasticizer, problems such as entrapment of air bubbles and unfilling of the mold can be eliminated, improving the formability of the belt, and the friction of the formed belt due to bleeding of the plasticizer. It is described that the transfer function can be improved by preventing the reduction of the coefficient.

Japanese Patent Application Laid-Open No. Hei 10-31376 discloses that a prepolymer composed of paraphenylene diisocyanate and one or more of a polyester polyol, a polyether polyol and a polycarbonate polyol is mixed with an ether / ester plasticizer. A toothed belt using a polyurethane elastomer obtained by blending a curing agent and a curing agent is disclosed.According to such a configuration, it is described that the toothed belt has excellent heat resistance and excellent heat resistance and bending performance as compared with the related art. I have.

[0006]

SUMMARY OF THE INVENTION The object of the present application is to provide a DO
Belt molding that uses a plasticizer that has a lower environmental load than P and DOA, and that can manufacture a power transmission belt having performance equal to or higher than a urethane power transmission belt using DOP or DOA as a plasticizer An object of the present invention is to provide a power transmission belt in which a belt material is formed by a curing reaction of the material.

[0007]

According to the present invention, as a plasticizer for a material for forming a belt, at least one of a first plasticizer comprising an alkyl trimellitate ester, and a citrate ester, an acetylated monoglyceride, or a polyether ester is used. Are contained in the prepolymer in predetermined amounts, respectively.

Specifically, the present invention relates to a belt molding material used for producing a power transmission belt made of urethane by injecting it into a belt molding die and performing a curing reaction, comprising a polyisocyanate and a polyol. And a second plasticizer comprising at least one of citric acid ester, acetylated monoglyceride, and polyether ester. Polymer 1
It is characterized by containing 10 to 20 parts by mass with respect to 00 parts by mass.

According to the above configuration, the first and second plasticizers are not specified as specified chemical substances by the PRTR method unlike DOP and DOA, so that the power transmission belt to be formed has an environmental load. It will be low.

Further, the first plasticizer has low compatibility with the urethane prepolymer and, after curing, precipitates on the belt surface to impart surface lubricity, thereby realizing smooth contact with the pulley. It has the function of improving the life of the belt, but the first plasticizer is contained in the prepolymer to such an extent that its precipitation on the belt surface does not become excessive, while the second plasticizer has high compatibility with the prepolymer. Although it hardly changes the belt surface properties after being mixed into the belt main body after curing, it affects the rigidity of the belt, but the second plasticizer is included in the prepolymer to adjust the rigidity of the belt, As a result, an appropriate belt surface lubrication property and rigidity are secured, and the transmission belt has a performance equal to or higher than that of a urethane transmission belt using DOP or DOA as a plasticizer. It is possible to obtain.

Here, if the content of the first plasticizer is less than 10 parts by mass with respect to 100 parts by mass of the prepolymer, the amount of the plasticizer deposited on the belt surface is reduced, and the smooth contact between the belt and the pulley is achieved. Is not realized. The content of the first plasticizer is 20 per 100 parts by mass of the prepolymer.
When the amount is more than the mass part, the amount of the plasticizer deposited on the belt surface becomes excessive, resulting in poor appearance and cause the belt to slip on the pulley.

On the other hand, if the content of the second plasticizer is less than 10 parts by mass with respect to 100 parts by mass of the prepolymer, the rigidity of the belt becomes too high and the flexibility becomes poor. If the content of the second plasticizer is more than 20 parts by mass with respect to 100 parts by mass of the prepolymer, the rigidity of the belt becomes too low and heat is easily generated.

The polyisocyanate constituting the prepolymer is not particularly restricted but includes TDI, diphenylmethane diisocyanate (MDI) and the like.

The polyol constituting the prepolymer is not particularly limited, and examples thereof include PTMG,
Polyether glycol such as polypropylene ether glycol (PPG) and polyethylene adipate (PE
A), poly-ε-caprolactone glycol (PCL)
And the like.

