KR20080051602A - Composition for plasticizer-free thermoplastic polyurethane elastomer and polyurethane elastomer having low hardness manufactured therefrom - Google Patents

Abstract

A composition for a plasticizer-free thermoplastic polyurethane resin is provided to realize excellent reactivity and processability, and to obtain a polyurethane resin having a low Shore hardness of 80 or less. A composition for a plasticizer-free thermoplastic polyurethane resin comprises: 62-76 wt% of at least two polyols having different molecular weights; 20-30 wt% of a diisocyanate; and 4-8 wt% of a chain extender. The two polyols have a number average molecular weight of 1,000-4,000, and the mixed polyol containing at least two polyols having different molecular weights has a number average molecular weight of 1,100-3,900. The polyol includes an ethyleneoxide-capped polyol.

Description

Composition for preparing thermoplastic polyurethane resin that does not contain plasticizer and low hardness polyurethane resin produced therefrom

[TECHNICAL FIELD OF THE INVENTION]

The present invention relates to a composition for preparing a thermoplastic polyurethane resin that does not contain a plasticizer, and a low hardness polyurethane resin prepared therefrom. More particularly, the present invention is excellent in reactivity and processability without containing a plasticizer, and has a resistance of 80 A (shore) or less. It relates to a polyurethane resin composition having a low hardness and a low hardness polyurethane resin prepared therefrom.

[Private Technology]

Thermoplastic polyurethane resin is a polymer having elasticity, such as rubber at room temperature, but easily plasticized at high temperature and capable of molding such as injection and extrusion, and has a low strength than general plastics, but has advantages of being transparent and excellent in wear resistance. In addition, thermoplastic polyurethane has a lower elasticity than rubber, but has excellent mechanical properties and wear resistance, and thus is used as a substitute for conventional rubber.

However, thermoplastic polyurethane resins have a lot of restrictions in manufacturing products having a hardness of 80 A or less due to problems such as reactivity and processability (injection moldability).

In order to solve the above problem, the prior art has introduced a plasticizer. However, the plasticizer has a problem that (bleed-out) to the surface of the resin over time, thereby reducing the adhesive strength of the resin, the physical properties such as hardness. In addition, phthalate-based plasticizers, which are the most common plasticizers, are restricted and used as toxic substances.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a plasticizer-free thermoplastic polyurethane resin composition having excellent reactivity and processability and a low hardness of 80 A (shore) or less without containing a plasticizer. It is done.

Another object of the present invention is to provide a low hardness polyurethane resin prepared from the composition and having low Shore hardness.

Another object of the present invention is to provide a method for producing the polyurethane resin.

In order to achieve the above object, the present invention is 62 to 76% by weight of two or more polyols having different molecular weights; 20 to 30 weight percent diisocyanate; And it provides a composition for producing a thermoplastic polyurethane resin of a plasticizer comprising a chain extender (4 to 8% by weight).

According to the present invention, the polyol preferably has a number average molecular weight of 1,000 to 4,000, and a polyol having two or more kinds of different molecular weights mixed with each other preferably has a number average molecular weight of 1,100 to 3,900.

The present invention also provides a low hardness thermoplastic polyurethane resin prepared from the composition and having a Shore hardness of 60 A to 70 A measured by the ASTM D2240 method.

In addition, the present invention comprises the steps of a) 62 to 76% by weight of two or more polyols having different molecular weights, 20 to 30% by weight diisocyanate, and 4 to 8% by weight chain extender (chain extender); b) mixing the reactants with a mixing means and polymerizing at a reaction temperature of 180 to 220 ° C; And c) provides a method for producing a plasticizer-free low hardness thermoplastic polyurethane resin comprising the step of drying the polymerized resin.

Hereinafter, the present invention will be described in more detail.

In the course of studying the thermoplastic polyurethane resin, the present inventors have a low hardness of 80 A (shore) or less when mixing two or more polyols having different molecular weights into the composition without containing a plasticizer, thereby forming injection molding. Not only this, but also developed a plasticizer-free polyurethane resin composition for excellent mechanical properties and transparency, to complete the present invention based on this.

