JPS5836120B2 - Kamihi Fukuyouso Saibutsu - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improved paper-covered kumikaimono.

More specifically, at least one surfactant selected from the group consisting of polyoxyethylene alkyl (allyl) ether phosphate esters or alkali salts thereof is used as a polymerization emulsifier or stabilizer. Synthetic copolymer latex produced from a mixture of group conjugated diolefin, acrylic acid or acrylic acid and fumaric acid, and other monoolefinic monomers in which 80% or more is styrene and or methyl methacrylate that can be copolymerized with these. This is a paper coating composition containing as the main pigment binder excellent water resistance, adhesiveness, and printing ink receptivity during offset printing.

Conventionally, many polymer latexes such as butadiene-styrene-ethylenically unsaturated carboxylic acid copolymer and butadiene-methyl methacrylate ethylenically unsaturated carboxylic acid copolymer have been widely used in the pigment coating process of paper. However, due to the rising prices of natural products such as casein, which are used in conjunction with these synthetic copolymer latexes, the amount of these products has been reduced, and processed paper and paper that can be adapted to printing technology that is becoming more sophisticated are being developed. The need for a water-dispersed compound for paper coating that is compatible with paper coating machines, which are becoming faster, has required improvements in the performance of conventional synthetic copolymer latexes.

As a result of various studies on improving the performance of conventional synthetic copolymer latex, the present inventors discovered that aliphatic latex using polyoxyethylene alkyl (allyl) ether phosphate ester surfactant as an emulsifier or stabilizer. Conjugated diolefin 25-59.5% by weight, 0.5-10% by weight of acrylic acid or acrylic acid and fumaric acid, 40-74.5% monoolefin monomer of which 80% or more is styrene and/or methyl methacrylate A composition for paper coating in which a polymer latex consisting of a weight φ has significantly improved water resistance, adhesion, and printing ink receptivity during offset printing compared to conventional synthetic copolymer latex for paper coating. It was discovered that it has revolutionary performance.

Generally, coated papers or pigment binders are required to have the following properties.

Usually, casein starch or its modified product, polyvinyl alcohol, etc. are used together with polymer latex as a pigment binder, but since these pigment binders are water-soluble or water-dispersible compounds, the resulting coated paper Since the water resistance decreases, a water resistance agent is further used to improve the water resistance of the coated paper.

However, the amount of water-resisting agents that can be used is limited because they are generally expensive and have a formalin odor, so it is desirable to provide coated paper with a higher degree of water resistance using polymeric or copolymer latex itself. It is rare.

In general, modified rosin salts, higher fatty acid salts, alkylbenzene sulfonates, etc. are used as emulsifiers during the production of Gokai copolymer latex, but these emulsifiers are highly hydrophilic and are waterproof to coated paper. This is not desirable as it often reduces performance.

In order to improve this drawback, there are examples of using alkyl phosphate ester type surfactants.

However, alkyl phosphate type surfactants have a slow emulsion polymerization rate and are not preferred from an economic standpoint.

Furthermore, in the case of polymerization under acidic conditions, this tendency is particularly marked, and the polymerization is not suitable for the polymerization of the monomer composition of the present invention.

On the other hand, coated paper has adhesive strength that can withstand advanced printing,
Water resistance (wet adhesive strength) to withstand offset printing, and printing ink receptivity to enable beautiful printing are required.

Accordingly, an object of the present invention is to provide a coated paper that is suitable for high-speed printing and multicolor offset printing and has excellent water resistance and print receptivity.

According to the invention, aliphatic conjugated diolefins 25-59.
5% by weight of acrylic acid or 0.5-10% by weight of acrylic acid and fumaric acid, 40-74.5% by weight of a monoolefin monomer of which at least so% is styrene and/or methyl methacrylate. The mixture is prepared using a bifurcated formula (wherein R is an alkyl or alkylaryl group having 6 to 18 carbon atoms, n is a number of moles of ethylene oxide added with 1 to 10 carbon atoms, and the number is a hydrogen atom or other monovalent cation atom or The atomic group, B, is a hydrogen atom or other monovalent cation atom or atomic group, or R{-OCH2CH2+n.

