GB2070024A - Paper-making size - Google Patents

Abstract

A paper-making size comprises an aqueous liquid containing a cationic compound prepared by reacting (A) an organic high- molecular-weight compound composed of (a) a main-chain high- molecular-weight portion (a) having a molecular weight of 200 to 10,000 and (b) an epoxy group, said organic high-molecular weight compound containing the epoxy group in an amount of 0.05 to 2 moles per 100 g thereof, with (B) a primary or secondary amine to produce a resin having a basic group and a hydroxyl group, and then treating the resin to render it water-soluble or water- dispersible by neutralisation with an organic or inorganic acid or by quaternisation with an organic halogen compound. Suitable components (A) are epoxidation products of polybutadiene, polyisobutylene and petroleum resins. The size may also comprise an emulsion polymer prepared in the presence of the cationic compound as emulsifying agent.

Description

SPECIFICATION Paper-making size This invention relates to a paper-making size, and more specifically, to a cationic self-fixable size which has a good sizing effect and does not require a fixing agent.

Many methods involving use of aluminium sulfate as a fixing agent for paper-making sizes have been practised in the past. These methods have to be operated within a low pH range (e.g., 2 to 6) of the paper stock slurry, and therefore have the defect that the quality of the paper is reduced, the paper machine undergoes corrosion, or calcium carbonate cannot be used as a filler. In an attempt to remedy this defect, much work has been done heretofore on the use of a cationic water-soluble polymer as a fixing agent instead of the aluminium sulfate, and the use of self-fixable sizes which do not require a fixing agent.The use of a petroleum resin size with polyethylenimine as a fixing agent (Japanese patent Publication No. 24923/75), and the use of an o-olefin acrylic acid copolymer with an aliphatic polyamine-epichlorohydrin reaction product as a fixing agent (Japanese Laid-Open Patent Publication No. 107202/75) are examples of the former. These sizes, however, have not gained commerical acceptance because they have a poor sizing effect, and the operation becomes complex owing to the use of a fixing agent.Examples of the latter includes a maleinized petroleum resin rendered cationic by reacting it with a polyalkylene polyamine (Japanese Patent Publications Nos. 2922/67 and 28722/71), and a quaternized product of a styrene/aminoalkyl acrylate copolymer or an a-olefin maleic anhydride copolymer rendered cationic by reacting it with an amine (Japanese Patent Publication No. 1 2292/67).

Among these cationic sizes, those which have a relatively good sizing effect are expensive, and when the solids concentration of an aqueous solution of the size is increased, the solution viscosity of the solution becomes high and it lends itself to inconvenient handling. Furthermore, paper obtained by using these sizes will have an excessively high wet strength, and disintegration of the used paper may require a long period of time. On the other hand, those which are relatively inexpensive have a poor sizing effect. Accordingly, these cationic sizes are used only for papers having special utility.

The present inventors have made extensive investigations in order to develop a size which does not require the use of a fixing agent, exhibits a high level of sizing effect, can be used over a broad pH range of the paper stock slurry, can give a high-concentration solution having a moderate viscosity, can be easily handled, and does not give paper of excessively high wet strength, thus permitting easy disintegration of the used paper.

Thus, according to this invention, there is provided a paper-making size comprising an aqueous liquid of a cationic compound prepared by reacting (A) an organic high-molecular-weight compound composed of (a) a main-chain high-molecular-weight portion (a) having a molecular weight of 200 to 10,000 and (b) an epoxy group of the following formula (1)

wherein R1 and R2 represent a hydrogen atom or a methyl gorup, X represents a hydrogen atom or a bond, and when X represents a bond, the carbon atom to which R1 is attached and the carbon atom to which R2 is attached may form part of the main chain, said organic high-molecular-weight compound containing the epoxy group in an amount of 0.05 to 2 moles per 1 00g thereof, with (B) a primary or secondary amine of the following formula (2)

wherein R3 and R4 represent the same or different organic groups having 1 to 10 carbon atoms, or one or R3 and R4 represents a hydrogen atom and the other represents an organic group having 1 to 10 carbon atoms, to produce a resin having a basic group and a hydroxyl group, and then treating the resin with at least one compound selected from the group consisting of organic acids, inorganic acids and organic halogen compounds to render it water-soluble or water-dispersible.

The size of the invention has an excellent sizing performance in a broad pH range of the paper stock slurry, can be formed into a high-concentration solution having a moderate solution viscosity, and does not excessively increase the wet strength of the resulting paper.

