JPS5830139B2 - power transmission belt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides extended segments comprising long chain ester repeat units derived from dicarboxylic acids and long chain glycols and short chain ester repeat units derived from dicarboxylic acids and low molecular weight diols. The present invention relates to a power transmission belt formed from a thermoplastic copolyetherester elastomer.

There are a variety of applications for nidistomer materials that require high modulus and high ultimate strength.

Such applications are, for example, flat power transmission belts and V-power transmission belts.

Of course, for such applications, some flexibility must exist within the belt.

In the past, satisfactory power transmission belts have been made from various types of elastomers reinforced with fibers such as nylon.

Unreinforced nidistomers do not have sufficient modulus and strength to be used in power transmission belts except in light power applications.

Attempts to use such reinforced nidistomers have resulted in the problem that multiple steps are required to produce the nidistomers.

The reinforcing cord would have to be surrounded by a nystomer, which cannot be conveniently done.

Therefore, there is a need to produce materials in an economical one-step operation that can be satisfactorily used as high power transmission belts.

In accordance with the present invention, it has been unexpectedly discovered that certain copolyetherester elastomers can be processed to produce products having the desired properties described above.

The copolyetherester will stretch and substantially maintain its length at a temperature at least 20'F (11'C) below the melting point of -t at an elongation weight of at least 300% but below its break point. While its melting point is about 15
The heat setting temperature must be brought to or maintained at 0 to 20 degrees below (83 to 11°C) and then cooled to at least 100 degrees below (56 degrees C) below the heat setting temperature.

The resulting product has outstanding tensile modulus and strength for uses such as power transmission belts.

Additionally, it has a small amount of elasticity, so it can be stretched somewhat if desired.

A small amount of elasticity means that it has an ultimate elongation of at least 40-60%.

The copolyether ester elastomers to be treated according to the invention consist essentially of internal linear long chain ester repeat units and short chain ester repeat units linked head-to-tail by ester linkages, the long chain ester units having the formula is the divalent group remaining after removing the terminal hydroxyl group from a poly(alkylene oxide) glycol having a carbon to oxygen ratio of about 2.0 to 4.3, and R has a molecular weight of about 300 or less. It is a divalent group that remains after removing a carboxyl group from a dicarboxylic acid, and DI/'
i The divalent group remaining after removing the hydroxyl group from a diol having a molecular weight of about 250 or less, provided that the short chain ester units constitute about 15 to 95 weight units, preferably 25 to 90 weight units, of the copolyether ester. and therefore the long chain ester units are about 5 to 85 of the copolyether ester.
The weight is preferably 10 to 75 weight.

The term "long chain ester unit" used as a unit in a polymer chain refers to the reaction product of a long chain glycol and a dicarboxylic acid.

Such a "long chain ester unit" is a repeating unit in the copolyether ester of the present invention, and is a repeating unit of the above formula (I
).

Long chain glycols have terminal (or as close as possible to the terminal) hydroxyl groups and have a molecular weight of about 400 to 600.
It is a polymeric glycol that is 0.

The long chain glycols used to make the epoxyether esters of this invention have a carbon to oxygen ratio of about 2.0.
~4.3 and is poly(alkylene oxide) glycol.

A typical long-chain glycol is poly(ethylene oxide)
Glycol, poly(1,2-$- and l.

3-propylene oxide) glycol, poly(tetramethylene oxide) glycol, random or block copolymers of ethylene oxide and 1,2-propylene oxide, and tetrahydrofuran and small amounts of second monomers such as 3-methyltetrahydrofuran. Random or block copolymers are used in proportions such that the molar ratio of carbon to oxygen in the glycol does not exceed about 4.3.

"Short chain ester unit" as used as a unit in a polymer chain means a low molecular weight compound or polymer chain unit having a molecular weight of about 550 or less.

It is produced by reacting a low molecular weight diol (molecular weight less than about 250) with a dicarboxylic acid to produce an ester unit represented by formula (II) above.

Low molecular weight diols that react to form short chain ester units include fatty acids, cycloaliphatic and aromatic dihydroxy compounds.

