AU617447B2 - Process for preparing resins - Google Patents

Description

V

4~ 617447

COMPLETE

SPECIFICATION

FOR OFFICE U3E Application Number: Lodged: Class Int. Class Complete Specification Lodged: Accepted: xisd~ictC Published;: Priority: CX]2 bY t~ze S:.per- Related Art: 0,ji r~ o prii- To BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor/s: Address for Service: Complete S pecif ica tion MI~TSUI PETROCHEMICAL INDUSTRIES,

LTD.

2-5, Kasumigaseki 3-chome, Chiyoda-ku, Tokyo 100, Japan T(AKUTAROO KAUCHT.

SMITH SHELSTON BEADLE 207 .Riversdale R Ioad Box 410) Hawthorn, Victoria, Australia for the invention entitled: PROCESS FOR PREPARING RESINS The following statement is a full description of this invention, inC"*uding the best method of~ performing it known to /us: Page 1 Our Ref: #2825 PS:.MW:GD 32mit '4 0 00~ 0000 0 0~ Cd 0 1 00 0~ 0 0 0 J 0 0 0 0 00 00 0~ 0 0 0 0 00 0 0 00 0 0 0 00 00 0~ 0 o 0 0 000000 0 0 00 00 0 o 0 This invention relates to a process for preparing resins, and particularly, to a process for preparing cured resin moldings.

More particularly, it relates to a process for s preparing a cured resin molding by polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or (meth)acrylic compound as an essential ingredient whereby the molding has an equal hardness at the surface and jo interior, contains minimized strain, or b(,h of these properties.

In the polymerization of diethylene glycol diallyl carbonate, methyl methacrylate, and other monomers or oligomers, particulcrly in the presence of a variety of 15 radical polymerization initiators, if these reactants are in contact with oxygen in air or ambient atmosphere, the resulting polymers do not reach a high degree of polymerization and a sufficient hardness because radicals necessary for polymerization are consumed by oxygen.

For this reason, it is a common practice to carry out polymerization reaction of such reactants while shielding them from contact with air by means of a mold or the like.

When it is necessary to carry out polymerization with a certain or upper portion of the mold kept open to air in R consideratior of the shape of an end product or other factors, the surface of the polymerizing material in contact with air does not reach a sufficient degree of polymerization, forming (I viscous liquid or gel.

It is also adopted to carry out polymerization of monomers or oligomers while shielding the reactant surface by means of a resilient member. This method is difficult to apply to a complex shape of an end resin. Since a stress can be applied to the monomer or the like from the resilient member, optical distortion is induced in the resin. There S also remain problems of increased cost and low productivity.

Another problem in the prior art, diethylene glycol diallyl carbonate, methyl methacrylate, and an analogous monomer or oligomer is cast polymerized by casting the reactant into a mold and effecting polymerization therein.

)o Since the material contracts in volume upon polymerization, the mold configuration must follow the contracting volume as polymerization proceeds.

In carrying out polymerization of such monomers, a So resilient gasket or sheet is used to apply pressure to the o..o 1E mold such that the mold configuration may follow the "I contracting volume of the polymerizing material as disclosed o in Japanese Patent Application Kokai No. 57-207026.

0, ,n When monomers are polymerized by this method, however, o a stress is applied to the polymerizing material as described above from the exterior in the form of a resilient gasket or sheet, resulting in a resin having frozen strains.

v 3 0 °B Further, molding of resin in a conventional mold 00 suffers from a problem of inefficient operation because it is So often difficult to take out the molded resin from the mold at 0 the end of molding operation.

0o a $*SUMMARY OF THE INVENTION a0 0o An object of the present invention is to overcome the Sabove-mentioned problems of the prior art and to provide a process for preparing a resin by polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or a (meth)acrylic compound as an essential ingredient in a condition open to atmospheric air to form a cured resin molding whereby an optical distortion-free molding having a 3 very smooth surface and an equal hardness at the surface and interior can be obtained through a simple step and a complex shape of resin can be molded.

Another object of the present is to provide a process for preparing a cured resin molding whereby the molding containing less strain is obtained witt, ease of operation.

According to the present invention a process for preparing an optical distortion-free and a stress-free resin of which at least one surface is very smooth and has the same hardness as that of the interior thereof, 00 0 0 comprising the step of polymerizing a polymerizable liquid composition comprising a monomer or an a o 15 oligomer or a mixture thereof of a bis(allyl carbonate) 15 of an aliphatic, cycloaliphatic or aromatic dihydric ^C alcohol having the following formula CH -CH=CH2 (a) 06 00 CHCC I II2 (a 0 0 n t 0 &0 a wherein R is a residue of a dihydric alcohol, and n has 20 a value or an average value in the range of from 1 to 00 0 0 10, by placing a liquid or liquids having low solubility in and different density from the polymerizable liquid composition on the top or bottom surface of the polymerizable liquid composition said surface corresponding to said at least one surface of said resin.

Preferably, there is provided a process for preparing a resin, comprising polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or a (meth)acrylic compound as an essential ingredient -hile placing the polymerizable liquid composition containing monomer or oligomer or mixture on a liquid having low solubility in and TRA a higher density than the polymerizable liquid composition containing monomer or oligomer or mixture bc/10/2825mit.spe 91 9 3 In another preferred form, there is provided a process for preparing a resin, comprising polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or a (meth)acrylic compound as an essential ingredient while interposing the polymerizable liquid composition containing monomer or oligomer or mixture between a liquid having low solubility in and a higher 4 If f t a r 6 9 a

C.

'a~ bc/10/2825mit.spe 91 9 3 density than the polymerizable liquid composition containing monomer or oligomer or mixture and another liquid having low solubility in and a lower density than the polymerizable liquid composition containing monomer or S oligomer or mixture Preferably, the monomer or oligomer or mixture [A] contains'a monomer or an oligomer or a mixture thereof of a bis(allyl carbonate) of an aliphatic, cycloaliphatic or aromatic dihydric alcohol having the following formula 0 CH 2

=CH-CH

2 2

-CHCH

2 (a) II II 0 O n o wherein R is a residue of a dihydric alcohol, and n has a value or an average value in the range of from 1 to preferably fror 2 to Also preferably, liquid is a liquid synthetic 5 hydrocarbon polymer having a low molecular weight or a liquid hydrocarbon mixture or a mixture thereof.

Also preferably, liquid is an aqueous solution of a metal halide, a sulfate salt, a nitrate salt or a mixtue thereof.

The monomer or oligomer or mixture thereof containing a diallyl compound and/or (meth)acrylic compound as an essential ingredient used in the present disclosure encompasses a monomer alone, an oligomer alone, a mixture of a monomer and an oligomer, a mixture of two or more monomers, 2 a mixture of two or more oligomers, and a mixture of at least one monomer and at least one oligomer.