[0015] The alkyl trimellitate is
A compound in which all three carboxyl groups of 2,4-benzenetricarboxylic acid form an ester with an alkyl alcohol, and are not particularly limited, and all carboxyl groups form an ester with the same alkyl alcohol, respectively. Or one of the three may form an ester with a different alkyl alcohol, or all may form an ester with a different alkyl alcohol. Instead of a single compound, it may be a mixed alkyl ester of trimellitic acid obtained by mixing compounds having three different ester structures. Examples of the alkyl alcohol that forms an ester with a carboxyl group include isooctyl alcohol, 2-ethylhexyl alcohol, isodecyltriethyl alcohol, and alkyl alcohols having 6 to 10 carbon atoms (C).

The citric acid ester is not particularly limited, for example, triethyl citrate (TEC),
Examples thereof include tri-n-butyl citrate (TBC), acetyl triethyl citrate, acetyl tri-n-butyl citrate (hereinafter, referred to as “ATBC”), and acetyl tri- (2-ethylhexyl) citrate.

The acetylated monoglyceride is not particularly restricted but includes, for example, glycerin diacet monolaurate, glycerin diacet monostearate and glycerin diacet monooleate.

The polyetherester is not particularly limited, and examples thereof include a polyetherester formed by using fatty acid as an acid component and polyethylene glycol having a long molecular chain as an alcohol component.

Table 1 shows specific examples used as the first and second plasticizers.

[0020]

[Table 1]

The above configuration is not limited to the belt molding material used in the prepolymer molding method, but can be applied to a belt molding material used in the pseudo prepolymer molding method.
In this case, a mixture of a pseudo prepolymer produced by synthesizing a polyisocyanate and a polyol, and a polyol of the same type or a different type as the polyol constituting the pseudo prepolymer is mixed with a first trimellitic acid alkyl ester.
The plasticizer and the second plasticizer composed of at least one of citrate, acetylated monoglyceride and polyetherester may be contained in an amount of 10 to 20 parts by mass with respect to 100 parts by mass of the mixture.

This configuration can be applied to a belt molding material used in the one-shot molding method. In that case, the mixture of polyisocyanate and polyol,
A first plasticizer comprising an alkyl trimellitate, and a second plasticizer comprising at least one of a citrate, an acetylated monoglyceride and a polyetherester.
10 parts by weight of plasticizer were added to 100 parts by weight of the mixture.
It may be contained up to 20 parts by mass.

[0023]

As described above, according to the present invention,
Both the first and second plasticizers are not specified as designated chemical substances by the PRTR method, and a transmission belt with a low environmental load can be obtained.

Further, since the prepolymer contains the first and second plasticizers so as to ensure appropriate surface lubricity and rigidity of the belt, a urethane-based plastic using DOP or DOA as a plasticizer is used. A transmission belt having performance equal to or higher than that of the transmission belt can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

(Configuration of Toothed Belt B) FIG. 1 shows a toothed belt B according to an embodiment of the present invention.

The toothed belt B is formed by a belt body 1 provided with belt teeth 2, 2,... At a predetermined pitch in the belt length direction on the inner peripheral surface. A core wire 3 as a tensile member extends along the bottom of each belt tooth 2 substantially in the belt length direction and is formed spirally with a pitch formed in the belt width direction. Further, a reinforcing cloth 4 is embedded so as to be located between the belt teeth 2, 2,.

The belt body 1 comprises a liquid prepolymer produced by synthesizing both the polyisocyanate component with TDI and the polyol component with PTMG, and adding 1,1'-methylenebis (o-chloroaniline) as a curing agent.
(Hereinafter referred to as “MOCA”), oleic acid as an organic acid as a reaction accelerator, mixed alkyl ester of trimellitic acid as an alkyl ester of trimellitic acid as a first plasticizer, and citrate ester as a second plasticizer And a material for forming a belt containing acetyltributyl citrate, which has undergone a curing reaction. Here, the ratio of the number of moles of amino groups contained in MOCA (curing agent) to the number of moles of isocyanate groups contained in the prepolymer is set to be 0.7 to 1.3. In addition, oleic acid (reaction accelerator) contains prepolymer 100
0.4 parts by mass with respect to parts by mass. further,
Trimellitic acid mixed alkyl ester (first plasticizer) and acetyltributyl citrate (second plasticizer) are contained in an amount of 10 to 20 parts by mass based on 100 parts by mass of the prepolymer. The trimellitic acid mixed alkyl ester (first plasticizer) is a plasticizer having low compatibility with the prepolymer, while acetyltributyl citrate (second plasticizer) is a plasticizer having high compatibility with the prepolymer. .

