JPH04328112A - Production of varnish for paint - Google Patents

Abstract

PURPOSE:To obtain a product giving a coating film having excellent solvent resistance and water resistance by using a specific polymerization initiator in the polymerization of a hydroxyalkyl (meth)acrylate and a (meth)acrylic acid ester. CONSTITUTION:A hydroxyalkyl (meth)acrylate (e.g. 2-hydroxyethyl acrylate) and a (meth)acrylic acid ester (e.g. methyl acrylate) are polymerized in a polymerization solvent in the presence of a polymerization initiator consisting of an organic peroxide of formula (R1 is cyclohexyl; R2 and R3 are 1-9C alkyl) (e.g. 1-methyl-1-cyclohexylethylperoxy-2-ethyl hexanoate). The polymerization is carried out preferably at 100-140 deg.C for 2-10hr.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a paint varnish that provides a coating film with excellent water resistance and solvent resistance.

0002

BACKGROUND OF THE INVENTION Conventionally, methods for producing paint varnishes using specific polymerization initiators have been known. For example, in JP-A No. 63-168415, by using a derivative of t-amyl hydroperoxide as a polymerization initiator, a coating material with a narrow molecular weight distribution, a high concentration of solids, and a relatively low viscosity is used. A method of making a varnish is disclosed.

0003

[Problems to be Solved by the Invention] However, paint varnishes are generally required to have various performances, especially water resistance,
There has been a demand for a paint varnish that can provide a coating film with excellent solvent resistance.

0004

[Means for Solving the Problems] As a result of long-term research into the problems of the above-mentioned conventional methods, the present inventors have developed a paint varnish that solves all of the problems by using a specific polymerization initiator. The present inventors have discovered that the present invention can be obtained, and have completed the present invention. That is, the present invention provides a method for polymerizing one or more hydroxyalkyl acrylates or hydroxyalkyl methacrylates and one or more acrylic esters or methacrylic esters in a solvent using a polymerization initiator. general formula

[Formula 1] (wherein, R1 is a cyclohexyl group, R2, R3
each represents an alkyl group having 1 to 9 carbon atoms.

Examples of the hydroxyalkyl acrylate used in the present invention include 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, and examples of the hydroxyalkyl methacrylate include 2-hydroxyethyl methacrylate and 2-hydroxypropyl acrylate. Examples include propyl methacrylate. Examples of acrylic esters include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, octyl acrylate, and lauryl acrylate. Examples of methacrylic esters include methacrylic acid, methyl methacrylate, and ethyl acrylate. Examples include methacrylate, n-butyl methacrylate, isobutyl methacrylate, octyl methacrylate, and lauryl methacrylate.

[0006] These monomers (hereinafter collectively referred to as polymerization monomers) are used in appropriate combinations depending on the performance required for the product paint varnish, and the proportion of hydroxyalkyl acrylate or hydroxyalkyl methacrylate is as follows: It is used in an amount of 5 to 30% by weight based on the total amount of monomers for polymerization. If it is less than 5% by weight, the adhesion of the paint varnish film of the product will decrease, and if it exceeds 30% by weight,
The physical properties of the coating film deteriorate.

Furthermore, the amount of polymerization monomer used in the paint varnish product is 40 to 70% by weight. If it is less than 40% by weight, the amount of solvent used in the product paint varnish increases, which is economically disadvantageous. Moreover, if it exceeds 70% by weight, the viscosity of the polymer becomes too high, which is not preferable.

[0008] As the organic peroxide used as a polymerization initiator in the present invention, specifically, 1-methyl-1-cyclohexylethyl peroxy-2-ethylhexanoate, 1-methyl-1-cyclohexylethyl Examples include peroxyisobutyrate.

The amount of the polymerization initiator used is 1 to 7% by weight based on the polymerization monomer. Less than 1% by weight,
If the polymerization is not completed and the amount exceeds 7% by weight, the decomposition products of the polymerization initiator will deteriorate the physical properties of the paint varnish coating, which is not preferable.

Examples of the solvent in the present invention include aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; acetate esters such as butyl acetate; alcohols such as n-butyl alcohol. or a mixture thereof.

In the polymerization method of the present invention, the above monomer for polymerization, a polymerization initiator, and a solvent are mixed, and the polymerization temperature is 1.
What is necessary is just to polymerize at 00-140 degreeC for 2-10 hours. If the polymerization temperature is less than 100°C, the polymerization rate will be slow and the average molecular weight of the obtained polymer will be large; if it exceeds 140°C,
It becomes difficult to control the polymerization rate, and both are unfavorable. Furthermore, if the polymerization time is less than 2 hours, it is difficult to control the polymerization heat, and if it exceeds 10 hours, there is no particular advantage and it is economically disadvantageous. Furthermore, in the latter stage of this polymerization reaction, in order to prevent unreacted monomers from remaining in the polymer,
A commonly used polymerization initiator may be added.

At this time, the specific method of mixing the polymerization monomer, polymerization initiator, and solvent is as follows: (1) A mixture of the polymerization monomer, polymerization initiator, and solvent is continuously or intermittently added to an empty polymerization tank. (2) A method in which a mixture of a polymerization monomer and a polymerization initiator is continuously or intermittently added to a polymerization tank containing a solvent while stirring and mixing. (3) A method in which a mixture of a polymerization monomer and a polymerization initiator is stirred and mixed while being added to a solvent. Any method may be used in which the polymerization initiator and the solvent are added simultaneously and simultaneously to the polymerization tank while stirring and mixing. In addition, in these methods, there is no problem even if a part of the polymerization monomer is mixed in advance in the solvent used, or conversely, a part of the solvent is mixed in the polymerization monomer. In these cases,
The mixing ratio of each is determined as appropriate depending on the polymerization apparatus, polymerization conditions, and the like.