The main-chain portion of the resin used in this invention is derived from a high-molecular-weight compound having a number average molecular weight of 200 to 1 0,000. Preferably, it has an iodine value of 20 to 500, particularly 50 to 450, and contains a carbon-carbon double bond.Examples of such a high-molecular-weight compound include natural oils and fats such as linseed oil, tung oil, soybean oil and dehydrated castor oil, or so-called stand oils obtained by heat-treating these natural oils and fats to increase their molecular weight; and low polymers of conjugated diolefins such as butadiene, isoprene and piperylene, copolymers of a low degree of polymerization of at least two of these conjugated diolefins, and copolymers with a low degree of polymerization of at least one of these conjugated diolefins and an ethylenically unsaturated vinyl monomer such as an aliphatic or aromatic vinyl monomer, especially isoprene, diisobutylene, styrene, a-methylstyrene, vinyltoluene and divinylbenzene. Mixtures of two or more of these may also be used. These low polymers are produced by conventional methods.A typical manufacturing process comprises the anion polymerization of conjugated diolefins having 4 or 5 carbon atoms either singly, or with each other, or with not more than 50 mole %, based on the conjugated diolefin, of an aromatic vinyl monomer such as styrene, - methylstyrene, vinyltoluene or divinylbenzene at a temperature of OOC to 1 000C in the presence of an alkali metal or an organic alkali metal compound. In order to control molecular weight and obtain a palecolored low polymer of a low gel content, it is preferred to use a chain-transfer polymerization method which involves using an organic alkali metal compound such as benzyl sodium as a catalyst and a compound having an alkylaryl group such as toluene as a chain-transfer agent (U.S. Patent No.

tetrahydrofuran solvent using a polynuclear aromatic compound such as naphthalene as an activator and an alkali metal such as sodium as a catalyst (Japanese Patent Publications Nos. 17485/67 and an alkali metal such as sodium as a catalyst (Japanese Patent Publications Nos. 17485/67 and 27432/68), or a method which comprises performing the polymerization in an aromatic hydrocarbon such as toluene or xylene as a solvent and a dispersion of a metal such as sodium as a catalyst and controlling the molecular weight of the polymer by adding an ether such as a dioxane (Japanese Patent Publications Nos. 7446/57, 1245/58 and 10188/59).There can also be used a low polymer produced by a coordinated anion polymerization method which uses an acetylacetonate compound of a metal of Group VIII such as cobalt or nickel and an alkylaluminum halide as a catalyst (Japanese Patent Publications Nos. 507/70 and 30300/71).

Furthermore, a so-called petroleum resin having an unsaturated group produced by the cationic polymerization of a petroleum cracking fraction having 4 to 10 carbon atoms at O to 1000C with a Friedel-Crafts catalyst such as aluminum chloride, boron trifluoride or a complex of any of these, and a butadiene-isobutylene copolymer of a low degree of polymerization, polybutene, polypropylene, polystyrene, etc. which are produced by using the same kind of catalyst can also be used as the mainchain portion of the resin used in this invention.

If the aforesaid hydrocarbon resin has a molecular weight of more than 10,000, it is difficult to convert it into a size by the method of this invention. If, on the other hand, its molecular weight is lower than 200, it has too low a sizing effect to be practical.

When the hydrocarbon resin has an iodine value of less than 20, it is difficult to form into a size by the method of this invention. If its iodine value is larger than 500, the storage stability of the product tends to be reduced.

The epoxy group of general formula (1) may be introduced into the natural oil or fat or the conjugated diolefin lower polymer or copolymer by using a conventional method which comprises reacting such an oil or polymer with peracetic acid at a temperature of O to 1000C (Japanese Patent Publications Nos. 3239/58, 3240/58, and 15107/63).

Or the introduction of the epoxy group can be effected by graft-copolymerization of the aforesaid polymer or oil with an unsaturated compound having an epoxy group, for example an unsaturated glycidyl ether such as allyl glycidyl ether or methallyl glycidyl ether, or an unsaturated acid glycidyl ester such as glycidyl acrylate or glycidyl methacrylate.

The epoxy group content of the epoxy-containing high-molecular-weight compound used in this invention is preferably 0.05 to 2 mole equivalents, especially preferably 0.1 to 1 mole equivalent, per 100 g of the high-molecular-weight compound.

When the epoxy group content is less than 0.05 mole per 1 0O g of the high-molecular-weight compound, the high-molecular-weight compound has reduced water-solubility and is difficult to form into a size and its action as an emulsifier is reduced. If it is larger than 2 more equivalents, the sizing effect of the product is decreased.

The epoxy group-containing high-molecular-weight material used in this invention may include other functional groups such as a hydroxyl, ether, ester or acyl group. The contents of the other functional groups are not particularly limitative.

