US20220081842A1

US20220081842A1 - Oil-resistant agent for paper

Info

Publication number: US20220081842A1
Application number: US17/456,739
Authority: US
Inventors: Tetsuya Uehara; Michio Matsuda; Hirotoshi Sakashita; Yuuki Yamamoto; Daisuke Noguchi
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2019-05-28
Filing date: 2021-11-29
Publication date: 2022-03-17
Also published as: CN113891972A; TW202106949A; JPWO2020241709A1; KR20220002428A; EP3978683A1; JP7299526B2; WO2020241709A1; EP3978683A4

Abstract

A paper oil-resistant agent which is added to the interior of paper and includes (1) a non-fluorine polymer and (2) at least one type of particles selected from inorganic particles or organic particles, the amount of the particles (2) being 1-99.9 wt % of the total weight of the non-fluorine polymer (1) and the particles (2). Also disclosed is an oil-resistant paper including the paper oil-resistant agent and a method for producing the oil-resistant paper.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Rule 53(b) Continuation of International Application No. PCT/JP2020/020972 filed May 27, 2020, claiming priority based on Japanese Patent Application No. 2019-099463 filed May 28, 2019, the respective disclosures of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to an oil-resistant agent for paper, and paper treated with the oil-resistant agent for paper.

BACKGROUND ART

Paper may be required to have oil resistance.
For example, food packaging and food containers which are made of paper are required to prevent water and oil contained in food from oozing out. Accordingly, an oil-resistant agent is internally or externally applied to the paper.
Several proposals have been made to impart oil resistance to paper.
Patent Literature 1 (JP 2015-129365 A) discloses a method of forming a cellulose article, comprising: attaching cellulose fibers to a compound comprising an aqueous dispersion comprising at least one polymer selected from the group consisting of an ethylene thermoplastic polymer, a propylene thermoplastic polymer, and a mixture thereof; at least one polymer stabilizer; and water.
Patent Literature 2 (WO 2015/008868 A1) discloses a fine cellulose fiber sheet comprising fine cellulose fibers having an average fiber diameter of 2 nm or more and 1,000 nm or less, wherein a weight ratio of the fine cellulose fibers is 50% to 99% by weight, and the block polyisocyanate aggregate is contained in a weight ratio of 1 to 100% by weight, based on the fine cellulose fiber weight.
Patent Document 3 (JP 2004-148307 A) discloses a method for producing a coated support comprising: a) forming a composite multilayer free-flowing curtain comprising at least two layers imparting barrier functionalities, and b) bringing the curtain into contact with a continuous web support to give a coated support.

CITATION LIST

Patent Literature

Patent Literature 1

JP 2015-129365 A

Patent Literature 2

WO 2015/008868 A1

Patent Literature 3

JP 2004-148307 A

SUMMARY OF INVENTION

Technical Problem

An object of the present disclosure is to provide an oil-resistant agent capable of imparting excellent oil resistance to paper.

Solution to Problem

The present disclosure relates to an oil-resistant agent comprising (1) a fluorine-free polymer and (2) particles selected from inorganic particles and/or organic particles. In the treatment of the paper, the oil-resistant agent may be externally or internally added, and preferably the oil-resistant agent is internally added.
Preferable embodiments of the present disclosure are as follows:
[1]
A paper oil-resistant agent which is added to interior of paper, comprising:

- (1) a fluorine-free polymer, and
- (2) at least one type of particles selected from inorganic particles or organic particles,

wherein an amount of the particles (2) is 1 to 99.9% by weight, based on the total weight of the fluorine-free polymer (1) and the particles (2).
[2]
The paper oil-resistant agent according to [1], wherein the fluorine-free polymer (1) is an acrylic polymer.
[3]
The paper oil-resistant agent according to [1] or [2], wherein the fluorine-free polymer has a repeating unit formed from an acrylic monomer having a long-chain hydrocarbon group (a), and
the acrylic monomer having a long-chain hydrocarbon group (a) is a monomer represented by formula:
CH₂═C(—X¹)—C(═O)—Y¹(R¹)_k
wherein
R¹each is independently a hydrocarbon group having 7 to 40 carbon atoms,
X¹is a hydrogen atom, a monovalent organic group, or a halogen atom,
Y¹is a divalent to a tetravalent group composed of at least one selected from a hydrocarbon group having one carbon atom, —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—, provided that a hydrocarbon group is excluded, and
k is 1 to 3.
[4]
The paper oil-resistant agent according to [3], wherein, in the acrylic monomer having a long-chain hydrocarbon group (a), X¹is a hydrogen atom or a methyl group.
[5]
The paper oil-resistant agent according to any one of [1] to [4], wherein, in the acrylic monomer having a long-chain hydrocarbon group (a), the long-chain hydrocarbon group has 18 or more carbon atoms.
[6]
The paper oil-resistant agent according to any one of [3] to [5], wherein
the acrylic monomer having a long-chain hydrocarbon group (a) is:
(a1) an acrylic monomer represented by formula:
CH₂═C(—X⁴)—C(═O)—Y²—R²
wherein
R²is a hydrocarbon group having 7 to 40 carbon atoms,
X⁴is a hydrogen atom, a monovalent organic group, or a halogen atom, and
Y²is —O— or —NH—, and/or
(a2) an acrylic monomer represented by formula:
CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_n
wherein
R³each is independently a hydrocarbon group having 7 to 40 carbon atoms,
X⁵is a hydrogen atom, a monovalent organic group, or a halogen atom,
Y³is —O— or —NH—,
Y⁴each is independently a group composed of at least one selected from a direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,
Z is a direct bond or a divalent or trivalent hydrocarbon group having 1 to 5 carbon atoms, and
n is 1 or 2.
[7]
The paper oil-resistant agent according to any one of [3] to [6], wherein
the acrylic monomer having a hydrophilic group (b) is at least one oxyalkylene (meth)acrylate represented by formula:
CH₂═CX²C(═O)—O—(RO)_n—X³ (b1),
CH₂═CX²C(═O)—O—(RO)_n—C(═O)CX²═CH₂ (b2), or
CH₂═CX²C(═O)—NH—(RO)_n—X³ (b3)
wherein
X²is a hydrogen atom or a methyl group,
X³is a hydrogen atom or an unsaturated or saturated hydrocarbon group having 1 to 22 carbon atoms,
R each is independently an alkylene group having 2 to 6 carbon atoms, and
n is an integer of 1 to 90.
[8]
The paper oil-resistant agent according to any one of [3] to [7], wherein the fluorine-free polymer further comprises a repeating unit formed from (c) a monomer having an olefinic carbon-carbon double bond and having an anion donating group or a cation donating group, other than the monomers (a) and (b).
[9]
The paper oil-resistant agent according to [8], wherein the anion donating group is a carboxyl group, or the cation donating group is an amino group.
[10]
The paper oil-resistant agent according to any one of [3] to [9], wherein an amount of the repeating unit formed from the acrylic monomer having a long-chain hydrocarbon group (a) is 30 to 90% by weight, based on a copolymer, and an amount of the repeating unit formed from the acrylic monomer having a hydrophilic group (b) is 5 to 70% by weight, based on the copolymer.
[11]
The paper oil-resistant agent according to any one of [1] to [10], wherein the inorganic particles are made of at least one selected from calcium carbonate, talc, kaolin, clay, mica, aluminum hydroxide, barium sulfate, calcium silicate, calcium sulfate, silica, zinc carbonate, zinc oxide, titanium oxide, bentonite, and white carbon, and
the organic particles are made of at least one selected from polysaccharides and thermoplastic resins.
[12]
The paper oil-resistant agent according to any one of [1] to [11], wherein the organic particles are insoluble in water at 40° C.
[13]
The paper oil-resistant agent according to any one of [1] to [12], wherein the inorganic particles are calcium carbonate, and the organic particles are starch.
[14]
The paper oil-resistant agent according to any one of [1] to [13], wherein the particle (2) comprises the organic particles.
[15]
The paper oil-resistant agent according to any one of [1] to [14], further comprising a liquid medium which is water or a mixture of water and an organic solvent.
[16]
Oil-resistant paper comprising the paper oil-resistant agent according to any one of [1] to [15] inside the paper.
[17]
The oil-resistant paper according to [16], which is a molded pulp product.
[18]
The oil-resistant paper according to [16] or [17], which is a food packaging material or a food container.
[19]
A method for producing oil-resistant paper, comprising:
preparing a formulated pulp slurry by adding the oil-resistant agent according to any one of [1] to [15] to a slurry in which pulp is dispersed in an aqueous medium, making an oil-resistant paper intermediate, followed by dehydrating and then drying to obtain the oil-resistant paper.

Advantageous Effects of Invention

In the oil-resistant agent, the fluorine-free polymer is favorably dispersed in an aqueous medium, particularly water.
The oil-resistant agent imparts high oil resistance to paper. The oil-resistant agent can impart high water resistance and high gas barrier properties.

DESCRIPTION OF EMBODIMENT

The oil-resistant agent comprises (1) a fluorine-free polymer, and (2) particles. The oil-resistant agent may be a one-, two-, or three-part liquid. The one-part liquid is a liquid comprising the fluorine-free polymer (1) and the particles (2). The two-part liquid (two components) is a combination of a liquid comprising fluorine-free polymer (1) and a liquid comprising the particles (2) (or only particles (2)). In the three-part liquid (three components), a liquid comprising an additive for paper is added for use. The liquid comprising the particles (2) may be a solid (for example, particles only).

(1) Fluorine-Free Polymer

The fluorine-free polymer may be, for example, an acrylic polymer, polyester polymer, polyether polymer, silicone polymer, or urethane polymer. A polymer having an ester bond, an amide bond, and/or a urethane bond is preferable. Particularly, an acrylic polymer (i.e., a fluorine-free acrylic polymer) is preferable. The acrylic polymer preferably has an ester bond and/or an amide bond.
The fluorine-free polymer may be a homopolymer or a copolymer. The fluorine-free polymer is preferably a copolymer.
A homopolymer has only a repeating unit formed from one monomer. The homopolymer is preferably formed only from an acrylic monomer having a long-chain hydrocarbon group having 7 to 40 carbon atoms.
A copolymer has repeating units formed from two or more monomers.
The fluorine-free polymer preferably has:
(a) a repeating unit formed from an acrylic monomer having a long-chain hydrocarbon group having 7 to 40 carbon atoms, and
(b) a repeating unit formed from an acrylic monomer having a hydrophilic group.
Moreover, the fluorine-free polymer preferably has a repeating unit formed of (c) a monomer having an ion donating group in addition to the monomers (a) and (b).
The fluorine-free polymer may have a repeating unit formed from (d) another monomer, in addition to the monomers (a), (b), and (c).

