KR20040077476A - Ethylene copolymer pellets - Google Patents

Abstract

PURPOSE: An ethylene copolymer pellet is provided, to reduce the blocking of an ethylene copolymer pellet by using a specific lubricant. CONSTITUTION: The ethylene copolymer pellet comprises 100 parts by weight of an ethylene copolymer; 0.01-0.5 parts by weight of an unsaturated fatty acid bisamide having a melting point of 100-180 deg.C; and 0.01-0.5 parts by weight of a lubricant having a melting point of 60-90 deg.C which decreases the melting point of the unsaturated fatty acid bisamide by 20 deg.C or more when used in combination with the ethylene copolymer and the unsaturated fatty acid bisamide. Preferably the ethylene copolymer is a ethylene-vinyl acetate copolymer; the unsaturated fatty acid bisamide is ethylene bisoleic acid amide; the lubricant is an unsaturated fatty acid amide; and the pellet is a mixture obtained by melting mixing.

Description

Ethylene Copolymer Pellets {ETHYLENE COPOLYMER PELLETS}

The present invention relates to ethylene copolymer pellets with improved prevention of fusion bonding of pellets (hereinafter referred to as "pellet blocking").

Pellets of ethylene copolymers such as ethylene / vinyl acetate copolymers (hereinafter referred to as "EVA") are firmly blocked from each other during pellet production or subsequent storage and transportation due to their high tack and the like. In addition, the pellets have a problem in that due to the very poor fluidity, a lot of effort is required for pellet production and packaging. It was also difficult for long time storage and transportation. As a technique for solving these problems, various pellet processing methods have been proposed so far.

Pellet blocking prevention techniques, comprising: coating a surface of a pellet with an inorganic material such as talc or silica, polyolefin fine particles, polyethylene wax, or a dispersion thereof; And higher fatty acids or salts thereof, N, N'-ethylenebisoleic acid amide, N, N'-ethylenebiserucaic acid amide, N, N'-dioleoyladipic acid imide, or N, N'-dielusyl The method of mixing adipic acid imide is enumerated. However, these various methods have many problems.

For example, when inorganic materials such as talc or silica are mixed with EVA and adhered, it is necessary to add a large amount of inorganic material to obtain fluidity of the pellets. However, the use of such a large amount of inorganic material, there is a problem that seriously impairs the function of the final product due to poor compatibility with EVA.

The method of coating polymer pellets with an aqueous slurry of polyolefin fine particles has a very poor dispersibility in the aqueous system, and since the tendency to adhere to the pellets is poor, this technique substantially eliminates adhesion and is satisfactory. It has a problem that it cannot reach the level of securing liquidity (see US Pat. No. 3,528,841).

When EVA pellets are coated with a dispersion containing polyethylene wax as a main component, polyethylene wax, or the like, although the method is effective in removing some tack, practical fluidity cannot be obtained. This method also has the problem that when the coated pellets are melted, the melt becomes milky white. For this reason, pellets coated by the above technique have limited uses (Japanese Patent Laid-Open No. 56-67209).

In addition, when pellets of high-adhesive ethylene polymer are coated with a dispersion of low-adhesive EVA, this depends on the vinyl acetate content in the coating material, but is substantially eliminated since the EVA used as the coating material has a low melting point. There is a problem in that coated pellets with a sufficient adhesiveness and sufficient fluidity cannot be obtained (Japanese Patent Laid-Open No. 48-32939).

A method of mixing a high fatty acid or a salt thereof (e.g., Japanese Patent Application Laid-Open No. 56-136347) and N, N'-ethylenebisoleic acid amide, N, N'-ethylenebiserucaic acid amide, N, N'- A method of containing an additive selected from the group consisting of dioleyl adipic acid imide and N, N'-dielusyl adipic acid imide (Japanese Patent Laid-Open No. 57-200434) has been proposed. However, these methods have the drawback that the effect of preventing the initial pellet blocking is poor because the bleed rate of the additive is insufficient.

It is therefore an object of the present invention to provide ethylene copolymer pellets with improved prevention of pellet blocking.

The present inventors made intensive research in consideration of these problems. As a result, it has been found that the blocking of ethylene copolymer pellets can be reduced by adding a specific lubricant to the ethylene copolymer. The present invention has been accomplished based on this finding.

The present invention relates to ethylene copolymer pellets comprising the following mixture.