The core wire 3 is formed of a twisted aramid fiber, and is subjected to an adhesive treatment by dipping in an epoxy resin solution and heating.

The reinforcing cloth 4 is formed of a nonwoven fabric of cellulose fibers.

(Method of Manufacturing Toothed Belt B) Next, a method of manufacturing the toothed belt B will be described.

<Reinforcing cloth / core wire setting step> The peripheral surface of the inner mold in which the belt tooth forming grooves extending in the axial direction are provided at a predetermined pitch in the circumferential direction is coated with a nonwoven fabric of cellulose fiber as a reinforcing cloth. A core wire made of a twisted aramid fiber is spirally wound at a predetermined pitch. Then, the inner mold is set at the center of the cylindrical outer mold. At this time, a gap for injecting the urethane composition is formed between the inner mold and the outer mold.

<Belt forming material preparation step> TDI and P
The temperature of the prepolymer synthesized with TMG is controlled at 80 ° C. and the pressure is reduced to remove bubbles. Next, MOCA (curing agent), oleic acid (reaction accelerator), trimellitic acid mixed alkyl ester (first plasticizer), and acetyltributyl citrate (second plasticizer) in a container controlled at 100 ° C.
Are mixed to form a uniform solution, which is poured into a prepolymer and stirred to form a liquid belt forming material. At this time, the content of MOCA (curing agent) was adjusted so that the ratio of the number of moles of amino groups contained in MOCA (curing agent) to the number of moles of isocyanate groups contained in the prepolymer was 0.7 to 1.3. Set. Further, the content of oleic acid (reaction accelerator) is set to 0.4 parts by mass with respect to 100 parts by mass of the prepolymer. Furthermore, the content of each of the trimellitic acid mixed alkyl ester (first plasticizer) and acetyltributyl citrate (second plasticizer) is set to 10 to 20 parts by mass with respect to 100 parts by mass of the prepolymer.

<Belt forming material injecting / curing step> The obtained belt forming material is injected into a gap between the outer die and the inner die, and this is kept in an atmosphere of 100 ° C. for 15 minutes. Thereby, the curing reaction of the belt molding material proceeds.

<Demolding Step> The cylindrical belt precursor formed by curing the belt molding material from the outer die and the inner die is demolded.

<Width Cutting Step> The removed belt precursor is cut into a predetermined width to obtain a toothed belt B.

(Function / Effect) According to the belt molding material having the above structure, both the first and second plasticizers are DOP or DOA.
As described above, the specified chemical substance is not specified by the PRTR method, and the toothed belt B to be formed has a low load on the environment.

The first plasticizer has a low compatibility with the urethane prepolymer and, after curing, precipitates on the belt surface to impart surface lubricity, thereby realizing smooth contact with the pulley. It has the function of improving the life of the belt, but the first plasticizer is contained in the prepolymer to such an extent that its precipitation on the belt surface does not become excessive, while the second plasticizer has high compatibility with the prepolymer. Although it hardly changes the surface properties of the belt after being mixed into the belt body after curing, it affects the rigidity of the belt, but the second plasticizer is contained in the prepolymer to adjust the rigidity of the belt. The toothed belt B produced thereby has appropriate surface lubricity and rigidity, and DOP and DOP
It has a performance equal to or higher than that of a toothed belt using OA as a plasticizer.

(Other Embodiments) In the above embodiment,
Although the transmission belt formed of the belt forming material is a toothed belt, it is not particularly limited thereto, and may be a flat belt, a V belt, a V-ribbed belt, a round belt, or the like.

In the above embodiment, TDI was used as the polyisocyanate for forming the prepolymer.
The present invention is not particularly limited thereto, and may be diphenylmethane diisocyanate (MDI).

