JPS6329893B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to non-stick polymer pellets, such as ethylene/vinyl acetate copolymer pellets, which have good handling properties and resistance to sticking. For purposes of this invention, the term "vinyl acetate copolymers" shall include ethylene and vinyl acetate dipolymers, as well as terpolymers that also include carbon monoxide. Ethylene/vinyl acetate copolymer (EVA) is
Flexible, heat-sealable, functional and decorative hot-melt, solvent-based coatings, such as wax additives to impart toughness; compounding resins to impart flexibility to brittle materials; and high temperature It is widely used industrially as a component of adhesives that are melted and used in a solvent. Most industrial EVA bipolymers are approximately 2 to 55
Contains % vinyl acetate by weight. The terpolymer of ethylene, vinyl acetate and carbon monoxide is about 18~
Contains 40% by weight vinyl acetate and 2-12% by weight carbon monoxide. Bipolymers of ethylene and vinyl acetate are available from E.I. DuPont, Wilmington, Delaware, USA.
Des Nemoise & Company (E.I.
du Pont de Nemours and Company under the trade name "Elvax," and the carbon monoxide-containing terpolymer is commercially available from Hammer, U.S. Pat. No. 3,780,140 and Brubaker, U.S. Pat. It can be made according to Patent No. 2495286. As the vinyl acetate content of the copolymer increases, the tackiness of the copolymer increases. Pellets of the copolymer, in its usual commercial form, tend to clump together, ie stick together, forming large agglomerates, especially when pressed under their own weight at moderately high temperatures. This tackiness and cohesiveness also increases with the melting coefficient of the copolymer, ie, as the molecular weight decreases. For example, bulk EVA copolymers containing about 25-30% by weight of vinyl acetate experience this type of problem when the melt coefficient exceeds 6 g/10 minutes. However, even such copolymers have different fluidity and cohesiveness depending on their melting coefficients. For example, a copolymer with a melting coefficient of about 50 g/10 minutes or less can be shipped in a 26.65 kg bag or a 500 kg box without clumping. Melting coefficient is approximately 100
Copolymers exceeding g/10 min cannot be shipped in large containers without the risk of clumping, but can be packaged in bags. All of these copolymers are free-flowing and can be easily handled. High content of vinyl acetate, e.g. about 35% by weight
These copolymers are very sticky, have poor flow properties, and tend to clump even in regular sized bags. Most EVA copolymers with higher vinyl acetate content cannot be shipped in hoppers. Other polymers that have similar difficulties, particularly during shipping and storage, are copolymers of ethylene and methacrylic acid, in which the carboxyl groups are free or partially neutralized with metal ions;
It is also a dipolymer of ethylene and methyl methacrylate. The copolymer of ethylene and methacrylic acid is "Surlyn" from E.I. Dupont.
It is commercially available under the trade name "Surlyn". This copolymer is a partially neutralized ionic polymer (ionomer). The substrate resin (a non-neutralized copolymer) is also manufactured by DuPont, but is only available commercially in limited quantities. Copolymers of ethylene and methyl methacrylate may be made by the methods of Stuetz, U.S. Pat. No. 3,287,335, Knudson et al., U.S. Pat. No. 3,658,741, and Agouri et al., U.S. Pat. No. 3,949,016. Can be done. A particularly serious problem that occurs in equipment for pelletizing and packaging sticky polymers, particularly some ethylene/vinyl acetate copolymers, is that the pellets stick to each other and to the equipment, resulting in suboptimal process flow rates. This is a decrease in If the pellets cannot be handled at normal process speeds, or at all, the efficiency of the process is significantly reduced. Although all of the polymers used in this invention have a tendency to clump when stored in pellet form, not all have the handling difficulties and poor flow properties described above. Attempts have been made to improve the flowability of EVA copolymer pellets and reduce their tendency to stick together, in particular by coating the pellets with various materials such as clay, talc or powdered polyethylene. See, eg, US Pat. No. 3,528,841 to Donaldson et al. Although these methods are reasonably effective, they do not always completely prevent agglomeration of the pellets that occurs before the coating is applied, and the coating does not adhere to the pellets indefinitely; It has the disadvantage of being lost. Slip (anti-stick) agents are commercially available to improve the slip of polymeric films and the processability of polymers. These include, for example, various fatty acids, which, although most effective with some polymers of other types, have little or no effect on reducing the stickiness of EVA pellets. Not effective at all. According to the invention, (a) a bipolymer of ethylene and vinyl acetate in which the amount of vinyl acetate is about 18-55% by weight; (b) the amount of vinyl acetate is about 20-40% by weight and carbon monoxide; (c) a terpolymer of ethylene, vinyl acetate and carbon monoxide in an amount of about 3 to 12% by weight; (c) an amount of methacrylic acid in an amount of about 6 to 30% by weight; 0 to approx.
