JPH0525254B2 - - 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 resin foam molded products and reaction injection foam molded products, in which the molding operation is easy during molding, the obtained molded products have good mechanical properties,
This relates to a method for producing a molded product that improves the surface appearance by stabilizing the air bubbles generated by foaming, 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 casting molding method. is attracting attention. Conventionally, polyurethane molded products have made great progress using the above molding method, but recently,
New materials such as polyamides, unsaturated polyesters, and epoxies are also beginning to be used. Among them, polyamide has excellent toughness, high rigidity, heat resistance, and good friction resistance and wear characteristics. Furthermore, polyamide has good fluidity of the raw material composition and low heat generation during polymerization, so it has a low injection rate. It is attracting particular attention as a material for reaction injection molding and injection molding because it can be molded under pressure, has good transferability on the mold surface, and can be used to produce molded products of any thickness from thin to thick. There is. 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 that meets 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 performed using this method, air bubbles appear on the surface of the molded product, creating pinholes, voids, etc. on the surface of the molded product, and causing agglomeration of air bubbles. occurs, and the internal bubbles become coarser.
It has been found that there is a drawback that non-uniformity occurs and a molded product with a good surface appearance cannot be obtained. In addition, in reaction injection molding, casting molding, etc. of polyurethane, silicone surfactants, etc. are blended into the raw material composition, and the resulting foam regulating effect improves the surface appearance and the miniaturization and uniformity of internal bubbles. However, in reaction injection molding and injection molding of amide resins,
It was found that these foam stabilizers were also insufficiently effective. 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 such as polyurethane, or cast molded products, and even better when painted. 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 casting molding. It is an object of the present invention to provide a method for obtaining a molded article in which no agglomeration occurs and the air bubbles inside the molded article are fine and uniform. "Means for Solving the Problems" The gist of the present invention is that, in producing amide resin foam molded products, a melt of omega-lactam containing a polymerization catalyst, an omega-lactam containing a polymerization co-catalyst, etc. - at least one side of the lactam melt, ω
- A method for manufacturing an amide resin foam molded article, which comprises blending a molten lactam with a soluble styrene resin and injecting or injecting the mixture into a mold to obtain a molded article. The present invention will be explained in detail below. In amide resin reaction injection molding or injection molding, several types of raw materials used are prepared separately into two or more component systems, and during molding, these raw material compositions divided into two or more component systems are , collisional mixing, static mixer, dynamic mixer, etc., and polymerization and molding are performed simultaneously in a mold. In amide resin reaction injection molding or injection molding, one component system (hereinafter referred to as component system (A)) of a two-component raw material composition is a polymerization catalyst and a melt of an ω-lactam, and the other component is a polymerization catalyst and an ω-lactam melt. The system (referred to as component system (B)) consists of a polymerization cocatalyst, various additives, and a melt of ω-lactam. The styrenic resin that is soluble in the omega-lactam melt used in the method of the present invention improves the uniformity of the cells in the foamed molded product and prevents pinholes, voids, and bubbles from agglomerating on the surface of the molded product. It functions to prevent unevenness, etc. from occurring on the surface of the molded product. Examples of styrene resins that are soluble in the ω-lactam melt include polystyrene, rubber-reinforced polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene block copolymer, styrene-ethylene block copolymer, and styrene-acrylonitrile copolymer.
Examples include propylene block copolymers, styrene-ethylene-diene monomer block copolymers, and styrene-isoprene block copolymers. These block copolymers preferably have a structure in which polystyrene blocks are located at the ends.
When using the above styrene resins, one type may be used, or two or more types may be combined. The above styrene resin 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 component system (B) at the same time. This is also possible. Specific examples of the ω-lactam used in the present invention include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-capryllactam, ω-undecanoetam, ω-laurinlactam, etc. can be mentioned.
These omega-lactams may be used alone,
Two or more types may be used in combination. 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 mol% or more. Regarding the polymerization catalyst contained in component system (B), ω
- Any compound known for use in anionic polymerization of lactams can be used. Specific examples thereof include isocyanates such as toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl polyisocyanate, diisocyanate modified with carbodiimide, hexamethylene-1,6- Biscarbamide, caprolactam, N,N'-diphenyl-
Carbamide lactams such as P-phenylenebiscarbamate caprolactam, N,N'-diphenyl-P-phenylenebiscarbamid, and pyrrolidone; acid halides such as terephthaloyl chloride, adipic acid chloride, and sebacic acid chloride. ,
Adipoyl biscaprolactam, adipoyl bispyrrolidone terephthaloyl biscaprolactam,
Polyacyllactams such as terephthaloyl bispyrrolidone, or formula

