JP5152636B2 - Surface sizing agent for papermaking - Google Patents

Description

The present invention relates to a surface sizing agent for papermaking.

  The surface sizing agent for papermaking is a chemical that can give a sizing effect (controls the liquid absorbency of the paper and suppresses ink bleeding, etc.) by applying it to the paper. And size effects such as writing ability can be improved. Examples of such a surface sizing agent include a surface containing a copolymer mainly composed of a hydrophobic unsaturated monomer such as a (meth) acrylic acid ester monomer component and an anionic vinyl monomer such as (meth) acrylic acid. Surface sizing agent containing a sizing agent (see Patent Document 1) and a copolymer mainly composed of a hydrophobic unsaturated monomer such as a (meth) acrylic acid ester monomer component and a cationic vinyl monomer such as dimethylaminopropylacrylamide (See Patent Document 2).

The paper surface sizing agent may be used alone for coating on paper, but in many cases, other components such as starch and inorganic salts are mixed to prepare a coating solution and applied to paper. It is used for coating.
However, since this sizing agent itself is a copolymer having both a hydrophobic group such as a (meth) acrylic acid ester monomer component and a hydrophilic group such as acrylic acid or dimethylaminopropylacrylamide, it has a surface active action. There is a problem that the coating liquid is caused to foam, which adversely affects the coating operation on the paper. In particular, the water-soluble surface sizing agent for papermaking is more advantageous than the emulsion type in terms of size effect, but has a strong tendency to foam. Therefore, among various coating methods, such as gate roll coating, etc. There is a problem in that it is difficult to adopt a method that easily foams, and the coating method is restricted. For this reason, in order to reduce foaming, an antifoaming agent is usually added to the coating liquid. However, since the antifoaming agent often has an adverse effect on the size effect, it has an excellent size. There is a demand for a water-soluble surface sizing agent for papermaking that can reduce foaming during coating while having an effect.

JP2001-232932 JP 2007-119944 A

An object of the present invention is to provide a paper sizing surface sizing agent, particularly a water-soluble paper sizing surface size, in which foaming is reduced during a paper coating operation while maintaining high size performance.

  As a result of studies to solve the above problems, the present inventors have polymerized a specific vinyl monomer component and a crosslinkable monomer component in the presence of a chain transfer agent, the main component being a (meth) acrylate monomer component. It was found that the above-mentioned problems can be solved by using a sizing agent containing a copolymer obtained in this way, and the present invention has been completed.

That is, the present invention provides a monomer component containing a (meth) acrylic acid ester monomer component , a cationic vinyl monomer component and a crosslinkable monomer component having a plurality of radically polymerizable functional groups in the molecule, and 100 parts by weight of the total monomer components. Water-soluble surface sizing agent for papermaking containing a copolymer obtained by copolymerization in the presence of 0.01 to 20 parts by weight of a chain transfer agent; (meth) acrylate monomer in all monomer components content of 40 to 85 mol% of the component, mosquito thione vinyl monomer component is 14 to 59 mol%, the containing 0.0001 mole% crosslinking monomer component having a plurality of radically polymerizable functional groups in a molecule Paper sizing agent; chain transfer agent is represented by the general formula (1)

(Wherein R is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 8) . The surface sizing agent for papermaking as described above, wherein the crosslinkable monomer component having a radical polymerizable functional group is bis (meth) acrylamides and / or di (meth) acrylic esters ; the weight average molecular weight of the copolymer is 5000 papermaking surfaces sizing agent of the claimed is ～500000 relates to.

ADVANTAGE OF THE INVENTION According to this invention, foaming of the surface sizing agent for paper manufacture at the time of the coating operation to paper, or the coating liquid containing it can be reduced, maintaining a high size performance. In particular, the water-soluble surface sizing agent for papermaking of the present invention is reduced in foaming even in a gate roll coating method that has been conventionally difficult to apply due to easy foaming, and is subject to restrictions on the coating method. Without being subjected to a coating process.

The surface sizing agent for papermaking of the present invention polymerizes a (meth) acrylic acid ester monomer component , a cationic vinyl monomer component and a crosslinkable monomer component having a plurality of radical polymerizable functional groups in the molecule in the presence of a chain transfer agent. The copolymer obtained is obtained.