(d) a copolymer of ethylene and methyl methacrylate, the amount of methyl methacrylate being about 18 to 40% by weight; The tendency of the pellets of selected polymers to clump is determined by the addition of additives selected from the group consisting of N,N'-ethylenebisoleamide and N,N'-ethylenebiserucamide with respect to the weight of the polymer.
It has been found that by incorporating effective amounts of 500 to about 10,000 ppm, especially 1,000 to 5,000 ppm, before pelletizing, it can be significantly reduced, ie the free-flowing properties of the pellets are significantly improved. N,N'-ethylenebisoleamide, a preferred additive from Carstab, Reading, Ohio, USA under the trade name Advawax 240; from Humko SheHield, Memphis, Tennessee, USA under the trade name ``Kemamide''. )” under the trade name W-20; also sold by Glyco Chemical of Greenwich, Connecticut, USA.
It is commercially available under the trade name ``Glycolube'' VL from the Chemical Company.
These products have a melting point range of 113-118°C and are insoluble in most industrial solvents. It is recommended by the manufacturer as a processing lubricant and antiblocking agent for various polymers and copolymers, especially as a slip agent for films. The recommended concentration is 0.5-2%.
Other additives can be made from readily available materials by known methods. That is, ethylene biserucamide is produced by heating 1,2-ethylenediamine and erucic acid. The additive of the present invention travels through the interior of the polymer pellet until it reaches the surface. In other words, it is thought that he possesses a special ability that exudes. The resulting layer of additive on the surface of the pellet is responsible for improving the properties of the pellet, but all four additives do not move at the same speed. N,N'-ethylene bis-oleamide migrates almost instantaneously to the surface of the EVA copolymer pellet, whereas the migration rate of N,N'-ethylene bis-erucamide is much slower. Therefore, N,N'-ethylenebisoleamide has a remarkable effect in reducing tackiness and improving handling properties and flow characteristics. However, if time is not critical, all four additives are effective. The effectiveness of antiblocking agents can be evaluated in a variety of ways, but the best test, of course, is actual storage over an extended period of time. The feel of pellets made from the polymer can be judged, and should be smooth without being sticky. EVA containing about 25-30% vinyl acetate by weight
For copolymers, as well as most other polymers, tack temperature is a useful measurement. Although a lower tack temperature does not necessarily mean that the pellet has a greater tendency to stick, a higher tack temperature usually indicates a less tendency for the pellet to stick. Laboratory adhesion test methods have been considered for copolymers with high vinyl acetate content. Improved handling and packaging properties in actual production are good indicators of good sliding properties, especially for copolymers with high vinyl acetate content. The amides and imides of the present invention can be prepared in any convenient manner, such as melt, dry powder below the melting temperature,
Or it can be added to the copolymer as a concentrate in the same or any compatible polymer. The additives are thoroughly blended with the polymer and the polymer is then extruded into pellets. Additives are 1000-5000ppm,