The epoxy group-containing high-molecular-weight compound is reacted with the amine of formula (2) usually at room temperature to 2200C, preferably 100 to 1 5000, in the presence or absence af a solvent in the presence or absence of a catalyst.

Examples of the amine of general formula (2) include dimethylamine, methylethylamine, diethylamine, methylpropylamine, ethylpropylamine, dipropylamine, dibutylamine, methylbutylamine, ethylbutylamine, diethanolamine, dipropanolamine, methylethanolamine, ethylethanolamine, dimethylaminoethylamine, dimethyl-a minopropylmethylamine, pyrrolidine, piperazine, morpholine and piperidine.

A solvent is not essential. But when the epoxy group-containing high-molecular-weight compound is solid or highly viscous at the reaction temperture, it is preferred to use a solvent. When the reaction is to be carried out in a solvent, the solvent should be inert to both the epoxy group-containing highmolecular-weight compound and the amine, and preferably dissolve both the resin and the amine.

Examples of solvents that can be used include benzene, toluene, xylene, cyclohexane, methyl Cellosolve, ethyl Cellosolve, propyl Cellosolve, butyl Cellosolve, ethyl ether, glyme and diglyme.

Usually, the reaction between the epoxy group-containing high-molecular-weight compound and the amine is carried out in the absence of catalyst. It may however be carried out using a catalyst.

Examples of catalysts that can be used in this reaction are phenol, organic acids such as acetic acid, a BF3-amine complex, amine salts such as p-toluenesulfonic acid amine salt, and aminoalcohols such as dimethylaminoethanol or dimethylaminopropanol.

The above reaction yields a compound having a basic group and a hydroxyl group which is represented by the following general formula.

The amount of the amine used in the reaction of it with the epoxy group-containing highmolecular-weight compound is adjusted according to the content of the basic group required in the final product. Usually, it is used in an amount of 0.05 to 5 equivalents, preferably 0.2 to 2 equivalents, per equivalent of the epoxy group in the high-molecular-weight compound.

Therefore, the unreacted epoxy groups or amine may remain to some extent. Any of these remaining epoxy groups or amine is not deleterious on the performance of the size of this invention.

Desirably, however, the unreacted amine is distilled off after the reaction in order to remove its inherent smell.

The resulting reaction product contains almost equimoiar proportions of amino groups and hydroxyl groups derived from the reaction of the epoxy groups of the high-molecular-weight compound with the amine. The presence of hydroxyl groups not derived from the reaction, for example those originally contained in a natural oil used as the high-molecular-weight compound, does not exert any adverse effect on the sizing property of the resin in accordance with this invention. Modified resins obtained by esterifying the above hydroxyl groups with organic acids, or by etherifying the hydroxyl groups with alcohols may also be used effectively in the invention.

The basic group-containing resin in accordance with the invention is converted to an acid salt by using an organic or inorganic acid and thus becomes a cationic water-soluble or water-dispersible compound. For this purpose, an inorganic acid such as hydrochloric acid, sulfuric acid, boric acid or phosphoric acid and an organic acid such as formic acid, acetic acid, oxalic acid, lactic acid or citric acid or a mixture of these may be used The amount of the acid is at least 0.5 mole per mole of the basic group in the basic group-containing resin.

Alternatively, the resin of this invention may be converted to a cationic water-soluble or waterdispersible compound by quaternizing the basic group with an organic halogen compound The organic halogen compound as used herein is represented by the following formula.

R5-Y (4) wherein R5 represents an organic radical having 1 to 20 carbon atoms, and Y represents a halogen atom.

Epihalohydrins such as epichlorohydrin or epiiodohydrin, alkyi halides such as methyl chloride or ethyl chloride, or the mixtures thereof are preferred. The amount of the quaternizing agent is usually at least 0.5 mole per mole of the basic group in the basic group-containing hydrocarbon resin. When the organic or inorganic acid is used in combination with the organic halogen compound as the quaternizing agent, the total amount of the acid and organic halogen compound is at least 0.5 mole per mole of the basic group in the resin. In this case, the ratio between the acid and the quaternizing agent is not restricted.

From the viewpoint of the cost of production, it is advantageous to use the acid in a greater amount. But when the sizing property and the water solubility or dispersibility of the resulting product are considered, the amount of the quaternizing agent is most preferably in the range of 0.5 mole to 1.0 mole per mole of the amino groups in the amino group-containing hydrocarbon resin.