In the above embodiment, PTMG was used as the polyol for forming the prepolymer. However, the present invention is not particularly limited to this, and other polyether glycols such as polypropylene ether glycol (PPG) and polyethylene adipate may be used. Polyester glycols such as (PEA) and poly-ε-caprolactone glycol (PCL) may be used. However, when the crystallinity of the glycol is high, the effect of adjusting the hardness due to the inclusion of the plasticizer is small, so that polyether glycol is preferably used.

In the above embodiment, M is used as the curing agent.
Although OCA was used, the present invention is not particularly limited to this, and other diamines and polyols may be used.

In the above embodiment, oleic acid, which is an organic acid, is used as a reaction accelerator. However, the present invention is not limited to this, and aliphatic carboxylic acids such as sebacic acid and adipic acid, benzoic acid, and the like can be used. An aromatic carboxylic acid such as toluic acid may be used. However, oleic acid which is liquid at room temperature is particularly preferably used in consideration of workability such as compounding.

In the above embodiment, acetyl tributyl citrate was used as the second plasticizer. However, the present invention is not limited to this, and triethyl citrate (T
Other citrates such as EC), acetylated monoglycerides such as glycerol diacetyl monolaurate, and polyetheresters may be used.

In the above embodiment, only the first and second plasticizers are contained. In addition, fatty acid esters such as butyl stearate and triglycerides such as tallow and lard may be added. .

In the above embodiment, the belt molding material is composed of the prepolymer, the curing agent, the organic acid, and the first and second plasticizers. However, the present invention is not limited to this. May contain a pigment or a lubricant.

In the above embodiment, a twisted yarn of aramid fiber is used as the core wire 4. However, the present invention is not particularly limited to this, and a twisted yarn of polyester fiber or the like may be used.

In the above embodiment, when the toothed belt B is manufactured, the temperature of the prepolymer is adjusted to 80 ° C., the temperature of the curing agent is adjusted to 100 ° C., and the heating time is set to 15 ° C. However, the temperature of the prepolymer is 60 to 100 ° C., the temperature of the curing agent is 100 to 150 ° C., and the temperature of the prepolymer is 100 to 150 ° C., depending on the type of the prepolymer or the curing agent. Mold temperature is 100-150
C and the heating time should be appropriately selected in the range of 10 to 90 minutes.

In the above embodiment, the toothed belt B is manufactured by the prepolymer method, but may be manufactured by the one-shot method or the pseudo-prepolymer method. In the former case, a first plasticizer comprising trimellitic acid mixed alkyl ester and a second plasticizer comprising acetyl tributyl citrate are added to a mixture of a pseudo prepolymer produced by synthesizing TDI and PTMG and PTMG or another polyol. 10 to 10 parts by weight of the mixture
What is necessary is just to contain 20 mass parts. In the latter case, TDI and P
The mixture with TMG may contain 10 to 20 parts by mass of a first plasticizer composed of an alkyl ester of trimellitic acid and a second plasticizer composed of acetyl tributyl citrate with respect to 100 parts by mass of the mixture.

[0050]

Example (Test Evaluation Sample Belt) Example 1 A prepolymer consisting of TDI and PTMG was added to MOCA (a product name of Ihara Chemical Co., Ltd.) as a curing agent.
Cureamine MT) and a belt molding material containing ATBC (manufactured by Sanken Kako Co., Ltd.) as a plasticizer are cured by a curing reaction to form a toothed belt having a belt body according to the above-described embodiment. And made it as Example 1. At this time, the content of MOCA (curing agent) was adjusted
13 parts by mass with respect to 0 parts by mass. ATBC
The content of the (plasticizer) was 30 parts by mass with respect to 100 parts by mass of the prepolymer. The toothed belt has a circumference of 900 mm,
A belt having a belt width of 20 mm and a belt tooth pitch of 8 mm was prepared.

