JP2018053184A - Rubber-based foamable resin composition, rubber-based resin closed-cell foam, water-stop sealing material, and method for producing rubber-based resin closed-cell foam - Google Patents

Abstract

A rubber-based foamable resin composition in which a rubber-based resin containing an acrylonitrile component and azodicarbonamide coexist, a rubber-based resin closed cell foam obtained by foaming the rubber-based foamable resin composition, and An object of the present invention is to prevent contamination of a heating furnace peculiar to a method for producing a rubber resin closed cell foam. SOLUTION: A rubber resin (A) containing at least 35% by mass of an acrylonitrile component, azodicarbonamide (B ) And at least one basic magnesium (C) selected from 0.05 to 5 parts by mass of magnesium oxide and magnesium hydroxide with respect to 100 parts by mass of the rubber-based resin (A). Resin composition. [Selection figure] None

Description

  The present invention relates to a rubber-based foamable resin composition, a rubber-based resin closed cell foam, a water sealing material, and a method for producing a rubber-based resin closed cell foam.

Currently, various foams are used in various fields such as architecture, electronics, and vehicles. For example, in order to fill a gap between various structures and prevent water from entering, there are known examples in which a foam is used as a water-stop sealing material and an example in which it is used as a vehicle interior material.
As a foam material, there is a rubber-based resin closed-cell foam formed by foaming a foam resin containing a rubber resin containing acrylonitrile components such as acrylonitrile-butadiene rubber and a certain amount or more and azodicarbonamide. 1 and 2. It is described that the foam is useful as a water-stopping material due to its excellent physical properties.
On the other hand, azodicarbonamide may cause a trace amount of residue to remain in the resin after foaming and cause problems due to the residue. Some of the degradation products of azodicarbonamide are sublimable and may cause fogging. Fogging is a phenomenon in which a minute amount of sublimate generated from a resin material or resin foam used as an interior material adheres to the inner surface of a windshield or the like to cause fogging. Patent Document 3 shows that in an example, a foam obtained by foaming a composition containing a predetermined amount of low density polyethylene, azodicarbonamide, magnesium hydroxide, magnesium oxide, and calcium hydroxide can reduce fogging. Has been.

JP 2014-208771 A International Publication No. 2014/156902 JP 2000-313763 A

By the way, according to the study by the present inventors, the rubber-based resin closed cell foam described in Patent Documents 1 and 2 is excellent in specific physical properties, but is a foamable resin composition that is a raw material for forming a foam. It turned out that contamination of the heating furnace which heats things tends to occur. As a result of further investigation, in consideration of the experimental result that the contamination of the heating furnace does not occur when the polyolefin resin is used as the rubber resin, the contamination of the heating furnace is caused by the rubber resin containing the acrylonitrile component. I guessed it. More specifically, it has been inferred that this is due to a reaction product of sulfur contained as an impurity in the rubber-based resin containing an acrylonitrile component and ammonia generated during thermal decomposition of azodicarbonamide.
That is, the present invention relates to a rubber-based foamable resin composition in which a rubber-based resin containing an acrylonitrile component and azodicarbonamide coexist, and a rubber-based resin closed cell foam formed by foaming the rubber-based foamable resin composition And it aims at solving the above-mentioned subject peculiar to the manufacturing method of this rubber system resin closed cell foam.

