JPS608329A - Manufacture of poly-4-methyl-1-pentene foam, and foam produced thereby - Google Patents

Abstract

PURPOSE:To obtain the titled semirigid or soft foam having high heat-resistance and useful as a high-temperature heat-insulation material, etc., by carrying out the foaming of the resin under compression at a restricted temperature using a specific foaming agent. CONSTITUTION:(A) poly-4-methyl-1-pentene (preferably having a melt-flow rate of 0.1-30g/10min under the load of 5kg at 260 deg.C and a melting point of <=235 deg.C) is mixed with (B) a foaming agent having a decomposition initiation temperature of higher than the softening point of the component A (e.g. azodicarbonamide), and the mixture is filled in a mold which can be subjected to the compression, heating and cooling, and pressed while keeping the temperature of the mold below the decomposition point of the foaming agent. The mold is heated above the melting point of the component A to decompose the foaming agent, cooled and opened when the mold temperature reaches (the crystallization temperature of the component A)+ or -10 deg.C, or the mold is cooled to a temperature lower than the crystallization temperature by >=10 deg.C, heated again, and opened when the mold temperature reaches (the melting point of the component A)-20 deg.C-(the melting point) to effect the foaming of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing poly4-methyl-1-pentene foam.

Foams such as polyethylene, polystyrene, and polypropylene are heat-insulating, cold-insulating, and soundproofing materials.

It is widely used as a cushioning material in construction materials, automobile parts, and packaging materials. In addition, these foams can be produced by impregnating polyethylene with an evaporative foaming agent and extruding it into foam, or by kneading the decomposed foaming agent, polyethylene, etc., and if necessary, a crosslinking agent under normal pressure or pressure. A method of foaming after heating is known.

However, these polyethylene, borisdylene, and polypropylene foams have a low softening temperature and cannot be applied to fields where heat resistance is required. On the other hand, poly-4-methyl-1-pentene (hereinafter sometimes abbreviated as TPX) is known to be a resin with a high melting point and excellent heat resistance, although it is in the same category as polyolefin. However, since the melting point of TPX is higher than the decomposition start temperature of commonly used decomposable blowing agents such as azodicarbonamide and azobisisobutyronitrile, conventional foaming methods require a step of melt-kneading TPX and the blowing agent. Since the foaming agent decomposes before the TPX melts and the generated gas escapes, a good foam cannot be obtained. Furthermore, even if a blowing agent could be contained under pressure, the viscoelasticity (melt tension) of TPX rapidly decreases above the melting point, so even if you try to foam the TPX melt, the gas escapes quickly and does not work well. Foam cannot be obtained. Possible methods to improve these drawbacks include using a decomposition blowing agent with a decomposition temperature higher than the melting point of TPX and crosslinking to further improve the melt tension, but the former method is currently not available. Even commercially available high-temperature foaming agents are at most close to the melting point N of TPX, and the decomposition is not sharp, and gas begins to be generated substantially below the melting point of TPX, so conventional foaming methods cannot produce satisfactory results. Even in the latter case, unlike polyethylene, TPX is different from polyethylene, and even if you try to crosslink it with a commonly used crosslinking agent such as peroxide, the molecular chain scission reaction is faster and the melt tension decreases, so there is no solution. was the current situation. In the past, the specific volume of TPX foam, especially foam, was 3.5Crn.
'/g or higher was not known at all.

The present inventors have found that a good 'I'PX ia
As a result of conducting various cross-sections to develop methods for producing TPX foam, we discovered that a good TPX foam can be obtained by using a foaming agent with a specific decomposition start temperature and by regulating the heating temperature under compression. The present invention has now been completed.