(a) Acrylic Monomer Having Long-Chain Hydrocarbon Group

The acrylic monomer having a long-chain hydrocarbon group (a) has a long-chain hydrocarbon group having 7 to 40 carbon atoms. The long-chain hydrocarbon group having 7 to 40 carbon atoms is preferably a linear or branched hydrocarbon group having 7 to 40 carbon atoms. The number of carbon atoms of the long-chain hydrocarbon group is preferably 10 to 40, such as 12 to 30, particularly 15 to 30. Alternatively, the number of carbon atoms of the long-chain hydrocarbon group may be 18 to 40 carbon atoms.
The acrylic monomer having a long-chain hydrocarbon group (a) is preferably a monomer represented by formula:
CH₂═C(—X¹)—C(═O)—Y¹(R¹)_k
wherein
R¹each is independently a hydrocarbon group having 7 to 40 carbon atoms,
X¹is a hydrogen atom, a monovalent organic group, or a halogen atom,
Y¹is a divalent to tetravalent group composed of at least one selected from a hydrocarbon group having one carbon atom (particularly, —CH₂—, —CH═), —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—, provided that a hydrocarbon group is excluded, and
k is 1 to 3.
X¹may be a hydrogen atom, a methyl group, halogen excluding a fluorine atom, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group. Examples of X¹include a hydrogen atom, a methyl group, a chlorine atom, a bromine atom, an iodine atom, and a cyano group. X¹is preferably a hydrogen atom, a methyl group, or a chlorine atom. X¹is particularly preferably a hydrogen atom.
Y¹is a divalent to tetravalent group. Y¹is preferably a divalent group.
Y¹is preferably a group composed of at least one selected from a hydrocarbon group having one carbon atom, —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—, provided that a hydrocarbon group is excluded. Examples of the hydrocarbon group having one carbon atom include —CH₂—, —CH═ having a branched structure, and —C═ having a branched structure.
Y¹may be —Y′—, —Y′—Y′—, —Y′—C(═O)—, —C(═O)—Y′—, —Y′—C(═O)—Y′—, —Y′—R′—, —Y′—R′—Y′—, —Y′—R′—Y′—C(═O)—, —Y′—R′—C(═O)—Y′—, —Y′—R′—Y′—C(═O)—Y′—, or —Y′—R′—Y′—R′— wherein
Y′ is a direct bond, —O—, —NH—, or —S(═O)₂—, and
R′ is —(CH₂)_m— wherein m is an integer of 1 to 5, or —C₆H₄— (a phenylene group)
Specific examples of Y¹include —O—, —NH—, —O—C(═O)—, —C(═O)—NH—, —NH—C(═O)—, —O—C(═O)—NH—, —NH—C(═O)—O—, —NH—C(═O)—NH—, —O—C₆H₄—, —O—(CH₂)_m—O—, —NH—(CH₂)_m—NH—, —O—(CH₂)_m—NH—, —NH—(CH₂)_m—O—, —O—(CH₂)_m—O—C(═O)—, —O—(CH₂)_m—C(═O)—O—, —NH—(CH₂)_m—O—C(═O)—, —NH—(CH₂)_m—C(═O)—O—, —O—(CH₂)_m—O—C(═O)—NH—, —O—(CH₂)_m—NH—C(═O)—O—, —O—(CH₂)_m—C(═O)—NH—, —O—(CH₂)_m—NH—C(═O)—, —O—(CH₂)_m—NH—C(═O)—NH—, —O—(CH₂)_m—O—C₆H₄—, —O—(CH₂)_m—NH—S(═O)₂—, —O—(CH₂)_m—S(═O)₂—NH—, —NH—(CH₂)_m—O—C(═O)—NH—, —NH—(CH₂)_m—NH—C(═O)—O—, —NH—(CH₂)_m—C(═O)—NH—, —NH—(CH₂)_m—NH—C(═O)—, —NH—(CH₂)_m—NH—C(═O)—NH—, —NH—(CH₂)_m—O—C₆H₄—, —NH—(CH₂)_m—NH—C₆H₄—, —NH—(CH₂)_m—NH—S(═O)₂—, or —NH—(CH₂)_m—S(═O)₂—NH—, wherein m is 1 to 5, particularly 2 or 4.
Y¹is preferably —O—, —NH—, —O—(CH₂)_m—O—C(═O)—, —O—(CH₂)_m—NH—C(═O)—, —O—(CH₂)_m—O—C(═O)—NH—, —O—(CH₂)_m—NH—C(═O)—O—, —O—(CH₂)_m—NH—C(═O)—NH—, —O—(CH₂)_m—NH—S(═O)₂—, —O—(CH₂)_m—S(═O)₂—NH—, —NH—(CH₂)_m—NH—S(═O)₂—, or —NH—(CH₂)_m—S(═O)₂—NH— wherein m is an integer of 1 to 5, particularly 2 or 4. Y¹is more preferably —O— or —O—(CH₂)_m—NH—C(═O)—, particularly —O—(CH₂)_m—NH—C(═O)—.
R¹is preferably a linear or branched hydrocarbon group. The hydrocarbon group may be particularly a linear hydrocarbon group. The hydrocarbon group is preferably an aliphatic hydrocarbon group, particularly a saturated aliphatic hydrocarbon group, and especially an alkyl group. The number of carbon atoms of the hydrocarbon group is preferably 12 to 30, such as 16 to 26 or 15 to 26, particularly 18 to 22 or 17 to 22.
Examples of the acrylic monomer having a long-chain hydrocarbon group (a) include:
(a1) an acrylic monomer represented by formula:
CH₂═C(—X⁴)—C(═O)—Y²—R²
wherein
R²is a hydrocarbon group having 7 to 40 carbon atoms,
X⁴is a hydrogen atom, a monovalent organic group, or a halogen atom, and
Y²is —O— or —NH—, and
(a2) an acrylic monomer represented by formula:
CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_n
wherein
R³each is independently a hydrocarbon group having 7 to 40 carbon atoms,
X⁵is a hydrogen atom, a monovalent organic group, or a halogen atom,
Y³is —O— or —NH—,
Y⁴each is independently a group composed of at least one selected from a direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,
Z is a divalent or trivalent hydrocarbon group having 1 to 5 carbon atoms, and
n is 1 or 2.

(a1) Acrylic Monomer

The acrylic monomer (a1) is a compound represented by formula:
CH₂═C(—X⁴)—C(═O)—Y²—R²
wherein
R²is a hydrocarbon group having 7 to 40 carbon atoms,
X⁴is a hydrogen atom, a monovalent organic group, or a halogen atom, and
Y²is —O— or —NH—.
The acrylic monomer (a1) is a long-chain acrylate ester monomer wherein Y²is —O— or a long-chain acrylamide monomer wherein Y²is —NH—.
R²is preferably an aliphatic hydrocarbon group, particularly a saturated aliphatic hydrocarbon group, and especially an alkyl group. In R², the number of carbon atoms of the hydrocarbon group is preferably 12 to 30, such as 16 to 26, particularly 18 to 22.
X⁴may be a hydrogen atom, a methyl group, halogen excluding a fluorine atom, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group, and is preferably a hydrogen atom, a methyl group, or a chlorine atom.
Preferable specific examples of the long-chain acrylate ester monomer include lauryl (meth)acrylate, stearyl (meth)acrylate, icosyl (meth)acrylate, behenyl (meth)acrylate, stearyl α-chloroacrylate, icosyl α-chloroacrylate, and behenyl α-chloroacrylate.
Preferable specific examples of the long-chain acrylamide monomer include stearyl (meth)acrylamide, icosyl (meth)acrylamide, and behenyl (meth)acrylamide.

