JP3440708B2 - Thermoplastic resin composition and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic resin composition and a method for producing the same. More specifically, in particular,
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 ester and a fatty acid ester are added.

[0002]

2. Description of the Related Art An injection molding method using a thermoplastic resin as a raw material,
A high temperature is generally used when an objective molded article is efficiently produced by heating and melting by an extrusion molding method, a compression molding method, a calender molding method, or the like. However, when the heating and melting temperature is increased, the resin may be colored yellow or brown due to thermal decomposition or thermal oxidation.Therefore, various stabilizers such as antioxidants are used for the purpose of preventing such coloring. Be compounded.

Further, when a raw material thermoplastic resin is heated and melted to produce a desired molded article, the fluidity of the resin at the time of melting is improved so that it can be easily released from a mold or roll at the time of molding. In order to eliminate stains on the roll and poor appearance of the molded product, a certain compound is compounded as a release agent. As the antioxidant, a phosphite ester 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.

When the thermoplastic resin is blended with a resin additive such as an antioxidant or a release agent, the amount of the resin additive is generally a very small amount relative to the raw material resin. If you try to mix a small amount of additive into the resin with a blender, tumbler, etc., the additive will adhere to the inner wall surface of the blender, tumbler, etc., and the measured amount will not be blended into the resin as it is,
There is a drawback that the quality of the product varies. In order to eliminate such drawbacks, the raw material thermoplastic resin, the thermoplastic resin compatible with the raw material thermoplastic resin, or other inert powdery compound is used as a base material in advance of the additive content. A method in which a high masterbatch is prepared in advance, and this masterbatch is dispersed in a thermoplastic resin as a raw material and melt-kneaded is adopted. It is usual that a plurality of resin additives are blended with the raw material thermoplastic resin depending on the use of the molded product, the molding conditions adopted, and the like. When a plurality of types of resin additives are blended with the raw material resin, a method of forming a masterbatch in which a plurality of types of resin additives are blended at the same time is adopted for the purpose of simplifying the work.

[0005]

However, according to the experiments conducted by the present inventors, a masterbatch in which a phosphite ester and a fatty acid ester coexist (hereinafter sometimes referred to as a coexistence masterbatch) is a coexistence master. When a batch is prepared and used immediately after that, the expected additive additive effect is achieved, but when using a masterbatch that has been left for a long time after preparation, it is more than expected. It was found that only low addition effects were achieved. In particular, the effect of the antioxidant greatly decreases with time in the coexistence masterbatch. In other words, it was found that the effect of adding the masterbatch to the raw material thermoplastic resin is significantly reduced in accordance with the standing period of the coexisting masterbatch. An object of the present invention is to provide a method for improving the addition efficiency of these additives when a raw material thermoplastic resin is mixed with a phosphite ester and a fatty acid ester, particularly when a molded article is produced by melt kneading. To do.

[0006]

According to the studies by the present inventors, the reduction of the effect of the above-mentioned antioxidant is likely to occur due to the coexistence of the phosphite ester and the fatty acid ester used, and it is usually the fatty acid ester. It is due to the hydrolysis of the phosphite ester due to the presence of the fatty acid contained therein, and further, this hydrolysis does not proceed in the coexistence with mere phosphite ester, but the presence of the fatty acid ester is decomposed. Was found to promote.

That is, the gist of the present invention is to produce a thermoplastic resin composition in which the phosphite ester, the fatty acid ester and the thermoplastic resin are mixed in the substantial absence of fatty acid. In the way. In addition, another gist of the present invention is to mix a phosphite ester, 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 that uses a substance that does not substantially contain a fatty acid. Still another subject matter of the present invention is a thermoplastic resin composition containing a phosphite ester, a fatty acid ester, and a thermoplastic resin, wherein the fatty acid ester is 10 μmol / g or less with respect to the fatty acid ester. It exists in things.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, the thermoplastic resin means a resin capable of producing a target molded article by an injection molding method, an extrusion molding method, a compression molding method, a calender molding method or the like. Specifically, polyamide resin, polycarbonate resin, modified polyphenylene oxide, polyester resin, general-purpose polystyrene, high-impact polystyrene, AS resin, ABS
Examples thereof 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 kinds.

