JPH0425569A - Coating composition for lustering paper - Google Patents

Abstract

PURPOSE:To obtain the tittle comps. which gives a printed paper an aesthetic appearance and luster, protects the printed surface, and is excellent esp. in blocking resistance and crushability by copolymerizing a fluoroalkylated or perfluoroalkylated unsatd. carboxylic ester with other monomers. CONSTITUTION:1-40wt.% fluoroalkylated or perfluoroalkylated carboxylic ester, 5-60wt.% styrene, 30-80wt.% methyl methacrylate, 1-30wt.%, alpha,beta-unsatd. carboxylic acid, and 0-50wt.% other vinyl monomer copolymerizable with the foregoing monomers are copolymerized to give a copolymer having a second order transition point of 70-95 deg.C. From the copolymer and an org. solvent is prepd. the title compsn., which is used for giving a printed paper an aesthetic appearance and luster and for protecting the printed surface and is excellent esp. in blocking resistance and crushability.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a coating composition for polishing paper for the purpose of imparting beauty and gloss to printed paper and protecting the printed surface. This invention relates to a coating composition that has excellent blocking properties and blistering properties.

[Prior art and problems to be solved by the invention 1 Paper polishing processing involves two types of paper polishing: a free-painting type in which paint is applied to the lithographically printed paper surface and then dried, and a press in which a hot press is applied using a mirror plate after application. There are different types, but as products become more sophisticated, pressed types have become mainstream. Immediately after press processing, paper is stacked and stored with the processed and non-processed sides facing each other, and after being formed into the cover of a box or book, the processed and processed sides are facing each other. They are stored in piles on top of each other.

Therefore, the blocking resistance when the processed surface and the unprocessed surface, and the processed surface and the processed surface are stacked facing each other, is determined by the mold releasability,
Along with blistering properties, this is an essential characteristic requirement for resins used in polishing paints.

The term "blubbling" here refers to the phenomenon that occurs during press processing, where the paint resin is roll-coated onto the surface of printing paper and the coating surface is pressed with a mirror plate to improve the smoothness of the paper surface. This is a characteristic that promotes smoothing. Even after being pressed, if the peeling resistance is low, depressions remain on the coating surface and the paper surface appears white and blurred, which is called a peeling defect.

Conventionally, methods have been used to improve blocking resistance, such as raising the secondary transition temperature of the resin, increasing the resin molecular weight, blending or graft copolymerizing cellulose derivatives, and adding silicone-based additives. The corresponding method has been known as a publicly known method.

However, JP-A-55-25455 and JP-A-55-22079
The secondary transition temperature of the resin is relatively high as described in 8.
If only the temperature is set at 0 to 100°C, it is impossible to completely and simultaneously satisfy the recent market's strict demands for anti-blocking properties and resistance to crushing due to endless press.

When a cellulose derivative is blended with a resin, all but the resin having a very limited composition will separate.
Furthermore, in JP-A-59-100794, graft copolymerization of cellulose derivatives to acrylic resins has been studied, but this measure results in a lack of both gloss and blistering properties, and if sufficient resistance is not achieved, If copolymerization is carried out to the extent that blocking properties are developed, in order to obtain a viscosity suitable for painting, the paint must have a low solid content concentration of 30% or less, resulting in a decrease in painting workability. is unavoidable.

In addition, if the molecular weight of the resin is increased, this is also not preferred since the solids concentration must be lowered in order to obtain a viscosity suitable for coating.

Furthermore, many of the additives intended to improve blocking resistance bleed onto the surface of the coating film after polishing, deteriorating its appearance.

[Means for Solving the Problems] The above problems are solved by adding fluoroalkyl group- or perfluoroalkyl group-containing acrylic esters or similar methacrylic esters to known resin compositions for paper polishing. It has been found that the problem can be solved by copolymerizing the vinyl monomer used.

