JPH06100751A - Vinyl acetate-ethylene copolymer emulsion containing solid matter in high ratio and its production - Google Patents

Abstract

PURPOSE:To provide the subject vinyl acetate-ethylene copolymer-based emulsion for an emulsion adhesive, containing a remarkably small amount of a surfactant inhibiting the water-resistant bond strength or not containing it and excellent in stability and initial adhesive strength. CONSTITUTION:There are provided a vinyl acetate-ethylene copolymer emulsion containing a vinyl acetate-ethylene copolymer composed of 95 to 60wt.% vinyl acetate and 5 to 40wt.% ethylene and a sulfonic acid group-containing modified polyvinyl alcohol-based resin in an amount of 0.5 to 10 pts.wt. based on 100 pts.wt. vinyl acetate unit contained in the vinyl acetate-ethylene copolymer, exhibiting 65 to 75wt.% solid matter content, <=10000cPs viscosity and 0.6 to 1.2mum average particle diameter, and a method for producing the above emulsion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vinyl acetate-ethylene copolymer emulsion having a low viscosity even at a high solid content and having a high initial adhesiveness and adhesive strength, especially high water resistance, and a method for producing the same. It is about.

[0002]

2. Description of the Related Art The performance required for adhesives is diverse and diverse, but in recent years, in the field of adhesion and adhesion using synthetic resin emulsions, high-speed adhesive machines have been introduced to improve productivity and Adhesive force develops quickly,
So-called adhesives with excellent initial adhesion are desired, and in order to save the drying energy during coating, the solid content of emulsion is as high as possible, the viscosity is low, and it is stable. It is required that the performance such as adhesive strength to be extremely high.

As a material which meets such a demand, a high solid content vinyl acetate-ethylene copolymer emulsion is known.

For example, JP-A-63-223053 discloses a stable vinyl acetate-ethylene copolymer having a solid content of about 65 to 70% by weight, which is polymerized in the presence of a low molecular weight polyvinyl alcohol and a surfactant. Emulsions are described. Further, JP-A-2-274707 describes a vinyl acetate / ethylene / acrylic acid copolymer emulsion having a solid content of 60 to 70% by weight, which is polymerized in the presence of a low molecular weight polyvinyl alcohol and a surfactant. ing. Further, JP-A-2-289640 describes a vinyl acetate / ethylene copolymer emulsion containing a low molecular weight partially saponified polyvinyl alcohol and a surfactant and having a solid content of 65 to 70% by weight.

However, in these proposed vinyl acetate-ethylene copolymer emulsions and vinyl acetate-ethylene-acrylic acid copolymer emulsions, a surfactant is usually used as an emulsifying dispersant based on 100 parts by weight of vinyl acetate units. 2 to 5 parts by weight, at least 1 part by weight or more are blended, and as a result, when these emulsions are used as an adhesive, a significant decrease in water resistance is unavoidable due to the influence of the surfactant.

Further, when the solid content is increased to a high solid content such as 65 to 75% by weight by the conventional method for producing a vinyl acetate-ethylene copolymer emulsion, the viscosity becomes a high viscosity of 10,000 cps or more, and the heat is removed during the polymerization. Difficult and difficult to manufacture.

An emulsion having a high solid content and a low viscosity can be obtained by increasing the particle size. That is, in order to reduce the viscosity, the average particle size is preferably 0.6 to 1.2 μm. When polyvinyl alcohol is used as a protective colloid, the emulsion stability tends to be poor due to the large particle size. In order to improve the storage stability, it is usual to use a surfactant together with polyvinyl alcohol as a protective colloid in an amount of 1 part by weight or more per 100 parts by weight of vinyl acetate unit.

Further, in order to lower the viscosity, various measures have been taken such as lowering the molecular weight of polyvinyl alcohol, but the amount of the surfactant added is still 1 part by weight or less based on 100 parts by weight of vinyl acetate unit. I couldn't.