Among the above-mentioned thermoplastic resins, the effect is particularly remarkable in the polycarbonate resin, polyester resin and polyamide resin. Examples of the polycarbonate resin include polymers or copolymers produced by (1) a phosgene method of reacting various dihydroxydiaryl compounds with phosgene, (2) a transesterification method of reacting a dihydroxydiaryl compound with diphenylcarbonate, or the like. To be A typical example of the dihydroxydiaryl compound is bisphenol A.

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

Among the polyester resins, typical polyethylene terephthalate and polybutylene terephthalate 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, phosphite is used as an antioxidant and the like. As the phosphite ester, a compound represented by the following general formula (I) can be usually mentioned.

[0012]

[Chemical 1]

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

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-ethylhexyldiphenylphosphite, decyldiphenylphosphite,
Examples thereof include phenyldi-2-ethylhexyl phosphite, phenyldidodecyl phosphite, tricyclohexyl phosphite, distearyl pentaerythrityl diphosphite, and diphenylpentaerythrityl diphosphite. Among them, phosphite having at least one alkyl group is preferable. Such phosphite may be used alone or as a mixture of two or more kinds.

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

The polyhydric aliphatic alcohol used as the raw material of the compound (1) is a trivalent to hexavalent aliphatic alcohol such as glycerin, trimethylolpropane, pentaerythritol, mesoerythritol, pentitol, hexitol and sorbitol. And so on. Examples of the fatty acid having 10 to 22 carbon atoms include undecyl acid, lauric acid, dodecyl acid, myristic acid, pentadecylic acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic 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 above polyhydric aliphatic alcohol and the above fatty acid is preferably a substantially partial ester compound. Among them, those in which 30% or more of all the hydroxyl groups in the polyhydric alcohol are left unesterified are preferred. Specific examples include glycerin monostearate, glycerin distearate, glycerin monobehenate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol monobehenate and the like. Such partial ester compounds may be used alone or as a mixture of two or more kinds.

One of the features of the present invention is that when these thermoplastic resin, phosphite ester and fatty acid ester are mixed, the mixing is carried out in the substantial absence of fatty acid. In the conventional method, free fatty acid was contained in the fatty acid ester, and as a result, the above mixing was performed in the presence of fatty acid. In the present invention, the mixing is performed in the absence of fatty acids, such as by using fatty acid esters that do not substantially contain fatty acids.
The fatty acid referred to here is not particularly limited, but is a saturated fatty acid having 10 to 22 carbon atoms or an unsaturated fatty acid, or a mixture of both, and examples thereof include undecyl acid, lauric acid, dodecyl acid, myristic acid, and pentadecyl acid. , Palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid and the like. The carbon skeleton of these fatty acids may have a substituent such as a hydroxyl group. Generally, the fatty acid includes a fatty acid that can be produced 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 fatty acid is 10 μmol / g or less based on the fatty acid ester,
It is preferably 7 μmol / g or less. When the amount of fatty acid is too large, the decomposition of phosphorous acid tends to proceed. In order to reduce the fatty acid 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.

The purpose of the above mixing may be any, but it is preferably used in the production of a coexistence masterbatch or in the mixing of a phosphite ester masterbatch and a fatty acid ester masterbatch. To do. The master batch of phosphite ester or fatty acid ester can be manufactured by the following procedures. A predetermined amount of phosphite ester or fatty acid ester is used as the base material of (A) a raw material thermoplastic resin, a thermoplastic resin compatible with the raw material thermoplastic resin, or (B) another inert powdery compound. And may be added to this.

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

For example, when the raw material (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. In the case of mixing by the melt-kneading method, it is preferable to use a kneader such as a single-screw extruder, a twin-screw extruder, a rotor-type kneader, a Banbury mixer. In the case of a single-screw extruder, a dullage type screw is preferable, and in the case of a twin-screw extruder, a same-direction twin-screw type and a different-direction twin-screw type are preferable.

