JP3474178B2 - Vibration damping crosslinked resin foam and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vibration-damping crosslinked resin foam and a method for producing the same, and more specifically to a vibration-damping crosslinkable resin composition capable of foaming in an appropriate crosslinked state by controlling the crosslinking rate. TECHNICAL FIELD The present invention relates to a resin foam and a manufacturing method thereof.

[0002]

2. Description of the Related Art A vibration-damping crosslinked resin foam is soft and has a large vibration damping ability, so that sports shoes such as athletic shoes and pads, floor materials, etc. can be used for the purpose of absorbing shock and vibration.
Used for daily necessities. The vibration damping property of resin foams utilizes the phenomenon that the resin exhibits viscoelastic behavior near the glass transition temperature and near the second-order transition temperature below that temperature, internal friction increases, and vibration damping capacity increases. Is.

Conventionally, a damping material made of polyurethane foam has been used. For example, when a flexible polyurethane foam is produced, a specific amount of a foam stabilizer is used, and the ceiling and floor have both damping and sound absorbing properties. A vibration damping material (Japanese Patent Publication No. 5-8209), a soundproofing / damping material obtained by foaming an organic polyisocyanate and a specific polyol in the presence of a foaming agent, a catalyst, a foam stabilizer, and a plasticizer. A swing form (Japanese Patent Publication No. 7-25863) has been proposed.
The damping material made of these urethane foams is excellent in damping property, but has a drawback that it is inferior in weather resistance and water resistance.

A rubber-based vibration-damping foam having improved weather resistance and water resistance has also been proposed. For example, a method for producing a 1,2-polybutadiene foam excellent in vibration damping performance, having a low restoration speed, excellent shock absorption, and good compatibility with a thermoplastic resin (JP-A-7-62130), vibration damping, Of a vibration-damping resin foam obtained by cross-linking and foaming a molded product of a mixture of a 1,2-polybutadiene having a property of vibration and a vinyl bond-polyisoprene-polystyrene block copolymer having a vibration-damping property (JP-A-8- No. 208869) has been proposed. However, in the above-mentioned 1,2-polybutadiene foam of the prior art, since 1,2-polybutadiene has a vinyl group in the side chain, cross-linking easily occurs between side chains or between side chains and the main chain. As a result, it is hardened rapidly and lacks in elongation and flexibility.

As a means for solving this problem, Japanese Unexamined Patent Publication No.
No. 1-349717 discloses polystyrene and vinyl-
Polyisoprene-bonded triblock copolymer 70-
A method has been proposed in which a mixture of 95 parts by mass and 30 to 5 parts by mass of a polyethylene resin is crosslinked and foamed with an organic peroxide and a thermal decomposition type foaming agent.

[0006]

However, even in this method, since a double bond is present in the side chain of the vinyl-polyisoprene moiety, cross-linking is likely to occur, and the cross-linking reaction rapidly progresses, resulting in The binding of becomes sharply stronger.
As a result, it becomes hard and foaming becomes difficult, and cracking may occur due to excessive foaming in this state. Therefore, it is difficult to obtain a foam by balancing the crosslinking reaction and the foaming reaction, and it is also difficult to obtain a foam in the same foaming state.

Therefore, it is important to carry out foaming in an appropriate crosslinked state, but as described above, since crosslinking proceeds rapidly, crosslinking foaming is completed in an extremely short time, or an extremely small amount of a crosslinking agent is used for a long time. It must be crosslinked by applying. However, even if it is desired to carry out cross-linking and foaming in a short time, it takes 20 to 40 minutes to decompose the foaming agent, and particularly in the case of thick material molding, it takes a long time to mold, so this time is appropriate. In order to attain such a cross-linked state, the addition amount of the cross-linking agent must be 0.05 part or less with respect to 100 parts by mass of the resin. Since it is difficult to uniformly disperse the crosslinking agent in an amount of 0.05 part by mass with respect to 100 parts by mass of the resin, and the influence of a measurement error increases, it is not preferable.

The present invention solves the above problems and controls the balance between the cross-linking reaction and the foaming reaction by using a specific amount ratio of an antioxidant and a cross-linking agent, and suppresses vibrations by foaming in an appropriate cross-linked state. PROBLEM TO BE SOLVED: To provide a crosslinked resin foam and a method for producing the same.

