JP3061065B2 - Method for cross-linking transparent acrylic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transparent acrylic elastomer.
The present invention relates to a method for crosslinking a tomer composition . More specifically, the present invention relates to a method for cross-linking a transparent acrylic elastomer composition in which a decrease in transparency upon heating of a cross-linked product is effectively prevented.

[0002]

2. Description of the Related Art Generally, acrylic elastomers having high transparency have a low crosslinking reaction rate, and the addition of a crosslinking accelerator or the like results in a decrease in transparency and cannot be used, resulting in poor productivity. The problem was seen.

[0003] Therefore, when an acrylic elastomer having a hydrocarbon unsaturated group having high reactivity is used, gelation occurs at the time of polymerization of the acrylic elastomer, and there is a problem that an elastomer cannot be obtained in a high yield. That is, when the copolymerization ratio of the hydrocarbon -unsaturated group-containing monomer is increased, gelation is likely to occur, which lowers the polymer yield and lowers the transparency. Therefore, when the copolymerization ratio is reduced, a decrease in physical properties is observed this time.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to increase the productivity governed by the rate of the crosslinking reaction, and to effectively prevent a decrease in the transparency of the crosslinked product upon heating, thereby achieving a rubber-like elasticity. It is an object of the present invention to provide a method for crosslinking a transparent acrylic elastomer composition which can be used in the field of a transparent material molded article having the following.

[0005]

[0006]

[Means for Solving the Problems]The object of the present invention is to
(a)hydrocarbonUnsaturated group and (b) hydroxyl group, epoxy group,
It is a ruboxyl group, a reactive halogen group or an amide group
Acrylic elastomer with functional group, organic peroxide
And a transparent agent containing a crosslinking agent for the functional group.
Ril elastomer compositionWas first peroxide crosslinked.
After that, a crosslinking method for crosslinking with a crosslinking agent to the functional group
Achieved by

[0007]

The main component of the acrylic elastomer is the number of carbon atoms
An alkyl acrylate having 1 to 8 alkyl groups and
And / or an alkoxyalkyl acrylate having an alkoxyalkyl group having 2 to 8 carbon atoms. These acrylates comprise about 60-98% by weight, preferably about 7
It is copolymerized at a rate of 0 to 94% by weight.

The remaining about 40 to 2% by weight, preferably about 30 to
6% by weight is occupied by the hydrocarbon -unsaturated group-containing monomer and the various functional group-containing monomers, both of which are used at a ratio of about 5 to 95% by weight.

[0010] Examples of the monomer containing a hydrocarbon unsaturated group include:
Dicyclopentenyl (meth) acrylate, divinylbenzene, pentadiene, vinylcyclohexene, butadiene, cyclopentadiene, methylbutadiene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di
(Meth) acrylate [oligomer] and the like are used. These monomers are cross-linked by organic peroxides such as benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, and tertiary butyl peroxide.

Further, the above-mentioned various functional group-containing monomers and a method for crosslinking them are as follows, for example.

(1) Hydroxyl group-containing vinyl monomer: hydroxyalkyl (meth) acrylate, hydroxyalkoxy acrylate, N-methylol acrylamide, etc.

These copolymers are crosslinked by a crosslinking agent such as polyisocyanate such as hexamethylene diisocyanate or a trimer thereof, polycarboxylic acid such as adipic acid, or alkoxymethylmelamine such as methoxymethylmelamine.

(2) Epoxy group-containing vinyl monomers such as allyl glycidyl ether and glycidyl (meth) acrylate

[0015] These copolymers are prepared by a polyamine such as diethylenetriamine or m-phenylenediamine, a polycarboxylic acid such as adipic acid, an acid anhydride such as phthalic anhydride or maleic anhydride, or a crosslinking agent such as polyamide or sulfonamide. Cross-linked

(3) Carboxyl group-containing vinyl monomer Acrylic acid, methacrylic acid, itaconic acid, etc.

These copolymers are cross-linked by a cross-linking agent such as polyepoxide such as ethylene glycol diglycidyl ether, 1,4-butanediol and 1,1,1-trimethylolpropane.

[0018] (4) reactive halogen-containing vinyl monomer 2-chloroethyl vinyl ether, monochloroacetic acid vinyl <br/> etc.

