JP2002317067A - Vibration-dumping crosslinked resin foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-dumping resin foam capable of being foamed in a proper crosslinked state caused by the control of a crosslinked rate, and further to provide a method for producing the foam. SOLUTION: The foam obtained by foaming and hardening a composition comprising a resin component including a resin having the vibration-dumping properties (a block copolymer having a styrene block and a vinyl bond-isoprene block, or the like), a foaming agent, an antioxidant and an organic peroxide is regulated so that the amounts of the antioxidant and the organic peroxide may be 0.5-15 pts.wt. (especially 3-8 pts.wt.) and 0.1-0.7 pts.wt. (especially 0.2-0.5 pts.wt.), respectively, based on 100 pts.wt. resin component, and the weight ratio of the antioxidant to the organic peroxide may be 1:(0.04-0.12) [especially 1:(0.04-0.08)].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-damping crosslinked resin foam and a method for producing the same, and more particularly, to a vibration-damping crosslinked resin capable of foaming in an appropriate crosslinked state by controlling a crosslinking speed. The present invention relates to a resin foam and a method for producing the same.

[0002]

2. Description of the Related Art A vibration-damping crosslinked resin foam is soft and has a large vibration damping ability, and is used for sports shoes such as athletic shoes and pads, flooring materials, etc. for the purpose of shock absorption and vibration absorption.
Used in daily necessities. The vibration damping properties of resin foams are based on the phenomenon that the resin exhibits viscoelastic behavior near the glass transition temperature or near the secondary transition temperature below that temperature, increasing internal friction and increasing vibration damping capacity. It is.

Conventionally, a vibration damping material made of polyurethane foam has been used. For example, when a flexible polyurethane foam is manufactured, a specific amount of a foam stabilizer is used, and a ceiling or floor having both vibration damping performance and sound absorbing performance is used. (Japanese Patent Publication No. 5-8209), a soundproofing / damping 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 shake form (Japanese Patent Publication No. 7-25863) has been proposed.
The vibration damping materials made of these urethane foams have excellent vibration damping properties, but have a disadvantage in that they are 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 having excellent vibration damping performance, a low restoration speed, excellent shock absorption, and good compatibility with a thermoplastic resin (Japanese Patent Application Laid-Open No. 7-62130), Damping resin foam obtained by crosslinking and foaming a molded article of a mixture of 1,2-polybutadiene having a viscosity and a vinyl bond-polyisoprene-polystyrene block copolymer having a damping property (Japanese Patent Application Laid-Open No. 8- No. 208869) has been proposed. However, in the prior art 1,2-polybutadiene foam, since 1,2-polybutadiene has a vinyl group in a side chain, it is likely to be crosslinked by bonding between side chains or between a side chain and a main chain. Is disadvantageous in that it hardens rapidly, resulting in insufficient elongation and flexibility.

As means for solving this problem, Japanese Patent Laid-Open No.
No. 1-349717 discloses polystyrene and vinyl-.
Triblock copolymer 70 to which polyisoprene is bonded
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 cross-linked and foamed with an organic peroxide and a pyrolytic foaming agent.

[0006]

However, even in this method, since a double bond is present in the side chain of the vinyl-polyisoprene portion, crosslinking is likely to occur, and the crosslinking reaction proceeds rapidly, and the Rapidly increases.
As a result, it becomes hard and foaming becomes difficult, and in this state, foaming may be forcibly caused to cause cracks. 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 having the same foaming state.

Therefore, it is important to foam in an appropriate cross-linked state. However, as described above, since the cross-linking proceeds rapidly, the cross-linking and foaming can be completed in a very short time, or a very small amount of a cross-linking agent can be used for a short time. To crosslink. However, even if it is desired to carry out crosslinking and foaming in a short time, it takes 20 to 40 minutes to decompose the foaming agent. If an attempt is made to make the crosslinked state satisfactory, the amount of the crosslinking agent added must be 0.05 parts or less per 100 parts by mass of the resin. It is difficult to uniformly disperse the resin with 0.05 part by mass of the crosslinking agent with respect to 100 parts by mass of the resin, and the influence of the measurement error increases, which is not preferable.

The present invention solves the above-mentioned problems, and controls the balance between a crosslinking reaction and a foaming reaction by using a specific quantitative ratio of an antioxidant and a crosslinking agent, thereby suppressing vibrations in an appropriate crosslinked state. It is an object to provide a crosslinked resin foam and a method for producing the same.

