CA2045207A1 - Paper surface treating agent - Google Patents
Paper surface treating agentInfo
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- CA2045207A1 CA2045207A1 CA 2045207 CA2045207A CA2045207A1 CA 2045207 A1 CA2045207 A1 CA 2045207A1 CA 2045207 CA2045207 CA 2045207 CA 2045207 A CA2045207 A CA 2045207A CA 2045207 A1 CA2045207 A1 CA 2045207A1
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Abstract
VI. ABSTRACT OF THE DISCLOSURE
The present invention provides a paper surface treating agent and is characterized in that its active ingredient is a copolymer which is prepared by emulsification polymerization of a monomer composition comprising a number of monomers in a given ratio in the presence of an anionic emulsifier and which has a glass transition temperature of over 80°C.
Using the paper surface treating agent according to the present invention yields a coat with fine pores on the surface of paper to provide an excellent gloss thereon and offers good printing ink set to improve the printability.
The present invention provides a paper surface treating agent and is characterized in that its active ingredient is a copolymer which is prepared by emulsification polymerization of a monomer composition comprising a number of monomers in a given ratio in the presence of an anionic emulsifier and which has a glass transition temperature of over 80°C.
Using the paper surface treating agent according to the present invention yields a coat with fine pores on the surface of paper to provide an excellent gloss thereon and offers good printing ink set to improve the printability.
Description
2 ~ 2 ~ rl I, TITI.E OF T~E INVENTION
PAPER S~RFACE~ TREATING AG:13NT
II. BACKGRO[~ND OF THE INVENTION
The present invention relakes to a paper surface trea~ing agent which provide~ a high gloss for the surface of printing paper and which offers a good ink adherence upon printing, ~ enerally, glossy paper is made by forming a coat on the surface of paper with a dispersion of pigment in a binder such as a water-soluble or waker-dispersible high molecular polymer latex and subseguently subject-ing the paper to calendering, Anothex method of glossy paper making is to coat paper with resin. Speciflcally, a resin coat film is formed on the surface of paper by coating a molten solution of resin or a water-soluble or water-dispersible resin, III . SUMMARY OF THE INVENTION
However, the ~ormer me~hod, in which paper is coated with a dispersed pigment in binder and calen-dered, does not always ofer a satisfactory gloss, requiring specially designed equipmenk such as a cast coater to obtain higher glossO
As for the latter method, in which paper is coated with resin, it has a disadvantage that the obtained coated paper is unsuitable for use as printing paper because of poor ink absorption and slow ink drying in the printing process~ though a high gloss is obtained.
The present invention was developed to solve these problems. It ~rovides a paper surface treating agent which provides an excellent gloss for the surface of paper and which offers a good surface condition with high printability for printing paper.
Accordingly, the paper surface treating agent of the present invention is characterized in that its active ingredient is a copolymer emulsion prepared by emulsification polymerization of a monomer composition of 70 to 99 w~ styrene and/or methyl methacrylate, 1 to 10 wt% water-soluble monomer and not more than 29 wt% of other copolymerizable oil-soluble monomers (figures for percent r~tio are relative to the total amount o the monomers subjected to emulsification polymerization) in the presence of an anionic emul~
sifier wherein the copolymer in said copolymer emulsion has a glass transition temperature of over 80~C.
The monomer composition which constitutes the copolymer of the present invention incorporates styrene and/or methyl methacrylate as the major component. In the present invention, styrene and methyl methacryIate are equivalent to each other; they may be used singly or in combination. lt is preerable, however, that ~he weight ratio of styrene and methyl methacrylate be 7:3 to 3:7 from the viewpoint of preventing roll staining upon heat roll treatment and adjusting ink set in offset printing.
The ratio of styrene and/or methyl methacrylate in the monomer composition, i.e., in the copolymer is preferably 70 to 99 wt%, more preferably 85 to 99 wt%.
If the ratio is below this range, the glass transition temperature of the copolymer decreases, and even if the glass transition temperature an be increased, then the printability is degraded because blocking occurs upon calendering after coating and because emulsion grains show excess aggre~ation in a molten state to form a tight film-like coat.
Examples of water-soluble monomers which can be used to compose the copolymer of the present invention include mono or dicarboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid, hydroxy compounds such as hydroxyethyl methacrylate, hydroxypropyl meth-acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate, methacrylamide, acrylamide and sty renesulfonate. These water-soluble monomers may be used singly or in combination.
The ratio of the water-soluble monomers used should he 1 to 10 wt%. The ratio should be over 1 wt%
Eor the stabilization of the copolymer emulsion, but if it exceeds 10 wt%, ink setting upon printing is degraded because exaess emulsion grains aggrega~ion in a molten state occurs during drying as the surface of the emulsion grains becomes water-soluble and the outer portion o~ the emulsion grains becomes more water-soluble.
In addition to the styrenetand or methyl methacrylate and water-soluble monomers described above, a copolymerizable oil-soluble monomer can be added as a monomer composition at not more than 29 wt~
to constitute the copolymer of the present invention if necessary. Although the Xind of the copolymerizable oil-soluble monomer is not subject to limitation, a monomer showing a glass transition temperature of over 40OC when it is prepared as a homopolymer is preferred.
