JPH0544784A - Heat resistant toothed belt - Google Patents

Abstract

PURPOSE:To improve the extent of heat resistance in a toothed belt by using urethane elastomer consisting of a prepolymer to be obtained with diisocyanate as polyisocyanate. CONSTITUTION:A polyisocyanate ingredient is added to a polyol ingredient and reacted as long as one hour at a temperature 85 deg.C under a nitrogen stream, forming it into a urethane polymer with a terminal isocyanate group. This polymer is kept at a temperature of 80 deg.C, and a hardener is added and heated as long as 120 minutes at 110 deg.C, through which a hardening reaction is completed. Polyurethane elastomer obtained like this is used for a back part 1 and a tooth form part 2 of a toothed belt which is made up of a core wire 3 interposed between these elements 1 and 2 and canvas 4 covered on the tooth form part 2. Therefore the toothed belt causes no slackening over the back part 1 and, what is more, excellent in heat resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant toothed belt suitable for use in a high temperature environment such as a belt around an automobile engine.

[0002]

2. Description of the Related Art Conventionally, toothed belts are often manufactured from chloroprene rubber in the past, but, for example, in the automobile field, in recent years, downsizing of parts and transmission of power transmission have been performed. With the increase in the number of axes, the temperature of the atmosphere in which the toothed belt is used remarkably rises, and the belt made of chloroprene rubber has insufficient heat resistance. Therefore, in recent years, for example, as described in JP-A-51-36247 and JP-A-60-121341, a toothed belt using chlorosulfonated polyethylene rubber as a back rubber or tooth rubber, Kaisho 60-172
No. 749, a toothed belt using a sulfur-containing cross-linking composition of hydrogenated nitrile rubber, and a peroxide of hydrogenated nitrile rubber as described in JP-A-64-87937. Toothed belts and the like using a cross-linking composition have been proposed, but it is hard to say that their heat resistance is still sufficient.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in view of the above situation, and as a result, have found that the above technical problems can be solved by adopting the following technical means, and thus the present invention is completed. I arrived. That is, the heat-resistant toothed belt of the present invention comprises paraphenylene diisocyanate (PPD1).
And a polyurethane elastomer obtained by reacting a prepolymer composed of a hydroxyl group-terminated polyol with a curing agent was used.

The hydroxyl group-terminated polyols are polyester type polyols, polyether type polyols,
It is supposed to be composed of one or more polycarbonate-based polyols. The polyester polyol is, for example, a condensate of a polycarboxylic acid and a low molecular weight polyol and has a molecular weight of 500 to 10,000. Specifically, poly (ethylene adipate) (hereinafter "PE
A)), poly (diethylene adipate) (hereinafter referred to as "PDA"), poly (propylene adipate)
(Hereinafter referred to as “PPA”), poly (tetramethylene adipate) (hereinafter referred to as “PBA”), poly (hexamethylene adipate) (hereinafter referred to as “PHA”), poly (neopenethylene adipate) (hereinafter referred to as “PNA”). ]),
Polyol consisting of 3-methyl-1,5-pentanediol and adipic acid, random copolymer of PEA and PDA, random copolymer of PEA and PPA, PEA and PB
A random copolymer of A, a random copolymer of PHA and PNA, or a caprolactone polyol obtained by ring-opening polymerization of ε-caprolactone, β-methyl-δ-valerolactone obtained by ring-opening with ethylene glycol Polyols etc. (These all have a molecular weight of 500
It is preferably 1 to 10,000), and each is used alone or in combination. Furthermore, examples of the polyester-based polyol include a copolymer of at least one of the following acids and at least one of glycols.

Acids : terephthalic acid, isophthalic acid, phthalic anhydride, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid (mixture), paraoxybenzoic acid, trimellitic anhydride, ε-caprolactone, β-methyl-δ-valerolactone glycol : ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, polyethylene glycol, polytetramethylene glycol, 1 , 4-Cyclohexanedimethanol, pentaerythritol, 3-methyl-1,5-pentanediol As the polyether polyol, for example, alkylene oxide (eg, ethylene oxide, propylene oxide) is an active hydrogen compound. Those provided by ring-opening addition polymerization using a polyhydric alcohol (for example, diethylene glycol) as an initiator, specifically polypropylene glycol (PPG), polyethylene glycol (PEG), a copolymer of propylene oxide and ethylene oxide, and the like. Be done. Further, it is given by cationic polymerization of tetrahydrofuran and has a molecular weight of 500 to
It is 5,000. Specifically, it is polytetramethylene ether glycol (PTMG), and tetrahydrofuran is a copolymer with another alkylene oxide. Specifically, it is a copolymer of tetrahydrofuran and propylene oxide, tetrahydrofuran and ethylene. Examples thereof include copolymers with oxides (all of which preferably have a molecular weight of 500 to 10,000), and they may be used alone or in combination.

As the polycarbonate-based polyol,
Conventionally known polyol (polyhydric alcohol) and phosgene,
Obtained by condensation with chloroformic acid ester, dialkyl carbonate or diallyl carbonate, various molecular weights are known. Particularly preferred as such a polycarbonate polyol is 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, or 1,5-pentanediol as the polyol. It has a molecular weight of about 500 to 10,000. For example, a polycarbonate diol represented by the following general formula 1

[0007]

[Chemical 1]

[0008] can be mentioned. The structure of the polyol portion of the polycarbonate-based urethane prepolymer used in the present invention includes polycarbonate-based polyols such as those described above, random copolymers of polycarbonate-based polyols and polycaprolactone-based polyols, and random polycarbonate-based polyols and polyester-based polyols. Examples thereof include a copolymer or a mixture of a polycarbonate-based polyol, a polycaprolactone-based polyol and a polyester-based polyol, which may be used alone or in combination.

The method for producing the urethane prepolymer by reacting one or more of the above-mentioned polyols with para-phenylene diisocyanate is not particularly limited, and examples thereof include reaction temperature, reaction time, presence or absence of solvent, etc. It can also be carried out by a known method including. In order to obtain the urethane elastomer used in the present invention, the urethane prepolymer obtained as described above may be mixed with a curing agent to cure the urethane prepolymer.

The curing agent that can be used is not particularly limited and may be any of those generally used in the past when curing a urethane prepolymer to produce a urethane elastomer. Examples thereof include polyol compounds and polyamine compounds. As the polyol compound,
It is not particularly limited, primary polyol, secondary polyol, 3
Any of the graded polyols may be used. Specifically, ethylene glycol, 1,3-propanediol, 1,4
-Butanediol, 1,5-pentanediol, 1,6
-Hexanediol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 2,5- Hexanediol, 2,4-hexanediol, 2-ethyl-1,3-hexanediol, cyclohexanediol, 2-ethyl-2- (hydroxymethyl) -1,3-
Propane diol etc. are mentioned. The polyamine compound is not particularly limited, such as diamine, triamine, and tetraamine, and any of primary amine, secondary amine, and tertiary amine can be used. Specifically, aliphatic amines such as hexamethylenediamine, 3,3′-dimethyl-
Alicyclic amines such as 4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis-2-chloroaniline, 2,2'3,3'-tetrachloro-4,4'-diaminophenylmethane, 4, Aromatic amines such as 4′-diaminodiphenyl, 2,4,6-tris (dimethylaminomethyl) phenol and the like can be mentioned. These curing agents may be used alone or in combination of two or more.

A method for mixing the above-mentioned curing agent and the urethane prepolymer obtained as described above to cure the urethane prepolymer is not particularly limited, and for example, for the urethane prepolymer. It can also be carried out by an ordinary method including the mixing ratio of the curing agent, the curing temperature, the curing time, and the like. The polyurethane elastomer used in the present invention may contain additives and the like. Additives that can be used in the present invention are plasticizers, flame retardants, fillers, stabilizers, colorants and the like.

Examples of the plasticizer include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), tricresyl phosphate (TC).
P), chlorinated paraffin, etc. can be used. As the flame retardant, phosphoric acid esters such as tris- (β-chloropropyl phosphate, tris-dichloropropyl phosphate, trischloroethyl phosphate), bromine compounds such as dibromoneopentyl glycol, tribromoneopentyl alcohol and the like can be used.

As the filler, for example, glass fiber, carbon black, calcium carbonate, talc, kaolin, zeolite, diatomaceous earth, perlite, permiculite, titanium dioxide and the like can be used. As the stabilizer, conventionally used antioxidants, ultraviolet absorbers, light stabilizers, hydrolysis inhibitors and the like can be used.

The antioxidant acts as a radical chain inhibitor and a peroxide decomposer, and the former includes sterically hindered phenols and aromatic amines. As a radical chain inhibitor, butylated hydroxytoluene, tetrakis [methylene.3. (3'.5'-di.tbutyl-4hydroxyphenyl) propionate] methane, n.octadecyl-β- (4'.hydroxy-3) "-5"
t-butylphenyl) propionate, 1,3,5 tris (4.t-butyl-3hydroxy-2,6dimethylbenzyl) isocyanuric acid, triethylene glycol bis 3
(2-t-butyl-4-hydroxy-5-methylphenyl) propionate or the like can be used.

As the peroxide decomposing agent, 4,4'thiobis (6-t-butyl.m.cresol, dilauryl.thiodipropionate, distearylthio.dipropionate, thiophenylphosphite and the like can be used. As a UV absorber, salicylic acid-based phenyl salicylate, Pt-butylphenyl salicylate, benzophenone-based 2,4-di-hydroxybenzophenone, 2-
Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, benzotriazole-based 2 (2'-hydroxy-5'-methylphenyl) benzotriazole, 2 (2'-hydroxy-
3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-3 ',
5'-di-t-aminophenyl) benzotriazole,
Siare acrylate type ethyl-2-cyano-3,5-
Diphenyl acrylate, 2 (2'-hydroxy-5 '
-T-octylphenyl) benzotriazole and the like can be used.

As the UV screen, pigments such as carbon black and zinc white can be used. As a light stabilizer, there is a hindered amine. Hindered amines include bis (1,2,2,2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate
6,6-pentamethyl-4-piperidyl, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate of succinate,
Poly [[6- (1,1,3,3-tetramethylbutyl)
Imino-1,3,5-triazine-2,4-diyl]
[(2,2,6,6-tetramethyl-4-piperidyl)
Imino] hexamethylene [[2,2,6,6-tetramethyl-4-piperidyl) imino]], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalon Acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) or the like can be used.

As a hydrolysis inhibitor, carbodiimide type stavaxol-1, PCD (Bayer Co.), hexamethylenetetramine, azodicarbonamide, 4-t
-Butylcatechol and the like can be used. The method for producing the urethane prepolymer by reacting the hydroxyl group-terminated polyol and para-phenylene diisocyanate is not particularly limited, for example, reaction temperature,
It can be carried out by a known method including the reaction time, the presence or absence of a solvent and the like.

It is necessary to react the organic polyisocyanate and the active hydrogen-containing compound so that the prepolymer thus obtained has an isocyanate group content of 1 to 20% by weight. When the isocyanate group content of the obtained prepolymer exceeds 20% by weight and becomes large, the amount of free paraphenylene diisocyanate increases and the storage stability of the urethane prepolymer becomes poor.

If it is less than 1% by weight, the urethane prepolymer has a low isocyanate group content and the pot life becomes too long, resulting in poor productivity. The structure of the heat-resistant toothed belt of the present invention, as a canvas,
For example, one made of nylon, aramid, or the like, preferably one laminated with polyethylene resin on one side is used, and the core wire is made of, for example, glass, aramid, steel, or the like. It is not limited to.

The heat-resistant toothed belt according to the present invention can be manufactured by a conventionally known conventional method. That is, use a nylon cloth laminated on one side with polyethylene resin, wrap it so that the polyethylene resin layer is in contact with the toothed cylindrical mold, and spirally place a tensile body of "Kevlar" (Dupont aramid fiber) on it. Wound into a mold, put in a mold, a curing agent is added to the prepolymer of the present invention in the space between the mold member and the cylindrical mold, and the mixture is press-filled by a known press-fitting molding method, heated at 110 ° C. for 120 minutes, and then urethane. After the resin was crosslinked, the tooth mold was removed from the cylindrical mold and cut into a belt having a predetermined width to produce a toothed belt.

[0021]

The present invention takes the above technical means, and by adopting the above-mentioned respective constituents, it is possible to provide a toothed belt having excellent heat resistance. That is, the heat-resistant toothed belt of the present invention using the urethane elastomer made of a prepolymer obtained by using paraphenylene diisocyanate as the polyisocyanate exhibits excellent heat resistance in a running test under a high temperature environment. This makes it suitable for use as a timing belt in a high temperature automobile engine room.

[0022]

EXAMPLES Examples 1 to 5 Heat-resistant toothed belts of the present invention were produced as follows. The polyurethane elastomer was obtained by the following procedure. First, a polyisocyanate component (hereinafter referred to as (2)) is added to a polyol component (hereinafter referred to as (1)) and reacted at 85 ° C. for 1 hour under a nitrogen stream to obtain a urethane prepolymer having a terminal isocyanate group. obtain.

Isocyanate group (NCO) content of the resulting urethane prepolymer (shown below), and
The viscosity at 80 ° C. (shown below) was measured. The viscosity of the prepolymer is Haake rotary viscometer / Rotobisco R
It calculated | required using V-12. 100 parts by weight of the urethane prepolymer obtained as described above was kept at 80 ° C., a curing agent (hereinafter referred to as (3)) was added, and the mixture was kept at 110 ° C. for 120 minutes.
Heated to complete the curing reaction. (Example 1) (1) Polyol component The average molecular weight (refers to the number average molecular weight; hereinafter the same) is 2,0.
100 parts by weight of 44 of the copolymer polyol of polycarbonate and caprolactone (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Nipporan 982R) was used. (2) Polyisocyanate component 15.6 parts by weight of paraphenylene diisocyanate (= PPDI, manufactured by DuPont) was used. (3) Curing agent 12.9 parts by weight of 2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane (= TCDAM, manufactured by Ihara Chemical Industry Co., Ltd.) was used.

Each measurement result: Isocyanate group (NCO) content: 3.59% (theoretical value: 3.60%) Viscosity at 80 ° C .: 14,680 cps A sheet-shaped molded product having the above composition was obtained by the same method. The hardness (JIS A) was 89. (Example 2) (1) Polyol component 80 parts by weight of a polycarbonate polyol having an average molecular weight of 1,908 (Nipporan 980R, manufactured by Nippon Polyurethane Industry Co., Ltd.) and a polyester-based polyol having an average molecular weight of 2,087 (Kuraray stock) 20 parts by weight of CLAPOL L2010, manufactured by the company, was blended and used. (2) Polyisocyanate component 16.5 parts by weight of PPDI was used. (3) Curing agent 12.7 parts by weight of TCDAM was used.

Each measurement result: Isocyanate group (NCO) content: 3.53% (theoretical value: 3.71%) Viscosity at 80 ° C .: 22,930 cps When a sheet-like molded product having the above composition was obtained by the same method The hardness (JIS A) was 90. (Example 3) (1) Polyol component 80 parts by weight of a polycarbonate polyol having an average molecular weight of 1,908 (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Nipporan 980R) and a polyester polyol having an average molecular weight of 1,950 (Kuraray stock) 20 parts by weight of CRAPOL P2010 (trade name, manufactured by the company) was blended and used. (2) Polyisocyanate component 16.7 parts by weight of PPDI was used. (3) Curing agent 13.3 parts by weight of TCDAM was used.

Each measurement result: Isocyanate group (NCO) content: 3.68% (theoretical value: 3.75%) Viscosity at 80 ° C .: 15,080 cps When a sheet-like molded product having the above composition was obtained by the same method The hardness (JIS A) was 88. (Example 4) (1) Polyol component Polycaprolactone polyol having an average molecular weight of 1,975 (manufactured by Daicel Chemical Industries, Ltd., trade name Praxel 2)
20 N) was used in 100 parts by weight. (2) Polyisocyanate component 16.2 parts by weight of PPDI was used. (3) Hardener 3.1 parts by weight of 1,4-butanediol (= 1,4BD, manufactured by Kanto Chemical Co., Inc.) and 2-ethyl-2- (hydroxymethyl) -1,3-propanediol (= TMP (Manufactured by Kanto Kagaku Co., Ltd.) 0.4 part by weight.

Each measurement result: Isocyanate group (NCO) content: 3.66% (theoretical value: 3.66%) Viscosity at 80 ° C .: 2,320 cps When a sheet-shaped molded product having the above composition was obtained by the same method. The hardness (JIS A) was 90. (Example 5) (1) Polyol component 80 parts by weight of a polycarbonate polyol having an average molecular weight of 1,996 (Nipporan 980R, manufactured by Nippon Polyurethane Industry Co., Ltd.) and polytetramethylene ether glycol having an average molecular weight of 1,986 ( Hodogaya Chemical Co., Ltd., trade name PTG2000) 20 parts by weight was used by blending. (2) Polyisocyanate component 16.1 parts by weight of PPDI was used. (3) Hardener 13.0 parts by weight of TCDAM was used.

Each measurement result: Isocyanate group (NCO) content: 3.60% (theoretical value: 3.63%) Viscosity at 80 ° C .: 23,190 cps A sheet-shaped molded product having the above composition was obtained by the same method. The hardness (JIS A) was 82. A toothed belt having a structure as shown in FIG. 1 was produced by using each of the polyurethane elastomers in the back part and the tooth profile part. This toothed belt is composed of a back portion 1, a tooth profile portion 2, a core wire 3 interposed therebetween, and a canvas 4 attached to the tooth profile portion 2. The RU type belt has a tooth pitch of 9.525 mm. , Number of teeth 92, length 34.5 inches, width 0.
75 inches. Comparative Example A toothed belt using a sulfur-containing cross-linked composition of hydrogenated nitrile rubber was produced as follows.

The hydrogenated nitrile rubber composition is 100 parts by weight of hydrogenated nitrile rubber (Zetpol: manufactured by Zeon Corporation), 40 parts by weight of carbon black, 10 parts by weight of a plasticizer,
Zinc white 5 parts by weight, stearic acid 1 part by weight, antioxidant 2
Parts by weight, 2.5 parts by weight of a vulcanization accelerator, and 0.5 parts by weight of sulfur were compounded, and kneaded by a known means and method using a Banbury mixer, a roll, etc., to obtain a rubber sheet.

The canvas is prepared by using the rubber composition described above in 2-3.
Adhesion-treated nylon cloth was used, which was dissolved in 5 times the amount of solvent, and then phenol resin was added and dissolved in 20 to 30% of the rubber composition to prepare rubber paste, and the nylon cloth was dipped and dried. As the tensile body, Kevlar was used as described above. Using the hydrogenated nitrile rubber composition for the back and the tooth profile, a toothed belt having the structure shown in FIG. 1 was produced by a conventionally known ordinary method.

That is, after winding the canvas on the toothed cylindrical mold, the tensile body is spirally wound, the rubber sheet is further wound, and pressure molding and vulcanization are performed in a pressure vessel. Then, it was removed from the mold and cut into a predetermined width to produce a toothed belt. Next, the toothed belt of the present invention and the conventional toothed belt were subjected to a running test under a high temperature environment (150 ° C.) using an apparatus as shown in FIG.

In FIG. 2, 5 is a RU type (number of teeth = 20) driving pulley, and 6 is a RU type (number of teeth = 40) non-driving pulley. Then, the initial tension of the toothed belt 7 spanned between the driving pulley 5 and the non-driving pulley 6 is adjusted to 15 Kgf by the φ52 mm tensioner pulley 8, and the driving pulley 5
Was rotated at a rotation speed of 6000 rpm, and the toothed belt 7 was run. After the start of running, the running time until the back of the toothed belt cracked was measured. The results are shown in Table 1.

[0033]

[Table 1]

As is clear from Table 1, the toothed belt using the hydrogenated nitrile rubber composition shown as a comparative example,
Although the back 1 is cracked in a short time and is inferior in heat resistance, the toothed belts using the polyurethane elastomers shown in Examples 1 to 5 are heat-resistant without cracking in the back 1 in a short time. It will be excellent.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a specific configuration of a heat resistant toothed belt of the present invention.

FIG. 2 is an explanatory view of an apparatus for carrying out a running test of the heat resistant toothed belt of the present invention in a high temperature environment.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical location C08G 18/76 NFH 8620-4J (72) Inventor Nobuyuki Yokoyama 172 Ikezawa, Yamatokoriyama City, Nara Unituta Co., Ltd. Ceremony company Nara factory (72) Inventor Satoshi Nakane 172 Ikezawa-cho, Yamatokoriyama city, Nara Unituta Co., Ltd. Nara factory

Claims (1)

[Claims] 1. Para-phenylene diisocyanate, polyester-based polyol, polyether-based polyol,
A heat-resistant toothed belt comprising a polyurethane elastomer obtained by blending a prepolymer composed of one or more polycarbonate-type polyols with a curing agent.