The polymer used in the present disclosure may be either a homopolymer or a copolymer, -L-l- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of one embodiment of the polymerization process according to the first aspect of the present invention.

S FIG. 2 is a schematic illustration of one embodiment of the polymerization process according to the second aspect of the present invention.

FIG. 3 is a schematic illustration of one embodiment of the polymerization process according to the third aspect of 'o the present invention.

DETAILED DESCRIPTION OF THE INVENTION The invention will be described in detail.

o Referring to FIG. 1, there is illustrated one preferred o° embodiment of the process for preparing a resin according to the first aspect of the present invention.

The resin preparing process of the present invention is a process for polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixtue thereof containing a diallyl compound and/or a (meth)acrylic compound S-o as an essential ingredient. The monomer or oligomer or mixture is simply referred to as hereinafter. As shewn in FIG. 1, the [Al-containing polymerizable liquid q" composition is polymerized while placing a liquid having low solubility in the [A]-containing polymerizable liquid .s composition and a lower density than the [A]-containing S polymerizable liquid composition on the [A]-containing polymerizable liquid composition.

Component to be polymerized by the polymerizing or curing process of the present invention is a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or (meth)acrylic compound as an essential ingredient.

The diallyl compound used in is not particularly limited as long as it falls in the group of diallyl compounds. Examples of the diallyl compounds include

(Z

b uon oooa on o a o oo u i i! o A composition comprising a monomer or an oligomer or a mixture thereof of a di(allyl carbonate) of an aliphatic, cycloaliphatic or aromatic dihydric alcohol having the general formula:

CH

2

=CH-CH

2 -O-C-O R-O-C-O CH 2

-CH=CH

2 II ii 0 0 n wherein R is a residue of a dihydric alcohol, and n has a value or an average value in the range of from 1 to preferably from 2 to In the composition, preferred component is a \D reaction product of diallyl carbonate and a dihydric alcohol in a molar rati. of 4:1 or lcwer, more preferably in a molar ratio of 2:1. Preferred examples of the dihydric alcohol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, S,5 dipropylene glycol, propylene glycol, neopentyl glycol, trimethylpentane diol, cyclohexane dimethanol, bis(hydroxymethyl)tricyclodecane, 2,7-norbornane diol, C,c'-xylene diol, 1,I-bhis(hydroxyethoxybenzene), and 2,2-bis[4-(hydroxyethoxy)phenyl]propane alone and mixtures thereof.

In the practice of the present invention, the preferred diallyl compound is EVIII'1 a liquid bis(allyl carbonate) composition comprising components and shown below. Reference is made to Japanese Patent Application Kokai No, 59-140214.

The preferred liquid bis(ally' carbonate) composition e .,w o D J o i o Ot u 9 comprises 10 to 90% by weight of an oligomer or a mixture of ollgomers of a bis(allyl carbonate) of an aliphatic, cycloaliphatic or aromatic dihydric alcohol having the general formula: CH2=CH-CH 2 -O-C-O R-o-C-O CH 2 -CH=cH2 0 0 n _1_IYC _I 7 wherein R is a residue of a dihydric alcohol, and n has a value or an average value in the range of from 2 to 10, with the proviso that the content of a dihydric alcohol bis(allyl carbonate) monomer optionally present in the oligomer is up to 50% by weight; 0 to 90% by weight of a compound selected from the group consisting of a monomeric bis- or tris(allyl carbonate) of an al,.phatic, cycloaliphatic or aromatic di- or trihydric alcohol having the general formula: R O-C-0-GH2-CH-CH 2 0 n t:o wherein R' is a residue of a di- or trihydric alcohol, and n' is equal to 2 or 3, or a mixture thereof, with the proviso that the content of an oligomeric bis(allyl carbonate) of a S di- or trihydric alcohol or a poly(allyl carbonate) of a dior trihydric alcohol optionally present in the monomer or the mixture is up to 30% by weight, an allyl ester of an aliphatic or aromatic di- or tricarboxylic acid having the general formula: R"--C--CH2-CH=CH 2 I II S* 0 n" o wherein R" is a residue of a di- or tricarboxylic acid, and n" is equal to 2 or 3, and triallyl cyanurate and S triallyl isocyanurate; and 0 to 30% by weight of an acrylic or vinyl monomer; with the proviso that the total of components and is more than 0.

The preferred component is a reaction product of diallyl carbonate and a dihydric alcohol in a molar ratio of 4:1 or lower, more preferably in a molar ratio of 2;1. The dihydric alcohol is preferably selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1, 6-hexanediol, diethylene glycol, polyethylene glycol, d,'ipropylene glycol, propylene glycol, neopentyl glycol, s- trimethylpentane diol, cyclohexane dimet'hanol, bis(hydroxyrnethyl)tricyclodecane, 2, 7-norbornane dial, ca,cX-xylene diol, 1, 4-bis (hydroxyethoxybenzene), and 2, 2-bis E4- (hydroxyethoxy) phenyl) propane.

The preferred component is a reaction product of iO) diallyl carbonate and a di- or trihydric alcohol in a molar ratio of 6:1 or higher, more preferably in a molair ratio of 12:1. The di- or trihydric alcohol is preferably selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, IS polyethylene glycol, dipropylene glycol, propylene glycol, neopentyl glycol, trimethylpentane diol, cycloheXane dimethanol, bis (hydroxymethyl) tric clodecane, 2, 7-norb:ornane diol, cL,ca-xylene diol, 1,4-bis(hydroxyet'hox<ybenzene), 2,2bis (hydroxyethoxy) phenyl] propane, trimethylol propane, and z.o tri(hydroxyethyl) isocyanurate alone and mixtures thereof.

Also incl~uded in component are diallyl phthalate, c.,allyl succinate, diallyl adipate, diallyl chlorendate, diallyl glycolate, diallyl naphthalene dicarboxylate, atnd triallyl mellitate.

