JP2543186B2 - Timing belt - Google Patents

Description

TECHNICAL FIELD The present invention relates to improvements in timing belts.

[Conventional technology]

BACKGROUND ART Conventionally, a polyurethane elastic body has been widely used as a timing belt because it has a more beautiful appearance and does not fall off rubber (hereinafter referred to as Prior Art I). However, since polyurethane has a high coefficient of friction, when it is used for a timing belt, meshing with the toothed pulley becomes unstable and tooth jumping is likely to occur. As a result, the timing belt made of the conventional technique I has problems that noise is generated and the transmission efficiency is reduced.
Further, the abrasion resistance was poor, and the belt durability was also problematic.

Therefore, polyurethane, aliphatic amide, which is a lubricant,
A timing belt having a friction coefficient reduced by adding an aromatic amide, Teflon or paraffin has been proposed (hereinafter referred to as Prior Art II).

Furthermore, Japanese Utility Model Publication No. 57-194946 discloses that polyurethane resin is made of graphite, tetrafluoroethylene, resin powder,
A device relating to a wear-resistant transmission belt characterized by containing a lubricant such as paraffin, molybdenum disulfide, and wax is disclosed (hereinafter referred to as prior art III).

In the timing belt according to the conventional technique II, the conventional technique I
The problems such as tooth jumping, noise generation, and reduction of transmission efficiency due to instability of meshing, which were seen in Section 3, were eliminated.
By the way, when a lubricant such as an aliphatic amide or an aromatic amide is added to polyurethane, the coefficient of friction is lowered, while the physical properties of urethane such as shear strength and abrasion resistance are lowered. That is, the timing belt according to the related art II has a low friction coefficient, but also has low shear strength of the belt tooth portion and poor wear resistance, and thus has no durability. Furthermore, polyurethanes containing lubricants such as the above aliphatic amides and aromatic amides have poor adhesion to nylon and polyester fibers, so polyurethane polyurethane timing belts with nylon or polyester sailcloth or non-woven fabric reinforced at the teeth are recommended. When the above lubricant was added, the durability of the belt was markedly reduced.

Further, in the power transmission belt according to the conventional technique III, lubricants such as graphite, tetrafluoroethylene, resin powder, molybdenum disulfide, etc. increase the viscosity of polyurethane and deteriorate the processability. Lubricants such as paraffin and wax are likely to separate into two layers during kneading.
Furthermore, the addition of these lubricants tends to deteriorate the balance of physical properties (balance between strength and elongation).

[Problems to be Solved by the Invention]

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a timing belt having a low friction coefficient, good physical properties, and extremely excellent durability. It is in.

[Means for solving the problem]

In order to achieve the above object, the gist of the present invention is to add 100 parts by weight of a polyurethane elastic material to a fatty alcohol ester 3 to
The timing belt is characterized by using a composition to which 0 part by weight is added.

[Action]

According to the present invention, the frictional coefficient can be reduced by adding the fatty alcohol ester to the polyurethane elastic body, and further, the shear strength and abrasion resistance of the belt tooth portion can be improved and the belt durability can be improved. And, even if the fatty alcohol ester is added to the polyurethane elastic body, the adhesiveness with nylon or polyester fiber is not deteriorated, so by adding the fatty alcohol ester, the tooth portion is reinforced with nylon or polyester canvas or non-woven fabric. The durability of the polyurethane timing belt is dramatically improved.

[Example] A C8M type timing belt comprising 100 parts by weight of a polyurethane elastic body and 3 to 20 parts by weight of stearyl stearate (Rikemar SL900 manufactured by Riken Vitamin) as a fatty alcohol ester (Example) )
And a C8M type timing belt consisting only of polyurethane elastic material (Comparative Example 1), and 100 parts by weight of polyurethane elastic material with higher fatty acid amide (trade name Alflo manufactured by NOF CORPORATION).
A C8M type timing belt (Comparative Example II) was prepared by adding 5 parts by weight of P10). Then, in order to compare the friction coefficient, tensile strength, abrasion resistance, belt tooth portion shear strength, adhesiveness, belt endurance time, etc. of these timing belts, tests were conducted according to the following methods.

Friction coefficient HEIDN 14 type tester, vertical load 200g, moving speed 2
It was set to 5 mm / min. (Temperature = 20 ° C) Tensile Strength According to JIS K6301, a tensile test was conducted using a dumbbell No. 2 test piece size.