In particular, it is preferable to use it at 2000 to 4000 ppm. Therefore, lower concentrations will not improve the sliding properties sufficiently, whereas higher concentrations will reduce other properties, such as the adhesion of the copolymer. The EVA copolymer is sometimes blended with a small amount of paraffin wax, about 2-13%. When the amide or imide of the present invention is added to such a wax-containing copolymer, the antiblocking properties are improved. As stated above, the amount of additive is relative to the weight of the EVA. The present invention will now be illustrated in representative embodiments thereof, in which all proportions are by weight. All formulations were made in an extruder and the water cooled melt was cut into pellets. The rate at which the two additives of the invention migrate to the surface of the pellets was determined as follows. A 100-200 g sample of freshly water-cooled and cut pellets is centrifuged in a wire cage for 30 seconds and the pellets are spun dry. Stop the centrifuge, remove the wire basket, and turn it downward. The total time from cutting into pellets to this point should be no more than 2.5 minutes. Ethylene containing approximately 40% vinyl acetate and no additives/
Although vinyl acetate dipolymer does not fall from the basket,
The material containing 3000 ppm N,N'-ethylenebisoleamide is free-flowing. same concentration of N,
For the sample containing N'-ethylene biserucamide, the time to free flow is 45 minutes. Similarly,
An ethylene/vinyl acetate/carbon monoxide terpolymer containing 28% vinyl acetate, 9% carbon monoxide, and a melting coefficient of 35 g/10 minutes was not free-flowing without additives. A sample containing 4000 ppm of N,N'-ethylenebisoleamide is removed from the wire cage and turned free-flowing. If N,N'-ethylene biserucamide is used instead, the additive transfer time is 30 minutes. Stick temperature testing measures the tendency of a polymer pellet to flow after being held at a certain temperature and pressure for a certain period of time. Sticking temperature is defined as the highest temperature at which all polymer flows from the test vessel within 1 minute. The polymer pellets are placed in a vertical tube lined with poly(ethylene terephthalate) film having an inner diameter of 3.9 cm and a length of 23.2 cm. on top of pellets
Place a 4086g weight on it and make the downward pressure 33.5KPa. Hot air is passed upward for 15 minutes at a rate of 11 cm ³ /min, followed by ambient temperature air for 5 minutes. Next, remove the weight and turn the tube upside down. Record the time when all pellets flow out of the tube. This test is repeated at gradually increasing temperatures until only some or no copolymer flows out of the tube. The sticking temperature is the final temperature at which all pellets have flowed out. The stickiness temperature of a given EVA copolymer depends to some extent on the shape of the pellet size. Small, non-round pellets stick together more easily than large round pellets. Therefore, it is important to perform control experiments for each adhesion temperature measurement. All pellets used in the following examples were 1.8 to 3.2 g per 10 pellets.
It was shaped like a pillow. Example 1 A concentrate containing 5% N,N'-ethylenebisoleamide in an EVA bipolymer containing 28% vinyl acetate and a melting coefficient of 150 g/10 min was prepared in a reactor.
Melt the EVA binary polymer at 220°C under nitrogen,
It was made by adding the required amount of bis-oleamide. Heat the concentrate, stirring occasionally until homogeneous, pour it onto a plate and grind. 1000, 2000 and 3000ppm bisoleamide respectively
A blend of EVA bipolymer containing 28% vinyl acetate with a melting coefficient of 150 g/10 min and the concentrate described above was prepared. These formulations had a distinct smooth texture. The following values were obtained for the adhesion temperature. EVA copolymer control 30.1°C 1000ppm blend 36.7°C 2000ppm blend 36.5°C 3000ppm blend 40.7°C The sticking temperature of a similarly prepared blend containing N,N'-bisethylene erucamide at 3000 rpm was 38°C. It was hot. Example 2 EVA bipolymers with melting coefficients of 150, 43, and 25 g/10 min, respectively, and a vinyl acetate content of 28% were prepared in Example 1.