Preferred diols have 2 to 15 carbon atoms, such as ethylene glycol, propylene gelyl, tetramethylene glycol, pentamethylene glycol, 2
．． These include 2-dinotilto9methylene glycol, hexamethylene glycol, decamethylene glycol, dihydroxycyclohexane, cyclohexane dimetatool, resorcinol, hydroquinone, and 15-dihydroxynaphthalene.

Particularly preferred are aliphatic diols having 2 to 8 carbon atoms.

Among the bisphenols that can be used are bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)methane, and bis(p-hydroxyphenyl)propane.

Equivalent ester-forming derivatives of diols are also useful (eg, ethylene oxide or ethylene carbonate can be used in place of ethylene glycol).

As used herein, "low molecular weight diol" should be understood to include such equivalent ester-forming derivatives.

75) The requirement regarding molecular weight is only for diols and not for their derivatives.

The dicarboxylic acids that react with the aforementioned long chain glycols and low molecular weight diols to form the copolyesters of the present invention are aliphatic, cycloaliphatic or aromatic dicarboxylic acids of low molecular weight, i.e., molecular weight of about 300 or less. .

As used herein, "dicarboxylic acid" includes equivalents of dicarboxylic acids having two functional carboxyl groups that behave substantially like dicarboxylic acids in reaction with glycols and diols to form copolyester polymers. .

These equivalents include esters and ester-forming derivatives such as acid halides and anhydrides.

Molecular weight requirements apply to acids and not to esters or ester-forming derivatives of their equivalents.

Therefore, any ester of a dicarboxylic acid having a molecular weight greater than 300 or the acid of a dicarboxylic acid having a molecular weight greater than 300 is included as long as the molecular weight of the acid is about 300 or less.

The dicarboxylic acid can contain substituents and combinations thereof that do not substantially interfere with the formation of the copolyester polymer and the use of this polymer in the present invention.

Aliphatic dicarboxylic acid, as used herein, means a carboxylic acid having two carboxyl groups, each attached to a saturated carbon atom.

The acid is Idm aliphatic when the carbon atom to which the carboxyl group is attached is saturated and is present in the ring.

Aliphatic or cycloaliphatic acids with conjugated unsaturation are often unusable because they homopolymerize.

However, some unsaturated acids can be used, such as maleic acid.

As used herein, the aromatic dicarboxylic acid is defined as a
It is a dicarboxylic acid with two carboxyl groups.

It is not necessary that both functional carboxyl groups are attached to the same aromatic ring, and when two or more rings are present, these rings may be aliphatic or aromatic divalent groups or -O- Alternatively, it can be bonded by a divalent group such as 18O2-.

Representative aliphatic and cycloaliphatic acids that can be used in the present invention include sebacic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, and glutaric acid. , carbonic acid, oxalic acid, azelaic acid, diethylmalonic acid, allylmalonic acid, 4-cyclohexene-1,2-i;'t) rubonic acid, 2-ethylsperic acid, 2.2,3.3-tetramethylsuccinic acid , cyclopencune dicarboxylic acid, decahydro-1,5-
Naphthalenedicarboxylic acid, 4,4'-bicyclohexyldicarboxylic acid, decahydro-2,6-naphthalenedicarboxylic acid, 4,4'-methylenebis(cyclohexanecarboxylic acid, L3,4-furandicarboxylic acid, and 1,1-
Cyclobutanedicarboxylic acid.

The preferred aliphatic acids are cyclohexane-dicarboxylic acid and adipic acid.

Typical aromatic dicarboxylic acids that can be used include terephthalic acid, phthalic acid, isophthalic acid, bibenzoic acid, dicarboxylic compounds substituted with two benzene nuclei, such as bis(p-carboxyphenyl)methane, p-oxy (p-
carboxyphenyl)benzoic acid, ethylene-bis(p-
oxybenzoic acid), 1,5-naphthalene dicarboxylic acid,
2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, phenanthenedicarboxylic acid, anthracene dicarboxylic acid, 4,4'-sulfonylbibenzoic acid,
and C1-C12 alkyl and ring-substituted derivatives thereof, such as halo, alkoxy and aryl derivatives.