[0013]

[Effect of the invention] The method for producing a paint varnish of the present invention makes it possible to produce a paint varnish that can provide a coating film with excellent solvent resistance and water resistance by using a specific polymerization initiator. This makes it possible to meet all the requirements for conventional paint varnishes.

[0014]

[Examples and Comparative Examples] The present invention will be specifically explained below using Examples and Comparative Examples. In addition, in these examples, the abbreviations of the organic peroxide as a polymerization initiator and the monomer for polymerization are as follows. BuO: t-butylperoxy-2-ethylhexanoate (trade name: Perbutyl O, manufactured by NOF Corporation, purity 98%) AmO: t-amylperoxy-2-ethylhexanoate (purity 97%) CyO :1-Methyl-1-cyclohexylethyl peroxy-2-ethylhexanoate (purity 97%) CyI
B: 1-methyl-1-cyclohexylethyl peroxyisobutyrate (purity 97%) BuZ: t-butyl peroxybenzoate (trade name:
Perbutyl Z, manufactured by NOF Corporation, purity 99%) MMA
: Methyl methacrylate BMA: n-butyl methacrylate LMA: Lauryl methacrylate HEMA: 2-hydroxyethyl methacrylate AA:
acrylic acid

Example 1 1 having a dropping funnel, a stirrer, a gas inlet pipe and a reflux condenser
After purging the inside of the 000 ml four-necked flask with nitrogen gas, 300 g of xylene was added, and from the dropping funnel BMA/LMA/HEMA/AA (40 g) was added as a polymerization monomer.
/40/18/2 (weight ratio)) and 18 g of CyO as a polymerization initiator were heated at 130°C for 5 minutes.
It was dropped at a uniform speed over time. Thereafter, 4.5 g of BuZ was added to remove unreacted monomers, and the reaction was continued at 130° C. for 2 hours to obtain 770 g of a viscous solution. Regarding this viscous solution, first, the amount of unreacted monomer was measured by gas chromatography to determine the polymerization conversion rate, and then the viscosity was measured using a B-type viscometer. Furthermore, to 100 g of viscous solution,
50 g of xylene, 10 g of n-butanol, melamine curing agent (product name: Cymel 370, manufactured by Mitsui Toatsu Chemical Co., Ltd.)
After 10 g of the mixture was mixed and spray coated on a 70 x 150 mm steel plate, it was dried at 150°C for 30 minutes to form a coating film, which was used as a test piece. This test piece was immersed in toluene, left at room temperature for one week, and then dried at 100° C. for one hour.The weight of the coating film before and after dipping was compared to determine the amount of coating film eluted. Next, the clarity of the coating film before and after dipping was comparatively evaluated by the following method. That is, 10 with a diameter of 5 to 10 mm.
A piece of cellophane tape with "○ marks" printed on it showing the size of each step was attached to a fluorescent lamp, and it was reflected on the coating film of the test piece to evaluate which step size could be determined. The sharpness of the image is high enough that it can be distinguished, and the measured value is set to be a large value). The results are shown in Table 1.

Example 2, Comparative Examples 1 and 2 Polymerization was carried out in the same manner as in Example 1, except that the polymerization initiators shown in Table 1 were used instead of 18 g of CyO. The results are shown in Table 1.

Examples 3 and 4, Comparative Example 3 In Example 1, BMA/
Instead of LMA/HEMA/AA (40/40/18/2 (weight ratio)), MMA/BMA/HEMA/AA (
A viscous solution was obtained according to Example 1, except that 43/40/15/2 (weight ratio) was used. Next, 100 g of this viscous solution was mixed with 50 g of xylene and 10 g of n-butanol, and the mixture was spray coated on a 70 x 150 mm steel plate, and then dried at 150° C. for 30 minutes to form a coating film to prepare a test piece. This test piece was immersed in boiling water, left for 5 hours, and then dried at 100°C for 1 hour.The weight of the coating film before and after immersion was compared to determine the amount of coating film elution, and the sharpness of the coating film was determined. was measured. The results are shown in Table 1.

[0018]

[Table 1] As is clear from the results in Table 1, in Examples 1 and 2 using the polymerization initiator of the present invention, compared with Comparative Examples 1 and 2 using the conventional polymerization initiator, It can be seen that the amount of coating film eluted when immersed in an organic solvent was small, and furthermore, there was no deterioration in the sharpness of the coating film before and after immersion. On the other hand, in Examples 3 and 4 in which the polymerization initiator of the present invention was also used, the amount of coating film eluted when immersed in boiling water was smaller than in Comparative Example 3 in which a conventional polymerization initiator was used. It can also be seen that there is no deterioration in the sharpness of the coating film before and after dipping. From the above, it is recognized that by using the polymerization initiator of the present invention, a coating film having excellent solvent resistance and water resistance can be obtained.

Claims (1)

[Claims] Claim 1: In polymerizing one or more hydroxyalkyl acrylates or hydroxyalkyl methacrylates and one or more acrylic esters or methacrylic esters in a solvent using a polymerization initiator, generally used as a polymerization initiator. A coating material characterized by using one or more organic peroxides represented by the formula [Formula 1] (wherein R1 represents a cyclohexyl group, and R2 and R3 each represent an alkyl group having 1 to 9 carbon atoms) How to make varnish.