JPH08311334A - Production of polyamide resin composition - Google Patents

Abstract

PURPOSE: To obtain a molded product containing a flame retardant sufficiently dispersed therein and extremely good in the appearance by extrusion-molding under a specific condition a composition containing a copolyamide and a triazine flame retardant in a specific ratio. CONSTITUTION: A composition comprising (A) a copolyamide containing polyamide-forming components wherein an acid component is a dimerized fatty acid, and (B) a triazine flame retardant [e.g. (iso)cyanuric acid, (cyanuric acid) melamine] in an A:B wt. ratio of 100:5 to 100:20 is produced by the use of an extruder. The shear rate (r: unit sec<-1> ) and specific energy (ESP: unit kwh/kg) of the extruder satisfy a relation: ESP>6.0×10<-3> ×r-0.022 (110<=r>=35).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polyamide resin composition. More specifically, the present invention relates to a method for producing a polyamide resin composition which is excellent in flexibility and flame retardancy and which does not contain a halogen element and is highly safe.

[0002]

2. Description of the Related Art It is known that a copolymerized polyamide containing a dimerized fatty acid component as a copolymerization component is excellent in flexibility and toughness (JP-A-54-71191).
Further, when such a copolyamide resin is used for electric / electronic applications, it is known to blend a triazine-based flame retardant and an orthophosphoric acid ester having a freezing point of −20 ° C. or lower in order to impart flame retardancy and cold resistance. (Japanese Patent Laid-Open No. 7-53863)
Issue). Triazine-based flame retardants, when melt-mixed with the resin using an extruder, usually appear as spots on the product after kneading, which deteriorates the appearance and the like,
There is a problem that the commercial value of the resin product is reduced.

Therefore, as a method for improving the dispersibility of the triazine-based flame retardant in the resin composition, the screw rotation speed (shear speed) of the extruder in which the triazine-based flame retardant is pulverized before being melt-mixed in the extruder. A method such as increasing the amount of the bisamide compound or blending the bisamide compound in an amount of about 0.01 to 3 parts by weight with respect to the composition has been adopted. However, the method of crushing has a drawback that the cost is increased, and further, the feed performance of the triazine-based flame retardant that has been crushed, variation in quality due to adhesion to pipes, deterioration of production stability and the like are likely to occur. In addition, the method of increasing the screw rotation speed (shear rate) lowers the solvent viscosity of the resin, which reduces the shearing force applied to the triazine-based flame retardant, which makes it difficult to achieve fine dispersion and causes decomposition. It also had the drawback of being easy. Further, the method of adding a bisamide compound also has a problem that the triazine-based flame retardant tends to be insufficiently finely dispersed depending on the kneading conditions.

[0004]

The object of the present invention is to use a copolyamide containing a polyamide-forming component whose acid component is a dimerized fatty acid as a copolymerization component and a triazine-based flame retardant using an extruder. It is an object of the present invention to provide a method for producing a polyamide resin composition, which can sufficiently disperse a triazine flame retardant in the resin composition when producing the resin composition and can give a molded article having an extremely good appearance.

[0005]

[Means for Solving the Problems] When the kneading of a copolyamide and a triazine flame retardant is carried out by an extruder, the inventors have selected kneading conditions so that the shear rate and the specific energy are kept in a constant relationship. The inventors have found that the above problems can be solved by doing so and have reached the present invention. That is, the gist of the present invention is a copolymerized polyamide containing a polyamide-forming component whose acid component is a dimerized fatty acid as a copolymerization component {hereinafter (A)
It is called an ingredient. } And a triazine-based flame retardant {hereinafter referred to as component (B). } And the component (A) to the component (B) in a weight ratio of 100: 5 to 100: 20, the shear rate (γ of the extruder : Unit sec ^-1 ) and specific energy (ES
P: unit kwh / kg) satisfies the following relational expressions (1) and (2).

[0006]

## EQU3 ## ESP> 6.0 × 10 ^-3 × γ-0.022 (1) 110 ≧ γ ≧ 35 (2)

The present invention will be described in detail below. The polyamide resin composition of the present invention contains the component (A) and the component (B). The component (A) is a polyamide-forming component whose main component is a lactam having three or more membered rings, a polymerizable ω-amino acid, or a polyamide-forming component obtained by polycondensation of a dibasic acid and diamine. It contains a polyamide-forming component which is a dimerized fatty acid component. As a raw material of the polyamide forming component which is the main component,
Specifically, ε-caprolactam, enanthlactam,
Lactams such as capryl lactam, lauryl lactam, α-pyrrolidone, α-piperidone, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, ω-amino acids such as 11-aminoundecanoic acid, adipic acid , Glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, undecanedioic acid,
Dodecadioic acid, Hexadecadionic acid, Hexadecenedionic acid, Eicosandionic acid, Eicosadienedionic acid, Diglycolic acid, 2,2,4-Trimethyladipic acid, Xylylenedicarboxylic acid, 1,4-Cyclohexanedicarboxylic acid, Dibasic acids such as terephthalic acid and isophthalic acid, hexamethylenediamine, tetramethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylene Examples thereof include diamines, bis- (4,4′-aminocyclohexyl) methane, and diamines such as metaxylylenediamine.