(a2) Acrylic Monomer

The acrylic monomer (a2) is a monomer different from the acrylic monomer (a1). The acrylic monomer (a2) is (meth)acrylate or (meth)acrylamide having a group composed of at least one selected from —O—, —C(═O)—, —S(═O)₂—, or —NH—.
The acrylic monomer (a2) may be a compound represented by formula:
CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_n
wherein
R³each is independently a hydrocarbon group having 7 to 40 carbon atoms,
X⁵is a hydrogen atom, a monovalent organic group, or a halogen atom,
Y³is —O— or —NH—,
Y⁴each is independently a group composed of at least one selected from a direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,
Z is a direct bond or a divalent or trivalent hydrocarbon group having 1 to 5 carbon atoms, and
n is 1 or 2.
R³is preferably an aliphatic hydrocarbon group, particularly a saturated aliphatic hydrocarbon group, and especially an alkyl group. In R³, the number of carbon atoms of the hydrocarbon group is preferably 12 to 30, such as 16 to 26 or 15 to 26, particularly 18 to 22 or 17 to 22.
X⁵may be a hydrogen atom, a methyl group, halogen excluding a fluorine atom, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group, and is preferably a hydrogen atom, a methyl group, or a chlorine atom.
Y⁴may be —Y′—, —Y′—Y′—, —Y′—C(═O)—, —C(═O)—Y′—, —Y′—C(═O)—Y′—, —Y′—R′—, —Y′—R′—Y′—, —Y′—R′—Y′—C(═O)—, —Y′—R′—C(═O)—Y′—, —Y′—R′—Y′—C(═O)—Y′—, or —Y′—R′—Y′—R′— wherein
Y′ each is independently a direct bond, —O—, —NH—, or —S(═O)₂—, and
R′ is —(CH₂)_m— wherein m is an integer of 1 to 5, a linear hydrocarbon group having 1 to 5 carbon atoms and an unsaturated bond, a hydrocarbon group having 1 to 5 carbon atoms and a branched structure, or —(CH₂)_l—C₆H₄—(CH₂)_l— wherein l each is independently an integer of 0 to 5, and —C₆H₄— is a phenylene group.
Specific examples of Y⁴include a direct bond, —O—, —NH—, —O—C(═O)—, —C(═O)—O—, —C(═O)—NH—, —NH—C(═O)—, —NH—S(═O)₂—, —S(═O)₂—NH—, —O—C(═O)—NH—, —NH—C(═O)—O—, —NH—C(═O)—NH—, —O—C₆H₄—, —NH—C₆H₄—, —O—(CH₂)_m—O—, —NH—(CH₂)_m—NH—, —O—(CH₂)_m—NH—, —NH—(CH₂)_m—O—, —O—(CH₂)_m—O—C(═O)—, —O—(CH₂)_m—C(═O)—O—, —NH—(CH₂)_m—O—C(═O)—, —NH—(CH₂)_m—C(═O)—O—, —O—(CH₂)_m—O—C(═O)—NH—, —O—(CH₂)_m—NH—C(═O)—O—, —O—(CH₂)_m—C(═O)—NH—, —O—(CH₂)_m—NH—C(═O)—, —O—(CH₂)_m—NH—C(═O)—NH—, —O— (CH₂)_m—O—C₆H₄—, —NH—(CH₂)_m—O—C(═O)—NH—, —NH—(CH₂)_m—NH—C(═O)—O—, —NH—(CH₂)_m—C(═O)—NH—, —NH—(CH₂)_m—NH—C(═O)—, —NH—(CH₂)_mNH—C(═O)—NH—, —NH—(CH₂)_m—O—C₆H₄—, —NH—(CH₂)_m—NH—C₆H₄— wherein m is an integer of 1 to 5.
Y⁴is preferably —O—, —NH—, —O—C(═O)—, —C(═O)—O—, —C(═O)—NH—, —NH—C(═O)—, —NH—S(═O)₂—, —S(═O)₂—NH—, —O—C(═O)—NH—, —NH—C(═O)—O—, —NH—C(═O)—NH—, or —O—C₆H₄—. Y⁴is more preferably —NH—C(═O)—, —C(═O)—NH—, —O—C(═O)—NH—, —NH—C(═O)—O—, or —NH—C(═O)—NH—.
Z is a direct bond or a divalent or trivalent hydrocarbon group having 1 to 5 carbon atoms, and may have a linear structure or a branched structure. The number of carbon atoms of Z is preferably 2 to 4, particularly 2. Specific examples of Z include a direct bond, —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂—, —CH₂CH═ having a branched structure, —CH₂(CH—)CH₂— having a branched structure, —CH₂CH₂CH═ having a branched structure, —CH₂CH₂CH₂CH₂CH═ having a branched structure, —CH₂CH₂(CH—)CH₂— having a branched structure, and —CH₂CH₂CH₂CH═ having a branched structure.
Z is preferably not a direct bond, and Y⁴and Z are simultaneously not direct bonds.
The acrylic monomer (a2) is preferably CH₂═C(—X⁵)—C(═O)—O—(CH₂)_m—NH—C(═O)—R³, CH₂═C(—X⁵)—C(═O)—O—(CH₂)_m—O—C(═O)—NH—R³, CH₂═C(—X⁵)—C(═O)—O—(CH₂)_mNH—C(═O)—O—R³, or CH₂═C(—X⁵)—C(═O)—O—(CH₂)_mNH—C(═O)—NH—R³,
wherein R³and X⁵are as defined above.
The acrylic monomer (a2) is particularly preferably CH₂═C(—X⁵)—C(═O)—O—(CH₂)_mNH—C(═O)—R³.
The acrylic monomer (a2) can be produced by reacting hydroxyalkyl (meth)acrylate or hydroxyalkyl (meth)acrylamide with long-chain alkyl isocyanate. Examples of the long-chain alkyl isocyanate include lauryl isocyanate, myristyl isocyanate, cetyl isocyanate, stearyl isocyanate, oleyl isocyanate, and behenyl isocyanate.
Alternatively, the acrylic monomer (a2) can also be produced by reacting (meth)acrylate having an isocyanate group in a side chain, such as 2-methacryloyloxyethyl methacrylate, with long-chain alkylamine or long-chain alkyl alcohol. Examples of the long-chain alkylamine include laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, and behenylamine. Examples of the long-chain alkyl alcohol include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and behenyl alcohol.
Preferable examples of the long-chain hydrocarbon group-containing acrylic monomer are as follows:
stearyl (meth)acrylate, behenyl (meth)acrylate, stearyl α-chloroacrylate, behenyl α-chloroacrylate;
stearyl (meth)acrylamide, behenyl (meth)acrylamide;
wherein n is a number of 7 to 40, and m is a number of 1 to 5.
The compounds of the above chemical formulae are acrylic compounds in which the α-position is a hydrogen atom, and specific examples may be methacrylic compounds in which the α-position is a methyl group and α-chloroacrylic compounds in which the α-position is a chlorine atom.
The melting point of the acrylic monomer having a long-chain hydrocarbon group (a) is preferably 10° C. or higher, and more preferably 25° C. or higher.
The acrylic monomer having a long-chain hydrocarbon group (a) is preferably an acrylate in which X¹, X⁴, and X³are hydrogen atoms.
The acrylic monomer (a2) is preferably an amide group-containing monomer represented by formula:
R¹²—C(═O)—NH—R¹³—O—R¹¹wherein
R¹¹is an organic residue having an ethylenically unsaturated polymerizable group,
R¹²is a hydrocarbon group having 7 to 40 carbon atoms, and
R¹³is a hydrocarbon group having 1 to 5 carbon atoms.
R¹¹is an organic residue having an ethylenically unsaturated polymerizable group, and is not limited as long as there is a carbon-carbon double bond. Specific examples include organic residues having an ethylenically unsaturated polymerizable group such as —C(═O)CR¹⁴═CH₂, —CHR¹⁴═CH₂, and —CH₂CHR¹⁴═CH₂, and R¹⁴is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R¹¹may have various organic groups other than the ethylenically unsaturated polymerizable group, e.g., organic groups such as chain hydrocarbons, cyclic hydrocarbons, polyoxyalkylene groups, and polysiloxane groups, and these organic groups may be substituted with various substituents. R¹¹is preferably —C(═O)CR¹⁴═CH₂.
R¹²is a hydrocarbon group having 7 to 40 carbon atoms and preferably an alkyl group, such as a chain hydrocarbon group or a cyclic hydrocarbon group. Among them, a chain hydrocarbon group is preferable, and a linear saturated hydrocarbon group is particularly preferable. The number of carbon atoms of R¹²is 7 to 40, preferably 11 to 27, and particularly preferably 15 to 23.
R¹³is a hydrocarbon group having 1 to 5 carbon atoms, and preferably an alkyl group. The hydrocarbon group having 1 to 5 carbon atoms may be either linear or branched, may have an unsaturated bond, and is preferably linear. The number of carbon atoms of R¹³is preferably 2 to 4, and particularly preferably 2. R¹³is preferably an alkylene group.
The amide group-containing monomer may be a monomer having one type of R¹²(for example, a compound in which R¹²has 17 carbon atoms) or a monomer having a combination of multiple types of R¹²(for example, a mixture of a compound in which R¹²has 17 carbon atoms and a compound in which R¹²has 15 carbon atoms)
An example of the amide group-containing monomer is carboxylic acid amide alkyl (meth)acrylate.
Specific examples of the amide group-containing monomer include palmitic acid amide ethyl (meth)acrylate, stearic acid amide ethyl (meth)acrylate, behenic acid amide ethyl (meth)acrylate, myristic acid amide ethyl (meth)acrylate, lauric acid amide ethyl (meth)acrylate, isostearic acid ethylamide (meth)acrylate, oleic acid ethylamide (meth)acrylate, tert-butylcyclohexylcaproic acid amide ethyl (meth)acrylate, adamantanecarboxylic acid ethylamide (meth)acrylate, naphthalenecarboxylic acid amide ethyl (meth)acrylate, anthracenecarboxylic acid amide ethyl (meth)acrylate, palmitic acid amide propyl (meth)acrylate, stearic acid amide propyl (meth)acrylate, palmitic acid amide ethyl vinyl ether, stearic acid amide ethyl vinyl ether, palmitic acid amide ethyl allyl ether, stearic acid amide ethyl allyl ether, and mixtures thereof.
The amide group-containing monomer is preferably stearic acid amide ethyl (meth)acrylate. The amide group-containing monomer may be a mixture comprising stearic acid amide ethyl (meth)acrylate. In a mixture comprising stearic acid amide ethyl (meth)acrylate, the amount of stearic acid amide ethyl (meth)acrylate is, for example, 55 to 99% by weight, preferably 60 to 85% by weight, and more preferably 65 to 80% by weight, based on the weight of the entirety of the amide group-containing monomer, and the remainder of the monomer may be, for example, palmitic acid amide ethyl (meth)acrylate.