(a) 100 parts by weight of ethylene copolymer;

(b) 0.01 to 0.5 parts by weight of unsaturated fatty acid bisamide having a melting point of 100 to 180 ° C; And

(c) 0.01 to 0.5 parts by weight of a lubricant having a melting point of 60 to 90 ° C. which reduces the melting point of component (b) by 20 ° C. or more when used in combination with component (b).

Hereinafter, the present invention will be described in detail.

The ethylene copolymer (a) used in the present invention is not particularly limited, and examples thereof include ethylene / α, β-unsaturated carboxylic acid ester copolymers, ethylene / vinyl ester copolymers, ethylene / vinyl esters / α, β And polymers called ethylene copolymers such as -unsaturated carboxylic acid terpolymers and ethylene / α-olefin copolymers. Specific examples of the ethylene copolymers include ethylene / vinyl acetate copolymers, ethylene / ethyl acrylate copolymers, ethylene / methyl methacrylate copolymers, ethylene / ethyl methacrylate copolymers, ethylene / 1-butene copolymers, Ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer, ethylene / 4-methyl-1-pentene copolymer, ethylene / propylene copolymer rubber, ethylene / propylene / diene copolymer rubber, and ethylene / butene copolymer Rubber is listed. Of these, preference is given to using ethylene / vinyl acetate copolymers having a low softening point.

Ethylene / vinyl having a vinyl acetate content of 27-50 wt%, measured according to JIS K6924-1 (1997), and a melt flow rate (MFR) measured according to JIS K6924-1 (1997) satisfying the following relationship: More preferred are acetate copolymers.

MFR> 431.98 X (VAc) ^-0.7731

As such, ethylene / vinyl acetate copolymers that tend to be easily blocked (ie, have high VAc content and high MFR) are preferred.

The unsaturated fatty acid bisamide (b) used in the present invention has a melting point of 100 to 180 ° C. Examples of unsaturated fatty acid bisamides (b) include ethylenebisstearic acid amide, ethylenebisoleoleic acid amide, ethylenebiserucaic acid amide, and ethylenebislauric acid amide. Among them, it is preferable to use ethylenebisoleic acid amide from the viewpoint of compatibility with the ethylene copolymer and bleeding property.

The unsaturated fatty acid bisamide (b) is used in an amount of 0.01 to 0.5 parts by weight, preferably 0.05 to 0.2 parts by weight, per 100 parts by weight of the ethylene copolymer (a). When the amount of the unsaturated fatty acid bisamide (b) used is less than 0.01 part by weight, the blocking prevention effect of the pellets is inferior. On the other hand, when the amount exceeds 0.5 parts by weight, the unsaturated fatty acid bisamide (b) is bleed out to the surface in a large amount due to the time, such as a problem that the adhesive strength is reduced.

When the lubricant (c) used in the present invention is used in combination with an unsaturated fatty acid bisamide (b), a lubricant having a melting point of 60 to 90 ° C, which reduces the melting point of the unsaturated fatty acid bisamide (b) by 20 ° C or more. It is not specifically limited. Examples of lubricants (c) include fatty acids and fatty acid amides. When melting | fusing point of the said lubricant (c) is lower than 60 degreeC, the blocking prevention effect of a pellet will fall. On the other hand, when melting | fusing point exceeds 90 degreeC, the initial blocking prevention effect of a pellet is inadequate. Specific examples of the lubricant (c) include saturated fatty acids such as stearic acid, palmitic acid or behenic acid, and unsaturated fatty acid amides such as erucic acid amide or oleic acid amide. These compounds may be used alone or in combination thereof. Among the lubricants, it is preferable to use unsaturated fatty acid amides which move to the surface quickly and have excellent anti-blocking performance, and more preferably, erucanoic acid amides having improved bleedability of the unsaturated fatty acid bisamides (b).

The lubricant (c) is used in an amount of 0.01 to 0.5 parts by weight, preferably 0.05 to 0.2 parts by weight, per 100 parts by weight of the ethylene copolymer (a). When the amount of the lubricant (c) is less than 0.01 part by weight, the blocking prevention effect of the pellets is inferior. On the other hand, if the amount exceeds 0.5 parts by weight, the lubricant may be bleed out on the surface in a large amount due to the elapse of time, resulting in a decrease in adhesive strength.

The weight ratio (a) / (b) of the unsaturated fatty acid bisamide (b) to the lubricant (c) is preferably 70/30 to 30/70 from the bleeding point of the unsaturated fatty acid bisamide (b).

