WO2003089442A1

WO2003089442A1 - A method of preparing phosphoric ester

Info

Publication number: WO2003089442A1
Application number: PCT/KR2002/000739
Authority: WO
Inventors: Sang-Ha Kim; Duk-Suk Jung; Dong-Kyung Park; Jong-Ho Park
Original assignee: Songwon Industrial Co., Ltd.
Priority date: 2002-04-22
Filing date: 2002-04-22
Publication date: 2003-10-30
Also published as: AU2002308823A1

Abstract

Disclosed is a method of preparing phosphoric ester. In this method, 4,4’-biphenol reacts with phosphorus oxychloride in the presence of metal halide, and the reactants react with phenol. The amount of phosphorus oxychloride is equal to or more than 1.5 moles per 1 mole of 4,4’-biphenol, and the amount of phenol is 1 to 1.5 moles per 1 mole of chlorine in the reactant.

Description

A METHOD OF PREPARING PHOSPHORIC ESTER

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a method of preparing a phosphoric ester compound, and more particularly, to a method of preparing a phosphoric ester compound that imparts good flame retardation to resin, has good compatibility with resin, and exhibits good heat-resistance and hydrolysis-resistance.

(b) Description of the Related Art As flame-retardants for resins, inorganic-type, organic halogen-type, and organic phosphor-type flame-retardant compounds are widely known. Because of poor flame-retardation of the inorganic-type flame-retardant compounds, a substantial amount thereof is required, resulting in the deterioration of the inherent properties of the resin. And even though the organic halogen-type flame-retardant compound has good flame-retardation, it has a drawback in that the compound thermally decomposes to generate hydrogen halide. The hydrogen halide causes contamination to moldings and generates human-harmful gas when the forming material is combusted. Therefore, the organic phosphor-type flame-retardant compound has recently gleaned attention.

The exemplary of the organic phosphor-type flame-retardant compounds may be monomer-type flame-retardants such as triphenyl phosphate and tricresol phosphate. However, the low boiling point of these compounds because of their low molecular weight causes them to be easily volatilized, thereby contaminating moldings and reducing working efficiency. In order to solve such problems, oligomer-type condensation organic-phosphor flame-retardants such as phenol resorcinol polyphosphate or a bisphenol-A polyphosphate which is cross-linked with a moiety of 2,2-bis(4-hydroxyphenyl)propane (hereinafter, "bisphenol-A") have been developed. The compound imparts flame-retardation to resin that is as good as that from monomer-type organic phosphor flame-retardants, and the high-molecular weight of the compound does not readily give rise to evaporation.

As the condensation organic-phosphor flame-retardants, phenol bisphenol-A polyphosphate is widely used, owing to its good hydrolysis-resistance and durability compared with phenol resorcinol polyphosphate. The phenol bisphenol-A polyphosphate has good heat-resistance, and is represented by the following formula A (Japanese Patent Laid-open No. Hei. 7-258539).

Rl — — 3 (A)

(wherein n is an integer of 0 to 10, R1 to R4 groups are independently phenyl, tolyl, or xylyl; and if n is equal to or more than 2, at least two R4 groups are the same or different.)

However, the compound represented by formula A still causes contamination of the moldings, which is a severe problem in a continuous forming procedure. In particular, when the oligomer represented by formula A is applied to engineering plastics of which a molding process is performed at a high temperature, such as a polycarbonate resin, the side reaction that occurs (breakage of backbone of bisphenol A) generates monomers such as triphenyl phosphate or isoprophenyl phosphate which causes contamination of the moldings, and furthermore, isoprophenyldiphenyl phosphate has shortcomings in that this unsaturated group provides poor light-resistance to the resin as well as the contamination.

In addition, the phenol bisphenol-A polyphosphate has a low phosphor content which necessitates an increase in the amount used in order to exhibit flame retardation.