Example 2 A prepolymer comprising TDI and PTMG was added to MOCA (a product of Ihara Chemical Co., Ltd.) as a curing agent.
Cureamine MT), trimellitic acid mixed alkyl ester (C-79, manufactured by Asahi Denka Kogyo Co., Ltd.) as a first plasticizer, and ATBC (manufactured by Sanken Kako Co., Ltd.) as a second plasticizer. The toothed belt having the belt body formed by the curing reaction of the formed belt molding material was prepared by a method according to the above-described embodiment. At this time, the content of MOCA (curing agent) was changed to 100
It was 13 parts by mass with respect to parts by mass. The content of the trimellitic acid mixed alkyl ester (first plasticizer) was set to 5 parts by mass with respect to 100 parts by mass of the prepolymer.
The content of the (second plasticizer) was 25 parts by mass with respect to 100 parts by mass of the prepolymer. The toothed belt has a circumference of 900 mm, a belt width of 20 mm, and a belt tooth pitch of 8 as in Example 1.
mm.

Example 3 The content of trimellitic acid mixed alkyl ester (first plasticizer) was set to 10 parts by mass relative to 100 parts by mass of prepolymer, and the content of ATBC (second plasticizer) was changed to prepolymer 1
Example 3 was a toothed belt having the same configuration as Example 2 except that the amount was 20 parts by mass with respect to 00 parts by mass.

Example 4 The content of the trimellitic acid mixed alkyl ester (first plasticizer) was set to 15 parts by mass with respect to 100 parts by mass of the prepolymer, and the content of ATBC (second plasticizer) was changed to prepolymer 1
Example 4 was a toothed belt having the same configuration as Example 2 except that the amount was 15 parts by mass with respect to 00 parts by mass.

Example 5 The content of the trimellitic acid mixed alkyl ester (first plasticizer) was set to 20 parts by mass with respect to 100 parts by mass of the prepolymer, and the content of ATBC (second plasticizer) was changed to prepolymer 1
Example 5 was a toothed belt having the same configuration as that of Example 2 except that 10 parts by mass was used with respect to 00 parts by mass.

Example 6 The content of the trimellitic acid mixed alkyl ester (first plasticizer) was set to 5 parts by mass based on 100 parts by mass of the prepolymer, and the content of ATBC (second plasticizer) was changed to prepolymer 1
Example 6 was a toothed belt having the same configuration as that of Example 2 except that the amount was 25 parts by mass with respect to 00 parts by mass.

Example 7 A prepolymer consisting of TDI and PTMG was added to MOCA (a product name of Ihara Chemical Co., Ltd.) as a curing agent.
Cureamine MT) and a mixed alkyl ester of trimellitic acid as a plasticizer (trade name C- manufactured by Asahi Denka Kogyo KK)
79), a toothed belt having a belt body formed by a curing reaction of the belt-forming material containing the same was prepared by a method according to the above-described embodiment, and this was designated as Example 7. At this time, M
The content of OCA (curing agent) was 13 parts by mass with respect to 100 parts by mass of the prepolymer. The content of the trimellitic acid mixed alkyl ester (plasticizer) was 30 parts by mass with respect to 100 parts by mass of the prepolymer. As in Example 1, the toothed belt had a circumference of 900 mm, a belt width of 20 mm, and a belt tooth pitch of 8 mm.

Example 8 A prepolymer composed of TDI and PTMG was added to MOCA (a product of Ihara Chemical Co., Ltd.) as a curing agent.
Cureamine MT) and DOA as a plasticizer (manufactured by Sanken Kako Co., Ltd.), and a toothed belt having a belt body made of a belt molding material is prepared by a method according to the above-described embodiment. Was set to Example 8. At this time, MOCA
The content of (curing agent) was 13 parts by mass with respect to 100 parts by mass of the prepolymer. The content of DOA (plasticizer) was set to 30 parts by mass with respect to 100 parts by mass of the prepolymer. The toothed belt has a circumference of 900 mm and a belt width of 20 m, as in Example 1.
m and a belt tooth pitch of 8 mm.

(Test Evaluation Method) <Precipitation State of Plasticizer Belt Surface> The surface of each toothed belt according to Examples 1 to 7 manufactured was observed, and the belt surface of the plasticizer was determined based on Example 8 which is a conventional example. The state of precipitation on the surface was evaluated on a five-point scale of "many", "somewhat many", "equivalent", "somewhat small", and "small".

