JP4470477B2 - Polymer latex for oil-resistant paper and oil-resistant paper - Google Patents

Description

  The present invention relates to a polymer latex for oil-resistant paper, a process for producing the same, a coating composition for oil-resistant paper, and oil-resistant paper. More specifically, the present invention can be suitably used for food packaging, has very little odor, oil resistance, and blocking resistance. The present invention relates to a polymer latex for oil-resistant paper that gives oil-resistant paper having excellent properties and disaggregation, a method for producing the latex, a coating composition for oil-resistant paper containing the polymer latex for oil-resistant paper as a main component, and oil-resistant paper using the same.

Oil-resistant paper is a paper having a function of suppressing or preventing permeation of fats and oils, and is widely used as a sheet or package that comes into contact with foods containing fats and oils such as chocolate, snacks, and fried chicken.
As a method of imparting oil resistance to paper, there is a method of laminating an oil resistant synthetic resin film on the paper surface. However, such oil-resistant paper has the disadvantage that when it is to be recycled after using the oil-resistant paper, it has no disaggregation property and is difficult to recover as a recycled material.
Accordingly, there is a demand for oil-resistant paper that can be recovered as waste paper, disassembled and reused.

  For example, an oil-resistant paper coated with an acrylic emulsion having a glass transition temperature of 10 to 28 ° C. has been proposed (see Patent Document 1). However, this oil-resistant paper is still insufficient in oil resistance, and is not satisfactory in terms of blocking resistance under relatively high temperature conditions such as immediately after being applied to a base paper and dried.

  In addition, an oil-resistant paper coated with a core-shell type acrylic emulsion composed of a core part having a glass transition temperature of -20 to 25 ° C. and a shell part having a glass transition temperature of 90 to 140 ° C. has been proposed (see Patent Document 2). . However, this oil-resistant paper is relatively excellent in blocking resistance but has insufficient disaggregation and oil resistance.

  Furthermore, an oil-resistant paper is proposed in which a base paper is coated with a paint obtained by blending 50 to 200 parts by weight of a mixture of an acrylic emulsion and a styrene-butadiene emulsion with respect to 100 parts by weight of a pigment (see Patent Document 3). ). However, this oil-resistant paper has excellent oil resistance and is relatively easy to disaggregate, but has insufficient blocking resistance.

On the other hand, when oil-resistant paper is used for food packaging, the odor of the oil-resistant paper may be transferred to the contents, which may significantly reduce the commercial value of the contents. Therefore, there is a need for an oil-resistant paper having an extremely low odor suitable for food packaging.
However, the conventional oil-resistant paper described above sometimes has a problem in terms of odor.

JP-A-9-111893 JP 2001-303475 A JP 2002-13095 A

  In view of the above circumstances, the object of the present invention is to provide an oil-resistant paper polymer latex that provides oil-resistant paper that has extremely low odor, excellent oil resistance and blocking resistance, and is easy to disaggregate, and the oil-resistant paper polymer latex as a main component. An object of the present invention is to provide a coating composition for oil-resistant paper and an oil-resistant paper using the same.

  As a result of intensive studies to achieve this object, the present inventors have found that a specific polymer obtained by polymerizing a monomer in the presence of a water-soluble polymer compound containing an alcoholic hydroxyl group in an aqueous medium. It has been found that the object can be achieved by a polymer latex containing a glass transition temperature polymer and having an odor intensity of a certain value or less, and the present invention has been completed based on this finding.

Thus, according to the present invention , a conjugated diene monomer, an aromatic vinyl monomer, an ethylenically unsaturated nitrile monomer in the presence of a vinyl alcohol polymer in an aqueous medium, without using a surfactant. And a monomer mixture comprising at least one selected from ethylenically unsaturated carboxylic acid alkyl ester monomers and 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomers in the total amount of monomers A polymer having a glass transition temperature of −10 to 45 ° C. obtained by polymerizing a polymer and having a vinyl alcohol polymer bonded to the polymer derived from the monomer mixture in an amount of 1 to 15% by weight based on the total amount. comprising a polymer latex for oil feeding, the solid content of 30% by weight of the polymer latex, oil paper for polymer latex odor intensity was measured in accordance with JIS K 0101 is 100,000 or less It is provided.
Further, according to the present invention, previously for Kikasane 100 parts by weight of the solid content of the polymer latex, blowing 50 to 150 parts by weight of water vapor in the polymer latex, the method of producing the polymer latex for oil paper for steam distillation Is provided.
Furthermore, according to this invention, the coating composition for oil-resistant paper which contains the said polymer latex for oil-resistant paper as a main component is provided.
Furthermore, according to the present invention, there is provided an oil-resistant paper obtained by coating the above-mentioned oil-resistant paper coating composition on a base paper.