Japanese Patent Laid-Open No. Hei. 5-1079 teaches an aromatic diphosphate (resorcinol bis (di-2,6-methylphenylphosphate)) exhibiting good heat-resistance. The compound is a high-purity compound in which moieties at the 2- and 6-positions are substituted with alkyl group-containing monohydric phenol. However, the rigid structure at the 2- and 6-positions decreases compatibility with the resin and deteriorates forming processing.

The heat-resistance of the flame-retardant compound is derived from a dihydric phenol combined with phosphor (aromatic dihydroxy compound) rather than a monohydric phenol. The mono-ring resorcinol has shortcomings such as poor heat-resistance and hydrolysis-resistance, and bisphenol A of formula A with relatively good heat-resistance has drawbacks such as the breakage of the structure. WO 99/55771 discloses a method of making phenol bisphenol-A polyphosphate by continuously reacting a phosphorus oxychloride with bisphenol A. WO 00/77012 discloses that bisphenol A is added to a mixture of excess phosphorus oxychloride and a catalyst at 85-106 ^°C , and phenol is

added to the resulting mixture. The procedure can prepare a product with high purity (n=1), and low triphenylphosphate and isopropanylphenyldiphenylphosphate contents as impurities. However, this patent cannot completely solve the shortcomings caused by the side product derived from the bisphenol A.

Japanese Patent Laid-open No. Hei. 5-1079 discloses that a method of preparing a high-purity aromatic diphosphate in which moieties at the 2- and 6-positions are substituted with alkyl group-containing monohydric phenol. This method is that monohydric phenol reacts with phosphorus oxyhalide in the presence of a Lewis acid catalyst to obtain high-purity diarylphosphorohaloridate, and diarylphosphorohaloridate reacts with an aromatic dihydroxy compound in the presence of the Lewis acid catalyst to prepare a high-purity aromatic diphosphate in the form of crystalline powder.

The method disclosed in Japanese Patent Laid-open No. Hei. 5-1079 is that an aromatic monohydroxy compound reacts with phosphorus oxyhalide in the presence of a Lewis acid catalyst to prepare diarylphosphorohaloridate, and the diarylphosphorohaloridate reacts with an aromatic dihydroxy compound in the presence of the Lewis acid catalyst to prepare an aromatic diphosphate. The resulting aromatic diphosphate is an organic phosphoric ester with good heat-resistance, in which moieties at the 2- and 6-positions are substituted with an alkyl group-containing monohydric phenol. However, the rigid structure at the 2- and 6-positions decreases compatibility with the resin and deteriorates forming processing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of preparing an oligomer-type phosphoric ester that imparts good flame-retardation to resin, and does not deteriorate heat-resistance of the resin, that exhibits good hydrolysis-resistance and low volatilization, and that does not generate a bad external appearance of the resulting forming material, such that it is useful as a non-halogen flame-retardant.

Another object of the present invention is to provide a method of preparing a phosphoric ester compound with a low triphenyl phosphate content and low volatilization components, and which does not produce a half ester deteriorates the performance of the resin. These and other objects may be achieved with a method of preparing an oligomer-type phosphoric ester compound represented by the following formula 1 , including reacting 4,4'-biphenol with phosphorus oxychloride in the mole ratio of 1 : 1.5 or more in the presence of a metal halide, and reacting the resulting product with phenol, the amount of phenol being more than the theoretical amount to chlorine in the resulting product.

(wherein n is an integer of 1 to 5).

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method of preparing an oligomer-type phosphoric ester compound represented by the following formula 1 with a desirable molecular weight, which has good compatibility with resin and a low triphenyl phosphate (TPP) content, without the production of a half ester with hydroxyl group derived from 4,4-biphenol which causes the deterioration of the properties of resin.

0

O

(wherein n is an integer of 1 to 5) In the application, a half ester is defined as a compound in which one OH group of two OH groups in a biphenol is substituted with another functional group, and the other OH is not substituted.

The method of the present invention can prepare phosphoric ester compounds in the form of a mixture, in which one compound with the value of n of 1 , 2, 3, 4, or 5 is suitably mixed with another compound with the value of n of 1 , 2, 3, 4, or 5, and the mixed phosphoric ester compounds provide good compatibility with resin and forming processing. In addition, the phosphoric ester compound has low volatilization, and good flame-retardation, heat-resistance, and hydrolysis-resistance.