The solid or liquid basic group-containing resin may be rendered water-soluble or water-dispersible with the quaternizing agentby mixing the resin with the quaternizing agent in the presence or absence of water at room temperature or an elevated temperature, and then adding water with stirring. Or this may be easily achieved by dissolving or dispersing the basic group-containing hydrocarbon resin in water using an acid, and then mixing the solution or dispersion with the quaternizing agent with stirring at room temperature or at an elevated temperature.

The resulting water-soluble or water-dispersible resin obtained had a solids concentration of usually about 1 to 60% by weight, preferably 3 to 50% by weight, and can be used directly as a papermaking size as desired.

The paper-making size of this invention may contain dispersed therein a polymer obtained by radical emulsion-polymerization of a polymerizable hydrophobic monomer, in addition to the cationic water-soluble or water-dispersible compound from the basic group-containing resin. Inclusion of this polymer further increases the sizing effect and solution viscosity of the size. Moreover, it gives paper having lower wet strength, and the disintegration of the used paper becomes easier.

Since the cationic compound mentioned above has excellent performance as an emulsifying agent in addition to its performance as a size, when radical emulsion-polymerization of the polymerizable hydrophobic monomer is carried out in an aqueous medium containing the above cationic compound, a size containing the emulsion polymer and the cationic compound can be conveniently produced.

In the emulsion-polymerization of the polymerizable hydrophobic monomer in the aqueous medium containing the cationic compound, the inclusion as an auxiliary dispersant of a small amount of a compound of the following general formula R6-O4CH2-CH2-OSO3M (6) wherein R6 represents a higher aliphatic or alicyclic hydrocarbon radical, n represents an integer of 2 or more, and M represents a monovalent metal element or -NH4, promotes emulsification in the aqueous medium.

The auxiliary emulsifier of formula (5) is known per se.

As stated hereinabove, the size of this invention also embraces an emulsion-type size which is obtained by dispersing a polymerizable hydrophobic monomer in an aqueous medium containing the cationic compound as an emulsifier with or without the compound of general formula (5) as an auxiliary dispersant, and subjecting the dispersion to radical emulsion-polymerization.

Radical emulsion-polymerization in an aqueous medium can be fully achieved by conventional polymerization techniques.

The ratio between the emulsifying agent and the polymerizable hydrophobic monomer in the radical emulsion-polymerization is not particularly restricted. From the standpoint of the stability of the emulsion as a paper-making size and of economy, the weight ratio of the former to the latter is about 1:1 to 1:4.

When the auxiliary dispersant of general formula (5) is used, its amount is up to 50% by weight based on the weight of the emulsifier in view of the stability of the emulsion and the performance of the size.

Examples of the polymerizable hydrophobic monomer used in the radical emulsion-polymerization include so-called hard hydrophobic monomers such as styrene, styrene derivatives (e.g., a- methylstyrene or vinyltoluene), acrylonitrile and acrylonitrile derivatives (e.g., methacrylonitrile), and socalled soft hydrophobic monomers such as acrylic acid esters and methacrylic acid esters (e.g., n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethyl hexyl acrylate, cyclohexyl methacrylate, butyl methacrylate or 2-ethylhexyl methacrylate). These monomers are used singly or as a least one hard hydrophobic monomer and at least one soft hydrophobic monomer is used. The use of a mixture of styrene and 2-ethylhexyl acrylate brings about favorable results both in performance and cost.

In addition to the polymerizable hydrophobic monomer, another monomer may be used in an amount of up to 30%, preferably up to 10%, based on the entire monomers in the emulsion polymer. For example, acrylamide, an acrylamide derivative such as methacrylamide or an cz" -monolefinically unsaturated acid such as acrylic acid, methacrylic acid or maleic acid is used.

In the radical emulsion-polymerization, ordinary radical-forming initiators which are generally water-soluble can be used. Persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, and perborates such as sodium perborates, and hydrogen peroxide are preferred.

The amount of the radical-forming initiator is generally 0.1 to 4% by weight based on the weight of the monomer.

The polymerization can be performed at a pH of 2 to 12. The resulting polymer dispersion usually has a solids concentration of about 1 to about 50% by weight, preferably 3 to 50% by weight, and can be used directly as a paper-making size, as desired.

Advantageously, the size of this invention can be obtained in a low viscosity; for example, a size having a solids concentration of 1 5% by weight and a viscosity of 0.5 to 2 centistokes at 400C can be obtained.

Since the aforesaid basic group-containing resin can be easily rendered water-soluble or waterdispersible at the place of use of the size of this invention, the inconvenience of transporting a large quantity of aqueous material can be avoided. The size of this invention has an effect of moderately increasing the wet strength of paper, although the effect varies depending upon the type of the pulp or the amount of the size used. When the amount of the size used is within the range of 0.05 to 3.0% by weight based on the pulp, the wet strength of paper does not become excessively high, and the used paper can be easily disintegrated.