Bxamples of suitable monomers include ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, a-methyl styrene, vinyl toluene, acrylonitrile, methacrylonitrile and crosslinkable monomers such as glycidyl methacrylate and divinylbenzene.
The copolymer of the present invention is prepared by emulsification polymerization of the monomer compo-sition described above in the presence of an anionic 2 3 ''JL ~1 'J1 ~ P
emulsiier, The anionic emulsifier for emulsification polymerization o the monomer composition is one or more anionic emulsifiers selected from the group comprising ordinary anionic emulsifiers, anionic reactive emulsifiers and anionic high molecular emulsifiers, Examples of the ordinary anionic emulsifier used here include higher alcohol sulfates, alkylbenzen-esulfonates, aliphatic sulfonates, dialkylsulfo-succinates, alkylnaphthalenesulfonates, alkyldiphenyl ether disulfonates, polyoxyethylene alkyl ether sulfates and polyoxyethylene alkylphenol ether sulfates~
lS Examples of ~h~ anionic reactive emulsifier include reactive emulsifiers containing a phosphats group prepared by the addition of 8 mol on avexage of ethylene oxide to acrylic acid in accordance with a conventional method followed by reaction with phosphoric anhydride; ammonium salt of allylnonylphenol polyethylene oxide ~10 mol) adduct sulate, acrylic acid or methacrylic acid derivatives and reactive emulsifiers containin~ an allyl group, Examples of the high molecular emulsifier include 2S ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid~ itaconic acid, maleic acid and fumaric acid, and homopolymer salts of a monomer containing a sulonic acid group, such as styrenesulfonic acid and 2-acrylamide-2-methyl-propanesulfonic acid and allylalkylsulfosuccinic acid.
It is also possible to u~e copolymers of an ethyl enically unsaturated carboxylic acid monomer described above or its salt or a monomer containing a sulfonic acid group described above or its salt and an aromatic unsaturated monomer such as styrene, ~-methylstyrene or vinyltoluene or an alkyl ester of acrylic acid or methacrylic acid such as ethyl ~meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or dodecyl (meth)acrylate, The average molecular weight of these high molecular emulsifiers is preferably about 2000 to 1 100000.
The copolymer of the present invention should have a glass transition temperature of over 80C. I the glass transi.tion temperature is below 80C, blocking or roll staining ocaurs upon hot calendering after coating, and the absorbability and dryability of print-ing ink are degraded because the emulsion grains aggregate in a molten state to form a coat upon hot pressurization.
The paper surface treating agent of the present invention can be prepared by a conventional method such as the method in which water, the emulsifier described ~3 ~ rl abov~ and star~ing monomers axe mi~ed and then polymerized with heating in the presence of a polymerization initiator such as a persulfate, peroxy compound or azobis compound, and the method in which S polymerization is carried out in the presence of a redox catalyst such as a combination of a persulfate or peroxide and iron salt, ascorbic acid, sulfite or the like. It is unnecessary to add an inorganic pigment to the copolymer component during preparation.
The paper surface treating agent of the present invention can be coated on uncoated paper such as wood-free paper or moderate quality paper or coated paper, particularly on coat paper and on coated paper undercoated with a small amount of an aqueous resin such as polyvinyl alcohol, polyacrylamide or anokher water-soluble resin for the purpose of filling by various coating methods.
The coating composi~ion may contain according ~o the necessity a mold release agent, a water-soluble resin such as casein or starch, a colorant and other additives in small amounts, as long as the gloss is not degraded.
After coating, the paper is dried under ordinary conditions for coat paper making, ater which it is subjected to super calendering or gloss calendering, which offers a high gloss, a~ temperatures below 80C, r~ rl whereby highly printable qlossy paper which has a high gloss and which does not cause roll staining or blocking is obtained.
The paper surface treating agen~ of the present invention, unlike the prior art surface treating agents for glossy paper, is not accompanied by film-like coating of grains by complete aggregation in a molten state because its glass transition temperature is as hiyh as over 80C. In addition, calendering after coating and drying yields a coat of partially aggre-gated emulsion grains, resulting in the formation of a coat having fine pores.
Thereore, fine hard grains form a smooth coat on the surface of coated paper to give a high gloss, and blocking is not liable to occur. Furthermore, ink absorbability upon printing is good because a large number of fine pores are present on the surface of the coat. With these favorable features, excellent printability is obtained unlike the conventional glossy paper.
It is evident that the paper surface treating agent o the present invention, which comprises a copolymer emulsion, when used to improve the paper surface properties, offers high levels of white paper ~5 gloss, printing gloss and excellent ink set which are discrived after. Also, the paper subjected to surface f.,~l ~
treatment wlth the paper surface treating agent of the present invention, even when not subjec~ed to calendering, is capable of having a level of whit~
gloss nearly equal to that commercially available 5 calendered coat paper.
IV. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
~ he present invention is hereinafter described in more detail by means of the following esamples. In the description below, "part(s)" and "%" mean "part~s~ by weight" and "wt~", respectively.
