JP6562738B2 - Polyamide resin foam - Google Patents

Description

  The present invention relates to a polyamide resin foam.

  Polyamides represented by polyamide 6 (hereinafter also referred to as “PA6”) and polyamide 66 (hereinafter also referred to as “PA66”) and the like are excellent in molding processability, mechanical properties, and chemical resistance. Widely used as various parts materials for automobiles, electric and electronic, industrial materials, industrial materials, daily necessities and household products.

  Currently, in the automobile industry, weight reduction of vehicle bodies is required to reduce exhaust gas as an environmental effort. In order to meet this demand, polyamides are increasingly used in place of metals as exterior materials and interior materials for automobiles.

  Recently, further weight reduction has been demanded, and expectations for resin foams are increasing. However, general-purpose foams are general-purpose resins such as polyethylene, polystyrene, and polypropylene, and their heat resistance is not sufficient. Therefore, development of a foam having higher heat resistance is required.

  However, although polyamide resin can be expected to have high heat resistance, it is inherently low in melt physical properties such as melt viscosity and melt tension, and it is difficult to foam without modification.

In order to solve the above problems, a method is known in which a modifier, a crosslinking agent, and a foaming agent are added, and the foaming agent is dissolved and the foaming is performed while the polyamide resin is thickened in a single screw extruder. ing.
For example, Patent Document 1 describes a method in which a crosslinking agent is added to polyamide and the resulting mixture is extruded and foamed to obtain a foam.
Patent Document 2 discloses that a polyamide having a compound having three or more carboxylic acid anhydride groups in one molecule, or an α, β-unsaturated carboxylic acid anhydride, and styrene and / or olefin ( A method is described in which a co) polymer is added, extruded and foamed. In this case, the melt viscosity is drastically improved by three-dimensionally bonding the polyamide around the crosslinking agent.

Japanese Examined Patent Publication No. 7-76285 JP 2000-86800 A

The polyamide-based resin foam described in Patent Document 1 can only be obtained as a rod-like foam, and it is difficult to obtain a plate-like or sheet-like foam, and melting for obtaining a sheet-like foam. The physical properties were not sufficient, and the processability was poor. Further, the polyamide-based resin foam described in Patent Document 2 has high reactivity between the polyamide and the functional group of the crosslinking agent, and in order to make the resin temperature uniform at a lower temperature, the residence time in the extruder is increased. , The crosslinking reaction proceeds more than necessary, or the melt viscosity varies due to the difference in the degree of crosslinking, making it easy to tear when taking the foam, and the melt viscosity at a high shear rate becomes high and fluidity , The foamability of extrusion deteriorates.
Then, an object of this invention is to provide the polyamide-type resin foam excellent in heat resistance, extrusion processability, and extrusion foamability.

  As a result of intensive studies to solve the above problems, the present inventor has found that the melt viscosity (A) at a frequency of 0.1 rad / s measured at a melting point + 30 ° C. and the melt viscosity (B) at a frequency of 10 rad / s. ) Ratio (A / B) is a polyamide-based resin composition comprising a polyamide-based resin composition including a polyamide-based resin within a certain range, and found that the above-mentioned problems can be solved, thereby completing the present invention. It came to do.

That is, the present invention is as follows.
[1] The ratio (A / B) of the melt viscosity (A) at a frequency of 0.1 rad / s and the melt viscosity (B) at a frequency of 10 rad / s measured at a temperature of melting point + 30 ° C. is 3 to 7 A polyamide-based resin foam comprising a polyamide-based resin composition comprising a polyamide-based resin and an isocyanurate-based compound .
[2] The polyamide resin foam according to [1], wherein the polyamide resin composition contains 0.05 to 7 parts by mass of an isocyanurate compound with respect to 100 parts by mass of the polyamide resin.

ADVANTAGE OF THE INVENTION According to this invention, the polyamide-type resin foam excellent in heat resistance, extrusion processability, and extrusion foamability can be provided.
Especially the polyamide-type resin foam of this invention can be used suitably for the motor vehicle member used on high temperature conditions.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

  The polyamide-based resin foam of the present embodiment is composed of a polyamide-based resin composition, and the composition preferably includes a polyamide-based resin and, if necessary, other components such as a crosslinking agent and a cell regulator. .

  The polyamide-based resin used in the present embodiment has an amide bond (—NHCO—) obtained by a polymer obtained by self-condensation reaction of aminocarboxylic acid, ring-opening polymerization of lactam, and polycondensation of diamine and dicarboxylic acid. It means a polymer having in the main chain.

