JPS6111973B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improving the color tone of polycarbonate resin that has been made flame retardant with a flame retardant made of a halogenated organic compound (hereinafter referred to as a halogen-based flame retardant). The present invention relates to a polycarbonate resin composition in which discoloration during melt molding is suppressed and the color tone is improved by blending a small amount of trimethyl phosphate into the polycarbonate resin. In recent years, there has been a strong demand for flame retardant polymer materials, and halogen elements are bonded to the molecular structure of polycarbonate resins themselves, or organic compounds containing halogen elements are used as flame retardants in polycarbonate resins. A blending technology has been developed to meet this demand. However, polycarbonate resin compositions made flame retardant by the addition of halogenated organic compounds undergo thermal decomposition due to the action of halogen generated by decomposition of the flame retardant during melt molding such as injection molding and extrusion molding. The resulting molded product is often discolored. In order to suppress such discoloration, methods of adding epoxy compounds, alkali (earth) metal carbonates, metal soaps, organic tin compounds, etc. have been proposed, but all of these have to be added in relatively large amounts. As a result, the optical properties and mechanical properties of polycarbonate resin molded articles tend to be impaired. As a result of extensive research into discoloration inhibitors that can eliminate the above-mentioned drawbacks for polycarbonate resin compositions made flame retardant with halogenated flame retardants, the present inventors found that
The present invention was achieved by discovering that a composition obtained by adding and mixing a small amount of trimethyl phosphate to the resin composition significantly suppresses discoloration when heated to a high temperature and melted. That is, the present invention provides a composition comprising a flame retardant made of a halogenated organic compound and a polycarbonate resin, and trimethyl phosphate in an amount of 0.001% or more and less than 0.1% by weight based on the total weight of the polycarbonate resin and the flame retardant. This is a flame-retardant polycarbonate resin composition. In the present invention, the halogenated organic compound has a chlorine atom and/or a bromine atom bonded in its molecular structure, and by adding and mixing it to a polycarbonate resin, the halogenated organic compound that makes the resin flame retardant can be added. The molecular weight thereof is generally less than about 5000, but is not particularly limited thereto. Among these halogenated organic compounds, examples of aromatic halides include:
hexabromobenzene, pentabromotoluene,
Brominated biphenyl, chlorinated triphenyl, brominated diphenyl ether tetrachlorophthalic acid, tetrabromo phthalic anhydride, tribromophenol,
Tribromophenyl, dibromoalkyl ether, tetrabromobisphenol S, tetrachlorobisphenol A, 2,2-bis(4-hydroxy-3,5-dibromophenyl)-propane (hereinafter referred to as tetrabromobisphenol A) ), dibromopropyl ether of tetrabromobisphenol A, aryl ether of tetrabromobisphenol A, condensation products of tetrabromobisphenol A and dibromoethane, polycarbonate of tetrabromobisphenol A, etc. Examples of halides include monoclopentabromocyclohexane, hexabromocyclododecane, perchloropentacyclodecane,
Examples of aliphatic halides include hexachloroendomethylenetetrahydrophthalic anhydride, chlorinated paraffin, chlorinated polyethylene,
Examples include tetrabromoethane, tetrabromobutane, tris (β-chloroethyl) phosphate, tris (dichloropropyl) phosphate, tris (dibromopropyl) phosphate, tris (chlorobromopropyl) phosphate, and the like. Among these halogenated organic compounds, aromatic or alicyclic halogen compounds are preferred, especially 2.2
-bis(4-hydroxy-3,5-dibromophenyl)propane or a derivative thereof is preferred. These halogenated organic compounds may be one or two types.
