JPH05140898A - Surface treating agent for paper - Google Patents

Abstract

PURPOSE:To obtain the subject surface treating agent consisting of a specific aqueous emulsion and a synthetic rubber based latex used at a specific ratio, low in odor, excellent in workability, water repellency, sliding resistance and low frothing property and useful for pressure sensitive paper. CONSTITUTION:The objective surface treating agent consisting of a combination of (A) an aqueous emulsion of a resin containing >=25wt.%, preferably >=40wt.% 1-12C alkyl (meth)acrylate such as butyl (meth)acrylate as an unit and (B) a synthetic rubber based latex such as styrene-butadiene based latex and containing these components at a weight ratio of component B/component A of 0.05-20, preferably 0.25-10, expressed in terms of solid content.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a surface treating agent for paper.

[0002]

2. Description of the Related Art Conventionally, an aqueous emulsion of a resin obtained by emulsion polymerization of 40 to 100% by weight of alkyl (meth) acrylate and 0 to 60% by weight of another copolymerizable monomer has been used as a surface finishing agent for paper. It is known (Japanese Patent Laid-Open No. 2-6691). A wax emulsion is also known as a surface-treating agent that imparts water repellency to paper.

[0003]

However, the conventional paper surface finishing agents have not been able to obtain satisfactory water repellency and slip resistance. An object of the present invention is to provide a paper surface-treating agent that imparts high water repellency and is excellent in slip resistance.

[0004]

Means for Solving the Problems As a result of research to achieve the above object, the present inventors have developed a paper surface-treating agent having high water repellency and suppressing slipperiness. Came to. That is, the present invention is alkyl (having 1 to 12 carbon atoms)
An aqueous emulsion (A) of a resin containing (meth) acrylate as a constituent unit in an amount of 25% by weight or more, and a synthetic rubber-based latex (B) in combination, and a solid content weight ratio (B) of (A) and (B). ) / (A) is 0.05-20.

In the present invention, the alkyl (C1-12) (meth) acrylate forming the resin component (A) includes, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, sec-butyl acrylate,
iso-butyl acrylate, tert-butyl acrylate, n
-Octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, iso-butyl methacrylate, tert
-Butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate and mixtures of one or more of these. It is desirable that at least one of n-butyl methacrylate and iso-butyl methacrylate be contained in these constituent units.

Other copolymerizable monomers may be contained as the resin component (A). Examples of the copolymerizable monomer include (meth) acrylic acid, aromatic vinyl monomers (styrene, vinyltoluene, α-methylstyrene, etc.), vinyl ester monomers (vinyl acetate, etc.), nitrile group-containing monomers (acrylonitrile, methacrylonitrile). Etc.), amide group-containing monomers (acrylamide, methacrylamide, etc.), hydroxyl group-containing monomers (hydroxyethyl acrylate, hydroxymethyl methacrylate, etc.), and mixtures of one or more of these. In the present invention, it is desirable that the resin component (A) contains 25% by weight or more, preferably 40% by weight or more of alkyl (meth) acrylate. Outside the above range, the water repellency will decrease.

In the present invention, (B) is a styrene-butadiene type, a methylmethacrylate-styrene-butadiene type, an acrylonitrile-butadiene type, a chloroprene type, an isoprene type obtained by a known polymerization method,
Examples thereof include synthetic rubber-based latexes such as vinyl chloride-based, vinylidene chloride-based, polybutadiene and mixtures of one or more of these. A styrene-butadiene latex is preferred.

In order to exhibit high water repellency and slip resistance in the present invention, the solid content weight ratio of (A) and (B) (B) /
It is essential that (A) is 0.05 to 20, preferably 0.25 to 10. When (B) / (A) is outside the above range, the water repellency is significantly reduced.

