JPH0335328B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ethylene-vinyl acetate copolymer resin molding material having good fluidity or a hot melt composition molding material containing an ethylene-vinyl acetate copolymer resin as a component thereof. Molding materials such as ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) pellets can cause strong blocking between pellets during the pellet manufacturing process, subsequent storage, transportation, etc. In addition, due to its extremely poor fluidity, the production and packaging of pellets required a great deal of labor, making it difficult to store and transport them for long periods of time. Furthermore, when pellets are used, their poor fluidity causes significant problems during the unpacking, charging, dissolving, and mixing processes. Various treatment methods for pellets have been proposed to alleviate these adverse effects. For example, there is a method in which the surface of pellets is coated with an inorganic substance such as talc or silica, powdered polyethylene, polyethylene wax and its dispersion, EVA dispersion, etc. However, there are many problems with the various methods described above. For example, when inorganic substances such as talc and silica are mixed and added to EVA, a large amount must be added in order to provide practical fluidity and anti-adhesive effects to coated pellets. However, because it has extremely poor compatibility with EVA, there is a problem in that it significantly impairs the performance of end products. In addition, when powdered polyethylene is mixed and adhered to EVA pellets, when the pellets to be coated are dissolved in a solvent and used, the solution becomes cloudy, and if a large amount is added,
It has drawbacks such as having an adverse effect on the adhesive properties of EVA. For example, in the method of coating polymer pellets with an aqueous slurry of fine polyolefin powder described in U.S. Pat. In addition, it has the same drawbacks in terms of use as the powdered polyethylene coating described above. Furthermore, when EVA pellets are coated with polyethylene wax or a dispersion mainly composed of polyethylene wax, as proposed in JP-A No. 56-67209, etc., there is a certain degree of effect on the adhesive resistance. However, it is not possible to obtain practical fluidity, and even if the amount of polyethylene wax coated is small, there is a problem that it becomes emulsified when the EVA pellets to be coated are dissolved. However, the use of a large amount of the coating agent in order to obtain coated pellets with good fluidity is subject to significant restrictions from the viewpoint of its use. In addition, the high-viscosity ethylene polymer pellets proposed in JP-A No. 48-32939, etc. have low adhesive properties.
When coating with an EVA dispersion, the EVA used as a coating agent has a low melting point and, depending on the vinyl acetate content in the material, can actually prevent stickiness and have good fluidity. There are problems such as not being able to obtain coated pellets having a . The present inventors have completed the present invention as a result of intensive research into a coating method that overcomes the problems of the above-mentioned prior art, has good fluidity, and has sufficient anti-stick effects. . The present invention provides carboxylic acid in a copolymer obtained by copolymerizing maleic anhydride and acrylic acid in the presence of EVA on the surface of an EVA molding material or a hot melt composition molding material containing EVA as a component. A molding material coated with a coating material consisting of carboxylated EVA and EVA or wax that has neutralized at least 50 chemical equivalents of
The surface of an EVA molding material or a hot melt composition molding material containing EVA as a component,
An aqueous emulsion of EVA or wax using carboxylated EVA, which is obtained by copolymerizing maleic anhydride and acrylic acid in the presence of EVA and neutralizing 50 chemical equivalents or more of the carboxylic acid in the copolymer, is used as an emulsifier. It relates to a method for producing a resin molding material, characterized in that it is coated with a resin molding material. The present invention will be explained in more detail. In the present invention, the carboxylated EVA used to coat the molding material is a copolymer obtained by copolymerizing 1 to 50 parts by weight of maleic anhydride and acrylic acid in the presence of 99 to 50 parts by weight of EVA. 50 or more chemical equivalents of the carboxylic acid, preferably 80 to 100 chemical equivalents, are neutralized. The EVA used here has a vinyl acetate content of 3 to 70% by weight and a melt index of 0.1 to 70% by weight.