The compounding amount of the phosphite ester with respect to the raw material (for molding) resin varies depending on the type of resin, the molding method, the molding conditions, the type of molded product, the application, etc. It is preferable to select in the range of 0.5% by weight. If this amount is too small, it may be difficult to suppress coloration due to resin decomposition and deterioration of transparency. Conversely, if it is too large, decomposition of the antioxidant itself becomes conspicuous, and the molded product surface It is easy for silver streaks to occur. The phosphite is 0.01 to 0.2 in the above range.
Weight percent is preferred.

The amount of the fatty acid ester compounded with respect 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, etc., but is 0.0 with respect to the raw material resin.
It is preferable to select in the range of 05 to 1% by weight. If this amount is too small, the releasability and appearance improving effect of the molded product may not be recognized, and conversely, if it is too large, gas generation during molding may increase and molding stability may decrease. The fatty acid ester is preferably 0.01 to 0.5% by weight within the above range.

In addition to the above-mentioned two components, various kinds of resin additives may be blended in the raw material resin in one kind or in a combination of two or more kinds depending on the use of the molded product. As a resin additive,
Plasticizer, lubricant, dye, pigment, ultraviolet absorber, weather resistance improver, heat stabilizer, antistatic agent, flame retardant, glass fiber, carbon fiber, fibrous reinforcing material such as potassium titanate whiskers, calcium carbonate, gypsum. , And fillers such as clay minerals.

[0025]

EXAMPLES The present invention will be described below in detail with reference to reference examples, examples and comparative examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, in the following description example, the analysis of the phosphite ester and the liberated fatty acid was measured according to the method described below.

(1) Analysis of phosphite ester A composition containing phosphite ester was dissolved in methylene chloride, and this solution was 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 free fatty acid A partial ester compound containing a free fatty acid is dissolved in methylene chloride, pyridine, chloroform and a silylating agent are added to this solution, and trimethylsilylation is performed at a temperature of 50 ° C for 30 minutes to room temperature. The obtained solution was cooled to a gas chromatograph (manufactured by Shimadzu Corporation, model GC-7A, FI).
D detector).

Comparative Example 1 (Preparation of Masterbatch with Antioxidant and Release Agent Added and Measurement of Change with Time) 20 kg of polycarbonate (TM Novarex 7022PJ, manufactured by Mitsubishi Chemical Co.) and tris (nonyl) antioxidant Phenyl) phosphite (manufactured by Asahi Denka Co., Ltd., TM ADEKA ARGUS 329K) and 875 g of a release agent stearic acid monoglyceride (manufactured by Riken Vitamin Co.,
Riquemar S-100A) (700 g) was weighed, and both were dry blended with a blender to obtain a coexistence masterbatch of an antioxidant and a release agent.

The coexisting masterbatch thus obtained was allowed to stand at room temperature for a predetermined time (3 hours, 7 hours, 24 hours or 48 hours), and tris (nonylphenyl) was prepared according to the above-mentioned analysis method.
The remaining amount of phosphite was analyzed. The amount of free fatty acids (stearic acid, palmitic acid) in the stearic acid monoglyceride at this time was 20 μmol / g. The measurement results are shown in Table 1.

[0029]

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

From Table 1, it can be seen that in the masterbatch in which the phosphite ester masterbatch and the fatty acid ester masterbatch coexist, the residual rate of the phosphite ester significantly decreases with the passage of time. Comparative Example 2 (Mixture of Antioxidant and Release Agent) Antioxidant Tris (nonylphenyl) phosphite (same as Comparative Example 1 329K) 1
g and 1.7 g of the release agent stearic acid monoglyceride (the same Riquemar S-100A as in Comparative Example 1) were thoroughly 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 rate of tris (nonylphenyl) phosphite was measured according to the method described above.

