JP2022063319A - Master batch for polyolefin crosslinked foam, polyolefin crosslinked foam, and manufacturing method of polyolefin crosslinked foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefin crosslinked foam low in remaining ammonium concentration, capable of preventing contamination or corrosion due to ammonia, and suitable for impact cushioning applications such as a floor material or a wall material of house, a joint filling material of building, an automotive interior member, a member for package or the like.

SOLUTION: There is provided a polyolefin crosslinked foam having density of 20 to 160 kg/m³, ammonia concentration of 0 ppm to 100 ppm, and glass haze degree of 5% or less, obtained by a mixed article containing a master batch for polyolefin crosslinked foam containing an ethylene vinyl acetate copolymer with vinyl acetate content of 18 wt.% or more and/or an ethylene-propylene-diene three dimensional copolymer with Mooney viscosity (ML1+4, 100°C) of 20 to 40, and sodium bicarbonate and p,p'-oxybisbenzenesulfonyl hydrazide as foaming agents, a polyolefin resin, and a crosslinking agent.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a masterbatch for a polyolefin-based crosslinked foam, a polyolefin-based crosslinked foam, and a method for producing a polyolefin-based crosslinked foam.

Polyolefin-based crosslinked foam is durable, and has excellent chemical resistance and weather resistance, so it is used for shock absorbing applications such as flooring and wall materials for houses, joint materials for buildings, interior materials for automobiles, and packaging materials. Widely used.
The mainstream of foaming of a polyolefin-based crosslinked foam is thermal foaming using a pyrolysis-type foaming agent whose cost and thickness of the foam can be easily controlled. As the pyrolytic foaming agent, an azodicarbonamide (ADCA) -based foaming agent having good workability is generally used (Patent Document 1). The azodicarbonamide-based foaming agent has a large amount of gas generated by thermal decomposition, and a highly foamable polyolefin-based crosslinked foam can be obtained. Further, since the decomposition temperature of the azodicarbonamide-based foaming agent is around 200 ° C., which is higher than the melting point of the polyolefin-based resin, azodicarbonamide-based foaming is performed even if kneading with the polyolefin-based resin is performed near the melting point of the polyolefin-based resin. There is no risk of the agent decomposing, the viscosity during kneading can be lowered, and the kneading work is easy.

However, since the azodicarbonamide-based foaming agent generates ammonia as a decomposition residue, when a polyolefin-based crosslinked foam using the azodicarbonamide-based foaming agent is used as a cushioning member for packaging, electronic devices, medical parts, etc. There is a problem that the interior materials of automobiles, head lamps, etc. are contaminated and corroded by the ammonia remaining in the polyolefin-based crosslinked foam. For example, headlamps have a problem of being fogged by ammonia.

In order to suppress the influence of ammonia remaining on the polyolefin-based crosslinked foam, a polyolefin-based crosslinked foam containing an ammonia adsorbent to reduce the ammonia concentration has been proposed (Patent Document 2).
However, since the polyolefin-based crosslinked foam has a closed cell structure, only the ammonia adsorbent existing on the surface of the foam is effective, and the ammonia adsorbent buried inside the foam cannot exert a sufficient effect. Go.

Further, it has been studied to use baking soda (sodium hydrogen carbonate) as a pyrolytic foaming agent without using an azodicarbonamide (ADCA) -based foaming agent or an ammonia adsorbent.
However, since the baking soda begins to thermally decompose at around 100 ° C., which is lower than the melting point of the polyolefin-based resin, in order to prevent the baking soda from separately decomposing during kneading with the polyolefin-based resin, kneading should be performed at a temperature higher than the melting point of the polyolefin-based resin. Must be done at low temperatures below 100 ° C. As a result, there is a problem that the viscosity at the time of kneading becomes high and the kneading time becomes long. Further, if the kneading time performed at a temperature lower than 100 ° C. is shortened in order to improve the efficiency of the work, the kneading is insufficient and foaming defects occur when the polyolefin resin is foamed.

Japanese Unexamined Patent Publication No. 11-228725 Japanese Unexamined Patent Publication No. 2012-131848

The present invention has been made in view of the above points, and is a master batch for a polyolefin-based crosslinked foam, a polyolefin-based crosslinked foam, and a polyolefin-based crosslink that can reduce the ammonia concentration of the polyolefin-based crosslinked foam and can be efficiently produced. An object of the present invention is to provide a method for producing a foam.

The invention of claim 1 relates to an ethylene-vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more and / or an ethylene-propylene-diene ternary copolymer having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40. , A master batch for a polyolefin-based crosslinked foam containing baking soda and p, p'-oxybisbenzenesulfonyl hydrazide as a foaming agent.