It is used as a halogen-based flame retardant by mixing two or more types of flame retardants, but it is often used in combination with other flame retardants (e.g., phosphorus-based flame retardants, sulfonic acid-based flame retardants, etc.), flame retardant aids ( For example, antimony, arsenic, boron, bismuth,
(Compounds containing elements such as selenium, tellurium, nickel, titanium, etc.) and smoke inhibitors (For example, compounds containing heavy metal elements such as iron, vanadium, manganese, etc.). Furthermore, if necessary, other stabilizers (for example, phosphite ester, dibutyltin maleate, alkali (earth) metal carbonate, epoxy compound, etc.) may be added. In the present invention, trimethyl phosphate is used as an inhibitor for discoloration of polycarbonate resin molded articles caused by halogens produced by thermal decomposition of flame retardants. Surprisingly, tributyl phosphate,
Other phosphoric acid esters such as trioctyl phosphate and triphenyl phosphate have almost no discoloration inhibiting effect. Since trimethyl phosphate has a pentavalent phosphorus, it can no longer be expected to have a reductive bleaching effect, and its boiling point is 180 to 195℃, so it
It was considered inappropriate to add it to polycarbonate resins molded at °C. It is a completely unexpected fact that such a compound would exhibit such an excellent discoloration inhibiting effect as the one of the present invention. Moreover, it is truly surprising that even when used in combination with a compound having a phosphate ester bond in its molecular structure, such as tris(chlorobromopropyl) phosphate, it exhibits an excellent discoloration inhibiting effect. The blending amount of trimethyl phosphate varies depending on the type and blending ratio of the polycarbonate resin and halogen flame retardant, but it is usually 0.001% by weight or more and less than 0.1% by weight based on the total weight of the polycarbonate resin and halogen flame retardant. , preferably 0.01 to 0.08% by weight. If it is less than 0.001% by weight, no discoloration inhibiting effect is observed, and if it is more than 0.1% by weight, the effect reaches saturation, so there is no point in adding a large amount. In producing the composition of the present invention, the most effective method is to blend the halogenated flame retardant and trimethyl phosphate after polymerization, purification, and other steps. There are no particular restrictions on the order and method of blending. tumbler mixer, super mixer,
Depending on the properties of the target halogen-based flame retardant, methods such as a method using a Nauta mixer, a Banbury mixer, a roll method, a method using melt extrusion, etc. may be selected as appropriate; It is preferable to blend the flame retardant into the polycarbonate resin and then blend it into the polycarbonate resin from the viewpoint of uniform blending. Of course, various additives commonly used in polycarbonate resins may be added to the composition of the present invention, such as
Colorants, lubricants, antistatic agents, fillers, reinforcing agents, etc. may be added. In the composition of the present invention, the restrictions conventionally imposed on blending a halogen flame retardant with a polycarbonate resin are greatly alleviated. For example, flame retardants that could not be used because they decompose at molding temperatures of 250 to 300 degrees Celsius and cause significant discoloration of molded products can now be used, or materials that could only be used in small amounts can now be used in large amounts. . Moreover, since discoloration during molding is suppressed, the commercial value of the molded product is improved, and in particular, the commercial value of dye-colored flame-retardant molded products, which have had many problems in the past, can be dramatically improved. As described above, the composition of the present invention is a flame retardant used in materials having a relatively high molding temperature, that is, a flame retardant that generally contains an aromatic or alicyclic halogenated organic compound. The effect is most pronounced when it is blended with. The present invention will be explained below with reference to Examples and Comparative Examples. The evaluation was carried out in the following manner. <Evaluation method for inhibition of discoloration> The pellets were molded into sample plates of 70 mm x 50 mm x 2 mm under predetermined conditions using an Ankerberg injection molding machine. In order to evaluate the degree of discoloration suppression, the hue (L', a', b') of a sample plate molded after residence in the cylinder of a molding machine for a predetermined time and the hue (L, a, b') of a sample plate molded without retention were determined. b) was measured using a color difference meter (manufactured by Color Machine Co., Ltd.), and the degree of discoloration was compared by ΔE=√(-') ² +(-') ² +(-') ² . Note that trimethyl phosphate used in the examples is an industrial reagent (manufactured by Daihachi Chemical). Examples 1 to 4 Comparative Examples 1 to 2 Polycarbonate powder L-1250P (manufactured by Teijin Kasei) made from bisphenol A with an average molecular weight of 25000,
A low polymer powder from the flame retardant tetrabromobisphenol A and trimethyl phosphate were mixed in the proportions shown in Table 1 using a super mixer, and the mixture was extruded into pellets using a 30 mm diameter extruder. This pellet was molded at a molding temperature of 340°C and evaluated using the method described above. The low polymer from tetrabromobisphenol A is a white powder with a degree of polymerization of about 4, which is polymerized by the phosgene method using a terminal capper, paratertiary butylphenol, in the presence of triethylamine as a catalyst.

[Table] Examples 5 and 6 Comparative Example 3 Flame retardant decabromodiphenyl ether (trade name FR-300BA, manufactured by Dow Chemical Company) was used in the blending ratio as shown in Table 2. The conditions and method were the same as in Examples 1 to 4 above.

[Table] Comparative Examples 4 to 6 In Example 1, the fifth
Pellets were molded in the same manner as in Example 1, except that the materials listed in the table were used, and the hue and degree of discoloration of sample plates molded from the pellets were measured. The results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1. A composition consisting of a flame retardant made of a halogenated organic compound and a polycarbonate resin is added with a total weight of the polycarbonate resin and the flame retardant.
A flame-retardant polycarbonate resin composition containing 0.001% by weight or more and less than 0.1% by weight of trimethyl phosphate. 2 Claim 1 in which the halogenated organic compound is an aromatic or dendritic halogenated organic compound
The polycarbonate resin composition described in . 3 The halogenated organic compound is 2,2-bis(4
The polycarbonate resin composition according to any one of claims 1 and 2, which is -hydroxy-3,5-dibromophenyl)propane or a derivative thereof. 4. Claims 1 to 3, wherein the amount of trimethyl phosphate is in the range of 0.01 to 0.08% by weight based on the total weight of the polycarbonate resin and the flame retardant made of a halogenated organic compound. The polycarbonate resin composition according to any one of the items.