JPS60114140A - Float - 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 The present invention relates to a float with improved water absorption resistance and pressure resistance suitable for use in the deep sea, and expandable thermoplastic resin particles used therein.

The float according to the present invention is used, for example, by being attached in a cylindrical or spherical shape to one side of a fishing net that frames the outer ring of the fishing net. It is especially intended for use in the deep sea,
When a float is used underwater, the first quality requirements are that it has high buoyancy and does not absorb seawater.

Due to the water pressure that conventional floats receive when used underwater,
There was a drawback that water was absorbed into the float, resulting in a decrease in buoyancy.

In order to compensate for this drawback, measures can be taken such as lowering the foaming ratio of the entire float, lowering the foaming ratio of only the surface layer of the float to form a skin layer, or applying a water-resistant substance such as lacquer to the float's surface. However, since these treatments involve a molding process and a post-process, they have the drawback of increasing the number of processes and increasing costs, and they also do not have sufficient water absorption resistance. Furthermore, at present, the resin particles themselves used for molding have not yet been modified to prevent water absorption.

As a result of intensive research into the above-mentioned current situation, the inventors of this invention discovered a float that exhibits its original characteristics for a long period of time in the deep sea under high pressure by using specific expandable thermoplastic resin particles. Ta.

Thus, according to the present invention, i) a copolymer composed of an aromatic vinyl monomer and a polyfunctional monomer copolymerizable with the aromatic vinyl monomer and having a gel content of 80% by weight or more;
) A float with improved water absorption resistance and pressure resistance is provided, which is formed by molding expandable thermoplastic resin particles comprising a blowing agent which is an easily volatile substance having a boiling point lower than the softening point of the copolymer. .

In the expandable thermoplastic resin particles used as the material for the float of this invention, the product obtained by copolymerization must have a gel content of 80% or more, and a copolymer having such a gel content is required. can be obtained by copolymerizing the above-mentioned aromatic vinyl monomer using a small amount of a polyfunctional compound according to a conventional method.

Copolymerization methods include, for example, the suspension method in which a suspending agent is added to the monomers and the suspension is stirred to effect crosslinking, or the monomers are dispersed in water containing a surfactant and crosslinked while being stirred. There are various emulsification methods.

In this specification, the glu content of the copolymer means
This is the amount of M remaining as a glue component under the conditions of 8-hour immersion in toluene at .degree. C., and the specific measurement method will be described later.

The gel content in the resin particles of this invention is generally 80
-95% by weight, preferably 60-80% by weight.
If the gel content is less than 80% by weight, the water absorption resistance will not be improved, and if it exceeds 95% by weight, the foaming property will be poor.

The aromatic vinyl monomer used in this invention is c.
Examples include styrenic monomers such as styrene, α-methylstyrene, and vinyltoluene.

Examples of the copolymerizable polyfunctional monomer include divinylbenzene, polyethylene glycol dimethacrylate, triadyl cyanurate, and diacylph. Usually, the polyfunctional monomer is used in an amount of about 100 parts per 100 parts of the aromatic vinyl monomer. 0. O1
~0.5 part is added, but the amount of the polyfunctional monomer added varies depending on the type of the polyfunctional monomer and the type of polymerization initiator described later. Generally, by adding this amount, the cyclo content becomes 80% by weight or more, and crosslinking is carried out.

Furthermore, in order to modify this copolymer, other vinyl monomers such as methyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, etc. may be mixed and copolymerized within 10 parts. You can also do it.

Suitable easily volatile substances include organic compounds whose boiling point is below the softening point of the copolymer and which are gaseous or liquid at normal pressure, such as gas, propane, butane, pentane, hexane,
Hydrocarbons such as cyclopentane and cyclohexane; norogenated hydrocarbons such as methylene chloride, dichlorofluoromethane, chlorotrifluoromethane, and trichlorofluoromethane are used as blowing agents. These blowing agents may be used alone or in combination of two or more.

In addition, known polymerization initiators such as benzoyl peroxide can be used, and even if a solvent is included to promote the penetration of the blowing agent into the resin when producing expandable thermoplastic resin particles, it is possible to No problem. Suitable examples of such a solvent include aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated ethylenes such as dichloroethylene, trichlorethylene, and tetrachlorethylene.