【formula】

【formula】

【formula】

【formula】 and

[Formula] [In the formula, A is halo Gen or

[Formula] (where Y is C ₃ - C ₁₁ alkylene) and a is 1, 2
or an integer of 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 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 1000. Examples include acid halide-functional materials or lactam-functional materials. The component system (B) can contain a crosslinking agent, a modifier (soft segment), etc. that enter the polymer chain when reacting with the 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, dipropylene glycol, hexylene glycol, 1,2-propanediol,
1,3-propanediol, 1,3-hexanediol, butylene glycol, 1,4-butanediol, dicyclopentadiene glycol, heptaethylene glycol and isopropylidene bis(P-phenyleneoxypropanol-2),
Polyols other than alkylene glycols such as glycerol, pentaerythritol, 1,2,6
- hexanetriol and 1-trimethylolpropane, polymeric polyols such as polyethylene glycol, polypropylene glycol, polyoxypropylene diol, and triols,
Mention may be made of polytetramethylene glycol, castor oil, polybutadiene glycol, polyester glycol, poly(ε-caprolactone) diol 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 thiodiglycol. Examples of the compounds include hexamethylene diamine, tolylene diamine, 2,4-diethyltolylene diamine, polyoxyethylene diamine, polyoxypropylene diamine and triamine, polyoxypropylene diamine, and copolymerized polyamides with amino terminal groups. Examples of compounds having polyvalent epoxy groups include resorcinol dicrycidyl ether, diglycidyl ether of bisphenol A, vinylcyclohexane dioxide, butanediol diglycidyl ether, polyglycidyl ester of polycarboxylic acid, epoxidized polyolefin, and glycidyl ether of bisphenol A. Examples include cidyl ether resin and epoxy novolac resin. The component system (B) may further contain compounds that do not substantially inhibit the polymerization reaction, such as plasticizers, dyes, 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-lactam is
If the lactam is caprolactam, heat to 70℃ or higher) to create a melt of component system (A). This melt of component system (A) is used to inhibit the polymerization reaction by itself.
Maintained below 100℃. Similarly, the component system (B) is ω
- A polymerization promoter, additives, etc. are added to the lactam, heated above the melting point of the ω-lactam, and kept at 140°C or below to form a molten product. Next, the total amount of styrene resin specified in the present invention, which is the required amount for the total amount of the two-component polyamide component, is added to the above preparation component system.
(A) or component system (B) only, or part of the component system (A) or component system (B) and the rest in component system (B) or component system (A), or , component system
Mix (A) and component system (B) evenly. The above distribution mixing of the styrene resin is determined each time depending on the viscosity of the 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-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, if the blowing agent is an inert gas, it is necessary to
(A), component system (B), or both in the tank.
A method of dissolving or dispersing is preferable. If the blowing agent is a low boiling point organic compound, component system (A), component system
It is best to dissolve one or both of (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. It is undesirable for the porosity to be 90% or more, since too many bubbles will be generated in the molded product, making it difficult to achieve the object of the invention. In order to produce a foamed molded article from the amide resin molding composition in which the blowing agent prepared as above is dissolved or dispersed, the following procedure is followed. 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 or dynamic mixer. The mixing ratio of the component system (A) and the 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 the component system (A) and the component system (B), and within a short time after injection into the mold, within 4 minutes depending on the size of the molded product, in some cases. It hardens or solidifies within 2 minutes, completing the 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 the following special and remarkable effects, and its industrial utility value is extremely large. (1) When using the method of the present invention, a soluble styrene resin is blended into the raw material ω-lactam melt, but the ω-lactam melt blended with this resin has good fluidity and is stable. , easy to handle, and easy to inject into a mold during molding. (2) When using the method of the present invention, the styrene resin blended into the omega-lactam melt improves the uniformity of the cells in the foamed molded product, causing pinholes, voids, and bubble aggregation on the surface of the molded product. Since it functions to suppress 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, but the present invention does not exceed the gist thereof.
It is not limited to the following examples. The styrenic resins 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, measurement of the bending rigidity of the molded product, tensile strength and elongation of the molded product, average cell diameter in the molded product, porosity of the molded product, etc.
I did it in the following way. Styrenic resin soluble in omega-lactam melt: Polymer: - A block copolymer with a styrene-butadiene ratio of 70:30, with polystyrene components at both ends of the molecular chain. The molecular weight measured by gel permeation chromatography (GPC) is approximately 100,000. Polymer: - Polystyrene (manufactured by Mitsubishi Monsanto Chemical Co., Ltd., general purpose polystyrene, trade name: Dialex HH)
-102) Appearance evaluation of molded products: - Mainly by visual observation, but in some cases, surface roughness meter (Model SE manufactured by Kosaka Laboratory)
3A). The display criteria for the results are:
There were four levels: ◎: best, ○: good, △: fair, and ×: poor. Measuring the porosity of a molded product: - Cut a dry test piece from the molded product,
Specific gravity was measured in accordance with JISK-6911 and calculated using the following formula. Porosity (%) = (specific gravity of unfoamed resin) - (specific gravity of sample)
/Specific gravity of non-foamed resin x 100 Measurement of average cell diameter in molded product: - A thin section was cut from any cross section of the molded product, the foamability was measured using an optical microscope, and the number average was taken as the average cell diameter. 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 was sealed with 2 kg/cm ² of nitrogen gas while stirring while maintaining the temperature at 90°C. did. Component system (A) ε-caprolactam 46.9Kg Sodium pyrrolidone 0.7〃 Polymer 2.5〃 Component system (B) ε-Caprolactam 26.9Kg Terephthaloyl biscaprolactam 3.9〃 Polypropylene glycol (molecular weight 2000) 19.3〃 Polymer 1.4〃 Next, the components System (A) and component system (B) were mixed by collision using a reaction injection molding machine, and injected into a sheet mold having a cavity 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 the example described in Example 1, except that no polymer was used. A foam molded article was obtained from these two components by the same reaction injection molding method as in the same column. 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 was heated with nitrogen gas at 2 kg/cm ² f while stirring while maintaining the temperature at 90°C. I sealed it. Component system (A) ε-caprolactam 40.1Kg Bromomagnesium caprolactam 2.4〃 Polymer 2.1〃 Component system (B) ε-caprolactam 23.5Kg Polymerization co-catalyst (X) 19.3〃 Polymer 1.2〃 Polymerization co-catalyst added to component system (B) The catalyst (X) is the following 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, the above two components were treated in the same manner as described in Example 1 to obtain a foam molded product using a reaction injection molding machine. Table 1 shows the results of measuring the physical properties of this foam molded product. Comparative Example 2 Component system (A) and component system (B) were prepared in the same manner as in Comparative Example 2, except that no polymer was used. A foam molded article was obtained from these two components by the same reaction injection molding method as in the same column. Table 1 shows the results of measuring the physical properties of this foam molded product. Example 3 The following component system (A) and component system (B) were each prepared in a component system holding tank, and each was heated with nitrogen gas at 2 kg/cm ² ·f while stirring while maintaining the temperature at 90°C. I sealed it. Component system (A) ε-caprolactam 33.0Kg Bromomagnesium caprolactam 2.0〃 Polymer 1.7〃 Component system (B) ε-caprolactam 19.4Kg Polymerization promoter (y) 15.6〃 Milled glass (a) 1.7〃 Added to component system (B) The weight cocatalyst (y) obtained is expressed by 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 3 The same procedure as in Example 3 was repeated except that no polymer was used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 4 In the example described in Example 3, 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 4 The example described in Example 4 was repeated except that no polymer was used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 5 Component system (A) and component system (B) were prepared in the same manner as in Example 2, except that the polymer was replaced with a polymer. 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 Component system (A) and component system (B) were prepared in the same manner as in Example 3, except that the polymer was replaced with a polymer. 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 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 example described in Example 7 was repeated except that no polymer was 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 3 was carried out, 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 6 The same procedure as in Example 8 was repeated except that no polymer was used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 9 The same procedure as in Example 2 was carried out except that the pressure of the nitrogen gas that sealed each component tank was set to 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 example described in Example 9 was repeated except that no polymer was used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Example 10 The same procedure as in Example 3 was carried out except that the pressure of the nitrogen gas that sealed each component tank was set to 5 kg/cm ² ·f. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained. Comparative Example 8 The same procedure as in Example 10 was repeated except that no polymer was used. Table 1 shows the results of measuring the physical properties of the foamed molded product obtained.