) A polymerization or copolymer obtained by emulsion polymerization using at least one surfactant selected from phosphoric esters of polyoxyethylene alkyl (allyl) ethers or alkali salts thereof as an emulsifier, the main component being a compound represented by A combined latex or a latex obtained by emulsion polymerization of the above latex with a conventional emulsifier, if necessary, and a combined copolymer latex obtained by adding the above surfactant as a stabilizer, and casein starch or its modification. A paper coating composition comprising a pigment binder such as polyvinyl alcohol is provided.

Among the monomer mixtures used in the production of the polymerization or copolymer latex of the present invention, aliphatic conjugated diolefins include butadiene, isoprene, and the like.

Generally, these monomers are used in a weight range of 25 to 59.5 in order to impart appropriate elasticity to the copolymer.

Acrylic acid or acrylic acid and fumaric acid improve adhesion and improve the mechanical stability of the resulting latex.

Furthermore, it reacts with commonly used waterproofing agents to create a crosslinked structure, which helps improve water resistance.

These acrylic acid or acrylic acid and fumaric acid are used in an amount of 0.5 to 10 weight φ based on the total monomers.

Monoolefin monomers that can be copolymerized with these include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, methyl acrylate,
Alkyl acrylate monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, etc. Examples include alkyl methacrylate monomers such as acrylamide, acrylonitrile, etc., but these are easily copolymerized with the above aliphatic conjugated diolefin and acrylic acid or acrylic acid and fumaric acid, and more than so% is styrene. and/or methyl methacrylate.

Further, these monomers are used in an amount ranging from 40 to 74.5% by weight of the total monomers.

In order to achieve the purpose of the present invention and exhibit the characteristics of the paper coating composition of the present invention, an essential component is a phosphate ester of polyoxyethylene alkyl (allyl) ether or an alkali salt thereof. An activator, which is used as a so-called emulsifier during polymerization or added as a stabilizer to the polymerization or copolymer latex.

The polyoxyethylene alkyl (allyl) ether phosphate ester or its alkali salt surfactant is a compound represented by the general formula.

In the formula, R is an alkyl or alkylaryl group having 6 to 18 carbon atoms, n is the number of moles of ethylene oxide added from 1 to 10, A is a hydrogen atom or a monovalent cation atom or atomic group,
B represents a hydrogen atom, a monovalent cation atom, an atomic group, or R{-OCH2CH2+n.

That is, the compound polyoxyethylene alkyl (allyl) ether phosphoric acid ester or its alkali salt is a monoester or a diester, but it may be a mixture of both.

Conventional anionic surfactants generally used in emulsion polymerization produce a small amount of coagulated product during polymerization and have good storage stability, but have poor chemical stability.

On the other hand, nonionic surfactants have excellent chemical stability, but they produce a large amount of coagulum during polymerization and have poor storage stability.

On the other hand, the copolymer latex using polyoxyethylene alkyl (allyl) ether phosphoric acid ester or its alkali salt used in the present invention is different from the above-mentioned latex using a normal surfactant. It has significantly different properties, ie, it increases the dispersibility with the pigment binder for paper coating, and can exhibit various excellent performances such as water resistance of coated paper, paper surface gloss, and printing ink receptivity.

The synthetic copolymer latex of the present invention is produced by a known aqueous emulsion polymerization method using the above-mentioned surfactant, but a polymerization initiator, a molecular weight regulator, etc. are used as necessary.

The reaction may be carried out by so-called high-temperature polymerization or by low-temperature polymerization using a redox type polymerization initiator, and furthermore, monomers or emulsion stabilizers may be added sequentially during the polymerization as necessary.