The present invention will be illustrated in more detail.

4,4'-biphenol reacts with phosphorus oxychloride in the presence of metal halide as shown in the following reaction formula 1 (Step 1).

0

Cl II

^> P--0-/θV-( C)Vθ-P Cl+2n HC1

Cl n

Cl (1) The 4,4'-biphenol may use any compound which is readily available, and it is understood that it is not limited.

The metal halide acts as a catalyst. The exemplary of the metal halide may be magnesium chloride, aluminum chloride, zinc chloride, titanium tetrachloride, or boron trifluoride. A mixture thereof may be also used as the metal halide. Preferred are magnesium chloride and/ or aluminum chloride, and most preferred is magnesium chloride.

The amount of phosphorus oxychloride is 1.5M or more to 1 M of 4,4'-biphenol.

Such an excess amount of phosphorus oxychloride allows an increase in the produced amount of aromatic diphosphate (4,4-biphenol bis(diphenylphosphate) with an n of 1 and a reduction in the produced amount of a compound with an n of 2 or more, which reduces the boiling point of the resulting product and increases purity.

However, too large an amount of phosphorus oxychloride causes a large amount of the unreacted phosphorus oxychloride to remain, so that the amount of phosphorus oxychloride is preferably 1.5 to 10M to 1 M of 4,4'-biphenol, and more preferably 1.5 to 5M.

If the amount of phosphorus oxychloride is less than 1.5M to 1 M of

4,4'-biphenol, all phosphoric ester compounds with the value of n of 1 , 2, 3, 4, and 5 at the proportional ratio are prepared, which results in a decrease in the desired properties, and an increase in viscosity which causes difficulty in handling.

The excess of phosphorus oxychloride also acts as a solvent, which eliminates the requirement for solvent. The reaction of step 1 is performed at 70 to 150^°C , and preferably 80

to 120°C . If the reacting temperature is less than 70 ^°C , the reaction is not

completed. If the reacting temperature is more than 150^°C, esterification

occurs, thereby enlarging the component distribution of the phosphor ester compound.

The reacting time of step 1 depends on the reacting conditions such as temperature, and is generally about 2 to 5 hours.

After the completion of the reaction of step 1 , unreacted phosphorus oxychloride is removed. The unreacted phosphorus causes a problem regarding the production of triphenyl phosphate to occur due to it's reaction with phenol.

The unreacted phosphorus oxychloride with its low volatilization properties is readily removed by evaporating under a reduced pressure. The evaporation is preferably performed at a temperature of about 100 to 150 ^°C at a pressure of 10kPa or less, and preferably at 5 to 1 kPa.

Thereafter, the resulting product reacts with phenol, as shown in the following reaction formula 2 (Step 2).

The amount of phenol is 1-1.5M to 1 M of chlorine in the resulting product obtained from the step 1 , and preferably 1.01 to 1.2M. If the total resulting product is 4,4-biphenol bis(diphόsphorochloridate) in which n is 1 , the amount of phenol is desirably 4-6M to 1 M of the resulting product.

If the amount of phenol is less than 1 M to 1 M of chlorine in the resulting product, the reaction is not completed, and the unreacted chlorine iremains in the resulting product. If the amount of phenol is more than 1.5M, the produced phenol 4,4'-biphenol polyphosphate is substituted with phenol groups, thereby producing triphenyl phosphate with low volatilization.

The reaction of the step 2 is preferably performed at 100 to 200 ^°C , and

more preferably at 110 to 160 ^°C . If the reacting temperature is less than

100^°C, the reaction does not readily occur. If the reacting temperature is

more than 200 ^°C , esterification occurs, thereby producing triphenyl

phosphate.

The reacting time of the step 2 depends on the reaction conditions such as temperature, and is generally 3 to 8 hours.

At the end of the step 2, the reacting system is preferably set to a reduced pressure, or under an inert atmosphere such as with nitrogen gas, to remove hydrogen chloride as a side product.