The invention of claim 2 is characterized in that, in claim 1, the foaming agent has a larger amount of p, p'-oxybisbenzenesulfonyl hydrazide than the amount of baking soda.

The invention of claim 3 is characterized in that, in claim 2, the foaming agent is p, p'-oxybisbenzenesulfonyl hydrazide amount / amount of baking soda = 5.5 / 4.5 to 77/23. And.

The invention of claim 4 is characterized in that, in any one of claims 1 to 3, the particle size of the foaming agent is 8 to 30 μm.

The invention of claim 5 is a polyolefin-based crosslinked foam obtained from a master batch for a polyolefin-based crosslinked foam according to any one of claims 1 to 4 and a kneaded product containing a polyolefin-based resin and a cross-linking agent. It is a polyolefin-based crosslinked foam having a density of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less.

The invention of claim 6 is characterized in that, in claim 5, the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.

The invention according to claim 7 is any one of claims 1 to 4 in a method for producing a polyolefin-based crosslinked foam having a density of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less. It is characterized in that the masterbatch for a polyolefin-based crosslinked foam according to item 1 and a kneaded product containing a polyolefin-based resin and a cross-linking agent are foamed at a foaming ratio of 6 to 50 times by one-step foaming or two-step foaming.

The invention of claim 8 is characterized in that, in claim 7, the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.

In the present invention, the base material of the master batch for a polyolefin-based crosslinked foam is an ethylene vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more and / or ethylene having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40. -Since it is composed of a propylene-diene ternary copolymer, the base metal can be softened at a temperature lower than the pyrolysis temperature of baking soda as a foaming agent and p, p'-oxybisbenzenesulfonyl hydrazide, and the base metal and foaming can be performed. Baking soda as an agent and p, p'-oxybisbenzenesulfonyl hydrazide can be prevented from thermally decomposing and can be kneaded efficiently. The pyrolysis temperature of the baking soda has a pyrolysis peak at 140 to 170 ° C., and the pyrolysis temperature of p, p'-oxybisbenzenesulfonyl hydrazide has a pyrolysis peak at 155 to 165 ° C.

By using a masterbatch containing a foaming agent, the kneading of the polyolefin resin and the foaming agent can be replaced with the kneading of the polyolefin resin and the masterbatch during the production of the polyolefin-based crosslinked foam. Kneading the masterbatch containing the foaming agent and the polyolefin resin is easier than kneading the foaming agent directly with the polyolefin resin, and has good kneading and kneading time that suppresses thermal decomposition of the foaming agent. It becomes possible to obtain a polyolefin-based crosslinked foam having a good foaming state.

Baking soda has a decomposition gas of carbon dioxide and a decomposition residue of sodium carbonate, while p, p'-oxybisbenzenesulfonyl hydrazide has a decomposition gas of nitrogen gas and a decomposition residue of polydithiophenyl ether and polythiophenylbenzenesulfonyl. It is an ether, and neither produces ammonia as a decomposition residue. Therefore, the polyolefin-based crosslinked foam using the masterbatch for the polyolefin-based crosslinked foam of the present invention can have a low ammonia concentration of 0 to 100 ppm, and can prevent contamination and corrosion by residual ammonia. can.

It is a table which shows the compounding of the example and the comparative example of a masterbatch, and the presence or absence of thermal decomposition. It is a table which shows the compounding of the polyolefin resin and the masterbatch, the measurement result of the physical property, etc. about the Example and the comparative example of the polyolefin-based crosslinked foam.

The polyolefin-based crosslinked foam of the present invention is suitable for shock absorbing applications such as floor materials and wall materials of houses, joint materials of buildings, interior materials of automobiles, and packing materials, and has a density (JIS K 6767 compliant). 20 to 160 kg / m ³ , the ammonia concentration is 0 ppm to 100 ppm, and the glass haze (based on ISO6452) is 5% or less. The ammonia concentration was measured by putting 0.1 g of a sample into a round bottom flask 500 cc, leaving it in an oven at 80 ° C. for 2 hours, taking it out and allowing it to cool, and measuring it with an ammonia detector tube (manufactured by Gastec).