  According to the present invention, a polymer latex for oil-resistant paper that can be suitably used for food packaging, gives an oil-resistant paper that has an extremely low odor, and is excellent in oil resistance, blocking resistance, and disaggregation, a method for producing the same, and a method for producing the oil-resistant paper Provided are an oil-resistant paper composition containing a combined latex as a main component and an oil-resistant paper using the same.

Hereinafter, the present invention will be described in detail.
The polymer latex for oil-resistant paper of the present invention is a polymer latex having a glass transition temperature of −20 to 50 ° C. obtained by polymerizing monomers in the presence of a water-soluble polymer compound containing an alcoholic hydroxyl group in an aqueous medium. It is a polymer latex for oil-resistant paper containing a coalescence, and the odor strength measured according to JIS K 0101 is about 200,000 or less for the polymer latex having a solid content concentration of 30% by weight.

  The polymer latex for oil-resistant paper of the present invention is a polymer latex having a glass transition temperature of −20 to 50 ° C. obtained by polymerizing monomers in the presence of a water-soluble polymer compound containing an alcoholic hydroxyl group in an aqueous medium. Includes coalescence.

  The monomer is not particularly limited as long as it can be radically polymerized, and examples thereof include conjugated diene monomers, aromatic vinyl monomers, ethylenically unsaturated nitrile monomers, and ethylenically unsaturated carboxylic acid monomers. A monomer, an ethylenically unsaturated carboxylic acid alkyl ester monomer, and an ethylenically unsaturated carboxylic acid amide monomer.

  Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 2-chloro. Examples include -1,3-butadiene and 1,3-pentadiene. Of these, 1,3-butadiene can be preferably used.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, trichlorostyrene, methylstyrene, dimethylstyrene, trimethylstyrene, and hydroxymethylstyrene. Of these, styrene can be preferably used.

  Examples of the ethylenically unsaturated nitrile monomer include acrylonitrile, methacrylonitrile, 2-chloropropenenitrile, 2-butenenitrile and the like. Of these, (meth) acrylonitrile can be preferably used.

  Examples of the ethylenically unsaturated carboxylic acid monomer include ethylenically unsaturated monocarboxylic acid monomers such as acrylic acid, methacrylic acid, and crotonic acid; fumaric acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride Ethylenically unsaturated polyvalent carboxylic acid monomers and anhydrides thereof such as; partially esterified products of ethylenically unsaturated polyvalent carboxylic acid monomers such as monoethyl fumarate, monomethyl maleate and monomethyl itaconate; It is done.

  Examples of ethylenically unsaturated carboxylic acid alkyl ester monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylic acid. Examples include 2-hydroxyethyl, dimethyl fumarate, diethyl maleate, diisopropyl itaconate and the like.

  Examples of the ethylenically unsaturated carboxylic acid amide monomer include (meth) acrylamide, N, N-dimethylacrylamide, N-methylolacrylamide and the like.

  Besides these monomers, for example, carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl versatate; monoolefin monomers such as ethylene, propylene, 1-butene and isobutene; methyl vinyl ether, Vinyl ether monomers such as n-propyl vinyl ether, isobutyl vinyl ether and dodecyl vinyl ether; vinyl trimethoxysilane, vinyl pyridine, N-vinyl pyrrolidone and the like can be used.

One or more of the above monomers can be selected and used.
Among the above monomers, conjugated diene monomer, aromatic vinyl monomer, ethylenically unsaturated nitrile monomer, ethylenically unsaturated carboxylic acid monomer and ethylenically unsaturated carboxylic acid alkyl ester The body can be preferably used.
In view of excellent mechanical stability and blending stability of the obtained polymer latex, it is preferable to use an ethylenically unsaturated carboxylic acid monomer, and the amount used is a monomer used in polymerization. More preferably, it is in the range of 0.5 to 10% by weight based on the total amount.

As the aqueous medium used in the present invention, water can be usually used, and an aqueous solution containing an alcohol such as methanol and ethanol; and an aqueous organic solvent such as acetone and tetrahydrofuran can also be used.
The amount of the aqueous medium used is preferably 90 to 900 parts by weight, more preferably 100 to 500 parts by weight with respect to 100 parts by weight of the monomer used for the polymerization.

  Examples of the water-soluble polymer compound containing an alcoholic hydroxyl group used in the present invention (hereinafter sometimes abbreviated as “alcoholic hydroxyl group-containing water-soluble polymer compound”) include polyvinyl alcohol and various modified products thereof. Vinyl alcohol polymers of: cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, alkyl hydroxyalkyl cellulose, carboxymethyl cellulose; starch derivatives such as alkyl starch, carboxymethyl starch, oxidized starch; gum arabic, tragacanth rubber, polyalkylene glycol, etc. Can be mentioned. Among these, a vinyl alcohol polymer can be preferably used because it is easy to obtain an industrially stable product.

