CN101875739A - Polypropylene-based resin expanded particle formed body and manufacture method thereof - Google Patents

Abstract

The present invention relates to polypropylene-based resin expanded particle formed body and manufacture method thereof.Mechanical properties such as the fusion character excellence that provides expanded particle mutual is provided the object of the invention, and the skin section of expanded particle formed body and inner density difference are little, compressive strength and outward appearance are all than excellent in the past low range polypropylene-based resin expanded particle formed body.The polypropylene-based resin expanded particle formed body, it is polypropylene-based resin expanded particle to be filled in carry out the expanded particle formed body that hot briquetting forms in the mould, it is characterized in that, the density of this expanded particle formed body is 60g/L～450g/L, the fusion rate of polypropylene-based resin expanded particle is more than 50%, the skin section density of this expanded particle formed body is 1～2 divided by the density ratio of the internal density gained of this formed body, and the polypropylene-based resin expanded particle that forms this expanded particle formed body is the preferential progressive type polypropylene-based resin expanded particle of fusion that satisfies specified conditions.

Description

Polypropylene-based resin expanded particle formed body and manufacture method thereof

Technical field

The present invention relates to a kind of polypropylene-based resin expanded particle formed body and manufacture method thereof, the particularly skin section of expanded particle formed body and the inner little high density poly propylene resin expanded particle formed body of density difference, and highdensity polypropylene-based resin expanded particle is being carried out when in-molded, can under the mold temperature lower, obtain the manufacture method of the expanded particle formed body of expanded particle formed body than in the past in-molded temperature.

Background technology

Acrylic resin, because it has excellent character such as physical strength, thermotolerance, processibility, burning, reproducibility, so Application Areas constantly enlarges.Equally, polypropylene-based resin expanded particle is carried out the in-molded polypropylene-based resin expanded particle formed body that forms, can not lose the excellent properties of above-mentioned acrylic resin, characteristics such as its resiliency, thermal insulation, light weight be can also give in addition, wrapping material, material of construction or impact absorption material for use with vehicle etc. therefore are widely used in.In addition,, need accurate dimensions precision and high strength, therefore envision high-density, i.e. the increase in demand of the polypropylene-based resin expanded particle formed body of low expansion ratio for the packaging pallet of electronic unit, automobile lightweight parts etc.

Highdensity polypropylene-based resin expanded particle formed body can be by carrying out in-molded obtaining to the big expanded particle of apparent density.But in this was in-molded, because the big polypropylene-based resin expanded particle of apparent density carries out second time of foaming, simultaneously, therefore the fusion mutually of the surface of expanded particle, only made the expanded particle melt surface have difficulties.

In the prior art, the deviation that reduces the apparent density of polypropylene-based resin expanded particle by use has been regulated the expanded particle of average bubble number, thereby improve the second time of foaming of expanded particle, the mutual fusion character (melting adhesivity) on expanded particle surface, the method (patent documentation 1) of the expanded particle formed body of manufacturing outward appearance and excellent rigidity is just in practical application.

But, be more than 60 (g/L) to density, when particularly the above high density poly propylene resin expanded particle formed body of 100 (g/L) carries out moulding, the low range expanded particle that is used to obtain this expanded particle formed body is compared with powerful expanded particle, and the mutual fusion character of expanded particle reduces easily when in-molded.Thus, even make the good expanded particle second time of foaming of formed body appearance by the Heating temperature that improves when in-molded, it is not enough that the inside fusion character of this expanded particle formed body also becomes easily.Therefore, in order to obtain the sufficient expanded particle formed body of this fusion character, the filling rate of compression when improving expanded particle and be filled in the mould of need taking measures, and further improve as the water vapor pressure of the saturated steam of heating medium etc.

Therefore in this case, if improve this water vapor pressure, then Heating temperature also becomes higher, has the cooling time when in-molded elongated, the problem that productivity descends.In addition, because the expanded particle formed body of gained, the saturated steam that uses high water vapor to press carries out in-molded, therefore, there is the bubble of expanded particle formed body skin section to break and densification, the inside of gained expanded particle formed body and skin section produce density difference, and the insufficient problem of physical strength such as compression rerum natura.

[patent documentation 1] TOHKEMY 2000-63556 communique

Summary of the invention

The fusion character excellence that provides a kind of expanded particle mutual is provided the object of the invention, mechanical properties such as the skin section of expanded particle formed body and inner density difference are little, compressive strength and outward appearance are all than the polypropylene resin foam particle formed body of excellent in the past low expansion ratio.

In addition, the object of the invention is to provide a kind of toughness as polypropylene-based resin expanded particle formed body feature, thermotolerance, easy excellent properties of reproducibility etc. can not damaged, in-molded by carrying out under than low in the past Heating temperature, thus the manufacture method of the polypropylene-based resin expanded particle formed body of low expansion ratio stably made with excellent rerum natura.

The object of the invention is to develop a kind of polypropylene-based resin expanded particle, it can be under than the low mold temperature of the mold temperature of in the past polypropylene-based resin expanded particle, under the situation of not damaging the characteristic that polypropylene-based resin expanded particle formed body in the past had, obtain the also expanded particle formed body of excellent low range of mechanical properties such as the mutual fusion character excellence of expanded particle, compressive strength.In order to realize this purpose, the applicant is to the relation between the mechanical properties of the crystal structure of expanded particle and expanded particle formed body, relation between the behavior when in-molded of the crystal structure of expanded particle and expanded particle, and in-molded method etc. is studied, found that, expand to low temperature side by the in-molded mold temperature scope of carrying out that makes expanded particle, in addition, rate of compression when the adjusting expanded particle is filled in the mould therefor when in-molded, can stably obtain having the expanded particle formed body of the low expansion ratio of excellent rerum natura, and finish the present invention thus.

That is to say that the invention that the present invention is put down in writing with following (1) and (2) is main points.

(1) a kind of polypropylene-based resin expanded particle formed body, it is polypropylene-based resin expanded particle to be filled in carry out the expanded particle formed body that hot briquetting forms in the mould, it is characterized in that,

The density of this expanded particle formed body is 60g/L～450g/L, and the fusion rate (melting rate) of polypropylene-based resin expanded particle is more than 50%, and the skin section density of this expanded particle formed body is 1～2 divided by the density ratio of the internal density gained of this formed body,

The polypropylene-based resin expanded particle that forms this expanded particle formed body is characterised in that at least one that satisfies in following condition 1～condition 3,

Condition 1: have following crystal structure, that is, (Hot a fluid stream differential is walked at heat flux differential scanning calorimetry Hot Liang Measuring is fixed) in, with 2 ℃/minute heat-up rates polypropylene-based resin expanded particle is heated to the DSC curve of 200 ℃ of gained from normal temperature, appearance is 100 ℃～140 ℃ a main endotherm(ic)peak with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at the endotherm(ic)peak more than 2 of this main endotherm(ic)peak high temperature side;

Condition 2: polypropylene-based resin expanded particle is 100 ℃～140 ℃ low melting point acrylic resin and 20～2 weight part fusing points than the mixture of the high high-melting-point acrylic resin more than 20 ℃ of this low melting point acrylic resin as substrate resin with 80～98 weight part fusing points;

Condition 3: in heat flux differential scanning calorimetry, after with 10 ℃/minute heat-up rates polypropylene-based resin expanded particle being heated to 200 ℃ from normal temperature, with 10 ℃/minute cooling rates it is cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with 10 ℃/minute heat-up rate, from 80 ℃ to being 0.55～0.80 divided by the heat ratio of total endotherm(ic)peak heat gained than the fusion heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle.

(2) a kind of manufacture method of polypropylene-based resin expanded particle formed body, it is the manufacture method that polypropylene-based resin expanded particle is filled in the expanded particle formed body that carries out hot briquetting in the mould,

The apparent density of this polypropylene-based resin expanded particle is 100g/L～720g/L, and simultaneously, it satisfies in above-mentioned condition 1～condition 3 at least one, and the rate of compression of this polypropylene-based resin expanded particle when filling in mould is 0～15%.

Polypropylene-based resin expanded particle formed body of the present invention, when it is characterized in that expansion ratio is low, the density difference of the skin section of expanded particle formed body and inside is littler than in the past, and therefore, because this epoch-making feature, its compressive strength is also excellent.

In addition, expanded particle formed body of the present invention, the fusion character mutual owing to expanded particle is good, so other mechanical properties is also excellent.Further, this expanded particle formed body in its surface, the gap that is called space (viod) between venting hole mark, expanded particle is little, the smoothness excellence, outward appearance is good.

Manufacture method according to polypropylene-based resin expanded particle formed body of the present invention, it can be lower than under the in-molded heating condition of prior art in temperature, form the low expansion ratio expanded particle formed body of the mutual fusion character excellence of expanded particle, therefore, can shorten cooling time after the heating when in-molded, and shorten the in-molded time thus.

In addition, manufacturing method according to the invention, in in-molded, do not need to heat, therefore by the saturated steam that excess steam is pressed, can reduce the mold pressure of shaper, do not need the weather resistance of mould is increased to more than the necessary degree, can reduce the thickness of mould, very big in the manufacturing cost and the advantage aspect the weather resistance of shaper and mould, in-molded comparing in the past can significantly be cut down cost of energy.

In addition, manufacturing method according to the invention can obtain comparing with expanded particle formed body in the past, fusion rate height, and the density of expanded particle formed body skin section and inside is than little, and the also excellent polypropylene-based resin expanded particle formed body of compression rerum natura.

Description of drawings

[Fig. 1] is illustrated in the manufacture method of expanded particle formed body of the present invention, a DSC curve shows figure of polypropylene-based resin expanded particle.

[Fig. 2] is illustrated in the manufacture method of expanded particle formed body of the present invention, the 2nd DSC curve shows figure of polypropylene-based resin expanded particle.

Nomenclature

Be equivalent to 80 ℃ point on the α DSC curve

The point that is equivalent to the fusion end temp on the β DSC curve

The paddy portion at γ low temperature side peak and high temperature side peak

δ straight line alpha-beta and from the intersection point of the vertical line that γ drew

Te fusion end temp

a ₁Main endotherm(ic)peak

a ₂The endotherm(ic)peak of main endotherm(ic)peak high temperature side

a ₃The endotherm(ic)peak of main endotherm(ic)peak high temperature side

TmA, PTmA endotherm(ic)peak summit temperature

Δ Ha master endotherm(ic)peak heat

Δ Hb endotherm(ic)peak a ₂The endotherm(ic)peak heat

Δ Hc endotherm(ic)peak a ₃The endotherm(ic)peak heat

Embodiment

Below, manufacture method and (3) polypropylene-based resin expanded particle formed body of employed among the present invention (1) polypropylene-based resin expanded particle, (2) polypropylene-based resin expanded particle formed body described.

