KR101915080B1 - Urethane oligomer having low glass transition and manufacture of method for the same - Google Patents

Abstract

The present invention relates to a urethane oligomer having a low glass transition temperature, and a production method thereof. More specifically, the present invention relates to a method for producing a urethane oligomer which has a low glass transition temperature by using a branching agent containing ethylene oxide and a hydroxyl group in a molecule, and also exhibits outstanding physical properties at a low temperature. The present invention further relates to a urethane oligomer produced thereby.

Description

TECHNICAL FIELD The present invention relates to a urethane oligomer having a low glass transition temperature and a process for producing the urethane oligomer.

The present invention relates to a urethane oligomer having a low glass transition temperature and a process for producing the same. To a urethane oligomer having a low glass transition temperature using a branching agent containing ethylene oxide and a hydroxyl group in a molecule and capable of realizing excellent physical properties even at a low temperature and a urethane oligomer produced therefrom.

The urethane oligomer is formed through a urethane bond such as a polyol having two or more alcohol groups and a compound having two or more isocyanate groups or the like. It exhibits various and unique properties due to its high dimensional structure.

Urethane oligomers have soft segments and hard segments at the same time in the molecular structure, so that they can freely design the molecular length and are advantageous in realizing excellent physical properties. The soft segment and the hard segment can lower or increase the glass transition temperature, respectively, and cause a phase separation phenomenon in the molecule, which has an important influence on the molecular behavior.

Urethane oligomers are still required to have a lower glass transition temperature while increasing the molecular weight. That is, there is a demand for a technique for producing urethane oligomers that can realize the excellent physical properties of polyurethane while using the same monomer to lower the glass transition temperature without adjusting soft segment and hard segment. In order to improve the physical properties, there is a method of increasing the molecular weight by increasing the degree of crosslinking using a crosslinking agent, but still it is still insufficient to lower the glass transition temperature as compared with the increase of the molecular weight.

US Patent No. 5,278,257 discloses a branching agent. However, it is difficult to lower the glass transition temperature due to a small free volume, and in the case of diallylbisphenol A used, two allyl groups But has two disadvantages in that a side reaction in which the isocyanate reacts with the isocyanate is generated due to the presence of two hydroxyl groups capable of reacting with isocyanate. United States Patent No. 7,557,169 discloses that 2-allylphenol is used, but it is difficult to expect improvement in physical properties and has only a small effect of lowering the glass transition temperature since it has only one allyl group. In Korean Patent No. 1678419, 4,4 ', 4 "- (1,3,5-triazine-2,4,6-triyl) triphenol is used as a chain extension agent to provide a polymer having excellent thermal stability However, since the glass transition temperature is relatively low, it is limited to applications requiring low temperature characteristics. Japanese Patent Registration No. 2009-536233 relates to a hyperbranched polyurethane, wherein a material having a hydroxyl group or an amine group capable of reacting with two isocyanates is used as a hyperbranched agent and the brittleness is increased to a higher glass transition temperature, It is difficult to use it for applications such as an impact modifier that requires a temperature.

Therefore, it is possible to realize the advantages of excellent adhesive strength, bending strength, impact strength, heat resistance and flexibility of the original polyurethane, while efficiently lowering the glass transition temperature relative to a high molecular weight, Development is necessary.

U.S. Patent No. 5,278,257 (Oct. 10, 1994) United States Patent No. 7,557,169 (July 7, 2009) Korean Patent No. 10-1678419 (November 22, 2016) Japanese Patent Application Laid-Open No. 2009-536233 (2009.10.08)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a urethane oligomer having a high molecular weight and having a flexible structure in a molecular chain and having a glass transition temperature relatively lower than a molecular weight, And a method for producing the same.

One aspect of the present invention for achieving the above object is a process for producing a prepolymer having a linear structure having an isocyanate group at both ends by reacting a diisocyanate and a diol. The prepolymer includes a branching agent containing an ethylene oxide group and a hydroxyl group in the molecule And reacting the branched prepolymer with a capping agent to prepare an end capped polyurethane oligomer. The present invention also relates to a process for producing an urethane oligomer.