(b) Acrylic Monomer Having Hydrophilic Group

The acrylic monomer having a hydrophilic group (b) is a monomer different from the monomer (a), and is a hydrophilic monomer. The hydrophilic group is preferably an oxyalkylene group (the number of carbon atoms of the alkylene group is 2 to 6). Particularly, the acrylic monomer having a hydrophilic group (b) is preferably polyalkylene glycol mono(meth)acrylate, polyalkylene glycol di(meth)acrylate, and/or polyalkylene glycol mono(meth)acrylamide. Polyalkylene glycol mono(meth)acrylate, polyalkylene glycol di(meth)acrylate, and polyalkylene glycol mono(meth)acrylamide are preferably those represented by general formulae:
CH₂═CX²C(═O)—O—(RO)_n—X³ (b1),
CH₂═CX²C(═O)—O—(RO)_n—C(═O)CX²═CH₂ (b2), or
CH₂═CX²C(═O)—NH—(RO)_n—X³ (b3)
wherein,
X²each is independently a hydrogen atom or a methyl group,
X³each is independently is a hydrogen atom or an unsaturated or saturated hydrocarbon group having 1 to 22 carbon atoms,
R each is independently an alkylene group having 2 to 6 carbon atoms, and
n is an integer of 1 to 90. n may be, for example, 1 to 50, particularly 1 to 30, and especially 1 to 15 or 2 to 15. Alternatively, n may be, for example, 1.
R may be a linear or branched alkylene group such as a group represented by formula —(CH₂)_x— or —(CH₂)_x1—(CH(CH₃))_x2— wherein x1 and x2 are 0 to 6 such as 2 to 5, and the sum of x1 and x2 is 1 to 6; and the order of —(CH₂)_x1— and —(CH(CH₃))_x2— is not limited to the formula shown, and may be random.
In —(RO)_n—, there may be two or more types (such as 2 to 4 types, particularly 2 types) of R, and thus —(RO)_n— may be a combination of, for example, —(R¹O)_n1— and —(R²O)_n2— wherein R¹and R²are mutually different and an alkylene group having 2 to 6 carbon atoms, n1 and n2 are a number of 1 or more, and the sum of n1 and n2 is 2 to 90.
R in general formulae (b1), (b2), and (b3) is particularly preferably an ethylene group, a propylene group, or a butylene group. R in general formulae (b1), (b2), and (b3) may be a combination of two or more types of alkylene groups. In this case, at least one R is preferably an ethylene group, a propylene group, or a butylene group. Examples of the combination of R include a combination of an ethylene group/a propylene group, a combination of an ethylene group/a butylene group, and a combination of a propylene group/a butylene group. The monomer (b) may be a mixture of two or more types. In this case, in at least one monomer (b), R in general formula (b1), (b2), or (b3) is preferably an ethylene group, a propylene group, or a butylene group. Polyalkylene glycol di(meth)acrylate represented by general formula (b2) is not preferably used solely as the monomer (b), and is preferably used in combination with the monomer (b1). In this case as well, the compound represented by general formula (b2) is preferably less than 30% by weight in the monomer (b) used.
Specific examples of the acrylic monomer having a hydrophilic group (b) include, but are not limited to, the following.
CH₂═CHCOO—CH₂CH₂O—H
CH₂═CHCOO—CH₂CH₂CH₂O—H
CH₂═CHCOO—CH₂CH(CH₃)O—H
CH₂═CHCOO—CH(CH₃) CH₂O—H
CH₂═CHCOO—CH₂CH₂CH₂CH₂O—H
CH₂═CHCOO—CH₂CH₂CH(CH₃)O—H
CH₂═CHCOO—CH₂CH(CH₃) CH₂O—H
CH₂═CHCOO—CH(CH₃) CH₂CH₂O—H
CH₂═CHCOO—CH₂CH(CH₂CH₃)O—H
CH₂═CHCOO—CH₂C(CH₃)₂O—H
CH₂═CHCOO—CH(CH₂CH₃) CH₂O—H
CH₂═CHCOO—C(CH₃)₂CH₂O—H
CH₂═CHCOO—CH(CH₃) CH(CH₃)O—H
CH₂═CHCOO—C(CH₃)(CH₂CH₃)O—H
CH₂═CHCOO—(CH₂CH₂O)₂—H
CH₂═CHCOO—(CH₂CH₂O)₄—H
CH₂═CHCOO—(CH₂CH₂O) s-H
CH₂═CHCOO—(CH₂CH₂O)₆—H
CH₂═CHCOO—(CH₂CH₂O)₅—CH₃
CH₂═CHCOO—(CH₂CH₂O)₉—CH₃
CH₂═CHCOO—(CH₂CH₂O)₂₃—CH₃
CH₂═CHCOO—(CH₂CH₂O)₉₀—CH₃
CH₂═CHCOO—(CH₂CH(CH₃)O)₉—H
CH₂═CHCOO—(CH₂CH(CH₃)O)₉—CH₃
CH₂═CHCOO—(CH₂CH(CH₃)O)₁₂—CH₃
CH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—H
CH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃
CH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉
CH₂═CHCOO—(CH₂CH₂O)₂₃—OOC(CH₃) C═CH₂
CH₂═CHCOO—(CH₂CH₂O)₂₀—(CH₂CH(CH₃)O) s-CH₂—CH═CH₂
CH₂═CHCOO—(CH₂CH₂O)₉—H
CH₂═C(CH₃)COO—CH₂CH₂O—H
CH₂═C(CH₃)COO—CH₂CH₂CH₂O—H
CH₂═C(CH₃)COO—CH₂CH(CH₃)O—H
CH₂═C(CH₃)COO—CH(CH₃) CH₂O—H
CH₂═C(CH₃)COO—CH₂CH₂CH₂CH₂O—H
CH₂═C(CH₃)COO—CH₂CH₂CH(CH₃)O—H
CH₂═C(CH₃)COO—CH₂CH(CH₃) CH₂O—H
CH₂═C(CH₃)COO—CH(CH₃) CH₂CH₂O—H
CH₂═C(CH₃)COO—CH₂CH(CH₂CH₃)O—H
CH₂═C(CH₃)COO—CH₂C(CH₃)₂O—H
CH₂═C(CH₃)COO—CH(CH₂CH₃) CH₂O—H
CH₂═C(CH₃)COO—C(CH₃)₂CH₂O—H
CH₂═C(CH₃)COO—CH(CH₃) CH(CH₃)O—H
CH₂═C(CH₃)COO—C(CH₃)(CH₂CH₃)O—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₂—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₄—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₅—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₆—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₉—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₅—CH₃
CH₂═C(CH₃)COO—(CH₂CH₂O)₉—CH₃
CH₂═C(CH₃)COO—(CH₂CH₂O)₂₃—CH₃
CH₂═C(CH₃)COO—(CH₂CH₂O)₉₀—CH₃
CH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₉—H
CH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₉—CH₃
CH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₁₂—CH₃
CH₂═C(CH₃)COO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—H
CH₂═C(CH₃)COO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃
CH₂═C(CH₃)COO—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉
CH₂═C(CH₃)COO—(CH₂CH₂O)₂₃—OOC(CH₃) C═CH₂
CH₂═C(CH₃)COO—(CH₂CH₂O)₂₀—(CH₂CH(CH₃)O) s-CH₂—CH═CH₂
CH₂═CH—C(═O)—NH—CH₂CH₂O—H
CH₂═CH—C(═O)—NH—CH₂CH₂CH₂O—H
CH₂═CH—C(═O)—NH—CH₂CH(CH₃)O—H
CH₂═CH—C(═O)—NH—CH(CH₃) CH₂O—H
CH₂═CH—C(═O)—NH—CH₂CH₂CH₂CH₂O—H
CH₂═CH—C(═O)—NH—CH₂CH₂CH(CH₃)O—H
CH₂═CH—C(═O)—NH—CH₂CH(CH₃) CH₂O—H
CH₂═CH—C(═O)—NH—CH(CH₃) CH₂CH₂O—H
CH₂═CH—C(═O)—NH—CH₂CH(CH₂CH₃)O—H
CH₂═CH—C(═O)—NH—CH₂C(CH₃)₂O—H
CH₂═CH—C(═O)—NH—CH(CH₂CH₃) CH₂O—H
CH₂═CH—C(═O)—NH—C(CH₃)₂CH₂O—H
CH₂═CH—C(═O)—NH—CH(CH₃)CH(CH₃)O—H
CH₂═CH—C(═O)—NH—C(CH₃)(CH₂CH₃)O—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₂—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₄—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₆—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₉—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₉—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₂₃—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₉₀—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₉—H
CH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₉—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₁₂—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—H
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃
CH₂═CH—C(═O)—NH—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉
CH₂═C(CH₃)—C(═O)—NH—CH₂CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₃)O—H
CH₂═C(CH₃)—C(═O)—NH—CH(CH₃) CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH₂CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH(CH₃)O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₃)CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH(CH₃)CH₂CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₂CH₃)O—H
CH₂═C(CH₃)—C(═O)—NH—CH₂C(CH₃)₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH(CH₂CH₃) CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—C(CH₃)₂CH₂O—H
CH₂═C(CH₃)—C(═O)—NH—CH(CH₃)CH(CH₃)O—H
CH₂═C(CH₃)—C(═O)—NH—C(CH₃)(CH₂CH₃)O—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₂—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₄—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₆—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₂₃—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉₀—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₉—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₉—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₁₂—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—H
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃
CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉
The monomer (b) is preferably acrylate or acrylamide in which X²is a hydrogen atom. Particularly, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, or hydroxyethyl acrylamide is preferable.

(c) Monomer Having Ion Donating Group

The monomer having an ion donating group (c) is a monomer different from the monomer (a) and the monomer (b). The monomer (c) is preferably a monomer having an olefinic carbon-carbon double bond and an ion donating group. The ion donating group is an anion donating group and/or a cation donating group.
Examples of the monomer having an anion donating group include monomers having a carboxyl group, a sulfonic acid group, or a phosphoric acid group. Specific examples of the monomer having an anion donating group include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, vinyl sulfonic acid, (meth)allylsulfonic acid, styrenesulfonic acid, phosphoric acid (meth)acrylate, vinylbenzenesulfonic acid, acrylamide tert-butyl sulfonic acid, and salts thereof.
Examples of salts of the anion donating group include alkali metal salts, alkaline earth metal salts, and ammonium salts, such as a methyl ammonium salt, an ethanol ammonium salt, and a triethanol ammonium salt.
In the monomer having a cation donating group, examples of the cation donating group include an amino group and preferably a tertiary amino group and a quaternary amino group. In the tertiary amino group, two groups bonded to the nitrogen atom are the same or different and are preferably an aliphatic group having 1 to 5 carbon atoms (particularly an alkyl group), an aromatic group having 6 to 20 carbon atoms (an aryl group), or an araliphatic group having 7 to 25 carbon atoms (particularly an aralkyl group such as a benzyl group (C₆H₅—CH₂—)). In the quaternary amino group, three groups bonded to the nitrogen atom are the same or different and are preferably an aliphatic group having 1 to 5 carbon atoms (particularly an alkyl group), an aromatic group having 6 to 20 carbon atoms (an aryl group), or an araliphatic group having 7 to 25 carbon atoms (particularly an aralkyl group such as a benzyl group (C₆H₅—CH₂—)). In the tertiary and quaternary amino groups, the remaining one group bonded to the nitrogen atom may have a carbon-carbon double bond. The cation donating group may be in the form of a salt.
A cation donating group which is a salt is a salt formed with an acid (an organic acid or an inorganic acid). Organic acids such as carboxylic acids having 1 to 20 carbon atoms (particularly, monocarboxylic acids such as acetic acid, propionic acid, butyric acid, and stearic acid) are preferable. Dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and salts thereof are preferable.
Specific examples of the monomer having a cation donating group are as follows.
CH₂═CHCOO—CH₂CH₂—N(CH₃)₂and salts thereof (such as acetate)
CH₂═CHCOO—CH₂CH₂—N(CH₂CH₃)₂and salts thereof (such as acetate)
CH₂═C(CH₃)COO—CH₂CH₂—N(CH₃)₂and salts thereof (such as acetate)
CH₂═C(CH₃)COO—CH₂CH₂—N(CH₂CH₃)₂and salts thereof (such as acetate)
CH₂═CHC(O) N(H)—CH₂CH₂CH₂—N(CH₃)₂and salts thereof (such as acetate)
CH₂═CHCOO—CH₂CH₂—N(—CH₃) (—CH₂—C₆H₅) and salts thereof (such as acetate)
CH₂═C(CH₃)COO—CH₂CH₂—N(—CH₂CH₃) (—CH₂—C₆H₅) and salts thereof (such as acetate)
CH₂═CHCOO—CH₂CH₂—N⁺(CH₃)₃Cl⁻
CH₂═CHCOO—CH₂CH₂—N⁺(—CH₃)₂(—CH₂—C₆H₅) Cl⁻
CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃Cl⁻
CH₂═CHCOO—CH₂CH(OH) CH₂—N⁺(CH₃)₃Cl⁻
CH₂═C(CH₃)COO—CH₂CH(OH) CH₂—N⁺(CH₃)₃Cl⁻
CH₂═C(CH₃)COO—CH₂CH(OH) CH₂—N⁺(—CH₂CH₃)₂(—CH₂—C₆H₅) Cl⁻
CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃Br⁻
CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃I⁻
CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃O⁻SO₃CH₃
CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃) (—CH₂—C₆H₅)₂Br⁻
The monomer having an ion donating group (c) is preferably methacrylic acid, acrylic acid, and dimethylaminoethyl methacrylate, and more preferably methacrylic acid and dimethylaminoethyl methacrylate.

