JPH02222425A - Expandable powdery resin composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a powder resin composition used for powder coating. More specifically, the present invention relates to a foamable powder resin composition that is composed of a polyolefin resin, a foaming agent, and zinc oxide, has adhesiveness to a base material, and exhibits a sound-deadening effect.

[Conventional technology]

Polyolefin resins have excellent moisture resistance, chemical resistance, impact resistance, etc., and are widely used, and are often used in powder coating. Powder coatings are widely used as an alternative to solvent coatings because of their lack of air pollution problems and various other advantages. Conventionally, powder coating has often been used for the purpose of corrosion prevention on metal materials, and the adhesion of the paint used, especially the resin component, to the base material is considered to be an important factor, and various improvements have been made.

For example, JP-A-56-151774 proposes a powder coating composition in which a polyolefin resin and a hydrazine-based high-temperature foaming agent are mixed.

In recent years, the scope of use of powder coating has been increasing more and more, and it is increasingly being applied to parts such as various vehicles and various structures.

When applying powder coating to these shapes, the coating conditions vary, and the powder material composition of the required powder coating is determined depending on the material and shape of the object to be coated, as well as differences in coating temperature and coating equipment. It had to change. However, providing a powder resin composition by changing the composition of the powder material depending on each coating condition is not preferable in terms of the powder manufacturing process.

[Problem to be solved by the invention]

The purpose of the present invention is to obtain a foamable powder resin composition that satisfies a wide range of coating conditions, has a sound-deadening effect, has superior coating film properties after coating, and has good adhesion and coating surface condition. That is.

Nowadays, the materials used for structures such as various vehicles and machinery and equipment range from metals to plastics, and painted objects are being used everywhere, which is unpredictable. For example, spring coils for automobile seats and the like have been desired to have a silencing effect.

[Means to solve the problem]

According to the present invention, 100 parts by weight of polyolefin resin powder, 0.5 to 5 parts by weight of high temperature blowing agent, and 0.1 part by weight of low temperature blowing agent.
A foamable powder resin composition is provided comprising: ~2 parts by weight and 0.5-2 parts by weight of zinc oxide.

The present invention will be explained in more detail below.

The polyolefin resins used in the present invention are mainly polyethylene and polypropylene.

Polyethylene is linear low density polyethylene (LL
) or low density polyethylene (hereinafter referred to as L
It is called DPE. ) is used. These polyolefin resins may be used alone or in a mixture of two or more, preferably LLDPE and LDPE or LLD.
A combination of PB and polypropylene is good.

Further, block or random copolymers of polyethylene and polyolefin can also be used.

Polyethylene, polypropylene and copolymers may be modified. Modification treatment is performed on monobasic unsaturated fatty acids such as acrylic acid and methacrylic acid, unsaturated fatty acids such as dibasic unsaturated fatty acids such as maleic acid and itaconic acid, and acid anhydrides such as maleic anhydride and hymic anhydride. Preferably.

In the present invention, the polyolefin resin is made into powder using an impact crusher such as a swing hammer mill or a turbo mill. The particle size of the powder is usually 100-250 μm. Further, the polyolefin resin may be used by subjecting the pulverized powder to heating and stirring while applying a shearing force. This stirring process removes fibrous whiskers that appear on the pulverized powder, thereby increasing the fluidity of the resin powder.

The high-temperature foaming agent of the present invention is an organic foaming agent conventionally used to obtain foamed materials such as plastics and rubber, which generates gas by decomposition, and whose decomposition temperature for gas generation is approximately 170 to 250. 'C, and a known gas-generating blowing agent such as a hydrazine type blowing agent is used. For example, azodicarbonamide, trihydrazinotriazine, p
-Toluylene sulfonyl semicarbazide, allyl bis(
sulfohydrazine), 4,4'-oxybis(benzenesulfonyl)semicarbazide, and the like. High temperature foaming J
Pl is 0 per 100 parts by weight of polyolefin resin powder.
．． It is 5 to 5 parts by weight, preferably 1 to 4 parts by weight.

If it is less than 0.5 parts by weight, foaming will be insufficient, while if it exceeds 5 parts by weight, it will result in excessive foaming, which is not preferable.

The low-temperature blowing agent used in the present invention is an organic blowing agent similar to the high-temperature blowing agent, and has a decomposition temperature of about 100 to 160°C for gas generation.
It is a known gas-generating blowing agent such as hydrazine type or nitrile type. For example, 4,4"-oxybenzenesulfonylhydrazide, diphenylsulfone-3,3°-disulfohydrazine, N,N'-dimethyl-N,N'-
These include dinitrosoterephthalamide and azobisisobutyronitrile. The low temperature blowing agent is 0.1 to 2 parts by weight, preferably 0 parts by weight, per 100 parts by weight of the polyolefin resin powder.
．． It is 2 to 1 part by weight. If it is less than 0.1 parts by weight, foaming will be insufficient, while if it exceeds 2 parts by weight, it will result in excessive foaming, which is not preferable.

Both the high-temperature type and low-temperature blowing agents of the present invention usually have a
Since it is commercially available as a 20 μm powder, it can be used as is.

Zinc oxide used in the present invention is polyolefin resin powder 1
0.00 parts by weight, 0.5 to 2 parts by weight, preferably 0.00 parts by weight.
1 to 1 part by weight is used. If it is less than 0.5 parts by weight, foaming will be non-uniform, while if it is used in excess of 2 parts by weight, the effect will not change. Zinc oxide is usually commercially available as a powder of about 065 μm and can be used as is.

