JPH1060120A - Thermoplastic resin composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermoplastic resin compsn. which is less likely to cause decomposition of a phosphorous ester, i.e., has excellent thermal stability by mixing a thermoplastic resin with a phosphorous ester and a fatty ester in the substantial absence of a fatty acid. SOLUTION: A thermoplastic resin is mixed, particularly melt-kneaded, with a phosphorous ester as an antioxidant and a fatty ester as a release agent to prepare a molding in the substantial absence of a fatty acid in order to improve addition efficiency. Thus, a thermoplastic resin compsn. is prepd. The presence of both the phosphorous ester and the fatty ester is likely to reduce the effect of the antioxidant. This is generally attributable to hydrolysis of the phosphorous ester due to the presence of a fatty acid contained in a fatty ester, and the absence of the fatty acid can prevent the reduction in the effect of the antioxidant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermoplastic resin composition and a method for producing the same. More specifically,
The present invention relates to a method for producing a molded article in which the addition efficiency of an antioxidant and a release agent is improved when producing a thermoplastic resin composition to which a phosphite and a fatty acid ester are added.

[0002]

2. Description of the Related Art Injection molding method using thermoplastic resin as raw material,
In order to efficiently produce a desired molded product by heating and melting it by an extrusion molding method, a compression molding method, a calendar molding method, or the like, a high temperature is generally employed. However, if the heat melting temperature is increased, the resin may be colored yellow or brown due to thermal decomposition or thermal oxidation, etc.In order to prevent such coloring, various stabilizers such as antioxidants are used. Be blended.

Further, when a target molded article is produced by heating and melting a raw material thermoplastic resin, the flowability of the resin at the time of melting is improved, and the resin is easily released from a mold or a roll at the time of molding. Certain compounds are incorporated as release agents in order to eliminate roll contamination and molded article appearance defects. As the antioxidant, a phosphite compound or the like is used, and as the release agent, a fatty acid partial ester of glycerin or beeswax,
Whale oil is often used.

[0004] When a resin additive such as an antioxidant or a release agent is blended with a thermoplastic resin, the amount of the resin additive is generally very small relative to the raw material resin. When trying to mix a small amount of additive into the resin with a blender, tumbler, etc., the additive adheres to the inner wall surface of the blender, tumbler, etc., and the weighed amount is not blended with the resin as it is,
There is a disadvantage that the quality of the product varies. In order to eliminate such disadvantages, in advance, the raw material thermoplastic resin, a thermoplastic resin compatible with the raw material thermoplastic resin, or other inert powdery compound as a substrate, the additive content of A method of preparing a high master batch, dispersing the master batch in a thermoplastic resin as a raw material, and melt-kneading the master batch is adopted. Generally, a plurality of resin additives are blended into the raw material thermoplastic resin according to the use of the molded article, the molding conditions employed, and the like. When compounding a plurality of types of resin additives with the raw material resin, a method of forming a master batch in which a plurality of types of resin additives are simultaneously mixed is employed for the purpose of simplifying the operation.

[0005]

However, according to experiments by the present inventors, a masterbatch in which a phosphite and a fatty acid ester coexist (hereinafter sometimes referred to as a coexistence masterbatch) is used as a coexistence masterbatch. When a batch is prepared and used immediately thereafter, the expected additive effect is achieved.However, when a master batch that has been prepared and left for a long time is used, It was found that only a low addition effect was achieved. In particular, the effect of the antioxidant is greatly reduced over time in the coexisting masterbatch. In other words, it was found that the effect of adding the masterbatch to the thermoplastic resin as the raw material was greatly reduced in accordance with the period during which the coexisting masterbatch was left. An object of the present invention is to provide a method for improving the addition efficiency of these additives when mixing a phosphite ester and a fatty acid ester with a raw material thermoplastic resin, particularly when producing a molded article by melt-kneading. Is to do.

[0006]

According to the study of the present inventors, the above-mentioned decrease in the effect of the antioxidant is likely to be caused by the coexistence of the phosphite used and the fatty acid ester. It is due to the hydrolysis of the phosphite due to the presence of the fatty acid contained therein, and furthermore, this hydrolysis does not proceed in the presence of mere phosphite, but the presence of the fatty acid ester is degraded. Was found to promote.