In the present invention, the method of adding the lubricant (c) is not particularly limited, and a method that is arbitrarily required can be used to obtain pellets. Examples of the method include melt kneading the components with an extruder, a Banbury mixer, a kneader, or the like; Coating the surface of the pellets with a lubricant in the form of a dispersion or the like; And how the lubricant is dry mixed with the pellets. Pellets obtained by melt kneading are preferable because they have excellent prevention against blocking.

As for the ethylene copolymer pellet which concerns on this invention, the surface roughness Ra measured according to JIS B0601 (1994) has preferable 1.0-2.5 micrometers from a viewpoint of a blocking prevention effect, fluidity | liquidity, etc. As a method for roughening the surface which can be used in the present invention, the pellets obtained by cutting such as underwater cutting, strand cutting, or hot cutting may be used for transport piping (knurling) or annular pattern having irregularities arranged in a lattice pattern. There exists a method of letting a transportation piping (eco) which has an uneven part arranged in this manner pass.

Surface roughness Ra which concerns on this invention is a value obtained using the color laser microscope VK-8500 (made by Keyence Corporation).

If necessary, the ethylene copolymer pellet of the present invention may contain pigments, dyes, antioxidants, lubricants, weathering agents, antiblocking agents, various stabilizers, inorganic fillers and the like.

(Example)

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

In the following examples and comparative examples, experiments for performance evaluation were carried out in the following manner.

(1) pellet blocking experiment

100 g of ethylene copolymer pellets obtained by melt kneading were placed in a test piece preparation box having an internal dimension of 60 × 60 × 60 mm. With a load of 68.6N on it, the box was left at 30 ° C. for 48 hours and then left at 23 ° C. for 24 hours. The obtained test piece was compressed at a rate of 10 mm / min to determine the maximum load required for breakage. In addition, the same experiment was performed for ethylene copolymer pellets left under 23 ° C. atmosphere for 1 month. Test specimens exhibiting blocking strength of less than 490 N are indicated as "good", while those exhibiting blocking strength of 490 N or more are designated as "poor". The results of these experiments are shown in Table 2.

(2) Measurement of melting point decrease

The unsaturated fatty acid bisamide (b) was tested by DSC curve and the temperature corresponding to the peak top on the highest melting point side of the curve was Tm1. The mixture of the unsaturated fatty acid bisamide (b) and the lubricant (c) melt kneaded was experimented by DSC curve, so that the temperature corresponding to the peak top on the highest melting point side of the curve was Tm2. The difference between Tm1 and Tm2 was the melting point reduction. This demonstration result is shown in Table 2.

Example 1

According to the formulation shown in Table 1, 0.1 part by weight of 100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corp.) having an MFR of 400 g / 10 minutes and a VAc content of 33 wt% Melt kneading was performed with ethylenebis oleic acid amide and 0.1 parts by weight of erucic acid amide. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The melting point of ethylenebisoleic acid amide, Tm1, was 120 ° C, while the melting point of erucic acid amide was 82 ° C. The melting point, Tm 2, of the mixture of ethylenebisoleic acid amide and erucic acid amide 50/50 (wt%) was 75 ° C. The results of the melting point reduction measurement and the blocking strength measurement are shown in Table 2.

Kinds MFR (g / 10 min) Comonomer content (wt%) Unsaturated fatty acid bisamide Amount (part by weight) slush Amount (part by weight) How to add Surface Roughness (㎛) Example 1 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.1 Erucic acid amide 0.1 Melt kneading 1.6 Example 2 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.5 Erucic acid amide 0.5 Melt kneading 1.6 Example 3 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.05 Erucic acid amide 0.05 Melt kneading 1.6 Example 4 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.1 Oleic acid amide 0.1 Melt kneading 1.6 Comparative Example 1 EVA 400 33 - - - - - 1.6 Comparative Example 2 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.2 - - Melt kneading 1.6 Comparative Example 3 EVA 400 33 - - Erucic acid amide 0.2 Melt kneading 1.6 Comparative Example 4 EVA 400 33 Ethylene Bis Oleic Acid Amide 0.15 Erucic acid amide 0.05 Melt kneading 1.6

Tm1 (℃) Tm2 (℃) Melting Point Reduction (℃) Blocking Strength (N) Right after 1 month later Example 1 120 75 45 206 Good 186 Good Example 2 120 75 45 78 Good 59 Good Example 3 120 75 45 441 Good 392 Good Example 4 120 85 35 294 Good 274 Good Comparative Example 1 - - - > 490 Bad > 490 Bad Comparative Example 2 - - - > 490 Bad 314 Good Comparative Example 3 - - - > 490 Bad > 490 Bad Comparative Example 4 120 103 17 > 490 Bad 196 Good

Example 2

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corporation) having a MFR of 400 g / 10 min and a VAc content of 33 wt% was 0.5 parts by weight of ethylenebisoleic acid amide and 0.5 parts by weight. Melt kneading with erucic acid amide. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The results are shown in Table 2.

