KR101288295B1 - Manufacturing method of polyurethane having excellent fatigue resistance and polyurethane manufactured thereby - Google Patents

Abstract

The present invention relates to a process for producing a polyurethane having excellent fatigue resistance and improved storage stability and mechanical properties by synthesizing a prepolymer by reacting two or more NCO group-containing diisocyanates having different reactivities separately with polyol, The obtained polyurethane is provided.

Description

[0001] The present invention relates to a method for producing a polyurethane excellent in fatigue resistance and a polyurethane produced by the method,

The present invention relates to a process for producing a polyurethane excellent in fatigue resistance and a polyurethane produced therefrom. More specifically, the present invention relates to a process for producing polyurethane excellent in fatigue resistance by preparing two or more polyurethane prepolymers from two or more diisocyanates having different reactivities in separate polymerization vessels and mixing them in one polymerization vessel, ≪ / RTI >

Polyurethanes are generally produced by the reaction of a polyol having an active hydroxyl group (-OH) with an isocyanate group having an isocyanate group (-NCO), and can be used in a variety of applications including synthetic rubber, synthetic fibers, adhesives, paints, automobile bumper rubber, It is a polymer substance used for the purpose.

In addition, polyurethane is a block copolymer composed of two segments of two different types. That is, the polyurethane is composed of a soft segment made of polyol and a hard segment made of isocyanate.

The hard segment has a glass transition temperature higher than room temperature and has a rigid property and is related to properties such as the tensile strength of the polyurethane due to the formation of a physical cross-linking between hydrogen bonds or van der Waals bonds between the segments. The soft segment has a flexible molecular structure such as a viscous or rubbery property and has a glass transition temperature lower than room temperature, thus giving the polyurethane elastic properties such as rubber.

The polyurethane has a phase-separated structure due to the thermodynamic non-affinity of these two segments. The physical properties of the polyurethane may vary depending on the degree of phase separation and phase separation of the two segments.

In particular, the fatigue resistance of polyurethanes depends on the proportion of soft segments directly affected by external forces. When a large number of hard segments are dispersed in a region on the soft segment, the friction between the molecules is large and the speed at which the soft segment reacts to the external force is delayed. Therefore, the greater the degree of phase separation between the hard segment and the soft segment, the better the fatigue resistance.

Accordingly, various studies have been made to produce polyurethane excellent in chemical and physical properties by controlling the degree of phase separation and phase separation depending on the production method, temperature, kinds and amounts of polyol and isocyanate, and the like.

An object of the present invention is to produce a polyurethane having excellent fatigue resistance and improved storage stability and mechanical properties at low cost.

The present invention relates to a process for preparing a polyisocyanate compound, which comprises reacting two or more NCO group-containing diisocyanates having different reactivities in a separate polymerization reactor in a molar ratio of polyol and NCO: OH of 3 to 6: 1 to obtain two or more prepolymers; And mixing the two or more prepolymers obtained in the above step in one polymerization vessel and adding one equivalent or more of a polyol, a chain extender, a defoaming agent and a foaming agent based on the free NCO group of the prepolymer do.

The slow-reacting diisocyanate may be 60 to 80 parts by weight per 100 parts by weight of the total diisocyanate, and the fast diisocyanate may be 20 to 40 parts by weight per 100 parts by weight of the total diisocyanate.

The less reactive diisocyanate may be MDI, and the more reactive diisocyanate may be NDI.

The chain extender may be 9 to 18 parts by weight, the defoaming agent may be 0.05 to 0.1 parts by weight, and the blowing agent may be 0.4 to 1 part by weight based on 100 parts by weight of the total polyol.

The reaction may be carried out at a temperature of 80 to 130 ° C.

The present invention also provides a polyurethane produced by the above production method.

According to the present invention, it is possible to produce polyurethane having favorable storage stability and mechanical properties as well as excellent fatigue resistance under favorable economic conditions.

Fig. 1 schematically shows an example of a process for producing a polyurethane according to the present invention.
Fig. 2 schematically shows an example of a conventional method for producing polyurethane.
3 is a transmission electron microscope (TEM) photograph of the polyurethane obtained in Example 1 and Comparative Example 2 of the present invention.