The surface treating agent for paper in the present invention is prepared by mixing (A) and (B) by any method. Further, if necessary, an inorganic pigment (C), a water-soluble pigment binder (D), a dispersant (E), and other functionalizing agent (F) can be used. Examples of (C) include mineral fillers generally used for paper coating such as clay, barium sulfate, titanium oxide, calcium carbonate, and satin white. As (D) casein, oxidized starch, phosphate esterified starch, polyvinyl alcohol, soybean protein,
Examples include natural or synthetic binders such as carboxymethyl cellulose, hydroxyethyl cellulose, styrene maleic acid resin, and polyacrylic acid. Examples of (E) include sodium polyacrylate, sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate. Examples of (F) include dyes and developers used for thermal paper, pressure-sensitive paper and the like.

In the present invention, the base paper to be surface-treated can be used irrespective of pulp, internally added sizing agent, pH at the time of paper making, paper strengthening agent, retention aid and the like. Further, the surface-treating agent of the present invention can be applied to the paper manufacturing process by a usual method. That is, the paper is coated on the surface of the paper with a coating device such as a size press coater, a gate roll coater, a calender coater, an air knife coater, and then dried to be surface-treated. When the coating amount in the present invention is 0.05 g / m ² (solid content) or more for the target paper, sufficient water repellency and slip resistance can be obtained. Here, in order to exhibit high water repellency by the surface-treating agent of the present invention, the surface-treating agent is usually applied at 1 to 60 at 50 to 200 ° C. after coating on the paper surface.
Drying may be performed for 0 sec, preferably 100 to 180 ° C. for 10 to 180 sec. If the drying is carried out at a temperature lower than the above range and / or a time shorter than the above range, good water repellency will not be exhibited.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, the copolymerization ratios in the Production Examples and Comparative Examples represent weight ratios. Production Example 1 40 g of 10% oxidized starch aqueous solution, 40 g of 8: 2 copolymer emulsion of n-butyl methacrylate and iso-butyl methacrylate (solid content 45%), and styrene-butadiene-acrylic acid (copolymerization ratio 58:39 : 3, Tg = 23 ° C., solid content 45%) and 40 g of a copolymer latex were blended at room temperature to prepare a surface-treating agent. Next, a bar coater (No. 12) was used to apply this surface-treating agent to one side of commercially available high-quality paper, which was dried at 150 ° C for 2 minutes and then allowed to cool at room temperature to produce surface-treated paper [1]. did. Production Example 2 2: 7: 1 copolymer emulsion of n-butyl methacrylate, iso-butyl methacrylate and styrene (solid content 45
%) 20 g and styrene-butadiene-methacrylic acid (copolymerization ratio 37: 49: 3, Tg = 23 ° C., solid content 45%) copolymer latex 6
Using a mixture with 0 g as a surface treatment agent, the drying temperature is 120
Surface treated paper by the same method as Production Example 1 except that
[2] was produced. Production Example 3 60 g of a 5: 4: 1 copolymer emulsion of n-butyl methacrylate, iso-butyl methacrylate and lauryl methacrylate (solid content 45%) and styrene-butadiene-acrylic acid (copolymerization ratio 58: 39: 3, Using a mixture with 20 g of copolymer latex with Tg = 23 ° C. and a solid content of 45%) as a surface-treating agent,
A surface-treated paper [3] was produced in the same manner as in Production Example 1 except that it was dried at 0 ° C for 10 seconds. Production Example 4 To 100 g of clay (containing 0.5 g of a polycarboxylic acid type polymer activator as a dispersant), 40 g of a 10% aqueous solution of oxidized starch heated to 60 ° C. was added and cooled to room temperature. Next, 13 g of 3: 4: 3 copolymer emulsion of n-butyl methacrylate, iso-butyl methacrylate and 2-ethylhexyl acrylate (solid content 45%) and methyl methacrylate-butadiene-acrylic acid (copolymerization ratio 58:39: (3, Tg = 23 ℃, solid content 45%)
13 g of the copolymer latex of was mixed at room temperature to prepare a surface treating agent. Next, using this surface treatment agent, the drying time
A surface-treated paper [4] was produced in the same manner as in Production Example 1 except that the time was 1 minute.

