KR101407251B1 - Halogen-free flame retardant thermoplastic polyurethanes - Google Patents

Abstract

The present invention relates to a non-halogen flame retardant thermoplastic polyurethane composite resin composition, and more particularly, to a thermosetting polyurethane resin composition comprising an organic isocyanate-containing thermoplastic polyurethane resin and an organic phosphate compound and a melamine or melamine derivative as flame retardants. Flame retardant thermoplastic polyurethane resin composition which does not contain a halogen-based flame retardant, which is excellent in mechanical properties while at the same time solving the problems of flame retardancy and dripping of a thermoplastic polyurethane resin.

Thermoplastic polyurethane, active isocyanate, organic phosphate flame retardant, melamine, melamine derivative, self-extinguishing,

Description

[0001] Halogen-free flame retardant thermoplastic polyurethanes [0002]

The present invention relates to a non-halogen flame retardant thermoplastic polyurethane composite resin composition, and more particularly, to a thermosetting polyurethane resin composition comprising an organic isocyanate-containing thermoplastic polyurethane resin and an organic phosphate compound and a melamine or melamine derivative as flame retardants. Flame retardant thermoplastic polyurethane resin composition which does not contain a halogen-based flame retardant, which is excellent in mechanical properties while at the same time solving the problems of flame retardancy and dripping of a thermoplastic polyurethane resin.

The thermoplastic polyurethane resin generally has excellent mechanical properties such as excellent abrasion resistance and excellent elasticity, and is a thermoplastic resin which can produce a product through processes such as injection, extrusion and the like unlike a thermosetting resin such as a crosslinked rubber which is a general elastic body It is used in various industrial fields such as automobile, electric wire, pneumatic hose, and shoes. However, due to the fragile flame retardant properties of thermoplastic polyurethane resins, their use has been limited in some areas where very good flame retardancy is required. Accordingly, methods for imparting flame retardancy to such a thermoplastic polyurethane resin have been developed, and methods of adding a flame retardant to the thermoplastic polyurethane resin have been mainly used. However, when a flame retardant is added for the flame retardancy of the thermoplastic polyurethane resin, mechanical properties such as tensile strength, rebound resilience, elastic modulus, and abrasion deteriorate. Therefore, it is preferable to add a minimum amount of flame retardant to the resin in order to minimize this. In addition, the thermoplastic polyurethane resin is decomposed upon combustion and becomes a low-molecular-weight molten material, thereby causing a flaming drip to be dripped. Such a dripping phenomenon can further spread the fire when a fire occurs. Therefore, it is one of very important matters to be considered in the development of the flame retardant thermoplastic polyurethane resin to improve the dripping phenomenon in the combustion.

One of the methods for improving the flame retardancy of a thermoplastic polyurethane resin is a method in which a halogen-based flame retardant is used alone or in combination with a halogen-based flame retardant and a metal oxide compound such as antimony oxide. However, the resin using such a halogen-based flame retardant has a problem that it is difficult to apply it to some applications due to the toxicity and corrosiveness of the smoke generated in the combustion. Therefore, in recent years, research and development have been conducted on a flame retardant thermoplastic polyurethane resin using a non-halogen flame retardant to solve the problem of using such a halogen flame retardant.

For example, U.S. Patent No. 4,413,101 discloses that when the high molecular weight resin composed of polyarylphosphonate and polyarylphosphonate carbonate is used in an amount of 20 to 40 parts by weight of the flame retardant, the oxygen index of the thermoplastic polyurethane resin increases The flame retardancy is increased, but there is no mention about the physical property or the flame-dripping phenomenon.

U.S. Patent No. 4,542,170 discloses the use of phosphorus-containing salts of amino-s-triazine and nitrogen-containing phosphates such as amine phosphate, ammonium phosphate, and ammonium polyphosphate as flame retardants to improve the flame retardancy of thermoplastic polyurethane resins, However, it can be confirmed that the mechanical properties such as the tensile strength are significantly lowered.

In addition, U.S. Patent No. 5,110,850 discloses that the flame retardancy of a flame-retardant thermoplastic polyurethane resin made by using melamine alone as a flame retardant improves flame retardancy to UL94 V0 level, but there is no description about flame-retardant phenomenon.

In addition, U.S. Patent No. 5,837,760 discloses a flame retardant thermoplastic polyurethane resin composition using melamine cyanurate and an organic phosphate or organic phosphonate blend, but no mention is made of mechanical properties.