The present invention relates to a process for preparing a polyisocyanate compound, which comprises reacting two or more NCO group-containing diisocyanates having different reactivities in a separate polymerization reactor in a molar ratio of polyol and NCO: OH of 3 to 6: 1 to obtain two or more prepolymers; And mixing the two or more prepolymers obtained in the above step in one polymerization vessel and adding one equivalent or more of a polyol, a chain extender, a defoaming agent and a foaming agent based on the free NCO group of the prepolymer do.

Generally, the polyurethane is produced by an ONE-SHOT method in which a polyisocyanate is reacted with a mixture of a polyol, a polyol, a chain extender, a catalyst, a foaming agent, and an antifoaming agent at one time, an OH-terminated prepolymer or polyol reacted with an excess polyol and a polyisocyanate, Is reacted with an excess amount of NCO-terminated prepolymer. In the general prepolymer method (hereinafter referred to as M-blend method), a part of a polyol is added to a polymerization vessel, and a certain proportion of one or more diisocyanates are added together while stirring to form a prepolymer.

However, in the method of the present invention (hereinafter referred to as the P-blend method), two or more different isocyanate base prepolymers are synthesized in different polymerization tanks and then mixed in one polymerization tank to prepare polyurethane, A polyurethane having improved mechanical properties such as storage stability can be obtained.

The diisocyanate having low reactivity among the two or more diisocyanates is preferably 60 to 80 parts by weight per 100 parts by weight of the total diisocyanate and 20 to 40 parts by weight per 100 parts by weight of the total diisocyanate. Within this range, the storage stability of the polyurethane can be improved.

As the diisocyanate, those commonly used in the production of polyurethane can be used. Examples of the diisocyanate include diphenyl methane-4,4-diisocyanate (MDI), naphthalene-1,5-diisocyante (NDI), toluene diisocyanate (TDI) hexamethylene diisocyanate) may be used.

More specifically, in the present invention, MDI may be used as a low-reactivity diisocyanate. MDI (diphenyl methane-4,4-diisocyanate) is not suitable for the production of polyurethane which requires a high level of mechanical strength because it causes severe deformation and abrasion due to dynamic load. However, since it is inexpensive and has good storage stability, general polyurethane .

On the other hand, NDI can be used as a highly reactive diisocyanate. NDI (naphthalene-1,5-diisocyante) is relatively expensive and has poor storage stability. However, since it has excellent mechanical properties and fatigue properties due to its excellent reactivity, it is difficult to manufacture polyurethane requiring high mechanical strength and fatigue resistance Is used.

The polyol refers to a polyfunctional alcohol having two or more OH groups in the molecule and can be classified into a polyether polyol and a polyester polyol. Examples of the polyol include polypropylene glycol, polytetramethylene glycol, poly [di (ethylene glycol) adipate], and polycaprolactone diol, and the like But is not limited thereto.

In the present invention, a polyhydric alcohol having 2 to 3 OH groups as the polyol can be used, and the number average molecular weight of the polyhydric alcohol is preferably 10,000 or less, particularly preferably 1,000 to 5,000.

In the present invention, the polyol is reacted with the diisocyanate in an NCO: OH molar ratio of 3 to 6: 1 in the first step and, in the second step, at least 1 equivalent, preferably at least 1 equivalent but not more than 3 equivalents based on the free NCO group of the prepolymer Respectively.

The chain extender is used to obtain a polymer having a high molecular weight by linking chains while reacting with an isocyanate as a lower molecular weight alcohol or amine to form a urethane group. The chain extender may be selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,3 Propanediol, 1,4-butanediol, 2-methylpentanediol, 1,5-pentanediol, 3-methylpentanediol, But are not limited to, 3-methyl pentane diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol (1,4 1,2-propylenediamine, 1,3-proylenediamine, isophoronediamine, isophoronediamine, and 1,3-propanediol diol. Diamines such as ethylenediamine, N-methylpropylene-1,3-diamine and N, N'-dimethylehtylenediamine, Or mixed. It said, the 1,4-butanediol or ethylene glycol is preferred.