To explain in more detail, this invention provides (on a weight basis)
a) 1 to 40% of unsaturated carboxylic acid ester containing a fluoroalkyl group or perfluoroalkyl group, (b) 5 to 60% of styrene, (c) 30 to 30% of methyl methacrylate
80%, (d) 1 to 30% of α,β unsaturated carboxylic acid, and (e) 0 of other vinyl monomers copolymerizable with these.
It is a coating composition for paper polishing consisting of a copolymer and an organic solvent, which are obtained by copolymerizing ~50% of the copolymer and whose secondary transition temperature is in the range of 70 to 95°C.

The copolymer for the resin composition used in this invention is obtained by copolymerizing the above (a), (b), (c), (d), and (e), among which ( a
) Specifically, the unsaturated carboxylic acid ester containing a fluoroalkyl group or a perfluoroalkyl group has a hydrogen atom substituted with a fluorine atom and has 1 or more carbon atoms, preferably 1 to 1B carbon atoms. A compound having a fluoroalkyl group or a perfluoroalkyl group in the alcohol residue, and is used in an amount of 1 to 40% by weight based on the total composition of the constituent monomers of the copolymer. If the amount is less than 1%, the blocking resistance will be insufficient, and if it exceeds 40%, the adhesion to the base hand-printed surface will deteriorate, which is undesirable.

Specific examples of these include C, H2=CHCOOCH2
CF3, CI(2=C(C)13)COOCI(2CF
3, CH2=CHC00CH2CF, CHF2, C
H2”C(C)+3) C00CF 2CHF2,C)
I2=CHCOOCH(CH3) C2F6, CH2=
C(CH3) COOCH2(CHa) C2F5,C
H2・C)ICOOC)I (CF312, CL=C(
CH3) C00CH(CF3) 2, CH2=CHC
00C1(2CF2CHFCF3, CHa=C(CH3
) C00CH2CF 2CHFCF3, CH2=CH
C00C1(-(CH3)C3F7, C2H=C(C)
+3) C00CI ((CH3) C3Fff, C) I
2:C-C00CH2(CFa) 4)1'%H3 CHz=C-COOCH2(CF2)4)1,HCH3 Cth=C-C00CH2CFrs 't CH2''C
-C00C)12c7FI5,HC5H7 CHz=C-COOCH2-CHzNO2SCaF+□
CH3C5H7 CH2=C-COOC)12-CH2NO□5CIIF
178 CH3 C)+2=C-COOCH2-CH2NO□5CaF1
tCH3CH3 CHz:C-C00CL-CHzNO□5C1lFI7
CH2”C-C0D-CH2-CH2C8F+3,
CH3CL=C-COOCL-CL-CaF13, HC)
l.

CH2=C-C00C)+2-CH2-N02S-CF
2-CF2CH3CH3 CH2=C-C00CH2-CH2-No□5-CFz
-HC2Hs CI-12=C-COOCH2-CH2-NCDC,F
,5CH3C2H3 C)1z=C-COOC)12-CHzNCOC7F+
5CH2・CHOCI(2-CH2(CF2) 9CF
3CH2=C-C0O-(CH2) zcaF+□H3 CH2=C-COD-(CH2)11 C3F17H
3C)12=C-COOC)12c8F,.

C) 12=c-COOC) 12c8F, □H0H C) Iz=C-COOCHz-CH-CH2-CaF+
tC)13DI-1 CL=C-COOCL-CH-CL-CaF17■ CHz=C-COO(CHz) 5OcF (CF3)
2HCH3 CH3 CL=C1l-CHJOC(CL) 1ONO23C8
F+7, 2H5 C4H300C-CH=C)1-COD-C)12-C
H2NO□SC,F,? , C4H80OC-CH”
CH-COOCHzCaF l7, or C3H70
0C-CH=CHCOOCtlzC4Fs, etc.
These are prepared by reacting a fluorinated alcohol with a linear, branched, or cyclic chain with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or an acid chloride thereof, or by reacting a fluorinated alcohol with a linear, branched, or cyclic chain. Fluorinated alkanecarboxylic acids having a cyclic chain or their acid chlorides and β-hydroxyethyl acrylate or β
- Hydroxyethyl methacrylate, β-hydroxypropyl acrylate, reaction with a hydroxyl group-containing vinyl monomer such as β-hydroxypropyl methacrylate, or ethylene chlorohydrin adduct of fluorinated alkanesulfonic acid amide and acrylic acid. or an unsaturated carboxylic acid such as methacrylic acid, or an acid chloride thereof. Of course, these may be used alone or as a mixture of two or more.