Examples 1 To a reactor equlpped with a stirrer, a dripping tank and a thermometer, 300 g of water and emulsifiers, specifically 9 parts of ammonium polyo~yethylene ~n =
10) nonylphenol ether sulfate and 4 parts of disodium nonyldiphenyl ether disulfonate, were charged, and they were mixed therein.
To this mixture, 60 parts of a monomer mixture prepared by mixing 100 par~s of styrene, 10 parts of ~-methylstyrene, 76 parts of methyl methacrylate and 10parts of methacrylic acid was added, and the tempera-ture was increased to 60C while replacing the inside atmosphere with nitrogenO While keeping this tempera-ture, 7.2 parts of a 20% aqueous solution of ammonium 2 ~ 7 persulfate and 4.8 parts of a 20% aqueous solution of anhydrous sodium bisulfite were added as a redo~
catalyst, followed by polymerization ~or 1 hour.
After adding 10 parts of a 20~ aqueous solution of ammonium persulfate, the remaining 140 parts of the monomer mixture described above was added dropwise over a period of L hour. Then, the temperature was increased to 90C, and reaction ended after keeping the temperature at 900C for 4 hours~
After completing o the reaction, aqueous ammonia was added to neutralize the mixture to a pH of 7.5 to yield a copolymer emulsion having a glass transition temperature of 105~C and a solid content of 39%, Example 2 A copolymer emulsion having a glass transition temperature of 105C and a solid content of 39% was prepared in the same manner as in Example 1 except that the emulsifier used was 13 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide ~10 mol of ~0 was added) adduct sulfate as a reactive emulsifier.
Example 3 To a reactor, 400 parts of water, 20 parts of sodium dodecylbenzenesulfonate, 37,5 parts of methacrylic acid, 18 parts of methyl methacrylate, 28.5 2 ~ 7 parts of n butyl acrylate, 14 parts of s~yrens and 1 part of n-dodecylmercaptane were added, and they were mixed therein, Then, 1 part of a 20~ aqueou~ ~olution of ammonium persulfate was added, and the mixture was kept at 85O~ fox 5 hours, after which it was cooled to 50OC and neutralized by the gradual addition of 69.8 parts of a 20% aqueous solution of sodium hydroxideO
Then, water was added to adjust ~he solid content to 20% to yield a high molecular emulsifier having a molecular weight of 210~0.
A copolymer emulsion having a glass transition temperature of lOSC and a solid contenk of 39% was prepared in the same manner as in Example 1 except that the amount of water added was 248 parts and 65 parts of the high molecular emulsifier described above was used.
Exampl~ 4 To a reactor, 310 parts o water, 6 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide (10 mol of EO was added) adduct sulfate as a reac~ive emulsifier, 36 parts o styxene, 30 parts of methyl methacrylate, 10.4 parts of ethyl methacrylate, 2 parts of divinylbenzene and 1.6 parts of methacrylic acid were charged. The temperature was increased ~o 70C
while replacing the inside atmosphere with nitrogen.
After adding 5 parts of a 16% aqueous solu~ion of 2~A ~7 potassium persulfate, the mixture was kept at 85OC for 4 hours ~or polymerization.
After completing of the reaction, aqueous ammonia - was added to neutralize the mixture to a pH of 7.5 to yield a copolymer emulsion having a glass transition temperature o 98C and a solid content of 21%.
Example 5 A copolymer emulsion having a glass transition temperature of 103C and a solid content o-E 39% was prepared in the same manner as in Example 2 except that the monomer components used were 176 parts of styrene, 14 parts of a methylstyrene and lO parts of methacrylic acid.
Example 6 A copolymer emulsion having a glass transition temperature of 98C and a solid content of 21% was prepared in the same manner as in Example 4 except tha~
the monomer components used were 66 parts of methyl methacrylate, 12 parts o ethyl mekhacrylate and 2 parts of acrylic acid.
Comparative Example 1 A copolymer emulsion having a glass transition temperature of 69C and a solid content of 39% was 2 9 ~
prepared in the same manner as in ~ample 3 except tha~
the monomer components used were 45 parts of styrene, 19 parts of methyl methacrylate, 34 parts of n~butyl methacrylate and 2 parts of acrylic acid.
Comparative Example 2 A copolymer emulsion having a glass transition temperature of 88C and a solid content of 3g% was prepared in the same manner as in ~xample 1 except that the monomer components used were 40 parts of styrene, 16 parts of methyl methacrylate, 40 parts of isobutyl methacrylate and 4 parts o methacrylic acid.
Comparative ~xample 3 To a reactor, 302 parts of water, 6 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide (10 mol of EO was added) adduct sulfa~e as a reactive emulsifier, and 40 par~s of styrene, 24 paxts of methy~
methacrylate, 4 parts o ethyl methacrylate, 6.4 parts of methacrylic acid and 14 parts of 40~ acrylamide as monomer components were charged. The temperature was increased to 70C while replacing the inside atmosphere with nitrogen. After adding 5 parts of a 16% aqueous solution of potassium persulfate, the mixture was kept at 85C for 4 hours for polymerization, After completing the reaction, aqueous ammonia was added to neutralize the mix~ure ~o a p~ o~ 7 . 5 ~o yield a copolymer emulsion having a glass kransition tempera-ture of 105C and a solid content o~ 20~.
