JP2011256290A - Aromatic polyamide resin composition and its foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aromatic polyamide resin composition excellent in heat resistance and foaming property, and to provide a foam obtained by foaming the composition.SOLUTION: This aromatic polyamide resin composition contains an aromatic polyamide resin and a polyfunctional compound, and melt stress when measured at a temperature of (melting point of the resin composition +20)°C is 60 to 500 mN.

Description

  The present invention relates to an aromatic polyamide resin composition excellent in heat resistance and foamability and a foam obtained by foaming the same.

  Since aliphatic general-purpose polyamide resins represented by nylon 6 and nylon 66 have excellent properties such as heat resistance, chemical resistance, rigidity, slidability, and moldability, they are used in a wide range of applications. I came. However, in recent years, mainly in the automotive field, further improvement in heat resistance has been demanded, and while conventional aliphatic polyamide resins are becoming incapable of handling, demand for higher heat-resistant aromatic polyamide resins is increasing. Furthermore, demand for foams obtained by foaming an aromatic polyamide resin with a foaming agent is increasing in the fields of cushioning materials, packaging materials, building materials and the like, taking advantage of its light weight and cushioning properties.

  However, aromatic polyamide resins are inherently low in both melt viscosity and melt tension, and are therefore difficult to foam without modification. Therefore, the application of such an aromatic polyamide resin to a foam has been limited.

  In order to solve the above problems, there is known a method in which a crosslinking agent or a foaming agent is added, and the foaming agent is dissolved and foamed by extrusion while the polyamide resin is thickened in a single screw extruder. According to this method, a foam having an expansion ratio of up to 10 times can be obtained (for example, Patent Document 1). However, Patent Document 1 refers to an aliphatic polyamide resin having a melting point of less than 280 ° C., and all of the crosslinking agents used in such an aliphatic polyamide resin have a low molecular weight of substantially 1000 or less. A compound. Therefore, it has been difficult to react such a low molecular weight compound with a high melting point aromatic polyamide resin from the viewpoint of stability and volatility.

  In order to sufficiently thicken the aromatic polyamide resin, it is effective to use a twin-screw extruder to increase the temperature and melt-extrusion in a high shear state. However, in order to further increase the expansion ratio, it is necessary to lower the temperature near the outlet with a single-screw extruder and perform melt extrusion in a low shear state. That is, when extrusion foaming is performed in one stage while imparting foamability by thickening, there is a problem in the extrusion conditions. In particular, when an epoxy compound is used as a cross-linking agent, it takes time for the thickening reaction, so that it is substantially impossible to perform the thickening and extrusion foaming in one step.

  Further, in the injection foam molding of semi-aromatic polyamide resin, it is known to dissolve a supercritical fluid such as carbon dioxide or nitrogen as a foaming agent. In this case, a foam having an expansion ratio of up to 1.25 times can be obtained (for example, Patent Document 2). Further, it is known that a wholly aromatic polyamide resin dissolves an organic solvent and carbon dioxide. In this case, a foam having an expansion ratio of up to 3 times can be produced (for example, Patent Document 3). ).

  However, the foams obtained by the techniques disclosed in Patent Document 2 and Patent Document 3 have a problem that the expansion ratio is low and it is difficult to deploy to applications that require excellent lightness.

Japanese Patent Laid-Open No. 04-356541 JP 2005-132941 A JP 2003-301062 A

  The present invention solves the above-mentioned problems, can obtain a foam that can be used in applications that are foamed at a high magnification and require lightness, and is further excellent in heat resistance. An object of the present invention is to provide a polyamide resin composition and a foamed product comprising the aromatic polyamide resin composition.

  As a result of intensive studies to solve the above problems, the present inventors have obtained an aromatic polyamide resin composition obtained by reacting an aromatic polyamide resin and a polyfunctional compound, and (aromatic polyamide resin composition). Based on this finding, it is found that the melt tension measured at a temperature of the melting point of the product + 20 ° C. is in the range of 60 to 500 mN, so that the resin composition has excellent foamability and heat resistance. The present invention has been reached.