The cationic vinyl monomer constituting the copolymer of the present invention refers to a vinyl monomer component having a tertiary amino group or a quaternary amino group.
Examples of vinyl monomers having a tertiary amino group include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, and diethylaminopropyl (meth) acrylate. Dialkylaminoalkyl (meth) acrylate, and dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, etc. include dialkylaminoalkyl (meth) acrylamide etc. It is done.

Examples of the vinyl monomer having a quaternary amino group include those obtained by reacting the vinyl monomer component having a tertiary amino group with a quaternizing agent. It can also be obtained by reacting a copolymer obtained using the vinyl monomer component having the tertiary amino group with a quaternizing agent. By making a copolymer of vinyl monomers having a quaternary amino group, a good size effect can be exhibited in a wide pH range including the alkali side.
Examples of the quaternizing agent include conventionally known ones such as oxides, organic halides, dimethyl sulfate, and diethyl sulfate. Specific examples of the oxides include alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide, and styrene oxide. Examples of the organic halide include methyl chloride, ethyl chloride, benzyl chloride, epichlorohydrin, glycidyltrimethylammonium chloride, and 3-chloro-2-hydroxyammonium chloride.

The crosslinkable monomer having a plurality of radically polymerizable functional groups in the molecule constituting the copolymer of the present invention (hereinafter simply referred to as a crosslinkable monomer) may have a plurality of radically polymerizable functional groups in the molecule. As long as the polymer is used to introduce many branched structures into the copolymer, it can be used without particular limitation. Examples of those having a plurality of radically polymerizable functional groups in the molecule include 2 to 4 functional crosslinkable monomers. Specifically, examples of the bifunctional crosslinkable monomer include methylenebis (meth) acrylamide, Di (meth) acrylic esters such as ethylene bis (meth) acrylamide, bis (meth) acrylamides such as hexamethylene bis (meth) acrylamide, ethylene glycol di (meth) acrylic ester, diethylene glycol di (meth) acrylic ester, adipine Examples include divinyl esters such as divinyl acid and divinyl sebacate, diallyldimethylammonium, diallyl phthalate, diallyl chlorendate, divinylbenzene, and the like. Examples of the trifunctional monomer include 1,3,5 triacryloylhexahydro-S-triazine, triallyl isocyanurate, triallylamine, triallyl trimellitate, N, N-diallylacrylamide and the like.

Examples of the tetrafunctional monomer include tetramethylolmethane tetraacrylate, tetraallyl pyromellitate, N, N, N ′, N′-tetraallyl-1,4 diaminobutane, tetraallylamine salt, tetraallyloxyethane, and the like . These can be used in combination or two or more alone type. Among these, bis (meth) acrylamides and di (meth) acrylic esters are preferable because reaction control during production is easy. By using such a crosslinkable monomer, an appropriate branched structure is formed in the copolymer, so that the viscosity of the resulting sizing agent can be suppressed to a low level and foamability can be reduced.

As a use ratio of the monomer component of the copolymer which is the main component of the sizing agent for papermaking of the present invention, from the viewpoint of securing a sufficient size effect and reducing foaming, preferably the (meth) acrylic acid ester monomer component is used. the total monomer components in the 40 to 85 mol%, Ca thione vinyl monomer component 1 4-59 mol%, crosslinking monomer component is 0.0001 mol%, more preferably, (meth) acrylic acid ester monomer component of about 45 to 80 mol%, Ca thione monomer component is 19 to 54 mol% of crosslinking monomer component is about 0.001 mol%.

By making the said (meth) acrylic acid ester monomer component 40 mol% or more, it is preferable because a size effect improves, By making it 85 mol% or less, moderate water solubility can be provided, and the uniform surface sizing agent for papermaking This is preferable.
When the crosslinkable monomer component is 0.0001 mol% or more and 10 mol% or less, it is preferable in that a uniform and sufficient crosslinked structure can be stably formed between the respective polymers of the copolymer.

The copolymer of the present invention can be used in combination with any other monomer copolymerizable with the monomer components constituting the copolymer as long as the object of the present invention is not impaired. Examples of such an optional monomer include styrenes, (meth) acrylonitrile, vinyl acetate, (meth) acrylamide, α-olefins having 6 to 22 carbon atoms, and vinylpyrrolidone. Moreover, the usage-amount of this monomer is less than 20 mol% normally in a copolymer, Preferably it is less than 10 mol%.