(1) polypropylene-based resin expanded particle

As expanded particle used in in-molded, following expanded particle is arranged: have by the foamable particle, at first form expanded particle interfused state mutually, then form the character of the state that expanded particle can second time of foaming expanded particle (below, the expanded particle that will have this character is called the preferential progressive type expanded particle of fusion), with have by the foamable particle, at first form the state that expanded particle can second time of foaming, then form the expanded particle expanded particle of the character of interfused state (below, the expanded particle that will have this character is called the preferential progressive type expanded particle of second time of foaming) mutually.In research of the present invention, obtained a kind of like this viewpoint, that is, under than low in the past Heating temperature, expanded particle is carried out fusing preferential progressive type expanded particle than the preferential progressive type expanded particle of second time of foaming more preferably when in-molded.

Above-mentioned when in-molded, fuse the reason that preferential progressive type expanded particle more preferably uses than the preferential progressive type expanded particle of second time of foaming, as described below.

If when in-molded, use the preferential progressive type expanded particle of second time of foaming, then in the heating process when in-molded, because the second time of foaming of expanded particle preferentially carries out, therefore the expanded particle gap that is filled in the mould is crowded with easily, hinder water vapour to flow into, pass through the gap between expanded particle easily, the result has hindered the mutual fusion of expanded particle.

And fuse the principal element that preferential progressive type expanded particle be difficult to produce the above-mentioned obstruction that the preferential progressive type expanded particle of second time of foaming reflected.In addition, no matter be the preferential progressive type expanded particle of fusion, or the preferential progressive type expanded particle of second time of foaming, only otherwise use the big resin of fusing point difference to cover special operations such as expanded particle surface, then the mutual fusion temperature of expanded particle and second time of foaming temperature just do not have the bigger temperature head shown in aftermentioned embodiment and the comparative example.

By using this expanded particle, can carry out under than low in the past Heating temperature in-molded, can also obtain the mutual fusion character excellence of expanded particle, the skin section of expanded particle formed body and inner density difference are little, and mechanical properties, expanded particle formed body that outward appearance is also excellent.

The preferential progressive type polypropylene-based resin expanded particle of fusion among the present invention can be distinguished by following operation.

With stacking volume (Song Ti Plot) be about 100cm ³Polypropylene-based resin expanded particle to put into volume be 5L (liter) and have in the pressure vessel of pressure regulator valve, then, use the saturated steam of the melt temperature that is equivalent to this polypropylene-based resin expanded particle, heat the operation in 10 seconds of this expanded particle.Based on apparent density by the polypropylene-based resin expanded particle after the heating of this operation gained, with the apparent density of polypropylene-based resin expanded particle before the heating of putting in the pressure vessel, if with the apparent density of the apparent density gained of the apparent density of the polypropylene-based resin expanded particle before the heating polypropylene-based resin expanded particle after divided by heating than (ρ _R) greatly about 1.0～1.7 scope, the polypropylene-based resin expanded particle of then putting in the pressure vessel is the preferential progressive type polypropylene-based resin expanded particle of fusion.

In the preferential progressive type expanded particle of fusion, preferably when in-molded, have suitable second time of foaming power, therefore above-mentioned apparent density is than (ρ _R) more preferably 1.1～1.6, and more preferably 1.2～1.5.

In addition, in the present invention, the above-mentioned melt temperature of expanded particle, be to use heat flux differential scanning calorimetry device (hereinafter referred to as the DSC device) and measure the value of gained according to " after carrying out certain thermal treatment, the situation of mensuration melt temperature " method of being put down in writing among the JIS K7121 (1987).Specifically, this melt temperature, be as sample with 1～3mg polypropylene-based resin expanded particle, and according to heat flux differential scanning calorimetry method (hereinafter referred to as DSC), after with the heat-up rate of 10 (℃/minute) it being warming up to 200 ℃ from normal temperature, speed with 10 (℃/minute) is cooled to 30 ℃ with it, and then it is warming up to 200 ℃ from 30 ℃ with the heat-up rate of 10 (℃/minute), by the summit temperature of the determined endotherm(ic)peak of differential scanning calorimetry curve (DSC curve) of gained at this moment.In addition, when in the DSC curve, having a plurality of endotherm(ic)peak, with the summit temperature of the endotherm(ic)peak of maximum area as melt temperature.

In addition, above-mentioned apparent density is than (ρ _R) detailed determination step, as described below.

Stacking volume is about 100cm ³The known expanded particle of apparent density (heating before expanded particle) join in 5L (liter) pressure vessel with pressure regulator valve, use is equivalent to the saturated steam of the water vapor pressure of expanded particle melt temperature, in this airtight container, this expanded particle was heated for 10 seconds, the expanded particle after obtaining thus heating.

In addition, the apparent density of the expanded particle before the heating, be with expanded particle under the normal pressure, temperature be 23 ℃, relative humidity be place under 50% the condition carry out status adjustment more than 48 hours after, use wire netting etc. that this expanded particle group of weight as W (g) sunk in the graduated cylinder that adds entry, obtain this expanded particle group's volume: V (L) by the water level ascending amount, and the value of being obtained divided by this expanded particle group's volume (W/V) with this expanded particle group's weight.

In addition, the apparent density of the expanded particle after the heating, be will the expanded particle of above-mentioned pressure vessel internal heating gained in 10 second under the normal pressure, temperature be 23 ℃, relative humidity be place under 50% the condition carry out status adjustment more than 48 hours after, use wire netting etc. that this expanded particle group of weight as W (g) sunk in the graduated cylinder that adds entry, obtain this expanded particle group's volume: V (L) by the water level ascending amount, and the value of being obtained divided by this expanded particle group's volume (W/V) with this expanded particle group's weight.

Polypropylene-based resin expanded particle of the present invention has the apparent density of 100～720 (g/L).The upper limit of the apparent density of this expanded particle is considered to determine according to the angle of fundamental characteristics such as the light weight that improves gained expanded particle formed body, resiliency, is preferably 500 (g/L), more preferably 300 (g/L).On the other hand,, then be difficult to obtain purpose expanded particle formed body of the present invention, so the lower limit of apparent density is preferably 120 (g/L), more preferably 150 (g/L) if the apparent density of expanded particle is low excessively.

In addition, the apparent density of above-mentioned expanded particle, be in the graduated cylinder that has added water, use wire netting etc. to sink to the expanded particle group of weight as W (g), obtain this expanded particle group's volume: V (L) by the water level ascending amount, and the value of being obtained divided by this expanded particle group's volume (W/V) with this expanded particle group's weight.

Obtain the method for this polypropylene-based resin expanded particle, be documented in " (1-5) manufacture method of polypropylene-based resin expanded particle " item.

Constitute the substrate resin of polypropylene-based resin expanded particle of the present invention, as long as can satisfy structure condition of the present invention, no matter then it is alfon, propylene-based block copolymer, or propylene is a random copolymers, can use.In addition,, comprise propylene and ethene and/or carbonatoms and be the multipolymer of 4～20 alpha-olefin, can enumerate the multipolymer of propylene and ethene, 1-butylene, 1-amylene, 1-hexene, 1-octene, 4-methyl isophthalic acid-butylene etc. as the aforesaid propylene multipolymer.The aforesaid propylene multipolymer can be copolymers such as propylene-ethylene random copolymers, propene-1-butene random copolymers, also can be terpolymers such as propylene-ethylene-butene random copolymers.In addition, polypropylene copolymer preferably is more than the 70 weight %, further is 80～99.5 weight % from the structural unit content of propylene in this multipolymer, and the structural unit content that by ethene and/or carbonatoms is 4～20 alpha-olefin gained is below the 30 weight %, be preferably the acrylic resin of 0.5～20 weight %.

By making expanded particle of the present invention is the preferential progressive type polypropylene-based resin expanded particle of above-mentioned fusion, can carry out under than the low mold temperature of the in-molded temperature of polypropylene-based resin expanded particle in the past in-molded, simultaneously, this expanded particle is being used for when in-molded, can stably obtaining outward appearance, the mutual excellent expanded particle formed bodys such as fusion character of expanded particle.In addition, satisfy aforementioned apparent density, can obtain the expanded particle formed body of excellent rigidity by making this expanded particle.

The preferential progressive type polypropylene-based resin expanded particle of above-mentioned fusion, method that for example can be by the method for regulating the expanded particle crystal structure, the separated foam rate of regulating expanded particle, bubble diameter, epidermal area thickness etc. obtains.

The preferential progressive type polypropylene-based resin expanded particle of fusion of the present invention is at least one the expanded particle that satisfies condition 1～condition 3 defined, following record among the present invention.

(1-1) satisfy condition 1 polypropylene-based resin expanded particle (P1)

The condition 1 of polypropylene-based resin expanded particle given to this invention, be to have following crystal structure, promptly, in DSC measures, use the DSC device with the heat-up rate of 2 (℃/minute) with 1～3mg expanded particle from a DSC curve of normal temperature (general 25 ℃) gained when being heated to 200 ℃, appearance is 100 ℃～140 ℃ a main endotherm(ic)peak with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at the endotherm(ic)peak more than 2 of this main endotherm(ic)peak high temperature side.

Be noted that, in the DSC of expanded particle measures, be generally the heat-up rate of 10 (℃/minute) with respect to employing, and adopt the reason of the heat-up rate of 2 (℃/minute), be owing to have or not the peculiar crystal structure of expanded particle in order to identify, promptly, whether expanded particle has the specific crystal structure that occurs 3 above endotherm(ic)peaks in a DSC curve, need be than the slow down rate of heating condition of DSC of normal conditions, and according to different types of crystal, improve the resolving power of endotherm(ic)peak and measure, therefore, the heat-up rate that is fit to is 2 (℃/minute).

As the satisfy condition acrylic resin of substrate resin of 1 expanded particle (P1) of formation, as long as satisfy condition 1, then can comprise single resin, also can comprise hybrid resin, this is not particularly limited.

As this single resin, can enumerate and use metallocene catalyst to carry out the acrylic resin etc. of multistage polymerization (multistage coincidence) gained.In addition, as this hybrid resin, can enumerate the mixture etc. of mixture, low melting point acrylic resin and the high-melting-point acrylic resin of the acrylic resin of above-mentioned multistage polymerization gained and other acrylic resin.In addition, for substrate resin, no matter single resin or hybrid resin, the viewpoint of the expanded particle with above-mentioned specific crystal structure of being easy to get to calmly considers that all preferred the use adopts metallocene class polymerizing catalyst to carry out the acrylic resin of polymerization gained.

In condition 1, aforementioned main endotherm(ic)peak comes from the watery fusion composition in the resin that constitutes expanded particle (P1).On the other hand, the endotherm(ic)peak more than 2 that is arranged in this main endotherm(ic)peak high temperature side comes from the high-temperature fusion composition of the resin that constitutes expanded particle (P1).

