JPH0554853B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a method for producing an amide resin foam molded product. More specifically, it relates to a method for producing amide-based resin casting foam molded products and reaction injection foam molded products. This invention relates to a method for producing molded products that improves the surface appearance by stabilizing the air bubbles generated by molding, suppressing the generation of voids on the surface of the molded product, and making the air bubbles in the molded product finer and more uniform. . "Prior art" In recent years, a method of injecting or injecting a highly reactive liquid raw material into a mold, polymerizing and molding it within the mold to directly obtain a molded product, the so-called reaction injection molding method or cast molding method, has been developed. Attention has been paid. Conventionally, polyurethane molded products have made great progress using the above molding method, but recently,
New materials such as polyamide resins, unsaturated polyester resins, and epoxy resins are also beginning to be used.
Among them, polyamide has excellent toughness, high rigidity, heat resistance, friction resistance, and wear properties. Furthermore, polyamide has good fluidity of the raw material composition and low heat generation during polymerization, so it is a low-performance material. It is particularly attracting attention as a material for reaction injection molding and cast molding because it can be molded under injection pressure, has good transferability on the mold surface, and can be used to produce molded products from thin to thick walls. ing. Taking advantage of these features of polyamide, we have further improved the mold filling properties, molded product sink marks, warpage, etc.
In order to reduce the weight of molded products, a method of foaming during molding has been proposed. As a method for obtaining a foamed molded article for the above purpose, there is a method described in JP-A-60-18332.
However, according to experiments conducted by the present inventors, when molding is carried out using this method, air bubbles can appear on the surface of the molded product, causing pinholes, voids, etc. on the surface of the molded product, or agglomeration of air bubbles. It has been found that there is a drawback that a molded product with a good surface appearance cannot be obtained because the internal bubbles become coarse and non-uniform. In addition, in reaction injection molding, cast molding, etc. of polyurethane, silicone surfactants, etc. are blended into the raw material composition, and the resulting foam regulating effect improves the surface appearance, miniaturization, and uniformity of internal bubbles. However, it has been found that these foaming agents are not sufficiently effective in reaction injection molding and cast molding of amide resins. The appearance of amide-based resin reaction injection molded products and cast molded products is characterized by being extremely good compared to, for example, reaction injection molded products or cast molded products such as polyurethane, and furthermore, the appearance of the reaction injection molded products and cast molded products of amide resins is extremely good. Even when post-processing, the appearance is finished well, so
It's a big advantage. Therefore, it has been desired to develop a method for producing foam molded products that maintains these excellent characteristics. "Problems to be Solved by the Invention" The present invention solves the problem of pinholes, voids, and air bubbles on the surface of the molded product when producing an amide resin foam molded product by reaction injection molding and cast molding. It is an object of the present invention to provide a method for obtaining a molded article in which agglomeration does not occur and the air bubbles inside the molded article are fine and uniform. ``Means for Solving the Problems'' The gist of the present invention is to produce a molten omega-lactam containing a polymerization catalyst, selected from the following group (), in the production of amide resin foam molded products. blending an aliphatic polyamide soluble in the ω-lactam melt with at least one of the ω-lactam melts containing one or more polymerization catalysts,
The present invention relates to a method for producing an amide-based resin foam molded product, which comprises injecting or injecting it into a mold to form a molded product. () group expression and [wherein A is halogen or (where Y is _C3 - _C11 alkylene),
a is an integer of 1, 2 or 3, b is an integer of 2 or more, and R ₁ is an alkyl group, an aralkyl group, an alkyloxy group, an aryloxy group, a halogen group, or an aralkyloxy group. , R ₂ is a divalent or higher group selected from hydrocarbon groups and hydrocarbons containing ether bonds, and Z is (1) a polyether having a minimum molecular weight of about 2000, (2) a minimum molecular weight of about 2000 or (3) a hydrocarbon having a minimum molecular weight of about 1000. Acid halide functional substance or acyllactam functional substance consisting of the following: The present invention will be described in detail. In amide resin reaction injection molding or cast molding, several types of raw materials used are prepared by dividing them into two or more component systems, and during molding, these raw material compositions divided into two or more component systems are The materials are combined by impingement mixing, static mixer, dynamic mixer, etc., and polymerization and molding are performed simultaneously in a mold. In amide resin reaction injection molding or cast molding, if it is a two-component system, one component system of the raw material composition (hereinafter referred to as component system A) is a polymerization catalyst and omega-lactam melt, and the other component system is Component system B (hereinafter referred to as component system B) consists of a polymerization cocatalyst, various additives and a melt of an ω-lactam. The aliphatic polyamides soluble in the omega-lactam melt used in the method of the present invention improve the uniformity of cells in foamed molded products, and prevent pinholes, voids, and agglomeration of cells on the surface of the molded product. The function is to prevent the occurrence of unevenness on the surface of the molded product due to this. However, as aliphatic polyamides soluble in a melt of ω-lactam, the following four monomer groups constituting polyamides are used: (a) dicarboxylic acids, (b) diamines, ( c) aminocarboxylic acids, (d)