  The aminocarboxylic acid is not particularly limited, and examples thereof include ω-aminocarboxylic acid and α, ω-amino acid which are compounds in which the lactam is ring-opened. The aminocarboxylic acid is preferably a linear or branched saturated aliphatic carboxylic acid having 4 to 14 carbon atoms substituted at the ω position with an amino group. Such aminocarboxylic acid is not particularly limited, and examples thereof include 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and paraaminomethylbenzoic acid.

  Although it does not specifically limit as lactam, Butyrolactam, pivalolactam, (epsilon) -caprolactam, caprilactam, enantolactam, undecanolactam, laurolactam (dodecanolactam), etc. are mentioned. Among these, as the lactam, ε-caprolactam, laurolactam and the like are preferable, and ε-caprolactam is more preferable.

  Examples of the diamine include ethylene diamine, propylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2-methylpenta. Methylenediamine (also referred to as 2-methyl-1,5-diaminopentane), 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, 2,4-dimethyl Octamethylenediamine, metaxylylenediamine, paraxylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 3,8-bis (a) Nomethyl) tricyclodecane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethyl There are piperazine.

  Examples of dicarboxylic acids include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5 -Sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, diglycolic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid and the like.

Polyamide resins used in this embodiment include polycaproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide). 610), polyhexamethylene dodecamide (polyamide 612), polyundecamethylene adipamide (polyamide 116), polyundecanamide (polyamide 11), polydodecanamide (polyamide 12), polytrimethylhexamethylene terephthalamide (polyamide TMHT) ), Polyhexamethylene isophthalamide (polyamide 6I), polyhexamethylene terephthalate / isophthalamide (polyamide 6T / 6I), polybis (1-aminocyclohexyl) methane dodecamide (polyamide) ACM12), polybis (3-methyl-4-aminocyclohexyl) methane dodecamide (polyamide dimethyl PACM12), polymetaxylylene adipamide (polyamide MXD6), polydecamethylene terephthalamide (polyamide 10T), polypolydedecane terephthalamide (Polyamide 11T), polyundecamethylene hexahydroterephthalamide (polyamide 11T (H)), isophthalic acid / terephthalic acid / 1,6-hexanediamine polycondensate (amorphous polyamide), isophthalic acid / terephthalic acid / Examples include 1,6-hexanediamine / bis (3-methyl-4-aminocyclohexyl) methane polycondensates (amorphous polyamide), copolymerized polyamides thereof, and mixed polyamides. Among these, polyamide 6, polyamide 66, and amorphous polyamide are particularly preferable from the viewpoint of excellent heat resistance and easy extrusion. More preferably, polyamide 6 and polyamide 66 are particularly preferable.
The said polyamide-type resin may be used individually by 1 type, and may be used in combination of 2 or more type.

The production method of the polyamide-based resin is not particularly limited, and examples thereof include a method of producing by a generally known melt polymerization method or further using a solid phase polymerization method in combination.
The method for producing the polyamide-based resin is not particularly limited, and may be a batch type or a continuous type. The polymerization apparatus is not particularly limited, and examples thereof include known apparatuses such as an autoclave type reactor, a tumbler type reactor, and an extruder type reactor such as a kneader.

  Although it does not specifically limit as a crosslinking agent used for this embodiment, The polyfunctional monomer which has at least 2 or more carbon-carbon double bond in a molecule | numerator is mentioned. Isocyanurate compounds such as triallyl isocyanurate, trimethallyl isocyanurate, and triglycidyl isocyanurate are preferred from the viewpoint of improving melt viscosity in the low angular velocity region, stability during extrusion, sheet take-up property, and corrugation suppression. More preferred are triallyl isocyanurate and trimethallyl isocyanurate, and further preferred is trimethallyl isocyanurate.

It is preferable that content of the crosslinking agent in the polyamide-type resin composition of this embodiment is 0.05-7 mass parts with respect to 100 mass parts of polyamide-type resins, More preferably, it is 0.05-5 mass parts. It is. When the content of the crosslinking agent is 0.05 parts by mass or more, the melt viscosity is appropriately improved, foam breakage hardly occurs during extrusion foaming, and it becomes difficult to tear when taking the foamed sheet. On the other hand, when it is 7 parts by mass or less, the generation of gel and decomposition gas can be suppressed, the effect of preventing sheet tearing can be easily obtained, and the surface appearance is improved.
The crosslinking agent of this embodiment may be used individually by 1 type, and may be used in combination of 2 or more type.