[0009]

SUMMARY OF THE INVENTION In the present invention, when an emulsion is coated and dried on an adherend and used as an adhesive, the surfactant used for stabilizing the emulsion has a water-resistant adhesive strength. Paying attention to the inhibition, it is a vinyl acetate-ethylene copolymer emulsion with good stability and high solid content, and whether these surfactants are not used at all,
Alternatively, even if used, it is possible to secure stability with the use of an extremely small amount, vinyl acetate-ethylene which is excellent in so-called initial adhesiveness, which improves water-resistant adhesiveness to an adherend and exhibits rapid adhesiveness after coating. The purpose is to obtain a copolymer emulsion.

[0010]

The present invention is directed to vinyl acetate-
The ethylene copolymer emulsion contains 0.5 to 10 parts by weight of a sulfonic acid group-containing modified polyvinyl alcohol resin per 100 parts by weight of vinyl acetate units in the copolymer, and has a solid content of 65 to 75% by weight and a viscosity of 10,000
vinyl acetate-ethylene, characterized in that the copolymer has a composition of 95-60% by weight of vinyl acetate and 5-40% by weight of ethylene. A copolymer emulsion and vinyl acetate, 0.5 to 10 parts by weight of a modified polyvinyl alcohol resin containing a sulfonic acid group and an appropriate amount of water are mixed per 100 parts by weight of the vinyl acetate to prepare a monomer emulsion, and an ethylene partial pressure of 5 to 5 is obtained. 150 kg / cm ² , reaction temperature 10 to 1
At 50 ° C., emulsion polymerization is carried out using a radical polymerization initiator or a redox catalyst to obtain a solid content of 65-65.
75% by weight, viscosity 10,000 cps or less, vinyl acetate content 95 as an average particle size of 0.6 to 1.2 μm
The above object was achieved by developing a method for producing a vinyl acetate-ethylene copolymer emulsion having -60% by weight and an ethylene content of 5-40% by weight.

The raw materials for the vinyl acetate-ethylene copolymer of the present invention include vinyl acetate and ethylene as main monomers. Other than this, vinyl esters other than vinyl acetate as the third comonomer, for example, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl caproate, vinyl heptanoate, vinyl caprylate, vinyl pelargonate, vinyl versatate, n- Acrylic esters such as vinyl undecanoate and vinyl laurate, such as methyl acrylate, ethyl acrylate, and acrylic acid-2-
Ethylhexyl, etc., acrylamide, acrylamide derivatives such as alkoxymethyl acrylamide and N-
Methylol acrylamide and the like and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate,
Copolymerizable monomers such as butyl methacrylate and 2-ethylhexyl methacrylate may be copolymerized.
These third comonomers are preferably 10 parts by weight or less with respect to 100 parts by weight of vinyl acetate.

The protective colloid of the present invention is a sulfonic acid group-containing modified polyvinyl alcohol resin. This product is useful as a protective colloid for emulsions, and is a commercially available product (Nippon Gosei Kagaku Kogyo Co., Ltd., trade name: Gocelan L-3266, anion type, saponification degree 86-
90% polyvinyl alcohol modified product).

The sulfonic acid group-containing modified polyvinyl alcohol resin is used in an amount of 0.5 to 10 parts by weight, preferably 1 to 6 parts by weight, per 100 parts by weight of the vinyl acetate unit used. When this amount is less than 0.5 parts by weight, coarse particles are generated, which hinders the stability as an emulsion and easily causes a precipitate. On the other hand, an emulsion used in an amount of more than 10 parts by weight has a poor water resistance of the film made from the emulsion, and a part thereof is dissolved in water, so that the emulsion does not meet the purpose of the present invention.

The use of this protective colloid is such that the average particle size of the emulsion copolymerized within the above range is from 0.6 to
The particle size is 1.2 μm, the particle size is relatively large, and the viscosity is 10,000 cps or less.

Further, in the present invention, ordinary polyvinyl alcohol may be used in combination as a dispersant. In this case, partially saponified polyvinyl alcohol, which has less temperature dependence of emulsion viscosity, is preferable. The amount of polyvinyl alcohol used is preferably 3 parts by weight or less per 100 parts by weight of vinyl acetate. If it is used in an amount of more than 3 parts by weight, the viscosity of the emulsion exceeds 10,000 cps, which makes production difficult.