The polymer latex thus obtained contains pigments commonly used for paper coating such as china clay, titanium dioxide, satin white, and calcium carbonate, as well as M, such as casein, starch or modified products thereof, and polyvinyl alcohol. It is also used in combination with water-resistant agents such as melamine-formalin resin, urea-formalin resin, polyamide resin, and other agents commonly used for pigment coating.

As is clear from the examples of the present invention, the paper coating composition of the present invention has superior water resistance, adhesion, and printing ink receptivity during offset printing compared to conventional paper coating compositions. ing.

Therefore, it is suitable for high-speed printing and multicolor offset printing.
Furthermore, the surface of the pigment-coated paper and the printed surface are excellent in gloss.

In particular, the composition of the present invention has many advantages over conventional techniques in that it is possible to obtain a coated paper that simultaneously has a high degree of water resistance and good ink receptivity during offset printing. It has excellent usability.

This is because the latex of the present invention has excellent properties.

In other words, when using the latex obtained using the conventional synthetic copolymer latex manufacturing technology, the water resistance is relatively good (
For example, if a latex with better film-forming properties is used, the coated paper will have poor ink receptivity during offset printing. It is generally known that if the formability is worsened or the particle size is increased, ink receptivity during offset printing is improved, but water resistance deteriorates, and the relationship between water resistance and ink receptivity during offset printing is were perceived as contradictory qualities.

This situation was true in the manufacturing technology of pigment-coated paper as well as in the polymerization or copolymer latex, which is one of the raw materials for pigment-coated compositions.

In other words, by increasing the usage ratio of the copolymer latex, which is a binder with greater water resistance than hydrophilic binders such as starch, pigment coating with better water resistance can be achieved as a whole for pigment-coated paper. However, it is generally known that the ink receptivity during offset printing is significantly reduced.

On the other hand, in order to produce pigment-coated paper with good ink receptivity during offset printing, the purpose can be achieved by lowering the proportion of polymer latex used in the binder, but on the other hand, the paper It is known that water resistance is not good.

Under these circumstances, the appearance of the latex of the present invention, which makes it possible to obtain pigment-coated paper that has both high water resistance and excellent ink receptivity during offset printing, has been eagerly awaited by the coated paper manufacturing industry. It was where I was.

By using the latex of the present invention, a pigment-coated paper for offset printing can be obtained which has excellent overall performance that could not be obtained with the prior art, even if it were attempted to be manufactured without considering cost considerations.

Next, the present invention will be explained with reference to Examples, but the present invention should not be limited thereby.

Example 1 36 parts by weight of butadiene, 57 parts by weight of styrene, 4 parts by weight of methyl methacrylate, 1.5 parts by weight of acrylic acid, 1.5 parts by weight of fumaric acid, 0 parts by weight of tertiary dodecylmercabutane
．． A mixture of 4 parts by weight, 0.7 parts by weight of sodium hydrogen carbonate, 1.0 parts by weight of potassium persulfate, 100 parts by weight of water, and an emulsifier were placed in a 1M autoclave, and the mixture was heated to 6 parts by weight while stirring.
A copolymer latex was prepared by reacting at 5° C. for 16 hours.

However, when 0.5 parts by weight of sodium alkylbenzene sulfonate is used as an emulsifier during production, the copolymer latex is used as a copolymer latex, and a phosphate ester of polyoxyethylene lauryl ether (HLB 6.6) (acid value 17) is used as a copolymer latex.
0) The Gokai copolymer latex in the case of using 2.0 parts by weight of (I) is designated as B.

Further, polymerization was carried out using 2.0 parts by weight of HLB (6.6) polyoxyethylene lauryl ester as an emulsifier and the same monomer composition, but a satisfactory latex could not be obtained.

Further, polymerization did not proceed even when a phosphate ester of lauryl alcohol was used.

Also, (I) is added to latex A as a stabilizer.1. The latex to which 5 parts by weight was post-added is designated as C.