500g/10min, preferably vinyl acetate content
It is 10-40% by weight. Furthermore, carboxylated EVA has an acid value of 10 to 300 mgKOH/g, preferably 30 to 100 mg
It is a copolymer of KOH/g, with more than 50 chemical equivalents of the carboxylic acid neutralized. Examples of the wax include paraffin wax, microcrystalline wax, polyethylene wax, and atactic polypropylene. Further, in the present invention, the coated
EVA has a vinyl acetate content of 3 to 90% by weight,
Particular preference is given to EVA, preferably from 15 to 60% by weight. Furthermore, as a hot melt composition containing EVA as a component, a tackifier, a tackifier,
It contains compounding agents such as wax, filler, pigments, etc. as required, and is mainly used as adhesives and coating agents. As the molding material, pellets, chips, blocks, strips, biscuits, drops, loops, etc. are used. In the present invention, the method for coating the molding material is characterized by using an aqueous emulsion of EVA or wax in which 50 chemical equivalents or more of carboxylic acid is neutralized and carboxylated EVA is used as an emulsifier. The emulsion used in the present invention consists of 100 to 1000 parts by weight of EVA or wax and 100 to 10000 parts by weight of water to 100 parts by weight of carboxylated EVA. As the base used to neutralize the carboxylic acid of carboxylated EVA, alkali metals, alkali metal salts, alkali metal hydroxides, alkali metal alkoxides, alkali metal hydrides, ammonia, ammonium salts, organic amines, etc. are used. . The solid content concentration in the emulsion used in the present invention is 1 to 40% by weight, and the average particle size of the emulsion is 3 to 70μ, preferably 5 to 30μ. Furthermore, the average viscosity of the emulsion is 1 to
It is 1000 cp. Carboxylated EVA whose characteristics are described above
For the preparation method of aqueous emulsion, JP-A-52
For example, the method disclosed in Japanese Patent No.-142686 can be used. A method for coating the surface of an EVA molding material or a hot melt composition molding material containing EVA as a component with a carboxylated EVA aqueous emulsion is as follows: 1. During the production of a strand of EVA or a hot melt composition containing EVA as a component,
A method of contacting the aqueous emulsion or a diluted solution of the aqueous emulsion and cutting the strand coated with the emulsion into various shapes. 2. A method for underwater cutting, in which EVA or a hot melt composition containing EVA as a component thereof is cut into the emulsion or into a diluted solution of the aqueous emulsion while being continuously discharged from a press die. 3 The EVA as an EVA molding material or its component
An example of a method is to coat a hot melt composition molding material containing the aqueous emulsion or a diluted solution of the aqueous emulsion uniformly by immersing or spraying the molding material, and then drying the molding material. Even if any of the methods exemplified above are adopted for the emulsion coating, existing processes will not be affected in any way. In addition, the coating amount of the emulsion used in the coating method described above to obtain a coated molding material having good fluidity and sufficient anti-adhesive effect is sufficient to be 100 to 5000 ppm based on the molding material. Depending on the situation, even higher concentration deposition is possible and will not cause any problems. According to the present invention, various problems of conventional anti-adhesive agents can be improved, the amount used is extremely small, it has good fluidity, and it also provides a sufficient anti-adhesive effect to the molding material. It has the advantage of being able to In addition, since the emulsion used in the present invention is aqueous, it is extremely safe and has the great advantage of being easy to handle, such as being able to freely adjust its concentration. In addition, the coating method using this emulsion is extremely easy to adapt to the conventional pellet manufacturing process, and is also effective in improving the fluidity and preventing adhesion of the coated molding material manufactured by this method. It has extremely high advantages. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. The evaluation method and evaluation criteria for the properties of the coated molding material described in the examples are as follows. 1. Fluidity Put 200g of resin pellets that have undergone various anti-adhesion treatments into a fluidity measurement funnel (upper diameter 130mm, lower diameter 30mm, angle of repose 60° conical funnel).
The fluidity was classified into the following ranks based on funnel passage time and passage conditions. A: The resin pellets flow down extremely smoothly, with no retention or clogging. B: Although the resin pellets flow down, they cause some stagnation and clogging, and it takes time for the resin pellets to flow down. C: It does not flow down at all, or it flows down a little by applying an external force from the upper part of the funnel, but it becomes clogged again. 2 Blocking resistance 100g of pellets treated with each anti-stick treatment were placed in a square-shaped container with internal dimensions of 60mm x 60mm x 70mm.