In the step 2, a problem occurs which is caused by extracted crystals of the evaporated phenol, in which the extracted crystals is adhered within reaction devices such as a bath or condenser to block the reaction device. Such a problem is addressed by using an inert solvent in the step 2.

The reaction of the step 2 is preferably performed while the inert solvent is refluxed. The solvent may be an organic solvent such as toluene, xylene, or chlorobenzene, and the amount of the solvent is about 5 to 50 wt% to phenol. The product obtained from the step 2 may be used as a flame-retardant for resin, by removing the low volatility components such as solvent and excess (unreacted) phenol with a conventional technique, such as by evaporation under a reduced pressure, or by vapor evaporation (which

is performed at a temperature of about 120 to 160 ^°C and a pressure of 8kPa

or less).

Prior to the evaporation under the reduced pressure, the resulting mixture may be washed with water, or with organic solvents such as toluene, xylene, or chlorobenzene. The temperature of water or the organic solvent, or the resulting mixture, may be varied according to the composition of the resulting product, and the shortcomings in which a compound with the value of n of 1 mainly extracted are overcome by adjusting the temperature to preferably about 70 to 90 ^°C.

In addition, the reacting product may be desirably recrystallized using a mixed solvent such as a mixture of methanol and water, or ethanol and water.

The metal components and the oxide components which remain in the reacting products derived from the raw materials (4,4'-biphenol, phosphorus oxychloride, phenol), catalyst (metal halide), and solvent, and which deteriorate properties of the resin, are preferably removed by general techniques. The removal procedure may use an acid wash, an alkali wash, evaporation under a reduced pressure, or recrystallization.

A wash with acid can remove the metal components from the reacting product. The preferable acid is a diluted aqueous solution of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, or citric acid. A wash with alkaline can remove the acid components from the reacting product. The preferable alkaline is a diluted aqueous solution of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, or sodium hydrogencarbonate.

According to the preparation of the present invention, a mixture of the aromatic diphosphate (4,4'-biphenol bis(diphenylphosphate)) in which n is 1 in formula 1 , and compounds (phenol 4,4'-biphenol polyphosphate) in which n is 2, 3, 4, or 5, is obtained. The ratio of the compound in which ή is 1 , and the compounds in which n is 2, 3, 4, or 5 is varied from the preparing condition, but in the phosphoric ester compound represented by formula 1 of the present invention, 4,4'-biphenol bis(diphenylphosphate) in which n is 1 , is a main component. The final product may include a trace of a compound in which n is 0 (triphenyl phosphate) as an impurity.

The oligomer-type phosphoric ester compound represented by formula 1 of the present invention imparts good flame-retardation to resin, and has low volatilization, good compatibility with resin, and good forming processing. The backbone structure of the compound provides good heat-resistance. In addition, the compound has good hydrolysis-resistance, it does not deteriorate mechanical strength of the resin, and it is inexpensive. The phosphoric ester compound is useful as a flame-retardant in a resin composition. Furthermore, the phosphoric ester compound does not facilitate the contamination of moldings and does not provide a bad external appearance of the resulting forming material.

If the phosphoric ester compound of formula 1 is prepared in the form of a solid at room temperature, the amount of phosphorous oxychloride is sufficiently controlled to obtain a resulting product with at least 70% of the compound in which n is 1. The phosphoric ester compound of formula 1 has a melting point of 70 to 89 ^°C .

The phosphoric ester compounds of the present invention may be useful as flame-retardants in resin compositions such as a thermoplastic resin, or a thermosetting resin.

An example of the thermoplastic resin may be polyphenylene ether-based resin (e.g. modified polyphenylether (modified PPE)), polyethylene, polypropylene, polystyrene, impact-resistant polystyrene, ACS resin, AS resin, ABS resin, polycarbonate, polyamide, polyimide, polymethylmethacrylate, polyphenylene sulfate, polyether ether ketone, polyether sulfone, polysulfone, polyarylate, polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyacetal, polyetherketones, polyethernitrile, polythio ethersulforane, polybenzimidazole, polycarboxyl imide, liquid crystalline polymer and polymer blend thereof, and polymer alloy (e.g. PC/ABS polymer-alloy).