When the polyolefin-based crosslinked foam is used, for example, as a cushioning member for packaging, if the density of the polyolefin-based crosslinked foam is too low, the foam becomes too flexible and the shape cannot be maintained, which is not preferable as a cushioning material. On the other hand, if the density is too high, the foam becomes hard and flexible, which is not preferable as a cushioning material. Therefore, the density is preferably 20 to 160 kg / m ³ .
If the ammonia concentration of the polyolefin-based crosslinked foam is too high, problems of contamination and corrosion of the packaged product will increase. Therefore, the ammonia concentration is preferably 0 ppm to 100 ppm.
If the glass haze of the polyolefin-based crosslinked foam is too high, fogging is likely to occur in the packed headlamps, so the glass haze is preferably 5% or less.

Polyolefin-based crosslinked foams having a density (JIS K 6767 compliant) of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze (ISO6452 compliant) of 5% or less are the master batches for polyolefin-based crosslinked foams. , Obtained from a kneaded product containing a polyolefin resin and a cross-linking agent.

The master batch for polyolefin-based crosslinked foams is an ethylene-vinyl acetate copolymer (EVA) having a vinyl acetate content of 18% by weight or more and / or an ethylene-propylene-diene having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40. It is made of a ternary copolymer (EPDM) as a base material and contains sodium bicarbonate (sodium hydrogen carbonate) and p, p'-oxybisbenzenesulfonyl hydrazide (OBSH) as a foaming agent.

In the ethylene-vinyl acetate copolymer, when the vinyl acetate content is less than 18% by weight, the melting point of the resin is high and the kneading temperature is high, so that the foaming agent is decomposed. A more preferred range of vinyl acetate content is 20-28% by weight. The vinyl acetate content is a value measured according to JIS K 6924-1. The ethylene-vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more has a melting point of 93 ° C. or lower, and has a pyrolysis temperature of 140 to 170 ° C. and a thermal decomposition temperature of p, p'-oxybisbenzenesulfonyl hydrazide. Is lower than 155 to 165 ° C.

Ethylene-propylene-diene ternary copolymers having Mooney viscosity (ML1 + 4, 100 ° C.) of 20-40 have low viscosities at temperatures lower than the pyrolysis temperature of baking soda and p, p'-oxybisbenzenesulfonyl hydrazide. Is. Mooney viscosity is a value measured according to JIS K 6300.

The ethylene-vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more and the ethylene-propylene-diene ternary copolymer having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40 can be used alone or. Both are used together.

As the foaming agent, baking soda and p, p'-oxybisbenzenesulfonyl hydrazide are used in combination. Baking soda alone tends to cause shrinkage after foaming of the polyolefin-based crosslinked foam, while p, p'-oxybisbenzenesulfonyl hydrazide alone tends to cause insufficient foaming. By using baking soda and p, p'-oxybisbenzenesulfonyl hydrazide in combination, it is possible to prevent shrinkage after foaming and insufficient foaming. As for the amount of baking soda (parts by weight) and the amount of p, p'-oxybisbenzenesulfonyl hydrazide (parts by weight), it is preferable that the amount of p, p'-oxybisbenzenesulfonyl hydrazide is larger than the amount of baking soda. By increasing the amount of p, p'-oxybisbenzenesulfonyl hydrazide rather than the amount of baking soda, nitrogen gas, which is the decomposition gas of p, p'-oxybisbenzenesulfonyl hydrazide, is compared with carbon dioxide gas, which is the decomposition gas of baking soda. Can be increased. After foam molding, it is held not only by carbon dioxide gas but also by nitrogen gas having a low diffusion coefficient, so that rapid shrinkage and deformation after foam molding can be suppressed. More preferably, the amount of p, p'-oxybisbenzenesulfonyl hydrazide (parts by weight) / the amount of baking soda (parts by weight) = 5.5 / 4.5 to 77/23.

Baking soda and p, p'-oxybisbenzenesulfonyl hydrazide are each thermally decomposed by heating during the production of the polyolefin-based crosslinked foam to generate gas, and the polyolefin-based resin is foamed. Baking soda generates carbon dioxide gas by thermal decomposition at 140 ° C. to 170 ° C., and produces sodium carbonate as a decomposition residue. On the other hand, p, p'-oxybisbenzenesulfonyl hydrazide generates nitrogen gas by thermal decomposition at 155 ° C to 165 ° C, and polydithiophenyl ether and polythiophenylbenzenesulfonyl ether are produced as decomposition residues. Since neither baking soda nor p, p'-oxybisbenzenesulfonyl hydrazide produces ammonia as a decomposition residue, the ammonia concentration of the polyolefin crosslinked foam can be reduced.
In addition, the difference in the thermal decomposition temperature range between the baking soda and p, p'-oxybisbenzenesulfonyl hydrazide is close to ± 15 ° C, and both can be pyrolyzed in the range of 155 ° C to 165 ° C, so foaming occurs. It is well-balanced and preferable as a foaming agent to be mixed.