Accordingly, there is a need to prepare a flame retardant thermoplastic polyurethane resin having improved flame retardancy of the thermoplastic polyurethane resin without deteriorating mechanical properties and improving the phenomenon of spill dropping

As a result, the present inventors have found that a thermoplastic polyurethane resin having an active isocyanate group can be combined with an organic phosphate compound and a melamine or a melamine derivative as a flame retardant, Halogen flame retardant thermoplastic polyurethane composite resin composition which is excellent in digestibility, hardly spoils, and also has excellent mechanical properties, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a thermoplastic polyurethane resin composition which comprises 50 to 80% by weight of a thermoplastic polyurethane resin having an active isocyanate group, 1 to 20% by weight of an organic phosphate compound as a flame retardant and 5 to 40% by weight of a melamine or melamine derivative, And is excellent in mechanical properties such as tensile strength as well as improvement in flame retarding phenomenon at the time of combustion, and to provide a flame retardant thermoplastic polyurethane resin composition.

The present invention relates to a halogen-free flame-retardant thermoplastic polyurethane resin composition comprising 50 to 80% by weight of a thermoplastic polyurethane resin having an active isocyanate, 1 to 20% by weight of an organic phosphate compound as a flame retardant, and 5 to 40% by weight of a melamine or melamine derivative ≪ / RTI >

Hereinafter, the present invention will be described in detail.

The present invention relates to a thermoplastic polyurethane resin having an active isocyanate and an organophosphate compound and a melamine or a melamine derivative as a flame retardant, And at the same time, the flame retardant thermoplastic polyurethane resin composition is excellent in mechanical properties and does not contain a halogen-based flame retardant.

The thermoplastic polyurethane resin used in the present invention is composed of a hard segment and a soft segment, wherein the hard segment is derived by reacting a diol as a diisocyanate and a chain extender, and the soft segment is induced by reacting a polyol with a diisocyanate . The properties of the soft segments are determined by the type of polyol used.

The diisocyanate may be an aromatic diisocyanate, an aliphatic diisocyanate, and a cyclized aliphatic diisocyanate, either singly or in combination. Examples of the aromatic diisocyanate include 1,4-phenylenediisocyanate 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof, 2,2-methylenediphenylenediisocyanate, 2,4'-methylenediphenyl 4,4'-methylenediphenylenediisocyanate, and mixtures thereof, and naphthalene diisocyanate, and the like. The aliphatic diisocyanate or the cyclic aliphatic diisocyanate includes cyclohexane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, H12 MDI and the like.

The diol used as the chain extender may be at least one selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2-methylpentanediol, -Hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol, which may be used alone or in combination.

The polyol may be broadly classified into a polyester polyol and a polyether polyol. The polyester polyol is produced by the reaction of one or more dicarboxylic acids and one or more diols. Examples of the dicarboxylic acid include adipic acid, sebacic acid, suberic acid, methyl adipic acid, glutaric acid and azelaic acid, and the diol includes ethylene glycol, 1,3- or 1,2-propylene glycol , 1,4-butanediol, 2-methylpentanediol, 1,5-pentanediol, and 1,6-hexanediol. Also, cyclic carbonates such as? -Caprolactone and the like can also be used in the production of polyester polyols. Polyester polyols mainly used are mainly poly (ethylene adipate) and poly (1,4-butylene adipate), or mixtures thereof, and poly (epsilon -caprolactone) is also mainly used.

The polyether polyol is obtained by an addition polymerization reaction of an alkylene oxide. The alkylene oxides usable in the present invention include ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran. The polyether polyols mainly used are either poly (propylene oxide) glycol and poly (tetramethylene ether) glycol, or a mixture thereof.

The molecular weight of the polyol constituting the soft segment of the thermoplastic polyurethane is preferably 500 to 8000, more preferably 800 to 5000.

Generally, the catalyst used for the thermoplastic polyurethane resin includes a tertiary amine series and an organometallic compound. As the tertiary amine series catalyst, triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N, N'-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol and diazabicyclo 2,2) -octane, and the organic metal compounds include tin diacetate, tin dioctoate, tin di-laurate, and dibutyl tin dilaurate. The catalyst mainly used is an organometallic compound alone or a mixture thereof.