[0009]

[Means for Solving the Problems] Generally, when a resin is cross-linked with an organic peroxide, the organic peroxide is decomposed by heat and becomes a free radical, and this free radical abstracts hydrogen of the molecule, and the molecule becomes a radical. Becomes Since this radical is in an unstable state as a molecule, the molecules recombine with each other to stabilize and form a crosslinked structure. At this time, as for the ease with which the hydrogen of the molecule is abstracted, the hydrogen bonded to the carbon of the double bond is most easily abstracted, and as a result, the rate of cross-linking is increased, causing the above problems. On the other hand, the antioxidant has an effect of trapping oxygen radicals generated when the resin is oxidatively deteriorated before the molecules are radicalized and stabilizing the resin.

When cross-linking with an organic peroxide, the organic peroxide is decomposed into free radicals. These free radicals abstract hydrogen in the molecule and, if an antioxidant is present, the above-mentioned reaction occurs. Since it is captured by the antioxidant, the crosslinking reaction is suppressed and the crosslinking rate is reduced. The present invention has been made based on such findings.

The vibration-damping crosslinked resin foam of the present invention has a vinyl bond with an aromatic vinyl block, which is a resin having a vibration-damping property.
A foam obtained by foaming and curing a resin composition containing a block copolymer comprising a diene block having a compound, a foaming agent, an antioxidant and an organic peroxide, The expansion ratio is 10 times or more, and the resin component is 1
The amount of the antioxidant is 0.5 to 1 when the amount is 100 parts by mass.
5 parts by mass, the organic peroxide is 0.1 to 0.7 parts by mass, and the mass ratio of the antioxidant to the organic peroxide is 1: (0.04 to 0.12). It is characterized by being.

The above-mentioned "resin having vibration damping property" is preferably a block copolymer having an aromatic vinyl block and a vinyl bond-diene block. In addition, poliure
Tan, polyimide, phenol and melamine
Be done . Aromatic vinyl monomers that compose this aromatic vinyl block include styrene, 2-methylstyrene, and 3
-Methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene and t
Examples include ert-butoxystyrene and the like. Examples of the diene-based monomer forming the vinyl bond-diene block include isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene and chloroprene having a vinyl bond. Among them, a block copolymer having a styrene block and a vinyl-isoprene block (for example, manufactured by Kuraray Co., Ltd., trade name “HYBRA 51
27 ") is preferably used. These block copolymers may be used alone or in combination of two or more.

The vinyl bond content of the diene block is preferably 30% or more, more preferably 40% or more.
In this case, the glass transition temperature of the resin is adjusted from 0 ° C. to around room temperature, and a vibration-damping crosslinked resin foam having excellent vibration-damping properties in a practical temperature range can be obtained.

The resin having the vibration damping property is 50 parts by mass or more (more preferably 60 to 95 parts by mass, further preferably 70 to 90 parts) when the resin component is 100 parts by mass.
(Parts by mass) is preferably contained. This content is 50
If it is less than the mass part, sufficient vibration damping properties may not be obtained.

As the resin component used in the present invention, in addition to the resin having the vibration damping property, "other resin" may be blended in order to improve the kneading processability. As other resins, for example, high-pressure method, polyethylene produced by a medium-pressure method or a low-pressure method, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene and methyl, ethyl, Copolymers of propyl or butyl with each acrylic acid ester (content of this ester; 45 mol% or less), or chlorinated compounds thereof each having a chlorine content of up to 60% by mass,
Further, a mixture of two or more kinds of these, or a mixture of these with isotactic polypropylene or atactic polypropylene can be exemplified. Other resins are preferably 50 parts by mass or less (more preferably 5 to 40 parts by mass, further preferably 10 to 30 parts by mass) when the resin component is 100 parts by mass. If this addition amount exceeds 50 parts by mass, the vibration damping property of the foam may be poor.

As the above-mentioned "antioxidant", 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2 , 2'-methylenebis (4-methyl-6-tert-butylphenol),
4,4 'thiobis (3-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-)
Hydroxy-5-tert-butylphenyl) butane,
Tetrakis- [methylene-3- (3 ', 5'-di-te
rt-Butyl-4′-hydroxyphenyl) propionate] methane (trade name “Irganox 1010”, manufactured by Ciba Specialty Chemicals) and the like. These may be used alone or in combination of two or more.

