JPH04342709A - New urethane compound its production and cocr0sslinking agent for acrylic rubber using the same - Google Patents

Abstract

PURPOSE:To obtain a new urethane compound, useful as a cocrosslinking agent for transparent acrylic rubber compositions and capable of providing crosslinked substances excellent in mechanical strength without causing unevenness of refractive index and clouding due to unreacted monomers, microphase separation, etc. CONSTITUTION:A compound expressed by the formula [R is dicyclopentenyl; (n) is 5-12]. The aforementioned compound is obtained by reacting a polymethylene diisocyanate expressed by the formula OCN(CH2)n NCO with hydroxydicyclopentadiene. The above-mentioned reaction is preferably carried out by using the polymethylene diisocyanate in an amount of 0.4-0.5 molar ratio based on the hydroxydicyclopentadiene and stirring the reaction mixture while heating the mixture at 60-80 deg.C.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides novel urethane compounds,
The present invention relates to a method for producing the same and a co-crosslinking agent for acrylic rubber using the same. More specifically, the present invention relates to a novel urethane compound that can be effectively used as a co-crosslinking agent for transparent acrylic rubber compositions, a method for producing the same, and a co-crosslinking agent for acrylic rubber using the same.

0002

[Prior Art] Japanese Patent Application Laid-Open No. 63-256902 states that
(Meth)acrylic acid ester whose ester group is an alkyl group, dicyclopentenyl group, etc. and the general formula CH2=CR
CO(OCH2CH2)nOCOCR=CH2[R:H
, CH3] and a di(meth)acrylate is described.

[0003] However, this synthetic resin optical transmission body, which is molded as a core material, is made by injecting the above-mentioned (meth)acrylic acid ester and di(meth)acrylate as a monomer mixture into a tube that becomes a cladding material. Because polymerization is heated and polymerized inside the tube, volumetric contraction occurs as the polymerization progresses, causing "sink marks" within the tube, causing the surface of the polymer that serves as the core material to lose its smoothness and the roundness to collapse. The same publication states that when injecting the monomer mixture, the pump must be injected at an extremely low rate, or the pump must be kept running for the purpose of pressurization.

[0004] Such polymerization operations are not only complicated, but also inevitably lead to heterogeneity due to gelation.
In addition, unreacted monomers clearly remain, and scattering associated with the non-uniform refractive index caused by this causes a problem in that the transparency of the light transmitting body is low.

[0005] Also, the applicant previously proposed that ethyl acrylate-dicyclopentenyl acrylate (molar ratio 90:10)
) A Fresnel lens is obtained by adding 10 parts by weight of tetraethylene glycol diacrylate and 0.5 parts of an organic peroxide (Perhexa 3M, a Nippon Oil & Fats product) to 100 parts by weight of the copolymer and cross-linking the product (Japanese Patent Application Laid-Open No. 3-6
Publication No. 501).

[0006] During crosslinking, the double bond of tetraethylene glycol diacrylate has higher reactivity than the double bond derived from the dicyclopentenyl group in the copolymer, so although the latter also co-crosslinks, , homopolymerization also proceeds considerably, reducing compatibility with the above-mentioned copolymers.

Such a decrease in compatibility tends to cause microphase separation, and this phenomenon is more likely to occur as the proportion of tetraethylene glycol diacrylate in the mixture increases. As a result, the crosslinked product not only causes uneven refractive index and cloudiness, scatters light and reduces transparency, but also becomes unsatisfactory in terms of mechanical strength such as tensile strength.

[0008]

[Problems to be Solved by the Invention] The object of the present invention is to provide a structure that does not cause uneven refractive index or cloudiness caused by the presence of unreacted monomers, gels, or microphase separation, and has excellent mechanical strength. It is an object of the present invention to provide a novel urethane compound that can be effectively used as a co-crosslinking agent for transparent acrylic rubber compositions to provide a crosslinked product, and a method for producing the same.

Another object of the present invention is to provide a co-crosslinking agent for acrylic rubber comprising such a novel urethane compound and a transparent acrylic rubber composition using the same.

0010

[Means for Solving the Problems] The present invention provides a novel urethane compound represented by the general formula ROCONH(CH2)nNHCOOR (where R is a dicyclopentenyl group and n is an integer from 5 to 12). provided.

