KR101682505B1 - Polyurethane elastomer for nonair-type tire and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a urethane for a non-pneumatic tire, and more particularly to a urethane used for manufacturing a spoke of a non-pneumatic tire.
In order to solve the above problems, the present invention provides a polyurethane casting elastomer having a lower permanent compression strain without damaging other physical properties and processing advantages, including a polycaprolactone polyol, a polycarbonate polyol Or a mixture thereof. ≪ / RTI >
The urethane according to the present invention is capable of preventing permanent compression deformation when the permanent extrusion reduction ratio is greatly improved to be used for spokes of a non-pneumatic tire. Accordingly, the polyurethane casting elastomer using the polyol of the present invention has remarkably improved permanent compression strain, has the same processing advantages as those of the conventional art, and maintains at least the same level of physical properties as those of the prior art, It can be used as pneumatic tire member.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyurethane casting elastomer for a non-pneumatic tire member and a method of manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a urethane for a non-pneumatic tire, and more particularly to a urethane used for manufacturing a spoke of a non-pneumatic tire.

New non-pneumatic tires have been developed to replace existing rubber pneumatic tires. As shown in FIG. 1, a non-pneumatic type tire is formed with a spoke portion having a shape similar to a spoke of a wagon on a tire wheel and a tread portion of a tire contacting the ground on the outer surface of the spoke portion. Frictional resistance characteristics are important because the tread portion comes into contact with the ground and friction occurs, while the spoke portion should have a good compressive strain so as to prevent compression deformation of the tire. Accordingly, there is a continuing need for a new urethane resin that can withstand compression deformation when used in a tire, and a manufacturing method thereof.

Without environment-friendly tires and technology development, it is difficult to adapt to environment regulations and high oil prices, and even in China, which is now the world's second-largest automobile market as well as developed countries such as the US, EU and Japan, Due to the strengthening of international environmental regulations, advanced nations prohibit Nitrosoamine additive in rubber manufacturing and prohibit the use of extender oils containing PAHs (Poly-Aromatic Hydrocarbons) Is undergoing environmental improvement. In order to overcome these problems, it is necessary to develop a new concept of lightweight high-performance tires that can replace existing rubber pneumatic tires. Recently, advanced companies are developing new technologies using new elastic materials. At the same time, we are trying to secure energy savings by simplifying the tire production process, improving tire durability and improving recyclability. At the same time, advanced companies are improving the performance of each part of tires to reduce Rolling Resistance We have developed tires to prepare for environmental regulations and are also developing recycling technologies for used tires.

Global tire companies have been leading the eco-friendly tire market by developing new concepts that are not based on existing technologies. Michelin and others have developed low-emission lightweight polyurethane pneumatic tires and wheel assemblies.

Polyurethane casting elastomers are well known as tough materials in high demand in a variety of applications. This material is simpler in production process than rubber material, and has high elasticity, low tan value at high temperature and excellent abrasion resistance, so it is suitable as non-pneumatic tire material. U.S. Patent No. 5,605,657 discloses an industrial solid tire suitable for high unloaded roads having cast polyurethane tires thereon produced by the batch method.

Polyurethanes are materials prepared using polyisocyanates, mostly diisocyanates, polyols, mostly diols, and short-chain organic compounds having hydroxyl or amino end groups.

The polyurethane can be produced by: firstly, an NCO prepolymer method in which a polyol and a polyisocyanate having a stoichiometric excess are reacted in advance to form a prepolymer having an NCO group, followed by chain extension reaction with a short chain organic compound having a hydroxyl or amino end group ; The second is produced by casting divided into two main processes: a one-shot process in which a polyol and a short-chain organic compound having a hydroxyl or amino end group are mixed together and then reacted with a polyisocyanate.

The reason that the prepolymer process generally provides a good product is that some of the heat of reaction is dissipated in the prepolymer stage to lower the exothermic properties of the actual polymer synthesis. This has a favorable effect on the rate of increase of the molecular weight and shows the processing advantage by keeping the casting time long.

Another reason is that the use of MDI-based (4,4'-isomer isomer: about 42 ° C) system lowers the melting point of, for example, the polyisocyanates associated with prepolymerization. The MDI can be liquid at room temperature by prepolymerization (NCO prepolymer), which is substantially easier to process as compared to when it is essentially solid, and also does not significantly slow down the undesirable dimerization of the monomeric polyisocyanate do.

A problem to be solved by the present invention is to provide a urethane resin suitable for manufacturing spokes of a non-pneumatic tire.

Another object of the present invention is to provide a process for producing a urethane resin suitable for producing spokes of a non-pneumatic tire.

Another object of the present invention is to provide a spoke of a non-pneumatic tire made of urethane having excellent permanent compression characteristics.

