JPH0214265A - Binder for rotogravure ink - Google Patents

Abstract

PURPOSE:To obtain the title binder obtained by using a specific compound as a diisocyanate compound in production of polyurethanepolyurea resin and capable of providing rotogravure ink having good adhesion to plastic films, etc. CONSTITUTION:The aimed binder consisting essentially of a polyurethanepolyurea resin obtained by subjecting a terminal isocyanate prepolymer obtained by reacting a two-functional polyol with a diisocyanate compound to chain lengthening.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a binder for gravure ink, and more particularly to a binder for gravure ink that provides a gravure ink with good adhesion to plastic films and the like.

(Prior art and its problems) Conventionally, a terminal isocyanate prepolymer obtained by reacting a bifunctional polyol with a molecular weight of 400 to 3,000 with an alicyclic or aliphatic diisocyanate compound has been used as a type of binder for gravure ink. A polyurethane polyurea resin whose chain is extended with diamine is used.

However, when the above-mentioned polyurethane polyurea resin is used as a binder for gravure ink, there is a problem in that the adhesiveness to plastic films and the like is insufficient.

This problem of poor adhesion is caused by the fact that in the production of the polyurethane polyurea resin, the product is not uniform and contains many by-products such as low molecular weight compounds.

That is, conventionally, aliphatic diisocyanate compounds such as hexamethylene diisocyanate compounds have been mainly used as diisocyanate compounds for the above-mentioned polyurethane polyurea resins, so the reaction between the terminal isocyanate prepolymer and the diamine is rapid and the reaction cannot be controlled.

For example, there are two methods for producing polyurethane polyurea resin: one is to add cyanine to a solution of terminal isocyanate prepolymer to obtain the desired product, and the other is to add terminal isocyanate prepolymer to a solution of diamine. Even with the method described above, the reaction between the terminal isocyanate group and the diamine is rapid and difficult to control, making it impossible to obtain a uniform polyurethane polyurea resin.

As a result, adducts in which 2 moles of diamine react with 1 mole of prepolymer, and low molecular weight by-products in which several moles of these adducts are polymerized, are produced, resulting in a non-uniform product.

Therefore, an object of the present invention is to provide a binder for gravure ink which is composed mainly of a polyurethane polyurea resin and has a uniform composition and excellent adhesiveness to plastic films and the like.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a binder for gravure ink whose main component is a polyurethane polyurea resin obtained by elongating a terminal isocyanate prepolymer obtained by reacting a bifunctional polyol and a diisocyanate compound by 3n with a diamine, in which the diisocyanate compound is A binder for gravure ink characterized by being a compound represented by the following formula.

(Function) By employing a specific compound as a diisocyanate compound in the production of polyurethane polyurea resin,
A binder for gravure ink is provided in which the reaction rate of chain extension reaction is controlled, a uniform polyurethane polyurea resin with few harmful by-products is obtained, and a gravure ink with good adhesion to plastic films and the like is obtained.

(Preferred Embodiment) As the bifunctional polyol used in the present invention, any conventionally known polyol can be used, and specifically, ethylene glycol, butanediol, 1,6-hexanediol, 3-methyl-1, Diols such as 5-bentanediol or mixtures thereof and dicarboxylic acids, e.g.
Polyester polyol obtained by reacting adipic acid, sepatic acid, phthalic acid, isophthalic acid, etc.: polytetramethylene glycol, polycaprolactone glycol, polypropylene glycol; alkylene oxide adduct of diol, propylene oxide adduct of bisphenol A; polyester Examples include polyol and polycaprolactone copolymer polyol, valerolatone polyol; monoamine alkylene oxide adduct, oleylamine-propylene oxide adduct, and mixtures thereof. Such bifunctional polyols have a molecular weight of about 400 to 4,000 and an OH value of about 28.
0 to 28 is preferred in the present invention.