When the substrate resin of expanded particle (P1) comprises single resin, formed low melting point polypropylene composition when this main endotherm(ic)peak comes from as the acrylic resin polymerization of substrate resin, formed high-melting-point polypropylene composition when the endotherm(ic)peak more than 2 that is positioned at this main endotherm(ic)peak high temperature side comes from this acrylic resin polymerization, or the high-melting-point composition that generated of the isothermal crystal operation of this composition and the low melting point polypropylene composition that forms aforementioned main endotherm(ic)peak (for the isothermal crystal operation etc., describe hereinafter).

In addition, when the substrate resin of expanded particle (P1) comprises hybrid resin, this main endotherm(ic)peak comes from the low melting point acrylic resin (P1a) that forms hybrid resin, the endotherm(ic)peak more than 2 that is positioned at this main endotherm(ic)peak high temperature side comes from other more dystectic acrylic resin (P1b), or the high-melting-point composition that generated of the isothermal crystal operation of this dystectic acrylic resin (P1b) and the low melting point acrylic resin (P1a) that forms aforementioned main endotherm(ic)peak (for the isothermal crystal operation etc., describe hereinafter).

In addition, because the summit temperature of main endotherm(ic)peak is near the melting point resin as the acrylic resin of the substrate resin of expanded particle (P1), therefore in a DSC curve of above-mentioned heat-up rate gained with 2 (℃/minute), the summit temperature that endotherm(ic)peak occurs is the situation of the main endotherm(ic)peak of 100～140 ℃ of temperature ranges, when substrate resin is single resin, the expression principal constituent is low-melting polypropylene composition, when substrate resin was hybrid resin, the expression principal constituent was low-melting acrylic resin.

This expanded particle (P1) shows aforementioned distinctive DSC curve, because the existence of this main endotherm(ic)peak, can reduce the fusion temperature of the expanded particle when in-molded.In addition, the effect that limits expanded particle second time of foaming when in-molded has been played in the existence of 2 above endotherm(ic)peaks of this main endotherm(ic)peak high temperature side.Therefore, this expanded particle (P1) is the preferential progressive type expanded particle of fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and in addition, the mutual fusion character of expanded particle has also improved when in-molded.

The expanded particle (P1) that satisfies above-mentioned condition 1 is to have the expanded particle that can measure the specific crystal structure of confirming by above-mentioned DSC, and this detailed confirmation method is recorded in hereinafter.

Use the DSC device explanatory view of 1～3mg expanded particle representational DSC curve of gained when normal temperature is heated to 200 ℃ to be shown in Fig. 1 with the heat-up rate of 2 (℃/minute).In the DSC of Fig. 1 curve, a ₁, a ₂, a ₃Represent endotherm(ic)peak respectively.In addition, total endotherm(ic)peak heat (Δ H) of an above-mentioned DSC curve can followingly be obtained.

As shown in Figure 1, connect on the aforementioned DSC curve corresponding to 80 ℃ some α with corresponding to the some β on the DSC curve of resin fusion end temp Te, straight line (alpha-beta) draws, with it as baseline, and will be equivalent to this baseline and DSC curve surround part area heat as total endotherm(ic)peak heat (Δ H) (J/g).The heat at above-mentioned peak calculates and calculates automatically based on peak area use DSC device.In addition, total endotherm(ic)peak heat (Δ H) is preferably the scope of 40～120J/g, the scope of 45～100 (J/g) more preferably, and be preferably the scope of 45～85 (J/g) especially.

Satisfy condition 1 expanded particle (P1) as shown in Figure 1, the endotherm(ic)peak more than 3 occurs on a DSC curve, and the heat of each endotherm(ic)peak (Δ Ha, Δ Hb, Δ Hc......), can obtain by the part method of area analysis hereinafter described.

Based on Fig. 1 declaratives method of area analysis.On the DSC of gained curve, connect corresponding to the some α on 80 ℃ the DSC curve with corresponding to the some β on the DSC curve of resin fusion end temp Te, the line segment that draws (alpha-beta).Then, from the viewed peak a of the minimum low-temp. portion of temperature ₁With with peak a ₁Adjacent peak a ₂Between the DSC curve of the lowest point part on some γ ₁, the straight line parallel that draw with the longitudinal axis of figure, with the intersection point of itself and aforementioned line segment (alpha-beta) as δ ₁In addition, owing to observe and peak a ₂Adjacent peak a ₃, from peak a ₂With with peak a ₂Adjacent peak a ₃Between the DSC curve of the lowest point part on some γ ₂, the straight line parallel that draw with the longitudinal axis of figure, with the intersection point of itself and aforementioned line segment (alpha-beta) as δ ₂After, observing peak a ₄, peak a ₅, peak a ₆... the time, repeat same operation.When determining the endotherm(ic)peak area, constitute the boundary line at each peak by the line segment (δ n-γ n) (n is the integer more than 1) of aforesaid operations gained.

Therefore, corresponding to the area at each peak of endotherm(ic)peak heat, in Fig. 1, for peak a ₁, be expression peak a ₁DSC curve, line segment (δ ₁-γ ₁) and line segment (α-δ ₁) area that surrounded, for peak a ₂, be expression peak a ₂DSC curve, line segment (δ ₁-γ ₁), line segment (δ ₂-γ ₂) and line segment (δ ₁-δ ₂) area that surrounded, for peak a ₃, be expression peak a ₃DSC curve, line segment (δ ₂-γ ₂) and line segment (δ ₂-the area that β) surrounded.After, observing peak a ₄, peak a ₅, peak a ₆... the time, also can determine peak area by identical main points.Therefore, the heat at each peak (Δ Ha, Δ Hb, Δ Hc......) J/g based on the area at above-mentioned definite each peak, uses the calculation of DSC device and calculates automatically.In addition, in Fig. 1, total endotherm(ic)peak heat (Δ H) is equivalent to the heat summation (Δ H=Δ Ha+ Δ Hb+ Δ Hc) of each endotherm(ic)peak.

In addition, in the said determination method, in order to draw as the line segment (alpha-beta) of baseline, will with 80 ℃ of corresponding reasons of temperature as the some α on the DSC curve, be owing to be starting point with point corresponding to 80 ℃, with corresponding to the point of the fusion end temp baseline as terminal point, it is suitable for the heat that reproducibility well and is stably obtained endotherm(ic)peak.

Satisfy condition 1 expanded particle (P1) has in an aforementioned DSC curve, summit temperature (PTmA) occurs and is shown as the crystal structure that 100～140 ℃ and endotherm(ic)peak heat are 70～95% main endotherm(ic)peak of total endotherm(ic)peak heat (Δ H).Therefore, in the DSC curve of the expanded particle of Fig. 1, endotherm(ic)peak a ₁Represent main endotherm(ic)peak.In addition, this expanded particle (P1) has in a DSC curve, the crystal structure of 2 above endotherm(ic)peaks occurs at this main endotherm(ic)peak high temperature side.Therefore, in the DSC curve of the expanded particle of Fig. 1, endotherm(ic)peak a ₂, a ₃Expression is than main endotherm(ic)peak a ₁More be positioned at 2 endotherm(ic)peaks of high temperature side.

In 1 the expanded particle (P1) of satisfying condition, it is 70～95% of total endotherm(ic)peak heat (Δ H) that summit temperature (PTmA) is shown as 100～140 ℃ and endotherm(ic)peak heat, be meant in the endotherm(ic)peak more than 3 that in an aforementioned DSC curve of expanded particle, is occurred, be shown as any endotherm(ic)peak of 100～140 ℃ for summit temperature (PTmA), this endotherm(ic)peak heat with respect to the percentage of total endotherm(ic)peak heat (Δ H) (for example, in Fig. 1, (Δ Ha/ Δ H) * 100) be 70～95%.

In addition, from the thermotolerance viewpoint of gained expanded particle formed body and the viewpoint that further reduces the mold temperature when in-molded take all factors into consideration, endotherm(ic)peak summit temperature (PTmA) of this main endotherm(ic)peak is preferably 105～135 ℃, and more preferably more than 110 ℃ and less than 125 ℃.

In addition, from of the equilibrated viewpoint consideration of rerum naturas such as the physical strength that improves gained expanded particle formed body, thermotolerance with expanded particle in-molded property at low temperatures, in 1 the expanded particle (P1) of satisfying condition, the endotherm(ic)peak heat of this main endotherm(ic)peak is preferably 80～95% of total endotherm(ic)peak heat (Δ H), and more preferably 85～92%.

2 above endotherm(ic)peaks that high temperature side occurred in this main endotherm(ic)peak, can be by selecting the mixture of multiple acrylic resin, or selective polymerization catalyzer or polymerizing condition etc. and form, and, by except mixing multiple acrylic resin, also carry out isothermal crystal operation described later (in the operation that makes the resin particle foaming, the acrylic resin particle is kept the specified time under near the temperature its melting point resin, thereby make the operation of acrylic resin recrystallization), can reliably and easily form.

In addition, as previously mentioned, when being that mixing by multiple acrylic resin and isothermal crystal operation are in expanded particle (P1) during formed crystal structure for 2 above endotherm(ic)peaks that high temperature side occurred in main endotherm(ic)peak, this endotherm(ic)peak more than 2 can be divided into the formation expanded particle (P1) that comes from the acrylic resin mixture main endotherm(ic)peak acrylic resin (P1a) composition endotherm(ic)peak and by the formed endotherm(ic)peak of other propylene resin (P1b) composition.

In this endotherm(ic)peak more than 2, the endotherm(ic)peak that comes from acrylic resin (P1a) composition that forms above-mentioned main endotherm(ic)peak, be in the operation of making expanded particle (P1), the formed endotherm(ic)peak of isothermal crystal operation of the acrylic resin (P1a) by forming main endotherm(ic)peak.In addition, the endotherm(ic)peak more than 2 that high temperature side occurred of main endotherm(ic)peak, whether comprise the endotherm(ic)peak that comes from the acrylic resin lower melting propylene resin (P1a) composition that forms main endotherm(ic)peak (below, be sometimes referred to as the high temperature peak) and by the formed endotherm(ic)peak of other high-melting-point acrylic resin (P1b) composition, can confirm by the DSC of following expanded particle.

Use the DSC device 1～3mg expanded particle to be heated to 200 ℃ from normal temperature (general 25 ℃), obtain a DSC curve with the heat-up rate of 2 (℃/minute).Then, after arriving 200 ℃ temperature, with the speed of cooling of 10 (℃/minute) it is cooled to 25 ℃ from 200 ℃ at once, after arriving 25 ℃ temperature, is heated to 200 ℃ with the heat-up rate of 2 (℃/minute) from 25 ℃ at once again, obtain the 2nd DSC curve.