As a result of intensive studies to achieve the above object, the present inventors have obtained a rubber-based foamable resin composition further containing basic magnesium in addition to a rubber-based resin containing an acrylonitrile component and azodicarbonamide. When used, it was found that the contamination of the heating furnace can be reduced, and the present invention has been completed.
That is, the present invention relates to the following [1] to [8].
[1] 0.05 to 5 parts by mass of magnesium oxide with respect to 100 parts by mass of the rubber resin (A), azodicarbonamide (B), and the rubber resin (A) containing 35% by mass or more of an acrylonitrile component And a rubber-based foamable resin composition containing at least one basic magnesium (C) selected from magnesium hydroxide.
[2] The rubber system according to [1], wherein in the foamable resin composition, azodicarbonamide (B) is blended in an amount of 5 to 25 parts by mass with respect to 100 parts by mass of the rubber resin (A). Foamable resin composition.
[3] The rubber-based foamable resin composition according to the above [1] or [2], wherein the basic magnesium (C) has an average particle size of 0.1 to 15 μm.
[4] A rubber-based resin closed cell foam having a closed cell ratio of 70% or more obtained by foaming the rubber-based foamable resin composition according to any one of [1] to [3].
[5] The rubber-based resin closed-cell foam according to [4] above, having an apparent density of 20 to 100 kg / m ³ .
[6] The rubber-based resin closed-cell foam according to [4] or [5] above, wherein the closed-cell ratio is 80 to 100%.
[7] A water-stop sealing material comprising the rubber-based resin closed-cell foam according to any one of [4] to [6].
[8] The method for producing a rubber-based resin closed-cell foam according to any one of [4] to [6] above, wherein the rubber-based foamable resin composition is heated inside a heating device. A method for producing a foamed rubber-based resin closed cell foam.

  According to the present invention, the rubber-based foamable resin composition capable of reducing the contamination of the heating furnace and maintaining the desired physical properties when formed into a foam, and foaming the rubber-based foamable resin composition It is possible to provide a rubber-based resin closed cell foam and a method for producing the rubber-based resin closed cell foam.

  The rubber-based foamable resin composition of the present invention is 0 with respect to 100 parts by mass of the rubber-based resin (A), azodicarbonamide (B), and the rubber-based resin (A) containing 35% by mass or more of an acrylonitrile component. 0.05 to 5 parts by mass of at least one basic magnesium (C) selected from magnesium oxide and magnesium hydroxide.

<Rubber resin (A)>
The rubber-based foamable resin composition of the present invention contains a rubber-based resin (A).
The rubber-based resin (A) of the present invention is not particularly limited as long as it contains 35% by mass or more of an acrylonitrile component and has rubber elasticity at room temperature (20 ° C.). When the content of the acrylonitrile component of the rubber-based resin (A) is less than 35% by mass, a dimensional change of the rubber-based resin closed cell foam (hereinafter also simply referred to as a foam) is likely to occur, and the long-term stability is poor. From the viewpoint of improving the long-term stability of the foam, the content of the acrylonitrile component of the rubber-based resin (A) is preferably 35 to 80% by mass, more preferably 35 to 70% by mass, Preferably, it is 40-60 mass%. In addition, when using 2 or more types of rubber-type resin, let the weight average value be content of an acrylonitrile component.

  Examples of the rubber resin (A) include acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (HNBR), carboxylated acrylonitrile-butadiene rubber (XNBR), and acrylonitrile-butadiene-isoprene. Examples thereof include acrylonitrile rubbers such as rubber (NBIR) and acrylonitrile-isoprene rubber (NIR). Among these, acrylonitrile-butadiene rubber is preferable.

The rubber-based resin (A) used in the present invention may be composed of only acrylonitrile-based rubber as long as the amount of the acrylonitrile component is satisfied, and may be composed of acrylonitrile-based rubber and other rubbers. It is preferable to consist only of rubber.
The rubber other than the acrylonitrile rubber constituting the rubber resin (A) is not particularly limited as long as it has rubber elasticity at room temperature (20 ° C.). For example, chloroprene rubber (CR), isoprene Rubber (IR), butyl rubber (IIR), natural rubber (NR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), urethane rubber, fluorine rubber, acrylic rubber, And silicone rubber. These may be used individually by 1 type and may be used in combination of 2 or more type.
When the rubber-based resin (A) is composed of acrylonitrile-based rubber and other rubber, the content of acrylonitrile-based rubber in the rubber-based resin is 80% by mass or more from the viewpoint of improving the water-stopping property of the foam. Preferably, 85 mass% or more is more preferable, and 90 mass% or more is still more preferable.