The thermosetting resin may be polyurethane, phenol resin, melamine resin, urea resin, epoxy resin, unsaturated ester, diarylphthalate resin, polymer blend thereof, and polymer alloy. The amount of the phosphoric ester compound of the present invention is suitably adjusted according to the resin type, or the required flame-retardation, and is generally 1 to 50 parts by weight based on 100 parts by weight of the resin. The phosphor ester compound of the present invention, or alternatively with various additives, is added to the resin, and it is mixed by the general techniques followed by melt-mixing to prepare a flame-retardant resin composition.

The various additives may be other flame retardants, flame-retardant aids, an agent for preventing dripping, a filler, an antioxidant (stabilizer), an antistatic agent, a softening agent, a pigment, an ultraviolet ray absorbent (photo stabilizer), and a reinforcement agent.

The resin composition is formed by the general techniques to produce a forming material. The following examples further illustrate the present invention, but the invention is not limited by these examples. (Example 1)

186.2g (1 M) of 4,4-biphenol, 767.5g (5.0M) of phosphorous oxychloride, and 1.5g of anhydrous magnesium chloride were charged into a 1 L four-neck flask with a stirrer, a refluxing tube, and a thermometer. The resulting mixture was heated to 120^°C for 2 hours while shaking, under a

nitrogen atmosphere.

Thereafter, the resulting mixture was shaken at the same temperature (120^°C) for 1 hour to facilitate the reaction. The pressure was reduced to

about 1.5kPa for 120 ^°C to recover excess phosphorus oxychloride.

The reacted mixture was cooled to about 80 ^°C , and 371.0g (3.95M) of

phenol which corresponded to 2% more than the remaining chloride percentage, and 30g of toluene, were added to the cooled mixture. The obtained material was heated to 150^°C for 2 hours while shaking under a

nitrogen atmosphere, and the heated material was reflux-reacted at the same temperature (150^°C) under a reduced pressure (about 120kPa) for 2 hours.

The reaction solution was cooled to 100^°C or less, and nitrogen gas

was injected into the flask to control the inner pressure of the flask to ambient pressure. 100g of toluene was then added to the reaction material, and the resulting mixture was washed with 3.5% hydrochloric acid and 1% sodium hydroxide at 80 ^°C , sequentially.

The washed material was steam distilled at 120^°C under the reduced

pressure (about 2.7kPa) to remove low boiling-point components from the material. The resulting material was cooled and solidified to obtain 623g of

a product with a melting point of 79 to 82 ^°C (crude fraction based on the

compound in which n is 1 in formula 1 : 95.8%).

The composition (area %) of the product was determined by liquid chromatography.

Composition:

In formula 1 , n=1 84.5% n=2, 11.5% n=3-5 3.5% triphenyl phosphate (TPP)(n=0) 0.5%

The phosphor content in the product was measured. Phosphor content: 9.5%

The results and the mole ratio of phosphorus oxychloride and 4,4'-biphenol are presented in Table 1. (Example 2) 637g of a product with a melting point of 80-84 ^°C (crude fraction

based on the compound in which n is 1 in formula 1 : 98.0%) was prepared by the same procedure as in Example 1 , except that 1 ,074g (7.0mol) of phosphorus oxychloride was used. Composition:

In formula 1 , n=1 91.5% n=2 6.3% n=3-5 2.2% triphenyl phosphate (TPP)(n=0) 0.0% The phosphor content in the product was measured. Phosphor content: 9.54% The results and the mole ratio of phosphorus oxychloride and

4,4'-biphenol are presented in Table 1. (Example 3) 611g of a light brown product that is liquid at room temperature (crude fraction based on the compound in which n is^' 1 in formula 1 : 94.0%) was prepared by the same procedure as in Example 1 , except that 383.8g (2.5M) of phosphorus oxychloride was used.