The foamable powder resin composition of the present invention can be obtained by uniformly mixing the above polyolefin resin powder, high temperature blowing agent, low temperature blowing agent, and zinc oxide at a temperature below the decomposition temperature of the blowing agent. Mixing can be performed using conventional mixing equipment. Preferably, a mixer such as a twin-screw extruder is used.

When the foamable powder resin composition of the present invention is used for powder coating, for example, in a fluidized dipping method, a coating film is formed in the fluidized dipping treatment by preheating and heating after powder application, and at the same time, the foaming agent is decomposed. The coating film and the foam layer are integrated to obtain a coating film including the foam layer. In this case, the preheating temperature, coating time, post-coating heating temperature and time, etc. are determined by the type of polyolefin resin, the type and amount of blowing agent, and the amount of zinc oxide.
It may be selected appropriately depending on the shape of the article to be coated, etc.

In the present invention, the degree of foaming can also be controlled by selecting the heating temperature or heating time after fluidized dip coating.

In addition to the above-mentioned components, the foamable powder resin composition of the present invention may contain additives for improving the physical properties of the resin, such as stabilizers, lubricants, pigments, and antistatic agents.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to this example.

Note that the foaming degree and foaming ratio in the examples were calculated using the following formula.

Example I LDPE (manufactured by Ube Industries, product name: J 3519)
50 parts by weight, LLDPE (manufactured by Ube Industries, product name:
JL1225) 50 parts by weight, zinc oxide (manufactured by Sakai Chemical ■,
1 part by weight of high-temperature blowing agent azodicarbonamide (product name: Ni-go Zinc White) (manufactured by Sankyo Kasei ■, product name: Cellmic C)
2 parts by weight, low-temperature blowing agent 4.4"-oxybisbenzenesulfonyl hydrazide (manufactured by SanIa Kasei ■, trade name: Cellmic S), and carbon black (manufactured by Cabot Corporation, trade name: Palkan 9) A compound was prepared by uniformly mixing 0.8 parts by weight using a Henschel mixer, and the mixture was pulverized to obtain a foamable powder resin composition having an average particle size of 200 μm.

Using the above powdered resin composition, a wire rod with a diameter of 3.2 mm was coated by a fluidized dipping method. Steel wire at 320°C
The powder resin composition was preheated for 225 seconds in a heating furnace, and after being taken out from the heating furnace, it was left to stand for about 10 seconds, and then immersed for 6.5 seconds in a fluidized immersion tank in which the powdered resin composition was fluidized.

After that, put it in the heating furnace again and set it at 170°C.
Heating was performed after dipping for different times: 560, 120, and 195 seconds.

The results are shown in Table 1. In this case, the bubbles in the coating film were uniform throughout the foam layer, and the bubble diameter was approximately 300 IIm.
Met.

Example 2 The procedure of Example 1 was repeated except that 100 parts by weight of the same LDPE was used instead of LDPE and LLDPE. The results are shown in Table 1. In this example as well, the bubbles in the coating film were uniform throughout.

Example 3 Heating temperature 1 after dipping using a rope wire with a diameter of 3.6 mmφ
The same procedure as in Example 1 was conducted except that the heating time was 195 seconds at 70°C. The foaming degree in this case was 50.9% and the foaming ratio was 2.03.

Example 4 Example 3 except that the heating temperature after immersion was 190°C.
I did the same thing. Foaming degree is 54.0%, foaming ratio 2.1
It was 8.

Comparative Example 1 A steel wire rod was subjected to fluid dip coating in the same manner as in Example 1 using the same powdered resin composition as in Example 1 except that zinc oxide was not added. The results are shown in Table 1. In the cell condition of the zero foam layer, the cell diameter of the outer layer was 100 μm.
The bubble diameter in the inner layer was 500 μm and was not uniform.

Comparative Example 2 A steel wire rod was subjected to fluid dip coating in the same manner as in Example 1 using the same powdered resin composition as in Example 1 except that zinc oxide and 4,4'-oxybisbenzenesulfonyl hydrazide were not added. . The results are shown in Table 1. In this case, when the heating temperature after immersion was set to 220°C, the expansion ratio after 195 seconds was about 2.0.

The weight is low and not sufficient. Furthermore, in Comparative Example 2, when the heating time after immersion was increased, the degree of foaming ultimately decreased.

Note that when a sliding coil for an automobile seat was manufactured using the painted steel wire rod obtained in this example, there was no disturbing sound when crimped.

(Hereinafter, blank space) As is clear from the above comparative example, in the case of a powder resin composition that does not contain zinc oxide, a sufficient degree of foaming could not be achieved. is 20
If the temperature is not higher than 0°C, a high expansion ratio cannot be obtained, and depending on the coating conditions, the desired objective may not be achieved. Further, the state of the cells in the foam layer was uniform in the examples of the present invention, but was non-uniform in all of the comparative examples.

Furthermore, it can be seen that as the heating time after immersion increases, the degree of foaming increases in the examples, and it is possible to obtain a desired degree of foaming. On the other hand, in Comparative Example 1, the degree of foaming increases with the heating time after dipping. It is possible to form coatings by powder coating under a wide range of conditions, especially at a wide range of temperatures. Furthermore, the foamable powder resin composition of the present invention has sufficient adhesion, making it possible to obtain a coating film containing an excellent foam layer, and also allowing the degree of foaming of the foam layer of the coating film to be selected, making it suitable for applications that require a sound deadening effect. This can be countered by increasing the degree of foaming.

Claims (1)

[Claims] (1) A foamable powder resin consisting of 100 parts by weight of polyolefin resin powder, 0.5 to 5 parts by weight of a high temperature blowing agent, 0.1 to 2 parts by weight of a low temperature blowing agent, and 0.5 to 2 parts by weight of zinc oxide. Composition.