Boso and p, p'-oxybisbenzenesulfonyl hydrazide as a foaming agent have an ethylene vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more as a base material and / or a Mooney viscosity (ML1 + 4, 100 ° C.). When kneading with 20 to 40 ethylene-propylene-diene ternary copolymer (EPDM), the particle size is preferably 8 to 30 μm in order to improve the dispersion of the foaming agent.

The masterbatch for a polyolefin-based crosslinked foam is produced by kneading the base material and the foaming agent with a kneader at a temperature lower than the decomposition temperature of the foaming agent. The kneading temperature is preferably 95 to 135 ° C, more preferably 100 to 125 ° C. The masterbatch for a polyolefin-based crosslinked foam is preferably kneaded, cooled, and then cut into pellets with a pelletizer so as to be easy to handle during the production of the polyolefin-based crosslinked foam. The particle size of the pellet is preferably 3 to 5 mm.

The amount of the foaming agent in the master batch for a polyolefin-based crosslinked foam is preferably 40 to 250 parts by weight, more preferably 70 to 150 parts by weight, based on 100 parts by weight of the base material. When the preferable amount of the foaming agent is converted into the weight% of the foaming agent in the total weight of the masterbatch for the polyolefin-based crosslinked foam, it is 25 to 70%, more preferably 30 to 60%. If the amount of the foaming agent is too small, the foam becomes hard and has an unfavorable result as a cushioning material in terms of flexibility. It becomes.

The amount of the masterbatch for the polyolefin-based crosslinked foam in producing the polyolefin-based crosslinked foam is preferably 7 to 80 parts by weight, more preferably 10 to 60 parts by weight, based on 100 parts by weight of the polyolefin-based resin. The content of the foaming agent is determined according to the foaming ratio of the polyolefin-based crosslinked foam.

Polyethylene-based resins include low-density, medium-density, high-density, linear low-density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, and ethylene. Examples include copolymers with methyl, ethyl, propyl or butyl acrylic acid esters (content of this ester; within 45 mol%), or those chlorinated to a chlorine content of 60% by weight. can. Particularly low density polyethylene is preferred.

Examples of the cross-linking agent include organic peroxides such as dicumyl peroxide, 2,5-dimethyl-2,5-bis-tersary butylperoxyhexane, and 1,3-bis-tershally peroxy-isopropylbenzene. be able to. The amount of the cross-linking agent is preferably 1.0 to 5.0 parts by weight with respect to 100 parts by weight of the polyolefin resin.

The kneaded product contains an auxiliary agent as appropriate. Examples of the auxiliary agent include foaming aids, nucleating agents, other inorganic fillers, colorants and the like. Examples of the effervescence aid include metal oxides such as zinc oxide and lead oxide, lower or higher fatty acids, and metal salts thereof. Examples of the nucleating agent include calcium bicarbonate. Examples of other inorganic fillers include conductive carbon black.

In the production of the polyolefin-based crosslinked resin foam, a masterbatch for a polyolefin-based crosslinked foam, a kneaded product of a foamable resin composition containing a polyolefin resin, a crosslinking agent and an appropriate auxiliary agent is first-stage foamed or two-stage foamed. Do by.

The kneading of the foamable resin composition is carried out using a kneader or the like at a temperature lower than the thermal decomposition temperature of the foaming agent contained in the masterbatch for a polyolefin-based crosslinked foam.
In the one-stage foaming, a kneaded product of the foamable resin composition is filled in a foaming mold, heated and pressed to decompose the foaming agent, and then the foaming mold is opened to foam, thereby foaming a desired polyolefin-based crosslinked resin. Get the body.
In the two-stage foaming, the kneaded product of the foamable resin composition is filled in a primary foaming mold and heated and pressed to form a primary foam, and then the inner surface shape is larger than the outer shape of the primary foam. The primary foam is housed in a large secondary foam type and heated under normal pressure to cause secondary foaming to obtain a desired polyolefin-based crosslinked foam. In the two-stage foaming, a foam having a higher foaming ratio than the one-stage foaming can be obtained.

The heating and pressurization in the case of one-stage foaming differ depending on the foaming ratio, and examples thereof include a heating temperature of 130 to 170 ° C., a heating time of 30 to 60 minutes, and a pressure of about 5 to 35 Pa.
The heating and pressurization in the case of two-stage foaming differ depending on the foaming ratio, but for example, the heating temperature at the time of primary foaming is 100 to 150 ° C., the heating time is 30 to 60 minutes, the pressure is about 5 to 35 Pa, and the heating at the time of secondary foaming. The temperature is 140 to 170 ° C. and the heating time is about 25 to 180 minutes.