Hydroxylic acids such as p(β-hydroxyethoxy)benzoic acid can be used if aromatic dicarboxylic acids are also present.

Aromatic dicarboxylic acids are a particularly preferred group for preparing the copolyetherester polymers of the present invention.

Among the aromatic acids, those having 8 to 16 carbon atoms are preferred, especially phenylenedicarboxylic acids, namely phthalic acid, terephthalic acid and isophthalic acid, and their dimethyl derivatives.

at least about 50 short chain segments are identical, and these identical segments form a homopolymer having a fiber-forming molecular weight range (molecular weight >5000) and a melting point as high as at least 150°C, preferably as high as 200°C. It is preferable to do so.

Polymers that meet these requirements exhibit useful levels of properties such as tensile strength and tear strength.

The melting point of the polymer can be conveniently determined by differential scanning calorimetry.

The short chain ester units are about 15 in the copolyether ester.
~95 constitutes a weight salary.

The remainder of the copolyetherester is long chain segments, so the long chain segments make up about 5 to 85 folds of the copolyetherester.

Short chain units make up 25 to 90 weight units and long chain units make up 10 to 90 weight units.
Copolyether elastomers comprising more than 75% by weight are preferred.

The preferred copolyetherester is prepared from dimethyl ester of terephthalic acid, poly(tetramethylene oxide) glycol having a molecular weight of about 600-2000, and 1,4-butanediol.

To produce power transmission belts, the copolyetherester is heated to a temperature of at least 20 degrees below its melting point (11°C) and reduced to at least 30% of its original length by conventional methods.
00%, preferably at least 400%.

It can be stretched at any point below its breaking point.

As will be appreciated, the exact length required for a given application will vary, but it has been found that the copolyetherester must be stretched to at least 300% of its original length to obtain the desired properties. emphasized.

Stretching ratio as low as 300% or 20 below the melting point (
Stretching at a temperature lower than 11° C.)
The copolyether ester is not sufficiently stretched (orientated) to provide a sufficiently high tensile modulus and strength for use at high power.

Copolyetherester Yosu 20 below (11
℃) Any temperature as low as 1 can be used.

Preferably, a coating temperature of about 60° C. (33° C.) below the melting point, and more preferably 160° C. below the melting point, can be utilized.

Then, the copolyetherester elastomer with
Substantially this length must be maintained for heat setting.

Again, any known method can be used to hold the copolyetherester elastomer at this length, such as clamps.

The stretched copolyether elastomer must have a heat setting temperature of about 150 to 20 degrees below its melting point (83 to 11 °C); when the copolyether ester is stretched below this range, no heat is applied. Raise the lever to the heat setting temperature.

On the other hand, when stretched at a temperature within this heat-setting range, the stretching and heat-setting temperatures are the same and a separate step of adding b1 heat is unnecessary.

Generally, heat setting operations require only a momentary residence time over the heat setting temperature range VC, but the length of time at this heat setting temperature is not critical.

A long time can be used, but from an economic point of view this time should be kept as short as possible.

Typically, the melting point is below 340-420 (171-216
℃), preferably 230-410℃ (110-210℃)
).

For the preferred copolyetheresters described above, about 3
A heat setting temperature of 30-390"F (166-199C) is utilized.

As a result of the stretching (orientation) resulting from stretching and heat setting of the copolyetherester, it has very different properties compared to before these operations.

For example, the elongation at break for certain copolyetherester slabs is about 30-120%, preferably about 40-7
It is 0 excellent.

Before stretching and heat setting, the elongation at break is approximately 300-9
oO%, preferably about 500-800%.

The physical properties of oriented copolyetheresters are excellent.

Both the tensile modulus and tensile strength of unreinforced stretched polymers are similar to those of conventional nidistomers reinforced with fibers or fabric foils.

Ultimately, oriented copolyetheresters are suitable for applications requiring reinforcement, such as power transmission belts, but have the benefit of not requiring expensive fabrication steps to form reinforcements.

Another benefit of the stretched polymer over its unstretched state is that it can retain its length at elevated temperatures, thereby making it more suitable for use at higher temperatures.

Moreover, it is also a low hysteresis elastic material.