Component (b) Styrene is an essential component for giving gloss to the coating film, and if the content is less than 5%, the gloss will be too low.
If it exceeds 60%, the releasability from the press plate and the wear resistance will be insufficient.

The copolymerized amount of styrene is preferably 10 to 40% by weight.

Component (c), methyl methacrylate, is an essential component for imparting wear resistance and mold releasability from the press plate to the coating film. If the content is less than 30%, these properties are insufficient. If it exceeds 80%, it is not preferable because it requires a low solid content concentration in order to obtain a viscosity suitable for coating.

The α,β-unsaturated carboxylic acids of component (d) include monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid, and dibasic acids such as fumaric acid, maleic acid, and itaconic acid. If the content is less than 30%, the adhesion to paper and drying properties will be insufficient, and if it exceeds 30%, the viscosity of the copolymer solution will increase, making it difficult to make the viscosity suitable for painting. However, this is not preferable because the coating must have a low solids content.

Other vinyl monomers that can be copolymerized with these component (e) mainly have a secondary transition temperature of the copolymer of 70 to 95°C.
and/or to impart adhesion and abrasion resistance, and any monomer has one or more polymerizable vinyl groups. Tea'C is also good. Examples of the vinyl monomer include acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms, methacrylic acid alkyl esters (hereinafter collectively referred to as "(meth)acrylic acid alkyl esters"), vinyl group-containing aromatic compounds,
Or a monofunctional vinyl compound that can be copolymerized with both of these, or a polyfunctional vinyl compound that can be copolymerized with these monofunctional vinyl compounds and can undergo a crosslinking reaction.

Specific examples of (meth)acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms include methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 1-butyl (meth)acrylate, t
-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. A specific example of the vinyl group-containing aromatic compound is a-methylstyrene. Examples of other vinyl monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate,
Examples include vinyl acetate, vinyl propionate, (meth)acrylonitrile, and the like.

The method of polymerizing the monomers (a) to (e) is not particularly limited, but solution polymerization provides the desired polymer of high quality and is also economically advantageous.

The polymerization initiator is also not particularly limited, and examples include azo initiators such as azobisisobutyronitrile, and peroxide initiators such as benzoyl peroxide. Furthermore, a chain transfer agent such as n-dodecyl mercaptan may be used to control the molecular weight during polymerization. As the solvent, toluene, xylene, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, improper tool, etc. are used, and the monomer concentration during polymerization is 30% to 70%. Less than is preferred. The reaction temperature is determined by the decomposition temperature of the initiator and the boiling point of the solvent.
The temperature is selected within the range of 65°C or more and less than 110°C. The reaction time is appropriately selected depending on the monomer composition, polymerization method, polymerization temperature, etc. The dose of initiator relative to the total amount of monomers is within the range of 0.005% or more and less than 5%.

The dose of chain transfer agent relative to the total amount of monomers is 0.05
% or more and less than 5%.

If the secondary transition temperature of the copolymer is less than 70°C, mold releasability,
and lack of blocking resistance.

On the other hand, if the temperature exceeds 95°C, the brittleness is insufficient.

The organic solvent used in this invention may be any known organic solvent conventionally used in paper polishing coatings, such as toluene, xylene, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, Examples include ethanol, isopropanol, and others. These may be used alone or in combination of two or more. The ratio of copolymer to organic solvent is copolymer/organic solvent = 60/40 to 25/75.
Preferably, it is selected in the range of 50,150 to 40/60.

[Example] The present invention will be explained in more detail by showing Examples and Comparative Examples below. In addition, all "parts" in Examples and Comparative Examples indicate "parts by weight."