The foaming ratio is preferably 6 to 50 times in both the one-stage foaming and the two-stage foaming. The foaming ratio is a value calculated by the following formula 1 with the unfoamed resin as 1000 kg / m ³ .
1000kg / m ³ (unfoamed) ÷ measured foam density (kg / m ³ ) (Equation 1)
The measured foam density value is a value measured in accordance with JIS K 6767.
If the expansion ratio is too low, the foam becomes too flexible and the shape cannot be maintained, which is not preferable as a cushioning material. On the contrary, if it is too high, the foam becomes hard and becomes flexible, which is not preferable as a cushioning material. Further, the expansion ratio at the time of one-stage foaming and two-stage foaming is adjusted to be 6 to 50 times depending on the amount of the foaming agent contained in the masterbatch for the polyolefin-based crosslinked foam.

<Masterbatch>
Masterbatches (a) to (h) of Examples and Comparative Examples (i) to (l) were prepared with the formulation shown in FIG. The masterbatch was prepared by kneading the base material and the foaming agent at 100 ° C. for 25 minutes with a kneader. After kneading, 100 g of the product cured for 5 minutes is collected and heat-pressed at 70 ° C. to prepare a flat plate of 50 × 50 mm × 5 mm, and the density is measured by the following formula to determine whether the foaming agent is thermally decomposed. Judging.
Density = weight of flat plate / (length x width x thickness of flat plate)
If the density value is less than 1000 kg / m ³ , it is judged that the foaming agent has decomposed because it is foaming, and if the density value is 1000 kg / m ³ or more, it is not foamed, so the foaming agent is It was judged that it was not disassembled. In the evaluation column of thermal decomposition in FIG. 1, "◯" indicates the case where the foaming agent is not decomposed, while "x" indicates the case where the foaming agent is decomposed.

In Example (a), EVA (ethylene vinyl acetate copolymer) as a base material: VA value (vinyl acetate content) of 20% by weight, Ultrasen 638 manufactured by Tosoh Corporation by 100 parts by weight, and OBSH (p.) As a foaming agent. , P'-oxybisbenzenesulfonyl hydrazide): Neocerbon N # 5000 manufactured by Eiwa Kasei Kogyo Co., Ltd., 60 parts by weight with an average particle size of 15 μm, and baking soda: Cellmic 266 manufactured by Sankyo Kasei Co., Ltd., 40 weight with an average particle size of 12 μm. This is an example used. In Example (a), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (b), the amount of OBSH in Example (a) is 75 parts by weight, the amount of baking soda is 25 parts by weight, and the other examples are the same as in Example (a). In Example (b), the value of OBSH / baking soda is 75/25, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (c), EPDM (ethylene-propylene-diene ternary copolymer): Mooney viscosity (ML1 + 4, 100 ° C.) is 30, instead of EVA as the base material in Example (a), Mitsui Chemicals, Inc. 1035 is used, and the other examples are the same as in Example (a). In Example (c), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (d), the amount of OBSH in Example (c) is 75 parts by weight, the amount of baking soda is 25 parts by weight, and the other examples are the same as in Example (c). In Example (d), the value of OBSH / baking soda is 75/25, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (e), the base material of Example (a) is EVA (ethylene vinyl acetate copolymer): VA value (vinyl acetate content) 20% by weight, and Ultrasen 638 manufactured by Tosoh Corporation is 50 parts by weight. And EPDM (ethylene-propylene-diene ternary copolymer): Mooney viscosity (ML1 + 4, 100 ° C.) is 30, 50 parts by weight of 1035 manufactured by Mitsui Chemicals Co., Ltd. is used, and the others are the same as in Example (a). Is an example of. In Example (e), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (f), Cellmic S manufactured by Sankyo Kasei Co., Ltd. and an average particle size of 50 μm are used as the OBSH of Example (a), and the other examples are the same as in Example (a). In Example (f), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (g), N # 1000M manufactured by Eiwa Kasei Kogyo Co., Ltd. and an average particle size of 4 μm are used as the OBSH of Example (a), and the other examples are the same as in Example (a). In Example (g), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Example (h), EPDM (ethylene-propylene-diene ternary copolymer): Mooney viscosity (ML1 + 4, 100 ° C.) is 30, instead of EVA as the base material in Example (g), Mitsui Chemicals, Inc. 1035 is used, and the other examples are the same as in Example (g). In Example (h), the value of OBSH / baking soda is 6/4, there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

In Comparative Example (i), ADCA (azodicarbonamide): Panthren H7310 manufactured by Eiwa Kasei Kogyo Co., Ltd., 100 parts by weight of an average particle size of 15 μm was used as the foaming agent in Example (a), and neither OBSH nor baking soda was contained. This is an example. In Comparative Example (i), there is no thermal decomposition of the foaming agent, and the evaluation is “◯”.