(d) Another Monomer

Another monomer (d) is a monomer different from the monomers (a), (b), and (c). Examples of the other monomer include ethylene, vinyl acetate, vinyl chloride, vinyl fluoride, halogenated vinyl styrene, α-methylstyrene, p-methylstyrene, polyoxyalkylene mono(meth)acrylate, (meth)acrylamide, diacetone (meth)acrylamide, methylollated (meth)acrylamide, N-methylol (meth)acrylamide, alkyl vinyl ether, halogenated alkyl vinyl ether, alkyl vinyl ketone, butadiene, isoprene, chloroprene, glycidyl (meth)acrylate, aziridinyl (meth)acrylate, benzyl (meth)acrylate, isocyanate ethyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, short-chain alkyl (meth)acrylate, maleic anhydride, (meth)acrylate having a polydimethylsiloxane group, and N-vinylcarbazole.
The amount of the repeating unit formed from the monomer (a) may be 30 to 95% by weight, preferably 40 to 88% by weight, and more preferably 50 to 85% by weight, based on the fluorine-free polymer (particularly, an acrylic polymer).
The amount of the repeating unit formed from the monomer (b) may be 5 to 70% by weight, preferably 8 to 50% by weight, and more preferably 10 to 40% by weight, based on the fluorine-free polymer.
The amount of the repeating unit formed from the monomer (c) may be 0.1 to 30% by weight, preferably 0.5 to 20% by weight, and more preferably 1 to 15% by weight, based on the fluorine-free polymer.
The amount of the repeating unit formed from the monomer (d) may be 0 to 20% by weight, such as 1 to 15% by weight, particularly 2 to 10% by weight, based on the fluorine-free copolymer.
The weight-average molecular weight of the fluorine-free polymer may be 1,000 to 10,000,000, preferably 5,000 to 8,000,000, and more preferably 10,000 to 4,000,000. The weight-average molecular weight is a value obtained in terms of polystyrene by gel permeation chromatography.
Herein, “(meth)acryl” means acryl or methacryl. For example, “(meth)acrylate” means acrylate or methacrylate.
From the viewpoint of oil resistance, the fluorine-free polymer (particularly, an acrylic polymer) is preferably a random copolymer rather than a block copolymer.
Polymerization for the fluorine-free polymer is not limited, and various polymerization methods can be selected, such as bulk polymerization, solution polymerization, emulsion polymerization, and radiation polymerization. For example, in general, solution polymerization involving an organic solvent, and emulsion polymerization involving water or involving an organic solvent and water in combination, are selected. The fluorine-free copolymer after polymerization is diluted with water to be emulsified in water and thus formed into a treatment liquid.
Herein, it is preferable that after polymerization (for example, solution polymerization or emulsion polymerization, preferably solution polymerization), water is added, and then the solvent is removed to disperse the polymer in water. An emulsifier does not need to be added, and a self-dispersive product can be produced.
Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and methyl acetate, glycols such as propylene glycol, dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone (NMP), dipropylene glycol, tripropylene glycol, and low molecular weight polyethylene glycol, and alcohols such as ethyl alcohol and isopropanol.
For example, peroxide, an azo compound, or a persulfate compound can be used as a polymerization initiator. The polymerization initiator is, in general, water-soluble and/or oil-soluble.
Specific examples of the oil-soluble polymerization initiator preferably include 2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 1,1′-azobis(cyclohexan-1-carbonitrile), dimethyl 2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-isobutyronitrile), benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, cumene hydroperoxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, and t-butyl perpivalate.
Specific examples of the water-soluble polymerization initiator preferably include 2,2′-azobisisobutylamidine dihydrochloride, 2,2′-azobis(2-methylpropionamidine) hydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] sulfate hydrate, 2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] hydrochloride, potassium persulfate, barium persulfate, ammonium persulfate, and hydrogen peroxide.
The polymerization initiator is used in the range of 0.01 to 5 parts by weight, based on 100 parts by weight of the monomers.
In order to regulate the molecular weight, a chain transfer agent such as a mercapto group-containing compound may be used, and specific examples thereof include 2-mercaptoethanol, thiopropionic acid, and alkyl mercaptan. The mercapto group-containing compound is used in the range of 10 parts by weight or less, or 0.01 to 5 parts by weight, based on 100 parts by weight of the monomers.
Specifically, the fluorine-free polymer can be produced as follows.
In solution polymerization, a method is employed that involves dissolving the monomers in an organic solvent, performing nitrogen purge, then adding a polymerization initiator, and heating and stirring the mixture, for example, in the range of 40 to 120° C. for 1 to 10 hours. The polymerization initiator may be, in general, an oil-soluble polymerization initiator.
The organic solvent is inert to and dissolves the monomers, and examples include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and methyl acetate, glycols such as propylene glycol, dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone (NMP), dipropylene glycol, tripropylene glycol, and low molecular weight polyethylene glycol, alcohols such as ethyl alcohol and isopropanol, and hydrocarbon solvents such as n-heptane, n-hexane, n-octane, cyclohexane, methylcyclohexane, cyclopentane, methylcyclopentane, methylpentane, 2-ethylpentane, isoparaffin hydrocarbon, liquid paraffin, decane, undecane, dodecane, mineral spirit, mineral turpen, and naphtha. Preferable examples of the solvent include acetone, chloroform, HCHC 225, isopropyl alcohol, pentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, petroleum ether, tetrahydrofuran, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, trichloroethylene, perchloroethylene, tetrachlorodifluoroethane, trichlorotrifluoroethane, N-methyl-2-pyrrolidone (NMP), and dipropylene glycol monomethyl ether (DPM). The organic solvent is used in the range of 50 to 2,000 parts by weight, such as 50 to 1,000 parts by weight, based on total 100 parts by weight of the monomers.
In emulsion polymerization, a method is employed that involves emulsifying the monomers in water in the presence of an emulsifier, performing nitrogen purge, then adding a polymerization initiator, and stirring the mixture in the range of 40 to 80° C. for 1 to 10 hours for polymerization. As the polymerization initiator, a water-soluble polymerization initiator such as 2,2′-azobisisobutylamidine dihydrochloride, 2,2′-azobis(2-methylpropionamidine) hydrochloride. 2,2′-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] sulfate hydrate, 2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] hydrochloride, potassium persulfate, barium persulfate, ammonium persulfate, or hydrogen peroxide; or an oil-soluble polymerization initiator such as 2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile), 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 1,1′-azobis(cyclohexan-1-carbonitrile), dimethyl 2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-isobutyronitrile), benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, cumene hydroperoxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, or t-butyl perpivalate is used. The polymerization initiator is used in the range of 0.01 to 10 parts by weight, based on 100 parts by weight of the monomers.
In order to obtain a water dispersion of the polymer, that has excellent stability when being left to stand, it is desirable that the monomers are formed into particles in water by using an emulsifying apparatus capable of applying strong crushing energy such as a high-pressure homogenizer or an ultrasonic homogenizer, and polymerized by using an oil-soluble polymerization initiator. Various anionic, cationic, or nonionic emulsifiers can be used as emulsifiers, and are used in the range of 0.5 to 20 parts by weight, based on 100 parts by weight of the monomers. An anionic and/or nonionic and/or cationic emulsifier is preferably used. When the monomers are not completely compatible, a compatibilizer such as a water-soluble organic solvent or a low molecular weight monomer that causes the monomers to be sufficiently compatible is preferably added. By adding a compatibilizer, emulsifiability and copolymerizability can be increased.
Examples of the water-soluble organic solvent include acetone, propylene glycol, dipropylene glycol monomethyl ether (DPM), dipropylene glycol, tripropylene glycol, ethanol, N-methyl-2-pyrrolidone (NMP), 3-methoxy-3-methyl-1-butanol, or isoprene glycol, and the water-soluble organic solvent may be used in the range of 1 to 50 parts by weight, such as 10 to 40 parts by weight, based on 100 parts by weight of water. By adding NMP or DPM or 3-methoxy-3-methyl-1-butanol or isoprene glycol (a preferable amount is, for example, 1 to 20% by weight, and particularly 3 to 10% by weight, based on the composition), the stability of the composition (particularly, the emulsion) is increased. Examples of the low molecular weight monomer include methyl methacrylate, glycidyl methacrylate, and 2,2,2-trifluoroethyl methacrylate, and the low molecular weight monomer may be used in the range of 1 to 50 parts by weight, such as 10 to 40 parts by weight, based on total 100 parts by weight of the monomers.
The amount of the fluorine-free polymer (1) is 0.1 to 99% by weight, based on the total weight of the fluorine-free polymer (1) and the particles (2). The lower limit of the amount of the fluorine-free polymer (1) may be 1% by weight, such as 5% by weight, particularly 10% by weight, and especially 20% by weight or 30% by weight. The upper limit of the amount of the fluorine-free polymer (1) may be 90% by weight, such as 70% by weight, particularly 60% by weight, and especially 50% by weight or 40% by weight.

(2) Particle

The particles (2) comprise at least one type of inorganic particles or organic particles. The particles (2) preferably comprise organic particles. The particles (2) more preferably comprise both inorganic particles and organic particles.
The inorganic particles are particles made of inorganic materials. Examples of the inorganic materials constituting the inorganic particles include calcium carbonate, talc, kaolin (and calcined kaolin), clay (and calcined clay), mica, aluminum hydroxide, barium sulfate, calcium silicate, calcium sulfate, silica, zinc carbonate, zinc oxide, titanium oxide, bentonite, and white carbon. Calcium carbonate, silica, and calcined clay are preferable. Calcium carbonate is particularly preferable.
The organic particles are particles made of organic materials. Examples of the organic materials constituting the organic particles include polysaccharides and thermoplastic resins (such as polyvinyl alcohol, polyolefin, polystyrene). The organic particles (such as particles of polysaccharides and particles of thermoplastic resins) may be modified (for example, cation-modified or anion-modified). Polysaccharides are preferable.
The polysaccharides are biopolymers synthesized in biological systems by the condensation and polymerization of various monosaccharides, including those that have been chemically modified (denatured). Examples of polysaccharides include starch, cellulose, modified cellulose, amylose, amylopectin, pullulan, curdlan, xanthan, chitin, and chitosan. Examples of modified cellulose include hydroxymethyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose.
The polysaccharides are preferably starch. Starch particles have excellent dispersibility in the pulp slurry. The starch may be an undenatured starch. Examples of the starches include rice flour starch, wheat starch, corn starch, potato starch, tapioca starch, sweet potato starch, adzuki bean starch, mung bean starch, kudzu starch, and dogtooth violet starch. The starch may be those that have been denatured, such as enzymatic denaturation, thermochemical denaturation, acetate esterification, phosphate esterification, carboxy etherification, hydroxy etherification, and cationic denaturation. Since it gives high air permeability and high oil resistance, the starch is preferably amphoterized starch (starch having a cation group and an anion group) or cationized starch (starch having a cation group). A combination of amphoterized starch and cationized starch (at a preferred weight ratio of 0.1:9.9 to 4:6 or 0.5:9.5 to 2:8) is preferable since it also increases water resistance.
In the particles (2), the cation group (particularly, the cation group in the amphoterized starch or the cationized starch) may be a cation group similar to the cation group in the monomer having the ion donating group (c), such as an amino group, and the anion group (particularly, the anion group in the amphoterized starch) may be an anion group similar to the anion group in the monomer having the ion donating group (c), such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group.
The particles (2) may have a powdery, granular, fibrous, flaky, or a like form.
The particles (inorganic particles and organic particles) are preferably insoluble in water at 40° C. Insoluble in water means that the solubility in 100 g of water at 40° C. is 1 g or less, such as 0.5 g or less.
The average particle size of the particles may be 0.01 to 100 μm, such as 0.1 to 50 μm, particularly 1.0 to 20 μm.
The average particle size can be measured by a laser diffraction particle size distribution measurement apparatus (applying light scattering theory) using a water dispersion of the particles.
The dissolution temperature of organic particles in water is preferably about 55° C. or more (for example, 60° C. to 100° C.). The “dissolution temperature” means the highest temperature at which the appearance of the liquid changes from cloudy to transparent after adding 5 parts by weight of organic particles based on 100 parts by weight of water maintained at the target temperature with stirring by visual observation under atmospheric pressure (the liquid might be cloudy at the time of addition), and maintaining the liquid at the temperature for 30 minutes with continuous stirring.
Examples of such organic particles that can be dissolved in water are undenatured starch, denatured starch (such as cationized starch), locust bean gum, carboxymethyl cellulose, and polyvinyl alcohol.
The organic particles may be ionic or nonionic. If the pulp is ionic, the organic particles are preferably ionic, more specifically anionic, cationic, or amphoteric organic particles, so that they can be easily anchored to the pulp in the pulp slurry and the product. Particularly, if the pulp is ionic, it is preferable to use organic particles having the opposite ionic part to the pulp, so that the organic particles can be effectively anchored to the pulp (preferably together with an oil-resistant agent) and the gas barrier properties of the finally obtained molded pulp container can be enhanced. Pulps are usually anionic, and for such pulps, it is preferable that the organic particles have a cationic moiety, or more particularly are cationized or amphoterized.
Organic particles having cation moieties include cationized starch, amphoteric starch, and cation-modified polyvinyl alcohol.
The amount of the particles (2) is 1 to 99.9% by weight, based on the total weight of the fluorine-free polymer (1) and the particles (2). The lower limit of the amount of the particles (2) may be 10% by weight, such as 30% by weight or 40% by weight, particularly 50% by weight or 60% by weight, and especially 65% by weight or 70% by weight. The upper limit of the amount of the particles (2) may be 99% by weight or 98% by weight, such as 97% by weight or 95% by weight, particularly 90% by weight, and especially 80% by weight or 70% by weight. Alternatively, the amount of the particles (2) may be 60 to 99% by weight, such as 65 to 98% by weight, particularly 70 to 97% by weight, based on the total weight of the fluorine-free polymer (1) and the particles (2).