Component is preferably selected fromx vinyl acetate, vinyl benzoate, methyl methacrylatet phenyl methacrylate, methyl acrylate, methyl tnaleata, maleic anhydri&F, and vinylidene chloride alone and mixtures thereof.

so Another examples of the diallyl compounds include; (I]1 a copolymerizable com'position comprising a diallyE ester of a nuclearly halo-6ubstituted benzene dicarboxylic, acid and diethylene glycol diallyl carbonate as disclosed in Japanqse Patent Application Kokai No, 59-45312; -~iI [III a copolymerizable composition comprising at least one ester of a nucleerly halo-substituted benzene dicarboxylic acid (for example, bisallyl 2,4-dichloroterephthalate) and at least one radical-polymerizable monofunctional monomer bearing an aromatic ring and capable of forming a homopolymer having a refractive index of at least 1.55 (for example, phenyl methacrylate as disclosed in Japanese Patent Application Kokai No, 59-8709; (III] a copolymerizable composition comprising at least Sone bisallyl carbonate or bis-p-methylallyl carbonate (for example, 1,4-bis(hydroxyethoxy)benzene bisallyl carbonate) and at least one radical-polymerizable monofunctional monomer bearing an aromatic ring and capable of forming a homopolymer having a refractive index of at least 1.55 (for exampla, Sphenyl methacrylate) as disclosed in Japanese Patent Application Kokai No. 59-8710; [IV) a copolymerizable composition comprising a monomer obtained by reacting a monool (for example, 4-benzyl-phenol) with an unsaturated carboxylic acid or chloride thereof (for Sexample, acrylic acid or chloride thereof) and a radicalpolymerizable monomer capable of forming a homopolymer having a refractive index of at least 1,55 (for example, styrene) as disclosed in Japanese Patent Application Kokai No. 59-96109; o(V a copolymerizable composition comprising a 0-6 chlorobenzoic acid allyl ester (for example, 21,3dichlorobenzoic acid diallyl ester) and a difct ional monomer (for example, tetrabromophthalic acid diallyl ester) as disclosed in Japaese Patent Application Kokai No. 59- 96113; 1o (VII a copolymerizable composition as disclosed in Japanese Patent Application Xokai No. 59-184210; (VIt) diethylene glycol bisallyl carbonate; and (VIII) copolymerizable compositions of a bisallyl compound such as diethylenes glycol bisallyl carbonate, 1,4- Sbis(hydroxyethoxy)benzene bisallyl carbonate, and 2,4dichlorotercphthalic acid bisallyl ester and a vinyl monomer having an aromatic ring such as phenyl methacrylate and benzyl methacrylate.

'i1'e (meth)acrylic compounds used as are not particularly limited although mono(meth)acrylates and di(meth)acrylates of the following general structural formulae, x K CH2-C-C-O-C-Y-O-C-C-CH2 11 II 0 0 Wherein; X=CH3, Br, Cl, or H and Y is a divalent \0 radical.

The following compound are preferred, especially the di(meth)acrylates are preferred.

_i i C H 2 =CH-CO- (OCH 2

-CH

2 )1 n1-6

CH

2 =CH-CO-(C C 2 -ck 2 n -OCH 3 n=3- 9 COO H

RKCOOCH.

2

CH.

2 OCOCH.=C1I 2

COOH

~~COOCH (Cl-b CH2 OCOCH=CH 2

CH

2

=CH-COOCH

2 Cl-H 2 OCOC H 2 Cl-H 2 -CO0 0H Cl- 2 =CH-CO-- (OCH- 2 Cu 2 2 (CH 2

-CH

0

II

CH

2

(OCH

2

-CH-

2

-OC-

n '=2-23 12 CH3 .H 00c COOCH 2 C H 2

OCOC=CH

2

CH

3 (cH 2 7 CH 2 0 O CH 3

CH

2 C li 2 OC C =CH 2

OH

3

OH

CH

2

=C-CO-O-CH

2

-CH-CH

2 C-a

CH

3

CH

2 =CCOOC H 3 13

CH

3

CH

3 I I C H 2 =c-CO- (OCH 2

-C!

2 )n-O-CO-C=CH 2 n=1 -2 3

CH

3 0 0 CH 3 C H 2 =C-C-0-CH-CH 2 -C H 2 -0-CC=CH 2 C H 3 0 0 C H 3 C H 2 =C-C 0 (CH 2 5 O -C-C=C.H 2 C H 3 0 C H 3 0 CH3

CF

2

=C-C--CH

2 -C-CH"0-C-C=CH 2

CF!

3

C

14 CH3c H 3

CH

3 I I I

CR

2 =t-CO-O- (cM-cH 2 0) -CO-C=CH 2 n 9 C1 2 (OCn 2

-CH

2

CH

3 m n -2-30 C H 3 0OH CM 3

CH

2 =C-CO-O--CH2 -CH-CH 2

-O-CO-C=CH

2

CMH

2 H- C0-0 (CH 2 -C H 2 0) CO-CH=CH 2 n=4-:1 4 r-

CH

2 =CH-COO- (CH 2 8OOC-CH=CH 2

CH

3

CH

2 =CH-CO-O- (CH-CH 2 0) -CO-CH=CH 2 1-9

CH

3

CH

2 -CH000- (CH 2 CH20) 67 c~

CH

3 m +n -2 C~s OH I I

CH

2

=C-CO-O-CH

2 -CH- CH 2

-O-CO-CH=CH

2 o 000 00 00 CH3 GH2-CH-CO-f(Oil2 dHO) 0-0(oHco) I-O-CH-CH 2 m+ 4~3 C, 0~) 00 000 0 00~00 0000 0* "0 00 '4 C' 00 0 0 0 00 C 0 000 1 CC 0

CI

<C 'C C 0 0 0 0 .3 CI 0 0 'CC 00 0 0 CCCI 00 t 0

CH

2 -CH-'CO (CH 2

CH

2

O)

CH

2 -CH-COO- (C 2

CH

2

O)

CU

3

CH

2 -CH-COO- (GH 2

CHO)

s~ q(CH 2

CH

2 O) n-C0-CH-CH 2 x x 0 CH 3 11 1 s o- (CU 2 CHO) n-CO-CH-CH 2 I 0 m+n'~3 X X X halogen

CH

3

A

C u (CH 2

CH

2 0) n--C-CHC 2

CH

3 m n 2 X X halogen L i' I_.

The [A]-containing polymerizable liquid composition may further contain a polymerization initiator.

In the practice of the present invention, the polymerization initiator used in polymerizing the S containing polymerizable liquid composition is not particularly limited insofar as it does not adversely affect the clarity, color and other properties of the resulting resin. It may be any of photo polymerization initiators, thermal polymerization initiators, and photo and thermal o1 polymerization initiators.

The photo polymerization initiators include electron beam and radiation polymerization initiators as well as photo polymerization initiators.

Soi A typical example of the photo polymerization initiator 15 is 2-hydroxy-2-methyl-l-phenyl-propan-l-one.