Combined with bisoleamide/EVA concentrate,
Bisoleamide concentrations of 3000 ppm, 4000 ppm, and 5000 ppm are prepared and pelletized as described above. All of these formulations have a smooth feel, whereas the EVA copolymer control does not have that feel. The following sticking temperatures were obtained for the 3000 ppm formulation and the EVA copolymer control. EAV bipolymer Sticking temperature (°C) Melt coefficient Control product Compound 150 32 34 43 30 36 25 30 38 Example 3 Melt coefficient is 150 g/10 min, vinyl acetate content is 28
% EVA dipolymer and the N,N'-ethylene bisoleamide/EVA concentrate of Example 1 were made to form formulations containing 3000 and 5000 ppm bisoleamide. All had a smooth feel, but the sticking temperature was close to that of the control copolymer. Three types of commercially available N,
Six samples containing the same concentration of N'-ethylene bisstearamide were also prepared. These samples did not have a slick feel and their sticking temperatures were close to the control. Weighing errors may occur in the case of bis-oleamide, so that the actual amount of the additive may be less than expected. Example 4 Melting coefficient: approx. 57 g/10 min, vinyl acetate content: approx. 40%
A concentrate containing 25% N,N'-ethylenebisoleamide in EVA dipolymer was prepared. Melt coefficient: approx. 57g/10 min, vinyl acetate content: approx. 40%
of EVA bipolymer with the above 25% concentrate,
A homogeneous formulation containing 5000 ppm bisoleamide was created. Samples of 908 g each of this formulation, the reextruded EVA bipolymer, and a commercially available clay-coated EVA bipolymer with the same melt coefficient and vinyl acetate content were air-dried at 40°C for 16 hours. .
The sample containing bisoleamide flowed freely from the small bag, while the other two samples clogged significantly. Example 5 Melting coefficient: approx. 57 g/10 min, vinyl acetate content: approx. 40%
Samples of 9.08 kg each of EVA dipolymer were prepared. These samples contained 1000, 3000, and 5000 ppm of N,N'-ethylenebisoleamide, respectively. Each sample is placed in a bag below four bags of EVA copolymer (106.6 Kg total) and checked from time to time to determine if it is free flowing. After 15 months, all samples were still free flowing. This behavior is quite remarkable. This is because untreated copolymers are very soft and sticky and will become sticky within a few hours under these conditions. Example 6 EVA bipolymers containing 3000 ppm and 5000 ppm of commercially available antiblocking agents (vinyl acetate content 28%,
A sample with a melting coefficient of 150 g/10 minutes was prepared. Samples containing two commercially available N,N'-ethylenebisoleamides, Adva Wax 240 and Glycolyuve VL, had a smooth texture. Their sticking temperatures were 34-35°C, whereas the EVA copolymer control had sticking temperatures of 30.1-33.5°C. Three commercially available products consisting of N,N'-ethylene bissteamimide, "Advawax" 275, 280 and 290 (Kerstabu),
"Chemamide" W-40 (Fumukoshi Field Co., Ltd.),
"Acrowax" C (Glyco Chemical), oleamide, "Chemamide"U; and two substances of unknown composition:
"Paricin" 285 by B. Ross Co., Ltd. Industries, New York, and "Ross wax" by B. Ross Co., Jersey City, New York, do not have a smooth texture.
Their sticking temperatures were 29-31°C. Example 7 Melting coefficient 43g/10min, vinyl acetate content 33%
EVA bipolymer and EVA bipolymer with a melting coefficient of 400 g/10 min and a vinyl acetate content of 28%, 1000,
Those containing 3,000 and 5,000 ppm of N,N'-ethylenebisoleamide have a smooth feel, and their sticking temperature increases moderately as follows.

[Table] Example 8 Melting coefficient 57g/10min, vinyl acetate content 40%
A commercial batch of EVA copolymer is blended with N,N'-ethylenebisoleamide to produce a formulation containing 4000 ppm oleamide and pelletized.
