JPH0555639B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to latexes for use as internal additives in various types of fibers that have excellent water resistance, and more particularly, to latexes that have excellent water resistance and are used as internal additives in fibers. This invention relates to conjugated diene latexes. (Prior art) Conventionally, sheets made from various types of fibers have been used mainly for gaskets, etc., but even when paper is made from only fibers, the fibers are only physically entangled.
Since the chemical bonding force between fibers is extremely weak, gaskets etc. with satisfactory strength cannot be obtained. Therefore, in order to increase the bonding strength between fibers, fibers are generally produced by an internal addition method using a natural or synthetic polymeric latex as a binder. (Problems to be Solved by the Invention) Acrylonitrile-butadiene copolymer latex has been used as a binder for the purpose of improving the strength of papermaking and imparting oil resistance. However, this latex contains polymerization agents such as surfactants and various inorganic salts used during polymerization, and because these are present in papermaking, sufficient water resistance cannot be obtained, and improvements are desired. ing. (Means for Solving the Problems) As a result of intensive research in order to solve the above-mentioned drawbacks, the present inventors have developed a method for converting unsaturated compounds containing epoxy groups into conjugated diene monomers and ethylene nitrile monomers by emulsion polymerization. It was discovered that internal addition using a latex copolymerized with acrylonitrile-butadiene copolymer improves the water resistance of papermaking compared to internal addition using a conventional acrylonitrile-butadiene copolymer latex. The present invention has now been completed. That is, the present invention provides a latex for internal addition to paper making, which is obtained by emulsion copolymerizing an epoxy group-containing monomer, a conjugated diene monomer, and an ethylene nitrile monomer. The epoxy group-containing monomer used in the present invention is an essential monomer for improving the water resistance of papermaking. The monomer containing an epoxy group may be any monomer that is radically copolymerizable with other monomers constituting the copolymer of the present invention, such as vinyl glycidyl ether, allyl glucidyl ether, methallyl glycidyl One or more types of ether, glycidyl acrylate, glycidyl methacrylate, etc. are used. The amount used is at least 0.1% by weight in the monomer mixture (hereinafter the same)
If the amount is less than 0.1% by weight, the water resistance of papermaking will not be improved. If it exceeds 10% by weight, the water resistance will be saturated, so further use is not necessary. Preferably it is 1 to 5% by weight. The conjugated diene monomer used in the present invention is
For example, isoprene, 1,3-butadiene, 2-
Methyl-1,3-butadiene, 2-chloro-1,
3-butadiene, 1,3-pentadiene, etc., and one or more of these may be used. Usage is usually 35
~98.9% by weight. If it is less than 35% by weight, the flexibility of the paper will be poor, and if it exceeds 98.9% by weight, the polymerization reaction rate will be reduced, and the strength of the paper will be reduced. Preferably it is 50 to 84% by weight. As the ethylene-based nitrile monomer, one type of nitrile such as acrylonitrile, methacrylonitrile, and α-chloro-acrylonitrile is used. The amount used is usually 1 to 55% by weight; if it is less than 1% by weight, the strength and oil resistance of the paper will be insufficient;
If it exceeds this amount, the flexibility of the papermaking product will decrease and the polymerization reaction rate will also decrease, which is not preferable. Preferably
It is 15-50% by weight. Further, if necessary, an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid, or an alkyl ester thereof may be included in an amount of 20% by weight or less in the total monomer mixture. The use of unsaturated carboxylic acid monomers is particularly desirable in increasing the stability of the latex. The latex of the present invention can be obtained by copolymerizing the above-mentioned monomers by conventional emulsion polymerization.
It may be a continuous type or the like, and is not particularly limited.
Further, the emulsifier, polymerization initiator, molecular weight regulator, and other polymerization agents used may be those used in ordinary emulsion polymerization, and are not particularly limited. Examples of fibers used to produce paper include asbestos, cellulose fibers, aromatic polyamide fibers, carbon fibers, phenol fibers, ceramic fibers, and inorganic fibers other than asbestos.
Optionally, minerals can be added to the fibers to produce dense sheets. As an inorganic substance,
Examples include clay talc, silicic acid, aluminum silicate, calcium carbonate, and the like. When manufacturing papermaking using the latex of the present invention, the latex of the present invention is used as a binder in a solid content of usually 0.5 to 100% by weight, preferably 1 to 30% by weight, based on the fibers, and is used in a beater or After adding the fibers in a process such as bochering and stirring thoroughly, if necessary, add 0.5 to 10% by weight of an inorganic salt, preferably sulfuric acid, or a polymer flocculant to complete fixation of the binder to the fibers. It is made into paper-like material using a paper-making machine. Thus, according to the present invention, compared to conventional paper making using a latex of acrylonitrile-butadiene copolymer containing epoxy groups as a binder, the paper has the same strength properties and oil resistance but has excellent water resistance. Paper making can be obtained. Paper making using the latex of the present invention is mainly useful for gaskets that require oil resistance. EXAMPLES The present invention will be explained in more detail with reference to Examples below. Example 1 In an autoclave equipped with a stirrer, water, butadiene, acrylonitrile, glycidyl methacrylate, sodium lauryl sulfate,
After charging t-dodecyl mercaptan, the mixture was heated to 35°C, and ammonium persulfate was added to start the reaction. At a polymerization conversion rate of 98% or higher (measured gravimetrically), the autoclave was cooled to room temperature to stop the reaction. The autoclave was kept at 35°C during the reaction. The obtained copolymer latex is referred to as latex A. Similarly, a copolymer latex using allyl glycidyl ether instead of glycidyl methacrylate (latex B) and a latex containing no epoxy machine (latex C) were obtained.