  The vinyl alcohol polymer is not particularly limited as long as it is a substantially water-soluble and stable latex can be obtained, and an ethylenic polymer mainly composed of a carboxylic acid vinyl ester monomer. Carboxylic acid vinyl ester polymer obtained by polymerizing a saturated monomer by a conventionally known method (that is, a homopolymer of a carboxylic acid vinyl ester monomer and a copolymer of two or more carboxylic acid vinyl ester monomers) And saponified by a conventional method), and a copolymer of a carboxylic acid vinyl ester monomer and another ethylenically unsaturated monomer copolymerizable therewith. Moreover, what introduce | transduced modifying groups, such as a mercapto group, into the principal chain, side chain, or terminal of a molecule | numerator can also be used.

  As the carboxylic acid vinyl ester monomer, any monomer capable of radical polymerization can be used, and specific examples thereof include vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl valerate, capric acid. Examples thereof include vinyl, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate, and vinyl pivalate. Of these, industrially produced and inexpensive vinyl acetate is common.

  It is also possible to co-polymerize one or more ethylenically unsaturated monomers copolymerizable with a carboxylic acid vinyl ester monomer. Examples of these copolymerizable ethylenically unsaturated monomers include, for example, monoolefin monomers such as ethylene, propylene, 1-butene and isobutene; acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid and fumaric acid. Ethylenically unsaturated carboxylic acid monomers such as monoethyl acid, maleic anhydride, phthalic anhydride, trimetic anhydride, itaconic anhydride; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid n -Ethylenically unsaturated carboxylic acid alkyl ester monomers such as butyl, 2-ethylhexyl (meth) acrylate, dimethyl fumarate, diethyl maleate, diisopropyl itaconate; methyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, dodecyl vinyl ether Vinyl ethere Monomers; Ethylenically unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile; Vinyl halide monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; Allyl such as allyl acetate and allyl chloride Compound; sulfonic acid group-containing monomer such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid; and 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamidopropyltrimethyl Examples include quaternary ammonium group-containing monomers such as ammonium chloride; vinyltrimethoxysilane.

  The saponification degree of the carboxylic acid vinyl ester polymer varies depending on the presence or absence of the modifying group and the type thereof, but from the viewpoint of water solubility of the resulting vinyl alcohol polymer, it is 40 to 99.99 mol%. It is preferable that it is 50 to 99.9 mol%, more preferably 60 to 99.5 mol%. When the degree of saponification is less than 40 mol%, the dispersion stability of the polymer particles decreases. The viscosity average polymerization degree of the carboxylic acid vinyl ester polymer is usually 50 to 8,000, preferably 100 to 6,000, more preferably 100 to 5,000.

The amount of the alcoholic hydroxyl group-containing water-soluble polymer compound used is preferably 0.5 to 100 parts by weight, more preferably 0.5 to 50 parts by weight, particularly 100 parts by weight of the monomer used for the polymerization. Preferably it is 1-20 weight part. When a polymer latex obtained by using a water-soluble polymer compound in this range is used, a product excellent in oil resistance and blocking resistance and more easily disaggregated can be obtained.
If the amount used is too small, the stability during polymerization tends to decrease and a large amount of agglomerates are generated, and the mechanical and chemical stability of the resulting polymer latex tends to decrease. On the other hand, if the amount is too large, it tends to be difficult to remove reaction heat due to an increase in the viscosity of the polymerization system, or the viscosity of the obtained polymer latex becomes too high to make it difficult to handle.

  In the production of the polymer latex, various surfactants such as nonionic, anionic, cationic or amphoteric surfactants that are usually used in emulsion polymerization are used in a range that does not substantially impair the effects of the present invention. Although it may be used in combination, it is preferable not to use it. When the surfactant is used in combination, the amount used is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less per 100 parts by weight of the monomer used for the polymerization.

  There are no particular restrictions on the method of adding the monomer. For example, the method of adding the entire amount to the reaction vessel before the start of polymerization or the monomer is added to the reaction vessel continuously or intermittently in parallel with the polymerization reaction. A method of adding a part to the reaction vessel before the start of polymerization and starting the polymerization, and then adding the remainder at a specific time, a part of the reaction vessel being charged before starting the polymerization and starting the polymerization Then, the method of adding the remainder to the polymerization system continuously or intermittently can be employed. Especially, the method of adding a monomer to a reaction container continuously can be employ | adopted in parallel with a polymerization reaction at the point which is excellent in polymerization stability.

  The rate of addition of the monomer when the monomer is continuously added to the reaction vessel is not particularly limited, but the polymerization conversion rate in the polymerization system (this polymerization conversion rate is already in the reaction vessel at that time). The polymerization conversion rate relative to the total amount of added monomers) is preferably controlled so as to maintain 10% by weight or more, more preferably 20% by weight or more, and still more preferably 30% by weight or more. If this addition rate is too fast, the polymerization stability tends to be reduced and coarse agglomerates tend to be generated. On the other hand, if it is too slow, the viscosity of the polymerization system increases and it becomes difficult to remove the heat of polymerization reaction. Tend.