That is, the gist of the present invention is as follows.
(1) An aromatic polyamide resin composition comprising an aromatic polyamide resin and a polyfunctional compound, the melt tension when measured at (melting point of the aromatic polyamide resin composition + 20) ° C. is 60 to An aromatic polyamide resin composition, which is 500 mN.
(2) The polyfunctional compound is at least one selected from a polyfunctional epoxy compound, a polyfunctional isocyanate compound, a polyfunctional carbodiimide compound, a polyfunctional oxazoline compound, and a polyfunctional carboxylic anhydride (1) Aromatic polyamide resin composition.
(3) The aromatic polyamide resin content in the aromatic polyamide resin composition is 90 to 99.9% by mass, and the polyfunctional compound content is 0.1 to 10% by mass (1). Or aromatic polyamide resin composition of (2).
(4) A foam obtained by foaming the aromatic polyamide resin composition according to any one of (1) to (3).

  The aromatic polyamide resin composition of the present invention uses an aromatic polyamide resin as a main raw material, and can foam at a high magnification to obtain a foam excellent in lightness and heat resistance. In addition, the foam obtained from the aromatic polyamide resin composition of the present invention is excellent in heat resistance and lightweight, and can be used for various applications such as cushioning materials, packaging materials, and building materials.

Hereinafter, the present invention will be described in detail.
The aromatic polyamide resin composition of the present invention (hereinafter sometimes simply referred to as “resin composition”) contains an aromatic polyamide resin and a polyfunctional compound.

  The aromatic polyamide resin used in the present invention is a polyamide resin having an aromatic skeleton in a structural unit. In the present invention, heat resistance can be improved by using an aromatic polyamide resin as compared to the case of using another polyamide resin such as an aliphatic polyamide resin. Examples of the aromatic polyamide resin include polycondensates of aliphatic diamines having 4 to 12 carbon atoms and terephthalic acid and / or isophthalic acid, such as polyamide 6T, polyamide 6I, polyamide 6T / 6I, and polyamide 9T; polyamide Polycondensates of aliphatic diamines having 4 to 12 carbon atoms and aliphatic dicarboxylic acids having 4 to 12 carbon atoms with terephthalic acid and / or isophthalic acid, such as 6T / 66; carbon such as polyamide 6T / 6 And polycondensates of aliphatic aminocarboxylic acids having 4 to 12 carbon atoms, aliphatic diamines having 4 to 12 carbon atoms and terephthalic acid and / or isophthalic acid. Furthermore, a modified product of the above polycondensate may be used. Of these, polyamide 6T / 6I, modified polyamide 6T, polyamide 6T / 66, polyamide 6T / 6, and polyamide 9T are preferably used from the viewpoint of a balance between heat resistance and handleability. These aromatic polyamide resins may be used alone or in combination of two or more.

  From the viewpoint of heat resistance, the melting point of the aromatic polyamide resin is preferably 280 ° C. or higher, and more preferably 300 ° C. or higher.

  In the present invention, the content of the aromatic polyamide resin in the aromatic polyamide resin composition is preferably 90 to 99.9% by mass, more preferably 92 to 99.9% by mass, More preferably, it is -99 mass%. When the content is less than 90% by mass, the homogeneity of the aromatic polyamide resin composition may be lost and foaming may be difficult or heat resistance may be impaired. On the other hand, when the content exceeds 99.9% by mass. In some cases, the blending amount of the polyfunctional compound is reduced and the blending effect cannot be obtained.

  Aromatic polyamide resins generally have low melt tension and do not have foamability. On the other hand, in the present invention, a resin composition having foamability can be obtained by reacting the aromatic polyamide resin with a polyfunctional compound to increase the melt tension.

  That is, in the present invention, the polyfunctional compound increases the melt tension of the resin composition when used with the aromatic polyamide resin, and is a compound having a large number of functional groups. Of these, compounds having 2 to 100 functional groups per molecular chain are preferred.

  Specifically, the polyfunctional compound used in the present invention is preferably a polyfunctional epoxy compound, a polyfunctional isocyanate compound, a polyfunctional carbodiimide compound, or a polyfunctional carboxylic acid anhydride, and these may be used alone or in combination of two or more. Can be used. Of these, polyfunctional epoxy compounds are preferably used from the viewpoints of reactivity, reaction temperature, versatility, and cost.