The amount of these antioxidants added is 0.5 to 15 parts by mass (preferably 1.0 to 10 parts by mass, more preferably 3 to 8 parts by mass) per 100 parts by mass of the resin component. . When the amount of the antioxidant added is less than 0.5 parts by mass,
The effect of suppressing the crosslinking rate cannot be sufficiently obtained. On the other hand, 1
When it exceeds 5 parts by mass, the effect of inhibiting crosslinking becomes too large, and the foam cannot be sufficiently crosslinked even if a large amount of organic peroxide is used.

Examples of the above-mentioned "organic peroxide" include dicumyl peroxide (for example, manufactured by NOF CORPORATION, trade name "Parkmill D"), 2,5-dimethyl-2,5-bis-tert-butylperoxide. Oxyhexane, 1,3-bis-tert-butylperoxy-isopropylbenzene, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane (for example, manufactured by NOF CORPORATION, trade name "Perhexa" 25B "), n-butyl-4,4-bis-tert-butylperoxyvalerate (for example,
Nippon Oil & Fats Co., Ltd. make and a brand name "Perhexa V") etc. are mentioned. These may be used alone or in combination of two or more.

The amount of these organic peroxides added is 0.1 to 0.7 parts by mass (preferably 0.2 to 0.6 parts by mass, more preferably 0.2 parts by mass) with respect to 100 parts by mass of the resin component. ~
0.5 parts by mass). The amount of organic peroxide added is 0.1
When the amount is less than the mass part, it is difficult to disperse the particles uniformly, and a measurement error is apt to occur, resulting in dispersion of the composition. On the other hand, when the amount exceeds 0.7 parts by mass, the crosslinking rate cannot be suppressed and the crosslinking proceeds rapidly, so that the foam tends to be cracked.

Further, the mass ratio of the antioxidant to the organic peroxide is 1: (0.04 to 0.12) [preferably 1:
(0.04-0.10), more preferably 1: (0.0
4 to 0.08)]. When this mass ratio is less than 0.04, the effect of inhibiting crosslinking becomes too large, and the foam cannot be sufficiently crosslinked. On the other hand, when it exceeds 0.12, the crosslinking reaction rapidly progresses, the balance between the crosslinking reaction and the foaming reaction becomes poor, and cracks and the like are likely to occur in the foam.

The above-mentioned "foaming agent" may be any as long as it has a decomposition temperature above the flow initiation temperature of the resin, such as azodicarbonamide, dinitrosopentamethylenetetramine, barium azodicarboxylate, trinitrotrimethyltriamine, and quench. Examples thereof include sodium acidate and sodium hydrogen carbonate. These may be used alone or in combination of two or more.

The amount of the foaming agent added is preferably 1 to 30 parts by mass (more preferably 2 to 10 parts by mass) per 100 parts by mass of the resin component. If this is less than 1 part by mass, the foaming may not proceed sufficiently and the desired foam may not be obtained. On the other hand, when the amount exceeds 30 parts by mass, the foaming proceeds so much that it is difficult to obtain a proper foamed state, and the desired foam may not be obtained.

The vibration-damping crosslinked resin foam of the present invention is
Excellent balance between cross-linking reaction and foaming reaction regardless of the foaming ratio and shape of the foam. Therefore, a foam having a high expansion ratio of 10 times or more (usually 40 times or less) can be obtained. Further, the vibration damping crosslinker of the present invention
The resin foam can be a thick foam having a thickness of 50 mm or more. The expansion ratio here is based on the volume.

The method for producing a vibration-damping crosslinked resin foam according to the present invention is an aromatic vinyl block which is a resin having a vibration-damping property.
And a diene block having a vinyl bond.
A method for producing a foam comprising a resin composition containing a copolymer, a foaming agent, an antioxidant and an organic peroxide, wherein the resin component is 100 parts by mass, The amount of the antioxidant added is 0.5 to 15 parts by mass,
The addition amount of the organic peroxide is 0.1 to 0.7 parts by mass, and the mass ratio of the antioxidant and the organic peroxide is 1: (0.04 to 0.12), It is characterized in that foaming is cured so that the expansion ratio is 10 times or more while balancing the crosslinking reaction and the foaming reaction. As the above-mentioned "resin having vibration damping property", "foaming agent", "antioxidant" and "organic peroxide", the above-mentioned ones can be used.