Examples 1 to 4 (Evaluation of water repellency) The surface-treated papers [1] to [4] were fixed on an inclined surface at 45 ° C., and distilled water at 20 ° C. was used to make a water drop of 0.1 ml.
Dropped. The water repellent degree was determined by observing the trace of the flow (JIS
According to P8137). The results are shown in Table 1. (Evaluation of slipperiness) The force required when a urethane rubber or SBR rubber with a load of 200 g was placed on the surface processed surface and pulled at 0.3 m / min in the direction parallel to the surface processed surface.
(g) was measured, and the force required for pulling / 200 was calculated as the dynamic friction coefficient. Moreover, this slipperiness was relatively evaluated from the touch. The results are shown in Table 1. The criteria for judgment are shown below. ◎ ・ ・ ・ ・ ・ Slip resistance is very high. ○ ... High slip resistance. △ ... Slightly slippery. ×: Sliding property.

Comparative Example 1 Same as Production Example 1 except that no synthetic rubber latex was blended and only 80 g of 8: 2 copolymer emulsion of n-butyl methacrylate and iso-butyl methacrylate (solid content 45%) was used. The surface-treated paper [5] prepared by the above method was evaluated for water repellency and slipperiness in the same manner as in Examples 1 to 4. The results are shown in Table 1.
Shown in. Comparative Example 2 Only 80 g of a copolymer latex of styrene-butadiene-acrylic acid (copolymerization ratio 58: 39: 3, Tg = 23 ° C.) was used without blending a resin emulsion having (meth) acrylate as a constituent unit. Other than that, the surface-treated paper [6] prepared by the same method as in Production Example 1 was evaluated for water repellency and slipperiness by the same method as in Examples 1 to 4. The results are shown in Table 1. Comparative Example 3 A surface-treated paper [7] prepared in the same manner as in Production Example 1 except that the surface-treated paper was dried at 40 ° C. for 1 minute was used in Examples 1 to.
Water repellency and slipperiness were evaluated by the same method as in 4. The results are shown in Table 1. Comparative Example 4 40 g of a 10% aqueous solution of oxidized starch was mixed with 40 g of a paraffin wax emulsion (solid content: 45%) to prepare a surface-treating agent. Next, using this surface-treating agent, a surface-treated paper [8] was produced in the same manner as in Example 1, and the water repellency and slipperiness were evaluated in the same manner as in Examples 1 to 4. The results are shown in Table 1.

[0014]

[Table 1] * The evaluation criteria for water repellency are as follows. R0: After continuous and showing a uniform width R2: After continuous and showing a width slightly narrower than a water drop R4: After continuous but some breaks ,
Clearly a narrower width than a water drop R6 ... Half of the trace is wet R7 ... 1/4 of the trace is wet by a long stretch of water R8 ... 1/4 or more of the trace Is spherical particles scattered R9 ... Spherical small water droplets scattered here and there R10 ..

[0015]

The surface-treating agent of the present invention makes it possible to impart high water repellency and slip resistance to the surface-treated paper. High water repellency is imparted not only to the surface-treated paper but also to these processed papers by internally adding a water-repellent agent to the color-developing layer of the pressure-sensitive paper or the pressure-sensitive layer of the thermal paper. Further, it becomes possible to obtain good slip resistance even with a water repellent agent for corrugated cardboard without performing anti-slip agent treatment. Further, the surface-treating agent in the present invention has low foaming property and low odor, and is useful from the viewpoint of coating workability and environment.

Claims (3)

[Claims] 1. A combination of an aqueous emulsion (A) of a resin containing 25% by weight or more of an alkyl (C1-12) (meth) acrylate as a constitutional unit and a synthetic rubber latex (B), ) And (B) solid content conversion weight ratio (B) / (A)
A surface treatment agent for paper having a viscosity of 0.05 to 20. 2. The surface treating agent for paper according to claim 1, wherein (A) is an aqueous emulsion of a resin containing butyl methacrylate as a constituent unit in an amount of 40% by weight or more. 3. A water repellency imparting agent comprising the paper surface treating agent according to claim 1 or 2.