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the branching agent may have an ethylene oxide group and a hydroxyl group ratio (EO / OH) of 0.26 to 14 and a number average molecular weight of 150 to 2,000.

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the branching agent may be represented by the following general formula (1).

[Chemical Formula 1]

(Wherein, a, b and c are integers of 1 to 20).

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the capping agent may be a diallyl ether having one functional group reactive with isocyanate.

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the diisocyanate is at least one selected from the group consisting of isophorone diisocyanate, 1,6-hexamethylenediisocyanate, toluene diisocyanate and methyllindiphenyl isocyanate .

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the diol may have a number average molecular weight of 100 to 6,000, and may be at least one selected from an aliphatic ether diol and an ester diol.

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the prepolymer may have a number average molecular weight of 4,000 to 20,000.

In the process for preparing a urethane oligomer according to an embodiment of the present invention, the molar ratio of the diisocyanate to the diol may be 1.5 to 2.0.

Another aspect of the present invention relates to a urethane oligomer produced by the above-described process for producing a urethane oligomer.

The urethane oligomer according to an embodiment of the present invention may have a number average molecular weight of 5,000 to 70,000, a polydispersity index of 1.5 to 12, and a viscosity (25 ° C, Brookfield viscometer) of 100,000 to 1,000,000 cP.

The urethane oligomer according to an embodiment of the present invention has an advantage of excellent physical properties at a low temperature since it can effectively control the molecular weight and can induce a relatively low glass transition temperature while having a high molecular weight.

In addition, the urethane oligomer according to one embodiment of the present invention has the advantage of being applicable to various fields throughout the industry because it has low glass transition temperature and realizes excellent physical properties of polyurethane even at a low temperature.

1 shows a specimen according to KS M 3705 for measuring the compressive shear bond strength.
Figure 2 shows a specimen according to KS M 3729 for impact shear bond strength measurement.

Hereinafter, the urethane oligomer composition according to the present invention and the urethane oligomer prepared from the composition will be described in detail with reference to the accompanying drawings. Herein, the technical terms used have the meanings that are normally understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise specified. In addition, it is not intended to limit the scope of protection defined by the following claims.

Throughout the description describing the present invention, "including" an element means that it can include other elements, not excluding other elements unless specifically stated otherwise.

One aspect of the present invention is to provide a multi-functional branched structure having a skeleton of a urethane structure and using a branching agent containing an ethylene oxide group and a hydroxyl group in the molecule and introducing a mono-reactive substance capable of reacting at its terminals with a plurality of allyl groups and isocyanates, And particularly to a urethane oligomer excellent in low temperature characteristics by having a low glass transition temperature and a method for producing the urethane oligomer.

In detail, the process for preparing a urethane oligomer according to the present invention comprises the steps of reacting a diisocyanate and a diol to prepare a prepolymer having a linear structure having an isocyanate group at both ends thereof, a branching agent containing an ethylene oxide group and a hydroxyl group To form an end capped polyurethane oligomer by reacting the branched prepolymer with a capping agent.

As shown in the following Reaction Scheme 1, the process for preparing a urethane oligomer according to an embodiment of the present invention includes the steps of (1) preparing a prepolymer by reaction of a diisocyanate and a diol, introducing a branching agent containing an ethylene oxide group and a hydroxyl group And a capping step (3) of capping the end with introduction of a capping agent.

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In the present invention, the step of preparing the prepolymer is a step of preparing a prepolymer having a linear structure having an isocyanate group at both ends by stirring and reacting a mixture containing diisocyanate and diol.

The diisocyanate may be aromatic or aliphatic. Examples of the diisocyanate include, but are not limited to, isophorone diisocyante, 1,6-hexamethylene diisocyante, 4, 4'-methylenediphenyl diisocyanate, toluene diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, tetramethylene diisocyanate, tetramethylene diisocyanate, 4,4'-diisocyanato dicyclohexylmethane, methylpentamethylene diisocyanate, dodecamethylene diisocyanate, 1, 4'-diisocyanato dicyclohexylmethane, 1,4-diisocyanato cyclohexane, 4,4'- (2,2) (4,4'-diisocyanato dicyclohexylpropane- (2,2)), 1,4-diisocyanatobenzene, and p-toluenesulfonic acid. (P-isopropylidene diisocyanate) may be used. Preferably, the use of isophorone diisocyanate is advantageous in terms of the efficiency of prepolymer production.