Composition:

In formula 1 , n=1 68.8% n=2, 23.0% n=3-5 7.7% triphenyl phosphate (TPP) (n=0) 0.5%

The phosphor content in the product was measured. Phosphor content: 9.6%

The results and the mole ratio of phosphorus oxychloride and 4,4'-biphenol are presented in Table 1. (Comparative Example 1)

605g of a light brown-liquid product having adherence and high viscosity (crude fraction based on the compound in which n is 1 in formula 1 : 93.0%) was prepared by the same procedure as in Example 1 , except that 184.2g (1.2M) of phosphorus oxychloride was used. The product included all compounds in which the values of n were 1 , 2,

3, 4, and 5, and that were considered to be polymers. The product included 9.5 wt% of a half ester with hydroxyl groups, in which 4,4'-biphenol was not esterificated. The results and the mole ratio of phosphorus oxychloride and 4,4'-biphenol are presented in Table 1. (Comparative Example 2)

186.2g (1 M) of 4,4'-biphenol, 385.4g (4.1 M: 2.5% excess over the theoretical amount) of phosphorus oxychloride, and 1.5g of anhydrous magnesium chloride were charged into a 2L four-neck flask with a stirrer, a refluxing tube, and a thermometer. The mixed solution was shaken under a

nitrogen atmosphere and heated to 120^°C for 2 hours while shaking.

, The resulting solution was shaken at the same temperature (120^°C)

for 1 hour to facilitate the reaction. The reaction solution was compressed to 1.5kPa at 120 °C to recover excess phosphorus oxychloride.

Using the resulting solution, the procedure was performed in the same way as in Example 1 to obtain 603g of a light brown liquid product having adherence and high viscosity (crude fraction based on the compound in which n is 1 in formula 1 : 92.7%).

The product included 21.5 wt% of low-molecular weight triphenyl phosphate (TPP) and all compounds in which n is 1 , 2, 3, 4, and 5, in formula 1. The product also included 25.55 wt% of a half ester with hydroxyl groups in which two end groups in 4,4'-biphenol were not esterificated. The results and the mole ratio of phosphorus oxychloride and

4,4'-biphenol are presented in Table 1.

(Comparative Example 3)

619g of a product with a melting point of 83 ^°C (crude fraction based on the compound in which n is 1 in formula 1 : 95.2%) was prepared by the same procedure as in Example 1 , except that the recovering of excess

phosphorus oxychloride was performed at 130^°C under ambient pressure. .

The product included 7.5% of low-molecular weight triphenyl phosphate (TPP), which is a larger amount than in Example 1.

The results and the mole ratio of phosphorus oxychloride and 4,4'-biphenol are presented in Table 1. (Comparative Example 4)

186.2g (1 M) of 4,4'-biphenol, 307g (2.0M) of phosphorus oxychloride, 376g (4.0M) of phenol, and 1.5g of anhydrous magnesium chloride were charged into a 2L four-neck flask with a stirrer, a refluxing tube, and a thermometer. The resulting mixture was heated to 120^°C for 2 hours while

shaking under a nitrogen atmosphere, and then it was again heated to 150^°C

followed by shaking at this temperature for 1 hour. It was confirmed by G/C analysis that unreacted phenol did not remain in the resulting product.

The reaction solution was compressed to about 1.5kPa at 120^°C to

remove excess phosphorus oxychloride, thereby obtaining 527g of a product (crude fraction based on diphenylphosphorochloridate was 98%).

The composition of the product was measured by G/C analysis (area%) and the results showed that the product included 13.0% monophenyl phosphorochloridate, 79.0% of diphenylphosphorochloridate, and 8.0% of triphenyl phosphate. The reaction solution was cooled to about 80 ^°C , and 186.2g (1 M) of

4,4'-biphenol, which corresponded to 2% more than the remaining chlorine

was added to the cooled solution. The mixed solution was heated to 150^°C

for 2 hours, while shaking under a nitrogen atmosphere. The resulting

solution was allowed to stand at the same temperature such as 150^°C under

a reduced pressure (about 20kPa) for 2 hours.