  The polyamide resin composition of the present embodiment has a melt viscosity (A) at a frequency of 0.1 rad / s and a frequency of 10 rad / s measured at a melting point of the polyamide resin contained in the polyamide resin composition + 30 ° C. The melt physical properties are within a certain range (A / B) with the melt viscosity (B).

When the melt viscosity at a frequency of 0.1 rad / s is low as in a normal polyamide-based resin, bubbles tend to break during extrusion foaming. On the other hand, when the melt viscosity at a frequency of 10 rad / s is too low, it is difficult to maintain the shape of the sheet. On the other hand, when the melt viscosity is too high, the load on the extruder increases, leading to strand breakage and torque over.
In order to achieve both extrudability and foamability, the balance between the melt viscosity (A) at a frequency of 0.1 rad / s and the melt viscosity (B) at a frequency of 10 rad / s is important, and (A) and (B ) Ratio is preferably within an appropriate range.

The ratio (A / B) of (A) and (B) is 3-7, preferably 3-5.
When the ratio of (A) and (B) is lower than 3, foaming tends to break during extrusion foaming, it is difficult to maintain the sheet shape, and it is difficult to obtain a desired foam, and extrusion is difficult due to torque over. There is a case. Moreover, it becomes easy to tear when the take-up speed of a foam sheet becomes high.
On the other hand, if the ratio of (A) to (B) is higher than 7, the growth of bubbles is inhibited at the time of extrusion foaming, it is difficult to obtain a foam having a high foaming ratio, and the foamed sheet is torn at the time of take-up.

  In addition to the polyamide-based resin and the crosslinking agent, the polyamide-based resin composition of the present embodiment includes, as other components, a bubble regulator, a stabilizer, an impact modifier, a flame retardant, a lubricant, a pigment, a dye, and a weather resistance improver. In addition, an antistatic agent, an impact modifier, a crystal nucleating agent, glass beads, an inorganic filler, and other thermoplastic resins may be added as long as the object of the present invention is not impaired.

  Moreover, when this resin composition is made into a foam, a foam regulator may be added to the polyamide resin composition of this embodiment 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 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.

  As addition amount (content) of a bubble regulator, 0.01-5 mass parts is preferable with respect to 100 mass parts of polyamide-type resin, and 0.1-3 mass parts is more preferable. When the amount is 0.01 parts by mass or more, the foam bubbles are moderate and the appearance is good. Moreover, when it is 5 parts by mass or less, bubble breakage hardly occurs at the time of extrusion foaming, the closed cell ratio is hardly lowered, and the appearance is improved.

  Examples of the stabilizer include, but are not limited to, organic antioxidants such as hindered phenol antioxidants, sulfur antioxidants, phosphorus antioxidants, phosphite compounds, thioether compounds, and the like. Examples include heat stabilizers; hindered amine-based, benzophenone-based, imidazole-based light stabilizers and ultraviolet absorbers; metal deactivators, and the like. These may be used alone or in combination of two or more.

  As a heat stabilizer, a copper compound is preferable from the viewpoint of effectively preventing long-term heat aging in a high temperature environment of 120 ° C. or higher, and a combination of this copper compound and an alkali metal halide compound is also preferable. Here, alkali metal halide compounds include lithium chloride, lithium bromide, lithium iodide, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, potassium fluoride, potassium chloride, potassium bromide, and iodide. Potassium etc. are mentioned. These may be used alone or in combination of two or more.

  The method for producing the polyamide resin foam of the present embodiment is not particularly limited, but a known foaming method can be used. For example, using an extruder, a foaming agent is injected into the melted polyamide-based resin composition of the present embodiment and extruded and foamed from a slit die to form a foamed sheet, or extruded and foamed from a round die to form a strand. (Polymerized strand) or a polyamide-based resin foam can be obtained.

  Although it does not specifically limit as a foaming agent, A thermal decomposition type foaming agent, a physical foaming agent, etc. are mentioned.

  Preferable examples of the pyrolytic foaming agent include azo compounds represented by azodicarbonamide and barium azodicarboxylate, nitroso compounds represented by N, N′-dinitrosopentamethylenetetramine, 4,4′-oxybis ( Examples thereof include hydrazine compounds typified by benzenesulfonyl hydrazide) and hydradicarbonamide, tetrazole compounds, and inorganic foaming agents such as sodium hydrogen carbonate. These may be used alone or in combination of two or more.