[0009]

Generally, when a resin is crosslinked with an organic peroxide, the organic peroxide is decomposed by heat to form free radicals, and the free radicals extract hydrogen of the molecules, and the molecules are converted into radicals. Becomes Since these radicals are in an unstable state as molecules, the molecules are recombined with each other for stabilization to form a crosslinked structure. At this time, hydrogen bonded to the carbon of the double bond is most easily extracted as hydrogen of the molecule, and as a result, the speed of crosslinking increases, and the above-described problem occurs. On the other hand, the antioxidant has an effect of capturing oxygen radicals generated when the resin is oxidized and degraded before the molecules are radicalized, thereby stabilizing the resin.

When crosslinking is carried out with an organic peroxide, the organic peroxide is decomposed to form free radicals. The free radicals extract hydrogen in the molecule and, when an antioxidant is present, as described above. Since the antioxidant is trapped by the antioxidant, the crosslinking reaction is suppressed, and the crosslinking speed is reduced. The present invention has been made based on such findings.

The vibration-damping crosslinked resin foam according to claim 1 is
A foam obtained by foaming and curing a resin composition containing a resin having a damping property, a foaming agent, an antioxidant and an organic peroxide, wherein the resin component is 100 parts by mass. In addition, 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 to the organic peroxide is 1: (0.
04 to 0.12).

The "resin having a vibration damping property" is not particularly limited as long as it is a resin forming a foam, and examples thereof include polyurethane, polyimide, phenol and melamine. In order to obtain a damping resin foam having excellent damping properties, a block copolymer having an aromatic vinyl block and a vinyl bond-diene block is particularly preferable. As the aromatic vinyl monomer constituting the aromatic vinyl block, styrene, 2-
Methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-
Butylstyrene and tert-butoxystyrene. The diene monomers constituting the vinyl bond-diene block include isoprene, 1,3-butadiene, and 2,3-dimethyl-1,3 having a vinyl bond.
-Butadiene and chloroprene. Among them, a block copolymer having a styrene block and a vinyl-isoprene block (for example, trade name “Hibler 5127” manufactured by Kuraray Co., Ltd.) is preferably used.
These block copolymers may be used alone or 2
Mixtures of more than one species can be used.

Further, as described in claim 3, the diene block preferably has a vinyl bond content of 30% or more, particularly 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 damping crosslinked resin foam having excellent damping properties in a practical temperature range can be obtained.

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

As the resin component used in the present invention, "other resins" may be added in addition to the resin having the above-mentioned vibration damping properties to improve the kneading processability. As other resins, for example, a high-pressure method, polyethylene produced by a medium-pressure method or a low-pressure method, an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-vinyl acetate copolymer, ethylene and methyl, ethyl, A copolymer of propyl or butyl with each acrylate (the content of this ester; within 45 mol%), or a chlorinated product thereof having a chlorine content of up to 60% by mass;
Further, a mixture of two or more of these, a mixture of these with isotactic polypropylene or atactic polypropylene, and the like can be given. The other resin is preferably 50 parts by mass or less (more preferably 5 to 40 parts by mass, and still more preferably 10 to 30 parts by mass) when the resin component is 100 parts by mass. If the amount exceeds 50 parts by mass, the foam may have poor vibration damping properties.

The above "antioxidants" include 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, , 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 as a mixture of two or more.

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

Examples of the "organic peroxide" include dicumyl peroxide (for example, trade name "Parkmill D" manufactured by NOF Corporation), 2,5-dimethyl-2,5-bis-tert-butyl peroxide. Oxyhexane, 1,3-bis-tert-butylperoxy-isopropylbenzene, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane (for example, trade name "Perhexa" manufactured by NOF Corporation) 25B "), n-butyl-4,4-bis-tert-butylperoxyvalerate (e.g.,
Nippon Yushi Co., Ltd., trade name "Perhexa V") and the like. These may be used alone or as a mixture of two or more.

The amount of these organic peroxides to be added is 0.1 to 0.7 parts by mass (preferably 0.2 to 0.6 parts by mass, more preferably 0.2 to 0.7 parts by mass) per 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 parts by mass, it is difficult to uniformly disperse the components, and a measurement error is apt to occur. On the other hand, if the amount exceeds 0.7 parts by mass, the crosslinking speed cannot be suppressed and the crosslinking proceeds rapidly, and cracks and the like easily occur in the foam.

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 crosslinking inhibition effect becomes too large, and the foam cannot be sufficiently crosslinked. On the other hand, when it exceeds 0.12, the cross-linking reaction rapidly proceeds, the balance between the cross-linking reaction and the foaming reaction is deteriorated, and the foam is easily cracked.