.o Examples of the thermal polymerization initiators include peroxydicarbonates such as diisopropyl peroxy- Sdicarbonate, di-sec-butyl peroxydicarbonate, dicyclohexyl Speroxydicarbonate, and tert-butyl perbenzoate; organic ;m peroxides such as benzoyl peroxide, acetyl peroxide, terto.o butyl hydroperoxide, cumene hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, lauroyl peroxide, oD diisopropyl peroxydicarbonate, dimethyl ethyl ketone peroxide, and diacyl peroxide; and radical initiators such as azobisisobutyronitrile and azobisraethylisovaleronitrile.

A typical example of the photo and thermal polymerization initiators is the compound eOf the following formula: 0 0 0 (t-Bu) 00 4h9 -L (t-Bu) (t-Bu) -00-C C-00- (t-Bu) 0 1 0 0 i i i The polymerization initiator may be used in an amount of 0.1 to 10% by weight, preferably 1 to 6% by weight based on the [A]-containing polymerizable liquid composition.

The [Al-containig polymerizable liquid composition may further contain another monomer and a filler in such amounts that they do not detract from the physical properties of the resulting polymer. For example, a mono (meth)acrylic compound, di(meth)acrylic compound, or unsaturated carboxylic acid such as maleic anhydride may be added in an amount of up o to 30% by weight, or a silane coupling agent such as vinyl triethoxysilane may be added in an amount of up to 10% by weight, based on the weight of the polymer.

The density of the [A]-containing polymerizable liquid composition is not particularly limited although it is s generally of the order of from 0.9 to 1.2 g/cm3.

It is to be noted that as the [A]-containing polymerizable liquid composition, use may also preferably made of a prepolymer which is obtained by pre-polymerizing the composition with a polymerization initiator to such an zo extent that the composition may sustain fluidity.

In the polymerization process of the present invention, S' the [A]-containing polymerizable liquid composition is polymerized, preferably in the presence of a polymerization initiator, while a liquid having low solubility in the S 5 ([A]-containing polymerizable liquid composition and a lower density than the (A]-containing polymerizable liquid composition is present on the [A]-containing polymerizable liquid composition as schematically illustrated in FIG, 1.

The liquid is not particularly limited as long as so it is less soluble in the (A]-containing polymerizable liquid composition and has a lower density than the containing polymerizable liquid composition.

The solubility of liquid in the [A]-containing polymerizable liquid composition should be low enough to i avoid any adverse influence on the clarity, weatherability, i LIsurface and other properties of the resulting resin. More illustratively, the solubility is generally up to preferably up to 2%.

Better results are obtained in that hardness or degree of polymerization is equal between the surface and the interior of the resulting resin when the solubility falls within this range.

The density of liquid is not particularly limited although it is generally up to 1, preferably of the order of \0 from 0.8 to 0.95.

Liquid is preferably a liquid synthetic, hydrocarbon polymer having a low molecular weight or a liquid hydrocarbon mixture or a mixture thereof.

o 7% Examples of the synthetic hydrocarbon polymers include Is poly(a-olefin) oils such as polydecene-l, alkyl aromatic oils such as alkylbenzenes, polybutene oil or liquid polybutene, polyhexene, alkylnaphthene oils suc(h as 2, 4-dicyclohexyl-2methylpentane oil, and ethylene-a-Olefin random copolymer p* 't oils such as ethylene-propylene random copolymer oil, -o Preferred among them are those having a molecular weight of at least 500, more preferably from 1,000 to 10,000.

0 *Also preferred are ethylene-a-olefin random copolymer 0 oils having a number average molecular weight (Mn) of from 500 to 5,000, especially from 1,500 to 3,000.

S S Particularly preferred are liquid, low-molecular weight ethylene-a-olefin random copolymers consisting of 30 to mol% of ethylene units and 30 to 70 mol% of a-olefin units a'o and having a number average molecular weight; (Mn) of from 1,000 to 5,000 and a Q value (weight average molecular weight/number average molecular weight) of up to 3. When liquid is a liquid polyolefin or the lik, the liquid itself exhibits mold release effect, considerably facilitating mold release operation. At the end of polymerization, the liquid polyole 'in may be readily removed with an organic sS solvent such as hexi ne, kerosene, and trichloroethylene.

CH

2

=CH-CH

2 R-O-C-0 CH 2

-CH=CH

2 0 0 n Also water may preferably be used as liquid Water is amenable to polymerization at relatively low temperatures because of its high vapor presoure.

Liquid at the surface may be covered with an inert gas atmosphere having an oxygen concentration of up to 1% while polymerization is carried out. This ensures better results in that there is obtained a resin having a higher surface hardness.

The polymerization process of the present invention is by polymerizing the [A]-containing polymerizable liquid composition while the liquid having low solubility in the (A]-containing polymerizable liquid composition and a lower density than the [A)-containing polymerizable liquid composition is present on the (A]-containing polymerizable IS liquid composition.

Means for placing liquid on the (A]-containing S" polymerizable liquid composition may be any desired means o although the following procedure is preferred.

SAn open-top mold 10 is charged with the [A]-containing 0o polymerizable liquid composition along with a polymerization initiator. Liquid is then poured on the upper interface or surface of the [A]-containing polymerizable liquid composition to shield the (A]-containing polymerizable liquid composition from contact with air (oxygen)..

o* p The order of adding the liquids preferably starts from a higher density liquid as described above. It is possible to form a layer of liquid on a layer of the containing polymerizable liquid composition by first pouring liquid into the mold 10 and then pouring the containing polymerizable liquid composition with a careful control to avoid suspension between liquids.

The mold 10 used in the polymerization process of the present invention may be of any commonly used materials including glass, polyvinyl chloride, polyethylene resin, polypropylene resin, and poly(4-methyl-l-pentene) resin.

The configuration of the mold 10 may be properly chosen depending on the shape of an end product to be molded.

Polymerization may be carried out under various conditions depending on a particular [A]-containing s polymerizable liquid composition and the identity of polymerization initiator.

In the case of thermal polymerization, the composition may be heated in a heating tank to a temperature of about to 150 0 C, preferably about 40 to 120°C for about 1/2 to 72 io hours, preferably about 1 to 4 hours, although the exact value will vary with the xhape and size. In the case of photo polymerization, polymerization may be carried out under a high-pressure mercury lamp with a power of 60 to 150 W/cm for about 1 minute to 2 hours, preferably 3 to 30 minutes at a temperature of about 40 to 120°C, preferably about 60 to 0- 1000C.

S

J o The cured resin molding obtained by the process of the present invention has no substantial difference in hardness 3 between the surface and the interior and is free of optical o- distortion in the interior. It may be widely utilized as optical lens, light-transmitting plates and rods.

0 SReferring to FIG.2, there is illustrated one preferred 0 embodiment of the process for preparing a resin according to the second aspect of the present invention.

