JPS63260409A - Manufacture of poly-epsilon-caprolactam molded product - Google Patents

Abstract

PURPOSE:To make the title molded product into one which is of high crystallizability and superior in rigidity, tenacity and heat resistance, by a method wherein reaction injection molding of lactam is performed by specifying also a kind and quantity of a catalyst and activator. CONSTITUTION:Reaction injection molding of substantially anhydrous epsilon- caprolactam is performed in the presence of at least a kind of 0.1-3 mol% of catalyst selected out of an alkali metal, an alkali earth metal, a hydride, hydroxide and oxide of the said metal, carbonate, an alkoxy compound, an alkyl compound, an allyl compound, a Grignard reagent, an aluminum compound and salts of those metals and lactam and at least a kind of 0.01-2 mol% of activator selected out of acyl lactam and a compound which is capable of becoming acyl lactam by reacting with the lactam. Then specific gravity, crystallinity, a mean diameter of a spherulite and etar of poly-epsilon-caprolactam manufactured are made 1.142-1.165, 35-50%, 25mu or larger and 3 or larger respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application Fields The present invention produces highly crystalline, rigid, and
The present invention relates to a method for producing poly-ε-caprolactam molded products having excellent toughness and heat resistance.

It is already a well-known technology that poly-ε-caprolactam molded products can be produced in a short time by reaction injection molding of lactams using an alkali catalyst and an activator, and many catalysts have been used to date. and activators have been reported. Poly ε-caprolactam molded products obtained by this reaction injection molding method have a higher degree of crystallinity than molded products obtained by melt molding melt-polymerized poly ε-caprolactam, and have higher strength and
Although it has the characteristics of good rigidity and heat resistance, it has been pointed out that it has the disadvantage of being relatively brittle.

Having serious defects in mechanical properties is a major drawback in practical use, and this point is
This is one of the reasons why demand for caprolactam molded products is not growing.

As a means to improve the brittleness of polyε-caprolactam molded products obtained by reaction injection molding, methods of copolymerizing polyalkylene glycol (for example, Japanese Patent Publication No. 54-40120), low molecular weight A method of polymerizing in the presence of polybutadiene (for example, JP-A-54-39
493), a method of polymerization in the presence of a dialkylimidazolidinone compound (for example, JP-A-58-6372),
Publication No. 3) and the like are publicly known.

<Problems to be solved by the invention> However, although the method of introducing these copolymer components or plasticizer components improves the impact resistance, on the other hand, the strength of the molded product and
Polyε obtained by reaction injection molding has a significant decrease in rigidity.
-It greatly impairs the characteristics of caprolactam molded products. Therefore, polyε-
At present, there have been almost no attempts to achieve a well-balanced combination of strength, rigidity, impact resistance, and toughness in caprolactam molded products.

The present inventors aimed to produce molded products with improved toughness without sacrificing the excellent strength, rigidity, and heat resistance of reaction injection molding polyε-caprolactam. The correlation between this and the physical properties and physical properties of polyε-caprolactam was investigated.

In other words, the problem that the present inventors are trying to solve is to establish a method for producing poly-ε-caprolactam molded products with excellent balance of physical properties and high practical value by reaction injection molding.

Means for Solving the Problems The present inventors have determined that the density, crystallinity, spherulite diameter, and relative viscosity of the polyε-caprolactam to be produced can be improved by specifying the type and strength of the catalyst and activator. The present invention was achieved by discovering that the temperature was within a suitable range, and as a result, it was possible to obtain a molded product with excellent physical properties such as strength, rigidity, toughness, and heat resistance in a well-balanced manner.

That is, the present invention provides the following (I) for ε-caprolactam.
) at least one catalyst selected from 0.1 to 3 mol%
and the production of a patented ε-caprolactam molded article characterized in that substantially anhydrous ε-caprolactam is subjected to reaction injection molding with 0.01 to 2 mol % of at least one activator selected from the following (IF): The present invention provides a method.

(I> Catalysts: alkali metals, alkaline earth metals, hydrides, hydroxides, oxides, carbonates, alkoxy compounds, alkyl compounds, aryl compounds, Grignard reagents, aluminum compounds of these metals, and combinations of these metals with lactams. Salt (n) Activator: Acyl lactam and compound that can react with lactam to form acyl lactam Characteristics Specific gravity of poly ε-caprolactam: 1,142 to 1.165 (d) Crystallinity of poly ε-caprolactam: 35 ~50
% Average diameter of spherulites of polyε-caprolactam: 25 μ or more (d) ηr of polyε-caprolactam: 3 or more Although this is generally known, the feature of the manufacturing method of the present invention is that it breaks down the trade-off between strength, rigidity, and impact resistance in the molded products manufactured by the method of the present invention.