The diisocyanate compound to be reacted with the above bifunctional polyol is represented by the above structural formula, and has 1.3
-Bis(α,α-dimethylisocyanatemethyl)benzene (TMXDI) or tetramethylxylylene diisocyanate. This diisocyanate compound may be used alone, or other known diisocyanate compounds,
For example, inphorone diisocyanate (IPDI),
It may be used in combination with hexamethylene diisocyanate (HDI), tolylene diisocyanate ('rDI), xylylene diisocyanate (XDI), water-added XDI, diphenylmethane diisocyanate (MDI), and the like.

The method for producing the terminal isocyanate prepolymer from the above-mentioned bifunctional polyol and the above-mentioned diisocyanate compound may be according to a known method, and can be carried out in an organic solvent or without using an organic solvent, with NCO10H=2:1.2.
(7) This is a method of carrying out an equivalence ratio reaction. Although terminal isocyanate prepolymers with various molecular weights can be obtained depending on the reaction conditions, especially the NGO10H ratio, the preferred molecular weight of the terminal isocyanate prepolymer in the present invention is about 80.
The range is 0 to 8.000, and NC0% is lO to 1
% range.

Any conventionally known diamine can be used as the diamine used for the n-elongation of the terminal isocyanate prepolymer, and preferred specific examples include diaminobenzene, 4,4-diaminodiphenylmethane, and water-added 4.4 -diaminodiphenylmethane, isophorone diamine, hexamethylene diamine, trimethylhexamethylene diamine, 1,3-bis(α,α-dimethylaminomethyl)7-benzene, and the like. The stiff diamine is NC for the terminal isocyanate prepolymer.
O/NH2=0.8: 1. It is preferable to use within the range of O.

Both reactions may be carried out by adding a diamine to the terminal incyanate prepolymer solution, preferably in an organic solvent;
The terminal isocyanate prepolymer may be added to the diamine solvent, or both may be mixed simultaneously.

The reaction conditions are preferably about 15 to 40°C for about 0.5 to 2 hours.

The organic solvent used in the production of the above terminal isocyanate prepolymer and polyurethane polyurea resin includes toluene, methyl ethyl ketone, ethyl acetate, and isopropyl alcohol, or a mixture thereof. However, alcoholic solvents should not be used during the production of the terminal isocyanate prepolymer.

The polyurethane polyurea resin obtained as described above preferably has a molecular weight of about 15,000 to 100,000, and the solution of the obtained polyurethane polyurea resin can be used as it is as a vehicle for gravure ink.

The thus obtained binder for gravure ink of the present invention may be used alone, or may be used in combination with conventionally known binders for gravure ink, such as nitrocellulose, polyamide, acrylic ester, polyvinyl chloride, It can also be used in combination with epoxy resins, cellulose alkyl esters, etc. When used in combination, the polyurethane polyurea resin of the present invention preferably accounts for 30% by weight or more of 9% or more of the total binder.

(Effects) According to the present invention as described above, by employing a specific compound as a diisocyanate compound in the production of polyurethane polyurea resin, the reaction rate of the chain extension reaction is controlled, and the polyurethane resin is produced uniformly and with few harmful by-products. A binder for gravure ink is provided which provides a polyurea resin and provides a gravure ink with good adhesiveness to plastic films and the like.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 Polytetramethylene glycol (08 value 56, molecular weight 2
,000) 1 mol (1,000 parts) m
-TMXD 1 2 mol (244 parts) Tin-based catalyst 062 parts The above components were added and mixed in methyl ethyl ketone at a solid content of 75%, and after reacting for 6 hours at the boiling point of methyl ethyl ketone, methyl ethyl ketone was added to reduce the solid content. It was diluted to 50% to obtain a terminal isocyanate prepolymer. The molecular weight of this terminal isocyanate prepolymer is approximately 2,560,
NC0% was 1.64.

