JPH089686B2 - Mold deposit prevention color masterbatch resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is produced in a mold at the time of molding such as injection molding and cast molding by mixing and mixing a mold deposit preventing colored masterbatch resin composition with a polyacetal resin. The present invention relates to a colored masterbatch resin composition in which the formation of deposits, so-called mold deposits is significantly suppressed and the productivity of molded products is improved.

[Prior Art] In recent years, polyacetal resins have been widely used in many fields such as electric parts, office equipment parts, and building materials because they have excellent strength characteristics, fatigue characteristics, and electric characteristics. It is increasing.

In addition, it is widely used for appearance purposes, and polyacetal resins colored with a colorant have various demands as in general colorless polyacetal resins.

As a conventional method for producing a colored polyacetal resin, a method for producing a colored polyacetal resin by adding a colorant to a polyacetal resin powder or a beret and kneading with an extruder, and preliminarily blending a large amount of a colorant with a thermoplastic resin. A high-concentration colored polyacetal resin masterbatch is prepared with an extruder, a kneading mixer, etc., and the colored masterbatch is roughly mixed into a polyacetal resin, uniformly blended, and injection-molded or extruded to obtain a desired colored product. Has been adopted.

This colored polyacetal resin is usually molded into a desired shape by injection molding, but at this time, a so-called mold deposit is generated on the surface of the mold, which is transferred to the surface of the molded product, resulting in a markedly deteriorated appearance of the molded product. However, there is a drawback that it is difficult to use as a component material such as a gear that requires high dimensional accuracy. To minimize such troubles,
The mold used for molding the polyacetal resin has to be disassembled and cleaned every time it is used, but this requires a great deal of time, which inevitably reduces productivity.

By the way, it has been proposed to mix a polyamide resin for the purpose of improving the thermal stability of the polyacetal resin (JP-A-34-5440), but in this case, heat and oxygen are not stored in the cylinder of the molding machine. Under the action of, there is a problem that the color changes to yellowish brown, and blackish brown charring adheres to the screw. Further, it has been carried out to blend a boric acid ester of monoacyl glycerin for the purpose of imparting an antistatic effect without impairing the thermal stability of the polyacetal resin (Japanese Patent Publication No. 57-15616), but these additions have been made. The colored polyacetal resin obtained by adding the above substances alone was not always satisfactory in terms of preventing mold deposit.

[Problems to be Solved by the Invention] The present invention significantly suppresses mold deposits generated in a mold in molding of a colored polyacetal resin using a mold such as injection molding and cast molding, and improves quality of a molded product. The present invention has been made for the purpose of providing a colored masterbatch resin composition for polyacetal resin, which is capable of improving productivity and has excellent thermal stability.

[Means for Solving the Problems] The inventors of the present invention have conducted intensive studies to prevent the generation of mold deposits that adhere to the inside of a mold when a colored polyacetal resin is molded using a colored masterbatch resin composition. As a result, from 100 parts by weight of the thermoplastic resin, 0.001 × D parts by weight to 0.5 × D parts by weight of the polyamide resin, and 0.01 × D parts by weight of boric acid ester of monoacyl glycerin to 5 parts by weight.
The inventors have found that a colored masterbatch resin composition containing xD parts by weight and a colorant (pigment) in an arbitrary ratio can achieve the object, and completed the present invention. D here means the dilution ratio of the masterbatch, and the dilution ratio means the ratio of the colored masterbatch resin composition to the uncolored polyacetal resin, for example, 20 times dilution means the colored masterbatch: polyacetal resin = It means 1:19 (weight ratio). D is preferably 2 to 100 times.

The thermoplastic resin used as the component (A) in the composition of the present invention includes, for example, oriacetal resin, polyester resin, polyamide resin, polycarbonate resin, polyolefin resin, polyphenylene oxide resin, polystyrene resin, ABS resin, AS resin, acrylic resin. Etc., which may be used alone or in combination, but a polyacetal resin alone is particularly preferable.

The polyamide resin used as the component (B) in the composition of the present invention is a linear polymer compound having an acid amide bond —CONH—, and is usually a condensation of a diamine and a dicarboxylic acid, a condensation of an amino acid, and a lactam opening. It is obtained by ring polymerization or the like. Examples of the polyamide resin include nylon 6, nylon 6.6, nylon 6/6/6, nylon 6
/ 6/10, Nylon 6.6 / 6/10, Nairo 610, Nylon 6/6/6/6/10, Nylon 12 and so on. Among these polyamide resins, nylon 6.6, Nylon 6 /
6/6, nylon 6/6/6/10, nylon 6/6/6/6/10 are suitable.

These polyamide resins may be used alone or in combination of two or more, and the amount thereof is 0.001 × D to 100 parts by weight of the thermoplastic resin (A).
It is necessary to select 0.5 × D parts by weight, preferably 0.05 × D to 0.5 × D parts by weight. If this amount is less than 0.001 × D parts by weight, the effect of preventing mold deposit is not sufficiently exerted, and if it exceeds 0.5 × D parts by weight, it will turn brown in color due to the action of heat and oxygen in the molding machine cylinder over time. , The screw may have a dark brown charring.