S; The process for preparing a resin according to the present invention is by polymerizing a polymerizable liquid composition containing [Al a monomer of an oligomer or a ao mixture thereof containing a diallyl compound and/or a (meth) acrylic compound as an essential ingredient. The o monomer or oligomer or mixture is simply referred to as hereinafter. As shown in FIG. 2, the ([A-containing polymerizable liquid composition is polymerized while it is present on [B1 a liquid having low solubility in the containing polymerizable liquid composition and a higher 3 -i density than the tA]-containing polymerizable liquid composition.

Component to be polymerized by the polymerizing ocuring process of the present invention is a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or (meth)acrylic compound as an essential ingredient.

The diallyl compound used in is not particularly limited as long as it falls in the group of diallyl compounds. Examples of the diallyl compounds include the io same compounds described above.

The [A]-containing polymerizable liquid composition may further contain a polymerization initiator.

In the practice of the present invention, the o polymerization initiator used in polymerizing the is containing polymerizable liquid composition is not particularly limited insofar as it coes not adversely affect o the clarity, color and other properties of the resulting oo resin. It may be any of photo polymerization initiators, iSo" thermal polymerization initiators, and photo and thermal polymerization initiators.

The photo polymerization initiators include electron Sbeam and radiation polymerization initiators as well as photo 0 polymerization initiators.

A typical example of the photo polymerization initiator s and the thermal polymerization initiators are the same chemical compositions described above.

The polymerization initiator may be used in an amount of 0.1 to 10% by weight, preferably 1 to 6% by weight based on the [Al-containing polymerizable liquid composition.

o0 The [Al-containing polymerizable liquid composition may further contain another monomer and a filler in such amounts that they do not detract from the physical properties of the resulting polymer. For example, a mono (meth)acrylic compound, di(meth)acrylic compound, or unsaturated carboxylic ,S acid such as maleic aohydride may be added in an amount of up to 30% by weight, or a silane coupling agent such as vinyl triethoxysilane may be added in an amoun: of up to 10% by weight, based on the weight of the polymer.

The density of the [A]-containing polymerizable liquid G composition is not particularly limited although it is generally of the order of from 0.9 to 1.2 g/cm3.

It is to be noted that as the [A]-containing polymerizable liquid composition, use may also preferably be made of a prepolymer which is obtained by pre-polymerizing i0 the composition with a polymerization initiator to such an extent that the composition may sustain fluidity.

In the polymerization process of the present invention, the [A]-containing polymerizable liquid composition is polymerized, preferably in the presence of a polymerization 5 initiator, while the [A]-containing polymerizable liquid 'o composition is present on a liquid having low solubility SS in the [A]-containing polymerizable liquid composition and a ro higher density than the [A]-containing polymerizable liquid composition as shown in FIG. 2.

2O Liquid is not particularly limited as long as it is less soluble in the [A]-containing polymerizable liquid composition and has a higher density than the [A',-containing polymerizable liquid composition.

The solubility of liquid in the [A]-containing is polymerizable liquid composition should be low enough to avoid any adverse influence on the clarity, weatherability, surface and other properties of the resulting resin, More illustratively, the solubility is generally up to preferably up to 3%.

:so Better results are obtained with respect to the resin surface hardness when the solubility falls within this range.

The density of liquid is not particularly limited although it is generally at least 1.1, preferably of the order of from I.I1 to Preferred examples of liquid include aqueous solutions of metal halides, sulfate salts and nitrate salts, the concentration of the inorganic salt being controlled such that the solution may have a higher density than the containing polymerizable liquid composition. Also included are mercury and other metals which are liquid at r.om temperature.

In polymerizing the [A]-containing polymerizable liquid composition according to the process of the present ID invention, the [A]-containing polymerizable liquid composition is present on a liquid having low solubility in the [A]-containing polymerizable liquid composition and a higher density than the [A]-containing polymerizable liquid composition.

The [A]-containing polymerizable liquid composition may S' be placed on liquid by any methods, but generally by o* admitting the [A]-containing polymerizable liquid composition S containing a polymerization initiator into a mold 10 which 1 d has been charged with liquid .1 The [A]-containing polymerizable liquid composition is polymerized in the thus established system consisting of two layers of liquid [B]/(A]-containing polymerizable liquid composition as shown in FIG. 2.

o The order of adding the [A]-containing polymerizable s liquid composition and liquid preferably starts from a higher density liquid as described above. It is possible to form a layer of (A]-containing polymerizable liquid o composition on liquid by previously admitting the containing polymerizable liquid composition into the mold and then admitting liquid with a careful control to avoid suspension.

The mold 10 used in the polymerization process of the present invention may be of any commonly used materials including glass, polyvinyl chloride, polyethylene resin, aS polypropylene resin, and poly(4-methyl-l-pentene) resin.

The configuration of the mold 10 may be properly chosen depending on the shape of an end product to be molded.

Polymerization may be carried out under various conditions depending on a particular [A]-containing t polymerizable liquid composition and the identity of polymerization initiator.

In the case of thermal polymerization, the composition may be heated in a heating tank to a temperature of about to 150'C, preferably about 40 to 1200C for about 1/2 to 72 1o hours, preferably about 1 to 4 hours, although the exact value will vary with the shape and size. In the case of photo polymerization, polymerization may be carried out under a high-pressure mercury lamp with a power of 60 to 150 W/cm for about 1 minute to 2 hours, preferably 3 to 30 minutes at a temperature of about 40 to 1200C, preferably about 60 to 100C.

The resin obtained by the polymerization process of the present invention is free of optical, distortion and may be widely utilized as optical lens, light-transmitting plates ac and rods.

It is readily taken out of the mold with an advantage of easy operation.

Referring to FIG. 3, there is illustrated one preferred embodiment of the process for preparing a resin according to .s the third aspect of the present invantion.

The process for preparing a resin according to the present invention is by polymerizing a polymerizable liquid composition containing a monomer or an oligomer or a mixture thereof containing a diallyl compound and/or a ZO (meth)acrylic compound as an essential ingredient. The monomer or ligomer or mixture is simply referred to as hereinafter. As shown in FIG. 3, the [Al-containinq polymerizable liquid composition is polymerized while interpOsing it between a liquid having low solubility in Z and a higher density than the tA]-containing polymerizable 26 liquid composition and another liquid having low solubility in and a lower density than the A])-containing polymerizable liquid composition.

Component to be polymerized by the polymerizing or curing process of the present invention is a monomer or an oligomer or a mixture thereof containing a dallyl compound and/or (meth)acrylic compound as an essential ingredient.

The diallyl compound uved in is not particularly limited as long as it falls in the group of diallyl ,o compounds. Examples of the dially3 compounds include the same compounds describr.d before.