(3) Another Component

The oil-resistant agent may comprise another component (3) other than the fluorine-free polymer (1) and the particles (2). Examples of the other component (3) include an aqueous medium and an emulsifier.
The aqueous medium is water or a mixture of water and an organic solvent (an organic solvent miscible with water). The amount of the aqueous medium may be 50% by weight to 99.99% by weight, based on the total amount of the fluorine-free polymer (1) (and the particles (2), if necessary) and the aqueous medium.
The amount of the emulsifier may be 0 to 30 parts by weight, such as 0.1 to 10 parts by weight, based on 100 parts by weight of the fluorine-free polymer (1).

[Oil-Resistant Agent]

The oil-resistant agent may be in the form of a solution, an emulsion, or an aerosol. The oil-resistant agent may comprise the fluorine-free polymer (1) and a liquid medium. The liquid medium is, for example, an organic solvent and/or water, and preferably an aqueous medium. The aqueous medium is water or a mixture of water and an organic solvent (such as polypropylene glycol and/or a derivative thereof).
In the case of a dispersion (emulsion) form, the fluorine-free polymer is a water dispersion type which is dispersed in an aqueous medium, and the fluorine-free polymer (1) may be self-emulsified, dispersed in the aqueous medium in the form of a neutralized salt, or emulsified using an emulsifier.
The particles (2) may be used in the form of solid or dispersed in a liquid medium. The fluorine-free polymer (1) and the particles (2) may be dispersed in the same liquid medium or may be dispersed in different liquid media. In the oil-resistant agent, the concentration of the fluorine-free polymer may be, for example, 0.01 to 50% by weight. The oil-resistant agent may either comprise or not comprise an emulsifier, but it is preferable not to comprise an emulsifier.
The oil-resistant agent can be used to treat a paper substrate. The “treatment” means that the oil-resistant agent is applied to interior and/or exterior of paper.
The oil-resistant agent can be applied to the substrate by a conventionally known method. The oil-resistant agent is mainly present inside the paper through internal treatment.
Examples of the paper substrate to be treated include paper, a container made of paper, and a molded article made of paper (for example, molded pulp).
The fluorine-free polymer favorably adheres to the paper substrate.
The oil-resistant agent should be used such that the amount of fluorine-free polymer (1) and the particles (2) is 0.01 to 75 parts by weight, such as 0.1 to 60 parts by weight, based on 100 parts by weight of pulp solids.

[Papermaking]

Paper can be produced by a conventionally known papermaking method. An internal treatment method in which the oil-resistant agent is added to a pulp slurry before papermaking, or an external treatment method in which the oil-resistant agent is applied to paper after papermaking, can be used. The method of treatment with the oil-resistant agent in the present disclosure is preferably an internal treatment method. Even if the oil-resistant agent of the present disclosure is used in the internal treatment, no new equipment is required.
In the internal treatment method, paper treated by the oil-resistant agent may be produced by mixing the oil-resistant agent with pulp slurry and paper making. The paper treated by the oil-resistant agent is oil-resistant paper having oil resistance. The oil-resistant paper can be thin or thick, or molded pulp.
Paper thus treated, after rough drying at room temperature or high temperature, is optionally subjected to a heat treatment that can have a temperature range of up to 300° C., such as up to 200° C., particularly 80° C. to 180° C., depending on the properties of the paper, and thus shows excellent oil resistance and water resistance.
The present disclosure can be used in gypsum board base paper, coated base paper, wood containing paper, commonly used liner and corrugating medium, neutral machine glazed paper, neutral liner, rustproof liner and metal laminated paper, kraft paper, and the like. The present disclosure can also be used in neutral printing writing paper, neutral coated base paper, neutral PPC paper, neutral heat sensitive paper, neutral pressure sensitive base paper, neutral inkjet paper, and neutral communication paper.
A pulp (pulp raw material) may be any of bleached or unbleached chemical pulp such as kraft pulp or sulfite pulp, bleached or unbleached high yield pulp such as ground pulp, mechanical pulp, or thermomechanical pulp, waste paper pulp such as waste newspaper, waste magazine, waste corrugated cardboard, or waste deinked paper, and non-wood pulp such as bagasse pulp, kenaf pulp, or bamboo pulp. The pulp raw material may be a combination of one or more of these. A mixture of the above pulp raw material and one or more of synthetic fiber of asbestos, polyamide, polyimide, polyester, polyolefin, or the like can be used as well.
In the internal treatment, a pulp slurry having a pulp concentration of 0.5 to 5.0% by weight (such as 2.5 to 4.0% by weight) is preferably formed into paper. An additive (such as a sizing agent, a paper strengthening agent, a flocculant, a retention aid, or a coagulant) and the fluorine-free polymer can be added to the pulp slurry. Since the pulp is generally anionic, at least one of the additive and the fluorine-free polymer is preferably cationic or amphoteric such that the additive and the fluorine-free polymer are favorably anchored to paper. A combination of a cationic or amphoteric additive and an anionic fluorine-free polymer, a combination of an anionic additive and a cationic or amphoteric fluorine-free polymer, and a combination of a cationic or amphoteric additive and fluorine-free polymer are preferably used.
Other components (additives) may be used in addition to the oil-resistant agent. Examples of the other components are cationic coagulants, water-resistant agents, paper strength additives, flocculants, fixing agents, and yield improvers.
Cationic coagulants, paper strength additives, flocculants, fixing agents, and yield improvers can be polymers or inorganic materials which are cationic or amphoteric. The cationic coagulants, paper strength additives, flocculants, fixing agents, and yield improvers can effectively anchor the oil-resistant agent consisting of the fluorine-free polymer (1) and the particles (2) to the pulp, which is generally anionic, and the gas barrier properties and/or water resistance and oil resistance of the finally obtained molded pulp container can be enhanced.
Examples of cationic coagulants, paper strength additives, flocculants, fixing agents, and yield improvers include a polyamine epichlorohydrin resin, a polyamide epichlorohydrin resin, cationic polyacrylamide (an acrylamide-allylamine copolymer, an acrylamide-dimethylaminoethyl (meth)acrylate copolymer, an acrylamide-diethylaminoethyl (meth)acrylate copolymer, an acrylamide-quaternized dimethylaminoethyl (meth)acrylate copolymer, an acrylamide-quaternized diethylaminoethyl (meth)acrylate copolymer, or the like), polydiallyldimethylammonium chloride, polyallylamine, polyvinylamine, polyethyleneimine, an N-vinylformamide-vinylamine copolymer, a melamine resin, a polyamide epoxy resin, sulfate band, PAC (polyaluminum chloride), aluminum chloride, and ferric chloride. Particularly, polyamidepolyamine-epichlorohydrin (PAE), polydiallyldimethylammonium chloride (poly-DADMAC), polyacrylamide (PAM), and the like can be used.
A water-resistant agent may be used in addition to the oil-resistant agent. In the present disclosure, the “water-resistant agent” refers to a component that, when added to the pulp slurry, is capable of increasing the water resistance of a molded pulp product as compared to the case where it is not added (provided that the above-described oil-resistant agent is excluded). Due to the water-resistant agent, the water resistance of the finally obtained molded pulp container can be increased. The above-described cationic coagulant is generally incapable of increasing water resistance by itself and can be understood as being different from the water-resistant agent.
A sizing agent or the like used in ordinary papermaking is usable as a water-resistant agent. Examples of the water-resistant agent include cationic sizing agents, anionic sizing agents, and rosin-based sizing agents (such as acidic rosin-based sizing agents or neutral rosin-based sizing agents), and cationic sizing agents are preferable. Particularly, a styrene-containing polymer such as a styrene-(meth)acrylate copolymer, an alkenyl succinic anhydride, and an alkyl ketene dimer are preferable.
If necessary, a dye, a fluorescent dye, a slime control agent, an antislip agent, an antifoaming agent, and a pitch control agent which are usually used as paper making chemicals in paper treatment agents may also be used.
Paper is preferably a molded pulp product. The molded pulp product can be produced by a producing method comprising: preparing a formulated pulp slurry by adding an oil-resistant agent to a slurry in which pulp is dispersed in an aqueous medium, making a molded pulp intermediate, followed by dehydrating and then at least drying to obtain a molded pulp product.
The preparation of the formulated pulp slurry is preferably performed such that the organic particles remain in a solid state. For example, the formulated pulp slurry is prepared at a temperature lower than, for example, a temperature at least 5° C. lower than the dissolution temperature of the organic particles. In the formulated pulp slurry prepared, the organic particles remain in a solid state (powdery, granular, fibrous, flaky, or the like depending on the organic particles used as a raw material), and for example, when starch powder is used as a raw material, the starch powder may remain dispersed in an aqueous medium.
The oil-resistant agent and the organic particles, and optionally the cationic coagulant and/or the water-resistant agent or the like may be added to the pulp slurry in any order as long as the organic particles remain in a solid state.
The content of each component in the formulated pulp slurry (based on all components) can be suitably selected so as to attain a high freeness suitable for papermaking and dehydrating and the physical properties desired of a molded pulp product, and, for example, can be as follows.
Aqueous medium: 89.5 to 99.89% by weight, particularly 94.5 to 99.69% by weight
Pulp: 0.1 to 5% by weight, particularly 0.3 to 2.5% by weight
Oil-resistant agent (solids): 0.00001 to 1% by weight, particularly 0.0001 to 0.5% by weight
Cationic coagulant (solids): 0 to 1% by weight, particularly 0 to 0.5% by weight (when added, for example, 0.00005% by weight or more)
Water-resistant agent (solids): 0 to 1% by weight, particularly 0 to 0.5% by weight (when added, for example, 0.00005% by weight or more)
When each component is in the form of, for example, a dispersion, the above content indicates the solid content (based on all components) of each component in the formulated pulp slurry.
From another viewpoint, the content of each of the pulp and the oil-resistant agent based on the aqueous medium in the formulated pulp slurry can be suitably selected so as to attain a high freeness suitable for papermaking and dehydrating, and for example, can be as follows.
Pulp: 0.1 to 5.58% by weight, particularly 0.3 to 2.64% by weight
Oil-resistant agent (solids): 0.001 to 2.79% by weight, particularly 0.005 to 1.05% by weight
When the organic particles are dissolved in the aqueous medium (or when an aqueous solution in which the organic particles such as starch are dissolved in advance in the aqueous medium is added to a pulp slurry), the resulting aqueous composition has a reduced freeness. On the other hand, in the formulated pulp slurry, the organic particles remain in a solid state without being dissolved in the aqueous medium, and therefore, as compared to the case where the organic particles are dissolved in the aqueous medium, a larger amount of the organic particles can be added while maintaining the high freeness of the formulated pulp slurry.
Next, the formulated pulp slurry prepared above is made to form a molded pulp intermediate, the molded pulp intermediate is dehydrated and then at least dried to obtain a molded pulp product.
Papermaking, dehydrating, and drying can be performed according to conventionally known methods concerning molded pulp.
For example, by straining the formulated pulp slurry to dehydrate it (for example, by suction and/or pressure reduction) using a mold which has a desired shape and which is provided with numerous holes (and that may be equipped with a filter as necessary), the aqueous medium can be at least partially removed from the formulated pulp slurry, and a molded pulp intermediate having a shape that corresponds to the mold can be obtained.
The process from the preparation to the dehydration of the formulated pulp slurry is performed, with the organic particles remaining in a solid state. For example, after preparation, dehydrating is performed at a temperature lower than, such as a temperature at least 5° C. lower than the dissolution temperature of the organic particles. As for papermaking and dehydrating, the aqueous medium is removed from the formulated pulp slurry through a mold (and optionally a filter), and therefore, an excessively lowered freeness of the formulated pulp slurry due to dissolution of the organic particles makes it substantially impossible to perform papermaking and dehydrating and is thus not preferable. On the other hand, with the organic particles remaining in a solid state, the freeness of the formulated pulp slurry is not lowered, and papermaking and dehydrating can be appropriately performed.
After dehydrating, in the resulting molded pulp intermediate, the organic particles remain in a solid state (powdery, granular, fibrous, flaky, or the like depending on the organic particles used as raw materials) and, for example, when starch powder is used as a raw material, the starch powder may be dispersed in the pulp.
Drying does not need to be performed such that the organic particles remain in a solid state, and can be performed at a temperature at which the remaining aqueous medium can be effectively removed (if applicable, it can be a temperature equal to or higher than the dissolution temperature of the organic particles), for example, 90 to 250° C., particularly 100 to 200° C. The drying time is not limited, and can be selected such that the aqueous medium remaining in the molded pulp intermediate is substantially removed. The drying atmosphere is not limited, and may be conveniently an ambient atmosphere (air under normal pressure).
During and/or after drying, other steps which are conventionally known concerning molded pulp, for example, press molding (including heat pressing), may be performed if necessary.
During drying and/or press molding, causing the organic particles to at least partially dissolve makes it possible to obtain even higher gas barrier properties. The organic particles do not need to dissolve entirely, and the organic particles may partially remain in a solid state.
Thus, a molded pulp product can be produced. This molded pulp product comprises a pulp, an oil-resistant agent, and can achieve high gas barrier properties and excellent water resistance and oil resistance.
In the molded pulp product of the present disclosure, the content of the organic particles based on the pulp is 0.0001 to 75% by weight, such as 0.1 to 60% by weight, particularly 2 to 50% by weight.
When a molded pulp product is obtained by adding an aqueous solution in which organic particles such as starch are dissolved in advance in an aqueous medium to a pulp slurry to increase strength, a sufficient strength improving effect can be obtained even when the content of organic particles based on the pulp is low, and it was thus not required to increase the content of the organic particles based on the pulp.
In the present disclosure, the content of the organic particles based on the pulp is preferably high, and the lower limit of the content of the organic particles based on the pulp may be 3% by weight or 5% by weight, such as 8% by weight or 10% by weight, particularly 15% by weight. The upper limit of the content of the organic particles based on the pulp may be 60% by weight, such as 50% by weight or 40% by weight, particularly 30% by weight or 20% by weight. The content of the organic particles based on the pulp may be 3 to 70% by weight or 5 to 60% by weight, such as 8 to 50% by weight or 8 to 40% by weight. In other words, the content of the organic particles may be 3 to 70 parts by weight or 5 to 60 parts by weight, such as 8 to 50 parts by weight or 8 to 40 parts by weight, based on the 100 parts by weight of the pulp. With such a high content of the organic particles, it is possible to not only obtain high gas barrier properties but also further increase water resistance and oil resistance.
In the molded pulp product, the organic particles may be derived from starch powder dispersed in the aqueous medium (in the formulated pulp slurry).
The proportions of the pulp, the organic particles, the oil-resistant agent, and optionally the cationic coagulant and/or the water-resistant agent contained in the molded pulp product can be considered substantially the same as the solid contents of these components used as raw materials (usually, the aqueous medium and, if present, other liquid media can be removed by drying and press molding, but the solids can remain without being removed or decomposed).
In the molded pulp product, the content of each component (a component that can remain in the molded pulp product) based on the pulp (solids) can be suitably selected according to the physical properties desired of the molded pulp product, and, for example, can be as follows.
Oil-resistant agent (solids): 0.01 to 50% by weight or 0.01 to 20% by weight, particularly 0.05 to 10% by weight
Cationic coagulant (solids): 0 to 20% by weight, particularly 0 to 10% by weight (if present, such as 0.001% by weight or more)
water-resistant agent (solids): 0 to 20% by weight, particularly 0 to 10% by weight (if present, such as 0.001% by weight or more)
The oil-resistant agent are internally added to the molded pulp product (they are added to a pulp slurry, and the molded pulp product is produced by a pulp molding method). Accordingly, after the molded pulp product is used, the entirety of the product can be crushed to bring it back to the original raw materials, and is thus suitable for recycle use. Furthermore, it is possible to utilize the intrinsic biodegradability of the pulp, the molded pulp product can extremely reduce and preferably can substantially eliminate the environmental burden. Also, with the molded pulp product, the texture of the pulp can be maintained on the front side of the product, and the appearance is not impaired unlike when the front side is laminated with a plastic film and becomes glossy.
The molded pulp product can be suitably used as food containers (including trays and the like), for example, storage containers for frozen food and chilled food.
Since the molded pulp product of the present disclosure has excellent water resistance and oil resistance, moisture and oil derived from food do not impregnate the molded pulp product (a container), and it is thus possible to prevent deterioration of container strength resulting from impregnation with water and oil and prevent staining of the table surface or the like facing the bottom surface of the container with moisture and oil permeated through the container. Also, the molded pulp product of the present disclosure has high gas barrier properties and unlikely allows gas and water vapor to permeate, and thus, when accommodating hot and wet food or when heated in a microwave with food being accommodated therein, it is possible to prevent the problem that gas and water vapor derived from food permeate through the container and leak to the outside and, particularly, condense on the table surface or the like facing the bottom surface of the container. Further, the molded pulp product of the present disclosure has high gas barrier properties and unlikely allow gas and water vapor (or moisture) to permeate, and thus, when refrigerating accommodated food, evaporation of water from food and exposure of food to oxygen can be effectively reduced, freezer burn resulting therefrom can be effectively prevented, and the flavor of food can be maintained for a long period of time.
Embodiments have been described above, but it will be understood that various changes to form and detail can be made without departing from the spirit and scope of the claims.