The size of this invention may be used in combination with a filler such as calcium carbonate, clay, talc, titanium white, white clay, zinc oxide, diatomaceous earth or lithopone, a paper strength increasing agent, a filtrability improver, and other paper-making chemicals.

In use, the size of this invention can be handled in the same way as conventional self-fixable cationic sizes. It can be used both in an internal sizing procedure involving adding it simply to a pulp slurry, and a surface sizing procedure involving dipping paper in a size solution and then drying the paper. When the size of this invention is to be added to the pulp slurry it is used in an amount of 0.01 to 5% by weight based on the dry weight of the pulp slurry, and when the pH of the pulp slurry is in the range of 3 to 11, it can be used without undergoing substantial influence by the pH.

The following Examples further illustrate the present invention specifically.

EXAMPLE 1 A 30-liter autoclave was charged under nitrogen stream with 1 mole of benzyl sodium, 4.5 moles of toluene and 1 5 liters of benzene, and after the temperature was raised to 300 C, 1 0 liters of butadiene was charged into the autoclave over the course of 4 hours while maintaining the temperature at 300 C.

Then, the catalyst was decomposed with water, and the reaction mixture was washed with water to remove the catalyst residue. Thereafter, the toluene, benzene and the unreacted butadiene were distilled off to prepare a polybutadiene (A) having an iodine value of 430 and a number average molecular weight of 2,000.

In a 2-liter flask, 500 g of the polybutadiene (A) and 5 g of formic acid were dissolved in 300 g of toluene. While the reaction temperature was maintained at 80"C with stirring, 250 g of a 60% aqueous solution of hydrogen peroxide was added dropwise. After the addition, the mixture was reacted at 800C for 4 hours. After the reaction, the aqueous layer was removed, and the residue was heated to 1 000C under reduced pressure to remove water, toluene, formic acid and the unreacted hydrogen peroxide to afford 530 g of a colorless clear epoxy group-containing polybutadiene (B) which had an epoxy group content of 0.3 mole per 100 g thereof.

One hundred grams of the epoxy group-containing polybutadiene (B) was dissolved in 50 g of butyl Cellosolve, and the solution was charged into a 300 ml autoclave. Dimethylamine (25 g) was introduced under pressure into the autoclave, and the mixture was reacted at 1500C for 3 hours with stirring. After the reaction, the unreacted dimethylamine and butyl Cellosolve were removed by heating the reaction mixture to 1 300C under reduced pressure, thereby forming 110 g of a brown amino group containing polybutadiene (C) which had an amino group content of 0.18 mole per 1 per 100 g thereof.

Then, 40 g of the amino group-containing polybutadiene (C) was taken into 200 ml flask, and while it was stirred at 500 C, a 20% aqueous solution of hydrochloric acid and water were added until the mixture had a pH of 7. Thus, a brown clear aqueous solution (d) having a solids concentration of 35% was obtained. The aqueous solution (D) had a viscosity, measured at 400 C, in a concentration of 15%, of 2.201 centistokes.

EXAMPLE 2 One hundred grams of the aqueous solution (D) obtained in Example 1 was taken into a 200 ml flask, and with stirring, 5 g of epichlorohydrin was added at 350C. Then, the mixture was reacted at 350C for 4 hours to afford a brown clear aqueous solution (E). The resulting aqueous solution (E) had a viscosity, measured at 400C in a concentration of 15% by weight, of 2.212 centistokes.

EXAMPLE 3 A fraction having a boiling range of 20 to 800C obtained as a by-product in the steam cracking of naphtha was heated at 1 000C for 4 hours to dimerize most of the cyclopentadiene in it to dicyclopentadiene. The product was then distilled, and 800 g of the resulting fraction having a boiling range of 200C to 800C was taken into a 2-liter flask. With stirring, 8 g of a-boron trifluoride/phenol complex was added while maintaining the reaction temperature at 350C. The reaction was performed at 350C for 3 hours. Then, the catalyst was decomposed with an alkali, and the reaction mixture was washed with water to remove the catalyst residue. The unreacted fraction was then distilled off to afford 340 g of a hydrocarbon resin (F) having an iodine value of 1 50 and a number average molecular weight of 600.