As the polymerization method of the thermoplastic polyurethane resin, there can be employed a method using a batch reactor or a method using a continuous reaction extruder. The method using the batch type reactor is a method in which reactants are fed into a reactor to react to a predetermined level and then discharged and further heat-treated to complete the reaction. In the method using the continuous type reaction extruder, And the reaction is completed in the extruder. Compared with the batch type reactor, polymerization using a continuous type reaction extruder is superior in quality uniformity of products due to uniform heat transfer and the like. Recently, a method using a reaction extruder has been mainly used.

When a thermoplastic polyurethane resin is produced using a continuous reaction extruder, the temperature of the extruder is preferably 150 to 250 ° C, more preferably 170 to 210 ° C.

Generally, various methods of adding various kinds of flame retardants to a resin are known in order to impart flame retardancy to the thermoplastic polyurethane resin. The most common methods are halogen-based flame retardants such as chlorine-based or bromine- And a method in which a metal oxide compound such as monooxide is mixed is used. Although the flame retardant thermoplastic polyurethane resin using such a halogen-based flame retardant exhibits excellent flame retardancy and mechanical properties, it is difficult to apply it to some applications due to the toxicity and corrosiveness of smoke generated in the combustion. Therefore, recently, in order to solve the problem of using such a halogen flame retardant, a product using an organic phosphate or a non-halogen flame retardant such as a melamine or a melamine derivative has been developed. However, when the organic phosphate-based flame retardant is used, the mechanical properties of the thermoplastic polyurethane resin are not significantly deteriorated. However, there is a disadvantage that the flame retardancy of the UL-94 V2 level can not be obtained. In the case of the melamine- , The flame retardancy is comparatively excellent. However, the thermoplastic polyurethane resin and the thermoplastic polyurethane resin are decomposed during melt-kneading, resulting in a drastic decrease in the molecular weight of the resin, thereby greatly deteriorating mechanical properties.

When the active isocyanate is introduced into the thermoplastic polyurethane resin, the melamine-based flame retardant alone or in combination with the organic phosphate-based flame retardant reacts with the active isocyanate and the hydroxyl group which is the terminal group of the thermoplastic polyurethane resin to form an in- It is possible to solve the problem of lowering the mechanical properties due to the lowering of the molecular weight due to the decomposition described above by the present inventors. Therefore, according to the present invention, by using a thermoplastic polyurethane resin containing an active isocyanate group in an amount of 0.1 to 1% by weight in the thermoplastic polyurethane resin at the time of melt kneading with the flame retardant, the mechanical properties of the non-halogen flame retardant thermoplastic polyurethane resin can be effectively Can be improved.

The factors affecting the active isocyanate group content in the thermoplastic polyurethane resin include the equivalence ratio of the isocyanate group to the hydroxyl group present in the polyol as the reaction raw material of the thermoplastic polyurethane resin, the amount of the introduced catalyst, the reaction temperature, Time of stay at. The screw structure of the reaction extruder at the time of continuous operation, the drying temperature of the thermoplastic polyurethane resin produced, and the drying time.

The thermoplastic polyurethane resin is obtained by the reaction of hydroxyl groups and isocyanate groups present in the polyol and chain extender. If the equivalence ratio of the isocyanate groups to the hydroxyl groups is increased, the active isocyanate content in the thermoplastic polyurethane resin after production is increased. However, when the equivalent ratio of the isocyanate group to the hydroxyl group is too high or too low, a high molecular weight thermoplastic polyurethane resin can not be obtained and sufficient effect can not be obtained. Therefore, in order to obtain a thermoplastic polyurethane resin having effective mechanical properties in the melt kneading with the melamine-based flame retardant, the equivalent ratio (NCO / OH) of the isocyanate group to the hydroxyl group is preferably 1.00 to 1.10. More preferably 1.01 to 1.08, and most preferably 1.02 to 1.06.

In addition, the amount of the catalyst added in the production of the thermoplastic polyurethane resin also affects the active isocyanate group content of the thermoplastic polyurethane resin. The amount of active isocyanate group in the thermoplastic polyurethane resin is decreased due to the high reaction rate when the amount of the catalyst added is high. If the amount of the catalyst is too small, sufficient reaction can not be carried out, and a high molecular weight thermoplastic polyurethane resin I can not get it. The amount of the catalyst added varies depending on the kind of the catalyst, the composition of the thermoplastic polyurethane resin, the temperature of the reactor, and the production process conditions such as the residence time and the like, and it is generally preferable to use a catalyst of 10 to 1000 ppm.

