JPH0781061B2 - Acrylic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an acrylic elastomer composition. More specifically, it relates to an acrylic elastomer composition which is transparent, has a vibration damping effect, and can be colored in any color.

[Conventional technology]

Conventional rubber is colored black mainly because it uses a filler such as carbon black. Therefore, it is not possible to add a dye to color it in any color, and to add transparency to the rubber. Was also impossible.

That is, conventionally commercially available raw rubber is poor in transparency, and various fillers mainly containing carbon black, reinforcing agents, compounding chemicals, etc. are added in various types according to the purpose of use, so that the rubber can be colored in any desired color. It is almost impossible to color it, and since it has poor vibration proofing except for special cases, it cannot be used for various applications requiring vibration proofing. is doing.

[Problems to be solved by the invention]

The applicant has previously described (a) an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and / or 2 to 8 carbon atoms.
And (c) at least one of the following monomers (a) epoxy group-containing vinyl monomer (b) carboxyl group-containing vinyl monomer (c) reactive halogen-containing vinyl monomer Polymer (d) Diene-based monomer (e) Hydroxyl group-containing vinyl monomer (f) Amide group-containing vinyl monomer Acrylic elastomer composed of copolymer is found to be superior in light transmittance However, (JP-A-61-184507
Gazette), by adding powdered poly (lower alkyl methacrylate) or silica to such a light-transparent acrylic elastomer, it has been found that it is excellent in anti-vibration action and can be colored in any color while maintaining its transparency, We have succeeded in effectively solving the above problems found in rubber.

[Means for solving problems]

Therefore, the present invention relates to an acrylic elastomer composition,
This acrylic elastomer composition has (a) a carbon number of 1 to
An alkyl acrylate having 8 alkyl groups and /
Alternatively, (b) an alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms and (c) at least one of the following monomers (a) an epoxy group-containing vinyl monomer (b) a carboxyl group-containing vinyl monomer (C) Reactive halogen-containing vinyl monomer (D) Diene monomer (V) Hydroxyl group-containing vinyl monomer (F) Amide group-containing vinyl monomer Copolymer of light-transmitting acrylic elastomer and It contains powdery poly (lower alkyl methacrylate) or silica having a refractive index n _D of 1.45 to 1.50.

Examples of the alkyl acrylate of the component (a) forming the copolymer include methyl acrylate, ethyl acrylate, n- or iso-propyl acrylate, n- or iso-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2 -Alkyl acrylates having an alkyl group having 1 to 8 carbon atoms (including those having a substituent such as a cyano group) such as ethylhexyl acrylate, n-octyl acrylate, and 2-cyanoethyl acrylate are used, and preferably ethyl acrylate or n -Butyl acrylate is used.

Examples of the alkoxyalkyl acrylate as the component (b) include methoxymethyl acrylate, ethoxymethyl acrylate, 2-methoxyethyl acrylate, and 2
An alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms such as ethoxyethyl acrylate or 2-butoxyethyl acrylate is used,
2-methoxyethyl acrylate and 2-ethoxyethyl acrylate are preferably used.

These components (a) and / or (b) are about 9
It is used by being copolymerized at a ratio of 9.9 to 90 mol%, (a)
When both the component and the component (b) are used, the former is generally used in a proportion of about 10 to 90 mol% and the latter in a proportion of about 90 to 10 mol%.

A part of the component (a) and / or the component (b), specifically about 10 mol% may be substituted with another copolymerizable monomer and copolymerized. Examples of such copolymerizable monomers include vinyl chloride, vinylidene chloride, acrylonitrile, styrene, vinyl acetate, ethyl vinyl ether,
Butyl vinyl ether, alkyl methacrylate, alkoxyalkyl methacrylate and the like can be mentioned.

As the cross-linking agent used depending on the type of the component (c) forming the cross-linking point of the copolymer and the reactive group thereof, the following are used.

(A) Epoxy group-containing vinyl monomer allyl glycidyl ether, glycidyl acrylate,
Glycidyl methacrylate and the like are exemplified, as these cross-linking agents, for example, diamine triamine, polyamines such as metaphenylenediamine, polycarboxylic acids such as adipic acid, pyromellitic anhydride, acid anhydrides such as maleic anhydride, polyamides. , Sulfonamides and the like are used.