The content of the chain extender may be 9 to 18 parts by weight per 100 parts by weight of the polyol. If the content of the chain extender is within the above range, polyurethane having an appropriate hardness can be produced, which is preferable.

If necessary, additives such as a defoaming agent, a foaming agent, a catalyst, a filler, a foam stabilizer, a flame retardant, an antioxidant, an ultraviolet absorber and a pigment may be used. The content of the additives is not particularly limited, Can be used as part.

Since the polyurethane polymerization reaction must proceed promptly and not violently, the production of the polyurethane of the present invention is preferably carried out at a temperature of 80 to 130 캜.

The present invention also provides a polyurethane produced by the process for producing a polyurethane of the present invention. The polyurethanes prepared by the process of the present invention have excellent storage stability and fatigue resistance and have good mechanical properties.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. It will be understood that various modifications and changes may be made to the present invention without departing from the spirit and scope of the invention as defined in the following claims.

Example

(Example 1: P-blend method)

Two polymerization vessels maintained at 120 DEG C to 130 DEG C under a nitrogen stream were prepared, and 60 parts by weight of polydiethylene glycol adipate having a number average molecular weight of 2,000 was stirred in each polymerization vessel for 1 hour. Then, 31.25 parts by weight of MDI was added to one polymerization vessel and 7.35 parts by weight of NDI was added to the other polymerization vessel. After completion of the addition, each reaction mixture was heated at 90 占 폚 for 1 hour with stirring to obtain an isocyanate-terminated MDI base prepolymer and an NDI base prepolymer. Each of the obtained prepolymers was mixed in one polymerization vessel, and 40 parts by weight of polydiethylene glycol adipate, 13.5 parts by weight of 1,4-butanediol, 0.05 part by weight of a defoaming agent and 0.5 part by weight of a foaming agent were added, , And the mixture was foamed at 3,000 rpm for 30 seconds to be put into a mold having a thickness of 6 mm which had been heated to 80 to 120 ° C in advance. After 25 minutes, the polyurethane was removed from the mold and aged at 110 ° C for 16 hours to produce a polyurethane.

(Example 2: P-blend method)

Two polymerization vessels maintained at 120 ° C to 130 ° C under a nitrogen stream were prepared, and 60 parts by weight of polydiethylene glycol adipate having a number average molecular weight of 2,000 was stirred in each polymerization vessel for 1 hour. 37.5 parts by weight of MDI was added to one polymerization vessel and 10.5 parts by weight of NDI was added to the other polymerization vessel. After completion of the addition, each reaction mixture was heated at 90 占 폚 for 1 hour with stirring to obtain an isocyanate-terminated MDI base prepolymer and an NDI base prepolymer. Each of the obtained prepolymers was mixed in one polymerization vessel, and 40 parts by weight of polydiethylene glycol adipate, 13.5 parts by weight of 1,4-butanediol, 0.05 parts by weight of an antifoaming agent and 0.5 part by weight of a foaming agent were added and placed in a plastic cup made of polyethylene And the mixture was foamed at 3,000 rpm for 30 seconds to be put into a mold having a thickness of 6 mm which had been heated to 80 to 120 ° C in advance. After 25 minutes, the polyurethane elastomer was removed from the mold and aged at 110 DEG C for 16 hours to prepare a polyurethane.

(Comparative Example 1)

60 parts by weight of polydiethylene glycol adipate having a number average molecular weight of 2,000 was stirred for 1 hour and 38.75 parts by weight of MDI was added to a polymerization vessel maintained at 70 DEG C to 80 DEG C under a nitrogen stream. After completion of the addition, the reaction mixture was heated at 90 DEG C for 1 hour under stirring to obtain an isocyanate-terminated prepolymer. 40 parts by weight of polydiethylene glycol adipate, 13.5 parts by weight of 1,4-butanediol, 0.05 parts by weight of defoamer and 0.5 part by weight of a foaming agent were added to the obtained prepolymer, and the mixture was foamed at 3,000 rpm for 30 seconds in a plastic cup made of polyethylene. And then placed in a mold having a thickness of 6 mm heated to 80 ° C to 120 ° C. After 25 minutes, the polyurethane elastomer was removed from the mold and aged at 110 DEG C for 16 hours to prepare a polyurethane having a hard segment mass ratio of 34%.

