JPS6210540B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to stabilized colored polycarbonate resin compositions. More specifically, the present invention relates to a stabilized colored polycarbonate resin composition comprising a polycarbonate resin mixed with a pigment and an organic phosphonic acid ester. Polycarbonate resins are widely used as engineering plastics because they have high impact resistance, transparency, heat resistance, electrical properties, dimensional stability, etc. Depending on its commercial use, it is necessary to add pigments to the polycarbonate resin to improve its appearance, but the commercial value of colored molded products is determined by their hue and clarity. Furthermore, titanium dioxide, which has excellent hiding power, is often used as a pigment. However, since pigments such as titanium dioxide promote the oxidative decomposition of polycarbonate resins, polycarbonate resins colored with pigments have a lower degree of discoloration and molecular weight reduction during the molding process than polycarbonate resins that do not contain pigments. It has the disadvantage of becoming larger and may not produce the expected hue or intensity. Organic phosphite esters such as triaryl phosphites and trialkyl phosphites have traditionally been used to prevent discoloration and molecular weight reduction during the molding process of polycarbonate resins, but these stabilizers are Although it acts effectively on resins, it does not show a sufficient stabilizing effect when pigments are included. Therefore, the use of phosphoric acid mono- or diesters as heat stabilizers for polycarbonate resins containing pigments has been proposed, but these stabilizers must also be used under strict conditions of 300°C or higher to accommodate the thinning of molded products in line with resource conservation. During molding at the bottom, there is a large discoloration and a large drop in molecular weight. An object of the present invention is to provide a colored polycarbonate resin composition with excellent thermal stability that does not cause deterioration or discoloration during the molding process at high temperatures. As a result of intensive research to achieve this objective, the present inventors have found that a colored polycarbonate resin composition prepared by adding and mixing a pigment and a specific organic phosphonic acid ester to a polycarbonate resin maintains a stable hue and molecular weight during high-temperature molding. They discovered this and arrived at the present invention. That is, the present invention provides polycarbonate resin with
Pigments and general formula (1) (However, R ₁ , R ₂ and R ₃ in the formula are each an alkyl group having 1 to 18 carbon atoms, and n is 1 or 2
This is a stabilized colored polycarbonate resin composition characterized by containing an organic phosphonic acid ester represented by The stabilized colored polycarbonate resin composition of the present invention does not cause discoloration or deterioration of mechanical properties due to molecular weight reduction during the molding process at high temperatures.
It can be easily molded into a thin-walled molded product at high temperatures, and a large amount of pigment can be added to the molded product to hide the thinning of the wall and to maintain the hue. The excellent effects of such a composition were first achieved by blending a pigment and a specific organic phosphonic acid ester with a polycarbonate resin. This is surprising considering that dioctyl phosphonate has no effect on preventing molecular weight reduction. Judging from the fact that the farther the ester bond is from the phosphorus atom, the smaller the effect, it is thought that the interaction between the ester bond and the phosphorus atom plays an important role in the stabilizing effect of the organic phosphonic acid ester used in the present invention. However, its mechanism of action is not clear. The polycarbonate resin used in the present invention is produced by the reaction of divalent phenol with a carbonate precursor such as phosgene in the presence of an acid acceptor and a molecular weight regulator, or the ester reaction of divalent phenol with a carbonate precursor such as diphenyl carbonate. Produced by exchange reaction. The divalent phenol that can be used here is preferably bisphenols, and 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) is particularly preferable. Further, part or all of bisphenol A may be replaced with another divalent phenol. Examples of divalent phenols other than bisphenol A include hydroquinone, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)alkane, bis(4-hydroxyphenyl)cycloalkane, and bis(4-hydroxyphenyl). ) sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxydiphenyl) sulfoxide, bis(4-hydroxyphenyl) ether or bis(3,5-dibromo-4-hydroxyphenyl) These are halogenated bisphenols such as propane. It may be a homopolymer of these dihydric phenols, a copolymer of two or more types, or a blend thereof. The pigments used in the present invention are described in, for example, "Practical Handbook of Additives for Plastics and Rubber" edited by Kanbara and Imoto.