(B) carboxyl group-containing vinyl monomer acrylic acid, methacrylic acid, itaconic acid and the like are exemplified, as the cross-linking agent, for example, polyepoxides such as ethylene glycol glycidyl ether, 1,6-hexanediol diglycidyl ether, Polyols such as 1,4-butanediol and 1,1,1-trimethylolpropane are used. Instead of using these cross-linking agents, the cross-linking may be performed only by heating.

(C) Reactive halogen-containing monomer 2-chloroethyl vinyl ether, monochloroacetic acid and the like are exemplified, and examples of the cross-linking agent thereof include polyamines such as diethylenetriamine and triethylenetetramine, and polycarbamates such as hexamethylenediamine carbamate. Are used.

(D) Diene monomer Divinylbenzene, piperylene, isoprene, pentadiene, vinylcyclohexane, chloroprene, butadiene, methylbutadiene, cyclopentadiene, methylpentadiene, ethylene glycol diacrylate, propylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol Dimethacrylate and the like are exemplified, and as the cross-linking agent, for example, sulfur, or organic peroxides such as benzoyl peroxide and dicumyl peroxide, azo compounds such as azobisisobutyronitrile, divinylbenzene, and triary Lucyanurate and triallyl isocyanurate are used. Instead of using these cross-linking agents, the cross-linking may be performed only by heating.

(E) Hydroxyl group-containing vinyl monomer hydroxyalkyl acrylate, hydroxyalkyl methacrylate, hydroxyalkoxy acrylate,
Examples of N-methylol acrylamide include polyisocyanates such as hexamethylene diisocyanate and tolylene diisocyanate, polycarboxylic acids such as adipic acid, and alkoxymethylmelamines such as methoxymethylmelamine. To be

(F) Amide group-containing vinyl monomer: acrylamide, methacrylamide, etc. are exemplified, and as these curing agents, for example, aminoformaldehyde is used. Moreover, you may make it bridge | crosslink only by heating.

The copolymerization of the respective components of the above-mentioned copolymerizable monomer is preferably carried out by the bulk polymerization method or the solution polymerization method, and not preferably by the emulsion polymerization method. This is because, in the emulsion polymerization method, the residue of the water-soluble polymerization initiator, the emulsifier and the salting-out agent are mixed in the copolymer elastomer to significantly reduce the light transmittance. When the bulk polymerization method is used, it becomes difficult to control the reaction conditions when the polymerization yield is high, and gelation is likely to occur during the reaction, so that the polymerization rate should be within the range of about 20 to 70%. The reaction must be stopped. Then, after the reaction is completed, the unreacted material is separated to obtain a copolymer elastomer having good light transmittance.

The solution polymerization method is suitable as a method for producing a copolymer elastomer having a high yield and good light transmittance. In the solution polymerization method, as a solvent, for example, benzene, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone,
Ethyl acetate, butyl acetate, etc. are used.For each monomer component, a commercially available monomer is distilled off under reduced pressure after the polymerization inhibitor is removed by a conventional method, and as a polymerization initiator, a commercially available product is repeatedly used with pure ethanol. Azobisisobutyronitrile, benzoyl peroxide, etc. which are purified by recrystallization are used.

The copolymerization reaction is specifically carried out as follows, for example. A flask equipped with a reflux condenser, a dropping funnel, and a stirrer is charged with 100 parts by weight of the solvent (amount of about 5 to 98% by weight in the copolymer solution to be formed) and maintained at a predetermined temperature. Approximately 10 monomer mixture in the dropping funnel.
A solution prepared by dissolving about 1 to 10 parts by weight of the polymerization initiator in about 900 parts by weight is added dropwise over about 0.5 to 5 hours, and the reaction is continued for about 1 to 5 hours after completion of the addition. Under such reaction conditions, the polymerization rate is about 80 to 95%. In order to further increase the polymerization rate, about 1 to 5 parts by weight of a polymerization initiator is added after the dropping of the monomer mixture, whereby the polymerization rate can be 99% or more.

