JPH0764977B2 - Lactam composition for reaction injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a lactam composition having excellent moldability and operability, which has high rigidity, impact resistance, and dimensional stability. The feature is that a molded product excellent in can be manufactured.

<Prior Art> It is already well known that lactams are anionically polymerized with an alkali catalyst and an activator to obtain a polylactam molded product in a short time.
Products such as gears, containers, and outer housings have been put to practical use.

Recently, so-called nylon RIM (reaction injection molding / Reactio
n Injection Molding) has attracted attention as a technique, and a technique for mixing two liquids and immediately transferring them into a mold for polymerization is being studied. In this nylon RIM system, the operation of circulating the melt of the raw material lactam in the pipe or mixing the lactam component mainly containing the catalyst and the lactam component mainly containing the activator in the mixing chamber (mixing head). However, since the viscosity of the melt of lactam is basically too low like water, gas (air or an inert gas such as nitrogen or argon for sealing) is bubbled during liquid transfer, mixing and circulation operations. As a result, the molded article is likely to be clogged, and as a result, voids are formed in the molded article, which causes unfavorable deterioration of the physical properties. In addition, bubbles in the lactam stock solution may cause an error in weighing during mixing, which may deteriorate the polymerizability.

Up to now, these problems have been solved mainly by designing the molding machine and its parts, and reducing the pressure inside the mold for defoaming. Examples of the prior art include a method of forming a gas vent hole in a molding die that communicates with a cavity portion (JP-A-59-38043), and a method of using a die having a special slidable holding lid (JP-A-Sho). 56-33916),
Method using a mold having a liquid retention part (Japanese Patent Laid-Open No. 59-10693)
No. 9 gazette), etc., but these are all designed to be solved by the design of the molding machine and the mold as described above, and the approach from the viewpoint of the raw material composition has hardly been made so far. Is.

<Problems to be Solved by the Present Invention> The present inventors suppress the inclusion of bubbles by controlling the viscosity of the raw material lactam melt to an appropriate level, formability,
The purpose of this study was to obtain a lactam composition having excellent operability and polymerizability, and further to obtain a molded article having good rigidity, impact resistance, and dimensional stability.

That is, the problem to be solved by the present invention is a lactam composition having excellent controllability of the undiluted solution viscosity, moldability and operability, and preparation of a lactam composition capable of obtaining a polymerized molded article having excellent physical properties. It is in.

<Means for Solving Problems> The above-mentioned problem is that a lactam as a reaction injection molding lactam composition is mixed with an inorganic reinforcing material, particularly a fibrous inorganic reinforcing material and a non-fibrous inorganic reinforcing material in a specific ratio, and further, It has been found to be achieved by using a combination of specific catalysts and activators.

That is, the present invention relates to (A) a substantially anhydrous lactam (which may optionally contain a polyol), (B) a lactam, and at least one catalyst obtained from (I) below.
0.1 to 3 mol% and / or at least one activator selected from the following (II) with respect to (C) lactam 0.01
5 to 35 mol% in total of 30 to 70% by weight, (D) fibrous inorganic reinforcing material 5 to 35% by weight and (E) calcium carbonate, wollastonite, silica, glass beads, magnesium oxide,
At least one isotropic non-fibrous inorganic reinforcing material selected from hollow glass balloons and shirasu glass balloons 15
The present invention provides a lactam composition for reaction injection molding, which comprises -60% by weight.

(I) Catalysts: alkali metals, alkaline earth metals, hydrides, hydroxides, oxides, carbonates, alkoxy compounds, alkyl compounds, aryl compounds, Grignard reagents, aluminum compounds and salts of these metals with lactams. , (II) Activator: Acyl lactam and a compound that can react with lactam to form an acyl lactam It is common to add a lactam and an inorganic reinforcing material, and subject this to reaction injection molding to obtain a molded article containing the reinforcing material. It is well known, but the feature of the present invention is that the fibrous inorganic reinforcing material is used together with the isotropic and the non-fibrous inorganic reinforcing material, and the both are used in a certain ratio, so that the fluidity and the operability are not provided. It has been found that an excellent lactam composition can be obtained. Furthermore, this lactam composition can be reacted with a specific combination of a catalyst and an activator. When molded, a combination of fibrous inorganic reinforcing material and isotropic non-fibrous inorganic reinforcing material acts extremely effectively for balancing strength, rigidity, impact resistance, dimensional stability, etc. The point is that the product is obtained. Type of reinforcing material specified in the present invention, mixing ratio, combination of catalyst and activator,
The set target of the present invention can be achieved only when the usage amount is satisfied.