The compositions o the copolymer emulsions obtained in Examples and Comparative Example~ are shown in Table 1 J in which the symbols A, B, C and D in the column for emulsifiers respectively represent the following emulsifiers.
A: Ammonium polyoxyethylene (n = 10) nonylphenol ether sulfate B: Disodium nonyldiphenyl ether disulfonate C: Ammonium salt of allylnonylphenol polyethylene oxide (10 mol of EO was added) adduct sulfate, a reactive emulsifier D: High molecular emulsifier synthesized in Example 3 2 ~ ~ ~ 2 ~ ~
Table 1. Compositions of copolymer emulsions _ Ccmparative Examples ~xamples _ 2 _ _ _ _ _ _ _ _ Emulsifier A C D C D C D A C
Styrene 50 50 50 4S 88 45 4050 Methyl 38 38 38 37.5 82.5 19 1630 methacrylate _ _ Ethyl 13 15 5 mon- methacrylate _ _ omer ~-methylstyrene 7 7 7 7 mix- n-~utyl 34 methacrylate ture Isobutyl 40 comr methacryla~e __ __ __ po- Divinylbenzene 2.5 _ _ nents Methacrylic acid 5 5 5 2 5 _ 4 8 Acrylic acid _ 2.S 2 Acrylamide 7 _~ _ __ Glass transition 105 105 105 98 103 98 69 88 105 temperature (oC) _ ~
-- 2 Q ~ 7 Next, a paper suracs trea~ment tes~ was conducted using paper surface treating agents whose active ingredient is one of the copolymer emulsions obtained in Examples and Compara~ive Examples. The test was performed as dir~cted below. The results are given in Table 2, which clearly demonstrate that the paper surface treating agent according to the present inven-tion provides a high gloss to paper and offers improved printability for paper.
(1) Preparation of base paper On a stock sheet of wood~free paper having an areal weight of 100 g/m2, a coating solution having a solid content of 50~ comprising 80 parts of kaolin, 20 parts of light calcium carbonate, 13 parts (as solid content ) of styrene-butadiene ru~ber latex and 7 parts (as solid content) of phosphate-modi~ied starch was coated so that the dry solid content became 15 g/m2 on one face and dried to yield an u~der coated base paper.
(2) C~ating To each copolymer emulsion obtained in Examples and Compara~ive Examples, a wax emulsion based mold release agent was added ln a solid ~ontent ratio of 5%, and this mixture was diluted with water to yield a coating solution having a solid 2~2~7 content of 20%.
Each coating solution ob~ained in the above manner was coa~ed on the base coated paper prepared in (1) above using a rod coater so that the solid content became 1.0 g/m2. Af~er drying, calendering was performed two cycles using a super-calenderer equipped with alterna-tively arranged metal rolls and filled rolls at a linear pressure of 130 kg/cm and a roll tem-perature of 60C. With respect to the coating solution prepared with ~he copolymer emulsion obtained in Example 2, a sample not subjecked to super-calendering was also tested.
PAPER S~RFACE~ TREATING AG:13NT
II. BACKGRO[~ND OF THE INVENTION
The present invention relakes to a paper surface trea~ing agent which provide~ a high gloss for the surface of printing paper and which offers a good ink adherence upon printing, ~ enerally, glossy paper is made by forming a coat on the surface of paper with a dispersion of pigment in a binder such as a water-soluble or waker-dispersible high molecular polymer latex and subseguently subject-ing the paper to calendering, Anothex method of glossy paper making is to coat paper with resin. Speciflcally, a resin coat film is formed on the surface of paper by coating a molten solution of resin or a water-soluble or water-dispersible resin, III . SUMMARY OF THE INVENTION
However, the ~ormer me~hod, in which paper is coated with a dispersed pigment in binder and calen-dered, does not always ofer a satisfactory gloss, requiring specially designed equipmenk such as a cast coater to obtain higher glossO
As for the latter method, in which paper is coated with resin, it has a disadvantage that the obtained coated paper is unsuitable for use as printing paper because of poor ink absorption and slow ink drying in the printing process~ though a high gloss is obtained.
The present invention was developed to solve these problems. It ~rovides a paper surface treating agent which provides an excellent gloss for the surface of paper and which offers a good surface condition with high printability for printing paper.
Accordingly, the paper surface treating agent of the present invention is characterized in that its active ingredient is a copolymer emulsion prepared by emulsification polymerization of a monomer composition of 70 to 99 w~ styrene and/or methyl methacrylate, 1 to 10 wt% water-soluble monomer and not more than 29 wt% of other copolymerizable oil-soluble monomers (figures for percent r~tio are relative to the total amount o the monomers subjected to emulsification polymerization) in the presence of an anionic emul~
sifier wherein the copolymer in said copolymer emulsion has a glass transition temperature of over 80~C.
The monomer composition which constitutes the copolymer of the present invention incorporates styrene and/or methyl methacrylate as the major component. In the present invention, styrene and methyl methacryIate are equivalent to each other; they may be used singly or in combination. lt is preerable, however, that ~he weight ratio of styrene and methyl methacrylate be 7:3 to 3:7 from the viewpoint of preventing roll staining upon heat roll treatment and adjusting ink set in offset printing.