The production process conditions of the thermoplastic polyurethane resin may also affect the active isocyanate group content in the thermoplastic polyurethane resin.

The temperature of the reactor can also influence the active isocyanate group content in the thermoplastic polyurethane resin. When the temperature of the reactor is too high, the reaction completion degree is high and the active isocyanate group content in the thermoplastic polyurethane resin is decreased. When the temperature of the reactor is too low, the reaction is not sufficiently carried out and the molecular weight is low. When a thermoplastic polyurethane resin is produced as a modifier for improving the impact resistance of a polyoxymethylene resin by using a continuous reaction extruder, the temperature of the extruder is preferably 150 to 250 占 폚, more preferably 170 to 210 占 폚.

When the thermoplastic polyurethane resin is produced using the continuous reaction extruder, the structure of the extruder screw may affect the active isocyanate group content. When the kneading block and the reverse block are present in the screw, the melt-kneading effect of the reactant is enhanced and the product quality uniformity is improved. However, since the reaction completion degree is increased due to the high frictional heat, the active isocyanate group content in the resin is decreased, When the dough block and the reverse block are small, the melt-kneading effect of the reactant is lowered and the uniformity of the quality of the product is lowered. Therefore, when a suitable thermoplastic polyurethane resin is produced as the impact resistance improving modifier of the polyoxymethylene resin, the length of the kneading block and reverse block of the extruder screw is preferably 10 to 40% of the whole.

Also, when the thermoplastic polyurethane resin is produced by using the continuous reaction extruder, the residence time of the reactants in the extruder may affect the active isocyanate group content. The residence time of the reactants in the extruder is determined by the number of revolutions (rpm) of the continuous extruder screw and the rate of introduction of the reactants. If the residence time of the reactants in the extruder is long, the active isocyanate content is reduced due to the high reaction completion.

Another major factor controlling the active isocyanate group content in the thermoplastic polyurethane resin is post-production drying conditions. In the case of the thermoplastic polyurethane resin, the moisture content is known to have a great influence on the resin properties. When the water content in the resin is high, the residual moisture in the thermoplastic polyurethane processing step reacts with the thermoplastic polyurethane resin to decompose the thermoplastic polyurethane resin, thereby lowering the molecular weight of the thermoplastic polyurethane resin during melt-kneading with the flame retardant, , The quality of the product is deteriorated due to the air bubbles generated by the moisture in the molded product during the melt kneading, and the active isocyanate content is decreased by moisture during storage of the product. Accordingly, the thermoplastic polyurethane resin preferably has a water content of not more than 1000 ppm (0 to 1000 ppm), more preferably not more than 800 ppm (0 to 800 ppm), most preferably not more than 500 ppm (0 to 500 ppm). Further, in general, it is preferable to use a dehumidifying dryer in order to effectively regulate the moisture content.

When the thermoplastic polyurethane resin is dried, the content of the active isocyanate group in the thermoplastic polyurethane resin is influenced by the temperature of the dryer and the drying time. If the drying temperature is too high or the drying time is too long, the active isocyanate content in the thermoplastic polyurethane resin is reduced. Therefore, the thermoplastic polyurethane resin used as an impact resistance improving modifier of polyoxymethylene must not only have a low water content so that the characteristics of the thermoplastic polyurethane can be effectively exhibited during melt-kneading, but also has a drying temperature and a drying time so that sufficient isocyanate groups remain after drying It should be adjusted.

The drying temperature of the thermoplastic polyurethane resin suitable for use as an effective impact modifier for improving the impact resistance of the polyoxymethylene resin is preferably 40 to 100 ° C, more preferably 50 to 90 ° C, and most preferably 60 to 80 ℃ is good. The drying time is preferably 2 to 10 hours, more preferably 3 to 9 hours, and most preferably 4 to 8 hours. The thermoplastic polyurethane resin dried through such a drying condition has a low water content in the resin and a large amount of active isocyanate group is present in the resin and can exhibit sufficient effect as a shock resistance improving modifier of the polyoxymethylene resin.

