JPS6115094B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel olefin-based thermoplastic resin composition, and more particularly to an olefin-based thermoplastic resin composition with improved salt water resistance and adhesion to metals. BACKGROUND ART Conventionally, in order to protect metal surfaces such as steel pipes and steel plates from corrosion, methods have been used to coat the metal surfaces with an olefinic thermoplastic resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or the like. However, such olefin-based thermoplastic resins alone cannot adhere to metal surfaces;
Furthermore, even if a tackifier is added to improve the adhesion, the reality is that it is almost impossible to obtain a coating that adheres to an extent suitable for practical use. Various attempts have been made to improve this drawback; for example, a method is known in which a primer having affinity for both the metal and the thermoplastic resin is applied between the metal and polyolefin. However, primer treatment has the drawback of reducing productivity and increasing product prices since it requires additional steps. As a result of intensive studies to improve this conventional technology, the present inventors have developed a thermoplastic resin that exhibits extremely excellent properties by blending butadiene rubber with an aliphatic tackifier into an olefin thermoplastic resin. The present inventors have discovered that a composition can be obtained, and have completed the present invention. That is, an object of the present invention is to provide a novel composition that exhibits excellent adhesion to metals and exhibits excellent salt water resistance when laminated to metals. This is achieved by blending 5 to 40 parts by weight of an aliphatic tackifier and 20 to 60 parts by weight of butadiene rubber to 100 parts by weight of the plastic resin. The olefinic thermoplastic resin used in the present invention includes ethylene, propylene, 1-butene,
4-methyl-1-pentene, 1-hexene, 1
- Homopolymers of 1-olefins usually having 2 to 10 carbon atoms, such as octene, 1-decene, etc., or containing such 1-olefins as the main component, such as vinyl acetate, vinyl propionate, acrylic acid, methacrylic acid, 1,3 - A copolymer containing other comonomers copolymerizable with 1-olefin such as butadiene, isoprene, etc. Specific examples include polyethylene, polypropylene, ethylene-vinyl acetate copolymer, poly-1-olefin, etc. -butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-butadiene copolymer, and the like. Such olefinic thermoplastic resins may be crystalline or amorphous, but those with a melt index at 190°C in the range of 0.1 to 400 g/10 minutes, more preferably 1 to 150 g/10 minutes. is preferable; if the melt index value is small, processability will be difficult, and if it is too large, the strength of the film will decrease, which is not preferable. In particular, polyethylene-based thermoplastic resins, such as polyethylene, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, etc., are used in the present invention, but ethylene-vinyl acetate copolymers, especially vinyl acetate, are preferred in the present invention. Copolymer contents of 3 to 15% by weight give excellent results. The aliphatic tackifier used as the second component in the present invention has as its main component any component contained in the _C4 to _C6 fraction, and if necessary, other comonomers. In addition, it is a tackifier obtained by cationic polymerization according to a conventional method, or a tackifier obtained by modifying a tackifier according to a conventional method. Examples of modification methods include hydrogenation, air oxidation, and addition reaction of unsaturated carboxyl compounds such as maleic anhydride.
Any modified resin that exhibits essentially the same effect as a partially modified tackifier is included in the aliphatic tackifier of the present invention. Such tackifiers usually have a softening point
It has a temperature of 60 to 140°C, and those with a temperature of 80 to 120°C are particularly prized. The butadiene rubber used as the third component is a butadiene homopolymer or a copolymer mainly composed of butadiene, and specifically, polybutadiene, styrene-butadiene random copolymer, styrene-butadiene block copolymer, etc. Examples include polymers. Such butadiene rubber usually has a number average molecular weight of 50,000 to 1,000,000, preferably 100,000 to 1,000,000.
500,000 and is in a fixed state at room temperature.If the molecular weight is small, the stickiness of the compound will be large, and if the molecular weight is large, the processability of the compound will be difficult.
Among butadiene rubbers, polybutadiene obtained by solution polymerization, particularly cis-1,4 polybutadiene, is preferred. The blending ratio of the three components constituting the composition of the present invention is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, of the aliphatic tackifier and 20 parts by weight of the butadiene rubber to 100 parts by weight of the olefinic thermoplastic resin. -60 parts by weight, preferably 30-50 parts by weight. At this time, if the amount of the aliphatic tackifier is too small, the adhesion to the metal will be poor, and if it is too large, the mechanical strength of the compound will be reduced. Furthermore, if the amount of butadiene rubber is too small, the salt water resistance will be poor, and if it is too large, the mechanical strength of the compound will be reduced, as in the case of aliphatic tackifiers. In the present invention, a blend is obtained by kneading the above three components according to a conventional method such as a Henschel mixer, a Banbury mixer, a roll, an extruder, etc. At this time, if necessary, a heat stabilizer,
Other commonly used ingredients such as lubricants, fillers, pigments, etc. may also be added. The composition of the present invention thus obtained can be used to prevent rust of metal materials used in fields where corrosion resistance is required, such as anti-corrosion coating of steel pipes for water and sewage, and anti-corrosion coating of metal materials immersed in seawater. It is suitable for coating, and after coating a metal material with the composition of the present invention, it is
A coating with good adhesion and salt water resistance can be obtained by heat treatment for 180 minutes, preferably 10 to 80 minutes. The present invention will be illustrated in more detail with reference to Examples below, but the scope of the present invention is not limited thereby. Example 1 Ethylene-vinyl acetate copolymer, aliphatic tackifier and polybutadiene rubber were kneaded in a Brabender at 130°C for 20 minutes in the proportions shown in Table 1, and then pressed at 130-150°C in a press molding machine. Pressure 10Kg/
A film with a thickness of 1 mm that was press-formed for 2 minutes under conditions of ² cm2 was placed on a well-degreased bright cold-rolled steel plate (JISG-3141) with a thickness of 1 mm, and heat-treated at 150℃ for 60 minutes in the presence of air. By doing this, a laminated sheet consisting of the composition and steel plate was created. This laminated sheet was tested for adhesion and salt water resistance using the following method, and the results are shown in Table 1. 1 Adhesion Test Using an Erichsen tester, a sample was extruded with a punch at a constant speed of 0.1 mm per second, and the distance was expressed as the distance at which cracking and peeling occurred. 2 Salt Water Resistance Test A sample was cross-cut with a razor and exposed in a salt water spray tester for 50 hours.The sample was thoroughly washed with water and its rust state was observed. ×: Rust occurs on the entire surface. Δ: Slight rusting occurred. ○: Some rust occurred. ◎: No rust occurs at all.

