JPS58187436A - Expanded sheet of styrenic resin, having low polymerization degree, and containing rubberlike material - Google Patents

Abstract

PURPOSE:The titled expanded sheet, prepared by incorporating a polystyrenic resin having a low polymerization degree with a rubberlike material, and having a specific expansion ratio, and improved impact resistance and low raw material cost. CONSTITUTION:An expanded sheet obtained by incorporating 100pts.wt. polystyrenic resin having a low polymerization degree, preferably having 0.6<specific viscosity (etasp)<1.1, <=30X10<4> molecular weight and <=10X10<4> polymerization degree, with 0.5-25pts.wt. rubberlike material, e.g. polystyrenic resin prepared by the copolymerization with styrene or graft polymerization with styrene, hot melting the resultant mixture in an extruder, and extruding the melt through an annular slit at the tip thereof into a cylindrical material. The expansion ratio is 3-20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polystyrene thread resin foam sheet with a new composition, and more specifically, to provide a polystyrene thread resin foam sheet with low raw material cost and excellent impact resistance. It is.

Conventionally, polystyrene resin sheets with a foaming ratio (raw resin density/foamed sheet density) of 3 to 20 times have been widely used, but these polystyrene resin foam sheets have poor mechanical properties because the polystyrene resin is a glassy polymer. In particular, it has poor impact resistance, and is said to be significantly inferior to, for example, other polyolefin resin foams, and is brittle and easily cracked.

Among these, low-polymerization degree polystyrene resin has the advantage of being relatively cheaper to manufacture than high-polymerization degree polystyrene resin, but because of its low degree of polymerization, its impact resistance further decreases, and foamed sheets made of this resin are The resin is extremely brittle and cannot fully function as a foam sheet, and for this reason, the resin is considered unusable.

Concerning Song Dynasty's solutions to this problem were: (1) manufacturing a foam sheet by mixing high polymerization degree polystyrene resin (η, 31. is about 1.3 to 1.6); (2) reducing the thickness of the foam sheet; (2) Producing the foam sheet by increasing the number of cells.

However, with these methods, no significant reforming effect can be expected, and method (2) increases the manufacturing cost, and methods (2) and (2) require a molder (which performs the molding process of the foam sheet).
(heating a foam sheet to soften it and molding it with a mold) does not necessarily meet the needs of the molded product, for example, the thickness of the molded product becomes thinner, the thermal conductivity of the foam sheet is low, and the heating efficiency deteriorates. , or it becomes difficult to form deep marks.
There are major drawbacks such as, and no fundamental solution has been found yet.

In view of the current situation, the present invention was conceived and as a result of intensive research, it was discovered that by incorporating a rubber-like substance into a low polymerization degree polystyrene resin, its impact resistance was significantly improved and it could withstand practical use for 1 minute. , which overcomes the drawbacks of polystyrene resin foam sheets as described above.

That is, the present invention is a polystyrene resin foam sheet containing a low-polymerization degree polystyrene resin V-shaped material, which can be manufactured using inexpensive polystyrene resin, so the manufacturing cost is low and the quality is durable. This invention is characterized by providing a polystyrene resin foam sheet with improved impact resistance.

The polystyrene resin foam sheet of the present invention is usually manufactured by heating and melting a raw material resin and a low-boiling organic compound as a foaming agent in an extruder, and extruding it into a cylindrical body through an annular slit at the tip of the extruder. The agent may be press-fitted into an extruder, or it may be impregnated into polystyrene resin in advance and used as a foamable polystyrene resin.

In the present invention, when the rubber-like substance increases, the impact resistance Pig increases in the direction of 1-2, but the bending elasticity decreases. In order to expect - to be constant, it is necessary to make the skin layer of the foam sheet more dense by cooling it with air blowing or the like immediately after extruding it.However, At the same time, the density of the inner layer must be lowered and the foaming ratio of the entire foamed notebook manufactured must be adjusted to be equal after MiJ of areal density layer formation.However, in general, the outer layer should be made with a higher areal density. However, the polystyrene resin foam sheet of the present invention has excellent results in these respects. (6) I can do something.

In the present invention, the low polymerization degree polystyrene resin refers to a specific viscosity η, :l nail resin 1g'toluene 100m/, 30"C
) is 11 or more i-1 molecule-t (Mw) 80 ×l
O' or more 1., degree of polymerization is 4r, ) 1'O'x 10
4 or more, especially η1. It is preferable that l is smaller than 0.6 and smaller than 1.1. 1. In the invention, the ``cono''-like substance includes 1li-1'
;; (synthetic comb component or polystyrene resin graft-polymerized with styrene), 5F31, L41. ．． 3H
Synthetic rubbers and natural rubbers such as , buna rubber, CI (butyl rubber), and elastomers such as ethylene-vinyl acetate copolymer are included. Although it exists in a blended state, it is 11J in terms of impact resistance modification effect.
The condition of the person is excellent.

Therefore, r(i-, PS, S L31i) are particularly suitable.

In addition, if the rubber-like substance exceeds 25 parts by weight, the low ↑゛ of the bending elasticity of ``-1'' becomes even more significant, which also increases the cost of the material *1. Therefore, cost benefits and impact resistance can be achieved at the same time. To satisfy the requirements, the content of rubbery substances should be approximately 0.
5 to about 30 double parts are preferred.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these examples and can be appropriately modified within the scope of the present invention.