  There is no particular limitation on the method of adding the alcoholic hydroxyl group-containing water-soluble polymer compound. For example, the method of introducing the entire amount into the reaction vessel before the start of polymerization or the alcoholic hydroxyl group-containing water-soluble polymer in parallel with the polymerization reaction. A method of adding a compound continuously or intermittently to a reaction vessel, a method of adding a part to a reaction vessel before the start of polymerization and starting the polymerization, and then adding the remainder at a specific time, before the start of polymerization A method may be employed in which a part of the reaction vessel is charged and polymerization is started, and then the remainder is continuously or intermittently added to the polymerization system. Among them, a method of continuously adding an alcoholic hydroxyl group-containing water-soluble polymer compound to the reaction vessel in parallel with the polymerization reaction can be preferably employed from the viewpoint of excellent polymerization stability.

  As a method for adding the monomer and the alcoholic hydroxyl group-containing water-soluble polymer compound, both may be added separately to the reaction vessel, or both may be mixed and added to the reaction vessel. Among them, a method of mixing both of them and adding them to a reaction vessel is preferable because of excellent polymerization stability, and a monomer, a monomer obtained by mixing an alcoholic hydroxyl group-containing water-soluble polymer compound and an aqueous medium. A method of adding the emulsion to the reaction vessel is more preferably employed.

In the production of the polymer latex, it is preferable that the monomer is polymerized in the presence of alcohol. By performing the polymerization in the presence of alcohol, the polymerization reaction can be stably performed while suppressing the generation of coarse aggregates.
The alcohol that can be used here is not particularly limited and may be monovalent or polyvalent, but is preferably water-soluble. Specific examples of such alcohols include methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol and the like.
The amount of alcohol used is preferably 1 to 50 parts by weight, more preferably 2 to 20 parts by weight, based on 100 parts by weight of the monomer used for the polymerization.

  There are no particular restrictions on the method of adding the alcohol. For example, a method in which the entire amount is charged into the reaction vessel before the start of polymerization, or a part of the reaction vessel before the start of polymerization is charged to start the polymerization, and then the remaining part is specified. For example, a method of additionally adding at the time, a method of adding a part to the reaction vessel before starting the polymerization and starting the polymerization, and then adding the remainder continuously or intermittently to the polymerization system may be employed. Of these, a method in which the entire amount is charged into the reaction vessel before the start of polymerization can be preferably employed.

Although it will not specifically limit as a polymerization initiator if it is a radical polymerization initiator, It is preferable to use what generate | occur | produces a peroxide radical.
Specific examples of the polymerization initiator that generates peroxide radicals include, for example, water-soluble peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide; t-butyl hydroperoxide, benzoyl peroxide, di-t -Oil-soluble peroxides such as butyl peroxide; redox initiators in combination with peroxides and various reducing agents such as sodium bisulfite. Of these, water-soluble peroxides are preferable, and persulfate is particularly preferable.
The usage-amount of a polymerization initiator is 0.05-5 weight part normally with respect to 100 weight part of monomers, Preferably it is 0.1-4 weight part.
There is no particular limitation on the method for adding the polymerization initiator. A method of additionally adding at a specific time, a method of adding a part to the reaction vessel before starting the polymerization and starting the polymerization, and then adding the remainder to the polymerization system continuously or intermittently can be employed.

  In the polymerization, a chain transfer agent can be used as necessary. The chain transfer agent is not particularly limited as long as chain transfer occurs. For example, n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-stearyl mercaptan , Compounds having a mercapto group such as thioglycolic acid, thiomalic acid, 2-ethylhexylthioglycolate; xanthogen compounds such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide; α-methylstyrene dimer, 2,4-diphenyl-4- Α-methylstyrene dimers such as methyl-1-pentene, 2,4-diphenyl-4-methyl-2-pentene, 1,1,3-trimethyl-3-phenylindane; tetramethylthiuram disulfide, Thiuram compounds such as traethylthiuram disulfide and tetramethylthiuram monosulfide; phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; allyl such as allyl alcohol, acrolein and methacrolein Compound: Halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, carbon tetrachloride, carbon tetrabromide; α-benzyloxystyrene, α-benzyloxyacrylonitrile, α-benzyloxyacrylamide, terpinolene, triphenylethane, pentaphenylethane And so on. These chain transfer agents may be used alone or in combination of two or more.

  When a chain transfer agent is used, the amount used is usually 5 parts by weight or less with respect to 100 parts by weight of the monomer. The method for adding the chain transfer agent is not particularly limited, and it may be added all at once or intermittently or continuously to the polymerization system.