Example 1 50 parts of toluene, 30 parts of isopropyl alcohol, 40 parts of methyl methacrylate, 30 parts of styrene, 10 parts of methacrylic acid, 10 parts of pentadecafluorodecyl methacrylate, 10 parts of n-butyl methacrylate, and 02 parts of azobisisobutyronitrile were charged, the temperature was raised to 90°C, and after polymerization for 2 hours, the reaction temperature was raised to 90°C. A solution consisting of 12 parts of azobisisobutyronitrile and 40 parts of toluene was added dropwise over a period of 4 hours, and then stirred and heated at 90°C for 2 hours to increase the conversion rate to resin. Later, 10 parts of toluene and 20 parts of isopropyl alcohol were added to terminate the reaction.

The obtained copolymer solution was colorless and transparent, and its solid content was 405%.

This solution was diluted with toluene to a solids content of 35%, and 2 parts of lecithin, based on the solids content, was added as a mold release agent.

This is lithographically printed cardboard with a coating thickness of 3 when dry.
It was coated with a bar coater so that it had a thickness of μm, dried for 10 minutes at room temperature, and then coated with an endless press at 110°C, 200 kg/cm2.20 m/
Pressed under conditions of min.

Table 2 shows the crumbling resistance and anti-blocking properties and other properties of the processed paper thus obtained.

Examples 2 to 7 and Comparative Examples 1 to 4 These were operated in the same manner as in Example 1, and the monomer compositions were as shown in Table 1.
It was carried out as shown in .

In both cases, the solids content in the solution after polymerization was 40
It was 1%. The crumple resistance, anti-blocking properties, and other properties of the resulting processed paper are shown in Table 2.

[Effects of the Invention] As clearly recognized from the Examples and Comparative Examples, the present invention shows that an unsaturated carboxylic acid ester containing a fluoroalkyl group or a perfluoroalkyl group can be used in a known paper polishing resin composition. By using a coating composition for paper polishing that is produced by copolymerizing with vinyl monomers, we have achieved resistance to blistering, blocking, and abrasion by endless press, which were not achieved with conventional technology. For the first time, a processed paper that satisfies the requirements for gloss, adhesion, and mold release properties has been obtained for the first time.

Below is a list of abbreviations in Table 1.

MMA: t -BMA AA -BA -EHA MA A Methyl methacrylate styrene n-butyl methacrylate methyl acrylate ethyl acrylate n-butyl acrylate 2-ethylhexyl acrylate lauroyl methacrylate itaconic acid methacrylic acid acrylic acid C)+2=C(CH3) C00CH2CF3CH2=
C(CH3)C00CR(CF31 C3F7+7FA
: 17 parts M : C1(2=C-COD (CL) 2CaF + 7H
3 CH2=C-COO(CH2) 2C8F+7 The following are evaluation and measurement methods such as Examples.

Blistering property: Confirmed by visual observation after breathing.

Wear resistance: The load was 500 using a Gakushin type abrasion tester.
Check the surface condition with the naked eye after 20 reciprocations as g.

Adhesion: According to a peel test using Nichiban Sellotape 6, there was no peeling between the hand-printed surface and the glossy paint surface, and ○ was determined, while peeling was observed.

Mold release property: ○ indicates that the paper peels off from the press plate due to its own weight near the delivery roll, ・ indicates that it does not peel off.
And so.

Blocking resistance: 4 cm square pieces of paper were placed one on top of the other with the printed side facing the printed side and the printed side facing the non-printed side, and held under a load of 3 kg in an environment of 60°C and 80% humidity for 18 hours. Those that can be removed without breaking are ○.
It was said that it was impossible.

Gloss: According to JIS Z 1640.

Tg (secondary transition temperature) : Actual measurement using silatometry method.

Claims (1)

[Scope of Claims] (a) 1 to 40% by weight of an unsaturated carboxylic acid ester containing a fluoroalkyl group or a perfluoroalkyl group
, (b) 5-60% by weight of styrene, (c) 30-80% by weight of methyl methacrylate, (d)
1 to 30% by weight of α,β unsaturated carboxylic acid, and (e) 0 to 50% of other vinyl monomer copolymerizable therewith.
It is obtained by copolymerizing % by weight, and has a secondary transition temperature of 70 to 9.
A coating composition for paper polishing comprising a copolymer having a temperature of 5°C and an organic solvent.