JP3464734B2 - Resin composition for paper impregnation - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper impregnating resin composition for obtaining a transparent paper having excellent bleed resistance, solvent resistance and transparency. is there. 2. Description of the Related Art In accordance with the market trend of upscaling and differentiation, the need for upscaling of paper is very high, and many varieties are being developed. Above all, there is a strong demand for transparent paper having a transparent texture, and development has been promoted conventionally. In many cases, paper clarification is achieved by impregnating the paper with natural or artificial polymers. [0003] However, as the use of the transparent paper is rapidly expanding, it is required to improve the performance other than the transparency of the paper, and particularly the bleed resistance and the solvent resistance are required. [0004] In the case of conventional transparent paper, for example, when the transparent paper is exposed to high temperatures during storage in the summer, the impregnated polymer becomes low in viscosity, and the polymer moves to the one in contact with the transparent paper. Or (this phenomenon is called bleed)
When a solvent such as alcohol is brought into contact with the transparent paper, the impregnated polymer dissolves and separates from the paper, resulting in a problem that the transparency of the portion is impaired. [0005] Various studies have been made to solve such problems, but satisfactory transparent papers have not yet been obtained. For example, there has been proposed a method of improving bleed resistance by using an acrylic resin having a high second-order transition temperature as a polymer, and improving solvent resistance by further increasing the molecular weight. However, when the resin is impregnated with an acrylic resin having a high secondary transition temperature and a high molecular weight, there is a problem that the transparency of the paper is reduced. It is an object of the present invention to provide a paper impregnating resin composition for providing a transparent paper having both transparency, bleed resistance and solvent resistance. Means for Solving the Problems As a result of intensive studies on the paper impregnating resin, the present inventors have achieved the above object by using a composition comprising a specific crosslinkable vinyl polymer. I found something. That is, the paper-impregnating resin composition of the present invention comprises a hydroxyl-containing vinyl monomer unit (a) in an amount of 0.3 to 10% by weight and a carboxyl-containing vinyl monomer unit (a). b) 0.01 to 5% by weight, other copolymerizable vinyl monomer units (c) 85 to 99.6
A vinyl polymer [I] having a secondary transition temperature of 0 to 90 ° C. and a weight average molecular weight in the range of 1,500 to 5,000, and an organic isocyanate derivative having two or more isocyanate groups. [II] An organic solvent mixture [III] containing at least 80% by weight of an organic solvent having a boiling point of 80 to 220 ° C. at normal pressure, wherein 1 mol of hydroxyl groups in [I] and [II] The isocyanate group is 0.1 to 2 mol, and the content of [III] is 40 to 150 parts by weight based on 100 parts by weight of [I]. BEST MODE FOR CARRYING OUT THE INVENTION The vinyl polymer [I] used in the resin composition for paper impregnation of the present invention comprises the following monomers (a):
It is obtained by copolymerizing (b) and (c) at a specific ratio. The hydroxyl group-containing vinyl monomer (a) used in the vinyl polymer [I] of the present invention comprises:
A component for imparting reactivity with an isocyanate group to the vinyl polymer [I], and is used in the range of 0.3 to 10% by weight. When the component (a) is less than 0.3% by weight,
Since the crosslinking reaction between the hydroxyl group and the isocyanate group does not proceed sufficiently, the bleeding resistance of the obtained transparent paper,
If the solvent resistance is insufficient, and if it exceeds 10% by weight, the reaction between the hydroxyl group and the isocyanate group proceeds too quickly.
The resin composition tends to thicken and gel during the paper impregnation step, which is not preferable. More preferably, it is in the range of 0.5 to 4% by weight. The component (a) of the present invention includes, for example, 2
-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2- Ring-opening adducts of ε-caprolactone or γ-butyrolactone to hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate (for example, Plaxel FM) , Praxel FA, manufactured by Daicel Chemical Co., Ltd.)
Hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferred. These can be used alone or in combination of two or more as necessary. The carboxyl group-containing vinyl monomer (b) used in the vinyl polymer [I] of the present invention comprises:
(A) A component for appropriately controlling the reactivity between the component and the isocyanate group, and is used in the range of 0.01 to 5% by weight. When the component (b) is less than 0.01% by weight,
Since the cross-linking reaction between the component (a) and the isocyanate group does not proceed sufficiently, the bleeding resistance and solvent resistance of the obtained transparentized paper tend to be insufficient. Since the reaction proceeds too quickly, the resin composition tends to thicken and gel during the process of impregnating the paper. More preferably, it is in the range of 0.1 to 2% by weight. The component (b) of the present invention includes, for example, monobasic carboxylic acids such as methacrylic acid, acrylic acid and crotonic acid; dibasic carboxylic acids such as itaconic acid, maleic acid and fumaric acid; and maleic acid. Monomethyl acid, β-
Examples thereof include partial esters of dibasic carboxylic acids such as methacryloxyethyl hexahydrophthalate, and methacrylic acid and acrylic acid are particularly preferable. These can be used alone or in combination of two or more as necessary. The other copolymerizable vinyl monomer (c) used in the vinyl polymer [I] of the present invention is not particularly limited, and has at least one polymerizable vinyl group. It can be arbitrarily selected from those possessed according to the purpose, and is used in the range of 85 to 99.69% by weight. When the component (c) is less than 85% by weight,
During the process of impregnating paper, the resin composition tends to thicken and gel, and if it exceeds 99.69% by weight, the bleeding resistance and solvent resistance of the resulting transparent paper tend to be insufficient. As the component (c) of the present invention, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate ,
C1-C1 such as cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate
(Meth) acrylic acid alkyl esters having an alkyl group of 18; aromatic vinyl compounds such as styrene, α-methylstyrene, paramethylstyrene, and benzyl (meth) acrylate; alkylamino (dimethylaminoethyl (meth) acrylate); (Meth) acrylates, dimethylaminoethyl (meth) acrylate methyl chloride salt, allyl (meth) acrylate, trimethylolpropane (meth) acrylate, glycidyl (meth) acrylate, vinyl acetate, vinyl propionate, (meth)
Known polymerizable vinyl monomers such as acrylonitrile are exemplified. These can be used alone or in combination of two or more as necessary. The vinyl polymer [I] of the present invention can be produced by a known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, and a suspension polymerization method. Taking into account the ease of the preparation process for the phenol, it is preferable to produce the solution by a solution polymerization method. For example, the vinyl polymer [I] of the present invention is prepared by adding a vinyl monomer mixture comprising the above (a) to (c) in the presence of a radical polymerization initiator.
It can be obtained by reacting at a reaction temperature of 0 to 250 ° C, preferably 120 to 170 ° C for 6 to 12 hours. As the polymerization initiator, for example, conventionally known ones such as an azo initiator such as azobisisobutyronitotyl and a peroxide initiator such as benzoyl peroxide can be arbitrarily selected and used. . Further, if necessary, a chain transfer agent such as n-dodecyl mercaptan or α-methylstyrene dimer can be used. The vinyl polymer [I] obtained as described above has a secondary transition temperature (hereinafter referred to as Tg) of 0.
９０90 ° C., the weight average molecular weight must be in the range of 1,500-5,000. This is because when the Tg of the vinyl polymer [I] of the present invention is less than 0 ° C., the bleeding resistance of the obtained transparent paper tends to be insufficient, and when it exceeds 90 ° C., the transparency of the paper becomes insufficient. This is because there is a tendency to do so.
More preferably, it is in the range of 20 to 70 ° C. The vinyl polymer [I] of the present invention has a weight average molecular weight of 1,50.
If it is less than 0, the bleeding resistance of the obtained transparent paper tends to be insufficient, and if it exceeds 5,000, the transparency of the paper tends to be insufficient. More preferably 2,5
The range is from 00 to 3,500. The organic isocyanate derivative [II] used in the paper impregnating resin composition of the present invention has two isocyanate groups.
And a component for improving the bleeding resistance and solvent resistance of the transparentized paper by the crosslinking reaction of the isocyanate group with the hydroxyl group in the vinyl polymer [I]. The amount of the isocyanate group in the component [II] is 0.1 to 1 mol of the hydroxyl group in the component [I].