The above-mentioned antioxidant is added in an amount of resin component 10
0.5 to 15 parts by weight (preferably 1.
0 to 10 parts by mass, more preferably 3 to 8 parts by mass), and the addition amount of the organic peroxide is 100 parts by weight of the resin component.
0.1 to 0.7 parts by mass (preferably 0.
2 to 0.6 parts by mass, more preferably 0.2 to 0.5 parts by mass). Furthermore, the mass ratio of the antioxidant to the organic peroxide is 1: (0.04-0.12) [preferably 1:
(0.04-0.10), more preferably 1: (0.0
4 to 0.08)].

In this way, the cross-linking reaction and the foaming reaction are balanced by adjusting the addition amount of the antioxidant and the organic peroxide to a specific amount and the specific weight ratio of the antioxidant and the organic peroxide. It is possible to carry out foaming and curing.
That is, since the foaming can be performed while balancing the crosslinking reaction and the foaming reaction, the crosslinking does not proceed rapidly, the foam is not cracked, and the crosslinking is not insufficient. Therefore, in a normal temperature range and time, it is possible to foam in an appropriate cross-linked state, and it is possible to obtain a foam having substantially the same foamed state. Further, since it is not necessary to make the cross-linking agent extremely small, it is possible to disperse the cross-linking agent uniformly in the resin, and the influence of measurement error is reduced. Further, even when a usual amount of the cross-linking agent is added, the cross-linking reaction can be adjusted slowly, so that foaming can be easily performed and cracks and the like can be reduced.

In the above manufacturing method, a resin composition containing a resin having a vibration damping property, a foaming agent, a cross-linking agent, an antioxidant, an organic peroxide and other components is filled in a mold and pressurized, A method in which the crosslinking agent and the foaming agent are completely decomposed in a heated state, and then the resin composition is foamed to a desired density at one time by depressurizing (one-step foaming), and the resin composition is filled in a primary mold. Any of the methods (two-stage foaming) may be used (first-stage expansion) by heating under pressure to perform primary expansion, and then heating the resulting intermediate foam at normal pressure to perform secondary expansion to obtain a final foam having a desired density. .

It should be noted that the mold and other manufacturing equipment used may be those conventionally used in the manufacture of resin foams, and the pressure, temperature, etc., may be the type of resin, foaming agent, organic peroxide, etc. Can be set appropriately. Further, in order to control the foaming state of the foam, a compound containing urea as a main component, zinc oxide, metal oxides such as lead oxide, hexanoic acid,
Foaming aids such as lower or higher fatty acids such as stearic acid or their metal salts can be added. Further, for the purpose of improving physical properties, carbon black, zinc white, titanium oxide, and other additives usually used by being blended with the raw material of the main foam, for example, colorants, ultraviolet absorbers, flame retardants, crosslinking aids. Agents and the like can also be used.

Further, when the vibration-damping crosslinked resin foam is produced, it is preferable that the foaming and curing be carried out under pressure and airtightness. As a result, it is possible to manufacture a thick foam body in which oxidative deterioration due to oxygen and bubble roughening are suppressed. On the other hand, foaming under non-sealed conditions at atmospheric pressure may cause oxidative deterioration and bubble roughening.

Further, it was difficult to foam while maintaining a balance between the crosslinking reaction and the foaming reaction.
Double or more foam can be easily obtained. Further, even in the case of a thick plate-like foam having a thickness of 50 mm or more, it is possible to obtain a foam of excellent quality while balancing the crosslinking reaction and the foaming reaction.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to Examples and Comparative Examples. (1) Preparation of vibration-damping crosslinked resin foam (Examples 1 and 2 and Comparative Examples 1 and 2)
A mixture prepared by blending the components shown below in the proportions shown in Table 1,
After kneading with a kneader at a temperature of 100 ° C. for 20 minutes and then with a biaxial mixing roll at a temperature of 100 ° C. for 10 minutes to prepare a resin composition, the resin composition was filled into a mold heated to 150 ° C. and 10 MPa. The foaming was performed for 40 minutes under the pressure of 1 to obtain a vibration-damping crosslinked resin foam of 1 m × 2 m × 50 mm. The expansion ratios of Examples 1 and 2 and Comparative Examples 1 and 2 were all 10 times.