The plasticizer-free thermoplastic polyurethane resin composition according to the present invention contains 62 to 76% by weight of two or more polyols having different molecular weights, 20 to 30% by weight of diisocyanate, and 4 to 8% by weight of a chain extender. It is characterized by including.

In the present invention, the polyol is preferably used by mixing two or more kinds having different molecular weights.

That is, in the related art, in order to control the hardness of the polyurethane resin composition, a method of adjusting the -NCO / -OH ratio in the composition was used, but the method had limitations in satisfying injection molding and transparency of the composition at the same time. Thus, the present invention is to adjust the number average molecular weight to an appropriate range by mixing two or more polyols having different molecular weight, accordingly has excellent injection molding and excellent transparency.

Preferably, the polyol has a number average molecular weight of 1,000 to 4,000. In addition, the mixed polyol in which two or more kinds of polyols having different molecular weights are mixed preferably has a number average molecular weight of 1,100 to 3,900, and more preferably 1,500 to 3,000. That is, the number average molecular weight of the mixed polyol is preferably 1,100 or more, and the number average molecular weight is 3,900 or less in order to prevent the transparency from decreasing in order to prevent the cooling solidification rate from being lowered and the moldability decreases. .

In addition, the polyol is preferably ethylene oxide-capped, more preferably ethylene oxide-sealed polypropylene glycol.

In this case, the polyol is preferably 15 to 50 mol% of the content of ethylene oxide relative to the entire polyol. That is, the content of ethylene oxide is preferably 15 mol% or more for the production of low hardness thermoplastic elastomer, and the content of ethylene oxide is preferably 50 mol% or less in order to exhibit sufficient tensile strength and elongation.

In addition, the polyol is preferably included in 62 to 76% by weight based on the total composition. That is, the content of the polyol is preferably 62% by weight or more in order to prevent the hardness from increasing to 80 A or more, and the content of the polyol is 76% by weight in order to prevent the reactivity and the degree of polymerization from increasing, thereby preventing the expression of desirable physical properties. It is preferable that it is the following.

In the present invention, the diisocyanate may be at least one selected from the group consisting of aromatic diisocyanate, aliphatic diisocyanate and cyclized aliphatic diisocyanate.

As said aromatic diisocyanate, 1, 4- phenylene diisocyanate, 2, 4- toluene diisocyanate, 2, 6- toluene diisocyanate, 2, 2- methylene diphenylene diisocyanate, 2, 4'- methylene diphenylenedi isocyanate And at least one selected from the group consisting of 4,4'-methylenediphenylenediisocyanate and naphthalene diisocyanate. In addition, the aliphatic diisocyanate or cycloaliphatic diisocyanate is preferably cyclohexane diisocyanate, hexamethylene diisocyanate or isophorone diisocyanate.

The content of the diisocyanate is preferably included in 20 to 30% by weight. That is, the content of the diisocyanate is preferably 20% by weight or more, and preferably 30% by weight or less in order to prevent the hardness from becoming higher than necessary in order to prevent the polymerization degree from decreasing due to low reactivity and to express the minimum mechanical properties. Do.

In the present invention, the chain extender (chain extender) is a compound containing a diol group, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2-methyl Preference is given to at least one member selected from the group consisting of pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and neopentylglycol.

The content of the chain extender is preferably included in 4 to 8% by weight. That is, the content of the chain extender is preferably 4% by weight or more, and 8% by weight or less in order to prevent the hardness from becoming higher than necessary in order to prevent reactivity.

In addition, the polyurethane resin composition according to the present invention may be polymerized even without a separate catalyst, and may further include a catalyst as necessary to improve polymerization reactivity.

The catalyst may be a conventional catalyst used in preparing a thermoplastic polyurethane resin, and a tertiary amine compound or an organometallic compound is preferable, but is not limited thereto. The tertiary amine compounds include triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N, N'-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol and diazabicyclo (2,2 It is preferable to select at least one from the group consisting of 2, -octane. The organometallic compound is preferably at least one selected from the group consisting of tin diacetate, tin dioctoate, tin dilaurate and dibutyl tin dilaurate.

The catalyst may be determined according to the process conditions such as the content of the polyurethane resin composition, the temperature of the reactor, the residence time, and the like, and may be used in 0.001 to 0.1% by weight.