Example 3

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corporation) having a MFR of 400 g / 10 minutes and a VAc content of 33 wt% was prepared by 0.05 parts by weight of ethylenebisoleic acid amide and 0.05 parts by weight of Melt kneading with erucic acid amide. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The results are shown in Table 2.

Example 4

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corporation) having a MFR of 400 g / 10 minutes and a VAc content of 33 wt% was prepared by 0.05 parts by weight of ethylenebisoleic acid amide and 0.05 parts by weight of Melt kneading with oleic acid amide. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. Table 2 shows the results of the melting point reduction measurement and the blocking strength measurement for the mixture of 0.1 parts by weight of ethylenebisoleic acid amide and 0.1 parts by weight of oleic acid amide.

Comparative Example 1

The pellet surface of the ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corporation) having a MFR of 400 g / 10 min and a VAc content of 33 wt% was roughened. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The results are shown in Table 2. The pellets are impractical due to their high blocking strength.

Comparative Example 2

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corp.) having a MFR of 400 g / 10 minutes and a VAc content of 33 wt% was melt kneaded together with 0.2 parts by weight of ethylenebisoleic acid amide. I was. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The results are shown in Table 2. Immediately after fabrication, the pellets are impractical due to their high blocking strength.

Comparative Example 3

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corp.) having a MFR of 400 g / 10 minutes and a VAc content of 33 wt% was melt kneaded together with 0.2 parts by weight of erucic acid amide. I was. The mixture was then cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. The results are shown in Table 2. The pellets are impractical due to their high blocking strength.

Comparative Example 4

100 parts by weight of ethylene / vinyl acetate copolymer (ultracene (Nipoplex) 0B54B, manufactured by Tosoh Corporation) having a MFR of 400 g / 10 minutes and a VAc content of 33 wt% was 0.15 parts by weight of ethylenebisoleic acid amide and 0.05 part by weight. Melt kneading with erucic acid amide. The mixture thus obtained was cut by underwater cutting. The surface of the obtained pellet was rough. In this way, a pellet having a surface roughness Ra of 1.6 µm was obtained. The blocking strength of the obtained pellets was evaluated. Table 2 shows the results of the melting point reduction and the blocking strength measurement for the mixture of 0.15 parts by weight of ethylenebisoleic acid amide and 0.05 parts by weight of erucic acid amide. Immediately after fabrication, the pellets are impractical due to their high blocking strength.

As mentioned above, the ethylene copolymer pellets according to the present invention may have improved blocking resistance.

Claims (9)

(a) 100 parts by weight of ethylene copolymer; (b) 0.01 to 0.5 parts by weight of unsaturated fatty acid bisamide having a melting point of 100 to 180 ° C; And (c) an ethylene comprising a mixture of 0.01 to 0.5 parts by weight of a lubricant having a melting point of 60 to 90 ° C. which reduces the melting point of component (b) by 20 ° C. or more when used in combination with component (b). Copolymer pellets. The ethylene copolymer pellets according to claim 1, which is a mixture obtained by melt kneading. The ethylene copolymer pellet according to claim 1 or 2, wherein the ethylene copolymer is an ethylene / vinyl acetate copolymer. The melt flow rate according to claim 1 or 2, wherein the ethylene copolymer has a vinyl acetate VAc content of 27 to 50 wt%, measured according to JIS K6924-1 (1997). Ethylene copolymer pellets, characterized in that the rate, MFR, is an ethylene / vinyl acetate copolymer having a value satisfying the following relationship. MFR> 431.98 X (VAc) ^-0.7731 The ethylene copolymer pellets according to claim 1 or 2, wherein the weight ratio of the unsaturated fatty acid bisamide (b) to the lubricant (c) is 70/30 to 30/70. The ethylene copolymer pellets according to claim 1 or 2, wherein the unsaturated fatty acid bisamide (b) is ethylenebisoleic acid amide. The ethylene copolymer pellets according to claim 1 or 2, wherein the lubricant (c) is an unsaturated fatty acid amide. 8. The ethylene copolymer pellets of claim 7, wherein the unsaturated fatty acid amide is an erucic acid amide. The ethylene copolymer pellets according to claim 1 or 2, wherein the surface roughness Ra measured according to JIS B0601 (1994) is 1.0 to 2.5 µm.