These are compounds categorized in pages 791 to 797 (published by Kagaku Kogyosha), and more specific examples include metal oxides such as titanium dioxide and zinc oxide, cadmium yellow, ultramarine, and carbon black. ,
It is not necessarily limited to these. These pigments may be used alone or together with other pigments or dyes. Among these pigments, titanium dioxide is preferred. The organic phosphonic acid ester used in the present invention has the general formula (1) , n is 1 or 2, and the alkyl groups of R ₁ , R ₂ and R ₃ have 18 carbon atoms.
They are as follows, preferably those in which the alkyl group has 8 or less carbon atoms, and more preferably those in which the alkyl group has 2 carbon atoms. Specific examples of such organic phosphonic acid esters include methyldimethylphosphonoacetate, methyldimethylphosphonopropionate, butyldibutylphosphonoacetate, butyldibutylphosphonopropionate, octyldioctylphosphonoacetate,
Examples include octyldioctylphosphonopropionate, and ethyldiethylphosphonoacetate and ethyldiethylphosphonopropionate are particularly preferably used. The blending ratio of each component of the composition in the present invention is as follows: 100 parts by weight of polycarbonate resin, pigment:
0.001 to 5 parts by weight, organic phosphonic acid ester
0.001 to 0.2 parts by weight is preferred. Preparation of the colored polycarbonate resin compositions of the present invention may be carried out by any conventional method. For example, a method of directly adding a pigment and an organic phosphonic acid ester to a polycarbonate resin;
Added high concentration of pigment and organic phosphonic acid ester,
A method of producing a so-called blended master batch and blending it with other polycarbonate resin to achieve a predetermined additive concentration; Alternatively, after adding an organic phosphonate ester to a methylene chloride solution or powder of a polycarbonate resin in advance, pigment There are methods such as adding . The composition of the present invention may contain other stabilizers such as organic phosphites, additives for the purpose of modifying the polycarbonate resin, reinforcing agents such as glass fiber, antioxidants, retardant agents, and light stabilizers. Agents, plasticizers, fillers, antistatic agents, mold release agents, lubricants, foaming agents, etc. can be added. Further, other resins such as polyethylene, polypropylene, polystyrene, polymethyl methacrylate, AS resin, ABS resin, and polyphenylene oxide may be mixed with the polycarbonate resin. The present invention will be explained below using examples. Note that parts in the examples indicate parts by weight. In addition, thermal stability was evaluated by the following method. Thermal stability evaluation method: Pellets were molded using an injection molding machine at a molding temperature of 340°C.
70mm x 50mm after staying at ℃ for 0 or 10 minutes
It was molded into a 2 mm sample plate. The L, a, and b values of the obtained sample board were measured by Hunter using a color difference meter (Suga Test Instruments).
Co., Ltd.), and the hue was evaluated by the b value. The smaller the b value, the less yellow and the better the hue. The degree of discoloration is ΔE=√(−′) ² +(−
a') ² + (b-b') ² (Here, L, a, b are the measured values of the molded sample plate at 340℃ residence time 0 minutes, L', a', b' are 340
These are the measured values of a molded sample plate kept at ℃ for 10 minutes. ) was evaluated. The smaller ΔE is, the smaller the discoloration is and the better it is. In addition, the molecular weight of the sample plate was measured by a viscosity method to evaluate the decrease in molecular weight. Examples 1 to 4 and Comparative Examples 1 to 3 Molecular weight 24500 prepared by reaction of 2,2-bis(4-hydroxyphenyl)propane and phosgene
To 100 parts of polycarbonate resin, 0.5 part of titanium dioxide (R-930 manufactured by Ishihara Sangyo Co., Ltd.) and the parts shown in Table 1 of organic phosphonic acid ester or tris(nonylphenyl) phosphite were added, and each was mixed using a super mixer. After mixing thoroughly,
It was extruded into pellets using a 30 mmφ extruder. The obtained pellets were injection molded by the method described above, and their thermal stability was evaluated. The results are shown in Table 1.

Table 1 shows that the composition of the present invention maintains stable hue and molecular weight and has excellent thermal stability.

Claims (1)

[Claims] 1 Polycarbonate resin, pigment and the following general formula (1) (However, R ₁ , R ₂ and R ₃ in the formula are each an alkyl group having 1 to 18 carbon atoms, and n is 1 or 2
A stabilized colored polycarbonate resin composition containing an organic phosphonic acid ester represented by 2. The composition according to claim 1, wherein the pigment is titanium dioxide. 3 The organic phosphonic acid ester has the following general formula (2) (However, n in the formula is 1 or 2.) The composition according to claim 1, wherein the composition is a compound represented by the following formula.