  In the polymerization, in addition to those described above, polymerization auxiliary materials such as a particle size adjusting agent, a chelating agent, an oxygen scavenger, a dispersing agent, a pH adjusting agent, and an inorganic salt that are usually used in emulsion polymerization can be appropriately used. .

  Although there is no restriction | limiting in particular in superposition | polymerization temperature, Usually, 0-100 degreeC, Preferably it is 50-95 degreeC.

  The polymerization reaction is performed as described above, and when the predetermined polymerization conversion rate is reached, a polymerization terminator is added or the polymerization system is cooled to stop the polymerization reaction. The polymerization conversion rate when stopping the polymerization reaction is preferably 92% by weight or more, more preferably 95% by weight or more. After stopping the polymerization reaction, if desired, the unreacted monomer is removed, and the pH and solid content concentration are adjusted to obtain a polymer latex.

The glass transition temperature of the polymer is -20 to 50 ° C, preferably -10 to 45 ° C. If the glass transition temperature is low, the blocking resistance and disaggregation properties are inferior. On the other hand, if the glass transition temperature is high, it is difficult to form a film of polymer latex, so that satisfactory oil-resistant paper cannot be obtained.
In addition, this glass transition temperature can be adjusted by selecting the kind and usage-amount suitably from the said monomer according to a conventional method.

The polymer constituting the polymer latex is preferably a combination of a polymer derived from the monomer used for polymerization and a part of the alcoholic hydroxyl group-containing water-soluble polymer compound used for the polymerization. .
The amount of the alcoholic hydroxyl group-containing water-soluble polymer compound bonded to the polymer derived from the monomer used for the polymerization (hereinafter sometimes referred to as “grafting ratio”) is derived from the monomer used for the polymerization. It is preferably 0.5 to 50% by weight, more preferably 0.5 to 20% by weight, and particularly preferably 1 to 15% by weight based on the total amount of the polymer to be processed.
If the graft ratio is too small, it is difficult to ensure oil resistance. Conversely, if the graft ratio is too large, the viscosity of the latex tends to increase, making it difficult to handle.

  The volume average particle diameter of the polymer latex is preferably 80 to 800 nm, more preferably 100 to 600 nm. When the particle diameter is in the above range, a water and oil resistant paper excellent in balance of water resistance and oil resistance can be obtained. The particle size can be adjusted by appropriately selecting the type and amount of the alcoholic hydroxyl group-containing water-soluble polymer compound and the amount of the polymerization initiator used.

  If necessary, additives such as conventionally known pH adjusters, antifoaming agents, antiseptics, antibacterial agents, anti-aging agents, ultraviolet absorbers, fluidity improvers, antiblocking agents and the like are appropriately added to the polymer latex. be able to.

  The polymer latex for oil-resistant paper of the present invention has an odor intensity of 200,000 or less measured according to JIS K 0101 for a solid content of 30% by weight. This odor intensity is preferably 150,000 or less, more preferably 100,000 or less. When oil-resistant paper is produced using a polymer latex having a high odor strength, the oil-resistant paper has a strong odor and is not suitable for use in food packaging.

  In the method for producing a polymer latex for oil-resistant paper of the present invention, after obtaining the polymer latex, 30 to 200 parts by weight of water vapor is added to the polymer latex with respect to 100 parts by weight of the solid content of the polymer latex. And steam distillation.

  The total amount of water vapor blown is 30 to 200 parts by weight, preferably 40 to 180 parts by weight, and more preferably 50 to 150 parts by weight with respect to 100 parts by weight of the polymer latex solid content. If this amount is small, the odor intensity becomes large, while if it is large, coarse aggregates are generated, or the heating time becomes long, and the polymer latex is altered and the oil resistance is lowered.

  The water vapor temperature is usually 100 ° C. or higher, preferably 100 to 140 ° C., more preferably 101 to 120 ° C.

The blowing rate of water vapor is preferably 1 to 50 parts by weight per hour and more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the polymer latex solid content.
The pressure in the system during steam distillation may be any state from a reduced pressure state to a pressurized state, but is preferably in the range of −80 kPa to 0 kPa (gauge pressure), and −60 kPa to −10 kPa (gauge). Pressure) is more preferable.
Moreover, it is preferable to steam-distill so that the latex temperature in a system may maintain 80-100 degreeC, More preferably, 85-100 degreeC.

  Prior to steam distillation, for example, unreacted monomers having a relatively low boiling point such as 1,3-butadiene may be removed under heating or non-heating under normal pressure or reduced pressure.

The oil-resistant paper coating composition of the present invention contains the oil-resistant paper polymer latex as a main component.
The content (in terms of solid content) of the oil-resistant paper polymer latex in the oil-resistant paper coating composition is preferably 50% by weight or more, more preferably 70% by weight or more. Of course, only the polymer latex for oil-resistant paper can be used as the oil-resistant paper coating composition.