Satisfy condition in 1 the expanded particle (P1), when the endotherm(ic)peak more than 2 that high temperature side occurred in main endotherm(ic)peak, comprise by lower melting propylene resin (P1a) composition that forms main endotherm(ic)peak in the acrylic resin by the formed endotherm(ic)peak of isothermal crystal operation, with by the formed endotherm(ic)peak of other high-melting-point acrylic resin (P1b) composition the time, in passing through a DSC curve of aforesaid method gained, in the endotherm(ic)peak of high temperature side appearance more than 2 of main endotherm(ic)peak.

On the other hand, in the 2nd DSC curve by the aforesaid method gained, the quantity of the existing endotherm(ic)peak of high temperature side of main endotherm(ic)peak reduces (wherein, the endotherm(ic)peak of main endotherm(ic)peak high temperature side has more than 1).So, by an above-mentioned DSC curve and above-mentioned the 2nd DSC curve are compared, can confirm that the main endotherm(ic)peak that occurs more is arranged in 2 above endotherm(ic)peaks of high temperature side in than a DSC curve, at least one endotherm(ic)peak disappears in the 2nd DSC curve.By this relatively, can think that the endotherm(ic)peak that disappears is to come from the endotherm(ic)peak that the lower melting propylene that forms main endotherm(ic)peak is resin (P1a) composition, the endotherm(ic)peak that remains in main endotherm(ic)peak high temperature side is by the formed endotherm(ic)peak of other high-melting-point propylene resin (P1b) composition.For example, in a DSC curve of the expanded particle of Fig. 1, at main endotherm(ic)peak a ₁High temperature side 2 endotherm(ic)peak a have appearred ₂, a ₃Then, in the 2nd DSC curve of this expanded particle of Fig. 2, at the high temperature side of main endotherm(ic)peak 1 endotherm(ic)peak a has only appearred ₃, and endotherm(ic)peak a ₂Disappeared.At this moment, can think the endotherm(ic)peak a that disappears ₂Be to come from the endotherm(ic)peak that the lower melting propylene that forms main endotherm(ic)peak is resin (P1a) composition, endotherm(ic)peak a ₃Be by the formed endotherm(ic)peak of other high-melting-point propylene resin (P1b) composition.

In addition, when obtaining the 2nd DSC curve by DSC, be made as the reason of 10 (℃/minute) from 200 ℃ to 25 ℃ speed of cooling, and when obtaining the 2nd DSC curve, be made as the reason of 2 (℃/minute) from 25 ℃ to 200 ℃ heat-up rates, with when obtaining a DSC curve, the reason that heat-up rate is made as 2 (℃/minute) is identical, be for according to different types of crystal, improve the resolving power of endotherm(ic)peak and measure, and, need make the condition determination unanimity for a DSC curve and the 2nd DSC curve are compared, and crossing when slow when speed of cooling, is not preferred.

In addition, in the aforementioned DSC curve of 1 expanded particle (P1) that satisfies condition, be present in 2 above endotherm(ic)peaks of main endotherm(ic)peak high temperature side, the endotherm(ic)peak heat at aforementioned high temperature peak is preferably the scope of 2～15 (J/g), and 3～12 (J/g) more preferably.By with this endotherm(ic)peak heat regulation to the above-mentioned scope, can make the mechanical properties of expanded particle and the balance of second time of foaming become excellent especially, and consider from the expanded particle formed body aspect that obtains dimensional stability, mechanical properties excellence, also can be used as more excellent expanded particle.In addition, consider, preferably carry out the endotherm(ic)peak heat regulation at above-mentioned high temperature peak by the isothermal crystal operation when making expanded particle described later from the viewpoint of operability and heat regulation stability.

In addition, except using the isothermal crystal method of operating, do not carrying out the isothermal crystal operation, but the method by the different multiple acrylic resin of mixed melting point etc., obtain when main endotherm(ic)peak high temperature side has the expanded particle of crystal structure of 2 above endotherm(ic)peaks, identical with the reason of regulating high temperature peak heat, preferably regulate by the ratio of mixture that changes the different multiple acrylic resin of fusing point, make in 2 above endotherm(ic)peaks that high temperature side occurred of main endotherm(ic)peak, the endotherm(ic)peak heat of the endotherm(ic)peak of lowest temperature side is 2～15 (J/g), and further is the scope of 3～12 (J/g).

In addition, the satisfy condition summit temperature (TmA) of the summit temperature (PTmA) of 1 expanded particle (P1) the main endotherm(ic)peak in the DSC curve of Fig. 1 (a DSC curve of the DSC gained of the heat-up rate by using 2 (℃/minute)) and this expanded particle endotherm(ic)peak in the 2nd DSC curve of Fig. 2 (the 2nd DSC curve of the DSC gained of the heat-up rate by using 2 (℃/minute)) is approximate.

As the preferential progressive type expanded particle of fusion, as mentioned above, 1 the expanded particle of satisfying condition is illustrated, but fuses the particle that preferential progressive type expanded particle is not limited to satisfy above-mentioned condition 1, the expanded particle that satisfies aftermentioned condition 2,3 also is the preferential progressive type expanded particle of fusion.In addition, in 1 the expanded particle of satisfying condition, also exist certainly and satisfy the expanded particle of aftermentioned condition 2 and/or 3 simultaneously.

(1-2) satisfy condition 2 polypropylene-based resin expanded particle (P2)

The condition 2 of polypropylene-based resin expanded particle given to this invention is, polypropylene-based resin expanded particle is 100～140 ℃ low melting point acrylic resin (P2a) and 20～2 weight part fusing points than the mixture of the high high-melting-point acrylic resin (P2b) more than 20 ℃ of this low melting point acrylic resin (P2a) with 80～98 weight part fusing points is substrate resin.Wherein, the gross weight of low melting point acrylic resin (P2a) and high-melting-point acrylic resin (P2b) is 100 weight parts, and their fusing point can adopt the measuring method identical with the melt temperature of aforementioned expanded particle to try to achieve.

By in the expanded particle (P2) of hybrid resin gained in-molded, consider from the viewpoint that reduces the expanded particle fusion temperature, preferably mix the above-mentioned low melting point acrylic resins of 80～98 weight parts (P2a).In addition, this also is preferred aspect the thermotolerance of guaranteeing gained expanded particle formed body.

Consider that from above-mentioned viewpoint the fusing point of low melting point acrylic resin (P2a) is preferably 105～135 ℃, more preferably 105～130 ℃, and be preferably 110～125 ℃ especially, the use level of low melting point acrylic resin (P2a), be preferably 90～98 weight parts, more preferably 92～95 weight parts.

On the other hand, by the expanded particle (P2) of hybrid resin gained in-molded the time, consider from can under the situation of the fusion temperature reduction effect that does not hinder the expanded particle of realizing by cooperation low melting point acrylic resin (P2a), improving expanded particle inflexible viewpoint, preferably mix the above-mentioned high-melting-point acrylic resins of 20～2 weight parts (P2b).

Consider that from above-mentioned viewpoint the melting temperature of low melting point acrylic resin (P2a) and high-melting-point acrylic resin (P2b) is poor, is preferably more than 25 ℃, and more preferably more than 30 ℃, the use level of high-melting-point acrylic resin (P2b) is preferably 10～2 weight parts, more preferably 8～5 weight parts.

This expanded particle (P2) by comprising the substrate resin that has cooperated specified quantitative low melting point acrylic resin (P2a), can reduce the fusion temperature of expanded particle when in-molded.In addition, by comprising the substrate resin that has cooperated specified quantitative high-melting-point acrylic resin (P2b), played the effect that limits expanded particle second time of foaming when in-molded.Therefore, this expanded particle (P2) is the preferential progressive type expanded particle of fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and the fusion character when in-molded between the expanded particle has also improved.In addition, this expanded particle (P2), by when making expanded particle, forming high temperature described later peak, more suitable aspect realization the object of the invention.

Aforementioned low melting point acrylic resin (P2a) is that 100～140 ℃ acrylic resin aspect is considered from obtaining fusing point, is preferably propylene and ethene and/or carbonatoms and is the random copolymers of 4～20 alpha-olefin.

When aforementioned low melting point acrylic resin (P2a) comprises the acrylic resin random copolymers,, can enumerate ethene, 1-butylene, 1-amylene, 1-hexene, 1-octene, 4-methyl isophthalic acid-butylene etc. as the comonomer that carries out copolymerization with propylene.Therefore, as low melting point acrylic resin (P2a), specifically, can enumerate propylene-ethylene random copolymers, propylene-1-butylene random copolymers, propylene-ethylene-1-butylene random copolymers etc.In addition, it is that 4～20 alpha-olefin becomes subdivision that the ethene in the low melting point acrylic resin (P2a) becomes subdivision and/or carbonatoms, considers from fusing point and the viewpoint of keeping physical strength, is preferably 0.01～8 weight %, and 0.05～5 weight % more preferably.

As low melting point acrylic resin (P2a), more preferably using metallocene is polymerizing catalyst, makes propylene and comonomer carry out propylene-ethylene random copolymers, propylene-1-butylene random copolymers, the propylene-ethylene-1-butylene random copolymers of copolymerization gained.

By select using metallocene is that the material of polymerizing catalyst polymerization gained is as low melting point acrylic resin (P2a), (P2b) mixes with the high-melting-point acrylic resin, the fusing point that makes low melting point acrylic resin composition in the hybrid resin with mix in the fusing point of employed this low melting point acrylic resin compare to the low temperature side displacement for example about 5 ℃, therefore can further reduce Heating temperature when in-molded by the expanded particle of this hybrid resin gained.

In addition, using metallocene is the consistency excellence of low melting point acrylic resin (P2a) Yu the high-melting-point acrylic resin (P2b) of polymerizing catalyst gained.

As above-mentioned high-melting-point acrylic resin (P2b), for example, can enumerate segmented copolymer, propylene and ethene that alfon, propylene and ethene and/or carbonatoms are 4～20 alpha-olefin and/or carbonatoms is 4～20 the few random copolymers of content alpha-olefin, this comonomer.

As the preferential progressive type expanded particle of fusion, as mentioned above, though 2 expanded particle is illustrated to satisfying condition, but fuse the particle that preferential progressive type expanded particle is not limited to satisfy above-mentioned condition 2, the expanded particle that satisfies aforementioned condition 1, aftermentioned condition 3 also is the preferential progressive type expanded particle of fusion.In addition, in 2 the expanded particle of satisfying condition, also there is the expanded particle that satisfies aforementioned condition 1 and/or aftermentioned condition 3 simultaneously certainly.