These copolymers are cross-linked by a cross-linking agent such as polyamine such as diethylenetriamine and polycarbamate.

(5) Amide group-containing vinyl monomers such as acrylamide and methacrylamide

Crosslinked by a crosslinking agent such as polyisocyanate such as aminoformaldehyde, hexamethylene diisocyanate or trimer thereof.

The above-mentioned copolymerization reaction of each monomer component is generally carried out by a radical polymerization method, and a solution polymerization method is preferred from the viewpoint of transparency and suppression of gelation.

The obtained acrylic elastomer containing two kinds of crosslinkable groups has about 0.01 to 50 parts by weight, preferably about 0.1 to 20 parts by weight, of the organic peroxide and the functional group per 100 parts by weight thereof. Crosslinking agents for the groups are added and other desired ingredients, such as (reactive) fillers, plasticizers,
After blending an antioxidant and the like within a range that does not impair the transparency, it is subjected to molding such as casting, compression, and injection in a molding die.

The cross-linking reaction is carried out in two stages, first heated to the decomposition temperature of the organic peroxide, peroxide cross-linking of hydrocarbon unsaturated bonds is performed in the mold, and then partial cross-linking removed from the mold The object is heated, such as in an oven, and the functional groups are crosslinked by the crosslinking agent.

[0025]

The acrylic elastomer used in the present invention has a hydrocarbon unsaturated group having a higher cross-linking reactivity and a functional group having a lower cross-linking reactivity.
Compared to a case where only a monomer having a hydrocarbon unsaturated group is copolymerized, it is obtained in terms of yield and transparency.

The cross-linking of the carbon
When the hydride unsaturated group is crosslinked, it is taken out of the molding die, and then a less reactive functional group is put in an oven or the like, and can be crosslinked only by heating. Time is greatly reduced and productivity is significantly improved.

Further, cross-linked product obtained by such a two-stage crosslinking process are also prevented reduced effectively transparent when further heated, to such a transparent material molded article having a resulting rubber-like elastic Ensure use.

[0028]

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

Example 1 Ethyl acrylate 94 parts by weight Dicyclopentenyl acrylate 3 2-Hydroxyethyl acrylate 3 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. The reaction was carried out (polymerization rate: 82%). Thereafter, reprecipitation was repeated five times using a mixed solvent of n-hexane-methylethylketone (10: 1) to obtain a terpolymer.

To 100 parts by weight of the obtained terpolymer, 0.05 parts by weight of lauroyl peroxide and 4 parts by weight of hexamethylene diisocyanate were added, and this composition was placed in a stainless steel mold (50 × 50 × 5 mm). And put at 80 ° C for 15
Compression molding for 10 minutes to perform peroxide crosslinking, and then 10 minutes.
It was placed in an oven at 0 ° C. and heated for 4 hours to effect crosslinking by isocyanate groups.

Example 2 90 parts by weight of ethyl acrylate Dicyclopentenyl acrylate 4 Glycidyl acrylate 6 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. (Polymerization rate 89%). Thereafter, reprecipitation was repeated five times using a mixed solvent of n-hexane-methylethylketone (10: 1) to obtain a terpolymer.

To 100 parts by weight of the obtained terpolymer, 0.06 parts by weight of an organic peroxide (Perhexa 3M Nippon Oil and Fat Products) and 5 parts by weight of phthalic anhydride were added, and the composition was placed in a stainless steel mold. (50 × 50 × 5 mm), compression molded at 120 ° C. for 5 minutes to perform crosslinking by peroxide, and then 140 ° C.
And heated for 4 hours to perform crosslinking by an anhydrous carboxyl group.

Example 3 Ethyl acrylate 93 parts by weight Dicyclopentenyl acrylate 4 Methacrylamide 3 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. (Polymerization rate 76%). Thereafter, reprecipitation was repeated five times using a mixed solvent of n-hexane-methylethylketone (10: 1) to obtain a terpolymer.

To 100 parts by weight of the obtained terpolymer, 0.05 parts by weight of lauroyl peroxide and 4 parts by weight of hexamethylene diisocyanate were added, and the composition was placed in a stainless steel mold (50 × 50 × 5 mm). And compression-molded at 80 ° C for 5 minutes to perform peroxide crosslinking, and then 80 ° C
And heated for 30 hours to perform crosslinking by isocyanate groups.

