JPH1160636A - Preparation of acrylic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an acrylic resin which has low viscosity and excellent transparency by using an org. peroxide having a specified structure as a polymn. initiator. SOLUTION: An org. peroxide represented by the formula (wherein R represents a 2-5C alkyl group), or a polymn. initiator compsn. contg. the org. peroxide is used. Org. peroxides represented by the formula usable herein include, e.g. di-t-amyl peroxide, di-t-hexyl peroxide, and bis-1,1,3,3- tetramethylbutyl peroxide. The polymn. initiator compsn. may contain, besides the org. peroxide represented by the formula, other org. peroxide(s) commonly used as a polymn. initiator, and examples of other org. peroxides usable herein include peresters, such as tbutylperoxy 2-ethylhexanoate and t-butylperoxy acetate, and percarbonates, such as t-butylperoxyisopropyl carbonate. The amount of these other peroxides used is about 0 to 100 pts.wt. based on 100 pts.wt. org. peroxide represented by the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an acrylic resin. More specifically, the present invention relates to a method for producing an acrylic resin using an organic peroxide having a specific structure or a polymerization initiator composition containing the same.

[0002]

2. Description of the Related Art Acrylic resins are produced by polymerizing a composition containing a monomer containing (meth) acrylic acid ester as a main component, and are widely used as components of paints and adhesives.

[0003] Organic peroxides are commonly used as polymerization initiators for producing acrylic resins. The polymerization initiator is often selected depending on the polymerization temperature, and when the polymerization temperature exceeds 140 ° C., di-t-butyl peroxide (DTBP) or dicumyl peroxide (D
CP) is widely used. However, DTBP has high volatility and a low flash point, so care must be taken in handling. Also, DCP has an aromatic ring in its chemical structure,
In order to obtain a resin having a low molecular weight, it is necessary to use a large amount of an initiator. In this case, the obtained resin has a disadvantage of causing coloring due to an aromatic ring.

[0004]

When an acrylic resin is produced by polymerizing a composition containing an acrylic monomer or the like, an acrylic resin which is less colored and has high transparency by using a polymerization initiator which is easy to handle. It is desired to establish a manufacturing method for obtaining the same.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a specific organic peroxide is used as a polymerization initiator for a composition containing an acrylic monomer or the like. , Found that the viscosity of the resulting acrylic resin is low, and that excellent transparency can be produced,
The present invention has been completed.

That is, (1) a method for producing an acrylic resin, which comprises using an organic peroxide represented by the following formula (1) or a polymerization initiator composition containing the same:

Embedded image (Where R represents an alkyl group having 2 to 5 carbon atoms) (2) The present invention relates to an acrylic resin obtained by the production method described in (1).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail. The organic peroxide of the formula (1) used in the polymerization initiator used in the present invention or the polymerization initiator composition containing the same is produced in the same manner as in a usual method for producing an organic peroxide. . That is, a tertiary alcohol and hydrogen peroxide are added in the presence of an acidic substance for 10 to 10 hours.
It is obtained by performing a dehydration reaction at 80 ° C. for 10 minutes to 4 hours.

The polymerization initiator used in the present invention or the polymerization initiator composition containing the same may be used in addition to the organic peroxides represented by the formula (1) and other organic peroxides usually used in polymerization initiators. May be contained. Specific examples of the organic peroxide of the formula (1) include di-t-amyl peroxide and di-t-amyl peroxide.
t-hexyl peroxide, bis-1,1,3,3
-Tetramethylbutyl peroxide and the like.

Specific examples of the other organic peroxide include:
t-butyl peroxy 2-ethylhexanoate and t-
Peresters such as butyl peroxyacetate, t-
And percarbonates such as butyl peroxyisopropyl carbonate. These are used in an amount of 0 to 100 parts by weight with respect to 100 parts by weight of the polymerization initiator (organic peroxide) of the formula (1). What is necessary is just to add and mix each required amount to a monomer composition separately.

The amount of the polymerization initiator used in the present invention or the polymerization initiator composition containing the same is usually 0.01 to 30 parts by weight, more preferably 2 to 30 parts by weight, per 100 parts by weight of the monomer composition. 20 parts by weight, which is determined according to the physical properties of the target resin.

In the present invention, the starting monomer is n
-One or a mixture of two or more (meth) acrylates such as butyl acrylate, methyl methacrylate, hydroxyethyl methacrylate,
These may be used in combination with a monomer copolymerizable with the above-mentioned monomers such as styrene, acrylic acid, acrylonitrile, and vinyl acetate. The used amount is 0 to 100 parts by weight based on 100 parts by weight of the acrylic monomer, and may be simply added and mixed.