Specific examples of the polyamide composed of such a polyamide-forming component include, for example, nylon 4,6.
7, 8, 11, 12, 6.6, 6.9, 6.10, 6.
11, 6.12, 6T, 6 / 6.6, 6/12, 6/6
Examples include T. The dimerized fatty acid used as the copolymerization component is an unsaturated fatty acid, for example, having 8 to 2 carbon atoms.
A polymerized fatty acid obtained by polymerizing a monobasic fatty acid from natural fats and oils or a synthetic monobasic fatty acid consisting of 4 and having at least one double bond or triple bond is used. Specific examples thereof include dimers of linolenic acid and linoleic acid.

[0009] Commercially available polymerized fatty acids usually contain dimerized fatty acid as a main component and also contain a raw material fatty acid monomer and trimerized fatty acid, but the dimerized fatty acid content is 70% by weight. % Or more, preferably 95% by weight or more, and more preferably 98% by weight or less. Commercial products are also called dimer acids. Further, in the present invention, commercially available polymerized fatty acid may be distilled to increase the content of dimerized fatty acid, or may be used by hydrogenating to reduce the degree of unsaturation. .

As the diamine component forming a copolymerization component with dimerized fatty acid, ethylenediamine, 1,4-
Aliphatic diamines such as diaminobutane, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, bis (4,4 ′) Examples thereof include alicyclic diamines such as -aminocyclohexyl) methane and aromatic diamines such as metaxylylenediamine.

The content of the dimerized fatty acid in the component (A) is 1 to 80% by weight, preferably 10 to 50% by weight, based on the whole copolymerized polyamide. If this amount is small, the effect of improving flexibility cannot be expected. On the contrary, if the amount is too large, the rigidity deteriorates. The relative viscosity (ηrel) of the component (A), which is the copolyamide in the present invention, is 1.8 to 3.
6, preferably 2.4 to 3.3. The relative viscosity is measured at 25 ° C. using a Ubbelohde viscometer in a solution of 0.4 g of a copolyamide having a water content of 0.3% or less in 40 ml of m-cresol. In the component (A), the polyamide terminal may be alkylated, and in that case, the terminal alkyl group is preferably a hydrocarbon group having 6 to 22 carbon atoms. In addition to the hydrocarbon group, the terminal group of the component (A) includes an amino group and a carboxyl group derived from the raw material of the component (A), and the total number of terminal groups is the above-mentioned hydrocarbon group and amino group. It is the sum of the numbers of groups and carboxyl groups.

The number of the above-mentioned hydrocarbon groups in the case of terminal alkylation is 25 equivalent% or more, preferably 30 equivalent% or more of the total number of terminal groups. Further, industrially, the amount is preferably 40 to 95 equivalent%, more preferably 50 to 90 equivalent%. Here, the number of terminal hydrocarbon groups is measured by gas chromatography after hydrolyzing the polyamide with hydrochloric acid. The amino group is measured by dissolving polyamide in phenol and titrating with 0.05N hydrochloric acid. The carboxyl group is measured by dissolving polyamide in benzyl alcohol and titrating with 0.1N caustic soda.

In the above-mentioned terminally alkylated copolymerized polyamide, the above polyamide raw material is used as the polyamide having 7 to 2 carbon atoms.
It can be obtained by polycondensation in the presence of the monocarboxylic acid of 3. The component (A) may be produced by the usual method using the above-mentioned polyamide raw material. Further, in order to prevent fusion of the pellets of the component (A) and improve mold releasability, polyalkylene oxide can be added. The polyalkylene oxide is preferably a polyalkylene oxide having an alkylene chain having 2 to 4 carbon atoms, and specific examples thereof include polyethylene oxide, polypropylene oxide, polytetramethylene oxide and the like. The molecular weight is usually 300 to 600.
It is preferably about 0.