  Preferred as the physical foaming agent are inorganic compounds such as carbon dioxide, nitrogen, oxygen, hydrogen, argon, helium, neon, water, trichlorofluoromethane (R11), dichlorodifluoromethane (R12), and chlorodifluoromethane (R22). , Tetrachlorodifluoroethane (R112) dichlorofluoroethane (R141b) chlorodifluoroethane (R142b), difluoroethane (R152a), fluorocarbons such as HFC-245fa, HFC-236ea, HFC-245ca, HFC-225ca, HFO-1234y, HFO-1234ze Hydrofluoroolefins such as (E), saturated hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, dimethyl ether, diethyl ether , Ethers such as methyl ethyl ether, isopropyl ether, n-butyl ether, diisopropyl ether, furan, furfural, 2-methyl furan, tetrahydrofuran, tetrahydropyran, and chlorinated hydrocarbons such as methyl chloride and ethyl chloride. It is done. These may be used alone or in combination of two or more.

  0.05-10 mass% is preferable with respect to the polyamide-type resin composition whole quantity, and, as for the addition amount of the above-mentioned foaming agent, 0.1-6 mass% is further more preferable. When the blending amount of the foaming agent is 0.05% by mass or more, it is easy to obtain a foam that is appropriately foamed (high expansion ratio), and when the blending amount of the foaming agent is 10% by mass or less, foam breakage occurs. Since it is difficult to occur and it is difficult for bubbles to coalesce inside the foam, the appearance of the foam is improved.

  Further, as a method for obtaining the polyamide resin foam of the present embodiment, the polyamide resin composition particles are prepared in advance, and the above-mentioned foaming agent such as inorganic compounds, hydrocarbons, ethers, chlorinated hydrocarbons, etc. There is also a method in which pre-expanded particles are prepared by impregnating the particles under pressure and then foaming by changing the temperature or pressure.

  The method for incorporating (impregnating) the foaming agent into the polyamide-based resin composition is not particularly limited. For example, a method in which an aqueous medium is used in a suspension system such as water (suspension impregnation), sodium bicarbonate, or the like. Using a pyrolytic foaming agent (decomposing foaming agent), bringing the gas into an atmosphere above the critical pressure and bringing it into a liquid phase and contacting it with the base resin (liquid phase impregnation), and making the gas an atmosphere below the critical pressure Examples of the method include a method in which a gas phase is brought into contact with the base resin (gas phase impregnation).

A method for causing foaming in a polyamide resin composition containing (impregnated) a foaming agent is not particularly limited. For example, by preliminarily foaming particles by bringing them from a high pressure atmosphere to a low pressure atmosphere, A method of expanding a gas as a foaming agent dissolved therein to generate foam, or a method of expanding a gas in pre-expanded particles by heating using pressure steam or the like to generate foam Etc. can be used.
The pre-expanded particles refer to particles having expandability that are not subjected to final stage expansion.

  The method of molding the polyamide resin pre-expanded particles is not particularly limited. For example, the pre-expanded particles are filled in the cavities of the molding die and heated to cause foaming and at the same time between the pre-expanded particles. After heat sealing, the product can be solidified by cooling and molded. Here, the filling method of the pre-expanded particles is not particularly limited. For example, a cracking method in which the pre-expanded particles are filled with the mold slightly opened, or a pre-compressed pre-pressed particle with the mold closed. Examples thereof include a compression method in which expanded particles are filled, and a compression cracking method in which the above-described cracking method is performed after filling pre-expanded particles that have been compressed into a mold.

The density of the polyamide resin foam of the present embodiment is preferably 0.02 to 0.8 g / cm ³ . When the density is 0.02 g / cm ³ or more, the bubble diameter can be kept uniform, and the thickness of the bubble film can be kept high without being too thin. Moreover, the lightweight property of a foam can be improved by being 0.8 g / cm < ³ > or less.
Further, the closed cell ratio of the polyamide resin foam of the present embodiment is preferably 75% or more. When the closed cell ratio is 75% or more, the strength of the foam can be maintained high and high heat insulation performance can be exhibited.

  Hereinafter, the present invention will be described with reference to specific examples and comparative examples, but the present invention is not limited thereto.