After placing a load of 7 kg on the pellets and leaving them in an oven set at 40°C or 35°C for 48 hours, the pellets were taken out of the oven and conditioned at 23°C for 24 hours. We observed the force required to compress and break the material and its blocking status, and determined the following ranks. A: No blocking. B: Light blocking that breaks down relatively easily. C: Strong blocking. 3 Solubility A toluene solution of the pellets prepared by dissolving 50 g of each anti-adhesive pellet in 230 ml of toluene was compared, and the appearance was compared to determine the following ranks. A: Clear solution without suspension. B: Slightly cloudy solution. C: Severely cloudy solution. Example 1 Maleic anhydride and acrylic acid were added to EVA with a vinyl acetate content of 32% by weight and a melt index of 30g/10 minutes, and the mixture was polymerized using an organic peroxide polymerization initiator, resulting in a viscosity of 180 cp. /25℃, acid value 65
EVA with a vinyl acetate content of 40 wt% and a melt index of 65 g/10 min was dissolved in a 15 wt% toluene solution of mgKOH/g carboxylated EVA, water and ammonia were added, and the mixture was placed in a vacuum homomixer. Obtained by strong stirring, solid concentration 13% by weight, average particle size 5-10μ, 85% of the carboxylic acid.
Using a neutralized carboxylated EVA aqueous emulsion, a diluted aqueous solution of the emulsion with a solids dispersion concentration of 1% by weight was prepared. In 1 kg of this solution,
After soaking 500 g of EVA pellets with a vinyl acetate content of 40% by weight, they were filtered through a 5-mesh stainless steel screen.
Water was removed in a centrifuge and dried. The fluidity, blocking resistance, and solubility of the pellets obtained in this way were evaluated, and the amount of solid matter deposited was evaluated in the first step.
Shown in the table. Comparative example 1 Melt index 22g/10 minutes, average particle size
Using 20μ powdered polyethylene, an aqueous dispersion with a solids dispersion concentration of 1% by weight was prepared, EVA pellets similar to those used in Example 1 were immersed, and the same treatment as in Example 1 was performed. Coated EVA pellets were made. Table 1 shows the evaluation of the fluidity, blocking resistance and solubility of the pellets thus obtained, as well as the amount of solid matter deposited.

[Table] As a result of coating using aqueous solutions with the same dispersion concentration, as is clear from Table 1, Example 1 had a larger amount of solid matter attached, and also had significantly improved fluidity and blocking resistance, and had a higher solubility. You can see that it is not damaged either. Example 2 In the same manner as in Example 1, using an aqueous emulsion in which EVA with a vinyl acetate content of 32% by weight and a melt index of 30 g/10 minutes was dissolved in a toluene solution of carboxylated EVA prepared in the same manner as in Example 1. A coated EVA pellet was prepared. The fluidity, blocking resistance, and solubility of the pellets obtained in this way were evaluated, and the amount of solid matter deposited was
Shown in the table. Example 3 Carboxylation prepared as in Example 1
EVA and molecular weight 2000, density 0.92g/cm ³ , softening point
Carboxylated EVAA aqueous emulsion (solids concentration 10 wt.,
EVA pellets to be coated were obtained in the same manner as in Example 1 by adjusting the average particle size (5 to 10 μm). Table 2 shows the evaluation of the fluidity, blocking resistance and solubility of the pellets obtained, as well as the amount of solid matter deposited. Comparative Example 2 Molecular weight 4000, density 0.92g/cm ³ , softening point 13℃ (JIS
K2531 ring and ball method) polyethylene wax dispersed in water, average particle size 5μ, solid concentration 40% by weight
Using this aqueous dispersion, an aqueous solution having a solid dispersion concentration of 1% by weight was prepared, and EVA pellets to be coated were prepared in the same manner as in Example 2. Table 2 shows the evaluation of the fluidity, blocking resistance and solubility of the pellets thus obtained, as well as the amount of solid matter deposited.