Details of the components used in Examples and Comparative Examples are shown below. (A) A resin having vibration damping property; a block copolymer having a styrene block and a vinyl bond-isoprene block, manufactured by Kuraray Co., Ltd., under the trade name of "HIBLER 5127" (the ratio of vinyl bond is 40% or more) (b) Other resins: polyethylene, manufactured by Tosoh Corporation, trade name "Petrosene 170" (c) Foaming agent: azodicarbonamide, manufactured by Eiwa Chemical Co., Ltd.,
Product name "AC # 3" (d) Foaming aid; Second class zinc white; Zinc stearate (e) Urea-based foaming aid; Eiwa Chemical Co., Ltd., trade name "Cellpaste 101" (f) Organic peroxide Thing; dicumyl peroxide (g) antioxidant; Ciba Specialty Chemicals make, brand name "Irganox 1010"

[0033]

[Table 1]

(2) Evaluation of performance of vibration-damping crosslinked resin foam The foaming state of each vibration-damping crosslinked resin foam obtained in (1) above was visually evaluated. The results are shown in Table 2.

[0035]

[Table 2]

According to Table 2, in Comparative Examples 1 and 2 in which the antioxidant is not contained, foaming gas is generated when the crosslinking speed is too fast and the vibration-damping crosslinked resin foam is hard and difficult to extend. So it cracked or shattered. On the other hand, in Examples 1 and 2 containing the antioxidant, the crosslinking rate was suppressed, the crosslinking proceeded at an appropriate rate, the crosslinking rate and the foaming reaction were well balanced, and there was no crack or the like. It was a vibration-damping crosslinked resin foam having an external appearance. The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention depending on the purpose and application.

[0037]

INDUSTRIAL APPLICABILITY The resin composition for producing the vibration-damping crosslinked resin foam of the present invention has a good balance between the crosslinking reaction and the foaming reaction and has a high expansion ratio or a thick material. It is possible to obtain a foam having an excellent appearance without cracks and the like. Furthermore, according to the method for producing a vibration-damping crosslinked resin foam of the present invention, the antioxidant and the organic peroxide each have a specific addition amount, and the antioxidant and the organic peroxide have a specific mass ratio. Since the resin composition is foam-cured while balancing the crosslinking reaction and the foaming reaction, it becomes possible to easily foam in a moderately crosslinked state by controlling the crosslinking rate, and a stable vibration-damping crosslinked resin foam is obtained. Can be manufactured.

Continuation of front page (51) Int.Cl. ⁷ identification code FI // (C08K 5/04 C08K 5:13 5:13 5:14 5:14) (58) Fields investigated (Int.Cl. ⁷ , DB Name) C08J 9/00-9/42 C08K 3/00-13/08 C08L 1/00-101/16

Claims (4)

(57) [Claims] 1. A vinyl bond with an aromatic vinyl block
A foam obtained by foaming and curing a resin composition containing a block copolymer having a diene block , a foaming agent, an antioxidant, and an organic peroxide, and having a foaming ratio of 10 times or more. And the above resin component is 10
When the amount is 0 part by mass, the amount of the antioxidant is 0.5 to 15
Parts by mass, the organic peroxide is 0.1 to 0.7 parts by mass, and the mass ratio of the antioxidant and the organic peroxide is 1: (0.04 to 0.12). A vibration-damping crosslinked resin foam characterized by the above. 2. The above resin further comprises ethylene-propylene.
Copolymer, ethylene-butene copolymer, ethylene-acetic acid
Vinyl copolymer, ethylene and methyl, ethyl, propylene
Copolymerization of acrylic acid or butyl with each acrylic ester
Body (content of acrylic acid ester is within 45 mol%),
Or chlorine containing up to 60% by mass of chlorine
Compound, a mixture of two or more of these, or
Isotactic polypropylene or atactic polypropylene
The vibration-damping crosslinked resin foam according to claim 1 , which contains a mixture with polypropylene . 3. The vibration-damping crosslinked resin foam according to claim 2, wherein the vinyl bond content of the diene block is 30% or more. 4. An aromatic vinyl block and a vinyl bond
A block copolymer having a diene block having
Resin component, foaming agent, antioxidant and organic peroxide.
A method for producing a foam comprising a resin composition having,
When the above resin component is 100 parts by mass, the above antioxidant
The amount of the stopper added is 0.5 to 15 parts by mass, and the above organic peroxide is used.
Is 0.1 to 0.7 parts by mass, and the antioxidant
The mass ratio of the stopper and the organic peroxide is 1: (0.04 to
0.12) while balancing the crosslinking reaction and the foaming reaction
Foam and cure so that the expansion ratio is 10 times or more.
A method for producing a vibration-damping crosslinked resin foam, comprising: