JP2004076189A - Oil-resistant paper and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide an oil-resistant paper excellent in oil resistance, which can be substituted for a wrapping paper using a conventional fluororesin emulsion, and an oil-resistant paper excellent in water repellency.
An oil-resistant paper having an oil-resistant layer containing an acrylic resin, a styrene-butadiene copolymer and a polyester formed on the surface of a paper substrate, an acrylic resin emulsion, and a styrene-butadiene copolymer latex And, mixed with polyester, after applying the obtained oil-resistant layer-forming resin composition to the surface of the paper substrate, a method for producing an oil-resistant paper, characterized by drying the paper substrate, and A raw material monomer of an acrylic resin is emulsion-polymerized in the presence of a styrene-butadiene copolymer latex, and the obtained acrylic resin as a core, a resin emulsion containing resin particles having a styrene-butadiene copolymer as a shell. , Polyester, and after applying the obtained oil-resistant layer-forming resin composition to the surface of a paper base, drying the paper base. Process for the preparation of oil-resistant paper and butterfly.
[Selection diagram] None

Description

【００５９】
表１に示された結果から、実施例１〜３で得られた耐油性紙は、いずれも、参考例で得られた従来のフッ素樹脂が用いられた耐油性紙と同様に、耐油性に優れたものであることがわかる。特に、実施例３で得られた耐油性紙は、耐油性層にワックスが含有されているので、耐油性に優れるとともに、撥水性にも優れたものであることがわかる。
【００６０】
【発明の効果】
本発明の耐油性紙は、耐油性に優れているので、従来のフッ素樹脂エマルジョンが使用された包装紙と代替品として好適に使用しうるものである。特に、耐油性層にワックスが含有されている本発明の耐油性紙は、撥水性にも優れたものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to oil-resistant paper and a method for producing the same. More specifically, it is preferably used for wrapping paper for chocolate, snacks, etc., paper boxes and paper bags for french fries, fried chicken, donut, crackers, cakes, etc., wrapping paper for side dishes such as paper cards, hamburgers, top plastics, etc. Oil-resistant paper and a method for producing the same.
[0002]
[Prior art]
Generally, wrapping paper having oil resistance has a wrapping paper in which an internal sizing agent containing a fluororesin emulsion as a main component is fixed inside a paper substrate, and a coating containing a fluororesin emulsion as a main component as an external sizing agent. Packaging paper or the like in which an agent is applied to the paper surface with a coater is used.
[0003]
However, the use of a fluororesin emulsion for food packaging is questionable in terms of environmental pollution and accumulation in the human body, and in recent years, there is a tendency to avoid using such a fluororesin emulsion in recent years.
[0004]
As an alternative to the wrapping paper using the fluororesin emulsion, a polyethylene laminated paper, a wrapping paper coated with a polyvinylidene chloride emulsion, or the like is used.
[0005]
However, polyethylene laminated paper is not preferable as oil-resistant paper because of its oil permeability. In addition, it is preferable to avoid using wrapping paper coated with polyvinylidene chloride emulsion because harmful gases such as dioxin may be generated during incineration.
[0006]
In addition, parchment paper, glassine paper, wax-impregnated paper, and the like are used as wrapping paper, but all of these have low oil resistance and cannot withstand practical use.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the related art, and has as its object to provide an oil-resistant paper excellent in oil resistance, which can be substituted for a wrapping paper using a conventional fluororesin emulsion. Another object of the present invention is to provide an oil-resistant paper having excellent water repellency.
[0008]
[Means for Solving the Problems]
The present invention
(1) oil-resistant paper in which an oil-resistant layer containing an acrylic resin, a styrene-butadiene copolymer and a polyester is formed on the surface of a paper base material;
(2) (A) Acrylic resin emulsion, styrene / butadiene copolymer latex, and polyester are mixed,
(B) After applying the obtained oil-resistant layer forming resin composition to the surface of a paper substrate,
(C) a method for producing an oil-resistant paper, characterized by drying the paper base material, and (3) emulsion polymerization of (A) a raw monomer of an acrylic resin in the presence of a styrene / butadiene copolymer latex. Let
(B) A resin emulsion containing resin particles having the obtained acrylic resin as a core and a styrene-butadiene copolymer as a shell is mixed with polyester,
(C) After applying the obtained oil-resistant layer forming resin composition to the surface of a paper substrate,
(D) A method for producing oil-resistant paper, characterized by drying the paper base.