Among the factors affecting the active isocyanate content in the thermoplastic polyurethane resin as described above, the factors that have the greatest influence are the equivalence ratio of the isocyanate groups to the hydroxyl groups of the reactants and the drying conditions

In the present invention, the thermoplastic polyurethane resin having an active isocyanate group is preferably used in an amount of 50 to 80% by weight, more preferably 60 to 75% by weight. When the content is less than 50% by weight, the mechanical properties of the flame retardant thermoplastic resin composition are deteriorated. When the content is more than 80% by weight, a sufficient flame retardant thermoplastic resin composition fails to exhibit flame retardancy.

In general, phosphate-based flame retardants are known to be highly effective for resins having high oxygen content in the resin, such as cellulose and thermoplastic polyurethane resins, in particular, by imparting flame retardancy to resins by inhibiting decomposition in the condensation phase and increasing the degree of carbonization have. These phosphate-based flame retardants produce metaphosphoric acid, polymetaphosphoric acid and the like by pyrolysis during combustion, and are very excellent in blocking effect by char formation due to the formation of a protective layer by a phosphate layer and dehydration by polymetaphosphoric acid It is used as a flame retardant for many resins. In the present invention, an organic phosphate-based flame retardant is selected which can obtain excellent flame retardancy even when a relatively small amount of such phosphate-based flame retardant is used and can minimize the degradation of the mechanical properties of the resin due to the addition of a small amount of flame retardant. The organic phosphate-based flame retardant is preferably a phosphoric acid ester compound free of halogen elements such as trialkyl phosphate, particularly triaryl phosphate. Triaryl phosphate based flame retardants are also known as flame retardant plasticizers in the plastics industry, as they are also effective as plasticizers. Examples of such organic phosphate-based flame retardants include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, cres di di 2,6-xylyenyl phosphate, isodecyl diphenyl phosphate, P-tert-butylphenyl diphenyl phosphate, di-p-tert-butylphenyl diphenyl phosphate, resorcinol diphenyl phosphate, and oligomer type polyphosphate. Particularly, a liquid phase organic phosphate-based flame retardant such as cresyl diphenyl phosphate can be produced by adding from a thermoplastic polyurethane (TPU) polymerization stage, thereby making a flame retardant thermoplastic polyurethane resin excellent in dispersibility relative to other phosphate stabilizers have.

However, when such an organic phosphate-based flame retardant is used alone as a flame retardant of a thermoplastic polyurethane resin, flame retardancy can be obtained to a certain extent, but there is a problem of dripping when the flame is dropped during combustion. Therefore, There is a limit in obtaining a thermoplastic polyurethane composition.

In the present invention, a melamine-based flame retardant such as melamine or a melamine derivative is mixed with an organic-based flame retardant in order to improve the dripping phenomenon in which the flame is dropped during combustion. The melamine-based flame retardant is less toxic than the halogen-based flame retardant and is easy to handle, and is known as a flame retardant agent that does not cause toxic gases during pyrolysis and does not affect human health and the environment. Examples of such melamine-based flame retardants include melamine, melamine cyanurate, melamine phosphate, melamine polyphosphate, and melamine borate. However, when such a melamine-based flame retardant is used alone as a flame retardant of a thermoplastic polyurethane resin, flame retardancy can be obtained to a certain extent, as in the case of a phosphate-based flame retardant, but when the melamine-based flame retardant is used alone as a flame retardant for a thermoplastic polyurethane resin, There is a problem in that the resin is not sufficiently flame retarded and the mechanical properties are deteriorated by lowering the molecular weight of the resin during the melt-kneading with the thermoplastic polyurethane resin.

As described above, when the organic phosphate-based compound and the melamine-based flame retardant are used alone as the flame retardant of the thermoplastic polyurethane resin, it is not easy to obtain a flame retardant thermoplastic polyurethane resin composition having sufficient self-extinguishing properties and free from dropping phenomenon . However, when these two kinds of flame retardants are mixed, an expansion tear char layer is formed due to the synergistic action between the two types of flame retardants, thereby suppressing divergence of oxygen and heat. Thus, the flame retardancy is increased and flame dropping phenomenon is improved and the thermoplastic polyurethane resin The flame retardancy can be greatly improved

Particularly, it was possible to solve such a problem of dripping by the synergistic effect of the flame retardant effect produced by mixing the phosphate flame retardant and the melamine flame retardant used in the present invention. When the phosphorus flame retardant is used in combination with a nitrogen compound, phosphoric acid amide Is formed and forms a thicker expansive char layer as compared with the case where these flame retardants are used singly, effectively suppressing the transfer of heat and oxygen required for combustion of the material.

