JPS58162611A - Production of acrylic polymer emulsion - Google Patents

Abstract

PURPOSE:The emulsion polymerization of acrylic monomers is carried out in the presence of a specific amount of a completely saponified polyvinyl alcohol in which compounds containing sulfonic groups bond to the polyvinyl groups, to produce the titled emulsion with high stability and heat-resistant adhesion. CONSTITUTION:The emulsion polymerization of acrylic monomers such as ethyl acrylate or styrene (100pts.wt.) is carried out in the presence of a completely saponified polyvinyl alcohol (usually 96-99% saponification degree) in which compounds bearing sulfonic or sulfate groups bonding to the polyvinyl groups, preferably in an amount of 3-15pts.wt. at 30-90 deg.C for 1-10hr, when necessary, along with a plasticizer and an antiseptic agent to give the objective emulsion. USE:An adhesion for paper-aluminum foil laminatings.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for emulsion polymerization of acrylic monomers in the presence of modified polyvinyl alcohol.

Furthermore, the acrylic polymer emulsion obtained by this production method is mainly useful as an adhesive for paper-aluminum foil laminates, which requires heat-resistant adhesive properties.

When an acrylic polymer emulsion using a conventional emulsifier is used as an adhesive for paper-aluminum foil laminates, wrinkles appear on the surface of the aluminum foil adhered to the paper, resulting in poor heat-resistant adhesive properties. In addition, the acrylic polymer emulsion obtained by emulsion polymerization of acrylic monomers in the presence of water-soluble polymer compounds, such as polyvinyl alcohol, is unstable and cannot be used as an adhesive for paper-aluminum foil laminates. Even if it is possible, the surface of the aluminum foil bonded to the paper will wrinkle and the heat-resistant adhesive properties will be poor. As a result of intensive studies to solve the above problems, the present inventors found that in the presence of completely saponified polyvinyl alcohol containing a compound having a sulfonic acid group or a sulfuric acid group bonded to the polyvinyl group in the polyvinyl alcohol. It was discovered that an acrylic polymer emulsion obtained by emulsion polymerization of acrylic monomers has excellent stability and excellent heat-resistant adhesive properties as an adhesive for paper-aluminum foil laminates, and the present invention was made based on this discovery. It has been completed.

In other words, completely saponified polyvinyl alcohol containing a compound having a sulfonic acid group or a sulfuric acid group bonded to a polyvinyl 2-group in polyvinyl alcohol (
(hereinafter abbreviated as denatured polyvinyl alcohol) 1 to 20ii
1. A method for producing an acrylic polymer emulsion, which comprises emulsifying and polymerizing 100 parts by weight of an acrylic spinning wheel in the presence of 100 parts by weight. The present invention will be explained in detail below.

Modified polyvinyl alcohol has the infrared absorption spectrum shown in Figure 1, and is completely saponified type (usually saponified type 96-99
The amount used is 1 to 2011 parts, preferably 3 to 15 parts, per 100 parts by weight of the acrylic *m body, preferably 3 to 15 parts, and 1 part by weight.
Acrylic polymer emulsions are less safe under gas. For example, agglomerates and separation may occur during polymerization, solidification may occur, and heat-resistant adhesive properties may be poor. At temperatures above 20°C, the viscosity increases significantly at low temperatures. The modified polyvinyl alcohol may be present at any time from before the start of emulsion polymerization of the acrylic monomer to the end of the emulsion polymerization, but it must be present before the start of emulsion polymerization of the acrylic monomer9. is preferred. Acrylic monomers include acrylic esters,
For example, ethyl acrylate, butyl acrylate, 112-ethylhexyl acrylate, methyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, acrylamides, and the like. In addition, styrene, acrylic nitrile, vinyl acetate, acrylic acid, methacrylic acid, unsaturated higher fatty acid vinyl esters, etc. are emulsion polymerized in appropriate combinations, preferably acrylic esters and styrene are the main components. These ingredients are copolymerized with glycidyl methacrylate, acrylic acid, methacrylic acid, etc. Catalysts used in emulsion polymerization are usually persulfates such as potassium persulfate and ammonium persulfate. Emulsifiers are, in principle, unnecessary, but can be used within the range of surfactant types and amounts that do not adversely affect the adhesion of the paper-aluminum foil heat-resistant adhesive base. Polymerization conditions are polymerization part-4
- The polymerization time is usually 30 to 90°C for 1 to 10 hours during polymerization.

Use additives such as plasticizers and preservatives as necessary9
It's okay. The paper that is bonded to the aluminum foil can be tissue paper, paperboard, or high-quality paper. The acrylic polymer emulsion obtained by the production method of the present invention is used as an adhesive for paper-aluminum foil laminates, particularly for food packaging where heat-resistant adhesiveness is required. Examples and comparative examples of the present invention are shown below. In addition, parts and % are weight I! It is standard.

Example-1 43 parts of water, 14 parts of Gohsenol CKS-50 (manufactured by Nippon Gosei Kagaku Co., Ltd., anionic fully saponified type (saponification degree 98 mol%) modified polyvinyl alcohol having the characteristic absorption shown by the infrared absorption spectrum in Figure 1) was charged into the polymerization zone and dissolved at room temperature. Then, a mixed solution of 25 parts of styrene, 4 parts of acrylic H2-ethylhexyl, 2 parts of acrylic acid, 4 parts of glycidyl methacrylate, and 8 parts of acetyltributyl citrate was added to the mixture with 5 parts of ammonium persulfate solution. Polymerization was carried out by sequential addition over 4 hours at 80-5-℃, and after cooling to room temperature, 4 parts of acetyltributyl citrate and 1 part of aqueous ammonia were added to obtain a stable emulsion with a solid content of 50%, a viscosity of 20,000 PS, and a pH of 8.0. The above emulsion was diluted with water so that the solid content was 30%, and this diluted water solution was applied to thin paper using a bar coater No. 5, and then a 7 micron thick aluminum foil was layered and laminated using a hot air dryer. 1 at 120℃
Dry with heat for 5 seconds, leave at 24vIII, then heat to 230°C.
As a result of observing the heat-resistant adhesion after ironing for 1 minute,
A good paper-aluminum part with no wrinkles on the paper surface was obtained.

Comparative Example-1 In Example-1, 2 parts of a nonionic surfactant (Nonion NS-210 manufactured by NOF Corporation) and an anionic surfactant (R&
Company H - Example using 2 parts of Tridon X-200)
An acrylic polymer emulsion was produced in the same manner as in 1-6- to obtain a stable emulsion with a solid content of 50%, a viscosity of 200 CPS, and a pH of 8.0. When this was laminated with paper and aluminum foil in the same manner as in Example 1, significant wrinkles occurred on the paper surface and good paper-aluminum suspension could not be obtained.

[Brief explanation of the drawing]

FIG. 1 shows the infrared absorption spectrum of a modified vinyl alcohol, specifically Gohsenol CKS-50 (anionic completely saponified type (saponification degree 98 mol%) manufactured by Nippon Gosei Kagaku Co., Ltd.). -7-

Claims (1)

[Claims] Milk+J polymerization of 100 parts by weight of an acrylic monomer in the presence of 1 to 20 parts of fully saponified polyvinyl alcohol in which a compound having a sulfonic acid group or a sulfuric acid group is bonded to a polyvinyl group in polyvinyl alcohol. A method for producing an acrylic polymer emulsion with the following characteristics.