[Table] From the results, the compositions in which ethylene-vinyl acetate copolymer was blended with an aliphatic tackifier and polybutadiene rubber, ethylene-vinyl acetate copolymer alone (experiment number 5), ethylene-vinyl acetate copolymer It can be seen that both adhesion and salt water resistance are superior to the two-component systems of polymer and polybutadiene rubber (Experiment No. 4) or ethylene-vinyl acetate copolymer and modified aliphatic tackifier (Experiment No. 3). Example 2 Physical properties were evaluated in the same manner as in Example 1 except that polyethylene was used in place of the ethylene-vinyl acetate copolymer and butadiene-styrene copolymer was used in place of the polybutadiene rubber. The results are shown in Table 2.

【table】

[Table] From this result, it can be seen that even when polyethylene is used, the performance is almost the same as when ethylene and vinyl acetate copolymer is used (Experiment No. 2). Also, when butadiene-styrene rubber was used instead of butadiene rubber (experiment number 7)
It can be seen that it also has excellent adhesion and salt water resistance. Example 3 A test was conducted according to Example 1 except that the amount of heat-modified aliphatic tackifier was changed, and the performance was evaluated. The results are shown in Table 3. The strength of the composition was determined by performing a tensile test on the strength of the press film mixed with a Brabender using an Instron type tensile tester, and rated as ○ for practical use, △ for slightly inferior, and × for impractical. It was displayed in

[Table] From the results, it can be seen that when the amount of acid-modified aliphatic tackifier increases (experiment number 14), adhesion and salt water resistance can be obtained, but the strength decreases and is not practical. On the other hand, if no aliphatic tackifier is used (Experiment No. 4), the strength of the composition is sufficient, but the adhesion and salt water resistance are poor, making it impractical. Example 4 A test was conducted according to Example 1 except that the amount of polybutadiene was changed, and the performance was evaluated. The results are shown in Table 4.

[Table] From the results, it can be seen that when the amount of polybutadiene rubber is increased (Experiment No. 17), the adhesion and salt water resistance are sufficient, but the strength of the composition decreases, making it impractical. Conversely, if it is not used (Experiment No. 3), the strength of the composition is sufficient, but the adhesion and salt water resistance are poor and it is not practical.

Claims (1)

[Claims] 1 (A) 100 parts by weight of olefinic thermoplastic resin, (B)
A novel olefinic thermoplastic resin composition comprising 5 to 40 parts by weight of an aliphatic tackifier and 20 to 60 parts by weight of (C) a butadiene rubber. 2. The composition according to claim 1, wherein the olefin thermoplastic resin has a melt index of 0.1 to 400 at 190°C. 3. The composition according to claim 2, wherein the olefinic thermoplastic resin is a polyethylene resin. 4. The composition according to claim 3, wherein the polyethylene resin is polyethylene or an ethylene-vinyl acetate copolymer. 5. The composition according to claim 1, wherein the aliphatic tackifier is a resin having a softening point of 60 to 140°C. 6. The composition according to claim 1, wherein the butadiene rubber is polybutadiene or a styrene-butadiene random copolymer.