The polyamide resin of Examples and Comparative Examples described later, raw materials of polyamide resin foam, and methods for measuring physical properties are shown below.
[raw materials]
<< (a) Polyamide-based resin >>
(A-1) PA6 (Tm2: 220 ° C., ΔH: 59 J / g, 96% sulfuric acid viscosity ηr: 3.9)
(A-2) PA66 (Tm2: 260 ° C., ΔH: 56 J / g, 96% sulfuric acid viscosity ηr: 2.5)
<< (b) Crosslinking agent >>
(B-1) Trimethallyl isocyanurate (b-2) Triallyl isocyanurate << other components >>
Bubble regulator: Talc (average particle size 6μm)
Organic peroxide: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane

[Measurement method of physical properties]
(1) Melting point Tm2 (° C.), heat of fusion ΔH (J / g)
According to JIS-K7121, DSC7 manufactured by PERKIN-ELMER was used to measure the melting point Tm2 (° C.) and the heat of fusion ΔH (J / g) of the polyamide resins used in Examples and Comparative Examples described later. Specifically, the measurement was performed as follows. First, in a nitrogen atmosphere, about 10 mg of a sample was heated from room temperature to 300 to 350 ° C. according to the melting point of the sample at a temperature rising rate of 20 ° C./min. The temperature of the endothermic peak (melting peak) appearing at this time was defined as Tm1 (° C.). Next, the temperature was maintained for 2 minutes at the highest temperature rise. At this maximum temperature, the polyamide-based resin was in a molten state. Thereafter, the temperature was decreased to 30 ° C. at a temperature decrease rate of 20 ° C./min, and held at 30 ° C. for 2 minutes. Thereafter, the temperature was raised from 30 ° C. to 300 to 350 ° C. according to the melting point of the sample at a heating rate of 20 ° C./min. The maximum peak temperature of the endothermic peak (melting peak) appearing at this time was the melting point Tm2 (° C.), and the total peak area was the heat of fusion ΔH (J / g).
The melting point Tm2 was taken as the melting point (° C.) of the polyamide resin.

(2) Sulfuric acid relative viscosity ηr at 25 ° C
According to JIS-K6810, the sulfuric acid relative viscosity (eta) r of 25 degreeC of the polyamide-type resin used by the below-mentioned Example and comparative example was implemented. Specifically, a 1% concentration solution ((polyamide 1 g) / (96% sulfuric acid 100 mL)) was prepared using 96% sulfuric acid, and a temperature of 25 ° C. was obtained using the obtained solution. The sulfuric acid relative viscosity ηr was measured under the conditions.

(3) Melt Viscosity The polyamide resin compositions obtained in Examples and Comparative Examples are molded using an injection molding machine [PS-40E: manufactured by Nissei Resin Co., Ltd.], so that the length is 60 mm × the width is 60 mm ×. A molded piece having a thickness of 1.0 mm was produced. From there, a cylindrical sample of 1 mmφ was prepared by pressing, and the melt viscosity was measured using a melt viscosity measuring apparatus [ARES-G2: manufactured by TA INSTRUMENTS]. The measurement conditions were a frequency of 100 to 0.01 rad / s, a plate diameter of 25 mm, a gap interval of 0.05 mm, and a measurement temperature of a melting point of polyamide resin (Tm2) + 30 ° C.
Then, “(melt viscosity at a frequency of 0.1 rad / s) / (melt viscosity at a frequency of 10 rad / s)” was calculated.

(4) Density For the polyamide-based resin foams obtained in Examples and Comparative Examples described later, after measuring the mass W (g), the apparent volume Va (cm ³ ) of the foam was measured by a submersion method. . And the value W / Va (g / cm < ³ >) which remove | divided the mass W by the apparent volume Va was made into the density of a foam.

(5) Closed cell ratio About the foam which measured apparent volume Va in above-mentioned (4), the true volume (Vx) was measured using the air comparison type hydrometer (made by Beckman Co., Ltd.). And according to the following formula 1, the closed cell ratio S (%) was calculated.
S (%) = {(Vx−W / ρ) / (Va−W / ρ)} × 100 Equation 1
(Where Vx is the true volume (cm ³ ) of the foam, Va is the apparent volume (cm ³ ) of the foam, W is the mass (g) of the foam, ρ Is the density (g / cm ³ ) of the base resin of the foam.

(6) Average cell diameter of foam The surface orthogonal to the extrusion direction (MD direction) of the polyamide-based resin foam obtained in Examples and Comparative Examples described below was photographed using a scanning electron microscope. The circle equivalent diameter of at least 100 adjacent cells is taken as the cell diameter, and the average value of those 100 cells is obtained, this is performed at any three locations, and the average value of the three average values obtained at the three locations is obtained. The average cell diameter was used.