The rubber-based resin (A) in the present invention may contain a liquid synthetic rubber (hereinafter also referred to as “liquid rubber”) under the conditions of 20 ° C. and 1 atm (1.01 × 10 ⁻¹ MPa). .
When rubber-type resin (A) contains liquid rubber, the kneading | mixing load at the time of manufacture can be reduced.
The liquid rubber means a synthetic rubber having fluidity under the conditions of 20 ° C. and 1 atm (1.01 × 10 ⁻¹ MPa), for example, liquid acrylonitrile-butadiene rubber (liquid NBR), liquid hydrogenation. Acrylonitrile-butadiene rubber (liquid HNBR), liquid carboxylated acrylonitrile-butadiene rubber (liquid XNBR), liquid acrylonitrile-butadiene-isoprene rubber (liquid NBIR), liquid acrylonitrile-isoprene rubber (liquid NIR), and acrylonitrile Acrylonitrile rubbers such as liquid terpolymers of styrene and butadiene and functional monomers having anti-aging functions, etc .; liquid chloroprene rubber (liquid CR), liquid isoprene rubber (liquid IR), liquid butyl rubber (liquid IIR), etc. Is mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.
Among these, from the viewpoint of improving the water-stopping property of the foam, liquid acrylonitrile-based rubber is preferable, and liquid acrylonitrile-butadiene rubber (liquid NBR) is more preferable. In addition, the content of the acrylonitrile component in the liquid acrylonitrile-butadiene rubber (liquid NBR) is preferably 20 to 60% by mass, more preferably 25 to 50% by mass from the viewpoint of improving the long-term stability of the foam. %, And more preferably 30 to 40% by mass.

  The rubber-based resin (A) containing an acrylonitrile component such as acrylonitrile-butadiene rubber generally contains a sulfur content as an impurity. The sulfur content in the rubber-based resin (A) reacts with ammonia generated during the thermal decomposition of azodicarbonamide, and as described above, is estimated to cause contamination of a heating device such as a heating furnace. As will be described later, such contamination can be prevented by using basic magnesium (C) in combination.

<Azodicarbonamide (B)>
The rubber-based foamable resin composition of the present invention contains azodicarbonamide (B). Azodicarbonamide (B) is a thermally decomposable foaming agent that decomposes and foams when heated. For example, the azodicarbonamide (B) is decomposed in a heating furnace to foam a rubber-based foamable resin composition.
In the rubber-based foamable resin composition, the azodicarbonamide (B) is preferably blended in an amount of 5 to 25 parts by mass, and 10 to 20 parts by mass with respect to 100 parts by mass of the rubber-based resin (A). Is more preferable.
(B) By making the compounding quantity of a component into the said range, it becomes easy to foam appropriately without bursting the bubble of a foam. It is also possible to form a foam having a relatively high expansion ratio (that is, a low density).

<Basic magnesium (C)>
The rubber-based foamable resin composition of the present invention contains basic magnesium (C). The basic magnesium (C) is at least one selected from magnesium oxide and magnesium hydroxide. The rubber-based foamable resin composition of the present invention may contain only one or both of magnesium oxide and magnesium hydroxide as the component (C).
By mixing basic magnesium, contamination of the heating furnace can be reduced. This is because the ammonia component generated during the thermal decomposition of azodicarbonamide is absorbed by basic magnesium, and therefore the production of azodicarbonamide reactants (such as ammonium sulfate), which is considered to be a cause of contamination of the heating furnace, is caused. It is presumed to be suppressed.