EXAMPLES

Next, the present disclosure will now be described in detail by way of Examples, Comparative Examples, and Test Examples. However, the description of these does not limit the present disclosure.
Below, a part, %, and a ratio indicate a part by weight, % by weight, and a weight ratio, respectively, unless otherwise specified.
The test methods used below are as follows.

[High-Temperature Oil Resistance]

First, 100 ml of an evaluation liquid (corn oil) at 90° C. was poured into a molded pulp product molded into a container shape, the molded pulp product was left to stand still for 30 minutes, then the evaluation liquid was discarded, and the extent of impregnation of the molded pulp product (the container) with the evaluation liquid was visually evaluated according to the following criteria.
4: Almost no oil stains observed in the interior of the bottom of the molded pulp container
3: No oil stains observed on the exterior of the bottom of the molded pulp container
2: Oil stains observed on less than 5% of the exterior area of the bottom of the molded pulp container
1: Oil stains observed on 5% or more and less than 50% of the exterior area of the bottom of the molded pulp container
0: Oil stains observed on 50% or more of the exterior area of the bottom of the molded pulp container

[High-Temperature Water Resistance]

First, 100 ml of an evaluation liquid (tap water) at 90° C. was poured into a molded pulp product molded into a container shape, the molded pulp product was left to stand still for 30 minutes, then the evaluation liquid was discarded, and the extent of impregnation of the molded pulp product (the container) with the evaluation liquid was visually evaluated according to the following criteria.
4: Almost no water stains observed in the interior of the bottom of the molded pulp container
3: No water stains observed on the exterior of the bottom of the molded pulp container
2: Water stains observed on less than 5% of the exterior area of the bottom of the molded pulp container
1: Water stains observed on 5% or more and less than 50% of the exterior area of the bottom of the molded pulp container
0: Water stains observed on 50% or more of the exterior area of the bottom of the molded pulp container

[Air Permeance]

The air permeance (air resistance) at the bottom part of a molded pulp product molded into a container shape was measured in accordance with JIS P 8117 (2009) using an automatic Gurley densometer manufactured by YASUDA SEIKI SEISAKUSHO, LTD. (Product No. 323-AUTO, vent hole diameter 28.6±0.1 mm). The measured value of air permeance was evaluated according to the following criteria.

Evaluation Criteria

Excellent: 500 seconds or more
Good: 300 seconds or more
Fair: 100 seconds or more
Poor: less than 100 seconds

Synthesis Example 1

A reactor having a volume of 500 ml and equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, a nitrogen inlet, and a heater was provided, and 100 parts of a methyl ethyl ketone (MEK) solvent was added. Subsequently, while the solvent is stirred, a monomer composed of 78 parts of stearyl acrylate (StA, melting point: 30° C.), 16 parts of hydroxyethyl acrylate (HEA), and 6 parts of methacrylic acid (MAA) (the monomer being 100 parts in total) as well as 1.2 parts of a perbutyl PV (PV) initiator were added in this order, and the mixture was mixed by being stirred for 12 hours in a nitrogen atmosphere at 65 to 75° C. to carry out copolymerization. The solid content concentration of the resulting copolymer-containing solution was 50% by weight. When the molecular weight of the resulting copolymer was analyzed by gel permeation chromatography, the weight-average molecular weight in terms of polystyrene was 230,000.
As a post-treatment, 142 g of a 0.3% aqueous NaOH solution was added to 50 g of the resulting copolymer solution and dispersed, then MEK was distilled off under reduced pressure while heating the mixture by using an evaporator, and thus a milky white water dispersion of a copolymer was obtained (the content of the volatile organic solvent was 1% by weight or less). Moreover, ion-exchanged water was added to the water dispersion, and thus a water dispersion having a solid content concentration of 15% by weight was obtained.
The melting point of the copolymer was 48° C.

Synthesis Example 2

A reactor having a volume of 500 ml and equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, a nitrogen inlet, and a heater was provided, and 100 parts of a methyl ethyl ketone (MEK) solvent was added. Subsequently, while the solvent is stirred, a monomer composed of 78 parts of stearic acid amide ethyl acrylate (C18AmEA, melting point: 70° C.), 16 parts of hydroxybutyl acrylate (HBA, Tg: −40° C.), and 6 parts of dimethylaminoethyl methacrylate (DM) (the monomer being 100 parts in total) as well as 1.2 parts of a perbutyl PV (PV) initiator were added in this order, and mixed by being stirred for 12 hours in a nitrogen atmosphere at 65 to 75° C. to carry out copolymerization. The solid content concentration of the resulting copolymer-containing solution was 50% by weight.
As a post-treatment, 142 g of a 0.4% aqueous acetic acid solution was added to 50 g of the resulting copolymer solution and dispersed, then the mixture was heated by using an evaporator to distill off MEK under reduced pressure, and thus a light brown copolymer-water dispersion liquid (the content of the volatile organic solvent was 1% by weight or less) was obtained. Moreover, ion-exchanged water was added to the water dispersion, and thus a water dispersion having a solid content concentration of 15% by weight was obtained.