(Comparative Example 2: M-blend method)

60 parts by weight of polydiethylene glycol adipate having a number average molecular weight of 2,000 was stirred for 1 hour in a polymerization vessel maintained at 120 ° C to 130 ° C under nitrogen flow, and 31.25 parts by weight of MDI and 7.35 parts by weight of NDI were added together. After completion of the addition, the reaction mixture was heated at 90 DEG C for 1 hour under stirring to obtain an isocyanate-terminated prepolymer. 40 parts by weight of polydiethylene glycol adipate, 13.5 parts by weight of 1,4-butanediol, 0.05 parts by weight of defoamer and 0.5 part by weight of a foaming agent were added to the obtained prepolymer, and the mixture was foamed at 3,000 rpm for 30 seconds in a plastic cup made of polyethylene. And then placed in a mold having a thickness of 6 mm heated to 80 ° C to 120 ° C. After 25 minutes, the polyurethane elastomer was removed from the mold and aged at 110 DEG C for 16 hours to prepare a polyurethane.

(Comparative Example 3: M-blend method)

60 parts by weight of polydiethylene glycol diadiphate having a number average molecular weight of 2,000 was stirred for 1 hour in a polymerization vessel maintained at 120 ° C to 130 ° C under nitrogen flow, and 37.5 parts by weight of MDI and 10.5 parts by weight of NDI were added together. After completion of the addition, the reaction mixture was heated at 90 DEG C for 1 hour under stirring to obtain an isocyanate-terminated prepolymer. 40 parts by weight of polydiethylene glycol diadipate, 13.5 parts by weight of 1,4-butanediol, 0.05 parts by weight of a defoaming agent and 0.5 part by weight of a foaming agent were added to the obtained prepolymer, and the mixture was foamed at 3,000 rpm for 30 seconds in a plastic cup made of polyethylene Was placed in a mold having a thickness of 6 mm previously heated to 80 to 120 ° C. After 25 minutes, the polyurethane was removed from the mold and aged at 110 ° C for 16 hours to produce a polyurethane.

Composition (parts by weight) of monomers in polyurethane production division Example 1
(P-blend) Example 2
(P-blend) Comparative Example 1 Comparative Example 2
(M-blend) Comparative Example 3
(M-blend) Diisocyanate MDI 31.25 37.5 38.75 31.25 37.5 NDI 7.35 10.5 X 7.35 10.5 Chain extender 1,4-butanediol 13.5 13.5 13.5 13.5 13.5 Polyol Polydiethylene glycol adipate 100 100 100 100 100

(Evaluation test method)

(1) Glass transition temperature and melting point

The glass transition temperature and melting point of the obtained polyurethane elastomer were measured using a differential scanning calorimeter (DSC-4000) manufactured by Perkin Elmer with a measurement range of -60 ° C to 200 ° C and a temperature increase rate of 10 ° C / And a melting point were measured. The results are shown in Table 2 below.

(2) Fatigue resistance test

The fatigue resistance test of the obtained polyurethane elastomer was conducted by MTS systems Corp. Using the MTS 810 Material Test System. The measurement conditions were measured at a frequency of 2.0 Hz at 1.70 kN. The results are shown in Table 3 below.

(3) Mechanical properties

The hardness of the obtained polyurethane elastomer was measured by TIME Group Inc. Using a Digital Durometer (TH200). Tensile Strength and Elongation at Break% were measured by Tinius Olsen Ltd. (H5KT). ≪ tb > < TABLE > The results are shown in Table 4 below.