An amount ranging from 1 to 2 moles is used. If the amount of the isocyanate group is less than 0.1 mol, the crosslinking reaction between the hydroxyl group and the isocyanate group becomes insufficient, so that the effect of improving the bleed resistance and the solvent resistance of the transparent paper cannot be obtained. When the amount of isocyanate groups exceeds 2 mol, unreacted isocyanate groups remaining on the transparentized paper tend to reduce the bleeding resistance of the transparentized paper. More preferably, the amount of the isocyanate group in the component [II] to be in the range of 0.5 to 1.3 mol per 1 mol of the hydroxyl group in the component [I] is used. The component [II] of the present invention may have a free isocyanate group or may have a blocked isocyanate group. As the component [II] of the present invention, for example, aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6- Cycloaliphatic diisocyanates such as diisocyanate, 4,4′-methylenebiscyclohexyl isocyanate, 1,3-diisocyanatemethyl-cyclohexane, aromatic diisocyanates such as tolylene diisocyanate and xylene diisocyanate, Adducts with polyhydric alcohols or water, polymers of the above-mentioned diisocyanates, isocyanate / buret bodies, etc., and aliphatic such as hexamethylene diisocyanate. Isocyanates are particularly preferred. These can be used alone or in combination of two or more as necessary. The organic solvent mixture [III] of the present invention contains at least 80% by weight of an organic solvent having a boiling point at normal pressure (hereinafter, referred to as boiling point) of 80 to 220 ° C. The content in the paper impregnating resin composition of the present invention is 40 to 150 with respect to 100 parts by weight of the component [I].
It is in the range of parts by weight. When the organic solvent having a boiling point of less than 80 ° C. exceeds 20% by weight in the component [III], the transparency of the obtained transparent paper tends to decrease, and the organic solvent having a boiling point of more than 220 ° C. If it exceeds 20% by weight, the drying property after impregnating the paper with the resin composition tends to decrease, and the bleeding resistance of the obtained transparent paper tends to decrease. More preferably, the component [III] contains 85% by weight or more of an organic solvent having a boiling point of 120 to 210 ° C. When the boiling point of the component [III] cannot be measured as a constant temperature, the boiling point can be regarded as a temperature between the 5% distillation temperature and the 95% distillation temperature of the component [III]. When the content of the component [III] is less than 40 parts by weight based on 100 parts by weight of the component [I],
Since the viscosity of the resin composition for paper impregnation becomes too high, the impregnating property into the paper fibers of the resin composition tends to decrease, and the transparency of the resulting transparent paper tends to decrease. If the amount exceeds 150 parts by weight, the resin concentration of the resin composition for paper impregnation becomes too low, so that the amount of the resin impregnated in the paper becomes insufficient, and the transparency of the obtained transparent paper tends to decrease. More preferably, it is in the range of 50 to 110 parts by weight. The component [III] of the present invention includes, for example,
Aromatic hydrocarbons such as xylene and Supersol 1500 (Mitsubishi Petroleum), mineral spirits, LAUS
(E.g., shell petroleum); esters such as n-butyl acetate; ketones such as methyl amyl ketone; and aromatic hydrocarbons are preferable. The component [III] can be used as a solvent when the component [I] is obtained by solution polymerization. The paper impregnating resin composition of the present invention may further comprise an antifoaming agent, if necessary, in order to exhibit higher performance.
It is possible to add a pigment dispersant, a plasticizer, and the like. As a method for obtaining a transparent paper using the paper impregnating resin composition of the present invention, a conventionally known method may be used.