Example 1

2,400 g of a 0.5% by weight of the water dispersion of a mixture of 70 parts of leaf bleached kraft pulp and 30 parts of needle bleached kraft pulp beaten to a freeness (Canadian Freeness) of 550 cc, was added with contiguous stirring. Next, 1.2 g of calcium carbonate was added and kept stirring for 1 minute, and 2.4 g of a 5% solid aqueous solution of amphoterized starch was added and kept stirring for 1 minute. Then, 0.72 g of a 5% solid aqueous solution of alkyl ketene dimer (AKD) was added and kept stirring for 1 minute, and subsequently 3.6 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 diluted with water to a solid content of 10% was added and kept stirring for 1 minute.
The above pulp slurry was placed in a metal tank. In the lower part of the tank, a metal pulp mold with many suction holes was present with a reticular body placed on top of the mold. From the side opposite to the side where the reticular body of the pulp mold was placed, the pulp-containing aqueous composition was suctioned and dehydrated through the pulp mold and the reticular body using a vacuum pump, and the solids (such as a pulp) contained in the pulp-containing aqueous composition were deposited on the reticular body to obtain a molded pulp intermediate. Next, the resulting molded pulp intermediate was dried by applying pressure from top and bottom with metal male and female molds heated to 60 to 200° C. As a result, a molded pulp product molded into a container shape was produced. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 2

2,400 g of a 0.5% by weight of the water dispersion of a mixture of 70 parts of leaf bleached kraft pulp and 30 parts of needle bleached kraft pulp beaten to a freeness (Canadian Freeness) of 550 cc, was added with contiguous stirring. Next, 0.6 g of calcium carbonate was added and kept stirring for 1 minute, and 1.2 g of cationized starch powder was added and kept stirring for 1 minute. Then, 2.4 g of a 5% solid aqueous solution of amphoterized starch was added and kept stirring for 1 minute, and 0.72 g of a 5% solid aqueous solution of alkyl ketene dimer (AKD) was added and kept stirring for 1 minute. Subsequently, 3.6 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 diluted with water to a solid content of 10% was added and kept stirring for 1 minute.
Thereafter, molded pulp products were produced in the same manner as in Example 1, except that the above pulp slurry was used. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 3

The experiment was performed in the same manner as in Example 1, except that 1.2 g of calcium carbonate in Example 2 was added, and 2.4 g of cationized starch powder was added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 4

The experiment was performed in the same manner as in Example 1, except that 2.4 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 in Example 3 diluted with water to a solid content of 10% was added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 5

The experiment was performed in the same manner as in Example 1, except that 4.8 g of cationized starch powder in Example 4 was added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 6

The experiment was performed in the same manner as in Example 1, except that calcium carbonate in Example 5 was not added, and 3.6 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 diluted with water to a solid content of 10% was added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 7

The experiment was performed in the same manner as in Example 1, except that a 5% solid aqueous solution of amphoterized starch in Example 5 was not added, and a 5% solid aqueous solution of alkyl ketene dimer (AKD) was not added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 8

The experiment was performed in the same manner as in Example 1, except that 0.6 g of calcium carbonate in Example 1 was added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 9

The experiment was performed in the same manner as in Example 1, except that 3.6 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 in Example 8 diluted with water to a solid content of 10% was added and kept stirring for 1 minute, and then 6.0 g of the water dispersion of the fluorine-free copolymer of Synthesis Example 1 diluted with water to a solid content of 10% was added and kept stirring for 1 minute. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Example 10

The experiment was performed in the same manner as in Example 1, except that a 5% solid aqueous solution of the alkyl ketene dimer (AKD) in Example 3 was not added. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Comparative Example 1

The experiment was performed in the same manner as in Example 1, except that calcium carbonate in Example 1 was not added, and 3.6 g of styrene-butadiene latex diluted with water to a solid content of 10% was added in place of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 diluted with water to a solid content of 10%. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

Comparative Example 2

The experiment was performed in the same manner as in Example 1 except that 3.6 g of styrene-butadiene latex diluted with water to a solid content of 10% was added in place of the water dispersion of the fluorine-free copolymer of Synthesis Example 2 in Example 2 diluted with water to a solid content of 10%. Table 1 shows the results of evaluating the content of each component based on the pulp in the resulting molded pulp product, as well as high-temperature oil-resistant characteristics, high-temperature water-resistant characteristics, and air permeance.

TABLE 1

						Ex.	Ex.	Ex.	Ex.	Ex.	Com.	Com.
	Ex. 1	Ex. 2	Ex. 3	Ex. 4	Ex. 5	6	7	8	9	10	Ex. 1	Ex. 2

Particles	Inorganic	Calcium	solid %/	10%	5%	10%	10%	10%		10%	5%	5%	10%	5%
	Particles	carbonate	pulp
	Organic	Cationized	solid %/		10%	20%	20%	40%	40%	40%			20%	10%
	Particles	starch	pulp

Aqueous starch	Amphoterized	solid %/	1%	1%	1%	1%	1%	1%		1%	1%	1%	1%	1%
solution	starch	pulp

Water-	Alkyl ketene dimer	solid %/	0.3%	0.3%	0.3%	0.3%	0.3%	0.3%	0.3%	0.3%	0.3%	0.3%
resistant	(AKD)	pulp
agent

Treatment	Acrylic	Syn. Ex. 1	solid %/									5%
agent	polymer		pulp
		Syn. Ex. 2	solid %/	3%	3%	3%	2%	2%	2%	2%	3%	3%	3%
			pulp

	Styrene-butadiene latex	solid %/											3%	3%
		pulp

High-temp. oil-	Corn oil 90° C. × 30 min.	3	3	4	3	4	4	4	2	3	4	0	0
resistance
High-temp. water-	Tap water 90° C. × 30	3	3	3	3	3	3	1	3	3	1	4	4
resistance	min.
Air permeance	Evaluation	Poor	Fair	Ex-	Ex-	Ex-	Ex-	Ex-	Poor	Poor	Ex-	Poor	Fair
				cellent	cellent	cellent	cellent	cellent			cellent
	Measured value (sec.)	37	161	701	718	801	797	783	30	33	687	42	177

INDUSTRIAL APPLICABILITY

The oil-resistant agent of the present disclosure is applicable to a variety of paper, particularly paper for use in a food container and a food packaging material. The oil-resistant agent is externally or internally, particularly internally incorporated into the paper.

Claims

What is claimed is:

1. A paper oil-resistant agent which is added to interior of paper, comprising:

(1) a fluorine-free polymer, and

(2) at least one type of particles selected from inorganic particles or organic particles,

wherein an amount of the particles (2) is 1 to 99.9% by weight, based on the total weight of the fluorine-free polymer (1) and the particles (2).

2. The paper oil-resistant agent according to claim 1, wherein the fluorine-free polymer (1) is an acrylic polymer.

3. The paper oil-resistant agent according to claim 1, wherein the fluorine-free polymer has a repeating unit formed from (a) an acrylic monomer having a long-chain hydrocarbon group, and

the acrylic monomer having a long-chain hydrocarbon group (a) is a monomer represented by formula:

CH₂═C(—X¹)—C(═O)—Y¹(R¹)_k

wherein

R¹each is independently a hydrocarbon group having 7 to 40 carbon atoms,

X¹is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y¹is a divalent to a tetravalent group composed of at least one selected from a hydrocarbon group having one carbon atom, —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—, provided that a hydrocarbon group is excluded, and

k is 1 to 3.

4. The paper oil-resistant agent according to claim 3, wherein, in the acrylic monomer having a long-chain hydrocarbon group (a), X¹is a hydrogen atom or a methyl group.

5. The paper oil-resistant agent according to claim 3, wherein, in the acrylic monomer having a long-chain hydrocarbon group (a), the long-chain hydrocarbon group has 18 or more carbon atoms.

6. The paper oil-resistant agent according to claim 3, wherein

the acrylic monomer having a long-chain hydrocarbon group (a) is:

(a1) an acrylic monomer represented by formula:

CH₂═C(—X⁴)—C(═O)—Y²—R²

wherein

R²is a hydrocarbon group having 7 to 40 carbon atoms,

X⁴is a hydrogen atom, a monovalent organic group, or a halogen atom, and

y²is —O— or —NH—, and/or

(a2) an acrylic monomer represented by formula:

CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_n

wherein

R³each is independently a hydrocarbon group having 7 to 40 carbon atoms,

X⁵is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y³is —O— or —NH—,

Y⁴each is independently a group composed of at least one selected from a direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,

Z is a direct bond or a divalent or trivalent hydrocarbon group having 1 to 5 carbon atoms, and

n is 1 or 2.

7. The paper oil-resistant agent according to claim 3, wherein

the acrylic monomer having a hydrophilic group (b) is at least one oxyalkylene (meth)acrylate represented by formula:

CH₂═CX²C(═O)—O—(RO)_n—X³ (b1)

CH₂═CX²C(═O)—O—(RO)_n—C(═O)CX²═CH₂ (b2), or

CH₂═CX²C(═O)—NH—(RO)_n—X³ (b3)

wherein

X²is a hydrogen atom or a methyl group,

X³is a hydrogen atom or an unsaturated or saturated hydrocarbon group having 1 to 22 carbon atoms,

R each is independently an alkylene group having 2 to 6 carbon atoms, and

n is an integer of 1 to 90.

8. The paper oil-resistant agent according to claim 3, wherein the fluorine-free polymer further comprises a repeating unit formed from (c) a monomer having an olefinic carbon-carbon double bond and having an anion donating group or a cation donating group, other than the monomers (a) and (b).

9. The paper oil-resistant agent according to claim 8, wherein the anion donating group is a carboxyl group, or the cation donating group is an amino group.

10. The paper oil-resistant agent according to claim 3, wherein an amount of the repeating unit formed from the acrylic monomer having a long-chain hydrocarbon group (a) is 30 to 90% by weight, based on a copolymer, and an amount of the repeating unit formed from the acrylic monomer having a hydrophilic group (b) is 5 to 70% by weight, based on the copolymer.

11. The paper oil-resistant agent according to claim 1, wherein the inorganic particles are made of at least one selected from calcium carbonate, talc, kaolin, clay, mica, aluminum hydroxide, barium sulfate, calcium silicate, calcium sulfate, silica, zinc carbonate, zinc oxide, titanium oxide, bentonite, and white carbon, and the organic particles are made of at least one selected from polysaccharides and thermoplastic resins.

12. The paper oil-resistant agent according to claim 1, wherein the organic particles are insoluble in water at 40° C.

13. The paper oil-resistant agent according to claim 1, wherein the inorganic particles are calcium carbonate, and the organic particles are starch.

14. The paper oil-resistant agent according to claim 1, wherein the particles (2) comprises the organic particles.

15. The paper oil-resistant agent according to claim 1, further comprising a liquid medium which is water or a mixture of water and an organic solvent.

16. Oil-resistant paper comprising the paper oil-resistant agent according to claim 1, in interior of the paper.

17. The oil-resistant paper according to claim 16, which is a molded pulp product.

18. The oil-resistant paper according to claim 16, which is a food packaging material or a food container.

19. A method for producing oil-resistant paper, comprising:

preparing a formulated pulp slurry by adding the oil-resistant agent according to claim 1 to a slurry in which pulp is dispersed in an aqueous medium, making an oil-resistant paper intermediate, followed by dehydrating and then drying to obtain the oil-resistant paper.