As a method of adding polypropylene oxide to the component (A), polyalkylene oxide may be added to the component (A) and melt-mixed by an ordinary method. However, since the polyalkylene oxide has poor dispersibility, Usually (A)
It is preferred to add the polyalkylene oxide at the stage of making the components. In this case, the polyalkylene oxide can be added, for example, at any stage from the start of the reaction of the raw material of the component (A) to the start of the polycondensation reaction under reduced pressure. The amount of polyalkylene oxide added is usually 0.1 to 10% by weight, preferably 0.5, relative to the component (A).
10 to 10% by weight. As the component (B), a general formula

[0015]

Embedded image

(Wherein R represents a hydrogen atom or an alkyl group which may be different from each other),
Examples include melamines and melamine cyanurate. Hereinafter, these compounds will be specifically described. (1) Compound represented by the general formula (II) Cyanuric acid, trimethylcyanurate, triethylcyanurate, tri (n-propyl) cyanurate, methylcyanurate, diethylcyanurate and the like can be mentioned. (2) Compound represented by the general formula (III) Isocyanuric acid, trimethyl isocyanurate, triethyl isocyanurate, tri (n-propyl) isocyanurate, diethyl isocyanurate, methyl isocyanurate and the like can be mentioned.

(3) Melamines The melamines referred to in the present invention include not only melamine but also melamine derivatives, compounds having a structure similar to melamine or condensates of melamine. Specific examples of such compounds include melamine, ammelide, ammeline, formoguanamine, guanylmelamine, cyanomelamine, arylguanamine, melam, melem, and melon.

(4) Melamine cyanurate Melamine cyanurate is an equimolar reaction product of cyanuric acid and melamine. For example, an aqueous solution of cyanuric acid and an aqueous solution of melamine are mixed and reacted under stirring at 90 to 100 ° C. And can be obtained by filtering the formed precipitate. This is a white solid, and it is preferable to use it after pulverizing it into a fine powder. Of course, it is also possible to use a commercially available product as it is or after crushing it. Further, some of the amino groups or hydroxyl groups in melamine cyanurate may be substituted with other substituents. Of these triazine-based flame retardants, cyanuric acid, isocyanuric acid, melamine, and melamine cyanurate are preferable. In particular, melamine cyanurate is most preferable because there is no inconvenience such as so-called blooming in which a decomposed product appears on the surface of a molded product.

The ratio of the component (A) to the component (B) contained in the polyamide resin composition is 100: 5 by weight.
It is 100: 20. If the amount of component (B) is less than the above range, the flame retardant effect is insufficient, and if it is more than the above range, saturation is likely to occur and surface defects in the molded product due to blooming on the surface are likely to occur. A more preferable range of the component (A) to the component (B) is 100: 6 to 100: 15. As the components contained in the polyamide resin composition of the present invention, in addition to the components (A) and (B), (A)
A polyamide resin other than the component, a flame retardant other than the component (B),
Impact modifiers, stabilizers, release agents, nucleating agent fillers, coloring agents and the like can be mentioned.

In the present invention, at least the component (A) and the component (B) are melt-kneaded using an extruder to produce a polyamide resin composition. The extruder used in the present invention is usually a single-screw extruder, a twin-screw co-rotating screw extruder, a two-screw counter-rotating screw extruder, etc., a two-screw co-rotating screw extruder or a two-screw different-direction rotating extruder. A screw extruder is preferred. In these extruders,
In order to finely disperse the component (B) in the component (A), it is necessary that the shear rate and the specific energy satisfy the relational expressions (1) and (2) below.

[0021]

Equation 4] ^{ESP> 6.0 × 10 -3 × γ} -0.022 (1) 110 ≧ γ ≧ 35 (2)

Shear rate (γ) and specific energy (ESP)
A more preferable relational expression with and is (3) below.

[0023]

[Equation 5] ESP ≧ 6.0 × 10 ⁻³ × γ−0.017 (3)

If the shear rate γ is less than 35, the number of spots based on the component (B) increases, which is not preferable in appearance and 1
When it exceeds 10, the heat generated by shearing causes decomposition of the component (B), and the shearing force applied to the component (B) in order to lower the melt viscosity of the resin becomes small, which makes fine dispersion difficult.
In order for the shear rate and the specific energy in the extruder to satisfy the above formula, the kneading conditions are (1) screw configuration (for example, kneading disk layout) (2)
This can be achieved by appropriately selecting the conditions such as barrel set temperature (3) discharge amount. Incidentally, empirically, when the discharge amount (Q) is changed by scale-up, scale-down, etc., an error of about ± 0 to 10% may occur in the specific energy. The maximum specific energy is usually 1.
It is a range not exceeding 0 kwh / kg. Preferably 0.
It is 8 kwh / kg or less.