Example 4 93 parts by weight of n-butyl acrylate Dicyclopentenyl acrylate 3 2-Chloroethyl vinyl ether 4 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was subjected to bubbling with nitrogen gas at 52 ° C. for about 3 hours. A copolymerization reaction was performed (polymerization ratio: 68%). Thereafter, reprecipitation was repeated five times using a mixed solvent of n-hexane-methylethylketone (10: 1) to obtain a terpolymer.

To 100 parts by weight of the obtained copolymer, 0.05 parts by weight of tertiary butyl peroxide and diethylene triamine
4 parts by weight were added, and the composition was placed in a stainless steel mold (50 × 50 × 5 mm), compression-molded at 120 ° C. for 8 minutes, crosslinked with peroxide, and then placed in an oven at 80 ° C. And heated for 30 hours to effect crosslinking with amino groups.

Example 5 92 parts by weight of 2-methoxyethyl acrylate Dicyclopentenyl acrylate 3 Methacrylic acid 5 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. The reaction was carried out (polymerization rate: 72%). Thereafter, reprecipitation was repeated five times using a mixed solvent of n-hexane-methylethylketone (10: 1) to obtain a terpolymer.

To 100 parts by weight of the obtained copolymer, 0.05 parts by weight of tertiary butyl peroxide and 6 parts by weight of ethylene glycol diglycidyl ether were added, and this composition was added to a stainless steel mold (50 × 50 × 5 mm). ), 120 ℃
For 8 minutes to carry out crosslinking by peroxide, then put in an oven at 80 ° C. and heated for 30 hours to carry out crosslinking by epoxy group.

COMPARATIVE EXAMPLE 1 Ethyl acrylate 94 parts by weight Dicyclopentenyl acrylate 6 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. After about 1.5 hours, gelation began to occur.

Comparative Example 2 The copolymerization reaction of Comparative Example 1 was stopped for 1 hour and 25 minutes and reprecipitated in the same manner as in each Example to obtain a binary copolymer (polymerization rate)
38%).

To 100 parts by weight of the obtained copolymer, 0.1 part by weight of lauroyl peroxide was added, and the composition was placed in a stainless steel mold (50 × 50 × 5 mm) and compression-molded at 80 ° C. for 5 minutes. did.

Comparative Example 3 Ethyl acrylate 96 parts by weight 2-Hydroxyethyl acrylate 4 Azobisisobutyronitrile 0.05 Methyl ethyl ketone 100 The above mixture was copolymerized at 52 ° C. for about 3 hours while bubbling with nitrogen gas. Reprecipitation treatment was performed in the same manner as in the example to obtain a binary copolymer (polymerization rate: 80%).

8 parts by weight of hexamethylene diisocyanate was added to 100 parts by weight of the obtained copolymer, and the composition was placed in a stainless steel mold (50 × 50 × 5 mm) and compression-molded at 80 ° C. It took 8 hours to be able to remove it.

The crosslinked sheets obtained in each of the above Examples and Comparative Examples were placed in an air oven at 130 ° C.
After standing for a while, the light transmittance (400 nm) was measured before and after heating using a UV-VIS spectrometer (MPS-2000, manufactured by Shimadzu Corporation), and the following results were obtained.

[0045] The crosslinked sheet of Comparative Example 2 was colored slightly yellow after heating.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08J 3/24 C08L 33/06 C08L 33/14

Claims (2)

(57) [Claims] (1) (a) a hydrocarbon unsaturated group and (b) a hydroxyl group,
An acrylic elastomer having a functional group that is an epoxy group, a carboxyl group, a reactive halogen group or an amide group, an organic peroxide and a transparent acrylic elastomer composition containing a cross-linking agent for the functional group ,
After cross-linking with a compound, cross-linking with a cross-linking agent to a functional group
Cross-linking method . 2. The method according to claim 2, wherein the peroxide crosslinking is carried out in a molding die.
Crosslinking of functional groups on partially crosslinked products removed from molds
The method according to claim 1, wherein the crosslinking is performed.