In order to solve the above-mentioned problems, the present invention provides a polyurethane casting elastomer having a low permanent compressive strain without deteriorating other physical properties and processing advantages, including a polycaprolactone polyol, a polycarbonate polyol, Characterized in that it is produced by crosslinking a polyurethane prepolymer containing the mixture.

In the present invention, the polyurethane prepolymer is prepared by reacting a polyisocyanate compound with a polyol compound comprising a polycaprolactone polyol, a polycarbonate polyol, or a mixture thereof to form a urethane group.

In the present invention, the polyol compound may be used alone or in combination with other known polyols such as polyether polyol, polyester polyol, acrylic polyol, Can be mixed and used. In this case, it is preferable to use a polyol mainly composed of polycaprolactone polyol, polycarbonate polyol, or a mixture thereof in order to prevent deterioration of physical properties of the polyol compound, more preferably, polycaprolactone More preferably at least 70% by weight, even more preferably at least 80% by weight, and most preferably at least 90% by weight, based on the weight of the polyol, polyol, polycarbonate polyol, It is good.

In the present invention, the polycaprolactone polyol may be prepared by ring-opening polymerization with a caprolactone monomer and a polycarbonate polyol is a glycol, for example, 1,6-hexylene glycol and an organic carbonate, For example, it may be prepared by the action of diphenyl carbonate, diethylcarbonate or ethylene carbonate. The polycaprolactone polyol and the polycarbonate polyol may be commercially available and used.

In the present invention, the molecular weight of the polycaprolactone polyol and / or the polycarbonate polyol is advantageous in the strain rate, while preventing deterioration of hardness and abrasion resistance, which are conventional physical properties, and exhibits superior characteristics in terms of tensile strength and elastic modulus It is preferable that the polyol is a polyol having a number average molecular weight of 250 or more. Molecular weights between approximately 500 and 6,000 are preferred, and molecular weights between approximately 650 and 3,000 are most preferred. However, the molecular weight of the high molecular weight polyol may be as high as 10,000, or as low as 250. Additionally, low molecular weight glycols and triols having a molecular weight between 60 and 250 may be included.

In the present invention, the polyisocyanate compound is preferably a diisocyanate compound such that diphenylmethane diisocyanate is used so that cross-linking is carried out after preparing the prepolymer. Diphenylmethane diisocyanate is superior in physical properties and processability to aliphatic diisocyanates such as hexamethylene diisocyanate or isophorone diisocyanate, has a lower vapor pressure than toluene diisocyanate, and is less susceptible to health, Is superior in stability to a prepolymer prepared from para-phenyl diisocyanate or naphthalene diisocyanate.

In the present invention, the prepolymer is preferably a prepolymer having an NCO end so as to be suitable for the production of an elastomer by a casting method. The OH prepolymer has a higher molecular weight than the prepolymer at the NCO end and is therefore not suitable for the production of a mold elastomer because of its high viscosity. In the practice of the present invention, the NCO end prepolymer has an NCO range of from 9.0 to 12.0, more preferably from 9.2 to 11.5, even more preferably from 9.4 to 11.0, and most preferably from 9.6 to 10.2. If the NCO value is too high, the hardness phase having a high concentration of urethane groups may become large in the casting elastomer, and the strain rate may be greatly increased due to rearrangement of the hard phase during stretching or compression. When the NCO value is excessively low, Physical properties such as elastic modulus, abrasion performance and the like can be greatly reduced.

The NCO terminated prepolymer is stored by cooling to a low temperature (storage temperature) for the purpose of reacting with the chain extender immediately after their preparation or for the purpose of the chain extender in a later step. The synthetic route through the prepolymer is advantageous in that a portion of the reaction heat is already generated during synthesis of the prepolymer to reduce the exothermicity of substantial polymer synthesis. This shows a beneficial effect on the rate of molecular weight increase and permits a longer casting time to exhibit processing advantages. In one particularly preferred embodiment of the preparation of a polyurethane casting elastomer by the prepolymer process, the prepolymer is first degassed by applying a reduced pressure at room temperature or elevated temperature and then stirred with the chain extender at normal temperature.

In the process according to the invention, the prepolymer is heated to a temperature preferably between 60 [deg.] C and 110 [deg.] C with stirring and degassed under vacuum. The chain extender and / or cross-linking agent is then optionally added in liquid form, typically after heating to a temperature at which its melting point exceeds 5 ° C. The reaction mixture is cast in a preheated mold (preferably 90 ° C to 120 ° C) and cured at 90 ° C to 140 ° C for about 16 to 24 hours.