The diol can be used without limitation as long as it is a substance having two or more hydroxy groups in the molecule. Specific examples thereof include polyether diols, polyester polyols, polypropylene glycols, polybutylene glycols, polytetrahydrofuran glycols and polycaprolactone polyols , And the like. Preferably, the use of polypropylene glycol is more efficient in terms of prepolymer production.

The diol is not particularly limited in the range of the hydroxyl group equivalent (molecular weight / number of hydroxy groups), but may be preferably 200 to 3,000, more preferably 500 to 2,000. When the above range is satisfied, it is effective in terms of the reaction efficiency and the branching efficiency of the prepared prepolymer, but this is a non-limiting example and is not limited to the above numerical range.

In the present invention, the molar ratio of the diisocyanate to the diol may be adjusted as needed. At this time, the molar ratio (diisocyanate / diol) of the diisocyanate and the diol may be 1.5 to 2.0, preferably 1.6 to 1.9. When the above range is satisfied, the properties and the reaction behavior of the ultimately obtained urethane oligomer are advantageous from the viewpoint of achieving the desired effect, but this is only a non-limiting example and is not limited to the above numerical range.

The step of preparing the prepolymer may further include a catalyst in the mixture to carry out the reaction. The catalyst may be any one selected from organotin compounds, organotitanium compounds and amine catalysts, preferably organotin compounds such as di-n-butylbis ( dodecylthio) tin and dibutyltin dilaurate may be used.

The prepolymer prepared in the preparation of the prepolymer has a linear structure, which is advantageous in that the final urethane oligomer has a flexible structure and has an effect of lowering the glass transition temperature.

Preferably, the prepared prepolymer may have a number average molecular weight of 4,000 to 20,000, more preferably 5,000 to 18,000. When the above range is satisfied, it is effective in securing a flexible chain structure through the branching step at the downstream and realizing a low glass transition temperature, but this is a non-limiting example and is not limited to the above numerical range.

Next, a branching agent is introduced into the prepared prepolymer to perform branching. At this time, the branching agent is characterized by containing an ethylene oxide group and a hydroxyl group in the molecule. When a branching agent containing ethylene oxide is used in the molecule, it can be reacted so that the length of the branch can be uniformly formed, and the molecular weight can be increased without increasing the glass transition temperature. Further, the branching agent can be lowered in branching degree as compared with the case where the branching agent is polymerized and polymerized at the time of polymerization of diisocyanate and diol, and can have a more flexible structure, so that it is more effective in realizing excellent physical properties at low temperatures.

The branching agent may preferably have a ratio of ethylene oxide to hydroxyl group (EO / OH) of 0.26 to 14, more preferably 0.26 to 10. When the above-mentioned range is satisfied, it is superior in branching efficiency and more effective in securing a flexible chain structure and lowering the glass transition temperature.

In the present invention, the branching agent may be represented by the following general formula (1).

[Chemical Formula 1]

(Wherein a, b, and c are integers of 1 to 14).

The branching agent may preferably have a number average molecular weight of 100 to 2,000, more preferably 150 to 1,800. When the above range is satisfied, it is effective in the branching reaction and effective in terms of introducing a uniform branch to the prepared prepolymer, but this is only a non-limiting example and is not limited to the above numerical range.

The branching agent has three reactive groups capable of reacting with an isocyanate group, and the prepolymer produced by the reaction can be used as a branch. The branched polymer includes a repeating unit having an ethylene oxide group in the molecule, and a urethane polymer a structure including a flexible chain group can be easily derived and the glass transition temperature can be relatively lowered as compared with a polyurethane having a high molecular weight without deteriorating the physical properties of the polyurethane.