(1-3) satisfy condition 3 polypropylene-based resin expanded particle (P3)

The condition 3 of the polypropylene-based resin expanded particle of defined is among the present invention, in DSC measures, after with 10 ℃/minute heat-up rates polypropylene-based resin expanded particle being heated to 200 ℃ from normal temperature, with 10 ℃/minute cooling rates it is cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with 10 ℃/minute heat-up rate, from 80 ℃ to fusion heat (dH than the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle _L) divided by total endotherm(ic)peak heat (dH _T) heat of gained is than (dH _L/ dH _T) be 0.55～0.80.In addition, at this moment obtain being used to obtain dH _L, dH _TThe step of DSC curve, identical with the measuring method of aforementioned expanded particle melt temperature.

Above-mentioned heat is than (dH _L/ dH _T), the thermal property of expression expanded particle substrate resin, and from can expanded particle (P3) in-molded, reducing the angle of expanded particle fusion temperature, and can under the fusion temperature that does not hinder expanded particle when in-molded reduces the situation of effect, improve expanded particle inflexible angle and consider that heat is than (dH _L/ dH _T) be preferably 0.55～0.80, in addition, by obtaining this heat than (dH _L/ dH _T), can also guarantee the thermotolerance of gained expanded particle formed body.

Consider that from above-mentioned viewpoint heat is than (dH _L/ dH _T) be preferably 0.57～0.80, more preferably 0.50～0.75.In addition, dH _TBe preferably 40～90J/g, 45～75J/g more preferably, and be preferably 45～70J/g especially.

This expanded particle (P3) is by satisfying specific heat than (dH _L/ dH _T), can reduce the fusion temperature of expanded particle when in-molded, simultaneously, played the effect that limits expanded particle second time of foaming when in-molded.Therefore, this expanded particle (P3) is the preferential progressive type expanded particle of fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and the mutual fusion character of expanded particle has also improved when in-molded.In addition, this expanded particle (P3) is more suitable in realizing the object of the invention by forming high temperature described later peak when making expanded particle, becoming.

Constitute the substrate resin of this expanded particle (P3), can enumerate aforementioned homopolymer polypropylene, polypropylene copolymer or be selected from their mixture more than 2 kinds.In these substrate resins, the fusion temperature that never hinders expanded particle when in-molded reduces and improves expanded particle inflexible viewpoint under the situation of effect and consider, the polypropylene copolymer that preferably contains the butylene composition, and special optimization polypropylene-ethylene-butene copolymer.In addition, be preferably 3～15 weight % as the butene content of comonomer composition, more preferably 5～10 weight %.

As the preferential progressive type expanded particle of fusion, as mentioned above, 3 the expanded particle of satisfying condition is illustrated, but fuses the particle that preferential progressive type expanded particle is not limited to satisfy above-mentioned condition 3, the expanded particle that satisfies aforementioned condition 1,2 also is the preferential progressive type expanded particle of fusion.In addition, in 3 the expanded particle of satisfying condition, also there is the expanded particle that satisfies aforementioned condition 1 and/or condition 2 simultaneously certainly.

(1-4) other

(i) melt flow rate (MFR) of expanded particle substrate resin (MFR)

The melt flow rate (MFR) of the substrate resin of used expanded particle (MFR) is 5～60 (g/10 minutes) in the manufacture method of the present invention, more preferably 10～40 (g/10 minutes).

In addition, when the substrate resin of expanded particle is when being made of the material that comprises above-mentioned low melting point acrylic resin and high-melting-point acrylic resin, the MFR of low melting point acrylic resin is preferably 1～100 (g/10 minute), 2～50 (g/10 minutes) more preferably, the MFR of high-melting-point acrylic resin is preferably 0.1～50 (g/10 minute), more preferably 0.2～20 (g/10 minute).

In addition, this MFR is based on the value that the test conditions M (temperature is 230 ℃, loads to be 2.16kg) of JIS K7210 (1999) is measured.

(ii) be added into other component of polymer, the additive of substrate resin

In constituting manufacture method of the present invention in the acrylic resin of used expanded particle substrate resin, can in granulating working procedure etc., in the scope of not damaging action effect of the present invention, cooperate other component of polymer or additive.

As aforesaid other component of polymer, for example, can enumerate high density polyethylene(HDPE), medium-density polyethylene, new LDPE (film grade), straight chain shape new LDPE (film grade), straight chain shape ultra-low density polyethylene, vinyl-vinyl acetate copolymer, ethylene-acrylic acid copolymer, polyethylene-based resins such as ethylene-methacrylic acid copolymer, or polystyrene, polystyrene resins such as styrene-maleic anhydride copolymer, ethylene-propylene is a rubber, ethene-1-butylene rubber, propylene-1-butylene rubber, ethylene-propylene-diene series rubber, synthetic polyisoprene, chloroprene rubber, rubber such as paracril, thermoplastic elastomers such as the hydride of vinylbenzene-diene block copolymer or vinylbenzene-diene block copolymer etc.These resins, rubber or elastomerics can also make up more than 2 kinds and use.When cooperating above-mentioned other component of polymer in acrylic resin, total use level of these other component of polymer preferably is adjusted to below 10 weight parts with respect to the acrylic resin of 100 weight parts.

As aforementioned additive, can enumerate various additives such as bubble conditioning agent, static inhibitor, electroconductibility imparting agent, lubricant, antioxidant, UV light absorber, fire retardant, metal passivator, pigment, dyestuff, crystallization nucleating agent or inorganic filling material, and can as required they be engaged in the acrylic resin that constitutes expanded particle.The use level of these various additives, different and different according to adding purpose, but, be preferably below 25 weight parts with respect to 100 weight part substrate resins, more preferably below 15 weight parts, more preferably below 8 weight parts, and most preferably be below 5 weight parts.

In addition, constitute the substrate resin of expanded particle, consider, be preferably no cross-linked polypropylene resin from viewpoints such as reproducibility, expanded particle productivitys.

The (iii) granulation of resin particle

Be suitable for making the granulation of resin particle of the size of expanded particle, can adopt the substrate resin that uses forcing machine will comprise aforementioned acrylic resin to extrude and be band shape, again it is cut to the line cutting mode (ス ト ラ Application De カ Star ト mode) of suitable length or known in the past prilling process such as cutting mode under water.

When the substrate resin of used expanded particle comprises the hybrid resin of multiple acrylic resin in constituting the present invention, use the mixing at least 2 kinds of resins of mixing roll, and mixing to both mixing fully and evenly.

Above-mentioned is fully mixing, for example, be preferably the high forcing machines of mixing property such as using biaxial extruder and carry out mixing method, or adopt the manufacturing process of the hungry forming method (Hunger Hungry that is put down in writing in the TOHKEMY 2006-69143 communique), use forcing machine to carry out mixing method.

Used expanded particle among the present invention, its each weight in average is preferably 0.01～10.0mg usually, and is preferably 0.1～5.0mg especially, the adjusting of its weight in average, the above-mentioned granulating working procedure of resin particle that can be by obtaining being used to form expanded particle is regulated.

(1-5) manufacturing of polypropylene-based resin expanded particle

Used expanded particle in the manufacture method of the present invention, can use Japanese Patent Publication 49-2183 communique, Japanese Patent Publication 56-1344 communique, the known foaming method that Japanese Patent Publication 62-61227 communique etc. is put down in writing, promptly, in encloses container, to be dispersed in the dispersion medium such as water by acrylic resin particle and the whipping agent that preceding method etc. carries out the granulation gained, heating under agitation, make the resin particle remollescent simultaneously, pneumatogen is infiltrated up in the resin particle, then under the temperature more than the softening temperature of resin particle, resin particle is discharged in the area of low pressure low in the pressure ratio container (being generally atmospheric pressure region), makes its foaming.In addition, in order to obtain expanded particle, and with the content in the encloses container when encloses container is discharged into the area of low pressure, consider from the homogenizing viewpoint of the apparent density of gained expanded particle, preferably by used pneumatogen or inorganic gass such as nitrogen, air to applying back pressure in the encloses container, make pressure in this container can be sharply release content with descending.When making expanded particle, as dispersion resin dispersion of particles medium, be not limited to above-mentioned water, so long as do not dissolve the medium of resin particle, can use.As the dispersion medium beyond the water, for example, can enumerate ethylene glycol, glycerol, methyl alcohol, ethanol etc., but make water usually.

In aforesaid method, for resin particle is dispersed in the dispersion medium, preferably as required, dispersion agents such as slightly water-soluble inorganic substance such as dispersed alumina, calcium phosphate, magnesium pyrophosphate, zinc oxide, kaolin in dispersion medium, anionic surfactants such as Sodium dodecylbenzene sulfonate, alkyl sodium sulfonate etc. disperse auxiliary agent.When making expanded particle, the amount of adding the dispersion agent in the dispersion medium to, the ratio (weight of the weight/dispersion agent of resin particle) in the weight and the dispersion agent weight of resin particle is preferably 20～2000, and more preferably 30～1000.In addition, the ratio of the weight of dispersion agent and dispersing auxiliary weight (weight of the weight/dispersing auxiliary of dispersion agent) is preferably 1～500, and more preferably 5～100.

The mean air bubble diameter of used expanded particle among the present invention is generally 30～500 μ m, and is preferably 50～350 μ m.Expanded particle with the mean air bubble diameter in the above-mentioned scope is considered from the strength relationship of bubble chamber film, and when expanded particle described later in-molded, the bubble that does not constitute expanded particle produces the risk of broken bubble, has demonstrated good in-molded property.

The mean air bubble diameter of aforementioned expanded particle can be based on using microscope photographing that expanded particle is cut into the enlarged photograph of the bubble section of general 2 gained such as branch such as grade, and obtain by following operation.In the enlarged photograph of above-mentioned bubble section, from central division on 8 directions on expanded particle surface, with radial draw 4 from the surfaces of expanded particle the approximate centre by bubble section up to another surperficial straight line.Then, obtain the total number of bubbles that intersects with aforementioned 4 straight lines: N (individual).Then, each arrives the summation of another surperficial line segment length: L (μ m) divided by total number of bubbles: N (individual) (L/N) since the expanded particle surface with aforementioned 4 straight lines, and the value that will obtain is as the mean air bubble diameter of expanded particle.

In addition, because aforementioned mean air bubble diameter, become big along with the high MFRization of substrate resin, the raising of blowing temperature, the minimizing of whipping agent and the minimizing of bubble conditioning agent etc., therefore can pass through suitably to regulate the changing factor of these mean air bubble diameters, and obtain the expanded particle of purpose mean air bubble diameter.

In addition, control method as the mean air bubble diameter of aforementioned expanded particle, mainly be when being used to obtain the resin particle of expanded particle in manufacturing, being the ratio of 0.01～5 weight part with respect to 100 weight part substrate resins, in substrate resin, cooperate talcum, aluminium hydroxide, silicon-dioxide, zeolite, inorganicss such as borax carry out as the bubble conditioning agent, but the blowing temperature when making because of above-mentioned expanded particle owing to this mean air bubble diameter or the kind of whipping agent and usage quantity etc. change, therefore, in order to obtain having the expanded particle of purpose mean air bubble diameter, need carry out preliminary experiment and impose a condition.