In the present invention, the organic phosphate compound is preferably used in an amount of 1 to 20% by weight, more preferably 2 to 15% by weight. If the content of the organic phosphate-based flame retardant is less than 1% by weight, the problem of dripping, which is a problem in the conventional combustion, can not be solved. If the content is more than 20% by weight, the mechanical properties are deteriorated Can not do it.

In the present invention, the content of the melamine-based flame retardant of melamine or melamine derivative is preferably 5 to 50 wt%, more preferably 15 to 30 wt%. If the content of the melamine-based flame retardant is less than 5% by weight, the flame-retardant property may be deteriorated due to the inability to form an effective expandable charge at the time of combustion. If the content exceeds 50% by weight, the mechanical properties may be deteriorated.

The particle size of the flame retardant used to increase the flame retardancy of the plastic resin is also very important because the particle size of the flame retardant greatly affects the physical properties of the final flame retardant resin. It is generally known that the use of a flame retardant having a small particle size results in better physical properties and flame retardancy, and it is preferable to use a flame retardant having a particle size of 1 to 40 탆, more preferably a flame retardant having a particle size of 1 to 10 탆 .

The flame retardant thermoplastic polyurethane of the present invention may further comprise at least one additive selected from the group consisting of antioxidants, light stabilizers, lubricants, reinforcing agents, pigments, colorants and plasticizers in addition to the above-mentioned flame retardants. The additive may be used in a range that does not substantially adversely affect the physical properties according to the present invention.

The flame retardant thermoplastic polyurethane composite resin according to the present invention can be produced by using devices capable of effectively dispersing the flame retardant in the thermoplastic polyurethane resin at a temperature higher than the melting point of the thermoplastic polyurethane resin. Generally, the melting point of a thermoplastic polyurethane resin has a temperature of 150 to 250 DEG C and this melting point is determined by the thermoplastic polyurethane resin used. As a device for dispersing the flame retardant in the resin, a mixer such as a Banbury mixer, a roll mill, a continuous kneader, a single screw extruder and a twin screw extruder can be used. In consideration of melt kneadability and productivity, Is a twin-screw extruder. Particularly, when a device capable of increasing the melt-kneading property of the twin-screw extruder, that is, a kneading element and a stationary element, is used, a superior effect can be obtained.

In the present invention, a thermoplastic polyurethane resin and a non-halogen flame retardant were melt-kneaded using a twin-screw extruder, and the melt from the extruder die was cooled in a cooling bath and made into a pellet form. The thus prepared non-halogen flame retardant thermoplastic polyurethane composition was injection-molded using an injection molding machine, sufficiently stabilized at room temperature, and various mechanical properties and flame retardancy were evaluated.

As a result, the flame retardant thermoplastic polyurethane resin composition according to the present invention is expected not only to have excellent flame retardancy but also significantly improve flame retardant durability during combustion, and also to have excellent mechanical properties, which is expected to be very useful for wire insulation and vehicle interior materials.

Hereinafter, the present invention will be described in detail by way of examples, but the scope of the present invention is not limited by these examples.

Example  1 to 5 and Comparative Example  1-2

The thermoplastic polyurethane resin used in the present invention was a poly (tetramethylene) glycol (having a number average molecular weight of 1000) with a raw material metering device attached thereto and a continuous block extruder (Werner & Pfleiderer ZSK 58 twin screw extruder) ), 4,4'-methylenediphenyl diisocyanate and 1,4-butanediol were charged in the amounts shown in Table 1, respectively, and the thermoplastic polyurethane resin was polymerized at a reaction temperature of 190 to 220 ° C. The number of screw revolutions (rpm) was 300, and the catalyst used was 150 ppm of dibutyltin dilaurate. The thermoplastic polyurethane resin polymerized in the continuous reaction extruder was made into a chip form by using a pelletizer and dried at 70 ° C for 5 hours using a dehumidifying dryer (Conair SC60, inlet air dew point = -50 ° C) Followed by drying to obtain a thermoplastic polyurethane resin.

(1) The thermoplastic polyurethane resin obtained therefrom was titrated to determine the content of active isocyanate groups as follows. The results are shown in Table 1 below.