Examples include copolymers composed of at least three types of monomer components selected from at least three types of lactams. (a) Dicarboxylic acids, which are one of the monomer groups, include adipic acid, sebacic acid, corkic acid, glutaric acid, azelaic acid, β-methyladipic acid,
Examples include decamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid, 1,10-decanedicarboxylic acid, and pimelic acid. Among this group (a), adivic acid and sebacic acid are preferred. (b) Diamines include ethylene diamine, tetramethylene diamine, hexamethylene diamine, octamethylene diamine, decamethylene diamine, metaxylene diamine, and baraxylene diamine. Among this group (b), hexamethylene diamine is preferred. Examples of the aminocarboxylic acids (c) as a monomer group include 6-aminocaproic acid, 7-aminoenanthic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 17-aminoheptadecanoic acid. (d) Lactams include ω-caprolactam,
Examples include enantlactam, caprylolactam, ω-undecanolactam, ω-laurinlactam, decyllactam, andecyllactam, and the like. Among the four groups (a) to (d) above, the copolymer composed of at least three types of monomer components selected from at least three groups is a known copolymer for producing aliphatic polyamides. It can be easily manufactured by this method. The polyamides used in the present invention can be added to either component system A or component system B, or can be added to both component system A and molding system B at the same time. Specific examples of the ω-lactam used in the present invention include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-capryllactam, ω-undecanolactam, and ω-laurinlactam. Can be mentioned.
These omega-lactams may be used alone,
Two or more types may be used. As the polymerization catalyst contained in component system A, any compound used in the known anionic polymerization of ω-lactams can be used. Specific examples include alkali metals, alkaline earth metals, their hydrides, oxides, hydroxides, carbonates, alkyl compounds, aryl compounds, alkoxides, Grignard compounds, and ω- Examples of reaction products with lactams include sodium salts, potassium salts, and magnesium halide salts of ω-lactams.
The amount of polymerization catalyst used is based on the total ω-lactam.
It ranges from 0.01 to 15, or 20% moles or more. Regarding the polymerization catalyst contained in component system B,
One or more compounds selected from the compounds included in the above group () are used. Component system B can contain a crosslinking agent, a modifier (soft segment), etc. that enter the polymer chain when reacting with component system A in the mold. These compounds include compounds having a polyvalent hydroxyl group, mercapto group, amino group or epoxy group. Examples of compounds having polyvalent hydroxyl groups include alkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, tetramethylene glycol, propylene glycol, dilopylene glycol, hexylene glycol, 1,2-propanediol, 1,
3-propanediol, 1,3-hexanediol, butylene glycol, 1,4-butanediol, dicyclopentadiene glycol, heptaethylene glycol and isopropylidene bath (P-phenyleneoxypropanol-2), other than alkylene glycol Polyols such as glycerol, pentaerythritol, 1,2,6-hexanetriol and 1-trimethylolpropane, polymeric polyols such as polyethylene glycol, polypropylene glycol, polyoxypropylene diol, and triols, polytetramethylene glycol, castor oil, polybutadiene glycol , polyester glycols, poly(ε-caprolactone) diols and a number of compounds containing substituents other than hydroxy groups such as 2,4-dichlorobutylene glycol. Examples of compounds having a polyvalent mercapto group include hydroxyethylthioglycolate, ethylene glycol bis(thioglycolate), pentaerythritol tetrakis(thioglycolate), and thioglycol, which have a polyvalent amino group. Compounds include hexamethylene diamine, tolylene diamine, 2,4-diethyl tolylene diamine, polyoxyethylene diamine,
Polyoxypropylene diamines and triamines, polyoxypropylene amines, copolyamides with amino terminal groups, etc., and compounds having polyvalent epoxy groups include resorcinol diglycidyl ether, diglycidyl ether of bisphenol A, vinyl cyclohexane dioxide, butanediol diglycidyl ether, polyglycidyl ester of polycarboxylic acid,
Examples include epoxidized polyolefin and glycidyl ether resins, and epoxy novolac resins. Component system B may further contain compounds that do not substantially inhibit the polymerization reaction, such as plasticizers, dyes and pigments, antioxidants, internal mold release agents, and the like. Next, to describe the method for manufacturing amide resin molded articles according to the present invention, first, a polymerization catalyst is added to ω-lactam, and the melting point of ω-lactam or higher (for example, ω
- If the lactam is caprolactam, heat to 70°C or higher) to make a melt of component system A. This melt of component system A is maintained at a temperature below 100° C. in order to inhibit the polymerization reaction itself. Similarly, component system B is
By adding polymerization promoters, additives, etc. to ω-lactam, ω-
A molten substance is created by heating the lactam above its melting point and keeping it below 140°C. Next, add 2 to the above adjustment component system.