That is, the gist of the present invention is to produce a thermoplastic resin composition in which a phosphite ester, a fatty acid ester and a thermoplastic resin are mixed with each other in a substantially absence of a fatty acid. Be in the way. Further, another gist of the present invention is to mix a phosphite, a fatty acid ester, and a thermoplastic resin, as a fatty acid ester,
The present invention resides in a method for producing a thermoplastic resin composition using substantially no fatty acid. Furthermore, another gist of the present invention is a thermoplastic resin composition containing a phosphite, a fatty acid ester, and a thermoplastic resin, wherein the fatty acid is 10 μmol / g or less based on the fatty acid ester. Exist in things.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the thermoplastic resin refers to a resin capable of producing a target molded product by an injection molding method, an extrusion molding method, a compression molding method, a calendar molding method, or the like. Specifically, polyamide resin, polycarbonate resin, modified polyphenylene oxide, polyester resin, general-purpose polystyrene, impact-resistant polystyrene, AS resin, ABS
Examples include styrene resins such as resins, olefin resins such as polyethylene and polypropylene, vinyl chloride resins, vinyl acetate resins, polyacetals, acrylic resins, and fluororesins. These resins may be used alone or as a mixture of two or more.

Among the above thermoplastic resins, polycarbonate resin, polyester resin, and polyamide resin are particularly effective. Polycarbonate resins include polymers or copolymers produced by (1) the phosgene method of reacting various dihydroxydiaryl compounds with phosgene, (2) the transesterification method of reacting dihydroxydiaryl compounds with diphenyl carbonate, and the like. Can be A typical example of a dihydroxydiaryl compound is bisphenol A.

As the polyester resin, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate,
Examples include polyhexamethylene terephthalate, polycyclohexamethylene terephthalate, and poly (ethylene terephthalate / ethylene isophthalate) copolymer.

Representative polyethylene terephthalate and polybutylene terephthalate among polyester resins are:
It can be produced by a condensation reaction using terephthalic acid and ethylene glycol or butylene glycol as raw materials. Examples of the polyamide resin include a lactam having three or more members, a polymerizable ω-amino acid, and a polyamide obtained by a polycondensation reaction of a dibasic acid and a diamine. Specifically, nylon-4, nylon-6, nylon-7, nylon-8, nylon-11, nylon-1
2, nylon 6.6, nylon 6.9, nylon
Aliphatic polyamides such as 6,10, nylon-6,12, nylon-6,6T and the like can be mentioned. In the present invention, a phosphite is used as an antioxidant or the like. Examples of the phosphite generally include compounds represented by the following general formula (I).

[0012]

Embedded image

In the formula (I), R ¹ , R ² and R ³
Represents a hydrogen atom, an alkyl group or an aryl group, respectively, and not all represent a hydrogen atom at the same time.リ ン 酸 The phosphite represented by the formula (I) is a monoester, diester or triester of phosphorous acid with an alcohol or phenol. The alkyl group as R ¹ , R ² and R ³ in the formula (I) includes a heptyl group, a hexyl group, an octyl group,
Ethylhexyl group, nonyl group, decyl group, dodecyl group,
Examples include an octadecyl group, a pentaerythrityl group, a cyclohexyl group, and the like, and examples of the aryl group include a phenyl group, a toluyl group, and a nonylphenyl group.

Specific examples of the phosphite represented by the formula (I) include tributyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, tristearyl phosphite, triphenyl phosphite and triphenyl phosphite. Cresyl phosphite, tris (nonylphenyl) phosphite, 2-ethylhexyl diphenyl phosphite, decyl diphenyl phosphite,
Examples thereof include phenyldi-2-ethylhexyl phosphite, phenyldidodecyl phosphite, tricyclohexyl phosphite, distearyl pentaerythrityl diphosphite, and diphenylpentaerythrityl diphosphite. Among them, a phosphite having at least one alkyl group is preferable. Such phosphites may be used alone or as a mixture of two or more.

In the present invention, a fatty acid ester is used as a release agent or the like. A release agent is a compound that improves the fluidity of the resin during melting, facilitates release from the mold or roll during molding, and has the function of eliminating stains on the mold or roll and poor appearance of the molded product. To tell. As the fatty acid ester, (1) an ester compound of a polyhydric aliphatic alcohol and a fatty acid having 10 to 22 carbon atoms, (2) whale oil, and (3) beeswax are preferably used. Two or more fatty acid esters may be used.