The oil-resistant paper coating composition of the present invention can contain, for example, a pigment, a wax emulsion, a water-soluble polymer, and the like.
Examples of the pigment include inorganic pigments such as clay, kaolin, talc, calcium carbonate, aluminum hydroxide, silica, barium sulfate, mica, titanium oxide, and satin white; and organic pigments such as plastic pigments. The blending amount of the pigment is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and particularly preferably 10 parts by weight or less with respect to 100 parts by weight of the solid content of the oil-resistant paper polymer latex.

  Examples of the wax emulsion include emulsions made of paraffin wax, polyethylene wax, and microcrystalline wax. The blending amount of the wax emulsion is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, based on 100 parts by weight of the solid latex content of oil-resistant paper.

  The oil-resistant paper coating composition of the present invention may contain a polymer latex other than the oil-resistant paper polymer latex as long as the effects of the present invention are not substantially impaired.

  If desired, the coating composition for oil-resistant paper of the present invention includes, for example, a dispersant, a plasticizer, an antifoaming agent, a pH adjuster, an anti-aging agent, an antiseptic, an antibacterial agent, a fluidity improver, and an anti-blocking agent. Additives such as can be added as appropriate.

  The oil-resistant paper of the present invention is obtained by coating the base paper with the oil-resistant paper coating composition.

The base paper may be either paperboard or western paper, and those having a basis weight of 10 to 1500 g / m ² can be used. In addition, the base paper may be a paper provided with water resistance beforehand by a sizing agent, a coated paper coated with a pigment, or a printed paper.

The coating method is not particularly limited, and for example, a coating apparatus such as a blade coater, a roll coater, an air knife coater, a curtain coater, or a short dwell coater can be used. Oil-resistant paper is obtained by drying after coating.
The drying temperature is usually 50 ° C. or higher.

Coating amount is in terms of solid content of the oil paper for coated composition, per side, preferably 1 to 30 g / m ^2, more preferably at 3 to 15 g / m ^2.

  After coating, a smoothing treatment may be performed through a finishing device such as a super calender or a soft nip calender.

  The oil-resistant paper of the present invention can be suitably used as a food sheet, a dish, a cup, a wrapping paper, and a packaging box containing oil and fat such as fried potato, fried chicken, tempura, croquette, bread, snack confectionery, and Western confectionery.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In Examples, “%” and “parts” are all based on weight unless otherwise specified.

Evaluation was performed as follows.
Evaluation method of polymer latex (glass transition temperature of polymer latex)
The obtained polymer latex was cast into a glass mold to prepare a dry film having a thickness of 0.3 mm. About this film, it measured in the measurement temperature range of -100-150 degreeC with the temperature increase rate of 10 degree-C / min using the differential scanning calorimeter.
(Volume average particle diameter of polymer latex)
It measured using the light-scattering particle diameter measuring device (Coulter LS230: the Coulter company make).

(Graft ratio in polymer latex)
The solid content concentration of the obtained polymer latex is adjusted to 10%, and 60 g thereof is used as a sample. The sample is centrifuged at 13,000 rpm for 60 minutes at 5 ° C., and 40 g of the supernatant is recovered. After adding 40 g of distilled water to the sedimented layer (20 g) to make it uniform, the solution is centrifuged again under the same conditions to recover 40 g of the supernatant and the same operation is repeated again for the sedimented layer. A total of 120 g of the solid content of the supernatant obtained by three times of centrifugation is measured, and the amount of solid content in the supernatant is calculated. This is the amount (A) of polyvinyl alcohol that did not bind to the polymer produced by polymerization. By subtracting (A) from the weight (B) of the total polyvinyl alcohol calculated from the charge in the sample, the amount (C) of polyvinyl alcohol bound to the polymer produced by the polymerization is obtained. From these values, the graft ratio is expressed by the following formula (the amount (%) of the alcoholic hydroxyl group-containing water-soluble polymer compound bonded to the polymer with respect to 100 parts of the polymer derived from the monomer used for the polymerization). Calculate
Graft rate = [C / (6-B)] × 100 (%)

(Odor intensity)
Using a polymer latex with a solid content adjusted to 30% as a sample, JIS K
Odor intensity (times) was measured according to 0101. The smaller this value, the smaller the amount of odorous component in the polymer latex.

Oil-resistant paper evaluation method (oil resistance)
TAPPI (Technical Association of Pulp and Paper Industry) According to the provisions of UM-557, one drop of a test solution consisting of castor oil, toluene and n-heptane with different mixing ratios was dropped on the coated surface of oil-resistant paper, and 15 seconds later Wipe off the test solution dripped with tissue paper. If a clear black dot is observed even if the stain due to the penetration of the test liquid on the coated surface, that is, the oil is infiltrated and no soiled portion is generated, it is rejected, and the maximum liquid number that passes is shown as the oil resistance. The larger this value, the better the oil resistance.
Table 1 shows the mixing ratio and oil resistance of the test solutions.