115 ml of DMF was added to 50 ml of a 2N amine and DMF solution, 25 g of a thermoplastic polyurethane resin was charged, the thermoplastic polyurethane resin was completely dissolved at a temperature of 80 to 90 캜, isopropyl alcohol was added thereto The following indicator was added and titrated with 1N hydrochloric acid to determine the active isocyanate content of the thermoplastic polyurethane resin.

(2) The melt index of the thermoplastic polyurethane resin was measured using an MI indexer (Daven Port) as follows, and the results are shown in Table 1 below.

The thermoplastic polyurethane resin was dried in a vacuum oven at 60 ° C. for 4 hours, then placed in an MI indexer, preheated at 210 ° C. for 5 minutes, pressed for 5 minutes at a load of 5000 g, Were measured.

Example  6-12 and Comparative Example  3 to 4

The thermoplastic polyurethane resin obtained by reacting poly (tetramethylene) glycol (number average molecular weight: 1000), 4,4-methylenediphenyl isocyanate and 1,4-butanediol in a weight ratio of 62.11: 32.30: 5.59, The water content, the active isocyanate group content, and the water solubility index were measured in the same manner as in Example 1, except for drying according to the indicated drying conditions. The results are shown in Table 2 below.

As can be seen from Tables 1 and 2, the thermoplastic polyurethane resin obtained from the process conditions out of the equivalence ratio and the drying temperature of each component used in the production of the thermoplastic polyurethane resin according to the present invention, It has been found that the content has an active isocyanate content of 0.1-1 wt%, which is in the range of the present invention, or has a significantly high moisture content.

Comparative Examples 5 to 6 and Examples 13 to 16

The melts were melt-kneaded at 170 to 200 DEG C using a twin-screw extruder according to the composition shown in Table 3, and the melt from the extruder die was cooled in a cooling bath to prepare pellets. The thermoplastic polyurethane composition thus obtained was used to prepare test specimens using an injection molding machine, and after sufficient stabilization, physical properties and flame retardancy were measured according to the following measuring method, and the results are shown in Table 3 below.

The mechanical properties such as tensile strength and elongation were measured according to the ASTM D412 method, and the tensile strength and elongation at break were measured. The flame retardancy was 3 mm in thickness, 12.7 mm in width , And 127 mm length specimens were used to measure flame retardancy. In addition, the number of droplets was measured during UL 94 rod vertical combustion test.

As shown in Table 3, the non-halogen flame retardant thermoplastic polyurethane resin composition containing a thermoplastic polyurethane resin containing a large amount of active isocyanate groups is relatively excellent in mechanical properties and flame retardancy, and it can be confirmed that the dripping phenomenon during combustion is improved.

As described above, the non-halogen flame retardant thermoplastic polyurethane composite resin composition according to the present invention is expected to be very useful for electric wire insulators and materials for automobile interior materials because flame retardancy and spark dripping performance are improved.

Claims (9)

1 to 20% by weight of an organic phosphate-based flame retardant as a flame retardant and 5 to 49% by weight of a melamine or a melamine derivative are contained in 50 to 80% by weight of a thermoplastic polyurethane resin containing 0.1 to 1% by weight of an active isocyanate group, The equivalent ratio (NCO / OH) of the isocyanate groups to the hydroxyl groups of the diol and the polyol as chain extender used in the production of the thermoplastic polyurethane resin is 1.01 to 1.10, Wherein the thermoplastic polyurethane resin is manufactured by drying at 40 to 100 ° C for 2 to 10 hours. delete delete The composite resin composition according to claim 1, wherein the thermoplastic polyurethane resin has a water content of 0 to 1000 ppm. The composite resin composition according to claim 1, wherein the organic phosphate-based flame retardant is trialkyl phosphate or triaryl phosphate. The composite resin composition according to claim 1, wherein the melamine derivative is melamine cyanurate, melamine phosphate, melamine polyphosphate or melamine borate. The composite resin composition according to claim 1, wherein the organic phosphate-based flame retardant is a powder or liquid phase having a particle size of 1 to 40 탆. The composite resin composition according to claim 1, wherein the melamine or melamine derivative is a powder having a particle size of 1 to 40 탆. A product molded from a halogen-free thermoplastic polyurethane flame retardant composite resin comprising the composite resin composition of any one of claims 1 to 8.