The polyhydric aliphatic alcohol used as a raw material of the compound (1) is a tri- to hexa-valent aliphatic alcohol, for example, glycerin, trimethylolpropane, pentaerythritol, mesoerythritol, pentitol, hexitol, sorbitol. And the like. Examples of the fatty acids having 10 to 22 carbon atoms include undecylic acid, lauric acid, dodecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachiic acid, and behenic acid. The carbon skeleton of these fatty acids may have a substituent such as a hydroxyl group.

The ester compound of the polyhydric aliphatic alcohol and the fatty acid is preferably a substantially partial ester compound. Among them, preferred is one in which 30% or more of the entire hydroxyl groups in the polyhydric alcohol remain unesterified. Specifically, glycerin monostearate, glycerin distearate, glycerin monobehenate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol monobehenate and the like can be mentioned. Such partial ester compounds may be used alone or as a mixture of two or more.

One of the features of the present invention is that, when mixing these thermoplastic resins, phosphites and fatty acid esters, the mixing is performed substantially in the absence of fatty acids. In conventional methods, free fatty acids are contained in the fatty acid esters, and as a result, the above mixing is performed in the presence of the fatty acids. In the present invention, mixing is performed in the absence of a fatty acid, for example, by using a fatty acid ester that does not substantially contain a fatty acid.
The fatty acid used herein is not particularly limited, but is a saturated or unsaturated fatty acid having 10 to 22 carbon atoms, or a mixture of both. For example, undecylic acid, lauric acid, dodecylic acid, myristic acid, pentadecylic acid , Palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachiic acid, behenic acid and the like. The carbon skeleton of these fatty acids may have a substituent such as a hydroxyl group. In general, fatty acids include fatty acids that can be generated by hydrolysis of the fatty acid ester used, but may include other fatty acids. For example, for stearic acid monoglyceride, palmitic acid is usually contained together with stearic acid. The amount of the fatty acid is 10 μmol / g or less based on the fatty acid ester,
Preferably it is 7 μmol / g or less. If the amount of fatty acid is too large, the decomposition of phosphorous acid tends to proceed. In order to reduce the fatty acids in the fatty acid ester, for example, a method such as extraction with an alkaline aqueous solution or separation with an ion exchange resin can be adopted.

Although the purpose of the above mixing may be any purpose, it is preferably used in the production of a co-existing masterbatch or in the mixing of a phosphite ester masterbatch and a fatty acid ester masterbatch. I do. A master batch of a phosphite or a fatty acid ester can be produced by the following procedure. A predetermined amount of a phosphite or a fatty acid ester is used as a base material based on (A) a starting thermoplastic resin, a thermoplastic resin compatible with the starting thermoplastic resin, or (B) another inert powdery compound. And it may be added to this.

In the case of the above (A), the ratio of the phosphite or fatty acid ester to the thermoplastic resin varies depending on the type of the resin and the like, but is 1/99 to 40/60 by the weight ratio of the master batch. You can choose from a range.
The method of mixing the above-mentioned two types of master batches with the raw material (for molding) resin is based on the appearance form of the raw material resin (powder, pellet, etc.), the appearance form of the two kinds of master batches, the method of manufacturing the desired molded product, and the like. Any of a dry blending method and a method of melt-kneading the dry-blended product can be used.

For example, when the raw material (for molding) resin is a powder and the molding method for producing a molded product is a melt-kneading type (extrusion molding, injection molding, calender molding, etc.), mixing by a dry blending method is preferable. However, they can be mixed by a melt kneading method. When mixing by a melt kneading method, it is preferable to use a kneader such as a single screw extruder, a twin screw extruder, a rotor type kneader or a Banbury mixer. In the case of a single-screw extruder, a screw with a dalmage type screw is preferable, and in the case of a twin-screw extruder, a coaxial twin screw type and a bidirectional twin screw type are preferable.

The amount of the phosphite to be added to the raw material (for molding) resin varies depending on the type of the resin, the molding method, the molding conditions, the type of the molded product, the use, and the like. It is better to select in the range of 0.5% by weight. If the amount is too small, it may be difficult to suppress coloration and transparency deterioration due to decomposition of the resin, whereas if it is too large, the decomposition of the antioxidant itself becomes conspicuous, and the surface of the molded product becomes conspicuous. Silver streaks are likely to occur. The phosphite is 0.01 to 0.2 in the above range.
% By weight is preferred.

The amount of the fatty acid ester relative to the raw material resin also varies depending on the type of resin, the molding method, the molding conditions, the type of molded product, the use, and the like.
It is preferable to select from the range of 0.5 to 1% by weight. If the amount is too small, the releasability and the effect of improving the appearance of the molded product may not be recognized, while if it is too large, gas generation during molding may increase, and molding stability may decrease. Fatty acid esters are preferably 0.01 to 0.5% by weight in the above range.