That is, the present invention provides poly4-methyl-1-pentene (A
) and a blowing agent (B) having a decomposition start temperature exceeding the softening temperature of poly-4-methyl-1-pentene (/1) are mixed and placed in a mold that can be compressed, heated and cooled at a molding temperature. After filling the blowing agent (B) by keeping it at a temperature below the decomposition start temperature, the inside of the mold is compressed, and then the blowing agent (B) is heated to a temperature above the melting point of the poly-4-methyl-1-pentene (A). After decomposition, it is cooled and the temperature of the mold becomes the same as the poly-4-methyl-1-
When the crystallization temperature of pentene (A) reaches ±10°C, it is released, or the poly-4-methyl-1-pentene (A)
) is cooled to a temperature at least 1[ ]"C lower than the crystallization temperature of the poly(4-methyl-1-pentene), and then heated again until the temperature of the mold is between the melting point of poly4-methyl-1-pentene (10 - 20"C and the melting point of A method for producing a poly-4-methyl-1-pentene foam, which is characterized by foaming by opening the foam when the foam reaches a certain range, and a poly-4-methyl-1-pentene foam having a specific volume of 3.5 Off3/g or more. It provides the body.

Poly-4-methyl-1-pentene (
A) is a homopolymer of 4-methyl-1-pentene or 4-methyl-1-pentene and usually 20 mol% or less of other α-olefins, such as ethylene, propylene, 1-
Butene, 1-hexene, 1-octene, 1-decene, 1
- Tetradecene, 1-octadecene, etc. without 2 carbon atoms)
It is a crystalline copolymer with 20 α-olefins. Poly 4-methyl-1-pentene (A) is usually melt flow rate) (raFR: load 5 kQ, temperature 26
0”C) Force 30.1 to 50g/10min,
Preferably, it is in the range of 0.1 l/X, 50 g, 710 min, preferably G machining l, a force i2, 55'' C or less, or foam moldable.

Poly 4-methyl-1-pen 5-one (At
These are the values measured by the softening temperature, melting point, and crystallization temperature of

Softening temperature: ASTM. All Vicat softening points were measured in accordance with D1525, and the softening temperature was calculated as '1-'.

However, the load is 1 kg, and the test piece size is 13 mm x 1.
0 melting point and crystallization temperature: 5 mm x 5.2 mm: Differential scanning type 1 (Perkin-Elmer DSCl) +n, Mensha, So (Tm) according to ASTM + 417 and crystallization temperature (TC) mu
Fixed-1-ru. The measurement conditions and methods for determining Tm and Tc were as follows.

After holding at 260°C for 10 minutes, the maximum peak temperature on the exothermic side detected in the process of cooling down to 20°C at a cooling rate of 10''C/min is defined as To.

Subsequently, the maximum endothermic side peak temperature detected in the process of immediately heating at a temperature increase rate of 10° C./min is defined as 'rm.

The blowing agent (B) used in the method of the present invention has a decomposition start temperature exceeding the softening temperature of the poly-4-methyl-1-pentene (~, preferably a molecular start temperature of 10°C or higher than the softening temperature), A blowing agent that generates gas, specifically:
Azodicarbonamide, barium azodicarboxylate, N
, N'-dinitrosopentamethylenetetramine, trihydrazinotriazine, para-toluenesulfonyl heptamicarbazide, 4,4-oxybis(benzenesulfonylhydrazide), diphenylsulfone-6,6-cissulfonylhydracite, etc. Preferred are azodicarbonamide and N,N'-dinitrosopentamethylenetetramine, which have a high decomposition initiation temperature, sharp decomposition, and a large amount of decomposed gas.

If the decomposition start temperature of the blowing agent is below the softening temperature of the poly-4-methyl-1-pentene (A), the poly-4-methyl-1-pentene (A) will decompose during the process of compressing and heating the inside of the mold. is softened and deformed by compressive force, and the poly-4-methyl-1-
Since the blowing agent starts to decompose and gasify before the particles of pentene (～) and the blowing agent are tightly pressed together, the poly-4-methyl-1-pentene (～) softens and deforms due to compressive force. , the gas is the poly-4-methyl 1-.
The poly 4
- Methyl-1-pentene (A) is discharged outside of the pressed body and the gas cannot be used for foaming.