When such a dropping polymerization method is adopted, there is an advantage that a copolymer elastomer having a uniform composition can be obtained because the copolymerization ratios of the monomers having different reactivities are not significantly different between the start and the end of the polymerization. When copolymerizing monomers with extremely different reactivity, increase the concentration of the monomer with low reactivity in the initial stage of dropping and decrease the concentration in the latter stage of dropping to obtain a relatively uniform composition. A copolymer elastomer of is obtained.

The obtained copolymer elastomer has a refractive index n _D of 1.45 to
1.50 poly (lower alkyl) methacrylates such as polymethylmethacrylate, polyethylmethacrylate or silica powder (generally having a particle size of about 50 μm or less) is used in an amount of about 5 to 50 parts by weight, preferably 100 parts by weight of the copolymer elastomer. About 10-40 parts by weight is added. The reason why the refractive index as described above is used is to make the refractive index almost the same as that of the transparent acrylic elastomer, and as for the addition ratio, the addition of less than this gives the desired anti-vibration effect. On the other hand, if it is used in a larger amount than this, the light transmittance is remarkably lowered, and the rubber physical properties such as elongation and tensile strength are also lowered. As the copolymer elastomer, in addition to these powdery substances, dyes for coloring, for example, fat-soluble dyes such as Sudan Red, Spirit Blue, Indantron Helidone Yellow, and Sulfa Black T are used. About 0.1 to 10 parts by weight, preferably about 1 to 5 parts by weight, may be added per 100 parts by weight to give an arbitrary color.

In addition to the above components, the composition is prepared by using a crosslinking agent according to the type of component (c), such as hexamethylene diisocyanate or tolylene diisocyanate when a hydroxyl group-containing monomer is used. 0.1 to 10 parts by weight, preferably about 1 to 5 per 100 parts by weight of the copolymer elastomer.
After addition of parts by weight, necessary components are further added, followed by kneading with a roll mill or benzene, toluene, xylene,
After mixing and dispersing with a solvent such as methyl ethyl ketone or methyl isobutyl ketone, the solvent is volatilized.

The composition thus prepared adjusts the composition ratio of each monomer used in the production of the copolymer, the type and ratio of the powdered substance to be added, the degree of formation of a three-dimensional network structure by crosslinking, and the like. By doing so, the visible light transmittance of the cross-linked cured product of this composition can be set to 30% or more, and further vibration damping properties can be imparted.

The cross-linking of the composition is performed under the cross-linking conditions usually used for acrylic elastomers.

〔The invention's effect〕

The acrylic elastomer composition according to the present invention has a thickness of 10 mm.
The visible light transmittance is about 85% or more per light-transmissive acrylic elastomer, and by adding powdered poly (lower alkyl methacrylate) or silica having a refractive index almost equal to this to the visible light transmittance. From the practical point of view, it is possible to impart the vibration absorbing property to the acrylic elastomer and to color it to an arbitrary color while maintaining the transparency of the acrylic elastomer without substantially lowering it.

As a result, the acrylic elastomer composition utilizes these characteristics to make colored oil seals, O-rings, packings, boots or vibration damping films, vibration damping members for disc brake pad shims, precision instruments, and medical instruments. It can be effectively used for molding packaging materials such as and cover materials.

〔Example〕

 Next, the present invention will be described with reference to examples.

Example 1 96 mol% of purified ethyl acrylate and 2%
-Polyethylmethacrylate (average particle size: 5 μm, n _D ; 1.49) was added to 100 parts (weight, hereinafter the same) of a copolymer obtained by solution polymerization of 4 mol% of hydroxyethyl acrylate using azobisisobutyronitrile as a polymerization initiator. ) 20 parts, 0.5 parts of Sudan Red and 3 parts of tolylene diisocyanate were added and dissolved homogeneously in methyl ethyl ketone with stirring.