The [A]-containing polymerizable liquid composition may further contain a polymerization initiator.

In the practice of the present invention, the 15 polymerization initiator us in polymerizing the [Alcontaining polymerizable liquid composition is not particularly limited insofar as it does not adversely affect the clarity, color and other properties of the resulting resin. It may be any of photo polymerization initiators, LO thermal polymerization initiators, and photo and thermal polymerization initiators.

The photo eslymerization initiators include electron beam and radiation polymerization initiators as well as photo polymerization initiators, 1s A typical example of the photo polymerization initiator and the thermal. polymerization initiators are the same o chemicl- compositions described above.

The polym.rization initiator may be used in an amount of 0.1 to 10% by weight, preferably I to 6% by weight based so on the tAI-containing polymerizable liquid composition.

The [Al-containing polymerizable liquid composition may further contain another monomer and a filler in such amounts that they do not detract from the physical properties of the resulting polymetr For example, a mono (meth)acrylic z4 compound, di(meth) acrylic compound, or unsaturated carboxylic IYL YLli ~i ;~C 27 acid such as maleic anhydride may be added in an amount of up to 30% by weight, or a silane coupling agent such as vinyl triethoxysilane may be added in an amount of up to 10% by weight, based on the weight of the polymer.

SThe density of the [A]-containing polymerizable liquid composition is not particularly limited although it is generally of the order of from 0.9 to 1.2 g/cm3.

It is to be noted that the (A]-containing polymerizable liquid composition is preferably used in the form of a prepolymer which is obtained by pre-polymerizing the composition with a polymerization initiator to such an extent that the composition may sustain fluidity.

In the polymerization process of the present invention, 0 the [A]-containing polymerizable liquid composition is 1S polymerized, preferably in the presence of a polymerization initiator, while the composition is interposed between a liquid having low solubility in and a higher density than the [A]-containing polymerizable liquid composition and (C] another liquid having low solubility in and a lower density a0 than the [A]-containing polymerizable liquid composition as schematically illustrated in FIG. 3, S"o Liquid is not particularly limited as long as it is less soluble in the [A]-containing polymerizable liquid composition and has a higher density than the [A]-containing as polymerizable liquid composition as described before, The other liquid is not particularly limited as long as it is less soluble in the [A]-containing polymerizable liquid composition and has a lower density than the (A]-containing polymerizable liquid composition as so described before.

Liquid at the surface may also be covexed with an inert gas atmosphere having an oxygen concentratior of up to 1% while polymerization is carried out. This ensues better results in that there is obtained a resin having a higher 3S surface hardness.

a 28 The process of the present invention is by polymerizing the [A]-containing polymerizable liquid composition while the composition is interposed between liquid having low solubility in and a higher density than the [A]-containing s polymerizable liquid composition and the other liquid [C] having low solubility in and a lower density than the containing polymerizable liquid composition.

Means for interposing the [A]-containing polymerizable liquid composition between liquids and may be any desired means although the following procedure is preferred.

A mold 10 is charged with liquid the containing polymerizable liquid composition is then poured into the mold along with a polymerization initiator, and thereafter liquid is poured into the mold. There results o a reaction system of three layers, A] -containing o6 °o polymerizable liquid composit,'on/[C] as shown in FIG. 3. The S[A] -containing polymerizable liquid composition is o polymerized in this system.

The order of adding the liquids preferably starts from D a higher density liquid to a lower density liquid as S described above. It is possible to first add liquids and o',o into the mold 10 with a careful control made to avoid suspension between the liquids, and then pour the o" containing polymerizable liquid composition so as to form a layer of the [A]-contairing polymerizable liquid composition between layers of liquids and These components may be added in another different order.

The mold 10 used in the polymerization process of the present invention may be the same materials as described 3o before.

Polymerization may be carried out under various conditions depending on a particular. [A]-containing polymerizable liquid composition and the identity of polymerization initiator. In the case of thernm olymerization, the composition may be heated in a heating L.nk to a i -C temperature of about 30 to 150 0 C, preferably about 40 to 120 0 C for about 1/2 to 72 hours, preferably about 1 to 4 hours, although the exact: value will vary with the shape and size. In the case of photo polymerization, polymerization may be carried out under a high-pressure mercury lamp with a power of 60 to 150 W/cm for about 1 minute to 2 hours, preferably 3 to 30 minutes at a temperature of about 40 to 120 0 C, preferably about 60 to 100 0

C.

The resin obtained by the process of the present o0 invention is a stress-free, homogeneous polymer having good surface smoothness and no substantial difference in hardness between the surface and the interior. It may be widely utilized as optical lens, light-transmitting plates and rods.

o Examples oo 5 Examples of the present invention are given below by way of illustration and not by way of limitation.

o Example 1 0 0 4 The following composition, 25.8 grams, was poured into a beaker having an inner diameter of 5 cm as the A] a -o containing polymerizable liquid composition.

[A1-containina polymerizable liuid composition 1 o' The reaction product obtained by reacting diallyl carbonate with diethylene glycol in a molar ratio of 2:1 in the presence of sodium ethoxide under the Z6 I conditions described in Japanese Patent Application Kokai No. 56-133246 (consisting of 30% by weight of diethylene glycol bisallyl carbonate and 70% by weight of oligo-carbonate, n 3 to 10) 55% by weight Tris (allyl carbonate) of tris (hydroxyethyl) isocyanurate obtained by reacting dially carbonate with tris(hydroxyethyl) isocyanurate in a molar ratio of 12:1 12.4% by weight Diethylene glycol bisallyl carbonate 27.5% by weight Vinyl acetate 5% by weight Diisopropyl peroxydicarbonate 2.5% by weight Liquid in the form of an ethylene-propylene s copolymer having a density of 0.846 (Mn 2500, Q 2.0) was poured on [A]-containing polymerizable liquid composition 1 to a layer thickness of 1 cm.

The beaker with the two-layer charge was placed in an air oven and heated stepwise from 40 0 C to 850C over 5 hours, io completing polymerization of [A]-containing polymerizable liquid composition 1.

The resulting resin had a fully hardened surface as Sdemonstrated by a pencil hardness of 3H and a density of 1.331.

SoUV s An observation with a polariscope showed that the resin involved very little optical distortion. The resin was S determined for surface roughness using a surface roughness meter (manufactured by Sanpo Mfg. With a measurement length of 0.75 mm, the measurements were Ra 0.002 Jm and Rmax 2 0.03 Im, indicating good surface smoothness.

Example 2 Polymerization of [A]-containing polymerizable liquid composition 1 was completed by the same procedure as in Example 1 except that the layer thickness of liquid was 2-s changed to 0.2 cm.

o The resulting resin had a fully hardened surface as demonstrated by a pencil hardness of 3H and a density of 1.330.