The technical point is that by specifying the type and amount of the catalyst and activator, large-diameter spherulites can be formed densely, and polyε-caprolactam with a relatively high molecular weight can be obtained. The superior strength, rigidity, and heat resistance of molded products depend on their high degree of crystallinity, and their high impact resistance is attributed to the dense distribution of high-molecular-weight polyε-caprolactam crystals. It is.

Furthermore, in the combination of the catalyst and activator of the present invention, if the amount exceeds the amount limited by the present invention, the diameter of the spherulites produced will become smaller and the molecular weight will also decrease.

The present invention is characterized in that there is a positive correlation between the molecular weight of polyε-caprolactam and the diameter of the produced spherulites.

The ε-caprolactam used in the present invention can be produced by any method, but it is required to be substantially anhydrous. It is also possible to add small amounts of other ω-lactams as copolymerization components to the ε-caprolactam of the present invention as long as the basic characteristics thereof are not impaired; examples of these include 2-pyrrolidone, valerolactam, and enanthate. Examples include lactam, capryllactam, and laurolactam. It is also possible to copolymerize small amounts of polyols, examples include polyethylene glycol, polypropylene glycol, polyoxyethylene/oxypropylene copolymer, polytetramethylene glycol, polycaprolactone diol, polybutadiene diol, polybutadiene Examples include diol hydrogenated products and polyoxyethylene/dimethylsiloxane copolymers.

The catalysts used in the present invention include alkali metals, alkaline earth metals, hydrides, hydroxides, oxides, carbonates,
alkoxy compounds, alkyl compounds, aryl compounds,
At least one compound selected from Grignard reagents, aluminum compounds, and salts of these metals and lactams; particularly preferred metals include lithium, sodium,
These are potassium, magnesium, calcium and aluminum. Specific examples of catalysts particularly useful in the present invention include lithium hydride, methyllithium, lithium methoxide, sodium, sodium hydride, sodium methoxide, sodium ethoxide, sodium hydroxide, sodium carbonate, sodium lactamate, Potassium, potassium hydroxide, potassium methoxide, potassium ethoxide, potassium hydroxide, potassium carbonate, potassium lactamate, calcium hydroxide, ethylmagnesium bromide, butylmagnesium bromide, propylmagnesium bromide, phenylmagnesium bromide,
Ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, phenylmagnesium chloride and the reaction products of these Grignard reagents with ε-caprolactam, triethylaluminum, diethylchloroaluminum, ethyldichloroaluminum, aluminum propoxide and these aluminum compounds and ε- Examples include reaction products with caprolactam. In order to obtain the poly ε-caprolactam molded article of the present invention, the amount of catalyst added must be within the range of 0.1 to 3 mol%, and 0.3 to 2.5 mol% based on ε-caprolactam. It is preferable that it is in the range of .

If the amount of catalyst added is less than 0.1 mol, the polymerization activity will be extremely reduced, which is undesirable. On the other hand, if the amount of catalyst added exceeds 3 mol%, the amount of metal ions remaining in the polyε-caprolactam molded product will increase. This is undesirable because it coordinates with the amide group, which lowers the crystallinity of the nylon, making it impossible to obtain a molded article with desired physical properties.

The activator used in the present invention is a compound that produces an acyllactam compound containing one or more structural units in the molecule in which the hydrogen atom on the nitrogen atom of ε-caprolactam is replaced with a carbonyl group. Acyllactam compounds are broadly classified into those in which the acyllactam unit is directly bonded to a carbon atom and those in which the acyllactam unit is directly bonded to a heteroatom.

Examples of the former include acetylcaprolactam, adipoylbiscaprolactam, sebacoylbiscaprolactam,
Examples of these acyl lactams include terephthaloyl biscaprolactam, 2-chloroterephthaloyl biscaprolactam, 2,5-dichloroterephthaloyl biscaprolactam, inphthaloyl biscaprolactam, and dibenzoyl biscaprolactam. Examples of the precursor include corresponding carboxylic acids and halides thereof. On the other hand, excellent examples include hexamethylene-1,6-biscarbamide caprolactam, tolylene-2,4(2,6)-biscarbamide caprolactam, and their precursors include hexamethylene diiso yanate, tolylene diisocyanate,
Examples include diphenylmethane diisocyanate and polymethylene polyphenylisocyanate.