The total amount of aliphatic polyamides specified in the present invention in the required amount with respect to the total amount of component-based polyamide components,
Only in either component system A or component system B,
Or, part of it is in component system A or component system B, and the rest is in component system B or component system A, or
Mix evenly into component system A and component system B. The above distribution mixing of the aliphatic polyamides is determined each time depending on the viscosity of component system A or component system B, the type of ω-lactam, etc. In the method of the present invention, a blowing agent is added to the raw material composition. The blowing agents used in the method of the present invention include nitrogen gas, dry air, inert gases such as argon and helium, and low-boiling organic compounds such as heptane, pentane, hexane, cyclohexane and benzene. In order to add these blowing agents to the raw material composition, when the blowing agent is an inert gas, it is added to one or both of component system A and component system B in a tank.
A method of dissolving or dispersing is preferable. When the blowing agent is a low-boiling organic compound, it is preferably dissolved in one or both of component system A and component system B in a tank. The amount of the blowing agent to be dissolved or dispersed in the raw material composition can be changed depending on the purpose of the molded article to be manufactured, the properties to be provided, the type of blowing agent used, the porosity of the molded article, etc. What is the porosity of a molded product?
This refers to the volume ratio of fine bubbles formed in a molded product by a blowing agent to the molded product. The porosity of the molded product is preferably in the range of 0.1 to 90%. When the porosity is 0.1% or less, there are few bubbles generated in the molded product, so problems such as pinholes, voids, and bubble aggregation do not occur on the surface of the molded product. If the porosity is 90% or more, too many air bubbles will be generated in the molded product, making it difficult to achieve the object of the invention, which is not preferable. The following procedure is used to produce a foamed molded article from the amide resin molding composition in which the blowing agent prepared as above is dissolved or dispersed. First, component system A and component system B molten slurries are rapidly mixed and injected or poured into a mold. 2
The components may be mixed, for example, by collision mixing in a device called a mixing head, or by stirring with a static mixer, dynamic mixer, or the like. The mixing ratio of component system A and component system B can be changed depending on the use and properties of the molded product to be manufactured. The mixing ratio in this case is preferably in the range of 5/1 to 1/5 by volume. The mold temperature during molding is preferably maintained in the range of 100 to 200°C, preferably 120 to 160°C. In the mold, a chemical reaction occurs between component system A and component system B, and within a short time after injection into the mold, within 4 minutes, sometimes within 2 minutes, depending on the size of the molded product. Hardens or solidifies, completing a chemical reaction. After the chemical reaction is complete, the molded product is removed from the mold. "Effects of the Invention" The present invention has been described above, and has particularly remarkable effects as described below, and its industrial utility value is extremely large. (1) When using the method of the present invention, a soluble aliphatic polyamide is blended into the ω-lactam melt as a raw material, and the ω-lactam melt blended with this has good fluidity; Since it is stable, it is easy to handle and also easy to inject into a mold during molding. (2) When using the method of the present invention, the aliphatic polyamide blended into the omega-lactam melt improves the uniformity of the cells in the foam molded product and prevents pinholes, voids, and bubble aggregation on the surface of the molded product. Since it functions to suppress the resulting unevenness on the surface of the molded product, a foamed molded product with an excellent appearance can be obtained. (3) The foam molded product obtained by the method of the present invention is
Since the cells are fine and uniform, the foam molded product has excellent mechanical properties such as tensile strength. "Examples" Next, the present invention will be explained with reference to Examples and Comparative Examples.