The methyl ethyl ketone solution was uniformly coated on one side of a cold-rolled steel sheet with a thickness of 0.5 mm, and after removing the solvent by drying, it was heated and pressed at 160 ° C for 40 minutes with a heat press to give a rubber thickness of 0.2 mm and a large size. A 50 × 100 mm laminated plate was produced.

Comparative Example 1 In Example 1, a laminated board was manufactured without using powdered polymethylmethacrylate.

Comparative Example 2 In Example 1, a laminate was manufactured by changing the amount of powdery polymethylmethacrylate to 80 parts.

The logarithmic attenuation rate was measured by the cantilever method for the laminated plates manufactured in the above Examples and Comparative Examples. For the rubber sheet peeled off from the laminate,
The visible light transmittance per mm was measured and its hue was observed. The results obtained are shown in Table 1 below.

Table 1 Item Example 1 Comparative example 1 Comparative example 2 Logarithmic attenuation rate 0.17 0.02 0.16 Light transmittance (%) 70 86 4 Hue Transparent / red Transparent / red Milky red Example 2 98 mol% and 2 of purified ethyl acrylate
-Hydroxybutyl acrylate 2 mol% solution-polymerized with benzoyl peroxide as a polymerization initiator to 100 parts of copolymer, powdered silica (average particle size 10 μm, n _D ; 1.45) 30 parts,
1 part of Spitblue and 4 parts of hexamethylene diisocyanate were added and it was homogeneously dissolved in methyl ethyl ketone with stirring.

The methyl ethyl ketone solution was uniformly coated on one side of a cold rolled steel plate of 0.4 mm in thickness, and after removing the solvent by drying, it was heated and pressed at 180 ° C for 30 minutes with a heat press to give a rubber thickness of 0.2 mm and a large size. A 50 × 100 mm laminated plate was produced.

Comparative Example 3 In Example 2, a laminated plate was manufactured without using powdered silica.

Comparative Example 4 In Example 2, the amount of powdered silica used was changed to 100 parts to produce a laminated plate.

The same measurements and observations as in Example 2 were performed on the laminated plates manufactured in Example 2 and Comparative Examples 3 to 4 described above. The results obtained are shown in Table 2 below.

Table 2 Item Example 2 Comparative example 3 Comparative example 4 Logarithmic attenuation rate 0.18 0.05 0.17 Light transmittance (%) 50 88 4 Hue Transparent / Blue Transparent / Blue Blue White Example 3 In Example 2, instead of powdered silica , The same amount (30
Part) powdery polymethylmethacrylate (average particle size 10μ
m) was used to produce laminates.

Comparative Examples 5 to 6 In Example 3, the amount of powdery polymethylmethacrylate used was changed to 2 parts (Comparative Example 5) or 90 parts (Comparative Example 6), respectively, to produce a laminate.

The same measurements and observations as in Example 1 were performed on the laminated plates manufactured in Example 3 and Comparative Examples 5 to 6 described above. The results obtained are shown in Table 3 below.

Table 3 Item Example 3 Comparative example 5 Comparative example 6 Log attenuation rate 0.30 0.09 0.28 Light transmittance (%) 52 64 3 Hue Transparent / blue Transparent / blue Blue-white

Claims (3)

[Claims] 1. (a) Alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and / or (b) 2 to 2 carbon atoms.
And an alkoxyalkyl acrylate having an alkoxyalkyl group of 8 and (c) at least one of the following monomers (a) epoxy group-containing vinyl monomer (b) carboxyl group-containing vinyl monomer (c) reactive halogen-containing vinyl Monomer (d) Diene monomer (e) Hydroxyl group-containing vinyl monomer (f) Amido group-containing vinyl monomer Copolymer of light-transmissive acrylic elastomer and refractive index n _D of 1.45 to 1.50 An acrylic elastomer composition containing the powdered poly (lower alkyl methacrylate) or silica. 2. The transparent acrylic elastomer is about 0.1 to 1
The acrylic elastomer composition according to claim 1, which is a copolymer obtained by copolymerizing 0 mol% of the component (c). 3. The acrylic elastomer composition according to claim 1, wherein about 5 to 50 parts by weight of a powdery material is used per 100 parts by weight of the light-transmitting acrylic elastomer.