The combination of these properties is desirable in materials from which power transmission belts are made.

This is because this combination generates less heat, resulting in much lower operating temperatures when the belt is used at high power.

Therefore, a product has been produced that has both high strength and low flexibility.

This flexibility allows elongation at break of 40-60%.

Such products can be easily used as power transmission belts.

Cooling of the copolyetherester after heating can be accomplished by any desired means.

The preferred method is cooling at room temperature, but external cooling to ambient temperature can be achieved if necessary.

The pressure required to hold the copolyetherester at the desired elongation can be applied by conventional means such as appropriately sized clamps until the temperature is at least 100 degrees below (56°C) below the heat setting temperature. This pressure will not be released.

A transmission belt made of stretched copolyetherester can be manufactured by a conventional method.

For example, a billet is formed from the polymer by conventional methods, and the billet is stretched by stretching, heat setting, and cooling the billet according to the method of the present invention.

Then, both ends of the thus stretched copolyether ester having a desired length are joined to form an endless belt by adhesion using an adhesive or by fusion of both ends by heating near both ends.

Another method that can be used is to form a circular band from the copolyetherester by conventional methods and then stretch the band.

The latter method does not require forming a joint on the belt.

The copolyether esters described herein can be conveniently prepared by conventional transesterification reactions.

Preferred operations are the following 9. Dicarboxylic acids, such as dimethyl ester of terephthalic acid, and long chain glycols, such as poly-9 having a molecular weight of about 600 to 2000.
(tetramethylene oxide) glycol and a molar excess of a diol, such as 1,4-butanediol,
Heating is carried out in the presence of a catalyst to about 150 DEG -260 DEG C. at 0.5 to 5 atmospheres, preferably at ambient pressure, and at the same time the methanol produced by the transesterification is distilled off.

Depending on the temperature, catalyst, glycol excess, and equipment, the reaction is complete in a few minutes, such as 2 minutes, to several hours, such as 2 hours.

With respect to the molar ratio of the reactants, at least about 1.1 moles of diol per mole of acid, preferably less than about 1.2 moles of diol, per mole of acid.
There should be 5 moles of diol present.

Long chain glycol is about 0.0 per mole of dicarboxylic acid
025-0.85 mol, good! It should be present in an amount of 0,0 to 0.6 mol.

This operation produces a low molecular weight prepolymer, which is converted into the high molecular weight copolyetherester of the present invention by the operation described below.

Alternatively, such prepolymers can be prepared by several alternating esterification or transesterification methods, such as combining long-chain glycols with homopolymers or copolymers of short-chain esters of high or low molecular weight and the presence of a catalyst. The reaction can be carried out at l where randomization occurs.

Homopolymers or copolymers of short chain esters can be prepared from dimethyl esters and low molecular weight diols as described above, or by transesterification from the free acid button and diol acetate.

Alternatively, short chain ester copolymers can be prepared, for example, by direct esterification of suitable acids, anhydrides or acid chlorides with diols, or by reaction of acids with cyclic ethers or carbonates. It can be manufactured by other methods.

As is clear, prepolymers could also be made by carrying out these methods in the presence of long chain glycols.

The obtained prepolymer is then brought to a high molecular weight by distilling off excess short chain diols.

This method is known as "po9 condensation". This po9
Additional transesterification occurs during condensation, which increases the molecular weight and randomizes the arrangement of the copolyetherester units.

This final distillation or po-9 condensation is carried out at a temperature of about 200-270° C. at a pressure of less than about 5 hours for up to about 2 hours, e.g.
Excellent results are obtained with normal amounts when carried out for 5 to 1.5 hours.

The most practical polymerization method is one that relies on transesterification to complete the polymerization reaction.

Catalysts should be used in the transesterification reaction to avoid excessive holding times at high temperatures where irreversible thermal decomposition may occur.

Although a variety of catalysts can be used, it is preferred to use organic titanates, such as tetrabutyl titanate, alone or in combination with magnesium acetate or calcium acetate.

titanate complexes, such as MgCHTi(OR)6]
Complexes derived from alkoxides of alkali metals or alkaline earth metals and titanate esters, such as 2, are also very effective.

Inorganic titanates such as lanthanum titanate, calcium acetate/antimony trioxide mixtures, and lithium and magnesium alkoxides are other typical catalysts that can be used.

The catalyst should be present in an amount of 0.005 to 0.2 by weight based on total reactants.

Transesterification polymerization is generally carried out in the melt without added solvent, although inert solvents can be used to facilitate removal of volatile components from the mass at low temperatures.

This technique is particularly valuable in the production of prepolymers, for example by direct esterification.

However, certain low molecular weight diols, such as butadiol in terphenyl, are conveniently removed by azeotropic distillation during polymerization.

Both batch and continuous methods can be employed at any stage of the production of the copolyetherester.

Alternatively, the solid prepolymer separated in the solid phase can be heated in vacuum or in a stream of inert gas to remove liberated low molecular weight diols, thereby producing a prepolymer. - It is also possible to carry out polycondensation.

This process has the benefit of reducing decomposition since it must be carried out at temperatures below the softening point of the prepolymer.

The carboxylic acid or derivative thereof and the polymeric glycol are added to this final product in the same molar ratio as present in the transesterification mixture.

The amount of low molecular weight diol actually added corresponds to the difference between the number of moles of diacid and the number of moles of polymeric glycol present in the reaction mixture.

When a mixture of low molecular weight diols is used, the amount of each diol added is generally a function of the diols present, their boiling points, and relative reactivities.

The total amount of diol added is the difference between the number of moles of diacid and the number of moles of polymer.

The most preferred copolyesters stabilized by the method of the invention are dimethyl terephthalate, 71.4-butanediol, and poly(
tetramethylene oxide) glycol or poly(ethylene oxide) glycol having a molecular weight of about 600 to 1,500.

If desired, about 30 mole %, preferably 5 to 20 moles, of dimethyl terephthalate in these polymers can be replaced by dimethyl phthalate or dimethyl isophthalate.

Other preferred copolyesters are dimethyl terephthalate, 1,4-butanediol, and molecular weights from about 600 to 1
600 poly(propylene oxide) glycol.

30 moles, preferably 10 to 250 to 25 moles, by replacing ruphthalate with dimethyl isophthalate or replacing butanediol with neopentyl glycol up to about 30%, preferably 10 to 25%. Short chain ester units can be derived from neopentyl glycol in these poly(propylene oxide) glycol polymers.

Polymers based on poly(tetramethylene oxide) glycol are particularly preferred because they are easy to prepare, have good overall physical properties, and are particularly water resistant.

The most preferred copolyetherester compositions may further contain about 5% by weight of an antioxidant, such as about 0.2-5% by weight, preferably about 0.5-3% by weight. .

The most preferred antioxidants are diarylamines, such as 4,4'-bis(α.

α-dimethylbenzyl)diphenylamine.

The antioxidant can be added during the reaction in which the copolyether ester is formed.

In fact, the antioxidant is preferably present at any point during the process where the poly(alkylene oxide) glycol is exposed to high temperatures, such as about 100° C. or higher.

The antioxidant can be added at any stage of the process, even after the production of the copolyetherester is complete.

The properties of the copolyether esters can also be modified by adding various common organic photonic agents such as carbon black, silica gel, alumina, clay and chopped glass fibers. By weight unless otherwise specified.

The invention is further illustrated by the following examples.

Example 1 Preparation of Copolyetherester A copolyetherester is prepared by placing the following materials in a stirred flask equipped with a distillation column.

Polytetramethylenecol, 38.5 parts Number average molecular weight approximately 975 14-Butanediol 36.5 parts Dimethyl terephthalate 60. o part 4.4'-bis (α,
β-1,05 parts dimethylbenzyl) diphenylamine catalyst 2.1 parts Paddle cut (paddl) adapted to the inner diameter of the flask
Place a stainless steel stirrer with a cutter approximately 1/8 inch (0.32 cm) from the bottom of the flask and begin stirring.

Place the flask in a 160°C oil bath and stir for 5 minutes, then add the catalyst.

While slowly increasing the temperature to 250°C for 1 hour,
Methanol is distilled out from the reaction mixture.

When the temperature reaches 250° C., the pressure is gradually reduced to 0.3 MHg within 20 minutes.

The polymer was heated to 250℃/0.3 mmHg Kh3
Stir for 5 minutes.

The resulting viscous molten product is nitrogen (contains no water or oxygen).
Remove from flask in atmosphere and allow to cool.

This polymer has an intrinsic viscosity of 0.1 g/d in m-cresol.
The concentration of Cl is 1.40 at 30°C, and the Shore D hardness is 55.

EXAMPLES 2-7 AND COMPARATIVE EXAMPLES Stretching of Copolyether Ester A 1 inch x 6 inch (2.5 cm 25-0,33 questions) cut out from the calendar film.

The specimen is stretched 400% at a first temperature.

After being stretched by 400%, the specimen has a length five times its original length.

adjusting the stretched specimen to a second temperature, which is a heat setting temperature, while maintaining the stretching force to maintain 400% elongation;
The specimen is then adjusted to a third temperature that releases the stretching force.

Examples 2-7 in the table below show the physical properties of the copolyetheresters after stretching using various stretching, heat setting and release temperatures.

The comparative example is outside the scope of the present invention in that the specimen was stretched without being subjected to heat setting.

A comparison of Examples 2-7 with the comparative example reveals the beneficial effects of the heat setting treatment on modulus and tensile strength.

Example 8 Fabrication of a V-belt A 5-foot (1,52
The copolyetherester prepared in Example 1 is extruded into a mold having a length of m).

The cavity of this mold has a trapezoidal cross-section perpendicular to its long axis, and the long parallel side has a length of 0.87 mm.
At 5 inches (2,22 cm), both angles adjacent to the long parallel sides are 71° and the distance between the parallel sides is 0.59 inches (1,50 on).

The mold is cooled to room temperature and the molded product is taken out.

The molded article is stretched to 400% of its original length at room temperature.

In this operation, a molded article with a length of 5 feet (1.52 m) will be stretched to a length of 25 feet (7.62 m).

11 while maintaining this stretching force, and 350
Exposure to a temperature of 177° C. for 30 minutes, then cool to room temperature and remove the stretching forces from the stretched (orientated) molding.

Select the 3 feet (0.91 m) part of the stretch-molded product,
Cut both ends at a 45° angle to form a V-belt.

Touch the sides of both ends of the cut part and press 450 to 550 below (
232-288° C.) for a sufficient period of time to weld near the edges of the copolyetherester.

Separate the welded ends from the hot surface and immediately hold the ends together to allow the molten material to solidify.

When cool, trim the joint to remove excess material.

Embodiments of the invention are as follows.

1. Formed from a drawn copolyether ester elastomer consisting essentially of repeating long chain ester units and short chain ester units linked head-to-tail by ester bonds, the long chain ester units having the formula

Claims (1)

[Scope of Claims] 1. Formed from a drawn copolyether ester elastomer consisting essentially of repeating long chain ester units and short chain ester units linked head-to-tail by ester bonds, the long chain ester units having the formula %. and the short chain ester unit has the formula O II II II -0DO-CRC, where G has a molecular weight of about 400 to 6000 and a carbon to oxygen ratio of about 2.0 to 4.3. A certain poly (
R is a divalent group remaining after removing a terminal hydroxyl group from a dicarboxylic acid (alkylene oxide) glycol, R is a divalent group remaining after removing a carboxyl group from a dicarboxylic acid having a molecular weight of about 300 or less, and D is a molecular weight is the divalent group that remains after removing the hydroxyl group from a diol of about 250 or less, provided that the short chain ester units are present in the range of about 15 to 95 M% by weight of the copolyether ester elastomer, and the LOGA9 ether ester elastomer is (A) the elastomer has a length of at least 3
(B) the elastomer at a temperature of about 150 to 20 degrees below the melting point of the copolyether ester (83 to 11°C).
) at a low temperature and (C) stretching the elastomer.
at least 100'F (
A power transmission belt formed from an oriented copolyetherester elastomer that has been oriented by cooling to a lower temperature (56° C.) and (D) recovering an oriented copolyetherester elastomer having improved properties.