The ratio of styrene and/or methyl methacrylate in the monomer composition, i.e., in the copolymer is preferably 70 to 99 wt%, more preferably 85 to 99 wt%.
If the ratio is below this range, the glass transition temperature of the copolymer decreases, and even if the glass transition temperature an be increased, then the printability is degraded because blocking occurs upon calendering after coating and because emulsion grains show excess aggre~ation in a molten state to form a tight film-like coat.
Examples of water-soluble monomers which can be used to compose the copolymer of the present invention include mono or dicarboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid, hydroxy compounds such as hydroxyethyl methacrylate, hydroxypropyl meth-acrylate, hydroxyethyl acrylate and hydroxypropyl acrylate, methacrylamide, acrylamide and sty renesulfonate. These water-soluble monomers may be used singly or in combination.
The ratio of the water-soluble monomers used should he 1 to 10 wt%. The ratio should be over 1 wt%
Eor the stabilization of the copolymer emulsion, but if it exceeds 10 wt%, ink setting upon printing is degraded because exaess emulsion grains aggrega~ion in a molten state occurs during drying as the surface of the emulsion grains becomes water-soluble and the outer portion o~ the emulsion grains becomes more water-soluble.
In addition to the styrenetand or methyl methacrylate and water-soluble monomers described above, a copolymerizable oil-soluble monomer can be added as a monomer composition at not more than 29 wt~
to constitute the copolymer of the present invention if necessary. Although the Xind of the copolymerizable oil-soluble monomer is not subject to limitation, a monomer showing a glass transition temperature of over 40OC when it is prepared as a homopolymer is preferred.
Bxamples of suitable monomers include ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, a-methyl styrene, vinyl toluene, acrylonitrile, methacrylonitrile and crosslinkable monomers such as glycidyl methacrylate and divinylbenzene.
The copolymer of the present invention is prepared by emulsification polymerization of the monomer compo-sition described above in the presence of an anionic 2 3 ''JL ~1 'J1 ~ P
emulsiier, The anionic emulsifier for emulsification polymerization o the monomer composition is one or more anionic emulsifiers selected from the group comprising ordinary anionic emulsifiers, anionic reactive emulsifiers and anionic high molecular emulsifiers, Examples of the ordinary anionic emulsifier used here include higher alcohol sulfates, alkylbenzen-esulfonates, aliphatic sulfonates, dialkylsulfo-succinates, alkylnaphthalenesulfonates, alkyldiphenyl ether disulfonates, polyoxyethylene alkyl ether sulfates and polyoxyethylene alkylphenol ether sulfates~
lS Examples of ~h~ anionic reactive emulsifier include reactive emulsifiers containing a phosphats group prepared by the addition of 8 mol on avexage of ethylene oxide to acrylic acid in accordance with a conventional method followed by reaction with phosphoric anhydride; ammonium salt of allylnonylphenol polyethylene oxide ~10 mol) adduct sulate, acrylic acid or methacrylic acid derivatives and reactive emulsifiers containin~ an allyl group, Examples of the high molecular emulsifier include 2S ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid~ itaconic acid, maleic acid and fumaric acid, and homopolymer salts of a monomer containing a sulonic acid group, such as styrenesulfonic acid and 2-acrylamide-2-methyl-propanesulfonic acid and allylalkylsulfosuccinic acid.
It is also possible to u~e copolymers of an ethyl enically unsaturated carboxylic acid monomer described above or its salt or a monomer containing a sulfonic acid group described above or its salt and an aromatic unsaturated monomer such as styrene, ~-methylstyrene or vinyltoluene or an alkyl ester of acrylic acid or methacrylic acid such as ethyl ~meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or dodecyl (meth)acrylate, The average molecular weight of these high molecular emulsifiers is preferably about 2000 to 1 100000.
The copolymer of the present invention should have a glass transition temperature of over 80C. I the glass transi.tion temperature is below 80C, blocking or roll staining ocaurs upon hot calendering after coating, and the absorbability and dryability of print-ing ink are degraded because the emulsion grains aggregate in a molten state to form a coat upon hot pressurization.
The paper surface treating agent of the present invention can be prepared by a conventional method such as the method in which water, the emulsifier described ~3 ~ rl abov~ and star~ing monomers axe mi~ed and then polymerized with heating in the presence of a polymerization initiator such as a persulfate, peroxy compound or azobis compound, and the method in which S polymerization is carried out in the presence of a redox catalyst such as a combination of a persulfate or peroxide and iron salt, ascorbic acid, sulfite or the like. It is unnecessary to add an inorganic pigment to the copolymer component during preparation.
The paper surface treating agent of the present invention can be coated on uncoated paper such as wood-free paper or moderate quality paper or coated paper, particularly on coat paper and on coated paper undercoated with a small amount of an aqueous resin such as polyvinyl alcohol, polyacrylamide or anokher water-soluble resin for the purpose of filling by various coating methods.
The coating composi~ion may contain according ~o the necessity a mold release agent, a water-soluble resin such as casein or starch, a colorant and other additives in small amounts, as long as the gloss is not degraded.
