JPH0633033A - Production of tackifying resin for acrylic tack agent - Google Patents

Abstract

PURPOSE:To obtain the subject resin capable of giving acrylic tack agents usable in diversified applications by reaction of limonene with maleic anhydride under heating followed by esterification with an alcohol. CONSTITUTION:(A) 100 pts.wt. of limonene (e.g. d-limonene) is made to react with 10-100 (pref. 50-80) pts.wt. of maleic anhydride in the presence or absence of an acid catalyst (e.g. sulfuric acid, p-toluenesulfonic acid) pref. at 125-140 deg.C for 2hr under heating. (B) The product obtained in the process A is esterified with an alcohol (e.g. methyl alcohol, glycol) to obtain the objective tackifying resin for acrylic tack agents. Addition of this resin to an acrylic tack agent gives the objective acrylic improved tackiness compared to those using acrylic copolymer alone; therefore, the resulting tack agent can be used in diversified applications, esp. in adhesive tapes for polyolefins.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is used in addition to an acrylic pressure-sensitive adhesive, for pressure-sensitive adhesive tapes, especially pressure-sensitive adhesive tapes for polyolefins, and pressure-sensitive adhesive labels, particularly polyvinyl chloride-based, polyolefin-based, and styrene-based pressure-sensitive adhesive labels. The present invention relates to a method for producing a tackifying resin for an acrylic pressure-sensitive adhesive.

[0002]

2. Description of the Related Art Recently, pressure-sensitive adhesive products such as pressure-sensitive adhesives are easy to package and economically advantageous, and pressure-sensitive adhesives are required to display contents, and bar codes are required for product management. The use of the system is increasing from the viewpoint of beautifying the packaging. The base materials of these products are also paper-based, polyvinyl chloride-based, from the standpoint of improving the water resistance and weather resistance strength in frozen storage, store display, refrigerator storage at home, etc.
There are a wide variety of products including polyolefins and styrenes. Also, the pressure-sensitive adhesive has changed from a conventional natural rubber-based pressure-sensitive adhesive to an acrylic-based pressure-sensitive adhesive. Acrylic pressure-sensitive adhesives use ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate or the like as the monomer, and various combinations have been used for various purposes. Since such an acrylic copolymer has a sharp molecular weight distribution and is in a limited range, a wide variety of blending is required.

On the other hand, from the point of view of use, indoors, outdoors, environments such as cold and warm, types of adherends, contamination, shape, difference in sticking system, or hand-sticking are very versatile and required performances. Are also varied. Further, the plastic system has a remarkably large surface tension as compared with the paper system, and it is complicated because the pressure-sensitive adhesive coating needs treatment such as undercoating and corona discharge. In addition, some plastics have little or no polar groups,
Its interfacial tension is large, and wetting is poor at the time of coating. Further, the pressure-sensitive adhesive has a high molecular weight, and the molecular weight distribution is often sharp and sharp, but it is generally said that the molecular weight distribution should not be sharp.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides an acrylic pressure-sensitive adhesive that can be used for various purposes, in which the molecular weight distribution of the acrylic pressure-sensitive adhesive is not sharp and has a wide width, and the adhesiveness is also improved. It is an object of the present invention to develop a method for producing a tackifying resin for an acrylic pressure-sensitive adhesive which is made possible.

[0005]

In order to solve the above problems, the present invention is obtained by esterifying a product obtained by heating and reacting limonene and maleic anhydride in the presence or absence of an acidic catalyst. By blending an esterified product with a conventional acrylic pressure-sensitive adhesive, it is possible to broaden the molecular weight distribution and also improve the tackiness. This esterified product is produced by esterifying 100 parts of limonene with 10 to 100 parts of maleic anhydride, preferably 50 to 80 parts by heating with an acidic catalyst or in the absence of an acidic catalyst, and esterifying a product obtained with an alcohol. It was done. The heating reaction is preferably at 125 to 140 ° C. for about 2 hours. The esterification may be saturated esterification or semi-saturated esterification.

Limonene is contained in the skin of citrus fruits, and is obtained by isomerizing turpentine oil obtained from pine trees and turpentine oil obtained from pulp cooking. In the present invention, d-, l- , Dl-type can be used. Examples of acidic catalysts include inorganic acids such as sulfuric acid, hydrochloric acid and phosphoric acid; alkylbenzene sulfonic acids such as p-toluenesulfonic acid; aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid and butyric acid; benzoic acid and p-tert-butylbenzoic acid. Aromatic carboxylic acids such as trimellitic anhydride; Dibasic acids such as oxalic acid, maleic acid and malonic acid can be used. As alcohols, methyl alcohol,
A monohydric alcohol such as ethyl alcohol; a polyhydric alcohol such as glycol can be used.

[0007]

By using the tackifying resin for an acrylic pressure-sensitive adhesive of the present invention, the molecular weight distribution becomes broader and good adhesive property values can be obtained as compared with those using only the acrylic copolymer.

[0008]

[Examples and Comparative Examples]

Example 1 100 parts of d-limonene, 75 parts of maleic anhydride and 0.35 part of p-toluenesulfonic acid (0.2% of the charged amount) were reacted at 125 to 140 ° C. for 2 hours in a nitrogen gas stream. After that, unreacted materials were removed under reduced pressure at 120 ° C. or lower to obtain 216 parts of viscous transparent liquid (total acid value 440, saponification value 460). 100 parts of this reaction product was subjected to an esterification reaction with 49 parts of methanol to obtain a transparent liquid product having a total acid value of 15 and a saponification value of 16.

Example 2 100 parts of the maleated limonene reaction product of Example 1 was subjected to an esterification reaction with 71 parts of bentaerythritol,
A transparent liquid having a total acid value of 14 and a saponification value of 15 was obtained.

Example 3 100 parts of the maleated limonene product of Example 1 was subjected to an esterification reaction with 47 parts of ethylene glycol to obtain a viscous transparent liquid having a total acid value of 16 and a saponification value of 15.

Next, 20 parts of the tackifying resin for an acrylic pressure sensitive adhesive of the esterified product obtained in Examples 1 to 3 was added to the acrylic pressure sensitive adhesive to evaluate the tackiness. In addition, the tackiness of the acrylic pressure-sensitive adhesive to which nothing was added was also evaluated (Comparative Example 1). The results are shown in Table 1. The pressure-sensitive adhesive was evaluated by the following method. A. Evaluation of Adhesiveness (1) Preparation of Adhesive Film A polyethylene film having a thickness of 70 μm was coated with an adhesive agent at a dry time of 20 μm.
After being coated so as to have a thickness of μm, the SUS27 stainless steel is pressure-bonded with a load of 1 kg three times by a rubber roll to be stuck, and then left in a thermostatic chamber at room temperature of 20 ° C. and a temperature of 60% for 24 hours. (2) Test method-Ball tack Ball tack DOW method-Adhesive force according to JIS-Z-1522-Holding force According to JIS-Z-1524-Anchoring force Visually

[0013]

[Table 1]

[0014]

[Table 1]

[0015]

EFFECT OF THE INVENTION By using the acrylic pressure-sensitive adhesive tackifying resin obtained by the production method of the present invention in the acrylic pressure-sensitive adhesive, the molecular weight distribution width can be made wider, and the adhesiveness is improved. It can be used for various purposes.

Claims (1)

[Claims] 1. Limonene 100 parts and maleic anhydride 10
To 100 parts by heat reaction in the presence or absence of an acidic catalyst, and further esterified with alcohols to produce a tackifying resin for acrylic pressure-sensitive adhesives.