Using these latexes A, B, and C and commercially available polymerization or copolymer latexes D and E, a paint for coating paper was prepared according to the following formulation.

Adjust the paints so that the solids content is 45%, and apply the paints to commercially available high-quality paper with a rice weight of 70P using a wire iron so that the dry solids content is approximately 2 (l) per 1m9.
Dry for 2 minutes at 0°C.

The coated paper thus obtained was coated at a surface temperature of 60°C and a pressure of 50k.
Super calender treatment is carried out under the conditions of g/cm and speed of 5 m/min.

Regarding the obtained coated paper, R. The following table shows the results of overprinting several times with a Model 1 printing tester using a commercially available offset printing ink, and measuring the printability and adhesive strength of the pigment based on the degree of destruction of the printed surface.

Wet pick strength indicates the strength to withstand dampening water, and was measured using an RI printing tester.

That is, each strip-shaped specimen is lined up and attached to a mount, and after a certain period of time has elapsed after wetting with a well-controlled amount of dampening water. Print it and check the condition of the printed surface.

The evaluation is given as 1 point for a case where the pigment binder did not come off at all and was printed clearly, and 5 points for a case where the pigment binder came off and no printing was done at all.

In addition, the dry pick strength is the pick strength when no dampening water is used, and like the wet pick strength, R
It was measured using a printing ink with a high tack value using an I printing tester, and the determination was also expressed using the same numerical display method.

Ink receptivity during offset printing is determined by using a test paper prepared in the same way as when measuring wet pick strength, using a well-controlled amount of dampening water, and immediately printing using a printing ink with a low tack value. The degree of ink acceptance was visually judged, and a score of 1 was given for a print that was well printed without being affected by dampening water, and a score of 5 was given for a paper with extremely poor ink acceptance.

As is clear from the results in Table 1, when a phosphate ester of polyoxyethylene alkyl (allyl) ether is added later as a stabilizer, the wet pick strength of C does not change, but the ink receptivity improves.

Further, when B is used as an emulsifier during polymerization, the wet pick strength is improved, and the ink receptivity during offset printing is much better than that of conventional synthetic copolymer latexes.

Comparative Example A and commercially available Rakkutsu D have relatively good wet pick strength, but poor ink receptivity during offset printing, and Comparative Example E has relatively good ink receptivity during offset printing. Yes, but the wet pick strength is very poor.

Example 2 In the same manner as in Example 1, copolymer latexes having compositions and proportions as shown in Table 2 were produced.

Using these five synthetic copolymer latexes, a paper coating paint was prepared according to the pigment binder formulation of Example 1, and the resulting coated paper was subjected to various printability tests in the same manner as in Example 1. The results are shown in Table 3.

As is clear from the results in Table 3, polyoxyalkyl (
By using phosphoric acid ester of (allyl) ether, a breakthrough in water resistance, adhesion, ink receptivity, and gloss of the printed surface of coated paper, which could not be achieved with conventional polymeric or copolymer Latinx. It can be seen that it has excellent performance.

Claims (1)

[Scope of Claims] 1 General formula (wherein R is an alkyl or alkylaryl group having 6 to 18 carbon atoms, n is the number of moles of ethylene oxide added from 1 to 10, and A is a hydrogen atom or other monovalent group) Polyoxyethylene alkyl (allyl) represented by a cation atom or atomic group, B is a hydrogen atom or other monovalent cation atom or atomic group, or R {-OCH2CH2+n.
Aliphatic conjugated diolefins 25 to 59 obtained by using at least one surfactant selected from the group consisting of ether phosphoric esters or their alkali salts as a polymerization emulsifier or emulsion polymerization latex stabilizer. .5 by weight, acrylic acid or acrylic acid and fumaric acid 0.
5-10 Monoolefin monomer 40 whose weight ratio is 80% or more styrene and/or methyl methacrylate
A composition for paper coating, characterized in that it comprises a copolymer latex having a weight of 74.5%.