Using the obtained solution, after it was cooled to 100^°C or less, the

following procedure was performed in the same was as in Example 1. 100g of toluene were added to the cooled solution, and the mixture was washed with a 3.5% aqueous solution of hydrochloric acid and a 1 % aqueous solution

of sodium hydroxide at 80 ^°C .

The washed product was steam distillated at 120^°C under reduced

pressure, and it. was cooled and solidified to obtain 604g of a semi-solid product (crude fraction based on the compound in which n is 1 : 92.9%). The obtained product included 8.5% of low molecular weight triphenyl phosphate (TPP), which is a larger amount than in Example 1 , and included

3.5% of half ester with hydroxyl groups, in which two end functional groups of

4,4'-biphenol were esterificated.

The results and the mole ratio of phosphorus oxychloride and 4,4'-biphenol are presented in Table 1. Mole ratio:

Examples 1 to 3, Comparative Examples 1 to 3: used mole ratio of 4,4'-biphenol/ phosphorus oxychloride

Comparative Example 2 (simultaneous reaction): used mole ratio of 4,4'-biphenol/ phenol/ phosphorus oxychloride

Comparative Example 4 (reverse reaction): used mole ratio of 4,4'-biphenol/diphenylphosphorochloridate

TPP: triphenyl phosphate Extra: in the composition with n being 1 to 5, a half ester with hydroxyl groups of 4,4'-biphenol (Table 1)

Table 1

As shown in Table 1 , the product according to Examples 1 to 3 included compounds with n being 1 , 2, 3, 4, and 5, and included the compound with n being 1 as a main component. The product had a low triphenyl phosphate (TPP) content, and it included no half ester with hydroxyl groups derived from 4,4'-biphenol by evaporating under the reduced pressure and removing unreacted phosphorus oxychloride.

Comparative Example 1 with the use of too small an amount of phosphorus oxychloride with respect to 4,4'-biphenol produced compounds in which the value of n is 1 , 2, 3, 4, and 5 at the substantially proportional ratio, thereby producing a large amount of half ester with hydroxyl groups derived from 4,4'-biphenol, which deteriorates properties of the resin.

In Comparative Example 2, 4,4-biphenol, phenol, and phosphorus oxychloride were simultaneously reacted, but this method produced compounds in which the value of n is 1 , 2, 3, 4, and 5 at a substantially more proportional ratio compared to Comparative Example 1 , and it produced a large amount of triphenyl phosphate (TPP) as well as half ester with hydroxyl groups derived from 4,4'-biphenol.

The product of Comparative Example 3 in which excess (unreacted) phosphorus oxychloride was removed under ambient pressure, included 7.5% of triphenyl phosphate (TPP), which is a larger amount than in Example 1.

Comparative Example 4 in which diphenylphosphorochloridate was previously prepared and then reacted with 4,4'-biphenol, produced a large amount of triphenyl phosphate during the preparation of diphenylphosphorochloridate, and the product included 3.5% of half ester with hydroxyl groups derived from 4,4'-biphenol.

Experiments 1 and 2, and Comparative Experiments 1 and 2 12 parts by weight of each of the phosphoric ester compounds according to Examples 1 and 2, and Comparative Examples 1 and 4 as the flame-retardant, and 0.4 parts by weight of polytetrafluoroethylene (PTFE) as an agent for preventing dripping based on 100 parts by weight of PC/ABS polymer alloy (Kaneda Corporation No. ALPHALOY MPC4601), were added to the polymer alloy.

The mixture was melt-mixed with a two-axis extruder to obtain a pellet. The pellet was formed by an injection molding to produce a sample for a flame-retardation (vertical firing) test and a sample for a mechanical test, and the physical properties were measured by the following test procedures. The results, the mixed components of the resin composition, and the mixing ratio are presented in Table 2.