(7) Biaxial extrudability The polyamide resin composition pellets described in Examples and Comparative Examples were extruded using a twin screw extruder (trade name “TEX30α”, manufactured by Nippon Steel Works) with a screw diameter of 30 mm. During the extrusion process, the temperature of the cylinder was set to the melting point of polyamide resin (Tm2) + 30 ° C., the screw rotation speed was set to 200 rpm, and the discharge rate was set to 15 kg / h. When 5 strands were drawn in the time zone from 30 minutes to 3 hours after the start of extrusion, the number of strands that could be stably pulled was visually evaluated according to the following criteria. It was judged that the greater the number of strands that could be stably pulled, the better the extrudability.
○: 5 of the 5 strands can be picked up. Δ: 3 to 4 of the 5 strands can be picked up. X: 0 to 2 of the 5 strands can be picked up.

(8) Extrusion foamability Extrusion foam sheets obtained in Examples and Comparative Examples were observed, and extrusion foamability was evaluated according to the following criteria.
◯: No sheet sagging or die clogging due to its own weight, and the sheet was obtained stably for 2 hours from the start of production of the extruded foam sheet.
Δ: Within 2 hours from the start of production of the extruded foam sheet, the sheet formation was unstable, such as sheet dropping due to its own weight, intermittent die clogging, and the like. The generated die clogging was eliminated by the pressure for extruding the resin, and the sheet could be formed again, and the sheet was obtained continuously for 2 hours.
X: Within 2 hours from the start of production of the extruded foam sheet, the sheet hangs down due to its own weight, continuous die clogging, and the like occurred, and it was difficult to form the sheet.

(9) Stretchability of Extruded Sheet When the extruded foamed sheet that came out from the fishtail die was taken up by a take-up device, the take-up speed at which the take-up becomes impossible due to tearing of the sheet was measured to evaluate stretchability.
It was judged that the higher the take-up speed, the better the extrudability, such as easier corrugation suppression.

(10) Presence / absence of corrugation The presence / absence of corrugation on the sheet surface of the polyamide resin foam obtained in Examples and Comparative Examples was visually confirmed. The case where a corrugate was seen was "Yes", and the case where it was not seen was "No".

Example 1
100 parts by mass of polyamide resin (a-1), 0.2 parts by mass of cross-linking agent (b-1) and 0.1 part by mass of cell regulator are melt-kneaded by a 30 mmφ twin screw extruder to form a pellet-like polyamide resin A composition was prepared. During the extrusion process, the temperature of the cylinder was set to the melting point (Tm2) of the polyamide-based resin (a-1) + 30 ° C., the screw rotation speed was set to 200 rpm, and the discharge rate was set to 15 kg / h.
The obtained polyamide-based resin composition was supplied to a hopper of a 40 mmφ single-screw extruder and melted, and then normal butane was injected as a foaming agent from the middle of the extruder barrel. After butane press-fitting, a screw cooler for making the resin temperature uniform was passed, and an extruded foam sheet of a polyamide-based resin foam was obtained from a fishtail die (slit shape: width 300 mm × thickness 1 mm). The set temperature of each equipment was set to Tm2 + 30 ° C. for the single screw extruder, Tm 2 for the screw cooler, and Tm2 + 5 ° C. for the fishtail die.

(Examples 2-7, Comparative Examples 1-3)
Manufacture was performed in the same manner as in Example 1 except that the polyamide-based resin, the cross-linking agent, and the organic peroxide were the types and addition amounts shown in Table 1.
The evaluation results are shown in Table 1.

  From the results in Table 1, it was confirmed that the polyamide resin foam of the present invention was excellent in extrusion processability and extrusion foamability. Moreover, since the polyamide-type resin foam of this invention uses the amide-type resin, it was excellent also in heat resistance.

Claims (2)

Polyamide having a ratio (A / B) of 3 to 7 of a melt viscosity (A) at a frequency of 0.1 rad / s and a melt viscosity (B) at a frequency of 10 rad / s, measured at a temperature of melting point + 30 ° C. A polyamide-based resin foam comprising a polyamide-based resin composition containing an epoxy resin and an isocyanurate-based compound . The polyamide resin foam according to claim 1, wherein the polyamide resin composition contains 0.05 to 7 parts by mass of an isocyanurate compound with respect to 100 parts by mass of the polyamide resin.