It is not limited to the following examples. The polyamides soluble in the ω-lactam melt used in the following examples are as follows.
In addition, evaluation of the appearance of the obtained molded product and measurement of the average cell diameter, porosity, bending rigidity, tensile strength, elongation, etc. of the molded product were carried out in accordance with the following methods. Nylon: - A copolymer containing five monomer components: ω-caprolactam, hexamethylene diamine, adipic acid, sebacic acid, and lauryllactam. When expressed as a polyamide, nylon 6: nylon
66: Nylon 610: Nylon 612 composition ratio is 5:
45:45:5 and its average molecular weight is approximately 70,000. Nylon: - It is a copolymer containing four monomer components of ω-caprolactam, hexethylene diamine, adipic acid, and lauryllactam, and when expressed as a polyamide, it is nylon 6: nylon 66: nylon.
The composition ratio of 12 is 2:2:3 and the average molecular weight is approximately 80,000. Appearance of molded product: - Mainly by visual observation, but optionally supplemented by surface roughness tester (Model SE-3A manufactured by Kosaka Laboratory)
It was evaluated using The display criteria for the results were 4 levels: ◎: best, ○: good, △: fair, and ×: poor. Measurement of porosity of molded products: - Cut out a dry test piece from the molded product, and
The specific gravity was measured according to K-6911 and calculated using the following formula. Porosity (%) = (Specific gravity of non-foamed resin) - (Specific gravity of sample) / Specific gravity of non-foamed resin x 100 Measurement of average cell diameter in a molded product: - Cut a thin section from any cross section of the molded product. The diameter of the bubbles was measured using a cut-out optical microscope, and was taken as the number average diameter of the bubbles. Measurement of bending rigidity of molded product: - A dry test piece was cut out from the flat molded product and measured in accordance with ASTM D-790. Measurement of tensile strength and elongation of molded product: - Dry test pieces were cut out from flat molded products and measured in accordance with JIS K-7113. Example 1 The following component system A and component system B were each prepared in a component system holding tank, and each tank was sealed with nitrogen gas at 2 kg/cm ² ·f while stirring while maintaining the temperature at 90°C. Component system A ε-caprolactam 40.1Kg Bromomagnesium caprolactam 2.4〃 Nylon 2.1〃 Component B ε-caprolactam 23.5Kg Polymerization cocatalyst (X) 19.0〃 Nylon 1.2〃 The polymerization cocatalyst (X) added to component system B is as follows. formula (However, in the formula, Z represents a block copolymer of ethylene oxide and propylene oxide with a molecular weight of about 6,000.) Next, component system A and component system B were mixed by collision using a reaction injection molding machine, and injected into a sheet mold having a chiar bit of 500 mm in length and width and 3 mm in depth, temperature controlled at 140°C. hold for 2 minutes,
A foam molded product was obtained. Table 1 shows the results of measuring the physical properties of this foam molded product. Comparative Example 1 Component system A and component system B were prepared in the same manner as in Example 1, except that nylon was not used. A foam molded article was obtained from these two components by the same reaction injection molding method as in the same example. Table 1 shows the results of measuring the physical properties of this foam molded product. Example 2 The following component system A and component system B were each prepared in a component system holding tank, and each tank was sealed with nitrogen gas at 2 kg/cm ² ·f while stirring while maintaining the temperature at 90°C. Component system A ε-caprolactam 33.0Kg Bromomagnesium caprolactam 2.0〃 Nylon 1.7〃 Component B ε-caprolactam 19.4Kg Polymerization cocatalyst (y) 15.6〃 Milled glass (a) 1.7〃 Polymerization cocatalyst added to component system B (y ) is the following formula (However, Z represents polybutadiene with a molecular weight of approximately 6000.) Milled glass (a) has a fiber diameter of 11 μm, a weight average fiber length of 75 μm, and a fiber length of 25 μm.
The fiber length is less than 5% by weight, and the fiber length of more than 300 μm is 7% by weight, and the surface is treated with γ-aminopropyltriethoxysilane. A foam molded article was obtained using the above two components in the same manner as described in Example 1 using a reaction injection molding machine.