(Blocking resistance)
The coated surface of the oil-resistant paper and the commercially available high-quality paper face each other, and it is passed once between the 150 ° C. heating roll and the elastic roll so that the high-quality paper contacts the heating roll under the condition of a linear pressure of 100 kg / cm. It was. After the temperature of the test specimen after the treatment returned to room temperature, the water-resistant and oil-resistant paper and the high-quality paper were peeled off by hand and evaluated according to the following criteria. One sample is tested 10 times and is shown as a simple averaged score.
5 points: peels cleanly.
4 points: The fine paper is fused to a portion of less than 10%.
3 points: The high-quality paper is fused to the portion of 10 to 30%.
2 points: The fine paper is fused to the portion exceeding 30% and 50% or less.
1 point: The high-quality paper is fused to a portion exceeding 50% of the coating liquid.

(Disaggregation)
The oil-resistant paper is cut to produce a test piece having a size of 3 cm × 3 cm. The total number of the test pieces is 10 g (however, if the weight of these test pieces is less than 10 g, one additional piece of oil-resistant paper is further cut to make the total amount 10 g). Add to 500 g of tap water at ℃. This was put into a mixer and stirred for 10 minutes to perform disaggregation. The obtained slurry was taken out and hand-made into a size of 20 cm × 25 cm and dried in an oven at 120 ° C. for 20 minutes. The undissolved material (coating piece, paper piece, etc.) in the obtained sheet was visually observed and evaluated.
When the largest undissolved material is less than 2 mm square, when it is less than 2 mm square to less than 5 mm square Δ, when it exceeds 5 mm square, it is indicated by ×, and the following judgments were made.
○: Excellent disaggregation.
(Triangle | delta): Disaggregation property is a little inferior.
X: The disaggregation property is inferior.

(Odor: Calmore Σ increase value)
The coated paper cut into 20 cm square was put into a glass container with an internal volume of 100 ml, sealed with a lid, and then left in a constant temperature bath at 40 ° C. for 4 hours. Then, the lid | cover of the taken-out glass container was removed, and the maximum value of the Calmore Σ value inside a glass container was measured using the smell component measuring apparatus (KALMOR-Σ: product made by Calmore).
The Calmore Σ increase value was obtained by subtracting the Calmore Σ value in the measurement chamber separately measured from the maximum value of the Calmore Σ value. The smaller the numerical value, the smaller the odor component. If it is approximately 200 or less, it is not perceived as an unpleasant odor.

Example 1
(Manufacture of polymer latex)
In a pressure vessel, 130 parts of deionized water, 56 parts of styrene, 4 parts of methacrylic acid, 40 parts of 1,3-butadiene and polyvinyl alcohol (viscosity average polymerization degree 500, saponification degree 88 mol%; PVA-205, manufactured by Kuraray Co., Ltd.) ) 15 parts were charged and mixed and stirred to obtain a monomer emulsion.
A pressure resistant reactor was charged with 47 parts of deionized water and 4 parts of ethanol and heated to 80 ° C. While maintaining 80 ° C., after adding an aqueous solution of 2.0 parts of potassium persulfate in 35 parts of deionized water, the monomer emulsion was continuously added to the reactor for 4 hours and 30 minutes. Added to. After completing the addition of the monomer mixture, the reaction was continued for another 3 hours, and then the polymerization reaction was stopped by cooling the polymerization system. The polymerization conversion rate at this time was 96%.

  Into the obtained polymer latex, with respect to 100 parts of the solid content of the polymer latex, steam at 115 ° C. corresponding to 100 parts was blown in at a constant blowing speed for 10 hours and at a reduced pressure of −40 kPa. Steam distillation was performed. Thereafter, the solid content concentration and pH were adjusted to obtain a polymer latex A having a solid content concentration of 30% and a pH of 7. The physical properties of the polymer latex A were measured, and the results are shown in Table 2.

(Manufacture of oil-resistant paper)
Polymer latex A was applied to one side of a coated white ball base paper having a weight of 310 g / m ^{2 so} as to have a dry solid content of 6 g / m ^2, and dried with a hot air dryer at 100 ° C. for 30 seconds. Thereafter, an oil-resistant paper was obtained by leaving it in a constant temperature and humidity room at a temperature of 23 ° C. and a relative humidity of 65% for one day. The oil resistance, blocking resistance, disaggregation and odor of this oil resistant paper were evaluated and the results are shown in Table 2.