[0025]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof. (1) Evaluation of Dispersibility of Triazine-based Flame Retardant (Melamine Cyanurate) in Polyamide Resin Composition Pellets of polyamide resin composition produced by kneading the resin composition with an extruder are dried and then heated and pressed (Toyo Seiki Co., Ltd.)
And preheat at 210 ° C for 1 minute, weight 1gr thickness about 30μ
m film was formed. Then, using a magnifying glass (2 times), the maximum length (on one side) of the number of spots (number / 1 gr) of meminine cyanurate in the film was about 20 μm.
m or more was measured, and 30 or less were regarded as good dispersion. It should be noted that the maximum lengths shown in this example were all about 60 μm or less. (2) Specific energy (kwh / kg) and shear rate (s
ec ^-1 )

[0026]

(Equation 6)

Peripheral speed (rad / s). Discharge rate (kg / h
r). Dividing by 101.97 is kg ・ m ・ rad /
This is because sec is converted to kw. The peripheral speed can be calculated by the following formula.

[0028]

(Equation 7)

[0029]

(Equation 8)

(3) (A) used in Examples or Comparative Examples
Table 1 shows the composition and relative viscosity of the components.

[0031]

[Table 1]

[Examples 1 to 5 and Comparative Examples 1 to 14] Table-
The pellets of the copolyamide {(A) component} shown in 2 are extruded by a feeder (TEX44SS manufactured by Japan Steel Works).
-30AW-2V) and simultaneously melamine cyanurate (trade name MX44 manufactured by Ogaki Kasei Co., Ltd.) {(B) component}
Was fed to the same position of the extruder with a feeder so that the weight ratio of the component (A) to the component (B) was 100: 10, and
Melt kneading was performed so that the shear rate and the specific energy shown in 2 were obtained. The pellets of the polyamide resin composition obtained by melt-kneading are dried in a vacuum dryer at 80 ° C. for 24 hours, and then the dried pellets obtained are formed into a film with a heating press machine (210 ° C.), and melamine cyanurate is mixed with a magnifying glass. The number of spots was visually measured. Table 2 shows the results. The relationship between the number of spots, specific energy and shear rate is shown in Fig. 1. When the number of spots is 30 or less, it can be said that melamine cyanurate is well dispersed in the polyamide resin composition.

[0033]

[Table 2]

[0034]

According to the method of the present invention, it is possible to obtain a resin composition which improves the dispersibility of additives such as a flame retardant and gives a molded article having a good appearance.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between specific energy and shear rate and dispersibility of melamine cyanurate in Examples and Comparative Examples of the present invention. ◯: Number of spots ≦ 30 ×: Number of spots> 30

Claims (7)

[Claims] 1. A copolymerized polyamide containing a polyamide-forming component whose acid component is a dimerized fatty acid as a copolymerization component {hereinafter referred to as (A) component. } And a triazine-based flame retardant {hereinafter referred to as component (B). } And the component (A) to the component (B) in a weight ratio of 100: 5 to 100: 20, the shear rate (γ of the extruder : Unit sec ^-1 ) and specific energy (ESP: unit kwh / kg) are as follows (1)
And a method for producing a polyamide resin composition, which satisfies the relational expressions (2). ## EQU1 ## ESP> 6.0 × 10 ^-3 × γ-0.022 (1) 110 ≧ γ ≧ 35 (2) 2. The component (A) is a lactam having three or more membered rings,
A copolymerized polyamide comprising a polyamide-forming component obtained by polycondensation of a polymerizable ω-amino acid or dibasic acid and a diamine, and a polyamide-forming component obtained by polycondensation of a dimerized fatty acid and a diamine, The method for producing the polyamide resin composition according to claim 1. 3. The method for producing a polyamide resin composition according to claim 1, wherein the content of the dimerized fatty acid is 1 to 80% by weight in the component (A). 4. The method for producing a polyamide resin composition according to claim 1, wherein the component (B) is cyanuric acid, isocyanuric acid, melamine or melamine cyanurate. 5. The relative viscosity of the component (A) is 2.4 to 3.3.
The method for producing a polyamide resin composition according to any one of claims 1 to 4, wherein 6. A polyamide resin composition according to claim 1, wherein the weight ratio of the component (A) to the component (B) is 100: 6 to 100: 15. Manufacturing method. 7. The specific energy (ESP: kwh / k)
The method for producing a polyamide resin composition according to any one of claims 1 to 6, wherein g) and the shear rate (γ: unit sec ^-1 ) satisfy the following relational expression (3). [Number 2] ^{ESP ≧ 6.0 × 10 -3 × γ} -0.017 (3)