Then, 200 g of the resin (f) was dissolved in 600 g of benzene, and with stirring, 300 g of an ethyl acetate solution containing 30% by weight of peracetic acid was added dropwise while maintaining the reaction temperature at 350C. After the addition, the reaction temperature was maintained at 550C, and the reaction was carried out for 5 hours. After the reaction, the oily layer was washed with water to remove the unreacted peracetic acid and acetic acid, and heated under reduced pressure to 900C to remove the solvent. Thus, 222 g of a pale yellow epoxy group-containing hydrocarbon resin (G) was obtained. The resin (G) had an epoxy group content of 0.5 mole per 100 g thereof.

Then, 100 g of the resin (G) was dissolved in 100 g of butyl Cellosolve, and the solution was charged into a 300 ml. Autoclave. Dimethylamine (30 g) was introduced under pressure into the autoclave, and with stirring, the mixture was reacted at 60"C for 1 0 hours. After the reaction, the unreacted dimethylamine and butyl Cellosolve were removed by heating to 11 00C under reduced pressure to afford 11 3 g of a brown amino group-containing hydrocarbon resin (H). This resin had an amino group content of 0.25 mole per 100 g thereof.

Then, 30 g of the amino group containing resin (H) was taken into a 200 ml flask, and with stirring at 500 C, a 30% aqueous solution of lactic acid and water were added until the mixture had a pH of 7.2.

Thus, a brown clear aqueous solution (I) having a solids concentration of 40% was obtained. The solution (I) had a viscosity, measured at 400C in a concentration of 15% by weight, of 1.325 centistokes.

EXAMPLE 4 Thirty grams of the amino group-containing hydrocarbon resin (H) produced in Example 3 was taken into a 200 mi flask, and 5g of 20% hydrochloric acid and 40 g of water were added. The mixture was stirred at 500C to form a suspension. Then, 6 g of epichlorohydrin was added while maintaining the suspension at 300C with stirring. The mixture was then reacted at 300C for 4 hours to afford a brown clear aqueous solution (J). The aqueous solution (J) had a viscosity, measured at 400C in a concentration of 15% by weight, of 1.331 centistokes.

EXAMPLE 5 A 1-liter flask was charged with 0.5 mole of polyisobutylene having an average molecular weight of 380 and an iodine value of 72 and 200 ml of n-hexane, and while maintaining the temperature at 20 to 300C with stirring, a mixture of 0.6 mole of peracetic acid (as 40% by weight acetic acid solution) and 0.3 mole of sodium acetate was added dropwise. The reaction was subsequently performed for 4 hours.

The reaction mixture was distilled under reduced pressure to remove the n-hexane, and the residue was poured into 100 ml of water. The mixture was extracted several times with ether, washed with water and sodium carbonate, and dried. The ether solvent was evaporated off to afford 195 g of a pale yellow epoxy group-containing polyisobutylene (K) having an epoxy group content of 0.21 mole per 100 g thereof.

Then, 100 g of the polyisobutylene (K) and 30 g of diethylamine were dissolved in 500 ml of toluene.

After purging with nitrogen gas, the solution was reacted in a 1-liter autoclave with stirring at 11 00C for 8 hours. The toluene was then removed by vacuum distillation to afford 113 g of a brown amino groupcontaining polyisobutylene (L) having an amino group content of 0.17 mole per 100 g thereof.

Then, 1 5 g of the amino group-containing poly-isobutylene (L) was taken into a 200 ml flask, and with stirring at 700C, a 20% aqueous solution of hydrochloric acid and water were added until the mixture had a pH of 7. The insoluble matter was removed by filtration to obtain a stable aqueous dispersion (M) having a solids concentration of 40%. The dispersion (M) had a viscosity, measured at 400C in a concentration of 15% by weight, of 1.124 centistokes.

EXAMPLE 6 An Erlenmeyer flask was charged with 50 g of the aqueous dispersion (M) obtained in Example 5, and 3 g of epichlorohydrin was added. The reaction was then performed at 300C for 5 hours to afford a stable aqueous dispersion (N). The aqueous dispersion (N) had a viscosity, measured at 400C in a concentration of 15% by weight, of 1.148 centistokes.

EXAMPLE 7 A 300 ml flask was charged with 50g of an aqueous solution obtained in the same manner as in the production of the aqueous solution (LE) in Example 2. Then, 25 g of styrene, 13 g of 2-ethylhexyl acrylate and 80 g of water were added. Then, with stirring at 650C, a mixture of 3.0 g of a 30% aqueous solution of hydrogen peroxide and 209 of water was added dropwise. After the addition the reaction was performed for 5 hours to afford a stable dispersion (0). The aqueous dispersion (0) had a viscosity, measured at 400C in a concentration of i 5 iO by weight of i .892 centistokes.