(1) Resin flame-retardation (UL) test

Test procedure: based on UL-94 (5 Average firing time) Sample: thickness 1.6mm Evaluation: According to unit, lank V-0, V-1 , and V-2

(2) Weight loss by heating

Pellets (Diameter: about 2mm; length: about 3mm; weight: about

10mg) were heated to 300 ^°C at the increasing rate of 20 ^°C/ minute by using an open cell and a thermal analyzer under a nitrogen atmosphere, and the percent of the decreased weight (weight %) was measured.

(3) Fluidity test

The resin compositions were dried under a predetermined condition to measure the MFR (melt mass-flow rate).

Sample: resin pellet (diameter: about 2mm; length: about 3mm) Drying condition: 95 ^°C , 3 hours

Measuring method: based on JIS K-7210 Measuring condition: PC/ABS: 230 ^°C , load 5.0kg

Unit: g/10 minutes

(4) Hydrolysis-resistance

75g of each of the flame-retardant compounds and 25g of distilled water were added to respective bottles, which were tightly sealed with Teflon tape followed by heating at 95 ^°C for 48 hours in an incubator. After the

completion of hydrolysis, a water layer was separated and the separated water layer was titrated with an N/10 NaOH solution to measure total acidic value in the water layer.

(5) Flaming test

While the resin composition pastes were molded, the flaming occurrence was observed by eye. The symbol "O" refers to no occurrence of flaming and the symbol "X" refers to occurrence of flaming. (Table 2)

It is shown from Table 2 that the resin composition with flame-retardant compounds according to Experiments 1 and 2 exhibited excellent flame-retardation. Furthermore, the resin composition exhibited good bending strength, bending elasticity, HDT, low volatilization (low weight loss) compared to Comparative Experiments 1 and 2 (Comparative Examples 1 and 4).

The flame-retardant compound used in Comparative Experiment 1 including all phosphoric ester compounds in which n is 1 , 2, 3, 4, and 5 at the proportional ratio and including half ester (9.5%) with hydroxyl groups derived from 4,4-biphenol reduced the molecular weight of the resin (PC), thereby deteriorating mechanical strength, volatilization, hydrolysis, and flame-retardation qualities.

The flame-retardant compound used in Comparative Experiment 2 including triphenyl phosphate (TPP) (8.5%) and 3.5% of half ester with hydroxyl groups derived from 4,4'-biphenol deteriorated properties of the resin as in like Comparative Experiment 1.

As described above, the resin composition with the flame-retardant compound of the present invention exhibited good flame-retardation, bending strength, bending elasticity, HDT, and low volatilization, compared with the conventional flame-retardant compound.

The flame-retardant compound of the present invention has good compatibility with resin, low triphenyl phosphate content, and no half ester with hydroxyl groups derived from 4,4'-biphenol.

A resin composition with the oligomer-type phosphoric ester compound obtained from the procedure of the present invention exhibits good flame-retardation, good heat-resistance because of the structure

(4,4'-biphenol), good hydrolysis-resistance, and low volatilization, and does not contaminate moldings.

Claims

What is claimed is:

1. A method of preparing an oligomer-type phosphoric ester compound represented by following formula 1 , comprising: reacting 4,4'-biphenol with phosphorus oxychloride in the mole ratio of 1 : 1.5 or more in the presence of metal halide to obtain a reacted material; reacting the reacted material with phenol, the amount of phenol being 1 to 1.5M based on 1 M of chlorine in the reacting material.

(wherein, n is an integer of 1 to 5).

2. The method of claim 1 , wherein the metal halide is magnesium chloride and/ or aluminum chloride.

3. The method of claim 1 , further comprising removing unreacted phosphorus oxychloride, after the reaction between 4,4'-biphenol and phosphorus oxychloride.

4. The method of claim 3, wherein the removing is performed under a reduced pressure.

5. The method of claim 1 , wherein the reacting of the reacted material with phenol is performed in unreactive organic solvent.

6. The method of claim 1 , wherein the amount of phosphorus oxychloride is 1.5 to 10M based on 1 M of 4,4'-biphenol.

7. The method of claim 1 , wherein the amount of phenol is 1.01 to 1.2M based on 1 M of chlorine in the reacting material.