The curing agent, that is, the chain extender, usable with the prepolymer can be selected from a variety of conventional well-known organic diamine or polyol materials. Preferred materials are low melting point solids or liquids. Specifically preferred materials are alcohol based chain extender and / or crosslinking agents and blends thereof having a melting point of less than 140 < 0 > C. These alcohol-based chain extender and / or cross-linking agents are currently used in the industry as curing agents for polyurethanes. The choice of the curing agent is generally based on the requirements of reactivity, the requirements of the properties for the particular application, the requirements of the process conditions and the casting time required. Known catalysts can be used with the curing agent. Preferred curing agents are aliphatic triols such as 1,4-butanediol, hydroquinone-bis-hydroxyethyl ether, aliphatic diols such as 1,4-cyclohexanedimethanol, and trimethylol propane. The most preferred materials are aliphatic diols such as 1,4-butanediol, hydroquinone-bis-hydroxyethyl ether, and 1,4-cyclohexanedimethanol.

It is also possible to use auxiliary substances and additives which are preferably incorporated, such as catalysts, stabilizers, UV stabilizers, hydrolytic stabilizers, emulsifiers, and dyes and color pigments.

Examples of catalysts are trialkylamines, diazabicyclooctanes, tin dioctanoate, dibutyltin dilaurate, N-alkyl morpholine, lead, zinc, calcium or magnesium octanoate and the corresponding naphthenates and p - Nitrophenate.

Examples of stabilizers are Bronsted acid and Lewis acid, such as hydrochloric acid, benzoyl chloride, organic mineral acids such as dibutyl phosphate, and adipic acid, malic acid, succinic acid, tartaric acid or citric acid.

Examples of UV stabilizers and hydrolytic stabilizers are 2,6-dibutyl-4-methylphenol and sterically hindered carbodiimides.

Dyes which may be incorporated are dyes having a Zeritivinov active hydrogen atom, i.e. capable of reacting with an NCO group.

In one aspect, the present invention provides a polyurethane elastomer according to the present invention, which can be used as an elastic molded article produced by a casting method and as a non-pneumatic tire member for an electric vehicle, for example, The spoke of the tire is a cured product of a prepolymer comprising a polycaprolactone polyol, a polycarbonate polyol, or a mixture thereof. The cured product has a permanent compression ratio of 10 to 25% after curing.

The urethane according to the present invention is capable of preventing permanent compression deformation when the permanent extrusion reduction ratio is greatly improved to be used for spokes of a non-pneumatic tire. Thus, the polyurethane casting elastomer using the polyol of the present invention has significantly improved permanent compression strain, has the same processing advantages as those of the prior art, and at the same time maintains the same physical properties at least at the level of the prior art, It can be used as pneumatic tire member.

1 is a view showing a structure of a non-pneumatic tie-up according to an embodiment of the present invention.

Example

Hereinafter, the present invention will be described in detail with reference to examples. The following examples are intended to illustrate the present invention and not to limit it, and the scope of the present invention is defined in the claims.

Test Methods:

[Hardness] ASTM D2240

[Tensile strength] ASTM D412

[Elongation at break] ASTM D412

[300% elastic modulus] ASTM D412

[Permanent Compression Ratio] ASTM D395

[Tan 隆] ASTM D5992

[Abrasion resistance] ASTM D5963

[Rebound elastic modulus] ASTM D2632

[ Example  One]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, , 100 parts by weight of polycaprolactone glycol 1 having a number average molecular weight of 2,000 was rapidly stirred to polymerize prepolymer 4. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of prepolymer 4 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Example  2]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, , And 100 parts by weight of polycaprolactone glycol 2 having a number average molecular weight of 2,000 were rapidly stirred to polymerize prepolymer 5. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of the prepolymer 5 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Example  3]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, , 100 parts by weight of polycaprolactone glycol 3 having a number average molecular weight of 2,000 was rapidly stirred to polymerize prepolymer 6. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of the prepolymer 6 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Example  4]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, , And 100 parts by weight of polycaprolactone glycol 4 having a number average molecular weight of 2,000 were rapidly stirred to polymerize prepolymer 7. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of the prepolymer 7 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Example  5]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, 100 parts by weight of a polycarbonate glycol having a number average molecular weight of 2,000 was rapidly stirred to polymerize prepolymer 8. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of the prepolymer 8 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Comparative Example  One]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, And 100 parts by weight of polytetramethylene ether glycol having a number average molecular weight of 2,000 were rapidly stirred to polymerize prepolymer 1. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of prepolymer 1 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Comparative Example  2]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, And 100 parts by weight of polyethylene adipate glycol having a number average molecular weight of 2,000 were rapidly stirred to polymerize prepolymer 2. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of prepolymer 2 was degassed at 90 占 폚 under vacuum while slowly stirring until the bubbles disappeared. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

[ Comparative Example  3]