An observation with a polariscope showed that the resin a0 involved very little optical distortion. The resin was determined for surface roughness using a surface roughness meter (manufactured by Sanpo Mfg. With a measurement -j .rCi T"C length of 0.75 mm, the measurements were Ra 0.003 |Lm and Rmax 0.05 Lm, indicating good surface smoothness.

Example 3 The! following composition was poured into a beaker S having an inner diameter of 5 cm to a layer thickness of 0.8 cm as the [A]-containing polymerizable liquid composition.

[Al-containing polymerizable liquid composition 2 000 0 00- DO 0~ 0 Ua 0 C 0 The reaction product obtained by reacting diallyl carbonate with diethylene glycol in a molar ratio of 2:1 in the presence of sodium ethoxide under the conditions described in Japanese Patent Application Kokai No. 56-133246 (consisting of 70% by weight of diethylene glycol bisallyl carbonate and 30% by weight of oligo-carbonate, n =1 3 to 7) 58% by weight Tris(allyl carbonate) 6f tris(hydroxyethyl) isocyanurate obtained by reacting dially carbonate with tris(hydroxyethyl) isocyanurate in a molar ratio of 12:1 13% by weight Diethylene glycol bisallyl carbonate n 0* o 0 20 0 f D i3i 29% by weight 2.7% by weight Diisopropyl peroxydicarbonate a 00 0 ~j V~ no0 Liquid in the form of an ethylene-propylene copolymer having a density of 0.846 (Mn 2500, Q 2.0) was then added to a layer thickness of 0.5 cm.

S2. The beaker with the two-layer charge was placed in an air oven and heated stepwise from 40°C to 85 0 C over 5 hours, completing polymerization of [A]-containing polymerizable liquid composition 2.

The resulting resin had a fully hardened surface as demonstrated by a pencil hardness of 3H and a density of 1.340.

i i An observation with a polariscope showed that the resin involved very little optical distortion. The resin was determined for surface roughness using a surface roughness meter (manufactured by Sanpo Mfg. With a measurement length of 12.5 mm, the measurements were Ra 0.03 Lim and Rmax 0.3 Im, indicating good surface smoothness.

Example 4 The following composition was poured into a beaker having an inner diameter of 5 cm to a layer thickness lO of 0.8 cm as the [A]-containing polymerizable liquid composition.

S [Al-containinga olymerizable liquid comoosition 3 A monomer of the formula: CHs CH3 I I 0 CH 2

O-CH

2 H012) 4-0-G-C0-H2 II II 0 0' i having a viscosity of 14 centipoise at 250C, a .o saponification value of 340, and a bromine value of 93 99.5% by weight Benzoyl peroxide 0.5% by weight Density: 1.08 g/cm3 Liquid in the form of an ethylene-propylene n copolymer having a density of 0.846 (Mn 2500, Q 2.0) was added to a layer thickness of 2.0 cm.

The beaker with the two-layer charge was placed in an air oven, and heated at 88°C for 6 hours and then at 100°C for another 2 hours.

The resulting resin had a pencil hardness of 3H both at the upper and lower surfaces, and a density of 1.2250.

L-fep 33 An observation with a polariscope showed that the resin involved very little optical distortion. Good surface smoothness was also observed.

Example A beaker having an inner diameter of 15 cm was charged with liquid in the form of an aqueous solution of magnesium chloride adjusted to a density of 1.30 to a depth of about 3 cm. Then the [A)-containing polymerizable liquid composition 1 described before was poured into the beaker to o1 a layer thickness of 4 cm.

04 4 1 U 00 j 441 Cn 4 '0 4 0'4 04 4 4 S00 44 i 40a (0l s is The beaker with the two-layer charge was placed in an air oven and then heated stepwise from 30 C to 90'C over 7 days, completing polymerization of [A]-containing polymerizable liquid composition 1.

The resulting resin had fully polymerized as demonstrated by a pencil hardness of 3H and a density of 1.336. Using a polariscope, the resin was obsrrved to involve very little optical distortion. The resin was readily taken out of the beaker ensuring efficient operation.

zo Example 6 A beaker having an inner diameter of 5 cm was charged with liquid in the form of an aqueous solution of zinc chloride adjusted to a density of 1.29 to a depth of about 3 cm. Then the [A]-containing polymerizable liquid composition ZS 2 as described before was poured into the beaker to a layer thickness of 4 cm.

The beaker with the two-layer charge was placed in an air oven and heated stepwise from 40°C to 80°C over 5 hours, completing polymerization of [A]-containing polymerizable o liquid composition 2.

The resulting resin had fully polymerized as demonstrated by a pencil hardness of 3H and a density of 1.340. Using a polariscope, the resin was observed to 1 i I- C -i-Yinvolve very little optical distortion. The resin was readily taken out of the beaker ensuring efficient operation.

Example 7 A 50-nl beaker having an inner diameter of 5 cm was charged with liquid in the form of an aqueous solution of magnesium chloride adjusted to a density of 1.28 to a depth of about 5 mm. Then the [A]-containing polymerizable liquid composition 3 as described before was poured to a layer thickness of 4 cm.

O0 The beaker with two-layer charge was placed in an air oven and then heated at 850C for 5 hours.

The resulting resin had a pencil hardness of 3H both at the upper and lower surfaces, and a density of 1.255. An observation with a polariscope showed that the resin involved s very little optical distortion. The resin was readily taken out of the beaker ensuring efficient operation.

Example 8 A beaker having an inner diameter of 15 cm was charged with liquid in the form of an aqueous solution of magnesium chloride adjusted to a density of 1.30 g/cm3 to a o depth of about 3 cm. Then the [A]-containing polymerizable o liquid composition 1 as described before was poured into the beaker to a layer thickness of 4 cm.

i"o Thereafter, liquid in the form of an ethylenepropylene copolymer having a density of 0.846 g/cm3 (Mn 2500, Q 2.0) was added to a layer thickness of 2 cm.

.n The beaker with the three-layer charge was placed in an 0 air oven and heated stepwise from 30°C to 90'C over 7 days, completing polymerization of [A]-containing polymerizable liquid composition 1.

The resulting resin had a thickness of 43.9 mm, a diameter of 141 mm, a pencil hardness of 3H both at the upper and lower surfaces, and a density of 1.336 g/cm3. Using a polarisaope, the resin was observed to involve very little optical distortion. Using a surface roughness meter (manufactured by Sanpo Mfg. the resin was determined for surface roughness. With a measurement length of 12.5 mm, the measurements were Ra 0.03 pm and Rmax 0.3 pLm at the upper surface and Ra 0.05 pm and Rmax 1.1 p.m at the lower surface, indicating good surface smoothness.