Used 1～3 at least one the expanded particle that satisfies condition preferably has aforesaid high temperature peak among the present invention.

Expanded particle with high temperature peak can suitably obtain by following method, promptly, in aforementioned known foaming method, in encloses container, resin particle is dispersed in when heating in the dispersion medium, be not warming up to resin particle the fusion end temp (below, be also referred to as Te) more than, but than the fusing point of resin particle (below, being also referred to as Tm) low 15 ℃ temperature is above and less than stopping heating under the arbitrary temp Ta in the scope of Te, and under this temperature T a, keep time enough, the preferred maintenance about 10～60 minutes, then, be adjusted to (Tm-5 ℃)～the arbitrary temp Tb of the scope of (Te+5 ℃), and under this temperature, resin particle be discharged in the area of low pressure from container, make the method for its foaming.In addition, in order to form the high temperature peak, and remain on more than above-mentioned (Tm-15 ℃) and less than the process in the scope of Te, can in this temperature range, set a plurality of stages, in addition also can be in this temperature range through time enough (slow and sequentially (continuously)) (the slowly and sequentially (continuously)) that slowly heat up.

The formation at the above-mentioned high temperature peak of expanded particle, and the size of the endotherm(ic)peak heat at high temperature peak, mainly exist with ... when making expanded particle for the said temperature Ta of resin particle and the hold-time under this temperature T a, said temperature Tb, and the heat-up rate in the scope of (Tm-15 ℃)～(Te+5 ℃).

The heat at the above-mentioned high temperature peak of expanded particle, when (1) temperature T a or Tb low more in above-mentioned each temperature range, (2) more than (Tm-15 ℃) and less than the hold-time in the scope of Ta long more, and (3) are more than (Tm-15 ℃) and slow more less than the heat-up rate in the scope of Te, then big more.In addition, above-mentioned heat-up rate is selected in the scope of 0.5～5 (℃/minute) usually.On the other hand, the heat at the above-mentioned high temperature peak of expanded particle, when temperature T a or Tb high more in above-mentioned each temperature range, more than (Tm-15 ℃) and less than the hold-time in the scope of Te short more, and more than (Tm-15 ℃) and fast more less than the heat-up rate in the scope of Te, heat-up rate is slow more, then more little in the scope of Te～(Te+5 ℃).Consider these aspects,, then can know creating conditions of the expanded particle that demonstrates desirable high temperature peak heat if carry out preliminary experiment repeatedly.In addition, the temperature range at above-mentioned formation high temperature peak, being to use inorganic is the suitable temperature range of pneumatogen during as whipping agent.Therefore, when whipping agent changed to the organic system pneumatogen, according to its kind or usage quantity, its suitable temperature range was respectively to about 0～30 ℃ of low temperature sidesway with the said temperature scope.

As whipping agent used in the aforesaid method, can use the organic system pneumatogen or inorganic be pneumatogen, or their mixture etc.As the organic system pneumatogen, can enumerate aliphatic hydrocarbons such as propane, butane, hexane, pentane, heptane, ester ring type such as tetramethylene, hexanaphthene hydrocarbon, halohydrocarbon such as methyl chloride, monochloroethane, methylene dichloride, dialkyl ethers such as dme, diethyl ether, methyl ethyl ether etc., and they can use a kind or will be more than 2 kinds mix and use.In addition, as inorganic be pneumatogen, can enumerate nitrogen, carbonic acid gas, argon, air, water etc., and they can use a kind or will be more than 2 kinds mix and use.With the organic system pneumatogen and inorganic be physical foaming agent and mixing when using, can from above-mentioned organic system pneumatogen and inorganic be to select arbitrarily the pneumatogen and be used in combination.In addition, be used in combination organic system pneumatogen and inorganic when being pneumatogen, containing above inorganic of at least 30 weight % in the preferred whipping agent is pneumatogen.

The apparent density of used polypropylene-based resin expanded particle among the present invention can be by above-mentioned whipping agent to the infiltration amount of resin particle and easily regulate.

In the above-mentioned whipping agent, particularly consider that from the viewpoint of environment protection preferred inorganic is pneumatogen, wherein preferred nitrogen, air, carbonic acid gas, water.In addition, when obtaining expanded particle, when in encloses container, making water as dispersion medium with resin particle, by carrying out mixing with this resin particle absorbent resin etc. and use, can with as the water of dispersion medium effectively as whipping agent.

The usage quantity of whipping agent is considered the apparent density of purpose expanded particle, the kind of substrate resin or the kind of whipping agent etc. and is determined.Usually, preferably supply with pneumatogen in container, making the pressure of space segment in the encloses container is 0.05～10MPa (G), and further is 1～8MPa (G).

Use preceding method, the resin particle that will contain the soft state of whipping agent is discharged into the polypropylene-based resin expanded particle of gained in the area of low pressure from encloses container, after the release through common health operation under atmospheric pressure region of carrying out (Raising give birth to engineering), form the polypropylene-based resin expanded particle of in-molded usefulness.

(2) manufacture method of polypropylene-based resin expanded particle formed body

As manufacture method of the present invention, for example can adopt: (1) is filled in the expanded particle of aforementioned in-molded usefulness can heating and cooling and can switch, airtight known in the past expanded particle is in-molded with in the die cavity of mould, (2) then, by supply with Saturated water vapor pressure in mould is 0.05～0.30MPa (G), be preferably the water vapour of 0.08～0.25MPa (G), the foamable particle, expanded particle is expanded, and fusion each other, (3) then, the expanded particle formed body of cooling gained, and with its in-molded method of intermittent type of taking out in the die cavity (for example, special fair 4-46217 communique of Japan, the forming method of being put down in writing in the special fair 6-49795 communique of Japan etc.).

In addition, can be as required, the expanded particle of aforementioned in-molded usefulness joined in advance be used for the encloses container that the expanded particle to aforementioned in-molded usefulness pressurizes, regulate by gas under pressures such as air, making the pressure in the encloses container is 0.01～1MPa (G), improves the pressure treatment of the pressure in the expanded particle, the pressure in the expanded particle is adjusted to 0.01～0.2MPa (G) after, fill it into aforementioned in-molded using in the die cavity of mould, carry out in-molded.

In addition, method as the heating of the water vapour in the above-mentioned in-molded method, can adopt side heating (side adds Hot), an opposite side (a contrary side adds Hot) heating, the known method in the past that the heating means appropriate combination is used such as is heated simultaneously in both sides, and especially preferably according to the preparation heating, in side heating, in the method for opposite side heating, the heated in sequence expanded particle that heats simultaneously in both sides.The Saturated water vapor pressure of above-mentioned 0.05～0.30MPa (G) when in addition, expanded particle is in-molded is in order to heat the maximum value of the Saturated water vapor pressure that is supplied to the water vapour in the mould by heat in a side, heat simultaneously in opposite side heating, in both sides etc. in above-mentioned in-molded operation.

In addition, the expanded particle formed body can also be made by the following method, promptly, after as required the pressure in the expanded particle being adjusted to 0.01～0.2MPa (G), by the travelling belt that moves continuously up and down in path with heating region and cooled region, expanded particle is supplied to continuously in the mould of formation, and when it passes through heating region, supplying with Saturated water vapor pressure in mould is 0.05～0.30MPa (G), be preferably the water vapour of 0.08～0.25MPa (G), the foamable particle, expanded particle is expanded, and fusion each other, then, it is cooled off by cooled region, then, the expanded particle formed body of gained is taken out in die cavity, and be cut to the in-molded method of continous way (for example, the Japanese kokai publication hei 9-104026 communique of suitable length successively, the forming method of being put down in writing in Japanese kokai publication hei 9-104027 communique and the Japanese kokai publication hei 10-180888 communique etc.).

In manufacture method of the present invention, use in expanded particle in-molded, by using water vapour to heat, the surface that at first forms expanded particle each other can the interfused state, then expanded particle self is softening, formation can second time of foaming state, form all excellent good expanded particle formed body of the mutual fusion character of outward appearance and expanded particle thus.In addition, even produced heating inequality more or less when this is in-molded, but because the mold temperature wide ranges also can form good expanded particle formed body.

In addition, when making highdensity expanded particle formed body, when in the past polypropylene-based resin expanded particle in-molded, can make apparent density is the above expanded particles of 70 (g/L), and the rate of compression during if not filling-foam particle in mould cavity be more than 20% high state, and use the high water vapor pressure that surpasses 0.30MPa (G) to carry out the in-molded method of saturated steam heating, then be difficult to obtain good expanded particle formed body.But, manufacturing method according to the invention, has following characteristics, promptly need not adopt saturated steam heating, the in-molded method under high compression rate of this use high water vapor pressure, perhaps with in the past compare, even do not improve the internal pressure that is filled to the expanded particle in the mould, can obtain good low range expanded particle formed body yet.

Therefore, the manufacture method of expanded particle formed body of the present invention is characterised in that the rate of compression that this expanded particle is filled in the mould is 0～15% when in-molded.

Rate of compression when above-mentioned expanded particle is filled to mould cavity can and be filled to the stacking volume of the expanded particle of mould by mould cavity internal volume: MV (L): BV (L), obtain according to the formula of (BV-MV)/MV * 100.In addition, be filled to that the stacking volume of the expanded particle of mould: BV is following to be obtained: be that expanded particle is encased in the empty graduated cylinder, and with the weight (g) of the expanded particle that is encased in this graduated cylinder divided by the shown volume of cylinder scale (L), obtain the tap density of expanded particle, again the known expanded particle of tap density is filled in the mould, calculates divided by the tap density of this expanded particle with the weight (g) that is filled into this expanded particle in the mould.

Expanded particle formed body by manufacture method gained of the present invention, as previously mentioned, can be 100～720 (g/L) by using density, and satisfy at least one expanded particle of aforementioned condition 1～3, and the rate of compression will fill this expanded particle in mould the time is adjusted to 0～15%, carries out in-molded and obtains.In addition, consider that from the viewpoint of mutual fusion character of the expanded particle of expanded particle formed body and outward appearance above-mentioned rate of compression is preferably 3～15%, and more preferably 5～13%.

(3) polypropylene-based resin expanded particle formed body

Polypropylene-based resin expanded particle formed body of the present invention, be polypropylene-based resin expanded particle to be filled into carry out the expanded particle formed body that hot briquetting forms in the mould, it is characterized in that, the density of this expanded particle formed body is 60～450g/L, in test according to the non-notch test method of the charpy impact intensity of JIS K7111-1 (2006), make the test film fracture, by the material damage in all expanded particles on the gained surface of fracture the fusion rate of the polypropylene-based resin expanded particle obtained of the ratio of expanded particle be more than 50%, the density of the density D s of the skin section of this expanded particle formed body and the internal density Dc of this expanded particle formed body is 1～2 than Ds/Dc

The polypropylene-based resin expanded particle that forms this expanded particle formed body satisfies at least one of aforementioned condition 1～condition 3.