DSC measurement result division Synthesis method Hard Segment Weight percent (%) Tg (占 폚) Tm (占 폚) Example 1 P-blend 34.2 - 43.0 174.0 Example 2 P-blend 38.0 - 41.7 189.8 Comparative Example 1 - 34.3 - 49.7 142.0 Comparative Example 2 M-blend 34.2 - 46.5 151.4 Comparative Example 3 M-blend 38.0 - 45.2 162.1

Fatigue resistance measurement results division Synthesis method Hard Segment Weight percent (%) Compress fatigue / times Impact fatigue / times Example 1 P-blend 34.2 26,220 31,340 Example 2 P-blend 38.0 100,000 35,620 Comparative Example 1 - 34.3 6,110 8,920 Comparative Example 2 M-blend 34.2 8,213 11,680 Comparative Example 3 M-blend 38.0 35,620 10,720

Mechanical properties measurement results division Synthesis method Hard Segment Weight percent (%) Density (Kg / m) Shorea
hardness Tensile
Strength (Mpa) Elongation at break% Example 1 P-blend 34.2 502 89 4.7 376 Example 2 P-blend 38.0 502 93 4.8 376 Comparative Example 1 - 34.3 501 82 3.2 365 Comparative Example 2 M-blend 34.2 504 87 4.5 380 Comparative Example 3 M-blend 38.0 509 91 5.5 373

The reason why the Tm of the polyurethane produced by the method of the present invention (P-blend) is higher than that of the polyurethane produced by using the conventional M-blend is the same as that of the P-blend MDI / NDI It means that the hard segments made up of the blend and the chain extender are regularly aligned and the degree of phase separation between the hard segment and the soft segment is large.

In the results of the fatigue resistance measurement in Table 3, both the M-blend and the P-blend show a tendency to increase the fatigue resistance as the hard segment content increases. When the hard segment contents of the synthesized polyurethane are similar, The P-blend method is three times higher than the M-blend method.

In Table 4, the mechanical properties of the polyurethane elastomers synthesized by the M-blend method and the P-blend method similar to each other except for the polyurethane synthesized with the pure MDI of Comparative Example 1 are similar to each other. The reason for this is that the mechanical properties of M-blend and P-blend, which have the same composition, are similar because the tensile strength and elongation depend on the binding energy between the intermolecular attraction and the atom. Similarly, hardness of polyurethane of M-blend and P-blend is similar because hardness depends on hard segment and NCO / OH index.

Referring to FIG. 3, the white portion represents a soft segment and the black portion represents a hard segment. A comparison of the transmission electron microscope (TEM) photographs of Comparative Example 2 (M-blend) and Example 1 (P-blend) of FIG. 3 revealed that the polyurethane elastomer of Example 1 synthesized by the P- It is confirmed that the degree of phase separation of the hard segment is large.

From the above results, it can be seen that the polyurethane produced by the P-blend method of the present invention is more excellent in fatigue resistance than the polyurethane made by the conventional M-blend method because the degree of phase separation is large between the hard segment and the soft segment have. And because the polyurethanes were made with MDI / NDI (mass ratio) 82.7 / 17.3, polyurethanes with good fatigue resistance and mechanical properties were produced at a lower cost than polyurethane made from pure NDI, which is very expensive and poorly stored Can be seen.

Claims (6)

Two kinds of NCO group-containing diisocyanates having different reactivities selected from the group consisting of MDI, NDI, TDI and HMDI are reacted in a separate polymerization vessel in the molar ratio of polyol and NCO: OH of 3 to 6: 1 to prepare two kinds of prepolymer ; And
Mixing the two kinds of prepolymers obtained in the above step into one polymerization vessel and adding at least one equivalent of a polyol, a chain extender, a defoaming agent and a foaming agent based on the free NCO group of the prepolymer
≪ / RTI > The process according to claim 1, wherein the diisocyanate having a relatively low reactivity among the two diisocyanates is 60 to 80 parts by weight per 100 parts by weight of the total diisocyanate, and the relatively highly reactive diisocyanate is a 20 to 40 parts by weight of the polyurethane. The process for producing a polyurethane according to claim 1, wherein the diisocyanate having a relatively low reactivity is MDI and the diisocyanate having a relatively high reactivity is NDI among the two diisocyanates. The method for producing a polyurethane according to claim 1, wherein the chain extender is 9 to 18 parts by weight, the defoaming agent is 0.05 to 0.1 parts by weight, and the blowing agent is 0.4 to 1 part by weight based on 100 parts by weight of the total polyol. The process for producing a polyurethane according to claim 1, wherein the reaction is carried out at a temperature of 80 to 130 ° C. A polyurethane produced by the process of any one of claims 1 to 5.

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