The method of the present invention comprises the poly-4-methyl-1-pentene (
The particles of A) and the foaming agent (■3) are mixed using, for example, a Henschel mixer, a ■-blender, a ribbon blender, a tumbler blender, etc. at a temperature below the decomposition start temperature of the foaming agent (B) to form foam. poly-4-methyl-1-pentene mixture (C), and a mold capable of compression, heating and preferably forced cooling, for example, a mold having an ordinary heating and pressure molding machine and an inner space capable of compressing the filling. A mold that combines a mold having a refrigerant flow path in the mold and a device that detects the temperature of the master mold and controls the flow rate of the refrigerant to control the temperature of the mold is manufactured using the blowing agent (B). ), preferably below the decomposition start temperature of the blowing agent (B) and above the softening temperature of the poly-4-methyl-1-pentene (A), and place the desired weight in the mold. The foamable poly-4-methyl-1-benzone mixture (C) is filled, the inside of the mold is compressed, and then the mold is heated with electric heat, heated oil, etc.
- After heating to the melting point of methyl-1-pentene (A) or higher, it is cooled, and when the temperature of the mold reaches the crystallization temperature of the poly-4-methyl-1-pentene (A) ± 10°C, Preferably, after holding for a certain period of time, the poly(4-methyl-1-pentene) is released or cooled to a temperature at least Nl"C lower than the crystallization temperature of the poly(4-methyl-1-pentene) (A).
- After crystallizing the methyl-1-pentene (/,), it is heated again so that the temperature of the mold ranges from the melting point of -20"C to the melting point of the poly4-methyl-1-pentene<ty, preferably 1
1 to 1! When the temperature reaches a temperature from -10°C to the melting point, it is preferably held for a certain period of time and then released to cause foaming.
A poly-4-methyl-1-pentene foam weighing more than 5 cm and 37 g is obtained.

As a method of compressing the inside of the mold, for example, a split mold consisting of two molds, an upper mold and a lower mold, is provided with four parts in the lower mold, and the recess is tilted so that the cross-sectional area decreases from the opening to the bottom part. Fill the concave portion with the filling material so that it rises above the openings of the four parts (i), and make it face the upper mold without the four parts, and pressurize it with the pressurizing force of the press molding machine or the pressurizing force with the screw tightening mechanism. A method of compressing the inside of the mold by applying pressure so that the upper and lower molds come into contact with each other using a tool, or a method of providing a convex part on the upper mold that faces and slidably fits into the four parts of the lower mold in the previous example. An example is a method of compressing the filler filled in the four parts of the lower mold using the same pressure as in the previous example, but the point is that the foamable poly-4-methyl-1-pentene mixture (C) is When the poly-4-methyl-1-pentene (A) particles in C> are softened by heating, they can be compressed to deform,
There is no limitation as long as the mold can be kept compressed and sealed until the mold is opened and foamed.

Note that the compression force that compresses the inside of the mold is
Medilu-1-pentene (Δ), the poly-4-methyl-1
- It is necessary to have a compressive force that is at least capable of deforming the pentene (A) at its softening temperature and suppressing the subsequent expansion of the decomposed gas of the blowing agent (B), but usually 2 or more of 50 Av spears is sufficient.

Furthermore, the characteristics of the main steps of the method of the present invention and changes in the state of the mixture of TPX and blowing agent in each step will be explained in detail. First, TPX particles and a foaming agent are mixed at a temperature equal to or higher than the decomposition starting temperature of the foaming agent to prepare a foamable TPX mixture. Next, the mixture is placed in a mold that can be compressed, heated, and cooled without going through the melt-kneading process that is common in conventional foaming methods, and the molding temperature is lower than the decomposition starting temperature of the blowing agent. The TPX is filled in the same state, compressed inside the mold, and then heated to a temperature higher than the melting point of the TPX. This +3
11 Expandable TP compressed in a mold during a thermal process
When the temperature of the X mixture is higher than the thickening temperature of the TPX,
The TPX grains in the mixture are deformed by the compression force in the mold and the thermal expansion force of the TPX itself, and are tightly compressed with each other and with the undecomposed blowing agent.

Subsequently, when the decomposition start temperature of the blowing agent is reached, decomposed gas is generated, but the scum is compressed and adhered to the TPX.
The gas is trapped between the grain interfaces and then, upon reaching the melting point of TPX, the T
Dissolved in the PX melt, the TPX particles themselves fuse to form a homogeneous foamable melt containing dissolved gas. With the steps up to this point, foaming 'rpχ1Jjl! The liquid is prepared under compression.