  As the polyfunctional epoxy compound, a polyglycidyl ether compound which is a low molecular polyfunctional epoxy compound (for example, “SR-TMP” manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., “Denacol EX-521” manufactured by Nagase ChemteX Corp.), polyethylene, etc. Multifunctional epoxy compound (for example, “Bondfast E” manufactured by Sumitomo Chemical Co., Ltd.), a polyfunctional epoxy compound (for example, “Reseda GP-301” manufactured by Toagosei Co., Ltd., manufactured by Toagosei Co., Ltd.) "ARUFON UG-4000", "Maybrene KP-7653" manufactured by Mitsubishi Rayon Co., Ltd.), polyfunctional epoxy compounds mainly composed of acrylic / styrene copolymer (for example, "Joncryl-ADR-4368" manufactured by BASF, Toago Synthetic "ARUFON UG-4040"), silicone acrylic copolymer And polyfunctional epoxy compounds mainly composed of polyethylene glycol (for example, “Methbrene S-2200”), polyfunctional epoxy compounds mainly composed of polyethylene glycol (for example, Epiol “E-1000” manufactured by NOF Corporation) and the like. It is done.

  Examples of the polyfunctional isocyanate compound include monomeric MDI (MDI: methylenebis (4,1-phenylene) diisocyanate), polymeric MDI (for example, “Millionate MR-200” manufactured by Nippon Polyurethane Industry Co., Ltd., “Lupranate M20S” manufactured by BASF, etc.) And aromatic polyisocyanate (for example, “Millionate MT” manufactured by Nippon Polyurethane Industry Co., Ltd.).

  Examples of the polyfunctional carbodiimide compound include aromatic polycarbodiimides (for example, “STABAKZOL P” and “STABAKZOL P-400” manufactured by Rhein Chemie), aliphatic (alicyclic) polycarbodiimides (for example, Nisshinbo Industries, Ltd.) “Carbodilite LA-1”, etc.).

  Examples of the polyfunctional oxazoline compound include aromatic polyoxazolines such as 1,3-phenylene-bisoxazoline, oxazoline-containing polymers (for example, “Epocross” manufactured by Nippon Shokubai Co., Ltd.), and the like.

  Examples of the polyfunctional carboxylic acid anhydride include pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, diphenylsulfonetetracarboxylic dianhydride, and the like.

  The molecular weight of the polyfunctional compound as described above is preferably 2000 to 200000, more preferably 2000 to 100000, and further preferably 5000 to 50000. When the molecular weight is less than 2,000, problems such as decomposition, volatilization, and non-uniform dispersion may occur when reacting with an aromatic polyamide by melt kneading, and operability and manufacturability may be reduced. On the other hand, if the molecular weight exceeds 200,000, the effect of increasing the melt tension may be small or may not be uniformly dispersed.

  In addition, the said molecular weight can use the weight average molecular weight measured using gel permeation chromatography (GPC). The eluent used in the measurement is selected in consideration of the solubility of the sample in the eluent, and examples thereof include chloroform, hexafluoroisopropanol, and tetrahydrofuran.

  The content of the polyfunctional compound in the resin composition of the present invention is preferably 0.1 to 10% by mass, more preferably 0.2 to 7% by mass, and 0.3 to 5% by mass. More preferably. If the content of the polyfunctional compound is less than 0.1% by mass, the effect of blending cannot be obtained. On the other hand, if the content exceeds 10% by mass, the fluidity at the time of melting becomes poor and the handling becomes difficult. There is.

  In the aromatic polyamide resin composition of the present invention, the melt tension measured at a temperature of (the melting point of the aromatic polyamide resin composition + 20 ° C.) is required to be 60 to 500 mN, preferably 100 to 400 mN. 100 to 300 mN is more preferable. In a resin composition having a melt tension of less than 60 mN, foam breakage increases in the foaming step, making it difficult to obtain a foam. On the other hand, if the resin composition exceeds 500 mN, the viscosity becomes too high to be melt extruded.

  The melt tension is measured by the following method. That is, the pellet-shaped resin composition dried in advance is placed in a cylinder of a capillometer (trade name “Capillograph 1C” manufactured by Toyo Seiki Seisakusho Co., Ltd.) set at a temperature of (melting point of aromatic polyamide resin composition + 20 ° C.). Fill and place the piston on the cylinder and preheat for 5 minutes. Thereafter, the strand extruded at a piston speed of 10 mm / min is drawn from the die (diameter 1 mm × length 10 mm) at the bottom of the cylinder at an initial speed of 1 mm / min, and the tension is detected with a tensiometer. The take-up speed is gradually increased and the tension when the strand breaks is defined as the value of melt tension (mN).