On the other hand, the present invention provides a low hardness thermoplastic polyurethane resin prepared from such a composition.

Polyurethane resin according to the present invention has the advantage of low moldability as it is prepared from the composition as described above. That is, the polyurethane resin preferably has a Shore hardness of 70 A or less, more preferably 60 A to 80 A, as measured by the ASTM D2240 method.

The method for preparing the polyurethane resin includes a) adding 62 to 76 wt% of two or more polyols having different molecular weights, 20 to 30 wt% of diisocyanate, and 4 to 8 wt% of a chain extender in a reactor. step; b) mixing the reactants with a mixing means and polymerizing at a reaction temperature of 180 to 220 ° C; And c) drying the polymerized resin.

In this case, in the polymerization step, a batch reactor or a continuous reaction extruder may be used. The batch reactor is a method of adding the polyurethane resin composition to a reactor, reacting at a predetermined level, then discharging and further heat treatment. The method of using the continuous reaction extruder is an extruder through a metering unit from a raw material storage tank. It is a method of completing the reaction in an extruder by supplying a composition for producing a polyurethane resin.

Among the above production methods, it is more preferable to use a continuous reaction extruder having excellent quality uniformity. When using the continuous reaction extruder, it is preferable that the dough block is 10 to 40% of the total screw in order to prevent the resin properties from deteriorating. In addition, in consideration of the transparency and mechanical properties of the resin, the polymerization temperature is preferably 180 to 220 ℃.

In addition, the mixing means in the polymerization step is preferably a screw. In particular, when using a continuous reaction extruder, the rotation speed of the screw is preferably 170 to 330 rpm in order to prevent the physical properties and color quality of the resin from deteriorating.

The polyurethane resin polymerized as described above may be manufactured in the form of chips using a pelletizer, and dried at 50 to 90 ° C. for 3 to 6 hours using a dehumidifying dryer to obtain a low hardness thermoplastic polyurethane resin. have.

Hereinafter, preferred examples will be described to aid in understanding the present invention. However, the following examples are merely described for the purpose of more clearly expressing the present invention, and the contents of the present invention are not limited to the following examples.

Example  One

As the polyol, a blended polypropylene glycol having a mixture of two different molecular weights was used. That is, the blend polypropylene glycol is 1) polypropylene glycol having an ethylene oxide content of 21.9 mol% and a number average molecular weight of 1,000 (product name: Poly G55-112, manufacturer: Arch chem); And 2) polypropylene glycol having an ethylene oxide content of 21.9 mol% and a number average molecular weight of 3,000 (product name: Poly G55-37, manufacturer: Arch chem) by mixing the number average molecular weight to 1,860 to 73.84% by weight of the total composition Was added.

In addition, 21.86% by weight of 4,4'-methylenediphenyl-diisocyanate was added as diisocyanate and 4.30% by weight of 1,4-butanediol as a chain extender.

The components were then fed into a continuous reaction extruder (Model: Werner & Pfleiderer ZSK 58 twin screw extruder). The continuous reaction extruder was kneaded block 30% of the total screw, the polymerization was carried out under the conditions of the screw rotation speed 250 rpm and the reaction temperature of 190 to 220 ℃.

The resin polymerized in the continuous reaction extruder was manufactured in the form of chips using a pelletizer, and dried at 70 ° C. for 5 hours using a dehumidifying dryer (Conair SC60, Inlet air dew point = -50 ° C.) to not contain a plasticizer. Thermoplastic polyurethane resin was obtained.

Example  2 to 4

As shown in Table 1, a polyurethane resin was prepared in the same manner as in Example 1 except for changing the content of the components included in the composition.

Comparative example  1 to 3

As shown in Table 1 below, a polyurethane resin was prepared in the same manner as in Example 1, except that one polyol having a single molecular weight was used.

At this time, the polyol used in Comparative Example 1 is a polypropylene glycol having a ethylene oxide content of 21.9 mol% and a number average molecular weight of 1,000 (product name: Poly G55-112, manufacturer: Arch chem) alone, and a polyol used in Comparative Example 2. Silver polyethylene glycol (product name: Poly G55-37, manufacturer: Arch chem) having an ethylene oxide content of 21.9 mol% and a number average molecular weight of 3,000 alone, the polyol used in Comparative Example 3 has an ethylene oxide content of 21.9 mol% Polypropylene glycol having a number average molecular weight of 2,000 (product name: Poly G55-56, manufactured by Arch chem) alone.