Example 1-1 A press-in part for a low-boiling organic compound using a raw material resin blended with a nucleating agent as a blowing agent is provided (l,/l) 22
Heat and melt at 220°C together with the blowing agent press-injected in the extruder in step 5, and 11. [)=a It was cooled to 150° C. using an O extruder and extruded through an annular slit at the tip thereof to produce a polystyrene thread resin foam sheet.

11, i-Ki-1 resin, 100 parts by weight of low polymerization degree polystyrene resin (η: 31.'l 019) as adhesive resin,
I)-1 Bow resin (polystyrene resin in which the rubber component type 8 is polymerized with styrene, which is a sticky resin) 5
Merck 1.3 heavy duty part was evenly blended as nucleating Ml [2].
! The lf portion is press-fitted, extruded through the annular slit, and immediately cooled in air to form a high-density layer on the skin layer of the foam sheet to a thickness of 2. ], ms, sea 1-11'
+ 1-049. Polystyrene thread resin constant foam sheets such as heavy paper 200 f, yn were manufactured continuously.

Example 1-2 Using the same raw material resin as in Example h1411-1, Example 1
A foamed sheet was manufactured by the same operation as in -1. I11
The difference from Example 1-1 is that the epidermal layer is more dense.

Example 1-3 Same low polymerization degree polystyrene resin as Example 1-1 and t
(i, -Pε) Using 100 and 10 tons of the resin as the raw material resin, foamed sheets were produced in the same manner as in Example 1-1.

Example 1-4 Low polymerization degree polystyrene resin same as Example 1-1 and 1
(A foamed sheet was manufactured by carrying out the same operation as in Example 1-1 using 100 parts of 1''S resin and 111 parts of 5-weight resin as the raw material resin.

Comparative Example 1 Example 1. Same as -1=-low polymerization degree polystyrene 100
A foamed sheet was manufactured by performing the same operation as in Example 1-1, using only parts by weight as the raw material resin.

Comparative Example 2 Highly polymerized polystyrene resin (ηsp 1.6) 10
A foamed sheet was produced by carrying out the same operation as in Example 1-1, except that only the round part of the 0 ton was made of 11 resin.

Example 2 Raw resin pelleted with nucleating agent, /”D = 3
The mixture was melted by heating at 200° C. in an extruder No. 9, and extruded through an annular slit at 150° C. at the tip thereof to produce a polystyrene thread resin foam sheet.

Low polymerization degree polystyrene resin impregnated with 11-butan 7% foaming agent (polystyrene resin content η, -0,9) l O'0 parts by weight 1, p
1l)-1's resin 5o! same as Example 1-1! Ti part, evenly shake Merck 1.8 heavy duty part as a nucleating agent.

! - Then, the mixture was put into the popper of an extruder, melted in a heating bath, extruded through annular Surin 1-1, and the same operation as in Example 1-1 was carried out to produce a foamed sheet.

Example 3 Polystyrene resin lo same as Example t-t.

An extrusion sheet was produced by carrying out the same operation as in Example 1-1 using 11 liters of plastic and 9 parts by weight of a synthetic comb (4 parts of N) as the raw resin.

Example 4 Polystyrene resin lo same as Example 1-1.

Using 30 parts by weight of the same synthetic rubber as in Example 3 as a raw material resin, a foamed sheet was produced in the same manner as in Example 1-1.

Table 1 shows the results of quality evaluation of the polystyrene thread resin foam sheets obtained in each Example and Comparative Example.

*1) ((T)l: Inexpensive, ○: Slightly inexpensive, △: Slightly expensive, ×: Expensive *2) The larger the value, the higher the density. Judging from the shape of the bubbles *3) The higher the number, the more impact resistant it is. Determined by falling ball test *4) The higher the number, the higher the bending strength. Judging by the repulsive force when a certain strain is generated *5) Molding into food packaging trays *6) Applicability to deep drawing molding, judged by the shape of the tray ◎: Good, 0: Fairly good, △: Slightly poor, ×: Poor In Table 1, Examples 1-1 to 1-4.2.3 and 4
Comparing Comparative Examples 1 and 2, it is found that the impact resistance modification effect of the rubber-like substance on the polystyrene thread resin foam sheet is remarkable, and the molding processability is reduced by making the skin layer higher density. It is recognized that the bending strength can also be maintained without any stress. Further, by comparing Examples 1-2 and 2, it can be confirmed that the manufacturing method is not involved.

Regarding the state of the rubbery substance, by comparing Examples 2 and 3, it can be seen that copolymerization or craft polymerization with sunalene is preferable to blending with polystyrene resin. Therefore, considering the cost merit in addition to F2, it can be seen that it is preferable to use 1N-1'+; resin.

As shown in Section 4, the present invention not only reduces manufacturing costs but also significantly improves moldability in addition to impact resistance.
- To provide a novel low polymerization degree polystyrene thread resin foam sheet.

Claims (1)

[Scope of Claims] 1. A low polymerization degree polystyrene resin sheet which is made by blending a rubbery substance with a low polymerization degree polystyrene thread resin and has an expansion ratio of 8 to 20 times. 2. A foamed sheet according to claim 1, comprising 0.5 to 25 parts by weight of a rubber-like substance mixed with 100 parts by weight of a low polymerization degree polystyrene resin. 3. The specific viscosity of the low polymerization degree polystyrene resin component is 06〈η
8[,・(1,1) Claim 1 or 2
Foam sheet as described in section. 4. The foamed sheet according to claim 1 or 2, wherein the rubbery substance is copolymerized or kraft polymerized with styrene.