Next, the foamable TPX melt is cooled, or after cooling,
By reheating, the tensile strength corresponding to the foaming expansion force of the gas contained in the mold is increased to TP'1. However, in the former method of imparting tensile strength suitable for foaming to TPX by cooling, since TPX is crystalline, the foamable TPX melt is heated to a temperature close to the crystallization temperature of the TPX. By cooling and starting crystallization, the viscoelasticity of the TPX is increased, and at point R, when the tensile strength range suitable for foaming is reached, the mold is opened and foamed. On the other hand, in the latter method of giving TPX a tensile strength suitable for foaming by cooling and reheating the mold, the foamable TPX melt is cooled to a temperature sufficiently lower than the crystallization temperature of the TPX to crystallize it. After completing the process and once imparting viscoelasticity that exceeds the range of tensile strength suitable for foaming, the TPX crystals are partially melted by heating the TpX again to a temperature close to its melting point, thereby increasing the viscosity of the TPX. When the elasticity is reduced and the tensile strength range suitable for foaming is reached, the mold is opened.
Foam. Either of the above two methods may be used 1
゜That is, the main step of the manufacturing method of the present invention is to
trapping decomposed gas of a blowing agent having a decomposition temperature equal to or higher than the softening temperature between the TPX particles under heat and compression, and then incorporating the decomposed gas dissolved in TPX to prepare a foamable TPX melt; The tensile strength of TPX in the foamable TPX melt is determined by adjusting the temperature and preferably G'! during the crystallization process of the TPX or the remelting process after crystallization. Furthermore, by controlling the holding time at this temperature, the tensile strength range suitable for the foam is reached, and the foaming process and force is essentially zero by releasing 5JJ at point II. .

The amount of the foaming agent (B) mixed with poly-4-methyl-1-pentene (A) is appropriately selected depending on the density of the desired foam and the amount of gas generated by the foaming agent (B) used. It should be 1L, but is the foaming agent Azoshika-7+? In the case of Namide, a foam with a low expansion ratio (medium density, specific volume 5.5) is used.
or 1 (3cyn'/g) per 100 parts by weight of 4-methyl-1-pentene (A)
'7ft1.5 fi ks, 5 parts by weight, high expansion ratio foam (low density, specific volume 10 to 5oaR'/g)
Generally, it is sufficient to add 5 to 1 to 25 parts by weight. In addition,
The above specific volume and the volume of the foamed water per unit weight (unit: 33) divided by the weight of the foam (unit: g). :aR5/g). (The unit of specific volume is OC/g.

It is abbreviated as ) Poly4-methyl-1-pentene (in addition to the above-mentioned foaming agent (B), heat-resistant stabilizers, weather-resistant stabilizers, foaming aids, antistatic agents, surfactants, lubricants, oil agents, moisture absorbers) agents, pigments,
Dyes, inorganic fillers, inorganic or organic fibrous reinforcing phases, inorganic microhollow bodies, coupling agents, and acid-modified poly-4-methyl-1-pentene such as maleic acid or acrylic @ may be used without impairing the purpose of the present invention. They may be blended within a certain range.

The poly-4-methyl-1-pentene foam of the present invention has superior heat resistance compared to conventional foams such as polyethylene, polystyrene, and polypropylene, and retains the water resistance, electrical properties, etc. of polyolefin. The fragility, which is a drawback of heat-resistant foams such as phenolic resin foam and urea resin foam, has been improved, so it has the unprecedented feature of being a semi-rigid to soft foam and having high heat resistance. . Therefore, the poly-4-methyl-1-pentene foam of the present invention can be used as a high-temperature insulation material, a soundproof material in a high-temperature atmosphere, a vibration-proof material, a buffer material, a buoyancy material in a high-temperature liquid, and a buoyancy material in a high-temperature liquid or gas. Filter materials or sanitary materials Fl that undergo high-temperature heat treatment, such as heat sterilization and autoclaved steam sterilization, and their cushioning packaging materials, as well as lightweight or porous substrates that support or accommodate substances that are treated at high temperatures. It can be widely applied as containers, etc., and can be used for applications that could not be achieved with conventional foams.