Expanded particle formed body of the present invention is the expanded particle formed body that can obtain by manufacture method of the present invention.

Expanded particle formed body of the present invention, its expanded particle is closely fusion each other, and in the test that embodiment described in detail carries out according to the non-notch test method of the charpy impact intensity of JIS K7111-1 (2006), make the test film fracture, by material damage in all expanded particles on the gained surface of fracture the fusion rate of the expanded particle obtained of the ratio of expanded particle be more than 50%, be preferably more than 70%, have mechanical properties such as good compression intensity.In addition, this expanded particle formed body is lip-deep concavo-convex few, level and smooth, and dimensional stability is also excellent.

In addition, consider that from purposes such as desirable physical strength, resiliency, light weights the density of this expanded particle formed body is 60～450 (g/L), and is preferably 90～300 (g/L).

In addition, the density of expanded particle formed body (g/L) can be obtained divided by the volume of being obtained by the physical dimension of this expanded particle formed body (L) by the weight (g) of expanded particle formed body.

Further, the expanded particle formed body is characterised in that, the skin section density (Ds) of this expanded particle formed body (g/L) and internal density (Dc) density (g/L) of this expanded particle formed body be 1～2 than (Ds/Dc).The density distribution of this expression expanded particle formed body is compared with the past to be uniform.Low range expanded particle formed body in the past, owing to be subjected to the restriction of the manufacture method of expanded particle formed body, the skin section density of expanded particle formed body just looks like to be that low-density foaming layer is clipped in the multilayered structure in the highdensity foaming layer far above internal density.Therefore, expanded particle formed body in the past, the density of its skin section is far above the ensemble average density of this expanded particle formed body, and its internal density is far below the ensemble average density of this expanded particle formed body.

The compressive strength of this expanded particle formed body in the past because when this expanded particle formed body of compression, the much lower inside foam of density at first is out of shape, therefore is difficult to obtain the quite high compression rerum natura of global density.On the contrary, expanded particle formed body by manufacture method gained of the present invention, as previously mentioned, the density distribution of expanded particle formed body is compared with the past to be uniform, therefore can show the high compression rerum natura that is equivalent to this density, simultaneously, the stability of mechanical properties is also excellent, and can improve the isochronous rerum natura offset issue of secondary processing.Consider that from above-mentioned viewpoint the above-mentioned of expanded particle formed body is preferably 1.1～1.7 than (Ds/Dc), more preferably 1.1～1.5, and be preferably 1.2～1.4 especially.In addition, the ratio (Ds/Dc) of expanded particle formed body is for the skin section and the inside (Li face on surface) skin section, all satisfy above-mentioned relation than (Ds/Dc).

In addition, the skin section density (Ds) of expanded particle formed body (g/L) and internal density (Dc) measuring method (g/L) as described below.

The skin section of expanded particle formed body comprises the surface that is referred to as expanded particle formed body epidermis side, and is the surface from the expanded particle formed body, on thickness direction to the dark part of 5mm.Therefore, the skin section density (Ds) of this expanded particle formed body, can be by cutting out skin section (as concrete example from the expanded particle formed body, cut out the surface that comprises the expanded particle formed body, and be surface from the expanded particle formed body, on thickness direction,, form the rectangular parallelepiped sample of long 50mm, wide 50mm, thick 5mm to the dark part of 5mm), and obtain divided by the volume (L) of this sample with the sample weight that cuts out (g).

On the other hand, the inside of expanded particle formed body is the centre portions of expanded particle formed body, and it does not comprise the surface of expanded particle formed body, and is the part that is respectively 5mm from the central authorities of expanded particle formed body thickness direction to surface and the inside.Therefore, the internal density of this expanded particle formed body (Dc), can be by cutting out inside (as concrete example from the expanded particle formed body, cut out the surface that does not comprise the expanded particle formed body, and be the part that is respectively 5mm from the central authorities of expanded particle formed body thickness direction to surface and the inside, form the rectangular parallelepiped sample of long 50mm, wide 50mm, thick 10mm), and obtain divided by the volume (L) of this sample with the sample weight that cuts out (g).

In addition, the expanded particle formed body is preferably below 40% based on the continuous air bubbles rate that order C obtained of ASTM-D2856-70, and more preferably below 30%, and most preferably is below 25%.The expanded particle formed body that the continuous air bubbles rate is more little, physical strength is excellent more.

Form the expanded particle of expanded particle formed body of the present invention, be characterised in that it is at least one the preferential progressive type expanded particle of fusion that satisfies aforementioned condition 1～3.The expanded particle that forms the expanded particle formed body is by satisfying this condition, when expanded particle in-molded, fully arrive each interior corner of mould owing to add the hot steam, thereby can the even heating expanded particle, in addition, the mold temperature scope of expanded particle is expanded to low temperature side, even therefore when in-molded, the Heating temperature of expanded particle has produced difference more or less in mould, also can realize the good fusion that expanded particle is mutual, for these reasons, the expanded particle formed body of low expansion ratio was compared in the past, formed fusion rate height especially, the density difference of expanded particle formed body skin section and inside is little, and the also excellent expanded particle formed body of compression rerum natura.

In addition, for the aforementioned condition 1～3 of the expanded particle that forms expanded particle formed body of the present invention, this expanded particle changes minimum in the rerum natura of carrying out in-molded front and back.

Expanded particle formed body by manufacture method gained of the present invention, have characteristics such as resiliency, dimensional stability, rigidity, light weight, wrapping material, material of construction or automobile be can be widely used in impact absorbing material etc., and wrapping material, the automobile thin wall component of accurate electrical and electronic parts are particularly suitable for.

Embodiment

Below, by embodiments of the invention, comparative example the present invention is specifically described.

Used resin and proterties thereof in embodiment, comparative example shown in the following table 1.

[embodiment 1～6, and comparative example 1,2]

(1) manufacturing of polypropylene-based resin expanded particle

Use the single shaft forcing machine of internal diameter as 65mm, with the proportioning shown in the table 2 with the described acrylic resin of table 1 with the zinc borate of 500 ppm by weight in forcing machine melting mixing (but in embodiment 1～4, use this forcing machine to carry out melting mixing) with following hungry operating condition, mixing thing is extruded into pencil from the nozzle aperture that is installed in the forcing machine front end, in tank, cool off, become weight to be approximately 1mg this tractotomy again, drying obtains resin particle.In addition, above-mentioned hungry operating condition, be by aforementioned hungry forming method, fusing point, resin that melt viscosity difference is big is mixing to the method for good distribution each other, and be that feed device by the capacity formula carries out feed when regulating the supply of resin, make with respect to the raw material supplying portion that is full of forcing machine with the material resin particle, the resin discharge-amount of forcing machine when being full of routine in the forcing machine and being full of operating condition with resin, below when the resin discharge-amount under the identical screw speed is being full of running, the method for extruding.In embodiment 1～4, the discharge-amount (kg/ hour) during hungry the running is 70% with respect to being full of when turning round.

The resin particle of the above-mentioned gained of 1kg and 3L (liter) are joined in the 5L encloses container that has stirrer together as the water of dispersion medium, in dispersion medium, add the kaolin (English name: Kaolin) of 0.3 weight part again as dispersion agent, 0.004 weight part is as the sodium alkyl benzene sulfonate (trade(brand)name: ネ オ ゲ Application (English name: Neogen) S-20 of tensio-active agent, the first industrial drugmaker makes) (wherein, described 0.004 weight part is the sodium alkyl benzene sulfonate amount among the ネ オ ゲ Application S-20), and 0.01 weight part Tai-Ace S 150, and in encloses container, be pressed into pressurized air as whipping agent to the pressure shown in the table 2, under agitation be warming up to the blowing temperature shown in the table 2, and under uniform temp, kept 15 minutes, regulate the endotherm(ic)peak heat at high temperature peak, then content is disposed under the normal atmosphere, obtains having the expanded particle of apparent density shown in the table 2.In addition, above-mentioned weight part is the weight part with respect to 100 parts by weight resin particles.The proterties of gained expanded particle is shown in table 2 in the lump.

(2) manufacturing of expanded particle formed body

The flat board that the expanded particle of above-mentioned gained is filled in long 250mm, wide 200mm, thick 50mm is with in the mould, by the water vapour heating, carries out in-moldedly under the in-molded condition shown in the table 3, obtains tabular expanded particle formed body.With the health 12 hours in 80 ℃ baking oven of the expanded particle molding that obtains, obtain the polypropylene-based resin expanded particle molding.The proterties of gained expanded particle formed body is shown in table 3 in the lump.

(3) evaluation method of expanded particle and expanded particle formed body

The evaluation method of expanded particle in the table 2,3 and expanded particle formed body is as follows.

(3-1) evaluation method of expanded particle in the table 2 and expanded particle formed body

(i) apparent density of expanded particle and apparent density are than (ρ _R) mensuration

The apparent density of expanded particle and apparent density are than (ρ _R) mensuration, adopt the method for being put down in writing in aforementioned " (1) polypropylene-based resin expanded particle ".

The (ii) mensuration of total endotherm(ic)peak heat of expanded particle, main endotherm(ic)peak heat and high temperature side endotherm(ic)peak heat

The method of being put down in writing during that the mensuration of total endotherm(ic)peak heat of expanded particle, main endotherm(ic)peak heat and high temperature side endotherm(ic)peak heat adopts is aforementioned " (1-1) satisfy condition 1 polypropylene-based resin expanded particle ".

The (iii) total endotherm(ic)peak heat (dH among the 2nd DSC _T) and fusion heat (dH _L) mensuration

Total endotherm(ic)peak heat (dH among the 2nd DSC _T) and fusion heat (dH _L) mensuration, adopt the method for being put down in writing in aforementioned " (1-3) satisfy condition 3 polypropylene-based resin expanded particle ".

(3-2) evaluation method of expanded particle in the table 3 and expanded particle formed body

(i) mensuration of the fusion pressure (PF) of expanded particle

DSC curve based on expanded particle, the lower limit of the temperature of prediction expanded particle melt surface, and the steam of the Saturated water vapor pressure by being equivalent to this lower limit temperature carries out the in-molded of expanded particle, the expanded particle formed body of gained is carried out the evaluation of the mutual fusion character of following expanded particle, and the fusion rate of confirming the expanded particle formed body is less than 50%.Then, except the Saturated water vapor pressure of steam is set the high 0.01MPa, similarly carry out the evaluation of above-mentioned fusion character.Carry out successively setting the Saturated water vapor pressure of steam to such an extent that high 0.01MPa estimates the operation of fusion character, fusion rate until the expanded particle formed body reaches more than 50%, and should the fusion rate reaches 50% Saturated water vapor pressure (this fusion rate reaches the minimum Saturated water vapor pressure more than 50%) when above for the first time as fusion pressure.In addition, the mould of above-mentioned in-molded use is the rectangular shape of molding space for long 250mm, wide 250mm, thick 20mm, and the rate of compression when being filled into expanded particle in this mould is set at 10%.Be noted that use is that 23 ℃, relative humidity are to place the expanded particle that carried out status adjustment in 48 hours under the condition under 50% the normal atmosphere at temperature, as expanded particle used in the said determination.In addition, the fusion rate of above-mentioned expanded particle formed body is the value of being obtained by the aftermentioned method.