It does not specifically limit as a chain transfer agent used for this invention, A well-known thing can be used.
Specifically, for example, t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, mercaptopropionic acid dodecyl ester, cumene, carbon tetrachloride, α-methylstyrene dimer, terpinolene, etc., mercaptoethanol, thioglycolic acid, And its salts, alcohols such as pentanol, polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, polyglycerin, polyethers such as a copolymer compound of ethylene oxide and propylene oxide, polyvinyl alcohol, polyvinylamine, polyacrylic acid Or acrylics such as salts thereof, styrene-maleic acid copolymers or esters thereof, polysaccharides such as carboxymethyl cellulose, polyesters, polyamide poly Polyamides such as Min compounds, the following general formula (1)
General formula (1)
(Wherein R is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, n is an integer of 1 to 8).
Specific examples include sulfonic acid group-containing unsaturated monomers having an allyl group such as allyl sulfonic acid, sodium allyl sulfonate, methallyl sulfonic acid, sodium methallyl sulfonate, and ammonium methallyl sulfonate. Among the chain transfer agents exemplified above, a sulfonic acid group-containing unsaturated monomer having an allyl group is preferred because it has the highest chain transfer effect.

  The amount of the chain transfer agent used is the total amount of monomers constituting the copolymer, that is, the (meth) acrylate monomer component, the anionic vinyl monomer component and / or the cationic vinyl monomer component, and the crosslinkable monomer. It is necessary to use in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of components (when other optional monomer components are used in combination), more preferably Is 0.1 to 5 parts by weight. When the amount of chain transfer agent used is less than 0.01 parts by weight, the molecular weight of the copolymer becomes too high and the aqueous solution gels. When the amount exceeds 20 parts by weight, the molecular weight becomes too low and the size effect is increased. Deteriorate.

Although the manufacturing method of the copolymer of this invention is not specifically limited, Various well-known polymerization methods, such as solution polymerization and suspension polymerization, are employable.

For example, in the case of producing by a solution polymerization method, a (meth) acrylic acid ester monomer component, an anionic vinyl monomer and / or a cationic vinyl monomer component, a crosslinkable monomer is added to a reaction vessel equipped with a suitable heating device and a stirrer. In addition, a predetermined amount of a chain transfer agent and other optional monomers used as necessary is charged, and then water and an organic solvent are charged into the container to dissolve these monomer components. Furthermore, a known polymerization initiator is added and mixed, and the temperature of the reaction system is raised to about 80 to 130 ° C. in a nitrogen stream. The polymerization reaction is carried out for about 4 hours by refluxing, and the organic solvent is distilled off. .

  As the organic solvent used for solution polymerization, aromatic hydrocarbons such as benzene and toluene, lower ketones such as acetone and methyl ethyl ketone, alcohols such as n-propyl alcohol and iso-propyl alcohol, and the like can be used. . The polymerization initiator is not particularly limited, but for example, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-methylvaleronitrile, benzoyl peroxide, cumene hydro Organic peroxides such as peroxide, t-butyl hydroperoxide, dicumyl peroxide, lauryl peroxide, persulfates such as ammonium persulfate and potassium persulfate, and reductions such as sodium bisulfite Any of the redox initiators combined with an agent can be employed. The amount of the polymerization initiator used may be appropriately determined in consideration of the polymerization rate, the molecular weight of the copolymer to be obtained, and the like. About 1 to 10% by weight is preferable.

  The weight average molecular weight of the copolymer of the present invention is preferably about 5,000 to 500,000 in terms of polystyrene by gel permeation chromatography from the viewpoint of ensuring a sufficient size effect and coating workability.

  The copolymer thus obtained has a solid content concentration of usually 15 to 30% by weight, a viscosity (B-type viscometer: 25 ° C.) at a solid content concentration of 25% by weight is usually 10 to 50000 mPa · s, and the pH is anionic. In the case of a polymer obtained by polymerizing monomers, usually 8.0 to 10.0, and in the case of a polymer obtained by polymerizing a cationic polymer or an anionic monomer and a cationic monomer in combination, pH 2.0 to It is adjusted to 6.0 and used as a surface sizing agent for papermaking.

  In addition, the paper size sizing agent of the present invention can be used alone for coating, but water-soluble polymers such as starch, carboxymethyl cellulose, acrylamide polymers, polyvinyl alcohol, antifoaming agents, anti-slip agents, preservatives. It can also be used as a coating liquid by mixing with a rust inhibitor, a thickener, a pH adjuster, an antioxidant, a film increasing aid, a pigment, and a dye.