[0009]
In addition, "(meth) acrylic acid" in this specification means acrylic acid and / or methacrylic acid. The same applies to the ester.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The oil-resistant paper of the present invention is one in which an oil-resistant layer containing an acrylic resin, a styrene-butadiene copolymer and a polyester is formed on the surface of a paper substrate.
[0011]
The acrylic resin can be obtained, for example, by copolymerizing a raw material monomer containing methyl methacrylate, butyl acrylate and styrene as main components. In this case, from the viewpoint of enhancing the water repellency and oil resistance of the oil-resistant paper, the content of methyl methacrylate in the raw material monomer is preferably 45 to 85% by weight, more preferably 55 to 75% by weight, and the content of butyl acrylate is The amount is preferably 3 to 30% by weight, more preferably 5 to 20% by weight, and the styrene content is preferably 5 to 50% by weight, more preferably 10 to 40% by weight.
[0012]
The raw material monomer may contain another copolymerizable monomer as long as the object of the present invention is not hindered.
[0013]
Other copolymerizable monomers include, for example, (meth) acrylic acid; ethyl (meth) acrylate, propyl (meth) acrylate, butyl methacrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (Meth) acrylates such as (meth) acrylate; hydroxy-containing (meth) acrylates such as hydroxyethyl (meth) acrylate and ethylene glycol di (meth) acrylate; epoxy-containing (meth) acrylates such as glycidyl (meth) acrylate Styrene; alkylstyrene such as methylstyrene; ethylenically unsaturated carboxylic acids such as itaconic acid, maleic acid, fumaric acid, crotonic acid; aromatic mono- and divinyl compounds such as chlorostyrene and divinylbenzene; Vinyl compounds containing nitrile groups such as lonitrile; ethylenic amides such as (meth) acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate; alkylstyrenes such as α-methylstyrene; Is not limited only to such an example. These monomers may be used alone or in combination of two or more.
[0014]
Acrylic resin
(I) A method of emulsion-polymerizing a raw material monomer of an acrylic resin (hereinafter, referred to as Production Method I), or (II) A method of emulsion-polymerizing a raw material monomer of an acrylic resin in the presence of a styrene-butadiene copolymer latex ( Hereinafter, it is referred to as production method II)
Can be manufactured by
[0015]
In the production method I, an acrylic resin emulsion is obtained by emulsion-polymerizing the raw material monomers. The acrylic resin emulsion can be obtained by a conventional method, for example, by subjecting a raw material monomer to emulsion polymerization in water in the presence of an emulsifier. The content of the acrylic resin in the acrylic resin emulsion is not particularly limited, but is usually preferably from 35 to 55% by weight. The obtained acrylic resin emulsion can be uniformly mixed with a styrene / butadiene copolymer described below.
[0016]
In the production method II, resin particles having an acrylic resin as a core and a styrene / butadiene copolymer as a shell can be obtained by emulsion polymerization of a raw material monomer in the presence of a styrene / butadiene copolymer latex. Since such a resin particle contains an acrylic resin and a styrene-butadiene copolymer, it can be used as an integrated resin of the acrylic resin and the styrene-butadiene copolymer. The resin particles can be obtained by a conventional method, for example, by emulsion-polymerizing a raw material monomer in the presence of a styrene / butadiene copolymer latex. The diameter of the generated resin particles is usually about 1 to 3 μm.
[0017]
The ratio of styrene and butadiene (styrene / butadiene: weight ratio) in the styrene / butadiene copolymer is from 10/90 to 50/50, preferably from 20/80, from the viewpoint of the flexibility and oil resistance of the oil-resistant layer. It is desirable that the ratio be 40/60, more preferably 30/70 to 40/60. Also, the number average molecular weight of the styrene-butadiene copolymer is desirably 300,000 to 1,500,000, preferably 400,000 to 800,000.
[0018]
As the styrene-butadiene copolymer, using a styrene-butadiene copolymer latex, when using the acrylic resin obtained by the manufacturing method I, from the viewpoint that it can be uniformly mixed with the acrylic resin, When the production method II is adopted, it is preferable from the viewpoint that the raw material monomer can be uniformly mixed. In this case, the content of the styrene / butadiene copolymer in the styrene / butadiene copolymer latex is preferably about 40 to 50% by weight.
[0019]
When using a styrene-butadiene copolymer latex, the amount of the styrene-butadiene copolymer latex may be adjusted so that the weight ratio of the acrylic resin and the styrene-butadiene copolymer becomes a value described later. preferable.
[0020]
The weight ratio of the acrylic resin to the styrene / butadiene copolymer (acrylic resin / styrene / butadiene copolymer) is from the viewpoint of improving oil resistance and mechanical strength and from the viewpoint of improving the oil resistance of the oil resistant layer. , 50/50 to 90/10, preferably 55/45 to 70/30.