After coating, the paper is dried under ordinary conditions for coat paper making, ater which it is subjected to super calendering or gloss calendering, which offers a high gloss, a~ temperatures below 80C, r~ rl whereby highly printable qlossy paper which has a high gloss and which does not cause roll staining or blocking is obtained.
The paper surface treating agen~ of the present invention, unlike the prior art surface treating agents for glossy paper, is not accompanied by film-like coating of grains by complete aggregation in a molten state because its glass transition temperature is as hiyh as over 80C. In addition, calendering after coating and drying yields a coat of partially aggre-gated emulsion grains, resulting in the formation of a coat having fine pores.
Thereore, fine hard grains form a smooth coat on the surface of coated paper to give a high gloss, and blocking is not liable to occur. Furthermore, ink absorbability upon printing is good because a large number of fine pores are present on the surface of the coat. With these favorable features, excellent printability is obtained unlike the conventional glossy paper.
It is evident that the paper surface treating agent o the present invention, which comprises a copolymer emulsion, when used to improve the paper surface properties, offers high levels of white paper ~5 gloss, printing gloss and excellent ink set which are discrived after. Also, the paper subjected to surface f.,~l ~
treatment wlth the paper surface treating agent of the present invention, even when not subjec~ed to calendering, is capable of having a level of whit~
gloss nearly equal to that commercially available 5 calendered coat paper.
IV. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
~ he present invention is hereinafter described in more detail by means of the following esamples. In the description below, "part(s)" and "%" mean "part~s~ by weight" and "wt~", respectively.
Examples 1 To a reactor equlpped with a stirrer, a dripping tank and a thermometer, 300 g of water and emulsifiers, specifically 9 parts of ammonium polyo~yethylene ~n =
10) nonylphenol ether sulfate and 4 parts of disodium nonyldiphenyl ether disulfonate, were charged, and they were mixed therein.
To this mixture, 60 parts of a monomer mixture prepared by mixing 100 par~s of styrene, 10 parts of ~-methylstyrene, 76 parts of methyl methacrylate and 10parts of methacrylic acid was added, and the tempera-ture was increased to 60C while replacing the inside atmosphere with nitrogenO While keeping this tempera-ture, 7.2 parts of a 20% aqueous solution of ammonium 2 ~ 7 persulfate and 4.8 parts of a 20% aqueous solution of anhydrous sodium bisulfite were added as a redo~
catalyst, followed by polymerization ~or 1 hour.
After adding 10 parts of a 20~ aqueous solution of ammonium persulfate, the remaining 140 parts of the monomer mixture described above was added dropwise over a period of L hour. Then, the temperature was increased to 90C, and reaction ended after keeping the temperature at 900C for 4 hours~
After completing o the reaction, aqueous ammonia was added to neutralize the mixture to a pH of 7.5 to yield a copolymer emulsion having a glass transition temperature of 105~C and a solid content of 39%, Example 2 A copolymer emulsion having a glass transition temperature of 105C and a solid content of 39% was prepared in the same manner as in Example 1 except that the emulsifier used was 13 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide ~10 mol of ~0 was added) adduct sulfate as a reactive emulsifier.
Example 3 To a reactor, 400 parts of water, 20 parts of sodium dodecylbenzenesulfonate, 37,5 parts of methacrylic acid, 18 parts of methyl methacrylate, 28.5 2 ~ 7 parts of n butyl acrylate, 14 parts of s~yrens and 1 part of n-dodecylmercaptane were added, and they were mixed therein, Then, 1 part of a 20~ aqueou~ ~olution of ammonium persulfate was added, and the mixture was kept at 85O~ fox 5 hours, after which it was cooled to 50OC and neutralized by the gradual addition of 69.8 parts of a 20% aqueous solution of sodium hydroxideO
Then, water was added to adjust ~he solid content to 20% to yield a high molecular emulsifier having a molecular weight of 210~0.
A copolymer emulsion having a glass transition temperature of lOSC and a solid contenk of 39% was prepared in the same manner as in Example 1 except that the amount of water added was 248 parts and 65 parts of the high molecular emulsifier described above was used.
Exampl~ 4 To a reactor, 310 parts o water, 6 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide (10 mol of EO was added) adduct sulfate as a reac~ive emulsifier, 36 parts o styxene, 30 parts of methyl methacrylate, 10.4 parts of ethyl methacrylate, 2 parts of divinylbenzene and 1.6 parts of methacrylic acid were charged. The temperature was increased ~o 70C
while replacing the inside atmosphere with nitrogen.
After adding 5 parts of a 16% aqueous solu~ion of 2~A ~7 potassium persulfate, the mixture was kept at 85OC for 4 hours ~or polymerization.
After completing of the reaction, aqueous ammonia - was added to neutralize the mixture to a pH of 7.5 to yield a copolymer emulsion having a glass transition temperature o 98C and a solid content of 21%.
Example 5 A copolymer emulsion having a glass transition temperature of 103C and a solid content o-E 39% was prepared in the same manner as in Example 2 except that the monomer components used were 176 parts of styrene, 14 parts of a methylstyrene and lO parts of methacrylic acid.