Abrasion resistance A Taber abrasion test was conducted, and the roughness of the worn wheel was H22, the number of revolutions was 1000, and the load was 1 kg.

Belt tooth shear strength As shown in the figure, a jig 2 having a protrusion 1 and a support plate 3
The S8M type timing belt 4 with a width of 15 mm is sandwiched between the two, and the timing belt 4 is moved downward at a speed of 50 mm / min while restraining the horizontal movement of the timing belt, and the jig 2
Was measured by the method of measuring the strength when the tooth portion 5 of the timing belt 4 is sheared by the protruding portion 1.

Adhesiveness Nylon film is adhered and the peeling speed is set to 50 mm / min, 180 ° peeling test is performed, and the force (kg / c
m) was measured.

Belt endurance time A timing belt is hung on two pulleys with 28 teeth and the tension of the belt is 40 kg and the load is 1.7 kg.m.
The pulley was rotated at 750 R / M, and the time until a crack was generated in the belt was measured.

As a result of the above test, the results shown in the following table were obtained.
In the table, the tooth portion reinforcing belt means a belt having tooth portions reinforced with nylon.

In the comparison between the examples and comparative examples in the table on the previous page, the following points are clear.

1) Comparative Example 1 in which nothing was added was inferior to the Examples in all other physical property values except that the adhesiveness was at the same level as the Example in which stearyl stearate was added.

2) Comparative Example 2 in which the fatty acid amide was added was inferior to the Examples in which stearyl stearate was added in all other physical property values except that the friction coefficient was low.

3) The example in which stearyl stearate was added had a lower friction coefficient, improved tensile strength, belt tooth shear strength, and wear resistance, and adhesiveness was a comparative example compared to the comparative example. It is the same level as 1. As a result, the belt durability was improved. In particular, the durability of the tooth reinforcing belt is significantly improved.

When the amount of stearyl stearate added was as small as 3 parts by weight, the coefficient of friction was not so low, and there was little margin for improving the strength and wear resistance relative to the comparative example.
The durability of the belt is not so much improved as compared with the comparative example.

Further, when the amount of stearyl stearate added is as large as 20 parts by weight, the friction coefficient is also considerably reduced, while the strength and wear resistance are at the same level as those of the added amount of 15 parts by weight or slightly reduced, and the belt The durability of is lower than that of 15 parts by weight.

Therefore, in order to obtain a timing belt having a low friction coefficient, good strength and wear resistance, and extremely excellent belt durability, the amount of stearyl stearate added to the polyurethane elastic body is 5 to 15 parts by weight. Is particularly preferable.

Similar effects can be expected by using cetyl stearate, palmityl stearate, myristyl stearate, or the like as the fatty alcohol ester instead of stearyl stearate.

When the fatty alcohol ester is added to the polyurethane elastic body, it is not always necessary to add and mix it in the entire surface, and it may be partially added depending on the function of the power transmission belt.

〔The invention's effect〕

A timing belt according to the present invention, which is characterized by using a composition obtained by adding 3 to 20 parts by weight of a fatty alcohol ester to 100 parts by weight of a polyurethane elastic body, has the following effects.

Since the coefficient of friction can be lowered, tooth jumping and noise due to unstable meshing do not occur, and transmission efficiency does not decrease.

The tensile strength, the shear strength of the teeth and the wear resistance are improved, and the durability of the timing belt is improved.

Since the adhesiveness with nylon or polyester fibers does not deteriorate, the durability is remarkably improved in the timing belt in which the tooth portion is reinforced with these canvas and non-woven fabric.

[Brief description of drawings]

The figure is a figure explaining the test method of a belt tooth part shear strength. 1 ... Projection part, 2 ... Jig, 3 ... Support plate, 4 ... Timing belt, 5 ... Tooth part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI technical display location // B29K 75:00 (56) References JP-A-59-68348 (JP, A) JP-A-SHO 60-213602 (JP, A) JP-A-60-213603 (JP, A) JP-A-63-112658 (JP, A) JP-A-54-124100 (JP, A) JP-A-62-147141 (JP, A) A) JP 63-23045 (JP, A) JP 60-212438 (JP, A) Actually opened 63-129750 (JP, U) Actually opened 63-62651 (JP, U) Actually opened 57 -194946 (JP, U)

Claims (1)

(57) [Claims] 1. A timing belt comprising a composition obtained by adding 3 to 20 parts by weight of a fatty alcohol ester to 100 parts by weight of a polyurethane elastic body.