Next, 231.5 parts of isofnalone diamide, 0.25 parts of dibutylamine, 26.6 parts of isopropyl alcohol, and 48 parts of methyl ethyl ketone were placed in a reaction vessel.
While stirring at a temperature of 0°C, 100 parts of the above-mentioned terminal isocyanate prepolymer 50% solution was added, and 50 parts of
The mixture was reacted for 2 hours at a temperature of 60°C to 60°C to obtain a binder for gravure ink of the present invention. The molecular weight of the polyurethane polyurea resin in this was about 43,200.

Example 2 100 parts of the 50% solution of the terminal isocyanate prepolymer obtained in Example 1 was placed in a reaction vessel and heated at 30 to 40°C.
3.15 parts of isophoronediamine while stirring at a temperature of
0.25 parts of dibutylamine, 2 parts of isopropyl alcohol
6.6 parts and 48 parts of methyl ethyl ketone were added and reacted at a temperature of 50 to 60° C. for 2 hours to obtain a binder for gravure ink of the present invention. The molecular weight of the polyurethane polyurea resin in this was 48.400.

Comparative Examples 1 to 6 As the diisocyanate compound of Example 1, isophorone diisocyanate (IPDI) (Comparative Example 1), hexamethylene diisocyanate (1101) (Comparative Example 2)
, tolylene diisocyanate (TDI) (Comparative Example 3),
Xylylene diisocyanate (MDI) (Comparative example 4)
A polyurethane polyurea resin solution of a comparative example was produced in the same manner as in Example 1 except that water-added XDI (Comparative Example 5) and diphenylmethane diisocyanate (MDI) (Comparative Example 6) were used.

Amine equivalents (milliequivalents/1,000g solid content) of the polyurethane polyurea resins of the present invention and comparative examples obtained above
The results were measured as shown below, and the peaks of low molecular weight products analyzed by high performance liquid chromatography were as follows.

Comparative Example 1 IPDI 20-40 2-3 Comparative Example 5 MDI Comparative Example 6 MDI In Comparative Examples 5 and 6, the reaction was too fast to control.

The above results show that only a small amount of free amino groups or blocked amino groups are present in the polyurethane polyurea resin of the present invention, and that the diamine and the terminal isocyanate prepolymer react uniformly.

On the other hand, the polyurethane polyurea resin of the comparative example has a
, and a considerable amount of free amino groups and blocked amino groups were present, indicating that the diamine and the terminal isocyanate prepolymer were not uniformly reacted. Particularly in the case of TDI and MDI, the reaction was rapid and uncontrollable, making it impossible to obtain a satisfactory polyurethane polyurea resin.

Usage Example 40 parts of each of the polyurethane polyurea resins (non-volatile content: 30%) of Examples 1 to 2 and Comparative Examples 1 to 4 were mixed with 30 parts of titanium oxide, 24 parts of toluene, and 6 parts of isopropyl alcohol, respectively. After milling in a ball mill for 20 hours, six types of white gravure inks were prepared, and these inks were used to continuously print on polypropylene film (OPP), polyester film (PET), and nylon film (ONY) using a gravure proofing machine. went. After the printed matter was left for one day, a cellophane tape (width 18 a+m) manufactured by Nichiban ■ was attached to the printed surface, and the tape was strongly peeled off to perform an adhesion test, and the following results were obtained.

For the following clothings, those in which the ink on the printed surface did not come off at all were designated as ◎, those with 80% or more remaining as 0140 to 80% remaining as △, and those with 40% or less remaining as X.

(Margin below)

Claims (1)

[Claims] (1) In a gravure ink binder whose main component is a polyurethane polyurea resin obtained by chain-extending a terminal isocyanate prepolymer obtained by reacting a bifunctional polyol and a diisocyanate compound with a diamine, the diisocyanate compound has the following formula: A binder for gravure ink characterized by being a compound represented by: ▲Contains mathematical formulas, chemical formulas, tables, etc.▼