Generally, after the paper impregnating resin composition of the present invention is applied to paper using a roll coater, the transparent paper is dried by blowing hot air of about 50 to 150 ° C. for about 1 minute. Obtainable. The present invention will be specifically described below with reference to examples. All parts and percentages in the examples are by weight. Physical properties of vinyl polymer [I] Weight average molecular weight: measured by GPC method (polystyrene conversion) Secondary transition temperature (Tg): measured value by DSC method (° C) Characteristic pot life of resin composition for paper impregnation : The viscosity immediately after the preparation of the resin composition for paper impregnation (measured at 25 ° C. by a B-type viscometer, the same applies hereinafter) is defined as (A), and the prepared resin composition for paper impregnation at 25 ° C. is 5
The viscosity of the material left for a long time is (b), (b) / (b)
The pot life is determined by the value of. The pot life is determined based on the following criteria. Very good: (b) / (b) ≦ 1.05 Good: 1.05 <(b) / (b) ≦ 1.2 Poor: 1.2 <(b) / (b) Transparency Characteristic transparency of modified paper: The light transmittance of the resin-unimpregnated paper is [X], the light transmittance of the resin-impregnated paper is [Y], and the value of [Y] / [X] is the transparency. In addition, the measurement of the light transmittance is performed by AST
This is based on MD1003. The transparency is determined based on the following criteria. Very good: 1.8 <(transparency) Good: 1.6 <(transparency) ≦ 1.8 Poor: (transparency) ≦ 1.6 Solvent resistance: resin-impregnated paper Is immersed in toluene at 25 ° C. for 5 seconds, and dried at room temperature for 30 minutes. The light transmittance is defined as [Z], and the solvent resistance is determined based on the value of [Y] / [Z]. The solvent resistance is determined according to the following criteria. Very good: [Y] / [Z] <1.2 Good: 1.2 ≦ [Y] / [Z] <1.4 Poor: 1.4 ≦ [Y] / [Z] Bleed resistance Properties: Resin-unimpregnated paper and resin-impregnated paper are superimposed, left under a load of 300 g / cm ² for 3 hours in an atmosphere of 60 ° C., then separated from each other, and the resin-impregnated treatment adhered to the resin-unimpregnated paper. The area of the resin-derived stain in the paper is measured to determine bleed resistance. The bleed resistance is determined according to the following criteria. Very good: The adhesion area of the stain on the resin-unimpregnated paper is 5% of the contact area between the resin-unimpregnated paper and the resin-impregnated paper.
What is less than. Good: The stain adhesion area on the resin-unimpregnated paper is
5% or more of the contact area between resin-unimpregnated paper and resin-impregnated paper2
Less than 0%. Poor: The area of the stain adhering to the resin-unimpregnated paper is
20% or more of the contact area between the resin-unimpregnated paper and the resin-impregnated paper. (1) Production Example of Vinyl Polymer Solution (I-1) Solvesso No. 150 (aromatic hydrocarbon, No. 150) was placed in a four-necked flask equipped with a cooler, a thermometer, a dropping funnel and a stirrer.
Mitsubishi Chemical 5% distillation temperature 187 ° C, 95% distillation temperature 2
(02 ° C.), 100 parts were added, and after the temperature was raised to 140 ° C., 4 parts of hydroxyethyl methacrylate (HEMA), 0.5 part of methacrylic acid (MAA), and
A) 20 parts, isobutyl methacrylate (i-BMA)
A mixed solution of 35.5 parts, 20 parts of styrene (St), 20 parts of ethyl acrylate (EA), and 3 parts of azobisisobutyronitrile was added dropwise over 4 hours. Thereafter, 3 parts of azobisisobutyronitrile was gradually added to complete the polymerization, and a vinyl polymer solution (I-1) was obtained. The secondary transition temperature (Tg) of the obtained vinyl polymer was 40 ° C., and the weight average molecular weight was 4,000. (2) Vinyl polymer solution (I-2)