When a sulfonic acid group-containing modified polyvinyl alcohol resin is used as a protective colloid, a stable and high solid content emulsion is usually obtained by a single formulation (without the use of a surfactant). For example, it is possible to use a polyoxyethylene-based nonionic surfactant together for the purpose of enhancing the emulsifying action and improving the affinity with the adherend. In this case, addition should be limited to less than 1 part by weight, preferably 0.8 part by weight or less, based on 100 parts by weight of vinyl acetate. Addition of more than 1 part by weight becomes an inhibitor to the adherend when used as an adhesive, and is likely to cause a decrease in adhesive force, particularly a cause of a decrease in water-resistant adhesive force. Addition within this range has no adverse effect on the average particle size of the emulsion and the viscosity is 10,000
A stable emulsion having a low viscosity of 0 cps or less can be obtained.

In this case, specific examples of the polyoxyethylene nonionic surfactant that can be used include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester. Etc.

The radical polymerization initiator used in the present invention includes
Persulfate compounds such as ammonium persulfate, potassium persulfate and sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide,
There are peroxides such as benzoyl peroxide and ammonium peroxoborate, potassium peroxoborate, and peroxoborate salts such as sodium peroxoborate. In some cases, a so-called redox catalyst in which a reducing agent is used in combination is available. Although included, a water-soluble radical polymerization initiator is convenient in operation. The amount used is 0.01 to 10% by weight, and particularly preferably 0.05 to 5% by weight, based on the total weight of the reaction system.

In the industrial production of the vinyl acetate-ethylene copolymer emulsion of the present invention, any method of batch type, anti-continuous type or continuous type using a high pressure reactor can be employed, and heat removal with profitability is possible. To be quantitative, the emulsion viscosity must be 10,000 cps or less. The ethylene content of the vinyl acetate-ethylene copolymer depends on the ethylene pressure during the polymerization process, and the higher the ethylene pressure, the higher the ethylene content. Ethylene content mainly affects film properties such as strength and elongation of films made from the emulsion,
It also affects the adhesion to the adherend. Therefore, in order to meet a wide variety of demands, it has to be produced under various ethylene pressures, and therefore the range is usually 5 to 5.
It is considered to be 150 kg / cm ² , but 10 to 100 kg
/ Cm ² is the most common.

The reaction temperature is 10 to 150 ° C., especially 30 to 1
00 ° C is preferred.

The emulsion polymerization is carried out by mixing a predetermined amount of vinyl acetate, a modified sulfonic acid group-containing modified polyvinyl alcohol resin, and optionally a polyoxyethylene nonionic surfactant, and water to prepare a vinyl acetate emulsion, which is then added. It is performed by pressurizing ethylene.

The vinyl acetate-ethylene copolymer emulsion produced as described above contains 0.5 to 10 parts by weight of a modified polyvinyl alcohol resin containing a sulfonic acid group per 100 parts by weight of vinyl acetate unit, and a solid content of 65 to 65. 75% by weight, viscosity 10,000 cps or less, average particle size 0.6
It can be made into a copolymer emulsion consisting of 95 to 60% by weight of vinyl acetate and 5 to 40% by weight of ethylene. When a polyoxyethylene nonionic surfactant is used in combination, the amount of this surfactant is less than 1 part by weight per 100 parts by weight of vinyl acetate unit.

This emulsion has a low viscosity even at a high solid content concentration, so that it is easy to remove heat and is not difficult to produce. Moreover, since the average particle size is appropriate, it is possible to maintain a low viscosity and to stabilize it. It has excellent properties. The greatest feature is that no surfactant is used, or even if it is used, it is about 1
Since a very small amount such as / 3 or less is required, the feature that the adhesive strength, especially the water resistance strength can be maintained high is brought about.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. The method for evaluating the physical properties of the emulsion is as follows.