EXAMPLE 8 A 200 ml flask was charged with 30 g of an aqueous solution obtained in the same manneras in the production of the aqueous solution (E) in Example 2, and 22 g of styrene, 11 g of 2-ethylhexyl acrylate, 70 g of water, and 0.2 g of Emal 20C [having the formula R-O--CCH,-CH,-O--3-,SO,Na, a registered trademark of Kao-Atlas Co., Ltd.] were added. While maintaining the temperature at 650C with stirring, a mixture of 2.0 g of a 30% aqueous solution of hydrogen peroxide and 15 g of water was added dropwise. After the addition, the reaction was performed for 5 hours to give a stable dispersion (P) having a viscosity, measured at 400C in a concentration of 15% by weight, of 1.788 centistokes.

EXAMPLE 9 A 300 ml flask was charged with 50 g of an aqueous solution obtained in the same manner as in the production of the aqueous solution (E) in Example 2, and 25 g of styrene, 1 5 g of lauryl methacrylate, 80 g of water and 0.3 g of Emal 20C were added. While maintaining the temperature at 750C with stirring, a mixture of 0.3 g of potassium peroxydisulfate and 20 g of water was added dropwise. After the addition, the reaction was carried out for 3 hours to give a stable dispersion (Q) having a viscosity, measured at 400C in a concentration of 15% by weight, of 1.760 centistokes.

EXAMPLE 10 A 300 ml flask was charged with 50 g of an aqueous solution obtained in the same manner as in the production of the aqueous solution (J) in Example 4, and 25 g of styrene, 13 g of 2-ethylhexyl acrylate, 0.3 g of Emal 20C and 80 g of water were added. While maintaining the temperature at 700C with stirring, a mixture of 3.0 g of a 30% aqueous solution of hydrogen peroxide and 20 g of water was added dropwise. After the addition, the reaction was carried out for 5 hours to give a stable dispersion (R) having a viscosity, measured at 400C in a concentration of 15% by weight, of 1.590 centistokes.

COMPARATIVE EXAMPLE 1 A synthetic neutral size and a petroleum resin neutral size which are commercially available had a viscosity, measured at 400C in a concentration of 15% by weight, of 6.321 centistokes, and 2.562 centistokes, respectively.

It is clear therefore that the sizes as aqueous solution or dispersion obtained in Examples 1 to 10 above have a lower viscosity than the commercially available synthetic neutral size and petroleum resin neutral size.

COMPARATIVE EXAMPLE 2 A flask was charged with 0.5 mole of triisobutylene having an average molecular weight of 168 and 200 ml of n-hexane, and by the same procedure as in Example 5, 94 g of an epoxy groupcontaining triisobutylene (S) was obtained. This product had an epoxy group content of 0.6 mole per 1 00 g thereof. Then, 50 g of the epoxy group-containing triisobutylene (S) was dissolved in 50 g of butyl Cellosolve, and the solution was charged into an autoclave. Dimethylamine (15 g) was introduced under pressure into the autoclave, and the mixture was reacted at 11 00C for 8 hours with stirring.The unreacted dimethylamine and butyl Cellosolve were removed by heating to 11 00C under reduced pressure to give 62 g of a brown amino group-containing triisobutylene (T) having an amino group content of 0.45 mole per 100 g thereof. Then, 20 g of the amino group-containing triisobutylene (T) was taken into a flask, and with stirring at 700 C, a 20% aqueous solution of hydrochloric acid and water were added until the mixture had a pH of 7. The insolubie matter was removed by filtration to give an aqueous solution (U) having a solids concentration of 20%.

COMPARATIVE EXAMPLE 3 Fifty grams of the aqueous dispersion (U) obtained in Comparative Example 2 was taken into an Erlenmeyerflask, and 2.5 g of epichlorohydrin was added. Then, the reaction was carried out at 3O0C for 5 hours to give an aqueous solution (V).

COMPARATIVE EXAMPLE 4 A 300 ml flask was charged wtih 10 g of an aqueous solution obtained in the same manner as in the preparation of the aqueous solution (E) in Example 2, and 25 g of styrene, 1 3 g of 2-ethyl-hexyl acrylate and 80 g of water were added. While maintaining the temperature at 650C with stirring, a mixture of 20 g of water and 3.0 g of a 30% aqueous solution of hydrogen peroxide was added. After the addition, the reaction was carried out for 5 hours to given an emulsion (W). This emulsion (W), on standing at room temperature for 24 hours, formed a small amount of a precipitate, and thus had much lower stability than the dispersions obtained in Examples 7 to 1 0.