Such new urethane compounds have the general formula OC
It is produced by reacting polymethylene diisocyanate represented by N(CH2)nNCO (where n is an integer from 5 to 12) and hydroxydicyclopentadiene. The reaction between the two uses polymethylene diisocyanate in an amount of about 0.4 to 0.5 in molar ratio to hydroxydicyclopentadiene, and
This is carried out by stirring while heating to 80°C. After the reaction is completed, the reaction mixture is dissolved in a solvent such as n-hexane or benzene, and the solution is subjected to silica column chromatography to remove unreacted raw material compounds, and the target diurethane compound is obtained by distilling off the solvent. obtain.

The obtained diurethane compound has an alkyl (
It is effectively used as a co-crosslinking agent for meth)acrylate-dicyclopentenyl group-containing (meth)acrylate copolymer rubber.

The alkyl (meth)acrylate-dicyclopentenyl group-containing (meth)acrylate copolymer includes alkyl (meth)acrylate and the general formula CH2=C
R1COOR2 or CH2=CR1COO(CH2)
dicyclopentenyl (meth)acrylate or dicyclopentenyloxyalkyl (wherein R1 is a hydrogen atom or a methyl group, R2 is a dicyclopentenyl group, and n is 1 or 2);
Copolymers with meth)acrylates are used.

The alkyl (meth)acrylate that forms the main component (approximately 60 to 94 mol%) of such a copolymer includes carbon atoms such as methyl, ethyl, n-butyl, isobutyl, 2-ethylhexyl, octyl, and dodecyl. 1-1
Alkyl acrylate having 2 alkyl groups or 6 to 6 carbon atoms such as hexyl, octyl, decyl, dodecyl, etc.
An alkyl methacrylate having 12 alkyl groups is used. The number of carbon atoms in methacrylate is limited to 6 or more because of the relationship with the glass transition point, and within the range where a copolymer exhibiting rubber-like elasticity at room temperature can be obtained, alkyl methacrylates with 5 or less carbon atoms can be used with 3 or more carbon atoms. There is no problem in copolymerizing more than the original.

[0015] The (meth)acrylates represented by the above two general formulas are copolymerized with these alkyl (meth)acrylates.
The acrylate is copolymerized as a crosslinking point-forming monomer in the copolymer in an amount of about 1 to 30% by weight, preferably about 5 to 20% by weight. In addition, in such a copolymer, a vinyl monomer copolymerizable with these comonomers, preferably alkyl methacrylate, etc. is contained in an amount of about 40 mol% or less, preferably about 4 to 2 mol%.
Copolymerization can also be carried out at a ratio of 0 mol%.

The copolymerization reaction is carried out by a solution polymerization method, an emulsion polymerization method, etc., but the solution polymerization method is most suitable since it is an essential condition that gelation does not occur. that time,
It is preferable to use a chain transfer agent typified by an organic mercapto compound in an amount of about 0.2 mol% or less based on the monomer mixture, as this effectively prevents gelation of the copolymer. Ru. After the polymerization reaction is completed, the copolymer is purified by a method such as reprecipitation to remove unreacted monomers, oligomers, and other impurities.

A diurethane compound represented by the above general formula is added to the copolymer as a co-crosslinking agent. Such a co-crosslinking agent has almost the same reactivity as the crosslinking group in the copolymer derived from the dicyclopentenyl group,
This prevents microphase separation due to homopolymerization of the co-crosslinking agent, that is, a decrease in transparency due to light scattering. The co-crosslinking agent has a molar ratio of about 0.5 to 2 to the crosslinking points in the copolymer.
．． 0, particularly preferably about 0.6 to 0.75.

A composition comprising a copolymer and a diurethane compound co-crosslinking agent is crosslinked by heating, irradiation with active energy rays, etc., and in this case, the crosslinking is generally performed using a crosslinking initiator, which is an organic peroxide. The crosslinking initiator is used in an amount of about 2 parts by weight or less per 100 parts by weight of the copolymer, but radicals are generated even without the use of a crosslinking initiator.
When a crosslinking reaction is carried out, a crosslinking initiator may not be used.

[0019]

[Effect of the invention] A copolymer of alkyl (meth)acrylate and dicyclopentenyl (meth)acrylate or dicyclopentenyloxyalkyl (meth)acrylate is co-crosslinked with a polyfunctional unsaturated compound, at which time a co-crosslinking agent By selecting a new diurethane compound that is less reactive than a diacrylate compound, a crosslinked acrylic rubber product with excellent transparency can be obtained by preventing microphase separation and light scattering due to cloudiness. Not only that, but also the mechanical strength (tensile strength, etc.) of the crosslinked product can be improved.