The N,N'-ethylenebisoleamide migrates to the surface of the pellet and forms a protective coating within a few seconds. These coated pellets are transported without clumping,
and the transfer rate was approximately 20% faster than clay-coated pellets. 6 at 32℃
It remained free-flowing after a week. Clay-coated copolymer pellets were solidified after 30 days under the same conditions. Example 9 Factory-made copolymer containing 90% ethylene and 10% methacrylic acid (melt coefficient 500 g/10 min)
was combined with the following amount of test amide. The composition and adhesion temperature of the samples are shown in the table below. N,N'-ethylenebisoleamide shows a significant increase in stick temperature. Additive (ppm) Sticking temperature, °C Control product 46 5000 Erucamide 43 5000 Stearamide 48 5000 N,N'-ethylenebisstearamide 48 1000 N,N'-ethylenebisoleamide 49 5000 N,N'-ethylenebisoleamide Amide 55 Example 10 The same test was conducted using an ethylene/methacrylic acid copolymer containing 15% methacrylic acid. In this case as well, the sticking temperature of N,N'-ethylenebisoleamide increases significantly, as can be seen from the table below. Additive (ppm) Adhesive temperature (°C) Control product 34 5000 Erucamide 36 5000 Stearamide 42 5000 N,N'- Ethylenebisstearamide 42 1000 N,N'-Ethylenebisoleamide 34 5000 N,N'-Ethylenebis Oleamide 47 Example 11 The same test was carried out on an ethylene/methacrylic acid copolymer containing 15% methacrylic acid and 20% neutralized with Zn ⁺⁺ ions. The melting coefficient of this copolymer is 12 g/10 minutes. In this case as well, N, N′−
The most significant improvement in sticking temperature was obtained with ethylene bisoleamide. The experimental results are shown in the table below. Additive (ppm) Sticking temperature, °C Control product 30 5000 Erucamide 31 5000 Stearamide 40 5000 N,N'-ethylene bisstearamide 41 1000 N,N'-ethylenebisoleamide 40 5000 N,N'-ethylenebisoleamide Amide 48 Example 12 A similar test was conducted on an ethylene/methyl methacrylate copolymer containing 20% methyl methacrylate. Its melting coefficient is 3.2 g/10 minutes. The results are shown in the table below. Additive (ppm) Sticking temperature, °C Control product 53 5000 Erucamide 55 5000 Stearamide 52 5000 N,N'-ethylenebisoleamide 60 Example 13 Ethylene, vinyl acetate (28%) and Similar tests were conducted using a terpolymer of carbon oxide (9%). The results are shown in the table below. Additive (ppm) Sticking temperature, °C Control product 30 5000 Erucamide 30 5000 Stearamide 37 5000 N,N'-Ethylenebisstearamide 30 1000 N,N'-Ethylenebisoleamide 33 3000 N,N'-Ethylenebisoleamide Amide 33 5000 N,N'-Ethylenebisoleamide 33 In this test, N,N'-ethylenebisoleamide did not increase the sticking temperature as much as stearamide, but erucamide or N,N'-ethylenebisstearamide It turns out that it is somewhat more effective. However, it should be remembered that N,N'-ethylenebisoleamide migrates very quickly in this polymer in the migration tests described above. Example 14 Very sticky polymers do not evaluate satisfactorily in the tack temperature test. A tack test was therefore developed to evaluate the effectiveness of anti-blocking agents. A hollow metal cylinder lined with poly(ethylene terephthalate) film with an inner diameter of 7.5 cm and a length of 10 cm is placed on a thin metal plate coated with poly(ethylene terephthalate) film. This cylinder is filled with EVA copolymer pellets, a 2050 g weight is placed on top of the pellets, and a pressure of 4.3 KPa is applied. The filled cylinder is kept at 30±2°C for 8 hours.
Next, carefully remove the pellet column from the cylinder.
If the copolymer maintains a cylindrical shape, it is said to be sticky. When the copolymer pellets collapse into mounds, they are said to be free-flowing. Melt coefficient: 57g/10min, vinyl acetate content: approximately 40%
Mix 1000 and 5000 ppm of the following reagents with EVA copolymer. "Chemamide" S (stearamide) and "Chemamide" E (erucamide) All samples were sticky (resembling wet snow). Samples containing 1000 ppm of additive clumped together in the bag and were not tested for adhesion.
The 5000 ppm sample was tacky in this test. Example 15 The following EVA bipolymer containing the following amides in the following amounts (vinyl acetate content 40%; melting coefficient 57 g/
Samples of 10 min) were made and pelletized as described in Examples 1 and 4 via 10 or 25% amide concentrates.

【table】

[Table] Do*
18 N,N′〓Ethylene bisoleami 500
De*
* Melting coefficient 150g/10 minutes, vinyl acetate content 28
It was made from a 25% concentrate in a 25% EVA copolymerization.