In addition to the above two components, various types of resin additives may be mixed with the raw material resin, depending on the use of the molded article, alone or in combination of two or more. As resin additives,
Plasticizers, lubricants, dyes, pigments, UV absorbers, weather resistance improvers, heat stabilizers, antistatic agents, flame retardants, glass fibers, carbon fibers, fibrous reinforcing materials such as potassium titanate whiskers, calcium carbonate, gypsum And fillers such as clay minerals.

[0025]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Reference Examples, Examples, and Comparative Examples, but the present invention is not limited to the following description examples without departing from the gist thereof. In addition, in the following description example, the analysis of the phosphite and the liberated fatty acid was measured according to the method described below.

(1) Analysis of Phosphite Ester A composition containing a phosphite is dissolved in methylene chloride, and this solution is directly measured by a gas chromatograph (manufactured by Shimadzu Corporation, Model GC-14A, FPD detector). It depends on how you do it. (2) Analysis of released fatty acid The partial ester compound containing the released fatty acid was dissolved in methylene chloride, and pyridine, chloroform and a silylating agent were added to this solution, and trimethylsilylation was performed at a temperature of 50 ° C. for 30 minutes. And the obtained solution was subjected to gas chromatography (model GC-7A, manufactured by Shimadzu Corporation, FI
D detector).

[Comparative Example 1] (Preparation of masterbatch to which antioxidant and release agent were added and measurement of change with time) 20 kg of polycarbonate (TM NOVAREX 7022PJ, manufactured by Mitsubishi Chemical Corporation) and tris (nonyl), an antioxidant 875 g of phenyl) phosphite (manufactured by Asahi Denka Kogyo Co., Ltd., TM Adeka Argus 329K) and a release agent stearic acid monoglyceride (manufactured by RIKEN Vitamin Co., Ltd.)
700 g of Riquemar S-100A) was dry-blended using a blender to obtain a master batch in which an antioxidant and a release agent coexist.

The obtained coexisting masterbatch is left at room temperature for a predetermined time (3 hours, 7 hours, 24 hours or 48 hours), and tris (nonylphenyl)
The residual amount of phosphite was analyzed. At this time, the amount of free fatty acids (stearic acid and palmitic acid) in the stearic acid monoglyceride was 20 μmol / g. Table 1 shows the measurement results.

[0029]

[Table 1] [Note] The values in Table 1 mean the residual ratio with respect to the amount of the added antioxidant.

Table 1 shows that the masterbatch in which the phosphite masterbatch and the fatty acid ester masterbatch coexist greatly reduces the residual ratio of the phosphite over time. Comparative Example 2 (Mixing of Antioxidant and Release Agent) Antioxidant Tris (nonylphenyl) phosphite (329 K same as Comparative Example 1) 1
g and 1.7 g of a release agent stearic acid monoglyceride (Likemar S-100A as in Comparative Example 1) were sufficiently mixed in a mortar to obtain a mixture of both additives. The prepared mixed sample was left at room temperature for a predetermined time (24 hours, 48 hours), and the residual ratio of tris (nonylphenyl) phosphite was measured according to the method described above.

As a result, the residual ratio was 95% after 24 hours, but decreased to 76% after 48 hours. From Comparative Examples 1 and 2, when both the phosphite and the fatty acid ester are mixed, the decrease in the residual ratio of the phosphite is apparent. The reason why the residual ratio of Comparative Example 1 was lower than that in this experiment is considered to be because the resin increased the surface area and contributed to the incorporation of moisture in the air. In addition, as a result of measuring the free fatty acids (stearic acid and palmitic acid) contained in the release agent stearic acid monoglyceride used in Comparative Example 2 according to the above-mentioned analysis method, 20
μmol / g.

Example 1 (Extraction of Free Fatty Acid in Release Agent) Release agent stearic acid monoglyceride (Likemar S-100 of the same type as Comparative Example 1)
A) 2 g of chloroform 320 ml, methanol 160
dissolved in a mixed solution of 0.01N NaOH
120 ml of the aqueous solution was added and mixed well. Let it stand 2
After separation into layers, the solvent in the lower layer was distilled off to obtain the desired product.
As a result of analysis according to the above-mentioned analysis method, the amount of free fatty acids (stearic acid, palmitic acid) in stearic acid monoglyceride was 6.5 μmol / g.