Comparative Example (j) is an example in which 100 parts by weight of baking soda is used alone as the foaming agent in Example (c). In Comparative Example (j), there is thermal decomposition of the foaming agent, and the evaluation is “x”.

In Comparative Example (k), EPDM (ethylene-propylene-diene ternary copolymer): Mooney viscosity (ML1 + 4, 100 ° C.) of 10, JSR EP912P manufactured by JSR Corporation was used as the base material in Example (c). , Others are the same examples as in Example (c). In Comparative Example (k), there is thermal decomposition of the foaming agent, and the evaluation is “x”.

In Comparative Example (l), EVA (ethylene vinyl acetate copolymer): VA value (vinyl acetate content) of 15% by weight, Ultrasen 630 manufactured by Tosoh Corporation was used as the base material in Example (a), and the like. Is the same example as in Example (a). In Comparative Example (l), there is thermal decomposition of the foaming agent, and the evaluation is “x”.

<Polyolefin-based crosslinked foam>
Low-density polyethylene (LDPE): MFR2, density 0.924 kg / m ³ , product number UBE polyethylene F224C, manufactured by Ube-Maruzen Polyethylene Co., Ltd. is used as the polyolefin resin, and the master batches (a) to (i) are blended as shown in FIG. bottom. Further, a mixture containing 2.7 parts by weight of Kayaku Mill D-40C manufactured by Kayaku Akzo Corporation as a cross-linking agent (not shown in FIG. 2) was kneaded with a kneader with respect to 100 parts by weight of LDPE, and then kneaded with a roll. Effervescent resin compositions of Examples 1 to 9 and Comparative Examples 1 to 5 were obtained. Kneading was carried out at a temperature of 90 ° C. for 20 minutes using a 1 L kneader.

Using the foamable resin composition, polyolefin crosslinked foams were produced by one-step foaming in Examples 1, 2, 4, 5, 8 and 9 and Comparative Examples 1 to 5, and in Examples 3, 6 and 7. A polyolefin-based crosslinked foam was produced from two-stage foaming.
In the one-stage foaming, the foamable resin composition after kneading was filled in a foaming mold, heated under pressure, depressurized and foamed, and the polyolefin-based crosslinked foam was taken out from the foaming mold. The foam molding space has a length of 160 mm, a width of 160 mm, a depth of 33 mm, and a volume of 0.85 L. The filling amount of the foamable resin composition is 900 g, the pressure is 7 Pa, and the heating is 135 ° C. for 50 minutes.

In the two-stage foaming, the foamable resin composition after kneading is filled in a primary foaming mold, heated under pressure, depressurized and foamed, and then a primary foaming step of taking out the primary foam from the primary foaming mold is performed. The obtained primary foam was housed in a secondary foam type, and secondary foaming was performed by secondary heating under normal pressure to take out a polyolefin-based crosslinked foam from the secondary foam type.

The molding space of the primary foam type has a length of 160 mm, a width of 160 mm, a depth of 33 mm, and a volume of 0.85 L. The filling amount of the foamable resin composition is 900 g, the pressure is 7 Pa, and the heating is 130 ° C. for 50 minutes.
The molding space of the secondary foam type has a length of 300 mm, a width of 300 mm, a depth of 55 mm, and a volume of 1.5 L. Heating is at 150 ° C. for 50 minutes.

Density (JIS K 6767 compliant), foaming magnification, ammonia concentration, and glass haze (ISO6452 compliant) in each Example and each Comparative Example were measured. The measurement results are shown in FIG.

The foaming ratio was calculated by the above formula 1.
Ammonia concentration is coarse with a gastech detector tube (product number: 3M) that can measure 0.1 g of a sample in a round bottom flask, heat it in an oven at 80 ° C for 2 hours, and then measure 10 to 1000 ppm before it cools. After measuring each value, the ammonia concentration was measured with an accurate gas tech detector tube (product number: 3 L) capable of measuring less than 100 ppm.
The glass haze (fogging) was measured by heating the sample at 80 ° C. for 20 hours with the sample shielded by a glass plate, and measuring the degree of haze adhering to the glass plate by Nippon Denshoku Industries Co., Ltd. (product number: NDH-20H). ..
The overall evaluation is "○" when all the conditions of density 20 to 160 kg / m ³ , ammonia concentration 0 ppm to 100 ppm, and glass haze of 5% or less are satisfied. In the case of poor foaming, it was marked with "x".

