JPH04252220A - Production of polyurethane elastomer having excellent load resistance - Google Patents

Abstract

PURPOSE:To obtain the subject elastomer useful for roller, etc., usable under severe condition compared with conventional roller by reacting a specific compound to a prepolymer obtained by compounding a specific tolylene diisocyanate and a bifunctional polyol at a specific ratio. CONSTITUTION:The objective elastomer can be produced by reacting (A) tolylene diisocyanates composed of a mixture of 50-70wt.% of the 2,4-isomer of tolylene diisocyanate and 50-30wt.% of the 2,6-isomer with (B) a bifunctional polyol (preferably having an average molecular weight of 850-2,000) at an NCO/OH equivalent ratio of 1.2-3.0 and reacting the obtained prepolymer with (C) 4,4'- methylene-bis(2-chloroaniline).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane elastomer having good load resistance. More specifically, tolylene diisocyanate with a specific composition (hereinafter referred to as TD
The present invention relates to a method for producing a polyurethane elastomer with excellent load resistance, which is obtained by obtaining a prepolymer from a polyol and a polyol and curing the prepolymer with a specific diamine.

0002

[Prior Art] Conventionally, thermosetting polyurethane elastomers have strong tensile properties and excellent abrasion resistance, so they are used in industrial rolls such as paper manufacturing and steel, forklift tires, and trolleys. Used for casters, roller coaster wheels, roller skates, etc. However, the conditions for use of materials used for these purposes are often extremely harsh. For this reason, among various elastomers, thermosetting polyurethane elastomers with excellent physical properties are widely used. These polyurethane elastomers are usually cylindrical and are used while being rotated under load. This means that compression and relaxation are repeatedly applied to the elastomer, and if this load exceeds the allowable weight of the elastomer, the elastomer may become deformed and unable to return to its original shape. It will not be able to withstand high loads and will generate heat, causing melting of the resin or destruction due to bursting. There has been a demand for polyurethane elastomers used in such situations to have high strength and good load resistance. The thermosetting polyurethane elastomer used to improve these problems is generally a so-called prepolymer obtained by reacting a stoichiometric excess of TDI with a polyol, and a curing agent for the prepolymer. It is obtained by reaction with an aromatic diamine called The reason why diisocyanates other than TDI are not used in these reactions is that in combination with a curing agent, high hardness,
This is because high strength cannot be obtained, and furthermore, the reaction is too fast or too slow. The polyurethane elastomer obtained by reacting such a TDI prepolymer with an aromatic diamine has a weight ratio of 2,4-TDI in an isomer mixture of 2,4-TDI and 2,6-TDI as a TDI component. However, 80-100% of them are used. However, sufficient physical properties have not been obtained with elastomers having such compositions. Generally, if the ratio of 2,4-TDI is less than 80%, the TDI prepolymer will react too quickly with aromatic diamines, and the approximate time for casting will be limited. Because of its short pot life, it was rarely used. Moreover, if the content ratio of 2,6-TDI exceeds 20%, a large amount of free TDI tends to remain in the prepolymer obtained by reacting with a polyol. This problem arises because the two NCO groups in 2,6-TDI have equal reactivity. For these reasons, TDI used in prepolymers has a mixing ratio of isomers of 2,
6/2,4=100/0 to 80/20 has been preferably used. Conventionally, there was no awareness of the load capacity of 2,6-TDI, and 2,6-TDI, which is easy to perform casting operations, was used.
The reason is that sufficient physical properties have not been obtained because the isomer mixture ratio has been used at a low weight content of TDI. Thermosetting urethane elastomer for steel manufacturing or
When used as a roll for papermaking, this roll is used under high linear pressure (pressure applied per unit length) in a state in which it is pressed against a roll made of metal or the like facing it. If you want to continue rotating under such high linear pressure for a long time, or if you want to continue operating with higher linear pressure, or if you want to operate at a faster rotation speed, It is necessary to use an elastomer that is strong and has excellent load-bearing properties. In this case, unless an elastomer with excellent load resistance is used, if continued use under high load conditions, the elastomer may melt or even break due to internal heat accumulation. In addition, when used for trolley casters, forklift tires, roller skate rolls, etc., if the load exceeds the allowable capacity of the elastomer, the elastomer may break, burst, or chip, and may not function properly. It's gone. Conventionally, this has been solved by increasing the number of casters, increasing the hardness of the casters, or increasing the size of the casters. However, these methods have the drawbacks of being too expensive, impairing ride comfort and quietness, and increasing the size of the vehicle itself. Due to their lack of load bearing capacity,
Alternatively, it was desired to solve various problems encountered due to the small load capacity.

0003

[Problems to be Solved by the Invention] As a result of extensive research in order to improve the conventional drawbacks, the present inventors have developed a prepolymer obtained by reacting a specific TDI with a polyol component as a diisocyanate component. It was discovered that the load carrying capacity could be significantly improved by reacting with 4,4'-methylene-bis(2-chloroanisone) (hereinafter abbreviated as MOCA), leading to the present invention.