(Mixing of antioxidant and release agent subjected to alkali extraction) 1 g of antioxidant tris (nonylphenyl) phosphite (329 K of the same kind as in Comparative Example 1) and the release agent obtained in the above experiment 1.7 g of stearic acid monoglyceride was sufficiently mixed in a mortar to prepare a mixture of both additives. The prepared mixed sample was left at room temperature for a predetermined time (24 hours, 48 hours), and the residual ratio of tris (nonylphenyl) phosphite was measured according to the above-described analysis method. As a result, 24
After 100 hours, the residual ratio was 100%, and after 48 hours, the residual ratio was 100%. From the results of Comparative Example 2 and Example 1, it can be seen that the reduction of the free fatty acid is effective in suppressing the reduction of the phosphite.

[Comparative Example 3] (Mixing of a mold release agent with addition of stearic acid and an antioxidant) 1 g of antioxidant tris (nonylphenyl) phosphite (329 K same as in Comparative Example 1) and stearic acid (Ishizu Pharmaceutical Co., Ltd.) 1.7 g of a release agent stearic acid monoglyceride to which 240 μmol (special grade) was added (Likemar S- same as Comparative Example 1)
100A) was sufficiently mixed in a mortar, heated at 80 ° C. for 2 hours, and the residual ratio of tris (nonylphenyl) phosphite was measured according to the above-described analysis method. As a result, the survival rate was 6
6%.

Comparative Example 4 (Mixing with Release Agent and Antioxidant) Antioxidant tris (nonylphenyl) phosphite (329 K, same as Comparative Example 1)
1 g and 1.7 g of the release agent stearic acid monoglyceride (Likemar S-100A as in Comparative Example 1) were thoroughly mixed in a mortar, heated at 80 ° C. for 2 hours, and measured for the residual ratio of tris (nonylphenyl) phosphite as described above. It was measured according to the analysis method. As a result, the residual ratio was 85%. Comparative Examples 3 and 4 show that the addition of stearic acid promotes the decomposition of phosphite.

Reference Example 1 (mixture of antioxidant and stearic acid) Antioxidant tris (nonylphenyl) phosphite (same as Comparative Example 1
9K) 1 g and fatty acid (stearic acid as in Comparative Example 3) 2
After thoroughly mixing 40 μmol in a mortar, the mixture was heated at 80 ° C. for 2 hours, and the residual ratio of tris (nonylphenyl) phosphite was measured according to the above-described analysis method. As a result, the residual ratio was 98%. It can be seen from Reference Example 1 that the mixture of the phosphite and the fatty acid alone does not reduce the antioxidant. This is thought to be due to poor compatibility of both samples,
As a condition for the decomposition to occur, a substance that increases compatibility such as stearic acid monoglyceride is required.

[0037]

According to the present invention, it is possible to provide a thermoplastic resin composition having a low decomposition of phosphite, that is, excellent in thermal stability.

Claims (8)

[Claims] 1. A method for producing a thermoplastic resin composition, comprising mixing a phosphite, a fatty acid ester, and a thermoplastic resin in the absence of a fatty acid. 2. The method for producing a thermoplastic resin composition according to claim 1, wherein the mixing is performed in a system in which the fatty acid is 10 μmol / g or less based on the fatty acid ester. 3. A method for producing a thermoplastic resin composition, wherein a fatty acid ester containing substantially no fatty acid is used in mixing a phosphite ester, a fatty acid ester and a thermoplastic resin. 4. The method for producing a thermoplastic resin composition according to claim 3, wherein a fatty acid ester having a fatty acid content of 10 μmol / g or less based on the fatty acid ester is used. 5. The method for producing a thermoplastic resin composition according to claim 1, wherein the fatty acid is a fatty acid having 1 to 22 carbon atoms. 6. The fatty acid ester is at least one selected from (1) an ester compound of a polyhydric aliphatic alcohol and a fatty acid having 10 to 22 carbon atoms, (2) whale oil and (3) beeswax. 6. The method for producing the thermoplastic resin composition according to any one of items 5 to 5. 7. The method for producing a thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is at least one selected from a polycarbonate resin, a polyester resin, and a polyamide resin. 8. A thermoplastic resin composition comprising a phosphite ester, a fatty acid ester and a thermoplastic resin, wherein the fatty acid is 10 μmol / g or less based on the fatty acid ester.