TEST EXAMPLE 1 The sizes of the invention obtained in Examples 1 to 10 and the commercially available synthetic neutral size and petroleum neutral size in Comparative Example 1, and the sizes in Comparative Examples 2 to 4 were tested for the degree of sizing, and the results are shown in Table 1.

The test conditions were as follows: Hand-mold paper preparing conditions Pulp: LBKP, degree of beating 400 SR Basis weight: 60 g/m2 Amount of the size added: % by weight as the solids based on the bone dry weight of pulp Amount of filler added: 20% by weight of calcium carbonate based on the bone dry weight of the pulp Water four paper making: a 1:9 mixture of sea water and deionized water pH of the paper-making water: 6.5-8.0 Paper machine: TAPPI standard machine Drying:Dried at 1 050C using a rotary dryer Method of measuring the degree of sizing JIS P-8122 stoechigt method TABLE 1

Table 1 shows that the sizes of this invention have better effects than the commercially available synthetic neutral size or petroleum resin neutral size, and that the sizes of Comparative Example 2 and 3 in which the molecular weight is outside the invention and the size of Comparative Example 4 in which the composition is outside the invention have lower sizing effects.

TEST EXAMPLE 2 The sizes of the invention obtained in Examples 1 to 10 and the commercially available synthetic neutral size of Comparative Example 1 were tested for wet strength and disintegrability, and the results are shown in Table 2.

The test conditions were as follows: Han d-mold paper preparing conditions Same as in Example 1.

Method for measuring wet bursting strength Hand-mold paper was dipped for 5 minutes in deionized water at 200C. The excess of water was absorbed by filter paper, and the bursting strength of the paper was measured by a Muellen low pressure tester.

Method for measuring the disintegration time One gram of hand-mold paper was put into a small-sized electrical mixer, and after adding 100 g of pure deionized water at 200C, the mixture was rotated. The time required until the paper was disintegrated completely was measured. Shorter disintegration times means better results.

TABLE 2

As shown in Table 2, the sizes of this invention have an effect of moderately increasing the wet strength of paper. The commercially available synthetic neutral size of Comparative Example 1 was found to have a disintegration time, measured in the same way as above, of 3.0 minutes (when the amount of the size was 1.0% by weight) and 4.5 minutes (when the amount of the size was 2.0% by weight), showing better disintegrability imparted by the size of this invention.

Claims (8)

1. A paper-making size comprising an aqueous liquid of a cationic compound prepared by reacting (A) an organic high-molecular-weight compound composed of (a) a main-chain high-molecular-weight portion having a molecular weight of 200 to 10,000 and (b) an epoxy group of the formula

wherein R1 and R2 represent a hydrogen atom or a methyl group, X represents a hydrogen atom or a bond, and when X represents a bond, the carbon atom to which R, is attached and the carbon atom to which R2 is attached may form part of the main chain, said organic high-molecular-weight compound containing the epoxy group in an amount of 0.05 to 2 moles per 100 g thereof, with (B) a primary or secondary amine of the formula

wherein R3 and R4 represent the same or different organic groups having 1 to 10 carbon atoms, or one of R3 and R4 is a hydrogen atom and the other represents an organic group having 1 to 10 carbon atoms, t Droduce a resin having a basic group and a hydroxyl group, and then treating the resin with at least one compound selected from organic acids, inorganic acids and organic halogen compounds to render it water-soluble or water-dispersible.

2. A size according to claim 1 wherein the aqueous liquid further contains dispersed therein a radical emulsion polymer of a polymerizable hydrophobic monomer.

3. A paper size according to claim 2 wherein the aqueous liquid containing the cationic compound and the radical emulsion-polymer is obtained by radical emulsion-polymerization of the polymerizable hydrophobic monomer in an aqueous medium containing the cationic compound.

4. A size according to claim 3 wherein the radical emulsion-polymerization of the polymerizable hydrophobic monomer is carried out in an aqueous medium containing the cationic compound and a compound of the general formula R5-OACH2-CH2-O4SQ M wherein, R5 represents a higher aliphatic or alicyclic hydrocarbon radical, n is an integer of 2 to 40, and M represents a monovalent metal element or -NH4.

5. A size according to claim 2, 3 or 4 wherein the polymerizable hydrophobic monomer is a dompound consisting mainly of styrene.

6. A size according to claim 2, 3 or 4 wherein the polymerizable hydrophobic monomer is a mixture consisting mainly of styrene and 2-ethyl-hexyl acrylate.

7. A size according to claim 1 substantially as described with reference to any one of the Examples.

8. Paper when sized using a size as claimed in any one of the preceding claims.