  Further, in the aromatic polyamide resin composition of the present invention, when this resin composition is made into a foam, a bubble regulator may be added in advance for the purpose of obtaining finer bubbles. Or you may add a bubble regulator at the time of foaming. Examples of the air conditioner include titanium oxide, talc, kaolin, clay, calcium silicate, silica, sodium citrate, calcium carbonate, diatomaceous earth, calcined perlite, zeolite, bentonite, glass, limestone, calcium sulfate, aluminum oxide, titanium oxide. , Magnesium carbonate, sodium carbonate, ferric carbonate, polytetrafluoroethylene powder and the like. Such a bubble regulator preferably has an average particle diameter of 100 μm or less from the viewpoint of reducing the generated bubbles.

  The addition amount (content) of the bubble regulator is preferably 0.01 to 5% by mass and more preferably 0.1 to 3% by mass with respect to the resin composition. If it is less than 0.01% by mass, the foam bubbles may be coarse and the appearance may be impaired. On the other hand, if it exceeds 5% by mass, foam breakage frequently occurs during extrusion foaming, and the closed cell ratio may be lowered or the appearance may be impaired.

  In addition, the aromatic polyamide resin composition of the present invention may contain other resin components in addition to the aromatic polyamide resin and the polyfunctional compound which are the main components, as long as the effects of the present invention are not impaired.

  Other resin components include aliphatic polyamide resin, polyester resin, polyolefin resin, polystyrene resin, polyacrylic acid, polycarbonate resin, polyarylate resin, fluororesin, polyacetal resin, polyvinylidene fluoride, polysulfone, PPS, polyethersulfone, Examples thereof include elastomers such as phenoxy resin, PPO, polyether ketone, and polybutadiene. These resins may be used alone or in combination of two or more.

  From the viewpoint of maintaining the uniformity and heat resistance of the resin composition, the blending amount of other resin components other than the aromatic polyamide resin is preferably 10% by mass or less with respect to the entire resin composition. More preferably, it is 5 mass% or less.

  Further, in the aromatic polyamide resin composition of the present invention, a heat stabilizer, an antioxidant, a pigment, a weathering agent, a flame retardant, a plasticizer, a dispersant, a lubricant, in a range not impairing the effects of the present invention, It is also possible to add a release agent, an antistatic agent, a crosslinking agent, a chain extender, a terminal blocker, a filler, a reinforcing material, and the like. These additives are generally added during polymerization, melt kneading, or extrusion foaming.

  Examples of heat stabilizers and antioxidants include phosphite organic compounds, hindered phenol compounds, benzotriazole compounds, triazine compounds, hindered amine compounds, sulfur compounds, copper compounds, alkali metal halides, and phosphorus compounds. Alternatively, a mixture of these can be used.

  Examples of the terminal blocking agent include carbodiimide compounds, oxazoline compounds, and epoxy compounds other than the polyfunctional compounds used in the present invention. Dispersants include industrial oils such as liquid paraffin, mineral oil, creosote oil, lubricating oil, silicone oil, or vegetable oils such as corn oil, soybean oil, rapeseed oil, palm oil, linseed oil, jojoba oil, or ionic And nonionic surfactants.

  Examples of the filler include inorganic fillers and organic fillers. Inorganic fillers include talc, layered silicate, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon , Carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, glass fiber, carbon fiber and the like. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran and kenaf, and modified products thereof. These additives may be used alone or in combination of two or more.

  The method for producing the resin composition of the present invention is not particularly limited as long as the aromatic polyamide resin and the polyfunctional compound are uniformly kneaded. For example, a melt kneading method using a normal extruder is used. Can do.

  Next, the foam of the present invention will be described. The foam of the present invention is obtained by foaming the aromatic polyamide resin composition of the present invention with a foaming agent. As the foaming agent, a pyrolytic foaming agent, a physical foaming agent, or the like can be used.