Examples of the boric acid ester of monoacylglycerin as the component (C) in the composition of the present invention are obtained by reacting a monoester of a fatty acid having 8 to 22 carbon atoms with glycerin and boric acid. (Wherein R ³ is an alkyl group or an alkenyl group having 7 to 21 carbon atoms, and m is 1 or 2) is used as a main component. Specific examples of the fatty acid include cabrinic acid, lauric acid, myristic acid, stearic acid, linoleic acid, oleic acid, and behenic acid. This borate ester may be either a monoester or a diester.

The boric acid ester of monoacyl glycerol as the component (C) may be used alone or in combination of two or more kinds. It is necessary to select the compounding amount within the range of 0.01 × D to 5 × D parts by weight, preferably 0.01 × D to 3 × D parts by weight, per 100 parts by weight of the component (A) polyatar resin. If this amount is less than 0.01 × D parts by weight, the effect of preventing mold deposit due to the synergistic effect with the polyamide resin is not sufficiently exhibited, and if it exceeds 5 × D parts by weight, the polyacetal resin is likely to be thermally decomposed.

Further, the colorant includes generally-known organic pigments and inorganic pigments, and also includes treated pigments having dispersibility, heat resistance, weather resistance and the like.

Further, the amount of the colorant added is not particularly limited, depending on the dilution ratio.

The polyacetal resin may be a polyacetal homopolymer or a polyacetal copolymer. The polyacetal homopolymer is composed of repeating oxymethylene units CH ₂ O, and can be produced by homopolymerizing formaldehyde or trioxane.

On the other hand, the polyacetal copolymer has a general formula of oxymethylene units in the chain. (R ¹ and R ² in the formula are each a hydrogen atom, an alkyl group or an aryl group, and adjacent R ^{1 s} , adjacent R ^{2 s} , and R ¹ and R ^{2 s} may be the same. , And n is an integer of 2 to 6), and has a structure in which oxyalkylene units represented by are randomly introduced.

The content of the oxyalkylene unit in this copolymer is 0.05 to 50 with respect to 100 mol of the oxymethylene unit.
Desirably, it is in the range of 0.1 to 20 moles, preferably 0.1 to 20 moles. Examples of the oxyalkylene unit include an oxyethylene unit, an oxypropylene unit, an oxytrimethylene unit, an oxytetramethylene unit, an oxybutylene unit and an oxyphenylethylene unit. Among these oxyalkylene units, from the viewpoint of improving the physical properties of the polyacetal resin composition, oxyethylene units (CH ₂ ) ₂ O and oxytetramethylene units (C
H ₂ ) ₄ O is particularly preferred.

The polyacetal copolymer can be produced, for example, by copolymerizing at least one selected from formaldehyde, trioxane and polyoxymethylene with a cyclic ether.

As a criterion for the mold deposit prevention ability, the resin composition of the present invention may be blended in a polyacetal resin at an arbitrary ratio and uniformly blended to perform continuous molding. The thermal decomposition volatile content of the molded piece after blending is usually 1500 ppm or less.

The masterbatch resin composition of the present invention optionally decomposes against other heat stabilizers, such as amide compounds, urea derivatives, polysaccharides, cellulose, etc., or polyacetal resin, within a range that does not impair the object of the present invention. An antioxidant, a light stabilizer, a lubricant or the like having a low action may be added, or a low molecular weight polymer such as a polyolefin wax may be added as a dispersibility improving agent for the colorant.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

The properties of the colored polyacetal resin composition prepared by blending the colored masterbatch resin composition and the polyacetal resin were determined according to the following methods.

(1) Mold deposit (MD) and occurrence of charring Using an injection molding machine, a cylinder temperature of 200 ° C and a mold temperature of 70 ° C are used to continuously injection-mold a molded product having a length of 75 mm, a width of 14 mm, and a thickness of 2 mm. In the operation, using a pin gate mold (without degassing), determine the number of moldings until the surface of the molded product begins to lose gloss due to MD generation and the number of days until a slight scorching occurs on the screw surface of the molding machine and evaluate. did.

(2) Generation of Silver Streak The composition was retained at a cylinder temperature of 230 ° C using an injection molding machine, and the critical retention time at which silver streak was generated in the molded product due to decomposed formaldehyde gas was determined and evaluated.

(3) Pyrolytic volatile content 10 g of sample (molded piece) was put into a cylindrical stainless steel container with an inner diameter of 50 mm and a depth of 50 mm, a stainless steel lid was placed on the top, and it was sealed at 200 ° C silicone. After 180 minutes of immersion in an oil bath, determine the amount of volatile matter adhering to the stainless steel upper lid, and then determine the amount of volatile matter by thermal decomposition [ppm (w / w
w)].

It should be noted that cooling water at 25 ° C. is passed through the upper lid so that volatile matter may easily adhere to the upper lid.