[0020]

[Example] Next, the present invention will be explained with reference to an example.

Reference Example 1 100 parts of a monomer consisting of 94 mol% ethyl acrylate and 6 mol% dicyclopentenyl acrylate (
(weight, same below), 1. azobisisobutyronitrile.
64 parts of mercaptoethanol, 0.9 parts of mercaptoethanol, and 721 parts of methyl ethyl ketone were added, and a polymerization reaction was carried out at 54° C. for 3 hours while bubbling nitrogen gas in a separable flask. After that, the polymerization reaction was stopped by cooling to below 5°C, and reprecipitation with 30% by weight methanol aqueous solution (poor solvent) and methyl ethyl ketone (good solvent) was repeated 5 times to remove unreacted monomers, etc. and binary copolymer A
I got it.

Reference Example 2 A polymerization reaction was carried out in the same manner as in Reference Example 1 using 100 parts of monomers consisting of 75 mol% n-butyl acrylate, 17 mol% methyl methacrylate and 8 mol% dicyclopentenyl acrylate. (However, the polymerization time was 8 hours), and ternary copolymer B was obtained.

Example 1 3.36 g of hexamethylene diisocyanate and 6.61 g of hydroxydicyclopentadiene were mixed,
The mixture was stirred for 6 hours while heating on a 0°C water bath. After cooling,
The reaction mixture was dissolved in n-hexane, and each raw material compound was removed by silica gel column chromatography (Rf: 0
．． 7 and 0.6), the target diurethane compound (n=6
) was obtained (55% yield) (Rf: 0.3). The infrared absorption spectrum of this room-temperature viscous compound is shown in FIG.

Binary copolymer A obtained in Reference Example 1
An acrylic rubber composition was prepared by adding 10 parts of this diurethane compound and 1 part of an organic peroxide (Nippon Oil Products Perhexa 3M) to 100 parts.
Compression molding was performed for minutes to obtain a transparent acrylic rubber sheet measuring 100 x 100 x 2 mm.

Example 2 In Example 1, instead of binary copolymer A, the same amount of terpolymer B obtained in Reference Example 2 was used.

Comparative Example 1 In Example 1, the same amount of tetraethylene glycol diacrylate was used instead of the diurethane compound, and 18
Compression molding was performed at 0° C. for 8 minutes to obtain a transparent acrylic rubber sheet.

Comparative Example 2 In Example 2, the same amount of tetraethylene glycol diacrylate was used instead of the diurethane compound, and 18
Compression molding was performed at 0° C. for 8 minutes to obtain a transparent acrylic rubber sheet.

The following measurements were carried out on the transparent acrylic rubber sheets obtained in each of the above Examples and Comparative Examples. Transparency: UV-VIS spectrophotometer (MPS manufactured by Shimadzu Corporation)
-2000) to measure the absorbance at a wavelength of 400 nm. Physical properties: tensile strength, elongation, and 100% modulus values were measured using an autograph (DSS-5000 manufactured by Shimadzu Corporation) according to JIS K-6301.

Measurement items
Real-1 Real-2 Ratio-1 Ratio-2
Transparency (ABS)
0.019 0.020 0.035 0.
036 Tensile strength (kgf/c
m2) 78 62 64
47 Elongation
(%) 185 170
215 206 100% modulus (kgf/cm2) 10.5 8
．． 4 12.3 9.6

[Brief explanation of drawings]

FIG. 1 is an infrared absorption spectrum of the diurethane compound obtained in Example 1.

Claims (4)

[Claims] Claim 1: General formula ROCONH(CH2)nNH
COOR (where R is a dicyclopentenyl group,
n is an integer of 5 to 12). 2. The method according to claim 1, characterized in that polymethylene diisocyanate represented by the general formula OCN(CH2)nNCO (where n is an integer from 5 to 12) and hydroxydicyclopentadiene are reacted. A method for producing a new urethane compound. 3. A co-crosslinking agent for alkyl (meth)acrylate-dicyclopentenyl group-containing (meth)acrylate copolymer rubber, comprising the novel urethane compound according to claim 1. 4. A transparent acrylic rubber composition comprising an alkyl (meth)acrylate-dicyclopentenyl group-containing (meth)acrylate copolymer and the novel urethane compound according to claim 1.