  The pyrolytic foaming agent is a foaming agent that generates a gas when heated to a temperature equal to or higher than the decomposition temperature and foams the resin. Specific examples thereof include azo compounds represented by azodicarbonamide and barium azodicarboxylate, nitroso compounds represented by N, N′-dinitrosopentamethylenetetramine, and 4,4′-oxybis (benzenesulfonylhydrazide). And hydrazine compounds represented by hydradicarbonamide, tetrazole compounds, and inorganic foaming agents such as sodium hydrogen carbonate. These may be used alone or in combination of two or more. Of these, a tetrazole compound having a high decomposition temperature is preferable.

Although the method of mix | blending a thermally decomposable foaming agent with a resin composition is not specifically limited, For example, the method etc. which supply a thermally decomposable foaming agent to an extruder with a resin composition are mentioned.
A physical foaming agent is a foaming agent that foams a resin with a gas expanded by a temperature change or a pressure change without a chemical reaction. Physical foaming agents include inorganic compounds such as nitrogen, carbon dioxide and water, various hydrocarbons such as methane, ethane, propane, butane and pentane, chlorofluorocarbon compounds, ethers such as dimethyl ether and methyl ethyl ether, ethanol and methanol, etc. And organic solvents represented by various alcohols.

  Although the method of mix | blending a physical foaming agent with a resin composition is not specifically limited, For example, the method of supplying a resin composition to an extruder and inject | pouring a physical foaming agent from the middle of an extruder is mentioned.

  0.05-10 mass% is preferable with respect to the resin composition, and, as for the compounding quantity of the above-mentioned foaming agent, 0.1-6 mass% is more preferable. When the blending amount of the foaming agent is less than 0.05% by mass, a foam that is sufficiently foamed (the foaming ratio is high) may not be obtained. On the other hand, if the blending amount of the foaming agent exceeds 10% by mass, foam breakage may occur or bubbles may be coalesced inside the foam and the appearance of the foam may be impaired.

  A publicly known and commonly used method can be applied to the foaming method for producing the foam. For example, by using an extruder, the resin composition is extruded and foamed from a slit nozzle into a sheet (foamed sheet), or extruded and foamed from a round nozzle to form a strand (foamed strand). Obtainable. Furthermore, the foam can be formed into particles by cutting the foamed sheet or the foamed strand. The obtained extruded foam can be thermoformed as it is, or cut into foamed particles and then molded in a mold.

  In addition, as a method of obtaining the foam of the present invention, particles of a resin composition are prepared in advance, impregnated with the above-described foaming agent such as hydrocarbon, organic solvent, water and the like, and then subjected to temperature and pressure. It is also possible to apply a method in which foamed particles are produced by foaming in accordance with the above change, and then the foamed particles are molded in a mold.

  As the extruder used for producing the foam of the present invention, a known and commonly used foaming extruder can be suitably used. Examples thereof include a single-screw extruder, a twin-screw extruder, and a tandem type extruder in which a plurality of extruders are connected.

  The foam of the present invention is used for packaging materials, packaging materials, cushioning materials, heat insulating materials, heat insulating materials, cold insulating materials, sound deadening materials, sound absorbing materials, sound insulating materials, vibration damping materials, building materials, cushion materials, materials, containers, etc. be able to. Specific examples include sofas, bed mats, chairs, bedding, mattresses, light covers, plush toys, slippers, cushions, helmets, carpets, pillows, shoes, pouches, mats, crash pads, sponges, stationery, toys, DIY supplies, panels , Tatami core materials, mannequins, automotive interior materials / cushions, car seats, deadning, door trims, sun visors, automotive damping materials / sound absorbing materials, sports mats, fitness equipment, sports protectors, beat boards, ground fences, leisure Sheets, medical mattresses, medical supplies, care supplies, rehabilitation supplies, heat insulating materials for construction, building joint materials, face door materials, building curing materials, reflective materials, industrial trays, tubes, pipe covers, air conditioner heat insulating piping, gasket cores Wood, concrete formwork, civil joints, icicle prevention panels Protective materials, lightweight soil, embankment, artificial soil, packaging materials / packaging materials, packaging materials, wrapping, packaging materials / packaging materials for fresh products / vegetables / fruits, packaging materials / buffer packaging materials for electronic devices, fresh products / Examples include heat and cold boxes for vegetables and fruits, food containers such as cup ramen and lunch boxes, edible trays, beverage containers, agricultural materials, foam models, and diaphragms for speakers.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the measurement and evaluation of the characteristic value in an Example and a comparative example were performed as follows.
(1) Melt tension The melt tension of the obtained aromatic polyamide resin composition was measured by the method described above.
(2) Melting point of aromatic polyamide resin Using a differential scanning calorimeter (trade name “DSC7” manufactured by Perkin Elmer Co., Ltd.), the temperature was raised from 25 ° C. to 400 ° C. at + 10 ° C./min, and held at 40 ° C. for 10 minutes. . Thereafter, the temperature was lowered to 0 ° C. at −10 ° C./min and held for 10 minutes. The temperature was raised again to 400 ° C. at + 10 ° C./min. The peak top was read from the chart during the second temperature increase, and the melting point was determined.