[0021]
As the polyester, it is preferable to use a water-soluble polyester from the viewpoint that it can be uniformly mixed with the acrylic resin and the styrene-butadiene copolymer.
[0022]
Preferred examples of the water-soluble polyester include sulfopolyester. Sulfopolyester is obtained by dehydrating and condensing ethylene glycol with sodium isophthalate sulfonate. The content of sodium isophthalate sulfonate in one molecule of the sulfopolyester is preferably 1 to 8 mol, and more preferably 2 to 5 mol, from the viewpoint of oil resistance and water repellency.
[0023]
In addition, other than sodium isophthalate sulfonate as an acid component, terephthalic acid, orthophthalic acid, isophthalic sulfonic acid, succinic acid, adipic acid, sebacic acid, dodecane An acid, dimer acid, paraoxybenzoic acid, azelaic acid, trimellitic acid and the like may be contained.
[0024]
As the alcohol component, other than ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol may be used as long as the object of the present invention is not impaired. , Polyethylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, pentaerythritol and the like. These polyhydric alcohols may be used alone or as a mixture of two or more. Among these, ethylene glycol, propylene glycol and 1,6-hexanediol are preferred.
[0025]
The water-soluble polyester can be used as an aqueous polyester solution dissolved in water. Such a polyester solution has the advantage that it can be uniformly mixed with the acrylic resin emulsion and the styrene / butadiene copolymer latex. The concentration of the water-soluble polyester in the aqueous polyester solution is not particularly limited, but is preferably about 30 to 35% by weight in consideration of handleability and the like.
[0026]
The number average molecular weight of the polyester is from 5,000 to 12,000, preferably from 5,500 to 11, from the viewpoint of improving the oil resistance of the formed oil-resistant layer and improving the coating properties on the paper substrate. 2,000 is desirable.
[0027]
The amount of the polyester is 1 to 30 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the total amount of the acrylic resin and the styrene-butadiene copolymer, from the viewpoint of increasing the oil resistance of the formed oil-resistant layer. It is desirably 15 parts by weight.
[0028]
When an acrylic resin emulsion is produced by the manufacturing method I, the acrylic resin emulsion, a styrene-butadiene copolymer latex, and a polyester are mixed to obtain an oil-resistant layer-forming resin composition. be able to.
[0029]
When a resin emulsion containing resin particles having an acrylic resin as a core and a styrene-butadiene copolymer as a shell is produced by the production method II, the resin emulsion is mixed with polyester to obtain oil resistance. A layer-forming resin composition can be obtained.
[0030]
In the present invention, from the viewpoint of improving the water repellency of the oil-resistant layer, it is preferable that the resin composition for forming the oil-resistant layer contains a wax.
[0031]
Representative examples of the wax include Fischer-Tropsch wax, paraffin wax, microcrystalline wax, montan wax, polyethylene wax, and the like. These waxes can be used alone or as a mixture of two or more. Among these waxes, Fischer-Tropsch wax having a softening point of 106 ° C. or more is preferably used because it hardly bleeds from the formed oil-resistant layer and reduces the slipperiness of the oil-resistant layer. It is.
[0032]
The wax can be used as it is, but is used as an aqueous solution or a suspension in water so that it can be uniformly mixed with the acrylic resin, the styrene-butadiene copolymer, and the polyester. Is preferred.
[0033]
From the viewpoint of increasing the water repellency of the oil-resistant layer and preventing the slipperiness of the oil-resistant layer from becoming too high, the amount of the wax is 100 parts by weight in total of the acrylic resin, the styrene-butadiene copolymer and the polyester. On the other hand, the amount is preferably 0.5 to 5 parts by weight, more preferably 0.75 to 3 parts by weight.
[0034]
The oil-resistant layer can be formed by applying the resin composition for an oil-resistant layer to the surface of a paper base and then drying the paper base.
[0035]
Examples of the paper substrate include kraft paper, high-quality paper, medium-quality paper, coated paper, coated cardboard, paperboard, and the like, but the present invention is not limited to only these examples. Among these, a paper substrate having a dense and smooth surface is preferred from the viewpoint of increasing the adhesive strength between the oil-resistant layer and the paper substrate.
[0036]
Examples of a method of applying the resin composition for an oil-resistant layer to a paper substrate include size press coating, roll coating, air knife coating, blade coating, gravure coating, and the like, but the present invention is limited to only such examples. Not something. When applying the resin composition for an oil-resistant layer to a paper substrate, the resin composition for an oil-resistant layer may be appropriately diluted with a solvent such as water in consideration of coatability and the like.