Examples 1-10, Comparative Examples 1-6 Polyacetal resin copolymer [MI = 9.0 g / 10 min (190
℃)] 100 parts by weight and 2,2'-methylenebis (4-methyl-
6-t-butylphenol) in a mixture with 0.3 parts by weight,
Nylon 6/6 ・ 6/6 ・ 10 in the ratio shown in Table 1 to 100 parts by weight of thermoplastic resin (polyacetal resin copolymer)
(Weight ratio 60/20/20) Terpolymer copolymerized polyamide resin and borate ester of monolauryl glycerin and carbon black as colorant ... 4 parts by weight (ethylene F black / BAS
Table 1 shows the results of blending and mixing a masterbatch resin composition prepared by mixing with a product manufactured by Company F) and obtaining and evaluating the characteristics thereof. The MI values shown in Tables 1 to 4 are ASTM standards.
It is the value measured under the D1238-E condition.

As can be seen from Table 1, in the master batch for 20-fold dilution, B component (polyamide resin) is added to the thermoplastic resin.
If the content exceeds 10 parts by weight (0.5 x 20), the date of occurrence of charring is accelerated, and if less than 0.02 parts by weight (0.001 x 20), MD
The prevention effect is lost.

Also, if the C component (borate monoester of monolauryl glycerin) is less than 0.2 parts by weight (0.01 × 20), there is no MD prevention effect, and if it exceeds 100 parts by weight (5 × 20), the thermal stability is greatly reduced and silver The streak generation time is shortened, and the thermal decomposition volatile content is also greatly increased.

Examples 11 to 17 A masterbatch resin composition was prepared in the same manner as in Example 1 except that the type of the B component (polyamide resin) was changed and the boric acid monoester of monostearyl glycerin was used as the C component. The mixture was blended, and its characteristics were obtained and evaluated.

 The results are shown in Table 2.

Comparative Example 7 The same procedure as in Example 11 was carried out using a masterbatch resin composition containing no polyamide resin and no boric acid ester of monoacylglycerin.

 The results are shown in Table 2.

Examples 18 to 25 As a polyacetal resin, a homopolymer [MI = 24.0
g / 10 minutes (190 ° C.)] and using a polyamide resin of the type shown in Table 3 and a boric acid monoester of monobehenyl glycerin as the C component.

Comparative Example 8 Table 3 shows the results obtained in the same manner as in Comparative Example 7 except that the homopolymer [MI = 24.0 g / 10 minutes (190 ° C.)] was used as the polyacetal resin in Comparative Example 7.

As can be seen from Tables 2 and 3, due to the synergistic effect of the polyamide resin and the boric acid ester of monoacyl glycerin, the occurrence of MD is significantly prevented, and the number of days of sticking and the silver streak occurrence time become longer, The amount of decomposed volatiles is also significantly reduced as compared with the case where the polyamide resin and the boric acid ester of monoacyl glycerol are not added.

These phenomena are the same whether the polyacetal resin is a copolymer or a homopolymer.

Examples 26 to 29 The thermoplastic resin (polyacetal resin copolymer) and the polyamide resin (nylon 6/6 ・ 6/6 ・) used in Example 1 were used.
10) and a boric acid monoester of monolauryl glycerin were used to prepare a masterbatch resin composition blended so that the masterbatch dilution ratio was 10, 40, 60 times.
The evaluation was carried out in the same manner as.

Further, as the thermoplastic resin, low density polyethylene (LDPE) was used in place of the polyacetal resin copolymer of Example 3.
Example 3 was carried out in the same manner as in Example 3 except that Ace Polyethylene M6525 / Ace Polymer Co., Ltd.

 The results are shown in Table 4.

As you can see from Table 4, the dilution factor of the masterbatch
MD generation was prevented even at 10, 40, 60 times as in Example 3, MD generation was prevented even when LDPE was used as the thermoplastic resin, and the number of days of charring and silver streak generation time increased, resulting in thermal decomposition. Volatile content is also reduced.

[Effect of the Invention] According to the present invention, a colored masterbatch for a polyacetal resin, which is a combination of a thermoplastic resin with a borate ester of glycerin monofatty acid ester and a colorant, is mixed with a polyacetal resin to obtain a colored polyacetal resin product. In the case of producing, it is possible to significantly suppress the formation of a mold deposit adhering to the inside of the mold during molding such as injection molding and improve the productivity of the molded product. Further, it is possible to easily obtain a polyacetal resin composition having excellent thermal stability and having less scorching on the screw.

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Claims (1)

[Claims] 1. From (A) 100 parts by weight of a thermoplastic resin, (B) from 0.001 × D parts by weight to 0.5 × D parts by weight (C) from 0.01 × D parts by weight of boric acid ester of monoacylglycerin to 5 parts by weight. X D parts by weight (D: represents the dilution ratio of the masterbatch) and a colorant, and a mold deposit-preventing colored masterbatch resin composition for a polyacetal resin.