Example 1 is an example in which the masterbatch (a) is 10 parts by weight with respect to 100 parts by weight of LDPE. Example 1 has a density of 93 kg / m ³ , a foaming magnification of 10.8 times, an ammonia concentration of 10 ppm, a glass haze of 0.4%, and a comprehensive evaluation of “◯”.

Example 2 is an example in which the masterbatch (a) is 30 parts by weight with respect to 100 parts by weight of LDPE. Example 2 has a density of 68 kg / m ³ , a foaming magnification of 14.7 times, an ammonia concentration of 15 ppm, a glass haze of 0.4%, and a comprehensive evaluation of “◯”.

Example 3 is an example in which the masterbatch (a) is 70 parts by weight with respect to 100 parts by weight of LDPE. Example 3 has a density of 24 kg / m ³ , a foaming magnification of 41.7 times, an ammonia concentration of 15 ppm, a glass haze of 0.6%, and a comprehensive evaluation of “◯”.

Example 4 is an example in which the masterbatch (b) is 10 parts by weight with respect to 100 parts by weight of LDPE. Example 4 has a density of 98 kg / m ³ , a foaming magnification of 10.2 times, an ammonia concentration of 40 ppm, a glass haze of 2.2%, and a comprehensive evaluation of “◯”.

Example 5 is an example in which the masterbatch (c) is 10 parts by weight with respect to 100 parts by weight of LDPE. Example 5 has a density of 100 kg / m ³ , a foaming ratio of 10 times, an ammonia concentration of 15 ppm, a glass haze of 0.2%, and a comprehensive evaluation of “◯”.

Example 6 is an example in which the masterbatch (c) is 30 parts by weight with respect to 100 parts by weight of LDPE. Example 6 has a density of 62 kg / m ³ , a foaming magnification of 16.1 times, an ammonia concentration of 15 ppm, a glass haze of 0.3%, and a comprehensive evaluation of “◯”.

Example 7 is an example in which the masterbatch (c) is 70 parts by weight with respect to 100 parts by weight of LDPE. Example 7 has a density of 29 kg / m ³ , a foaming magnification of 34.5 times, an ammonia concentration of 20 ppm, a glass haze of 0.7%, and a comprehensive evaluation of “◯”.

Example 8 is an example in which the masterbatch (d) is 10 parts by weight with respect to 100 parts by weight of LDPE. Example 8 has a density of 107 kg / m ³ , a foaming magnification of 9.3 times, an ammonia concentration of 45 ppm, a glass haze of 2.9%, and a comprehensive evaluation of “◯”.

Example 9 is an example in which the masterbatch (g) is 10 parts by weight with respect to 100 parts by weight of LDPE. Example 9 has a density of 95 kg / m ³ , a foaming magnification of 10.5 times, an ammonia concentration of 10 ppm, a glass haze of 0.3%, and a comprehensive evaluation of “◯”.

Comparative Example 1 is an example in which the masterbatch (a) is 4 parts by weight with respect to 100 parts by weight of LDPE. Comparative Example 1 has a density of 900 kg / m ³ , a foaming ratio of 1.1 times, and a comprehensive evaluation of “x” without foaming. Ammonia concentration and glass haze were not measured because they did not foam. The master batch (a) is one of the master batches of the examples, but the density is high because the blending amount is small.

Comparative Example 2 is an example in which the masterbatch (f) is 10 parts by weight with respect to 100 parts by weight of LDPE. Comparative Example 2 has poor foaming, a density of 230 kg / m ³ , a foaming magnification of 4.3 times, and a comprehensive evaluation of “x”. Ammonia concentration and glass haze were not measured due to poor foaming. The master batch (f) is one of the master batches of the examples, but the average particle size of OBSH is as large as 50 μm, so that foaming defects occur.

Comparative Example 3 is an example in which the masterbatch (h) is 10 parts by weight with respect to 100 parts by weight of LDPE. Comparative Example 3 has poor foaming, a density of 200 kg / m ³ , a foaming magnification of 5.0 times, and a comprehensive evaluation of “x”. Ammonia concentration and glass haze were not measured due to poor foaming. The master batch (h) is one of the master batches of the examples, but the average particle size of OBSH is as small as 4 μm, so that foaming defects occur.