Examples 1 to 6, Comparative Examples 1 to 2 MFR is 0.5 g710 min, softening temperature +7
0”C, melting point 230°C, crystallization temperature 210°C TPX
(1) Powder (product name TPX, brand name RT-18P:
(manufactured by Mitsui Petrochemical Industries, Ltd.) 90 parts by weight (hereinafter abbreviated as "parts"), a blowing agent (as a border, azodicarbonamide (trade name: Vinyhole AC #3 = Eiwa fhi) with a decomposition start temperature of 200°C 10 parts of a heat-resistant stabilizer (trade name: I/L/Ganox 1010: Chihakaiki Co., Ltd.) 111
0.2 part of IFRS stabilizer (trade name snT "Takegu", manufactured by Takeda Pharmaceutical Co., Ltd.), 0.2 part of MIKILY (trade name Mymixer MX-M2, manufactured by Matsushita Electric Industrial Co., Ltd.)
The mixture was mixed for 6 minutes using a foaming TPX compound 1).

On the other hand, a metal lower mold (hereinafter referred to as the lower mold), which has four generally disc-shaped parts on the upper side with an opening diameter of 5Q mm, a bottom diameter of 44 mm, and a depth of 2 mm, was heated by a pressing machine (product name: It was attached to the movable (F) mold plate of a one-cycle automatic molding machine Model 8FA-50 (manufactured by Shindo Metal Industry Co., Ltd.), and another metal upper mold (hereinafter referred to as the upper mold) that did not have four parts on the lower surface was attached. Fixation of the heating and pressure molding machine] A set of molds (hereinafter abbreviated as foam molds) configured by being suspended and attached to a mold plate is preheated to a temperature of 180°C, and the foam molding After 3.5 g of the foamable TPX medium mixture l) was filled into the recess provided on the upper surface of the lower mold, the movable old mold plate of the heating and pressure molding machine was raised and activated. Hydraulic pressure 15
The inside of the mold was compressed by pressurizing the foaming mold at 0 kg/an2, and then heated to 240°C to soften the TPX (1) powder (completion temperature 170"C).
), pressure bonding between the TPX (1) powder and the foaming agent (B) and sealing of the mold due to the compressive force of the mold and the thermal expansion of the TPX itself, and then the foaming agent (B) Decomposition gas generation due to thermal decomposition (decomposition temperature range 200-210°
C) and melting in the TPX (melting point 2 to 0"C) is repeated 100 times, and then a mixed fluid of air and cold water is poured into the cooling medium channels provided in the upper and lower molds of the foam mold, respectively. The upper/lower molds were cooled to various temperatures shown in Table 1 near the crystallization temperature (210"C) of the TPX by controlling the flow rate, held for 3 minutes, and then heated and pressurized. The foaming mold is opened by removing the hydraulic pressure of the molding machine 4, and the process of depressurizing and foaming is repeated. The results are shown in Table 1 along with the holding temperature C or lower when the mold is opened (abbreviated as cooling foaming temperature). are summarized in

Table 1 As shown in Table 1, the crystallization temperature (
210°C) ±10°C when the mold is opened,
A good highly foamed product was obtained.

Examples 4 to 7, Comparative Examples 3 to 4 Using the same foamable TPX (I) mixture (cl) as in Example 1, the foaming process of Example 1 up to the start of cooling was completely the same as in Example 1. After doing the same, the subsequent steps were changed and the upper/lower molds were cooled to +80'C and the TPX (1
), then the melting point of the TPX (1) (260 °C
) After heating to various temperatures shown in Table 2, the mold is immediately opened by removing the upper/lower mold suppression, and the foaming process is repeated. As can be seen from Table 2, when the mold was opened in the temperature range from -20°C to the melting point of T P X (1), good foaming was achieved. I got a body.

Example 8, Comparative Example 5 In Example 6, the temperature of the mold (hereinafter abbreviated as preheating temperature) when filling the foamable T P Table 3 shows the results obtained by repeating the same operations as in Example 6 except for the above steps.