(Examples 2 to 4)
Polymer latexes B to D were obtained in the same manner as in Example 1 except that the monomer composition, polyvinyl alcohol amount, blowing water vapor amount, and water vapor blowing speed shown in Table 2 were changed. Table 2 shows the physical properties of these polymer latexes.
Oil-resistant paper was obtained in the same manner as in Example 1 except that the polymer latexes B to D were used in place of the polymer latex A. The physical properties of the oil-resistant paper were measured, and the results are shown in Table 2.

(Comparative Examples 1 and 2)
Polymer latexes E and F were obtained in the same manner as in Example 1 except that the monomer composition, the amount of water vapor blown, and the water vapor blowing speed shown in Table 2 were changed. Table 2 shows the physical properties of these polymer latexes.
Oil-resistant paper was obtained in the same manner as in Example 1 except that the polymer latex E and F were used in place of the polymer latex A. The physical properties of the oil-resistant paper were measured, and the results are shown in Table 2.

(Comparative Example 3)
In a pressure vessel, add 50 parts of deionized water, 0.2 part of sodium lauryl sulfate, 26 parts of methyl methacrylate, 50 parts of butyl acrylate, 20 parts of acrylonitrile and 4 parts of methacrylic acid, and mix and stir the monomer. An emulsion was obtained.
To the pressure-resistant reactor, 60 parts of deionized water and 0.6 part of sodium lauryl sulfate were added, and the temperature was raised to 80 ° C. While maintaining 80 ° C., after adding an aqueous solution in which 0.5 part of potassium persulfate was dissolved in 10 parts of deionized water, the monomer emulsion was continuously added to the reactor over 4 hours. did. After the addition of the monomer emulsion was completed, the reaction was continued for another 2 hours, and then the polymerization system was cooled to stop the polymerization reaction. The polymerization conversion rate at this time was 98%.

  Into the obtained polymer latex, with respect to 100 parts of the solid content of the polymer latex, steam at 115 ° C. corresponding to 132 parts was blown in at a constant blowing speed for 11 hours and at a reduced pressure of −40 kPa. Steam distillation was performed. Thereafter, the solid content concentration and the pH were adjusted to obtain a polymer latex G having a solid content concentration of 30% and a pH of 7. The physical properties of the polymer latex G were measured, and the results are shown in Table 2.

The following can be seen from Table 2.
When the polymer latex E having a glass transition temperature lower than the lower limit specified in the present invention is used, the resulting oil-resistant paper is inferior in blocking resistance and disaggregation (Comparative Example 1).
The oil-resistant paper obtained by using the polymer latex F having a high odor strength obtained by steam distillation by blowing a small amount of water vapor has many odor components and is not suitable for food packaging (Comparative Example 2).
When the polymer latex G obtained by polymerizing a monomer in the presence of an anionic surfactant usually used in emulsion polymerization is used, the resulting oil-resistant paper is inferior in oil resistance (Comparative Example 3).
Compared with these comparative examples, when the polymer latex for oil-resistant paper of the present invention is used, oil-resistant paper having very little odor and excellent in oil resistance, blocking resistance and disaggregation properties is obtained (Examples 1 to 4). . These oil-resistant papers can also be suitably used for food packaging.

Claims (4)

Conjugated diene monomer, aromatic vinyl monomer, ethylenically unsaturated nitrile monomer and ethylenically unsaturated carboxylic acid in the presence of a vinyl alcohol polymer in an aqueous medium and without using a surfactant Vinyl obtained by polymerizing a monomer mixture comprising at least one selected from alkyl ester monomers and 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer in the total amount of monomers An oil-resistant polymer latex containing a polymer having a glass transition temperature of −10 to 45 ° C. , in which an alcohol polymer is bonded to a polymer derived from the monomer mixture in an amount of 1 to 15% by weight based on the total amount. A polymer latex for oil-resistant paper, wherein the polymer latex having a solid content concentration of 30% by weight has an odor intensity measured according to JIS K 0101 of 100,000 or less . Conjugated diene monomer, aromatic vinyl monomer, ethylenically unsaturated nitrile monomer and ethylenically unsaturated carboxylic acid in the presence of a vinyl alcohol polymer in an aqueous medium and without using a surfactant By polymerizing a monomer mixture comprising at least one selected from alkyl ester monomers and 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer in the total amount of monomers, After obtaining a polymer latex containing a polymer having a glass transition temperature of −10 to 45 ° C. bonded to the polymer derived from the monomer mixture by 1 to 15% by weight based on the total amount of the polymer, A method for producing a polymer latex for oil-resistant paper, wherein 50 to 150 parts by weight of water vapor is blown into the polymer latex with respect to 100 parts by weight of the solid content of the polymer latex, followed by steam distillation. A coating composition for oil-resistant paper comprising the polymer latex for oil-resistant paper according to claim 1 as a main component. An oil resistant paper obtained by coating the base paper with the coating composition for oil resistant paper according to claim 3 .