The "foaming agent" may be any one having a decomposition temperature equal to or higher than the flow start temperature of the resin. And sodium bicarbonate. These may be used alone or as a mixture of two or more.

The amount of the foaming agent is preferably 1 to 30 parts by mass (more preferably 2 to 10 parts by mass) based on 100 parts by mass of the resin component. If the amount is less than 1 part by mass, foaming does not proceed sufficiently, and a desired foam may not be obtained. On the other hand, when the amount exceeds 30 parts by mass, foaming proceeds too much to obtain an appropriate foamed state, and a desired foam may not be obtained.

Further, the vibration-damping crosslinked resin foam of the present invention comprises:
The balance between the crosslinking reaction and the foaming reaction is excellent irrespective of the expansion ratio, the shape, etc. of the foam. Therefore, claim 4
As described, the foaming ratio should be 10 times or more (usually 40 times or less) to be a high-magnification foam, or the thickness should be 50 m.
m or more. Here, the expansion ratio is based on the volume.

According to a fifth aspect of the present invention, there is provided a method for producing a damping crosslinked resin foam comprising a resin component containing a resin having a damping property, a foaming agent, an antioxidant, and a resin composition containing an organic peroxide. A method for producing a foam, comprising:
When the amount is 00 parts by mass, the addition amount of the antioxidant is 0.5 to 15 parts by mass, and the addition amount of the organic peroxide is 0.1 part by mass.
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 foaming and curing while balancing the crosslinking reaction and the foaming reaction. The above-mentioned "resin having vibration damping properties", "blowing agent", "antioxidant" and "organic peroxide" can be used.

The amount of the antioxidant added depends on the amount of the resin component 10
0.5 to 15 parts by mass relative to 0 parts by mass (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 mass of the resin component.
0.1 to 0.7 parts by mass relative to parts by mass (preferably 0.1 to 0.7 parts by mass).
2 to 0.6 parts by mass, more preferably 0.2 to 0.5 parts by mass). 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)].

As described above, the crosslinking reaction and the foaming reaction are balanced by setting the specific amounts of the antioxidant and the organic peroxide and the specific mass ratio of the antioxidant and the organic peroxide. It is possible to foam and harden while performing.
That is, since the foaming can be carried out while maintaining the balance between the crosslinking reaction and the foaming reaction, the bridging does not proceed rapidly, and the foam is not cracked or the crosslinking is not insufficient. Therefore, the foam can be foamed in an appropriate cross-linked state within a normal temperature range and time, and a foam having almost the same foaming state can be obtained. Further, since it is not necessary to use an extremely small amount of the cross-linking agent, the cross-linking agent can be uniformly dispersed in the resin, and the influence of the measurement error is reduced. Furthermore, even when a usual amount of a crosslinking agent is added, the crosslinking reaction can be adjusted late, so that foaming can be easily performed and cracks and the like can be reduced.

In the above production method, a mold is filled with a resin composition containing a resin having a damping property, a foaming agent, a crosslinking agent, an antioxidant, an organic peroxide and other components, A method in which the cross-linking agent and the foaming agent are completely decomposed in a heated state, and thereafter, the resin composition is foamed to a desired density at a time by removing pressure (single-stage foaming), and the resin composition is filled in a primary mold. Heating under pressure to cause primary expansion, and then heating the obtained intermediate foam at normal pressure to cause secondary expansion to obtain a final foam having a desired density (two-stage foaming). .

As the mold and other manufacturing equipment, those conventionally used in the production of resin foams can be used, and the pressure, temperature, etc. are determined by the type of resin, foaming agent, organic peroxide, etc. Can be set as appropriate. Further, in order to control the foaming state of the foam, urea-based compound, zinc oxide, metal oxides such as lead oxide, hexanoic acid,
Foaming aids such as lower or higher fatty acids such as stearic acid or metal salts thereof can be added. Furthermore, for the purpose of improving the 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, a coloring agent, an ultraviolet absorber, a flame retardant, a crosslinking aid Agents and the like can also be used.

Further, when producing a vibration-damping crosslinked resin foam, it is preferable that foaming and curing be carried out under pressure and airtight. Thereby, it is possible to manufacture a thick foam in which oxidation deterioration and bubble roughness due to oxygen are suppressed. On the other hand, foaming under normal pressure and non-sealing may cause oxidative deterioration and bubble roughness.