The basic magnesium (C) in the rubber-based foamable resin composition is blended in an amount of 0.05 to 5 parts by mass with respect to 100 parts by mass of the rubber-based resin (A). If the blending amount of the component (C) is less than 0.05 parts by mass relative to 100 parts by mass of the rubber-based resin (A), contamination of the heating furnace tends to occur, and if it exceeds 5 parts by mass, the thickness of the foam and the appearance It becomes difficult to maintain desired physical properties such as density and adhesion to the adherend.
From the above viewpoint, the basic magnesium (C) is preferably blended in an amount of 0.1 to 5 parts by mass, and preferably 0.2 to 4 parts by mass with respect to 100 parts by mass of the resin (A). More preferred.

The average particle diameter of basic magnesium (C) is preferably 0.1 to 15 μm. By setting the average particle size within the above range, desired physical properties as a foam can be maintained. From these viewpoints, the average particle size of the basic magnesium (C) is more preferably 0.2 to 10 μm, and further preferably 0.3 to 5 μm.
In addition, the average particle diameter of basic magnesium (C) is a median diameter (D50), and is specifically measured by the method described in the examples.

<Tackifying resin>
The rubber-based foamable resin composition of the present invention may contain a tackifying resin. By including the tackifier resin, the adhesion to the adherend surface of the foam can be enhanced.
The tackifying resin preferably has a softening point of 75 ° C or higher. Since the temperature at the time of manufacturing a foamable resin sheet can be made high that a softening point is 75 degreeC or more, the load of an extruder etc. can be reduced. Moreover, in this invention, since the amount of acrylonitrile components in a rubber-type resin is high, it exists in the tendency for the viscosity of a composition to rise, but moldability can be made favorable by mix | blending specific tackifying resin. The softening point of the tackifying resin is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, and preferably 130 ° C. or lower, more preferably 110 ° C. or lower. The softening point is a value measured according to JIS K 2207.
Examples of tackifier resins include petroleum resin-based tackifier resins, hydrogenated petroleum resin-based tackifier resins, rosin ester-based tackifier resins, rosin diol-based tackifier resins, terpene resins, phenol resins, xylene resins, coumarone resins, Examples thereof include ketone resins and modified resins thereof. Among these, rosin-based tackifier resins such as rosin ester-based tackifier resins and rosin diol-based tackifier resins are preferable from the viewpoint of improving the adhesion of the foam.

The content of the tackifying resin with respect to 100 parts by mass of the rubber-based resin is preferably 1 to 15 parts by mass. When the content of the tackifier resin with respect to 100 parts by mass of the rubber-based resin is 1 part by mass or more, the adhesiveness of the foam becomes good, and the water-stopping property can be secured. Further, when the amount is 15 parts by mass or less, the water pressure can be endured without excessively improving the flexibility, and the water stoppage is improved.
The content of the tackifying resin with respect to 100 parts by mass of the rubber-based resin is preferably 2 to 12 parts by mass, more preferably 3 to 8 parts by mass, from the viewpoint of ensuring adhesion and water-stopping property.

<Carbon black>
The rubber-based foamable resin composition of the present invention may contain carbon black.
Carbon black preferably has an iodine adsorption amount of 20 mg / g or more and a DBP adsorption amount of 60 mL / 100 g or more. The iodine adsorption amount is a physical property value that is an indicator of the specific surface area of carbon black, and the DBP adsorption amount (dibutyl phthalate adsorption amount) is a physical property value that is an indicator of the degree of carbon black particle linking and aggregation.
When the iodine adsorption amount is 20 mg / g or more, the adhesiveness of the foam tends to be good. The iodine adsorption amount is preferably 30 mg / g or more, more preferably 35 mg / g or more, from the viewpoint of improving the adhesion of the foam. The iodine adsorption amount is preferably 150 mg / g or less, more preferably 100 mg / g or less.
There exists a tendency for the adhesiveness of a foam to become it favorable that DBP adsorption amount is 60 mL / 100g or more. The DBP adsorption amount is preferably 65 mL / 100 g or more, more preferably 70 mL / 100 g or more, from the viewpoint of improving the adhesion of the foam. The DBP adsorption amount is preferably 150 mg / g or less.
The iodine adsorption amount can be determined according to JIS K6217-1, and the DBP adsorption amount can be determined according to JIS K6217-4.

The content of carbon black in the foam of the present invention is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the rubber-based resin. When it is 1 part by mass or more, the dimensional change of the foam over time hardly occurs. That is, long-term storage stability is good. When the amount is 15 parts by mass or less, the adhesiveness of the foam is improved. From the viewpoint of improving the long-term storage stability and adhesion of the foam, the carbon black is preferably 4 to 15 parts by mass, more preferably 4 to 12 parts by mass with respect to 100 parts by mass of the rubber-based resin. Yes, more preferably 5 to 11 parts by mass.
The average particle size of the carbon black of the present invention is preferably 15 to 70 nm, more preferably 20 to 50 nm.
When the average particle size is 15 nm or more, the foam moldability is good, and when it is 70 nm or less, the adhesiveness of the foam is good.
The average particle diameter of carbon black can be determined by measuring the diameter of the particles with a transmission electron microscope and calculating the average value.

<Additives>
The rubber-based foamable resin composition of the present invention may contain additives other than those described above. Examples of the additive include a flame retardant, an antioxidant, a filler other than the carbon black, a pigment, a colorant, a fungicide, a foaming aid, and a flame retardant aid. In these, it is preferable to use antioxidant.
Examples of the antioxidant include a phenolic antioxidant and a sulfurous antioxidant. Examples of phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2-tert- Butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ] Etc. are mentioned. These phenolic antioxidants may be used alone or in combination of two or more.
Examples of the sulfur-based antioxidant include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythrityltetrakis (3-laurylthiopropionate), and the like. These sulfur-based antioxidants may be used alone or in combination of two or more.
Further, the antioxidant may be used in combination with a phenol-based antioxidant and a sulfur-based antioxidant. 0.1-10 mass parts is preferable with respect to 100 mass parts of rubber-type resin, and, as for content of antioxidant, 0.2-5 mass parts is more preferable.
Examples of the filler include talc, calcium carbonate, bentonite, fumed silica, aluminum silicate, acetylene black, and aluminum powder.
These additives may be used individually by 1 type, and may be used in combination of 2 or more type.

<Rubber resin closed cell foam>
The rubber-based resin closed cell foam of the present invention is obtained by foaming a rubber-based foamable resin composition.
The rubber-based resin closed cell foam of the present invention has a closed cell ratio of 70% or more from the viewpoint of obtaining sufficient water-stopping property. Open bubbles may be included in some of the bubbles. In the present invention, if the closed cell ratio of the foam is preferably from 70 to 100%, more preferably from 80 to 100%, still more preferably from 85 to 100%, and even more preferably from 90 to 100%, sufficient stopping is achieved. Aqueous can be obtained.

In addition, the closed cell rate in this invention says what was measured in the following ways.
First, a test piece having a flat square shape with a side of 5 cm and a constant thickness is cut out from the foam. Then, the thickness of the test piece is measured to calculate the apparent volume V ₁ of the test piece, and the weight W _{1 of the} test piece is measured.
Next, the volume V ₂ occupied by the bubbles is calculated based on the following formula. The density of the resin constituting the test piece is ρg / cm ³ .
Volume occupied by bubbles V ₂ = V ₁ −W ₁ / ρ
Subsequently, the test piece is submerged in distilled water at 23 ° C. to a depth of 100 mm from the water surface, and a pressure of 15 kPa is applied to the test piece over 3 minutes. Thereafter, the test piece is taken out of the water, the water adhering to the surface of the test piece is removed, the weight W _{2 of the} test piece is measured, and the open cell rate F ₁ and the closed cell rate F ₂ are calculated based on the following formulas. To do.
Open cell ratio F ₁ (%) = 100 × (W ₂ −W ₁ ) / V ₂
Closed cell ratio F ₂ (%) = 100−F ₁

From the viewpoint of improving the flexibility of the foam, the apparent density of the foam is preferably 20 to 100 kg / m ³ , more preferably 20 to 75 kg / m ³ , still more preferably 25 to 55 kg / m ³ , and more More preferably, it is 25-45 kg / m < ³ >.

  The thickness of the foam is appropriately selected depending on the intended use and is not particularly limited, but is preferably 1 to 15 mm, more preferably 2 to 10 mm, and further preferably 4 to 10 mm. If the thickness is less than 1 mm, the foam is too soft to handle, and if it exceeds 15 mm, deformation tends to occur due to the weight of the foam itself.

  The use of the foam of the present invention is not particularly limited, but it can be suitably used as a waterproof seal material that fills gaps in various structures and prevents water from entering in various fields such as architecture, electronics, and vehicles. . The water-stop sealing material may be composed only of the foam of the present invention, or a thermoplastic resin such as polyethylene, polypropylene, vinyl acetate resin (polyvinyl acetate), vinyl chloride resin (polyvinyl chloride), or vinylidene chloride resin. A film made mainly of (polyvinylidene chloride) or the like may be laminated. By laminating, the smoothness of the surface can be improved, and as a result, flexibility and adhesion can be improved. Moreover, you may give the thin film of the low polarity molecule | numerator which contains a silicon | silicone and a fluorine in the molecular structure from a viewpoint of improving a water stop property to a foam.

<Method for producing rubber-based resin closed cell foam>
What is necessary is just to manufacture the rubber-type resin closed cell foam of this invention by heating the above-mentioned rubber-type foamable resin composition inside a heating apparatus, and making it foam.
Specifically, rubber obtained by blending and kneading a rubber-based resin, azodicarbonamide (B), basic magnesium (C) and, if necessary, a tackifying resin, carbon black, and other additives. A method of preparing a rubber-based foamable resin sheet by molding a sheet-based foamable resin composition into a sheet shape, and then crosslinking it with ionizing radiation, etc., and then heating and foaming in a heating apparatus such as a heating furnace or oven It is preferable to manufacture by.
[Method for producing rubber-based foamable resin sheet]
As a method for producing a rubber-based foamable resin sheet, for example, after kneading a rubber-based foamable resin composition using a kneader such as a Banbury mixer or a pressure kneader, an extruder, a calendar, a conveyor belt casting, etc. The method of manufacturing a rubber-type foamable resin sheet by extruding continuously is mentioned.

[Method of crosslinking rubber-based foamable resin sheet]
Next, examples of the crosslinking method of the rubber-based foamable resin sheet include crosslinking with ionizing radiation, crosslinking with an organic peroxide, and the like.
In the case of crosslinking with ionizing radiation, examples of the ionizing radiation include light, γ-rays, and electron beams. The irradiation amount of ionizing radiation is preferably 0.5 to 10 Mrad, and more preferably 0.7 to 5.0 Mrad.
When crosslinking is performed by ionizing radiation, a sheet of rubber-based resin closed cell foam having a small diameter and uniform bubbles can be obtained. Such a rubber-based resin closed cell foam sheet having uniform bubbles with a small diameter is excellent in water-stopping property because the surface is smooth, the contact area with the adherend surface is increased, and the adhesion is improved. .
In the case of crosslinking with an organic peroxide, examples of the organic peroxide include diisopropylbenzene hydroperoxide, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, t-butyl perbenzoate, cumyl hydroperoxide, t -Butyl hydroperoxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylhexane, n-butyl-4,4-di (t-butylperoxy) valerate, α, α ' -Bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, t-butylperoxycumene and the like.
0.05-10 mass parts is preferable with respect to 100 mass parts of rubber-type resins, and, as for the compounding quantity of an organic peroxide, 0.1-7 mass parts is more preferable.