[Table] As is clear from Table 2, in Comparative Example 2, some effect on blocking resistance was observed, but it was found that fluidity and solubility were significantly inferior. In contrast, Examples 2 and 3
Good fluidity and anti-blocking properties were obtained without impairing solubility. Example 4 Carboxylation similar to that used in Example 1
Using EVA aqueous emulsion, solid dispersion concentration
A 10% by weight aqueous emulsion solution was prepared, and in 1 kg of this solution, 70 parts by weight of EVA (20 parts by weight of Ultrasen 634, 50 parts by weight of Ultrasen 750, manufactured by Toyo Soda Kogyo Co., Ltd.) and adhesive After immersing 500 g of hot melt composition pellets obtained by blending 30 parts by weight of imparting agent (trade name Bencel C, manufactured by Arakawa Chemical Co., Ltd.), the pellets were filtered through a 5-mesh stainless steel screen and placed in a centrifuge. Water was removed and dried. Table 3 shows the evaluation of the fluidity, blocking resistance and solubility of the pellets thus obtained, as well as the amount of solid matter deposited. Comparative example 3 Molecular weight 4000, density 0.97g/cm ³ , softening point 128℃
All examples are examples except that an aqueous dispersion of polyethylene wax (JISK2531 ring and ball method) dispersed in water with an average particle size of 5μ and a solids concentration of 42% by weight was used, and an aqueous solution with a solids concentration of 10% by weight was prepared. A hot melt composition pellet to be coated was prepared in the same manner as in Example 3. Table 3 shows the evaluation of the fluidity, blocking resistance and solubility of the pellets thus obtained, as well as the amount of solid matter deposited.

[Table] As is clear from Table 3, in Example 4, pellets having the desired good fluidity were obtained without impairing any properties. However, in Comparative Example 3, the solubility was lost. Comparative Examples 4 and 5 Average particle size is 80-130μ (Comparative Example 4) and 0.1-1μ
(Comparative Example 5) The same carboxylated EVA aqueous emulsion as in Example 1 was prepared, and EVA pellets to be coated were prepared in the same manner as in Example 1. The evaluation of fluidity, blocking resistance, and solubility of the pellets thus obtained, as well as the amount of solid matter deposited, were compared with those of Example 1 and are shown in Table 4.

[Table] As is clear from Table 4, the particle size range of the aqueous emulsion has a significant effect on the fluidity and blocking resistance of the pellets to be coated, and is an important factor in the application.

Claims (1)

[Scope of Claims] 1. On the surface of an ethylene-vinyl acetate copolymer molding material or a hot melt composition molding material containing an ethylene-vinyl acetate copolymer as a component thereof, in the presence of an ethylene-vinyl acetate copolymer, A carboxylated ethylene-vinyl acetate copolymer that has neutralized 50 chemical equivalents or more of the carboxylic acid in the copolymer obtained by copolymerizing maleic anhydride and acrylic acid, and an ethylene-vinyl acetate copolymer or A molding material coated with a covering material made of wax. 2. The surface of an ethylene-vinyl acetate copolymer molding material or a hot melt composition molding material containing an ethylene-vinyl acetate copolymer as a component thereof is treated with maleic anhydride and acrylic acid in the presence of an ethyne-vinyl acetate copolymer. 50 chemical equivalents of carboxylic acid in the copolymer obtained by copolymerizing
A method for producing a resin molding material, which comprises coating with an aqueous emulsion of ethylene-vinyl acetate copolymer or wax, which uses a neutralized carboxylated ethylene-vinyl acetate copolymer as an emulsifier. 3. The manufacturing method according to claim 2, wherein the emulsion has a solid content concentration of 1 to 40% by weight. 4. The manufacturing method according to any one of claims 2 to 3, wherein the emulsion has an average particle size of 3 to 70 microns. 5. The manufacturing method according to any one of claims 2 to 4, wherein the emulsion has an average viscosity of 1 to 1000 cp.