To manufacture the float of the present invention, it is sufficient to follow a conventional method. For example, expandable thermoplastic resin particles are pre-foamed in advance, and the pre-expanded particles are placed in a mold for molding with small holes etc. A molded article having a hole through the hole can be obtained by filling the cavity and heating the pre-expanded particles to a temperature above the softening point with pressurized steam to fuse and integrate each pre-expanded particle.

The shape of the float of this invention is not particularly limited, and a specific shape is cylindrical as shown in FIG. 1.
Floats are usually colored in dark green, dark yellow, brown, etc. (In the figure, a is 508 N1
85m%b is 20g~5011rI11C has a pore diameter of 5fl
-IQW are shown respectively. ) The foaming ratio of the float of this invention is selected depending on the water depth in which it will be used, specifically 5.0 to 6.0 times at 150 m and 8.0 times at 500 m.
~8.5 times, 2.0 to 2.5 times at 1000m, 100
At 0 m or more, it is 2.0 times or less. In addition, when only styrene polymer is used without using a polyfunctional monomer, it is 8.0 to 4.0 times faster at 150 m, and 2.0 times faster at 500 m.
~2.6 times, and cannot be used at a distance of 1,000 m or more.This invention has been improved in these respects, and also has the advantage that it can be used as is because it does not require the formation of a skin layer or hydrophobic coating. have.

The present invention will be explained in detail below using examples.

Example 1 2,400 g of pure water and 9.62 g of magnesium birophosphate and 0.299 g of sodium dodecylbenzenesulfonate as suspending agents were added to a reactor with an internal volume of 5.61 and equipped with a stirrer, and then the diameter of the particles was 0.58 g. +u+~0.71+ff1l
Styrene polymer particles 480f having a range of Kl were suspended.

Separately, benzoyl peroxide 6,929 and divinylbenzene 4.8y (manufactured by Sankyo Kasei, purity 55%) were added to 192%
It was dissolved in 0r styrene monomer to form a monomer solution, and while the temperature inside the container was maintained at 85° C., the solution was continuously added dropwise under the conditions shown below to proceed with polymerization.

From the start of dropping to 2 hours 917012 hours per hour ~
Up to 4 hours l / 82014 hours - up to 6 hours l
/ 47 (At 5 hours and 80 minutes after the start of one drop, butane 962 was added as a blowing agent over 15 minutes. Furthermore, at 6 hours and 80 minutes after the start of dropping, the temperature was started to increase and the temperature was maintained at 120°C for another 6 hours. After ff1 polymerization and impregnation, the mixture was cooled to 80° C. to obtain expandable polystyrene particles.

After aging the expandable polystyrene particles for 4 days in a cold place, they were pre-foamed to an expansion ratio of 2.5 times. 20～
After 24 hours, fill the mold with the Nobi foam particles.
1. The molded product was heated with steam at 0 kg/m (gauge pressure) for 60 seconds, cooled with water for 2 minutes, and the fused molded product was taken out from the mold. The shape of this molded product is 92M long and 15W wide!
I1. A square rod with a thickness of 15 mm was used, and each foamed particle was well fused to each other from the surface to the inside.

ffl, in which the molded product was aged in the air at room temperature for 24 hours.

The weight of the molded product was measured, and the molded product was immediately completely immersed in water under a pressure of 70 kg/m (gauge pressure) and held in that state for 60 hours. After 60 hours of nailing, the molded product was taken out and immediately First, the weight M: (B) of the molded article was measured.

The absorption rate of the molded article immersed in water for 60 hours under a pressure of 0 kg/cJ was 1.9% by weight.

First, the gel content of the expandable polystyrene copolymer is 50
Put the above copolymer 52 that does not contain a blowing agent and 25 o2 of toluene into a 0 cc Erlenmeyer flask, attach a cooling pipe to the Erlenmeyer flask, and keep it at 60"C in a hot water bath for 8 hours. After cooling to room temperature, transfer to an 8 O mesh wire mesh. The gel content and the sol content were separated, the gel content was dried at 90°C for 6 hours, and after cooling to room temperature, the weight of the gel content was measured, and the yoshital content was measured using the following formula: The foaming property The gel content of the polystyrene particles was 72.0% by weight.