[Method of foaming rubber-based foamable resin sheet]
Examples of the method for foaming the rubber-based foamable resin sheet include a batch system such as an oven, and a continuous foaming system in which the foamable resin sheet is formed into a long sheet shape and continuously passed through a heating furnace. The heating temperature is preferably 200 to 320 ° C, more preferably 250 to 300 ° C.

Examples The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
The materials used in the following examples and comparative examples are as follows.
(1) Acrylonitrile-butadiene rubber (NBR)
Product name “Nipol DL101L” manufactured by Nippon Zeon Co., Ltd.
Density: 1.00 g / cm ³ (solid)
Acrylonitrile component content: 42.5% by mass
Sulfur content: 1,500 mass ppm Measurement method: ICP-AES
(2) Liquid acrylonitrile-butadiene rubber Nippon Zeon Co., Ltd., trade name “Nipol 1312”
Acrylonitrile component content: 32% by mass
Sulfur content: 20,000 ppm by mass Measuring method: ICP-AES
(3) Phenol antioxidant (powder)
Product name “Irganox 1010” manufactured by Ciba Japan
(4) Sulfur-based antioxidant “NOCRACK 400” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd., dilauryl thiodipropionate (5) carbon black “# 60” manufactured by Asahi Carbon Co., Ltd.
Iodine adsorption amount 43mg / g, DBP adsorption amount 114mL / 100g
Average particle size 45nm
(6) Foaming agent Azodicarbonamide Trade name “SO-L” manufactured by Otsuka Chemical Co., Ltd., decomposition temperature: 197 ° C.
(7) Basic magnesium manufactured by Wako Pure Chemical Industries, Ltd. Magnesium oxide Particle size: 0.7 μm
Wako Pure Chemical Industries, Ltd. Magnesium hydroxide Particle size: 0.6μm
The average particle diameter of basic magnesium was measured by a laser diffraction particle size distribution analyzer “HELOS (H2731)” (manufactured by Sympatec) at a median diameter (D50) measured at a dispersion pressure of 2.00 bar and a pulling pressure of 72.00 mbar. It is.
(8) Tackifying resin Rosin ester-based tackifying resin “KE359” manufactured by Arakawa Chemical Industries, Ltd.
Melt viscosity: 65 mPa / s (200 ° C.)
Softening point: 99 ° C
Hydroxyl value: 40 mgKOH / g

Example 1
Each component was blended according to the description in Table 1 and kneaded with a pressure kneader. Next, the rubber-based foamable resin composition is supplied to an extruder and melt-kneaded, and then the molten rubber-based foamable resin composition is extruded from the extruder at an extrusion speed of 50 kg / hour. A rubber-based foamable resin sheet having a thickness of 1.6 mm was produced. Subsequently, the rubber-based foamable resin sheet was cross-linked by irradiating 1.8 Mrad of ionizing radiation at an acceleration voltage of 450 keV on both sides of the rubber-type foamable resin sheet (the cross-linked sheet was a rubber-type foamable resin sheet). (1)).
And the rubber-type foaming resin sheet (1) was supplied in the heating furnace, and it was made to foam by heating at 270 degreeC, and the rubber-type resin closed cell foam of thickness 5mm was obtained.
The rubber-based foamable resin sheet (1) was evaluated for the contamination degree of the heating furnace shown below. Moreover, with respect to the rubber-based resin closed cell foam, the thickness of the foam (mm), the apparent density (kg / m ³ ), the closed cell rate (%), the peel adhesion (N / 25 mm), the water stoppage Evaluation on the test (kPa) was performed. The results are shown in Table 1.

Example 2, Comparative Examples 1-2
A rubber-based foamable resin composition and a rubber-based resin closed cell foam were produced in the same manner as in Example 1 except that the formulation was changed as shown in Table 1, and the following evaluation was performed. The results are shown in Table 1.