In the present invention, it is particularly preferable to use the former acyllactam compound. The amount of the activator added must be within the range of 0.01 to 2 mol%, preferably within the range of 0.05 to 1.5 mol%, based on ε-caprolactam. If the amount of the activator added is less than 0.01 mol%, the polymerization rate and polymerization rate will drop significantly, which is undesirable. If the amount added exceeds 2 mol%, the ηr of the polyε-caprolactam produced will be less than 3. However, it is not possible to obtain molded products with sufficient properties.

The reaction injection molding referred to in the present invention is usually carried out by a known method. For example, a catalyst and an activator are added to and mixed with molten lactam heated to 80 to 150°C, and the mixture is immediately heated to 100 to 180°C in advance. injected into the mold,
This can be carried out by polymerizing for 0.5 to 30 minutes.

The production method of the present invention applies the specified type and amount of catalyst and activator to the reaction injection molding method of ε-caprolactam, thereby improving density, crystallinity, average diameter of spherulites, A polyε-caprolactam molded article in which the ηr of nylon is extremely well controlled can be obtained.

The definitions of specific gravity, crystallinity, average spherulite diameter, and ηr (relative viscosity) as used in the present invention indicate physical properties determined by ordinary technical terminology, and the methods for measuring each property are as described below. be.

In the present invention, it is necessary to simultaneously satisfy the specific gravity, crystallinity, average diameter of spherulites, and ηr of polyε-caprolactam. Since the physical properties of this material are impaired, it is not considered as a counterweight to the present invention.

The specific gravity of polyε-caprolactam is 1.142 to 1.16
5, and preferably 1.144 to 1.160.

If the specific gravity is less than 1.142, the rigidity and heat resistance will be unsatisfactory and unsuitable. On the other hand, molded products of polyε-caprolactam with a specific gravity exceeding 1.165 will have too many dimensional changes and are not practical.

The crystallinity of poly ε-caprolactam has a relationship corresponding to its specific gravity, and needs to be 35 to 50%, preferably 36 to 48%.

If the crystallinity is less than 35%, the crystallinity is low and the rigidity and heat resistance are unsatisfactory, which is undesirable.On the other hand, if the crystallinity is 50%
If the temperature is exceeded, the molded product may become deformed.
Undesirable.

The average diameter of the spherulites of polyε-caprolactam must be 25μ or more, preferably 28μ or more.

When the average diameter of the spherulites is less than 25 μm, the rigidity and strength of the molded product are unsatisfactory. Although there is no particular upper limit to the average diameter of the spherulites, it is approximately 100 μm at most in the sense that it is actually possible.

The ηr of polyε-caprolactam is an important property that governs the toughness of the molded product, and is required to be 3 or more, preferably 3.5 or more.

If ηr is less than 3, the toughness and impact resistance are insufficient, but if conditions are selected, polyε-caprolactam with ηr of about 50 can be prepared.

The higher the ηr, the better the toughness, rigidity, and heat resistance, but in general, to obtain a molded product with a high ηr, it is necessary to take a long polymerization time, and the production efficiency of the molded product depends on the physical properties. It is realistic to determine the optimal point by balancing the following.

The poly ε-caprolactam molded product obtained by the production method of the present invention has good strength, rigidity, heat resistance, and impact resistance, and is of high practical value.

The polyε-caprolactam molded product of the present invention may contain other additives such as pigments, dyes, reinforcing materials, fillers, heat-resistant agents, oxidation, etc., as long as they do not impair properties such as strength, rigidity, heat resistance, and impact resistance. inhibitor, weathering agent, mold release agent, flame release agent, foaming agent,
Antistatic agents and the like can be added and introduced.

<Example> The present invention will be explained in more detail by giving examples below. The characteristics described in the following examples were measured by the following method.

(1) Specific gravity: A small piece of the molded product was placed in a density gradient tube prepared using a toluene/carbon tetrachloride mixture as a solvent, and the temperature was 25°C.
It was measured with

(2) Crystallinity: Cut out a small piece from the center of the molded piece,
It was calculated from the diffraction peak intensity of wide-angle X-ray diffraction.