Experimental Example

The physical properties of the resins of Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2.

1) Hardness: After the injection and molding of polyurethane resin, the hardness was measured based on ASTM D2240 method.

2) Injection moldability: The moldability of the resin was evaluated using an injection machine. The injection machine was manufactured by Engel, Germany (Model: ES240 / 75P), and used a clamping force of 75 tons, a screw diameter of 35 mm, and a screw stroke of up to 160 mm. The dimensions of the cavity used for molding were 125 × 125 × 2 mm. In this case, the cycle time during injection molding (cycle time) was measured, the shorter the cycle time means that the injection molding is excellent.

3) Mechanical Properties: Tensile strength and elongation were measured based on ASTM D412, and tear strength was measured based on ASTM D624.

4) UV Stability: UV exposure test was performed for 24 hours based on ASTM G53.

5) Melt Flow Index: The flowability of the resin was evaluated based on ASTM D1238. At this time, measurement conditions were made into the temperature of 190 degreeC, and load 5000g.

6) Transparency: The transparency of the specimen was measured based on ASTM D1033.

From the results of Table 2, Examples 1 to 5 include two or more kinds of polypropylene glycols having different molecular weights, and thus have excellent injection moldability compared to Comparative Example 1 using polypropylene glycol having a molecular weight of 1000 alone. It can be seen that the transparency is superior to Comparative Example 2 using a polyol having a molecular weight of 3000 alone. In addition, it can be seen that Examples 1 to 5 are superior in injection moldability and transparency as compared with Comparative Example 3 using polypropylene glycol having a molecular weight of 2000 alone.

As described above, the thermoplastic polyurethane resin composition according to the present invention does not contain a plasticizer and has excellent reactivity, but the polyurethane resin prepared therefrom does not cause plasticizer shedding, and particularly has a low hardness of 70 A or less. In addition to having excellent moldability, there is an advantage in excellent mechanical properties and transparency.

Claims (11)

62 to 76% by weight of two or more polyols having different molecular weights; 20 to 30 weight percent diisocyanate; And Chain extender 4 to 8% by weight Plasticizer-free thermoplastic polyurethane resin composition comprising a. The method of claim 1, The polyol has a number average molecular weight of 1,000 to 4,000, The polyol mixed with two or more kinds of different molecular weight has a number average molecular weight of 1,100 to 3,900, the composition for producing a thermoplastic polyurethane resin. The method of claim 1, The polyol is a composition for producing a thermoplastic polyurethane resin is ethylene oxide-capped. The method of claim 3, The polyol is a composition for producing a thermoplastic polyurethane resin is ethylene oxide sealed polypropylene glycol. The method of claim 3, The polyol is a composition for producing a thermoplastic polyurethane resin is 15 to 50 mol% ethylene oxide content. The method of claim 1, The diisocyanate is at least one selected from the group consisting of aromatic diisocyanate, aliphatic diisocyanate and cycloaliphatic diisocyanate composition for producing a thermoplastic polyurethane resin. The method of claim 1, The chain extender is ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2-methylpentanediol, 1,5-pentanediol, 1,6-hexanediol , 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and neopentylglycol is selected from the group consisting of at least one thermoplastic polyurethane resin composition. A low hardness thermoplastic polyurethane resin prepared from the composition according to claim 1. The method of claim 8, The polyurethane resin is a low hardness thermoplastic polyurethane resin that is measured by ASTM D2240 method Shore hardness is 60A to 80A. a) 62 to 76% by weight of two or more polyols having different molecular weights, 20 to 30% by weight of diisocyanate, and 4 to 8% by weight of a chain extender; b) mixing the reactants with a mixing means and polymerizing at a reaction temperature of 180 to 220 ° C; And c) drying the polymerized resin Method for producing a low hardness thermoplastic polyurethane resin of a plasticizer comprising a. The method of claim 10, Wherein the reactor is a batch type or continuous reaction extruder.