60.5 parts by weight of 4,4'-isomer of 4,4'-diphenylmethane diisocyanate (Cosmonate PH) of 98.5% by weight was heated in a stirring flask under nitrogen to 70 ° C, defoamed under vacuum for 30 minutes, And 100 parts by weight of polyethylene propylene adipate glycol having a number average molecular weight of 2,000 were rapidly stirred to polymerize prepolymer 3. The reaction was allowed to proceed for 1 hour and the physical properties were measured. (See Table 1)

100 parts of prepolymer 3 was degassed at 90 占 폚 under vacuum while slowly stirring until bubbles were removed. This was then stirred with 9.75 parts of 1,4-butanediol preheated to 30 DEG C for 30 to 50 seconds at 300 to 500 rpm and the reacted uniform melt was cast into a mold preheated to 110 DEG C with dimensions corresponding to the test specimens . The melt was then heated at < RTI ID = 0.0 > 110 C < / RTI > for 24 hours and the mechanical properties listed in Table 2 were measured.

The casting time of the prepolymer according to the invention at the same prepolymer temperature (starting temperature) and the same NCO content is not only equal to the casting time of the system not according to the invention, but also exhibits improved physical properties at tensile strength, 300% elasticity , Indicating an apparent improvement in permanent compression ratio.

division NCO Range
(% NCO) Brookfield Viscosity,
Poise @ 80 ° C Appearance
@ 25 ° C Pot Life,
min Color, Gardner Specific
Gravity Prepolymer 1 9.85-10.2 780 Solid 3-4 0-2 1.11 Prepolymer 2 9.85-10.2 650 Solid 3-4 0-2 1.16 Prepolymer 3 9.85-10.2 1,000 Solid 3-4 0-2 1.15 Prepolymer 4 9.85-10.2 610 Solid 3-4 0-2 1.13 Prepolymer 5 9.85-10.2 520 Solid 3-4 0-2 1.15 Prepolymer 6 9.85-10.2 460 Solid 3-4 0-2 1.14 Prepolymer 7 9.85-10.2 550 Solid 3-4 0-2 1.15 Prepolymer 8 9.60-10.2 2800 Solid 2-3 0-2 1.21

Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Example 4 Example 5 % NCO 10 10 10 10 10 10 10 10 Index (NCO / OH) 110 110 110 110 110 110 110 110 Hardness (shore A) 96 95 96 95 93 94 95 97 Tensile Strength (MPa) 28.7 33.8 27.7 30.7 34.3 32.4 31.8 34.7 Elongation (%) 580 630 580 520 560 670 620 308 300% modulus of elasticity (MPa) 16.4 18 15.9 15.6 15.5 14.1 15.7 27.6 Permanent Compression Ratio (%) 35 41 31 18 21 24 19 11 Tanδ (@ 0 C) 0.1 0.32 0.19 0.2 0.19 0.19 0.2 0.30 Tanδ (@ 60 ° C) 0.04 0.06 0.05 0.04 0.05 0.04 0.04 0.09 Abrasion resistance (g) 0.06 0.11 0.10 0.08 0.11 0.10 0.12 0.09 Resilience (%) 59 36 43 40 43 40 47 34

The casting elastomers according to the invention also exhibit their advantages in terms of their mechanical properties:

For example, when the casting elastomer prepared from prepolymer 1 (Table 2, Comparative Example 1) is compared with the casting elastomer prepared from prepolymer 8 (Table 2, Example 5) (all prepolymers contain 10.0% by weight of NCO Having the same NCO value), the system according to the present invention has a very high 300% elastic modulus. When the casting elastomer (Table 2, Comparative Example 2) prepared from Prepolymer 2 was compared with the casting elastomer prepared from Prepolymer 5 (Table 2, Example 2) (both prepolymers had the same NCO of 10.0 wt% NCO Value), the system according to the present invention has better tensile strength and rebound resilience.

The system according to the invention exhibits a prepolymer viscosity and casting time which are similar to those of the system not according to the invention and exhibit a unique combination of favorable properties with respect to mechanical and mechanical-dynamic properties.

Claims (10)

A polyurethane prepolymer comprising a polycaprolactone polyol, a polycarbonate polyol, or a mixture thereof is crosslinked in a mold, wherein the NCO% range of the prepolymer is from 9.0 to 12.0, cured with an aliphatic diol, Wherein the compression ratio of the tire is 10 to 25%. The non-pneumatic tire spoke member according to claim 1, wherein the polyurethane prepolymer is formed by reacting a polyisocyanate compound with a polyol compound comprising a polycaprolactone polyol, a polycarbonate polyol, or a mixture thereof to form a urethane group . delete The non-pneumatic tire spoke member according to claim 2, wherein the polyol compound is 60-100 wt% of a polyol selected from the group consisting of a polycaprolactone polyol, a polycarbonate polyol, and a mixture thereof. delete 3. The non-pneumatic tire spoke member according to claim 2, wherein the polyisocyanate compound is diphenylmethane diisocyanate. delete delete delete delete

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