[Table] Table 1 shows that the amide resin foam molded products obtained by the method of the present invention have superior appearance and tensile strength compared to the foam molded products obtained by the comparative method. It is clear that the strength and elongation are also excellent.

Claims (1)

[Scope of Claims] 1. In producing an amide resin foam molded product, ω-lactam is added to at least one of the ω-lactam melt containing a polymerization catalyst and the ω-lactam melt containing a polymerization co-catalyst. A method for producing an amide resin foam molded product, which comprises blending a molten lactam with a soluble styrene resin and injecting or injecting the mixture into a mold to form a molded product. 2 Styrenic resins soluble in the ω-lactam melt include polystyrene, rubber-reinforced polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene block copolymer, styrene-ethylene block copolymer, and styrene-propylene block copolymer. The amide resin foam molding according to claim 1, which is selected from the group consisting of a styrene-ethylene-diene monomer block copolymer, and a styrene-isoprene block copolymer. method of manufacturing the product. 3. The amount of styrene resin soluble in the omega-lactam melt is determined per 100 parts by weight of the total raw material composition,
characterized by a range of 0.1 to 30 parts by weight,
A method for producing an amide resin foam molded article according to claims 1 and 2. 4. The foamed amide resin according to 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. Method of manufacturing molded products. 5. Claims 1 to 3, characterized in that an inert gas is dissolved or dispersed in the raw material composition, or a low boiling point organic compound is dissolved in the raw material composition.
A method for producing an amide-based resin foam molded product as described in 2. 6 The porosity of the amide resin foam molded product is 0.1~
A method for producing an amide resin foam molded product according to any one of claims 1 to 5, characterized in that the amide resin foam molded product is produced in a range of 90%. 7. A method for producing an amide resin foam molded article according to claims 1 to 5, characterized in that fillers such as glass fibers, glass flakes, and glass beads are blended into the raw material composition. 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.