【table】

[Table] Asbestos was selected as the fiber for papermaking, and asbestos paper was produced using these latexes as a binder as follows. Crystalline asbestos (6D-5) 100g in water 15dm ³
After adding it to a ^3dm3 disintegrating machine (manufactured by Tester Sangyo Co., Ltd.) and stirring for 2 minutes, the latex
g (solid content concentration 25%) was added. After adding 30
Stir for 2 seconds, add 1.5 cm ³ (concentration 5%) of sulfuric acid, allow the latex to completely settle on the asbestos, and then add
Stir for seconds. Obtained asbestos slurry 1dm ³
was made into a paper using a hand paper testing machine (manufactured by Tester Sangyo Co., Ltd.), pressed at 5 kg/cm ² for 10 minutes to remove water, and then dried in an oven at 130°C for 10 minutes. The obtained asbestos paper was made into a 5 x 2 cm test piece, and its weight was measured. In order to evaluate water resistance, each test piece was fixed to a wire and immersed in a large tester equipped with a sulfuric cooling tube filled with distilled water.
It was heated in a 100°C oil bath for 5 hours. Take out the test piece and wrap it with towel paper (manufactured by Jujo Kimbali Co., Ltd.)
After lightly absorbing water, the weight of the test piece was measured, and the weight change rate was calculated by dividing the weight increase due to immersion by the weight before immersion. Table 2 shows the weight change rate of asbestos paper made using latexes A, B, and C when immersed in distilled water. The values in Table 2 are the average values of four test pieces.

[Table] From Table 2, when latexes A and B in which epoxy group-containing monomers were copolymerized were used, compared to latex C in which epoxy group-containing monomers were not copolymerized, It can be seen that the weight change rate after immersion in distilled water was improved. Furthermore, properties other than water resistance, such as tear strength and oil resistance, were tested, but no differences were observed due to the presence of epoxy groups. Example 2 Latex D obtained by polymerization in the same polymerization operation as in Example 1 according to the polymerization recipe in Table 3,
Using E, F, and G, asbestos paper was made in the same manner as in Example 1. The weight change rate of each asbestos paper after immersion in distilled water was measured. The results are shown in Table 4.

【table】

[Table] As is clear from Table 4, the weight change rate decreases as the amount of glycidyl methacrylate increases, indicating that the effect of the epoxy group appears. Furthermore, the effect of the product copolymerized with 13 parts of glycidyl methacrylate has been saturated. Example 3 According to the polymerization recipe in Table 5, aggregation was carried out in the same polymerization operation as in Example 1, and the obtained latex H,
Asbestos paper was made using I, J, K, and L in the same manner as in Example 1. The weight change rate of each asbestos paper after immersion in distilled water was measured. The results are shown in Table 6.

【table】

[Table] From Table 6, from the comparison when using latex H and K, and from the comparison when using latex J and L,
It can be seen that water resistance is significantly improved by copolymerizing glycidyl methacrylate even when the ratio of butadiene and acrylonitrile used is significantly changed. Example 4 18 g of Bulb (NBKP) and 1.15 dm ³ of water were added to the same disintegrator as in Example 1 and stirred for 5 minutes.
Then, talc (SS manufactured by Nippon Talc Co., Ltd.) 82
After stirring for 1 minute, 60 g of latex A obtained in Example 1 (solid content concentration 25% by weight) was added. Stir for 30 seconds, add 5 cm ³ of sulfuric acid (concentration 10% by weight) to completely fix the latex, and then
Stir for 30 seconds. After adding water to 450 cm ³ of the obtained slurry to make it 5 dm ³ , it was made into a paper using the same hand paper testing machine as in Example 1, pressed at 10 Kg/cm ² for 10 minutes to drain the water, and then placed in an oven for 130 cm. ℃ for 10 minutes. The obtained sheet was used as a 5 x 2 cm test piece.
Water resistance was evaluated in the same manner as in Example 1. The paper made using Latex C was also evaluated for water resistance. The evaluation is shown in Table 7.

[Table] It is clear from Table 7 that the latex copolymerized with glycidyl methacrylate has excellent water resistance even in pulp-tackle paper making.

Claims (1)

[Claims] 1. A latex for internal addition to paper making made by emulsion copolymerization of an epoxy group-containing monomer, a conjugated diene monomer, and an ethylene nitrile monomer.