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

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to Examples and Comparative Examples. (1) Preparation of damping crosslinked resin foam (Examples 1 and 2 and Comparative Examples 1 and 2) For a total of 100 parts by mass of the resin component,
A mixture of the components shown below in the proportions shown in Table 1,
The mixture was kneaded 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 form a resin composition. The mixture was filled into a mold heated to 150 ° C. Under pressure of 40 minutes to obtain a vibration-damping crosslinked resin foam of 1 mx 2 mx 50 mm. The expansion ratios of Examples 1 and 2 and Comparative Examples 1 and 2 were all 10 times.

The details of the components used in the examples and comparative examples are shown below. (A) a resin having a vibration damping property; a block copolymer having a styrene block and a vinyl bond-isoprene block, manufactured by Kuraray Co., Ltd., trade name “Hibler 5127” (the ratio of vinyl bonds is 40% or more) (b) Other resins: polyethylene, manufactured by Tosoh Corporation, trade name “Petrocene 170” (c) Blowing agent: azodicarbonamide, manufactured by Eiwa Chemical Co.,
Product name "AC # 3" (d) Foaming aid; second class zinc white; zinc stearate (e) Urea-based foaming aid; product name "Cell Paste 101" manufactured by Eiwa Chemical Co., Ltd. (f) Organic peroxidation Dicumyl peroxide (g) Antioxidant; trade name “Irganox 1010” manufactured by Ciba Specialty Chemicals

[0033]

[Table 1]

(2) Evaluation of Performance of Damping-Crosslinked Cross-Linked Resin Foam The foaming state of each of the vibration-damping cross-linked resin foams obtained in the above (1) was visually evaluated. Table 2 shows the results.

[0035]

[Table 2]

According to Table 2, in Comparative Examples 1 and 2 containing no antioxidant, a foaming gas is generated in a state where the crosslinking speed is too fast and the vibration-damping crosslinked resin foam is hard and hard to expand. As a result, it cracked or shattered. On the other hand, in Examples 1 and 2 in which the antioxidant is contained, the crosslinking speed is suppressed, the crosslinking proceeds at an appropriate speed, the balance between the crosslinking speed and the foaming reaction is good, and there is no crack. It was a vibration damping crosslinked resin foam having an appearance. It should be noted that the present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention in accordance with the purpose and application.

[0037]

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 and a thick foam. And a foam having an excellent appearance without cracks or 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 are each added in a specific amount, and the antioxidant and the organic peroxide are in a specific mass ratio. In order to foam and cure the resin composition while balancing the crosslinking reaction and the foaming reaction, it is possible to easily foam the resin composition in an appropriate crosslinked state by controlling the crosslinking speed, and to stably dampen the crosslinked resin foam. Can be manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16F 15/02 F16F 15/02 Q F term (Reference) 3J048 BA24 BA25 BB10 4F074 AA13B AA17 AA32B AA97 AD08 AG04 BA13 BA28 BB02 CA24 CC06Y DA02 DA40 4J002 AA001 BP011 CC031 CC181 CK021 CM041 DE206 EG056 EJ017 EJ027 EJ037 EJ047 EK008 EK038 EK058 EK068 EQ016 ES006 FD077 FD148 FD326 GC00 GL00

Claims (5)

[Claims] 1. A foam obtained by foaming and curing a resin component containing a resin having a damping property, a foaming agent, an antioxidant and an organic peroxide, wherein the resin component is 100%. When the amount is 0.5 parts by mass, the antioxidant is 0.5 parts by mass.
To 15 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). A vibration-damping crosslinked resin foam, characterized in that: 2. The vibration-damping crosslinked resin foam according to claim 1, wherein the vibration-damping resin is a block copolymer comprising an aromatic vinyl block and a diene block having a vinyl bond. 3. The vibration-damping crosslinked resin foam according to claim 2, wherein the vinyl bond amount of the diene block is 30% or more. 4. The vibration-damping crosslinked resin foam according to claim 1, which has an expansion ratio of 10 times or more. 5. A method for producing a foam comprising a resin component containing a resin having a damping property, a foaming agent, an antioxidant, and a resin composition containing an organic peroxide, wherein the resin component is 100 mass%. Parts, the added amount of the antioxidant is 0.5 to 15 parts by mass, and the added amount of the organic peroxide is 0.1 part by mass.
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),
A method for producing a vibration-damping crosslinked resin foam, wherein foaming and curing are performed while balancing a crosslinking reaction and a foaming reaction.