0004

[Means for Solving the Problem] That is, the present invention provides 2,4- and 2,6-isomer mixtures of TDI.
- 50-30% by weight of isomers, 50-30% of 2,6-isomers
Using 30% by weight of TDI, a bifunctional polyol was added to the diisocyanate at an NCO/OH equivalent ratio of 1.2 to 3.0.
This is a method for producing a polyurethane elastomer with excellent load resistance, characterized in that it is obtained by reacting a prepolymer obtained by reacting with MOCA.

2,4-TDI and 2,6-TDI are used as diisocyanates for synthesizing the prepolymer of the present invention.
The mixing ratio of the isomers is 50/50 to 70/30. If the mixing ratio of 2,4 TDI is less than 50%, there will be too much free TDI, which is not favorable for the working environment. In addition, when reacting with MOCA, problems arise such as the pot life, which is the time available for casting operations, becomes too short, making it impossible to pour the resin into a predetermined mold. Moreover, if the mixing ratio of the 2,4-isomer is more than 70%, a polyurethane elastomer with excellent load resistance cannot be obtained.

The type and average molecular weight of the bifunctional polyol that can be used in the present invention are appropriately selected depending on issues such as the hardness of the final elastomer and the viscosity of the prepolymer. things are used. A more preferable average molecular weight is 850 to 2,000.

Representative polyether and polyester polyols as polyols used in the present invention are poly(alkylene ether) glycols such as poly(ethylene ether) glycol, poly(propylene ether) glycol and poly(tetramethylene ether). Glycols, and cyclic ethers such as ethylene oxide, propylene oxide, trimethylene oxide and tetrahydrofuran, aliphatic diols such as ethylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,2 - polyethers produced using propylene glycol and 1,3-propylene glycol as initiators. It is also possible to use mixtures of the polyethers mentioned above.

Polyester diols such as poly(ethylene adipate) diol, poly(propylene adipate) diol, poly(ethylene-propylene adipate) diol, poly(butylene adipate) diol, poly(hexamethylene adipate) diol, etc., and ethylene glycol, Copolyester diols produced by polycondensing propylene glycol, adipic acid, such as poly(tetramethylene-ethylene adipate) diol, poly(1,4-butylene-propylene adipate) diol, and poly(1,4-butylene -ethylene-propylene adipate) diol, etc., but are not limited thereto. Examples of other polyester diols include caprolactone and/or dicarboxylic acids such as succinic acid, malonic acid, pimelic acid, sebacic acid and suberic acid, among others, and diols such as ethylene glycol, 1,2-propanediol, 1
, 3-propanediol, 2,2-dimethyl-1,3-
Propanediol, 1,4-butanediol, 1,5-
It also includes those produced by polymerization with pentanediol, 1,6-hexanediol, etc. It is also possible to use mixtures of the above polyester diols.

TDI for obtaining the prepolymer of the present invention
The NCO/OH equivalent ratio in the reaction of and polyol is 1
．． It is in the range of 2 to 3.0, preferably 1.4 to 2.6. The reaction conditions are a reaction temperature of 50°C to 100°C.
The duration is 1 to 5 hours.

[0010] Furthermore, the reaction conditions for the prepolymer and MOCA to obtain the polyurethane elastomer are NH2/
The molar ratio of NCO is 0.90 to 1.00, and the heat curing conditions are 110°C to 125°C for 3 hours to 12 hours.

[0011]

[Operation] The present invention contains 50 to 70% by weight of 2,4-TDI,
By using a specific TDI containing 50 to 30% by weight of 2,6-TDI, we have created a polyurethane elastomer with excellent durability in terms of load-bearing capacity under conditions of repeated compression and relaxation. Obtainable. Moreover, within this range, the pot life will not become too short and the casting operation will not be possible. This makes it possible to overcome the problem of insufficient load bearing capacity.

0012

[Example] Regarding the present invention, according to an example and a comparative example,
The present invention will be explained in more detail, but the present invention is not limited thereto. In Examples and Comparative Examples, all "parts" mean "parts by weight", and all "%" mean "% by weight".
means.

Example 1 Weighed 222.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=65/35 into a glass flask;
Poly(tetramethylene ether) glycol (hereinafter referred to as PTG) with an average molecular weight of 1000 was melted at about 60°C.
))) Add 777.7 grams in small portions, approximately 75°
C. While stirring and mixing, heat and react for about 3 hours. The prepolymer obtained after about 3 hours contains 4 reactive NCOs.
．． It was a prepolymer containing 2%.

After weighing 300 grams of the prepolymer, the temperature was adjusted to 75°C, and the ratio with MOCA was NH2/NCO.
= 0.95 molar ratio, quickly mixed and stirred with a predetermined amount of MOCA dissolved at 120°C, and preheated in a hot air dryer at 120°C for compression testing. It was poured into a mold and heated at 120°C for 10 hours. 10
After a period of time, it was removed from the mold and aged at room temperature for 7 days to obtain a polyurethane elastomer. The results are shown in Table 1.

Example 2 Weighed 175.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=55/45 into a glass flask,
PT with an average molecular weight of 2000 melted at about 60°C
Add 827.7 grams of G, heat to about 75°C while stirring and mixing, and react for about 3 hours. The prepolymer obtained after about 3 hours was a prepolymer containing 5.0% reactive NCO. Example 1 using the prepolymer
A polyurethane elastomer was obtained in the same manner as above. The results are shown in Table 1.

Comparative Example 1 Weighed 222.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=100/0 into a glass flask,
PT with an average molecular weight of 1000 melted at about 60°C
Add 777.7 grams of G, heat to about 75°C while stirring and mixing, and react for about 3 hours. The prepolymer obtained after about 3 hours was a prepolymer containing 4.2% of reactive NCOs.

After weighing 300 grams of the prepolymer, the temperature was adjusted to 75°C, and the ratio with MOCA was NH2/NCO.
= 0.95 molar ratio, quickly mixed and stirred with a predetermined amount of MOCA dissolved at 120°C, and preheated in a hot air dryer at 120°C for compression testing. It was poured into a mold and heated at 120°C for 10 hours. After 10 hours, this was removed from the mold and aged at room temperature for 7 days to obtain a polyurethane elastomer. The results are shown in Table 1.

Comparative Example 2 Weighed 222.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=80/20 into a glass flask,
PT with an average molecular weight of 1000 melted at about 60°C
Add 777.7 grams of G, heat to about 75°C while stirring and mixing, and react for about 3 hours. The prepolymer obtained after about 3 hours was a prepolymer containing 4.2% of reactive NCOs. Comparative Example 1 using the prepolymer
A polyurethane elastomer was obtained in the same manner as above.

Comparative Example 2 Weighed 175.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=100/0 into a glass flask,
PT with an average molecular weight of 2000 melted at about 60°C
Add 827.7 grams of G, heat to about 75°C while stirring and mixing, and react while maintaining this state for about 3 hours. The prepolymer obtained after about 3 hours was a prepolymer containing 5.0% reactive NCO. A polyurethane elastomer was obtained using the prepolymer in the same manner as in Comparative Example 1. The results are shown in Table 1.

Comparative Example 4 Weighed 222.3 grams of TDI in a ratio of 2,4-TDI/2,6-TDI=45/55 into a glass flask,
PT with an average molecular weight of 1000 melted at about 60°C
Add 777.7 grams of G, heat to about 75°C while stirring and mixing, and react for about 3 hours. The prepolymer obtained after about 3 hours was a prepolymer containing 4.2% of reactive NCOs. Comparative Example 1 using the prepolymer
A polyurethane elastomer was obtained in the same manner as above. The results are shown in Table 1.

[0021]

[Table 1]

Notes to Table 1) Load Resistance Test The test pieces prepared in each example were subjected to repeated compression and relaxation tests using a device capable of performing repeated compression tests under a constant load. In this experiment, a hydraulic servo manufactured by Saginomiya Seisakusho was used. In this test, the load ranged from 500 kg to 100 kg.
The load is increased in increments of 20,000 g, and compression is repeated 20,000 times at each load, and the load required to break is measured.

2) Reactivity test (POT LIFE) After weighing 300 grams of each of the prepolymers of Examples 1 to 2 and Comparative Examples 1 to 4, the temperature was adjusted to 75°C, and NH2
/NCO=0.95 molar ratio at 120°C
The mixture was quickly mixed and stirred with a predetermined amount of MOCA, poured into a 300cc glass container pre-heated at 120°C, and quickly submerged in an oil bath whose temperature was controlled at 120°C. , the viscosity is 500 with a B-type viscometer.
Measure the time until reaching 00cp.

[0024]

Effects of the Invention: The thermosetting polyurethane elastomer obtained by reaction-curing with MOCA using the prepolymer having a TDI isomer weight ratio according to the present invention has a
It has excellent load resistance compared to MOCA curing type polyurethane elastomer with isomer weight ratio. Also MO
In the reaction process with CA, if the isomer ratio of TDI according to the present invention is within the range, the pot life is 5 minutes or more, and time for handling can be secured. The present invention makes it possible to use polyurethane elastomer rolls, rollers, casters, etc. under more severe conditions (larger loads) than in the past.

Claims (1)

[Claims] [Claim 1] 2,4- of tolylene diisocyanate
And in the 2,6-isomer mixture, tolylene diisocyanate containing 50 to 70% by weight of the 2,4-isomer and 50 to 30% by weight of the 2,6-isomer is used, and the difunctional polyol is added to the diisocyanate. with an NCO/OH equivalent ratio of 1.
The prepolymer obtained by reacting with 2 to 3.0 and 4,4
1. A method for producing a polyurethane elastomer having excellent load-bearing properties, which is obtained by reacting with '-methylene-bis(2-chloroaniline).