Table 5 By comparing the example date in Table 6 with Example 6 in Table 2, the preheating temperature was determined to be the softening temperature (1
Although a highly foamed product can be obtained even if the temperature is lower than 70°C, the specific volume of the foam is lower than the softening temperature of Tpx (1) (+
The temperature is lower than that of Example 6, which was preheated at 80"C), and it can be seen that the preheating temperature is preferably equal to or higher than the softening temperature of the TPX (1). Also, the preheating temperature is lower than that of Example 6, which was preheated at 80"C. When the temperature is higher than the decomposition start temperature (200''C) of the foaming agent (B), the decomposition gas of the foaming agent (B) is generated immediately after filling the foaming TPX (1) mixture (C1) into the mold. Even after pressurizing, the decomposed gas traced the gaps between the unsoftened and unpressed Tpx (1) grains in the portions that did not contact the preheated mold and was lost outside the mold, and no foam was obtained.

Example 9, Comparative Examples 6 to 7 In Example 6, the cooling temperature was 200°C to 220°C.
Table 4 shows the results obtained by repeating the same operations as in Example 6, except that .

Table 4 As can be seen from Example 6 and Table 4, when the cooling temperature is 10°C or more lower than the crystallization temperature (21°C) of the T P I got a body.

Comparative Example 8 In Example B, the blowing agent (13) was heated to a decomposition temperature of 100
The same procedure as in Example 6 was carried out, except for changing the temperature to azobisinbutyronitrile (trade name: Cellmic~B, manufactured by Sankyo Kasei Co., Ltd.) at °C. The decomposed gas of the agent is dispersed through the gap between the upper and lower molds, and the foaming ability is lost.
No foam was obtained.

Examples 10 to 18 In place of TPX (1) in Example 6, various TPXs (all made by Mitsui Petrochemical Industries, Ltd.) with different melt flow rate (MFII) shown in Table 5 were used. The foam molding was repeated in the same manner as in Example 6 except for the operating conditions shown in Table 5. As can be seen from the foaming Table 5 in Table 5, the MFR value of ↑px was 0-5 g710 mlH
Good foams were obtained in a range of about 50 g/+0 m1n or less.

Examples 19 to 24 In place of TPX (1) in Example 6, various TPXs shown in Table 6 with mainly different thermal properties (all manufactured by Mitsui Petrochemical Industries, Ltd.) were used to produce the results shown in Table 6. The results of repeating foam molding in the same manner as in Example 6 except for the operating conditions shown are shown in the sixth example.
As shown in Table 6 in the foam specific volume column,
Even if the melting point of the TPX used is different, the re-heating foaming temperature can be changed.
A good foam can be obtained by controlling the temperature in the range from -20°C to the melting point of the TPX, and the lower the melting point of the TPX, the higher the foaming temperature at which the foam of the TPX can give a high specific volume. Wide range.

Applicant: Mitsui Petrochemical Industries, Ltd. Agent Kazu Yamaguchi

Claims (2)

[Claims] (1) Poly4-methyl-1-pentene (A) and poly4
- Methyl-1-pentene (mix with a blowing agent (B) having a decomposition start temperature exceeding the softening temperature of N) and set the temperature of the mold in a mold that can be compressed, heated and cooled. After filling the mold by keeping the temperature at or below the decomposition start temperature of poly-4-methyl-1-pentene (A), the mold is then heated to a temperature higher than the melting point of the poly-4-methyl-1-pentene (A) to decompose the blowing agent (H), followed by a cooling cylinder. ,
The temperature of the mold is the poly-4-methyl-1-pentene (/V)
When the crystallization temperature of the poly-4-methyl-1-pentene (N) reaches ±10"C, the mold is opened or cooled to a temperature at least 10 °C lower than the crystallization temperature of the poly-4-methyl-1-pentene (N), then heated again, and the temperature of the mold is lowered. is the poly-4-methyl-1-pentene (
A method for producing poly-4-methyl-1-penhon foam, which comprises foaming by opening the foam when the temperature reaches a temperature range from -20° C. to the melting point of N. (2) A poly-4-methyl-1-pentene foam, characterized in that the foam has a specific volume of 3.5 ffi3/g or more.