Example 9 A beaker having an inner diameter of 5 cm was charged with liquid in the form of an aqueous solution of zinc chloride adjusted to a density of 1.29 to a depth of about 3 cm. Then the [A]-containing polymerizable liquid composition 2 as described before was poured into the beaker to a layer thickness of 4 cm.

Thereafter, liquid in the form of an ethyleneo propylene copolymer having a density of 0.846 g/cm3 (Mn 2500, Q 2.0) was added to a layer thickness of 1.0 cm.

The beaker with the three-layer charge was placed in an air oven and heated stepwise from 400C to 80°C over 5 hours, completing polymerization of [A]-containing polymerizable liquid composition 2.

The resulting resin had a pencil hardness of 3H at the upper surface and 4H at the lower surface, and a density of 1.340 g/cm3. An observation with a polariscope showed that the resin involved very little optical distortion. Good surface smoothness was also observed.

5, Example SA stainless steel vat of 40 cm by 30 cm by 7 cm (deep) was charged With liquid in the form of an aqueous solution magnesium chloride adjusted to a density of 1.30 g/cm3 to a depth of about 3 cm. Then 1440 grams of the containing polymerizable liquid composition 1 as described before was added. Thereafter, liquid in the form of an ethylene-propylene copolymer having a density of 0.846 g/cm 3 (Mn 2500, Q 2.0) was added to a layer thickness of 1 cm.

The vat was placed and secured in a water tank, whose temperature was raised stepwise from I0C to 85'C. After 7 hours, the polymerized resin plate was taken out. The plate was dipped in hexane to dissolve away liquid entrained on s the surface thereof.

The resulting resin plate had a pencil hardness of 3H both at the upper and lower surfaces and a density of 1.336 g/cm3. An observation with a polariscope showed that the resin plate involved very little optical distortion. Using a kO surface roughness meter (manufactured by Sanpo Mfg. the resin was determined for surface roughness. With a measurement length of 0.75 mm, the measurements were Ra 0,002 gm and Rmax 0.03 gm at the upper surface and Ra 0.002 Lm and Rmax 0.10 m at the lower surface, indicating good surface smoothness.

Example IU A 50-ml beaker having an inner diameter of 5 cm was charged with liquid in the form of an aqueous solution of magnesium chloride adjusted to a density of 1.28 g/cm 3 to a depth of about 5 mm* Then the (A]-containing polymerizable liquid composition 3 as described before was poured into the beaker to a layer thickness of 4 cm.

Thereafter, liquid in the form of an ethylenepropylene copolymer having a density of 0.846 g/cM 3 (Mn 2500, u Q 2,0) was added to a layer thickness of 2.0 cm.

The beaker with the three-layer charge was placed in an air oven, and heated at 85 0 C for 5 hours and then at 90°C for another 5 hours, The resulting resin had a pencil hardness of 3H both at the upper and lower surfaces, =nd a density of 1,255 g/cm3.

An cibservation with a polariscope showed that the resin involved very little optical distortion. Good surface smoothness was also observed.

37 In polymerizing a monomer or oligomer or mixture containing a diallyl compound and/or a (meth)acrylic compound as an essential, ingredient in a partially open mold to form a cured resin molding, the resin preparing process of the first 6 aspect of the present invention enables to produce a molding having a high surface hardness at a low cost through a simple step.

Since the surface of the monomer or oligomer or mixture is shielded from air or oxygen by a specific liquid, a io complex shape may be readily molded and shielding from air is ensured to follow shrinkage in volume with polymerization.

There is obtained a strain-free resin since no stress is externally applied during polymerization from a mold or A resilient member.

The resin preparing process of the second aspect of the present invention ensures that a resin having minimized internal strain is obtained because shrinkage takes place evenly during polvyrqerization without externally applying stress.

At the end of polymerization, the resin can be readily removed from the mold, ensuring ease of operation.

According to the resin preparing process of the third aspect of the present Invention, shrinkage takes place evenly during polymerization because no stress is externally ,z6 applied. There is obtained a resin having little internal strain.

An end molded product having parallel opposed surfaces can be readily formed by polymerization without the necessity to form a mold assembly from a glass mold and a gasket, or au the necessity to remove the mold.

A sufficient hardness is reached at both the surface and the interior of the resin.

The claims form part of the disclosure of this specification.

Claims (6)

1. A process for preparing -n opti:ca. distortion- free and a stress-free resin of which at least one surface is very smooth and has the same hardness as that of the interior thereof, comprising the step of polymerizing a polymerizable liquid composition [A] comprising a monomer or an oligomer or a mixture thereof of a bis(allyl carbonate) of an aliphatic, cycloaliphatic or aromatic dihydric alcohol having the following formula CH CH,-CH=CH, (a) II 0 ]n wherein R is a residue of a dihydric alcohol, and n has a value or an average value in the range of from 1 to 10, by placing a liquid or liquids having low solubility in and different density from the polymerizable liquid composition on the top or bottom surface of the polymerizable liquid composition said surface Scorresponding to said at least one surface of said resin.

2. A process as set forth in claim i wherein said liquid to be placed on the top surface of the polymerizable liquid composition is a liquid (to be referred as liquid hereinafter) having a lower density than the polymerizable liquid composition

3. A process as set forth in claim 2 wherein said liquid is a liquid synthetic hydrocarbon polymer having a low molecular weight or a liquid hydrocarbon mixtute or a mixture thereof.

4. A process as set forth in claim 1 wherein said liquid to be placed on the bottom surface of the polymerizable liquid composition is a liquid (to be *AO h referred as liquid hereinafter) having a higher i density than the polymerizable liquid composition bc/10/2825mit.spe 91 9 3 39 A process a. set forth in claim 4 wherein the liquid CE] is an aqueous solution of a metal halide, a sulfate salt, a nitrate salt or a mixture thereof.

6. A process as set forth in claim 1 wherein the liquids to be pla ed on the top surface of the polymerizable liquid composition is liquid (to be re4,rred as liquid hereinafter) having a lower density than the polymerizable liquid composition [A] and the liquid to be placed on the bottom surface of the polynerizable liquid composition is a liquid (to be referred as liquid hereinafter) having a higher density than the polymerizable liquid composition respectively.

7. A process for preparing a resin according to any one of claims 1 to 10 substantially as hereinbefore described. DATED this 3 September 1991 CARTER SMITH BEADLE Fellows Irntitute of Patent Attorneys of Australia Patent Attorneys for the Applicant: MZTSUI PETROCHEMICAL INDUSTRIES LIMITED bc/10/2825mit.spe 91 9 3