The main constituent of the (A) lactam used in the present invention is ε-caprolactam. The lactam can be produced by any method, but it needs to be substantially anhydrous.

It is also possible to add a small amount of other ω-Lactau as a copolymerization component to ε-caprolactam as long as its basic characteristics are not impaired.Examples of these include 2-pyrrolidone, valerolactam, enantolactam and Lactam, laurolactam and the like can be copolymerized by adding a polyol as required, and examples of the polyol include polyethylene glycol, polypropylene glycol, polyoxyethylene / oxypropylene copolymer, polytetramethylene glycol, Polycaprolactone diol, polybutadiene diol, hydrogenated polybutadiene diol, polyoxyethylene / dimethyl siloxane copolymer, polypropylene triol, polytetramethylene triol, polypropylene polyol, polybutadiene pol Examples include Rior. It is suitable that the molecular weight of these polyols is in the range of 100 to 5,000, preferably 500 to 4,000, and the addition amount of the polyol is preferably 40% by weight or less, particularly 30% by weight based on the lactam. The following is preferable. Copolymerization of a polyol is preferably used especially for enhancing impact resistance, but the idea of the present invention is determined by the requirements of the reinforcing material, the catalyst and the activator regardless of the presence or absence of the polyol.

The (B) catalyst used in the present invention is an alkali metal, alkaline earth metal, hydride, hydroxide, oxide, carbonate, alkoxy compound, alkyl compound, aryl compound, Grignard reagent, aluminum compound or the like of these metals. It is at least one compound selected from salts of metals and lactams, and particularly preferable metals are lithium, sodium, potassium, magnesium, calcium and aluminum. Among them, specific examples of the catalyst particularly useful in the present invention include lithium hydride, methyllithium,
n-butyllithium, lithium methoxide, sodium, sodium hydride, sodium methoxide, sodium ethoxide, sodium hydroxide, sodium carbonate,
Sodium lactamate, potassium, potassium hydride,
Potassium methoxide, potassium ethoxide, potassium hydroxide, potassium carbonate, potassium lactamate, calcium hydroxide, ethyl magnesium bromide, butyl magnesium bromide, propyl magnesium bromide, phenyl magnesium bromide, ethyl magnesium chloride, propyl magnesium chloride, butyl magnesium chloride , Phenylmagnesium chloride and reaction products of these Grignard reagents with ε-caprolactam, triethylaluminum, diethylchloroaluminum, ethyldichloroaluminum, aluminum propoxide and reaction products of ε-caprolactam with these aluminum compounds. it can. The amount of the catalyst added needs to be within the range of 0.1 to 3 mol% with respect to ε-caprolactam, and is more preferably within the range of 0.3 to 2.5 mol%. If the amount of the catalyst added is less than 0.1 mol%, the polymerization activity will be extremely reduced, which is not preferable. On the other hand, if the amount of the catalyst exceeds 3 mol%, the amount of metal ions remaining in the poly ε-caprolactam molded product will increase. However, since this is coordinated to the amide group, adverse effects such as a decrease in the crystallinity of poly ε-caprolactam appear, which is not preferable.

The activator (C) used in the present invention is reacted with an acyllactam compound and ε-caprolactam containing at least one structural unit in which a hydrogen atom on the nitrogen atom of ε-caprolactam is substituted with a carbonyl group in the molecule. It is a compound for purifying the above acyllactam compound. Acyllactam compounds are roughly classified into those in which an acyllactam unit is directly connected to a carbon atom and those in which an acyllactam unit is directly connected to a hetero atom. Examples of the former include acetylcaprolactam, adipoylbiscaprolactam, sebacoylbiscaprolactam, terephthaloylbiscaprolactam, 2-chloroterephthaloylbiscaprolactam, 2,5-dichloroterephthaloylbiscaprolactam, isophthaloylbiscaprolactam. , Dibenzoylbiscaprolactam and the like, and the precursors of these acyllactam compounds include corresponding carboxylic acids and halides thereof.

On the other hand, examples of the latter include hexamethylene-1,6-biscarbamidocaprolactam and tolylene-2,4 (2,6) -biscarbamidocaprolactam.
As its precursor, hexamethylene diisocyanate,
Examples include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, and the like.

The amount of activator added is 0.01 with respect to ε-caprolactam.
It is necessary to be in the range of 5 to 5 mol%, preferably 0.05 to 4.0 mol%. The amount of activator added is 0.1
When it is less than 5 mol%, the polymerization rate and the polymerization rate are remarkably lowered, which is not preferable, and when the addition amount exceeds 5 mol%, the polymerization degree of the polymerized molded product to be produced is lowered to obtain a molded product having sufficient characteristics. I can't.