Specifically, the branching agent may be trimethylolpropane ethoxylate, but is not limited thereto.

The branching agent has a flexible chain group including an ethylene oxide group so that the urethane oligomer has a flexible structure and at the same time has a property favorable for end capping by reaction with a mono-reactive material including a terminal hydroxyl group.

The branching agent may be used in an amount of 0.01 to 1 mole, preferably 0.05 to 0.8 mole, per mol of the diisocyanate, for example, the content of the prepolymer polymerization unit. The content of the branching agent is the content at which some terminals of the urethane oligomer have an isocyanate group, and remaining isocyanate groups are capped by the capping agent.

The branched prepolymer is prepared by introducing a capping agent having at least one reactive group selected from the group consisting of an yl group and a vinyl group into a terminal isocyanate group and capping the end by reaction with the capping agent to prepare an end capped polyurethane oligomer . The capping step may be performed in combination with the step of introducing a branching agent as a preliminary step and branching to form a flexible chain group in the molecular structure of the urethane oligomer and realize the inherent property of the polyurethane while remarkably lowering the glass transition temperature It is more effective.

The capping agent capping the isocyanate end of the branched prepolymer may be used without limitation as long as the terminal group or the side chain group has one reactor capable of reacting with an isocyanate such as a hydroxyl group, a thiol group or an amine group. Preferably, a reactive capping agent having an allyl group or a vinyl group with one reactor capable of reacting with isocyanate may be used. In this case, the mechanical properties of the urethane oligomer can be improved, which is effective. Specifically, any one or more mono-reactive alcohols selected from the group consisting of diallyl ether, 2-allylphenol and allyloxy bisphenol A may be used, but not always limited thereto. And more preferably, diallyl ether. Specific examples include trimethylolpropane diallyl ether, pentaerythritol triallyl ether, glycerine diallyl ether, pentaerythritol diallyl ether, and sorbitol diallyl ether But is not limited thereto. Preferably, the use of trimethylolpropane diallyl ether is more effective in terms of mono-reactive induction.

When the urethane oligomer is capped with the reactive capping agent, it has a property of further improving mechanical strength such as brittleness and impact strength when it is mixed with an epoxy or the like. In addition, when applied to an adhesive mixture such as an epoxy adhesive, curing is continuously performed even after curing, so that the impact and compressive adhesive force are increased.

The urethane oligomer endcapped in the present invention is not particularly limited, but may have a glass transition temperature of -40 캜 to 80 캜, preferably 50 캜 to -70 캜. The number average molecular weight may be 5,000 to 70,000, preferably 8,000 to 50,000, and the polydispersity index may be 1.5 to 12, preferably 2.5 to 5.0. The urethane oligomer may have a viscosity of 100,000 to 1,000,000 cP, preferably 200,000 to 500,000 cP. At this time, the viscosity was measured using a Brookfield viscometer HB type (spindle # 51) at 25 ° C.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

The physical properties of urethane oligomers prepared through the following examples and comparative examples were measured as follows.

(Glass transition temperature)

The glass transition temperature was measured using a differential scanning calorimetry (DSC) machine model TA DSC Q-2000. The measurement conditions were set in the range of 80 to 50 占 폚 at a temperature raising rate of 10 占 폚 / min in the range of 5 to 15 mg mass in a nitrogen atmosphere.

(Average molecular weight)

The average molecular weight was measured by Gel Permeation Chromatography (GPC) instrument model 1260 infinity (aqilent Tech). The columns used were PLgel 5 μm MIXED-D 300 × 7.5 mm 2, PLgel 5 μm 50 × 7.5 mm, and tetrahydrofuran (THF) as solvent.

(Compression shear adhesive strength)

The compressive shear bond strength of the epoxy adhesive was measured in accordance with KS M 3705. An aluminum plate was used as the measurement specimen, and the specifications are shown in Fig.

(Impact shear bond strength)

The impact strength of the epoxy adhesive was measured by attaching the specimen as shown in FIG. 2 through an Izod experiment according to KS M 3729. Aluminum (Al5052) was used as the measurement specimen.