Examples 2 to 5 and Comparative Example 1 The same procedure as in Example 1 was performed, except that the type and amount of the polyfunctional monomer was changed. The results are shown in the first section along with Example 1.
Shown in the table.

Examples 6 to 1O and Comparative Example 2% 8 Pure water 2400 ~ in a reactor with a stirrer with a content of 5.67? and a? Shu Qi 1] as magnesium pyrophosphate 9.6y,
0.29 F of sodium dodecylbenzenesulfonate was added, and benzoyl peroxide 6, Of and a polyfunctional monomer dissolved in styrene monomer 240 (1) were added. While stirring the suspension, The temperature inside the container is 90
℃ and maintained for 6 hours to advance polymerization.

Next, add 96f of butane and start raising the temperature to 120f.
After polymerization and impregnation for a further 6 hours at a temperature of 8°C
The mixture was cooled to 0° C. to obtain expandable polystyrene particles.

Particles with a diameter in the range of 0.98 mm to 1.17 mm were sieved out from the particles, aged in a cold place for 4 days, pre-foamed to a foaming ratio of 2.5 times, and after 20 to 24 hours, they were passed through a steam molding machine. Molding was carried out under certain conditions. The molded product size is length g2Mm, width 1flπ, and thickness 15ff. Water absorption and gel content were measured using the same procedure as in Example 1 to evaluate quality.

The results obtained by changing the type and amount of the polyfunctional monomer used are shown in Table 2 together with Comparative Example 2.8.

Table 2 The water absorption of the expandable polystyrene particles of Example 1 and Comparative Example 10 was measured under the conditions of varying the pressurized water pressure and the expansion ratio and soaking them for 60 hours. The results are shown in FIG. In the figure, the vertical axis is the water absorption rate (A), the horizontal axis is the foaming ratio, and the alphabet is the pressurized water pressure (kg/dxa and at: 50kg/cd,
b and b': 70 kg/all, C: 1
00 kg/m), the solid line shows the one of the present invention obtained in Example 1, and the broken line shows the conventional one obtained in Comparative Example 1.

As is clear from the above results, if the glue content is less than 80% by weight, no effect of preventing water absorption in the molded article can be expected. In addition, even if the gel content is increased to 80%, the water absorption rate will not decrease to 1.8%, so it is not economically advisable to add more polyfunctional monomers than this. I can not say.

From the above, it can be seen that in order to obtain the effect of preventing water absorption, the gel content is 80% by weight or more, preferably 60 to 80% by weight.

Furthermore, as is clear from Figure 82, when a conventional product with a foaming ratio of 262 times is subjected to pressurized water pressure of 70 kg/cd for 60 hours, the
~5% water absorption is observed. This means that it is not possible to measure the increase in buoyancy by increasing the foaming ratio, so 70kg/(
! Although it is impossible to use the product under pressure water pressure (water depth > room), the water absorption rate of this product under such conditions is 1.
The water absorption rate is 4~4. The foaming ratio when reaching 5% is 8.0 times. In other words, since the expansion ratio can be increased from 2.2 times to 8.0 times, the buoyancy of the float can be improved by as much as 22%. In addition, this product
Even in the deep sea of 7,007 f'J or more, it has sufficient buoyancy, absorbs little water, and can be used for practical purposes.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a specific example of the float of the present invention. Figure 2 shows the results when using the present invention and the conventional float.
It is a graph which shows an example of a foaming ratio-water absorption characteristic diagram.

Claims (1)

[Claims] 1.1) A copolymer composed of an aromatic vinyl monomer and a polyfunctional monomer copolymerizable with the same and having a gel content of 80% by weight or more, and 11) The copolymer 1. A float with improved water absorption resistance and pressure resistance, which is formed by molding expandable thermoplastic resin particles and a foaming agent which is an easily volatile substance having a boiling point lower than the softening point of .