During the preparation of the above-mentioned samples, after making the pellets,
The fluidity of each pellet was immediately measured on a dry screen. The pellets produced in the next experiment were free-flowing. 1, 2, 9, 10, 14, 15, 17 and 18. In the tack test described above in Example 9, the following samples preserved free-flowing properties. 9, 10, 14, 15 and 17. The remaining samples were solidified. Commercial samples of EVA copolymer coated with clay were also collected in this test. Example 16 A sample of the following EVA copolymer (vinyl acetate content 28%, melting coefficient 150 g/10 minutes) was prepared in the same manner as in Example 10.

[Table] The adhesion temperature of the substrate polymer used in experiments 1 to 3 is 30
It was warm at ℃. The adhesion temperatures of the samples in Experiments 1 to 3 are as follows. Experiment Sticking temperature, °C 1 29 2 36 3 34 In this test, oleamide had poor properties, but N,N'-ethylenebisoleamide had good properties.

Claims (1)

[Scope of Claims] 1 (a) a bipolymer of ethylene and vinyl acetate in which the amount of vinyl acetate is about 18 to 55% by weight; (b) the amount of vinyl acetate is about 20 to 40% by weight and monoxide; (c) a terpolymer of ethylene, vinyl acetate and carbon monoxide with a carbon content of about 3% to 12% by weight; (c) a methacrylic acid content of about 6% to 30% by weight and the carboxyl groups in the copolymer are zinc 0 to approx.
from the group consisting of a copolymer of ethylene and methacrylic acid that is 50% neutralized; and (d) a copolymer of ethylene and methyl methacrylate in which the amount of methyl methacrylate is about 18 to 40% by weight. pellets of selected polymers, said pellets containing an additive selected from the group consisting of N,N'-ethylenebisoleamide and N,N'-ethylenebiserucamide in an amount of about 500% by weight of the polymer; A pellet characterized in that it contains an effective amount of ~10,000 ppm to reduce the stickiness of the pellet. 2. The pellets according to claim 1, wherein the polymer is a dipolymer of ethylene and vinyl acetate, or a terpolymer of ethylene, vinyl acetate, and carbon monoxide. 3. The pellet according to claim 2, wherein the additive is N,N'-ethylenebisoleamide. 4. The pellet according to claim 3, wherein the polymer is a dipolymer of ethylene and vinyl acetate. 5. The pellets according to claim 1, wherein the amount of the additive is 1000 to 5000 ppm. 6. The pellet according to claim 5, wherein the amount of the additive is 2000 to 4000 ppm. 7 The polymer also contains about 2-13% by weight of paraffin.
3. A pellet according to claim 2, which contains wax. 8. The pellet according to claim 1, wherein the additive is N,N'-ethylenebisoleamide. 9 (a) a bipolymer of ethylene and vinyl acetate with an amount of vinyl acetate of about 18-55% by weight; (b) an amount of vinyl acetate of about 20-40% by weight and an amount of carbon monoxide of about 3% by weight; ~12% by weight of a terpolymer of ethylene, vinyl acetate, and carbon monoxide; (c) the amount of methacrylic acid is about 6% to 30% by weight, and the carboxyl groups in the copolymer are zinc ions containing 0 to about
a copolymer of ethylene and methacrylic acid that is 50% neutralized; and (d) a copolymer of ethylene and methyl methacrylate in which the amount of methyl methacrylate is about 18% to 40% by weight. In a method for producing pellets with reduced stickiness of a separated polymer, N,
Additives selected from the group consisting of N'-ethylenebisoleamide and N,N'-ethylenebiserucamide in an amount of from about 500 to about 50% by weight of the polymer.
The above method, characterized in that an effective amount of 10000 ppm is incorporated into the polymer before pelletization. 10. The method according to claim 9, wherein the amount of the additive is 1000 to 5000 ppm. 11. The method according to claim 10, wherein the amount of the additive is 2000 to 4000 ppm. 12. Claims in which the polymer is a bipolymer of ethylene and vinyl acetate or a terpolymer of ethylene, vinyl acetate and carbon monoxide, and the additive is N,N'-ethylenebisoleamide. The method described in paragraph 9. 13. The method of claim 12, wherein the polymer also contains about 2-13% by weight paraffin wax.