Example 6 A copolymer emulsion having a glass transition temperature of 98C and a solid content of 21% was prepared in the same manner as in Example 4 except tha~
the monomer components used were 66 parts of methyl methacrylate, 12 parts o ethyl mekhacrylate and 2 parts of acrylic acid.
Comparative Example 1 A copolymer emulsion having a glass transition temperature of 69C and a solid content of 39% was 2 9 ~
prepared in the same manner as in ~ample 3 except tha~
the monomer components used were 45 parts of styrene, 19 parts of methyl methacrylate, 34 parts of n~butyl methacrylate and 2 parts of acrylic acid.
Comparative Example 2 A copolymer emulsion having a glass transition temperature of 88C and a solid content of 3g% was prepared in the same manner as in ~xample 1 except that the monomer components used were 40 parts of styrene, 16 parts of methyl methacrylate, 40 parts of isobutyl methacrylate and 4 parts o methacrylic acid.
Comparative ~xample 3 To a reactor, 302 parts of water, 6 parts of ammonium salt of allylnonylphenol polyoxyethylene oxide (10 mol of EO was added) adduct sulfa~e as a reactive emulsifier, and 40 par~s of styrene, 24 paxts of methy~
methacrylate, 4 parts o ethyl methacrylate, 6.4 parts of methacrylic acid and 14 parts of 40~ acrylamide as monomer components were charged. The temperature was increased to 70C while replacing the inside atmosphere with nitrogen. After adding 5 parts of a 16% aqueous solution of potassium persulfate, the mixture was kept at 85C for 4 hours for polymerization, After completing the reaction, aqueous ammonia was added to neutralize the mix~ure ~o a p~ o~ 7 . 5 ~o yield a copolymer emulsion having a glass kransition tempera-ture of 105C and a solid content o~ 20~.
The compositions o the copolymer emulsions obtained in Examples and Comparative Example~ are shown in Table 1 J in which the symbols A, B, C and D in the column for emulsifiers respectively represent the following emulsifiers.
A: Ammonium polyoxyethylene (n = 10) nonylphenol ether sulfate B: Disodium nonyldiphenyl ether disulfonate C: Ammonium salt of allylnonylphenol polyethylene oxide (10 mol of EO was added) adduct sulfate, a reactive emulsifier D: High molecular emulsifier synthesized in Example 3 2 ~ ~ ~ 2 ~ ~
Table 1. Compositions of copolymer emulsions _ Ccmparative Examples ~xamples _ 2 _ _ _ _ _ _ _ _ Emulsifier A C D C D C D A C
Styrene 50 50 50 4S 88 45 4050 Methyl 38 38 38 37.5 82.5 19 1630 methacrylate _ _ Ethyl 13 15 5 mon- methacrylate _ _ omer ~-methylstyrene 7 7 7 7 mix- n-~utyl 34 methacrylate ture Isobutyl 40 comr methacryla~e __ __ __ po- Divinylbenzene 2.5 _ _ nents Methacrylic acid 5 5 5 2 5 _ 4 8 Acrylic acid _ 2.S 2 Acrylamide 7 _~ _ __ Glass transition 105 105 105 98 103 98 69 88 105 temperature (oC) _ ~
-- 2 Q ~ 7 Next, a paper suracs trea~ment tes~ was conducted using paper surface treating agents whose active ingredient is one of the copolymer emulsions obtained in Examples and Compara~ive Examples. The test was performed as dir~cted below. The results are given in Table 2, which clearly demonstrate that the paper surface treating agent according to the present inven-tion provides a high gloss to paper and offers improved printability for paper.
(1) Preparation of base paper On a stock sheet of wood~free paper having an areal weight of 100 g/m2, a coating solution having a solid content of 50~ comprising 80 parts of kaolin, 20 parts of light calcium carbonate, 13 parts (as solid content ) of styrene-butadiene ru~ber latex and 7 parts (as solid content) of phosphate-modi~ied starch was coated so that the dry solid content became 15 g/m2 on one face and dried to yield an u~der coated base paper.
(2) C~ating To each copolymer emulsion obtained in Examples and Compara~ive Examples, a wax emulsion based mold release agent was added ln a solid ~ontent ratio of 5%, and this mixture was diluted with water to yield a coating solution having a solid 2~2~7 content of 20%.
Each coating solution ob~ained in the above manner was coa~ed on the base coated paper prepared in (1) above using a rod coater so that the solid content became 1.0 g/m2. Af~er drying, calendering was performed two cycles using a super-calenderer equipped with alterna-tively arranged metal rolls and filled rolls at a linear pressure of 130 kg/cm and a roll tem-perature of 60C. With respect to the coating solution prepared with ~he copolymer emulsion obtained in Example 2, a sample not subjecked to super-calendering was also tested.
(3) Testing items White paper gloss: Determined in accordance with JIS P-8142 (75 reflection method).
Printing gloss: Determined in accordance with JIS P-8142 (75~ reflection method) 1 day after ofset ink printing using an RI printing tester.
Ink set: After ofset ink printing using an RI
printing tester, a stock sheet of coat paper was immediately superposed on the printed face and pressed onto a rubber roll, a~ter which the degree of ink trans~er to the stock sh0et of coat paper was evaluated, The evaluation cxiteria were: good setting ( O), slightly 510w 2~13~J~3 setting ( ~) and slow setting ( ~ ).