(1) Physical properties of emulsion Solid content: 110 ° C., evaporation residue after drying for 3 hours (wt%) Viscosity: BL type viscometer, 10 rpm, 30 ° C. Average particle size: 0.01 wt% solid content in water The emulsion diluted and diluted was determined by a dynamic light scattering measurement method using a laser as a light source.

(2) Adhesive performance Initial adhesiveness: B liner paper (basis weight 300 g / m ² ).
Apply 30g / m ^{2 on} the surface of the product with an adhesive applicator, immediately stick it to the back of the B-liner paper, press it 3 times with a rubber roll, and find the number of seconds required for 50% paper break, and use this for the initial adhesion. It was speed. PVC / plywood adhesive strength: 12g emulsion on plywood
/ 900 cm ² applied, laminated vinyl chloride sheet, pressed at 2 Kg / cm ² for 24 hours, then 20 ° C, 65R
It was cured at H% for 2 days.

As for the normal strength, the laminated plate was cut into 1-inch widths, and the 180-degree peel strength was measured under the conditions of 20 ° C., 65 RH%, and a pulling speed of 10 mm / min. Further, the water resistance strength was the same as that of the normal strength. The sample was immersed in water at 20 ° C. for 24 hours, and the peel strength of the sample immediately after being taken out was measured under the same conditions.

Example 1 The following components were charged in a stainless steel dissolution pot equipped with an anchor type stirrer having an internal volume of 60 L, and the components were stirred and dissolved at 50 ° C. for 2 hours to obtain a uniform aqueous solution. Water 7361.0 g Gocelan L-3266 * 750.0 g * Sulfonic acid group-containing modified polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Next, in the aqueous solution, 14.3 g of sodium phosphate dibasic and metabisulfite are added. 200 g of soda was added and dissolved, and cooled to 30 ° C or lower. Further, 15593.8 g of vinyl acetate was gradually added to the above aqueous solution with stirring to obtain an emulsion of vinyl acetate monomer.

25% of this monomer emulsion was added to an internal volume of 3
It was charged in a stainless steel autoclave equipped with a 0 L anchor type stirrer, then the air in the autoclave was sufficiently replaced with nitrogen and ethylene, and the monomer emulsion was heated to 72 ° C. under stirring and the ethylene pressure was 50 kg / cm 2. ²
After increasing the temperature to 72 ° C, ethylene pressure to 50 kg /
Polymerization was carried out for 1 hour while controlling to cm ² . After maintaining this condition for 1 hour, the remaining 75% of the monomer emulsion was uniformly added for 7 hours to carry out polymerization. At this time, as a polymerization catalyst, 1081 g of a 5.8% aqueous solution of ammonium persulfate was uniformly added dropwise for 10 hours from the beginning of the polymerization. The aging temperature was raised to 80 ° C. from the 9th hour and aging was carried out for 1 hour.

(Example 2) A homogeneous aqueous solution of the following components was obtained in the same dissolving vessel as in Example 1 by the same method. Water 7361.0 g Gocelan L-3266 250.0 g Gohsenol GL-03 * 375.0 g * Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd.)
Then, as in Example 1, sodium diphosphate, sodium metabisulfite and vinyl acetate were added to obtain a vinyl acetate monomer emulsion, and then polymerization was carried out in the same manner as in Example 1. .

(Example 3) A uniform aqueous solution of the following components was obtained in the same dissolving vessel as in Example 1 by the same method. Water 7361.0 g Gocelan L-3266 375.0 g Gohsenol GL-03 375.0 g Emulgen 950 * 62.5 g * Polyoxyethylene-based nonionic surfactant (manufactured by Kao Soap Co., Ltd.) Similarly, after dibasic sodium phosphate, sodium metabisulfite and vinyl acetate were added to obtain a vinyl acetate monomer emulsion, polymerization was carried out in the same manner as in Example 1.

(Example 4) A modified polyvinyl alcohol resin containing sulfonic acid group (Goselan L-3266) was used.
Polymerization was carried out in the same manner as in Example 1 except that the amount was increased to 000 g.