As a result, after 24 hours, the residual rate was 95%, but after 48 hours, the residual rate had dropped to 76%. From Comparative Examples 1 and 2, it is clear that when both the phosphite ester and the fatty acid ester are mixed, the residual rate of the phosphite ester is reduced. The reason why the residual rate of Comparative Example 1 is lower than that of the present experiment is considered that the resin increased the surface area and contributed to the uptake of water in the air. The free fatty acid (stearic acid, palmitic acid) contained in the release agent stearic acid monoglyceride used in Comparative Example 2 was measured according to the above-mentioned analysis method, and as a result, 20
It was μmol / g.

[Example 1] (Extraction of free fatty acid in release agent) Release agent stearic acid monoglyceride (the same kind of LIKEMAR S-100 as in Comparative Example 1)
A) 2 g of chloroform 320 ml, methanol 160
Dissolve in a mixed solution of 0.01 ml and add 0.01 N NaOH.
120 ml of the aqueous solution was added and mixed well. Let stand 2
After separating the 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 acid (stearic acid, palmitic acid) in stearic acid monoglyceride was 6.5 μmol / g.

(Mixture of Antioxidant and Alkali-Extracted Release Agent) 1 g of antioxidant tris (nonylphenyl) phosphite (329 K, which is 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 thoroughly 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 rate of tris (nonylphenyl) phosphite was measured according to the above-described analysis method. As a result, 24
After the lapse of time, the remaining rate was 100%, and even after 48 hours, the remaining rate was 100%. From the results of Comparative Example 2 and Example 1, it can be seen that the reduction of free fatty acid is effective in suppressing the reduction of phosphite.

Comparative Example 3 (Mixing of Release Agent with Stearic Acid and Antioxidant) 1 g of antioxidant tris (nonylphenyl) phosphite (329K same as in Comparative Example 1) and stearic acid (Ishizu Pharmaceutical Co., Ltd.) Mold release agent stearic acid monoglyceride added with 240 μmol of special grade 1.7 g (the same kind of Rikemar S- as Comparative Example 1)
100 A) was thoroughly mixed in a mortar and then heated at 80 ° C. for 2 hours, and the residual rate of tris (nonylphenyl) phosphite was measured according to the above-described analysis method. As a result, the survival rate is 6
It was 6%.

[Comparative Example 4] (Mixing with mold release agent and antioxidant) Antioxidant tris (nonylphenyl) phosphite (same as Comparative Example 1 329K)
After thoroughly mixing 1 g of the release agent with 1.7 g of stearic acid monoglyceride (the same Liquemal S-100A as in Comparative Example 1) in a mortar, the mixture was heated at 80 ° C. for 2 hours, and the residual rate of tris (nonylphenyl) phosphite was measured as described above. It was measured according to the analysis method. As a result, the residual rate was 85%. From Comparative Examples 3 and 4, it can be seen 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 32
9K) 1 g and fatty acid (the same stearic acid as 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 rate of tris (nonylphenyl) phosphite was measured according to the above-mentioned analysis method. As a result, the residual rate was 98%. It can be seen from Reference Example 1 that the antioxidant does not decrease only by mixing the phosphite and the fatty acid. This is thought to be due to the poor compatibility of both samples,
As a condition under which decomposition occurs, a substance that enhances compatibility such as stearic acid monoglyceride is required.

[0037]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-127661 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 3/20-3/215 C08L 1 / 00-101/16

Claims (8)

(57) [Claims] 1. A method for producing a thermoplastic resin composition, which comprises mixing a phosphite ester, a fatty acid ester and a thermoplastic resin in the substantially absence of 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 with respect to the fatty acid ester. 3. A method for producing a thermoplastic resin composition, wherein a fatty acid ester that does not substantially contain a fatty acid is used in mixing the phosphite ester, the fatty acid ester, and the thermoplastic resin. 4. The method for producing a thermoplastic resin composition according to claim 3, wherein a fatty acid ester having a fatty acid 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) polyhydric aliphatic alcohol and ester compounds of fatty acids having 10 to 22 carbon atoms, (2) whale oil and (3) beeswax. 6. A method for producing the thermoplastic resin composition according to any one of items 1 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 containing 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.