Examples of the (D) fibrous inorganic reinforcing material used in the present invention include glass fiber, carbon fiber, asbestos fiber, brass fiber, stainless fiber, etc., preferably chopped strand or milled fiber is used. You can In addition to these, potassium whisker titanate and the like can also be used, and these reinforcing materials can be used alone or in the form of a mixture.

Examples of the (E) isotropic non-fibrous inorganic filler used in the present invention include calcium carbonate, wollastonite, silica, glass beads, magnesium oxide, hollow glass balloons,
Examples include shirasu glass balloons, and these fillers can be used alone or as a mixture.

The addition amount of the fibrous inorganic reinforcing material and the isotropic non-fibrous inorganic filler must be 5 to 35% by weight and 15 to 60% by weight, respectively, and the total amount of both is 30 to 70% by weight.

Here, it is important to use the reinforcing material and the filler within the above specific range. Because the effect of the reinforcing material and the filler are different, the reinforcing material has a large thickening effect of the lactam composition,
It is also effective for improving the strength and rigidity of the molded product, but due to the anisotropy, it causes disproportionate dimensional change of the molded product and warps easily.

On the other hand, the filler is more isotropic than the reinforcing material in the thickening action of the lactam composition and the action of improving the strength and rigidity of the molded product, but it is possible to suppress the unbalanced dimensional change of the molded product.

Therefore, a lactam composition having suitable flowability and operability of the lactam composition stock solution can be obtained only by selecting the amounts of the reinforcing material and the filler to be added and using them in combination within the above-specified specific range. By subjecting a product to reaction injection molding, a molded product free of defects such as voids, excellent in strength, rigidity, heat resistance, impact resistance, and dimensional stability can be obtained. If the addition amount of the fibrous inorganic reinforcing material is less than 5% by weight, the viscosity of the lactam composition is too low, which causes air bubbles to be mixed, and the strength and rigidity of the molded product are insufficient, which is not preferable. Is more than 35% by weight, the viscosity of the lactam composition becomes too high, which makes smooth transfer difficult, which is not preferable.
If the addition amount of the non-fibrous inorganic filler is less than 15% by weight, the effect of suppressing the unbalanced dimensional change of the molded product is insufficient, which is not preferable, and if the addition amount exceeds 60% by weight, the viscosity of the lactam composition is increased. Is too high, which is not preferable.

A lactam composition prepared by mixing a lactam, a catalyst, an activator, a fibrous inorganic reinforcing material and an isotropic non-fibrous inorganic filler in a specific ratio as described above is injected into a mold preheated to 100 to 200 ° C. Then, a molded product is obtained by polymerizing for 0.5 to 30 minutes. Here, a preferred example of the method for producing a polymerized molded article will be described by taking RIM molding as an example, but the molding apparatus and system are not limited to this. FIG. 1 shows an example of a suitable molding apparatus. Tank 1 in Fig. 1
Is liquid I consisting of lactam, catalyst, fibrous inorganic reinforcing material and isotropic non-fibrous inorganic filler, and tank 2 is composed of lactam, activator, fibrous inorganic reinforcing material and isotropic non-fibrous inorganic filler. Liquid II is stored at 80-150 ℃. The liquids I and II are sent to the mixing chamber 5 by the measuring pumps 3 and 4, respectively, and are mixed there. Then, the liquid is heated to 100 to 200 ° C., preferably 120 to 180 ° C. It is poured in and the polymerization reaction is carried out for 0.5 to 30 minutes. After completion of the polymerization reaction, the mold may be opened and the molded product may be taken out.

The resin molded product of the present invention contains other components such as a pigment, a dye, a heat-resistant agent, an antioxidant, a weathering agent and a release agent as long as the fluidity, operability, polymerizability and physical properties of the polymerized molded product are not impaired. A flame retardant, a fluidity improver, a foaming agent, an antistatic agent, etc. can be added and introduced.

<Example> Hereinafter, the present invention will be described in more detail with reference to Examples. The properties described in the following examples were measured by the following methods.

(1) Undiluted solution viscosity: B type viscometer was used.

(2) Void in molded product: A molded product and a cross section obtained by cutting the central part of the molded product were observed under a microscope.

(3) Tensile properties: ASTM D638 (4) Bending properties: ASTM D790 (5) Izod impact strength: ASTM D256 (6) Heat distortion temperature: ASTM D648 (7) Molding shrinkage: Molding when JIS No. 1 dumbbell pieces are molded The length of the piece was compared with the original size of the mold.