<Evaluation>
(1) Apparent density It measured based on JISK7222.
(2) Closed cell ratio The closed cell ratio (%) was measured based on the method described above.
(3) Peel adhesion The obtained foam was cut into a width of 25 mm and a length of 300 mm, attached to an acrylic plate, compressed by 30% with a stainless steel plate, and left at 23 ° C. for 24 hours. After 24 hours, the compression was released, and the peel adhesion (N / 25 mm) in the 180 ° direction was measured.
The peel adhesion is preferably 0.7 to 10 N / 25 mm, and more preferably 1.0 to 10 N / 25 mm.
(4) Water-stop test The obtained foam was processed into a ring shape having an inner diameter of 40 mm and an outer diameter of 60 mm (seal width 10 mm), compressed by 30% with a 10 mm-thick acrylic plate, and left at 23 ° C. for 24 hours. . After 24 hours, with the compressibility maintained, tap water was filled inside the ring-shaped sealing material, and water pressure was applied to the inside of the ring-shaped sealing material to determine the presence or absence of water leakage. The water pressure is maintained at 5 kPa for 5 minutes, then the pressure is increased by 5 kPa, maintained for 5 minutes for each pressure, the pressure is increased until the water inside the ring-shaped sealing material leaks, and the maximum pressure is increased. Asked.
(5) Evaluation of heating furnace contamination The rubber-based resin foam sheet was continuously passed through the heating furnace for 12 hours. The temperature in the heating furnace was set to 270 ° C. Evaluation of heating furnace contamination was performed based on the following evaluations 1 and 2.
(Evaluation 1) The weight of the deposit on the most dirty part in the heating furnace was measured and evaluated as follows.
When the deposit in the area of 20 mm x 100 mm is less than 60 g ... 1 point When the deposit in the area of 20 mm x 100 mm is 60 g or more ... 0 point (Evaluation 2) Sheet contamination of the deposit in the heating furnace The impact was evaluated as follows.
When the deposits in the heating furnace do not transfer to the sheet ... 1 point When the deposits in the heating furnace transfer to the sheet ... 0 points (overall evaluation)
Evaluation criteria for heating furnace contamination A. ・ The total score of Evaluation 1 and Evaluation 2 is 2 points.
B ・ ・ The total score of Evaluation 1 and Evaluation 2 is 1 point.
C ・ ・ Total score of Evaluation 1 and Evaluation 2 is 0

  As is clear from the results in Table 1, the rubber-based foamable resin composition of the present invention is less likely to contaminate the heating furnace and has excellent foam physical properties such as foam thickness, apparent density, and peel adhesion. I understood that.

Claims (8)

  0.05 to 5 parts by mass of magnesium oxide and hydroxide based on 100 parts by mass of the rubber resin (A), azodicarbonamide (B), and the rubber resin (A) containing 35% by mass or more of an acrylonitrile component A rubber-based foamable resin composition containing at least one basic magnesium (C) selected from magnesium.   2. The rubber-based foamable resin composition according to claim 1, wherein in the foamable resin composition, azodicarbonamide (B) is blended in an amount of 5 to 25 parts by mass with respect to 100 parts by mass of the rubber-based resin (A). object.   The rubber-based foamable resin composition according to claim 1 or 2, wherein the basic magnesium (C) has an average particle size of 0.1 to 15 µm.   A rubber-based resin closed cell foam having a closed cell ratio of 70% or more obtained by foaming the rubber-based foamable resin composition according to any one of claims 1 to 3. The rubber-based resin closed-cell foam according to claim 4, having an apparent density of 20 to 100 kg / m ³ .   The rubber-based resin closed cell foam according to claim 4 or 5, wherein the closed cell rate is 80 to 100%.   The water-stop sealing material which consists of a rubber-type resin closed cell foam of any one of Claims 4-6.   It is a manufacturing method of the rubber-type resin closed-cell foam of any one of Claims 4-6, Comprising: The rubber-type resin independent made to heat and foam the said rubber-type foamable resin composition inside a heating apparatus. A method for producing a cellular foam.