The results of measuring the physical properties of this foam molded product are
Shown in Table 1. Comparative Example 2 The same procedure as in Example 2 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 3 In the example described in Example 2, milled glass (a)
The procedure was the same as in the same example except that glass flakes having the following properties were used instead of. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Glass flakes range in diameter from 90 to 150 μm,
The aspect ratio is 50. Comparative Example 3 The same procedure as in Example 3 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 4 Component system A and component system B were prepared in the same manner as in Example 2, except that nylon was replaced with nylon. A foamed injection molded article was obtained from these two components by the same reaction injection molding method as in the same example. Table 1 shows the results of measuring the physical properties of this foam molded product. Example 5 Component system A and component system B were prepared in the same manner as in Example 2, except that nylon was replaced with nylon. A foamed injection molded article was obtained from these two components by the same reaction injection molding method as in the same example. Table 1 shows the results of measuring the physical properties of this foam molded product. Example 6 The same procedure was used as in Example 1 except that the pressure of the nitrogen gas that sealed each component tank was 0.8 Kg/cm ² ·f. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Comparative Example 4 The same procedure as in Example 6 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 7 The example described in Example 2 was the same as in Example 2 except that the pressure of the nitrogen gas that sealed each component tank was 0.8 Kg/cm ² ·f. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Comparative Example 5 The same procedure as in Example 7 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 8 The same procedure as in Example 1 was carried out except that the pressure of the nitrogen gas that sealed each component tank was 5 kg/cm ² ·f. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Comparative Example 6 The same procedure as in Example 8 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 9 The example described in Example 2 was the same as in Example 2 except that the pressure of the nitrogen gas that sealed each component tank was 5 kg/cm ² ·f. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Comparative Example 7 The same procedure as in Example 9 was carried out except that nylon was not used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained.

[Table] From Table 1, it can be seen that the amide resin foam molded product obtained by the method of the present invention has a superior appearance and tensile strength compared to the foam molded product obtained by the method of the comparative example. , elongation, etc. are also found to be excellent.

Claims (1)

[Scope of Claims] 1. In producing an amide resin foam molded article, an omega-lactam melt containing a polymerization catalyst, an omega-lactam melt containing one or more polymerization co-catalysts selected from the following group (2): At least one of the shaped objects,
A method for producing an amide resin foam molded article, which comprises blending an omega-lactam with a soluble aliphatic polyamide and injecting or injecting the mixture into a mold to form a molded article. () group expression and [wherein A is halogen or (wherein Y is C ₃ -C ₁₁ alkylene), a is an integer of 1, 2 or 3, b is an integer of 2 or more, R ₁ is an alkyl group,
is an aralkyl group, an alkyloxy group, an aryloxy group, a halogen group, or an aralkyloxy group, R ₂ is a divalent or higher group selected from a hydrocarbon group and a hydrocarbon containing an ether bond, and Z is (1) a polyether having a minimum molecular weight of about 2000, (2) a polyester segment containing a polyether segment having a minimum molecular weight of about 2000, or (3) a hydrocarbon having a minimum molecular weight of about 1000. ] An acid halide functional substance or an acyllactam functional substance. 2. Aliphatic polyamides that are soluble in a melt of ω-lactam contain the following four monomer groups that constitute aliphatic polyamides: (a) aliphatic dicarboxylic acids (b) diamines ( c) aminocarboxylic acids (d) at least three selected from the group of at least three lactams
The method for producing an amide resin foam molded article according to claim 1, wherein the copolymer is a copolymer composed of different types of monomer components. 3. Claims characterized in that the amount of the aliphatic polyamide soluble in the omega-lactam melt ranges from 0.1 to 30 parts by weight per 100 parts by weight of the total raw material composition. A method for producing an amide resin foam molded product according to items 1 and 2. 4. The method according to any one of claims 1 to 3, characterized in that a crosslinking agent or a reaction product modifier is blended into the omega-lactam melt containing the polymerization cocatalyst. A method for producing an amide resin foam molded product. 5. Claims 1 to 4, characterized in that an inert gas is dissolved or dispersed in the raw material composition, or a low boiling point organic compound is dissolved therein.
A method for producing an amide resin foam molded product according to any one of the above items. 6 The porosity of the amide resin foam molded product is 0.1~
The method for producing an amide resin foam molded product according to any one of claims 1 to 4, characterized in that the amide resin foam molded product is in a range of 90%. 7. The amide resin foam molding according to any one of claims 1 to 5, characterized in that a filler such as glass fiber, glass flakes, or glass beads is blended into the raw material composition. method of manufacturing the product. 8. Production of an amide-based resin foam molded product according to claim 7, characterized in that the amount of filler blended is in the range of 1 to 50 parts by weight per 100 parts by weight of the total amount of the raw material composition. Method.