<Durability Test> The toothed belts according to Examples 1 to 8 were wound around a driving pulley having a diameter of 75 mm and 30 pulley teeth and a driven pulley having a diameter of 75 mm and 30 pulley teeth and driven. The number of rotations of the pulley is 1800 rpm, the load of the driven pulley is 0.49 N · m, and the initial tension of the belt is 3
The belt was run under the conditions of 9.2 N. Then, the running time of the belt from the start of running of the belt to the cutting was measured. The evaluation of the belt life was performed by representing the belt running time of Example 8 as 100 and those of Examples 1 to 7 as relative indexes.

(Test Results) Table 2 shows the test results.

[0061]

[Table 2]

According to the table, the content of the trimellitic acid mixed alkyl ester (first plasticizer) was high and the ATBC
It is understood that when the content of the (second plasticizer) is reduced, the amount of the plasticizer deposited on the belt surface increases, and the life of the belt increases. This is because the trimellitic acid mixed alkyl ester (first plasticizer) has low compatibility with the prepolymer and precipitates on the belt surface after curing, thereby imparting lubricity to the belt surface and smooth contact with the pulley. This is considered to be because the durability of the belt is enhanced.

Further, the content of the trimellitic acid mixed alkyl ester (first plasticizer) is low and the ATBC (second plasticizer)
It can be seen that when the content of the (plasticizer) is increased, the amount of the plasticizer deposited on the belt surface decreases, and the belt life is shortened. This is considered to be because ATBC (second plasticizer) has a high compatibility with the prepolymer and is mixed into the belt main body after curing, so that smooth contact between the belt and the pulley cannot be realized.

The total content of the first and second plasticizers was 30 parts by mass with respect to 100 parts by mass of the prepolymer, and although not shown in Table 2, the hardness Hs of each belt was about 80. ° (JIS A), it can be seen that ATBC (second plasticizer) has an effect on the rigidity of the belt.

In Examples 3 to 5, the belt body containing a prepolymer containing an appropriate amount of trimellitic acid mixed alkyl ester (first plasticizer) and an appropriate amount of ATBC (second plasticizer) was subjected to a curing reaction, whereby the belt body was cured. Thus, surface lubricity is imparted by moderate precipitation of a plasticizer on the belt surface and moderate rigidity is adjusted, and is equal to or more than that of Example 8 using DOA as a plasticizer (with a belt life of ± 1).
(The range of 0% is considered to be the same level).

[Brief description of the drawings]

FIG. 1 is a side view of a toothed belt B according to an embodiment of the present invention.

[Explanation of symbols]

 B Toothed belt 1 Belt body 2 Belt teeth 3 Core wire 4 Reinforcement cloth

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F16G 1/16 F16G 1/16

Claims (4)

[Claims] 1. A belt molding material used for producing a power transmission belt made of urethane by injecting into a mold for belt molding and performing a curing reaction, and is produced by synthesizing a polyisocyanate and a polyol. A first plasticizer comprising an alkyl trimellitate, and a second plasticizer comprising at least one of citrate, acetylated monoglyceride and polyetherester, based on 100 parts by mass of the prepolymer. A material for forming a belt, comprising 10 to 20 parts by mass. 2. A belt-forming material used for producing a power transmission belt made of urethane by injecting into a belt-forming mold and performing a curing reaction, which is produced by synthesizing a polyisocyanate and a polyol. A mixture of the pseudo-prepolymer and the same or different polyol as the polyol constituting the pseudo-prepolymer, a first plasticizer comprising an alkyl trimellitate, and a citrate, an acetylated monoglyceride, and a polyether ester. At least one second plasticizer is used in an amount of 10 to 10 parts by mass of the mixture.
A material for forming a belt, comprising 20 parts by mass. 3. A belt molding material used for producing a power transmission belt made of urethane by injecting it into a belt molding die and performing a curing reaction, wherein trimellitic acid is added to a mixture of a polyisocyanate and a polyol. The first plasticizer composed of an alkyl ester and the second plasticizer composed of at least one of citric acid ester, acetylated monoglyceride, and polyether ester are each added in an amount of 10 to 20 parts by mass based on 100 parts by mass of the mixture.
A material for forming a belt, which is contained by mass. 4. A transmission belt, wherein the belt molding material according to claim 1 is cured to form a belt main body.