(8) Warp: A rectangular plate having a length of 80 mm, a width of 80 mm, and a thickness of 3 mm was molded, and the deformation of the molded piece was visually observed.

Example 1 55% by weight of ε-caprolactam containing 2.5% of bromomagnesium caprolactamate based on lactam, milled glass fiber (MF-T10 manufactured by Asahi Fiber Glass Co., Ltd.)
15% by weight and glass beads (Toshiba Ballotini Co., Ltd.)
GB731A manufactured by K.K., a lactam composition consisting of 30% by weight is used as liquid I, and 55% by weight of ε-caprolactam containing 2.0 mol% of adipoylbiscaprolactam with respect to the lactam, 15% by weight of milled glass fiber and 30% by weight of glass beads. Was prepared as a liquid II.

The viscosities of solutions I and II are as shown in Table 1, and it was found that the solutions I and II have viscosities suitable for liquid transfer operation and the like.

Liquid I was charged in tank 1 and liquid II in tank 2, and each was kept at 100 ° C. Next, the equivalent amounts of liquid I and liquid II were sent to a mixing chamber by a metering pump and mixed, and the mixed liquid was preheated to 170 ° C.
Polymerization was carried out by injecting into a mold which had been heated. After 10 minutes, the mold was opened and the molded product was taken out. As a result, the molded product had a good surface appearance and was excellent without voids.

The physical properties of the molded product are as shown in Table 1, and it was found that this product has excellent strength, rigidity, and heat resistance and has extremely high practical value.

Comparative Example 1 Reaction injection molding was performed in exactly the same manner as in Example 1 except that the added amounts of milled glass fiber and glass beads were 2% by weight and 43% by weight, respectively. The viscosity of the raw material liquid is shown in Table 1. As such, air bubbles that were considered to have been mixed in during the liquid transfer remained as voids in the obtained molded product, and the physical properties were low, and a good molded product could not be obtained.

Comparative Example 2 When the weighing, mixing and molding were performed in the same manner as in Example 1 except that the added amounts of milled glass fiber and glass beads were 40% by weight and 5% by weight, respectively, the undiluted solution viscosity was as shown in Table 1. Since it is too high, smooth metering and liquid transfer cannot be performed, and stable polymerization and molding cannot be performed due to changes in the composition of the molded product or fluctuations in the polymerization time. No molded product was obtained.

Examples 2 to 7 A lactam composition in which the types and amounts of the catalyst, activator, fibrous inorganic reinforcing material and non-fibrous inorganic filler were changed was subjected to reaction injection molding in the same procedure as in Example 1. As the results are shown in Table 1, the viscosity of the undiluted solution was at an appropriate level in terms of operation, and none of the obtained molded products had voids and had good strength, rigidity, impact resistance, heat resistance and dimensional stability. It was excellent.

<Effects of the Invention> As described above, the lactam composition obtained by highly selecting and specializing the type and addition amount of the catalyst, activator, fibrous inorganic reinforcing material and isotropic non-fibrous inorganic filler is specified. When anion polymerization molding of lactam, especially RIM type
It was found to have operability, and by subjecting this lactam composition to reaction injection molding, it became possible to obtain a molded product having no internal defects such as voids and excellent in strength, rigidity and heat resistance.

[Brief description of drawings]

 Figure 1 is a model of the RIM reaction injection molding machine. 1 …… I solution storage tank 2 …… II solution storage tank 3 …… I solution metering pump 4 …… II solution metering pump 5 …… Mixing chamber (mixing head) 6 …… Mold

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C08K 3/26 KKR 3/34 KKT 7/04 7/20 7/24

Claims (1)

[Claims] 1. A substantially anhydrous lactam (A may contain a polyol if necessary), and (B) 0.1 to 3 mol% of at least one catalyst selected from the following (I) with respect to the lactam. And / or (C)
A total of 30 to 70% by weight of 0.01 to 5 mol% of at least one activator selected from the following (II) with respect to lactam:
(D) 5 to 35% by weight of fibrous inorganic reinforcing material and (E) at least one isotropic non-fiber selected from calcium carbonate, wollastonite, silica, glass beads, magnesium oxide, hollow glass balloons and shirasu glass balloons Composition for reaction injection molding, which comprises 15 to 60% by weight of particulate inorganic filler. (I) Catalysts: alkali metals, alkaline earth metals, hydrides, hydroxides, oxides, carbonates, alkoxy compounds, alkyl compounds, aryl compounds, Grignard reagents, aluminum compounds and salts of these with lactams. II) Activator: acyllactam and a compound that can react with an lactam to form an acyllactam