(3) Foaming performance Aromatic polyamide resin composition (before foaming) and the mass of the foamed material are measured, and the apparent volume thereof is determined by a wet electronic hydrometer (trade name “EW-300SG” manufactured by Alpha Mirage). It measured using. For the resin composition and the foam, the apparent density was calculated from the ratio of the apparent volume to the mass. And the foaming ratio was computed from the following formula | equation.
Foaming ratio of foam = (apparent density of resin composition) / (apparent density of foam)
Furthermore, the foaming performance was evaluated according to the following criteria.
○: The expansion ratio is 5 times or more.
X: The expansion ratio is less than 5 times.
(4) Heated dimensional stability (heat resistance)
The obtained foamed sheet was heat-treated at 210 ° C. for 24 hours with a hot air dryer. The length and width of the foamed sheet before and after the heat treatment were measured, and the dimensional change rate in the length and width was calculated from the following formula.
Dimensional change rate (%) = [(Y−X) / X] × 100
X: Length of foamed sheet before heat treatment, or width Y: Length of foamed sheet after heat treatment, or width Evaluation was made according to the following two-stage criteria depending on the value of the dimensional change rate.
○: Both length change rate and width change rate are less than ± 3% ×: at least one of length change rate and width change rate is ± 3% or more

The various raw materials used in the examples and comparative examples are shown below.
(1) Polyamide resin [Aromatic polyamide resin]
A: Polyamide 9T (“Genesta N1000A” manufactured by Kuraray Co., Ltd.) (melting point: 305 ° C., melt tension: 20 mN)
B: Modified polyamide 6T (“Aren E” manufactured by Mitsui Chemicals) (melting point: 320 ° C., melt tension: 15 mN)
[Aliphatic polyamide resin]
C: Polyamide 6 (“A1030BRL” manufactured by Unitika) (melting point: 220 ° C., melt tension: 5 mN)

(2) Polyfunctional compound / Polyfunctional epoxy compound D: Epoxy group-containing acrylic polymer (“Blenmer CP-50M” manufactured by NOF Corporation, weight average molecular weight: 10,000)
E: Epoxy group-containing styrene / acrylic copolymer ("Joncry ADR 4368" manufactured by BASF AG, weight average molecular weight: 6800)
F: Polyethylene glycol diglycidyl ether (“Epiol E-1000” manufactured by NOF Corporation, weight average molecular weight: 1100)
G: Trimethylolpropane polyglycidyl ether ("SR-TMP" manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., weight average molecular weight: 254)
H: Epoxy-modified acrylic (manufactured by Toagosei Co., Ltd., “ARUFON UG-4070”, weight average molecular weight: 9700)
Polyfunctional carbodiimide compound I: carbodiimide (“Carbodilite LA-1” manufactured by Nisshinbo Industries, Ltd., weight average molecular weight: 5000)

(3) Foaming agent K: carbon dioxide (4) Bubble regulator L: fine powder talc (trade name “MW-HST” manufactured by Hayashi Kasei Co., Ltd., average particle size: 2.5 μm)

Example 1
Twin-screw extrusion kneader (Ikegai, “PCM-30”) (screw diameter: 29 mm, L / D: 30, nozzle: 4 mm × 3 holes, upstream temperature: 260 ° C., midstream and downstream temperature: 320 ° C. Then, 99.4 parts by mass of sufficiently dried A and 0.6 part by weight of D were fed and extruded at a discharge rate of 3 kg / h. The strand was cut into pellets, and an aromatic polyamide resin composition M was obtained.