The (ii) mensuration of the second time of foaming pressure (PA) of expanded particle

DSC curve based on expanded particle, the lower limit of the temperature of prediction expanded particle second time of foaming, and the steam of the Saturated water vapor pressure by being equivalent to this lower limit temperature, be 5L (liter) and have in the encloses container of pressure regulator valve at volume, be about 100cm to what add in stacking volume ³Expanded particle heated for 10 seconds, and measure the apparent density of the expanded particle after the heating of gained.The density ratio of the apparent density (g/L) before the apparent density (g/L) of the expanded particle after the heating of obtaining as above to be measured and this expanded particle heating, the value of confirming [apparent density (g/L) before the heating]/[apparent density after the heating (g/L)] is less than 1.5.Then, except the Saturated water vapor pressure of steam is set the high 0.01MPa, similarly carry out the evaluation of above-mentioned second time of foaming.Carry out successively setting the Saturated water vapor pressure of steam to such an extent that high 0.01MPa estimates the operation of second time of foaming, reach more than 1.5 until the density of expanded particle value, and the value of this density ratio is reached 1.5 Saturated water vapor pressures (value of this density ratio reaches the minimum Saturated water vapor pressure more than 1.5) when above for the first time as second time of foaming pressure than { [apparent density (g/L) before the heating]/[apparent density after the heating (g/L)] }.Be noted that use is that 23 ℃, relative humidity are to place the expanded particle that carried out status adjustment in 48 hours, used expanded particle in measuring as above-mentioned apparent density under the condition under 50% the normal atmosphere at temperature.

The (iii) mensuration of 50% stress under compression

(iii-1) have 50% stress under compression (A) of the test film of epidermis

50% stress under compression (A) that has the test film of epidermis, it is the test film that has epidermis that cuts out long 50mm, wide 50mm, thick (total thickness of formed body) 50mm from the expanded particle formed body, and according to JIS K6767 (1999), with 10mm/ minute compression speed compression testing sheet on thickness direction, carry out compression testing, obtain 50% stress under compression (A) of expanded particle formed body.

(iii-2) 50% stress under compression (B) of the test film of no epidermis

50% stress under compression (B) of the test film of no epidermis, be from the expanded particle formed body, to cut out long 50mm, wide 50mm, the cubes of thick (total thickness of formed body) 50mm, further, in order to cut existing epidermis on the top and bottom of expanded particle formed body thickness direction, thickness from the top and bottom of thickness direction with the 12.5mm that respectively does for oneself cuts epidermis, form long 50mm, wide 50mm, the test film of the no epidermis of thick 25mm, and according to JIS K6767 (1999), with 10mm/ minute compression speed compression testing sheet on thickness direction, carry out compression testing, obtain 50% stress under compression (B) of expanded particle formed body.

The (iv) density measurement of expanded particle formed body

The density of expanded particle formed body is obtained divided by volume (L) by the weight (g) with this expanded particle formed body.

(the v) density D of the skin section of expanded particle formed body _SWith internal density D _CDensity than (D _S/ D _C) mensuration

Density is than (D _S/ D _C) mensuration, adopt the method for being put down in writing in aforementioned " (3) polypropylene-based resin expanded particle formed body ".

(the vi) mensuration of test film density

(vi-1) have the test film density of epidermis

The test film density that has epidermis is the test film that has epidermis that cuts out long 50mm, wide 50mm, thick (total thickness of formed body) 50mm from the expanded particle formed body, and obtains divided by the volume (L) of this test film with test film weight (g).

(vi-2) the test film density of no epidermis

The test film density of no epidermis, it is the cubes that cuts out long 50mm, wide 50mm, thick (total thickness of formed body) 50mm from the expanded particle formed body, further, in order to cut existing epidermis on the top and bottom of expanded particle formed body thickness direction, thickness from the top and bottom of thickness direction with the 12.5mm that respectively does for oneself cuts epidermis, form the test film of the no epidermis of long 50mm, wide 50mm, thick 25mm, and obtain divided by the volume (L) of this test film with test film weight (g).

(vii) fusion character

The expanded particle fusion rate of expanded particle formed body, except the test film size is changed to vertical 10mm, laterally 10mm, length are the 80mm, non-notch test method according to the charpy impact intensity of JIS K7111-1 (2006) is tested, make test film fracture, and by material damage on the surface of fracture the ratio of expanded particle obtain.In addition, when test film did not rupture, the fusion rate was 100%.

Fusion rate=material damage expanded particle number (individual)/section (vertically 10mm, laterally 10mm) on total expanded particle number (individual) * 100

According to the fusion rate of as above being obtained, estimate according to following benchmark.

◎: the fusion rate is more than 70%

Zero: the fusion rate is more than 50% and less than 70%

△: the fusion rate is more than 30% and less than 50%

*: the fusion rate is less than 30%

(viii) outward appearance

By the surface of visual inspection expanded particle formed body, and according to following benchmark evaluation outward appearance.

Zero: on the surface of expanded particle formed body, almost do not have particle gap or concavo-convex, demonstrate the surface of good state.

△: on the surface of expanded particle formed body, can know and confirm particle gap and/or concavo-convex.

*: particle gap and/or concavo-convex remarkable on the surface of expanded particle formed body.

(4) evaluation of expanded particle and expanded particle formed body

As shown in table 3, though the polypropylene-based resin expanded particle formed body in the embodiment of the invention is the expanded particle formed body of low expansion ratio, the fusion character excellence that expanded particle is mutual, the outward appearance of this expanded particle formed body is also good.In addition, the skin section of expanded particle formed body and inner density ratio are below 2, compare with the expanded particle formed body in the past shown in the comparative example, and this density ratio approaches 1, and the density uniformity of expanded particle formed body improves.

In the table 3 based on the polypropylene-based resin expanded particle formed body of the comparative example of prior art, fusion character that its expanded particle is mutual and outward appearance deficiency, perhaps, even fusion character and outward appearance are in allowed limits, the density uniformity of the skin section of expanded particle formed body and inside is also not enough.

In addition, compressive strength about the expanded particle formed body, between the equal densities formed body of the comparative example 1 by the embodiment of the invention 3,4 and prior art in the comparison aspect 50% stress under compression of table 3, though substrate resin is variant as can be known, but expanded particle formed body of the present invention, its compressive strength ratio formed body excellence in the past.In addition, for the value of the compression rerum natura ratio of table 3, compare expanded particle formed body of the present invention as can be known with comparative example 1,2 by embodiment 1～6, the compressive strength difference of the skin section of its expanded particle formed body and inside is littler than in the past, and the excellent in uniformity of compressive strength.

As shown in Table 3, though the polypropylene-based resin expanded particle shown in the embodiment of the invention of table 2, vapor pressure when it is in-molded is low, and (particularly embodiment 1, though its vapor pressure is extremely low), also can obtain the mutual fusion character and the good expanded particle formed body of outward appearance of expanded particle of expanded particle formed body.

Claims (2)

1. polypropylene-based resin expanded particle formed body, it is polypropylene-based resin expanded particle to be filled in carry out the expanded particle formed body that hot briquetting forms in the mould, it is characterized in that,

The density of this expanded particle formed body is 60g/L～450g/L, and the fusion rate of polypropylene-based resin expanded particle is more than 50%, and the skin section density of this expanded particle formed body is 1～2 divided by the density ratio of the internal density gained of this formed body,

The polypropylene-based resin expanded particle that forms this expanded particle formed body satisfies at least one in following condition 1～condition 3,

Condition 1: have following crystal structure, promptly, in heat flux differential scanning calorimetry, with 2 ℃/minute heat-up rates polypropylene-based resin expanded particle is heated to the DSC curve of 200 ℃ of gained from normal temperature, appearance is 100 ℃～140 ℃ a main endotherm(ic)peak with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at the endotherm(ic)peak more than 2 of this main endotherm(ic)peak high temperature side;

Condition 2: polypropylene-based resin expanded particle is 100 ℃～140 ℃ low melting point acrylic resin and 20～2 weight part fusing points than the mixture of the high high-melting-point acrylic resin more than 20 ℃ of this low melting point acrylic resin as substrate resin with 80～98 weight part fusing points;

Condition 3: in heat flux differential scanning calorimetry, after with 10 ℃/minute heat-up rates polypropylene-based resin expanded particle being heated to 200 ℃ from normal temperature, with 10 ℃/minute cooling rates it is cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with 10 ℃/minute heat-up rate, from 80 ℃ to being 0.55～0.80 divided by the heat ratio of total endotherm(ic)peak heat gained than the fusion heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle.

2. the manufacture method of a polypropylene-based resin expanded particle formed body, it is the manufacture method that polypropylene-based resin expanded particle is filled in the expanded particle formed body that carries out hot briquetting in the mould, it is characterized in that,

The apparent density of this polypropylene-based resin expanded particle is 100g/L～720g/L, and simultaneously, it satisfies following condition 1～condition 3 at least one, and the rate of compression of this polypropylene-based resin expanded particle when being filled in the mould be 0～15%,

Condition 1: have following crystal structure, promptly, in heat flux differential scanning calorimetry, with 2 ℃/minute heat-up rates polypropylene-based resin expanded particle is heated to the DSC curve of 200 ℃ of gained from normal temperature, having occurred with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak is 100 ℃～140 ℃ main endotherm(ic)peak, and the crystal structure that is positioned at the endotherm(ic)peak more than 2 of this main endotherm(ic)peak high temperature side;

Condition 2: polypropylene-based resin expanded particle is 100 ℃～140 ℃ low melting point acrylic resin and 20～2 weight part fusing points than the mixture of the high high-melting-point acrylic resin more than 20 ℃ of this low melting point acrylic resin as substrate resin with 80～98 weight part fusing points;

Condition 3: in heat flux differential scanning calorimetry, after with 10 ℃/minute heat-up rates polypropylene-based resin expanded particle being heated to 200 ℃ from normal temperature, with 10 ℃/minute cooling rates it is cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with 10 ℃/minute heat-up rate, from 80 ℃ to being 0.55～0.80 divided by the heat ratio of total endotherm(ic)peak heat gained than the fusion heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle.

Images