Production Example of (I-20) By the same method as in the production example of the vinyl polymer solution (I-1), polymerization was performed with a polymerization composition as shown in Table 1, and the vinyl polymer solution (I-2) was obtained. ) To (I-20). Table 2 shows the physical properties of the obtained vinyl polymer. [Table 1] Explanation of symbols HEMA: 2-hydroxyethyl methacrylate 4HBA: 4-hydroxybutyl acrylate MAA: methacrylic acid AA: acrylic acid MMA: methyl methacrylate St: styrene t-BMA: t-butyl methacrylate EA: ethyl acrylate EHA: Ethylhexyl acrylate: 2-mol of ε-caprolactone to 2-hydroxyethyl methacrylate: β-methacryloxyethyl hexahydrophthalate: The content (% by weight) of an organic solvent having a boiling point in the range of 80 to 220 ° C. Description MIBK (methyl isobutyl ketone): Boiling point 115.8
° C Butyl acetate: Boiling point 127 ° C Toluene: Boiling point 111.1 ° C Xylene: Boiling point 127 to 159 ° C Acetone: Boiling point 56.2 ° C Ethyl acetate: Boiling point 77.6 ° C Superzol # 1500 (aromatic hydrocarbon, manufactured by Mitsubishi Petroleum Corporation) ): 5% distillation temperature 161 ° C., 95% distillation temperature 164
° C LAUS (aliphatic hydrocarbon, manufactured by Shell Chemical): 5% distillation temperature 161.5 ° C, 95% distillation temperature 186 ° C Isopar M (aliphatic hydrocarbon, manufactured by Exxon Chemical):
5% distillation temperature 210 ° C., 95% distillation temperature 248 ° C. Example 1 Hexamethylene diisocyanate was added to a vinyl polymer solution (I-1) such that isocyanate groups were 1.0 mol per 1 mol of hydroxyl groups in the polymer.
A resin composition for paper impregnation was prepared. In addition, prepare 20
After a lapse of minutes, the resin composition for paper impregnation was applied to PPC paper (My Paper, manufactured by NBS) using a bar coater #.
6 was applied in an atmosphere of 25 ° C., and after 10 seconds had passed since the application, this was treated at 130 ° C. for 1 minute using a drying oven to obtain a transparent paper. The pot life of the prepared resin composition for paper impregnation was very good, and the transparency, solvent resistance and bleed resistance of the obtained transparentized paper were also very good. Examples 2 to 12 and Comparative Examples 1 to 12 Paper impregnating resin compositions were prepared according to the compositions shown in Table 3, and transparent papers were produced in the same manner as in the examples. Table 4 shows the results of evaluating the resin composition for paper impregnation and the transparent paper in the same manner as in Example 1. [Table 3] [Table 4] The resin composition for paper impregnation of the present invention and the clarified paper obtained from the resin composition for paper impregnation of the present invention have excellent properties as shown in Examples 1 to 12. I was On the other hand, the resin compositions for paper impregnation and the clarified paper which do not satisfy the conditions specified by the present invention are Comparative Examples 1 to 1.
No satisfactory properties were exhibited as shown in FIG. As is clear from the above examples, the resin composition for paper impregnation of the present invention has a good pot life, and the transparency obtained from the resin composition for paper impregnation of the present invention is improved. Paper has excellent transparency, solvent resistance and bleed resistance, and is industrially very useful.

Continuation of the front page (56) References JP-A-53-25648 (JP, A) JP-A-52-112323 (JP, A) JP-A-57-167499 (JP, A) JP-A-58-98496 (JP) JP-A-54-50612 (JP, A) JP-A-52-128414 (JP, A) JP-A-55-80597 (JP, A) JP-B-47-35531 (JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (1)

(57) Claims 1. A hydroxyl-containing vinyl monomer unit (a) 0.3 to 10% by weight, a carboxyl-containing vinyl monomer unit (b) 0.01 to 5% by weight,
Other copolymerizable vinyl monomer units (c) 85 to 9
9.69% by weight, having a second order transition temperature of 0-90.
° C, a vinyl polymer [I] having a weight average molecular weight in the range of 1,500 to 5,000, an organic isocyanate derivative [II] having two or more isocyanate groups, and a boiling point at normal pressure of 80 to 220 ° C. An organic solvent mixture [III] containing at least 80% by weight of an organic solvent, wherein the amount of the isocyanate group in [II] is 0.1 to 2 mol per 1 mol of the hydroxyl group in [I]; ] The resin composition for paper impregnation whose content of [I] is 40-150 weight part with respect to 100 weight part.