Examples 2-7, Comparative Examples 1-2
Aromatic polyamide resin compositions N to U were obtained in the same manner as in Example 1 except that the type of aromatic polyamide resin, the type of polyfunctional compound, and the blending amounts thereof were changed as shown in Table 1. In Example 2, the temperature of the extruder was changed as follows.
Upstream temperature: 260 ° C., midstream to downstream temperature: 330 ° C., die outlet temperature: 330 ° C.

Comparative Example 3
An aliphatic polyamide resin composition V was obtained in the same manner as in Example 1 except that the aliphatic polyamide resin C was used in place of the aromatic polyamide resin. The temperature of the extruder was changed as follows.
Upstream temperature: 210 ° C, midstream to downstream temperature: 240 ° C, die outlet temperature: 240 ° C

  Table 1 shows the characteristic values of the resin compositions M to V obtained in Examples 1 to 7 and Comparative Examples 1 to 3.

Example 8
Twin screw extrusion foaming machine (Ikegai, “PCM-30”) (screw diameter: 29 mm, L / D: 30, die; 0.8 mmt × 33 mm slit, upstream temperature; 330 ° C., midstream and downstream temperature; 290 ° C., die outlet temperature; 280 ° C.), 99 parts by mass of M and 1 part by mass of fine talc were supplied and extruded at a discharge rate of 5 kg / h. Using a liquefied carbon dioxide injection device (Showa Carbon Dioxide Co., Ltd.), carbon dioxide was injected from the middle of the extruder to cause extrusion foaming to produce a sheet-shaped foam. The foaming ratio of the foamed sheet obtained at this time was 7 times.

Examples 8-14, Comparative Examples 4-8
As shown in Table 2, extrusion foaming was performed in the same manner as in Example 8 except that the resin compositions N to V or the aromatic polyamide resins A to B were used to obtain a foam sheet. The evaluation results of the foamed sheet obtained at this time are shown in Table 2.

  As is clear from Tables 1 and 2, the aromatic polyamide resin compositions of Examples 1 to 7 obtained by reacting the aromatic polyamide resin and the polyfunctional compound all had a melt tension of 60 mN or more. In Examples 8 to 14 where these were subjected to extrusion foaming, good foams with a foaming ratio of 5 times or more were obtained, and the heat dimensional stability was good and the heat resistance was excellent.

  The aromatic polyamide resin compositions of Comparative Examples 1 and 2 obtained by reacting an aromatic polyamide resin with a low molecular weight polyfunctional compound have a slightly higher melt tension than A, but do not thicken well. The melt tension did not rise sufficiently. For this reason, it was inferior to foaming performance, and in Comparative Examples 4-5 which used these for extrusion foaming, only the foam with a low foaming ratio was obtained.

  Instead of the aromatic polyamide resin, the aliphatic polyamide resin composition of Comparative Example 3 obtained by reacting the aliphatic polyamide resin C with the polyfunctional compound has sufficient melt tension, and this was subjected to extrusion foaming. In Example 6, a good foam having a foaming ratio of 7 times was obtained. However, since it is made of an aliphatic polyamide resin, it has poor heat dimensional stability and insufficient heat resistance.

  In Comparative Examples 7 to 8 where the aromatic polyamide resin was directly subjected to extrusion foaming without using a polyfunctional compound, the melt tension of the resin composition was low, so the foaming performance was poor, and the foaming ratio was low. Only a foam was obtained.

Claims (4)

  An aromatic polyamide resin composition comprising an aromatic polyamide resin and a polyfunctional compound, the melt tension when measured at (melting point of the aromatic polyamide resin composition + 20) ° C. is 60 to 500 mN An aromatic polyamide resin composition characterized by that.   The fragrance according to claim 1, wherein the polyfunctional compound is at least one selected from a polyfunctional epoxy compound, a polyfunctional isocyanate compound, a polyfunctional carbodiimide compound, a polyfunctional oxazoline compound, and a polyfunctional carboxylic anhydride. Group polyamide resin composition.   3. The aromatic polyamide resin composition as a whole, comprising 100 parts by mass, comprising 90 to 99.9 parts by mass of an aromatic polyamide resin and 0.1 to 10 parts by mass of a polyfunctional compound. Aromatic polyamide resin composition.   The foam formed by making the aromatic polyamide resin composition in any one of Claims 1-3 foam.