(Example 1)

80 g (0.04 mol) of polypropylene glycol (PPG 2000) having a number average molecular weight of 2,000 was placed in a four-necked flask, and the mixture was degassed under reduced pressure until no more bubbles were formed at 100 캜 and then cooled to 60 캜. Subsequently, 16 g (0.072 mol) of isophorone diisocyanate (IPDI) was added and mixed with polypropylene glycol. Then, 0.2 g of a tin catalyst (di-n-butylbis (dodecylthio) tin) was added and reacted for 60 minutes. Next, 0.64 g (0.0037 mol) of trimethylolpropane ethoxylate (Mn ~ 170, Sigma-Aldrich) was added to the reaction mixture, and trimethylolpropane diallyl ether 18.0 g (0.1307 mol), and the mixture was heated to 100 DEG C and reacted for 60 minutes to obtain a liquid urethane oligomer. The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Example 2)

Except that 1.67 g of trimethylolpropane ethoxylate (TMPE-2, Mn ~ 450, Sigma-Aldrich) was used in place of TMPE-1 used in Example 1 . The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Example 3)

Except that 2.70 g of trimethylolpropane ethoxylate (TMPE-3, Mn ~ 730, Sigma-Aldrich) was used instead of TMPE-1 used in Example 1 . The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Example 4)

Except that 3.75 g of trimethylolpropane ethoxylate (TMPE-4, Mn ~ 1014, Sigma-Aldrich) was used in place of TMPE-1 used in Example 1 . The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Example 5)

Except that 2-allyl phenol (2-AP, 2-allyl phenol) was used in place of trimethylolpropane diallyl ether used in Example 2, the polymerization was carried out in the same manner as in Example 2 Respectively. The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Comparative Example 1)

80 g (0.04 mol) of polypropylene glycol (PPG 2000) having a number average molecular weight of 2,000 was placed in a four-necked flask, and the mixture was degassed under reduced pressure until no more bubbles were formed at 100 캜 and then cooled to 60 캜. Subsequently, 16 g (0.072 mol) of isophorone diisocyanate (IPDI) was added and mixed with polypropylene glycol. Then, 0.2 g of a tin catalyst (di-n-butylbis (dodecylthio) tin) was added and reacted for 60 minutes. Then, 0.5 g (0.0037 mol) of 1,1,1-trimethylolpropane was added to the reaction mixture, followed by addition of 2-allyphenol, and then 100 Lt; 0 > C and reacted for 60 minutes to obtain a liquid urethane oligomer. The number average molecular weight, weight average molecular weight, polydispersity index and glass transition temperature of the urethane oligomer thus prepared were measured and reported in Table 1 below.

(Comparative Example 2)

80 g (0.04 mol) of polypropylene glycol (PPG 2000) having a number average molecular weight of 2,000 and 16.0 g (0.07 mol) of bisphenol A were placed in a four-necked flask, and after the bisphenol A was completely dissolved at 100 DEG C, Deg.] C, and then cooled to 60 [deg.] C. Subsequently, 16 g (0.072 mol) of isophorone diisocyanate (IPDI) and 0.5 g (0.0037 mol) of 1,1,1-trimethylolpropane were added and mixed at the same time, 0.2 g of a catalyst (di-n-butylbis (dodecyl thio) tin) was added and reacted for 100 minutes to obtain a liquid urethane oligomer. The number-average molecular weight, the weight-average molecular weight, the polydispersity index and the glass transition temperature of the prepared polyurethane were measured and described in Table 1 below.

characteristic Example Comparative Example One 2 3 4 5 One 2 Branching agent TMPE-1 TMPE-2 TMPE-3 TMPE-4 TMPE-2 TMP TMP IPDI / PPG
Mole ratio 1.8 1.8 1.8 1.8 1.8 1.8 1.8 capping agent TMP diallyl ether TMP
diallyl ether TMP
diallyl ether TMP
diallyl ether 2-AP 2-AP Bisphenol A Mn 9,240 8,740 8,080 7,150 7,630 7,500 4,900 PDI 2.87 2.25 1.96 1.73 1.56 1.32 1.83 Tg (占 폚) -61.6 -61.0 -60.7 -60.4 -55.7 -49.2 -38.0