2 ~
Table 2. Results of the paper surface treatment test Calendering White P ti Treat mg paper r m ng Ink set agent Yes/No Roll staining gloss (~) gloss (l) Example 1 Yes (-~ 76 78 O
Example 2 Yes (-) 81 86 O
Example 3 Yes (-) 80 84 O
Example 4 Yes(-) ~ (+) 33 88 O ~
Ex~nple 5 Yes(-) ~ (+) 82 89 o ~
Example 6 Yes (-) 77 78 O
Example 2 No _ SB 76 O
Comparative Yes(+~ 73 87 ~ _ xample 1 = e 2 Yes (+) ~(+) 68 74 ~ X
Ckmparative Yes(-) 72 83 coTmercially available 60 87 O
coat paper _ -- 1~ -
Printing gloss: Determined in accordance with JIS P-8142 (75~ reflection method) 1 day after ofset ink printing using an RI printing tester.
Ink set: After ofset ink printing using an RI
printing tester, a stock sheet of coat paper was immediately superposed on the printed face and pressed onto a rubber roll, a~ter which the degree of ink trans~er to the stock sh0et of coat paper was evaluated, The evaluation cxiteria were: good setting ( O), slightly 510w 2~13~J~3 setting ( ~) and slow setting ( ~ ).
2 ~
Table 2. Results of the paper surface treatment test Calendering White P ti Treat mg paper r m ng Ink set agent Yes/No Roll staining gloss (~) gloss (l) Example 1 Yes (-~ 76 78 O
Example 2 Yes (-) 81 86 O
Example 3 Yes (-) 80 84 O
Example 4 Yes(-) ~ (+) 33 88 O ~
Ex~nple 5 Yes(-) ~ (+) 82 89 o ~
Example 6 Yes (-) 77 78 O
Example 2 No _ SB 76 O
Comparative Yes(+~ 73 87 ~ _ xample 1 = e 2 Yes (+) ~(+) 68 74 ~ X
Ckmparative Yes(-) 72 83 coTmercially available 60 87 O
coat paper _ -- 1~ -
Claims (6)
1. A paper surface treating agent characterized in that its active ingredient is a copolymer emulsion prepared by emulsification polymerization of a monomer composition of 70 to 99 wt% styrene and/or methyl methacrylate, 1 to 10 wt% water-soluble monomer and not more than 29 wt% of other copolymer-izable oil-soluble monomers (figures for percent ratio are relative to the total amount of the monomers subjected to emulsification polymerization) in the presence of an anionic emulsifier wherein the copolymer in said copolymer emulsion has a glass transition temperature of over 80°C.
2. The paper surface treating agent of claim 1 wherein said major component of the monomer composi-tion subjected to emulsification polymerization in the presence of an anionic emulsifier is at least one of styrene and methyl methacrylate.
3. The paper surface treating agent of claim 2 wherein styrene and methyl methacrylate are used in a weight ratio of 7:3 to 3:7 when they are used in combination as the major components of the monomer composition subjected to emulsification polymeri-zation along with other monomers in the presence of an anionic emulsifier.
4. The paper surface treating agent of claim 1 wherein said water-soluble monomer subjected to emulsification polymerization along with other monomers in the presence of an anionic emulsifier is one or more substances selected from the group comprising mono- or dicarboxylic acids, hydroxy compounds, amides, salts and other water-soluble organic compounds.
5. The paper surface treating agent of claim 1 wherein said copolymerizable oil-soluble monomer used shows a glass transition temperature of over 40°C
when it is prepared as a homopolymer.
when it is prepared as a homopolymer.
6, The paper surface treating agent of claim 1 wherein said anionic emulsifier which emulsifies and polymerizes the monomer composition is one or more emulsifiers selected from the group comprising ordinary anionic emulsifiers, anionic reactive emulsifiers and anionic high molecular emulsifiers.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3-57837 | 1991-02-27 | ||
| JP03057837A JP3104076B2 (en) | 1991-02-28 | 1991-02-28 | sewing machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2045207A1 true CA2045207A1 (en) | 1992-08-28 |
Family
ID=13067072
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2045207 Abandoned CA2045207A1 (en) | 1991-02-27 | 1991-06-21 | Paper surface treating agent |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3104076B2 (en) |
| CA (1) | CA2045207A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0730684B1 (en) * | 1993-11-23 | 2002-02-06 | Wilcom Tufting Pty. Ltd. | A mechanical tufting head |
| JP3646067B2 (en) * | 2001-01-26 | 2005-05-11 | ペガサスミシン製造株式会社 | Sewing machine needle bar stroke changing device |
| CN110983662B (en) * | 2019-12-23 | 2021-10-29 | 拓卡奔马机电科技有限公司 | Cloth-needling mechanism and sewing equipment with same |
-
1991
- 1991-02-28 JP JP03057837A patent/JP3104076B2/en not_active Expired - Fee Related
- 1991-06-21 CA CA 2045207 patent/CA2045207A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04272265A (en) | 1992-09-29 |
| JP3104076B2 (en) | 2000-10-30 |
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