Comparative Example 4 is an example in which the masterbatch (g) is 10 parts by weight with respect to 100 parts by weight of LDPE. Comparative Example 4 has poor foaming, a density of 210 kg / m ³ , a foaming magnification of 4.8 times, and a comprehensive evaluation of “x”. Ammonia concentration and glass haze were not measured due to poor foaming. The master batch (g) is one of the master batches of the examples, but the average particle size of OBSH is as small as 4 μm, so that foaming defects occur.

Comparative Example 5 is an example in which the masterbatch (i) is 10 parts by weight with respect to 100 parts by weight of LDPE. In Comparative Example 5, since the masterbatch (i) in which the foaming agent was ADCA was used, the ammonia concentration was 900 ppm, the glass haze was 22%, and the overall evaluation was “x”.

As described above, in the present invention, a polyolefin-based crosslinked foam having a low residual ammonia concentration and capable of preventing contamination and corrosion by ammonia can be obtained.

The first aspect is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more and / or an ethylene-propylene-diene ternary copolymer having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40. A master batch for a polyolefin-based crosslinked foam containing baking soda and p, p'-oxybisbenzenesulfonyl hydrazide as a foaming agent.

The second aspect is characterized in that, in the first aspect , the foaming agent has a larger amount of p, p'-oxybisbenzenesulfonyl hydrazide than the amount of baking soda.

A third aspect is characterized in that, in the second aspect , the foaming agent is p, p'-oxybisbenzenesulfonyl hydrazide amount / baking soda amount = 5.5 / 4.5 to 77/23. And.

A fourth aspect is characterized in that, in any one of the first to third aspects, the particle size of the foaming agent is 8 to 30 μm.

A fifth aspect is a polyolefin-based crosslinked foam obtained from a kneaded product containing the polyolefin-based crosslinked foam masterbatch according to any one of the first to fourth aspects , a polyolefin-based resin, and a cross-linking agent. It is a polyolefin-based crosslinked foam having a density of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less.

The sixth aspect is characterized in that, in the fifth aspect , the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.

A seventh aspect is any one of claims 1 to 4 in a method for producing a polyolefin-based crosslinked foam having a density of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less. The masterbatch for a polyolefin-based crosslinked foam according to the above item, and a kneaded product containing a polyolefin-based resin and a cross-linking agent are foamed at a foaming ratio of 6 to 50 times by one-step foaming or two-step foaming.

The eighth aspect is characterized in that, in the seventh aspect , the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.

Claims (8)

Ethylene-vinyl acetate copolymer having a vinyl acetate content of 18% by weight or more and / or an ethylene-propylene-diene ternary copolymer having a Mooney viscosity (ML1 + 4, 100 ° C.) of 20 to 40, and baking soda and p as foaming agents. , P'-Master batch for polyolefin-based crosslinked foams containing oxybisbenzenesulfonyl hydrazide. The masterbatch for a polyolefin-based crosslinked foam according to claim 1, wherein the foaming agent has a larger amount of p, p'-oxybisbenzenesulfonyl hydrazide than the amount of baking soda. The polyolefin-based crosslinked foaming agent according to claim 2, wherein the foaming agent has an amount of p, p'-oxybisbenzenesulfonyl hydrazide / amount of baking soda = 5.5 / 4.5 to 77/23. Masterbatch for the body. The masterbatch for a polyolefin-based crosslinked foam according to any one of claims 1 to 3, wherein the foaming agent has a particle size of 8 to 30 μm. A polyolefin-based crosslinked foam obtained from a masterbatch for a polyolefin-based crosslinked foam according to any one of claims 1 to 4 and a kneaded product containing a polyolefin-based resin and a cross-linking agent, wherein the density is high. A polyolefin-based crosslinked foam having a concentration of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less. The polyolefin-based crosslinked foam according to claim 5, wherein the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin. The polyolefin-based according to any one of claims 1 to 4 in a method for producing a polyolefin-based crosslinked foam having a density of 20 to 160 kg / m ³ , an ammonia concentration of 0 ppm to 100 ppm, and a glass haze of 5% or less. A method for producing a polyolefin-based crosslinked foam, which comprises foaming a masterbatch for a crosslinked foam, a kneaded product containing a polyolefin resin, and a crosslinking agent at a foaming ratio of 6 to 50 times by one-step foaming or two-step foaming. .. The method for producing a polyolefin-based crosslinked foam according to claim 7, wherein the masterbatch for the polyolefin-based crosslinked foam is 7 to 80 parts by weight with respect to 100 parts by weight of the polyolefin-based resin.

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