[0037]
The oil-resistant layer may be formed on only one side of the paper substrate, or may be formed on both sides. Whether the oil-resistant layer is formed on one side or both sides of the paper base may be appropriately determined according to the use of the paper base. Further, the oil-resistant layer may be formed on the entire surface of one or both sides of the paper substrate, or may be formed partially, but from the viewpoint of increasing the oil resistance of the obtained oil-resistant paper, Is preferably formed on the entire surface on one side or both sides.
[0038]
The amount of coating (the amount after drying) of the resin composition for an oil-resistant layer varies depending on the use of the paper substrate and the like, and cannot be unconditionally determined. However, from the viewpoint of suppressing the generation of pinholes, the coating amount is usually preferably 8 g / m ² or more, and more preferably 12 g / m ² or more. Since improvement in oil resistance cannot be expected, it is desirable to be 20 g / m ² or less, preferably 15 g / m ² or less.
[0039]
After forming the oil-resistant layer on the paper substrate, it is preferable to heat the oil-resistant layer so as to fix the formed oil-resistant layer to the paper substrate and to improve the oil resistance. Such heating can be performed using, for example, hot air. Usually, it is preferable to adjust the heating temperature so that the temperature of the paper substrate is 100 to 140 ° C. The heating is preferably performed until water is removed from the resin composition for an oil-resistant layer and a film is formed.
[0040]
The thus obtained oil-resistant paper of the present invention is excellent in oil resistance, has heat sealing properties, and has the advantage that it can be bonded using a commercially available emulsion adhesive.
[0041]
【Example】
Next, the present invention will be described in more detail based on examples, but the present invention is not limited to only these examples.
[0042]
Example 1
60 parts by weight of an acrylic resin emulsion (resin solids content: 50% by weight) obtained by copolymerizing a raw material monomer comprising 70 parts by weight of methyl methacrylate, 10 parts by weight of butyl acrylate and 20 parts by weight of styrene, and styrene butadiene After mixing 40 parts by weight of a copolymer latex emulsion [styrene / butadiene (weight ratio) = 35/65, styrene / butadiene copolymer content: 40% by weight], an acrylic resin and styrene / butadiene copolymer were mixed. For the oil resistant layer, the sulfopolyester (number average molecular weight: 3,000) was mixed so that the amount (resin solid content) was 15 parts by weight with respect to 100 parts by weight of the total amount (solid content of resin). A resin composition was prepared.
[0043]
Next, the obtained resin composition for an oil-resistant layer was dried at 8 g / m ² , 10 g / m ² , 12 g / m ² , 15 g / m ² or 20 g / m ² using a Meyer bar. After applying to the glossy surface of a single-gloss bleached kraft paper having a basis weight of 70 g / m ² so as to be ² , drying was performed for 60 seconds by a blow dryer adjusted to 130 ° C.
[0044]
After leaving the obtained oil-resistant paper having the oil-resistant layer in an atmosphere under standard conditions (temperature: 20 ± 2 ° C., relative humidity: 65 ± 2%) in accordance with the provisions of JIS P-8111 for 4 hours, Oil resistance and water repellency were examined based on the following methods. Table 1 shows the results.
[0045]
(Oil resistance)
The test is performed according to the test method described in TAPPI-UM-5557 (kit test method). A test solution specified in TAPPI-UM-5557 is gently dropped on the surface of the oil-resistant paper, and after 10 seconds, the oil resistance is evaluated. In TAPPI-UM-5557, the oil resistance is classified into grades from grade 1 to grade 16, and a grade of grade 6 or higher is judged to be a pass.
[0046]
(Water repellency)
The water repellency is measured according to JIS P-8137 (test method for water repellency of paper and paperboard). The degree of water repellency is evaluated on a scale of R1 to R10, and an evaluation of R6 or more is judged as having water repellency.
[0047]
Example 2
40 parts by weight of styrene / butadiene copolymer latex [styrene / butadiene (weight ratio) = 35/65, styrene / butadiene copolymer content: 40% by weight], 42 parts by weight of methyl methacrylate, 6 parts by weight of butyl acrylate And 5 parts by weight of polyoxyethylene nonylphenyl ether as an emulsifier, and 1 part by weight of ammonium persulfate as a polymerization initiator, and heated to 75 ° C. with stirring to carry out emulsion polymerization. As a result, a resin emulsion containing resin particles having an acrylic resin as a core and a styrene / butadiene copolymer as a shell was obtained.