The surface sizing agent for papermaking of the present invention is applied to the above various base papers using a conventionally known coating method such as impregnation method, size press method, calendar method, spray method, gate roll coater, etc. . The coating amount is usually about 0.001 to 5 g / m ² (solid content), preferably 0.005 to 1 g / m ² .

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. Hereinafter, “parts” means parts by weight.

(Example 1 )
In a flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 100 parts of isopropyl alcohol, 50 parts of ion-exchanged water, 117 parts of butyl methacrylate, 63 parts of dimethylaminopropylacrylamide as a cationic vinyl monomer, methylenebisacrylamide A monomer mixture obtained by mixing 0002 parts and 1 part of sodium methallylsulfonate was heated to 70 ° C. with stirring under a nitrogen stream, and t-butylperoxy-2-ethylhexanoate (trade name “Perbutyl O "Nihon Yushi Co., Ltd.") 7.2 parts. Further, the temperature was raised to 80 to 90 ° C. and kept for 4 hours. Next, 200 parts of ion-exchanged water and 24.2 parts of glacial acetic acid were added and neutralized, and isopropyl alcohol was distilled off to adjust the solids concentration of the copolymer to 25%, which was used for water-soluble papermaking. A surface sizing agent was used. Table 3 shows the characteristic values of the obtained water-soluble paper surface sizing agent.

(Examples 2 to 5 ) Manufactured in the same manner as in Example 1 except that the amount (mole%) of methylenebisacrylamide which is a crosslinkable monomer component and the chain transfer agent were changed to those shown in Table 1 . Table 1 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Examples 6 to 8 ) Manufactured in the same manner as in Example 1 except that the amount (parts) of the chain transfer agent or the amount (mol%) of the crosslinkable monomer was changed to those described in Tables 1 and 2 . . Tables 3 and 4 show characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Example 9 )
Except that the amounts (mol%) of (meth) acrylic acid ester monomer component butyl methacrylate and cationic vinyl monomer component dimethylaminopropylacrylamide and methylenebisacrylamide were changed to those shown in Table 2 , Examples 1 was produced in the same manner. Table 4 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Example 10 ) Manufactured in the same manner as in Example 1 , except that styrene was used in combination as another optional copolymerizable monomer, and the amount of each component used was changed to that shown in Table 2. Table 4 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Example 11 ) In a flask equipped with a stirrer, a condenser tube, a nitrogen introduction tube and a thermometer, 100 parts of isopropyl alcohol, 50 parts of ion-exchanged water, 117 parts of butyl methacrylate, 63 parts of dimethylaminopropylacrylamide, methylenebisacrylamide A monomer mixture obtained by mixing 019 parts and 1 part of sodium methallylsulfonate was heated to 70 ° C. while stirring under a nitrogen stream, and t-butylperoxy-2 ethylhexanoate (trade name “Perbutyl O 7.3 parts of “Nippon Yushi Co., Ltd.” was charged. Further, the temperature was raised to 80 to 90 ° C. and kept for 4 hours. Next, 200 parts of ion-exchanged water and 24.2 parts of glacial acetic acid were added and neutralized to distill off isopropyl alcohol, and then 37.4 parts of epichlorohydrin (quaternizing agent) was added at 60 ° C. It reacted for 3 hours and adjusted so that solid content concentration might be 25%, and this was made into the surface sizing agent for water-soluble papermaking. Table 4 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Example 12 )
In a flask equipped with a stirrer, condenser, nitrogen inlet tube and thermometer, 98 parts of isopropyl alcohol, 49 parts of ion-exchanged water, 125.1 parts of butyl methacrylate, 41.8 parts of dimethylaminopropylacrylamide as a cationic vinyl monomer, anion The monomer mixture obtained by mixing 15.1 parts of 80% acrylic acid, 0.02 part of methylenebisacrylamide and 1 part of sodium methallylsulfonate as a reactive vinyl monomer was heated to 70 ° C. while stirring under a nitrogen stream. 7.3 parts of t-butylperoxy-2 ethylhexanoate (trade name “Perbutyl O” manufactured by NOF Corporation) was charged. Further, the temperature was raised to 80 to 90 ° C. and kept for 4 hours. Next, 200 parts of ion-exchanged water and 16.1 parts of glacial acetic acid were added and neutralized, and isopropyl alcohol was distilled off to adjust the solid content concentration to 25%, which was used as a water-soluble surface sizing agent for papermaking. It was. Table 4 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Comparative Example 1 ) Production was carried out in the same manner as in Example 1 except that methylenebisacrylamide and the chain transfer agent sodium methallylsulfonate were not used. Table 5 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Comparative example 2 ) It manufactured like Example 1 except not having used a methylenebisacrylamide. Table 5 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