As can be seen in Table 1 above, it can be seen that the embodiments according to the present invention have low glass transition temperatures as low as -61.6 ° C. On the other hand, the comparative examples are incapable of securing a flexible chain group in the molecule by introducing the branching agent into the branching using 1,1,1-trimethylol propane (TMP) not containing ethylene oxide, The glass transition temperature was relatively high. The urethane oligomer having such a low glass transition temperature has an advantage that it can be applied to a field requiring low temperature impact resistance because it can maintain the property of an elastic body even at a low temperature. Particularly, in the case of an epoxy structural adhesive, since the brittleness of the epoxy is strong, excellent effects can be realized with a rubber-like hardening agent to compensate for such properties.

(Examples 8 and 9 and Comparative Examples 3 to 5)

The urethane oligomers of Example 1 and Comparative Example 1 were added to a modified epoxy resin composition (Bisphenol A epoxy resin: Amicure CG-1200, Air Products = 12.6: 1 by weight) having relatively low brittleness 2, and the impact strength and compressive shear bond strength were measured. The results are shown in Table 2. As a result, Examples 8 and 9 using the urethane oligomer of Example 1 according to the present invention exhibited remarkably improved compressive and impact shear bond strengths as compared with Comparative Example 4. That is, as shown in the following Table 2, the characteristics of the urethane oligomer prepared in Example 1 and Comparative Example 1 are greatly different from each other and it is confirmed that the structural characteristics attributed to the manufacturing method act.

division Polyurethane CS RP modified
Epoxy resin (wt%) Total Shear bond strength Kinds Content (wt%) Compression (MPa) Impact (kgcm) Example 8 Example 1 0.2 99.8 100 18.25 167.2 Example 9 Example 1 4.9 95.1 100 25.40 230.4 Comparative Example 3 - 0.0 100.0 100 10.98 133.5 Comparative Example 4 Comparative Example 1 4.9 95.1 100 11.36 150.1 Comparative Example 5 Commercial Products (D *) 4.9 95.1 100 5.83 177.5

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the scope of the present invention should not be construed as limiting the scope of the present invention defined by the limitations of the following claims.

Claims (10)

Reacting a diisocyanate and a diol to prepare a prepolymer having a linear structure having an isocyanate group at both terminal ends,
Introducing a branching agent represented by the following formula (1) into the prepolymer and containing an ethylene oxide group and a hydroxyl group in the molecule and branching the same; and
Reacting the capping agent with a branched prepolymer to prepare an endcapped polyurethane oligomer
≪ / RTI >
[Chemical Formula 1]

(Wherein, a, b and c are integers of 1 to 20). The method according to claim 1,
Wherein the branching agent is a urethane oligomer having an ethylene oxide group and a hydroxyl group ratio (EO / OH) of 0.26 to 14 and a number average molecular weight of 150 to 2,000. delete The method according to claim 1,
Wherein the capping agent is a diallyl ether having one functional group that reacts with isocyanate. The method according to claim 1,
Wherein the diisocyanate is at least one selected from the group consisting of isophorone diisocyanate, 1,6-hexamethylene diisocyanate, toluene diisocyanate and 4,4'-methylene diphenyl isocyanate. The method according to claim 1,
Wherein the diol has a number average molecular weight of 100 to 6,000 and is at least one selected from aliphatic ether diols and ester diols. The method according to claim 1,
Wherein the prepolymer has a number average molecular weight of 4,000 to 20,000. The method according to claim 1,
Wherein the diisocyanate has a molar ratio to the diol of 1.5 to 2.0. A urethane oligomer produced by a process according to any one of claims 1 to 2 and 4 to 8. 10. The method of claim 9,
The urethane oligomer is a urethane oligomer having a number average molecular weight of 5,000 to 70,000, a polydispersity index of 1.5 to 12, and a viscosity (40 ° C, Brookfield viscometer) of 100,000 to 1,000,000 cP.

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