(3) Average diameter of spherulites: A thin piece was cut from the center of the molded piece and observed with a polarizing microscope.

(4) ηr: JIS K6810 (5) Tensile properties: ASTM D63B (6) Bending properties: ASTM D790 (7) Tensile impact strength: ASTM
D1B22 (8) Heat distortion temperature: ASTM D64
8 Example 1 113 g (1.0 mol) of anhydrous ε-caprolactam was added to 9
Heat and melt at 0°C, add 0.5 mol of phenylmagnesium bromide (tetrahydrofuran solution),
Benzene as a by-product and tetrahydrofuran as a solvent were distilled off under reduced pressure.

Next, adipoyl biscaprolactam 0.679 (0,
2 mol%) and quickly mixed, the mixture was
The mixture was placed in a mold preheated to 0°C and polymerized for 10 minutes. When the mold was opened for 10 minutes, a molded piece with a good appearance was obtained, which had a specific gravity of 1.148, a crystallinity of 40%, ηr of polyε-caprolactam = 13.5, and a sphere in the molded product. As shown in the photograph of spherulites observed under a polarizing microscope in Fig. 1, spherulites with large diameters were densely formed.

The physical properties of this product are as shown in Table 1, and it was found to be a molded product with high practical value and excellent rigidity, strength, heat resistance, and impact resistance.

Comparative Example 1 A molded product was obtained by polymerization/molding in the same manner as in Example 1 except that the amount of phenylmagnesium bromide added was changed to 5 mol %. However, this molded product has a specific gravity of 1,135,
It has a low crystallinity of 29%, resulting in a bending modulus of 30.0 OON5F/d, a heat distortion temperature of 72°C, and a high rigidity.
The heat resistance was greatly reduced and the properties were insufficient.

Comparative Example 2 The amount of activator adipoyl biscaprolactam added was 8
．． Polymerization/molding was carried out in exactly the same manner as in Example 1 except that 41 g (2.5 mol %) was used to obtain a molded product.

However, this material has a low η' of 2.1, and the average diameter of the spherulites is as small as 15 μ, as shown in the photograph of spherulites observed under a polarizing microscope in Figure 2. Therefore, the tensile impact strength is 750 cI.
The molded product had an insufficient It/cd.

Example 2 Ethylmagneium bromide as a catalyst, 1°0 mol%
Polymerization and molding were carried out in the same manner as described in Example 1, except that 0.5 mol % of terephthaloyl biscaprolactam was used as an activator, to obtain a molded product with a good surface appearance. The initial characteristics of this product are shown in Table 1,
It was found that the specific gravity, crystallinity, and ηr1 spherulite diameter were controlled, and the properties were excellent.

Effects of the invention as shown in Table 1> As mentioned above, when producing polyε-caprolactam molded products by reaction injection molding polyε-caprolactam, the catalyst and activator are specified and the resulting polyε-caprolactam is
By controlling the ηr, density, crystallinity, and spherulite diameter of caprolactam, we can produce polyε-caprolactam molded products with balanced strength, rigidity, heat resistance, and impact resistance for excellent practical use (iii). It is now possible to

[Brief explanation of the drawing]

FIG. 1 is a spherulite photograph of the molded products obtained in Example 1 and Comparative Example 2, taken with a polarizing microscope vA.

Claims (1)

[Claims] 0.1 to 3 mol% of at least one catalyst selected from the following (I) and the following (I) based on ε-caprolactam:
I) at least one activator selected from 0.01~
1. A method for producing a poly ε-caprolactam molded article having the following characteristics, which comprises reaction-injection molding substantially anhydrous ε-caprolactam at a concentration of 2 mol %. (I) Catalysts: alkali metals, alkaline earth metals, hydrides, hydroxides, oxides, carbonates, alkoxy compounds, alkyl compounds, aryl compounds, Grignard reagents, aluminum compounds, and combinations of these metals with lactams. Salt (II) activator: acyllactam and compound that can react with lactam to form acyllactam Characteristics (a) Specific gravity of polyε-caprolactam: 1.142 to 1.165 (b) Crystallinity of polyε-caprolactam :35~50
% (c) Average diameter of polyε-caprolactam spherulites: 25μ
(d) ηr of polyε-caprolactam: 3 or more