(Comparative Examples 3 and 4 )
Example 1 except that the amount of methylenebisacrylamide, which is a crosslinkable monomer component, was changed to 0.008 mol%, and the amount of sodium methallyl sulfonate as a chain transfer agent was changed to that shown in Table 3. Manufactured. Table 5 shows the characteristic values of the obtained water-soluble surface sizing agent for papermaking.

Below, the measuring method of the characteristic value of the water-soluble paper surface sizing agent obtained by each Example and the comparative example is demonstrated.
In Comparative Example 3 , since the obtained copolymer was gelled, the characteristic value could not be measured.
(Molecular weight)
Examples 1 12 surface sizing agent Examples 1 to 12 obtained in Comparative Examples 1 to 4, a surface sizing agent obtained in Comparative Examples 1 to 4 (cationic vinyl monomers, and anionic vinyl monomers and cationic For those using a vinyl monomer in combination, the weight average molecular weight was measured as a polystyrene equivalent value by gel permeation chromatography (Shodex GPC system-21H, columns used GF-7M, GF-310, developing solvent DMF).
(viscosity)
The product was put into a 225 ml mayonnaise bottle and measured using a B-type viscometer at 25 ° C.

A coating solution was prepared using each of the water-soluble surface sizing agents obtained as described above, and this was applied to uncoated paper, and the size effect and foaming performance were tested.
In Comparative Example 3 , since the obtained copolymer was gelled, the following test could not be performed.
(Performance test of surface sizing agent)
Apply sizing agent, starch (trade name “Oji Ace A”, manufactured by Oji Cornstarch Co., Ltd.) and sodium chloride as inorganic salts in a ratio of 0.4: 5.0: 1.0 (weight ratio). A working solution was prepared. Next, uncoated neutral high-quality base paper (basis weight 65 g / m ² , steecht size degree 5 seconds) is prepared, and the coating liquid is applied to one side with a bar coater at a liquid absorption of 12 g / m ² . The coated paper was dried by passing through a rotary drum dryer at 105 ° C. for 1 minute and subjected to the following performance test.

(Stick human sizing degree)
The sized sizing degree (seconds) of the coated paper subjected to the size treatment was measured according to JIS P-8122. The larger the value, the better the sizing degree.
(Pen writing size)
Regarding the coated paper subjected to the size treatment, J. Org. Tappi No. 12 was used to measure the pen writing size. The larger the value, the better the sizing degree.
(Foaming)
250 g of the coating liquid heated to 40 ° C. was put into a home mixer having a capacity of 1250 ml and stirred for 1 minute. After the mixer stopped, the foam height immediately after was measured. The smaller the value, the lower the foamability. In addition, the bubble height before the process of a coating liquid was 70 mm.
The test results of the above sizing agent characteristics and size performance are shown in Tables 1 to 5.

Claims (5)

A monomer component containing a (meth) acrylic acid ester monomer component , a cationic vinyl monomer component, and a crosslinkable monomer component having a plurality of radically polymerizable functional groups in the molecule, is added in an amount of 0.01 to 100 parts by weight of the total monomer components. A water-soluble surface sizing agent for papermaking containing a copolymer obtained by copolymerization in the presence of -20 parts by weight of a chain transfer agent. Total monomer component (meth) acrylic acid ester monomer component is 40 to 85 mol%, Ca thione vinyl monomer component is 14 to 59 mol%, crosslinking monomer component having a plurality of radically polymerizable functional groups in a molecule 0. The surface sizing agent for papermaking according to claim 1, containing 0001 to 10 mol%. The chain transfer agent is represented by the general formula (1)

The surface sizing agent for papermaking according to claim 1 or 2, wherein R is a compound of (wherein R is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 8). The paper-making surface size according to any one of claims 1 to 3, wherein the crosslinkable monomer component having a plurality of radically polymerizable functional groups in the molecule is bis (meth) acrylamides and / or di (meth) acrylic esters. Agent. The surface sizing agent for papermaking according to any one of claims 1 to 4, wherein the copolymer has a weight average molecular weight of 5,000 to 500,000.