(Embodiment 5) Ethylene pressure is 60 kg / cm.
Polymerization was performed in the same manner as in Example 1 except that the number was ² .

(Comparative Example 1) A homogeneous aqueous solution of the following components was obtained in the same dissolving vessel as in Example 1 by the same method. Water 7361.0 g Gocelan L-3266 1871.0 g Polymerization was carried out in the same manner as in Example 1 except that the aqueous solution was used.

(Comparative Example 2) A homogeneous aqueous solution of the following components was obtained in the same dissolving vessel as in Example 1 by the same method. Water 7361.0 g Gohsenol GM-14 * 625.0 g * Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd.)
Production) Emulgen 950 375.0 g Polymerization was carried out in the same manner as in Example 1 except that the aqueous solution was used.

(Comparative Example 3) A homogeneous aqueous solution of the following components was obtained in the same manner as in Example 1 by the same method. Water 7361.0 g Gocelan L-3266 750.0 g Emulgen 950 375.0 g Polymerization was carried out in the same manner as in Example 1 except that the aqueous solution was used.

(Comparative Example 4) A uniform aqueous solution of the following components was obtained in the same dissolving vessel as in Example 1 by the same method. Water 7361.0 g Gocelan L-3266 250.0 g Gohsenol GL-03 375.0 g Emulgen 950 375.0 g Polymerization was carried out in the same manner as in Example 1 except that the aqueous solution was used. Table 1 shows the physical properties and adhesion performance results of the vinyl acetate-ethylene copolymer emulsions produced in the above Examples and Comparative Examples.

[0038]

[Table 1]

[0039]

The vinyl acetate-ethylene copolymer emulsion obtained by the present invention is stable without the use of a surfactant, has a low viscosity even at a high solid content, and has an initial adhesive property. The film obtained from the emulsion is excellent in water resistance, is tough, and has the characteristics of being highly flexible, and is suitable for various adhesives.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C09J 131/04 PEY 6904-4J // (C08L 31/04 23:08)

Claims (4)

[Claims] 1. A vinyl acetate-ethylene copolymer emulsion comprising 0.5 to 10 parts by weight of a modified polyvinyl alcohol resin containing a sulfonic acid group per 100 parts by weight of vinyl acetate units in the copolymer, and having a solid content of 65-75
% By weight, viscosity is 10,000 cps or less, average particle size is 0.6 to 1.2 μm, and the composition of the copolymer is 95 to 60% by weight of vinyl acetate and 5 to 40% by weight of ethylene. A characteristic vinyl acetate-ethylene copolymer emulsion. 2. The vinyl acetate according to claim 1, which contains, as an emulsifying dispersant, a polyoxyethylene-based nonionic surfactant not exceeding 1 part by weight per 100 parts by weight of the vinyl acetate unit in the vinyl acetate-ethylene copolymer. -Ethylene copolymer emulsion. 3. Vinyl acetate, 0.5 to 10 parts by weight of a modified polyvinyl alcohol resin containing a sulfonic acid group and an appropriate amount of water are mixed per 100 parts by weight of the vinyl acetate to prepare a monomer emulsion, and an ethylene partial pressure of 5 to 5 is obtained. 150 kg / cm
^2. Emulsion polymerization is carried out at a reaction temperature of 10 to 150 ° C. using a radical polymerization initiator or a redox catalyst to obtain a solid content of 65 to 75% by weight and a viscosity of 10,000 c.
ps or less, vinyl acetate content 95 to 60% by weight, ethylene content 5 as a composition having an average particle size of 0.6 to 1.2 μm
A method for producing a vinyl acetate-ethylene copolymer emulsion, which is -40% by weight. 4. The vinyl acetate according to claim 3, which contains, as an emulsifying dispersant, a polyoxyethylene-based nonionic surfactant not exceeding 1 part by weight per 100 parts by weight of the vinyl acetate unit in the vinyl acetate-ethylene copolymer. A method for producing an ethylene copolymer emulsion.