[0048]
Next, the obtained resin emulsion and a sulfopolyester (number average molecular weight: 3,000) were mixed with 100 parts by weight of the resin solid content in the resin emulsion so that the amount of the sulfopolyester (resin solid content) was 15 parts by weight. To prepare a resin composition for an oil-resistant layer.
[0049]
Next, using the obtained resin composition for an oil-resistant layer, an oil-resistant paper was produced in the same manner as in Example 1, and oil resistance and water repellency were examined. Table 1 shows the results.
[0050]
Example 3
In Example 1, a Fischer-Tropsch wax emulsion (softening point of wax: 106 ° C., wax content) was added to 100 parts by weight of the total amount of the acrylic resin, sulfopolyester, and styrene-butadiene copolymer (resin solid content). Oil-resistant paper was produced in the same manner as in Example 1 except that 3 parts by weight of the solid content was added.
[0051]
Next, the physical properties of the obtained oil-resistant paper were measured in the same manner as in Example 1. Table 1 shows the results.
[0052]
Comparative Example 1
A resin composition for an oil-resistant layer was prepared in the same manner as in Example 3, except that the sulfopolyester was not used.
[0053]
Next, an oil-resistant paper was manufactured in the same manner as in Example 1 using the obtained resin composition for an oil-resistant layer, and the physical properties of the oil-resistant paper were measured in the same manner as in Example 1. Table 1 shows the results.
[0054]
Comparative Example 2
Per 100 parts by weight of the resin solid content of 30% by weight aqueous sulfopolyester solution (number average molecular weight: 3,000), the solid content of Fischer-Tropsch wax emulsion (wax softening point: 106 ° C., wax content: 50% by weight) Were mixed at a ratio of 5 parts by weight to prepare a resin composition for an oil-resistant layer.
[0055]
Next, an oil-resistant paper was manufactured in the same manner as in Example 1 using the obtained resin composition for an oil-resistant layer, and the physical properties of the oil-resistant paper were measured in the same manner as in Example 1. Table 1 shows the results.
[0056]
REFERENCE EXAMPLE In Example 1, a fluorine-based oil-resistant coating agent [Asahi Glass AG-530, trade name: Asahigard AG-530] was used instead of the resin composition for the oil-resistant layer, and the oil-resistant layer was coated after drying. An oil-resistant paper was manufactured in the same manner as in Example 1, except that the coating amount was 6 g / m ² .
[0057]
Next, an oil-resistant paper was manufactured in the same manner as in Example 1 using the obtained resin composition for an oil-resistant layer, and the physical properties of the oil-resistant paper were measured in the same manner as in Example 1. Table 1 shows the results.
[0058]
[Table 1]

[0059]
From the results shown in Table 1, all of the oil-resistant papers obtained in Examples 1 to 3 have the same oil resistance as the oil-resistant paper using the conventional fluororesin obtained in Reference Example. It turns out that it is excellent. In particular, it can be seen that the oil-resistant paper obtained in Example 3 has excellent oil resistance and water repellency because the oil-resistant layer contains wax.
[0060]
【The invention's effect】
Since the oil-resistant paper of the present invention has excellent oil resistance, it can be suitably used as a substitute for packaging paper using a conventional fluororesin emulsion. In particular, the oil-resistant paper of the present invention in which the oil-resistant layer contains a wax has excellent water repellency.

Claims (6)

An oil-resistant paper having an oil-resistant layer containing an acrylic resin, a styrene-butadiene copolymer and a polyester formed on the surface of a paper substrate. The oil resistant paper according to claim 1, wherein the weight ratio of the acrylic resin to the styrene / butadiene copolymer (acrylic resin / styrene / butadiene copolymer) is 50/50 to 90/10. 3. The oil-resistant paper according to claim 1, wherein the polyester is a sulfopolyester. The oil-resistant paper according to any one of claims 1 to 3, wherein the oil-resistant layer contains a wax. (A) Acrylic resin emulsion, styrene / butadiene copolymer latex, and polyester are mixed,
(B) After applying the obtained oil-resistant layer forming resin composition to the surface of a paper substrate,
(C) A method for producing oil-resistant paper, characterized by drying the paper substrate. (A) Emulsion polymerization of a raw material monomer of an acrylic resin in the presence of a styrene / butadiene copolymer latex,
(B) A resin emulsion containing resin particles having the obtained acrylic resin as a core and a styrene-butadiene copolymer as a shell is mixed with polyester,
(C) After applying the obtained oil-resistant layer forming resin composition to the surface of a paper substrate,
(D) A method for producing oil-resistant paper, characterized by drying the paper substrate.