In the method for producing an acrylic resin of the present invention, a solvent may be used. Specific examples of solvents that can be used include hydrocarbon solvents such as xylene, ester solvents such as ethyl acetate, butyl acetate, Exxate700 (manufactured by Exxon), alcohol solvents such as isopropanol, butyl cellosolve, and water. . These solvents may be used as a mixture of two or more kinds. The use amount of these solvents is 0 to 300 parts by weight, more preferably 25 to 100 parts by weight, based on 100 parts by weight of the acrylic monomer or the composition thereof, taking into account the physical properties of the intended acrylic resin. You can decide.

In the method for producing an acrylic resin according to the present invention, the acrylic monomer or a mixture thereof is added to a solvent in a reaction vessel maintained at a temperature selected from, for example, 120 to 180 ° C., preferably 140 to 160 ° C. A polymerization initiator is previously mixed with the composition at 10 to 40 ° C., and the mixture is dropped and polymerized usually over 2 to 40 hours, preferably 3 to 8 hours. In the course of polymerization, the polymerization temperature can be changed.

[0014]

EXAMPLES Next, the present invention will be described in more detail with reference to examples and reference examples, but these are only examples and do not limit the present invention.

Reference Example In a 1-liter four-necked flask equipped with a stirrer, a dropping funnel, a reflux condenser and a thermometer, t-amyl alcohol 176 was added.
g and 52 g of 60% hydrogen peroxide, and 150 g of a 98% aqueous sulfuric acid solution was added dropwise over 1 hour with good stirring.
Warm to ° C and continue stirring for another 3 hours. After the reaction is completed,
Allow to cool, remove the organic layer, and add 10% aqueous sodium hydroxide solution 2
After washing with 200 g of 5% saline solution, 10 g of magnesium sulfate was added to remove water to obtain di-t-amyl peroxide (DTAP) (95% yield). The purity of the obtained di-t-amyl peroxide was 95%.

The purity was calculated from the ratio of the peak area of the target substance to the area of the entire product obtained by gas chromatography analysis.

Example 1 The following polymerization was carried out to obtain an acrylic resin having a number average molecular weight of 2,000 to 3,000, a narrow molecular weight distribution and no coloring.
That is, 40 g of Exxate700 was put into a 200 glass reactor, and the temperature was raised to 150 ° C. 10 g of methyl methacrylate, 20 g of styrene, n-butyl acrylate 4
0 g, hydroxyethyl methacrylate 28 g, and methacrylic acid 2 g to 100 g of a monomer composition, di-t-amyl peroxide was added as a polymerization initiator, and the mixture was mixed quickly.
This temperature was maintained for a period of time to complete the polymerization. The viscosity of the obtained acrylic resin was measured by a B-type viscometer, and the molecular weight (standard sample: polystyrene) was measured by gel permeation chromatography (GPC). The coloring of the resin was visually determined. Table 1 shows the results. In Table 1, molecular weight Mw means weight average molecular weight, and molecular weight Mn means number average molecular weight. The molecular weight distribution (D) was calculated by the following equation: D = Mw / Mn.

Comparative Example 1 Di-t-butyl peroxide (DT) was used as a polymerization initiator.
Polymerization was carried out in the same manner as in Example 1 except that BP) was used and the amount used was changed. Table 1 shows the results.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that dicumyl peroxide (DCP) was used as a polymerization initiator and the amount used was changed. Table 1 shows the results.

[0020]

Table 1 Polymerization initiator Physical properties of obtained acrylic resin Name Used amount Viscosity Molecular weight Molecular weight Color distribution (g) Poise Mw Mn D Example 1 DTAP 5.8 260 4500 2400 1.88 Colorless Comparative Example 1 DTBP 4 .4 440 12300 4400 2.80 colorless 2 DCP 8.3 350 8600 4200 2.05 pale yellow

From these results, it can be seen that the acrylic resin obtained by the method for producing an acrylic resin of the present invention has a low viscosity, a small molecular weight distribution and no coloring.

[0022]

A method for producing an acrylic resin having a low viscosity and a high transparency has been established.

Claims (2)

[Claims] 1. A method for producing an acrylic resin, comprising using an organic peroxide represented by the following formula (1) or a polymerization initiator composition containing the same. Embedded image (Where R represents an alkyl group having 2 to 5 carbon atoms) 2. An acrylic resin obtained by the production method according to claim 1.